+$#>KConcept Valve Train – Introduction

The concept valve train module is divided into seven sections, each section covering a specific area of the concept valve train design or analysis process. The seven sections are;

Profile – This section allows the user to define the polynomial cam function. The currently defined function is displayed graphically. The user can ‘edit’ or ‘joggle’ points on the polynomial function in lift or the first three derivatives. 

Mechanism – This section defines the valve train mechanism data. Depending on the current mechanism type alters what data values are required. The mechanism is displayed graphically in a scale layout allowing the user to ‘edit’ or ‘joggle’ geometry data.

Statics –K This section defines the material and mass type properties associated with the valve train. It also displays graphically a number of the calculated valve train results. 

Valve/Piston Clearance – This section looks specifically at valve to piston clearance. The valve data can either be the currently designed profile or alternatively a valve profile can be imported from the Lotus Engine Simulation environment or as a user specified file. The effect on clearance of valve timing and other related parameters can be examined.

Spring Design – This section allows an automotive style valve spring to be designed. The resultant spring loads can be copied back into the valve train static’s section to be used in spring load related calculations. The spring designed is displayed graphically and to scale, the major dimensions of which can be ‘edited’ or ‘joggled’ on the display.

Overlap Areas – This section allows the overlap duration and area between a pair of valves to be calculated. Poppet valves from the current engine simulation model can be loaded directly into this section to also determine the overlap area in terms of a discharge coefficient based effective area calculated value. The data associated with the overlap calculation can be ‘edited’ or ‘joggled’ on the display.

Dynamic Analysis – This section extends the kinematic analysis section to include the effect of component flexibilities. This dynamic analysis models multi-mass springs, flexible valve and seat as well as a detailed hydraulic tappet model. Racing type gas springs can also be included.

A series of tutorials are available to assist new users learn the features of the code. Open Tutorial

+$#>Profile Section – Overview

In this section the user constructs the Polynomial/Bezier curve to define the valve/cam motion. The complete displacement curve and the first three derivatives, (velocity, acceleration and jerk) are displayed graphically. By default a segmented polynomial curve is pre-defined that the user then can alter the major features of and add additional constraints to the curve. The additional constraints are added by selecting the required ‘greyed out’ points on the displayed curves of lift or the derivatives. The major features include the ramp height and velocities, the symmetry, the maximum displacement and the profile period.

To change templates and/or profile types use the File \ New pull down menu, this will open the New Model dialog box.

The default curve is based on an eleven point/six segment definition, additional definition types are available that uses 15 points and 10 segments for clipped velocity profiles and 17 point with 12 segments for clipped acceleration. Each segment is a polynomial having the required order to suit the number of boundary conditions defined. The polynomial exponents are taken as required from the list of defined exponents. The segment definitions, exponents used, coefficient values and point definitions can be viewed from the ‘solve / list profile segments’ menu. The default point and segment structure is given below.

Points are numbered in sequence through the profile from start to end. For the default polynomial these are;
Point 1 = Bottom of opening ramp, start of constant acceleration portion, (zero lift)
Point 2 = End of constant acceleration ramp, start of constant velocity portion of ramp.
Point 3 = End of ramp, start of opening side main segment.
Point 4 = Point just inside start of main profile segment on opening side.
Point 5 = Mid point of opening side main profile segment.
Point 6 = Max displacement point. End of opening side main segment and start of closing side main segment.
Point 7 = Mid point of closing side main profile segment.
Point 8 = Point just inside end of main profile segment on closing side.
Point 9 = Start of closing ramp constant velocity section, End of closing side main segment
Point 10 = End of constant velocity section of the ramp, start of constant acceleration portion.
Point 11 = End of closing ramp, (zero lift)

Note cam duration is taken as being from point 3 to point 6 for the opening side and from point 6 to point 9 on the closing side, and is always given in cam degrees, (i.e. duration is quoted as top of ramp to top of ramp). There appears to be no single standard when it comes to quoting cam duration, each company seemingly having there own ‘standard’, and care should be taken when comparing ‘duration’ numbers between profile sources.

  	Segment 1: Point 6 to point 9, Main segment on the closing side.
  	Segment 2: Point 9 to point 10, Closing side ramp, constant velocity portion.
  	Segment 3: Point 10 to point 11,Closing side ramp, constant acceleration portion.
  	Segment 4: Point 1 to point 2, Opening side ramp, constant acceleration portion
  	Segment 5: Point 2 to point 3, Opening side ramp, constant velocity portion.
  	Segment 6: Point 3 to point 6, Main segment on the opening side.

The current version of the program divides valve train types into five basic types (or templates);

  	1) Direct Acting
  	2) Rocker, center pivot
  	3) Finger follower, end pivot
  	4) Push rod, rocker
	5) Tappet Rocker

Each basic types can also be defined from either the valve end of the system or the cam end of the system.

Selecting any of the basic types and motion types via the File \ New menu item, will produce a profile based on default data values. These default values will need to be modified to suit the particular design requirements and restrictions. In the ‘New’ dialogue box the user can select from a number of polynomial type options, including ‘user defined’ additionally three Bezier options are available that use segmented Bezier curves in either lift, velocity or acceleration.

+$#>Mechanism Section – Overview

Within this section the user defines geometry of the selected mechanism templates type. The mechanism types being;

1) Direct Acting
2) Rocker, center pivot
3) Finger follower, end pivot
4) Push rod, rocker
5) Tappet, rocker

The defined mechanism is shown drawn to scale in a graphical display, through which the user can ‘edit’ or ‘joggle’ the mechanism radii, lengths, angles or co-ordinates. To fully understand the relevance of each listed mechanism dimension the user should refer to the detailed descriptions given for each data variable in this help file.

As the user changes dimensions on the graphical display the profile is continually re-calculated to show the immediate effect of the change on the resultant passed motion. A number of the data items related to the mechanisms can not be changed directly from the graphical display but must be edited through the data boxes, (or through the additional data values given under the ‘advanced’ button). Changes made via these ‘data boxes’ are not applied until the solution is ‘updated’.

The scaled display can be manipulated with the normal view options of autoscale, zoom or editing of the axis settings.

The scaled display can also be printed to obtain a hard copy or can be included into an electronic document via conventional ‘cut and paste’ or though exporting as a metafile for importing into the required application.

+$#>Static’s Section – Overview

This section allows the user to define physical properties such as mass and load and material properties such as Poissons ratio and Young’s modulus. This section also displays any of the calculated static’s analysis results. The default displayed results are;

1) Spring cover, shows spring load and inertia load
2) Eccentricity
3) Drive Torque
4) Radius of curvature
5) Contact stress
6) Oil film thickness

The settings of these plots can be changed to show any calculated parameters on the x and y axes, (limitation is x and y must be associated, i.e. both are available by cam angle). In addition the form of these plots can be changed to display results as x-y line graphs, bar charts or polar plots.

Additional data items are accessible through the ‘advanced’ button.

As with all the sections the static’s data display screen can be switched to display a summary of the results. These results being shown in ‘red’ when outside of the defined limits.

The six displayed graphs can be printedHOW5 singularly, or as a complete group. They can also be exportedeither as a metafile or via the clipboard for inclusion into other applications.

+$#>Valve to Piston Clearance Section – Overview

This section analyses the valve to piston clearance for a simple flat topped piston. The user can check the clearance of the currently designed profile, a user specified list or, (if the user is licensed to use the Lotus Engine Simulation code) the lift data from a defined valve element can be imported for analysis.

The analysis superimposes the valve motion, (taking valve angle and initial position in to account), over the piston displacement. The minimum clearance is calculated for the defined valve MOP timing, and also for a spread in valve timing 50 crank degrees either side of the defined value.

Four graphs display the calculated/input data, namely;

1) Valve Lift
2) Clearance Diagram, shows lift and piston displacement.
3) Clearance vs angle for the defined timing
4) Minimum Clearance vs cam timing.

The graphs can be displayed together or singularly, with conventional printing and export functions supported for these graphs.

The major parameters of initial perpendicular distance and valve timing can also be ‘edited’ or ‘joggled’ direct from the graphical display of the clearance diagram. The clearance calculations being performed automatically for each change. These values can also be edited from the data display along with other variables , but this requires the solution to be updated to reflect any changes.

If the clearance is being calculated for a valve from the simulation model the changes made to the valve timing can be copied back to the simulation model when the concept valve train module is exited.

As with all the sections the static’s data display screen can be switched to display a summary of the results. These results being shown in ‘red’ when outside of the defined limits.

+$#>Spring Design – Overview

This section allows the user to design a conventional automotive valve spring from basic design data. Currently only constant coil diameter springs designs are supported although progressive rate springs are catered for as well as round, elliptical, square and rectangular wire sections. The objective is to close the loop in the cam design process where the static analysis section requires spring loads.

Spring designs can be performed from a number of directions with regard to wire diameter selection, spring fitted length and stress range.

The spring design is shown graphically to-scale with a summary of its major features at various operating lengths.

The spring diameter, (inner or outer as relevant), can be ‘edited’ or ‘joggled’ in a similar way to the other sections data, this can also be done for the fitted length and the wire diameter.

The advanced button gives access to some of the material related data items such as density and Modulus of Rigidity.

When in the spring design section the calculated spring loads can be made the current inner or outer spring loads as required, within the static’s data section.

+$#>Overlap Area – Overview

This section allows the user to calculate the overlap duration and area between a pair of poppet valves. The valve timing can be varied to assess the impact on the overlap parameters. The valve clearance data at the opening and closing points can be used to either reduce the design lift by the actual operating clearance, or determine the overlap parameters relative to the required lift points. 

A description of the relevant data variables is given in the data section.

If the user has an engine simulation model loaded the data associated with the valves in the model can be used for the overlap calculation. If engine simulation model valves are used then an additional overlap calculation is performed based on the equivalent effective area of the valves.

+$#>Dynamic Analysis – Overview

This section enables the dynamic performance of the valve train system to be analyzed over a range of prescribed runs. The system is modeled as a series of discreet generic lumped-masses connected by non-linear springs. Additional specific elements are included to model the dynamics of hydraulic tappets and gas springs. The system model is displayed on screen for both model editing and analysis results display.

A description of the relevant data variables is given in the data section. Significant use is made of the existing kinematic model and the ADAMS/Engine defaults to assist in fully populating a dynamics model with the minimum of additional user input.

If the user has an engine simulation model loaded the dynamic model created can be used to define a valve element in the engine simulation model as being dynamic. Thus when the engine simulation model is run the valve motion will be predicted by the valve train dynamics module producing a co-simulation between engine and valve train. This co-simulation extends to include passing back to the dynamic model the cylinder pressure data in the relevant cylinder and port. The simulation uses a time marching solver approach with a relaxation method employed to refine/control the solution at each time step based on convergence of mass accelerations. Additional details are given in the theory section

Note; that this section is licensed separately from the main valve train program and thus if you are not currently licensed on this module the relevant menus will be disabled or not visible.

+$#>Description of Menu Items - File

File \ New (all): Starts a new design, (by definition this loses the current data, the user being warned of this and asked to confirm the ‘new’ selection). The user is presented with the ‘new’ dialog box that requires one of the basic templates to be selected and whether cam or valve motion definition is required. The user can also select from the list box, one of the available polynomial and Bezier definition types. Selecting ‘ok’ will create a new data set based on the default values for the particular template.

File \ New (profile): Starts a new profile design all other data is retained, (by definition this loses the current profile data, the user being warned of this and asked to confirm the ‘new’ selection). The user is presented with the ‘new’ dialog box, the basic template selections will be greyed out. The user can select whether cam or valve motion definition is required. The user can also select from the list box, one of the available polynomial or Bezier definition types. Selecting ‘ok’ will create a new profile based on the default values for the existing particular template. The use of this compared to the previous option of New (all), is that the existing mechanism and static’s data can be retained whilst you change to an alternative polynomial definition type, or indeed change to the motion definition type.

File \ New (mechanism): Starts a new mechanism design all other data is retained, (by definition this loses the current mechanism data, the user being warned of this and asked to confirm the ‘new’ selection). The user is presented with the ‘new’ dialog box, the polynomial type box will be greyed out to retain the current profile. The user can select one of the basic templates and whether cam or valve motion definition is required. Selecting ‘ok’ will create a new mechanism data set based on the default values for the particular template. The use of this compared to the earlier option of New (all), is that this allows an existing defined valve motion to be tried on different mechanism without having the tiresome task of redefining the profile data.

File \ Open: Opens the standard Windows file browser allowing the user to select an existing Concept Valve Train file. The default file extension is *.cvt. Selecting ‘open’ will load the chosen file into the application.

File \ Save: Saves the current data to the current file. If the file has not previously been saved or was not loaded from an existing file the ‘Save’ option will default to the ‘Save_As’ menu, (see below).

File \ Save_As: Opens the standard Windows file browser allowing the user to enter a file name to save the current data to. If the file already exists the user is warned and asked to confirm the overwriting of the file. On a successful save the file name is added to the most recent five file list at the end of the ‘File’ menu.

File \ Save_As (Dynamic Results): Saves the current dynamic analysis time history results to a user defined file. If the file already exists the user is warned and asked to confirm the overwriting of the file.

File \ Save_As (Dynamic Summary Results): Opens the standard Windows file browser allowing the user to enter a file name to save the current dynamic analysis summary results to. If the file already exists the user is warned and asked to confirm the overwriting of the file.

File \ Make Current: This menu option will not be available if you are not licensed for the Lotus Engine Simulation product, since this deals directly with that program. It allows the user to copy the current cam profile and/or the dynamic model to a particular valve (or valves) in the current engine simulation model. With the addition of the dynamics section this allows controls the copying of the dynamics model data between the Lotus Concept Valve Train and Lotus Enigne Simulation models. The user is required to identify which valves to copy to, the required valve timing and what clearance values to take off the valve lift. This provides a seamless electronic way of copying cam profile data or dynamics data. The user is warned if this menu item is selected and there are no poppet valves in the current engine simulation model, the menu selection being ignored.

File \ Export \ Export Profile: This menu option opens the ‘data export’ dialog box. This allows the cam profile to be written out in a number of distinct file formats. Its primary use is to export data from Lotus ‘Concept’ and ‘Simulation’ packages into a file format compatible with the relevant Adams Engine product. These files format being the Adams Teimorbit standard. It can also be used as a way of exporting data into a simple column ASCII format, that is in addition to the normal graph and results listing options. Various options are given on export style, decimal points and units.

File \ Export \ Export Spring: This menu option opens the ‘data export’ dialog box. This allows the current spring design properties to be written out in a number of distinct file formats. Its primary use is to export data from Lotus ‘Concept’ and ‘Simulation’ packages into a file format compatible with the relevant Adams Engine product. These files format being the Adams Teimorbit standard. It can also be used as a way of exporting data into a simple column ASCII format, that is in addition to the normal graph and results listing options. 

File \ Export \ Export SubSystem: This menu option opens the ‘data export’ dialog box. This allows the current valve train mechanism to be written out in a number of distinct file formats. Its primary use is to export data from Lotus ‘Concept’ and ‘Simulation’ packages into a file format compatible with the relevant Adams Engine product. These files format being the Adams Teimorbit standard. The sub system export writes all the necessary component property files as well as the overall sub-system file, for further details see how to export an ADAMS/Engine Sub system model.

File \ Export \ Export Cam Cutter Data: This menu option opens the ‘data export’ dialog box. This allows the current cam profile to be written out in the form normally required by the cam grinder, i.e. the translating lift of a radiused follower, for further details see how to export cam cutter data

File \ Export \ Export Lift Profile …(User Format A): This menu option opens the ‘data export’ dialog box. This allows the current cam profile to be written out in a specific User formats. User Format A applies to a specific customer. Additional export filters can be added on request.

File \ Import \ Import 1 deg Lift Definition: This menu option opens the standard file browser, allowing the user to locate and load the required file. The file should be plain ASCII text containing one column of displacement (mm). The displacement will be applied to whichever end of the system is current. This data is then used instead of the polynomial data to define the required motion. The velocity, acceleration and jerk values will de obtained by fitting and differentiating the supplied lift values. (see also Import full profile below). The fitting and differentiation can be controlled through the segment size and the smoothing value. If the displacement is to be applied to the ‘cam’ side of the mechanism and the mechanism type is either a finger (type 2) or rocker (type 3) then the user is asked to define if the displacement is for a translating flat follower or a translating roller follower. The displacement is then converted accordingly into circumferential displacement, (the internal cam side displacement). 

File \ Import \ Import Even Angle+Lift Definition: This menu option opens the standard file browser, allowing the user to locate and load the required file. The file should be plain ASCII text containing two columns of cam angle, (minus through zero to positive) and displacement (mm). The displacement will be applied to whichever end of the system is current. This data is then used instead of the polynomial data to define the required motion. The velocity, acceleration and jerk values will be obtained by fitting and differentiating the supplied lift values. (see also Import full profile below). The fitting and differentiation can be controlled through the segment size and the smoothing value. If the displacement is to be applied to the ‘cam’ side of the mechanism and the mechanism type is either a finger (type 2) or rocker (type 3) then the user is asked to define if the displacement is for a translating flat follower or a translating roller follower. The displacement is then converted accordingly into circumferential displacement, (the internal cam side displacement). The data should be in even angle increments.

File \ Import \ Import Uneven Angle+Lift Definition: This menu option opens the standard file browser, allowing the user to locate and load the required file. The file should be plain ASCII text containing two columns of cam angle and displacement (mm). The displacement will be applied to whichever end of the system is current. This data is then used instead of the polynomial data to define the required motion. The velocity, acceleration and jerk values will be obtained by fitting and differentiating the supplied lift values. (see also Import full profile below). The fitting and differentiation can be controlled through the segment size and the smoothing value. If the displacement is to be applied to the ‘cam’ side of the mechanism and the mechanism type is either a finger (type 2) or rocker (type 3) then the user is asked to define if the displacement is for a translating flat follower or a translating roller follower. The displacement is then converted accordingly into circumferential displacement, (the internal cam side displacement). The data can be in un-even angle increments and either increasing or decreasing values. The angle data is interpolated onto an even increment based on the current angle increment setting.

File \ Import \ Import Full Profile: This menu option opens the standard file browser, allowing the user to locate and load the required file. The file should be plain ASCII text containing five columns of cam angle, (minus through zero to positive), displacement (mm), velocity (mm/deg), acceleration (mm/deg2) and jerk (mm/deg3). The displacement will be applied to whichever end of the system is current. This data is then used instead of the polynomial data to define the required motion, (see also Import lift definition above). Unlike the two options above, if the motion type is ‘cam’ the input is assumed to be circumferential and the option to convert from a translating follower is not given.

File \ Import \ Import Landis 3L-3200 File…: This menu option opens the standard file browser, allowing the user to load a specific format File. The Landis file format is a grinding machine specific format. It is also available for export from the main file Export dialogue box.

File \ Import \ Import Lift Profile… (User Format A): This menu option opens the standard file browser, allowing the user to load a specific format File. User Format A applies to one specific customer. Additional import filters can be added on request.

File \ Import \ Import 2xLift Profiles… (User Format B): This menu option opens the standard file browser, allowing the user to load a specific format File. For this filter two files are required the first for the opening half lift and the second for the closing half lift. User Format B applies to one specific customer. Additional import filters can be added on request.

File \ Load from Spread Sheet: This menu option opens the LESOFT data mange spread sheet to allow ascii file data to be loaded, manipulated and ultimately imported into lotus concept Valve Train. This spread sheet is accessible from any of the Lotus software modules allowing data to be imported and moved between dialogue boxes without recourse to external packages.

File \ Launch ADAMS/Engine: This attempts to open the ADAMS/Engine (view) application. Obviously ADAMS/engine must be installed on the host machine/network for this to work. The actual command string used by this menu option can be edited through the ‘setup’ menu options.

File \ Close (make current): As for the normal make current option this allows the user to copy the current cam profile to a particular valve (or valves) in the current engine simulation model, (see above for further details). In addition this menu option closes the Lotus Concept Valve Train main window and depending on your license options will either return to the main simulation window or close the application completely. The later option being the case for users licensed for the Concept Valve Train program only.

File \ Close (return to Simulation): This menu option closes the Lotus concept Valve Train main and will return to the main simulation window. This option is only available if the valve train tool was opened from the simulation window.

File \ Exit: This menu option closes the Lotus concept Valve Train application. If the valve train tool has been opened from the engine simulation environment, this menu item will not be visible.

At the end of the ‘File’ menu are listed up to five of the last files used by the Concept Valve Train program.

+$#>Description of Menu Items - Section

Section \ Profile: Changes to the ‘Profile’ section of the Lotus Concept Valve Train program. This can also be achieved by simply selecting the ‘Profile’ tab from those shown along the top of the dialog box.

Section \ Mechanism: Changes to the ‘Mechanism’ section of the Lotus Concept Valve Train program. This can also be achieved by simply selecting the ‘Mechanism’ item from the selection box at the top of the dialog box.

Section \ Static’s: Changes to the ‘Statics’ section of the Lotus Concept Valve Train program. This can also be achieved by simply selecting the ‘Statics’ item from the selection box at the top of the dialog box.

Section \ Valve/Piston Clr: Changes to the ‘Valve to Piston Clearance’ section of the Lotus Concept Valve Train program. This can also be achieved by simply selecting the ‘Valve/Piston Clr.’ Item from the selection box at the top of the dialog box.

Section \ Spring Design: Changes to the ‘Spring Design’ section of the Lotus Concept Valve Train program. This can also be achieved by simply selecting the ‘Spring Design’ item from the selection box at the top of the dialog box.

Section \ Overlap: Changes to the ‘Overlap’ section of the Lotus Concept Valve Train program. This can also be achieved by simply selecting the ‘Overlap’ item from the selection box at the top of the dialog box.

Section \ Dynamic Spring: Changes to the ‘Dynamic Spring’ section of the Lotus Concept Valve Train program. This can also be achieved by simply selecting the ‘Dynamic Spring’ item from the selection box at the top of the dialog box. If you are not licensed for this module this menu option and its associated selection box entry will not be visible.

+$#>Description of Menu Items – Data Mode

Edit: Sets the data modification mode to EDIT. Thus selecting a point or position will results in the data entry dialogue box being displayed to enable the value to be changed.

Joggle: Sets the data modification mode to JOGGLE. Thus selecting a point or position will results in the joggle graphical symbol being displayed to enable the value to be changed via the keyboard keys.

Clip and Replace: Sets the data modification mode to CLIP and REPLACE. This edit mode is only applicable to the Profile section and when cam/valve lift data has been imported. A selected point can be replaced by an interpolated value to aid data preparation.

Drag: Sets the data modification mode to DRAG. Thus selecting a point or position will results in the drag graphical symbol being drawn. The selected point can then be moved around the display by holding the mouse button down and moving the screen cursor.

Add Bezier Point: Sets the data modification mode to ADD BEZIER POINT. This is only applicable to the Profile section and when using the Segmented Bezier approach to profile design. Selecting on the relevant graph will add an additional point to the current Bezier curve. The point will be added based on its ‘x’ position provided with the exception that it cannot be one of the first two points or last two points.

Delete Bezier Point: Sets the data modification mode to DELETE BEZIER POINT. This is only applicable to the Profile section and when using the Segmented Bezier approach to profile design. Selecting on the relevant graph will remove the nearest Bezier curve point. Only additional points can be deleted, it cannot be one of the first two points or last two points within a curve.

+$#>Description of Menu Items - Graph

Graph \ Autoscale (Ctrl+A): Autoscales the currently displayed graph, (or graphs) such that all relevant portions of the graph are visible. This can also be achieved using the menu shortcut ‘Ctrl+A’ keyboard combination. The autoscale option can also be selected via the right mouse button menu. In this case it will only apply to the graph on which the right mouse click was made

Graph \ Zoom: Allows the user to zoom into a specific region of a displayed graph or graphic. Both ‘pick hold down and drag a rectangle’ and ‘pick release drag and pick again’ styles are supported. The zoom option can also be selected via the right mouse button menu. A zoom is ignored if it does not stay within the bounds of a single graph or graphic.

Graph \ Scope: Provides a method for cross plotting different profiles and results. The sub menus under ‘scope’ provide the option to control the visibility of any stored lines, capture current displays, load saved results and set the colour of each scope ‘channel’. The ‘scope’ feature works like an oscilloscope, in that the displayed lines can be captured and then subsequently compared to later plots. Scope is applicable to Profile, Statics and Dynamic spring sections only.

Graph \ Scope \ On: Controls the visibility of the ‘scope’ feature. The menu item is ‘checked’ when on.

Graph \ Scope \ Store: This provides a series of menus that allow the current display to be ‘stored’. Storing can be to any one of the five channels either by specifically storing to a channel number or into channel 1 having shuffled the existing scopes down one channel. Displays can also be ‘stored’ in exclusive mode where all channels are cleared before storing the current display. Previously stored dynamic displays can be added to a scope channel through the additional ‘load’ menu items, (the dynamic displays are saved via the file \ save_as menu items). 

Graph \ Scope \ Clear: This clears the stored data from the specified channel.

Graph \ Scope \ Line Colour: This opens a colour tablet from which the user can select the required line colour. Only the specified scope position is affected.

Graph \ Set Statics Graph Variables: This menu option has a sub-menu that lists the six statics analysis graphs, (position 1 to position 6). By selecting the required graph from the sub menu the settings for that graph position can be defined. This includes the plot type, i.e. line, bar or polar and the x and y axis variables.

Graph \ Edit Axis Settings: This menu option has a sub menu that list all of the graphs or graphics within the various sections of the Concept Valve Train program. By selecting the required graph from the sub menu the user can set the x and y axis settings, defining the axis start value, end value and step size. The right mouse button also has an ‘Edit Axis Settings’ menu item that allows the specific display to be set, since the position of the right mouse click dictates the display to be edited.

Graph \ Edit Label Settings: This menu option has a sub menu that list all of the graphs or within the various sections of the Concept Valve Train program. By selecting the required graph from the sub menu the user can set the x-axis label, y-axis label and the graph title. These settings are saved to the users ‘ini’ file.

Graph \ Set Point Symbol: This menu option has a sub menu that list the available symbol types. The default symbol is the ‘filled circle’ but users can select other available symbol types for use on the graphs in the profile definition section.

Graph \ Edit Graphics Symbol Sizes: The displayed dialogue box allows the users to set the size of the graphics symbols on the profile sections graphs and also the C of G marker size on the mechanism section display.

Graph \ Copy to Clipboard: The displayed graph(s) or graphic can be copy to the standard windows clipboard, to allow a low quality graphical ‘cut and paste’ operation to other applications that support this type of activity. (higher quality electronic copies of the graphical displays can be achieved via the ‘graph \ export’ menu using a windows metafile.

Graph \ Print  (Ctrl+P): Prints a copy of the currently displayed graph(s) or graphic. The standard windows file print dialog box is displayed to allow the user to select the required printer and associated settings. (Note that currently selecting cancel will give the user a warning message).

Graph \ Allow Resize on Print: When set, printed graphs will be expanded to fill the available page space. Only applicable to plotting from Profile, Statics, Valve/Piston Clearance and Overlap sections.

Graph \ Export: Saves the current graph(s) or graphic to a windows metafile. This menu option opens the standard Windows file browser, to enable the user to select the required file name to save the current sections displayed graphic to. Supported file format are limited to Windows Metafiles (*.wmf).

Graph \ Colours \ Line1 colour: This series of menus allows the user to change the settings used for the ‘standard’ line colours used within the interface. Note that the 7 ‘standard’ colours will be used in a number of positions throughout the application and thus a change in one area may not suit another. These settings are saved to the users ini file.

+$#>Description of Menu Items - Solve

Solve \ Update: Updates the profile solution. This menu option is equivalent to pressing any of the calculator style buttons that appear on each of the sections with the program. All perform the same level of calculations running right through and updating every section irrespective of which section is currently displayed.

Solve \ Update (rebuild): This is similar to the menu item above except that it removes any segment information relating to the intermediate points of the main profile segments. The user is asked to confirm that it is okay to proceed since this will result in a loss of information. All other profile data values are retained, but it is useful for reverting back to an unrestrained polynomial.

Solve \ Update During Drag: Sets the solution update such that all calculations are performed and displays refreshed as the points are dragged. This will make the dragging operation somewhat ‘jerky’ but ensures all values are current.

Solve \ Update on Drag Release: Sets the solution update such that only the local graphical display is updated during the dragging. All calculations are performed and displays refreshed once the drag event is finished with the release of the mouse key. This will produce smoother dragging operation but some displayed results, (i.e. summary table will not be updated untl the key is released).

Solve \ Retain User Points on Change: When checked this enables the user to modify the ramp or duration properties without losing any intermediate point definitions. If this is unchecked all user defined points are lost on a change in ramp or duration.

Solve \ Bezier Options \ Bezier Match Velocity at Max Lift: Only applicable when in the Profile section and defining the profile using the Piecewise Bezier approach. This performs an auto fit in terms of matching the velocity to zero at the maximum lift point. The currently selected point and selected Bezier move mode is used as the allowable degree of freedom, the point be manipulated until a match is achieved within tolerance.

Solve \ Bezier Options \ Bezier Match Lift at Closing Ramp: Only applicable when in the Profile section and defining the profile using the Piecewise Bezier approach. This performs an auto fit in terms of matching both the velocity and lift at the top of the closing ramp. This approach is only needed when matching an asymmetric cam, the previous menu option being sufficient for symmetrical cams. The asymmetric profile needs to move two Bezier points to achieve the match, these points are prompted for and must be different.

Solve \ Bezier Options \ Bezier New Profile Settings: When a new profile is created based on the Piecewise Bezier approach a number of default values are used to produce the complete curve. These include acceleration ratios flank/nose initial opening jerk values and the jerk through the zero acceleration point. These defaults can be edited prior to creating a new profile through this menu.

Solve \ Bezier Options \ Derivative Fitting Settings: When a new profile is created based on the Piecewise Bezier approach a number of default values are used to produce the complete curve. As well as the values edited by the previous menu item an number of fitting routines are employed to derive the curve derivatives and integrals (as required). The settings for these fits are controlled by a series of default polynomial segment size and order coefficients. These defaults can be edited prior to creating a new profile through this menu.

Solve \ Bezier Options \ Bezier Drawing Buffer Sizes: These variables control the size of the graphics buffer created to store the points used to draw the Bezier curve. The default sizes should be adequate, users only need to change these if indicated by graphics error messages.

Solve \ Bezier Options \ Bezier Solution Tolerance Settings: These variables control the size of initial increment used to move the selected point(s) when performing the iterations and the tolerances required for an acceptable convergence in terms of lift (mm) and velocity (mm/deg).

Solve \ Auto-Fit Polynomial to Data: This runs the ‘auto-fit’ utility. This menu item is only enabled when profile data has been imported through one of the ‘file import’ options. This runs a procedure that identifies the profile properties/features and fits a segmented polynomial to it minimising the deviation from the imported values using the current ‘auto-fit’ settings. The ‘auto-fit’ settings can be modified through a separate dialogue box, (see menu item below).

Solve \ Auto-Fit Settings: Opens the ‘auto-fit’ property box. The properties displayed control how the fitting process is to be carried out. Individual derivatives can be omitted/included into the fitting assessment with unique weighting factors. Additional parameters control the number of points to ignore at the start and end of the list, the power of the fit, (i.e 2 =least squares), and the tolerances that should be used to identify profile features such as constant velocity sections. With unusual profile forms it may be necessary to experiment with these properties to achieve an acceptable fit level.

Solve \ Edit Point Coupling: Point coupling provides a method by which points on a derivative curve can be coupled such that editing (or joggling) one point in the group automatically updates the others in the group. The effect of symmetry/mirror symmetry is included. The menu items opens the dialogue box through which point couples can be created and edited. Multiple groups can be created the only limitation being that all the points in a group must be on the same derivative curve. Up to 10 point couples can be created with up to 10 points in each coupling. This dialogue box also provides access to the switch settings to make polynomial point No’s visible and also to enable point coupling, (these can also be accessed more normally through their respective ‘view’ menu items).

Solve \ Edit Float Cover Settings: This allows the user to edit the values used to estimate the float speeds from the rigid body static’s approach. An assumed margin, (or cover), between the spring loads and the system inertia loads is taken to be required to cover the dynamic effects of system and spring vibrations. A different value is used for each template type to reflect their inherent differences in stiffness. The default values can be changed to assist in any float speed correlation exercise. The default values are; for ‘Direct-Acting’ =1.1, for ‘Rocker Centre Pivot’ = 1.15, for ‘Finger Follower – End Pivot’ = 1.15 and for ‘Push Rod – Rocker’ = 1.25

Solve \ Limits \Edit Cam Limit Settings: This allows the user to edit the limiting values used for the summary report of the calculated values. If the calculated value exceeds the defined limit then the calculated value is shown in the report highlighted in red. This menu entry deals specifically with those associated with the displayed cam results.

Solve \ Limits \ Edit Valve Limit Settings: This allows the user to edit the limiting values used for the summary report of the calculated values. If the calculated value exceeds the defined limit then the calculated value is shown in the report highlighted in red. This menu entry deals specifically with those associated with the displayed valve results.

Solve \ Limits \ Edit Statics Limit Settings: This allows the user to edit the limiting values used for the summary report of the calculated values. If the calculated value exceeds the defined limit then the calculated value is shown in the report highlighted in red. This menu entry deals specifically with those associated with the displayed static’s results, (see also menu item below).

Solve \ Limits \ Edit Statics(2) Limit Settings: This allows the user to edit the limiting values used for the summary report of the calculated values. If the calculated value exceeds the defined limit then the calculated value is shown in the report highlighted in red. This menu entry deals specifically with those associated with the displayed static’s results, (see also menu item below).

Solve \ Set All Limits to Current Profile: This option uses the current profile to set all the warning limits. Thus at a single stroke the targets can be set to an analysed profile for comparison with other profiles.

Solve \ Set All Limits to Internal Defaults: This returns all warning limits to the internally hard coded options. Resetting any user editing.

Solve \ Edit Joggle Sizes: User edit of joggle sizes. The user can define the graphical increment size for any point that can be ‘edited’ or ‘joggled’ on its display, this includes points on the polynomial curves, pivot points and dimensions on the mechanism display and dimensions on the spring graphic.

Solve \ List Profile Segments: Displays segment properties and definitions. The displayed dialog box shows a list of all the profile point definitions, giving values for lift, velocity acceleration and jerk curves. Each point has two values for each derivative, being the value either side of the point, (i.e. discontinuities are possible). In addition each point has two characters identifying whether that derivative is free (F), defined (D), un-defined (U), continuous (C) or evaluated (E). The points shown in red are the one associated with the current displayed segment. The currently displayed segment is changed through the top selection box, which lists the points associated with the segment, the polynomial exponents and the calculated polynomial coefficients for each term by derivative.

Solve \ Use Individual Exponent Tables: This switch toggles between the use of a single look-up table for the polynomial exponents and a 2d table where each profile segment has its own unique set of polynomial exponents.

Solve \ Edit Exponent Table(s): The values in the polynomial table(s) can be viewed and edited either through this menu item or via the Poly Expons button on the profile property panel.

Solve \ Dynamic Exponent Table(s): This feature provides a interactive method by which the polynomial exponents can be modified and the effect on the profile, ( and its derivatives), examined. A series of sliders allow the user to step an individual exponents value with high/low watermark trapping.

Solve \ Edit User Defined Polynomial: This menu is only enabled if the user has selected  ‘user defined polynomial’ from the ‘new’ dialogue box. Once enabled the opened dialogue box is used to create points, build segments and define boundary conditions for the user defined polynomial. The use of user defined polynomials is intended for experienced users only.

Solve \ Copy spring design to Static’s: Updates the spring load data in the static’s data section. This user can copy the spring design loads into the spring load data used within the static’s section. The load data will be copied to either the outer or inner springs, (as selected), and will be in the form of a variable rate spring, (even if linear), listing the spring load against spring deflection. This will obviously lose the existing spring load data held in the static’s section. This menu item is only accessible from the spring design section.

Solve \ Auto-Copy spring design to Static’s: Allows the user to set the copy of spring data to the static’s section to happen automatically whenever the spring design is changed. This ensures that the spring design is continuously linked to the spring properties in the static’s section. Users should note that this setting is not stored in the model file and thus needs to be re-set if required when re-opening the application. This menu item is only accessible from the spring design section.

Solve \ Retain Cam Lobe on Change: This option is only applicable for imported valve/cam lift data. When set it ensures that as you change the mechanism geometry the lobe is retained and the effective lift re-evaluated on the new geometry. To revert to a retained motion and a varying cam profile, un-select this option.

+$#>Description of Menu Items – Dynamic Spring

DynSpring \ Model \ Create Full Dynamic from Current Static Design Data: Provides a one-click easy creation for a number of model types. The nine model types are listed in a sub-menu and reflect the three different tappet options, (Mechanical, Hydraulic and CamProfileSwitching) and the three spring options, ( single wire , double wire and pneumatic). On selection of the required option the combination of the current kinematic data and the default ADAMS/Engine data is used to fully populate the selected dynamic model template.

DynSpring \ Model \ Create Dynamic Spring 1 from: Provides a one-click easy creation of the spring portion of the dynamic model for spring 1, (spring 1 and spring 2 refer to the inner and outer springs although there is no significance in which is 1 and which is 2 but users should use 1 first and then if required add the second). The spring mass elastic model can either be created from the Current Static Design Data or via a series of User Specified Spring Props.

DynSpring \ Model \ Create Dynamic Spring 2 from: As for menu above but for spring 2

DynSpring \ Model \ Update Stem Link Properties from Current Geometry: Performs a stiffness calculation for the valve stem linkage only. Uses the current geometry and/or the ADAMS/Engine defaults to perform the calculation.

DynSpring \ Model \ Update Seat Link Properties from Current Geometry: Performs a stiffness calculation for the valve seat linkage only. Uses the current geometry to perform the calculation.

DynSpring \ Model \ Update Seat Link Properties (use Def. Adams Seat): Performs a stiffness calculation for the valve seat linkage only. Uses the current ADAMS/Engine defaults to perform the calculation.

DynSpring \ Model \ Update Cam Contact Link Properties from Current Geometry: Performs a stiffness calculation for the cam contact linkage only. Uses the current geometry to perform the calculation.

DynSpring \ Model \ Update Valve Tip Link Properties from Current Settings: Performs a stiffness calculation for the valve tip linkage only. Uses the current geometry to perform the calculation.

DynSpring \ Model \ Update Valve Head Mass Properties from Current Geometry: Performs a mass calculation for the valve head mass only. Uses the current geometry and/or the ADAMS/Engine defaults to perform the calculation.

DynSpring \ Model \ Update Retainer Mass Properties from Current Settings: Performs a mass calculation for the valve head mass element only. Uses the current geometry and/or the ADAMS/Engine defaults to perform the calculation.

DynSpring \ Model \ Solid Tappet Mass Properties from Current Settings: Updates the model to use a mechanical tappet. Performs a mass calculation for tappet mass element only. Uses the current geometry and/or the ADAMS/Engine defaults to perform the calculation.

DynSpring \ Model \ Hydraulic Tappet Properties from Adams/Engine Settings: Updates the model to use a hydraulic tappet. Uses the current geometry and the ADAMS/Engine defaults to perform the update.

DynSpring \ Model \ Add CPS Outer Hydraulic Tappet using Defaults: Updates the model to include a Cam Profile Switching (CPS) outer hydraulic tappet. Uses the current geometry and the ADAMS/Engine defaults to perform the update.

DynSpring \ Model \ Create Lost Motion Spring 3 from: Provides a one-click easy creation of the lost motion spring portion of the dynamic CPS model, (spring 3). The spring mass elastic model can either be created from the Current Static Design Data or via a series of User Specified Spring Props.

DynSpring \ Model \ Copy Current Hydraulic Tappet Props to Adams/Engine Settings: Short cut menu item that provides a convenience feature for copying the currently defined hydraulic tappet data back to the defaults. Any subsequent exported Adams/Engine models would then use the same values as contained in the model.

DynSpring \ Model \ Remove Second Spring from Current Model: Menu item that provides a convenience feature for removing the 2nd spring from the model. Is only active when more than one spring is modelled.

DynSpring \ Run \ Initialize and Start Dynamic Spring Run: Initializies the dynamic model and starts the calculation run currently defined. The user is asked to confirm that it is okay to start an analysis run as any unsaved results from a previous run will be lost.

DynSpring \ Run \ Stop/Pause Dynamic Spring Calculation: Stops the current calculation run. A stop can be viewed either as a premature end to the defined run or simply an option to pause the run to either step through a portion of the run or review the current results. A job ‘paused’ in this way can be re-started from the same point using the ani8mation toolbar icons.

DynSpring \ Display \ Values: Controls the visibility of the results values drawn adjacent to the relevant model part.

DynSpring \ Display \ Time History: Controls the visibility of the ‘Time History’ lines drawn horizontally next to the relevant model element.

DynSpring \ Display \ Filled Tappet Display: For a hydraulic tappet model this controls the visibility of the colour fill of the tappet high and low pressure regions. The fill colours change to represent the current calculated pressure value.

DynSpring \ Display \ Filled Tappet Settings…: Opens a dialogue box that allows control of the contouring used to colour fill the hydraulic tappet high and low pressure regions.

DynSpring \ Display \ 2nd Zoom Window: Controls the visibility of the 2nd local zoom window that is drawn with its own scale and model position to allow a detailed view of a portion of the model to be viewed independent of the main display.

DynSpring \ Display \ Filled Gas Spring Display: For a gas spring model this controls the visibility of the colour fill of the spring feed exit and chamber pressures. The fill colours change to represent the current calculated internal pressures.

DynSpring \ Display \ Filled Gas Spring Settings…: Opens a dialogue box that allows control of the contouring used to colour fill the gas spring pressure regions.

+$#>Description of Menu Items – Text Results

Text Results \ List Cam Values: Displays a list of the results for the cam spline. The opened dialog box lists in a spread sheet for each angle increment, (where –ve is opening side, 0=maximum opening point and +ve is the closing side), the results associated with the cam spline, namely;
		Cam Lift (mm)
		Cam Velocity (mm/deg)
		Cam Acceleration (mm/deg2)
		Cam Jerk (mm/deg3)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel. For finger (type 2) and rocker (type 3) the cam results listed are ‘circumferential’ values. The other types list follower translating values.

Text Results \ List Valve Values: Displays a list of the results for the valve spline. The opened dialog box lists in a spread sheet for each angle increment, (where –ve is opening side, 0=maximum opening point and +ve is the closing side), the results associated with the valve spline, namely;
		Valve Lift (mm)
		Valve Velocity (mm/deg)
		Valve Acceleration (mm/deg2)
		Valve Jerk (mm/deg3)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel.

Text Results \ List Rocker Values: Displays a list of the results for the rocker. This option is  not available for direct acting systems (type 1). The opened dialog box lists in a spread sheet for each angle increment, (where –ve is opening side, 0=maximum opening point and +ve is the closing side), the results associated with the rocker, namely;
		Rocker Angle (deg)
 		Rocker angle (rad)
		Rocker Angular Velocity (rad/deg)
		Rocker Angular Acceleration (rad/deg2)
		Rocker Angular Jerk (rad/deg3)
		Rocker Lift Ratio  (Valve/Cam) 
		Force Ratio  (Valve/Cam)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel.

Text Results \ List Cam Chordal Values: Displays a list of the results for the cam spline in terms of chord properties rather than the previous circumferential values. The opened dialog box lists in a spread sheet for each angle increment, (where –ve is opening side, 0=maximum opening point and +ve is the closing side), the results associated with the cam spline, namely;
		Cam Lift (mm)
		Cam Velocity (mm/deg)
		Cam Acceleration (mm/deg2)
		Cam Jerk (mm/deg3)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel. This option is only available for finger (type 2) and rocker (type 3).

Text Results \ List Cam Centre Values: Displays a list of the results for the cam spline in terms of centre properties rather than the previous circumferential or Chordal values. The opened dialog box lists in a spread sheet for each angle increment, (where –ve is opening side, 0=maximum opening point and +ve is the closing side), the results associated with the cam spline, namely;
		Cam Lift (mm)
		Cam Velocity (mm/deg)
		Cam Acceleration (mm/deg2)
		Cam Jerk (mm/deg3)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel. This option is only available for finger (type 2) and rocker (type 3).

Text Results \ List Static’s Values(1): Displays the first list of the results for the valve train static’s. The opened dialog box lists in a spread sheet for each angle increment, (where –ve is opening side, 0=maximum opening point and +ve is the closing side), the main static’s analysis results, namely;
		Spring Force (at cam) (N)
		Inertia Force (at cam) (N)
		Spring Force (at valve) (N)
		Inertia Force (at valve) (N)
		Design Speed Force (at valve) (N)
		Eccentricity (mm)
		Eccentricity @cam (mm)
		Radius of Curvature (mm)
		Zero Speed Stress (N/mm2)
		Design Speed Stress (N/mm2)
		Zero Speed Drive Torque (N.mm)
		Design Speed Drive Torque (N.mm)
		Zero Speed Friction Drive Torque (N.mm)
		Design Speed Friction Drive Torque (N.mm)
		Oil Film Thickness (m)
		Cam Contact Ellipse Major Semi-axis (zero speed) (mm)
		Cam Contact Ellipse Minor Semi-axis (zero speed) (mm)
		Cam Contact Ellipse Major Semi-axis (design speed) (mm)
		Cam Contact Ellipse Minor Semi-axis (design speed) (mm)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel.

Text Results \ List Static’s Values(2): Displays the second list of the results for the valve train static’s. The opened dialog box lists in a spread sheet for each angle increment, (where –ve is opening side, 0=maximum opening point and +ve is the closing side), the main static’s analysis results, namely;
		Pressure Angle (deg)
		Sliding Velocity (mm/s)
		Entrainment Velocity (mm/s)
		Lube No. (mm/rad)
		Oil Film Thickness (m)
		Specific Film Thickness (-)
		Effective mass at Valve (kg)
		Zero Speed Valve Tip Force (N)
		Design Speed Valve Tip Force (N)
		Valve Tip Pressure Angle (deg)
		Valve Tip Contact Offset (mm)
		Zero Speed Valve Tip Stress (N/mm2)
		Design Speed Valve Tip Stress (N/mm2)
		Valve Tip Contact Ellipse Major Semi-axis (zero speed) (mm)
		Valve Tip Contact Ellipse Minor Semi-axis (zero speed) (mm)
		Valve Tip Contact Ellipse Major Semi-axis (design speed) (mm)
		Valve Tip Contact Ellipse Minor Semi-axis (design speed) (mm)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel.

Text Results \ List Lobe Values: Displays a list of the results for the camshaft lobe. The opened dialog box lists in a spread sheet for each angle increment, (where –ve is opening side, 0=maximum opening point and +ve is the closing side), the camshaft lobe surface results, namely;
		Radius to Point (mm)
		Angle to Point (deg)
		X coordinate of Point (mm)
		Y coordinate of Point (mm)
		Cutter Pressure Angle (deg)
		Cutter Eccentricity at Cam (mm)
		Cutter Eccentricity at Surface (mm)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel.

Text Results \ Fourier Analysis of Valve Motion: Displays a list of the results for the Fourier analysis of the valve motion. Given for lift and the first three derivatives is the mean value and then the magnitude and phase of the first 24 orders. The orders are based on 360 camshaft degrees as the time base, (hence no ½ order content).

Text Results \ List Clearance Values: Displays a list of the results for the valve to piston clearance analysis. The opened dialog box lists in a spread sheet for each crank angle increment, (from 0 to 720 degrees for 4-stroke), the results from the valve to piston clearance calculations, namely;
		Crank Angle (deg)
		Valve Lift (mm)
		Valve Axial Lift (mm)  (distance along bore axis)
		Piston Travel from TDC (mm)
		Valve Clearance (mm)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel.

Text Results \ List Spring Values: Displays a list of the results for the current spring design. The opened dialog box lists in a spread sheet for each increment of spring travel, (from 0 to solid length), the results for the current spring design, namely;
		Lift from Fitted (mm)
		Length (mm)
		Load (N)
		Rate (N/mm)
		Stress (N/mm2)
		No of Active coils (-)
		Natural Frequency (Hz)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel. This menu is only available from the Spring Design section.

Text Results \ List Overlap Data Values: Displays a list of the data/results for the current overlap calculation. The opened dialog box lists in a spread sheet for each crankshaft angle between 0 and 720 degrees, the input data (and results) for the current overlap calculation, namely;
		Crank Angle (deg)
		Inlet Lift (mm)
		Exhaust Lift (mm)
		Corrected Inlet Lift (mm) (modified for clearance)
		Corrected Exhaust Lift (mm) (modified for clearance)
		Inlet Effective Area (mm2)
Exhaust Effective Area (mm2)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel. This menu is only available from the Overlap section.

Text Results \ List Overlap Area Values: Displays a list of the results for the current overlap calculation. The opened dialog box lists in a spread sheet for each crankshaft angle during the overlap portion, the results for the current overlap calculation, namely;
		Crank Angle (deg)
		Overlap Lift (mm)
		Overlap Area (mm.deg)
		Equivalent Overlap Effective Area (mm2)
		Equivalent Overlap CF-area (mm2.deg)
The displayed values can be saved to a file or pasted into other applications, i.e. Excel. This menu is only available from the Overlap section.

Text Results \ List Mechanism Point Co-ordinates: Displays a list of the x-y positions for the mechanism points against cam angle. The actual No. of points listed depends on the mechanism type currently being evaluated. This menu option is only available from the mechanism section.

Text Results \ List Mechanism Point Zero Speed Forces: Displays a list of the forces calculated for the static test point, (0 rpm), in the mechanism. The actual No. of points listed depends on the mechanism type currently being evaluated. This menu option is only available from the mechanism section.

Text Results \ List Mechanism Point Design Speed Forces: Displays a list of the forces calculated for the dynamic test point, (design speed), in the mechanism. The actual No. of points listed depends on the mechanism type currently being evaluated. This menu option is only available from the mechanism section.

Text Results \ Write Text File: Writes the current profile spline data to a text file. The standard Windows browser is opened to allow the user to select a file name to save the current profile to. The created ASCII column file will contain the profile results for both the cam and valve ends, namely;
		Cam Lift (mm)
		Cam Velocity (mm/deg)
		Cam Acceleration (mm/deg2)
		Cam Jerk (mm/deg3)
		Valve Lift (mm)
		Valve Velocity (mm/deg)
		Valve Acceleration (mm/deg2)
		Valve Jerk (mm/deg3)

Text Results \ Write Report to Text File… (Preview): Opens a dialogue box that previews a text file version of the ‘Report’ list normally displayed down the right hand side of the main display. This text list can be saved to a file or printed directly.

Text Results \ Write Report to Text File…: Opens the standard file browser window to define the name and location of the target file that the ‘Report’ summary will be written too.

+$#>Description of Menu Items - View

View \ Toolbars: This controls the visibility of the individual toolbars. A tick next to the individual toolbars sub-menu entry indicates that the specific toolbar should be visible. The three toolbars are the ‘Standard’, ‘Graphic Control’ and ‘Piecwise Bezier’.

View \ Side Panel: This controls the visibility and contents of the side panel. The visibility of the side panel can be  switched ‘off’ to provide more screen space for the graphical display, it can list the relevant ‘data’ for the current section or it can be set to display the summary ‘report’ of the current results. The side panel settings can also be controlled by the toolbar buttons.

View \ Profile Graph: Sub menu lists the selection options of the available graphs for the Profile section.

View \ Statics Graph: Sub menu lists the selection options of the available graphs for the Statics section.

View \ Valve/Piston Clr. Graph: Sub menu lists the selection options of the available graphs for the Valve/Piston Clr. section.

View \ Overlap Graph: Sub menu lists the selection options of the available graphs for the Overlap section.

View \ Joggle Points: Controls the visibility of the graphics marking the graphic editable dimensions and properties. A number of the sections have dimensions drawn on the graphic displays, (using red arrows), that can be selected directly from that graphic. Selecting them they can then be ‘edited’ or ‘joggled’ interactively without the need for the ‘data’ items display to be visible. This can be used to check how calculated results such as time area change as you move a particular pivot point or vary a geometric length. This menu items controls only the visibility of the red arrows that are used to indicate the positions and sizes of these ‘pickable’ data points. It does not actually prevent a user from picking a editable graphic point. 

View \ Segment Lines: Controls the visibility of the yellow vertical lines on the ‘profile’ sections graphs, that mark the start and ends of the polynomial segments that make up the complete lift curve. This menu option simply acts as an ‘on’/off’ visibility toggle.

View \ Data Point Symbols: Controls the visibility of the data points ‘profile’ sections graph. This is only applicable when the profile data is defined by a list of points and not for the polynomial definition approach.

View \ Data Point No.s: Controls the visibility of the numerical label for the data points in the ‘profile’ sections graph. This is only applicable when the profile data is defined by a polynomial and not for a profile defined by a list of points.

View \ View/Use Segment Point Coupling: Enables the visibility and use of any point couplings that have been defined. To create the point groups see under ‘solve’ menus. Point couplings enable relationships between point to be defined such that a shift in one is echoed in the other points in the group.

View \ View Spring Line on Accel: Controls the visibility of the ‘scaled’ spring line drawn on the acceleration curve. It illustrates not only the relevant shape but also the point of minimum cover for the opening half.

View \ View/Edit Component C of G’s: Controls the visibility of the individual component C of G symbols on the mechanism sections graphical display. These C of G markers can then be ‘picked’ to access/edit the dimension used to calculate the mass of a component. This is particularly relevant when calculating the effective mass on the basis of individual component weights.

View \ View Extended Component Graphics: Controls the visibility of the extended graphics option. Currently this only changes how the valve spring and retainer is drawn on the mechanism display. When ‘off’ no spring image is drawn. When ‘on’ the current as defined spring in the ‘spring’ section is drawn.

View \ Zero Speed Contact Ellipse: Controls the visibility of the contact ellipse for zero speed. Contact ellipses are drawn for both the cam interface and the valve tip contact.

View \ Design Speed Contact Ellipse: Controls the visibility of the contact ellipse for the design speed. Contact ellipses are drawn for both the cam interface and the valve tip contact. Only one of the zero or design speeds can be displayed so that this will switch between them if the other speed is currently visible.

View \ View Zero Speed Forces: Controls the visibility of the zero speed force/torque arrows on the mechanism display. The zero speed force option draws scaled arrows with textual values on the mechanism display indicating magnitude and direction of the static forces in the system. If the design speed force display was ‘on’ this is turned ‘off’ as only one set of forces can be displayed at one time. The forces display will be animated to show changes in forces when the mechanism animation is run.

View \ View Design Speed Forces: Controls the visibility of the design speed force/torque arrows on the mechanism display. The design speed force option draws scaled arrows with textual values on the mechanism display indicating magnitude and direction of the design speed forces in the system. If the zero speed force display was ‘on’ this is turned ‘off’ as only one set of forces can be displayed at one time. The forces display will be animated to show changes in forces when the mechanism animation is run. The design speed forces are the kinematic results for the defined ‘design speed’.

View \ Forces and Torque’s Display Settings: Controls the setting for the display of the zero speed/design speed kinematic forces and torques. The user can individually switch forces, toques and values on/off as well as setting the colours and scale factors used for drawing.
 
View \ Display Static’s Results: Controls the visibility of the statics results curve. This is an additional line draw scaled on the cam profile that is orientated  with the lobe to indicate the position and magnitude of a particular statics result (i.e. contact stress) in relation to the mechanism. The currently displayed statics result is indicated in the top left corner of the mechanism display.

View \ Static’s Result Display Settings: Controls the settings used for the ‘on mechanism’ static’s result display. The user can select the results parameter to display, the type of display and associated colours. Additional options allow for the absolute value to be displayed which can be useful for parameters such as velocity and eccentricity that have a sign change across the max lift point.

+$#>Description of Menu Items - DataBase

DataBase \ List .CVT Entries: Lists the current Concept Valve Train files stored In the selected database. The opened spreadsheet lists all entries in the currently selected database. The spreadsheet can be sorted and filtered to reduce the number of displayed entries and arrange the order in which they are listed. An entry in the database can be selected, (via the right mouse menu), and loaded into the application.

DataBase \ Rebuild .CVT Database Scratch File: Updates / creates the working database file. If a new database is to created or an existing one updated to reflect the addition of new files, this menu option will perform the necessary calculations and file creation such that the new or updated database is created.

DataBase \ .CVT DataBase Folder: This option allows the user to define the location of the required database. It should be the folder name which contains the individual Lotus software database folders. The Concept Valve Train database should be in a sub folder of this called ‘CAMPI’. Similar sub folders may exist for other licensed tools and programs produced by Lotus Engineering.

DataBase \ Valve Spring DataBase: This sub menu repeats the main .CVT database options but just for the valve spring data. A separate database structure allows valve springs to be stored and retrieved from this specific component database.

DataBase \ Data Spread-Sheet: This option opens the internal data spread sheet that can be accessed from any where in this application, (or Lotus Engine Simulation if open),. This multi shhet spread sheet can be used to manipulate and store data for transfer between files and/or separate parts of the interface. The alternative shortcut key combination Alt+F1 can be used throughout the interface where a specific ‘open’ menu is not available.

+$#>Description of Menu Items - Setup

Setup \ Start Options \ Toolbar Icons: Allows the user to choose between ‘standard’ and ‘mouse sensitive’ icons. A change to this setting will only take effect next time the application is started.

Setup \ Start Options \ Maximised: Defines whether on start up to open the main application window in its maximised (or full screen) condition.

Setup \ Start Options \ ‘Lotus’ Visibility: For users who do not wish for the Lotus Logo and images  to be visible or on any printouts this option enables the visibility status to be toggled on/off.

Setup \ ADAMS/Engine Launch Command: Opens a simple dialog box to enable the user to edit the command string used by the application when it attempts to open ADAMS/Engine View. This will need changing from the default value if you have ADAMS installed in a non-standard location, (i.e. not in C:\Program Files\ADAMS 11.0).

Setup \ ADAMS/Engine Default Template Folder: Opens a simple dialog box to enable the user to locate/edit the folder path used by default, for the location of the ADAMS/Engine templates that are supplied as part of the standard Lotus Concept Valve Train Install. This would normally be C:\Install Folder\AdamsEngine\Templates.tbl, where Install Folder is the folder name provided for the original install. 

Setup \ ADAMS/Engine Default SubSystems Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine subsystem files. This would normally be the ADAMS private database in C:\private.cdb\subsystems.tbl.

Setup \ ADAMS/Engine Default Profile Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine cam profile files. This would normally be the ADAMS private database in C:\private.cdb\cam_profile.tbl.

Setup \ ADAMS/Engine Default Cam Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine cam property files. This would normally be the ADAMS private database in C:\private.cdb\cams.tbl.

Setup \ ADAMS/Engine Default Plate Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine plate property files. This would normally be the ADAMS private database in C:\private.cdb\plates.tbl.

Setup \ ADAMS/Engine Default Spring Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine valve spring property files. This would normally be the ADAMS private database in C:\private.cdb\valve_springs.tbl.

Setup \ ADAMS/Engine Default Tappet Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine tappet property files. This would normally be the ADAMS private database in C:\private.cdb\tappets.tbl.

Setup \ ADAMS/Engine Default Valve Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine valve property files. This would normally be the ADAMS private database in C:\private.cdb\valves.tbl.

Setup \ ADAMS/Engine Default Rocker Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine rocker property files. This would normally be the ADAMS private database in C:\private.cdb\rockers.tbl.

Setup \ ADAMS/Engine Default Roller Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine roller property files. This would normally be the ADAMS private database in C:\private.cdb\rollers.tbl.

Setup \ ADAMS/Engine Default Pushrod Folder: Opens a simple dialog box to enable the user to locate/edit the default folder path used when writing/exporting ADAMS/Engine push rod property files. This would normally be the ADAMS private database in C:\private.cdb\rods.tbl.

Setup \ ADAMS/Engine Default Top Folder: Opens a simple dialog box to enable the user to locate/edit the default folder used as the ADAMS/Engine top level folder.

Setup \ Edit ADAMS/Engine Data Defaults: Opens a spread sheet that contains all the default data values that are used to populate the exported ADAMS/Engine property files that do not form part of the normal kinematics data entry. The display is given by component listing the current user value and the original default value.

Setup \ Include ADAMS/Engine Data Defaults in File: A toggle setting that when set will include the current values for ADAMS/Engine data variables in any saved data file.

Setup \ Include Limit ‘Settings’ in File: A toggle setting that when set will include the current values for the design limit data variables in any saved data file.

Setup \ Include ‘Spring Design’ Data in File: A toggle setting that when set will include the current values for the spring design section in any saved data file.

Setup \ Include ‘Valve/Piston Clr’ Data in File: A toggle setting that when set will include the current values for the valve to piston clearance section in any saved data file.

Setup \ Include ‘Overlap’ Data in File: A toggle setting that when set will include the current values for the overlap section in any saved data file.

Setup \ Include ‘Spring Dynamics’ Data in File: A toggle setting that when set will include the current values for the spring dynamics section in any saved data file.

Setup \ Exception Handler On: Toggles a trap for handling software crashes. This should be left ‘on’ as it provides a method by which any ‘crashes’ are trapped and managed such that whilst it will not prevent the application from failing, the failure will not impinge on any other open application or the operating system.

+$#>Description of Menu Items - Help

Help \ Contents: Opens this help file at the contents page.

Help \ Search for Help On: Opens this help file at the index page to allow the user to search the help file for references to a particular word or phrase.

Help \ How to Use Help: Opens the ‘how to use help’ help file at the contents page. This gives general tips and information about using on-line help files.

Help \ Display Bubble Help: Toggles the ‘bubble help’ visibility on/off. Bubble help displays a short description of a widgets action when the mouse is held over a widget, this can be annoying for experienced users hence the option is given to disable this. The visibility change will only take effect the next time the application is started.

Help \ About Lotus Concept Valve Train: Opens a dialog box that lists the current version details.

Help \ Help on Concept Valve Train: Opens this help file at the relevant page. The relevant page is taken as being the overview page for the current section.

+$#>Description of Right Mouse Menu Items

UnFix Point: This menu item is only available in the ‘Profile’ section. It allows the user to ‘free-up’ a previously defined point on the polynomial curve. It will unfix the nearest point and only for the derivative that selection was made on. If the pick is outside of a preset tolerance from the nearest point, then no action is performed. You will not be able to ‘unfix’ some of the points, for example lift at 0 degrees, as they are part of the minimum requirements for the curve definition.

Autoscale (Ctrl+A): Autoscales the currently displayed graph on which the right mouse click was made, such that all relevant portions of the graph are visible. This can also be achieved using the menu shortcut ‘Ctrl+A’ keyboard combination. 

Zoom: Allows the user to zoom into a specific region of a displayed graph or graphic. Both ‘pick hold down and drag a rectangle’ and ‘pick release drag and pick again’ styles are supported. A zoom is ignored if it does not stay within the bounds of a single graph or graphic.

Graph View: The relevant sub menu lists the available graph options for the current section.

Set Statics Graph Variables: This menu option has a sub-menu that lists the six statics analysis graphs, (position 1 to position 6). By selecting the required graph from the sub menu the settings for that graph position can be defined. This includes the plot type, i.e. line, bar or polar and the x and y axis variables.

Edit Axis Settings: Allows the user to edit the x and y axis settings, defining the axis start value, end value and step size. The position of right mouse click dictates the display to be edited.

List Line: Lists in a separate dialog box the x/y values for the line (or lines) on the selected graph. This option is not available for the ‘Mechanism’ and ‘Spring Design’ sections. The displayed text can be printed, saved to a file or ‘pasted’ into another application.

Dyn. Translate: This option is only available in the Mechanism section. It enables the dynamic view option allowing the user to translate the displayed graphics via the mouse ‘select’ ‘hold’ and ‘move’ process.

Dyn. Zoom: This option is only available in the Mechanism section. It enables the dynamic view option allowing the user to zoom the displayed graphics via the mouse ‘select’ ‘hold’ and ‘move’ process. The mouse movements down and up are interpreted as zooming ‘in’ and ‘out’.

Dyn. Rotate: This option is only available on the Mechanism section when in 3D mode. It enables the dynamic view option allowing the user to rotate the displayed mechanism model in 3D space via the mouse ‘select’ ‘hold’ and ‘move’ process. If the initial mouse selection is towards the edge of the displayed 

X-Y View: Lists in a separate dialog box the x/y values for the line (or lines) on the selected graph.

Flip Geometry about X value: Provides a simple method of modifying a mechanism’s geometry by mirroring them about a defined x-value. This can be used to transfer geometry from an inlet valve to an exhaust valve on a pent roof type cylinder head design.

Background Colour: Lists in a separate dialog box the x/y values for the line (or lines) on the selected graph.

+$#>Data Field Descriptions. - Profile Section:
 
Model Template(display only):  Sets the model type. Has fixed options from;
				Direct Acting
				Rocker – Centre Pivot
				Finger Follower – End Pivot
				Push Rod – Rocker
				Tappet - Rocker
The only way to change the template is to go through the ‘File \ New’ menu option

Motion Type: Defines which end of the system the polynomial motion is to be applied to. This can either be selected at the new file stage, or can be changed at a later stage via the selection box. Changing between cam motion and valve motion will result in the loss of any intermediate point definitions. This item is not selectable when the profile is defined by a list of points.

Profile Symmetry: Sets the symmetric nature of the polynomial curve. By default symmetry is set to symmetric, Changing to asymmetric will result in the loss of any intermediate point definitions. To have different opening and closing ramp properties will also require that the profile be identified as asymmetric. This item is not visible when the profile is defined by a list of points.

Point Spacing: The user can select an alternative increment between adjacent polynomial points for the listings and plots. The default is for 1.0 cam degree spacing. The following options are available;
				0.25 Degrees
				0.50 Degrees
				1.00 Degrees
				2.00 Degrees
				5.00 Degrees
This item is not selectable when the profile is defined by a list of points.

Max Lift (mm): Sets the maximum displacement, (i.e. zero degree point), for the mechanism end used for the polynomial definition. This is not editable when the profile is defined by a list of points.

Event Length Opening (deg): Defines the length in cam degrees of the opening half of the cam profile. That is from the top of the opening ramp to the maximum displacement point. For a symmetric profile this value will be used for both opening and closing sides. This item is not visible when the profile is defined by a list of points.

Event Length closing (deg): Defines the length in cam degrees of the closing half of the cam profile. That is from the maximum displacement point to the top of the closing ramp. This value is ignored and un-editable for a symmetric profile. This item is not visible when the profile is defined by a list of points.

Ramp Height Opening (mm): Defines the height in mm at the top of the opening ramp portion of the cam profile, that is the start of the main opening event. For a symmetric profile this value will be used for both opening and closing sides. This item is not visible when the profile is defined by a list of points.

Ramp Height Closing (mm): Defines the height in mm at the top of the closing ramp of the cam profile, that is at the end of the main event. This value is ignored and un-editable for a symmetric profile. This item is not visible when the profile is defined by a list of points.

Ramp Velocity Opening (mm/deg): Sets the velocity used in mm/deg for the constant velocity portion of the opening ramp. For a symmetric profile this value will be used for both opening and closing sides. This item is not visible when the profile is defined by a list of points.

Ramp Velocity Closing (mm/deg): Sets the velocity used in mm/deg for the constant velocity portion of the closing ramp. This value is ignored and un-editable for a symmetric profile. This item is not visible when the profile is defined by a list of points.

Ramp CA Period: Defines the length in cam degrees of the constant acceleration portion of the ramps, (the same value is applied to both opening and closing sides independent of the symmetry setting). Together with the ramp height and the ramp velocity this defines the ramp duration. This item is not visible when the profile is defined by a list of points.

Polynomial Exponents: Provides the default look-up table for polynomial exponents used in the polynomial curve segments. Each segment will use as many exponents as it needs based on the number of terms the segment requires. Each segment uses the same exponents table, (but will have unique coefficients). It is normal for the first two exponents to be 0 and 2, whilst the third varies from 6 through to 10. The others have a smaller effect and should increase from one to another. This item is not visible when the profile is defined by a list of points.

Segment Size: Defines the number of points to use in any curve smoothing or differentiation actions that need to be performed. Each derivative can have its own segment size. These items are not visible when the profile is defined by a polynomial, (maximum value 40).

Smoothing : Defines the smoothing value to apply to the given data. A zero implies no smoothing. Each derivative can have its own smoothing value. These items are not visible when the profile is defined by a polynomial, (maximum value is one less than the segment size).

+$#>Data Field Descriptions. - Mechanism Section:
 
Cam rotation direction: Sets the rotation direction for the camshaft as viewed within the graphic space, default clockwise.

Valve Angle (deg): Defines the angle of the valve rotated clockwise from the 12 o’clock position, (i.e. 0 is straight up).The default value varies with each template type.

Valve X axis intersect (mm): Sets the position of the valve axis by defining in global x-y the x distance of the valve from the global origin, (0.,0.). A positive value is a distance to the right of the origin whilst a negative value is to the left of the origin.

Follower Pivot (mm): Sets the x-y position of the rocker, (or follower), pivot point in the global x-y coordinate system. Conventional positive/negative directions apply. This does not have any relevance to the direct acting system template.

Follower Radii, Valve End (mm):	Sets the radius of the follower at the valve end of the system. It is at the point where the follower touches the valve tip and should always be a positive value. This does not have any relevance to the direct acting system template. This can be either a single radius value or for more advanced analysis a complete surface. To enable the ‘surface’ definition, select the small icon beside the value entry. This will then allow the surface to be defined via a set of angles and radii. The angles should vary from –ve through zero and positive. This mimics the data structure of a cam profile surface definition. The Zero angle is aligned as the contact point when on the base circle. The –ve angles are taken as towards the pivot point. An angular offset of the zero point can be defined via the ‘Advanced’ settings.

Follower Radii, Cam End (mm): Sets the radius of the follower at the cam end of the system. It is at the point where the follower touches the cam and should always be a positive or zero value, (a zero value implies a flat tappet and should only be used for the direct acting or push rod rocker templates).

Valve End Radius (rel) (mm): Defines the centre for the radius of the valve end side of the rocker, (or finger). The dimensions are local x-y dimensions that with due consideration to the rocker pivot and the remaining geometry attempt to build the system with the rocker/follower in contact with the cam base circle. These dimensions should be defined in conjunction with those for the cam end radius centre. These x-y dimensions have no relevance for the direct acting system. The default values in the templates should be studied to understand the sign convention and orientations.

Cam End Radius (rel) (mm): Defines the centre for the radius of the cam end side of the rocker, (or finger). The dimensions are local x-y dimensions that with due consideration to the rocker pivot and the remaining geometry attempt to build the system with the rocker/follower in contact with the cam base circle. These dimensions should be defined in conjunction with those for the valve end radius centre. These x-y dimensions have no relevance for the direct acting system. The default values in the templates should be studied to understand the sign convention and orientations.

Camshaft Centre, (mm): Sets the x-y position of the camshaft centre in the global x-y coordinate system. Conventional positive/negative directions apply. This does not have any relevance to the direct acting system template.

Push rod length, (mm): Defines the length between centers of the push rod, (should always be a positive number). It only applies to the push rod rocker template. The actual radii of the ball ends is not considered, but care should be taken to set the correct centre distance.

Cam Side Radius, (mm): Only applies to type 5. Defines the radius of the follower in contact with the tappet on the cam side of the rocker.

Tappet Length, (mm): Defines the length of the tappet for the push rod rocker template. This is the length from the cam surface to the lower push rod centre, (note that if the tappet has a radiused cam end the length is not that between centers but remains as the distance from the cam surface to the lower push rod centre along the tappet axis).

Cam Base Circle Radius, (mm): Sets the cam base circle radius dimension.

The following mechanism data variables are accessed through the ‘advanced’ button, (some can also be ‘edited’ or ‘joggled’).

Tappet-Valve offset, (mm): Sets the offset between the tappet and the valve axis for direct acting template types only. Would normally be set to zero.

Valve Tip Radius, (mm): Defines the radius on the valve tip for finger or rocker type templates. This value should be positive, or zero for a ‘flat’ tip.

Valve Tip Radius offset, (mm): Sets the offset between the valve tip radius centre and the valve centre line. Would normally be set to zero.

Valve Tip Chamfer, (mm): Sets the value for the chamfer at the top of the valve. Effects the valve tip contact stress calculation.

Follower Crown/Roller Barrel Radius, (mm): This value either defines that a follower has a spherical crown, or sets the ‘barrel’ radius on a cylindrical follower. The sequence is that if the cam end follower radius is set to zero, then this value defines a spherical radius for the follower. If however the cam end follower radius is set to some positive value then this radius will define the ‘barrel’ radius along the axis of the roller/follower.

Crown Radius Offset, (mm): Defines the value for the offset between the crown radius and the follower axis, (normally zero).

Cam to Follower Offset, (mm): Offset between the cam centre line and the follower offset, (normally zero).

Cam to Follower Clearance, (mm): An optional clearance value that can be used to create a difference between the cam and valve motion, defined as at the cam position, (normally set to zero).

Valve Tip Clearance, (mm): An optional clearance value that can be used to create a difference between the cam and valve motion, defined as at the valve tip position, (normally set to zero).

Valve Train Initial Compression, (mm):	Defines an initial deflection of the system, (normally set to zero).

Tappet Angle, (deg): Sets the angle of the tappet axis in the global coordinate system. The angle is +ve rotated clockwise from the 12 o’clock position, (i.e. 0 is straight up).

Tappet Working Diameter, (mm): Defines the actual working diameter of the tappet surface. This is used to modify the effective line contact width used in the contact stress calculations, it is currently only used on the flat tappet calculations.

Tappet Axial Offset, (mm): Defines the distance along the camshaft axis that the lobe centre is offset relative to the tappet centre. This is used to modify the effective line contact width used in the contact stress calculations, it is currently only used on the flat tappet calculations.

Tappet Radial Offset, (mm): Defines the distance perpendicular to the camshaft axis that the lobe centre is offset relative to the tappet centre. This is used to modify the effective line contact width used in the contact stress calculations, it is currently only used on the flat tappet calculations.

+$#>Data Field Descriptions. – Static’s Section:
 
Outer Spring Preload (N): Sets the spring pre-load for the outer spring. If a variable rate spring is selected for the outer spring, this data entry is ‘disabled’ and ignored. The outer spring will be ignored if both its fitted load and rate are zero.
 
Inner Spring Preload (N): Sets the spring pre-load for the inner spring. If a variable rate spring is selected for the inner spring, this data entry is ‘disabled’ and ignored. The inner spring will be ignored if both its fitted load and rate are zero.

Outer Spring Rate (N/mm): Defines the linear spring rate for the outer spring. If a variable rate spring is selected for the outer spring, this data entry is ‘disabled’. The outer spring will be ignored if both its fitted load and rate are zero. If a variable rate spring is selected, the spring is defined as a series of load points, the user defining load against lift from the fitted condition. Thus the first load point should be at zero lift and be the fitted load, (entering only two points equates to a linear rate spring).

Inner Spring Rate (N/mm): Defines the linear spring rate for the inner spring. If a variable rate spring is selected for the inner spring, this data entry is ‘disabled’. The inner spring will be ignored if both its fitted load and rate are zero. If a variable rate spring is selected, the spring is defined as a series of load points, the user defining load against lift from the fitted condition. Thus the first load point should be at zero lift and be the fitted load, (entering only two points equates to a linear rate spring).

Design Speed (rpm): Sets the engine speed for which the ‘static’s’ calculations are performed at, (note this assumes a four stroke cycle and the camshaft is running at half this engine speed.

System Effective Mass (kg): The static’s calculations that require mass, (i.e. inertia load), use this effective mass value. The mass should be the effective mass at the valve, (i.e. the position in the system of the spring load). Thus all valve train components need to be referred relative to the valve axis. Rocker rotational inertia’s must be the linear equivalent and cam side push rod parts need to take the rocker ratio in account. This can be either entered in as a single value by selecting the EFF button next to the value entry. Alternatively selecting the COMP button enables a data entry dialogue box where mass properties are added by component. This aligns the mass properties with the ADAMS/Engine export files, where mass properties are by component. Some components such as rockers will require inertia values rather than mass values. Variations in effective mass due to rocker ratio changes can be viewed as one of the static analysis results.

Cam Face Width (mm): Sets the cam face width.

Cam Poisson’s Ratio: Sets the Poisson’s ratio for the camshaft material. This is used in the Hertzian contact stress and oil film calculations.

Cam Young’s Modulus (N/mm2): Sets the Young’s modulus value for the camshaft material. This is used in the Hertzian contact stress and oil film calculations.

Follower Poisson’s Ratio: Sets the Poisson’s ratio for the follower material. This is used in the Hertzian contact stress and oil film calculations.

Follower Young’s Modulus (N/mm2): Sets the Young’s modulus value  for the follower material. This is used in the Hertzian contact stress and oil film calculations.

Coefficient of Sliding Friction: Defines the value used for sliding friction in the cam drive torque calculations. All drive torque calculations assume that the follower is a sliding contact and not a rolling contact. To indicate a rolling contact the coefficient should be set to zero. 
The following data items are accessible through the ‘advanced’ button.

Dynamic Viscosity, (Pa.s): Defines the average oil dynamic viscosity of the lubricant at the surface temperature of the follower. (used for the oil film calculations). The default value is 0.0075 Pa.s, with typical range being 0.01 to 0.005.

Pressure Coefficient of viscosity, (1/Pa): Defines the coefficient used for the assumed exponential relationship of the variation of viscosity with pressure. The default value is 2.198E-8, Pa-1 , with the typical range being 1.5E-8 to 2.5E-8.

Cam RMS Surface Roughness, (m): Defines the cam surface roughness. Default value 2.5E-7 m.

Follower RMS Surface Roughness, (m): Defines the follower surface roughness. Default value 2.5E-7 m.

+$#>Data Field Descriptions. – Valve/Piston Clearance Section:

Valve Lift Origin: Defines the origin of the valve lift data. This can be either the current profile, (i.e. the valve motion currently defined in the profile section of Concept Valve Train), or one of the valves currently defined in the engine simulation model, (note that this may not be enabled if the engine simulation module is not licensed or no poppet valve elements exist in its current model), or a user specified list of valve lift against angle. The user specified lift angles should be defined in terms of cam angle where 0 is the mop point.

Valve Type: Defines whether the valve is an inlet or an exhaust valve. This is used together with the valve timing to correctly phase the valve lift with respect to the piston motion.

Valve MOP (deg): Sets the valve timing in crank degrees. This is used together with the valve timing to correctly phase the valve lift with respect to the piston motion. The sign for this data value is ignored, as the sign is assumed based on the valve type, where an Inlet is assumed to be positive and exhausts negative.

Engine Geometry Origin: This identifies how the engine geometry, (Rod length and stroke), are obtained. This can either be user defined and entered accordingly or one of the cylinders currently defined in the simulation model, (note that this may not be enabled if the engine simulation module is not licensed or no cylinder elements exist in its current model)

Rod Length, (mm): Sets the connecting rod length used for calculating piston motion. This is the distance between the big and little end centers.

Stroke, (mm): Sets the crankshaft stroke used for calculating piston motion.

Valve Angle, (deg): Defines the angle of the valve relative to the cylinder bore.

Perpendicular Distance to Piston, (mm): Defines the perpendicular distance of the lowest point of the valve when on its seat to the piston crown when the piston is at top dead centre. This is used as the start point clearance from which valve and piston motion is subtracted from and added to.

+$#>Data Field Descriptions. – Spring Design Section:

Maximum Lift, (mm): Sets the maximum valve lift that the spring design is to accommodate.

Maximum Lift Load, (N): Defines the required valve spring load at the maximum lift point.

Intermediate Lift, (mm): Sets the position of an intermediate lift point at which you can define the spring load deviation from the nominal linear rate.

Delta Load from Linear, (N): Controls the deviation from the nominal linear rate by specifying the difference in spring load at the intermediate point from that which the nominal rate would achieve. Thus specifying a delta of zero produces a linear rate spring. Typical values for automotive valve springs are 3 – 8 N.

Wire CSA Type: Sets the type of wire cross section to use. Can be round, elliptical, square or rectangular. Depending on the wire CSA type selected will dictate whether one or two values are required to set the section size. For non-round/non-square wire a default aspect ratio is used. This default ratio can be edited through the ‘advanced’ button.

The following data items are grouped in pairs, where the user can only define one item in each pair. This provides alternative ways of defining the spring design based on the users own restrictions or requirements.

Stress at Maximum Lift, (N/mm2): This item is grouped with the data item ‘wire diameter’, (see below). This allows the user to control the spring wire size either by defining the allowable wire stress at the maximum lift point, or by defining the wire diameter directly and calculating the stresses.

Wire Diameter, (mm): This item is grouped with the data item ‘stress at maximum lift’, (see above). This allows the user to control the spring wire size by directly defining the wire diameter (or length), or by controlling the wire diameter through defining the wire stress at the maximum lift point. For the cases of elliptical or rectangular wire a second diameter (or length) is required to set the wire section dimension along the spring axis. Where the user has chosen to define wire size by ‘stress at maximum lift’ then the default aspect ratio is used to control the 2nd section dimension.

Inner Diameter, (mm): Sets the diametral space allowed for the spring by defining the inner diameter of the spring. This is grouped with the data item ‘outer diameter’ where the spring can be defined by either the inner or the outer diameter.

Outer Diameter, (mm): Sets the diametral space allowed for the spring by defining the outer diameter of the spring. This is grouped with the data item ‘inner diameter’ where the spring can be defined by either the inner or the outer diameter.

Stress Range, (N/mm2): This item is grouped with the data item ‘fitted load’ and provides the alternative ways of setting the fitted load. The user can define the fitted load through setting the stress range allowed between the fitted length and the maximum lift points. For an automotive valve spring using shot peened wire a typically value is 500 N/mm2.

Fitted Load, (N): This item is grouped with the data value ‘stress range’ and provides the alternative ways of setting the spring fitted load. This value sets the fitted load directly, the stress range and rate thus being calculated based on the two fixed load points and fitted and maximum lift, (see also stress range above).

Clearance at Maximum Lift, (mm): This item is grouped with the data value ‘fitted length’ to provide the alternative ways of setting the spring fitted length. This value sets the difference between the length at the maximum lift point and the length at the maximum solid point. For typical automotive tolerances this should be as a nominal dimension in the range 1.5 to 1.0. Defining the fitted length via the clearance means that the fitted length is a derived value.

Fitted Length, (mm): This item is grouped with the data value ‘clearance at maximum lift’ to provide the alternative ways of setting the spring fitted length. This value defines the fitted length directly. By defining the spring fitted length directly it is possible to set a value for the fitted length that will not allow a spring to accommodate the required maximum valve lift, in this instance the defined fitted length is ignored and set to the minimum possible value. (i.e. maximum solid length + maximum valve lift).

The following data items are accessible through the ‘advanced’ button.

Spring Wire Density, (kg/m3): Defines the wire density value used to estimate the mass of the spring. The default value is 7800 kg/m3.

Wire Modulus of Rigidity, (N/mm2): Defines the value of modulus of rigidity used within the spring calculations. The default value is 79300 N/mm2.

Wire Aspect Ratio for Non-round, (B/A): Defines the ratio used to set the 2nd diameter or length needed with elliptical or rectangular wires. For user defined wire size this values is ignored The default value is 0.8.

+$#>Data Field Descriptions. – Overlap Section:

The following data variables are duplicated for both the inlet and exhaust valves.

Valve Lift Origin, (choice): Select from one of the available options the location of the valve lift data.

1)	Current Profile: Uses the currently held profile data for the lift definition.
1)	Simulation Valve: Uses a valve from the current engine simulation model as hw source of the lift data. Choose from the available inlet/exhaust valves (as appropriate) for the source of lift data. For this option an additional selection box is enabled.
1)	Saved File: Uses a saved Concept Valve Train data file as the source of the lift data. For this option an additional text entry box and browse icon is enabled.
1)	User Specified: Uses the user defined data as the source for the valve lift data. The x values for angle should be in cam degrees with 0 as the maximum lift point and –ve angles as the opening side. For this option an additional edit box icon is enabled.

MOP, (deg): Defines the maximum opening point timing value for the profile. This value is in crankshaft degrees. It will force a +ve value for the inlet and a –ve value for the exhaust. Selecting a ‘Simulation valve’ will automatically update this value to be the same as in the engine simulation model.

Opening Clearance, (mm): Defines the valve clearance to be applied to the opening side of the valve lift. This is used in conjunction with the closing clearance to convert the ‘defined lift’ into the ‘corrected lift’ by subtracting the incremental clearance value. Selecting a ‘Simulation valve’ will automatically update this value to be the same as in the engine simulation model, it will also be ‘grayed’ out for a simulation valve as these are normally already corrected for clearance.

Closing Clearance, (mm): Defines the valve clearance to be applied to the closing side of the valve lift. This is used in conjunction with the opening clearance to convert the ‘defined lift’ into the ‘corrected lift’ by subtracting the incremental clearance value. Selecting a ‘Simulation valve’ will automatically update this value to be the same as in the engine simulation model, it will also be ‘grayed’ out for a simulation valve as these are normally already corrected for clearance.

+$#>Data Field Descriptions. – Dynamic Analysis Section - Model:

The dynamic model is made up of a series of generic mass elements and generic link elements together with some specific additional elements such as gas spring and hydraulic tappet. Each element type will be reviewed separately below.

Each element in the model is identified by a description that includes both a number and short text description, i.e. ‘System mass2 (Retainer Mass)’, this should assist in selecting the relevant element from the element selection box. The currently listed element will be highlighted in red on the graphical display. Alternatively the required element to view/modify the properties for can be picked with the cursor directly from the graphical display.

General Model Properties

Preload, (N) [spring 1]: Sets the preload for spring 1

Preload, (N) [spring 2]: Sets the preload for spring 2

Preload, (N) [Hyd_Tappet]: Sets the preload for the internal spring of the hydraulic tappet element.

Preload, (N) [Check_Valve]: Sets the preload for the ball check valve of the hydraulic tappet model.

Preload, (N) [CPS-Outer]: Sets the preload for the lost motion spring contained in the outer tappet of CPS model.

Mass Element Properties

Mass elements have two properties one of which is compulsory (mass) and the second of which is optional (guide damping).

Mass, (g): Defines the mass of the element. Where relevant this should be the summation of a number of components, (such as system mass 2 which is the combination of retainer, collets and a portion of the valve) or a portion of a single component, (i.e. system mass 3 the valve head which is a portion of the total valve mass).

Guide Damping, (N.s/m): Defines the damping value applied to the mass element. This is the damping between the mass element an ‘earth’ or ‘ground’ reference point. Thus the velocity used in the damping calculation is the absolute value rather than any relative value. This needs to be considered since not all mass elements have a direct connection to earth, a conventional retainer mass element is an example of this.

Linkage Element Properties

Link elements have different property requirements depending on the basic link type chosen. Five link types are available;

1) Dual Rate
2) Adams Impact Contact
3) Eccentricity Based (lift)
4) Eccentricity Based (Ecc)
5) User Subroutine

The properties for each link type are listed individually below.

1) Dual Rate

The dual rate link element consists of two linear spring damper elements, each spring-damper having its own individual clearance value. The first spring-damper can stiffness can be varied linearly with deflection via a rate coefficient term.

Primary Linear Stiffness, (N/mm): Defines the stiffness of the first (or primary) spring component for the link.

Primary Rate Change, (N/mm/mm): Defines the rate of change in the primary stiffness rate. Used to provide a link whose stiffness can increase (or decrease) with change in length. Setting this to zero infers a linear rate primary spring.

Primary Viscous Damping, (N.s/m): Defines the damping value for the first (or primary) damper component of the link.

Primary Clearance, (mm): Sets the clearance value for the primary link. Defines the amount of displacement will occur between the connected masses before the primary spring-damper is included. By definition links that can define a clearance are allowed to separate. Should separation not be allowed for a link then this data entry will be greyed out.

Secondary Clearance, (mm): Sets the clearance value for the secondary link. Defines the amount of displacement that will occur between the connected masses before the secondary spring-damper is included. A secondary clearance value does not imply that the spring-damper can separate.

Secondary Stiffness, (N/mm): Defines the stiffness of the second (or secondary) spring component for the link.

Secondary Viscous Damping, (N.s/m): Defines the damping value for the second (or secondary) damper component of the link.

2) Adams Impact Contact

The Adams impact contact link element consists of a force term and a damping term. The formulation follows that used within Adams/Engine to use coefficients and exponents to prescribe the force in the link.

Stiffness [k], (N/mm): Defines the stiffness coefficient of the contact force formulation for the link.

Force Exponent [e], (-): Defines the force exponent of nte contact force formulation The force exponent is typically larger than 1.

Max. Damping [cmax], (N.s/m): Defines the damping coefficient of the contact force formulation for the link.

Primary Clearance, (mm): Sets the clearance value for the primary link. Defines the amount of displacement will occur between the connected masses before the primary spring-damper is included. By definition links that can define a clearance are allowed to separate. Should separation not be allowed for a link then this data entry will be greyed out.

Penetration Depth [d], (mm): Defines the penetration depth of the contact force formulation for the link.

Scale Factor [s], (-): Defines the scale factor of the contact force formulation for the link.

3) Eccentricity Based (lift)

The eccentricity based links provided an element the properties of which are based on two spring-dampers acting in parallel, (similar to type 1). The difference from type 1 is that the change in primary stiffness rather than changing with compression of the link, is based on the passed value of eccentricity. This restricts its use to System Link 1 the camshaft contact link. The difference between this type 3 and type 4 is in how the secondary clearance value is interpreted. For type 3 it is taken as a compression distance, whilst for type 4 it is taken as an eccentricity amount.

Primary Linear Stiffness, (N/mm): Defines the stiffness of the first (or primary) spring component for the link.

Primary Rate Change, (N/mm/mm): Defines the rate of change in the primary stiffness rate. Used to provide a link whose stiffness can increase (or decrease) with passed eccentricity value. Setting this to zero infers a linear rate primary spring.

Primary Viscous Damping, (N.s/m): Defines the damping value for the first (or primary) damper component of the link.

Primary Clearance, (mm): Sets the clearance value for the primary link. Defines the amount of displacement will occur between the connected masses before the primary spring-damper is included. By definition links that can define a clearance are allowed to separate. Should separation not be allowed for a link then this data entry will be greyed out.

Secondary Clearance (lift), (mm): Sets the clearance value for the secondary link. Defines the amount of displacement that will occur between the connected masses before the secondary spring-damper is included. A secondary clearance value does not imply that the spring-damper can separate.

Secondary Stiffness, (N/mm): Defines the stiffness of the second (or secondary) spring component for the link.

Secondary Viscous Damping, (N.s/m): Defines the damping value for the second (or secondary) damper component of the link.

4) Eccentricity Based (Ecc)

See discussion for type 3 above.

Primary Linear Stiffness, (N/mm): Defines the stiffness of the first (or primary) spring component for the link.

Primary Rate Change, (N/mm/mm): Defines the rate of change in the primary stiffness rate. Used to provide a link whose stiffness can increase (or decrease) with passed eccentricity value. Setting this to zero infers a linear rate primary spring.

Primary Viscous Damping, (N.s/m): Defines the damping value for the first (or primary) damper component of the link.

Primary Clearance, (mm): Sets the clearance value for the primary link. Defines the amount of displacement will occur between the connected masses before the primary spring-damper is included. By definition links that can define a clearance are allowed to separate. Should separation not be allowed for a link then this data entry will be greyed out.

Secondary Clearance (lift), (mm): Sets the clearance value for the secondary link. Defines the amount of eccentricity before the secondary spring-damper is included. A secondary clearance value does not imply that the spring-damper can separate. Only the magnitude of the eccentricity is used its sign being ignored.

Secondary Stiffness, (N/mm): Defines the stiffness of the second (or secondary) spring component for the link.

Secondary Viscous Damping, (N.s/m): Defines the damping value for the second (or secondary) damper component of the link.

Hydraulic Tappet (Internals) - Properties

The hydraulic tappet internals element models the response of the oil column of the hydraulic tappet. This link element includes the effect of leakage through the clearance, flow through the check valve, oil properties including aeration and the external supply pressure.

Ball Radius, (mm): Sets the radius of the ball used in the check valve within the hydraulic tappet. Whilst its mass is defined separately as a lumped mass its radius is required for the check valve oil flow calculations.

Passage Height, (mm): Together with passage length (see below) define the equivalent leakage area from the high pressure region of hydraulic tappet.

Passage Length, (mm): Together with passage height (see above) define the equivalent leakage area from the high pressure region of hydraulic tappet.

Ball Travel, (mm): Defines the limit of travel for the check valve ball. Controls how far the ball will move before touching the separately defined mechanical stop. The amount of ball travel is used within the oil flow calculation.

Check Valve Open Radius, (mm): Defines the radius of the check valve hole. Since closed by the check valve ball this value obviously needs to be less than the radius of the check valve ball. In combination with the other properties controls the oil flow through the check valve.

Supply Pressure Limiting Lift, (mm): Sets the tappet lift beyond which the supply pressure is switched ‘off’. This is to mimic the action of alignment between the oil supply hole and the groove in a direct acting tappet.

HPC Initial Volume, (mm3): Defines the oil volume of the high pressure region of the tappet. This is used as part of the oil stiffness and change in volume calculations.

Piston Radius, (mm): Sets the radius of the hydraulic tappet internal piston. This defines the high pressure region effective area used with the calculated internal 

Hydraulic Tappet (Internals) - Oil Properties

A collection of properties that define the characteristics of the hydraulic tappet oil.

Oil Viscosity (Dynamic), (cP): Defines the viscosity of the oil in centi-poise. Typical values are 4 – 7 cP.

Oil Density, (kg/m3): Defines the oil density. Typical value is 900 kg/m3.

Air Volume Fraction, (%): Sets the fraction of air by volume in the hydraulic tappet oil.

Oil Bulk Module, (N/mm2): Defines the bulk module of the oil. Typical value is 2000 N/mm2.

Oil Pressure Coefficient, (-): Used in the calculation of oil properties, typical value 0.0001

Reference Pressure, (N/mm2): Defines the reference pressure used within the oil property calculations. This is take na s the pressure for which all relevant parameters are defined.

Hydraulic Tappet (Internals) - Flow Coefficients

Calculations for flow both through the check valve and past the clearances are based not only on geometry but use a number of empirical coefficients. These coefficients are edited through the pop-up dialogue box.

CV1, (-): Check valve flow coefficient 1, typical value 2300

CV21, (-): Check valve flow coefficient 2, typical value 0.00001

CV22, (-): Check valve flow coefficient 3, typical value 0.00001

CV3, (-): Check valve flow coefficient 4, typical value 0.5

Reynolds Switch, (-): Controls the switch between alternative algorithms using a Reynolds No. based criteria. Typical value 2.3

C1, (-): High pressure leakage coefficient 1, typical value 0.5235

C2, (-): High pressure leakage coefficient 2, typical value 1.0

C3, (-): High pressure leakage coefficient 3, typical value 1.0

C4, (-): High pressure leakage coefficient 4, typical value 3.0

Hydraulic Tappet (Internals) - Supply Pressure

Calculations for flow into the tappet from the supply are calculated with respect to a current supply pressure. The supply pressure can be defined as a lookup table that varies with engine speed. Linear interpolation/extrapolation is used to identify pressure at intermediate points.

Engine Speed, (rpm): Sets the engine speed point for defined pressure value. 

Pressure, (N/mm2): Sets the oil supply pressure to the tappet for this particular engine speed point.

Gas Spring - Properties

The gas spring element is used instead of a conventional multi-mass coil spring. It is represented by a series of pressurized chambers connected by controlled orifices. Properties required include the geometric definition of the component as well as the properties of the gas being used within the pneumatic spring.

Internal Spring Diameter, (mm): Sets the internal diameter of the air spring, it is used together with the calculated internal pressure to determine the gas spring force.

Internal Spring Volume, (mm3): Defines the internal volume of the gas springs pressurized region.

Wall Thickness, (mm): Sets the wall thickness of the gas spring. Used in the heat transfer calculation.

Inner Wall Temperature, (C): Defines the inner wall temperature of the gas spring. Used in the heat transfer calculation.

Spring Gas Type, (Choice): Select the required gas to fill the spring from Nitrogen, Air or User defined. For a user defined gas an additional button is displayed to enable the user to edit the mole fraction composition of the user defined gas.

Gas Spring – Properties – Orifice and Internal Stop

The properties for the supply orifice and internal stop are accessed through a separate dialogue box.

Orifice Diameter, (mm): Defines the diameter of the supply orifice. The nominal diameter is modified b y the associated CF values to calculate effective flow areas In the forward and reverse directions.

CF Value, (Spring to Supply): Defines the CF value through the supply orifice for flow in the direction from the spring volume to the reservoir. Can be used together with the value below to provide directionality on orifice flow.

CF Value, (Supply to Spring): Defines the CF value through the supply orifice for flow in the direction from the reservoir to the spring volume. Can be used together with the value above to provide directionality on orifice flow.

Internal Stop Travel Limit, (mm): Sets the limit of travel for the gas spring before the mechanical stop is included in the mass spring system. This value would normally be set as greater than the maximum lift and as such the internal stop should play no part in the dynamic analysis calculations except for large levels of valve float.

Internal Stop Damping, (N.s./m): Sets the damping value for the gas spring’s internal stop spring damper link.

Internal Stop Linear Rate, (N/mm): Sets the stiffness value for the gas spring’s internal stop spring damper link.

Internal Stop Rate Change, (N/mm/mm): Sets the rate of change in the stiffness value for the gas spring’s internal stop spring damper link. Setting this value to zero will equate to a linear rate spring.

Gas Spring – Properties – By Pass Valve Data

The properties of the by-pass valve are accessed through a separate dialogue box.

ByPass Ball Radius, (mm): Sets the radius of the ball used in the bypass valve within the gas spring. The bypass valve is a pressure limiting device that would not normally be acting in a cyclic manner, but is primarily a design requirement to avoid the possibility of hydraulicing with cumulative oil build up. Thus the bypass valve would normally be expected to remain closed for a dynamic simulation.

ByPass Opening Radius, (mm): Defines the radius of the bypass valve hole. Since closed by the bypass valve ball this value obviously needs to be less than the radius of the bypass valve ball. In combination with the other properties controls the gas flow through the bypass valve.

ByPass Spring Preload, (N): Sets the spring preload used for the closing spring of the bypass valve.

ByPass Spring Rate, (N/mm): Sets the spring rate used for the closing spring of the bypass valve.

ByPass Ball Travel, (mm): Defines the limit of travel for the bypass valve ball. Controls how far the ball will move before touching the separately defined mechanical stop. The amount of ball travel is used within the gas flow area calculation.

ByPass Ambient Temperature, (C): Sets the assumed ambient temperature for the gas contained in the bypass chamber.

ByPass Ambient Pressure, (N/mm2): Sets the assumed ambient pressure for the gas contained in the bypass chamber.

CF Value, (Spring to ByPass): Defines the CF value through the bypass orifice for flow in the direction from the spring volume to the bypass ambient volume. Can be used together with the value below to provide directionality on bypass orifice flow.

CF Value, (ByPass to Spring): Defines the CF value through the bypass orifice for flow in the direction from the bypass ambient volume to the spring volume. Can be used together with the value above to provide directionality on bypass orifice flow.

Gas Spring – Properties – Seal Leakage Data

The properties of the leakage from the gas spring are accessed through a separate dialogue box. The leakage is primarily at the seal area, if multiple leakage areas are envisaged they will need to be defined as a single ‘effective’ leakage.

Leakage Area, (mm2): Defines the effective leakage area. Should include any leakage sites envisaged as a single effective number.

Leakage Ambient Temperature, (C): Sets the assumed ambient temperature for the gas contained in the bypass chamber.

Leakage Ambient Pressure, (N/mm2): Sets the assumed ambient pressure for the gas contained in the bypass chamber.

CF Value, (Spring to Leakage): Defines the CF value through the leakage area for flow in the direction from the spring volume to the leakage ambient volume. Can be used together with the value below to provide directionality on leakage flow.

CF Value, (Leakage to Spring): Defines the CF value through the leakage area for flow in the direction from the leakage ambient volume to the spring volume. Can be used together with the value above to provide directionality on leakage flow.

Gas Spring Properties - Supply Data

Calculations for flow into the gas spring from the supply are calculated with respect to a current supply pressure and temperature. The supply pressure and temperature can be defined as a lookup table that varies with engine speed. Linear interpolation/extrapolation is used to identify values at intermediate points.

Engine Speed, (rpm): Sets the engine speed point for defined pressure and temperature values.

Pressure, (N/mm2): Sets the gas supply pressure to the spring for this particular engine speed point.

Temperature, (C): Sets the gas supply temperature to the spring for this particular engine speed point.

Gas Spring Properties – User Gas Properties

For user defined gases the composition in terms of the mole fraction must be specified. Mole fraction no’s are in the range 0-1 the sum of which must equal 1.0 The 11 gases considered are;

Carbon dioxide, (CO2): 
Carbon monoxide, (CO): 
Water, (H2O): 
Molecular Hydrogen, (H2): 
Molecular Oxygen, (O2): 
Molecular Nitrogen, (N2): 
Atomic Oxygen, (O): 
Atomic Hydrogen, (H): 
Atomic Nitrogen, (N): 
Nitric Oxide, (NO): 
Argon, (Ar): 

+$#>Data Field Descriptions. – Dynamic Analysis Section - Profile:

The input(s) motion to the dynamic model can come from a variety of sources. This data panel section defines the source of these inputs. Normally only one profile source requires to be defined, with a CPS model two profiles are required, one for the Inner and one for the outer. The following menu items are repeated should the dynamic model include the CPS element.

A profile input has a global on/off check box. Unless this is checked no input motion will be applied irrespective of the specific data settings, (for the CPS element the upper data is applied to the inner tappet).

The profile source has four options;

Current Profile: Sets the profile source as that currently contained in the ‘profile’ section. The current profile option requires the user to define the valve MOP to enable correct timing of the lift. MOP values are in crank degrees and would normally be +ve for an inlet and –ve for an exhaust.

Simulation Valve: Sets the profile source as a particular simulation model from the currently loaded engine simulation valve. If no engine model is currently loaded, or the current model doesn’t have any valves or you are not licensed to use the engine simulation module this option will be greyed out.

Saved File: Sets the profile source as a previously saved text file. The data in this file should be in 4xcolumn format, with columns separated by spaces or commas. The first column should be angle (cam deg), then lift(mm), velocity (mm/deg) and acceleration (mm/deg2). A fifth column if present, (i.e. Jerk), will simply be ignored. 

User Specified: Sets the profile source as being a user specified list. The user list has the advantage over the previous item in that it remains saved as part of the input data file rather than a separate file, hence leading to greater data control. To enter a user specified lift once the check box has been selected pick the edit button to display a conventional data list editor. This data list can be pre-filled from the current profile by selecting the appropriate toggle switch. Note that two different interpolation types are available for use with user defined lift.

Pre Fill with Current: A utility function to assist in pre-filling a user list with the current profile.
It is only enabled when ‘User Specified’ lift is selected.

Linear Interpolation: For user specified lift this sets the interpolation type when looking up data values to be linear. This option is only enabled when ‘User Specified’ lift is selected.

Fitted Polynomial: For user specified lift sets the interpolation type to be a polynomial fit. This provides a degree of smoothing for both measured and/or sparse data. This option is only enabled when ‘User Specified’ lift is selected.

With the CPS tappet the above data block is repeated for the outer tappet. As with the inner tappet the check box ‘Set CPS Outer Profile Data Origin’ must be check to apply any motion to the outer tappet.

+$#>Data Field Descriptions. – Dynamic Analysis Section - Gas:

Gas pressure can be optionally applied to the port side of the dynamic model and the cylinder side of the dynamic model. These gas loads are applied to either side of the valve head mass, being updated at each calculation increment, the values normally being identified by interpolation of the supplied data.

No gas force is applied to the port side of the valve head until the Set Port Side Gas Data check box is selected.

The gas load source has three options;

Simulation Port: Select the required port from the current LES simulation model. This selection box will be empty if no simulation model is loaded or the model currently contains no ports. The list consists of one entry for each port for each prs results file currently loaded. Thus is no prs results are currently loaded in the LES results viewer this list will again be empty irrespective of how many ports are in the model.

Saved File: Sets the gas side source as a previously saved text file. The data in this file should be 2xcolumn format, with columns separated by spaces or commas. The first column should be crank angle in degrees (0-720) and the second column should be pressure in bar. Use the browser option to locate the required file.

User Specified: Sets the gas load source as being a user-defined list. As with the profile the advantage of the user list is that it remains with the data file and hence assists in retaining data integrity. An option exists to pre-fill the user list from the currently selected simulation port. This provides then an automatic way of stripping the gas pressure data from the prs file and saving it with the Valve Train model file. To edit the list select the editor button which opens the standard numerical list editor window.

Eff. Area (mm2): This defines the effective area of the port side, over which the incremental gas pressure is applied. If this number is left as zero no force is applied. An convenience calculation utility is provided that calculates and fills this value box, based on the current relevant Adams subsystem values.

Pre-fill User from Selection: As covered above this option is enabled when the source type is set to ‘Simulation Port’ and a ports prs file has been selected. This option will copy the current selection to the user list and change the source type to ‘User Specified’.

Linear Interpolation: Together with the option below, defines whether the calculation time steps will use linear interpolation between data points or a polynomial curve to find the required pressure values.

Fitted Polynomial: As for the option above, defines whether the calculation time steps will use linear interpolation between data points or a polynomial curve to find the required pressure values.

No gas force is applied to the cylinder side of the valve head until the Set Cylinder Side Gas Data check box is selected.

As for the Port Side, the gas load source has three options. These options are identical to the port side with the exception that the list of current elements is cylinders rather than ports. The effective area calculation is also slightly different being based purely on the valve head size currently in the Adams subsystem.

+$#>Data Field Descriptions. – Dynamic Analysis Section - Run:

This section defines what analysis run is performed and how the run proceeds. Run times are reduced if the calculations are performed in ‘batch’ mode compared to the default ‘interactive’ mode. But the visual feed-back of the job progress is lost. Five different run types are provided that covers the likely range of analysis tasks from a single fixed speed to a transient run.

Run Type: Sets the type of calculation run type as either Interactive (default) or Batch. When in interactive mode the screen graphical display is updated to illustrate the calculated dynamic response including all current defined results traces. If run in ‘Batch’ mode the graphics are not updated which results in a faster run time. For the Batch mode a progress bar is displayed to indicate the status of the run and provided a ‘cancel’ function.

Solve Type: Sets the solution type. Depending on the solution type selected the run definition variables will change. This is indicated by ‘greying’ out the non-relevant variables. The solution types are;

Run to Time: A constant speed (or constantly varying speed) run, whose run length is defined by time in seconds. The run is stopped when the defined amount of time has elapsed.
Run to Cycles: A constant speed (or constantly varying speed) run, whose run length is defined by the number of cycles. The run is stopped when the defined number of cycles is reached, a cycle being defined as 360 cam degrees.
Run to Speed: A varying speed run, whose run length is defined by a combination of the start speed, target speed and the speed change value. The run is stopped when the target end speed is reached.
Staircase Speed x Time: Defines a run having a series of discreet constant speed values, the duration of each speed run being dictated by time in seconds. The run is stopped when the end speed step has been reached and the defined amount of time has elapsed.
Staircase Speed x Cycles: Defines a run having a series of discreet constant speed values, the duration of each speed run being dictated by the number of cycles. The run is stopped when the end speed step has been reached and the defined number of cycles completed.

Update Run Details: This local calculation option refreshes the run values displayed, based on the selected run type and defined values.

The following values are used to specify the run characteristics.

Start Speed (rpm): Sets the start speed for the run in engine rpm.

End Speed (rpm): Defines the end speed for a ‘to speed’ run or the final step speed value in staircase runs. For other run types this values is ‘greyed-out’. As for start speed this the units are engine rpm.

Speed Change (rpm/s): Sets the rate of speed change in engine rpm per second for the ‘to’ run types. For the staircase run types this defines speed step size between each step in the staircase.

Time (s): For the ‘to time’ run, defines the run length in seconds. For the ‘staircase Speed x Time’ run this sets the time run at each step, again in seconds. For all other run types this is just a calculated parameter.

Cycles (s): For the ‘to cycles’ run, defines the run length in cycles. (a cycle is defined as 360 cam degrees). For the ‘staircase Speed x Cycles’ run this sets the number of cycles run at each step. For all other run types this is just a calculated parameter.

The dynamic calculations use a number of constants and tolerances to control stability and convergence. Three of these can be manipulated by the user to refine stability and convergence.

Accel Tol (m/s2): Defines the solution convergence tolerance. The solver checks the change in acceleration of each mass element between successive relaxation loops against this tolerance to confirm a converged solution.

Start Time Step (s): Sets the initial calculation time step size in seconds. The solver can reduce the size of the time step but it will never use a step size greater than this value.

Min. Time Step (s): Sets the smallest time step that the solver will reduce to whilst attempting to achieve convergence. If this value is set to the same value as the ‘start time step’ then no time step refinement is used by the solver.

CPS Operation Type

When the model types uses the CPS tappet, additional buttons are visible to control the operation of the simulation model. When acting as a cam profile switching (CPS) tappet, these buttons control if the tappet operates in low lift or high lift mode. When acting as a cylinder deactivation device (CDA), the buttons provide control of cylinder activation.

Solver Running

Also displayed on the ‘run’ data panel are the solver submit icon and the run stop icon. These icon actions are replicated by the pull down menu items, DynSpring / Run / Initialize and Start Dynamic Spring Run and DynSpring / Run / Stop/Pause Dynamic Spring Calculation.

Note that an interactive job can be paused and continued by using the ‘animation’ style icons in the main toolbar. These also include a ‘play’ and ‘fast forward’ icon. The ‘play’ icon allows you to continue a paused calculation from the current position without having to restart the calculation from time zero.

+$#>Data Field Descriptions. – Dynamic Spring Section - Display:

The ‘Display’ section controls the graphs, values and display properties of the graphical region. Setting the style of the graphs, the scale of the graphs and the drawn parameters. Additional features such as visibility of the 2nd local zoom window are also controlled through this panel.

Display, Values: Sets the visibility of the numerical display of the calculated parameters.

Display, Time History: Sets the visibility of the time history graphs. These show a prescribed section of the current solution runs results.

Display, Filled Tappet Pressures: Sets the visibility of the filling of the hydraulic tappet model. When one a solid fill colour is applied to the high and low pressure regions of the tappet representing the current internal pressures. The colour contour that the selected fill colour is based on can be edited through the coloured icon button adjacent to the display switch.

Display, 2nd Zoom Window: Switches the visibility of the zoom window. This additional display window allows the user to define an alternative local view such that different parts of the model can be viewed at the same time. The view in this window is controlled in the same way as for the main window using the dynamic zoom and dynamic translate options, but selecting inside the local zoom window. To change the size and position of the zoom window change to the edit mode and select adjacent to the lower left corner to change its position and adjacent to the upper right corner to change the size.

Filled Gas Spring Pressure: Similar to the tappet pressure fill above this option applies to gas spring models where the pressure in the gas spring regions can be filled in a colour. Again the colour is controlled by a contouring routine the settings of which can be edited by the user through the adjacent contour icon.

Time History graphs are plotted for the mass elements, link elements, tappet element and gas spring element. Only one from the mass and link elements can be displayed at a time. A separate switch defining which is displayed. For each of the four plot types given above a number of different results variables can be plotted. Each type has its own selection box to specify which should be displayed. The calculation can be paused at anytime and the displayed results changed, scaled etc.

The time-history plots can be used to produce numerical listings, printable and exportable graphs. To access these options click on the required graph with the right mouse button. Relevant options include;
                                   Open line(s) in Text Viewer
                                   Open line(s) in Graph Viewer (vs time)
                                   Open line(s) in Graph Viewer (vs angle)

The ‘scope line store’ facility can also be used within the dynamic analysis model. See Graph / Scope menu items.

Mass Display Results: Sets the displayed variable for the mass elements time-history graphs. Options available are;
                        Displacement (mm)
                        Velocity (mm/s)
                        Acceleration (mm/s2)

Link Display Results: Sets the displayed variable for the link elements time-history graphs. Options available are;
                        Compression (mm)
                        Force (N)

Tappet Display Result: Sets the displayed variable for the hydraulic tappet element’s time-history graph. Options available are;
HPC Pressure (N/mm2)
                        Check Lift (mm)
                        Check Flow (mm3/s)
                        Leakage Flow (mm3/s)
                        Supply Pressure (N/mm2)
                        Oil Bulk Module (N/mm2)
                        Check Valve Area (mm2)

Gas Spring Result: Sets the displayed variable for the gas spring element’s time-history graph. Options available are;
                        Supply Pressure (N/mm2)
                        Internal Volume (mm3)'
                        Internal Pressure (N/mm2)
                        Force (N)
                        Int. Temperature (C)
                        Leakage Flow (mm3/s)
                        Orifice Flow (mm3/s)'
                        By-Pass Flow (mm3/s)
                        By-Pass Lift (mm)
                        By-Pass Area (mm2)
                        Internal Mass (gms)
                        Internal Density (kg/m3)'
                        Leakage Flow (gms/s)
                        Orifice Flow (gms/s)'
                        By-Pass Flow (gms/s)'
                        Leakage Flow (m/s)'
                        Orifice Flow (m/s)'
                        By-Pass Flow (m/s)'
                        Leakage Flow (Mach No.)'
                        Orifice Flow (Mach No.)
                        By-Pass Flow (Mach No.)'

History Source: Sets either the specified mass or specified link elements graphs to be displayed, since only one can be visible at a time. Select either Mass Result or Link Result.

The time-history graphs are drawn with a scalar. This scalar can be changed to best view a particular variable in the screen space available. Separate scalars are provided for each time-history type, (i.e. mass, link tappet and gas spring).

Scale Values, Mass: Sets the scalar for the Mass elements time-history display.

Scale Values, Link: Sets the scalar for the Link elements time-history display.

Scale Values, Tappet: Sets the scalar for the Tappet element’s time-history display.

Scale Values, Gas Spring: Sets the scalar for the Gas Spring element’s time-history display.

Time History x-length: This variable controls the graphical length used for the x-axis of the time-history graphs.

Display Update Every: This setting controls the calculation step frequency at which the time-history graphs are updated. A smaller number we update more frequently but at the cost of a slower run time. The frequency of graphical refresh is also affected by the solver being run in ‘fast-forward’ mode. The default setting for this is 100.

Display Style: Controls the style of the time-history plots. The user can select from either the ‘rolling strip’ mode or the ‘cycle overlay’. The former displays the last buffered ‘n’ values rolling the graph to the left (or right) as each new point is added to the graph. The second display type only displays one cycles worth against a fixed x-axis angle position, such that each new point is added at the relevant x position and the display appears to update by wiping along the axis.

+$#>Data Field Descriptions. – Dynamic Spring Section - Results:

The results section provides the route for producing summary plots of the peaks (and troughs) of specific parameters such as valve seat force against cycle, speed or time. 

The time-history plots can be used to produce numerical listings, printable and exportable graphs. To access these options click on the required graph with the right mouse button. Relevant options include;
                                   Open line(s) in Text Viewer
                                   Open line(s) in Graph Viewer (vs time)
                                   Open line(s) in Graph Viewer (vs angle)

The ‘scope line store’ facility can also be used within the dynamic analysis model. See Graph / Scope menu items.

To display the summary graph select the required x and y axis variables.

X-Axis: Select the required x-axis from;
                            Cycle Number
                            Time (s)
                            Speed (rpm)

Y-Axis: Select the required y-axis from;
                            Max Seating Force (N)
                            Max Seating Force (N)
                            Max Valve Stem Force (N)
                            Max Cam Contact Force (N)
                            Min Cam Contact Force (N)
                            Valve Seating Angle (deg)
                            Max Valve Bounce (mm)
                            Max Tip Contact Force (N)
                            Min Tip Contact Force (N)
                            Min Valve Spring1 Force (N)
                            Max Valve Spring1 Force (N)
                            Min Valve Spring2 Force (N)
                            Max Valve Spring2 Force (N)
                            Spring1 Min/Max Force (N)
                            Spring2 Min/Max Force (N)
                            Max Valve Lift (mm)
                            Max HPC Tappet Pressure (N/mm2)
                            Min Valve Spring3 Force (N)
                            Max Valve Spring3 Force (N)
                            Spring3 Min/Max Force (N)
                            Max Gas Spring Pressure (N/mm2)
                            Max Gas Spring Temperature (C)
                            Max Gas Spring Force (N)
                            Spring Work(W)
                            Mass Consumption (gms)
                            Volume Consumption (mm3)

The spring work term refers to the gas spring element and not the conventional wire springs. Similarly volume consumption is the volume of gas consumed by the gas spring element.

To display a listing (and graph) of  the selected variables select the large ‘edit’ icon this will open the normal data listing edit window, from which you can display a graph of the listed numbers.

To assist in identifying certain summary results values additional data values are listed below the edit icon. These provide tolerances that are used to identify the seating point. They also define which spring link is to be used to recover the results for since not all buffered into the summary results only the selected link for each of the three possible springs, (inner, outer and CPS lost motion).

Tol. for min lift force (mm): Defines the value used to identify when minimum contact force occurs between cam and tappet. For calculation steps having an input lift less than this limit the minimum force check is not made.

Tol for seating angle (mm): Defines the value used to identify when valve seating needs to be checked for. For calculation steps having an input lift greater than this the valve seating check is not made.

Cycle No for Stair x time: Defines which cycle number at each step to store the results for in a staircase test. If this is set to zero all cycles are stored.

[Spring 1] Link recovery No.: Defines the element link number to use for recover and storage of summary link results for the first spring, (the first spring is drawn on the left hand side of the model).

[Spring 2] Link recovery No.: Defines the element link number to use for recover and storage of summary link results for the second spring, (the second spring is drawn on the right hand side of the model).

[Spring 3] Link recovery No.: Defines the element link number to use for recover and storage of summary link results for the third spring, (the third spring is the lost motion spring used within the CPS tappet model).

+$#>Results Description – Summary Report
 
This section describes the results variables listed in the summary report spreadsheets that are available for display on each section by selecting the ‘Report’ button. The summary report just lists the minimum or maximum value, (as appropriate). The complete curve for a particular result can be listed either through the ‘text results’ menu items, or via the ‘list’ option on the graphs right mouse menu. Where relevant a value is given for both the cam and the valve ends of the system.

The report lists a summary of the following results;

Minimum X, (deg): Lists the minimum cam angle for the profile, that is the angle for the first value in the lift table, (note this will be for zero lift).

Maximum X, (deg): Lists the maximum cam angle for the profile, that is the angle for the last value in the lift table, (note this will again be for zero lift).

Maximum Y, (mm): Lists the maximum displacement for the cam and the valve. For direct acting systems these would normally be the same value.

Minimum dy/dx, (mm/deg): Lists the minimum velocity for the cam and the valve. For direct acting systems these would normally be the same value. The limitations on this value would normally be due to tappet diameter restrictions.

Maximum dy/dx, (mm/deg); Lists the maximum velocity for the cam and the valve. For direct acting systems these would normally be the same value. The limitations on this value would normally be due to tappet diameter restrictions.

Minimum d2y/dx2, (mm/deg2): Lists the minimum acceleration for the cam and valve. For direct acting systems these would normally be the same value.

Maximum d2y/dx2, (mm/deg2): Lists the maximum acceleration for the cam and valve. For direct acting systems these would normally be the same value. Typical limits on the positive peak acceleration are 0.025 to 0.03 mm/deg2, but they are highly dependent on the system stiffness, tappet types (mechanical/hydraulic) and peak operating speeds.

Minimum d3y/dx3, (mm/deg3): Lists the minimum jerk for the cam and valve. For direct acting systems these would normally be the same value. Typical limits on minimum jerk are -0.003 to -0.01, but again these are highly dependent on the system the operating speeds and the required life.

Maximum d3y/dx3, (mm/deg3): Lists the maximum jerk for the cam and valve. For direct acting systems these would normally be the same value. Typical limits on maximum jerk are 0.003 to 0.01, but again these are highly dependent on the system the operating speeds and the required life.

Time Area, (mm.deg): Lists the total area under the lift curve, (including the ramps). The angle term is based on cam degrees.

Minimum +ve Radius, (mm): Lists the minimum positive radius of curvature for the camshaft profile surface. Allowable minimum values tend to vary since the radius itself should not be the limiting factor but the associated Hertzian contact stress and oil film thickness. A typical minimum, (bearing in mind the proceeding) is 2.5mm.

Maximum +ve Radius, (mm): List the maximum positive radius of curvature. This can be important for manufacturing, since large positive radii values can restrict the flow of removed material during the grinding operation. Thus the maximum allowable value is dependent on the manufacturing speed and processes.

Minimum –ve Radius, (mm): Lists the smallest concave radius calculated for the cam surface. If the cam profile is not concave, this item is listed as ‘convex’.

Maximum Eccentricity, (mm): Lists the maximum absolute eccentricity for the camshaft profile. This has different interpretations depending on the template type. The simplest concept is that of the direct acting system where it is the distance across the surface of the tappet that the point of contact moves from the centre line.

Maximum Stress, (N/mm2): Lists the maximum calculated Hertzian contact stress between the cam and the tappet surface. Contact stress is calculated at both zero speed and the ‘design speed’. The maximum value is normally calculated found for the zero speed case. The allowable values vary with a number of parameters and in particular with the material combination employed and the type of contact, (i.e. sliding or rolling). The cam angle that this occurs at is given in the second column.

Float Speed, (rpm): Lists the predicted cam float speed. The float speed calculation uses the defined spring loads, the specified effective mass and the profile accelerations to establish the point in the lift curve for which the minimum spring cover point exists. Each valve train template has its own assumed spring cover requirement that the static spring load must cover the static acceleration load by to cater for the dynamic effects of that particular valve train type. The user can modify the default settings of each valve train type. The cam angle for the minimum cover point is given in the second column.

Zero Speed Torque, (N.mm): Lists the peak cam lobe drive torque, (sometimes referred to as ‘stab torque’), for the zero spped condition, (i.e. no inertia load effects). For direct acting systems it also includes a friction component that is based on normal load multiplied by the sliding friction factor.

Design Speed Torque, (N.mm): Lists the peak cam lobe drive torque, (sometimes referred to as ‘stab torque’), for the ‘design speed’ condition, (i.e. includes the effect of both spring loads and inertia). For direct acting systems it also includes a friction component that is based on normal load multiplied by the sliding friction factor.

Zero Speed Force, (N): Lists the peak zero speed force for both the cam and valve ends of the system. This will be due to spring load only. (For direct acting systems the cam and valve end values will be the same).

Design Speed Force, (N): Lists the peak force for both the cam and valve ends of the system at the ‘design speed’. The design speed peak force is based on the summation of the spring and inertia loads. (For direct acting systems the cam and valve end values will be the same).

Nose Film, (um): Lists the oil film thickness at the camshaft nose, (i.e. 0 degrees position). The value at the nose is given rather than the minimum value since the oil film algorithm will normally give a zero minimum film thickness at the position of zero entrainment velocity, and hence the minimum would always be zero.

Specific Nose Film: Lists the specific oil film thickness at the camshaft nose, (i.e. 0 degrees position). The specific oil film non-dimensionalises the actual film thickness by dividing it by the relevant local surface radii.

Minimum Valve Clearance, (mm): Lists the minimum valve to piston clearance value. The calculation considers the relative phased motion of the valve and piston to identify the position of the minimum clearance. Typical target values for when considering nominal dimensions is about 10% of the maximum valve lift, although specific applications may require either closer tolerances, (such as for racing applications) or indeed larger clearances if broken belt clearance is desired.

Overlap Duration, (deg): Lists the overlap length in crankshaft degrees between the start of opening of the inlet valve and the closing of the exhaust valve.

Overlap Area, (mm.deg): Lists the area under the overlap region of the lift curve in terms of lift x crankshaft angle.

Max Tip Offset, (mm): Lists the maximum offset of the contact point on the valve from the valve centre line through the cycle.

Max Tip Stress, (N/mm2): Lists the maximum ‘hertzian’ contact stress on the valve tip. This will be the maximum of both the zero speed and design speed cases. The cam angle that the maximum valve tip stress occurs at is given in the second column.

Nose Lube No. (-): Defines the Lube number at the maximum lift point. The target for this is not rigorous with as much relevance being given to the slope of this curve as it crosses the zero line as to any single number at the nose point. Calculation based on a reduced oil film calculation that just involves geometry and not oil properties. Favored by component suppliers such as INA.

% Trapezoidal, (%): Lists the area under the valve lift curve as a percentage of the Trapezoidal area defined by the duration and maximum lift.

+$#>Results Description – Spring Design Results

The spring design section displays a number of additional results on the spring graphic that are not covered in the results report summary. These items are listed here;

Spring Length, (mm): Identifies the spring length for the condition described. The design conditions listed are for; the spring free condition; the as installed valve closed condition; an intermediate lift point specified by the user; the maximum lift position; the maximum solid position and a calculated solid position. The difference between the last two conditions is that the maximum solid length is based on the physical number of coils, (albeit with empirical corrections), whilst the calculated solid length is a calculated theoretical position at which peak wire stresses are calculated.

Load, (N): Identifies the spring load for each of the conditions. (a complete list of spring load variation is also available through the Text Results \ Display Spring Results menu option).

Rate, (N/mm): Identifies the spring rate for each of the conditions. (a complete list of spring rate variation is also available through the Text Results \ Display Spring Results menu option). Obviously for a linear spring, the rate value does not change with position.

Stress, (N/mm2): Identifies the spring wire stress for each of the conditions. (a complete list of spring wire stress variation is also available through the Text Results \ Display Spring Results menu option).

Number of Coils: Identifies the no of active coils for each of the conditions. (a complete list of the variation of the number of active coils with lift is also available through the Text Results \ Display Spring Results menu option). The total number of coils is assumed to be two more than the number of active coils at the free condition, (i.e. one inactive coil at each end) The design also assumes that from the free to the fitted point no change in the number of active coils occurs, thus this portion is taken as linear.

Frequency, (Hz): Identifies the spring natural frequency for each of the conditions. (a complete list of spring frequency variation with lift is also available through the Text Results \ Display Spring Results menu option). A linear rate spring will have a constant natural frequency, (i.e. does not vary with lift). A progressive rate spring is normally used to obtain a variation in the springs natural frequency for improved spring dynamics.

+$#>Theory – Polynomial Equations

Segment Polynomial Method.

The lift curve for each segment is described by a polynomial of the form:
{bmc bm0.wmf}
As many terms as necessary to meet the defined boundary conditions are used for each segment. The actual polynomial exponents used are taken from the supplied list, and the calculated coefficients can be viewed via the ‘solve / List Profile’ Segments menu item.

+$#>Theory – Contact Stress

Contact stress calculations are based on four basic types.
1) Flat Tappet on cam.
2) Spherical Tappet on cam.
3) Flat Cylinder on cam.
4) Barreled Cylinder on cam.

For case 1, 
{bmc bm1.wmf}
where;
	K = material constant
	p = load /unit contact width
	Rc = cam radius of curvature

For case 2, 
{bmc bm2.wmf}
where;
	P = total applied load
	Rc = cam radius of curvature
	Rt = tappet spherical radius
	K = Material constant
	c = geometric constant

For case 3,
{bmc bm3.wmf}
where;
	p =load/unit contact width
	Rf = follower (or roller) radius
	Rc = cam radius of curvature
	K = material constant

For case 4.
{bmc bm4.wmf}
where;
	P = total applied load
	Rc = cam radius of curvature
	Rf = roller radius
	Rr = roller crown radius
	Rt = tappet spherical radius
	K = Material constant
	c = geometric constant

+$#>Theory – Oil Film Thickness

Oil film thickness calculations are based on the formulation proposed by Dowson and Higginson.

The calculation is based on four cam / tappet geometric conditions;
1) Flat Tappet on cam.
2) Spherical Tappet on cam.
3) Flat Cylinder on cam.
4) Barreled Cylinder on cam.

For case 1 and 3,
{bmc bm5.wmf}
and 
{bmc bm6.wmf}

For case 2 and 4,
{bmc bm7.wmf}
and 
{bmc bm8.wmf}

where;
	W = dimensionless load factor
	G = dimensionless material parameter
	U = dimensionless speed parameter
	{bmc bm9.wmf} = minimum film thickness
	R = effective radius at contact
	k = ellipticity parameter

+$#>Theory – Drive Torques

Cam drive torque’s are calculated at each cam angle using the normal force, eccentricity, follower lift and coefficient of sliding friction. The normal force is the resultant of the spring and inertia loads and thus the drive torque’s are calculated for the Static condition, (no inertia load) and at the ‘design speed’.

{bmc bm10.wmf}
Where, {bmc bm11.wmf} is the coefficient of sliding friction.

For rolling contact rather than sliding contact the coefficient of friction should be set to zero.

+$#>Theory – Spring Design

The calculations used for the spring design use a number of fundamental equations:

{bmc bm12.wmf}

{bmc bm13.wmf}

{bmc bm14.wmf}

{bmc bm15.wmf}
Where, G = spring wire modulus of rigidity

{bmc bm16.wmf}
Where {bmc bm17.wmf} is wire density.

+$#>Theory – Overlap Area

The overlap area is defined as being from the start of valve lift through to the end of exhaust valve closing. The effect of valve clearance on these points is included. For the conventional lift based area calculation, the overlap lift values switch from using the inlet value to the exhaust value when the lift lines cross over.

For the effective area based calculation, the overlap area term is based on the current port discharge coefficient value, Cf;

{bmc bm18.wmf}

This is calculated for both the inlet and the exhaust valves and summed as for parallel resistances. i.e.;

{bmc bm19.wmf}

+$#>Theory – Bezier Acceleration Curves

The Bezier curve routines offer a very different kind of curve control where the data supplied represents control points rather than points on the curve itself. This can be illustrated by looking at a simple Bezier curve of degree four (cubic). As can be seen in the figure below, for each of the three Bezier curves, the points 2 & 3 deviate from the line between the end points 1 and 4. Looking at the vectors between these points, the greater the magnitude, the bigger the deviation whilst their direction determines the tangent of the curve at the end points. Therefore, in the three cases below, as all the vectors between the end points and their adjacent control points are the same, the tangents at points A1, B1 and C1 are the same as are the tangents at the points A4, B4 and C4. This feature of Bezier curves is important when considering the joining of two such curves (see below).

{bmc bm20.bmp}

Supplying a set of 6 control points (displayed as asterisks) the following curve will be drawn. Note that the curve always starts at the first control point and ends at the last control point, but in all probability will not pass through any other supplied control point.

{bmc bm21.bmp}

There is no direct control over end conditions with Bezier curves, but the fact that the position of the control point adjacent to the first (or last) data point determines the tangent of the curve at that point (see above), curves can be smoothly joined by taking account of this feature.

Therefore to join two Bezier curves, the joining point must obviously be at the same co-ordinate position, and the distance and angle between the adjacent control points must also be the same, such that these two control points lie in a straight line. Thus in the figure below, points A4 and B1 must be the same and points A3 and B2 must form a line that intersects A4 and B1. This will give a seamless join and forms a piecewise Bezier curve.

{bmc bm22.bmp}

The basic properties of Bezier curves described above are used to create a complete acceleration curve using six separate Bezier curves, each with a minimum of four points, connected together such that end points adhere to the rules given above to retain continuity of position and slope across the joins. The conventional ramps are added to the first and last points to create a complete cam profile. The curves for Velocity and Lift are calculated via differentiation and Jerk from integration of the complete Bezier curve, this dense but unevenly spaced data then being interpolated back onto the required even cam angle increment. Within the application a number of constraint s are applied to ensure that the basic shape of the Piecewise curve follows that required  for a cam profile, (i.e. number of zero crossings etc).

Because it is possible to drag one curves points independent of the others, (except for enforced continuity), the overall curve will not normally match the fundamental requirements of zero velocity at maximum lift and matching the closing ramps height and velocity. Options are provided that modify the selected point (or points) position in the prescribed manner to match these requirements.

A symmetrical profile will only require that the velocity is matched to zero at the maximum lift point, (this effectively matching the +ve and –ve areas under the acceleration curves).

With asymmetric profiles it is probable that when the velocity is matched to zero at the maximum lift point, their will be a discrepancy at the top of the closing ramp in either (or both) lift or velocity. Thus matching an asymmetric profile requires a two stage process. First match the velocity to zero at maximum lift then match the lift and velocity at the top of the closing ramp. Two menu options are given to do this for you in a single click.

The second step of the matching exercise requires two points to vary, (must be different points but could on same curve segment), each point having its own definable degree(s) of freedom, that is moveable in x and y, x only, y only, length only or slope only.

+$#>Theory – Dynamic Analysis

The Dynamic analysis solver is based on a lumped mass representation of the valve train. A time-marching solver is used that uses residual acceleration as the solution convergence check. A time steps starts with a prediction of the acceleration for each mass based on the previous end of time steps applied force conditions. From the calculated mass accelerations velocities and displacements are derived. An iterative relaxation technique is then employed to refine mass accelerations to within the prescribed tolerance.

Standard Newtonian equations are used for acceleration predictions. Additional force terms are included where necessary to simulate gas loads on masses, non-linear linkages such as valve seats.

Specific link elements are identified as being unable to support tensile load, (i.e. cam to tappet link), the connection being broken if the link has calculated tensile forces.

The theory employed for the solution of the gas spring is based on the same compressible gas algorithms used in the Lotus Engine Simulation Product. For more information on this refer to the theory section of the help file for this product.

+$#>Theory – Gas Spring

The Dynamic analysis solver is based on a lumped mass representation of the valve train. A 
Current F1 racing engines and some GP1 motorcycle engines employ small chambers filled with a gas, usually nitrogen, which serve the same function as a mechanical spring in a conventional valve train. These ‘gas springs’ circumvent the problem of spring surge by eliminating the coil spring entirely. A schematic of such a system is shown in Figure 5. The gas spring itself is represented by a chamber, 1, which is fed by the system supply connections, 2. The chamber also experiences mass transfer through a calibrated orifice, 3, and via leakage of the gas to the ambient, 4, via a sealing ring. The volume of the chamber varies as the valve is moved. The system is shown as part of a ‘finger-follower’ actuation mechanism which are common in high performance engines due to the lower frictional penalty they impose and the greater freedom of valve lift range and profile shape they facilitate.

{bmc bm23.bmp}
Schematic of Gas spring Model

The gas spring is modelled in Lotus Concept Valve Train by considering the change in properties of the gas in the spring chamber due to its change in volume and the mass and heat transfers between the various connected reservoirs. An ideal gas is assumed, the composition of which is defined by specifying the mole fractions of each constituent from a choice of 13 species. The variations of the properties of the gas as a function of temperature are also included. For each species the enthalpy is given by

{bmc bm24.bmp}

where  is the Universal Gas Constant and the coefficients a1 to a5 are taken from Benson. The enthalpy of the mixture is then given by 

{bmc bm25.bmp}

where Nspec is the number of species in the gas mixture and xj is the mole fraction of specie j. 

The specific internal energy and mass of the gas in the spring chamber is integrated using a fourth-order Runge-Kutta scheme. The internal energy at time level n+1 is given by 

{bmc bm25.bmp}

{bmc bm26.bmp}

where

{bmc bm27.bmp}

The chamber mass is integrated in the same way. The rate of change of internal energy with time is obtained from the First Law of Thermodynamics for an unsteady, open system in the form

{bmc bm28.bmp}

where h0 is the specific stagnation enthalpy of the gas entering or leaving the chamber, and Q represents the heat transfer rate through the gas chamber walls. The mass flow rates ({bmc bm29.wmf}) are obtained by solving the equations of compressible flow through an orifice.

+$#>How to…. Design a cam profile

The principal targets for suitable cam designs are;

1) Maximize valve time area.
	2) Limit accelerations to acceptable value.
	3) Limit eccentricity to safe working limit of tappet.
	4) Limit peak jerk levels to acceptable value.
	5) Limit contact stress to target.
	6) Achieve target float speed
	7) Minimize peak stab torques
	8) Check for concavity / minimum radius of curvature acceptable
	9) Nose oil film thickness above target
`	10) Maximum +ve radius of curvature acceptable for manufacture.

Normally to start a cam design you will have a number of targets and constraints. Since these will be job specific no foolproof procedure can be given that satisfies all situations. The generic procedure given here will need to be manipulated to suit specific cases.

The most common start point is the generation of a new cam design for an existing engine, the new cam being required to support a change in the performance specification. In this instance the geometry is know, as is the target valve duration and lift. 

1) Given the above assumptions select the file / new option and select the appropriate template, required valve/cam definition option and the polynomial type. If the cam profile is likely to be eccentricity limited then the second polynomial definition type should be selected. Otherwise the first polynomial type should be selected.
2) Correct the data values for profile, mechanism and static’s to reflect the actual values.
3) Edit the limit settings to reflect the targets relevant to the job. This will enable the reports to be used as a visual check on the design requirements.
4) Assuming that the required profile specification of lift and duration has been entered then the initial analysis and a review of the summary should indicate if changes are required. This could be to achieve a design target, or if the cam profile can be changed to increase the time area and stay within the design targets.
5) Use the point edit, point joggle options to move specific points on the profile to either achieve targets or improve time areas.

+$#How to…. Design a valve spring

The principal targets for spring designs are;

1) Achieve required system float speed through adequate spring loads.
2) Package spring in available space.
3) Meet spring stress range and calculated solid stress levels for spring wire.
4) Achieve high enough natural frequency to avoid excessive spring surge.
5) Have a spring design that can be manufactured, implies minimum No. of coils.
6) Produce cam contact stress acceptable for material combination.

Some of these targets are directly opposite and as such the design is a compromise between these conflicting objectives.

The program pre-fills the spring design section with some default data, the user needs to review the data to identify not only what information is required, but what alternatives exist in terms of setting the spring design.

The following steps identify a procedure for designing a valve spring, unfortunately because each job will have its own unique set of requirements and limitations it is not possible to state that this procedure is ideal for all.

1) Assuming that a target camshaft profile has been designed, then the initial requirements in terms of maximum lift and spring maximum lift load have been set and can be entered into the relevant data boxes. Spring load may be forced to change during the design to accommodate a viable spring design or to reflect an actual spring mass greater than what was assumed in the target camshaft profile design. There may be a requirement to protect for greater lift than the target design and this should be considered.
2) Initially assume a linear spring design and set the ‘delta from linear’ value to zero. The intermediate lift value will not influence the design until a delta value is specified. The intermediate lift value would normally be set to half the maximum lift.
3) For the first iteration of the spring design, select to control the wire diameter by defining the stress at maximum lift. Check the box next to this option and select a stress value of around 900 N/mm2. This would be typical for a shot peened spring wire of either Chrome-Vanadium or Chrome-Silicon composition. This value is used to tune the calculated solid stress which should be less than 1050 N/mm2, again assuming the same material type.
4) Based on the packaging requirements the overall spring diameter must be set. This can either be controlled on the inner diameter, if for example a carry over retainer is to be used or his spring is to be the outer of a nested pair, or controlled on the outer diameter if the package is restrictive on between valve space. Check the required diameter box and enter the appropriate value.
5) Initially control the spring load range, (and hence fitted load and rate), by setting the stress range to be 500 N/mm2. This is the typical limit for the above spring materials. This value will be later used to tune the fitted load. Check the box next to stress range and enter the appropriate value.
6) To control spring surge and also to limit the calculated solid stress value, initially check the box for ‘clearance to max lift’ and enter 1.5mm. A value a 1.5 mm allows for dimensional tolerances that will typically reduce the clearance at max lift by a further 0.75 mm. Later the fitted length will be set directly to provide a ‘rounded up’ design value.
7) Check that the material properties under the ‘advanced’ button are relevant for proposed spring material.
8) Now run the spring design by selecting the solve button.
9) Review the calculated spring results displayed in the table at the bottom of the graphical display. First check that the stress for the calculated solid position, (far right column), is at or just below 1050 N/mm2. Adjust the stress at maximum lift until this condition is achieved. Lower the stress at the maximum lift value to bring the calculated solid stress down and raise to produce the opposite effect.
10) If the number of active coils is less than 2.5 this will require a change in the overall diameter to length ratio.
11) Once the calculated solid stress is set the achieved wire diameter needs to be reviewed to either round up the diameter to an available wire size, or rounded up to a wire size the proposed a supplier will produce. Significant saving in lead times can be had by designing to a ‘standard’ wire diameter. Normally within the automotive range of wire diameters every 0.1 – 0.2 of a millimeter could be available, but obviously the supplier should be consulted on available wire sizes. Thus set the check box next to ‘wire diameter’ and entered the rounded–up diameter. This will tend to lower the calculated solid stress, but this will rise later with the inclusion of the progressive rate.
12) To improve the dynamic behavior of a valve spring the progressive rate is used. Enter a delta value that gives something like 0.3 to 0.5 reduction in the number of active coils between the fitted and fully open conditions. This will typically be 3 to 5 N.
13) Round the fitted length to a sensible engineering value, by setting the check box next to fitted length and entering the required value.
14) Ideally the spring natural frequency should be greater than 10x the maximum excitation speed. If this is not achieved then it can only be increased by a change in the overall spring diameter, or an increase in the spring rate. The spring stress range will limit the spring rate that can be achieved.
15) Check that the fitted load either matches or exceeds that used in the original cam profile design and that the mass contribution due to the designed valve spring is in line with that used to determine the effective system mass value.
16) Re-run cam profile with revised spring design to check float speed, contact stress and other cam profile results meet target.

+$#>How to…. Export Cam Data

	Cam profile data can be exported a number of ways in a number of different formats and listing a range of information. The normal route would be to use the ‘File \ Export Profile’ pull down menu command. This opens a dialog box that allows the user to export the current profile information either as simple column ASCII text or in Adams Teimorbit format. Both formats write the profile data against cam angle, (cam angle from –180 to +180 cam degrees). The output value can be one from the offered list;
		Phi_lift_data (cam)	Cam lift against cam angle
		Phi_rad_data		Cam radius against cam angle
		Xyz_data		x,y,z coordinate of cam surface
		The user can select the dimensional units as either, inches, millimeters or meters and can control the number of decimal points used to display the values.

	A preview option exists to review the file contents and format prior to writing the file.

 	It must be remembered that these options are listing the cam surface in a number of different definition methods. For example the cam lift is the lift of a point follower it is not in the case of the direct acting system the lift of the flat follower. The simplest way to export direct acting valve lift data is to use the alternative options 1,2 or 3 below.

	An additional separate option is provided on data export of cam data to export cam cutter data for any specified radius, (within the limits of any profile concavity). This is covered in the section ‘How to Export Cam Cutter Data’.

Thus to export the cam data;

1) Check calculation is current by selecting the solve \ update menu item
2) Select File \ Export menu item.
3) Select the export format as either Adams Teimorbit or ASCII by picking the required icon.
4) Select export style from the listed options.
5) Set the required dimension units and number of decimal points.
6) Check the displayed base circle radius is correct.
7) Add any required comment into the comment text edit box, (note this is only used within the Teimorbit format).
8) Preview file format and contents by selecting the ‘Refresh Preview’ button. If you are happy with the data and format proceed to the next item else change settings and re-check.
9) Enter required filename to save file too, either by typing the file name into the test box or using the file browser icon.
10) To write file select the ‘Write File’ button.
11) Once written select the ‘close’ button to return to the Concept Valve Train main window.
In addition to the above data export route cam profile information can be exported in a number of other ways:

1) Using the ‘list line’ option from the right mouse button menu. The displayed data can then be saved to a file using the local ‘File \ Save Text to File’ menu item, or alternatively copied to the clipboard using the right mouse menu options ‘select all’ and then ‘copy’. This data can then be ‘pasted’ from the clipboard into the required application.
2) Using the ‘Text Results’ option from the main pull down menu bar, select from the listed options the required results spread sheet to display. The displayed data can be saved to a file using the local ‘File \ Save Text to File’ menu item, or alternatively copied to the clipboard through selecting the required area by dragging the mouse over the required area, then using the right mouse button menu item ‘copy’. The selected data can then be ‘pasted’ from the clipboard into the required application.
3) Finally using the ‘Text Results \ Write Text File’ which allows the user to save the major cam profile data to a file, simply select the required file name using the standard file browser.

For an example of exporting data to ADAMS/Engine the ‘Getting Started’ document includes a tutorial, (Tutorial 8 ‘Export of Data’), that takes you through the steps of exporting the property and sub system files and then importing them into ADAMS/Engine. Open Tutorial

+$#>How to… Control the Graph Display

Each Section in the Concept Valve Train program has one or more graphical displays. The displays vary from a number of specific x-y graphs to scale drawings of the component geometry. The graphical displays are not just used to display calculated results but also provide a visual means of checking the data input. Additionally they become a means to vary a particular data value in an interactive way, where the user picks the required point/dimension and either ‘edits’ it or ‘joggles’ its position.

Sections that have more than one graphical display can be manipulated to display either all the available graphs or just one single graph. The collections of icons at the top left of the graph blocks indicate which one is currently displayed and allows the selection of ‘all’ graphs or another single one.

The user can change the minimum and maximum values of the graphical displays to best display the area of interest. Each graphical display has an autoscale function that will re-scale the x and y setting to ensure that all the plot is within the viewable space. The autoscale function can be performed either by selecting the pulldown menu item ‘graph \ autoscale’ or its shortcut keyboard equivalent of Ctrl +A, (i.e. selecting the ‘ctrl’ key and the ‘a’ key together). With either of these approaches if there is more than one graph displayed they will all be autoscaled. Graphs that are not visible will not be affected by this autoscale action. Individual graphs can be autoscaled by selecting the ‘autoscale’ option from the right mouse button menu.

The minimum and maximum values for the graphical displays can also be set directly by the user through the ‘graph \ edit axis settings’ pulldown menu item. Select from the list the required graph to set the axis limits for, then enter into the displayed list the required settings. Alternatively the axis setting for a particular graph can be clicking on the required graph and  selecting from the right mouse menu the ‘edit axis settings’ item. This will open the same displayed list box. Some graphical displays will retain the same scaling in the x and y axis directions, (i.e. mechanism layout), thus user supplied numbers will be adjusted to ensure the correct aspect ration is maintained.

If a particular area of the graphical display is required to be enlarged, the zoom function allows the user to select the region of interest. The zoom function can be performed either by selecting the pulldown menu item ‘graph \ zoom’ or by selecting ‘zoom’ from the right mouse menu. Once ‘zoom’ has been selected the cursor will change to a full screen cross hairs indicating that the zoom action is taking place. The user can cancel the ‘zoom’ event at any time by clicking the right mouse button. To zoom in on an area select one corner of the required region using the left mouse button then, either keep the mouse button held down and drag to the required rectangle then release or, release the button drag the rectangle to the required rectangle and press the left mouse button again. Even after the first point has been selected the user can still cancel the zoom event via the right mouse button. As with user defined axis scales, (see above), some graphical displays require the same scaling in the x and y axis directions, the zoom event takes this into account when setting the selected region.

+$#>How to… Print and Export the Graphical Displays.

The graphical displays can be printed, copied to the clipboard, or exported to a Windows metafile (.wmf). Each of the alternatives has specific occasions when they may be required. All of the print type options are accessed through the ‘graph’ pulldown menu.

The ‘copy to clipboard’ option takes the currently displayed graphs, (or graphical display), and copies it to the Windows clipboard. This copy is an exact image of what is currently displayed, including not only the axis settings but also background colour. This can the be ‘pasted’ into any required application that supports ‘cut and paste’ type events. The limitation of this approach is that the quality of the image is limited by the pixel resolution of the screen display, thus this will not produce high quality images. You can also of course copy the entire window to the clipboard not just the graphical part by using the ‘standard’ Windows copy function. That is with the required window ‘in focus’, (i.e. top title bar shows ‘blue’), select the ‘alt’ and ‘print screen’ keys together to copy the window to the clipboard. Then either use the ‘paste’ command within the target application, or the ‘shift’ and ‘insert’ key combination supported by most Windows applications to paste the image in. As for the copying of the graphics image alone this will not give a high quality image, since it to is limited by the screen pixel resolution, but it may well still be adequate for most needs.

The ‘print’ option will open the standard printer dialog box that will allow the user to select the required printer and any relevant formatting, copies etc. Print produced in this manner will not have the ‘grey’ background of the on screen displays, but will revert to the more normal white. Also the prints of graphs will be distorted to fill the available page size, thus the portrait/landscape setting will produce prints with different aspect ratio graphs. The graphical displays that require the x and y axes to have the same scale will retain the on-screen aspect ratio and simply expand to fill the available plot space.

The ‘export’ option will open the standard browser dialog box to enable the user to enter the required file name to save the graphical image too. Only Windows metafile format is currently supported. The saved image will be a high resolution image than can be imported into any package that supports graphical import of metafiles.

+$#>How to… Edit On-Graph Data

Each Section in the Concept Valve Train program has one or more graphical displays. The displays vary from a number of specific x-y graphs to scale drawings of the component geometry. The graphical displays are not just used to display calculated results but also provide a visual means of checking the data input. Additionally they become a means to vary a particular data value in an interactive way, where the user picks the required point/dimension and either ‘edits’ it or ‘joggles’ its position.

The ‘On-Graph’ data can be changed via the graphical displays in either the ‘edit’ mode or the ‘joggle’ mode. The user can switch between these modes by using the two icons displayed at the top of the graphical region on each section. (note that the static’s section does not have any ‘On-Graph’ data editing since all displayed curves are calculation results, hence the edit and joggle icons do not appear at the top of this sections graphical display). 

With the ‘edit’ mode when the user selects a particular point or dimension a dialog box is opened that display the current data value(s), such that the user can change it to the required number(s). 

The joggle mode allows the user to change the selected data value in steps, the steps being either ‘normal’ or ‘fine’. The joggle symbol is used to indicate which particular point or dimension is currently being ‘joggled’. The number of arrows displayed on the joggle symbol identify the number of directions that the value can be changed, (i.e. a pivot point can be moved in either -x, +x, -y or +y and will thus have four arrows on its joggle symbol, whilst a length dimension like the base circle radius will only have two arrows since it can only be made larger or smaller). To actually joggle the value use the combination of the ‘ctrl’ key with the up, down, left and right keys for ‘normal’ joggle step size or the ‘Shift’ key with the arrow keys for ‘fine’ joggle steps. The ‘fine’ joggle step size is a tenth of the ‘normal’ step size. The joggle size for each data type can be changed from the default values using the pull down menu ‘Solve \ Edit Joggle Sizes’.

‘On-Graph’ data values that can be edited or joggled are indicated either as ‘dots’ on the profile section's graphical display or as red arrows and red crosses on the other graphical displays. The visibility of these red arrows and crosses can be toggled on/off via the pull down menu item ‘graph \ view joggle points’. 

All edit and joggle activities will automatically update the current solution, either when selecting ‘ok’ for the edit mode or at each key press for the joggle mode.

Data points on the profile graphs that have been edited or joggled become shown in ‘white’ to indicate that a value has been given to that point in that particular derivative. Dots shown in ‘grey’ currently have no data value assigned to them and will not be used in constraining the profile curve. It is possible to remove a data assignment to a point on the profile graphs by using the ‘Unfix Point’ option from the right mouse menu. It should be noted that not all points can be ‘freed-up’ in this way since they may form part of the minimum definition requirement of the current polynomial type. See also ‘How to… Design a Cam Profile’.

+$#>How to…. Create and Use a DataBase

The DataBase options included into the Concept Valve Train program are intended to not only provide a means by which existing cam designs can be used as the start point for a new design, but with the ability to sort database entries based on both supplied data and calculated parameters, its becomes a means of identifying limiting design factors.

To set up a new database the user must first create the target folder. A number of Lotus Software products and tools use a common database approach, where each database is stored under a common file folder. The user then points the application to this common file folder, each application having its own predefined sub folder name. The sub folder name for the concept Valve Train is ‘CAMPI’. 

The steps to create a new database are;

1 Use Explorer to create the required folder, i.e. for example a folder name C:\lesoft\DataBases. Check that the properties of the created folder have the ‘archive’ property box checked. (hint, use right mouse button on folder and select ‘properties’ from the menu list).

2. Create a sub folder ‘CAMPI’ under this top level data base folder. Check that the properties of the created folder have the ‘archive’ property box checked. (hint, use right mouse button on folder and select ‘properties’ from the menu list).

3. Create a sub folder under the ‘CAMPI’ specific folder, one folder for each required separate project, (note that they could all go into one sub folder under the ‘CAMPI’ folder, but the use of different sub folders helps to identify project groups.). Check that the properties of the created folder have the ‘archive’ property box checked. (hint, use right mouse button on folder and select ‘properties’ from the menu list).

4. Save to this project sub folder the required Concept Valve Train data files, (these data files can either be existing ones copied through Explorer or new ones saved directly from the Concept Valve Train interface.

5. From the interface point the application at the top level database folder using the pull down menu item ‘DataBase \ DataBase Folder’. Enter into the data box the full path name of the top level folder, (in this example ‘C:\lesoft\DataBases’). Note it is not necessary to include the ‘CAMPI’ folder name as this is assumed.

6. The database can now be used to save data to or extract information from.

Using the DataBase;

To use the database it must first contain valid Concept Valve Train data files. These can either be copied over using Explorer or can be saved directly using the ‘File \ Save’ pull down menu option and using the browser to locate the database folders. The save_as browser can also be used to create new project sub-folders in the database. Once some data files are contained within the database folder structure, they can then be interrogated from within the interface and loaded into the application as required.

The first time that you access the database using the ‘DataBase \ List Entries’ pull down menu item, the database manger will build a scratch file that contains the necessary information for the application to efficiently use the data. On future opening of the database, the application will check for the existence of this scratch file before it proceeds, this leads to subsequent rapid access to the data. If the information in the database has been changed, i.e. a new file has been added or an existing entry modified, then the database scratch file will need to be re-created. This is done by using the pull down menu item ‘DataBase \ Rebuild DataBase Scratch File’.

To view the entries in the database use the pull down menu item ‘DataBase \ List Entries’, this will open the DataBase spread sheet listing one horizontal line for each entry in the database. If the spread sheet fails to open check that the folder pathname is correctly specified and that the folder/file properties have their archived property box checked.

For each entry in the database the following values are listed;
	Folder:			Lists the sub-folder name that the entry is stored in.
	Type			Identifies the valve train template type
	Duration (deg)		The top of ramp timing in cam degrees
	Max Cam lift (mm)	The maximum cam lift
	Max Valve lift (mm)	The maximum valve lift
	Min Cam Velocity (mm/deg)	The minimum cam velocity
	Min Valve Velocity (mm/deg)	The minimum valve velocity
	Max Cam Velocity (mm/deg)	The maximum cam velocity
	Max Valve Velocity (mm/deg)	The maximum valve velocity
	Min Cam Acceleration (mm/deg2)	The minimum cam acceleration
	Min Valve Acceleration (mm/deg2)	The minimum valve acceleration
	Max Cam Acceleration (mm/deg2)	The maximum cam acceleration
	Max Valve Acceleration (mm/deg2)	The maximum valve acceleration
	Min Cam Jerk (mm/deg3)	The minimum cam jerk
	Min Valve Jerk (mm/deg3)	The minimum valve jerk
	Max Cam Jerk (mm/deg3)	The maximum cam jerk
	Max Valve Jerk (mm/deg3)	The maximum valve jerk
	Cam Time area (mm.deg)	The total cam lift time area, including ramps.
	Valve Time Area (mm.deg)	The total valve lift time area, including ramps.
	Min convex radius, (mm)	The minimum convex cam surface radius.
	Max convex radius, (mm)	The maximum convex cam surface radius.
	Min concave radius, (mm)	The smallest concave radius of the cam surface.
	Max Eccentricity (mm)		The maximum eccentricity across the tappet.
	Max stress (N/mm2)		The maximum Hertzian contact stress.
	Float Speed, (rpm)		The estimated valve float speed.
	Zero speed torque (N.mm)	The peak zero speed drive torque for the lobe.
	Design speed Torque (N.mm)	The peak design speed drive torque for the lobe..
	Nose Film (um)			The calculated oil film thickness at the nose point.
	Specific nose Film, (um)		The specific oil film thickness at the nose position.
	Valve Clearance, (mm)		The minimum valve to piston clearance dimension.

A number of actions can be performed on the database spread sheet by the use of the right mouse button menu options. The actions available depend on the current spreadsheet selection, to select an entry, (horizontal line in the spreadsheet), click in the far left-hand box containing the entry number. To select a column click on the box containing the text header of the required column. 

To load an entry from the database into the program highlight the required entry as outlined above then select ‘Load Entry as Data File’ from the right mouse menu. If the menu item is ‘greyed’ out this is because either more than entry is currently selected in the spread sheet or an incomplete selection has been made. Loading an entry in this way will close the spreadsheet and return to the main interface having loaded the data file for the selected entry.

A number of sorting functions can be performed on the data base list. A particular column can be sorted in order of highest first or lowest first. This is done by selecting the required column to sort, then select either ‘Shuffle selected column by highest’ or ‘Shuffle selected column by lowest’ from the right mouse menu. If these options are not available then a single column has not been selected. Any sorting can be undone by selecting the ‘Revert to Original Order’ item from the right mouse menu.

The number of entries actually shown can be controlled using a mix of ‘hide’ and ‘show’ commands together with high clip, low clip and pass filters. To’ hide’ an entry, select the entry required the select ‘Hide Selected Entry(s)’ from the right mouse menu. Multiple sequential entries can be ‘hidden’ in a similar way.

To hide entries based on a particular column’s value, select the column of interest then use the right mouse button menu items, ‘High Clip Selected Column’, ‘Low Clip Selected Column’ or ‘Pass Clip Selected Column’ as appropriate. If these menu items are ‘greyed’ out then the column selection is either incomplete or inappropriate. These clipping actions should not be performed on columns that are text entries, such as folder names. The high clip option prompts the user for the high clip value, entries that have a value in the selected column greater than that entered will be hidden. The low clip option prompts the user for the low clip value, entries that have a value in the selected column less than that entered will be hidden. The pass clip option ask for both high clip and low clip values, entries that have a value in the selected column greater than the high clip limit or lower than the low clip limit will be hidden.

To revert back to showing all entries, (i.e. make hidden entries visible), select ‘Show All Entries’ from the right mouse menu. Alternatively to switch between hidden and visible, (i.e. hide visible and show hidden), select ‘Swap Show/Hide Entries’ from the right mouse menu.

To close the database spreadsheet without loading a file and return to the main interface, simply close the spreadsheet using the ‘x’ in the top right corner or the ‘close’ option from the window menu at the top left corner.

+$#>KHow to…. Clip and replace a point via interpolation

When the profile data is defined by a list of points, (rather than through the polynomials). Individual points can be replaced by an interpolated value, the interpolation being based on the current segment size and smoothing value. To change to this ‘replace mode’ select the clip icon from the top of the profile graphics. Then when picking the point you require to ‘clip and replace’ a simple message box will identify the point picked by its angle, its current y value and the calculated interpolated value. Selecting okay will replace the current y value with the interpolated one. Selecting cancel will ignore the ‘clip and replace’ event.

+$#>How to…. Export an ADAMS/Engine Sub-System model

To export a Sub-System model from Lotus concept valvetrain so that it can be imported into ADAM/Engine to perform a full valve train dynamic analysis, open the ‘Export’ dialogue box using the ‘File \ Export Profile’ pull down menu command.

{bmc bm30.bmp}

Check that the ‘Valve Train Sub-system’ icon is selected in the ‘Select export type’ panel and that the ‘Adams Teimorbit’ icon is selected in the ‘Select export format’ panel and finally that the ‘Subsystem’ button is selected above the ‘file preview’ area.

Ensure that the profile filename is defined. If not use the ‘browse’ icon to locate the .pro file. If you type the filename in directly enter the full path name. If the browser does not open in the standard folder, (normally C:\private.cdb\cam_profile.tbl), you can use the setup menu option back in the main window to point to the required location.

Select the required tappet sub-model type. You will normally get at least three options, ‘Solid Tappet’, ‘Spring/damper Tappet’ and ‘Hydraulic tappet’. For the push rod valve train type a fourth option is provided for a hydraulic tappet with a floating bridge piece. As the tappet model type is changed so the template filename changes to point to the default for this model/mechanism type. The user can override the default setting by browsing for your own template file. The browser should by default point to a sub folder location of the installed folder, i.e. c:\installed folder\AdamsEngine\Templates.tbl, if this is not the case again the setup menu back in the main window can change the default folder path.

Enter the required sub-system file name, if this is entered directly in to the text box ensure the full path name is given. Alternatively use the ‘browse’ icon and this will add the full path and the extension onto any entered file name. If the browser does not open in the standard folder, (normally C:\private.cdb\subsystems.tbl), you can use the setup menu option back in the main window to point to the required location. Using the browser to enter the filename will result in the user being prompted whether to ‘Write File Now’, selecting ‘yes’ will result in not only the sub-system file being written but also the required individual property files. (If the file already exists the user will be warned of this potential loss of the existing file). Selecting ‘no’ will simply display the selected file name in the edit box.

If you choose not to write the file out when you first select the filename from the browser, you can write the files out by selecting the ‘write file’ button. If the ‘preview’ button is set to something other than ‘subsystem’, then only the individual property file for that selection is written out.

The file preview text box can be used to view individually the sub-system file or the individual property files. Selecting the ‘refresh preview’ button will update the preview display and display the current file selection with its associated values. The display can be scrolled and if required edited directly and saved using the ‘save preview’ button. Note that the ‘save preview’ option will only save a single file, even if ‘subsystem’ is selected.

The dynamic analysis model required for ADAMS/Engine require significantly more data than that needed for the kinematic analysis in Lotus Concept Valve Train. In some instances this additional data can be either calculated by Lotus concept valve train, (i.e. camshaft lobe mass properties), or use a user defined fixed value, whilst in others only a user defined value is appropriate, (i.e. contact properties).  The choice on whether to use calculated values or the user definable defaults can be made on an individual property file basis. If from the file preview buttons you select something other than ‘subsystem’ then an additional selection box is displayed titled ‘Mass Property Values’. This gives the user the choice of either ‘calculate’ or ‘Use Defaults’. The setting of these property file mass calculations is saved with your model file.

The default values for ‘default mass calculations’ and for the ‘default only’ is accessed through the notepad icon. on the export dialogue box. (They can also be accessed from the pull down menu option Setup \ Edit ADAMS/Engine Data Defaults on the main window. The scrollable spread sheet is split into individual component sections, i.e. cam_1, the notation for which is the same as is used within the Adams template and sub-model. The current component sections are;
	cam_1
	plate_1
	plate_2
	spring_1 (general)
	spring_1 (spring-damper)
	spring_1 (multi-mass)
	tappet_1 (general)
	tappet_1 (rigid)
	tappet_1 (mech spring damper)
	tappet_1 (hydraulic)
          	tappet_2 (rigid)
	valve_1
	rocker_1
	roller_1
	pushrod_1
	bridge
	cam_tappet_contact
	tappet_valve_contact
	cam_roller_contact
	rocker_tappet_contact
	rocker_valve_contact
	bridge_to_valve_contact
	roller_to_cam_contact
	valve_to_bridge_contact
	parameter

For each component/entity a number of relevant variables are presented, displayed for each is the current user value and for reference a ‘default’ value. Users can edit the ‘user values’ and these are used to populate the property files. These ADAMS/Engine user defaults can be saved as part of the Lotus concept valve train model file. This ‘save’ option is set via the pull down menu item Setup \ Include ADAMS/Engine Data Defaults in File in the main window.

{bmc bm31.bmp}

+$#>How to…. Export Cam Cutter Data

The cam profile data can be exported in the form of ‘cam cutter’ information, this is as a table of translating lift of a specified radius follower. To open the ‘export’ dialog box select the File \ Export Cam Cutter Data pull down menu command. The user should then specify the required cutter radius, the output lift units, the number of decimal points and check that the correct value is given for the base circle radius.

To define the destination of the export file, either enter the file name directly into the filename entry box, giving the full pathname, or use the file browser icon to locate/enter the required name. Using the browser to enter the filename will result in the user being prompted whether to ‘Write File Now’, selecting ‘yes’ will result in the file being written immediately. (If the file already exists the user will be warned of this potential loss of the existing file). Selecting ‘no’ will simply display the selected file name in the edit box.

If you choose not to write the file out when you first select the filename from the browser, you can write the files out by selecting the ‘write file’ button.

The file preview text box can be used to view the cam cutter file. Selecting the ‘refresh preview’ button will update the preview display and display the current export file contents. The display can be scrolled and if required edited directly and saved using the ‘save preview’ button.

The producing of the cam cutter from the calculated surface data relies on a curve fitting and integration process, this process is based on a Chebshev series where the user can control the size of the segments used and the smoothing value applied. To edit these values select the notepad icon. on the dialog box.

{bmc bm32.bmp}

+$#>How to…. Import Translating Cam Data

To evaluate existing cam profiles you can apply imported cam data to the cam side of the model. This cam data would normally only be available in the form of lift of a translating follower. Since this follower size may be different from that actually within the model and for valve train types 2 and 3 where the code actually uses circumferential lift and not translating lift, a conversion is required to get the correct applied motion.

To import translating data to the cam side of a mechanism, first fully define your required system, and ensure that the definition side is set to ‘cam motion’. Then to import the data use the pull down menu option File \ Import 1deg lift data or File \ Import Angle+Lift Definition. The two options work through the same process with the exception that the first assumes that the data is provided in 1 cam degree steps and that only lift data is provided, (angle data is added automatically). The second option requires both angle and lift be supplied, but they may be at an increment other than 1 deg. Both options require the files to be in column ASCCII format, with each value (or pair of values angle/lift), being on a separate line.

The standard file browser is displayed for the user to locate the required input file. Once this has been identified the user is prompted to define the type of data being provided.

{bmc bm33.bmp}

You need to identify whether the imported lift data is either a translating flat follower or a translating radiused follower. If the later then the follower radius is required. The other option is whether to correct the data such that the maximum lift occurs at 0 degrees.

For direct acting and pushrod systems the supplied translating data is then corrected for any radius difference between import and model and maximum lift shifted if requested. For the other valve train types of finger and rocker systems where the ‘cam lift’ used within the application is actually circumferential lift, a conversion is performed to turn the translating data firstly into rocker angular displacement and then circumferential lift. Through this conversion a number of angular corrections are performed to compensate for the effect that the rocker arm length changes have on actual angular contact positions. Again a maximum lift correction is performed is requested.

Profile data imported in this way will have different data variables presented for the ‘profile’ screen layout than seen with the normal profile design screen, (see below). The user can change the segment size and smoothing values used on the converted circumferential data, or edit individual data points directly. Individual ‘rouge’ points can be replaced using the clip and replace function

{bmc bm34.bmp}

An additional route for data import is to load data from the generic data spread sheet. This is accessed via the File \ Load from Spread Sheet. menu item and provides a generic import route for entering and sorting data prior to importing as defined cam motion. This method can be used to load a single column, or multiple columns. When importing multiple columns they should be in the normal order from angle, lift through the derivatives for as many as are to be imported.

Should an import fail and the problem be detected by the import process, the problematic file will be displayed in a text editor type display for the user to view/modify before either aborting the import or re-trying.

+$#>KHow to…. Animate Static and Dynamic Forces

Within the Mechanism section it is possible to display the forces and torques associated with either the static condition (zero rpm) or the dynamic condition (design speed). The forces are displayed as scaled arrows indicating both direction and magnitude, whilst the magnitude of the drive torque is indicated by both the arrow head size and the angle around the cam centre. The visibility of the forces/torques is set by the menu items View \ View Zero Speed Forces or View \ View Design Speed Forces. Note that it is only possible to display either the zero speed or the design speed cases individually, you can’t display both at the same time. Selecting Zero Speed with Design Speed already visible will switch Zero off and similarly with Design. To turn both off select the currently visible menu item. The display can be controlled via the settings dialogue box opened from the View \ Forces/Torques Display Settings.

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Forces and Torque’s Display Settings Dialogue Box

From the settings dialogue box you can individually turn on/off the forces, torque’s and associated values using the check boxes. The scaling of the arrow head sizes is controlled by the two scale factors. The ‘Auto-Set’ buttons provide a convenience tool that will provide scale values to suit the current display and results. The colour of the arrows can also be controlled using the ‘Colours’ selection box. Animating the mechanism with the Video Icons on the toolbar will animate the forces and torque’s, this showing the incremental positions.

+$#>How to…. Animate Static’s Results on Mechanism

In addition to viewing the static’s results graphically in the Statics section a selected static’s variable can be displayed in the Mechanism section drawn correctly orientated on the camshaft such that it rotates with the camshaft indicating angular position and magnitude. The visibility is controlled via the View \ Display Statics Results menu item and the settings are controlled via a dialogue box accessed via the View \ Statics Result Display Settings.

{bmc bm36.bmp}
Static’s Display Settings Dialogue Box

The displayed parameter is set via the top selection box. The list being a section of the same list presented for the Static’s section graphs. The parameter can be drawn on the lobe with one of three styles of origin. The zero point can be the cam centre, the cam surface or a user defined axis. The scaling is controlled by having the range being scaled to a function of the base circle radius, the default being 2x the base circle radius for the full-scale deflection. An additional setting is provided to control whether to plot the true sign or the absolute value of the selected property. The colour of the static’s result plot can also be controlled using the ‘Colours’ selection box. Animating the mechanism with the Video Icons on the toolbar will rotate the camshaft the selected parameter being drawn relative to the camshaft position. A local menu item View \ Display Static Result allows the user to change the visibility setting without needing to close the settings dialog box.

+$#>How to…. Control Static’s Results Graphical Display

From version 2.04 onwards the static’s graphs were no longer restricted to the previous pre-determined and fixed 6 plots, (the defaults are still the original fixed plots). The user can now choose not only what x and y parameters to plot, (with some restrictions on suitable matching), but also the form of the graph.

To change the displayed static’s result open the Static’s Plot Settings dialogue box either via the right mouse menu item Set Statics Graph Variables or from the main menu item Graph \ Set Statics Graph Variables. This will open the settings dialogue box for the chosen graph.

{bmc bm37.bmp}
Static’s Plot Settings Dialogue Box

The user can now choose the x and y parameters to display. Because the results from all the sections can be plotted some restrictions apply on the compatibility of the chosen x and y variables. For example selecting the y parameter to be the FFT Valve Acceleration Magnitude the application checks that the x parameter is one from the FFT section, i.e. Harmonic Order If this is not the case then the x parameter is changed to suit the selected y.

The settings dialogue box also provides control to the no of decimal points used on line listing.

The plot style can be changed to be either a line plot (previous default), Bar chart, filled bar chart or a Polar plot. For the polar plot the x-parameter is taken as the angle and the y-parameter is the magnitude.

The plot labels can also be edited through this dialogue box. The Auto Set Axis Labels option automatically setting the labels based on the chosen parameters. To retain your own labels uncheck this option.

+$#>KHow to…. Build a Dynamic Model

A dynamic model can be built from scratch by defining model type and then adding/editing the properties of individual mass and link elements. This can be a time consuming task and is more suited to refinement of an already created model.

The simplest method for creating a dynamic model is to make use of the internal functions that can created a fully populated dynamic model based on a combination of the current static’s model, the default Adams Engine export properties and some additional default values such as spring link damping.

To be able to use these auto-create convenience factors you must ensure that the data in both the kinematics static’s section and the spring design section is correct. Once you have confirmed that the data is correct and that where necessary the Adams Engine defaults are correct for your model, change to the Dynamics Module by selecting it from the top menubar selection box.

{bmc bm38.bmp}
Changing to Dynamics Module

If you are unable to change to the dynamics module check that you are licensed to run this separately licensed module. To view the complete list of Adams Engine default values use the menu item Setup / Edit ADAMS/Engine Data Defaults…

Once in the Dynamics module the main menubar item DynSpring is now enabled. Note that the model displayed is not yet based on your own data but rather displays the default mechanical tappet single spring dynamic model.

To create the model based on your defined kinematic model select from the main menubar DynSpring / Model / Create Full Dynamic Model from Current Static Design Data. From the menu options given, select the one required for your model. The options given are;

             Solid Tappet – Single Spring
             Solid Tappet – Double Spring
             Solid Tappet – Gas Spring
             Hydraulic Tappet – Single Spring
             Hydraulic Tappet – Double Spring
             Hydraulic Tappet – Gas Spring
             CPS Tappet – Single Spring
             CPS Tappet – Double Spring
             CPS Tappet – Gas Spring

You are prompted to confirm the data loss of the existing model before the new fully populated model is created and displayed. Individual element properties can now be examined either by selecting the required element from the list in the component selection box or by selecting the element on the graphical display with the mouse.

The current selected model element is drawn filled in red.

Further model creation menu items are available that only create/modify a single part of the model. Each of these sub sections is used collectively by the complete model creation routine.

If you require to just update one of the valve spring part of the dynamics model you can use the menu items DynSpring / Model / Create Dynamic Spring 1 From or DynSpring / Model / Create Dynamic Spring 2 From. Then use the User Specified Spring Props option to define the spring model from simple spring properties.

{bmc bm39.bmp}
Create Spring from User Properties

As an example of how the Adams Engine defaults are used to define the dynamics model, the DynSpring / Model / Update Retainer Mass Properties from Current Settings menu item will re-calculate the retainer mass. The calculated number is displayed in a dialogue box along with the parameters used from the Adams Engine and their current values. 

{bmc bm40.bmp}
Updating the Retainer Properties

It is possible to change from a mechanical model to hydraulic model without losing the remainder of the model data. The option DynSpring / Model / Hydraulic Tappet Properties from Adams/Engine Settings will just replace the existing solid tappet with a hydraulic model. Should you later modify the hydraulic properties in the dynamics module and require these to be used as the default Adams Engine values, (i.e. if you subsequently require to export to a full Adams Model file), you can copy them back to the defaults using the relevant menu.

A specific menu is provided that allows the removal of the second spring (if present) again without the recourse of creating a new model.

+$#>KHow to…. Run a Coupled Dynamic / Engine Simulation

The concept behind running a coupled dynamic valve models within the engine simulation was the subject of a recent Lotus Engineering paper ‘A coupled Dynamic Valve Spring and Engine Performance Simulation’ presented at GPC 2003. Described here is the process by which a user can set up the models to perform a coupled analysis.

To be able to run a coupled valve train dynamic and engine gas dynamics simulation you will need to be licensed on both products, (check with your LESOFT software vendor if not sure).

The normal route would be to have previously built and separately validated both the engine simulation model and the valve train dynamics model. What we know need to do is put them together.

Each valve component in the engine simulation model has its own unique dynamic valve model that can be edited independently. The reality is that you will probably only want a maximum of two different dynamic models, one for the inlet valves and one for the exhaust valves. This unique model for each valve must be remembered since you need to ensure you are aware of which dynamic valve model you are editing when. The title bar of the valve train module will indicate if you are currently editing the standard dynamics model or one associated with an engine simulation valve. For an engine simulation valve the string (Valve n) where ‘n’ is the valve number in the engine simulation model is appended to the valve train model file name.

If you enter the valvetrain dynamics module in the normal way from LES by using the Tools menu or icon you will not be editing one of the LES valves dynamic model only the ‘standard’ dynamics model. To edit a particular engine valves dynamic model you must first make the valve a ‘dynamic’ valve.

To create an engine simulation models valve dynamic, first load the required model. Select the valve of interest and then look at the bottom of the elements property sheet. The Model Option selection box allows you to choose between Static and Dynamic valve types.

{bmc bm41.bmp}
Changing to Dynamic Valve Type

Once changed to dynamic valve the valve symbol will change to indicate that it is dynamic and the Edit Properties menu option will be enabled.

{bmc bm42.bmp}
Dynamic Valve Symbol

Selecting the Dynamic Model Data option will take you into the dynamics section of the valve train module for the current valve element. This would be the route by which you would create dynamic valve models one at a time. If you choose this route to create the dynamic valve elements you can of course use the right mouse menu option Copy Data to… to copy the defined dynamic element to the other relevant inlet or exhaust valves.

Alternatively you can create the ‘standard’ dynamics model by entering the valve train module via the conventional Tools menu or icons. To apply the dynamics model to the required engine simulation valves you use the File / Make Current menu item. Identify the required valve, (or valves), ensure the Include Dynamic Model option is checked and select Apply.

{bmc bm43.bmp}
Make Dynamic Model Current Dialogue Box

This is all you need to do to enable a coupled dynamics analysis. The solver will detect the presence of the dynamic valves and initialise and enable the necessary solver sections.

Additional results are available in the prs results viewer that relate to the dynamic valve elements. These are selected in the same way as any other prs graph variable, (see .prs graph status). Additional results include Valve seat force, Valve tip force, valve stem force, cam contact force for all dynamic model types, with further results available for gas springs and hydraulic tappets.

+$#>How to…. Define a Variable Radius Follower

For rocker and follower systems it is possible to define the valve end radius to be something other than a constant radius. The follower can be defined as a radius that varies with angle. The angle is zeroed at the point of contact during the base circle. It is defined as –ve towards the pivot point. The zero angle can be offset by a separate angle.

One way of creating a non-uniform follower radius would be to design a cam profile for a direct acting system and export the profile in an r-theta format using the normal profile export facility.

To illustrate how you would use the variable radius feature, the following uses the ‘standard’ finger follower data as an example, (i.e. File / New and select ‘Finger Follower’, ‘Cam Motion’, ‘6 Segment Poly, 11 Points (default)’). In the ‘Mechanism’ section select the small icon next to the Valve end follower Radii.

{bmc bm44.bmp}
Selecting the Variable Radius – Mechanism Section

When this option is selected instead of the radius being displayed an edit button is shown. To define the radius data select the this edit button. Define the number of definition points and then enter the angle and radius information. Remember that the zero angle is positioned such that it is contact with the valve tip when the cam is on the base circle, (i.e. zero lift). This edit display has an option to import the data directly from a column text file, (this text file could for example be the output from the cam export function).

The example shown here used the direct default module using a base circle radius of 12mm and a maximum valve lift of 3mm. This was exported as an Angle–Radius text file and then imported into the data display, (see below).

{bmc bm45.bmp}
Displaying/Editing the Variable Radius Data

Closing the data display will update the calculation and display such that this defined surface is used as the contact surface between the valve and the follower, (note that the valve origin has been shifted slightly to align the contact point on the base circle and the centre of the valve).

{bmc bm46.bmp}
Graphics Display Showing Defined Variable Radius Follower

As noted previously the zero angle point is always defined as the point that touches the valve tip at the zero lift condition. This zero contact point can be shifted by an offset angle. The offset angle can be edited through the ‘advanced’ button

{bmc bm47.bmp}
Editing the Follower Angle Offset- through ‘Advanced’ button

+$#>Using Individual Exponent Tables

When the profile polynomial is calculated the combination of the segment boundary conditions defined either via ramps or through specific point values, allows the required number of terms in the polynomial to be identified. Each one of the terms in the segments polynomial equation requires a coefficient and an exponent. The Exponents are taken from a table of values whilst the coefficients are calculated. This table of exponents is by default the same for each segment. It is possible for greater control of individual segments to define a lookup table for each segment, (the exception to this is the ramps, that continue to use their own non-editable table).

To change to individual exponents, select from the Solve menu the Use Individual Exponent Tables. This menu option is ‘ticked’ when the segments use their own individual exponents.

The exponents for individual tables are edited in exactly the same way as for the common exponents table through the Poly Expons button on the Profile section’s property sheet. The displayed dialogue box will use a spread sheet style table from the conventional list when using individual segment exponents.

{bmc bm48.bmp}
Individual segment exponent table

The table lists segment number along the top (columns) and exponent no down the side (rows). The first column is the same as used by all the segments when using common polynomial exponents.

It should be remembered that segment one starts at the maximum opening point and not from point 1. If in doubt about segment numbers use the menu item Solve / List Profile Segments to identify which points a segment is associated with.

+$#>Dynamic Exponent Tables

The normal process of editing segment exponents is through the Poly Expons button as discussed in the section above. Whilst this method of editing is suitable for most tasks the option to dynamically change an exponent and view the change is both informative and provides a more intuitive method of manipulating exponents.

To use this utility, select the Solve / Dynamic Exponent Table(s). This opens the dialogue box displayed below.

{bmc bm49.bmp}
Dynamic Exponents Dialogue Box

If you are using ‘individual exponent tables’ then the current segment no is displayed together with ‘arrow’ icons to move between the segments. The sliders indicate the current segments exponent values, those coloured ‘blue’ are the exponents that are actually being used, (i.e. based on the order of the segments polynomial). Selecting a slider allows that particular exponent to be either ‘dragged’ with the mouse or moved up/down via the up and down keyboard arrows. As the exponents are modified so the profile is re-calculated and the display and its results summary refreshed.

The display employs a high/low watermark type mechanism such that the slider will drag the adjoining columns up (or down) if necessary to maintain an increasing relationship.

To re-set the exponents back to the values used when the dialogue box was opened select the Re-Set button. This will lose any changes you made.

To set the exponents to the internally set defaults select the Defaults button.

+$#>User Defined Polynomials

Three default types of polynomial are included within Lotus Concept Valve Train. These are suitable most requirements. Where required the user can define their own polynomial curve using the required number of segments and specified constraints. 

{bmc bm50.bmp}
New Profile selection, for user defined polynomial

To create a user defined polynomial, form the ‘new’ dialogue box select the ‘User Defined Polynomial’ option as indicated above. This will enable the Solve \ Edit User Defined Polynomial menu item. Through this menu item the user can open the dialogue box that allows the user to edit the polynomial settings.

This dialogue box also has a create menu that provides an easy way of starting a user polynomial with simple 2 segment profiles. The ramp sections will be added automatically by the application once you have defined the main event segments.

The normal approach to creating a user-defined polynomial is;

1) set the number of points
2) set the required number of segments
3) define the start and end points for each segment

The first segment should run from the maximum lift point towards the closing side. Subsequent segments should continue until the closing end is reached. Then work from the middle back out to the opening side start point. If in doubt about point / segment ordering either use the create function and review the ordering with these, or look at a standard polynomial structure through the Solve \ List Profile Segments menu item.

{bmc bm51.bmp}
User Defined Polynomial Dialogue Box

Point angles need to be defined relative to a zero value at the maximum opening point with the opening side having –ve cam degrees values and the closing side having positive values. For each point the user can choose for lift and each derivative, (i.e velocity, acceleration and jerk), whether the function is continuous (C) or broken (B) at this point. For each point, (again by derivative), the user can choose if the value is to un-defined (U), defined (D) or Free (F). The difference between ‘Free’ and ‘Un-defined’ is a somewhat arbitrary distinction, it being more normal to use the ‘un-defined’ approach.

Items displayed with a ‘green’ background will have an associated ‘pop-up’ menu that is activated via the left mouse button.

The clear all button will remove all existing point and segment definitions.

+$#>Point Coupling

When editing (or joggling) polynomial points the normal method is to edit each point individually. In some instances it is useful to be able to retain a relationship between points, such that editing one will result in others within a group being set to the same (or mirrored) value. This in essence is the concept behind ‘Point Coupling’.

{bmc bm52.bmp}
Point Coupling Set-up Box

Points are coupled together via the Solve \ Edit Point Coupling menu item. Up to ten groups of coupled points can be defined. For each coupling you must set the number of points in the group, and the derivative that this group should be linked in.

Then set the point numbers to use in the group. The point numbers can be seen drawn next to the markers on the profile graphs. If they are not visible their visibility can be toggled from within this dialogue box via the view menu.

Once a coupling has been defined it to use it you must enable point coupling, again this can be done from within the coupling dialogue box under view menu, or from the main menu item View \ View/Use Segment Point Coupling.

To clear all defined point couplings select the Clear-All button.

For points on the velocity curve that would normally have an opposite sign, this mirroring is preserved.

Currently ‘point-coupling’ makes points in the group have the same value (plus any sign difference), it is envisaged that future versions could work on a retained difference.

+$#>Polynomial Auto-Fit to Imports

The ability to import measured cam data or profile data from component drawings allows the user to assess an existing profile and calculate its kinematic results. In addition the profile can then be exported on for input to other supported applications such as ADAMS/Engine. The import of data is covered in section 8.11.

The ‘Auto-Fit’ solver utility allows the user to fit a standard Concept Valve Train polynomial definition to any imported data, thus enabling cam profile designs based on an imported profile. The fit is based on identifying key features of the profile, (i.e. top of ramp points), and then varying the polynomial exponents to minimise the deviation of the polynomial from the original data.

Control of the auto-fit is based on minimising the deviation of the derived polynomial to the original data. This fit can be controlled through a series of user settings that can set the degree of the fit, which derivatives to include; the weighting of each derivative the number of iterations and tolerances. The settings for the auto-fit are accessed through the Solve \ Auto-fit Settings.. menu item.

{bmc bm53.bmp}
Auto-fit Settings dialogue box

The individual items in the settings box are described below;

Set Check: Tick which derivatives you require to be considered in the fitting process
Auto-Weight: Check this box to use the internal weighting values when summing total deviation of the polynomial from the input data. If this box is unchecked then enter the required weighting values into the Weighting boxes.
Power: Sets the order of the least fit, i.e. 2 = least squares.
Fit Level: Controls the level of auto-detection applied to the fitting process. Default is ‘full’ which includes detection of ramps, mid points, flat topped acceleration curves etc. This would normally be left as ‘full’ unless specific examples require disabling of these auto-detect features.
Re-Set Coefficients: If this item is checked then before the start of the fitting process the segment size and smoothing values are reset to the internal defaults.
Const Vel. Tol: Sets the value used by the auto-detect routines for identifying a constant velocity portion. This tolerance is defined as Vmax/Tolerance Value.
Const Accl. Tol: Sets the value used by the auto-detect routines for identifying a constant acceleration portion. This tolerance is defined as Acceleration Max/Tolerance Value. 
Skip Accel Pts: Sets the number of points at either end of the acceleration curve that are ignored when summing the deviations. This helps alleviate poor fitting due to ill-conditioned end point fits.
Skip Jerk Pts: Similar to above, Sets the number of points at either end of the jerk curve that are ignored when summing the deviations. This helps alleviate poor fitting due to ill-conditioned end point fits.
No. of Iterations: Sets the number of times that the auto-fit solver passes through the exponent loop.

You can only run the auto-fit process once the profile data has been imported. The auto-fit process will use whichever polynomial template type is currently set. The auto-detect polynomial type feature is not yet enabled.

To run the auto-fit process select Solve \ Auto-Fit Polynomial to Data. As the process runs the graphical display is updated illustrating the progress made with the fit. Once the fit is complete the ‘auto-fit’ message box will disappear.

{bmc bm54.bmp}
Auto-fit Message box

At the end of the process the polynomial curve is shown compared to the original data, (red line). If the fit is not acceptable the user should adjust the fit settings, re-load and re-run.

#>Edit Data Icon {bmc bm55.bmp}

#>Joggle Data Icon {bmc bm56.bmp}

#>Solve Update Icon {bmc bm57.bmp}

#>{bmc bm58.bmp}
#>Clip and Replace Mode Icon {bmc bm59.bmp}

#>Edit Settings Icon {bmc bm60.bmp}

+$#>Icon Description – General

The following icons are displayed on the main toolbar. A brief description is given for each.

{bmc bm61.bmp} Create New File

{bmc bm62.bmp} Open Existing Data File

{bmc bm63.bmp} Save Data to File

{bmc bm64.bmp} Save As Data to File

{bmc bm65.bmp} Export Data to File

{bmc bm66.bmp} Return to Engine Simulation Environment

{bmc bm67.bmp} Launch ADAMS/Engine

{bmc bm68.bmp} Visit Lotus Engineering on the world wide web

{bmc bm69.bmp} On-Line Help

{bmc bm70.bmp} Help About

+$#>Icon Description – Profile Section

The following icons are displayed on the main toolbar. A brief description is given for each.

{bmc bm71.bmp} Display all profile graphs

{bmc bm72.bmp} Set to Edit Data Mode

{bmc bm73.bmp} Set to Joggle Data Mode

{bmc bm74.bmp} Set to Drag Data Mode

{bmc bm75.bmp} Replace Point by Interpolation

{bmc bm76.bmp} Add Bezier control point to Current Segment

{bmc bm77.bmp} Delete picked Bezier control point from Segment

{bmc bm78.bmp} Sets current Bezier Segment

{bmc bm79.bmp} Sets current Bezier edit type to both x any positional

{bmc bm80.bmp} Sets current Bezier edit type to x positional only

{bmc bm81.bmp} Sets current Bezier edit type to y positional only

{bmc bm82.bmp} Sets current Bezier edit type to length only

{bmc bm83.bmp} Sets current Bezier edit type to slope only

+$#>Icon Description – Mechanism Section

The following icons are displayed on the main toolbar. A brief description is given for each.

{bmc bm72.bmp} Set to Edit Data Mode

{bmc bm73.bmp} Set to Joggle Data Mode

{bmc bm74.bmp} Set to Drag Data Mode

{bmc bm84.bmp} Set to 3D Viewing Mode

{bmc bm85.bmp} Dynamic Translate Mode

{bmc bm86.bmp} Dynamic Zoom Mode

{bmc bm87.bmp} Dynamic Rotate Mode

{bmc bm88.bmp} Animation – Rewind Mode

{bmc bm89.bmp} Animation – Reverse Mode

{bmc bm90.bmp} Animation – Back one Frame

{bmc bm91.bmp} Animation - Stop

{bmc bm92.bmp} Animation – Forward one Frame

{bmc bm93.bmp} Animation – Play Mode

{bmc bm94.bmp} Animation – Fast Forward Mode

+$#>Icon Description – Statics Section

The following icons are displayed on the main toolbar. A brief description is given for each.

{bmc bm71.bmp} Display all Valve Train Statics Graphs

+$#>KIcon Description – Valve to Piston Clearance Section

The following icons are displayed on the main toolbar. A brief description is given for each.

{bmc bm71.bmp} Display all Piston Clearance Graphs

{bmc bm72.bmp} Set to Edit Data Mode

{bmc bm73.bmp} Set to Joggle Data Mode

{bmc bm74.bmp} Set to Drag Data Mode

+$#>Icon Description – Spring Design Section

The following icons are displayed on the main toolbar. A brief description is given for each.

{bmc bm72.bmp} Set to Edit Data Mode

{bmc bm73.bmp} Set to Joggle Data Mode

{bmc bm74.bmp} Set to Drag Data Mode

{bmc bm85.bmp} Dynamic Translate Mode

{bmc bm86.bmp} Dynamic Zoom Mode

+$#>KIcon Description – Overlap Section

The following icons are displayed on the main toolbar. A brief description is given for each.

{bmc bm72.bmp} Set to Edit Data Mode

{bmc bm73.bmp} Set to Joggle Data Mode

{bmc bm74.bmp} Set to Drag Data Mode

{bmc bm71.bmp} Display all Overlap Graphs

+$#>Icon Description – Dynamic Spring Section

The following icons are displayed on the main toolbar. A brief description is given for each.

{bmc bm72.bmp} Set to Edit Data Mode

{bmc bm85.bmp} Dynamic Translate Mode

{bmc bm86.bmp} Dynamic Zoom Mode

{bmc bm91.bmp} Animation - Stop

{bmc bm92.bmp} Animation – Forward one Frame

{bmc bm93.bmp} Animation – Play Mode

{bmc bm94.bmp} Animation – Fast Forward Mode