Setting up the Valve Motions

For the motion of the valves, you import tables that describe the valve lifts in mm as functions of degree crank angle. If the imported table values do not represent the real valve lifts, you can correct the valve lift curves here.

Additionally, you can move the position of the valve curtain interface. In general, you are advised to only modify the location of the valve curtain interface if you encounter one of the following problems:
  • CAD errors, such as invalid CAD
  • Mesh errors, such as negative volume cells
  • Bad convergence
To define the motion for a valve:
  1. Right-click the respective Engine > Exhaust Valve [n] or Intake Valve [n] node and select Edit.
  2. Within the Edit dialog, in the Motion tab, click Import next to the Valve Lift File drop-down menu.
  3. In the Import Valve Lift Table dialog, navigate to the valve lift table.
  4. Select the table and click Open.
    In the Graphics window, a Valve Lifts plot opens, which displays the valve lifts as a function of crank angle.
  5. To correct the valve lift curve, set the following properties:
    • Lash
    • Cycle Anchor
    • Profile Anchor
    • Lift Multiplier
    • Duration Multiplier
    The Valve Lifts plot updates to display the corrected curve.
  6. Set Closure Tolerance to the valve lift that corresponds to a closed position.
  7. Specify the Interpolation Method that is used to interpolate between the data points of the valve lift table—Linear or Cubic (Akima).
  8. To control what is displayed in the Valve Lifts plot, set the following properties:
    • Show Table
    • Show Lift
    • Show Velocity
    • Show This Valve Only
  9. Click Apply.
    Note that closing the Edit dialog resets the plot properties as specified in Step 8 to their default settings.
To move the location of the valve curtain interface:
  1. Click the Mesh Settings tab.
  2. Set Normalized Curtain Interface Position as a percentage of the valve's Face radial distance.
  3. Click Apply, then Close.
    For more information, see Engine Reference—Valve Dialog.
The imported valve lift table and the specified properties define the motion of the valve. When you run the simulation, Simcenter STAR-CCM+ In-cylinder uses these data to calculate the valve position for the respective crank angle and updates the geometry accordingly. However, as long as you do not start the simulation, the Graphics window displays the valve in its closed position. In the bottom left corner, the red-colored starred text indicates that the displayed valve is not at its correct position for the displayed crank angle. Additionally the warning triangle () on the Engine > Exhaust Valve [n] node indicates that this Engine Part requires an update.
  1. If you want to visualize the valve position according to your settings, click Update.