Cam-operated valve example

Objectives

• Use a submodel that reads a data file

• Use the Table Editor to preview an existing data file

• Show how to alter some characteristics of a curve

• Create an x-y plot

Figure 88: Valve and valve spring operated by cam

This system represents an automobile engine valve and valve spring assembly operated by an overhead cam. The overhead cam rotates at constant speed defined by the signal source CONS0.

The signal is converted to an angular speed in rev/min by OMEGC0 and supplied to the cam submodel CAM00. This submodel relies on a data file to convert the rotary angular position in degree to a linear cam displacement in m. In other words, the data file defines the cam profile.

The cam linear displacement and velocity are passed into a submodel LSPT00A. This submodel represents the clearance between the cam follower and the top of the valve. When this clearance becomes zero there is a strong spring force and damping force modeling the contact.

LCON12 is an example of a mechanical node and is used to exchange velocities, displacements and forces between the spring submodel SPR000A and the mass submodel MECMAS21. Note that this mass has limitations on its movement. We say it has end-stops.