Kinematic Analysis of a Circular-Arc Cam with Roller Follower Case Study: Cam for Controlling Intake Valve in an I.C.E

Abstract

In this research, a kinematic analysis of a circular arc cam with radial reciprocating roller follower has been carried out. The relationships of displacement, velocity and acceleration of the follower on the face arc and nose in terms of the angle of rotation of the cam have been derived. The derived relationships allowed easily to transit to the same cam with both knife-edge and flat-faced followers without new mathematical derivation. Charts of motion are drawn in terms of the angle of rotation of the cam, in order to evaluate its performance kinematically. Sudden changes in acceleration during both the lift and down strokes lead to creation of variable inertia forces in value and direction, causing shock loads that affect the cam mechanism. To evaluate the effect of the radius of the spherical follower on the acceleration change, this research examined a numerical example of a cam that is used to control the opening and closing the intake valve in a four-stroke ICE. A comparison of cam performance was performed with both spherical and flat followers, in order to assess the optimum values for the radius of the spherical follower that gives less sudden change in acceleration.