Analysis and Customization of Rocker Arm Joint Sliding Velocity

This paper examines how the sliding motion between a rocker arm and a valve stem tip can be adjusted by reshaping the rocker pad surface. The valve tip is assumed flat, and the rocker arm and valve stem are assumed to lie in a common plane. It is shown that the rubbing velocity between a rocker arm and a valve stem tip, as well as the curvature of the rocker arm pad, may be determined from two features of the contact: (1) the contact point path between the rocker arm and the valve stem tip and (2) the angle that the valve stem tip makes with the line connecting the rocker pivot to the zero-lift point of contact. An algorithm is presented for determining a rocker arm surface from a prescribed contact point path and valve angle. The derived technique enables customization of rocker arm pad curvature and rocker arm joint sliding velocity.