LUBRICATION AND SLIPPAGE IN ROLLER FINGER FOLLOWER SYSTEMS IN ENGINE VALVE TRAINS

To predict the performance of the energy-efficient finger follower system with a roller follower requires an adequate understanding of the kinematics and forces in the roller cam contact. This paper analyzes the kinematics, lubricant film thickness and normal/friction tractions in the finger follower and the roller itself. The analysis includes the EHD tractions, hydrodynamic rolling friction and bearing torque to determine the cam-roller slippage and tractions for various positions of a cam cycle. For a roller finger follower and a sliding finger follower of similar design, a comparison is given for the calculated EHD film thickness and power losses in various parts of the tappet.