A Numerical Approach to Predict Roller Follower Valve Trian Frictional Torque Considering the Effects of Roller Sliding

The efficiency and reliability of engine parts are largely governed by friction. The valve train assembly is considered one of the extremely difficult assemblies in terms of its tribological performance and is often subjected to severe and unsteady functional conditions leading towards friction and wear of components. In this research work, a comprehensive numerical approach addressing mixed lubrication theory will be presented to investigate the frictional performance of a roller follower valve train system considering the impact of roller sliding, asperity interaction and friction arising from associated components under different operating conditions. A direct relationship between total drive torque and camshaft rotational frequency has been found predicting an increase in sliding friction due to roller slip on the camshaft surface. Relatively greater magnitude of roller sliding was observed in cam flank regions resulting in high sliding friction. A rise in hydrodynamic friction was found due to the shearing of a relatively thick oil film at a low lubricant supply temperature.