ANALYSIS OF TRANSIENT MINIMUM FILM THICKNESS IN CAM AND FLAT FOLLOWER 2000-05-0163

In order to verify the characteristics of frictional resistance and wear in valve train components, it is the basic investigation to find the minimum film thickness of contacting components. This verification gives useful clue for better performance and endurance life of the whole engine system. The applied loads and the relative contacting velocities during the cycle are obtained from the simulation of kinematics and dynamics of push-rod type valve train system. The contact geometry between cam and follower is very non-conformal that results in concentrated fluid film pressure and very high-stress on the contact region. Both loads of high fluctuation and relative sliding velocities of sudden change in cam and follower contact frequently make it impossible to get both converged and stable solutions with conventional numerical method. Multigird multi-level method for the solver of non-linear partial differential equation including solid deformation is used in our study for the numerical convergence and stability. With this numerical algorithm, the minimum film thickness under dynamic loading condition is computed and compared to that of steady loading condition and Dowson-Hamrock curve fitting formula. In our work, we developed computation tools both for kinematics and dynamics of valve train system of push-rod type and for fluid film thickness with elastic deformation on the basis of dynamic loading condition with multigrid multilevel method.