Numerical simulation of the effects of coating on thermal elastohydrodynamic lubrication in cam/tappet contact

Abstract

Investigating the effects of coating on cam/tappet thermal elastohydrodynamic lubrication through numerical simulation has great significance in the design of coated cam/tappet conjunctions. This paper presents a numerical model for the prediction of the thermal elastohydrodynamic lubrication of a coated cam/tappet and the results of a study of the effects of coating parameters on cam/tappet lubrication performance. In the model, the Reynolds equation is solved by the damped Newton method to obtain the pressure distribution, and energy equations are used to obtain the temperature distribution. The total elastic deformation is calculated by the finite element method. The effects of the coating’s mechanical properties on pressure and temperature were found to be significant, as were the effects of the coating’s thermal properties on temperature. These effects were found to increase with increasing coating thickness. A soft coating with low thermal inertia has the greatest ability to reduce friction loss, and the higher the inlet temperature is, the lower the friction loss is. The influence of coating of both the cam and tappet on friction loss is greater than the effect of coating of the tappet only, which is greater than the effect of coating of the cam only.