Tribological analysis on the effect of heat transfer towards engine in-cylinder friction

Abstract

The aim of this study is to determine the effect of heat transfer towards engine in-cylinder frictional losses, generated by the piston ring pack sliding along the engine cylinder liner. A mathematical model is derived from the 1D Reynolds equation, using Reynolds’ boundary condition, to determine the contact pressure distribution along the ring-liner conjunction. Meanwhile, the lubricant temperature profile is solved using the 1D energy equation, considering heat conduction and viscous heating effect. The mathematical models are implemented in C-program. The minimum film thickness and the total friction force from the current model are showing good correlation with literature data. The results showed that heat conduction mechanism predominates the viscous heating effect in the ring-liner conjunction. Meanwhile, the boundary friction predominates the contribution of viscous friction, especially along the vicinity of dead centres. However, the boundary friction is not affected by the changes in lubricant viscosity. Hence, from an overall engine operation point of view, the effect of heat transfer towards the total friction force generated by the ring pack could be considered trivial.