Elastohydrodynamic lubrication analysis of cam-roller pairs of internal combustion engines

Abstract

Based on the cam-roller pair of an internal combustion engine, a mathematical model of transient thermal elastohydrodynamic lubrication under finite line-contact and the corresponding numerical solver have been established. Under an actual load spectrum and other working parameters from an industry partner, the detailed lubrication performance of the cam-roller pair has been obtained in a cam rotation cycle. Particularly, the influences of the roller convexity, the roller tilting and the skidding between cam and roller on the contact pair lubrication are presented. The lubrication performance of the cam-roller pair depends on the roller convexity markedly, and an optimal roller convexity can effectively reduce the probability of the lubrication film rupture and improve the uniformity of pressure distribution in the contact zone. The roller tilting can worsen the lubrication of the contact zone, and increase the possibility of lubrication failure. If the tilting is taken into consideration at the beginning of the roller convexity design, its negative effect can be effectively alleviated to a certain extent. The skidding results in noticeable increase in temperature and friction coefficient, which can deteriorate the contact zone lubrication. The results provide some theoretical data basis for the lubrication design of cam-roller pairs.