Experimental measurement and modelling of plain bearing wear in start–stop applications

Abstract

The implementation of CO₂ saving technologies such as start–stop has introduced new constraints on the engine bearings and their operating environment. The number of expected start–stops of a modern hybrid engine has risen to about 1.2 million for the engine lifetime. Frequent operation under mixed and boundary lubrication regimes may noticeably increase wear and reduce the life of the bearings. The developed test rig and modelling software are capable of simulating engine transient working conditions. The test results confirmed higher wear resistance of a bearing with a polymeric overlay working under start–stop conditions in comparison to an aluminium bimetallic bearing. Simulation results calculated on the basis of the ‘Direct Contact Reaction’ and correlated with the experimental data made it possible to estimate the wear of the bearings working in different start–stop applications.