Estimation of the tribotechnical parameters of the "piston skirt-cylinder liner" contact interface from an IC-engine for decreasing the mechanical losses

Abstract

To decrease mechanical losses in internal combustion engines (ICE) a deeper understanding of the friction and wear processes in the main tribosystems is necessary. In particular, the interrelation between frictional energy and wear has to be analyzed. For this reason the hard to measure quantity of coefficient of accumulation of frictional energy, which is a pivotal parameter in some energy based wear theories, is determined in this work using model tribometer experiments. The experiments are performed using small specimens made of aluminium silicon alloy and gray cast iron with a SRV tribometer (linear reciprocating motion) where loading and lubrication conditions which closely simulate the real contact situation of a piston skirt sliding against a cylinder liner near the top dead center are applied. To calculate the coefficient of accumulation of frictional energy, experimentally gained values for the linear integral intensity of wear are analyzed numerically for various loading parameters (normal load, sliding speed, conditions of lubrication) which result in variation of the coefficient of friction and in the amount of wear. Finally the results of the correlation between the coefficient of accumulated energy in the piston skirt-cylinder liner tribosystem and the loading conditions are presented. Furthermore some recommendations for technical solutions to decrease mechanical losses in the investigated system are given. © 2014 WIT Press.