A study of the secondary piston motion arising from changes in the piston skirt profile using a simplified piston skirt model

Abstract

An existing model of the interface between a parallel-sided piston skirt and the cylinder wall in an internal combustion engine is extended to allow the modelling of barrelling of the piston skirt. The effects of the skirt profile on the secondary motion of the piston and on the distribution of pressure in the lubricant film are examined. It is shown that piston secondary motion, and in particular rotation of the piston about the gudgeon pin, which might contribute to wear of the cylinder, can be reduced by appropriate positioning of the maximum diameter of the piston skirt in relation to the gudgeon pin and the centre of mass of the piston.