Abstract: In current lubrication analysis of piston skirt, the piston skirt-cylinder liner frictional pair is usually supposed to be lubricated sufficiently in all strokes of an operating cycle of internal combustion engine. In fact, the status of sufficient lubrication of this frictional pair may not be guaranteed by the actual quantity of lubricating oil at entrance during the piston upstroke. Based on the model of piston secondary motion, the model of fluid lubrication and the model of lubricating oil flow, the quantity of lubricating oil stayed on the cylinder liner during the downward movement of piston skirt is calculated, and then the lubrication of piston skirt-cylinder liner frictional pair is analyzed under the condition that the quantity of lubricating oil stayed on the cylinder liner is taken as the entrance quantity of lubricating oil during the piston upstroke. The results show that compared with the current analysis in which the sufficient lubrication in all strokes is assumed, the lubrication performance of piston skirt-cylinder liner frictional pair and the piston secondary motion are changed obviously when the lubrication status of frictional pair during piston upstroke in the lubrication analysis of piston skirt is determined by the actual transport of lubricating oil.

Key words: internal combustion engine;piston skirt;cylinder liner;lubrication;transport of lubricating oil