A Piston Lubrication Model Considering the Coupling between the Piston Secondary Motion and the System Inertia Variation in an IC Engine

Abstract

With increasing public concern about the environmental problems and oil prices, improving fuel economy and reducing engine emissions in modern passenger car engines has become one of the important trends in engine design. It is currently estimated that the piston — cylinder bore friction accounts for up to 25% of the power loss in a typical engine. The piston secondary motion has a significant influence on the major characteristics of lubrication in internal combustion engine, such as the oil leakage, the piston slap phenomenon and the frictional power loss. Therefore, better understanding and more accurately modeling piston dynamics play an important role in piston design for the reduction of friction to improve fuel economy and to reduce exhaust emissions. This paper presents a new model of piston secondary motion with consideration of the effect of system inertia variation. According to this model, it is found that the piston side force dominates piston secondary motion, and system inertia variation has an important effect on the piston side force, so it greatly influences the piston secondary motion. Also, the effects of system inertia variation on the friction and lubrication behavior between piston skirt and cylinder liner are investigated in this study.