PISTON SECONDARY MOTIONS AND HYDRODYNAMIC LUBRICATION REGIME IN A SINGLE CYLINDER INTERNAL COMBUSTION ENGINE

A major portion of the frictional losses in internal combustion engines has been attributed to the piston-assembly. The current work examines the piston secondary motions and the relationships with which they interact with the lubricating oil film. This is done by developing a model that accounts for the rigid and flexible motions of the crank-slider mechanism of a single cylinder engine. The model considers the secondary motions of the piston and has a variable structure, which allows for the number of degrees of freedom of the system to vary depending on the nature of contact between the piston and the liner The 3-D Reynolds' equation is used to determine the instantaneous oil pressure, which is needed for the computation of the normal and the hydrodynamic friction forces exerted on the piston-assembly. The simulation results demonstrate the capability of the model in predicting the hydrodynamic friction force, the piston secondary motions, and the instantaneous oil film thickness.