An Automotive Piston Lubrication Model

An analytical study of the dynamics of a piston in a reciprocating engine was conducted. The analysis, which incorporates a hydrodynamic lubrication model, was applied to a V-8 automotive spark ignition engine. The variation of piston transverse position and rotation with crank angle, and the piston-skirt frictional power loss were calculated for different wrist pin locations, piston-to-cylinder clearances, and lubricant viscosities. The results obtained indicate that piston motion is strongly affected by the location of the wrist pin and that piston-skirt friction is increased significantly if the wrist pin is at an unfavorable position. In addition, piston dynamics were found to be sensitive to piston-cylinder bore clearance and lubricant viscosity, underscoring their importance in engine design.