Coupled Analysis of Piston Mechanism and Lubrication (Numerical Calculation of Piston Skirt Friction)

Abstract

In this study, we have developed a coupled analysis method of piston dynamics and lubrication. The kinematic motion and structural vibration are calculated by the flexible multibody dynamics theory developed in the former study. The mixed lubrication film between the piston skirt and the cylinder bore is numerically modeled as a force element. The hydrodynamic pressure and the friction force in fluid lubrication region on this interface are solved by a finite difference method. The contact pressure and the friction force by solid contact are calculated by the statistic asperity contact model. This mixed lubrication model is validated by a reciprocating friction tester. Then, we apply this method to the estimation of the friction force measured by a floating liner type friction tester at firing condition, and clarify the contributions of hydrodynamic and solid contact on the friction force.