Numeric based low viscosity adiabatic thermo-tribological performance analysis of piston-skirt liner system lubrication at high engine speed

摘要

In conjunction with lubricant oil film dynamics, automotive piston's primary and secondary motion indicatively affect the engine noise and frictional losses (fuel economy). The escalation of oil film temperature due to adiabatic shear heating of low viscosity Newtonian lubricant oil film affects the load carrying capacity and viscosity of lubricating film and enhances friction losses, piston wear, and non-linear lateral motion of piston. In this study, a numerical model for piston dynamic and lubrication is presented, in which adiabatic heating effects are simulated in hydrodynamic mixed lubrication regime by coupling with 2D-energy equation. The thermo-hydrodynamic lubrication model is solved using finite difference formulation, while the piston dynamic model is solved using the modified Newton Raphson method. Furthermore, the effect of adiabatic shearing of lubricant and piston skirt design parameters on piston dynamics and lubrication performance are analyzed. Results show that the adiabatic heating significantly affects piston lateral motion and lubrication performance. Lubrication analysis is very beneficial in the improvement of engine design of piston skirt-liner and can help reduce the friction losses.