活塞裙部流体动力润滑数值分析

对内燃机活塞-缸套系统的流体动力润滑与动力学行为进行了耦合分析,在考虑活塞二阶运动的基础上建立了活塞裙部润滑的数值模型。运用龙格-库塔方法求解二阶运动模型,并采用有限元方法求解裙部润滑的平均雷诺方程。分析了裙部不同型线、活塞销不同偏置的油膜厚度、油膜压力和活塞摆角等二阶运动状况。在润滑油不同粘度以及是否考虑粘压特性条件下,对油膜摩擦力和摩擦功率进行了对比。结果表明,裙部采用中凸椭圆型线,活塞销向主推力侧偏置,可减小二阶运动,改善润滑状态,润滑油粘度对裙部摩擦损失有较大的影响,而粘压特性则对裙部润滑的影响较小。

Numerical Analysis of Piston Skirt Hydrodynamic Lubrication

The coupling effect between the lubricating behavior and dynamic behavior of a cylinder-piston system in an internal combustion engine was analyzed.A piston skirt lubrication numerical model in running conditions was established considering the effect of piston secondary motion.The Runge-Kutta method was used to solve the secondary motion model and the FEM was applied to solve the average Reynolds Equation.Oil film thickness distribution,oil film pressure and secondary motion status such as the piston swing angle were calculated under different skirt profile and different pin offsets.Also the oil film friction force and friction power loss under different viscosities or considering pressure-viscosity relation were present.It shows that elliptical skirt profile,piston pin to reset major thrust side can reduce the secondary motion and improve lubrication.Viscosity has a greater impact on skirt friction losses,while the pressure-viscosity relation has less on skirt lubrication.