内燃机气缸套失圆对活塞动压润滑和摩擦特性的影响

Influence of Cylinder Liner Out-of-Roundness on Dynamic Lubrication and Friction Characteristics of Piston

根据流体动力润滑理论与活塞动力学方程建立了相关分析模型,在考虑内燃机工作过程中实际存在的气缸套失圆变形基础上,分析了活塞的横向运动,考察了活塞裙部的压力场和摩擦特性.结果表明:与不考虑失圆变形时相比,考虑失圆变形时的润滑油膜压力场的峰值降低,裙部流体压力负荷得以缓解;考虑失圆变形后的摩擦力和摩擦功耗增大,失圆程度越大,所产生的摩擦力和摩擦功耗的增量越大.因此,在活塞设计过程中应当重视失圆变形对活塞裙部润滑和摩擦特性的影响.

The pressure fields and friction forces at the skirt of the piston were analyzed by using relevant mathematic models based on hydrodynamic lubrication theory and piston dynamics. Thus the transverse movement of the piston was analyzed and the pressure field and friction forces at the skirts of the piston were calculated by taking into account the out-of-roundness of the cylinder liner produced in the running of the gasoline engine. The results indicated that the peak value of the pressure field of the oil film decreased and the friction forces at the piston skirt increased after considering the out-of-roundness of the cylinder liner. The larger the degree of the out-of-roundness of the cylinder liner, the larger the increments of the friction force and friction power consumption. Thus it was imperative to take into account the effect of the cylinder liner out-of-roundness on the lubrication and friction characteristics of the piston skirt in the design of the piston.