在考虑连杆惯性的基础上，根据活塞的力和力矩平衡建立活塞的二阶运动模型。在对活塞-缸套系统的混合润滑和活塞动力学行为进行耦合分析的基础上，研究活塞裙部纵向、横向型线、活塞销偏置和热变形对裙部摩擦学性能的影响。运用FDM求解裙部润滑的平均Reynolds方程，在此基础上，运用Runge-Kutta法求解活塞的二阶运动轨迹。在综合考虑连杆惯性、活塞裙部和缸套表面粗糙度的基础上，研究了活塞纵向、横向型线、活塞销偏置和热变形对活塞裙部二阶位移、速度和摩擦功耗等的影响。数值结果表明，连杆惯性力对活塞裙部摩擦特性的影响较大。当中凸变椭圆活塞采用纵向抛物线型轮廓，分别取较小的上端椭圆度和较大的下端椭圆度，较小的上端径向缩减量和较大的下端径向缩减量，并将活塞销向主推力边偏置时，可减小二阶运动幅值和速度，同时增大裙部润滑油膜厚度，减小活塞-缸套系统的摩擦功耗。研究为考虑活塞裙部热变形的轮廓型线设计提供了依据，可进一步改善活塞-缸套系统的摩擦学性能。
吕延军, 李猛, 张永芳, 刘万万, 严冬
. 轮廓参数对活塞二阶运动和裙部润滑性能的影响研究[J]. 机械工程学报, 2018
, 54(15)
: 100
-116
.
DOI: 10.3901/JME.2018.15.100
The secondary motion of piston is modeled by considering the inertia of connecting rod according to the balance of the forces and moments acting on the piston. The influence of the structural parameters of the piston skirt longitudinal molded lines, the horizontal molded lines, the offset of piston pin and the thermal deformation on tribological properties of the piston skirt is investigated by considering coupling of the mixed lubrication of the piston-cylinder liner system and the dynamic behaviors of the piston. The average Reynolds equation of skirt lubrication is solved with FDM, and then the secondary motion trajectory of the piston is calculated by Runge-Kutta method. The influence of the piston skirt longitudinal molded lines, the horizontal molded lines, the offset of piston pin and the thermal deformation on the displacements and velocities of secondary motion, and friction power consumption is investigated by taking the inertia of the connecting rod, the surface roughness of the piston skirt and cylinder liner into consideration. The numerical results show that the inertia force of the connecting rod has important influence on the tribological property of the piston skirt. When the parabolic longitudinal molded line is applied for the middle-convex and varying ellipse piston, the amplitude and velocity of the secondary motion can be reduced. When the top and bottom ellipticities of the middle-convex and varying ellipse piston are chosen as smaller and bigger values respectively, the top and bottom radial reductions are chosen as smaller and bigger values respectively, the amplitude and velocity of the secondary motion can be also reduced. When the offset of piston pin is put to the thrust side slightly, the amplitude and velocity of the secondary motion can be also reduced. Meanwhile, the oil film thickness is increased, and the friction power consumption of the piston-cylinder liner system is reduced. The proposed model and numerical results can provide a theoretical direction to the design of piston skirt molded lines and further improvement of tribological properties of the piston-cylinder liner system.
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