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建立了内燃机活塞二阶运动数学模型,建模时综合考虑了活塞裙部外形轮廓、活塞裙部和缸套的热变形和弹性变形、表面波度和粗糙度以及裙部润滑摩擦状况等因素。利用该模型对一些活塞参数进行了仿真设计,为活塞--缸套系统优化设计提供指导。结果表明活塞裙部长度过短,可导致活塞二阶运动增大;活塞销偏心距过大会使活塞摩擦功耗和二阶运动快速增加;配缸间隙最佳值位于二阶运动曲线和摩擦功耗曲线的交点区域;确定径向缩减量时,应先确定裙部上端的径向缩减量。“,”A mathematical model for piston secondary motion of combustion engine was developed.It took into account the effects of the topography of the skirt,thermal distortion and bulk elastic deformation of piston skirts and cylinder bore,surface waviness and roughness,lubrication and friction.The model was used to simulate some design parameters of piston and a set of quantitative design guidelines for piston assembly was provided.The results show that secondary motion of piston becomes larger because of over short piston skirt.The larger wrist pin offset causes rapid increase of secondary motion and friction power loss of piston.The optimum radial clearance between piston and cylinder bore is at the intersection of the secondary motion curve and the friction power loss curve.To confirm radial reduction of piston skirt,the top radial reduction of piston skirt should be determined first.