柴油机活塞裙面型线设计分析

Analysis and design of diesel engine piston skirt profile

为得到活塞裙面型线设计中不同因素的影响权重及显著性,选取活塞裙面型线中凸型线顶端内缩量、底端内缩量、中凸点高度及变椭圆度系数等参数,设计正交试验方案,应用三维结构动力学分析软件,研究不同活塞裙面型线设计方案下的活塞裙部-缸套间的润滑及振动特性。分析结果表明:活塞裙顶端内缩量对最小油膜厚度存在显著影响,中凸点高度和底端变椭圆度系数为摩擦功耗的影响因子,而顶端变椭圆度系数对缸套振动特性的影响高度显著;综合考虑活塞裙部润滑特性和缸套振动特性,得到活塞裙面型线最优设计方案,活塞裙底部缩进量为0.08 mm,活塞裙顶端内缩量为0.15 mm,中凸点高度为27 mm,变椭圆度系数a为0.45,变椭圆度系数b为0.0028。

In order to obtain the influence weight and significance of different factors in the design of piston skirt profile,the orthogonal test scheme is designed by selecting the parameters such as the top shrinkage,the bottom end shrinkage,the height of middle convex point and the variable ellipticity coefficient.The lubrication and vibration characteristics between piston skirt and cylinder sleeve under different design schemes of piston skirt profile are studied by using 3D structural dynamics analysis software.The results show that the reduction of the piston skirt top has a significant effect on the minimum oil film thickness,the height of the middle convex point and the variable ellipticity coefficient of the bottom end are the influence factors of the friction power consumption,while the top variable ellipticity coefficient has a significant impact on the vibration characteristics of the cylinder liner.Considering the lubrication characteristics of the piston skirt and the vibration characteristics of the cylinder liner,the optimal design scheme of the piston skirt contour is obtained.The reduction of the bottom of the piston skirt is 0.08 mm,the internal shrinkage of the top of the piston skirt is 0.15 mm,the height of the middle convex point is 27 mm,the variable ellipticity coefficient a is 0.45,and the variable ellipticity coefficient b is 0.0028.