高强化汽油机活塞裙部支撑疲劳开裂分析及结构改进

Analysis and improvement of piston skirt support fatigue cracking for a high strength gasoline engine

针对某增压直喷高强化汽油机活塞在试验过程中出现的裙部支撑部位开裂问题,分析活塞材料、发动机运行过程及活塞结构强度,确定设计强度不足是裙部支撑部位开裂的主要原因,并对活塞销座两侧支撑部位进行改进优化。利用有限元仿真分析方法对设计优化方案进行模拟计算,结果表明:改进活塞裙部下端支撑筋的厚度及高度后,裙部下端支撑部位的疲劳系数可提高一倍以上;改进后的活塞样件顺利通过发动机耐久试验,验证了改进优化的有效性。该优化可以有效解决活塞裙部支撑部位开裂的问题,为增压直喷高强化汽油机活塞在该部位的细节设计及失效改进提供参考。

The piston material,engine running parameters and piston structural strength are analyzed in order to determine the main cause of the piston skirt support cracking for a turbocharged direct injection gasoline engine.It is determined that the design strength is the main reason for the skirt support part to crack,and the support parts on both sides of the piston pin seat are improved and optimized.The FEA is used for simulation and calculation.The results show that the fatigue factor is increasd more than double by strengthening the height and thickness of the skirt support.The improved pistons pass the engine endurance test successfully.The design optimization solves the problem of piston skirt support cracking effectively,it can provides a reference for the high strength gasoline engine piston design.