某增压发动机缸盖热机疲劳分析

Thermal Fatigue Analysis of a Turbocharged Engine Cylinder Head

我们针对增压发动机的缸盖热机疲劳破坏问题进行了系统模拟分析,通过对发动机全负荷-部分负荷-怠速工况的循环加载,系统地研究了缸盖在交变循环热载荷下的抗疲劳特性,并得出主要结论。首先位于缸盖水套内进排气气门之间的冷却液易产生泡核沸腾现象,影响缸盖该区域结构的散热性能;其次缸盖水套内进气气门倒角区域的疲劳安全系数低于设计限值,易产生疲劳裂纹,建议增大该区域倒角半径,同时增加该区域水套壁厚;最后缸盖上电热塞位置的累积塑性应变值最大,达到0.73%,但仍低于1%的安全限值。

In this paper, the thermal fatigue damage problem of the turbocharged engine cylinder head is systematically simulated. By loading the thermal cycle load of full charge, partial loading and idling mode, the high and low cycle fatigue characteristics of the cylinder head is analyzed and arrives at some conclusions： First, the cooling water between the intake valve and the exhaust valve of the cylinder head water jacket is prone to nucleate boiling, which affects the heat dissipation performance of the cylinder head; Second, the fatigue safety factor of the intake valve chamfer area of water jacket is lower than the design limit which is easy to crack and it is suggested to increase the chamfer radius and the thickness of the water jacket; Finally, the accumulative plastic strain of the plug on the cylinder head is the largest, reaching 0.73%, but still less than the safety limit 1%.