李炜   

    摘要：针对天然气发动机气缸盖排气孔口产生裂纹这种故障,本文以有限元方法为基础,对某天然气发动机气缸盖建立模型,进行了热-固耦合计算。结果表明正常工作状态下气缸盖温度及压应力最高处发生在排气孔口间"鼻梁处",温度为280℃,压应力为1640MPa。当冷却水侧换热恶化或发动机突加载荷状态下会导致气缸盖工作温度及应力升高,"鼻梁处"温度达到372℃,压应力达到2000MPa,这时气缸盖"鼻梁处"会在高温下产生压塑性变形,导致该处产生裂纹。

    关键词： 气缸盖;有限元分析;热-固耦合分析

    Abstract: In view of cylinder head crack that happened in the natural gas engine,this paper built a model for the cylinder head with finite element method,and made a thermo-structural coupling calculation.The results showed that the maximum temperature and stress occurred at the valve bridge region between of exhaust valves when the cylinder head was working under normal working conditions.Its maximum temperature was,and the maximum stress was 1640MPa.When heat transfer of cooling water got degraded or the engine load changed suddenly,the temperature of the cylinder head in this region would increase to and its stress reached 2000MPa,therefore,the valve in bridge region would get deformed due to high temperature and further was cracked.

     Keywords: Cylinder Head;FEA;Thermo-structural Coupling Analysis

参考文献:

[1]镇江农业机械学院.内燃机构造[M].北京:中国农业机械出版社,1981.

[2]陆瑞松.内燃机的传热与热负荷[M].北京:国防工业出版社,1988.

[3]陈特峦.内燃机热强度[M].北京:国防工业出版社,1991.

[4]潘剑锋.多缸柴油机气缸盖温度场试验研究[J].车用发动机,2009(2):36-38.

[5]李春玲.柴油机气缸盖温度场数值模拟[J].柴油机设计与制造,2006(2):298-300.

[6]郭立新.某汽油机气缸盖热负荷分析[J].现代车用动力,2009(4):16-20.

[7]杜建红.内燃机气缸盖瞬态温度场数值模拟[J].华北工学院测试技术学报,1999(4):203-206.

[8]傅衣铭.材料力学[M].长沙:湖南大学出版社,2007.