李加旺，张志福，田身军，李德银

奇瑞汽车股份有限公司，安徽 芜湖 241009

摘要：为解决某压缩天然气(compressed natural gas, CNG)发动机排气门-座圈异常磨损失效的问题，通过分析座圈磨损机理，确定座圈材料的屈服强度、座圈表面接触应力、有效表面膜和表面温度为影响CNG发动机排气门-座圈磨损特征的关键因素。提出优化座圈材料、降低座圈表面法向载荷的接触应力、降低排气门-座圈摩擦副的表面温度及保证座圈有效表面膜的生成等优化方案。对优化方案进行台架和整车试验验证，结果表明优化后座圈最大磨损量由0.288 mm降到0.078 mm，满足设计要求，改进效果明显，市场反馈表现良好，没有出现因座圈异常磨损导致的发动机缸压不足、抖动等故障。

关键词：CNG发动机；座圈；黏着磨损；台架验证

Abstract：In order to solve the problem of wear failure of the exhaust valve seat ring in a CNG engine, the wear mechanism of the seat ring is analysed. It is determined that the yield strength of the seat ring material, the contact stress of the seat ring surface, the surface temperature and the effective surface facial mask are the key factors affecting the wear characteristics of the exhaust valve seat ring. The optimization such as improving the seat ring material, reducing the contact stress of the normal load on the seat ring surface, reducing the surface temperature of the exhaust valve seat ring friction pair and ensuring the formation of the effective surface facial mask of the seat ring are tested. The bench and vehicle tests are carried out to verify the optimization schemes. The results show that the maximum wear of the optimized rear seat ring is reduced from 0.288 mm to 0.078 mm, which meets the design requirements. The improvement effect is obvious, the market feedback is good, and there are no failures such as insufficient cylinder pressure and shaking of the engine caused by abnormal wear of the seat ring.

Keywords:CNG engine; valve seat; adhesive wear；bench verification