发动机燃油共轨螺纹烂牙失效分析及改进

Failure Analysis and Improvement of Engine Fuel Common Rail Thread of Rotten Teeth

在上海大众动力总成有限公司EA211系列发动机C6排放改造项目中,进行第二阶段国产化试制时,在拧紧燃油压力传感器时发生平均高达13.1%的燃油共轨螺纹烂牙现象。通过对造成断裂现象的原因进行排查,发现除1例为人为装配错位外,其余均为共轨端螺纹断裂导致螺纹烂牙,比例高达87.5%。组建QC小组针对该失效进行头脑风暴及系统图分析,对所有可能产生失效的原因进行一一排查,确定主要原因为(1)拧紧扭矩逼近燃油共轨螺纹承载上限;(2)拧紧枪转速设置过高。最终通过对扭矩参数的修正,并设计试验验证最终拧紧效果,消除了燃油共轨螺纹烂牙的风险。

In the EA211 series engine C6 emissionsrenovation project of Shanghai Volkswagen Powertrain Co.,Ltd.,during the second phase of localization trial production,an average of 13.1%of the fuel common rail thread rotten phenomenon occurred when the fuel pressure sensor was tightened.By investigating the cause of the fracture,one case was man-made assembly misalignment,and the rest were caused by thread rot at the common rail end,the proportion was as high as 87.5%.A QC team was organized for the failure,with the methods of brainstorming and chart analysis,some main reasons for cancellation were determined:(1)the tightening torque was approaching the upper limit of the fuel common rail thread load;(2)the tightening gun speed was set too high.Finally,the torque parameters were modified and the final tightening effect was verified by experiments,the risk of rotten teeth of the fuel common rail thread is eliminated.