发动机排气管漏气失效分析与改进

王利平^1,2，张玉娟^1,2，李群力^1,2，张文霞^1,2

1.内燃机可靠性国家重点试验室，山东 潍坊  261061；2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：为解决某发动机在耐久试验过程中出现的排气管严重漏气问题，分析排气管材料、螺栓力矩、排气管与增压器和气缸盖结合法兰平面度，结合排气管、气缸盖、垫片的面压试验结果，确认排气管漏气原因，并对排气管结构进行针对性优化，对优化后的排气管进行面压试验和台架试验验证。结果表明：排气管垫片密封带不均匀、不连续，部分位置面压较小，排气管法兰面平面度不满足要求，法兰面加工后严重变形是排气管漏气的主要原因；结合仿真计算的排气管垫片密封性能，在排气管漏气位置增加加强筋、增大排气管法兰面厚度，解决了排气管漏气故障。

关键词：排气管；漏气；失效分析；平面度；面压

Failure analysis of engine exhaust pipe leakage and its improvement

WANG Liping^1,2, ZHANG Yujuan^1,2, LI Qunli^1,2, ZHANG Wenxia^1,2

1.State Key Laboratory of Engine Reliability, Weifang 261061, China;

2. Weichai Power Co., Ltd., Weifang 261061, China

Abstract: In order to solve the problem of air leakage in exhaust pipe of an engine during the durability test, an analysis of the exhaust pipe material, bolt torque, flange face flatness of the exhaust pipe in conjunction with the turbocharger and cylinder head is conducted. Surface pressure tests of the exhaust pipe, cylinder head, and gaskets are carried out to identify the cause of the exhaust pipe air leakage. A targeted optimization of the exhaust pipe structure is performed, and the optimized exhaust pipe is validated through surface pressure tests and bench testing. The results show that the exhaust pipe gasket sealing strip is uneven and discontinuous, with lower surface pressure at some positions. The flange face flatness of the exhaust pipe does not meet requirements, and severe deformation after flange face processing is the main cause of the exhaust pipe air leakage. By combining the simulation calculation of the exhaust pipe gasket sealing performance, adding reinforcement ribs to the exhaust pipe and increasing the thickness of the exhaust pipe flange face, the problem of exhaust pipe air leakage has been resolved.

Keywords: exhaust pipe;  air leakage;failure analysis; flange face; surface pressure