柴油机气缸盖漏气故障分析与优化

袁贝贝^1，2，高磊^1，2，路海龙^1，2，田丰^1，2，张忠元^1，2，张乐天^1，2

1.内燃机与动力系统全国重点实验室，山东 潍坊  261061；2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：为解决某型柴油机气缸盖出现的批量漏气故障，从气缸盖垫片材料、气缸盖材料及结构、缸盖螺栓拧紧工艺、气缸盖垫片面压、人为因素等方面进行分析，确定气缸盖漏气原因为气缸盖和气缸盖垫片接触位置的凸台结构设计不合理，且垫片材料硬度较低导致气缸盖垫片产生塑性变形。采用取消气缸盖凸台、更换气缸盖垫片材质和提高气缸盖螺栓轴力3种改进措施，并进行仿真计算和试验对比。结果表明：气缸盖材料采用HT300灰铸铁，气缸盖结构加强，缸盖螺栓轴力由200 kN增大为230 kN后，将缸盖底面由凸台结构改为平面结构，或将垫片材料由碳钢改为不锈钢，均可有效降低气缸盖漏气风险；两种优化方案均通过全速全负荷耐久试验和热冲击试验验证，市场应用反馈采用优化方案后，气缸盖均未再发生漏气故障。

关键词：柴油机；气缸盖垫片；漏气；螺栓轴力；密封性耐久试验

Fault analysis of cylinder head air leakage in diesel engines and its optimization

YUAN Beibei^1,2, GAO Lei^1,2, LU Hailong^1,2, TIAN Feng^1,2, ZHANG Zhongyuan^1,2, ZHANG Letian^1,2

1.State Key Laboratory of Engine and Powertrain System, Weifang 261061, China; 2.Weichai Power Co., Ltd., Weifang 261061, China

Abstract: To address the batch air leakage failure of cylinder head gaskets in a certain type of diesel engine, comprehensive analysis is conducted from multiple aspects, including cylinder head gasket material, cylinder head material and structure, cylinder head bolt tightening process, surface pressure of the gasket, and human factors. It is determined that the unreasonable design of the boss structure at the contact interface between the cylinder head and the gasket, together with the low hardness of the gasket material, leads to plastic deformation of the gasket, which is the primary cause of air leakage. Three improvement measures are proposed, namely canceling the boss structure on the cylinder head, replacing the gasket material, and increasing the axial force of cylinder head bolts. Corresponding simulation calculations and comparative tests are carried out. The results show that after adopting HT300 gray cast iron for the cylinder head, strengthening the cylinder head structure, increasing the bolt axial force from 200 kN to 230 kN, changing the boss structure of the cylinder head bottom to a flat structure, or replacing the carbon steel gasket with stainless steel material, the air leakage risk can be significantly reduced. Both optimization schemes have passed the full-speed full-load durability test and thermal shock test. Market application feedback verifies that no air leakage failure has occurred on cylinder head gaskets after optimization.

Keywords: diesel engine; cylinder head gasket; air leakage; bolt axial force; tightness durability test