发动机连杆小头轴承弹性流体动力润滑分析

Elastohydrodynamic Lubrication Analysis of Rod Small-end Bearing of Engine

分析某型发动机连杆小头衬套发黑变色的原因,指出高温是衬套发黑变色的主要原因,且高温是由于连杆和活塞销摩擦引起的。为研究连杆小头轴承的润滑情况,建立活塞销、连杆和活塞的有限元模型,并对其进行自由度缩减;建立连杆小头轴承EHD仿真分析模型,对连杆小头轴承油膜压力、粗糙接触压力、油膜厚度和润滑油泄油量等润滑特性参数进行分析。结果表明,润滑油流动不畅是导致衬套发黑变色的主要原因。提出了匹配连杆小头孔型线和调整活塞销刚度的综合改进措施,结果表明:采用匹配孔型线的连杆小头衬套及增加活塞销刚度均可降低最大粗糙接触压力,改善润滑。

The black substance on the connecting rod small-end was analyzed.It is found that the black substance is produced by high temperature,and the high temperature is caused by friction between connecting rod small-end,piston and piston pin.In order to study the lubrication of the connecting rod small-end,the finite element model of piston,piston pin and connecting rod small-end were established,and the degree of freedom is reduced.EHD model of connecting rod small-end was built to study oil film pressure and thickness,asperity contact pressure and oil flow.It is found that the poor flow of lubricating oil is the main cause of the blackening and discoloration of bushing.The comprehensive improvement measures for matching the hole contouring of rod small-end and and adjusting the stiffness of the piston pin were put forward.The results show that the maximum rough contact pressure can be reduced and the lubrication can be improved by using the rod small-end bush after matching hole contouring and increasing the stiffness of piston pin.