低速重载工况下连杆小头轴承变形与润滑耦合分析

连杆小头轴承是内燃机中的关键摩擦副,在低速重载工况下容易发生变形和咬合失效,是影响重型卡车发动机可靠性的重要原因。为揭示低速重载工况下连杆小头轴承的性能,以某6缸柴油机连杆小头轴承为分析对象,考虑连杆小头轴承和活塞销孔轴承对活塞销的摩擦转矩,建立柴油机活塞-连杆-曲轴摩擦动力学模型,在此基础上耦合连杆小头轴承的瞬时弹性变形,对比分析轴承变形对连杆小头轴承润滑性能的影响。研究结果表明：在低速重载工况下,忽略轴承变形可能会使预测的活塞销旋转方向相反;连杆小头轴承在吸气冲程受拉会产生严重变形,并且导致轴承与活塞销间润滑性能下降。

Coupling Analysis of Deformation and Lubrication of Connecting Rod Small End Bearing under Low Speed and Heavy Load Conditions

Connecting rod small end bearing is the key friction pair in internal combustion engines.It is prone to deformation and seizure failure under low speed and heavy load conditions,which is an important reason affecting the reliability of heavy-duty truck engines.To reveal the performance of connecting rod small end bearings under low speed and heavy load conditions,the tribological dynamic model of piston-connecting rod-crankshaft was established to analyze the connecting rod small end bearing of a 6-cylinder diesel engine.The torque of the connecting rod small end bearing and the piston pin hole bearing on the piston pin was considered in the model.Then the transient elastic deformation of the small end bearing was coupled into the model,and the influence of bearing deformation on the tribological performance prediction results was analyzed.The results show that under the low speed and heavy load conditions,ignoring the bearing deformation may make the predicted rotation direction of the piston pin opposite.During the suction stroke,the small end bearing is severely deformed and resulting in lubrication deterioration between the bearing and the piston pin.