内燃机排气凸轮-滚轮副异常工况下热弹流润滑分析

Analysis on Thermo-Elastohydrodynamic Lubrication for Exhaust Cam-Roller Pair in Internal Combustion Engine under Abnormal Conditions

以某型号内燃机排气凸轮-滚子副为研究对象,建立有限长线接触条件下瞬态热弹流润滑数学模型及完全数值求解方法。依据实际载荷谱等工作参数下,给出凸轮-滚子间的滑动模型,获得凸轮-滚子副在凸轮旋转周期内润滑特性,并分析凸轮与滚子之间的打滑、滚轮偏斜和滚轮凸度对接触副润滑的影响。结果表明:打滑导致接触区温度和摩擦因数明显升高,从而弱化接触区润滑状态;滚子偏斜时油膜厚度明显减小,增加润滑失效的可能性。研究表明,在设计滚子凸度时考虑滚子偏斜问题的影响,可以在一定程度上缓解其负面影响。研究结果为凸轮-滚子副的润滑设计提供了一定的理论依据。

Based on the cam-roller pair of an internal combustion engine,a mathematical model of transient thermal elastohydrodynamic lubrication under finite line-contact and the corresponding full numerical solver were established.Under an actual load spectrum and other working parameters,the detailed lubrication performance of the cam-roller pair was obtained in a cam rotation cycle.The influences of the sliding between cam and roller and the roller tilting on the contact pair lubrication were analyzed.The results show that the cam-roller sliding results in noticeable increase in temperature and friction coefficient,which can deteriorate the contact zone lubrication.The roller tilting can worsen the lubrication of the contact zone,and increase the possibility of lubrication failure.Research is shown that considering the tilting of rollers when designing roller convexity can alleviate its negative impact to a certain extent.The results provide some theoretical data basis for the lubrication design of cam-roller pairs.