某汽油发动机连杆对NVH性能的影响分析及优化

Analysis and Optimization of the Effects of Connecting Rod on NVH Performance in a Gasoline Engine

某汽油发动机在进行台架热磨合试验时,怠速工况出现敲击噪声异响,此敲击现象出现在特定频率段内。经NVH测试数据分析,当发动机排气行程结束至进气行程开启时,活塞销与连杆小头之间产生较大敲击能。通过改善连杆小头处润滑方式,减小连杆衬套磨损,从而减小活塞销与连杆小头之间间隙。改善后,样件通过了NVH测试试验,解决了发动机怠速工况敲击异响问题。

During the thermal running-in test of a gasoline engine, the knock noise appeared under the idle condition, and this knock phenomenon appeared in a specific frequency range. According to the analysis of NVH test data, the abnormal sound was caused by the large striking energy between the piston pin and the small head of the connecting rod, when the engine was operating during the period from the end of exhaust stroke to the start of intake stroke. By improving the lubrication mode of connecting rod small head, the wear of connecting rod bushing was reduced, and the gap between piston pin and connecting rod small head was reduced. The improved sample passed the NVH test and the problem of abnormal knock noise in idle condition was solved.