Lubrication Characteristics and Impact Effects of Connecting Rod Small-End Frictional Pair under Cavitation Effect
In order to improve the lubrication and piston pin impact characteristics of connecting rod small-end bearing,a multi-body dynamic model of mixed lubrication piston and connecting rod group was built by AVL EXCITE Power Unit soft-ware with a high-pressure common rail four-cylinder diesel engine as the research object based on the rough peak contact theo-ry,average flow model and elastohydrodynamic lubrication theory.The influence of cavitation effect on the lubrication and im-pact characteristics of connecting rod small end frictional pair at different speeds was studied.The results show that the peak oil film pressure reaches the maximum value of 197.1 Mpa and the minimum oil film thickness reaches the minimum value of 1.8μm after 1080°at the rated power speed of 2400 r/min,while the lubricating oil filling rate is lower than 0.12 during the whole engine cycle.Under the idle speed of 800 r/min,the maximum torque speed of 1600 r/min,and the rated power speed of 2400 r/min,the cavitation area first transfers from the lower half of the connecting rod small-end bearing to the upper half, and then back to the lower half during the four strokes of intake,compression,work,and exhaust.The increase of the speed will lead to the increase of peak oil film pressure,the decrease of minimum oil film thickness,the increase of rough contact pressure,the increase of Z-direction velocity peak for piston pin,and the increase of impact on the small-end bearing of con-necting rod.The average filling rates of lubricating oil at 800 r/min,1600 r/min and 2400 r/min are 0.84,0.70 and 0.69 re-spectively,and the aggravation of cavitation becomes true because the filling rate of lubricating oil decreases with the increase of speed.
cavitation effectconnecting rod small endlubrication characteristicimpact characteristic
万方数据
维普
