摘要
针对某重型柴油机配气机构耐久试验后出现挺柱底面磨损及剥落的现象,分别采用金相分析、硬度分析等方法对挺柱进行物化分析,并利用正时阀系统动力学分析软件AVL Excite Timing Drive仿真计算凸轮与挺柱的接触应力。结果表明:挺柱材料及硬度符合设计要求,凸轮-挺柱接触应力过大是造成挺柱失效的主要原因。为最大限度保证挺柱底面与凸轮全宽接触,将挺柱底面直径由30.5 mm增大至36.8 mm。仿真计算和试验表明:进气凸轮与挺柱底面的接触应力由974.7 MPa降为706.0 MPa,排气凸轮与挺柱底面的接触应力由929.8 MPa降为745.0 MPa。对优化后的挺柱进行耐久试验,挺柱底面未出现不正常磨损及剥落现象,说明增大挺柱底面直径可以降低凸轮-挺柱的磨损。
In view of the phenomenon of wear and fatigue flaking on the bottom surface of the tappet after the durability test of valve timing system of a heavy-duty diesel engine,the physical and chemical analysis of the tappet are carried out by means of metallographic analysis and hardness analysis,and the contact stress between cam and tappet is simulated by software AVL Excite Timing Drive.The results shows that the material and hardness of tappet meet the design requirements,and the main reason of tappet failure is the excessive contact stress between cam and tappet.In order to maximize the full width contact between the bottom surface of the tappet and the cam,the bottom diameter of the tappet is increased from 30.5 mm to 36.8 mm.Simulation calculation and experimental verification shows that the contact stress between the intake cam and the bottom surface of the tappet decreases from 974.7 MPa to 706.0 MPa,and that between the exhaust cam and the bottom surface of the tappet decreases from 929.8 MPa to 745.0 MPa.Abnormal wear and fatigue flaking on the bottom surface of the tappet is not appear after the durability test of the optimized tappet,which indicates that increasing the bottom diameter of the tappet can reduce the wear between cam and tappet.
作者
王刚
崔凯
陈广茂
WANG Gang;CUI Kai;CHEN Guangmao(State Key Laboratory of Engine Reliability, Weifang 261061, China;Weichai Power Co., Ltd., Weifang 261061, China)
出处
《山东交通学院学报》
CAS
2021年第4期14-20,共7页
Journal of Shandong Jiaotong University
关键词
重型柴油机
凸轮
挺柱
接触应力
磨损
剥落
疲劳失效
heavy-duty diesel engine
cam
tappet
contact stress
wear
flaking
fatigue failure
