机车柴油机喷油泵凸轮接触应力分析

针对机车柴油机喷油泵凸轮表面常出现点蚀、麻点、剥落等损伤问题,开展喷油泵凸轮轮廓升程段的接触应力研究,分析导致喷油泵凸轮表面失效的原因。以16V240ZJB型柴油机为例,通过对油泵凸轮轮廓曲线进行几何分析,导出凸轮升程段的运动方程。采用弹性力学中的赫兹理论,建立油泵凸轮接触应力的计算式,并通过计算机编程,从理论上计算和分析喷油泵凸轮表面的接触应力。理论计算结果表明:喷油泵凸轮的接触应力虽高达1 421.655 MPa,但并未超过许用应力值。因此建议从材料加工工艺方面查找原因,提高凸轮表面加工质量,并采用复合强化工艺,进一步加大喷油泵凸轮表面的强度。

Contact Stress Analysis on the Fuel Injection Pump Cam of Locomotive Diesel Engine

According to the injury problems frequently occurred on the surface of fuel injection pump cam of locomotive diesel engine,such as pitting,and spalling etc.,researches have been carried through on the contact stress of the profile lift section of pump cam.Causes resulting in the failure of cam surface are analyzed.Taking 16V240ZJB diesel engine as an example,the motion equation of cam lift section is deduced through geometry analysis on the profile curve of pump cam.The computation expression for the contact stress of pump cam is established by using Hertz theory of elasticity.By computer programming,the contact stress of pump cam surface is theoretically calculated and analyzed.Theoretical computation results indicate that although the contact stress of fuel injection pump cam is as high as 1 421.655 MPa,it does not exceed the allowable stress values.Therefore,it is recommended that causes should be investigated in terms of materials processing technology to improve the processing quality for the surface of pump cam.Composite strengthening technology is adopted to further increase the surface intensity of fuel injection pump cam.