柴油机喷油器针阀密封锥面磨损试验研究

Experimental Study on Wear of Sealing Cone Surface of Needle Valve for Diesel Engines

针阀偶件是柴油机燃油供给系统的三大精密偶件之一,在工作过程中针阀偶件的密封锥面容易因磨损而失效。对柴油机喷油器针阀偶件密封锥面的磨损性能进行理论分析,分析表明,密封锥面的磨损主要是由针阀落座的冲击力与柴油中夹带杂质的综合作用所造成的,密封锥面磨损后会变形,导致表面粗糙度增大,密封效果变差。通过发动机台架实验对喷油器进行试验研究,利用扫描电镜分析针阀偶件密封锥面磨损形貌,并分析其磨损机制。实验结果表明,随着使用时间的增长,针阀的表面存在明显磨损现象,进而出现清晰的划痕和大面积的剥落,密封性能丧失;针阀磨损初期以磨粒磨损为主,导致表面产生划痕,后期主要是黏着磨损,材料大面积剥落。

The injector needle valve couples is one of the three big precision couplings of diesel fuel injection system, and its sealing cone surface is prone to become invalid because of wear and tear during the working process.Theoretic analysis of the wear performance of the seal cone surface was carried out. It is shown that the wear of sealing cone surface is mainly caused by comprehensive function of the impact of the needle valve seat and impurity in the diesel oil.The sealing cone surface is deformed after wear, which causes the increasing of surface roughness and the lowering of sealing effects. The experimental study of the injector was carried out in the test bench of engine, and the scanning electron microscopy （SEM） was used to analyze the worn morphology of sealing cone surface and its wear mechanism.The experimental result shows that along with the increasing of time usage ,there is obvious wear on the surface of needle valve, then clear scratches and a large area of spalling appear on the surface of needle valve to cause the failure of the sealing surface.Particle abrasive wear appears mainly in the early wear phase of needle valve, which produces scratches in the surface, and adhesive wear and a large area of spalling appear in later period.