Study On The Effect Of Wear And Structure Of Injector Needle Valve On Sealing Performance Of High Pressure Common Rail System

As one of the most precise components of the common rail system,the working condition of the injector directly determines the working performance of the common rail system.During the operation of the injector,the needle valve constantly does high-speed reciprocating motion and impacts with the valve seat causing wear,resulting in the reduction of the sealing performance of the sealing surface of the injector needle valve coupling.Therefore,the study of the wear of the injector needle valve and the influence of structural parameters on the sealing performance of the needle valve can provide reference for the design and improvement of the injector.First,this paper describes the working principle of high-pressure common rail injector,introduces the mathematical model of injector,analyzes the typical wear mechanism,analyzes the possible wear of needle valve during the working process in combination with the working process of injector,further analyzes the wear problem,and builds the finite element unwear model and wear model of injector based on this.Then,using the constructed finite element model,the influence law of different needle valve wear conditions on the sealing performance of the injector needle valve is analyzed.The research results show that when the depth of the injector needle valve local wear is fixed,the smaller the wear width,the worse the injector sealing performance,and when the wear width reaches a certain value,the wear width has little effect on the sealing performance of the needle valve,the reason for this phenomenon is that as the local wear width increases,the contact stress between the wear area and the valve seat increases after the needle valve produces deformation,and when the wear width reaches a certain value,the When the wear width reaches a certain value,the contact stress in the wear area tends to stabilize,and the sealing performance also tends to stabilize;when the injector needle valve local wear width is certain,the sealing performance of the injector needle valve sealing surface decreases with the increasing wear depth,and when the wear depth reaches a certain value,the contact stress in the wear area is less than the sealing specific pressure required for sealing,resulting in the sealing failure of the injector needle valve sealing surface;when the overall wear of the injector occurs,the Needle valve sealing surface width increases with the increase in wear depth,the contact stress on the sealing surface decreases with the increase in wear depth,and when the wear depth exceeds a certain value,the contact stress will be for the sealing specific pressure required for sealing,resulting in the sealing failure of the injector needle valve sealing surface.Finally,the influence law of the needle valve structural parameters on the sealing performance of the injector needle valve sealing surface was studied.Using the unwear finite element model and simulations,the law of the influence of needle valve wear on the sealing performance obtained from the previous analysis is combined with the law of the influence of needle valve structural parameters on the sealing performance of the injector needle valve sealing surface,and the method of improving the performance of the needle valve sealing surface is proposed.The research results show that: the sealing performance of the needle valve sealing surface decreases with the increase of the needle valve cone angle angle and the diameter of the needle valve sealing ring,and vice versa,the sealing performance of the injector needle valve can be improved.Specifically,when the needle valve taper angle is 60°or when the needle valve seal ring diameter is 4.8mm,the sealing performance of the needle valve sealing surface of the injector is better than that of the unworn model,and the sealing performance of the injector is also better than that of the unworn model when the needle valve is under different wear conditions.