Study On Leakage And Sealing Characteristics Of Precision Coupler Of High Pressure Common Rail Injector

The electronically controlled injector is the most central component of the high-pressure common rail fuel system,and the precision coupler is the most critical component of the injector.With the implementation of stricter emission regulations,the requirements for fuel injection pressure are constantly increasing,and the fuel leakage of precision parts will affect the injection pressure and performance of the injector.This paper mainly studies the fuel leakage law of the precision coupler of the high-pressure common rail injector.Through the study of the influence law of the leakage,it provides a reference for the injector seal,reduces the injection pressure loss and improves the fuel injection performance.This paper mainly studies from the following aspects.First of all,based on the structure and working principle of a certain type of injector,the system simulation model of the injector is established by using one-dimensional hydraulic simulation tool.The leakage module is used to simulate the leakage of the injector’s precision coupler and verified on the test bench.The accuracy of the simulation model.The effects of system parameters including oil supply pressure,fuel viscosity and coupling structural parameters including couple contact length,coupler diameter,gap film thickness and couple eccentricity on fuel leakage rate were studied.Fuel pressure and fuel injection were also studied.The influence of the pulse width and the structural parameters of the injector on the fuel injection performance of the injector;the results show that as the coupling of the direct and the gap oil film increases,the fuel leakage rate of the coupling increases,and the contact length of the coupling increases the fuel.The leak rate is reduced.Secondly,the three-dimensional model of the oil film of the injector’s precision coupler is established.The simulation model is structured and mesh-independent.The accuracy of the simulation model is verified by theoretical analysis.The effects of the diameter of the coupler,the contact length of the coupler and the thickness of the oil film on the flow velocity and pressure of the oil film and the rate of fuel leakage during the writing of the fuel were studied.The oil film model of the control valve was established and the film was applied by UDF.The dynamic pressure is applied at both ends to analyze the flow characteristics of the even oil film under the action of dynamic pressure,and the influence of different seal sealing structures on the fuel leakage rate is studied.The research results show that the annular groove is opened on the coupler and the interest rate is reduced.Finally,the finite element analysis of the needle valve body of the injector and the fluid-solid coupling analysis of the plunger plunger sleeve are carried out.The finite element analysis of the needle valve and the needle valve body in the Workbench is carried out to study the needle valve under the static load.The shape variable and equivalent stress of the needle valve body;the finite element analysis of the needle valve seat is carried out to study the effects of different needle seat materials,different temperatures and loads on the deformation and stress of the needle seat;The unidirectional fluid-solid coupling analysis is used to study the effect of oil film pressure on the deformation of the plunger couple.The results show that the oil film pressure will increase the radial deformation of the plunger coupler,thereby increasing the thickness of the gap oil film and increasing the plunger.The fuel leakage rate of the even piece of oil film.The research in this paper mainly obtains the influence of the structural parameters of a certain type of injector couple on the leakage of precision couple parts and the influence of the flow characteristics of the gap oil film.The research shows that the fuel leakage can be reduced by changing the structure of the coupler;The influence law of the finite element analysis of the valve coupler and the influence of the fluid-solid coupling of the plunger coupler can provide reference for the design of the injector’s precision coupler structure.