Study On Failure Factors Of Needle Valve Injector

For the research of the needle valve and the needle valve seat of the diesel engine injector,it is difficult to measure the stress value of the collision process through experimental means,and the traditional research is usually to use the stress calculation formula to calculate the impact stress of the needle valve and the needle valve seat,Even though the novel method of displaying dynamics is currently used to calculate the impact stress of the needle valve and the needle valve seat,only the impact stress of the needle valve and the needle valve seat in one impact process is analyzed and calculated,and the impact process is rarely performed.detailed analysis.Another part of the research is to use the experimental method to study the impact of the needle valve and the needle valve seat to obtain a picture of the wear scar of the needle valve and the needle valve seat after working for a period of time,or to estimate the depth of the wear scar.There is basically no analysis of the multiple impact processes and wear of the needle valve and the needle valve seat.Therefore,it is necessary to conduct a more in-depth and systematic analysis of the impact wear of the diesel engine needle valve assembly.Comparing various research methods,this paper uses the finite element analysis method combined with wear experiment analysis to study the impact wear of the needle valve assembly in the diesel engine injector.The main idea is to combine the finite element method with the experiment,and analyze the impact wear of the needle valve assembly.Taking the fuel injector provided by an enterprise as the research object,the following work is mainly done:(1)Research on the impact stability of the injector needle valve assemblyFirst,the first impact of the needle valve and the needle valve assembly is analyzed based on the finite element method,and the results of the first impact analysis are sorted out,and then the first impact law of the needle valve assembly and the accuracy of the finite element model are analyzed and judged According to the movement law of the needle valve assembly of the injector during the normal operation of the diesel engine,combined with the secondary development function of the finite element analysis software,the multiple impacts of the needle valve assembly are analyzed,and the law of the impact process is analyzed,Propose and improve the evaluation index of the steady state of the multiple impact of the needle valve assembly,and obtain the maximum contact stress after the impact is stable.(2)Experimental study on impact wear of needle valveSecondly,based on the maximum contact stress value after the impact is stabilized and the multiple impact processes,combined with the actual movement law of the needle valve assembly in the normal operation of the diesel engine,the main wear type of the needle valve assembly is analyzed and determined,and then the The needle valve assembly is subjected to wear experiment analysis to obtain the dynamic friction coefficient and wear amount of the wear experiment.The wear coefficient is calculated using the classic wear formula to obtain the wear volume and wear depth,and the impact wear life of the needle valve assembly is predicted.(3)Structural optimization design of needle valve coupleFinally,based on the orthogonal experiment design combined with the working principle of multiple injectors and the influence of various parameters,the structure of the needle valve assembly is optimized and analyzed.According to the technical specifications of the needle valve assembly and its selection for the diesel engine injector The injection rule has a small effect on the structural parameters and sets a reasonable level.According to the standardized orthogonal table,the needle valve assembly is randomly subjected to multiple impact analysis,combined with the wear law obtained by the impact wear experiment to determine the accuracy and reliability of the optimization experiment.Finally,the optimized structure is obtained,and the optimized needle valve assembly is again subjected to multiple verification experiments of impact stability analysis to obtain the maximum contact stress after stability,and the impact wear life is predicted according to its value;the final judgment is optimized Whether the impact wear life of the needle valve structure is greater than the design value of 6000 h,thereby improving the overall emission performance and fuel economy of the diesel engine by increasing the service life of the needle valve assembly.Through the analysis of the steady-state response of the impact of the needle valve assembly of the diesel engine and the experimental study of the wear,it is possible to understand the impact wear law in more detail,which is convenient to select the appropriate parameters in the design process,improve the working reliability of the injector and the fuel of the diesel Economical.And it can provide a more systematic idea for the optimal design of the diesel engine needle valve assembly.