| The in-line plunger fuel injection pump has the advantages of compact structure,light weight,and controllable fuel injection volume,and has been widely used in the fuel supply system of diesel engines.At present,domestically produced in-line fuel injection pumps generally use the plunger assembly as the fuel supply element,but the plunger assembly stuck frequently in the operation of a certain type of fuel injection pump,which poses a direct threat to the personal and property safety of users.However,most of the existing research on the plunger assembly focuses on the axial type and high pressure common rail fuel injection pump,while the research on the in-line type and its reliability is relatively rare.In view of this,this thesis takes the plunger assembly of the in-line fuel injection pump as the research object,and conducts an in-depth study on the failure of the plunger assembly.The thesis content and results are mainly divided into the following parts:(1)Structural analysis and modeling of the plunger assembly.A detailed analysis is conducted on the functions and structural characteristics of the fuel injection pump,fuel supply components,and the plunger assembly.Based on the disassembly and inspection results,the key area near the plunger head is identified,and it is determined that the unreasonable fit clearance of the plunger assembly is an important cause of stuck.In addition,the geometric model of the plunger assembly is constructed by the Solid Works.According to the working principle,the key moment is found out through the Motion.At this time,the position relationship of the plunger assembly laid the model foundation for subsequent research.(2)Structural finite element analysis and improvement of plunger assembly.Converting the geometric model of the plunger assembly into a finite element model.The finite element model is simplified by using pressure instead of tightening torque when the boundary conditions are set.The structural statics simulation of the plunger assembly is carried out by ANSYS Workbench.In the results,the head of plunger assembly expanded and the corresponding position of the plunger sleeve contracted under the working condition.It leads to the reduction of the fitting clearance of the plunger assembly exceeding the designed clearance,thus causing the stuck fault.In addition,two improvement measures for structural deformation of the plunger assembly are proposed and verified by simulation.(3)Reliability analysis of anti-stuck of the plunger assembly.Due to the uncertainty of load,size and other parameters of the plunger assembly in actual engineering,and the probability reliability accuracy is low in the case of insufficient data information.In view of this,this thesis uses interval analysis to model the non-probabilistic reliability of the plunger assembly,deduces and calculates the variation of its non-probabilistic reliability index with the design clearance.In addition,this thesis uses two different sensitivity analysis methods to analyze the global sensitivity of the reliability index.The results show that the parameters which mainly affect the non-probabilistic reliability index are knifeedge width,hole length,aperture,tightening torque,and oil supply pressure.At the same time,the importance of the parameters is sorted.The results of sensitivity analysis indicate the direction for subsequent improvement of the model parameters and provide reasonable guidance for the design of the main parameters of the plunger assembly. |
