Research On Injection Characteristics And Structural Optimization Of High Pressure Common Rail Electromagnetic Injector

Diesel engine has been widely used in the field of mechanical and power with high themal efficiency, large torque, the advantages of good economic performance. Due to the fuel combustion quality determines the economy of the engine, noise and emission and many other performance, so it is very important that giving an insight into the fuel injection process and precise control of fuel injection quantity to improve the quality of combustion in cylinder of engine. The application of high pressure common rail system in diesel engine is an effective measure to sovle the above problems, and the performance of fuel injcetion of the high pressure common rail electromagnetic injector is very important to the working characteristic of diesel engine. Therefore, this paper researched the injection charateristics of the high pressure common rail electromagnetic injector, and the optimization design was carried out on the key structural parameters of the injector.Firstly, the injector was simplified reasonabaly based on the real structure and working principle of high pressure common rail electromagnetic injector, the physical and mathematical model was build, and the one dimensional simulation model of electromagnetic cotrolled high pressure common rail injector was build by using the AMESim software. By comparing the test and simulation results, the accuracy of the one dimensional model was validated. Then, the influence of the common rail pressure, control of pulse widths, in and out hole diameters, nozzle hole diameter, needle lift and seat surface angle on the injection charactertics was carried out. The influence law of various parameters on the injection characteristics was summarized, and the best value range of each parameter was selected.Secondly, the internal flow characteristic of the nozzle was deeply studied by using the three dimensional simulation method. The influence law of the chamber diameter, seat surface angle, nozzle angle, oil rounded corners and needle lift on the nozzle internal flow characteristics was studied to provide reference for structural parameters optimization of fuel injector.Finally, combining the one and three dimensional simulation results, in order to improve the flow and injection characteristics of the fuel injector, the optimized test for maching of the key structural parameters was conduted by using orthogonal design. The optimization results show that when the inlet and outlet hole diameter of the control chamber is 0.27mm/0.29mm, nozzle hole diameter is 0.23mm, the needle lift is 0.55mm, the seat surface angle is 40°, the flow coefficient of the control chamber outlet hole is 0.85 and the flow coefficient of the nozzle hole is 0.85, the flow performance and injection characteristics of the fuel injector are the best. After optimization of the key structure parameters of the injector, both the flow and injection characteristics are all improved, the flow rate of the inlet hole increased 18.87% and flow rate of the outlet hole increased 16.76%, fuel injection rate increased 52.58%, eventually making the single injeciton quantity of the fuel injector increased 63.22%, and achieved the required level of the subject.