Design Of Key Structure Paremeters Of High Pressure Common Rail Injector

With the global attention to the problem of environmental pollution,automobile emission regulations becomes more and more strict in China.The traditional diesel injection system is difficult to deal with stringent emission regulations.Electronic control technology open a new space to solve this problem.The paper depend on ASIMCO Tianwei YN19 type engine common rail system project.The research target is injector the key part of common rail system,Based on theoretic calculation,experiment operation and simulation analysis to design the CR parts structures and parameters and analysis injector functions.Simulate the relationship between parts structure and injector function.Through this platform promote electronically controlled injector platform upgrade from 160 MPa to 180 MPa work pressure.The design of key structure parameters design and performance of the injector are studied.Accumulate experience and methods for our self development of higher pressure CR injector.Firstly,this paper has simplified the injectors,and according to the structure and working principle of the injector,established the corresponding mathematical and physical model.The paper has applied the software AMESim to establish the simulation model of injector working process,and compared the fuel injection rate results with the same condition test results.It show that the simulation calculation results and the real situation are more consistent,the model can be applied in the simulation study of high-pressure common rail fuel injector response characteristics.Secondly,based on the established numerical bench,it used the injector model system studied injection pressure,control chamber volume,inlet orifice diameter,outlet orifice diameter,outlet diffusion hole and other structure parameters effects on the response characteristics of injector,and summarizes the influences of the various parameters to find the selected range of the optimal value.The main research results are as follows:(1)The opening and closing response speed increase with the fuel supply pressure;(2)The volume of the control chamber has a great influence on building-up of pressure of the control chamber.In a certain range,when the volume is small,the system response rapidly.Withthe volume of the increase,the system response speed becomes relatively slow.Volume is too large or too small of the system have adverse effects;(3)Increased control valve inlet orifice diameter,is conducive to improve the valve closing speed,but decreased the needle valve opening speed;(4)Increased the outlet orifice diameter,injector's opening response rapidly,and closing speed is basically unchanged.Appropriate increase of the outlet orifice diameter can help to improve the response characteristics and fuel injection characteristics of the injector.;(5)The needle valve closing time,injection duration and injection quantity increase with the outlet diffusion hole diameter.Finally,this paper based on the obtained results,comparing with injector performance after upgrading,optimization scheme comparison,performance prediction,sensitivity analysis,auxiliary 180 MPa injector scheme optimization and upgrading to meet the performance requirements of the engine.Determine the matching results and tolerance range of the common rail injector upgrade: the inlet orifice flow:0.24±5% L/min;the outlet orifice flow:0.2967±5% L/min;the outlet diffusion hole diameter:0.4mm ±0.01 mm.