Structure Design And Characteristic Analysis Of High Pressure Common Rail Injector Based On Giant Magnetostrictive Actuator

Energy saving and environmental protection are two major themes facing the world today.With the increasingly serious energy crisis and people's attention to environmental pollution,higher requirements are put forward for the energy saving and emission technologies of diesel engines at home and abroad.Under the influence of energy conservation and emission reduction,the research on high-pressure common rail electronically controlled fuel injector becomes very important.The traditional high-pressure common rail electronically controlled injector is more and more difficult to meet people's requirements for energy conservation and environmental protection.It is urgent to develop a high-pressure common rail electronically controlled injector with high response speed,high stability and high injection accuracy,which can not only improve the research and development technology level of high-pressure common rail electronic injector in China,but also promote the implementation of "made in China 2025" strategy.There are some problems in electromagnetic and piezoelectric injector,such as slow response,poor stability and low injection accuracy.In this paper,giant magnetostrictive material(GMM)is used to design a kind of direct drive high-pressure common rail electronic injector.The injector directly drives the needle valve through a giant magnetostrictive actuator(GMA),not only can quickly control the opening and closing of needle valve,but also can accurately control the specific position of needle valve.The main work of this paper is as follows(1)Based on the magnetostrictive effect of giant magnetostrictive material and the precise transmission theory of flexure hinge,the giant magnetostrictive driver and flexure reversing amplifying mechanism are designed,a structure scheme of direct drive high pressure common rail electronic controlled injector is proposed,the working principle of injector is introduced,and the structure of GMA is designed,including the design and material selection of giant magnetostrictive rod,magnetic field design According to the type and characteristics of flexure hinge micro displacement amplification mechanism,the structure of flexure reversing amplification mechanism is designed.Finally,the structure of needle valve body is designed.Through the design of each part of the structure,the optimal structure of the injector is determined to meet the driving requirements of the injector needle valve.(2)According to the designed mechanism and the theory of elasticity,the static and dynamic models of the mechanism are established on the basis of considering the offset of the rotating center of the flexure hinge.The expressions of the amplification ratio and the natural frequency of the mechanism are derived,and the influence of the structural parameters of the flexure hinge on the static and dynamic characteristics of the mechanism is obtained,In order to obtain the optimal value of the structural parameters of the flexure hinge,the optimization objective function is established,and the MATLAB software is used to optimize the design.The ANSYS Workbench finite element software is used to simulate and analyze the optimized structure,and the correctness of the static and dynamic model is verified,from which the transmission characteristics of the flexure reversing amplification mechanism are obtained.(3)The dynamic modeling and simulation analysis of Giant magnetostrictive high pressure common rail injector are carried out,including the nonlinear dynamic modeling of GMA and the dynamic modeling of needle valve mechanism.The transfer functions of GMA and needle valve mechanism are derived,and the dynamic characteristics of GMA and needle valve mechanism are simulated and analyzed with MATLAB software,and the structure of injector is obtained The relationship between the parameters and the dynamic response performance is conducive to the optimization of the parameters and provides a theoretical basis for further improving the response speed and stability of the injector.(4)The multi-field coupling characteristics of giant magnetostrictive injector are analyzed.The multi-physical field of giant magnetostrictive injector is mainly composed of three parts.The first part is the electric magnetic thermal coupling field.Firstly,the GMA electromagnetic field model is established.Through the steady-state and transient analysis of the electromagnetic field,the influence of driving coil current,coil turns,bias current,preloading stress,magnetization period,driving frequency and other factors on GMM models is obtained.Secondly,the temperature field of GMA is simulated and analyzed by COMSOL multiphysics software.The temperature rise characteristics of the material and the effect of water cooling on the temperature distribution of GMA rod are obtained.The second part is the electro magnetic mechanical coupling field.The electro magnetic mechanical coupling simulation model of the injector is established by using the software of COMSOL multiphysics,and the curves of needle valve displacement and driver output displacement with current are obtained.The third part is the internal flow field of the nozzle.The mathematical model of gas-liquid two-phase flow in the nozzle is established,and the simulation analysis of gas-liquid two-phase flow in the nozzle is carried out by using FLUENT software.The influence of the needle valve lift,injection pressure and outlet back pressure on the internal flow characteristics of the nozzle is obtained.Through the analysis of the multi-field coupling characteristics of the giant magnetostrictive injector,The influence of the parameters in each physical field on the fuel injection performance of the injector is mastered,which is conducive to further improving the injection accuracy.Fig[97]table[7]reference[84]...