Study On Suppression Of Piezo Injector Hysteresis

High pressure common rail fuel injection system is the core technology of diesel engine.As the most important and complicated component of high pressure common rail fuel injection system,Piezo injector receives more and more attention from the domestic automotive industry researchers.Piezo Actuactor is the core component of the Piezo injector,and its hysteresis characteristic will cause 2～10%of output displacement error generated by the injector needle valve.If the relationship between its input voltage and its output displacement is regarded as a simple linear relationship,the volume and rate of fuel injection of the Piezo injector will be affected to a certain extent.At present,a lot of researches focus on the control of Piezo injector,but there are few researches on the control mode of restraining the hysteresis of Piezo injector.Therefore,it is of great realistic significance to design a control mode that can restrain the hysteresis of the Piezo injector.Firstly,in this thesis,the Duhem model is chosen as the hysteresis model of Piezo injector actuators.Secondly,the hysteresis model of Piezo actuator is modeled based on Duhem model,and the recursive least squares(RLS)and the least square method with restricted memory are used respectively to identify the paraleters of the model.Thirdly,according to the voltage input requirenent of the established Duhem model,based on the driving principle of the Piezo actuator,the circuit of each module is designed.Finally,according to the Duhem hysteretic model established,the hysteretic inverse lodel of Piezo actuator is obtained.Combined with the mechanical characteristics ot Piezo injector,an open loop feed-forward control mode is adopted to suppress the hysteresis of Piezo injector.The experimental results show that,the injector control method that suppresses the hysteresis of Piezo actuator designed in this thesis is fully consistent with the control requirements of Piezo injector.A fter installing the designed control method of suppressing the hysteresis of Piezo injector on the fuel injector test platform,it is found in the analysis of the test data that,the time for opening the needle valve of the injector is quicker and the time for closing is slowed down,verifying the feasibility of control mode of suppressing the hysteresis of Piezo injector.