Research On Rail Pressure Control-oriented Observer Design And Characteristic Of Fuel Metering Valve

This paper expounds the structure and working principle of high pump,common rail,injector and other parts of common rail system.The research on how static leakage and dynamic leakage in injector affect the rail pressure in common rail is carried out.On the condition of simplifying and assumptions,this paper presents models of common rail system based on mathematical formula,and accuracy of the model is tested by experiments.The characteristic of high pump is analyzed by model simulation,and the factors that influence the efficience of high pump is concluded in this paper.On the basis of model built above,this paper builds observer model which aims to improve control strategy of rail pressure.The rail pressure signal obtained by observer model is more precise than the signal collected by pressure sensor.This paper also expounds the principle of first-order filter and kalman filter,and the advantage and disadvantage of these three different ways of signal filter is concluded through comparition of each other.Experiments on characteristic of flow control valve is carried out by using software and hardware bench.The relation between duty cycle and electric current,time delay of the valve before opening,workspace of the valve and the characteristic of the valve in the process of establishing rail pressure is concluded.Applying the workspace of the valve into the control strategy of rail pressure,experiment shows that the control results is better than before.The drive circuit of flow control valve is simulated by using software Multisim,and the factors that influence the flow rate through the valve is studied based on that.