Research On Characteristics Of Electro-hydraulic Delaying Of EUP Fuel Supply System

Due to the non-negligible delay factors in fuel system, the electric delaying characteristics of electromagnetic valves and hydraulic delaying characteristics of oil passages, both of which have a deep influence on oil injection process, must be accurately calibrated. Based on that, an injection impulse signal control model is established, and the correct timing sequence of electromagnetic valves is determined. This paper introduced the development of oil systems with EUP, and compared with other oil systems. The mechanism and principle of the EUP is introduced, and then based on the analysis of operational parameters, controlling parameters and structural parameters by combining experiment and model simulation, the oil injection and electro-hydraulic delaying characteristics are studied. The main research includes:Firstly, an oil pump testing bench is established, and the rotation speed and injection impulse width-dependent variation curves of current, oil injection pressure, injection velocity and the lift range of pin valve in the injector are measured. By processing the data, different electro-hydraulic delaying curves are obtained, and then its cause is discussed.After that, the control current is changed, including peek value and maintaining value. The effect laws of current on oil injection characteristics are studied at first, and the optimal peek value and maintaining value of oil system are obtained. Meanwhile, the peek value and maintaining value-dependent variation curves of oil injection pressure, injection velocity and the lift range of pin valve in the injector are measured and processed. The respective electro-hydraulic delaying curves are obtained, and the causes are discussed. As to controlling parameters, electro-hydraulic delaying characteristics under different advance angles of fuel supply are studied. And the correspondent variation reasons are discussed.Finally, the simulation model of electronic EUP is established, and calibrated by experiment data. The average relative error is less than 5%, which guarantees the validity of the model.The structural parameters are studied by using the calibrated model, including cone angle and middle part diameter of valve handle, inclined oil channel and secondary inletting passages in valve seat, length and diameter of high pressure pipeline, opening pressure and nozzle orifice of injector, etc. The variation curves of oil pressure injection velocity and the lift range of pin valve in the injector are obtained through simulation, and then the causes of correspondent electro-hydraulic delaying characteristics are studied by processing the simulation data.