Investigation On Injection Characteristics Of Electronic Unit Pump Using Biodiesel

With the energy crisis and the strict emission regulations,the electronic unit pump(EUP)fuel system has the higher injection pressure,the digital control of the diesel engine to meet the emission and economy requirements.Biodiesel as a clean alternative energy,because of the different properties with conventional diesel,which directly impact the injection characteristics,thereby affecting the diesel engine indicator of economic performance,combustion characteristics and emissions.Studying the EUP injection characteristics fueled with biodiesel,revealing the mechanism and the influence rules of injection characteristics,and by the multi-objective optimization,providing the optimal design scheme of EUP,it is very significance EUP fueled with biodiesel as an alternative energy in engine.The simulation model of EUP was established in the AMESim environment,the injection characteristics analysis of EUP fueled with biodiesel was done with the combination of experiment analysis and numerical simulation.First of all,in all conditions,using the Design of Experiments(DOE)method,through the single factor correlation analysis between different parameters with cycle injection quantity and injection peak pressure variation,obtained the influence key parameters:Cam contour line rate,plunger diameter,solenoid valve spring pre-tightening force,high-pressure oil pipe length,high-pressure oil pipe diameter and orifice diameter,and studied the variation of cycle fuel injection quantity and the injection pressure peak caused by the changes of the above parameters.Second,in all conditions,the author studied the injection characteristics of EUP fueled with biodiesel and diesel,revealed the fuel due to different properties caused by the EUP response speed,injection pressure,cycle injection quantity and the characteristics of equivalent heat.Research showed that:the fuel properties such as the elastic modulus,velocity and viscosity,affect the change rules of injection pressure,fuel injection quantity and the response speed of EUP.Although biodiesel low calorific value is lower than diesel,the fuel injection quantity is larger,offering the same heat to diesel engine,biodiesel need the injection duration less than diesel.Finally,Based on the modeFRONTIER multi-objective optimization platform,according to the response delay characteristics of EUP,carried out the step-by-step and the overall optimization scheme,the needle valve opening and closing response delay time were optimized at the same time,abtained the key characteristic parameters which affect the control response characteristics and the bits of parameters configuration which have the shorter response delay time.In order to improve the injection pressure of EUP and achieve a higher pressure injection,carried out the injection characteristics optimization of EUP,limited cycle injection quantity error within the allowable range,while the higher fuel injection pressure was optimized,obtained the bits of parameters configuration which has the higher accuracy cycle injection quantity and the larger injection pressure peak.According to the response delay of EUP and its injection characteristics,carried out the multi-objective optimization of the response and injection characteristics,the targets were to optimize the cycle injection quantity error minimum,the needle valve response delay time minimum,injection pressure peak maximum,the optimization results show that:the needle valve opening and closing delay time was reduced significantly,the maximum error of cycle injection quantity was 0.446mm~3,the highest optimizing degree of injection pressure peak value reached 62.506%.The above analysis provides a theoretical guidance for the study of EUP fueled with biodiesel.