Investigation On Injection Characteristics Of Pressure Amplified Electronic Control Injector For Small Bore Low-speed Diesel Engine

With the implement of IMO Tier 3, in order to satisfy Marine diesel engine emission regulations, using high pressure common rail fuel system technology to improve economy and emissions is the main study direction of Marine diesel engine over the years. Pressure amplified electronic control injector with both traditional common rail injector system high injection pressure, can realize multiple injection, cyclic injection volume control advantages of high precision and high control flexibility, as well as the demand of common rail system common rail pipe and oil transfer pump is low. Therefore, carry out study in pressure amplified electronic control injector is the forefront of technology of common rail system research, which has an important significance for engineering applications.Firstly, carry on the conceptual design of pressure amplified electronic control injector,and according to the concept drawings established the AMESim hydraulic simulation model.In order to make electronic control pressure amplified injector dynamic response satisfy the needs and optimization on the basis of the structure, proceed multi-objective optimization on the pressure amplified electronic control injector structure parameters for the needle valve response. In the whole working conditions, the time of needle valve open degree improvement is greater than 2.064%, close delay time improved more than 10,892% in step by step optimization.In global optimization, open delay time ameliorated more than 0.492%, close delay time accelerated more than12.093%. Response delay time improvement degree of the optimized pressurization piston is bigger in step by step than global optimization, but, after the global optimization the needle valve response latency improvement degree is greater.Next, carry on pressure amplified electronic control injector fuel injection quantity influence factors researching. By studying the coupling effects between structure parameters on cycle fuel injection quantity, small quantity injection ocharacteristic analysis and the influence of three times injection interval measurement under the rated conditions influence on cycle fuel injection quantity fluctuation characteristics, obtained the law of coupling effects between structure parameters have on cycle fuel injection quantity. Found out that pressure amplified electronic control injector fuel injection quantity trend along with the change of control pulse width complexly, meanwhile act out nonlinear phenomenon. At the same time, acheved the injection interval of the influence law of fuel injection quantity, found the effects of the previous injection on time after injection is mainly caused by the previous injection fuel pressure fluctuations within the tank.In the end, contrapose the pressure amplified electronic control injector dynamic response responses in multi-injection conditon, the influence of part characteristic parameters on pressurization piston dynamic response and needle valve dynamic response were studied.Found out that pressurization piston big end and small end diameter and tubing diameter before the plunger chamber have remarkable influence on pressurization piston return response. Residual air gap fuel control solenoid valve, control chamber inlet hole diameter, outlet hole diameter, pipe diameter before fuel sump, needle valve lift and nozzle diameter were the important parameters affecting the needle valve response.