Research On Control Strategy Of Fuel Injection System Of Marine Medium-Speed High-Pressure Common Rail Diesel Engine

The high-pressure common rail electronically controlled injection system has become an effective method to reduce diesel emission and fuel consumption by virtue of its huge advantages in improving the performance of diesel engines.In this paper,the Marine medium-speed high-pressure common-rail electronically controlled diesel engine is taken as the research object.Based on the completion of the basic control strategy of the electronic-control system,the control of common rail pressure and fuel injection in the high-pressure common-rail fuel injection system is studied with precision,and the control strategy is verified by the real-time simulation model of diesel engine working process and common rail system.The research contents of this paper mainly include the following aspects:(1)The functional demand analysis of electronic control system for Marine medium-speed pressure common rail diesel engine is completed,the modular basic control strategy was established by using Simulink software,which includes setting speed processing,crankshaft speed calculation,timing synchronization,operating condition management,rail pressure regulation and fuel injection.After the establishment of the basic control strategy,the function verification of the basic control strategy was carried out by using the real-time simulation model of diesel engine working process established by AVL CRUISE M,the results show that the basic control strategy can fulfill the basic control requirement of diesel engine starting,stopping and speed regulation.(2)Aiming at the problem of over-harmonic and delay response in PID control algorithm of common rail pressure,a model-based control strategy of common rail pressure is studied in this paper.The model-based control adopts the method of inverse calculation of control parameters by mathematical model,the fuel supply required by the theory of common rail system was calculated by the control model of electronic injector and pressure fluctuation of common rail system,so as to control the proportional valve of high-pressure fuel pump.Based on the MAP data of the common rail system provided by the AMESim common rail performance simulation model,the real-time simulation model of Simulink common rail system was established to verify the function of common-rail pressure control strategy based on the controlled model,the results show that the control strategy can improve the over-harmonic and response delay of the PID control algorithm.(3)The curve fitting method is used to fit the optimal cylinder pressure curve of diesel engine into a mathematical function composed of different characteristic parameters,to control the inject timing and pulse width of the electronic control injector by PID neural network control system,so as to achieve the working cylinder pressure curve of the diesel engine approximates to the optimal cylinder pressure curve.Through the verification of the real-time simulation model of working process of diesel engine,the control strategy can control the actual cylinder pressure curve approximates to the target cylinder pressure curve of diesel engine.