Research On Modeling And Simulation Of The Fuel Common Rail System Of Marine Electronic-Control Diesel Engine

In order to meet the increasingly stringent emission regulations, as well as improve the economical efficiency, operational reliability and flexibility, the requirement on the control of marine diesel engine is higher and higher. The key point in improving the operational performance and reducing the emission is improving the combustion process, in which the fuel system plays a very important role. So common rail injection technology has become one of the inevitable trends of fuel system of marine diesel engine. Through the simulation of common rail system of marine diesel engine can solve many technical problems in the research and development of common rail system effectively. The simulation model can not only guide bench scale test, applied to the development and design of the simulator, used for crew training platform, but also shorten the cycle in the development and design of common rail system and save a lot of manpower, material resources and financial resources.This paper selects the study on simulation of the fuel common rail system of marine diesel engine as its main topic. It mainly interprets Sulzer RT-flex common rail system of marine diesel which includes the fuel system, starting air system and exhaust valve drive system, and introduces the main components of the fuel common rail system (supply unit, common rail unit and Injection controll unit ) and Wartsila Engine Control System (WECS-9500 control system)'s composition, working principle, and the control functions refer to the diesel engine and cylinder.Establishing a mathematical model of the fuel common rail system on the basis of the basic principles of fluid mechanics, including the calculation of the fuel rail pressure, the fuel injection control valve (including the control valve motion equation,fuel quantity piston motion equation and the fuel injection quantity), the pump quantity of high pressure oil pump, the fuel injection quantity of the nozzle and fuel injection nozzle.Making modular modeling of common rail diesel fuel system in use of Matlab / Simulink 7.0 software, simulation models include fuel rail module, fuel rail valve module, fuel injection nozzle module, injection timing module and injection control module. By taking the cylinder compression pressure, injection timing and fuel injection quantity as boundary condition and making linear interpolation with look-up method, it comes to the relevant parameters under different operating conditions.Obtaining fuel rail pressure curve and injection cavity pressure curve of the fuel common rail system under typical operating condition through simulation, which reflect the rail pressure fluctuation, injection timing and injection duration under different operating conditions. It concludes how the the fuel rail operating pressure, injection quantity and common rail volume affect rail pressure fluctuations.Based on the common rail fuel system simulation, this paper obtains relatively accurate model of the fuel common rail system, which is valuable for simulation calculation, optimization design, simulators development and crew training.