Solenoid Valve Modeling And Rail Pressure Control Of Common Rail System For GDI Engine

With the increase in car ownership, energy consumption and environmental pollutionproblems caused by automobiles have become two popular huge challenges. In order toachieve the goal of energy conservation, engineers have introduced many new technologiesto improve the engine performance. Gasoline engine direct injection (GDI) technology hasattracted many engineers concern at home and abroad as one of the new car technologiesof energy saving and emission reduction.GDI engine common rail system has higher rail pressure, and the fuel is injecteddirectly into the cylinder, thereby fuel direct injection can avoid injection gasoline engineinlet wet wall efect, and increase the engine working efciency. However, for the GDIengine common rail system pressure fluctuations will cause engine performance degrada-tion, even severely damage to the engine. So the GDI engine common rail system railpressure control is one of the key issues afecting the development of the direct injectiontechnology. The rail pressure control of the main purpose is to achieve a certain high railpressure, and the pressure fluctuates as small as possible. In this paper, the rail pressurecommon rail system for GDI engine control, a rail pressure control system is designed byusing model-based controller design ideas.According to the structural characteristics of the common rail oil system, it is dividedinto two parts including the actuator solenoid valve and the plant with high-pressurepump-common rail-injector. The actuator high-pressure pump front end solenoid valve isdescribed in detail, according to the operating characteristics of the solenoid valve, anddivided into three parts of the’electric’,’magnetic’, and’machine’, and in turn subsystemsmathematical models are established. Then, the laboratory previous foundation–the highpressure pump-common rail-injector model is described briefly, based on the fluid bulkmodulus formula, which consider flow as the various components of the input and output,and pressure as the state. And in turn the state equations of high-pressure pump, commonrail and injector are brought out.Then, in term with the working features of the plant system and the implementation,Concerning outer loop intake fuel flow control algorithm based on existing laboratory, integrating the original output injector flow in a single injector cycle to get the corre-sponding volume amount of fuel entering the solenoid valve, as desired values of the innerloop controller; the solenoid valve control law is designed by feedback linearization basedon the Rolls stability criterion. Connecting outer loop controller, the proposed doubleclosed-loop rail pressure controller is designed.To verify the controller efect, firstly, respectively in the Simulink and AMESimsimulation environments build a solenoid valve model and embed it into the high-pressurepump in the front end of the controlled plant, then function of the overall system includingsolenoid valve common rail system model is tested simply; after debugging, solenoidvalve and the controlled system can basically meet the functional requirements. Thedesigned double closed-loop rail pressure controller is built both in Simulink and AMESimsimulation environment. And ofine simulation experiment is carried out respectively withthe constant and sinusoidal variation rail pressure, and the control efect basically meetsthe requirements.In term of rail pressure control problem for the high pressure common rail system ofGDI engine, this paper further considers the impact of the actuator on the injection sys-tem, designs a double closed-loop rail pressure controller, and through of-line simulation,control performance is verified well. But also the designed controller increases largely thedifculty of the controller realization. The next step, control algorithms can be simplifiedappropriately, and the part of reflecting the system characteristics can be made up ofthe parameter map, to meet the real-time requirements of engineering applications. Inaddition, the parameters of the model of the common rail system is only partly takenfrom real data, and also need more actual data for improving the reliability of the model.