Rail Pressure Algorithm Design And Diagnostic Strategy Research For Key Components Of The Common Rail Electronic Control System

Due to High Pressure Common Rail Fuel Injection System (CRS)’s functionality of controlling injection pressure, injection quantity, injection timing and injection rate independently and flexibly, it has huge advantage in terms of power, economy and emissions, which makes it became the best choice to meet the increasingly stringent emission regulations. Based on it, the thesis has finished the rail pressure algorithm design and fault diagnosis and protection for rail pressure and the Electronic Throttles of the CRS.Firstly, the development history of the diesel engine electronic control system were introduced in the thesis, especially the development status and trends of CRS. Then the mechanical assembly and its working principle were elaborated based on the Third-generation of Bosch’s common rail injection system(CP3rotor pump). The pressure wave characteristics in pipe bore, caused by injections, are deeply studied in pump test bench. And referring to the driving characteristics and fuel supply characteristics plunger high pressure fuel pump (PCV valve) used in the High-pressure common-rail system which is developed by the research group, not only feedforward but also PID control algorithm for pressure control are completed, the Matlab/Simulink and RTW Embedded Coder tool sets are used to implement the control strategy modeling and automatic code generation, thus enhances the control software’s portability. Then the experiment of rail pressure control was finished on diesel test bench. So the effectiveness of rail pressure control strategy was validated.Based on the design of rail pressure control algorithm, and research of the possible cause of the rail pressure fault, fuel injection pressure fault diagnosis and protection module were designed, including fault judgment, fault debouncing, fault self-healing. The effectiveness of the fault diagnosis and protection module was validated through experiments of rail pressure fault simulation.The electronic throttle has been widely used due to the advantages to achieve a precise control of the fuel injection quantity, etc.,. Through a comparative study of the two throttle signals, the limit fault and the reasonableness fault diagnosis strategy of the electronic throttle were completed, then the experiment of varieties of electronic throttle fault diagnosing was finished. The results show that diagnosis method can identify the various fault, the corresponding protection strategy can work timely which improved the system reliability and safety.