The Control Strategy Of High Pressure Common Rail Diesel Engine Fuel Injection Quantity Based On Demand Torque

With the increasingly serious problems of energy consumption and environmental pollution, the development of diesel engine has been put forward higher requirements. High pressure common rail fuel injection system with flexible injection rules, good atomization effect of fuel and other prominent features which provides the necessary conditions for the control of the law of heat release help the engine achieve the optimal power, economy and emissions. This paper based on in the study of the relevant literature and research group preliminary results, using the Great Wall 2.8T high pressure common rail diesel engine combined with the domestic electronic hardware unit, develop and verify the control software. In this paper, the development and experimental research of the control strategy for the identification and switching of the operating conditions and the normal operating conditions are completed. The main contents and results are as follows:For the operating division of diesel engine working condition, set the conditions identification and conversion relation. Proposed the switching control procedure and designed the conditions identification and switching control strategy. The condition identification and switching control strategy are modeled and simulated by using Simuink/Stateflow software, and the correctness of the control model is verified. Finally, the control strategy was programmed and carried out on the engine bench.From the car’s running conditions and heat conversion of diesel engine, power demand and fuel combustion process were analyzed respectively. The fuel injection quantity control of high pressure common rail diesel engine based on demand torque was put forward, which realize the conversion of the external power demand to the engine fuel injection. The determination method of torque, friction torque, high pressure oil pump loss torque, indication torque and torque oil transfer coefficient are analyzed, and set the related MAP.The injection timing control strategy was designed to determine the injection quantity, injection timing and injection time. The control strategy was studied and carried out on the engine bench. The engine can achieve stable operation under normal operating conditions. By comprehensive adjustment of the target rail pressure, injection timing and torque oil transformation map, the engine can realize the target demand torque output according to the operator intention.The control method of rail pressure was based on parameter self-tuning PID control algorithm. The feed forward control was set up to improve the system response and anti-disturbance. By calibrating the control parameters of the rail pressure PID control, the deviation of rail pressure and the target rail pressure was no more than 5% and had a good response.