Research On Control Strategy Of Fuel Injection For A Two-stroke Kerosene Aviation Piston Engine

With the urgent demand of small aircraft power plant at home and abroad, the injection system of electronic control of small aviation kerosene-piston engine has become a hot spot of research in recent years. The quality of fuel injection system of electronic control of the engine depends on the control strategy made in the electronic control unit. So it has important significance to study the control strategy of fuel injection of kerosene engine.Considering the small difference between gasoline and kerosene in physical and chemical properties, and the relatively mature technology of gasoline-piston engine, this paper uses the methods of gasoline piston-engine to study kerosene piston-engine. Specific method of the gasoline engine model was established firstly, and then the injection control strategy was made according to the simulation results from the model, the aim of injection control strategy and the difference gasoline and kerosene. The hardware and software of electronic control unit were designed according to the fuel injection control strategy. Finally, the injection control strategy was verified by bench test. The main research contents are as follows:(1) The type of carburetor piston-engine was modified. The oil way of piston engine was transformed into inlet electronically controlled fuel injection from the type of carburetor. The composition component of electronic control fuel injection system is composed of sensors, driving mechanisms, electronic control unit and control-calibration software. The system mainly provides the platform of soft and hardware for the strategy of fuel injection control.(2) The jet inlet mean model of electronic control gasoline engine was established. And the control strategy of fuel injection was formulated. The Mean Value Engine Model of the engine of intake port fuel injection was built by using software of Matlab/Simulink. Then the model simulation results were verified by the data from the carburetor bench test. The injection quantity of each steadystate operating point was calculated by using the simulation. Fuel injection control strategy of each working state was designed according to the model, the target of control strategy and the difference gasoline and kerosene. Starting condition of open-loop control, idling speed feedback loop control, steady working theory air-fuel ratio control, transient oil film compensation control and over-speed conditions oil interruption control.(3) The software and hardware were designed according to the requirement of control strategy of electronic fuel injection. The parts of hardware mainly include the design of microprocessor minimum circuit, the design of signal conditioning circuit, the design of driving circuit. The software is designed according to the function of each module by using modular method. The main modules include the module of speed calculation, condition processing, analog acquisition, and the calculation module of fuel injection quantity.(4) The control strategy of fuel injection of gasoline piston-engine was verified. First bench test was done if there was no mistake in semi-physical experiment for ECU. Then the dynamometer bench is used to verify whether fuel injection quantity of the stable condition obtained by model can meet the requirement of theoretical air-fuel ratio. And then the conditions of starting, idle speed, steady, transient operating of control strategy of fuel injection were verified by thrust bench.To sum up, this paper studies the control law of small kerosene piston-engine, constructing a set of electronic control unit which is suitable for kerosene piston-engine, and putting forward a set of fuel injection control strategy of kerosene piston-engine during starting condition, idle speed condition, stable condition, transitional condition and speeding condition.