What is the structure of the fuel injection system of electronically controlled engine?

According to its function, the electronically controlled gasoline injection system mainly consists of three parts: air intake system, oil supply system and electronic control system. (1) air intake system. Its function is to provide necessary air for the engine, which is generally composed of air filter, throttle body, throttle valve, air valve, intake manifold and so on. In addition, in order to adjust the air intake at any time to meet the needs of various working conditions, the air intake system is also equipped with an air intake detection device. In the D-type system, the intake air quantity is detected by the intake manifold pressure sensor; In the L-shaped system, the intake air is detected by the air flow sensor installed behind the air cleaner. Air enters the cylinder through the air cleaner, throttle, intake manifold and intake valve. The air valve is only used to adjust the air intake and control the idle speed of the engine when the generator temperature is low. The throttle assembly includes a throttle passage for controlling air intake and an air bypass passage running at idle speed. The throttle position sensor is connected with the throttle shaft to detect the throttle opening. Some throttle assemblies are equipped with throttle return buffers and air regulating valves. In order to prevent moisture in the air from freezing on the throttle assembly in winter, some also make engine cooling water flow through the assembly. (2) Fuel supply system. It is usually composed of electric gasoline pump, gasoline filter, pressure regulator, pulsation damper, injector and cold start injector. In the electronically controlled gasoline injection system, the gasoline is pumped from the fuel tank by the electric gasoline pump and delivered to the electromagnetic injector and the cold start injector through the gasoline filter. The pressure regulator is connected in parallel with the injector to ensure that the difference (injection pressure difference) between the gasoline pressure in the electromagnetic injector and the pressure in the injection environment is constant. The pulsation damper can eliminate the slight fluctuation of oil pressure during fuel injection and further stabilize the oil pressure. The electromagnetic injector injects gasoline into the air inlet according to the fuel injection pulse signal controlled by the engine. When the cooling water temperature is low, the cold start injector injects gasoline into the intake manifold to improve the low-temperature starting performance of the engine. (3) Electronic control system. The function of the electronic control system is to comprehensively analyze and process the signals of various sensors through the computer, and control the oil quantity through the executive device, so that the engine has the best performance. ECU determines the air flow according to the signals of air flow meter (L-type) or intake manifold pressure sensor (D-type) and speed sensor, then determines the basic fuel supply for each cycle according to the air-fuel ratio requirements and intake signals, and then corrects various working parameters such as ignition advance angle, temperature, throttle opening, air-fuel ratio and so on according to the signals of various sensors, and finally determines the optimal fuel injection quantity under a certain working condition.