What is the EFI system of a car?
Electronic fuel injection system (Electronic Fuel Injection, EFI) - referred to as gasoline injection.
It is an advanced fuel injection device adopted by the gasoline engine without the carburetor. The electronically controlled gasoline injection technology is popularized from the gasoline engine. During the formation of the gasoline engine mixture, the atomization of the liquid fuel is improved. More importantly, it can be Changes in operating conditions precisely control the amount of fuel injected so that combustion will be more complete, thereby increasing power, reducing fuel consumption, and meeting emission regulations.
The composition of the electronically controlled gasoline injection system
The electronically controlled gasoline injection system is mainly composed of three parts: the air system, the fuel system and the control system. The following figure shows the composition of the electronically controlled fuel injection system.
Air supply system
The air system of the mass flow injection system is composed of an air filter, an air flow meter, a throttle body, an air valve and a surge tank.
Function: Provide clean air for the engine and control the air supply when the engine is working normally.
Principle: After the air is filtered by the air filter, it enters the intake manifold through the air flow meter and the throttle body, and then is distributed to each cylinder through the intake manifold.
Fuel supply system
The fuel system is mainly composed of fuel tank, fuel pump, fuel filter, pressure regulator and fuel injector.
Function: supply fuel with a certain pressure to the injector, and the injector injects fuel according to computer instructions.
Principle: The electric fuel pump sucks the gasoline out of the fuel tank. After being filtered by the filter, the pressure is adjusted by the pressure regulator and sent to the fuel injector through the fuel pipe. The fuel injector sprays fuel into the intake pipe according to the computer command. The excess gasoline supplied by the fuel pump flows back to the fuel tank through the return pipe.
The control system is mainly composed of sensors, input/output circuits and microcomputers. ECU is the core of the control system.
The ECU determines the basic fuel injection time according to the air flow meter signal and the engine speed signal, then corrects the fuel injection time according to other sensors, and sends a command to the fuel injector according to the final determined total fuel injection time to make the fuel injector inject fuel or oil cut.
6 advantages of electronically controlled fuel injection systems
(1) The use of electronically controlled fuel injection technology reduces exhaust pollution, reduces the fuel consumption of the engine, and can meet the requirements of stricter emission regulations.
(2) The ECU electronic control unit responds quickly to the change of the throttle valve, which improves the handling performance and acceleration performance of the motorcycle, and can maintain a good dynamic performance index.
(3) Since the ECU system controls very precisely, the knocking tendency of the engine is reduced, thus allowing the engine to adopt a higher compression ratio, thereby improving the thermal efficiency of the engine.
(4) It is easy to start, especially for cold start in low temperature environment in winter. The electronic control device controls the air-fuel ratio of different working conditions by the computer program, abandons the carburetor-type choke start device, and makes the cold car start more reliable.
(5) It is convenient to adjust the engine performance, which can easily set the fuel quantity and ignition time of the engine under different working conditions, so as to meet the requirements of the engine performance under various road conditions when the motorcycle is running.
(6) The EFI system has strong adaptability. For different types of engines, only the "map" in the ECU chip needs to be changed, and the nozzle ECU of the same oil pump can be used in many products of different specifications and models. The EFI technology can be extended on other types of engines.