（1） Working principle of automobile fuel system

We know that the "heart" of the car is the engine, and the fuel system is like the blood that provides work for the "heart", which is the prerequisite for the stable driving of the car. The main working principle of the fuel system is to store gasoline and transport oil and gas into the engine. When the car starts, the fuel system is controlled by ECU to suck the gasoline in the fuel tank through the oil pump, and then transport it through the oil circuit through filtration, The atomized oil and gas is then supplied to the engine through the fuel injection nozzle.

Then, under the action of the electric spark plug, ignite the combustion to generate power to drive the piston to move, and then operate again and again. In this process, the fuel system needs to continuously provide atomized oil and gas for the engine. At the same time, through the control system of the fuel system, corresponding changes will be made to the mass production of oil and gas. At this stage, with the implementation of the national VI emission standard, higher requirements are put forward for the evaporative emission of the fuel system. Therefore, the fuel system also plays a role in reducing fuel evaporative pollution in addition to supplying oil to the engine.

The gasoline vapor in the fuel tank is absorbed through the carbon canister, and the fuel vapor absorbed in the carbon canister is desorbed through the operation of the engine to prevent the fuel vapor from being discharged into the atmosphere through the carbon canister. Nowadays, the automobile manufacturing technology has been greatly improved. The addition of various sensors makes the fuel system work more convenient and smooth, effectively ensuring the normal operation of the engine, thus providing users with a better experience and safety.

（2） Main components of automobile fuel system

The first is the fuel supply system. Generally, it is mainly composed of fuel tank, evaporation pipeline, carbon tank pipeline, fuel pump, fuel supply line, etc. the fuel tank is divided into metal fuel tank and plastic fuel tank. The plastic fuel tank under the national VI standard needs to meet the 6-layer structure, which is an oil storage structure. As an important part of the fuel supply system, the fuel pump is designed to integrate sensors, valves and other components as much as possible, The pipeline design mainly adopts low permeability multi-layer materials, with good sealing structure to reduce system emissions.

At the same time, it also reduces the use of rubber pipes. In the national VI standard, the design of carbon canister assembly is very important. Its main function is to absorb fuel vapor so that it will not be discharged into the atmosphere. Therefore, the volume of activated carbon increases correspondingly. The main function of these structures is to provide fuel and sufficient oil pressure for engine operation. Generally, after the whole vehicle is powered on, ECU will control the fuel pump to establish the oil pressure required by the engine through the pressure regulator according to the actual situation of the vehicle, so as to ensure that clean fuel is provided after the engine is started.

The second is the fuel evaporation system, which is mainly composed of carbon canister, carbon canister adsorption pipeline, carbon canister desorption pipeline and air filter. The main function of the fuel evaporation system is to absorb the gasoline vapor generated in the fuel tank, and suck the gasoline vapor into the engine for combustion through engine desorption, so as to reduce the pollution caused by fuel evaporation. Moreover, the sensors and actuators in the fuel system mainly include fuel tank pressure sensor, carbon canister solenoid valve and carbon canister stop valve. These sensors and actuators are mainly used for OBD diagnosis of national VI fuel system to ensure that they can feed back to ECU and inform the driver in time in case of fuel system failure.