How Does Fuel Injection System Work?

Fuel injection systems on gasoline vehicles are usually indirect, with gasoline being injected into the intake manifold or intake port rather than directly into the combustion chamber. This ensures that the fuel is thoroughly mixed with the air before it enters the combustion chamber. However, many diesel engines use direct injection, where diesel is injected directly into cylinders filled with compressed air. Others use indirect injection, injecting diesel into a specially shaped pre-chamber that has a narrow passage connecting it to the cylinder head. Only air is drawn into the cylinder. It is heated so high by compression that atomized fuel injected at the end of the compression stroke spontaneously ignites. The injectors that inject fuel through the injectors are first screwed into the intake manifold or cylinder head with nozzles and angled so that the fuel injection is directed towards the intake valves.

There are two types of injectors, depending on the fuel injector system. The first system uses continuous injection, where fuel is injected into the intake port all the time the engine is running. The injector just acts as a nozzle, breaking up the fuel into a fine spray - it doesn't actually control the fuel flow. The amount of fuel injection is increased or decreased by a mechanical or electrical control unit, in other words, it is like turning a water tap on and off.

Another popular system is a timed injection (pulse injection), in which fuel is delivered in bursts to coincide with the intake stroke of the cylinders. Like continuous jetting, timed jetting can be controlled mechanically or electronically.

What controls the fuel injectors?

The control method of the automobile fuel injector is as follows: 1. The electronic control device is used for the electronic injection engine. Replace the traditional mechanical system (such as a carburetor) to control the oil supply process of the engine. For example, the EFI system of a gasoline engine measures the temperature and air-fuel ratio of the engine through various sensors; 2. Throttle status, engine speed, load crankshaft position, vehicle driving status, and other signals are input into the electronic control device. According to these signal parameters, the electronic control unit. Calculate and control the fuel injection quantity and fuel injection time required for each cylinder of the engine, and spray gasoline under a certain pressure into the intake pipe through the fuel injector for atomization; 3. It mixes with the incoming airflow and burns in the combustion chamber, thereby ensuring The engine and catalytic converter are always working at their best, involving the vehicle itself, as well as the driver and the road conditions. Generally speaking, there are seven main areas: engine, emissions, transmission, body shape, weight, tires, and driving technique.

What causes fuel injector failure?

1. Poor atomization of the fuel injector: When the fuel injection pressure is too low, the nozzle hole wears and has carbon deposits, the end face of the spring wears or the elastic force decreases, the fuel injector will open early and close late, and cause poor atomization of the fuel injection. Phenomenon.

2. The oil return pipe of the injector is damaged: when the needle valve coupling is severely worn or the needle valve body and the injector shell are not tightly matched, the oil return volume of the injector will increase significantly, and some can reach 0.1-0.3kg/h . If the oil return pipe is damaged or leaked, the return oil will be lost in vain, resulting in waste.

3. Needle valve nozzle hole enlargement: Due to the continuous injection and erosion of high-pressure oil flow, the needle valve nozzle hole will gradually wear out, resulting in a drop in fuel injection pressure, shortened injection distance, poor atomization of diesel oil, and increased carbon deposits in the cylinder.

4. Needle valve seizure: Moisture or acidic substances in diesel oil will cause the needle valve to corrode and get stuck. After the needle valve sealing cone surface is damaged, combustible gas in the cylinder will also rush into the mating surface to form carbon deposits, causing the needle valve to bite. If it dies, the injector will lose its fuel injection effect, causing the cylinder to stop working.