Introduction to fuel injector

The fuel injector receives the fuel injection pulse signal sent by ECU to accurately control the fuel injection quantity.

Fuel injector is a kind of precision device with very high machining precision, which requires large dynamic flow range, strong anti blocking and anti pollution ability and good atomization performance.

Electronically controlled fuel injector is the most critical and complex component in the common rail system, and it is also the component with the greatest difficulty in design and process.

By controlling the opening and closing of the solenoid valve, the ECU injects the fuel in the high-pressure fuel rail into the combustion chamber with the best injection timing, injection quantity and injection rate.

In order to achieve effective injection starting point and accurate injection quantity, the common rail system adopts a special injector with hydraulic servo system and electronic control element (solenoid valve).

The fuel injector is composed of a hole type fuel injector similar to the traditional fuel injector, a hydraulic servo system (control piston, control orifice, etc.), a solenoid valve, etc

Structural principle of fuel injector

Type and structure of fuel injector:

a. According to the structure of fuel injection port, it can be divided into shaft needle type and hole type

b. According to coil resistance value: high resistance (13 ~ 16 Ω), low resistance (2 ~ 3 Ω)

c. By use: MPI, SPI 6

d. By fuel position: upper end oil supply type, side oil supply type

Fuel injection process:

a. The fuel injector acts as a solenoid valve

b. When energized, the electromagnetic coil generates electromagnetic force, the armature and needle valve suck up, the fuel injector opens, and gasoline is injected into the air inlet or intake pipe through the injection hole

c. When the power is off, the electromagnetic force disappears, the armature and needle valve close the injection hole under the action of the return spring, and the fuel injector stops fuel injection.

d. The power on and power off of the fuel injector are controlled by the electronic control unit with electric pulse.

e. The injection quantity is determined by the electric pulse width. Pulse width = injection duration = injection quantity

f. Generally, the lift of needle valve is about 0.1mm, and the injection duration is within 2 ~ l0ms