How do diesel injectors work?

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

As you know, for the operation of an internal combustion engine, oxygen and fuel are needed in a certain proportion. The fuel supply process itself is different for gasoline and diesel cars. In the latter case, the role of injection is performed by nozzles. Diesel engines are equipped with different types of these elements. In today's article, we will look at what these nozzles are, what types they are and whether they can be repaired.

Characteristic

So let's start with a definition. The injectors of diesel engines are an element of the power supply system, which ensures the supply of fuel to the combustion chamber of the cylinder. The mechanism produces a flare spray of the mixture in the volume above the piston.

Also diesel injectors produce fuel dosing. During operation, the element can open and close up to a thousand times per minute.

Types

There are several types of these mechanisms:

• Electro-hydraulic.
• Piezoelectric.

How do these elements work and are arranged in a diesel engine? Below we will look at the features of each of them.

Electro-hydraulic

These diesel injectors are fitted to cars with common rail injection. The device of this mechanism assumes the presence of such elements:

• Control camera.
• Drain and intake choke.
• Solenoid valve.

How do electro-hydraulic diesel injectors work? Their algorithm of action is based on the use of fuel pressure during injection and its termination. So, in the initial state, the nozzle valve is closed and de-energized. And the needle of the mechanism is tightly pressed to the seat under fuel pressure. In this position, no fuel is injected into the cylinders.

The nozzle is controlled by electronics. A special control unit generates a signal that is fed to the solenoid valve. At this time, the drain throttle of the diesel injector opens. Fuel flows out through it and enters the drain line. The intake throttle blocks the rapid equalization of pressures in the intake manifold and the control chamber. Further, the needle rises relative to the saddle and the fuel enters the chamber. Then, from the force of pressure, it ignites, and a working stroke occurs. The nozzle itself returns to its original position. Then the cycle of the mechanism is repeated.

Piezoelectric

These nozzles have a more advanced design. The main advantage of piezoelectricinjectors lies in their responsiveness. The mechanism's solenoid valve operates four times faster than its hydraulic counterparts. This makes it possible to produce multiple injection of fuel in one cycle. The piezo injector is installed on the new generation Common Rail systems.

The control of this mechanism is based on changing the length of the piezocrystal under a certain voltage. The design of the piezoelectric injectors includes:

• Pusher.
• Needle.
• Changeover valve.
• Piezoelectric element.

All this is housed in a small case. The principle of operation of the element is based on the use of hydraulics. As in the previous case, the needle is seated on the saddle due to fuel pressure. But as soon as a signal enters the mechanism, the length of the piezoelectric element increases. This is how the diverter valve opens. Diesel fuel enters the drain line.

The needle rises due to the high pressure that has formed at the bottom. This is how fuel is injected. The compression, stroke and exhaust strokes are similar. But the amount of diesel that is injected is determined by the fuel pressure in the fuel rail and the duration of exposure to the piezoelectric element.

Repair

The main elements that fail are:

• Cartoonist. It is the main element of the Bosch injector. Consists of stem and seat. The last element wears out and breaks. Alsoa stock is also produced. And if the saddle is restored, then it is not possible to repair diesel injectors with a broken stem. This item is non-refundable. In this case, the multiplier must be replaced.
• Atomizer. The manufacturer "Bosch" gives a guarantee for its trouble-free operation for one hundred thousand kilometers. But in our conditions, the atomizer nurses much less. It begins to jam or pour fuel into the cylinder. How is this issue resolved? In most cases, ultrasonic cleaning of diesel injectors helps (because they get dirty on our fuel). But if this operation does not help, the atomizer is replaced with a new one.

Diesel injector repair may not be required for your vehicle. It is enough to make the correct adjustment. But beforehand, diesel injectors are checked on specialized equipment. The essence of the adjustment is simple.

It consists in setting the stroke of the solenoid valve and the ball. The gap is adjusted using shims. Depending on the type of nozzle, the stroke of the ball element can be from 0.025 to 0.07 mm. After that, the valve stroke is set. It should be noted that these operations are performed at specialized service stations. It is impossible to perform such an operation at home.

Conclusion

The nozzle is an important element of any diesel car. The operation of the entire engine depends on its serviceability. Therefore, it is important to diagnose andif necessary, repair diesel injectors. However, the device of this mechanism does not allow such work to be done independently.