3 Type of Fuel Injectors With Difference and Definition

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Electronic fuel injection (EFI) system has been applied to almost all recent vehicles. The good performance and economical fuel uses are the main reasons why EFI systems are implemented.

The fuel injection system works using an injector, where each injector will spray fuel with an ideal volume in the intake manifold.

The content about the injector we discussed earlier, you can read here; Understanding Fuel Injector Working Principle

However, do you know that the fuel injector consists of several types.

This is what will be our topic, so read more below

Type Of Fuel Injector On Engine


There are three types of injectors that are most commonly used (either on diesel engines or petrol engines), namely, spring type injectors, magneto injectors, and pizeo electric injectors

1. Spring type injector

As the name suggests, spring type injector is an injector that use spring. The spring properties is flexible, and this flexibility is used to press the nozzle to close.

Maybe you already understand, the injector can spray fuel because there is a small gap in the nozzle. In the OFF condition, the gap will be closed but when the injector is ON, the gap is open and the fuel is sprayed.

In this type, the spring is used to press the nozzle to close the gap. But when the fuel pressure rises spontaneously, the spring will rise. That causes the nozzle to lift and the gap is open.

Simply, the diagram is as shown below


From the picture above, it show there is a spring inside the injector body. Under the spring there is a shim, while in the bottom is a nozzle.

Shim has a functions to recover the injector performance, this is because the spring elasticity will weaken when the injector is used continuously. If the spring weakens, the gap on the nozzle will be wider. And this causes less fuel atomization.

So as a recovery, a thicker shim is used.

Spring type injectors are used in conventional diesel engines, this type requires a high pressure pump with individual controls.

So before ignition timing is achieved, the fuel pressure inside the injector is low. This makes the spring press the nozzle to close. However, when ignition timing is achieved, a high pressure pump will increase fuel pressure spontaneously.

It can be said that the injector becomes passive part, because the controller of fuel spray is a high pressure pump.

2. Magneto injector

Magneto injector is a type of injector that uses magnetism to open the nozzle gap.

It is also called a solenoid injector, because it uses a solenoid to produce magnetism.

Magneto injector works when the solenoid is given a voltage, magnetism will occur. The magnetism will move the iron core in the middle of the solenoid.

The movement of the iron core will open the nozzle gap.

In simple terms, the magneto injector diagram is as follows.


From the picture above, it can be seen that the injector control is located on the solenoid. When solenoid is OFF, the nozzle gap is closed but when the solenoid is ON the nozzle is opened.

The most striking difference is in fuel pressure. In the first type,the  typical of fuel pressure is frequency because the pressure will rise when ignition timing is achieved.

But on the magneto injector type, the fuel pressure is made stable to keep it high because each injector will spray it.

This type of magneto is the most common type used in all vehicles, either diesel (common rail) or petrol engine (EFI).

3. Pizeoelectric injector

img by caranddriver.com

Basically, the third type is the same as the magneto injector where the main control is located on the injector.

However, the injector does not use magnetism to open the nozzle gap but uses special material that can deflate when energized.

The material is piezeo slice, when given a voltage of thousands of pizeo slices inside the injector body will collapse. The deflation will pull the nozzle up, and it make the nozzle gap is openned.

This type is new so that only a few manufacturers use this type of injector.