Diesel Injectors Explained

What is a Diesel Injector?

A diesel injector is a vital mechanical component within a diesel injection system. Its job is to deliver diesel into the engine cylinders in the form of a fine, atomised spray.
 

Diesel Injector Components

Nozzle

The nozzle is the part of the diesel injector which delivers fuel into the cylinder.

Nozzle Body/Nozzle Holder/Injector Body

The part of the diesel injector which houses the nozzle needle, nozzle and nozzle spring.

Needle valve

A valve between the tip of the nozzle needle and the injector body. The valve is held closed by a spring. When open, the valve allows fuel to be sprayed into the combustion chamber. When closed, the valve and needle form a seal.

Pressure Chamber

The pressure chamber surrounds the needle valve. When the pressure built up in the chamber is sufficient enough to overpower the spring, the spring will compress and lift the nozzle needle and open the needle valve.

Diesel injection explained

Diesel is delivered into the injector via diesel pump.

Fuel passes through a channel in the injector body and into a pressure chamber surrounding the needle valve.

High fuel pressure builds, causing the spring to compress and the needle valve to open.

Fuel is driven through tiny holes in the nozzle tip and is sprayed into the combustion chamber.

Sprays are delivered constantly into the cylinder at a precise and controlled amount.

Some diesel is allowed to return to the fuel tank through a return channel. This can also help to cool the injector.