Fuel Injector Nozzle Types | Full Details.

A fuel injection nozzle is a component of an internal combustion engine that is responsible for delivering fuel into the engine’s combustion chamber. The nozzle is designed to atomize the fuel into a fine mist, which improves combustion efficiency and reduces emissions.

In this article, I will discuss the types of fuel injector nozzles. 

Fuel injector nozzle types

The choice of fuel injection nozzle depends on the engine’s design, performance requirements, and fuel type. There are several types of fuel injection nozzles:

1. Single-hole nozzle 

Single hole fuel injector nozzle.
Single-hole nozzle


The single-hole nozzle has one hole drilled centrally through its body which is closed by the nozzle valve. The hole can be of any diameter from 0.2 mm upwards. A variation of this type, shown in Fig, is known as the conical end nozzle. In this case, the single hole is bored at an angle to the vertical center line of the valve as required. 

2. Multi-hole nozzle 

Multi-hole fuel injector nozzle.
Multi-hole nozzle


The multi-hole nozzle can have a varying number of holes drilled in the bulbous end under the valve seating, their actual number, size, and disposition are dependent upon the requirements of the engine concerned.

3. Long stem nozzles

long-stem fuel injector nozzle
Long-stem nozzles


For direct injection engines where, owing to limited space between the valves in the cylinder head, it is not possible to provide adequate cooling for the standard short stem nozzle, an alternative form of a nozzle with a small diameter extension has been developed.

4. Pintle nozzles

Pintle fuel injector nozzle.
Pintle nozzle


In the case of the pintle nozzle which is designed for use in engine combustion chambers of the air cell, swirl chamber, or pre-combustion type, the valve stem is extended to form a pin or pintle which protrudes through the mouth of the nozzle body. By modifying the size and shape of this pintle, sprays varying from a hollow parallel-sided pencil form up to a hollow cone with an angle of 60° or more can be provided.

5. Delay nozzles

Certain pre-combustion chamber-type engines, while requiring a pintle nozzle, demand different spray characteristics to obtain required running at idling speeds. This is accomplished by modifying the design of the pintle so that a rate of speed is required at the beginning of the delivery, the resultant effect being to reduce the amount of fuel in the combustion chamber when combustion commences, thus diminishing “die to knock”. The modified nozzle is referred to as a “delay” nozzle. It should be noted, however, that this type of nozzle does not necessarily improve idling in every pre-combustion chamber engine, and should be selected only after prolonged tests. 

6. Pintaux nozzle

The Pintaux nozzle is a development of the pintle type, having an auxiliary spray hole to assist easy starting under cold conditions. At engine starting speeds, the nozzle valve is not lifted sufficiently to clear the pinhole, and the fuel is discharged through an auxiliary hole. At normal running speeds, however, when the pressure in the fuel system is higher, the nozzle valve is withdrawn from the pintle hole allowing the bulk of the fuel to be discharged through it. 
The fuel injector nozzle is the most important component inside a cylinder. The injector nozzles are responsible for throwing the fuels at a pressure that can atomize the fuels before getting mixed with the air. So, the responsibility of the fuel injector nozzles is important for the combustion.

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