Function of Nozzle of 750kw Diesel Generator Set

The fuel injector of diesel generator set refers to the fuel injector (or nozzle and oil head) of diesel engine.

To clarify the function of fuel injector in diesel engine, it needs to be explained from the working principle of diesel engine. Diesel engine belongs to compression ignition internal combustion engine. Gasoline engine belongs to ignition internal combustion engine. Their work and design parameters are different, so I won't repeat them here.

An ordinary four-stroke diesel engine has four strokes per cycle. They are intake, compression, explosion and exhaust.

In the intake stroke, the piston moves downward, the cylinder volume increases, the intake valve of the diesel engine opens, and fresh air from outside enters the cylinder through the intake valve; When the piston reaches the bottom dead center, it starts to move upward, the intake valve closes, the cylinder volume becomes smaller, the air in the cylinder is compressed, and the temperature rises sharply. When the piston reaches the top dead center, the fuel is injected into the cylinder through the fuel injector, which burns (explodes) instantly, and the volume of combustion gas in the cylinder expands rapidly, pushing the piston to move downward. Rotate the crankshaft through the connecting rod to output power. After the piston reaches and crosses the bottom dead center again, it moves upward again. At this time, the exhaust valve is opened, and the combustion exhaust gas in the cylinder is discharged. A cycle ends. After passing the top dead center, the piston enters the intake stroke again and starts the next working cycle.

In the working process described above, we can see that the function of the fuel injector is to inject fuel into the cylinder at the right time.

There are several explanations:

1. Considering that there will be a certain delay between fuel entering the cylinder and combustion, fuel should be injected before the piston reaches the top dead center. That is, the fuel injection has an advance amount (advance angle) with respect to the top dead center. It is called injection timing.

2. In order to make the fuel entering the cylinder burn fully, the fuel entering the cylinder must be atomized to maximize the surface area of the fuel in contact with high temperature air. Due to insufficient combustion of poorly atomized fuel, unburned carbon molecules are discharged with exhaust gas, forming "black smoke".

3. In order to atomize the fuel entering the cylinder, the fuel pump provides high-pressure fuel to the injector.