Injectors

1. Pressure rod
2. Pin
3. Jet
4. Coil
5. Valve
6. Shutter with ball
7. Control area
8. Supply volume
9. Control volume
10. Fuel outlet connector (low pressure)
11. Control manifold
12. Supply manifold
13. Electrical connection
14. Fuel inlet connector (high pressure)
15. Spring

INJECTORS

The injectors, fitted on the cylinder head, are the electro-magnetic type, operated directly by the injection control unit.

The injectors are equipped with a high pressure supply duct and a recirculation pipe at ambient pressure; the supply duct is connected to the supply manifold (rail) with pipes designed to withstand the high operating pressures.

The injector can be divided into two parts:

• actuator/nozzle consisting of a pressure rod (1), pin (2) and jet (3);
• solenoid valve consisting of a coil (4) and valve (5).

Operation

The operation of the injectors can be divided into three stages:

1. rest position

The coil (4) is de-energized and the shutter (6) is in the closed position and does not allow the introduction of fuel into the cylinder: Fc>Fa where Fc is the force produced by the pressure which acts on the control area (7) of the pressure rod (1) and Fa is the force produced by the pressure acting on the supply volume (8).

2. start of injection

The coil (4) is energized and raises the shutter (6). The fuel flows from the control volume (9) to the return manifold causing a decrease in pressure in the control area (7). At the same time, the line pressure through the supply manifold (12) exerts a force Fa>Fc on the supply volume (8) raising the pin (2) with the consequent introduction of fuel into the cylinders.

3. end of injection

The coil (4) is de-energized and returns the shutter (6) to the closed position which restores a balance which returns the pin (2) to the closed position and consequently the injection ends.