8
SECTION 2 - OPERATING DIAGRAMS
CURSOR SERIES
Base - 03/2015 Print P4D32C006 E
Figure 7
190508
1 Coil - 2 High pressure fuel intake fitting - 3 Filter - 4 Pressure rod - 5 Needle - 6 Nozzle -
7 Pressure chamber - 8 Fuel return - 9 Control volume - 10 Pilot valve shutter
The electro-injector may be considered as mainly made up of two parts:
- actuator/spray nozzle consisting of pressure rod (4), needle (5) and nozzle (6).
- control solenoid valve, consisting of a coil (1) and pilot valve.
Electro-injector operation is divided into three phases:
1
st
Phase - Resting position
The coil (1) is not energised and the shutter (10) of the pilot valve is closed.
Under this condition, opening and closing forces are balanced as fuel pressure in the control volume (9) equals that of the pressure
chamber (7).
2
nd
Phase- Injection start
The coil (1) is energised and causes the shutter (10) to rise.
The fuel of the control volume (9) flows off towards the return manifold (8) causing a drop in pressure.
Simultaneously, the line pressure exerts an opening pressure in the pressure chamber (7) that lifts the needle (5) thus causing
fuel to be injected into the cylinders.
3
rd
Phase - End of injection
The coil (1) is de-energised and makes the shutter (10) return to its closed position. This creates a balance in the forces acting
upon the needle (5), causing it to return to its closed position and consequently halt the injection of fuel.
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