Engine
Fuel feed system
10.
1.
Pressure rod
2.
Pin
3. Nozzle
4.
Coil
5. Pilot valve
6. Ball plunger
7. Control area
8. Supply volume
9. Control volume
10.
Fuel outlet connector (low pressure)
11.
Control port
12.
Supply port
13.
Electrical connection
14.
Fuel input connector (high pressure)
15.
Spring
Bravo- Btava
@» -™
2000 range
INJECTORS
The injectors are fitted to the cylinder head
and are electromagnetic in type. They are
controlled directly by the injection control
unit.
The injectors come with a high-pressure sup-
ply port and a recirculation pipe at environ-
mental pressure; The supply port is connected
to a delivery manifold (rail) with pipes de-
signed to withstand the high service pressures.
The injector can be divided into two parts:
- Actuator/spray made up of a pressure rod
(1),
pin (2) and nozzle (3);
- control solenoid made up of coil (4) and
pilot valve (5).
Operation
Injector operation may be divided into three
stages:
7. rest position
Coil (4) is deactivated and plunger (6) is in
closed position to prevent fuel entering the
cylinder: Fc > Fa where Fc is the force gener-
ated by pressure acting on the control area (7)
of pressure rod (1) and Fa is the force due to
the pressure acting on supply volume (8).
2. Start of injection
Coil (4) is excited and causes plunger (6) to
rise.
Fuel flows from control volume (9) to
the return manfold to bring about a pressure
drop in control area (7). Simultanteously, line
pressure through supply port (12) exerceses a
force Fa > Fc on supply volume (8) to cause
pin (2) to rise and thus allow fuel into the
cylinders.
3. end of injection
Coil (4) is deactivated and causes plunger (6)
to return to closed position. The resulting
bal-
ance of forces makes pin (2) return to rest po-
sition and injection therefore ends.
14
Print n° 506.670/22
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