FUEL INJECTOR
DESCRIPTION
FUEL INJECTOR
There are individual fuel injectors for all five cyl-
inders. These fuel injectors are used to spray fuel
into the combustion chamber (Fig. 4).
OPERATION
The injector operation can be subdivided into four
operating states with the engine running and the
high-pressure pump generating pressure:
• Injector closed (with high pressure applied)
• Injector opens (start of injection)
• Injector opened fully
• Injector closes (end of injection)
Injector closed (with high pressure applied)
With the injector closed (at-rest state), the solenoid
valve is not energized and is therefore closed. With
the bleed orifice closed, the valve spring forces the
armature’s ball onto the bleed-orifice seat. The rail’s
high pressure build up in the valve control chamber,
and the same pressure is also present in the nozzle’s
chamber volume. The rail pressure applied at the
control plunger’s end face, together with the force of
the nozzle spring, maintain the nozzle in the closed
position against the opening forces applied to its
pressure stage (Fig. 5).
Injector opens (start of injection)
The solenoid valve is energized with the pickup
current which serves to ensure that it open quickly.
Fig. 4 FUEL INJECTOR
1 - FUEL INJECTOR
2 - NOZZLE
3 - FUEL INLET FITTING
4 - ELECTRICAL CONNECTION
Fig. 5 INJECTOR COMPONENTS
1 - INJECTOR CLOSED (AT-REST STATUS)
2 - ELECTRICAL CONNECTION
3 - TRIGGERING ELEMENT (SOLENOID VALVE)
4 - FUEL INLET (HIGH PRESSURE) FROM THE RAIL
5 - VALVE BALL
6 - BLEED ORIFICE
7 - FEED ORIFICE
8 - VALVE CONTROL CHAMBER
9 - VALVE CONTROL PLUNGER
10 - FEED PASSAGE TO THE NOZZLE
11 - NOZZLE NEEDLE
14a - 4 FUEL INJECTION WG
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