User Manual

18 SENR9977
Systems Operation Section
The cam plate moves the distributor plunger toward
the head of the d
istributor (26). The high pressure is
created by a decrease in the volume between the
distributor plunger and the head of the distributor.
The cam plate i
s pressed to the ring by two springs
(28). This brings the distributor plunger back to the
original position. The fuel solenoid valve closes the
high pressur
e volume.
Distribution and Injection
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Illustration 16
The rear view of the Bosch VP30 fuel injection pum p
(29) Fuel so
lenoid valve
(30) Delive
ry valve
(31) Timing
solenoid valve
The distribution of fuel to the injectors takes place
through the
rotating movement of the distributor
plunger. The fuel solenoid valve meters the amount
of fuel by the following operations:
•
Time of closure
•
Duration t
ime
•
Start of injection
•
Amountoffuel
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Illustration 17
Delivery of fuel from the open delivery valve
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Illustration 18
Delivery valv e in the closed position
The delivery valve ensures that the pressure waves
do not allow a reopening of the injector . The pressure
waves are created at the end of the injection process.
The valve cone is lifted by the fuel pressure.
The fuel is forced through the fuel line to the injector.
The delivery ends and the fuel pressure drops. The
valve spring presses the valve cone onto the valve
seat. The reopening of a fuel injector has a negative
effect on emissions.
Timing
Retarding of the fuel injection is the direct relationship
between the start of injection and the position of the
piston. The timing compensates for the higher RPM
of the engine by advancing the start of injection.