Engine Mechanics
36
Pump-Injector Units
The same type pump-injector units used in the
1.9l/74 kW TDI engine are also used in the
V10-TDI engine.
They are characterized by:
•
A low-friction drive
•
An increased injection pressure in the
partial load range
•
A compact solenoid valve
To provide a low-friction drive, the adjusting
screw is equipped with a rounded end while the
stud is provided with a ball socket. Due to the
large radius, the surface pressure is low. In
addition, the engine oil can collect in the ball
socket, thus ensuring good lubrication between
the adjusting screw and the stud.
In the partial load range, the injection pressure
is increased by an alternative piston with a large
stroke. Due to the large stroke of the alternative
piston and the throttling effect of the inlet port
between the jet spring space and the fuel
channel, the pressure in the jet spring space
increases. The jet springs are further
prestressed, thus increasing the injection
pressure.
303_010
Adjusting Screw
Stud
Solenoid
Valve
Alternative
Piston
Inlet Port
Jet Spring
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