Chapter 3 Fuel Injection Equipment
5. Injection Pump Construction and Operation
, 4LHA Serit
Regulating
Valve
Fuel
inlet
Regulating
valve
Spring
Piston
Feed
pump
outlet port
Feed
pump fuel oil delivery pressure increases
proportionately
with
an increase in injection
pump
speed.
However,
the total fuel oil injection quantity
necessary
for the engine is considerably
less
than
that
delivered by the feed pump. There-
fore, in order to prevent an excessive increase
in the pump chamber pressure caused by the
excess
fuel oil, and to adjust the pump cham-
ber
pressure so
that
it is usually within the
spe-
cified
limit,
a regulating valve is installed near
the feed pump outlet. The timer performs tim-
ing control using the pump chamber pressure,
which is regulated by the regulating valve.
Fig.
8 Regulating valve operation
3-1-9
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