F i g u r e 11C-3. C u t a w a y View of Fuel
Injector
Figure 11C-5 on page 11C-3 illustrates
the phases of injector operation by the
vertical travel of the injector plunger.
The continuous fuel flow through the in-
j e c t o r serves i n a d d i t i o n t o p r e v e n t i n g
a i r pockets in the fuel system, as a cool-
ant for those injector parts subjected to
Figure 11C-2. F u e l I n j e c t o r A s s e m b l y
high combustion temperatures.
3. Atomizes the fuel for mixing with the
To vary the power output of the engine,
air in the combustion chamber.
injectors having different fuel output ca-
The fuel output of
pacities are used.
4. Permits continuous fuel flow.
the various injectors is governed by the
helix angle of the plunger and the type
of spray tip used. Refer to
Combustion required for satisfactory en-
Figure 11C-6 on page 11C-4 for the iden-
gine operation is obtained by injecting,
of t h e i n j e c t o r s a n d t h e i r
tification
under pressure, a small quantity of ac-
respective plungers and spray tips.
curately metered and finely atomized fuel
oil into the cylinder.
Since the helix angle on the plunger de-
termines the output and operating char-
Metering of the fuel is accomplished by
acteristics of a particular injector, it is
an upper and lower helix machined in the
imperative that the correct injector be
lower end of the injector plunger.
If injectors of dif-
used in the engine.
page
11C-3
illustrates
ferent types are mixed, erratic operation
metering from no-load to
fuel
the
will result and may cause serious damage
full-load by rotating of the plunger in
t o the engine or to the machine.
the bushing.