PRINCIPLES GASOLINE/DIESEL FURL SYSTEMS - OD1620 - LESSON 2/TASK 2
FIGURE 48. FUEL METERING SYSTEM.
(4) Injectors (figure 49 on the following page). The injector
consists of a forged body with a properly fitted plunger. This plunger is
forced down by the engine camshaft against spring action through a rocker
arm and push rod. A fuel cup is mounted on the end of the body, combined
with a holetype nozzle.
(a) The fuel metering pump forces a precisely measured fuel charge
into the cup on the intake stroke of the engine. The quantity of the fuel
charge is based on the speed and load requirements of the engine. The
operation of this system depends on the injector delivery line being full of
fuel. It will then follow naturally that any fuel added by the fuel
metering pump will expel an equal amount of fuel into the injector.
(b) The fuel lies in the cup during the compression stroke of the
engine, and the compressed air is forced through the small spray holes in
the cup. The fuel in the tip of the cup is exposed to the intense heat of
compression. The air rushing in through the holes in the nozzle tip serves
to break the fuel charge into droplets.
82
Previous Page
