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ENGINE FUEL SYSTEM
FUEL PRESSURE REGULATOR/INJECTORS
Fuel Pressure Regulator
Fuel pressure is maintained at a constant level by
means of a pressure regulator. The regulator consists
of a metal casing inside of which a spring-loaded
diaphragm
opens a discharge line whenever the
pressure in the
circuit
exceeds the
regulated
pressure.
The spring chamber is connected by a tube to the
intake manifold.
The difference between the manifold pressure and
the fuel pressure is thereby kept constant, so that the
pressure drop at the injectors is the same under all
load conditions.
Fuel Injectors
r
The electronmagnetically
controlled injector consists,
basically, of a valve body and injector needle with a
magnetic core. The moveable magnetic core is part
of the needle, and the needle is compressed by a
helical spring against the injector body seat. At the
rear, the injector body has a magnetic winding;
in
front, it has a guide for the injector needle.
1 - Fuel line
2 - Fuel tank return line
3 - Valve carrier
4 - Diaphragm
5 - Spring
6 - Intake manifold connector
7 - Valve
1 - Injector needle
2 - Magnetic core
3 - Magnetic winding
4 - Electrical connection
5 - Filter
4
Each cylinder has one injector located in the intake
tube, which atomizes the fuel ahead of the intake
valve.
Signals from the control unit create a magnetic field
in the winding; the core is attracted and the injector
needle is pulled away from its seat. The passage for
the fuel under pressure is now open. Core travel is
about 0.15 mm (about 0.006 in.). Opening time is
determined by the control unit depending on engine ~
operating conditions at the time.
.-
This method of injection has the advantage of not
only requiring
low injection
pressure but also of
allowing
group
injection,
which
simplifies
the
technical construction of the system.
C2-3
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