MAINTENANCE MANUAL OF ENGINE
120
4. Fuel supply system
4.1 Theoretical information
System function: The fuel system is mainly
used to deliver the fuel into the high pressure fuel
pump from the fuel tank and via diesel filter and
pipeline with help of the fuel delivery pump, and
then the fuel is pumped from the high pressure
pump, flows through the high pressure fuel pipe,
and is injected to the cylinder by the fuel injector (at
pressure of 21MPa), as well as used for compres-
sion and combustion. The excessive fuel flows back
to the fuel tank via the fuel return pipe of the fuel
injector.
4.2 Fuel injector
Operating principle:
The high pressure fuel pump delivers the high
pressure diesel to the lower end of the needle valve
body through the fuel inlet pipe fitting F and
oblique fuel pipe, and then the diesel is applied to
the pressure-bearing conical surface of the needle
valve. When the pressure exceeds the pre-tightening
force of the high pressure spring D, the needle valve
is raised, the high pressure diesel in the annular fuel
chamber of the needle valve body is atomized and
injected at high speed from the gap formed by the
needle valve and needle valve body. When the fuel
injection pump stops fuel delivery, the pressure in
the annular fuel chamber is reduced, and under ac-
tion of the high pressure spring, the needle valve is
dropped into the valve body to stop fuel injection.
A-Fuel return pipe fitting
B-Injector cap
C-High pressure screw
D-Pressure spring
E-Fuel injector body
F-Fuel inlet pipe fitting
F-Push rod
H-Steel ball
I-Needle valve
J- Fixing thread insert
K-Needle valve body
To Next Page
Loading...
Need help?
General
