Electronic Control System - Perkins 854E-E34TA Systems Operation Testing And Adjusting

28
Engine Operation
The ECM determines the quantity, timing, and
pressure of the fuel in order to be injected into the fuel
injector.
The ECM uses input from the sensors on the engine.
These sensors include the speed/timing sensors and
the pressure sensors.
The ECM controls the timing and the flow of fuel by
actuating the injector solenoid.
The amount of fuel is injected is a function of fuel
pressure in the fuel manifold and the duration of the
signal to the injector solenoid.
The ECM controls the fuel pressure by increasing or
decreasing the flow of fuel from the fuel injection
pump.
Fuel Injectors
Illustration 23
Typical example
(1) Electrical connections
(2) Bolt
(3) Clamp
(4) Combustion washer
(5) O-ring
(6) Fuel inlet
The fuel injectors contain no serviceable parts apart
from the O-ring seal and the combustion washer. The
clamp and setscrew are serviced separately.
The injector nozzle and control piston volume are
continuously connected to the fuel manifold (rail)
through the high-pressure fuel line. The nozzle
needle is controlled by the control piston, which in
turn is controlled by the pressure in the control piston
volume. The injector contains a solenoid valve that
controls the spill flow from the control piston volume.
The control piston volume has an inlet throttle and an
outlet throttle. The sizing of the throttles determines
the rate of pressure decay in the control volume and
hence the rate of nozzle opening. By opening the
solenoid valve, fuel flows out of the control volume
This document is printed from SPI². Not for RESALE
lowering its internal pressure which allows nozzle
pressure to lift the needle and control piston, this
enables injection to occur.
To end injection, the solenoid valve is closed. Closing
the solenoid valve blocks off the control volume outlet
orifice which causes the control volume pressure to
increase. By increasing control volume pressure, this
forces the control piston, and needle, back down until
the needle reseats in the nozzle. The injection
process ends.
The needle valve has a close fit with the inside of the
nozzle. This makes a positive seal for the valve.
The electronic unit injectors can be instructed to inject
fuel multiple times during the combustion process. A
close pilot injection occurs before the main injection.
The close pilot injection helps to reduce NOx and
noise. The main injection period helps to increase the
torque of the engine. The after injection period helps
to reduce the amount of smoke that is produced.
Fuel Manifold
g02493878
Illustration 24
Typical example
The fuel manifold (2) stores high-pressure fuel from
the fuel injection pump. The high-pressure fuel will
flow to the injectors.
The fuel pressure sensor (3) measures the fuel
pressure in the fuel manifold (2).
The pressure relief valve (1) will prevent the fuel
pressure from getting too high.

Electronic Control System

UENR0623
g02493879
i05241823