12
Group 23 EDC III
Design and operation
Control module
The EDC III system processor is located in the con-
trol module, protected from moisture and vibrations.
The processor continually receives information regar-
ding:
•
Engine speed
•
Charge air pressure
•
Charge air temperature
•
Coolant temperature
•
Oil pressure
•
Oil temperature
•
Fuel alarm, combined alarm for ”water in fuel” and
”fuel pressure”
•
Coolant level
This information is used to make exact determinations
on current operating conditions and allows the proces-
sor to calculate the correct amount of fuel, check the
condition of the engine, etc.
Fuel management
The engine’s fuel need is analyzed up to 100 times
per second (depending on engine speed). The quantity
and timing of fuel injection into the engine are control-
led completely electronically via fuel valves on the
unit injectors.
This means that the engine always receives the cor-
rect amount of fuel under all operating conditions,
providing benefits including improved fuel economy
and minimized exhaust emissions.
The control module checks and controls the unit injec-
tors so that the correct amount of fuel is injected into
each cylinder. It calculates and sets the injection ang-
le. This control is done primarily with the help of the
tachometer sensors and the combined sensor for
charge air pressure/temperature.
The control module actuates the unit injectors via an
electronic signal to the unit injectors’ electromagneti-
cally controlled fuel valve, which can then be opened
or closed.
When the fuel valve is open, fuel streams by, through
the unit injector holes and out through the fuel chan-
nel. Fuel is not injected into the cylinder at this stage.
When the fuel valve is closed, pressure is built up by
the mechanically driven pump piston of the unit injec-
tor. Once enough pressure is built up, fuel is injected
into the cylinder via the injector portion.
The fuel valve is reopened and pressure in the unit in-
jector sinks while fuel injection to the cylinder ceases.
To determine when the fuel valve should be opened or
closed, the control module has access to signals from
sensors and switches.
System description EDC III
EDC III, ”Electronic Diesel Control”, is an electronic system with CAN communication for diesel engine manage-
ment. The system is developed by Volvo Penta and covers fuel management, diagnostic function, etc. The sys-
tem consists of a control module, six unit injectors, a number of sensors that provide information to the control
module, and a data link connector for diagnostics and functionality checks. The EDC III system also has a ”stand
alone” interface that can be linked directly to the engine control module on the engine. The engine can be linked to
a ”CAN” interface and a ”Control Interface Unit” (CIU), which is an interface to the operator area.
Design and operation
