01-10-20 Fuel System Description
General:
The AE 300 is equipped with a common rail fuel injection system. In such a system the common rail is
a high-pressure fuel reservoir that supplies fuel to solenoid type injectors. Fuel enters the common rail
directly from the high-pressure pump which compresses the fuel up to 1600 bar. The amount of
required fuel is regulated by a fuel metering unit which is attached direct to the high pressure pump.
The actual fuel pressure in the rail (and therefore to the injectors) is measured by the rail pressure
sensor. The EECU interprets the rail pressure, compares it to a target value, and adjust the rail
pressure control valve to reach the correct pressure. Return fuel flows back to the fuel tank. Fuel is
supplied to the injectors through the injector supply ports. Excess fuel (not depicted) is also returned.
The fuel pressure supplied to the injectors is varied continuously. A higher fuel pressure ensures
better vaporization and therefore better combustion, as well as shorter injection duration, allowing
delivering the desired fuel volume at the optimal time. By varying the fuel pressure, the injection
duration can be varied for a given desired fuel injection volume per cycle, allowing for better
combustion at lower RPM.
Fig. 01 - 10 Common Rail fuel System
Rail Pressure Control Valve