ECD SYSTEM


  1. FUNCTION


    1. The ECM calculates the target injection pressure (30 to 160 MPa) based on the final injection volume and signals from the crank position sensor.

    2. To control fuel pressure, signals sent to the metering unit of the supply pump regulate the pumping volume and signals sent to the fuel pressure regulator of the common-rail regulate the discharge volume, so that the pressure detected by the fuel pressure sensor matches the target injection pressure.

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      Metering Unit Control The ECM controls the metering unit opening in order to regulate the fuel volume that is pumped by the supply pump to the common-rail. Consequently, the fuel pressure in the common-rail is controlled to the target injection pressure.
      Metering Unit Opening Small When the metering unit opening is small, the fuel suction area is kept small, which decreases the transferable fuel quantity.
      The plunger strokes fully, however, the suction volume becomes small due to the small suction area.
      Pumping will start at the time when the fuel pressure has become higher than the common-rail pressure.
      Metering Unit Opening Large When the metering unit opening is large, the fuel suction area is kept large, which increases the transferable fuel quantity.
      The plunger strokes fully, the suction volume will increase because the suction area is large.
      Pumping will start at the time when the fuel pressure has become higher than the common-rail pressure.
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      A00XRDFE06