Supply Pump Overall Fuel Flow
• The fuel is suctioned by the feed pump from the fuel tank and sent to the SCV. At this time, the regulating valve adjusts the fuel pressure to below a certain level. The fuel sent from the feed pump has the required discharge quantity adjusted by the SCV, and enters the pump unit through the suction valve. The fuel pumped by the pump unit is pumped through the delivery valve to the rail.
Operation
• The discharge quantity is controlled by SCV control, the same as for the HP2, however it differs from the HP2 in that the valve opening is adjusted by duty ratio control.
• In the intake stroke, the spring makes the plunger follow the movement of the ring cam, so the plunger descends together with the ring cam. Thus, unlike the HP2, the plunger itself also suctions in fuel. When the suctioned fuel passes through the SCV, the flow quantity is controlled to the required discharge quantity by the valve opening and enters the pump main unit.
• The quantity of fuel adjusted by the SCV is pumped during the pumping stroke.
