CONSTRUCTION
The supply pump (injection or supply pump assembly) consists of an inner cam (eccentric camshaft), an outer cam (polygon ring), 3 plungers, a metering unit and a gear pump. Each plunger is placed outside of the outer cam.
The gear pump pumps fuel to the 3 plungers.
A metering unit controls the volume of fuel drawn into the plungers.
The inner cam drives the outer cam.
The outer cam drives the 3 plungers.
The plungers pressurize the fuel.
| *1 | Gear Pump | *2 | Outer Cam |
| *3 | Plunger | *4 | Inner Cam |
| *5 | Metering Unit | - | - |
OPERATION
Due to the rotation of the inner cam (eccentric camshaft), the outer cam pushes plunger "A" upward as illustrated below. The force of the spring pulls plunger "B". As a result, plunger "B" draws fuel in, and plunger "A" pumps fuel at the same time.
| *1 | Metering Unit | *2 | Plunger A |
| *3 | Plunger B | *4 | Plunger C |
| *a | Suction | *b | to Common-rail |
| *c | Pumping Finish | *d | Pumping Start |