Engine Iveco Vector 8. Manual — part 8

Figure 14

The pumping element (5) is oriented on the cam on the pump shaft.

In the suction phase, the pumping element is fed through the supply line (3). The amount of fuel to send to the pumping element
is decided by the pressure regulator (7).

Depending on the command received from the control unit, the pressure regulator will control the flow of fuel to the pumping
element. During the compression phase of the pumping element, the fuel pressure opens the common rail delivery valve (2),
before going out the outlet (1).

The pump shaft supports are lubricated through the ducts (oil channels) (8).

The pressure regulator (7) decides the amount of fuel with which to supply the pumping elements; any excess fuel flows out
through the duct (9).

The pressure relief valve (10), has the function of keeping a constant inlet pressure at 5 bar for the pressure regulator.

High pressure regulator
Located at the high—pressure pump inlet, on the low—pressure system, it controls the flow of fuel to the high—pressure pump
according to the commands received from the electronic control unit (ECU).

If there is no command signal, the pressure regulator is normally open, so the high—pressure pump is in the condition of maximum
delivery.

The control unit sends the regulator a command signal to control the fuel flow to the high—pressure pump.

1. Electrical connector — 2. Fuel outlet — 3. Fuel inlet

SECTION 2 - FUEL

17

VECTOR 8 ENGINES

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Base - April 2006

Figure 15

Pressure relief valve 5 bar
Mounted in parallel with the pressure regulator, its function is to keep the pressure at the regulator inlet constant, which is
necessary for the system to work properly.

When the pressure at the inlet of the regulator exceeds 5 bar, the relief cylinder (8, Figure 16), will begin to open in order to
lead the additional fuel to the outlet.

Depending on the fuel flow required, with the pressure regulator partially closed, the cylinder moves into a dynamically balanced
position such as to ensure a constant pressure of 5 bar at the regulator inlet.

18

SECTION 2 - FUEL

VECTOR 8 ENGINES

Base - April 2006

Print P2D32V001E

Figure 16

Pressure regulator and 5 bar pressure relief valve at max. fuel delivery

1. Coil — 2. Core — 3. Pre—loading spring — 4. Shutter — 5. High—pressure pump supply — 6. Fuel inlet (from the filter) — 7. Fuel

return from the high—pressure pump — 8. Cylinder for opening outlet line — 9. Fuel outlet — 10. Fuel delivery

When the coil (1) of the regulator is not energised, the core (2) is in the rest position due to the pre—loading spring (3). The
shutter (4) is in the position of maximum delivery and the HPP will provide the rail with max. pressure.

The clearance between the internal parts in the high pressure pump permits fuel leakage, which is used to lubricate the pump.
This excess fuel is sent towards the pressure relief valve.

The cylinder (8) in the pressure relief valve will then move into a balanced position and there it will maintain the pressure in the
low pressure line at 5 bar.

81386

SECTION 2 - FUEL

19

VECTOR 8 ENGINES

Print P2D32V001E

Base - April 2006

Figure 17

Pressure regulator and 5 bar pressure relief valve in regulation mode

1. Coil — 2. Core — 3. Pre—loading spring — 4. Shutter — 5. High—pressure pump supply — 6. Fuel inlet (from the filter) — 7. Fuel

return from the high—pressure pump — 8. Cylinder for opening outlet line — 9. Fuel outlet — 10. Fuel delivery

When the PWM is in regulation mode the coil (1) is energised (between 0—1600mA depending on the pressure required by
the ECM) and the core (2) is moving the shutter (4) towards the closing position in order to limit the fuel flow to the HPP and
thereby reducing the fuel pressure in the rail.

The cylinder (8) in the pressure relief valve will move into a balance position and there it will maintain the pressure in the low
pressure line at 5 bar.

81387

20

SECTION 2 - FUEL

VECTOR 8 ENGINES

Base - April 2006

Print P2D32V001E