SsangYong Stavic / SsangYong Rodius (2005 year). Manual - part 132

DI07-19

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FUEL SYSTEM

DI ENG SM - 2004.9

INLET METERING VALVE (IMV)

Overview

The LP actuator, also called the inlet metering valve, is used
to control the rail pressure by regulating the amount of fuel
which is sent to the pumping element of the HP pump.

This actuator has two purposes:

1. Firstly, it allows the efficiency of the injection system to

be improved, since the HP pump only compresses the
amount of fuel necessary to maintain in the rail the level
of pressure required by the system as a function of the
engine’s operating conditions.

2. Secondary, it allows the temperature to be reduced in

the fuel tank. When the excess fuel is discharged into
the back leak circuit, the pressure reduction in the fluid
(from rail pressure down to atmospheric pressure) gives
off a large amount of heat. This leads to a temperature
rise in the fuel entering the tank. In order to prevent too
high a temperature being reached, it is necessary to limit
the amount of heat generated by the fuel pressure
reduction, by reducing the back leak flow. To reduce the
back leak flow, it is sufficient to adapt the flow of the HP
pump to the engine’s requirements throughout its
operating range.

IMV effect

without IMV
with IMV

without IMV
with IMV

Fuel temperature at

system backleak

Fuel T

emp.(°C

)

Torque (Nm)

Torque (Nm)

Rail pressure = 80 bar

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FUEL SYSTEM

DI ENG SM - 2004.9

Composition of IMV

The IMV is located on the hydraulic head of the pump. It is fed with fuel by the transfer pump via two radial holes. A
cylindrical filter is fitted over the feed orifices of the IMV. This makes it possible to protect not only the LP actuator, but
also all the components of the injection system located downstream of the IMV.

The IMV consists of the following components:

• A piston held in the fully open position by a spring.

• A piston filter located at inlet.

• Two O-rings ensuring pressure tightness between the hydraulic head and the body of the IMV.

• A body provided with two radial inlet holes and an axial outlet hole.

• Coil

Filter

High pressure

Outlet hole

O-ring

Fuel

Transfer pump

Transfer pump

Solenoid

Fuel

Spring

Piston

DI07-21

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FUEL SYSTEM

DI ENG SM - 2004.9

Principle of Operation

The LP actuator is used to proportion the amount of fuel sent to the pumping element of the HP pump in such a way that
the pressure measured by the HP sensor is equal to the pressure demand sent out by the ECU. At each point of
operation, it is necessary to have:

• Flow introduced into the HP pump = Injected flow + Injector backleak flow + injector control flow

The IMV is normally open when it is not being supplied with fuel. It cannot therefore be used as a safety device to shut
down the engine if required.

The IMV is controlled by current. The flow/current law is represented below.

• Engine speed

• Flow demand

• Rail pressure demand

• Measured rail pressure

E

C

U

• Inlet Metering

Valve (IMV)

Piston stroke

Diameter of holes

Coil resistance

Power supply

Max. current

Weight

Operating temperature

Fluid temperature

Control logic

1.4 mm

3.4 mm

5.4 

Ω (at 25°C)

Battery voltage (It is prohibited to supply the IMV directly at the battery voltage
during the diagnostic test)

1 A

260 g

40°C < T < 125°C

40°C < T < 90°C

Normally open without power (The flow decreases as the current rises).

• ECU determines the value of the current to be sent to the IMV according to:

Specifications

Flow (I/hr)

Flow / Current Law

Current (mA)

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FUEL SYSTEM

DI ENG SM - 2004.9

HIGH FUEL PRESSURE LINE

High Pressure Pump

Description

This pump generates high fuel pressure and is driven by timing chain (radial plunger principle). This pump pressurizes
the fuel to approx. 1600 bar and sends this high pressurized fuel to high pressure accumulator (common rail) via high
pressure line.

It is possible to extend the pumping phase in order to considerably reduce drive torque, vibration and noise since the pump no
longer determines the injection period. The differences from conventional rotary pumps lies in the fact that it is no longer the
hydraulic head rotor which turns inside the cam, but the cam which turns around the hydraulic head. Thus, any problems of
dynamic pressure tightness are eliminated because the high pressure is generated in the fixed part of the pump.

Specifications

• Maximum operating pressure: 1600 

±

 150 bar

• Max. Overpressure: 2100 bar

• Maximum sealing pressure: when using a plug instead of PRV, no leaks around pump outlet port (when applying

2500 bar of constant pressure)

• Operating temperature: Continuously operating within temperature range of -30°C  ~ 120°C in engine compartment

• Inflowing fuel temperature: The maximum inflowing fuel temperature is 85°C (continuously able to operate)

• Pump inlet pressure: Relative pressure Min. - 0.48 bar (to end of filter’s lifetime)

• Driving torque: 15 Nm / 1600 bar

• Gear ratio (engine: pump): 0.625

• Lubrication:

- Inside lubrication (rear bearing): Fuel

- Outside lubrication (front bearing): Engine oil

1. IMV (Inlet Metering Valve)

2. Hydraulic Head

3. Plunger

4. Drive shaft and cam ring

5. Housing

6. Roller and shoe

7. Transfer pump

8. Fuel temperature sensor

9. High fuel pressure - OUT

10. Pressure regulator

Fuel supply

Fuel
discharge