SsangYong Rexton. Manual - part 75

DI07-16

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

Y220_07020

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)

DI07-17

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AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

Y220_07021

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

DI07-18

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AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

<Pressurize>

Y220_07022

Principle of operation

• During the filling phase, the rollers are kept in contact with the cam by means of coil springs mounted on either side

of each shoe. The transfer pressure is sufficient to open the inlet valve and to move the pumping plungers apart.
Thus, the dead volume between the two plungers fills with fuel.

• When the diametrically opposite rollers simultaneously encounter the leading edge of the cam, the plungers are

pushed towards each other.

• As soon as the pressure becomes higher than the transfer pressure, the inlet valve closes. When the pressure

becomes higher than the pressure inside the rail, the delivery valve opens. Consequently, the fuel is pumped under
pressure into the rail.

• During the input phase, transfer pressure pushes back the inlet valve. Fuel enters the body of the pumping element.

The valve closes as soon as the pressure in the pumping element becomes higher than the transfer pressure.

• During the input phase, the ball of the delivery valve is subject to the rail pressure on its outer face and to the transfer

pressure on its inner face. Thus the ball rests on its seat, ensuring the pressure tightness of the body of the pumping
element. When the pressure in the element becomes higher than the pressure in the rail, the ball is unbalanced and
it opens. Fuel is then pumped into the rail at high pressure.

This high pressure pump generates the driving torque with low peak torque to maintain the stress to driving components.
This torque is smaller than that of conventional injection pump, thus, only a small load will be applied to pump. The
required power to drive pump is determined by set pressure for rail and pump speed (delivery flow). Note that the fuel
leakage or defective pressure control valve may affect the engine output.

<Fuel input>

Roller

Plunger

DI07-19

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AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

<Inlet valve>

<Delivery valve>

Y220_07023

Inlet valve and delivery valve

During the input phase, transfer pressure pushes back the inlet valve. Fuel enters the body of the pumping element.
Under the effect of the transfer pressure, the two plungers are forced apart. When the rollers simultaneously encounter
the leading edge of the cam, pressure suddenly rises in the body. Of the pumping element. The valve closes as soon as
the pressure in the pumping element becomes higher than the transfer pressure. During the input phase, the ball of the
delivery valve is subject to the rail pressure on its outer face and to the transfer pressure on its inner face. Thus the ball
rests on its seat, ensuring the pressure tightness of the body of the pumping element. When the two diametrically
opposite rollers encounter the leading edges of the cam, the plungers are forced together and pressure quickly rises in
the body of the pumping element. When the pressure in the element becomes higher than the pressure in the rail, the
ball is unbalanced and it opens. The spring calibration is negligible compared with the pressure forces. Fuel is then
pumped into the rail at high pressure.

Lubrication and cooling of the HP pump

Lubrication and cooling of the pump are provided by the fuel circulation. The minimum flow required to ensure adequate
operation of the pump is 50  /h.

Phasing of HP pump required and offer 2 advantages

Conventional fuel injection pumps ensure pressurizing and distribution of the fuel to the different injectors. It is essential
to set the pump in such a way that the injection occurs at the required place during the cycle. The HP pump of the
common rail system is no longer used for the fuel distribution, it is therefore not necessary to set the pump in relation
to the engine.

Nevertheless, the setting or phasing of the pump offers two advantages:

• It allows the torque variations of the camshaft and the pump to be synchronized in order to reduce the stresses on

the timing belt.

• It allows pressure control to be improved by synchronizing peak pressures produced by the pump with pressure-

drops caused by each injection.

This phasing allows pressure stability to be improved, which helps to reduce the difference in flow between the cylinders.