SsangYong Stavic / SsangYong Rodius (2005 year). Manual - part 133

DI07-23

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FUEL SYSTEM

DI ENG SM - 2004.9

<Pressurize>

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

DI07-24

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FUEL SYSTEM

DI ENG SM - 2004.9

<Inlet valve>

<Delivery valve>

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.

DI07-25

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AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.9

HP Pump Fuel Route

The fuel passed through the fuel filter is sent to the transfer pump via the HP inlet pump. this fuel passes through the
transfer pump by the transferring pressure and maintains the predefined value by the regulating valve in HP pump.

Also, this fuel gets into the IMV that controls only the fuel to the high pressure pump.

The below figure describes the pump operations when acceleration and deceleration.

When need high fuel pressure (acceleration)

Transfer  pump

High pressure pump

IMV open

Venturi

to common rail

to fuel tank

Backleak

Fuel supply

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FUEL SYSTEM

DI ENG SM - 2004.9

<Pressure curve of HP pump>

When do not need high fuel pressure (deceleration)

The fuel is sent to the high pressure side (hydraulic head) and compressed by the plunger. And, goes into the common
rail through the high pressure pipe.

The IMV installed in the high pressure side (hydraulic head) of HP pump precisely controls the fuel amount and delivers
the rail pressure feedback same as required amount.

The IMV is controlled by ECU.

Performance curve of HP pump

The time required to obtain a sufficient pressure in the rail to enable the engine to start depends on the volume of the
system (definition of the rail, length of the pipes, etc.). The aim is to reach a pressure of 200 bars in 1.5 revolutions (3rd
compression).

• Maximum operating pressure: 1600 

±

 150 bar

IMV close

Venturi

to common rail

to fuel tank

Backleak

Fuel supply

Transfer  pump

High pressure pump

Rail pressure (bar)

Engine speed (rpm)