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SsangYong Rexton. Manual - part 83

DI07-48

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

Y220_07100

INJECTOR

The C21 labels including injector characteristics are attached in each injector. These C21 values should be input to ECU
by using Scan-i when replacing the ECU or injectors.

Special cautions:

1. Plug the openings of hoses and pipes with the sealing caps.

2. Replace the copper washer with new one plus injector holder bolt & washer.

3. Tighten the injector holder bolts with the specified tightening torque.

4. Be careful not to drop the injector.

Specifications

Length:

· Injector body 181.35 mm

· Injector nozzle 22.155 mm

Nozzle basic:

5 Holes, 146°C Cone Angle,

840 mm

/min

Control: PWM type (solenoid injector)

Tightening: Clamping by fork

Fuel return: Nipple

C2I label

C2I value

Cap nut

Washer

Nozzle needle

Nozzle body

Adaptor plate

Control valve

Bobbin

Nozzle holder body

Leak off nipple

Edge filter

DI07-49

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

The maximum injection pressures are approximately 1,600 bar. The forces to be overcome in order to lift the needle of
the injector are therefore very large. Because of this, it is impossible to directly control the injector by using an electro-
magnetic actuator, unless very high currents are used, which would be incompatible with the reaction times required for
the multiple injections. The injector is therefore indirectly controlled by means of a valve controlling the pressurizing or
discharging of the control chamber located above the needle:

• When the needle is required to lift (at the start of injection): the valve is opened in order to discharge the control

chamber into the back leak circuit.

• When the needle has to close (at the end of injection): the valve closes again so that pressure is re-established in

the control chamber.

Valve

In order to guarantee response time and minimum energy
consumption:

• The valve must be as light as possible.

• The valve stroke must be as short as possible.

• The effort needed to move the valve must be minimal, which

means that the valve must be in hydraulic equilibrium in
the closed position.

Spring pressure ensures contact between the valve and its
seat. To lift the valve, it is therefore required to overcome the
force being applied by this spring.

Y220_07102

INO inlet

irifice

NOP nozzle

path orifice

SPO spill
orifice

Control
chamber

Spacer

Y220_07101

Valve

Volume

under

high

pressure

Valve

Spill

orifice

Contact
making seal

Depressuriza-
tion grooves

Volume under
vacuum

Spacer

The spacer is situated underneath the valve support. It inte-
grates the control chamber and the three calibrated orifice
which allow operation of the injector. These orifices are:

• The injector supply orifice (Nozzle Path Orifice: NPO)

• The control chamber discharge orifice (Spill Orifice: SPO)

• The control chamber filling orifice (Inlet Orifice: INO)

DI07-50

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

Ff =
(Ff = Prail S)

Fo =
(Fo = Prail A)

Y220_07103

Principle of Operation

Injector at rest

The valve is closed. The control chamber is subject to the rail
pressure.

The pressure force applied by the fuel onto the needle is:

Ff = S * P

rail

The needle is closed and hence there is no fluid circulation
through the NPO orifice. While static, the nozzle produces no
pressure drop. The cone of the needle is therefore subject to
the rail pressure. The force applied by the fuel to the needle is:

Fo = A * P

rail

Since Ff > Fo, the needle is held in the closed position. There
is no injection.

Solenoid valve control

When the solenoid valve is energized, the valve opens. The
fuel contained in the control chamber is expelled through the
discharge orifice known as the Spill Orifice (SPO).

As soon as Ff > Fo, the needle remains held against its seat
and there is no injection.

Y220_07104

Ff = pressure

space

(Ff = P

rail

Fo = pressure

space

(Fo = P

rail

Valve closed

Needle closed

No injection

Valve opens

Needle closed

No injection

Valve open

Needle opens

Start of injection

Valve closes

Needle open

End of injection

Valve closed

Needle closed

No injection

* S: The area of the flat upper surface of the injector’s needle

* A: The area of the needle surface situated above the section

of contact between the needle and its seat

* Ff: The force applied by the fuel onto section “S”

* Fo:The force applied by the fuel onto section “A”

DI07-51

CHANGED BY

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FUEL SYSTEM

DI ENG SM - 2004.4

Start of injection

As soon as Ff < Fo, or in other words:

control

< P

rail

* A/S

The needle lifts and injection begins. As long as the valve is open, the injector’s needle remains lifted. When injection
begins, fuel circulation is established to feed the injector. The passage of the fuel through the inlet orifice of the injector
(similar to a nozzle) leads to a pressure drop which depends on the rail pressure.

When the rail pressure is at its highest (1600 bar), this pressure drop exceeds 100 bar. The pressure applied to the cone
of the needle (the injection pressure) is therefore lower than the rail pressure.

End of injection

As soon as the solenoid valve is de-energized, the valve closes and the control chamber is filled. Since the needle is
open, the thrust section areas situated on either side of the needle is therefore to apply different pressures to each of
these faces. The pressure in the control chamber cannot exceed the rail pressure, so it is therefore necessary to limit
the pressure applied to the needle’s cone. This pressure limitation is achieved by the NPO orifice which produces a
pressure drop when fuel is passing through it.

Prail * S (Prail - P) * S

When static, this pressure drop is zero. When the pressure in the control chamber becomes higher than the pressure
applied to the needle’s cone, the injection stops.

Content .. 81 82 83 84 ..