SsangYong Rexton. Service manual - part 85

DI07-56

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

Y220_07109

It pushes the nozzle needle and
the control chamber opens (12)

The nozzle closes (13)

DI07-57

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

Y220_07110

• Small injection separation: min. 200

(duration between the end of pilot injection and start of
main injection)

• Opening Delay

 : Delayed time from applying operating voltage to start of

injection

• Adjustment of feedback injection volume: C2I

Fuel pressure

Fuel pressure

• Minimum operating pressure: start injection over 100 bar

• Maximum operating pressure: 1,600 bar (max. operating pressure in normal conditions)

• Max overpressure: 2,100 bar

Maximum fuel volume at each injector cycle

• Pilot Injection 

 5 mm

3

• Main Injection 

 85 mm

3

 (within 200 ~ 1,600 bar)

Y220_07111

Pilot injection

Main injection

Small injection separation

Opening delay definition

Injection rate

Injector drive pulse

Time (

)

10%

signal

amplitude

10%

signal

amplitude

DI07-58

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

Y220_07112

Injector control

The control current of the coil takes the following form:

The low current allows the Joule effect losses in the ECU and injector to be reduced. The call current is higher than the
hold current because during the hold phase.

• The air gap between the valve and the coil is reduced and the electromagnetic force to be applied to the valve can

thus be reduced. It is no longer necessary to overcome the valve inertia.

Note

Joule Effect: The principle that the heat produced by an electric current is equal to the product of the resistance

of the conductor, the square of the current, and the time for which it flows.

I: current (A)

R: resistance (

Ω

Ω

Ω

Ω

Ω)

T: time (sec)

H: calori (cal)

Heat capacity (H) = 0.24 I 

2

RT

Time

Hold period

Pull-in period

Through pull

current = 7.5 A

Current

Peak pull current

= 22.0 A

Through hold current

= 7.5 A

Peak hold current

= 22.0 A

DI07-59

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

FUEL SYSTEM

DI ENG SM - 2004.4

Y220_07113

Y220_07114

<Characteristic curve of discharge without pilot injection>

<Characteristic curve of discharge with pilot injection>

Fuel Injection

Other than conventional diesel engine, common diesel engine use two steps injection as follows:

• Pilot Injection

• Main  Injection

In above two step injection, the fuel injection volume and injection timing is calibrated according to fuel pressure and fuel
temperature.

Pilot injection

Before starting main injection, a small amount of fuel is injected to help proper combustion. This injection is for reducing
the engine noise and vibration.

In other words, it makes the pressure increase in combustion chamber during combustion smooth to reduce the engine
noise and vibration (suppressing the surging). Basic values for pilot injection are adjusted according to the coolant
temperature and intake air pressure.

Main injection

Actual output from engine is achieved by main injection.

The main injection determines the pilot injection has been occurred, then calculates the injection volume. Accelerator
pedal sensor, engine rpm, coolant temperature, intake air temperature and atmospheric pressure are basic date to
calculate the fuel injection volume in main injection.

1. Pilot injection

2. Main injection

1a. Ignition pressure with pilot injection

2a. Ignition pressure without pilot injection

<Characteristic curve of combustion chamber pressure during pilot injection>

Needle lift (k)

Angle of crankshaft

Cylinder pressure (p)

Needle lift (k)

Cylinder pressure (p)

Angle of crankshaft

Angle of crankshaft

Pressure