Start Of Injection; End Of Injection - SSANGYONG 2004 Rexton 2.7XDi Workshop Manual

Start of injection

As soon as Ff < Fo, or in other words:
P < P * A/S
control rail
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 -
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.
FUEL SYSTEM
DI ENG SM - 2004.4
P) * S
DI07-51
CHANGED BY
EFFECTIVE DATE
AFFECTED VIN