Inlet Valve And Delivery Valve; Lubrication And Cooling Of The Hp Pump; Phasing Of Hp Pump Required And Offer 2 Advantages - SSANGYONG 2004 Rexton 2.7XDi Workshop Manual

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.
FUEL SYSTEM
DI ENG SM - 2004.4
<Inlet valve> <Delivery valve>
DI07-19
Y220_07023
CHANGED BY
EFFECTIVE DATE
AFFECTED VIN