DV11
Operation and Maintenance
122
Common Rail Fuel-injection System
Printed in Mar. 2005 PS-MMA0608-E1A
5) Fuel metering shut off valve
When one of the pumping
elements is switched off, this leads
to a reduction of the amount of fuel
which is pumped into the common
rail. Switch off involves the suction
valve remaining open permanently.
When the solenoid valve of the
pumping-element switch off is
triggered, a pin attached to its
armature continually holds the inlet valve open. The result is that the fuel drawn
into this pumping element cannot be compressed during the delivery stroke. No
pressure is generated in the element chamber since the fuel flows back into the
low-pressure passage again. With one of its pumping elements switched off when
less power is needed, the high-pressure pump no longer delivers the fuel
continuously but rather with brief interruptions in delivery.
6) Common rail
The common rail stores the fuel at high pressure. At the same time, the pressure
oscillations which are generated due to the high pressure pump delivery and the
injection of fuel are damped by the rail volume. After the injector use the fuel from
the common rail for fuel injection, the pressure oscillation of the common rail is
maintained constantly by the common rail volume. The fuel pressure is calculated
by the pressure sensor of the common rail, is maintained with required value by
the pressure control valve. The fuel pressure is controlled at max. 1,600 bar in the
common rail.
Fuel metering
shut off switch
To Next Page
Loading...
Need help?
General
