DV11
Operation and Maintenance
119
Common Rail Fuel-injection System
Printed in Mar. 2005 PS-MMA0608-E1A
3.4.8. Fuel filter
z Fuel filter inadequate filtering can lead to damage at the pump components,
delivery valves, and injector nozzles. The fuel filter cleans the fuel before it
reaches the high pressure pump, and thereby prevents premature wear at the
pump's sensitive components.
3.4.9. High pressure fuel delivery
z The high pressure stage of the fuel system in a common rail installation
comprises.
- High pressure pump with pressure control valve
- High pressure fuel lines
- The common rail as the high pressure accumulator
- Rail pressure sensor.
- Pressure limiting valve.
- Injectors
- Fuel return lines
3.4.10. High pressure system components
z Fuel high pressure pump
The high-pressure pump pressurizes the fuel to a system pressure of up to
1,600bar. This pressurized fuel then passes through a high-pressure line and into
the tubular high pressure fuel accumulator (common rail).
z Common rail
Even after an injector has taken fuel from the common rail in order to inject it, the
fuel pressure inside the rail remains practically constant. Fuel pressure is
measured by the rail pressure sensor and maintained at the desired level by the
pressure control valve. It is the job of the pressure limiter valve to limit the fuel
pressure in the rail to maximum 1,600 bar.
z Injector
The nozzles of these injectors open when the solenoid valve is triggered and
permit the flow of fuel. They inject the fuel directly into the engine's combustion
chamber, The excess fuel which was needed for opening the injector nozzles
flows back to the tank through a collector line. The return fuel from the pressure
control valve and from the low pressure stage is also led into this collector line
together with the fuel used to lubricate the high pressure pump.
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