Siemens-Common Rail System – High pressure generation and fuel routing in the high pressure pump

A Fuel feed
B Fuel feed (fuel quantity fed to the high pressure pump)
C High pressure connection to the fuel rail
D Fuel return
1 Admission-pressure control valve
2 Screen filter
3 Intake side of transfer pump
4 Transfer pump
5 Fuel metering valve
6 Fuel pressure control valve
7 Fluid filter
8 High pressure pump
9 Eccentric on drive shaft
10 Pump element inlet valve
11 Pump element outlet valve
12 High-pressure ring line
13 High pressure pump elements
14 Lubrication valve

The fuel is drawn from the fuel tank via the fuel filter by means of the transfer pump integrated in the high pressure pump. The transfer pump delivers the fuel on to the fuel metering valve and to the lubrication valve. When the fuel metering valve is closed, the admission pressure control valve opens and routes the excess fuel back to the inlet side of the transfer pump. The lubrication valve is calibrated in order to always ensure sufficient lubrication and cooling in the interior of the pump.

The fuel quantity fed to the high pressure chambers (pump elements) is determined via the electromagnetically operated fuel metering valve (actuated by the PCM). The fuel pressure control valve is located in the high pressure channel, between the high pressure chambers and the high pressure outlet port to the fuel rail. This electro-magnetically operated valve, which is actuated by the PCM controls the fuel pressure which is fed into the fuel rail via the high pressure outlet port. The fuel pressure control valve routes the excess fuel into the fuel return line and back to the fuel tank.

03. September 2018 by Ron
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