Bosch-Common Rail System – High pressure pump
High pressure pump CP3.2
1 Transfer pump
2 Fuel metering valve
3 Pump plunger
5 Drive shaft
6 Pump housing
High pressure pump CP1H
1 Fuel metering valve
2 Fuel return port
3 Fuel supply port
4 Transfer pump
5 High pressure port (to fuel rail)
Two different types of high pressure pumps are used in the Delphi common rail system:
• High pressure pump CP3.2 and
• High pressure pump CP1H
With the launch of the Focus C-MAX 2003.75 (06/2003-), initially only the CP3.2 was installed. Over time the CP3.2 was being replaced increasingly by the CP1H and this pump was installed from the outset for certain new launches.
The following table shows the fuel injection timing of the CP1H based on the vehicle.
The function of the high pressure pump CP1H is essentially the same as that of the CP3.2.
Function of the high-pressure pump
First, the fuel is drawn from the tank by the transfer pump mounted on the high-pressure pump and delivered to the high-pressure pump.
The high-pressure pump provides the interface between the low and the high pressure systems. Its function is to always provide sufficient compressed fuel under all operating conditions and for the entire service life of the vehicle.
The high-pressure pump permanently generates the high system pressure for the fuel rail. Therefore, the compressed fuel does not have to be supplied under high pressure for each injection process individually, unlike systems with distributor type injection pumps. Due to the permanently high system pressure, injection quality is optimized over the entire engine speed/load range.