Functional description

As soon as the engine is running, the triple cam continuously moves the piston to make its stroke. Fuel is thus pressurized for as long as new fuel is delivered into the high pressure pump via the quantity control valve. The quantity control valve is activated by the engine control system; it specifies the delivered volume of fuel. Pressure regulation takes place via the quantity control valve in that it is opened or closed by the pump element towards the fuel feed. In the induction stroke, the fuel is sucked in via the opened quantity control valve and delivered back again in the compression stroke into the feed until the quantity control valve closes. The closing time initiates the actual delivery stroke and determines the volume of fuel that is pumped through the non-return valve into the high pressure line.

Fig 1: High Pressure Pump, Volume Control Valve And Fuel Delivery Line

Courtesy of BMW OF NORTH AMERICA, INC.

The quantity control valve controls the fuel pressure in the rail. In addition, the pressure limiting valve provides the possibility to reduce the pressure in the rail. Here, the fuel is fed out of the high-pressure system back into the pump element.