Roller cell pump
The very compactly constructed roller cell pump is driven mostly by an electric motor, and transports petrol at a pressure of approx. 6 bar to the injection valve(s). Despite the unsatisfactory lubrication properties of petrol, it manages without additional lubrication.
The armature, together with the collector runs in petrol and drives a drum whose rotation causes small rolling elements lying in slits on the
surrounding, slightly larger cylinder, to roll.
Because the drum is eccentrically mounted, a vacuum is developed there where the area is enlarged, and on the diminishing side, a pressure (on the left in the picture). Installed between the vacuum- and the
pressure side is a pressure release valve which opens with possible disturbances in the pressure pipe and protects the pump from overheating and destruction (on the right in the picture). In addition, at the exit, a
non-return valve prevents the pressure from dropping when the pump is switched off.
In the event of the connections being transposed, the armature and the drum rotate in the opposite direction. The non-return
valve however, prevents the possibly existing fuel from flowing back into the tank.