Patent ID: 8177528

Claim:
A pump for liquid medium, comprising: a pump casing containing: a forward pumping section having an inlet and an outlet, and a rearward magnetic coupling section having an inner magnetic rotor and outer magnetic rotor separated by a separation can, which outer magnetic rotor transmits rotation via magnetic coupling to the inner magnetic rotor, a main pump in the pumping section that is a rotarty positive displacement pump that provides suction through the inlet and discharges through the outlet, whereby the main pump is mechanically connected to a rotor shaft mounted in a plane bearing, which shaft is connected to the inner magnetic rotor, a circulation pump in the pumping section configured to cool the plane bearing and magnetic coupling, wherein the circulation pump is a rotary positive displacement pump mechanically connected to said rotor shaft; a rearward annular passageway, RAP, concentrically arranged over a rearward end of the plane bearing and whereby a forward face of the hub of the inner magnetic rotor forms a boundary surface of the RAP, a concentric ring chamber connects the RAP with the rearward end of the plane bearing, a longitudinal supply passage in the casing running from outlet of the circulation pump towards said hub, whereby the longitudinal supply passage opens into said (RAP); and a plurality of apertures in said hub running in a longitudinal direction from the forward to the rearward face of the hub, said arrangement allowing medium from the outlet of the circulation pump to flow across the plane bearing and across a gap between the separation can and inner magnetic rotor.