Centrifugal pump with an axial-field integral motor cooled by working

Abstract

An integral axial-field motor pump, includes a housing assembly having a working fluid inlet, a working fluid discharge, and a stationary shaft mounted therein. A motor stator is mounted in the housing assembly radially surrounding the stationary shaft and having a seal to prevent exposure to the working fluid; and a motor rotor is axially spaced from the stator and fixed to an impeller having a hub and journaled, by a bearing fixed in the hub, on the stationary shaft within the housing assembly. The rotor also has a seal to prevent exposure to the working fluid. The stationary shaft has an axial passageway formed within it; and there is a provision for conducting working fluid from the working fluid discharge, along sealed surfaces of the rotor and the stator, through the axial passageway within the stationary shaft, to the working fluid inlet to extract heat from the rotor and the stator and to cool the bearing. The threaded engagement of the stationary shaft in the blind hole of the pump case provides for jacking action on the rotor to overcome magnetic forces between the rotor and stator encountered during installation and removal of a permanent magnet equipped motor rotor. Cooling is provided for the working fluid extracted from the fluid discharge prior to introducing it to the cooling channels, when pumping hot fluids.