Patent ID: 8047816
Filing Date: 2011-11-01
Classification: F04D

Abstract:
1. An electric centrifugal pump comprising: a case defining an outer shape of the centrifugal fan and including an inflow portion and an outflow portion; a pump chamber provided inside the case and including a liquid passage; an impeller arranged in the pump chamber and being rotatable about an axis to generate a vortex flow of the liquid which flows into the pump chamber via the inflow portion and flows out via the outflow portion; a magnetically driving portion rotatable about the axis together with the impeller; and an armature facing the magnetically driving portion with a gap arranged therebetween, the armature being arranged to generate a rotational magnetic field; a shaft arranged coaxial or substantially coaxial with the axis of rotation of the impeller and an axial lower end of the shaft being fixed to the case; a sleeve rotatable about the axis together with the impeller and the magnetically driving portion and including an inner circumferential surface which is slidable on an outer circumferential surface of the shaft above the axially lower end of the shaft; and a sleeve retaining portion arranged above an upper end of the shaft, extending axially upward beyond an axial upper surface of the sleeve, and including a portion axially facing the axial upper surface of the sleeve to prevent axially upward movement of the sleeve; wherein the centrifugal pump defines a portion of the liquid passage from the inflow portion to the outflow portion, the impeller includes a plurality of blades radially arranged about the axis and circumferentially spaced from one another; the blades are generally straight in both a radial direction perpendicular or substantially perpendicular to the axis and an axial direction parallel or substantially parallel to the axis; the centrifugal pump is driven in a single rotation direction and a radially outer end of each of the blades is located circumferentially upstream from a radially inner end thereof with respect to the single rotation direction; and an axial uppermost end of the sleeve retaining portion is arranged axially below axially uppermost ends of the blades.