Patent ID: 6736616
Filing Date: 2004-05-18
Classification: F04D,H02K

Abstract:
A centrifugal pump which comprises:a housing; an impeller; and an electrical motor having an axis of rotation; wherein said motor includes an annular stator and a permanently magnetized, circular rotor secured to the impeller and concentrically mounted within said stator; said rotor having a first circular end of a given diameter, proximate to said impeller and an axially opposite second circular end having a smaller diameter than said given diameter; a single-ball bearing loosely supporting said rotor and impeller; a support shaft, having a tip mounting said bearing, axially extending from said housing into an axial cavity in said second circular end; wherein said rotor has a circular peripheral outer face between said first and second end; said stator has a soft magnetic annular yoke having an inner surface mirroring said outer face and separated from it by a narrow gap, and an annular winding positioned within said gap; whereby magnetic forces generated by said rotor urge said rotor axially against said bearing in the absence of an electrical supply to said motor.