Patent ID: 8579607

Claim:
A centrifugal pump apparatus for pumping a liquid comprising: a housing; a rotor having a bore, the rotor comprising an impeller having at least one blade; and a rotor magnet assembly comprising a first and a second magnet disposed within the rotor, wherein the first and second magnets are arranged proximate each other with their respective magnetic vectors being substantially parallel to an axis of said rotor; a spindle associated with said rotor, said spindle having a spindle magnet assembly comprising a third and a fourth magnet disposed within the spindle, wherein the third and fourth magnets are arranged proximate each other with their respective magnetic vectors being substantially parallel with an axis of said spindle, and said rotor magnet assembly and said spindle magnet assembly constituting a passive axial magnetic bearing wherein a relative orientation of the spindle and rotor magnet assemblies are selected so that the spindle and rotor magnet assemblies attract each other; a surface geometry including a plurality of features that create a change in clearance between said rotor and said housing and thereby create at least one hydrodynamic bearing; and, at least one drive magnet carried by said rotor, said at least one drive magnet having a magnetic vector substantially parallel to said axis of said rotor; wherein said passive axial magnetic bearing and said at least one hydrodynamic bearing constitute the sole bearings for levitating said rotor during rotation of said rotor.