Patent ID: 8807968

Claim:
A centrifugal pump apparatus for pumping a liquid comprising: a housing; a rotor having a bore, the rotor having at least one blade; 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 extending into said bore, 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 is set so that the spindle and rotor magnet assemblies attract each other; at least one hydrodynamic bearing disposed between said rotor and said housing; and, at least one drive magnet carried by 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.