Rotary blood pump with opposing spindle magnets, bore and drive windings
View Patent ↗Various “contactless” bearing mechanisms including hydrodynamic and magnetic bearings are provided for a rotary pump as alternatives to mechanical contact bearings. In one embodiment, a pump apparatus includes a pump housing defining a pumping chamber. The housing has a spindle extending into the pumping chamber. A spindle magnet assembly includes first and second magnets disposed within the spindle. The first and second magnets are arranged proximate each other with their respective magnetic vectors opposing each other. The lack of mechanical contact bearings enables longer life pump operation and less damage to working fluids such as blood.
1. 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.
2. The apparatus of claim 1 wherein the rotor magnet assembly further comprises a pole piece disposed between the first and second magnets.
3. The apparatus of claim 1 wherein at least one of the first and second rotor magnets has a ring shaped form factor.
4. The apparatus of claim 1 wherein the first and second rotor magnets are concentrically located about a longitudinal axis of the rotor bore.
5. The apparatus of claim 1 wherein said features are disposed on said rotor.
6. The apparatus of claim 1 wherein said features are disposed on said housing.
7. The apparatus of claim 1 wherein said features are comprised of pads disposed on said housing.
8. The apparatus of claim 1 , wherein said features are comprised of tapers disposed on said housing.
9. A centrifugal pump apparatus for pumping a liquid comprising:
a pump housing defining a pumping chamber, the pump housing having a spindle extending into the pumping chamber;
a rotor configured to rotate about the spindle, the rotor including an impeller comprising at least one blade;
a rotor portion of a magnetic bearing disposed within a non-bladed portion of the rotor;
a spindle portion of the magnetic bearing disposed within the spindle,
said rotor portion and said spindle portion of said magnetic bearing constituting a passive axial magnetic bearing
wherein the spindle and rotor portions of the magnetic bearing are configured to attract each other,
wherein at least one of the rotor and spindle portions of the magnetic bearing comprises a first and a second magnet,
wherein the first and second magnets are arranged proximate each other with their respective magnetic vectors being substantially parallel to an axis of said at least one of said rotor and spindle; 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;
a surface geometry including a plurality of features that create a change in the clearance between said rotor and said housing and thereby create at least one hydrodynamic bearing; and,
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.
10. The apparatus of claim 9 wherein the spindle portion of the magnetic bearing comprises first and second magnets arranged proximate each other with their respective magnetic vectors opposing each other, wherein the rotor portion of the magnetic bearing comprises first and second magnets arranged proximate each other with their respective magnetic vectors opposing each other.
11. The apparatus of claim 9 wherein the spindle portion of the magnetic bearing comprises first and second magnets arranged proximate each other with their respective magnetic vectors opposing each other, wherein the rotor portion of the magnetic bearing comprises ferromagnetic material.
12. The apparatus of claim 11 wherein the ferromagnetic material is soft iron.
13. The apparatus of claim 9 wherein the rotor portion of the magnetic bearing comprises first and second magnets arranged proximate each other with their respective magnetic vectors opposing each other, wherein the spindle portion of the magnetic bearing comprises ferromagnetic material.
14. The apparatus of claim 13 wherein the ferromagnetic material is soft iron.