Rotary blood pump with opposing spindle magnets, bore and drive windings
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 method of pumping blood comprising:
providing a pump having a housing, a rotor, a spindle, a passive axial magnetic bearing and at least one hydrodynamic bearing; said passive axial magnetic bearing comprised of a rotor magnet assembly and a spindle magnet assembly, the rotor magnet assembly comprised of at least one rotor magnet with its magnetic vector being substantially parallel to an axis of said rotor and the spindle magnet assembly comprised of at least one spindle magnet with its magnetic vector being substantially parallel to an axis of said spindle;
pre-biasing said rotor axially in a first direction;
adjusting, if desired, said passive axial magnetic bearing so as to modify the pre-bias of said rotor in said first direction;
rotating said rotor;
supporting said rotor with said passive axial magnetic bearing;
exerting a force in a direction parallel to said first direction via said at least one hydrodynamic bearing; and,
thereby levitating said rotor.
2. The method of claim 1 , wherein the rotor magnet assembly further comprises first and second rotor magnets with the magnetic vector of each being substantially parallel with the axis of said rotor.
3. The method of claim 2 , wherein the first and second rotor magnets are concentrically located about a longitudinal axis of the rotor bore.
4. The method claim 1 , wherein said at least one hydrodynamic bearing is disposed on said rotor.
5. The method of claim 1 , wherein said at least one hydrodynamic bearing is disposed on said housing.
6. The method of claim 1 , wherein said at least one hydrodynamic bearing comprises a plurality of contoured surfaces disposed between said housing and said rotor.
7. The method according to claim 1 , wherein said step of exerting a force comprises exerting a force in a direction parallel and opposite to said first direction via said at least one hydrodynamic bearing.
8. The method according to claim 1 , wherein said adjusting of said passive axial magnetic bearing is performed by turning a set screw that causes longitudinal adjustment of said passive axial magnetic bearing.
9. A centrifugal pump for pumping a liquid comprising:
a pump housing having a pumping chamber and a spindle;
a rotor positioned around said spindle and being biased in a first direction;
a passive axial magnetic bearing supportive of said rotor at least in an axial direction; said passive axial magnetic bearing comprised of a first rotor magnet and a first spindle magnet wherein a magnetic vector of each of said first rotor magnet and said first spindle magnet are substantially parallel to an axis of said centrifugal pump;
a rotor bias adjustment mechanism axially and statically fixing a height of said first spindle magnet;
at least one hydrodynamic bearing generating forces in a direction parallel to said first direction when said rotor is in a rotating state;
wherein said passive axial magnetic bearing and said at least one hydrodynamic bearing combine to levitate said rotor during rotation of said rotor.
10. The centrifugal pump of claim 9 , wherein said passive axial magnetic bearing further comprises first and second spindle magnets arranged proximate each other with their respective magnetic vectors opposing each other, and first and second rotor magnets arranged proximate each other with their respective magnetic vectors opposing each other.
11. The centrifugal pump of claim 9 , wherein said passive axial magnetic bearing further comprises first and second spindle magnets arranged proximate each other with their respective magnetic vectors opposing each other.
12. The centrifugal pump of claim 9 , wherein said at least one hydrodynamic bearing is comprised of pads disposed on said housing.
13. The centrifugal pump of claim 9 , wherein said at least one hydrodynamic bearing is comprised of tapers disposed on said pump housing.
14. The centrifugal pump of claim 9 , wherein said at least one hydrodynamic bearing is disposed on said rotor.
15. The centrifugal pump of claim 9 , wherein said at least one hydrodynamic bearing is disposed on said pump housing.
16. The centrifugal pump of claim 9 , wherein said at least one hydrodynamic bearing comprises a plurality of contoured surfaces disposed between said pump housing and said rotor.
17. A centrifugal pump according to claim 9 , wherein said at least one hydrodynamic bearing generates forces in a direction parallel and opposite to said first direction when said rotor is in a rotating state.
18. A pump system comprising:
a control system for controlling operation of a pump;
a pump comprising:
housing having a pumping chamber and a spindle;
a rotor positioned around said spindle and being biased in a first direction;
a passive axial magnetic bearing supportive of said rotor at least in an axial direction, said passive axial magnet bearing comprised of a first spindle magnet and a first rotor magnet wherein a magnetic vector of each of said first spindle magnet and said first rotor magnet are substantially parallel to an axis of said pump;
a rotor bias adjustment mechanism axially and statically fixing a height of said first spindle magnet;
at least one hydrodynamic bearing generating forces in a direction parallel to said first direction when said rotor is in a rotating state;
wherein said passive axial magnetic bearing and said at least one hydrodynamic bearing combine to levitate said rotor during rotation of said rotor;
a source conduit connected to an inlet of said pump; and,
a destination conduit to an outlet of said pump.
19. The system according to claim 18 , wherein said pump is a blood pump.
20. The system according to claim 18 , further comprising a working fluid comprised of blood.