High efficiency blood pump
Blood pumps discussed herein may be suitable for use as a ventricular assist device (VAD) or the like. The blood pumps cause minimal blood damage, are energy efficient, and can be powered by implanted batteries for extended periods of time. Further, these pumps are also beneficial because they may improve the quality of life of a patient with a VAD by reducing restrictions on the patient's lifestyle. The blood pumps can provide radial and axial stability to a rotating impeller that is driven by a separate rotor. Both radial and axial stability can be provided, at least in part, by one or more permanent magnetic couplings between the rotor and the impeller and/or one or more permanent magnetic bearings between the pump housing and the impeller.
1. A blood pump comprising:
a pump housing having an inlet, an outlet, a first chamber, a second chamber, and a housing axial permanent magnet;
a rotor hub within the first chamber, the rotor hub being rotatable by a motor and comprising rotor hub radial permanent magnets; and
an impeller within the second chamber and comprising:
impeller axial permanent magnets that are axially spaced apart from and magnetically attracted to the housing axial permanent magnet; and
impeller radial permanent magnets that are radially spaced apart from and magnetically coupled to the rotor hub radial permanent magnets.
2. The blood pump of claim 1 , wherein the impeller is configured to be axially supported during rotation by a balance of:
a permanent magnetic bearing between the impeller axial permanent magnets and the housing axial permanent magnet;
a radial magnetic coupling formed between the impeller radial permanent magnets and the rotor hub radial permanent magnets; and
pressure forces generated by rotation of the impeller.
3. The blood pump of claim 1 , wherein the impeller is configured to be radially supported during rotation by a permanent magnetic bearing formed between the impeller axial permanent magnets and the housing axial permanent magnet.
4. The blood pump of claim 1 , wherein the housing axial permanent magnet is a ring magnet.
5. The blood pump of claim 4 , wherein the pump housing further comprises an additional ring magnet outside the housing axial permanent magnet.
6. The blood pump of claim 4 , wherein the pump housing further comprises an additional ring magnet inside the housing axial permanent magnet.
7. The blood pump of claim 1 , wherein the housing axial permanent magnet is one of a series of similarly polarized magnets that form a continuous magnetic field.
8. The blood pump of claim 1 , wherein, as the impeller rotates, radial restoring forces generated by the housing axial permanent magnet and the impeller axial permanent magnets are sufficient to overcome radial forces created by an attraction of the impeller radial permanent magnets and the rotor hub radial permanent magnets.
9. The blood pump of claim 1 , wherein, radially opposing surfaces of the impeller and the pump housing do not form a radial hydrodynamic bearing.
10. The blood pump of claim 1 , wherein, as the impeller rotates, radially opposing surfaces of the impeller and the pump housing are configured to form a radial bearing gap of greater than 0.005″.
11. The blood pump of claim 1 , wherein, as the impeller rotates, radially opposing surfaces of the impeller and the pump housing are configured to form a radial hydrodynamic bearing.
12. The blood pump of claim 1 , wherein the impeller further comprises a hydrodynamic bearing feature on a side of the impeller facing the housing axial permanent magnet.
13. The blood pump of claim 12 , wherein the hydrodynamic bearing feature is positioned between the impeller axial permanent magnets and the housing axial permanent magnet.
14. The blood pump of claim 1 , wherein, as the impeller rotates, axially opposing surfaces of the impeller and the pump housing are configured to form an axial bearing gap of greater than 0.005″.
15. A method of pumping blood, the method comprising:
with a motor, rotating a rotor hub within a first chamber of a pump housing, the rotor hub comprising rotor radial permanent magnets;
with the rotor hub, rotating an impeller within a second chamber of the pump housing, the impeller comprising impeller axial permanent magnets and impeller radial permanent magnets;
radially stabilizing the impeller with a permanent magnetic bearing formed between the impeller axial permanent magnets and a housing axial permanent magnet residing within the pump housing; and
axially stabilizing the impeller with a radial magnetic coupling between the impeller radial permanent magnets and the rotor radial permanent magnets.
16. The method of claim 15 , wherein axially stabilizing the impeller comprises maintaining a balance of:
the permanent magnetic bearing;
the radial magnetic coupling; and
pressure forces generated by rotation of the impeller.
17. The method of claim 15 , wherein, as the impeller rotates, radial restoring forces generated by the housing axial permanent magnet and the impeller axial permanent magnets are sufficient to overcome radial forces created by an attraction of the impeller radial permanent magnets and the rotor radial permanent magnets.
18. The method of claim 15 , wherein, as the impeller rotates, radially opposing surfaces of the impeller and the pump housing do not form a radial hydrodynamic bearing.
19. The method of claim 15 , wherein, as the impeller rotates, radially opposing surfaces of the impeller and the pump housing form a radial bearing gap of greater than 0.005″.
20. The method of claim 15 , wherein, as the impeller rotates, radially opposing surfaces of the impeller and the pump housing form a radial hydrodynamic bearing.
21. The method of claim 15 , wherein, as the impeller rotates, axially opposing surfaces of the impeller and the pump housing form an axial bearing gap of greater than 0.005″.