Flow thru mechanical blood pump bearings

• US 10,294,944 B2
• Filed: 03/08/2013
• Issued: 05/21/2019
• Est. Priority Date: 03/08/2013
• Status: Active Grant

• Current Assignee: Corvion Incorporated
• Original Assignee: EverHeart Systems Inc.
• Inventors: Aber, Greg S., Rhoades, Allan S.
• Primary Examiner(s): Omgba, Essama
• Assistant Examiner(s): Nichols, Charles
• Application Number:
  US13/790,239
• Publication Number:
  US 20140255225A1
• Time in Patent Office: 2,265 Days
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/216 including a rotating member acting on the blood, e.g. impeller
• CPC Class Codes: A61M 60/419 the force acting on the blood contacting member being permanent magnetic, e.g. from a rotating magnetic coupling between driving and driven magnets
• CPC Class Codes: A61M 60/422 the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps
• CPC Class Codes: A61M 60/81 Pump housings
• CPC Class Codes: A61M 60/824 Hydrodynamic or fluid film bearings
• CPC Class Codes: A61M 60/825 Contact bearings, e.g. ball-and-cup or pivot bearings
• CPC Class Codes: F04D 13/024 a magnetic coupling
• CPC Class Codes: F04D 13/06 the pump being electrically driven
• CPC Class Codes: F04D 13/0633 Details of the bearings
• CPC Class Codes: F04D 29/047 hydrostatic; hydrodynamic

Abstract

A flow thru mechanical bearing system can be used in an implantable rotary blood pump that includes a pump housing. An impeller housed in the pump housing can be radially supported by a row of at least three low friction contact points located on an inside bore of the impeller. The impeller may be axially supported by a second mechanical bearing. The second mechanical bearing may provide at least three axial contact points on the top surfaces of the impeller. The impeller is driven by a magnetic coupling which functions mainly to transmit torque to the impeller. Further, in some cases, the magnetic coupling may restrain axial motion of the impeller.

Claims

1. A blood pump comprising:

a pump housing providing an inlet, an outlet, and a bearing surface;

an impeller housed in the pump housing and having a plurality of blades joined by a central ring;

at least three contact protrusions circumferentially spaced on an internal surface of the impeller, wherein the impeller is radially supported by the contact protrusions sliding on the bearing surface; and

a hub configured to rotate about an axis and comprising a first permanent magnet, wherein the impeller comprises a second permanent magnet located within the central ring, the first permanent magnet and the second permanent magnet overlapping each other in a direction of the axis and forming a radial magnetic coupling to transmit torque from the hub to the impeller;

wherein a first portion of at least one of the plurality of blades defines a maximum height of the plurality of blades that is greater than or equal to heights of all other portions of the plurality of blades, as measured in a direction that is parallel to the axis;

wherein each of the contact protrusions is axially between a top end of the first portion and a bottom end of the first portion, the bottom end being axially opposite the top end;

wherein the radial magnetic coupling is axially between the top end of the first portion and the bottom end of the first portion;

wherein a topmost extent of the plurality of blades is axially closer to the inlet in a direction of the axis than is (a) a topmost extent of each of the contact protrusions and the radial magnetic coupling and (b) a bottom of the plurality of blades;

wherein at least a portion of the inlet extends along the axis and is positioned on a side of the impeller that is axially opposite the bottom of the plurality of blades.

2. The blood pump of claim 1, wherein said contact protrusions are semi-spherically shaped, semi-ellipsoid shaped, or concave shaped.

3. The blood pump of claim 1, further comprising:

a motor housing, wherein the motor housing houses a motor; and

wherein the magnetic coupling causes the impeller to rotate when the motor rotates, and said magnetic coupling supports the impeller axially.

4. The blood pump of claim 1 further comprising:

an impeller chamber defined by the pump housing, wherein the impeller is housed in the impeller chamber; and

a motor housing defining a motor chamber, wherein a motor is housed in the motor chamber;

wherein the bearing surface separates the motor chamber and the impeller chamber.

5. The blood pump of claim 1, wherein the bearing surface and/or the contact protrusions of the impeller are coated with Diamond Like Carbon (DLC).

6. The blood pump of claim 1, wherein the radial contact protrusions have a sliding coefficient of friction of 0.15 or less.

7. The blood pump of claim 1, wherein the bearing surface is aluminum oxide, zirconium dioxide, silicon carbide, or silicon nitride.

8. The blood pump of claim 1, wherein the contact protrusions are aluminum oxide, zirconium dioxide, silicon carbide, or silicon nitride.

9. The blood pump of claim 1, wherein a radial load acting on any one of said contact protrusions is 0.5 N or less.

10. The blood pump of claim 1, wherein a total mechanical power consumed by said contact protrusions is 0.5 watts or less.

11. The blood pump of claim 1, wherein the impeller is an open pressure balanced type impeller that minimizes axial thrust during operation of the blood pump.

12. The blood pump of claim 1, wherein a clearance between the bearing surface and the internal surface of the impeller is 0.005 inches or greater.

13. The blood pump of claim 1, further comprising at least three axial contact protrusions positioned on top surfaces of blades of the impeller for axial support of the impeller.

14. The blood pump of claim 13, wherein the axial contact protrusions are semi-spherically shaped, semi-ellipsoid shaped, or flat shaped.

15. The blood pump of claim 13, wherein the axial contact protrusions slide on an inside surface of the pump housing.

16. The blood pump of claim 15, wherein the inside surface of the pump housing and/or axial contact protrusions are coated with Diamond Like Carbon (DLC).

17. The blood pump of claim 15, wherein the axial contact protrusions have a sliding coefficient of friction of 0.15 or less.

18. The blood pump of claim 15, wherein the inside surface of the pump housing is aluminum oxide, zirconium dioxide, silicon carbide, or silicon nitride.

19. The blood pump of claim 13, wherein the axial contact protrusions are aluminum oxide, zirconium dioxide, silicon carbide, or silicon nitride.

20. The blood pump of claim 13, wherein an axial load acting on any one of said axial contact protrusions is 0.5 N or less.

21. The blood pump of claim 13, wherein a total mechanical power consumed by said axial contact protrusions is 0.5 watts or less.

22. The blood pump of claim 13, wherein the impeller is an open pressure balanced type impeller that minimizes axial thrust during operation of the pump.

23. The blood pump of claim 15, wherein a clearance between said top surfaces of impeller and said inside surface of pump housing is 0.005 inches or greater.