Claims
- 1. A cardiac assist device comprising:
a housing having an inlet and an outlet; a rotor assembly adapted for rotation about a drive axis including a primary impeller for transporting blood from the inlet to the outlet, and a secondary impeller for cycling blood through a bearing interfaced between the impeller assembly and the housing, the secondary impeller having a series of spaced blades circumferentially spaced about the drive axis and disposed in substantially radial orientation for improving recirculation through the blood bearing.
- 2. The invention of claim 1 wherein the secondary impeller blades extend axially outwardly from the rotor assembly.
- 3. The invention of claim 2 wherein the secondary impeller blades have a varying height over a radial dimension.
- 4. The invention of claim 2 wherein the secondary impeller blades have rounded edges.
- 5. The invention of claim 2 wherein the secondary impeller blades have a scalloped undercut whereby an outer radial portion of each blade extends outwardly a greater dimension than an inner radial portion of each blade.
- 6. The invention of claim 5 wherein the secondary impeller blades are disposed on a face of the rotor and the scalloped undercut includes a concave surface extending inwardly in each blade from an outer radial edge to an inner radial edge.
- 7. The invention of claim 1 wherein each blade of the secondary impeller has a concave surface.
- 8. The invention of claim 1 further comprising an inverted motor and fluid film bearing including a stator received on a post formed by an axial extension of the housing and receiving an annular rotor having a drive magnet disposed therein that is radially supported and rotationally driven by the stator, a clearance defined between the annular rotor and housing extension defining a bearing that is supplied with a well-washed circulating flow of blood by the secondary impeller.
- 9. The invention of claim 8 wherein the rotor has an elongated axial dimension with the primary impeller located at a first end thereof and the secondary impeller located at a second end thereof.
- 10. The invention of claim 8 wherein the inlet extends axially and the outlet extends tangentially from the housing.
- 11. A blood pump having an improved bearing blood lubricated fluid film bearing, the blood pump comprising:
a housing having an inlet and outlet communicating with a pump chamber, and a portion extending into the chamber; a rotor assembly received in the chamber for rotation about a drive axis and having a first impeller for pumping blood from the inlet to the outlet and a second impeller for maintaining blood flow through a fluid film bearing defined between an interface of the rotor assembly and housing, the second impeller including a set of blades extending radially outward from the drive axis and each having rounded edges; and stator winding and magnet ring components of a drive assembly for rotating the rotor assembly within the housing chamber.
- 12. The blood pump of claim 11 wherein the secondary impeller blades extend axially outward from the rotor assembly a greater dimension at a radial outer edge than a radial inner edge.
- 13. The blood pump of claim 12 wherein the secondary impeller blades extend outwardly beyond the outer diameter of the rotor assembly.
- 14. The blood pump of claim 13 wherein the second impeller blades have a concave, rounded contour extending from the radial outer edge to the radial inner edge.
- 15. The blood pump of claim 11 wherein the drive assembly includes a stator winding disposed in the housing portion.
- 16. The blood pump of claim 15 wherein the drive assembly includes a magnet disposed in the rotor assembly.
- 17. The blood pump of claim 11 wherein the fluid film bearing includes a reduced dimensioned passageway interposed between the rotor assembly and the housing portion.
- 18. The blood pump of claim 17 wherein the housing portion is non-circular in cross-section.
- 19. The blood pump of claim 11 wherein radial inner portions of the second impeller blades are dimensioned to have a larger clearance with the housing than outer tips of the blades.
- 20. The blood pump of claim 19 wherein radial inner portions of the second impeller blades are approximately one-half the height of the outer tips of the blades.
FEDERAL RESEARCH STATEMENT
[0001] The U.S. Government may have certain rights in this invention pursuant to contract number N01-HV-58159 awarded by the U.S. National Heart, Lung and Blood Institute of the National Institutes of Health.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/US01/40329 |
3/19/2001 |
WO |
|