High efficiency blood pump

1. A blood pump comprising:

a pump housing, wherein the pump housing provides an inlet, an outlet, and a bearing surface, wherein the pump is configured to move blood from the inlet to the outlet;

an impeller housed in the pump housing and having a plurality of blades joined by a central ring having an internal surface, wherein the impeller is radially supported by a hydrodynamic bearing formed by the internal surface and the bearing surface;

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 (i) being arranged to attract to each other in a radial direction perpendicular to the axis, and (ii) forming a radial magnetic coupling to transmit torque from the hub to the impeller;

wherein a maximum height of the plurality of blades overlaps with each of the internal surface and the radial magnetic coupling, the maximum height being in a direction of the axis;

wherein a topmost extent of the plurality of blades is axially closer to the inlet than is (a) a topmost extent of the internal surface and (b) a bottom of the plurality of blades.

2. The blood pump of claim 1 , wherein the impeller provides flow channels between circumferentially adjacent pairs of the plurality of blades.

3. The blood pump of claim 2 , wherein the flow channels have a maximum height that is substantially equal to the maximum height of the plurality of blades.

4. The blood pump of claim 1 , wherein each of the first permanent magnet and the second permanent magnet has a height in an axial direction parallel to the axis, and the heights of the first permanent magnet and the second permanent magnet overlap each other.

5. The blood pump of claim 1 , wherein the impeller is axially supported by a magnetic thrust bearing comprising a third permanent magnet positioned in the pump housing and a fourth permanent magnet positioned in the impeller.

6. The blood pump of claim 5 , wherein the fourth permanent magnet positioned in the pump housing is ring shaped.

7. The blood pump of claim 5 , wherein the third permanent magnet positioned in the impeller is located within at least one of the plurality of blades.

8. The blood pump of claim 1 , wherein the internal surface or the bearing surface provides at least one row of pattern grooves.

9. The blood pump of claim 1 , further comprising a row of herringbone grooves on the internal surface or the bearing surface.

10. The blood pump of claim 1 , wherein the internal surface or the bearing surface provides a multilobe shape.

11. The blood pump of claim 1 , wherein the internal surface is substantially parallel to the bearing surface.

12. The blood pump of claim 1 , wherein the internal surface is provided by an internal bore and the bearing surface is received within the bore.

13. The blood pump of claim 1 , wherein top surfaces of the impeller provide a second hydrodynamic bearing for axial support of the impeller.

14. The blood pump of claim 13 , wherein the top surfaces of the impeller provide at least one row of pattern grooves.

15. The blood pump of claim 13 , further comprising spiral grooves or spiral herringbone grooves on the top surfaces of the impeller.

16. The blood pump of claim 1 , wherein the blades are provided as an array of arc shaped segments.

17. The blood pump of claim 1 , wherein the pump housing comprises a non-ferromagnetic diaphragm that houses the hub.

18. The blood pump of claim 1 , wherein the impeller is an open type impeller or semi-open type impeller.