Axial flow pump with multi-grooved rotor
An axial-flow blood pump for pumping blood includes a substantially cylindrical outer enclosure. A tubular housing concentric with and located within the outer enclosure has at one end an inlet and at an opposite end an outlet. A motor stator is concentric with and located between the outer enclosure and the tubular housing. An impeller is concentric with and located within the tubular housing. The impeller is suspended in operation by a combination of passive magnetic forces between magnets within the impeller or magnetized regions of the impeller and the motor stator and hydrodynamic thrust forces generated as blood flows between the tubular housing and a plurality of hydrodynamic thrust bearing surfaces located on the impeller. A volute may be in fluid-tight connection with the outlet of the tubular housing for receiving blood in the axial direction and directing blood in a direction normal to the axial direction. The volute has a flow-improving member extending axially from the volute and into and coaxially with the tubular housing.
1. A blood pump, comprising:
a pump housing;
a rotor positioned within the housing, the rotor having an axis of rotation, a leading edge at an upstream end of the rotor and a trailing edge at a downstream end of the rotor, the rotor comprising peripheral land surfaces defined by one or more flow channels extending from the leading edge to the trailing edge, a collective width of the flow channels in a circumferential direction of the rotor at each of a plurality of axial positions on a radial periphery of the rotor being less than a collective total width of the peripheral land surfaces in the circumferential direction at the plurality of axial positions, the rotor further having a hydrodynamic bearing surface configured to enable the rotor to rotate freely suspended, the rotor including a plurality of magnetic poles; and
a stator including an electrically activated coil configured to magnetically interact with the magnetic poles to cause the rotor to rotate.
2. The blood pump of claim 1 , wherein the average depth of each flow channel is within the range of 1 mm to about 5 mm.
3. The blood pump of claim 1 , wherein the flow channels are substantially parallel.
4. The blood pump of claim 1 , wherein the depth of each flow channel is greater at the leading edge of the rotor than at the trailing edge.
5. The blood pump of claim 1 , further comprising a plurality of rotors within the housing axially aligned and spaced apart in the direction of blood flow within the housing.
6. The blood pump of claim 5 , wherein the plurality of rotors are arranged together along a common shaft to rotate together as one in the same direction.
7. The blood pump of claim 5 , wherein each rotor is suspended to rotate independently.
8. The blood pump of claim 5 , wherein each rotor rotates in a different rotational direction from at least one of an immediate upstream adjacent rotor and an immediate downstream adjacent rotor.
9. The blood pump of claim 1 , wherein at least one the hydrodynamic bearing surface is positioned in one of the peripheral land surface areas and is configured to provide hydrodynamic control of a radial position of the rotor within the housing in a state of rotation of the rotor.
10. The blood pump of claim 1 , wherein the peripheral land surface areas of the rotor have substantially equal surface areas collectively defining a cylindrical periphery of the rotor, the blood pump defining a gap between the cylindrical periphery of the rotor and an interior wall of the housing.
11. The blood pump of claim 10 , wherein each of the peripheral land surface areas comprises a first tapered hydrodynamic bearing surface extending in a substantially circumferential direction adjacent the blood upstream end of the rotor and a second tapered hydrodynamic bearing surface extending in a substantially circumferential direction adjacent the blood downstream end of the rotor, each of the first and second tapered hydrodynamic bearing surfaces having an entrance portion, the gap being larger at each of the entrance portions of the hydrodynamic bearing surfaces than at other portions of each of the tapered hydrodynamic bearing surfaces for hydrodynamic thrust control of a radial position of the rotor within the housing.
12. The blood pump of claim 10 , wherein the peripheral land surface areas comprise the hydrodynamic thrust bearing surfaces for hydrodynamic thrust control of a radial position of the rotor within the gap when the rotor is rotating.
13. The blood pump of claim 11 , wherein the at least one hydrodynamic bearing surface comprises shroud side walls extending substantially transverse to the rotation axis of the rotor.
14. The blood pump of claim 1 , wherein the housing comprises a first reduced interior diameter section adjacent one end of the rotor, each of the peripheral land surface areas comprising at least one the hydrodynamic bearing surface adjacent the first reduced interior diameter section for hydrodynamic thrust control of an axial position of the rotor within the housing.
15. The blood pump of claim 14 , wherein the housing comprises a second reduced interior diameter section at another end of the rotor opposite the one end, each of the peripheral land surface areas comprising a second hydrodynamic bearing surface adjacent the second reduced interior diameter section for hydrodynamic thrust control of the axial position of the rotor within the tubular housing.
16. A blood pump, comprising:
a pump housing;
a rotor for pumping blood positioned in the housing, the rotor having an axis of rotation, a leading edge at a blood upstream end of the rotor, and a trailing edge at a blood downstream end of the rotor, the rotor comprising a radially projection-free periphery defined by a plurality of peripheral land surfaces and one or more flow channels extending radially inwardly from the periphery separating the peripheral land surfaces, the one or more flow channels extending from the leading edge to the trailing edge, the rotor further having a hydrodynamic bearing surface configured to enable the rotor to rotate freely suspended within the housing, the rotor including a plurality of magnetic poles; and
a stator including an electrically activated coil configured to magnetically interact with the magnetic poles to cause the rotor to rotate.
17. The blood pump of claim 16 , wherein the housing comprises a first reduced interior diameter section adjacent one end of the rotor, each of the peripheral land surface areas comprising at least one the hydrodynamic bearing surface adjacent the first reduced interior diameter section for hydrodynamic thrust control of an axial position of the rotor within the housing.
18. The blood pump of claim 17 , wherein at least one the hydrodynamic bearing surface is positioned in one of the peripheral land surface areas and is configured to provide hydrodynamic control of a radial position of the rotor within the housing in a state of rotation of the rotor.
19. The blood pump of claim 16 , wherein the peripheral land surface areas of the rotor have substantially equal surface areas collectively defining the cylindrical periphery of the rotor, the housing defining a gap between the cylindrical periphery of the rotor and an interior wall of the housing.
20. The blood pump of claim 19 , wherein each of the peripheral land surface areas comprises a first tapered hydrodynamic bearing surface extending in a substantially circumferential direction adjacent the blood upstream end of the rotor and a second tapered hydrodynamic bearing surface extending in a substantially circumferential direction adjacent the blood downstream end of the rotor, each of the first and second tapered hydrodynamic bearing surfaces having an entrance portion, the gap being larger at each of the entrance portions of the hydrodynamic bearing surfaces than at other portions of each of the tapered hydrodynamic bearing surfaces for hydrodynamic thrust control of a radial position of the rotor within the housing.