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 housing defining a pump chamber lumen;
a rotor within said lumen, the rotor rotatable on a rotation axis concentric with the lumen and having:
an outer periphery;
a blood upstream end;
a blood downstream end opposite the blood upstream end;
a plurality of magnetic drive poles by which the rotor is configured to rotate to direct blood flow axially within the lumen;
at least one of a magnetic bearing and a hydrodynamic bearing surface configured to enable the rotor to rotate in a freely suspended configuration within the lumen;
a tapered axial extension at the blood downstream end, the tapered axial extension configured to enhance downstream blood flow characteristics in an axial direction when the rotor is rotating; and
a plurality of grooves disposed in the axial direction, the plurality of grooves defining a plurality of peripheral land surfaces and at least one flow channel within the respective plurality of grooves, the plurality of peripheral land surfaces being discrete and radially facing and including an interior base width and a radially facing surface width, the interior base width being narrower than the radially facing surface width, and including the at least one of the magnetic bearing and the hydrodynamic bearing surface coupled thereto, and the at least one flow channel extending from a location proximate the blood upstream end to a location proximate the blood downstream end and including:
a curved shape;
a substantially axially extending outlet channel proximate the blood downstream end configured to drive blood in an axial direction as the rotor is rotated; and
a width being at least one of substantially equal to and less than a collective total width of the plurality of peripheral land surfaces at the outer periphery of the rotor; and
a stator positioned exterior to the lumen, the stator configured to be energized and magnetically coupled with the plurality of magnetic drive poles of the rotor to cause the rotor to rotate in the lumen.
2. The blood pump of claim 1 , further comprising a plurality of rotors within the lumen, the plurality of rotors axially aligned and spaced apart from each other and disposed in the direction of blood flow within the lumen.
3. The blood pump of claim 2 , in which the rotors are ganged together on a common shaft to rotate together as one in the same direction.
4. The blood pump of claim 2 , in which each rotor is suspended to rotate independently.
5. The blood pump of claim 2 , in which each rotor rotates in a different rotational direction from at least one of an immediate upstream adjacent rotor and an immediate downstream adjacent rotor.
6. The blood pump of claim 2 , in which each rotor rotates at a different rotational speed from at least one of an immediate upstream adjacent rotor and an immediate downstream adjacent rotor.
7. The blood pump of claim 1 , in which the hydrodynamic bearing surface is positioned in one of the plurality of peripheral land surfaces, the hydrodynamic bearing surface configured to provide hydrodynamic control of a radial position of the rotor within the lumen when the rotor is in a state of rotation.
8. The blood pump of claim 1 , in which the plurality of peripheral land surfaces of the rotor have substantially equal surface areas collectively defining a cylindrical periphery of the rotor, the cylindrical periphery of the rotor and an interior wall of the lumen defining a gap therebetween.
9. The blood pump of claim 8 , in which each of the plurality of peripheral land surfaces 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 defining a gap larger than a gap defined by each of the tapered hydrodynamic bearing surfaces for hydrodynamic thrust control of a radial position of the rotor within the lumen.
10. The axial flow blood pump of claim 8 , in which the plurality of peripheral land surfaces comprise a plurality of hydrodynamic thrust bearing surfaces in the gap configured to provide hydrodynamic thrust control of a radial position of the rotor within the lumen when the rotor is rotating.
11. The blood pump of claim 7 , in which the at least one hydrodynamic bearing surface comprises at least one shroud side wall extending substantially transverse to the rotation axis of the rotor.
12. The blood pump of claim 1 , wherein:
the lumen comprises a first reduced interior diameter section adjacent at least one of the upstream and downstream ends of the rotor; and
each of the plurality of peripheral land surfaces comprises a second hydrodynamic bearing surface adjacent the first reduced interior diameter section of the lumen.
13. The blood pump of claim 12 , wherein:
the lumen comprises a second reduced interior diameter section at an end of the rotor opposite the end of the lumen defining the first reduced interior diameter section and
each of the plurality of peripheral land surfaces comprises a third hydrodynamic bearing surface adjacent the second reduced interior diameter section of the lumen.
14. The blood pump of claim 1 , further comprising at least one magnetic bearing including a component exterior to the lumen, the at least one magnetic bearing magnetically coupled to the rotor and configured to control an axial position of the rotor in the lumen when the rotor is rotating.
15. A blood pump comprising:
a housing defining a pump chamber lumen;
a rotor within the lumen, the rotor configured to be rotatable on a rotation axis concentric with the lumen and configured direct blood flow axially within the lumen, the rotor having:
a blood upstream end;
a blood downstream end opposite the blood upstream end;
a plurality of magnetic drive poles by which the rotor is configured to rotate;
a magnetic bearing surface configured to enable the rotor to rotate in a freely suspended configuration within the lumen;
a tapered axial extension at the blood downstream end, the tapered axial extension configured to enhance downstream blood flow characteristics in an axial direction when the rotor is rotating; and
a plurality of grooves disposed in the axial direction, the plurality of grooves defining a plurality of peripheral land surfaces and at least one flow channel within the respective plurality of grooves, the plurality of peripheral land surfaces being discrete and radially facing and including an interior base width and a radially facing surface width, the interior base width being narrower than the radially facing surface width, and including the at least one of the magnetic bearing and the hydrodynamic bearing surface coupled thereto, and the at least one flow channel extending from a location proximate the blood upstream end to a location proximate the blood downstream end and including:
a curved shape;
a substantially axially extending outlet channel proximate the blood downstream end configured to drive blood in an axial direction as the rotor is rotated; and
being at least one of substantially equal to and less than a collective total width of the plurality of peripheral land surfaces at the outer periphery of the rotor; and
a stator positioned exterior to the lumen, the stator configured to be energized and magnetically coupled with the plurality of magnetic drive poles of the rotor to cause the rotor to rotate in the lumen.
16. The blood pump of claim 15 , further comprising:
a plurality of rotors within the lumen, the plurality of rotors axially aligned and spaced apart from each other in a direction of blood flow within the lumen.
17. The blood pump of claim 15 , further comprising:
a hydrodynamic bearing surface positioned in one of the plurality of peripheral land surfaces, the hydrodynamic bearing surface configured to provide hydrodynamic control of a radial position of the rotor within the lumen when the rotor is in a state of rotation.
18. The blood pump of claim 15 , in which the plurality of peripheral land surfaces of the rotor have substantially equal surface areas collectively defining a cylindrical periphery of the rotor, said cylindrical periphery defining a gap between the cylindrical periphery of the rotor and an interior wall of the lumen.