Magnetically-levitated blood pump with optimization method enabling miniaturization

Patent metadata

Field	Value
Publication number	US-9314557-B2
Application number	US-200913054903-A
Country	US
Kind code	B2
Filing date	Sep 24, 2009
Priority date	Sep 26, 2008
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A magnetically-levitated blood pump with an optimization method that enables miniaturization and supercritical operation. The blood pump includes an optimized annular blood gap that increases blood flow and also provides a reduction in bearing stiffness among the permanent magnet bearings. Sensors are configured and placed optimally to provide space savings for the motor and magnet sections of the blood pump. Rotor mass is increased by providing permanent magnet placement deep within the rotor enabled by a draw rod configuration.

First claim

What is claimed is:

1. A magnetically-levitated blood pump, said blood pump comprising:
an inflow end providing for entry of blood;
an outflow end providing for exit of said blood;
a first sensor coil located at a blood flow convergence adjacent said inflow end, and a second sensor coil located at a blood flow divergence adjacent said outflow end;
a stator oriented in axial alignment with, and located between, said inflow end and said outflow end, and including a magnetic gap Sr, a plurality of stator permanent magnets, at least one voice coil, and a motor coil;
a rotor centered within said stator, and including a radius Rr and a plurality of rotor permanent magnets, the rotor adapted for supercritical operation;
a first permanent magnet bearing arranged near said inflow end to radially stabilize and center the rotor, and formed from a first portion of said stator permanent magnets and a first corresponding portion of said rotor permanent magnets;
a second permanent magnet bearing arranged near said outflow end to radially stabilize and center the rotor, and formed from a second portion of said stator permanent magnets and a second corresponding portion of said rotor permanent magnets;
a motor magnet for interaction with said motor coil, and formed from a third corresponding portion of said rotor permanent magnets;
a fourth corresponding portion of said rotor permanent magnets for interaction with said at least one voice coil, said at least one voice coil configured to additionally interact with said first corresponding portion of said rotor permanent magnets to stabilize the rotor in an axial direction; and
a fluid gap Wg defined by the magnetic gap Sr minus the rotor radius Rr,
wherein the supercritical operation of the rotor and the fluid gap Wg provides for the blood pump to be adapted for miniaturization and for minimally-invasive implantation.

2. The blood pump as claimed in claim 1 wherein said rotor permanent magnets occupy a majority of inner volume of said rotor.

3. The blood pump as claimed in claim 1 further including an outer housing cover for encapsulating said stator, said outer housing having a dome providing space for electrical connections to and from said blood pump.

4. The blood pump as claimed in claim 1 wherein said fourth corresponding portion of said rotor permanent magnets include voice coil magnets having radially outward, axial, and radially inward magnetization directions.

5. The blood pump as claimed in claim 1 wherein a ratio of said fluid gap Wg to rotor diameter 2Rr is greater than 1/10.

6. The blood pump as claimed in claim 5 wherein said ratio is within a range from 1/10 to 1/5.4.

7. The blood pump as claimed in claim 1 wherein said rotor includes an impeller housing having impeller blades for directing said entry of said blood at said inflow end, a rotor tail located at an opposite end of said rotor from said impeller housing, and a draw rod for connecting said impeller housing to said rotor tail with said rotor permanent magnets there between so as to form a draw-rod assembly.

8. The blood pump as claimed in claim 7 wherein said stator include stationary blades for directing said exit of said blood at said outflow end.

9. The blood pump as claimed in claim 8 wherein said first sensor coil is located adjacent said impeller blades and said second sensor coil is located adjacent said stationary blades.

10. The blood pump as claimed in claim 8 wherein said first and second sensor coils occupy peripheral spaces at opposite ends of said stator.

11. The blood pump as claimed in claim 8 wherein said first and second sensor coils are substantially cone shaped.

12. The blood pump as claimed in claim 8 wherein said stator includes a short housing end within which said stationary stator blades are formed.

13. A method of optimizing a magnetically-levitated blood pump, said method comprising:
providing a rotor for said blood pump including a radius Rr and a plurality of permanent magnet rings configured to increase rotor mass and for supercritical operation;
providing stator permanent magnets located on a stator, said stator permanent magnets corresponding to a portion of said plurality of permanent magnet rings, said stator permanent magnets and said plurality of permanent magnet rings forming magnetic bearings having a reduced stiffness;
forming a first permanent magnet bearing, to radially stabilize and center the rotor, formed from a first portion of said stator permanent magnets and a first corresponding portion of said rotor permanent magnet rings;
forming a second permanent magnet bearing, to radially stabilize and center the rotor, formed from a second portion of said stator permanent magnets and a second corresponding portion of said rotor permanent magnet rings;
positioning a motor magnet for interaction with a motor coil, and formed from a third corresponding portion of said rotor permanent magnet rings;
positioning at least one voice coil for interaction with a fourth corresponding portion of said rotor permanent magnet rings, said at least one voice coil configured to additionally interact with said first corresponding portion of said rotor permanent magnet rings to stabilize the rotor in an axial direction; and
forming a fluid gap Wg defined by a magnetic gap Sr minus the rotor radius Rr,
configuring said rotor and said stator to enable said reduced stiffness, wherein the supercritical operation of the rotor and the fluid gap Wg provides for the blood pump to be adapted for miniaturization and for minimally-invasive implantation,
wherein the blood pump includes an inflow end providing for entry of blood; an outflow end providing for exit of said blood; a first sensor coil located at a blood flow convergence adjacent said inflow end, and a second sensor coil located at a blood flow divergence adjacent said outflow end, the stator oriented in axial alignment with, and located between, the inflow end and the outflow end.

14. The method as claimed in claim 13 wherein said configuring step includes providing an annular blood gap formed between an outermost surface of said rotor and an innermost surface of said stator in accordance with a ratio of said annular blood gap to rotor diameter being greater than 1/10.

15. The method as claimed in claim 14 wherein said ratio is within a range from 1/10 to 1/5.4.

16. The method as claimed in claim 15 wherein said blood pump includes an outlet diameter at an outlet of said annular blood gap and said method further includes configuring said rotor to provide a ratio of rotor diameter to said outlet diameter of less than 2.

17. A method of optimizing a magnetically-levitated blood pump for supercritical operation, said method comprising:
providing a stator oriented in axial alignment with, and located between, an inflow end providing for entry of blood and an outflow end providing for exit of said blood, and including a plurality of stator permanent magnets, at least one voice coil, and a motor coil;
providing a rotor centered within said stator, including a plurality of rotor permanent magnets, the rotor configured for supercritical operation and to provide a ratio of rotor diameter to an outflow end diameter of less than 2; and
providing a first permanent magnet bearing and a second permanent magnet bearing, said first permanent magnet bearing arranged near said inflow end and formed from a first portion of said stator permanent magnets and a first corresponding portion of said rotor permanent magnets, said second permanent magnet bearing arranged near said outflow end and fo

Assignees

• Ricci Michael R
• Antaki James F
• Verkaik Josiah E
• Paden David B
• Snyder Shaun T
• Paden Bradley E
• Wu Jingchun
• Worldheart Corp
• Univ Carnegie Mellon

Inventors

• Ricci Michael R
• Antaki James F
• Verkaik Josiah E
• Paden David B
• Snyder Shaun T
• Paden Bradley E
• Wu Jingchun

Classifications

• Y10T29/49012

  Rotor · CPC title

• F16C32/0448

  by using the electromagnet itself as sensor, e.g. sensorless magnetic bearings · CPC title

• A61M1/1031

  Human Necessities · mapped topic

• A61M1/1015

  Human Necessities · mapped topic

• F16C2316/18

  Pumps for pumping blood · CPC title