Rotary pump with electromagnetic LCR bearing

• US 20050147512A1
• Filed: 10/01/2004
• Published: 07/07/2005
• Est. Priority Date: 10/03/2003
• Status: Abandoned Application

• Current Assignee: Cleveland Clinic Foundation, Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Cleveland Clinic Foundation, Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Inventors: Vitale, Nicholas G., Chapman, Peter A. Jr., Meeker, David C., Chen, Hsiang Ming, Smith, William A., Donahue, Arthur C.
• Application Number:
  US10/956,627
• Publication Number:
  US 20050147512A1
• Time in Patent Office: Days
• US Class Current: 417/423.120
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/216 including a rotating member acting on the blood, e.g. impeller
• CPC Class Codes: A61M 60/422 the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps
• CPC Class Codes: A61M 60/82 Magnetic bearings
• CPC Class Codes: F04D 13/0666 the motor being of the plane gap type
• CPC Class Codes: F04D 29/048 magnetic; electromagnetic
• CPC Class Codes: F16C 2316/18 Pumps for pumping blood
• CPC Class Codes: F16C 2360/44 Centrifugal pumps in general F04D
• CPC Class Codes: F16C 32/0412 for radial load mainly
• CPC Class Codes: F16C 32/0448 by using the electromagnet itself as sensor, e.g. sensorless magnetic bearings
• CPC Class Codes: F16C 32/0459 Details of the magnetic circuit
• CPC Class Codes: F16C 32/0485 with active support of three degrees of freedom
• CPC Class Codes: H02K 21/24 with magnets axially facing the armatures, e.g. hub-type cycle dynamos
• CPC Class Codes: H02K 7/09 with magnetic bearings
• CPC Class Codes: H02K 7/14 Structural association with mechanical loads, e.g. with hand-held machine tools or fans with fan or impeller for cooling the machine H02K9/06

Abstract

A pump (10) includes a housing (14) having a fluid inlet (26) and a fluid outlet (28). A rotor (12) is disposed within the housing (14) and rotatable about an axis (16) to move fluid from the fluid inlet (26) to the fluid outlet (28). A magnetic axial bearing (286) for supporting the rotor (12) includes an axial bearing target (70) disposed on the rotor and an axial bearing stator (130) disposed on the housing, the axial bearing stator including multiple stator poles (132a, 132b, 132c) each including a first coil portion wound in a first direction and a second coil portion wound in a second direction opposite the first direction.

Claims

1. A pump comprising:

a housing having a fluid inlet and a fluid outlet;

a rotor disposed within the housing and rotatable about an axis to move fluid from the fluid inlet to the fluid outlet; and

a magnetic axial bearing for supporting the rotor, the axial bearing comprising an axial bearing target disposed on the rotor and an axial bearing stator disposed on the housing, the axial bearing stator including multiple stator poles, each of the stator poles including a first coil portion wound in a first direction and a second coil portion wound in a second direction opposite the first direction.

2. The pump recited in claim 1, wherein the first and second coil portions are formed from a single length of wire.

3. The pump recited in claim 1, wherein the first direction is clockwise and second direction is counterclockwise.

4. The pump recited in claim 1, wherein each of the multiple stator poles is excited by an electrical phase of a multiple phase voltage source.

5. The pump recited in claim 1, wherein each of the multiple stator poles comprises an electromagnet having an inductance (L), the electromagnet being connected in series with a resistance (R), a capacitance (C), and a phase voltage source to form an LCR circuit for controlling the axial bearing.

6. The pump recited in claim 1, wherein the bearing stator is excitable to attract the axial bearing target and the rotor.

7. The pump recited in claim 1, wherein the bearing stator includes three stator poles, each stator pole including a first coil wound in a clockwise configuration and a the second coil wound in a counterclockwise configuration, each of the stator poles being excited by a corresponding electrical phase of a three phase voltage source.

8. The pump recited in claim 7, wherein the first and second coils are wound with a single length of wire.

9. The pump recited in claim 1, wherein the axial bearing stator comprises a strip of material wound in a cylindrical coil and machined to form a stator core including stator posts around which the first and second coils of each stator pole are wound.

10. The pump recited in claim 9, wherein the strip of magnetic material comprises one of a ferrite, powdered iron and laminated silicon steel material.

11. The pump recited in claim 1, further comprising:

a magnetic first radial bearing for exerting a force on the rotor in a first direction along the axis; and

a magnetic second radial bearing for exerting a force on the rotor in a second direction along the axis opposite the first direction;

the first and second radial bearings being adjustable to allow for adjusting the net axial force exerted on the rotor by the radial bearings independent of the radial stiffness of the radial bearings.

20. The pump recited in claim 1, wherein the axial bearing stator is excited by voltage superimposed on a voltage supplied to a motor stator of the pump.

12. A pump comprising:

a housing having a fluid inlet and a fluid outlet;

a rotor disposed within the housing and rotatable about an axis to move fluid from the fluid inlet to the fluid outlet;

a magnetic first radial bearing for exerting a force on the rotor in a first direction along the axis; and

a magnetic second radial bearing for exerting a force on the rotor in a second direction along the axis opposite the first direction;

the first and second radial bearings being adjustable to allow for independently adjusting the net axial force exerted on the rotor by the radial bearings and the radial stiffness of the radial bearings.

13. The pump recited in claim 12, wherein one of the first and second radial bearings is adjustable an axial distance toward the rotor and the other of the first and second radial bearings is adjustable the same axial distance away from the rotor to adjust the net axial force exerted on the rotor by the first and second radial bearings independent of the radial stiffness of the first and second radial bearings.

14. The pump recited in claim 13, wherein the first and second radial bearings are adjustable an equal axial distance toward the rotor to increase the radial stiffness of the first and second radial bearings independent of the net axial force exerted on the rotor by the first and second radial bearings.

15. The pump recited in claim 13, wherein the first and second radial bearings are adjustable an equal axial distance away from the rotor to vary the radial stiffness exerted of the first and second radial bearings independent of the net axial force exerted on the rotor by the first and second radial bearings.

16. The pump recited in claim 12, wherein the first radial bearing comprises a first magnetic ring supported on the housing facing a first side of the rotor and a second magnetic ring supported the housing facing a second side of the rotor, opposite the first side of the rotor, the first and second magnetic rings being adjustable along the axis to independently adjust the net axial force exerted on the rotor by the radial bearings and the radial stiffness of the radial bearings.

17. The pump recited in claim 16, wherein the first radial bearing further comprises a third magnetic ring on the first side of the rotor and the second radial bearing further comprises a fourth magnetic ring on the second side of the rotor, the first and third magnetic rings being arranged to attract each other, the second and fourth magnetic rings being arranged to attract each other.

18. The pump recited in claim 17, wherein the first, second, third and fourth magnetic rings are centered on the axis.

19. The pump recited in claim 17, wherein the magnetic rings are offset in order to oppose an average net hydraulic radial force exerted on the rotor by the fluid.

21. A pump comprising:

a housing having a fluid inlet and a fluid outlet;

a rotor disposed within the housing and rotatable about an axis to move fluid from the inlet to the outlet, the rotor comprising permanent magnets arranged on a first side of the rotor and a magnetically conductive disk arranged on a second side of the rotor opposite the first side of the rotor;

a motor stator arranged on the housing to interact with the permanent magnets on the rotor;

at least one electromagnet arranged on the housing to interact with the magnetically conductive disk on the rotor; and

at least one ring magnet arranged on at least one of the first and second sides of the rotor;

at least one ring magnet arranged on the housing to magnetically interact with the at least one ring magnet on the rotor.

22. The pump recited in claim 21, wherein the interaction between the motor stator and the permanent magnets on the rotor, and the interaction between the at least one electromagnet and the magnetically conductive disk on the rotor combine to suspend the rotor on the axis.

23. The pump recited in claim 21, wherein the electromagnet comprises a stator, the stator comprising one of an oriented and a non-oriented surface insulated electromagnetic lamination material that is spiral wound.

24. The pump recited in claim 23, wherein comprising pole shapes are cut into the spiral wound material so as to be free from short circuits between layers of the spiral wound material.

25. The pump recited in claim 21, wherein the at least one electromagnet comprises coils having a common ground.

26. The pump recited in claim 21, wherein the at least one electromagnet comprises a plurality of coils wound in alternating directions.

27. The pump recited in claim 26, wherein adjacent pairs of the coils are wound with a single length of wire.

28. The pump recited in claim 26, wherein the coils have an inductance L and are connected with a resistance R and a capacitance C.

29. The pump recited in claim 26, wherein the coils are excited with an alternating current.

30. The pump recited in claim 29, wherein each coil is excited with a different frequency of alternating current.

31. The pump recited in claim 29, wherein the magnitude of the alternating current is used as an indicator of rotor position.

32. The pump recited in claim 29, wherein two different frequencies are used to excite the coils, one of the frequencies during start-up, and another of the frequencies during steady state operation.

33. The pump recited in claim 26, wherein the coils have an inductance that varies with the motion of the rotor, the current flow through the coils varying with the inductance of the coils.

34. The pump recited in claim 33, wherein the changes in current flow result in changes in electromagnetic force that oppose the rotor motion.

35. The pump recited in claim 21, wherein rotor vibrations are dampened by pumped fluid between the rotor and the motor stator and between the rotor and the electromagnet.

36. The pump recited in claim 35, wherein close clearances between the rotor and motor stator and between the rotor and the electromagnet impede fluid flow to increase damping effects.

37. The pump recited in claim 36, wherein one of the close clearances is between the adjacent radii at an inlet of the rotor.

38. The pump recited in claim 21, wherein the ring magnets on the rotor and the ring magnets on the housing are positioned symmetrically with each other.

39. The pump recited in claim 38, wherein the ring magnets on the first side of the rotor, ring magnets on the second side of the rotor, ring magnets on the motor stator, and ring magnets on the electromagnet are positioned symmetrically with each other.

40. The pump recited in claim 38, wherein at least one of the ring magnets on the motor stator and the electromagnet are adjustable to tune radial and axial components of force.

41. The pump recited in claim 21, wherein at least one of the ring magnets is adjustable to tune radial and axial components of force.

42. The pump recited in claim 21, wherein the housing comprises a sealed cartridge with separately removable and reusable motor and stator housings.

43. The pump recited in claim 42, further comprising at least one sealing wall that has a mechanical stiffness derived from a combination of radial tension and back support from the removable stator housings.

44. The pump recited in claim 21, wherein the magnetically conductive disk on the rotor is formed from a spiral wound lamination material.

45. The pump recited in claim 21, further comprising a projection for directing flow into the rotor flow path, the projection forming a stop point for excessive axial rotor travel.

46. A pump comprising:

a housing having a fluid inlet and a fluid outlet;

a rotor disposed within the housing and rotatable about an axis to move fluid from the inlet to the outlet;

a motor arranged to cause rotation of the rotor;

at least one electromagnet arranged to interact magnetically with material in the rotor, the electromagnet comprising a stator formed from a spiral wound lamination material.

47. A pump comprising:

a housing having a fluid inlet and a fluid outlet;

a rotor disposed within the housing and rotatable about an axis to move fluid from the inlet to the outlet;

a motor arranged to cause rotation of the rotor;

at least one electromagnet arranged to interact magnetically with material in the rotor, the electromagnet comprising an even number of poles, adjacent poles being wound in opposite directions.

48. The pump recited in claim 47, wherein adjacent poles are arranged in pairs and are wound with a single length of wire.

49. A pump comprising:

a housing having a fluid inlet and a fluid outlet;

a rotor disposed within the housing and rotatable about an axis to move fluid from the inlet to the outlet;

a motor arranged to cause rotation of the rotor;

at least one electromagnet arranged to interact magnetically with material in the rotor, the material comprising a disk of spiral wound magnetic alloy material.

50. A method for magnetically supporting a pump rotor in a housing for rotation about an axis, the method comprising the steps of:

providing an axial bearing target on the rotor;

providing an axial bearing stator on the housing, the axial bearing stator including multiple stator poles each including a first coil portion and a second coil portion;

winding the first coil portion in a first direction; and

winding the second coil portion in a second direction opposite the first direction.

51. A method for magnetically supporting a pump rotor in a housing for rotation about an axis, the method comprising the steps of:

providing a magnetic first radial bearing for exerting a force on the rotor in a first direction along the axis;

providing a magnetic second radial bearing for exerting a force on the rotor in a second direction along the axis opposite the first direction; and

adjusting the axial positions of the first and second radial bearings to independently adjust the net axial force exerted on the rotor by the first and second radial bearings and the radial stiffness of the first and second radial bearings.

52. The method recited in claim 51, further comprising the steps of adjusting one of the first and second radial bearings an axial distance to increase its axial pull on the rotor and adjusting the other of the first and second magnetic rings the same axial distance to decrease its axial pull on the motor to adjust the net axial force exerted on the rotor by the first and second radial bearings independent of the radial stiffness of the first and second radial bearings.

53. The method recited in claim 51, further comprising the steps of adjusting the first and second radial bearings an axial distance toward the rotor to increase the radial stiffness of the first and second radial bearings independent of the net axial force exerted on the rotor by the first and second radial bearings.

54. The method recited in claim 51, further comprising the steps of adjusting the first and second radial bearings an axial distance away from the rotor to decrease the radial stiffness of the first and second radial bearings independent of the net axial force exerted on the rotor by the first and second radial bearings.