Frontal magnet coupling with integrated magnetic bearing load relief

• US 4,767,378 A
• Filed: 07/29/1986
• Issued: 08/30/1988
• Est. Priority Date: 08/01/1985
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Obermann, Peter
• Primary Examiner(s): Stodola, Daniel P.
• Application Number:
  US06/891,451
• Time in Patent Office: 763 Days
• Field of Search: 417/420, 464/29, 623/3
• US Class Current: 464/29
• CPC Class Codes: A61M 2205/3515 using magnetic means
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: B23H 11/00 Auxiliary apparatus or details, not otherwise provided for
• CPC Class Codes: F04C 15/0042 Systems for the equilibration of forces acting on the machines or pump interstice adjustment other than by fluid pressure F01C21/102
• CPC Class Codes: F04C 15/0069 Magnetic couplings
• CPC Class Codes: F04D 29/041 Axial thrust balancing
• CPC Class Codes: F16C 2316/10 in medical appliances, e.g. in diagnosis, dentistry, instruments, prostheses, medical imaging appliances
• CPC Class Codes: F16C 39/063 Permanent magnets
• CPC Class Codes: H02K 49/108 with an axial air gap
• CPC Class Codes: H02K 5/128 using air-gap sleeves or air-gap discs
• CPC Class Codes: H02K 7/09 with magnetic bearings

Abstract

A frontal magnetic rotational coupling for transmitting torque from a first enclosure to a second enclosure, said enclosures being hermetically separated from each other by an isolating wall. A plate affixed directly above a magnet attached to a rotatable shaft in one enclosure of the coupling is employed to magnetically provide bearing load relief. Axial force exerted upon the magnet from the other enclosure is compensated for by the magnetic field of the magnet itself, due to the return flux path provided by the plate. A miniaturized form of construction results which is of particular advantage when the frontal magnetic rotational coupling is used, for example, in an implantable medication dispensing device.

Claims

1. A frontal magnetic coupling provided with at least one magnet for the transmission of torques or forces from a first to a second enclosure of a housing, said enclosures being separated from each other by means of an isolating wall, comprising:

a driving element coupled for rotation in said first enclosure;

a driven element coupled for rotation in said second enclosure and axially aligned with said driving element;

a magnet having a contact surface mechanically coupled to one of said driving and said driven elements;

an element of magnetizable material coupled to the other one of said driving and said driven elements; and

a stationary plate of magnetizable material spaced above the contact surface of said magnet so as to form an air gap therebetween, said plate providing a return path for the magnetic flux of said magnet and thereby providing axial magnetic forces across said air gap which compensates and provides a magnetic bearing load relief of axial magnetic forces between said magnet and said element of magnetizable material.

2. A frontal magnetic coupling according to claim 1, wherein said plate is mechanically coupled to said housing.

3. A frontal magnetic coupling according to claim 2, wherein said housing forms the enclosure for one of said driving and said driven elements that are associated with the magnetic coupling and wherein one surface of the housing is designed to form the plate.

4. A frontal magnetic coupling according to claim 3, wherein:

said plate is provided with a clearance hole for the passage of a drive shaft.

5. A front magnetic coupling according to claim 3, wherein:

said element of magnetizable material is a magnet arranged to axially attract said first mentioned magnet, said first and second mentioned magnets being located in said first and second enclosures, respectively; and

the length of said air gap having an order of magnitude that is one half the distance between said two magnets separated by said isolating wall.

6. A frontal magnetic coupling according to claim 5, wherein:

the length of said air gap may deviate up to 50% from the distance between said magnets separated by the isolating wall.

7. A frontal magnetic coupling according to claim 3, wherein:

said plate is provided with a clearance hole for the passage of a driven shaft.

8. A frontal magnetic coupling according to claim 2, wherein said housing forms a driven enclosure that is associated with the magnetic coupling and wherein a front surface of the driven enclosure forms the plate.

9. A frontal magnetic coupling according to claim 2, wherein said housing forms a driving enclosure that is associated with the magnetic coupling and wherein a front surface of the driving enclosure forms the plate.

10. A frontal magnetic coupling according to claim 2, wherein:

said element of magnetizable material is a magnet arranged to axially attract said first mentioned magnet, said first and second mentioned magnets being located in said first and second enclosures, respectively; and

the length of said air gap having an order of magnitude that is one half the distance between said two magnets separated by said isolating wall.

11. A frontal magnetic coupling according to claim 10, wherein:

the length of said air gap may deviate up to 50% from the distance between said magnets separated by the isolating wall.

12. A frontal magnetic coupling according to claim 11, wherein:

said stationary plate is composed of a soft magnetizable material.

13. A frontal magnetic coupling according to claim 12, wherein:

said magnetizable material is nickel or soft iron.

14. A frontal magnetic coupling according to claim 1 wherein said one of said driving and said driven elements comprises:

a magnet support plate of non-magnetic material

said magnet being affixed to said magnet support plate; and

a shaft affixed to said magnet support plate, said shaft passing through a clearance hole in said stationary plate

and said air gap being provided beteen the magnet support plate and the stationary plate.

15. A frontal magnetic coupling according to claim 14, wherein:

at least two magnets are attached diagonally opposite to each other on said magnet support plate, said two magnets being magnetized with opposing polarities.

16. A frontal magnetic coupling according to claim 15 wherein said isolating wall comprises a portion of a hermetic seal between said first and second enclosures.

17. A frontal magnetic couplng according to claim 1, wherein each of said driving and said driven elements comprise:

a magnet support plate of non-magnetic material, said magnet being affixed to said magnet support plate; and

a shaft affixed to said magnet support plate; and

a stationary plate of magnetizable material spaced above said magnet support plate so as to form an air gap therebetween, said shaft passing through a clearance hole in said stationary plate.

18. A frontal magnetic coupling according to claim 17, wherein:

at least two magnets are attached diagonally opposite to each other on said magnet support plate, said two magnets being magnetized with opposing polarities.

19. A frontal magnetic coupling according to claim 1, wherein:

said element of magnetizable material is a magnet arranged to axially attract said first mentioned magnet, said first and second mentioned magnets being located in said first and second enclosures, respectively; and

the length of said air gap having an order of magnitude that is one half the distance between said two magnets separated by said isolating wall.