Reducing inductive heating

• US 9,325,183 B2
• Filed: 12/21/2012
• Issued: 04/26/2016
• Est. Priority Date: 12/21/2012
• Status: Active Grant

• Current Assignee: Piece Future Pte., Ltd.
• Original Assignee: Nokia Technologies Oy (Nokia Corporation)
• Inventors: Backman, Juha Reinhold
• Primary Examiner(s): Levin, Naum B
• Application Number:
  US13/724,672
• Publication Number:
  US 20140176058A1
• Time in Patent Office: 1,222 Days
• US Class Current: 1/1
• CPC Class Codes: H01F 2027/348 Preventing eddy currents
• CPC Class Codes: H01F 27/38 Auxiliary core members; Auxiliary coils or windings
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction
• CPC Class Codes: H04R 9/022 Cooling arrangements
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

An apparatus including a magnet assembly having at least two magnet assembly components; and an eddy current heating reduction system configured to reduce heating of the magnet assembly by magnetic fields. The eddy current heating reduction system includes electrical insulation between the at least two magnet assembly components, and includes at least one of the at least two magnet assembly components having a divided current loop area at least two spaced subsections.

Claims

1. An apparatus comprising an audio transducer having a magnet assembly, wherein the magnet assembly comprises:

at least two magnet assembly components; and

an eddy current heating reduction system configured to reduce heating of the magnet assembly by magnetic fields, where the eddy current heating reduction system comprises electrical insulation sandwiched between the at least two magnet assembly components, and by providing at least one of the at least two magnet assembly components with a divided current loop area having at least two planar spaced subsections formed by at least one cut or gap, where the at least two planar spaced subsections are aligned in a common plane forming a majority of the divided current loop area in the common plane.

2. An apparatus as in claim 1 where the at least two magnet assembly components comprise at least one magnet, a first pole piece connected to a first side of the at least one magnet and a second pole piece connected to an opposite second side of the at least one magnet, and where the first pole piece is a one-piece member, where the at least one cut or gap comprises multiple cuts in the one-piece member which form at least some of the at least two spaced subsections in the first pole piece.

3. An apparatus as in claim 2 where the first pole piece comprises at least one of:

at least two of the spaced subsections connected by a relatively smaller bridge connection section, or

at least four of the spaced subsections connected by a relatively smaller bridge connection section.

4. An apparatus as in claim 1 where the at least two magnet assembly components comprise at least one magnet, a first pole piece connected to a first side of the at least one magnet and a second pole piece connected to an opposite second side of the at least one magnet, and where the second pole piece comprises a magnet assembly pot having a recess, where the at least one magnet is located in the recess, and where the second pole piece is a one piece member, where the at least one cut or gap comprises multiple cuts in the one piece member of the second pile piece which form at least some of the spaced subsections in the second pole piece.

5. An apparatus as in claim 4 where the magnet assembly pot comprises at least two of the spaced subsections connected by a relatively smaller bridge connection section.

6. An apparatus as in claim 5 where the magnet assembly pot comprises at least four of the spaced subsections connected by a relatively smaller bridge connection section.

7. An apparatus as in claim 1 where the at least two assembly components comprise at least one magnet, a first pole piece connected to a first side of the at least one magnet and a second pole piece connected to an opposite second side of the at least one magnet, and where the first pole piece is a top plate which comprises multiple spaced members which are electrically isolated from each other and which form at least some of the spaced subsections.

8. An apparatus as in claim 1 where the at least two magnet assembly components comprise at least one magnet, a first pole piece connected to a first side of the at least one magnet and a second pole piece connected to an opposite second side of the at least one magnet, and where the second pole piece comprises multiple spaced members which are electrically isolated from each other and which form at least some of the at least two spaced subsections.

9. An apparatus as in claim 1 where the at least two magnet assembly components comprise at least two magnets and a first pole piece, where the at least two magnets are mechanically connected to each other by the first pole piece.

10. An apparatus as in claim 1 where the at least two magnet assembly components comprise a first magnet, where the at least one cut or gap comprises multiple cuts in the first magnet that form the divided current loop area on the first magnet with multiple spaced magnet subsections.

11. An apparatus as in claim 1 where the at least two magnet assembly components comprise at least one magnet, a first pole piece connected to a first side of the at least one magnet and a second pole piece connected to an opposite second side of the at least one magnet, and where the first and second pole pieces are connected to the at least one magnet by the electrical insulation which comprises electrically insulating adhesive.

12. An apparatus as in claim 1 comprising means for reducing eddy current heating of at least one of the magnet assembly components by magnetic fields.

13. A device comprising:

a housing;

a rechargeable battery in the housing;

an induction charging system in the housing coupled to the rechargeable battery; and

the apparatus as in claim 1 in the housing.

14. A method comprising:

providing at least one magnet;

connecting at least one pole piece to the at least one magnet, where the at least one pole piece is electrically insulated from the at least one magnet by electrical insulation sandwiched between the at least one pole piece and the at least one magnet, and where the at least one pole piece and/or the at least one magnet comprises a divided eddy current loop area having multiple planar spaced subsections formed by at least one cut or gap, where the multiple planar spaced subsections are aligned in a common plane forming a majority of the divided current loop area in the common plane to reduce eddy current heating of the at least one pole piece and/or the at least one magnet by magnetic fields; and

constructing an audio transducer comprising a magnet assembly, the magnet assembly including the at least one magnet with the connected at least one pole piece.

15. A method as in claim 14 where the at least one pole piece:

is provided with a first pole piece provided as a top plate comprising;

a one-piece member, where the at least one cut or gap comprises multiple cuts in the one piece member which form at least some of the multiple spaced subsections in the first pole piece, or

multiple spaced members which are electrically isolated from each other and which form at least some of the multiple spaced subsections, and/or

is provided with a second pole piece comprising a magnet assembly pot having a recess, where the at least one magnet is located in the recess, where the magnet assembly pot comprises;

a one piece member, where the at least one cut or gap comprises multiple cuts in the one piece member of the magnet assembly pot which form at least some of the multiple spaced subsections in the second pole piece, or

multiple spaced members which are electrically isolated from each other and which form at least some of the multiple spaced subsections.

16. A method as in claim 14 comprising connecting a first pole piece of the at least one pole piece to a first side of the at least one magnet and connecting a second pole piece of the at least one pole piece to an opposite second side of the at least one magnet, and where the first and second pole pieces are connected to the at least one magnet by the electrical insulation which comprises electrically insulating adhesive.

17. A method as in claim 14 where the at least one magnet comprises at least two magnets, and the method comprises mechanically connecting the at least two magnets to each other by the at least one pole piece.

18. A method as in claim 14 wherein the at least one cut or gap comprises multiple cuts formed in a first one of the at least one magnet that form the divided current loop area on the first magnet with multiple spaced magnet subsections.

19. An apparatus comprising:

a housing;

a rechargeable battery in the housing;

an induction charging system in the housing coupled to the rechargeable battery; and

an audio transducer with a magnet assembly in the housing, where the magnet assembly comprises at least one magnet and a first pole piece connected to the at least one magnet, where the first pole piece is electrically insulated from the at least one magnet by electrical insulation sandwiched between the at least one magnet and the first pole piece, and where the first pole piece comprises a divided eddy current loop area having at least two planar spaced subsections formed by at least one cut or gap, where the at least two planar spaced subsections are aligned in a common plane forming a majority of the divided current loop area in the common plane to reduce eddy current heating of the first pole piece by magnetic fields used for recharging the battery by the induction charging system.

20. An apparatus as in claim 19 where the magnet assembly comprises the first pole piece connected to a first side of the at least one magnet and a second pole piece connected to a second side of the at least one magnet, where the first pole piece forms a top plate of the magnet assembly, where the second pole piece comprises a magnet assembly pot having a recess, where the at least one magnet is located in the recess, and where the second pole piece comprises a divided eddy current loop area having multiple spaced subsections to reduce eddy current heating of the second pole piece by the magnetic fields used for recharging the battery by the induction charging system.