Electromagnetic induction device

• US 20010024152A1
• Filed: 03/23/2001
• Published: 09/27/2001
• Est. Priority Date: 03/24/2000
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Tabuchi Electric Company Limited
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Tabuchi Electric Company Limited
• Inventors: Yamagata, Fumiaki, Kambara, Seiji, Takashige, Yutaka, Masuda, Shinichi, Miyazaki, Sinobu, Souma, Hideaki
• Granted Patent: US 6,587,023 B2
• Time in Patent Office: Days
• US Class Current: 336/181
• CPC Class Codes: H01F 27/306 Fastening or mounting coils or windings on core, casing or other support
• CPC Class Codes: H01F 30/10 Single-phase transformers H01F30/16 takes precedence
• CPC Class Codes: H05B 6/36 Coil arrangements

Abstract

An electromagnetic induction device having a flat configuration that requires a relatively small space for installation on a circuit substrate includes a flat bobbin (1T) having a length (D1) smaller than a radial size (D2) thereof has primary and secondary windings (11, 12) wound thereon. This bobbin (1T) has coaxially aligned throughholes (20, 22) defined therein into which core legs (24T and 24T) of generally T-shaped first and second core pieces (23T, 23T) are inserted from opposite directions, respectively. Respective core arms (25T, 25T) of the first and second core pieces (23T, 23T) extend parallel to each other.

Claims

1. An electromagnetic induction device which comprises:

a core assembly for defining a magnetic circuit, said core assembly including generally T-shaped or L-shaped first and second core pieces;

a generally flat bobbin having an axial width and a radial size, the axial width being smaller than the radial size, said bobbin having a bore defined therein so as to extend in an axial direction of the bobbin; and

a winding member mounted on the bobbin;

wherein the core legs of the first and second core pieces are inserted into the bore of the flat bobbin while the core arms of the first and second core pieces extend parallel to each other.

2. The electromagnetic induction device as claimed in

claim 1

, wherein the winding member includes primary and secondary windings mounted on the bobbin in axially spaced relation to each other and wherein respective free ends of the core legs of the first and second core pieces confront with each other to define a gap therebetween.

3. The electromagnetic induction device as claimed in

claim 2

, wherein a coupling coefficient between the primary and secondary windings is set to a value within the range of 0.6 to 0.8.

4. The electromagnetic induction device as claimed in

claim 1

, wherein the winding member includes primary and secondary windings mounted on the bobbin in axially spaced relation to each other;

wherein the primary winding has lead lines extending from respective opposite ends thereof, each of said lead lines of the primary winding being fitted with a terminal member adapted to be connected with a terminal piece, mounted on a circuit substrate, by screwing or insertion, and wherein the secondary winding has opposite ends connected with respective pin terminals fixedly secured to the bobbin and adapted to be inserted into the circuit substrate.

5. The electromagnetic induction device as claimed in

claim 1

, wherein at least a portion of the winding member is an electric wire coated with a thermally fusible material that is wound into a uniformly layered coil block and is subsequently caked into a layered coil block by heating to fuse the thermally fusible material, said layered coil block being mounted on the bobbin.

6. The electromagnetic induction device as claimed in

claim 1

, further comprising a secondary circuit substrate;

wherein the bobbin is integrally formed with a substrate mount for supporting the secondary circuit substrate; and

wherein the winding member comprises primary and secondary windings, said primary winding having opposite lead lines that are connected with a primary circuit substrate and said secondary winding being connected with the secondary circuit substrate.

7. The electromagnetic induction device as claimed in

claim 6

, wherein the substrate mount is positioned laterally of the bobbin and radially outwardly of at least one of the primary and secondary windings.

8. The electromagnetic induction device as claimed in

claim 6

, wherein the substrate mount is formed in a collar that defines one axial end of the bobbin, and is positioned axially outwardly of the primary and secondary windings.

9. The electromagnetic induction device as claimed in

claim 1

, wherein the bobbin comprises a plurality of bobbin pieces defined by dividing the bobbin in a direction axially thereof and wherein each of the core pieces is embedded in the corresponding bobbin piece.

10. The electromagnetic induction device as claimed in

claim 9

, wherein at least a portion of one of opposite surfaces of each of the first and second core pieces where no corresponding core arm is formed is exposed to an outside.

11. The electromagnetic induction device as claimed in

claim 1

, wherein the bobbin has at least one winding groove defined therein for receiving the winding member wound therein and comprises a plurality of bobbin pieces defined by dividing the bobbin in a direction axially thereof;

and

wherein the plural bobbin pieces are connected together such that a groove width of the winding groove straddling the neighboring bobbin pieces is variable.

12. The electromagnetic induction device as claimed in

claim 11

, wherein the bobbin comprises at least first and second bobbin pieces each including a hollow cylindrical body having a throughhole defined therein, said bore being defined by the respective throughholes in the bobbin pieces when the respective hollow cylindrical bodies of the first and second bobbin pieces are coaxially aligned with each other;

said bobbin pieces being assembled together to complete the bobbin with the hollow cylindrical body in the first bobbin piece inserted into the hollow cylindrical body in the second bobbin piece;

wherein one of an inner peripheral surface of the hollow cylindrical body in the first bobbin piece and an outer peripheral surface of the hollow cylindrical body in the second bobbin piece is formed with an engagement projection, and the other of the inner peripheral surface of the hollow cylindrical body in the first bobbin piece and the outer peripheral surface of the hollow cylindrical body in the second bobbin piece is formed with an axially extending guide groove and a plurality of circumferentially extending engagement grooves communicated with the guide groove and spaced a distance from each other in a direction axially of the bobbin; and

wherein when the hollow cylindrical bodies are connected together one inserted into the other, said engagement projection is guided along the guide groove in the axial direction and is subsequently engaged in one of the engagement grooves upon relative displacement of the hollow cylindrical bodies in the circumferential direction.