JP2016139672A - Current transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current transformer capable of setting a current transformation ratio larger.SOLUTION: In the current transformer formed by winding a secondary coil around a magnetic core 2, the magnetic core 2 includes a plurality of magnetic pieces 4 and a coupling member 5 provided at an end surface of each of the magnetic pieces 4, and is formed in an annular shape by mutually connecting the coupling members 5.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a current transformer. More specifically, the present invention relates to a current transformer in which a secondary winding is wound around a magnetic core.

  Conventionally, a current transformer is known in which a secondary winding is wound around a magnetic core made of a magnetic material. Some magnetic cores have an annular shape, that is, an endless shape such as an annular shape or a polygonal shape. It is not easy to wind the secondary winding around the magnetic core having such an endless shape. Therefore, in Patent Document 1, a current transformer is obtained as follows using a material that is easily deformed as the material of the magnetic core. That is, first, as shown in FIG. 7, one portion of the magnetic core 11 having an endless shape is cut along the cutting line 13. Next, the cut magnetic core 11 (hereinafter, “cut magnetic core” is referred to as “cutting material”) is deformed so that one cut end and the other cut end are separated from each other. The pre-wound secondary winding 12 is then inserted into the cutting material from either cut end of the cutting material. The cutting material is then deformed to its original shape. Thereafter, one cut end and the other cut end of the cutting material are welded to form an endless magnetic core 11, and a current transformer 10 in which the secondary winding 12 is wound around the magnetic core 11 is obtained. .

  Thus, in patent document 1, since the secondary winding previously wound from the cutting | disconnection edge part of cutting material is inserted, compared with winding to a secondary winding to an endless thing, a magnetic body core A current transformer in which a secondary winding is wound on can be obtained more easily.

US Pat. No. 6,335,673

  In the above-mentioned patent document 1, one cutting end of the cutting material and the other cutting end are welded because the cutting material is easily deformed, so that one cutting end of the cutting material and the other cutting end are cut. This is because the gap width between the ends cannot be maintained at a desired value, thereby causing variations in the performance of the current transformer.

  However, when welding one cut end of the cutting material and the other cut end, it is necessary to expose the peripheral portion of the portion to be welded greatly. For this reason, it becomes difficult to provide the secondary winding over the entire length of the cutting material, and it becomes difficult to configure a current transformer having a larger current transformation ratio.

  This invention is made | formed in view of said situation, and it aims at providing the current transformer which can set a current transformation ratio larger.

  In order to achieve the above object, a current transformer according to the present invention is a current transformer in which a secondary winding is wound around a magnetic core, wherein the magnetic core includes a plurality of magnetic body pieces and each magnetic body. A connecting member provided on an end surface of the piece, and the connecting member is connected to each other to form an annular shape.

  In the current transformer, the present invention further includes a case for holding the magnetic body piece formed so as to cover the end face of the magnetic piece, and the portion of the case facing the end face of the magnetic piece is the A connecting member is formed.

  According to the present invention, in the above-described current transformer, one of the connecting members adjacent to each other by the connection has an engagement piece protruding toward the other connection member, and the other connection member is the engagement member. It has the engagement recessed part engaged with a joining piece, It is characterized by the above-mentioned.

  According to the present invention, a magnetic core in which a plurality of magnetic body pieces are connected in a ring shape with a connecting member provided on the end face of the magnetic body piece is obtained. For this reason, for each of the plurality of magnetic body pieces, a magnetic body piece in which a secondary winding is wound over substantially the entire length of each magnetic body piece is manufactured, and by connecting these plurality of magnetic body pieces, A current transformer having more secondary windings can be obtained. Thereby, the current transformation ratio can be set larger.

FIG. 1 is a perspective view of a current transformer which is an embodiment of the present invention. FIG. 2 is an exploded perspective view of the current transformer in which the secondary winding is not wound in the current transformer of FIG. 1. FIG. 3 is an enlarged perspective view of a main part of the current transformer in which the secondary winding is not wound in the current transformer of FIG. 1. FIG. 4 is a schematic diagram for explaining a connected state of magnetic pieces in the current transformer of FIG. 1. FIG. 5 is a perspective view of the current transformer illustrating a state before the magnetic pieces are connected. FIG. 6 is a perspective view of a case in a current transformer which is another embodiment of the present invention. FIG. 7 is a schematic diagram of a conventional current transformer.

  Hereinafter, an embodiment of a current transformer according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a current transformer which is an embodiment of the present invention. This current transformer 1 includes an annular magnetic core 2 and a secondary winding 3 disposed so as to be wound around the magnetic core 2. The magnetic core 2 is formed into an annular shape by connecting two semi-circular magnetic pieces 4 (see FIG. 2) by a connecting member 5 (see FIG. 2).

  As shown in FIG. 2, the magnetic piece 4 is configured by laminating a plurality of magnetic bodies 4a. Each magnetic body 4a is formed of a magnetic material such as iron and is formed in a semi-annular plate shape.

  The connecting member 5 is a plate-like member having a size that covers the end surface of the magnetic piece 4 and is configured as a part of the case 6 that houses the magnetic piece 4. That is, the case 6 is formed so as to cover both circumferential end surfaces, inner circumferential surface, outer circumferential surface and bottom surface of the magnetic piece 4, and the end surface portions 6 a and 6 a of the case 6 covering both circumferential end surfaces are respectively A connecting member 5 is provided. The case 6 includes, in addition to the end surface portions 6a and 6a, an inner side surface portion 6b, an outer side surface portion 6c, and a bottom surface portion 6d that respectively cover the inner peripheral surface, the outer peripheral surface, and the bottom surface. A region surrounded by the end surface portions 6 a and 6 a, the inner side surface portion 6 b, the outer side surface portion 6 c and the bottom surface portion 6 d substantially matches the outer shape of the magnetic piece 4, and that region forms a storage space for the magnetic piece 4. The top surface portion of the case 6 is opened, and the magnetic piece 4 is accommodated in the case 6 through this opening.

  A cover 7 is provided on the top surface of the case 6. The cover 7 prevents the positional deviation in the axial direction of the magnetic piece 4 accommodated in the case 6 when the center of the annular magnetic core 2 is used as an axis. The cover 7 has a semi-annular shape so as to cover the opening of the top surface portion. Such a cover 7 is fixed to the top surface portion of the case 6 with an adhesive.

  As shown in FIGS. 3 and 4, the connecting member 5 includes an engagement piece 8 and an engagement recess 9. The engaging piece 8 is made of a plate-like member, and is integrally formed on the inner ring side of the end surface portion 6 a of the case 6. The engaging piece 8 protrudes toward the end surface portion 6a of the adjacent case 6 by the connection, and the protruding tip is bent toward the outer ring side. The engagement recess 9 is formed on the inner ring side of the end surface portion 6 a of the case 6 at a position closer to the bottom surface than the engagement piece 8. The engaging recess 9 is a notch portion in which the end surface portion 6a is notched in a rectangular parallelepiped shape. The notch is formed with a recess recessed in a rectangular parallelepiped shape.

  An engagement piece 8 and an engagement recess 9 are also formed on the outer ring side of the end surface portion 6 a of the case 6. The projecting tip of the engagement piece 8 on the outer ring side is bent toward the inner ring side. The engagement recess 9 is formed at a position on the upper surface side of the engagement piece 8. In the connection member adjacent to the connection member 5 shown in FIG. 3, the engagement recess 9 and the engagement piece 8 are formed at positions corresponding to the engagement piece 8 and the engagement recess 9 of the connection member 5 in FIG. ing.

  Next, the assembly procedure of the current transformer 1 according to the present embodiment will be described. First, the magnetic piece 4, the case 6, and the cover 7 are prepared. Next, the magnetic piece 4 is housed in the case 6, and the cover 7 is put on the top surface portion of the case 6 to fix the cover 7. Next, the secondary winding 3 is wound around the magnetic piece 4 from above the case 6 and the cover 7 by a winding machine. Thus, the magnetic piece 4 around which the secondary winding is wound is obtained. The magnetic piece 4 around which the secondary winding is wound is produced by the same procedure. Next, the magnetic pieces 4 and 4 around which the secondary winding 3 is wound are arranged so that their end faces face each other as shown in FIG. Next, the end faces of the magnetic pieces 4 and 4 are butted together. Then, the engaging piece 8 of the connecting member 5 provided on one magnetic piece 4 is inserted into the engaging recess 9 of the connecting member 5 provided on the other magnetic piece 4. The engagement piece 8 inserted into the engagement recess 9 is caught at the recess of the engagement recess 9 at the bent portion at the tip. As a result, the engaging piece 8 engages with the engaging recess 9 and the magnetic pieces 4 and 4 are connected by the connecting member 5 to obtain the current transformer 1 as shown in FIG.

  As described above, the magnetic core 2 provided in the current transformer 1 of the present embodiment is configured by connecting the two magnetic pieces 4 forming a semicircular ring with the connecting member 5. For this reason, the secondary winding 3 is wound over substantially the entire length of each magnetic piece 4 before the magnetic piece 4 is connected, and then the magnetic piece 4 is connected to the vicinity of the connecting portion of the magnetic core 2. Can also wind the secondary winding 3. Thereby, the current transformer 1 in which the secondary winding 3 is wound in a toroidal shape over substantially the entire circumference of the magnetic core 2 can be obtained.

  In assembling the current transformer 1 as described above, the annular magnetic core 2 can be produced without requiring welding as in the prior art. Further, in manufacturing the magnetic piece 4 around which the secondary winding 3 is wound, the secondary winding 3 is wound around the magnetic piece 4 in the same manner as the winding of the solenoid-shaped coil. The structure of the winding machine can be made simpler than winding the secondary winding around the object. Even when the small current transformer 1 is manufactured, the secondary winding 3 can be wound around the magnetic piece 4 by using a winding machine. Therefore, the current transformer 1 can be produced at a low cost in a short time, and the productivity can be improved.

  In addition, the current transformer 1 according to the present embodiment includes a case 6 that holds the magnetic piece 4 formed so as to cover the end face of the magnetic piece 4 and is opposed to the end face of the magnetic piece 4. A portion 6 forms a connecting member 5. Since the magnetic piece 4 is held by the case 6, the shape of the magnetic core produced by connecting the magnetic pieces 4 becomes more stable. Further, by using the case 6 having an area that substantially matches the outer shape of the magnetic piece 4 as a storage space for the magnetic piece 4, it is difficult for the magnetic piece 4 to be misaligned. The shape of the magnetic core produced by coupling is further stabilized.

  Moreover, in the current transformer 1 of this Embodiment, the end surface part 6a of case 6 which is a structural member of the connection member 5 is formed in plate shape with substantially constant thickness, The outer surface is processed into a flat surface. Therefore, as shown in FIG. 4, the end surface of the magnetic piece 4 and the inner surface of the end surface portion 6a of the case 6 are in surface contact, and the outer surfaces of the end surface portions 6a of the case 6 adjacent to each other by the connection are in surface contact. Then, the magnetic pieces 4 and 4 are connected. Thereby, a more stable connection state is realized.

  By selecting a material having a lower magnetic permeability than the magnetic body forming the magnetic piece 4 as the material of the connecting member 5, the connecting member 5 can be configured as a gap forming member. The gap forming member is formed as a gap in the magnetic path of the magnetic core 2. This air gap relaxes the magnetic saturation of the magnetic core 2 so that the function of the current transformer is not lost. As shown in FIG. 4, the gap L is substantially the end face of the case 6 when the magnetic cores 4 and 4 are connected by surface contact by the connecting member 5. The variation of the gap width L due to factors other than the thickness of the end face portion 6a of the case 6 is defined by the thickness of the portion 6a. Therefore, when setting the gap width L, the gap width L can be more accurately realized by setting the thickness of the end surface portion 6a of the case 6 to be half the width L. Moreover, since the magnetic pieces 4 and 4 are connected by surface contact, the width L of the gap can be maintained with higher accuracy.

  Further, in the current transformer 1 of the present embodiment, one of the connecting members 5 and 5 adjacent to each other by the connection has an engaging piece 8 that protrudes toward the other connecting member 5. The other connecting member 5 has an engaging recess 9 that engages with the engaging piece 8. Since the bent part of the protruding tip of the engagement piece 8 is hooked on the recess of the engagement recess 9 and the engagement piece 8 is locked to the engagement recess 9, a stronger connection state is realized.

  FIG. 6 is a perspective view of a core unit in a current transformer which is another embodiment of the present invention. In FIG. 6, the same reference numerals are given to portions common to the embodiment shown in FIGS. 1 to 5, and description thereof is omitted.

  In the embodiment shown in FIG. 6, the shape and arrangement of the engagement pieces and the engagement recesses included in the connecting member 5 are different from those of the above-described embodiment. In the present embodiment, one end surface portion 6a of the case 6 is integrally provided with engagement pieces 18 protruding in a columnar shape at four locations on the end surface, and the other end surface portion 6a of the case 6 has The engaging recess 19 is provided at four locations on the end face. The engaging piece 18 has a cylindrical outer shape, and the engaging recess 19 has a hole having a shape that matches the outer shape of the engaging piece 18.

  Also in the case 6 in the other core unit connected to the core unit shown in FIG. 6, the engagement recess is located at a position corresponding to the engagement piece 18 provided on one end surface portion 6a of the case 6 shown in FIG. 19 is provided, and an engagement piece 18 is provided at a position corresponding to the engagement recess 19 provided in the other end surface portion 6a of the case 6 shown in FIG.

  In this embodiment, since the engagement piece 18 is inserted into the engagement recess 19 and the engagement piece 18 is engaged with the engagement recess 19, a stronger connection state is realized.

  As mentioned above, although embodiment of this invention was described, it is not limited to this embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above-described embodiment, two semicircular magnetic pieces are connected by a connecting member to form an annular magnetic core. However, the shape of the magnetic core is not limited to an annular shape. It may be a polygonal ring. Accordingly, the shape of the magnetic piece can be changed to a shape other than the semicircular shape so that the magnetic core is formed in a polygonal ring shape. The number of magnetic pieces is not limited to two and may be three or more. When the connecting member is configured as a gap forming member, the number of connecting members increases as the number of magnetic pieces increases, and as a result, the number of gaps in the magnetic path also increases. Even if the number increases, a current transformer having equivalent performance can be obtained by designing the gap forming member so that the sum of the gap widths matches by adjusting the thickness of the gap forming member.

  In the above embodiment, the secondary winding is wound around the magnetic piece by using a winding machine. However, a secondary winding of an air core winding that has been wound in advance is prepared, and the secondary winding of the air core winding is prepared. By inserting a magnetic piece inside the winding, it is possible to produce a magnetic piece around which the secondary winding is wound. The shapes and arrangements of the engagement pieces and the engagement recesses included in the connecting member are not limited to the above-described embodiment, and various design changes can be made.

DESCRIPTION OF SYMBOLS 1 Current transformer 2 Magnetic body core 3 Secondary winding 4 Magnetic body piece 5 Connection member 8,18 Engagement piece 9,19 Engagement recessed part 6 Case 6a End surface part

Claims (3)

In a current transformer in which a secondary winding is wound around a magnetic core,
The magnetic core includes a plurality of magnetic body pieces and a connecting member provided on an end surface of each magnetic body piece, and is formed in an annular shape by connecting the connecting members to each other. .   The case includes a case for holding the magnetic piece formed so as to cover an end face of the magnetic piece, and a portion of the case facing the end face of the magnetic piece forms the connecting member. The current transformer according to 1.   Of the connecting members adjacent to each other, one of the connecting members has an engaging piece that protrudes toward the other connecting member, and the other connecting member has an engaging recess that engages with the engaging piece. The current transformer of Claim 1 or 2 characterized by these.

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