JP5115537B2 - Trance - Google Patents

Description

  The present invention relates to a transformer, and more particularly to a transformer in which the number of turns of a primary winding and the number of turns of a secondary winding are different.

  As a transformer, one having a configuration including a drum type core having a pair of flange portions and a winding core portion connecting the pair of flange portions is known. A primary winding and a secondary winding made of an insulation-coated copper wire are wound around the core of the drum type core. One end or the other end of the winding is electrically connected to a terminal electrode provided on the flange. The number of turns of the primary winding wound around the winding core is the same as the number of turns of the secondary winding. Such a transformer is described in, for example, Japanese Patent Laid-Open No. 10-326715 (Patent Document 1).

Japanese Patent Laid-Open No. 10-326715

  Depending on the transformer, unlike the above-described transformer, the number of turns of the primary winding wound around the winding core and the number of turns of the secondary winding are different, that is, the primary winding and the secondary winding. In some cases, the primary winding and the secondary winding are wound around the core so that the winding ratio is different. In such a case, for example, one winding having a large number of turns is wound around the entire surface of the core portion along the axial direction of the core portion, and the winding in which the one winding is wound. A winding method in which the other winding is wound from above the core is conceivable.

  In this case, the one winding may remain on the peripheral surface of the core portion without being wound in one layer, but such a surplus portion is set as the second layer, and the surplus portion is 2 It is conceivable that the other winding is similarly wound as a second layer in a small space on the one winding of the first layer that is not stacked as a layer.

  In this case, since the surplus portion is extensively stacked on the first layer as the second layer, the space for winding the other winding as the second layer is reduced, and the other winding is placed in a narrow space. Winding is difficult because the wire must be wound. Further, the magnetic coupling between one winding and the other winding is deteriorated.

  Therefore, an object of the present invention is to provide a transformer in which windings are easy to wind and magnetic coupling between a primary winding and a secondary winding is good.

  In order to achieve the above object, the present invention provides a drum-type core having a core part and flanges provided at both ends in the axial direction of the core part, respectively, and wound around the core part. The number of primary windings and secondary windings provided is the same as the number of one end portions of the primary winding and the secondary winding in one of the flange portions, and the primary winding is provided in the other flange portion. A terminal electrode provided with the same number as the other ends of the wire and the secondary winding, and the primary winding, one end of the secondary winding, and the other end of the secondary winding electrically connected to each other; The number of turns of the primary winding and the number of turns of the secondary winding are different, and the number of turns of the primary winding and the number of turns of the secondary winding is larger. The winding is wound on the peripheral surface of the core portion along the axial direction of the core portion from the one flange portion to the other flange portion, or the one flange portion and the one flange portion Between the other collar and the core It is not included in the layered circumferential surface immediately above winding part that is wound on the circumferential surface of the core part so as to reciprocate along the direction and forms an odd number of layers, and the layered circumferential surface directly above winding part In the axial direction of the core portion on the winding portion immediately above the laminar circumferential surface between a predetermined position consisting of a surplus portion and from the other collar portion toward the one collar portion and the other collar portion A surplus part layered winding part which is wound so as to reciprocate along and forms an even layer, and the number of turns of the primary winding and the secondary winding is small. The other of the windings is a superimposed winding wound in the axial direction of the winding core portion on the winding portion immediately above the laminar circumferential surface where the surplus portion layered winding portion is not provided. A transformer having a part is provided.

  Unlike the number of turns of the primary winding and the number of turns of the secondary winding, one of the windings of the number of turns of the primary winding and the number of turns of the secondary winding is It is wound on the peripheral surface of the core part along the axial direction of the core part toward the other collar part, or between the one collar part and the other collar part in the axial direction of the core part A layered portion directly above the circumferential surface of the odd-numbered layer wound on the circumferential surface of the winding core portion so as to reciprocate along, and a surplus portion not included in the wound portion immediately above the layered circumferential surface It is wound so as to reciprocate along the axial direction of the core portion on a layered circumferentially wound portion between a predetermined position from the other flange portion toward one flange portion and the other flange portion. An extra layer layered winding part having an even number of layers, and the other winding having a smaller number of turns of the primary winding and the secondary winding has a remainder layered winding. Layered circumferential surface with no part Since it has a superimposed winding part that is wound along the axial direction of the core part over substantially the entire part on the winding part, an area for arranging the superimposed winding part in the axial direction of the core part is provided. Widely secured. For this reason, the winding operation | work of the other coil | winding can be made easy. In addition, by arranging the overlapping winding part widely in the axial direction of the core part in the area for arranging the widely secured overlapping winding part, the magnetic coupling between one winding and the other winding is achieved. Can be improved.

  Here, the overlapping winding portion extends along the axial direction of the core portion over substantially the entire portion on the winding portion immediately above the laminar circumferential surface where the surplus portion layered winding portion is not provided. It is preferable to be provided. "Over almost the entire portion on the winding portion directly above the layered circumferential surface where the surplus portion layered winding portion is not provided" means that the layered circumferential surface is not provided with the surplus portion layered winding portion. This includes not only the case of covering the entire upper winding portion but also the case where the overlapping winding portion is provided in a region slightly narrower than the entire portion.

  Since the overlapping winding part is provided along the axial direction of the core part over substantially the entire part on the winding part immediately above the layered circumferential surface where the surplus part layered winding part is not provided, The magnetic coupling between the other winding and the other winding can be improved reliably.

  Further, in the axial direction of the winding core portion, the end portion on the one flange portion side of the overlapping winding portion is the end portion on the one flange portion side of the uppermost layer of the layered circumferential surface winding portion. It is preferable that, in the axial direction of the winding core portion, the end portion on the other flange side of the overlapping winding portion is in contact with the surplus portion layered winding portion.

  In the axial direction of the winding core, one end of the overlapping winding portion on the side of the flange contacts the end of one of the uppermost layers of the winding portion directly above the circumferential surface, and the other end of the overlapping winding portion Since the end on the flange side is in contact with the surplus part layered winding part, one end in the axial direction of the winding core part in the region on the winding part directly above the circumferential surface where the overlapping winding part can be arranged It can be set as the state by which the overlapping winding part was arrange | positioned from the other end to the other end. For this reason, it is possible to secure a wider area where the winding portion directly above the circumferential surface and the overlapping winding portion overlap, and to further improve the magnetic coupling between one winding and the other winding.

  Further, in the axial direction of the winding core portion, it is preferable that the end portion on the other flange side of the overlapping winding portion and the surplus portion layered winding portion are separated from each other.

  Since the end portion on the other flange side of the overlapping winding portion and the surplus portion layered winding portion are separated from each other, when the other winding is wound, the other winding is the surplus portion layered winding portion. Can be more effectively prevented, and it is possible to prevent the peripheral surface of one of the windings constituting the surplus layered winding portion from being damaged by the contact.

  Further, in the overlapping winding part, it is preferable that the peripheral surfaces of the other winding are separated from each other with a predetermined interval in the axial direction of the winding core part.

  In the overlapping winding portion, the circumferential surfaces of the other windings are separated from each other at a predetermined interval in the axial direction of the winding core portion, so that a wide overlapping winding portion is secured in the axial direction of the winding core portion. be able to. For this reason, it is possible to secure a wider area in the axial direction of the core portion where the winding portion directly overlaps with the winding portion in the direction perpendicular to the axial direction of the core portion. And the other winding can be further improved in magnetic coupling.

  As described above, the present invention can provide a transformer in which winding is easy and magnetic coupling between the primary winding and the secondary winding is good.

The top view which shows the transformer by embodiment of this invention. The top view which shows the state from which the plate-shaped core was removed from the trans | transformer by embodiment of this invention. The front view which shows the trans | transformer by embodiment of this invention. The side view which shows the trans | transformer by embodiment of this invention. Sectional drawing along II-II of Fig.1 (a). The schematic sectional drawing which shows the winding state of the primary winding of the modification of the transformer by embodiment of this invention, and a secondary winding. The schematic sectional drawing which shows the winding state of the primary winding of the other modification of the transformer by embodiment of this invention, and a secondary winding.

  A transformer according to an embodiment of the present invention will be described with reference to FIGS. The transformer 100 includes a ferrite drum type core 1 as shown in FIG. 1, a primary winding 21, a secondary winding 22 wound around the drum type core 1, and a ferrite plate-like core 3. It is a so-called balun transformer.

  As shown in FIG. 1, the drum type core 1 includes a pair of flange portions 11 and 12 and a core portion 13 (FIG. 2). The flange portions 11 and 12 are arranged in the axial direction of the core portion 13. Provided at both ends, the core portion 13 connects the pair of flange portions 11 and 12 to each other.

  The pair of flanges 11 and 12 have substantially the same substantially rectangular parallelepiped shape, and one of the widest pair of surfaces 11A among the six surfaces of the one flange 11 that defines the substantially rectangular parallelepiped shape. The substantially center position is connected to one end of the core part 13. Similarly, the substantially center position of the other 12A of the widest pair of surfaces among the six surfaces defining the substantially rectangular parallelepiped shape of the other flange portion 12 is connected to the other end of the core portion 13. Yes.

  The surfaces 11A and 12A that define the pair of flanges 11 and 12 that are connected to one end and the other end of the winding core portion 13 are symmetrical relative to each other, and are substantially rectangular surfaces. The four corners 11 </ b> A and 12 </ b> A are in a positional relationship facing each other in the axial direction of the core 13. Further, the surfaces 11A and 12A have a substantially parallel positional relationship.

  The pair of flange portions 11 and 12 are provided with terminal electrodes 14 and 15 and terminal electrodes 16 and 17, respectively. A total of four terminal electrodes 14 to 17 are provided in each of the pair of flanges 11 and 12, a number corresponding to the total number of primary windings 21 and secondary windings 22. Each of the terminal electrodes 14 to 17 has a band shape, and has one end portions 14A, 15A, 16A and 17A, the other end portions 14B, 15B, 16B and 17B, and central portions 14C, 15C, 16C and 17C.

  The one end portions 14A and 15A are disposed on the upper surface 11B of the flange portion 11 at a predetermined interval. The other end portions 14B and 15B are disposed on the bottom surface 11C of the flange portion 11 at a predetermined interval. The central portions 14C and 15C are disposed on the side surface 11D of the flange portion 11 with a predetermined interval.

  Similarly, the one end portions 16A and 17A are arranged on the upper surface 12B of the flange portion 12 with a predetermined interval. The other end portions 16B and 17B are disposed on the bottom surface 12C of the flange portion 12 with a predetermined interval. The central portions 16C and 17C are arranged on the side surface 12D of the flange portion 12 with a predetermined interval.

  The other end portions 14B to 17B of the terminal electrodes 14 to 17 form user electrodes that are electrically connected to a conductive pattern on a mounting board (not shown). The portion of the upper surface 11B of the flange portion 11 between the end portions 14A and 15A of the terminal electrodes 14 and 15 and the portion of the upper surface 12B of the flange portion 12 between the end portions 16A and 17A of the terminal electrodes 16 and 17 are absent. The parts 11E and 12E are formed.

  The core portion 13 has a substantially square prismatic cross section cut in the longitudinal direction, that is, a cross section cut perpendicular to the axial direction, and as described above, one end and the other end in the axial direction are The pair of flanges 11 and 12 are connected to the surfaces 11A and 12A, respectively.

  The primary winding 21 has a diameter of about 0.06 mm, and the secondary winding 22 has a diameter of about 0.03 mm. Accordingly, the primary winding 21 is twice as thick as the secondary winding 22. The primary winding 21 and the secondary winding 22 are each made of a copper wire coated with a highly insulating insulating material.

  One end portions of the primary winding 21 and the secondary winding 22 are fixedly connected to one end portions 14A and 15A of the terminal electrodes 14 and 15 of the one flange portion 11 and are electrically connected and connected. The primary winding 21 and the secondary winding 22 are respectively wound spirally around the core portion 13 of the drum type core 1 using a winding device (not shown). The other end portions of the primary winding 21 and the secondary winding 22 are fixedly connected to one end portions 16A and 17A of the terminal electrodes 16 and 17 of the other flange portion 12, respectively, and are electrically connected and connected. . The one end and the other end of the primary winding 21 and the secondary winding 22 are fixed to the terminal electrodes 14 to 17 by thermocompression using a heater chip (not shown).

  The winding of the primary winding 21 and the secondary winding 22 in the winding core 13 (FIG. 2) is as follows. The primary winding 21 is wound around the winding core 13 for 12 turns, and the secondary winding 22 is wound around the winding core 13 for 79 turns. When viewed in the cross-sectional view shown in FIG. 2, in the axial direction of the core portion 13, the peripheral surfaces of the portions of the primary winding 21 constituting each turn of the adjacent primary winding 21 are secondary windings. The peripheral surfaces of the portion of the secondary winding 22 constituting each turn of the wire 22 are wound with no gap so as to contact each other.

  More specifically, the secondary winding 22 comes into contact with the peripheral surface of the core portion 13 immediately above the peripheral surface of the core portion 13, from the portion of the core portion 13 that is connected to the one flange portion 11. It is wound 44 turns in the axial direction of the core part 13 until it reaches the part of the core part 13 connected to the other flange part 12, that is, from one end to the other end in the axial direction of the core part 13. ing. This part of the secondary winding 22 corresponds to the layered circumferential surface immediately above winding part 22-1.

  Of the remaining 35 turns of the 79 turns of the secondary winding 22, 18 turns following the winding part 22-1 immediately above the circumferential surface are wound on the winding part 22-1 immediately above the circumferential surface. That is, in the 18 turns, the winding portion 22-1 provided directly above the circumferential surface is provided in the axial direction of the core portion 13 from the other flange portion 12 to the substantially central position in the axial direction of the core portion 13. It is wound around the core part 13.

  Of the 79 turns of the secondary winding 22, 44 turns were wound as described above, and the remaining 17 turns after 18 turns were wound on the winding portion 22-1 immediately above the circumferential surface. It is further wound on the above 18 turns. More specifically, the 17 turns include the winding portion 22-1 directly above the circumferential surface in the axial direction of the core portion 13 from the substantially central position in the axial direction of the core portion 13 to the vicinity of the other flange portion 12. It is wound further on the core part 13 provided with the above-mentioned 18 turns. A portion corresponding to 35 turns of the above-described secondary winding 22 wound on the winding portion 22-1 directly above the peripheral surface corresponds to the surplus layered winding portion 22-2.

  All the 12 turns of the primary winding 21 are wound on the winding portion 22-1 directly above the circumferential surface. More specifically, the primary winding 21 is wound in the axial direction of the core portion 13 from one flange portion 11 to a substantially central position in the axial direction of the core portion 13. That is, the primary winding 21 is wound over the entire portion of the winding core portion 13 on the winding portion 22-1 immediately above the circumferential surface and not provided with the surplus layered winding portion 22-2. Yes. A portion corresponding to 12 turns of the primary winding 21 wound around the winding core portion 13 corresponds to the overlapping winding portion 21-1.

  As described above, the secondary winding 22 includes the winding part 22-1 directly above the circumferential surface and the surplus layered winding part 22-2 provided on the winding part 22-1 directly above the circumferential surface. Since the next winding 21 has a superimposed winding portion 21-1 wound around a portion on the winding portion 22-1 immediately above the circumferential surface where the surplus portion layered winding portion 22-2 is not provided. In addition, it is possible to secure a wide area for arranging the overlapping winding part 21-1 in the axial direction of the winding core part 13. For this reason, the winding operation | work of the primary winding 21 can be made easy, and the magnetic coupling of the primary winding 21 and the secondary winding 22 can be improved.

  As shown in the lower side of FIG. 2, in the axial direction of the core portion 13, the end portion on the one flange portion 11 side of the overlapping winding portion 21-1 is one of the winding portions 22-1 directly above the circumferential surface. It is in contact with the end on the flange 11 side. More specifically, a portion of the primary winding 21 that constitutes the overlapping winding portion 21-1 is a part of the secondary winding 22 and is part of the first turn counted from one flange portion 11. Therefore, the portion of the first turn counting from one flange 11 is in contact. Further, as shown in the lower side of FIG. 2, in the axial direction of the winding core portion 13, the end portion on the other flange portion 12 side of the overlapping winding portion 21-1 is formed as a surplus layered winding portion 22-2. It is in contact. More specifically, it is a part of the 18 turns of the lower layer (upper layer in the lower side of FIG. 2) of the two layers that constitute part of the secondary winding 22 and constitute the surplus layered winding part 22-2. In the first turn portion counted from one flange portion 11, the first turn is a part of the primary winding 21 constituting the overlapping winding portion 21-1 and counted from the other flange portion 12. The parts are in contact.

  Thus, in the axial direction of the winding core portion 13, the end portion on the one flange portion 11 side of the overlapping winding portion 21-1 is the end portion on the one flange portion 11 side of the winding portion 22-1 directly above the circumferential surface. And the end on the other flange 12 side of the overlapped winding portion 21-1 is in contact with the surplus portion layered winding portion 22-2. In the region of the part on the winding part 22-1 immediately above the surface, the overlapping winding part 21-1 can be arranged from the end to the end of the core part 13 in the axial direction. For this reason, in the direction orthogonal to the axial direction of the core part 13, it is possible to secure a wider area where the winding part 22-1 and the overlapping winding part 21-1 directly overlap the circumferential surface, Magnetic coupling with the other winding can be further improved.

  Since the primary winding 21 has a thickness twice that of the secondary winding 22 as described above, the overlapping winding portion 21-extends from the upper surface of the core portion 13 in the vertical direction of FIG. The height h1 to the upper end of the primary winding 21 constituting the upper end of 1 and the upper end of the secondary winding 22 constituting the upper end of the surplus layered winding part 22-2 from the upper surface of the core part 13 The height h2 is substantially the same. For this reason, the height h3 from the upper surface of the core part 13 to the upper surface of the collar parts 11 and 12 in the up-down direction of FIG. Can be achieved.

  The plate-like core 3 has a substantially plate-like substantially rectangular shape. A convex portion 3 </ b> A is provided at one end and the other end in the longitudinal direction of the plate-like core 3 and at the center position in the width direction of the plate-like core 3. The convex portion 3A faces the electrode absence portions 11E and 12E of the flange portions 11 and 12 in a state where the plate-like core 3 is fixed to the drum type core 1, and adheres to the electrode absence portions 11E and 12E. It is fixed by the agent. A circular mark 3B (FIG. 1A) indicating the direction of the plate core 3 is provided on the upper surface of the plate core 3.

  The method of manufacturing a transformer according to the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims. For example, although the surplus part layered winding part 22-2 was provided in the part of the core part 13 near the other collar part 12, it is not limited to this. For example, like the transformer 200 shown in FIG. 3, it may be provided in both the portion of the core portion 13 near the other flange portion 12 and the portion of the core portion 13 near the one flange portion 11.

  When winding the secondary winding 22, the secondary winding 22 is positioned and fixed at the center position of the core portion 13 in the axial direction of the core portion 13, and as shown by the arrows in FIG. The secondary winding 22 is spirally wound around the core portion 13 toward the portions 11 and 12 to form a winding portion 22-1 immediately above the circumferential surface. About the formation of the surplus part layered winding part 22-2, one hook part 11 and one hook part 11 in the vicinity of the one hook part 11 and the other hook part 12 as in the present embodiment. Between the position on the core part 13 separated by a predetermined distance from the other flange part 12 and the position on the core part 13 spaced apart from the other collar part 12 by a predetermined distance. What is necessary is just to form by winding the secondary winding 22 so that it may reciprocate to the axial direction of the core part 13. FIG.

  Further, in the present embodiment, in the axial direction of the core portion 13, the end portion on the one flange portion 11 side of the superimposed winding portion 21-1 is the one flange portion 11 of the winding portion 22-1 directly above the circumferential surface. In the axial direction of the core portion 13, the end portion on the other flange portion 12 side of the overlapping winding portion 21-1 is in contact with the surplus layered winding portion 22-2. However, the contact does not have to be made in this way.

  For example, in the axial direction of the winding core part 13, the end part on the other flange part 12 side of the overlapping winding part 21-1 and the surplus part layered winding part 22-2 are shorter than the diameter of the primary winding 21. They may be separated by a distance. By doing in this way, when winding the primary winding 21, it can prevent more effectively that the primary winding 21 contacts the surplus part layered winding part 22-2, and the remainder It is possible to prevent the peripheral surface of the secondary winding 22 constituting the partial layer winding part 22-2 from being damaged due to the contact.

  Further, in the present embodiment, the circumferential surfaces of the primary windings 21 constituting each turn of the primary windings 21 adjacent in the axial direction of the core part 13 are wound without gaps so as to contact each other. Although it was turned, it is not limited to this. For example, as shown in FIG. 4, in the overlapping winding part 21-1, the circumferential surfaces of the primary windings 21 in the axial direction of the core part 13, that is, the turns of the adjacent primary windings 21 are configured. The peripheral surfaces of the portion of the primary winding 21 to be wound may be wound at regular intervals with a predetermined interval therebetween.

  By doing in this way, the overlap winding part 21-1 can be ensured widely in the axial direction of the winding core part 13. For this reason, in the direction orthogonal to the axial direction of the core part 13, a region where the winding part 22-1 directly above the circumferential surface overlaps with the overlapping winding part 21-1 is secured wider in the axial direction of the core part 13. In addition, the magnetic coupling between the secondary winding 22 and the primary winding 21 can be further improved.

  Further, the number of turns and the diameter of the primary winding 21 and the secondary winding 22 are not limited to the numerical values of the present embodiment. For example, when the number of turns of the secondary winding 22 is large, the winding part 22-1 directly above the circumferential surface is between the one flange part 11 and the other flange part 12 in the axial direction of the core part 13. What is necessary is just to make it form the layer shape of an odd number layer by winding on the surrounding surface of the core part 13 so that it may reciprocate along. Here, in the case where the number of turns of the secondary winding 22 is large but the winding part 22-1 immediately above the circumferential surface becomes an even layer, the remaining number is an odd layer that is one less than the even number, and the rest What is necessary is just to make the part of the secondary winding 22 into the surplus part layered winding part 22-2.

  Further, for example, the secondary winding 22 is wound for a total of 72 turns, and is applied as a layered circumferential surface directly above the circumferential surface of the core portion 13 to the circumferential surface of the core portion 13. The secondary winding 22 is wound 41 turns in contact, and the remaining 31 turns of the 72 turns of the secondary winding 22 have 16 turns following the winding portion 22-1 immediately above the circumferential surface. The remaining 15 turns after being wound on the part 22-1 and wound for 41 turns and further 16 turns among the 72 turns of the secondary winding 22 are wound immediately above the circumferential surface. It may be wound further on the above-mentioned 16 turns wound on the part 22-1.

  Moreover, the shape of a collar part or a core part is not limited to the shape of this Embodiment.

  The present invention is particularly useful in the field of transformers that require good magnetic coupling between the primary winding and the secondary winding.

DESCRIPTION OF SYMBOLS 1 Drum type cores 11 and 12 鍔 part 13 Core parts 14, 15, 16, and 17 Terminal electrode 21 Primary winding 21-1 Superimposed winding part 22 Secondary winding 22-1 Winding part 22- immediately above the circumferential surface 2 Remainder layered winding part 100, 200 transformer

Claims (5)

A drum type core having a core part, and flanges respectively provided at both ends in the axial direction of the core part;
A primary winding and a secondary winding respectively wound around the winding core;
The number of one end portions of the primary winding and the secondary winding is provided in one of the flange portions, and the number of the other end portions of the primary winding and the secondary winding is provided in the other flange portion. A terminal electrode electrically connected to each of the primary winding, one end of the secondary winding, and the other end, respectively,
Unlike the number of turns of the primary winding and the number of turns of the secondary winding,
One of the windings of the number of turns of the primary winding and the secondary winding has a large number of turns, the axial direction of the core part from the one flange part toward the other flange part The winding core is wound on the peripheral surface of the winding core section along the axis or reciprocated along the axial direction of the winding core section between the one collar section and the other collar section. A layered circumferentially wound portion that is wound on the circumferential surface of the portion to form an odd-numbered layer, and a surplus portion that is not included in the wound portion directly above the circumferential surface of the layer. Evenly wound around the layered circumferentially wound portion between the predetermined position toward one collar and the other collar so as to reciprocate along the axial direction of the core. A surplus part layered winding part that forms a layer of the layer,
The other winding with the smaller number of turns of the primary winding and the secondary winding is the winding portion immediately above the layered peripheral surface where the excess layered winding portion is not provided. A transformer having an overlapping winding portion wound in an upper portion along an axial direction of the winding core portion.   The overlapping winding part is provided along the axial direction of the core part over substantially the entire part on the winding part immediately above the laminar circumferential surface where the surplus part layered winding part is not provided. The transformer according to claim 1, wherein:   In the axial direction of the winding core portion, the end portion on the one flange portion side of the overlapping winding portion is in contact with the end portion on the one flange portion side of the uppermost layer of the layered circumferential surface. 3. The transformer according to claim 2, wherein an end portion of the overlapping winding portion on the other flange side is in contact with the surplus layered winding portion in the axial direction of the winding core portion.   2. The transformer according to claim 1, wherein in the axial direction of the winding core portion, the end portion on the other flange portion side of the overlapping winding portion and the surplus portion layered winding portion are separated from each other.   5. The superimposed winding portion according to any one of claims 1 to 4, wherein the circumferential surfaces of the other winding are separated from each other at a predetermined interval in the axial direction of the winding core portion. A transformer according to any one of the above.

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