JP2004119682A - Coil for mold transformer and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a coil for mold transformer having a structure where a plurality of unit coils are arranged and are connected in series. <P>SOLUTION: Two unit coils 10A and 10B different in winding directions are adjacently disposed, and inner peripheral side terminals 12A and 12B of the unit coils are connected on inner peripheral sides of the coils. Thus, group coils C1, C2 and the like are constituted. Consequently, the coil for mold transformer is constituted by arranging a plurality of the group coils C1 and C2 and mutually connecting terminals on outer peripheral sides of the adjacent unit coils. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coil for a molded transformer suitable for use as a high-voltage side coil of a molded transformer, and a method for manufacturing the coil.
[0002]
[Prior art]
The molded transformer has a structure in which a coil is molded with an insulating resin such as an epoxy resin. 2. Description of the Related Art As a high-voltage side coil used in a mold transformer, a coil having a structure in which a plurality of unit coils arranged side by side in a winding axis direction are sequentially connected in series is known (for example, see Patent Document 1).
[0003]
In this type of conventional coil, as shown in FIG. 13, a large number of coils formed by winding a thin conductor (sheet conductor) 1 such as a strip conductor or a foil conductor via an interlayer insulating paper 2. The unit coils 3a, 3b, ..., 3f are arranged side by side in the direction of the winding axis OO, and these unit coils are sequentially connected in series to form one coil 4. The coil 4 is embedded in the mold resin layer 5 to form a coil 6 for a molded transformer.
[0004]
In this type of conventional coil, the winding direction of each of a series of unit coils 3a, 3b,... Is the same, and the terminal end 301 on the outer peripheral side of each unit coil and the adjacent unit coil A series of unit coils were connected in series by connecting the winding-side terminal portion 302 on the circumferential side with the adjacent unit coils crossing over.
[0005]
As described above, when a unit coil is wound in a so-called sheet winding structure using a thin-plate conductor, the space factor of the conductor increases, so that the cross-sectional area of the coil can be reduced.
[0006]
[Patent Document 1]
JP-A-11-45811
[Problems to be solved by the invention]
In a conventional molded transformer coil having a structure in which a plurality of unit coils are arranged in series and connected in series, the winding direction of all the unit coils is the same, so that a transition between adjacent unit coils in the radial direction of the coil is performed. The connecting portion has to be arranged between adjacent unit coils.
[0008]
In a coil having such a structure, it is necessary to secure an insulation distance between adjacent unit coils to prevent dielectric breakdown of the mold resin, so that the axial dimension (height dimension) of the coil is reduced. I couldn't avoid getting bigger.
[0009]
Therefore, in spite of using a unit coil having a winding structure with a large space factor of the conductor, the characteristics of the conventional molded transformer coil cannot be fully utilized, and the coil becomes large. There was a problem.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to provide a coil for a molded transformer in which the interval between adjacent unit coils can be made smaller than before so as to reduce the size of the coil, and a method of manufacturing the coil.
[0011]
[Means for Solving the Problems]
The present invention provides a unit coil group in which a plurality of unit coils are arranged side by side in a winding axis direction, and a series of unit coils constituting the unit coil group are sequentially connected in series by a cross connection unit to form one coil. Is applied to a coil for a molded transformer.
[0012]
In the coil according to the present invention, each unit coil has a structure in which a predetermined number of turns are continuously wound in a state where a strip-shaped thin plate conductor is insulated between layers, and a series of unit coils constituting a unit coil group are formed. Are arranged in such a manner that winding directions of adjacent unit coils are alternately changed. In addition, a series of unit coils connects a transition connection portion that connects a winding end and a winding start of an adjacent unit coil on the inner peripheral side of the coil and a winding end and a winding start of an adjacent unit coil on the outer peripheral side of the coil. The connecting portions are connected in series by a connecting structure in which the connecting portions are alternately arranged in the winding axis direction.
[0013]
With the configuration described above, the connection between adjacent unit coils can be performed on the inner peripheral side and the outer peripheral side of the coil, and there is no need to arrange a cross connection portion extending in the radial direction of the coil between the adjacent coils. Therefore, the distance between adjacent unit coils can be made narrower than in the related art, so that the axial dimension of the coil can be reduced.
[0014]
Therefore, it is possible to reduce the size of the coil by taking advantage of the characteristic of the coil winding structure made of the thin plate-shaped conductor that the space factor of the conductor is large.
[0015]
In a preferred embodiment of the present invention, the two unit coils are arranged side by side in the winding axis direction with their respective winding directions being different, and the terminal portions on the inner peripheral side of both unit coils are mutually connected by the connecting portion. A plurality of connected coils having a connected structure are arranged side by side in the direction of the winding axis to form a unit coil group, and a terminal portion on an outer peripheral side of an adjacent unit coil of an adjacent set coil of the unit coil group is connected. A series of unit coils are connected in series and connected in series. Also in this case, each unit coil has a structure in which a strip-shaped thin plate conductor is continuously wound for a predetermined number of turns in a state where insulation is applied between layers.
[0016]
The above-mentioned thin-plate conductor may be a strip-shaped conductor whose thickness is sufficiently smaller than its width so as to prevent collapse when a coil is formed by multilayer winding. As the thin plate-shaped conductor, a strip-shaped conductor having the same thickness as a strip conductor or a foil conductor conventionally used in a transformer, or a strip-shaped conductor slightly thicker than these conductors can be used. .
[0017]
In a preferred aspect of the present invention, an insulating tape is wrapped around the thin plate conductor constituting each unit coil, and the thin plate conductor is covered with the insulating tape, and insulation between the layers of each unit coil is provided by the insulating tape. You.
[0018]
Further, in another preferred aspect of the present invention, the insulating paper is arranged in a state of being attached to one surface of the thin conductor constituting the unit coil, and the insulating tape is roughly formed on the polymer of the insulating paper and the thin conductor. It is wound, and the insulation between the layers of each unit coil is given by the insulating paper.
[0019]
If the insulation between the coil layers is provided by the insulating tape fixed to the thin conductor as described above or the insulating paper fixed to the thin conductor by the insulating tape, the insulating paper is inserted between the layers when the unit coil is wound. Since it is possible to save time and effort, the coil can be easily wound.
[0020]
However, the present invention is not limited to the case where the insulation between the layers of the unit coil is performed with the above-described structure, and the insulation between the coil layers may be performed by the interlayer insulating paper wound together with the thin plate-shaped conductor. Good.
[0021]
In a preferred aspect of the present invention, at each connecting portion, one terminal of adjacent unit coils connected to each other by each connecting portion is bent toward the terminal portion of the other unit coil, and bent. The terminal portion of one unit coil is overlapped and connected to the terminal portion of the other unit coil.
[0022]
In another preferred aspect of the present invention, at each of the connecting portions, one terminal portion of the adjacent unit coils connected to each other by each of the connecting portions is bent once so as to face the terminal portion side of the other unit coil. After that, the bent end of the one unit coil is further bent along the longitudinal direction of the terminal portion of the other unit coil, and the end of the one unit coil becomes the end of the other unit coil. It is superimposed on the terminal and connected.
[0023]
When the connecting portion is configured as described above, the connecting portion can be formed thin, and the ratio of the connecting portion in the radial direction of the coil can be reduced, so that the coil can be made more compact. be able to.
[0024]
The present invention is also applied to a method of manufacturing a coil for a molded transformer in which a number of unit coils arranged side by side in the winding axis direction are sequentially connected in series to form one coil.
[0025]
In the manufacturing method of the present invention, a unit coil winding step of winding a unit coil by continuously winding a predetermined number of turns in a state where a strip-shaped thin plate conductor is insulated between layers; Are arranged side by side in a state where the winding directions are different from each other and the respective winding axes are substantially aligned with each other. A coil assembly manufacturing process for manufacturing a group coil by connecting the terminal portion to the terminal portion on the inner peripheral side of the other unit coil, and a plurality of group coils manufactured in the group coil manufacturing process arranged side by side and arranged adjacent to each other And a step of connecting the ends of the assembled coil to each other on the outer peripheral side of the coil.
[0026]
In the above method, in order to make the winding directions of adjacent unit coils different from each other, the winding direction when winding a series of unit coils is the same, and when arranging the unit coils, The axial directions of the coils may be different from each other by 180 °.
[0027]
As described above, a unitary coil is manufactured by connecting two unit coils having different winding directions to each other and connecting the terminal portions on the inner peripheral side of both unit coils to each other, and forming a plurality of the unitary coils. By arranging the coils side by side, the terminals on the inner peripheral side of the unit coils constituting each set coil can be connected within the window of one of the unit coils, so that the interval between the unit coils is reduced. Thus, the axial dimension of the coil can be reduced.
[0028]
When the coil is manufactured by the above-described method, the formation of the inner connecting portion may be performed for the two unit coils constituting the assembled coil. When the inner connecting portion is formed, two connecting coils may be formed. Since it suffices to handle the unit coil, the operation of forming the connecting portion on the inner peripheral side can be easily performed. In addition, the operation of forming the connecting portion on the outer peripheral side can be easily performed from the outside of the coil in a state where a plurality of coil groups are arranged. Therefore, according to the present invention, it is possible to manufacture a coil as compared with a method in which a series of unit coils are connected in series while alternately forming transition connection portions on the inner peripheral side and the outer peripheral side of adjacent unit coils. Therefore, the manufacturing cost of the coil can be reduced.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A and 1B schematically show a winding structure of unit coils 10A and 10B used in the present invention. The unit coil of the present embodiment continuously winds the band-shaped thin plate-shaped conductor 11 on which the insulating coating is applied around a winding axis OO by a predetermined number of turns, and the inner peripheral side terminal portions 12A and It has a structure in which 12B and terminal portions 13A and 13B on the outer peripheral side are drawn out in the winding axis direction. The winding directions of the unit coils 10A and 10B are different, and the leading directions of the terminal portions on the inner peripheral side and the outer peripheral side are different by 180 °. As shown in FIG. 1 (C), the inner peripheral side terminal portion 12A of the unit coil 10A is pulled out by bending the terminal portion of the thin plate-shaped conductor 11 at 45 ° with respect to the longitudinal direction of the conductor 11. Can be performed by bending along. The other terminal units can be pulled out in the same manner.
[0030]
In the present invention, the unit coils 10A and 10B wound as described above are arranged side by side with the respective winding directions being different and the winding axes OO being aligned. The terminal portions 12A and 12B on the inner circumference side are connected to each other to form a group coil.
[0031]
As shown in FIG. 2, the assembled coils C1, C2,... Configured as described above are arranged side by side with their respective winding axes aligned so that a unit coil group 15 is formed. By connecting the outer peripheral terminals of the unit coils adjacent to the coil to each other by the connection unit, a series of unit coils are connected in series to form one coil 16.
[0032]
To make the winding direction of adjacent unit coils different, the winding direction when winding each unit coil is the same, and when arranging a series of unit coils side by side, the winding axis direction of the adjacent unit coils May be different from each other by 180 °.
[0033]
In the example shown in FIG. 2, the terminal portion 13A on the outer peripheral side of the unit coil 10A is the terminal portion on the winding start side (the winding start side terminal portion in the electrical sense, the same applies hereinafter), and the inner peripheral side. Is a terminal portion on the winding end side (the terminal portion on the winding end side in the electrical sense, the same applies hereinafter). Further, in the unit coil 10B, the terminal portion 12B on the inner periphery is a terminal portion on the winding start side, and the terminal portion 13B on the outer periphery is a terminal portion on the winding end side.
[0034]
A series of unit coils arranged so that the winding axes are aligned with each other is a cross-connecting part connecting the winding end and the beginning of winding of the adjacent unit coil on the inner peripheral side of the coil and the unit coil adjacent on the outer peripheral side of the coil. A transition connection portion that connects the end of the winding and the start of the winding is connected in series by a transition connection structure that is alternately arranged in the winding axis direction.
[0035]
The coil 16 configured as described above is disposed in a molding die and molded with an insulating resin, whereby a coil 18 for a molded transformer having a structure in which the coil 16 is embedded in the mold layer 17 is configured. Is done. The coil wound in such a manner is usually used as a high-voltage side coil of a transformer.
[0036]
With the above configuration, connection between adjacent unit coils can be performed on the inner and outer peripheral sides of the coil, and there is no need to arrange a connection portion between adjacent coils. Can be made smaller than in the prior art to reduce the axial dimension of the coil.
[0037]
In FIG. 2, the terminal portions of the adjacent unit coils are illustrated to be formed in the space between the adjacent unit coils. However, as described later, the connection between the adjacent unit coils is performed by two adjacent unit coils. It is preferable that the operation be performed in one window of the unit coil.
[0038]
The connection method between the terminal portions of the unit coil is arbitrary, and may be performed by welding, soldering, crimping, cold pressing, or the like.
[0039]
In the present embodiment, the thin-plate conductor 11 itself used for forming the unit coil is provided with insulation for preventing a short circuit between coil layers. The insulation of the thin-plate conductor 11 can be performed, for example, as shown in FIG. 3 or FIG. 4 and FIG.
[0040]
In the example shown in FIG. 3, the insulating tape 23 is wound around a thin plate-like conductor 11, such as a strip conductor or a foil conductor, whose thickness is sufficiently small compared to the width dimension, with the insulating tape 23 partially wrapped. The tape-shaped conductor 11 is completely covered with the tape 23.
[0041]
In the example shown in FIGS. 4 and 5, the tape-shaped interlayer insulating paper 30 is arranged in a state of being attached to one surface of the strip-shaped thin conductor 11, and the polymer 31 of the thin-plate conductor 11 and the interlayer insulating paper 30 is provided. An insulating tape 23 is roughly wound around the insulating tape 23, and the interlayer insulating paper 30 is fixed to the conductor 11 by the insulating tape 23.
[0042]
3 and 4, reference numeral 24 denotes an adhesive tape for fixing the end of the insulating tape 23 to the thin plate conductor.
[0043]
If the insulation between the layers of the coil is provided by the insulating tape or the insulating paper fixed to the thin plate-shaped conductor as described above, the work of inserting the insulating paper between the layers when the unit coils 10A and 10B are wound can be omitted. The coil can be easily wound.
[0044]
However, the present invention is not limited to the case where insulation is performed between layers of the unit coil with the above structure, and when the thin plate-shaped conductor 11 is wound in a coil shape, an interlayer insulating paper is placed between the coil layers. The coil may be wound and the insulation between the coil layers may be provided by the interlayer insulation paper.
[0045]
Next, a method for manufacturing a coil according to the present invention will be described.
[0046]
In the manufacturing method of the present invention, first, a unit coil winding step of manufacturing the unit coil by winding the thin plate conductor 11 insulated as described above around a winding axis by a predetermined number of turns is performed.
[0047]
FIG. 6 shows two unit coils 10A and 10B wound in this manner. These unit coils have the same winding direction. The terminal parts on the inner peripheral side of the unit coils 10A and 10B are 12A and 12B, respectively, and the terminal parts on the outer peripheral side of the unit coils 10A and 10B are 13A and 13B, respectively.
[0048]
Next, as shown in FIG. 7, the unit coil 10B is inverted by 180 °, the direction of the winding axis direction is made 180 ° different from that of the unit coil 10A, and the winding direction of the unit coils 10A and 10B is made different.
[0049]
Also, as shown in FIG. 10A, the end of the conductor 11 on the inner peripheral side of one of the unit coils 10A is placed on the upper side along the bending line a at 45 ° to the longitudinal direction of the conductor (unit coil 10A). The terminal portion 12A is pulled out from the unit coil 10A in the direction of the winding axis (perpendicular to the circumferential direction of the unit coil) by bending the terminal portion 12A, and the terminal portion 12A is further 45 ° with respect to the longitudinal direction of the conductor. Then, the outermost end 12A1 extending in the circumferential direction of the unit coil 10A is formed by bending the unit coil 10A to the opposite side (to the outer diameter side of the unit coil) along the bending line b.
[0050]
Similarly, the outer peripheral end of the unit coil 10A is bent, and the outer peripheral end 13A is led out to the opposite side to the inner peripheral end 12A along the winding axis direction.
[0051]
After processing the end portion of one of the unit coils 10A in this way, as shown in FIG. 8, the unit coils 10A and 10B are arranged next to each other with their winding directions being different from each other. The end 12A1 of the terminal portion 12A of the coil 10A is superimposed on the inner peripheral side terminal portion 12B of the unit coil 10B within the window of the unit coil 10B. In this state, by connecting the outermost end portion 12A1 of the inner peripheral side terminal portion 12A of the unit coil 10A to the inner peripheral side terminal portion 12B of the unit coil 10B by welding, a cross connection portion is formed, and two winding directions different from each other are formed. A group coil C composed of unit coils is formed.
[0052]
The assembled coils C1, C2,... Manufactured in this manner are fitted to the core of the mold, and a series of assembled coils are arranged in the winding axis direction as shown in FIG. A spacer is inserted between the circumference and the core to form a gap filled with the resin. Next, by connecting the outer peripheral side terminals 13A and 13B of the adjacent unit coils of the adjacent set coil to each other, a connecting portion is formed, and a series of unit coils are connected in series to form one coil.
[0053]
9 shows a state in which the assembled coils C1, C2, C3,... Are mounted on the core of the mold and are arranged in the winding axis direction, but illustration of the core of the mold is omitted. .
[0054]
After forming a coil in which a series of unit coils are connected in series as described above, the coil is inserted together with a core into a molding die, and an insulating resin is injected into the die to obtain a coil shown in FIG. Is formed.
[0055]
In the above example, as shown in FIG. 10 (A), the terminal portion of the unit coil 10A is turned back twice so that the end portion of the terminal portion of the unit coil 10A extends in the circumferential direction of the adjacent unit coil 10B. However, as shown in FIG. 10 (B), the end portion of the unit coil is bent only once and pulled out in the direction of the winding axis to form the terminal portion 12A. The distal end may be connected to the terminal portion 12B of the adjacent unit coil 10B in an overlapping manner.
[0056]
In the above description, the bending process is performed on the inner terminal portion and the outer peripheral terminal portion of the unit coil 10A, and the bending process is not performed on the terminal portions of the other unit coils 10B. For only one of the unit coils 10A and 10B, only the inner peripheral end portion is bent, and only the inner peripheral end portion is pulled out in the winding axis direction, and the outer peripheral end portion is wound around the winding axis. The bending process for drawing in the direction may be performed on the other unit coil side.
[0057]
In the above description, the terminals of the adjacent unit coils are overlapped and welded, but the terminals of the adjacent unit coils may be connected to each other by soldering.
[0058]
In the above example, in order to form a cross-connecting portion that connects the terminal portions of adjacent unit coils, the terminal portion is bent and pulled out in the coil winding axis direction, but the thin plate conductor may be bent. If it is difficult, as shown in FIG. 11, a strip-shaped conductor 35 is arranged across the adjacent unit coils 10A and 10B, and this conductor 35 is connected to the terminals 12A and 12B of the unit coils 10A and 10B. The connecting portion may be formed by welding to the end. In this case, as shown in FIGS. 11A and 11C, the connection conductor 35 has a trapezoidal cross section so as to form a groove between the ends of the terminal portions 12A and 12B. Preferably, it is used. In FIGS. 11A to 11C, W indicates a weld bead.
[0059]
As in the example shown in FIG. 11, if the connection conductor 35 is butted and welded to the ends of the terminal portions 12A and 12B via a groove, it is possible to prevent the coil from expanding. However, the present invention is not limited to the case where the connection conductors are connected in this manner. As shown in FIG. 12, the connection conductor 36 is overlapped on the terminal portions 12A and 12B of the adjacent unit coils 10A and 10B. Thus, the end in the width direction of the connection conductor 36 may be welded to the terminal of the coil.
[0060]
In the above embodiment, each unit coil is wound so as to have a substantially rectangular shape, but each unit coil may be wound so as to have a ring shape.
[0061]
【The invention's effect】
As described above, according to the present invention, the winding directions of the adjacent unit coils are made different and the connection between the adjacent unit coils is performed on the inner circumferential side and the outer circumferential side of the coil. As compared with the conventional coil in which a connecting portion extending in the radial direction of the coil is arranged, the distance between adjacent unit coils can be narrowed and the axial dimension of the coil can be reduced. Therefore, according to the present invention, it is possible to reduce the size of the coil by taking advantage of the characteristic that the coil occupying ratio of the conductor, which is provided in the coil winding structure formed of the thin plate conductor, is large.
[0062]
According to the manufacturing method of the present invention, a set coil is manufactured by connecting two unit coils having different winding directions to each other and connecting the inner peripheral terminals of both unit coils to each other. Since the coils are arranged by arranging a plurality of coils, the terminals on the inner peripheral side of the unit coils constituting each set coil are connected in the window of one of the unit coils, and the interval between the unit coils is set. And the axial dimension of the coil can be reduced.
[Brief description of the drawings]
FIGS. 1A and 1B are cross-sectional views showing a first unit coil and a second unit coil used in the present invention. (C) is an explanatory view for explaining the structure of the terminal portion of the coil.
FIG. 2 is a cross-sectional view of a coil for a molded transformer according to the present invention.
FIG. 3 is a perspective view showing an example of an insulating structure of a thin plate conductor used for winding a coil of the present invention.
FIG. 4 is a perspective view showing another example of the insulating structure of the thin plate conductor used for winding the coil of the present invention.
FIG. 5 is a cross-sectional view showing a structure of the thin plate conductor shown in FIG.
FIG. 6 is a perspective view showing two unit coils used to configure a group coil in the embodiment of the present invention.
7 is a perspective view showing a state where one end portion of the unit coil of FIG. 6 is bent and the end portion is pulled out in a winding axis direction.
8 is a perspective view showing a state in which terminal units on the inner peripheral side of the two unit coils shown in FIG. 7 are connected to form a combined coil.
FIG. 9 is a perspective view showing a state in which a plurality of coil groups are arranged to form a coil according to the present invention.
FIGS. 10A and 10B are explanatory diagrams showing different examples of how the terminal portion of the unit coil is bent.
FIG. 11A is a cross-sectional view showing a welded portion on one unit coil side of a modified example of a cross connection portion connecting between inner peripheral side terminals of adjacent unit coils, and FIG. (C) is a cross-sectional view showing a welded portion on the other unit coil side of the modified example.
FIG. 12 is a perspective view showing a main part of another modified example of a crossover connecting portion for connecting between inner peripheral side terminals of adjacent unit coils.
FIG. 13 is a cross-sectional view showing a conventional coil for a molded transformer.
[Explanation of symbols]
10A: a first unit coil, 10B: a second unit coil, 11: a thin plate conductor, 12A, 12B: an inner peripheral terminal, and 13A, 13B: an outer peripheral terminal.

Claims (8)

A plurality of unit coils are arranged side by side in the winding axis direction to form a unit coil group, and a series of unit coils constituting the unit coil group are sequentially connected in series to form a single coil for a molded transformer. In the coil,
Each unit coil has a structure in which a predetermined number of turns are continuously wound with a strip-shaped thin plate conductor insulated between layers,
A series of unit coils constituting the unit coil group are arranged in a state where winding directions of adjacent unit coils are alternately changed,
The series of unit coils connect a transition connection portion that connects a winding end and a winding start of an adjacent unit coil on an inner peripheral side of the coil and a winding end and a winding start of an adjacent unit coil on an outer peripheral side of the coil. That the connecting portions are connected in series by a connecting structure that is alternately arranged in the winding axis direction,
A coil for a molded transformer. A set coil having a structure in which two unit coils are arranged side by side in the winding axis direction with their respective winding directions being different, and are connected to each other by connecting portions across end portions on the inner peripheral side of both unit coils. Are arranged in the winding axis direction to form a unit coil group,
Terminal units on the outer peripheral side of adjacent unit coils of adjacent unit coils of the unit coil group are connected to each other by a cross connection unit, and a series of unit coils are connected in series.
Each of the unit coils has a structure in which a predetermined number of turns are continuously wound in a state where a strip-shaped thin plate-shaped conductor is insulated between layers,
A coil for a molded transformer. An insulating tape is wrapped around the thin conductor constituting each unit coil, and the thin conductor is covered with the insulating tape,
The coil for a molded transformer according to claim 1 or 2, wherein insulation between layers of each unit coil is provided by the insulating tape. Insulating paper is placed in a state of being attached to one surface of the thin conductor constituting the unit coil, and an insulating tape is roughly wound around a polymer of the insulating paper and the thin conductor,
The coil for a molded transformer according to claim 1 or 2, wherein insulation between layers of each unit coil is provided by the insulating paper. The coil for a molded transformer according to claim 1 or 2, wherein insulation between layers of the unit coil is provided by interlayer insulating paper wound together with the thin-plate conductor. In each of the crossover connection portions, one terminal portion of adjacent unit coils connected to each other by each crossover connection portion is bent toward the terminal portion side of the other unit coil, and one of the bent unit coils is bent. The coil for a molded transformer according to any one of claims 1 to 5, wherein the terminal of (1) is overlapped with and connected to the terminal of the other unit coil. In each of the connecting portions, one terminal portion of one of the adjacent unit coils connected to each other by the connecting portion is bent once and then bent toward the terminal portion side of the other unit coil. The extreme end of the unit coil is further bent along the longitudinal direction of the terminal of the other unit coil, and the extreme end of the one unit coil is overlapped and connected to the terminal of the other unit coil. A coil for a molded transformer according to any one of claims 1 to 5. A method for manufacturing a coil for a molded transformer, in which a number of unit coils arranged in the winding axis direction are sequentially connected in series to form one coil,
A unit coil winding step of winding a unit coil by continuously winding a predetermined number of turns in a state where a strip-shaped thin plate conductor is insulated between layers;
The two unit coils wound in the unit coil winding step are arranged side by side in the winding axis direction in a state where the winding directions are different from each other, and a terminal portion on the inner peripheral side of one unit coil is arranged. Is connected to the terminal portion on the inner peripheral side of the other unit coil to produce a group coil manufacturing process,
A set coil connection step of arranging a plurality of set coils manufactured in the set coil manufacturing step and connecting the terminal portions of adjacent set coils across the outer circumference of the coil,
A method for manufacturing a coil for a molded transformer.

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