JP2005085560A - Litz wire coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a litz wire coil in which the stability of coil shape and compactness are realized and also the difference of potential between the adjoining litz wires of the coil layer is made minimum. <P>SOLUTION: A square litz wire 11 having a rectangular cross section is wound so as to be vertically piled, and the whole shape is formed in a rectangular parallelepiped. The square litz wire 11 is formed in rectangular cross section by dies of a prescribed shape or a rolling roller or the like. The method of square shaping of the litz wire includes such as (1) the litz wire is formed in square shape before forming of coil and this square litz wire is formed in a coil, (2) the litz wire is shaped in square simultaneously as coil shaping, and (3) a round bundled litz wire is shaped in a coil and this formed coil is formed in square shape in one lot. The square litz wire coil 10 is not necessarily limited to one formed by one square litz wire 11, but that it may be constructed by using a plurality of pieces of square litz wires. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a litz wire coil using a square litz wire as a magnetic flux generating means required in an electromagnetic induction system.

Among electric appliances having a heating (heat generation) system, an electromagnetic induction heating method has started to be widely used for the purpose of energy saving and efficiency improvement.
Coils are widely used for all purposes. Among them, coils used for electromagnetic induction heating are required to be used at high frequencies. An electric wire used as a high-frequency coil is more advantageous as a double wire (for example, a bundled wire) than a single wire as long as the total cross-sectional area is the same. It is more advantageous to use a wire rod having a small strand diameter and a large number of bundles, such as a litz wire (see Patent Document 1).
FIG. 17 shows a conventional litz wire coil obtained by winding a litz wire (round bundle litz wire) 9 having a circular cross section around a winding drum 9 times. A conventional general-purpose type litz wire coil is formed by winding an ordinary round bundle litz wire around a winding form by hand winding or a simple winding machine.
JP 2000-215972 A

By the way, the above technique has the following problems to be solved.
Litz wires with a small strand diameter and a large number of bundles are troublesome to place each strand at a predetermined position when forming a coil using a mold, and the strands can be unwound before coil formation. Handling is difficult because the coil shape is not stable. If the coil shape is not stable, the basic electrical characteristics of the coil will not be stable. In addition, the apparent volume (the apparent diameter of the bundled wire) is increased due to the influence of the insulation film of the strands compared to the single wire. In order to improve the performance of a litz wire coil (decrease in DC resistance, increase in inductance, etc.), one method is to suppress coil volume increase, that is, to make the coil compact.

  Moreover, the coil using the round bundle litz wire 9 shown in FIG. 17 has a large cross-sectional area (volume) and an extremely low space factor that affects the coil performance. In addition, since such a conventional type coil has a certain degree of limitation in its manufacturing method, a potential difference between adjacent litz wires of the coil layer, for example, at the position of numeral 1 indicating the winding order in FIG. The potential difference between the litz wire and the litz wire at the same number 7 position or the potential difference between the litz wire at the same number 5 position and the litz wire at the same number 9 position is large, and the possibility of a short circuit is increased. There is a difficulty that it ends up.

  An object of the present invention is to provide a litz wire coil that stabilizes the coil shape and is compact, and minimizes the potential difference between adjacent litz wires of a coil layer.

The present invention solves the above problems by the following configuration.
<Configuration 1>
A litz wire coil, characterized in that rectangular litz wires are wound so as to be stacked vertically in the axial direction, and the overall shape is formed into a rectangular parallelepiped shape.

The square litz wire is formed into a square or a rectangular cross section by a predetermined shape die or a rolling roller. Vertical stacking refers to stacking square litz wires so that their flat portions overlap one another.
By forming a coil with a square litz wire, the coil shape is stabilized and the basic electrical characteristics of the coil can be stabilized. In addition, the coil volume can be made compact, and the electrical performance can be improved by reducing the DC resistance, increasing the inductance, and the like.
There are the following three ways to square the litz wire. (1) Before forming the coil, the litz wire is squared and the rectangular litz wire is coiled. (2) Coil molding at the same time that the litz wire is squared. (3) A round bundle litz wire is coil-molded, and the molded coil is batch-rectified. In addition, as a round bundle litz wire used at this time, the thing which carried out the collective twist of the several litz wire is preferable, However, the well-known compound twist may be used.
The Litz wire coil of Configuration 1 is used for various purposes. For example, when the Litz wire coil is used as a heat source for electromagnetic induction heating by being fitted into a frame of a predetermined shape, the frame is heated to a high temperature of about 240 to 260 ° C. It is good to shape | mold with any high heat-resistant resin, such as PPS resin (polyphenylene sulfide), PEEK resin (polyether ether ketone), liquid crystal resin, etc.

<Configuration 2>
The litz wire coil according to the first aspect, wherein the rectangular litz wire is wound in a radial direction to form a multi-layer winding.

  Depending on the characteristics required of the coil, the single layer type as shown in FIG. For example, when it is desired to increase the thickness of the coil in the radial direction, or when it is desired to make the litz wire used to be compatible with the 200 volt specification with respect to the 100 volt specification, for example. When a normal round bundle litz wire is formed into a square shape, there is an allowable range (a constant flatness ratio) that can be squared (flattened), which needs to be taken into consideration. Since the square shape exceeding the allowable range is very difficult except for some special manufacturing conditions, a multi-layered vertical coil having two or more layers wound in the radial direction is formed.

<Configuration 3>
A litz wire coil according to the construction 2, wherein the litz wire portion at the intersection of the rectangular litz wires is flattened in the axial direction by loosening the tension and pulling it back slightly.

  The Litz wire coil of the configuration 3 is configured by actively breaking the bundle of litz wires at the intersection of the square litz wires. Since the intersection of the square litz wire has a shape protruding only in the axial direction, the fit as a product is poor, and there is a possibility that the wire may be disconnected when it is forcibly compression-molded. By adopting the configuration 3, the square litz wire coils have almost the same height in the axial direction over the entire surface including the intersection of the litz wires, and pressure is applied to each strand at the intersection of the square litz wires. By being in a relaxed state, the wire breakage due to compression molding is prevented.

<Configuration 4>
The Litz wire coil according to Configuration 2, wherein the square Litz wire is wound in two layers in the order of an outer layer, an inner layer, an inner layer, an outer layer, an outer layer, and an inner layer and vertically stacked.

  The Litz wire coil of configuration 4 starts winding the square litz wire from the outer layer, and then winds the inner layer in the same row. Next, by winding the inner layer of the second row along the axial direction, winding the outer layer of the two rows, and then winding the outer layer of the third row up to a predetermined row in the order, A two-layer structure in which no intersection occurs.

<Configuration 5>
The Litz wire coil according to Configuration 2, wherein the rectangular Litz wire is wound in two layers in the order of an inner layer, an outer layer, an outer layer, an inner layer, an inner layer, and an outer layer, and vertically stacked.

  The Litz wire coil of configuration 5 starts winding the rectangular Litz wire from the inner layer, and then winds the outer layer in the same row. Next, by winding the outer layer of the second row along the axial direction, winding the inner layer of the two rows, and then winding the inner layer of the third row up to a predetermined row in the order, A two-layer structure in which no intersection occurs.

<Configuration 6>
A litz wire coil, wherein a plurality of rectangular litz wires are wound so as to be vertically stacked in a state of being arranged in parallel, and the overall shape is formed into a rectangular parallelepiped shape.

  This type of coil can reduce the axial height and increase the inductance.

<Configuration 7>
The Litz wire coil according to any one of the constitutions 1 to 6, wherein a heat resistant pressing tape formed by adding a heat resistant adhesive material to a heat resistant base substrate is wound around an arbitrary place around the Litz wire coil.

  The litz wire coil tends to break the wire after molding. By winding the heat-resistant presser tape, the coil shape is maintained and the workability and electrical performance are stabilized during molding and after assembling to other parts or when used as a product.

<Configuration 8>
The litz wire coil according to any one of the constitutions 1 to 7, wherein a concave portion or a convex portion is provided at a central portion on a short side.

  The Litz wire coil of configuration 8 is effective when a heated cylindrical body made of magnetic metal is inserted into a concave portion or a convex portion and arranged in the closest state for induction heating.

  Hereinafter, embodiments of the present invention will be described using specific examples.

  Fig.1 (a) is a perspective view which shows the 1st Example of the litz wire coil of this invention. FIGS. 1B and 1C are explanatory views of a method for forming the square litz wire shown in FIG. FIG. 2 is a cross-sectional view of the litz wire coil shown in FIG.

  The litz wire coil 10 of this embodiment is a single layer vertically stacked coil formed by winding and forming a square litz wire 11 having a square cross section (rectangular cross section). That is, the rectangular litz wire 11 is formed by pressing the round bundle litz wire 9 shown in FIG. 1 (b) with a well-known mold or a pressure roller (not shown) and having a rectangular cross section shown in FIG. 1 (c). It is molded into Such a rectangular litz wire 11 is vertically stacked in an axial direction by edgewise winding to form a single-layer litz wire coil 10 whose overall shape is a rectangular parallelepiped shape, that is, a rectangular litz wire single-layer vertically stacked coil. doing. Edgewise winding refers to winding a square litz wire with the short side (edge) side of its rectangular cross section facing the winding drum.

  A presser tape 12 is wound around an arbitrary portion around the litz wire coil 10. The presser tape 12 is for holding a predetermined coil shape of the molded litz wire coil 10 temporarily or over a long period of time, and is preferably heat resistant and thin. When a well-known self-bonding tape is used as the presser tape 12, it can be considered that it cannot be used in a use environment exceeding 150 ° C. Accordingly, when the Litz wire coil 10 is used at a high temperature of 200 to 220 ° C. and the presser tape 12 is required to have high heat resistance, for example, Kapton (polyimide), Teflon (registered trademark), Nomex tape A tape obtained by adding a heat-resistant adhesive material such as a silicone resin or an acrylic resin to a heat-resistant base substrate such as a resin is used.

FIG. 3 is a cross-sectional view showing a two-layered vertical coil according to the second embodiment of the present invention.
A two-layer vertical product type coil 20 shown in FIG. 3 is formed into two layers in the radial direction using one square litz wire 21. This square litz wire 21 has a width that is 1/2 of the thickness t of the litz wire coil 10 shown in FIG. The thickness t refers to the length in the radial direction in the coil cross section.

FIG. 4 is a cross-sectional view showing a two-layered vertical coil according to a third embodiment of the present invention.
The two-layer vertically stacked coil 30 shown in FIG. 4 has two layers in the radial direction using a single rectangular litz wire 31 having a width equal to the thickness t of the litz wire coil 10 shown in FIG. Molded.

  A multilayer vertical stack type coil having two or more layers may have a crossing problem between the inner layer and the outer layer, which is not regarded as a problem in the single-layer coil molding. The crossing of litz wires (FIG. 7) needs to be avoided as much as possible because it may cause the wire to break during molding. When a two-layer type is taken as an example for forming a normal multi-layered vertical coil, a method of forming a coil structure in which inner layers, outer layers, inner layers, and outer layers are alternately stacked is the easiest. However, in this coil structure, an intersection (cross point) 13 between the inner layer and the outer layer exists for each turn. Accordingly, a multilayer vertically stacked coil having the structure shown in FIG. 5 is proposed.

FIG. 5 is an explanatory view showing a fourth embodiment of the present invention in a lateral cross section.
The square litz wire 11 is configured as follows so that the intersection 13 between the inner layer and the outer layer as shown in FIG. 7 does not occur every turn. That is, in FIG. 5 attached with numerals 1 to 8 indicating the winding order of the square litz wire 11, first, the square litz wire 11 is started to be wound from the outer layer 1. Next, the inner layer 2 in the same row is wound. Next, by winding the inner layer 3 in the second row, winding the outer layer 4 in the second row, and then winding the outer layer 5 in the third row up to a predetermined row, the intersection of the square litz wires Can be prevented from occurring. Alternatively, the rectangular litz wire is wound from the inner layer, and then the outer layer in the same row is wound. Next, the outer layer in the second row, the inner layer, the inner layer in the third row, and the outer layer may be wound in two layers and stacked vertically. Such a structure takes time for molding, and is therefore implemented in special circumstances.

FIG. 6 is an explanatory view showing a fifth embodiment of the present invention in a cross section on one side.
In this embodiment, there is an intersection of square litz wires, but the bundle of square litz wires 11 at the intersection is actively broken. That is, the portion other than the intersection is aligned and wound, but the portion at the intersection of the litz wire 11 is loosened slightly and pulled back slightly to be spread laterally as shown in FIG. The square litz wire coil formed in this way has substantially the same axial height over the entire surface including the intersection of the litz wire 11.
By doing so, it is possible to form a square litz wire multilayer vertically stacked coil that can reduce damage to the strands at the intersection even if there is an intersection of the square litz wire.

  The square litz wire coil shown in each of the above embodiments is formed by one square litz wire, but the present invention is not limited to this. Next, the square litz wire coil of the present invention configured using a plurality of square litz wires will be described.

FIG. 8 is a perspective view showing a sixth embodiment of the present invention, and FIGS. 9 to 11 are explanatory views of the sixth embodiment.
The embodiment shown in FIG. 8 uses three rectangular litz wires, and these are stacked vertically in the axial direction by edgewise winding with the wide surfaces arranged in a horizontal row, and the overall shape is formed into a rectangular parallelepiped shape. This is a three-layered vertical coil.
The use of a plurality of square litz wires is a case where it is difficult to mold with only one square litz wire, but in the experiment, good results were obtained under the following conditions.

  That is, as shown in FIG. 9, when forming the square litz wire 9 into a square shape when forming with a single square litz wire, the width is a and the height is b. Prepare two round bundle litz wires 9A in which the number of twists of the litz wire shown in FIG. 10 is half each of the round bundle litz wires 9 shown in FIG. 9, and these two round bundle litz wires 9A are The width of the two square litz wires 11A when formed into a square shape is 1.43a and the height is 0.7b. The square litz wires 11A thus formed are stacked in multiple layers in parallel.

Further, as shown in FIG. 11, three round bundle litz wires 9B in which the number of twists of the litz wire is divided into 1/3 of the round bundle litz wire 9 shown in FIG. 9 are prepared. When the round bundle litz wire 9B is molded into a square shape, the width of the three square litz wires 11B is 1.74a and the height is 0.57b. The Litz wire coil shown in FIG. 8 is obtained by arranging the rectangular litz wires 11B thus arranged in parallel and vertically stacking three layers.
By doing so, a single litz wire that has exceeded the allowable range for squareness is divided into two or more, so that the apparent flatness can be increased. Finally, since these two or more square litz wires are connected outside the coil, the electrical resistance can be the same as that of one coil.

FIG. 12 is a perspective view showing a seventh embodiment of the present invention, and FIG. 13 is a transverse sectional view showing a use state of the embodiment.
The litz wire coil 10A shown in FIG. 12 has a rectangular parallelepiped shape as a whole, and is provided with a concave portion 14A at the central portion on the short side of the upper surface of the coil. The recess 14A has a V shape and is not shown in the figure, but is also provided at the center of the short side opposite to the coil.
Such a litz wire coil 10A is molded, for example, as follows. That is, a litz wire coil having an overall shape as shown in FIG. 1 and a rectangular parallelepiped shape is housed in a holding mold having a size equivalent to the outer shape of the litz wire coil. Next, the concave portion 14A is formed by pressing a pressing die having a convex portion complementary to the concave portion 14A at the central portion on the short side of the plane of the coil.

  The litz wire coil 10A thus molded is used as follows. That is, the heated cylindrical body made of magnetic metal is disposed in the state of being closest to the concave portion 14A. Due to the presence of the recess 14A, the heated cylindrical body can be fitted into the recess 14A and disposed closer to the coil. The magnetic lines of force generated from the litz wire coil 10A when energized cross the heated cylindrical body and perform electromagnetic induction heating more effectively.

Further, the litz wire coil 10A is provided with a convex portion 14B at the central portion on the short side of the lower surface of the coil. The convex portion 14B protrudes in a V shape corresponding to the concave portion 14A, and although not shown, it is also provided at the central portion of the opposite short side of the coil.
For example, such a litz wire coil 10A is inserted into a heated cylindrical body made of magnetic metal when used, and the convex portion 14B is arranged in a state of being closest to the circumferential surface at an arbitrary position of the heated cylindrical body. In this case, the electromagnetic induction heating is more effectively performed as in the case of the recess 14A described above.

FIG. 13 to FIG. 15 are cross-sectional views simply showing modifications of the seventh embodiment.
In the litz wire coil 10B shown in FIG. 13, the recess 15A is provided in a V shape including the long side.
Compared with the litz wire coil 10 </ b> A shown in FIG. 12, the heated cylindrical body 15 having a larger outer diameter can be handled.

  The litz wire coil 10C shown in FIG. 14 is provided with a concave portion 16A that forms an arc.

In the litz wire coil 10D shown in FIG. 15, the concave portion 17A is provided in an arc shape including the long side.
Compared with the litz wire coil 10 </ b> C shown in FIG. 14, it can correspond to a heated cylindrical body having a larger outer diameter.

FIG. 16 is a transverse sectional view showing an eighth embodiment of the present invention.
The litz wire coil 10E shown in FIG. 16 has a rectangular parallelepiped shape, and has a curved shape so that both side surfaces 18 bulge outward. Such a litz wire coil 10E may be formed by winding a rectangular litz wire 11E having a different thickness t, but after winding a rectangular litz wire 11E having a constant thickness t, a mold or the like is used. As shown in the figure, both sides may be curved and molded.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the 1st Example of the litz wire coil of this invention, (a) is a perspective view which shows the whole structure, (b) is explanatory drawing which shows the state before the square shaping | molding process of a square litz wire, c) is a cross-sectional view showing a square litz wire. It is a cross-sectional view of the litz wire coil shown in FIG. It is a cross-sectional view showing a second embodiment of the present invention. It is a cross-sectional view showing a third embodiment of the present invention. It is a cross-sectional view showing a fourth embodiment of the present invention. It is a cross-sectional view showing a fifth embodiment of the present invention. It is explanatory drawing of the crossing situation of a square-shaped litz wire. It is a perspective view which shows the 6th Example of this invention. It is explanatory drawing of the 6th Example of this invention. It is explanatory drawing of the 6th Example of this invention. It is explanatory drawing of the 6th Example of this invention. It is a perspective view which shows the 7th Example of this invention. It is explanatory drawing of the modification in a 7th Example. It is explanatory drawing of the other modification in a 7th Example. It is explanatory drawing of the other modification in the 7th Example. It is a cross-sectional view showing an eighth embodiment of the present invention. It is explanatory drawing of the conventional litz wire coil.

Explanation of symbols

9 Round bundle Litz wire 10 Litz wire coil 11 Square litz wire 12 Press tape 13 Intersection 14A, 15A, 16A, 17A Concave portion 14B Convex portion 20, 30 Multi-layer vertically stacked coil 21, 31 Square litz wire

Claims (8)

  A litz wire coil, characterized in that rectangular litz wires are wound so as to be stacked vertically in the axial direction, and the overall shape is formed into a rectangular parallelepiped shape. The litz wire coil according to claim 1,
A litz wire coil, wherein the square litz wire is wound in a radial direction to form a multi-layer winding. In the litz wire coil according to claim 2,
A litz wire coil, wherein the litz wire portion at the intersection of the square litz wires is flattened in the axial direction by loosening the tension and pulling it back slightly. In the litz wire coil according to claim 2,
A litz wire coil, wherein the rectangular litz wire is wound in two layers in the order of an outer layer, an inner layer, an inner layer, an outer layer, an outer layer, and an inner layer and stacked vertically. In the litz wire coil according to claim 2,
A litz wire coil, wherein the rectangular litz wire is wound in two layers in the order of an inner layer, an outer layer, an outer layer, an inner layer, an inner layer, and an outer layer and stacked vertically.   A litz wire coil, wherein a plurality of rectangular litz wires are wound so as to be vertically stacked in a state of being arranged in parallel, and the overall shape is formed into a rectangular parallelepiped shape. In the litz wire coil according to any one of claims 1 to 6,
A litz wire coil, characterized in that a heat-resistant press tape formed by adding a heat-resistant adhesive material to a heat-resistant base substrate is wound around an arbitrary place around. In the litz wire coil according to any one of claims 1 to 7,
A litz wire coil, wherein a concave portion or a convex portion is provided in a central portion on a short side.

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