JP4824508B2 - Litz wire coil - Google Patents

Description

  The present invention relates to a litz wire coil used in a heat generating device or the like that employs an electromagnetic induction heating method.

  Conventionally, this type of Litz wire coil is manufactured by winding a litz wire formed by bundling a predetermined number of insulating wires and twisting them at a predetermined pitch (see Patent Document 1). Although the coil is widely used for all purposes, the coil used in the electromagnetic induction heating is required to be used at a high frequency (see Patent Document 2).

  Generally, an induction heating coil used in a high frequency region is preferably a coil having high inductance and low electrical resistance. When the electrical resistance is the same, self-inductance (hereinafter simply referred to as inductance) is used. It is possible to improve the coil performance by increasing. It has been found that the inductance is proportional to the square of the number of turns of the coil and the cross-sectional area when the axial length of the coil is constant.

Here, consider the case where the coil configuration is described in the following (1) to (5).
(1) A litz wire is wound on a plane perpendicular to the coil axis direction.
(2) The shape of the innermost coil layer is the same.
(3) The electric resistance is constant.
(4) The number of coil turns is constant.
(5) The coil length (in the case of (1) above, the coil thickness) is made constant.

In order to obtain a high inductance in such a case, it is necessary to make the coil cross-sectional area as large as possible. If the electrical resistance and the number of turns are not restricted, the litz wire may be wound largely to the allowable limit of the coil outer diameter. However, when both the electrical resistance and the number of turns are restricted, a method of roughly winding the litz wire to the allowable limit of the coil outer diameter is required.
JP-A-1-294305 JP 2000-215972 A

  Considering the effect of the skin effect when used in a high frequency range, it is desirable to use a litz wire with a small outer diameter of the insulation element wire, but the handling property is extremely poor when rough winding as described above is performed. It is very difficult to wind the litz wire with a certain interval due to the effect of the twisting of the litz wire itself. Even if it can be wound, the coil shape is extremely unstable and lacks reproducibility.

  The present invention has been made paying attention to the above points, and an object of the present invention is to provide a litz wire coil that can obtain a high inductance and a stable coil shape.

In each embodiment of the present invention, the above-described problems are solved by the following configurations.
<Configuration 1>
A litz wire coil formed by winding a plurality of litz wires in which a number of insulating strands are twisted, and a spacer having substantially the same length as the litz wire and not energized is arranged in parallel with the litz wire. A litz wire coil that is coiled in a state.

  Since the gap can be prevented from being generated in the coil by winding the spacer in parallel with the litz wire, a high inductance can be obtained and a stable coil shape can be obtained. The spacer having this configuration has substantially the same cross-sectional shape as the litz wire. Here, the non-energized spacer includes not only a spacer made of an electrically insulating material, but also a spacer made of a conductive metal material such as copper or aluminum, which is an electric circuit opened at the time of use.

<Configuration 2>
A litz wire coil formed by winding a plurality of litz wires obtained by twisting a number of insulating strands, wherein the litz wires are formed by twisting the insulating strands and a non-energized spacer. Litz wire coil.

  By using the litz wire whose apparent volume is increased by the spacer, it is possible to prevent the gap from being generated in the coil, so that a high inductance can be obtained and a stable coil shape can be obtained. The spacer having this configuration has substantially the same cross-sectional shape as the insulated wire. In addition, the non-energized spacer in this configuration is not only a spacer made of an electrically insulating material, but also a spacer made of a conductive metal material such as copper or aluminum, and is electrically insulated from the insulated wire during use, and Includes a spacer that is an open electrical circuit.

<Configuration 3>
The Litz wire coil according to Configuration 1 or 2, wherein the spacer is a linear body made of a material having heat resistance and insulation.

  As an induction heating coil, stable electrical characteristics can be maintained at high temperatures.

<Configuration 4>
4. The Litz wire coil according to any one of configurations 1 to 3, wherein the litz wire and the spacer are wound in parallel in the coil radial direction.

<Configuration 5>
4. The Litz wire coil according to any one of configurations 1 to 3, wherein the Litz wire and the spacer are vertically stacked in the coil axial direction by edgewise winding in a state of being arranged in parallel.

  A vertically stacked litz wire coil with a stable shape can be obtained.

<Configuration 6>
The litz wire coil according to any one of configurations 1 to 5, wherein the litz wire and the spacer are each formed into a square cross section.

  Hereinafter, embodiments of the present invention will be described in detail for each example.

FIG. 1 is an explanatory diagram illustrating a part of the litz wire coil according to the first embodiment.
As shown in FIG. 1A, the litz wire coil 10 of the first embodiment is a combination of a litz wire 12 and a spacer 14 wound in parallel in the coil radial direction. That is, a unit in which the litz wire 12 and the spacer 14 are combined in parallel is defined as one unit, and this is wound in parallel in the coil radial direction, for example, three times.

  As shown in FIG. 1B, the litz wire 12 is a square litz wire formed by twisting a number of insulating element wires 16 at an appropriate pitch into a square cross section. The spacer 14 has a length and a cross-sectional shape substantially the same as the litz wire 12, and is a linear body made of a material having appropriate heat resistance, insulation, and flexibility.

  By the way, it is possible to increase the inductance of the coil by increasing the apparent volume of the coil. A wide range of coils is required to obtain as much inductance as possible. However, for example, as shown in FIG. 2, as with the conventional litz wire coil 10 </ b> A, the litz wire 12 is wound tightly by simply winding the litz wire 12, so that high inductance cannot be obtained. Therefore, in order to make it as wide as possible, the inductance becomes large when the litz wire 12 is wound roughly like the litz wire coil 10B shown in FIG. Become.

  Since the litz wire coil 10 shown in FIG. 1A is combined with the litz wire 12 and the spacer 14 and wound in parallel, no gap is generated in the coil, so that a stable coil shape can be obtained. And it becomes possible to enlarge an inductance. That is, it is possible to provide a coil whose shape is extremely stable as compared with the case where the litz wire 12 is simply loosely wound.

The spacer 14 that can be employed here has the following conditions (1) to (3).
(1) Have heat resistance.
(2) Have flexibility.
(3) Have insulation.

The condition (1) will be described.
Since the induction heating coil is used at a high temperature, the rated temperature is often determined in the specification of the material used. Although the required specifications are wide within a temperature range of 300 ° C. or lower, resin materials with high heat-resistant temperatures are often expensive, and it is necessary to appropriately select the materials according to the specifications. Examples of the heat resistant resin material include PPS, polyetherimide, PFA, unsaturated polyester, high heat resistant phenol, and polyimide.

The condition (2) will be described.
Since the spacer 14 is wound together with the litz wire 12 to be bent, cracking occurs if there is no flexibility. Material selection according to the coil shape is required.

The condition (3) will be described.
It is desirable to have an insulating property, and it is not a necessary condition. However, it is safer that the litz wire 12 used for the coil is subjected to an insulation treatment with an enamel film, and the spacer 14 disposed between the litz wires 12 also has insulation properties. As the spacer 14, a metal material may be used regardless of the resin material. However, use of a material having a high magnetic permeability such as iron has an effect on characteristics, so it is desirable to use copper or aluminum having a low magnetic permeability. Naturally, even if a metal is used here, it is not energized as a coil, so it is necessary to make it an open electric circuit.

FIG. 4 is an explanatory view showing a part of the litz wire coil of the second embodiment.
As shown in the drawing, the Litz wire coil of Example 2 is a litz wire coil formed by winding a plurality of litz wires 19 obtained by combining and twisting a number of insulating wires 16 and spacers 18. The litz wire 19 is a rectangular litz wire formed by twisting a large number of insulating wires 16 and spacers 18 at an appropriate pitch into a square cross section. The spacer 18 has substantially the same length and cross-sectional shape as the insulating wire 16 and is made of a material having heat resistance, insulation and flexibility similar to the above conditions (1) to (3). It is a linear body.

  Similarly to the litz wire coil of the first embodiment, this litz wire coil uses the litz wire 19 whose apparent volume is increased by the spacer 18 and has a large inductance and a good coil performance. A stable coil shape can be obtained.

FIG. 5 is a perspective view showing the litz wire coil of the third embodiment. 6A is a cross-sectional view of the litz wire coil of this embodiment, and FIG. 6B is a cross-sectional view of another litz wire coil.
The Litz wire coil 20 shown in FIG. 5 is a three-layered vertical coil using three sets 22 of litz wires and spacers. In this coil, each set of litz wire and spacer set 22 is arranged in parallel, and a pair of litz wire and spacer lead wire 22A are provided at both ends. In addition, as shown in FIG.1 (b), each set of litz wire is a square litz wire formed by twisting a large number of insulating wires at an appropriate pitch and forming a rectangular cross section. Each set of spacers has substantially the same cross-sectional shape and length as the litz wire.

  As shown in FIG. 5 and FIG. 6A, the litz wire coil 20 has three sets of square litz wires and spacers in the coil axial direction (in the direction of arrow 26) with edgewise winding in a state where wide surfaces are arranged in a horizontal row. ) And the entire shape is molded into a rectangular parallelepiped shape. A presser tape 24 is wound around an arbitrary portion around the coil. The presser tape 24 is for holding the molded litz wire coil 20 temporarily or over a long period of time, and is preferably heat resistant and thin. Further, as shown in FIG. 6B, the litz wire coil 20 is wound in a direction (arrow 27 direction) perpendicular to the coil axis direction in a state in which square litz wires and spacers are arranged in the coil axis direction. The shape may be molded into a rectangular parallelepiped shape.

  Even such a litz wire coil 20 is a litz wire having an apparent volume increased by the spacer, and the coil inductance can be increased. Note that the litz wire / spacer set 22 may be replaced by a litz wire 19 in which a number of insulating element wires 16 and spacers 18 shown in FIG.

FIG. 3 is an explanatory diagram illustrating a part of the litz wire coil according to the first embodiment. It is explanatory drawing which shows a part of conventional litz wire coil. It is explanatory drawing which shows a part of other conventional litz wire coil. FIG. 6 is an explanatory diagram illustrating a part of a litz wire coil according to a second embodiment. It is a perspective view which shows the litz wire coil of Example 3. It is explanatory drawing of the litz wire coil of Example 3. FIG.

Explanation of symbols

10 Litz wire coil 12 Litz wire 14 Spacer 16 Insulated wire 18 Spacer 19 Litz wire

Claims (2)

A litz wire coil that is formed by twisting a number of insulating strands into a square shape with a transverse cross section and winding in parallel in the coil radial direction by combining a linear spacer that is not energized ,
The spacer is a linear body made of copper or aluminum, and is molded into a rectangular cross section having substantially the same length and substantially the same shape as the square litz wire ,
One unit is a combination of the spacers arranged in parallel with the square litz wire,
A litz wire coil, wherein one unit or a plurality of units are wound in parallel in the coil radial direction with no gap between them. In the litz wire coil according to claim 1,
A litz wire coil, wherein the square litz wire and the spacer are vertically stacked in the coil axial direction by edgewise winding in a state where they are arranged in parallel .

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