JP2011060436A - Induction heating coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating coil having less loss and high efficiency, being small in size, and simple structure and being easily manufactured. <P>SOLUTION: An electric wire 2 is cut to a predetermined length, in which an insulating body 2b collectively covers the outer periphery of a composite conductor in which a plurality of adjoining conductors 2a are contacted with each other and arranged parallel to one another. Then, since the electric wire is wound into a ring from, in order to secure and reinforce the bundle of electric wire wound into a ring form, a binding tape 4 is pasted to four points on the outer periphery of the bundle of electric wire and is secured finally on a base material 3 that consists of a double-sided tape. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an induction heating coil used in an induction heating apparatus such as an IH rice cooker.

As shown in FIG. 3 and FIG. 4 as a conventional induction heating coil, an electric wire bundle in which a heat-resistant resin electric wire is wound in an annular shape is bound with a fixing tape and pasted on a base material such as a double-sided tape. Heating coils are known. And according to the specification of the induction overheating device, the induction heating coils are connected in a plurality of layers to adjust the strength of the generated magnetic field. (In order to form a plurality of layers, a structure using a double-sided tape is used between the coils. The double-sided tape is arranged between the upper coil and the lower coil in FIG. 4).
However, if the induction heating coil has a multi-layered structure in a plurality of layers, the inductance or DC resistance of the coil increases, and the impedance becomes larger than that of a single layer, so that the required magnetic field cannot be obtained and loss is lost. There was a problem that heating efficiency was large and low.
Further, the multilayer structure described above has a problem in terms of space that cannot be multilayered as much as expected because the thickness of the double-sided tape as the base material and the thickness of the fixed tape are added.
Thus, as a method for solving this problem, an induction heating coil has been proposed in which a plurality of wire coils, which are strands coated with an insulator, are arranged in a vertical direction and wound in a spiral shape. (Patent Document 1)

However, even in this proposed method, since the wire coil itself, which is a wire, is covered with an insulator, there is a limit to arranging the insulator in the vertical direction depending on the thickness of the insulator, and a space is taken in the vertical direction. There is also a problem that a predetermined magnetic field cannot be obtained with a device that does not, or that a coil cannot be installed in the device.
Also, in this method, since the strands are covered with an insulator, it is necessary to bond after removing or stripping the covering layer of the strands at both ends in order to bond the strands arranged in parallel. There is a problem in the manufacturing process that it takes time.
Furthermore, in order to couple the strands arranged in parallel at both ends, a coupling member such as a crimping terminal is required, which complicates the configuration, and the strands arranged in parallel are coupled only at both ends. Therefore, there are concerns about problems related to product reliability such as poor contact.

Therefore, there is a strong demand for an induction heating coil having a low loss and high efficiency even with a multilayer structure, and having a reduced size.

Japanese Patent Laid-Open No. 2001-210460

An object of the present invention is to provide an induction heating coil that has low loss and high efficiency, is small in size, and has a simple structure.

The present inventor has paid attention to using an electric wire in which a plurality of conductors are arranged in parallel to form a composite conductor, and has solved the above-mentioned problems all at once.

According to the inventor of the present invention, an electric wire in which an insulator is collectively covered around an outer periphery of a composite conductor arranged in parallel with a plurality of adjacent conductors in contact with each other is wound in an annular shape. A coil is provided.

The following effects can be expected from the induction heating coil of the present invention.
(A) Since the bare conductors that are not covered with the insulator are arranged in parallel to form a composite conductor, the effective cross-sectional area of the conductor portion can be increased, so that the loss is reduced and the efficiency is increased.
(B) Since the insulator is collectively covered with the composite conductor in which a plurality of bare conductors not covered with the insulator are arranged in parallel, the outer dimensions of the coil can be reduced.
(C) Since there is no need to peel off the insulator and bond a plurality of strands at both ends of the strand (conductor) as in the prior art, a coupler is not required and the configuration is simplified and the number of man-hours is reduced. Become.
(D) Since the adjacent conductors are arranged in parallel in contact with each other over the entire length of the coil, the problem of poor contact does not occur, so that reliability is improved.
(E) There is no need to use a conductor having a special shape, and a conductor generally used for electric wires can be used. Therefore, it is highly available and can be provided at a low price.

It is a top view which shows an example of the coil for induction heating which concerns on this invention. It is AA sectional drawing of FIG. It is a top view which shows an example of the conventional induction heating coil. It is AA sectional drawing of FIG.

Hereinafter, an aspect of the present invention will be described with reference to FIGS. 1 and 2 with respect to an induction heating coil in which a composite conductor including two conductors is wound in an annular shape.
In the figure, 1 is a coil for induction heating, 2 is an electric wire in which two conductors 2a are made into a composite conductor, 2b is an insulator coated on the outer periphery of the composite conductor 2a, and 3 is an electric wire 2 fixed in an annular shape. 4 is a binding tape for fixing the outer periphery of the electric wire 2.

A feature of the present invention is that a composite conductor arranged in parallel with two adjacent conductors in contact with each other is used, and the insulator is collectively covered.
By doing this, the wire (conductor) is not covered with an extra insulator as in the conventional case, so the effective conductor part per coil cross-sectional area increases, and as a result, the coil inductance and impedance can be reduced. Thus, the loss is reduced and the heating efficiency is increased.
Furthermore, since the insulator is simply covered on the composite conductor in which a plurality of bare conductors not covered with the insulator are arranged in parallel, the outer dimensions of the coil can be reduced.

Hereinafter, a more detailed description will be given based on FIGS. 1 and 2.
As shown in the sectional view of FIG. 2, the induction heating coil of the present invention is arranged in parallel with two adjacent conductors 2a in contact with each other to form a composite conductor. And the electric wire 2 with which the insulator 2b was coat | covered collectively is used for the outer periphery of this composite conductor, and this is wound by planar shape on the base material 3 which consists of a double-sided tape. Here, in order to generate a higher magnetic field, it is necessary to increase the number of turns (number of turns) of the coil as much as possible.
Therefore, in the induction heating coil of the present invention, the arrangement direction of the composite conductors arranged in parallel is in a ring shape on the base material 3 made of double-sided tape so that the direction of winding is perpendicular to the winding direction, that is, the thickness direction of the coil. It is wound. And in order to make fixation of the electric wire 2 more firm, as shown in FIG. 1, it fixes with the binding tape which consists of fixing tapes at four places of the outer periphery of the electric wire bundle.

The conductor 2a used in the present invention may be a metal used for a normal electric wire such as copper or a copper alloy such as a copper silver alloy wire. Regarding the strands constituting the conductor, in consideration of the skin effect or winding property due to high frequency, a conductor in which a plurality of strands are twisted instead of a single wire is desirable. What is necessary is just to select suitably according to the strength of the magnetic field to generate | occur | produce also about a conductor diameter.
Next, the insulator 2b may be a material having excellent heat resistance, and various resins such as a fluororesin, a polyethylene resin, and a polyolefin resin can be selected.
Moreover, about the base material 3, it is comprised from the member which consists of a double-sided adhesive tape with an acrylic adhesive, a metal foil tape with an adhesive, a heat-resistant resin tape, etc. The thickness of the substrate is preferably in the range of 0.1 mm to 0.3 mm in consideration of strength and thickness dimensions.
Further, the binding tape 4 is not particularly required, and a normal adhesive tape, metal foil tape, heat resistant resin tape, polyester tape, etc. can be used. The thickness is preferably in the range of about 0.03 mm to 0.05 mm.

Next, a method for manufacturing the induction heating coil of the present invention will be described.
First, the manufacturing method of the long electric wire which consists of a composite conductor is demonstrated first.
What is necessary is just to use the dice | dies and two-apple which are used by manufacture of the electric wire by well-known extrusion molding, and arrange | positions two long conductors 2a in parallel in the mutually contact state, and forms a composite conductor.
Then, the insulator 2b may be collectively covered with an extruder (not shown) on the outer periphery of the composite conductor. Next, the long electric wire obtained by the above manufacturing method is cut into a predetermined length, and this is wound and fixed, but the direction in which the arrangement direction of the parallel arranged composite conductors is orthogonal to the winding direction, that is, Wind and fix so that it is in the thickness direction of the coil. By doing so, the circumferential width of the coil is the same as in the prior art, so the number of turns is the same as in the prior art. On the other hand, since the cross-sectional area of the conductor portion is twice that of the conventional method shown in FIGS. 3 and 4, the impedance is lowered and the current capacity is also doubled, so that the generated magnetic field can be increased.
And if the fixing tape 4 is wound around the outer periphery four places of the wire bundle finally wound and fixed, and it fixes on the base material 3, the coil for induction heating of this invention will be obtained.

In the above description, description of connection members such as connectors and connectors connected to both ends of the coil is omitted, but various connection members can be connected.
The winding shape is also an annular shape, but in addition to this, an optimal shape may be selected according to the specification application such as a spiral shape, an elliptical shape, a rectangular shape, or the like.
As described above, in the present invention, a composite conductor in which a plurality of conductors are coupled inside is used. Therefore, the insulator is peeled off at both ends of a conventional wire (conductor) and a plurality of elements are separated. Since it is not necessary to connect the wires, a coupler is not required, the configuration is simplified, and the number of man-hours is greatly reduced.
Further, since it is not necessary to further twist the strands as in the case of conventional litz wires, man-hours are reduced in this respect as well.
Furthermore, since the conductors adjacent to each other along the entire length of the coil are fixed by the insulator in a state of being arranged in parallel in contact, there is no fear of causing a problem of contact failure, so that reliability is improved.
Finally, in the above description, an example of a composite conductor in which two conductors are arranged in parallel as a composite conductor has been shown. However, it goes without saying that the composite conductor can be developed into a composite conductor having three or more parallel arrangements in a row. Furthermore, it should be noted that, within the scope of the present invention, the present invention can be applied to composite conductors arranged in parallel in close contact with a polygonal shape such as a triangular shape or a quadrangular shape without being limited to a line shape.

Embodiments of the present invention will be described based on examples.

[Example 1]
Two long conductors 2 each having a length of 100 m obtained by concentrically twisting 19 strands made of copper having a strand diameter of 0.18 mm were prepared.

Next, the above two conductors are arranged in parallel to an extruder to which dies and two tuples are attached.

Next, a fluororesin is coated by extrusion from the extruder as an insulator 3 on the conductors arranged in parallel.
Thus, a composite conductor electric wire having an outer shape of 2.0 mm in width and 1.1 mm in height was obtained. At this time, the thickness of the insulator was set to 0.1 mm.

The long electric wire created above is cut into 5 m, and the conductor is arranged in an annular shape in such a direction that the arrangement direction of the conductors is perpendicular to the annular plane, in other words, the height of the electric wire is in the width direction of the coil. The winding and four places of the coil were fixed with the binding tape 4. At this time, the inner diameter of the ring was 126 mm, the width of the ring was 12.1 mm, and the number of turns was 11 turns.
Finally, the coil fixed in an annular shape is fixed on the base material 3 made of double-sided tape, whereby the induction heating coil of the present invention is obtained.

The induction heating coil thus obtained was subjected to a performance comparison with a conventional coil by applying a predetermined voltage across the coil.

[Comparative Example 1]
The conductor diameter of one conductor is the same as in the embodiment, and a coil formed by extrusion coating an insulating layer having the same insulator type and thickness as the embodiment on the outer periphery of one conductor is as shown in FIGS. The structure was stacked on the layers.

As a result, it was confirmed that the induction heating coil of the present invention generates a magnetic field almost twice that of the induction heating coil of the comparative example.

The induction heating coil of the present invention is not limited to an IH rice cooker, and can be similarly applied to an electromagnetic cooker, an induction heating fixing device of a copying machine, or other induction heating devices.

1 Induction heating coil 2 Electric wire 2a Conductor (composite conductor)
2b Insulator
3 Base material (double-sided tape)
4 Binding tape

Claims (3)

An induction heating coil obtained by winding a wire in which an insulator is collectively covered around an outer periphery of a composite conductor arranged in parallel with a plurality of adjacent conductors in contact with each other. 2. The induction heating coil according to claim 1, wherein the plurality of conductors are arranged in parallel in a row, and the row direction of the conductors of the electric wire is wound in a direction perpendicular to the plane. . The induction heating coil according to claim 1 or 2, wherein the flat surface has an annular shape.

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