JP2012048972A - Coil wire and coil for induction heating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil wire for induction heating and a coil for induction heating which can be fixed on a coil holding member and which can hold a coil shape even in an 200°C environment.SOLUTION: A coil wire for induction heating has an insulation layer made of fluorine resin formed by extrusion coating on a conductor wire, has a fusion layer made of polyester resin formed by extrusion coating on the insulation layer, and has the fusion point of the fluorine resin to configure the insulation layer higher than the fusion point of the polyester resin to configure the fusion layer. A coil for induction heating is fused to be integrated with the coil wire by melting and solidifying the fusion layer of the coil wire, while the coil wire is wound around spirally or cylindrically.

Description

The present invention relates to a coil wire for induction heating and a coil for induction heating that can be suitably used as, for example, a coil for a heating cooker or the like using an electromagnetic induction heating method.

  In recent years, heating cookers using an electromagnetic induction heating method have become widespread in ordinary households. As such a coil wire for an induction heating cooker, for example, a plurality of conductor wires on which an insulating film is formed are bundled to form an assembly wire, and the assembly wire is twisted to form a conductor wire, and an insulating layer is formed on the conductor wire. It is known that various fusion layers are formed on this insulating layer. As the insulating layer, it is necessary to have excellent heat resistance that can withstand a high temperature environment such as a cooking device, and therefore, a fluororesin is mainly used. Moreover, in recent induction heating cookers for home use, a high frequency of 40 to 100 kHz is passed through the coil wire in order to cope with copper pans and aluminum pans with low permeability, and thus corona resistance is required. From this point, a fluororesin having a low dielectric constant is preferably used. Such a coil wire is wound in a spiral shape to form a high-power coil. At this time, in order to stabilize the shape of the coil, the fused layer is melted and solidified to be integrated with each other. (For example, refer to Patent Documents 1 to 4).

JP 2010-135157 A: Hitachi AP Japanese Patent No. 3601533: Matsushita Electric Industrial Co., Ltd. Japanese Patent No. 4096712: Matsushita Electric Industrial Co., Ltd. JP 2000-58251 A: Crabe

  Due to the recent demand for higher output, it is necessary to improve the heating efficiency of the coil, and as the amount of heat generation increases, it is also necessary to improve the heat resistance of the coil. Here, the coil wire according to Patent Document 1 is configured by winding a PPS (polyphenylene sulfide) tape with a fusion layer. In the case of such tape winding, a step or a gap (interval where no tape is present) is inevitably generated, so that a portion that cannot be fused is generated, and the fusion cannot be firmly integrated. Thereby, the shape of the coil wound in a spiral shape collapses, and the heating efficiency may deteriorate. Further, the coil wires according to Patent Documents 2 and 3 are made of a fluororesin having a low melting point in the fusion layer. The coil is installed in a heating cooker after being held by the coil holding member. However, since fluororesin is a material that is difficult to adhere, the coil is held by an adhesive in the case of coil wires according to Patent Documents 2 and 3. It cannot be held on the member. Therefore, although it hold | maintains at a coil holding member by a fixing member and screwing etc., work efficiency will deteriorate while the number of parts increases. In addition, if the coil and the coil holding member are not completely fixed due to variations in work when the coil is held by the coil holding member, the coil will be misaligned, resulting in deterioration of heating efficiency and noise due to vibration. It will be. Further, in the coil wire according to Patent Document 4, the fusion layer is made of any one of a polyester elastomer, a polyamide resin, and a polyurethane resin. As described above, the amount of heat generation has increased due to the recent increase in output, and the coil wire is also exposed to a high temperature of about 200 ° C. Since all of the above materials have a melting point of 200 ° C. or lower, when applied to a heating cooker with high output, the fused layer is melted during heating. Thereby, while the shape of the coil wound by the spiral shape will collapse | crumble, the melted heat-fusion layer will flow and will contaminate the inside or periphery of a heating cooker.

  The present invention has been made to solve the above-described drawbacks of the prior art. The object of the present invention is to ensure the holding to the coil holding member and even in an environment of about 200 ° C. An object of the present invention is to provide a coil wire for induction heating and a coil for induction heating that can maintain the coil shape.

In order to achieve the above object, the coil wire for induction heating according to claim 1 of the present invention is such that an insulating layer made of a fluororesin is formed on a conductor wire by extrusion coating, and a fusion layer made of a polyester resin on the insulating layer. Is formed by extrusion coating, and the melting point of the fluororesin constituting the insulating layer is higher than the melting point of the polyester resin constituting the fusion layer.
In the coil wire according to claim 2, the polyester resin constituting the fusion layer is polybutylene terephthalate.
In addition, in the induction heating coil according to claim 3, in the state where the coil wire is wound in a spiral shape or a cylindrical shape, the fused layer of the coil wire is melted and solidified so that the coil wires are fused. It is an integrated piece.

  According to the present invention, by using a polyester resin having a high melting point as the fusion layer, the fusion layer does not melt even in an environment of about 200 ° C., and the coil shape can be maintained. Further, since the polyester resin is a material having high adhesiveness, it can be fixed to the coil holding member with an adhesive, and can be reliably and easily held. Further, since the polyester resin is a hard material, the position of the coil wire can be prevented from moving after the fusion integration.

It is the figure which showed the Example of this invention, and is a partially notched perspective view which shows the structure of the coil wire for induction heating. It is the figure which showed the Example of this invention, and is a perspective view which shows the structure of the coil for induction heating.

  Hereinafter, with reference to FIG. 1, the coil wire 10 which concerns on embodiment of this invention is demonstrated. Polyester amide-polyimide amide insulation coating is formed on an annealed copper wire with an outer diameter of 0.05 mm to form a conductor strand, 30 conductor strands are S-twisted to form an assembly wire, and then 40 assembly wires are Z-twisted. Thus, a conductor wire 1 having a diameter of 2.5 mmφ was obtained. The outer periphery of the conductor wire 1 was coated with a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) by extrusion molding to form an insulating layer 2 having a thickness of 0.25 mm. The melting point of this PFA is 310 ° C. Polybutylene terephthalate (PBT) was coated on the outer periphery of the insulating layer 2 by extrusion to form a fusion layer 3 having a thickness of 0.2 mm. The melting point of this PBT is 225 ° C.

  The coil wire 10 thus obtained is wound in a spiral shape or a cylindrical shape as shown in FIG. 2, and then the fusion layer 3 is melted and solidified so that the coil wires 10 are fused together. By integrating, the induction heating coil 20 is obtained. Such an induction heating coil 20 is held on a coil holding member by an adhesive, and connection terminals are connected to both ends of the coil wire 10 by a method such as fusing connection, and is installed in an induction heating cooker or the like. Will be.

  The present invention is not limited to the above embodiment. The conductor wire 1 may be any conductor wire that is normally used as a coil, and the configuration of the conductor wire may be appropriately set according to the purpose. As for the insulating film formed on the conductor wire, a conventionally known material may be appropriately selected. In some cases, the insulating film may not be formed. When the conductor wire is twisted to form the conductor wire 1, the twist pitch and twist direction may be set as appropriate, and multi-stage twisting such as further twisting the twisted wire may be repeated. Moreover, the form of the wire assembly is not limited to the concentric circle form, but may be an ellipse, a sector, or a flat form.

  The material constituting the insulating layer 2 is a fluororesin. For example, tetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer ( ETFE) and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Any of these fluororesins may be used, but in consideration of heat resistance, it is preferable to use PTFE or PFA having a high melting point, and among these, PFA that can be extruded is used. It is preferable to do.

  Polyester resin is used as the material constituting the fusion layer 3. For example, polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate. Aromatic polyester resins such as (PBN). In general, many resin materials having a high melting point are hard, and if such a hard material is used as a fusion layer, the coil wire 10 becomes inflexible. When such a coil wire 10 is formed in a spiral shape or a cylindrical shape, not only a large force is required for bending, but also a crack is generated in the fusion layer. On the other hand, when a flexible material such as polyester elastomer is used, when an external force is applied in a process of holding the dielectric heating coil 20 on the coil holding member or the elasticity of the conductor wire 1 and the insulating layer 2 ( There is a possibility that the coil wire 10 is displaced due to the restoring force. Since the polyester resin as described above has a high melting point of 200 ° C. or higher and has an appropriate hardness, the flexibility of the coil wire 10 is maintained, and the coil wire 10 Misalignment can be prevented. Among the polyester resins, it is particularly preferable to use PBT that is particularly hard and has excellent moldability. In addition, PBT is a grade that has various properties enhanced by blending, etc., but in the present invention, an adhesive improvement grade is selected in order to strengthen the adhesion between coil wires, or an environment where a thermal cycle is applied. Therefore, it is preferable to select a heat shock resistant grade.

  The melting point of the fluororesin constituting the insulating layer 2 needs to be higher than the melting point of the polyester resin constituting the fusion layer 3. This prevents the insulating layer 2 from being melted by the heat of extrusion molding when the fusion layer 3 is extrusion coated on the insulating layer 2, and provides insulation when the fusion layer 3 is melted and solidified. This is to prevent the layer 2 from melting.

  In the present invention, the insulated wire having the above configuration is wound in a spiral shape or a cylindrical shape, and then the insulated wire is fused and integrated to form an induction heating coil. Any conventionally known method can be employed as means for fusing and integrating the insulated wires, and is not particularly limited. For example, a method in which an insulated wire wound in a spiral shape or a cylindrical shape is left in a tank maintained at a predetermined temperature for a predetermined time and integrated by heat fusion, or a predetermined current is passed through the conductor of the insulated wire For example, there may be mentioned a method in which the fusion layer is heated and melted from the inside by resistance heat generated thereby to integrate.

  The dielectric heating coil 20 obtained as in the above embodiment was subjected to a heat resistance test. The dielectric heating coil 20 was energized to increase the temperature, and the temperature of the coil surface was maintained at 200 ° C. for 1 hour, and then the surface condition, positional deviation of the coil wire 10 and the like were confirmed. In the dielectric heating coil 20 according to the present embodiment, even after the heat resistance test, the surface state did not change, and the positional deviation of the coil wire 10 did not occur.

  Moreover, although the induction heating coil 20 was held on the coil holding member by a commercially available adhesive, it was confirmed that the induction heating coil 20 was held by a sufficient adhesive force.

  The coil wire and the induction heating coil according to the present invention can be reliably held on the coil holding member and can maintain the coil shape even in an environment of about 200 ° C. Therefore, for example, it can be suitably used for an induction heating cooker, an electric rice cooker, an electric kettle, etc., in which a pan is placed on the top plate and heated.

DESCRIPTION OF SYMBOLS 1 Conductor wire 2 Insulating layer 3 Fusion layer 10 Coil wire 20 Dielectric heating coil

Claims (3)

An insulating layer made of fluororesin is formed by extrusion coating on the conductor wire, and a fusion layer made of polyester resin is formed by extrusion coating on the insulating layer, and the melting point of the fluororesin constituting the insulating layer is A coil wire for induction heating having a melting point higher than that of the polyester resin constituting the fusion layer. The coil wire for induction heating according to claim 1, wherein the polyester resin constituting the fusion layer is polybutylene terephthalate. 3. Induction in which the coil wire is wound into a spiral shape or a cylindrical shape, and the fused layer of the coil wire is melted and solidified so that the coil wires are fused and integrated. Coil for heating.

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