Heater wires and planar heaters

Abstract

To provide a heater wire that can be readily disposed while keeping its heat resistance and voltage endurance even when an installation space is narrowed due to miniaturization of an object to be heated, and provide a planer heater in which the heater wire is disposed.SOLUTION: A heater wire has insulation cover layers formed on a heating member, where at least one of the insulation cover layers is a braid structure composed of a plurality of insulation filaments and at least part of a space between the insulation filaments of the braid structure is filled with an insulation material. It is preferable that the braid structure is placed in the outermost layer of the insulation cover layers, and the thickness of the insulation material except the insulation cover layer is less than 200 μm.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention is applicable to heating wires used for heating and heat preservation of household electric appliances such as electric rice cookers and electric carpets, and heating wires and planar heaters provided with heating wires, such as vehicle seat sheets and toilet seats.

Background Art

[0002] Recently, with the progress of miniaturization of the appliance body in which the planar heater is incorporated, the area for arranging the planar heater has been significantly narrowed. Due to the narrowing, the heating wire is arranged in the planar heater in a denser state than before, and thus tends to become locally hot. Therefore, the requirement for heat resistance of the heating wire is increasing more and more.

[0003] Patent Document 1 describes an electric heater (heating wire) provided with a coating layer formed by braiding inorganic or organic fibers on a heating wire (resistance wire), and further provided with a resin coating layer made of synthetic resin thereon. In addition, it is described that the resin coating layer uses a fluororesin.

[0004] When the fluororesin is used as the resin coating layer in the electric heater of Patent Document 1, it has excellent heat resistance. However, since it is applied to the upper layer in which the fibers are braided, if a fluororesin layer with a thickness of 200 μm is applied as in the example, the outer diameter of the heating wire increases and becomes hard, and there is a problem that it is difficult to arrange the heating wires densely.

[0005] In addition, a structure in which a silicone varnish is applied as the resin coating layer with a structure similar to that of Patent Document 1 is generally known. However, the resin coating layer made of silicone varnish is likely to crack when the bending radius R becomes small in the arrangement in a narrow part, and the deterioration of the withstand voltage is significant. Therefore, it is not suitable for the arrangement in a narrow part.

[0006] Therefore, there is an urgent need to develop a heating wire that is excellent in flexibility and is easy to arrange even when the arrangement space of the heating wire is narrowed due to the miniaturization of the appliance body (hereinafter referred to as the heated body) while maintaining the heat resistance and withstand voltage of the heating wire.

[0007] [Patent Document 1] Japanese Patent Publication No. 2010-97809 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide a heater wire with excellent flexibility that is easy to install even when the space for installing the heater wire is reduced due to the miniaturization of the object to be heated, while maintaining heat resistance and voltage resistance, and a planar heater on which the heater wire is installed. [Means for solving the problem]

[0009] The gist of the heater wire and planar heater of the present invention is as follows.

[0010] (1) A heater wire having one or more insulating coating layers formed on a heating element, wherein at least one layer of the insulating coating layer is a braided structure made up of multiple insulating wires, and an insulating material is filled in at least a portion of the space between the insulating wires of the braided structure. (2) The braided structure is preferably formed in the outermost layer of the insulating coating layer. (3) The thickness of the insulating material excluding the insulating coating layer is preferably less than 200 μm. (4) The insulating material is preferably made of polytetrafluoroethylene. (5) The insulating coating layers, excluding the outermost layer, are preferably a horizontally wound structure consisting of multiple insulating linear bodies, and there are four or more layers. (6) It is preferable that the insulation breakdown voltage of the heater wire does not change before and after the three turns with R=5. [Effects of the Invention]

[0011] The heater wire and planar heater of the present invention can be expected to have the following excellent effects. (1) Unlike conventional technology, this structure fills the spaces between the linear members of the braided structure with insulating material, allowing the thickness of the insulating material to be reduced. This maintains heat resistance and voltage resistance while allowing for a smaller diameter and improved flexibility. (2) As a result of its excellent flexibility, it can be installed densely, and can be adapted even when the heated object is further reduced in size. (3) Even when installed in narrow spaces with tight bending radii, cracks on the heater surface can be prevented, resulting in excellent voltage resistance. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example of the heater wire of the present invention. [Figure 2] This figure shows another example of the heater wire of the present invention. [Figure 3] This figure shows an example of a planar heater using the heater wire of the present invention. [Figure 4] A schematic diagram illustrating the flexibility testing method according to the present invention is shown. [Modes for carrying out the invention]

[0013] An example of the heater wire of the present invention will be described below with reference to the drawings.

[0014] In Figure 1, the heater wire 1 has a heating element 4 in which a resistance wire 3 is wound around a core material 2, an insulating coating layer 6 made of a braided structure applied to it, and at least a portion of the space between the wires in the insulating coating layer 6 is filled with an insulating material 7.

[0015] The present invention relates to a heater wire 1 having one or more insulating coating layers 6 formed on a heating element 4, characterized in that at least one layer of the insulating coating layer 6 is a braided structure made up of a plurality of insulating wires, and an insulating material 7 is filled in at least a portion of the space between the insulating wires.

[0016] As a feature of the present invention, at least one layer of the insulating coating layer is a braided structure. Also, the number of layers of the insulating coating layer is not particularly limited. As shown in FIG. 1, it may consist of a single layer of the braided structure, or as in the insulating coating layers 5 and 6 of FIG. 2, a plurality of layers may be provided. The structure of the insulating coating layer is made of insulating linear bodies, and in addition to the braided structure, it may be a horizontally wound structure and is not particularly limited. The horizontally wound structure is excellent in productivity compared to the braided structure. The braided structure has the characteristic of being less likely to come apart compared to the horizontally wound structure. For the purpose of preventing loosening, it is preferable that the outermost insulating coating layer 6 is a braided structure.

[0017] From the viewpoints of insulation and heat resistance, the most preferable structure is one in which a plurality of layers of an insulating coating layer 5 made of a horizontally wound structure are provided on the heating member, and further an insulating coating layer 6 made of a braided structure is provided on the outermost layer, and then the spaces between the wires of the insulating coating layer 6 are filled with an insulating material 7. From the viewpoint of improving insulation, it is preferable that the insulating coating layer consists of 4 or more layers. Further, in view of productivity, it is preferable that the inner insulating coating layer excluding the outermost layer consists of a horizontally wound structure.

[0018] As a further feature, at least a part of the spaces between the linear bodies of the braided structure of the outermost insulating coating layer 6 is filled with an insulating material 7. The insulating material 7 only needs to be filled in at least a part of the spaces between the linear bodies, and preferably it is preferably filled over the entire surface of the heater wire 1 so that there are no gaps. During the terminal processing by the heater cut machine, the insulating linear bodies do not come apart and the terminal processability is improved.

[0019] Since the insulating material 7 is filled in the spaces between the linear bodies of the braided structure, it is applied substantially in the same layer as the insulating coating layer 6. Therefore, it is preferable that the outer diameter of the heater wire 1 hardly changes before and after filling the insulating material 7, but it may be thinly applied to the upper layer of the insulating coating layer 6 as long as the flexibility is not impaired, and it is not particularly limited.

[0020] When the insulating material 7 is applied up to the upper layer of the insulating coating layer 6, the thickness of the insulating material 7 excluding the insulating coating layer 6 (that is, the thickness of the insulating material 7 applied to the upper layer of the insulating coating layer 6) is preferably less than 200 μm, more preferably less than 100 μm, still more preferably less than 70 μm. From the viewpoint of improving flexibility by reducing the diameter, it is most preferably less than 50 μm.

[0021] The insulating material 仅需施加在由编织结构体构成的最外层绝缘被覆层6上即可,但也可以填充到内侧的绝缘被覆层5中,没有特别限制。从防止松散(终端加工性)的角度来看,绝缘材料7填充到最外层以下的绝缘被覆层的线状体内之间是优选的,更优选的是,填充到所有的绝缘被覆层中。

[0022] The material of the insulating linear bodies constituting the insulating coating layers 5 and 6 is not particularly limited, and examples thereof include inorganic fibers such as glass fibers and ceramic fibers, or organic fibers such as aramid fibers. From the viewpoints of heat resistance, durability, and versatility, glass fibers are preferred. The configuration of the braided structure or the horizontally wound structure is not particularly limited.

[0023] The material of the insulating material 7 is not particularly limited, but it is preferably a fluororesin, and among them, polytetrafluoroethylene (PTFE) is most preferred from the viewpoints of heat resistance and diameter reduction.

[0024] The manufacturing method of the insulating material 7 is not particularly limited, but in order to uniformly fill between the insulating coating layers made of linear bodies, a method of impregnating a heater wire with an aqueous dispersion (dispersion) of the insulating material 7 and fixing it is preferred. From the viewpoints of the formability and appearance of the step of filling between the wires of the insulating coating layer 6, the viscosity (23 °C) of the aqueous dispersion is preferably 10 to 100 mPa·s. More preferably, it is 10 to 50 mPa·s. The lower the viscosity, the easier it is to fill to the inside of the insulating coating layer, so it is more preferred from the viewpoint of preventing loosening. Also, it is preferred in terms of being able to reduce the wall thickness compared to extrusion coating.

[0025] Furthermore, the present invention is designed so that the dielectric breakdown voltage does not change before and after three turns with a radius of R=5. Due to its excellent resistance to bending, insulation is maintained and stable use is possible even when installed in narrow areas with tight bending radii. Here, "does not change" means that there is no change that exceeds the measurement error (variation).

[0026] The basic structure of heater wire 1 is shown below, but is not limited to this.

[0027] The structure of the heating element 4 is not particularly limited, but from the viewpoint of flexibility, a structure in which a resistance wire 3 is wrapped around a core material 2 is preferred.

[0028] The material of core material 2 is not particularly limited, but glass fiber, polyamide fiber, polyester fiber, rubber elastic core, etc. can be used, and among these, a material made by twisting multiple glass fibers together (glass core) is particularly preferred.

[0029] For the resistance wire 3, nickel-chromium wire, copper-nickel wire, iron-chromium wire, etc., can be appropriately selected and used. The dimensions (diameter) of the resistance wire should be determined appropriately according to the required amount of heat, with those of φ0.02 to φ0.26 being particularly suitable.

[0030] Figure 3 shows an example of a planar heater 8 on which the heater wire 1 of the present invention is arranged. The planar heater 8 is designed to a desired shape according to the specifications of the object to be heated, and the heater wire 1 is arranged and fixed within its surface. As the size of the object to be heated decreases, the space for arranging the heater wire 1 becomes increasingly narrow, but the present invention has excellent flexibility, allowing for dense arrangement. Furthermore, because it has excellent heat resistance, even if the heater wire 1 becomes locally hot during use due to the dense arrangement, there is no risk of damage or deterioration of the heater wire 1.

[0031] The structure of the planar heater 8 is not particularly limited. For example, a heater wire 1 is arranged and fixed to the surface of a double-sided adhesive member (not shown) of a desired shape corresponding to the specifications of the object to be heated, and a heat conductive member 9 is further attached to the surface of the double-sided adhesive member so as to cover the heater wire 1. The heat conductive member 9 is not particularly limited, and any metal commonly used as a heat conductive material, such as aluminum or copper, may be used, but aluminum foil is preferred for its versatility. Both ends of the heater wire 1 are connected to lead wires 11 via connectors 10. [Examples]

[0032] The following describes an embodiment of the heater wire 1 of the present invention.

[0033] The heater wire in Example 1 uses a structure in which a resistance wire 3 with a diameter of φ0.04 to 0.12, made of copper-nickel wire or nickel-chromium wire, is wound around a core material 2 made of glass core, as the heating element 4. Three layers of horizontally wound structures made of glass fiber bundles are applied as insulating coating layers on the heating element 4, and then a braided structure of the same material is applied. Furthermore, an insulating material made of PTFE is filled so as to cover the entire surface of the insulating coating layers. The insulating material is filled between the linear bodies of all the insulating coating layers, and the thickness of the insulating material excluding the insulating coating layers is approximately 25 μm.

[0034] The heater wire in Example 2 will have four layers of the horizontal winding structure as in Example 1.

[0035] The heater wire in Example 3 will have five layers of the horizontal winding structure as in Example 1.

[0036] The heater wire in Example 4 will have six layers of the horizontal winding structure as in Example 1.

[0037] The heater wire in Comparative Example 1 is the same as in Example 2, but with only an insulating coating layer and no insulating material applied. The outer diameter is φ2.4.

[0038] The heater wire in Comparative Example 2 is the same as in Example 2, but with silicone varnish applied as the insulating material. The thickness of the insulating material, excluding the insulating coating layer, is approximately 75 μm.

[0039] Processability evaluations, dielectric strength tests, and flexibility tests were performed on the examples and comparative examples, and the results are shown in Table 1. The details of each test method are as follows.

[0040] (Processability evaluation) When cutting the heater wire, check for any fraying of the insulating wire at the end. If no fraying occurs, the workability is considered good.

[0041] (Withstand Voltage Test Method) The dielectric breakdown voltage (kV) will be checked for any change before and after winding the heater wire three times around the mandrel (R=5). The dielectric breakdown voltage test method will be based on JIS C 2110, with an applied voltage of 2000V and a duration of 2S.

[0042] (Flexibility test) A 25g weight is attached to a 500mm long heater wire 10mm from the end, and the wire is fixed so that 250mm extends beyond the pivot point of the measuring stand. Measure the distance X (mm) between the measuring stand and the heater wire. (See Figure 4)

[0043] [Table 1]

[0044] The heater wires of Examples 1 to 4 have insulating material filled between the insulating linear bodies of the braided structure, and since PTFE is used as the insulating material, they have excellent heat resistance and can be applied thinly to 25 μm. Compared to the comparative example, they have been shown to be smaller in diameter and have improved flexibility. As a result, their durability against bending is improved, and they have excellent stability without deterioration of voltage resistance even when bent. This makes it possible to arrange heater wires with a small bending radius even in narrow spaces. Furthermore, the processability of the heater wire ends is also excellent, as no fraying occurs.

[0045] Comparative Example 1, lacking an insulating material, experienced fraying during processing of the heater wire ends. In Comparative Example 2, when a silicone varnish was applied to the insulating material, no fraying occurred and the processability was good. However, cracking of the silicone varnish occurred when bending to R=5, resulting in a deterioration of the withstand voltage test.

[0046] Based on the above, the heater wire of the present invention maintains heat resistance and voltage resistance while exhibiting excellent flexibility, making it suitable for installation in confined spaces.

[0047] The above examples are merely examples of heater wires and planar heaters of the present invention, and it goes without saying that various modifications and applications are possible within the scope of the concept of the present invention. [Industrial applicability]

[0048] This is merely one example of the heater wire and planar heater of the present invention, and it goes without saying that various modifications and applications are possible within the scope of the concept of the present invention. It is particularly suitable as a heater for the lid of small home appliances such as rice cookers, but it can be applied to various other uses. [Explanation of Symbols]

[0049] 1 Heater wire 2 Core material 3 Resistance wire 4. Heat-generating components 5. Insulating coating layer (horizontal winding structure) 6. Insulating coating layer (braided structure) 7. Insulating materials 8-sided heater 9. Heat conductive material 10 connectors 11 Lead wires

Claims

1. In a heater wire in which multiple insulating coating layers are formed on a heating element, The aforementioned insulating coating layer consists of insulating wires, At least one layer of the insulating coating layer is a braided structure consisting of a plurality of insulating linear bodies, The braided structure is formed in the outermost layer of the insulating coating layer, At least a portion of the space between the insulating linear members of the braided structure is filled with insulating material. The insulating material is filled from the outermost layer down to the spaces between the linear elements of the insulating coating layer below, The heater wire is characterized in that the insulating material is made of polytetrafluoroethylene.

2. The heater wire according to claim 1, characterized in that the insulating material is filled between all the linear bodies of the insulating coating layer.

3. The insulating coating layer, excluding the outermost layer, is a horizontally wound structure consisting of multiple insulating linear bodies, and is characterized by being applied in four or more layers. A heater wire according to either claim 1 or 2.

4. The heater wire according to any one of Claims 1 to 3, characterized in that the thickness of the insulating material excluding the insulating coating layer is less than 200 μm, and the viscosity of the insulating material is 10 to 100 mPa·s.

5. The method is characterized by ensuring that the dielectric breakdown voltage does not change before and after three turns with a radius of R=5 mm. A heater wire according to any one of claims 1 to 4.

6. A planar heater having heater wires according to any one of claims 1 to 5.

7. A planar heater according to claim 6, for use in household electrical appliances.

Images