JPS61269882A - Surface heat generating body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a sheet heating element used in heating equipment, cooking equipment, drying equipment, health equipment, anti-freezing equipment, etc. that utilize electrical energy.

BACKGROUND OF THE INVENTION Conventionally, this type of sheet heating element has been constructed as shown in FIG. 7a.
A steel plate 21 for hollow holes is coated with an insulating hollow hole 22, and a thin metal electric resistance heating element (
Hereinafter referred to as a heating element) 2 is formed with an embedded coating,
When the heating element 2 is energized, the insulation hollow 22 → the steel plate for hollow hollow 2
1→Heat was conducted through the insulating poro 22, heating the entire surface and generating heat in a planar manner (for example, in Japanese Patent Laid-Open No. 58
-225592, Japanese Utility Model Application No. 57-171296, Japanese Utility Model Application No. 59-294).

Furthermore, as shown in FIG. 7, a metal thin heating element 2 is installed between the heat-resistant glasses 23 and 24 and fixed. Some have a coated structure, and when the heating element 2 is energized, heat is conducted to the heat-resistant glass, heating the entire surface and generating heat in a sheet shape.More generally, the heating element is fixed between two sheets of synthetic mica. There are some covered ones.

Problems to be Solved by the Invention However, the above structure, that is, the insulating hollow hole 2
In the planar heating element in which the heating element 2 is embedded and coated in step 2, the heating rate of the heating element 2 is faster than that of the insulating hollow hole 22 when electricity is applied, so the expansion of the heating element 2 is larger than that of the insulating hollow hole 22. Fine cracks are generated at the interface between the insulating hollow 22 and the heating element 2, which tends to cause deterioration of electrical properties, that is, insulation resistance and dielectric strength. If the finer racks further expand, peeling will occur at the interface between the insulating hollow 22 and the heating element 2, and there is a high possibility that the peeled part of the heating element 2 will be abnormally heated and disconnected. On the other hand, for a planar heating element in which the heating element is fixedly covered with two sheets of heat-resistant glass, the mechanical strength can be improved by increasing the thickness of the heat-resistant glass 23, 24, but the heat conduction is slow and the heating rate is slow. .

Furthermore, since it is made of glass, it has low mechanical strength and cannot be made into a large shape.

The present invention solves these conventional problems and aims to improve electrical properties (insulation resistance, dielectric strength), heating properties (temperature increase rate), mechanical strength, and life properties.

Means for Solving the Problems In order to solve the above problems, the planar heating element of the present invention has a thin metal heating element fixedly coated between two hollow substrates having excellent electrical insulation properties. It is a planar heating element consisting of the following structure.

For production The effect of this technical means is as follows.

In other words, a hollow substrate with excellent electrical insulation is made by applying a glaze that has excellent adhesion to the fabric and has excellent insulation properties to a steel plate fabric for hollow metal (hereinafter referred to as fabric) that has been pretreated using a general method. The material is glazed (sprayed, dipped, or electrodeposited), dried, and fired to create an insulating hollow substrate. The method for forming the insulating hollow includes: (1) 1 coat 1 bake;
A single insulating hollow layer or a multi-layer hollow layer such as 2 coats 1 bake, ■, 2 coats 2 bake, ■, 3 coats 3 bakes etc. are acceptable.In particular, a hollow layer with excellent insulation is essential for the surface layer that fixes and covers the heating element. The thickness is preferably at least 100 μm or more. ■ Hollow board consists of two types: main functional parts and auxiliary parts.The main functional part, that is, the hollow board that requires value-added functions, is called hollow board A, and the auxiliary part, that is, the hollow board that fixes and covers the heating element, is hollow. If substrate B is used, hollow substrate A is larger than hollow substrate B in terms of the thickness and shape of the fabric and hollow substrate. That is, it is important that the hollow substrate B is configured to have a smaller heat capacity than the hollow substrate A.

What is more important is that the hollow substrate deforms during heating and the space between hollow substrate A and hollow substrate B increases due to the deformation.
In order to solve the problem that the bonding area of the three parts becomes small, the heating element in the part where it is not bonded becomes abnormally heated, and there is a possibility of wire breakage. As shown in the example, the hollow substrates A and B are provided with reinforcing structures (metal spots, beads, etc.), the hollow substrates A and B are each provided with fixed positioning fitting parts, and a heating element is provided in the fitting parts. It is necessary to have a structure in which a part of the adhesive is tightly fixed, that is, the adhesive area is increased.

Further, as shown in FIG. 5, by bending the hollow substrate A so that at least the terminal extraction portion of the heating element and the corresponding end surface of the hollow substrate B do not come into direct contact, the heating element and the hollow substrate B are connected. It is also necessary to improve the dielectric strength of the material. This is because the edges of the fabric are press-processed, so burrs occur on the edges, and it is basically difficult to coat the hollow layer, and when electricity is applied, the hollow substrate B leaks.
Easy to cause insulation failure. For this reason, the end face of the hollow board is made as long as possible from the heating element terminal extraction part, and the shape is such that the required insulating hollow layer can be secured, that is, the bending process is performed on 2RB, and at least A bend of 90 degrees or more is required.

As described above, two types of hollow substrates with excellent insulation properties, hollow substrate A and hollow substrate B, are created, a thin metal heating element is installed on the surface of hollow substrate A, and the heating element is replaced with hollow substrate B. A sheet heating element with a fixed coating can solve the problems of the prior art. That is, (1) the heating element does not peel off from the insulating hollow layer and the wire does not break.

■ As for the energization method, for products with a buried coating formed, the applied voltage is gradually increased in stages to reduce the occurrence of cracks. It disappears.

■ Use at higher temperatures (the softening point of the hollow surface is usually MAX5)
00°C), the electrical characteristics and life characteristics can be significantly improved.

(2) Even when used at high temperatures (surface temperature of 300°C or higher), there is no need for the installation method with equipment, that is, a double insulation structure, and an inexpensive configuration is possible.

■ Compared to the case of using heat-resistant glass, various steel plates can be used as the material, so it can be used as an insulating hollow substrate, with large shapes,
It can be formed into any shape (flat, corrugated, spherical, etc.), has significantly improved mechanical strength, does not break, and can be made thinner than heat-resistant glass, so it can be heated at a faster rate. can.

Example 1 Using the configuration shown in FIG. 1, the hollow substrate A1 had a material board thickness of 1. (Lmm, fabric A consisting of copper plate for bow o with dimensions 150 mm square, and hollow substrate B are fabric board thickness 0-8 mm,
Dough B consisting of a steel plate for enameling with dimensions of 130 mm square was subjected to the usual pretreatment for enamelled material, and then sprayed and glazed with the undercoat enameled composition shown in Table 1 A, so that the undercoat enameled film thickness after firing was 100 to 120 ttm. Then, the surface of the undercoat hollow was spray-glazed with the insulating hollow composition shown in Table 1 B, and after firing, the total film thickness of the undercoating hollow and the insulating hollow was 3.
Hollow substrates A1 and B3 were created so that the thickness was 00±20 μm.

The heating element 2 is a stainless steel (SUS430) steel plate with a thickness of 1
Using 00 μm, etching it into the shape shown in Figure 8, the outer dimension is 100 mm square, and when 100 V is applied, 5
The electric resistance heating element 2 (hereinafter referred to as heating element) is made of a thin metal plate so as to obtain a power of 00 W.

As a planar heating element, as shown in FIG. 9, the heating element 3 is installed between the hollow substrate A1 and the hollow substrate B3 on the refractory brick 8, and the support 4 is installed at the corner of the hollow substrate B3.
There are 6 stainless steel load sets made of books, and the total load is 4KJ.
The hollow substrate A1, the heating element 3,
A hollow substrate B3 was fixedly coated. To measure the surface temperature of the planar heating element below, use an ordinary surface thermometer, and use the hollow substrate A.
The center part M is measured.

Next, as a comparison sample, a planar heating element formed with an embedded coating was made of the same plate thickness and shape as the fabric A, and was composed of an undercoating hollow A and an insulating hollow B, with a total film thickness of 400 ± 20 μm, and an insulating hollow layer. The heating element is buried and coated at a position 100 μm from the surface (a loading platform is installed). On the other hand, the planar heating element using heat-resistant glass has a glass plate thickness of 3.0 m.
The shape of the hollow substrates A and B was the same as that of the hollow substrates A and B, and the substrates were fixed and coated by the method shown in FIG.

The temperature rise curve and life characteristics were confirmed by the methods shown in Table 1 and Table 2. The results are shown in FIGS. 10 and 11. 1st
Figure 0 shows the temperature rise curve, and Figure 11 shows the electrical characteristics (insulation resistance).

Table 2 and Table 3 show that 200. The appearance of a dropped steel ball and the electrical properties after 100 cycles under the life cycle conditions shown in Table 2 are shown.

As is clear from Tables 3 and above, Figures 10, 11, and 3, the product of the present invention has: ■ The temperature rise characteristics of the product of the present invention are better than that of the buried type B as shown in Figure 10. A is slightly slower (about 1 minute), but the maximum temperature is the same. However, the heat-resistant glass type C is extremely slow, and the maximum temperature is about 20°C lower than that of the product of the present invention.

In other words, the ranking is B) A)) C.

■ As shown in Figure 11, product A of the present invention has an excellent life characteristic of 100 MΩ or more even after 1000 cycles, while the buried type B has a significantly deteriorated insulation resistance of 0.5 MΩ after 1000 cycles. It is. On the other hand, in the case of heat-resistant glass C, it is excellent in that it is 100 MQ or more even after 1000 cycles, similar to product A of the present invention, but the vicinity of the heating element becomes opaque, causing deterioration in appearance. That is, A>C
) will be ranked B.

■ In terms of mechanical strength and electrical properties, product A of the present invention has good mechanical strength and no deterioration in insulation resistance even after mechanical shock, but buried type B has some hollow cracks due to mechanical shock. Because parts of the heating elements and heating elements were exposed, the insulation resistance deteriorated significantly, and the exposed parts in particular were unusable due to disconnection. Furthermore, the heat-resistant glass type was destroyed by mechanical shock, and its characteristics could not be confirmed.

The ranking will be A>>B>C.

It can be seen that the products of the present invention are superior to the conventional products in the overall evaluation of electrical properties, temperature rise properties, mechanical strength, and life properties.

Example 2 As shown in FIGS. 2 and 3, a hollow substrate A (IA or IB), a heating element 2, and a hollow substrate B (3A or 3B) are connected.
) was forcibly fitted and fixed, and the hollow processing, heating element, and fixing method were the same as in Example 1. however,
Enameled steel plate A, fabrics A and B, which are the openings, have a diameter of 20 mm and a height of 5 at the position shown on the outer peripheral edge of the heating element 2, respectively.
A conical fitting portion 12 of mm 2 was provided. In particular, in this example, the results are shown in FIG. 12 for the purpose of improving the temperature rise characteristics and deformation. As is clear from the figure, the time required to reach the maximum temperature could be reduced by about 30%. Further, due to the fitting portion 12, there is no misalignment of the heating element 2 and the hollow substrate B (3A or 3B), and almost no deformation occurs.

Embodiment 3 FIG. 4 shows a third embodiment of the present invention, in which a hollow substrate A (IC) having the same shape as that of Embodiment 2, a heating element 2, and a hollow substrate B (
3C), the thickness of fabric B is 1.0, 0.8, 0.
．． 6 and 0.4 mm, and the hollowing and fixed coating methods were the same as in Example 1, and the results of the temperature rise characteristics are shown in Table 4. As is clear from Table 4, by making the heat capacity of the fixed coating hollow substrate B as smaller as possible than that of the hollow substrate A, the temperature increase characteristics were significantly improved.

Table 4 Example 4 Examples 1 to 3 were all based on a dedicated fixing coating method, but in FIG.
, shows an example of a method of fixing and covering hollow substrate B (3F). That is, a screw fastener IF' is spot welded to the hollow substrate AIF, and the fixing fitting 5 is pressed with the screw 4, thereby fixing the hollow substrate AIF and the hollow substrate B3F. The main functional surface of the hollow substrate A does not have any attached parts, and this method can be said to be preferable in terms of appearance. Although not shown, the structure (fixed coating method) of the planar heating element is basically a three-layer structure of hollow substrate A - heating element - hollow substrate B, and a screw tightening method,
There are also spring methods.

Example 5 The configuration shown in FIG. 13, that is, a rectangular hollow substrate AlG
1 Heating element 2, hollow board B3G is fixed with four screws 9 through washers 11 and nuts 10, and aluminum foil 13 is fixed on the surface of hollow board B3G with the four screws. The plate thickness of fabric B of Example 4 shown in
．． It was constructed from a hollow substrate B (3G) using 4mm. Table 5 shows the temperature rise characteristics, and as is clear from the table, by providing aluminum foil, the hollow substrate B
The heat dissipated from 3G was reduced, and it was possible to obtain a temperature increase characteristic close to that of the buried type planar heating element of Comparison (2).

Table 5 Example 6 As shown in FIG.
Table 6 shows the electrical properties of the dielectric strength, which was bent at 90 degrees or more with respect to IE), and the hollowing and fixed coating methods were the same as in Example 1.

As is clear from Table 6, by bending the end surface of the hollow substrate B, when electricity is applied, the heating element 2 is connected to the hollow substrate B.
leakage prevention can be significantly improved. In addition, in order to secure an insulating hollow layer, at least 2 bending processes are required.
RJ2 is required.

Furthermore, although it is preferable to bend the entire end face of the hollow substrate B, if necessary, only the terminal extraction portion of the heating element may be partially bent.

Effects of the Invention As described above, the planar heating element of the present invention provides the following effects.

- Since the hollow substrates A and B can be processed individually, the defect rate of hollow processing is low, and a low-cost planar heating element can be produced.

■ Because the heating element can be fixedly covered, the heating element can be in any shape, such as plate, band, or line.More importantly, in the case of the buried type, the coefficient of linear expansion with the hollow hole, the plate thickness, etc. However, in the present invention, the material and shape can be arbitrarily selected according to the usage conditions.

(2) As with item 0 above, since all are single parts, they are inexpensive as planar heating elements.

■ Since it is a hollow substrate, the electrical properties, mechanical strength, life properties, and temperature rise properties can be significantly improved.

■ Since it is a hollow substrate, its temperature rise characteristics and mechanical strength can be significantly improved compared to heat-resistant glass.

(2) By providing the joint part of the hollow substrate K1, the heating element can be fixed, the hollow substrates A and B can be fixed, and the deformation and temperature rise characteristics can be significantly improved.

■ Even if the heating element is disconnected or the hollow board is damaged, it can be easily replaced because it is a single component.

■ Since it is a hollow substrate, it can be applied to large-sized objects.

- By attaching a foil such as aluminum to the hollow substrate B, the temperature rise characteristics are improved, and the heating on the foil side is significantly reduced, making it easy to take measures against heat when attaching the foil to a device.

[Brief explanation of the drawing]

FIG. 1 is a basic sectional view of a planar heating element in a first embodiment of the present invention, FIGS. 2 and 3 are enlarged sectional views of essential parts of a planar heating element in a second embodiment of the invention, and FIG. Figure 4 shows the third aspect of the present invention.
5a and 5b are enlarged sectional views of essential parts of the sheet heating element in the sixth embodiment of the present invention, and FIG. 6 is a cross-sectional view of the sheet heating element in the fourth embodiment of the present invention. FIGS. 7a and 7b are enlarged sectional views of the main parts of a conventional planar heating element, and FIG. 8 is a plan view of the heating element used in each embodiment of the present invention. , FIG. 9 is a cross-sectional view showing a dedicated fixing method for covering a sheet heating element used in each embodiment of the present invention, and FIG.
The figure is a temperature rise characteristic diagram in the first embodiment, FIG. 11 is an electrical characteristic diagram in the first embodiment, FIG. 12 is a temperature rise characteristic diagram in the second embodiment, and FIG. 13 is a main part in the fifth embodiment. FIG. 3 is an enlarged exploded cross-sectional view. 1...Hollow board A, 2...Heating element,
3...Hollow board B0 Name of agent: Patent attorney Toshi Nakao (man) and 1 other person! 1
．． Ho〇Hasaka A Figure 1 2. ... t, air resistance @ body 3 ... Holo cardinal number B /A ... Ho 0 shame @A Fig. 3 3C-= -0 curtain uLS Fig. 5 fD, E, , store -0 Shyness A 21. (B4C, E... Holo board B 2... Plaster spoon anti-Yaku body Fig. 7 (Q) Fig. 8 Fig. 9 Fig. 10 Time to release (Intermediate Fig. 11) Cycle song ('ciil) Fig. 12 P accent 1 yo 閏 (intermediate) Fig. 13

Claims (5)

[Claims] (1) A planar heating element in which an electrical resistance heating element is installed on the surface of an electrically insulating hollow substrate A, and the electrical resistance heating element is fixedly covered with an electrically insulating hollow substrate B. (2) A planar heating element according to claim 1, wherein a fixed positioning fitting part is provided on each of the hollow substrate A and the hollow substrate B, and a part of the electric resistance heating element is closely fixed to the fitting part. body. (3) Claim 1, in which the heat capacity of the hollow substrate A and the hollow substrate B is smaller than that of the hollow substrate A.
The planar heating element according to item 1 or 2. (4) At least the end surface of the hollow substrate B corresponding to the terminal extraction part of the electric resistance heating element is 90 degrees with respect to the hollow substrate A.
The planar heating element according to claim 1, 2, or 3, which is formed by bending the heating element more than 100 degrees. (5) A planar heating element according to claim 1, 2, 3, or 4, wherein an aluminum foil is attached as a heat reflecting plate to the exterior surface of the hollow substrate B.