JP2010062080A - Planar heating element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar heating element superior in thermal efficiency, reliability, and maintainability by a simple constitution. <P>SOLUTION: In the planar heating element 10 having the heating element 1 and a heating plate 2 to pinch the heating element 1 via a coating layer 3, the coating layer 3 is formed on respective faces of the heating plate opposed to the heating element out of thickness directions of the heating plate by silicon nitride or ceramic material containing alumina, and a groove part 4 to house a linear or a foil-like heating element 1 is formed in the coating layer 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a planar heating element in which a heating element is sandwiched between heating plates having an insulating layer.

  Conventionally, planar heating elements used for processing industrial products, etc., as represented by so-called mica heaters, sandwich a metal heating element formed into a wire or foil shape between mica (mica) plates and pressurize it. Insulation is performed through processing steps such as bonding and bonding, and a metal plate or the like that is a heating plate is sandwiched. Some use silicon rubber or fluororesin sheets instead of mica plates. This flat heater is sandwiched between metal plates, which are mainly heating plates, and is widely used as a planar heating element.

  FIG. 3 is a side sectional view of a conventional planar heating element. FIG. 4 is a side sectional view showing a configuration of a conventional planar heating element. The conventional planar heating element 20 includes a flat heater 23 in which a heating element 21 such as a metal is sandwiched between mica plates 22 and a heating plate 24 in which both surfaces of the flat heater 23 are sandwiched.

  In Patent Document 1, a heat diffusion layer is formed by applying a binder in which an inorganic adhesive is added to ceramics such as aluminum nitride to a metal heating element, and this is layered between inorganic insulators such as mica and heated. A flat heating element is disclosed which is pressed and integrated.

JP-A-6-283257

  However, in the above prior art, among the insulators sandwiching the heating element under the condition of continuously using the planar heating element, the heat resistance is limited to about 150 ° C. for resin and rubber and about 300 ° C. for mica plate, The request for continuous use at higher temperatures could not be met. Further, in the configuration as in the above prior art, it is necessary to always prepare a flat heater as shown in FIG. 2 as a spare for repair such as replacement when the heating element is disconnected. Moreover, in the technique of patent document 1, since silicon is used for the inorganic adhesive, siloxane acid may be generated to cause a contact failure or the like.

  In view of the above problems, an object of the present invention is to provide a planar heating element having a simple configuration and excellent thermal efficiency, reliability, and maintainability.

In order to solve the above problems, the present invention is characterized by the following.
The invention according to claim 1 is a planar heating element having a heating element and a heating plate sandwiched through the heating element via an insulating layer, wherein the insulating layer is the heating element in the thickness direction of the heating plate. It is formed on each surface of the heating plate facing the body, and a groove for accommodating the heating element is formed in the insulating layer.

  According to a second aspect of the present invention, in the planar heating element, the insulating layer includes a ceramic material containing silicon nitride or alumina.

  According to a third aspect of the present invention, in the planar heating element, the insulating layer includes a heat resistant resin.

  According to the present invention, a coating layer having insulating properties such as ceramics is formed on the heating plate, and the coating layer and the heating element are separated from each other, so that the thermal efficiency and reliability are excellent with a simple configuration. A planar heating element is provided.

  Furthermore, if the heating element breaks down due to disconnection or the like, it is possible to replace only the heating element without replacing the insulating layer and the heating element as in the prior art, so that maintenance is easy and the maintenance cost is reduced. it can.

  Furthermore, by providing the groove in the insulating layer, the heating element can be easily positioned in the manufacturing process.

  The best mode for carrying out the present invention will be described below with reference to the drawings. The following description is an example of the best mode of the present invention, and it is easy for a person skilled in the art to make other embodiments within the scope of the claims by making changes and modifications within the scope of the claims. However, this does not limit the scope of the claims.

  FIG. 1 is a side sectional view showing a planar heating element according to an embodiment of the present invention. FIG. 2 is a side sectional view showing the configuration of the planar heating element. The planar heating element 10 includes a heating element 1, a heating plate 2 that sandwiches the heating element 1 from both sides, and a coating layer formed on each surface of the heating plate that faces the heating element 1 in the thickness direction of the heating plate. 3.

  The heating element 1 is made of a heat-resistant metal heating element having a high resistivity such as nickel chrome or iron chrome, and is formed in a linear or foil shape having a desired resistance value.

  The heating plate 2 is not particularly limited as long as it can transfer the heat generated by the heating element 1 to the object to be heated, but is preferably heat resistant and has a flat surface.

  Specifically, the heating plate 2 uses a metal plate such as an aluminum plate, a stainless plate, or a copper plate. A ceramic plate such as a low expansion glass plate, a crystallized glass plate, an alumina plate, or a silicon nitride plate may be used. However, since the ceramic plate is generally an insulator, there is an advantage that it is not necessary to dispose an insulating material. However, heat conductivity is inferior to that of metal plates and thermal efficiency is inferior.

  Since the metal plate has good heat conductivity but is conductive, in use, it is necessary to form an insulating layer as the coating layer 3 shown in FIG. 2 between the heating element 1 and the heating plate 2. Conventionally, a flat heater 23 in which an insulator such as a heating element 11 and a mica plate 22 shown in FIG. 4 is integrated has been used. However, as described above, insulators such as the mica plate 22 are inferior in thermal efficiency and maintainability. Therefore, in the present invention, the coating layer 3 is formed on the heating plate 2 to ensure insulation between the heating plate 2 and the heating element 1.

  The coating layer 3 is formed by spraying a ceramic material on the surface facing the heating element 1 in the thickness direction of the metal plate that is the heating plate 2. In the present embodiment, the two heating plates 2 sandwich the heating element 1. Accordingly, the coating layer 3 is formed on each surface of the two heating plates 2 facing the heating element 1. For spraying the coating layer 3, plasma spraying or gas spraying is preferably used. As the ceramic material, silicon nitride, alumina, or the like is suitably used as a high-temperature structural material that has insulating properties and is used under severe conditions at high temperatures. A heat resistant resin may be used instead of the ceramic material. When the coating layer 3 is formed of a heat resistant resin, the resin is sprayed on the heating plate 2 and baked. For example, there is Teflon (registered trademark) as a heat resistant resin. However, although the heat resistant resin is superior to the ceramic material in terms of cost, the heat resistant resin is inferior to the ceramic material in heat resistance. Therefore, the heat resistant resin is used according to the usage form of the planar heating element 10. That is, a ceramic material may be used if the planar heating element 10 has a high temperature specification, and a heat resistant resin may be used if the specification is low.

  Besides thermal spraying, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), sol-gel method, etc. may be used.

  For example, when a ceramic material is used, the thickness of the coating layer 3 may be about 200 μm under the condition of alternating current of 200 volts, as long as electrical insulation between the heating element 1 and the heating plate 2 can be secured. Good. When the heat-resistant resin is used, the coating layer 3 can be made denser and thinner than when a ceramic material is used.

  Next, when the heating element 1 is sandwiched between the heating plates 2 having the coating layer 3, a groove or the like is processed in the coating layer 3 in accordance with the shape of the heating element 1 so that stress and restraining force are not applied to the heating element 1. It is necessary to apply. This is because the heating element 1 has a thickness regardless of whether it is linear or foil, and this thickness is accommodated in the coating layer 3.

Specifically, the groove 4 is formed by performing the following process.
First, a groove matching the shape of the heating element is formed with a tool such as an end mill during machining of the heating plate 2. Considering that the coating layer 3 will be formed later, the width and depth of the groove formed in the heating plate 2 are set to be larger dimensions. After that, when the coating layer 3 is formed on the heating plate 2 having the groove shape by the above-described thermal spraying or the like with a ceramic material or a heat resistant resin, the coating layer 3 having the groove portion 4 is formed. The coating layer 3 having the groove 4 may be formed on one of the two heating plates 2 or on both of the heating plates 2. In FIG. 2, the groove 4 is formed in the coating layer 3 of one heating plate 2.

  The heating element 1 having a coating layer 3 having a groove 4 corresponding to the shape of the heating element 1 is sandwiched from both sides with a heating plate 2 and is fastened with screws or the like, whereby a planar heating element 10 according to an embodiment of the present invention is formed. Is produced.

  As described above, since it is possible to omit the lamination of the conventional heat insulating material using mica, the heat of the heating element 1 can be efficiently transmitted to the heating plate 2. For this reason, since the temperature of the heating element 1 can be set lower than the conventional one, the life of the heating element 1 can be extended.

  Further, when the heating element 1 is damaged due to disconnection or the like, maintenance is facilitated because only the heating element 1 needs to be replaced.

  Furthermore, by providing the groove 4 in the insulating layer, the heating element can be easily positioned in the manufacturing process.

  Furthermore, since the ceramic material has a heat resistance of about 1500 ° C., when the ceramic material is used for the coating layer 3, when the heating element 1 is made of a metal, the resistance to dielectric breakdown is increased as compared with the conventional mica.

It is a sectional side view which shows the structure of the planar heating element which becomes one Embodiment of this invention. It is a sectional side view of the planar heating element which becomes one Embodiment of this invention. It is a sectional side view which shows the structure of the conventional planar heating element. It is a sectional side view of the conventional planar heating element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating body 2 Heating plate 3 Coating layer 4 Groove part 10 Planar heating element 21 Heating element 22 Mica 23 Flat heater 24 Heating plate 20 Planar heating element

Claims (3)

In a planar heating element having a heating element and a heating plate that sandwiches the heating element via an insulating layer,
The insulating layer is formed on each surface of the heating plate facing the heating element in the thickness direction of the heating plate, and
A planar heating element characterized in that a groove for accommodating the heating element is formed in the insulating layer. The planar heating element according to claim 1,
The planar heating element, wherein the insulating layer includes a ceramic material containing silicon nitride or alumina. The planar heating element according to claim 1,
The insulating layer includes a heat resistant resin.
A planar heating element characterized by that.

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