JPH07114977A - Sheet heating element - Google Patents

Abstract

(57) [Summary] [Purpose] The present invention is intended to obtain a planar heating element having a uniform temperature distribution and excellent durability. [Structure] In a planar heating element having a metal foil heating element 1 in which a heating element circuit 1-2 is formed on a metal foil 1-1, the metal foil heating element 1 includes a metal foil 1-1 and a heating element circuit 1-2. To form a predetermined resistance value by alternately arranging a zone A having a constant length in the vertical direction and a zone B having a constant length in the horizontal direction to form a predetermined resistance value. The heat diffusion part 1-3 is formed by connecting only one end to the heating element circuit 1-2 in the gap between the U-turn parts of 1-2, and the metal foil heating element 1 is sandwiched with the electrically insulating material 2 to be formed integrally. A planar heating element with a simplified structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet heating element used in electric cookers, electric heaters and the like.

[0002]

2. Description of the Related Art Conventionally, as an example of a planar heating element in which a heating element pattern is formed on a metal foil by etching, etc.
No. 9-20012, a meandering heating element pattern is provided in a fixed direction to improve the manufacturing method, and two circuits are formed in the same shape to improve resistance as shown in Japanese Patent Publication No. 52-2734. As disclosed in Japanese Patent Application Laid-Open No. 1-211884, it is considered that a pattern is formed in a rectangular spiral shape to improve the temperature distribution in the central portion.

[0003]

The conventional sheet heating element has been considered with respect to the manufacturing method and the temperature distribution regarding the pattern. However, when it is used at a high temperature of about 300 ° C., the sheet heating element is deformed by thermal stress. However, the temperature distribution characteristics change, for example, in the planar heating element used by sandwiching it with a glass ceramic plate or the like, the planar heating element is deformed by thermal stress, and therefore the planar heating element is separated from the glass ceramic plate surface, There is a drawback in that the temperature distribution changes greatly and a partial temperature rise causes a serious problem in durability.

The present invention is intended to provide a planar heating element which is not deformed by thermal stress due to thermal expansion even at a high temperature of about 300 ° C.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is a planar heating element having a metal foil heating element in which a heating element circuit is formed on a metal foil. In this case, a zone A in which a heating element circuit is patterned in a certain length in the vertical direction on a metal foil and a zone B in which a heating element circuit is patterned in a certain length in the horizontal direction are alternately arranged to obtain a predetermined resistance value. Form a heat diffusion part by connecting only one end to the heating element circuit in the gap of the U-turn part of the heating element circuit of the metal foil, and further form the metal foil heating element by sandwiching it with an electrically insulating material to form an integral body. It has been transformed.

[0006]

Since the sheet heating element of the present invention is constructed as described above, the zone A in which the heating element circuit of the metal foil is patterned to have a constant length in the vertical direction and the zone A having a constant length in the horizontal direction are formed. When the metal foil heating element in which the thermal diffusion portion is formed by connecting only one end to the heating element circuit having the predetermined resistance value by alternately arranging the changed zone B, the vertical zone A is heated in the vertical direction. The zone B in the lateral direction expands and thermally expands in the lateral direction with different 90 ° orientations, and the thermal expansion due to heat generation is smaller than that of the heating element circuit having a pattern configured in only one direction. The heat diffusion portion improves heat conduction to make the surface temperature uniform, and the electrically insulating material integrated by sandwiching the metal foil heating element electrically insulates the metal foil heating element and reduces thermal deformation of the metal foil heating element.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an external perspective view of a sheet heating element to which an embodiment of the present invention is applied, FIG. 2 is a sectional plan view of an essential portion of the sheet heating element, and FIG. 3 is an enlarged plan view of the sheet heating element. is there.

In the figure, reference numeral 1 denotes a metal foil heating element, which is a metal foil 1-1, a heating element circuit 1-2, and a heat diffusion section 1-which will be described later.
3 and lead wire portions 1-4. Metal foil 1-
1 is made of a material such as nickel-chromium, iron-chromium, etc., which has excellent heat resistance and high resistivity, and has a thickness of 5
It is about 0 to 100 μm. Reference numeral 1-2 is a heating element circuit, which is used to process the metal foil 1-1 by a method such as etching, pressing or electric discharge machining so that a predetermined shape and resistance value can be obtained. The maximum length of the length L of the heating element circuit 1-2 is 10
It is 0 mm or less, for example, 50 mm. The zones A and B are subdivided into a zone A in which the heating element circuits 1-2 are arranged in a vertical direction and are patterned, and a zone B in which the heating element circuits 1-2 are arranged in a horizontal direction and are arranged in a horizontal direction and are patterned. The metal foil heating elements 1 are formed by alternately arranging them to have a predetermined resistance value.
Reference numeral 1-3 is a heat diffusion portion formed of a metal foil piece provided by connecting only one end to the heating element circuit 1-2. A gap between the heating element circuits 1-2, for example, a U-turn portion of the heating element circuit 1-2, causes a gap and deteriorates the temperature distribution. In order to fill, the heat diffusion part 1-3 is provided with one end of the heat generation circuit 1-2 with a width of 1/10 of the heat generation circuit 1-2. The heat diffusion part 1-3 is provided. Since it is connected only at one end, it conducts heat but does not conduct electricity and does not generate heat. Reference numeral 1-4 is a lead wire portion, which has a cross-sectional area which is 2-3 times larger than that of the heating element circuit 1-2, and connects between the heating element circuits 1-2 in the metal foil heating element 1.

Reference numeral 2 is a sheet-like electric insulating material which is excellent in heat resistance and electric insulation and is made of, for example, mica laminated.
The thickness of the laminated mica is about 0.1 to 0.4 mm.
The sheet heating element 3 is formed by sandwiching the metal foil heating element 1 between the electrically insulating materials 2 and heat-molding them to integrate them. Reference numeral 4 is a plate made of glass ceramics, and the sheet heating element 3 is sandwiched between two plates 4 and the ends thereof are fixed by a heat resistant adhesive 5 made of silicone rubber or the like. The heat resistant temperature of the plate 4 is as high as 600 ° C, and the coefficient of thermal expansion (α) is -2 x 1
Withstands rapid heating and quenching as low as 0 to ⁷ / ℃, and has a thermal conductivity (λ) of 1.
3 kcal / m. hr. It is as small as ℃ and its heat conduction is low.

Next, the operation of this embodiment will be described.

When the plate 4 is heated by the sheet heating element 3 and an object to be heated is placed on the plate 4, the temperature of the plate 4 is temporarily lowered, but the sheet-like electric insulating material 2 is provided below the plate 4. The sandwiched metal foil heating element 1 is joined and integrated to form a planar heating element 3, and further, the metal foil heating element 1
Since the heat diffusion section 1-3 is provided inside the heat generating circuit 1-2, the heat conduction is improved, the thermal response is good, and the heat is quickly transmitted to the plate 4, and the heat generating circuit 1-2 is connected between the heat generating circuit 1-2. The temperature distribution is good and the temperature is good, and the heat can be evenly transferred to the object to be heated so that it can be heated in a short time without temperature unevenness.

In the sheet heating element 3, the thermal expansion zone of the metal foil heating element 1 is finely divided into blocks as described above, and the thermal expansion directions are different. A thermally expands in the vertical direction, and zone B in the horizontal direction expands in the horizontal direction with different 90 ° orientations, and the thermal expansion due to heat generation is less than that in the case where the strip-shaped heating element is provided only in one direction. The thermal expansion generated in the entire planar heating element 3 is small, as a result, the thermal stress is small, the thermal deformation is small, and it can be used even at a high temperature of about 300 ° C. Further, the block of the metal foil heating element 1 has a predetermined resistance value, and the planar heating element 3 can be easily designed only by arranging the blocks.

Further, since the planar heating element 3 is sandwiched and fixed between the two plates 4 made of glass ceramics, there is no thermal deformation and abnormal heating due to peeling or the like does not occur, thereby greatly improving durability. Further, the surface of the plate 4 is flat and has excellent cleanability, and if the oil film is baked with salad oil or the like before use, the cleanability tends to be further improved.

[0014]

As described above, according to the present invention, in the metal foil heating element, the heating element circuit is patterned on the metal foil in the vertical direction to have a constant length and in the horizontal direction to have a constant length. Since the zone B and the zone B are alternately arranged, there is no deformation due to thermal expansion of the heating element, there is an effect in terms of temperature distribution, temperature rise, durability, etc., and the U-turn portion of the heating element circuit of the metal foil is effective. Since only one end is connected to the heating element circuit in the gap to form the heat diffusion part, the heat conduction between the heating element circuits is good and the temperature distribution is uniform, and the metal foil heating element is sandwiched with an electrically insulating material. It is molded and integrated to further suppress thermal expansion, reduce thermal deformation, maintain adhesion, and maintain good heat conduction.
There is an effect that a sheet heating element excellent in terms of temperature distribution, temperature rise, durability, etc. can be provided.

Further, since the resistance value of the divided metal foil heating element block is fixed, the resistance value of the sheet heating element can be easily designed.

[Brief description of drawings]

FIG. 1 is an external perspective view of a planar heating element according to an embodiment of the present invention.

FIG. 2 is a plan cross-sectional view of a main part of the planar heating element.

FIG. 3 is an enlarged plan view of the relevant part.

[Explanation of symbols]

 1 Metal Foil Heater 1-1 Metal Foil 1-2 Heater Circuit 1-3 Heat Diffuser 2 Electrical Insulation Material

Claims (1)

[Claims] 1. A metal foil (1-1) is provided with a heating element circuit (1-
In a planar heating element having a metal foil heating element (1) formed with (2), the metal foil heating element (1) includes a metal foil (1-
In FIG. 1), a zone A in which the heating element circuit (1-2) is patterned to have a constant length in the vertical direction and a zone B in which the heating circuit (1-2) is patterned to have a constant length in the horizontal direction are alternately arranged to have a predetermined resistance. Value, and further, this heating element circuit (1
-2) is connected to the heating element circuit (1-2) only at one end in the gap of the U-turn section to form a heat diffusion section (1-3), and the metal foil heating element (1) is connected to an electrically insulating material ( A planar heating element characterized in that it is formed by sandwiching it in 2) to be integrated.