JPS6114156Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in planar heating elements, particularly to increases in current carrying capacity.

Conventionally, there are various types of sheet heating elements depending on their uses, but the present invention is a current-carrying electrode suitable for use in long lengths, such as insulating and heating large tanks and pipes, and melting snow on roads and roofs. The present invention provides a planar heating element with a large band current carrying capacity.

In general, a sheet heating element is made up of a sheet conductor having an electric resistance suitable for heat generation, and a plurality of band-shaped current-carrying electrode strips for carrying electricity. Metal foil tapes made of aluminum, braided wires, conductive paints such as silver paint are known in the form of strips, and metal wires woven or sewn into them. Easily energized is about several A (amperes) per electrode, and the length is about 1 to 2 tatami mats, i.e. about 1 m to 3 m, such as electric carpets, electric heating mats, electric tatami mats, and electric floor panels. Although it can be used without problems up to a few hundred watts, it can also be wrapped around large tanks or pipes, or placed inside roads or under tin plates on roofs for the purpose of melting snow or preventing freezing. In order to minimize the non-heat generating area at seams and to simplify electrical wiring work by minimizing the number of electrical connection points, sheet heating elements are used in a range of several meters to
A long cable with a large electrical capacity of more than 10 meters and several hundred watts to several thousand watts is required, but conventional ones have the problem of insufficient electrical capacity of the current-carrying electrode band near the feeder line. Ta.

As a countermeasure for this problem, it is possible to increase the electrical resistance of the current-carrying electrode band, that is, to increase the cross-sectional area of the current-carrying electrode band, that is, to increase the thickness or width of the current-carrying electrode band. However, if the thickness is increased, the flexibility as a planar heating element will decrease, and the undulating deformation will become difficult to recover, so that when installing the current-carrying electrode band, the thickness of the current-carrying electrode band and its waving deformation will be reduced. There are problems such as gaps forming and impairing heat conduction, so the thickness needs to be as thin as possible. On the other hand, if the width is widened, the area under the electrode generates almost no heat, so the non-heat generating area becomes wider.
In particular, when snow melting is used for roofs that are installed perpendicular to the slope of the eaves, the snow does not melt in the non-heat generating areas, leaving a bank-like ice and snow zone there and forming a pool-like water pool. There are problems such as the formation of clumps and icicles, so it is necessary that the width of the current-carrying electrode band be as narrow as possible.

In other words, a planar heating element is required to have contradictory functions such as having a thin and narrow current-carrying electrode band and a large current-carrying electric capacity.

The present invention was arrived at as a result of intensive research in view of the above situation.A planar conductor is formed between base materials that also serve as electrical insulators, and the planar conductor is placed on both sides or between both sides in the width direction. Or in a planar heating element in which a current-carrying electrode band is provided within a planar conductor,
The current-carrying electrode strips provided on both sides in the width direction are laminated with a planar conductor through an electrically insulating layer on their inner sides, and the current-carrying electrode strips provided in the middle in the width direction are electrically connected on both sides. This is a planar heating element characterized by being laminated with a planar conductor through an insulating layer.

To explain this invention in more detail using drawings,
FIG. 1 is a cross-sectional view of an example of a sheet heating element according to the present invention, in which a sheet conductor 2 is placed on a base material 1 which also serves as an electric insulator, and current-carrying electrode bands 3 are provided near both ends of the sheet conductor 2. It is being This current-carrying electrode band 3 is laminated with the planar conductor 2 via the electric insulating layer 4 on one side in the width direction, that is, on the inner side. Electrical contact with the conductor 2 is prevented. However, the other side in the width direction, that is, the portion near the outside, is in contact with the planar conductor 2.

In addition, an electrical insulator 5 is placed on top of these as necessary.
may be provided.

FIG. 2 is a cross-sectional view of an example of a planar heating element according to the present invention, similar to FIG. There is a planar conductor 2 between base materials 1 and 5 which also serve as electrical insulators, and current-carrying electrode bands 3 are embedded in portions near both ends of the conductor. This current-carrying electrode band 3 also has a structure in which one side in the width direction, that is, the inner part, is laminated with the planar conductive band 2 via the electrical insulating layer 4, so that the current-carrying electrode band 3 and the planar conductor Electrical contact with 2 is blocked on the inside,
The other side in the width direction, that is, the portion near the outer end surface is in contact with the planar conductor 2 .

Here, the base materials 1 and 5 that also serve as electrical insulators are not directly related to the present invention, but are generally used as base materials for electrical insulation of the planar conductor 2 and for forming it. Specific examples include plastic films, sheets, and cloth impregnated with electrically insulating resin.

The planar conductor 2 may be one obtained by coating, drying and curing a conductive paint made of conductive carbon powder, metal powder, etc. on the base material 1, a conductive paint impregnated into a fabric, or a base material. 1 has metal plated and vacuum-deposited, which corresponds to the one shown in Figure 1. There is also a sheet-like material made by kneading the above-mentioned conductive powder into rubber or plastic stick, which corresponds to the planar conductor shown in FIG. In any case, a normal planar conductor can be used.

Next, as the current-carrying electrode band 3, a metal foil tape made of copper, aluminum, nickel, etc. having a thickness of several microns to about 100 microns and a width of several mm or more, a braided flat wire of thin metal wire, silver paint, etc. Particularly suitable for the present invention are those in which conductive paint is provided in a band shape, such as the following.

In addition, in FIGS. 1 and 2, an example in which the current-carrying electrode band 3 is provided at the end of the planar conductor 2 is explained.
When provided in the center of the planar conductor 2, the current-carrying electrode band 3 can be laminated on both sides in the width direction with an electrically insulating layer 4 interposed therebetween.

Next, the electrically insulating layer 4 may be a plastic film, a sheet, an electrically insulating paint film, or the like.

By the way, the method for manufacturing the planar heating element of the present invention is arbitrary, but the following method is particularly suitable for providing the electric insulating layer 4. However, it is not limited to this.

(Example 1) Base material 1 made of biaxially stretched polyester film
A tape-shaped electrical insulating layer 4 made of biaxially stretched polyester film is provided in advance on a planar conductor 2 coated with a conductive paint made of conductive carbon powder and a binder resin. By staggering the current-carrying electrode strips 3 made of metal foil tapes, a planar heating element of the present invention as shown in FIG. 1 can be obtained. Note that the inner end of the electrically insulating layer 4 is located at the same position as the inner end of the current-carrying electrode band 3 or at a position further inside, which prevents electrical contact between the current-carrying electrode band 3 and the planar conductor 2 on the inside. It is necessary for Of course, the outer end of the electrically insulating layer 4 is located inside the outer end of the current-carrying electrode band 3 in order to ensure electrical contact between the current-carrying electrode band 3 and the planar conductor 2 at the outer end portion. is necessary. Further, in this example, the electrical insulating layer 4 is shown as two tape-like bands on the left and right sides, but a single wide band formed by extending the two and connecting them on the inside can also have the same function as required for the present invention. Further, when providing two tapes, there is also a method in which the electrical insulating layer 4 and the current-carrying electrode band 3 are stacked and laminated in advance with an offset, and then these are provided on the planar conductor 2. Alternatively, the electrically insulating layer 4 may be provided as a paint layer. There is also a method in which the current-carrying electrode band 3 is provided in the form of a band using silver paint.

(Example 2) Inside the current-carrying electrode band 3 made of metal foil tape,
Biaxially stretched polyester film tape is bonded in a U-shape with a suitable adhesive to form an electrical insulating layer 4.
By embedding this in a planar conductor 2 made of a polyethylene sheet kneaded with conductive carbon powder, a planar heating element of the present invention as shown in FIG. 2 can be obtained. Further, as the electrical insulating layer 4, the current-carrying electrode band 3 may be coated with polyester, epoxy resin, etc., or polyethylene may be melt-extruded and coated. In particular, as in the latter case, it is preferable that the non-conductive component of the planar conductor 2 be shared with the electrical insulating layer 4, since the adhesion between the two is good. Note that methods for embedding the current-carrying electrode band 3 and the electrically insulating layer 4 at both ends of the planar conductor 2 include melt extrusion embedding as in the case of covering electric wires, or dividing the planar conductor 2 into two sheets. The electrically conductive electrode band 3 and the electrically insulating layer 4 may be sandwiched between them and bonded together by thermocompression to be integrated and embedded. Particularly in the latter case, there is an advantage that a tape-shaped electrical insulating layer 4 as shown in (Example 1) can be used.

Although FIGS. 1 and 2 show an example in which there are two common electrode bands 3, the present invention can be similarly applied to a case in which there are three or more common electrode bands 3.

As described above, the planar heating element of the present invention is a planar heating element in which a current-carrying electrode band is provided on a planar conductor, in which the current-carrying electrode band has an electrically insulating layer on at least one side in the width direction of the current-carrying electrode band. By using a planar heating element characterized by being laminated with a planar conductor through a conductor, the thickness of the current-carrying electrode band can be made thin and wide, and the current-carrying electrode band portion It has a small non-heat generating area, has excellent flexibility, easily recovers from wavy deformation, does not create gaps during installation, does not impair heat conduction, and can easily provide a planar heating element with a large current carrying capacity. It is something. In addition, since it has become possible to widen the width of the current-carrying electrode band, if it is made of metal foil, it produces a heat-uniforming effect and contributes to improving the temperature at the end of the planar heating element. Since the insulating layer protrudes inward at the same time as or more than the inner end of the current-carrying electrode band, it also has the effect of preventing the defect that the burr at the inner end of the current-carrying electrode band bites into and cuts the planar conductor. Of course, this method requires less construction work and is superior in productivity compared to the conventional method in which a bypass wire is provided to a planar heating element with a small current-carrying electric capacity and double connection is made appropriately.

Therefore, the planar heating element of the present invention is suitable for heating and insulating industrial tanks and pipes that require large current-carrying capacity and length, and for melting snow on roads and roofs. Needless to say, it can also be applied to mats, electric tatami mats, electric floor panels, etc.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing one embodiment of the sheet heating element of the present invention. DESCRIPTION OF SYMBOLS 1... Base material that also serves as an electrical insulator, 2... Planar conductor, 3... Current-carrying electrode band, 4... Electrical insulating layer, 5
...Electrical insulator.

Claims (1)

[Scope of utility model registration request] A planar heating system in which a planar conductor is formed between base materials that also serve as electrical insulators, and current-carrying electrode bands are provided on or within the planar conductor on either side or between both sides in the width direction. In the body, the current-carrying electrode bands provided on both sides in the width direction are laminated with a planar conductor through an electrically insulating layer on the inner side, and the current-carrying electrode band provided in the middle in the width direction is A planar heating element characterized in that both sides are laminated with planar conductors with an electrically insulating layer interposed therebetween.