JPH07114975A - Heating structure body to be buried - Google Patents

Abstract

PURPOSE:To prevent deformation and sinking of the surface of asphaltpaved road so as to improve adhesion between a heater and asphalt and to improve insulation of the heater by burying a snow melting heater in the road. CONSTITUTION:At least two heating element structure 1 to be buried under ground, for which the entire surface or one surface of an electric heater is covered with sheet dipped in a asphalt, a power source cord 2 of the heating element structure to be buried under ground, the end of the power source cord and a power feeding cord are crimped and are connected to each other. The connected part is covered with a resin cover of thermal deformation temperature of not less than 50 deg.C. An electrically insulating resin is sealed in the resin cover, and one or more divided connectors 3 which are hardened, are provided. Insulation of the connected part with the power feeding cord, etc., is improved, and there is no possibility of discontinuity or negation of insulation due to the pressure or heat during burying work, while safety and durability are ensured. Since the structure is formed in a unit, workability is improved and heater wiring can be simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating structure for embedding, which is suitable for melting road snow such as road heating on sidewalks and roads, parking lots, entrance porch and the like. INDUSTRIAL APPLICABILITY The present invention can be widely used for applications such as floor melting and snow melting on roads and parking lots.

[0002]

2. Description of the Related Art In snowfall areas, prevention of snow accumulation and prevention of freezing in various places has become an issue. In particular, snow removal on roads (slopes), sidewalks, and roads near the building entrance is essential for daily life, and has attracted a great deal of attention as a result of mandatory use of studless tires. Snow removal methods are roughly classified into snow removal and snow melting, but an automatic snow melting method that does not require human labor is desired, and therefore various snow melting heaters have been devised.

A buried heater system for the purpose of melting snow on a road surface has been conventionally constructed by a method of circulating hot water obtained by burning kerosene or city gas in a buried pipe, and a heat pump (heat exchange). A method of circulating hot water in an embedded pipe, a method of heating with a heating wire or a planar heating element by electric energy (Japanese Patent Publication No. 54-16653, Japanese Patent Publication No. 50-8340, etc.) are known. There is. When burying these heaters in the asphalt roadbed, the asphalt may be subjected to rolling loads during construction, vibrations when cars or people pass on the road, or expansion and contraction due to expansion and cooling during energized heating. There is a problem that strain occurs at the interface between the layer and the heater (pipe or heating element), and the road surface is deformed, depressed, or cracked.

As a solution to such a problem, a method of embedding a wire mesh together with a heater (Japanese Patent Laid-Open No. 11540/1990).
No. 4), and a method of fixing the heater pipe to a fixed base material provided separately during burying (Japanese Patent Publication No. 53-4740), but the versatility is poor and the construction is troublesome. Not only that, the adhesion between the asphalt and the heater is not essentially strengthened, so the effect is not sufficient. On the other hand, even when using an existing crack prevention sheet (polyester non-woven fabric, etc.), the slip generated at the interface between the heater and the sheet and asphalt layer remains,
The deterioration of the roadbed surface is not sufficiently improved.

On the other hand, when burying a road snow melting heater on a road surface, a method is generally used in which after arranging the sheet heaters on the road surface, laying asphalt on the surface with a finisher and rolling. ing. However, in this case, since it is necessary for the equipment for road paving and workers to ride on the sheet heater directly to carry out the construction, the position and arrangement of the heater may be displaced during the construction, Alternatively, there is a problem that a heater is caught in or damaged by a tire or a caterpillar of a pavement vehicle.

In order to solve this problem, the present inventors covered the heater (heating element) with a non-woven fabric impregnated with asphalt rather than using a strong resin (for example, a curable resin). By burying it later, not only cracks and depressions on the road surface can be prevented, but also the heating element can be mechanically protected, insulation failure can be prevented, and at least the bottom surface of the heating element structure for burying can be prevented. By providing an adhesive surface and fixing it to the base etc., we found that the position and arrangement of the heater did not shift during asphalt construction, and the burial work could be performed easily, and we have already filed an application based on this knowledge. (Japanese Patent Application 5-1
22106).

According to such a buried heating element structure,
Not only can cracks and depressions be prevented on the road surface, and moreover, not only mechanical protection of the heating element can be achieved, but also insulation failure can be prevented. By the way, in the heater in such a buried heating element structure, the electric power supply wire must be connected to the main line of commercial electric power. At this time, the wiring and construction are simplified by burying the connection with the main line as well as the heater. In this case, generally, the coating of each electric wire is removed, each wire is connected and fixed by a crimp terminal or the like, and further, insulation sealing is performed with an insulating tape or the like.

However, this method has a problem that the insulation is destroyed by the pressure (rolling load) and heat at the time of burying. In particular, when road construction is performed with asphalt, a temperature of 150 to 180 ° C. is applied to these connecting portions, so that the covering material such as the insulating tape is melted or deformed, and the insulation is easily broken. .

In order to prevent such dielectric breakdown due to deformation and melting, a protective cover is generally provided at the connection portion. However, when a large cover is used for embedding, there are problems such as cracks on the surface of the ground surface and corrosion of a metallic cover.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems, and when melting snow on the ground such as road heating of sidewalks and roads, parking lots, entrance porch, etc. Prevents deformation and depression of the asphalt pavement caused by burying a snow melting heater, improves the adhesion between the heater and asphalt, insulation of the heater, and insulation of the connection part, and also by pressure and heat during burial work. It is an object of the present invention to provide a heat generating structure for embedding which does not have a risk of insulation breakdown.

[0011]

Means for Solving the Problems That is, the present invention provides two or more of a heating element structure for underground embedding (1) in which the entire surface or one side of an electric heater is covered with an asphalt-impregnated sheet, and the heat generation for underground embedding. The power cord (2) of the body structure and the end of the power cord and the power supply cord are connected by crimping, and the connecting portion is covered with a resin cover having a heat distortion temperature of 50 ° C. or higher, and (EN) A heat generating structure for embedding which has one or more branch connectors (3) obtained by encapsulating and curing an electrically insulating resin inside a resin cover.

The embedded heating structure of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an explanatory view showing one mode of the embedded heating structure of the present invention. In the figure, reference numeral 1 is a submerged heating element structure, reference numeral 2 is a power cord for the submerged heating element structure, and reference numeral 3 is a branch connector. Further, FIG. 2 is a cross-sectional view showing one mode (a surface of an electric heater covered on both sides) of the heating element structure 1 for underground embedding used in the present invention. FIG. 3 is a cross-sectional view showing another embodiment (one side of an electric heater is covered) of the underground heating element structure 1 used in the present invention. FIG. 4 shows one mode of a branch connector using a three-way crimp terminal, and (a) is a partially cutaway plan view showing one mode of a branch connector using a three-way crimp terminal. b) is a side view thereof.

Underground heating element structure 1 used in the present invention
Is an electric heater 4 whose entire surface or one surface is covered with an asphalt-impregnated sheet 5. Here, examples of the electric heater (heating element) 4 include a linear sheath heater and an electric planar heater. Here, the electric planar heater is made of, for example, resin and a composite material such as metal powder, carbon black, graphite, metal wire mesh, metal non-woven fabric, carbon fiber woven fabric, short carbon fiber non-woven fabric, and the like. It is suitable as a heating element buried in the ground because of its excellent heat resistance, insulation characteristics and handleability.

More specifically, such an electric type planar heater is, for example, a high-density polyethylene resin, a low-density polyethylene resin, a polypropylene resin, an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer (EV).
A), ethylene-ethyl acrylate copolymer (EEA)
Olefin resin such as, trans-1,4-polyisoprene, polyamide, polyester, fluorine-containing ethylene copolymer and other thermoplastic resins, carbon black, graphite, metal powder, metal wire mesh, metal non-woven fabric, carbon fiber woven A sheet made of a composition obtained by adding a conductive substance such as a non-woven fabric or a non-woven fabric is attached with an electrode and further with a power cord (lead wire) 2 described later. further,
Various heating elements such as carbon black and other conductive materials and resin components dissolved in a solvent, a so-called conductive paint impregnated into a fibrous sheet and cured, or a heating element made of carbon fiber mixed paper One of these heating elements can be used.

Underground heating element structure 1 used in the present invention
Is the one in which the electric heater 4 for heating the roadbed surface is covered with the asphalt-impregnated sheet 5 on all or one side. Here, the entire surface of the electric heater 4 for heating the road surface is
The asphalt-impregnated sheet 5 need not be covered, and only one side (preferably the upper surface) may be covered with the asphalt-impregnated sheet 5. FIG. 2 shows the electric heater 4 for heating the roadbed surface entirely covered with the asphalt-impregnated sheet 5. FIG. 2 shows one side of the electric heater 4 for heating the roadbed (in the figure, The upper surface) shows the one covered with the asphalt-impregnated sheet 5.

Examples of the asphalt-impregnated sheet 5 include sheet-like molded articles such as non-woven fabric, woven fabric, glass cloth and paper made of polyester or the like and impregnated with asphalt. In addition to asphalt, synthetic rubber, liquid rubber,
Fillers such as thermoplastic resin, sand, calcium carbonate, glass beads, and glass balloons may be added. The thickness of the asphalt-impregnated sheet 5 is usually 0.3.
Those having a thickness of 10 to 10 mm, preferably 1 to 5 mm are used.

With such an asphalt-impregnated sheet 5,
When coating the electric heater 4 for heating the roadbed surface,
For example, at least one of the front and back surfaces of the asphalt-impregnated polyester nonwoven fabric may be coated with a special rubberized asphalt compound or the like as an adhesive to form an adhesive surface, and release paper may be attached to the adhesive surface. If such a material is used, the adhesive surface, which appears when the release paper is peeled off, can be simply coated by pressing it on the electric heater 4 for heating the roadbed surface. In this way, if the asphalt-impregnated sheet 5 is coated on the entire surface or one surface (upper surface or lower surface) of the electric heater 4 for heating the roadbed surface, the heating element structure 1 for underground embedding used in the present invention 1 Can be easily obtained.

Further, in order to firmly fix the underground burying heating element structure 1 to a base or the like, the underground burying heating element structure 1
It is preferable to provide an adhesive surface on at least the bottom surface. In this case, the asphalt-impregnated sheet 5 to be adhered to the lower surface side of the electric heater 4 for heating the roadbed surface is coated with an adhesive to form an adhesive surface, and release paper is attached to the adhesive surface. If used, the coating of the electric heater 4 for heating the roadbed surface and the formation of an adhesive surface on at least the bottom surface of the underground heating element structure 1 (and thus fixing to the ground) can be performed almost simultaneously. The construction is remarkably easy. That is, after peeling off the release paper on the surface of the asphalt-impregnated sheet 5 to be stuck on the lower surface side of the electric heater 4 for heating the roadbed surface, and after sticking it on the electric heater 4 for heating the roadbed surface to cover it, At the construction site, the release paper on the back surface of the sheet 5 can be peeled off, and the sheet 5 can be fixed by being attached to the construction surface such as a base. Of course, an electric heater 4 for heating the road surface
An adhesive surface may be provided not only on the bottom surface but also on the upper surface side.
In this case, an adhesive is applied to both the front and back surfaces of the asphalt-impregnated sheet 5 to be attached to the upper surface side of the electric heater 4 for heating the roadbed surface, and release paper is attached to this adhesive surface. You can use it. If the asphalt-impregnated sheet 5 covers the electric heater 4 for heating the road surface only on the upper surface and not on the lower surface (for example, in the case of FIG. 3), the electric heater for heating the road surface is used. The adhesive may be applied directly to the heater 4 to form an adhesive surface.

The electric heater 4 in the underground heating element structure 1 is usually supplied with electric power from commercial electric power. Therefore, a power cord (lead wire) 2 made of a heat-resistant electric wire is connected to the electric heater 4 in the underground heating element structure 1. In the embedded heating structure of the present invention, the end of the power cord (lead wire) 2
The power supply cord (main line) 6 is connected using the crimp terminal 7. At this time, naturally, the coating on the end of each cord is removed. In addition, power supply cord (main line) 6
May be connected to another trunk line at the surface of the earth, for example.

In the burying heat generating structure of the present invention, two or more underground burying heat generating structures 1 are used, and two or more power cords (lead wires) 2 are also present.
The ends of the two or more power supply cords (lead wires) 2 and the power supply cord (main wire) 6 are connected using the crimp terminal 7.

The present invention is characterized in that this connecting portion is connected using a specific branch connector 3. That is, according to the present invention, the branch connector 3 is formed by covering the above-mentioned connecting portion with the resin cover 8 having a heat distortion temperature of 50 ° C. or more, and encapsulating an electrically insulating resin inside the resin cover 7 and curing the resin. One or two or more are used. In the present invention, the connecting portion connected by the crimp terminal 7 does not use an insulating tape as in the conventional case, but
The branch connector 3 is covered with a resin cover 8, and an electrically insulating resin for insulation and sealing is enclosed (filled) in the resin cover 8 and cured to form the branch connector 3.

The crimp terminal 7 is not particularly limited as long as it can connect the ends of two or more power cords (lead wires) 2 and the power supply cord (main wire) 6 and is not particularly limited. What is used may be used. For example, a two-way crimp terminal that crimps in two directions, a three-way crimp terminal that crimps in three directions, or a four-way crimp terminal that crimps in four directions can be used. FIG. 4 shows an example of a branch connector using a three-way crimp terminal. Normally, two-way crimp terminals and three-way crimp terminals are used when connecting one end of the power cord (lead wire) 2 to one power supply cord (main line). It is used when connecting one end of the power cord (lead wire) 2 to one power supply cord (main line). By using such a crimp terminal, inserting the ends of two or more power cords (lead wires) 2 and the power supply cord (main line) 6 into the crimp terminal, and then caulking with a metal fitting or the like. , Connect these.

The connection portion thus connected is covered with a resin cover 8 in which an electrically insulating resin for insulation and sealing is sealed and cured to form a branch connector 3.
Here, as the resin cover 8, the heat distortion temperature (ASTM
Measured in accordance with D648-56, 18.56k
A resin made of a resin having a heat resistance of 50 ° C. or more (g / cm ² load) is used. Examples of the resin suitable for such a resin cover include engineering plastics such as polyacetal, polycarbonate, polyamide, polyphenylene sulfide, saturated polyester, polysulfone, polyarylate, polyphenylene sulfide, and ABS resin. Further, these and glass fiber, etc. A composite with the reinforcing material of is also used. However, as a reinforcing material in this case, it is natural to use a material that does not impair the electrical insulation of the connector.

Further, a phenol resin, an unsaturated polyester resin, an epoxy resin, a polyimide resin, a polyamideimide resin, a maleimide resin or the like can be used, and these polymer alloys can also be used. Further, if heat resistance is required, high heat resistant thermoplastic resins such as polyether ether ketone and polyether nitrile can be used. The resin cover 8 of the present invention may be formed in a shape suitable for branching by considering the shape of the crimp terminal 7 and the like by a method such as injection molding or press molding of these resins. FIG. 4 shows a branch connector 3 having a resin cover 8 which is branched in three directions. It should be noted that the resin cover 8 may be divided into, for example, upper and lower halves in consideration of the mountability.

An electrically insulating resin for insulation and sealing is enclosed in the resin cover 8 and hardened to form the branch connector 3. The branch connector 3 needs to maintain good electrical insulation, and as the internal insulating sealing material with which the resin cover 8 is filled, the volume resistivity (JIS K6911) is used.
Is 1 × 10 ⁵ Ω · cm or more, and the dielectric breakdown voltage (
According to JIS K6911), it is preferable to use a resin of 1 kv / mm or more.

As such a resin, for example, an epoxy resin (one-liquid type, two-liquid type) having an insulating property, a room temperature curable resin such as a urethane resin or a silicone resin, and a resin curable by heating are preferable, but polypropylene, A hot-melt sealant such as ethylene-vinyl acetate copolymer (EVA) or polyamide can also be used. Further, a connector having excellent flexibility can be obtained by using the foamed body of the above resin. The method of encapsulating the electrically insulating resin is not particularly limited, but the upper and lower resin covers 8 are sandwiched, and the upper and lower resin covers 8 are joined together by thermocompression bonding or super bonding. The simplest method is sonic welding and then injecting the molten resin into the resulting gap.

The heat generating structure for embedding of the present invention comprises two or more of the heat generating structure 1 for underground embedding as described above, the power cord 2 for the heat generating structure for underground embedding, and the branch connector as described above. And one or more than three. The number of the underground heating element structures 1 to be installed may be appropriately selected according to the size of the place where snow melting is required and the like. Usually, one having about 2 to 10 heating element structures 1 for underground burying,
It is preferable in terms of handling. The number of branch connectors 3 to be installed varies depending on the number of the underground heating element structures 1 to be installed. In FIG. 1, the lower side of the figure is arranged in parallel in the same manner as the state shown in the figure, with the heating element structure 1 for underground burying.
An appropriate number of branch connectors 3 and branch connectors 3 may be installed, or the underground-embedded heating element structure 1 may be connected via the power cord 2 with this as an end. Further, in the state shown in the drawing, the underground-embedded heating element structure 1 may be connected to the right side of the branch connector 3 via the power cord 2. In this case, a four-way crimp terminal may be used instead of the three-way crimp terminal as shown in the figure.

The branch connector 3 having the connection portion completely insulated as described above is buried in the ground integrally with the underground heating element structure 1. At this time, the branch connector 3 It is advisable to cover the upper and lower surfaces or the lower surface with an asphalt-impregnated sheet. As a result, the rolling load applied by the road roller during construction can be further alleviated, and damage and insulation failure can be further reduced.

As such a covering material, an asphalt-impregnated sheet as described as a covering material for the electric heater 4 for heating the road surface is used. Specifically, for example, a surface of an asphalt-impregnated polyester nonwoven fabric is used. It is preferable that at least one surface of the back surface is coated with a special rubberized asphalt compound or the like as an adhesive to form an adhesive surface, and release paper is attached to the adhesive surface. If such a material is used, the adhesive surface that appears when the release paper is peeled off can be easily covered by simply pressing it onto the branch connector 3.

Further, as described in the description of the electric heater 4 for heating the roadbed surface, it is preferable to further provide an adhesive surface coated with an adhesive on at least the bottom surface of the branch connector 3. As a result, there is no deviation during construction,
The construction is simple, and the breakage of the branch connector 3 is almost eliminated.

Since the buried heating structure of the present invention has a plurality of the underground buried heating elements 1 as a set and is wired, it is very easy to bury. It is also possible to protect from the pressure and temperature at the time of burial by shaving the roadbed of the portion where the branch connector 3 and the power supply cord (main line) 6 are laid and installing it in the ground.

The heat generating structure for embedding of the present invention has a structure as described above. However, such a structure is fixed as it is, preferably with an adhesive surface, to the construction surface, and a surface layer portion is provided thereon. By being provided and buried in the roadbed, it becomes a buried structure. As described above, the buried heating structure of the present invention is used by being buried in the roadbed, but since the asphalt sheet 5 is used, the familiarity with the roadbed is strengthened at this time.

The subgrade is usually provided with an asphalt stabilizing layer consisting of a crushed stone layer and a mortar layer on the roadbed, on which a coarse-grained asphalt concrete layer as a base and a dense-grained asphalt concrete layer as a surface layer. Although it has a structure in which a layer is provided, there is also a structure in which a surface layer is provided on a roadbed or asphalt stabilization layer. The heat generating structure for embedding of the present invention is usually buried in the boundary surface between the surface layer of asphalt, concrete or the like and the base layer which is the construction surface as described above to form an embedding structure. It is also possible to further prevent the surface layer from being displaced by laying the embedded heating structure at a certain interval and providing a portion where the surface layer is in direct contact with the roadbed and the ground.

The construction surface may be a surface such as a road surface, and the surface is preferably a flat surface, but may be a gently curved surface. The construction surface is generally an underlayer, that is, an asphalt layer or a crushed stone layer, but may be wood or brick. In addition, since it uses a sticking method, it can be installed on a wall surface in some cases, and if it is a road,
It can also be used on slopes and the like.

When fixing the embedded heating element structure 1 or the like to a construction surface such as a base, the road surface may be heated to increase the adhesive strength, or an appropriate emulsion may be sprayed. It is possible. Alternatively, the adhesive layer may be directly applied to the road floor surface to fix the embedded heating element structure 1 and the like.

In this way, by ordinary road pavement work,
By embedding the embedded heating element structure 1 and the like, the embedded heating element structure is obtained. When constructing the surface layer, generally, asphalt is sprayed with an asphalt finisher and compacted with a road roller, a vibration roller, a tire roller or the like. In the present invention, since the buried heating element structure 1 and the like can be firmly fixed to the construction surface such as the base, even if the worker works on the paving equipment, the heating element structure 1 However, there is no problem such as a portion that is overheated when energized or a portion that does not generate heat on the contrary due to the movement of the components, or the arrangement being displaced. Moreover, since a specific branch connector is used, there is almost no risk of the insulation of the connection portion being destroyed.

[0037]

EXAMPLES Next, the present invention will be described in detail with reference to Examples. Example 1 A sheet heating element (200 W / 200 V, length 2250 mm, width 200 m) sealed on both sides with a polyester film.
m, thickness 0.7 mm) was joined with a power cord (lead wire) 2 to obtain an electric heater 4 for heating the road surface. On the other hand, as the asphalt-impregnated sheet 5, one in which an asphalt-impregnated polyester non-woven fabric is coated with a rubber-containing asphalt compound as an adhesive (for upper surface 5
a) and an asphalt-impregnated polyester non-woven fabric coated with asphalt compound on both sides (5b for lower surface) were prepared (thickness: 1.5 mm). At this time, release paper was attached to the adhesive surface to prevent the adhesion and facilitate the handling. Peel off the release paper of the asphalt-impregnated sheet 5 (5a for the upper surface and 5b for the lower surface) on the front and back surfaces of the electric heater 4 for heating the roadbed surface (however, do not remove the release paper on the bottom surface of the lower surface 5b). With)
A heating element structure 1 for underground embedding having an adhesive surface with a release paper on the bottom was produced. 100 pieces of such heating element structures 1 for underground burying were produced. First, for 10 of them, the power cord (lead wire) 2 end and the power supply cord (main line) 6 are used for power supply by using a three-pronged crimp terminal 7 as shown in FIG. After connecting from the cord (main line) 6 to the underground-embedded heating element structure 1 side in parallel in a T-shape one by one, polyphenylene sulfide (heat distortion temperature: 250 ° C.) so as to cover this connection part A resin cover 8 (maximum length 90 mm) composed of two parts was covered and then adhered by ultrasonic welding. An epoxy type encapsulant was injected into the resin cover 8 and cured to form the branch connector 3. The volume resistivity of this encapsulant is 2 x
It was 10 ¹⁶ Ωcm, and the dielectric breakdown voltage was 20 KV / mm 2. In this way, an embedded heating element structure having 10 underground embedded heating element structures 1, 20 power cords (lead wires) 2 and 20 branch connectors 3 was produced. A heat resistant wire was used for wiring.

Hereinafter, for the remaining 90 buried heating element structures 1 for underground embedding as well, in the same manner as described above, 10 embedding heating element structures 1 for underground embedding and 20 power cords (lead wires)
A heating structure for embedding having 2 and 20 branch connectors 3 was prepared, and a total of 10 sets of heating structures for embedding were prepared. The 10 sets of buried heating structures obtained in this way (embedded heating structure consisting of a total of 100 underground buried heating structures 1) are distributed between the buried heating structures 1 in various locations. They were laid on the coarse-grained asphalt at intervals such that the pitch was 200 mm. When laying, markings were made on the road surface (base) at intervals of 200 mm, the release paper on the bottom surface of the underground heating element structure 1 was peeled off, and the road surface (base) was attached at even intervals. A fine grain asphalt concrete at 150 ° C. is spread on it with a finisher to a thickness of 50 mm, and 30 kgf / cm using a road roller, a vibration roller, and a tire roller.
^It was compacted by the load of ² and buried. After the construction, there were no irregularities or cracks on the road surface, and the appearance was good. In addition, the power supply cord (main line) 6 was connected to another main line, which is a base, by a conventional method at the ground surface portion by a terminal board. After the construction, when a voltage of 200 V was applied to the embedded heating structure, the asphalt surface reached 5 ° C. in about 30 minutes and 14 ° C. in about 1 hour when the temperature was 0 ° C., and the temperature raising effect was confirmed. The insulation resistance of the heater was measured after it was left for 6 months under natural conditions (when there was passing of the vehicle with 200V energized and there was snow and rain), and it was 1 GΩ or more, and insulation was maintained. .

COMPARATIVE EXAMPLE 1 In Example 1, the resin cover 8 and the epoxy type encapsulant were not used, and instead, the portion connected using the crimp terminal 7 was electrically insulating tape (on the base material of ethylene / propylene rubber). Butyl rubber-based mustic was applied as an adhesive layer) was wrapped around and insulated, and the number of sheets was 1 set (1
The same procedure as in Example 1 was carried out except that the number of sheets was 0. The volume resistivity of this tape is 4 × 10 ¹⁵ Ωc
m, and the dielectric breakdown voltage was 20 kv / mm. This tape was flexible on rubber at room temperature. With this tape itself, there was no change in the tensile strength even when heated at 100 ° C. for 24 hours. The insulation resistance of this embedded heat generating structure was 1 GΩ or more immediately after the construction, but after the lapse of one month under the same natural conditions as in Example 1, it was 20
It has fallen below kΩ.

[0040]

INDUSTRIAL APPLICABILITY The buried heating structure of the present invention prevents deformation and depression of the asphalt pavement caused by burying a snow melting heater, improves adhesion between the heater and asphalt, and improves insulation of the heater. Insulation of the connection with the power supply cord (main line) etc. has been improved, and due to pressure and heat at the time of burial work, disconnection,
There is no danger of the insulation being broken, and it has excellent safety and durability. That is, in the embedded heating structure of the present invention, not only the adhesion between the heater and the asphalt and the insulation of the heater are improved, but also the insulating property of the connection portion between the power supply cord (main line) and the power cord is effective. Since it is protected, it does not deteriorate its insulation property for a long period of time during or after burial construction, and is excellent in safety. Further, since the embedded heating structure of the present invention is unitized, it is possible to improve workability. Furthermore, during and after burial construction, there is no risk of irregularities or cracks on the road surface, and durability is improved. Further, since the embedded heating structure of the present invention is unitized, the heater wiring can be simplified. Therefore, the buried heating structure of the present invention can be used very effectively for road heating and the like for snow melting.

[Brief description of drawings]

FIG. 1 is an explanatory view showing one embodiment of a buried heating structure of the present invention.

FIG. 2 is a cross-sectional view showing one mode (electric heater of which both surfaces are covered) used for the underground heating element structure 1 used in the present invention.

FIG. 3 is a cross-sectional view showing another mode of the underground-embedded heating element structure 1 (one side of an electric heater is covered) used in the present invention.

FIG. 4 shows an embodiment of a branch connector using a three-way crimp terminal, and FIG. 4 (a) is a partially cutaway plan view showing an embodiment of a branch connector using a three-way crimp terminal. And (b) is a side view thereof.

[Explanation of symbols]

 1 Underground heating element structure 2 Underground heating element structure power cord 3 Branch connector 4 Electric heater for road surface heating 5 Asphalt impregnated sheet 6 Power supply cord (main line) 7 Crimping terminal 8 Resin cover

Claims (1)

[Claims] 1. A heating element structure for underground embedding (1) in which at least one surface of an electric heater is covered with an asphalt-impregnated sheet, and a power cord (2) for the heating element structure for underground embedding. And the end of the power cord and the power supply cord are connected by crimping, and the connecting portion is covered with a resin cover having a heat distortion temperature of 50 ° C. or higher, and an electrically insulating resin is provided inside the resin cover. An embedded heating structure having one or more branch connectors (3) which are encapsulated and cured.