JPH08255673A - heater - Google Patents

Abstract

(57) [Summary] [Structure] The heater body 1 is encapsulated by extrusion molding of the heater body 1 in a cord-shaped heater body 1 having electrical insulation and flexibility. The heating element 2 has a cylindrical shape and has electrodes 7a and 7b on its inner peripheral surface and outer peripheral surface, respectively. Each power supply line 3 for energizing this heating element 2
The electrodes 7a and 7b are connected to each other. [Effect] One power supply line 3 is connected to the electrode 7 on the inner circumference of each heating element 2.
and the other power supply line 3 is connected to an arbitrary part of the electrode 7b on the outer periphery of each heating element 2. At this time, since the respective power supply lines 3 and the respective heat generating elements 2 can be connected to arbitrary contact parts, the power supply lines 3 and the electrodes 7a, 7 of the respective heat generating elements 2 can be connected.
Positioning for connection with b becomes easier than before.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater which can prevent water from being frozen at a staying site by heating a staying site where water is collected, such as a water pipe.

[0002]

2. Description of the Related Art Conventionally, in order to prevent the freezing of water such as a water pipe, US Pat. No. 4,728,48 discloses a heating cable as a cord-shaped heater. As shown in FIG. 9, the heating cable includes a main body 51, which is a cable-shaped insulator made of a thermoplastic resin 54, and a rectangular parallelepiped heating element 52, which is a positive temperature coefficient thermistor.
A plurality of them are sealed along the length direction of the sheet 1 at a predetermined interval. At this time, the heating element 52 is
After alignment between the power supply lines 53, the power supply lines 53 are connected to the respective power supply lines 53 via solder 55.

As a method of manufacturing the heating cable, it has been considered that the heating cable is manufactured continuously and integrally formed by extrusion molding in order to suppress the manufacturing cost. That is, for example, as shown in FIG. 10, in the above heating cable, when the molten thermoplastic resin 54 'is extruded from each nozzle 58 in the extruding direction B and integrated into a cord shape, the feed lines 53 parallel to each other are extruded. Each heating element 52 coupled between
Is covered with the extruded thermoplastic resin 54 ', so that the power supply lines 53 and the heating elements 52 are enclosed in the cord-shaped main body 51 in which the molten thermoplastic resin 54' is integrated.

[0004]

However, in the above-described conventional structure, each heating element 52 is connected to each power supply line 53 by the solder 55.
In order to connect with the above, it is necessary to accurately align both of them in advance and maintain the positional relationship between the both until they are joined by the solder 55. If this alignment is insufficient, it is not possible to supply power to each heating element 52 satisfactorily. Therefore, there is a problem that it takes time to electrically connect the both in order to reliably supply the electric power.

[0005]

In order to solve the above problems, the heater of the present invention has a main body having electrical insulation and flexibility, which is provided in a cord shape by extrusion molding of synthetic resin, and has a positive temperature coefficient thermistor. A plurality of heating elements formed of ceramics in a cylindrical shape are provided in the main body along the length direction of the main body, and a pair of power supply lines for supplying power to the respective heating elements are provided in the main body. Each of the electrodes connected to each of the power supply lines is formed on the inner peripheral surface and the outer peripheral surface of the heating element so as to extend in the circumferential direction.

[0006]

According to the structure of the present invention, the main body is formed by covering the respective heating elements coupled between the mutually parallel power supply lines with the flexible thermoplastic resin. Further, in the above configuration, each electrode is provided on the outer peripheral surface and the inner peripheral surface of the heating element having a cylindrical shape, and one of the power supply lines is brought into contact with the electrode on the inner peripheral surface of the heat generating element. The other power supply line can be connected to the electrode on the outer peripheral surface of the heating element by passing through the heating element.

Therefore, since the main body has an electric insulation property, the heating element can be energized through each power supply line while maintaining the electric insulation property between the respective power supply lines. Thereby, even with respect to the curved surface of the object to be heated, it is possible to efficiently heat the surface by the heating element along the flexible main body along the surface.

By the way, in the prior art, when connecting each feeder to each heating element, in order to securely connect each feeder to the electrode surface of each heating element, both of them are aligned and the both are connected. Power was stably supplied to each heating element.
At this time, in order to obtain a good power supply, a time-consuming process of accurately performing the above-mentioned alignment is required.

However, in the above structure, the respective power supply lines and the contact portion of the heating element can be connected at any positions along the circumferential direction of the inner peripheral surface and the outer peripheral surface of the heating element, so Positioning for connecting the heating element to each electrode becomes easier than before.

[0010]

【Example】

[Embodiment 1] One embodiment of the present invention is shown as Embodiment 1 in FIG.
The following description is based on FIG. 1 to 3
As shown in FIG. 2, the heater of the first embodiment has a heater body 1 made of ceramics, which is a positive temperature coefficient thermistor that generates heat when electricity is applied to a flexible and long cord-shaped heater body 1.
Are provided at predetermined intervals in the length direction of the heater body 1.

The above-mentioned cord shape means an electric wire shape having a circular or elliptical cross section or a strip shape having a rectangular cross section.
This type of heater serves as a water retention site of a water pipe or the like, and can heat the object to be heated having a curved surface along the surface thereof. There is.

The heater body 1 has a covering member 4 made of vinyl chloride resin having an electric insulation property. Further, in order to supply power to each of the heating elements 2, the heater body 1 is provided in the length direction of the heater body 1. It is provided with a pair of flexible power supply lines 3 and 3 arranged so as to be parallel to each other. Therefore, the heating elements 2 are connected to the power supply lines 3 so as to be electrically parallel to each other at predetermined intervals between the power supply lines 3, and the long heat generating unit 10 is connected together with the power supply lines 3. Is forming.

Further, the heater body 1 is made of a thermoplastic resin 4'having electrical insulation, flexibility and weather resistance as the covering member 4, for example, vinyl chloride resin, and having a length of 1000 m and a diameter of 6.0 mm, for example. Are formed to have respective dimensions. The weather resistance is a property that is excellent in heat resistance and cold resistance and has little change in physical properties even if heating at about 50 ° C. and cooling at about −10 ° C. are repeated. Therefore, the heater body 1 has a characteristic that it is very easily bent.

The power supply line 3 is composed of a gathered wire such as a braided wire in which thin copper wires are twisted together. For this reason, since the power supply line 3 is easily bent and no restoring force is generated even if it is bent, the heater main body 1 of the present embodiment has a large axis even if it is a water pipe having a large curvature, that is, a small diameter. It can be spirally wrapped around the outer surface of the water pipe without difficulty. Therefore, when the water pipe is covered so as to be crimped along the length direction of the water pipe, the heater body 1 can be crimped to the bent portion of the water pipe, and the water pipe can be efficiently heated. It will be possible.

Further, as shown in FIG. 2, the electric supply cord 6 is soldered to one end of each of the power supply lines 3.
The electric supply cord 6 supplies electric power to each heating element 2 when connected to an AC power source.

Next, the heating element 2 will be described. As shown in FIG. 4, the heating element 2 has a cylindrical shape, for example, an outer peripheral surface diameter of 4.0 mm, an axial length of 7.0 mm, and an inner peripheral surface of 1.0 m.
Since the shape of the heating element 2 is m and the inner and outer circumferential surfaces of the heating element 2 are coaxial with each other, the thickness in the radial direction is uniform. The inner peripheral surface electrode 7a and the outer peripheral surface electrode 7b are formed on the entire surface of the surface and the outer peripheral surface.
have.

These electrodes 7a and 7b are formed by applying a silver paste (made by Degussa Co.) for forming an ohmic contact electrode to the respective surfaces of the heating element 2 and then applying the heating element 2 thereto.
Obtained by heating at 560 ° C. for 5 minutes.

One of the power supply lines 3 is passed through the through hole forming the inner peripheral surface of the heating element 2 while being in contact with the inner peripheral surface electrode 7a of the heating element 2, and the other is supplied. By bringing the electric wire 3 into contact with the outer peripheral surface electrode 7b of the heating element 2, the both are electrically connected. At this time, each power supply line 3 may be fixed to each contact portion of the heating element 2 with a conductive adhesive. As a result, the power supply from each power supply line 3 to the heating element 2 can be made more reliable.

Since the heating element 2 is sandwiched by the electrodes 7a and 7b in the radial direction, it conducts volume conduction in which a current flows uniformly over the entire volume of the heating element 2 in the radial thickness. It is designed to generate heat evenly. Further, since the heating element 2 has a cylindrical shape, the area of each of the electrodes 7a and 7b can be made larger than before,
The resistance value of the heating element 2 can be reduced. As a result, the temperature of the heating element 2 can be raised quickly, and the object to be heated can be efficiently heated.

Next, a method of enclosing the heating unit 10 in the heater body 1 will be described.

As shown in FIG. 5, the heating unit 10 having each heating element 2 is enclosed in the heater body 1 when the heater body 1 is formed into a cord shape by extrusion molding. In this extrusion molding step, the thermoplastic resin 4 ′ is extruded from each nozzle 8 along both surfaces of each heating element 2 with a constant extrusion pressure, and covers the heat generating unit 10, thereby making the thermoplastic resin 4 ′. The heater body 1 in which the heat generating unit 10 is enclosed in the covering member 4 made of is formed.

In this way, the heating unit 10 including the heating elements 2 and the power supply lines 3 is covered by the covering member 4.
It is sealed in the heater body 1 and electrically insulated from the outside.

As described above, in the above method, since the heat generating unit 10 can be continuously sealed in the heater body 1 by extrusion molding of the thermoplastic resin 4 ', the heat generating unit 10 having no particular limitation in length is sealed. The heater body 1 can be easily manufactured. For example, the heater body 1 can be easily set to have a length of 100 m or more.

During the extrusion molding, the heating element 2 is used.
The covering member 4 is formed to have a uniform thickness in the radial direction. That is, the heater body 1 is formed to have a circular cross section. In this case, the heat conduction from the heating element 2 is evenly performed in the radial direction, and as a result, the heat is uniformly emitted onto the surface of the heater body 1.

By the way, conventionally, as shown in FIG. 9, after accurately aligning each heat generating element 52 with respect to each power supply line 53, a pair of electrode surfaces formed on the heat generating element 52 are respectively supplied with solder 55. They were connected and fixed to the electric wire 53, respectively. For this reason, if the above alignment process is inaccurate, the connection of each electrode surface by the solder 55 becomes defective, and good power supply cannot be obtained, and the heat generation of the heating element 52 may be impaired.

However, when the respective electrodes 7a and 7b of the heating element 2 shown in FIG. 4 are connected to the respective power supply lines 3, both of them can be connected at an arbitrary contact portion, so that the power supply line 3 can be connected. Since the accurate alignment between the heat generating element 2 and the heat generating element 2 is not required, and the solder can be omitted for the connection between the both, the efficiency of the assembling work is greatly improved as compared with the related art.

When the heating element 2 is in the shape of a rectangular parallelepiped, it is hard and brittle because the heating element 2 is made of ceramics, and the four corners are extruded when the heating elements 2 are encapsulated in the heater body 1. Occasionally, defective defects were generated in the corners. However, in the present invention, since the shape of the heating element 2 is a cylindrical shape, an unexpected impact from the outside is alleviated, and defective defects can be reduced.

The heating element 2 is a positive temperature coefficient thermistor P.
It is made of a ceramic having TC (Positive Temperature Coefficient) characteristics, for example, a ceramic semiconductor whose main raw material is barium titanate, and has a low resistance from room temperature to the Curie temperature Tc (rapid change temperature), but when it exceeds the Curie temperature Tc. It is a heat-sensitive element having a characteristic that the resistance value sharply increases.

Due to the above characteristics, when a voltage is applied to the heat generating element 2 at a low temperature below the Curie temperature Tc, a large current flows because the resistance value is small at first due to the low temperature, resulting in a rapid The temperature rises. On the other hand, when the temperature exceeds the Curie temperature Tc, the resistance value sharply increases,
As the flowing current value decreases and the amount of heat generation decreases,
The temperature does not rise above a certain temperature, and the temperature is kept stable. That is, the heating element 2 has a self-temperature control function. For this reason, the heating element 2 can omit the temperature control circuit and the overheat prevention circuit, can be downsized, and has no fear of ignition due to local overheating.

The Curie temperature Tc of the heating element 2 can be arbitrarily set within the range of -15 to 250 ° C. depending on the material composition, depending on the distance between the heating elements 2 and the thickness of the heater body 1. However, in this embodiment, the Curie temperature Tc of the heating element 2 is set to 40 ° C. to 50 ° C., and the Curie temperature Tc is set to have a positive temperature characteristic in a temperature range from a predetermined temperature to the maximum heating temperature of the heating element 2. It is set. Further, the heating elements 2 are arranged in the heater body 1 at an equal interval of 20 pieces per 1 m, and when the outside air temperature is -20 ° C., a commercial voltage of 100 V alternating current is applied to the unit. The total power consumption of each heating element 2 is about 18W per 1m length
Is set to be

As described above, in the heater body 1, the resistance values of the individual heating elements 2 arranged at the predetermined intervals rapidly increase (or decrease) in accordance with the temperature of the outside air. That is, in an area where the outside air temperature around the water pipe is lower than room temperature, for example, below the freezing point temperature, the resistance value of the heating element 2 located in that area becomes small, current easily flows, and the water pipe is heated. , Freezing of water inside the water pipe is prevented.

On the other hand, in a portion where the outside air temperature around the water pipe is high, the resistance value of the heating element 2 located in that portion is increased, the flowing current is reduced and the calorific value is reduced, and a constant temperature is maintained and heat is generated. The power consumption of the body 2 can be reduced.

In the above method, the heating element 2 is connected to each power supply line 3
While pulling out the heat generating unit 10 connected to each, by the thermoplastic resin 4 ′ melted at the time of extrusion molding,
The heating unit 10 is enclosed in the heater body 1.

From this, since the heat generating unit 10 is pulled out by the above method, tension is generated in each of the power supply lines 3, so that each of the power supply lines 3 is parallel to each other and is maintained at a predetermined interval. Heater body 1 while maintaining insulation
Since it can be enclosed inside, the production of the heat generating unit 10 in which the heat generating element 2 is connected to each power supply line 3 can be easily automated.

The power supply line 3 is connected to the outer peripheral surface electrode 7 of the heating element 2.
When connecting to b, connect with a conductive adhesive as described above,
Not only to fix, but also solder 1 as shown in FIG.
It is also possible to use 1.

In this way, the heating element 2 and the power supply line 3 are connected by a conductive adhesive, and the outer peripheral surface of each heating element 2 and the power supply line 3 are connected.
The connection strength between the power supply line 3 and the heating element 2 can be further improved by fixing with solder at the connection point with.

From this, a stronger connection strength against the stress generated by the bending of the power supply line 3 when the heater body 1 is spirally wound around the water pipe or pressure-bonded along the length direction of the water pipe is obtained. Can be exhibited, and a structure that is stronger against bending can be obtained. As a result, the heating element 2
Since it is possible to further prevent the connection portion between the power supply line 3 and the power supply line 3 from being disconnected, and since the heating element 2 and the power supply line 3 are electrically and more reliably connected, it is possible to efficiently heat the water pipe. It becomes possible to perform it more reliably.

[Embodiment 2] Another embodiment of the present invention will be described below as Embodiment 2 with reference to FIGS. In addition, the same member numbers are given to the respective members having the same functions as those in the first embodiment, and the description thereof will be omitted. As shown in FIG. 7, the heater of this embodiment has a heating element 2, electrodes 7a,
The heat generating unit 13 constituted by 7b and the power supply line 3 is formed in the same manner as in the first embodiment, but the covering member 40 as a material of the heater body 12 does not cover the heat generating unit 13 over the entire surface. , The heating unit 1
3 is formed so as to be held.

In this case, an adhesive tape or an adhesive material (not shown) is provided on the back side of the power supply line 3. The power supply line 3 and the heater body 12 are fixed to each other by the adhesive tape or the adhesive material, and the heat generating unit 13 is held in the heater body 12 in a stable form.

In the structure of this embodiment, since the heat generating unit 13 is provided on only one surface of the heater body 12, the resin surface opposite to the heat generating unit 13 of the heater body 12 is formed. The resin surface can be spirally wound around the outer peripheral surface of the water pipe so as to be along the axial direction of the water pipe. When the heater main body 12 used in this manner is covered with glass wool or insulating tape from above, the convex portions are concentrated on only one surface, so that the heating unit 13
As compared with the case where the entire surface of the heater is covered with the covering member 40, the heater body 12 is easily bent.

Therefore, the heater body 12 of the present embodiment.
Even if it is a water pipe having a large curvature, that is, a small diameter, it can be spirally wound around the outer peripheral surface of the water pipe along its axial direction without difficulty. Further, instead of spirally winding the water pipe as described above, the water pipe may be coated so as to be crimped to the water pipe along the length direction of the water pipe.

Further, one surface of the heating element 2 is not covered with the covering member 40. As a result, the heating element 2 more quickly responds to changes in the outside air temperature and changes its resistance value faster. Therefore, the water pipe can be quickly heated, and the freezing of water in the water pipe can be prevented.

The above-mentioned embodiments do not limit the present invention, and various modifications can be made within the scope of the invention. For example, although an example in which a vinyl chloride resin is used as the material of the covering member 4 described in the above examples is given, the present invention is not limited to this, and melting or deformation due to the heat generation temperature of the heating element 2 does not occur, and the above It is possible to use a resin material or a rubber material whose physical properties change little even if the heating by the heating element 2 and the cooling by the outside air temperature below the freezing point temperature are repeated.

Examples of the rubber material of the covering members 4 and 40 include butyl rubber, natural rubber, butadiene rubber, ethylene-propylene rubber, chloroprene rubber, isoprene rubber, styrene-butadiene rubber, acrylic rubber, chlorosulfonated rubber, and silicone. Examples thereof include rubber, fluorosilicone rubber, fluororesin rubber and the like.

Examples of resin materials for the covering members 4 and 40 include polyolefin resins such as polyethylene and polypropylene, polyurethane resins, poly-4-methylpentene-1, silicone resins, fluororesins,
Examples thereof include polycarbonate resin, polyamide resin, polyphenylene oxide resin, polybutylene terephthalate, polyethylene terephthalate, and polyimide resin.

The construction of each of the above-mentioned embodiments can be applied to any water pipe, but in particular, a water pipe made of casting such as iron used in the cold regions of southern Tohoku and Shinshu. Most preferably used for.

This is because the water pipe is also used to cause the water pipe itself to generate heat by flowing a high current when the water therein freezes, and to melt the frozen water by heat generation. Therefore, since it has a large thermal conductivity, the heat from the heater bodies 1 and 12 of each of the above-described embodiments, which makes line contact, is efficiently transmitted to the entire water pipe.

In the configuration of the above-mentioned embodiment, an example in which a water pipe, which is a water retention site, is used as the object to be heated by the heater of the present invention has been described, but the invention is not particularly limited to this. Used by adhering to the outer surface of the pump, sprinkler, water tank, drainage port, U-shaped water sealing part of the drainage pipe, etc. directly in the ground, directly putting it in water, under the side of the track or the surface of the road It is also possible to embed it in and use it. By burying the heater below the center line of the road and using it, it is possible to improve the visibility of the center line during snowfall.

Further, in the above description, one power supply line 3 is connected to the outer peripheral surface electrode 7b of each heating element 2, and the other power supply line 3 is connected to the inner peripheral surface electrode 7a of each heating element 2. Although the method has been described, the method is not particularly limited to this, and as another method of connecting the heating elements 2 and the power supply lines 3, as shown in FIG. A method of alternately connecting the inner peripheral surface electrode 7a and the outer peripheral surface electrode 7b of the body 2 can be mentioned.

In this method, the thickness of the outer peripheral surface of the heater body 21 and the surface of the heater body 21 in the heater body 21 when coating each feeder 3 and each heater 2 with a thermoplastic resin is larger than that in the above embodiment. The heater body 21 can be formed so as to be even and thin, and as a result, the thickness of the covering member 41 can be reduced, and the heating efficiency of each heating element 2 is improved.

[0051]

According to the heater of the present invention, a heating element is formed in a tubular shape and is provided in the main body, and a pair of power supply lines for energizing the heating element is provided in the main body, and each of the above-mentioned supply lines is provided. In this configuration, electrodes connected to the electric wires are formed on the inner peripheral surface and the outer peripheral surface of the heating element, respectively.

Therefore, in the above structure, each electrode is provided on the outer peripheral surface and the inner peripheral surface of the cylindrical heating element, and
Connect one power supply line through the electrode on the inner peripheral surface of the heating element,
The other power supply line is connected to an electrode on an arbitrary outer peripheral surface of the heating element. Therefore, the alignment for connecting the power supply line and the electrodes of each heating element becomes easier than before.

As a result, in the above-mentioned structure, the time-consuming process of accurately aligning the heating element and the power supply line, which has been conventionally required, can be omitted, so that the manufacturing process can be simplified.

[Brief description of drawings]

FIG. 1 is a fragmentary perspective view of a heater according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the heater.

3 is a cross-sectional view taken along the line I-I of the heater shown in FIG.

FIG. 4 is a perspective view showing a shape of a heating element and electrodes in the heater.

FIG. 5 is an explanatory diagram of extrusion molding of the heater.

FIG. 6 is an explanatory diagram showing a state where the heater is soldered.

FIG. 7 is an explanatory diagram showing a second embodiment of the heater of the present invention.

FIG. 8 is a fragmentary perspective view of a modified example showing a connection position between a heating element and a power supply line in the heater.

FIG. 9 is an explanatory diagram of a conventional heater.

FIG. 10 is an explanatory diagram of extrusion molding of the heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heater main body 2 Heating element 3 Feed line 4 Covering member 6 Electric supply cord 7a Inner peripheral surface electrode 7b Outer peripheral surface electrode

Claims (1)

[Claims] 1. A main body having electrical insulation and flexibility is provided in a cord shape by extrusion molding of synthetic resin, and a plurality of heating elements formed in a cylindrical shape of ceramics which is a positive temperature coefficient thermistor are provided on the main body. A pair of power supply lines provided along the length direction of the main body for supplying power to each heating element is provided in the main body, and each electrode connected to each power supply line is A heater formed on a peripheral surface and an outer peripheral surface so as to extend along a circumferential direction.