JP2002334766A - Heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem of the conventional sheet heating element being not capable of detecting abnormal overheat. SOLUTION: This heating device is composed of a heating element 11; a melting body 12 which is installed inside the heating element 11 and melts at the specified temperature; an electric conductor 13 installed inside the melting body 12; and a resistance detecting means 14 for detecting a resistance value of the heating element 11. The resistance value variation of the heating element 11 is detected with the resistance detecting means 14 to detect abnormal heating. Therefore, the installation of an extra temperature sensor is not required, and the abnormal overheat can be detected by simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device.

[0002]

2. Description of the Related Art Conventionally, as a heating device having a positive temperature resistance coefficient, as shown in FIG. 4, a first electrode 1, a second electrode 2, and a positive temperature resistance coefficient provided between the electrodes are used. And the sheet heating element 3 has a self-temperature control function.

[0003]

However, in the conventional heating apparatus, there is no safety mechanism when the heating element is deteriorated or the like, and there is a risk of abnormal overheating or burning. Therefore, it is necessary to limit the use to products without danger of burning, or to separately provide a temperature sensor to detect an abnormal temperature, which has a complicated configuration.

[0004]

In order to solve the above-mentioned problems, the present invention provides a heating element, a melt provided in the heating element and melting at a predetermined temperature, and a conductor provided in the melt. And a heating element provided with resistance detecting means for detecting a resistance value of the heating element.

[0005] According to the above invention, a melt having a conductor and melting at a predetermined temperature is provided in the heating element, and the resistance of the heating element is detected by the resistance detecting means, so that the molten state of the melt is detected. Detection can detect abnormal overheating of the heating element. That is, when the heating element abnormally generates heat, the melt is melted, and the conductor provided in the melt is diffused into the heating element, whereby a decrease in the resistance value of the heating element is detected by the resistance detection unit.

As a result, abnormal heating of the heating element can be detected. Further, the abnormality detection temperature can be adjusted by selecting the material of the melt. As a result, it is not necessary to newly provide a temperature sensor, and abnormal overheating can be detected with a simple configuration.

[0007]

The invention according to claim 1 is characterized in that a heating element, a melt provided in the heating element and melted at a predetermined temperature, a conductor provided in the melt, and a resistance value of the heating element This is a heating element provided with a resistance detecting means for detecting the temperature. According to this, a melt having a conductor and melting at a predetermined temperature is provided in the heating element, and the resistance of the heating element is detected by the resistance detection means, thereby detecting the melting state of the melt and detecting the heating element. Abnormal overheating can be detected. That is, when the heating element abnormally generates heat, the melt is melted, and the conductor provided in the melt is diffused into the heating element, whereby a decrease in the resistance value of the heating element is detected by the resistance detection unit.

As a result, abnormal heating of the heating element can be detected. Further, the abnormality detection temperature can be adjusted by selecting the material of the melt. As a result, it is not necessary to newly provide a temperature sensor, and abnormal overheating can be detected with a simple configuration.

According to a second aspect of the present invention, there is provided a heating device in which the heating element has a positive temperature coefficient. Since the heating element has a positive temperature coefficient, if the heater generates abnormal heat, the conductor in the melt diffuses and the resistance value of the heating element decreases. improves. According to the second aspect of the present invention, since the heating element has a positive temperature coefficient, when abnormal heating occurs, the conductor in the melt diffuses and the resistance value of the heating element decreases, so that the temperature of the heating element also decreases. And reliability is improved.

According to a third aspect of the present invention, there is provided a heating device provided with a safety device for determining that the output of the resistance detecting means is out of a predetermined value range, determining that the overheating is abnormal, and cutting off the power supply to the heating element.

[0011] By providing a safety device for judging an abnormality based on the output result of the resistance detecting means and cutting off the power supply to the heating element, the safety as a device is improved.

According to the fourth aspect of the present invention, since the insulating layer is made of the polyamide composition, the molding is easy, the reliability is excellent, and the cost is low.

According to the fifth aspect of the present invention, since it is made of polyethylene or a polyethylene composition, it is easy to mold, has high reliability, and has low cost.

According to the sixth aspect of the present invention, since the conductor is made of carbon, it is inexpensive and has good diffusivity, so that accurate abnormality detection is possible.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of a heating apparatus according to Embodiment 1 of the present invention. Explaining the structure, a heating element 11 having a positive temperature resistance coefficient, a melt 12 formed in the heating element 11 and melting at a predetermined temperature, a conductor 13 provided in the melt, and a resistance of the heating element 11 A resistance detecting means 14 for detecting a value is provided. In this embodiment, the resistance detecting means 14 includes a first electrode 15 formed on one surface of the heating element 11 and a second electrode 16 formed on the other surface. A metal foil electrode having a thickness of about 35 μm was used as the first electrode 15 and the second electrode 16.

In the present embodiment, the heating element 1 having a positive temperature coefficient of resistance formed between the first electrode 15 and the second electrode 16 is used.
Sample No. 1 was formed from a kneaded sheet of a crystalline polymer having a carboxyl group introduced into the terminal of low-density polyethylene and an oil furnace carbon black. Further, a melt 12 that melts at a predetermined temperature was provided in the heating element 11, and a conductor 13 was formed inside the melt 12. As the melt 12, a polyamide composition was used. In this example, nylon-11 which melts at around 100 ° C. was used. The conductor 13 is a car.
Bon powder was used.

Further, resistance detecting means 14 for detecting a resistance value between the first electrode 15 and the second electrode 16 provided on the upper and lower surfaces of the heating element 11 is provided.

FIG. 2 shows the resistance detecting means 14 in this embodiment.
2 shows the relationship between the output result and the surface temperature of the heating element 11. In this embodiment, the heating element 11 that generates heat up to a high temperature is used assuming abnormal overheating. As shown in FIG. 2, the output result of the resistance detecting means 14 shows infinity in a normal temperature range, that is, 90 ° C. or lower, but it can be seen that the resistance sharply drops from around 100 ° C. This is because the melt 12 was melted by heat, and the conductor 13 in the melt 12 was diffused into the heating element 11. Therefore, by detecting the resistance value of the heating element 11, the surface temperature of the heating element 11 can be managed. Therefore, the planar heating element of this embodiment can detect abnormal overheating with a simple configuration, and can improve the safety and reliability of the planar heating element.

In this embodiment, a polyamide composition was used as the melt 13. However, similar effects were obtained by using polyethylene or its composition.

In this embodiment, the conductor 13 is a car.
Although the bon powder is used, the same effect can be obtained by using iron powder or the like. The same effect can be obtained by using not only powder but also a conductive solution for the conductor 13.

(Embodiment 2) FIG. 3 is a structural view of a planar heating element according to Embodiment 2 of the present invention. In the second embodiment, the first embodiment
The difference is that when the output of the resistance detecting means 14 is not within the predetermined value range, a safety device 17 is provided which determines that the overheating has occurred and shuts off the power supply to the heating element. In this embodiment, since the output of the resistance detecting means 14 is set to 10 kΩ or more, as shown in FIG. For this reason, the planar heating element of this configuration can prevent abnormal overheating and improve the safety as a device.

[0023]

As is apparent from the above embodiment, according to the present invention, a melt having a conductor and melting at a predetermined temperature is provided in the heating element, and the resistance of the heating element is detected by the resistance detecting means. By detecting, it is possible to detect the molten state of the melt and detect abnormal overheating of the heating element.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a sheet heating element according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a heating element temperature and an output result of a resistance detecting unit according to the present invention;

FIG. 3 is a sectional view of a sheet heating element according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional planar heating element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st electrode 2 2nd electrode 3 Heating element 11 Heating element 12 Melt 13 Conductor 14 Resistance detection means 15 First electrode 16 Second electrode 17 Safety device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K058 AA12 CA34 CA54 CA62 CA63 CA92 3K092 QB14 QB21 RF26 UA06 UA19 VV25

Claims (6)

[Claims] 1. A heating element, a melt provided in the heating element and melting at a predetermined temperature, a conductor provided in the melt, and resistance detecting means for detecting a resistance value of the heating element are provided. Heating equipment. 2. The heating device according to claim 1, wherein the heating element has a positive temperature coefficient. 3. The heating device according to claim 1, further comprising a safety device for judging an abnormal overheating when the output of the resistance detecting means is out of a predetermined value range and cutting off the power supply to the heating element. 4. The heating device according to claim 1, wherein the melt comprises a polyamide composition. 5. The heating device according to claim 1, wherein the melt is made of polyethylene or a polyethylene composition. 6. The heating device according to claim 1, wherein the conductor is made of carbon.