JPH0554896B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a new detection body used for detecting localized temperatures above the surface of a surface heating element or the floor of a building, etc. The purpose is to prevent the occurrence of

[Conventional technology]

Conventional abnormal temperature detection technology uses two opposing
By laying a meandering detection wire in a fixed pattern between the two electrodes, or installing a surface detection device such as a plastic thermistor, changes in resistance and capacitance of the detection layer due to changes in ambient temperature can be captured through the electrodes. A type of temperature fuse method in which a detection wire with an insulator interposed between two electrodes is arranged in a meandering manner, and when an abnormal temperature rise occurs, the insulator melts and the electrode becomes conductive to detect an abnormality. There is something like that. However, the former method measures the resistance and capacitance over the entire length of the detection wire or the entire surface of the planar detector, and has the disadvantage that it cannot detect localized abnormal temperatures on the surface, and the latter method is unreliable. The drawback is that it is not sufficient and cannot perform detailed detection across the entire surface. Furthermore, a method has been used in which ceramic thermistors are installed in required areas, but this method has the disadvantage that detection is limited to only certain areas.

[Problem that the invention seeks to solve]

None of the conventional abnormal temperature detection techniques described above can reliably detect when a local abnormal temperature occurs in an unspecified portion over a wide range of a surface. The present invention has been made to solve this problem, and in the case of a surface heating element, the detection body according to the present invention is provided closely together,
On the floor, it is installed under a rug to detect local abnormal temperatures and prevent a fire from occurring at the local burnout stage.

[Means for solving problems]

FIG. 1 is a cross-sectional view showing the structure of a local abnormal temperature detector according to the present invention. In the figure, 1 is a heat-sensitive expandable base material layer made of a semiconductive to conductive plastic sheet, which is made of polyolefin homopolymers, copolymers, polyesters, plastics such as soft PVC, various elastomers, etc., and is coated with metals. Contains conductive powder such as powder, graphite powder, carbon black, etc., and also contains metal salt,
It is a film or sheet-like product made by adding and mixing metal oxides, metal hydrates, organic blowing agents, etc. This base material layer preferably has a volume resistivity of 10 ³ Ω・cm or less, and at a certain temperature, for example, 200°C or higher, the volume of the base material layer increases by 100% or more due to gases generated from the compounding agents. It shows the expansion rate. 2 is an insulating layer with a large number of through holes 3 layered on the base material layer 1, and is an insulating film, sheet, or coarse insulating film made of plastic, paper, or other material with a large number of fine holes drilled all over the surface. Non-woven films, sheets, coarse woven fabrics made of fibers, and other films and sheets having a large number of voids substantially in the thickness direction are applicable. 4 is a heat-sensitive expandable base material layer 1 and a porous insulating layer 2
A metal foil layer that serves as an electrode is arranged to sandwich the metal foil.Although metal foil may be used alone, it is also possible to use plastic film, nonwoven fabric, paper, etc. as a base and laminated with metal foil, vacuum evaporation, sputtering. It is also possible to use a metal layer formed with a thickness of several μm to several tens of μm by plating or the like, or coated with a conductive paint. Reference numeral 5 denotes an insulating protective layer formed as the outermost layer if necessary, and various plastics and elastomers are used.

[Action and effect of the invention]

In the local abnormal temperature detector according to the present invention configured as described above, the heat-sensitive expandable base layer 1 and the metal foil layer 4, which is one electrode, are insulated by the perforated insulating layer 2 during normal operation. . When a localized abnormal temperature rise is sensed from the outside, the expandable base layer 1 in that area softens and melts, begins to expand in volume, and enters the through holes 3 of the insulating layer 2, and as this progresses, One metal foil layer 4 that was finally insulated
The two electrodes 4, 4 are in contact with each other through the expansion layer of the corresponding portion, as shown in the second figure. Therefore, by connecting the lead wires taken out from these two electrodes 4, 4 to an alarm device such as a lamp or a buzzer to form a closed circuit, abnormal conditions can be detected immediately and an alarm can be issued.

As explained above, the detection body according to the present invention has the effect of being able to reliably detect abnormal temperatures occurring in unspecified local areas on a wide surface. In addition, in implementation,
Manufacture a long film or sheet-like detector with a cross section as shown in Figure 1 and an appropriate width, cut it to the required length, or lay it out in an appropriate number of strips to adapt it to the area you want to detect. can do.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing the structure of the detector according to the present invention, with FIG. 1 showing a normal state, and FIG. 2 showing a state for detecting local abnormal temperature, etc. 1... Heat-sensitive expandable base material layer, 2... Insulating layer, 3...
...Through hole, 4... Electrode, 5... Insulating protective layer.

Claims (1)

[Claims] 1 The two metal foil layers are insulated by a heat-sensitive expandable base layer made of a semiconductive or conductive plastic sheet that is in contact with the metal foil layers, and an insulating layer with a large number of through holes. The local abnormal temperature sensing body is characterized in that the two metal foil layers are electrically connected to each other through the through holes in the insulating layer by softening and melting the expandable base layer when sensing heat.