JPH0465511B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flexible heating wire used as a heater for electric blankets, electric carpets, etc., and as a wire for preventing excessive temperature rise.

Conventional Structure and Problems Conventionally, flexible heating wires used for electric carpets, electric blankets, etc. have a first conductor wire 1 and a second conductor wire 2 arranged in concentric circles, as shown in Fig. 1. Both conductor wires were short-circuited and excessive temperature rise was detected by utilizing the sharp melting behavior at the melting point of the nylon resin 3, which was provided spirally in the form of a winding and an outer winding, and was interposed therebetween. However, in this structure, the winding process with low productivity must be performed twice, inner winding and outer winding, and there is a limit to productivity and cost.

On the other hand, conventional heating wires with a positive temperature coefficient of resistance (hereinafter referred to as PTC heating wires) are shown in Figures 1 and 2, for example.
It was constructed as shown in the figure. In FIGS. 1 and 2, 3 is a PTC heating layer, and in FIG.
The second conductor wires 2, 2' are spirally wound, and the outer surface thereof is tubed with an insulator 5. Further, a core yarn 4 is arranged on the inner surface of the PTC heat generating layer 3. In this configuration, the PTC heating layer 3
A certain self-control temperature can be set using the PTC curve of the PTC heating layer 3, but due to external pressure, bending, twisting, etc., the distance between the electrodes may become locally small, or a part of the PTC heating layer 3 may become conductive. If a chemical substance is accidentally mixed in, the resistance value of the entire heating wire remains almost unchanged, and current concentrates in that part, causing local overheating, arcing, and even shortening between the electrodes, which can lead to safety hazards such as burns and fires. It had the potential to damage the Regarding the short between the first and second conductor wires 1 and 2, there is a large change in the current value flowing through the entire heating wire, so it is possible to easily stop the current flow with a current fuse etc., although it is dangerous. The resistance value of the entire heating wire hardly changes, and even if it changes, it is within the self-control resistance value range of the PTC heating wire itself, and safety cannot be ensured if the current is concentrated in that part. It was hot.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
The aim is to provide safe and reliable products.

Structure of the Invention The present invention is characterized in that a first conductor wire 1a and a second conductor wire 2a are spirally formed in parallel on a heat-shrinkable core yarn 4a as shown in FIG. do. The heat-shrinkable core yarn 4a is an insulating fiber that undergoes a large heat shrinkage at the operating temperature of the temperature rise prevention device, that is, at a temperature of 120 to 200°C. Specifically, organic fibers such as polyester, polyamide, and polyvinyl alcohol copolymer (vinyl alcohol copolymer) are suitable, and this property is particularly noticeable in drawn yarns. In addition, since the flexible heating wire of the present invention is manufactured with some tension applied during the wire manufacturing process, the core yarn 4
When stretched by the tension of a, it becomes a flexible heating wire. Therefore, the heat-shrinkable core thread 4a in the present invention is not only a heat-shrinkable thread but also a thread with a diameter of 0 to 5
It also includes threads with high elongation due to a tension of about Kg. In other words, this thread becomes an electric wire in a stretched state during the wire making process, and when the temperature rises to an excessively high temperature of 120 to 200 degrees Celsius, stress is applied due to the softening of the outer sheath 5, causing it to shrink as an electric wire. produce results. Therefore, the heat-setting treatment generally performed on the core yarn is a process of adjusting the ratio of elongation to heat shrinkability, and the heat shrinkability in the present invention is proportional to the sum of the elongation and heat shrinkage rate. That is, the flexible heating wire in the present invention shrinks significantly, for example, by 8% or more when the temperature rises abnormally, causing a short circuit between the two conductor wires 1a and 2a. The shrinkage rate at this time is approximately the sum of the heat shrinkage rate of the core yarn itself and the elongation during production of the heating wire.

The following two types of PTC heat generating layers 3 are used in the present invention. That is, (A) first conductor wire 1
a. In the case of a heating wire in which one of the second conductor wires 2a is used as a heating wire and the other is used as a signal wire, the PTC heating layer 3 is not necessarily required, but a heat-melting layer such as nylon 11 or 12 is A molecular layer may also be provided. In this case, when the temperature rises abnormally, this layer 3 melts and changes into a low viscosity liquid, so that the safety operation of the present invention can be operated very stably.

(B) A PTC heating layer having a large positive temperature coefficient of resistance may be provided in the PTC heating layer 3, and in this case, the flexible heating wire of the present invention acts to prevent excessive temperature rise.
It becomes a PTC heating wire.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Example 1 A copper wire with a diameter of 0.17 mm is placed on a 1500 denier heat-shrinkable core yarn 4a made of stretched nylon 6.
Foil was produced to a thickness of 0.06 mm, and two pieces were wound in parallel with a pitch of 1.2 mm to form the first and second conductor wires 1a and 2a. A 0.5 m thick layer of a soft polyvinyl chloride composition was coated thereon as an insulating jacket 5. This was designated as sample [A]. Separately, as sample [B], PTC made of nylon 12 as shown in Figure 3.
After forming the heat generating layer 3, it was covered with an insulating jacket 5 similar to that of sample [A]. Set these samples [A, B] in the furnace and apply 0.8A to the conductor wire 1a.
When the temperature of the furnace was raised at a heating rate of 1°C/min, the first and second conductor wires 1
a and 2a are short-circuited at 176℃ in sample [A] and 169℃ in sample [B], blowing the fuse,
A safe operation was performed to cut off the power. Compared to sample [A], [B] had less variation in operating temperature and was more stable in operation.

Example 2 First and second copper conductor wires 1a and 2a are wound around a 1500 denier drawn polyester core thread 1a according to the same specifications as in Example 1, and carbon black is used as the PTC heat generating layer 3. 20% polyethylene-vinyl acetate copolymer 30%, polyethylene 50%
A flexible heating wire as shown in FIG. 3 was constructed by covering the wire with a material consisting of Set this in a furnace and heat it at 1℃/
When the temperature was raised to 172° C., a short circuit occurred between the first and second conductor wires 1a and 2a, the fuse was blown, and the current was cut off, resulting in a safe operation.

In this way, sufficient safety can be ensured even against localized abnormal overheating. That is, the first,
The distance between the second conductor wires 1a and 2a becomes smaller,
If a conductive substance is mixed into the PTC heating layer 3, or if the first and second conductor wires 1a and 2a
When local overheating occurs due to breakage or almost breakage, the core thread 4a is heat-shrinked, the first and second conductor wires 1a and 2a are brought into contact and short-circuited, and the first and second conductor wires are short-circuited. 1a and 2a are used as sheets to melt a current fuse and cut off current to detect abnormal overheating or local overheating. This flexible heating wire has a simple configuration as shown in Figure 3.
It has PTC characteristics and overheat fusing function.
It becomes a highly safe and highly functional flexible heating wire.

In addition, the heat-shrinkable core yarn 4a has a temperature of 8 at 120℃ to 200℃.
% or more, 120°C to 200°C,
It shows the safe operating temperature when the temperature rises abnormally, and a shrinkage rate of 8% or more shows the shrinkage limit for reliable safe operation. Moreover, here, the reason why the melting point of the core thread 4a is 200° C. or less is based on the following reason. That is, when installed in a fabric electric heating device, if the temperature rises above 200°C, it will ignite and emit smoke, causing an accident. Therefore,
It is important for product safety to have an overrise prevention temperature of 200℃ or less. The PTC heating layer 3 is a polymer composition containing a particulate conductive agent mainly composed of carbon black, and examples of resins used therein include polyethylene-vinyl acetate copolymer, polyethylene-ethyl acrylate copolymer, There are crystalline resins such as polyolefins such as polyethylene and polypropylene, polyamides, and polyesters, which exhibit a sharp positive temperature coefficient near the crystal transformation point of 60 to 180°C.

The distance between the first and second conductor wires 1a and 2a is 0.3~
The PTC heating layer 3 may be made of a composition having a high specific resistance, and PTC characteristics for self-temperature control can be easily obtained.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

The distance between the first and second conductor wires may become smaller locally due to external pressure, bending, twisting, etc.
If a conductive substance is mixed into the PTC heating layer,
If the first and second conductor wires themselves are disconnected or nearly disconnected, or if they are heated abnormally due to external factors, local overheating, abnormal overheating, or overheating due to arcing occurs, and the core yarn shrinks. However, the first and second conductor wires are short-circuited, the current fuse is blown, and the current supply is stopped, thereby improving safety.

[Brief explanation of the drawing]

1 and 2 are a side view and a perspective view showing a conventional example, and FIG. 3 is a side view showing an embodiment of the present invention. 1a, 2a...first and second conductor wires, 3...
PTC heating layer, 4a... core wire.

Claims (1)

[Claims] 1. A first conductor wire and a second conductor wire are spirally wound in parallel on a core yarn, and when the temperature rises abnormally, the first conductor wire and the second conductor wire are Said second
Flexible heating wire that short-circuits conductor wires. 2. The flexible heating wire according to claim 1, wherein the core yarn shrinks by 8% or more when the temperature rises abnormally. 3. The flexible heating wire according to claim 1 or 2, wherein the core yarn is one selected from polyester, polyamide, and polyvinyl alcohol copolymers. 4. The flexible heating wire according to claim 1 or 2, wherein one of the first and second conductor wires is a heating element wire and the other is a signal wire. 5. Forming a PTC heating layer on the first and second conductor wires formed in a spiral shape using a composition having a large positive temperature coefficient of resistance (hereinafter abbreviated as PTC) at a temperature lower than the heat shrinkage temperature of the core yarn, Further, a third conductor wire is formed in a spiral shape on the outside thereof, and one of the first and second conductor wires and the third conductor wire are used as electrodes of the PTC heating layer. Flexible heating wire. 6. The flexible heating wire according to claim 5, wherein the PTC heating layer is made of a polyolefin composition containing carbon black.