JPH0479479B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flexible heating wire having a large positive temperature coefficient of resistance (hereinafter abbreviated as PTC) for use in electric heating devices and the like.

Conventional configuration and its problems Conventionally, PTC heating wires have self-temperature control in which the temperature rises to a certain temperature by applying a constant voltage and does not rise above that temperature due to its large PTC characteristics. It was suitable as a heater for electric heating equipment. The most common structure is one in which a PTC layer is formed between a pair of parallel cable-shaped electrodes.

However, this PTC heating wire has low resistance at low temperatures due to its PTC characteristics, so the inrush power is extremely large when applied to large heating devices, and the power supply voltage is This had a large effect on the PTC heating wire, and was a major drawback of the PTC heating wire.

OBJECTS OF THE INVENTION The object of the present invention is to obtain a flexible heating wire whose main component is a PTC heating element, which limits the conventional inrush current at low temperatures and reduces the influence on the power supply voltage.

Structure of the Invention The present invention is constructed by disposing a heating element having a large positive temperature coefficient of resistance between at least one pair of electrodes in which a metal conductor wire is attached to a flexible core thread, and covering the electrode with an insulating jacket. In the flexible heating wire, the metal conductor wire is made of a copper alloy wire and the surface is made of a high-resistance metal oxide material so as to be in direct contact with the heating element, or the surface of the metal conductor electrode is made of an organic metal chelate. A high-resistance element is provided to control the thickness of the coating layer and to generate conduction such as tunnel conduction or hopping conduction.

Description of Examples The present invention makes the surface of a metal conductor wire, which is an electrode of a PTC heating wire, have a high resistance, and directly connects the high resistance layer to a high resistance layer.
It contacts the PCT heating wire and limits inrush current when the PTC heating element is at low temperature. PTC heating wires have PTC layers arranged in parallel in the length direction between a pair of electrodes, so the high resistance layer on the electrode surface is
It will be connected in series with the layers. Therefore, PTC
The inrush current when the layer is at a low temperature can be limited by the resistance of this high resistance layer. As the metal conductor wire used in the present invention, a metal with high electrical conductivity is suitable, and a copper alloy wire is practical. As a method for increasing the resistance of the surface of a copper alloy wire, the surface can be coated with a metal oxide, a high-resistance metal, etc. to make it a semiconductor and increase the resistance. Furthermore, as a method for increasing the resistance of the surface of a metal conductor electrode, a resistance layer can be formed on the metal surface by utilizing an organic metal chelate bond. In this case, if the organic portion is an insulating structural molecule, it is necessary to control the thickness of the coating layer and create a state in which conduction such as tunneling conduction or hopping conduction occurs to increase the resistance. On the other hand, if the organic portion is a molecular layer having a conductive channel having an organic semiconductor structure, the film thickness is not limited to this. Metal chelates can be formed from metal titanates, silane coupling agents, carboxylic acids, hydroxyl groups, and the like.

In the present invention, such a high resistance layer is formed.
The PTC heating wire will be explained based on an example.

FIG. 1 shows a partially cutaway side view of the flexible heating wire of the present invention.

In the figure, 1 is core thread, 2 is copper foil, 3 is PTC
4 indicates a heat generating layer and an outer cover.

The structure of the flexible heating wire of the present invention will be explained.

2000 denier polyester core thread 1 with tinned copper foil 2 (foil width 0.55mm, foil thickness 0.08mm) at a pitch of 0.9mm
It was formed into a spiral shape. This wire can be divided into two parts to form two electrode wires, and each can be subjected to the following two high-resistance treatments (A) and (B).

(A) The core yarn with copper foil was oxidized in a 120° C. furnace to form a Cu ₂ O layer. The film thickness was about 5μ.

(B) The core yarn with copper foil was repeatedly dipped into the silane coupling agent to form a film thickness of about 50 mμ.

Using either of the high-resistance electrode-attached core threads treated in (A) or (B) above, a PTC with a structure as shown in Figure 1 is produced.
A heating wire was constructed. Spiral electrode spacing is 0.9mm
It was hot. The outer jacket 4 was coated with a soft polyvinyl chloride composition. PTC heating wire 3 is carbon black 21
% polyethylene-vinyl acetate copolymer was used. After thermally annealing the PTC heating wires obtained in this way at 120℃ for 10 hours, these
When we measured the resistance-temperature characteristics of the PTC heating wire, we found that
Compared to curve C of the conventional example using (A) treated and (B) treated copper foil electrodes and copper foil electrodes as they are, as shown in Figure 2, the resistance value is relatively high on the low temperature side, that is, the inrush current An excellent exothermic wire of the present invention with limited heat generation was obtained. Incidentally, the equivalent circuit of the high resistance layer 5 in the present invention is expressed as shown in FIG. Here, the variable resistance 6 due to heat is the resistance of the PTC layer. Note that the resistance inside the electrode conductor wire is much lower than the high-resistance layer on the surface, so the equivalent circuit is ignored here, but when using a long wire such as 20 m to 50 m,
Of course, it cannot be ignored.

When we wired two approximately 40m long PTC heating wires A into a 2-tatami carpet, the inrush power at 10°C was 1.13KW at 100V. Traditional PTC
In a similar experiment with a heating wire, the inrush power was 2.5KW, which was too large.

Effects of the Invention The present invention limits inrush current by increasing the resistance of the surface of a metal conductor electrode wire.
For high-capacity heating equipment products that are wired with PTC heating wires, the effect on the power supply voltage can be significantly reduced.
In addition, since a high resistance layer on the surface of the metal conductor electrode wire is present in every part of the PTC heating layer arranged in parallel in the longitudinal direction of a pair of electrode wires, inrush current is uniformly restricted and the temperature rises. Effects such as preventing the speed from becoming non-uniform and eliminating local heat generation of the electrode wire are produced.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway side view of an embodiment of the flexible heating wire of the present invention, Fig. 2 is a resistance-temperature characteristic diagram of a PTC heating wire in an embodiment of the invention, and Fig. 3 is a diagram of the resistance-temperature characteristic of the PTC heating wire in an embodiment of the invention. The equivalent circuit diagram of the PTC heating wire is shown. 1: Core yarn, 2: Metal conductor wire, 3: PTC heating layer,
4: Outer covering.

Claims (1)

[Scope of Claims] 1 A heating element having a large positive temperature coefficient of resistance is disposed between at least one pair of electrodes in which a metal conductor wire is attached to a flexible core thread, and the heating element is covered with an insulating jacket. 1. A flexible heating wire, characterized in that the metal conductor wire is a copper alloy wire, the surface is made of a high-resistance metal oxide material, and the flexible heating wire is configured to directly contact the heating element. 2. The method according to claim 1, wherein a high-resistance material is provided on the surface of the metal conductor electrode so as to control the layer thickness of the organometallic chelate bond to produce conduction such as tunnel conduction or hopping conduction. Flexible heating wire.