JPS6319914Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an improvement of a fire detection line used to detect the occurrence of a fire.

A fire detection wire commonly used in the past has a two-core structure by covering a conductor 1 made of steel wire with a low-melting-point insulator 2 and twisting these two wires together, as shown in Figure 1, for example. It has a structure in which a presser tape 3 is wrapped around the outside and a synthetic resin sheath 4 is covered.

Depending on the purpose, this fire detection wire is wired on the ceiling etc. if indoors, or along the cable in the case of cable fire detection.In the event of a fire, the high heat will damage the insulator 2 on the conductor surface. When the conductor 1 is melted, the repulsive force of the untwisted conductor causes the conductors to short-circuit each other, forming a closed circuit and activating an alarm to notify the occurrence of a fire.

Recently, in the event of a major disaster such as a building fire, the importance of prompt detection of fire occurrence (occurrence and location of occurrence, etc.) and early extinguishing has been recognized. The demand for detection is becoming extremely high.

Further, in recent years, with the progress and spread of microcomputers, the reception technology for fire detection has significantly improved, and many detection technologies that can meet the above requirements have been proposed.

However, since the conventional fire detection wire mentioned above is a two-conductor wire, there is no problem in detecting the occurrence of a fire, but when detecting the location of a fire place, voltage must be applied between the two wire cores from the sending end of the fire detection wire. Then, it is necessary to calculate the short-circuit position between the conductors in the event of a fire by converting the length from the magnitude of the current flowing through the core conductor.In this case, there is an effect due to the contact resistance between the two cores of the fire detection wire.
This could hardly be said to be an appropriate configuration for general position detection.

In view of these circumstances, the inventors have made extensive studies and have found that it is important to provide at least one return wire made of conductive material to the conventional fire detection wire, in order to prevent the occurrence of a fire and the location of the fire. He discovered that it was extremely effective in detecting the position of people, and completed this idea.

That is, this invention is a fire detection wire made by twisting two wire cores coated with a synthetic resin insulator on a conductor made of steel wire or piano wire, wrapping a pressure tape thereon, and then applying a synthetic resin sheath. The fire detection wire is characterized in that a wire made of a conductive material is attached to the wire core when the wire cores are twisted together, or on top of the wire core after being wrapped with a holding tape.

Figures 2 to 4 show two embodiments of this invention.
3, and in these figures, 5 is a wire made of a conductive material, specifically copper or copper alloy, etc. If there is at least one wire, it is possible to detect a short circuit, but if two or more wires are placed, it is possible to detect a short circuit. By doing so, the short circuit detection accuracy can be further improved.

In the embodiment shown in FIG. 2, a bare wire 5 is attached to a wire core coated with a conductor 1, and in FIG. This is an example of attaching it vertically or by rolling it loosely.

The manner in which the fire detection wire of the present invention is used is shown in FIG. 4. A voltage is applied at both ends of one conductor 1a of the detection wire of the present invention using the wire (return wire) 2 made of a conductive material. A so-called Wheatstone bridge is formed between the receiver and the resistor to detect the position.

That is, in the figure, a power source _E0 on the receiver side is connected to one conductor 1a of the fire detection line of the present invention and a resistor R, and the balance position of the resistor is detected by a galvanometer A.

Now let each resistance value at the balance position of this resistor be R ₁ ,
R ₂ , the total length of the fire detection line of this invention to be installed is l, and the position from the receiver to the point of short circuit due to fire is x
Then, x is expressed by the following formula.

x=R ₁ /R ₁ +R ₂・l (m) In this way, by using the detection wire of the present invention, a Wheatstone bridge circuit can be easily constructed, and the configuration of the receiver side is therefore greatly simplified. The measurement of the short circuit point according to the above equation can be easily performed by providing an arithmetic circuit that calculates the ratio of the DC power supply voltage E ₀ of the receiver and the voltage E ₁ generated in the resistance portion R ₁ of the receiver resistance.

Since the wire made of a conductive material used in the fire detection wire of this invention is used as a lead wire as one side of the Wheatstone Bridge, it is desirable that its resistance be as low as possible.

Next, FIG. 5 shows another embodiment of this invention, in which the filament 5 is coated with a material having a higher melting point than the insulator 2 covering the conductor 1.
A has been applied.

Generally, when a fire occurs, higher heat than expected is generated, which may cause a short circuit between the conductor and the wire made of conductive material contained in the detection wire when the insulator melts. It can make it impossible.

In this embodiment, when a fire occurs, a short circuit between the conductors of the detection wire occurs earlier than a short circuit between the conductor of the detection wire and the wire made of a conductive material, and the short circuit point of the conductor is quickly detected on the receiver side. It was designed so that

As described above, this device has a structure in which a wire made of conductive material is attached to the two-core twisted wire of the coated conductor, so that by applying a voltage between the conductors, the current flowing through the conductor due to a short circuit in the event of a fire can be reduced. Compared to converting the short-circuit position into length based on the change, this method has the advantage of being much easier to detect the short-circuit position and simplifying the configuration of the receiving side, and has great industrial utility value.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional fire detection wire, Figures 2 and 3 are cross-sectional views of the fire detection wire of the present invention, Figure 4 is an explanatory diagram of an example of its use, and Figure 5 is a cross-sectional view of another fire detection wire of the present invention. FIG. 2 is a cross-sectional view of an embodiment. 1... Conductor, 2... Insulator, 3... Holding tape, 4... Sheath.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) Two wire cores covered with a synthetic resin insulator are twisted together on a conductor made of steel wire or piano wire, and a pressure tape is wrapped thereon and a synthetic resin sheath is applied. 1. A fire detection wire characterized in that a wire made of a conductive material is attached to the wire core when the wire cores are twisted together, or on top of the wire core after wrapping with a holding tape. (2) The fire detection wire according to the preceding paragraph (1), wherein the conductive material wire according to the above paragraph (1) is coated and insulated with a material having a higher melting point than the covering insulator of the wire core.