JP2014063639A - Electric wire with overcurrent cutoff function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric wire with an overcurrent cutoff function capable of breaking a circuit safely when an overcurrent is applied, at low cost.SOLUTION: In an electric wire 10 with an overcurrent cutoff function, a conductor 12 made of a metal having a melting point of 700°C or less is used. The conductor 12 is covered with an insulation coating 14. The conductor 12 is melted by an overcurrent.

Description

  The present invention relates to an electric wire with an overcurrent interruption function, and more particularly, to an electric wire with an overcurrent interruption function having a fuse function that breaks a conductor due to overcurrent and interrupts a circuit.

  In an electric circuit, in order to protect a device when an abnormal current flows, it is necessary to quickly cut off the circuit. In order to protect the circuit against overcurrent, a fuse is usually inserted in the electric circuit. Further, instead of inserting a fuse, a fusible link electric wire may be used as an electric wire having a function equivalent to that of a fuse.

Japanese Patent Laid-Open No. 02-213456

  When a fuse is installed in a circuit to protect the circuit against overcurrent, the cost of the fuse and the number of man-hours for installing the fuse are increased, which increases the cost. On the other hand, if the configuration does not use a fuse, the cost can be kept low. However, tin-plated annealed copper is used for conventional fusible link wires. Since soft copper has a high melting point, conventional fusible link electric wires generate a large amount of heat during fusing, and may damage surrounding equipment and insulation coating. Therefore, in Patent Document 1, a ceramic layer having high heat resistance is interposed between the conductor and the insulating coating. However, the formation of the ceramic layer is expensive, and the ceramic layer is hard and brittle, so that the handling property is not good.

  The problem to be solved by the present invention is to provide an electric wire with an overcurrent cutoff function that can cut off a circuit safely when an overcurrent is applied at low cost.

  In order to solve the above problems, an electric wire with an overcurrent interruption function according to the present invention is characterized in that a conductor made of a metal having a melting point of 700 ° C. or less is covered with an insulating coating, and the conductor is blown by overcurrent. is there.

  Further, another electric wire with an overcurrent cutoff function according to the present invention is characterized in that a conductor made of a metal having a melting point of 500 ° C. or less is covered with an insulating coating, and the conductor is blown by overcurrent. Further, another electric wire with an overcurrent interruption function according to the present invention is characterized in that a conductor made of a metal having a melting point of 350 ° C. or lower is covered with an insulating coating, and the conductor is blown by overcurrent.

  And in this invention, it is preferable that the space | gap is provided in the inner part rather than the insulation coating. And it is preferable that the ratio of the space | gap which occupies for an inner part rather than the said insulation coating is 5% or more.

  According to the electric wire with an overcurrent cutoff function according to the present invention, a low melting point metal having a melting point of 700 ° C. or less that is melted by overcurrent is used as a conductor, so that the amount of heat generated at the time of melting by overcurrent is small, and surrounding devices And the thermal effect on the insulation coating is small. Therefore, the circuit can be safely interrupted when an overcurrent is applied. In this case, since the fuse is not used in the circuit for circuit protection against overcurrent, the cost can be kept low.

  When the conductor is made of a metal having a melting point of 500 ° C. or lower, the amount of heat generated when fusing due to overcurrent is further reduced, so that the thermal influence on surrounding equipment and insulation coating is further reduced. Therefore, the circuit can be shut off more safely when an overcurrent is applied. When the conductor is made of a metal having a melting point of 350 ° C. or lower, the amount of heat generated at the time of fusing due to overcurrent is particularly small, so that the thermal influence on surrounding equipment and insulation coating is particularly small. Therefore, the circuit can be shut off particularly safely when an overcurrent is applied.

  At this time, if the ratio of the gap in the inner portion of the insulating coating is 5% or more, the conductor is likely to be deformed using the gap when the conductor is melted by overcurrent, so that the circuit is easily shut off. .

They are a schematic diagram (a) and an AA line sectional view (b) of an electric wire with an overcurrent interruption function concerning one embodiment of the present invention.

  Next, an embodiment of the present invention will be described in detail.

  In FIG. 1, the structure of the electric wire with an overcurrent interruption | blocking function which concerns on one Embodiment of this invention is shown. The electric wire 10 with an overcurrent interruption function has a conductor 12 composed of a plurality of metal wires 16, and the outer periphery of the conductor 12 is covered with an insulating coating 14.

  The plurality of metal strands 16 are bundled and twisted to form a stranded wire. The stranded wire is not compression-molded, and a gap 18a is formed between the metal wires 16 inside the stranded wire.

  The insulating coating 14 is formed in a cylindrical shape. The insulating coating 14 covers the outer periphery of the conductor 12 made of a stranded wire, and a gap 18 b is formed between the outer peripheral surface of the conductor 12 that is configured to be uneven and the inner peripheral surface of the insulating coating 14.

  The ratio of the gap in the inner portion of the insulating coating 14 is the insulation when the electric wire is cut in the radial direction (direction perpendicular to the axial direction) of the electric wire as shown in the cross-sectional view along the line AA in FIG. This can be represented by the area of the gap portions (18a, 18b) excluding the area of the conductor portion that occupies the inner portion of the coating 14.

  The plurality of metal strands 16 constituting the conductor 12 are formed of a low melting point metal. By using a metal having a low melting point for the conductor 12, the circuit can be cut off when an overcurrent is applied by fusing at a predetermined current value (overcurrent). That is, the metal used for the conductor 12 is blown by overcurrent. An overcurrent is a current that is larger than the current that normally flows through the circuit, and is an abnormal current. For example, a current that instantaneously flows in the circuit when the circuit is short-circuited.

  Examples of such a low melting point metal include Al, Sn, Pb, Zn, and alloys thereof.

  Examples of the metal that forms an alloy with Al, Sn, Pb, and Zn include Sb, Cu, Ag, Bi, Ge, Sn, Al, Mg, Fe, Mn, and Si. Examples of the Al alloy include an Al—Fe alloy, an Al—Si alloy, and an Al—Mg alloy. Examples of the Sn alloy include a Sn—Cu alloy, a Sn—Sb—Cu alloy, a Sn—Ag—Bi alloy, a Sn—Ag—Bi—Cu alloy, and a Sn—Ag—Bi—Cu—Ge alloy. Examples of the Pb alloy include a Pb—Sn—Cu alloy, a Pb—Ag—Sn alloy, and a Pb—Sn—Cu alloy. Examples of the Zn alloy include a Zn—Al alloy, a Zn—Al—Mg alloy, a Zn—Al—Cu—Mg alloy, a Zn—Al—Fe alloy, a Zn—Al—Cu alloy, a Zn—Cu alloy, and a Zn—Cu—Mg alloy. An alloy, a Zn-Mn alloy, a Zn-Fe alloy, etc. are mentioned.

The cross-sectional area of the conductor is preferably 0.5 mm ² or less from the viewpoint of easy melting at a predetermined current value (overcurrent). The diameter of the metal strand 16 is appropriately determined according to the number of the metal strands 16 so as to have a desired conductor cross-sectional area.

  The insulating material used for the insulating coating 14 is not particularly limited, and an insulating material used as a wire coating material can be applied. Examples of such an insulating material include vinyl chloride resin materials, olefin resin materials, engineering plastics, and the like.

  It is preferable that the insulation coating 14 is excellent in heat resistance so that the influence of heat when the conductor 12 is melted by overcurrent is reduced. Therefore, the insulating coating 14 may be cross-linked.

  According to the electric wire 10 with an overcurrent cutoff function having the above configuration, a low melting point metal having a melting point of 700 ° C. or less that is melted by overcurrent is used for the conductor 12, so that the amount of heat generated when melted by overcurrent is small. The thermal influence on surrounding devices and the insulation coating 14 is small. Therefore, the circuit can be safely interrupted when an overcurrent is applied. In this case, since the fuse is not used in the circuit for circuit protection against overcurrent, the cost can be kept low.

  And the space | gap 18a and the space | gap 18b are provided in the inside of the conductor 12 which consists of the several metal strand 16, and between the conductor 12 and the insulation coating 14, When the conductor 12 fuse | melts by overcurrent, the space | gap 18a or Since the conductor 12 can be deformed using the gap 18b, the conductor 12 is easily cut at the melted portion. That is, it is easy to interrupt the circuit.

  The melting point of the low melting point metal used for the conductor 12 is more preferably 500 ° C. or lower, and further preferably 350 ° C. or lower. When the melting point is 500 ° C. or lower, the amount of heat generated at the time of fusing due to overcurrent is much smaller, so the thermal influence on the surrounding equipment and the insulation coating 14 is even smaller. Therefore, the circuit can be shut off more safely when an overcurrent is applied. When the melting point is 350 ° C. or lower, the amount of heat generated at the time of fusing due to overcurrent is particularly small, so the thermal influence on surrounding equipment and insulation coating is particularly small. Therefore, the circuit can be shut off particularly safely when an overcurrent is applied.

  The electric wire with an overcurrent cutoff function according to the present invention may have a configuration in which no gap is provided inside the stranded wire or between the conductor and the insulating coating as long as the electric wire is melted by overcurrent. The conductor may be constituted by a single wire instead of a plurality of metal strands. Further, the insulating coating does not have to be formed into a cylindrical shape, and may be formed so as to be in close contact with the outer peripheral surface of the conductor. Further, when the conductor is composed of a plurality of metal strands, it may be compression molded.

  The electric wire with an overcurrent interruption function according to the present invention is an electric wire having a fuse function in which a conductor is blown by an overcurrent to interrupt a circuit. Therefore, the present invention can be applied to a part or all of various circuits into which fuses are inserted. In addition, since the resistance of the metal used for the conductor is relatively high, the electric wire with an overcurrent cutoff function according to the present invention is more suitable for a signal circuit such as a detection line that flows only a minute current than a power circuit that flows a large current. Preferably used.

  In the present invention, since an electric wire with an overcurrent interruption function is used for the entire length of the detection line or a part of the detection line, when the conductors of the detection line come into contact with each other and an overcurrent flows, the contact portion of the conductor instantaneously melts. By doing so, the detection circuit can be shut off. Thereby, equipment and other circuits can be protected.

  Hereinafter, the present invention will be described by way of examples.

(Example)
The alloys having the alloy compositions shown in Table 1 were each drawn to φ0.3 mm, and seven were twisted to form a stranded conductor. Thereafter, a vinyl chloride insulating material was extruded into a cylindrical shape on the outer periphery of the conductor as shown in FIG. 1B (covering thickness: 0.3 mm). This produced the electric wire with an overcurrent interruption function.

  The fusing characteristics of each manufactured electric wire with an overcurrent interruption function were examined. Moreover, the behavior at the time of a short circuit was investigated according to Evaluation 1. Furthermore, the behavior when a large current flows in the case of using each electric wire with an overcurrent cutoff function as a part of the wiring according to Evaluation 2 was examined. The measurement method and evaluation criteria are shown below. Moreover, these results are shown to Tables 1-2.

(Fusing characteristics)
A predetermined current was applied to the manufactured electric wire with an overcurrent interruption function (length: 1 m), and the time until the wire was broken (melting time) was measured.

(Evaluation 1)
Two electric wires with an overcurrent interruption function were prepared (each 50 cm in length), the conductor at one end of each electric wire was exposed 1 cm at a time, and the exposed conductors were lightly brought into contact with each other. While maintaining this state, electricity was applied at a predetermined current value from the other end, and the behavior at this time was examined. The case where the circuit was safely interrupted without causing smoke from the insulation coating or the combustion of the insulation coating due to the heat generated by the conductor was judged as “good”, and the case where the circuit was not safely intercepted was judged as “failed”.

(Evaluation 2)
An electric wire with an overcurrent cutoff function (length: 2 cm) produced by using a metal sleeve for a copper wire (conductor cross-sectional area: 0.5 mm ² , vinyl chloride insulating material, coating thickness: 0.3 mm, length: 1 m) The conductors were crimped and connected. This was energized at a predetermined current value, and the behavior at this time was examined. The case where the circuit was safely interrupted without causing smoke from the insulation coating or the combustion of the insulation coating due to the heat generated by the conductor was judged as “good”, and the case where the circuit was not safely intercepted was judged as “failed”.

  Each of the manufactured electric wires with an overcurrent cutoff function has a melting point of 700 ° C. or lower and a low melting point for any alloy constituting the conductor. In particular, some of the Sn alloy, Pb alloy, and Zn alloy have a melting point of 400 ° C. or lower and a lower melting point. In the evaluation of the fusing characteristics, disconnection was not caused by 0.5A energization and 1A energization, but these energization amounts were not overcurrent, and the amount of heat generated by the conductor was not large. It was. For energization of 10 A or more, any electric wire with an overcurrent cutoff function was disconnected. The energization of 10A required several seconds to 130 seconds, but since the conductor was blown out relatively quickly, no smoke was emitted from the insulation coating or combustion of the insulation coating was observed. Further, since the conductor was blown out quickly even at each energization amount of 50 A or more, no smoke was emitted from the insulation coating or combustion of the insulation coating was observed. And when melting | fusing point of a conductor metal was 500 degrees C or less, it was confirmed that the fusing time is remarkably short and the thermal influence which it has on insulation coating is remarkably small. Further, it was confirmed that when the melting point of the conductor metal is 350 ° C. or lower, the fusing time is further shortened and the thermal influence on the insulating coating is further reduced.

  In the evaluation 1, with respect to energization of 50 A or more, any electric wire with an overcurrent cutoff function was disconnected at the contact portion between the conductors. The circuit could be safely shut off without causing smoke from the insulation coating or burning of the insulation coating due to heat generated by the conductor.

  In the evaluation 2, in each case, with respect to energization of 50 A or more, the electric wire with an overcurrent interruption function was disconnected. The circuit could be safely shut off without causing smoke from the insulation coating or burning of the insulation coating due to heat generated by the conductor.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

10 Electric wire with overcurrent blocking function 12 Conductor 14 Insulation coating 16 Metal element wires 18a, 18b Air gap

Claims (5)

  An electric wire with an overcurrent interruption function, wherein a conductor made of a metal having a melting point of 700 ° C or less is covered with an insulating coating, and the conductor is melted by overcurrent.   An electric wire with an overcurrent cutoff function, wherein a conductor made of a metal having a melting point of 500 ° C or less is covered with an insulating coating, and the conductor is melted by an overcurrent. An electric wire with an overcurrent blocking function, wherein a conductor made of a metal having a melting point of 350 ° C or less is covered with an insulating coating, and the conductor is melted by an overcurrent.
  The electric wire with an overcurrent interruption function according to any one of claims 1 to 3, wherein a gap is provided inside the insulating coating.   The electric wire with an overcurrent interruption function according to claim 4, wherein a ratio of voids in an inner portion of the insulating coating is 5% or more.

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