JP2009087892A - Electric wire fuse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constitution in which insulating performance is secured even at the time of cutoff and meltdown operation by improving the sealing performance of an arc-extinguishing material used for the short circuit current cutoff of an electric wire fuse, and furthermore, which can follow a change of a fuse element. <P>SOLUTION: In the electric wire fuse, a wall to partition a meltdown chamber 11a and a cutoff chamber 11b is installed at an insulating cylindrical container which is divided into two pieces, the arc-extinguishing material 21 for the cutoff of the short circuit current is sealed into the insulating container, and the meltdown chamber 11a and the cutoff chamber 11b are partitioned by a partitioning plate 16 fitted to the wall. The circumferential part fitted to the wall and a retaining part to retain the fuse element 12 in a tight-contact state are formed of silicon rubber at the partitioning plate 16, and the circumferential part and the retaining part are coupled by a stainless plate and a steel plate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

 The present invention relates to an electric wire fuse used for a lead-in distribution line. Specifically, the present invention relates to an improvement of a sealing lid used for a wire fuse to hold an arc extinguishing material used for interrupting a short-circuit current.

 Conventionally, an electric wire fuse is connected to the lead-in wire for the protection of consumers. The electric wire fuse has a fusing part for fusing overcurrent and a cut-off part for cutting off the short-circuit current, and the arc-quenching material made of inorganic particulates such as silica sand is sealed in the cut-off part in a sealed state. Wire fuse is used.

For example, according to the content described in Patent Document 1, the arc extinguishing material sealing method for these electric wire fuses has a fuse element penetratingly held in an insulating cylinder made of an insulating material having an open end and a bottomed cylindrical shape. In this state, after the arc-extinguishing material is filled in the insulating cylinder, the opening has a structure in which the arc-extinguishing material is sealed with a partition plate made of a conductive material. In addition, since the partition plate also functions as an electrode, it is kept in a state of being electrically connected to the fuse element.
Furthermore, the content described in Patent Document 2 also shows a configuration similar to the above.

JP 59-228336 A Japanese Utility Model Publication No. 61-30951

As described above, the partition plate for sealing the arc extinguishing material is made of a metallic conductive material, and the fuse fuse element for the wire fuse and the partition plate are in close contact with each other. .
When the overcurrent is blown or the short-circuit current is cut off, the current is cut off due to the breakage of the fuse element, but the inside of the insulating cylinder is contaminated by the arc heat generated at the time of interruption, and the insulating performance inside the insulating cylinder is lowered. As a result, the electric circuit may be reclosed via the connection terminal via the inside of the insulating cylinder by the partition plate and the fuse element that are in contact with the insulating cylinder.

Further, since the partition plate has an electrode function and is formed of a metallic material such as a copper material, the adhesion to the fuse element and the insulating cylinder is poor, so that the arc extinguishing material made of inorganic particles is completely sealed and stored. The arc extinguishing material may spill into the fusing part. In this case, unless the arc-extinguishing material is hermetically housed in the required amount of interruption part, the interruption operation of the short-circuit current is not stable, which causes a public disaster.

Furthermore, in normal use, a current flows through the fuse element for electric wire fuses according to the amount of electricity used by consumers, and Joule heat is generated from the fuse elements. Due to the generated Joule heat, fuse elements and insulation cylinders with different coefficients of thermal expansion have a difference in expansion and contraction, and the partition plate does not have an elastic function to follow changes in the fuse element. Be bound. As a result, the expansion and contraction of the fuse element is concentrated on a part, resulting in abnormal breakage of the fuse element.

 In order to solve the problem of improving the hermeticity of the arc extinguishing material as described above, ensuring the insulation performance even during interruption and fusing operation, and further following the change of the fuse element, In the case 11d provided with the attaching part 11c provided in order to divide into the fusing chamber 11a which cuts off overcurrent, and the interruption | blocking chamber 11b which interrupt | blocks a short circuit current, the said interruption | blocking chamber 11b is for interrupting | blocking a short circuit current. An electric wire fuse 1 that fills the arc extinguishing material 21 made of an inorganic granular material, and holds the arc extinguishing material 21 in the cutoff chamber 11b by attaching the partition plate 16 to the mounting portion 11c, thereby separating the fusing chamber 11a and the cutoff chamber 11b. The partition plate 16 has a circumferential portion 16e fitted to the mounting portion 11c and a holding portion 16c for holding the fuse element 12 in close contact with a flame-retardant and insulating material silicon rubber. Form, moreover there is provided a wire fuse 1, characterized in that the holding portion 16c and the circumferential portion 16e are connected by the reinforcing member 16a of the metal plate stainless steel plate or the like.

 A stable short-circuit current because the arc extinguishing material hermetically sealed in the insulating cylinder does not leak by providing elastic silicon rubber at the location where the partition plate is in close contact with the fuse element and the insulating cylinder as described above. Can be shut off. In addition, since the fuse element is held by an elastic member, it can follow expansion and contraction operations due to heat, so that the deformation of the fuse element does not concentrate in one place, abnormal breakage does not occur, and a long-term reliable electric wire fuse can be obtained. Can be provided.

In addition, the use of a rigid material such as a stainless steel plate or steel plate for the partition plate ensures that the arc extinguishing material remains sealed even when an arc is released at the interrupting part when the short-circuit current is interrupted. Since the arc-extinguishing operation is stabilized, a safe interruption operation can be performed.

In addition, in the part where the fuse element and the insulating cylinder are in contact with each other on the partition plate, flame retardant and insulating silicon rubber is used, so that the fuse element is blown and the insulating cylinder is carbonized by arc heat. Even in such a case, since the insulating cylinder and the fuse element are insulative flame retardant and the insulating performance can be ensured by silicon rubber as an insulating material, it is possible to reliably maintain a state where the current is interrupted.

 The best mode for carrying out the present invention will be described based on the embodiment shown in FIGS.

FIG. 1 shows an electric wire fuse 1 that is used by being connected in the middle of a lead-in wire 15 of a low-voltage distribution line according to the present invention. The electric wire fuse 1 includes an electric wire fuse element 12 and connection terminals that are crimped to both ends thereof. 13 and the electric wire fuse element 12 are covered with the inner cylinder portion 11 and the outer cylinder 10 in a double manner and hermetically stored in a state isolated from the outside air, and the outer cylinder 10 is a part of the connection terminal 13 connected to the fuse element 1. It is molded so as to cover.

The outer cylinder 10 is formed by injection molding of the inner cylinder portion 11 and one end of the connection terminal 13 on both sides with a polycarbonate resin having high mechanical strength and high heat resistance, and a joint portion 10b of the outer cylinder 10 with the connection terminal 13 is integrally formed. Is provided with an airtight portion 10a for filling silicon rubber after injection molding. The hermetic portion 10a is for enhancing the adhesion between the connection terminal 13 and the outer cylinder 10 and keeping the inside of the wire fuse 1 in an airtight state.

FIG. 2 shows a cross section of the inner cylinder part 11 of the electric wire fuse 1. The inner cylinder part 11 is formed of a fuse element 12 made of a copper conductive wire formed substantially integrally and at both ends of the fuse element 12. Inner cylinder A, inner cylinder B and quartz sand, quartz sand, alumina hydroxide, etc., which are constituted by two parts for accommodating the crimped connection terminal 13 and the integrated fuse element 12 in a sealed state. The arc extinguishing material 21 is an inorganic granular material made of a mixture of granular materials or a single material thereof.

The fuse element 12 is made of a copper wire, and is formed integrally with a cut-off portion 12b and a fusing portion 12a made of a small diameter portion or a large diameter portion by a manufacturing method such as swaging or pressing. Further, a tin foil 12d is welded to the end portion of the small diameter portion that has been rotated about one rotation to the fusing portion 12a, and further, the blocking portion is provided with two large diameter portions, and the blocking portion 12b and the fusing portion 12a are provided. A support portion 12c having a large diameter portion is formed therebetween.

The connection terminal 13 is made of a copper material, and has a cylindrical shape. One end of the connection terminal 13 is a wire connection hole 13a for connecting the wire 15 and the other end is a connection hole for connecting to the end of the fuse element 12. 13b is provided. The end of the fuse element 12 is inserted into the connection hole 13b of the connection terminal 13, and the outer peripheral portion 13c of the connection terminal 13 is crimped and connected by caulking or the like, so that the fuse element 12 and the connection terminal 13 are integrated.

In addition, the wire connection hole 13a and the connection hole 13b provided in the connection terminal 13 are penetrated in order to prevent raindrops from entering the inside of the wire fuse 1 from the wire 15 crimped to the wire connection hole 13a by caulking or the like. I have not done it.

FIGS. 3 to 5 show the inner cylinder part 11 being assembled. The inner cylinder case 11d is composed of an inner cylinder (A) 19 and an inner cylinder (B) 20 that are divided into two in the axial direction. It is made of a resin material having high strength and heat resistance, for example, polycarbonate resin, and partition walls 19b and 20b are integrally formed in the central portion, and the fusing chambers 19h and 20h that cut off overcurrent and the short circuit current are cut off. It is divided into blocking rooms 19i and 20i.

Further, a partition plate 16 to be described later is fitted to the partition walls 19b and 20b, and an arc extinguishing material 21 for blocking a short-circuit current is sealed in the blocking chambers 19i and 20i. Note that the fusing chamber 11a and the blocking chamber 11b illustrated in FIG. 1 are configured by combining the inner cylinder (A) 19 and the inner cylinder (B) 20.

Further, both end portions of the inner cylinder (A) 19 and the inner cylinder (B) 20 are provided with terminal holding portions 19f and 20f for holding the connection terminals 13 integrated with the fuse element 12, and terminals of the fusing chambers 19h and 20h. Insulating walls 19c and 20c for holding the connection terminal 13 on the holding portion side, shielding arc heat generated at the time of fusing, and securing a portion that is not contaminated by the inner cylindrical case 11d are integrally formed.

The divided inner cylinder (A) 19 and inner cylinder (B) 20 are provided with a pair of protrusions 19d and 20d and fitting holes 19e and 20e in the vicinity of the terminal holding portion, and the divided surfaces are matched. By assembling, the protrusions 19d and 20d and the fitting holes 19e and 20e are combined to form a cylindrical inner cylinder case 11d.

The partition walls 19b and 20b provided at the substantially central portion of the inner cylinder (A) 19 and the inner cylinder (B) 20 will be described later in a substantially crescent shape with a notch at the center as shown in FIGS. Two walls are integrally formed so as to sandwich the partition plate 16. When the size of the cutout portions of the partition walls 19b and 20b is small, the insulation inside the insulating cylinder is lowered by the blocking operation, and the electric circuit may be reclosed by contact with the fused fuse element 12.

On the other hand, when the notch is large, the strength for holding the partition plate 16 to be described later is insufficient, and the increase of the internal pressure generated by the arc generated by the short-circuit current interrupting operation cannot be held by the partition plate 16 to extinguish the arc. In some cases, the material 21 flows out into the fusing chambers 19h and 20h and does not extinguish and cannot be shut off. A notch portion that satisfies both of these functions is formed.

FIG. 6 shows a partition plate 16 fitted to the partition walls 19b and 20b used in the electric wire fuse 1 of the present invention. The partition plate 16 is composed of two parts, and a hole 16f is provided in the center. It is composed of a reinforcing member 16a made of a metal plate such as a stainless steel plate and having a suitable strength and a cover 16b made of flame-retardant and insulating silicone rubber so as to cover the outer periphery thereof. .

The cover 16b has a holding portion 16c for holding the support portion 12c of the fuse element 12, and the holding portion 16c is formed with a holding hole 16d for holding the support portion 12c in close contact. Furthermore, the thickness of the circumferential portion 16e of the cover 16b is configured to be fitted to the partition walls 19b and 20b.

The partition walls 19b and 20b are not limited to the configuration in which the inner cylinder (A) 19 and the inner cylinder (B) 20 are erected from the inner walls, and may be grooves into which the circumferential portion 16e is fitted.

With this configuration, even if the internal pressure of the shut-off chambers 19i and 20i due to arc heat generated when the short-circuit current is interrupted increases, the reinforcing member 16a is configured to be strong, so that the partition plate 16 is not destroyed and is sealed. The arc extinguishing material 21 made of inorganic particulates held in the above is not spilled into the fusing chamber sides 19h, 20h. Therefore, the arc can be reliably extinguished and the interruption operation can be performed safely.

In addition, since the cover 16b is made of an elastic material and uses flame-retardant and insulating silicon rubber, and further protected by a heat-resistant sheet 18 made of an inorganic material, the partition plate 16 is burned out by a shut-off operation or a fusing operation. The insulation performance of the partition plate 16 can be ensured. Further, since the expansion and contraction of the fuse element 12 due to the influence of Joule heat generated by the current flowing through the fuse element 12 in a normal use state is not constrained, repeated stress is not applied to the fuse element 12 intensively. There is no local destruction of the fuse element 12.

In addition, the arc extinguishing material 21 made of fine inorganic particulates such as silica sand held in the shut-off chambers 19i and 20i in a sealed state is also attached to the fuse element 12 and the inner cylinder case 11d. Since it does not spill over to 20h, a reliable shut-off operation can be performed.

The partition plate 16 is not limited to the above-described configuration, and may be any configuration that can ensure the strength capable of withstanding the interruption operation, the expansion and contraction operation of the fuse element 12, and the insulation performance. For example, as shown in FIG. In this way, the reinforcing member 16a is exposed from the cover 16b toward the blocking chambers 19i and 20i, or as shown in FIG. 7B, the circumferential portion 16e of the reinforcing member 16a and the hole 16f provided at the center of the reinforcing member 16a. A cover made of silicon rubber may be formed.

In this case, the length of the circumferential portion 16e in the radial direction is to ensure insulation performance between the end portions (notch portions) of the partition walls 19b and 20b and the reinforcing member 16a in a state where the circumferential portion 16e is fitted to the inner cylinder case 11d. It is necessary to make it longer than the partition walls 19b and 20b. The cover 16b is not limited to silicon rubber, and may be any insulating and elastic material and flame retardant. For example, fluororubber or Teflon (registered trademark) rubber may be used.

Next, the assembly method in the electric wire fuse 1 of a present Example is demonstrated.
First, a tin alloy 12d is welded in the vicinity of the support portion 12c at the fusing portion 12a of the fuse element 12 for the wire fuse 1, and the partition plate 16 is inserted up to the support portion 12c, and then the heat-resistant sheet 18 is attached from the fusing portion 12a side of the fuse element 12. . Thereafter, the connection terminals 13 are inserted into both ends of the fuse element 12 to be crimped.

Next, the integrated fuse element 12 is assembled to the inner cylinder (A) 19. At this time, the partition plate 16 is fitted into partition walls 19b and 20b provided on the inner cylinder (A) 19, and the caulking portion 13c of the connection terminal 13 is further fitted to the caulking holding portion 19f of the inner cylinder (A) 19.

Thereafter, the inner cylinder (B) 20 is assembled to the split surface of the inner cylinder (A) 19. The inner cylinder (A) 19 is provided with a fitting pin 19d and a fitting hole 19e, and the inner cylinder (B) 20 is also provided with a fitting hole 20e and a fitting pin 20d. The inner cylinder case 11d is assembled by fitting 20d into the fitting holes 19e and 20e.
At this time, the partition plate 16 is assembled to the partition wall 20b of the inner cylinder (B) 20 so as to be fitted.

Next, as shown in FIG. 2, the arc-extinguishing material 21 is filled from the hole 17 provided in the inner cylinder (A) 19 and the lid 17 is press-fitted and assembled, whereby the assembly of the inner cylinder portion 11 is completed.

The assembled inner cylinder part 11 is set in the mold of the injection molding machine, and the outer cylinder 10 is injection molded.
After molding the outer cylinder, silicon rubber is injected into the airtight portion 10a formed by the connection terminal 13 and the outer cylinder 11, and the assembly of the electric wire fuse 1 is completed.

Next, the fusing operation and breaking operation of the electric wire fuse 1 will be described.
When an overcurrent flows to the fuse element 1, the copper wires at the fusing parts 19h and 20h are melted and the electric circuit is opened. At this time, the heat-resistant sheet 18 that covers the partition plate 16 has a function of preventing the partition plate 16 from being smoked by an arc caused by the fusing of the fuse element 12, thereby preventing an increase in the internal pressure of the wire fuse 1 and insulating. Performance can be secured.

When a short-circuit current flows through the fuse element 12, the copper wire of the interrupting portion 12b is melted and an arc is generated, but the arc extinguishing material 21 filled in the interrupting chambers 19i and 20i so as to surround the interrupting portion 12b. It is absorbed and cooled while penetrating the surface and the inside of the metal, and further, by forming an insulator with silicon or the like contained in the arc extinguishing material 21, the arc energy is absorbed and extinguished, thereby opening the electric circuit.

The figure showing the section of the electric wire fuse of this example The figure showing the inner cylinder part of a present Example Diagram showing the middle of the inner cylinder The perspective view from the inner cylinder cover B in the state which decomposed | disassembled the inner cylinder cover A of an inner cylinder part The perspective view from the inner cylinder cover A in the state which decomposed | disassembled the inner cylinder cover A of an inner cylinder part Partition plate used for the electric wire fuse of this embodiment Figure showing another embodiment of partition plate

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric wire fuse 10 Outer cylinder 11 Inner cylinder part 11a Fusing chamber 11b Shut off chamber 11c Mounting part 11d Inner cylinder case 12 Fuse element 16 Partition plate 16a Reinforcement member 16c Holding part 16e Circumferential part 19 Inner cylinder A
20 Inner cylinder B
21 Arc extinguishing material

Claims (1)

In the case 11d provided with the attaching part 11c provided in order to divide into the fusing chamber 11a which cuts off overcurrent, and the interruption | blocking chamber 11b which interrupt | blocks a short circuit current, the said interruption | blocking chamber 11b is for interrupting | blocking a short circuit current. An electric wire fuse 1 that fills the arc extinguishing material 21 made of an inorganic granular material, and holds the arc extinguishing material 21 in the cutoff chamber 11b by attaching the partition plate 16 to the mounting portion 11c, thereby separating the fusing chamber 11a and the cutoff chamber 11b. In
The partition plate 16 is formed with a peripheral portion 16e fitted to the mounting portion 11c and a holding portion 16c for holding the fuse element 12 in close contact with each other, made of a flame-retardant and insulating material silicon rubber. The electric wire fuse 1 characterized by connecting the circumference part 16e and the said holding part 16c with the reinforcement member 16a of metal plates, such as a stainless plate.

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