JPS6118606Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a wire fuse that is mainly used by intervening in the middle of electric wires, and is mainly used by interposing it in the middle of a low voltage drop-in line from the secondary side of a transformer. This relates to an electric wire fuse that is capable of preventing the electric wire sheathing from emitting smoke by immediately cutting off the current when the temperature of the electric wire connected to the electric wire rises and the sheathing emit smoke.

Conventional electric wire fuses have a structure in which a fusible substance is deposited approximately in the center of a long and thin main fusible body and housed in an insulating tube, but the fusible substance melts and evaporates when a large current is interrupted. There is a problem in that a large amount of metal vapor is generated, which causes arcing and deteriorates the breaking performance of the fuse. There is also the problem that the molten fusible material may adhere to the insulating tube and create holes in it. In order to solve this problem, conventionally, arc extinguishing agent was filled between the insulating cylinder and the fusible body to absorb the metal vapor and mechanically support the fusible body to eliminate the above problem. There is. However, such a device increases the material cost and, of course, increases the weight, and when used by interposing it in the middle of an electric wire, there is a problem that it places a burden on the electric wire.

Therefore, the present invention has been developed to eliminate the above-mentioned problems, and can prevent thermal deterioration of the fuse element due to inrush current at the start of motors, transformers, etc., while reducing the amount of metal vapor generated when large currents are interrupted. Even if the fuse element is left suspended in the insulating tube to reduce weight, it will still provide good breaking performance, and will also prevent damage to the insulating tube when interrupting large currents. It is an object of the present invention to provide an electric wire fuse that also enables the reuse of the insulating tube.

The drawings showing the embodiments of the present application will be described below. In the electric wire fuse A, 1 is an insulating cylinder, which is formed using a transparent hard insulating material such as a weather-resistant transparent hard synthetic resin or reinforced glass, and allows the state of the fuse element 2 provided inside to be visually confirmed. It's becoming like that. The fuse element 2 is constructed by fixing a heat storage body 4 to a silver wire 3. Furthermore, since the silver wire 3 can generate less metal vapor when the fuse is cut off than an element made of a conventional low melting point alloy, it is possible to suppress an increase in the internal pressure of the insulating cylinder 1 when the fuse is cut off. . Also, no decrease in megger (insulation resistance) was observed after the circuit was shut off. That is, since the amount of metal vapor is small, adhesion of metal vapor to the inner wall of the insulating cylinder 1 can also be reduced. Furthermore, a copper tube is used as the heat storage body 4, which is passed through the silver wire 3 and then caulked and crimped. In the heat storage body 4, the silver wire is an electric motor,
It is designed to prevent thermal deterioration, such as melting, due to the inrush current at the start of transformers, capacitors, etc., that is, transient current, and is designed to absorb the heat generated by the above current. . Furthermore, by changing the heat capacity (size) of the heat storage body 4, the current-time characteristics (fusing characteristics) of the fuse, that is, the fusing time can be made faster or slower, and the predetermined fuse blowing characteristics can be easily adjusted. is obtained.
The positional relationship of the heat storage body 4 with respect to the silver wire 3 is as follows:
The effective distance l ₁ =l ₂ shown in the figure is not reached. This is heat storage element 4 that became red hot when the fuse fused.
This prevents the metal from falling onto the inner wall of the insulating cylinder 1 and causing burnout. For example, by setting the above distance to l ₁ > l ₂ as shown in the figure, the resistance value r ₁ between l ₁ and
The resistance value r ₂ between l ₂ and r ₁ > r ₂ are set so that the melting occurs between l ₁ . Reference numeral 5 denotes a round bar-shaped terminal fitting for connecting electric wires, which is made of copper or other conductive material, and has a fuse element connection part 5b formed at one end of the base part 5a located inside the insulating cylinder 1.
One end of the fuse element 2 is inserted and secured by brazing. Further, a hollow electric wire connecting portion 5c is provided on the other side of the insulating cylinder 1 that protrudes to the outside, and an electric wire is inserted into this through the opening portion 5d for crimping connection. Reference numeral 6 denotes a wire insertion guide attached to the end of the connecting portion 5c, which is made of an insulator. This prevents the insertion of the electric wire from being obstructed by arc chips generated between the electric wire to be connected and the terminal fitting 5 when working with live wires. Reference numeral 7 denotes an insulating terminal cover, which covers the connecting portion 5c of the terminal fitting 5. Next, reference numeral 9 denotes a support located at the end of the insulating cylinder 1, which is made of a hard synthetic resin having heat insulating properties or other hard insulating material, and is inserted into a through hole 10 formed through approximately the center of the support. The base portion 5a of the terminal fitting 5 is positioned and held in a predetermined position. As clearly shown in FIG. 2, reference numeral 11 denotes a plurality of gas exhaust holes formed in the support body 9 in a direction substantially parallel to the axial direction of the terminal fitting 5, so as to communicate the inside and outside of the insulating cylinder 1. ing. As shown in FIG. 3, reference numeral 12 indicates an engaging protrusion formed protrudingly on a part of the outer periphery of the support body 9, which engages in a fitting manner with a concave engaging portion 13 provided at the end of the insulating cylinder 1. Together,
The support body 9 and the insulating cylinder 1 are designed to be integrated. Further, the contact portion 14 between the outer periphery of the support body 9 and the inner peripheral wall of the insulating cylinder 1 may be fixed with an epoxy adhesive as required. Reference numeral 15 denotes a reinforcing pin made of a metal material, which is driven into the through holes 1', 9', and 5' formed in a continuous manner in the insulating tube 1, the support body 9, and the terminal fitting 5, respectively, and penetrates through the holes 1', 9', and 5'. They are fixed together to prevent them from rotating.
Further, the pin 15 is fixed with an epoxy adhesive to prevent it from falling off and to ensure stronger integrity. Reference numeral 16 denotes an insulating cover that closes the opening of the insulating cylinder 1 to prevent rainwater from entering the cylinder, and is made of a material that has excellent weather resistance, tracking resistance, flame resistance, and flexibility. insulation material e.g.
EPT (ethylene propylene rubber) is used. At the joint between the insulating cover 16 and the insulating cylinder 1, an annular projection 17 is integrally formed on the inner periphery of the tip of the insulating cover 16, and this projection 17 is fitted into a fitting recess 18 formed correspondingly to the insulating cylinder 1. , the adhesion between the cover 16 and the tube 1 is increased,
Furthermore, these are bonded together using a silicon adhesive that also serves as a sealing material. Further, at the joint portion between the insulating cover 16 and the terminal fitting 5, an annular projection 19 is integrally formed on the inner periphery of the cover 16, and a fitting recess 20 is formed in which the projection 19 corresponds to the terminal fitting 5. They are fitted and brought into close contact, and are further joined with an adhesive.
21 is the cover 16 on the outer periphery of the insulating cylinder 1.
When the insulating cover 16 is attached to the insulating tube 1, the adhesive attached to the outer periphery of the insulating tube 1 prevents the insulating cover 16 from fitting into the insulating cover 16. This prevents the adhesive from being pushed out and flowing out, and even if the adhesive does flow out, it can be easily wiped off. Furthermore, the stop part 2
1 also has a water draining effect that blocks rainwater etc. from flowing on the outer surface of the insulating cylinder 1.

In the electric wire fuse A described above, the structures at both ends of the insulating cylinder 1 are symmetrical.

To briefly explain the assembly of the above-mentioned structure, first, the fuse element 2 and the terminal fitting 5 are connected in advance and inserted into the insulating tube 1, and the support 9 is connected to the terminal fitting 5 and the insulating tube. 1 as described above. In this case, the support body 9 may be inserted into the insulating tube 1 after being attached to the terminal fitting 5. After attachment, reinforcing pins 15 are driven in to firmly and integrally fix insulating cylinder 1, support body 9, and terminal fitting 5 to each other. Next, by fitting and attaching the insulating cover 16 to the open end of the insulating tube 1 as described above, the interior of the insulating tube 1 will be completely waterproof.

Next, the electric wire fuse assembled as described above is used by being connected to the middle of a low-voltage drop-in line, as is generally known. In this usage state, when the temperature of the low-voltage wire increases and smoke is generated, the fuse element 2 blows as described above, cutting off the current and cutting off the wires connected to the fuse. , smoke generation from electric wires is prevented. Further, at this time of interruption, the arc, that is, abnormal pressure and its gas generated within the insulating cylinder 1 are discharged through the insulating cover 1 through a plurality of exhaust holes 11 provided in the support 9.
6, whereby the insulating cover 16 bulges due to its own flexibility. As a result, the insulation cover 16
The close contact portion between the insulating tube 1 and the insulating cover 16 and the close contact portion of the terminal fitting 5 separates, and the abnormal pressure and its gas can be quickly discharged to the outside from here, and the insulating tube 1 is destroyed. Never.

In the present invention, the fuse element 2 is constructed by fixing a heat storage body 4 having a larger heat capacity than the silver wire 3 to the middle part of the silver wire.
When a starting inrush current flows in an electric motor or a transformer, the heat generated in the silver wire 3 is absorbed by the heat storage body 4,
This has the effect of preventing thermal deterioration of the silver wire 3 and thus lengthening its life.

On the other hand, since the heat storage body 4 is made of a material with a higher melting point than the silver wire 3, when a large current is passed through the fuse and is interrupted, only the thin part of the silver wire 3 is fused. This has the effect of allowing the thick heat storage body 4 to remain, reducing the amount of metal vapor generated at the time of fusing, and improving the above-mentioned large current interrupting characteristics.

Moreover, since the heat storage body 4 is fixed at a location where l ₁ > l ₂ as described above, a large current flows through the silver wire 3.
When fused, the silver wire 3 has the advantage of being able to cause the fusion to occur on the l ₁ side and leave the l ₂ side unfused. (1) The area around the heat storage body 4 is hollow, and there is nothing other than the silver wire 3 (no filler, etc.), and there is no support for the heat storage body 4 (lighter weight). Even if the heat storage body 4 (heat storage body heated by heat generation of the silver wire 3) is prevented from falling onto the inner surface of the insulating tube 1, It can prevent holes caused by burnout in step 1.
This has the effect of maintaining the waterproofness of the insulating tube 1 and enabling its reuse, and (2) the short side of the silver wire 3, that is, the terminal fitting and the heat storage body 4.
By leaving the side with the smaller distance unfused, the heat storage element 4 can be held in a cantilever state (extruded state) even with a thin silver wire, and the heat storage element 4 can be held in a cantilevered state (extruded state) even with a thin silver wire. As a result of crimping, the heat storage body does not move relative to the silver wire, and as a result,
It is possible to stably support the high-temperature heat storage body 4, and there is also an effect that the reliability of the effect (1) above can be increased.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, in which Fig. 1 is a partially cutaway view of an electric wire fuse, Fig. 2 is a sectional view taken along the - line in Fig. 1, and Fig. 3 is a - line sectional view in Fig. 2.
Line partial sectional view. 1...Insulating tube, 2...Fuse element, 5
... terminal fitting, 9 ... support body, 11 ... gas discharge hole, 12 ... engagement projection, 13 ... recessed engagement part, 15 ... reinforcement pin, 16 ... insulation cover.

Claims (1)

[Scope of utility model registration request] In an electric wire fuse, a fuse element is provided in a hollow insulating cylinder that is equipped with terminal fittings for connecting electric wires at one end and the other end, respectively, and the fuse element is placed between the two terminal fittings. In addition to stretching the silver wire, a copper tube is placed in the middle of the silver wire to absorb the heat generated in the silver wire, which is a heat storage body with a larger heat capacity than the silver wire and also has a higher melting point than the silver wire. The heat storage body is fixed by crimping means, and the fixing position of the heat storage body is such that the length of the silver wire between the heat storage body and one terminal fitting is the same as the length of the silver wire between the heat storage body and the other terminal fitting. An electric wire fuse characterized by being set at a position where the length is shorter than the length of the silver wire between the wires.