JPH0536344A - Fuse - Google Patents

Abstract

PURPOSE:To sharply improve the short-circuit cutoff performance by dissipating the heat energy generated at the time of a short-circuit cutoff before an envelope is broken. CONSTITUTION:A metal wire 12 serving as a fuse element is stretched between a pair of metal terminals 11, 11. Outer ends of the metal terminals 11, 11 are guided to the outside, and the metal wire 12 and connection sections between the metal wire 12 and the terminals 11, 11 are stored in an envelope 13 made of an insulating material. The surrounding of the metal wire 12 is covered with foaming resin 15. Neither cracking nor splitting occurs on the envelope 13 when the pressure in the envelope 13 is increased by the melting and vaporization of the metal wire 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse serving as a protection element for protecting electronic parts, electronic equipment, etc. from overcurrent.

[0002]

2. Description of the Related Art In general, a fuse protecting function is performed by cutting an electric current path by melting and vaporizing a metal wire by its Joule heat when an overcurrent flows through the metal wire which is a fusible body.

Further, when the metal wire, which is a fusible body, is melted, the metal vaporizes, so that the pressure inside the envelope accommodating the metal wire rises.

From the point of view of merely overload current protection, the fuse protection function is completed by melting and vaporizing a small portion of the central portion of the metal wire, which is a fusible body, where heat dissipation is least likely to occur. However, a large current flowing due to a short circuit causes the metal wire, which is a fusible material, to be uniformly heated and melted,
Further, after melting, the metal wire is vaporized rapidly.

As described above, in the fusing by the short-circuit current, a large amount of heat energy is generated instantaneously, and the internal pressure also increases.

[0006] Such an increase in internal pressure causes a mechanical load on the envelope, and in the worst case, an abnormal situation such as damage to the envelope occurs.

In order to secure the short-circuit breaking performance of such a fuse, conventionally, as shown in FIG. 7, a space 3 is provided in the envelope 2 in consideration of the metal amount of the metal wire 1, and this metal wire is provided. 1
A structure is adopted in which the terminals 4 and 4 connected to both ends of the enclosure are led out of the envelope 2.

However, with the recent rapid downsizing of electronic components and the increasing demand for fuses, short-circuit breaking performance is ensured by simply forming a space 3 inside the envelope 2 and at the same time, It is difficult to meet the demand for downsizing with a structure that prevents the vessel 2 from being destroyed.

Then, for example, Jitsuko Sho 58-38988.
As described in Japanese Patent Publication No. JP-A-2003-264, there is known a fuse having a structure in which a fusible metal wire is covered with a flexible synthetic resin and the function of the space portion is replaced with a flexible resin.

[0010]

However, in the fuse having the structure in which the fusible metal wire is covered with the conventional synthetic resin having flexibility, the fuse having a mechanical load of the envelope can withstand a sufficient short circuit breaking performance. There is a problem that cannot be done.

Therefore, as shown in FIG. 8, the inventor further forms the second space 6 by covering the fusible metal wire 1 housed in the envelope 2 with a box-like enclosure frame 5. As a result, when the metal wire 1 is melted and vaporized, the pressure in the second space 6 rises, and even if the enclosure frame 5 cannot withstand the pressure and is damaged by cracks, cracks, etc., the heat energy is dissipated during that time. The energy required to damage the envelope 2 is consumed, and the load applied to the envelope 2 is reduced.

The present invention surely dissipates the heat energy generated at the time of short-circuit interruption before the damage to the envelope, and makes more effective use of the space of the envelope to greatly improve the short-circuit interruption performance. A fuse that can be designed is provided.

[0013]

As shown in FIG. 1, in a fuse of the present invention, a metal wire 12, which is a fusible body, is stretched between a pair of metal terminals 11 and 11, and the metal terminals 11 and 11 are In the fuse 14 in which the metal wire 12 and the connecting portion between the metal wire 12 and the terminals 11 and 11 are housed in the envelope 13 made of an insulating material so that each outer end is led out to the outside, the metal wire 12 The area around is covered with a foamable resin 15.

[0014]

In the fuse of the present invention, since the metal wire 12 which is a fusible body is covered with the foaming resin 15, the metal wire 12 is surrounded by an infinite number of spaces formed by the foaming resin 15. That is, when the soluble metal wire 12 is melted and vaporized, the pressure in the infinitely divided space portion rises, and even if a part of the portion forming each divided space is damaged, in the meantime. Thermal energy is dissipated, the energy required to damage the envelope 13 is consumed, the load on the envelope 13 is reduced, the envelope 13 is not damaged, and sufficient short-circuit cutoff is performed. Performance can be secured.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described with reference to FIGS.

Reference numeral 20 denotes a metal wire which is a fusible material.
Is stretched between a pair of metal terminals 21, 21. And
The outer ends of the metal terminals 21 and 21 are led out to the outside to form a metal wire.
20 is housed in the envelope 22 through the opening 23 of the envelope 22 formed of an insulating material, for example, polyether sulfone. From the opening 23 of the envelope 22, a foamable resin
24, for example, Shin-Etsu Chemical Co., Ltd. KE521 (A.
B) is poured, the metal wire 20 and the metal wire 20 and the terminal 2
The area around the connection with 1, 21 is covered with a foaming resin 24.

Further, a foaming resin 24 is filled and the opening 23 of the envelope 22 is covered with a lid 25 formed of an insulating resin, for example, polyethylene terephthalate.

Next, the operation of this embodiment will be described.

Since the metal wire 21 which is a fusible body is covered with the foaming resin 24, a space innumerable divided by the foaming resin 24 is formed around the metal wire 21. When the metal wire 21 of is melted and vaporized, the pressure in the innumerable divided space portion rises, and even if a part of the portion forming each divided space is damaged, thermal energy is dissipated during that time, Energy required to damage the envelope 22 is consumed. Therefore, the load on the envelope 22 is reduced and the envelope 22 is not damaged.

Next, the results of comparative experiments will be described in order to qualitatively express the effects of the present invention. Sample A has the structure shown in the above embodiment and is shown in FIG. Sample B is shown in FIG.
As shown in FIG. 3, the conventional structure has the space portion 33 formed around the fusible metal wire 32 in which the metal terminals 31 are connected to both ends of the envelope 30 and accommodated therein. Further, in the sample C, as shown in FIG. 6, a flexible resin 38 (silicone varnish KR manufactured by Shin-Etsu Chemical Co., Ltd.) is used around the soluble metal wire 37 which is housed in the envelope 35 with the metal terminals 36 connected to both ends. -2038).

A short circuit interruption test was conducted on each of the samples A to C under a standard condition of a direct current of 130 V, 50 amperes and a time constant of 1.3 milliseconds, and the results shown in Table 1 below were obtained. Was given.

[0022]

[Table 1]

In Table 1, the mark "O" indicates that the current was cut off without any problem, and the mark "X" indicates that the current could not be cut off, or that the envelope had abnormalities such as cracks or cracks.

As a result of this experiment, all the fuses of Sample A in which the metal wire was covered with the foamed resin cut off the current without any problem,
It was confirmed that the fuse of the present invention has excellent performance. In addition, sample B in which a space is formed around the metal wire
All fuses could not extinguish the arc between the terminals, and the envelope was destroyed. Furthermore, in the case of a fuse in which the metal wire was covered with a flexible resin, 3/5 of the fuses were found to have abnormalities such as cracks and cracks in the envelope. Further, in the above-described embodiment, the structure in which the soluble metal wire is covered with the foamed resin has been described, but it is also possible to combine the foamable resin with the flexible resin. Further, a filler such as an arc extinguishing material may be dispersed in the foamable resin to improve the short circuit breaking performance without damaging the envelope.

Further, in the above-mentioned embodiment, the foamable resin is flown into the box-shaped envelope, but the invention is not limited to this method. For example, the foamable resin is molded around the soluble metal wire by casting or the like. Alternatively, the envelope may be cast, and further manufactured by low-pressure transfer molding or the like.

[0026]

According to the present invention, since the fusible metal wire is covered with the foaming resin, even if the pressure inside the envelope rises due to the vaporization of the metal wire with a simple structure, the envelope does not Short-circuit breaking performance can be improved without cracking or cracking.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a fuse of the present invention.

FIG. 2A is an exploded front view of a fuse showing one embodiment of the present invention, and b is an exploded side view.

FIG. 3 is a vertical cross-sectional view showing a state in which the upper lid is removed.

FIG. 4 is a vertical sectional view of the same.

FIG. 5 is a vertical sectional view of a conventional fuse.

FIG. 6 is a vertical cross-sectional view of another conventional fuse.

FIG. 7 is an explanatory diagram of a conventional fuse.

FIG. 8 is an explanatory diagram of a fuse which is a premise of the present invention.

[Explanation of symbols]

 11 Metal terminal 12 Metal wire 13 Enclosure 15 Resin

Claims (1)

Claim: What is claimed is: 1. A metal wire, which is a fusible body, is stretched between a pair of metal terminals, and the metal wire and the metal wire are arranged so that each outer end of the metal terminal is led out to the outside. A fuse in which a connecting portion with the terminal is housed in an envelope made of an insulating material, wherein the metal wire is covered with a foaming resin.