JP2022067385A - fuse - Google Patents

Abstract

To provide a fuse capable of increasing the insulation resistance after blocking even when a silicone resin is used as a filler material.CONSTITUTION: A space 4 in a case 12 of a fuse 1 is divided into a first space portion 4A containing one fusing portion (71A, 71A) and a second space portion 4B containing four fusing portions (73B, 73B to 73E, 73E). The first space portion 4A is filled with a first type of filler 3A containing only silica sand particles. The second space portion 4B is filled with a second type of filler 3B composed of a mixture of silicon sand particles and condensed thermosetting silicone resin particles, and obtained by melting and curing the condensed thermosetting silicone resin particles.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fuse in which a filler as an arc extinguishing agent is filled in a space inside the case so as to be in close contact with the conductor housed in the case and seal the conductor.

In FIGS. 1 to 3 of JP-A-2015-35338 (Patent Document 1), a current fuse or the like in which the space inside the case 12 is filled with the material 14 so as to seal the conductor 54 housed in the case 12. The protective element of is disclosed. In this protective element, the filler contains particulate alumina and a silicone resin, and in a specific embodiment, silicone rubber is used as the silicone resin. According to the publication, when the filler 14 is in close contact with the conductor 54 and the filler 14 seals the conductor 54, the heat generated by the conductor 54 due to energization can be easily generated by the conductor as compared with the case where there is a space around the filler 54. It is described that the conductor easily flows out of the 54 and the temperature rise of the conductor 54 due to the accumulation of heat for a long period of time can be suppressed. Further, it is described in the publication that it is not necessary to increase the cross-sectional area of the surface of the conductor 54 orthogonal to the direction in which the current flows in order to prepare for the conductor 54 to be blown by a small Joule heat integral value. There is. Further, when the filler 14 is in close contact with the conductor 54 and the filler 14 seals the conductor 54, the heat generated when the conductor 54 is fused causes the gas around the conductor 54 to expand, resulting in damage to the protective element. It is stated that it can be avoided and can improve the certainty, speed and safety of operation. Further, since the silicone resin has good heat resistance among the synthetic resins, the inclusion of the silicone resin in the filler 14 can suppress the deterioration of the filler 14 due to heat as compared with the case where other synthetic resins having poor heat resistance are contained. It is described as.

Japanese Unexamined Patent Publication No. 2015-35338

It is presumed that the silicone resin described in Cited Document 1 was dissolved in a liquid state with an organic solvent and then cured after filling the case. However, when the filler filled in the entire case is cured, the volume of the filler after curing varies. Therefore, special equipment and labor are required to fill the case with the cured filler. There is a problem that it takes. Further, the filler obtained by curing the silicone resin has a problem that the insulation resistance after blocking does not increase so much.

An object of the present invention is to provide a fuse in which the inside of a case can be easily filled with a filler even when a silicone resin is used as a filler material, and the insulation resistance after blocking can be increased. There is something in it.

The present invention includes a conductor having a plurality of fusing portions and a plurality of non-fusing portions, and at least one fusing portion is fused when a current having a Joule heat integral value equal to or higher than a predetermined value flows, and a case for accommodating the conductor. The subject is a fuse provided with an arc-extinguishing filler that fills the space within the case to seal the conductor. In the present invention, the space inside the case is one or more first space portions including at least one fusing portion included in the plurality of fusing portions of the conductor, and the rest other than the at least one fusing portion of the conductor. It is a second space portion of one or more including a fusing portion. The first space portion is filled with a first type of filler containing silica sand particles. The second space portion is filled with a second type of filler, which is composed of a mixture of silicon sand particles and silicone resin particles, and the silicone resin particles are melted and cured. It should be noted that one or more first space portions and one or more second space portions are formed as a result of filling the case with the first and second types of fillers.

One first space portion and one second space portion may be arranged in the longitudinal direction of the conductor portion, and second space portions are provided on both sides of the first space portion, respectively. The first space portions may be arranged in the longitudinal direction of the conductor portion, and the first space portions may be arranged in the longitudinal direction of the conductor portion on both sides of one second space portion, and are arranged alternately in the longitudinal direction of the conductor portion. The number of first and second spatial portions is arbitrary.

In the second space portion, a connecting portion made of a molten / cured silicone resin is formed between the particles of each silica sand, between the silica sand and the case, and between the silica sand and the fused portion of the conductor. As a result, the silicon sand and silicone resin melted by the heat of the arc when the conductor is fused form an insulator together with the melted conductor to extinguish the arc, and the presence of this insulator is conductive. It is possible to avoid damage to the protective element due to expansion of the gas around the body, and improve the certainty, speed and safety of operation. Moreover, in the present invention, since the first space portion is filled with the first kind of filler containing the silicon sand particles without containing the silicone resin particles, the silicone resin particles are melted and cured. Even if the volume of the second space portion created is not constant, the inside of the case can be easily filled with the filler. In particular, since the first space portion filled with the first type of filler containing silica sand particles without containing silicone resin particles exists as an almost completely insulating portion after blocking, the fuse after blocking The insulation resistance can be increased reliably.

The silicone is preferably a condensation-type thermosetting silicone resin. Condensation-type thermosetting silicone melts by heating to form a connecting portion without being liquefied using an organic solvent, which facilitates the manufacture of a fuse.

The composition of the conductor is arbitrary. A typical conductor is composed of a single wire conductor in which a plurality of narrow portions having a large resistance value and a plurality of large portions having a small resistance value are alternately arranged, and one narrow portion constitutes one fusing portion. One vast part constitutes one non-fusing part. As a conductor, a single wire conductor in which a plurality of narrow portions having a large resistance value and a plurality of large portions having a small resistance value are alternately arranged is connected in parallel to N (N is an integer of 2 or more) in parallel. N narrow portions adjacent to each other in the parallel direction of N single wire conductors form one fusing part, and N wide portions adjacent to each other in the parallel direction of N single wire conductors form one fusing part. Those constituting the two non-fusing portions may be used.

As the condensation type thermosetting silicone resin, those represented by the following chemical formulas can be used.

It is a perspective view of the appearance of the fuse of this embodiment. It is a vertical sectional view of the fuse of FIG. (A) to (C) are photographs taken by magnifying the mixture of natural silica sand, condensed thermosetting silicone resin particles, and natural silica sand particles and condensed thermosetting silicone resin particles 100 times with a microscope, respectively. be. (A) and (B) are the arc duration and recovery voltage of the fuse of the present embodiment for the confirmation test using the first kind of filler and the second kind of filler, and (C). And (D) are the arc duration characteristic and the recovery voltage characteristic of the fuse for the comparative test filled with only the second kind of filler consisting of the mixture of silica sand and the condensation type thermosetting silicone.

An example of an embodiment of the present invention will be described in detail with reference to the following drawings. FIG. 1 is a perspective view of the appearance of the fuse 1 of the present embodiment, and FIG. 2 is a vertical sectional view of the fuse 1.

The fuse 1 of the present embodiment has an insulating cylinder 5 in which a first type of filler 3A called arc-extinguishing sand and a second type of filler 3B are filled therein, and the cylinder 5 of the cylinder 5. It is provided with a pair of cap-shaped electrodes 9 and 11 fitted to both ends and electrically connected to a fuse element 7 as a conductor. L-shaped terminals 13 and 15 are fixed to the cap-shaped electrodes 9 and 11.

The tubular body 5 is integrally molded with ceramic. The fuse element 7 is a conductor integrally formed by pressing an elongated metal plate for a fuse made of silver or copper. The fuse element 7 of the present embodiment is a two single-wire conductor in which six wide portions 71A to 71E having a small resistance value and five narrow portions 73A to 73E having a large resistance value are alternately arranged side by side. 70A and 70B are composed of parallel conductors connected in parallel. Two narrow portions (for example, 73B and 73B) adjacent to each other in the parallel direction of the two single wire conductors 70A and 70B form one fusing portion, and are adjacent to each other in the parallel direction of the two single wire conductors 70A and 70B. Two vast parts (for example, 71B and 71B) constitute one non-fusing part. Therefore, in this fuse element 7, five blown portions and six non-blown portions are alternately arranged in the longitudinal direction of the fuse element 7.

In the present embodiment, the case 12 is composed of the tubular body 5 and the cap-shaped electrodes 9 and 11. The space 4 in the case 12 of the fuse 1 of the present embodiment includes a first space portion 4A including one fusing portion (71A, 71A) and four fusing portions (73B, 73B to 73E, 73E). It is divided into a second space portion 4B to be included. The first space portion 4A is filled with the first type of filler 3A containing only silica sand particles. Further, the second space portion 4B is composed of a mixture of silica sand particles and condensed thermosetting silicone resin particles, and the condensed thermosetting silicone resin particles are melted and cured to form a second type of filling. Material 3B is filled. In the second space portion 4B, between each silica sand, between the silica sand and the case 12, and between the silica sand and the blown portion of the fuse element 7 as a conductor, the fused and cured condensate thermosetting property. A connecting portion made of silicone resin is formed. Due to this structure, even if the volume of the second space portion 4B formed by melting and curing the particles of the condensed thermosetting silicone resin is not constant, the silica sand does not contain the particles of the condensed thermosetting silicone resin. The case 13 is filled with the filler by adjusting the volume of the first space portion 4A whose volume is determined by the filling amount of the first type filler 3A containing only particles.

Specifically, the second type of filler 3A is composed of a mixture of particles of natural silica sand and particles of a condensed thermosetting silicone resin. The heat of the arc generated after the blown part (73A, 73A to 73E, 73E) of the fuse element 7 melts melts the silica sand particles, and the arc is extinguished by the cooling effect of covering and fixing the surface of the fuse element 7. To. In the present embodiment, the first space portion filled with the first type of filler containing only the silica sand particles without containing the particles of the condensed thermosetting silicone resin is one fusing portion (7A, 7A) is included, and since this one fusing portion is surely fusing, the first space portion exists as an almost completely insulating portion (2000 MΩ or more) after the cutoff.

The condensation type thermosetting silicone contained in the second type of filler 3B used in the present embodiment is represented by the following chemical formula.

この縮合型熱硬化性シリコーン樹脂は、熱による反応によって、分子同士がつながっていき、熱硬化した状態においては、弾性や、圧縮性はほとんどない。したがってこのシリコーンは、硬化後に高い弾性と圧縮性を示すシリコーンゴムとは硬化後の性質が異なるものである。

In this condensed type thermosetting silicone resin, molecules are connected to each other by a reaction due to heat, and in a thermosetting state, there is almost no elasticity or compressibility. Therefore, this silicone has different properties after curing from silicone rubber, which exhibits high elasticity and compressibility after curing.

In this embodiment, the average particle size of the particles of natural silica sand is 245 μm, the average particle size of the particles of the condensed thermosetting silicone resin is 15 μm, and the ratio of the condensed thermosetting silicone in the mixture is 0 to 12. The mixture changed in the range of% was prepared as the second kind of filler 3A.

3A to 3C show natural silicon sand having an average particle diameter of 245 μm, condensed thermosetting silicone resin particles having an average particle diameter of 15 μm, and particles of these natural silica sand and condensed thermosetting silicone resin particles. It is a photograph taken by multiplying the mixture of the above (condensation type thermosetting silicone resin ratio is 7%) by 100 times with a microscope. As shown in FIG. 3 (C), in this mixture, it can be seen that a large number of small particles of the combined thermosetting silicone resin are clinging around the particles of the natural silicon sand.

As the first type of filler 3A, natural silica sand having an average particle diameter of 245 μm was prepared. In the specification of the present application, the average particle size means the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.

[Test fuse]
In order to confirm the breaking performance, a sterling silver plate is processed as the fuse element 7, and the width dimension of the narrow portion is, for example, 0.2 mm to 0.3 mm, and the width dimension of the wide portion is, for example, 6 mm to 7 mm. I prepared two in parallel.

Then, as a fuse for a comparative test, a fuse containing only the second type of filler in the case 12 was prepared. Further, for the confirmation test, a first type of filler was filled in the first space portion and the second type of filler was filled in the second space portion as in the above embodiment. ..

In each of the fuse for comparative test and the fuse for confirmation test, the heat-condensation type thermal effect silicone formed between each natural silica sand, between the natural silica sand and the case, and between the natural silica sand and the conductor. There was no large variation in the amount of connecting parts made of resin. In addition, both fuses were tested for breaking performance, and it was confirmed that the breaking performance was improved in both fuses.

However, when the insulation resistance after the cutoff was measured, the insulation resistance of the fuse for the comparative test was as large as several MΩ. It is considered that this is due to the presence of the carbon component of the condensed thermosetting silicone resin. On the other hand, all of the confirmation fuses had an insulation resistance of 2000 MΩ or more after being cut off. This is because in the part where the first type filler containing only silica sand without containing the condensed thermosetting silicone resin is present, the carbon component is not present in the layer of the first type filler after blocking. Therefore, it showed perfect insulation.

[Breaking characteristic test]
The breaking performance test of the fuse for the comparative test and the fuse for the confirmation test was performed according to the general rule of JIS8352. As a result, it was confirmed that the performance such as arc duration and recovery voltage was improved. FIG. 4 shows the results of testing the breaking characteristics of the fuse for the comparative test and the fuse for the confirmation test. 4 (A) and 4 (B) show the arc duration when the fuse of the present embodiment for the confirmation test using the first type filler 3A and the second type filler 3B is charged at 710 V. 4 (C) and 4 (D) show a comparative test fuse filled with only a second type of filler consisting of a mixture of silica sand and condensate thermosetting silicone, charged at 710 V. Arc duration characteristics and recovery voltage characteristics. As can be seen by comparing FIGS. 4 (B) and 4 (D), it can be seen that the arc duration of the fuse for the confirmation test of this embodiment is slightly longer than that of the fuse for the comparative test. Further, as can be seen by comparing FIGS. 4 (A) and 4 (C), it can be seen that the recovery voltage of the fuse manufactured in the present embodiment is stable as in the fuse of the comparative example. However, from the test results, the fuse for the confirmation test and the fuse for the comparative test do not differ significantly in the breaking characteristics. When the insulation resistance after the cutoff was measured as described above, the insulation resistance of each of the fuses for the comparative test was large and was about several MΩ, but in the fuse for the confirmation test of the present embodiment, all of them were found. The insulation resistance after interruption was 2000 MΩ or more. Therefore, in this respect, it was confirmed that the fuse of the present embodiment is practically superior.

[Mixing ratio test]
A test was conducted to confirm the mixing ratio of the condensed thermosetting silicone, which is a mixture of the particles of natural silica sand and the particles of the condensed thermosetting silicone resin. In this test, in the fuse for the comparative test, the mixing ratio of the condensation type thermosetting silicone was changed from 0% to 12%, and the arc current and the arc duration were measured. It was found that when the mixing ratio was 7% to 12%, the current squared time product arc I2t became small and the arc duration became short. Therefore, from this result, it can be seen that the mixing ratio is preferably 7% to 12%. Note that this preferred range is a confirmation test using the first type of filler 3A and the second type of filler 3B even if the rated capacity of the fuse changes and as in the embodiment shown in FIG. There is also substantially no change in the second type of filler 3B in the fuse of this embodiment for use.

[Number of cutoffs]
In the above embodiment, the first space portion 4A includes one non-blocking portion (71A, 71A) and one blocking portion (73A, 73A), but is included in the first space portion 4A. The number of cut-off portions to be generated should be smaller than the number of cut-off portions included in the second space portion 4B. This is because the second type of filler 3B is superior in blocking performance to the first type of filler 3A.

In the above embodiment, the first space portion 4A and the second space portion 4B are provided one by one, but a plurality of these space portions may exist. When there are a plurality of them, the first space portion 4A and the second space portion 4B may be arranged so as to be alternately arranged along the fuse element 7.

[others]
In the above embodiment, natural quartz sand is used, but it goes without saying that artificial quartz sand may be used.

Further, in the above embodiment, the above-mentioned chemical formula is used as the condensation type thermosetting silicone, but it can be naturally applied to the case where other condensation type thermosetting silicones are used.

Further, the shape of the fuse element is not limited to the shape of the present embodiment.

According to the present invention, even when silicone is used as the material of the filler for arc extinguishing, the insulation resistance after blocking can be increased.

1 Fuse 3A 1st type filler 3B 2nd type filler 4A 1st space part 4B 2nd space part 5 Cylinder 7 Fuse element 9, 11 Cap-shaped electrode 12 Case

Claims (8)

A conductor having a plurality of fusing portions and a plurality of non-fusing portions, and at least one of the fusing portions is fused when a current having a Joule heat integral value equal to or higher than a predetermined value flows.
A case for accommodating the conductor and
A fuse comprising an arc-extinguishing filler that fills the space inside the case so as to seal the conductor.
The space includes one or more first space portions including at least one fusing portion included in the plurality of fusing portions of the conductor, and the remaining fusing portions other than the at least one fusing portion of the conductor. Consists of one or more second spatial parts, including
The first space portion is filled with a first type of filler containing silica sand particles.
The second space portion is characterized in that it is composed of a mixture of silicon sand particles and silicone resin particles, and is filled with a second type of filler in which the silicone resin particles are melted and cured. Hughes to do. The fuse according to claim 1, wherein one said first space portion and one said second space portion are arranged in the longitudinal direction of the conductor. The fuse according to claim 1, wherein the second space portion is arranged on both sides of the first space portion in the longitudinal direction of the conductor. The fuse according to claim 1, wherein the first space portion is arranged on both sides of the second space portion in the longitudinal direction of the conductor. The fuse according to any one of claims 1 to 4, wherein the silicone resin is a condensation type thermosetting silicone resin. The conductor is composed of a single wire conductor in which a plurality of narrow portions having a large resistance value and a plurality of wide portions having a small resistance value are alternately arranged, and one narrow portion constitutes one fusing portion. The fuse according to any one of claims 1 to 4, wherein the one vast portion constitutes one non-fusing portion. The conductor is a parallel conductor in which N single-wire conductors (N is an integer of 2 or more) in which a plurality of narrow portions having a large resistance value and a plurality of large portions having a small resistance value are alternately arranged are connected in parallel. Composed of conductors
The N narrow portions adjacent to each other in the parallel direction of the N single wire conductors constitute one said fusing portion, and the N wide portions adjacent to each other in the parallel direction of the N single wire conductors form one. The fuse according to claim 1 to 4, which constitutes the two non-blown portions. The condensed thermosetting silicone resin is represented by the following chemical formula.

The fuse according to claim 4 or 7.

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