JP2000357444A - Alloy type thermal fuse and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy thermal fuse of axial type equipped with an enhanced resin seal strength while the quickness in the actuation of the fuse is well maintained. SOLUTION: Leads 2 are connected to the ends of a fusible alloy piece 1 having a low melting point, and flux 3 is applied to the alloy piece 1, and an insulating cylinder 4 whose inner surface at both the ends is tapered 42, is fitted on the alloy piece, and then a hardening type resin liquid is injected simultaneously to both the end parts of the cylinder 4, and the gaps between the ends and the leads are sealed. Thus an alloy type thermal fuse is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial type alloy type temperature fuse and a method for producing the same.

[0002]

2. Description of the Related Art Axial type alloy type temperature fuses include connecting a lead wire to both ends of a low melting point fusible alloy piece, applying a flux to the low melting point fusible alloy piece, and applying the flux. The insulation tube is inserted through the low melting point fusible alloy piece, and the space between each end of the insulation tube and each lead wire is sealed with a hardened resin. This alloy type temperature fuse is used by being attached to an electric device to be protected. When the electric device generates heat due to an overcurrent, the low melting point fusible alloy piece is blown by the generated heat, and the blown to the device. Is shut off, and abnormal heat generation of the device is prevented.

[0003] The fusing mechanism of the low melting point fusible alloy piece in this alloy type temperature fuse is based on the fact that the molten metal of the low melting point fusible alloy piece is subjected to the action of flux (antioxidation, cleaning action, wetting action). Then, the molten metal is spheroidized by the surface tension of the molten metal, and is divided by the progress of the spheroidization, an arc is generated during the division, and the arc disappears when the distance between the divisions reaches the arc breaking distance. The current interruption is terminated. In the operation of such a low-melting-point fusible alloy piece, the flux is vaporized by the generation of the arc, and a high internal pressure is generated.
If the resin sealing power is insufficient, the sealing portion is broken, and the molten alloy is scattered around, which is dangerous. Therefore, the above resin sealing force is important not only from the viewpoint of the pull-out resistance of the lead wire but also from the viewpoint of the internal pressure resistance during the operation of the temperature fuse.

[0004]

According to the results of the study by the present inventors, the sealing strength of the resin sealing portion of the above-mentioned axial type alloy type temperature fuse is such that both ends are simultaneously sealed and time-stamped. It turned out that there was a big difference with the stop. That is, when the resin liquid is simultaneously injected into both ends of the insulating cylinder, the pressure in the insulating cylinder is increased by the compression of air, and the difference between the pressure in the insulating cylinder and the injection pressure of the resin liquid disappears, and the depth of penetration of the resin liquid is reduced. It is difficult to provide sealing strength. On the other hand, if the both ends of the insulating cylinder are individually sealed with a time lag, the air is expelled from the other end while the resin liquid enters one end of the insulating cylinder, so that the pressure inside the insulating cylinder can be eliminated and the resin liquid can be deepened. They can invade.

[0005] However, in the latter case, the flux-applied low melting point fusible alloy piece is partially covered with the hardened resin because the resin liquid penetrates too deeply, and the melting and breaking of the low melting point fusible alloy piece is caused by the hardened resin coating. And the fusing operation of the temperature fuse may be reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the resin sealing strength of an axial type alloy type temperature fuse.
Another object of the present invention is to improve the quick operability of the nozzle while maintaining it.

[0007]

SUMMARY OF THE INVENTION A method of manufacturing an alloy-type temperature fuse according to the present invention comprises the steps of:
Wire, apply flux to the low-melting-point fusible alloy piece, insert an insulating cylinder with tapered inner surfaces on both ends on the flux-coated low-melting-point fusible alloy piece, and then insulate A curable resin liquid is simultaneously injected into both ends of the tube to seal between each end of the insulating tube and each lead wire.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1A,
1 is a low melting point fusible alloy piece, 2 and 2 are lead wires welded to both ends of the low melting point fusible alloy piece 3, and 3 is a flux applied to the low melting point fusible alloy piece after the welding of the lead wire. It is. This low melting point fusible alloy piece 1 includes tin, lead, bismuth, indium,
A material containing at least one of cadmium and the melting point of which is set to a desired temperature in accordance with the operating temperature of the temperature fuse is used, and the flux 3 mainly containing rosin can be used. The lead wire 1 may be a solder-plated copper wire, a tin-plated copper wire, a copper-coated steel wire, or the like, and may have some irregularities such as a brim in the middle of the lead. Numeral 4 denotes an insulating cylinder inserted on the flux-coated low-melting-point fusible alloy piece, with both end faces perpendicular to the outer peripheral side as shown in (b) of FIG. 1 (enlarged view in the dotted frame in (a) of FIG. 1). The face part 41 and the inner peripheral face
It is formed on the panel surface 42. The insulating cylinder 4 can be made of ceramics or plastics (for example, injection molded articles such as phenol resin, polycarbonate, polyphenylene sulfide, polyethylene terephthalate), and has a circular cross section. Also, those having an elliptical cross section can be used.

In FIG. 1A, reference numeral 5 denotes a tank for a curable resin liquid, for example, an epoxy resin liquid containing a filler (adding a powder of silica, calcium carbonate, aluminum or the like) or a urethane resin liquid. Nozzles 51 for discharging the resin liquid are provided at both ends of the cylinder. 52 is a pressurized air cylinder, 53 is a valve, and 54 is a control unit that opens and closes the valve 53 each time both ends of the insulating cylinder 4 are located in the nozzles 51, 51 to pressurize a fixed volume of pressurized air into the tank 5. It is.

As described above, both ends of the insulating cylinder 4 are connected to the nozzle 5
At positions 1, 51, the valve 53 is opened and closed, a fixed volume of pressurized air is pressed into the tank 5, and the resin liquid in the tank is discharged to each end of the insulating cylinder 4 by the press-in gas. You. A part of the discharged resin liquid is injected into the end of the insulating cylinder at the discharge pressure. However, since the injection is performed simultaneously at both ends of the insulating cylinder, the pressure in the insulating cylinder 4 is increased. Liquid intrusion is prevented.

However, in the present invention, the inner surfaces of both ends of the insulating cylinder 4 are formed on the taper surface 42, and since the taper surface 42 promotes the penetration of the resin liquid, the taper surface 4 is formed.
By setting the angle 2 to an appropriate angle, the penetration depth of the resin liquid can be set to a desired depth, and the curable resin liquid does not adhere to the flux-coated low-melting-point fusible alloy piece and each end of the insulating cylinder 4 And the lead wires 2 can be sealed with resin at a sufficient resin depth.

In the above description, the taper angle θ of the tapered surface 42 on the inner surface of the end of the insulating cylinder and the ratio γ of (the thickness a of the vertical end surface portion) / (the thickness of the insulating cylinder b) are θ = 5 ° to 50 °. ° preferably 10
° to 40 °, γ = 0.1 to 0.9, preferably 0.3 to
0.7. If the angle θ is less than 5 °, the taper surface portion 42 becomes long, and it is inevitable that the entire length of the insulating cylinder becomes longer.
When the ratio exceeds the above, the above-mentioned resin liquid penetration promoting effect can hardly be expected. If γ is less than 0.1, corner loss at the edge of the insulating cylinder is inevitable, and if γ exceeds 0.9, it becomes difficult to form an effective taper surface portion.

The outer peripheral portion, which is the non-tapered surface in the end surface of the insulating cylinder, is left as a vertical end surface 41 as shown in FIG. 1B, and a corner as shown in FIG. Chamfer (41
1) Yes.

In the alloy-type temperature fuse manufactured according to the present invention, both ends of the insulating cylinder can be sealed with a desired sufficiently deep sealing depth without adhesion of the cured resin to the flux-coated low melting point fusible alloy piece. As a result, the flux-coated low melting point fusible alloy piece can be smoothly melted and divided to ensure quick operability, and the flux is vaporized by the arc heat generated when the low melting point fusible alloy piece is melted and divided. Therefore, even if a high internal pressure is generated in the insulating cylinder, the destruction of the resin sealing portion can be prevented, the scattering of the molten alloy can be eliminated, and safe operation can be guaranteed.

In the above embodiment, harmony between prevention of adhesion of the sealing resin to the flux-coated low-melting-point fusible alloy piece and promotion of penetration of the sealing resin is performed only by adjusting the angle of the taper surface portion 42. As shown in FIG. 3, the inner peripheral side of the end surface of the insulating cylinder is defined as a vertical surface 412, and the tapered surface portion 42 intermediate the vertical surface 412.
It is also possible to carry out in cooperation with. In this case, the ratio η of (the thickness c of the inner peripheral side vertical surface portion) / (the thickness of the insulating cylinder b) is η
= 0.01-0.30, preferably 0.1-0.2. If it is less than 0.01, the effect of preventing adhesion of the sealing resin to the flux-coated low-melting-point fusible alloy piece can hardly be expected.
If it exceeds 30, the effect of preventing the sealing resin from adhering to the flux-applied low melting point fusible alloy piece exceeds the effect of promoting the penetration of the sealing resin and loses the significance of forming the tapered surface portion. Further, the taper angle θ of the taper surface 42 and the ratio γ of (the thickness a of the vertical end face portion) / (the thickness of the insulating cylinder b) are θ = 5 in the same manner as described above.
° to 50 °, preferably 10 ° to 40 °, γ = 0.1 to
0.9, preferably 0.3 to 0.7.

[0016]

EXAMPLE An axial type alloy-type temperature fuse was manufactured by the method described with reference to FIG. A ceramic cylinder with an outer diameter of 2.7 mm, a thickness of 0.5 mm, and a length of 9.3 mm was used as the insulating cylinder, and the taper angle θ was 30.0 °.
The ratio γ of (the thickness a of the vertical end face portion a) / (the thickness of the insulating cylinder b) was 0.40.

[Comparative Example] The same as the embodiment except that both end surfaces of the insulating cylinder were kept vertical.

Table 1 shows the lead wire withdrawal strength of each of the product of the example and the product of the comparative example (the number of each sample was 5).

Table 1 Average value (kgf) Range (kgf) Maximum value (kgf) Minimum value (kgf) Example product 8.12 0.2 8.2 8.0 Comparative product 6.03 1.5 6 .7 5.2

Further, when each sample was immersed in a heating oil 2 ° C. higher than the melting point of the low melting point fusible alloy piece and the fusing speed was measured, the difference between the example product and the comparative example product was as follows. Virtually not observed.

As is clear from these measurement results,
ADVANTAGE OF THE INVENTION According to this invention, operability can be maintained as it is and the sealing force of a resin sealing part can be enhanced well.

[0021]

According to the method of manufacturing the alloy type temperature fuse according to the present invention, the temperature fuse can be quickly operated only by forming both end surfaces of the insulating cylinder on the taper surface except for the outer peripheral portion. Can be maintained as it is, and the resin sealing strength can be improved. Therefore, even if the flux evaporates due to the arc heat generated during the fusing operation of the low melting point fusible alloy piece and a high internal pressure is generated, the scattering of the molten alloy can be prevented. Operation can be guaranteed.

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[Procedure amendment]

[Submission Date] June 25, 1999 (1999.6.2
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

SUMMARY OF THE INVENTION A method of manufacturing an alloy-type temperature fuse according to the present invention comprises the steps of:
Wire, apply flux to the low-melting-point fusible alloy piece, insert an insulating cylinder with tapered inner surfaces on both ends on the flux-coated low-melting-point fusible alloy piece, and then insulate The present invention is characterized in that a curable resin liquid is simultaneously (including substantially simultaneously) injected into both ends of the tube to seal between each end of the insulating tube and each lead wire. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 30, 1999 (1999.6.3)
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Added

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a view showing an example of a method for manufacturing an alloy-type temperature fuse according to the present invention.

FIG. 2 is a view showing a main part of an example of an insulating cylinder used in the alloy type temperature fuse according to the present invention.

FIG. 3 is a view showing a main part of another example of the insulating cylinder used in the alloy type temperature fuse according to the present invention.

[Explanation of Signs] 1 Low melting point fusible alloy 2 Lead wire 3 Flux 4 Insulating cylinder 41 Vertical surface 42 Tapered surface

Claims (3)

[Claims] A low-melting-point fusible alloy piece is connected to a lead wire at both ends, a flux is applied to the low-melting-point fusible alloy piece, and an insulating cylinder provided with tapered surfaces on the inner surfaces of both ends is formed by a flux. It is characterized in that it is inserted over the coated low melting point fusible alloy piece, and then the curable resin liquid is simultaneously injected into both ends of the insulating cylinder to seal the gap between each end of the insulating cylinder and each lead wire. Alloy mold temperature hue
Manufacturing method. 2. A lead wire is connected to both ends of a low melting point fusible alloy piece, and a flux is applied to the low melting point fusible alloy piece;
In the temperature fuse in which the insulating cylinder is inserted through the flux-coated low melting point fusible alloy piece and the space between each end of the insulating cylinder and each lead wire is sealed with a hardened resin, the end faces of both ends of the insulating cylinder are closed. An alloy-type temperature fuse having a tapered surface except for an outer peripheral portion. 3. The alloy type temperature fuse according to claim 2, wherein the inner peripheral side of the end face is formed in a vertical plane.