JPH065176A - Temperature fuse - Google Patents

Abstract

PURPOSE:To enhance shock-resistivity and rated current capacity of a temperature fuse by using a metallic body coated with an insulating material as a cylindrical case for accomodating a fusible alloy with lead wires connected to its both ends. CONSTITUTION:Lead wires 2 and 2 are connected to both ends of a rod-like fusible alloy 1 to be fused in excess of a preset temperature. The fusible alloy 1 is accomodated in a cylindrical case 9 consisting of a metallic cylinder 7, internal and external surfaces of which are coated with an insulating material 8 (for example, a silicone high molecular insulating material). Both ends of the cylindrical case 9 are sealed with sealant resin 4 and 4, while the lead wires 2 and 2 are sealed and fixed, so as to manufacture a fusible alloy type temperature fuse 6. Accordingly, since the cylindrical case 9 is mainly composed of the metallic cylinder 7, its strength against shock is enhanced so that no breakage take place when being handled, such as for attaching to an apparatus. In addition, since no breakage takes place due to an internal spark caused when large current is shut off, its rated current capacity can be increased as the result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of impact resistance and current capacity of a fusible alloy type thermal fuse.

[0002]

2. Description of the Related Art A fusible alloy type thermal fuse known as a relatively inexpensive thermal fuse has a structure as shown in FIG.

In FIG. 2, 1 is a rod-shaped fusible alloy that melts when a predetermined temperature is exceeded, 2 and 2 are leads connected to both ends of the fusible alloy 1, and 3 is a ceramic containing the fusible alloy 1. The cylindrical cases 4 and 4 are sealing resins for sealing both ends of the cylindrical case 3 and at the same time sealing and fixing the leads 2 and 2. A flux (not shown) is applied around the fusible alloy 1 to smooth the surface state of the melted fusible alloy 1 and to smoothly separate the leads on both leads.

The fusible alloy type thermal fuse 5 is assembled in the device by utilizing its leads 2, 2 and blows off when the ambient temperature reaches the melting point of the fusible alloy 1 to cut off the electric current.

[0005]

In the fusible alloy type thermal fuse 5, since the material of the tubular case 3 is ceramics, it has a hard property but a brittle property, and is broken by an impact applied during assembling work or the like. And lacks reliability against mechanical shock. Further, when a large spark is generated at the time of fusing, it may be cracked due to the impact, which causes a problem to the parts assembled in the surroundings, so that there is a problem that the current capacity is limited.

Therefore, the present invention provides an improved case by
The purpose is to improve mechanical strength and current capacity.

[0007]

In the fusible alloy type thermal fuse provided by the present invention, a fusible alloy having leads connected to both ends is housed in a case, and the leads are sealed at the ends of the case with a sealing resin. The fusible alloy type thermal fuse that is attached is characterized in that a metal body coated with an insulator is used as a case.

[0008]

In the thermal fuse having the above construction, since the case is made of a metal body, it does not break and is strong against mechanical shock, and thereby the current capacity is also improved. Also, since the case is covered with an insulating material,
It also satisfies the function as an insulating case.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fusible alloy type thermal fuse 6 of the present invention will be described with reference to FIG. The difference of this embodiment from the conventional example shown in FIG. 2 is that, instead of the ceramic cylindrical case 3, a cylindrical case 9 in which a metal cylinder 7 is covered with an insulator 8 is used. Other components, rod-shaped fusible alloy 1, leads 2 connected to both ends of fusible alloy 1,
2, the sealing resin 4, 4 for sealing both ends of the tubular case 9, and the flux around the fusible alloy (not shown) are the same as or equivalent to the conventional ones.

As the metal cylinder 7 which is the metal body used in the cylindrical case 9 which is a feature of the present invention, an iron-based tube which is advantageous in strength and cost can be used. Since the insulator 8 covering the metal cylinder 7 is exposed to a high temperature under a use environment and a spark at the time of fusing, heat resistance is required. For example, a polyimide-based, silicon-based, or fluorine-based polymer insulating material is used. Is used.

In order to assemble the fusible alloy type thermal fuse 6 of the present invention, as shown in the figure, a cylindrical case 9 having an inner surface and an outer surface of a metal tube 7 coated with an insulator 8 is prepared, and the inside thereof is prepared. This is performed by the same method as in the prior art, in which the fusible alloy 1 having the leads 2 and 2 connected to both ends is passed through and positioned, and the sealing resins 4 and 4 are poured into the openings at both ends of the cylindrical case 8 and cured.

In this assembly, the structure as described below can be adopted in order to increase the coupling force between the sealing resins 4, 4 and the case 8 and further increase the mechanical strength.

One of them is to make the both ends of the cylindrical case 9 uneven, and this processing is performed, for example, by making the metal tube 7 before being covered with the insulator 8 uneven. This has an advantage that it can be easily performed as compared with the time and effort required for producing a mold when irregularities are formed on ceramics.

The other one is to use an insulator 8 to which the sealing resin 4 is easily adhered. Since the insulator 8 can be selected from a wide range of resin materials and the like, the optimum combination can be determined. Further, in this case, if the insulator 8 is adhered to the end surface of the cylindrical case 9, the coupling force is further improved.

In the above embodiment, an example of application to the fusible alloy type thermal fuse of the axial type of the present invention has been described, but the present invention is not limited to this.
It goes without saying that the present invention can also be applied to a fusible alloy type thermal fuse such as a radial type.

[0016]

In the fusible alloy type thermal fuse of the present invention, since the case is made of a metal body as a base, the strength against impact is increased, and damage during handling such as assembling to equipment is eliminated and reliability is improved. To do. Further, due to the improvement of the impact resistance strength, the internal current is not broken even when the large current is cut off, so that the rated current capacity can be increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a fusible alloy type thermal fuse according to an embodiment of the present invention.

FIG. 2 is a sectional view of a fusible alloy type thermal fuse showing a conventional example.

[Explanation of symbols] 1 fusible alloy 2 lead 4 sealing resin 6 fusible alloy type thermal fuse 7 metal cylinder (metal body) 8 insulator 9 cylindrical case (case)

Claims (2)

[Claims] 1. A fusible alloy type thermal fuse in which a fusible alloy having leads connected to both ends is housed in a case, and the leads are sealed to the ends of the case with a sealing resin, and the fusible alloy is covered with an insulator as a case. A thermal fuse characterized by using a metal body. 2. The thermal fuse according to claim 1, wherein the insulator is made of a polyimide-based, silicon-based, or fluorine-based polymer insulating material.