JPS6314358Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature fuse that has a fuse portion through which current is passed, and which melts and interrupts an electrical circuit when the ambient temperature reaches a predetermined temperature.

FIG. 1 is a sectional view of a conventional temperature fuse (see, for example, Japanese Utility Model Publication No. 58-41697). 1st
In the figure, reference numeral 1 is a conductive cylinder with one end open, and 2 is a pellet-shaped temperature-sensitive member that is housed in the bottom wall of the cylinder 1 and melts when the ambient temperature reaches a predetermined temperature. , 3 is a lead wire inserted and held through an insulating bushing 9 fixed to the open end of the cylindrical body 1;
4 is a lead wire fixed to the bottom of the cylindrical body 1.
5 is a fixed contact formed inside the cylindrical body 1 of the lead wire 3; 6 is a movable contact that comes into contact with the fixed contact 5; 7 is a compression spring member compressed between the insulating bushing 9 and the movable contact 6. , 8 is a compression spring member which is compressed between the movable contact 6 and the temperature sensing member 2 and has a larger spring force than the compression spring member 7. In the conventional temperature fuse having such a structure, when the ambient temperature is below a predetermined temperature, the movable contact 6 is pressed against the fixed contact 5 by the compression spring member 8 as shown in FIG. 1A. In this state, the current flows from the lead wire 3 and the fixed contact 5 to the movable contact 6 to the cylinder 1 and the lead wire 4, so that the electric path is closed. However, when the ambient temperature reaches a predetermined temperature, the temperature sensing member 2 melts and the movable contact 6 no longer receives the spring force of the compression spring member 8 as shown in FIG. Arrow 9' under the spring force of 7
direction and separates from the fixed contact 5. This prevents the current from flowing from the lead wire 3 to the lead wire 4 due to the interrupted electrical path.

By the way, in this conventional example, the number of parts used is large and the structure is very complicated, which not only increases the manufacturing cost of the temperature fuse but also makes it difficult to improve the mechanical precision of assembly. Therefore, there is a high probability of manufacturing defects during assembly or failures after manufacturing, and since there are many mechanical components, there are problems with operational reliability due to mechanical deterioration.

In contrast, conventional temperature fuses have been constructed by providing a low-temperature alloy wire inside a glass tube, fitting metal caps to both ends of the glass tube, and connecting each metal cap to the corresponding end of the low-temperature alloy wire. proposed (for example, Utility Model Application No. 58-38955)
(see publication).

This temperature fuse has no mechanically moving parts, so it has excellent operation reliability, but because it uses a glass tube, it is vulnerable to external shocks. It is necessary to change the type of wire, and it is difficult to set and change the operating characteristics.If it is directly attached to the circuit board, there is a risk of damaging the glass tube, so a mounting bracket must be used. Heat conduction to the low-temperature alloy wire is indirect, resulting in poor thermal response. There are various problems such as the large number of parts and the difficulty of assembling and connecting them together.

The present invention was developed in view of the problems of the above-mentioned conventional examples, and by making the entire chip-shaped laminate, it reduces manufacturing costs, increases operational reliability, and improves mechanical performance. The object of the present invention is to provide a temperature fuse that is excellent in terms of strength, thermal response, and ease of setting the operating temperature.

In order to achieve the above object, the present invention includes a chip-type temperature fuse body made of an insulating material, and a thin film band-shaped fuse part made of a low-melting metal in the temperature fuse body. A narrow part that melts at ambient temperature is formed in the center of the fuse part, and external electrodes of membrane bodies are provided on both end faces of the temperature fuse body, and each external electrode has a narrow part that melts at ambient temperature. A temperature fuse was constructed by connecting the corresponding ends of.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 2 is a sectional view of the temperature fuse of this embodiment, and FIG. 3 is a cross-sectional view of the temperature fuse in this embodiment, and FIG.
It is a sectional view at -A. This temperature fuse 20
comprises a chip-type temperature fuse body 21 made of an insulating material. This insulating material includes ceramics such as alumina, forsterite, cordierite, and titanium oxide. The temperature fuse body 21 may have a prismatic shape, a cylindrical shape, or another shape. A fuse portion 22 made of a low melting point metal is provided within the temperature fuse body 21. The fuse portion 22 is shaped like a thin film band and is embedded inside the temperature fuse body 21 in the shape of a sandwich trench. These low melting point metals include, for example, Sn, Bi, Pb, which melts when the ambient temperature reaches a predetermined temperature.
and their alloys, Wood alloys, Lipoutz
There are alloys, Newton alloys, Rose alloys, etc. This fuse part 22 is connected to both end surfaces 2 of the temperature fuse body 21.
It is formed by extending it to 3.24. External electrodes 25 and 26 are provided on both end surfaces 23 and 24 of this temperature fuse body 21, respectively, by a method such as printing. Both end surfaces 23, 2 of the temperature fuse body 21
The fuse portion 22 facing the external electrodes 25, 2
Connected to 6. This fuse part 22 is located in the central part 2.
It is formed narrowly at 7, and wide at both ends 28, 29. As for the shape of the fuse portion 22, for example, as shown in FIG. 4, the narrow portion of the central portion 27 may be sufficiently longer than the wide portions of the opposite ends 28, 29, or as shown in FIG. Like whole 2
7, 28, and 29 may be made into only narrow width parts, and furthermore, as shown in FIG.
You can make it into multiple books like a book. Furthermore, the seventh
As shown in the figure, the narrow portion of the central portion 27 may be formed into a meandering shape. As described above, according to this embodiment, when the ambient temperature reaches a predetermined temperature, the narrow portion of the fuse portion 22 melts and can function as a temperature fuse. Furthermore, since the configuration is simple, the manufacturing cost is low, and it is easy to precisely form the fuse part 22 corresponding to the operating point as a temperature fuse. Since it is installed internally and isolated from the external environment, and has no mechanically moving parts, stable operation over a long period of time is possible.

As described above, in the present invention, the fuse part is buried inside the chip-type temperature fuse body in the shape of a sandwich bridge, and the external electrodes of the membrane body are provided at both ends of the temperature fuse body, so that each part is laminated and integrated. The structure is simple, and manufacturing costs can be reduced by manufacturing by means such as lamination or coating.

Furthermore, since there are no mechanically moving parts, stable and accurate operation over a long period of time is possible, and the reliability of operation is improved.

Furthermore, since the fuse part and the temperature fuse body are integrated, it is strong against external shocks and has high mechanical strength.

Furthermore, since the fuse part is in the form of a thin film band, by changing the width and shape of the narrow part at the center,
The operating temperature setting can be changed, and products with various operating characteristics can be easily manufactured.

In addition, since the entire structure is chip-shaped and has external electrodes on both ends, it can be directly attached to a circuit board or equipment using a conductive adhesive as a surface-mount type component, and can directly absorb the heat of the circuit board, etc. It can be mounted to receive heat, and in that case, heat is transferred directly from the temperature fuse body in contact with the circuit board to the fuse portion, resulting in good thermal response.

[Brief explanation of the drawing]

Figures 1a and b are cross-sectional views of a conventional temperature fuse before and after operation, Figure 2 is a cross-sectional view of a temperature fuse according to an embodiment of the present invention, and Figure 3 is a cross-sectional view taken along the line A-A in Figure 2.
4 to 7 are sectional views corresponding to FIG. 3 showing other modifications of the fuse portion. 20 is a temperature fuse, 21 is a temperature fuse body, 22 is a fuse part, 25 and 26 are external electrodes,
Reference numeral 27 indicates the center portion of the fuse portion 22, and 28 and 29 indicate both end portions of the fuse portion 22.

Claims (1)

[Scope of utility model registration request] It has a chip-shaped temperature fuse body made of an insulating material, and a thin film belt-shaped fuse part made of a low-melting point metal is embedded in the temperature fuse body in the shape of a sandwich trench. A narrow portion that melts depending on the temperature is formed, external electrodes of a membrane body are provided on both end faces of the temperature fuse body, and each external electrode is connected to a corresponding end of the temperature fuse body. temperature fuse.