JPS6244369B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a thermal fuse comprising a cylindrical case containing fusible pellets.

This type of temperature fuse is constructed as shown in FIG. That is, in a cylindrical conductive case 2 to which the first lead wire 1 is connected, a lumpy soluble pellet 3 and a movable conductive plate 4 are placed via a hold spring 5, and the movable conductive plate 4 and the second A ceramic insulator 7 supporting a lead wire 6 is disposed via a push spring 8. A sealing layer 9 coated with a hardening resin such as epoxy resin is provided on the outer end of the insulator.

In such a temperature fuse, since the soluble pellets 3 are solid at room temperature, a constant distance is maintained between the soluble pellets 3 and the movable conductive plate 4, and the first lead wire 1 is connected to the first lead wire 1 through the case 2 etc. Second lead wire 6
A conductive path is formed between the two. However, when the fusible pellet 3 melts due to an abnormal temperature rise, the hold spring 5 changes from a compressed state to an expanded state, so the movable conductive plate 4 moves to the left in FIG. 1 due to the force of the push spring 8. It separates from the tip 6a of the second lead wire 6, and the conductive path is cut off.

By the way, conventionally, in the process of manufacturing such a temperature fuse, each component is assembled into the case 2, a sealing layer 9 made of a curable resin is provided on the outer end of the insulator, and then placed in a thermostatic oven at a high temperature (80 to 110℃). The sealing layer 9 is cured by heating at a temperature of
Since the particles escape outward along the outer circumferential surface, bubbles or minute holes are generated in the sealing layer 9, which tends to cause problems such as a decrease in withstand voltage characteristics and poor appearance.

Furthermore, in Japanese Patent Application Laid-Open No. 53-6871, an element is housed in a space inside a case, a lead wire is led out from the opening of the case through an insulating bushing, and a two-component type Before applying an insulating sealant such as epoxy resin, the entire case is heated to expand the air inside the case and a fluid insulating sealant is applied. A temperature fuse is attached to the insulating sealant, and as the air inside the case cools and contracts, the insulating sealant is sucked into a minute gap between the case and the insulating bushing or between the insulating bushing and the lead wire and solidified. A manufacturing method is disclosed.

However, in this method, an insulating sealant such as a two-component epoxy resin is sucked between the case and the bushing, which are in a high temperature state, so the insulating sealant is heated between them and dissolved therein. The moisture and air that had been present are released, and since the insulating sealant is then thermally crosslinked at a high temperature (lower than the melting temperature of the temperature fuse), decomposition products accompanying crosslinking are also released. There was a problem that air bubbles and minute holes were formed in the sealing portion.

The present invention has been made in order to solve this problem, and it is an object of the present invention to provide a method of manufacturing a temperature fuse in which bubbles and the like are not generated in the sealing portion.

In the manufacturing method of the present invention, parts such as the fusible pellet 3, the hold spring 5, the movable conductive plate 4, the push spring 8, and the insulator 7 supporting the second lead wire 6 are sequentially stored in the conductive case 2. death,
After bringing the opening periphery 2a of the conductive case into close contact with the outer edge of the insulator, the inside of the conductive case is dried and dehumidified under high temperature, and under this condition, the outer edge of the insulator, the opening periphery of the conductive case, and the second lead wire are connected. Temporarily seal each abutting part with a fast-curing adhesive. Thereafter, a curable resin is applied on the outer end of the insulator and the abutting portion to form a sealing layer.

As the fast-curing adhesive, an instant adhesive such as Aron Alpha (trade name), which hardens in a few seconds, or a fast-curing adhesive, such as Araldite (trade name), which hardens in a few minutes, is used.

As mentioned above, a temporary seal was provided on the outer end of the insulator exposed from the open end of the conductive case during drying, and then a sealing layer of curable resin was provided. It has a two-layer structure: a temporary sealing layer made of a fast-curing adhesive that does not generate gas or decomposition gas, and therefore does not generate bubbles, etc., and a sealing layer made of a curable resin. Even if bubbles or the like are generated in the seal layer due to decomposition products, the dielectric strength of the layer will not be reduced. Further, since the curing time of the temporary seal is extremely short compared to that of a normal curable resin, the workability is hardly reduced.

Next, examples of the present invention will be described.

Example 1 As shown in FIG. 2, each component was housed in a conductive case 2, and the opening periphery of the conductive case was brought into close contact with the outer edge of the insulator 7, and then placed in a thermostatic oven to maintain the temperature.
The inside of the case 2 is dried by heating at 100 to 110°C for 30 to 60 minutes, and under this heated state, the contact parts 10 and 11 between the outer end of the insulator, the periphery of the opening of the conductive case, and the second lead wire 6 are heated. Make a temporary seal with Aron Alpha (product name). Thereafter, an epoxy resin was applied onto the outer end of the insulator to form a sealing layer 9, and this sealing layer was cured.

The temperature fuse thus obtained had no bubbles or minute holes in the sealing layer, and completely passed the specified withstand voltage test (withstanding 1.5 KV for 1 minute immediately after the pellet fusing test).

In addition, by baking an insulating coating such as fluorocarbon resin, Teflon, formal resin, etc. on the outer surface of the push spring, the withstand voltage between it and the tip of the second lead wire can be improved, making it suitable for higher voltage applications. It is possible to manufacture temperature fuses of

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a temperature fuse, and FIG. 2 is a simplified diagram for explaining the method of the present invention. DESCRIPTION OF SYMBOLS 1...First lead wire, 2...Conductive case, 3...Fusible pellet, 4...Movable conductive plate, 5...Hold spring, 6...Second lead wire, 7...Insulator, 8...Push spring, 9...Seal Layer, 10, 11... contact portion.

Claims (1)

[Claims] 1 Inside a cylindrical conductive case with a first lead wire connected to one end, a fusible pellet, a hold spring,
After storing the movable conductive plate, push spring, and insulator supporting the second lead wire in order, and bringing the opening periphery of the conductive case into close contact with the outer edge of the insulator, the inside of the conductive case was dried at high temperature. Below, the contact parts between the outer end of the insulator, the periphery of the opening of the conductive case, and the second lead wire are temporarily sealed with a fast-curing adhesive, and then the outer end of the insulator and the contact parts are sealed with a fast-curing adhesive. 1. A method for manufacturing a temperature fuse, which comprises coating a thermoplastic resin to form a sealing layer.