JPH046054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to abnormal temperature detection inside equipment and devices used under high temperature conditions, such as a catalytic converter of an internal combustion engine.

Configuration of conventional example and its problems As shown in FIG. 5, a fusible metal wire 10 is fixed to two lead wires 11a, 11b,
The fusible metal part 10 is protected by an insulating tube 12, a space 13 is formed, and a powder filling 14 is
Alternatively, as shown in FIG. 6, the area around the fusible metal wire 15 fixed to the two lead wires 11a and 11b is filled with the insulating solvent 16 and fixed. This was a high-temperature fuse that was housed in a metal protective tube 1 and filled with a powdered electrical insulator 14. The former allows the fusible metal wire to be fused in a space 13 formed by an insulating tube 12 that protects the periphery of the fusible metal wire. Constant temperature rise/
Due to repeated temperature drops, it expanded and contracted significantly, and vibrations were large, causing wire breakage and other mechanical strength problems.

In addition, in the latter case, when the temperature rises to an abnormal temperature, the solvent 16, which is lower than the melting temperature of the fusible metal wire 15, first melts and diffuses into the minute voids of the powdery filler 14, forming a part of the fusible metal wire. First, in the durability test near the melting temperature of the solvent, the solvent filled and fixed in the fusible metal part begins to melt. Since it is diffused into the powdered filler, voids are formed around the fusible metal wire, which has the disadvantage that the fusible metal wire may break due to vibration and repeated heat cycles of temperature rise and fall. Furthermore, in the case of internal combustion engines, when a fusible metal wire melts at a predetermined temperature, a predetermined current is applied to issue an electrical signal to warn of abnormal temperature. The resistance degrades the given current. In order to correct this, a correction circuit is required, which also poses a problem in terms of cost. Furthermore, in terms of workability, it takes a lot of man-hours to fill and fix the area around the fusible metal wire with a solvent, and the finished shape is also unstable.

OBJECT OF THE INVENTION A high-temperature fuse comprising a fusible metal contained in a metal protective tube and filled with a powdered electrical insulating material,
It maintains vibration resistance and mechanical strength even in locations where vibration is constantly applied and where the ambient temperature repeatedly rises and falls, and it reliably fuses and electrically opens at a specified temperature between 700 and 1000°C. The present invention provides a method for manufacturing a high temperature fuse that can be integrated into a circuit.

Structure of the Invention A fusible metal with lead wires connected and fixed to both ends is housed in a heat-resistant and corrosion-resistant metal protection tube that is sealed at one end, and a powdered electrical insulating material is filled and interposed, and then the metal protection tube is closed. This is a high temperature fuse whose diameter has been reduced by swaging. The fusible metal is made into a pipe-shaped fusible metal tube with an internal space formed in advance, and connecting pipes are connected and fixed to the outer periphery of both ends of the fusible metal tube to protect the fusible metal tube from the metal. This is a method of manufacturing a high-temperature fuse by inserting the metal protection tube into a tube, filling the space within the metal protection tube with a powdered electrical insulating material, and then processing the metal protection tube to reduce its diameter.

DESCRIPTION OF EMBODIMENTS In Figures 1 and 2, 1 is a metal protection tube with excellent heat resistance and corrosion resistance, one end of which is sealed by inert gas arc welding, etc., and is made of, for example, stainless steel, Incoloy/Inconel, etc. . Reference numeral 2 is a pipe-shaped fusible metal tube, which uses not only noble metals but also general brazing materials such as silver solder and palladium solder, and alloys thereof. 3a and 3b are lead wires,
Made of stainless steel, nickel, nichrome wire, etc., which exhibit excellent heat resistance. Connection pipes 4a and 4b are made of stainless steel or the like, and the fusible metal pipe 2 and lead wires 3a and 3b are connected and fixed by spot welding or the like. 5 is a powdered electrical insulating material, for example made of magnesia and alumina powder, and metal protective tube 1
A high packing density is obtained by reducing the diameter of this metal protection tube, and the portion that contacts the periphery of the fusible metal tube 2 forms a strong cavity even after the fusible metal is melted. ing. Reference numeral 6 denotes a space provided in advance, which is formed by forming a fusible metal into a pipe shape. In FIG. 3, numeral 7 indicates a welding point for connecting and fixing the fusible metal pipe 2 and the lead wires 3a, 3b.
Welding by spot welding is simple and has good workability. Reference numeral 8 in FIG. 4 is a space formed after the fusible metal tube 2 in FIG. 2 is fused. Reference numeral 9 denotes a fusible metal formed by surface tension after fusing, and electrical conduction between lead wire 3a and lead wire 3b is interrupted by a space 8 formed after fusing the fusible metal. Further, in FIG. 2, the lead wire 3a is fixed to the metal protection tube 1 and grounded when the metal protection tube 1 is sealed. By doing so, there is no need to lead out both ends of the lead wire to the outside of the metal protection tube.

Effects of the Invention In the method of the present invention, a pipe-shaped fusible metal tube with a space formed in advance is provided, and connecting pipes are connected and fixed at both ends, so manufacturing is simple and the space can be maintained reliably. The high-temperature fuse manufactured by this method has a pipe-shaped fusible metal tube with a space formed, and when the temperature rises to an abnormal level, the volume of electrical insulating material formed around the fusible metal tube by diameter reduction is reduced. The surface tension of the fusible metal material can reliably melt the metal material and create an open circuit. Therefore, unlike the conventional example, a separate solvent is not required, and a predetermined current for generating an electric signal at the time of fusing flows immediately. In its normal state before fusing, it has high powder density due to filling with powdered electrical insulating material and diameter reduction processing, which improves vibration resistance and maintains excellent mechanical strength and durability.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view of a high temperature fuse shown as one embodiment, Fig. 2 is a partial sectional view showing another embodiment, Fig. 3 is an enlarged front view of the main part, and Fig. 4 is an enlarged sectional view of the main part. indicates the time of melting. FIGS. 5 and 6 are partial sectional views showing a conventional example. 1... Metal protection tube, 2... Fusible metal tube, 3a,
3b... Lead wire, 4a, 4b... Connection pipe,
5...Powdered electrical insulating material, 6...Space, 7...
Welding location.

Claims (1)

[Scope of Claims] 1. In a high-temperature fuse, a fusible metal is housed in a heat-resistant and corrosion-resistant metal protection tube that is sealed at one end and has lead wires connected and fixed to both ends. A pipe-shaped fusible metal tube with an internal space formed in advance, connecting pipes connected and fixed to the outer periphery of both ends of this fusible metal tube, and inserting this fusible metal tube into the metal protection tube, A method for manufacturing a high-temperature fuse, characterized in that the space inside the metal protection tube is filled with a powdered electrical insulating material, and then the metal protection tube is processed to reduce its diameter. 2. The method for manufacturing a high temperature fuse according to claim 1, wherein the fusible metal tube has lead wires connected and fixed at both ends, and one end of the lead wire is installed in a metal protection tube.