JPS5916238A - High temperature fuse - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to abnormal temperature detection inside equipment and devices used in high temperature conditioners, such as catalytic converters of internal combustion engines.

The structure of the conventional example and its problems Figure 6 1 As shown, a fusible metal wire (111) is fixed to two lead wires (121N) (12b), and a metal protection tube (
1) Store the fusible metal wire (111 part) in the insulating tube (13)
to form a space ([41) and a powdery filling (I
5), or as shown in Fig. 7, the fusible metal 06) fixed to the two lead wires (12a) (12b) is surrounded by electrically insulating material. Solvent (1
It was a high-temperature fuse that was filled and fixed with 7), housed in a metal protective tube (1), and fixed with powdered filler α5).

The former makes it possible to fuse the fusible metal wire by using the space in the insulating tube that protects the area around the fusible metal wire, but the use conditions are high and the temperature is constantly rising and falling, such as in internal combustion engines. If repeated expansion and contraction occur and the vibrations are large, there is a large space around the fusible metal wire, which causes the wire to break, resulting in major drawbacks in mechanical strength. In addition, in the latter case, an electrically insulating solvent is filled and fixed around the fusible metal wire, and when the temperature rises to an abnormal temperature, the solvent whose melting temperature is lower than the melting temperature of the fusible metal wire melts first, forming a powder filling. It diffuses into the microscopic voids of objects and fuses the fusible metal wire with the voids formed around the fusible metal wire, but in the case of durability tests near the melting temperature of the solvent, The electrically insulating solvent that is fixed in the fusible metal wire part begins to melt and diffuses into the powder filling, creating a void around the fusible metal wire, which causes vibration and repeated temperature rises and falls. Heat cycles may cause the fusible metal wire to break. In addition, when a fusible metal wire melts at a predetermined temperature, as in an internal combustion engine, a predetermined current is applied to issue an electrical signal warning of abnormal temperature, but the insulation of the solvent diffused into the powder filling The resistance degrades the given current. In order to correct this, there is a problem that a correction circuit is required, which increases the cost. Furthermore, there were also difficulties in workability (here too, the fusible metal wire portion was filled and fixed with an electrically insulating solvent, which required a lot of man-hours and the finished shape was unstable).

Purpose of the Invention A high-temperature fuse consisting of a fusible metal housed in a metal protective tube and filled with powdered electrical insulating material is used in a place where vibration is constantly applied, and where the ambient temperature repeatedly rises and falls. 70 while maintaining vibration resistance and mechanical strength even under
The present invention provides a high-temperature fuse that reliably melts the fusible metal at a predetermined temperature of 0 to 1000°C and creates an electrical open circuit.

Structure of the invention Inside a metal protection tube with excellent heat resistance and corrosion resistance that seals one end (
This pipe-shaped fusible metal tube is stored in which a space with a volume larger than the volume of the fusible metal is formed in advance during melting.
A lead rope is connected to this, and activated electrically insulating brazing flux is applied to the outer periphery of the = J' molten metal pipe or filled in the space, and then powdered electrical insulating material is filled. This is a high-temperature fuse made by reducing the diameter of a protective metal material by swaging. The fusible metal tube, which melts at a predetermined temperature, is reliably fused to the internal volume of the electrical insulating material by surface tension, and the electrical continuity between the two lead wires is cut off. J' The melt cutting of the molten metal is made more reliable.

DESCRIPTION OF THE EMBODIMENTS In FIG. 1, (1) is a metal protective tube whose one end is sealed by inert gas arc welding or the like, and is made of a metal with excellent heat resistance and corrosion resistance, such as stainless steel and Incoloy/Inconel. (2) is a fusible metal tube in the shape of a knob, and uses not only noble metals but also general brazing materials such as silver solder and parasedation solder, and alloys thereof. (3B)
, (3b) are lead wires made of stainless steel, nickel, nichrome wire, etc., which exhibit excellent heat resistance. (1), (4
b) is a connecting pipe made of stainless steel etc., which connects the fusible metal pipe (2) and the lead wires (3B), (3b).
The connection is fixed by welding etc. (5) is a powdered electrical insulating material made of magnesia and alumina powder, etc., and is filled into the metal protection 1 (1), and a high packing density is obtained by diameter reduction processing, and it is packed around the fusible metal tube (2). The contact portion forms a strong cavity after the fusible metal is melted. (6) is a space provided in advance in the fusible metal pipe, and is formed by shaping the fusible metal into a pipe shape. (
7) is the fusible metal pipe (2) and lead wires (3B), (3b)
This is the welded part that is firmly connected. (3) is a soluble metal - (2
) is an electrically insulating brazing flux that has a melting temperature slightly lower than that of the fusible metal coated on the outer periphery of the wire. In FIGS. 3 and 4, (9) is a brazing flux coated on the outer peripheral end of the fusible metal tube (2).

If a material with a melting temperature slightly lower than the melting temperature of the fusible metal is used, the surface tension characteristics of the fusible metal when it is fused can be further improved. At a predetermined temperature, a space larger than the volume of the fusible metal tube formed when the fusible metal tube is melted can be melted and cut due to the surface tension characteristics of the fusible metal material, thereby interrupting conduction of the lead wire. For electrically insulating brazing, flux is applied to part or all of the outer periphery of the fusible metal tube (this coating or filling the inside of the fusible metal tube), so the melting of the flux increases the surface tension of the fusible metal material. It has an excellent effect of improving the durability.Furthermore, by coating the flux and filling it into the fusible metal tube, there is no effect of the insulation resistance of the flux, so the specified current can be passed in an emergency.Also, the durability Since the material has a high powder density due to filling with powdered electrical insulating material and diameter reduction processing, it is possible to improve vibration resistance and maintain mechanical strength.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main part showing an embodiment of the present invention, Fig. 2 is an enlarged front view of a fusible metal tube, Fig. 3 is a sectional view of the main part showing another embodiment, and Fig. 4 is the same. FIG. 5 is an enlarged front view of the molten metal pipe, and FIGS. 6 and 7 are enlarged front views showing other embodiments of the molten metal pipe.
The figure is a sectional view of a main part showing a conventional example. (1)... Metal protection tube, (2)... Fusible metal tube, (
3B). (3b)...Lead wire, (5)...Powdered electrical insulating material, (6)...Space, (8 bar 91 (lf)...Flux agent for electrical insulation brazing Person Patent Attorney Oshima - Public Figure 1 Figure 3

Claims (1)

[Claims] (1) A body wire made of fusible metal is connected in advance to a heat-resistant and corrosion-resistant metal protective tube sealed at one end, and activated electrically insulating brazing flux is applied as described above. Applying it to the outer periphery of the fusible metal pipe or filling the space,
A high-temperature fuse made by reducing the diameter of the metal protection tube after filling it with a powdered electrical insulating material.