JPS5916237A - 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 Industrial Field of Application This invention is applied to detecting abnormal temperatures inside equipment and devices used under high temperature conditions, such as catalytic converters of internal combustion engines.

The structure of the conventional example and its problems As shown in Fig. 9, two lead wires (2
0B) (20b) and housed in the metal protection tube (1), the fusible metal wire a9 portion is protected with the insulating tube (2I) to form a space (221), and the powdered filling (23) Also, as shown in Figure 10, the two lead wires (20B) (20b) and the fixed fusible metal wire (24) are surrounded by an electrically insulating solvent (24). The powdered filling (23
) was a high-temperature fuse.

The former made it possible to fuse the fusible metal wire by using the space in the insulating tube that protected the fusible metal wire, but the operating conditions were high temperatures like internal combustion engines, and the temperature was constantly rising and falling. There were problems with mechanical strength, such as repeated expansion and contraction, large vibrations, and the space around the fusible metal wire, which caused the fusible metal wire to break.

Regarding the latter, the area around the fusible metal wire is filled and fixed with an electrically insulating solvent, and when the temperature rises to an abnormal temperature, the solvent that is lower than the melting temperature of the fusible metal wire melts first. The fusible metal wire is fused and cut by the voids in the fusible metal wire portion that are formed by diffusing into the micro voids of the powder filling.

With this configuration, first of all, in durability tests near the melting temperature of the solvent, the electrically insulating solvent filled and fixed in the fusible metal wire begins to melt and diffuses into the powder filling, making the fusible A void is formed around the metal wire portion, and the fusible metal wire may break due to vibration and repeated heat cycles of temperature rise and fall. In addition, when a fusible metal wire melts at a predetermined temperature, such as in an internal combustion engine, a predetermined current is applied to issue an electrical signal warning of abnormal temperature, but the above-mentioned solvent diffused into the powder filling Degradation of a given current due to the insulation resistance of In order to correct this, a correction circuit is required, which increases the cost and improves workability. Filling and fixing the fusible metal wire part with an electrically insulating solvent takes a lot of man-hours, and the finished shape is unstable. There are drawbacks.

Purpose of the Invention In a high-temperature fuse consisting of a fusible metal contained in a metal protective tube and filled with a powdered electrical insulating material, 1. Furthermore, even under usage conditions where the ambient temperature repeatedly rises and falls, the fusible metal will reliably melt at a predetermined temperature of 700 to 1000°C while maintaining its vibration resistance and mechanical strength, making it electrically open. The present invention provides a high temperature fuse that can be integrated into a circuit.

Structure of the Invention After inserting lead wires from both ends of a pipe-shaped fusible metal tube with an internal space formed in advance and fixing them at predetermined positions, an insulator tube is press-fitted onto the outer periphery of the fusible metal tube, and the metal Store it in a protective tube and seal the tip by welding.
This is a high-temperature fuse constructed by connecting one lead wire to a metal protection tube, filling it with powdered electrical insulating material, and then reducing the diameter of the metal protection tube. '5] The molten metal tube is melted at a predetermined temperature, and the molten metal is poured into the inner volume of the insulator tube that is in close contact with the outer periphery of the molten metal tube, which is larger than the volume of the molten metal tube that forms the space. The surface tension is used to fuse and cut off the electrical continuity between the two lead wires.

Description of Examples In Figures 1 and 2, (1) is a metal protection tube with excellent heat resistance and corrosion resistance, made of stainless steel, Incoloy, Inconel, etc., and whose tip is welded and sealed by inert gas arc welding or the like. ing.

(2) is a pipe-shaped fusible metal tube that forms an internal space, and uses noble metals, silver solder, baradium wax, general solder materials, and alloys thereof. (3a), (3b
) is a lead wire made of stainless steel, nickel, nichrome, etc., which has excellent heat resistance and corrosion resistance, and is a fusible metal tube (2
) and are firmly connected by spot welding, etc. (4) is a fusible metal tube (an insulator tube press-fitted closely to the outer periphery of 21, made of alumina or magnesia, and completely fired. (5) is the lead wire (3a) and (3b). This is the space inside the fusible metal pipe after the metal pipes have been connected and fixed. (6) is a powdered electrical insulating material filled in the modern protection 1', and is made of magnesia or alumina powder. (7) is the fusible metal pipe. metal tube (
2 Lead wire (3B) pushed into the specified position within the island (
3b) and the fusible metal tube (21), using spot welding etc. (8) is the cylindrical hole in the insulator tube into which the fusible metal tube (21 is press-fitted), (9) is the welded part where the lead wire is This is a through hole to be inserted.In this example, it is melted at a predetermined temperature and inserted into the inner volume of the insulator tube that is in close contact with the outer periphery of the fusible metal tube, which is larger than the volume of the fusible metal tube forming the space. ,
The surface tension characteristic of fusible metals causes them to melt and cut off electrical conduction.

In Figures 3 and 4, (a) is an insulator tube A that is press-fitted into the outer periphery of a fusible metal tube, (ill is an insulator tube B,
This insulator tube B is longer than the insulator tube A. These insulator tubes A and B are made of alumina, magnesia, etc., and are completely fired. t12+ is a gap formed after the insulator tube A (10) and the insulator tube B (tU) are press-fitted into the fusible metal tube.

(13115+ is a cylindrical hole in the insulator tube into which the fusible metal (2) is press-fitted, and (141(lb+ beam) is a through hole into which the single lead wire is inserted.

A fusible metal tube made of precious metals and their alloys is melted at a predetermined temperature to form an internal space.A long length fixed to the drawer lead wire side that forms an internal volume larger than the volume of the fusible metal tube. Inside the insulator tube, there is a layer that uses the surface tension characteristics of the fusible metal to melt and break down the powdered electrical insulation material filled in the gaps between the insulator tubes, completely blocking electrical continuity. to form. In addition, after the fusible metal pipe is fused, it is isolated with a powdered electrical insulating material.
There is no danger of reinduction even under vibration or shock.

Further, in FIGS. 5 to 8, (17) is the fusible metal after being fused at a predetermined temperature. α& is the space in the insulator tube formed after the fusible metal tube is fused, and the lead wire (3a)
(3b) is in an open state to cut off electrical continuity.

Effects of the invention When a pipe-shaped Machikinajima tube with a space formed in advance is heated to an abnormal temperature, it melts in the inner volume of the insulator tube at a predetermined temperature and is fused due to surface tension characteristics, causing a gap between the lead wires. Cuts off continuity. The fusible metal tube is press-fitted tightly into the insulator tube, and its outer periphery is filled with powdered electrical insulating material, so it has excellent vibration and mechanical strength, and the inner circumferential surface of the insulator tube has no unevenness. Because the metal has a high finish and has a high finish, the fusible metal exhibits high fluidity when melted, which has the effect of ensuring reliable cutting.

Further, since a solvent as in the conventional example is not required, there is an effect that a predetermined current for generating an electric signal is immediately passed when the remelted metal pipe is melted.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main parts showing an embodiment of the present invention, Fig. 2 (a) is an enlarged front view of the fusible metal and the insulator tube, (b) is a cross-sectional view of the insulator, and Fig. 3 is the other one. A sectional view of main parts showing an example,
Figure 4 (a) is an enlarged view of fusible metal and insulator A-A in Figure 5.
7 is an enlarged sectional view of the main part of the fusible metal pipe shown in FIG. 3 after being fused, FIG. The figure is a sectional view of the main parts of a conventional high temperature fuse. (1)... Metal protection tube, (2)... Fusible metal tube, (3
a) (3b)...Lead wire, (4)...Insulator tube, (5)...Space (6)...Powdered electrical insulating material,
σ2: Gap agent Patent attorney Oshima -Ko

Claims (2)

[Claims] (1) Lead wires are inserted and fixed from both ends into a pipe-shaped fusible metal tube that has an internal space, and an insulator tube is press-fitted onto the outer periphery of the fusible metal tube to protect it from heat resistance.
It is housed in a metal protection tube with excellent corrosion resistance, the tip is sealed by welding, and one lead wire is grounded to the metal protection tube,
A high temperature fuse made by reducing the diameter of a metal protective tube after filling it with powdered electrical insulation material. (2) As insulator tubes to be press-fitted onto the outer periphery of the fusible metal tube, a pair of insulator tubes are press-fitted from both sides of the fusible metal tube,
A high temperature fuse according to claim 1, wherein a gap is provided between the insulator tubes.