JPS61147423A - 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 the Invention The present invention relates to a high-temperature heater that can be applied to detect abnormal temperatures inside a catalytic converter of an internal combustion engine used under high-temperature conditions.

Conventional technology A conventional high temperature heater will be explained with reference to FIG.

The fusible metal wire 13 is connected to a pair of metal lead wires 14a.

14b and stored in the metal protection tube 12, the metal lead wire 141Li is grounded to the metal protection tube 12, and the fusible metal wire 1
3 parts are protected by an insulator tube 16 to form a space part 17,
It had a structure in which powdered electrical insulating material 18 was filled and fixed.

Problems to be Solved by the Invention This conventional high-temperature fuse makes it possible to blow out the fusible metal wire by utilizing the space inside the insulator tube that protects the periphery of the fusible metal wire. However, as in internal combustion engines, where the operating conditions are high and the temperature is constantly rising and falling, the expansion and contraction caused by the temperature difference inside and outside the metal protection tube is significant, and vibrations are constantly added, resulting in stress caused by these stresses. There was a major problem with mechanical strength, such as the fusible metal wire breaking due to the breakage of the fusible metal wire. The present invention solves these problems by providing vibration resistance and expansion resistance even in locations where vibration is constantly applied at high temperatures, and even under conditions where the ambient temperature repeatedly rises and falls.
The purpose is to create a low-cost, high-temperature fuse that maintains mechanical strength such as tensile and compressive stress that occurs during contraction, and that can reliably blow out the fusible metal wire at a predetermined temperature in the event of an abnormal temperature rise. It is something to do.

Means for Solving the Problem In order to solve this problem, the present invention provides a coil spring shape for a fusible metal wire having a grounded metal lead wire inside a metal protection tube, and protects the internal components with an insulator tube. The opening of the metal protective tube is completely sealed to prevent oxygen, water, and moisture from entering from the outside, and the tip of the metal tube is heated to a temperature slightly lower than the melting point of the fusible metal. The insulator tube is held by heating and applying a plurality of (2) heat caulks, or by circumferentially caulking the notch groove provided in the insulator tube.

Effect: With this configuration, under conditions of repeated tensile and compressive stresses that occur when expanding and contracting due to temperature rise and fall, the fusible metal wire in the shape of a coil spring can expand and contract within the insulator tube, eliminating any problems such as wire breakage. . Furthermore, vibration resistance is maintained because the insulator tube is held by heat caulking and circumferential caulking of the metal protection tube. In particular, the plurality of thermal caulks are caulked at high temperatures, so even if the metal protection tube is placed at high temperatures, no gaps with the insulator tube occur due to thermal expansion, and the insulator tube is completely held.

The same applies to notched grooves provided on the outer periphery of the insulator; providing the notched grooves in locations where the temperature does not rise comparatively and caulking is more effective.

Embodiment FIGS. 1, 2, 3, and 4 are sectional views, external views, and partial sectional views according to embodiments of the present invention.
In the embodiments shown in ) and (b), 1 is a metal protective tube made of a material such as stainless steel, Incoloy, or Inconel, which has excellent heat resistance and corrosion resistance. 2 is a fusible metal wire in the shape of a coil spring, and uses not only noble metals but also general brazing materials such as silver solder, palladium solder, gold solder, and alloys thereof. 3a, 3b Hfi[IJ-G wire, stainless steel,
It is made of nichrome, nickel wire, etc., and is fixed to the fusible metal wire 2 by welding. 4 is an insulator tube having through holes 6a and sb for protecting the fusible metal wire 2 on one side and the metal lead wire 3b on the other side, and is made of a sintered body of alumina, magnesia, silicon nitride, or the like. Further, in the embodiment shown in FIG.
is held. In the embodiment shown in FIG. 3, 7 is a powdered electrical insulating material filled and fixed in the gap between the metal protection tube 1 and the insulator tube 4, and is made of powders such as magnesia, alumina, and silicon nitride. In the embodiment shown in FIG. 4, reference numeral 8 denotes a circumferential caulking portion in which a notched groove 9 portion provided on the outer periphery of the insulator tube in the metal protection tube 1 is caulked.

Effects of the Invention As described above, the present invention maintains its mechanical strength even under conditions of constant vibration and repeated expansion and contraction due to rising and falling temperatures, and can withstand long-term high-temperature durability tests. It can also die out. Further, when the temperature rises to an abnormal level, the coil spring-shaped fusible metal wire melts within the insulator tube at a predetermined temperature, and is reliably fused by the surface tension of the fusible metal material to create an open circuit. Furthermore, since it has a metal protection tube and a grounded structure, it is easy to work with and is very cost effective.

[Brief explanation of the drawing]

FIG. 1 (al, (bl) is a partial cross-sectional view of a cross-sectional view showing an embodiment of the present invention, and FIG. 5 is a partial cross-sectional view showing a conventional example. 1. ... Fusible metal wire, 12a, 12b ... Metal lead wire, 1
3... Melted reed part, 14"°"°°° insulator tube,
16... Space portion, 16... Powdered electrical insulating material.

Claims (4)

[Claims] (1) A coil spring-shaped fusible metal wire having a pair of metal lead wires grounded and housed in a metal protection tube with excellent heat resistance and corrosion resistance, one through hole to protect the fusible metal wire, and the other to the metal A high temperature fuse that is protected by an insulator tube with a through hole that is in close contact with a lead wire, and the opening of the metal protection tube is completely sealed. (2) A high temperature fuse according to claim 1, wherein the tip of the metal protection tube is thermally caulked in a plurality of pieces at a temperature slightly lower than the melting point of the fusible metal. (3) A high-temperature fuse according to claim 1, wherein a powdered electrical insulating material is filled and fixed in a gap between a metal protection tube and an insulator tube that protects a fusible metal wire. (4) A high-temperature fuse according to claim 1, wherein a groove is provided on the outer periphery of the insulator tube, and the metal protection tube is circumferentially caulked to the groove.