JPH0262813B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a thermosensor.

Traditionally, thermosensors have been manufactured using thermocouples and thermistors, which are often used to accurately sense temperatures over a wide range of temperatures.However, thermocouples and thermistors are expensive, and the sensing output is limited An amplifier is always required to operate an alarm or the like with a voltage as low as a few millivolts, which makes thermosensor devices expensive. There is a strong demand for low cost especially in those used in large quantities, such as thermosensors for detecting the temperature of exhaust gas purification catalysts in automobiles. Therefore, the present invention is a method of manufacturing a thermosensor that senses a predetermined temperature by melting a fusible wire, in order to provide a method of manufacturing a thermosensor that makes the thermosensor inexpensive.

Hereinafter, the present invention will be described in detail based on specific embodiments shown in the accompanying drawings. FIG. 1 shows an outline of a high temperature warning device for an automobile exhaust gas purification catalyst using the thermosensor of the present invention. A thermosensor faces a catalyst purifier 1 through which exhaust gas flows, and a warning light 2 and a battery 3 are wired to the thermosensor. As shown in FIGS. 2 and 3, the thermosensor accommodates two fusible wires 5 in a metal tube 4 and fills it with a powder insulator 6. The metal tube 4 is made of stainless steel, parakeet, or the like. The fusible wire 5 is made of an alloy such as copper-zinc or silver-copper so as to melt at a predetermined temperature, and since the sensing temperature in the catalyst purifier 1 is about 850°C, copper has a melting point of 1083°C and copper has a melting point of 419°C. An appropriate amount of zinc is mixed with zinc and set to melt at that temperature, and an appropriate alloy is selected for sensing any temperature. As the powder insulator 6, magnesium oxide, aluminum oxide, or the like is used. The manufacturing method of this thermosensor involves inserting a fusible wire 5 into a molded body made of powdered insulator 6 in advance, and tightly fitting the molded body into a metal tube 4 to improve insulation performance. The metal tube 4 is squeezed over its entire length, the compact is crushed, and the metal tube 4 is filled with the insulator 6 in powder form. Note that in squeezing the metal tube 4, a normal die is used to reduce the diameter of the metal tube 4. The long metal tube 4 produced as described above is cut to a predetermined length, one end of the metal tube 4 is closed by welding, etc., and one fusible wire is exposed at the other end. 5
is connected to the electric wire 8, and the other fusible wire 5 is connected to the metal tube 4.
Connect to the inner wall of the building and ground. Although we have described an example in which there are two fusible wires 5, one in Fig. 4 and three in Fig. 5 have been described.
Books, the 7 books shown in Figure 6, and other cases are manufactured in the same manner.

This manufacturing method will be explained with reference to FIGS. 7 to 12.

FIGS. 7 and 8 show a molded body 11 preformed from a powder insulator 6, with two through holes 12 formed therein.

Next, as shown in FIG. 9, the fusible wire 5 is
It is inserted into the through holes 12 of a plurality of molded bodies 11.

Subsequently, as shown in FIG. 10, the fusible wire 5
A plurality of molded bodies 11 are inserted into the metal tube 4 and are tightly fitted into the metal tube 4.

Furthermore, as shown in FIG.
Squeeze over the entire length.

Subsequently, as shown in FIG. 12, the squeezed metal tube 4 is cut into a predetermined length. One end of the metal tube 4 is closed with a lid 7 by welding or the like. The end of the fusible wire 5 is attached to the metal tube 4, excluding the powder insulator 6 at the other end of the metal tube 4.
Connect to the interior wall.

Next, the operation of this thermosensor will be described. When the installed location of the thermosensor reaches a predetermined temperature, the fusible wire 5 melts, penetrates the powder insulator 6, and becomes electrically conductive with other fusible wires 5 or the inner wall of the metal tube 4. Then, the warning light 2 lights up and issues an alarm. 3 to 6 show the state in which the fusible wire 5 melts and penetrates into the powder insulator 6. When the fusible wire 5 is melted, it is always electrically connected to another fusible wire 5 or to the inner wall of the metal tube 4 at some point in the axial direction. In addition, when the metal tube 4 is squeezed, cracks tend to occur in the direction in which the fusible wire rods 5 are lined up, making it easier to conduct electricity in that direction. It is better for the fusible wire 5 to have a large cross-sectional area, and for the metal tube 4, a metal tube with small thermal expansion, such as a parakeet, is suitable.

As described above, in the present invention, a fusible wire is inserted into a molded body formed of a powder insulator 6 in advance, and the molded body into which the fusible wire is inserted is tightly fitted into a metal tube 4. , the metal tube 4 is squeezed over its entire length, cut into a predetermined length, one end of the metal tube 4 is closed with a lid 7 by welding, etc., and one fusible wire 5 exposed at the other end is This is a manufacturing method for a thermosensor that is manufactured by connecting it to the inner wall of a metal tube 4. Direct conduction is achieved by melting the fusible wire, so there is no need for relays or amplifiers to operate alarms, etc., making it extremely inexpensive, especially in large quantities. Suitable as a manufacturing method for thermosensors for commercial products. Further, the thermosensor manufactured by this manufacturing method is conductive at the time of fusing no matter which direction it is placed, and there is no need to consider the direction of the arrangement, making it easy to use as any thermosensor. Furthermore, since the thermosensor manufactured by this manufacturing method is simply a powdered insulator and a fusible wire housed in a metal tube, it can be formed very small (for example, a metal tube diameter of 3 mm) and has good vibration resistance. . Furthermore, the thermosensor manufactured by this manufacturing method is extremely easy to manufacture because it is manufactured by cutting a metal tube containing a fusible wire into an appropriate length.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an outline of a thermosensor manufactured by the manufacturing method of the present invention installed in an automobile exhaust gas catalytic purifier, and Figure 2 is a specific example of the thermosensor manufactured by the present invention. FIG. 3 is a cross-sectional view of FIG. 2, FIG. 4, FIG. 5, and FIG. 6 are cross-sectional views of other embodiments, and FIG. 7 is a vertical cross-sectional view of the molded body. Figure 8 is a side view of Figure 7, Figure 9 is a vertical cross-sectional view of the molded body with the fusible wire inserted through it, and Figure 10 is the molded body with the fusible wire inserted through it, tightly packed into a metal tube. FIG. 11 is a vertical cross-sectional view of the fitted state, FIG. 11 is a vertical cross-sectional view of the metal tube shown in FIG.
FIG. 2 is a longitudinal cross-sectional view of a thermosensor manufactured by cutting the metal tube of FIG. 1 into a predetermined length. 6... Powder insulator, 11... Molded body, 5... Fusible wire, 4... Metal tube, 7... Closed lid.

Claims (1)

[Claims] 1. The fusible wire 5 is inserted into a molded body 11 formed of powdered insulator 6 in advance, and the molded body 11 into which the fusible wire 5 is inserted is tightly fitted into the metal tube 4. The metal tube 4 is squeezed over its entire length, cut into a predetermined length, one end of the metal tube 4 is closed by welding, etc., and one fusible wire 5 exposed at the other end is attached to the inner wall of the metal tube 4. A method for manufacturing a thermosensor that is connected to a .