JPS6356661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature fuse that protects equipment by cutting off an electric circuit when a predetermined temperature is reached. By replacing the element with
To provide a temperature fuse that is simple in structure, reliable in operation, easy to manufacture, and inexpensive.

It is known that in so-called shape memory alloys, phase transformation occurs inside the metal by heating and cooling near the transformation point, and when the shape changes, a strong transformation force is generated at the same time. In other words, if this alloy is shaped into a desired memorized state and then heat-treated to memorize that shape, it is difficult to deform it at a temperature below its transformation point. However, when it reaches a transformation point (transformation temperature) through subsequent heating, it returns to its original memorized shape with a strong transformation force. Alloys with this property are generally Ti.
It is made of Ni alloy or Cu, Zn, x (x is a metal element that affects the properties of the memory alloy), and the physical properties of the alloy can be varied depending on the mixing ratio.

The present invention mainly applies the property of shape change at the transformation point of this shape memory alloy to a temperature fuse, and will be explained below with reference to the drawings while comparing with a conventional example.

Figure 1 shows an example of a conventional temperature fuse.
1 is a cylindrical case made of metal, etc.; 2 and 3 are leads that are inserted from both ends of the cylindrical case 1 and fixed internally facing each other with their ends maintaining an insulating interval; The lead 2 is electrically connected to a cylindrical connector 5, and current flows from one lead 2 to the connector 5 and then to the other lead 3. 6 is a low melting point alloy 4,
It is a non-conductive, temperature-sensitive material that melts at a temperature higher than 4', and has a hole in the center through which the lead 2 passes. Reference numeral 7 denotes a spring inserted into the cylindrical case 1, in which the low melting point alloys 4, 4' are melted, and
When the temperature-sensitive substance 6 melts, the connector 5 is connected to the lead 3.
It acts in the direction of pulling it away from. Connector 5 here
The bottom part 8 has a flange, which has the function of operating the connector 5 at the same time as the spring 7 operates, and also has the function of preventing a concentrated load on the temperature-sensitive substance 6. Reference numerals 9 and 10 are insulators for fixing and insulating the leads 2 and 3, and one of the insulators 10 is provided with a groove 11 for positioning the spring 7. 12, 12' are the cylindrical case 1 and the insulators 9, 1
It is a heat-resistant resin that fixes and seals 0 and leads 2 and 3.

In the above configuration, when the ambient temperature reaches a predetermined temperature, the temperature-sensitive substance 6 rapidly melts and the spring 7
As a result, the connector 5 is separated from the lead 3, and the electric path from the lead 3 to the lead 2 is cut off. At this time, the low melting point alloys 4, 4' are already in a molten state before the temperature sensitive substance 6 melts, and as the temperature sensitive substance 6 melts, the leads 2, 3 are cut off as described above.

In the conventional temperature fuse constructed as described above, its operating temperature is precisely determined by the temperature sensitive material 6. For example, the temperature is 99°C for 2.4 diaminotoluene, 115°C for acetanilide, 126°C for succinimide, and 139°C for P-toluenesulfonamide. By the way, some of this type of temperature-sensitive material has hygroscopic properties, such as the above-mentioned succinimide, and when it absorbs moisture, its melting temperature changes and it does not operate at the expected normal operating temperature. According to experiments, there are cases where it operates at a temperature several degrees lower.

Temperature fuses are intended to prevent various dangers and protect the equipment due to abnormal temperature rises that may occur during use of the equipment, and cannot tolerate changes in operating temperature due to moisture absorption over time. For this reason, in the conventional example, the cylindrical case 1, the insulators 9, 10, and the leads 2, 3 are fixed with heat-resistant resins 12, 12' to prevent the temperature-sensitive material from absorbing moisture.
And it's sealed. The work for this sealing requires careful management, such as surface treatment of each part, application of heat-resistant resin, preliminary drying, baking, and temperature and time control during baking. In addition, temperature-sensitive substances are made by molding powdered raw materials, and care must be taken in the management of moisture absorption, weighing, molding conditions, etc. during production as described above.

In order to eliminate the drawbacks of the conventional example as described above, the present invention obtains a temperature fuse by using a temperature sensing element made of a shape memory alloy instead of a temperature sensitive material. This will be explained with reference to FIG.

In the figure, cylindrical cases 14 and 15 made of metal or the like are rod-shaped leads inserted from both ends of the cylindrical case 13. They face each other so as to maintain an interval, and the low melting point alloy 16,1
A cylindrical connector 1 that is movable in the axial direction of the leads 14 and 15 via 6' and has a flange 17' at one end.
7, and the current is configured to flow from one lead 14 through a connector 17 to the other lead 15. Reference numeral 18 denotes a coil-shaped spring inserted into the cylindrical case 13 and externally attached to the connector 17.
The free end of 8 abuts against the collar 17' of the connector 17,
It acts in a direction to separate the connector 17 from the lead 15.

Reference numeral 22 denotes a coil-shaped temperature sensing element made of a shape memory alloy, which is placed inside the cylindrical case 13 and is sheathed on the other lead 14 with both ends not fixed to the connector 17 and the insulator 19. When it comes to the third
As shown in the figure, the shape is memorized to be in a compressed state, and at room temperature it is in an expanded state as shown in Fig. 2, supporting the connector 17 by balancing the force of the spring 18. There is. Note that this transformation temperature is set higher than the melting temperature of the low melting point alloys 16, 16'.

19, 20 are the leads 14, 1 in the cylindrical case 13.
It is an insulator for fixedly insulating 5. 21,2
1' is a heat-resistant resin that fixes the cylindrical case 13, insulators 19, 20, and leads 14, 15;
Cylindrical case 13, insulators 19 and 20, and lead 1
Needless to say, if a means for mechanically fixing 4 and 15 to each other is employed, these heat-resistant resins 21 and 21' become unnecessary. In the above, the coil-shaped temperature sensing element 22 made of a shape memory alloy is shaped into a compressed state in which the electric circuit is interrupted as shown in FIG.
It retains its shape and is heat treated to memorize its shape.

In the above configuration, when the ambient temperature reaches a predetermined temperature, the temperature sensing element 22 made of a shape memory alloy changes its shape to a compressed state as shown in FIG. 3 due to the nature of shape change at its transformation point, and the connector 17 is separated from the lead 15 by the spring force of the spring 18, and the electric path from the lead 14 to the lead 15 is cut off. At this time, since the low melting point alloys 16 and 16' have a melting point lower than the transformation temperature of the temperature sensing element 22, they are already in a molten state before the temperature sensing element 22 changes its shape to a compressed state, and the temperature sensing element 2
The leads 14 and 15 are severed as described above by the force of the spring 18 due to the change in shape of the lead 2.

As described above, according to the present invention, a temperature-sensitive element made of a shape memory alloy is used instead of the temperature-sensitive material seen in the conventional example, and the shape change of the temperature-sensitive element at the transformation temperature causes the spring to Since the cylindrical connector that electrically connects the rod-shaped leads is separated from one lead by force, operation is reliable and it is free from changes in operating temperature due to moisture absorption of conventional temperature-sensitive materials. The old problems disappeared, and as a result,
The work of sealing the cylindrical case, insulator, and lead can be eliminated. In addition, since the conventional temperature-sensitive material is simply replaced with a temperature-sensing element made of a shape memory alloy, the structure is simple, and it is possible to provide a low-cost temperature fuse with good productivity. Rod-shaped leads are fixed to both ends of the case so that the ends are facing each other with an insulating gap inside, and the leads are electrically connected using a cylindrical connector that can move freely in the axial direction of the leads. This allows the temperature fuse to be made smaller, and since the terminals of the leads are located at both ends of the cylindrical case, there are no restrictions when connecting to the internal wiring of the device or arranging the temperature fuse. Never. Moreover, since the coil-shaped temperature-sensing element made of a shape memory alloy has both ends unfixed and is sheathed on the other lead, the temperature-sensing element is attached to a connector or an insulator that fixes a pair of leads. Therefore, there is no need for special processing means or man-hours for fixing this temperature-sensitive element, and yields are high and process control is easy.
As a result, various excellent effects can be achieved, such as being able to produce reliable temperature fuses at low cost.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional temperature fuse, Figure 2 is a cross-sectional view of a conventional temperature fuse.
The figure is a sectional view of a temperature fuse according to an embodiment of the present invention, and FIG. 3 is a sectional view of the temperature fuse after operation. 13...Cylindrical case, 14,15...Lead,
17... Connector, 18... Spring, 22...
Temperature sensing element.

Claims (1)

[Claims] 1. A pair of leads fixed internally at both ends of a cylindrical case so that the ends are facing each other so as to maintain an insulating interval, and a device that electrically connects the pair of leads and is movable in the axial direction of the leads. a cylindrical connector, a coiled spring that urges the connector in a direction to pull it away from one lead, and a coiled spring that supports the connector against the spring and deforms into a compressed state at a predetermined temperature. A temperature fuse consisting of a coil-shaped temperature sensing element made of a shape memory alloy, with both ends of the temperature sensing element left unfixed and externally wrapped around the other lead.