JPH0531792Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an improvement of a temperature switch.

Prior Art and Problems Conventionally, as shown in FIG. 4A, as a temperature switch using a shape memory alloy, a shape memory alloy coil 6' is provided between a movable electrode 4' and a side wall of a case. It has been proposed to provide a compression spring 5' between the movable electrode 4' and the other side wall of the case, and press the movable electrode 4' against the lead conductor 2b' against the spring force of the shape memory alloy coil 6'. (3' is case 1'
and the lead conductor 2b'). The martensitic transformation temperature of the shape memory alloy is set as the operating temperature of the temperature switch, and when heated to this temperature, the shape memory alloy coil 6' restores to its original shape as shown in FIG. 4B. As the movable electrode 4' separates from the lead conductor 2b', the amount of compression of the spring 5' increases. The compressive stress F of the spring 5' in this state is larger than the stress f before the switch is activated, and the length of the shape memory alloy coil in its original shape is L, and the spring constant of this coil is k,
If the length of the lead wire is l, the distance d between the lead conductor 2b' and the movable electrode 4' in FIG. 4B is d=L(1-kF)-l, and the shape memory alloy If the time required for the coil to restore its original shape, that is, the time required for alloy transformation, is t, then the detachment speed V of the movable electrode is given by: V=(L-l)-LkF/t-.

The compressive stress F of the spring 5' in the operating state shown in FIG. 4B is larger than the compressive stress f of the spring 5' before the temperature switch is activated in FIG. The detachment speed V of the movable electrode, which is represented by the equation, is slow, which is a problem for high voltage applications (if V is small, restriking is likely to occur).

An object of the present invention is to increase the detachment speed of the movable electrode.

Configuration of the invention In other words, the temperature switch according to the invention has the first
A second lead conductor is introduced into a metal case having a lead conductor from one side wall of the case, insulated from the case,
A magnetic movable electrode is brought into contact with the tip of the second lead conductor, a shape memory alloy coil is interposed between the movable electrode and one side wall of the case, and the movable electrode is moved against the spring force of the coil. second by magnetic force
This structure is characterized by being press-contacted to the tip of the lead conductor.

Description of examples The present invention will be explained below with reference to the drawings.

In FIG. 1, 1 is a metal case;
A lead conductor 2a is provided. 2b is a second lead conductor, which is introduced into the metal case 1. An insulating spacer 3 is interposed between the second lead conductor 2b and the metal case 1. 4 is a movable electrode having magnetism, which is a composite of a magnetic plate 41 and a conductive plate 42. 5 is a magnetic material fixed to the case 1. 6 is a coil manufactured from a shape memory alloy by utilizing martensitic transformation, and is shortened to a length slightly longer than the protruding length l of the second lead conductor 2b. This set coil remembers its original shape (see Figure 2) and returns to this original shape at the operating temperature of the temperature switch.

The movable electrode 41 or magnetic material 5 having magnetism
One or both of them are magnetized to form a magnet, and therefore, an attractive magnetic force acts between them, causing the movable electrode 4 to resist the compressive stress of the coil 6 and move the second lead conductor 2b. It is pressed against the tip.

When the temperature switch is not operating, the current flows from the second lead conductor 2b to the conductive plate 42 of the movable electrode 4.
The flow follows the path of shape memory alloy coil 6 → metal case 1 → first conductor 2a.

When the operating temperature of the temperature switch is reached, the restraint of the coil is released, the coil returns to its memorized original shape, and the movable electrode 4 moves to the second position as shown in FIG.
It separates from the lead conductor 2b and performs an off operation. Assuming that the movable electrode 4 is brought into pressure contact with the lead conductor 2b with a force f as in the conventional example before the switch is operated in FIG. 1, the above-mentioned attractive magnetic force is f. However, after the switch is activated in FIG. 2, the attracting magnetic force is
f' is smaller than the above f. Therefore, the desorption rate V' of the movable electrode is given by V'=(L-l)-Lkf'/t- by replacing F in the first equation with f', and as mentioned above, Since f'<f, F>f, F≫f', and V' in the second equation can be made larger than V in the first equation.

In the above, as shown in FIG. 3A, the magnet 4
It is also possible to plate the surface of the lead conductor 2b with a magnetic material 7 such as iron or nickel so as to apply an attractive magnetic force between the lead conductor 1 and the lead conductor 2b. Further, as shown in FIG. 3B, the movable electrode 42 can be used as a sliding electrode that slides on the case 1, and the constant current path can be made into the path shown by the arrow. Furthermore, the lead conductor 2
The magnet 410 is configured to apply a repulsive force to the magnet 41 in order to increase the contact pressure between the movable electrode 42 and the magnet 410.
It is also possible to provide In addition, Figures 3A to 3
In FIG. B, parts with the same reference numerals as in FIG. 1 indicate the same components as in FIG. 1.

Effects of the Invention As mentioned above, in the temperature switch according to the present invention, instead of pressing the movable electrode to the lead conductor with a spring, unlike the conventional switch using a shape memory alloy coil, the movable electrode is attached to the lead conductor by an attractive magnetic force. Since the movable electrode is in pressure contact with the lead conductor, the detachment speed of the movable electrode from the lead conductor can be increased. Therefore, even when used under high voltage, restriking can be well prevented, which is advantageous for high voltage applications.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a temperature switch according to the present invention, Fig. 2 is an explanatory diagram showing the operating state of the switch of the present invention, and Figs. 3A and 3B are explanatory diagrams showing other embodiments of the present invention. 4A is an explanatory diagram showing a conventional example, and FIG. 4B is an explanatory diagram showing the operating state of the conventional example. In the figure, 1 is a metal case, 2a is a first lead conductor, 2b is a second lead conductor, 4 is a movable electrode,
41 is a magnetic plate, 5 is a magnetic material, and 6 is a shape memory alloy coil.

Claims (1)

[Scope of utility model registration request] A second lead conductor is introduced from one side wall of the case into a metal case having a first lead conductor, insulated from the case, and a magnetic movable electrode is brought into contact with the tip of the second lead conductor, and the movable electrode and the case are connected. A shape memory alloy coil is interposed between the movable electrode and the side wall, and the movable electrode is pressed against the tip of the second lead conductor by an attractive magnetic force directed toward the side wall of the case, against the spring force of the coil, and heated. A temperature switch characterized in that the shape memory alloy coil is restored to its original shape and the movable electrode is separated from the second lead conductor.