JP2001052580A - Thermally-actuated switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized and thin-type thermally-actuated switch which allows relaxing effect of external stress upon a fixing part of each terminal to a bimetal piece or fixed contact even when external force is applied to the terminal led out of a case so as to reduce effect of displacement of the bimetal piece or fixed contact, and having a stable temperature characteristic. SOLUTION: This thermally-actuated switch has an insulation case 1; a first terminal 2 installed in the insulation case 1, fixedly attached with a fixed contact 3 on one side and led out of the insulation case 1 on the other side; a bimetal piece 5 fixedly attached with a moving contact 6 on one side, inverting according to a temperature to contact with and separate from the fixed contact 3; and a second terminal 4 installed in the insulation case 1, fixedly attached with the other side of the bimetal piece 5 on one side and led out of the insulation case 1 on the other side. Opening parts 2c, 4c are formed between the fixing part of the first terminal 2 to the fixed contact 3 and the other end side led out of the insulation case 1, and/or between the fixing part of the second terminal 4 to the bimetal piece 5 and the other end side led out of the insulation case 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermally responsive switch, and more particularly, to a switch structure for inverting a movable contact and opening and closing an electrical contact by the thermal response of a bimetal piece.

[0002]

2. Description of the Related Art A thermally responsive switch comprises a movable electrode having a movable piece of a thermally responsive element (bimetal) in which a plurality of metals having different coefficients of thermal expansion are bonded to each other, and a fixed electrode which forms a normally closed contact circuit together with the movable electrode. An electrode is provided and is connected to a circuit of the electric device to protect the electric device.

That is, a thermally responsive switch connected to a circuit of an electric device has a structure in which a switch contact is opened by an inversion action of a bimetal when an excessive current flows through the electric device or when an ambient temperature becomes abnormally high. Therefore, the power supply to the electric device is cut off.
Then, when the power supply to the electric equipment is cut off, the ambient temperature decreases, and the bimetal is automatically reset, and the switch contact is closed again to restart the power supply. It is possible to operate in a temperature range.

A conventional thermally responsive switch is disclosed in Japanese Unexamined Patent Publication No.
No. 306316. FIGS. 11 and 12 show the structure of this conventional thermoresponsive switch. FIG. 11 is a perspective view of the thermally responsive switch, and FIG. 12 is a sectional view of the same.

In the figure, a thermally responsive switch comprises a fixed terminal 12 having a fixed contact 11 at one end, and a bimetal piece 14 having a movable contact 13 at its tip which is moved toward and away from the fixed terminal 12 by heat. A movable terminal 15 supported at one end is provided in a cover 16 and a case 17 made of synthetic resin.

The other end of the fixed side terminal 12 and the other end of the movable side terminal 15 are respectively led out of the case 17 to form connection terminal portions 18 and 19. 19 is a planar portion. These connection terminal portions 18 and 19 are led out from side surfaces of both ends of the case 17. Further, the connection terminal portions 18 and 19 of the fixed side terminal 12 and the connection terminal portion 19 of the movable side terminal 15 face each other so as to face each other.
Are bent along the bottom surface of the case 17.
The fixed side terminal 12 and the movable side terminal 15 are embedded and fixed at the bottom of the case 17.

As a result, the positional accuracy between the fixed terminal 12 and the movable terminal 15 is improved, and the positional accuracy between the fixed contact 11 and the movable contact 13 is significantly improved. As a result, the contact pressure between the fixed contact 11 and the movable contact 13 becomes constant, and the temperature at which the snap action of the bimetal piece 14 occurs when the temperature rises, that is, the variation in the operating temperature is prevented. .

In the buried portion of the movable terminal 15,
Multi-stage bent portions 15a, 15a are formed in the case 17, and by forming the bent portions 15a, 15a, the influence of terminal bending when an external force is applied to the movable-side terminal 15 during mounting. Has been suppressed.

[0009]

The above-mentioned conventional thermoresponsive switch is used, for example, mounted between electrodes of a battery such as a portable telephone, but the mounting space is limited due to the layout with the battery. Therefore, there is a demand for extremely small and thin switches having a thickness of 1.5 mm or less, which is the outer shape of the switch. Therefore, there is an urgent need to provide a thermally responsive switch using a thermally responsive element (bimetal) that can be made small and thin and has stable temperature characteristics. However, in the above-described structure of the conventional thermally responsive switch, the connection terminal portions 18 and 19 which are the other end portions of the movable terminal 15 and the fixed terminal 12 are used.
Is configured to be led out of the case 17 directly from the fixed portion between the bimetal piece 14 and the movable terminal 15 or the fixed portion between the fixed contact 11 and the connecting terminal portion 18 during mounting. When external force is applied to 19,
With the bending of the connection terminals 18 and 19 in the plate thickness direction, the position of the tip of the bimetal piece 14 to which the movable contact 13 is fixed and the position of the fixed contact 11 are displaced, and the bimetal piece 14 is displaced. There is a problem that the temperature characteristics of the piece 14 are affected.

In the buried portion of the movable terminal 15,
In order to suppress the influence of terminal bending, the case 17
Since the bent portions 15a are formed in multiple stages therein, the thickness is increased by the amount of the bent portions 15a, and there has been a problem that the size and thickness of the switch cannot be reduced.

Therefore, the present invention solves the above-mentioned problem, and even when an external force is applied to the connection terminal portion led out of the case, the external stress of each terminal portion and the fixing portion of the bimetal piece or the fixed contact is fixed. It is an object of the present invention to provide a small-sized and thin heat-responsive switch which can reduce the influence, reduce the influence of the displacement of the bimetal piece and the fixed contact, and stabilize the temperature characteristics.

[0012]

In order to solve the above-mentioned problems, in the present invention, as a first means, an insulating case, a fixed contact is fixed to one end of the insulating case, and the other end is fixed to the insulating case. The first led out of the insulating case
And a movable contact is fixed to one end, and a bimetal piece that is inverted according to temperature and can be brought into contact with and separated from the fixed contact is attached to the insulating case, and the other end of the bimetal piece is fixed to one end. And the other end side has a second terminal led out of the insulating case, and a fixed portion of the fixed contact of the first terminal and the other end side led out of the insulating case. And / or an opening is formed between the fixed portion of the bimetal piece of the second terminal and the other end of the second terminal that is led out of the insulating case. .

As a second means, the opening is
It is formed on a center line passing through the fixing portion in the longitudinal direction of the first and / or second terminal.

As a third means, the opening is
The width of the opening is formed to be larger than the width of the fixing portion in the width direction of the first and / or second terminals.

As a fourth means, the opening is
It is characterized in that it is formed near the fixing portion of the first and / or second terminal.

As a fifth means, the opening is
The first and / or second terminals are provided with a slope at a portion including the opening, and the slope is embedded in the insulating case. It is characterized by being attached.

As a sixth means, a thickness of 1.5 mm
An insulating case having the following outer shape, a first terminal and a second terminal embedded in the insulating case, a fixed contact fixed to one end of the first terminal, and a second terminal. A bimetal piece fixed to one end side; and a movable contact fixed to the other end side of the bimetal piece, inverted in accordance with temperature, and capable of coming into contact with and separating from the fixed contact. In the vicinity of the fixed portion with the bimetal piece, an opening is formed which is formed by a cut orbiting around the outer periphery of the fixed portion, and the second terminal is provided with an inclined portion in a portion including the opening. The inclined portion is embedded and attached to the insulating case.

As a seventh means, the bimetal piece has a dome-shaped inverted portion at the center, and one end of the bimetal piece excluding the inverted portion and one end of the second terminal are connected to each other. Are fixed by a linear welded portion in the longitudinal direction of the bimetal piece.

As an eighth means, a linear projection is formed in one end side of the second terminal in the longitudinal direction, and the welding portion is provided on the projection.

[0020]

1 to 10 show an embodiment of the present invention. 1 to 9 show the structure of a thermally responsive switch according to a first embodiment of the present invention. FIG. 1 is an exploded perspective view of the thermally responsive switch, FIG. 2 is a plan view thereof, and FIG. 4 is a plan view of a bimetal piece to which a movable contact is fixed, FIG. 5 is a front view thereof, FIG. 6 is a plan view of an insulating case in which terminals are embedded, FIG. 7 is a cross-sectional view thereof, and FIG. FIG. 9 is a front view of the terminal, and FIG.

In the drawing, an insulating case 1 is formed of an insulating material such as a synthetic resin in a box shape having an open upper surface. Terminals, which will be described later, are provided on the inner bottom of the insulating case 1, and one end of each terminal is led out from both sides of the insulating case 1. Also,
At the center of the inner bottom surface of the insulating case 1, there is provided a support projection 1a projecting hemispherically from the inner bottom surface.

The first terminal 2 is made of a conductive metal material such as phosphor bronze and is formed in a flat plate shape. At one end of the first terminal 2 is provided a mounting hole 2a to which a fixed contact 3 made of silver tin oxide or the like is fixed. At the other end of the first terminal 2, the insulating case is provided. A connection terminal portion 2b is provided which is led out from the side surface portion 1 and is connected to a circuit of another electric device.

The first terminal 2 has a mounting hole 2a to which the fixed contact 3 is fixed and a connection terminal 2b.
A wide opening 2c near the mounting hole 2a.
Is provided. The opening 2 c is formed on the center line passing through the mounting hole 2 a in the longitudinal direction of the first terminal 2, and the width of the opening 2 c in the width direction of the first terminal 2. Is formed so as to be larger than the width of the mounting hole 2a. Further, the opening 2c is formed by cutting so as to go around the outer periphery of the mounting hole 2a.

The first terminal 2 is provided with an inclined portion 2d at a portion including the opening 2c, and a mounting hole 2 to which the fixed contact 3 is fixed via the inclined portion 2d.
The configuration is such that the portion a is connected to the connection terminal portion 2b. When the first terminal 2 is attached to the insulating case 1, the inclined portion 2 d is embedded and attached to the inner bottom of the insulating case 1.

The second terminal 4 is also formed of a conductive metal material such as phosphor bronze in a plate shape. A projecting portion 4a is formed on one end side of the second terminal 4 by biasing with a press or the like, and the projecting portion 4a is a welded portion for fixing one end of a bimetal piece described later. At the other end of the second terminal 4, there is provided a connection terminal 4b which is led out from the side surface of the insulating case 1 and is connected to a circuit of another electric device.

The second terminal 4 has a wide opening 4c near the protrusion 4a between the protrusion 4a for fixing a bimetal piece to be described later and the connection terminal 4b. Is provided. The opening 4c is formed on the center line passing through the protrusion 4a in the longitudinal direction of the second terminal 4, and in the width direction of the second terminal 4,
The width of the opening 4c is formed to be larger than the width of the protrusion 4a. The opening 4c is
The cutout is formed so as to orbit around the outer periphery of the protrusion 4a.

The second terminal 4 is provided with an inclined portion 4d at a portion including the opening 4c, and a projecting portion 4a to which a bimetal piece to be described later is fixed via the inclined portion 4d. , And the connection terminal portion 4b. When the second terminal 4 is attached to the insulating case 1, the inclined portion 4 d is embedded and attached to the inner bottom of the insulating case 1.

As described above, by providing the openings 2c and 4c in the first and second terminals 2 and 4,
For example, during transportation or mounting, the connection terminal portions 2b, 4
Even if an external force is applied to the connection terminals 2b and a stress such as bending in the thickness direction is applied to the connection terminal portions 2b and 4b, the stress is interrupted by the openings 2c and 4c.
The influence of external stress on a portion fixed to a bimetal piece or a movable contact, which will be described later, and a portion fixed to the fixed contact 3 can be reduced, and the influence on the displacement of each contact can be reduced. Thus, a thermally responsive switch having stable temperature characteristics can be obtained.

The inclined portions 2d and 4d are provided in portions including the openings 2c and 4c, and the inclined portions 2d and 4d are embedded in the inner bottom portion of the insulating case 1 and attached. In addition, the embedded portions of the second terminals 2 and 4 can be lengthened, and can be firmly fixed without increasing the outer shape of the insulating case 1, so that downsizing can be achieved. Further, it is possible to prevent flux from entering the inside during soldering.

The bimetal piece 5 is formed by laminating two types of metal materials having different coefficients of thermal expansion, for example, a high expansion material made of a material having a high electric resistance and a low expansion material made of a material having a low electric resistance in a plate shape. It is formed by joining. A movable contact 6 made of silver tin oxide or the like, which comes into contact with or separates from the fixed contact 3, is fixed to one end of the bimetal piece 5 serving as a free end by a method such as laser welding. The projection is fixed to the projection 4a provided on the second terminal 4 by a method such as laser welding. In this case, the connecting portion between the second terminal 4 and the other end of the bimetal piece 5 is not the entire surface but a partial connection only at the protruding portion 4a. When the inversion operation is performed, the operation characteristics are not impaired.

In the center of the bimetal piece 5,
Inflated dome-shaped reversing portion 5 for promoting reversing action
a is formed, and by forming the inversion portion 5a, the inversion operation of the bimetal piece 5 according to the temperature characteristic, that is, the temperature, can be surely performed.

The cover 7 is formed in a substantially plate shape from an insulating material such as a synthetic resin, is mounted on the opening of the insulating case 1, and is provided inside the insulating case 1. The influence of dust, gas, and the like on the second terminals 2 and 4, the bimetal piece 5, the movable contact 6, the fixed contact 3, and the like is prevented.

Next, the operation of the above-described thermoresponsive switch of the present invention will be described. At a normal temperature and a normal use temperature, the movable contact 6 and the fixed contact 3, which are arranged to face each other, are in contact with each other and the contacts are in an ON state. If the temperature rises from this state for some reason, the inversion section 5a provided on the bimetal piece 5 to which the movable contact 6 is fixed performs an inversion operation according to the rise in temperature. At this time, the movable contact 6 fixed to the bimetal piece 5 is
, And is separated from the fixed contact 3, so that the contact is turned off. In this case, the swelling portion of the inverted portion 5a of the inverted bimetal piece 5 is inverted, and projects in the direction of the fixed contact 3, that is, the direction of the inner bottom surface of the insulating case 1.

Further, when the temperature falls from this state and returns to the normal temperature, the inversion portion 5a of the bimetal piece 5 returns to the inversion in response to the decrease in the temperature, and the direction opposite to the direction of the fixed contact 3 is reversed. As the movable contact 6 comes into contact with the fixed contact 3, the contact is turned on and the contact returns to the initial state.

In the above-described structure of the thermally responsive switch according to the present invention, a dome-shaped reversing portion is provided at the central portion of the bimetal piece 5 to promote a reversing action when reversing according to temperature. Since the layer 5a is formed, the reversing operation is reliably performed. Note that the support projection 1a is provided on the inner bottom surface of the insulating case 1. Therefore, when the temperature is lowered, if the reversing portion 5a returns without being reversed due to a gradual temperature change (cooling), the reversing portion 5a contacts the support protrusion 1a. The contact makes it possible to keep the contact between the movable contact 6 and the fixed contact 3 in a separated state, thereby preventing chattering of the contact between the movable contact 6 and the fixed contact 3 when the contact is reversed again when the temperature rises. Has become.

FIG. 10 shows the structure of a thermally responsive switch according to a second embodiment of the present invention. FIG. 10 is an exploded perspective view showing a bimetal piece, a movable terminal and a fixed terminal. FIG.
The same components as those described in FIG. 9 to FIG.

In this case, the difference from the first embodiment is that the structure of the projecting portion 4e serving as a welding portion for fixing one end of the bimetal piece 5 provided on the second terminal 4 is slightly different. It is a point. That is, the protrusion 4 provided on the second terminal 4 of the thermoresponsive switch according to the second embodiment of the present invention.
In the configuration of e, a linear protrusion 4e is formed in the longitudinal direction of the second terminal 4, and one end of the bimetal piece 5 excluding the reversing part 5a, 5 is provided with a welded portion which is fixed linearly in the longitudinal direction.

According to the configuration of the second embodiment of the present invention, the direction of the welded portion for fixing the bimetal piece 5 is
Since the length of the bimetal piece 5 is set in the longitudinal direction, the inversion portion 5 of the bimetal piece 5 that performs an inversion operation according to the temperature is provided.
a and the welding portion and the reversing portion 5 are not hindered.
Since the distance from the a can be reduced, the length of the bimetal piece 5 can be reduced, and the size of the entire switch can be reduced. In addition, since the welded portion for fixing the bimetal piece 5 is formed on the second terminal 4 side, it is not necessary to perform the uneven thickness processing on the bimetal piece 5 by pressing or the like. Since the influence of processing variations of the portion 5a can be suppressed to a small extent, a thermally responsive switch having stable temperature characteristics can be obtained.

[0039]

As described above, the thermally responsive switch according to the present invention can be provided between the fixed portion of the fixed contact of the first terminal and the other end led out of the insulating case, and / or An opening is formed between the fixed portion of the bimetal piece of the terminal No. 2 and the other end of the insulating case that is led out of the insulating case. Even if a stress such as bending in the plate thickness direction is applied to the connection terminal, this stress is interrupted by the opening, so that the fixed portion with the bimetal piece or the movable contact or the fixed contact with the fixed contact The effect of external stress on the portion can be reduced, the influence on the displacement of each contact portion can be reduced, and a thermally responsive switch with stable temperature characteristics can be obtained.

Further, since the opening is formed on the center line passing through the fixing portion in the longitudinal direction of the first and / or second terminals, the effect of external stress on the fixing portion is surely reduced. be able to.

The opening is formed in the width direction of the first and / or second terminals so that the width of the opening is larger than the width of the fixing portion. Since the connection with the fixing portion is completely interrupted, the influence of external stress on the fixing portion can be further reliably reduced.

Further, since the opening is formed in the vicinity of the fixed portion of the first and / or second terminals, the effect of external stress on the fixed portion can be easily reduced with a simple structure. it can.

Further, the opening is cut so as to orbit around the outer periphery of the fixing portion, and the first and / or the second terminal is provided with an inclined portion at a portion including the opening.
Since this slope was embedded in the insulating case and attached,
The buried portions of the first and second terminals can be lengthened,
Since the insulating case can be firmly fixed without enlarging the outer shape, it is possible to reduce the size of the switch and prevent the flux from rising at the time of soldering.

Further, an insulating case having an outer shape having a thickness of 1.5 mm or less, a first terminal and a second terminal embedded in the insulating case, and fixed to one end of the first terminal. A fixed contact; and a bimetal piece having a movable contact fixed to one end of the second terminal. The second terminal has a portion near the fixed portion with the bimetal piece and in accordance with the outer periphery of the fixed portion. An opening formed by a notch that goes around is formed, and the second terminal is provided with an inclined portion in a portion including the opening, and the inclined portion is buried in the insulating case and attached. Since the influence of external stress on the fixed part can be reduced, the external size can be reduced and the thickness can be reduced, and a thermally responsive switch that can be mounted in an extremely narrow space between the electrodes of a battery (battery). Can be obtained.

Further, the bimetal piece has a dome-shaped inverted portion in the center, and one end of the bimetal piece excluding the inverted portion and one end of the second terminal are linearly formed in the longitudinal direction of the bimetal piece. Since the fixing is performed at the welded part, the distance between the welded part and the inverted part can be reduced without hindering the inversion operation of the inverted part of the bimetal piece that performs the inversion operation according to the temperature. The size can be reduced, and the size of the entire switch can be reduced.

Further, since a linear projection is formed in one end side of the second terminal in the longitudinal direction and a welded portion is provided on the projection, it is necessary to perform the uneven thickness processing of the bimetal piece by a press or the like. In addition, since the influence of the processing variation of the reversal part on the bimetal piece can be suppressed to a small extent, a thermally responsive switch having stable temperature characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a thermally responsive switch according to a first embodiment of the present invention.

FIG. 2 is a plan view showing the same thermally responsive switch of the present invention.

FIG. 3 is a sectional view showing the same thermally responsive switch of the present invention.

FIG. 4 is a plan view showing the bimetal piece of the present invention with the movable contact fixed thereto.

FIG. 5 is a front view showing the bimetal piece of the present invention with the movable contact fixed thereto.

FIG. 6 is a plan view showing an insulating case of the present invention in which terminals are also buried.

FIG. 7 is a cross-sectional view showing an insulating case of the present invention in which terminals are also buried.

FIG. 8 is a plan view showing the same hoop-shaped terminal of the present invention.

FIG. 9 is a front view showing the same hoop-shaped terminal of the present invention.

FIG. 10 is an exploded perspective view showing a bimetal piece, a movable terminal, and a fixed terminal according to a second embodiment of the present invention.

FIG. 11 is a perspective view showing a conventional thermally responsive switch.

FIG. 12 is a sectional view showing a conventional thermally responsive switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulation case 1a Support projection 2 First terminal 2a Mounting hole 2b Connection terminal 2c Opening 2d Inclined portion 3 Fixed contact 4 Second terminal 4a, 4e Projection 4b Connection terminal 4c Opening 4d Inclined portion 5 Bimetal Piece 5a reversing part 6 movable contact 7 cover

Claims (8)

[Claims] 1. An insulating case, a first terminal attached to the insulating case, having a fixed contact fixed to one end and having the other end led out of the insulating case, and a movable contact at one end. Is fixed to the insulating case, and a bimetal piece which is inverted according to temperature and can be brought into contact with and separated from the fixed contact, and the other end of the bimetal piece is fixed to one end and the other end of the insulating case is fixed to the insulating case. A second terminal extending outwardly, and between a fixed portion of the fixed contact of the first terminal and the other end side outwardly extending from the insulating case; and / or the second terminal. An opening is formed between the terminal of the bimetal piece and the other end of the terminal extending outward from the insulating case. 2. The thermally responsive switch according to claim 1, wherein the opening is formed on a center line passing through the fixing portion in a longitudinal direction of the first and / or second terminal. . 3. The opening is formed such that the width of the opening is larger than the width of the fixing portion in the width direction of the first and / or second terminals. 3. The thermally responsive switch according to claim 1, wherein 4. The thermally responsive switch according to claim 1, wherein said opening is formed in the vicinity of said fixing portion of said first and / or second terminal. . 5. The opening is formed by cutting so as to orbit around the outer periphery of the fixing portion, and the first and / or the opening are formed.
The second terminal is provided with a slope at a portion including the opening, and the slope is embedded in the insulating case and attached. The thermally responsive switch as described. 6. An insulating case having an outer shape with a thickness of 1.5 mm or less, a first terminal and a second terminal embedded in the insulating case, and fixed to one end of the first terminal. A fixed contact, a bimetal piece fixed to one end of the second terminal, and a bimetal piece fixed to the other end of the bimetal piece;
A movable contact which is inverted in accordance with temperature and which can be brought into contact with and separated from the fixed contact; a cut in the second terminal in the vicinity of the fixed portion with the bimetal piece and orbiting along the outer periphery of the fixed portion; Wherein the second terminal is provided with a slope at a portion including the opening, and the slope is embedded in the insulating case and mounted. 7. The bimetal piece has a dome-shaped inverted portion in the center, and one end of the bimetal piece excluding the inverted portion and one end of the second terminal are connected to the longitudinal direction of the bimetal piece. 7. The thermally responsive switch according to claim 6, wherein the switch is fixed by a linear weld in the direction. 8. The heat responsive device according to claim 7, wherein a linear projection is formed in one end of the second terminal in a longitudinal direction, and the welding portion is provided on the projection. switch.