JP2005235446A - Safeguard - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safeguard with little voltage loss, of which a detecting part detecting excessive current or temperature with the use of a heat-responsive element is downsized. <P>SOLUTION: A fixed contact 7 connected to a first terminal 3 and a movable plate 9 having a movable contact 8 at a position opposite to the fixed contact 7 are arranged inside a housing 2. The movable plate 9 has a tip of a bimetal 15 engaged with a folded claw part 9a of its own tip. A resistive element 16 is arranged between the bimetal 15 and the movable plate 9. The resistive element 6, of a thin sheet member full of elasticity with insulation treatment applied, is arranged in connection with a second terminal 4 and a third terminal 5. When a current exceeding a certain value flows between the second terminal 4 and the third terminal 5, the resistive element 16 radiates heat to have the bimetal 15 inverted, which closes the fixed contact 7 and the movable contact 8 to form a contact circuit between a first contact 3 and a second contact 4, and with this current, a latching relay device 24 of a tripping unit 22, for instance, is driven to open a normally closed switch 23 of a power source line 21. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a safety device that detects excessive current and temperature using a thermal actuator.

Conventionally, as a safety device that detects excessive current and temperature, as a thermally responsive breaker, a conductive wire is wound around a thick bimetal plate, and the bimetal is displaced by Joule heat generated by the wire. It is known that the current is cut off by directly removing the latch of the switching unit. (For example, refer to Patent Document 1.)
Also known is a current fuse that cuts off a current by fusing a fusible body with Joule heat generated by an energizing current. (For example, see Patent Document 2.)
JP 2000-340093 A ([Summary], FIG. 1) JP 2000-315991 ([Summary], FIG. 1)

  However, the breaker that directly cuts off the energized current as in the technique of the above-mentioned Patent Document 1 has a structure in which the detection portion directly energizes the power supply current with respect to the excessive current. The size is also increased and the structure is complicated, and thus there are restrictions on installation.

In addition, since the thermo-responsive element is operated by Joule heat generated by the resistance of the energized portion, the detection portion is also directly the energized portion, so that resistance is generated in the energized portion, and this energizing circuit is a low voltage circuit In some cases, voltage loss was caused.
In addition, as in the technique of Patent Document 2, the configuration in which the fusible body is blown by Joule heat generated by the resistance of the energized portion is used when the fusible body is blown so that the large current can be stably flowed. Therefore, there is a problem that there are many restrictions on the detection part and the mounting part. In addition, once melted, there is a problem that workability is poor because it must be replaced with a new soluble material to restore it.

  In view of the above-described conventional situation, an object of the present invention is to provide a safety device in which a detection unit is downsized and voltage loss is small.

  First, a safety device according to a first aspect of the present invention is a safety device configured to close a contact circuit when a thermally responsive element senses a temperature rise around the element and reverses the direction of warping, and a fixed contact connected to the first terminal. A movable plate having a movable contact at a position facing the second terminal and connected to the second terminal, a thermally responsive element that opens the contact circuit when in a normal warping state, the thermally responsive element and the movable plate, A resistor portion is interposed between the second terminal and the third terminal, and the resistor portion is sandwiched and electrically insulated from the thermally responsive element and the movable plate. The

  Next, a safety device according to a second invention is a safety device configured to close a contact circuit when a thermally responsive element senses a temperature rise around the element and reverses the direction of warping, and is fixed to the first terminal. A movable plate having a movable contact at a position opposite to the contact and connected to the second terminal, a thermally responsive element that opens the contact circuit when in a normal warping state, the thermally responsive element and the movable plate Between the third terminal and the fourth terminal which are electrically insulated from the thermal responsive element and the movable plate and are independent of the first and second terminals. And a resistor.

  In the safety device, the resistor is configured to have flexibility, for example, and when the thermally responsive element is warped in the normal warp direction at a predetermined operating temperature or lower, the thermally responsive element and the movable plate In close contact with each other, and the heat response element, the movable plate, and the resistor are in close contact with each other by the reversal operation from the normal warping direction above the predetermined operating temperature of the heat response body. The target state is opened.

  Subsequently, a safety device according to a third aspect of the present invention is the safety device configured to close the contact circuit when the thermally responsive element senses a temperature rise around the element and reverses the direction of warping, and is connected to the first terminal. A movable plate having a movable contact at the apex that is positioned opposite to the fixed contact and having a substantially U-shape, a second terminal connected to one end of the U-shape of the movable plate, and the movable plate The third terminal connected to the other end of the U-shaped is in contact with the movable plate in a normal warping state at a predetermined operating temperature or lower and in an insulative state, and is electrically insulated at the contact portion. And a thermally responsive element that reverses the normal direction of warping based on the heat generated by the movable plate due to a current greater than or equal to a predetermined value flowing between the second terminal and the third terminal. The

In this safety device, for example, when the thermally responsive element performs a reversing operation from the normal warping direction at a predetermined operating temperature or higher, contact between the thermally responsive element and the movable plate is released. Configured to be.
Furthermore, the safety device of the fourth invention is a safety device configured to close the contact circuit when the thermally responsive element senses the temperature rise around the element and reverses the direction of warping, and is fixed to the first terminal. It has a movable contact at the apex that is opposite to the contact and is formed in a substantially U shape. One end of the U shape is connected to the second terminal, and the other end of the U shape is connected to the third terminal. And a thermoresponsive element that reverses the normal warping direction based on self-heating caused by a current greater than or equal to a predetermined value flowing between the second terminal and the third terminal.

  When the movable plate or the thermally responsive element is U-shaped, the first terminal is connected to the second terminal or the third terminal when the thermally responsive element reverses the normal warping direction. The contact circuit is configured to be configured between the two.

  According to the safety device of the present invention, since it operates with a slight shunt from the power supply circuit, it is possible to detect the overcurrent of the power supply circuit while minimizing the resistance of the device circuit and not to pass a large current directly. In addition, even when handling a large current, it is economical because it is small and does not need to be enlarged.

In addition, since it operates with a shunt current from the power supply circuit, the resistance value and structure of the safety device resistor can be selected according to the resistance of the power supply circuit and the interrupting conditions, thereby setting the detection resistance in a wide range Is possible.
In addition to current, operation at temperature is also possible, so it is also possible to shut off the power supply by detecting abnormal temperatures such as power supply wires, power supply transformers, batteries, or connector parts that are intermediate connection parts. It is usable and convenient.

Further, the overcurrent detection unit can be set between two points of an arbitrary conductor of the power supply circuit. Therefore, the arrangement location is flexible regardless of the power supply side or the ground side, which is convenient.
In addition, the contact configuration of the detector is OFF at room temperature, so there is no need to use a normal operation relay, and there is no relay operation when starting up the power supply / load system. A load system can be constructed.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 (a) is a plan view of the safety device according to the first embodiment, FIG. 1 (b) is a side sectional view thereof, and FIG. 1 (c) is a view showing an internal resistor taken out. . As shown in FIGS. 4A and 4B, the safety device 1 includes a housing 2, a first terminal 3, a second terminal 4, and a third terminal drawn out of the housing 2. Terminal 5 is provided. The first terminal 3 is an uncovered metal plate, and the second terminal 4 and the third terminal 5 are both ends covered with a covering member 6 with metal wires and disposed inside and outside the housing 2. The part is exposed from the covering material 6.

  Inside the housing 2, a fixed contact 7 connected to the first terminal 3 is disposed at the bottom left end of the housing 2. Then, the movable plate 9 having the movable contact 8 at a position facing the fixed contact 7 has a longitudinal end where the movable contact 8 is located as a free end, and an opposite end on the right end side of the housing 2. The unit 11 is fixedly supported and arranged.

  The movable plate 9 has a claw portion 9a formed at the tip of the free end, and a substantially central portion of the bottom surface is formed integrally with the support portion 11 and extends from the support portion 11 to the left side of the housing 2. The base portion is supported from below by a convex portion 12 formed at the distal end of the extending portion. The movable plate 9 is connected to the second terminal 4 via the electrode 13 and the internal wiring 14.

The safety device 1 has a bimetal 15 as a thermally responsive element disposed at one end supported by the support portion 11 and the other end inserted into the folded claw portion 9a of the movable plate 9, and is movable with the bimetal 15. A resistor 16 disposed between the plates 9 is provided.
Although the thermally responsive element used for the structure of the detection part which detects said excessive electric current is not restricted to a bimetal element, in this example, it demonstrates by the example using a bimetal element. A bimetal element is generally a bimetal obtained by bonding two or more metals having different coefficients of thermal expansion to a curved shape by press working, and can set an operation that instantaneously reverses the warping direction at a predetermined temperature.

  Further, when this is applied to a switch operation, a contact is provided in order to surely connect / cut off the current, and it is used in combination with a spring mechanism for bringing the contacts into contact with each other with a constant pressure. Depending on the combination of the bimetal warping direction and this spring mechanism, the configuration of the current detection unit of either the normal temperature ON configuration or the normal temperature OFF configuration can be employed.

  When an ON-type detection unit at room temperature is used, the shut-off unit becomes a relay type, and it is necessary to operate the relay each time a system incorporating this safety device is activated and to connect the power source. While the system is in the operating state, the connection state is maintained by the relay. When an abnormality is detected, the detection unit and the relay are turned off in this order, and the power supply is shut off.

  On the other hand, in the normal temperature OFF type detection unit, a latch is set in the interrupting unit to maintain the connection state. When an abnormality is detected, the detection unit is turned on, current flows in the tripping unit, and the latch is removed. As a result, blocking is realized. Since it operates only when there is an abnormality, it is advantageous in terms of life and reliability of the safety device.

  The resistor 16 is preferably a sheet-like resistor that is thin and flexible. A sheet of stainless steel or nichrome, which is a resistance material, may be used. Depending on the resistance value, nickel or copper alloy having a lower resistance can be used. Such a sheet-like metal material is patterned by pressing or etching, and insulation treatment is performed on both sides with an insulating film or coating, and a movable element with a movable contact attached to a reversing operation (eg, bimetal 15). It is attached so as to be sandwiched between the plate 15 and a lead wire having a required length is attached to each terminal, and is inserted into the housing 2 and sealed.

  The resistor 16 is a resistor having a relatively small resistance value, and when the bimetal 15 is warped together with the movable plate 9 in a normal warping direction below a predetermined operating temperature, as shown in FIG. Is in close contact with both the movable plate 9 and the bimetal 15. Although not shown in particular, when the bimetal 15 performs a reversing operation from the normal warping direction shown in FIG. 5 (b) at a predetermined operating temperature or more, the fixed contact 7 and the movable contact 8 are closed to form a contact circuit. The close contact state between the three members of the bimetal 15, the movable plate 9, and the resistor 16 is released.

  As shown in FIG. 6C, the resistor 16 has a shape in which the letter “J” is placed horizontally, and a portion sandwiched between the bimetal 15 and the movable plate 9 is covered with an insulating sheet 17 from both sides (same as above). In FIG. (B), the upper insulating sheet 17 is removed). On the one hand, the short end of the J-shaped side is connected to the second terminal 4 and the movable plate 9 via the electrode 13, and on the other hand, the long end of the J-shape is directly connected to the third terminal 5. It is connected. A mounting hole 18 is formed adjacent to the electrode 13.

  The resistor 16 generates heat above a predetermined operating temperature of the bimetal 15 when a predetermined current or more flows between the second terminal 4 and the third terminal 5. When the bimetal 15 performs the reversing operation at a predetermined operating temperature or more and the fixed contact 7 and the movable contact 8 are closed, a contact circuit is formed between the first terminal 3 and the second terminal 4.

  For example, in a test assuming that the power supply current is relatively low, the resistance value of the resistor 16 is set to 0.2Ω. When the resistance value of the power supply wire was set to 35 mΩ as an operation check, when the current of the power supply wire 83A flowed, a current of about 10.6 A flowed through the resistor 16 and operated for 1 second.

This is because the voltage drop at 83A is about 2.8V in the 35mΩ power line, the current of 10.6A flows through the 0.2Ω resistor, the power of about 30W is consumed, and the bimetal 15 takes about 1 second. It has worked.
If the wiring resistance between two points in a certain section of the power supply wire, the short-circuit current value to be cut off, and the cut-off time are measured, the resistance value of the detection resistor can be calculated from these relational characteristic diagrams. .

  FIG. 2 (a) is a diagram showing an example of a system in which the safety device 1 as a switch having an OFF configuration at normal temperature is combined with a latch-type shut-off unit in a power supply / load circuit, and FIG. It is a figure which shows an example of the modification of a safety device, and an example of a power supply and load circuit system using the same. In FIGS. 1 (a), (b), components having the same functions as those in FIGS. 1 (a), (b), (c) are shown in FIGS. 1 (a), (b), (c). The same reference numerals are given.

  The power source / load system shown in FIG. 2A includes a power source 19, a load 20, and a power source line 21 (a plus side power source line 21a and a minus side power source line 21b) connecting the power source 19 and the load 20. A tripping unit 22 that cuts off the power supply circuit is disposed on the positive power supply line 21a. The tripping unit 22 includes a normally closed switch 23 disposed at an appropriate intermediate portion of the plus-side power line 21a in which a current flows in the direction of arrow a, a latching relay device 24 that opens the normally closed switch 23, and the like.

  In this power source / load system, the safety device 1 of this example operates as an overcurrent detector. First, as shown in FIG. 6A, the second terminal 4 and the third terminal 5 to which the resistor 16 of the safety device 1 is connected have a predetermined wiring resistance of the positive power supply line 21a. It connects to the line pulled out from both ends 21-1 and 21-2 of b.

  Note that the wiring resistance in this section b has an (internal resistance) resistance value of about several mΩ, whereas the resistance value of the resistor 16 is set to several tens mΩ to several hundreds mΩ. Further, this connection is not limited to the plus power supply line 21a, and may be a section having a predetermined wiring resistance of the minus power supply line 21b.

  With the above connection, a current corresponding to the voltage division according to the ratio between the wiring resistance value of the section b and the resistance value of the resistor 16 is shunted to the resistor 16. However, in the normal current range of the power supply wiring, the resistor The shunt current to 16 is also small, and the heat generation of the resistor 16 inside the safety device 1 is small. As described above, the resistance value of the resistor 16 is set to such a resistance value that only generates a small amount of heat that does not cause the bimetal 15 to perform a reverse operation with a normal shunt current.

  However, when the short circuit 25 occurs in the power supply wiring 21 for some reason, an excessive current flows in the power supply wiring 21. As described above, when an excessive current flows in the power supply wiring 21 as in the case of the short circuit 25, even if the wire resistance of the power supply wiring 21 is very small, it is relatively between the both ends 21-1 and 21-2 of the section b. It shows a large voltage drop.

  For example, if there is a power supply wire having a resistance value of 1 mΩ in the section b, when a short-circuit current of 1000 A flows, a voltage drop of 1 V occurs at both ends 21-1 and 21-2 of the section b. Then, if the resistance value of the resistor 16 connected in parallel with this is set to 0.1Ω, for example, a current of 10 A flows with the potential difference of 1V. Of course, the combined resistance varies somewhat due to the parallel connection, but in any case, the heating element 16 is heated so that the heat generation of the heating element 16 is equal to or higher than the predetermined operating temperature of the bimetal 15 under the above conditions. If the heat generation condition and the reversal operation condition of the bimetal 15 are set, the bimetal 15 can be reversed by the heat generation of the heating element 16 due to the short-circuit current of the power supply wire.

  In this way, the bimetal 15 of the safety device 1 performs a reversing operation in response to the heat generated by the heating element 16, the fixed contact 7 and the movable contact 8 are closed, and the plus connected to the latching relay device 24 of the tripping unit 22 in advance. Contact circuits 26a and 26b are formed on the side wiring, and the power source current is supplied to the latching relay device 24 by the minus side wiring 26c, so that the normally closed switch 23 is tripped and the power source current is cut off.

  In the configuration of the safety device 1, an overcurrent detection unit such as a short circuit, that is, a resistor 16 connected in parallel with a power supply wire, a bimetal 15 that operates by detecting heat generation, a fixed contact 7, and a movable contact 8 are included. Since a large current does not flow in the part including the switch unit, the configuration of the excessive current detection unit can be made very small.

  For this reason, it is possible to mount such that heat is generated by an excessive current such as a short-circuit current, for example, the heat generation of the connector portion of the power cable, power transformer, power battery, and power cable is detected. As a result, not only an excessive current, but also thermal protection of each part such as a power supply and wiring can be performed simultaneously, and it is possible to provide a safety device with little loss and high safety.

  In the safety device 1 that detects an excessive current at the time of the short circuit, the resistor 16, the bimetal 15, and the movable plate 9 as the detection unit are as described above in order to detect the excessive current in a sufficiently short time. In the state of an OFF-type contact portion at normal temperature, the resistor 16 is disposed so as to be in close contact with the bimetal 15 and the movable plate 9 (particularly, the bimetal 15).

  In addition, if the resistor is configured independently, the resistor can be electrically insulated from the switch part. If the resistor is not related to the switch part, there are no restrictions on the mounting as in the switch part, and it can be placed at any position. The current detection position can be selected. That is, the power supply side, the ground side, or the side close to the load may be used.

  Further, the safety device 1 'of the modified example shown in FIG. 2 (b) has a resistor 16 that is electrically independent of the movable plate 9 and is independent of the power line 21 (in the example of FIG. 2 (b), on the plus side). The power supply line 21a) is connected to a line drawn from both ends of the section c having a predetermined wiring resistance. In this case, although not particularly shown, four terminals are drawn out from the housing 2 shown in FIGS. 1 (a) and 1 (b). Even when configured as shown in FIG. 2 (b), the same operation as in FIG. 2 (a) can be obtained.

FIG. 3 (a) is a plan view showing a movable plate / resistor used in the safety device according to the second embodiment, and FIG. 3 (b) is a diagram before being processed into a shape as a resistor. It is a figure which shows the movable plate shown to 1 (a), (b) for reference.
The movable plate / resistor 9 ′ shown in FIG. 3 (a) is cut from the movable plate 9 shown in FIG. 3 (b) to the vicinity of the contact 8 from the terminal side to the center as shown in FIG. 3 (a). The movable plate 9 shown in FIG. 2B is formed as a resistor having a U shape (in FIG. 1A, the U shape is rotated 90 degrees to the right). The U-shaped end portions 9'-1 and 9'-2 are connected to the second terminal 4 and the third terminal 5 with the U-shaped end portions 9'-1 and 9'-2 as terminal portions. Attach the lead wire to 2 by welding.

A movable contact 8 is attached to the apex of the U-shape of the movable plate / resistor 9 '. Further, when the bimetal 15 is placed on the upper side of the movable plate / resistor 9 ', a folding claw portion 9a for lifting the movable plate / resistor 9' is provided at the tip.
In this example, since the movable plate 9 also serves as a resistor and serves as a movable plate / resistor 9 ′, the resistor 16 shown in FIG. 1 (c) is not necessary. In addition, the movable plate / resistor 9 ′ has a potential difference of several volts during the short-circuit current detection operation between the ends of the U-shape, and is shown in FIGS. 1 (a) and 1 (b). It is necessary to insulate from the bimetal 15.

  This insulation can be handled with a heat-resistant insulating sheet or insulating tape. When the resistance value for detecting the short-circuit current is relatively small, for example, 0.1Ω or less, the configuration as shown in FIG. 3 (a) is effective and used as the movable plate / resistor 9 ′. The resistance value can be adjusted depending on the material. As a material, beryllium copper is used for a low resistance material that is a general spring material, and stainless steel is used for a high resistance material. Other titanium copper alloys and copper nickel alloys can also be used.

FIG. 4 (a) is a plan view showing a thermally responsive element / resistor used in the safety device in the third embodiment, and FIG. 4 (b) is a diagram before being processed into a shape as a resistor. It is a figure which shows the bimetal of a flat plate for reference.
The thermally responsive element / resistor 28 'shown in FIG. 4 (a) is substantially the same as that shown in FIGS. 1 (a) and 1 (b) as shown in FIG. As in the case of the movable plate 9, a notch 28 is formed from the terminal side to the vicinity of the left end as shown in FIG. 9 (a), and a U-shape (the U-shape in FIG. (A shape rotated 90 degrees to the right).

  Both ends 15'-1 and 15'-2 of the U-shape are formed as terminal portions longer than in the case of FIG. In order to connect these U-shaped end portions 15′-1 and 15′-2 as the terminal portions to the second terminal 4 and the third terminal 5, both U-shaped end portions 15′-1 and 15 ′. Attach the lead wire to -2.

  In general, many types of protectors using a bimetal are used in which a current flows through the bimetallic thermal element itself. Most of them are reversal-type thermosensitive elements having a warped shape, but the thermoresponsive element / resistor 15 'of this example is slightly displaced in the direction of opening or closing the vicinity of the U-shaped end. Thus, it is possible to set the reversal operation, and it is possible to form a shape that warps around the front end of the cut. By attaching the contact 8 to the U-shaped tip in advance, and using the bimetal 15 itself as a resistor and using it as a thermal actuator / resistor 15 ', it can be used as it is as a switch.

  That is, when the bending direction of the thermoresponsive element / resistor 15 ′ set as described above is set as the warping direction at room temperature, the time when the bending force exceeds the limit that can be suppressed by the warping shape due to temperature rise. Then, a snap action to reverse the direction of warping is performed.

  In addition, the bimetal can change the curvature coefficient and the volume resistivity depending on the combined material, and can also be a low-resistance material by using a tri-layer trimetal using a low-resistance material for the intermediate layer. . When a detection current flows in such a bimetal itself, the bimetal generates Joule heat and is inverted at a predetermined temperature by the heat of the bimetal itself. Since the structure is simple and the resistor itself is a thermal element, the current response is the fastest response and the most sensitive configuration in the present invention.

  Although not particularly illustrated, the detection unit is not limited to the installation location, and for example, if overheating of the power supply wire is a problem, it can be attached so as to contact the power supply wire, For example, if protection is required with a transformer or a battery, it is also possible to attach so as to detect these temperatures. Of course, the same applies not only to the electric wires but also to the connectors and terminal portions of the connecting portions.

  If the shut-off unit is a latch type, it is possible to check the function of the detection unit by passing only the detection current through the resistor with the latch removed in advance. This is also a convenient configuration in terms of points.

(a) is a plan view of the safety device according to the first embodiment, (b) is a side sectional view thereof, and (c) is a view showing an internal resistor taken out. (a) is a diagram showing an example of a system in which a safety device of a switch having an OFF configuration at room temperature is combined with a latch type shut-off unit in a power supply / load circuit, and (b) is a modified example of the configuration of the safety device and using it It is a figure which shows an example of a power supply and load system. (a) is a top view which shows the movable plate and resistor used for the safety device in 2nd Embodiment, (b) is a figure which shows the movable plate before processing into the shape as a resistor for reference It is. (a) is a plane showing a thermoresponsive element / resistor used in the safety device in the third embodiment, and (b) is a bimetal of a flat plate before being processed into a shape as a resistor for reference. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Safety device 2 Housing 3 1st terminal 4 2nd terminal 5 3rd terminal 6 Coating | covering material 7 Fixed contact 8 Movable contact 9 Movable plate 9a Folding nail | claw part 9 'Movable plate and resistor 9'-1, 9' -2 U-shaped both ends 11 Supporting portion 12 Protruding portion 13 Electrode 14 Internal wiring 15 Bimetal 15'-1, 15'-2 Both ends of U-shaped 16 Resistor 17 Insulating sheet 18 Mounting hole 19 Power source 20 Load 21 Power line 21a Positive side power line 21b Negative side power line 21-1, 21-2 End of section b 22 Trip unit 23 Normally closed switch 24 Latching relay device 25 Short circuit 26a, 26b Contact circuit 26c Negative side wiring 27, 28 Notch

Claims (7)

In the safety device configured to close the contact circuit when the thermally responsive element senses the temperature rise around the element and reverses the direction of warping,
A movable plate connected to the second terminal having a movable contact at a position opposite to the fixed contact connected to the first terminal;
A thermally responsive element that opens the contact circuit when in a normal warping state;
A resistor portion sandwiched between the thermally responsive element and the movable plate and electrically insulated from the thermally responsive element and the movable plate, and connected between the second terminal and the third terminal. Body,
A safety device comprising: In the safety device configured to close the contact circuit when the thermally responsive element senses the temperature rise around the element and reverses the direction of warping,
A movable plate connected to the second terminal having a movable contact at a position opposite to the fixed contact connected to the first terminal;
A thermally responsive element that opens the contact circuit when in a normal warping state;
A resistor portion is sandwiched between the thermally responsive element and the movable plate so as to be electrically insulated from the thermally responsive element and the movable plate, and a third terminal and a second terminal independent of the first and second terminals. A resistor connected between the four terminals;
A safety device comprising: The resistor is configured to have flexibility, and is in close contact with the thermally responsive element and the movable plate when the thermally responsive element is warped in the normal warping direction below a predetermined operating temperature. And
The intimate state between the three members of the thermally responsive element, the movable plate, and the resistor is released by the reversal operation from the normal warping direction at a predetermined operating temperature of the thermally responsive body.
The safety device according to claim 1 or 2, characterized in that. In the safety device configured to close the contact circuit when the thermally responsive element senses the temperature rise around the element and reverses the direction of warping,
A movable plate formed in a substantially U shape having a movable contact at the apex portion which is a position facing the fixed contact connected to the first terminal;
A second terminal connected to one end of the U-shape of the movable plate;
A third terminal connected to the other end of the U-shape of the movable plate;
It is disposed in contact with the movable plate in a state of normal warping below a predetermined operating temperature in an intimate contact state and electrically insulated at the contact portion, and is more than a predetermined amount between the second terminal and the third terminal. A thermally responsive element that reverses the normal warping direction based on the heat generated by the movable plate due to the flow of the current;
A safety device comprising:   When the thermally responsive element performs a reversing operation from the normal warping direction at a predetermined operating temperature or higher, contact between the thermally responsive element and the movable plate is released. The safety device according to claim 4. In the safety device configured to close the contact circuit when the thermally responsive element senses the temperature rise around the element and reverses the direction of warping,
It has a movable contact at the apex that is positioned opposite to the fixed contact connected to the first terminal, is formed in a substantially U shape, and one end of the U shape is connected to the second terminal. A heat-responsive element having an end connected to a third terminal and reversing the normal warping direction based on self-heating caused by a current greater than or equal to a predetermined amount flowing between the second terminal and the third terminal; Safety device characterized by that. 5. The first terminal forms a contact circuit with the second terminal or the third terminal when the thermally responsive element reverses the normal warping direction. Or the safety device of 6.

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