JP2015015150A - Breaker and safety circuit including the same and secondary battery circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To combine compaction and enhancement of the yield, in a breaker used as a protective device for a secondary battery, or the like.SOLUTION: A breaker 1 includes a fixed piece 2 having a fixed contact 21, a movable piece 4 having a movable contact 3, a thermally-actuated element 5 for actuating the movable piece 4 so that the movable contact 3 is separated from the fixed contact 21 by deforming as the temperature changes, and a case 7 for housing the fixed piece 2, movable piece 4 and thermally-actuated element 5. The thermally-actuated element 5 has a first protrusion 53 protruding to the side opposite from the movable piece 4. When the thermally-actuated element 5 is in the inverted shape, the first protrusion 53 abuts against the thermally-actuated element 5, and supports the thermally-actuated element 5. Consequently, a stress generated in the thermally-actuated element 5 is dispersed, and the thermally-actuated element 5 is reset forward at a desired temperature, without setting a smaller radius of curvature while using a thin thermally-actuated element 5.

Description

  The present invention relates to a small breaker built in a secondary battery pack or the like of an electric device.

  Conventionally, a breaker is used as a protection device (safety circuit) for secondary batteries and motors of various electric devices. When the temperature of the secondary battery during charging / discharging rises excessively, or when an abnormality occurs such as when an overcurrent flows through a motor or the like equipped in a device such as an automobile or home appliance, Cut off current to protect secondary batteries and motors. Breakers used as such protective devices operate accurately following temperature changes (having good temperature characteristics) and have stable resistance when energized to ensure the safety of the equipment. It is required to be.

  In addition, when the breaker is used as a protection device for a secondary battery or the like installed in an electric device such as a thin-type multifunctional mobile phone called a notebook personal computer, a tablet-type portable information terminal device, or a smartphone, the above-described case is used. In addition to ensuring safety, miniaturization is required. In particular, in recent portable information terminal devices, users have a strong desire for miniaturization (thinning), and devices newly released by each company are designed to be small in order to ensure superiority in design. The tendency to be remarkable is remarkable. Against this background, breakers that are mounted together with secondary batteries as one component of portable information terminal devices are also strongly required to be further miniaturized.

  The breaker is provided with a thermally responsive element that operates according to a temperature change and conducts or cuts off a current. Patent Document 1 discloses a breaker to which a bimetal is applied as a thermally responsive element. Bimetal is an element that is formed by laminating two types of plate-like metal materials having different coefficients of thermal expansion, and controls the conduction state of the contact by changing the shape in accordance with a temperature change. The breaker shown in the same document is a case in which parts such as a fixed piece, a movable piece, a thermally responsive element, and a PTC thermistor are housed in a case, and terminals of the fixed piece and the movable piece are connected to an electric circuit of an electric device. Used. In the breaker disclosed in Patent Document 1, the fixed piece is incorporated into the case body by insert molding (see paragraph (0031) of the same document).

  In the energized state shown in FIG. 3 of the same document, the thermoresponsive element takes a normal rotation shape. When the temperature of the thermally responsive element rises due to overcharge or the like, the snap action causes the thermally responsive element to change to an inverted shape as shown in FIG. 4 of the same document, pushing up the vicinity of the tip of the movable piece. As a result, the fixed contact provided on the fixed piece and the movable contact provided on the movable piece are separated from each other, and the breaker is cut off.

  Thereafter, when the overcharged state is eliminated, the temperature of the thermally responsive element decreases, the thermally responsive element returns to the normal rotation shape, and the breaker returns to the energized state. The reverse operation temperature at which the breaker changes from the energized state to the cut-off state and the normal rotation return temperature at which the breaker changes from the cut-off state to the energized state depend on the elastic force generated by the movable piece and the elastic force generated by the thermally responsive element. The elastic force of the movable piece in the interrupted state is larger than the elastic force of the movable piece in the energized state. Therefore, in general, the reversal operation temperature in the finished product of the breaker is substantially equal to the reversal operation temperature in the single unit of the thermally responsive element, whereas the normal return temperature in the finished product of the breaker is the elastic force generated by the movable piece. It is affected and becomes higher than the normal rotation recovery temperature of the single element of the thermally responsive element (see Table 1 described later).

WO2011 / 105175 gazette

  In order to reduce the size of the breaker, it is effective to reduce the plate thickness of the fixed piece, the movable piece, and the thermally responsive element. However, when the thermally responsive element is formed thin, the holding force for holding the vicinity of the tip of the movable piece in a non-conductive state, that is, the elastic force generated by the thermally responsive element is reduced. Accordingly, when the normal rotation recovery temperature of the single heat-responsive element is set to be equal to that of the heat-responsive element having a large thickness (see Comparative Example 1), as shown in Comparative Example 2, the heat having a small thickness is used. The responding element yields to the elastic force of the movable piece at a higher temperature and returns to the normal rotation shape. In particular, in the non-conducting state, since the thermal actuator and the PTC thermistor are in contact with each other in a spot-like narrow area, stress is likely to concentrate on the contact area, and the thin thermal actuator can be easily corrected. Strong tendency to return to rolling shape.

  Therefore, in order to keep the normal rotation return temperature in the finished product of the breaker low while using the thin thermal response element, as shown in Comparative Example 3, the normal rotation return of the single thermal response element is performed. The temperature must be set lower than that of Comparative Example 2, and for that purpose, the radius of curvature of the bending process of the thermally responsive element needs to be set small.

  However, the thermoresponsive element with a small radius of curvature has a large difference between the reversal operating temperature and the normal rotation recovery temperature (high hysteresis), so the normal rotation recovery temperature is likely to vary, and the miniaturization was sought in particular. In a breaker, it is difficult to manufacture a thermally responsive element having a small radius of curvature with a stable quality, which is a cause of a decrease in yield.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a breaker capable of achieving both reduction in size and improvement in yield.

  In order to achieve the above object, a breaker of the present invention includes a fixed piece having a fixed contact, a movable contact, a movable piece that presses the movable contact against the fixed contact, and a temperature change. In a breaker including a thermally responsive element that operates the movable piece so that the movable contact is separated from the fixed contact by being deformed, the thermal responsive element protrudes on a side opposite to the movable piece. A first protrusion is formed.

  In the present invention, it is preferable that the first protrusion is formed around the center of the thermally responsive element.

  In this invention, it is preferable that the said 1st protrusion part is formed cyclically | annularly.

  In this invention, it is preferable that a plurality of the first protrusions are formed in a scattered manner.

  Further, the flaker of the present invention has a fixed piece having a fixed contact, a movable contact, a movable piece that presses the movable contact against the fixed contact, and the movable piece by being deformed in accordance with a temperature change. A thermal responsive element that operates the movable piece such that the contact is separated from the fixed contact; and is interposed between the thermal responsive element and the fixed piece, and the movable contact is separated from the fixed contact. In addition, in the breaker provided with a positive temperature coefficient thermistor for conducting the movable piece and the fixed piece through the thermal response element, the positive temperature coefficient thermistor has a second protrusion protruding toward the thermal response element. A portion is formed.

  In the present invention, it is preferable that the second protrusion is formed around the center of the thermally responsive element.

  In this invention, it is preferable that the said 2nd protrusion part is formed cyclically | annularly.

  In this invention, it is preferable that a plurality of the second protrusions are formed in a scattered manner.

  A safety circuit for an electric device according to the present invention includes the breaker.

  The secondary battery pack according to the present invention includes the breaker.

  According to the breaker 1 of the present invention, since the first projecting portion projecting to the side opposite to the movable piece is formed on the thermally responsive element, when the movable contact is separated from the fixed contact, that is, the thermally responsive When the element is in an inverted shape, the first protrusion comes into contact with a component on the side opposite to the movable piece. Therefore, by providing the first protrusion away from the location where stress is likely to concentrate in the thermal actuator, the stress generated in the thermal actuator can be easily dispersed, and the normal rotation return temperature of the thermal actuator in the finished product of the breaker can be increased. It can be kept low. Therefore, it is possible to return the thermoresponsive element to a normal rotation at a desired temperature in the finished product breaker without using a small radius of curvature while using a thin thermoresponsive element. This makes it possible to achieve both a reduction in the size of the breaker and an improvement in yield.

  According to the configuration in which the first protrusion is formed around the center of the thermal actuator, the stress generated in the thermal actuator can be dispersed at the center where the stress tends to concentrate. The normal rotation return temperature can be easily maintained low.

  According to the configuration in which the thermally responsive element at the time of thermal deformation is supported by the first projecting portion formed continuously in an annular shape, the stress at the center of the thermally responsive element can be more effectively dispersed.

  According to the configuration in which the thermally responsive element at the time of thermal deformation is supported by the plurality of first projecting portions formed in a scattered manner, the stress at the center of the thermally responsive element can be more effectively reduced as in the above configuration. Can be dispersed.

  In addition, according to the breaker of the present invention, since the second projecting portion projecting toward the thermally responsive element is formed on the positive temperature coefficient thermistor, when the movable contact is separated from the fixed contact, that is, the thermally responsive When the element is in an inverted shape, the second protrusion comes into contact with the thermally responsive element. Therefore, by providing the second protrusion away from the location where stress tends to concentrate in the thermal actuator, the stress generated in the thermal actuator can be easily dispersed, and the normal rotation return temperature of the thermal actuator in the finished breaker product can be increased. It can be kept low. Therefore, it is possible to return the thermoresponsive element to a normal rotation at a desired temperature in the finished product breaker without using a small radius of curvature while using a thin thermoresponsive element. This makes it possible to achieve both a reduction in the size of the breaker and an improvement in yield.

  According to the configuration in which the second protrusion is formed around the center of the thermal response element, the stress generated in the thermal response element can be dispersed at the center where the stress tends to concentrate. The normal rotation return temperature can be easily maintained low.

  According to the configuration in which the thermally responsive element at the time of thermal deformation is supported by the second protrusion formed continuously in an annular shape, the stress at the center of the thermally responsive element can be more effectively distributed.

  According to the configuration in which the thermally responsive element at the time of thermal deformation is supported by the plurality of second projecting portions that are formed in a scattered manner, the stress at the center of the thermally responsive element is more effectively reduced as in the above configuration. Can be dispersed.

  Moreover, according to the safety circuit or the secondary battery pack provided with the breaker of the present invention, it is possible to manufacture a safety circuit or a secondary battery pack that achieves both a reduction in the size of the breaker and an improvement in yield.

The assembly perspective view which shows the structure of the breaker by one Embodiment of this invention. Sectional drawing which shows operation | movement of the breaker in a normal charge state or discharge state. Sectional drawing which shows operation | movement of a breaker in the time of an overcharge state or abnormality. (A) is a perspective view which shows the normal rotation shape of the thermoresponsive element applied to the breaker, (b) is a perspective view which shows the inversion shape of the thermoresponsive element. (A) is sectional drawing which shows the normal rotation shape of the center vicinity of the thermoresponsive element, (b) is sectional drawing which shows the inversion shape of the thermodynamic element vicinity of the center. Sectional drawing which shows the inversion operation | movement of the thermoresponsive element in a breaker. (A), (b), (c) is a top view which shows the modification of the thermal responsive element. (A) is a perspective view which shows the structure of the PTC thermistor applied to the breaker, (b) is the cross-sectional view. (B), (c), (d) is a top view which shows the modification of the PTC thermistor. The top view which shows the structure of the secondary battery pack provided with the breaker of this invention. The circuit diagram of the safety circuit provided with the breaker of this invention.

  A breaker according to an embodiment of the present invention will be described with reference to the drawings. 1 to 3 show the configuration of the breaker. The breaker 1 includes a fixed piece 2 having a fixed contact 21, a movable piece 4 having a movable contact 3 at the tip, a thermally responsive element 5 that deforms with a change in temperature, a PTC (Positive Temperature Coefficient) thermistor 6, , A fixed piece 2, a movable piece 4, a thermally responsive element 5, and a case 7 for housing a PTC thermistor 6. The case 7 includes a resin base (first case) 71, a cover member (second case) 72 attached to the upper surface of the resin base 71, a cover piece 8, and the like.

  The fixing piece 2 is formed by pressing a metal plate mainly composed of phosphor bronze or the like (other metal plate such as copper-titanium alloy, white or brass) and embedded in the resin base 71 by insert molding. It is. A terminal 22 electrically connected to an external circuit is formed at one end of the fixed piece 2, and a support portion 23 that supports the PTC thermistor 6 is formed at the other end side. The PTC thermistor 6 is placed on the projections (dowels) 24a formed at three places on the support portion 23 of the fixed piece 2, and is supported by the projections 24a. The fixed contact 21 is formed at a position facing the movable contact 3 by cladding, plating, coating, or the like of a conductive material such as silver, nickel, nickel-silver alloy, copper-silver alloy, gold-silver alloy. , The resin base 71 is exposed from a part of the opening 73b formed above. The terminal 22 protrudes outward from one end of the resin base 71.

  In the present application, in the fixed piece 2, the surface on which the fixed contact 21 is formed (that is, the upper surface in FIG. 1) is the front surface, and the opposite surface is the back surface. As described. The same applies to other components, for example, the thermally responsive element 5.

  The fixed piece 2 is exposed at the terminal 22, the fixed contact 21, and the support portion 23 (the back surface corresponds to the exposed portion 23 d in the drawing), and between the terminal 22 and the fixed contact 21 and between the fixed contact 21 and the support portion 23. It is embedded in the resin base 71 between. The surface of the support portion 23 of the fixed piece 2 is exposed to the accommodation space inside the case 7 and is in electrical contact with the PTC thermistor 6 through the protrusion 24a.

  The movable piece 4 is formed in an arm shape symmetrical to the center line in the longitudinal direction by pressing a plate-like metal material. As a material of the movable piece 4, a material mainly composed of phosphor bronze or the like equivalent to the fixed piece 2 is preferable. In addition, a conductive elastic material such as copper-titanium alloy, white or brass may be used. A terminal 41 electrically connected to an external circuit is formed at one end in the longitudinal direction of the movable piece 4 and is exposed to the outside from the resin base 71. A movable contact 3 is formed at the other end of the movable piece 4 (corresponding to the tip of the arm-shaped movable piece 4). The movable contact 3 is formed of the same material as that of the fixed contact 21 and is joined to the tip of the movable piece 4 by a technique such as clad or crimping in addition to welding. The movable piece 4 has a contact portion 42 (corresponding to a base end of the arm-like movable piece 4 and a portion embedded in the case 7) and an elastic portion 43 between the movable contact 3 and the terminal 41. . The contact portion 42 has a protrusion 42 a that contacts the resin base 71 and the cover member 72 between the terminal 41 and the elastic portion 43 and protrudes in a wing shape in the short direction of the movable piece 4. The elastic part 43 extends from the contact part 42 to the movable contact 3 side. The movable piece 4 is fixed by being sandwiched by the resin base 71 and the cover member 72 at the abutting portion 42 from the front and back sides, and the elastic portion 43 is elastically deformed, whereby the movable contact 3 formed at the tip thereof is a fixed contact. The fixed piece 2 and the movable piece 4 can be energized by being pressed and brought into contact with the side 21.

  The resin base 71 and the cover member 72 are respectively formed with an abutting portion 74 and an abutting portion 79 that abut against the abutting portion 42 of the movable piece 4 and hold the abutting portion 42 in a fixed state. In the present embodiment, a contact portion 74 is formed in a region extending from the outer edge of the housing portion 73 of the resin base 71 to the outer wall of the resin base 71. The contact portion 74 constitutes a part of the bottom wall (inner bottom surface) of the case 7 in FIG. In the cover member 72, a contact portion 79 is formed in a region facing the contact portion 74 with the movable piece 4 interposed therebetween. The contact portion 79 constitutes a part of the top wall (inner top surface) of the case 7 in FIG. The contact portion 42 contacts the contact portion 74 of the resin base 71 on the back surface, and contacts the contact portion 79 of the cover member 72 on the front surface. The movable piece 4 is sandwiched from the front and back surfaces of the contact portion 42 by the contact portion 74 and the contact portion 79 and fixed to the case 7. In this embodiment, since the contact part 42 has the protrusion part 42a which protrudes in the shape of a wing in the transversal direction of the movable piece 4, the contact part 74 and the contact part of the case 7 have a wide and large area. The movable piece 4 is firmly fixed to the case 7 by being sandwiched by 79.

  The movable piece 4 is curved or bent at the elastic portion 43 by pressing. The degree of bending or bending is not particularly limited as long as the thermally responsive element 5 can be accommodated, and may be set as appropriate in consideration of the elastic force at the reversal operation temperature and the normal rotation return temperature, the contact pressing force, and the like. In addition, a pair of protrusions (contact portions) 44 a and 44 b are formed on the lower surface of the elastic portion 43 so as to face the heat-responsive element 5. The protrusions 44a and 44b and the thermally responsive element 5 come into contact with each other, and the deformation of the thermally responsive element 5 is transmitted to the elastic portion 43 via the protrusions 44a and 44b (see FIGS. 1, 2 and 3).

  Further, the movable piece 4 has a through hole 45 that penetrates in the thickness direction of the movable piece 4 and through which the protrusion 74a of the resin base 71 is inserted, a step bent portion 46 formed in a crank shape, and a step bent portion 46. Part of the movable piece 4 is cut off in the short direction perpendicular to the longitudinal direction of the movable piece 4 and the formed slope 47, the pair of engaging portions 48 engaged with the positioning portion 75 of the resin base 71. A constricted portion 49 is formed. The through hole 45, the step bent part 46, the slope 47, the engaging part 48, and the constricted part 49 are provided on the opposite side of the movable contact 3 with the elastic part 43 interposed therebetween, that is, on the terminal 41 side with respect to the elastic part 43. ing. The through hole 45 is provided on the center line in the longitudinal direction of the movable piece 4. The slope 47 is formed continuously along the short direction of the movable piece 4. The engaging portions 48 are provided at two locations along the short direction of the movable piece 4.

  The through hole 45 is formed in the contact portion 42 of the movable piece 4. The contact portion 42 is formed wider than the elastic portion 43 in the short direction of the movable piece 4. Thereby, the cross-sectional area perpendicular to the longitudinal direction of the movable piece 4 in the contact portion 42 becomes a portion larger than the cross-sectional area in the elastic portion 43. Further, the through hole 45 is formed in an oval shape that is long in the lateral direction of the movable piece 4 in plan view (as viewed in the thickness direction of the movable piece 4).

  The engaging portion 48 is formed at the end edge of the constricted portion 49 on the terminal 41 side. The constricted portion 49 is disposed between the contact portion 42 and the terminal 41 on the side opposite to the elastic portion 43 with the contact portion 42 interposed therebetween. The width dimension of the constricted portion 49 (the length dimension in the short direction of the movable piece 4, the same applies hereinafter) is preferably set equal to or less than the width dimension of the elastic portion 43, but at least the contact portion 42. And it should just be set smaller than the width dimension of the terminal 41. The constricted part 49 in this embodiment has a function as the second elastic part in the above-mentioned Patent Document 1, and absorbs an external force and an impact applied to the terminal 41 and appropriately maintains the position of the movable contact 3. .

  The thermally responsive element 5 has an initial shape curved in an arc shape and is made of a composite material such as bimetal or trimetal. When the reversal operation temperature is reached due to overheating, the curved shape reversely warps with snap motion, and is restored when it falls below the normal rotation return temperature due to cooling. The initial shape of the thermoresponsive element 5 can be formed by pressing. As long as the elastic part 43 of the movable piece 4 is pushed up by the reversing operation of the thermal reaction element 5 at the desired temperature and is restored to the original state by the elastic force of the elastic part 43, the material and shape of the thermal reaction element 5 are not particularly limited. Although not limited, a rectangle is desirable from the viewpoint of productivity and efficiency of reverse warp operation, and a rectangle close to a square is desirable in order to efficiently push up the elastic portion 43 while being small. Examples of the material of the thermally responsive element 5 include, for example, white, brass, and stainless steel including copper-nickel-manganese alloy or nickel-chromium-iron alloy on the high expansion side and iron-nickel alloy on the low expansion side. A laminate of two types of materials having different coefficients of thermal expansion made of various alloys such as steel is used in combination according to the required conditions.

  When the energization of the fixed piece 2 and the movable piece 4 is interrupted by the reverse warping operation of the thermal response element 5, the current flowing through the PTC thermistor 6 increases. As long as the PTC thermistor 6 is a positive characteristic thermistor that limits the current by increasing the resistance value as the temperature rises, the PTC thermistor 6 can be of various types as required, such as an inversion operation current, an inversion operation voltage, an inversion operation temperature, and a normal rotation return temperature The material and shape are not particularly limited as long as these properties are not impaired. In the present embodiment, a ceramic sintered body containing barium titanate, strontium titanate or calcium titanate is used. In addition to the ceramic sintered body, a so-called polymer PTC in which conductive particles such as carbon are contained in a polymer may be used.

  The resin base 71 and the cover member 72 constituting the case 7 are thermoplastic such as flame retardant polyamide (PA), heat-resistant polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT), etc. Molded with resin. A material other than the resin may be applied as long as characteristics equal to or higher than those of the above-described resin can be obtained. The resin base 71 is formed with a housing portion 73 for housing the thermally responsive element 5, the PTC thermistor 6, and the like, and openings 73 a and 73 b for housing the movable piece 4. Note that the edges of the movable piece 4, the thermally responsive element 5, and the PTC thermistor 6 incorporated in the resin base 71 are in contact with each other by a frame formed inside the storage portion 73. Will be guided at the time.

  The resin base 71 has a projection 74a inserted into the through hole 45 of the movable piece 4, a pair of positioning portions 75 for positioning the movable piece 4, and a terminal 41 for exposing the movable piece 4 to the outside. A window 76 is provided. The protrusion 74 a is formed in a shape corresponding to the through hole 45 and reinforces the resin base 71. The height of the projection 74a, that is, the projection amount is set to be larger than the thickness of the movable piece 4, and a concave portion corresponding to the top of the projection 74a is provided on the back surface of the cover member 72 as necessary. The positioning portion 75 is provided in a shape corresponding to the constricted portion 49 of the movable piece 4. That is, the positioning portion 75 is interposed in a portion cut out in the vicinity of the constricted portion 49, reinforces the resin base 71, and is welded to the contact portion 79 of the cover member 72 to increase the rigidity and strength of the case 7. .

  A cover piece 8 is embedded in the cover member 72 by insert molding. The cover piece 8 is formed by pressing a metal plate mainly composed of the above-described phosphor bronze or the like or a metal plate such as stainless steel. As shown in FIGS. 2 and 3, the cover piece 8 abuts on the upper surface of the movable piece 4 as appropriate, restricts the movement of the movable piece 4, and the rigidity and strength of the case 7 as a casing as a result of the cover member 72. Contributes to the downsizing of the breaker 1 The cover piece 8 is formed with protrusions 81a and 81b that protrude toward the movable piece 4 side. The elastic part 43 is pressed in the direction of the thermally responsive element 5 by the projection 81b, and the contact pressure between the fixed contact 21 and the movable contact 3 at the time of energization is optimized.

  As shown in FIG. 1, the cover member 72 is disposed on the upper surface of the resin base 71 so as to close the opening 73 a of the resin base 71 that houses the fixed piece 2, the movable piece 4, the thermally responsive element 5, the PTC thermistor 6, and the like. It is attached to. The resin base 71 and the cover member 72 are joined by, for example, ultrasonic welding.

  FIG. 2 shows the operation of the breaker 1 in a normal charge or discharge state. In a normal charge or discharge state, the thermally responsive element 5 maintains an initial shape (a forward rotation shape before reverse warping), the fixed contact 21 and the movable contact 3 are in contact with each other, the elastic portion 43 of the movable piece 4, etc. The terminals 22 and 41 of the breaker 1 are electrically connected. The elastic part 43 of the movable piece 4 and the thermal responsive element 5 are in contact, and the movable piece 4, the thermal responsive element 5, the PTC thermistor 6 and the fixed piece 2 are electrically connected as a circuit. However, since the resistance of the PTC thermistor 6 is overwhelmingly larger than the resistance of the movable piece 4, the current flowing through the PTC thermistor 6 is substantially larger than the amount flowing through the fixed contact 21 and the movable contact 3. It can be ignored.

  FIG. 3 shows the operation of the breaker 1 in an overcharged state or an abnormality. If the PTC thermistor 6 is overheated due to overcharging or abnormalities, the thermal response element 5 that has reached the reversal operating temperature is warped in reverse, and the elastic portion 43 of the movable piece 4 is pushed up, so that the fixed contact 21 and the movable contact 3 separates. At this time, the current flowing between the fixed contact 21 and the movable contact 3 is interrupted, and a slight leakage current flows through the thermal actuator 5 and the PTC thermistor 6. Since the PTC thermistor 6 continues to generate heat as long as such a leakage current flows, the resistance value is drastically increased while maintaining the thermally actuated element 5 in the reverse warped state, so that the current is a path between the fixed contact 21 and the movable contact 3. There is only the above-described slight leakage current (which constitutes a self-holding circuit). This leakage current can be used for other functions of the safety device.

  When the overcharge state is canceled or the abnormal state is resolved, the heat generation of the PTC thermistor 6 is also stopped, and when the temperature returns to the normal rotation return temperature, the thermally responsive element 5 is restored to the original initial shape. Then, the movable contact 3 and the fixed contact 21 come into contact again by the elastic force of the elastic portion 43 of the movable piece 4, the circuit is released from the interruption state, and returns to the conduction state shown in FIG.

  FIG. 4 shows the configuration of the thermally responsive element 5. In FIG. 4, (a) is the shape at the time of forward rotation (forward rotation shape), which is the initial shape of the thermal response element 5, and (b) is the shape at the time of inversion of the thermal response element 5 (inversion shape). is there. FIG. 5 shows a cross section near the center of the thermally responsive element 5. As in FIG. 4, in FIG. 5, (a) shows the shape when the thermal response element 5 is rotated forward, and (b) shows the shape when the thermal response element 5 is inverted.

  The thermally responsive element 5 is formed by laminating a low expansion coefficient metal layer 51 and a high expansion coefficient metal layer 52. The low expansion coefficient metal layer 51 is provided on the front surface side adjacent to the movable piece 4, and the high expansion coefficient metal layer 52 is provided on the back surface side adjacent to the PTC thermistor 6. The thermally responsive element 5 has an initial shape that is curved in an arc shape so that the central portion protrudes toward the movable piece 4. That is, the low expansion coefficient metal layer 51 and the high expansion coefficient metal layer 51 are positioned so that the low expansion coefficient metal layer 51 is located outside the arc in the radial direction and the high expansion coefficient metal layer 52 is located inside the arc in the radial direction. 52 are laminated.

  When the temperature of the thermally responsive element 5 rises, the high expansion coefficient metal layer 52 expands more than the low expansion coefficient metal layer 51 due to heat, and when the reversal operation temperature is exceeded, FIG. 4B and FIG. Deform to the inverted shape shown. Thereafter, when the temperature of the thermally responsive element 5 decreases, the high expansion coefficient metal layer 52 contracts more than the low expansion coefficient metal layer 51, and when the temperature is lower than the normal rotation recovery temperature, the results are as shown in FIGS. 4 (a) and 5 (a). It returns to the normal rotation shape shown.

  The thermally responsive element 5 has a first projecting portion 53 that projects to the PTC thermistor 6 side, that is, the side opposite to the movable piece 4. In other words, the thermally responsive element 5 protrudes to the back side where the high expansion coefficient metal layer 52 is provided.

  The first protrusion 53 is formed around the center 54 of the thermally responsive element 5. The center 54 of the thermally responsive element 5 is a region excluding the first protrusion 53 when the thermally responsive element 5 is deformed into an inverted shape due to thermal expansion, and is a region located closest to the PTC thermistor 6 side. Say.

  Usually, the center 54 is the center of the area of the thermally responsive element 5 in plan view. For example, when the thermally responsive element 5 is formed in a substantially rectangular shape in plan view, the intersection of the diagonal lines is the center 54 of the thermally responsive element 5. In addition, when the thermally responsive element 5 is formed in a circular shape in plan view, the center of the circle is the center 54 of the thermally responsive element 5.

  The center 54 is a region where the curvature of the thermal response element 5 takes an extreme point when the inverted shape is taken. Assuming that the first projecting portion 53 is not formed on the thermally responsive element 5, the thermally responsive element 5 contacts the PTC thermistor 6 in a very narrow spot-like region including the center 54 during thermal deformation. In this case, since stress concentrates in the region, the thermal responsive element 5 tends to easily return to the normal rotation shape even in a high temperature region.

  In the present embodiment, the first projecting portion 53 is provided on the thermally responsive element 5 in order to alleviate the stress concentration. The 1st protrusion part 53 is formed continuously in cyclic | annular form. The center of the first protrusion 53 formed in an annular shape substantially coincides with the center 54 of the thermally responsive element 5. In the present embodiment, the first projecting portion 53 is continuously formed once, but may be partially interrupted. Moreover, the some 1st protrusion part 53 may be formed concentrically. In this case, the protrusion amount of the first protrusion 53 that is further away from the center 54 of the thermally responsive element 5 is set to be large.

  In FIG. 6, the reversing operation of the thermally responsive element 5 in the breaker 1 is shown enlarged. As already described, when the temperature of the thermally responsive element 5 rises and exceeds the reversal operation temperature, the internal stress of the high expansion coefficient metal layer 52 becomes larger than the internal stress of the low expansion coefficient metal layer 51, and the snap action is performed. Along with this, the thermally responsive element 5 is deformed into an inverted shape. At this time, the first protrusion 53 abuts on the PTC thermistor 6 and supports the main body portion of the thermally responsive element 5. Thereby, the center 54 of the thermally responsive element 5 is separated from the PTC thermistor 6 in a floating state. Therefore, the center 54 of the thermal response element 5 is not subjected to stress due to the contact between the thermal response element 5 and the PTC thermistor 6, and local deformation at the center 54 of the thermal response element 5 is avoided.

  On the other hand, since the thermally responsive element 5 is in contact with the PTC thermistor 6 at the first protrusion 53, the stress associated with the contact with the PTC thermistor 6 is applied to the first protrusion 53. However, the stress applied to the first protrusion 53 is dispersed by disposing the first protrusion 53 at a location away from the center 54 of the thermally responsive element 5. Furthermore, in the present embodiment, since the first protrusion 53 is formed in an annularly continuous region, the contact area between the first protrusion 53 and the PTC thermistor 6 increases, and the stress is dispersed. The effect is obtained more remarkably.

  The amount of protrusion of the first protrusion 53 may be set such that the center 54 slightly contacts the PTC thermistor 6 when the thermally responsive element 5 is deformed into an inverted shape. This is because even in this case, a part of the stress applied to the thermally responsive element 5 can be borne by the first protrusion 53 and the stress applied to the center 54 of the thermally responsive element 5 can be reduced.

  As described above, according to the breaker 1 of the present embodiment, since the first projecting portion 53 that projects to the side opposite to the movable piece 4 is formed on the thermally responsive element 5, the movable contact 3 is the fixed contact 21. When the thermal response element 5 is in the inverted shape, that is, when the thermal response element 5 is in the inverted shape, the first protrusion 53 contacts the PTC thermistor 6 disposed on the side opposite to the movable piece 4. Therefore, by providing the first projecting portion 53 away from the center 54 where stress is likely to concentrate in the thermal actuator 5, the stress generated in the thermal actuator 5 can be easily dispersed, and the normal rotation return temperature in the finished product of the breaker 1. Can be kept low. Therefore, while using the thin thermal actuator 5, it is possible to return the thermal actuator 5 to normal rotation at a desired temperature in the finished breaker 1 without setting the radius of curvature small. Thereby, it becomes possible to achieve both reduction in size of the breaker 1 and improvement in yield.

  In addition, in order to aim at the yield improvement of the breaker 1 mentioned above, it is realizable also by using the thermal responsive element 5 with a big curvature coefficient. The curvature coefficient of the thermally responsive element 5 is adjusted by appropriately changing the ratio of the material and thickness of the low expansion coefficient metal layer 51 and the high expansion coefficient metal layer 52 of the thermal response element 5. In general, the holding force for holding the vicinity of the tip of the movable piece 4 in a non-conductive state by the thermally responsive element 5 is proportional to the curvature coefficient, and when the thermally responsive element 5 is made of the same material, the dimensions of the thermally responsive element 5 are as follows. As the value becomes smaller, the holding force tends to become smaller. Therefore, when miniaturizing the thermally responsive element 5, choices of the material are limited, and it may be difficult to realize a large holding force. However, according to the breaker 1 of the present embodiment, the yield of the breaker 1 can be improved without using the thermal actuator 5 having a particularly large curvature coefficient. Therefore, the low expansion coefficient metal layer 51 of the thermal actuator 5 can be achieved. And the freedom degree of selection of the material etc. which comprise the high expansion coefficient metal layer 52 is raised.

  According to the breaker 1, since the first protrusion 53 is formed around the center 54 of the thermally responsive element 5, the stress generated in the thermally responsive element 5 can be effectively dispersed at the center 54 where stress tends to concentrate. . Thereby, the normal rotation return temperature in the finished product of the breaker 1 can be easily maintained low.

  According to the breaker 1, since the thermally responsive element 5 at the time of thermal deformation is supported by the first projecting portion 53 formed continuously in an annular shape, the stress at the center 54 of the thermally responsive element 5 is more effectively reduced. Can be dispersed.

(Modification 1)
FIG. 7 shows thermal responsive elements 5A, 5B and 5C which are modifications of the thermally responsive element 5. In the thermally responsive element 5A shown in FIG. 7A, three dot-like first protrusions 53a are formed, and in the thermally responsive element 5B shown in FIG. One projecting portion 53b is formed in a dotted manner. The first protrusions 53a and 53b are formed around the center 54 of the thermally responsive elements 5A and 5B. More specifically, the first protrusions 53a and 53b are arranged at equal intervals at a location approximately equidistant from the center 54 of the thermally responsive element 5.

  Also in these heat responsive elements 5A and 5B, when the heat responsive elements 5A and 5B are thermally deformed in an inverted shape, the first protrusions 53a and 53b abut against the PTC thermistor 6 at a plurality of locations, and the heat responsive elements 5A. And 5B body part. Therefore, the center 54 of the thermally responsive elements 5A and 5B is not subjected to the stress associated with the contact between the thermally responsive elements 5A and 5B and the PTC thermistor 6, and is locally present at the center 54 of the thermally responsive elements 5A and 5B. Deformation is avoided. Furthermore, since a plurality of first projecting portions 53a and 53b are formed in a scattered manner, a stress dispersing action can be obtained as in the case of the thermally responsive element 5 shown in FIGS. By further increasing the number of points of the first protrusion 53b, the contact area between the first protrusion 53b and the PTC thermistor 6 is increased, and a further stress dispersing action is obtained. Further, the dot-like first protrusion 53a and the first protrusion 53b have an influence on the temperature characteristics (reversal operation temperature and normal rotation return temperature) of the thermally responsive element 5 and the like as compared with the annular first protrusion 53. Therefore, the design is easy.

  In the thermally responsive element 5 </ b> C shown in FIG. 7C, a bead-shaped first protrusion 53 c is formed continuously in the short direction of the breaker 1. The first protrusion 53 c is formed at a location away from the center 54 of the thermally responsive element 5.

  In this thermal response element 5C, when the thermal response element 5 is thermally deformed into an inverted shape, the thermal response element 5 comes into contact with the first projecting portion 53c and the center 54, that is, the PTC thermistor 6 in two regions, and the thermal response. The body portion of the element 5 is supported. Thereby, the stress applied to the thermally responsive element 5 is dispersed. In this modification, since the first protrusion 53c is formed in a continuous region in a bead shape, the contact area between the first protrusion 53c and the PTC thermistor 6 is increased, and the stress dispersing action Is more prominently obtained.

(Modification 2)
FIG. 8 shows a PTC thermistor 6 </ b> A that is a modification of the PTC thermistor 6. A PTC thermistor 6A shown in FIG. 8 has a second protrusion 62 protruding on the surface of the heat responsive element 5 on the surface 61 facing the heat responsive element 5, so that the PTC thermistor shown in FIG. 6 is different.

  The second protrusion 62 is formed around the center 63 of the surface 61 of the PTC thermistor 6A. Since the center 63 of the PTC thermistor 6 </ b> A substantially coincides with the center 54 of the thermal response element 5, the second protrusion 62 is substantially equivalent to being formed around the center 54 of the thermal response element 5. can do.

  The 2nd protrusion part 62 is continuously formed in cyclic | annular form. Since such a PTC thermistor 6A has a symmetrical shape with respect to the center 63, there is no need to consider the directionality when incorporating the resin base 71, and the assembly process of the breaker 1 can be simplified. Is possible. The center of the second protrusion 62 formed in an annular shape substantially coincides with the center 54 of the thermally responsive element 5 in plan view. In the present embodiment, the first projecting portion 53 is continuously formed once, but may be partially interrupted. A plurality of second projecting portions 62 may be formed concentrically. In this case, the protrusion amount of the second protrusion 62 that is further away from the center 54 of the thermally responsive element 5 is set to be large.

  When the thermally responsive element 5 is thermally deformed into an inverted shape, the second protrusion 62 contacts the thermally responsive element 5 and supports the thermally responsive element 5. Accordingly, as in the present embodiment, the center 54 of the thermal reaction element 5 is separated from the PTC thermistor 6 in a floating state, and the thermal reaction element 5 and the PTC thermistor are separated from the center 54 of the thermal reaction element 5. Stress associated with the contact with 6A is not applied, and local deformation at the center 54 of the thermally responsive element 5 is avoided.

  On the other hand, in the thermally responsive element 5, the stress associated with the contact with the PTC thermistor 6 </ b> A is applied to the annular portion that is in contact with the second protrusion 62 of the PTC thermistor 6 </ b> A. However, since the second protrusion 62 is disposed at a location away from the center 54 of the thermally responsive element 5, the stress applied to the portion in contact with the second protrusion 62 is dispersed. Furthermore, in this embodiment, since the 2nd protrusion part 62 is formed in the cyclic | annular continuous area | region, the dispersion | distribution effect | action of the said stress is acquired more notably.

  The amount of protrusion of the second protrusion 62 may be set such that the center 54 slightly contacts the center 63 of the PTC thermistor 6A when the thermoresponsive element 5 is thermally deformed into an inverted shape. This is because even in this case, part of the stress applied to the thermally responsive element 5 can be dispersed by the second projecting portion 62 and the stress applied to the center 54 of the thermally responsive element 5 can be reduced.

  According to the breaker 1 provided with the PTC thermistor 6A of the present modification, the second projecting portion 62 that projects toward the thermally responsive element 5 is formed on the PTC thermistor 6A. The second protrusion 62 comes into contact with the heat-responsive element 5 when the heat-sensitive element 5 is away from the heat-sensitive element, that is, when the heat-responsive element 5 has an inverted shape. Therefore, by providing the second projecting portion 62 away from the center 54 where stress is likely to concentrate in the thermal actuator 5, the stress generated in the thermal actuator 5 can be easily dispersed, and the normal rotation return temperature in the finished product of the breaker 1. Can be kept low. Therefore, while using the thin thermal actuator 5, it is possible to return the thermal actuator 5 to normal rotation at a desired temperature in the finished breaker 1 without setting the radius of curvature small. Thereby, it becomes possible to achieve both reduction in size of the breaker 1 and improvement in yield.

  According to the breaker 1, since the second projecting portion 62 is formed around the center 54 of the thermally responsive element 5, the stress generated in the thermally responsive element 5 can be dispersed at the center 54 where stress tends to concentrate. Thereby, the normal rotation return temperature in the finished product of the breaker 1 can be easily maintained low.

  According to the breaker 1, since the thermally responsive element 5 at the time of thermal deformation is supported by the second projecting portion 62 formed continuously in an annular shape, the contact between the thermally responsive element 5 and the second projecting portion 53. The area can be increased, and the stress at the center 54 of the thermally responsive element 5 can be more effectively distributed.

  FIG. 9 shows PTC thermistors 6B, 6C and 6D which are modifications of the PTC thermistor 6A. In the PTC thermistor 6B shown in FIG. 9A, three dot-shaped second protrusions 62b are formed, and in the PTC thermistor 6C shown in FIG. Two projecting portions 62c are formed in a dotted manner. The second protrusions 62b and 62c are formed around the center 63 of the PTC thermistors 6B and 6C. More specifically, the second protrusions 62b and 62c are arranged at equal intervals at substantially equal distances from the centers 63 of the PTC thermistors 6B and 6C, that is, the centers 54 of the thermal actuators 5.

  Also in these PTC thermistors 6B and 6C, when the thermally responsive element 5 is thermally deformed into an inverted shape, the second protrusions 62b and 62c abut against the thermally responsive element 5 and support the main body portion of the thermally responsive element 5. To do. Therefore, the center 54 of the thermal response element 5 is not subjected to stress due to the contact between the thermal response element 5 and the PTC thermistor 6, and local deformation at the center 54 of the thermal response element 5 is avoided. Further, since a plurality of second projecting portions 62b and 62c are formed in a scattered manner, a stress dispersing action can be obtained in the same manner as the PTC thermistor 6 shown in FIG. By further increasing the number of points of the second projecting portion 62c, the contact area between the thermally responsive element 5 and the second projecting portion 53 is increased, and a further stress dispersing action is obtained.

  In the PTC thermistor 6D shown in FIG. 9C, a bead-shaped second protrusion 62d is continuously formed. The second projecting portion 62d is formed at a location away from the center 63 of the PTC thermistor 6D, that is, the center 54 of the thermally responsive element 5.

  In this PTC thermistor 6D, when the thermoresponsive element 5 is thermally deformed in an inverted shape, the thermoresponsive element 5 abuts the PTC thermistor 6D at the second protrusion 62c and the center 63, that is, in two regions, and is thermally responsive. The body portion of the element 5 is supported. Thereby, the stress applied to the thermally responsive element 5 is dispersed. In the present modification, since the second projecting portion 62d is formed in a region that is continuous in a bead shape, the contact area between the thermally responsive element 5 and the second projecting portion 53 is increased, and the stress is dispersed. Is more prominently obtained.

  The second protrusions 62, 62b, 62c or 62d may be used in combination with the first protrusions 53, 53a, 53b or 53c shown in FIGS. In this case, the distance from the center 54 of the thermally responsive element 5 such as the first protrusion 53 and the second protrusion 62 is set so that the first protrusion 53 and the second protrusion 62 do not contact each other. It is preferable to adjust appropriately.

  Note that the present invention is not limited to the configuration of the above-described embodiment, and at least the first projecting portion 53 projecting to the side opposite to the movable piece 4 is formed on the thermally responsive element 5 or the PTC thermistor 6 is formed. The 2nd protrusion part 62 which protrudes in the heat-responsive element 5 side should just be formed.

  In the breaker 1, the PTC thermistor 6 may be omitted. In this case, when the thermally responsive element 5 has an inverted shape, the first protrusion 53 and the like abut on the surface of the component on the opposite side of the movable piece 4, for example, the resin base 71. Further, instead of the first protrusion 53 or in addition to the first protrusion 53, a protrusion equivalent to the second protrusion 62 may be formed on the surface of the resin base 71.

  Moreover, in FIG. 1 etc., the movable piece 4 is a form which has the structure of the through-hole 45, the step bending part 46, and the constriction part 49, However, Any or all of these structures may be abbreviate | omitted. . For example, when the through hole 45 is omitted, the protrusion 74a of the resin base 71 is also omitted. Further, when the stepped bending portion 46 is omitted, the terminal 41 has a flat shape with respect to the contact portion 42. In this configuration, by omitting the step bending portion 46, the size of the movable piece 4 and the resin base 71 in the longitudinal direction can be reduced, and the breaker 1 can be further reduced in size. Further, when the constricted portion 49 is omitted, the movable piece 4 is formed with an equal width from the contact portion 42 to the terminal 41, and the shape of the positioning portion 75 of the resin base 71 is changed accordingly. As described above, the shapes of the contact portion 42 of the movable piece 4, the contact portion 74 of the resin base 71, the contact portion 79 of the cover member 72, and the like are not limited to those shown in FIG. is there. Further, the shapes of the thermally responsive element 5, the PTC thermistor 6, the storage portion 73, and the like are not limited to those shown in FIG. Moreover, the structure which arrange | positions another component between the thermoresponsive element 5 and the PTC thermistor 6 may be sufficient. In this case, instead of the first protrusion 53 or in addition to the first protrusion 53, a protrusion equivalent to the second protrusion 62 may be formed on the surface of the separate part.

  Further, the number of protrusions 24a provided on the support portion 23 is not particularly limited. For example, another protrusion may be added to a location adjacent to the fixed contact 21, the center portion of the support portion 23, or the like. Furthermore, the structure which arrange | positions another component between the PTC thermistor 6 and the fixed piece 2 may be sufficient. In this case, the support portion 23 supports the PTC thermistor 6 via the separate part. Moreover, in the support part 23, one part or all protrusions may be abbreviate | omitted.

  Moreover, the joining method of the resin base 71 and the cover member 72 is not limited to ultrasonic welding, and can be appropriately applied as long as both are firmly joined. For example, a liquid or gel adhesive may be applied, filled, and cured to bond them together. Further, the case 7 is not limited to the form constituted by the resin base 71 and the cover member 72 and the like, but may be any form as long as the movable piece 4 is sandwiched and held by two or more parts. In this case, one is the first case and the other is the second case. In joining the resin base 71 and the cover member 72, a method such as caulking can be used. Such a technique is particularly effective when a metal is disposed at the joint between the two.

  Further, as shown in JP-A-2005-203277, the movable piece 4 is structurally separated into the terminal 41 side and the movable contact 3 side in the contact portion 42 or the vicinity thereof. The invention may be applied. Further, the arm terminal and the movable arm may be fixed by welding or the like. In this case, the contact portion 42 and the terminal 41 may be insert-molded in the resin base 71 together with the fixed piece 2 and the like. Furthermore, the present invention can be applied to a form having a pair of fixed contacts and a pair of movable contacts, and the movable piece being supported by a case at the center.

  Further, the breaker 1 of the present invention can be widely applied to secondary battery packs, safety circuits for electric devices, and the like. FIG. 10 shows the secondary battery pack 100. The secondary battery pack 100 includes a secondary battery 101 and a breaker 1 provided in the output terminal circuit of the secondary battery 101. FIG. 11 shows a safety circuit 102 for electrical equipment. The safety circuit 102 includes a breaker 1 in series in the output circuit of the secondary battery 101.

  A breaker equipped with a thermally responsive element based on the specifications shown in Table 1 was prototyped, and the reversal operation temperature and the normal rotation return temperature were measured. Each temperature was measured in the heat-responsive element single body and breaker finished product before incorporating in a breaker. In each specification, the material of the thermally responsive element is the same.

  For the breaker of Comparative Example 1, a conventional thermoresponsive element having a thickness of T1, a radius of curvature of R1, and no first protrusion was used. In contrast to the comparative example 1, the specification in which the thickness of the thermally responsive element is T2 (T2 <T1) is the comparative example 2. In Comparative Example 2, as the thickness of the thermally responsive element is reduced, the holding force for holding the vicinity of the tip of the movable piece in a non-conductive state decreases, and the normal rotation return temperature in the breaker finished product is further increased. Transition to high temperature. Compared to Comparative Example 2, Comparative Example 3 has a specification in which the radius of curvature is R2 (R2 <R1) so that the normal rotation return temperature of the finished breaker product is equivalent to that of Comparative Example 1. In Comparative Example 3, with the decrease in the radius of curvature, the normal rotation recovery temperature in the thermal response element alone and the breaker finished product is lowered, and the yield is deteriorated.

  Example 1 is a specification in which a first protrusion is formed with respect to Comparative Example 2, and Example 2 is a specification in which a second protrusion is formed with respect to Comparative Example 2. In any of the examples, the difference between the normal rotation return temperature in the breaker finished product and the normal rotation return temperature in the thermal response element alone was maintained equal to that in Comparative Example 1, and the thickness of the thermal response element was reduced. The decrease in holding power associated with is eliminated. Moreover, in any Example, since a curvature radius is R1, the yield is maintained equivalent to the comparative example 1.

DESCRIPTION OF SYMBOLS 1 Breaker 2 Fixed piece 3 Movable contact 4 Movable piece 5, 5A, 5B, 5C Thermally responsive element 6, 6A, 6B, 6C, 6D PTC thermistor 7 Case 8 Cover piece 21 Fixed contact 53, 53a, 53b, 53c 1st Projection 54 Center 62, 62b, 62c, 62d Second Projection 101 Secondary Battery 102 Safety Circuit

Claims (10)

A fixed piece having a fixed contact;
A movable piece having a movable contact, and pressing the movable contact against the fixed contact;
In a breaker including a thermally responsive element that operates the movable piece so that the movable contact is separated from the fixed contact by being deformed with a temperature change,
The breaker according to claim 1, wherein the thermally responsive element is formed with a first protruding portion that protrudes on a side opposite to the movable piece.   The breaker according to claim 1, wherein the first protrusion is formed around a center of the thermally responsive element.   The breaker according to claim 1, wherein the first projecting portion is continuously formed in an annular shape.   The breaker according to any one of claims 1 to 3, wherein a plurality of the first protrusions are formed in a dotted manner. A fixed piece having a fixed contact;
A movable piece having a movable contact, and pressing the movable contact against the fixed contact;
A thermally responsive element that operates the movable piece so that the movable contact is separated from the fixed contact by being deformed with a temperature change;
A positive characteristic that is inserted between the thermally responsive element and the fixed piece and electrically connects the movable piece and the fixed piece via the thermally responsive element when the movable contact is separated from the fixed contact. In a breaker equipped with a thermistor,
The breaker according to claim 1, wherein the positive temperature coefficient thermistor is formed with a second projecting portion projecting toward the thermoresponsive element.   The breaker according to claim 5, wherein the second protrusion is formed around a center of the thermally responsive element.   The breaker according to claim 5 or 6, wherein the second projecting portion is formed continuously in an annular shape.   The breaker according to any one of claims 5 to 6, wherein a plurality of the second protrusions are formed in a dotted manner.   A safety circuit for electrical equipment, comprising the breaker according to any one of claims 1 to 8.   A secondary battery circuit comprising the breaker according to any one of claims 1 to 8.

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