Breakers, safety circuits and secondary battery packs

Abstract

To provide a breaker which can be assembled so that a fixed contact and a movable contact become an appropriate contact state while suppressing plastic deformation of a movable piece.SOLUTION: A breaker includes, a fixed contact, a movable piece 4 having an elastic part 44 and a movable contact 41 on one end 44e of the elastic part 44, a thermally-actuated element deformed accompanied by temperature change, a case body which is formed with a storage recess for storing the fixed contact, the movable piece 4 and the thermally-actuated element, and a lid member 8 which is integrated with the movable piece 4, is fastened to the case body and covers the storage recess. The lid member 8 has a fastened surface 82 fastened to the case body, the elastic part 44 projects to the side of the case body from the fastened surface 82 with a first projection amount P1, and the lid member 8 has a projection part 84 projecting to the side of the case body from the fastened surface 82 with a second projection amount P2 larger than the first projection amount P1.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a small breaker or the like to be built into an electric device or the like. [Background technology]

[0002] 2. Description of the Related Art Conventionally, breakers have been used as protective devices (safety circuits) for secondary batteries, motors, heaters, and the like of various electrical devices (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2011 / 105175 publication Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned Patent Document 1 discloses a breaker in which a cover member is ultrasonically welded to a case body that houses a thermally responsive element and a movable piece.

[0005] However, the movable piece is handled as a single unit in the process prior to being housed in the case body, and there is a risk that the elastic portion will undergo plastic deformation due to inadvertent contact, etc. In addition, it is difficult to accurately position the movable piece relative to the case body, which makes it difficult to assemble the breaker so that the fixed contact and movable contact are in proper contact with each other.

[0006] The present invention has been devised in consideration of the above-mentioned circumstances, and has as its main object to provide a breaker that can be assembled so that the fixed contact and the movable contact are in proper contact while suppressing plastic deformation of the movable piece. [Means for solving the problem]

[0007] The present invention is a breaker comprising: a fixed contact; a movable piece having a plate-like elastic portion that elastically deforms and a movable contact at one end of the elastic portion, and pressing the movable contact into contact with the fixed contact; a thermally responsive element that deforms in response to a change in temperature, thereby transitioning the movable piece from a conductive state in which the movable contact is in contact with the fixed contact to a cut-off state in which the movable contact is separated from the fixed contact; a first resin case having an accommodating recess for accommodating the fixed contact, the movable piece, and the thermally responsive element; and a second resin case that is integrated with the movable piece and fixed to the first resin case to cover the accommodating recess, wherein the second resin case has a fixing surface that is fixed to the first resin case, the elastic portion protrudes from the fixing surface toward the first resin case by a first protrusion amount, and the second resin case has a protrusion that protrudes from the fixing surface toward the first resin case by a second protrusion amount greater than the first protrusion amount.

[0008] In the breaker according to the present invention, it is preferable that the protrusions are provided on both sides in the short direction of the movable piece, sandwiching the movable contact.

[0009] In the breaker according to the present invention, it is preferable that the first resin case is formed with a recess into which the protrusion fits.

[0010] In the breaker according to the present invention, it is preferable that the protrusion overlaps with the one end portion at least in part when viewed in the short side direction of the movable piece.

[0011] In the breaker according to the present invention, it is preferable that at least a part of the protrusion is formed further outboard in the longitudinal direction of the movable piece than one end of the elastic portion.

[0012] The present invention is a safety circuit for an electrical device, comprising the above-mentioned breaker.

[0013] The present invention is a secondary battery pack including the above-mentioned breaker. Effect of the Invention

[0014] In the breaker of the present invention, the movable piece is integrated with the second resin case, so that the risk of the elastic part being plastically deformed in the process before being housed in the first resin case is suppressed. In addition, the second resin case is formed with a protruding part that protrudes from the fixing surface with the first resin case by a second protruding amount that is larger than the first protruding amount of the elastic part, so that the elastic part is guarded by the protruding part, and plastic deformation is further suppressed. In addition, the protruding part suppresses contact between the elastic part and the first resin case in the initial stage of assembling the second resin case to the first resin case, so that the fixed contact and the movable contact can be assembled in a proper contact state. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a perspective view of a breaker manufactured according to the present invention in an unassembled state; [Diagram 2] FIG. 2 is a cross-sectional view showing the breaker in a normal charging or discharging state. [Diagram 3] 4 is a cross-sectional view showing the breaker in an overcharged state or during an abnormality. FIG. [Figure 4] FIG. 4 is a perspective view showing a lid member in which a movable piece and a cover piece are embedded. [Diagram 5] FIG. 4 is a perspective view showing a case body in which a fixing piece is embedded. [Figure 6] FIG. 4 is a cross-sectional view of a lid member in which a movable piece and a cover piece are embedded. [Figure 7] FIG. 2 is a plan view showing the configuration of a secondary battery pack including the breaker of the present invention. [Figure 8] FIG. 2 is a circuit diagram of a safety circuit including the breaker of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A breaker according to an embodiment of the present invention will be described with reference to the drawings. Figures 1 to 3 show the configuration of a breaker 1 manufactured according to the present invention. The breaker 1 is mounted on an electric device, a secondary battery pack, etc., and protects the electric device, the secondary battery pack, etc. from an excessive temperature rise or an overcurrent.

[0017] The breaker 1 is composed of a fixed piece 2 having a fixed contact 21, a movable piece 4 having a movable contact 41 at one end, a thermally responsive element 5 that deforms with temperature changes, a PTC (Positive Temperature Coefficient) thermistor 6, and a resin case 10 that houses the fixed piece 2, the movable piece 4, the thermally responsive element 5, and the PTC thermistor 6. The resin case 10 is composed of a case body (first resin case) 7, a cover member (second resin case) 8 attached to the upper surface of the case body 7, and the like.

[0018] The fixed piece 2 is formed, for example, by pressing a metal plate whose main component is copper or the like (other metal plates include copper-titanium alloy, nickel silver, brass, etc.), and is embedded in the case body 7 by insert molding. One end of the fixed piece 2 is formed with a terminal 22 that is electrically connected to an external circuit, and the other end is formed with a support portion 23 that supports the PTC thermistor 6. The terminal 22 protrudes to the outside of the case body 7. The PTC thermistor 6 is placed on and supported by convex projections (dowels) 24 formed in three places on the support portion 23 of the fixed piece 2. By bending the fixed piece 2 in a stepped shape, the fixed contacts 21 and the support portions 23 are arranged in staggered positions, and a space for accommodating the PTC thermistor 6 can be easily secured.

[0019] The fixed contact 21 is formed at a position facing the movable contact 41 by cladding, plating, welding, coating, or the like of a material with good conductivity such as silver, nickel, nickel-silver alloy, copper-silver alloy, gold-silver alloy, etc., and is exposed from a part of an opening 73a formed inside the case body 7. The terminal 22 protrudes outward from an edge of the case body 7. The support portion 23 is exposed from an opening 73d formed inside the case body 7.

[0020] In this application, unless otherwise specified, the surface of the fixed piece 2 on which the fixed contact 21 is formed (i.e., the upper surface in FIG. 1) is described as the first surface, and the opposite surface is described as the second surface. The same applies to other components, such as the movable piece 4, the thermally responsive element 5, the PTC thermistor 6, the resin case 10, etc.

[0021] The movable piece 4 is formed into an arm shape symmetrical about the center line in the longitudinal direction by pressing a plate-shaped metal material mainly composed of copper etc. A part of the movable piece 4 (a fixed part 43 described later) is embedded in the cover member 8 by insert molding and is integrated with the cover member 8.

[0022] A movable contact 41 is formed at one end in the longitudinal direction of the movable piece 4. The movable contact 41 is made of, for example, the same material as the fixed contact 21, and is joined to one end of the movable piece 4 by welding, cladding, crimping, or other techniques.

[0023] A terminal 42 that is electrically connected to an external circuit is formed on the other end of the movable piece 4. The terminal 42 protrudes outward from the edge of the cover member 8. A fixed portion 43 that is embedded in and fixed to the cover member 8 is provided between the movable contact 41 and the terminal 42. The fixed portion 43 is disposed on the terminal 42 side.

[0024] The movable piece 4 has an elastic portion 44 between the movable contact 41 and the fixed portion 43. The elastic portion 44 extends from the fixed portion 43 toward the movable contact 41. The movable piece 4 is cantilevered by the cover member 8 at the fixed portion 43 on the base end side of the elastic portion 44, and in this state, the elastic portion 44 elastically deforms toward the first surface, so that the movable contact 41 formed at the tip of the elastic portion 44 is pressed against the fixed contact 21 and comes into contact with it, allowing electricity to flow between the fixed piece 2 and the movable piece 4.

[0025] It is desirable that the movable piece 4 is curved or bent by pressing at the elastic portion 44. The degree of curvature or bending is not particularly limited as long as it can accommodate the thermally responsive element 5, and may be set appropriately taking into consideration the elastic force at the operating temperature and the return temperature, the pressing force of the contacts, and the like. In addition, a pair of protrusions (contact portions) 44a, 44b are formed on the second surface of the elastic portion 44 so as to face the thermally responsive element 5. The protrusions 44a, 44b come into contact with the thermally responsive element 5, and deformation of the thermally responsive element 5 is transmitted to the elastic portion 44 via the protrusions 44a, 44b (see Figs. 1, 2, and 3).

[0026] The thermally responsive element 5 is disposed between the movable piece 4 and the PTC thermistor 6. That is, the thermally responsive element 5 is placed on a first surface of the PTC thermistor 6 described later. The thermally responsive element 5 changes its shape in response to a change in temperature, thereby shifting the state of the movable piece 4 from a conductive state in which the movable contact 41 contacts the fixed contact 21 to a cut-off state in which the movable contact 41 is separated from the fixed contact 21. The thermally responsive element 5 is formed into a plate shape by laminating thin plate materials with different thermal expansion coefficients, and has an initial shape in which the cross section is curved in an arc shape. When the reversal operating temperature is reached due to overheating, the curved shape of the thermally responsive element 5 reversely warps with a snap motion, and returns to its original shape when the temperature falls below the normal rotation return temperature due to cooling. The initial shape of the thermally responsive element 5 can be formed by pressing. The material and shape of the thermally responsive element 5 are not particularly limited, as long as the elastic portion 44 of the movable piece 4 is pushed up by the reverse warping deformation of the thermally responsive element 5 at the desired temperature and returns to its original shape by the elastic force of the elastic portion 44. However, a rectangular shape is preferable from the standpoint of productivity and efficiency of the reverse warping deformation.

[0027] As the material of the thermally responsive element 5, a laminate of two kinds of materials with different thermal expansion coefficients made of various alloys such as nickel silver, brass, and stainless steel is used in combination according to the required conditions. For example, as a material of the thermally responsive element 5 that can obtain a stable reverse operation temperature and normal rotation return temperature, a combination of a copper-nickel-manganese alloy on the high expansion side and an iron-nickel alloy on the low expansion side is preferable. Furthermore, from the viewpoint of chemical stability, a more preferable material is a combination of an iron-nickel-chromium alloy on the high expansion side and an iron-nickel alloy on the low expansion side. Furthermore, from the viewpoint of chemical stability and processability, a more preferable material is a combination of an iron-nickel-chromium alloy on the high expansion side and an iron-nickel-cobalt alloy on the low expansion side.

[0028] When the movable piece 4 is in an interrupted state, the PTC thermistor 6 conducts the fixed piece 2 and the movable piece 4 through the thermally responsive element 5. The PTC thermistor 6 is disposed between the fixed piece 2 and the thermally responsive element 5. That is, the support part 23 of the fixed piece 2 is located directly below the thermally responsive element 5, sandwiching the PTC thermistor 6. When the current between the fixed piece 2 and the movable piece 4 is interrupted by the reverse warpage deformation of the thermally responsive element 5, the current flowing through the PTC thermistor 6 increases. The PTC thermistor 6 can be selected according to the operating current, operating voltage, operating temperature, return temperature, and other requirements as long as it is a positive characteristic thermistor that increases in resistance with increasing temperature to limit the current, and the material and shape are not particularly limited as long as these various characteristics are not impaired. In this 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.

[0029] The case body 7 and the lid member 8 constituting the resin case 10 are molded from thermoplastic resins such as flame-retardant polyamide, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT), etc. Materials other than resins may be used as long as they have properties equal to or better than those of the above-mentioned resins.

[0030] An accommodating recess 73 is formed on the first surface side of the case body 7 as an internal space for accommodating the fixed contact 21, the movable piece 4, the thermally responsive element 5, the PTC thermistor 6, and the like. The accommodating recess 73 has an opening 73a for accommodating the fixed contact 21 and the movable piece 4, an opening 73c for accommodating the movable piece 4 and the thermally responsive element 5, and an opening 73d for accommodating the PTC thermistor 6. The edges of the movable piece 4 and the thermally responsive element 5 incorporated in the case body 7 are abutted by a frame constituting the accommodating recess 73, respectively, and are guided during reverse warpage deformation of the thermally responsive element 5. That is, the accommodating recess 73 accommodates the movable piece 4 and the thermally responsive element 5 in a deformable manner.

[0031] The lid member 8 is configured to cover the accommodating recess 73. The lid member 8 may be configured to cover at least a portion of the accommodating recess 73. A cover piece 9 made of a metal plate mainly composed of copper or the like, stainless steel or the like is embedded in the lid member 8 by insert molding. The cover piece 9 is embedded in the lid member 8 together with the fixed portion 43 of the movable piece 4 in a state of contact with a first surface of the fixed portion 43. The cover piece 9 restricts the movement of the movable piece 4, and contributes to the miniaturization of the breaker 1 while increasing the rigidity and strength of the lid member 8 and thus the resin case 10 serving as a housing.

[0032] The case body 7 and the cover member 8 are formed by injection molding using the above-mentioned resin material. As already described, the fixed piece 2 is inserted into the case body 7, and the movable piece 4 and the cover piece 9 are inserted into the cover member 8.

[0033] 1, the cover member 8 is attached to the case body 7 so as to close the openings 73a, 73c, etc. of the case body 7 housing the fixed piece 2, the movable piece 4, the thermally responsive element 5, the PTC thermistor 6, etc. The housing recess 73 is covered by the cover member 8. The case body 7 and the cover member 8 are joined by, for example, ultrasonic welding. In this way, the resin case 10 is formed.

[0034] 2 and 3 show an outline of the operation of the breaker 1. FIG. 2 shows the operation of the breaker 1 in a normal charging or discharging state. In a normal charging or discharging state, the thermally responsive element 5 maintains its initial shape before reverse warping. The movable contact 41 is pressed toward the fixed contact 21 by the elastic part 44, so that the movable contact 41 and the fixed contact 21 come into contact with each other, and the fixed piece 2 and the movable piece 4 of the breaker 1 are brought into a conductive state via the elastic part 44 of the movable piece 4.

[0035] The elastic portion 44 of the movable piece 4 and the thermally responsive element 5 may be in contact with each other. In this case, the movable piece 4, the thermally 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 negligible compared to the amount of current flowing through the fixed contact 21 and the movable contact 41.

[0036] FIG. 3 shows the operation of the breaker 1 in an overcharged state or an abnormality. The thermally responsive element 5, which is a laminate of thin plates with different thermal expansion coefficients, deforms as the temperature rises so that the curved initial shape shown in FIG. 2 is corrected. Then, when the thermally responsive element 5 reaches the operating temperature, it snaps into a reverse warped shape as shown in FIG. 3. As a result, the thermally responsive element 5 comes into contact with the elastic part 44 of the movable piece 4, and the elastic part 44 is pushed up by the thermally responsive element 5, separating the fixed contact 21 from the movable contact 41. At this time, the current flowing between the fixed contact 21 and the movable contact 41 is cut off. Meanwhile, the thermally responsive element 5 comes into contact with the movable piece 4, and a small leakage current flows through the thermally responsive element 5 and the PTC thermistor 6. That is, the PTC thermistor 6 makes the fixed piece 2 and the movable piece 4 conductive through the thermally responsive element 5, which is causing the movable piece 4 to transition to an interrupted state. As long as such leakage current flows, the PTC thermistor 6 continues to generate heat, and the resistance value increases dramatically while maintaining the thermally responsive element 5 in a reversely warped state, so that the current does not flow through the path between the fixed contact 21 and the movable contact 41, and only the slight leakage current described above exists (forming a self-holding circuit). This leakage current can be used for other functions of the safety device.

[0037] When the overcharged state is released or the abnormal state is eliminated, the heat generation of the PTC thermistor 6 stops, the temperature of the thermally responsive element 5 returns to the normal rotation return temperature, and it returns to its original initial shape. Then, the elastic force of the elastic portion 44 of the movable piece 4 brings the movable contact 41 and the fixed contact 21 back into contact, the circuit is released from the interrupted state, and it returns to the conductive state shown in FIG. 2.

[0038] FIG. 4 shows the lid member 8 in which the movable piece 4 and the cover piece 9 are embedded. The movable piece 4 has a terminal 42 and a fixed portion 43. The fixed portion 43 is formed between the elastic portion 44 and the terminal 42. The fixed portion 43 is embedded in the resin that constitutes the lid member 8 together with the cover piece 9, and is fixed to the lid member 8. This integrates the movable piece 4, the cover piece 9, and the lid member 8. The fixed portion 43 in this embodiment is in contact with the cover piece 9. This stabilizes the attitude of the movable piece 4 relative to the lid member 8. In addition, since the movable piece 4 is integrated with the lid member 8, the risk of plastic deformation of the elastic portion in the process prior to being housed in the case body 7 is reduced.

[0039] The cover member 8 has an embedding portion 81 in which the fixed portion 43 of the movable piece 4 is embedded, a fixing surface 82 which is fixed to the case body 7, and an accommodating recess 83 which is recessed on the opposite side of the case body 7.

[0040] The embedded portion 81 protrudes toward the side of the case body 7 in order to embed the fixed portion 43. By embedding the fixed portion 43 in the embedded portion 81, the movable piece 4 is fixed at an accurate position relative to the cover member 8. The embedded portion 81 is formed extending in the short-side direction D1 of the movable piece 4 along the edge of the cover member 8 on the terminal 42 side. The embedded portion 81 in this embodiment extends to the edge of the cover member 8 in the short-side direction D1.

[0041] The fastening surface 82 is formed facing the case body 7. The tip surface of the embedded portion 81 constitutes a part of the fastening surface 82. The fastening surface 82 is preferably formed in a flat shape, but may be formed in a partially inclined shape as shown in FIG.

[0042] The accommodating recess 83 is recessed from the fixing surface 82 to accommodate the movable contact 41 and the elastic portion 44 of the movable piece 4. By forming the accommodating recess 83 in the cover member 8, the movable contact 41, the elastic portion 44 and the cover piece 9 are exposed to the internal space within the resin case 10.

[0043] 5 shows the case body 7 in which the fixing piece 2 is embedded. The case body 7 has a welding portion 74 and a fixing surface 75.

[0044] The welded portion 74 is disposed at a position facing the embedded portion 81 when the cover member 8 is attached to the case body 7. The welded portion 74 is formed in a flat shape from the end edge of the movable piece 4 in the longitudinal direction D2 of the case body 7 toward the accommodating recess 73. The welded portion 74 is welded to the embedded portion 81 and integrated with it.

[0045] The fixing surface 75 is disposed in a position and shape facing the fixing surface 82 when the cover member 8 is attached to the case body 7. The fixing surface 75 is welded and integrated with the fixing surface 82. The fixing surfaces 75 and 82 may be formed with projections and recesses that fit into each other.

[0046] The fixed contact 21 is disposed in a receiving recess 73 recessed from the fixing surface 75. This reduces the height of the breaker 1.

[0047] FIG. 6 shows a cross section parallel to the longitudinal direction D2 of the lid member 8 in which the movable piece 4 and the cover piece 9 are embedded.

[0048] The elastic portion 44 of the movable piece 4 protrudes from the fixing surface 82 toward the case body 7. More specifically, the movable contact 41 disposed at one end 44e of the elastic portion 44 protrudes from the fixing surface 82 around the elastic portion 44 by a first protrusion amount P1. As a result, the fixed contact 21 recessed from the fixing surface 75 and the movable contact 41 come into contact with each other with an appropriate pressure, and the contact pressure between them is reduced.

[0049] The cover member 8 has a protruding portion 84 that protrudes from the fixing surface 82 toward the case body 7. The protruding portion 84 protrudes from the fixing surface 82 around the elastic portion 44 toward the case body 7 by a second protruding amount P2 that is larger than the first protruding amount P1. In other words, the tip of the protruding portion 84 protrudes toward the case body 7 further than the movable contact 41.

[0050] The elastic portion 44 protruding from the fixing surface 82 of the cover member 8 towards the case body 7 is likely to come into contact with some member (e.g., the case body 7) or a part of the assembly device for the breaker 1 in a process prior to being housed in the case body 7, and may be plastically deformed by an external force accompanying such contact. For example, in a configuration in which the cover member 8 with the movable piece 4 embedded therein is wound into a coil as disclosed in Japanese Patent No. 3413167, the cover members 8 and the movable pieces 4 adjacent to each other in the radial direction may come into contact with each other, and the elastic portion 44 may be plastically deformed.

[0051] However, in the present breaker 1, the protruding portion 84 is formed on the cover member 8, protruding from the fixing surface 82 by a second protruding amount P2 larger than the first protruding amount P1 of the elastic portion 44, so that the elastic portion 44 is guarded by the protruding portion 84, and plastic deformation is further suppressed. In addition, the protruding portion 84 suppresses contact between the elastic portion 44 and the case body 7 in the initial stage of assembling the cover member 8 to the case body 7, so that the fixed contact 21 and the movable contact 41 can be assembled so as to be in an appropriate contact state.

[0052] It is preferable that the protrusions 84 are provided on both sides of the movable contact 41 in the short-side direction D1 of the movable piece 4. With this configuration, contact between the elastic part 44 and the case body 7 and the like is further suppressed, and plastic deformation of the elastic part 44 is further suppressed.

[0053] 5, it is preferable that a recess 76 is formed in the case body 7. The recess 76 is formed by being recessed from the fixing surface 75 at a position corresponding to the protrusion 84. More specifically, the recess 76 is provided on both sides in the short direction D1 across the fixed contact 21. When the cover member 8 is attached to the case body 7, the protrusion 84 fits into the recess 76. This allows the cover member 8 to be accurately positioned with respect to the case body 7.

[0054] 6, it is desirable that the protrusion 84 at least partially overlaps with one end 44e of the elastic part 44 in a side view seen from the short-side direction D1 of the movable piece 4. Such a protrusion 84 makes it even more effective to protect the elastic part 44.

[0055] Furthermore, it is preferable that at least a part of the protrusion 84 is formed outside the one end 44e of the elastic portion 44 in the longitudinal direction D2 of the movable piece 4. Such a protrusion 84 makes it possible to protect the elastic portion 44 even more effectively.

[0056] Although the breaker 1 of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment and may be modified and embodied in various forms.

[0057] That is, the breaker 1 of the present invention comprises at least the fixed contact 21, a movable piece 4 which is formed in a plate shape and has an elastically deformable elastic portion 44 and a movable contact 41 at one end 44e of the elastic portion 44, and which presses the movable contact 41 into contact with the fixed contact 21, a thermally responsive element 5 which deforms in response to a change in temperature to shift the movable piece 4 from a conductive state in which the movable contact 41 is in contact with the fixed contact 21 to a cut-off state in which the movable contact 41 is separated from the fixed contact 21, and a thermally responsive element 5 which is connected to the fixed contact 21 ... A breaker 1 is provided with a case body 7 having an accommodating recess 73 for accommodating an element 5, and a lid member 8 which is integrated with a movable piece 4 and fixed to the case body 7 to cover the accommodating recess 73, wherein the lid member 8 has a fixing surface 82 which is fixed to the case body 7, the elastic portion 44 protrudes from the fixing surface 82 toward the case body 7 by a first protrusion amount P1, and the lid member 8 has a protrusion 84 which protrudes from the fixing surface 82 toward the case body 7 by a second protrusion amount P2 which is greater than the first protrusion amount P1.

[0058] For example, the movable piece 4 may be formed from a laminated metal such as a bimetal or trimetal, so that the movable piece 4 and the thermally responsive element 5 are integrally formed. In this case, the structure of the breaker 1 etc. is simplified.

[0059] Furthermore, in this embodiment, a self-holding circuit using the PTC thermistor 6 is provided, but a configuration in which this configuration is omitted is also applicable.

[0060] The breaker 1 of the present invention can also be widely applied to secondary battery packs, safety circuits for electrical devices, etc. Fig. 7 shows a secondary battery pack 500. The secondary battery pack 500 includes a secondary battery 501 and a breaker 1 provided in an output circuit of the secondary battery 501. Fig. 8 shows a safety circuit 502 for electrical devices. The safety circuit 502 includes a breaker 1 in series in the output circuit of the secondary battery 501. The secondary battery pack 500 or safety circuit 502 including the breaker 1 can provide a secondary battery pack 500 or safety circuit 502 that can provide stable conduction even when used at extremely low temperatures. [Explanation of symbols]

[0061] 1: Breaker 4: Movable piece 5: Thermal response element 6: PTC thermistor 7: Case body (first resin case) 8: Lid member (second resin case) 10: Resin case 21: Fixed contact 41: Movable contact 44: Elastic part 44e: One end 73: Storage recess 75: Adhesive surface 76: Recess 77: Second recess 81: Buried section 82: Adhesive surface 83: Storage recess 500: Secondary battery pack 501: Secondary battery 502 :Safety circuit D1: Lateral direction D2: Longitudinal direction P1: 1st protrusion amount P2: 2nd protrusion amount

Claims

1. A fixed contact; a movable piece having an elastic portion formed in a plate shape, which elastically deforms, and a movable contact at one end of the elastic portion, the movable contact being pressed against the fixed contact to bring the movable contact into contact with the fixed contact; a thermally responsive element that deforms in response to a change in temperature to transition the movable piece from a conductive state in which the movable contact is in contact with the fixed contact to a cut-off state in which the movable contact is separated from the fixed contact; a first resin case having an accommodating recess formed therein for accommodating the fixed contact, the movable piece, and the thermally responsive element; a second resin case that is integrated with the movable piece and is fixed to the first resin case to cover the accommodating recess, the second resin case has a fastening surface to be fastened to the first resin case, the elastic portion protrudes from the fastening surface toward the first resin case by a first protrusion amount, the second resin case has a protruding portion that protrudes from the fastening surface toward the first resin case by a second protruding amount that is greater than the first protruding amount, The protrusions are provided on both sides of the movable contact in a short direction of the movable piece. breaker.

2. A fixed contact; a movable piece having an elastic portion formed in a plate shape, which elastically deforms, and a movable contact at one end of the elastic portion, the movable contact being pressed against the fixed contact to bring the movable contact into contact with the fixed contact; a thermally responsive element that deforms in response to a change in temperature to transition the movable piece from a conductive state in which the movable contact is in contact with the fixed contact to a cut-off state in which the movable contact is separated from the fixed contact; a first resin case having an accommodating recess formed therein for accommodating the fixed contact, the movable piece, and the thermally responsive element; a second resin case that is integrated with the movable piece and is fixed to the first resin case to cover the accommodating recess, the second resin case has a fastening surface to be fastened to the first resin case, the elastic portion protrudes from the fastening surface toward the first resin case by a first protrusion amount, the second resin case has a protruding portion that protrudes from the fastening surface toward the first resin case by a second protruding amount that is greater than the first protruding amount, The protruding portion overlaps with the one end portion at least in part when viewed from a short side direction of the movable piece. breaker.

3. The breaker according to claim 1 , wherein the first resin case has a recess into which the protrusion fits.

4. A breaker as described in any of claims 1 to 3, wherein at least a portion of the protrusion is formed longitudinally outside the movable piece further than the one end of the elastic portion.

5. A safety circuit for electrical equipment comprising a breaker as described in any one of claims 1 to 4.

6. A secondary battery pack equipped with a breaker described in any one of claims 1 to 4.

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