Circuit breakers, safety circuits, and secondary battery packs

Abstract

The circuit breaker (1) comprises: a fixed plate (2) having a fixed contact (21); a movable plate (4) having a movable contact (41); a thermally actuated element (5) that deforms with temperature changes, thereby transferring the movable plate (4) from a conducting state to an open state; a positive characteristic thermistor (6) that makes the fixed plate (2) and the movable plate (4) conduct when the movable plate (4) is in the open state; and a housing (10) that houses the fixed plate (2), the movable plate (4), the thermally actuated element (5), and the positive characteristic thermistor (6). The thermally actuated element (5) is disposed between the movable plate (4) and the positive characteristic thermistor (6). The housing (10) has a bottom surface (72). When the side with the movable contact (41) in the long side direction of the movable plate (4) is taken as the front side, the positive characteristic thermistor (6) is housed in the housing (10) in a backward tilted position relative to the bottom surface (72).

Description

Technical Field

[0001] This invention relates to small circuit breakers, etc., that are built into secondary battery packs or other electrical equipment. Background Technology

[0002] In the prior art, circuit breakers are known to include a movable piece, a thermally actuated element, a positive characteristic thermistor, and a housing, wherein the movable piece has fixed contacts and movable contacts (for example, see Patent Document 1). Prior technology documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-149841 Summary of the Invention (The problem the invention aims to solve)

[0004] With the miniaturization of electrical equipment in recent years, there is a growing demand for miniaturized circuit breakers, especially in terms of height. This reduction in height can be achieved, for example, by minimizing the gap between the movable contact and the thermally actuated element near the movable contact.

[0005] However, with the aforementioned gap reduced, the thermal actuator may come into contact with the movable piece and be affected by the elastic force of the movable piece before thermal deformation begins, thus hindering the rapid (snap) deformation of the thermal actuator. As a result, the operating temperature of the circuit breaker may fluctuate.

[0006] The present invention is made in view of the above facts, and its main objective is to provide a circuit breaker that achieves a compact design with a small gap between the movable piece and the thermally actuated element, while also easily ensuring a stable operating temperature. (Technical solution used to solve the problem)

[0007] This invention provides a circuit breaker comprising: a fixed piece having a fixed contact; a movable piece having a movable contact, wherein the movable contact is pressed against the fixed contact to make contact with the fixed contact; a thermally actuated element that deforms with temperature changes, thereby transferring the movable piece from a conducting state where the movable contact is in contact with the fixed contact to an open state where the movable contact is separated from the fixed contact; a positive characteristic thermistor that, when the movable piece is in the open state, makes the fixed piece and the movable piece conduct; and a housing that accommodates the fixed piece, the movable piece, the thermally actuated element, and the positive characteristic thermistor, wherein the thermally actuated element is disposed between the movable piece and the positive characteristic thermistor, the housing having a bottom surface, wherein, when the side of the movable piece with the movable contact is taken as the front side in the long side direction of the movable piece, the positive characteristic thermistor is arranged in a backward tilted position relative to the bottom surface of the housing.

[0008] Preferably, based on the circuit breaker involved in the present invention, the fixing plate has a support surface that abuts against the bottom surface of the positive characteristic thermistor and is used to support the positive characteristic thermistor. The support surface is configured in a backward tilted position relative to the bottom surface of the housing.

[0009] Preferably, based on the circuit breaker involved in the present invention, the support surface includes a first protrusion projecting toward the side of the positive characteristic thermistor.

[0010] Preferably, based on the circuit breaker involved in the present invention, the support surface includes a second protrusion protruding toward the positive characteristic thermistor at a position further rearward than the first protrusion, wherein the protrusion height of the first protrusion is greater than the protrusion height of the second protrusion.

[0011] Preferably, based on the circuit breaker involved in the present invention, the fixing piece has a support portion, the support portion includes the support surface and extends along the long side direction of the movable piece, and the fixing piece is embedded in the housing in a rearward tilted position relative to the bottom surface of the housing.

[0012] Preferably, based on the circuit breaker involved in the present invention, the fixed piece has a support portion, the support portion includes the support surface and extends along the long side of the movable piece, and the thickness of the support portion decreases towards the rear.

[0013] The safety circuit for electrical equipment of the present invention includes the circuit breaker.

[0014] The secondary battery pack for electrical equipment of the present invention includes the circuit breaker. (Invention Effects)

[0015] Regarding the circuit breaker of the present invention, a thermally actuated element is disposed between a movable piece and a positive characteristic thermistor, and when the side with the movable contact is taken as the front side in the long side direction of the movable piece, the positive characteristic thermistor is housed in a rearward tilted position relative to the bottom surface within the housing. This allows for easy enlargement of the gap between the thermally actuated element and the movable piece on the rear side of the movable piece without hindering the miniaturization of the circuit breaker. Therefore, during the temperature rise of the thermally actuated element, the contact between the thermally actuated element and the movable piece is delayed. Consequently, the thermally actuated element can deform rapidly without being affected by the elasticity of the movable piece, and the operating temperature of the circuit breaker remains stable. Attached Figure Description

[0016] Figure 1 This is a perspective view showing the state of the circuit breaker manufactured by the present invention before assembly. Figure 2This is a cross-sectional view of the circuit breaker under normal charging or discharging conditions. Figure 3 This is a cross-sectional view of the circuit breaker described above, indicating an overcharged state or an abnormal condition. Figure 4 It is Figures 1 to 3 An enlarged cross-sectional view of a circuit breaker. Figure 5 It means Figures 1 to 3 A three-dimensional diagram of the structure of the fixing pieces. Figure 6 Is as Figures 1 to 3 A cross-sectional view of a modified circuit breaker. Figure 7 Is as Figures 1 to 3 A cross-sectional view of another variation of the circuit breaker. Figure 8 Is as Figures 1 to 3 A cross-sectional view of another variation of the circuit breaker. Figure 9 This is a top view showing the configuration of the secondary battery pack equipped with the circuit breaker described above according to the present invention. Figure 10 This is a circuit diagram of the safety circuit of the circuit breaker described above according to the present invention. Detailed Implementation

[0017] A method for manufacturing a circuit breaker according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figures 1 to 3 The configuration of the circuit breaker 1 manufactured by the present invention is shown. The circuit breaker 1 is installed in electrical equipment and the like to protect the electrical equipment from damage caused by excessive temperature rise or overcurrent.

[0018] The circuit breaker 1 comprises a fixed plate 2 with a fixed contact 21, a movable plate 4 with a movable contact 41 at one end, a thermally actuating element 5 that deforms with temperature changes, a PTC (Positive Temperature Coefficient) thermistor 6, and a housing 10 that houses the fixed plate 2, the movable plate 4, the thermally actuating element 5, and the PTC thermistor 6. The housing 10 comprises a housing body (first housing) 7 and a cover member (second housing) 8 mounted on the upper surface of the housing body 7.

[0019] The fixing plate 2 is formed, for example, by pressing a metal plate with copper or similar main components (or a metal plate made of copper-titanium alloy, copper-nickel-zinc alloy, brass, etc.) and is embedded in the housing body 7 by injection molding. A terminal 22 for electrical connection to an external circuit is formed at one end of the fixing plate 2, and a support portion 23 for supporting the PTC thermistor 6 is formed at the other end. The PTC thermistor 6 is placed on and supported by three protrusions 24 formed at the support portion 23 of the fixing plate 2. The fixing plate 2 is bent into a stepped shape, thereby arranging the fixing contact 21 and the support portion 23 with a height difference, easily ensuring space for storing the PTC thermistor 6.

[0020] In addition to silver, nickel, and nickel-silver alloys, the fixed contact 21 is clad with a copper-silver alloy, gold-silver alloy, or other materials with good conductivity. This cladding is formed by plating or coating at a position opposite the movable contact 41, and protrudes from a portion of the opening 73a formed inside the housing body 7. The terminal 22 extends outward from the end edge of the housing body 7. The support portion 23 protrudes from the opening 73d formed inside the housing body 7.

[0021] In this invention, unless otherwise stated, the side of the fixing piece 2 where the fixing contact 21 is formed (i.e., on) Figure 1 The top surface (the side facing upwards) is described as the top surface, and the opposite side is described as the bottom surface. The same applies to other components, such as terminal piece 3, movable piece 4, thermal actuator 5, PTC thermistor 6, and housing 10.

[0022] Terminal piece 3, like fixed piece 2, is formed of a metal plate mainly composed of copper or the like. A terminal 32, electrically connected to an external circuit, is formed at one end of terminal piece 3, and a connecting portion 33, electrically connected to movable piece 4, is formed at the other end. Terminal 32 extends outward from the end edge of housing body 7. Connecting portion 33 is electrically connected to movable piece 4.

[0023] The movable piece 4 is formed into an arm shape that is symmetrical about the center line with respect to the long side by pressing a plate-shaped metal material mainly composed of copper.

[0024] A movable contact 41 is formed at one end of the movable piece 4 along its long side. The movable contact 41 is formed, for example, of the same material as the fixed contact 21, and is joined to one end of the movable piece 4 by means of cladding, crimping, etc., in addition to welding.

[0025] At the other end of the movable piece 4, a connecting portion 42 is formed that is electrically connected to the connecting portion 33 of the terminal piece 3. The top surface of the connecting portion 33 of the terminal piece 3 and the bottom surface of the connecting portion 42 of the movable piece 4 are fixed together, for example, by welding. The bottom surface of the connecting portion 33 contacts the housing body 7, and the top surface of the connecting portion 42 contacts the cover member 8. Thus, the movable piece 4 and the terminal piece 3 are fixed by being sandwiched between the housing body 7 and the cover member 8.

[0026] The movable piece 4 has an elastic portion 43 between the movable contact 41 and the connecting portion 42. The elastic portion 43 extends from the connecting portion 42 toward the movable contact 41. The movable piece 4 is cantilevered by the housing 10 and the terminal piece 3 at the connecting portion 42 on the base end side of the elastic portion 43. In this state, the elastic portion 43 elastically deforms, thereby pressing the movable contact 41 formed at the front end of the elastic portion 43 toward the fixed contact 21 and making contact with it, thereby energizing the fixed piece 2 and the movable piece 4. Since the movable piece 4 is electrically connected to the terminal piece 3, the fixed piece 2 and the terminal piece 3 are energized.

[0027] The movable piece 4 is preferably bent or flexed in the elastic portion 43 by pressing. The degree of bending or flexing is not particularly limited as long as it can accommodate the thermal actuator 5; it can be appropriately set considering the elasticity at operating temperature and recovery temperature, the pressing force of the contact points, etc. Furthermore, a pair of protrusions (contact portions) 44a and 44b are formed on the bottom surface of the elastic portion 43, opposite to the thermal actuator 5. The protrusions 44a and 44b contact the thermal actuator 5, and the deformation of the thermal actuator 5 is transmitted to the elastic portion 43 (see reference 44a and 44b). Figure 1 , Figure 2 as well as Figure 3 ).

[0028] A thermal actuator 5 is disposed between the movable piece 4 and the PTC thermistor 6. Specifically, the thermal actuator 5 is mounted on the top surface 61 of the PTC thermistor 6, which will be described later. The thermal actuator 5 causes the movable piece 4 to transition from a conductive state (where the movable contact 41 is in contact with the fixed contact 21) to a disconnected state (where the movable contact 41 is separated from the fixed contact 21). The thermal actuator 5 is formed into a plate shape by stacking thin plates with different coefficients of thermal expansion, with an initial shape of a curved arc cross-section. If the temperature reaches the reverse operation temperature due to overheating, the curved shape of the thermal actuator 5 warps in the opposite direction with rapid movement; if it cools below the forward recovery temperature, it returns to its original shape. The initial shape of the thermal actuator 5 can be formed by pressing. As long as the elastic portion 43 of the movable piece 4 is lifted up based on the reverse warping deformation of the thermal actuator 5 at the desired temperature and is restored based on the elastic force of the elastic portion 43, the material and shape of the thermal actuator 5 are not particularly limited. However, from the viewpoint of productivity and the efficiency of reverse warping deformation, a rectangular shape is preferred.

[0029] As the material for the thermal actuator 5, a combination of two materials with different coefficients of thermal expansion, composed of various alloys such as copper-nickel-zinc alloy, brass, and stainless steel, is used according to desired conditions. For example, as the material for the thermal actuator 5 to obtain stable reverse operation temperature and forward recovery temperature, a material combining a copper-nickel-manganese alloy on the high expansion side and an iron-nickel alloy on the low expansion side is preferred. Furthermore, from the viewpoint of chemical stability, a material combining an iron-nickel-chromium alloy on the high expansion side and an iron-nickel alloy on the low expansion side is even more preferred. Moreover, from the viewpoint of chemical stability and processability, a material combining an iron-nickel-chromium alloy on the high expansion side and an iron-nickel-cobalt alloy on the low expansion side is even more preferred.

[0030] When the movable piece 4 is in the open state, the PTC thermistor 6 connects the fixed piece 2 and the movable piece 4 via the thermal actuation element 5. The PTC thermistor 6 is disposed between the fixed piece 2 and the thermal actuation element 5. That is, the support portion 23 of the fixed piece 2 is located directly below the thermal actuation element 5 to clamp the PTC thermistor 6. When the energization between the fixed piece 2 and the movable piece 4 is disconnected due to the reverse warping deformation of the thermal actuation element 5, the current flowing in the PTC thermistor 6 increases. The PTC thermistor 6 can be selected according to the needs of operating current, operating voltage, operating temperature, recovery temperature, etc., as long as these characteristics are not impaired, and its material and shape are not particularly limited. In this embodiment, a ceramic sintered body containing barium titanate, strontium titanate, or calcium titanate is used. In addition to ceramic sintered bodies, so-called polymer PTCs containing conductive particles such as carbon can also be used.

[0031] The shell body 7 and the cover component 8 constituting the shell 10 are molded from thermoplastic resins such as flame-retardant polyamide, polyphenylene sulfide (PPS) with excellent heat resistance, liquid crystal polymer (LCP), and polybutylene terephthalate (PBT). If properties equivalent to or better than those of the above resins can be obtained, materials other than resins can also be used.

[0032] The housing body 7 has a top surface 71 and a bottom surface 72. A cover member 8 is mounted on the top surface 71. The bottom surface 72 is located on the opposite side of the top surface 71. The bottom surface 72 is substantially planar. The circuit breaker 1 is usually configured with the bottom surface 72 facing downwards when connected to the connecting wires, but depending on the installation configuration of the secondary battery, etc., the bottom surface 72 may also be configured to face upwards or to the side.

[0033] On the top surface 71 side of the housing body 7, an internal space, namely a recess 73, is formed to accommodate the movable piece 4, the thermal actuator 5, and the PTC thermistor 6. The recess 73 has openings 73a and 73b for accommodating the movable piece 4, an opening 73c for accommodating the movable piece 4 and the thermal actuator 5, and an opening 73d for accommodating the PTC thermistor 6. Furthermore, the end edges of the movable piece 4 and the thermal actuator 5 embedded in the housing body 7 are respectively abutted by the frame forming the recess 73 and guided when the thermal actuator 5 warps and deforms in the opposite direction.

[0034] The cover member 8 is configured to cover the recess 73. The cover member 8 may be in a form that covers at least a portion of the recess 73. A cover plate 81, made primarily of copper or stainless steel, may be injection molded and embedded in the cover member 8. The cover plate 81 not only appropriately abuts against the top surface of the movable piece 4 to restrict the movement of the movable piece 4, but also contributes to the miniaturization of the circuit breaker 1 while improving the rigidity and strength of the cover member 8 and even the housing 10 as a frame.

[0035] In this circuit breaker 1, the movable piece 4 and the terminal piece 3 are integrated by welding or the like to form a composite piece 9. The terminal piece 3 is integrated with the movable piece 4 before being disposed within the housing body 7 to form the composite piece 9. The composite piece 9 is housed within the housing body 7 after the PTC thermistor 6 and the thermal actuator 5 are sequentially housed therein. The composite piece 9 is disposed within the housing body 7 through openings 73a, 73b, and 73c formed in the housing body 7 and is housed in a recess 73. The composite piece 9 can be disposed within the housing body 7 in the same manner as the movable piece disclosed in, for example, WO2011 / 105175.

[0036] like Figure 1 As shown, the cover member 8 is assembled to the housing body 7 to close the openings 73a, 73b, 73c of the housing body 7, which houses the fixing piece 2, terminal piece 3, movable piece 4, thermal actuator 5, and PTC thermistor 6, etc. The housing body 7 and the cover member 8 are joined, for example, by ultrasonic welding.

[0037] Figure 2 as well as Figure 3 The operation of circuit breaker 1 is shown in general. Figure 2 The operation of the circuit breaker 1 under normal charging or discharging conditions is shown. Under normal charging or discharging conditions, the thermally actuated element 5 maintains its initial shape before reverse warping. The elastic part 43 presses the movable contact 41 toward the fixed contact 21, thereby bringing the movable contact 41 into contact with the fixed contact 21, and the fixed plate 2 and terminal plate 3 of the circuit breaker 1 become conductive via the elastic part 43 of the movable plate 4.

[0038] exist Figure 2In the conductive state shown, the thermally actuated element 5 separates from the protrusions 44a and 44b of the movable piece 4 in the conductive state. As a result, the contact pressure between the movable contact 41 and the fixed contact 21 is increased, and the contact resistance between them is reduced.

[0039] The elastic portion 43 of the movable piece 4 can contact the thermally actuated element 5. In this case, the terminal piece 3, movable piece 4, thermally actuated element 5, PTC thermistor 6, and fixed piece 2 are connected as a circuit. However, the resistance of the PTC thermistor 6 is overwhelmingly greater than the resistance of the movable piece 4, so the current flowing in the PTC thermistor 6 is substantially negligible compared to the amount flowing in the fixed contact 21 and the movable contact 41.

[0040] Figure 3 The operation of circuit breaker 1 in case of overcharging or abnormal conditions is shown. The thermally actuated element 5, constructed from stacked thin sheets with different coefficients of thermal expansion, deforms as the temperature rises to correct the deformation. Figure 2 The initial curved shape is shown. Then, the thermally actuated element 5 reaches the operating temperature as shown. Figure 3 As shown, it quickly deforms into a reverse warped shape. This causes the thermal actuator 5 to contact the elastic portion 43 of the movable piece 4, which is then lifted by the thermal actuator 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 interrupted. On the other hand, with the thermal actuator 5 in contact with the movable piece 4, a small amount of leakage current flows through both the thermal actuator 5 and the PTC thermistor 6. That is, the PTC thermistor 6 conducts between the fixed piece 2 and the movable piece 4 via the thermal actuator 5, which moves the movable piece 4 to the off state. As long as this leakage current flows, the PTC thermistor 6 continues to heat up, causing a surge in resistance while maintaining the reverse warped state of the thermal actuator 5. Therefore, the current does not flow along the path between the fixed contact 21 and the movable contact 41, and only the aforementioned small amount of leakage current exists (forming a self-holding circuit). This leakage current can be used for other functions of the safety device.

[0041] If the overcharge state is released or the abnormal state is eliminated, the heating of the PTC thermistor 6 also subsides, and the thermal actuator 5 returns to its forward recovery temperature, restoring its original initial shape. Then, based on the elastic force of the elastic part 43 of the movable piece 4, the movable contact 41 contacts the fixed contact 21 again, the circuit is released from the disconnected state, and returns to normal. Figure 2 The indicated conduction state.

[0042] Figure 4 Will Figure 2 The circuit breaker 1 is shown in enlarged form. With the movable contact 41 as the front side and the connection part 42 as the rear side in the long side direction of the movable piece 4, the PTC thermistor 6 is housed in the housing 10 in a backward tilted position relative to the bottom surface 72.

[0043] Here, the PTC thermistor 6 is housed in the housing 10 in a tilted position relative to the bottom surface 72, such that the distance D from the bottom surface 72 to the center line 6C in the thickness direction of the PTC thermistor 6 decreases from the side of the movable contact 41 of the movable piece 4 towards the side of the connection portion 42.

[0044] As mentioned above, the thermally actuated element 5, which initially protrudes towards the movable piece 4, gradually deforms as the temperature rises. Moreover, in order to enable the thermally actuated element 5 to deform rapidly at a high-precision set operating temperature, it is preferable to maintain the gap S between the thermally actuated element 5 and the movable piece 4 (in this embodiment, the distance between the protrusion 44a and the thermally actuated element 5) so that it is not affected by the elasticity of the movable piece 4 even just before the operating temperature is reached.

[0045] In this circuit breaker 1, the PTC thermistor 6 is tilted backward relative to the bottom surface 72, thereby facilitating the increase of the gap S between the thermally actuated element 5 and the movable plate 4 on the rear side of the movable plate 4 without hindering the miniaturization of the circuit breaker 1. Therefore, as the temperature of the thermally actuated element 5 rises, the contact between the thermally actuated element 5 and the movable plate 4 is delayed. This allows the thermally actuated element 5 to deform rapidly without being affected by the elasticity of the movable plate 4, thus stabilizing the operating temperature of the circuit breaker 1.

[0046] Figure 5 This is a perspective view showing the configuration of the fixing piece 2. The fixing piece 2 includes a first protrusion 24a and a second protrusion 24b, which protrude from the support portion 23 toward the PTC thermistor 6. A pair of first protrusions 24a are provided, and both are disposed on the side of the fixing contact 21 (front side). The second protrusion 24b is disposed on the side of the terminal connection portion 33 (rear side).

[0047] like Figure 4 As shown, the top surface 61 and bottom surface 62 of the main body 60 of the PTC thermistor 6 are substantially planar. The top surface 61 and bottom surface 62 are preferably formed parallel to each other. In this embodiment, a flange 63 is formed on the outer side of the main body 60 of the PTC thermistor 6. The flange 63 may also be omitted. In this case, the main body 60 constitutes a cylindrical PTC thermistor 6.

[0048] The bottom surface 62 of the PTC thermistor 6 abuts against the tops of the pair of first protrusions 24a and second protrusions 24b of the fixing plate 2. That is, the PTC thermistor 6 is supported at three points by the pair of first protrusions 24a and second protrusions 24b. The tops of the pair of first protrusions 24a and second protrusions 24b constitute a support surface 25 for supporting the PTC thermistor 6.

[0049] The protrusion 24 can be composed of a first protrusion 24a and a pair of second protrusions 24b. In this configuration (not shown), the PTC thermistor 6 is supported at three points by the first protrusion 24a and the pair of second protrusions 24b. The tops of the first protrusion 24a and the pair of second protrusions 24b respectively form a support surface 25 for supporting the PTC thermistor 6.

[0050] The protrusion height H1 of the first protrusion 24a is greater than the protrusion height H2 of the second protrusion 24b. Therefore, the support surface 25 is arranged in a backward-tilted position relative to the bottom surface 72. Furthermore, the PTC thermistor 6 supported by the support surface 25 is also arranged in a backward-tilted position relative to the bottom surface 72. Thus, without hindering the miniaturization of the circuit breaker 1, the gap S between the thermally actuated element 5 on the rear side of the movable piece 4 and the movable piece 4 can be easily increased, and the operating temperature of the circuit breaker 1 can be stabilized.

[0051] Figure 6 Is as Figure 4 A cross-sectional view of a modified example of circuit breaker 1, circuit breaker 1A. The above-described configuration of circuit breaker 1 can be used for the following parts of circuit breaker 1A that are not described.

[0052] In circuit breaker 1A, the second protrusion 24b of the fixing piece 2A is removed. Therefore, the support portion 23 abuts against the bottom surface 62 of the PTC thermistor 6 at the contact point 26 where the pair of first protrusions 24a and the rear end of the bottom surface 62 meet. Thus, the bottom surface 62 of the PTC thermistor 6 is supported at three points by the pair of first protrusions 24a and the contact point 26 abutting against the fixing piece 2. The tops of each of the pair of first protrusions 24a and the contact point 26 constitute a support surface 25A for supporting the PTC thermistor 6.

[0053] The fixing piece 2A of circuit breaker 1A has been removed. Figure 4 , 5 As shown in the diagram, the second protrusion 24b allows the support surface 25A to be arranged in a backward-leaning position relative to the bottom surface 72. Furthermore, the PTC thermistor 6 supported by the support surface 25A is also arranged in a backward-leaning position relative to the bottom surface 72. Therefore, without hindering the miniaturization of the circuit breaker 1A, the gap S between the thermally actuated element 5 on the rear side of the movable piece 4 and the movable piece 4 can be easily increased, and the operating temperature of the circuit breaker 1A can be stabilized.

[0054] The fixing piece 2A of circuit breaker 1A has been removed. Figure 4 , 5 The second protrusion 24b shown allows the PTC thermistor 6 to be mounted lower relative to the bottom surface 72 by setting the protrusion height H1 of the first protrusion 24a lower relative to the fixing piece 2. Therefore, miniaturization of the circuit breaker 1A becomes even easier.

[0055] Figure 7 Is as Figure 4 A cross-sectional view of circuit breaker 1B, another variation of circuit breaker 1. The above-described configuration of circuit breaker 1, etc., can be used for the following undescribed parts of circuit breaker 1B.

[0056] In circuit breaker 1B, the fixing piece 2B is embedded in the housing 10 in a rearward-leaning position relative to the bottom surface 72 by the support portion 23B. This configuration can be easily achieved, for example, by supporting the fixing piece 2B in a rearward-leaning position relative to the mold during the forming of the housing body 7.

[0057] In circuit breaker 1B, the top surface of the support portion 23B opposite to the PTC thermistor 6 forms a support surface 25B. That is, the support portion 23B contains a support surface 25B.

[0058] The fixed plate 2B is embedded in the housing 10 with its support surface 25B tilted backward relative to the bottom surface 72. Consequently, the PTC thermistor 6, supported by the support portion 23B on the support surface 25B, is also positioned with its support surface 72 tilted backward. Therefore, without hindering the miniaturization of the circuit breaker 1B, the gap S between the thermally actuated element 5 and the movable plate 4 on the rear side of the movable plate 4 can be easily increased, and the operating temperature of the circuit breaker 1B remains stable.

[0059] Figure 8 Is as Figure 4 A cross-sectional view of circuit breaker 1C, another variation of circuit breaker 1. The above-described configuration of circuit breaker 1, etc., can be used for the following parts of circuit breaker 1C that are not described.

[0060] In the fixing piece 2C of the circuit breaker 1C, the thickness of the support portion 23C is formed to decrease towards the rear. The overall thickness of the fixing piece 2B can also be configured to decrease towards the rear. Such a fixing piece 2C is easy to form through pressing or other processes.

[0061] The top surface of the support portion 23C, which is opposite to the PTC thermistor 6, forms the support surface 25C. That is, the support portion 23B contains the support surface 25B.

[0062] In the fixed plate 2C, the thickness of the support portion 23C decreases towards the rear, thus the support surface 25B can easily tilt backward relative to the bottom surface 72. Consequently, the PTC thermistor 6 supported by the support surface 25B is also arranged in a backward tilted position relative to the bottom surface 72. Therefore, without hindering the miniaturization of the circuit breaker 1C, the gap S between the thermally actuated element 5 and the movable plate 4 on the rear side of the movable plate 4 can be easily increased, and the operating temperature of the circuit breaker 1C is stabilized.

[0063] Although the first protrusion 24a and the second protrusion 24b are omitted in circuit breakers 1B and 1C, protrusions equivalent to those in existing circuit breakers can also be formed in the support portion 23 of the fixing piece 2. Alternatively, similar to circuit breaker 1, a second protrusion 24b with a smaller protrusion height than the first protrusion 24a can be formed. Furthermore, similar to circuit breaker 1A, only the first protrusion 24a can be formed.

[0064] Although the circuit breaker 1 and the like of the present invention have been described in detail above, the present invention is not limited to the specific embodiments described above and can be implemented in various forms. That is, the circuit breaker 1 and the like of the present invention can be implemented as long as it meets the following configuration, namely, it includes at least: a fixed piece 2 having a fixed contact 21; a movable piece 4 having a movable contact 41, which is pressed against and contacts the fixed contact 21; a thermally actuated element 5 that deforms with temperature changes, thereby transferring the movable piece 4 from a conducting state where the movable contact 41 contacts the fixed contact 21 to a disconnected state where the movable contact 41 separates from the fixed contact 21; and a PTC thermistor 6. When the movable piece 4 is in the open state, it makes the fixed piece 2 and the movable piece 4 conduct; and the housing 10, which houses the fixed piece 2, the movable piece 4, the thermal actuator 5 and the PTC thermistor 6, the thermal actuator 5 being disposed between the movable piece 4 and the PTC thermistor 6, the housing 10 having a bottom surface 72, and when the side with the movable contact 41 in the long side direction of the movable piece 4 is taken as the front side, the PTC thermistor 6 is housed in the housing 10 in a backward tilted position relative to the bottom surface 72.

[0065] Therefore, in the circuit breaker 1 of the present invention, the movable piece 4 and the terminal piece 3 can be integrally formed by pressing.

[0066] In addition, the circuit breaker 1 of the present invention can also be widely applied to secondary battery packs, safety circuits for electrical equipment, etc. Figure 9 A secondary battery pack 500 is shown. The secondary battery pack 500 includes a secondary battery 501 and a circuit breaker 1 provided in the output circuit of the secondary battery 501. Figure 10 A safety circuit 502 for electrical equipment is shown. The safety circuit 502 includes a circuit breaker 1 connected in series in the output circuit of the secondary battery 501. Based on the secondary battery pack 500 or the safety circuit 502 including the circuit breaker 1, it is possible to manufacture a secondary battery pack 500 or the safety circuit 502 that can be easily miniaturized while maintaining resistance during conduction. (Label Explanation)

[0067] 1 circuit breaker 1A circuit breaker 1B circuit breaker 1C circuit breaker 2 fixing plates 2A fixing plate 2B fixing plate 2C fixing plate 4 movable pieces 5 thermal actuators 6PTC thermistor (positive characteristic thermistor) 10 housing 21 fixed contacts 23 Support section 23B Support 23C support section 24 protrusions 24a First protrusion 24b Second protrusion 25 support surface 25A support surface 25B support surface 25C support surface 41 movable contacts 44a protrusion 44b protrusion 62 bottom 72 bottom 500 secondary battery pack 502 Safety Circuit H1 protrusion height H2 highlights the height.

Claims

1. A circuit breaker, comprising: A fixing plate, which has fixing contacts; A movable piece having a movable contact, wherein the movable contact is pressed against the fixed contact to make the movable contact contact with the fixed contact; A thermally actuated element that deforms with temperature changes, thereby causing the movable piece to shift from a conductive state where the movable contact is in contact with the fixed contact to a disconnected state where the movable contact is separated from the fixed contact. A positive characteristic thermistor, when the movable piece is in the open state, causes the fixed piece and the movable piece to conduct; as well as The housing accommodates the fixed plate, the movable plate, the thermally actuated element, and the positive characteristic thermistor. The thermally actuated element is disposed between the movable piece and the positive characteristic thermistor. The shell has a bottom surface. When the side with the movable contact is taken as the front side along the long side of the movable piece, The positive characteristic thermistor is housed in the housing in a tilted-back position relative to the bottom surface of the housing.

2. The circuit breaker according to claim 1, wherein, The fixing plate has a supporting surface that abuts against the bottom surface of the positive characteristic thermistor and is used to support the positive characteristic thermistor. The support surface is configured in a backward tilted position relative to the bottom surface of the housing.

3. The circuit breaker according to claim 2, wherein, The support surface includes a first protrusion that extends toward the side of the positive characteristic thermistor.

4. The circuit breaker according to claim 3, wherein, The support surface includes a second protrusion at a position rearward of the first protrusion, protruding toward the side of the positive characteristic thermistor, wherein the protrusion height of the first protrusion is greater than the protrusion height of the second protrusion.

5. The circuit breaker according to any one of claims 2 to 4, wherein, The fixed piece has a support portion, which includes the support surface and extends along the long side of the movable piece. The fixing piece is embedded in the housing in a rearward tilted position relative to the bottom surface of the housing.

6. The circuit breaker according to any one of claims 2 to 4, wherein, The fixed piece has a support portion, which includes the support surface and extends along the long side of the movable piece. The thickness of the support portion decreases towards the rear.

7. A safety circuit for electrical equipment, comprising the circuit breaker according to any one of claims 1 to 6.

8. A secondary battery pack comprising the circuit breaker according to any one of claims 1 to 6.

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