Circuit breakers, safety circuits, and secondary battery packs

Abstract

The circuit breaker (1) comprises: a first terminal piece (2) having a fixed contact (21); a movable piece (4) having a movable contact (41) for pressing the movable contact (41) against the fixed contact (21) to make them contact; a thermally responsive element (5) that deforms with temperature changes, thereby actuating the movable piece (4) to separate the movable contact (41) from the fixed contact (21); and a second terminal piece (3) electrically connected to the movable piece (4). The movable contact (41) includes a first movable contact (41a) disposed at a first end (40a) in the longitudinal direction of the movable piece (4) and a second movable contact (41b) disposed at a second end (40b) in the longitudinal direction of the movable piece (4). The fixed contact (21) includes a first fixed contact (21a) disposed at a position accessible by the first movable contact (41a) and a second fixed contact (21b) disposed at a position accessible by the second movable contact (41b).

Description

TECHNICAL FIELD

[0001] The present application relates to a circuit breaker or the like for a safety circuit of an electrical apparatus. BACKGROUND

[0002] Conventionally, a circuit breaker each having a pair of fixed contacts and movable contacts has been disclosed (for example, refer to Patent Document 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENT

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-331705 SUMMARY

[0006] (PROBLEMS TO BE SOLVED BY THE INVENTION)

[0007] In the circuit breaker shown in the above Patent Document 1, the pair of contacts are connected in series. Therefore, it is difficult to reduce the resistance between the terminals.

[0008] The present application has been made in view of the above actual circumstances, and it is a main object thereof to provide a circuit breaker capable of reducing the resistance between terminals.

[0009] (Technical Solution for Solving the Problems)

[0010] The present application is a circuit breaker including a first terminal piece formed with a fixed contact, a movable piece having a movable contact and configured to make the movable contact contact the fixed contact by pressing the movable contact to the fixed contact, a thermal responsive element configured to deform with a change in temperature, thereby causing the movable piece to act in such a manner that the movable contact is separated from the fixed contact, and a second terminal piece electrically connected to the movable piece, the movable contact including a first movable contact disposed at a first end portion in a longitudinal direction of the movable piece and a second movable contact disposed at a second end portion in the longitudinal direction of the movable piece, and the fixed contact including a first fixed contact disposed at a position where the first movable contact can contact and a second fixed contact disposed at a position where the second movable contact can contact.

[0011] In the circuit breaker according to the present application, preferably, the movable piece has a first contact region contacting the second terminal piece between the first movable contact and the second movable contact.

[0012] In the circuit breaker according to the present application, preferably, the natural vibration frequency of the movable piece is different between a first portion from the first contact region to the side of the first end portion and a second portion from the first contact region to the side of the second end portion.

[0013] In the circuit breaker according to the present application, preferably, the heat responsive element has a top portion protruding toward the movable piece side, and the first contact region is provided in an area overlapping the top portion, as viewed in a thickness direction of the movable piece.

[0014] In the circuit breaker according to the present application, preferably, the movable piece has a first bent portion bent so that the first movable contact approaches the first fixed contact.

[0015] In the circuit breaker according to the present application, preferably, the movable piece has a first protrusion protruding toward the heat responsive element side between the first movable contact and the first bent portion.

[0016] In the circuit breaker according to the present application, preferably, the second terminal piece has a second contact region contacting the first contact region, and has a first protruding portion protruding toward the movable piece side between the first protrusion and the second contact region.

[0017] The present application is a safety circuit for an electrical device provided with the circuit breaker.

[0018] The present application is a secondary battery pack provided with the circuit breaker.

[0019] (EFFECT OF INVENTION)

[0020] In the circuit breaker according to the present application, the first fixed contact and the second fixed contact are provided in the first terminal piece, and the movable piece is electrically connected to the second terminal piece. When the first movable contact of the movable piece contacts the first fixed contact and the second movable contact of the movable piece contacts the second fixed contact, a parallel circuit is formed between the first terminal piece and the second terminal piece. Thus, the resistance between the first terminal piece and the second terminal piece is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a perspective view before assembly showing the schematic structure of the circuit breaker according to an embodiment of the present application.

[0022] Figure 2 is a sectional view showing the above-described circuit breaker in a normal charging or discharging state.

[0023] Figure 3 is a sectional view showing the above-described circuit breaker in an overcharge state or an abnormal state, etc.

[0024] Figure 4 is a sectional view showing the path of the current flow in the circuit breaker in a current application state.

[0025] Figure 5 is a sectional view showing the connection portion of the second terminal piece, the first contact region of the movable piece, and the periphery thereof, enlarged.

[0026] Figure 6 is a perspective view showing the circuit breaker of Figure 1 before assembly.

[0027] Figure 7 is a perspective view showing another modification of the circuit breaker of Figure 1 before assembly.

[0028] Figure 8 is a plan view showing the structure of a secondary battery pack equipped with the above-described circuit breaker of the present application.

[0029] Figure 9 is a circuit diagram of a safety circuit equipped with the above-described circuit breaker of the present application. DETAILED DESCRIPTION

[0030] A circuit breaker of one embodiment of the present application will be described with reference to the drawings. Figures 1 to 3 The structure of a circuit breaker 1 is shown. As shown in Figure 1 and Figure 3 , the circuit breaker 1 is equipped with a first terminal piece 2, a second terminal piece 3, a movable piece 4, a thermal response element 5, a PTC (Positive Temperature) thermistor 6, and the like. The circuit breaker 1 constitutes a main part of a safety circuit of an electrical device by being connected to an external circuit through the first terminal piece 2 and the second terminal piece 3.

[0031] The first terminal piece 2, the second terminal piece 3, the movable piece 4, the thermal response element 5, and the PTC thermistor 6 are housed in a housing 10. The housing 10 is constituted of a housing main body (first housing) 7 and a cover member (second housing) 8 mounted to the upper surface of the housing main body 7, and the like.

[0032] The first terminal piece 2 is formed in a plate shape by, for example, press working a metal plate having copper or the like as a main component (in addition to this, a copper-titanium alloy, copper-zinc, brass, or the like). The first terminal piece 2 has a long side direction. The first terminal piece 2 is embedded in the housing main body 7 by insert molding.

[0033] The first terminal piece 2 has a pair of fixed contacts 21 and a first terminal 22. The second terminal piece 3 has a second terminal 32. The second terminal piece 3 is electrically connected to the movable piece 4. The movable piece 4 has a pair of movable contacts 41, and the movable contacts 41 are pressed against the fixed contacts 21 so as to be in contact. The thermal response element 5 deforms in accordance with a change in temperature, thereby causing the movable piece 4 to act so that the movable contacts 41 are separated from the fixed contacts 21.

[0034] The fixed contact 21 includes a first fixed contact 21a and a second fixed contact 21b. The first fixed contact 21a and the second fixed contact 21b are formed by plating or coating, etc. of a material having good electrical conductivity such as a copper-silver alloy, a gold-silver alloy, etc. in addition to silver, nickel, a nickel-silver alloy, etc.

[0035] The first fixed contact 21a and the second fixed contact 21b are formed on the same face of the first terminal piece 2. In the present application, with respect to the first terminal piece 2, the face on which the fixed contact 21 is formed (i.e. the face on the upper side in FIG. 1) is referred to as an A face, and the bottom face on the opposite side thereof is referred to as a B face. The same applies to other components such as the second terminal piece 3, the movable piece 4, the heat-responsive element 5, the case 10, etc. Figure 1 The first fixed contact 21a is formed on one end portion of the first terminal piece 2. The first fixed contact 21a is exposed to the accommodation recess 73 of the case main body 7 via a portion of the opening 73a formed in the interior of the case main body 7.

[0036] The first terminal 22 is formed on the other end portion of the first terminal piece 2. The first terminal 22 protrudes from the side wall of the case main body 7 and is connected to an external circuit.

[0037] The second fixed contact 21b is formed in the vicinity of the first terminal 22, i.e. on the other side of the first terminal piece 2. The second fixed contact 21b is exposed to the accommodation recess 73 of the case main body 7 via a portion of the opening 73b formed in the interior of the case main body 7.

[0038] A support portion 23 that supports the PTC thermistor 6 is formed between the first fixed contact 21a and the second fixed contact 21b. The support portion 23 is exposed to the accommodation recess 73 of the case main body 7 via a portion of the opening 73d formed in the interior of the case main body 7 and is electrically connected to the PTC thermistor 6.

[0039] As shown in FIG. 1, the first terminal piece 2 has a first step bent portion 25a and a second step bent portion 25b that are bent in a stepped manner (in a crank shape in side view). The first step bent portion 25a connects the first fixed contact 21a and the support portion 23 and arranges the first fixed contact 21a and the support portion 23 to be different in height. The second step bent portion 25b connects the second fixed contact 21b and the support portion 23 and arranges the second fixed contact 21b and the support portion 23 to be different in height. Thus, the PTC thermistor 6 can be accommodated compactly.

[0040] Figure 2

[0041] ​​The second terminal piece 3 is formed in a plate shape by press working a metal plate having copper or the like as a main component, similarly to the first terminal piece 2. The second terminal piece 3 has a long direction. The second terminal piece 3 is embedded in the cover member 8 by insert molding. The second terminal piece 3 is arranged so that the long direction of the second terminal piece 3 is parallel to the long direction of the first terminal piece 2.

[0042] The second terminal piece 3 has a connection portion 31 electrically connected to the movable piece 4 and a second terminal 32 electrically connected to an external circuit. The connection portion 31 is arranged at a position opposite to a first contact region 42 described later.

[0043] The second terminal 32 is formed on one side of the second terminal piece 3 (i.e., the first fixed contact 21a side in the first terminal piece 2). The second terminal 32 protrudes from the side wall of the housing main body 7 and is connected to an external circuit. The second terminal 32 is exposed on the inside of the housing 10 for accommodating the movable piece 4 and the like on the inside of the cover member 8.

[0044] The second terminal piece 3 functions to reinforce the cover member 8. That is, the second terminal piece 3 improves the rigidity and strength of the cover member 8, even the housing 10 as a frame, and contributes to the miniaturization of the circuit breaker 1.

[0045] The movable piece 4 is formed in a plate shape by press working a metal material having copper or the like as a main component. The movable piece 4 has a long direction. The movable piece 4 is formed in an arm shape symmetric to the center line with respect to the long direction.

[0046] A movable contact 41 is formed on both end portions of the movable piece 4. The movable contact 41 is formed on the B face of the movable piece 4 by a material equivalent to the fixed contact 21 and is joined to the movable piece 4 by a method such as cladding, crimping, or the like, other than welding.

[0047] The movable contact 41 includes a first movable contact 41a and a second movable contact 41b. The first movable contact 41a includes a first movable contact 41a arranged on the first end portion 40a in the long direction of the movable piece 4 and a second movable contact 41b arranged on the second end portion 40b in the long direction of the movable piece 4.

[0048] The movable piece 4 is arranged so that the long direction of the movable piece 4 is parallel to the long direction of the first terminal piece 2. Further, the movable piece 4 is arranged so that the first movable contact 41a is positioned at a position capable of contacting the first fixed contact 21a and the second movable contact 41b is positioned at a position capable of contacting the second fixed contact 21b. In other words, the first fixed contact 21a is arranged at a position opposite to the first movable contact 41a and capable of contacting the same, and the second fixed contact 21b is arranged at a position opposite to the second movable contact 41b and capable of contacting the same.

[0049] A first contact region 42 that is electrically connected to the second terminal piece 3 is provided between the first movable contact 41a and the second movable contact 41b. Thus, the second movable contact 41b is disposed on the side opposite the first movable contact 41a with the first contact region 42 interposed therebetween. The second terminal 32 of the second terminal piece 3 is connected to the first movable contact 41a and the second movable contact 41b via the first contact region 42.

[0050] The movable piece 4 has a first elastic portion 43a between the first movable contact 41a and the first contact region 42. The first elastic portion 43a extends from the first contact region 42 toward the first movable contact 41a side. In addition, the movable piece 4 has a second elastic portion 43b between the second movable contact 41b and the first contact region 42. The second elastic portion 43b extends from the first contact region 42 toward the second movable contact 41b side.

[0051] The first contact region 42 is formed to be wider than the first elastic portion 43a and the second elastic portion 43b. Thus, the contact resistance between the connection portion 31 and the first contact region 42 is reduced.

[0052] The thermal response element 5 shifts the state of the movable piece 4 from the on state in which the movable contact 41 is in contact with the fixed contact 21 to the off state in which the movable contact 41 is separated from the fixed contact 21. In the on state, the first movable contact 41a is in contact with the first fixed contact 21a, and the second movable contact 41b is in contact with the second fixed contact 21b.

[0053] The thermal response element 5 has an initial shape in which it is curved in a circular arc shape, and is formed by laminating thin plate materials having different thermal expansion rates. When the operating temperature is reached due to overheating, the curved shape of the thermal response element 5 is reversed by snap action, and returns if it is lowered to below the recovery temperature due to cooling. The initial shape of the thermal response element 5 can be formed by press working. As long as the first elastic portion 43a and the second elastic portion 43b of the movable piece 4 are pushed up by the snap action of the thermal response element 5 at the desired temperature, and return by the elastic force of the first elastic portion 43a and the second elastic portion 43b, the material and shape of the thermal response element 5 are not particularly limited, but from the viewpoint of productivity and efficiency of the snap action, a rectangular shape is preferable, and in order to efficiently push up the first elastic portion 43a and the second elastic portion 43b while being small, a long rectangular shape close to a square shape is preferable. In addition, as the material of the thermal response element 5, for example, a material composed of two materials having different thermal expansion rates, such as copper-nickel-manganese alloy or nickel-chromium-iron alloy on the high expansion side, and iron-nickel alloy and various alloys such as copper-zinc, brass, and stainless steel on the low expansion side, is used in combination according to the required conditions.

[0054] The PTC thermistor 6 is mounted on and supported by the protrusions 24 formed at three points on the support portion 23 of the first terminal piece 2. When the movable piece 4 is in the off state, the PTC thermistor 6 makes the first terminal piece 2, the second terminal piece 3, and the movable piece 4 conductive. The PTC thermistor 6 is disposed between the support portion 23 of the first terminal piece 2 and the thermal response element 5. When the energization between the first terminal piece 2 and the movable piece 4 is cut off by the anti-tilting action of the thermal response element 5, the current flowing through the PTC thermistor 6 increases. The PTC thermistor 6 is a positive characteristic thermistor whose resistance increases with temperature and limits the current. It can be selected according to the needs of operating current, operating voltage, operating temperature, recovery temperature, etc., and its material and shape are not particularly limited as long as they do not impair these characteristics. 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 in polymers can also be used.

[0055] The shell body 7 and cover component 8 constituting the shell 10 are molded from thermoplastic resins such as flame-retardant polyamide, heat-resistant polyphenylene sulfide (PPS), liquid crystal polymer (LCP), and polybutylene terephthalate (PBT). Insulating materials other than resins may also be used, provided that properties equivalent to or better than those of the aforementioned resins can be obtained.

[0056] The housing body 7 has an internal space, namely a receiving recess 73, for accommodating the movable piece 4, the thermal response element 5, and the PTC thermistor 6. The receiving recess 73 has openings 73a and 73b for accommodating the first movable contact 41a and the second movable contact 41b of the movable piece 4, an opening 73c for accommodating the movable piece 4 and the thermal response element 5, and an opening 73d for accommodating the PTC thermistor 6. In addition, the end edge of the thermal response element 5 assembled on the housing body 7 is appropriately abutted by a frame formed inside the receiving recess 73 and is guided when the thermal response element 5 is tilted back.

[0057] like Figure 1 As shown, the cover member 8 is installed on the housing body 7 by blocking the openings 73a, 73b, 73c of the housing body 7, which houses the fixed contact 21, movable piece 4, thermal response element 5, and PTC thermistor 6. The housing body 7 and the cover member 8 are joined, for example, by ultrasonic welding. At this time, the housing body 7 and the cover member 8 are continuously joined along the entire circumference of their respective outer edges, improving the airtightness of the housing 10. As a result, the internal space of the housing 10 formed by the receiving recess 73 is sealed, and components such as the movable piece 4, thermal response element 5, and PTC thermistor 6 are shielded from the ambient gas outside the housing 10, thereby being protected.

[0058] Figure 2This indicates the operation of circuit breaker 1 under normal charging or discharging conditions. Under normal charging or discharging conditions, the thermal response element 5 maintains its initial shape (before tilting back). In this state, the first fixed contact 21a is in contact with the first movable contact 41a, and the second fixed contact 21b is in contact with the second movable contact 41b. Furthermore, the first contact area 42 of the movable piece 4 is electrically connected to the second terminal piece 3, thus conducting electricity between the first terminal piece 2 and the second terminal piece 3 of circuit breaker 1 through the movable piece 4. The movable piece 4 is in contact with the thermal response element 5, and the movable piece 4, the thermal response element 5, the PTC thermistor 6, and the first terminal piece 2 can also function as a conductive circuit.

[0059] Figure 3 This indicates the operation of circuit breaker 1 in case of overcharging or abnormality. If the circuit breaker reaches a high temperature due to overcharging or abnormality, the thermal response element 5, which has reached its operating temperature, will tilt upwards, pushing the first elastic portion 43a of the movable piece 4 upwards, separating the first fixed contact 21a from the first movable contact 41a. Additionally, the second elastic portion 43b of the movable piece 4 will be pushed upwards, separating the second fixed contact 21b from the second movable contact 41b.

[0060] Inside the circuit breaker 1, the thermal response element 5 deforms, and when the movable piece 4 is pushed upward, the operating temperature of the thermal response element 5 is, for example, 70°C to 90°C. At this time, the current flowing between the first fixed contact 21a and the first movable contact 41a, and the current flowing between the second fixed contact 21b and the second movable contact 41b, are interrupted, and a small leakage current flows through the thermal response element 5 and the PTC thermistor 6. The PTC thermistor 6 continues to heat up as long as such leakage current flows, causing the thermal response element 5 to remain in the reverse-tilted state while its resistance value surges. Therefore, the current does not flow through the paths between the first fixed contact 21a and the first movable contact 41a, and between the second fixed contact 21b and the second movable contact 41b; only the aforementioned small leakage current exists (forming a self-holding circuit). This leakage current can be allocated to other functions of the safety device.

[0061] Figure 4 This indicates the path of current flow within the circuit breaker 1 when it is energized. As described above, in the circuit breaker 1, a first fixed contact 21a and a second fixed contact 21b are provided on the first terminal piece 2, and a movable piece 4 is electrically connected to the second terminal piece 3. The movable piece 4 is provided with a first movable contact 41a and a second movable contact 41b.

[0062] If the first movable contact 41a of the movable piece 4 contacts the first fixed contact 21a, a first path I1 is formed from the first terminal piece 2 through the first fixed contact 21a, the first movable contact 41a, the first elastic portion 43a, and the first contact area 42 to the second terminal piece 3. On the other hand, if the second movable contact 41b of the movable piece 4 contacts the second fixed contact 21b, a second path I2 is formed from the first terminal piece 2 through the second fixed contact 21b, the second movable contact 41b, the second elastic portion 43b, and the first contact area 42 to the second terminal piece 3. That is, a parallel circuit is formed between the first terminal piece 2 and the second terminal piece 3.

[0063] Therefore, the cross-sectional area of ​​the conductor between the movable contact 41 and the first contact area 42 is doubled, reducing the conduction resistance. Furthermore, since the fixed contact 21 and the movable contact 41 are in contact at two points, the contact resistance is reduced. Thus, the resistance between the first terminal piece 2 and the second terminal piece 3 is reduced.

[0064] Alternatively, increasing the cross-sectional area of ​​the conductor can be achieved simply by increasing the width and thickness of the movable piece 4. However, increasing the width and thickness of the movable piece 4 increases the elastic force generated by it, requiring an increase in the thickness of the thermal response element 5, making it difficult to miniaturize the circuit breaker 1.

[0065] Furthermore, according to the circuit breaker 1, the fixed contact 21 and the movable contact 41 are in contact at point 2, thereby ensuring the continuity between the first terminal piece 2 and the movable piece 4. Therefore, even when the circuit breaker 1 is subjected to a strong impact due to the falling of electrical equipment on which the circuit breaker 1 is installed, the continuity between the first terminal piece 2 and the movable piece 4 can be easily maintained, suppressing the momentary interruption of the current supplied to the load.

[0066] The first contact area 42 preferably contacts the second terminal piece 3 between the first movable contact 41a and the second movable contact 41b. This allows for easy shortening of the overall length of the circuit breaker 1. Furthermore, the contact resistance between the first contact area 42 and the second terminal piece 3 is easily reduced.

[0067] Preferably, the movable piece 4 is fixed to the second terminal piece 3 in the first contact area 42. As a result, the movable piece 4 has a stable posture, which makes it easier to reduce the contact resistance between the first contact area 42 and the second terminal piece 3.

[0068] The fixing structure of the second terminal piece 3 and the movable piece 4 can be, for example, laser welding or resistance welding, bonding using conductive adhesive, or thread fastening.

[0069] The connecting portion 31 and the first contact area 42 are preferably formed in a planar shape. This facilitates the connection between the connecting portion 31 and the first contact area 42. In particular, the workability of the welding process is improved when the second terminal piece 3 and the movable piece 4 are fixed by welding. Furthermore, the contact area between the connecting portion 31 and the first contact area 42 can be easily ensured.

[0070] The movable piece 4 can also be configured such that the natural vibration frequencies of the first portion 45a from the first contact area 42 to the first end 40a side and the second portion 45b from the second end 40b side are different. By making the natural vibration frequencies of the first portion 45a and the second portion 45b different, even when the circuit breaker 1 is subjected to impacts of various intensities, it is possible to suppress the simultaneous departure of the first movable contact 41a and the second movable contact 41b from the fixed contact 21, thereby suppressing the momentary interruption of the current supplied to the load.

[0071] By adjusting the length, width, and thickness of the first part 45a and the second part 45b, their natural vibration frequencies can be easily achieved. The length of the first part 45a refers to the length of the first part 45a along the long side of the movable piece 4, that is, the distance from the first contact area 42 to the front end of the first end 40a. The width of the first part 45a refers to the length of the first part 45a along the short side, which is orthogonal to the long side of the movable piece 4. The length, width, and thickness of the first part 45a can also be their average values. The same applies to the second part 45b.

[0072] like Figure 1 and Figure 2 As shown, the thermal response element 5 has a top 51 protruding towards the movable piece 4. Viewed from the short side direction of the movable piece 4, the top 51 is the part where the distance between the second terminal piece 3 and the thermal response element 5 is smallest. Viewed from the thickness direction of the movable piece 4, the first contact area 42 is located in the area overlapping with the top 51. Thus, in Figure 3 When the circuit breaker is cut off, the overall length of the circuit breaker 1 can be easily shortened while ensuring the gap between the first movable contact 41a and the first fixed contact 21a and the gap between the second movable contact 41b and the second fixed contact 21b.

[0073] Figure 5 Enlarged view of the connecting portion 31 of the second terminal piece 3, the first contact area 42 of the movable piece 4 and its surrounding area.

[0074] The movable piece 4 preferably has a bent portion 46a between the first contact area 42 and the first elastic portion 43a. The bent portion 46a bends such that the first movable contact 41a approaches the first fixed contact 21a. By providing the bent portion 46a in the movable piece 4, the contact pressure between the first movable contact 41a and the first fixed contact 21a can be increased, and the contact resistance between them can be reduced. In addition, a space is created between the second terminal piece 3 and the first elastic portion 43a for the first elastic portion 43a to deform. Figure 3 When the cut is made as shown, it is easy to ensure the gap between the first movable contact 41a and the first fixed contact 21a.

[0075] Similarly, the movable piece 4 preferably has a bent portion 46b between the first contact area 42 and the second elastic portion 43b. The bent portion 46b bends such that the second movable contact 41b approaches the second fixed contact 21b.

[0076] The movable piece 4 preferably has a bent portion 47a between the bent portion 46a and the first elastic portion 43a. The bent portion 47a bends in the opposite direction to the bent portion 46a, i.e., the first movable contact 41a moves away from the first fixed contact 21a. By providing the bent portions 46a and 47a on the movable piece 4, the contact pressure between the first movable contact 41a and the first fixed contact 21a can be increased, and the thickness of the circuit breaker 1 can be reduced.

[0077] Similarly, the movable piece 4 preferably has a bent portion 47b between the bent portion 46b and the second elastic portion 43b. The bent portion 47b is bent in the opposite direction to the bent portion 46b, that is, in a manner that the second movable contact 41b is separated from the second fixed contact 21b.

[0078] like Figure 2 and Figure 3 As shown, the movable piece 4 preferably has a protrusion 44a protruding toward the thermal response element 5. The protrusion 44a is disposed in the first elastic portion 43a between the first movable contact 41a and the bent portion 46a. The protrusion 44a is preferably disposed near the end edge of the thermal response element 5. By providing the protrusion 44a in the first elastic portion 43a, in Figure 3 When the cut is made as shown, it is easy to ensure the gap between the first movable contact 41a and the first fixed contact 21a.

[0079] Similarly, the movable piece 4 preferably has a protrusion 44b protruding toward the thermal response element 5. The protrusion 44b is disposed in the second elastic portion 43b between the second movable contact 41b and the bent portion 46b. The protrusion 44b is preferably disposed near the end edge of the thermal response element 5. Alternatively, only one of the protrusions 44a and 44b may be provided.

[0080] The second terminal piece 3 preferably has a protrusion 33a protruding toward the movable piece 4. By providing the protrusion 33a on the second terminal piece 3, in Figure 2 When the circuit is activated, the contact pressure between the first movable contact 41a and the first fixed contact 21a increases. A protrusion 33a is disposed between the connecting portion 31 and the protrusion 44a along the long side of the movable piece 4. Furthermore, the connecting portion 31 is the second contact area that contacts the first contact area 42. By distributing the protrusion 33a between the connecting portion 31 and the protrusion 44a, the contact pressure increases. Figure 3 When the cut is made as shown, it is easy to ensure the gap between the first movable contact 41a and the first fixed contact 21a.

[0081] Similarly, the second terminal piece 3 preferably has a protrusion 33b protruding toward the movable piece 4. The protrusion 33b is disposed between the connecting portion 31 and the protrusion 44b in the long side direction of the movable piece 4. Alternatively, only one of the protrusions 33a and 33b may be provided.

[0082] Figure 6 Is as Figure 1 A perspective view of a modified circuit breaker 1A. The structure of the circuit breaker 1 described above can be used for the following undescribed parts of the circuit breaker 1A.

[0083] Circuit breaker 1A includes a first terminal piece 2, a second terminal piece 3, a movable piece 4A, a thermal response element 5, and a PTC thermistor 6. The movable piece 4A differs from other circuit breakers in that it has two pairs of movable contacts 41a1, 41a2, 41b1, 41b2 and two pairs of elastic portions 43a1, 43a2, 43b1, 43b2. Figure 1 The movable piece 4 shown is different.

[0084] That is, in the movable piece 4A, the first movable contact 41a includes movable contact 41a1 and movable contact 41a2, and the first elastic part 43a includes elastic part 43a1 and elastic part 43a2. Movable contact 41a1 is formed in elastic part 43a1, and movable contact 41a2 is formed in elastic part 43a2.

[0085] Similarly, in the movable piece 4A, the second movable contact 41b includes movable contact 41b1 and movable contact 41b2, and the second elastic portion 43b includes elastic portion 43b1 and elastic portion 43b2. Movable contact 41b1 is formed in elastic portion 43b1, and movable contact 41b2 is formed in elastic portion 43b2.

[0086] A slit 48a is formed in the first elastic portion 43a. The first elastic portion 43a is separated into an elastic portion 43a1 and an elastic portion 43a2 by the slit 48a. Thus, the elastic portion 43a1 and the elastic portion 43a2 can deform independently.

[0087] Similarly, a slit 48b is formed in the second elastic portion 43b. The second elastic portion 43b is separated into elastic portion 43b1 and elastic portion 43b2 through the slit 48b. Thus, elastic portion 43b1 and elastic portion 43b2 can deform independently.

[0088] According to circuit breaker 1A, the fixed contact 21 and the movable contact 41 are in contact at four points, ensuring the continuity of the first terminal piece 2 and the movable piece 4A. Therefore, even when a strong impact is applied to circuit breaker 1A, it is easy to maintain the continuity of the first terminal piece 2 and the movable piece 4A, suppressing the momentary interruption of the current supplied to the load.

[0089] In circuit breaker 1A, it is preferable that the natural vibration frequencies of elastic parts 43a1, 43a2, 43b1, and 43b2 are different. Furthermore, it is preferable that the natural vibration frequencies of elastic parts 43a1 and 43b1, as well as elastic parts 43a2 and 43b2, are different. Moreover, the adjustment of the natural vibration frequencies can be achieved in the same way as the movable piece 4.

[0090] By utilizing elastic parts 43a1 and 43a2, as well as elastic parts 43b1 and 43b2, to make the inherent vibration frequencies different, even when the circuit breaker 1A is subjected to impacts of various intensities, it is possible to suppress the simultaneous separation of the first movable contact 41a and the second movable contact 41b from the fixed contact 21, thereby suppressing the momentary interruption of the current supplied to the load.

[0091] Figure 7 Is as Figure 1 A perspective view of circuit breaker 1B, another variation of circuit breaker 1. The structure of circuit breaker 1, etc., described above, can be used for the following undescribed parts of circuit breaker 1B.

[0092] Circuit breaker 1B includes a first terminal piece 2, a second terminal piece 3, a movable piece 4B, a thermal response element 5, a PTC thermistor 6, etc.

[0093] The movable piece 4B includes a pair of movable pieces. That is, the movable piece 4B includes a first movable piece 4a and a second movable piece 4b. The first movable piece 4a and the second movable piece 4b are arranged in the long side direction of the circuit breaker 1B.

[0094] The first movable piece 4a has a first movable contact 41a, a contact area 42a, and a first elastic portion 43a. Preferably, a protrusion 44a is formed in the first elastic portion 43a. The second movable piece 4b has a second movable contact 41b, a contact area 42b, and a second elastic portion 43b. Preferably, a protrusion 44b is formed in the second elastic portion 43b. The natural frequency of the first portion 45a of the first movable piece 4a and the natural frequency of the second portion 45b of the second movable piece 4b are the same as those of the circuit breaker 1.

[0095] In movable piece 4B, it is also possible to... Figure 6 As shown in the movable piece 4A, a slit can be formed in the first elastic portion 43a of the movable piece 4a, or a slit can be formed in the second elastic portion 43b of the movable piece 4b.

[0096] In addition, movable piece 4B may also contain two or more pairs of movable pieces.

[0097] The circuit breaker 1 and the like of the present invention have been described in detail above, but the present invention is not limited to the specific embodiments described above, but can be implemented in various ways. That is, the circuit breaker 1 and the like shall at least include: a first terminal piece 2 having a fixed contact 21; a movable piece 4 having a movable contact 41, which is pressed against the fixed contact 21 to make them contact; a thermal response element 5 that deforms with temperature changes, thereby causing the movable piece 4 to move and causing the movable contact 41 to separate from the fixed contact 21; and a second terminal piece 3 electrically connected to the movable piece 4, wherein the movable contact 41 includes a first movable contact 41a disposed at a first end 40a in the long side direction of the movable piece 4 and a second movable contact 41b disposed at a second end 40b in the long side direction of the movable piece 4, and the fixed contact 21 may include a first fixed contact 21a disposed at a position that can be contacted by the first movable contact 41a and a second fixed contact 21b disposed at a position that can be contacted by the second movable contact 41b.

[0098] For example, the movable piece 4 can be formed by stacking metals such as bimetallic or trimetallic metals, thereby integrally forming the movable piece 4 and the thermal response element 5. In this case, the structure of the circuit breaker 1, etc., is simplified.

[0099] In addition, this embodiment has a self-holding circuit based on the PTC thermistor 6, but it can be applied even if such a structure is omitted, and the resistance between terminals can be reduced.

[0100] Furthermore, in circuit breaker 1A, three or more pairs of movable contacts 41 may be provided on the movable piece 4.

[0101] In addition, the circuit breaker 1 of the present invention can also be widely used in secondary battery packs, safety circuits for electrical equipment, etc. Figure 8 This refers to a secondary battery pack 500. The secondary battery pack 500 includes a secondary battery 501 and a circuit breaker 1 installed in the output circuit of the secondary battery 501. Figure 9 This refers to a safety circuit 502 for electrical equipment. The safety circuit 502 includes a circuit breaker 1 connected in series in the output circuit of the secondary battery 501. It can also be formed as part of the safety circuit 502 via a cable including a connector such as the circuit breaker 1.

[0102] (Label Explanation)

[0103] 1. Circuit breaker

[0104] 1A circuit breaker

[0105] 2 First terminal piece

[0106] 3 Second terminal piece

[0107] 4 movable pieces

[0108] 4A movable piece

[0109] 5 Thermal Response Elements

[0110] 21 Fixed Contacts

[0111] 21a First fixed contact

[0112] 21b Second fixed contact

[0113] 22 First terminal

[0114] 32 Second terminal

[0115] 33a convex part

[0116] 33b convex part

[0117] 40a First end

[0118] 40b Second end

[0119] 41 Movable contact

[0120] 41a First movable contact

[0121] 41b Second movable contact

[0122] 42 First contact area

[0123] 44a protrusion

[0124] 44b protrusion

[0125] 45a Part 1

[0126] 45b Part Two

[0127] 46a Bend

[0128] 46b Bend

[0129] 47a Bend

[0130] 47b Bend

[0131] 51 Top

[0132] 500 secondary battery pack

[0133] 501 Secondary Battery

[0134] 502 Safety Circuit.

Claims

1. A circuit breaker comprising: a first terminal piece formed with a fixed contact; a movable piece having a movable contact and bringing the movable contact into contact with the fixed contact by pressing the movable contact to the fixed contact; a thermal response element deforming with a change in temperature, thereby causing the movable piece to act in such a manner that the movable contact is separated from the fixed contact; a second terminal piece electrically connected to the movable piece; and a housing including a housing main body and a cover member mounted to an upper surface of the housing main body, the first terminal piece, the movable piece, the thermal response element, and the second terminal piece being housed in the housing, the first terminal piece being embedded in the housing main body, the second terminal piece being embedded in the cover member, the movable contact including a first movable contact disposed at a first end portion in a longitudinal direction of the movable piece and a second movable contact disposed at a second end portion in the longitudinal direction of the movable piece, the fixed contact including a first fixed contact disposed at a position where the first movable contact can come into contact and a second fixed contact disposed at a position where the second movable contact can come into contact, the movable piece having a first contact region contacting the second terminal piece between the first movable contact and the second movable contact, a first elastic portion disposed between the first movable contact and the first contact region, and a second elastic portion disposed between the second movable contact and the first contact region, the thermal response element having a top portion protruding toward the movable piece, the first contact region being disposed in an area overlapping the top portion and the first and second elastic portions being disposed in areas not overlapping the top portion, as viewed in a thickness direction of the movable piece.

2. The circuit breaker according to claim 1, wherein an inherent vibration frequency of the movable piece is different between a first portion from the first contact region to the side of the first end portion and a second portion from the first contact region to the side of the second end portion.

3. The circuit breaker according to claim 1, wherein the movable piece has a first bent portion bent in such a manner that the first movable contact approaches the first fixed contact.

4. The circuit breaker according to claim 3, wherein the movable piece has a first protrusion protruding toward the thermal response element between the first movable contact and the first bent portion.

5. The circuit breaker according to claim 4, wherein the second terminal piece has a second contact region contacting the first contact region and has a first projection protruding toward the movable piece between the first protrusion and the second contact region.

6. A safety circuit for an electrical device, comprising the circuit breaker according to any one of claims 1 to 5.

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

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