Breaker and safety circuit for electric apparatus

Abstract

This breaker (100) is provided with: a first terminal piece (1) that is connected to an external circuit; a second terminal piece (2) that has a fixed contact (21); a movable piece (4) that has an elastic part (43) and a movable contact (41), is connected to the first terminal piece (1), and presses the movable contact (41) to bring the movable contact (41) into contact with the fixed contact (21); a thermally-actuated element (5) that is in contact with the movable piece (4) and deforms as the temperature changes, thereby causing the movable piece (4) to transition from a conductive state to a cut-off state; and a resin base (7) for accommodating the first terminal piece (1), the second terminal piece (2), the movable piece (4), and the thermally-actuated element (5). The breaker (100) further includes a heat detection terminal (6) that protrudes from the bottom surface of the resin base (7), receives heat from the outside of the resin base (7), and transmits the heat to the thermally-actuated element (5).

Description

Circuit breaker and safety circuit for electrical equipment

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[0001] The present invention relates to a small circuit breaker or the like built into electrical equipment or the like.

[0002] Conventionally, a circuit breaker provided with a fixed contact, a movable piece having a movable contact, and a thermal responsive element has been known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2014-154518

[0004] In order to improve the safety of electrical equipment in the circuit breaker shown in Patent Document 1, it is important that the thermal responsive element reacts sensitively according to the temperature rise of the heat detection target. However, in the circuit breaker shown in Patent Document 1, when the heat detection target is separated from the resin base or terminals of the circuit breaker, the reaction sensitivity of the thermal responsive element may become dull.

[0005] The present invention has been devised in view of the above actual situation, and the main object thereof is to provide a circuit breaker capable of making the reaction sensitivity of the thermal responsive element good.

[0006] The circuit breaker of the present invention includes: a first terminal piece connected to an external circuit; a second terminal piece having a fixed contact; a movable piece formed in a plate shape having a longitudinal direction, having an elastic portion that elastically deformes and a movable contact at one end portion thereof, the other end portion being connected to the first terminal piece, and pressing the movable contact against the fixed contact to bring them into contact; a thermal responsive element that contacts the movable piece and, by deforming with a temperature change, shifts the movable piece from a conduction state in which the movable contact contacts the fixed contact to an interruption state in which the movable contact is separated from the fixed contact; and a resin base for housing the first terminal piece, the second terminal piece, the movable piece, and the thermal responsive element, and includes a heat detection terminal that protrudes from the bottom surface of the resin base and receives heat from the outside of the resin base and transmits it to the thermal responsive element.

[0007] Since the circuit breaker of the present invention has the above configuration, the reaction sensitivity of the thermal responsive element can be made good.

[0008] A perspective view showing the state of a circuit breaker according to one embodiment of the present invention before assembly. A cross-sectional view showing the circuit breaker in a normal energized state. A cross-sectional view showing the circuit breaker in an abnormal state. A perspective view showing the resin base in which the first and second terminal pieces of Figure 1 are embedded. A perspective view showing a modified example of the resin base of Figure 4. A circuit diagram of a safety circuit for electrical equipment on which the circuit breaker of Figure 1 is mounted.

[0009] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. It should be understood that the drawings contain exaggerations and representations that differ from the actual dimensional ratios of the structure in order to aid in understanding the content of the invention. Furthermore, the same or common elements are denoted by the same reference numerals throughout each embodiment, and redundant explanations are omitted. Moreover, the specific configurations shown in the embodiments and drawings are for the purpose of understanding the content of the present invention, and the present invention is not limited to the specific configurations shown in the drawings.

[0010] A circuit breaker according to one embodiment of the present invention will be described with reference to the drawings. Figures 1 to 3 show the configuration of the circuit breaker 100 of the present invention. The circuit breaker 100 is mounted on electrical equipment and protects the electrical equipment from excessive temperature rise or overcurrent. The electrical equipment on which the circuit breaker 100 is mounted is not particularly limited, but for example, it is desirable from a safety standpoint to mount the circuit breaker 100 on electrical equipment that carries a large current and experiences a significant temperature rise during operation.

[0011] As shown in Figure 1, the circuit breaker 100 is composed of a first terminal piece 1 having a first terminal 11, a second terminal piece 2 having a fixed contact 21 and a second terminal 22, a movable piece 4 having a movable contact 41 at one end, a thermally responsive element 5 that deforms in response to temperature changes, and a resin base 7 that houses the first terminal piece 1, the second terminal piece 2, the movable piece 4, and the thermally responsive element 5.

[0012] The first terminal piece 1 is formed by press-forming a metal plate mainly composed of copper (or other metal plates such as copper-titanium alloy, nickel silver, or brass), and is embedded in the resin base 7 by insert molding. The first terminal 11 protrudes from the first end face 71 in the longitudinal direction D1 of the resin base 7 to the outside of the resin base 7 and is connected to the external circuit of the breaker 100 (circuit inside the electrical equipment).

[0013] The first terminal piece 1 has a connecting portion 12 which connects to the movable piece 4. The connecting portion 12 is exposed to the housing space 73 inside the resin base 7.

[0014] The second terminal piece 2, like the first terminal piece 1, is formed by press-forming a metal plate mainly composed of copper, and is embedded in the resin base 7 by insert molding.

[0015] The fixed contact 21 protrudes toward the movable contact 41. The surface of the fixed contact 21 is formed with a layer of highly conductive material such as silver, nickel, nickel-silver alloy, copper-silver alloy, or gold-silver alloy by cladding, plating, or coating. The fixed contact 21 is formed in a position opposite the movable contact 41 of the second terminal piece 2 and is exposed in the housing space 73 inside the resin base 7.

[0016] In this application, unless otherwise specified for convenience, the side of the second terminal piece 2 on which the fixed contact 21 is formed (i.e., the upper side in Figure 1) is described as the top surface, and the opposite side is described as the bottom surface. The same applies to other components, such as the first terminal piece 1, the movable piece 4, the thermal responsive element 5, and the resin base 7. These descriptions do not limit the orientation and position of the breaker 100 when it is mounted in electrical equipment.

[0017] The second terminal 22 protrudes from the second end face 72 opposite to the first end face 71 of the resin base 7 and is connected to the external circuit described above.

[0018] The movable piece 4 is formed in a plate shape by press-forming a metal material mainly composed of copper or the like. The movable piece 4 is formed in an arm shape symmetrical with respect to the center line in the longitudinal direction D1.

[0019] The movable piece 4 may be formed integrally with the first terminal piece 1. In this case, the first terminal 11 is formed on a part of the movable piece 4 (the side of the connecting portion 42 described later), and the first terminal 11 protrudes from the first end face 71 of the resin base 7.

[0020] The movable contact 41 protrudes toward the fixed contact 21. The surface of the movable contact 41 is formed on the bottom surface of the movable piece 4 using the same material as the fixed contact 21, and is joined to the tip of the movable piece 4 by welding, cladding, crimping, or other methods.

[0021] A connection portion 42 is formed at the other end of the movable piece 4, which is electrically connected to the connection portion 12 of the first terminal piece 1. The top surface of the connection portion 12 of the first terminal piece 1 and the bottom surface of the connection portion 42 of the movable piece 4 are fixed together, for example, by laser welding. Laser welding is a welding method that joins workpieces together by irradiating them with laser light (in this embodiment, the first terminal piece 1 and the movable piece 4) and locally melting and solidifying the workpieces. Laser welding also includes welding using a fine fiber laser. Laser welding marks are formed on the surface of the workpiece irradiated with laser light, and these marks have a different form from welding marks made by other welding methods (for example, resistance welding using Joule heating).

[0022] 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. As a result, the movable contact 41 is provided at one end of the elastic portion 43, and the connecting portion 42 is provided on the opposite side of the elastic portion 43 from the movable contact 41.

[0023] The movable piece 4 is fixed by being secured to the connection portion 12 of the first terminal piece 1 at the connection portion 42, and as the elastic portion 43 elastically deforms, the movable contact 41 formed at its tip is pressed against the fixed contact 21 and makes contact, allowing current to flow between the second terminal piece 2 and the movable piece 4. Since the movable piece 4 and the first terminal piece 1 are electrically connected at the connection portion 12 and the connection portion 42, current can flow between the first terminal piece 1 and the second terminal piece 2.

[0024] The movable piece 4 may be curved or bent by press working in the elastic portion 43. The degree of curvature or bend can be appropriately set considering the elastic force at the operating temperature and return temperature, the pressing force at the contact point, etc. In addition, a projection 44 is formed on the bottom surface of the elastic portion 43, facing the thermally responsive element 5. The projection 44 comes into contact with the main body 51 of the thermally responsive element 5 which has been deformed by heat, and the deformation of the thermally responsive element 5 is transmitted to the elastic portion 43 via the projection 44 (see Figure 3).

[0025] The movable piece 4 has an engaging portion 45 at its end edge on the connection portion 42 side for engaging with the thermally responsive element 5. In this embodiment, the engaging portion 45 is formed by a through hole that penetrates the movable piece 4. The movable piece 4 has a protruding portion 46 at its end edge on the connection portion 42 side. The protruding portion 46 protrudes on the side opposite to the connection portion 12 of the first terminal piece 1 (see Figure 1). In this embodiment, the protruding portion 46 is formed by bending the end edge of the movable piece 4 on the connection portion 42 side on the side opposite to the connection portion 12 of the first terminal piece 1. The engaging portion 45 is formed on the protruding portion 46.

[0026] The movable piece 4 has a bent portion 47 at its edge on the side facing the movable contact 41. The bent portion 47 is bent in the vicinity of the movable contact 41, on the opposite side from the movable contact 41, and protrudes (see Figure 1).

[0027] The thermally responsive element 5 transitions from a conductive state in which the movable contact 41 is in contact with the fixed contact 21 to a disconnected state in which the movable contact 41 is separated from the fixed contact 21. The thermally responsive element 5 has a central main body portion 51 and protrusions 52 and 53 formed to protrude from the main body portion 51 on both sides in the longitudinal direction D1 of the movable piece 4.

[0028] The main body 51 of the thermal-responsive element 5 has an initial shape in which the cross-section is curved in an arc shape so as to be concave on the side of the movable piece 4, and is formed by laminating thin sheet materials with different coefficients of thermal expansion. When the operating temperature is reached due to overheating, the curved shape of the thermal-responsive element 5 reverses with a snapping motion, and returns to its original shape when it cools below the return temperature. The initial shape of the thermal-responsive element 5 can be formed by press working. As long as the elastic part 43 of the movable piece 4 is pulled up by the reverse bending operation of the thermal-responsive element 5 at the desired temperature and returns to its original shape due to the elastic force of the elastic part 43, the material and shape of the thermal-responsive element 5 are not particularly limited, but a rectangular shape is desirable from the viewpoint of productivity and efficiency of the reverse bending operation, and a rectangle close to a square is desirable in order to efficiently push up the elastic part 43 while being small. Furthermore, as the material for the thermally responsive element 5, for example, a combination of two materials with different coefficients of thermal expansion, such as a copper-nickel-manganese alloy or nickel-chromium-iron alloy on the high-expansion side and an iron-nickel alloy, or various alloys such as nickel silver, brass, and stainless steel on the low-expansion side, may be used depending on the required conditions.

[0029] As shown in Figure 1, after the connecting portion 42 of the movable piece 4 is fixed to the connecting portion 12 of the first terminal piece 1, the protruding portion 52 on the engaging portion 45 side is inserted into the through hole that constitutes the engaging portion 45 of the movable piece 4 and engages with the engaging portion 45. As a result, the pair of protruding portions 53 are positioned to correspond to the bent portion 47 of the movable piece 4. Then, as the bent portion 47 is bent toward the top surface of the protruding portion 53, the protruding portion 53 engages with the bent portion 47.

[0030] The protruding portion 52 engages with the engaging portion 45, and the protruding portion 52 engages with the bending portion 47, thereby assembling the thermally responsive element 5 and the movable piece 4, allowing them to operate as a single unit.

[0031] The resin base 7 is molded from, for example, a thermoplastic resin such as flame-retardant polyamide, heat-resistant polyphenylene sulfide (PPS), liquid crystal polymer (LCP), or polybutylene terephthalate (PBT), or a thermosetting resin such as epoxy or phenolic resin. Other materials may be used if they provide properties equivalent to or better than those of the resins mentioned above.

[0032] The resin base 7 is formed in a rectangular shape having a longitudinal direction D1, and the longitudinal direction D1 of the resin base 7 coincides with the longitudinal direction D1 of the movable piece 4.

[0033] A housing space 73 for accommodating the movable piece 4 and the thermal responsive element 5 is formed on the top surface of the resin base 7. The resin base 7 in this embodiment has a configuration in which the top surface of the housing space 73 is open. With the top surface of the resin base 7 open, heat from the outside (above) of the breaker 100 can easily enter the housing space 73, which can improve the reaction sensitivity of the thermal responsive element 5. Alternatively, a lid member may be attached to the top surface of the resin base 7.

[0034] In this embodiment, the resin base 7 has a through hole 75 that extends from the housing space 73 to the bottom surface 74. Heat from the outside (below) of the breaker 100 enters through the through hole 75, which further improves the reaction sensitivity of the thermally responsive element 5.

[0035] Figures 2 and 3 show an overview of the operation of the circuit breaker 100. Figure 2 shows the operation of the circuit breaker 100 under normal temperature conditions. Here, "normal temperature conditions" refers to the state of the circuit breaker 100 at the temperature during normal operation as assumed by the electrical equipment, and also includes the state in the temperature range that rises with the normal operation of the electrical equipment.

[0036] Under normal temperature conditions, the thermally responsive element 5 maintains its initial shape before reverse bending. The thermally responsive element 5 in its initial shape is in contact with the movable piece 4 at at least one point (in this example, at two points, the protrusions 52 and 53). This contact between the thermally responsive element 5 and the movable piece 4 does not affect the deformation of the movable piece 4. Therefore, the movable contact 41 is pressed towards the fixed contact 21 by the elastic part 43, causing the movable contact 41 and the fixed contact 21 to come into contact, and enabling electrical communication between the first terminal piece 1 and the second terminal piece 2 of the breaker 100 via the elastic part 43.

[0037] Furthermore, the contact between the thermally responsive element 5 and the movable piece 4 maintains a state in which heat can be conducted from the movable piece 4 to the thermally responsive element 5.

[0038] Figure 3 shows the operation of the circuit breaker 100 under abnormal temperature conditions. When electrical equipment malfunctions, the load on the equipment increases, causing it to overheat beyond its normal temperature. As the electrical equipment overheats, the temperature of the thermal responsive element 5 rises. This temperature condition of the circuit breaker 100 is referred to as the "abnormal temperature condition."

[0039] The thermal-responsive element 5, which has a structure in which thin plates with different coefficients of thermal expansion are laminated, deforms as the temperature rises so that the curved initial shape shown in Figure 2 is corrected. Then, when the thermal-responsive element 5 reaches the operating temperature, it snaps into the opposite shape as shown in Figure 3. As a result, the thermal-responsive element 5 deforms while coming into contact with the projection 44 of the movable piece 4 and engaging with the engaging portion 45 and the bent portion 47. The tip of the elastic portion 43 is pushed up by the thermal-responsive element 5, separating the fixed contact 21 and the movable contact 41. At this time, the current flowing between the fixed contact 21 and the movable contact 41 is interrupted, and the heat generated by the electrical equipment subsides.

[0040] As the heat generated by the electrical equipment subsides and the temperature of the thermally responsive element 5 decreases and returns to the forward rotation return temperature, the thermally responsive element 5 returns to its original initial shape. Then, the elastic force of the elastic portion 43 of the movable piece 4 causes the movable contact 41 and the fixed contact 21 to make contact again, the circuit is released from its interrupted state, and returns to the conductive state shown in Figure 2.

[0041] The circuit breaker 100 of the present invention includes a thermal detection terminal 6 for detecting heat outside the circuit breaker 100. The thermal detection terminal 6 penetrates a through hole 75 in the resin base 7 and protrudes from the bottom surface 74 of the resin base 7. The thermal detection terminal 6 is positioned in contact with or close to a thermal detection target 200 (see Figures 2 and 3) in order to detect the heat (temperature) of the thermal detection target 200 located outside the circuit breaker 100 and away from the resin base, terminals, etc. "Positioned close to" means that the distance between the thermal detection terminal 6 and the thermal detection target 200 is shorter than the distance between the thermal detection target 200 and other components of the circuit breaker 100 (e.g., the resin base 7, etc.).

[0042] The heat detection terminal 6 is configured to be thermally conductive to the thermally responsive element 5 through at least one of the first terminal piece 1, the second terminal piece 2, and the movable piece 4. Thereby, the heat detected by the heat detection terminal 6 moves to the accommodation space 73 of the resin base 7 and is conducted to the thermally responsive element 5. Therefore, even if the heat detection target 200 is arranged at a position separated from the resin base 7, the first terminal 11, the second terminal 22, or the like, the reaction sensitivity of the thermally responsive element 5 can be made extremely good.

[0043] FIG. 4 shows the resin base 7 in which the first terminal piece 1 and the second terminal piece 2 are embedded. As shown in FIGS. 1 to 4, in the breaker 100 of the present embodiment, the heat detection terminal 6 is formed integrally with the first terminal piece 1. More specifically, the heat detection terminal 6 is formed at the tip of a relay portion 61 extending from the connection portion 12.

[0044] As shown in FIGS. 1 and 4, the relay portion 61 is bent from the connection portion 12 to the bottom surface 74 side of the resin base 7 at the bending portion 13, penetrates the through hole 75, and protrudes from the bottom surface 74 of the resin base 7. The heat detection terminal 6 is bent to the opposite side of the bending portion 13 at the bending portion 62, and in the present embodiment, is arranged parallel to the bottom surface 74 of the resin base 7 such a heat detection terminal 6 is formed integrally with the first terminal piece 1 when, for example, the first terminal piece 1 is press-processed.

[0045] The protruding length of the relay portion 61 is set according to, for example, the distance of the heat detection target 200 from the bottom surface 74 of the resin base 7. Further, the bending angle of the bending portion 62 is set according to, for example, the posture of the heat detection target 200 with respect to the bottom surface 74 of the resin base 7.

[0046] In the breaker 100 having the above configuration, the heat detected by the heat detection terminal 6 is conducted to the thermally responsive element 5 sequentially through the connection portion 12 of the first terminal piece 1 and the movable piece 4. Thereby, even if the heat detection target

[0047] 20 are arranged at a position separated from the resin base 7, the first terminal 11, the second terminal 22, or the like, the reaction sensitivity of the thermally responsive element 5 can be made extremely good.

[0047] As shown in FIG. 4, it is desirable that a reinforcing piece 8 be embedded in the resin base 7. The reinforcing piece 8 reinforces the resin base 7 and thus the breaker 100. By the reinforcing piece 8, the position of the movable contact 41 relative to the fixed contact 21 and the like are stabilized, and the operation of the breaker 100 is stabilized. That is, it is desirable that the breaker 100 has a reinforcing piece 8 for reinforcing the resin base 7.

[0048] The reinforcing piece 8 is formed of, for example, a metal plate mainly composed of copper or the like, similar to the first terminal piece 1. The strength and rigidity of the resin base 7 can be easily increased by a pair of reinforcing pieces 8 extending in the longitudinal direction D1 of the movable piece 4. In the breaker 100 of the present embodiment, the reinforcing pieces 8 are arranged on both sides of the through hole 75 in the short direction D2 perpendicular to the longitudinal direction D1 of the movable piece 4 and extend in the longitudinal direction D1 of the movable piece 4.

[0049] It is desirable that the reinforcing piece 8 be integrally formed with the first terminal piece 1. In the present embodiment, the reinforcing piece 8 extends from the connecting portion 12 of the first terminal piece 1 toward the second terminal piece 2 on both sides of the heat detection terminal 6 in the short direction D2 of the movable piece 4. Such a reinforcing piece 8 is formed integrally with the first terminal piece 1 when the first terminal piece 1 is press-worked together with the heat detection terminal 6.

[0050] Also, the reinforcing piece 8 may partially protrude into the through hole 75. With such a reinforcing piece 8, the reinforcing piece 8 is heated by the heat that has entered the through hole 75, so that the reaction sensitivity of the thermal response element 5 can be made even better.

[0051] As shown in FIG. 4, it is desirable that the second terminal piece 2 extend from the fixed contact 21 in the longitudinal direction D1 of the movable piece 4 and have an embedded portion 23 embedded in the resin base 7. In the embedded portion 23 of the present embodiment, the bottom surface and the side surfaces are embedded in the resin base 7, and the top surface is exposed in the accommodation space 73. The strength and rigidity of the resin base 7 can be easily increased by the embedded portion 23.

[0052] It is desirable that the reinforcing piece 8 and the embedded portion 23 overlap in at least a portion when viewed from the short-side direction D2 of the movable piece 4. In the breaker 100 of this embodiment, the reinforcing piece 8 and the embedded portion 23 overlap with each other in the region R1 shown in Figure 4.

[0053] The reinforcing piece 8 and the embedded portion 23 make it easy to increase the strength and rigidity of the resin base 7 in region R1. Furthermore, since the metal plate of the first terminal piece 1 or the second terminal piece 2 is present in any cross section perpendicular to the longitudinal direction D1 of the movable piece 4 in the resin base 7, the overall strength and rigidity of the resin base 7 can be increased even more easily.

[0054] Figure 5 shows a modified resin base 7A, which is a modified version of the resin base 7 shown in Figure 4. For parts of the breaker 100 including the resin base 7A that are not described below, the configuration of the breaker 100 including the resin base 7 described above may be adopted.

[0055] In the circuit breaker 100, which includes a resin base 7A, the first terminal piece 1A, the second terminal piece 2A, and the heat detection terminal 6A are embedded in the resin base 7A. The heat detection terminal 6A is integrally formed with the second terminal piece 2A. More specifically, the heat detection terminal 6A is formed at the tip of the relay portion 61A that extends from the peripheral portion 24 of the fixed contact 21A.

[0056] The relay portion 61A is bent from the peripheral portion 24 of the fixed contact 21A toward the bottom surface 74A of the resin base 7A, passes through the through hole 75A, and protrudes from the bottom surface 74A of the resin base 7A. The heat detection terminal 6A is bent from the relay portion 61A toward the opposite side and is arranged parallel to the bottom surface 74A of the resin base 7A. Such a heat detection terminal 6A is formed integrally with the second terminal piece 2A when the second terminal piece 2A is press-formed.

[0057] In the circuit breaker 100, which includes a resin base 7A, the heat detected by the heat detection terminal 6A is conducted to the thermal response element 5 sequentially via the fixed contact 21 and movable piece 4 of the second terminal piece 2A. As a result, even if the heat detection target 200 is located far from the resin base 7A, the first terminal 11A, or the second terminal 22A, the response sensitivity of the thermal response element 5 can be made extremely good.

[0058] As shown in Figure 5, it is desirable that a reinforcing piece 8A is embedded in the resin base 7A. In other words, it is desirable that the breaker 100 including the resin base 7A has a reinforcing piece 8A for reinforcing the resin base 7A.

[0059] The reinforcing piece 8A is formed from a metal plate mainly composed of copper, for example, similar to the second terminal piece 2A. The strength and rigidity of the resin base 7A can be easily increased by a pair of reinforcing pieces 8A extending in the longitudinal direction D1 of the movable piece 4. In the breaker 100 including the resin base 7A, the reinforcing pieces 8A extend in the longitudinal direction D1 of the movable piece 4 on both sides of the through hole 75A in the short direction D2 perpendicular to the longitudinal direction D1 of the movable piece 4.

[0060] It is preferable that the reinforcing piece 8A is integrally formed with the second terminal piece 2A. In this embodiment, the reinforcing piece 8A extends from the peripheral portion 24 of the fixed contact 21 of the second terminal piece 2A toward the first terminal piece 1A on both sides of the heat detection terminal 6A in the short direction D2 of the movable piece 4. Such a reinforcing piece 8A is formed integrally with the second terminal piece 2A together with the heat detection terminal 6A when the second terminal piece 2A is press-formed.

[0061] Furthermore, the reinforcing piece 8A may protrude in part into the through hole 75A. With such a reinforcing piece 8A, the reinforcing piece 8A is heated by the heat that enters the through hole 75A, which can further improve the reaction sensitivity of the thermally responsive element 5.

[0062] As shown in Figure 5, it is preferable that the first terminal piece 1A extends from the connection portion 12 in the longitudinal direction D1 of the movable piece 4 and has an embedded portion 13A that is embedded in the resin base 7. In this embodiment, the bottom and sides of the embedded portion 23A are embedded in the resin base 7A, and the top surface is exposed to the housing space 73A. The embedded portion 13A makes it easy to increase the strength and rigidity of the resin base 7A.

[0063] It is desirable that the reinforcing piece 8A and the embedded portion 13A overlap in at least a portion when viewed from the short side direction D2 of the movable piece 4. In the breaker 100 including the resin base 7A, the reinforcing piece 8A and the embedded portion 13A overlap with each other in the region R1 shown in Figure 5.

[0064] The reinforcing piece 8A and the embedded portion 13A make it easy to increase the strength and rigidity of the resin base 7A in region R1. Furthermore, since the metal plate of the first terminal piece 1A or the second terminal piece 2A is present in any cross section perpendicular to the longitudinal direction D1 of the movable piece 4 in the resin base 7A, the strength and rigidity of the resin base 7A can be increased even more easily.

[0065] The circuit breaker 100 of the present invention can be widely applied to safety circuits for electrical equipment. Figure 6 shows a safety circuit 500 for electrical equipment. The safety circuit 500 includes the circuit breaker 100 in series with a circuit that includes a power supply unit 501 and a load 502. In the safety circuit 500, the power supply unit 501 or the load 502 can be a heat detection target 200. The heat detection terminal 6 of the circuit breaker 100 is arranged in contact with or close to the power supply unit 501 or the load 502. With the safety circuit 500 equipped with the circuit breaker 100, it is possible to manufacture a safety circuit 500 with good reaction sensitivity of the heat-sensitive element 5.

[0066] Although the circuit breaker 100 of the present invention has been described in detail above, the present invention is not limited to the above-described specific embodiments and can be implemented in various modified forms.

[0067] [Note] The present invention includes the following embodiments.

[0068] [1] A circuit breaker comprising: a first terminal piece connected to an external circuit; a second terminal piece having a fixed contact; a movable piece formed in a plate shape having a longitudinal direction, having an elastic portion that deforms elastically and a movable contact at one end of the elastic portion, the other end of which is connected to the first terminal piece, and which presses the movable contact against the fixed contact; a thermal responsive element that deforms in response to temperature changes, contacts the movable piece, and causes the movable piece to transition from a conductive state in which the movable contact is in contact with the fixed contact to a disconnected state in which the movable contact is separated from the fixed contact; and a resin base for housing the first terminal piece, the second terminal piece, the movable piece, and the thermal responsive element, wherein the circuit breaker includes a heat detection terminal that protrudes from the bottom surface of the resin base and receives heat from outside the resin base and transmits it to the thermal responsive element. [2] The circuit breaker according to 1, wherein the heat detection terminal is integrally configured with the first terminal piece. [Invention 3] The circuit breaker according to Invention 1, wherein the heat detection terminal is integrally configured with the second terminal piece. [Invention 4] The circuit breaker according to Invention 1, further comprising a reinforcing piece extending in the longitudinal direction of the movable piece and embedded in the resin base to reinforce the resin base. [Invention 5] The circuit breaker according to Invention 4, wherein the reinforcing piece is the first terminal piece. [Invention 6] The circuit breaker according to Invention 5, wherein the second terminal piece extends in the longitudinal direction from the fixed contact and has an embedded portion embedded in the resin base. [Invention 7] The circuit breaker according to Invention 6, wherein the reinforcing piece and the embedded portion overlap in at least a portion when viewed from the short direction perpendicular to the longitudinal direction. [Invention 8] A safety circuit for electrical equipment comprising a circuit breaker according to any one of Inventions 1 to 7.

[0069] 1: First terminal piece 1A: First terminal piece 2: Second terminal piece 2A: Second terminal piece 3: Terminal piece 4: Movable piece 5: Thermally responsive element 6: Thermal detection terminal 6A: Thermal detection terminal 7: Resin base 7A: Resin base 8: Reinforcement piece 8A: Reinforcement piece 11: First terminal 11A: First terminal 13A: Buried part 21: Fixed contact 21A: Fixed contact 22: Second terminal 22A: Second terminal 23: Buried part 23A: Buried part 41: Movable contact 43: Elastic part 100: Breaker 500: Safety circuit D1: Longitudinal direction D2: Short direction

Claims

1. A circuit breaker comprising: a first terminal piece connected to an external circuit; a second terminal piece having a fixed contact; a movable piece formed in a plate shape having a longitudinal direction, having an elastic portion that deforms elastically and a movable contact at one end of the elastic portion, the other end of which is connected to the first terminal piece, and which presses the movable contact against the fixed contact; a thermal responsive element that deforms in response to temperature changes, contacts the movable piece, and causes the movable piece to transition from a conductive state in which the movable contact is in contact with the fixed contact to a disconnected state in which the movable contact is separated from the fixed contact; and a resin base for housing the first terminal piece, the second terminal piece, the movable piece, and the thermal responsive element, wherein the circuit breaker includes a heat detection terminal that protrudes from the bottom surface of the resin base and receives heat from outside the resin base and transmits it to the thermal responsive element.

2. The circuit breaker according to claim 1, wherein the heat detection terminal is integrally configured with the first terminal piece.

3. The circuit breaker according to claim 1, wherein the heat detection terminal is integrally configured with the second terminal piece.

4. The breaker according to claim 1, further comprising a reinforcing piece extending in the longitudinal direction of the movable piece and embedded in the resin base to reinforce the resin base.

5. The circuit breaker according to claim 4, wherein the reinforcing piece is the first terminal piece.

6. The circuit breaker according to claim 5, wherein the second terminal piece extends from the fixed contact in the longitudinal direction and has an embedded portion embedded in the resin base.

7. The breaker according to claim 6, wherein the reinforcing piece and the embedded portion overlap in at least a portion when viewed from the short direction perpendicular to the longitudinal direction.

8. A safety circuit for electrical equipment comprising a circuit breaker according to any one of claims 1 to 7.

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