breaker

Abstract

The present invention realizes a breaker of which the outer shape is miniaturized while ensuring reliable connection of an elastic arm plate and a terminal plate and arrangement thereof in a fixed position of a case, thus being most suitable for surface mount device (SMD) applications. The breaker comprises a fixed contact metal plate 4 having a fixed contact 5, an elastic arm plate 6 having a movable contact 7, a terminal plate 3 to which the elastic arm plate 6 is fixed, a case 1, and a bimetal 8 for switching the movable contact 7 from on to off. The case 1 is made of plastic and has a hollow storage space 20 inside. Connection terminals 4X, 3X are disposed at respective end parts 1C of the bottom surface of the case 1. The terminal plate 3 includes a lower welding plate 3A to which an upper welding plate 6B is welded in a laminated state via laser welding sections 30. The connection terminals 3X are connected to the side edges of the lower welding plate 3A, which extends in the width direction of the case 1, via rising sections 3B. The rising sections 3B are embedded in the case 1. The lateral width (W1) of the lower welding plate 3A is wider than the lateral width (W2) of the upper welding plate 6B.

Description

breaker

[0001] The present invention relates to a breaker that detects temperature with a bimetal, which elastically deforms an elastic arm plate to separate a movable contact from a fixed contact and switch to the OFF state, and in particular to a breaker that is ideal for SMDs (Surface Mount Devices) that are mounted on a circuit board by methods such as reflow soldering.

[0002] Safety can be improved for devices such as battery packs and motors by cutting off the current when the temperature becomes abnormally high. To achieve this, small micro-breakers are used, which switch the contacts off when a set temperature is reached. For example, a battery pack containing a lithium-ion battery can become hot when it is charged or discharged under abnormal conditions, so a small breaker is built into the protection circuit to cut off the current at abnormally high temperatures, ensuring safety. In addition, motors and other devices can become abnormally hot when they are overloaded or when an abnormal current is flowing, so in these conditions the breaker cuts off the current to protect the motor.

[0003] Microbreakers have been developed for such applications, using a bimetal to detect temperature rise and separate the movable contact from the fixed contact, switching the breaker to the OFF state. A microbreaker uses a bimetal to detect temperature and separate the movable contact from the fixed contact, switching the breaker to the OFF state. When the temperature exceeds a set temperature, the bimetal reverses, deforming to push up the elastic arm plate that secures the movable contact at its tip, separating the movable contact from the fixed contact and switching the breaker to the OFF state, interrupting the current. When the temperature drops and the bimetal returns to its original shape, the elasticity of the elastic arm plate brings the movable contact into contact with the fixed contact, restoring the breaker to the ON state. When the elastic arm plate is not pushed up by the bimetal, i.e., when the bimetal does not reverse due to temperature, it elastically presses the movable contact against the fixed contact. In other words, in this state, the elasticity of the elastic arm plate keeps the movable contact in contact with the fixed contact, maintaining the ON state.

[0004] In the microbreaker described above, the resilient arm plate and the connection terminal are not formed as a single metal plate, i.e., the resilient arm plate made of a resilient metal plate is not extended to the outside of the case as a connection terminal, but a terminal plate made of a metal plate with excellent conductivity is used as the connection terminal, thereby enabling a desirable electrical connection to the circuit board. Since this microbreaker can be electrically connected by laser welding the resilient arm plate and the terminal plate, the applicant of the present application developed an SMD (surface mount) breaker (Patent Document 1) in which the resilient arm plate and the terminal plate are laser welded together using a unique structure in order to achieve desirable laser welding.

[0005] JP 2023-54993 A JP 2018-206559 A

[0006] The breaker 800 (microbreaker) described in Patent Document 1 shown in Fig. 18 has the advantage that the elastic arm plate and terminal plate 803 can be firmly connected while being electrically connected stably by laser welding, but has the disadvantage that the terminal plate 803, including the raised portion, protrudes from the case, making the outer shape large, as shown in the figure. With the aim of reducing the outer shape, a breaker 900 has been developed in which the terminal plate 903 has a unique shape, as shown in Fig. 19 (Patent Document 2).

[0007] The breaker 900 of Patent Document 2 has a resilient arm plate 906 built into the case, which is connected to a terminal plate 903 inside the case, with a portion of the terminal plate 903 extending outside the case to serve as a connection terminal. This structure has the drawback of making it difficult to reliably and stably laser-weld the resilient arm plate 906 and the terminal plate 903 together. This is because, as shown in the perspective view of Figure 19 and the enlarged cross-sectional view of Figure 20, the plastic case 901 is positioned on both sides of the terminal plate 903, making it difficult to precisely position the terminal plate 903 and the plastic on both sides in the same plane, making it difficult to stack the terminal plate 903 and the resilient arm plate 906 without gaps. Terminal plate 903, which does not have the surfaces of the plastic on both sides in the same plane, makes it difficult to reliably and securely adhere the resilient arm plate 906 to the terminal plate 903 without gaps during the laser welding process. In laser welding, it is important to weld the two metal plates tightly together without any gaps, and even a slight gap between the metal plates during the laser welding process can hinder stable laser welding. A resilient arm plate 906 that is not reliably and stably welded to the terminal plate 903 has the disadvantage of being unable to consistently achieve stable contact between the movable contact and the fixed contact due to low contact resistance. Contacts with increased contact resistance have the disadvantage of increasing power loss in the on-state and increasing the amount of Joule heat generated. Since the temperature increase due to Joule heat can cause the bimetal to reverse, there is also the disadvantage that in an environment where the ambient temperature is lower than the set temperature, the bimetal may reverse due to its own heat generation, causing the bimetal to switch to the off-state.

[0008] The present invention was developed with the aim of further resolving the above drawbacks, and one of the objects of the present invention is to provide a breaker that is optimal for SMD (surface mount device) and can be compact in size while securely connecting the elastic arm plate and terminal plate and placing them in a fixed position in the case.

[0009] A breaker according to one embodiment of the present invention has all of the configurations described in (a) through (i). (a) The breaker comprises: a fixed contact metal plate having a fixed contact; a resilient arm plate having a movable contact at its tip, positioned opposite the fixed contact; a terminal plate formed by fixing an upper welding plate at the rear end of the resilient arm plate via a laser weld; a plastic case to which the terminal plate and the fixed contact metal plate are fixed; and a bimetal that presses the resilient arm plate to switch the movable contact from on to off. (b) The case is made of plastic and has a hollow storage space therein in which the resilient arm plate is disposed. (c) The case has connection terminals electrically connected to the fixed contact metal plate and connection terminals electrically connected to the resilient arm plate, disposed at each end of the bottom surface. (d) The terminal plate comprises a lower welding plate formed by welding the upper welding plate of the resilient arm plate, exposed in the storage space of the case, in a stacked state. (e) The terminal board connects the connection terminal to the side edge of the lower weld plate extending in the width direction of the case via a raised portion. (f) The terminal board has a connection terminal connected to the lower weld plate via a raised portion, which is located at the end of the bottom surface of the case. (g) The raised portion penetrates the case and is embedded in the plastic of the case in a plane parallel to the width direction of the case, with the lower weld plate located in the storage space and the connection terminal located on the bottom surface of the case. (h) The width (W1) of the lower weld plate is wider than the width (W2) of the upper weld plate, and the upper and lower weld plates are closely attached and connected by a laser weld. (i) The connection terminal is located on the bottom surface of the case in an orientation extending vertically of the case from the connection point with the raised portion toward the tip.

[0010] The above breaker has the advantage that it can be placed in a fixed position in the case by reliably connecting the elastic arm plate and the terminal plate, while also being compact in size, making it ideal for SMD (surface mount devices).

[0011] 1 is a schematic perspective view of a breaker according to an embodiment of the present invention; FIG. 2 is a schematic perspective view of the breaker shown in FIG. 1, viewed obliquely from below; FIG. 3 is a schematic perspective view of a terminal plate and a resilient arm plate; FIG. 4 is a schematic plan view of the terminal plate and a fixed contact metal plate; FIG. 5 is a schematic plan view of the terminal plate, the fixed contact metal plate, and the resilient arm plate; FIG. 6 is a schematic vertical cross-sectional view of the breaker shown in FIG. 1, taken along line VI-VI; FIG. 7 is a schematic horizontal cross-sectional view of the breaker; FIG. 8 is a schematic cross-sectional view showing an example of a laser welded portion where the terminal plate and the resilient arm plate are laser-welded; FIG. 9 is a schematic cross-sectional view showing another example of a laser welded portion; FIG. 10 is a schematic cross-sectional view showing another example of a laser welded portion; FIG. 11 is a schematic vertical cross-sectional view showing another example of a rising portion; FIG. 12 is a schematic cross-sectional view showing a state where the terminal plate and the resilient arm plate are laser-welded; FIG. 13 is a schematic perspective view of a breaker according to another embodiment of the present invention, viewed obliquely from below; FIG. 14 is a schematic perspective view of the terminal plate and the resilient arm plate; FIG. 15 is a schematic plan view of the terminal plate, the fixed contact metal plate, and the resilient arm plate; FIG. 16 is a schematic plan view of the terminal plate and the fixed contact metal plate; FIG. 17 is a schematic perspective view of the terminal plate and the fixed contact metal plate, viewed obliquely from below; FIG. 18 is a schematic perspective view of a breaker according to a conventional example; FIG. 19 is a schematic perspective view of the terminal plate and the resilient arm plate according to a conventional example. FIG. 10 is a schematic cross-sectional view of a conventional breaker.

[0012] The present invention will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper," "lower," and other terms incorporating these terms) will be used as necessary. However, the use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Furthermore, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components. Furthermore, the embodiments described below are illustrative examples of the technical concept of the present invention and do not limit the scope of the present invention. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, the content described in one embodiment or example may also be applicable to other embodiments or examples. Furthermore, the sizes and positional relationships of components shown in the drawings may be exaggerated for clarity.

[0013] A breaker according to one embodiment of the present invention comprises all of the components (a) through (i). (a) The breaker comprises a fixed contact metal plate having a fixed contact, a resilient arm plate having a movable contact at its tip, positioned opposite the fixed contact, a terminal plate formed by fixing an upper welding plate at the rear end of the resilient arm plate via a laser welded portion, a plastic case to which the terminal plate and the fixed contact metal plate are fixed, and a bimetal that presses the resilient arm plate to switch the movable contact from on to off. (b) The case is made of plastic and has a hollow storage space therein in which the resilient arm plate is disposed. (c) The case has connection terminals electrically connected to the fixed contact metal plate and connection terminals electrically connected to the resilient arm plate disposed at each end of the bottom surface. (d) The terminal plate comprises a lower welding plate formed by welding the upper welding plate of the resilient arm plate, exposed in the storage space of the case, in a stacked state. (e) The terminal board connects the connection terminal to the side edge of the lower weld plate extending in the width direction of the case via a raised portion. (f) The terminal board has a connection terminal connected to the lower weld plate via a raised portion, which is located at the end of the bottom surface of the case. (g) The raised portion penetrates the case and is embedded in the plastic of the case in a plane parallel to the width direction of the case, with the lower weld plate located in the storage space and the connection terminal located on the bottom surface of the case. (h) The width (W1) of the lower weld plate is wider than the width (W2) of the upper weld plate, and the upper and lower weld plates are closely attached and connected by a laser weld. (i) The connection terminal is located on the bottom surface of the case in an orientation extending vertically of the case from the connection point with the raised portion toward the tip.

[0014] The above breakers have the advantage of being able to reliably connect the resilient arm plate and terminal plate and place them in their designated positions in the case, while still allowing for a compact external form that is optimal for SMD (surface mount devices). The resilient arm plate and terminal plate can be reliably placed in their designated positions in the case because the terminal plate can be fixed in its designated position in the case without misalignment, and the resilient arm plate can be reliably connected to the terminal plate by laser welding. The compact external form that is optimal for SMD (surface mount devices) is possible because the lower welding plate of the terminal plate is located inside the case, the connection terminal is located on the bottom surface outside the case, and the raised portion connecting the lower welding plate and the connection terminal is embedded in the plastic of the case so that it penetrates the case.

[0015] Furthermore, the reason why the resilient arm plate and the terminal plate can be firmly connected is that the raised portions of the terminal plate are not provided at both ends of the lower welding plate as in conventional breakers, but are connected to the side edges of the lower welding plate, making the width (W1) of the lower welding plate wider than the width (W2) of the upper welding plate, and the upper welding plate of the resilient arm plate can be positioned inside the lower welding plate and laser welded. The upper welding plate, which is positioned inside the lower welding plate, can be tightly attached to the surface of the lower welding plate with no gaps, so that when a laser beam is irradiated onto the surface of the upper welding plate in this state, both the upper and lower welding plates can be melted in tight contact and reliably welded.

[0016] Another embodiment of the breaker of the present invention has a structure including a pair of connection terminals in which terminal plates are arranged apart from each other, and the pair of connection terminals can be arranged at the corners of the bottom surface of the case.

[0017] In another embodiment of the present invention, the breaker can form a laser weld into one or more linear weld lines.

[0018] Another embodiment of the breaker of the present invention allows for laser welding to one or more weld spots.

[0019] In another embodiment of the breaker of the present invention, the thickness of the elastic arm plate is 50 μm or more and 200 μm or less, and the breaker can be a micro-breaker.

[0020] In another embodiment of the breaker of the present invention, the case has an outer wall in which a fixed contact metal plate and a terminal plate are embedded, and the inside of the outer wall is used as a storage space for placing an elastic arm plate, with an exposed portion in which the lower welding plate of the terminal plate is exposed within the storage space, and the terminal plate can be laser welded by stacking the upper welding plate of the elastic arm plate on the lower welding plate.

[0021] In a breaker according to another embodiment of the present invention, the fixed contacts and the movable contacts can be activated contacts that have been activated by ultrasonic vibrations in a current-carrying state. (Embodiment 1)

[0022] The breaker 100 shown in Figures 1 to 12 below is an optimal breaker for SMD (surface mounted devices) mounted on a circuit board, and is primarily used built into battery packs and the like. The breaker in a battery pack deforms the built-in bimetal to cut off the current when the battery or ambient temperature becomes high, or when the battery pack is used in an abnormal condition. However, the present invention does not specify the use of the breaker, and can be used for breakers used in all applications that detect temperature rises and cut off the current, such as in motors. (Breaker 100)

[0023] 1 to 12 show an SMD breaker 100. This breaker 100 comprises a fixed contact metal plate 4 having a fixed contact 5, a resilient arm plate 6 with a movable contact 7 located opposite the fixed contact 5, a terminal plate 3 to which a rear end 6E of the resilient arm plate 6 is connected by a laser welded portion 30, a bimetal 8 that switches the resilient arm plate 6 on and off, and a case 1 that houses the fixed contact 5 of the fixed contact metal plate 4 and the movable contact 7 of the resilient arm plate 6 and that also houses the bimetal 8 and fixes the fixed contact metal plate 4 and the terminal plate 3 in fixed positions. When the ambient temperature rises to a high temperature, this breaker 100 detects this temperature rise and deforms the bimetal 8, which presses the resilient arm plate 6, separating the movable contact 7 from the fixed contact 5 and switching the contact to the OFF state. When the ambient temperature drops to a predetermined temperature, the elastic arm plate 6 and the bimetal 8 return to their original positions, bringing the movable contact 7 into contact with the fixed contact 5 and switching the breaker 100 to the ON state.

[0024] 1 to 7, a breaker 100 is configured by fixing a terminal plate 3, which connects a fixed contact metal plate 4 and a resilient arm plate 6, to a plastic case 1, and incorporating a bimetal 8 that deforms the resilient arm plate 6 and a heater 9 that heats the bimetal 8 under the resilient arm plate 6. The breaker 100 in Fig. 6 incorporates a heater 9 that heats the bimetal 8, making it ideal for applications in which the heater 9 heats the bimetal 8 to maintain a current-interrupted state. (Case 1)

[0025] The case 1 has connection terminals 3X and 4X arranged at each end 1C of the bottom surface of the case 1 in the vertical direction (V). In the case 1 shown in FIGS. 1 and 2, the connection terminal 4X is arranged at one end 1C of the bottom surface of the case 1, and the connection terminal 3X is arranged at the other end 1C of the bottom surface of the case 1. The bottom surface of the case 1 is the bottom side of the case 1 as shown in FIGS. 1 and 2, and is the surface on which the connection terminals 3X and 4X are arranged. The connection terminals 3X and 4X can be arranged on all or part of either end 1C, or on a corner 1D of the end 1C of the bottom surface of the case 1. The corner 1D indicates the range from the center to the corner of each end 1C of the bottom surface. In the case 1 shown in the figures, the connection terminals 3X and 4X are arranged at the corners 1D (four corners) of each end 1C of the bottom surface. The connection terminals 3X, 4X arranged at the corners 1D of the bottom surface of the case 1 electrically connect a pair of connection terminals 4X arranged at one end 1C in the vertical direction (V) of the case 1 to the fixed contact metal plate 4, and a pair of connection terminals 3X arranged at the other end 1C to the elastic arm plate 6 via the terminal plate 3. The case 1 in FIG. 6 is made of plastic and consists of a main case 1A and a lid case 1B. The lid case 1B is connected to the main case 1A to provide a storage space 20 inside. The fixed contact metal plate 4 and terminal plate 3 are insert-molded into the main case 1A to secure them in place, and the lid case 1B is fixed to the top surface of the case 1. The main case 1A has a first outer wall 11A and a second outer wall 11B protruding from both ends, providing a storage space 20 between the first outer wall 11A and the second outer wall 11B. In the case 1 of Fig. 6, a fixed contact metal plate 4 is disposed on the bottom surface of a storage space 20 provided in a main case 1A, and the top surface of the storage space 20 is closed by a cover case 1B. In the case 1 of Figs. 1 and 2, the longitudinal direction is the vertical direction (V) and the lateral direction is the width direction (W). (Main case 1A)

[0026] The main body case 1A has an outer peripheral wall 10 around the storage space 20. The outer peripheral wall 10 has an outer wall 11 consisting of a first outer wall 11A and a second outer wall 11B, and an opposing wall 12 connecting both ends of the first outer wall 11A and the second outer wall 11B, with the opposing wall 12 and the outer wall 11 being provided around the storage space 20. The main body case 1A surrounds the storage space 20 with the outer peripheral wall 10, and the bottom and top of the outer peripheral wall 10 are closed. The bottom of the storage space 20 is closed by a bottom portion 13 and a fixed contact metal plate 4 that are molded integrally with the main body case 1A, and the top is closed by a lid case 1B that is connected to the main body case 1A, making the storage space 20 a closed hollow space.

[0027] The fixed contact metal plate 4 and the terminal plate 3 are fixed to the main body case 1A by insert molding. The main body case 1A is fixed by embedding a portion of the fixed contact metal plate 4 in the first outer wall 11A. In Figures 6 and 7, the fixed contact metal plate 4 is fixed to the main body case 1A by insert molding so that the middle portion 4B is embedded halfway in the first outer wall 11A. The fixed contact metal plate 4 is fixed to the main body case 1A in a state where it penetrates the first outer wall 11A, and the fixed contacts 5 are provided on the portion exposed inside the storage space 20, and the portion drawn out to the outside serves as the connection terminal 4X.

[0028] The terminal board 3 is fixed to the main case 1A by insert molding. The terminal board 3 is formed by cutting a single metal plate and then bending it to form a shape in which a pair of connection terminals 3X are connected to the side edges of the lower weld plate 3A via raised portions 3B. In the main case 1A, the raised portions 3B of the terminal board 3 are embedded in the plastic of the case 1, leaving the lower weld plate 3A exposed within the storage space 20, with the pair of connection terminals 3X located on both sides of the bottom surface 13 of the case 1. The lower weld plate 3A exposed within the storage space 20 is laminated with the upper weld plate 6B of the elastic arm plate 6, and the two are joined in a state of close contact and electrically connected by laser welds 30.

[0029] The entire surface of the lower weld plate 3A of the terminal board 3 can be exposed to the storage space 20, with the upper weld plate 6B of the elastic arm plate 6 laminated on the exposed portion 3a and connected by laser welded portion 30, or a portion of the lower weld plate 3A, for example both ends, can be embedded in the plastic of the case 1. In this state, the terminal board 3 fixed to the main case 1A by insert molding can be connected by laminating the upper weld plate 6B on the exposed portion 3a of the lower weld plate 3A and laser welding it. With both ends of the lower weld plate 3A embedded in the case 1, the terminal board 3 fixed to the case 1 can be fixed in a fixed position in the case 1 without any misalignment, and the upper weld plate 6B can be laminated on the lower weld plate 3A exposed to the storage space 20 and laser welded.

[0030] The fixed contact metal plate 4 is insert-molded into the main case 1A and positioned in a fixed position, so the fixed contact 5 is positioned in a fixed position in the case 1 via the fixed contact metal plate 4. The terminal board 3 is also insert-molded into the main case 1A and positioned in a fixed position, and a resilient arm plate 6 is connected to the terminal board 3, so the movable contact 7 is positioned in a fixed position in the case 1 via the resilient arm plate 6. The main case 1A, which positions the fixed contact 5 and the movable contact 7 in a fixed position with this structure, has the advantage of preventing misalignment of the contact positions between the movable contact 7 and the fixed contact 5. The movable contact 7 is connected to the main case 1A via the resiliently deformable resilient arm plate 6, so that the resilient arm plate 6 and the terminal board 3 are reliably connected, preventing misalignment relative to the fixed contact 5. Relative misalignment of the connection position between the terminal board 3, which is fixed in a fixed position in the main case 1A, and the resilient arm plate 6 causes misalignment of the movable contact 7, which in turn causes misalignment of the movable contact 7 and the fixed contact 5. The relative positional deviation between the fixed contact 5 and the movable contact 7 causes an increase in the contact resistance between the reciprocating movable contact 7 and the fixed contact 5 .

[0031] 6, the upper welding plate 6B of the elastic arm plate 6 is connected to the main case 1A by a fitting structure and placed in a fixed position. This structure of the main case 1A has the advantage that the elastic arm plate 6 is placed in a fixed position by the fitting structure, and the upper welding plate 6B is laser-welded to the lower welding plate 3A of the terminal board 3, so that it can be placed in the fixed position without misalignment.

[0032] Furthermore, the main body case 1A shown in the cross-sectional view of Figure 6 is provided with a storage recess 29 in which the heater 9 is placed in the storage space 20. The storage recess 29 is located in the center of the storage space 20, and its bottom is closed by the tip 4A of the fixed contact metal plate 4. The storage recess 29 has an inner shape slightly larger than the outer shape of the heater 9 so that the heater 9 can be inserted therein. The storage recess 29 also has a protrusion 19 along its outer periphery. The heater 9 inserted into the storage recess 29 protrudes slightly from the upper surface of the protrusion 19, and the curved bimetal 8 rests on the upper surface in a thermally coupled state.

[0033] The bottom of the storage recess 29 of the storage space 20 is closed by the fixed contact metal plate 4, and the outer bottom surface of the storage recess 29 is closed by the plastic of the main case 1A. The main case 1A is fixed to the main case 1A by insert molding the fixed contact metal plate 4 into the plastic bottom 13 that closes the bottom of the storage space 20 on the outside of the storage recess 29. (Lid case 1B)

[0034] As shown in FIG. 6 , the lid case 1B is disposed on the opening side of the case body 1A, covering the upper portion of the elastic arm plate 6. The lid case 1B shown in the figure is made of plastic, and is fixed to the case body 1A by fixing its outer peripheral edge to the upper surface of the outer peripheral wall 10 of the case body 1A. As shown in FIGS. 6 and 7 , the lid case 1B has an outer peripheral wall 22 that protrudes toward the case body 1A at its outer peripheral edge facing the outer peripheral wall 10 of the case body 1A. The inner side of this outer peripheral wall 22 has a downwardly opening recessed shape that serves as a storage section 23 for storing the elastic arm plate 6, which is elastically deformed when pressed by the bimetal 8. The outer peripheral wall 22 of the lid case 1B is fixed to the first outer wall 11A and the second outer wall 11B provided at both ends of the case body 1A, and is further fixed to the opposing wall 12. The plastic lid case 1B is connected to the case body 1A by ultrasonic welding.

[0035] The case 1 shown in Figures 6 and 7 has mating connecting protrusions 17 and connecting recesses 18 to accurately position and connect the lid case 1B and the main case 1A. The lid case 1B shown in Figure 6 has connecting protrusions 17 that protrude from the underside of the outer peripheral wall 22 toward the main case 1A on both sides of the end of the main case 1A facing the first outer wall 11A. As shown in Figure 6, the main case 1A has connecting recesses 18 that guide the connecting protrusions 17 on the upper surface of the outer peripheral wall 10 opposite these connecting protrusions 17. Furthermore, the lid case 1B shown in Figure 6 has mating protrusions 16 that fit into the open end of recesses 21 on the second outer wall 11B side of the main case 1A and are positioned on the upper surface of the laminated portion 40 of the elastic arm plate 6. The outer shape of this mating convex portion 16 is similar to the planar shape of the recess 21, and is shaped to fit into the step recess 24 formed on the upper surface side of the upper welding plate 6B of the elastic arm plate 6 inserted into the recess 21.

[0036] In the above case 1, the connecting protrusions 17 on both sides of the lid case 1B are guided into the connecting recesses 18 of the main case 1A at the end of the main case 1A on the first outer wall 11A side, and the fitting protrusions 16 of the lid case 1B are guided into the stepped recesses 24 formed on the upper surface of the laminated portion 40 of the elastic arm plate 6 at the end of the main case 1A on the second outer wall 11B side, so that the lid case 1B is connected to the main case 1A in an accurate position (fixed contact metal plate 4).

[0037] The fixed contact metal plate 4 is fixed to the main body case 1A by insert molding. The fixed contact metal plate 4 in Fig. 6 has a front end portion 4A that closes the opening of the bottom 13 of the storage space 20, a rear end portion 4C having a connection terminal 4X, and an intermediate portion 4B between the front end portion 4A and the rear end portion 4C. The fixed contact metal plate 4 shown in the cross-sectional view of Fig. 6 closes the opening of the bottom 13 of the storage space 20 with the front end portion 4A, and is fixed to the main body case 1A by insert molding so that parts of the intermediate portion 4B and the rear end portion 4C are embedded from the bottom 13 of the storage space 20 into the first outer wall 11A of the main body case 1A. The fixed contact metal plate 4 in Figures 6 and 7 has a step portion 4D so that the portion embedded in the first outer wall 11A is higher than the portion that blocks the opening of the bottom 13 of the storage space 20, and the step portion 4D is embedded in the bottom 13 of the main body case 1A, with a portion of the step portion 4D exposed on the upper surface of the bottom 13, and this exposed portion serves as the fixed contact 5.

[0038] The fixed contact metal plate 4 can be formed into the fixed contact 5 by press-fitting a silver inlay material into the metal plate. The metal plate of the fixed contact 5 is made of copper, a copper alloy, or nickel, or a nickel alloy. The inlay material can be made thicker to extend the contact life, so the thickness is set to 200 μm. However, the surface of the fixed contact metal plate 4 can be silver-plated, and the silver-plated layer can be used as the fixed contact 5. The silver-plated layer of the fixed contact 5 is thicker than the silver-plated layer of the movable contact 7, for example, 6 μm. However, the film thickness of the silver-plated layer of the fixed contact 5 can be set to 5 μm to 100 μm, preferably 3 μm to 50 μm, and can be thicker than the movable contact 7. By making the silver-plated layer of the fixed contact 5 thicker, the fixed contact 5 can be connected to a polarity that is easily damaged, thereby extending the connection life.

[0039] The fixed contact metal plate 4 has a connection terminal 4X on the rear end 4C side. The fixed contact metal plate 4 in FIGS. 4 to 7 has a pair of connection terminals 4X spaced apart from each other. As shown in FIGS. 1 and 2 , the pair of connection terminals 4X are located at corners of the bottom surface of the case 1. The connection terminal 4X of the fixed contact metal plate 4 is bent so that the rear end 4C extending outward from the case 1 is positioned approximately flush with the bottom surface of the case 1, i.e., the bottom surface of the main case 1A, so that it can be fixed to the surface of a circuit board by soldering such as reflow soldering. This breaker 100 is subjected to reflow soldering by heating with the connection terminal 4X positioned on the solder surface of the circuit board. However, the breaker can also be configured such that the exposed portion of the fixed contact metal plate 4 exposed from the bottom surface of the insulating case serves as an exposed terminal 44, and this exposed terminal 44 can be reflow soldered to the solder surface of the circuit board. This breaker can be fixed by soldering the exposed terminal 44 of the fixed contact metal plate 4 to the surface of a circuit board or the like, without necessarily having to pull out the connection terminal 4X from the case 1 to the outside. (Elastic arm plate 6)

[0040] The elastic arm plate 6 shown in Figures 3, 5 to 7 has a movable contact 7 at its tip 6D, which faces the fixed contact 5, and an upper weld plate 6B at its rear end 6E. The upper weld plate 6B is laminated on the lower weld plate 3A of the terminal board 3 and fixed to the terminal board 3 by a laser weld 30, with the movable portion 6A in the middle being disposed inside the storage space 20. The elastic arm plate 6 is made of an elastically deformable conductive metal plate. A Cu-Cr-Ag-Si alloy can be used for the metal plate of the elastic arm plate 6. The Cu-Cr-Ag-Si alloy contains Cu as a base material, and 0.01 to 5 wt%, preferably 0.01 to 2.5 wt%, of Cr, 0.01 to 5 wt%, preferably 0.01 to 2.5 wt%, of Ag, and 0.01 to 5 wt%, preferably 0.01 to 2.5 wt%, of Si. The elastic arm plate 6 may also be made of an elastic metal plate, such as a copper alloy containing Ni, P, Zn, and Fe, a copper alloy containing Fe, P, and Zn, a copper alloy containing Cr and Mg with an IACS of 75% to 95%, a copper alloy containing Zr with an IACS of 80% to 95%, or a copper alloy containing Sn with an IACS of 80% to 95%. However, IACS (international annealed copper standard) is an internationally adopted standard for electrical resistance or electrical conductivity, and is based on annealed standard soft copper (volume resistivity: 1.7241 x 10 －２ This is a notation that defines the conductivity as 100%.

[0041] Furthermore, the elastic arm plate 6 has a movable contact 7 on the tip 6D of the movable part 6A, facing the fixed contact 5. The movable contact 7 of the elastic arm plate 6 has a silver-plated layer on the area facing the fixed contact 5, thereby reducing contact resistance with the fixed contact 5. When the bimetal 8 is not thermally deformed, the movable contact 7 of the elastic arm plate 6 contacts the fixed contact 5, resulting in an ON state. When the bimetal 8 is thermally deformed, the movable part 6A pressed by the bimetal 8 elastically deforms, causing the movable contact 7 to separate from the fixed contact 5, resulting in an OFF state. The non-energized type breaker 100 shown in Figure 6 has a pressing protrusion 25 protruding from the inner surface of the lid case 1B that presses downward on the rear end 6E of the movable part 6A, so that the movable contact 7 can reliably contact the fixed contact 5 when the bimetal 8 is not thermally deformed. When the rear end 6E side of the movable part 6A of this elastic arm plate 6 is pressed downward by the pressing protrusion 25, the tip end 6D of the movable part 6A is forced downward, and the movable contact 7 at the tip is reliably brought into contact with the fixed contact 5.

[0042] Furthermore, the breaker 100 can be provided with a deformation limiting protrusion 26 on the cover case 1B. The deformation limiting protrusion 26 is located in a position that presses the tip 6D of the movable part 6A, i.e., the movable contact 7 side, downward, and by protruding toward the movable part 6A, it can limit the amount of deformation of the movable part 6A of the elastic arm plate 6 when pressed by the bimetal 8 in the OFF state, in which the bimetal 8 thermally deforms and the movable contact 7 separates from the fixed contact 5. In this breaker 100, the deformation limiting protrusion 26 presses the tip 6D of the movable part 6A downward, i.e., toward the fixed contact 5, thereby limiting the amount of deformation of the movable part 6A when pressed up by the inverted bimetal 8. Therefore, the breaker 100 with this structure has the advantage of preventing the inverted bimetal 8 from pushing up the movable part 6A of the elastic arm plate 6 beyond its elastic limit and reducing its springiness, and can press the movable contact 7 against the fixed contact 5 with a predetermined contact pressure after resetting, thereby maintaining low contact resistance.

[0043] Furthermore, the elastic arm plate 6 has a protrusion 6C on its underside, which allows both ends of the bimetal 8 to come into contact with and press against each other. The protrusion 6C shown in FIG. 6 has an arc-shaped outer shape, allowing both ends of the bimetal 8 to reliably come into contact and press against each other without sliding laterally. The elastic arm plate 6 shown in the figure has multiple protrusions 6C on its underside facing both ends of the bimetal 8. This structure allows even wide bimetals 8 to reliably come into contact and press against each other. (Terminal plate 3)

[0044] The terminal board 3 shown in Figures 3 to 7 is a highly conductive metal plate fixed to the case body 1A. The elastic arm plate 6, connected by laser welds 30, is positioned in a fixed position on the case body 1A. The terminal board 3 is insert-molded and partially embedded in the case body 1A to be fixed in place. The terminal board 3 includes a lower weld plate 3A extending in the width direction of the case 1, a raised portion 3B connected to the lower weld plate 3A, and a connection terminal 3X connected to the raised portion 3B. The terminal board 3 includes the lower weld plate 3A extending toward the inside of the case 1 on the upper end of the raised portion 3B, and a connection terminal 3X extending toward the outer edge of the case 1 on the lower end of the raised portion 3B. As shown in Figure 3, the raised portion 3B is positioned approximately vertically, and the lower weld plate 3A and the connection terminal 3X are positioned horizontally. The terminal board 3 in Figure 3 has a pair of connection terminals 3X connected to both ends of the side edges of the lower weld plate 3A via the raised portion 3B. A pair of connection terminals 3X in Fig. 3 are connected to both ends of a rising portion 3B extending in the width direction of the case 1, and are arranged in corners 1D of the bottom surface of the case 1. The pair of connection terminals 3X are arranged at one end 1C of the bottom surface of the case 1, extending in the vertical direction (V) of the case 1 from the connection portion with the rising portion 3B toward the tip of the connection terminals 3X. The lower weld plate 3A in Fig. 6 has its upper surface exposed to the storage space 20 of the case 1, and an upper weld plate 6B of the elastic arm plate 6 is connected to it. The upper weld plate 6B of the elastic arm plate 6 is laminated on the surface of the exposed portion 3a of the lower weld plate 3A, and they are connected by a laser weld 30.

[0045] The lower weld plate 3A and the upper weld plate 6B are laser welded together in the following steps: (1) The upper weld plate 6B of the elastic arm plate 6 is laminated onto the surface of the lower weld plate 3A. (2) The upper weld plate 6B is pressed against the lower weld plate 3A, so that the upper weld plate 6B is tightly attached to the surface of the lower weld plate 3A without any gaps. (3) With the upper weld plate 6B in tight contact with the lower weld plate 3A, a laser beam 50 is irradiated onto the surface of the upper weld plate 6B, and both the upper weld plate 6B and the lower weld plate 3A are melted and welded together by the laser beam 50.

[0046] The lower weld plate 3A of the terminal board 3 connects a pair of connection terminals 3X via rising portions 3B to both ends of the side edge extending in the width direction (W) of the case 1. The pair of connection terminals 3X connected to both ends of the lower weld plate 3A via the rising portions 3B are arranged at one end 1C (corner portion 1D) of the bottom surface of the case 1. The rising portions 3B penetrate the case 1, and the pair of connection terminals 3X are arranged on the bottom surface of the case 1. The rising portions 3B are embedded in the plastic of the case 1 in an orientation parallel to the width direction (W) of the case 1, so that the lower weld plate 3A is arranged in the storage space 20 and the connection terminals 3X are arranged on the bottom surface of the case 1.

[0047] The laser welded portion 30 melts and reliably welds both the upper weld plate 6B and the lower weld plate 3A by stacking two metal plates without any gaps and irradiating them with a laser beam 50. When laser welding, it is important to bring the two metal plates into close contact with each other without any gaps at the timing of irradiating the laser beam 50. Any gaps that form between the two metal plates when irradiating the laser beam 50 can hinder stable welding of the two metal plates. To ensure that the upper weld plate 6B can be tightly attached to the lower weld plate 3A without any gaps when irradiating the laser beam 50, the width (W1) of the lower weld plate 3A is set to be equal to or greater than the width (W2) of the upper weld plate 6B, and the upper weld plate 6B is positioned inside the lower weld plate 3A, allowing the entire surface of the upper weld plate 6B to be in close contact with the surface of the lower weld plate 3A. The upper welding plate 6B, which is stacked inside the lower welding plate 3A, can be pressed from the surface to adhere its entire surface to the surface of the lower welding plate 3A. In this state, a laser beam 50 is irradiated onto the surface of the upper welding plate 6B, melting both the upper welding plate 6B and the lower welding plate 3A, which are in close contact with each other. In this state, the upper welding plate 6B and the lower welding plate 3A are securely welded together, and the elastic arm plate 6 and the terminal plate 3 are securely connected in an electrically connected state.

[0048] Furthermore, the breaker 100 shown in FIG. 1 and other figures has a compact external shape while reliably securing the terminal board 3 to the case 1 and positioning the raised portion 3B in a specific location to reliably laser-weld the upper welding plate 6B to the lower welding plate 3A. The raised portion 3B is connected to a side edge of the lower welding plate 3A extending in the width direction (W) of the case 1 (the left side edge of the lower welding plate 3A in FIG. 3) and is embedded in the case 1 as shown in FIG. 6 to position the terminal board 3 in a fixed position in the case 1. The raised portion 3B embedded in the plastic of the case 1 positions the lower welding plate 3A, which is connected to its upper end in FIG. 3, in the storage space 20 of the case 1, and positions a pair of connection terminals 3X in corners 1D on both sides of the bottom surface of the case 1. The pair of connection terminals 3X positioned in the corners 1D of the bottom surface of the case 1 are fixed to one end 1C of the bottom surface in an orientation extending in the vertical direction (V) of the case 1 from the connection point with the raised portion 3B toward its tip.

[0049] In the terminal board 3 shown in Figure 3, the angle (α) between the rising portion 3B and the lower weld plate 3A is approximately a right angle (within 90 degrees ± 15 degrees), and the angle (β) between the rising portion 3B and the connection terminal 3X is also approximately a right angle (within 90 degrees ± 15 degrees), and the rising portion 3B is embedded in the plastic of the case 1 in an approximately vertical position. However, as shown in Figure 11, the angle (α) between the rising portion 3B and the lower weld plate 3A and the angle (β) between the rising portion 3B and the connection terminal 3X can be acute, which has the advantage of allowing the connection terminal 3X to be long while maintaining a compact external shape. This structure also has the advantage of allowing the longer rising portion 3B to be embedded in the plastic of the case 1 in an inclined position, thereby more firmly fixing the terminal board 3 to the case 1. The angle (α) between the rising portion 3B and the lower weld plate 3A and the angle (β) between the rising portion 3B and the connection terminal 3X can also be obtuse. The terminal board 3 can be formed by cutting a single metal plate and then bending it to have the lower welding plate 3A, the rising portion 3B, and the connection terminal 3X.

[0050] The structure in which the connection terminal 3X is disposed on the bottom surface of the case 1 via the rising portion 3B allows the connection terminal 3X to be disposed on approximately the same plane as the bottom surface of the case 1 as an SMD (surface mount) breaker, and can be connected and fixed to the solder surface of a circuit board by a method such as reflow soldering (laser welded portion 30).

[0051] The laser welded portion 30 reliably welds the upper weld plate 6B and the lower weld plate 3A, positioning the movable contact 7 and fixed contact 5 in fixed positions and preventing misalignment of the contact positions. Since a microbreaker uses an extremely thin metal plate for the elastic arm plate 6, the contact pressure of the contacts is quite small, at 10 g or less, so it is particularly important to maintain low contact resistance. An increase in contact resistance increases Joule heat due to current, causing damage to the contacts and an accelerated increase in contact resistance, which can also cause various problems, such as thermal deformation of the plastic case 1.

[0052] The laser weld 30 is preferably formed by irradiating a fiber laser beam to melt both the upper weld plate 6B and the lower weld plate 3A of the elastic arm plate 6, thereby ensuring reliable welding. The upper weld plate 6B and the lower weld plate 3A are stacked in close contact with each other without any gaps, and then irradiated with a laser beam 50 to ensure reliable welding. Gaps that occur between the upper weld plate 6B and the lower weld plate 3A at the time of irradiating the laser beam 50 impair the stability of the welded state of the laser weld 30. To ensure close contact between the upper weld plate 6B and the lower weld plate 3A without any gaps, the surface of the upper weld plate 6B of the elastic arm plate 6 is pressed with a pusher 51 to perform laser welding, as shown in FIG. 12 . As shown in the figure, the pusher 51 presses the vicinity of the laser weld 30 where the laser beam 50 is irradiated, for example, on both sides or around the laser weld 30, thereby ensuring close contact of the upper weld plate 6B with the surface of the lower weld plate 3A.

[0053] The upper welding plate 6B and the lower welding plate 3A are arranged in close contact with each other. The width (W1) of the lower welding plate 3A is made larger than the width (W2) of the upper welding plate 6B, so that the entire upper welding plate 6B can be in close contact with the surface of the lower welding plate 3A.

[0054] The case 1 shown in the cross-sectional view of FIG. 12 has a bottom plate 15 on the back surface of the lower weld plate 3A of the terminal board 3 so that the upper weld plate 6B of the elastic arm plate 6 comes into close contact with the surface of the lower weld plate 3A of the terminal board 3 when pressed by the pusher 51. The bottom plate 15 is molded integrally with the main case 1A in a state in which it comes into close contact with the terminal board 3. In this breaker 100, when the elastic arm plate 6 is pressed by the pusher 51, the bottom plate 15 supports the underside of the terminal board 3, bringing the elastic arm plate 6 into close contact with the surface of the terminal board 3. In this breaker 100, during the process of welding the elastic arm plate 6 to the terminal board 3, the case 1 is placed on a flat base plate 52, and the elastic arm plate 6 is pressed to come into close contact with the terminal board 3. When the elastic arm plate 6 is pressed by the pusher 51, the terminal board 3 is supported by the base plate 52 via the bottom plate 15. Therefore, when the pusher 51 presses the elastic arm plate 6, the stacked elastic arm plate 6 and terminal plate 3 are sandwiched between the pusher 51 and the bottom plate 15 and tightly adhere to each other. The breaker 100 with this structure has the advantage of being able to be mass-produced efficiently, since the main case 1A is placed on the flat base plate 52, and the elastic arm plate 6 is pressed against the terminal plate 3 to tightly adhere to it and laser weld it. This is because there is no need to precisely adjust the position of the main case 1A on the base plate 52. Furthermore, this structure has the advantage that the thermoplastic bottom plate 15 acts as a buffer layer when the pusher 51 presses the elastic arm plate 6. Therefore, the bottom plate 15 absorbs any error in the pressing position of the pusher 51, allowing the pressing force between the elastic arm plate 6 and the terminal plate 3 to be optimally adjusted.

[0055] 12 has an opening 15A formed in bottom plate 15, and a protruding support rib 53 formed on base plate 52 that directly supports the underside of terminal board 3. Opening 15A in bottom plate 15 is located on the underside of lower welding plate 3A of terminal board 3. This case body 1A is set in a fixed position on base plate 52 with support rib 53 guided into opening 15A. With support rib 53 supporting the underside of terminal board 3, elastic arm plate 6 stacked on terminal board 3 is pressed by pusher 51, and elastic arm plate 6 and terminal board 3 are tightly attached and laser welded together.

[0056] The elastic arm plate 6, which has the movable contact 7 fixed to its tip, connects the upper weld plate 6B to the terminal plate 3 by laser welding. Laser welding involves locally irradiating a laser beam 50 to melt and spot-weld the elastic arm plate 6 and the terminal plate 3. The elastic arm plate 6, connected to the terminal plate 3 by spot welding, is pushed by the reversing bimetal 8 to switch to the OFF state, and then the bimetal 8 returns to its original position to switch to the ON state. The elastic arm plate 6 switches to the OFF state by moving the movable contact 7 away from the fixed contact 5 and to the ON state by contacting the fixed contact 5. However, since the movable contact 7 is located at its tip and the upper weld plate 6B is fixed to the terminal plate 3, even a slight misalignment of the upper weld plate 6B increases the misalignment of the movable contact 7 at its tip. Therefore, even a slight misalignment of the upper weld plate 6B of the elastic arm plate 6 causes a shift in the contact position between the movable contact 7 and the fixed contact 5. A slight misalignment of the contact position between the movable contact 7 and the fixed contact 5 causes a change in contact resistance. With the elastic arm plate 6 that is locally spot-welded, it is difficult to prevent the contact position from shifting over a long period of time when the movable contact 7 moves back and forth.

[0057] Furthermore, because laser welding is subject to various external conditions, such as temperature and surface condition, which can cause fluctuations in the weld condition, it is difficult to reliably connect the resilient arm plate 6 to the terminal plate 3 and reliably prevent misalignment of the contacts in all mass-produced breakers. Furthermore, the bimetal 8 momentarily reverses when the ambient temperature reaches a set temperature and then momentarily returns to its original state when the ambient temperature drops to its reset temperature, impacting the resilient arm plate 6. This also makes it difficult to securely fasten the resilient arm plate 6 to the terminal plate 3 for an extended period of time. In addition, in extremely small microbreakers, even a slight misalignment of the contacts increases contact resistance. This is because the contact pressure between the movable contact 7 and the fixed contact 5 is weak, and in the ON state, the movable contact 7 and the fixed contact 5 are in contact over an extremely narrow area. Furthermore, the surfaces of the breaker's movable contact 7 and fixed contact 5 are not always maintained in a uniform state, and the contact resistance in the non-contact areas, where there is no constant contact, is higher due to thin oxide films and other factors than in the areas where there is constant contact.

[0058] Microbreakers employ an activation process to reduce the contact resistance of the contacts. The contact activation process involves applying ultrasonic vibrations to the contacts while they are energized in the ON state. Contacts activated in this way only have low contact resistance when the movable contact 7 and fixed contact 5 are in contact at a specific position, so the contact resistance increases if the contact position of the contacts is shifted.

[0059] 8 to 10 show examples of laser welds 30 that fix the elastic arm plate 6 to the terminal plate 3 while preventing misalignment. The upper and lower weld plates can be connected by laser welding at the laser welds 30. The laser welds 30 can be formed by welding at one or more weld spots 32 ( FIG. 8 ), or by welding at one or more elongated linear weld lines 31 ( FIGS. 9 and 10 ), or by welding at both the linear weld line 31 and multiple weld spots 32.

[0060] The laser welded portion 30 in Figure 8 has multiple weld spots 32 spaced apart in the width direction (W), which is the short direction of the elastic arm plate 6. The laser welded portion 30 in Figure 8 has three weld spots 32 spaced apart in the width direction (W) of the elastic arm plate 6, but two or four or more weld spots 32 can also be provided. Because the laser welded portion 30 in this figure has multiple weld spots 32 spaced apart in the width direction (W) of the elastic arm plate 6, when the elastic arm plate 6 is in a state where it is elastically deformed, the region of the laminated portion 40 of the elastic arm plate 6 that extends in the width direction (W) can be tightly attached to the terminal plate 3. This prevents the contact positions of the movable contact 7 and the fixed contact 5 from shifting in the width direction (W), and stabilizes the contact pressure of the contacts. Furthermore, the multiple welding spots 32 can be arranged at intervals in the vertical direction (V), which is the lengthwise direction of the elastic arm plate 6, and the region extending in the longitudinal direction of the elastic arm plate 6 can be brought into close contact with the terminal plate 3, thereby stabilizing the contact pressure of the contacts while preventing misalignment of the contact positions between the movable contact 7 and the fixed contact 5. Furthermore, the laser welded portion 30 can have the multiple welding spots 32 arranged at intervals in the vertical direction (V) and widthwise direction (W) of the elastic arm plate 6, and the region extending in both the longitudinal and lateral directions of the elastic arm plate 6 can be brought into close contact with the terminal plate 3, reliably preventing misalignment of the contact positions between the movable contact 7 and the fixed contact 5 in both the longitudinal and lateral directions.

[0061] In the laser welded portion 30 shown in Figure 9, the linear weld line 31 is replaced with a horizontal weld line 31B extending in the width direction (W), which is the short-side direction of the elastic arm plate 6. While the horizontal weld line 31B in this figure is linear and parallel to the width direction (W) of the elastic arm plate 6, the horizontal weld line 31B can also be linear and extend in a direction inclined relative to the width direction (W) of the elastic arm plate 6, or curved. Because the horizontal weld line 31B extends in the width direction (W), which is the short-side direction of the elastic arm plate 6, when the elastic arm plate 6 elastically deforms in the width direction (W), the region of the laminated portion 40 of the elastic arm plate 6 extending in the width direction (W) can be tightly attached to the terminal plate 3. This prevents misalignment of the contact positions of the movable contact 7 and the fixed contact 5 in the width direction (W), stabilizing the contact pressure of the contacts.

[0062] In the laser welded portion 30 shown in Figure 10, the linear weld line 31 is a vertical weld line 31A extending in the vertical direction (V), which is the longitudinal direction of the elastic arm plate 6. In this figure, the vertical weld line 31A is a straight line parallel to the vertical direction (V) of the elastic arm plate 6, but the vertical weld line 31A can also be a straight line extending in a direction inclined relative to the vertical direction (V) of the elastic arm plate 6, or a curved line. Because the vertical weld line 31A in this figure extends in the vertical direction (V), which is the longitudinal direction of the elastic arm plate 6, the region of the laminated portion 40 of the elastic arm plate 6 extending in the vertical direction (V) can be tightly attached to the terminal plate 3 even when the elastic arm plate 6 is elastically deformed to bend in the vertical direction (V). This prevents misalignment of the contact positions between the movable contact 7 and the fixed contact 5, thereby achieving the advantage of stabilizing the contact pressure of the contacts.

[0063] Furthermore, the laser welded portion 30 can have weld lines 31 arranged as two or more rows of vertical weld lines 31A ( FIG. 10 ) and / or two or more rows of horizontal weld lines 31B. The rows of vertical weld lines 31A can be spaced apart in the width direction (W) of the elastic arm plate 6 (two rows in FIG. 10 ), and the rows of horizontal weld lines 31B can be spaced apart in the longitudinal direction of the elastic arm plate 6. This prevents misalignment of the contact positions of the movable contact 7 and the fixed contact 5, thereby achieving the advantage of stabilizing the contact pressure of the contacts. Furthermore, the laser welded portion 30 can have weld lines 31 extending along a ring, and can have regular or irregular shapes, such as circular, elliptical, oblong, or rectangular.

[0064] Furthermore, by combining one or more vertical weld lines 31A with one or more horizontal weld lines 31B, it is possible to create regular or irregular shapes, such as triangles, approximately squares, rectangles, polygons, ovals, wavy shapes, uneven shapes, zigzags, and unicursal shapes. Furthermore, any one or more of these can be combined. In any case, it is possible to prevent misalignment of the contact positions of the movable contact 7 and the fixed contact 5, thereby realizing the advantage of stabilizing the contact pressure of the contacts. (Contact Activation Treatment)

[0065] A microbreaker with weak contact pressure can be activated to reduce contact resistance after assembly. The contact activation process is performed by ultrasonically vibrating the contacts of the assembled breaker 100 while current is flowing. The breaker 100 causes the movable contact 7 and the fixed contact 5 to collide with each other and ultrasonically vibrate in the direction of separation. That is, the breaker 100 ultrasonically vibrates the fixed contact 5 and the movable contact 7 so that they approach each other, collide, and then move relatively away from each other. When ultrasonically vibrating, the contact current is preferably 0.1 A to 100 A under a resistive load. Increasing the contact current during ultrasonic vibration more effectively activates the contacts. In an inductive load with a coil connected in series with a resistor increases the current energy stored in the coil when the current is interrupted, allowing the contact current to be reduced to activate the contacts. This is because the discharge current of the contacts increases to consume the current energy stored in the coil. Therefore, the contact current is set to an optimal value taking into account the resistive load and inductive load. Furthermore, the breaker 100 has the characteristic that when the current through the contacts is increased, it generates heat through Joule heating and switches itself to the OFF state. To activate the contacts with ultrasonic vibration, it is necessary to maintain the movable contact 7 in an ON state in contact with the fixed contact 5. Therefore, when a large current is passed through the contacts to generate ultrasonic vibration, the ultrasonic vibration time is shortened and the contacts are ultrasonically vibrated while in the ON state. Therefore, when a large current is passed through the contacts to generate ultrasonic vibration, the ultrasonic vibration time is shortened.

[0066] The time for which the contacts are ultrasonically vibrated while current is applied is set to 0.1 milliseconds to 1 second. The contacts can be activated more effectively by extending the ultrasonic vibration time, but if it is too long, the silver plating layer of the contacts will be damaged, so the time is set so that the contacts can be activated without damaging the silver plating layer. Furthermore, contact activation by ultrasonic vibration is also affected by the contact current, type of load, and amplitude of ultrasonic vibration; when the contact current and amplitude are large, the contacts are activated more effectively in a short time. Therefore, the ultrasonic vibration time is set to an optimal value within the above range, taking into account the contact current and amplitude of ultrasonic vibration.

[0067] The frequency at which the contacts are ultrasonically vibrated is 20 KHz to 6 GHz, preferably 20 KHz to 1 GHz. Increasing the frequency of the ultrasonic vibration increases the number of collisions and separations between the movable contact 7 and the fixed contact 5 per unit time. However, if the frequency of the ultrasonic vibration is too high, the distance between the movable contact 7 and the fixed contact 5 becomes narrower, reducing activation by discharge. Conversely, if the frequency is too low, the number of collisions decreases, reducing activation. Therefore, the frequency of the ultrasonic vibration is set to an optimal value, taking into account the thickness and length of the elastic arm plate 6, as well as the resonant frequency of the elastic arm plate 6.

[0068] Furthermore, the amplitude of ultrasonic vibration of the breaker 100 is set to 0.01 μm to 100 μm. Increasing the amplitude of ultrasonic vibration increases the kinetic energy of the movable contact 7 when it collides with the fixed contact 5, and also increases the distance at which the movable contact 7 is separated from the fixed contact 5. The amplitude of ultrasonic vibration of the breaker 100 affects the distance at which the movable contact 7 is separated from the fixed contact 5. However, by resonating the elastic arm plate 6, the distance at which the movable contact 7 is separated from the fixed contact 5 can be made greater than the amplitude of ultrasonic vibration of the breaker 100. Therefore, by setting the frequency at which the ultrasonic vibration of the breaker 100 is set to the resonant frequency of the elastic arm plate 6, or in the vicinity thereof, or an integer multiple of the resonant frequency, or an integer fraction of the resonant frequency, the movable contact 7 can be separated from the fixed contact 5 by a sufficient distance, thereby enabling effective activation.

[0069] In order to increase the amplitude of ultrasonic vibration of the breaker 100, it is necessary to increase the output of the ultrasonic vibrator or ultrasonic horn that contacts and ultrasonically vibrates the breaker 100. If a high-output ultrasonic vibrator or ultrasonic horn is pressed against the case 1 of the breaker 100 to cause ultrasonic vibration, problems such as deformation of the contact point with the ultrasonic vibrator due to heat generated by the ultrasonic vibration can occur, so the amplitude of ultrasonic vibration of the breaker 100 is set small within a range that still activates the contact points. (Heater 9)

[0070] When energized, the heater 9 generates heat and heats the bimetal 8. The heater 9 is a thick PTC heater with oval or rectangular opposing surfaces and electrodes on its top and bottom. However, the heater does not necessarily have to be a PTC heater; any heater that can heat the bimetal 8 when energized can be used. The heater 9, which has electrodes on both its top and bottom surfaces, has its bottom surface in contact with the fixed contact metal plate 4 and its top surface in contact with the elastic arm plate 6 via the bimetal 8. When the movable contact 7 of the elastic arm plate 6 is in contact with the fixed contact 5 in the ON state, the elastic arm plate 6 and the bimetal 8 are not in contact and no current is passed through the heater 9. When the movable contact 7 of the elastic arm plate 6 is separated from the fixed contact 5 in the OFF state, current is passed through the bimetal 8 in contact with the elastic arm plate 6 and the fixed contact metal plate 4, generating heat and heating the bimetal 8. The heated bimetal 8 maintains the movable contact 7 separated from the fixed contact 5 in the OFF state. This non-energized type breaker 100 can be used safely with battery packs because it maintains the movable contact 7 in the OFF state when switched to the OFF state. This is because, after the battery pack is used in an abnormal state and the temperature rises above the set temperature and the non-energized type breaker 100 is switched OFF, electricity continues to flow from the batteries in the battery pack to the heater 9, heating the bimetal 8, so the breaker 100 does not return to the ON state and can maintain the current interruption state until the battery is discharged.

[0071] However, the breaker is not necessarily limited to a structure with a built-in heater. In a breaker without a built-in heater, when the bimetal 8 exceeds the set temperature and deforms, deforming the elastic arm plate 6 and switching the contacts to the OFF state, the bimetal 8 is not heated to maintain the breaker in the OFF state, and when the bimetal 8 drops to a predetermined temperature, the bimetal 8 and elastic arm plate 6 return to their original positions and the breaker is switched to the ON state. (Bimetal 8)

[0072] The bimetal 8 is made of laminated metals with different thermal expansion coefficients so that it deforms when heated. The bimetal 8 is disposed between the heater 9 and the elastic arm plate 6, and when heated, it deforms and reverses, separating the movable contact 7 from the fixed contact 5 and switching the breaker 100 to the OFF state. The bimetal 8 has a shape that is convex at the center. When not thermally deformed, i.e., when the movable contact 7 is in contact with the fixed contact 5, the bimetal 8 assumes a position in which the central protrusion protrudes toward the elastic arm plate 6, as shown in FIG. 6 . When the bimetal 8 deforms and reverses, the central protrusion protrudes toward the heater 9. When the bimetal 8 deforms and reverses, the central protrusion contacts the heater 9 and both end portions contact and press against the elastic arm plate 6, pushing up the movable portion 6A of the elastic arm plate 6 and separating the movable contact 7 from the fixed contact 5, switching the breaker 100 to the OFF state.

[0073] As shown in Fig. 6, the breaker 100 is fixed to a circuit board by soldering the connection terminals 3X of the terminal board 3 and the connection terminals 4X of the fixed contact metal plate 4, which are extended to the outside from both ends of the case 1. The breaker 100 is placed on the circuit board and soldered with the bottom of the case 1, i.e., the bottom of the main case 1A, facing the top surface of the circuit board. The breaker 100 is reflow soldered by heating with the connection terminals 3X and 4X provided on both ends of the case 1 positioned on a solder surface provided on the surface of the circuit board. The breaker 100 is connected to the solder surface of the circuit board via the connection terminals 3X and 4X and is fixed in a fixed position on the circuit board.

[0074] Furthermore, the breaker 100 can be fixed to a circuit board by soldering the connection terminal 3X of the terminal board 3 extending from one end of the case 1 to the outside and the exposed terminal 44 of the fixed contact metal plate 4 exposed from the bottom surface of the main case 1A. Since the exposed terminal 44 of the fixed contact metal plate 4 is connected to the circuit board, the connection terminal 4X can be shortened. The breaker 100 is also placed and soldered to the top surface of the circuit board, with the bottom surface of the case 1, i.e., the bottom surface of the main case 1A, facing the top surface of the circuit board. The breaker 100 is reflow soldered by heating with the connection terminal 3X provided at one end of the case 1 and the exposed terminal 44 exposed from the bottom surface of the main case 1A positioned on the solder surface of the circuit board. The breaker 100 is connected to the solder surface of the circuit board via the connection terminal 3X and the exposed terminal 44 and fixed in place on the circuit board. (Embodiment 2)

[0075] In the above-described breaker 100, a pair of connection terminals 4X connected to the fixed contact metal plate 4 and a pair of connection terminals 3X connected to the terminal plate 3 connected to the elastic arm plate 6 are located in the corners 1D of each end 1C of the bottom surface of the case 1, i.e., near both ends in the width direction (W) of the case 1. However, as shown in the breaker 200 of Figure 13, the connection terminals 3X and 4X can each be located as a single connection terminal at each end 1C of the bottom surface of the case 1. By using each of the connection terminals 3X and 4X as a single connection terminal, a larger contact area can be ensured than with a pair of connection terminals. In the breaker 200, one connection terminal 4X and one connection terminal 3X are located at each end 1C of the bottom surface of the case 1, with one connection terminal 4X connected to the fixed contact metal plate 4 and the other connection terminal 3X provided on the terminal plate 3 connected to the elastic arm plate 6. As shown in Figures 14 to 17, the breaker 200 has a connection terminal 3X connected to the elastic arm plate 6, which is the same width as the width of the lower weld plate 3A, and a connection terminal 4X connected to the fixed contact metal plate 4, which is also the same width as the elastic arm plate 6. The terminal board 3 of the breaker 200 has a lower weld plate 3A to which an upper weld plate 6B is welded and fixed, a rising portion 3B connected to the side edge of the lower weld plate 3A, and a connection terminal 3X connected to the lower end of the rising portion 3B. In the terminal board 3 of Figure 14, the lower weld plate 3A, the rising portion 3B, and the connection terminal 3X all extend in the width direction (W) of the case 1 and have the same width, but any one or more of them may have different widths. The breaker 200 is similar to the breaker 100 except that the connection terminals 3X and 4X are each a single connection terminal, and the above description of the breaker 100 applies to the breaker 200.

[0076] The present invention can be suitably used as a breaker that is optimal for SMD (surface mount device) by reducing the external size while reliably connecting the elastic arm plate and the terminal plate and arranging them in fixed positions in the case.

[0077] DESCRIPTION OF SYMBOLS 100, 200, 800, 900... Breaker 1... Case 1A... Main body case 1B... Cover case 1C... End 1D... Corner 3... Terminal board 3a... Exposed portion 3A... Lower welding plate 3B... Rising portion 3X... Connection terminal 4... Fixed contact metal plate 4X... Connection terminal 4A... Tip portion 4B... Middle portion 4C... Rear end portion 4D... Step portion 5... Fixed contact 6... Elastic arm plate 6A... Movable portion 6B... Upper welding plate 6C... Protruding portion 6D... Tip portion 6E... Rear end portion 7... Movable contact 8... Bimetal 9... Heater 10... Outer wall 11... Outer wall 11A... First outer wall 11B... Second outer wall 12... Opposing wall 13... Bottom 15... Bottom plate 15A... Opening 16... Fitting convex portion 17... Connecting convex portion 18...Connecting recess 19...Protrusion 20...Storage space 21...Recess 22...Outer wall 23...Storage section 24...Step recess 25...Pressing protrusion 26...Deformation limiting protrusion 29...Storage recess 30...Laser welded section 31...Welding line 31A...Vertical weld line section 31B...Horizontal weld line section 32...Welding spot 40...Laminated section 44...Exposed terminal 50...Laser beam 51...Pusher 52...Base plate 53...Support rib 803...Terminal plate 901...Plastic 903...Terminal plate 906...Elastic arm plate

Claims

1. A breaker comprising all of the following configurations (a) to (i): (a) the breaker comprises a fixed contact metal plate having a fixed contact, an elastic arm plate having a movable contact at its tip, which is arranged in a position opposite to the fixed contact, a terminal plate formed by fixing an upper welding plate provided at the rear end of the elastic arm plate via a laser welding portion, a plastic case in which the terminal plate and the fixed contact metal plate are fixed, and a bimetal for pressing the elastic arm plate to switch the movable contact from on to off. (b) the case is made of plastic and has a hollow storage space therein in which the elastic arm plate is disposed. (c) the case has a connection terminal electrically connected to the fixed contact metal plate and a connection terminal electrically connected to the elastic arm plate disposed at each end of the bottom surface. (d) the terminal plate comprises a lower welding plate formed by welding the upper welding plate of the elastic arm plate exposed in the storage space of the case in a stacked state. (e) The terminal board connects the connection terminal to the side edge of the lower welding plate extending in the width direction of the case via a rising portion. (f) The terminal board arranges the connection terminal connected to the lower welding plate via the rising portion at the end of the bottom surface of the case. (g) The rising portion penetrates the case, is located in a plane parallel to the width direction of the case, is embedded in the plastic of the case, and arranges the lower welding plate in the storage space, and arranges the connection terminal on the bottom surface of the case. (h) The width (W1) of the lower welding plate is wider than the width (W2) of the upper welding plate, and the upper welding plate and the lower welding plate are closely attached and connected by a laser welding portion. (i) The connection terminal is arranged on the bottom surface of the case in an orientation extending in the vertical direction of the case from the connecting portion with the rising portion toward the tip.

2. A breaker as claimed in claim 1, wherein said terminal board comprises a pair of said connection terminals spaced apart from each other, and said pair of said connection terminals are arranged at the corners of the bottom surface of said case.

3. A breaker according to claim 1, wherein the laser welded portion is one or more weld lines extending linearly.

4. A breaker according to claim 1, wherein said laser weld is one or more weld spots.

5. The breaker according to claim 1, characterized in that it is a micro breaker, wherein the thickness of the elastic arm plate is 50 μm or more and 200 μm or less.

6. A breaker as claimed in claim 1, wherein the case has an outer peripheral wall in which the fixed contact metal plate and the terminal plate are embedded, and the inside of the outer peripheral wall is used as a storage space for arranging the elastic arm plate, and an exposed portion is provided within the storage space in which the lower welded plate of the terminal plate is exposed, and the terminal plate is formed by laminating the upper welded plate of the elastic arm plate on the lower welded plate and laser welding them together.

7. A breaker as claimed in any one of claims 1 to 6, characterized in that the fixed contact and the movable contact are activated contacts that have been activated by ultrasonic vibration in a current-carrying state.

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