JP2012160317A - Breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid interference of a movable contact and burrs generated on the boundary of a fixed piece and a resin case, when the resin case is moded by inserting the fixed piece in a breaker.SOLUTION: A stepped retreat part 33 is formed at the edge of a movable contact 3. Burrs 77 may be formed to cover a part of a fixed contact 21 on the boundary of a fixed piece 2 and the case body 71 of a resin case 7 during insert molding, but interference of the burrs 77 and the movable contact 3 is avoided by the retreat part 33 formed in the movable contact 3, thus ensuring excellent contact conduction of the fixed contact 21 and the movable contact 3.

Description

  The present invention relates to a small breaker built in a secondary battery.

  Conventionally, a safety device for a secondary battery such as a small nickel-metal hydride battery or a lithium-ion battery mounted on a mobile phone or a notebook personal computer has a PTC thermistor (the resistance value increases rapidly above a certain temperature). Conductive materials) and thermal fuses are used. Each of these protection circuits has a drawback that it is difficult to set a precise temperature with a wide operating temperature bandwidth, or that it cannot be used more than once, so that it is impossible to perform 100% inspection in the manufacturing process. . Therefore, in place of such a conventional protection circuit, there is a demand for a mechanically operated safety device that can set a precise operating temperature and withstand multiple use, and a movable contact at a predetermined operating temperature. Various techniques relating to a breaker having a thermally responsive element separated from a fixed contact have been proposed.

  For example, Patent Document 1 discloses a technique for processing the surface of the movable contact into a satin finish in order to stabilize the contact resistance between the fixed contact and the movable contact. Further, Patent Document 2 discloses a technique for forming an activation trace by energizing a fixed contact and a movable contact while applying vibration to destroy an oxide layer on the contact surface.

  FIG. 10 is an enlarged cross-sectional view in the vicinity of a fixed contact and a movable contact in a conventional breaker to which the technique described in the above-mentioned patent document can be applied. The breaker includes a fixed piece 2 having a fixed contact 21, a movable piece 4 to which the movable contact 3 is joined, a resin case 7 that accommodates the fixed piece 2 and the movable piece 4, and the like. The fixed piece 2 and the case main body 71 of the resin case 7 are integrated by insert molding. In insert molding, at the boundary between the fixed piece 2 and the case main body 71, the resin material forming the case main body 71 may protrude into the gap between the mold and the fixed piece 2 and a burr 77 may occur. In the breaker illustrated in FIG. 10, since the upper surface of the fixed contact 21 is designed to be sufficiently higher than the upper surface of the bottom wall 78 of the case main body 71, the burr 77 is formed between the fixed contact 21 and the movable contact 3. The contact surface 31 is not reached, and stable contact conduction is obtained by the above-described technique for forming the activation trace.

JP-A-2005-116511 JP 2000-207966 A

  In recent years, secondary batteries used in mobile phones, notebook computers, and the like have been increasingly miniaturized, and further miniaturization is required for breakers incorporated in secondary batteries. Therefore, the parts constituting the breaker such as the fixed piece 2, the movable contact 3, and the movable piece 4 are thinned to the limit satisfying requirements such as strength.

  FIG. 11 is an enlarged cross-sectional view of the vicinity of the fixed contact 21 and the movable contact 3 in a breaker aimed at further lowering the height under such a background. In this breaker, the upper surface of the fixed contact 21 and the upper surface of the bottom wall 78 of the case body 71 are designed to have substantially the same height, thereby thinning the case body 71 and reducing the space inside the breaker. To reduce the height.

  However, when the upper surface of the fixed contact 21 and the upper surface of the bottom wall 78 of the case body 71 are designed to be substantially the same height and become horizontal, as shown in FIG. The burr 77 generated beyond the design boundary 79 (see FIG. 5) between the fixed piece 2 and the case main body 71 may reach below the end edge of the movable contact 3, and the fixed contact 21 and the movable contact 3. Contact conduction between the two is hindered. In general, the amount of burrs 77 generated in resin molding varies depending on the molding time, the lot of the resin material, etc., so it is difficult to stably suppress the burrs 77 at low cost and without overloading the production site. . Of course, it is possible to avoid the interference between the movable contact 3 and the burr 77 by extending the tip of the movable piece 4 and moving the movable contact 3 in the left direction in the figure, but the total length of the breaker is enlarged. Therefore, it is impossible to reduce the size.

  The present invention has been made to solve the above-described problem, and reduces the possibility that the contact conduction between the fixed contact and the movable contact is hindered by the burr generated at the boundary between the fixed piece and the case main body of the resin case. However, it aims at providing the breaker which can achieve further size reduction.

  In order to achieve the above object, the present invention provides a fixed piece having a fixed contact, a movable contact joined to a tip, and a movable piece that presses and contacts the movable contact with the fixed contact. In a breaker comprising: a thermally responsive element that operates the movable piece so that the movable contact is separated from the fixed contact by being deformed; and a resin case that houses the fixed piece, the movable piece, and the thermally responsive element, The fixed contact and the resin case are integrated by insert molding, and the movable contact has a retracting portion retracted backward with respect to the fixed contact.

  In this breaker, the retracting portion is preferably formed in a stepped shape.

  In this breaker, it is preferable that the retracting portion is formed in a concave curved surface shape.

  Further, the present invention provides a fixed piece having a fixed contact, a movable contact joined to a tip, a movable piece that presses and contacts the movable contact with the fixed contact, and deforms according to a temperature change. In the breaker 1 including a thermally responsive element that operates the movable piece so that the movable contact is separated from the fixed contact, and a resin case that houses the fixed piece, the movable piece, and the thermally responsive element, the fixed contact and the The resin case is integrated by insert molding, and the contact surface between the movable contact and the fixed contact is smaller than the joint surface between the movable contact and the movable piece, and the contact between the movable contact and the fixed contact. The center of the surface is shifted from the center of the joint surface between the movable contact and the movable piece in parallel with the extending direction of the movable piece.

  In this breaker, the center of the contact surface between the movable contact and the fixed contact is shifted from the center of the joint surface between the movable contact and the movable piece in the distal direction of the movable piece. It is preferable.

  In this breaker, it is preferable that angles formed between two side surfaces of the movable contact and the movable piece facing each other in the extending direction of the movable piece are different from each other.

  According to the breaker of the present invention, the movable contact has a retracting portion that is retracted rearward with respect to the fixed contact, so that burrs may occur at the boundary between the fixed piece and the resin case during insert molding. However, it is possible to ensure good contact conduction between the fixed contact and the movable contact while avoiding interference between the burr and the movable contact. As a result, the yield can be maintained in the manufacture and mass production of breakers that are low in profile and small in size.

  Further, since the retracting portion is formed in a stepped shape or a concave curved surface shape, it is possible to further avoid interference between the burr and the movable contact even for a thick burr, and the fixed contact and the movable contact can be prevented. It is possible to ensure contact conduction between the two.

  In the configuration where the center of the contact surface between the movable contact and the fixed contact is shifted in the extending direction of the movable piece with respect to the center of the joint surface between the movable contact and the movable piece, insert molding is performed. In this case, contact conduction between the fixed contact and the movable contact can be ensured while avoiding interference between the burr and the movable contact generated at the boundary between the fixed piece and the resin case. Further, the contact surface between the movable contact and the fixed contact is smaller than the joint surface between the movable contact and the movable piece. In other words, the joint surface between the movable contact and the movable piece according to the present invention is a contact between the movable contact and the fixed contact. It is larger than the surface and is the same as that of the conventional breaker. Therefore, the joining force between the movable contact and the movable piece can be ensured equivalent to that of the conventional breaker.

  In addition, the center of the contact surface between the movable contact and the fixed contact is shifted from the center of the joint surface between the movable contact and the movable piece in the direction of the tip of the movable piece. In a configuration where the boundary portion is formed in the vicinity of the movable contact and on the proximal end side of the movable piece, it is possible to ensure contact conduction between the fixed contact and the movable contact while avoiding interference between the burr and the movable contact. it can.

  In addition, the angle formed between the two side surfaces of the movable contact facing each other in the extending direction of the movable piece and the movable piece is different from each other, so that the burr and the movable contact can be interfered with each other with a simple shape. This can be avoided, and contact conduction between the fixed contact and the movable contact can be ensured.

The assembly perspective view which shows the structure of the breaker by one Embodiment of this invention. Sectional drawing which shows operation | movement of the breaker in a normal charge or discharge state. Sectional drawing which shows operation | movement of a breaker in the time of an overcharge state or abnormality. The perspective view which shows the shape of a movable contact. Sectional drawing which expands and shows a contact and its vicinity. Sectional drawing which shows the relationship between a burr | flash and a movable contact. Sectional drawing which shows the relationship between the burr | flash and movable contact in the modification of this embodiment. Sectional drawing which shows the relationship between the burr | flash and movable contact in another modification of this embodiment. Sectional drawing which shows the shape of the movable contact in another modification of this embodiment. Sectional drawing which expands and shows the contact in a conventional breaker, and its vicinity. Sectional drawing which expands and shows the contact in the breaker which aimed at the conventional low profile, and its vicinity.

  A breaker according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of the breaker. The breaker 1 includes a fixed piece 2 having a fixed contact 21, a movable piece 4 having a movable contact 3 at the tip, a thermally responsive element 5 that deforms with a change in temperature, a PTC (Positive Temperature Coefficient) thermistor 6, , A fixed piece 2, a movable piece 4, a thermally responsive element 5, and a resin case 7 that accommodates a PTC thermistor 6. The resin case 7 includes a case body 71 and a lid member 72 attached to the upper surface of the case body 71.

  The fixed piece 2 is formed by pressing a metal plate mainly composed of phosphor bronze (in addition, a metal plate such as copper-titanium alloy, white or brass), and is incorporated into the case body 71 by insert molding. ing. A terminal 22 is formed at one end of the fixed piece 2, and a PTC thermistor 6 is placed at the center. The fixed contact 21 is formed by cladding, plating, coating, or the like of a conductive material such as copper, silver alloy, gold-silver alloy in addition to silver, nickel, nickel-silver alloy, and formed above the case body 71. It is exposed from a part of the opening 73 formed. The terminal 22 protrudes outward from one end of the case body 71.

  The movable piece 4 is formed in an arm shape by pressing a metal plate equivalent to the fixed piece 2. A terminal 41 is formed at one end in the longitudinal direction of the movable piece 4 and protrudes outward from the case body 71, and a movable contact 3 is formed at the other end (corresponding to the tip of the arm-shaped movable piece 4). The movable contact 3 is formed of the same material as that of the fixed contact 21 and is joined to the tip of the movable piece 4 by a technique such as welding. The movable piece 4 has a fixed portion 42 (corresponding to the base end of the arm-shaped movable piece 4) and an elastic portion 43 between the movable contact 3 and the terminal 41. The movable piece 4 is fixed by being sandwiched between the case main body 71 and the lid member 72 in the fixed portion 42, and the elastic portion 43 is elastically deformed, whereby the movable contact 3 formed at the tip thereof is pressed against the fixed contact 21 side. Thus, the fixed piece 2 and the movable piece 4 can be energized.

  In addition, a small protrusion 44 is formed on the lower surface of the elastic portion 43 so as to face the thermally responsive element 5. The small protrusions 44 and the thermally responsive element 5 are always in contact with each other, and the deformation of the thermally responsive element 5 is transmitted to the elastic portion 43 (see FIGS. 2 and 3). The material of the movable piece 4 is preferably a material mainly composed of phosphor bronze. In addition, a conductive elastic material such as copper-titanium alloy, white or brass is also used. Note that the movable piece 4 is curved or bent at the elastic portion 43 by press working. The degree of bending or bending is not particularly limited as long as the thermally responsive element 5 can be accommodated, and may be set as appropriate in consideration of the elastic force at the operating temperature and the return temperature, the pressing force of the contacts, and the like.

  The thermally responsive element 5 has an arcuate shape and is made of a composite material such as bimetal or trimetal. When the operating temperature is reached due to overheating, the curved shape is reversed, and when it falls below the return temperature due to cooling, it is restored. Since the thermoresponsive element 5 is usually a bimetal, it is hereinafter referred to as a bimetal 5 unless otherwise specified. The shape of the bimetal 5 can be formed by pressing. The material and shape of the bimetal 5 are not particularly limited as long as the elastic part 43 of the movable piece 4 is pushed up by the reversing operation of the bimetal 5 at a predetermined temperature and returns to the original state by the elastic force of the elastic part 43. From the viewpoint of productivity and efficiency of the reversal operation, a rectangle is desirable, and a rectangle close to a square is desirable in order to efficiently push up the elastic portion 43 while being small. Examples of the material of the bimetal 5 include various materials such as white, brass and stainless steel, including a copper-nickel-manganese alloy or nickel-chromium-iron alloy on the high expansion side and an iron-nickel alloy on the low expansion side. A material obtained by laminating two types of materials having different thermal expansion coefficients made of the above alloys is used in combination according to the required conditions.

  When the energization of the fixed piece 2 and the movable piece 4 is interrupted by the reversing operation of the bimetal 5, the current flowing through the PTC thermistor 6 increases. As long as the PTC thermistor 6 is a positive temperature coefficient thermistor that limits the current by increasing the resistance value as the temperature rises, the type of operation current, operation voltage, operation temperature, return temperature, etc. can be selected as necessary. The shape is not particularly limited as long as these properties are not impaired.

  The case main body 71 and the lid member 72 constituting the resin case 7 are formed of a resin such as flame retardant polyamide, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT) having excellent heat resistance. ing. The case body 71 is formed with an opening 73 for accommodating the fixed piece 2, the movable piece 4, the bimetal 5, the PTC thermistor 6, and the like. The movable piece 4, the bimetal 5 and the PTC thermistor 6 incorporated in the case body 71 are brought into contact with each other by frames 74, 75 and 76 formed inside the opening 73, respectively, and are guided when the bimetal 5 is reversed. The In the present embodiment, like the conventional breaker shown in FIG. 11, the upper surface of the fixed contact 21 and the upper surface of the bottom wall 78 of the case body 71 are designed to be substantially the same height and to be horizontal. Thus, the case main body 71 is thinned and the space inside the breaker is reduced to reduce the height.

  As shown in FIG. 1, a lid member 72 is mounted on the upper surface of the case body 71 so as to close the opening 73 of the case body 71 that houses the fixed piece 2, the movable piece 4, the bimetal 5, the PTC thermistor 6, and the like. The The case main body 71 and the lid member 72 are joined by ultrasonic welding. The lid member 72 may have a metal part. Having a metal part is advantageous for miniaturization from the viewpoint of mechanical strength. Further, by providing a cover terminal on the metal part, it is possible to supply a spare power source to other parts of the safety device.

  FIG. 2 shows the operation of the breaker 1 in a normal charge or discharge state. In a normal charge or discharge state, the bimetal 5 is rotating forward (before reversal), the fixed contact 21 and the movable contact 3 are in contact, and both terminals 22 of the breaker 1 through the elastic portion 43 of the movable piece 4 and the like. , 41 are electrically connected. The elastic part 43 of the movable piece 4 and the bimetal 5 are in contact with each other, and the movable piece 4, the bimetal 5, the PTC thermistor 6 and the fixed piece 2 are electrically connected as a circuit. However, since the resistance of the PTC thermistor 6 is overwhelmingly larger than the resistance of the movable piece 4, the current flowing through the PTC thermistor 6 is completely ignored compared to the amount flowing through the fixed contact 21 and the movable contact 3. It is possible.

  FIG. 3 shows the operation of the breaker 1 in an overcharged state or an abnormality. When the PTC thermistor 6 is overheated due to overcharging or abnormalities, the bimetal 5 that has reached the operating temperature is reversed, the elastic portion 43 of the movable piece 4 is pushed up, and the fixed contact 21 and the movable contact 3 are separated. To do. At this time, the current flowing between the fixed contact 21 and the movable contact 3 is interrupted, and a slight leakage current flows through the bimetal 5 and the PTC thermistor 6. Since the PTC thermistor 6 continues to generate heat as long as such a leakage current flows, and the resistance value is drastically increased while maintaining the bimetal 5 in the inverted state, the current does not flow through the path between the fixed contact 21 and the movable contact 3, There is only a small leakage current as described above. This leakage current can be used for other functions of the safety device.

  When the overcharge state is canceled or the abnormal state is resolved, the PTC thermistor 6 is no longer heated, and the bimetal 5 returns to the return temperature and is restored to the normal rotation shape. Then, the movable contact 3 and the fixed contact 21 come into contact again by the elastic force of the elastic portion 43 of the movable piece 4, the circuit is released from the interruption state, and returns to the conduction state shown in FIG.

  FIG. 4 shows the shape of the movable contact 3 viewed from the bottom. FIG. 5 is an enlarged view of the fixed contact 21, the movable contact 3 and the vicinity thereof in the normal charge or discharge state shown in FIG. The movable contact 3 has a contact surface 31 to which the fixed contact 21 is contacted and a joint surface 32 to which the movable piece 4 is joined. Since the joining surface 32 must be joined to the distal end portion of the movable piece 4 accurately and firmly, a certain area or more is required. On the other hand, the contact surface 31 does not need to be so large in the normal charge or discharge state shown in FIGS. 2 and 5 as long as the contact resistance can be secured to such an extent that a necessary current can flow. Therefore, the area of the contact surface 31 of the movable contact 3 is set smaller than the area of the joint surface 32.

  On the contact surface 31 of the movable contact 3, the base end side of the movable piece 4, that is, the edge on the fixed portion 42 side, is fixed to the fixed contact 21 (when the direction from the movable contact 3 toward the fixed contact 21 is the front). ) A retracting portion 33 that is retracted rearward, that is, upward in FIG. 5 is provided. The retracting portion 33 retracts the surface of the movable contact 3 toward the movable piece 4 at the end of the movable contact 3 on the base end side (the arrow-X direction side in FIG. 4) of the movable piece 4. It is provided by forming the edge in a stepped shape. The evacuation part 33 may be formed in a step shape over a plurality of stages. As shown in FIGS. 4 and 5, as a result of providing the retracting portion 33 in the movable contact 3, the center 31 a of the contact surface 31 is in the distal direction of the movable piece 4 with respect to the center 32 a of the joining surface 32 (in FIG. 4, In the direction of arrow X), the position is shifted by a distance ΔX. In other words, the center line 31 b of the contact surface 31 perpendicular to the longitudinal direction of the movable piece 4 is positioned with a distance ΔX in the distal direction of the movable piece 4 with respect to the center line 32 b of the joining surface 32.

  FIG. 6 shows the fixed contact 21, the movable contact 3, and the vicinity thereof in an individual in which a large burr is generated at the boundary between the fixed piece 2 and the case main body 71 during insert molding. As already described, in the present embodiment, the upper surface of the fixed contact 21 and the upper surface of the bottom wall 78 of the case body 71 are designed to be substantially the same height and become horizontal. Thus, a structure in which burrs 77 are likely to occur is obtained. The large burr 77 generated as described above may cover a part of the fixed contact 21 and be interposed below the movable contact 3. However, in the present embodiment, since the stepped retraction portion 33 is formed at the edge of the movable contact 3, interference between the burr 77 and the movable contact 3 is avoided. As a result, the yield can be maintained in the manufacture and mass production of breakers that are low in profile and small in size. Good contact conduction between the fixed contact 21 and the movable contact 3 can be ensured. Further, the joint surface 32 between the movable contact 3 and the movable piece 4 is larger than the contact surface 31 between the movable contact 3 and the fixed contact 21, and is equivalent to the conventional movable contact 3 shown in FIGS. The movable contact 3 and the movable piece 4 can be joined in the same manner while securing the joining force between the movable contact 3 and the movable piece 4 equivalent to that of the conventional breaker 1.

  The region where the above-described retracting portion 33 is formed is set so as to avoid contact between the burr 77 and the movable contact 3. For example, in FIG. 5, when a part of the movable contact 3 exists above the design boundary portion 79 between the case main body 71 and the fixed piece 2, the retracting portion 33 is provided in the movable contact 3. More specifically, the retracting portion 33 is a range in which at least the designed boundary portion 79 and the movable contact point (joining surface 32 including the outer edge) overlap in a plan view (see through from the top of the drawing in FIG. 5). Is formed at the end edge of the movable contact 3. The retracting portion 33 can be formed by a normal metal forming process such as a cutting process or a press process.

  Even if the design boundary part 79 is outside the range where the joint surface 32 overlaps in the plan view, the overlap as described above is caused by the design boundary part 79 and the edge of the movable contact 3 on the fixed piece 2. May occur substantially when the gap is sufficiently small. For example, the distance between the design boundary 79 on the fixed piece 2 and the edge of the movable contact 3 is the dimensional tolerance and assembly tolerance (hereinafter referred to as the movable contact 3, the movable piece 4, the fixed piece 2, the case body 71, etc.). If it is within the range of the manufacturing tolerance, it is a matter of course that the above-mentioned overlap is substantially generated, and the area where the burr 77 can be leached out from the design boundary 79 is in plan view with the joint surface 32. Even when reaching the range where the overlap occurs, it can be said that the movable contact 3 and the design boundary 79 substantially overlap. The retracting portion 33 is provided corresponding to the design overlap and substantial overlap between the design boundary 79 and the movable contact 3.

  In actual mass-produced products, in order to avoid contact between the burr 77 and the movable contact 3, the dimensions of each part of the retracting portion 33 are based on sufficient consideration of the manufacturing tolerance and the size of the burr 77. Must be determined. Since the manufacturing tolerance and the size of the burr 77 vary depending on the resin material to be used, equipment used for manufacturing, manufacturing time, manufacturing method, and the like, the dimensions of each part of the retracting portion 33 are appropriately determined according to these factors.

  FIG. 7 shows a modification of the breaker 1 according to the above embodiment. In this breaker 1, the shape of the retracting portion 33 in the movable contact 3 is different from that shown in FIGS. That is, the retracting portion 33 is provided by forming the end edge of the movable contact 3 on the side of the fixed portion 42 of the movable piece 4 in a concave curved surface shape. Also in this modification, the area of the contact surface 31 of the movable contact 3 is set smaller than the area of the joint surface 32, and the center 31 a of the contact surface 31 is the tip of the movable piece 4 with respect to the center 32 a of the joint surface 32. The feature points that are displaced in the direction are the same as those of the breaker 1 shown in FIGS. According to the breaker 1 of this modified example, since the retracting portion 33 is formed in a concave curved surface shape, it is possible to further avoid interference between the burr 77 and the movable contact 3 even with respect to the thick burr 77. Thus, the contact conduction between the fixed contact 21 and the movable contact 3 can be more reliably maintained.

  FIG. 8 shows another modification of the breaker 1 according to the above embodiment. In this breaker 1, the shape of the movable contact 3 is different from that shown in FIGS. The angles formed by the two side surfaces 36a, 36b of the movable contact 3 and the bottom surface of the movable piece 4 that are opposed to each other in the extending direction of the movable piece 4 (longitudinal direction of the movable piece 4) are different from each other. That is, the internal angle formed between the side surface 36 a and the bottom surface of the movable piece 4 is set larger than the internal angle formed between the side surface 36 b and the bottom surface of the movable piece 4. By forming the side surfaces 36a and 36b so as to satisfy such a relationship, also in this modification, the area of the contact surface 31 of the movable contact 3 is set smaller than the area of the joint surface 32, and the contact surface 31 The center 31 a of the movable piece 4 is positioned so as to be shifted from the center 32 a of the joining surface 32 in the distal direction. According to the breaker 1 of the present modification, it is possible to avoid interference between the burr 77 and the movable contact 3 with a simple shape, and to ensure contact conduction between the fixed contact 21 and the movable contact 3. .

  Also in this modification, the area of the contact surface 31 of the movable contact 3 is set smaller than the area of the joint surface 32, and the center 31 a of the contact surface 31 is the tip of the movable piece 4 with respect to the center 32 a of the joint surface 32. The feature points that are displaced in the direction are the same as those of the breaker 1 shown in FIGS.

  The present invention is not limited to the configuration of the embodiment described above, and the center 31a of the contact surface 31 between the movable contact 3 and the fixed contact 21 is relative to the center 32a of the joint surface 32 between the movable contact 3 and the movable piece 4. Thus, it suffices if the position is shifted in the tip direction of the movable piece 4 (that is, the arrow X direction in FIG. 4). According to such a configuration, when the case main body 71 is formed by inserting the fixed piece 2, it is generated by the resin material flowing from the base end side of the movable piece 4 at the boundary between the fixed piece 2 and the case main body 71. Contact conduction between the fixed contact 21 and the movable contact 3 can be ensured while avoiding interference between the burr 77 and the movable contact 3.

  Further, depending on the shapes of the fixed piece 2 and the case main body 71, burrs may be generated by the resin material flowing from the front end side of the movable piece 4 at the boundary between the fixed piece 2 and the case main body 71. In such a configuration, the center 31 a of the contact surface 31 between the movable contact 3 and the fixed contact 21 is in the proximal direction of the movable piece 4 with respect to the center 32 a of the joint surface 32 between the movable contact 3 and the movable piece 4. What is necessary is just to be shifted | deviated (namely, arrow-X direction in FIG. 4). That is, the center 31 a of the contact surface 31 between the movable contact 3 and the fixed contact 21 is shifted in parallel with the extending direction of the movable piece 4 with respect to at least the center 32 a of the joint surface 32 between the movable contact 3 and the movable piece 4. As long as it is located.

  The various movable contacts 3 described above can also be applied to other types of breakers. For example, in the breaker 1 shown in FIG. 1, an elastic portion 43 is extended instead of the fixed portion 42 on the opposite side to the bimetal 5 and the PTC thermistor 6, and another movable contact is formed at the tip thereof. It is the same as that of the above also about the form of the both-sides contact connected with the fixed piece provided separately instead of the terminal 41. FIG. Further, the present invention is similarly applied to a mode in which the movable piece and the thermally responsive element are integrally formed (the movable piece is formed of a laminated metal having two or more layers). Furthermore, the same applies to a form in which the fixing piece 2 is insert-molded on the lid member 72.

  FIG. 9 shows a movable contact 3 in another modification of the breaker 1 according to the above embodiment. Depending on the shapes of the fixed piece 2 and the case main body 71, burrs may be generated by the resin material that has flowed in from both the distal end side and the proximal end side of the movable piece 4. Therefore, in this modification, by providing the retracting portions 33 at both ends of the movable contact 3, contact conduction between the fixed contact 21 and the movable contact 3 is achieved while avoiding interference between the burr and the movable contact 3. Can be secured. In addition, in this modification, it is good also as a structure which provides the retracting part 33 of the shape shown in FIG.

DESCRIPTION OF SYMBOLS 1 Breaker 2 Fixed piece 3 Movable contact 4 Movable piece 5 Thermally responsive element (bimetal)
7 Resin case 21 Fixed contact 31 Contact surface 32 Joint surface 33 Retraction part 71 Case body 77 Burr 79 Design boundary part

Claims (6)

A fixed piece having a fixed contact, a movable contact is joined to the tip, a movable piece that presses and contacts the movable contact with the fixed contact, and the movable contact is deformed according to a temperature change so that the movable contact becomes the fixed contact. In a breaker comprising a thermally responsive element that operates the movable piece so as to be separated from a resin case that houses the fixed piece, the movable piece, and the thermally responsive element,
The fixed contact and the resin case are integrated by insert molding,
The breaker characterized in that the movable contact has a retracting portion retracted backward with respect to the fixed contact.   The breaker according to claim 1, wherein the retracting portion is formed in a step shape.   The breaker according to claim 1, wherein the retracting portion is formed in a concave curved surface shape. A fixed piece having a fixed contact, a movable contact is joined to the tip, a movable piece that presses and contacts the movable contact with the fixed contact, and the movable contact is deformed according to a temperature change so that the movable contact becomes the fixed contact. In a breaker comprising a thermally responsive element that operates the movable piece so as to be separated from a resin case that houses the fixed piece, the movable piece, and the thermally responsive element,
The fixed contact and the resin case are integrated by insert molding,
The contact surface between the movable contact and the fixed contact is smaller than the joint surface between the movable contact and the movable piece,
The center of the contact surface between the movable contact and the fixed contact is positioned so as to be shifted parallel to the extending direction of the movable piece with respect to the center of the joint surface between the movable contact and the movable piece. A featured breaker.   The center of the contact surface between the movable contact and the fixed contact is shifted from the center of the joint surface between the movable contact and the movable piece in the distal direction of the movable piece. The breaker of Claim 1 or Claim 4.   The breaker according to claim 4 or 5, wherein angles formed between two side surfaces of the movable contact facing each other in the extending direction of the movable piece and the movable piece are different from each other.

Images