JP6224920B2 - Breaker, safety circuit including the same, and secondary battery circuit - Google Patents

Description

  The present invention relates to a small breaker built in a secondary battery pack or the like of an electric device.

  Conventionally, a breaker is used as a protection device (safety circuit) for secondary batteries and motors of various electric devices. When the temperature of the secondary battery during charging / discharging rises excessively, or when an abnormality occurs such as when an overcurrent flows through a motor or the like equipped in a device such as an automobile or home appliance, Cut off current to protect secondary batteries and motors. Breakers used as such protective devices operate accurately following temperature changes (having good temperature characteristics) and have stable resistance when energized to ensure the safety of the equipment. It is required to be.

  In addition, when the breaker is used as a protection device for a secondary battery or the like installed in an electric device such as a thin-type multifunctional mobile phone called a notebook personal computer, a tablet-type portable information terminal device, or a smartphone, the above-described case is used. In addition to ensuring safety, miniaturization is required. In particular, in recent portable information terminal devices, users have a strong desire for miniaturization (thinning), and devices newly released by each company are designed to be small in order to ensure superiority in design. The tendency to be remarkable is remarkable. Against this background, breakers that are mounted together with secondary batteries as one component of portable information terminal devices are also strongly required to be further miniaturized.

  The breaker is provided with a thermally responsive element that operates according to a temperature change and conducts or cuts off a current. Patent Document 1 discloses a breaker to which a bimetal is applied as a thermally responsive element. Bimetal is an element that is formed by laminating two types of plate-like metal materials having different coefficients of thermal expansion, and controls the conduction state of the contact by changing the shape in accordance with a temperature change. The breaker shown in the same document is a case in which parts such as a fixed piece (base terminal), a movable piece (movable arm), a thermally responsive element, and a PTC thermistor are housed in a case. Used by connecting to the electrical circuit of electrical equipment. The case is usually made of a resin material such as thermoplastic in consideration of ease of molding and cost.

WO2011 / 105175 gazette

  However, in the breaker having the structure shown in the above patent document, sufficient adhesion cannot be obtained between the movable piece constituted by a metal plate mainly composed of phosphor bronze or the like, the resin base, and the cover member. When a breaker is used for a long time in an atmosphere with extremely high temperature and humidity, there is a risk that water vapor may enter the internal space that accommodates the thermal actuator and the like. There is a concern that the water vapor that has entered the internal space of the breaker may adversely affect the metal that constitutes the thermally responsive element.

  In recent years, with the aim of improving production efficiency, a form in which the breaker is directly mounted on the circuit board has been studied. Furthermore, reflow soldering is used to connect the breaker terminal and the circuit board lead. Use is under consideration. However, the flux may enter from a slight gap generated between the movable piece, the resin base, and the cover member, which contributes to the above-mentioned concern.

  The present invention has been made to solve the above-mentioned problems, and maintains the normal heat deformation operation of the thermoresponsive element by improving the airtightness of the case and preventing the adverse effect on the metal such as the thermoresponsive element. And it aims at providing the breaker which can acquire a favorable temperature characteristic.

  In order to achieve the above object, a breaker of the present invention includes a fixed piece having a fixed contact, a movable contact, a movable piece that presses the movable contact against the fixed contact, and a temperature change. A thermally responsive element that operates the movable piece so that the movable contact is separated from the fixed contact by being deformed, a first case having a housing portion that houses the thermally responsive element, and a first case that is attached to the first case. In the breaker including the second case, the first case and the second case are joined over the entire circumference outside the housing portion.

  The breaker according to the present invention further includes a cover piece integrally formed with the second case, and the second case includes a peripheral edge formed on a peripheral edge of the cover piece and a continuous portion from the peripheral edge. It is desirable to have an inner surface portion formed on the inner surface side of the cover piece, and to be joined to the first case at the inner surface portion.

  In the breaker according to the present invention, it is preferable that a protruding portion that protrudes toward the first case and constitutes a side wall of the housing portion is formed on the inner surface portion of the second case.

  In the breaker according to the present invention, it is desirable that the inner surface portion of the second case has an abutting portion that abuts on the thermally responsive element when the thermally responsive element is thermally deformed.

  In the breaker according to the present invention, it is preferable that the cover piece has a terminal protruding from the second case.

  In the breaker according to the present invention, it is desirable that the cover piece has a joint portion on the inner surface thereof to which a part of the movable piece is joined.

  In the breaker according to the present invention, it is desirable that the cover piece is embedded in the protruding portion between the terminal and the joint portion.

  In the breaker according to the present invention, it is desirable that the movable piece is joined to the cover piece in a region overlapping with the thermally responsive element in plan view.

  In addition, a safety circuit for an electric device according to the present invention includes the breaker.

  In addition, a secondary battery pack according to the present invention includes the breaker.

  According to the breaker of the present invention, since the first case and the second case are joined over the entire circumference outside the accommodating portion, the internal space of the accommodating portion is sealed and isolated from the outside of the breaker. The As a result, the airtightness of the case is enhanced, it is possible to prevent adverse effects on the metal and the like constituting the thermoresponsive element, the normal thermal deformation operation of the thermoresponsive element is maintained, and good temperature characteristics can be obtained. .

  The second case has a peripheral portion formed on the periphery of the cover piece and an inner surface portion formed on the inner surface side of the cover piece continuously from the peripheral portion, and is joined to the first case on the inner surface portion. According to the configuration, it is possible to improve the sealing performance of the housing portion while reducing the height dimension of the breaker.

  According to the configuration in which the protruding portion that protrudes toward the first case is formed on the inner surface portion of the second case, the second case and the cover piece are firmly joined to each other at the protruding portion, and the case is more airtight. Increased further. Furthermore, since the protruding portion constitutes the side wall of the housing portion, the position and posture of the thermally responsive element are stabilized and good temperature characteristics can be obtained.

  According to the configuration in which the inner surface of the second case has a contact portion that comes into contact with the heat responsive element when the heat responsive element is thermally deformed, it is possible to increase the amount by which the movable piece is pushed up by the heat responsive element. Thereby, the stability of the current interruption operation by the breaker can be enhanced without increasing the height dimension of the breaker.

  According to the configuration in which the cover piece has a terminal protruding from the second case, the configuration around the movable piece is simplified, so that the degree of freedom in designing the breaker is increased.

  According to the configuration in which the cover piece has a joint portion on the inner surface where a part of the movable piece is joined, since the posture of the movable piece is stable, the contact pressure between the fixed contact and the movable contact is stable, In addition, the resistance value can be stabilized and good temperature characteristics can be obtained.

  According to the configuration in which the cover piece is embedded in the protruding portion between the terminal and the joint, the airtightness of the case is further improved, the strength and rigidity of the case are increased, and the posture of the movable piece is increased. More stable.

  According to the configuration in which the joint portion is provided in the region overlapping with the thermally responsive element in plan view, the cover piece and the second case can be reduced in size.

  Moreover, according to the safety circuit or secondary battery circuit provided with the breaker of the present invention, it is possible to manufacture a safety circuit or secondary battery circuit that ensures safety due to excellent temperature characteristics.

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 the energized state at the time of normal charge or discharge. Sectional drawing which shows operation | movement of the breaker in the electric current interruption state, such as at the time of an overcharge state or abnormality. The perspective view which shows the structure of the movable piece of the same breaker, a cover member, and a cover piece from the inner surface side. Sectional drawing which shows the process of inserting the cover piece and shape | molding a cover member. Sectional drawing which shows the process of assembling the breaker. Sectional drawing which shows the joining state of the resin base and a cover member in a breaker. The perspective view which shows the structure of the modification of a breaker. The perspective view which shows the structure of another modification of a breaker. The perspective view which shows the structure of another modification of a breaker. Sectional drawing which shows the structure of another modification of a breaker. Sectional drawing which shows the structure of another modification of a breaker. The top view which shows the structure of the secondary battery pack provided with the breaker of this invention. The circuit diagram of the safety circuit provided with the breaker of this invention.

  A breaker according to an embodiment of the present invention will be described with reference to the drawings. 1 to 3 show 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, a case 7 for housing a PTC thermistor 6, and the like. The case 7 includes a resin base (first case) 71, a cover member (second case) 72 attached to the upper surface of the resin base 71, a cover piece 8, and the like.

  The fixing piece 2 is formed by pressing a metal plate mainly composed of phosphor bronze or the like (other metal plate such as copper-titanium alloy, white or brass) and embedded in the resin base 71 by insert molding. It is. A terminal 22 electrically connected to an external circuit is formed at one end of the fixed piece 2, and a support portion 23 that supports the PTC thermistor 6 is formed at the other end side. The PTC thermistor 6 is placed on the projections (dowels) 24a formed at three places on the support portion 23 of the fixed piece 2, and is supported by the projections 24a. The fixed contact 21 is formed at a position facing the movable contact 3 by cladding, plating, coating, or the like of a conductive material such as silver, nickel, nickel-silver alloy, copper-silver alloy, gold-silver alloy. The resin base 71 is exposed from a part of the opening 73c formed above. The terminal 22 protrudes outward from one end of the resin base 71.

  The fixed piece 2 is exposed at the terminal 22, the fixed contact 21 and the support portion 23, and is embedded in the resin base 71 between the terminal 22 and the fixed contact 21 and between the fixed contact 21 and the support portion 23. The surface of the support portion 23 of the fixed piece 2 is exposed to the accommodation space inside the case 7 and is in electrical contact with the PTC thermistor 6 through the protrusion 24a.

  The movable piece 4 is formed in an arm shape symmetrical to the center line in the longitudinal direction by pressing a plate-like metal material. As a material of the movable piece 4, a material mainly composed of phosphor bronze or the like equivalent to the fixed piece 2 is preferable. In addition, a conductive elastic material such as copper-titanium alloy, white or brass may be used. At one end in the longitudinal direction of the movable piece 4, a joining portion 42 (corresponding to the base end of the arm-like movable piece 4) that is joined to the inner surface of the cover piece 8 is formed. The joint portion 42 is joined to the joint portion 82 provided on the inner surface of the cover piece 8 by welding or the like. A movable contact 3 is formed at the other end of the movable piece 4 (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 clad or crimping in addition to welding. The movable piece 4 has an elastic portion 43 between the movable contact 3 and the joint portion 42. The elastic portion 43 extends from the joint portion 42 to the movable contact 3 side. When the movable piece 4 is fixed by the cover piece 8 at the joint portion 42 and the elastic portion 43 is elastically deformed, the movable contact 3 formed at the tip of the movable portion 4 is pressed and brought into contact with the fixed contact 21 side, and the fixed piece 2 and the movable piece 4 can be energized.

  The movable piece 4 is curved or bent at the elastic portion 43 by pressing. The degree of bending or bending is not particularly limited as long as the thermally responsive element 5 can be accommodated, and may be appropriately set in consideration of the elastic force at the operating temperature and the return temperature, the pressing force of the contact point, and the like. In addition, a protrusion (contact portion) 44 is formed on the lower surface of the elastic portion 43 so as to face the thermally responsive element 5. The projection 44 and the thermal response element 5 come into contact with each other when the thermal response element 5 is thermally deformed, and the deformation of the thermal response element 5 is transmitted to the elastic portion 43 via the projection 44 (see FIG. 3).

  The thermally responsive element 5 has an initial shape curved in an arc 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 reversely warped with snap motion, and is restored when the temperature falls below the return temperature due to cooling. The initial shape of the thermoresponsive element 5 can be formed by pressing. As long as the elastic portion 43 of the movable piece 4 is pushed up by the reverse warping operation of the thermal response element 5 at a desired temperature and returns to the original state by the elastic force of the elastic portion 43, the material and shape of the thermal response element 5 are particularly limited. Although not intended, a rectangular shape is desirable from the viewpoint of productivity and efficiency of reverse warping operation, and it is desirable that the rectangular shape is close to a square in order to efficiently push up the elastic portion 43 while being small. Examples of the material of the thermally responsive element 5 include, for example, white, brass, and stainless steel including copper-nickel-manganese alloy or nickel-chromium-iron alloy on the high expansion side and iron-nickel alloy on the low expansion side. A laminate of two types of materials having different coefficients of thermal expansion made of various alloys such as steel 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 reverse warping operation of the thermal response element 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 material and shape are not particularly limited as long as these properties are not impaired. In the present embodiment, a ceramic sintered body containing barium titanate, strontium titanate or calcium titanate is used. In addition to the ceramic sintered body, a so-called polymer PTC in which conductive particles such as carbon are contained in a polymer may be used.

  The resin base 71 and the cover member 72 constituting the case 7 are thermoplastic such as flame retardant polyamide (PA), heat-resistant polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT), etc. Molded with resin. A material other than the resin may be applied as long as characteristics equal to or higher than those of the above-described resin can be obtained. The resin base 71 houses a housing portion 73 for housing the thermally responsive element 5, the PTC thermistor 6, etc., a recess 73 a for housing the protruding portion 95 of the cover member 72, an opening 73 b, and the movable contact 3. An opening 73c for the purpose is formed. The shapes of the recess 73 a and the opening 73 b correspond to the protrusion 95. Note that the edge of the thermally responsive element 5 incorporated in the resin base 71 is brought into contact with a frame formed inside the accommodating portion 73 and is guided when the thermally responsive element 5 is reversely warped.

  A cover piece 8 is embedded in the cover member 72 by insert molding. The cover piece 8 supports the movable piece 4, reinforces the cover member 72, and contributes to downsizing of the breaker 1 while enhancing the rigidity and strength of the cover member 72 and thus the case 7 as a casing. The cover piece 8 is formed by pressing a metal plate mainly composed of the above-described phosphor bronze or the like or a metal plate such as stainless steel.

  The cover piece 8 has a terminal 81 at its tip. The bottom surface of the terminal 81 is formed on the same plane as the bottom surface of the resin base 71 and the bottom surface of the terminal 22 of the fixed piece 2. The cover piece 8 has a joint portion 82 to which the movable piece 4 is joined on the inner surface thereof, and an exposed portion 83 exposed from the cover member 72 to the outside of the breaker 1 on the outer surface thereof.

  The joint portion 82 is provided in a region overlapping with the thermally responsive element 5 in plan view. Thereby, size reduction of the cover piece 8 and the cover member 72 can be achieved. The exposed portion 83 is exposed to the outside of the breaker 1 through the opening 91 formed in the cover member 72. The outer surface of the exposed portion 83 and the outer surface of the cover member 72 are formed on the same plane. Thereby, the height dimension of the breaker 1 can be made small.

  As shown in FIG. 1, the cover member 72 is attached to the resin base 71 so as to close the housing portion 73 of the resin base 71 that houses the fixed piece 2, the movable piece 4, the thermally responsive element 5, the PTC thermistor 6, and the like. Mounted on top. The resin base 71 and the cover member 72 are joined by, for example, ultrasonic welding.

  FIG. 2 shows the operation of the breaker 1 in a normal charge or discharge state. In a normal charging or discharging state, the thermally responsive element 5 maintains the initial shape (before reverse warping), the fixed contact 21 and the movable contact 3 are in contact, the elastic portion 43 of the movable piece 4, the cover piece 8, etc. The terminals 22 and 81 of the breaker 1 are electrically connected. The elastic part 43 of the movable piece 4 and the thermal responsive element 5 are in contact, and the movable piece 4, the thermal responsive element 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 substantially larger than the amount flowing through the fixed contact 21 and the movable contact 3. It can be ignored.

  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 abnormality, the thermal actuator 5 that has reached the operating temperature is warped in reverse, and the elastic portion 43 of the movable piece 4 is pushed up so that the fixed contact 21 and the movable contact 3 Are separated from each other. 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 thermal actuator 5 and the PTC thermistor 6. Since the PTC thermistor 6 continues to generate heat as long as such a leakage current flows, the resistance value is drastically increased while maintaining the thermally actuated element 5 in the reverse warped state, so that the current is a path between the fixed contact 21 and the movable contact 3. There is only the above-described slight leakage current (which constitutes a self-holding circuit). 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 heat generation of the PTC thermistor 6 is also stopped, and the thermal actuator 5 returns to the return temperature and is restored to the original initial 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 cover member 72 to which the cover piece 8 is inserted and the movable piece 4 is joined from the inner surface side. The cover member 72 has a peripheral edge portion 92 formed on the peripheral edge of the exposed portion 83 of the cover piece 8 and an inner surface portion 93 formed continuously from the peripheral edge portion 92 on the inner surface side of the cover piece 8. The peripheral edge 92 holds the cover piece 8. An accommodation portion 94 for accommodating the movable piece 4 is formed inside the peripheral edge portion 92. The inner surface portion 93 is joined to the end surface 74 (see FIG. 1) of the resin base 71 by ultrasonic welding or the like.

  A protrusion 95 that protrudes toward the resin base 71 is formed on the inner surface 93 of the cover member 72. The protrusion 95 has a first protrusion 95a and a second protrusion 95b. The 1st protrusion part 95a and the 2nd protrusion part 95b are formed in step shape. The first protrusion 95a is fitted into the recess 73a of the resin base 71, and the second protrusion 95b is fitted into the opening 73b of the resin base 71, and is welded without a gap. When the resin base 71 and the cover member 72 are joined by ultrasonic welding or the like, the first projecting portion 95a of the cover member 72 constitutes a part of the side wall of the housing portion 73 and guides the thermally responsive element 5 ( (See FIG. 2, FIG. 3, etc.)

  An embedded portion 84 of the cover piece 8 is embedded in the protruding portion 95. The buried portion 84 is formed between the joint portion 82 of the cover piece 8 and the terminal 81. The embedded portion 84 has a first bent portion 84a and a second bent portion 84b. The embedded portion 84 is formed in a stepped step bent shape by the first bent portion 84a and the second bent portion 84b.

  The protrusion 95 of the cover member 72 is formed with an abutting portion 96 that protrudes from the side wall to the accommodating portion 94. As shown in FIG. 3, the abutting portion 96 abuts against the edge of the thermal response element 5 when the thermal response element 5 is thermally deformed, and regulates the posture of the thermal response element 5. In the present embodiment, at the time of energization shown in FIG. 2, the edge of the thermally responsive element 5 is separated from the contact part 96, but both may be always in contact.

  FIG. 5 shows how the cover member 72 is formed. The cover member 72 is formed by an injection molding process using the mold 300. The mold 300 includes a female mold 301 and a male mold 302. As shown in FIG. 5A, a cover piece 8 is inserted during injection molding. In the cover piece 8 to be loaded, a terminal 81, an embedded portion 84, and the like are already formed by pressing or the like.

  When the cover piece 8 is loaded into the mold 300 and a mold closing operation is performed between the female mold 301 and the male mold 302, as shown in FIG. 5B, the female mold 301 and the male mold A cavity space 303 defined by 302 is formed inside the mold 300. For example, a cavity space 303 for forming the protruding portion 95 is defined around the embedded portion 84.

  As shown in FIG. 5C, the cavity space 303 is filled with the resin material 304, and after cooling and curing, the mold is opened, and the cover member 72 with the cover piece 8 inserted is taken out. The resin material 304 filled in the cavity space 303 around the embedded portion 84 is cured to form the protruding portion 95 and the like. The resin material 304 is filled via a gate (not shown) formed in the female mold 301 or the male mold 302. In the present embodiment, the cover piece 8 is loaded into the mold 300 before the movable piece 4 is joined to the cover piece 8. Thereby, the shape of the male mold 302 can be simplified corresponding to only the cover piece 8, and the manufacturing cost of the mold 300 is reduced.

  FIG. 6 shows how the movable piece 4 is joined to the cover piece 8 of the cover member 72 and the cover member 72 is attached to the resin base 71. As shown in FIG. 6A, the embedded portion 84 of the cover piece 8 is embedded in the protruding portion 95 by the above-described injection molding process, and a contact portion 96 is formed on the side wall of the protruding portion 95. Yes.

  As shown in FIG. 6B, the movable piece 4 is joined to the inner surface of the cover piece 8. Both are joined at the joint 82 of the cover piece 8 and the joint 42 of the movable piece 4. Accordingly, as shown in FIG. 6C, the resin base 71, the cover piece 8, and the movable piece 4 are integrated. In this embodiment, the movable piece 4 is joined to the cover piece 8 by welding. However, if sufficient joining strength is obtained and sufficient conduction is obtained between the movable piece 4 and the cover piece 8. Other bonding forms may be applied. The cover piece 8 and the movable piece 4 may be joined before the insert molding shown in FIG. In this case, if the joining strength between the movable piece 4 and the cover piece 8 can be sufficiently obtained by the resin constituting the cover member 72, the joining of the cover piece 8 and the movable piece 4 by welding may be omitted. .

  Thereafter, as shown in FIG. 6D, the fixing piece 2 is embedded, and a cover member 72 is attached to the resin base 71 on which the PTC thermistor 6 and the thermal actuator 5 are mounted. The cover member 72 is joined by ultrasonic welding.

  FIG. 7 shows the breaker 1 in which the resin base 71 and the cover member 72 are joined. By the ultrasonic welding, the end surface 74 of the resin base 71 and the inner surface portion 93 of the cover member 72 are joined without a gap. The first protrusion 95a formed on the inner surface 93 of the cover member 72 is fitted into the recess 73a of the resin base 71, and the second protrusion 95b is fitted into the opening 73b of the resin base 71, respectively. There is no welding. Therefore, as indicated by a bold line in the figure, the resin base 71 and the cover member 72 are joined over the entire circumference outside the accommodating portion 73. Furthermore, the area where the resin base 71 and the cover member 72 are joined can be set large by the step-like first protrusion 95a and second protrusion 95b, and the recess 73a and opening 73b.

  As described above, according to the breaker 1 of the present embodiment, since the resin base 71 and the cover member 72 are joined over the entire circumference outside the housing portion 73, the internal space of the housing portion 73 is It is sealed and isolated from the outside of the breaker 1. As a result, the airtightness of the case 7 is enhanced, and it is possible to prevent adverse effects on the metal constituting the thermal reaction element 5, and the normal thermal deformation operation of the thermal reaction element 5 is maintained, and good temperature characteristics are obtained. Can do.

  According to the breaker 1, the cover member 72 includes a peripheral edge 92 formed on the periphery of the cover piece 8, and an inner surface 93 formed on the inner surface side of the cover piece 8 continuously from the peripheral edge 92. Since the inner surface portion 93 is joined to the resin base 71, the hermeticity of the accommodating portion 73 can be improved while reducing the height dimension of the breaker 1.

  According to the breaker 1, since the protruding portion 95 that protrudes toward the resin base 71 is formed on the inner surface portion of the cover member 72, the cover member 72 and the cover piece 8 are firmly joined at the protruding portion 95, The airtightness of the case 7 is further enhanced. Further, since the protruding portion 95 constitutes the side wall of the housing portion 73, the position and posture of the thermally responsive element 5 are stabilized, and good temperature characteristics are obtained.

  According to the breaker 1, the inner surface of the cover member 72 has the contact portion 96 that comes into contact with the heat responsive element 5 when the heat responsive element 5 is thermally deformed. The amount can be increased. Thereby, the stability of the electric current interruption operation by the breaker 1 can be enhanced without increasing the height dimension of the breaker 1.

  According to the breaker 1, since the cover piece 8 has the terminal 81 protruding from the cover member 72, it is not necessary to provide a terminal on the movable piece 4, so that the airtightness of the case 7 is further improved. Moreover, since the structure of the periphery of the movable piece 4 (especially the base end of the movable piece 4) is simplified, the freedom degree of design of the breaker 1 increases.

  According to the breaker 1, since the cover piece 8 has the joining part 82 to which the joining part 42 of the movable piece 4 is joined on the inner surface, the posture of the movable piece 4 is stabilized. Thereby, since the positional relationship between the fixed contact 21 and the movable contact 3 is stabilized, the resistance value during energization is stabilized and good temperature characteristics are obtained.

  According to the breaker 1, the cover piece 8 is embedded in the protruding portion 95 of the cover member 72 in the embedded portion 84 formed between the terminal 81 and the joint portion 82. The height of the movable piece 4 is further increased and the posture of the movable piece 4 is further stabilized.

  According to the breaker 1, since the joint portion 82 is provided in a region overlapping with the thermally responsive element 5 in plan view, the cover piece 8 and the cover member 72 can be reduced in size.

(Modification 1)
FIG. 8 shows a breaker 1 </ b> A that is a modification of the breaker 1. In the breaker 1A, the heights of the terminal 22 and the terminal 81 with respect to the case 7 are changed. In the breaker 1 </ b> A, the terminal 22 extends on the same plane as the fixed contact 21. The terminal 81 protrudes from the bottom surface of the resin base 71 at the same height as the terminal 22. Accordingly, the second bent portion 84b of the embedded portion 84 is moved upward in the drawing, and the second protruding portion 95b of the protruding portion 95 and the opening 73b of the resin base 71 are omitted. According to this modification, the height of the terminal 22 and the terminal 81 relative to the case 7 can be adjusted according to the specifications of the secondary battery circuit and the safety circuit. Moreover, since the area of the junction part of the protrusion part 95 and the resin base 71 increases compared with the breaker 1, the airtightness of the case 7 is further improved.

(Modification 2)
FIG. 9 shows a breaker 1 </ b> B that is another modification of the breaker 1. In the breaker 1B, the height of the terminal 22 and the terminal 81 with respect to the case 7 is changed. In the breaker 1B, the height of the terminal 22 is equal to that of the breaker 1A, but may be equal to that of the breaker 1. In the breaker 1 </ b> B, the terminal 81 extends on the same plane as the top surface of the cover member 72. Accordingly, the exposed portion 83 is expanded to the terminal 81, and the first bent portion 84a and the second bent portion 84b are omitted. According to this modification, the height of the terminal 81 relative to the case 7 can be adjusted according to the specifications of the secondary battery circuit and the safety circuit.

(Modification 3)
FIG. 10 shows a breaker 1 </ b> C that is another modification of the breaker 1. In the breaker 1 </ b> C, the shapes of the terminal 22 and the terminal 81 are changed. In the breaker 1 </ b> C, the terminal 22 and the terminal 81 are bent in a U-shaped cross section and are disposed on the same plane as the bottom surface of the resin base 71. The end face of the tip of the terminal 22 is embedded in the resin base 71, and the end face of the tip of the terminal 81 is embedded in the second projecting portion 95 b of the cover member 72. According to this modification, the breaker can be further reduced in size.

(Modification 4)
FIG. 11 shows a breaker 1 </ b> D that is still another modified example of the breaker 1. In the breaker 1D, the movable piece 4 and the cover piece 8 are integrally formed by pressing a single metal plate. In this modified example, the movable piece 4 is formed inside the cover piece 8 by folding the metal plate at the folded portion 85. The position and form of the folded portion 85 are not limited to those shown in FIG. 11 and can be set as appropriate (see FIG. 12 described later). Further, the top surface of the cover piece 8 can function as the terminal 81.

(Modification 5)
FIG. 12 shows a breaker 1 </ b> E that is still another modified example of the breaker 1. Similarly to the breaker 1D, the breaker 1E is integrally formed by pressing the movable piece 4 and the cover piece 8 on a single metal plate. In this modified example, the metal plate is bent at the first bent portion 85a and the second bent portion 85b, whereby the cover piece 8 is formed around and inside the protruding portion 95, and the cover piece 8 A movable piece 4 is formed inward. In the breaker 1E, a terminal 81 is formed between the fourth bent portion 85b and the second bent portion 84b. The terminal 81 is disposed on the same plane as the bottom surface of the resin base 71.

  In addition, this invention is not restricted to the structure of the said embodiment, The resin base 71 and the cover member 72 should just be joined over the perimeter outside the accommodating part 73 at least.

  For example, instead of the terminal 81 of the cover piece 8, the movable piece 4 may be extended to the protruding portion 95 side and protrude from the cover member 72 to constitute the terminal. In this case, the movable piece 4 and the cover piece 8 are inserted into the mold to form the cover member 72. Further, the movable piece 4 and the cover piece 8 may be joined via a resin constituting the cover member 72, and welding between them may be omitted.

  Further, the movable piece 4 may be extended to the terminal 81 side, and the joint portion 42 may be formed inside the protruding portion 95.

  Further, a protrusion may be provided on the inner surface of the cover piece 8 in place of the contact portion 96, and this protrusion may be configured to contact the edge of the thermally responsive element 5 during thermal deformation. Further, the joint portion 42 of the movable piece 4 may be extended in the longitudinal direction of the breaker 1, and a projection that contacts the edge of the thermally responsive element 5 during thermal deformation may be formed on the joint portion 42.

  The cover member 8 may be formed by mounting the cover piece 8 on the resin base 71 and inserting them into the mold.

  Further, the entire top surface of the cover piece 8 may be covered with a resin constituting the cover member 72.

  Moreover, the joining method of the resin base 71 and the cover member 72 is not limited to ultrasonic welding, and any method can be applied as long as both are firmly joined and sufficient airtightness is obtained. For example, a liquid or gel adhesive may be applied, filled, and cured to bond them together. Further, the case 7 is not limited to the form constituted by the resin base 71 and the cover member 72, but may be any form constituted by two or more parts. In this case, one is the first case and the other is the second case.

  Further, the shapes of the movable piece 4, the resin base 71, and the cover member 72 are not limited to those shown in FIG. Further, the shapes of the thermally responsive element 5 and the accommodating portion 73 are not limited to those shown in FIG. 1 and the like, and can be appropriately changed.

  Further, the number of protrusions provided on the support portion 23 is not particularly limited. For example, another protrusion may be added to a location adjacent to the fixed contact 21, the center portion of the support portion 23, or the like. Furthermore, the structure which arrange | positions another component between the PTC thermistor 6 and the fixed piece 2 may be sufficient. In this case, the support portion 23 supports the PTC thermistor 6 via the separate part. Moreover, in the support part 23, one part or all protrusions may be abbreviate | omitted.

  Moreover, the structure which forms the movable piece 4 and the thermally responsive element 5 integrally by forming the movable piece 4 with a bimetal or a trimetal etc. may be sufficient. In this case, the configuration of the breaker is simplified, and further miniaturization can be achieved.

  Further, the breaker 1 of the present invention can be widely applied to secondary battery packs, safety circuits for electric devices, and the like. FIG. 13 shows the secondary battery pack 100. The secondary battery pack 100 includes a secondary battery 101 and a breaker 1 provided in the output terminal circuit of the secondary battery 101. FIG. 14 shows a safety circuit 102 for electrical equipment. The safety circuit 102 includes a breaker 1 in series in the output circuit of the secondary battery 101.

DESCRIPTION OF SYMBOLS 1 Breaker 2 Fixed piece 3 Movable contact 4 Movable piece 5 Thermally responsive element 7 Case 8 Cover piece 71 Resin base (1st case)
72 Cover member (second case)
73 Housing portion 81 Terminal 82 Joint portion 92 Peripheral portion 93 Inner surface portion 95 Projecting portion 96 Abutting portion 101 Secondary battery 102 Safety circuit

Claims (9)

A fixed piece having a fixed contact;
A movable piece having a movable contact, and pressing the movable contact against the fixed contact;
A thermally responsive element that operates the movable piece so that the movable contact is separated from the fixed contact by being deformed with a temperature change;
A first case having an accommodating portion for accommodating the thermally responsive element;
In a breaker comprising a second case attached to the first case,
The second case includes an inner surface joined to the first case, a first projecting portion projecting from the inner surface in the direction of the first case, and a second projecting from the first projecting portion in the direction. Having a protrusion,
The first protrusion and the second protrusion are in close contact with the first case,
The breaker characterized in that the first case and the second case are joined over the entire circumference outside the housing portion. A cover piece formed integrally with the second case;
2. The breaker according to claim 1 , wherein the cover piece has an embedded portion embedded in the second case in a region including the first protruding portion and the second protruding portion . The breaker according to claim 2, wherein the embedded portion is formed with a bent portion bent in a stepped manner . The inner surface portion of the second case is provided with an abutting portion that abuts the thermal responsive element when the thermal responsive element is thermally deformed .
The breaker according to any one of claims 1 to 3 , wherein the contact portion, the first protruding portion, and the second protruding portion are formed in a step shape . The cover piece includes a terminal protruding from the second case , and a joint portion to which a part of the movable piece is joined,
The breaker according to claim 3 , wherein the bent portion is disposed between the terminal and the joint portion . The said 1st protrusion part is a breaker as described in any one of Claims 1 thru | or 5 which comprises the side wall of the said accommodating part . The breaker according to any one of claims 1 to 5, wherein the second projecting portion is fitted with an opening that penetrates the first case and forms a part of an outer wall . A safety circuit for an electric device comprising the breaker according to any one of claims 1 to 7. A secondary battery circuit comprising the breaker according to any one of claims 1 to 7.

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