JP2014059999A - Breaker and safety circuit equipped with the same, and secondary battery circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good temperature characteristics by preventing rust of a thermally-actuated element on a breaker used as a protective device for a secondary battery or the like.SOLUTION: A movable piece 4 includes a terminal 41 projecting outside a plastic case 7, an elastic part 43 exerting an elastic force to press a movable contact 3 against a fixed contact 21 and an abutting portion 42 abutting the plastic case 7 between the terminal 41 and the elastic part 43. A resin coating 42d is formed on the front and back sides of the abutting portion 42. The resin coating 42d is tightly bound to the abutting portion 42 without a gap. The resin coating 42d and the plastic case 7 are tightly bound by welding or the like. As a result, the adhesion between the movable piece 4 and the plastic case 7 is increased, water or the like is prevented from entering into the inside of the plastic case 7, rust on a thermally-actuated element is prevented and normal thermal deformation is kept.

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 this document is a fixed piece (base terminal), a movable piece (movable arm), a thermal actuator, a PTC thermistor, etc. housed in a resin case. Is used by being connected to an electric circuit of an electric device.

  In the breaker disclosed in Patent Document 1, the lid member is ultrasonically welded to the case body to integrate the resin case, and the movable piece is fixed to the lid member (cover member) at the fixed portion (contact portion). The case body (resin base) is sandwiched from both the front and back surfaces, and the posture of the movable piece is fixed (see paragraphs (0032) and (0037) of the same document).

WO2011 / 105175 gazette

  In Patent Document 1, since the case main body and the lid member constituting the resin case are both formed of a resin material, they are firmly bonded to each other by ultrasonic welding, and high welding strength and airtightness (sealing) between them. Property). On the other hand, the movable piece which comprises an electric circuit with a fixed piece is formed with the metal material. Since the bond between the metal material and the resin material is inferior to the bond between the resin materials, the welding strength may be reduced or the airtightness may be reduced between the two. For this reason, depending on the extremely inferior use environment, moisture may enter the internal space, and rust may be generated in the metal constituting the thermal response element, etc., and the normal thermal deformation operation of the thermal response element is hindered by the rust. There was a fear.

  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 through a slight gap generated between the movable piece, the case main body, and the lid member, which contributes to the rust described above.

  The present invention has been made to solve the above-mentioned problems, and improves the welding strength and airtightness between the movable piece and the resin case, thereby preventing the rust of the thermal responsive element and the like to be normal. An object of the present invention is to provide a breaker capable of maintaining a heat deformation operation and obtaining good temperature characteristics.

  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. 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 movable piece includes a terminal projecting outside the resin case, an elastic part that generates an elastic force for pressing the movable contact against the fixed contact, and the resin case between the terminal and the elastic part. And a resin film is formed on the contact portion.

  In this invention, it is preferable that the resin film is formed on a surface facing the thermoresponsive element.

  In the present invention, it is preferable that the resin coating is formed on a surface opposite to the surface facing the thermoresponsive element.

  In this invention, it is preferable that the resin coating is continuously formed at least partially from one end to the other end of the contact portion in a direction perpendicular to the direction in which the elastic portion extends. preferable.

  In the present invention, it is preferable that the resin film is formed so as to avoid a contact portion with the thermally responsive element.

  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, the gap between the contact portion and the resin case is filled with the resin film formed on the contact portion, and the airtightness between the movable piece and the resin case is improved. Further, the resin film can be formed on the outer surface of the movable piece by a technique such as printing or coating, and can be extremely firmly adhered to the movable piece without any gap. And since a resin film and a resin case are mutually resin, it couple | bonds firmly by ultrasonic welding. Therefore, the bonding strength in the region from the movable piece to the resin case is increased, and extremely high sealing performance is obtained. This prevents moisture and flux from penetrating into the resin case, prevents rust from occurring in metal parts such as the thermal actuator, and maintains the normal thermal deformation operation of the thermal actuator, Good temperature characteristics can be obtained.

  In addition, according to the configuration in which the resin film is formed on the surface facing the thermal response element, it is possible to effectively prevent moisture and the like from adhering to the outer surface of the thermal response element, and rust is generated in the thermal response element. This can be prevented directly.

  In addition, according to the configuration in which the resin film is formed on the surface opposite to the surface facing the thermal response element, moisture or the like can be prevented from entering from the surface opposite to the thermal response element. It is possible to further improve the welding strength and airtightness between the resin case and the resin case.

  In addition, according to the configuration in which the resin coating is continuously formed from one end to the other end of the abutting portion, the sealing performance of the resin case is further improved, and the penetration of moisture and the like into the resin case is prevented. it can.

  In addition, according to the configuration in which the resin film is formed so as to avoid the contact portion with the heat-responsive element, the movable piece and the heat-responsive element are in direct contact with each other. Does not hinder. Further, in the breaker configured to provide the self-holding circuit function, conduction between the movable piece and the thermally responsive element at the time of interruption can be ensured.

  Moreover, according to the safety circuit or the secondary battery pack provided with the breaker of the present invention, the safety circuit or the secondary battery pack in which safety is ensured by excellent temperature characteristics can be manufactured.

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 structure of the movable piece applied to the breaker. The perspective view which shows the process of forming a resin film in the base material of the movable piece. The perspective view which shows the process of shape | molding the movable piece from the base material. The perspective view which shows the modification of the breaker. Sectional drawing which shows a mode that a movable piece is integrated in the resin base and a cover member is mounted | worn in the modification. 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, and a resin case 7 that accommodates a PTC thermistor 6. The resin case 7 includes a resin base (first case) 71, a cover member (second case) 72 mounted on 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 PTC thermistor 6 is placed in the vicinity of the other end. The PTC thermistor 6 is placed on convex dowels (small protrusions) 23 a formed at three locations in the vicinity of the other end 23 of the fixed piece 2. 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 73b formed above. The terminal 22 protrudes outward from one end of the resin base 71.

  The movable piece 4 is formed in an arm shape symmetrical to the center line in the longitudinal direction by pressing a metal plate equivalent to the fixed piece 2. 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. A terminal 41 electrically connected to an external circuit is formed at one end in the longitudinal direction of the movable piece 4 and protrudes outward from the resin base 71. In this embodiment, in order to make the height of the terminal 22 of the fixed piece 2 and the terminal 41 of the movable piece 4 uniform, the movable piece 4 is bent in a crank shape at a step bending portion 46 formed outside the resin case 7. Has been. 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 made of the same material as the fixed contact 21 and is joined to the tip of the movable piece 4 by a technique such as welding. In the present application, in the movable piece 4, the surface to which the movable contact 3 is joined (that is, the lower surface in FIG. 1) is the back surface, and the opposite surface is the front surface. It is described as a surface. The movable piece 4 has a contact 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, which contact the resin base 71 and the cover member 72. Yes. The contact portion 42 has a protruding portion 42 a that protrudes in a wing shape in the short direction of the movable piece 4 between the terminal 41 and the elastic portion 43. The elastic part 43 extends from the contact part 42 to the movable contact 3 side. The movable piece 4 is fixed by being sandwiched between the resin base 71 and the cover member 72 at the contact portion 42, and the elastic portion 43 is elastically deformed, so that the movable contact 3 formed at the tip of the elastic portion 43 is moved to the fixed contact 21 side. The fixed piece 2 and the movable piece 4 can be energized by being pressed and contacted.

  The resin base 71 and the cover member 72 are respectively formed with an abutting portion 74 and an abutting portion 79 that abut against the abutting portion 42 of the movable piece 4 and hold the abutting portion 42 in a fixed state. In the present embodiment, a contact portion 74 is formed in a region extending from the outer edge of the housing portion 73 of the resin base 71 to the outer wall of the resin base 71. In the cover member 72, a contact portion 79 is formed in a region facing the contact portion 74 with the movable piece 4 interposed therebetween. The contact portion 42 contacts the contact portion 74 of the resin base 71 on the back surface, and contacts the contact portion 79 of the cover member 72 on the front surface. The movable piece 4 is sandwiched from both the front and back surfaces of the contact portion 42 by the contact portion 74 and the contact portion 79 and fixed to the resin case 7. In this embodiment, since the contact part 42 has the protrusion part 42a which protrudes in a wing shape in the transversal direction of the movable piece 4, the contact part 42 and the contact part 74 and the contact part of the resin case 7 are wide in a large area. Since it is sandwiched between the portions 79, the movable piece 4 is firmly fixed to the resin case 7.

  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 pair of small protrusions (contact portions) 44 are formed on the lower surface of the elastic portion 43 so as to face the heat-responsive element 5. The small protrusion 44 and the thermal response element 5 come into contact with each other, and the deformation of the thermal response element 5 is transmitted to the elastic portion 43 through the small protrusion 44 (see FIGS. 1, 2, and 3).

  Further, the movable piece 4 penetrates in the thickness direction of the movable piece 4, and the through hole 45 through which the protrusion 74 a of the resin base 71 is inserted, the stepped bent portion 46 formed in a crank shape, and the length of the movable piece 4. A constricted portion 49 is formed in which a part of the movable piece 4 is cut in a short direction perpendicular to the direction. The through hole 45, the step bent portion 46, and the constricted portion 49 are provided on the opposite side of the movable contact 3 with the elastic portion 43 interposed therebetween, that is, on the terminal 41 side with respect to the elastic portion 43. The through hole 45 is provided on the center line in the longitudinal direction of the movable piece 4 at the constricted portion 49. The step bent portion 46 is formed outside the resin case 7 and in the vicinity of the base of the terminal 41. The constricted portion 49 is formed in the vicinity of the edge of the resin case 7. The through hole 45 and the constricted portion 49 constitute the second elastic portion described in Patent Document 1.

  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. As described above, when rust is generated in the thermal response element 5, the physical properties of the metal constituting the thermal response element 5 change, so that the reverse warpage deformation does not occur even when the operating temperature is exceeded, and the normal current generated by the breaker There is a possibility that the blocking function is disturbed. Therefore, in the breaker 1 of the present embodiment, the sealing performance of the resin case 7 is improved and the rust of the thermally responsive element 5 is prevented.

  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 shape is not particularly limited as long as these properties are not impaired.

  The resin base 71 and the cover member 72 constituting the resin case 7 are formed of a resin such as flame retardant polyamide, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), or polybutylene terephthalate (PBT) having excellent heat resistance. ing. The resin base 71 is formed with a housing portion 73 for housing the thermally responsive element 5, the PTC thermistor 6, and the like, and openings 73 a and 73 b for housing the movable piece 4. Note that the edges of the movable piece 4, the thermally responsive element 5, and the PTC thermistor 6 incorporated in the resin base 71 are in contact with each other by a frame formed inside the opening 73, so that the thermal responsive element 5 is reversely warped. It is guided at times.

  The resin base 71 has a projection 74a inserted into the through hole 45 of the movable piece 4, a pair of positioning portions 75 for positioning the movable piece 4, and a terminal 41 for exposing the movable piece 4 to the outside. A window 76 is provided. The protrusion 74 a is formed in a shape corresponding to the through hole 45 and reinforces the resin base 71. The height of the projection 74a, that is, the projection amount is set to be larger than the thickness of the movable piece 4, and a concave portion corresponding to the top of the projection 74a is provided on the back surface of the cover member 72 as necessary. The positioning portion 75 is provided in a shape corresponding to the constricted portion 49 of the movable piece 4. That is, the positioning portion 75 is interposed in a portion cut out in the vicinity of the constricted portion 49, reinforces the resin base 71, and is welded to the abutting portion 79 of the cover member 72 to increase the rigidity and strength of the resin case 7. Increase.

  A cover piece 8 is embedded in the cover member 72 by insert molding. 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. As shown in FIGS. 2 and 3, the cover piece 8 is in contact with the upper surface of the movable piece 4 as appropriate to restrict the movement of the movable piece 4, and the cover member 72 and the rigidity of the resin case 7 as a casing are also provided. Contributes to downsizing of breaker 1 while increasing strength.

  As shown in FIG. 1, a cover member 72 is formed on the upper surface of the resin base 71 so as to close the opening 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. Installed. 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 thermal responsive element 5 maintains the initial shape (before reverse warping), the fixed contact 21 and the movable contact 3 come into contact with each other, and the breaker 1 passes through the elastic portion 43 of the movable piece 4. The terminals 22 and 41 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 configuration of the movable piece 4. In the figure, (a) shows the front side of the movable piece 4, and (b) shows the back side of the movable piece 4. The movable piece 4 includes a terminal 41 projecting outside the resin case 7, an elastic portion 43 that generates an elastic force for pressing the movable contact 3 against the fixed contact 21, and the terminal 41 and the elastic portion 43. A contact portion 42 that contacts the resin case 7 is provided. In FIG. 4A, the surface of the contact portion 42 indicated by hatching (the surface opposite to the surface facing the thermal actuator 5) 42b is in contact with the contact portion 79 of the cover member 72 and in FIG. The back surface 42c of the contact portion 42 indicated by hatching (the surface facing the thermally responsive element 5) 42c contacts the contact portion 74 of the resin base 71, respectively. In the present embodiment, a resin coating 42d made of a resin material such as polyamideimide is formed on the front surface 42b and the back surface 42c of the contact portion 42. The thickness of the resin coating 42d is, for example, from several μm to several tens of μm. Resin materials such as polyamideimides have heat resistance against lead-free solder mounting.

  The resin material used for the resin coating 42d is not particularly limited depending on the compatibility with the metal material used for the movable piece 4 and the resin material used for the resin base 71 and the cover member 72. More specifically, the resin material used for the resin coating 42d may include a primer used as a base for painting such as epoxy and acrylic. The resin coating 42d has a configuration in which a primer and a resin paint are laminated, a configuration in which a primer is applied to the resin base 71 and the cover member 72 on the movable piece 4, or a resin base 71 and a cover member 72. The resin material used may be melted and firmly bonded to the primer on the movable piece 4 side. Further, the physical form of the resin coating 42d formed on the movable piece 4 is not limited, such as a coating or printing of the above material and drying or baking. That is, the resin material used for the resin coating 42d is not particularly limited as long as it is a substance that enhances the affinity between the metal material used for the movable piece 4 and the resin material used for the resin base 71 and the cover member 72.

  5 and 6 show the manufacturing process of the movable piece 4. As shown in FIG. 5A, the movable piece 4 is formed from a base material 40 of a metal plate whose main component is phosphor bronze or the like. As shown in FIG. 5B, a resin coating 42 d is formed in a region corresponding to the contact portion 42 in the base material 40. The resin coating 42 d is formed on the front and back surfaces of the base material 40 by applying or printing a resin material on the front and back surfaces of the base material 40. The resin coating 42 d is formed continuously in the width direction of the base material 40. And as shown to Fig.6 (a), the movable piece 4 is cut out from the base material 40 by press work. At this time, a terminal 41, a contact portion 42, an elastic portion 43, a small protrusion 44, a through hole 45, a step bending portion 46, a constricted portion 49, and the like are formed on the movable piece 4, and the movable contact 3 is provided at the tip of the elastic portion 43. Is formed. At this stage, the terminal 41 is integrally connected to the carrier 40 a, and the movable piece 4 can be conveyed and properly aligned with the resin base 71 by gripping the carrier 40 a. Then, as shown in FIG. 6B, when the terminal 41 is cut from the carrier 40a, the engagement between the through hole 45 and the protrusion 74a and the relationship between the end edge of the abutting portion 42 protruding portion 42a and the side wall of the opening 73a. As a result, the movable piece 4 is accurately guided and placed on the resin base 71. Thereafter, the cover member 72 is attached to the resin base 71, and the resin base 71 and the cover member 72 are joined by ultrasonic welding. 5 and 6, the manufacturing process of one movable piece 4 has been described. However, as disclosed in, for example, Japanese Patent No. 3341167, a plurality of movable pieces 4 connected via a carrier 40a are provided. By using this, the breaker 1 may be mass-produced efficiently. In this case, the base material 40 and the resin coating 42d are continuously formed in the direction in which the plurality of movable pieces 4 are arranged.

  The resin coating 42d formed on the front and back surfaces of the metal plate constituting the movable piece 4 by applying or printing the resin material is firmly adhered to the front and back surfaces of the metal plate and does not easily peel off. Further, since the resin coating 42d, the resin base 71, and the cover member 72 are both made of a resin material, they are firmly bonded by ultrasonic welding. As a result, the bonding strength in the region from the movable piece 4 to the resin case 7 is increased, and the movable piece 4 and the resin case 7 are firmly adhered.

  The resin coating 42d is continuously formed over the entire surface 42b and back 42c of the contact portion 42. Accordingly, no gap is generated between the contact portion 42 of the movable piece 4, the contact portion 74 of the resin base 71 and the contact portion 79 of the cover member 72, and the sealing performance of the resin case 7 is improved. Here, that the resin coating 42d is continuously formed over the entire surface 42b and the back surface 42c of the contact portion 42 means that the metal material constituting the movable piece 4 and the resin material constituting the resin case 7 are formed. It means that it is continuously formed over the entire surface in the part to be joined by welding. Therefore, even if the continuity of the resin film 42d is partially cut off by the through hole 45 provided in the contact portion 42 as in the present embodiment, the top portion of the protrusion 74a inserted through the through hole 45 and the cover member The abutting portion 79 of 72 is firmly bonded without a gap by welding of the resins. For this reason, the deterioration of the sealing property of the resin case 7 due to the provision of the through hole 45 in the contact portion 42 does not occur. Further, since the resin material of the protrusion 74a and the positioning portion 75 melts and flows into the side wall (end surface) of the through hole 45 and the side wall of the constricted portion 49, the sealing performance of the resin case 7 does not deteriorate as described above. . The resin film 42d formed on the contact portion 42 of the movable piece 4 can be confirmed by separating the cover member 72 from the resin base 71 in the completed breaker 1.

  Further, the resin coating 42 d is formed on the terminal 41 side with respect to the small protrusion 44 formed on the elastic portion 43. That is, the resin coating 42d is formed so as to avoid the small protrusions 44 that come into contact with the thermally responsive element 5. As a result, the small protrusion 44 of the movable piece 4 and the thermally responsive element 5 are in direct contact with each other without the resin film 42d interposed therebetween, so that the resin film 42d conducts heat conduction between the movable piece 4 and the thermally responsive element 5. Does not hinder. Further, in the breaker 1 having a self-holding circuit function by the PTC thermistor 6 described above, conduction between the movable piece 4 and the thermally responsive element 5 can be ensured in the shut-off state shown in FIG.

  As described above, according to the breaker 1 of the present embodiment, the gap between the contact portion 42 and the resin case 7 is filled with the resin coating 42d formed on the contact portion 42, and the movable piece 4 and the resin The airtightness between the case 7 and the case 7 is improved. Further, the resin coating 42d can be formed on the outer surface of the movable piece 4 by a technique such as printing or application, and can be extremely firmly adhered to the movable piece 4 without a gap. Since the resin coating 42d and the resin case 7 are made of resins, they are firmly bonded by ultrasonic welding. Therefore, the bonding strength in the region from the movable piece 4 to the resin case 7 is increased, and extremely high sealing performance is obtained. Thereby, it is possible to prevent moisture and flux from entering the resin case 7 and to prevent rust from being generated on the metal parts such as the heat responsive element 5, and to perform normal heat deformation operation of the heat responsive element 5. Can be maintained and good temperature characteristics can be obtained.

  In addition, since the resin coating 42d is formed on the surface facing the thermal response element 5, it is possible to effectively prevent moisture and the like from adhering to the outer surface of the thermal response element 5, and rust is generated in the thermal response element 5. Can be prevented directly.

  Further, since the resin coating 42d is formed on the surface opposite to the surface facing the thermal response element 5, it is possible to prevent moisture and the like from entering from the surface opposite to the thermal response element 5. 4 and the resin case 7 can be further improved in welding strength and airtightness.

  Further, since the resin coating 42d is continuously formed over the entire surface of the abutting portion 42, the sealing property of the resin case 7 is further enhanced, and the entry of moisture and the like into the resin case 7 can be prevented.

  Further, since the resin coating 42d is formed so as to avoid the small protrusions 44 that come into contact with the thermal response element 5, the movable piece 4 and the thermal response element 5 are in direct contact, and the resin coating 42d is between them. Does not interfere with heat conduction. Further, in the breaker 1 having the PTC thermistor 6 and having a self-holding circuit function, the conduction between the movable piece 4 and the thermally responsive element 5 at the time of interruption shown in FIG. 3 can be ensured.

(Modification)
FIG. 7 shows a breaker 1 </ b> A that is a modification of the breaker 1. The breaker 1 </ b> A is different from the breaker 1 in that the step bent portion 46 of the movable piece 4 </ b> A is disposed inside the resin case 7. In FIG. 7, the point that the resin coating 42d is formed on both the front and back surfaces of the abutting portion 42 indicated by hatching of the movable piece 4A is the same as that of the breaker 1. Further, as the through hole 45 is changed to a long hole, the shape of the protrusion 74a is also changed. The movable piece 4 </ b> A includes a slope 47 and an engaging portion 48. The inclined surface 47 is continuously formed along the direction of the movable piece 4A at the stepped bending portion 46, and the engaging portion 48 extends from the constricted portion 49 to the terminal 41 at two locations along the short direction of the movable piece 4A. It is provided and engaged with the positioning portion 75 of the resin base 71.

  In the breaker 1 </ b> A, the stepped portion 46 of the movable piece 4 </ b> A is disposed inside the resin case 7, and the contact portion 74 of the resin base 71 is formed in a step shape corresponding to the stepped bent portion 46. The Further, the cover member 72 is formed with a step portion 77 protruding from the inner wall surface thereof into a shape corresponding to the step bending portion 46 of the movable piece 4A, and an inclined surface 78 (see FIG. 8) formed on the step portion 77. . The slope 78 corresponds to the slope 47 of the movable piece 4A, and is formed continuously along a direction perpendicular to the longitudinal direction of the movable piece 4A.

  FIGS. 8A and 8B show in time series how the movable piece 4A is incorporated in the resin base 71 and the cover member 72 is attached and welded. The movable piece 4 </ b> A is guided into the openings 73 a and 73 b of the resin base 71 and incorporated into the resin base 71. At this time, as shown in FIG. 7, the positioning portions 75 are engaged with the engaging portions 48 on both sides of the constricted portion 49 formed on the movable piece 4 </ b> A, and the protrusions 74 a of the resin base 71 are formed in the through holes 45. It is inserted. Further, in addition to the protrusion 74a being inserted into the through hole 45, the engagement of the pair of engaging portions 48 and the pair of positioning portions 75 restricts the rotation of the movable piece 4A with respect to the resin base 71. Is easily done.

  In this temporary alignment stage, it is not necessary that the movable piece 4A is accurately aligned with the resin base 71. Further, the movable piece 4A is placed on the resin base 71 so as to be finally aligned in a later process, and is not fixed. The positions, shapes, dimensions, and the like of the openings 73a and 73b and the protrusions 74a of the resin base 71 are such that it is easy to guide the movable piece 4A from the position where provisional alignment has been performed to a fixed position where it is completely positioned. It is formed in a similar shape to the corresponding part of the movable piece 4A.

  As shown in FIG. 8A, after the movable piece 4 </ b> A is incorporated into the resin base 71, the cover member 72 is attached to the resin base 71. The cover member 72 is attached to the resin base 71 while inserting the stepped portion 77 into the opening 73a of the resin base 71 and pressing the stepped portion 77 against the stepped bent portion 46 of the movable piece 4A while positioning the movable piece 4A. Is done.

  As shown in FIG. 8B, when the cover member 72 is pressed in the direction of the resin base 71 (in the direction of the white arrow in the figure), the slope 47 of the movable piece 4A and the slope 78 of the cover member 72 come into contact with each other. . Since the inclined surface 47 and the inclined surface 78 are continuously formed along a direction perpendicular to the longitudinal direction of the movable piece 4A, when the cover member 72 is still pressed in the direction of the resin base 71, the movable piece The slope 47 of 4A is pushed (biased) by the slope 78 of the cover member 72 in the longitudinal direction of the movable piece 4A. As a result, the direction of the force is changed by the inclined surfaces 78 and 47, and the entire movable piece 4A is pushed and moved in the longitudinal direction, that is, the arrow A direction where the fixed piece 2 exists. At this time, the pair of engaging portions 48 disposed facing the slope 47 and the pair of positioning portions 75 disposed facing the slope 78 are brought into contact with each other and engaged. As a result, the movable piece 4 </ b> A that has been temporarily aligned by the protrusion 74 a and the like is accurately positioned with respect to the resin base 71. That is, the error at the time of temporary alignment that occurs when the movable piece 4A is incorporated into the resin base 71 is reduced, and the positioning error of the movable piece 4A with respect to the resin base 71 is substantially reduced by the positioning of the resin base 71. The dimensional error can be kept to the extent of the manufacturing of the engaging portion 48 of the portion 75 and the movable piece 4A.

  When the cover member 72 is attached to the resin base 71 and is ultrasonically welded, the tips of the protrusions 74a of the resin base 71 are brought into contact with and joined to the inner wall surface of the cover member 72. Accordingly, the movable piece 4 </ b> A is firmly joined from above and below by the resin base 71 and the cover member 72 around the through hole 45, that is, in the contact portion 42. Accordingly, the movable piece 4A is fixed at a fixed position (position where it should be) with respect to the resin base 71. Even after the cover member 72 is welded to the resin base 71 and the movable piece 4A is fixed, the slope 47 and the slope 78 remain in contact with each other, and the movable piece 4A continues to be pushed in the direction of arrow A. Accordingly, the positioning portion 75 and the engaging portion 48 maintain the engaged state, and the position and posture of the movable piece 4A with respect to the resin base 71 are maintained normally.

  When ultrasonic vibration is applied to either one or both of the resin base 71 and the cover member 72 while the cover member 72 is attached to the resin base 71 and the resin base 71 is pressed in the direction of the cover member 72, the resin base 71 The contact portion of 71 and cover member 72 (mainly the peripheral portion of resin base 71 and cover member 72) is welded by frictional heat, and resin base 71 and cover member 72 are integrated to form resin case 7. .

  According to the breaker 1A, the resin film 42d is formed on the abutting portion 42 of the movable piece 4A, so that the same effect as the breaker 1 can be obtained. Furthermore, the posture of the movable piece 4 </ b> A with respect to the resin base 71 is stabilized by the accurate positioning action by the inclined surface 47 and the inclined surface 78 and the engaging portion 48 and the positioning portion 75. Therefore, variation in the relative positional relationship between the movable contact 3 and the fixed contact 21 provided at the tip of the movable piece 4A is suppressed, and even better temperature characteristics can be obtained.

  The present invention is not limited to the configuration of the above embodiment, and a resin coating 42d is formed on the contact portion 42 that contacts the resin case 7 at least between the terminal 41 such as the movable piece 4 and the elastic portion 43. Just do it.

  The present invention can be modified in various ways. For example, the resin coating 42d may be formed on either the front surface 42b or the back surface 42c of the contact portion 42 such as the movable piece 4. Further, the resin coating 42d is not limited to the form formed over the entire surface of the contact portion 42, and at least a part thereof is perpendicular to the width direction of the movable piece 4 or the like (the direction in which the elastic portion 43 extends). In other words, the contact portion 42 may be formed continuously from one end to the other end of the contact portion 42 in any direction. This is because even if part of the contact portion 42 is formed continuously from one end to the other end, the internal space of the resin case 7 can be shielded from the outside to prevent intrusion of moisture, flux, and the like. .

  In addition, a resin film may be formed on the front surface and / or the back surface of the fixed piece 4. In this case, the resin coating is particularly effective when trying to improve the sealing performance of the resin case 7 in a structure in which a part of the fixed piece 4 is welded to the resin base 71 and / or the cover member 72. Furthermore, in a structure in which other metal parts such as a cover piece constituting the breaker are extended from the housing part inside the resin case and a part thereof is welded to the resin case, the part is welded to the resin case. A resin film may be formed. That is, the boundary of each part in the region from the housing part inside the resin case to the outside is filled with the resin material around the metal material by insert molding, and the resin film is formed on the metal material without a gap. The structure which is comprised by the form etc. which the resin material or the resin material welded without the clearance gap etc., and the whole accommodating part is sealed from the exterior of the resin case is preferable.

  Moreover, in FIG. 1 etc., the movable piece 4 is a form which has the structure of the through-hole 45, the step bending part 46, and the constriction part 49, However, Any or all of these structures may be abolished. . For example, when the through hole 45 is discarded, the projection 74a of the resin base 71 is also discarded. Moreover, when the step bending part 46 is abolished, the terminal 41 becomes a flat shape. In this configuration, by eliminating the step bending portion 46, the longitudinal dimension of the movable piece 4 and the resin base 71 can be reduced, and the breaker 1 can be further reduced in size. Further, when the constricted portion 49 is eliminated, the movable piece 4 is formed to have a uniform width from the contact portion 42 to the terminal 41, and the shape of the positioning portion 75 of the resin base 71 is changed accordingly. As described above, the shapes of the contact portion 42 of the movable piece 4, the contact portion 74 of the resin base 71, the contact portion 79 of the cover member 72, and the like are not limited to those shown in FIGS. It can be changed. Further, the shapes of the thermally responsive element 5 and the accommodating portion 73 are not limited to those shown in FIGS. 1 and 7 and can be appropriately changed.

  Moreover, the joining method of the resin base 71 and the cover member 72 is not limited to ultrasonic welding, and can be appropriately applied as long as both are firmly joined. For example, a liquid or gel (glue) adhesive may be applied, filled, and cured to bond them together. Further, the resin case 7 is not limited to the form constituted by the resin base 71 and the cover member 72 and the like, but may be any form as long as the movable piece 4 is sandwiched and held by two or more parts. In this case, one is the first case and the other is the second case.

  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 heat transfer part is formed in the integrated movable piece, the structure of the breaker is simplified, and further miniaturization can be achieved. Further, in the present embodiment, the self-holding circuit by the PTC thermistor 6 is provided, but the present invention can be applied even in a form in which such a configuration is omitted.

  Further, as shown in JP-A-2005-203277, the movable piece 4 is structurally separated into the terminal 41 side and the movable contact 3 side in the contact portion 42 or the vicinity thereof. The invention may be applied. In this case, the resin coating 42d may be formed on one or both of the rear surface of the arm terminal and the front surface of the movable arm. Further, the arm terminal and the movable arm may be fixed by welding or the like.

  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. 9 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. 10 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 1,1A Breaker 2 Fixed piece 3 Movable contact 4, 4A Movable piece 5 Thermally responsive element 7 Resin case 8 Cover piece 21 Fixed contact 41 Terminal 42 Contact part 42d Resin coating 43 Elastic part 101 Secondary battery 102 Safety circuit

Claims (7)

A fixed piece having a fixed contact, a movable piece having a movable contact, the movable piece pressing the movable contact against the fixed contact, and the movable contact moving away from the fixed contact by being deformed as the temperature changes. In a breaker comprising a thermally responsive element that operates the movable piece as described above, and a resin case that houses the fixed piece, the movable piece and the thermally responsive element,
The movable piece includes a terminal protruding outside the resin case, an elastic part that generates an elastic force for pressing the movable contact against the fixed contact, and the resin between the terminal and the elastic part. A contact portion that contacts the case;
A breaker characterized in that a resin film is formed on the contact portion.   The breaker according to claim 1, wherein the resin film is formed on a surface facing the thermally responsive element.   The breaker according to claim 1, wherein the resin coating is formed on a surface opposite to a surface facing the thermoresponsive element.   The resin film is formed, at least in part, continuously from one end to the other end of the contact portion in a direction perpendicular to a direction in which the elastic portion extends. The breaker as described in any one of Claims 1 thru | or 3.   The breaker according to any one of claims 1 to 4, wherein the resin film is formed so as to avoid a contact portion with the thermally responsive element.   A safety circuit for an electric device comprising the breaker according to any one of claims 1 to 5.   A secondary battery circuit comprising the breaker according to any one of claims 1 to 5.

Images