JP2013171642A - Breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress spark discharge between contacts by eliminating insufficient contact gap that occurs when a breaker is made compact and increasing the speed of a breaking operation.SOLUTION: A breaker includes first and second conductors 1 and 2 each having a terminal exposed to the outside and first and second conduct parts 12 and 22 that contact a PTC thermistor 5, a movable arm 3 for electrically connecting the first and second conductors 1 and 2, and a thermally-actuated element 4 which interrupts the breaker by inversion above the first contact part 12. The first contact part 12 has a protrusion which comes into contact with the top face 5a of the PTC thermistor 5, bulges toward the thermally-actuated element 4, and comes into contact with the thermally-actuated element 4 while the breaker is interrupted.

Description

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

  The power source of portable devices such as smartphones, notebook computers, and tablet computers is mainly secondary batteries such as lithium ion batteries. A safety device that is indispensable for a lithium ion battery is equipped with a thermal circuit breaker that senses a high temperature state, assuming that the safety circuit does not operate. Among such thermal breakers, the breaker is advantageous in that the operating temperature is set accurately and can be used repeatedly.

  In recent years, portable devices such as those described above have become thinner, and lithium ion battery packs are also desired to be thinner and smaller, and the breaker size has been reduced. However, the miniaturization is accompanied by a reduction in the contact gap. In reducing the contact gap, spark discharge (spark) frequently occurs between the contacts, and the life of the breaker may be shortened due to damage to the contacts. As a technique for overcoming such a problem, a noble base is integrally formed in a state where a positive characteristic (PTC) thermistor is sandwiched between a first fixed terminal and a second fixed terminal, and the positive characteristic thermistor is held. Thus, there has been proposed a switch device that can easily connect the first fixed terminal and the second fixed terminal to the positive temperature coefficient thermistor. With this conventional technology, the switch device (breaker) can be reduced in size and productivity can be improved, and the connection between the fixed terminal and the positive temperature coefficient thermistor is facilitated, so that the breaker can be used when shifting from normal to abnormal conditions. The time required for switching circuits inside is shortened, and the occurrence of sparks can be suppressed.

JP 2005-142147 A

  However, in the above-described prior art, since the first fixed terminal and the second fixed terminal are always connected to the positive temperature coefficient thermistor, the switching of the current from the normal circuit to the abnormal circuit is accelerated. The contact gap is not particularly increased. For this reason, even if the time zone in which the spark is concerned is shortened by switching the current as described above, the above-mentioned problem is not eliminated when the size of the contact gap is insufficient.

  An object of the present invention is to provide a design that accelerates switching of a circuit inside a breaker and sufficiently enlarges a contact gap in a downsized breaker.

  In order to achieve the above object, the breaker of the present invention is in contact with the housing, the plate-like PTC thermistor, the first terminal portion and the second terminal portion exposed to the outside of the housing, and the PTC thermistor. A first conductor and a second conductor each having a first contact portion and a second contact portion, a fixed contact provided on at least one of the first conductor or the second conductor, and a contact or separation with the fixed contact. A movable arm that electrically connects the first conductor and the second conductor, and a curved shape that is disposed above the first contact portion and is reversed by a snap action. The first contact portion is in contact with the upper surface of the PTC thermistor, and further protrudes toward the thermal response element, and the movable contact is fixed by reversing the thermal response element. State away from contact Has a projection in contact with Oite curved shape, the second contact portion, characterized in that the contact with the lower surface of the PTC thermistor.

  In the breaker of the present invention, the fixed contact is provided on one of the first conductor and the second conductor, and the movable arm is inserted with the PTC thermistor and the first conductor or the second conductor is on the opposite side of the fixed contact. It is characterized in that it is fixed in connection with the other one of the two conductors.

  In the breaker of the present invention, two fixed contacts are provided on a part of the first conductor and the part of the second conductor which are parallel to each other, and the movable arm is on the side opposite to the fixed contact by inserting the PTC thermistor. The two fixed contacts are electrically connected to each other via a movable arm in a state of being in contact with the movable contact.

  Further, in the breaker of the present invention, the movable arm is structurally separated from the first conductor and the second conductor, and the movable contacts are arranged by inserting PTC thermistors and provided at both ends of the movable arm, respectively. The contacts are arranged by inserting a PTC thermistor and provided on the first conductor and the second conductor, respectively.

  The breaker according to the present invention accelerates the operation of separating the contacts and switching of the circuit inside the breaker, thereby greatly expanding the contact gap. Therefore, it is possible to reduce spark discharge (spark) generated between the contacts that are separated when the breaker reaches a cutoff state due to a load such as overcurrent or overcharge.

  Further, the contact point between the fixed contact and the movable contact is provided at one end, and the breaker can be downsized by inserting the PTC thermistor and fixing the movable arm on the opposite side of the fixed contact.

FIG. 1 is an assembled view and a cross-sectional view showing the first embodiment. FIG. 2 is a cross-sectional view showing the second embodiment. FIG. 3 is a perspective view showing the third embodiment. FIG. 4 is a cross-sectional view showing the fourth embodiment. FIG. 5 is a cross-sectional view showing a modification of the protrusion 1A. FIG. 6 is a plan view showing a modification of the contact portion 12.

  Embodiments of a breaker according to the present invention will be described below with reference to the drawings. 1A and 1B are an assembled view and a cross-sectional view showing Embodiment 1 of the present invention. FIG. 1 (a) shows an assembly diagram, and FIGS. 1 (b) and 1 (c) show cross-sectional views in normal and abnormal conditions, respectively. The breaker 100 according to the first embodiment includes a first conductor, a second conductor (hereinafter referred to as a conductor 1 and a conductor 2 respectively), a movable arm (hereinafter referred to as an arm 3), a thermal actuator (hereinafter referred to as a disk 4), and a positive characteristic circuit. A mr (hereinafter referred to as PTC5) is housed in a casing (hereinafter referred to as case 6). The case 6 includes a base 61 and a cover 62. The shapes, dimensions, materials, etc. of these members can be applied to those in conventional breakers unless otherwise specified.

  The conducting wire 1 has a terminal portion 11 exposed to the outside of the case 6 and a first contact portion (hereinafter referred to as a contact portion 12) that contacts the upper surface 5a of the PTC 5 inside the case 6. The conducting wire 1 is formed by pressing a metal plate mainly composed of copper. Further, a protrusion 1A is formed on the contact portion 12 in the upward direction. A part between the terminal portion 11 and the contact portion 12 of the conducting wire 1 is embedded in the resin of the base 61. Further, one end of the arm 3 is fixed to the arm fixing portion f exposed inside the case 6 between the terminal portion 11 and the contact portion 12 of the conducting wire 1.

  The conducting wire 2 is formed by pressing a metal plate containing copper as a main component, like the conducting wire 1. The conducting wire 2 has a terminal portion 21 exposed to the outside of the case 6 and a second contact portion (hereinafter referred to as a contact portion 22) that contacts the lower surface 5b of the PTC 5 inside the case 6. Furthermore, the conducting wire 2 has a fixed contact c <b> 1 formed by coating, plating, cladding, or the like with a good conductor mainly composed of silver or the like between the contact portion 22 and the terminal portion 21. The fixed contact c1 is exposed to the internal space of the case 6 and appropriately contacts or separates from the movable contact c2.

  The arm 3 is formed by pressing a metal plate containing copper as a main component, like the conducting wire 1 and the conducting wire 2. At the tip of the arm 3, there is a movable contact c2 formed of a good conductor mainly composed of silver or the like. The other end of the arm 3 is fixed by an arm fixing portion f of the conducting wire 1 and is structurally and electrically connected to the conducting wire 1 by welding or the like. An intermediate portion of the arm 3 is a movable portion 31, which is disposed above the disk 4 and the PTC 5 so as to cover and straddle the disk 4, and is subjected to deformation of the disk 4 due to thermal change, so that the fixed contact c1 and the movable contact Contact or separate c2. The arm 3 has a general shape that is curved or bent by pressing in the movable portion 31. When the fixed contact c <b> 1 and the movable contact c <b> 2 are in contact, the conducting wire 1 and the conducting wire 2 are electrically connected via the arm 3. At this time, the electrical resistance is extremely low and negligible.

  The disk 4 is disposed so as to cover the contact portion 11 in the upward direction of the PTC 5. The disk 4 has an initial shape curved in an arc shape and is made of a composite material such as bimetal or trimetal. A curved shape is formed on the disk 4. This curved curved surface is reversed by a snap action when abnormal. Inversion is a mirroring operation that changes the shape of the curve from an upwardly convex curved surface to a downwardly convex shape while maintaining the positional relationship of the front and back surfaces of the disk 4 with the arm 3 facing upward. By this reversal operation, the movable portion 31 is pushed upward, and the movable contact c2 and the fixed contact c1 are separated. The shape of the disk 4 is restored when it is normal, and the movable contact c1 and the fixed contact c2 come into contact again. The shape of the disk 4 can be formed by pressing. The material and shape of the disk 4 are not particularly limited as long as the above-described inversion and return contact or separation are performed at a predetermined temperature, but a rectangle is preferable from the viewpoint of productivity and efficiency of the inversion operation.

  PTC5 is a disk-shaped or square-shaped positive thermistor. Two electrodes are provided on the upper surface 5a and the lower surface 5b of the PTC 5 by applying, plating, vapor-depositing or the like a good conductor mainly composed of silver or the like. Several small protrusions b provided on the conductive wire 1 and the conductive wire 2 are in contact with these electrodes, and the PTC 5 is sandwiched vertically and held in the case 6. At the time of abnormality, the minute leakage current L passes through the PTC 5 through these electrodes, so that the PTC 5 generates heat. The state where the disk 4 is reversed by the radiant heat is maintained.

  The contact portion 12 is formed with a protrusion 1 </ b> A that protrudes toward the disk 4. When the arm 3 is lifted by the reversal of the disk 4 due to a high temperature and the movable contact c1 is separated from the fixed contact c2, the protrusion 1A and the inverted curved shape of the disk 4 come into contact with each other. On the other hand, in a normal state, the projection 1A is entirely or mostly accommodated in a space defined by the upper surface 5a of the PTC 5 and the curved shape of the disk 4. The protrusion 1A of the present embodiment is provided at or near the center of the upper surface 5a of the PTC 5 at the center, but is not particularly limited as long as it is on the upper surface 5a of the PTC 5 and does not hinder the housing of the disk 4 in the case 6. It is not something. The protrusion 1A can be simultaneously applied by press working when the conductive wire 1 is formed.

  The base 61 is a molded product in which metal pieces such as the conductive wire 1 and the conductive wire 2 are embedded in resin by insert molding. The resin portion of the base 61 forms a peripheral wall having an opening in the upward direction with the conductive wire 2 as a bottom surface. From this opening, the disk 4 and the arm 3 are introduced and housed inside the case. The stored edges of the arm 3 and the disk 4 are guided by the frame formed inside the peripheral wall during the reversing operation.

  A cover plate 6a is embedded in the cover 62 by insert molding. The cover plate 6a is formed by pressing the above-described metal plate mainly composed of copper or a metal plate such as stainless steel. The cover plate 6a comes into contact with the upper surface of the arm 3 through some small cover protrusions 6b as needed during normal times or in an abnormal state, and restricts the movement of the arm 3 and also improves the rigidity and strength of the cover 62 and thus the case 6. Increase. The resin portion of the cover 62 is joined to the peripheral wall of the base 61 and seals the inside of the case 6.

  The base 61 and the cover 62 constituting the case 6 are molded from a resin such as flame retardant polyamide, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT) having excellent heat resistance. Conductor 1, conductor 2, and PTC 5 are embedded in base 61, and PTC 5 is held between upper surface 5a and lower surface 5b by contact portion 12 of conductor 1 and contact portion 22 of conductor 2, respectively. Thus, insert molding is performed in a state where the conducting wire 1, the conducting wire 2 and the PTC 5 are held, and a completed base 61 can be obtained by providing a resin portion.

  The disk 4 is introduced into the completed base 61 and placed on the PTC 5 and the contact portion 12. Subsequently, the arm 3 is introduced, and the movable portion 31 is disposed on the disk 4. The introduced arm 3 is joined and fixed to the conductor 1 by welding at the arm fixing portion f. Finally, the cover 62 is placed on the base 61 into which each member has been introduced to close the opening, and then the base 61 and the cover 62 are joined at the resin portion by ultrasonic welding to complete the breaker 100 (FIG. 1 (a)).

  The breaker 100 is connected in series at a terminal 11 and a terminal 21 to a circuit on a battery pack such as a lithium ion battery. When the temperature around the breaker 100 rises at the time of abnormality or the arm 3 generates heat due to overcurrent, the disk 4 is reversed, the movable part 31 is pushed up, and the fixed contact c1 and the movable contact c2 are separated. At this time, a leakage current is generated between the conducting wire 1 and the conducting wire 2 directly through the PTC 5, and a self-holding circuit is formed by the heat generated by the PTC 5 (FIGS. 1B and 1C).

  FIG. 2 is a cross-sectional view showing a second embodiment of the present invention. In the second embodiment, the arm 3 is fixed to the arm fixing portion f of the conducting wire 2 and is structurally connected to the conducting wire 2. The arm fixing portion f is provided in a portion of the base 62 between the terminal 21 and the contact portion 22 that is exposed to the space inside the case 6 of the conducting wire 2. The fixed contact c1 is provided between the terminal 11 and the contact portion 12 of the conducting wire 1. Even with such an arrangement, the arm 3 can function the breaker 100 as in the first embodiment. The structure of each member is the same except that the positions of the fixed end and the open end of the arm 3 are different.

  FIG. 3 is a perspective view showing Embodiment 3 of the present invention. In the third embodiment, the fixed contact c1 and the fixed contact c3 are provided in places where the conducting wire 1 and the conducting wire 2 are parallel to each other. In the present embodiment, one of the conducting wire 1 and the conducting wire 2 extends beyond the PTC 5 and forms a portion parallel to the other conducting wire. In FIG. 3, the lead wire 1 is over the PTC 5 at the contact portion 12. The arm 3 has a fixed contact c1 and a movable contact c2 in contact with the fixed contact c3 at one end, and is fixed at another end. In the drawing, a form in which the fixed end of the arm 3 is structurally connected to the conductor 1 is shown, but a form in which the arm 3 is connected to the conductor 2 is also possible. The structure and manufacturing method of each member are the same except that the position and number of the contacts are different.

  FIG. 4 is a cross-sectional view showing a fourth embodiment of the present invention. The arm 3 of the fourth embodiment does not have a fixed end that is continuously restrained by joining, fitting, engagement, or the like. The arm 3 is held between the cover 62 and the PTC 5 at the center of the case 6. Furthermore, the movable part 31 of the arm 3 is formed integrally with the thermally responsive element. In the fourth embodiment, the fixed contact c1 and the fixed contact c3 are provided on both the conductive wire 1 and the conductive wire 2 with the PTC 5 interposed therebetween. The movable contact c2 and the movable contact c4 are provided at corresponding locations on both ends of the arm 3. The arm 3 is pressed downward at the center of the cover 62 by a pressing portion 6 b provided on the cover 62. In the illustrated form, the arm 3 is integrated with the thermally responsive element. At each contact, contact or separation is performed by a flapping-like operation performed by the arm 3. The structure and manufacturing method of each member are the same except that the position and number of the contacts are different.

  The shape of the protrusion 1A is not limited to that in the above-described embodiment, and the protrusion 1A exists as a single dot on the upper surface 5a of the PTC 5, and may be singular, plural, or linear. Good. The arrangement of the protrusions 1A is not particularly limited as long as the protrusions 1A come into contact with the disk 4 that is inverted when there is an abnormality on the upper surface 5a of the PTC 5. The protrusion 1A may be closer to the contact point from the viewpoint of reducing the height of the breaker 100 and increasing the contact gap.

  For example, as shown in FIG. 5, the protrusion 1A has a semicircular cross section, a bent shape as shown in FIG. 5A, and a stepped shape as shown in FIG. 5A. A rounded one (curl bending) as shown in FIG. 5C, a folded one (hemming bending) as shown in FIG. Of the plurality of shapes described above, some may be appropriately combined, or the same type may be applied a plurality of times. Further, as shown in FIG. 5E, another material 1b may be formed by adding the protrusion 1A to the upper surface 5a by welding, cladding, caulking, or the like. For such a welding material, it is preferable to use a material having a relatively high resistance value from the viewpoint of improving the withstand voltage. The welding material may penetrate through the contact portion 12 and reach and contact the upper surface 5a of the PTC 5.

  The self-holding of the breaker 100 is performed by the heat generated by the PTC 5 being transmitted to the disk 4 and the disk 4 continuing to push up the movable portion 31. Therefore, it is desirable to suppress heat transfer from the PTC 5 to the contact portion 12 and heat dissipation at the terminal portion 11. A structure in which the radiant heat of the PTC 5 is easily transmitted to the disk 4 and the heat transfer from the contact portion 12 to the terminal portion 11 is suppressed is desired. Therefore, from the viewpoint of the self-holding circuit, the contact portion 12 is provided with a hole a1 (FIG. 6A), a notch a2 (FIG. 6B), and the like in a region overlapping the upper surface 5 of the PTC 5 in plan view. Is preferred. The bridging portion 14 that connects the contact portion 12 and the exposed portion 13 of the conducting wire 1 through a hole or notch can be formed by pressing, as with other portions of the conducting wire 1. Further, a width larger than the diameter of the PTC 5 may be provided in the short direction of the lead wire 1, and the shape of the contact portion 12 may be elongated in the short direction of the lead wire 1 so as to straddle the upper surface 5 (FIG. 6C). . Further, the contact portion 12 of FIG. 6C is further provided with a step so as to sandwich the PTC 5 between the contact portion 12 and the bridging portion 14, and the contact portion 12 holds the PTC 5 more stably.

  In the conventional product, there is a time lag when switching from the circuit via the arm 3 (normal time) to the circuit via the PTC 5 (during abnormality), and there is a risk of sparking between the contacts and causing contact wear. In the present invention, the contact portion 12 and the contact portion 22 are in contact with the PTC 5 on the upper surface 5a and the lower surface 5b, respectively, so that a circuit is always formed via the PTC 5, and immediately when the disk 4 is reversed in the event of an abnormality. The circuit switches. As a result, harmful sparks are less likely to occur.

  Further, while the disk 4 is reversed, the protrusion 1A pushes the disk 4 further upward from the upper surface 5a of the PTC 5, so that the contact gap is expanded. In addition, since the disc 4 comes into contact with the protrusion 1A earlier than the disc 4 comes into contact with the upper surface 5a of the conventional PTC 5, the breaking operation of the breaker 100 becomes even quicker. Similar speeding-up is also possible by providing the arm 3 with a small arm protrusion 3b that protrudes and contacts the disk 4.

  Further, since the PTC 5 is protected by the molding resin, the breakage of the PTC 5 can be reduced when the breaker 100 is processed and used. Since the number of parts is reduced when the breaker 100 is assembled, the number of processes is reduced. The curved internal space protruding above the disk 4 is closed by the projection, so that the space efficiency is improved, which is advantageous for downsizing and low profile. Since the PTC 5 is firmly fixed by the conducting wire 1 and the molding resin, the contact pressure between the contacts is stabilized against vibration without the PTC 5 being shaken inside the case 6.

  In addition, in the form in which the conducting wire 1 and the conducting wire 2 are spatially arranged in series and the terminal portions are arranged at both ends as in the first and second embodiments, it is structurally compatible to reduce the size and increase the current capacity. Easy. In a form like Example 3, it becomes easy to concentrate a terminal on the one end of the breaker 100. FIG. In the embodiment in which the contacts are provided at both ends of the arm 3 as in the fourth embodiment, it is easy to increase the electric resistance when an abnormality occurs.

  The arm 3 and the disk 4 may be formed integrally by forming the arm 3 from bimetal or trimetal. In this case, the configuration of the breaker is simplified and further downsizing can be achieved. Moreover, the arm 3 and the conducting wire 1 or the conducting wire 2 can be integrally formed. In this case, if a part of the arm 3 or the conducting wire 1 is used for the contact portion 12, the number of parts is reduced. Further, the shape of the contact portion 12 and / or the contact portion 22 may be such that the PTC 5 is held by the step bend a3 formed along the upper surface 5a or the lower surface 5b and the side surface of the PTC 5, and thereby the PTC 5 at the time of processing. The stationary state is further stabilized.

100 breakers,
1 conductor (first conductor),
12 contact portion (first contact portion),
1A protrusion,
2 conductor (second conductor),
22 contact portion (second contact portion),
3 Arm (movable arm) 4 Disc (thermally responsive element),
5 PTC (PTC thermistor),
5a top surface,
5b bottom surface,
6 Case (housing),
61 base,
62 cover,

Claims (5)

A housing,
A plate-like PTC thermistor;
A first conductor and a second conductor each having a first contact part and a second terminal part exposed to the outside of the housing, and a first contact part and a second contact part contacting the PTC thermistor;
A fixed contact provided on at least one of the first conductor or the second conductor;
A movable arm having a movable contact that contacts or separates from the fixed contact, and electrically connects the first conductor and the second conductor;
A thermal response element disposed above the first contact portion, provided with a curved shape that is reversed by a snap action, and contacting or separating the fixed contact and the movable contact;
The first contact portion is in contact with the upper surface of the PTC thermistor, is raised toward the thermal responsive element, and the movable contact is separated from the fixed contact by reversing the thermal responsive element. With protrusions that come into contact with
The breaker characterized in that the second contact portion is in contact with the lower surface of the PTC thermistor.   2. The breaker according to claim 1, wherein the first conductor and the second conductor are embedded in the casing that accommodates the PTC thermistor, the movable arm, and the thermally responsive element. The fixed contact is provided on one of the first conductor or the second conductor,
The movable arm is fixed by being structurally connected to the other one of the first conductor or the second conductor on the side opposite to the fixed contact by inserting the PTC thermistor. 1 or 2 breakers. Two fixed contacts are provided on a part of the first conductor and a part of the second conductor,
The movable arm is fixed on the opposite side of the fixed contact by inserting the PTC thermistor,
3. The breaker according to claim 1, wherein the two fixed contacts are electrically connected to each other through the movable arm in a state of being in contact with the movable contact. The movable arm is structurally separated from the first conductor and the second conductor,
The movable contacts are arranged by inserting the PTC thermistor and are provided at both ends of the movable arm,
The breaker according to claim 1 or 2, wherein the fixed contact is disposed with the PTC thermistor inserted thereinto and provided on the first conductor and the second conductor, respectively.

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