JP2012133947A - External ptc element unit and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external PTC element unit which can be attached reliably to the terminal protrusion of a terminal in a battery.SOLUTION: The external PTC element unit 20 comprises a cap-like support 21, a PTC element 22 and a terminal strip 23 for external connection. The cap-like support 21 consists of a top plate 26 and a sidewall 27, and is formed using a conductive material. The PTC element 22 has the element rear surface 34 side bonded and fixed onto the first main surface 24 of the top plate 26. The terminal strip 23 for external connection is bonded and fixed onto the element surface 33 of the PTC element 22 so as to cover the PTC element 22. In a state where the second main surface 25 side of the top plate 26 of the cap-like support 21 is arranged to face the upper end face of a terminal protrusion 12, the sidewall 27 of the external PTC element unit 20 is connected to the side surface of the terminal protrusion 12.

Description

  The present invention relates to an external PTC element unit having a current protection function and a battery to which the external PTC unit is attached.

  Conventionally, an assembled battery is mounted as a power source for portable electric devices such as cameras and lights. In this type of battery pack, a plurality of batteries are connected in series to flow a large current, and a PTC (Positive Temperature Coefficient) element is used as a protective element (Patent Documents 1 and 2). Etc.). This PTC element usually has a low resistance, but its electrical resistance increases when a large current flows through the battery and the battery temperature rises. Therefore, if this PTC element is used, even if a circuit element or the like is short-circuited and a large current flows at the time of failure of the electric device, the battery current can be cut off.

  In Patent Document 1, a PTC element is mounted on a flat terminal side or a convex terminal side of a battery. Moreover, in patent document 2, the PTC element is mounted | worn with the convex terminal side in a battery.

  By the way, a flat terminal in a battery has a relatively large area, and when a PTC element or a lead plate is attached to the entire surface of the terminal, the planar size of the PTC element or the lead plate is increased, resulting in increased component costs. When the planar size of the PTC element or the lead plate is reduced and the PTC element is attached to a part of the flat terminal, the distance between the flat surface of the terminal and the lead plate (distance corresponding to the thickness of the PTC element) becomes short. . For this reason, there is a possibility that the mating terminal connected to the battery comes off the position of the lead plate and contacts the flat surface of the battery terminal. In this case, the PTC element is short-circuited, and overcurrent cannot be prevented. In order to avoid this, it is necessary to insulate the flat surface of the battery terminal. However, in addition to the time and effort, the cost of the components increases. Therefore, in order to reduce the component cost, it is preferable to mount the PTC element on the convex terminal side having a relatively small area.

JP 2000-340192 A Japanese Utility Model Publication No. 1-81870

  In Patent Document 1, when a PTC element is mounted on the upper surface of a battery-shaped convex terminal (terminal protruding portion), a disk-shaped metal plate having a size substantially equal to the upper surface of the terminal is used, and the periphery of the metal plate is placed on the upper surface of the terminal. The PTC element is laminated on the metal plate by welding and fixing. In this case, since it is necessary to secure a welding location in the metal plate, a space for providing the PTC element is reduced, and it may be impossible to install a PTC element having sufficient performance for preventing overcurrent. Moreover, if the installation space of a PTC element is ensured and a welding part is decreased, joining strength will become insufficient. If a force is applied to the PTC element in the lateral direction, there is a concern that the PTC element may be detached from the terminal upper surface. Incidentally, the battery of Patent Document 2 also has the same problem because the PTC element is welded and fixed to the upper surface of the convex terminal of the battery.

  Further, Patent Document 1 also proposes a battery in which a PTC element is installed at a base portion of a convex terminal (a terminal flat portion provided around a terminal protruding portion). For example, some lithium batteries have different polarities between the convex terminal and the base of the terminal that is one step lower than that. In this battery, if a PTC element is provided at the base of the convex terminal, a short circuit between the electrodes becomes a problem. Therefore, a configuration such as providing an insulator between metal members to avoid the short circuit becomes complicated, and it is difficult to realize the configuration.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an external PTC element unit that can be securely attached to a terminal protrusion of a terminal in a battery. Another object of the present invention is to provide a battery in which an external PTC element unit can be attached to the terminal protruding portion of a terminal and overcurrent can be reliably prevented.

  Means [1] to [7] for solving the above problems are listed below.

  [1] An external PTC element unit that can be attached to a battery having a terminal protrusion at the center of the terminal, and has a first main surface and a second main surface and is equivalent to the terminal protrusion in plan view A cap-like support formed of a conductive material, comprising a top plate having dimensions and a shape, and a side wall portion projecting vertically from the outer peripheral portion of the second main surface of the top plate; A PTC element having a back surface and an element surface, the element back side being bonded and fixed on the first main surface of the top plate, and an external bonded and fixed on the element surface to cover the PTC element A terminal plate for connection, wherein the side wall portion is connectable to a side surface of the terminal protruding portion in a state in which the second main surface side of the top plate is disposed opposite to the upper end surface of the terminal protruding portion. A featured external PTC element unit.

  According to the invention described in the means 1, the PTC element unit can be provided at the upper end of the terminal projecting portion of the battery terminal. Further, in the battery, the upper end surface of the terminal projecting portion has a relatively small area, and the PTC element unit can be downsized as compared with the case where it is provided on a flat terminal. Furthermore, since the side wall portion of the cap-like support is fixed to the side surface of the terminal protruding portion, even if a lateral load is applied to the PTC element unit, the problem that the fixing position of the PTC element unit is shifted is avoided. can do.

  [2] The external PTC element unit according to [1], wherein the PTC element has a disk shape having a through hole in a central portion.

  According to the invention described in Means 2, since the PTC element is formed in a disk shape and has a through hole at the center thereof, the weight of the element can be reduced.

  [3] In the means 2, a conductive member is laminated on the surface of the external connection terminal plate in a state in which a part of the external connection terminal plate projects from the external connection terminal plate. An external PTC element unit, which is fixed by welding to the center portion of the external connection terminal plate.

  When the conductive member is fixed by welding to the central portion of the external connection terminal plate as in the invention described in the means 3, heat is applied to the central portion of the external connection terminal plate. In this case, since the PTC element is formed in a disk shape and has a through hole in the center thereof, the PTC element can be disposed avoiding the central part where heat is easily applied, and the performance of the PTC element is deteriorated due to thermal stress. Can be prevented.

  [4] The external PTC element unit according to any one of means 1 to 3, wherein the side wall portion of the cap-shaped support is divided into a plurality of pieces with a notch portion therebetween.

  According to the invention described in the means 4, since the side wall portion of the cap-shaped support is divided into a plurality of pieces with the notch portion therebetween, the side wall portion is easily bent toward the terminal protruding portion side. Can be reliably contacted.

  [5] In the means 4, a plurality of projection welding projections are formed on the inner surface of the side wall portion divided into a plurality of pieces so as to face each other across the center of the cap-shaped support. External PTC element unit.

  According to the invention described in the means 5, since the projection welding projection is provided on the inner surface of the side wall portion divided into a plurality of pieces, the side wall portion can be reliably welded to the side surface of the terminal protruding portion. Further, during projection welding, one electrode of the pair of electrodes is brought into contact with the side wall portion of the cap-shaped support, and the other electrode is brought into contact with the side surface of the terminal protruding portion exposed at the position of the notch portion. And resistance welding can be performed reliably. Furthermore, when the side wall portion of the cap-shaped support is welded, heat is not easily transmitted to the PTC element provided on the top plate of the cap-shaped support, so that the performance deterioration of the PTC element due to thermal stress can be prevented. Moreover, when welding the top plate of a cap-shaped support body, since it is necessary to install a PTC element avoiding a welding location in the top plate, the installation space of a PTC element decreases. In contrast, in the present invention, the side wall portion of the cap-shaped support is welded, and the top plate has the same dimensions as the terminal protruding portion, so that a sufficient installation space for the PTC element can be secured.

  [6] In any one of means 1 to 5, a recess is formed in the first main surface of the top plate of the cap-shaped support, and the PTC element is disposed and soldered in the recess. An external PTC element unit.

  According to the invention described in the means 6, since the concave portion is formed on the first main surface of the top plate of the cap-shaped support, the PTC element can be reliably arranged at the position of the concave portion, and the PTC element and the cap It can be easily connected to the shaped support by soldering. Furthermore, according to this configuration, even if a weight is applied to the PTC element unit in the lateral direction, the problem that the PTC element falls off from the cap-shaped support can be avoided.

  [7] A battery to which the external PTC element unit according to any one of means 1 to 6 is attached.

  According to the invention described in the means 7, overcurrent of the battery can be surely prevented by the external PTC element attached to the terminal protrusion in the battery.

  As described above in detail, according to the inventions described in the means 1 to 6, it is possible to provide an external PTC element unit that can be securely attached to the terminal protruding portion of the terminal in the battery. Further, according to the invention described in the means 7, it is possible to provide a battery in which an external PTC element unit can be attached to the terminal protruding portion of the terminal, and overcurrent can be reliably prevented.

The perspective view which shows the lithium battery of one Embodiment. The disassembled perspective view which shows the structure of the PTC element unit of one Embodiment. Sectional drawing which shows the structure of the PTC element unit of one Embodiment. The perspective view which shows the lithium battery of one Embodiment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a lithium battery 10 according to the present embodiment. 2 is an exploded perspective view showing the PTC element unit 20 attached to the lithium battery 10, and FIG. 3 is a cross-sectional view showing the PTC element unit 20.

  As shown in FIG. 1, the lithium battery 10 is a cylindrical battery, and has a terminal protrusion 12 at the center of a terminal 11 provided on one end face (upper end face in FIG. 1). In this lithium battery 10, an external PTC element unit 20 is attached to the terminal protrusion 12 of the terminal 11.

  As shown in FIGS. 2 and 3, the external PTC element unit 20 of the present embodiment includes a cap-shaped support body 21, a PTC element 22, and an external connection terminal plate 23.

  The cap-shaped support 21 is a member for supporting the PTC element 22 and has a first main surface 24 and a second main surface 25 and has the same size and shape as the terminal protrusion 12 in plan view. The top plate 26 and a side wall portion 27 projecting vertically from the outer peripheral portion of the second main surface 25 of the top plate 26. The cap-shaped support body 21 is formed in a cap shape using a conductive material such as a nickel-plated steel plate. In the present embodiment, the terminal protrusion 12 of the terminal 11 has a circular shape, and the top plate 26 of the cap-shaped support 21 is also formed in a circular shape. A recess 28 for arranging the PTC element 22 is formed on the first main surface 24 of the top plate 26. Here, when the depth of the recess 28 is d and the thickness of the PTC element 22 is T, the recess 28 is formed so that the relationship of 0 <d <T / 2 is satisfied.

  Further, the side wall 27 of the cap-shaped support 21 is divided into a plurality of pieces with a notch 29 therebetween. A plurality of projection welding projections 30 are formed on the inner surface of the side wall portion 27 divided into a plurality of pieces so as to face each other with the center of the cap-shaped support 21 interposed therebetween. The projection welding projection 30 is a so-called dowel projection whose cross section is formed in an R shape. Here, when the distance between the opposing side wall portions 27 is CS and the radius of the terminal protruding portion 12 is r, the side wall portions 27 are formed so that CS ≧ 2r. Further, when the distance between two opposing protrusions 30 is DB, the protrusions 30 of the side wall portion 27 are formed so that the relation DB <2r is established. That is, the distance DB between the protrusions 30 is narrower than the diameter (= 2r) of the terminal protrusion 12. If it does in this way, when the side wall part 27 of the cap-shaped support body 21 is engage | inserted in the terminal protrusion part 12 of the terminal 11, each protrusion 30 will contact the side surface of the terminal protrusion part 12 reliably.

  Furthermore, in order to make it easier to fit the cap-shaped support 21 into the terminal protruding portion 12 of the terminal 11, an R-shaped lead-in portion 31 formed so as to spread outward is provided at the tip of the side wall portion 27. When the distance between the tips of the R-shaped guiding part 31 is A, the guiding part 31 is formed so that 2r <A. Further, as shown in FIG. 1, the height of the side wall portion 27 is lower than the height of the terminal protruding portion 12 to be attached, and the side wall portion 27 of the cap-shaped support body 21 is formed of the terminal protruding portion 12. The surrounding terminal flat portion 13 is not covered. In the present embodiment, the height of the side wall portion 27 is about half of the height of the terminal protruding portion 12.

  As shown in FIGS. 2 and 3, the PTC element 22 has a disk shape having an element surface 33 and an element back surface 34, and a through hole 35 is formed at the center thereof. The PTC element 22 has a structure in which a conductive polymer material having positive temperature characteristics is sandwiched between element electrodes (specifically, plate-like nickel electrodes), and the resistance value increases as the temperature rises. To do. The element back surface 34 side of the PTC element 22 configured as described above is bonded and fixed onto the first main surface 24 of the top plate 26. Specifically, the PTC element 22 is disposed in the recess 28 formed in the top plate 26, and the PTC element 22 is soldered to the position of the recess 28 of the top plate 26 by solder reflow. Since the recess 28 is formed shallower than half the thickness (T / 2) of the PTC element 22, when the PTC element 22 is soldered to the recess 28, the element surface 33 side of the PTC element 22 is the recess 28. It is in a state protruding from.

  The external connection terminal plate 23 is bonded onto the element surface 33 so as to cover the PTC element 22. The external connection terminal plate 23 is formed in a disk shape using a conductive material such as a nickel-plated steel plate, and is soldered onto the element surface 33 of the PTC element 22 by solder reflow.

  The PTC element unit 20 configured as described above is connected to the terminal protrusion 12 of the terminal 11 by resistance welding. Specifically, the side wall 27 of the cap-like support 21 is fitted into the terminal protrusion 12 of the terminal 11 in the lithium battery 10, and the second main surface 25 side of the top plate 26 is opposed to the upper end surface of the terminal protrusion 12. Arrange. Here, one electrode of the pair of electrodes for performing resistance welding is brought into contact with the side wall portion 27 of the cap-shaped support 21, and the other electrode (abandoned electrode) is positioned at the notch portion 29 of the side wall portion 27. Is brought into contact with the side surface of the terminal protruding portion 12 exposed. In this state, the side wall 27 of the cap-like support 21 is welded to the side surface of the terminal protruding portion 12 by applying pressure while simultaneously applying current to the projection 30 to heat the portion 30 and heating.

  Furthermore, in the PTC element unit 20 of the present embodiment, a metal lead plate 37 (conductive member) for external connection is connected to the surface of the external connection terminal plate 23 (see FIG. 4). In the present embodiment, the lead plate 37 is laminated and disposed with a part of the lead plate 37 protruding from the external connection terminal plate 23, and is fixed by welding to the center portion of the external connection terminal plate 23.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) In the lithium battery 10 of the present embodiment, the PTC element unit 20 is provided on the upper end of the terminal protrusion 12 having a relatively small area. In this case, since the size of the PTC element unit 20 can be reduced, the component cost can be suppressed. Further, since the side wall portion 27 of the cap-like support 21 is fixed by welding to the side surface of the terminal protruding portion 12, even if a load is applied to the PTC element unit 20 in the lateral direction, the fixed position of the PTC element unit 20 is fixed. It is possible to avoid problems such as slippage. Furthermore, the cap-shaped support body 21 constituting the PTC element unit 20 can collect current three-dimensionally from the side surface in addition to the upper surface of the terminal protruding portion 12. For this reason, it is possible to suppress the influence of electrical resistance caused by mounting the PTC element unit 20 to the terminal 11. Thus, by mounting the PTC element unit 20 on the lithium battery 10, the overcurrent of the lithium battery 10 can be reliably prevented.

  (2) In the PTC element unit 20 of the present embodiment, since the PTC element 22 is formed in a disk shape and has the through hole 35 at the center thereof, the weight of the PTC element 22 can be reduced. Further, when the lead plate 37 is welded and fixed to the central portion of the external connection terminal plate 23, the PTC element 22 is disposed avoiding the central portion where heat is easily applied. Deterioration can be prevented.

  (3) In the PTC element unit 20 of the present embodiment, the side wall portion 27 of the cap-shaped support body 21 is divided into a plurality of pieces with the notch portion 29 therebetween. In this case, at the time of projection welding, the side wall 27 of the cap-shaped support 21 can be easily bent toward the terminal protrusion 12, and the side wall 27 can be reliably brought into contact with the side surface of the terminal protrusion 12. In addition, since the welding electrode can be disposed at the position of the notch 29, resistance welding can be reliably performed. Furthermore, when the side wall 27 of the cap-shaped support 21 is welded, heat is not easily transmitted to the PTC element 22 provided on the top plate 26 of the cap-shaped support 21, so that the performance deterioration of the PTC element 22 can be prevented. . Further, when the top plate 26 of the cap-shaped support 21 is welded, it is necessary to install the PTC element 22 while avoiding the welded portion on the top plate 26, so that the installation space for the PTC element 22 is reduced. On the other hand, in the present embodiment, the side wall 27 of the cap-shaped support 21 is welded, and the top plate 26 has the same dimensions as the terminal protrusion 12, so that a sufficient installation space for the PTC element 22 is ensured. be able to.

  (4) In the PTC element unit 20 of the present embodiment, a plurality of projection welding projections 30 are formed on the inner surface of the side wall portion 27 so as to face each other with the center of the cap-shaped support 21 interposed therebetween. The side wall portion 27 can be reliably welded to the side surface of the terminal protruding portion 12.

  (5) In the PTC element unit 20 of the present embodiment, since the concave portion 28 is formed on the first main surface 24 of the top plate 26 of the cap-shaped support body 21, the PTC element 22 is securely placed at the position of the concave portion 28. The PTC element 22 and the cap-shaped support 21 can be easily connected by soldering. Furthermore, according to this configuration, even if a lateral load is applied to the PTC element unit 20, it is possible to avoid the problem that the PTC element 22 falls off the cap-shaped support 21.

  (6) In the PTC element unit 20 of the present embodiment, an R-shaped lead-in portion 31 is formed at the tip of the side wall portion 27 of the cap-shaped support 21 so as to spread outward. If it does in this way, the cap-shaped support body 21 of the PTC element unit 20 can be easily fitted in the terminal protrusion 12.

  (7) In the lithium battery 10 of the present embodiment, the PTC element unit 20 is mounted on the terminal protruding portion 12 of the terminal 11 and can be connected to an external device via the PTC element unit 20. In this case, a steel plate that omits the surface plating treatment can be used as the steel plate that is a material for forming the terminal protruding portion 12, and the material cost of the lithium battery 10 can be suppressed.

  In addition, you may change embodiment of this invention as follows.

  In the external PTC element unit 20 of the above embodiment, the cap-shaped support 21 and the PTC element 22 are connected by soldering, and the PTC element 22 and the external connection terminal plate 23 are connected by soldering. However, instead of soldering, a conductive adhesive or the like may be used for connection.

  In the PTC element unit 20 of the above embodiment, the lead plate 37 is welded to the external connection terminal plate 23, but the terminal of the external device is connected to the external connection terminal plate 23 in a state where the lead plate 37 is not connected. You may connect directly to. In this case, since heat due to welding is not applied to the central portion of the PTC element 22, the PTC element unit 20 may be configured using a disk-like PTC element 22 in which the through hole 35 is not formed. Further, in the PTC element unit 20, the top plate 26, the PTC element 22, and the external connection terminal plate 23 of the cap-shaped support 21 are formed in a disk shape, but these shapes are the terminal protruding portions 12 of the terminals 11. It can change suitably according to the shape.

  In the PTC element unit 20 of the above embodiment, the notch 29 is provided in the side wall 27 of the cap-like support 21. However, the notch 29 may be omitted and the side wall 27 connected in an annular shape may be used. In the PTC element unit 20, the side surface of the PTC element 22 is exposed to the outside, but the side surface of the PTC element 22 may be covered with a protective film made of a sealing resin or the like. .

  In the present embodiment, the external PTC element unit 20 is attached to the cylindrical lithium battery 10, but the present invention is not limited to this. For example, the PTC element unit 20 may be attached to another battery such as a nickel-cadmium battery or a nickel-hydrogen battery. Moreover, you may attach the PTC element unit 20 to a button battery. In this case, the top plate 26 of the cap-shaped support 21 is formed with the same dimensions as the button battery, and the PTC element unit 20 is formed so that the side wall 27 of the cap-shaped support 21 is connected to the side surface of the button battery. To do.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiments described above are listed below.

  (1) An external PTC element unit that can be attached to a button battery, having a first main surface and a second main surface, and having a size and shape equivalent to the button battery in plan view, It is a plate having a cap-like support formed by using a conductive material, a device back surface and a device surface, and a side wall portion projecting vertically from the outer peripheral portion of the second main surface of the top plate. A PTC element having the element back surface bonded and fixed on the first main surface of the top plate, and an external connection terminal plate bonded and fixed on the element surface to cover the PTC element, The external PTC element unit, wherein the side wall portion can be connected to a side surface of the button battery in a state where the second main surface side of the plate is disposed opposite to an end surface on one side of the button battery.

  (2) A button battery to which the external PTC element unit according to the technical idea (1) is attached.

  (3) The external PTC element unit according to any one of the means 1 to 6, wherein the height of the side wall portion is lower than the height of the terminal protruding portion of the battery to be attached.

  (4) The external PTC element unit according to any one of means 1 to 6, wherein an R-shaped lead-in portion is formed at the tip of the side wall portion so as to spread outward.

  (5) An external PTC element unit characterized in that, in the means 5, the distance between the two projection welding projections facing each other is narrower than the diameter of the terminal protrusion.

DESCRIPTION OF SYMBOLS 10 ... Lithium battery as a battery 11 ... Terminal 12 ... Terminal protrusion part 20 ... PTC element unit 21 ... Cap-shaped support body 22 ... PTC element 23 ... External connection terminal board 24 ... 1st main surface 25 ... 2nd main surface 26 DESCRIPTION OF SYMBOLS ... Top plate 27 ... Side wall part 28 ... Concave part 29 ... Notch part 30 ... Projection for projection projection 33 ... Element surface 34 ... Element back surface 35 ... Through-hole 37 ... Lead plate as a conductive member

Claims (7)

An external PTC element unit that can be attached to a battery having a terminal protrusion at the center of the terminal,
A top plate having a first main surface and a second main surface and having a size and shape equivalent to that of the terminal projecting portion in plan view, and vertically projecting from an outer peripheral portion of the second main surface of the top plate And a cap-like support formed using a conductive material.
A PTC element having an element back surface and an element surface, the element back surface side being bonded and fixed to the first main surface of the top plate;
An external connection terminal plate bonded and fixed on the surface of the element so as to cover the PTC element, and in a state where the second main surface side of the top plate is disposed opposite to the upper end surface of the terminal protruding portion, An external PTC element unit, wherein a side wall portion is connectable to a side surface of the terminal protruding portion.   The external PTC element unit according to claim 1, wherein the PTC element has a disk shape having a through hole in a central portion.   A conductive member is laminated on the surface of the external connection terminal plate in a state where a part of the external connection terminal plate protrudes from the external connection terminal plate, and the conductive member is disposed at the center of the external connection terminal plate. The external PTC element unit according to claim 2, wherein the external PTC element unit is fixed by welding to the portion.   The external PTC element unit according to any one of claims 1 to 3, wherein the side wall portion of the cap-shaped support body is divided into a plurality of pieces with a notch portion therebetween.   5. A plurality of projection welding projections are formed on the inner surface of the side wall portion divided into a plurality of pieces so as to face each other across the center of the cap-shaped support. External PTC element unit.   6. The concave portion is formed in the first main surface of the top plate of the cap-shaped support, and the PTC element is disposed in the concave portion and soldered. The external PTC element unit according to item 1.   A battery to which the external PTC element unit according to any one of claims 1 to 6 is attached.

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