Externally-attached PTC element and tubular battery

Abstract

An externally-attached PTC element attachable to one electrode terminal of a tubular battery with electrode terminals on both end surfaces, the externally-attached PTC element including: a bottom plate made of a metal plate; a plate-shaped PTC element; and a top panel made of a metal plate, the plate-shaped PTC element and the top panel being stacked in that order above the bottom plate disposed below, the PTC element being disposed in an opposed area between the top panel and the bottom plate, the top panel projecting and extending in one direction with respect to a planar area of the bottom plate, the top panel having a distal end formed into a lead terminal shape mountable to a circuit board.

Claims

1. A tubular battery, an externally-attached positive temperature coefficient (PTC) element attached to the tubular battery, and a lead terminal plate, wherein: the tubular battery comprises: a first electrode terminal, and a second electrode terminal; and the externally-attached PTC element includes: a bottom plate made of a metal plate, the bottom plate being attached to the first electrode terminal of the tubular battery; a plate-shaped PTC element, and a top panel made of a metal plate, the plate-shaped PTC element and the top panel being stacked in that order above the bottom plate disposed below, the plate-shaped PTC element being disposed in an opposed area between the top panel and the bottom plate, the top panel extending in a first direction with respect to a planar area of the bottom plate, the top panel having a distal end formed into a single lead pin mountable to a circuit board; wherein the lead terminal plate is attached to the second electrode terminal of the tubular battery and is made of a metal plate extending linearly in the first direction, the lead terminal plate having a distal end formed into two lead pins inserted into respective through-holes on the circuit board, whereby the tubular battery cannot be mounted in an erroneous direction.

2. The tubular battery, the externally-attached PTC element attached to the tubular battery, and the lead terminal plate according to claim 1, wherein the bottom plate of the externally-attached PTC element has a lower surface with a shape along a planar shape of the first electrode terminal of the tubular battery, and an area on a top surface of the bottom plate that is exposed as an area to be welded to the first electrode terminal.

3. The tubular battery, the externally-attached PTC element attached to the tubular battery, and the lead terminal plate according to claim 2, wherein: the tubular battery has a cylindrical shape, the tubular battery includes a base-shaped convex portion on the first electrode terminal, the base-shaped convex portion being formed concentrically with an outer circumferential circle of the first electrode terminal, and the bottom plate of the externally-attached PTC element includes a concave portion on the lower surface, the base-shaped convex portion of the first electrode terminal of the tubular battery being inserted into the concave portion of the bottom plate.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a drawing illustrating an example of a conventional externally-attached PTC element.

(2) FIG. 2A is a drawing illustrating another example of a conventional externally-attached PTC element.

(3) FIG. 2B is a drawing illustrating the other example of the conventional externally-attached PTC element.

(4) FIG. 3A is a drawing illustrating an externally-attached PTC element according to an embodiment of the present invention.

(5) FIG. 3B is a drawing illustrating the externally-attached PTC element according to the embodiment of the present invention.

(6) FIG. 4 is a drawing illustrating a cylindrical battery to which the externally-attached PTC element according to the embodiment is attached.

(7) FIG. 5 is a drawing illustrating the externally-attached PTC element according to the embodiment having another terminal shape.

(8) FIG. 6A is a drawing illustrating a cylindrical battery to which an externally-attached PTC element according to a modification of the embodiment is attached.

(9) FIG. 6B is a drawing illustrating the cylindrical battery to which the externally-attached PTC element according to the modification of the embodiment is attached.

(10) FIG. 7A is a drawing illustrating an externally-attached PTC element according to a modification.

(11) FIG. 7B is a drawing illustrating the externally-attached PTC element according to the modification.

(12) FIG. 7C is a drawing illustrating the externally-attached PTC element according to the modification.

(13) FIG. 8 is a drawing illustrating an application form of the externally-attached PTC element according to the modification.

(14) FIG. 9A is a drawing illustrating an externally-attached PTC element according to another embodiment of the present invention.

(15) FIG. 9B is a drawing illustrating the externally-attached PTC element according to the other embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Cross-Reference to Related Applications

(16) This application claims priority upon Japanese Patent Application No. 2014-263897 filed on Dec. 26, 2014, which is herein incorporated by reference.

(17) The following describes embodiments of the present invention with reference to the attached drawings. Like reference numerals designate corresponding or identical elements in the drawings used for the following description, and therefore such elements may not be further elaborated. While a reference numeral is assigned to a part in a drawing, if unnecessary, the reference numeral may not be assigned to the corresponding part in another drawing.

Embodiments

(18) The embodiment of the present invention is an externally-attached PTC element that is to be attached to a tubular battery having both end surfaces as electrode terminals, for example, a cylindrical battery.

(19) FIG. 3A and FIG. 3B are drawings illustrating a structure of an externally-attached PTC element 1a according to the embodiment. FIG. 3A is a plan view when the PTC element 1a is viewed from upward. FIG. 3B is a cross-sectional view taken along an arrow a-a in FIG. 3A.

(20) The externally-attached PTC element 1a according to the embodiment, similar to the conventional externally-attached PTC elements (101, 102), has a basic structure of sandwiching a PTC element 10 with two metal plates (20, 30). However, the externally-attached PTC element 1a differs from the conventional externally-attached PTC elements (101, 102) in a planar shape of the metal plate (20, 30).

(21) The following designates the metal plate 30 in contact with an electrode terminal 111 of a cylindrical battery 110 between the two metal plates (20, 30) sandwiching the PTC element 10 as the bottom plate 30. The metal plate 20 opposed to the bottom plate 30 via the PTC element 10 is also referred to as the top panel 20. Respective directions, upper and lower directions in the externally-attached PTC element 1a, are defined assuming that the bottom plate 30 is disposed below while the PTC element 10 and the top panel 20 are stacked in this order above the bottom plate 30.

(22) As illustrated in FIG. 3A and FIG. 3B, in the externally-attached PTC element 1a according to the embodiment (hereinafter also referred to as the external PTC element 1a), a distal end side 21 of the top panel 20 is processed into a shape directly mountable on a circuit board. In this example, the distal end side 21 of the top panel 20 has a lead pin shape inserted into a through-hole.

(23) As illustrated in FIG. 3B, the external PTC element 1a has a structure of sandwiching the PTC element 10 as the chip component (hereinafter also referred to as the PTC chip 10) between a base end side 22 of the top panel 20 and the bottom plate 30.

(24) The external PTC element 1a illustrated here includes the top panel 20 and the bottom plate 30 both formed of a nickel plate having a thickness of 0.3 mm. The PTC element 10 is a so-called PolySwitch where a conductive polymer with a property of increasing an electrical resistance at high temperature is sandwiched with metal foils such as aluminum foils and has a thickness of 0.22 mm. The metal foil of the top panel 20 and the PTC element 10 and the metal foil of the bottom plate 30 and the PTC element 10 are bonded by a method such as a reflow soldering.

(25) The external PTC element 1a illustrated here is configured to be attached to the flat plate-shaped electrode terminal 111 in the cylindrical battery 110. That is, insofar as a general battery is used, the external PTC element 1a is attached to the electrode terminal corresponding to the negative electrode terminal (for convenience, hereinafter also referred to as an electrode terminal surface). Obviously, some industrial batteries incorporated in the electronic device and therefore cannot be exchanged by a user include terminals of both positive electrode and negative electrode having flat electrode terminal surfaces. In any cases, the bottom plate 30 has a disk shape along the planar shape of the electrode terminal 111 (electrode terminal surface). Viewing the external PTC element 1a from upward with the bottom plate 30 side as the lower side, the bottom plate 30 is not hid by the top panel 20 and an outer circumference side of the circular plate-shaped bottom plate 30 is exposed.

(26) FIG. 4 illustrates the external PTC element 1a attached to the cylindrical battery 110. In this example, the bottom plate 30 of the external PTC element 1a is attached to the electrode terminal 111 of the lithium primary battery 110 with outer dimensions of diameter =17 mm and a length L=33.5 mm. As illustrated in FIG. 4, the bottom plate 30 is welded and attached to the electrode terminal 111 at predetermined positions 34 in an outer circumference area of the circular plate.

(27) Here, the bottom plate 30 is attached to the electrode terminal 111 by spot welding. Obviously, another welding method such as a laser welding may be employed. Only a lead terminal plate 60 is attached to an electrode terminal 112, which is on an end surface 116 opposite to the electrode terminal 111, by a method such as the spot welding. In this example, to correctly implement the cylindrical battery 110 (hereinafter also referred to as the battery 110) on the circuit board, one lead pin is formed on the distal end side 21 of the top panel 20. Two lead pins are formed on a distal end side 61 of the lead terminal plate 60 on the electrode terminal 112 side. Inserting and soldering these lead pins into through-holes on the circuit board implements the cylindrical battery 110 on the circuit board.

(28) Accordingly, similar to various electronic components with lead pin, the cylindrical battery 110 is implemented occupying the minimum necessary area on the circuit board while short-circuit or a similar failure is reliably prevented and the implementation space is not overwhelmed. That is, this ensures further downsizing the electronic device incorporating the cylindrical battery 110. Obviously, similar to other implemented components, the implementation by reflow soldering is also possible, contributing to a cost reduction of electronic devices.

(29) The terminal shape of the distal end side 21 of the top panel 20 and the distal end side 61 of the lead terminal plate 60 is not limited to the above-described lead pin shape. For example, as illustrated in FIG. 5, cutouts (23, 63) into which edges of the circuit board are inserted may be formed.

Modifications

(30) The external PTC element 1a according to the above-mentioned embodiment is assumed to be attached to the electrode terminal 111 side having the flat surface in the cylindrical battery 110. However, for example, to secure the strength, although not as high as a positive electrode terminal in the general battery, a low-base-shaped convex portion whose surface is not a perfect flat surface but a concentric shape is formed on the electrode terminal 111 in some cases.

(31) FIG. 6A and FIG. 6B illustrate the cylindrical battery 110 formed on the electrode terminal 111 with a convex portion 113 (hereinafter also referred to as a circular convex portion 113 or a base-shaped convex portion 113) lower than the electrode terminal 112.

(32) FIG. 6A is a perspective view viewing the cylindrical battery 110 from the electrode terminal 111 side. FIG. 6B is a perspective view viewing the cylindrical battery 110 from the electrode terminal 112 side. The cylindrical battery 110 illustrated in FIG. 6A and FIG. 6B includes the circular convex portion 113 forming a concentric circle with an outer circumferential circle of the circular end surface of the cylindrical battery 110 on the electrode terminal 111. Meanwhile, the cylindrical battery 110 illustrated in FIG. 6A and FIG. 6B includes the electrode terminal 112 (hereinafter also referred to as the convex terminal 112) configured to be a column-shaped projection higher than the circular convex portion 113 on the other end surface 116.

(33) As a modification of the externally-attached PTC element 1a according to the above-mentioned embodiment, an external PTC element 1b attachable also to the electrode terminal 111 with the circular convex portion 113.

(34) FIG. 7A, FIG. 7B, and FIG. 7C illustrate the external PTC element 1b according to this modification. FIG. 7A is a plan view viewing the external PTC element 1b according to the modification from upward. FIG. 7B is a cross-sectional view taken along an arrow b-b in FIG. 7A. FIG. 7C is a cross-sectional view of the electrode terminal 111 with the circular convex portion 113 in the cylindrical battery 110, to which this external PTC element 1b is attached.

(35) As illustrated in FIG. 7A, the externally-attached PTC element 1b has the planar shape similar to the externally-attached PTC element 1a according to the above-mentioned embodiment when viewed from upward. Meanwhile, as illustrated in FIG. 7B, a concave portion 35 which is circularly opened to a lower surface 33 side of the bottom plate 30 is formed. As illustrated in FIG. 7C, when this external PTC element 1b is attached to the electrode terminal 111, the circular convex portion 113 of the electrode terminal 111 is inserted into this concave portion 35. Thus, a top end surface 114 of the circular convex portion 113 abuts on a bottom 36 of the concave portion 35.

(36) An outer-circumference-side top surface 115 of the electrode terminal 111 contacts the lower surface 33 of the bottom plate 30 on the outer circumference side. As illustrated in FIG. 8, the externally-attached PTC element 1b according to this modification having the deeper concave portion 35 is also applicable to the end surface 116 having the higher convex terminal 112 like the positive electrode terminal.

Other Embodiments

(37) Through welding of the bottom plate 30 to the electrode terminal 111, which is on the one end surface of the cylindrical battery 110, the externally-attached PTC element 1a according to the embodiment and the externally-attached PTC element 1b according to the modification are attached to the cylindrical battery 110. To achieve this, the bottom plate 30 has the circular plate shape wider than the top panel 20 with the distal end side 21 that also functions as the lead terminal. Then, the outer circumferential portion of the bottom plate 30 in contact with the electrode terminal 111 of the cylindrical battery 110 is spot-welded. Surely, the welding features a large attaching strength and a drop due to a vibration or a similar impact is less likely to occur. Meanwhile, the welding requires a dedicated welding machine. For example, in the case where an external PTC element is attached to a battery incorporated into an electronic circuit at a trial manufacture phase, it is not necessary to use the external PTC element assuming the welding. Thus, there may be the case where a further general-purpose external PTC element is required.

(38) FIG. 9A and FIG. 9B illustrate a general-purpose external PTC element 1c. FIG. 9A is a plan view of the general-purpose external PTC element 1c. FIG. 9B is a cross-sectional view taken along an arrow c-c in FIG. 9A. In the external PTC element 1c illustrated in FIG. 9A and FIG. 9B, the bottom plate 30 with a width equivalent to the top panel 20 is opposed to the base end side 22 of the top panel 20 with the distal end side 21 that also functions as the lead terminal. The PTC element 10 is disposed in the opposed area. It is only necessary to attach the lower surface 33 of the bottom plate 30 to the electrode terminal 111 using, a conductive adhesive, a solder, or the like.

(39) Thus, the external PTC element 1c illustrated in FIG. 9A and FIG. 9B can eliminate the need for welding; therefore, the external PTC element 1c is attachable not limited to the electrode terminal 111 but also to the convex terminal 112.

(40) The battery to which the external PTC elements 1a, 1b, and 1c according to the embodiments of the present invention are attached is not limited to the cylindrical battery 110. It is only necessary that the battery is a tubular battery whose both end surfaces serve as electrode terminals.

REFERENCE SIGNS LIST

(41) 1a, 1b, 1c, 101, 102 externally-attached PTC element 10 PTC element (PTC chip) 20 top panel (metal plate) 21 distal end side 22 base end side 30 bottom plate (metal plate) 33 lower surface 34 welding position 35 concave portion 36 bottom 40 solder 50 lead wire 60 lead terminal plate 61 distal end side 110 cylindrical battery 111 electrode terminal 112 electrode terminal (convex terminal) 113 circular convex portion (base-shaped convex portion) 114 top end surface 115 outer-circumference-side top surface 116 end surface 120 metal plate 130 metal plate 160 terminal plate 201 PTC element 220 metal plate (electrode plate) 221 distal end side 222 base end side 230 metal plate (electrode plate) 231 distal end side 232 base end side