Patent Description:
The battery pack is formed as a single unit by covering, with a jacket (hereinafter, also referred to as a battery pack jacket) such as a heat-shrinkable tube, an assembled battery in which a plurality of cells is electrically connected in series or in parallel. Some battery packs are formed such that a plurality of cylindrical cells is disposed in parallel. <FIG> is an external view of a battery pack <NUM> in which an assembled battery formed by connecting three cylindrical cells (<NUM>, <NUM>, 910R) disposed in parallel is covered with a battery pack jacket <NUM>. <FIG> and <FIG> each illustrate an arrangement of the three cells (<NUM>, <NUM>, 910R) constituting the assembled battery illustrated in <FIG> and an electrical connection between the cells (<NUM> - <NUM>, <NUM> - 910R). Hereinafter, the respective cells <NUM>, <NUM> and 910R may also be referred to as the cell <NUM> where it is not necessary to distinguish between them.

As illustrated in <FIG>, the battery pack <NUM> is collectively covered with the battery pack jacket <NUM> formed of a heat-shrinkable tube in a state in which the three cells (<NUM>, <NUM>, 910R) are disposed in parallel. This maintains the arrangement of the cells (<NUM>, <NUM>, 910R). <FIG> is a perspective view illustrating a body of the battery pack (hereinafter, also referred to as a battery pack body <NUM>) excluding the battery pack jacket <NUM> from the battery pack <NUM> illustrated in <FIG>. <FIG> illustrates a state of the battery pack body <NUM> in the battery pack jacket <NUM> and corresponds to a plan view when the battery pack <NUM> illustrated in <FIG> is seen from the end surfaces of the cylindrical cells (<NUM>, <NUM>, 910R).

In the following, a configuration of the conventional battery pack <NUM> will be described based on <FIG> and <FIG>. Here, an axial direction <NUM> of each of cylindrical cell (<NUM>, <NUM>, 910R) is referred to as an up-down direction, and the directions orthogonal to the up-down direction are a right-left direction and a front-back direction. Here, an arrangement direction of the cells (<NUM>, <NUM>, 910R) is referred to as a right-left direction. Note that, each of the directions of "up-down", "right-left" and "front-back" is defined as shown in the drawings. That is, <FIG> illustrates a perspective view when the battery pack body <NUM> is seen from a right front upper side, and <FIG> illustrates a plan view when the battery pack <NUM> is seen from above.

First, as illustrated in <FIG> and <FIG>, the three cells (<NUM>, <NUM>, 910R) are disposed in parallel in the right-left direction. In this example, the three cells (<NUM>, <NUM>, 910R) are connected in series. Thus, the top and bottom ends of the adjacent cells (<NUM>-<NUM>, <NUM>-910R) are mutually inverted. Here, in both the right and left cells (<NUM>, 910R), negative terminals <NUM> face upward, and in the central cell <NUM>, a positive terminal <NUM> faces upward (note that, the respective terminals are also collectively referred to as electrode terminals (<NUM>, <NUM>) without distinguishing between the negative terminal <NUM> and the positive terminal <NUM>). On the upper end of the battery pack body <NUM>, the negative terminal <NUM> of the left end cell <NUM> and the positive terminal <NUM> of the central cell <NUM> are connected via a tab (hereinafter, also referred to as a connecting tab <NUM>) made of a metal plate. On the lower end (not shown) of the battery pack body <NUM>, the negative terminal of the central cell <NUM> and the positive terminal of the right end cell 910R are connected via another connecting tab <NUM> (not shown).

The connecting tab <NUM> is attached to each of the negative terminal <NUM> and the positive terminal <NUM>, for example, by welding (spot welding). Furthermore, lead wires (hereinafter, also referred to as power supply lead wires <NUM>) for supplying electric power to external devices are attached to the negative terminal <NUM> of the right end cell 910R and the positive terminal <NUM> (not shown) of the left end cell <NUM> via tabs (hereinafter, also referred to as power supply lead tabs <NUM>) different from the connecting tabs <NUM>.

Further, an axial-type protection element (such as a diode) <NUM> for preventing overdischarge is connected between the positive terminal <NUM> and the negative terminal <NUM> of each cell (<NUM>, <NUM>, 910R). The protection element <NUM> is configured such that lead wires (hereinafter, also referred to as element lead wires <NUM>) are guided from both the upper and lower ends of its body <NUM> along the up-down direction, and leading ends of the element lead wires <NUM> are connected to the positive terminal <NUM> and the negative terminal <NUM>, respectively, via the connecting tabs <NUM> or a dedicated tab (hereinafter, also referred to as an element tab <NUM>). Here, the element lead wires <NUM> and the power supply lead wires <NUM> are each connected to the corresponding tabs (<NUM>, <NUM>, <NUM>) by solder <NUM>.

Note that the three cells (<NUM>, <NUM>, 910R) disposed in parallel are held together by insulating adhesive tape <NUM> to maintain this arrangement. Accordingly, workability when the tabs (<NUM>, <NUM>, <NUM>) and the power supply lead wires <NUM> are attached before the battery pack jacket <NUM> is attached can be secured, and the element lead wires <NUM> of the protection element <NUM> are kept from contact with the battery can which also serves as one of the positive or negative electrodes, so as not to cause an external short-circuit. In order to further reliably prevent the short-circuit, an insulator (insulating tape <NUM> and a ring-shaped insulator <NUM> described later) such as adhesive tape is disposed in a region along the element lead wires <NUM> on the side surface of each cell (<NUM>, <NUM>, 910R), or on a border between the end surface and side surface of each cylindrical cell (<NUM>, <NUM>, 910R) and in its vicinity region or the like, as needed.

Furthermore, since the battery can of each cell (<NUM>, <NUM>, 910R) serves as one of the positive and negative electrodes, the cells (<NUM>, <NUM>, 910R) themselves are also covered with a cell jacket (not shown). In this example, in addition to the adhesive tape <NUM>, strip-shaped insulating tape <NUM> extending in a direction along the element lead wires <NUM> of the protection element <NUM> is bridged across the side surfaces of adjacent cells (<NUM>-<NUM>, <NUM>-910R). This prevents short-circuiting as described above, and for example, when the element lead wires <NUM> generate heat, the cell jacket (not shown) of each cell (<NUM>, <NUM>, 910R) is prevented from being torn by the heat so that a short-circuit does not occur due to contact of the element lead wires <NUM> with the battery can. Further, since there is a possibility that the cell jacket (not shown) near the border between the end surface and side surface of each cylindrical cell (<NUM>, <NUM>, 910R) may be torn by an edge of the connecting tab <NUM> that bridges the negative terminal <NUM> and the positive terminal <NUM> of the adjacent cells (<NUM>-<NUM>, <NUM>-910R) and a short-circuit caused thereby, a ring-shaped insulator <NUM> is disposed on the edges between cells (<NUM>-<NUM>, <NUM>-910R). In this example, the ring-shaped insulator <NUM> is disposed on the end surface where the projecting positive terminal <NUM> is located.

When the battery pack body <NUM> illustrated in <FIG> is covered with the battery pack jacket <NUM> formed of a heat-shrinkable tube, the external shape thereof is more firmly maintained, and the battery pack <NUM> illustrated in <FIG> and <FIG> is completed. It should be noted that the configuration of the battery pack is described, for example, in the following PTL <NUM> or the like.

As described above, in the battery pack <NUM> formed as a single unit by disposing a plurality of cylindrical cells <NUM> in parallel, when axial-type protection element <NUM> is attached, a process of bending the element lead wires <NUM> of the protection element <NUM> is required. The protection element <NUM> has a configuration in which the element lead wires <NUM> are guided to both ends of the tube-shaped element body <NUM>, and the leading ends of the element lead wires <NUM> are soldered via the tabs (<NUM>, <NUM>) on the end surfaces where the positive terminal <NUM> or the negative terminal <NUM> of the cell <NUM> is disposed. In other words, each element lead wires <NUM> is bent in the middle of its extension in a direction along the side surface from the end surface of the cell <NUM>. Accordingly, unless the bending shape of each element lead wire <NUM> and accuracy when the leading ends of the element lead wires <NUM> are attached to the tabs (<NUM>, <NUM>) are strictly managed, a displacement occurs in the attachment position of the protection element <NUM> and the arrangement of the element body <NUM>. Accordingly, the displacement of the protection element <NUM> leads to unevenness in external shape and dimension of the battery pack <NUM>. Further, it is necessary to attach the tabs (<NUM>, <NUM>) or the connecting tab <NUM> corresponding to the protection element <NUM> and the power supply lead wire <NUM> respectively to the areas of the electrode terminals (<NUM>, <NUM>) of the cell <NUM> which are limited and narrow, and it is difficult to attach a plurality of tabs (<NUM>, <NUM>, <NUM>) to one electrode terminal (<NUM>, <NUM>) depending on the size of the cylindrical cell <NUM>. Needless to say, the tabs (<NUM>, <NUM>) corresponding to the respective element lead wires <NUM> and the power supply lead wires <NUM> are required, thus increasing the number of parts. In addition, processes for attaching the respective tabs (<NUM>, <NUM>) are also required separately. For this reason, it becomes difficult to reduce manufacturing cost of the battery pack <NUM>.

As described above, the battery pack <NUM> formed as a single unit by disposing the plurality of cylindrical cells <NUM> in parallel separately needs a process of winding adhesive tape <NUM> around the assembled battery constituted by the plurality of cells <NUM> in the manufacturing process. Even though the adhesive tape <NUM> positions the cells in place, it is impossible to firmly fix the shape of the cell <NUM> by the adhesive tape <NUM>, and thus the relative positions of the cells <NUM> may be displaced due to vibration and impact in subsequent manufacturing processes such as attaching the various tabs (<NUM>, <NUM>, <NUM>). If the battery pack <NUM> is completed in a state in which the positional relationship of the cells <NUM> is displaced, there is a possibility that this may cause unevenness in external dimension of the battery pack <NUM>, and the battery pack <NUM> cannot be placed in an electronic device that uses the battery pack <NUM>. On the other hand, if the adhesive tape <NUM> is tightly wound around the assembled battery to prevent displacement, the adhesive tape <NUM> is linearly bridged across the V-shaped groove areas, and thus it becomes impossible to place the protection elements <NUM> into the V-shaped groove areas. Accordingly, when the battery pack body <NUM> is covered with the battery pack jacket <NUM>, the protection element <NUM> protrudes markedly from the outer periphery of the battery pack <NUM>. That is, the external shape of the battery pack <NUM> becomes unnecessarily large.

Moreover, in the battery pack <NUM>, the insulating tape <NUM> and the ring-shaped insulator <NUM> are attached in order to protect a cell jacket (not shown) of the cell <NUM> from the element lead wires <NUM> of the axial-type protection element <NUM> and the edge of the connecting tab <NUM>. Thus, it has been difficult to inexpensively provide the battery pack <NUM> due to the cost related to these members <NUM>, <NUM> and the process of attaching these members <NUM>, <NUM>.

In view of the aforementioned problems, an objective of the present disclosure is to provide an inexpensive battery pack with no variation in external dimension while securing dimensional accuracy of the battery pack and reducing manufacturing cost by decreasing the number of processes and parts.

The present disclosure to achieve the above-mentioned objective is an arrangement of protection element attachment tabs as set forth in claim <NUM>.

According to the present disclosure, dimensional accuracy of the battery pack can be secured, and manufacturing cost can be reduced by decreasing the number of processes and parts. Thus, it is possible to provide an inexpensive battery pack with no variation in external dimension. Other effects will be apparent in the following description.

This application claims the benefit of priority to <CIT> and <CIT>.

The following describes working examples of the present disclosure 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.

<FIG> illustrates a planar shape of a protection element attachment tab (hereinafter, also referred to as an element tab <NUM>) associated with a working example of a first embodiment in the present disclosure. The element tab <NUM> is made of a single flat metal plate, and includes a plurality of protrusions (<NUM>, <NUM>) with respect to a planar region (hereinafter, also referred to as an attachment part <NUM>) that is each attached to the electrode terminals (<NUM>, <NUM>) of the cell <NUM> by welding or the like. In the illustrated element tab <NUM>, the attachment part <NUM> has a hexagonal planar shape, and a long protrusion (hereinafter, referred to as a first protrusion <NUM>) and short protrusions (hereinafter, second protrusions <NUM>) protrude from the attachment part <NUM>. Note that, the second protrusions <NUM> protrude in mutually opposite directions with respect to the attachment part <NUM>, and the first protrusion <NUM> protrudes in a direction intersecting with one of the second protrusions <NUM> at a predetermined angle θ.

The battery back associated with the working example of the first embodiment in the present disclosure is configured such that protection elements <NUM> are attached to the respective electrode terminals (<NUM>, <NUM>) of the plurality of cells <NUM> via the aforementioned element tabs <NUM>, and the protection elements <NUM> are covered with a battery pack jacket <NUM> together with the cells <NUM>. <FIG> and <FIG> each illustrate a battery pack 11a associated with the working example of the first embodiment in the present disclosure. Here, when the directions of "up-down", "right-left" and "front-back" illustrated in <FIG>, <FIG> and <FIG> are employed, <FIG> is a perspective view when a battery pack body 12a excluding the battery pack jacket <NUM> from the battery pack 11a is seen from a right front upper side. <FIG> is a plan view when the battery pack 11a is seen from above. As illustrated in <FIG>, each element tab <NUM> is attached such that the second protrusions <NUM> extend in the front-back direction. Here, each element tab <NUM> is attached such that the center of the attachment part <NUM> and the center of the end surface of each cell (<NUM>, <NUM>, 910R) match with each other. Further, a pair of element tabs (150u-150d) attached to both the upper and lower electrode terminals (<NUM>, <NUM>) of the cells (<NUM>, <NUM>, 910R) faces each other so that their planar shapes are vertically symmetrical with each other. Then, as also illustrated in <FIG>, each of the first protrusions <NUM> extends toward a V-shaped groove area <NUM> between the adjacent cells (<NUM>-<NUM>, <NUM>-910R), and is bent in the middle of its extension in a direction along the side surface of each cell (<NUM>, <NUM>, 910R). In a pair of element tabs (150u, 150d) that faces each other in the up-down direction in one cell (<NUM>, <NUM>, 910R), the first protrusions (<NUM>-<NUM>) that extend along the respective cells (<NUM>, <NUM>, 910R) extend, and the respective leading ends thereof face each other across a gap. The vertical length D of this gap is larger than the vertical length d of the body <NUM> of the protection element <NUM>, and the body <NUM> of the protection element <NUM> is disposed in the gap. Each element lead wire <NUM> is attached to an area from the bending position to the leading end of the first protrusion <NUM> by soldering, welding or the like. In this example, each element lead wire <NUM> is soldered to the first protrusion <NUM> in an area <NUM> illustrated by dots in <FIG>. Accordingly, in the battery pack 11a associated with the present working example, the element lead wires <NUM> of the protection element <NUM> can be connected between the positive and negative electrode terminals (<NUM>-<NUM>) of the respective cells (<NUM>, <NUM>, 910R) without being bent.

In the battery pack 11a illustrated here, the three cells (<NUM>, <NUM>, 910R) are electrically connected in series, and the electrode terminals (<NUM>, <NUM>) of the left end cell <NUM> and the central cell <NUM> are connected by a flat, rectangular connecting tab <NUM> on the upper surface side. On the lower surface side which is not illustrated, the electrode terminals of the central cell <NUM> and the right end cell 910R are connected by the similar connecting tab <NUM>. The connecting tab <NUM> is stacked on the element tabs <NUM> of the adjacent cells (<NUM>-<NUM>, <NUM>-910R) and is attached in a state of being bridged across the attachment parts (<NUM>-<NUM>) of the adjacent element tabs <NUM>. Needless to say, the element tab <NUM> may be stacked on the connecting tab <NUM>. Furthermore, in the electrode terminals (<NUM>, <NUM>) that correspond to the respective positive electrodes and the negative electrodes of the assembled battery made by electrically connecting the three cells (<NUM>, <NUM>, 910R), the power supply lead wires <NUM> are attached to the second protrusions <NUM> of the element tabs <NUM>.

When the battery pack body 12a illustrated in <FIG> is covered with the battery pack jacket <NUM> made of a heat-shrinkable tube, each protection element <NUM> is disposed at a predetermined position as illustrated in <FIG>. In the battery pack 11a using the element tabs <NUM> in this way, a bending process that may cause displacement is unnecessary for the linear element lead wires <NUM> in the axial-type protection element <NUM> in its manufacturing process. In addition, since the first protrusion <NUM> is properly disposed at a predetermined position along the side surface shape of each cell (<NUM>, <NUM>, 910R), the external shape and dimension of the battery pack 11a become uniform. The power supply lead wire <NUM> can be attached to the second protrusion <NUM>, and it is not necessary to provide a separate tab for attaching the power supply lead wire <NUM>. That is, the number of parts can be decreased, and thus it becomes possible to reduce manufacturing cost of the battery pack 11a. Needless to say, even if the outer diameter of each cell (<NUM>, <NUM>, 910R) is small, the power supply lead wire <NUM> can be reliably attached thereto.

As illustrated in <FIG> and <FIG>, by bending the first protrusions <NUM> of the element tabs (150u, 150d) facing each other in the up-down direction, at a predetermined bending position <NUM> shown by a dotted line in the drawings, when the element tabs (150u, 150d) are attached to the positive and negative electrode terminals (<NUM>, <NUM>) of each cell (<NUM>, <NUM>, 910R), it is only necessary to position each element tab so as to allow an area on the leading end from the bending position <NUM> of the first protrusion <NUM> to be along the side surface of each cell (<NUM>, <NUM>, 910R). Further, the element lead wire <NUM> of the protection element <NUM> can also be attached in advance. In the illustrated element tab <NUM>, the second protrusions <NUM> protrude in mutually opposite directions with respect to the attachment part <NUM>, and one of the second protrusions <NUM> intersects with the protruding direction of the first protrusion <NUM> at a predetermined angle θ. Then, when the protruding direction of the second protrusions <NUM> is allowed to match with the front-back direction orthogonal to the arrangement direction of the cells (<NUM>, <NUM>, 910R), the first protrusion <NUM> automatically extend in a predetermined direction.

The planar shape of the element tab <NUM> is not limited to the shape illustrated in the working examples, and appropriate planar shapes may be applicable, for example, such that one first protrusion <NUM> and one second protrusion <NUM> may be formed, or three second protrusions <NUM> may be formed. In any case, as long as one first protrusion <NUM>, which bends in the middle of its extension in a direction along the side surface of the cell <NUM>, and other second protrusion <NUM> protrude in a direction intersecting with each other, such a planar shape may be applicable. Needless to say, not only the power supply lead wire <NUM>, but also such as a signal line connected to an external voltage monitor or the like and various sensor parts attached to the battery pack 11a can be attached to the second protrusions <NUM>. The protection element <NUM> is not also limited to diode, and any element such as PTC or fuse may be applicable as long as it has a function to prevent overdischarge. In any case, it is sufficient if the protection element <NUM> is an axial-type protection element <NUM>.

Although the three cells (<NUM>, <NUM>, 910R) are disposed in a row in the right-left direction in the battery pack 11a associated with the aforementioned working example, the cells may be disposed in two rows. <FIG> illustrates an example of a battery pack 11b configured with six cells <NUM> arranged in parallel in three columns and two rows. Here, <FIG> is a plan view when the battery pack 11b is seen from above. In <FIG>, the planar shape of each of element tabs <NUM> attached to a left-front side cell <NUM> and a right-back side cell <NUM> is a planar shape which serves as obverse and reverse relation with respect to the other element tabs <NUM>.

As a first working example of a second embodiment in the present disclosure, an arrangement fixing component for collectively fixing the three cylindrical cells (<NUM>, <NUM>, 910R) disposed in parallel will be described. <FIG> illustrates a schematic configuration of a parallel fixing component <NUM> associated with the present working example. The parallel fixing component (hereinafter, also referred to as a fixing component <NUM>) described here is a bottomed cap-shaped component to be collectively attached to the three cylindrical cells (<NUM>, <NUM>, 910R) disposed in parallel. Note that, in the following drawings, the directions of "up-down", "right-left" and "front-back" are each defined in the same manner as in <FIG> and <FIG>.

Although only one fixing component <NUM> is illustrated in <FIG>, the fixing component <NUM> is used in pairs in one battery pack and mounted on the both upper and lower end surfaces of the battery pack. The fixing component <NUM> illustrated in <FIG> adapts to a state when it is mounted on the lower end surface of the battery pack. The fixing component <NUM> is an integrated molded article made of resin and includes a bottom <NUM> having a planar shape that includes end surface shapes of the three cylindrical cells (<NUM>, <NUM>, 910R) disposed in parallel on the left and right, and a barrel portion <NUM> formed by a wall surface having a predetermined height, the wall surface standing around the bottom <NUM>. Specifically, in a state illustrated in <FIG>, the bottom <NUM> has a planar shape formed by continuously arranging v-shaped groove areas <NUM> through recessed portions <NUM>, the V-shaped groove areas <NUM> each being formed between the cells (<NUM>-<NUM>, <NUM>-910R) and allowing three circles corresponding to the end surface shapes of the three cylindrical cells (<NUM>, <NUM>, 910R) disposed in parallel on the left and right to be mutually adjacent. In this example, the recessed portions <NUM> each have a round groove shape and allow the aforementioned V-shaped groove areas <NUM> to be smoothly continued. The barrel portion <NUM> is formed by the wall surface standing upwardly around the bottom <NUM> while maintaining the planar shape of the bottom <NUM>. In the fixing component <NUM> illustrated in <FIG>, the lower ends of the three cells (<NUM>, <NUM>, 910R) are collectively inserted to a space formed by an inner surface <NUM> of the barrel portion <NUM> and an upper surface <NUM> of the bottom <NUM>. Note that, the size of the fixing component <NUM> is set so that the cells (<NUM>, <NUM>, 910R) are inserted in a press-fitted state.

Furthermore, the bottom <NUM> is provided with opening portions <NUM> for allowing the electrode terminals (<NUM>, <NUM>) of the three cells (<NUM>, <NUM>, 910R) to be exposed outward. In addition, at positions corresponding to the recessed portions <NUM> of the bottom <NUM> in the barrel portion <NUM>, protruding piece portions <NUM> extending upward (that is, in the height direction in which the wall surface stands) are formed while maintaining the planar shapes of the recessed portions <NUM>. Note that, in the fixing component <NUM> described here, ribs <NUM> each extending from a leading end to the upper surface <NUM> of the bottom <NUM> are formed at the inner side of the protruding piece portions <NUM>, and the protruding piece portions <NUM> are reinforced by those ribs <NUM> so as not to be easily bent. Further, the protruding piece portions <NUM> each include an area <NUM> in which the outer surface on the leading end is molded into a stepped shape so as to extend inward and thus the leading end is made thin with respect to the base end.

A second working example of the second embodiment in the present disclosure is a battery pack 21a using the fixing component <NUM> associated with the aforementioned first working example. <FIG> each illustrate the battery pack 21a associated with the second working example. Here, an assembling procedure of the battery pack 21a is illustrated in <FIG>. First, as illustrated in <FIG>, two fixing components (<NUM>-<NUM>) are set opposite each other in the up-down direction so as to allow the respective leading ends of the protruding piece portions <NUM> to be opposed, and the three cells (<NUM>, <NUM>, 910R) are disposed in parallel between the two fixing components (<NUM>-<NUM>). Then, as illustrated in <FIG>, the fixing components <NUM> are fitted in the upper and lower end surfaces of the cells (<NUM>, <NUM>, 910R). Accordingly, the cells (<NUM>, <NUM>, 910R) are fixed in a parallel state while maintaining a correct relative positional relationship. Then, the electrode terminals (<NUM>, <NUM>) of each cell (<NUM>, <NUM>, 910R) are exposed from the opening portions <NUM> of the bottoms <NUM> of the fixing components <NUM>, and each of the protruding piece portions <NUM> is disposed in each of the V-shaped groove areas <NUM> between the adjacent cells (<NUM>-<NUM>, <NUM>-910R). The respective leading ends of the protruding piece portions <NUM> of the upper and lower fixing components <NUM> are closely opposed. In other words, the height from the bottom <NUM> of the fixing component <NUM> to the leading ends of the protruding piece portions <NUM> is approximately half the length of the battery can of each cell (<NUM>, <NUM>, 910R) in this example.

After the three cells (<NUM>, <NUM>, 910R) are fixed by the fixing components <NUM>, various tabs (<NUM>, <NUM>, <NUM>) are attached to the electrode terminals (<NUM>, <NUM>) of the cells (<NUM>, <NUM>, 910R), which are exposed from the opening portions <NUM> of the bottoms <NUM> as illustrated in <FIG>, and then the element lead wires <NUM> of the protection elements <NUM> and the power supply lead wires <NUM> are each attached to the corresponding tabs (<NUM>, <NUM>, <NUM>). When the protection elements <NUM> are attached, each element lead wires <NUM> are bent so as to be along the extending direction of the protruding piece portions <NUM>, and then both ends of the element lead wires <NUM> are attached to predetermined tabs (<NUM>, <NUM>) by solder <NUM>. Accordingly, the body <NUM> of the protection element <NUM> of enlarged diameter conforms to the shape of the recessed portion <NUM>, so that the element body <NUM> is kept from markedly protruding in the front-back direction with respect to each cell (<NUM>, <NUM>, 910R). In addition, the leading end of each of the protruding piece portions <NUM> is a thin-walled area (hereinafter, also referred to as a thin-walled portion <NUM>), and the element body <NUM> is disposed along the thin-walled portion <NUM>, thereby further suppressing the protrusion of the element body <NUM> in the front-back direction. After the battery pack body 22a is assembled in this way, the battery pack body 22a is covered with the battery pack jacket <NUM> made of a heat-shrinkable tube to complete the battery pack 21a. <FIG> is a plan view when the battery pack 21a is seen from above. Each body <NUM> of the protection element <NUM> is disposed along the outer surface shape of the round groove shape of the protruding piece portion <NUM> of the fixing component <NUM>, and the front-back and right-left side surfaces of the battery pack 21a is molded into a shape that allows the outer periphery of the cells (<NUM>, <NUM>, 910R) disposed in parallel to be smoothly continued. In other words, there is no unnecessary protruded area caused by the thickness of the element body <NUM> on the outer surface of the battery pack jacket <NUM>, and the external dimension of the battery pack 21a is restricted to a required minimum. In the battery pack <NUM>, the shape of the cells (<NUM>, <NUM>, 910R) disposed in parallel is maintained by using deformable adhesive tape <NUM> before the protection elements <NUM> are attached, whereas in the battery pack 21a associated with the second working example of the present embodiment, the cells (<NUM>, <NUM>, 910R) are collectively fixed by using the fixing components <NUM> formed of an integrated molded article made of resin, which is hardly deformed. Each element body <NUM> is also disposed along the outer surface of the protruding piece portion <NUM> which is hardly deformed. Thus, even when the battery pack jacket <NUM> made of a heat-shrinkable tube is covered on the battery pack body 22a, the shape of the battery pack body 22a does not deform, and this allows unevenness in external shape and dimension of the battery pack 21a to be extremely reduced. Furthermore, since the element lead wires <NUM> of the protection element <NUM> extend along the protruding piece portions <NUM>, the cell jacket (not shown) of the cells (<NUM>, <NUM>, 910R) can be reliably protected from the heat of the element lead wires <NUM>. Also, the cell jacket (not shown) near the border between the end surface and side surface of each of the cylindrical cells (<NUM>, <NUM>, 910R) is protected from the edge of the connect tab <NUM> by the outer bottom of the fixing component <NUM>. In the battery pack 21a associated with the second working example of the present embodiment, it is also possible to reduce a cost of members such as strip-shaped insulating tape (in <FIG>, reference number <NUM>) in the battery pack <NUM> and a ring-shaped insulator (in <FIG>, reference number <NUM>), and a cost of process of attaching these members <NUM> and <NUM>.

In the battery pack <NUM>, when the axial-type protection elements <NUM> are attached, a process of bending the element lead wires <NUM> of the protection elements <NUM> is required. The protection elements <NUM> are each configured so that the element lead wires <NUM> are guided to both ends of the element body <NUM>, and the leading ends of the element lead wires <NUM> are soldered through the tabs (<NUM>, <NUM>) on the end surfaces on which the electrode terminals (<NUM>, <NUM>) are disposed in the cell <NUM>. In other words, each element lead wire <NUM> is bent in the middle of its extension in a direction along the side surface from the end surface of the cell <NUM>. Accordingly, unless the bending shape of each element lead wire <NUM> and accuracy when the leading ends of the element lead wires <NUM> are attached to the tabs (<NUM>, <NUM>) are strictly managed to a certain extent, a displacement occurs in the attachment position of the protection elements <NUM> and the arrangement of the element bodies <NUM>. The displacement of the protection elements <NUM> leads to unevenness in external shape and dimension of the battery pack <NUM>. Further, it is necessary to attach the tabs (<NUM>, <NUM>) or the connecting tab <NUM> corresponding to the protection element <NUM> and the power supply lead wire <NUM> respectively to the areas of the electrode terminals (<NUM>, <NUM>) of the cell <NUM> which are limited and narrow. When the outer diameter of the cell <NUM> is small, it becomes difficult to attach the tabs (<NUM>, <NUM>) corresponding to the protection element <NUM> and the power supply lead wire <NUM>, respectively. For this reason, a battery pack also having a structure capable of preventing a displacement when the axial-type protection elements <NUM> are attached is exemplified as a third working example of the present embodiment.

<FIG> is a drawing for explaining a schematic configuration of a battery pack 21b associated with the third working example of the present embodiment. Here, <FIG> illustrates a perspective view when the battery pack body 22b to which an exterior tube is not mounted is seen from the left front upper side. As illustrated in <FIG>, the battery pack 21b associated with the third working example is configured to include the element tabs <NUM>. The element tabs <NUM> are each made of a single flat metal plate, and are attached to the positive and negative electrode terminals (<NUM>, <NUM>) of each cell (<NUM>, <NUM>, 910R) by welding or the like. Then, power supply lead wires <NUM> and element lead wires <NUM> of protection elements <NUM> are each attached to the predetermined element tabs <NUM> by soldering or the like.

Each element tab <NUM>, as illustrated in <FIG> and <FIG>, includes a plurality of protrusions (<NUM>, <NUM>) with respect to the attachment part <NUM> that is each attached to the electrode terminals (<NUM>, <NUM>) of each cell (<NUM>, <NUM>, 910R) by welding, one protrusion <NUM> is bent in the middle of its extension in the up-down direction along the protruding piece portion <NUM> of the fixing component <NUM>. Each element tab <NUM> illustrated in <FIG> includes a long protrusion (first protrusion <NUM>) and short protrusions (second protrusions <NUM>), the second protrusions <NUM> protrude in mutually opposite directions from the hexagonal attachment part <NUM>, and the first protrusion <NUM> protrudes in a direction intersecting with the second protrusions <NUM>. Each element tab <NUM> is attached so that an extending direction of the second protrusions <NUM> is directed to the front-back direction, the first protrusion <NUM> extends toward a direction of the recessed portion <NUM> of the fixing component <NUM>, and is bent in the middle of its extension in a direction along the protruding piece portion <NUM>. The first protrusions <NUM> of the respective element tabs <NUM> attached to the electrode terminals (<NUM>, <NUM>) of the upper and lower ends of each cell (<NUM>, <NUM>, 910R) extend along the protruding piece portions <NUM> and their leading ends face each other with a predetermined gap. The vertical length D of this gap is larger than the vertical length d of the body <NUM> of the protection element <NUM>. The protection element <NUM> is disposed in the gap, and the element lead wires <NUM> are attached to the first protrusions <NUM> by soldering, welding or the like without being bent. In this example, the element lead wires <NUM> are attached by the solder <NUM>.

By covering the battery pack body 22b configured in this way with the battery pack jacket <NUM>, the battery pack 21b associated with the third working example is configured. In the battery pack 21b associated with the third working example, a process performing a bending process which causes displacement is unnecessary with respect to the linear element lead wires <NUM> of the axial-type protection element <NUM>. In addition, the power supply lead wire <NUM> can be attached to the second protrusion <NUM>, and it is unnecessary to separately provide the power supply lead tab <NUM> for attaching the power supply lead wire <NUM> and the element tab <NUM> for attaching the element lead wire <NUM>. Consequently, the number of parts can be decreased, and it becomes possible to reduce manufacturing cost of the battery pack 21b.

Note that, in the element tab <NUM> of the third working example, the second protrusions <NUM> protrude in mutually opposite directions with respect to the attachment part <NUM>, and the first protrusion <NUM> intersects with the protruding direction of one of the second protrusions <NUM> at the predetermined angle θ. This angle θ is set so that the first protrusion <NUM> automatically extends toward the area in which the protruding piece portion <NUM> is formed when the protruding directions of the second protrusions <NUM> are allowed to match with the front-back direction orthogonal to the arrangement direction of the cells <NUM>. Alternatively, if a shallow groove having a rectangular cross-section along which the first protrusion <NUM> is placed is formed on the outer surface of the bottom <NUM> of the fixing component <NUM>, the first protrusion <NUM> can correctly extend in a predetermined direction even if the arrangement direction of the cells <NUM> and the extending direction of the second protrusions <NUM> are not adjusted when each element tab <NUM> is attached to the electrode terminals (<NUM>, <NUM>).

In general, the cylindrical cell <NUM> includes the projecting positive terminal <NUM> and the flat negative terminal <NUM>, and the negative terminal <NUM> may not protrude outward from the bottom <NUM> of the fixing component <NUM> in some cases. In such a case, the first and second protrusions (<NUM>, <NUM>) interfere with the edge of the opening portion <NUM> of the bottom <NUM> when the attachment part <NUM> of the element tab <NUM> is attached to each of the electrode terminals (<NUM>, <NUM>). Thus, in response to such a case, the base ends of the first and second protrusions (<NUM>, <NUM>) may be bent into a crank shape in advance. Accordingly, the first and second protrusions (<NUM>, <NUM>) get over the edge of the opening portion <NUM> of the fixing component <NUM> and can be prevented from interfering with the edge of the opening portion <NUM> of the bottom <NUM>. In any case, the element tab <NUM> made of a flat metal plate may be easily molded into any shape by pressing or the like in advance.

In the aforementioned working examples, the protruding piece portions <NUM> of the fixing component <NUM> are formed so as to correspond to all of the V-shaped groove areas <NUM> between the adjacent cells (<NUM>-<NUM>, <NUM>-910R). However, any of the protruding piece portions <NUM> may be omitted as long as the number of protruding piece portions <NUM> is greater than or equal to the number of protection elements <NUM> that are attached to the battery packs 21a, 21b. Moreover, when a temperature sensor or the like on the surface of the cell <NUM> is stuck on the side surface of the cell <NUM> in the V-shaped groove area <NUM>, only the protruding piece portion <NUM> corresponding to the sticking position may be omitted. Note that, as long as the protection element <NUM> has a function preventing overdischarge, the protection element <NUM> is not limited to diode, and may be, for example, PTC or fuse. In any case, it is sufficient that the protection element <NUM> is an axial-type protection element <NUM>.

The element tab <NUM> of the third working example is not limited to the illustrated configuration, and may have a planar shape, for example, in which one first protrusion and one second protrusion (<NUM>, <NUM>) are formed, or three second protrusions <NUM> may be included. In any case, it is only necessary that one first protrusion <NUM>, which bends in the middle of its extension in a direction along the protruding piece portion <NUM> of the fixing component <NUM>, and other second protrusion <NUM> protrude in a direction intersecting with each other. Needless to say, not only the power supply lead wire <NUM>, but also such as a signal line connected to an external voltage monitor and various sensor parts attached to the battery packs 21a, 21b can be attached to the second protrusion <NUM>.

The fixing component <NUM> in the aforementioned working examples is configured so that the three cells (<NUM>, <NUM>, 910R) disposed in parallel in a row in the right-left direction are held together. However, as long as the cells are disposed in parallel, the number of cells <NUM> may be two, or four or greater. In addition, the cells <NUM> included in the battery pack are not limited to one row, and they may be disposed in parallel in two rows. <FIG> is a plan view illustrating a battery pack 21c configured with six cells <NUM> arranged in parallel in three columns and two rows (hereinafter, <NUM>×<NUM>) when the battery pack body 22c omitting the battery pack jacket <NUM> is seen from above. The fixing component <NUM> is collectively mounted on the end surfaces of the cells <NUM> disposed in parallel in three columns and two rows, and the V-shaped groove areas <NUM> between the adjacent cells (<NUM>-<NUM>) in the front-back direction are also continuous by recessed portions <NUM>. In this example, arc-shaped wall surfaces <NUM> standing upward (front side on the paper) are formed on the bottom <NUM>, and thus the cells <NUM> are reliably held by the barrel portion <NUM> and these arc-shaped wall surfaces <NUM>.

As stated above, the present embodiment has been described. According to the present embodiment, dimensional accuracy of the battery packs 11a, 11b, 21a and 21b can be secured, and manufacturing cost can be reduced by decreasing the number of processes and parts. Thus, inexpensive battery packs 11a, 11b, 21a and 21b can be provided with no variation in external dimension.

According to the tabs <NUM>, <NUM> for attaching protection elements associated with the present embodiment, in manufacturing processes of the battery packs 11a and 11b formed as a single unit in a state in which a plurality of cylindrical cells <NUM> are disposed in parallel, dimensional accuracy can be secured, and manufacturing cost can be reduced by decreasing the number of processes and parts. Consequently, inexpensive battery packs 11a and 11b can be provided with no variation in external dimension.

Claim 1:
A battery pack (11a, 11b) comprising:
a plurality of cylindrical cells (<NUM>) disposed in parallel;
a plurality of protection elements (<NUM>), each including a body (<NUM>) and a pair of element lead wires (<NUM>) extending from the body (<NUM>) to one side and another side, the protection elements (<NUM>) being configured to prevent overdischarge between a positive electrode terminal (<NUM>) formed on one end surface of each cell (<NUM>) of the plurality of cells (<NUM>) and a negative electrode terminal (<NUM>) formed on another end surface of each cell (<NUM>) of the plurality of cells (<NUM>); and
a pair of protection element attachment tabs (<NUM>, <NUM>) for attaching a protection element (<NUM>) to each cell of the plurality of cylindrical cells (<NUM>) constituting a battery pack (11a; 11b),
each protection element attachment tab (<NUM>, <NUM>) of the pair of protection element attachment tabs (<NUM>, <NUM>) being made of a single flat metal plate, and comprising:
a planar region (<NUM>) facing the end surface of the cell (<NUM>) ;
a first protrusion (<NUM>) protruding from the planar region (<NUM>) in a direction along the planar region (<NUM>) and having a length so that a leading end of the first protrusion (<NUM>) protrudes outward from the end surface of the cell (<NUM>); and
a second protrusion (<NUM>) protruding from the planar region (<NUM>) in a direction different from the first protrusion (<NUM>) along the planar region and being shorter than the first protrusion (<NUM>); wherein:
the first protrusion (<NUM>) of each of the pair of protection element tabs (<NUM>) extends toward a V-shaped groove area (<NUM>) formed between the cells (<NUM>) adjacent each other and bending in a direction along a side surface of each cell (<NUM>) of the plurality of cells (<NUM>),
the leading ends of the first protrusions (<NUM>) of each of the pair of protection element tabs (<NUM>, <NUM>) facing each other across a gap larger than a length of the body (<NUM>) of the protection element (<NUM>),
the body (<NUM>) of the protection element (<NUM>) being disposed in the gap, the pair of element lead wires (<NUM>) being attached to areas (<NUM>) in which the first protrusions (<NUM>) of the pair of protection element attachment tabs (<NUM>, <NUM>) extend along a side surface of each cell (<NUM>) of the plurality of cells (<NUM>).