Conductive member module and battery pack

A conductive member module includes a flat cable that includes a plurality of conductors and an insulating coating covering the conductors, a distal end part of each of the conductors being exposed from the coating, and a plurality of conductive members each of which includes a plate-shaped main body and a conductor holding part, the main body being connected to a portion of each of the conductors exposed from the coating by welding, the conductor holding part being separated from the main body at other sides except for one side connected to the main body by cutting in the main body and being folded back toward the main body to hold a portion of each conductor closer to a base end side than a part welded to the main body, the conductive members being continuously arranged along an extending direction of the flat cable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a conductive member module and a battery pack.

2. Description of the Related Art

Conventionally, there is known a technique of connecting a flat cable with a conductive member such as a busbar by welding. For example, Japanese Patent Application Laid-open No. 2011-210711 discloses a technique of placing a flexible flat cable on a busbar column and connecting an exposed conductor of the flexible flat cable with each busbar by welding.

Due to expansion and contraction of the flat cable caused by a temperature change, an external force is applied to a welded part between the conductor and the conductive member. It is desired to increase durability of a connection part between the conductive member and the conductor so that a connected state between the conductive member and the conductor of the flat cable is maintained even when such external force is applied.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a conductive member module and a battery pack that can improve durability of the connection part between a conductive member and a conductor of a flat cable.

In order to achieve the above mentioned object, a conductive member module according to one aspect of the present invention includes a flat cable that includes a plurality of conductors and an insulating coating covering the conductors, a distal end part of each of the conductors being exposed from the coating, and a plurality of conductive members each of which includes a plate-shaped main body and a conductor holding part, the main body being connected to a portion of each of the conductors exposed from the coating by welding, the conductor holding part being separated from the main body at other sides except for one side connected to the main body by cutting in the main body and being folded back toward the main body to hold a portion of the conductor closer to a base end side than a part welded to the main body, the conductive members being continuously arranged along an extending direction of the flat cable.

According to another aspect of the present invention, in the conductive member module, the conductor holding part may be wound around the conductor to hold the conductor.

According to still another aspect of the present invention, in the conductive member module, the conductor holding part may include a first holding part and a second holding part, and a distal end of the first holding part and a distal end of the second holding part may sandwich the conductor, and hold the conductor among the first holding part, the second holding part, and the main body.

A battery pack according to still another aspect of the present invention includes a battery module that includes a plurality of battery cells, a flat cable that includes a plurality of conductors and an insulating coating covering the conductors, a distal end part of each of the conductors being exposed from the coating, and a plurality of conductive members each of which includes a plate-shaped main body and a conductor holding part, the main body being connected to a portion of each of the conductors exposed from the coating by welding, the conductor holding part being separated from the main body at other sides except for one side connected to the main body by cutting in the main body and being folded back toward the main body to hold a portion of the conductor closer to a base end side than a part welded to the main body, the conductive members being continuously arranged along an extending direction of the flat cable.

DESCRIPTION OF EMBODIMENTS

The following describes a conductive member module and a battery pack according to embodiments of the present invention in detail with reference to the drawings. The present invention is not limited to the embodiments. Components in the following embodiments include a component that is easily conceivable by those skilled in the art or substantially the same component.

First Embodiment

The following describes a first embodiment with reference toFIGS. 1 to 8. The first embodiment relates to a conductive member module and a battery pack.FIG. 1is a perspective view of a battery pack according to the first embodiment of the present invention,FIG. 2is an exploded perspective view of the battery pack according to the first embodiment,FIG. 3is a plan view of a conductive member module according to the first embodiment,FIG. 4is a plan view of a busbar according to the first embodiment,FIG. 5is a perspective view of the busbar according to the first embodiment,FIG. 6is a perspective view illustrating a coupling state between the busbar and a flat cable according to the first embodiment,FIG. 7is a front view illustrating the coupling state between the busbar and the flat cable according to the first embodiment, andFIG. 8is a cross-sectional view illustrating the coupling state between the busbar and the flat cable according to the first embodiment.

As illustrated inFIGS. 1 and 2, a battery pack1according to the first embodiment includes a battery module10and a conductive member module20. The battery pack1is mounted on a vehicle such as an electric vehicle and a hybrid vehicle. The battery module10is an aggregate of a plurality of battery cells11. The conductive member module20is an aggregate of a plurality of busbars30and a flat cable40. The conductive member module20electrically connects the plurality of battery cells11in series or in parallel. The battery module10includes a housing (not illustrated) including an accommodation chamber for each battery cell11. Each battery cell11is accommodated in the accommodation chamber of the housing.

The battery cell11includes a cell main body12and a pair of electrode terminals13. The cell main body12has a rectangular shape. In the first embodiment, the cell main body12has a rectangular parallelepiped shape. The electrode terminals13are arranged on one face of the cell main body12. The battery module10is mounted such that a face12aof the cell main body12on which the electrode terminals13are arranged faces an upper side of the vehicle. In the following description, a face of the cell main body12on which the electrode terminals13are arranged is referred to as an “upper face12a”. A long side direction of the upper face12ais referred to as a “width direction”. The electrode terminals13are each a stud bolt projecting from the upper face12a, and are arranged on both ends in the width direction of the upper face12a. One of the pair of electrode terminals13is a positive electrode terminal, and the other one is a negative electrode terminal.

In the battery module10, the battery cells11are arranged at predetermined intervals along a direction orthogonal to the width direction. In the following description, a direction where the battery cells11are arranged is referred to as an “arrangement direction”. When the battery cells11are arranged along the arrangement direction, the electrode terminals13on one side of the battery cells11are arranged in a line along the arrangement direction, and the electrode terminals13on the other side of the battery cells11are arranged in a line along the arrangement direction. The arranged battery cells11virtually form a rectangular shape. Electrode terminal groups14each including the plurality of electrode terminals13are formed on one side and the other side in the width direction of the rectangular shape. In each electrode terminal group14, the positive and the negative electrode terminals13may be alternately arranged, or the electrode terminals13of the same polarity may be continuously arranged. In the battery module10according to the first embodiment, the electrode terminal group14is configured by the electrode terminals13of the same polarity.

The conductive member module20is an aggregate including the flat cable40and the busbars30. One conductive member module20is arranged for one electrode terminal group14. Thus, two conductive member modules20are arranged for one battery module10. To electrically connect the busbar30with the electrode terminal13, welding, screwing, and the like are used. In the first embodiment, when a nut50is fastened onto the electrode terminal13, the busbar30is physically and electrically connected to the electrode terminal13. More specifically, the electrode terminal13of the electrode terminal group14is inserted one by one into each insertion hole34in the busbars30of the conductive member module20. When the nut50is fastened onto the electrode terminal13, the busbar30is fastened to the battery cell11, and is electrically connected to the electrode terminal13.

As illustrated inFIG. 3, the flat cable40includes a plurality of conductors41and an insulating coating42that covers the conductors41. The conductor41is formed by a conductive material such as metal (for example, copper). The coating42is formed in a belt shape with an insulating synthetic resin and the like. In the coating42, the conductors41having a linear shape are arranged in parallel at intervals. A connector is connected to one end of the flat cable40. Each conductor41electrically connects the connector with each busbar30.

In the coating42, a groove43is arranged between adjacent conductors41along an extending direction of the flat cable40. A held part44is provided at an end of the coating42in the width direction. The held part44is a belt-shaped constituent part not including the conductor41therein. That is, the flat cable40includes a main body47and the held part44arranged on one side in the width direction of the main body47. The main body47is configured by the conductors41and the belt-shaped coating42including the conductors41therein. The held part44is a portion that is held by the busbar30and coupled to the busbar30, and functions as a rib for securing rigidity of the flat cable40. A plurality of through-holes44ais arranged in the held part44along the extending direction of the flat cable40. Two through-holes44aare arranged for each busbar30. The busbars30are arranged along the held part44.

The flat cable40is cut along the groove43to be separated into individual cable parts45. The cable part45is configured by the conductor41and a portion of the coating42that covers the conductor41. One end side (a side opposite to the connector) of the flat cable40is cut into a plurality of cable parts45having different lengths. At a distal end portion of each cable part45, the conductor41is exposed from the coating42. In the following description, in the cable part45, the conductor41exposed from the coating42is referred to as an “exposed part46”. The cable parts45are bent in a direction orthogonal to the extending direction of the flat cable40. The bent cable parts45are arranged at predetermined intervals along the extending direction of the flat cable40. In each bent cable part45, the exposed part46projects from the held part44in the width direction. Each cable part45is connected to the busbar30. By being connected to the cable parts45, the busbars30are continuously arranged at predetermined intervals along the extending direction of the flat cable40.

The busbar30is a conductive member made of a conductive material, and includes a busbar main body31, a conductor holding part32, and a cable holding part33as illustrated inFIGS. 4 and 5. The busbar main body31, the conductor holding part32, and the cable holding part33are integrally formed with each other. The busbar30according to the first embodiment is formed, for example, by punching a metal plate.FIGS. 4 and 5illustrate, by a solid line, the conductor holding part32and the cable holding part33on which folding processing (crimping) is performed. The conductor holding part32before folding processing is performed is illustrated inFIGS. 4 and 5by a chain double-dashed line.

The busbar main body31is a main body of the busbar30. The busbar main body31has a flat plate shape, and includes a first constituent part311and a second constituent part312. The first constituent part311is a constituent part having a rectangular plane shape. The second constituent part312is a constituent part having a substantially trapezoidal plane shape, and is connected to one end in a vertical direction of the first constituent part311. A “vertical direction” of the busbar30corresponds to the width direction in a state in which the conductive member module20is assembled to the battery module10(FIG. 1,FIG. 2). A “horizontal direction” of the busbar30is a direction orthogonal to the vertical direction, and corresponds to the arrangement direction in a state in which the conductive member module20is assembled to the battery module10. The second constituent part312has a tapered shape formed to have a width which narrows as getting away from the first constituent part311in the vertical direction.

The first constituent part311includes the insertion holes34into which the electrode terminals13are inserted. The insertion holes34are arranged on one end side and the other end side in the horizontal direction of the first constituent part311. Each insertion hole34passes through the first constituent part311in a thickness direction, and causes a space on a surface side of the first constituent part311to communicate with a space on a back surface side thereof. The busbar main body31includes a projection part35. The projection part35is arranged on one face (hereinafter, referred to as a “surface”)31aof the busbar main body31. The projection part35is arranged at a boundary part between the first constituent part311and the second constituent part312. The projection part35extends in the horizontal direction. A cross-sectional shape of the projection part35is an arc shape at a cross section orthogonal to the horizontal direction.

The conductor holding part32is a plate-shaped constituent part formed by cutting processing and the like. A plane shape of the conductor holding part32is a rectangle. An end32ain the horizontal direction of the conductor holding part32is connected to the second constituent part312. In the conductor holding part32, three sides of the rectangle including two long sides are cut and separated from the second constituent part312, and the other one side is connected to the second constituent part312.

The cable holding part33is a plate-shaped constituent part formed by cutting processing, notch processing, and the like. The cable holding part33includes a first cable holding part331projecting toward one side in the horizontal direction, and a second cable holding part332projecting toward the other side in the horizontal direction. A base end part33aof the first cable holding part331and the second cable holding part332is connected to a distal end312aof the second constituent part312. The cable holding parts331and332are separated from the second constituent part312by notch parts36extending in the horizontal direction.

As illustrated inFIGS. 6 and 7, the cable holding part33holds the held part44of the flat cable40. The first cable holding part331and the second cable holding part332are inserted into different through-holes44ato be bent, respectively, and sandwich the held part44. The cable holding parts331and332holds the held part44in such a manner that distal end parts331aand332athereof are bent inward to be opposed to each other in the horizontal direction. The cable holding part33regulates relative movement of the busbar main body31with respect to the flat cable40, and fixes the busbar main body31to the flat cable40.

The exposed part46is electrically connected to the projection part35by welding, and physically fixed to the projection part35. The exposed part46is, for example, connected to a center part in the horizontal direction of the projection part35. In the conductive member module20according to the first embodiment, part on a distal end side of the exposed part46is welded to the projection part35, and the distal end of the exposed part46projects toward the first constituent part311across the projection part35.

The conductor holding part32is folded back toward the busbar main body31, and holds a portion of the conductor41closer to the base end side than a part welded to the busbar main body31. In this case, the base end side of the conductor41indicates a side opposite to the distal end side in a direction along an axis of the conductor41, and typically indicates a connector side. The conductor holding part32according to the first embodiment holds the exposed part46, and is electrically connected to the exposed part46.

The conductor holding part32is folded back at an end32aserving as a base end part to hold the exposed part46. As illustrated inFIG. 7, the conductor holding part32according to the first embodiment is wound around the exposed part46to be folded back, and holds the exposed part46between itself and the busbar main body31. The conductor holding part32presses the exposed part46against the surface31aof the busbar main body31. Accordingly, the exposed part46is supported by the projection part35from one side in the thickness direction of the busbar main body31, and supported by the conductor holding part32from the other side thereof. The conductor holding part32wound around the exposed part46regulates not only movement of the exposed part46toward a direction getting away from the surface31a, but also movement of the exposed part46toward the extending direction of the flat cable40. Accordingly, when an external force is applied to the cable part45, the conductor holding part32holds the exposed part46against the external force, and regulates relative movement of the cable part45with respect to the busbar main body31and deformation of the cable part45. Thus, the conductor holding part32according to the first embodiment suppresses a change in stress or generation of an excessive stress at a welded portion between the projection part35and the exposed part46, and protects the welded portion.

As illustrated inFIG. 8, the conductor holding part32is wound around the exposed part46to be folded back, and holds the exposed part46with an inner surface of a curved part32b. An inner diameter of the curved part32bis sufficiently small to regulate relative movement of the exposed part46with respect to the busbar main body31. A size L1 of a gap between the distal end of the conductor holding part32and the surface31aof the busbar main body31is sufficiently smaller than an outer diameter of the exposed part46. The conductor holding part32holds the exposed part46to regulate movement of the exposed part46in the axial direction of the exposed part46or a direction intersecting with the axis thereof. Thus, when external force caused by bending, pulling, and the like is applied to the cable part45from the main body side of the flat cable40, the conductor holding part32regulates propagation of the external force toward the distal end side of the exposed part46across the conductor holding part32. That is, the conductor holding part32regulates propagation of the external force to the welded part between the exposed part46and the projection part35. The conductor holding part32also regulates deformation of the exposed part46when external force is applied to the cable part45.

Accordingly, the conductive member module20according to the first embodiment can improve durability of a connection part between the conductor41of the flat cable40and the busbar30, and improve stability of an electrically connected state. In the conductive member module20according to the first embodiment, the busbar30is electrically connected to the conductor41at two positions, that is, the projection part35and the conductor holding part32. Accordingly, durability of the connection part between the conductor41and the busbar30is increased, and a conduction failure is prevented.

As described above, the conductive member module20according to the first embodiment includes the flat cable40and the busbars30. The flat cable40includes the conductors41and the insulating coating42that covers the conductors41, and the distal end part of the conductor41is exposed from the coating42. The busbar30includes the busbar main body31and the conductor holding part32. The busbar main body31is a plate-shaped constituent part that includes the insertion holes34into which the electrode terminals13are inserted, and is connected, by welding, to the exposed part46of the conductor41exposed from the coating42. The conductor holding part32is integrally formed with the busbar main body31, and folded back toward the busbar main body31to hold a portion of the conductor41closer to the base end side than the part welded to the busbar main body31. The busbars30are continuously arranged along the extending direction of the flat cable40.

The conductor holding part32holds a portion of the conductor41closer to the base end side than the part welded to the busbar main body31. Accordingly, by suppressing stress variation in the welded part between the busbar main body31and the conductor41, the conductive member module20according to the first embodiment can improve durability of the connection part between the busbar30and the conductor41.

The conductor holding part32is wound around the conductor41to hold the conductor41. The conductor holding part32may hold the conductor41while being in contact with the conductor41, or may be wound around the coating42covering the conductor41to hold the conductor41via the coating42. By regulating relative movement of the conductor41with respect to the busbar main body31, the conductor holding part32wound around the conductor41can improve durability of the connection part between the busbar30and the conductor41.

The battery pack1according to the first embodiment includes the battery module10including the battery cells11, the flat cable40, and the busbars30. The flat cable40includes the conductors41and the insulating coating42that covers the conductors41, and the distal end part of the conductor41is exposed from the coating42. The busbars30each include the busbar main body31and the conductor holding part32, are continuously arranged along the extending direction of the flat cable40, and electrically connect the battery cells11in series or in parallel. The busbar main body31is a plate-shaped constituent part that includes the insertion holes34into which the electrode terminals13of the battery cell11are inserted, and is connected, by welding, to the exposed part46of the conductor41exposed from the coating. The conductor holding part32is integrally formed with the busbar main body31, and folded back toward the busbar main body31to hold a portion of the conductor41closer to the base end side than the part welded to the busbar main body31.

By suppressing stress variation in the welded part between the busbar main body31and the conductor41, the battery pack1according to the first embodiment can improve durability of the connection part between the busbar30and the conductor41.

The conductor holding part32may hold the conductor41covered by the coating42instead of holding the exposed part46. In other words, the conductor holding part32may hold the conductor41via the coating42.

Second Embodiment

The following describes a second embodiment with reference toFIGS. 9 to 12. In the second embodiment, components having the same function as that described in the first embodiment are denoted by the same reference numerals, and redundant description will not be repeated.FIG. 9is a plan view of the conductive member module according to the second embodiment,FIG. 10is a plan view of the busbar according to the second embodiment,FIG. 11is a perspective view illustrating a coupling state between the busbar and the flat cable according to the second embodiment, andFIG. 12is a front view illustrating the coupling state between the busbar and the flat cable according to the second embodiment.

The busbars30are formed, for example, by punching a metal plate. Each busbar30includes a conductor holding part37in place of the conductor holding part32in the first embodiment. InFIG. 10, a solid line indicates the conductor holding part37and the cable holding part33on which folding processing (crimping) is performed, and a chain double-dashed line indicates the conductor holding part37before folding processing is performed.

As illustrated inFIGS. 10 and 11, the conductor holding part37of the busbar30according to the second embodiment includes a first holding part371and a second holding part372. The first holding part371and the second holding part372each have a rectangular plane shape. As illustrated inFIG. 11, the first holding part371is arranged on one side in the extending direction of the flat cable40with respect to the exposed part46. The second holding part372is arranged on the other side in the extending direction of the flat cable40with respect to the exposed part46. In other words, as illustrated inFIG. 10, the first holding part371is arranged in a region on one side in the horizontal direction with respect to a center part35aof the projection part35, and the second holding part372is arranged in a region on the other side in the horizontal direction with respect to the center part35a. The conductor holding part37is formed, for example, by cutting processing. In each of the first holding part371and the second holding part372, three sides of the rectangle including two long sides are cut and separated from the second constituent part312, and the other one side closer to the center in the horizontal direction is connected to the second constituent part312.

The first holding part371and the second holding part372are folded back toward the busbar main body31, and hold a portion of the exposed part46on the base end side. The first holding part371is folded back toward the second holding part372at an end371aon the second holding part372side serving as a base end part. The second holding part372is folded back toward the first holding part371at an end372aon the first holding part371side serving as a base end part. As illustrated inFIG. 12, a distal end face371bof the folded-back first holding part371faces the surface31aof the busbar main body31. The distal end face371bpresses the exposed part46against the surface31a, and presses the exposed part46in the horizontal direction toward the second holding part372. A distal end face372bof the folded-back second holding part372faces the surface31a. The distal end face372bpresses the exposed part46against the surface31a, and presses the exposed part46in the horizontal direction toward the first holding part371. That is, the distal end of the first holding part371and the distal end of the second holding part372press the exposed part46against the surface31awhile sandwiching the exposed part46.

A portion on the distal end side of the exposed part46is connected to the projection part35by welding. That is, the exposed part46is supported by the projection part35. Accordingly, the exposed part46that is pressed against the surface31aby the first holding part371and the second holding part372is held among the distal end of the first holding part371, the distal end of the second holding part372, and the projection part35. As illustrated inFIG. 12, the first holding part371, the second holding part372, and the projection part35support the exposed part46from different three directions when viewed from the axial direction along the axis of the exposed part46. The first holding part371and the second holding part372regulate movement of the cable part45in the extending direction of the flat cable40, and regulate movement of the cable part45in a direction getting away from the surface31ain the thickness direction. Thus, the conductive member module20according to the second embodiment can regulate movement or deformation of the exposed part46against an external force applied to the cable part45, and improve durability of the connection part between the conductor41of the flat cable40and the busbar30.

The first holding part371and the second holding part372may press the exposed part46against the surface31aof the busbar main body31so that the exposed part46is sandwiched among the first holding part371, the second holding part372, and the surface31a. With such a configuration, the exposed part46can be held further firmly by the conductor holding part37. Additionally, the external force input from the main body side of the flat cable40is more securely prevented from propagating to the welded portion between the exposed part46and the projection part35.

As described above, in the conductive member module20according to the second embodiment, the conductor holding part37includes the first holding part371and the second holding part372. The distal end of the first holding part371and the distal end of the second holding part372sandwich the conductor41, and hold the conductor41among the first holding part371, the second holding part372, and the busbar main body31. Thus, the conductive member module20according to the second embodiment and the battery pack1including the conductive member module20can regulate relative movement of the conductor41with respect to the busbar main body31, and improve durability of the connection part between the busbar30and the conductor41.

Modifications of Embodiments

The following describes modifications of the first embodiment and the second embodiment. A method of connecting the busbar30to the battery cell11may be welding. In this case, the busbar30does not necessarily have the insertion holes34. A type of welding is not specifically limited. For example, ultrasonic welding, laser welding, and the like may be used.

The conductive member is not limited to the busbar30that connects the battery cells11to each other. The conductive member11may be, for example, a voltage detection terminal. The voltage detection terminal configures, together with the flat cable40and the like, a voltage detection circuit that detects voltage of the battery cell11and the battery module10. For example, the voltage detection terminal is electrically connected, by welding and the like, to the busbar that connects the battery cells11or the electrode terminal13. When the voltage detection terminal is used as the conductive member, the conductive member module20functions as a voltage detection module.

A conductive member module and a battery pack according to each of the present embodiments include, a flat cable including a plurality of conductors and an insulating coating covering the conductors, a distal end part of each of the conductors being exposed from the coating, and a plurality of conductive members. The conductive members each include a plate-shaped main body and a conductor holding part, and are continuously arranged along an extending direction of the flat cable, the main body being connected, by welding, to a portion of the conductor exposed from the coating, and the conductor holding part being separated from the main body at other sides except for one side connected to the main body by cutting in the main body and being folded back toward the main body to hold a portion of the conductor closer to a based end side than a part welded to the main body.

The conductive member module and the battery pack according to each of the present embodiments include a conductor holding part in which a main body of the conductive member holds the conductor not only at the welded part but also at a portion closer to the base end side than the welded part. The conductor holding part may hold the conductor while being in contact with the conductor, or may hold the conductor from the outside of the coating. The conductive member module and the battery pack according to the present embodiment can improve durability of the connection part between the conductive member and the conductor of the flat cable.

Contents disclosed in each of the embodiments and modifications described above can be appropriately combined to be implemented.