Busbar module

A busbar module includes: a circuit body having a flexible circuit board; busbars; and a holder. The circuit body has: a band-shaped main strip to be located to extend in a stacking direction of cells; a band-shaped first branch strip branched from the main strip and extending toward a corresponding busbar; and a second branch strip branched from the main strip and extending toward an external device. The first branch strip has: a bent portion extending in the stacking direction and having a bent shape around an axis crossing the stacking direction; and a busbar connection portion disposed closer to an end of the first branch strip than the bent portion and connected to the corresponding busbar. The second branch strip has a device connection portion to be connected to the external device.

CROSS-REFERENCES TO RELATED APPLICATION(S)

This application is based on and claims priority from Japanese Patent Application No. 2019-112232 filed on Jun. 17, 2019, and the entire contents of which are incorporated herein by reference.

BACKGROUND

Field of the Invention

The present invention relates to a busbar module.

Description of Related Art

Conventionally, busbar modules are used in such a manner as to be attached to a battery assembly (i.e., a battery module in which plural battery cells are laid on each other) that is a drive power source installed in an electric vehicle, a hybrid vehicle, or the like.

The busbar module disclosed in Patent document 1 is equipped with plural busbars each of which connects a positive electrode and a negative electrode of adjacent ones of battery cells laid on each other and voltage detection lines that are connected to the respective busbars and serve to monitor the individual battery cells. The voltage detection lines are a bundle of plural electric wires each having a common structure that a core wire is covered with an insulating covering.

As for details of the above connector, refer to JP 2014-220128 A.

SUMMARY

Incidentally, in general, battery cells constituting a battery assembly extend and contract in the stacking direction due to heat generated in association with charging and discharging, an environment temperature, etc. As a result, the battery assembly (battery module) is also deformed, that is, extends and contracts, in the battery cells stacking direction. Furthermore, in general, the size of a battery assembly in the stacking direction may vary from one battery assembly manufactured to another (manufacture dispersion) due to an assembling allowance of stacking of plural battery cells. To accommodate such deformation of the battery assembly and manufacture dispersion, in general, busbar modules are designed in such a manner that the lengths of the voltage detection lines have certain margins.

However, in the above conventional busbar module, in the case where the number of battery cells laid on each other is increased to, for example, increase the capacity of the battery assembly, the number of electric wires constituting the voltage detection lines is also increased. As a result, when the voltage detection lines are formed by bundling such a large number of electric wires, the stiffness of all the voltage detection lines (and hence the stiffness of the busbar module) is increased, which makes it difficult to increase the efficiency of work of attaching the busbar module to the battery assembly (the ease of attachment). For the same reason, it may become difficult for the busbar module to extend and contract to absorb deformation and manufacture dispersion of the battery assembly sufficiently.

On the other hand, the location of an external device (e.g., voltage detection device) to which the electric wires of the voltage detection lines are connected and the structure of the external device itself may vary depending on, for example, the specifications of a battery assembly that employs the busbar module and a vehicle in which the battery assembly is installed. It is desirable that the busbar module be configured so as to be able to flexibly accommodate such various installation locations and structures of external devices, in other words, to increase the degree of freedom of selection of an installation location and a structure of an external device.

An object of the invention is to provide a busbar module that is high in the ease of attachment to a battery assembly and the followability to deformation and manufacture dispersion of the battery assembly and is also high in the degree of freedom of selection of an installation location and a structure of an external device.

Embodiments of the present invention provide the following items [1] to [5]:

[1] A busbar module to be attached to a battery assembly having a stack of a plurality of cells and to connect the plurality of the cells to an external device, the busbar module comprising:

a circuit body having a flexible circuit board including a wiring pattern; a plurality of busbars to be connected to corresponding electrodes of the plurality of the cells; and a holder holding the busbars and being extendable in a stacking direction of the plurality of the cells,

the circuit body having:

a band-shaped main strip to be located to extend in the stacking direction;

a band-shaped first branch strip branched from the main strip and extending toward a corresponding busbar among the plurality of the busbars; and

a second branch strip branched from the main strip and extending toward the external device,

the first branch strip having:

a bent portion extending in the stacking direction and having a bent shape around an axis crossing the stacking direction; and

a busbar connection portion disposed closer to an end of the first branch strip than the bent portion and connected to the corresponding busbar,

the second branch strip having

a device connection portion to be connected to the external device.

[2] The busbar module according to the item [1], wherein

at least a part of the second branch strip extends in the stacking direction and has a bent shape around the axis crossing the stacking direction.

[3] The busbar module according to the item [1] or the item [2], wherein

the second branch strip branches off the main strip from a side edge of the main strip or from inside area of the main strip.

[4] The busbar module according to any one of the item [1] to the item [3], wherein

the first branch strip extends from the main strip toward one side in the thickness direction of the main strip,

the second branch strip extends from the main strip toward the other side in the thickness direction of the main strip.

[5] The busbar module according to any one of the item [1] to the item [4], wherein

the device connection portion has a connector structure to be connected to a counterpart connector of the external device or a board connection structure to be connected to a circuit board of the external device.

According to first aspect of the invention, relating to the item [1], the circuit body which is a flexible circuit board is composed of the band-shaped main strip, the band-shaped busbar branch strips which branch off the main strip, and the device branch strip. Each of the busbar branch strips connected to the respective busbars includes the bent portion that is bent along the axis that crosses the stacking direction of the plurality of cells. With this configuration, when the battery assembly extends or contracts in its stacking direction due to thermal deformation of each cell, each busbar can move in the stacking direction of the cells because the bent portion of each busbar branch strip of the circuit body is bent or stretched. Likewise, dispersion of the size of the battery assembly in its stacking direction due to an assembling allowance of each cell can be absorbed by bending or stretching of the bent portions of the busbar branch strips of the circuit body. In other words, the busbar module having this configuration can easily accommodate expansion/contraction and manufacture dispersion of the battery assembly by deformation of substantially only the busbar branch strips with no deformation of the main strip of the circuit body.

Furthermore, the busbar module having this configuration can flexibly accommodate external devices having various structures or installed at various locations by determining, as appropriate, a position where the device branch strip to be connected to an external device (e.g., voltage detection device (not shown)) branches off the main strip according to an installation location of the external device or its structure (e.g., a position of a connector of the external device).

In general, even in the case where a flexible circuit board includes a number of circuit structures, it can be deformed flexibly by a much weaker force than the electric wires used in the above-described conventional busbar module. Thus, the ease of attachment of the circuit body to the battery assembly is increased remarkably.

As such, the busbar module having this configuration is higher in the ease of attachment to the battery assembly and the followability to deformation and manufacture dispersion of the battery assembly and is also higher in the degree of freedom of selection of an installation location and a structure of an external device than the above-described conventional busbar module.

According to second aspect of the invention, relating to the item [2], like each busbar branch strip connected to the associated busbar, the device branch strip to be connected to the external device has a shape obtained by being bent along an axis that crosses the stacking direction of the plurality of cells. Thus, the busbar module can flexibly accommodate external devices that are different from each other in installation location or structure. Furthermore, since the device branch strip is bent and stretched, work of connecting the device branch strip to the external device (e.g., work of fitting the connector provided at the end of the device branch strip to a connector of the external device) is made easier and hence work of connecting the busbar module to the external device can be increased in efficiency. Incidentally, as in the case of each busbar branch strip, even when the device branch strip is bent or stretched, substantially only the device branch strip is deformed with no deformation of the main strip of the circuit body.

According to third aspect of the invention, relating to the item [3], the device branch strip branches off the main strip from a side edge of the main strip or from inside the main strip and then extends toward the external device. This structure makes it possible to accommodate, more flexibly, external devices that are different from each other in installation location or structure. Where the device branch strip branches off the main strip from a side edge of the main strip, the device branch strip may be formed so as to, for example, either extend from the side edge in the width direction of the main strip or extend in the thickness direction of the main strip from an edge of a cut that is formed so as to have an opening in the side edge. Where the device branch strip branches off the main strip from inside the main strip, the device branch strip may be formed so as to, for example, extend in the thickness direction of the main strip from an edge of an opening formed inside the main strip.

According to fourth aspect of the invention, relating to the item [4], each of the busbar branch strips and the device branch strip extend in the thickness direction of the main strip toward the opposite sides. With this measure, the device branch strip can be prevented from interfering with the busbar branch strips by, for example, disposing the battery assembly under the busbar module and disposing the external device above the busbar module.

According to fifth aspect of the invention, relating to the item [5], the device connection portion of the device branch strip may have, for example, a connector structure that can be connected to a counterpart connector of the external device or a structure that can be connected directly to a circuit board of the external device. In this manner, the device branch strip can be connected to various kinds of external devices.

The invention can provide a busbar module that is high in the ease of attachment to a battery assembly and the followability to deformation and manufacture dispersion of the battery assembly and is also high in the degree of freedom of selection of an installation location and structure of an external device.

The invention has been described above concisely. The details of the invention will become more apparent when the modes for carrying out the invention (hereinafter referred to as an embodiment) described below are read through with reference to the accompanying drawings.

DETAILED DESCRIPTION

Embodiment

A busbar module10according to an embodiment of the present invention will be hereinafter described with reference to the drawings. The busbar module10according to the embodiment is used being attached to a battery assembly (i.e., a battery module in which plural cells are laid on each other) that is a drive power source installed in an electric vehicle, a hybrid vehicle, or the like.

(Configuration of Battery Assembly1)

First, a battery assembly1to which the busbar module10according to the embodiment is to be attached will be described. As shown inFIG. 2, the battery assembly1is configured in such a manner that plural cells2are connected to each other in series. A positive electrode4and a negative electrode5project from the top of a cuboid-shaped battery main body (main body)3of each of the plurality of cells2. The positive electrode4and the negative electrode5, which are shaped like a cylinder, are spaced from each other and project upward approximately in the vertical direction from an electrode surface6of the battery main body3.

The battery assembly1is configured by laying the cells2on each other in a preset direction (stacking direction) in such a manner that the positive electrodes4and the negative electrodes5of the cells2are arranged alternately. The positive electrode4of one of end cells2located at the two respective ends of the series connection of the cells2of the battery assembly1serves as an assembly positive electrode and the negative electrode5of the other end cell2serves as an assembly negative electrode.

Next, the busbar module10according to the embodiment will be described. As shown inFIG. 1, the busbar module10has a circuit body20which is a flexible circuit board (FPC) and to which busbars25(seeFIG. 3) to be connected to the positive electrodes4and the negative electrodes5of the cells2are attached and a holder (electrode routing body)30which houses and holds the circuit body20and attaches it to the battery assembly1.

As shown inFIGS. 1 and 3, the circuit body20has a band-shaped main strip21which is formed with plural wiring patterns and is to extend over the cells2in their stacking direction. In this example, a connector212is attached to an end portion of the main strip21via voltage detection lines211which lead out of the main strip21. The connector212can be connected to a voltage detection device (external device, not shown) that is provided outside the busbar module10.

Busbar branch strips201each of which consists of a first branch portion22and a second branch portion23are connected to side edges, extending parallel with the longitudinal direction (substantially coincident with the stacking direction of the battery assembly1) of the main strip21, of the main strip21. More specifically, band-shaped first branch portions22extending in the direction that crosses the longitudinal direction and the thickness direction of the main strip21(i.e., outward in the width direction of the main strip21) are connected to the side edges of the main strip21. Band-shaped second branch portions23extend from the tips of the first branch portions22, respectively, in parallel with the stacking direction of the battery main bodies3. The main strip21, the first branch portions22, and the second branch portions23are an FPC and hence can be deformed flexibly particularly in the direction that is perpendicular to their planes.

As shown inFIGS. 4 and 5A, each second branch portion23has a bent portion231which is bent along lines L1and L2that cross the stacking direction (in this example, substantially coincident with the extension direction of the second branch portion23) of the battery assembly1(that is, along axes extending parallel with the width direction of the second branch portion23). Having a first bent portion231A which is bent along the axis L1and a second bent portion231B which is bent along the axis L2, the second branch portion23is bent so as to assume an S shape (or an inverted S shape) as a whole. As such, the second branch portion23can move in the longitudinal direction of the main strip21(i.e., the stacking direction of the battery assembly1) and extend and contract in the top-bottom direction.

The first branch portions22are located outside the main strip21in the same plane as the main strip21, and the second branch portions23are connected to the respective first branch portions22. Thus, the second branch portions23are located outside the main strip21in its width direction and extend generally downward so as to assume an S shape in a state that there is no deviation between the battery assembly1and the circuit body20(seeFIG. 5A). Thus, the busbars25are located outside the main strip21in its width direction below the plane of the main strip21.

An end portion, opposite to the first branch portion22, of each second branch portion23is a tip portion232having a plane that is approximately parallel with the main strip21, and a connection portion24is attached to the top surface of the tip portion232. The bottom surface of the connection portion24is parallel with and at a different height as the bottom surface of the main strip21, and hence these bottom surfaces are spaced from each other. The top surface of the connection portion24is connected to a busbar25that connects a positive electrode4and a negative electrode5of adjacent cells2of the battery assembly1. Since the second branch portion23is thus connected to the electrodes4and5of those cells2via the connection portion24and the busbar25, the associated voltage detection line211is connected to the electrodes4and5.

As shown inFIGS. 3 and 5A, each busbar25is a plate-like conductive member (made of copper, for example) and has a busbar main body251which is rectangular as a whole and a connection piece252which projects from the busbar main body251to the side of the main strip21. Two electrode holes253into which a positive electrode4and a negative electrode5of adjacent cells2are to be inserted, respectively, penetrate through the busbar main body251. The side edge located on the side of the main strip21and the opposite side edge of the busbar main body251are formed with respective positioning recesses254at positions corresponding to the middle between the two electrode holes253. The connection portion24of the second branch portion23is connected to the bottom surface of the connection piece252of the busbar25.

Busbars25A that are located at the two respective ends of the main strip21in its longitudinal direction are connected to the assembly positive electrode or the assembly negative electrode and are each formed with one electrode hole253through which the assembly positive electrode or the assembly negative electrode is to be inserted. Power cables (not shown) for extracting power from the battery assembly1are connected to the respective busbars25A.

As shown inFIG. 6, the holder30is made of a resin, for example, and has, at the center in the width direction, a main strip housing portion31which extends in the stacking direction of the cells2and houses and holds the main strip21of the circuit body20. The main strip housing portion31is provided with main strip support members311which are arranged at preset intervals in the longitudinal direction of the main strip21to be housed. The main strip21is put on the main strip support members311. The main strip support members311may be omitted if the main strip21, the first branch portions22, and the second branch portions23are strong enough to allow the circuit body20of this example to be self-supported even if it is not supported by the main strip support members311. The main strip support members311may be provided even in such a case to exercise an auxiliary support function even in a case that the circuit body20cannot be self-supported for a certain reason. That is, the circuit body20may be either put on and supported by the main strip support members311or self-supported without the main strip support members311.

Two busbar housing portions32for housing the busbars25are provided outside the main strip housing portion31in the width direction. Each busbar housing portion32is provided with plural housing spaces33which are to house respective busbars25and are arranged in the stacking direction of the cells2. As also shown inFIG. 7, adjacent housing spaces33are bounded by a partition wall34, whereby the busbars25housed there are prevented from coming into contact with each other. Housing spaces33A for housing the busbars25A to which the power cables (not shown) are connected, respectively, are provided adjacent to the two respective ends of the main strip21in its longitudinal direction, and power cable housing portions36are provided so as to be continuous with the respective housing spaces33A.

As shown inFIG. 7, each housing space33, which is a rectangular space that is open at the top, is bounded by an outer wall331located outside in the width direction, an inner wall332located inside in the width direction, and a pair of partition walls34located on the two respective ends in the stacking direction. The partition wall34located on one side in the stacking direction (the left-side partition wall34inFIG. 7) is connected to the outer wall331and the inner wall332via respective extendable/contractable portions35. Thus, each housing space33can extend and contract in the stacking direction.

Bottom end portions of the outer wall331and the inner wall332are connected to each other by a connection plate333. The bottom end portions of the outer wall331and the inner wall332are formed with lock nails334inside, whereby a busbar25can be held between the connection plate333and the lock nails334. Projections338project inward from the inner side surfaces of the outer wall331and the inner wall332at the centers in the stacking direction, respectively. The projections338serve to position the associated busbar25by fitting into the respective positioning recesses254(seeFIG. 5A) of the busbar25.

The inner wall332is formed with a cut336and a support plate337projects inward at a position corresponding to the cut336. As a result, the connection piece255of the busbar25housed in the housing space33is supported by the support plate337.

The connection plate333is formed with spaces335on the two respective sides of the center in the stacking direction. Thus, the positive electrode4and the negative electrode5of the cells2can be exposed in the housing space33through the respective spaces335and can be connected to the electrode holes253of the busbar25housed in the housing space33. A bottom plate may be provided in place of the connection plate333so as to be formed with cuts or holes corresponding to the positive electrode4and the negative electrode5of the cells2, respectively.

As shown inFIG. 1, the holder30houses and holds a portion of the circuit body20, the portion being located in the rear of a position that is located in the rear of the front end, to which the connector212is connected, of the main strip21by a preset length (i.e., the portion in a range including at least positions where the first branch portions22branch off the main strip21). In other words, a portion (hereinafter referred to as an “exposed portion213”), having the preset length from the front end, to which the connector212is connected, of the main strip21is not housed in the holder30and is exposed from the holder30.

Next, a description will be made of how the busbar module10operates.FIG. 5Ashows a state that the second branch portion23is bent so as to assume an S shape as a whole,FIG. 5Bshows a state that the second branch portion23is stretched rearward a little, andFIG. 5Cshows a state that the second branch portion23is stretched forward.

As described above, the main strip21is put on the main strip support members311of the holder30and hence can move upward and in the longitudinal direction. Although the busbars25are housed in the respective housing spaces33, the housing spaces33can move in the longitudinal direction of the main strip21. The main strip21is connected to the busbars25via the respective second branch portion23which are bent in an S shape (seeFIG. 5A).

Even if, for example, the battery assembly1is deformed in this state and the relative positional relationship between the battery assembly1and the circuit body20is changed and the relative positional relationships between the main strip21and the busbars25are thereby changed, the changes (deviations) in the relative positional relationships can be absorbed by bending or stretching of the second branch portions23. Likewise, even if the size of the battery assembly1in its stacking direction varies from one battery assembly1manufactured to another due to an assembling allowance of the plurality of cells2, that manufacture dispersion can be absorbed by bending or stretching of the second branch portions23.

This will be described below more specifically.FIG. 5Bshows a case that the busbar25has deviated a little rearward (rightward inFIG. 5B) with respect to the main strip21. In this case, the S shape of the bent portion231of the second branch portion23is deformed to absorb the deviation of the busbar25.FIG. 5Cshows a case that the busbar25has deviated greatly forward (leftward inFIG. 5C) with respect to the main strip21. In this case, the S shape of the bent portion231of the second branch portion23is stretched to absorb the deviation of the busbar25. Although not shown in any drawings, when the main strip21is moved upward or downward and its relative positional relationships with the busbars25are thereby changed, the S shape of each bent portion231is stretched in the top-bottom direction to absorb that changes in the relative positional relationships.

In the above-described embodiment, the bent portion231of each second branch portion23is bent so as to assume an S shape (or inverted S shape) as a whole. Alternatively, as shown inFIG. 8A, each bent portion231may be bent so as to assume a Z shape (or an inverted Z shape) as a whole. As another alternative, as shown inFIG. 8B, each bent portion231may be bent so as to assume a C shape (or an inverted C shape) as a whole. As a further alternative, as shown inFIG. 8C, each bent portion231may be formed so as to assume an O shape. As in the example shown inFIG. 8C, if necessary, the branch portions22and23may be formed so that the bottom surfaces of the main strip21and each connection portion24are in the same plane.

Although in the above embodiment each first branch portion22is in the same plane as the main strip21, as shown inFIG. 9Aeach first branch portion22may extend in such a direction as to cross the bottom surface of the main strip21(e.g., inFIG. 9Athe first branch portion22extends perpendicularly to the main strip21, more specifically, downward). Although in the above-described embodiment each first branch portion22branches off the main strip21from its side edge, another alternative is possible in which as shown inFIG. 9Bopenings29are formed inside the main strip21and each first branch portion22branches off the main strip21from an edge of the associated opening29.

(Modifications of Connection Between Circuit Body20and External Device)

In the embodiment, as described above with reference toFIG. 1, the connector212is connected to the voltage detection lines211that are led out so as to be connected to the end portion of the main strip21. The circuit body20is connected to the voltage detection device using the connector212.

In the following, modifications of the connection between the circuit body20and the voltage detection device (external device) will be described with reference toFIG. 10andFIGS. 11A and 11B.

As shown inFIG. 10, in one modification, each busbar branch strip201(first branch portion22and second branch portion23) branches off the main strip21from its one side edge21A and extends downward and a device branch strip401branches off the main strip21from its other side edge21B and extends upward. Like each busbar branch strip201described above, the device branch strip401has a band-shaped first branch portion42which extends in a direction that crosses the longitudinal direction and the thickness direction of the main strip21(i.e., outward in the width direction of the main strip21). A band-shaped second branch portion43extends from the tip of the first branch portion42in a direction that is parallel with the stacking direction of the battery main bodies3. A terminal portion of the second branch portion43is provided with a connector51. The connector51is connected to a connector (not shown) of a voltage detection device (not shown) that is installed above the busbar module10.

The main strip21, the first branch portion42, and the second branch portion43are an FPC. Thus, as in the case shown inFIGS. 5A-5C, the main strip21and the device branch strip401can be deformed flexibly particularly in the direction that is perpendicular to their planes.

More specifically, like the second branch portion23of each busbar branch strip201, the second branch portion43of the device branch strip401is bent in an S shape (or an inverted S shape) as a whole. Thus, the second branch portion43can move in the longitudinal direction of the main strip21(i.e., the stacking direction of the battery assembly1) and extend and contract in the top-bottom direction. Furthermore, the first branch portion42of the device branch strip401is disposed outside the main strip21in the same plane and the second branch portion43is connected to the first branch portion42. Thus, the second branch portion43is located outside the main strip21in its width direction and assumes an S shape (erected upward) in a state that the relative positional relationship between the voltage detection device and the circuit body20is not varied.

(Modifications of Device Branch Strip401)

In the example shown inFIG. 10, the device branch strip401extends from the side edge21B of the main strip21. Alternatively, as shown inFIG. 11A, a device branch strip401may be configured so as to extend in the thickness direction of the main strip21from an edge of a cut21C that is formed so as to have an opening in the side edge21B. As another alternative, as shown inFIG. 11B, a device branch strip401may be configured so as to extend in the thickness direction of the main strip21from an edge of an opening21D that is formed inside the main strip21at a position distant from the side edge21B.

The position of the device branch strip401may be determined as appropriate taking the positional relationship between the busbar module10and the voltage detection device and other factors into consideration.

Main Advantages of Embodiment

As described above, in the busbar module10according to the embodiment, the circuit body20which is a flexible circuit board (FPC) is composed of the band-shaped main strip21, the band-shaped busbar branch strips201which branch off the main strip21, and the device branch strip401. Each of the busbar branch strips201connected to the respective busbars25includes the bent portion231which is bent along axes that cross the stacking direction of the plurality of cells2. With this configuration, when the battery assembly1extends or contracts in its stacking direction due to thermal deformation of each cell2, each busbar25can move in the stacking direction of the cells2because the bent portion231of each busbar branch strip201of the circuit body20is bent or stretched. Likewise, dispersion of the size of the battery assembly1in its stacking direction due to an assembling allowance of each cell2can be absorbed by bending or stretching of the bent portions231of the busbar branch strips201of the circuit body20. In other words, the busbar module10having this configuration can easily accommodate expansion/contraction and manufacture dispersion of the battery assembly1by deformation of substantially only the busbar branch strips201with no deformation of the main strip21of the circuit body20.

Furthermore, the busbar module10having this configuration can flexibly accommodate external devices having various structures or installed at various locations by determining, as appropriate, a position where the device branch strip401to be connected to an external device (e.g., voltage detection device (not shown)) branches off the main strip21according to an installation location of the external device or its structure (e.g., a position of a connector of the external device).

In general, even in the case where a flexible circuit board includes a number of circuit structures, it can be deformed flexibly by a much weaker force than the electric wires used in the above-described conventional busbar module. Thus, the ease of attachment of the circuit body20to the battery assembly1is increased remarkably.

As such, the busbar module10having this configuration is higher in the ease of attachment to the battery assembly1and the followability to deformation and manufacture dispersion of the battery assembly1and is also higher in the degree of freedom of selection of an installation location and a structure of an external device than the above-described conventional busbar module.

Like each busbar branch strip201connected to the associated busbar25, the device branch strip401to be connected to the external device has a shape obtained by being bent along an axis that crosses the stacking direction of the plurality of cells2. Thus, the busbar module10can flexibly accommodate external devices that are different from each other in installation location or structure. Furthermore, since the device branch strip401is bent and stretched, work of connecting the device branch strip401to the external device (e.g., work of fitting the connector51provided at the end of the device branch strip401to a connector of the external device) is made easier and hence work of connecting the busbar module10to the external device can be increased in efficiency. Incidentally, as in the case of each busbar branch strip201, even when the device branch strip401is bent or stretched, substantially only the device branch strip401is deformed with no deformation of the main strip21of the circuit body20.

The device branch strip401branches off the main strip21from a side edge of the main strip21or from inside the main strip21and then extends toward the external device. This structure makes it possible to accommodate, more flexibly, external devices that are different from each other in installation location or structure. Where the device branch strip401branches off the main strip21from a side edge of the main strip21, the device branch strip401may be formed so as to, for example, either extend from the side edge in the width direction of the main strip21or extend in the thickness direction of the main strip21from an edge of a cut that is formed so as to have an opening in the side edge. Where the device branch strip401branches off the main strip21from inside the main strip21, the device branch strip401may be formed so as to, for example, extend in the thickness direction of the main strip21from an edge of an opening formed inside the main strip21.

Each of the busbar branch strips201and the device branch strip401extend in the thickness direction of the main strip21toward the opposite sides. With this measure, the device branch strip401can be prevented from interfering with the busbar branch strips201by, for example, disposing the battery assembly1under the busbar module10and disposing the external device above the busbar module10.

Furthermore, the device branch strip401has the connector51as a device connection portion that can be connected to a counterpart connector of the external device. The device branch strip401may have, for example, a structure that can be connected directly to a circuit board of the external device, instead of the connector51. In this manner, the device branch strip401can be connected to various kinds of external devices.

Other Embodiments

The invention is not limited to the above embodiment and various modifications, improvements, etc. can be made as appropriate within the scope of the invention. The materials, shapes, sets of dimensions, numbers, locations, etc. of the respective constituent elements of the above embodiment are not limited to those disclosed but can be determined in desired manners as long as the invention can be implemented.

Features of the above-described busbar module10according to the embodiment of the invention will be summarized below concisely in the form of items [1] to [5]:

[1] A busbar module (10) to be attached to a battery assembly (1) having a stack of a plurality of cells (2) and to connect the plurality of the cells (2) to an external device, the busbar module (10) comprising:

a circuit body (20) having a flexible circuit board including a wiring pattern; a plurality of busbars (25) to be connected to corresponding electrodes of the plurality of the cells (2); and a holder (30) holding the busbars (25) and being extendable in a stacking direction of the plurality of the cells (2),

the circuit body (20) having:

a band-shaped main strip (21) to be located to extend in the stacking direction;

a band-shaped first branch strip (201) branched from the main strip (21) and extending toward a corresponding busbar among the plurality of the busbars (25); and

a second branch strip (401) branched from the main strip (21) and extending toward the external device,

the first branch strip (201) having:

a bent portion (231) extending in the stacking direction and having a bent shape around an axis crossing the stacking direction; and

a busbar connection portion (24) disposed closer to an end of the first branch strip (201) than the bent portion (231) and connected to the corresponding busbar,

the second branch strip (401) having

a device connection portion (51) to be connected to the external device.

[2] The busbar module (10) according to the item [1], wherein

at least a part of the second branch strip (401) extends in the stacking direction and has a bent shape around the axis crossing the stacking direction.

[3] The busbar module (10) according to the item [1] or the item [2], wherein

the second branch strip (401) branches off the main strip (21) from a side edge of the main strip (21) or from inside area of the main strip (21).

[4] The busbar module (10) according to any one of the item [1] to the item [3], wherein

the first branch strip (201) extends from the main strip (21) toward one side in the thickness direction of the main strip (21),

the second branch strip (401) extends from the main strip (21) toward the other side in the thickness direction of the main strip (21).

[5] The busbar module (10) according to any one of the item [1] to the item [4], wherein

the device connection portion (51) has a connector structure to be connected to a counterpart connector of the external device or a board connection structure to be connected to a circuit board of the external device.

REFERENCE SIGNS LIST