Patent ID: 12249736

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a busbar module according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by the embodiment. In addition, constituent elements in the following embodiment include those that can be easily assumed by those skilled in the art or those that are substantially the same.

Embodiment

An embodiment will be described with reference toFIGS.1to21. The present embodiment relates to a busbar module.FIG.1is a perspective view of a busbar module and a battery module according to the embodiment,FIG.2is an exploded perspective view of the busbar module according to the embodiment,FIG.3is a plan view of a circuit body and a busbar according to the embodiment,FIG.4is a perspective view of the busbar according to the embodiment,FIG.5is a perspective view illustrating a main part of the circuit body according to the embodiment,FIG.6is a plan view of a case according to the embodiment,FIG.7is a perspective view of the case according to the embodiment,FIG.8is a perspective view of a cover according to the embodiment, andFIG.9is a view for describing an internal configuration of the circuit body according to the embodiment.

FIG.10is a cross-sectional view of a thick portion of the circuit body according to the embodiment,FIG.11is a cross-sectional view of a thin portion of the circuit body according to the embodiment,FIG.12is a cross-sectional view of the circuit body according to the embodiment,FIG.13is a perspective view of the circuit body according to the embodiment,FIG.14is a perspective view of the case according to the embodiment,FIG.15is a cross-sectional view of the case according to the embodiment,FIG.16is a side view of the case and the circuit body according to the embodiment,FIG.17is a cross-sectional view of the case and the circuit body according to the embodiment,FIG.18is a cross-sectional view of the busbar module according to the embodiment,FIGS.19and20are cross-sectional views of the circuit body and the busbar according to the embodiment, andFIG.21is a perspective view of the busbar according to the embodiment.FIG.12illustrates a cross section taken along line XII-XII inFIG.3.FIG.15illustrates a cross section taken along line XV-XV inFIG.6.FIG.17illustrates a cross section taken along line XVII-XVII inFIG.1.FIG.18illustrates a cross section taken along line XVIII-XVIII inFIG.1.FIG.19illustrates a cross section taken along line XIX-XIX inFIG.3.FIG.20illustrates a cross section taken along line XX-XX inFIG.19.

As illustrated inFIG.1, a battery pack100of the present embodiment includes a busbar module1and a battery module110. The battery pack100is mounted as a power source on a vehicle such as an electric vehicle (EV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV). The battery pack100may include a plurality of busbar modules1and a plurality of battery modules110.

The battery module110includes a plurality of battery cells120. The illustrated shape of the battery cell120is a rectangular parallelepiped shape. Two electrodes121are disposed on a first surface120aof the battery cell120. The first surface120ahas a substantially rectangular shape.

The plurality of battery cells120are arranged in a first direction X. More specifically, the plurality of battery cells120are arranged in such a manner that a longer side of the first surface120afaces a longer side of another adjacent first surface120ain the first direction X. In the following description, a direction orthogonal to the first direction X on the first surface120ais referred to as a “second direction Y”. The second direction Y is a longitudinal direction of the first surface120a. A direction orthogonal to both the first direction X and the second direction Y is referred to as a “third direction Z”. The third direction Z is a height direction of the battery cell120. The first surface120ais orthogonal to the third direction Z. For example, the battery pack100is mounted on the vehicle in such a manner that the first surface120afaces upward in a top-bottom direction of the vehicle.

The two electrodes121on the first surface120aare arranged in the second direction Y. One of the two electrodes121on the first surface120ais a positive electrode, and the other is a negative electrode. An aggregate of the electrodes121arranged at one ends of the first surfaces120ain the longitudinal direction is referred to as a “first electrode group121a”. An aggregate of the electrodes121arranged at the other ends of the first surfaces120ain the longitudinal direction is referred to as a “second electrode group121b”. In the battery module110of the present embodiment, the positive electrodes and the negative electrodes are alternately arranged in the first electrode group121a. In the second electrode group121b, the positive electrodes and the negative electrodes are alternately arranged. The busbar module1of the present embodiment connects the plurality of battery cells120in series.

The busbar module1includes a plurality of busbars2, a plate-like circuit body3, a case4, and a cover5. The busbar2is formed of a conductive metal plate such as copper or aluminum. As illustrated inFIGS.2and3, the busbar module1includes a first busbar group2A and a second busbar group2B. The first busbar group2A and the second busbar group2B include the plurality of busbars2arranged in the first direction X. The busbars2of the first busbar group2A are fixed to the first electrode group121aof the battery module110. The busbars2of the second busbar group2B are fixed to the second electrode group121b.

As illustrated inFIG.4, the busbar2includes a main body20and a terminal21. The main body20and the terminal21are electrically connected by welding or the like, for example. The main body20electrically connects two electrodes121adjacent to each other in the first direction X. The main body20includes a base portion20a, a first connecting portion20b, and a second connecting portion20c. The base portion20ahas a rectangular flat plate shape and is orthogonal to the third direction Z.

The first connecting portion20band the second connecting portion20care arranged with a gap in the first direction X and protrude from the base portion20ain the second direction Y. The first connecting portion20band the second connecting portion20care orthogonal to the third direction Z. The first connecting portion20bis connected to one electrode121of two adjacent electrodes121. The second connecting portion20cis connected to the other electrode121of the two adjacent electrodes121. Each of the first connecting portion20band the second connecting portion20cmay be connected to the electrode121by welding, may be connected to the electrode121by a fastening member, or may be connected to the electrode121by other means.

The terminal21has a flat plate shape and is fixed to the base portion20aof the main body20. The terminal21protrudes with respect to the base portion20atoward a side opposite from a side of the first connecting portion20band the second connecting portion20c. The terminal21has a first surface21aand a second surface21b. The first surface21ais one of two main surfaces of the terminal21, and faces the base portion20ain the third direction Z. The second surface21bis the other of the two main surfaces of the terminal21.

A through-hole21cpenetrating through the terminal21in a thickness direction is formed in the terminal21. The through-hole21cis disposed at a distal end portion of the terminal21. The through-hole21cis opened in each of the first surface21aand the second surface21b.

The circuit body3is a plate-like circuit body and has flexibility. The circuit body3of the present embodiment is a flexible printed circuit (FPC). The circuit body3includes a plurality of connection conductors6corresponding to the plurality of busbars2. As illustrated inFIGS.2and3, the circuit body3includes a trunk portion30and a plurality of branch portions31. The trunk portion30and the branch portion31are integrally formed.

The trunk portion30has a flat plate shape and extends along the first direction X. As illustrated inFIG.3, the trunk portion30has a first side30aand a second side30bextending along the first direction X. The first side30ais an edge of one end of the trunk portion30in the second direction Y. The second side30bis an edge of the other end of the trunk portion30in the second direction Y. The branch portion31branches from the trunk portion30. The illustrated circuit body3includes the plurality of branch portions31branching from the first side30aand the plurality of branch portions31branching from the second side30b. The branch portion31connected to the first side30ais connected to the busbar2of the first busbar group2A. The branch portion31connected to the second side30bis connected to the busbar2of the second busbar group2B.

The trunk portion30has a first end portion30cand a second end portion30d. The first end portion30cis one end portion of the trunk portion30in the first direction X. The second end portion30dis the other end portion of the trunk portion30in the first direction X. A connector3cis connected to the first end portion30c. The trunk portion30is connected to a monitoring device that monitors a state of the battery module110via the connector3c. The monitoring device monitors, for example, a voltage and temperature of the battery cell120.

A first through-hole30eis provided in the first end portion30c. A second through-hole30fand a third through-hole30gare provided in the second end portion30d. The first through-hole30e, the second through-hole30f, and the third through-hole30gpenetrate through the trunk portion30in the third direction Z. The first through-hole30e, the second through-hole30f, and the third through-hole30gare disposed, for example, at the center of the trunk portion30in the second direction Y. The illustrated shape of the first through-hole30eis a circular shape having a uniform diameter. The illustrated shapes of the second through-hole30fand the third through-hole30gare oval shapes along the first direction X. In the first direction X, a length of the third through-hole30gis larger than a length of the second through-hole30f.

As illustrated inFIG.5, the branch portion31includes a base portion32, an intermediate portion33, and a fixed portion34. The base portion32protrudes from the trunk portion30toward the second direction Y. The fixed portion34is a portion fixed to the busbar2and is positioned at a distal end portion of the branch portion31. The intermediate portion33extends along the first direction X from the base portion32toward the fixed portion34.

The circuit body3includes a plurality of connection conductors6. The connection conductor6of the present embodiment is a conductive metal foil, for example, a copper foil. The connection conductor6has a first portion61routed in the trunk portion30and a second portion62routed in the branch portion31. An end portion of the first portion61is connected to the connector3c. A proximal end of the second portion62is connected to the first portion61. A distal end of the second portion62is connected to a chip fuse3f.

The chip fuse3fis disposed in the fixed portion34. The chip fuse3fis interposed between the second portion62and a pad35. The chip fuse3fis configured to cut between the pad35and the connection conductor6when an excessive current flows between the pad35and the connection conductor6. The pad35is a metal foil formed on the fixed portion34, and is exposed to an external space. The busbar2is soldered to the pad35. The pad35includes a first pad35aand a second pad35b. The first pad35aand the second pad35bface each other in the second direction Y with the chip fuse3finterposed therebetween. The first pad35aand the second pad35bare electrically connected to each other.

The circuit body3of the present embodiment is connected to the busbar2in a state where the intermediate portion33of the branch portion31is curved. Tolerances in position, height, and the like of the battery cell120are absorbed by the branch portion31of the circuit body3. As described later, the branch portion31of the present embodiment has a thin portion3bhaving a small thickness. The branch portion31connects the trunk portion30and the busbar2in a state where the thin portion3bis curved. The branch portion31having the thin portion3bhas flexibility and high followability. Therefore, the busbar module1of the present embodiment can improve workability of attachment work with respect to the battery module110. In addition, the busbar module1of the present embodiment can reduce a reaction force generated in the curved portion to suppress floating or the like of the circuit body3.

As illustrated inFIG.6, the case4includes a plurality of busbar accommodating portions40, a plurality of bridge portions41, and a plurality of coupling portions42. The case4is molded using, for example, an insulating synthetic resin. The busbar accommodating portion40, the bridge portion41, and the coupling portion42are integrally formed. The case4has a rectangular shape elongated in the first direction X.

The busbar accommodating portion40is a portion that accommodates the busbar2and has a tubular shape in the third direction Z. One busbar accommodating portion40accommodates one busbar2. The plurality of busbar accommodating portions40are arranged in the first direction X. The case4has a first side4aand a second side4bextending along the first direction X. The first side4ais an edge of one end of the case4in the second direction Y. The second side4bis an edge of the other end of the case4in the second direction Y.

The case4includes the plurality of busbar accommodating portions40arranged on the first side4aand the plurality of busbar accommodating portions40arranged on the second side4b. The busbar accommodating portion40on the first side4aaccommodates the busbar2of the first busbar group2A. The busbar accommodating portion40on the second side4baccommodates the busbar2of the second busbar group2B. The busbar accommodating portion40has a partition wall44. The partition wall44partitions between the first connecting portion20band the second connecting portion20cof the busbar2. The busbar accommodating portion40has a facing surface45connected to the partition wall44. The facing surface45faces the base portion20aand the terminal21of the busbar2in the third direction Z.

The bridge portion41connects one busbar accommodating portion40arranged on the first side4aand one busbar accommodating portion40arranged on the second side4b. The plurality of bridge portions41are arranged in the first direction X. The bridge portion41functions as a support that supports the trunk portion30of the circuit body3. The bridge portion41extends in the second direction Y from the partition wall44on the first side4ato the partition wall44on the second side4b. The case4includes a first bridge portion41A and a second bridge portion41B. The first bridge portion41A and the second bridge portion41B are bridge portions41positioned at end portions in the first direction X among the plurality of bridge portions41. The first bridge portion41A supports the first end portion30cof the circuit body3. The second bridge portion41B supports the second end portion30dof the circuit body3.

The coupling portion42is a portion that connects two adjacent busbar accommodating portions40. As illustrated inFIG.7, the coupling portion42has an arch shape. The coupling portion42has flexibility and allows relative movement of two adjacent busbar accommodating portions40. More specifically, the coupling portion42is formed to allow the relative movement of the busbar accommodating portions40in at least the first direction X. The coupling portion42may allow the relative movement of the busbar accommodating portions40in the second direction Y and the third direction Z.

The case4includes a plurality of engaging pieces43. The engaging piece43is disposed more inwards than the partition wall44in the second direction Y. The illustrated engaging piece43is provided at an end portion of the bridge portion41. The engaging piece43protrudes in an arm shape in the third direction Z. A claw portion43ais formed at a distal end portion of the engaging piece43. The claw portion43aprotrudes in the second direction Y.

As illustrated inFIG.6, the case4includes a first protrusion46and a third protrusion47. The first protrusion46is a protrusion corresponding to the first through-hole30eof the circuit body3. The first protrusion46protrudes from the first bridge portion41A in the third direction Z. The third protrusion47is a protrusion corresponding to the third through-hole30gof the circuit body3. The third protrusion47protrudes from the second bridge portion41B in the third direction Z.

The cover5is a member that covers the circuit body3to protect the circuit body3. The cover5is engaged with the case4and forms a space for accommodating the trunk portion30between the case4and the cover5. The cover5is formed of, for example, an insulating synthetic resin. As illustrated inFIG.8, the cover5includes a cover main body50, an engaging portion51, and a second protrusion53. The cover main body50, the engaging portion51, and the second protrusion53are integrally formed.

The cover main body50has a substantially rectangular flat plate shape. The cover main body50has a first side50aand a second side50bextending along the first direction X. The first side50ais an edge of one end of the cover main body50in the second direction Y. The second side50bis an edge of the other end of the cover main body50in the second direction Y. As illustrated inFIG.2, a plurality of reinforcing ribs54are provided on an outer surface50dof the cover main body50. The ribs54extend in the first direction X and the second direction Y.

As illustrated inFIGS.2and8, the cover5includes a plurality of engaging portions51. The engaging portion51engages with the engaging piece43of the case4to couple the cover5to the case4. The engaging portions51are disposed on the first side50aand the second side50b. As illustrated inFIG.8, the engaging portion51has a rectangular tube shape having an engaging hole52. The engaging piece43of the case4is inserted into the engaging hole52in such a manner that the claw portion43aprotrudes from the engaging hole52. The claw portion43aof the engaging piece43is locked to the engaging portion51to couple the case4and the cover5with each other.

A length of the engaging hole52in the first direction X is sufficiently larger than a width of the engaging piece43. Therefore, the engaging portion51allows the engaging piece43to relatively move in the first direction X with respect to the engaging portion51. That is, the cover5allows the case4to expand and contract in the first direction X in a coupled state in which the cover5and the case4are coupled. The expansion and contraction of the case4is mainly caused by elastic deformation of the coupling portion42. That is, the cover5allows two adjacent busbar accommodating portions40to relatively move in the first direction X in the coupled state.

The second protrusion53protrudes from an inner surface50cof the cover main body50. The second protrusion53is a protrusion corresponding to the second through-hole30fof the circuit body3. The illustrated shape of the second protrusion53is a columnar shape.

Details of the circuit body3will be described.FIG.9is a diagram for describing an internal configuration of the circuit body3.FIG.9illustrates the branch portion31before being attached to the busbar2and the battery module110. InFIG.9, the connection conductor6is drawn by a solid line, but in the actual circuit body3, the connection conductor6is covered with coating layers11and12to be described later and is thus not exposed.

The circuit body3of the present embodiment has a thick portion3aillustrated inFIG.10and the thin portion3billustrated inFIG.11. The thick portion3ahas a five-layer structure. On the other hand, the thin portion3bhas a three-layer structure. In the circuit body3, at least the trunk portion30is composed of the thick portion3a. Since conductor layers13and14are disposed on both surfaces of a base layer10, respectively, both downsizing of the trunk portion30and routing of a large number of voltage detection circuits due to the multilayer structure are achieved. The thin portion3bis provided at the intermediate portion33of the branch portion31. The branch portion31connects the trunk portion30and the busbar2in a state where the thin portion3bis flexurally deformed. Since the thin portion3bhaving high flexibility is provided at the intermediate portion33, workability of work of attaching the busbar2to the battery module110is improved.

As illustrated inFIG.10, the thick portion3ahas a five-layer structure including a first circuit layer7A and a second circuit layer7B. The thick portion3aincludes the base layer10, the first coating layer11, the second coating layer12, the first conductor layer13, and the second conductor layer14. The base layer10, the first coating layer11, and the second coating layer12are all formed of an insulating synthetic resin. The base layer10, the first coating layer11, and the second coating layer12are formed of, for example, a polyimide resin. Both the base layer10and the coating layers11and12are formed to have flexibility.

The first coating layer11is a layer that covers a first surface10aof the base layer10. The second coating layer12is a layer that covers a second surface10bof the base layer10. The first conductor layer13is a conductor layer disposed between the first surface10aand the first coating layer11, and has flexibility. The illustrated first conductor layer13is a metal foil formed on the first surface10a. The first conductor layer13is typically the connection conductor6. A part of the first conductor layer13may be a reinforcing layer36as described later. The connection conductor6and the reinforcing layer36are formed by etching the metal foil formed on the first surface10a. After a circuit pattern or the like of the connection conductor6is formed on the first surface10a, the first coating layer11is bonded to the first surface10aand the first conductor layer13.

The illustrated second conductor layer14is a metal foil formed on the second surface10band has flexibility. The second conductor layer14is typically the connection conductor6. A part of the second conductor layer14may be the reinforcing layer36. The connection conductor6and the reinforcing layer36are formed by etching the metal foil formed on the second surface10b. After a circuit pattern or the like of the connection conductor6is formed on the second surface10b, the second coating layer12is bonded to the second surface10band the second conductor layer14.

FIG.11illustrates the thin portion3bcomposed of the first circuit layer7A. The illustrated thin portion3bhas a three-layer structure including the base layer10, the first coating layer11, and the first conductor layer13. In this case, no metal foil is formed on the second surface10bof the base layer10, or the metal foil on the second surface10bis removed by etching. Since the thin portion3bis thinner than the thick portion3a, the thin portion3bhas lower rigidity than that of the thick portion3aand has flexibility. The thin portion3bmay be composed of the second circuit layer7B.

As illustrated inFIG.9, the thin portion3bis provided at the intermediate portion33of the branch portion31. More specifically, substantially the entire intermediate portion33is the thin portion3b. Therefore, the illustrated branch portion31can connect the trunk portion30and the busbar2in a state where the entire intermediate portion33is flexurally deformed. A shape of the thin portion3bin plan view is substantially rectangular. More specifically, the illustrated thin portion3bhas a shape in which a rectangular end portion is curved outward. In the branch portion31, a portion excluding the thin portion3bis composed of the thick portion3a. That is, in the circuit body3, the trunk portion30, the base portion32, and the fixed portion34are composed of the thick portion3a.

As illustrated inFIG.9, the circuit body3of the present embodiment includes the reinforcing layer36. The reinforcing layer36is a metal foil that improves rigidity of a portion adjacent to the thin portion3b. The reinforcing layer36and the connection conductor6are separated from each other by etching the same copper foil, for example. Note that the reinforcing layer36may be a metal foil thicker than the connection conductor6. For example, the reinforcing layer36is disposed on a back side of the corresponding connection conductor6. For example, in a case where the connection conductor6of the branch portion31illustrated inFIG.9is disposed on the first surface10aof the base layer10, the reinforcing layer36is disposed on the second surface10b. A width of the reinforcing layer36is larger than a width of the connection conductor6.

The reinforcing layer36includes a first reinforcing layer36aand a second reinforcing layer36b. The first reinforcing layer36ais disposed at the trunk portion30and the base portion32. The second reinforcing layer36bis disposed at the fixed portion34. The first reinforcing layer36ahas a first portion36cdisposed at the trunk portion30and a second portion36ddisposed at the base portion32. The first portion36cand the second portion36dare integrated with each other.

The first portion36cextends from a connecting portion37that connects the trunk portion30and the branch portion31toward both sides in the first direction X. A shape of the first portion36cin plan view is substantially rectangular. A width of the first portion36cis the largest at the connecting portion37.

The second portion36dis provided in substantially the entire region of the base portion32. That is, the second portion36dextends from the connecting portion37to a distal end of the base portion32in the second direction Y. A width of the second portion36dis slightly smaller than a width of the base portion32.

The first reinforcing layer36aimproves rigidity of the connecting portion37and suppresses bending and twisting of the connecting portion37. In addition, the first reinforcing layer36aimproves rigidity of the base portion32and suppresses bending and twisting of the base portion32. Therefore, the first reinforcing layer36aenables flexural deformation of the intermediate portion33into a desired shape while suppressing deformation of the base portion32and the connecting portion37.

The second reinforcing layer36bis provided in substantially the entire region of the fixed portion34. The illustrated second reinforcing layer36bfaces each of the second portion62of the connection conductor6, the first pad35a, and the second pad35b. The second reinforcing layer36bimproves rigidity of the fixed portion34and suppresses bending and twisting of the fixed portion34. Therefore, the second reinforcing layer36bcan improve reliability of electrical performance in the fixed portion34.

As illustrated inFIG.12, a thickness t2of the thin portion3bis smaller than a thickness t1of the thick portion3a. The thin portion3bis provided from one end to the other end of the intermediate portion33. Therefore, the branch portion31can connect the trunk portion30and the busbar2while flexurally deforming the intermediate portion33into a desired curved shape. The illustrated curved shape of the intermediate portion33is an S-shape. The intermediate portion33is bent so as to have a first curved portion33aand a second curved portion33b. The first curved portion33ais curved toward one side in the first direction X. The second curved portion33bis curved toward the other side in the first direction X. The intermediate portion33curved in the S-shape can appropriately absorb tolerances in the first direction X, the second direction Y, and the third direction Z.

In addition, since the thickness t2of the intermediate portion33is small, a reaction force generated in the intermediate portion33is reduced. For example, the reaction force generated in the intermediate portion33is smaller than that in a case where the intermediate portion33is composed of the thick portion3a. Therefore, the busbar module1of the present embodiment can improve workability of work of fixing the busbar2to the battery cell120. In addition, the busbar module1can suppress floating and deformation of the circuit body3after the busbar2is fixed to the battery cell120.

Note that the branch portion31of the circuit body3may be connected to an electronic component or element different from the chip fuse3f. For example, as illustrated inFIG.13, the circuit body3of the present embodiment includes a branch portion31connected to a thermistor3s. The thermistor3sis fixed to the battery cell120and detects a temperature of the battery cell120. The detection result of the thermistor3sis output to the monitoring device via the connection conductor6.

The branch portion31illustrated inFIG.13has an extension portion38connected to the thermistor3s. The extension portion38extends from the fixed portion34to the thermistor3sin the first direction X. Two connection conductors6are routed in the branch portion31. One of the two connection conductors6is a voltage detection line connected to the busbar2via the chip fuse3f. The other of the two connection conductors6is a temperature detection line connected to the thermistor3sfrom the fixed portion34via the extension portion38. The extension portion38connects the fixed portion34and the thermistor3sin a flexurally deformed state. The thin portion3bmay be provided at the extension portion38. For example, the entire extension portion38may be the thin portion3b.

As described below, the case4of the present embodiment can hold the circuit body3in a state where the intermediate portion33is flexurally deformed. As illustrated inFIGS.14and15, the first protrusion46of the case4includes a shaft portion46aand an eaves portion46b. The shaft portion46ais a proximal end portion of the first protrusion46, and is connected to the first bridge portion41A. A shape of the shaft portion46ais a columnar shape along the third direction Z. The eaves portion46bprotrudes from a distal end of the shaft portion46a. A shape of the eaves portion46bis a columnar shape along the third direction Z. A value of an outer diameter of the eaves portion46bis, for example, the same as a value of an outer diameter of the shaft portion46a. The eaves portion46bis positioned on an axis different from an axis of the shaft portion46a, and is eccentric with respect to the shaft portion46a. The illustrated eaves portion46bis shifted with respect to the shaft portion46ain the first direction X.

Attachment of the circuit body3to the case4will be described with reference toFIGS.16and17.FIG.16illustrates a state in which the busbar2is accommodated in the busbar accommodating portion40. The busbar2is fixed to the fixed portion34in advance. An operator places the trunk portion30of the circuit body3on the bridge portion41of the case4and makes the busbar2be accommodated in the corresponding busbar accommodating portion40. The busbar accommodating portion40accommodates the busbar2and positions the busbar2and the fixed portion34. The shape of the intermediate portion33of the branch portion31at this time is a shape before being bent into an S-shape.

As indicated by an arrow Ar1inFIG.17, the operator inserts the first protrusion46into the first through-hole30eof the circuit body3while pulling the trunk portion30in the first direction X. The circuit body3is configured in such a manner that the intermediate portion33is curved into a desired S-shape when the first through-hole30eis positioned at the first protrusion46. Therefore, the operator can flexurally deform each intermediate portion33into an S-shape by inserting the first protrusion46into the first through-hole30e.

The operator hooks the first through-hole30eon the shaft portion46aof the first protrusion46. The outer diameter of the shaft portion46ais equal to an inner diameter of the first through-hole30e. Therefore, the shaft portion46acan position the trunk portion30at a predetermined position in the first direction X. The eaves portion46bprotrudes in a direction opposite to a direction of a reaction force F1generated by the branch portion31. Therefore, the eaves portion46brestricts the trunk portion30from being detached from the first protrusion46.

The first protrusion46locks the first end portion30cof the trunk portion30while being inserted into the first through-hole30e. The first protrusion46locks the first end portion30cagainst the reaction force F1and holds the first end portion30cat a predetermined position. With such a configuration, the first protrusion46can hold the circuit body3in a state where the intermediate portion33of the circuit body3is flexurally deformed.

As illustrated inFIGS.14and15, the case4includes an engaging piece48that positions the cover5in the first direction X. The engaging piece48protrudes from the first bridge portion41A in the third direction Z. The engaging piece48is disposed in the vicinity of the first protrusion46in the first direction X. A shape of the engaging piece48is similar to a shape of the engaging piece43. As illustrated inFIG.15, a claw portion48aof the engaging piece48protrudes in the first direction X. As illustrated inFIG.2, the cover5includes an engaging portion55corresponding to the engaging piece48. The engaging piece48is engaged with the engaging portion55to restrict relative movement of the cover5with respect to the first bridge portion41A.

In the busbar module1of the present embodiment, the curved shape of the intermediate portion33can be maintained by the second protrusion53of the cover5. As illustrated inFIG.18, the second protrusion53is coupled to the case4while being inserted into the second through-hole30fof the circuit body3. The second protrusion53limits a movement range of the second end portion30din the first direction X. A movable range of the second end portion30dis determined by a length L1of the second through-hole30f.

For example, in a case where the second end portion30dmoves relative to the cover5in a direction of an arrow X1, the second protrusion53locks the second end portion30d. The direction of the arrow X1is a direction in which the second end portion30dapproaches the first end portion30cin the first direction X. When the second end portion30dmoves in the direction of the arrow X1, flexure may occur at the trunk portion30. Therefore, the second protrusion53suppresses the movement range of the second end portion30dto suppress the flexure of the trunk portion30. The second protrusion53can maintain the desired curved shape of the intermediate portion33by limiting the movement of the second end portion30d.

As described above, the cover5of the present embodiment includes the flat cover main body50. The cover main body50is formed in a single plate shape and has high rigidity against a force in the first direction X. On the other hand, the case4can expand and contract in the first direction X so that the busbar2can follow the battery cell120. As described below, the cover5of the present embodiment can restrict the flexure of the trunk portion30caused by the expansion and contraction of the case4.

The cover5is engaged with the engaging piece48of the case4at the engaging portion55(seeFIG.2), and is positioned with respect to the first protrusion46. In other words, the engaging portion55is positioned with respect to the first through-hole30eof the circuit body3via the engaging piece48and the first protrusion46. Further, the cover5locks the second through-hole30fof the circuit body3by the second protrusion53. In this manner, the cover5is positioned with respect to one end of the trunk portion30and locks the other end of the trunk portion30, such that it is possible to appropriately suppress the flexure of the trunk portion30.

As illustrated inFIG.19, the branch portion31is fixed to the terminal21in a state where the fixed portion34faces the first surface21aof the terminal21. That is, the branch portion31is routed under the terminal21. A surface of the fixed portion34on which the chip fuse3fis mounted faces the first surface21aof the terminal21. The busbar2overlaps the fixed portion34so as to expose the chip fuse3fto the through-hole21c. As described above, the terminal21is fixed to the fixed portion34by being soldered to the pad35of the fixed portion34.

The through-hole21cof the terminal21is filled with a potting agent8. The potting agent8filling the through-hole21ccovers the chip fuse3fto protect the chip fuse3f. For example, the potting agent8fills the through-hole21cso as to cover each side surface and an upper surface of the chip fuse3f. Filling with the potting agent8may be made to protect a connecting portion between the pad35and the terminal21. The circuit body3and the busbar2are attached to the case4in a state where the intermediate portion33of the branch portion31is flexurally deformed into an S-shape. The busbar2is accommodated in the busbar accommodating portion40.

As illustrated inFIG.19, the branch portion31has a facing portion39. The facing portion39is a portion of the branch portion31that faces the first surface21aof the terminal21. The busbar2of the present embodiment has a groove-shaped recess22formed in the first surface21a. As described below, the busbar2having the recess22can suppress damage to the connection conductor6.

As illustrated inFIGS.19and20, the recess22is disposed at a position facing the connection conductor6of the branch portion31. As illustrated inFIG.21, the recess22extends in the first direction X from a side surface21dof the terminal21to the through-hole21c. A shape of the recess22when viewed in the first direction X is a rectangular shape or a trapezoidal shape. The terminal21illustrated inFIG.21has two recesses22. The two recesses22are disposed on both sides of the through-hole21cin the first direction X, respectively. Therefore, in the terminal21, the recess22can face the connection conductor6even in a case where the connection conductor6is routed on any side in the first direction X with respect to the through-hole21c.

As described above, the connection conductor6of the present embodiment is a metal foil such as a copper foil. In the branch portion31illustrated inFIG.20, the connection conductor6of the first circuit layer7A is connected to the busbar2. The illustrated connection conductor6is formed on the first surface10aof the base layer10. The first coating layer11is attached to the base layer10on which the connection conductor6is formed. The branch portion31is fixed to the busbar2in such a manner that the first coating layer11faces the first surface21aof the terminal21and the connection conductor6faces the recess22.

Since the recess22faces the connection conductor6, the connection conductor6is less likely to be damaged. For example, when the branch portion31vibrates or is bent, the connection conductor6is prevented from being damaged by the terminal21.

The first coating layer11may have a raised portion11acorresponding to the connection conductor6. A width of the recess22is larger than the width of the connection conductor6and a width of the raised portion11a. The width of the recess22is determined in such a manner that the recess22can face the connection conductor6even in a case where the connection conductor6is out of position due to tolerance, for example. A depth of the recess22is, for example, equal to or greater than a thickness of the connection conductor6. The depth of the recess22may be equal to or greater than a height of the raised portion11ain design.

In the busbar module1of the present embodiment, since the recess22is provided in the busbar2, leakage of the potting agent8can be suppressed. A comparative example in which the terminal21does not have the recess22will be described. In the comparative example, the raised portion11acomes into contact with the first surface10a, and a gap is generated in a wide range between the fixed portion34and the first surface10a. As a result, the potting agent8easily leaks out from the gap. On the other hand, in the busbar module1of the present embodiment, a portion of the first surface10aexcluding the recess22can be brought into contact with the fixed portion34or can be sufficiently close to the fixed portion34. Therefore, leakage of the potting agent8filling the through-hole21cis suppressed.

From the viewpoint of suppressing leakage of the potting agent8, it is preferable that the depth of the recess22is not excessively large. On the other hand, from the viewpoint of suppressing damage to the connection conductor6, the depth of the recess22is preferably not excessively small. The depth of the recess22is preferably determined within a range in which leakage of the potting agent8can be suppressed according to the viscosity of the potting agent8, for example. As an example, the depth of the recess22may be set to a maximum value at which leakage of the potting agent8can be suppressed.

Note that, as illustrated inFIG.13, the branch portion31of the circuit body3may include the branch portion31connected to the thermistor3s. In this case, each of two connection conductors6preferably faces the recess22of the terminal21. With such a configuration, the voltage detection line and the temperature detection line are less likely to be damaged by the terminal21.

As described above, the busbar module1of the present embodiment includes the plurality of busbars2and the plate-like circuit body3having flexibility. The busbar2is fixed to the battery cell120of the battery module110. The circuit body3includes a plurality of connection conductors6corresponding to the plurality of busbars2. The circuit body3includes the trunk portion30and the plurality of branch portions31. The trunk portion30extends in the first direction X in which the plurality of battery cells120are arranged. The plurality of branch portions31branch from the trunk portion30and are connected to the busbars2.

The circuit body3includes the first circuit layer7A and the second circuit layer7B. The first circuit layer7A is composed of the base layer10, the first coating layer11covering the first surface10aof the base layer10, and the first conductor layer13disposed between the first surface10aand the first coating layer11. The second circuit layer7B is composed of the base layer10, the second coating layer12covering the second surface10bof the base layer10, and the second conductor layer14disposed between the second surface10band the second coating layer12.

The branch portion31has the thin portion3bconfigured with any one of the first circuit layer7A and the second circuit layer7B. The branch portion31connects the trunk portion30and the busbar2in a state where the thin portion3bis flexurally deformed. The busbar module1of the present embodiment has the thin portion3bprovided at the branch portion31. Therefore, the busbar module1of the present embodiment can improve workability in an attachment process of fixing the busbar2to the battery cell120in a state where the branch portion31is flexurally deformed.

The branch portion31of the present embodiment includes the base portion32, the fixed portion34, and the intermediate portion33. The base portion32is a portion protruding from the trunk portion30in a direction intersecting the first direction X. The fixed portion34is a portion fixed to the busbar2. The intermediate portion33is a portion extending from the base portion32to the fixed portion34in the first direction X. The thin portion3bis provided at the intermediate portion33. In the branch portion31of the present embodiment, tolerance can be appropriately absorbed by the intermediate portion33having the thin portion3b.

The base portion32of the present embodiment includes both the first circuit layer7A and the second circuit layer7B. Since the rigidity of the base portion32is improved, it is easy to deform the intermediate portion33into a desired flexure shape.

The connection conductor6of the present embodiment is a metal foil. One of the first conductor layer13and the second conductor layer14included in the base portion32is composed of the connection conductor6. The other of the first conductor layer13and the second conductor layer14included in the base portion32is the reinforcing layer36formed of a metal foil. The reinforcing layer36is insulated from the connection conductor6. Since the connection conductor6and the reinforcing layer36are formed of metal foils, reinforcement of the base portion32is realized at low cost.

Note that the circuit body3is not limited to the flexible printed circuit board, and may be a flat cable (so-called FC), a flexible flat cable (so-called FFC), or the like.

The shape of the flexurally deformed intermediate portion33in a state where the busbar2is fixed to the battery cell120is not limited to the illustrated S-shape. The intermediate portion33may be flexurally deformed so as to be able to absorb positional deviation caused by tolerance.

Modified Example of Embodiment

A modified example of the embodiment will be described. By reducing the thickness of the first coating layer11or the second coating layer12, the rigidity of the thin portion3bmay be reduced. For example, in a case where the thin portion3bis composed of the first circuit layer7A, the thickness of the first coating layer11in the thin portion3bmay be smaller than the thickness of the first coating layer11in the thick portion3a.

The circuit body3may include another circuit layer in addition to the first circuit layer7A and the second circuit layer7B. In other words, the circuit body3may have a multilayer structure including six or more layers. For example, the thick portion3amay include a third circuit layer stacked on the first circuit layer7A or the second circuit layer7B. The third circuit layer includes, for example, a third conductor layer and a third coating layer. The thick portion3ain this case has a seven-layer structure.

The disposition and shape of the first protrusion46in the case4are not limited to the illustrated disposition and shape. For example, the first protrusion46may be disposed on the second bridge portion41B. In this case, the first through-hole30eis disposed at the second end portion30dof the circuit body3, and the second through-hole30fis disposed at the first end portion30c. The second protrusion53of the cover5is disposed at a position corresponding to the second through-hole30f.

The disposition and shape of the recess22are not limited to the illustrated disposition and shape. For example, a cross-sectional shape of the recess22may be an arc shape or a triangular shape.

A connection target to which the metal foil of the branch portion31is connected is not limited to an electronic component or element. For example, the metal foil of the branch portion31may be connected to the terminal21of the busbar2without interposing an electronic component or element therebetween.

The contents disclosed in the above embodiment and modified example can be appropriately combined and executed.

In the busbar module according to the embodiment, the branch portion has the thin portion composed of any one of the first circuit layer and the second circuit layer, and connects the trunk portion and the busbar in a state where the thin portion is flexurally deformed. With the busbar module of the embodiment, it is possible to implement both the multilayer structure of the connection conductor with the simple configuration and the flexibility of the branch portion.

Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.