JP4127501B2

JP4127501B2 - Battery connection structure, battery module, and battery pack

Info

Publication number: JP4127501B2
Application number: JP2002334856A
Authority: JP
Inventors: 不二夫平野
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2002-11-19
Filing date: 2002-11-19
Publication date: 2008-07-30
Anticipated expiration: 2022-11-19
Also published as: JP2004171856A

Description

【０００１】
【発明の属する技術分野】
本発明は、複数の単電池を接続して所要の出力電圧を得られる電池モジュールを構成するための電池間接続構造およびその電池間接続構造を用いて構成される電池モジュール並びにその電池モジュールを複数個配列して電気的に接続し、且つ機械的に連結して構成される電池パックに関するものである。
【０００２】
【従来の技術】
従来、複数の単電池を直列接続して所要の出力電圧を得る電池モジュールを構成するための電池間接続構造としては、以下に説明する第１ないし第３の従来技術が知られている。第１の従来技術は、図１４に示すように、２個の電池Ｂ１，Ｂ２の間に配置した皿状の接続体３を、一方の電池Ｂ１の正極端子となる金属キャップ１が設けられた封口板１０と、他方の電池Ｂ２の負極端子となる電池ケース２とにそれぞれプロジェクション溶接して接続した構成になっている（例えば、特許文献１参照）。
【０００３】
上記接続体３は、電池ケース２に外嵌される円筒部４と、封口板１０に当接される平面部７とを備えているとともに、円筒部４の内面と平面部７の下面とに、各々の同一半径上における９０°の等間隔の各位置にそれぞれプロジェクション溶接用突起８，９が形成されている。上記突起８，９を介してプロジェクション溶接することにより、接続体３の平面部７を、一方の電池Ｂ１における金属キャップ１と電気的接続された封口板１０に接続し、円筒部４を、他方の電池Ｂ２の電池ケース２に接続する。一方の電池Ｂ１の電池ケース２と接続体３との間は絶縁リング１１によって電気的に短絡するのが防止されている。これにより、両電池Ｂ１，Ｂ２は、電気的に直列接続されるとともに、機械的に相互に連結されている。
【０００４】
図１５は従来の電池モジュール５を示したものである。この電池モジュール５は、所要の出力電圧を得るのに必要な個数（同図には６個の場合を例示）の単電池Ｂ１〜Ｂ６のうちの隣接する各２個を、図１４の電池間接続構造によって直列接続することにより構成されている。
【０００５】
また、第２の従来技術は、第１の従来技術とほぼ同様の構成を有するものであり、第１の従来技術と異なる点は、第１の従来技術の接続体３とほぼ同様の皿状接続体の中央連結部（平面部）およびフランジ部（円筒部）にそれぞれ圧接凸部を設けて、その圧接凸部を介して皿状接続体を２個の単電池にレーザ溶接して接続する構成のみである（例えば、特許文献２参照）。
【０００６】
さらに、第３の従来技術は、第１および第２の従来技術のような接続体を用いずに、複数の電池間を直接的に接続するものである（例えば、特許文献３参照）。すなわち、電池ケースの開口部を閉塞する封口体に、電池軸外方に突出する接続電極部を形成し、隣接する２個のうちの一方の単電池の接続電極部を、これに設けた複数個のプロジェクション溶接用突起を介して他方の単電池の電池ケースの開口部とは反対側の底面部にプロジェクション溶接により直接連結して、複数の単電池を各々の電池軸方向に一列に並ぶ配置で直列接続するものである。
【０００７】
上記第１ないし第３の従来技術の電池間接続構造の何れかを用いて構成された電池モジュールは、多数本を電気的に直列接続して高圧電力を取り出せる電池パックに構成される。このような高圧電力を得られる電池パックは、例えば、内燃機関と電池駆動モータとを組み合わせて走行源としたハイブリッドタイプの電気自動車の上記モータの駆動電源などに用いられる。この種の従来の電池パックとしては、以下に説明する第４および第５の従来技術にそれぞれ開示されたものが知られている。
【０００８】
上記第４の従来技術に係る電池パックは、上方が開口した方形状箱形となったプラスチック製ホルダーケースに、図１５に示したような電池モジュール５を複数列多段に配置して内蔵した構成になっている（例えば、特許文献４参照）。ホルダーケースは、全体の外径が細長い円柱状となった電池モジュール５を挿入するための円形の貫通孔が両端壁に電池モジュールの収納数だけ形成されているとともに、電池モジュールを安定に保持するための中間壁が両端壁間にこれらと平行に設けられており、この中間壁にも円形の貫通孔が両端壁と同数だけ開口されている。電池モジュールは、両端壁と中間壁の各貫通孔に挿入してホルダーケースの定位置に保持されている。
【０００９】
また、第５の従来技術に係る電池パックは、複数の電池モジュールを平行な配置で内部に保持するホルダーケースを備え、このホルダーケースは、両面に配設された蓋ケースと、この両蓋ケースの間に配設された中間ケースとを備えている（例えば、特許文献５参照）。上記ホルダーケースは、中間ケースの両面と蓋ケースの内面とに、電池モジュールを複数列複数段に並べて保持するためのホルダーリブが突設されているとともに、両面の蓋ケースと中間ケースとを連結して、ホルダーリブで複数列複数段の電池モジュールを両側から挟着して定位置に保持している。
【００１０】
【特許文献１】
特開平１０−１０６５３３号公報
【００１１】
【特許文献２】
特開２０００−１２６７０３号公報
【００１２】
【特許文献３】
特開２０００−１４９９０７号公報
【００１３】
【特許文献４】
特開平１０−２７０００６号公報
【００１４】
【特許文献５】
特開２０００−２２３０９６号公報
【００１５】
【発明が解決しようとする課題】
しかしながら、上記第１の従来技術に係る電池間接続構造を用いて構成した電池モジュール５は、複数本の単電池Ｂ１〜Ｂ６をこれらの電池軸方向に並べて連結した細長い円柱状の外形となるので、全体の外形、長さおよび平行度を高い精度で作製するのが極めて困難である。また、プロジェクション溶接は、接続体３の円筒部４のプロジェクション溶接用突起８を円形の電池ケース２の外面に接触させた不安定な姿勢で行わなければならないために、電池モジュール５の歩留りの低下を招いている。しかも、溶接回数は、各単電池Ｂ１〜Ｂ６のうちの隣接する各２個間を１個の接続体３で接続する際に、電池ケース２と接続体３間がシリーズ溶接方式で４回と、接続体３と封口板１０間がシリーズ溶接方式で２回とが必要であり、この溶接回数の多さに伴って生産性が悪い。また、隣接する各２個の単電池Ｂ１〜Ｂ６間には接続体３を介した経路を通って電流が流れるので、電流経路が長くなり、その長くなった分だけ電気抵抗が大きくなる。
【００１６】
さらに、接続体３および絶縁リング１１は隣接する各２個の単電池Ｂ１〜Ｂ６間毎に装着するので、部品コストが高くなるとともに、接続体３および絶縁リング１１の装着工程を要することから、生産性がさらに低下する。また、この電池モジュールは電気自動車や電動自転車などのような振動する環境下で使用されることが多いが、これらの単電池Ｂ１〜Ｂ６の連結構造では、単電池Ｂ１〜Ｂ６間の曲げ強度が低く、且つ連結の機械的強度も不十分であるから、過酷な振動や衝撃を受けたときに、接続体３が破壊して単電池Ｂ１〜Ｂ６間の接続が外れ易い欠点がある。
【００１７】
また、第２の従来技術に係る電池間接続構造を用いて構成した電池モジュールは、第１の従来技術とほぼ同様の構成を有していることから、電池モジュールとしての外形、長さおよび平行度を極めて高い精度で作製するのが困難であり、レーザー溶接を不安定な状態で行うことから、歩留りが低く、溶接回数が多いのに伴って生産性が低く、接続体や絶縁リングを必要とするのに起因して部品コストが高くなり、且つ工数が多くなるのに伴って生産性がさらに低下し、過酷な振動や衝撃を受けたときに、接続体が破壊し易いという、第１の従来技術と同様の欠点がある。しかも、この電池モジュールでは、接続体として、振動を受けたときにも破壊しないように厚みの大きなものを使用した場合に、封口体に応力が加わって封口体の気密性が損なわれるおそれがある。
【００１８】
さらに、第３の従来技術に係る電池間接続構造を用いて構成した電池モジュールは、第１および第２の従来技術の電池モジュールに比較して、接続体や絶縁リングが不要となり、且つ溶接回数も少なくて済むので、コストダウンできる利点がある反面、この電池モジュールは、単電池同士を直接溶接して連結することから必然的に、振動や側方からの衝撃を受けたときの機械的強度や曲げ強度が第１および第２の従来技術のものに比較してさらに低いので、電気自動車や電動自転車などの過酷な振動を受ける環境下で使用する場合には、例えば、ホルダーケース内に極めて堅牢な保持形態で収容する必要があり、そのような構成とした場合には、結局コスト高になってしまう。
【００１９】
一方、従来の電池パックは、上記第１ないし第３の従来技術に係る電池モジュールの何れかを所要本数だけ配列接続して構成されているが、上記第４の従来技術に係る電池パックでは、両端壁と中間壁の両方に貫通孔を有するホルダーケースの成形金型が、上記形状を形成する部分において簡単に脱型出来ないことから、複雑な構造となり、ホルダーケースの製造に手間がかかって製造コストが高くつく。また、電池モジュールは、電池間接続部分において接続体３および絶縁リング１１が電池ケース２の外方に出っ張る形態となって全体にわたり外径が一定でないから、ホルダーケースの両端壁と中間壁の各貫通孔を高精度に形成したとしても、全ての電池モジュールを貫通孔に隙間無く挿入して保持することができないので、電池モジュールをがたつきなく安定に保持できない。しかも、電池モジュールを小さな貫通孔に挿入して取り付ける作業は非常に手間がかかるので、生産性が悪い。さらに、電池モジュールの収納個数が変更された場合には、ホルダーケースを新たな成形金型で製作する必要があるので、さらに大きなコスト高となる。
【００２０】
また、第５の従来技術に係る電池パックでは、ホルダーケースを構成する蓋ケースと中間ケースの何れかに反りなどの変形が少しでも生じた場合に、全ての電池モジュールを均等に保持するのが困難となる。そこで，蓋ケースおよび中間ケースには、反りなどの変形を生じさせず、且つホルダーリブの形状およびホルダーリブ間の寸法を高精度に製作することが要求されるので、材料コストおよび製作コストが高くつく。
【００２１】
そこで、本発明は、上記従来の課題に鑑みてなされたもので、容易な工程で安価に構成しながらも、電気抵抗の低減を図れる電池間接続構造と、振動や衝撃に対しても強い堅牢な構成を備えた電池モジュールと、多数個の電池モジュールを容易、且つ確実に接続して所要構成とできる電池パックとを提供することを目的とするものである。
【００２２】
【課題を解決するための手段】
上記目的を達成するために、本発明に係る電池間接続構造は、一方の電極を兼ねる有底円筒状の電池ケースと、前記電池ケースの開口部に対し電気絶縁状態で閉塞して他方の電極を兼ねる封口体とを有するとともに、前記封口体の外周近傍箇所に電池軸方向外方に突出するリング状の接続電極部が形成された単電池を複数個備え、前記各単電池が各々の電池軸が平行となる配置で並置されるとともに、導電接続すべき隣接単電池は、その向きが反対となるように配置され、平板状の接続板が、隣接する各２個のうちの一方の前記単電池の前記接続電極部と他方の前記単電池の前記電池ケースの底面とに架け渡す状態に載置されて、前記接続電極部と前記電池ケースの底面部との各々の互いに近接する箇所に溶接により接続されており、前記接続板が、少なくとも前記接続電極部を包含できる円弧形状を有して前記単電池に溶接される一対の接続部と、前記円弧形状の径よりも小さい幅のほぼ矩形状を有して一対の前記接続部を相互に接続する連結部とを一体に備えた平面視でほぼ瓢箪形状であって、少なくとも前記連結部の両側辺からそれぞれ直交方向に延びる一対の補助片を備えていることを特徴としている。
【００２３】
この電池間接続構造では、単なる平板状である接続板の両側部を、各々の電池軸が平行となる配置で並置された２個の単電池のうちの一方の単電池のリング状の接続電極部と他方の単電池の電池ケースの底面とに架け渡して支持された安定姿勢で溶接を行えるので、接合不良といった不具合が生じるおそれがなく、歩留りが大幅に向上する。また、接続部と接続電極部の間および接続部と電池ケースの底面の間とをそれぞれ接合するための溶接を合計２回行えばよく、溶接回数が大幅に削減されて生産性が格段に向上する。さらに、単電池をこれらの電池軸に平行とした配置で並置したことにより、２個の単電池間における電流経路は、一方の単電池のリング状の接続電極部と他方の単電池の底面の外周部分との互いに近接した箇所とを結ぶ最短距離となり、電気抵抗を大幅に低減できる。
【００２４】
また、隣接する各２個の単電池間に架け渡す接続板は、隣接する２個の単電池全体の外形に対応するほぼ瓢箪形状であって、２個の単電池間の隙間を塞がないので、この電極間接続構造を電池モジュールの構成した場合には、各単電池の周囲に均等な断面積を有して電池軸方向に沿った放熱用通路を効果的に構成できる。また、接続板の連結部は、小さな幅に形成されているが、両側辺に設けた補助片によって電気抵抗が高くなるのを抑制される。しかも、接続板は、補助片によって機械的強度が向上する利点がある。
【００２５】
上記発明の電池間接続構造において、電池ケースの底面部の中央部に、内方に向け凹む凹部が形成され、接続板の一方の接続部が、前記電池ケースの底面部における凹部の外側であって、隣接する単電池の近接箇所に溶接されている構成とすることが好ましい。
【００２６】
この構成によれば、凹部を形成したことによって電池ケースの底面部と負極集電体との間に僅かな隙間を設けることができるから、電池ケースの底面部と接続板とを例えばプロジェクション溶接するときに底面部が熱影響によって内方に膨出する状態に変形しても、この変形する底面部が上記隙間の存在によって負極集電体や極板群に対し悪影響を及ぼすことがないので、所要の電池容量と安定した電池性能とを確保することができる。
【００２７】
また、上記発明の電池間接続構造において、接続板が、Ｎｉ−Ｃｕ−Ｎｉの三層のクラッド材からなる平板の一体成形品とすることが好ましい。これにより、接続板は、中央のＣｕ層によって良好な導電性を確保しながらも、両面のＮｉ層を電池ケースの一般的な素材であるニッケルめっき鋼板に対し好適に溶接できるので、電気抵抗を一層低減でき、接続体での電力損失を最小限に抑えることができる。
【００２８】
また、上記発明の電池間接続構造において、接続板は、平面視でほぼ瓢箪形状をこれの長手方向に沿って２分割した同一形状の一対からなり、隣接する各２個の単電池は、少許の間隙で近接対向する配置で架け渡された一対の前記接続板の各々の両側部分がそれぞれ溶接されて、この両接続板を介して電気的に接続されている構成とすることもできる。
【００２９】
この構成によれば、一対の接続板を単純な形状としても、この一対の接続板を近接対向して配置することで、両接続板の間に溶接時に必要な透孔やスリットと同じ形状を形作ることができるので、単純な形状の接続板を安価に大量生産できる。しかも、接続板を２個の電池に例えばプロジェクション溶接して溶着する場合には、溶接時の無効分流を完全に無くすことができる大きな利点がある。
【００３０】
さらに、上記発明の電池間接続構造において、接続板は、隣接する２個の単電池との各接触箇所における少なくとも互いに近接する箇所に絞り薄肉部が形成されているとともに、前記絞り薄肉部を介してレーザー溶接またはビーム溶接されて前記単電池に溶着されている構成とすることもできる。
【００３１】
この構成によれば、隣接する２個の単電池間の電流経路の距離を最短として電気抵抗を大幅に低減できるのに加えて、絞り薄肉部に光線を照射してレーザー溶接またはビーム溶接を行うことにより、絞り薄肉部が先に溶融して溶接箇所に十分な熱を付与することができるので、十分な溶接強度を確保することができ、溶接の信頼性が向上する。
【００３２】
さらにまた、上記発明の電池間接続構造において、接続板の長手方向に沿った両側辺から直交方向に延びる一対の補助片は、連結部から両側の接続部の少なくとも半部までそれぞれ延びる長さを有し、前記接続板は、前記補助片が単電池とは反対方向を向く配置で隣接する２個の単電池に架け渡して、前記両単電池に溶接されている構成とすることが好ましい。
【００３３】
この構成によれば、接続板は、補助片が単電池に対し何ら干渉しない配置で２個の単電池間に架け渡して溶接されることから、長手方向に沿った中央線に対し線対称の形状とできるので、２個の単電池に取り付ける際に方向性が無く、取付作業が容易となる。また、補助片は、可及的に長く形成されているので、接続板としての機械的強度が一層向上する。
【００３４】
さらにまた、上記発明の電池間接続構造において、接続板の両側辺から直交方向に延びる一対の補助片は、連結部から両側の接続部の少なくとも半部まで延びる長さを有するとともに、各々の一端側が電池ケースの外面に沿って接触する湾曲形状で、且つ各々の他端側が接続電極部の外面に沿って接触する湾曲形状に形成されている構成とすることが好ましい。
【００３５】
この構成によれば、接続板は、２個の単電池間に架け渡されたときに、電池ケースの外面と接続電極部とによって両単電池に対し仮止め状態に固定されるから、次工程の溶接を容易、且つ正確に行うことができるとともに、接続板による２個の単電池の連結構造の機械的強度が一層向上する利点がある。
【００３６】
本発明に係る電池モジュールは、単電池の電池軸方向の長さのほぼ半分の厚みを有するほぼ直方体の外形を有して、内部に円筒形の前記単電池を収納できる断面四角形状で、且つ前記厚み方向に貫通する複数の電池収納部が一列配置または複数列配置に形成された合成樹脂製の一対のケース半体を有するホルダーケースを備え、前記ホルダーケースは、前記両ケース半体が各々の対応する前記各電池収納部がそれぞれ相互に連通して前記単電池の全体を収納できる電池収納部が複数形成される相対位置で相互に固着されてなり、前記各収納部に個々に挿入された前記各単電池が、前記両ケース半体の各々の電池収納部の外方側縁部から前記電池収納部内に突設された保持突部が電池軸方向の両端面に当接されて抜け止めされた状態で前記電池収納部内に収納され、隣接する各２個の前記単電池が、請求項１ないし６の何れかに記載の電池間接続構造によって相互に電気的に接続され、且つ機械的に連結され、前記ホルダーケースの厚み方向の両側の開口部がこれに固着された蓋部材でそれぞれ閉塞され、前記各蓋部材に、前記単電池と断面四角形の前記電池収納部の４つの隔壁との各間の空隙にそれぞれ対応する箇所に前記各空隙に対応する形状の放熱用孔が形成されたことを特徴としている。
【００３７】
この電池モジュールでは、一対のケース半体を、これらの各電池収納部内に個々に単電池を挿入した状態で相互に連結して、ホルダーケースを構成したときに、両ケース半体の各々の電池収納部内に収納された単電池が保持突部によって抜脱不能に保持されて、ホルダーケースが所要個数の単電池を収納したブロック形態となるから、次工程において隣接する各２個の単電池間に接続板を架け渡して溶接する作業を極めて容易に行え、生産性が格段に向上する。
【００３８】
また、この電池モジュールでは、合成樹脂製のホルダーケースの成形精度によって外形寸法が一義的に決定されて、組立工程を経たのちに寸法ばらつきなどが生じることがなく、形状的に高精度なものとなる。また、各単電池は、個々の電池収納部内に収納されることによって完全に電気絶縁された状態に保持されるので、従来の電池モジュールにおける絶縁リングや樹脂製外装チューブなどが不要となり、材料コストの低減と生産性の向上とを図ることができる。また、接続板は、２個の単電池全体の外形に対応する瓢箪形状であって電池間の空隙を塞がないので、各単電池と電池収納部の４つの隔壁との各間には、均等な断面積の空隙が形成され、これらの空隙が両側の蓋部材の放熱用孔を介してホルダーケースの外部に連通されるので、ホルダーケースの一面側から各単電池の各々の周囲をそれぞれ通って他面側に貫通する効果的な放熱用通路が形成され、各単電池は、放熱用通路内を流通する風によって極めて効果的に冷却され、しかも、比較的多数個の単電池の全てを均等に冷却することができる。
【００３９】
上記発明の電池モジュールにおいて、ホルダーケースは、両ケース半体がこれらの開口端面間に矩形状の弾性体シートを介在させて相互に結合されてなる構成とすることが好ましい。これにより、製造に際して、両ケース半体をこれらの電池収納部内に単電池を挿入して相互に合体させるときに、単電池の電池軸方向の高さのばらつきを弾性体シートの弾力変形で吸収でき、ブロック形態のホルダーケースを容易に組み立てることができる。また、電池モジュールとして機能する際には、ホルダーケースの外部から加わる衝撃や振動が弾性体シートで吸収されて各単電池に直接作用しないので、特に、電気自動車や電動自転車あるいは電動工具などの過酷な振動や衝撃が加わり易い環境下に装着して用いる場合においても、各単電池を保護した状態で確実に保持することができる。
【００４０】
また、上記発明の電池モジュールにおいて、ホルダーケースの電池収納部は、断面四角形を形成する４つのうちの３つの第１の隔壁の幅が単電池の外径よりも大きく、且つ他の１つの第２の隔壁の幅が前記単電池の外径に等しい平面視長方形の形状に形成され、前記第１の各隔壁の各々の内面に、各々の先端間の距離および前記第２の隔壁までの距離がそれぞれ前記単電池の外径と等しい突出長に設定された３つの支持リブが突設されている構成とすることが好ましい。
【００４１】
この構成によれば、支持リブの突出長分だけ単電池と電池収納部の隔壁との間の空隙の容積が拡大して、空隙を流通する風量が増大するとともに、平面視長方形の電池収納部の４つの角部において、単電池と電池収納部の４つの隔壁との間に互いにほぼ同じ容積を有する空隙が形成される。これにより、ホルダーケースの一面側から各単電池の各々の周囲をそれぞれ通って他面側に貫通する均等な放熱用通路が各単電池の周囲に形成されるから、比較的多数個の単電池の全てが均等、且つ効率的に冷却される。そのため、この電池モジュールを多数個用いて構成する電池パックでは、従来の電池パックに備えられている冷却フィンブレードなどの冷却機構が不要となる。
【００４２】
さらに、上記発明の電池モジュールにおいて、３つの支持リブに、これの外方端から電池収納部の内方にそれぞれ突出して電池ケースの電池軸方向の端面に当接する保持突部が一体に突設され、前記各電池収納部の各々の両側開口に位置して相対向する各２つの前記保持突部は、前記単電池の電池軸方向の両端面間の長さに等しい離間距離に設定して配設されている構成とすることが好ましい。
【００４３】
この構成によれば、支持リブによって単電池と電池収納部の隔壁との間に比較的大きな容積の空隙を形成しながらも、保持突部の電池収納部内への突出長を短く設定することができる、また、各単電池は、対向する一対の支持リブと他の支持リブと電池収納部の対向隔壁との４箇所に電池ケースの外面が接触して電池軸方向に対し直交方向にがたつきなく保持されるとともに、電池軸方向の両端面に保持突部が直接当接して電池軸方向にがたつきなく保持されるから、比較的多数個の単電池を収納しながらも、各単電池は、電池モジュールを電気自動車や電動自転車あるいは電動工具などの過酷な振動や衝撃が加わり易い環境下に装着した場合においても、保護された状態で確実に保持され、破壊などが生じるおそれが全くない。
【００４４】
さらにまた、上記発明の電池モジュールにおいて、一対のホルダーケースの少なくとも一方における電池収納部の配設方向の一端部または両端部に、外部接続用の正極端子および負極端子がインサート成形によりそれぞれ設けられて、前記正極端子および負極端子とこれらにそれぞれ隣接する単電池とが接続板により相互に接続され、前記両ケースにおける前記配設方向に対し直交方向の両側部に、固定部材により相互に連結される連結部材がインサート成形によりそれぞれ設けられている構成とすることが好ましい。
【００４５】
この構成によれば、正極および負極端子並びに連結材料がインサート成形によりホルダーケースに一体に設けられているので、部品点数の削減に伴って組立工数が低減する。また、ほぼ直方体の外形を有するホルダーケースの外部にインサート成形された連結部材を一体に備えているので、所要個数の単電池を単に電池軸方向に直列接続しただけの従来の電池モジュールとは異なり、正極端子および負極端子を所定の電極端子に接続し、且つ連結部材を介して機器などの取付部に固定することにより、そのままで各種機器などの駆動電源として用いることも可能である。
【００４６】
本発明に係る電池パックは、本発明の何れかに係る電池モジュールのホルダーケースに、単電池の配設方向に沿った両側辺にそれぞれ複数個の取付部材がインサート成形により設けられ、２個の前記電池モジュールのうちの一方に対し他方が厚み方向の向きを反転させた相対位置で重ね合わせて構成された電池モジュールユニットが複数個並置され、複数個の前記電池モジュールユニットの周囲を被覆する少なくとも２枚の外装プレートが、相対向する各２個の前記取付部材にそれぞれ挿通された固定部材で相互に連結され、且つ前記電池モジュールに固着されているとともに、前記各電池モジュールユニットの各々の２個の前記電池モジュールが前記固定部材で一体化され、前記各電池モジュールの各々の外部接続用の正極端子および負極端子がバスパーで電気的接続されて、各電池モジュールにそれぞれ内蔵の各単電池が直列接続または並列接続されていることを特徴としている。
【００４７】
この電池パックでは、電池モジュールがホルダーケースの成形精度で一義的に決定される極めて高精度な外形を有し、且つ比較的多数個の単電池がホルダーケース内に安定に収納保持されていることにより、その電池モジュール同士を固定ねじなどの固定部材による簡単な固定手段で容易に連結して電池モジュールユニットを構成することができるとともに、複数の電池モジュールユニットを、これの回りに配置した少なくとも２枚の外装プレートに固定ねじなどの固定部材による簡単な固定手段で容易に一体化しながらも、非常に堅牢な構造に容易に組み立てできる。そのため、この電池パックは極めて高い生産性で製造することがてきる。また、この電池パックでは、２枚の外装プレートを相互に連結する固定部材を一対の電池モジュールの固定用にも兼用しているので、固定部材の個数および連結作業の工数を共に低減できる利点がある。
【００４８】
また、電池モジュールが多数個の単電池を安定に保持したブロック形態となっていることから、電池モジュールの個数を変更する場合には、板材を屈曲して形成できる外装プレートの形状を変更するだけでよく、従来の電池パックのように新たな金型でホルダーケースを成形するのに比較して、極めて安価に対応できる。さらに、電池モジュールユニットにおける重ね合わされた２個の電池モジュール間においても、各々の電池モジュールの放熱用通路が連通されるから、多数個の電池モジュールを一体化した場合にも、個々の単電池の冷却機能が確実に確保されるので、従来の冷却フィンブレードなどの冷却機構が不要となる。
【００４９】
上記発明の電池パックにおいて、少なくとも２枚の外装プレートに、電池モジュールの取付部材が当接されて固定部材で連結される複数の設置面と、この設置面の各間が外方に向け膨出することによって内部に形成された凹所とを有し、前記凹所と前記電池モジュールとの間に、前記電池モジュールの電池収納空間に蓋部材の放熱用孔を介して連通する放熱用通路が形成されている構成とすることが好ましい。
【００５０】
この構成によれば、外装プレートの凹所と電池モジュールとの間に形成される放熱用通路を電池モジュールの電池収納空間に連通させた構成を有しているので、電池モジュールと外装プレートとの間に効果的な放熱用通路を形成できるので、多数個の単電池を極めて効率的に、且つ全てを均等に冷却することができ、従来の電池パックに備えていた温度センサや送風機などが不要となり、相当のコストダウンを図ることができるとともに、所要の冷却効果を得ながらも全体形状を小形化できる。
【００５１】
【発明の実施の形態】
以下、本発明の好ましい実施の形態について図面を参照しながら説明する。図１は本発明の一実施の形態に係る電池モジュール１２の各構成要素の相対配置を示した分解斜視図である。この実施の形態では、共に同一種類で同一規格の２０個の円筒形単電池１３を直列接続する場合を例示してあり、この単電池１３は、例えば、ニッケル水素二次電池である。
【００５２】
先ず、上記電池モジュール１２に適用する単電池１３の構成について説明する。図２（ａ）は単電池１３を示す斜視図、（ｂ）は（ａ）のＡ−Ａ線断面図である。負電極を兼ねる電池ケース１４は、一端が開口した有底円筒状の形状を有しており、この電池ケース１４内には、周知の正極板と負極板とをこれらの間にセパレータを介在させて渦巻状に巻回してなる極板群１７および電解液（図示せず）が収納されている。また、電池ケース１４の開口部は、封口板１９、絶縁ガスケット２０、金属キャップ２１およびゴム弁体２２により構成される封口体１８によって閉塞されている。
【００５３】
すなわち、上記封口板１９は、その周縁部を絶縁ガスケット２０を介して電池ケース１４に対し電気的に絶縁されて、かしめ加工された電池ケース１４の開口部に絶縁ガスケット２０を介して固着されており、これにより、電池ケース１４の開口部が閉塞されている。上記封口板１９には、電池軸方向外方に向け突出する平面視リング状の接続電極部２８が周端近傍箇所において同心状の配置で形成されている。極板群１７から引き出された正極リード２６は封口板１９に接続されている。したがって、封口板１９に形成された上記接続電極部２８は正極端子となる。また、負電極となる電池ケース１４の底面中央部には、内方に向け凹んだ円形の凹部２９が同心状の配置で形成されている。
【００５４】
ゴム弁体２２は、封口板１９の中央部の凹所２３と金属キャップ２１との間に形成された空間内に収納されて、凹所２３に穿孔されたガス排出孔２４を閉塞している。このゴム弁体２２は、電池内部のガス圧力が異常に上昇して弁開放圧に達したときに、ガス排出孔２４を通じて作用するガス圧力を受けて弾性変形し、ガス排出孔２４を開放する。それにより、電池内部のガスは、ガス排出孔２４および金属キャップ２１のガス排出孔２７を通じて電池ケース１４の外部に排出される。
【００５５】
図１に戻って、上述の各単電池１３は、上部ケース半体３０Ａと下部ケース半体３０Ｂとがこれらの間に弾性体シート３６を介在させて相互に合体されてなるホルダーケース３０内に収納される。両ケース半体３０Ａ，３０Ｂは、共に合成樹脂製であって、何れも単電池１３の電池軸方向の長さの半分よりも僅かに大きな厚み（高さ）を有するほぼ直方体の外形を有し、その内部が隔壁で仕切られて、２０個の単電池１３の各々の半部を個々に収納できる電池収納部３１がそれぞれ１０個２列に配設されている。各電池収納部３１は、四つの隔壁で囲まれた平面視長方形の形状を有するとともに、厚み方向に貫通している。なお、両ケース半体３０Ａ，３０Ｂの電池収納部３１は、共にほぼ同一形状を有しているので、同一の符号を付してあり、この電池収納部３１Ａ，３１Ｂの詳細については後述する。弾性体シート３６は、両ケース半体３０Ａ，３０Ｂの突き合わせ開口端面に対応した平面視長方形状を有している。
【００５６】
上部ケース半体３０Ａにおける各電池収納部３１の配設方向（長手方向）の一端側（図の左端側）外面には、ナットからなる外部接続用正極端子３２および外部接続用負極端子３３がインサート成形により一体に設けられているとともに、他端側（図の右端側）外面にも、ナットからなる外部接続用正極端子３２および外部接続用負極端子３３が、一端側とは反対の配置でインサート成形により一体に設けられている。さらに、両ケース半体３０Ａ，３０Ｂの上記配設方向に沿った両側外面には、ナットからなる連結部材３４がそれぞれ複数個（実施の形態では３個を例示）ずつ配置されてインサート成形により一体に設けられているとともに、連結部材３４の各間には、パイプからなる取付部材４５がそれぞれ複数個（実施の形態では２個を例示）ずつ配置されてインサート成形により一体に設けられている。各連結部材３４は、上下両方から固定ねじをねじ込めるようになっている。取付部材４５は固定ねじを単に挿通させる小径のパイプからなる。
【００５７】
各単電池１３は、両ケース半体３０Ａ，３０Ｂが合体されてなるホルダーケース３０の各電池収納部３１内にそれぞれ個々に挿入されて、各々の電池軸が互いに平行となる配置で保持された状態で、図の前方列および後方列において配列方向で隣接する各２個がそれぞれ接続板３８によって交互に順次連結されることにより、直列接続される。但し、図における後方列左端の単電池１３は、自体の電池ケース１４の底面部が接続板３８を介して外部接続用正極端子３２に接続され、前方列左端の単電池１３は、自体の接続電極部２８が接続板３８を介して外部接続用負極端子３３に接続される。また、図における後方列右端の単電池１３は、自体の接続電極部２８が接続板３８を介して外部接続用負極端子３３に接続され、前方列右端の単電池１３は、自体の電池ケース１４の底面部が接続板３８を介して外部接続用正極端子３２に接続される。
【００５８】
図３は、同上の電池モジュールにおける単電池１３の接続に適用した本発明の一実施の形態に係る電池間接続構造を示し、（ａ）は平面図、（ｂ）は正面図、（ｃ）は（ａ）のＢ−Ｂ線で切断した拡大断面図である。上記接続板３８は、Ｎｉ−Ｃｕ−Ｎｉの三層のクラッド材の平板からなり、接続電極部２８の外径にほぼ等しい径の円弧状となった一対の接続部３５と、この両接続部３５の相対向する箇所を相互に接続する直線状の連結部４１とを有する一体物である。連結部４１の幅は、接続部３５の径よりも十分に小さく設定されている。したがって、接続板３８は、中央部がくびれて、平面視でほぼ瓢箪形状になっている。
【００５９】
上記の一対の接続部３５には、接続電極部２８の内径にほぼ等しい径の透孔３９が形成され、且つ透孔３９における径方向の対向両側から接続板３８の長手方向に沿って両外方に向けそれぞれ延びるスリット４０が形成されている。さらに、一対の接続部３５には、４個のプロジェクション溶接用突起４２が透孔３９の外側の同一円上における９０°の等間隔の位置に予め形成されている。さらに、接続板３８の両側辺には、連結部４１から両側の各接続部３５の半部までを包含する長さの補助片２５が連結部４１および接続部３５に対し直角に屈曲して形成されている。したがって、接続板３８は、長手方向の中央部に対し線対称の形状になっている。この接続板３８は、一対の補助片２５を外方に向けた配置で隣接する２個の単電池１３に架け渡して取り付けられるが、接続板３８が長手方向の中央部に対し線対称の形状であるから、その取り付けに際して方向性がないので、容易に取り付けできる。また、この実施の形態では、接続板３８が突起４２を介してプロジェクション溶接する場合を例示してある。
【００６０】
上記電池間接続構造では、隣接する２個の単電池１３間に接続板３８を架け渡す状態に載置したときに、接続板３８の一方側（図３の左側）の４個のプロジェクション溶接用突起４２が単電池１３の接続電極部２８上に当接し、且つ他方側（図３の右側）の４個の突起４２が単電池１３の底面部における凹部２９の周囲箇所に当接し、この状態で周知のプロジェクション溶接が行われる。このプロジェクション溶接は、単なる平板状である接続板３８の両側の接続部３５が、各々の電池軸が平行となる配置で並置された２個の単電池のうちの一方の単電池１３のリング状の接続電極部２８と他方の単電池１３の電池ケース１４の底面部とに架け渡して支持された安定姿勢で行えるので、上述した従来の電池間接続構造のような不安定な姿勢での溶接による接合不良といった不具合が生じるおそれがなく、歩留りが大幅に向上する。
【００６１】
また、プロジェクション溶接に際しては、図３の左方の単電池１３において、例えば、正側溶接電極を接続電極部２８の側面に接触させ、且つ負側溶接電極を接続板３８における突起４２の対向箇所に接触させて、両溶接電極間にインバータ直流電源より高電圧を印加する。これにより、溶接電流は、接触面積が小さいことから接触抵抗が極めて小さい突起４２と接続電極部２８との間に局部的に集中して流れ、それによる発熱によって４個の突起４２が溶融し、接続部３５と接続電極部２８とが完全に密着した状態で突起４２が溶けたナゲットを介して互いに溶着される。ここで、接続板３８の各接続部３５と接続電極部２８とは、１回のプロジェクション溶接により４個の突起４２を介して強固に接合できる。
【００６２】
また、図３の右方の単電池１３においても、負側溶接電極を電池ケース１４の外周面に接触させ、且つ正側溶接電極を接続板３８における突起４２の対向箇所に接触させて、両溶接電極間にインバータ直流電源より高電圧を印加することにより、接続板３８と電池ケース１４の底面部とを１回のプロジェクション溶接により４つの突起４２が溶融したナゲットを介して強固に接合できる。
【００６３】
したがって、隣接する各２個の単電池１３は、２回のプロジェクション溶接によって互いに接続できるので、例えば図１４に示した従来の電池間接続構造では計８回の溶接工程を繰り返すのに比較して、この実施の形態において２０個の単電池１３における隣接する各２個の各単電池１３間を２回の溶接により接続できるので、溶接回数を大幅に削減することができ、それに伴って生産性が格段に向上する。また、上記プロジェクション溶接時には、透孔３９および一対のスリット４０によって無効分流を格段に低減することができる。
【００６４】
さらに、上記電池間接続構造では、一方の単電池１３のリング状の接続電極部２８と他方の単電池１３の凹部２９の外側の外周部分との互いに近接した箇所に接続板３８の両側の接続部３５を溶接することから、図３（ａ）に示す隣接する２個の単電池１３間の電流経路の距離Ｌを最短として電気抵抗を大幅に低減できる。これに対し図１４に示す従来の電池間接続構造では、皿状の接続体３における最も距離の長い平面部７と円筒部４とを隣接する２個の単電池Ｂ１，Ｂ２に接続しているので、両単電池Ｂ１，Ｂ２間の電流経路の距離が長くなって電気抵抗が高くなる。
【００６５】
しかも、上記電池間接続構造では、接続板３８が、３層構造のクラッド材によって形成されているので、中央のＣｕ層によって良好な導電性を確保しながらも、両面のＮｉ層を電池ケース１４の一般的な素材であるニッケルめっき鋼板に対し好適に溶接できるから、電気抵抗を一層低減できる。上述により、上記電池間接続構造は、接続板３８での電力損失を最小限に抑えることができる。
【００６６】
また、上記電池間接続構造では、ゴム弁体２２を保持する金属キャップ２１に対し側方で、且つ上方に離れた位置に突出するリング状の接続電極部２８の外側面と接続板３８の突起４２の対向箇所とにそれぞれ溶接電極を接触させてプロジェクション溶接を行うので、金属キャップ２１には全く電流が流れなく、金属キャップ２１の熱影響によってゴム弁体２２に変形が生じるおそれがない。これにより、この電池間接続構造では、ゴム弁体２２の所要の弁作動を常に確保することができる。これに対し図１４の従来の構造では、接続体３の突起９の対向箇所と金属キャップ１とにそれぞれ溶接電極を接触させてプロジェクション溶接を行わなければならないので、電流が流れる金属キャップ１が熱影響で内方に凹んでゴム弁体２２を変形させていた。
【００６７】
さらに、上記電池間接続構造では、単電池１３の底面に内方へむけ凹んだ凹部２９を設けていることにより、図３（ｃ）に示すように、負極集電体４３と電池ケース１４の底面部との間に僅かな隙間ｂを設けることができるから、電池ケース１４の底面部と接続板３８とをプロジェクション溶接するときに上記底面部が熱影響によって内方に膨出する状態に変形しても、この変形する底面部が負極集電体４３や極板群１７に対し悪影響を及ぼすことがない。したがって、上記電池間接続構造では、所要の電池容量と安定した電池機能とを確保することができる。これに対し従来の電池間接続構造、特に上述の第３の従来技術のように単電池を接続体を介さずに直接接続する構造では、負極集電体や極板群が、プロジェクション溶接時に内方に膨出する電池ケースの底面部から圧力を受けて変形していた。
【００６８】
なお、接続板３８は、後述する電池モジュールを構成した際に単電池１３の周囲に均等で、且つ大きな断面積の通風路を確保する目的で、中央部がくびれた平面視で瓢箪形状としているが、幅の狭い連結部４１での電気抵抗の増大を補助片２５によって抑制できるとともに、補助片２５によって接続板３８自体の機械的強度が向上する。
【００６９】
上記電池間接続構造は、図５（ｂ）に示す製作完了状態の電池モジュール１２を製作する過程において、図５（ａ）に示すように、両ケース半体３０Ａ，３０Ｂの各々の電池収納部３１内にそれぞれ単電池１３を挿入した状態で両ケース半体３０Ａ，３０Ｂを相互に突き合わせて、両ケース半体３０Ａ，３０Ｂの互いに対向する合計６組の連結部材３４に固定ねじ１６を螺合締結することにより、両ケース半体３０Ａ，３０Ｂが相互に固定されて、ホルダーケース３０が組み立てられる。図４は、図５（ａ）に示すように、２０個の単電池１３を収納してホルダーケース３０を組み立てたのちに、隣接する各２個の単電池１３を接続板３８で相互に接続した状態を示し、（ａ）は一部の平面図、（ｂ）は（ａ）のＣ−Ｃ線断面図、（ｃ）は（ａ）のＤ−Ｄ線断面図である。
【００７０】
図４において、両ケース半体３０Ａ，３０Ｂの電池収納部３１は、図の上下方向に長い平面視長方形の形状を有するとともに、その長方形の長手方向の対向隔壁の内面中央部から支持リブ５５がそれぞれ一体に突設されている。この両支持リブ５５は、各々の先端間の距離が単電池１３の電池ケース１４の外径とほぼ同一に設定されて、単電池１３に対しこれの外面における径方向の両側箇所に当接して支持している。電池ケース１４の外面における両支持リブ５５との接触箇所に対しそれぞれ９０°離間した２箇所は、電池収納部３１の隔壁に接触している。
【００７１】
また、支持リブ５５の外方端と、支持リブ５５が未形成の２つの隔壁のうちの接続板３８が対向されない側の１つの隔壁の開口縁とからは、内方に突出して電池ケース１４の電池軸方向の両側端面に当接する保持突部５６がそれぞれ一体形成されている。両ケース半体３０Ａ，３０Ｂの対向する保持突部５６間の距離は、単電池１３における接続電極部２８を除く電池ケース１４の両端面間の高さに等しくなるよう設定されているが、この単電池１３の高さのばらつきは、弾性体シート３６の弾性変形によって吸収される。
【００７２】
したがって、電池収納部３１内に収納された単電池１３は、電池ケース１４の外面における９０°の等間隔の４箇所が一対の支持リブ５５と２箇所の隔壁とにそれぞれ接触して、水平方向への動きを阻止され、且つ上端面と下端面とにそれぞれ当接する各３つの保持突部５６によって上下方向への動きを阻止されて、電池収納部３１内にがたつきなく保持されている。
【００７３】
各単電池１３は、従来構造のような接続体や絶縁リングのような側方に出っ張るものが装着されずに、そのまま電池収納部３１内に挿入されて、外面における９０°の等間隔の４箇所が一対の支持リブ５５と隔壁の２箇所とに接触して、水平方向への動きを阻止され、且つ上端面と下端面とにそれぞれ当接する各３つの保持突部５６によって上下方向への動きを阻止されることにより、振動や衝撃を受けた場合にもがたつきなく確実に保持される。
【００７４】
また、電池収納部３１内に挿入された単電池１３を接続板３８で接続した状態では、図４（ａ）に横平行線で明示するように、単電池１３の外周面と電池収納部３１の４つの隔壁との間の４箇所に、電池収納部３１内を貫通する空隙４４がそれぞれ生じる。これらの空隙４４は、電池モジュール１２が機能したときに単電池１３の効果的な放熱空間となる。
【００７５】
すなわち、上記４つの空隙４４は、電池ケース１４の外面を電池収納部３１の４つの隔壁に接触させる場合に比較して、支持リブ５５の突出長分だけ容積が拡大されて、空隙４４内を流通する風量が増大するとともに、接続板３８をこれの中央部に連結部４１を設けてくびれた形状として２つの単電池１３間の空隙を塞がないことにより、単なる長方形状とした接続板を設ける場合に比較して、４つの空隙４４がほぼ同様の断面形状としていることにより、単電池１３の外周全体に対し均等に冷却効果を作用させることができるから、単電池１３を一層効果的に冷却することができる。さらに、ホルダーケース３０の上下に設けられた補助片２５の収納空間４７は、４つの空隙４４を互いに連通させるので、この点からも単電池１３の冷却効果がさらに向上する。
【００７６】
つぎに、図１に戻って、電池モジュール１２の説明を続ける。上述したように、両ケース半体３０Ａ，３０Ｂが各々の電池収納部３１内に単電池１３が挿入された状態で互いに合体されてホルダーケース３０が組み立てられたのち、隣接する各２個の単電池１３が接続板３８で接続されて電池間接続構造が構成される。そののちに、そのホルダーケース３０の上面側および下面側の各開口部は、合成樹脂製の上蓋５３および下蓋５４を嵌入して施蓋されて、この上蓋５３および下蓋５４とホルダーケース３０の開口周縁部とを超音波溶着することによって封止される。上蓋５３および下蓋５４には、単電池１３とホルダーケース３０の電池収納部３１の４つの隔壁との間に形成された空隙４４にそれぞれ対応する形状の放熱用孔５７が、空隙４４に対向する各位置にそれぞれ形成されている。
【００７７】
つぎに、上記電池モジュール１２の組立手順について説明する。各構成要素が図１のように配置された状態において、先ず、下部ケース半体３０Ｂの各電池収納部３１には、２０個の単電池１３が上方の開口部から挿入される。このとき、単電池１３は、底面部が保持突部５６によって電池収納部３１の下方に抜脱することなく支持される。
【００７８】
続いて、弾性体シート３６が、下部ケース半体３０Ｂの上端開口縁部に貼着などの手段で装着される。そののち、上部ケース半体３０Ａが、下部ケース半体３０Ｂの上方に突出している単電池１３の上半部を各電池収納部３１内に下方から挿入させた状態で、図５（ａ）に示すように、弾性体シート３６を介して下部ケース半体３０Ｂに突き合わされる。これにより、両ケース半体３０Ａ，３０Ｂの各連結部材３４が上下で対向し、この上下各２つの連結部材３４に固定ねじ１６をねじ込み締結することにより、ホルダーケース３０が組み立てられる。このとき、単電池１３の高さの多少のばらきつは、弾性体シート３６の弾性変形によって吸収される。
【００７９】
このホルダーケース３０の電池収納部３１内に収納された各単電池１３は、上下の保持突部５６によって電池収納部３１から抜脱することのない状態に保持される。この状態において、ホルダーケース３０の上面側において、隣接する各２個の単電池１３間に接続板３８を架け渡して溶接することにより、上述した電池間接続構造を構成して、隣接する各２個の単電池１３を相互に接続する。このとき、図の左端の２個の単電池１３も接続板３８によって外部接続用正極端子３２および外部接続用負極端子３３に接続する。続いて、ホルダーケース３０の上端開口部に上蓋５３を嵌入したのち、上蓋５３の周端部とホルダーケース３０の上端開口周縁部とを超音波溶着して、ホルダーケース３０の上端開口部を封止する。
【００８０】
つぎに、上端開口を上蓋５３で施蓋したホルダーケース３０を上下反転させて、隣接する各２個の単電池１３間に接続板３８を架け渡して溶接することにより、上述した電池間接続構造を構成して、隣接する各２個の単電池１３を相互に接続する。これにより、２０個の単電池１３は、電気的に互いに直列接続され、且つ機械的に連結された状態でホルダーケース３０内に固定される。続いて、ホルダーケース３０の開口部に下蓋５４を嵌入し、その下蓋５４の周端部とホルダーケース３０の開口周縁部とを超音波溶着して、ホルダーケース３０の下端開口を封止すると、図５（ｂ）に示す電池モジュール１２が出来上がる。
【００８１】
なお、上蓋５３および下蓋５４とホルダーケース３０との固着手段としては、上記実施の形態で説明した超音波溶着に限らず、例えば、固定ねじを用いてもよい。
【００８２】
上述のようにして組み立てられた電池モジュール１２は、図３の電池間接続構造において説明したと同様の効果を得られるのに加えて、図１５に示すような複数個の単電池Ｂ１〜Ｂ６を電池軸方向に一列に配列して連結する不安定な従来の電池モジュールとは異なり、各単電池１３を振動や衝撃から保護できる状態に確実に保持できる。
【００８３】
すなわち、上記電池モジュール１２は、各単電池１３が各々の電池軸が平行となる配置でホルダーケース３０の個々の電池収納部３１内に収納され、且つ各単電池１３が電池収納部３１内において対向する一対の支持リブ５５と電池収納部３１の対向隔壁との４箇所に電池ケース１４の外面が接触して電池軸方向に対し直交方向にがたつきなく保持された状態で収納されていることと、単電池１３が電池軸方向の両端面に３つずつの保持突部５６が直接当接して電池軸方向にがたつきなく保持されていることと、両ケース半体３０Ａ，３０Ｂの間に介在されている弾性体シート３６によって単電池１３の電池軸方向に外部から加わる衝撃や振動が吸収されて各単電池１３に直接作用しないことにより、比較的多数個の単電池１３を収納しながらも、各単電池１３は、電池モジュール１２を電気自動車や電動自転車あるいは電動工具などの過酷な振動や衝撃が加わり易い環境下に装着した場合においても、保護された状態で確実に保持され、破壊などが生じるおそれがない。
【００８４】
また、平面視長方形の電池収納部３１の４つの角部において、単電池１３と電池収納部３１の隔壁との間に互いにほぼ同じ容積を有し、且つ比較的大きな断面積に形成された空隙４４は、上，下蓋５３，５４の各々の放熱用孔５７を通じて電池モジュール１２の上下両面側の外部にそれぞれ連通している。これにより、ホルダーケース３０の一面側から各単電池１３の各々の周囲をそれぞれ通って他面側に貫通する放熱用通路が形成されるから、各単電池１３は、放熱用通路内を流通する風によって極めて効果的に冷却され、しかも、比較的多数個の単電池１３の全てが均等に冷却される。そのため、この電池モジュール１２を多数個用いて構成する電池パックでは、従来の電池パックに備えられている冷却フィンブレードなどの冷却機構が不要となる。この電池パックについての詳細は後述する。
【００８５】
さらに、上記電池モジュール１２では、各単電池１３が個々の電池収納部３１の４辺の隔壁で囲まれて収納されることにより、各単電池１３間が完全に電気絶縁された状態に保持されるので、従来の電池モジュールにおいて各単電池Ｂ１〜Ｂ６間を絶縁するために用いられていた絶縁リング１１や直列接続した各単電池Ｂ１〜Ｂ６の外周面を被覆する塩化ビニールなどの電気絶縁性および熱シュリンク性を有する樹脂製の外装チューブなどが不要となり、材料コストの低減と生産性の向上とを図ることができる。
【００８６】
また、従来の電池モジュールでは、電池軸方向に直列接続する各単電池Ｂ１〜Ｂ６の側方に接続体３や絶縁リング１１などが出っ張ることから、外形、長さおよび平行度を高精度に製作するのが困難であるのに対し、上記電池モジュールでは、合成樹脂製のホルダーケース３０の成形精度によって外形寸法が一義的に決定されて、組立工程を経たのちに寸法ばらつきなどが生じることがなく、形状的に高精度なものとなる。
【００８７】
さらに、上記電池モジュール１２は、製作過程において、両ケース半体３０Ａ，３０Ｂをこれらの電池収納部３１内に所要個数の単電池１３を収納した状態で互いに合体してホルダーケース３０を組み立てたときに、各単電池１３がホルダーケース３０内に抜脱不能、且つがたつきの無い状態に固定されるから、その後に接続板３８を隣接する各２個の単電池１３間に架け渡して行う溶接作業が一層容易となり、接合不良が生じるおそれが殆どなくなる。
【００８８】
さらにまた、上記電池モジュール１２は、上述したように比較的多数個（実施の形態では２０個）の単電池１３がホルダーケース３０内に封入されて堅牢な構造で保持されているとともに、ホルダーケース３０の外部にインサート成形されたナットからなる連結部材３４を一体に備えているので、６個の個数の単電池Ｂ１〜Ｂ６を単に電池軸方向に直列接続しただけの従来の電池モジュールとは異なり、そのままで電動自転車や電動工具などの駆動電源として用いることも可能である。特に、上記電池モジュール１２は、電気自動車のモータ駆動電源などに用いることを目的として、これを多数本連結して電池パックとしたときに、一層顕著な効果を得られるものである。つぎに、上記電池モジュール１２を用いて構成した電池パックについて説明する。
【００８９】
図６は、上記電池モジュール１２を６本用いて、合計１２０本の単電池１３を直列接続する電池パックを製作する過程の相対配置を示す斜視図である。この電池パックは、３本の電池モジュール１２を平行に配置して互いに近接させた状態に並置し、これら３本の各電池モジュール１２の各々の上面に、他の３本の電池モジュール１２をそれぞれ上下反転させた配置で重ね合わせる。このとき、上下各２本の電池モジュール１２間では、互いに反転した配置で突き合わされることにより、各々の両側辺に各５個ずつで計１０個の連結部材３４が互いに近接して対向する。この互いに近接対向する１０組の連結部材３４には、それぞれ固定ねじ（図示せず）が螺合締結される。これにより、図８に示すように、各２本の電池モジュール１２が重ね合わせ状態で相互に連結された電池モジュールユニット４８が３組出来上がる。
【００９０】
上記電池モジュールユニット４８における上下各２本の電池モジュール１２間では、互いに接触する上蓋５３と下蓋５４との対応する放熱用孔５７が相互に合致して連通する。これにより、各電池モジュールユニット４８における上下各２本の電池モジュール１２間では、個々の単電池１３の周囲を通って一面側から他面側に貫通する放熱用通路が形成されるので、上下各２本の電池モジュール１２を連結した電池モジュールユニット４８においても、個々の単電池１３の冷却機能が確実に確保される。
【００９１】
図７は、３組の電池モジュールユニット４８を用いて電池パックを構成する製作過程を示す斜視図、図８は、その３組の電池モジュールユニット４８を用いて構成した本発明の一実施の形態に係る電池パック４９を図７のＰ方向から見た矢視図である。但し、同図は、後述するバスパー５１を除外してＰ方向から見た矢視図である。この電池パック４９は、３組の電池モジュールユニット４８を、上下一対の外装プレート５０と、この一対の外装プレート５０の前端部および後端部（図７の左端部および右端部）に取り付けられて計１２０個の単電池１３を直列接続また並列接続するように各電池モジュール１２の外部接続用正極端子３２および外部接続用負極端子３３並びに電極取り出し部３７に導出された接続板３８を相互に電気的接続する一対のバスパー（図７に図示）５１とを用いて一体化することにより構成されている。
【００９２】
一対の外装プレート５０は、３組の電池モジュールユニット４８の上下方向に貫通する上述の放熱用通路に連通する放熱用空間を形成する溝状の凹所５２が長手方向に沿って屈曲形成されている。この各凹所５２の各間には、隣接する２組の電池モジュールユニット４８の各々の各取付部材４５が支持される二つの取付面５８が設けられ、また、外装プレート５０の両端近傍箇所には、両側に位置する各電池モジュールユニット４８の各取付部材４５がそれぞれ支持される二つの取付面５９が設けられている。さらに、外装プレート５０には、その両側部を取付面５９に対し直交方向に屈曲して、一対の連結片６０が形成されている。上記取付面５８，５９および連結片６０には、所定箇所に取付孔６１が形成されている。
【００９３】
つぎに、上記電池パック４９の組立手順について説明する。３組の電池モジュールユニット４８は、下方の外装プレート５０に対して、取付面５８，５９の各取付孔６１に各取付部材４５が合致する位置決め状態で、隣接する二つの取付面５８，５９に架け渡す配置で載置するとともに、その３組の電池モジュールユニット４８には、上方の外装プレート５０を、取付面５８，５９の各取付孔６１に各取付部材４５が合致する位置決め状態で被せる。
【００９４】
つぎに、固定ねじ６２を、上方の外装プレート５０の各取付孔６１から、電池モジュールユニット４８の二つの電池モジュール１２の上下で合致されている各２つの取付部材４５および下方の外装プレート５０の取付孔６１に挿通させたのち、図８のナット６３に螺合締結することにより、各電池モジュールユニット４８は上下一対の外装プレート５０に両側から挟まれる状態に取り付けられる。この上下一対の外装プレート５０の各々の両側の連結片６０は、図８に示すように、各々の先端部を重ね合わせた状態で固定ねじ６４で相互に連結される。最後に、一対のバスパー５１を上下の外装プレート５０の両端部に所定の取付手段（図示せず）で取り付けることにより、電池パック４９が出来上がる。
【００９５】
上記電池パック４９は、一対の電池モジュール１２を固定ねじ１６で螺合締結する簡単な固定手段で容易に連結してブロック形態の電池モジュールユニット４８を構成することができるとともに、複数の電池モジュールユニット４８を、これの回りに一対の外装プレート５０と一対のバスパー５１を囲むように配置して固定ねじ６２を螺合締結するだけの簡単な固定手段で容易に一体化して構成できる。このように堅牢な構造に容易に組み立てできるのは、電池モジュール１２がホルダーケース３０の成形精度で一義的に決定される極めて高精度な外形を有する直方体に構成されていることと、比較的多数個の単電池１３がホルダーケース３０内に振動や衝撃を直接受けない状態に収納保持されていることによって可能になっている。そのため、この電池パック４９は極めて高い生産性で製造することができる。
【００９６】
これに対し、上述の第４の従来技術の電池パックでは、電池モジュールが複数個の単電池を電池軸方向に一列に並べて接続体や絶縁リングを介して相互に連結しただけの不安定な構成であるため、その複数個の電池モジュールを、複雑な形状のホルダーケースの両端壁や中間壁の貫通孔に挿通して一列多段の配置で収納するのに手間がかかり、しかも、一列配置の単電池の外周面側に接続体や絶縁リングなどが出っ張っている電池モジュールを貫通孔に挿入して保持するので、電池モジュールを隙間無く保持するのが困難であり、振動や衝撃を受けたときに単電池がホルダーケース内でがたついて破損するおそれがある。
【００９７】
また、上述の第５の従来技術の電池パックにおいても、上記と同様の構成となった多数本の電池モジュールを、ホルダーケースにおける蓋ケースと中間ケースの各々の内面に突設したホルダーリブによって保持するので、上述と同様の欠点がある。上記電池パック４９は、上述の従来の種々の欠点を一挙に解消できるものである。
【００９８】
また、上記電池パック４９は、電池モジュール１２並びに電池モジュールユニット４８が、各単電池１３の周囲に対し上下に貫通した放熱用通路を有しているのに加えて、図８に示すように、上下の外装プレート５０の凹所５２の存在によって、各電池モジュールユニット４８と各外装プレート５０との各間には、図の水平方向に延びる放熱用通路６７がそれぞれ形成されているとともに、隣接する２つの電池モジュールユニット４８の各間および両側の電池モジュールユニット４８と連結片６０との間には、一対の外装プレート５０の取付面５８，５９の存在によって放熱用通路６８が形成され、さらに、バスパー５１の外側を覆う補助プレート（図示せず）には、スリット状の通風孔６９が形成されている。したがって、この電池パック４９では、１２０個もの多数個の単電池１３を極めて効率的に、且つ全てを均等に冷却することができる。これに対し、従来の電池パックでは、単電池の温度を検出する温度センサと、この温度センサの検出温度に基づき作動させる送風機を設けているので、構成が大型化するとともに、かなりのコスト高となる。
【００９９】
さらに、この電池パック４９は、電池モジュール１２が多数個の単電池１３を安定に保持したブロック形態となっていることから、電池モジュール１２の個数を変更する場合に、外装プレート５０およびバスパー５１の形状を変更するだけでよく、外装プレート５０は、単なる板材を屈曲して形成したものであるから、形状の異なるものを極めて安価に製作して対応できる。これに対し、従来の電池パックでは、極めて複雑な形状を有するホルダーケースを変更しなければならず、そのホルダーケースの金型を新たに製作するのに相当の費用を要してかなりのコスト高となる。
【０１００】
図９は本発明の他の実施の形態に係る電池間接続構造に用いる一対の接続板７０を示し、（ａ）は斜視図、（ｂ）は平面図、（ｃ）は接続板７０を用いて構成した電池間接続構造を示す平面図である。この一対の接続板７０は、隣接する２個の単電池１３間に架け渡す長さを有する平板状であって、単電池１３のリング状の接続電極部２８のほぼ半部に対応する形状を有して長手方向の両側部分に設けられた一対の接続部７１と、この両接続部７１を相互に連結する直線状の連結部７２とを一体に有している。各接続部７１には、２個ずつのプロジェクション溶接用突起７３が形成されている。さらに、接続板７０の外側辺には、連結部７２から両側の接続部７１の各半部に延びる補助片２５が屈曲形成されている。なお、この接続板７０は、一実施の形態と同様に、Ｎｉ−Ｃｕ−Ｎｉの三層のクラッド材によって形成されている。
【０１０１】
上記一対の接続板７０は、（ｃ）に示すように、所定の間隙ａを存して互いに近接対向させた配置で隣接する２個の単電池１３間に架け渡されて、各突起７３を介してプロジェクション溶接されることにより、突起７３が溶融したナゲット部分で一方の単電池１３の接続電極部２８と他方の単電池１３の底面部とに溶着される。一対の接続板７０の間隙ａは、一実施の形態の接続板３８のスリット４０の幅とほぼ同じに設定される。
【０１０２】
したがって、この電池間接続構造は、２個の単電池１３を接続するのに接続板７０を一対必要とするが、その接続板７０は、一実施の形態の接続板３８のような透孔３９やスリット４０を設けることなく、打ち抜き加工ののちに曲げ加工を行うだけで得られる単純な形状であるから、安価に大量生産することができ、一実施の形態の電池間接続構造に比較して殆どコスト高にならない。しかも、この電池間接続構造は、一実施の形態の電池間接続構造と同様の効果を得られるのに加えて、別部材の一対の接続板７０を離間して組み合わせるので、プロジェクション溶接時の無効分流を完全に無くすことができる大きな利点がある。
【０１０３】
図１０は、本発明のさらに他の実施の形態に係る電池間接続構造を示し、（ａ）は分解斜視図、（ｂ）は斜視図である。この電池間接続構造に用いる接続板７４は、Ｎｉ−Ｃｕ−Ｎｉの三層のクラッド材からなる平板状であって、一実施の形態に用いた接続板３８と同様の透孔３９、一対のスリット４０および４個のプロジェクション溶接用突起４２を有する一対の接続部３５と、この両接続部３５を相互に連結する連結部４１とを一体に有しており、上記接続板３８と相違する点は、一方（図の左方）の接続部３５における連結部４１の半部両側に、電池ケース１４の外径とほぼ同じ径の大径部７５が側方に延設されているとともに、両側辺が直交方向に延びる一対の補助片７６が、突起４２と同一方向に向けた配置に形成されていることだけである。
【０１０４】
この電池間接続構造では、一実施の形態と同様の効果を得られるのに加えて、（ｂ）に明示するように、接続板７４が、一対の補助片７６の一方側（図の左方側）が電池ケース１４の外面に沿って接触し、且つ補助片７６の他方側（図の右方側）が接続電極部２８の外面に沿って接触する配置で隣接する２個の単電池１３間に架け渡されて、両単電池１３に対し仮止め状態に固定されるから、次工程のプロジェクション溶接を容易、且つ正確に行うことができるとともに、接続板７４による２個の単電池１３の連結構造の機械的強度が一層向上する利点がある。
【０１０５】
図１１（ａ）は本発明のさらに他の実施の形態に係る電池間接続構造を示す平面図、（ｂ）は（ａ）のＥ−Ｅ線断面図である。この実施の形態では、上記各実施の形態でのプロジェクション溶接に代えて、隣接する各２個の単電池１３に接続板７７をレーザー溶接またはビーム溶接を行って接続するものである。この接続板７７は、Ｎｉ−Ｃｕ−Ｎｉの三層のクラッド材からなる平板状であって、一実施の形態に用いた接続板３８と同様の透孔３９を有する一対の接続部３５と、この両接続部３５を相互に連結する連結部４１とを一体に有しているとともに、上記接続板３８と同一形状の補助辺２５が両側辺にそれぞれ屈曲形成されており、上記接続板３８と相違する点は、一対の接続部３５に、透孔３９と同心円の円弧状となった二つの絞り薄肉部７８が、各々の中央部が両透孔３９の中心を結ぶ線上に位置する配置で形成されているのみである。
【０１０６】
この電池間接続構造では、上記接続板７７を一方の単電池１３の接続電極部２８と他方の単電池１３の底面部とに架け渡して載置した状態において、（ｂ）に示すように、各絞り薄肉部７８にレーザー光線またはビーム光線などの光線７９を照射して、絞り薄肉部７８を接続電極部２８および底面部にそれぞれ溶着することにより、接続板７７を介して２個の単電池１３を相互に接続した構成になっている。
【０１０７】
この電池間接続構造は、上述した各実施の形態の電池間接続構造と同様に、隣接する２個の単電池１３間の電流経路の距離Ｌを最短として電気抵抗を大幅に低減できる他に、各実施の形態の電池間接続構造とほぼ同様の効果を得ることができる。また、レーザー溶接またはビーム溶接は、絞り薄肉部７８に光線７９を照射して行うので、絞り薄肉部７８が接続電極部２８および電池ケース１４よりも先に溶融することによって円弧状の溶接箇所に十分な熱が効果的に与えられるから、所要の溶接強度を確保することができ、溶接の信頼性が向上する。なお、この電池間接続構造では、絞り薄肉部７８に代えて、同様の円弧状のスリットを設けて、このスリットに光線７９を照射してレーザー溶接またはビーム溶接してもよく、さらには、抵抗溶接で接続板７７を両単電池１３に接続してもよい。
【０１０８】
図１２および図１３は本発明のさらに他の実施の形態に係る電池モジュール８０を示し、図１２は電池モジュール８０の各構成要素の相対配置を示した分解斜視図、図１３（ａ）は電池モジュール８０の製作過程を示す斜視図、同図（ｂ）は組立完了状態の電池モジュール８０を示す斜視図である。図１の一実施の形態の電池モジュール１２では、１０個の単電池１３を一列配置した電池列を２列に並置して計２０個の単電池１３を収納する場合を例示したのに対し、この実施の形態での電池モジュール８０では、１０個の単電池１３を一列に配列して収納する構成になっている。
【０１０９】
この電池モジュール８０は、一実施の形態の電池モジュール１２を単電池１３の配列方向に沿って２分割した構成とほぼ同等の構成を有しているので、上記電池モジュール１２に相当するものには同一の符号を付して、重複する説明を省略し、以下に、上記電池モジュール１２と相違する点についてのみ説明する。
【０１１０】
単電池１３は上述の各実施の形態で説明したものと同様である。ホルダーケース８１は、上部ケース半体８１Ａと下部ケース半体８１Ｂとを合体して構成され、両ケース半体８１Ａ，８１Ｂは１０個の電池収納部３１が一列に配設されており、それに伴って上部ケース半体８１Ａには、外部接続用正極端子３２および外部接続負極端子３３が両端部に形成されている。接続板３８は一実施の形態と同一のものである。弾性体シート８２は、一実施の形態で用いた弾性体シート３６を長手方向に沿って２分割したと同等の平面視長方形の形状になっている。上蓋８３および下蓋８４は、一実施の形態の上蓋５３および下蓋５４を長手方向に沿って２分割したと同等の平面視長方形の形状になっており、ホルダーケース８１の各電池収納部３１の隔壁と単電池１３との空隙に対応する形状の放熱用孔５７が上記空隙に対応する箇所に形成されている。
【０１１１】
上記電池モジュール８０は、一実施の形態の電池モジュール１２で説明したと同様の組立手順で図１３（ｂ）に示すような形状に組み立てられる。この電池モジュール８０は、一実施の形態の電池モジュール１２に比較して、出力電圧が半分になるだけで、ほぼ同様の構成を有していることから、同様の効果を得ることができる。用途としては、連結部材３４を介して２本の電池モジュール８０を相互に連結して電池モジュールユニットを構成したのち、この電池モジュールユニットを所要個数連結することにより、例えば、電気自動車よりも低い駆動電力の電動自転車や電動工具などの駆動電源として用いれば、振動や衝撃に対し強いことから、好適なものとなる。
【０１１２】
【発明の効果】
以上のように、本発明の電池間接続構造によれば、単なる平板状である接続板の両側部を、各々の電池軸が平行となる配置で並置された２個の単電池のうちの一方の単電池のリング状の接続電極部と他方の単電池の電池ケースの底面とに架け渡して支持された安定姿勢で溶接を行えるので、接合不良といった不具合が生じるおそれがなく、歩留りが大幅に向上する。また、接続部と接続電極部の間および接続部と電池ケースの底面の間とをそれぞれ接合するための溶接を合計２回行えばよく、溶接回数が大幅に削減されて生産性が格段に向上する。さらに、単電池をこれらの電池軸に平行とした配置で並置したことにより、２個の単電池間における電流経路は、一方の単電池のリング状の接続電極部と他方の単電池の底面の外周部分との互いに近接した箇所とを結ぶ最短距離となり、電気抵抗を大幅に低減できる。また、隣接する各２個の単電池間に架け渡す接続板は、隣接する２個の単電池全体の外形に対応するほぼ瓢箪形状であって、２個の単電池間の隙間を塞がないので、この電極間接続構造を電池モジュールの構成した場合には、各単電池の周囲に均等な断面積を有して電池軸方向に沿った放熱用通路を効果的に構成できる。また、接続板の連結部は、小さな幅に形成されているが、両側辺に設けた補助片によって電気抵抗が高くなるのを抑制される。しかも、接続板は、補助片によって機械的強度が向上する利点がある。
【０１１３】
また、本発明の電池モジュールによれば、ホルダーケースが所要個数の単電池を収納したブロック形態となるから、次工程での各２個の単電池間への接続板の溶接作業が極めて容易となり、生産性が格段に向上する。また、合成樹脂製のホルダケースの成形精度によって外形寸法が一義的に決定されるから、寸法ばらつきが生じることがなく、形状的に高精度なものとなる。さらに、絶縁リングや樹脂製外装チューブが不要となり、材料コストの低減と生産性の向上とを図ることができる。また、接続板を２個の単電池全体の外形に対応する形状としたので、単電池の周囲に均等な断面積の空隙を形成でき、多数個の単電池であっても、これらを均等、且つ効果的に冷却することができる。
【０１１４】
また、本発明の電池パックによれば、電池モジュール同士を固定部材による簡単な固定手段で容易に連結して電池モジュールユニットを構成することができ、この電池モジュールユニットを２枚の外装プレートに固定部材で固定するだけで、非常に堅牢な構造に容易に組み立てでき、極めて高い生産性で製造できる。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る電池モジュールの各構成要素の相対配置を示した分解斜視図。
【図２】（ａ）は同上の電池モジュールの構成要素である単電池を示す斜視図、（ｂ）は（ａ）のＡ−Ａ線断面図。
【図３】同上の電池モジュールにおける単電池の接続に適用した本発明の一実施の形態に係る電池間接続構造を示し、（ａ）は平面図、（ｂ）は正面図、（ｃ）は（ａ）のＢ−Ｂ線で切断した拡大断面図。
【図４】（ａ）は同上の電池モジュールの製作過程におけるホルダーケースの電池収納部内に挿入した単電池を接続板で接続した状態の一部の平面図、（ｂ）は（ａ）のＣ−Ｃ線断面図、（ｃ）は（ａ）のＤ−Ｄ線断面図。
【図５】（ａ）は同上の電池モジュールの製作過程におけるホルダーケース組立工程の概略斜視図、（ｂ）は製作完了状態の電池モジュールの斜視図。
【図６】同上の電池モジュールを６本用いて３組の電池モジュールユニットを構成する製作過程の相対配置を示す斜視図。
【図７】同上の３組の電池モジュールユニットを用いて電池パックを構成する製作過程を示す斜視図。
【図８】同上の３組の電池モジュールユニットを用いて構成した本発明の一実施の形態に係る電池パックにおける図７のＰ方向から見た矢視図。
【図９】本発明の他の実施の形態に係る電池間接続構造に用いる一対の接続板を示し、（ａ）は斜視図、（ｂ）は平面図、（ｃ）は接続板を用いて構成した電池間接続構造を示す平面図。
【図１０】本発明のさらに他の実施の形態に係る電池間接続構造を示し、（ａ）は分解斜視図、（ｂ）は斜視図
【図１１】（ａ）は本発明のさらに他の実施の形態に係る電池間接続構造を示す平面図、（ｂ）は（ａ）のＥ−Ｅ線断面図。
【図１２】本発明の他の実施の形態に係る電池モジュールの各構成要素の相対配置を示した分解斜視図。
【図１３】（ａ）は同上の電池モジュールの製作過程を示した概略斜視図、（ｂ）は製作完了状態の電池モジュールの斜視図。
【図１４】従来の電池間接続構造を示す縦断面図。
【図１５】同上の電池間接続構造を用いて構成した電池モジュールを示す斜視図。
【符号の説明】
１２電池モジュール
１３単電池
１４電池ケース
１６，６４固定ねじ（固定部材）
１８封口体
２５，７６補助片
２８接続電極部
２９凹部
３０，８１ホルダーケース
３０Ａ，３０Ｂ，８１Ａ，８１Ｂケース半体
３１電池収納部
３２外部接続用正極端子
３３外部接続用負極端子
３４連結部材
３５，７１接続部
３６弾性体シート
３８，７０，７４，７７接続板
４１，７２連結部
４４空隙
４５取付部材
４８電池モジュールユニット
４９電池パック
５０外装プレート
５１バスパー
５２凹所
５３，８３，上蓋（蓋部材）
５４，８４下蓋（蓋部材）
５５支持リブ
５６保持突部
５７放熱用孔
５８，５９取付面
７８絞り薄肉部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inter-battery connection structure for configuring a battery module capable of obtaining a required output voltage by connecting a plurality of single cells, a battery module configured using the inter-battery connection structure, and a plurality of the battery modules. The present invention relates to a battery pack configured by being individually connected, electrically connected, and mechanically coupled.
[0002]
[Prior art]
Conventionally, first to third conventional techniques described below have been known as an inter-battery connection structure for configuring a battery module that obtains a required output voltage by connecting a plurality of single cells in series. As shown in FIG. 14, the first prior art is provided with a metal cap 1 that serves as a positive electrode terminal of one battery B1 with a dish-like connection body 3 arranged between two batteries B1 and B2. Each of the sealing plate 10 and the battery case 2 serving as the negative electrode terminal of the other battery B2 is connected by projection welding (see, for example, Patent Document 1).
[0003]
The connection body 3 includes a cylindrical portion 4 that is externally fitted to the battery case 2, and a flat surface portion 7 that is in contact with the sealing plate 10, and an inner surface of the cylindrical portion 4 and a lower surface of the flat surface portion 7. Projection welding projections 8 and 9 are formed at respective positions at equal intervals of 90 ° on the same radius. By performing projection welding via the projections 8 and 9, the flat portion 7 of the connection body 3 is connected to the sealing plate 10 electrically connected to the metal cap 1 in one battery B1, and the cylindrical portion 4 is connected to the other side. To the battery case 2 of the battery B2. Between the battery case 2 and the connection body 3 of one battery B1 is prevented from being electrically short-circuited by the insulating ring 11. Thus, the batteries B1 and B2 are electrically connected in series and mechanically connected to each other.
[0004]
FIG. 15 shows a conventional battery module 5. The battery module 5 includes two cells B1 to B6, which are necessary for obtaining a required output voltage (six examples are shown in the figure), between two adjacent cells shown in FIG. It is comprised by connecting in series with a connection structure.
[0005]
The second prior art has substantially the same configuration as the first prior art. The difference from the first prior art is that the second prior art has a dish shape substantially the same as the connection body 3 of the first prior art. A pressure contact convex portion is provided on each of the central connection portion (plane portion) and the flange portion (cylindrical portion) of the connection body, and the dish-like connection body is connected to two single cells by laser welding via the pressure contact protrusion portion. It is only a structure (for example, refer patent document 2).
[0006]
Furthermore, the third conventional technique directly connects a plurality of batteries without using a connection body as in the first and second conventional techniques (see, for example, Patent Document 3). That is, a connection electrode portion protruding outward from the battery shaft is formed in a sealing body that closes the opening of the battery case, and a plurality of the connection electrode portions of one of the two adjacent cells are provided on the connection electrode portion. A plurality of single cells are arranged in a row in the direction of the battery axis by directly connecting to the bottom surface of the other unit cell opposite to the opening of the battery case via a projection welding projection. Are connected in series.
[0007]
A battery module configured by using any one of the first to third prior art inter-battery connection structures is configured as a battery pack in which a large number of modules are electrically connected in series to extract high-voltage power. A battery pack capable of obtaining such high voltage power is used, for example, as a drive power source for the motor of a hybrid type electric vehicle using a combination of an internal combustion engine and a battery drive motor as a travel source. As this type of conventional battery pack, those disclosed in the fourth and fifth prior arts described below are known.
[0008]
The battery pack according to the fourth prior art has a configuration in which battery modules 5 as shown in FIG. 15 are arranged in multiple rows and multiple stages in a plastic holder case having a rectangular box shape with an open top. (For example, see Patent Document 4). The holder case has a circular through-hole for inserting the battery module 5 whose outer diameter is an elongated cylindrical shape formed in both end walls as many as the number of battery modules accommodated, and stably holds the battery module. An intermediate wall for this purpose is provided between the both end walls in parallel therewith, and the same number of circular through holes as the both end walls are opened in this intermediate wall. The battery module is inserted into the through-holes of both end walls and the intermediate wall and held at a fixed position of the holder case.
[0009]
The battery pack according to the fifth prior art includes a holder case for holding a plurality of battery modules inside in a parallel arrangement, and the holder case includes a lid case disposed on both sides, and the both lid cases (See, for example, Patent Document 5). The holder case is provided with holder ribs on both sides of the intermediate case and the inner surface of the lid case to hold the battery modules in multiple rows and stages, and connects the lid case and the intermediate case on both sides. Then, the battery modules in a plurality of rows and a plurality of stages are sandwiched from both sides by the holder rib and held in place.
[0010]
[Patent Document 1]
JP-A-10-106533
[0011]
[Patent Document 2]
JP 2000-126703 A
[0012]
[Patent Document 3]
JP 2000-149907 A
[0013]
[Patent Document 4]
JP-A-10-270006
[0014]
[Patent Document 5]
JP 2000-223096 A
[0015]
[Problems to be solved by the invention]
However, the battery module 5 configured using the inter-battery connection structure according to the first prior art has an elongated cylindrical outer shape in which a plurality of unit cells B1 to B6 are connected in the battery axial direction. It is extremely difficult to produce the entire outer shape, length and parallelism with high accuracy. In addition, since the projection welding must be performed in an unstable posture in which the projection welding projection 8 of the cylindrical portion 4 of the connection body 3 is in contact with the outer surface of the circular battery case 2, the yield of the battery module 5 is reduced. Is invited. In addition, the number of times of welding is such that when two adjacent ones of each of the cells B1 to B6 are connected by one connecting body 3, the battery case 2 and the connecting body 3 are four times in series welding. The connection body 3 and the sealing plate 10 are required to be twice in the series welding method, and the productivity is poor as the number of welding times increases. In addition, current flows between the two adjacent unit cells B1 to B6 through a path via the connection body 3, so that the current path becomes longer, and the electrical resistance increases by the length.
[0016]
Furthermore, since the connecting body 3 and the insulating ring 11 are mounted between every two adjacent unit cells B1 to B6, the component cost is increased, and the mounting process of the connecting body 3 and the insulating ring 11 is required. Productivity is further reduced. In addition, this battery module is often used in a vibrating environment such as an electric vehicle or an electric bicycle. However, in the connection structure of these cells B1 to B6, the bending strength between the cells B1 to B6 is high. Since it is low and the mechanical strength of the connection is insufficient, the connection body 3 is broken and the connection between the cells B1 to B6 is easily disconnected when subjected to severe vibration or impact.
[0017]
In addition, since the battery module configured using the inter-battery connection structure according to the second prior art has substantially the same configuration as that of the first prior art, the outer shape, the length, and the parallel as the battery module. It is difficult to manufacture with a very high degree of accuracy, and laser welding is performed in an unstable state, so the yield is low, the productivity is low as the number of welds increases, and connection bodies and insulating rings are required. As a result, the cost of parts increases and the productivity further decreases as the number of man-hours increases, and the connection body easily breaks when subjected to severe vibration and impact. Have the same disadvantages as the prior art. In addition, in this battery module, when a connection member having a large thickness is used so as not to be broken even when subjected to vibration, stress may be applied to the sealing member, which may impair the hermeticity of the sealing member. .
[0018]
Furthermore, the battery module configured using the inter-battery connection structure according to the third prior art does not require a connection body or an insulating ring, and the number of times of welding, compared to the battery modules of the first and second prior arts. However, this battery module has the advantage of reducing costs, but this battery module is inevitably mechanically strong when subjected to vibrations or side impacts because the cells are directly welded together. Since the bending strength is even lower than those of the first and second prior arts, when used in an environment subject to severe vibration such as an electric vehicle or an electric bicycle, It is necessary to accommodate in a robust holding form, and such a configuration results in an increase in cost.
[0019]
On the other hand, the conventional battery pack is configured by arranging and connecting any one of the battery modules according to the first to third prior arts as required, but in the battery pack according to the fourth prior art, The mold for the holder case that has through holes in both the end walls and the intermediate wall cannot be easily removed from the part that forms the above shape, so it has a complicated structure and takes time and labor to manufacture the holder case. Manufacturing costs are high. In addition, since the battery module has a configuration in which the connecting body 3 and the insulating ring 11 protrude outward from the battery case 2 at the inter-battery connection portion, and the outer diameter is not constant over the whole, each of the both end walls and the intermediate wall of the holder case Even if the through holes are formed with high accuracy, all the battery modules cannot be inserted and held in the through holes without any gaps, so that the battery modules cannot be stably held without rattling. In addition, the work of inserting and attaching the battery module into the small through-hole is very laborious, so the productivity is poor. Further, when the number of battery modules stored is changed, the holder case needs to be manufactured with a new molding die, which further increases the cost.
[0020]
Further, in the battery pack according to the fifth prior art, when any deformation such as warpage occurs in any of the lid case and the intermediate case constituting the holder case, all the battery modules are equally held. It becomes difficult. Therefore, the lid case and the intermediate case are required to be produced with high accuracy in the shape of the holder ribs and the dimensions between the holder ribs without causing deformation such as warping. I will.
[0021]
Therefore, the present invention has been made in view of the above-described conventional problems, and has a battery-to-battery connection structure that can reduce electric resistance while being configured inexpensively with an easy process, and is robust against vibration and impact. It is an object of the present invention to provide a battery module having such a configuration and a battery pack in which a large number of battery modules can be easily and surely connected to form a required configuration.
[0022]
[Means for Solving the Problems]
To achieve the above object, the inter-battery connection structure according to the present invention includes a bottomed cylindrical battery case that also serves as one electrode, and the other electrode that is closed in an electrically insulated state with respect to the opening of the battery case. A plurality of unit cells each having a ring-shaped connection electrode portion projecting outward in the battery axial direction at a location in the vicinity of the outer periphery of the sealing unit. Juxtaposed with parallel axes In addition, adjacent cells to be conductively connected are arranged so that their orientations are opposite. The flat connecting plate is placed in a state of being bridged between the connection electrode portion of one of the two adjacent unit cells and the bottom surface of the battery case of the other unit cell, The connection electrode portion and the bottom surface portion of the battery case are connected to each other by welding, and the connection plate has an arc shape that can include at least the connection electrode portion, and is welded to the unit cell. A pair of connecting portions and a connecting portion that has a substantially rectangular shape having a width smaller than the diameter of the arc shape and connects the pair of connecting portions to each other, and has a substantially bowl shape in plan view. And it is characterized by providing a pair of auxiliary piece which extends in the orthogonal direction from the both sides of the said connection part at least, respectively.
[0023]
In this inter-battery connection structure, the ring-shaped connection electrode of one unit cell of two unit cells juxtaposed on both sides of a connection plate that is a simple flat plate in such a manner that the cell axes are parallel to each other. Since welding can be performed in a stable posture supported across the bottom of the battery case and the battery case of the other unit cell, there is no risk of problems such as poor bonding, and the yield is greatly improved. Moreover, it is only necessary to perform a total of two weldings for joining the connection part and the connection electrode part and between the connection part and the bottom surface of the battery case, and the number of weldings is greatly reduced, and the productivity is remarkably improved. To do. Furthermore, by arranging the single cells in parallel with each other so as to be parallel to the battery axis, the current path between the two single cells is changed between the ring-shaped connection electrode portion of one single cell and the bottom surface of the other single cell. The shortest distance between the outer peripheral portion and a portion close to each other is obtained, and the electrical resistance can be greatly reduced.
[0024]
Further, the connecting plate that spans between each two adjacent unit cells has a substantially bowl shape corresponding to the entire outer shape of the two adjacent unit cells, and does not block the gap between the two unit cells. Therefore, when this inter-electrode connection structure is configured as a battery module, it is possible to effectively configure a heat dissipation passage along the battery axial direction having an equal cross-sectional area around each unit cell. Moreover, although the connection part of a connection board is formed in the small width | variety, it is suppressed that an electrical resistance becomes high with the auxiliary piece provided in the both sides. Moreover, the connection plate has an advantage that the mechanical strength is improved by the auxiliary piece.
[0025]
In the inter-battery connection structure according to the above invention, a concave portion recessed inward is formed at the center of the bottom surface portion of the battery case, and one connection portion of the connection plate is outside the concave portion in the bottom surface portion of the battery case. In addition, it is preferable to have a configuration in which the adjacent unit cells are welded to each other.
[0026]
According to this configuration, since the concave portion is formed, a slight gap can be provided between the bottom surface portion of the battery case and the negative electrode current collector, and thus the bottom surface portion of the battery case and the connection plate are, for example, projection welded. Even when the bottom surface portion is deformed to bulge inward due to thermal effects, the deformed bottom surface portion does not adversely affect the negative electrode current collector or the electrode plate group due to the presence of the gap, The required battery capacity and stable battery performance can be ensured.
[0027]
In the inter-battery connection structure of the present invention, it is preferable that the connection plate is an integrally formed product of flat plates made of a three-layer clad material of Ni—Cu—Ni. As a result, the connection plate can be suitably welded to the nickel-plated steel sheet, which is a general material of the battery case, while ensuring good conductivity by the central Cu layer, so that the electrical resistance is reduced. This can be further reduced, and power loss in the connection body can be minimized.
[0028]
Further, in the inter-battery connection structure of the above invention, the connection plate is composed of a pair of the same shape obtained by dividing the substantially bowl shape into two along the longitudinal direction in plan view, and each of the two adjacent single cells has a low permission. It is also possible to adopt a configuration in which both side portions of each of the pair of connection plates that are bridged in the proximity of each other with a gap between them are welded and electrically connected via both connection plates.
[0029]
According to this configuration, even if the pair of connection plates is formed in a simple shape, by arranging the pair of connection plates in close proximity to each other, the same shape as the through holes and slits necessary for welding is formed between the two connection plates. Therefore, it is possible to mass-produce simple shape connection plates at low cost. In addition, when the connection plate is welded to two batteries by, for example, projection welding, there is a great advantage that the invalid diversion during welding can be completely eliminated.
[0030]
Further, in the inter-battery connection structure of the above invention, the connection plate is formed with a narrowed thin portion at least at a location close to each other at each contact location with two adjacent single cells, and the narrowed thickness portion is interposed therebetween. It is also possible to adopt a configuration in which laser welding or beam welding is used to weld the unit cell.
[0031]
According to this configuration, in addition to being able to greatly reduce the electric resistance by making the distance of the current path between two adjacent single cells the shortest, laser irradiation or beam welding is performed by irradiating the thin aperture portion with light. As a result, the drawn thin wall portion can be melted first and sufficient heat can be applied to the welded portion, so that sufficient welding strength can be ensured, and the reliability of welding is improved.
[0032]
Furthermore, in the inter-battery connection structure of the above invention, the pair of auxiliary pieces extending in the orthogonal direction from both sides along the longitudinal direction of the connection plate has a length extending from the coupling portion to at least half of the connection portions on both sides. It is preferable that the connecting plate has a configuration in which the auxiliary piece is bridged between two adjacent single cells in an arrangement facing the opposite direction of the single cells and is welded to both the single cells.
[0033]
According to this configuration, since the auxiliary plate is welded across the two unit cells in an arrangement in which the auxiliary piece does not interfere with the unit cell, the connection plate is line-symmetric with respect to the center line along the longitudinal direction. Since it can be made into a shape, there is no directionality when attaching to two unit cells, and attachment work becomes easy. Moreover, since the auxiliary | assistant piece is formed as long as possible, the mechanical strength as a connection board improves further.
[0034]
Furthermore, in the inter-battery connection structure of the above invention, the pair of auxiliary pieces extending in the orthogonal direction from both sides of the connection plate has a length extending from the coupling portion to at least half of the connection portions on both sides, and one end of each of the auxiliary pieces. It is preferable that the side is formed in a curved shape in contact with the outer surface of the battery case, and the other end side is formed in a curved shape in contact with the outer surface of the connection electrode portion.
[0035]
According to this configuration, when the connecting plate is bridged between the two unit cells, the outer surface of the battery case and the connection electrode portion are fixed to the unit cells in a temporarily fixed state. Can be easily and accurately welded, and there is an advantage that the mechanical strength of the connecting structure of two unit cells by the connecting plate is further improved.
[0036]
The battery module according to the present invention has a substantially rectangular parallelepiped outer shape having a thickness that is substantially half the length of the battery cell in the axial direction of the battery, and has a square cross-sectional shape that can accommodate the cylindrical battery. The battery case includes a holder case having a pair of case halves made of synthetic resin in which a plurality of battery storage portions penetrating in the thickness direction are arranged in a single row or a plurality of rows. The corresponding battery storage portions communicate with each other and are fixed to each other at a relative position where a plurality of battery storage portions capable of storing the entire unit cell are formed, and are individually inserted into the respective storage portions. In addition, each of the unit cells is pulled out from the outer side edge of each of the battery housing portions of the case halves with the holding projections projecting into the battery housing portion coming into contact with both end surfaces in the battery axial direction. The battery in a stopped state Each of the two adjacent cells stored in the storage unit are electrically connected to each other and mechanically connected by the inter-battery connection structure according to any one of claims 1 to 6, and the holder Openings on both sides in the thickness direction of the case are respectively closed by lid members fixed thereto, and each lid member has a gap between each of the unit cells and the four partition walls of the battery housing portion having a rectangular cross section. It is characterized in that a heat radiation hole having a shape corresponding to each of the gaps is formed at a corresponding location.
[0037]
In this battery module, when a pair of case halves are connected to each other in a state in which a single battery is inserted into each of the battery storage portions to form a holder case, each battery of both case halves The unit cells stored in the storage unit are held in a non-removable manner by the holding projections, and the holder case is in a block form storing the required number of unit cells. Therefore, in the next process, between each two adjacent unit cells It is extremely easy to carry out the welding work by laying the connecting plate on the plate, and the productivity is greatly improved.
[0038]
In this battery module, the outer dimensions are uniquely determined by the molding accuracy of the holder case made of synthetic resin, and there is no dimensional variation after the assembly process, and the shape is highly accurate. Become. In addition, since each unit cell is stored in an individual battery storage part, it is kept in a completely electrically insulated state, so that an insulating ring, a resin outer tube, etc. in a conventional battery module become unnecessary, and the material cost is reduced. Can be reduced and productivity can be improved. In addition, since the connection plate has a bowl shape corresponding to the entire outer shape of the two unit cells and does not block the gap between the cells, between each unit cell and the four partition walls of the battery storage unit, Since gaps with an equal cross-sectional area are formed and these gaps are communicated to the outside of the holder case through the heat dissipation holes of the lid members on both sides, each cell is surrounded from one side of the holder case. An effective heat dissipation passage that passes through to the other side is formed, and each unit cell is extremely effectively cooled by the wind flowing through the heat dissipation passage, and all of the relatively large number of unit cells are Can be cooled evenly.
[0039]
In the battery module of the above invention, the holder case is preferably configured such that both case halves are coupled to each other with a rectangular elastic sheet interposed between the opening end faces. As a result, during manufacturing, when the cells are inserted into these battery housings and the cells are combined with each other, the height variation in the cell axial direction of the cells is absorbed by the elastic deformation of the elastic sheet. And a holder case in the form of a block can be easily assembled. In addition, when functioning as a battery module, shocks and vibrations applied from the outside of the holder case are absorbed by the elastic sheet and do not act directly on each single cell. Even when mounted and used in an environment subject to frequent vibrations and shocks, each unit cell can be securely held in a protected state.
[0040]
In the battery module of the above invention, the battery housing part of the holder case has a width of three first partition walls out of four forming a quadrangular cross section larger than the outer diameter of the unit cell, and the other one first The width of the two partition walls is formed in a rectangular shape in plan view equal to the outer diameter of the unit cell, and the distance between the tips and the distance to the second partition walls on the inner surface of each of the first partition walls. It is preferable that three support ribs each having a protruding length equal to the outer diameter of the unit cell are protruded.
[0041]
According to this configuration, the volume of the gap between the unit cell and the partition wall of the battery storage unit is increased by the protruding length of the support rib, the amount of air flowing through the gap is increased, and the battery storage unit having a rectangular shape in plan view In these four corners, voids having substantially the same volume are formed between the unit cell and the four partition walls of the battery storage unit. As a result, a uniform heat dissipation passage that passes through the periphery of each unit cell from the one side of the holder case to the other side is formed around each unit cell, so that a relatively large number of unit cells are formed. Are all evenly and efficiently cooled. Therefore, in a battery pack configured by using a large number of battery modules, a cooling mechanism such as a cooling fin blade provided in a conventional battery pack is not necessary.
[0042]
Furthermore, in the battery module of the above invention, holding protrusions that protrude from the outer ends of the three support ribs to the inside of the battery housing portion and contact the end surfaces of the battery case in the battery axial direction are integrally provided on the three support ribs. The two holding projections located opposite to each other at the opening on both sides of each battery storage portion are set to a separation distance equal to the length between both end surfaces of the unit cell in the battery axial direction. It is preferable that the arrangement is provided.
[0043]
According to this configuration, it is possible to set the projection length of the holding protrusion into the battery storage portion to be short while forming a relatively large volume gap between the unit cell and the partition wall of the battery storage portion by the support rib. In addition, each cell can be folded in a direction perpendicular to the battery axial direction with the outer surface of the battery case coming into contact with four locations of a pair of opposing support ribs, another support rib, and an opposing partition wall of the battery storage portion. Since the holding protrusions are in direct contact with both end surfaces in the battery axial direction and are held in the battery axial direction without being rattled, each unit can be stored while storing a relatively large number of single cells. The battery is securely held in a protected state even when it is installed in an environment subject to severe vibration or impact such as an electric vehicle, electric bicycle or electric tool, and there is no risk of destruction. Absent.
[0044]
Furthermore, in the battery module of the above invention, a positive electrode terminal and a negative electrode terminal for external connection are respectively provided by insert molding at one end or both ends of the battery housing portion in at least one of the pair of holder cases. The positive electrode terminal, the negative electrode terminal, and the cells adjacent to each of the positive electrode terminal and the negative electrode terminal are connected to each other by a connection plate, and are connected to each other by fixing members on both sides in the direction orthogonal to the arrangement direction in the two cases. It is preferable that the connecting member is provided by insert molding.
[0045]
According to this configuration, since the positive electrode, the negative electrode terminal, and the connecting material are integrally provided in the holder case by insert molding, the number of assembly steps is reduced as the number of parts is reduced. In addition, since the connecting member formed by insert molding is integrally provided outside the holder case having a substantially rectangular parallelepiped outer shape, unlike a conventional battery module in which a required number of cells are simply connected in series in the battery axial direction. By connecting the positive electrode terminal and the negative electrode terminal to predetermined electrode terminals and fixing them to a mounting part such as a device via a connecting member, it can be used as it is as a drive power source for various devices.
[0046]
In the battery pack according to the present invention, a plurality of attachment members are provided on each side of the battery module holder case according to any of the present invention along the arrangement direction of the unit cells by insert molding. A plurality of battery module units configured to overlap each other at a relative position where the direction of the thickness direction is reversed with respect to one of the battery modules are arranged side by side and cover at least the plurality of battery module units. Two exterior plates are connected to each other by fixing members inserted through the two mounting members facing each other and fixed to the battery module, and each of the battery module units has 2 The battery modules are integrated with the fixing member, and a positive electrode terminal and a negative electrode for external connection of each of the battery modules Children are electrically connected by the bus bar, the unit cells of internal to each battery module is characterized in that connected in series or parallel connection.
[0047]
In this battery pack, the battery module has an extremely high precision outer shape that is uniquely determined by the molding accuracy of the holder case, and a relatively large number of single cells are stably stored and held in the holder case. Thus, the battery modules can be easily connected by a simple fixing means such as a fixing screw to form a battery module unit, and at least two battery module units are arranged around the battery module unit. It can be easily assembled into a very robust structure while being easily integrated with a single exterior plate by simple fixing means such as fixing screws. Therefore, this battery pack can be manufactured with extremely high productivity. Further, in this battery pack, since the fixing member that connects the two exterior plates to each other is also used for fixing the pair of battery modules, there is an advantage that both the number of the fixing members and the number of connecting steps can be reduced. is there.
[0048]
In addition, since the battery module has a block configuration that stably holds a large number of single cells, when changing the number of battery modules, only the shape of the exterior plate that can be formed by bending the plate material is changed. As compared with the case where the holder case is formed with a new mold as in the conventional battery pack, it can be handled at an extremely low cost. In addition, since the heat dissipation passages of the battery modules communicate with each other between the two stacked battery modules in the battery module unit, even when a large number of battery modules are integrated, Since the cooling function is reliably ensured, a cooling mechanism such as a conventional cooling fin blade becomes unnecessary.
[0049]
In the battery pack of the above invention, a plurality of installation surfaces in which the attachment member of the battery module is brought into contact with the at least two exterior plates and connected by a fixing member, and each of the installation surfaces bulge outward. There is a recess formed inside, and a heat dissipation passage communicating between the recess and the battery module to the battery housing space of the battery module via the heat dissipation hole of the lid member. It is preferable to have a formed configuration.
[0050]
According to this configuration, since the heat dissipation passage formed between the recess of the exterior plate and the battery module is communicated with the battery storage space of the battery module, the battery module and the exterior plate Since an effective heat dissipation passage can be formed between them, a large number of single cells can be cooled extremely efficiently and evenly, eliminating the need for temperature sensors, blowers, etc. provided in conventional battery packs Thus, the cost can be considerably reduced, and the overall shape can be reduced while obtaining the required cooling effect.
[0051]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing a relative arrangement of each component of a battery module 12 according to an embodiment of the present invention. In this embodiment, a case where 20 cylindrical unit cells 13 of the same type and the same standard are connected in series is illustrated, and this unit cell 13 is, for example, a nickel hydrogen secondary battery.
[0052]
First, the configuration of the unit cell 13 applied to the battery module 12 will be described. 2A is a perspective view showing the unit cell 13, and FIG. 2B is a cross-sectional view taken along line AA of FIG. The battery case 14 also serving as the negative electrode has a bottomed cylindrical shape with one end opened, and a known positive electrode plate and negative electrode plate are interposed in the battery case 14 between them. A group of electrode plates 17 wound in a spiral shape and an electrolytic solution (not shown) are accommodated. The opening of the battery case 14 is closed by a sealing body 18 constituted by a sealing plate 19, an insulating gasket 20, a metal cap 21 and a rubber valve body 22.
[0053]
That is, the peripheral edge of the sealing plate 19 is electrically insulated from the battery case 14 via the insulating gasket 20, and is fixed to the opening of the battery case 14 that has been crimped via the insulating gasket 20. Thus, the opening of the battery case 14 is closed. The sealing plate 19 is formed with concentric arrangements of ring-shaped connection electrode portions 28 projecting outward in the battery axial direction in the vicinity of the peripheral edge. The positive electrode lead 26 drawn out from the electrode plate group 17 is connected to the sealing plate 19. Therefore, the connection electrode portion 28 formed on the sealing plate 19 serves as a positive electrode terminal. In addition, a circular concave portion 29 that is recessed inward is formed in a concentric arrangement at the center of the bottom surface of the battery case 14 serving as a negative electrode.
[0054]
The rubber valve body 22 is housed in a space formed between the recess 23 at the center of the sealing plate 19 and the metal cap 21, and closes the gas discharge hole 24 drilled in the recess 23. . When the gas pressure inside the battery rises abnormally and reaches the valve opening pressure, the rubber valve body 22 is elastically deformed by receiving the gas pressure acting through the gas discharge hole 24 and opens the gas discharge hole 24. . Thereby, the gas inside the battery is discharged to the outside of the battery case 14 through the gas discharge hole 24 and the gas discharge hole 27 of the metal cap 21.
[0055]
Returning to FIG. 1, each unit cell 13 described above is contained in a holder case 30 in which an upper case half 30 A and a lower case half 30 B are combined with each other with an elastic sheet 36 interposed therebetween. Stored. Both case halves 30A and 30B are both made of synthetic resin, and both have a substantially rectangular parallelepiped outer shape having a thickness (height) slightly larger than half the length of the battery cell 13 in the battery axial direction. The inside of the battery cell is partitioned by a partition wall, and 10 battery storage portions 31 that can individually store half of each of the 20 unit cells 13 are arranged in two rows. Each battery storage unit 31 has a rectangular shape in plan view surrounded by four partition walls, and penetrates in the thickness direction. Note that the battery housing portions 31 of both case halves 30A and 30B have substantially the same shape, and therefore are given the same reference numerals, and details of the battery housing portions 31A and 31B will be described later. The elastic sheet 36 has a rectangular shape in plan view corresponding to the butted opening end faces of both case halves 30A and 30B.
[0056]
The external connection positive terminal 32 and the external connection negative terminal 33 made of nuts are inserted on the outer surface of one end side (the left end side in the figure) of the arrangement direction (longitudinal direction) of each battery storage portion 31 in the upper case half 30A. The external connection positive electrode terminal 32 and the external connection negative electrode terminal 33 made of nuts are arranged in an arrangement opposite to the one end side on the outer surface of the other end side (right end side in the figure). It is integrally provided by molding. Further, a plurality of connecting members 34 made of nuts (three are exemplified in the embodiment) are arranged on both outer surfaces of both case halves 30A and 30B in the arrangement direction, and are integrated by insert molding. In addition, a plurality of mounting members 45 (two are exemplified in the embodiment) are arranged between the connecting members 34 and are integrally provided by insert molding. Each connecting member 34 can be screwed with a fixing screw from both above and below. The attachment member 45 is a small-diameter pipe through which a fixing screw is simply inserted.
[0057]
Each unit cell 13 is individually inserted into each battery storage portion 31 of the holder case 30 formed by combining both case halves 30A and 30B, and held in an arrangement in which the battery axes are parallel to each other. In the state, the two adjacent each other in the arrangement direction in the front row and the rear row in the figure are connected in series by the connection plate 38 alternately and sequentially. However, the unit cell 13 at the left end in the rear row in the figure has its bottom surface part of the battery case 14 connected to the positive terminal 32 for external connection via the connection plate 38, and the unit cell 13 at the left end in the front row has its own connection. The electrode portion 28 is connected to the external connection negative electrode terminal 33 through the connection plate 38. Further, the unit cell 13 at the right end of the rear row in the figure has its own connection electrode portion 28 connected to the external connection negative electrode terminal 33 via the connection plate 38, and the unit cell 13 at the right end of the front row has its own battery case 14. Is connected to the external connection positive terminal 32 via the connection plate 38.
[0058]
FIG. 3 shows an inter-battery connection structure according to an embodiment of the present invention applied to the connection of unit cells 13 in the battery module same as above, (a) is a plan view, (b) is a front view, and (c). FIG. 4 is an enlarged cross-sectional view taken along line BB in FIG. The connection plate 38 is made of a three-layer clad plate of Ni—Cu—Ni, and has a pair of connection portions 35 that have an arc shape with a diameter substantially equal to the outer diameter of the connection electrode portion 28, and both the connection portions. It is an integral body having 35 linear connecting portions 41 that connect mutually opposing locations. The width of the connecting portion 41 is set sufficiently smaller than the diameter of the connecting portion 35. Therefore, the connection plate 38 is constricted at the center and has a substantially bowl shape in plan view.
[0059]
The pair of connection portions 35 are formed with through holes 39 having a diameter substantially equal to the inner diameter of the connection electrode portion 28, and both outer sides along the longitudinal direction of the connection plate 38 from both sides in the radial direction of the through holes 39. Slits 40 extending in the direction are formed. Further, four projection welding projections 42 are formed in advance on the pair of connection portions 35 at equal intervals of 90 ° on the same circle outside the through holes 39. Further, the auxiliary pieces 25 having a length including the connecting portion 41 to the half of each connecting portion 35 on both sides of the connecting plate 38 are formed by bending at right angles to the connecting portion 41 and the connecting portion 35. Has been. Therefore, the connection plate 38 has a line-symmetric shape with respect to the central portion in the longitudinal direction. The connection plate 38 is attached so as to span a pair of adjacent unit cells 13 with the pair of auxiliary pieces 25 facing outward, but the connection plate 38 has a line-symmetric shape with respect to the central portion in the longitudinal direction. Therefore, since there is no directionality in the attachment, it can be attached easily. Moreover, in this embodiment, the case where the connection plate 38 is projection-welded via the protrusion 42 is illustrated.
[0060]
In the inter-battery connection structure, when the connection plate 38 is placed between two adjacent unit cells 13, four projection weldings on one side (left side in FIG. 3) of the connection plate 38 are performed. The projections 42 abut on the connection electrode portion 28 of the unit cell 13, and the four projections 42 on the other side (right side in FIG. 3) abut on the peripheral portion of the recess 29 in the bottom surface of the unit cell 13. The well-known projection welding is performed. In this projection welding, the connecting portions 35 on both sides of the connecting plate 38 that is a simple flat plate are ring-shaped of one unit cell 13 of the two unit cells in which the respective battery axes are arranged in parallel. Since it can be performed in a stable posture supported across the connecting electrode portion 28 and the bottom surface portion of the battery case 14 of the other unit cell 13, welding in an unstable posture as in the conventional inter-battery connection structure described above. Therefore, there is no risk of problems such as poor bonding, and the yield is greatly improved.
[0061]
In projection welding, in the left unit cell 13 in FIG. 3, for example, the positive side welding electrode is brought into contact with the side surface of the connection electrode portion 28, and the negative side welding electrode is opposed to the protrusion 42 on the connection plate 38. A high voltage is applied between the welding electrodes from the inverter DC power supply. Thereby, the welding current flows in a concentrated manner between the projection 42 and the connection electrode portion 28 having a very small contact resistance because the contact area is small, and the four projections 42 are melted by the heat generated thereby. The connection part 35 and the connection electrode part 28 are welded to each other through a nugget in which the protrusion 42 is melted in a state where the connection part 35 and the connection electrode part 28 are completely adhered to each other. Here, each connection part 35 and the connection electrode part 28 of the connection plate 38 can be firmly joined via the four protrusions 42 by one projection welding.
[0062]
Further, also in the right unit cell 13 in FIG. 3, both the negative side welding electrode is brought into contact with the outer peripheral surface of the battery case 14, and the positive side welding electrode is brought into contact with the opposite portion of the projection 42 on the connection plate 38. By applying a high voltage from the inverter DC power source between the welding electrodes, the connection plate 38 and the bottom surface portion of the battery case 14 can be firmly joined via the nugget in which the four protrusions 42 are melted by one projection welding.
[0063]
Therefore, since each two adjacent single cells 13 can be connected to each other by two projection weldings, for example, in the conventional inter-battery connection structure shown in FIG. 14, the welding process is repeated a total of eight times. In this embodiment, each two adjacent single cells 13 in the 20 single cells 13 can be connected by two weldings, so that the number of weldings can be greatly reduced, and the productivity is accordingly increased. Is significantly improved. Further, at the time of projection welding, the ineffective diversion can be remarkably reduced by the through holes 39 and the pair of slits 40.
[0064]
Further, in the inter-battery connection structure, the connection on both sides of the connection plate 38 is made close to the ring-shaped connection electrode portion 28 of one unit cell 13 and the outer peripheral portion outside the recess 29 of the other unit cell 13. Since the portion 35 is welded, the electric resistance can be greatly reduced with the distance L of the current path between two adjacent unit cells 13 shown in FIG. On the other hand, in the conventional inter-battery connection structure shown in FIG. 14, the longest planar portion 7 and cylindrical portion 4 in the dish-like connecting body 3 are connected to two adjacent single cells B 1 and B 2. Therefore, the distance of the current path between both the unit cells B1 and B2 becomes longer and the electric resistance becomes higher.
[0065]
In addition, in the inter-battery connection structure, since the connection plate 38 is formed of a clad material having a three-layer structure, the Ni layer on both sides is attached to the battery case 14 while ensuring good conductivity by the central Cu layer. Since it can weld suitably with the nickel plating steel plate which is the general raw material of this, an electrical resistance can be reduced further. As described above, the inter-battery connection structure can minimize power loss at the connection plate 38.
[0066]
Further, in the inter-battery connection structure, the outer surface of the ring-shaped connection electrode portion 28 and the protrusion of the connection plate 38 that protrude laterally and upwardly from the metal cap 21 that holds the rubber valve element 22. Since projection welding is performed by bringing the welding electrodes into contact with the opposite locations of 42, no current flows through the metal cap 21, and there is no possibility of deformation of the rubber valve body 22 due to the thermal effect of the metal cap 21. Thereby, in this connection structure between batteries, the required valve operation | movement of the rubber valve body 22 is always securable. On the other hand, in the conventional structure shown in FIG. 14, projection welding must be performed by bringing the welding electrode into contact with the metal cap 1 at a position opposite to the protrusion 9 of the connection body 3. Due to the influence, the rubber valve element 22 was deformed inwardly.
[0067]
Further, in the above-described inter-battery connection structure, the concave portion 29 that is recessed inward is provided on the bottom surface of the unit cell 13, so that the negative electrode current collector 43 and the battery case 14 can be connected as shown in FIG. Since a slight gap b can be provided between the bottom surface portion and the bottom surface portion of the battery case 14 and the connection plate 38, the bottom surface portion is deformed so as to bulge inward due to thermal effects. Even so, the deformed bottom surface portion does not adversely affect the negative electrode current collector 43 and the electrode plate group 17. Therefore, in the inter-battery connection structure, a required battery capacity and a stable battery function can be ensured. On the other hand, in the conventional battery-to-battery connection structure, particularly in the structure in which the cells are directly connected without using a connecting body as in the third prior art described above, the negative electrode current collector and the electrode plate group are not connected during projection welding. The battery case was deformed by receiving pressure from the bottom surface of the battery case that bulges in the direction.
[0068]
The connection plate 38 has a bowl shape in a plan view with a narrowed central portion for the purpose of ensuring a uniform and large cross-sectional ventilation path around the unit cell 13 when a battery module described later is configured. However, an increase in electrical resistance at the narrow connecting portion 41 can be suppressed by the auxiliary piece 25, and the mechanical strength of the connection plate 38 itself is improved by the auxiliary piece 25.
[0069]
In the process of manufacturing the battery module 12 in the manufacturing completed state shown in FIG. 5 (b), the inter-battery connection structure is configured as shown in FIG. 5 (a). With the single battery 13 inserted in the case 31, both case halves 30A and 30B are brought into contact with each other, and the fixing screws 16 are screwed into a total of six connecting members 34 facing each other in the case halves 30A and 30B. By fastening, both case halves 30A and 30B are fixed to each other, and the holder case 30 is assembled. In FIG. 4, as shown in FIG. 5A, after the 20 unit cells 13 are accommodated and the holder case 30 is assembled, each two adjacent unit cells 13 are connected to each other by the connection plate 38. (A) is a partial plan view, (b) is a sectional view taken along the line CC of (a), and (c) is a sectional view taken along the line DD of (a).
[0070]
In FIG. 4, the battery housing portions 31 of both case halves 30A and 30B have a rectangular shape in plan view that is long in the vertical direction in the figure, and support ribs 55 are provided from the center of the inner surface of the opposing partition in the longitudinal direction of the rectangle. Each projectes integrally. The two support ribs 55 are set so that the distance between the respective tips is substantially the same as the outer diameter of the battery case 14 of the unit cell 13, and abut against the unit cell 13 at both radial positions on the outer surface thereof. I support it. Two locations that are 90 ° apart from each other on the outer surface of the battery case 14 are in contact with the partition walls of the battery housing 31.
[0071]
Further, the battery case 14 protrudes inward from the outer end of the support rib 55 and the opening edge of one partition wall of the two partition walls where the support rib 55 is not formed. The holding protrusions 56 that are in contact with both end faces in the battery axial direction are integrally formed. The distance between the opposing holding projections 56 of both case halves 30A and 30B is set to be equal to the height between both end faces of the battery case 14 excluding the connection electrode portion 28 in the unit cell 13. The variation in the height of the unit cell 13 is absorbed by the elastic deformation of the elastic sheet 36.
[0072]
Therefore, the unit cell 13 accommodated in the battery accommodating part 31 is in the horizontal direction, with four equally spaced 90 ° contacts on the outer surface of the battery case 14 respectively contacting the pair of support ribs 55 and the two partition walls. Are prevented from moving in the vertical direction by the three holding projections 56 that are in contact with the upper end surface and the lower end surface, respectively, and are held in the battery storage unit 31 without rattling. .
[0073]
Each cell 13 is inserted into the battery housing 31 as it is without being attached to a laterally projecting body such as a connection body or an insulating ring as in the conventional structure, and 4 at regular intervals of 90 ° on the outer surface. The portion contacts the pair of support ribs 55 and the two portions of the partition wall, and is prevented from moving in the horizontal direction, and is vertically moved by each of the three holding projections 56 that respectively contact the upper end surface and the lower end surface. By preventing the movement, even when subjected to vibration or impact, it is securely held without rattling.
[0074]
Further, in the state where the unit cells 13 inserted into the battery storage unit 31 are connected by the connection plate 38, the outer peripheral surface of the unit cell 13 and the battery storage unit 31 are clearly shown by the horizontal parallel lines in FIG. The gaps 44 penetrating the inside of the battery housing 31 are formed at four positions between the four partition walls. These gaps 44 become effective heat dissipation spaces of the unit cells 13 when the battery module 12 functions.
[0075]
That is, the four gaps 44 are expanded in volume by the protruding length of the support rib 55 as compared with the case where the outer surface of the battery case 14 is brought into contact with the four partition walls of the battery housing 31, and the inside of the gap 44 is filled. As the amount of air flowing increases, the connecting plate 38 is provided with a connecting portion 41 in the center of the connecting plate 41 so that the gap between the two single cells 13 is not blocked. Compared to the case where the four cells 44 are provided, since the four gaps 44 have substantially the same cross-sectional shape, the cooling effect can be uniformly applied to the entire outer periphery of the unit cell 13. Can be cooled. Furthermore, since the storage spaces 47 of the auxiliary pieces 25 provided above and below the holder case 30 communicate the four gaps 44 with each other, the cooling effect of the unit cell 13 is further improved from this point.
[0076]
Next, returning to FIG. 1, the description of the battery module 12 will be continued. As described above, both case halves 30A and 30B are combined with each other in a state in which the unit cell 13 is inserted into each battery storage unit 31, and the holder case 30 is assembled. The battery 13 is connected by the connection plate 38, and the connection structure between batteries is comprised. After that, the upper and lower openings of the holder case 30 are covered with synthetic resin upper and lower lids 53 and 54, and the upper and lower lids 53 and 54 and the holder case 30 are covered. This is sealed by ultrasonic welding of the peripheral edge of the opening. In the upper lid 53 and the lower lid 54, heat radiation holes 57 each having a shape corresponding to the gap 44 formed between the unit cell 13 and the four partition walls of the battery housing 31 of the holder case 30 are opposed to the gap 44. It is formed at each position.
[0077]
Next, an assembly procedure of the battery module 12 will be described. In the state where the respective components are arranged as shown in FIG. 1, first, 20 unit cells 13 are inserted into the respective battery storage portions 31 of the lower case half 30B from the upper opening. At this time, the unit cell 13 is supported without the bottom surface portion being pulled out below the battery housing portion 31 by the holding projection 56.
[0078]
Subsequently, the elastic sheet 36 is attached to the upper end opening edge of the lower case half 30B by means such as sticking. After that, in the state where the upper case half 30A is inserted from the lower side into the respective battery storage portions 31 with the upper half of the unit cell 13 protruding above the lower case half 30B in FIG. As shown, the lower case half 30 B is abutted against the elastic sheet 36. Thereby, each connection member 34 of both case half bodies 30A and 30B opposes up and down, and the holder case 30 is assembled by screwing and fastening the fixing screw 16 to each of the two upper and lower connection members 34. At this time, some variation in the height of the unit cell 13 is absorbed by the elastic deformation of the elastic sheet 36.
[0079]
Each unit cell 13 accommodated in the battery housing part 31 of the holder case 30 is held in a state where it is not detached from the battery housing part 31 by the upper and lower holding projections 56. In this state, on the upper surface side of the holder case 30, the connection plate 38 is bridged and welded between each two adjacent unit cells 13 to constitute the above-described inter-battery connection structure. The single cells 13 are connected to each other. At this time, the two unit cells 13 at the left end of the figure are also connected to the external connection positive terminal 32 and the external connection negative terminal 33 by the connection plate 38. Subsequently, after the upper lid 53 is inserted into the upper end opening of the holder case 30, the upper end opening of the holder case 30 is sealed by ultrasonic welding between the peripheral end of the upper lid 53 and the upper end opening peripheral edge of the holder case 30. Stop.
[0080]
Next, the holder case 30 whose upper end opening is covered with the upper lid 53 is turned upside down, and the connection plate 38 is bridged and welded between each two adjacent single cells 13, whereby the above-described inter-battery connection structure. The two adjacent unit cells 13 are connected to each other. Thus, the 20 unit cells 13 are fixed in the holder case 30 in a state where they are electrically connected in series and mechanically connected. Subsequently, the lower lid 54 is fitted into the opening of the holder case 30, and the peripheral end of the lower lid 54 and the opening peripheral edge of the holder case 30 are ultrasonically welded to seal the lower end opening of the holder case 30. Then, the battery module 12 shown in FIG.
[0081]
Note that the means for fixing the upper lid 53 and the lower lid 54 to the holder case 30 is not limited to the ultrasonic welding described in the above embodiment, and for example, a fixing screw may be used.
[0082]
The battery module 12 assembled as described above can obtain the same effects as described in the inter-battery connection structure of FIG. 3, and in addition, a plurality of single cells B1 to B6 as shown in FIG. Unlike the unstable conventional battery modules that are connected in a line in the battery axis direction, each unit cell 13 can be reliably held in a state where it can be protected from vibration and impact.
[0083]
That is, in the battery module 12, each unit cell 13 is stored in each battery storage unit 31 of the holder case 30 in an arrangement in which each battery axis is parallel, and each unit cell 13 is stored in the battery storage unit 31. The outer surface of the battery case 14 comes into contact with four locations of the pair of opposing support ribs 55 and the opposing partition wall of the battery storage portion 31 and is stored in a state in which the outer surface of the battery case 14 is held without being rattled in the direction orthogonal to the battery axial direction. That is, the unit cell 13 is held by the three holding projections 56 directly on the both end surfaces in the battery axial direction so as to be held in the battery axial direction without shaking, and the case halves 30A and 30B A relatively large number of single cells 13 are accommodated by the impact and vibration applied from the outside in the battery axial direction of the single cells 13 by the elastic sheet 36 interposed therebetween and not acting directly on each single cell 13. Shinaga However, each cell 13 is securely held and destroyed even when the battery module 12 is mounted in an environment subject to severe vibration or impact such as an electric vehicle, electric bicycle or electric tool. There is no risk of occurrence.
[0084]
In addition, at the four corners of the battery housing part 31 that is rectangular in plan view, the gaps that have substantially the same volume between the unit cell 13 and the partition wall of the battery housing part 31 and that have a relatively large cross-sectional area are formed. 44 communicates with the outside of the upper and lower surfaces of the battery module 12 through the heat release holes 57 of the upper and lower lids 53 and 54, respectively. As a result, a heat dissipation passage is formed through the periphery of each unit cell 13 from one side of the holder case 30 and penetrating to the other side, so that each unit cell 13 circulates in the heat dissipation passage. The wind is extremely effectively cooled, and all of the relatively large number of single cells 13 are evenly cooled. Therefore, a battery pack configured by using a large number of battery modules 12 does not require a cooling mechanism such as a cooling fin blade provided in a conventional battery pack. Details of this battery pack will be described later.
[0085]
Further, in the battery module 12, each unit cell 13 is stored and surrounded by the partition walls of the four sides of each battery storage unit 31, so that the unit cells 13 are kept in a completely electrically insulated state. Therefore, an electrical insulating property such as vinyl chloride covering the outer peripheral surface of each of the unit cells B1 to B6 connected in series or the insulation ring 11 used to insulate the unit cells B1 to B6 in the conventional battery module. In addition, a resin-made outer tube having heat shrinkability is not necessary, and material costs can be reduced and productivity can be improved.
[0086]
Moreover, in the conventional battery module, since the connecting body 3 and the insulating ring 11 protrude from the side of each of the cells B1 to B6 connected in series in the battery axial direction, the outer shape, length, and parallelism are manufactured with high accuracy. However, in the battery module, the outer dimensions are uniquely determined by the molding accuracy of the holder case 30 made of synthetic resin, and there is no variation in dimensions after the assembly process. The shape is highly accurate.
[0087]
Further, when the battery module 12 is assembled in a manufacturing process, the case halves 30A and 30B are combined with each other in a state in which the required number of single cells 13 are housed in the battery housing 31 and the holder case 30 is assembled. In addition, since each unit cell 13 is fixed in a holder case 30 so that it cannot be removed and rattled, welding is performed by connecting a connecting plate 38 between each two adjacent unit cells 13. The work becomes easier and there is almost no risk of poor bonding.
[0088]
Further, as described above, the battery module 12 includes a relatively large number (20 in the embodiment) of single cells 13 enclosed in the holder case 30 and held in a robust structure. Since the connecting member 34 made of an insert-molded nut is integrally provided on the outside of the battery 30, unlike the conventional battery module in which six cells B1 to B6 are simply connected in series in the battery axial direction. It can also be used as it is as a drive power source for an electric bicycle or electric tool. In particular, when the battery module 12 is used as a battery pack by connecting a large number of the battery modules 12 to a motor drive power source of an electric vehicle or the like, a more remarkable effect can be obtained. Next, a battery pack configured using the battery module 12 will be described.
[0089]
FIG. 6 is a perspective view showing a relative arrangement in the process of manufacturing a battery pack in which a total of 120 unit cells 13 are connected in series using six battery modules 12. In this battery pack, three battery modules 12 are arranged in parallel and juxtaposed in a state of being close to each other, and the other three battery modules 12 are respectively placed on the upper surfaces of the three battery modules 12. Superimpose them upside down. At this time, the two battery modules 12 on the upper and lower sides are abutted in an inverted arrangement, so that a total of ten connecting members 34 face each other in close proximity to each other. Fixing screws (not shown) are screwed and fastened to the 10 sets of connecting members 34 that are close to each other. As a result, as shown in FIG. 8, three battery module units 48 in which the two battery modules 12 are connected to each other in an overlapping state are completed.
[0090]
Between the two upper and lower battery modules 12 in the battery module unit 48, the corresponding heat dissipation holes 57 of the upper lid 53 and the lower lid 54 that are in contact with each other are in communication with each other. Thereby, between each of the two upper and lower battery modules 12 in each battery module unit 48, a heat dissipation passage that passes from the one surface side to the other surface side through the periphery of each single cell 13 is formed. Also in the battery module unit 48 in which the two battery modules 12 are connected, the cooling function of the individual single cells 13 is reliably ensured.
[0091]
FIG. 7 is a perspective view showing a manufacturing process in which a battery pack is configured using three battery module units 48, and FIG. 8 is an embodiment of the present invention configured using the three battery module units 48. It is the arrow line view which looked at the battery pack 49 which concerns on from the P direction of FIG. However, this figure is an arrow view seen from the P direction excluding the bus bar 51 described later. In this battery pack 49, three sets of battery module units 48 are attached to a pair of upper and lower exterior plates 50 and front and rear ends (left end and right end in FIG. 7) of the pair of exterior plates 50. The external connection positive terminal 32 and the external connection negative terminal 33 of each battery module 12 and the connection plate 38 led out to the electrode extraction portion 37 are electrically connected to each other so that a total of 120 unit cells 13 are connected in series or in parallel. These are integrated by using a pair of bus bars (shown in FIG. 7) 51 to be connected to each other.
[0092]
The pair of exterior plates 50 are formed by bending along the longitudinal direction groove-like recesses 52 that form a heat radiation space communicating with the above-described heat radiation passage that penetrates the three battery module units 48 in the vertical direction. Yes. Between each of the recesses 52, there are provided two mounting surfaces 58 for supporting each mounting member 45 of each of the two adjacent battery module units 48, and in the vicinity of both ends of the exterior plate 50. Are provided with two attachment surfaces 59 on which the attachment members 45 of the battery module units 48 located on both sides are respectively supported. Further, a pair of connecting pieces 60 are formed on the exterior plate 50 by bending both sides thereof in a direction orthogonal to the mounting surface 59. Mounting holes 61 are formed in the mounting surfaces 58 and 59 and the connecting piece 60 at predetermined locations.
[0093]
Next, an assembly procedure of the battery pack 49 will be described. The three battery module units 48 are positioned on the two adjacent mounting surfaces 58 and 59 in a positioning state in which the mounting members 45 match the mounting holes 61 of the mounting surfaces 58 and 59 with respect to the lower exterior plate 50. The three battery module units 48 are placed in a spanning arrangement, and the upper exterior plate 50 is covered with the mounting holes 61 of the mounting surfaces 58 and 59 in a positioning state in which the mounting members 45 are aligned.
[0094]
Next, the fixing screw 62 is inserted into each of the two mounting members 45 and the lower exterior plate 50 that are aligned with each other above and below the two battery modules 12 of the battery module unit 48 from the respective attachment holes 61 of the upper exterior plate 50. After being inserted into the mounting hole 61, the battery module unit 48 is attached to the pair of upper and lower exterior plates 50 from both sides by screwing and fastening to the nut 63 of FIG. As shown in FIG. 8, the connecting pieces 60 on both sides of the pair of upper and lower exterior plates 50 are connected to each other with a fixing screw 64 in a state where the respective leading ends are overlapped. Finally, the battery pack 49 is completed by attaching the pair of bus bars 51 to both ends of the upper and lower exterior plates 50 with predetermined attachment means (not shown).
[0095]
The battery pack 49 can be easily connected by a simple fixing means for screwing and fastening a pair of battery modules 12 with fixing screws 16 to form a battery module unit 48 in a block form, and a plurality of battery module units. 48 is arranged so as to surround the pair of exterior plates 50 and the pair of bus bars 51, and can be easily integrated with a simple fixing means by simply screwing and fastening the fixing screws 62. The reason why the battery module 12 can be easily assembled in such a robust structure is that the battery module 12 is configured in a rectangular parallelepiped having an extremely high-precision outer shape that is uniquely determined by the molding accuracy of the holder case 30, and a relatively large number. This is made possible by storing and holding the single cells 13 in the holder case 30 so as not to be directly subjected to vibration or impact. Therefore, the battery pack 49 can be manufactured with extremely high productivity.
[0096]
On the other hand, in the battery pack of the above-described fourth prior art, the battery module is an unstable configuration in which a plurality of single cells are arranged in a line in the battery axial direction and connected to each other via a connection body or an insulating ring. For this reason, it takes time and effort to store the battery modules in a multi-row arrangement by inserting them into the through holes in the both end walls and the intermediate wall of the complex-shaped holder case. A battery module with a connector or insulation ring protruding from the outer peripheral surface side of the battery is inserted and held in the through-hole, so it is difficult to hold the battery module without any gaps. The cell may rattle in the holder case and be damaged.
[0097]
Also in the above-described fifth prior art battery pack, a large number of battery modules having the same configuration as described above are held by holder ribs protruding from the inner surfaces of the lid case and the intermediate case in the holder case. Therefore, there are the same disadvantages as described above. The battery pack 49 can solve the above-mentioned conventional various drawbacks at once.
[0098]
Further, in the battery pack 49, in addition to the battery module 12 and the battery module unit 48 having a heat dissipation passage vertically passing through the periphery of each unit cell 13, as shown in FIG. Due to the presence of the recesses 52 in the upper and lower exterior plates 50, heat dissipation passages 67 extending in the horizontal direction in the figure are formed between the battery module units 48 and the exterior plates 50, respectively, and adjacent to each other. Between each of the two battery module units 48 and between the battery module units 48 on both sides and the connecting piece 60, a heat dissipation passage 68 is formed by the presence of the mounting surfaces 58 and 59 of the pair of exterior plates 50, and A slit-like ventilation hole 69 is formed in an auxiliary plate (not shown) that covers the outside of the bus bar 51. Therefore, in this battery pack 49, as many as 120 unit cells 13 can be cooled very efficiently and all of them can be cooled equally. On the other hand, in the conventional battery pack, since the temperature sensor for detecting the temperature of the single cell and the blower that operates based on the temperature detected by the temperature sensor are provided, the configuration is increased in size and the cost is considerably increased. Become.
[0099]
Further, the battery pack 49 has a block configuration in which the battery module 12 stably holds a large number of single cells 13. Therefore, when the number of the battery modules 12 is changed, the exterior plate 50 and the bus bar 51 It is only necessary to change the shape, and the exterior plate 50 is formed by simply bending a plate material, so that different shapes can be manufactured at a very low cost. On the other hand, in the conventional battery pack, the holder case having an extremely complicated shape has to be changed, and it takes a considerable amount of money to newly manufacture a mold for the holder case, which is quite expensive. It becomes.
[0100]
FIG. 9 shows a pair of connection plates 70 used in the inter-battery connection structure according to another embodiment of the present invention, where (a) is a perspective view, (b) is a plan view, and (c) is a connection plate 70. It is a top view which shows the connection structure between batteries comprised. The pair of connection plates 70 is a flat plate having a length extending between two adjacent unit cells 13, and has a shape corresponding to almost half of the ring-shaped connection electrode portion 28 of the unit cell 13. And a pair of connecting portions 71 provided on both side portions in the longitudinal direction, and a linear connecting portion 72 that connects the connecting portions 71 to each other. Two projection welding projections 73 are formed on each connection portion 71. Further, the auxiliary piece 25 extending from the connecting portion 72 to each half of the connecting portion 71 on both sides is bent and formed on the outer side of the connecting plate 70. Note that the connection plate 70 is formed of a three-layer clad material of Ni—Cu—Ni, as in the embodiment.
[0101]
As shown in (c), the pair of connection plates 70 are bridged between two adjacent unit cells 13 in a close-to-facing arrangement with a predetermined gap a therebetween, and each projection 73 is formed. Then, the projection 73 is welded to the connection electrode portion 28 of one unit cell 13 and the bottom surface portion of the other unit cell 13 at the nugget portion where the projection 73 is melted. The gap a between the pair of connection plates 70 is set to be approximately the same as the width of the slit 40 of the connection plate 38 of the embodiment.
[0102]
Therefore, this inter-battery connection structure requires a pair of connection plates 70 to connect the two unit cells 13, and the connection plates 70 have through-holes 39 like the connection plate 38 of one embodiment. Since it is a simple shape that can be obtained simply by bending after punching without providing a slit 40, it can be mass-produced at low cost, compared with the inter-battery connection structure of one embodiment. Almost no cost. In addition, this inter-battery connection structure can obtain the same effect as the inter-battery connection structure of one embodiment, and in addition, a pair of separate connection plates 70 are separated and combined. There is a great advantage that the diversion can be completely eliminated.
[0103]
FIG. 10 shows an inter-battery connection structure according to still another embodiment of the present invention, where (a) is an exploded perspective view and (b) is a perspective view. The connection plate 74 used in this inter-battery connection structure has a flat plate shape made of a three-layer clad material of Ni—Cu—Ni, and has a pair of through holes 39 and a pair of the connection plate 38 used in the embodiment. A pair of connecting portions 35 having a slit 40 and four projection welding projections 42 and a connecting portion 41 for connecting both the connecting portions 35 to each other are integrally formed, and are different from the connecting plate 38. A large-diameter portion 75 having a diameter substantially the same as the outer diameter of the battery case 14 is extended laterally on both sides of the half of the connecting portion 41 in the connection portion 35 on one side (left side in the figure). The only difference is that the pair of auxiliary pieces 76 whose sides extend in the orthogonal direction are arranged in the same direction as the protrusions 42.
[0104]
In this inter-battery connection structure, in addition to obtaining the same effect as that of the embodiment, as clearly shown in (b), the connection plate 74 is provided on one side of the pair of auxiliary pieces 76 (left side of the figure). Side) is in contact with the outer surface of the battery case 14 and the other side (right side in the figure) of the auxiliary piece 76 is in contact with the outer surface of the connection electrode portion 28 so as to be adjacent to each other. Since it is bridged between and fixed to both the unit cells 13 in a temporarily fixed state, projection welding of the next process can be performed easily and accurately, and the two unit cells 13 by the connection plate 74 can be connected. There is an advantage that the mechanical strength of the connecting structure is further improved.
[0105]
FIG. 11A is a plan view showing an inter-battery connection structure according to still another embodiment of the present invention, and FIG. 11B is a cross-sectional view taken along line EE of FIG. In this embodiment, instead of the projection welding in each of the above embodiments, the connection plate 77 is connected to each two adjacent single cells 13 by laser welding or beam welding. The connection plate 77 is a flat plate made of a three-layer clad material of Ni—Cu—Ni, and has a pair of connection portions 35 having through holes 39 similar to the connection plate 38 used in the embodiment, A connecting portion 41 that connects both the connecting portions 35 to each other is integrally formed, and auxiliary sides 25 having the same shape as the connecting plate 38 are bent at both sides. The difference is that a pair of thinned portions 78 concentric with the through holes 39 are arranged on the pair of connecting portions 35 such that the center portions thereof are located on a line connecting the centers of the through holes 39. It is only formed.
[0106]
In this inter-battery connection structure, in the state where the connection plate 77 is placed over the connection electrode portion 28 of one unit cell 13 and the bottom surface of the other unit cell 13 as shown in FIG. Each aperture thin portion 78 is irradiated with a light beam 79 such as a laser beam or a beam, and the aperture thin portion 78 is welded to the connection electrode portion 28 and the bottom surface portion, respectively. Are connected to each other.
[0107]
This inter-battery connection structure, like the inter-battery connection structure of each of the embodiments described above, can greatly reduce the electrical resistance by making the distance L of the current path between two adjacent unit cells 13 the shortest, The substantially same effect as the connection structure between batteries of each embodiment can be acquired. In addition, since laser welding or beam welding is performed by irradiating the drawn thin portion 78 with the light beam 79, the drawn thin portion 78 is melted before the connection electrode portion 28 and the battery case 14 to form an arc-shaped welded portion. Since sufficient heat is effectively applied, the required welding strength can be ensured and the reliability of welding is improved. In this battery-to-battery connection structure, a similar arc-shaped slit may be provided in place of the narrow-thinned portion 78, and a laser beam or beam welding may be performed by irradiating the slit with a light beam 79. The connection plate 77 may be connected to both the single cells 13 by welding.
[0108]
12 and 13 show a battery module 80 according to still another embodiment of the present invention, FIG. 12 is an exploded perspective view showing a relative arrangement of each component of the battery module 80, and FIG. 13 (a) is a battery. The perspective view which shows the manufacture process of the module 80, the same figure (b) is a perspective view which shows the battery module 80 of an assembly completion state. In the battery module 12 of the embodiment of FIG. 1, the case where a total of 20 single cells 13 are accommodated by arranging two rows of battery rows in which 10 single cells 13 are arranged in a row is illustrated. In the battery module 80 in this embodiment, ten unit cells 13 are arranged and stored in a line.
[0109]
Since this battery module 80 has a configuration substantially equivalent to a configuration in which the battery module 12 of one embodiment is divided into two along the arrangement direction of the single cells 13, the battery module 80 corresponds to the battery module 12 described above. The same reference numerals are assigned, and overlapping description is omitted, and only differences from the battery module 12 will be described below.
[0110]
The unit cell 13 is the same as that described in the above embodiments. The holder case 81 is configured by combining an upper case half 81A and a lower case half 81B, and the case halves 81A and 81B are provided with ten battery storage portions 31 arranged in a row. The upper case half 81A is formed with external connection positive terminals 32 and external connection negative terminals 33 at both ends. The connection plate 38 is the same as that in the embodiment. The elastic sheet 82 has a rectangular shape in plan view equivalent to that obtained by dividing the elastic sheet 36 used in the embodiment into two along the longitudinal direction. The upper lid 83 and the lower lid 84 have a rectangular shape in plan view equivalent to that obtained by dividing the upper lid 53 and the lower lid 54 of the embodiment into two along the longitudinal direction. A heat radiation hole 57 having a shape corresponding to the gap between the partition wall and the unit cell 13 is formed at a location corresponding to the gap.
[0111]
The battery module 80 is assembled into a shape as shown in FIG. 13B by the same assembling procedure as described in the battery module 12 of the embodiment. Since the battery module 80 has substantially the same configuration, only the output voltage is halved compared to the battery module 12 of the embodiment, the same effect can be obtained. As an application, two battery modules 80 are connected to each other via a connecting member 34 to form a battery module unit, and then a required number of battery module units are connected to each other. If it is used as a driving power source for electric bicycles and electric tools for electric power, it is suitable because it is resistant to vibration and impact.
[0112]
【The invention's effect】
As described above, according to the inter-battery connection structure of the present invention, either one of the two unit cells juxtaposed in a layout in which the battery axes are parallel to each other on both sides of the connection plate that is a simple flat plate shape. Because it can be welded in a stable posture supported across the ring-shaped connecting electrode part of the single cell and the bottom of the battery case of the other single cell, there is no risk of problems such as poor bonding, and the yield is greatly increased improves. Moreover, it is only necessary to perform a total of two weldings for joining the connection part and the connection electrode part and between the connection part and the bottom surface of the battery case, and the number of weldings is greatly reduced, and the productivity is remarkably improved. To do. Furthermore, by arranging the single cells in parallel with each other so as to be parallel to the battery axis, the current path between the two single cells is changed between the ring-shaped connection electrode portion of one single cell and the bottom surface of the other single cell. The shortest distance between the outer peripheral portion and a portion close to each other is obtained, and the electrical resistance can be greatly reduced. Further, the connecting plate that spans between each two adjacent unit cells has a substantially bowl shape corresponding to the entire outer shape of the two adjacent unit cells, and does not block the gap between the two unit cells. Therefore, when this inter-electrode connection structure is configured as a battery module, it is possible to effectively configure a heat dissipation passage along the battery axial direction having an equal cross-sectional area around each unit cell. Moreover, although the connection part of a connection board is formed in the small width | variety, it is suppressed that an electrical resistance becomes high with the auxiliary piece provided in the both sides. Moreover, the connection plate has an advantage that the mechanical strength is improved by the auxiliary piece.
[0113]
In addition, according to the battery module of the present invention, since the holder case has a block shape in which the required number of single cells are accommodated, the welding operation of the connecting plate between each two single cells in the next process becomes extremely easy. , Productivity is greatly improved. Further, since the outer dimensions are uniquely determined by the molding accuracy of the holder case made of synthetic resin, there is no dimensional variation and the shape is highly accurate. Furthermore, an insulating ring and a resin outer tube are not required, and material costs can be reduced and productivity can be improved. In addition, since the connection plate has a shape corresponding to the outer shape of the two unit cells, a gap with a uniform cross-sectional area can be formed around the unit cell. And it can cool effectively.
[0114]
In addition, according to the battery pack of the present invention, the battery modules can be configured by easily connecting the battery modules with a simple fixing means using a fixing member, and the battery module unit is fixed to the two exterior plates. By simply fixing with members, it can be easily assembled into a very robust structure and can be manufactured with extremely high productivity.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a relative arrangement of components of a battery module according to an embodiment of the present invention.
2A is a perspective view showing a single cell as a component of the battery module of the above, and FIG. 2B is a cross-sectional view taken along line AA in FIG.
FIGS. 3A and 3B show an inter-battery connection structure according to an embodiment of the present invention applied to connection of single cells in the above battery module, wherein FIG. 3A is a plan view, FIG. 3B is a front view, and FIG. The expanded sectional view cut | disconnected by the BB line of (a).
FIG. 4A is a plan view of a part of a state in which the single cells inserted into the battery housing portion of the holder case in the process of manufacturing the battery module are connected by a connection plate, and FIG. -C line sectional drawing, (c) is the DD line sectional drawing of (a).
5A is a schematic perspective view of a holder case assembling process in the manufacturing process of the battery module of the above, and FIG. 5B is a perspective view of the battery module in a production completed state.
FIG. 6 is a perspective view showing a relative arrangement in a manufacturing process in which three battery module units are configured by using six battery modules as described above.
FIG. 7 is a perspective view showing a manufacturing process for forming a battery pack using the three battery module units of the above.
FIG. 8 is an arrow view seen from the direction P of FIG. 7 in the battery pack according to the embodiment of the present invention configured using the three battery module units same as above.
9A and 9B show a pair of connection plates used in the inter-battery connection structure according to another embodiment of the present invention, where FIG. 9A is a perspective view, FIG. 9B is a plan view, and FIG. 9C is a connection plate. The top view which shows the battery connection structure comprised.
10A and 10B show an inter-battery connection structure according to still another embodiment of the present invention, where FIG. 10A is an exploded perspective view and FIG. 10B is a perspective view.
11A is a plan view showing an inter-battery connection structure according to still another embodiment of the present invention, and FIG. 11B is a cross-sectional view taken along line EE of FIG.
FIG. 12 is an exploded perspective view showing a relative arrangement of components of a battery module according to another embodiment of the present invention.
FIG. 13A is a schematic perspective view showing a manufacturing process of the battery module of the above, and FIG. 13B is a perspective view of the battery module in a manufacturing completed state.
FIG. 14 is a longitudinal sectional view showing a conventional inter-battery connection structure.
FIG. 15 is a perspective view showing a battery module configured using the inter-battery connection structure.
[Explanation of symbols]
12 Battery module
13 cells
14 Battery case
16, 64 fixing screw (fixing member)
18 Sealing body
25,76 Auxiliary piece
28 Connection electrode section
29 recess
30, 81 Holder case
30A, 30B, 81A, 81B Case half
31 Battery compartment
32 Positive terminal for external connection
33 Negative terminal for external connection
34 Connecting members
35, 71 connections
36 Elastic sheet
38, 70, 74, 77 Connection plate
41, 72 connecting part
44 Air gap
45 Mounting member
48 Battery module unit
49 Battery pack
50 exterior plate
51 Busper
52 recess
53, 83, upper lid (lid member)
54,84 Lower lid (lid member)
55 Support rib
56 Holding projection
57 Heat dissipation hole
58, 59 Mounting surface
78 Drawing thin wall

Claims

A battery case having a bottomed cylindrical shape that also serves as one electrode and a sealing body that is closed in an electrically insulated state with respect to the opening of the battery case and also serves as the other electrode. Provided with a plurality of unit cells formed with ring-shaped connection electrode portions protruding outward in the axial direction,
Wherein each cell is juxtaposed in an arrangement, each of the battery axis is parallel Rutotomoni, adjacent unit cells to be connected conductive is disposed so that its orientation is opposite,
A flat connecting plate is placed on the connection electrode part of one of the two adjacent unit cells and the bottom of the battery case of the other unit cell, and the connection It is connected by welding to each of the electrode part and the bottom part of the battery case close to each other,
The connection plate has a pair of connection portions welded to the unit cell having an arc shape capable of including at least the connection electrode portion, and a pair of substantially rectangular shapes having a width smaller than the diameter of the arc shape. And a connecting portion that connects the connecting portions to each other in a plan view that is integrally provided, and includes at least a pair of auxiliary pieces that extend in the orthogonal direction from both sides of the connecting portion, respectively. A battery-to-battery connection structure.

At the center of the bottom part of the battery case, a recess that is recessed inward is formed,
2. The inter-battery connection structure according to claim 1, wherein one connection portion of the connection plate is welded to an adjacent portion of an adjacent unit cell outside the recess in the bottom surface portion of the battery case.

The inter-battery connection structure according to claim 1 or 2, wherein the connection plate is a flat plate integrally formed product made of a three-layer clad material of Ni-Cu-Ni.

The connection plate consists of a pair of identical shapes obtained by dividing the substantially bowl shape into two along the longitudinal direction in plan view,
Each two adjacent unit cells are welded to each side of each of the pair of connection plates that are arranged in close proximity to each other with a small gap, and are electrically connected via these connection plates. The inter-battery connection structure according to any one of claims 1 to 3.

The connecting plate has a thinned portion formed at least at a position close to each other in each contact point with two adjacent unit cells, and the unit cell is subjected to laser welding or beam welding through the thinned portion. The inter-battery connection structure according to claim 1, which is welded to the battery.

The pair of auxiliary pieces extending in the orthogonal direction from both sides along the longitudinal direction of the connecting plate has a length extending from the connecting portion to at least half of the connecting portions on both sides, and the connecting plate has the auxiliary piece The inter-battery connection structure according to any one of claims 1 to 5, wherein the inter-battery connection structure is welded to the two unit cells across the two unit cells adjacent to each other so as to face in a direction opposite to the unit cells.

The pair of auxiliary pieces extending in the orthogonal direction from both sides of the connection plate has a length extending from the connecting portion to at least half of the connection portions on both sides, and each curved end is in contact with the outer surface of the battery case. The inter-battery connection structure according to any one of claims 1 to 5, wherein each of the other end sides is formed in a curved shape in contact with the outer surface of the connection electrode portion.

A plurality of cells having a substantially rectangular parallelepiped outer shape having a thickness approximately half the length in the battery axial direction of the unit cell, and having a rectangular cross section capable of accommodating the cylindrical unit cell therein and penetrating in the thickness direction. A battery housing part is provided with a holder case having a pair of case halves made of synthetic resin formed in a single row arrangement or a plurality of rows arrangement,
In the holder case, the case halves are fixed to each other at a relative position where a plurality of battery storage portions are formed in which the corresponding battery storage portions communicate with each other to store the entire unit cell. And
Each of the single cells individually inserted into each of the storage portions has a holding projection that projects into the battery storage portion from an outer side edge of each of the battery storage portions of the two case halves. Is housed in the battery housing part in a state of being in contact with both end faces of the
Two adjacent single cells are electrically connected to each other and mechanically coupled by the inter-cell connection structure according to any one of claims 1 to 6,
Openings on both sides in the thickness direction of the holder case are respectively closed with lid members fixed to the holder case,
Each of the lid members is formed with a heat radiation hole having a shape corresponding to each of the gaps at a location corresponding to each of the gaps between the unit cell and the four partition walls of the battery housing portion having a square cross section. A battery module characterized by.

9. The battery module according to claim 8, wherein the holder case is formed by coupling both case halves with a rectangular elastic sheet between the opening end faces.

In the battery housing part of the holder case, the width of three of the four first partitions forming a quadrangular cross section is larger than the outer diameter of the unit cell, and the width of the other one second partition is the unit cell. Is formed in a rectangular shape in plan view equal to the outer diameter of each of the first partition walls, and the distance between the respective tips and the distance to the second partition walls are the same as the outer diameter of the unit cell, respectively. The battery module according to claim 8 or 9, wherein three support ribs set to have an equal protruding length are provided.

The three support ribs are integrally provided with holding protrusions that protrude from the outer ends of the support ribs to the inside of the battery storage portion and come into contact with the end surface of the battery case in the battery axial direction. The two holding protrusions that are located in the openings on both sides of each other and face each other are arranged with a separation distance equal to the length between both end faces in the battery axial direction of the unit cell. The battery module as described.

A positive electrode terminal and a negative electrode terminal for external connection are respectively provided by insert molding at one end or both ends in the arrangement direction of the battery housing portion in at least one of the pair of holder cases. Each adjacent unit cell is connected to each other by a connection plate,
The battery module according to any one of claims 8 to 11, wherein connecting members connected to each other by a fixing member are provided on both sides of the two cases in a direction orthogonal to the arrangement direction by insert molding.

In the holder case of the battery module according to any one of claims 8 to 12, a plurality of attachment members are provided by insert molding on both sides along the arrangement direction of the unit cells,
A plurality of battery module units configured to be overlapped at a relative position where the other of the two battery modules is reversed in the thickness direction with respect to one of the two battery modules,
At least two exterior plates covering the periphery of the plurality of battery module units are connected to each other by fixing members respectively inserted into the two mounting members facing each other, and fixed to the battery module. And the two battery modules of each of the battery module units are integrated with the fixing member,
A battery characterized in that a positive electrode terminal and a negative electrode terminal for each external connection of each battery module are electrically connected by a bus bar, and each unit cell built in each battery module is connected in series or in parallel. pack.

At least two exterior plates are formed inside by a plurality of installation surfaces that are brought into contact with the mounting member of the battery module and connected by a fixing member, and each of the installation surfaces bulge outward. A recess and
The battery pack according to claim 13, wherein a heat dissipation passage communicating with the battery housing space of the battery module via a heat dissipation hole of the lid member is formed between the recess and the battery module.