JP3618635B2

JP3618635B2 - Battery protector

Info

Publication number: JP3618635B2
Application number: JP2000124230A
Authority: JP
Inventors: 充明植村
Original assignee: Uchihashi Estec Co Ltd
Current assignee: Uchihashi Estec Co Ltd
Priority date: 2000-04-25
Filing date: 2000-04-25
Publication date: 2005-02-09
Anticipated expiration: 2020-04-25
Also published as: JP2001309551A

Description

【０００１】
【発明の属する技術分野】
本発明は、充放電中の二次電池、特に、リチウムイオン二次電池に対するプロテクタ−に関するものである。
【０００２】
【従来の技術】
充電中のリチウムイオン二次電池等の二次電池の保護方法として、図５に示すように、過充電や過放電により発生する電池Ｅ’の異常電圧を検出回路ＩＣ回路Ｄ’で検出しトランジスタＴｒ’を導通状態にして抵抗体１’に電流を流し、この抵抗体１’の通電発熱でヒュ−ズ素子２’を溶断させて充電源Ｓ’や負荷から遮断することが公知である。
【０００３】
上記のヒュ−ズ素子２’及び抵抗体１’については、図６に示すように絶縁基板４’上に膜電極５１’〜５３’を形成し、膜電極５２’−５３’間に膜抵抗１’を設け、膜電極５１’−５３’間にヒュ−ズ素子２’（低融点可溶合金片）を接続し、この低融点可溶合金片２’にフラックス２１’を塗布し、これらを樹脂で封止した構成、すなわち抵抗体付きヒュ−ズとすることが公知である。
また、上記の二次電池と抵抗体付きヒュ−ズや異常電圧検出回路やトランジスタ等とをまとめて密閉ケ−ス内に収納し、電池パックとすることも公知である。
上記過充電や過放電の電池パックは、通常、廃棄され、ヒュ−ズ素子の溶断時、電池が充電エネルギ−を内蔵しており、旧来では、その電池パックをエネルギ−内蔵のままで廃棄している。
この場合、ヒュ−ズ素子が溶断されたとき電池が満充電状態にあれば、その内蔵エネルギ−が大であり、特にリチウムイオン二次電池においては、エネルギ−密度が高いために、上記電池パックの廃棄中に電池の破裂や液漏れ等が生じ易い。従って、電池の充電中、過充電時にヒュ−ズ素子が溶断されたとき、電池パックをその満充電状態のままで廃棄することは危険である。
【０００４】
そこで、本発明者においては、上記抵抗体付きヒュ−ズに電池放電用の抵抗を付加したプロテクタ−を使用し、前記と同様に、電池異常電圧を検出して発熱用抵抗体に電流を流し、該抵抗体の通電発熱でヒュ−ズ素子を溶断させて回路を遮断したのち、電池の充電エネルギ−を放電用抵抗体を通して放電させることを既に提案した。
この提案によれば、図７において、Ａ’は充放電中の電池Ｅ’の異常時に通電発熱される発熱用素子１’と、該発熱素子１’の発生熱により溶断されるヒュ−ズ素子２１’，２２’と、ヒュ−ズ素子２１’，２２’の溶断により充電源Ｓ’から遮断された電池Ｅ’の貯蔵エネルギ−を所定の時定数で放電するための放電用抵抗素子３’を有するプロテクタ−であり、充電源Ｓ’で充電中の二次電池Ｅ’に異常電圧が発生すると、検出回路Ｄ’の作動でトランジスタＴｒ’が導通され、発熱用抵抗１’の通電発熱によりヒュ−ズ素子２１’，２２’が溶断されて二次電池Ｅ’が充電源Ｓ’より遮断され、次いで、二次電池の貯蔵エネルギ−が放電用抵抗３’を通じて放電されていく。
【０００５】
【発明が解決しようとする課題】
上記において、ヒュ−ズ素子２１’，２２’の溶断温度を余り低くすると、ヒュ−ズ素子がピ−ク負荷電流のもとでのジュ−ル発熱でも溶断される危険があるので、通常ヒュ−ズ素子には溶断温度８０℃〜１５０℃の低融点可溶合金が使用され、ヒュ−ズ素子溶断時のプロテクタ−温度は１２０℃近くであり、相当に高温である。
上記放電中の電池電圧Ｖは、ヒュ−ズ素子溶断時の電池電圧をＶ、回路の静電容量をＣ、放電用抵抗の抵抗値をＲとすると、
【数１】
Ｖ＝Ｖｅ^{￣ｔ／ＣＲ} （１）
で与えられる。
また、放電初期の電池の貯蔵エネルギ−Ｑは
【数２】
Ｑ＝ＣＶ ^２／２（２）
で与えられる。
【０００６】
而るに、放電を短時間で行うと、単位時間当たりの放電量が大きくなって熱発生が顕著となり、この発生熱量がプロテクタ−の放熱量に較べて無視し得ないほど大きくなる結果、上記放電を終了した時点でも、プロテクタ−温度がまだ高く、常温までの冷却には、まだかなりの時間が必要であり、放電を終了しても、直ちに、電池パックを安心して廃棄し難い。
かかる不具合を回避するために放電を緩慢に行うと、長時間を要し、非能率的である。
【０００７】
本発明の目的は、充放電中の電池の異常時に通電発熱される発熱用素子と、該発熱素子の発生熱により回路から遮断された電池の貯蔵エネルギ−を所定の時定数で放電するための放電用抵抗素子を有する電池用プロテクタ−において、発熱用素子の通電発熱によりヒュ−ズ素子が溶断された後の放電用抵抗素子を通じての電池貯蔵エネルギ−放電中でのプロテクタ−の冷却速度を向上させることにより、放電終了時にプロテクタ−を充分に低温にし、放電終了後、直ちに、安心して電池パックを廃棄・放置処理できるようにすることにある。
【０００８】
【課題を解決するための手段】
本発明に係る電池用プロテクタ−は、充放電中の電池の異常時に通電発熱される発熱用素子と、該発熱素子の発生熱により溶断されるヒュ−ズ素子と、ヒュ−ズ素子の溶断により回路から遮断された電池の貯蔵エネルギ−を所定の時定数で放電するための放電用抵抗素子を有し、上記ヒュ−ズ素子が基板の片面に設けられ、該ヒュ−ズ素子にフラックスが塗布され、該フラックス塗布ヒュ−ズ素子が封止材で封止され、上記発熱用素子が基板の他面に設けられ、上記放電用抵抗素子が基板の片面または他面の何れかに設けられていることを特徴とする構成であり、封止材には、（１）封止樹脂、（２）ケ−ス及び該ケ−スと基板との間を封止する樹脂、またはケ−ス及びケ−スを覆ってケ−スと基板との間を封止する樹脂、（３）保護プレ−ト及び保護プレ−トとフラックス塗布ヒュ−ズ素子との間を封止する樹脂、または保護プレ−ト及び保護プレ−トを覆って保護プレ−トとフラックス塗布ヒュ−ズ素子との間を封止する樹脂を使用でき、基板他面側の発熱用素子、または発熱用素子と放電用抵抗素子とは保護膜、例えばガラス焼付け膜で保護できる。
【０００９】
【発明の実施の形態】
以下、図面を参照しつつ本発明の実施の形態について説明する。
図１は、本発明に係るプロテクタ−Ｐを組み込んだ二次電池の充電回路を示し、図中の点線枠内が本発明に係るプロテクタ−部分であり、充放電中の電池の異常時に通電発熱される発熱用素子１と、該発熱素子１の発生熱により溶断されるヒュ−ズ素子２１，２２と、ヒュ−ズ素子２１，２２の溶断により充電源Ｓから遮断された電池Ｅの貯蔵エネルギ−を所定の時定数で放電するための放電用抵抗素子３を有し、上記ヒュ−ズ素子２１，２２が基板の片面に設けられ、該ヒュ−ズ素子にフラックスが塗布され、該フラックス塗布ヒュ−ズ素子が封止材で封止され、上記発熱用素子１が基板の他面に設けられ、上記放電用抵抗素子３が基板の片面または他面の何れかに設けられている。
【００１０】
図１において、Ｅは二次電池、例えばリチウムイオン二次電池である。Ｄは異常電圧検出ＩＣ回路、Ｔｒは異常電圧検出ＩＣ回路Ｄの検出作動により導通状態とされるトランジスタである。Ｓは充電機である。
【００１１】
図１において、過充電により異常電圧が発生すると、この異常電圧を異常電圧検出ＩＣ回路Ｄで検出させ、この検出作動でトランジスタＴｒを導通状態にさせる。
上記発熱用抵抗体１の抵抗値ｒと放電用抵抗体３の抵抗値Ｒとは、ｒ＜Ｒとしてあり（Ｒ／ｒ＞１．１、好ましくはＲ／ｒ＝５〜４０、より好ましくは１０〜３０とされる）、トランジスタＴｒの導通に伴い充電源Ｓの電力で発熱用抵抗体１を通電発熱させ、この発熱でヒュ−ズ素子２１，２２を溶断させる。
このヒュ−ズ素子２１，２２の溶断で電池Ｅと充電源Ｓとの間を遮断させ、この遮断後は電池Ｅの充電エネルギ−を放電用抵抗体３を通じて放電させていく。
【００１２】
この場合、電池電圧Ｖの時間的変化は、電池Ｅの静電容量をＣとすると（ｅ^−ｔ／ ^ＣＲ）で与えられ、電池Ｅの放電速度は時定数１／ＣＲで評価できる。
【００１３】
上記において、ヒュ−ズ素子２１，２２には融点８０℃〜１５０℃の低融点可溶合金が使用され、酸化し易いのでその酸化防止のためにフラックスを塗布し、このフラックス塗布ヒュ−ズ素子を後述のように、樹脂、ケ−ス、保護プレ−ト等により封止して外部の酸素から遮断してある。
而るに、発熱用抵抗１を、上記フラックス塗布ヒュ−ズ素子を設けた基板片面とは反対側の面に設けてあるから、上記ヒュ−ズ素子２１，２２を溶断する温度にまで発熱された発熱用抵抗１の熱を放電時に封止部の高熱抵抗を経ることなく放熱でき、発熱抵抗をヒュ−ズ素子側に設けた場合（従って、封止材で覆って設けた場合）に較べその放熱性を著しくアップできる。
従って、放電中、放電用抵抗体３がジュ−ル発熱するにもかかわらず、プロテクタ−を迅速に放熱でき、放電が終了した時点では、プロテクタ−温度をほぼ常温にでき、放電終了後、直ちに、電池を安心して廃棄できる。
【００１４】
図２の（イ）は本発明に係るプロテクタ−の一実施例を示す断面図である。図２の（ロ）は封止前の平面図を、図２の（ハ）は底面図をそれぞれ示している。図２において、３は耐熱性及び良熱伝導性の絶縁基板である。５１〜５４は基板４の片面側に設けた膜電極、２１，２２はヒュ−ズ素子としての低融点可溶合金片であり膜電極５２−５４−５３にまたがって溶接等により接合してある。６は低融点可溶合金片２１，２２に塗布したフラックスであり、例えばロジンを主成分とするものを使用できる。３は基板片面の膜電極５１−５２間に設けた放電用膜抵抗体（抵抗値Ｒ）である。５５〜５６は基板４の他面側に設けた膜電極、１は膜電極５５−５６間に設けた発熱用膜抵抗体（抵抗値ｒ）、前述した通り、ｒ＜Ｒとしてある。ａ〜ｃは膜電極５１〜５３に溶接などにより接合したリ−ド導体である。
７はスルホ−ルまたはヴィアホ−ルであり、このスルホ−ルまたはヴィアホ−ルにより低融点可溶合金片２１，２２と発熱用膜抵抗１と放電用膜抵抗３とリ−ド導体ａ〜ｃとを図１に示す配線パタ−ンに連結してある。
８１はフラックス塗布低融点可溶合金片に被せたケ−スであり、リ−ド線挿通溝を有し、このケ−ス８１と基板４との間、ケ−ス８とリ−ド線ａ〜ｃとの間を樹脂８２で封止してある。９は基板他面の膜抵抗体１上に設けた保護膜（例えば、膜抵抗体の亀裂防止のための保護）であり、例えば、ガラス焼付け膜を使用することができる。この保護膜は、通常、膜抵抗のトリ−ミング前に設けるが、トリミング後に設けることもできる。この保護膜は、放電用膜抵抗３にも設けることができる。
【００１５】
上記絶縁基板４には、セラミックス基板（例えばアルミナ基板、窒化アルミニウム基板）やガラス基板等の無機質基板、セラミックコ−ティング金属板、セラミック含浸ガラス繊維基板、エポキシ樹脂含浸ガラス繊維基板、紙フエノ−ル基板等を使用できる。
【００１６】
上記膜電極は導電ペ−ストの印刷焼付けにより形成でき、導電ペ−ストには金属粉末とガラスと金属混合物に有機質バインダ（ビヒクル）を加えたものを使用できる。例えば、金属粉末がＡｇ、Ａｇ−Ｐｄ、Ａｇ−Ｐｔの銀系ぺ−スト、Ａｕの金系ペ−スト、Ｎｉのニッケル系ペ−スト、Ｃｕの銅系ペ−スト等を使用できる。この導電ペ−ストの印刷焼付けに代え、めっき法、金属泊積層絶縁板の金属泊のエッチング法の使用も可能である。
【００１７】
上記膜抵抗１１，１２は抵抗ペ−ストの印刷焼付けにより形成でき、抵抗ペ−ストには酸化金属粉末とガラスと金属混合物に有機質バインダ（ビヒクル）を加えたものを使用できる。例えば、酸化金属粉末に酸化ルテニウムを使用したルテニウム系を使用できる。その外、Ａｇ−Ｐｄ、Ａｇ−Ｐｔ等の配合調整により所定の固有抵抗値に調整した銀系ぺ−スト、抵抗粉末に炭素を用いた炭素系ペ−スト、樹脂に金属粉末を混合した樹脂系等も使用できる。また、チップ抵抗をクリ−ムはんだ等で接合したものを用いることもできる。
また、上記放電用抵抗体３には、前記発熱用素子１との抵抗値条件を満たすものであれば、適宜のものを使用でき、高抵抗の回路素子、例えば発光ダイオ−ド等の半導体の使用も可能である。
上記放電用膜抵抗３はヒューズ素子の上または下に絶縁膜を介して積層配設することも可能である。
【００１８】
上記リ−ド線ａ〜ｃには、銅線の外、溶接が容易なニッケル線、リ−ド線の回路基板へのはんだ付け時に熱がヒュ−ズ素子に伝わるのを防止するのに有利な低熱伝導線、例えば鉄線や銅めっき鉄線を使用できる。また、はんだ付けを容易にするためにこれらのリ−ド線に錫、はんだ、銀、金若しくは鉛・カドミフリ−等の金属をめっきすることもできる。
【００１９】
上記ケ−ス８１には、樹脂製例えばナイロンやフェノ−ル製ケ−ス、絶縁被覆金属ケ−ス等を使用できる。また、金属ケ−スを使用し、このケ−スとリ−ド線との間を絶縁物で絶縁すること、例えばエポキシ樹脂塗料をリ−ド線側に塗布することも可能である。ケ−ス８１内には封止剤、例えばエポキシ樹脂を充填することもできるが、低融点可溶合金片２１，２２に塗布したフラックス６が外部と接触するのを防止し得ればよく、ケ−ス８１と基板４との間を樹脂で固着するだけでもよい。
【００２０】
上記基板片面の封止は、フラックス塗布ヒュ−ズ素子を外気から遮断でき、かつ機械的に保護できるものであればよく、フラックス塗布ヒュ−ズ素子上に保護プレ−トを配し、この保護プレ−トの周囲と基板片面やその片面の電極との間を樹脂で封止する構成（保護プレ−ト直下に空隙が残されていてもよく、または樹脂で充填されていてもよい）、更には保護プレ−ト上をも樹脂で覆う構成、或は樹脂のみで封止する構成とすることもできる。。
上記保護プレ−トには、エンジニアリングプラスチックシ−ト、金属板（例えば、ステンレス板）、セラミックス板等の無機質板等を使用できる。
上記樹脂には、エポキシ樹脂等の熱硬化性樹脂、紫外線硬化性樹脂、更には熱か塑性樹脂等を使用できる。
【００２１】
本発明に係るプロテクタ−は異常電圧検出回路や電池とで電池パックに組立て、この電池パックを負荷回路と充電回路を有する機器、例えば携帯式パソコン等に装着して使用できる。
【００２２】
上記実施例では、基板の片面側に放電用抵抗を設けているが、図３〔図３の（イ）は断面図、図３の（ロ）は封止前の平面図、図３の（ハ）は底面図〕に示すように、基板４の他面側に発熱用抵抗１と共に放電用抵抗３を設け、これらの抵抗１，３に保護膜９を一括して設けることもできる。
上記放電用膜抵抗３は発熱用抵抗１の上または下に絶縁膜を介して積層配設することも可能である。
図３において、図２と同一符号は、同一の構成部分を示している。
【００２３】
また、前記図１のｒ’で示すように、例えば、充電回路のインピ−ダンスを調整するために回路抵抗を挿入することもでき、この回路抵抗ｒ’を本発明に係るプロテクタ−に付加することもできる。
更に、チップ方式とすることもできる。
図４の（イ）は回路抵抗を付加したチップ方式の実施例をを示す図面であり、図４の（ロ）同実施例の封止前の平面図を、図４の（ハ）は同実施例の底面図をそれぞれ示している。
図４において、４は耐熱性及び良熱伝導性の絶縁基板である。５１〜５５は基板４の片面に設けた膜電極、５６〜５８は基板４の他面に設けた膜電極は、一部の膜電極は絶縁基板４の両面にわたり形成してある。２１，２２は絶縁基板の片面の膜電極５２−５３−５５にまたがって設けた低融点可溶合金片、１は絶縁基板４の他面に設けた発熱用膜抵抗、３は同じく放電用膜抵抗、ｒ’は同じく回路膜抵抗をそれぞれ示し、スルホ−ルまたはヴィアホ−ル７により低融点可溶合金片２１，２２と発熱用膜抵抗１と放電用膜抵抗３と回路膜抵抗ｒ’を図１に示す配線パタ−ンに連結してある。
６は低融点可溶合金片２１，２２に塗布したフラックスである。
８はフラックス塗布低融点可溶合金片の封止材であり、前記と同様、ケ−ス８１及び該ケ−ス８１と基板４との間を封止する樹脂８２、またはケ−ス及びケ−スを覆ってケ−スと基板との間を封止する樹脂、保護プレ−ト及び保護プレ−トとフラックス塗布ヒュ−ズ素子との間を封止する樹脂、または保護プレ−ト及び保護プレ−トを覆って保護プレ−トとフラックス塗布ヒュ−ズ素子との間を封止する樹脂、または樹脂のみから構成することができる。
９は発熱用膜抵抗１と放電用膜抵抗３と回路膜抵抗ｒ’に一括して被覆した保護膜、例えば、ガラス焼付け膜である。
前記発熱用膜抵抗１、放電用膜抵抗３、回路膜抵抗ｒ’は絶縁膜を介して積層配設することも可能である。
【００２４】
図４に示す実施例では、放電用膜抵抗と回路膜抵抗を基板の他面側（発熱用膜抵抗側）に設けてあるが、放電用膜抵抗または回路膜抵抗の一方、或は双方を基板片面側（低融点可溶合金片側）に設けることもできる。この場合、放電用膜抵抗、回路膜抵抗は低融点可溶合金片の上または下に絶縁膜を介して積層配設することも可能である。
【００２５】
【実施例】
図２に示す構成の抵抗体付きヒュ−ズであり、絶縁基板に縦６ｍｍ，横８ｍｍ，厚み０．３ｍｍのアルミナセラミックス基板（９６％アルミナ）を使用し、膜電極をＡｇ−Ｐｔ系導電ペ−ストの印刷焼き付けにより形成し、膜抵抗を酸化ルテニウム系の抵抗ペ−ストの印刷焼き付けにより設け、発熱用抵抗体の抵抗値をトリミングにより４０Ωに、放電用抵抗体の抵抗値をトリミングにより１０００Ωにそれぞれ調整し、各膜抵抗上にガラス系保護膜を印刷焼き付けにより形成した。さらに、固相線温度１１０℃の断面０．５ｍｍ×０．３ｍｍのヒュ−ズ素子を接続し、このヒュ−ズ素子にロジン系フラックスを滴下塗布し、リ−ド線に錫めっき鉄線を使用し、封止にはナイロンケ−スを用い、このケ−ス絶縁基板との間をエポキシ接着剤で接着した。
この抵抗体付きヒュ−ズに１１．８Ｖの過充電の電池を接続したところ、接続後２０秒でヒュ−ズ素子が溶断した。この溶断時の抵抗体付きヒュ−ズの表面温度は約１２０℃であったが、２４０分で放電が終了し、その時の抵抗体付きヒュ−ズの表面温度はほぼ常温であった。
【００２６】
【発明の効果】
本発明によれば、充電回路及び負荷回路を有しリチウムイオン二次電池等の電池を電源とする機器（特に携帯式機器、例えばノ−トパソコン）において、異常検出によりヒュ−ズ素子が作動して使用不可となった電池パックを機器から、電池の貯蔵エルネギ−を放電させ、かつ、電池パック温度を常温に戻したうえで取外すことができるから、電池パックを安心して廃棄乃至は放置できる。
【図面の簡単な説明】
【図１】本発明に係る電池用プロテクタ−の等価回路図である。
【図２】本発明に係る電池用プロテクタ−の一例を示す図面である。
【図３】本発明に係る電池用プロテクタ−の上記とは別の例を示す図面である。
【図４】本発明に係る電池用プロテクタ−の上記とは別の例を示す図面である。
【図５】従来の電池用プロテクタ−の等価回路図である。
【図６】従来の電池用プロテクタ−を示す図面である。
【図７】従来の上記とは別の従来の電池用プロテクタ−の等価回路図である。
【符号の説明】
１発熱用素子
２１ヒュ−ズ素子
２２ヒュ−ズ素子
３放電用抵抗素子
４基板
６フラックス
８１ケ−ス
８２樹脂
９保護膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a protector for a secondary battery during charging and discharging, in particular, a lithium ion secondary battery.
[0002]
[Prior art]
As a method for protecting a secondary battery such as a lithium ion secondary battery during charging, as shown in FIG. 5, an abnormal voltage of the battery E ′ generated by overcharging or overdischarging is detected by a detection circuit IC circuit D ′. It is known that a current is passed through the resistor 1 ′ with Tr ′ in a conducting state, and the fuse element 2 ′ is blown by the energization heat generated by the resistor 1 ′ to cut off from the charging source S ′ or load.
[0003]
For the fuse element 2 ′ and the resistor 1 ′, as shown in FIG. 6, film electrodes 51 ′ to 53 ′ are formed on the insulating substrate 4 ′, and film resistance is formed between the film electrodes 52 ′ to 53 ′. 1 ', a fuse element 2' (low melting point soluble alloy piece) is connected between the membrane electrodes 51'-53 ', and flux 21' is applied to the low melting point soluble alloy piece 2 '. It is known that a resin is sealed with a resin, that is, a fuse with a resistor.
It is also known that the above secondary battery, a fuse with a resistor, an abnormal voltage detection circuit, a transistor, and the like are collectively housed in a sealed case to form a battery pack.
The above overcharged or overdischarged battery pack is usually discarded, and when the fuse element is blown, the battery has built-in charging energy. Traditionally, the battery pack is discarded with the built-in energy. ing.
In this case, if the battery is in a fully charged state when the fuse element is melted, the built-in energy is large. In particular, in a lithium ion secondary battery, the energy density is high. The battery is likely to rupture, leak, etc. during disposal. Therefore, when the fuse element is blown during overcharging during battery charging, it is dangerous to discard the battery pack in its fully charged state.
[0004]
Therefore, the present inventor uses a protector in which a resistor for discharging the battery is added to the fuse with the resistor, and detects a battery abnormal voltage and sends a current to the heating resistor in the same manner as described above. It has already been proposed to discharge the charging energy of the battery through the discharging resistor after the fuse element is blown by the energization heat generation of the resistor to cut off the circuit.
According to this proposal, in FIG. 7, A ′ is a heating element 1 ′ that generates heat when the battery E ′ being charged / discharged is abnormal, and a fuse element that is blown by heat generated by the heating element 1 ′. 21 ', 22' and discharging resistance element 3 'for discharging the storage energy of battery E' cut off from charging source S 'by fusing fuse elements 21', 22 'with a predetermined time constant When an abnormal voltage is generated in the secondary battery E ′ that is being charged by the charging source S ′, the transistor Tr ′ is turned on by the operation of the detection circuit D ′, and the heating resistor 1 ′ is energized to generate heat. The fuse elements 21 ′ and 22 ′ are melted to disconnect the secondary battery E ′ from the charging source S ′, and then the stored energy of the secondary battery is discharged through the discharging resistor 3 ′.
[0005]
[Problems to be solved by the invention]
In the above description, if the fusing temperature of the fuse elements 21 'and 22' is too low, the fuse element may be blown even by heat generation under peak load current. A low melting point soluble alloy having a fusing temperature of 80 ° C. to 150 ° C. is used for the fuse element, and the protector temperature at the time of fusing the fuse element is close to 120 ° C., which is considerably high.
The battery voltage V during the discharge is expressed as follows: V is the battery voltage when the fuse element is blown, C is the capacitance of the circuit, and R is the resistance value of the discharging resistor.
[Expression 1]
V = V e ^{￣t / CR} (1)
Given in.
In addition, the storage energy Q of the battery at the initial stage of discharge is
^{Q = CV 2/2 (2} )
Given in.
[0006]
Therefore, when the discharge is performed in a short time, the amount of discharge per unit time becomes large and the heat generation becomes remarkable, and the amount of generated heat becomes so large that it cannot be ignored compared with the heat dissipation amount of the protector. Even when the discharge is finished, the protector temperature is still high, and a considerable amount of time is still required for cooling to room temperature. Even after the discharge is finished, it is difficult to immediately dispose of the battery pack with peace of mind.
If discharge is performed slowly in order to avoid such a problem, it takes a long time and is inefficient.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to discharge a heat generating element that is energized and heated when a battery is abnormal during charge and discharge, and the stored energy of the battery that is cut off from the circuit by heat generated by the heat generating element with a predetermined time constant. In battery protectors having a discharge resistance element, the cooling rate of the protector during battery storage energy discharge through the discharge resistance element after the fuse element is melted by the heat generation of the heating element is improved. Thus, the protector is made sufficiently low at the end of the discharge, and immediately after the end of the discharge, the battery pack can be disposed of and left undisturbed safely.
[0008]
[Means for Solving the Problems]
The battery protector according to the present invention includes a heat generating element that is energized and heated when the battery is abnormal during charging and discharging, a fuse element that is melted by heat generated by the heat generating element, and a fuse element that is fused. A discharge resistive element for discharging the stored energy of the battery disconnected from the circuit at a predetermined time constant, the fuse element is provided on one side of the substrate, and a flux is applied to the fuse element; The flux application fuse element is sealed with a sealing material, the heating element is provided on the other side of the substrate, and the discharge resistance element is provided on one side or the other side of the substrate. The sealing material includes (1) a sealing resin, (2) a case and a resin that seals between the case and the substrate, or a case and Resin that covers the case and seals between the case and the substrate, (3) protective plate And a resin that seals between the protective plate and the flux application fuse element, or covers the protection plate and the protection plate and seals between the protection plate and the flux application fuse element. Resin can be used, and the heating element on the other side of the substrate, or the heating element and the discharge resistance element can be protected by a protective film, for example, a glass baking film.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a charging circuit for a secondary battery incorporating the protector P according to the present invention, and the inside of the dotted line frame in the figure is the protector portion according to the present invention. Stored in the battery E which is cut off from the charging source S by the fusing of the heat generating element 1, the fuse elements 21 and 22 fused by the heat generated by the heat generating element 1, and the fuse elements 21 and 22. A discharge resistance element 3 for discharging at a predetermined time constant, the fuse elements 21 and 22 are provided on one side of the substrate, a flux is applied to the fuse element, and the flux application The fuse element is sealed with a sealing material, the heat generating element 1 is provided on the other side of the substrate, and the discharge resistance element 3 is provided on one side or the other side of the substrate.
[0010]
In FIG. 1, E is a secondary battery, for example, a lithium ion secondary battery. D is an abnormal voltage detection IC circuit, and Tr is a transistor that is rendered conductive by the detection operation of the abnormal voltage detection IC circuit D. S is a charger.
[0011]
In FIG. 1, when an abnormal voltage occurs due to overcharging, the abnormal voltage is detected by the abnormal voltage detection IC circuit D, and the transistor Tr is turned on by this detection operation.
The resistance value r of the heating resistor 1 and the resistance value R of the discharging resistor 3 are r <R (R / r> 1.1, preferably R / r = 5 to 40, more preferably When the transistor Tr is turned on, the heating resistor 1 is energized and heated by the power of the charging source S, and the fuse elements 21 and 22 are melted by this heat generation.
The fuse elements 21 and 22 are disconnected to cut off the battery E and the charging source S. After the interruption, the charging energy of the battery E is discharged through the discharge resistor 3.
[0012]
In this case, the time change of the battery voltage V is given by (e ^{−t /} ^CR ) where C is the capacitance of the battery E, and the discharge rate of the battery E can be evaluated by the time constant 1 / CR.
[0013]
In the above, the fuse elements 21 and 22 are made of a low melting point soluble alloy having a melting point of 80 ° C. to 150 ° C., and are easily oxidized. Therefore, a flux is applied to prevent the oxidation. As will be described later, this is sealed with a resin, a case, a protective plate or the like and shielded from external oxygen.
Accordingly, since the heating resistor 1 is provided on the surface opposite to the one surface of the substrate on which the flux application fuse element is provided, the heat generation resistance 1 is heated to a temperature at which the fuse elements 21 and 22 are fused. The heat of the heating resistor 1 can be dissipated without passing through the high thermal resistance of the sealing part at the time of discharge, and compared with the case where the heating resistor is provided on the fuse element side (thus, when it is covered with a sealing material). The heat dissipation can be remarkably improved.
Accordingly, the protector can quickly dissipate heat even though the discharge resistor 3 generates heat during discharge, and at the time when the discharge is completed, the protector temperature can be brought to almost normal temperature. Battery can be disposed of safely.
[0014]
FIG. 2A is a sectional view showing an embodiment of the protector according to the present invention. 2B is a plan view before sealing, and FIG. 2C is a bottom view. In FIG. 2, reference numeral 3 denotes an insulating substrate having heat resistance and good thermal conductivity. Reference numerals 51 to 54 denote membrane electrodes provided on one side of the substrate 4, and reference numerals 21 and 22 denote low melting point soluble alloy pieces as fuse elements, which are joined by welding or the like across the membrane electrodes 52-54-53. . Reference numeral 6 denotes a flux applied to the low melting point soluble alloy pieces 21 and 22, and for example, a flux mainly composed of rosin can be used. Reference numeral 3 denotes a discharge film resistor (resistance value R) provided between the film electrodes 51-52 on one side of the substrate. 55 to 56 are film electrodes provided on the other side of the substrate 4, 1 is a heating film resistor (resistance value r) provided between the film electrodes 55 to 56, and r <R as described above. A to c are lead conductors joined to the membrane electrodes 51 to 53 by welding or the like.
Reference numeral 7 denotes a sulfole or via hole. By this sulfole or via hole, the low melting point soluble alloy pieces 21 and 22, the heat generating film resistor 1, the discharge film resistor 3, and the lead conductors a to c are formed. Are connected to the wiring pattern shown in FIG.
Reference numeral 81 denotes a case placed on the flux-coated low melting point soluble alloy piece and has a lead wire insertion groove. Between the case 81 and the substrate 4, the case 8 and the lead wire are provided. A space between a and c is sealed with a resin 82. Reference numeral 9 denotes a protective film (for example, protection for preventing cracking of the film resistor) provided on the film resistor 1 on the other surface of the substrate. For example, a glass baking film can be used. This protective film is usually provided before trimming of the film resistance, but can also be provided after trimming. This protective film can also be provided on the discharge film resistor 3.
[0015]
The insulating substrate 4 includes an inorganic substrate such as a ceramic substrate (for example, an alumina substrate or an aluminum nitride substrate) or a glass substrate, a ceramic coating metal plate, a ceramic-impregnated glass fiber substrate, an epoxy resin-impregnated glass fiber substrate, or paper phenol. A substrate or the like can be used.
[0016]
The membrane electrode can be formed by printing and baking a conductive paste, and the conductive paste can be obtained by adding an organic binder (vehicle) to a metal powder, glass and a metal mixture. For example, Ag, Ag-Pd, Ag-Pt silver paste, Au gold paste, Ni nickel paste, Cu copper paste, etc. can be used. Instead of the printing paste of the conductive paste, it is also possible to use a plating method or a metal stay etching method for a metal stay laminated insulating plate.
[0017]
The film resistors 11 and 12 can be formed by printing and baking a resistance paste. The resistance paste can be obtained by adding an organic binder (vehicle) to a metal oxide powder, glass and a metal mixture. For example, a ruthenium system using ruthenium oxide as the metal oxide powder can be used. In addition, a silver-based paste adjusted to a predetermined specific resistance value by adjusting the composition of Ag-Pd, Ag-Pt, etc., a carbon-based paste using carbon as a resistance powder, and a resin in which a metal powder is mixed with a resin Systems can also be used. Further, a chip resistor joined with cream solder or the like can also be used.
The discharge resistor 3 may be any appropriate one as long as it satisfies the resistance value with respect to the heat generating element 1, and may be a high resistance circuit element such as a semiconductor such as a light emitting diode. Use is also possible.
The discharge film resistor 3 may be laminated on or below the fuse element via an insulating film.
[0018]
The lead wires a to c are advantageous in preventing heat from being transferred to the fuse element when soldering a nickel wire, which is easily welded, or a lead wire to a circuit board in addition to a copper wire. A low heat conductive wire such as an iron wire or a copper-plated iron wire can be used. In order to facilitate soldering, these lead wires can be plated with a metal such as tin, solder, silver, gold or lead / cadmium free.
[0019]
The case 81 may be made of resin, for example, nylon or phenol case, insulating coating metal case, or the like. It is also possible to use a metal case and insulate between the case and the lead wire with an insulator, for example, an epoxy resin paint can be applied to the lead wire side. The case 81 can be filled with a sealing agent, for example, an epoxy resin, as long as the flux 6 applied to the low melting point soluble alloy pieces 21 and 22 can be prevented from coming into contact with the outside. The case 81 and the substrate 4 may be simply fixed with resin.
[0020]
The sealing on one side of the substrate is not limited as long as the flux application fuse element can be shielded from the outside air and can be mechanically protected. A protective plate is provided on the flux application fuse element to protect this element. A structure in which the space between the periphery of the plate and one side of the substrate or the electrode on the one side is sealed with a resin (a space may be left directly under the protective plate, or it may be filled with a resin), Further, the protective plate may be covered with resin, or may be sealed with resin alone. .
As the protective plate, an engineering plastic sheet, a metal plate (for example, a stainless steel plate), an inorganic plate such as a ceramic plate, or the like can be used.
As the resin, a thermosetting resin such as an epoxy resin, an ultraviolet curable resin, or a heat or plastic resin can be used.
[0021]
The protector according to the present invention can be used by assembling a battery pack with an abnormal voltage detection circuit and a battery, and mounting the battery pack on a device having a load circuit and a charging circuit, such as a portable personal computer.
[0022]
In the above embodiment, the discharge resistor is provided on one side of the substrate. FIG. 3 [FIG. 3 (A) is a sectional view, FIG. 3 (B) is a plan view before sealing, FIG. As shown in the bottom view], a discharge resistor 3 can be provided together with a heating resistor 1 on the other side of the substrate 4, and a protective film 9 can be collectively provided on these resistors 1 and 3.
The discharge film resistor 3 can be laminated on or below the heat generating resistor 1 via an insulating film.
3, the same reference numerals as those in FIG. 2 denote the same components.
[0023]
Further, as indicated by r ′ in FIG. 1, for example, a circuit resistor can be inserted in order to adjust the impedance of the charging circuit, and this circuit resistor r ′ is added to the protector according to the present invention. You can also
Further, a chip system can be used.
4 (a) is a drawing showing an embodiment of a chip system to which circuit resistance is added. FIG. 4 (b) is a plan view of the embodiment before sealing, and FIG. The bottom view of an Example is shown, respectively.
In FIG. 4, 4 is an insulating substrate having heat resistance and good thermal conductivity. 51 to 55 are film electrodes provided on one surface of the substrate 4, 56 to 58 are film electrodes provided on the other surface of the substrate 4, and some film electrodes are formed on both surfaces of the insulating substrate 4. 21 and 22 are low melting point soluble alloy pieces provided across the film electrodes 52-53-55 on one side of the insulating substrate, 1 is a heating film resistor provided on the other side of the insulating substrate 4, and 3 is a discharge film. The resistance r ′ similarly represents a circuit film resistance, and the low melting point soluble alloy pieces 21, 22, the heating film resistance 1, the discharge film resistance 3, and the circuit film resistance r ′ are respectively represented by sulfole or via hole 7. It is connected to the wiring pattern shown in FIG.
Reference numeral 6 denotes a flux applied to the low melting point soluble alloy pieces 21 and 22.
8 is a sealing material for the flux-coated low-melting-point soluble alloy piece. Similarly to the above, the case 81 and the resin 82 for sealing the case 81 and the substrate 4 or the case and the case are sealed. A resin covering the case and sealing between the case and the substrate, a protective plate and a resin sealing between the protective plate and the flux coating fuse element, or a protective plate and It can be made of a resin that covers the protective plate and seals between the protective plate and the flux application fuse element, or a resin alone.
Reference numeral 9 denotes a protective film, for example, a glass baking film, which covers the heat generating film resistor 1, the discharge film resistor 3, and the circuit film resistor r 'collectively.
The heat generating film resistor 1, the discharge film resistor 3, and the circuit film resistor r ′ can be laminated by an insulating film.
[0024]
In the embodiment shown in FIG. 4, the discharge film resistance and the circuit film resistance are provided on the other side of the substrate (the heat generation film resistance side), but either or both of the discharge film resistance and the circuit film resistance are provided. It can also be provided on one side of the substrate (one side of the low melting point soluble alloy). In this case, the discharge film resistance and the circuit film resistance can be laminated on or below the low melting point soluble alloy piece via an insulating film.
[0025]
【Example】
2 is a fuse with a resistor having a structure shown in FIG. 2. An insulating substrate is an alumina ceramic substrate (96% alumina) having a length of 6 mm, a width of 8 mm, and a thickness of 0.3 mm. -Formed by printing and baking strikes, and providing film resistance by printing and baking ruthenium oxide-based resistance paste. The resistance value of the heating resistor is trimmed to 40Ω, and the resistance value of the discharging resistor is trimmed to 1000Ω. And a glass-based protective film was formed on each film resistor by printing and printing. Furthermore, a fuse element having a cross-section of 0.5 mm × 0.3 mm with a solidus temperature of 110 ° C. is connected, and a rosin-based flux is dropped onto this fuse element, and a tin-plated iron wire is used as the lead wire. Then, a nylon case was used for sealing, and the case insulating substrate was bonded with an epoxy adhesive.
When a 11.8 V overcharged battery was connected to the fuse with resistor, the fuse element was blown out 20 seconds after the connection. The surface temperature of the fuse with a resistor at the time of this fusing was about 120 ° C., but the discharge was completed in 240 minutes, and the surface temperature of the fuse with a resistor at that time was approximately room temperature.
[0026]
【The invention's effect】
According to the present invention, in a device having a charging circuit and a load circuit and using a battery such as a lithium ion secondary battery as a power source (particularly a portable device such as a notebook personal computer), the fuse element is activated by detecting an abnormality. The battery pack that has become unusable can be removed from the device by discharging the storage energy of the battery and returning the battery pack temperature to room temperature, so that the battery pack can be safely discarded or left unattended.
[Brief description of the drawings]
FIG. 1 is an equivalent circuit diagram of a battery protector according to the present invention.
FIG. 2 is a view showing an example of a battery protector according to the present invention.
FIG. 3 is a drawing showing another example of the battery protector according to the present invention.
FIG. 4 is a drawing showing another example of the battery protector according to the present invention different from the above.
FIG. 5 is an equivalent circuit diagram of a conventional battery protector.
FIG. 6 is a diagram showing a conventional battery protector.
FIG. 7 is an equivalent circuit diagram of a conventional battery protector different from the conventional one described above.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heating element 21 Fuse element 22 Fuse element 3 Discharge resistance element 4 Substrate 6 Flux 81 Case 82 Resin 9 Protective film

Claims

A heating element that is energized and heated when a battery abnormality occurs during charging / discharging, a fuse element that is blown by heat generated by the heating element, and a storage energy of the battery that is cut off from the circuit by the fusing of the fuse element A discharge resistance element for discharging the battery at a predetermined time constant, the fuse element is provided on one side of the substrate, and a flux is applied to the fuse element, and the flux application fuse element Is sealed with a sealing material, the heating element is provided on the other side of the substrate, and the discharge resistance element is provided on one side or the other side of the substrate. -.

The battery protector according to claim 1, wherein the sealing material is a resin.

The sealing material includes a case and a resin that seals between the case and the substrate, or a resin that covers the case and the case and seals between the case and the substrate. The battery protector according to claim 1.

A sealing material covers the protective plate and the resin that seals between the protective plate and the flux application fuse element, or covers the protective plate and the protective plate and applies the protective plate and the flux. The battery protector according to claim 1, comprising a resin that seals between the fuse elements.

The battery protector according to any one of claims 1 to 4, wherein the heating element on the other side of the substrate, or the heating element and the discharge resistance element are covered with a protective film.

The battery protector according to claim 5, wherein the protective film is a glass baking film.

The battery protector according to claim 1, wherein a circuit resistor inserted in series with the battery is attached to the substrate.