JP4016668B2

JP4016668B2 - Fuel cell system and fuel cell vehicle

Info

Publication number: JP4016668B2
Application number: JP2002039893A
Authority: JP
Inventors: 寿弘竹川; 篤史宮澤
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2002-02-18
Filing date: 2002-02-18
Publication date: 2007-12-05
Anticipated expiration: 2022-02-18
Also published as: JP2003243013A

Description

【０００１】
【発明の属する技術分野】
本発明は、固体高分子膜を電解質として用いた固体高分子電解質型燃料電池を備える固体高分子電解質型燃料電池発電システムに係り、特に寒冷地での使用を可能にする始動性向上の技術に関するものである。
【０００２】
【従来の技術】
一般に、燃料電池は、反応ガスである水素などの燃料ガスと空気などの酸化剤ガスを電気化学的に反応させることにより、燃料の持つ化学エネルギーを直接電気エネルギーに変換する装置である。この燃料電池は、電解質の違いなどによりさまざまなタイプのものに分類されるが、その一つとして、電解質に固体高分子電解質を用いる固体高分子電解質型燃料電池が知られている。
【０００３】
このときの燃料極、酸化剤極の両電極において進行する電極反応は、以下の反応式の通りである。
【０００４】
燃料（アノード）極：２Ｈ_２→４Ｈ^＋＋４ｅ⁻ …(１)
酸化剤（カソード）極：４Ｈ^＋＋４ｅ⁻＋Ｏ_２→２Ｈ_２Ｏ …(２)
そして、燃料極に水素ガスが供給されると、燃料極では(１)の反応式が進行して水素イオンが生成する。この生成した水素イオンが水和状態で固体高分子電解質膜を透過（拡散）して酸化剤極に至り、この酸化剤極に供給される酸素含有ガス、例えば空気中の酸素を伴って、(２)の反応式が進行する。この(１)、(２)の電極反応が各極で進行することで、燃料電池は起電力を生じることとなる。
【０００５】
この燃料電池での発電では、燃料の持つ化学エネルギーのうち電気エネルギーに変換できない分を熱として放出する。当該反応を円滑に進行させるため放出された熱を冷却する必要があるが、自然冷却だけでは冷却力が小さいので、循環する冷却水で強制的に燃料電池を冷却することが広く行われている(例えば、特開平５−１９０１９３号公報)。
【０００６】
【発明が解決しようとする課題】
固体高分子電解質型燃料電池においては、高分子電解質膜のプロトン導電性が反応ガスの湿度に著しく依存するので、反応ガスの湿度が低すぎると、高分子電解質膜が乾燥して膜抵抗が増大し、燃料電池発電特性の低下を引き起こすこととなる。このため、一般的には電極の湿潤状態を適切に保持するために、反応ガスを加湿器等の加湿手段により加湿して供給する方式が検討されている。しかし、ガス流路や膜電極接合体付近の水分量が多くなると、凝縮した水が電極や拡散層の細孔に浸透する、いわゆる“電極の濡れ＝フラッディング“が生じ、ガス拡散性が低下して発電特性の低下を引き起こす恐れがある。
【０００７】
また、上記の式（２）に示されるように、カソード極では発電に際して水が生成するため、更にフラッディングが生じやすく、“電極の濡れ＝フラッディング”を発生させないための制御も必要となる。
【０００８】
このため、反応ガスを加湿しないで固体高分子電解質形燃料電池を運転する無加湿運転が試みられており、例えば高分子電解質膜を薄膜化する方法、あるいはアノードとカソードに供給する反応ガスを互いに反対方向に流通させる、いわゆる対向流とする方法等が試みられている（たとえば特開２００１−１８５１７２号公報や特開２００１−６６９８号公報）。
しかしながら、供給するガスへの外部からの加湿をいくら抑制しても、式（２）に見られるように上記の反応においてはカソード極で水が生成するので、燃料電池の運転停止時にはガス流路内に気液混合物が残存することとなる。冬期の寒冷地等のような低温となる場所で使用した場合、この残存する水が運転停止中に凍結することがあるので、次の起動の際にはこれらの凍結物がガスの流通の妨げとなり、速やかに燃料電池システムを起動することが困難になる。特に、高分子電解質形燃料電池の発電効率が望ましい６０℃〜９０℃の運転温度へ急速に上げることは困難であった。
【０００９】
このため、寒冷地での停止した燃料電池の運転始動においては、燃料電池を所定の温度まで暖める試みが多くなされている（たとえば、電気ヒーターで加温を行う方法（特開平７−２９５８５）、バーナーを用いる方法（特開平８−１６２１３７）など）。
【００１０】
ところが、燃料電池を外部から暖める場合は、加温に必要な手段を別に備えることを必要とするため燃料電池システムが大きくなってしまい、例えば空間の限られた燃料電池自動車へ搭載するレイアウトに制限を及ぼしてしまう。
【００１１】
このため、外部に加温装置を備えずに燃料電池を加温する方法として、低温時から燃料電池の運転を行って、自己発電で発生する熱を利用する試みもなされている（ＦＹ２０００ＰｒｏｇｒｅｓｓＲｅｐｏｒｔＰ．８５ “Ｃｏｌｄ−ＳｔａｒｔＤｙｎａｍｉｃｓｏｆａＰＥＭＦｕｅｌＣｅｌｌＳｔａｃｋ．”）。
【００１２】
しかしながら、氷点下以下での燃料電池の発電を試みる場合、式（２）に記したように稼動時にはカソードで水が発生するため、この生成水がガス流路で凍結してガス流通を妨げてしまい、結果として発電を困難にしてしまうことがある。
【００１３】
本発明は、上記の如き現状の課題を考慮してなされたもので、その目的は、寒冷地で使用したとしても速やかに起動することができる燃料電池システムを提供することにある。
【００１４】
【課題を解決するための手段】
第１の発明は、水素イオン透過性の固体高分子電解質膜と、この固体高分子電解質膜を狭持する電極と、この電極に発電に供せられるガスを接するように流通させる流路を形成したセパレータとからなる燃料電池を備えた燃料電池システムにおいて、前記流路は、ガスが流入する第１導入口とガスが排出する第１排出口とを備えた流路断面積の大きな大流路と、この大流路の流路途中に連通し、大流路の流路断面積より小さい流路断面積で形成される小流路とからなり、前記小流路は、ガスが流入する第２導入口またはガスが排出される第２排出口とを備え、前記大流路と前記小流路へのガスの流量を制御し、発電領域を制御する第１制御弁を設け、燃料電池の温度に応じて前記第１制御弁を制御し、氷点下からの燃料電池システムの起動時に、前記大流路にガスを流通させて大流路域で発電を生じさせ、発電に伴う熱により燃料電池を解凍及び昇温し、燃料電池が所定温度以上の時に前記小流路にガスを流通させ、小流路域で発電する。
【００１５】
第２の発明は、水素イオン透過性の固体高分子電解質膜と、この固体高分子電解質膜を狭持する電極と、この電極に発電に供せられるガスを接するように流通させる流路を形成したセパレータとからなる燃料電池を備えた燃料電池システムにおいて、前記流路は、ガスが流入する第１導入口とガスが排出する第１排出口とを備えた流路断面積の大きな大流路と、この大流路の流路途中に連通し、大流路の流路断面積より小さい流路断面積で形成される小流路とからなり、前記小流路は、ガスが流入する第２導入口またはガスが排出される第２排出口とを備え、前記大流路と前記小流路へのそれぞれのガスの流量を制御し、発電領域を制御する第１制御弁を設け、燃料電池の温度に応じて前記第１制御弁を制御し、氷点下からの燃料電池システムの起動時に、前記大流路にガスを流通させて大流路域で発電を生じさせ、発電に伴う熱により燃料電池を解凍及び昇温し、燃料電池が所定温度以上の時に前記小流路にガスを流通させ、小流路域で発電する。
【００１６】
第３の発明は、第１または２の発明において、前記小流路は、前記大流路から前記ガスが導入されるように連通されるとともに前記第２排出口を備え、前記第１制御弁は、前記大流路の第１排出口下流に設けられる。
【００１７】
第４の発明は、第１または２の発明において、前記小流路は、前記第２導入口を備えるとともに前記大流路に前記ガスを導入するように連通し、前記第１制御弁は、前記大流路の第１導入口上流に設けられる。
【００１８】
第５の発明は、水素イオン透過性の固体高分子電解質膜と、この固体高分子電解質膜を狭持する電極と、この電極に発電に供せられるガスを接するように流通させる流路を形成したセパレータとからなる燃料電池を備えた燃料電池システムにおいて、前記流路は、流路断面積の大きな大流路と、この大流路の流路途中で連通し、前記大流路の流路断面積より小さい流路断面積で形成される小流路とからなるとともに、前記流路は、複数の前記大流路とこれら大流路間を連通する前記小流路とから構成され、少なくとも前記大流路の１つは、ガスが流入する第３導入口とガスが排出される第３排出口とを備え、他の前記大流路は、ガスが排出される第４排出口を備え、前記第３導入口と第３排出口とを備えた前記大流路の下流にガスの流量を制御する第１制御弁を設け、燃料電池の温度に応じて前記第１制御弁を制御し、氷点下からの燃料電池システムの起動時に、前記大流路にガスを流通させて大流路域で発電を生じさせ、発電に伴う熱により燃料電池を解凍及び昇温し、燃料電池が所定温度以上の時に前記小流路にガスを流通させ、小流路域で発電する。
【００２３】
第６の発明は、第１から５のいずれか一つの発明において、前記大流路を前記電極面の内側に配置し、その両側に前記小流路を形成した。
【００２４】
第７の発明は、第１から６のいずれか一つの発明において、前記小流路のガス流量を制御する第２制御弁を備える。
【００２５】
第８の発明は、第１から７のいずれか一つの発明において、前記固体高分子電解質膜に対峙する２つの電極のそれぞれの電極側でガス流れ方向が逆向きである。
【００２６】
第９の発明は、第１から８のいずれか一つの発明において、前記小流路のガス流れ方向に対して上流部と下流部に前記大流路を形成し、小流路の上流部と下流部で大流路と連通した。
【００２７】
第１０の発明は、第７の発明において、前記第１、第２制御弁を制御するコントローラを備え、このコントローラは、前記第１制御弁を開放し、大流路に直接ガスを導入かつ排出する経路を構成するステップと、前記第２制御弁を閉じて小流路のガス流入を遮蔽するステップと、前記大流路にガスを供給するステップと、燃料電池の温度を検出するステップと、検出温度と燃料電池の発電と温度との特性に基づいて設定された設定温度を比較するステップと、検出温度が設定温度以上のときにガスを小流路に供給するように第１、第２制御弁を制御するステップとからなるプログラムを記憶したことを特徴とする。
【００２８】
第１１の発明は、第７の発明において、前記第１、第２制御弁を制御するコントローラを備え、このコントローラは、前記第１制御弁を開放し、大流路に直接ガスを導入かつ排出する経路を構成するステップと、前記第２制御弁を閉じて小流路のガス流入を遮蔽するステップと、前記大流路にガスを供給するステップと、燃料電池の温度を検出するステップと、検出温度と燃料電池の発電と温度との特性に基づいて設定された設定温度を比較するステップと、検出温度が設定温度以上のときに固体高分子電解質膜に対峙する２つの電極のそれぞれの電極側でガス流れ方向を逆向きとしてガスを小流路に供給するステップとからなるプログラムを記憶したことを特徴とする。
【００２９】
第１２の発明は、第７から１１のいずれか一つの発明において、前記コントローラは、前記燃料電池からの電力の供給を停止するステップと、電力供給停止後小流路にガスを供給するステップと、小流路へのガスの供給を停止し、大流路へ直接ガスを供給し、排出されるように第１、２制御弁を制御するステップと、大流路へのガスを停止するステップとからなるプログラムを記憶したことを特徴とする。
【００３１】
第１３の発明は、第１から１２のいずれか一つの発明において、発電のために供給されるガスの一部は、低湿度状態で供給されることを特徴とする。
【００３２】
第１４の発明は、第１から１３のいずれか一つの発明において、発電のために供給されるガスの一部は、外部で加湿されることなく供給されることを特徴とする。
【００３３】
第１５の発明は、水素イオン透過性の固体高分子電解質膜と、この固体高分子電解質膜を狭持する電極と、この電極に発電に供せられるガスを接するように流通させる流路を形成したセパレータとからなる燃料電池を備えた燃料電池車両において、セパレータに形成されたガスが流通する流路は、ガスが流入してから排出されるまでを通じて流路断面積の大きな大流路と、この大流路に連通する大流路の断面積より小さい断面積で形成される小流路とからなり、大流路と小流路には、それぞれの流路の流量を制御する第１、第２制御弁が設けられ、燃料電池の温度に応じて第１、第２制御弁を制御し、氷点下からの燃料電池システムの起動時に、大流路にガスを流通させて大流路域で発電を生じさせ、発電に伴う熱により燃料電池を解凍及び昇温し、燃料電池が所定温度以上の時に小流路にガスを流通させ、小流路域で発電する。
【００３４】
【発明の効果】
第１または２の発明は、ガスが流入してから排出されるまでを通して流路断面積が大きな流路（大流路）をセパレータに構成したので、流路内の水分が凍結するような低温度においても流路の閉塞を大流路によって避けることができる。従って低温環境においても大流路による発電を継続することができ、自己発熱による燃料電池の昇温を確実に得られるようになる。一方、凍結の恐れがない温度においては発電に適した効率の良い流路断面を持つ流路（小流路）を使って発電することができる。
また大流路と前記小流路へのガスの流量を制御する第１制御弁を備えたので、燃料電池が暖機された後、大流路から直接排出されるガスを遮断あるいは減少させて小流路のガス利用率を高めることができる。また昇温中においても大流路に直接導入かつ排出されるガス量の制御により大流路と小流路のガス分配を適正化することができる。
また、燃料電池の温度に応じて第１制御弁を制御し、氷点下からの燃料電池システムの起動時に、氷点下状態でもガスの流通可能な断面積を有する大流路にガスを流通させて大流路域で発電を生じさせ、発電に伴う熱により燃料電池を解凍および昇温し、燃料電池が所定温度以上の通常運転時に小流路にガスを流通させ、小流路域で発電する。したがって、氷点下時においては大流路域での発電が可能であり、この発電時に生じる熱により小流路等燃料電池内を解凍および昇温でき、燃料電池が所定温度となったときに小流路での発電が可能と判断してガスを小流路に流通させて、小流路域での発電を開始し、解凍と昇温を促進し、燃料電池の起動性を向上できる。この燃料電池を車両に搭載することで、外部からの加温手段を用いることなく、継続的に安定して運転することが可能となる。
【００３５】
第３の発明では、小流路は、大流路からガスが導入されるように連通されるとともに第２排出口を備え、第１制御弁は、大流路の第１排出口下流に設けられるので、小流路が閉塞している場合には第１制御弁を開き、大流路のみで発電し発電による熱で小流路内を解氷することができる。
【００３６】
第４の発明では、小流路は、第２導入口を備えるとともに大流路に前記ガスを導入するように連通し、第１制御弁は、大流路の第１導入口上流に設けられるので、小流路が閉塞している場合には第１制御弁を開き、大流路のみで発電し発電による熱で小流路内を解氷することができる。
【００３７】
第５の発明では、流路は、流路断面積の大きな大流路と、この大流路の流路途中で連通し、大流路の流路断面積より小さい流路断面積で形成される小流路とからなるとともに、流路は、複数の大流路とこれら大流路間を連通する小流路とから構成され、少なくとも大流路の１つは、ガスが流入する第３導入口とガスが排出される第３排出口とを備え、他の大流路は、ガスが排出される第４排出口を備え、第３導入口と第３排出口とを備えた大流路の下流にガスの流量を制御する第１制御弁を設けたので、第３導入口と第３排出口を備えた大流路で生じた熱を逃すことなく、より効率よく小流路の加熱に利用することができる。
また、燃料電池の温度に応じて第１制御弁を制御し、氷点下からの燃料電池システムの起動時に、氷点下状態でもガスの流通可能な断面積を有する大流路にガスを流通させて大流路域で発電を生じさせ、発電に伴う熱により燃料電池を解凍および昇温し、燃料電池が所定温度以上の通常運転時に小流路にガスを流通させ、小流路域で発電する。したがって、氷点下時においては大流路域での発電が可能であり、この発電時に生じる熱により小流路等燃料電池内を解凍および昇温でき、燃料電池が所定温度となったときに小流路での発電が可能と判断してガスを小流路に流通させて、小流路域での発電を開始し、解凍と昇温を促進し、燃料電池の起動性を向上できる。この燃料電池を車両に搭載することで、外部からの加温手段を用いることなく、継続的に安定して運転することが可能となる。
【００４２】
第６の発明は、大流路を電極面の内部に配置し、その両側に小流路を形成したので、大流路の発生する熱を外部に逃すことなく小流路を昇温することができる。
【００４３】
第７の発明は、小流路のガス流量を制御する第２制御弁を備えたので、低温起動時に小流路のガス流通を遮断して、ガス流通により生じる生成水が凍結して小流路が閉塞するのを防ぐことができる。
【００４４】
第８の発明は、固体高分子電解質膜に対峙する２つの電極のそれぞれの電極側でガス流れ方向が逆向きであるので、ガスの流れをいわゆる、対向流とすることができる。したがって、ガスの加湿量が抑制された、または外部からの加湿が供給されない状態でも燃料電池が安定して運転される。
【００４５】
第９の発明は、小流路のガス流れ方向に対して上流部と下流部に前記大流路を形成し、小流路の上流部と下流部で大流路と連通するようにしたので、ガスの流通方向を容易に切換選択できる。
【００４６】
第１０の発明は、第１制御弁を開放し、大流路に直接ガスを導入かつ排出する経路を構成するとともに、小流路へのガス流入を遮蔽し、大流路にガスを供給することで、大流路域での発電を開始し、流路の閉塞を起こすことなく燃料電池に発熱させることができる。続いて燃料電池の温度を検出し、検出温度と燃料電池の発電と温度との特性に基づいて設定された設定温度を比較し、検出温度が設定温度以上のときにガスを小流路に供給するように第１、第２制御弁を制御するので、燃料電池が設定温度以上であることで、小流路内をガスが流通可能であると判断し、確実に小流路域での発電を開始することができる。
【００４７】
第１１の発明は、燃料電池の検出温度が設定温度以上のときに固体高分子電解質膜に対峙する２つの電極のそれぞれの電極側でガス流れ方向を逆向きとしてガスを小流路に供給するように制御するので、流路の閉塞を伴うことなくガスを導入し、ガスの加湿量が抑制された、または外部からの加湿が供給されない状態でも発電を開始することができ、さらにいわゆる対向流とすることでガスの加湿量が抑制された、または外部からの加湿が供給されない状態でも燃料電池が安定して運転される。
【００４８】
第１２の発明は、燃料電池からの電力の供給を停止し、発電を止め、電力供給停止後小流路にガスを供給することで燃料電池が保持する電圧をガスの流通を行いながら低減し、安全に燃料電池を停止することができる。また小流路へのガスを流通を行うことで、発電によって生成した水を含有する電解質膜の乾燥を行うことができる。小流路へのガスの供給を停止し、大流路へ直接ガスを供給し、排出されるように第１、２制御弁を制御することで、大流路部分の電解質膜の乾燥を更に進めることができ、これにより次回の起動時の流路の凍結による閉塞を防止する。
【００５０】
第１３の発明は、発電のために供給されるガスの一部は、低湿度状態で供給されるので、ガスの加湿に必要な水分量を削減でき、車載性を向上できる。
【００５１】
第１４の発明は、発電のために供給されるガスの一部は、外部で加湿されることなく供給されるので、低温起動時においてもガスを加湿する加湿水の溶融ステップを経る必要がないため、燃料電池へのガスの流通を速やかに行うことができ、燃料電池システムの起動時間を短縮できる。さらに、燃料電池システムの小型化が可能となり、車載性を向上する。また加湿用の水を搭載する必要がないため、システムの軽量化に寄与する。
【００５２】
第１５の発明は、セパレータにガスが流入してから排出されるまでを通して流路断面積の大きな大流路と、この大流路に連通する大流路の断面積より小さい断面積で形成される小流路を形成し、大流路と小流路には、それぞれの流量を制御する第１、第２制御弁が設けられる。燃料電池の温度に応じて第１、第２制御弁を制御し、氷点下からの燃料電池システムの起動時に、氷点下状態でもガスの流通可能な断面積を有する大流路にガスを流通させて大流路域で発電を生じさせ、発電に伴う熱により燃料電池を解凍および昇温し、燃料電池が所定温度以上の通常運転時に小流路にガスを流通させ、小流路域で発電する。したがって、氷点下時においては大流路域での発電が可能であり、この発電時に生じる熱により小流路等燃料電池内を解凍および昇温でき、燃料電池が所定温度となったときに小流路での発電が可能と判断してガスを小流路に流通させて、小流路域での発電を開始し、解凍と昇温を促進し、燃料電池の起動性を向上できる。この燃料電池を車両に搭載することで、外部からの加温手段を用いることなく、継続的に安定して運転することが可能となる。
【００５３】
【発明の実施の形態】
以下、本発明の燃料電池１００について、図面を参照しながら説明する。
【００５４】
図１は、本発明の燃料電池システムに用いた燃料電池１００の一実施形態の構成を示す図である。本発明の燃料電池１００は、固体高分子電解質型燃料電池を用いており、燃料電池１００を構成する積層構造体（ＭＥＡ）は、固体高分子電解質から構成される電解質膜１と、この電解質膜１を狭持するように配設され、電解質膜１との界面に触媒を担持した２つの電極、アノード極２とカソード極３とを有し、燃料電池１００は、このＭＥＡを隔壁としてのセパレータ４を介して積層上に形成して構成される。
【００５５】
電解質膜１は、プロトン伝導性を有するフッ素樹脂系の固体高分子材料からなり、２つの電極２、３は、触媒、例えば白金または白金と他の金属を担持したカーボン微粒子を塗布したカーボンペーパまたはカーボンクロスから構成される。セパレータ４は、ガス不透過性を有する緻密性カーボン材で構成され、少なくとの一面には燃料ガスや酸化性ガス、あるいは冷却媒体を流通する流路を形成するための多数のリブが形成される。アノード極２に供給された燃料ガスとカソード極３に供給された酸化剤ガスはそれぞれの流路を流通し、電気化学反応を生じて排出される。
【００５６】
図２は、燃料電池１００を用いて駆動される車両の構成を模式的に示したものである。燃料電池１００の各電極間に生じた起電力により外部負荷に電力が供給される。図２においては、タイヤ駆動用のモータ５０が外部負荷であり、モータ５０は回転力を生じてタイヤ６０を駆動する構成である。後に詳述するような低温時に起動可能な燃料電池を様々な環境に晒される車両に搭載することで、外部からの加湿手段を用いることなく、継続的に安定して運転することが可能となる。
【００５７】
図３は、第１の実施形態のカソード極３側セパレータ４の平面図であり、この図を用いて構成を説明する。なお、アノード極２側についても供給されるガスの種類が異なる点（酸化剤ガスに代わり燃料ガスが流通する）に起因する構成の違いを除いて同様の構成となる。
【００５８】
カソード極３側のセパレータ４は、前述したように平行に設けられた複数のリブによって形成された酸化剤ガスが流通する複数の小流路５と、それぞれの小流路５に連通する小流路より断面積の大きな入口側マニフォールド（大流路）６と出口側マニフォールド７を備える。入口側マニフォールド６は、酸化剤ガスを供給するガス導入口８、および酸化剤ガスが小流路５に流入することなく直接入口側マニフォールド６から排出される第１ガス排出口９とを備える。そして出口側マニフォールド７の酸化剤ガス流れ方向下流側には、小流路５を通過した酸化剤ガスが排出される第２排出口１０が設けられる。
【００５９】
燃料電池での発電を司る電解質膜１と各電極２、３は、セパレータ４の小流路５及び入口側マニフォールド６と対峙するように構成される。したがって、発電は小流路５の領域で生じるとともに、入口側マニフォールド６の領域でも生じさせることが可能である。
【００６０】
以上のように、入口側マニフォールド６と出口側マニフォールド７の断面積は、小流路５の断面積より大きく設定されており、このような構成によって、入口側マニフォールド６と出口側マニフォールド７は、断面積の小さな第１流路より凍結による閉塞が生じにくい。
【００６１】
さらに入口側マニフォールド６には小流路５の断面積より大きな断面積を持つガス導入口及び排出口が設けられているので、外気温度が氷点下で小流路５がたとえ氷によって閉塞された状態からの起動時であっても、断面積の大きな入口側マニフォールド６は凍結によって閉塞されることなく酸化剤ガスが流通可能となる。酸化剤ガスをガス導入口８から入口側マニフォールド６に供給し、第１排出口９から排出することにより、入口側マニフォールド６領域での発電が可能となり、発電に伴う熱によって、燃料電池（例えば、小流路５）の解氷を促進することが可能となる。
【００６２】
このように本発明においては、酸化剤ガスまたは燃料ガスを複数の小流路５に分配する入口側マニフォールド６を小流路５より大きな断面積として形成するとともに、入口側マニフォールド６に供給されたガスが小流路５に流入せずに排出される第１排出口９を設けたことにより、氷点下時においても入口側マニフォールド６が閉塞されずに発電可能で、発電による熱を用いて小流路５の氷を解氷して小流路５領域での発電を可能とし、速やかに燃料電池の起動を行うことができる。
【００６３】
また、入口側マニフォールド６の断面積を小流路５より大きくする手段としては、セパレータの厚みに影響を与える流路の深さ方向よりも、流路の幅を大きくすることが考えられるが、限られた容積の中で燃料電池を使用することを考えると、入口側マニフォールド６の幅を小流路５の幅よりも３０倍以上大きく設定すると小流路５の発電領域が大きく減少し、燃料電池としての発電効率が低下する。したがって、幅を大きくすることにより断面積を大きくする場合には、入口側マニフォールド６の幅は、小流路５の幅に対して１倍より大きく３０倍以下とすることが望ましい。
【００６４】
ここでは、カソード極側のセパレータを代表して説明したが、アノード側のセパレータもほぼ同様の構成で適用することができ、燃料電池として構成する際には、入口側マニフォールド同士を電解質膜１を挟んで対峙するように構成することで、より効率よく発電により生じる熱を解氷に用いることができる。
【００６５】
図４は、第１の実施形態における燃料電池システムの構成を説明する図である。カソード極３側の酸化剤ガスを供給するガス導入口８には、コンプレッサ１１からの酸化剤、例えば空気が所定流量に制御されて供給される。同様にしてアノード極２側の入口側セパレータに、燃料ガスとして水素あるいは改質ガスが供給される。
【００６６】
燃料電池の第１排出口９から排出される排酸化剤ガスと第２排出口１０から排出される排酸化剤ガスはそれぞれの流路に設置された第１、第２制御弁１３、１４によって所定流量に制御されて排出される。なお、第１、第２制御弁１３、１４は流路配管途中に設置されても、燃料電池内に一体的に設けられてもよい。
【００６７】
第１、第２制御弁１３、１４の開度は、コントローラ１５によって制御され、コントローラ１５は、温度検出器１６が検出する燃料電池内の温度に基づいて、第１、第２制御弁１３、１４の開度を制御する。つまり、氷点下状態では、生成水が凍結して小流路５が閉塞することがあるので小流路５のガス流通は避けて、第１排出口９からのみ排酸化剤ガスを排出するように第１制御弁１３を開き、入口側マニフォールド６領域でのみ発電を続ける。この発電の熱による解氷または昇温が進んで生成水が生じても凍結で小流路５が閉塞することがなくなれば、第２排出口１０から排酸化剤ガスが排出されるように第２制御弁１４を開き、さらに入口側マニフォールド６から直接ガスが排出されないように第１制御弁１３を遮蔽する。
【００６８】
図５のフローチャートを用いて、コントローラ１５が行う氷点下状態からの起動時の制御内容について説明する。ここでは酸化剤ガスを例にして説明するが、燃料ガスについても同様の制御が行われる。
【００６９】
まずステップ１で、第２制御弁１４を開き、一方で第１制御弁１３を遮蔽する（ステップ２）。ステップ３で、入口側マニフォールド６に酸化剤ガスを供給する。前述したように入口側マニフォールド６に酸化剤ガスが供給されることにより燃料電池が発電を開始し、熱を生じる。この時生成水の一部が凍結する可能性があるものの、ガスの導入部から排出部までを通して断面積が大きいため、流路を閉塞するまでには至らない。一方、図６に示すように氷点下状態での発電効率は著しく低く、６０℃から９０℃で最も高い効率を示す。したがって氷点下時の低い発電効率は、言い換えると、発電に寄与しない酸化剤ガスのエネルギが熱として放出されることになり、この熱を燃料電池の加熱に用いることで、迅速に解氷を行うことができる。
【００７０】
ステップ４では、温度検出器１６が検出した燃料電池の温度を入力する。そしてステップ５で、予め計測した燃料電池の温度特性に基づき設定された、小流路５に酸化剤ガスを流通可能な温度と、検出された温度とを比較する。
【００７１】
検出温度が設定温度より高いときには、ステップ６で第２制御弁１４を開く一方、ステップ７で第１制御弁１３を閉じる。検出温度が高いことは小流路５を酸化剤ガスが流通可能であることを示しており、小流路５に酸化剤を供給することで、発電を生じ、解氷を促進し、起動性を向上する。
【００７２】
したがって、氷点下の状態から燃料電池の起動を迅速に行うことができ、いち早く燃料電池の発電効率の高い運転を行うことができる。なお、第１制御弁１３と第２制御弁１４の切換は、オンオフ的な切換ではなく、例えば小流路５の閉塞発生と相関するガス流量値よりも少ない流量でガスを流通するよう、温度や燃料電池の出力、あるいはガスが含む湿度に応じて徐々にその開度を変化させるようにしてもよい。
【００７３】
図７に示したフローチャートは、コントローラ１５が燃料電池システム停止時に行う制御内容を説明するものである。基本的な制御は、図５に示した起動時の制御内容を逆に行うものである。図５の場合と同様に酸化剤ガスの場合を取り上げて説明するが、燃料ガスでも同様に実施することができる。
【００７４】
まずステップ１で、酸化剤ガスを供給したままで、電力の供給を停止する。次にステップ２で電力の供給停止後、所定時間の間、小流路５への酸化剤ガスの供給を継続し、燃料電池内の流路、ＭＥＡ内に存在する余分な水分を乾燥させる。ステップ３で、第１制御弁１３を開き、続くステップ４で、第２制御弁１４を閉じ、入口側マニフォールド６に酸化剤ガスが供給されるが、小流路５への酸化剤ガスの供給は停止した状態となる。そして、ステップ５で、入口側マニフォールド６内が所定の乾燥状態となったならば、酸化剤ガスの供給を停止し、燃料電池システムとしての運転を終了する。
【００７５】
このような終了方法とすることにより特に入口側マニフォールド部分の乾燥を重点的に行って、氷点下状態での長期間の燃料電池の保管であっても、燃料電池が凍結しにくく、次回起動時の水分の凍結による起動性悪化を防止することができる。
【００７６】
図８から図１４は、大流路（図３とこれまでの説明では入口側マニフォールドと称した）６と小流路５の他の位置関係とガスの流れを示す模式図である。
【００７７】
まず図８は、大流路６と小流路５のガス流れ方向を平行に配置したもので、大流路６と小流路５にはそれぞれ独立してガスが供給されるようにした構成である。図の流れ方向は同じであるが、逆向きとしても小流路５の昇温を得ることができる。この例のように大流路６と小流路５の一部を隣接させると、小流路５の全長に渡り解凍と昇温が進み、他の小流路５に先駆けてガス流通が可能となる。
【００７８】
図９は、小流路５へのガスの供給が大流路６の上流寄りから小流路５の上流側に行われるように、小流路５と大流路６が連通した構成である。このような構成では、大流路６と小流路５のガス導入部を共通化することができる。大流路６と小流路５は平行で、かつ同じ方向に流れているが、他のガスの流れ（流路形状）の組み合わせとすることもできる。
【００７９】
図１０に示す構成は、小流路５の下流側出口部が大流路６の上流部に連通した構成である。このような構成では、ガスは大流路と小流路の両流路に流れるので、ガス利用率を高めることができる。この例では大流路６、小流路５ともに折り返し部を持った１本の流路としたが、それぞれ他のガスの流れ（流路形状）としても構わない。
【００８０】
図１１は、小流路５下流側が大流路６の下流寄りと連通した構成である。この様な構成では、大流路と小流路のガス排出部を共通化することができる。大流路、小流路ともに複数の平行流を持つものとしたが、他のガスの流れ（流路形状）を組み合わせることもできる。
【００８１】
図１２に示す構成は、ガスの供給が大流路６の下流寄りから小流路５の上流側に行われるように、小流路５の上流と大流路６の下流が連通した構成である。このような構成では、大流路６で昇温したガスが小流路５に導入されるので、小流路５をガスの持つ顕熱で昇温することが可能となる。また、大流路６から小流路５に流入するガスには、大流路６で生成された水の一部が含まれるため、膜（ＭＥＡ）を湿潤化する効果もある。ここでは、大流路６内のガス流れ方向と小流路５のガス流れ方向を平行にかつ逆方向となるように配置したが、他のガスの流れ（流路形状）を組み合わせたものであっても構わない。
【００８２】
第１の実施形態のように、大流路６の発電部分において小流路５を大流路６に連通させた場合、流路レイアウト上の自由度が向上するだけでなく、図３のように大流路６を小流路５の上流に位置させることで大流路６から流出する昇温したガスを小流路５に導入すれば複数の小流路を同時に昇温し、ＭＥＡを湿潤化することができる。また、図１３のように大流路６を１つのセパレータ面上で複数形成し、燃料電池の特性から昇温が望まれる部分に大流路６を配置して、昇温の効率を高めることもできる。
【００８３】
このように本発明の構成は、小流路５と大流路６の配置やそれぞれのガスの流れ（流路形状）には影響されず、燃料電池の設計条件に応じて適宜変更することが可能である。なお、図９、図１２、あるいは前述の図３に示した小流路５の上流側に、大流路６が配置される構成にあって、外部流路配管などで流路の切り替え等を行わないのであれば、第１制御弁は大流路６から排出されるガスの流量を制御するように配置されることになる。一方、図１０、図１１に示した小流路５の下流側に、大流路６が配置される構成にあって、外部流路配管などで流路の切り替え等を行わないのであれば、第１制御弁は大流路６に供給されるガスの流量を制御するように配置されることになる。
【００８４】
例えば図８に示した構成のように大流路６に隣接するように小流路５を設置すると、大流路６での発熱を隣接する小流路５の全域の加熱のために用いることができる。小流路５の一部がガスの流通可能となることで、小流路５での発電を開始することが可能で、したがってその発電に伴う発熱により別の小流路５の解氷と昇温が促進され、連鎖的に小流路５の発電量が増大し、発熱量もまた増大する。このような場合には解氷と昇温が進むほど、小流路５に供給されるガス量を増加し、一方で、大流路６から直接排出されるガス量を減少させる。
【００８５】
このように図８から図１３に示すような流路構成でも、大流路６の断面積が小流路の断面積より大きく設定されることにより、大流路６の凍結による閉塞を防止でき、氷点下状態からの起動時においても、大流路部での発電に伴う発熱によって、燃料電池を解氷および昇温することができ、燃料電池システムの起動性を向上することができる。
【００８６】
図１４に示す第２の実施形態は、第１の実施形態に対して、電極面の内部（本例では略中央）に形成された入口側マニフォールド６（大流路）を挟んで両側に小流路に相当する流路５ａ、５ｂを形成したものである。このような構成とすることで、入口側マニフオールド６で生じた熱を逃すことなく、より効率よく流路５ａ、５ｂの加熱のために利用することができる。
【００８７】
図１５に示す第３の実施形態は、第１の実施形態の出口側マニフォールド７に酸化剤ガスを供給する第２ガス導入口１７を設け、この第２ガス導入口１７から供給された酸化剤ガスが、直接第２排出口１０から排出されるように構成したものである。このような構成とすることで、入口側マニフォールド６（上流に位置する大流路）での発熱に加えて、出口側マニフォールド７（下流に位置する大流路）での発熱によって、小流路５の氷を解氷することができ、より起動性を向上することができる。
【００８８】
図１６は、第３の実施形態の構成を説明するための図である。図４に示した第１の実施形態の構成に対して出口側マニフォールド７にもコンプレッサ１１から空気が供給されるように構成される。入口側マニフォールド６に供給される空気の流量が第３制御弁１８によって制御される。出口側マニフォールド７に供給される空気の流量が第４制御弁１９によって制御される。なお本実施形態では、コントローラ１５は、第１の実施形態の機能に加味して第３制御弁１８と第４制御弁１９の開閉を制御する。
【００８９】
図１７は、第３の実施形態のコントローラ１５が氷点下状態からの起動時に実施する制御内容を説明するためのフローチャートである。
【００９０】
まずステップ１で、入口側マニフォールド６と出口側マニフォールド７に空気を供給し、直接排出するために第１、第２制御弁１３、１４を開く。供給される空気の流量は、第３、第４制御弁１８、１９によって制御される。次にステップ２でコンプレッサ１１を運転して空気を入口側マニフォールド６と出口側マニフォールド７に空気を供給する。
【００９１】
ステップ３で、温度検出器１６によって燃料電池の温度を測定し、ステップ４で、予め計測した燃料電池の温度特性に基づき設定された、小流路５に酸化剤ガスを流通可能な温度と、検出された温度とを比較する。
【００９２】
検出温度が設定温度より高いときには、ステップ５で第１制御弁１３を閉じる。続くステップ６で第４制御弁１９を閉じる。このようにして小流路５に酸化剤ガスの流通が開始され、小流路５領域での発電が開始される。
【００９３】
各マニフォールドのガス流通を行う際、入口側マニフォールド６と下流側マニフォールド７におけるガスの供給圧力差をほとんどなくすことで、小流路５へのガス流通を抑制することができる。しかし、氷点下からの発電に伴う自己発熱による加温を行うことを考えると、発電領域は広いほうが好ましいので、あえて両マニフォールド間に圧力差を設けて小流路にガス流通を行ってもかまわない。
【００９４】
さらに、図１５に示すような構造をとることで、ＭＥＡを介して相対して配設される（入口側と出口側の）二つのマニフォールドのみにガス流通を行っている状態から、小流路ヘガス流通を切り換える際、アノード極２とカソード極３に供給するガスの流通方向を互いに反対方向に流通させる、いわゆる対向流とすることが容易となる。つまり昇温が完了して小流路のガス流通に切り換える際に、この様な構成では、入口側とするマニフォールドではガス導入用のガス導入口（制御弁）を開いたままガス排出用の排出口（制御弁）を閉じる一方、出口側とするマニフォールドではガス排出用のガス流通口を開いたままガス導入用の流通口を閉じるだけで良いので、どちらを上流とし下流とするかはどの流通口を開閉するかにより容易に選択することができる。第１の実施形態の構成においてガス流通方向を切り替えるには、例えば外部ガス配管において構成される切り換え手段を用いる等の追加の施策が必要である。カソード極とアノード極のガスを対向流とすることで、カソード極側下流で生成水が累積することで多く存在する水を、濃度差を利用して電解質膜を透過させてアノード極側の上流に供給することができるようになり、ガスの加湿量が抑制された、または外部からの加湿が全く無い状態であっても燃料電池内部の水バランスを維持して燃料電池を安定して稼動することが可能となる。また切り換えを必要とせず、対向流とするかしないかがあらかじめ一定に決まっている場合、図１６の構成から上流側となるマニフォールドの第３制御弁１８と下流側となるマニフォールドの第２制御弁１４を省略することができる。
【００９５】
本発明は、上記した実施形態に限定されるものではなく、本発明の技術的思想の範囲内でさまざまな変更がなしうることは明白である。
【図面の簡単な説明】
【図１】本発明の燃料電池の構成を示す図である。
【図２】燃料電池を用いた車両の構成を示す図である。
【図３】第１の実施形態としての酸化剤ガスが流通する流路の構成を説明する図である。
【図４】第１の実施形態の燃料電池システムの構成を示す図である。
【図５】第１の実施形態の氷点下からの起動時にコントローラが実施する制御内容を説明するフローチャートである。
【図６】燃料電池の温度と発電効率の関係を示す図である。
【図７】第１の実施形態の通常運転からの停止時にコントローラが実施する制御内容を説明するフローチャートである。
【図８】他の大流路と第１流路との構成を示す図である。
【図９】他の大流路と第１流路との構成を示す図である。
【図１０】他の大流路と第１流路との構成を示す図である。
【図１１】他の大流路と第１流路との構成を示す図である。
【図１２】他の大流路と第１流路との構成を示す図である。
【図１３】他の大流路と第１流路との構成を示す図である。
【図１４】第２の実施形態としての酸化剤ガスが流通する流路の構成を説明する図である。
【図１５】第３の実施形態としての酸化剤ガスが流通する流路の構成を説明する図である。
【図１６】第３の実施形態の燃料電池システムの構成を示す図である。
【図１７】第３の実施形態の氷点下からの起動時にコントローラが実施する制御内容を説明するフローチャートである。
【符号の説明】
１電解質膜
２アノード極
３カソード極
４セパレータ
５第１流路
６入口側マニフォールド
７出口側マニフォールド
８ガス導入口
９第１排出口
１０第２排出口
１１コンプレッサ
１３第１制御弁
１４第２制御弁
１５コントローラ
１６温度センサ
１７ガス導入口
１８第３制御弁
１９第４制御弁[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a solid polymer electrolyte fuel cell power generation system including a solid polymer electrolyte fuel cell using a solid polymer membrane as an electrolyte, and more particularly to a technology for improving startability that enables use in a cold region. Is.
[0002]
[Prior art]
  In general, a fuel cell is a device that directly converts a chemical energy of a fuel into electric energy by electrochemically reacting a fuel gas such as hydrogen as a reaction gas with an oxidant gas such as air. The fuel cells are classified into various types depending on the difference in electrolytes. As one of them, a solid polymer electrolyte fuel cell using a solid polymer electrolyte as an electrolyte is known.
[0003]
  The electrode reaction proceeding at both the fuel electrode and the oxidant electrode is as shown in the following reaction formula.
[0004]
    Fuel (anode) electrode: 2H₂→ 4H⁺+ 4e⁻          ... (1)
    Oxidant (cathode) electrode: 4H⁺+ 4e⁻+ O₂→ 2H₂O ... (2)
  When hydrogen gas is supplied to the fuel electrode, the reaction formula (1) proceeds and hydrogen ions are generated at the fuel electrode. The generated hydrogen ions permeate (diffuse) through the solid polymer electrolyte membrane in a hydrated state to reach the oxidant electrode, and oxygen-containing gas supplied to the oxidant electrode, for example, oxygen in the air, The reaction formula 2) proceeds. As the electrode reactions (1) and (2) proceed at each electrode, the fuel cell generates an electromotive force.
[0005]
  In the power generation by this fuel cell, the chemical energy of the fuel that cannot be converted into electrical energy is released as heat. Although it is necessary to cool the released heat in order to make the reaction proceed smoothly, the cooling power is small by natural cooling alone, so it is widely practiced to forcibly cool the fuel cell with circulating cooling water. (For example, JP-A-5-190193).
[0006]
[Problems to be solved by the invention]
  In solid polymer electrolyte fuel cells, the proton conductivity of the polymer electrolyte membrane relies heavily on the humidity of the reaction gas, so if the humidity of the reaction gas is too low, the polymer electrolyte membrane dries and the membrane resistance increases As a result, the fuel cell power generation characteristics are deteriorated. For this reason, in general, in order to appropriately maintain the wet state of the electrode, a method in which the reaction gas is supplied by being humidified by a humidifying means such as a humidifier has been studied. However, when the amount of water in the vicinity of the gas flow path and membrane electrode assembly increases, the condensed water penetrates into the pores of the electrode and diffusion layer, so-called “electrode wetting = flooding” occurs, and gas diffusibility decreases. This may cause deterioration of power generation characteristics.
[0007]
  Further, as shown in the above formula (2), since water is generated at the cathode electrode during power generation, flooding is more likely to occur, and control to prevent “electrode wetting = flooding” is also required.
[0008]
  For this reason, an unhumidified operation in which the solid polymer electrolyte fuel cell is operated without humidifying the reaction gas has been attempted. For example, a method of thinning a polymer electrolyte membrane or a reaction gas supplied to an anode and a cathode are mutually connected. Attempts have been made to use a so-called countercurrent flow that circulates in the opposite direction (for example, Japanese Patent Laid-Open Nos. 2001-185172 and 2001-6698).
  However, no matter how much humidification from the outside to the supplied gas is suppressed, water is generated at the cathode electrode in the above reaction as seen in the equation (2). A gas-liquid mixture will remain in the interior. When used in a cold place such as a cold region in winter, the remaining water may freeze during shutdown, so that these frozen products will interfere with gas distribution at the next start-up. Accordingly, it becomes difficult to quickly start the fuel cell system. In particular, it has been difficult to rapidly increase to an operating temperature of 60 ° C. to 90 ° C. where the power generation efficiency of the polymer electrolyte fuel cell is desirable.
[0009]
  For this reason, in starting operation of a stopped fuel cell in a cold region, many attempts have been made to warm the fuel cell to a predetermined temperature (for example, a method of heating with an electric heater (JP-A-7-29585), A method using a burner (JP-A-8-162137, etc.).
[0010]
  However, when the fuel cell is heated from the outside, the fuel cell system becomes large because it is necessary to separately provide means necessary for heating, and for example, the layout is limited to a layout mounted on a fuel cell vehicle with limited space. Will be affected.
[0011]
  For this reason, as a method of heating the fuel cell without providing an external heating device, an attempt has been made to operate the fuel cell from a low temperature and use heat generated by self-power generation (FY2000 Progress Report). P. 85 “Cold-Start Dynamics of a PEM Fuel Cell Stack.”).
[0012]
  However, when trying to generate power in a fuel cell below the freezing point, water is generated at the cathode during operation as described in Equation (2), so this generated water freezes in the gas flow path and hinders gas flow. As a result, power generation may become difficult.
[0013]
  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a fuel cell system that can be quickly started even when used in a cold region.
[0014]
[Means for Solving the Problems]
  The first invention forms a hydrogen ion permeable solid polymer electrolyte membrane, an electrode sandwiching the solid polymer electrolyte membrane, and a flow path through which the gas used for power generation flows in contact with the electrode. In the fuel cell system including the fuel cell including the separator, the flow path is a large flow path having a large cross-sectional area including a first introduction port through which gas flows and a first discharge port through which gas is discharged. And a small channel formed in the middle of the channel of the large channel and having a channel cross-sectional area smaller than the channel cross-sectional area of the large channel. A first control valve for controlling a power generation region by controlling a flow rate of the gas to the large flow path and the small flow path.The first control valve is controlled according to the temperature of the fuel cell, and when starting the fuel cell system from below freezing point, gas is circulated through the large flow path to generate power in the large flow path area. The fuel cell is thawed and heated by the accompanying heat, and when the fuel cell is above a predetermined temperature, gas is circulated through the small flow path to generate power in the small flow path area..
[0015]
  The second invention is to form a hydrogen ion permeable solid polymer electrolyte membrane, an electrode sandwiching the solid polymer electrolyte membrane, and a flow path through which the gas used for power generation is in contact with the electrode. In the fuel cell system including the fuel cell including the separator, the flow path is a large flow path having a large cross-sectional area including a first introduction port through which gas flows and a first discharge port through which gas is discharged. And a small channel formed in the middle of the channel of the large channel and having a channel cross-sectional area smaller than the channel cross-sectional area of the large channel. A first control valve for controlling the power generation region by controlling the flow rate of each gas to the large flow path and the small flow pathThe first control valve is controlled according to the temperature of the fuel cell, and when starting the fuel cell system from below freezing point, gas is circulated through the large flow path to generate power in the large flow path area. The fuel cell is thawed and heated by the accompanying heat, and when the fuel cell is above a predetermined temperature, gas is circulated through the small flow path to generate power in the small flow path area..
[0016]
  The third invention is1st or 2nd inventionInThe small flow path is communicated so that the gas is introduced from the large flow path and includes the second discharge port, and the first control valve is provided downstream of the first discharge port of the large flow path. Be.
[0017]
  The fourth invention is:1st or 2nd inventionInThe small channel includes the second inlet and communicates with the large channel to introduce the gas, and the first control valve is provided upstream of the first inlet of the large channel..
[0018]
  According to a fifth aspect of the present invention, there is formed a hydrogen ion permeable solid polymer electrolyte membrane, an electrode sandwiching the solid polymer electrolyte membrane, and a flow path through which the gas used for power generation is in contact with the electrode. In the fuel cell system including the fuel cell including the separator, the flow path communicates with a large flow path having a large cross-sectional area in the middle of the large flow path. A small channel formed with a channel cross-sectional area smaller than the cross-sectional area, and the channel is composed of a plurality of the large channels and the small channel communicating between the large channels, at least One of the large flow paths includes a third introduction port through which gas flows and a third discharge port through which gas is discharged, and the other large flow path includes a fourth discharge port through which the gas is discharged. The flow rate of the gas is controlled downstream of the large flow path having the third introduction port and the third discharge port. A first control valve forThe first control valve is controlled according to the temperature of the fuel cell, and when starting the fuel cell system from below freezing point, gas is circulated through the large flow path to generate power in the large flow path area. The fuel cell is thawed and heated by the accompanying heat, and when the fuel cell is above a predetermined temperature, gas is circulated through the small flow path to generate power in the small flow path area..
[0023]
  The sixth invention is the invention according to any one of the first to fifth inventions.The large channel is disposed inside the electrode surface, and the small channel is formed on both sides thereof.
[0024]
  The seventh invention is the invention according to any one of the first to sixth inventions.And a second control valve for controlling the gas flow rate of the small flow path.
[0025]
  The eighth invention is the invention according to any one of the first to seventh inventions.The gas flow direction is opposite on the respective electrode sides of the two electrodes facing the solid polymer electrolyte membrane.
[0026]
  According to a ninth invention, in any one of the first to eighth inventionsThe large flow path is formed at the upstream and downstream portions with respect to the gas flow direction of the small flow path, and communicates with the large flow path at the upstream and downstream portions of the small flow path.
[0027]
  The tenth invention is the seventh invention,And a controller for controlling the first and second control valves, the controller opening the first control valve, and forming a path for directly introducing and discharging gas into the large flow path; A step of closing the control valve to shield the gas flow in the small flow path, supplying a gas to the large flow path, detecting the temperature of the fuel cell, and the detected temperature and the power generation and temperature of the fuel cell. A program comprising a step of comparing set temperatures set based on characteristics and a step of controlling the first and second control valves so as to supply gas to the small flow path when the detected temperature is equal to or higher than the set temperature. It is memorized.
[0028]
  The eleventh invention is the seventh invention,And a controller for controlling the first and second control valves, the controller opening the first control valve, and forming a path for directly introducing and discharging gas into the large flow path; A step of closing the control valve to shield the gas flow in the small flow path, supplying a gas to the large flow path, detecting the temperature of the fuel cell, and the detected temperature and the power generation and temperature of the fuel cell. The step of comparing the set temperature set based on the characteristics, and the gas flow direction in the opposite direction on each electrode side of the two electrodes facing the solid polymer electrolyte membrane when the detected temperature is equal to or higher than the set temperature A program comprising a step of supplying to a small flow path is stored.
[0029]
  The twelfth invention is the invention according to any one of the seventh to eleventh inventions.The controller stops supplying power from the fuel cell, supplying gas to the small flow path after stopping power supply, and stopping supplying gas to the small flow path to the large flow path. A program comprising a step of directly supplying gas and controlling the first and second control valves so as to be discharged and a step of stopping the gas to the large flow path are stored.
[0031]
  The thirteenth invention is the invention according to any one of the first to twelfth inventions.A part of the gas supplied for power generation is supplied in a low humidity state.
[0032]
  The fourteenth invention is the invention according to any one of the first to thirteenth inventions.A part of the gas supplied for power generation is supplied without being humidified outside.
[0033]
  15th inventionComprises a solid polymer electrolyte membrane that is permeable to hydrogen ions, an electrode that sandwiches the solid polymer electrolyte membrane, and a separator that forms a flow path through which the gas used for power generation is in contact with the electrode. In the fuel cell vehicle including the fuel cell, the flow path through which the gas formed in the separator circulates is a large flow path having a large cross-sectional area from when the gas flows into until it is discharged. The first and second control valves for controlling the flow rate of each of the large flow path and the small flow path include a small flow path formed with a cross-sectional area smaller than the cross-sectional area of the large flow path communicating with the large flow path. The first and second control valves are controlled according to the temperature of the fuel cell, and when starting the fuel cell system from below freezing point, gas is circulated through the large flow path to generate power in the large flow path area. The fuel cell is defrosted and heated by the heat generated by the power generation, and the fuel Pond was the circulating gas to small flow path when the predetermined temperature or higher, to generate power with small channels zone.
[0034]
【The invention's effect】
  In the first or second aspect of the invention, since the separator has a channel (large channel) having a large channel cross-sectional area from when the gas flows in to when it is exhausted, the separator has a low water content that freezes. Even at temperatures, blockage of the channel can be avoided by the large channel. Therefore, power generation by the large flow path can be continued even in a low temperature environment, and the temperature rise of the fuel cell by self-heating can be reliably obtained. On the other hand, at a temperature at which there is no risk of freezing, power can be generated using a channel (small channel) having an efficient channel cross section suitable for power generation.
  In addition, since the first control valve for controlling the flow rate of gas to the large flow path and the small flow path is provided, the gas discharged directly from the large flow path is shut off or reduced after the fuel cell is warmed up. The gas utilization rate of the small channel can be increased. Further, even during the temperature rise, the gas distribution between the large channel and the small channel can be optimized by controlling the amount of gas directly introduced into and discharged from the large channel.
  In addition, the first control valve is controlled according to the temperature of the fuel cell, and when the fuel cell system is started from below freezing point, the gas is circulated through a large flow path having a cross-sectional area through which the gas can flow even under the freezing point state. Electricity is generated in the road area, the fuel cell is defrosted and heated by the heat accompanying the power generation, and the fuel cell is circulated through the small channel during normal operation at a predetermined temperature or higher to generate power in the small channel area. Therefore, when the temperature is below freezing, power can be generated in the large flow path area, and the heat generated during this power generation can defrost and raise the temperature in the fuel cell such as the small flow path. It is determined that power generation on the road is possible, gas is circulated through the small flow path, power generation in the small flow path area is started, thawing and temperature increase are promoted, and the startability of the fuel cell can be improved. By mounting this fuel cell on the vehicle, it becomes possible to continuously and stably operate without using external heating means.
[0035]
  In the third invention, the small flow path is communicated so that gas is introduced from the large flow path and includes a second discharge port, and the first control valve is provided downstream of the first discharge port of the large flow path. Therefore, when the small flow path is closed, the first control valve can be opened, and power can be generated only by the large flow path, and the inside of the small flow path can be defrosted by the heat generated by the power generation.
[0036]
  In the fourth invention, the small flow path includes the second introduction port and communicates so as to introduce the gas into the large flow path, and the first control valve is provided upstream of the first introduction port of the large flow path. Therefore, when the small flow path is closed, the first control valve is opened, power can be generated only by the large flow path, and the inside of the small flow path can be defrosted by the heat generated by the power generation.
[0037]
  In the fifth invention, the channel is formed with a large channel having a large channel cross-sectional area and a channel cross-sectional area communicating with the channel in the middle of the large channel and smaller than the channel cross-sectional area of the large channel. The small flow channel is composed of a plurality of large flow channels and small flow channels communicating between the large flow channels, and at least one of the large flow channels is a third through which gas flows. An inlet and a third outlet through which gas is discharged, and the other large flow path has a fourth outlet through which gas is discharged, and a large stream having a third inlet and a third outlet. Since the first control valve for controlling the gas flow rate is provided downstream of the path, the heat generated in the large flow path having the third introduction port and the third discharge port is not lost, and the small flow path is more efficiently It can be used for heating.
  In addition, the first control valve is controlled according to the temperature of the fuel cell, and when the fuel cell system is started from below freezing point, the gas is circulated through a large flow path having a cross-sectional area through which the gas can flow even under the freezing point state. Electricity is generated in the road area, the fuel cell is defrosted and heated by the heat accompanying the power generation, and the fuel cell is circulated through the small channel during normal operation at a predetermined temperature or higher to generate power in the small channel area. Therefore, when the temperature is below freezing, power can be generated in the large flow path area, and the heat generated during this power generation can defrost and raise the temperature in the fuel cell such as the small flow path. It is determined that power generation on the road is possible, gas is circulated through the small flow path, power generation in the small flow path area is started, thawing and temperature increase are promoted, and the startability of the fuel cell can be improved. By mounting this fuel cell on the vehicle, it becomes possible to continuously and stably operate without using external heating means.
[0042]
  6th inventionSince the large flow path is disposed inside the electrode surface and the small flow paths are formed on both sides thereof, the temperature of the small flow path can be raised without releasing the heat generated by the large flow path to the outside.
[0043]
  7th inventionIs provided with a second control valve for controlling the gas flow rate in the small flow path, so that the gas flow in the small flow path is interrupted at low temperature startup, and the generated water generated by the gas flow is frozen and the small flow path is closed. Can be prevented.
[0044]
  Eighth inventionSince the gas flow direction is opposite to each of the two electrodes facing the solid polymer electrolyte membrane, the gas flow can be a so-called counterflow. Therefore, the fuel cell is stably operated even when the humidification amount of the gas is suppressed or the external humidification is not supplied.
[0045]
  Ninth inventionSince the large flow channel is formed in the upstream and downstream portions with respect to the gas flow direction of the small flow channel and communicates with the large flow channel in the upstream and downstream portions of the small flow channel. The direction can be easily switched.
[0046]
  10th inventionOpens the first control valve, configures a path for directly introducing and discharging gas into the large flow path, shields gas inflow into the small flow path, and supplies gas to the large flow path. It is possible to start power generation in the flow path region and cause the fuel cell to generate heat without causing the flow path to be blocked. Subsequently, the temperature of the fuel cell is detected, the set temperature set based on the characteristics of the detected temperature and the power generation and temperature of the fuel cell is compared, and gas is supplied to the small flow path when the detected temperature is equal to or higher than the set temperature. Since the first and second control valves are controlled so that the fuel cell is at a set temperature or higher, it is determined that gas can flow through the small flow path, and power generation in the small flow path area is ensured. Can start.
[0047]
  Eleventh inventionControls the gas flow direction to be reversed and supplied to the small flow path on the respective electrode sides of the two electrodes facing the solid polymer electrolyte membrane when the detected temperature of the fuel cell is equal to or higher than the set temperature. Therefore, gas can be introduced without blocking the flow path, and power generation can be started even when the amount of humidification of the gas is suppressed or no external humidification is supplied. The fuel cell can be stably operated even when the humidification amount of the gas is suppressed or no external humidification is supplied.
[0048]
  12th inventionStops the power supply from the fuel cell, stops the power generation, and supplies the gas to the small flow path after stopping the power supply, thereby reducing the voltage held by the fuel cell while circulating the gas, and safely The battery can be stopped. Further, by circulating the gas to the small flow path, the electrolyte membrane containing water generated by power generation can be dried. The supply of gas to the small channel is stopped, the gas is directly supplied to the large channel, and the first and second control valves are controlled so as to be discharged, thereby further drying the electrolyte membrane in the large channel part. This can prevent the blockage due to the freezing of the flow path at the next start-up.
[0050]
  13th inventionSince a part of the gas supplied for power generation is supplied in a low humidity state, the amount of moisture necessary for humidifying the gas can be reduced, and the on-vehicle performance can be improved.
[0051]
  14th inventionSince part of the gas supplied for power generation is supplied without being humidified externally, it is not necessary to go through a step of melting humidified water to humidify the gas even at low temperature startup. The gas can be circulated promptly and the startup time of the fuel cell system can be shortened. Furthermore, the fuel cell system can be miniaturized, and the in-vehicle performance is improved. In addition, it is not necessary to install water for humidification, which contributes to weight reduction of the system.
[0052]
  15th inventionIs a large channel having a large channel cross-sectional area from when gas flows into the separator until it is discharged, and a small channel having a smaller cross-sectional area than that of the large channel communicating with the large channel The first and second control valves for controlling the respective flow rates are provided in the large channel and the small channel. The first and second control valves are controlled in accordance with the temperature of the fuel cell, and when starting the fuel cell system from below freezing, gas is circulated through a large flow path having a cross-sectional area through which gas can flow even under sub-freezing conditions. Electricity is generated in the flow channel region, the fuel cell is defrosted and heated by the heat generated by the power generation, and the gas is circulated through the small flow channel during normal operation of the fuel cell at a predetermined temperature or higher to generate power in the small flow channel region. Therefore, when the temperature is below freezing, power can be generated in the large flow path area, and the heat generated during this power generation can defrost and raise the temperature in the fuel cell such as the small flow path. It is determined that power generation on the road is possible, gas is circulated through the small flow path, power generation in the small flow path area is started, thawing and temperature increase are promoted, and the startability of the fuel cell can be improved. By mounting this fuel cell on the vehicle, it becomes possible to continuously and stably operate without using external heating means.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the fuel cell 100 of the present invention will be described with reference to the drawings.
[0054]
  FIG. 1 is a diagram showing a configuration of an embodiment of a fuel cell 100 used in the fuel cell system of the present invention. The fuel cell 100 of the present invention uses a solid polymer electrolyte fuel cell, and a laminated structure (MEA) constituting the fuel cell 100 includes an electrolyte membrane 1 composed of a solid polymer electrolyte, and the electrolyte membrane. 1 has two electrodes carrying an catalyst at the interface with the electrolyte membrane 1, an anode 2 and a cathode 3, and the fuel cell 100 is a separator using the MEA as a partition wall. 4 is formed on the stack via 4.
[0055]
  The electrolyte membrane 1 is made of a fluororesin-based solid polymer material having proton conductivity, and the two electrodes 2 and 3 are made of a catalyst, for example, carbon paper coated with platinum or carbon fine particles carrying platinum and other metals. Consists of carbon cloth. The separator 4 is made of a dense carbon material having gas impermeability, and at least one surface is formed with a large number of ribs for forming a flow path for flowing a fuel gas, an oxidizing gas, or a cooling medium. The The fuel gas supplied to the anode electrode 2 and the oxidant gas supplied to the cathode electrode 3 flow through the respective flow paths, and are discharged after causing an electrochemical reaction.
[0056]
  FIG. 2 schematically shows the configuration of a vehicle driven using the fuel cell 100. Electric power is supplied to the external load by the electromotive force generated between the electrodes of the fuel cell 100. In FIG. 2, the tire driving motor 50 is an external load, and the motor 50 is configured to drive the tire 60 by generating a rotational force. By mounting a fuel cell that can be activated at a low temperature, which will be described in detail later, on a vehicle exposed to various environments, it becomes possible to continuously and stably operate without using an external humidifying means. .
[0057]
  FIG. 3 is a plan view of the cathode electrode 3 side separator 4 of the first embodiment, and the configuration will be described with reference to this drawing. The anode electrode 2 also has the same configuration except for the difference in configuration caused by the difference in the type of gas supplied (fuel gas flows instead of the oxidant gas).
[0058]
  As described above, the separator 4 on the cathode electrode 3 side includes a plurality of small flow paths 5 through which an oxidant gas formed by a plurality of ribs provided in parallel flows, and a small flow communicating with each small flow path 5. An inlet side manifold (large flow path) 6 and an outlet side manifold 7 having a larger cross-sectional area than the road are provided. The inlet side manifold 6 includes a gas introduction port 8 for supplying an oxidant gas, and a first gas discharge port 9 through which the oxidant gas is directly discharged from the inlet side manifold 6 without flowing into the small flow path 5. A second discharge port 10 through which the oxidant gas that has passed through the small flow path 5 is discharged is provided downstream of the outlet side manifold 7 in the oxidant gas flow direction.
[0059]
  The electrolyte membrane 1 that controls power generation in the fuel cell and the electrodes 2 and 3 are configured to face the small flow path 5 and the inlet side manifold 6 of the separator 4. Therefore, power generation can occur in the region of the small flow path 5 and also in the region of the inlet side manifold 6.
[0060]
    As described above, the cross-sectional areas of the inlet-side manifold 6 and the outlet-side manifold 7 are set to be larger than the cross-sectional area of the small flow path 5. With such a configuration, the inlet-side manifold 6 and the outlet-side manifold 7 are Blockage due to freezing is less likely to occur than in the first flow path having a small cross-sectional area.
[0061]
  Furthermore, since the inlet side manifold 6 is provided with a gas inlet and outlet having a cross-sectional area larger than that of the small flow path 5, the small flow path 5 is blocked by ice even when the outside air temperature is below freezing point. Even at the time of start-up, the inlet side manifold 6 having a large cross-sectional area can flow the oxidant gas without being blocked by freezing. By supplying the oxidant gas from the gas inlet 8 to the inlet manifold 6 and discharging from the first outlet 9, it becomes possible to generate electric power in the inlet manifold 6 region, and the fuel cell (for example, It is possible to promote the defrosting of the small flow path 5).
[0062]
  As described above, in the present invention, the inlet side manifold 6 that distributes the oxidant gas or the fuel gas to the plurality of small flow paths 5 is formed as a cross-sectional area larger than the small flow path 5 and supplied to the inlet side manifold 6. By providing the first discharge port 9 through which the gas is discharged without flowing into the small flow path 5, the inlet side manifold 6 can be generated without being blocked even when the temperature is below freezing, and the small flow is generated using the heat generated by the power generation. The ice in the path 5 is thawed to enable power generation in the small flow path 5 region, and the fuel cell can be started up quickly.
[0063]
  Further, as a means for making the cross-sectional area of the inlet side manifold 6 larger than the small flow path 5, it is conceivable to increase the width of the flow path rather than the depth direction of the flow path that affects the thickness of the separator. Considering the use of a fuel cell in a limited volume, if the width of the inlet manifold 6 is set to be 30 times larger than the width of the small flow path 5, the power generation area of the small flow path 5 is greatly reduced. The power generation efficiency as a fuel cell decreases. Therefore, when the cross-sectional area is increased by increasing the width, it is desirable that the width of the inlet side manifold 6 be greater than 1 and less than or equal to 30 times the width of the small flow path 5.
[0064]
  Here, the cathode electrode side separator has been described as a representative, but the anode side separator can also be applied in a substantially similar configuration. When the fuel cell is configured, the inlet side manifolds are connected to the electrolyte membrane 1. By configuring so as to face each other, heat generated by power generation can be used for de-icing more efficiently.
[0065]
  FIG. 4 is a diagram illustrating the configuration of the fuel cell system according to the first embodiment. An oxidant, for example, air from the compressor 11 is supplied to the gas inlet 8 for supplying the oxidant gas on the cathode electrode 3 side at a predetermined flow rate. Similarly, hydrogen or reformed gas is supplied as a fuel gas to the inlet side separator on the anode electrode 2 side.
[0066]
  The exhaust oxidant gas discharged from the first discharge port 9 of the fuel cell and the exhaust oxidant gas discharged from the second discharge port 10 are supplied by the first and second control valves 13 and 14 installed in the respective flow paths. The discharge is controlled to a predetermined flow rate. Note that the first and second control valves 13 and 14 may be installed in the middle of the flow pipe or may be provided integrally in the fuel cell.
[0067]
  The opening degree of the first and second control valves 13 and 14 is controlled by the controller 15, and the controller 15 controls the first and second control valves 13 and 14 based on the temperature in the fuel cell detected by the temperature detector 16. The opening degree of 14 is controlled. That is, in the sub-freezing state, the generated water may freeze and the small flow path 5 may be blocked, so that the gas flow in the small flow path 5 is avoided and the exhaust oxidant gas is discharged only from the first discharge port 9. The first control valve 13 is opened and power generation is continued only in the inlet side manifold 6 region. If the small flow path 5 does not block due to freezing even when the ice is melted or the temperature rises due to the heat generated by the power generation and freezing water is generated, the exhaust gas is discharged from the second outlet 10 so that the exhaust gas is discharged. 2 The control valve 14 is opened, and the first control valve 13 is shielded so that gas is not directly discharged from the inlet side manifold 6.
[0068]
  With reference to the flowchart of FIG. 5, the contents of control performed by the controller 15 at the time of startup from the below freezing point state will be described. Here, the oxidant gas will be described as an example, but the same control is performed for the fuel gas.
[0069]
  First, in step 1, the second control valve 14 is opened, while the first control valve 13 is shielded (step 2). In step 3, an oxidant gas is supplied to the inlet side manifold 6. As described above, when the oxidant gas is supplied to the inlet side manifold 6, the fuel cell starts power generation and generates heat. At this time, although a part of the generated water may freeze, the cross-sectional area is large from the gas introduction part to the discharge part, so that the flow path is not closed. On the other hand, as shown in FIG. 6, the power generation efficiency in the sub-freezing state is extremely low, and the highest efficiency is shown at 60 ° C. to 90 ° C. Therefore, the low power generation efficiency when the temperature is below freezing, in other words, the energy of the oxidant gas that does not contribute to power generation is released as heat, and this heat can be used for heating the fuel cell to quickly defrost. Can do.
[0070]
  In step 4, the temperature of the fuel cell detected by the temperature detector 16 is input. In step 5, the temperature that is set based on the temperature characteristic of the fuel cell that is measured in advance and is capable of flowing the oxidant gas through the small flow path 5 is compared with the detected temperature.
[0071]
  When the detected temperature is higher than the set temperature, the second control valve 14 is opened in step 6, while the first control valve 13 is closed in step 7. The high detection temperature indicates that the oxidant gas can flow through the small flow path 5. By supplying the oxidant to the small flow path 5, power generation is generated, ice melting is promoted, and startability is increased. To improve.
[0072]
  Therefore, the fuel cell can be quickly started up from a temperature below the freezing point, and the fuel cell can be operated with high power generation efficiency. Note that the switching between the first control valve 13 and the second control valve 14 is not on-off switching, but is performed so that the gas flows at a flow rate smaller than a gas flow rate value correlated with the occurrence of blockage of the small flow path 5, for example. The opening degree may be gradually changed according to the output of the fuel cell or the humidity contained in the gas.
[0073]
  The flowchart shown in FIG. 7 explains the contents of control performed by the controller 15 when the fuel cell system is stopped. The basic control is to reverse the control contents at the time of startup shown in FIG. As in the case of FIG. 5, the case of an oxidant gas will be described.
[0074]
  First, in step 1, the supply of electric power is stopped while the oxidant gas is being supplied. Next, after the supply of power is stopped in step 2, the supply of the oxidant gas to the small flow path 5 is continued for a predetermined time, and the excess water present in the flow path and MEA in the fuel cell is dried. In Step 3, the first control valve 13 is opened, and in Step 4, the second control valve 14 is closed, and the oxidant gas is supplied to the inlet side manifold 6. However, the oxidant gas is supplied to the small flow path 5. Is stopped. When the inside of the inlet side manifold 6 becomes a predetermined dry state in step 5, the supply of the oxidant gas is stopped and the operation as the fuel cell system is ended.
[0075]
  By adopting such an end method, the drying of the manifold part on the inlet side is performed with particular emphasis, and even when the fuel cell is stored for a long period of time under freezing conditions, the fuel cell is difficult to freeze, Deterioration of startability due to freezing of moisture can be prevented.
[0076]
  FIGS. 8 to 14 are schematic views showing other positional relationships and gas flows of the large flow path (referred to as the inlet side manifold in FIG. 3 and the above description) 6 and the small flow path 5.
[0077]
  First, FIG. 8 shows a configuration in which the gas flow directions of the large flow path 6 and the small flow path 5 are arranged in parallel, and gas is supplied to the large flow path 6 and the small flow path 5 independently of each other. It is. Although the flow direction in the figure is the same, the temperature of the small flow path 5 can be increased even if the flow direction is reversed. When a part of the large flow path 6 and the small flow path 5 are adjacent to each other as in this example, the thawing and the temperature increase proceed over the entire length of the small flow path 5, and gas distribution is possible ahead of the other small flow paths 5. It becomes.
[0078]
  FIG. 9 shows a configuration in which the small channel 5 and the large channel 6 are communicated so that the gas is supplied to the small channel 5 from the upstream side of the large channel 6 to the upstream side of the small channel 5. . In such a configuration, the gas introducing portions of the large flow path 6 and the small flow path 5 can be shared. The large flow path 6 and the small flow path 5 are parallel and flow in the same direction, but may be a combination of other gas flows (flow path shapes).
[0079]
  The configuration shown in FIG. 10 is a configuration in which the downstream outlet portion of the small flow channel 5 communicates with the upstream portion of the large flow channel 6. In such a configuration, since the gas flows in both the large flow path and the small flow path, the gas utilization rate can be increased. In this example, each of the large flow path 6 and the small flow path 5 is a single flow path having a folded portion, but each may have a different gas flow (flow path shape).
[0080]
  FIG. 11 shows a configuration in which the downstream side of the small channel 5 communicates with the downstream side of the large channel 6. In such a configuration, the gas discharge portions of the large flow path and the small flow path can be shared. Although both the large flow path and the small flow path have a plurality of parallel flows, other gas flows (flow path shapes) can be combined.
[0081]
  The configuration shown in FIG. 12 is a configuration in which the upstream of the small channel 5 and the downstream of the large channel 6 are communicated so that the gas is supplied from the downstream side of the large channel 6 to the upstream side of the small channel 5. is there. In such a configuration, since the gas heated in the large flow path 6 is introduced into the small flow path 5, the small flow path 5 can be heated with the sensible heat of the gas. Moreover, since the gas flowing into the small flow path 5 from the large flow path 6 includes a part of the water generated in the large flow path 6, there is also an effect of wetting the membrane (MEA). Here, the gas flow direction in the large flow path 6 and the gas flow direction in the small flow path 5 are arranged in parallel and in opposite directions, but the other gas flows (flow path shapes) are combined. It does not matter.
[0082]
  When the small flow path 5 is communicated with the large flow path 6 in the power generation portion of the large flow path 6 as in the first embodiment, not only the degree of freedom in the flow path layout is improved, but also as shown in FIG. If the heated gas flowing out from the large flow path 6 is introduced into the small flow path 5 by positioning the large flow path 6 upstream of the small flow path 5, the temperature of the plurality of small flow paths is increased at the same time. Can be moistened. Further, as shown in FIG. 13, a plurality of large flow paths 6 are formed on one separator surface, and the large flow paths 6 are arranged in a portion where the temperature rise is desired from the characteristics of the fuel cell to increase the temperature rise efficiency. You can also.
[0083]
  As described above, the configuration of the present invention is not affected by the arrangement of the small flow paths 5 and the large flow paths 6 and the flow of each gas (flow path shape), and can be appropriately changed according to the design conditions of the fuel cell. Is possible. In addition, in the configuration in which the large flow path 6 is arranged on the upstream side of the small flow path 5 shown in FIG. 9, FIG. 12, or FIG. 3, the flow path is switched by an external flow path piping or the like. If not, the first control valve is arranged to control the flow rate of the gas discharged from the large flow path 6. On the other hand, if the large flow path 6 is arranged on the downstream side of the small flow path 5 shown in FIGS. 10 and 11 and the flow path is not switched by an external flow path piping or the like, The first control valve is arranged to control the flow rate of the gas supplied to the large flow path 6.
[0084]
  For example, when the small flow path 5 is installed adjacent to the large flow path 6 as in the configuration shown in FIG. 8, the heat generated in the large flow path 6 is used for heating the entire area of the adjacent small flow path 5. Can do. Since a part of the small flow path 5 can circulate the gas, it is possible to start power generation in the small flow path 5, and therefore, the heat generated by the power generation causes the deicing and rising of another small flow path 5. The temperature is promoted, the power generation amount of the small flow path 5 is increased in a chain, and the heat generation amount is also increased. In such a case, the amount of gas supplied to the small flow path 5 increases as the ice melting and the temperature increase, while the amount of gas discharged directly from the large flow path 6 is decreased.
[0085]
  As described above, even in the flow channel configuration as shown in FIGS. 8 to 13, the large flow channel 6 can be prevented from being blocked by freezing by setting the cross sectional area of the large flow channel 6 to be larger than the cross sectional area of the small flow channel. Even at the time of startup from a sub-freezing state, the fuel cell can be deiced and heated by the heat generated by the power generation in the large flow path portion, and the startability of the fuel cell system can be improved.
[0086]
  The second embodiment shown in FIG. 14 is smaller than the first embodiment on both sides with an inlet side manifold 6 (large channel) formed inside the electrode surface (substantially in the center in this example). The flow paths 5a and 5b corresponding to the flow paths are formed. By setting it as such a structure, it can utilize for the heating of the flow paths 5a and 5b more efficiently, without missing the heat which generate | occur | produced in the inlet side manifold 6. FIG.
[0087]
  The third embodiment shown in FIG. 15 is provided with a second gas introduction port 17 for supplying an oxidant gas to the outlet side manifold 7 of the first embodiment, and the oxidant supplied from the second gas introduction port 17. The gas is configured to be discharged directly from the second discharge port 10. With such a configuration, in addition to heat generation in the inlet side manifold 6 (large flow path located upstream), heat generation in the outlet side manifold 7 (large flow path located downstream) causes a small flow path. 5 ice can be thawed and the startability can be further improved.
[0088]
  FIG. 16 is a diagram for explaining the configuration of the third embodiment. In contrast to the configuration of the first embodiment shown in FIG. 4, the outlet side manifold 7 is also configured to be supplied with air from the compressor 11. The flow rate of air supplied to the inlet side manifold 6 is controlled by the third control valve 18. The flow rate of the air supplied to the outlet side manifold 7 is controlled by the fourth control valve 19. In the present embodiment, the controller 15 controls the opening and closing of the third control valve 18 and the fourth control valve 19 in consideration of the function of the first embodiment.
[0089]
  FIG. 17 is a flowchart for explaining the control contents executed when the controller 15 according to the third embodiment is activated from the below freezing point state.
[0090]
  First, in step 1, air is supplied to the inlet side manifold 6 and the outlet side manifold 7 and the first and second control valves 13 and 14 are opened for direct discharge. The flow rate of the supplied air is controlled by the third and fourth control valves 18 and 19. Next, in step 2, the compressor 11 is operated to supply air to the inlet side manifold 6 and the outlet side manifold 7.
[0091]
  In step 3, the temperature of the fuel cell is measured by the temperature detector 16, and in step 4, a temperature set based on the temperature characteristic of the fuel cell measured in advance and capable of flowing the oxidant gas through the small flow path 5; Compare the detected temperature.
[0092]
  When the detected temperature is higher than the set temperature, the first control valve 13 is closed in step 5. In the subsequent step 6, the fourth control valve 19 is closed. In this way, the flow of the oxidant gas into the small flow path 5 is started, and power generation in the small flow path 5 region is started.
[0093]
  When performing the gas flow of each manifold, the gas flow to the small flow path 5 can be suppressed by eliminating the difference in gas supply pressure between the inlet side manifold 6 and the downstream side manifold 7. However, considering heating by self-heating due to power generation from below freezing point, it is preferable that the power generation area is wide. Therefore, it is possible to intentionally create a pressure difference between both manifolds and distribute gas in a small flow path. .
[0094]
  Further, by adopting the structure as shown in FIG. 15, the gas flow is made only from two manifolds (inlet side and outlet side) that are arranged to face each other via the MEA, so that a small flow path is provided. When switching the gas flow, it becomes easy to make the flow of the gas supplied to the anode 2 and the cathode 3 flow so as to be opposite to each other, so-called counter flow. In other words, when switching to gas flow in the small flow path after the temperature rise is completed, in such a configuration, in the manifold on the inlet side, the gas exhaust port (control valve) is kept open while the gas exhaust port is open. While closing the outlet (control valve), the manifold on the outlet side only needs to close the gas inlet port while keeping the gas outlet port open, so which one is upstream or downstream It can be easily selected depending on whether the mouth is opened or closed. In order to switch the gas flow direction in the configuration of the first embodiment, an additional measure such as using a switching unit configured in an external gas pipe is required. By making the gas at the cathode and anode electrodes counter flow, water that is abundant due to the accumulation of water produced on the downstream side of the cathode,Permeate the anode sideEven if it is in a state where the amount of humidification of the gas is suppressed or there is no external humidification at allFuel cellThe fuel cell can be stably operated while maintaining the internal water balance. Further, when switching is not required and it is determined in advance whether the counter flow is constant or not, the third control valve 18 of the manifold on the upstream side and the second control valve of the manifold on the downstream side from the configuration of FIG. 14 can be omitted.
[0095]
  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea of the present invention.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a fuel cell according to the present invention.
FIG. 2 is a diagram showing a configuration of a vehicle using a fuel cell.
FIG. 3 is a diagram illustrating a configuration of a flow path through which an oxidant gas flows as a first embodiment.
FIG. 4 is a diagram showing a configuration of a fuel cell system according to the first embodiment.
FIG. 5 is a flowchart for explaining the control contents executed by the controller when starting from below the freezing point according to the first embodiment;
FIG. 6 is a graph showing the relationship between the temperature of the fuel cell and the power generation efficiency.
FIG. 7 is a flowchart for explaining the control content performed by the controller when stopping from the normal operation of the first embodiment.
FIG. 8 is a diagram showing a configuration of another large flow path and a first flow path.
FIG. 9 is a diagram showing a configuration of another large flow path and a first flow path.
FIG. 10 is a diagram showing a configuration of another large flow path and a first flow path.
FIG. 11 is a diagram showing the configuration of another large flow path and a first flow path.
FIG. 12 is a diagram showing a configuration of another large flow path and a first flow path.
FIG. 13 is a diagram showing a configuration of another large flow path and a first flow path.
FIG. 14 is a diagram illustrating a configuration of a flow path through which an oxidant gas flows as a second embodiment.
FIG. 15 is a diagram illustrating the configuration of a flow path through which an oxidant gas flows as a third embodiment.
FIG. 16 is a diagram showing a configuration of a fuel cell system according to a third embodiment.
FIG. 17 is a flowchart for explaining control contents executed by a controller when starting from below freezing point in the third embodiment;
[Explanation of symbols]
  1 Electrolyte membrane
  2 Anode pole
  3 Cathode pole
  4 Separator
  5 First flow path
  6 Inlet manifold
  7 Exit manifold
  8 Gas inlet
  9 First outlet
  10 Second outlet
  11 Compressor
  13 First control valve
  14 Second control valve
  15 Controller
  16 Temperature sensor
  17 Gas inlet
  18 Third control valve
  19 Fourth control valve

Claims

A fuel comprising a solid polymer electrolyte membrane that is permeable to hydrogen ions, an electrode that sandwiches the solid polymer electrolyte membrane, and a separator that forms a flow path through which gas used for power generation is in contact with the electrode. In a fuel cell system equipped with a battery,
The flow path communicates with a large flow path having a large cross-sectional area with a first introduction port through which gas flows in and a first discharge port through which gas is discharged, and in the middle of the flow path of the large flow path. Consisting of a small channel formed with a channel cross-sectional area smaller than the channel cross-sectional area of the channel,
The small flow path includes a second introduction port through which gas flows or a second discharge port through which gas is discharged,
Providing a first control valve for controlling the flow rate of gas to the large flow path and the small flow path and controlling the power generation region ;
The first control valve is controlled according to the temperature of the fuel cell, and when starting the fuel cell system from below freezing point, gas is circulated through the large flow path to generate power in the large flow path area, and heat generated by power generation The fuel cell system is characterized in that the fuel cell is thawed and heated by means of the above, and when the fuel cell is at a predetermined temperature or higher, gas is circulated through the small channel and power is generated in the small channel region .

A hydrogen ion permeable solid polymer electrolyte membrane;
An electrode sandwiching the solid polymer electrolyte membrane;
In a fuel cell system comprising a fuel cell consisting of a separator formed with a flow path through which gas used for power generation is in contact with this electrode,
The flow path communicates with a large flow path having a large cross-sectional area with a first introduction port through which gas flows in and a first discharge port through which gas is discharged, and in the middle of the flow path of the large flow path. Consisting of a small channel formed with a channel cross-sectional area smaller than the channel cross-sectional area of the channel,
The small flow path includes a second introduction port through which gas flows or a second discharge port through which gas is discharged,
A first control valve for controlling the flow rate of each gas to the large flow path and the small flow path and controlling the power generation region ;
The first control valve is controlled according to the temperature of the fuel cell, and when starting the fuel cell system from below freezing point, gas is circulated through the large flow path to generate power in the large flow path area, and heat generated by power generation The fuel cell system is characterized in that the fuel cell is thawed and heated by means of the above, and when the fuel cell is at a predetermined temperature or higher, gas is circulated through the small channel and power is generated in the small channel region .

The small flow path is communicated so that the gas is introduced from the large flow path and includes the second discharge port,
The fuel cell system according to claim 1 or 2, wherein the first control valve is provided downstream of the first discharge port of the large flow path.

The small channel includes the second inlet and communicates to introduce the gas into the large channel,
The fuel cell system according to claim 1 or 2, wherein the first control valve is provided upstream of the first introduction port of the large flow path.

A hydrogen ion permeable solid polymer electrolyte membrane;
An electrode sandwiching the solid polymer electrolyte membrane;
In a fuel cell system comprising a fuel cell consisting of a separator formed with a flow path through which gas used for power generation is in contact with this electrode,
The channel is a small channel formed with a large channel having a large channel cross-sectional area, and a channel having a channel cross-sectional area smaller than that of the large channel. The flow path is composed of a plurality of large flow paths and the small flow paths communicating between the large flow paths,
At least one of the large flow paths includes a third introduction port through which gas flows in and a third discharge port through which gas is discharged, and the other large flow path includes a fourth discharge port through which the gas is discharged. Prepared,
A first control valve for controlling a gas flow rate is provided downstream of the large flow path having the third introduction port and the third discharge port ;
The first control valve is controlled according to the temperature of the fuel cell, and when starting the fuel cell system from below freezing point, gas is circulated through the large flow path to generate power in the large flow path area, and heat generated by power generation The fuel cell system is characterized in that the fuel cell is thawed and heated by means of the above, and when the fuel cell is at a predetermined temperature or higher, gas is circulated through the small channel and power is generated in the small channel region .

The fuel cell system according to any one of claims 1 to 5, wherein the large flow path is disposed inside the electrode surface, and the small flow paths are formed on both sides thereof.

The fuel cell system according to claim 1, further comprising a second control valve that controls a gas flow rate of the small flow path.

The fuel cell system according to any one of claims 1 to 7, wherein a gas flow direction is opposite on each of the two electrodes facing the solid polymer electrolyte membrane.

2. The large flow path is formed in an upstream portion and a downstream portion with respect to the gas flow direction of the small flow path, and the large flow path is communicated with an upstream portion and a downstream portion of the small flow path. The fuel cell system according to any one of 8.

A controller for controlling the first and second control valves;
This controller
Opening the first control valve and configuring a path for directly introducing and discharging gas into the large flow path;
Closing the second control valve to shield gas flow in the small flow path;
Supplying gas to the large flow path;
Detecting the temperature of the fuel cell;
Comparing a set temperature set based on characteristics of the detected temperature and the power generation and temperature of the fuel cell;
8. The fuel cell according to claim 7, wherein a program comprising a step of controlling the first and second control valves so as to supply gas to the small flow path when the detected temperature is equal to or higher than a set temperature is stored. system.

A controller for controlling the first and second control valves;
This controller
Opening the first control valve and configuring a path for directly introducing and discharging gas into the large flow path; and
Closing the second control valve to shield gas flow in the small flow path;
Supplying gas to the large flow path;
Detecting the temperature of the fuel cell;
Comparing a set temperature set based on characteristics of the detected temperature and the power generation and temperature of the fuel cell;
A program comprising the steps of supplying gas to a small flow path with the gas flow direction reversed on the respective electrode sides of the two electrodes facing the solid polymer electrolyte membrane when the detected temperature is equal to or higher than the set temperature is stored. The fuel cell system according to claim 7.

The controller is
Stopping the supply of power from the fuel cell;
Supplying gas to the small flow path after stopping power supply;
Stopping the gas supply to the small flow path, supplying the gas directly to the large flow path, and controlling the first and second control valves to be discharged;
The fuel cell system according to claim 7 or 11, wherein a program comprising a step of stopping gas to the large flow path is stored.

The fuel cell system according to any one of claims 1 to 12, wherein a part of the gas supplied for power generation is supplied in a low humidity state.

The fuel cell system according to any one of claims 1 to 13, wherein a part of the gas supplied for power generation is supplied without being humidified externally.

A hydrogen ion permeable solid polymer electrolyte membrane;
An electrode sandwiching the solid polymer electrolyte membrane;
In a fuel cell vehicle equipped with a fuel cell comprising a separator formed with a flow path that circulates gas used for power generation in contact with this electrode,
The flow path through which the gas formed in the separator flows is smaller than the large flow path having a large flow path cross-sectional area from the time the gas flows in until it is discharged, and the large flow path communicating with the large flow path. It consists of a small channel formed with a cross-sectional area,
The large and small channels are provided with first and second control valves for controlling the flow rates of the respective channels, and the first and second control valves are controlled according to the temperature of the fuel cell so that the temperature is below freezing point. When the fuel cell system is started, gas is circulated through the large flow path to generate power in the large flow path area, and the fuel cell is thawed and heated by the heat generated by the power generation. A fuel cell vehicle characterized in that gas is circulated through a flow path and power is generated in a small flow path area.