JP3736374B2

JP3736374B2 - Fuel cell system

Info

Publication number: JP3736374B2
Application number: JP2001098224A
Authority: JP
Inventors: 哲生魚住
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2001-03-30
Filing date: 2001-03-30
Publication date: 2006-01-18
Anticipated expiration: 2021-03-30
Also published as: JP2002298885A

Description

【０００１】
【発明の属する技術分野】
本発明は、イオン除去フィルタが用いられた燃料電池システムの改良に関するものである。
【０００２】
【従来の技術】
燃料電池として固体高分子型の燃料電池を用いた燃料電池システムにおいては、システムの通常時の運転温度を８０℃前後に維持する必要があるため、燃料電池スタックを冷却する冷却水を循環する必要があるが、冷却水は燃料電池スタックに接触して冷却するため、冷却水は燃料電池スタックからの電流の漏れを防止する目的で導電率を低くする必要がある。
【０００３】
また燃料電池スタック内部の固体高分子膜は適度の湿潤状態でプロトン（水素イオン）伝導性を示すため、固体高分子膜は適度に水分を補給する必要がある。このため燃料電池スタックに供給される燃料ガスと酸化剤ガスは加湿器にて加湿された状態で燃料電池スタックに供給される。したがって、冷却水と同様に電流の漏れを防止するために加湿器での加湿に用いられる純水を低導電率に維持する必要がある。
【０００４】
しかしながら冷却水はその循環経路中のラジエータ（または熱交換器）、ポンプ、配管等から導電性イオンが冷却水中に溶け出し、冷却水中の導電性イオンが増加するという問題がある。
【０００５】
このことは加湿器においても同様であり、純水中に導電性イオンが溶け出し、純水中の導電性イオンが増加する。
【０００６】
したがって、燃料電池スタックから電流が漏れ、燃料電池システムの効率を低下させるという問題を生じる。
【０００７】
このような問題を解決する手段として特開平０７−４７３４９号公報に開示の技術では、図９に示すようにろ過フィルタ３３を通過した冷却水はポンプ３４によって活性炭フィルタエレメント３５ｃとイオン交換樹脂３５ｄを備えたフィルタイオン交換樹脂カートリッジ３５に供給され、イオン交換樹脂３５ｄの作用によって冷却水の導電率を低下させるようになっている。
【０００８】
【発明が解決しようとする課題】
しかしながらこの従来技術においては、冷却水または純水の全流量をイオン除去フィルタ（イオン交換樹脂３５ｄ）に通すため、燃料電池システムでは冷却水または純水の流量が２０から１００（Ｌ／ｍｉｎ）程度の流量で変化するが、イオン除去フィルタの除去能力を流量の少ない場合に適応すると大流量時にイオン除去フィルタ前後での圧力差が大きくなり、冷却水または純水を供給するポンプ負荷が増大し、燃料電池システムの効率が低下することがある。これを防ぐためには、イオン除去フィルタを薄くして、イオン除去性能を低下せざるを得ない。一方、大流量時に適応したイオン除去フィルタとすると、その形状寸法が大型化し、燃料電池システムの大型化を招き、例えば、車両等の設置スペースに制限のある場所に燃料電池を設置する際に不適切なものとなる。
【０００９】
そこで本発明の目的は、上記問題点を解決する燃料電池用イオン除去フィルタを提供することである。
【００１０】
【課題を解決するための手段】
第１の発明は、燃料電池の効率を低下させる水中の導電性イオンを除去するイオン除去フィルタを流路に備えた燃料電池システムにおいて、前記イオン除去フィルタ前後の圧力差に応じて水がイオン除去フィルタをバイパスするバイパス流路と、前記バイパス流路にイオン除去フィルタ前後の圧力差に応じて開く制御弁を設ける。
【００１２】
第２の発明は、第１に記載の発明において、水がイオン除去フィルタを通過して下流に流出する流路と、水がイオン除去フィルタを通過せずに下流に流出するバイパス流路とを一体に設け、バイパス流路にイオン除去フィルタ前後の圧力差に応じて開く制御弁を設ける。
【００１３】
第３の発明は、第１の発明において、イオン除去フィルタは下流側ほどフィルタの通過抵抗が低い構成を有し、水がイオン除去フィルタを通過して下流に流出する流路と、水がイオン除去フィルタを通過せずに下流に流出するバイパス流路とを一体に設け、バイパス流路にイオン除去フィルタ前後の圧力差に応じて流れ方向に摺動し、水のバイパス流路からイオン除去フィルタへの流れを制御する制御弁を設ける。
【００１４】
第４の発明は、第２の発明において、前記イオン除去フィルタは円筒形に構成され、その中央部の一端側開口をイオン除去フィルタ上流の流路と連通するとともに、他端側開口を閉鎖する制御弁を設け、イオン除去フィルタ前後での圧力差が所定値以下のときには制御弁が他端側開口を閉鎖して水がイオン除去フィルタを通過し、圧力差が所定値を超えると制御弁が開いて水を下流に流出するように構成される。
【００１５】
第５の発明は、第３の発明において、前記イオン除去フィルタは中心部に穴が形成された円錐形に構成され、その底面側の開口がイオン除去フィルタ上流の流路と連通するとともに、穴の途中に制御弁が設置され、イオン除去フィルタ前後の圧力差が小さいときに制御弁は上流寄りに位置して水をイオン除去フィルタ断面積の大きい領域を通過するようにし、圧力差が大きくなるほど制御弁が下流側に移動するとともに水がイオン除去フィルタを通過する領域は下流側に拡張し、圧力差が所定値を超えると制御弁がイオン除去フィルタの下流側の開口から離れて水を下流に流出するように構成される。
【００１６】
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、前記流路およびバイパス流路を通過する水の異物を除去する異物除去フィルタを備える。
【００１７】
第７の発明は、第１から５のいずれか一つの発明において、前記バイパス流路を通過する水の異物を除去する異物除去フィルタを設けると共に、イオン除去フィルタを異物除去フィルタとして機能させる。
【００１８】
【発明の効果】
第１の発明は、燃料電池システムのイオン除去フィルタ前後の圧力差に応じて水がイオン除去フィルタをバイパスするバイパス流路を設けたので、イオン除去フィルタ前後での圧力損失を抑制し、ポンプの負荷の増加を防止し、ポンプの運転効率低下を防ぎ、燃料電池システムとしての効率を維持することができる。また、前記バイパス流路にイオン除去フィルタ前後の圧力差に応じて開く制御弁を設けたので、流量が少ないときにはイオン除去フィルタに水を全量流し、流量が多くなると制御弁から水を流し流路抵抗の増大を抑制でき、ポンプの負荷の増加を防止し、ポンプの運転効率低下を防ぐことができる。
【００２０】
第２と４の発明は、水がイオン除去フィルタを通過して下流に流出する流路と、水がイオン除去フィルタを通過せずに下流に流出するバイパス流路とを一体に設け、バイパス流路にイオン除去フィルタ前後の圧力差に応じて開く制御弁を設けたので、流路の構成を簡潔にできる。
【００２１】
第３と５の発明は、イオン除去フィルタは下流側ほどフィルタの通過抵抗が低い構成を有し、水がイオン除去フィルタを通過して下流に流出する流路と、水がイオン除去フィルタを通過せずに下流に流出するバイパス流路とを一体に設け、バイパス流路にイオン除去フィルタ前後の圧力差に応じて流れ方向に摺動し、水のバイパス流路からイオン除去フィルタへの流れを制御する制御弁を設けたので、イオン除去フィルタ前後での圧損低減と伝導性イオン除去性能をバランスよく制御することができる。
【００２２】
第６の発明は、前記流路およびバイパス流路を通過するすべての水の異物を除去する異物除去フィルタを備えたので、異物除去フィルタによって冷却水中の異物が除去されて、異物によるイオン除去フィルタの目詰まりを防ぎ、寿命を延ばすことができる。
第７の発明は、前記バイパス流路を通過する水の異物を除去する異物除去フィルタを設けると共に、イオン除去フィルタを異物除去フィルタとして機能させることにより、イオン除去フィルタを通過せずに下流に流出する冷却水の異物のみを異物除去フィルタで除去し、イオン除去フィルタが異物除去フィルタを兼ねる構成として、冷却水全量の異物除去を可能とし、さらにポンプの運転負荷を低減することができる。
【００２３】
【発明の実施の形態】
図１は本発明のイオン除去フィルタを用いた燃料電池システムの構成を説明する図である。
【００２４】
本燃料電池システムは燃料と酸化剤（例えば、空気）から発電を行う燃料電池スタック１と、燃料電池スタック１に供給される燃料と空気の加湿を行う加湿器２と、燃料電池スタック１を冷却するための水を貯蔵する水タンク１１と、加湿器２に供給される純水を貯める純水タンク１４と、各構成要素間を連通する流路から構成される。
【００２５】
加湿器２には空気を供給する空気供給流路３と燃料を供給する燃料供給流路４とが接続されると共に、これら燃料と空気を加湿する純水を純水タンク１４から供給するための純水流路１２ａが接続される。加湿器２から排出される純水は排純水流路１２ｂを通って純水タンク１４に戻ることで、純水は循環する。
【００２６】
加湿器２においてそれぞれ独立して加湿された燃料と空気は、加湿空気流路５と加湿燃料流路６を通って燃料電池スタック１のアノードおよびカソードに供給される。燃料電池スタック１に供給された燃料と空気は発電後、排ガスとして空気排出流路７と燃料ガス排出流路８から外部に排出される。
【００２７】
電気化学反応に伴って加熱した燃料電池スタック１を冷却するための冷却水を水タンク１１から燃料電池スタック１に供給する冷却水流路９ａが設けられ、冷却後の冷却水が通過する排冷却水流路９ｂは水タンク１１に戻り、冷却水は循環して用いられる。
【００２８】
冷却水流路９ａの途中には、冷却水中の導電性イオンを除去する円筒形のイオン除去フィルタ１６を収装したフィルタ部１５が設置されると共に、フィルタ部１５をバイパスするバイパス流路９ｃが設けられる。ここで円筒形のイオン除去フィルタ１６はその軸方向を冷却水の流れ方向に向くように設置されており、また、バイパス流路９ｃの管路抵抗は冷却水の流量が少ないときには、イオン除去フィルタ１６とイオン除去フィルタ１６を介装した部分の冷却水流路９ａの合計の抵抗より大きくなるように設定される。たとえば、図示しないがバイパス流路９ｃにオリフィスを設けたり、断面積を冷却水流路９ａより小さくするようにしてもよい。
【００２９】
したがって、フィルタ部１５を流れる冷却水流量が少量である時には冷却水はバイパス流路９ｃを介さず、フィルタ部１５のみを通過する。このとき冷却水の全量がイオン除去フィルタ１６を通過するので、冷却水中の導電性イオンは十分に除去され、またイオン除去フィルタ１６前後での圧力差（圧損）は小さく、ポンプ負荷が増大することはない。また冷却水流量が増加し、イオン除去フィルタ１６前後での圧力差がバイパス流路９ｃの管路抵抗により生じる圧力差より高くなると、冷却水がバイパス流路９ｃを通過するので、イオン除去フィルタ１６前後での圧損を抑制することができる。したがって、ポンプの負荷の増加を防止し、ポンプの運転効率低下を抑制し、燃料電池システムとしての効率を維持することができる。
【００３０】
本実施形態においては、イオン除去フィルタ１６を冷却水流路９ａに設置したが、純水流路１２ａに設置することで、燃料電池スタック１での発電に供される燃料と空気の加湿に用いられる純水の導電性イオンを除去し、さらに冷却水流路に設置した場合と同様にシステムの効率を維持できる。
【００３１】
図２に示す第２の実施形態は、バイパス流路９ｃにイオン除去フィルタ１６の前後での圧力差に基づき開閉するリリーフ弁（制御弁）１７を設置したもので、イオン除去フィルタ１６の前後の圧力差が所定値より大きいときにリリーフ弁１７を開くように構成するものである。なお第１実施形態ではバイパス流路９ｃの管路抵抗を冷却水流路９ａより高く設定したが，この実施形態ではリリーフ弁１７がその機能を有するので、バイパス流路９ｃの管路抵抗を高く設定する必要がないことは明らかである。
【００３２】
したがって、冷却水流量が少ない、つまりイオン除去フィルタ１６の前後での圧力差が小さい時にはバイパス流路９ｃが閉じて、冷却水全量がフィルタ部１５を通過するようにしたので、冷却水中のイオン除去を確実に行うことができる一方、冷却水流量が多い時には、イオン除去フィルタ１６の前後での圧力差が所定圧を超えるとリリーフ弁１７が開き、冷却水がバイパス流路９ｃを流れることにより、イオン除去フィルタ１６の前後での圧損を小さく抑制して、ポンプの運転効率の低下を防止し、システムの効率低下を防止する。
【００３３】
図３は第３の実施形態としてフィルタ部１５とバイパス流路９ｃを一体的に構成したものを示す。フィルタ部１５内のイオン除去フィルタ１８は円筒形に構成され、その一端面１８ａをフィルタ部１５上流側の冷却水通路９ａとイオン除去フィルタ１６の内部流路１６ｂが連続するように設置し、さらに下流側の他端面１８ｃの開口部１８ｄを開閉するリリーフ弁１９を設けた。したがって冷却水はフィルタ部１５上流の冷却水流路９ａから円筒形の除去フィルタ１８の中央部に位置する中央流路１８ｂに導入されて、その流量が少量のときには除去フィルタ１８の下流側開口部１８ｄがリリーフ弁１９によって閉ざされているため、冷却水は中央流路１８ｂから外周側へ、イオン除去フィルタ１８を通過して導電性イオンを除去され下流側に流出する。
【００３４】
冷却水流量が少量時には、冷却水は全量がイオン除去フィルタ１８を通過して、導電性イオンを除去されて下流に流れるが（このときリリーフ弁１９は開口部１８ｅを閉鎖している）、冷却水流量が増量すると、内部流路１８ｂの圧力が上昇し、イオン除去フィルタ１８下流の圧力との差圧が所定圧を越えるとリリーフ弁１９が開放され、冷却水は内部流路１６ｂからリリーフ弁１９とイオン除去フィルタ１８との間（流路１８ｅ）を通過して下流側に流れ出ることで内部流路１８ｂ内の圧力が所定圧力以上に上昇することを防止し、イオン除去フィルタ前後での圧損を抑制する。第２実施形態との構成と比較して説明すると、第２実施形態のバイパス流路９ｃは、本実施形態のリリーフ弁１９がイオン除去フィルタ１８から離れた時にイオン除去フィルタ１８とリリーフ弁１９との間に形成される流路１８ｅと中央流路１８ｂに相当する。
【００３５】
このように第２実施形態のイオン除去フィルタ１６が介装された冷却水流路９ａとバイパス流路９ｃとの機能を１本の流路に一体的に構成することができ、第２実施形態の効果に加え、冷却水の流路構成を簡素にすることができる。
【００３６】
次に図４に示す第４実施形態について説明する。これは第３の実施形態に対してイオン除去フィルタの形状を変更するとともに、リリーフ弁を摺動弁（制御弁）に変更したものである。
【００３７】
本実施形態のイオン除去フィルタ２０は円錐形状を有しており、その中心は中心線上に貫通し、中央流路２０ｂを形成し、その周囲はフィルタ部２０ｃを形成する。イオン除去フィルタ２０は円錐の底面側を上流側に向けて設置され、イオン除去フィルタ２０の中央流路２０ｂの底面側開口２０ａはイオン除去フィルタ２０上流側の冷却水流路９ａと連続するように設置される。摺動弁２１はイオン除去フィルタ２０の中央流路２０ｂの途中に設けられて、摺動弁２１上流の中央流路２０ｂの圧力とイオン除去フィルタ２０下流の圧力との差圧により流れ方向に摺動する。
【００３８】
したがって冷却水流量が少量の時には図４（ａ）に示すように、摺動弁２１はイオン除去フィルタ２０の中央流路２０ｂ内の上流寄りに位置し、冷却水は中央流路２０ｂから円錐形状をしたイオン除去フィルタ２０のフィルタ層２０ｃの断面積の大きな部分を全周に渡って通過することになり、冷却水中のイオンを効率よく除去することができる。冷却水の流量が徐々に増量すると図４（ｂ）に示すように、摺動弁２１に作用する圧力が上昇し、摺動弁２１は下流側に変位する。したがって冷却水が通過するイオン除去フィルタ２０のフィルタ層２０ｃの領域が広がり、冷却水はフィルタ層２０ｃの下流側の圧力損失が小さい断面積が比較的小さな部分を通過して下流に流れ出す。冷却水流量がさらに増量すると図４（ｃ）に示すように、摺動弁２１はさらに下流側に変位し、イオン除去フィルタ２０から離れ、冷却水は中央流路２０ｂからイオン除去フィルタ２０を通過することなく、下流側に流出する。このときのイオン除去フィルタ２０とリリーフ弁２１との間の隙間（流路２０ｄ）と中央流路２０ｂが第２実施形態のバイパス流路９ｃに相当するものである。
【００３９】
したがって、冷却水流量が少量の時には圧損を考慮する必要がないので、イオン除去性能に優れたフィルタ層の断面積の大きな領域に冷却水を導き、導電性のイオンを十分に除去し、流量の増加に伴って圧損の少ないフィルタ層の薄い領域にも冷却水を導くことで圧損低減とイオン除去性能の両立をバランスよく制御することができる。さらに圧力差が大きくなったときには冷却水はバイパス流路に相当する流路２０ｂと２０ｄからイオン除去フィルタ２０を通過せずに下流に流出することになり、ポンプの運転負荷を抑制し、システムの効率向上を図ることができる。
【００４０】
次に図５に示す第５実施形態について説明する。これは第１実施形態の冷却水流路９ａとバイパス流路９ｂとの上流側分岐点の上流に冷却水中の異物を除去する異物除去フィルタ２２を設置したものである。
【００４１】
したがって異物除去フィルタ２２の効果によって冷却水中の異物が除去されて、異物による高価なイオン除去フィルタ１６の目詰まりを防ぎ、寿命を延ばすことができる。
【００４２】
なお、本実施形態では分岐点の上流に異物除去フィルタ２２を設置したが、分岐点下流の冷却水流路９ａとバイパス流路９ｃそれぞれに設置してもよい。または、イオン除去フィルタ１６を異物除去フィルタ２２としても作用させることで、バイパス流路９ｃにのみ異物除去フィルタ２２を設置するようにしてもよい。この構成では異物除去フィルタをバイパス流路にのみ設ければ良く、またイオン除去フィルタ１６に流入する冷却水への異物除去フィルタによる圧損の影響がなく、ポンプの運転負荷を低減できるという効果がある。
【００４３】
図６から図８には第２実施形態から第４実施形態の構成に異物除去フィルタを設置した構成を示しており、これらの構成ではイオン除去フィルタを通過せずに下流に流出する冷却水の異物のみを異物除去フィルタで除去し、イオン除去フィルタが異物除去フィルタを兼ねる構成としている。この構成により、冷却水全量の異物除去を可能として、さらに前述のようにポンプの運転負荷を低減することができる。
【図面の簡単な説明】
【図１】本発明の第１実施形態を説明する図である。
【図２】第２実施形態を説明する図である。
【図３】第３実施形態を説明する図である。
【図４】第４実施形態を説明する図である。
【図５】第５実施形態を説明する図である。
【図６】第６実施形態を説明する図である。
【図７】第７実施形態を説明する図である。
【図８】第８実施形態を説明する図である。
【図９】従来技術を説明する図である。
【符号の説明】
９ａ冷却水流路
９ｂ排冷却水流路
９ｃバイパス流路
１５フィルタ部
１６イオン除去フィルタ
１７リリーフ弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a fuel cell system used is ion filter.
[0002]
[Prior art]
In a fuel cell system using a polymer electrolyte fuel cell as a fuel cell, it is necessary to maintain the normal operating temperature of the system at around 80 ° C. Therefore, it is necessary to circulate cooling water for cooling the fuel cell stack However, since the cooling water contacts and cools the fuel cell stack, the cooling water needs to have a low conductivity in order to prevent leakage of current from the fuel cell stack.
[0003]
Further, since the solid polymer membrane inside the fuel cell stack exhibits proton (hydrogen ion) conductivity in a moderately wet state, the solid polymer membrane needs to be appropriately replenished with water. For this reason, the fuel gas and the oxidant gas supplied to the fuel cell stack are supplied to the fuel cell stack while being humidified by the humidifier. Therefore, it is necessary to maintain the low conductivity of the pure water used for humidification in the humidifier in order to prevent current leakage as in the case of cooling water.
[0004]
However, the cooling water has a problem that conductive ions are dissolved into the cooling water from a radiator (or heat exchanger), a pump, piping, and the like in the circulation path, and the conductive ions in the cooling water increase.
[0005]
This also applies to the humidifier, in which conductive ions are dissolved in pure water and conductive ions in pure water are increased.
[0006]
Therefore, current leaks from the fuel cell stack, causing a problem that the efficiency of the fuel cell system is lowered.
[0007]
In the technique disclosed in Japanese Patent Application Laid-Open No. 07-47349 as means for solving such problems, the cooling water that has passed through the filtration filter 33 is passed through an activated carbon filter element 35c and an ion exchange resin 35d by a pump 34 as shown in FIG. The filter ion exchange resin cartridge 35 is provided, and the conductivity of the cooling water is lowered by the action of the ion exchange resin 35d.
[0008]
[Problems to be solved by the invention]
However, in this prior art, since the entire flow rate of the cooling water or pure water is passed through the ion removal filter (ion exchange resin 35d), the flow rate of the cooling water or pure water is about 20 to 100 (L / min) in the fuel cell system. However, if the removal capacity of the ion removal filter is adapted to a small flow rate, the pressure difference before and after the ion removal filter increases at a large flow rate, and the pump load for supplying cooling water or pure water increases. The efficiency of the fuel cell system may be reduced. In order to prevent this, the ion removal filter must be thinned to reduce the ion removal performance. On the other hand, if the ion removal filter is adapted to a large flow rate, the shape and size of the filter are increased, leading to an increase in the size of the fuel cell system. For example, it is inconvenient when installing a fuel cell in a place where the installation space is limited. It will be appropriate.
[0009]
Accordingly, an object of the present invention is to provide a fuel cell ion removal filter that solves the above-mentioned problems.
[0010]
[Means for Solving the Problems]
1st invention is a fuel cell system provided with the ion removal filter which removes the conductive ion in the water which reduces the efficiency of a fuel cell in a flow path, water removes ion according to the pressure difference before and behind the said ion removal filter A bypass passage that bypasses the filter and a control valve that opens in accordance with the pressure difference before and after the ion removal filter are provided in the bypass passage .
[0012]
According to a second aspect of the present invention, in the first aspect of the present invention, a flow path in which water passes through the ion removal filter and flows downstream, and a bypass flow path in which water flows downstream without passing through the ion removal filter A control valve that is provided integrally and that opens according to the pressure difference before and after the ion removal filter is provided in the bypass channel.
[0013]
According to a third aspect , in the first aspect , the ion removal filter has a configuration in which the passage resistance of the filter is lower toward the downstream side, a flow path through which water passes through the ion removal filter and flows downstream, and water is ionized. A bypass flow path that flows downstream without passing through the removal filter is integrally provided, and the bypass flow path slides in the flow direction according to the pressure difference before and after the ion removal filter, so that the ion removal filter is removed from the water bypass flow path. A control valve is provided to control the flow to
[0014]
According to a fourth invention, in the second invention, the ion removal filter is formed in a cylindrical shape, and one end side opening at the center thereof communicates with a flow path upstream of the ion removal filter and the other end side opening is closed. A control valve is provided, and when the pressure difference before and after the ion removal filter is less than or equal to a predetermined value, the control valve closes the other end side opening, water passes through the ion removal filter, and when the pressure difference exceeds the predetermined value, the control valve It is configured to open and allow water to flow downstream.
[0015]
According to a fifth invention, in the third invention, the ion removal filter is formed in a conical shape having a hole formed in a central portion thereof, and an opening on the bottom side thereof communicates with a flow path upstream of the ion removal filter, and a hole is formed. A control valve is installed on the way, and when the pressure difference before and after the ion removal filter is small, the control valve is positioned upstream so that water passes through a region with a large cross-sectional area of the ion removal filter, and the pressure difference increases. As the control valve moves downstream, the region where water passes through the ion removal filter expands downstream, and when the pressure difference exceeds a predetermined value, the control valve moves away from the downstream opening of the ion removal filter and flows water downstream. Configured to spill.
[0016]
In a sixth aspect of the present invention, in any one of the first to fifth aspects, a foreign matter removing filter that removes foreign matter of water passing through the flow path and the bypass flow path is provided.
[0017]
According to a seventh invention, in any one of the first to fifth inventions, a foreign matter removal filter for removing foreign matter of water passing through the bypass flow path is provided, and the ion removal filter functions as a foreign matter removal filter.
[0018]
【The invention's effect】
According to the first aspect of the present invention, since the bypass channel is provided in which water bypasses the ion removal filter according to the pressure difference between the front and rear of the ion removal filter of the fuel cell system, the pressure loss before and after the ion removal filter is suppressed, It is possible to prevent an increase in load, prevent a decrease in the operation efficiency of the pump, and maintain efficiency as a fuel cell system. In addition, since the bypass flow path is provided with a control valve that opens in accordance with the pressure difference before and after the ion removal filter, when the flow rate is small, all the water flows through the ion removal filter, and when the flow rate increases, the control valve allows water to flow. An increase in resistance can be suppressed, an increase in pump load can be prevented, and a decrease in pump operation efficiency can be prevented.
[0020]
In the second and fourth aspects of the present invention, a flow path in which water passes through the ion removal filter and flows out downstream and a bypass flow path in which water flows out downstream without passing through the ion removal filter are provided integrally, Since the control valve which opens according to the pressure difference before and behind the ion removal filter is provided in the channel, the configuration of the channel can be simplified.
[0021]
In the third and fifth aspects of the invention, the ion removal filter has a configuration in which the passage resistance of the filter is lower toward the downstream side, a flow path through which water passes through the ion removal filter and flows downstream, and water passes through the ion removal filter. A bypass flow path that flows downstream without being integrated, and slides in the flow direction according to the pressure difference before and after the ion removal filter in the bypass flow path, and the flow of water from the bypass flow path to the ion removal filter Since the control valve to be controlled is provided, the pressure loss reduction before and after the ion removal filter and the conductive ion removal performance can be controlled with good balance.
[0022]
Since the sixth aspect of the present invention includes the foreign matter removal filter that removes all the foreign matter in the water that passes through the flow path and the bypass flow path, the foreign matter in the cooling water is removed by the foreign matter removal filter, and the ion removal filter by the foreign matter is removed. It can prevent clogging and extend the service life .
According to a seventh aspect of the present invention, a foreign matter removal filter that removes foreign matter of water passing through the bypass flow path is provided, and the ion removal filter functions as a foreign matter removal filter, so that it flows downstream without passing through the ion removal filter. As a configuration in which only the foreign matter of the cooling water to be removed is removed by the foreign matter removal filter and the ion removal filter also serves as the foreign matter removal filter, foreign matter removal of the entire amount of cooling water is possible, and the operating load of the pump can be reduced.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram illustrating the configuration of a fuel cell system using an ion removal filter of the present invention.
[0024]
This fuel cell system cools the fuel cell stack 1, a fuel cell stack 1 that generates power from fuel and an oxidant (for example, air), a humidifier 2 that humidifies the fuel and air supplied to the fuel cell stack 1, and the fuel cell stack 1. The water tank 11 for storing water to be used, the pure water tank 14 for storing pure water supplied to the humidifier 2, and a flow path communicating between the components.
[0025]
An air supply channel 3 for supplying air and a fuel supply channel 4 for supplying fuel are connected to the humidifier 2, and pure water for humidifying the fuel and air is supplied from a pure water tank 14. The pure water flow path 12a is connected. The deionized water discharged from the humidifier 2 returns to the deionized water tank 14 through the deionized pure water passage 12b, so that the deionized water circulates.
[0026]
The fuel and air humidified independently in the humidifier 2 are supplied to the anode and cathode of the fuel cell stack 1 through the humidified air channel 5 and the humidified fuel channel 6. The fuel and air supplied to the fuel cell stack 1 are discharged to the outside from the air discharge channel 7 and the fuel gas discharge channel 8 as exhaust gas after power generation.
[0027]
A cooling water flow path 9a for supplying cooling water for cooling the fuel cell stack 1 heated with the electrochemical reaction from the water tank 11 to the fuel cell stack 1 is provided, and the exhaust cooling water flow through which the cooling water after cooling passes is provided. The path 9b returns to the water tank 11, and the cooling water is circulated and used.
[0028]
In the middle of the cooling water channel 9a, a filter unit 15 containing a cylindrical ion removing filter 16 for removing conductive ions in the cooling water is installed, and a bypass channel 9c for bypassing the filter unit 15 is provided. It is done. Here, the cylindrical ion removal filter 16 is installed so that its axial direction is directed to the flow direction of the cooling water, and when the flow rate of the cooling water is small, the ion resistance of the bypass passage 9c is low. 16 and the ion removal filter 16 are set so as to be larger than the total resistance of the cooling water flow path 9a. For example, although not shown, an orifice may be provided in the bypass flow path 9c, or the cross-sectional area may be made smaller than that of the cooling water flow path 9a.
[0029]
Therefore, when the flow rate of the cooling water flowing through the filter unit 15 is small, the cooling water passes only through the filter unit 15 without passing through the bypass channel 9c. At this time, since the entire amount of the cooling water passes through the ion removal filter 16, the conductive ions in the cooling water are sufficiently removed, the pressure difference (pressure loss) before and after the ion removal filter 16 is small, and the pump load increases. There is no. Further, when the flow rate of the cooling water increases and the pressure difference before and after the ion removal filter 16 becomes higher than the pressure difference caused by the pipe resistance of the bypass flow path 9c, the cooling water passes through the bypass flow path 9c. Pressure loss before and after can be suppressed. Therefore, it is possible to prevent an increase in the load of the pump, suppress a decrease in the operation efficiency of the pump, and maintain the efficiency as the fuel cell system.
[0030]
In this embodiment, the ion removal filter 16 is installed in the cooling water channel 9a. However, by installing the ion removal filter 16 in the pure water channel 12a, the pure water used for humidifying the fuel and air used for power generation in the fuel cell stack 1 is used. The efficiency of the system can be maintained in the same manner as when the conductive ions in the water are removed and installed in the cooling water flow path.
[0031]
In the second embodiment shown in FIG. 2, a relief valve (control valve) 17 that opens and closes based on a pressure difference before and after the ion removal filter 16 is installed in the bypass channel 9c. The relief valve 17 is configured to open when the pressure difference is greater than a predetermined value. In the first embodiment, the pipe resistance of the bypass flow path 9c is set higher than that of the cooling water flow path 9a. However, in this embodiment, the relief valve 17 has the function, so the pipe resistance of the bypass flow path 9c is set high. Obviously there is no need to do.
[0032]
Therefore, when the flow rate of the cooling water is small, that is, when the pressure difference before and after the ion removal filter 16 is small, the bypass flow path 9c is closed so that the entire amount of the cooling water passes through the filter unit 15. On the other hand, when the flow rate of the cooling water is large, the relief valve 17 opens when the pressure difference before and after the ion removal filter 16 exceeds a predetermined pressure, and the cooling water flows through the bypass flow path 9c. The pressure loss before and after the ion removal filter 16 is suppressed to a small level to prevent the pump operation efficiency from decreasing and the system efficiency from decreasing.
[0033]
FIG. 3 shows a third embodiment in which the filter unit 15 and the bypass channel 9c are integrally configured. The ion removal filter 18 in the filter unit 15 is formed in a cylindrical shape, and its one end surface 18a is installed so that the cooling water passage 9a on the upstream side of the filter unit 15 and the internal flow path 16b of the ion removal filter 16 are continuous. A relief valve 19 for opening and closing the opening 18d of the other end face 18c on the downstream side is provided. Accordingly, the cooling water is introduced from the cooling water flow path 9a upstream of the filter section 15 into the central flow path 18b located at the center of the cylindrical removal filter 18, and when the flow rate is small, the downstream opening 18d of the removal filter 18 is provided. Is closed by the relief valve 19, the cooling water passes from the central flow path 18 b to the outer peripheral side, passes through the ion removal filter 18, removes conductive ions, and flows downstream.
[0034]
When the cooling water flow rate is small, the entire cooling water passes through the ion removal filter 18 to remove conductive ions and flows downstream (at this time, the relief valve 19 closes the opening 18e). When the water flow rate is increased, the pressure in the internal flow path 18b increases. When the pressure difference with the pressure downstream of the ion removal filter 18 exceeds a predetermined pressure, the relief valve 19 is opened, and cooling water flows from the internal flow path 16b to the relief valve. The pressure in the internal flow path 18b is prevented from rising above a predetermined pressure by passing between the flow path 19 and the ion removal filter 18 (flow path 18e) and flowing downstream, and pressure loss before and after the ion removal filter Suppress. To explain in comparison with the configuration of the second embodiment, the bypass passage 9c of the second embodiment includes an ion removal filter 18 and a relief valve 19 when the relief valve 19 of the present embodiment is separated from the ion removal filter 18. It corresponds to the flow path 18e and the central flow path 18b formed between the two.
[0035]
As described above, the functions of the cooling water flow path 9a and the bypass flow path 9c in which the ion removal filter 16 of the second embodiment is interposed can be integrally configured in one flow path. In addition to the effect, the flow path configuration of the cooling water can be simplified.
[0036]
Next, a fourth embodiment shown in FIG. 4 will be described. In this embodiment, the shape of the ion removal filter is changed with respect to the third embodiment, and the relief valve is changed to a sliding valve (control valve).
[0037]
The ion removal filter 20 of this embodiment has a conical shape, the center of which penetrates on the center line, forms the central flow path 20b, and the periphery forms the filter part 20c. The ion removal filter 20 is installed with the bottom surface side of the cone facing upstream, and the bottom surface side opening 20a of the central flow path 20b of the ion removal filter 20 is installed so as to be continuous with the cooling water flow path 9a upstream of the ion removal filter 20. Is done. The slide valve 21 is provided in the middle of the central flow path 20 b of the ion removal filter 20, and slides in the flow direction due to a differential pressure between the pressure of the central flow path 20 b upstream of the slide valve 21 and the pressure downstream of the ion removal filter 20. Move.
[0038]
Therefore, when the flow rate of the cooling water is small, as shown in FIG. 4A, the sliding valve 21 is positioned upstream of the central flow path 20b of the ion removal filter 20, and the cooling water has a conical shape from the central flow path 20b. The portion having a large cross-sectional area of the filter layer 20c of the ion removal filter 20 that has been subjected to is passed over the entire circumference, so that ions in the cooling water can be efficiently removed. When the flow rate of the cooling water is gradually increased, as shown in FIG. 4B, the pressure acting on the sliding valve 21 increases, and the sliding valve 21 is displaced downstream. Therefore, the region of the filter layer 20c of the ion removal filter 20 through which the cooling water passes is widened, and the cooling water flows downstream through a portion having a relatively small cross-sectional area with a small pressure loss on the downstream side of the filter layer 20c. When the cooling water flow rate is further increased, as shown in FIG. 4C, the sliding valve 21 is further displaced downstream, away from the ion removal filter 20, and the cooling water passes through the ion removal filter 20 from the central flow path 20b. Without going out. At this time, the gap (flow path 20d) between the ion removal filter 20 and the relief valve 21 and the central flow path 20b correspond to the bypass flow path 9c of the second embodiment.
[0039]
Therefore, there is no need to consider the pressure loss when the cooling water flow rate is small, so the cooling water is guided to a large area of the cross-sectional area of the filter layer with excellent ion removal performance, and conductive ions are sufficiently removed, With the increase, the cooling water is also guided to the thin region of the filter layer where the pressure loss is small, so that the balance between the pressure loss reduction and the ion removal performance can be controlled in a balanced manner. When the pressure difference further increases, the cooling water flows out from the flow paths 20b and 20d corresponding to the bypass flow paths downstream without passing through the ion removal filter 20, thereby suppressing the operation load of the pump and Efficiency can be improved.
[0040]
Next, a fifth embodiment shown in FIG. 5 will be described. In this embodiment, a foreign matter removal filter 22 for removing foreign matter in the cooling water is installed upstream of the upstream branch point between the cooling water passage 9a and the bypass passage 9b of the first embodiment.
[0041]
Therefore, the foreign matter in the cooling water is removed by the effect of the foreign matter removing filter 22, and the expensive ion removing filter 16 is prevented from being clogged by the foreign matter, thereby extending the life.
[0042]
In the present embodiment, the foreign substance removal filter 22 is installed upstream of the branch point, but may be installed in each of the cooling water channel 9a and the bypass channel 9c downstream of the branch point. Alternatively, the foreign substance removal filter 22 may be installed only in the bypass channel 9c by causing the ion removal filter 16 to act as the foreign substance removal filter 22. In this configuration, the foreign matter removal filter only needs to be provided in the bypass flow path, and there is no effect of pressure loss due to the foreign matter removal filter on the cooling water flowing into the ion removal filter 16, and the operation load of the pump can be reduced. .
[0043]
6 to 8 show a configuration in which a foreign matter removal filter is installed in the configurations of the second embodiment to the fourth embodiment. In these configurations, the cooling water that flows downstream without passing through the ion removal filter is shown. Only the foreign matters are removed by the foreign matter removing filter, and the ion removing filter also serves as the foreign matter removing filter. With this configuration, foreign matter can be removed from the entire amount of cooling water, and the operating load of the pump can be reduced as described above.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a second embodiment.
FIG. 3 is a diagram illustrating a third embodiment.
FIG. 4 is a diagram illustrating a fourth embodiment.
FIG. 5 is a diagram illustrating a fifth embodiment.
FIG. 6 is a diagram illustrating a sixth embodiment.
FIG. 7 is a diagram illustrating a seventh embodiment.
FIG. 8 is a diagram for explaining an eighth embodiment.
FIG. 9 is a diagram illustrating a conventional technique.
[Explanation of symbols]
9a Cooling water channel 9b Exhaust cooling water channel 9c Bypass channel 15 Filter unit 16 Ion removal filter 17 Relief valve

Claims

In a fuel cell system including an ion removal filter for removing conductive ions in water that lowers the efficiency of the fuel cell in a flow path,
A bypass flow path in which water bypasses the ion removal filter according to the pressure difference before and after the ion removal filter ;
A control valve that opens in the bypass channel according to the pressure difference before and after the ion removal filter;
A fuel cell system comprising:

A flow path through which water flows out downstream through the ion removal filter and a bypass flow path through which water flows out downstream without passing through the ion removal filter are integrally provided, and the pressure before and after the ion removal filter is provided in the bypass flow path. The fuel cell system according to claim 1 , further comprising a control valve that opens according to the difference.

The ion removal filter has a configuration in which the passage resistance of the filter is lower toward the downstream side,
A flow path through which water flows out downstream through the ion removal filter and a bypass flow path through which water flows out downstream without passing through the ion removal filter are integrally provided, and the pressure before and after the ion removal filter is provided in the bypass flow path. 2. The fuel cell system according to claim 1 , further comprising a control valve that slides in a flow direction according to the difference and controls a flow of water from the bypass channel to the ion removal filter.

The ion removal filter is configured in a cylindrical shape, and a control valve for closing one end side opening of the central portion with the flow path upstream of the ion removal filter and closing the other end side opening is provided, and pressure before and after the ion removal filter When the difference is less than the predetermined value, the control valve closes the other end side opening and the water passes through the ion removal filter, and when the pressure difference exceeds the predetermined value, the control valve opens and the water flows out downstream. The fuel cell system according to claim 2 , wherein:

The ion removal filter is configured in a conical shape with a hole formed in the center thereof, and an opening on the bottom side thereof communicates with a flow path upstream of the ion removal filter, and a control valve is installed in the middle of the hole. When the pressure difference between the front and the back is small, the control valve is positioned closer to the upstream so that the water passes through a region with a large cross-sectional area of the ion removal filter, and as the pressure difference increases, the control valve moves to the downstream side and water is ionized. The region passing through the removal filter is expanded downstream, and when the pressure difference exceeds a predetermined value, the control valve is configured to flow away from the downstream opening of the ion removal filter and to discharge water downstream. The fuel cell system according to claim 3 .

The fuel cell system according to any one of claims 1 to 5 , further comprising a foreign matter removal filter that removes foreign matter of water passing through the flow path and the bypass flow path.

The fuel cell according to any one of claims 1 to 5 , wherein a foreign matter removing filter for removing foreign matter of water passing through the bypass flow path is provided, and the ion removing filter functions as a foreign matter removing filter. system.