JP2004119083A

JP2004119083A - Fuel cell

Info

Publication number: JP2004119083A
Application number: JP2002278166A
Authority: JP
Inventors: Munehisa Horiguchi; 堀口　宗久; Hidemi Kato; 加藤　英美
Original assignee: Equos Research Co Ltd
Current assignee: Equos Research Co Ltd
Priority date: 2002-09-24
Filing date: 2002-09-24
Publication date: 2004-04-15
Anticipated expiration: 2022-09-24
Also published as: JP4470033B2

Abstract

PROBLEM TO BE SOLVED: To prevent formation of water film at the lower side of a separator by invasion of the exhaust water from the cooling space in the fuel cell separator. SOLUTION: The fuel cell comprises a separator 10B between the mutually adjoining unit cells 10A. The separator comprises an air passage S1 at least on the surface side contacting the air pole of the fuel cell and a cooling space S2 as a cooling means, on the rear side, where the air and water are supplied, and has a water drip part S2" that is sequestered from the other part of the separator at the exhaust part formed at the bottom part of the cooling space. Thereby, formation of water film due to invasion of the water from the exhaust part of the cooling space into the lower side of the separator is prevented, and closure of the exhaust part of the air passage by the water film is prevented. COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、燃料電池に関し、特にその単位セル間に介挿されるセパレータを利用した燃料電池の冷却技術に関する。
【０００２】
【従来の技術】
燃料電池の一形式としてのＰＥＭ型燃料電池の単位セルは、燃料極（一般に燃料として水素ガスが用いられることから、水素極ともいう）と酸化剤極（同様に酸化剤として酸素を含むガスである空気が用いられることから、以下これを空気極という）との間に高分子固体電解質膜が挟持された構成とされる。燃料極と空気極は、共に触媒物質を含む触媒層と、触媒層を支持するとともに反応ガスを透過される機能を有する電極基材からなる。燃料極と空気極の更に外側には、反応ガスとしての水素と空気をセル外部から電極面に均一に供給するとともに、反応ガスの余剰分をセル外部に排出するためのガス流路（一般に電極面側が開いた溝で構成される）を設けたセパレータ（コネクタ板）が積層される。このセパレータは、ガスの透過を防止するとともに、発生した電流を外部へ取り出すための集電を行う。上記のような単位セルとセパレータとで１ユニットの単電池が構成される。
【０００３】
実際の燃料電池では、かかる単電池の多数個が直列に積層されてスタックが構成される。このような、燃料電池では、十分な発電効率を維持するために、単位セル中の高分子固体電解質膜を十分に湿潤状態に保つ必要があり、一般に、電解反応により生成する水のみでは水分が不足することから、各単位セルに加湿水を供給する手段を必要とする。また、電解反応により発生電力にほぼ相当する熱量の熱が発生するため、燃料電池本体が過度にヒートアップすることを防止する冷却手段が講じられる。
【０００４】
燃料電池の冷却手段としては、従来より種々の方式のものが提案されている。それらのうちの一方式として、空気極に酸化剤としての空気を送り込むための空気マニホールド内に、水を噴射するノズルを設ける構成を採り、ガス流路に送り込む空気に水を噴射して予め混入させ、ガス流路中で水が加熱により蒸発する際の潜熱を利用して冷却するものがある。この方式のものは、本来、単位セルを湿潤状態に保つ必要があることからセルへの供給を必須とする水を、同じく空気極側への供給を必要とする空気の流れに乗せて供給し、この水を冷却にも利用するのが合理的であるとする着想に基づいている。
【０００５】
上記のような方式を採る燃料電池システムにおいて、出願人は、先の出願に係る特願２００２−５４８３９において、空気マニホールド内で水を噴射混入させた空気を、セパレータに形成した冷却空間から連通孔を経て空気流路に供給する方式のものを提案している。この方式では、冷却空間に伝わる単位セルの熱により蒸発する水の潜熱により単位セルが冷却され、蒸気化した水が空気と共に空気流路に供給される。これによりセパレータを介して単位セルを冷却しながら、空気流路への液体水又は霧状の水の侵入による流路の閉塞が防止される。すなわち、上記のような仕組みの燃料電池装置の場合、冷却空間に供給された空気と水は、燃料電池の発電時に発生する発熱を潜熱冷却するのに使われる。そして、液体の状態で供給された水の一部は冷却空間内で蒸発し、空気と一緒に水蒸気として連通孔から空気流路へ供給され、空気は燃料電池の反応に使われ、水蒸気は加湿に使われる。
【０００６】
上記のような供給方式を採る場合、冷却空間に入った空気をロスなく空気流路に供給することが重要であるとともに、同じく冷却空間に入り水蒸気にならなかった液体水を冷却空間から円滑に排出することもまた重要である。こうしたことから、出願人は、先の出願に係る特願２００２−１９６５９７において、冷却空間の最下部（通常、単位セルへの空気の供給はセル上部に開いた冷却空間の入口側から行なわれることから、空気の排出部はセル最下部となる）に溜まる液体水を排出部に常時適量滞留させることで、これを空気の冷却空間からの直抜けを阻止する閉栓として機能させる構成を提案している。
【０００７】
【発明が解決しようとする課題】
ところで、上記のように冷却空間の液体水を閉栓として機能させる構成の場合、排出部への液体水の滞留量を一定に保つことが、空気流路への水の溢れ出しを防ぎつつ閉栓機能を保つのに重要である。そのためには、排出部から順次排出されるべき水のセルからの滴下を円滑に行なわせることが重要であるが、セル最下部に位置する排出部の周囲に隣接する部材があると、この部材表面に排出水が回り込み、排出部の口部からその隣接部に膜状に広がって水の滴下（セルからの水滴の分離）を阻害する要因となる。
【０００８】
また、セルのコンパクトのためにセパレータを薄手に構成する場合、その中に画成される冷却空間や空気流路も極細の空間となるため、上記のように冷却空間の液体水を閉栓として機能させる構成に限らず、冷却空間の排出部からの排水を的確に行なうことは、隣接する空気流路からの排気を阻害しないようにする面でも重要である。
【０００９】
そこで本発明は、上記のような課題を解決すべく、セパレータにおける冷却空間の排出部からの水の滴下を促進させて、隣接部への排出水の回り込みによる排水や排気の阻害を防ぐことを目的とする。
【００１０】
【課題を解決するための手段】
前記の目的は、互いに隣接する単位セルの間にセパレータが配置される燃料電池において、前記セパレータは、単位セルの少なくとも空気極に接する表面側に設けられた空気流路と、背面側に設けられて空気と水とを供給される冷却空間とからなり、該冷却空間に伝わる単位セルの熱により蒸発する水の潜熱により単位セルを冷却する冷却手段を備え、該冷却手段の冷却空間の下部に形成された排出部に、セパレータの他の部分に対して隔絶させて水切り部が形成されたことを特徴とする構成により達成される。この構成における、前記水切り部とセパレータの他の部分との隔絶は、具体的には、水切り部の下端面とセパレータの他の部分の下端面との不連続によりなされている。より具体的には、前記水切り部とセパレータの他の部分との隔絶は、水切り部の下端面とセパレータの他の部分の下端面との面位置の上下方向のずれによりなされている。
【００１１】
前記の構成において、前記セパレータは、空気流路と冷却空間を画成する空間画成部材と、該空間画成部材に添設された枠体を備え、冷却空間の排出部に沿う枠体部分が、冷却空間の排出部の下端より上部で終端して、排出部における水切り部を枠体から隔絶している。この場合の前記水切り部は、冷却空間の排出部を構成する流路の断面積を、所定の長さに渡って狭窄させた流路狭窄部の下端で構成することができる。また、前記冷却空間は、セパレータの連通孔を介して隣接する空気流路に連通され、流路狭窄部は、該流路狭窄部に溜まる液体水により排出部を封止して空気の排出を妨げるものとすることができる。また、前記セパレータの空間画成部材は、導電性金属板材料のプレス成形品からなる一対の板状部材を板面方向に互いに当接させてなり、両板状部材の間に冷却空間を画成するものとすることもできる。
【００１２】
【作用】
前記請求項１記載の構成では、冷却空間に空気と共に供給されて蒸気化されずに、又は蒸気化後に凝縮して水滴となって排出部に達する水が、排出部に一旦液状水として滞留し、その最下部に位置する水が、隔絶された水切り部から周囲に回り込んで水膜となることなく、水滴化して落下することで順次排出される。
【００１３】
次に、請求項２に記載の構成とすると、水切り部の下端面が隣接する他の面に対する不連続により隔絶されることで、水切り部の下端面での排出水の水滴化が促進され、水切り部から滴下しやすくなる。
【００１４】
同様に、請求項３に記載の構成では、水切り部の下端面が隣接する他の面の面位置に対する上下方向のずれにより隔絶されることで、水切り部の下端面での排出水の水滴化が促進され、水切り部から滴下しやすくなる。
【００１５】
次に、請求項４に記載の構成では、冷却空間を囲う空間画成部材により画成される排出部の水切り部が、それに沿う枠体部分より下方に突出することで、枠体部分に対して隔絶されるため、水切り部を構成する面が空間画成部材の下面の極小さな面積に局限され、水切り部の下端面での排出水の水滴化が一層促進される。
【００１６】
更に、請求項５に記載の構成とすると、水切り部が冷却空間に対して絞られた流路狭窄部の下端となることで、水切り部を構成する面がより一層小さな面積に局限され、水切り部の下端面での排出水の水滴化が一層促進される。
【００１７】
また、請求項６に記載の構成とすると、冷却空間の排出部を構成する流路の狭窄部に、液体水が柱状の液滴となって滞留し、これが流路を塞ぎながら徐々に排出部から排水されることで、空気に対する連続的な封止効果が発揮され、しかも、水切り部が冷却空間に対して絞られた流路狭窄部の下端となることで、水切り部を構成する面が、空気流路の排気部に対してより一層小さな面積に局限され、水切り部の下端面での排出水の水滴化が一層促進されるため、空気流路からの排気も促進される。
【００１８】
また、請求項７に記載の構成とすると、薄肉化のためにセパレータをプレス成形品とするものにおいて、前記の各作用を生じさせることができる。
【００１９】
【発明の実施の形態】
以下、図面を参照して、本発明の実施形態を説明する。先ず、図１は、この発明の適用に係る車両用燃料電池システムの構成例を示す。このシステムは、燃料電池スタック１と、燃料電池スタック１に燃料としての水素を供給する燃料供給系（図に２点鎖線で示す）２と、同じく燃料電池スタック１に酸化ガスとしての空気を供給する空気供給系（図に１点鎖線で示す）３と、燃料電池スタック１を含むシステムの所要箇所に主として冷却のために水を供給する水供給系（図に実線で示す）４と、発電負荷としての電気負荷系（図に破線で示す）５から構成されている。
【００２０】
燃料電池スタック１は、板状の単電池を板厚方向に多数積層集合させて構成されている。図２に横断面、図３に縦断面を示すように、単電池１０は、単位セル１０Ａとセパレータ１０Ｂとで構成されている。なお、説明の都合上、図２には隣接する単位セルも併せて示し、図３では単位セルの図示は省略されている。単位セル１０Ａは、固体高分子電解質膜１１を空気極１２と燃料極１３とで挟持したものとされており、セパレータ１０Ｂは、その詳細な構造については後に詳記するが、２枚合わせの薄板金属板１４，１５の四囲を絶縁体枠１６，１７で囲った構成とされている。セパレータ１０Ｂには、燃料供給系２の水素供給路２０に連通する水素流路Ｌ１，Ｌ２と、空気供給系３の空気マニホールド３４に冷却空間Ｓ２を介して連通する空気流路Ｓ１が形成されており、燃料電池スタック１は、水素流路Ｌ１，Ｌ２を水平方向、空気流路Ｓ１を垂直方向に向けた姿勢で、空気マニホールド３４に接続された収容筐体内に配置されている。
【００２１】
燃料供給系２は、水素吸蔵合金を燃料としての水素の貯蔵部２１として構成され、該貯蔵部２１と燃料電池スタック１をつなぐ水素供給路２０の途中に、燃料電池スタック１への供給圧を調節する水素調圧弁２３と、供給遮断を制御する水素供給電磁弁２４が直列に介挿されている。燃料供給系２に関連して、燃料電池スタック１にはそれから必要に応じて水素を抜くための水素排気路２７が設けられ、その途中に、排気路開閉のための水素排気電磁弁２９と、外気の吸込みを防ぐ水素排気逆止弁２８とが介挿されている。なお、水素供給路２０には、水素調圧弁２３による調圧前後のガス圧を計測する水素１次圧センサ２２及び２次圧センサ２５が設けられている。
【００２２】
空気供給系３は、外気をフィルタ及びヒータを経て空気マニホールド３４に送り込む空気供給ファン３１を配置したダクトと、燃料電池スタック１と水素吸蔵合金の貯蔵部２１とをつなぐダクトと、貯蔵部２１と水凝縮器４６とをつなぐダクトと、水凝縮器４６からフィルタを経て使用済みの空気を外気に放出する排出路とで構成されている。この空気供給系３には、更に、燃料電池スタック１に供給される空気の温度を必要に応じたヒータ作動のために空気供給ファンの上流側で監視する吸気温度センサ３２と、燃料電池スタック１下流のダクトに付設して燃料電池スタック１から排出される空気の温度を監視する排気温度センサ３７も設けられている。
【００２３】
水供給系４は、水タンク４０を中心として、該水タンク４０から水噴射ポンプ４１により送り出される水を、空気マニホールド３４に水噴射ノズル４５により供給し、かつ、貯蔵部２１の水素吸蔵合金に吸蔵ノズル４６により供給し、燃料電池スタック１で回収及び生成された水と、水凝縮器４６での凝縮により生じた水を直接水タンク４０に戻す循環路で構成されている。循環路の供給側を構成する水噴射ポンプ４１から水噴射ノズル４５に至る水路の途中には、噴射量を調節する直噴水電磁弁４３が介挿され、水噴射ポンプ４１の吸込み側にはノズル４５の詰りを防止するためのフィルタ４２が介挿されている。水噴射ポンプ４１から吸蔵ノズル４６に至る水路の途中にも同様に噴射量を調節する吸蔵電磁弁４７が介挿されている。循環路の回収側は、燃料電池スタック１から水タンク４０に戻る水路と、水凝縮器４６からポンプ４４を経て水タンク４０に戻る水路とで構成されている。この水タンク４０には、水温センサ４７と水位センサ４８が設けられ、タンクの水温と水位の監視が可能とされている。
【００２４】
燃料電池の電気負荷系５は、燃料電池スタック１からリレー５３を経てモータ５２制御のためのインバータ５１につながる導線で構成されている。このシステムでは、燃料電池装置の空気供給ファン３１、水凝縮器４６のファン、水噴射ポンプ４１、水タンク４０の凍結対策ヒータ、各種電磁弁等の付帯設備の駆動電源として、蓄電池からなる２次電池５４が設けられており、２次電池５４は燃料電池に対して並列に接続されている。この２次電池５４は、モータ５２の回生電流を蓄積し、また、燃料電池の出力が不足している場合には、出力を補う用途にも用いられる。
【００２５】
こうした構成からなる燃料電池システムでは、水素供給電磁弁２４を閉じ、図示しない充填路からの水素ガスの供給で水素吸蔵合金への水素の吸蔵が行われる。また、水供給系４への水の供給は、給水電磁弁４８を開いて、水タンク４０へ水を供給することにより行われる。そして、発電状態では、水素供給電磁弁２４を開いて、水素調圧弁２３による調圧下で水素吸蔵合金に吸蔵させた水素を燃料電池スタック１に供給する一方、空気供給ファン３１を起動させて、空気マニホールド３４経由で燃料電池スタック１に空気を送り込む操作が行われる。この発電状態で、必要に応じて連続又は間歇的に水供給系４の水直噴ポンプ４１を運転しながら直噴水電磁弁４３を開いて水噴射ノズル４５から空気マニホールド３４内に水を噴射させることで、燃料電池スタック１への供給空気に霧状に水を混入させる操作が行われる。この水は、空気と共に燃料電池スタック１の各セパレータの冷却空間Ｓ２の上部開口から冷却空間Ｓ２に入り、蒸気化されて空気流路Ｓ１を経て各単電池の空気極１２側に供給されるものを除き冷却空間Ｓ２の排出部を構成する下部開口から筐体下部に排出され、水タンク４０に回収される。
【００２６】
上記のようにして燃料電池スタック１に送り込まれ、燃料電池スタック１で加熱された空気と水蒸気状態の水は、筐体の下部からダクトを経て水素吸蔵合金の貯蔵部２１に入り、水素吸蔵合金を加熱した後、ダクトを経て水凝縮器４６に導かれ、乾燥状態の空気と凝縮水とに分けられ、乾燥状態の空気はフィルタ経由で外気に放出され、凝縮水はポンプ４４を経て水タンク４０に戻る。また、液状のまま燃料電池スタック１を抜けた水は、直接水タンク４０に戻る。
【００２７】
このシステムの特徴は、燃料電池スタック１における空気流路Ｓ１と冷却空間Ｓ２とを一本化した流通経路に配置でき、同時に空気と水を流通させることができるので、冷却のための装置を別に設ける必要がない点にある。
【００２８】
次に、燃料電池スタック１の各単電池１０の単位セル１０Ａ間に介挿されるセパレータ１０Ｂの詳細な構成を説明する。図４に構成部材を分解して示すように、セパレータ１０Ｂは、単位セル１０Ａの空気極１２と燃料極１３（図２参照）に接触して電流を外部に取り出すための対を成す集電部材１４，１５と、それらに重ね合わされて単位セル１０Ａを支持する枠体１６，１７とを備えている。集電部材１４，１５は、この形態では、薄板金属板、例えば板厚が０．１ｍｍ程度のもので構成されている。この構成金属は、導電性と耐食性を備えた金属で、例えば、ステンレス、ニッケル合金、チタン合金等に耐蝕導電処理を施したもの等が挙げられる。
【００２９】
一方の集電部材１４は、横長の矩形の板材からなり、プレス加工によって、複数の凸部１４１が押出し形成されている。これら凸部１４１は、連続する直線状で、板材の縦辺（図示の形態における短辺）に平行に等間隔で、板面を完全に縦断する配置とされ、下部が板厚方向に押し潰されて偏平化されている。これら凸部１４１の偏平化部分１４１’を除く部分の断面形状は、図２では、便宜上大まかに矩形波状断面で示されているが、プレス加工の型抜きの関係から、根元側が若干裾広がりの形状とするのがより実際的である。これら凸部１４１の間に画定され、単位セル１０Ａの空気極１２に面する側が開いた溝状の空間Ｓ１は、後に詳記するように、空気極１２側に空気を流通させる空気流路として使用される。各凸部１４１の頂部１４２の平面は、空気極１２が接触する当接部となっている。また、凸部１４１の裏側に画定される溝状の空間Ｓ２は、同じく後に詳記する冷却空間（本形態では流路）として使用される。そして、これら空気流路Ｓ１と冷却空間Ｓ２を部分的に連通させるべく、集電部材１４を貫通する多数の通孔１４３が形成されている。これら通孔１４３の開設位置は任意であるが、凸部１４１の両側面が常識的である。更に、集電部材１４の横辺（図示の形態における長辺）方向の両端部近傍には、縦方向に長い長円孔１４４が形成されている。この長円孔１４４は、集電部材１４を集電部材１５と枠体１６，１７とに重ねてセパレータ１０Ｂを積層した場合に、これら各部材を整合して貫通する水素流路Ｌ１，Ｌ２を構成する。
【００３０】
他方の集電部材１５は、集電部材１４と合致する矩形の板材からなり、プレス加工によって、複数の凸部１５１が押出し形成されている。凸部１５１は、頂部１５２が平坦で、断面形状も、先の凸部１４１の場合と同様に実質上矩形波状とされているが、この形態の場合の凸部１５１は、縦方向に間欠的に設けられている。すなわち、凸部１５１は、横方向（長辺方向）の配設ピッチを集電部材１４の凸部１４１の配設ピッチに合わせ、縦方向（短辺方向）の配設ピッチを適宜の間隔とした円形又は矩形の突起とされている。図２における左半分の断面は、これら凸部１５１の配列部分での截断面を表し、右半分の断面は、配列部分間での截断面を表す。これら凸部１５１の間に形成される縦横の空間Ｓ３は、単位セル１０の燃料極１３に面する側が開いた面状の空間を構成し、燃料である水素が流通する水素流路とされる。これら凸部１５１の頂部１５２の平面は、燃料極１３が接触する当接部となっている。また、凸部１５１の裏側は、集電部材１４に面する側が開いた短筒状の空間Ｓ４となっていて、集電部材１４の空間Ｓ２に合わさっており、結果的に冷却空間Ｓ２を介して、両端が板材の長辺部に開口する開口部を備える構成となる。この集電部材１５にも、集電部材１４と同様に長辺方向の両端部近傍に、短辺方向に長い長円孔１５３が形成され、集電部材１４と枠体１５，１６とに重ねてセパレータ１０Ｂを積層した場合に、これら各部材を整合して貫通する水素流路Ｌ１，Ｌ２を構成する。この形態において、凸部１５１を燃料極１３に対して小面積で間欠的に当接する短柱状としているのは、これにより柱状の凸部１５１の間をぬう水素流路Ｓ３が縦横に形成され、水素ガスの流れの滞留やよどみを抑制できることを狙ったものである。また、こうすることで、燃料極１３に対する水素ガスの接触面積が大きくなるので、発電効率の向上も期待できる。
【００３１】
上記の構成からなる集電部材１４，１５は、各凸部１４１，１５１が共に外側となるように重ね合わされて固定される。このとき、凸部１４１，１５１を形成していない板面部分、すなわち水素流路Ｓ３の裏側面と空気流路Ｓ１の裏側面が当接した状態となり、相互に通電可能な状態となる。また、集電部材１４，１５を重ね合わせることによって、それらの間に、空間Ｓ２と空間Ｓ４が合わさった冷却空間が形成される。また、単位セル１０Ａが集電部材１４に合わさることで、空間Ｓ１の開放面側が閉鎖され、管状の空気流路が構成され、この流路を囲む壁の一部が空気極１２で構成されることになる。そしてこの空気流路Ｓ１から、単位セル１０Ａの空気極１２に空気と水が供給される。同様に、単位セル１０Ａが集電部材１５に合わさることで、空間Ｓ３の開放面側が閉鎖され、面状の水素流路が構成され、この流路を囲む壁の一部が燃料極１３で構成されることになる。そしてこの燃料流路Ｓ３から、単位セル１０Ａの燃料極１３に水素が供給される。
【００３２】
前記の構成からなる集電部材１４，１５には、枠体１６，１７がそれぞれ重ねられる。図３及び図４に示すように、集電部材１４に重ねられる枠体１６は、集電部材１４と実質上同じ外形形状とされ、両側の縦枠部１６１を上下の横枠部１６２，１６３で連結した構造とされ、下方の横枠部１６３は、両側の縦枠部１６１の下辺及び集電部材１４，１５の下辺と面一にならないように、これらの下辺より横枠部１６３の下辺が上方に位置するように全体を若干上方にずらした位置に配置されている。これらの枠で囲まれる中央には、集電部材１４の凸部１４１を収納する窓１６４が画定されている。また、この枠体１６にも、その両端部近傍に、集電部材１４の長円孔１４４に合致する位置及び形状の長円孔１６５が形成されている。枠体１６の横枠部１６２，１６３と、これらが連結される部分の縦枠部１６１は、縦枠部１６１全体の厚さより薄肉とされ、これらの肉厚の関係から、集電部材１４が重ねられる側の面の横枠部１６２，１６３は、集電部材１４の凸部形成範囲に対応する位置で、短辺方向全体に渡って集電部材１４との当接面より後退した面を形成している。したがって、枠体１６が集電部材１４に重ねられた状態では、集電部材１４の凸部１４１は、窓１６４内では単位セル１０Ａの空気極１２に接触し、横枠部１６２，１６３に対峙する部分では、それらに当接する関係となる。かくして、集電部材１４と枠体１６との間には、上部で集電部材１４の凸部１４１と横枠部１６２の内側面、窓１６４部で集電部材１４の凸部１４１と単位セル１０Ａの空気極１２面、下部で集電部材１４の凸部１４１と横枠部１６３の内側面で囲われた多数の管状空間として、縦方向に全通する空気流路が画定される。
【００３３】
集電部材１５に重ねられる枠体１７は、枠体１６より縦方向寸法の短い枠状に構成され、この場合、本体部分１７０には、窓１７１より横方向に大きな開口が形成されている。この開口の高さは、窓１７１の高さを画定するが、開口の幅は、集電部材１５の両端の長円孔１５３の外端間の幅に合致する幅とされている。そして、この開口の幅方向両端の近傍に、一対の縦枠部１７２が設けられている。この両縦枠部１７２に挟まれる幅が窓１７１の横幅を画定し、両縦枠部１７２と本体部分１７０の開口の幅とで画定される幅が、集電部材１５の両端の長円孔１５３の横幅に合致する寸法とされ、実質的に長円孔１５３の位置と形状に合致する長孔１７３が構成されている。縦枠部１７２は、本体部分１７０より薄肉とされ、これらの肉厚の関係から、集電部材１５が重ねられる側の面の縦枠部１７２が設けられた位置で、集電部材１５の凸部１５１の高さに相当する分だけ、当接面より後退した面を形成している。したがって、枠体１７が集電部材１５に重ねられた状態では、集電部材１５の凸部１５１は、縦枠部１７２では縦枠部１７２に当接し、窓１７１内では単位セル１０Ａの燃料極１３に接触する当接関係となる。このようにして長孔１７３に挟まれる部分には、凸部１５１をぬうように一様に形成された面状の水素流路Ｓ３が構成される。
【００３４】
更に図面上には表れていない細部構成について説明すると、望ましくは、冷却空間Ｓ２を構成する流路の断面積を上辺側から下辺側に向かうにしたがって順次小さくなる設定とする。こうした構成を採ることで、冷却空間Ｓ１から空気流路Ｓ２に流れる空気の圧力損失を低減することができる。こうした流路構成は、集電部材１４の凸部１４１の高さあるいは幅又はそれら両方を適宜設定することで実現できる。
【００３５】
また、空気流路Ｓ１及び冷却空間Ｓ２の内壁面には、必要に応じて親水性処理が施される。この処理は、具体的には、内壁表面と水の接触角が４０°以下、好ましくは３０°以下となるような表面処理とされる。処理方法としては、親水処理剤を、表面に塗布する方法が採られる。塗布される処理剤としては、ポリアクリルアミド、ポリウレタン系樹脂、酸化チタン（ＴｉＯ２）等が挙げられる。この他の親水性処理としては、金属表面の粗さを粗化する処理が挙げられる。例えば、プラズマ処理などがその例である。親水性処理は、最も温度が高くなる部位に施すことが好ましく、例えば、単位セル１０Ａに接触している凸部１４１の頂部１４２の裏側の冷却空間内壁表面Ｆ１、凸部１４１表側の空気流路側壁表面Ｆ２と裏側の冷却空間側壁表面Ｆ３、空気流路底面Ｆ４の順で、優先的に処理されていることが望ましい。さらに、冷却空間Ｓ２の一部を構成する凸部１５１の内壁表面Ｆ５にも親水性処理を施してもよい。親水性処理を施すことにより、内壁面の濡れが促進され、水の潜熱冷却による効果が向上する。
【００３６】
以上のように構成された枠体１６，１７によって集電部材１４，１５を保持してセパレータ１０Ｂが構成され、セパレータ１０Ｂと単位セル１０Ａを交互に積層して、燃料電池スタック１が構成される。こうして積層された燃料電池スタック１の上面には、図２に示すように、多数の空気流路Ｓ１の開口と、冷却空間Ｓ２の開口が交互に隣接して横方向に並び、枠体１７と枠体１６の横枠部１６２の厚さを合わせた分の間隔を置いて、同配列の開口が積層方向に並んだ空気と水の取入れ部が構成される。また、燃料電池スタック１の下面にも、同様の配列の空気と水の排出部が構成される。
【００３７】
本発明の主題に係る構成は、この水の排出部に適用されている。図３に示すセパレータの縦断面及び図５に示すセパレータの底面を参照して、冷却空間Ｓ２の排出部に、該排出部に溜まる液体水を緩徐に排出する排出規制手段が設けられている。この排出規制手段は、排出部を液体水により封止して空気の排出を妨げるものである。この形態では、排出規制手段は、冷却空間Ｓ２の排出部を構成する流路の断面積を、所定の長さに渡って狭窄させた流路狭窄部Ｓ２’とされている。図示の流路狭窄部Ｓ２’は、流路構成部材が薄板金属板のプレス品であることから、プレス成形された凸部１４１を、凸部の内側に所定の空間が残る程度に板面方向に押し潰して偏平化部分１４１’を形成することで構成されている。
【００３８】
このように冷却手段の冷却空間Ｓ２の下部に形成された排出部に、セパレータ１０Ｂの他の部分に対して隔絶させて水切り部Ｓ２”が形成されている。この水切り部Ｓ２”とセパレータ１０Ｂの他の部分との隔絶は、概括的には、水切り部Ｓ２”の下端面１４ａ，１５ａとセパレータ１０Ｂの他の部分の下端面１６３ａ，１７０ａとの不連続によりなされている。この形態においては、水切り部Ｓ２”とセパレータ１０Ｂの他の部分との隔絶は、水切り部Ｓ２”の下端面１４ａ，１５ａとセパレータ１０Ｂの他の部分の下端面１６３ａ，１７０ａとの面位置の上下方向のずれによりなされている。
【００３９】
より具体的には、本形態において、セパレータ１０Ｂは、空気流路Ｓ１と冷却空間Ｓ２を画成する空間画成部材としての集電部材１４，１５と、該空間画成部材に添設された枠体１６，１７を備えることから、冷却空間Ｓ２の排出部に沿う枠体部分、すなわち横枠部１６３と枠体１７の下方の横枠部１７０が、冷却空間Ｓ２の排出部の下端より上部で終端して、排出部における水切り部Ｓ２”を枠体１６，１７から下端面１６３ａ，１７０ａ位置をずらす形態で隔絶している。なお、枠体１６の両側の縦枠部１６１の下端面１６１ａは、水切り部Ｓ２”の下端面１４ａ，１５ａと同位置にあるが、冷却空間Ｓ２の各排出部とは離れているため、水切りの支障にはならない。こうして、水切り部Ｓ２”は、冷却空間Ｓ２の排出部を構成する流路の断面積を、所定の長さに渡って狭窄させた流路狭窄部Ｓ２’の下端で構成される。
【００４０】
こうした構成からなる燃料電池スタックは、その各単電池に空気と水及び水素を供給することで、図６に模式化して示すように作動する。この形態の場合、空気と水は、スタックの上面から一様に供給されることから、空気流路Ｓ１には直接水が入らないように、空気流路Ｓ１の開口部は蓋１８で閉栓されているものとする。なお、空気流路Ｓ１と冷却空間Ｓ２に分離した供給を行なう形式では、空気流路Ｓ１側には空気のみが供給されるようにすれば、必ずしも空気流路Ｓ１の閉栓は必要としない。図示のように、冷却空間Ｓ２に供給される空気と水は、空気流中に水滴が霧状に混入した状態（以下この状態を混合流という）で冷却空間の上部に入る。燃料電池の定常運転状態では、単位セル１０Ａが反応により発熱しているため、冷却空間Ｓ２内の混合流が加熱される。混合流中の水滴は、親水性処理により冷却空間Ｓ２壁面に付着し、加熱により蒸発して壁面から熱を奪う潜熱冷却作用が生じる。こうして蒸気となった水は、図に網掛けの矢印で示すように、通孔１４３から図に白抜き矢印で流れを示す空気と共に空気流路Ｓ１に入り、単位セル１０Ａの空気極１２側に付着し、空気極１２を湿潤させる。そして、空気流路Ｓ１に入った余剰の空気と蒸気は、燃料電池スタックの下方の空気流路Ｓ１の下部開口から排出される。
【００４１】
これに対して、空気流路Ｓ１に入らなかった空気と水は、そのままでは燃料電池スタックの下方の冷却空間Ｓ２の下部開口から排出されることになるが、流路狭窄部Ｓ２’の作用で、壁を伝って流下する液体水状態の水が流路狭窄部に至って滞留することで毛細管現象により流路を塞ぐ現象が生じ、この水が冷却空間Ｓ２からの空気の直接の排出を妨げる作用をする。したがって、冷却空間Ｓ２に供給された空気は、実質上全て空気流路Ｓ１に送り込まれてから、空気流路を経て燃料電池スタックから排出されるようになる。また、空気に対する閉栓機能を果たす液体水は、流路狭窄部に滞留する最下部の水が上部の水に押され、水切り部Ｓ２”から離れるときに水滴となって落下することで順次排水される。この際、水切り部Ｓ２”がその周囲部分に対して隔絶されていることで、周囲部分に回り込んで水膜となり、排水の落下を妨げる状態の発生が回避される。
【００４２】
一方、燃料流路Ｓ３への水素の供給は、各単電池１０の両側をそれらの積層方向に貫く水素流路Ｌ１，Ｌ２（図２参照）の一方から、縦枠部１７２と凸部１５１の間の空間を通して、それにつながる燃料流路Ｓ３から行なわれる。これにより単位セル１０Ａの燃料極１３への水素の供給が行なわれる。この燃料極１３側では、燃料流路Ｓ３に入った余剰の水素は、反対側の水素流路に排出され、この水素流路につながるシステムの配管により排出又は回収される。
【００４３】
前記のような作用から、この形態の場合、冷却空間Ｓ２の排出部の水切り部Ｓ２”が枠体１６の横枠部下面１６３ａや枠体１７の横枠部下面１７０ａに対して隔絶されていることで、排水が水切り部Ｓ２”から枠体１６の横枠部下面１６３ａや枠体１７の横枠部下面１７０ａに回り込んでセパレータの下面に水膜を形成することがなくなり、各水切り部Ｓ２”から水滴化して落下することで順次排出されるため、冷却空間Ｓ２に隣接する空気流路Ｓ１を水膜で塞ぐことがなくなり、空気流路Ｓ１からの排気を促進することができる。
【００４４】
また、水切り部Ｓ２”の枠体１６，１７に対する隔絶が、流路画成部材としての導電部材１４，１５に対する枠体１６，１７の上下方向寸法設定のみでなされているため、枠体１６，１７に格別の加工を施すことなく、水切り部Ｓ２”の隔絶が単純な構成で実現されている。更に、水切り部Ｓ２”を流路狭窄部Ｓ２’の下端に形成しているため、冷却空間Ｓ２の流路狭窄部Ｓ２’に溜まる液体水による空気封止機能を得ながら、水切り部Ｓ２”を小さな面積のものとすることができ、周囲と隔絶した水切り部Ｓ２”での水切りが一層確実に行なわれるようになる。しかも、このように水切り部Ｓ２”を小さな面積のものとすることで、その分だけ隣接する空気流路Ｓ１の排気部の開口面積を広げることができるため、水切り部Ｓ２”の隔絶と相俟って、空気流路Ｓ１の排気部への液体水の回り込みによる閉鎖を一層確実に防ぐことができる。更に、セパレータの薄肉化に伴い極細長い空間となる冷却空間Ｓ２からの排水が安定的に行なわれ、同様の理由から極細長い流路となる隣接する空気流路Ｓ１からの排気も冷却空間Ｓ２の排出部からの水の回り込みにより阻害されることなく、円滑に行なわれる効果が得られる。この結果、燃料電池の発電性能が向上する。
【００４５】
以上、本発明の理解のために実施形態を例示したが、本発明は例示の実施形態に限定されるものではなく、特許請求の範囲に記載の事項の範囲内で、種々に具体的構成を変更して実施可能なものである。
【００４６】
【発明の効果】
本発明の請求項１に記載の構成によれば、冷却空間の排出部の水切り部が周囲に対して隔絶されていることで、排水が水切り部から周囲に回り込んで水膜となることなく、水滴化して落下することで順次排出されるため、水膜がセパレータの底面に形成されて冷却空間に隣接する空気流路を水膜で塞ぐことがなくなり、空気流路からの排気を阻害するのを防ぐことができる。
【００４７】
また、請求項２に記載の発明によれば、水切り部の下端面とセパレータの他の部分の下端面との不連続によりセパレータ下面の面位置の連続による水膜の形成が阻害されるため、水切り部からセパレータの他の部分への排水の回り込みが少なくなり、排水の水滴化による水切り部からの落下が安定的に生じるようになる。
【００４８】
更に、請求項３に記載の発明によれば、水切り部の下端面とセパレータの他の部分の段差によりセパレータ下面の面位置の一致による水膜の形成が阻害されるため、排水がセパレータの他の部分に多少回り込んだ場合でも、水切り部とつながった水膜の形成が防止される。
【００４９】
また、請求項４に記載の構成によれば、流路画成部材に対する枠体の上下方向寸法設定のみで水切り部の他の隣接部分に対する隔絶が可能となるため、枠体に格別の加工を施すことなく、冷却空間からの排水の水切りを行なうことができる。
【００５０】
次に、請求項５に記載の構成によれば、水切り部を小さな面積のものとすることができるため、周囲と隔絶した水切り部での水切りが一層確実に行なわれるようになる。
【００５１】
また、請求項６に記載の構成によれば、冷却空間の流路狭窄部に溜まる液体水による空気封止機能を得ながら、液体水を安定的に排水することができる。しかも、水切り部を小さな面積のものとすることができ、その分だけ隣接する空気流路の排気部の開口面積を広げることができるため、水切り部の隔絶と相俟って、空気流路の排気部への液体水の回り込みによる閉鎖を一層確実に防ぐことができる。
【００５２】
更に、請求項７に記載の構成によれば、セパレータの薄肉化に伴い極細長い空間となる冷却空間からの排水が安定的に行なわれ、同様の理由から極細長い流路となる隣接する空気流路からの排気も冷却空間の排出部からの水の回り込みにより阻害されることなく、円滑に行なわれる効果が得られる。この結果、燃料電池の発電性能が向上する。
【図面の簡単な説明】
【図１】本発明の適用に係る燃料電池システムの構成図である。
【図２】本発明の実施形態に係る単電池の部分横断面図である。
【図３】実施形態の単電池の縦断面図である。
【図４】実施形態の単電池を構成するセパレータの分解斜視図である。
【図５】実施形態に係る単電池を下方から見て水切り部の構成を示す部分底面図である。
【図６】実施形態のセパレータによる冷却と排水のメカニズムを示す模式図である。
【符号の説明】
１０Ａ　単位セル
１０Ｂ　セパレータ
１２　空気極
１４，１５　導電部材（空間画成部材）
１６，１７　枠体
１４３　連通孔
Ｓ１　空気流路
Ｓ２　冷却空間（冷却手段）
Ｓ２’　流路狭窄部
Ｓ２”　水切り部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell, and more particularly to a fuel cell cooling technique using a separator interposed between unit cells of the fuel cell.
[0002]
[Prior art]
A unit cell of a PEM fuel cell as one type of fuel cell includes a fuel electrode (generally referred to as a hydrogen electrode because hydrogen gas is used as fuel) and an oxidant electrode (also a gas containing oxygen as an oxidant). Since a certain air is used, this is hereinafter referred to as an air electrode) and a solid polymer electrolyte membrane is sandwiched between the two. Each of the fuel electrode and the air electrode includes a catalyst layer containing a catalyst substance, and an electrode base material that supports the catalyst layer and has a function of transmitting a reaction gas. Further outside the fuel electrode and the air electrode, a gas flow path (generally, an electrode) for supplying hydrogen and air as reactant gas uniformly from the outside of the cell to the electrode surface and discharging an excess of the reactant gas outside the cell. Separator (connector plate) provided with a groove having an open surface side) is laminated. This separator prevents gas permeation and performs current collection for taking out the generated current to the outside. The unit cell and the separator as described above constitute one unit cell.
[0003]
In an actual fuel cell, a large number of such unit cells are stacked in series to form a stack. In such a fuel cell, in order to maintain sufficient power generation efficiency, it is necessary to keep the polymer solid electrolyte membrane in the unit cell in a sufficiently wet state. Generally, only water generated by the electrolytic reaction causes moisture to be generated. Because of the shortage, means for supplying humidified water to each unit cell is required. In addition, since the amount of heat substantially corresponding to the generated electric power is generated by the electrolytic reaction, a cooling means for preventing the fuel cell body from excessively heating up is provided.
[0004]
Various types of fuel cell cooling means have been conventionally proposed. As one of these methods, a configuration is adopted in which a nozzle for jetting water is provided in an air manifold for sending air as an oxidant to the air electrode, and water is jetted into the air sent to the gas flow path and mixed in advance. In some cases, cooling is performed using latent heat generated when water evaporates by heating in a gas flow path. In this method, water, which must be supplied to the cell because it is necessary to keep the unit cell wet, is supplied along with the flow of air that also needs to be supplied to the air electrode side. It is based on the idea that it is reasonable to use this water for cooling.
[0005]
In the fuel cell system adopting the above-described method, the applicant has disclosed in Japanese Patent Application No. 2002-54839 according to the earlier application that the air in which water is injected and mixed in the air manifold is connected to the communication space from the cooling space formed in the separator. To supply air to the air flow path. In this method, the unit cells are cooled by the latent heat of water evaporating by the heat of the unit cells transmitted to the cooling space, and the vaporized water is supplied to the air flow path together with the air. Thereby, while cooling the unit cell via the separator, the blockage of the flow path due to the intrusion of liquid water or mist-like water into the air flow path is prevented. That is, in the case of the fuel cell device having the above-described structure, the air and water supplied to the cooling space are used for latent heat cooling of the heat generated during power generation of the fuel cell. Then, a part of the water supplied in a liquid state evaporates in the cooling space and is supplied together with the air as water vapor from the communication hole to the air flow path, the air is used for the reaction of the fuel cell, and the water vapor is humidified. Used for
[0006]
When adopting the above-mentioned supply method, it is important to supply the air that has entered the cooling space to the air flow path without loss, and the liquid water that has not entered the cooling space and has not become water vapor is also smoothly discharged from the cooling space. Emissions are also important. For this reason, the applicant has filed Japanese Patent Application No. 2002-196597 in the lower part of the cooling space (normally, air is supplied to the unit cell from the inlet side of the cooling space opened at the cell upper part). Therefore, a configuration is proposed in which liquid water accumulated in the air discharge section is located at the lowermost portion of the cell always stays in an appropriate amount in the discharge section, thereby functioning as a stopper for preventing air from directly flowing out of the cooling space. I have.
[0007]
[Problems to be solved by the invention]
By the way, in the case of the configuration in which the liquid water in the cooling space functions as a stopper as described above, it is necessary to keep the amount of liquid water retained in the discharge unit constant while preventing the overflow of the water into the air flow path. It is important to keep. For this purpose, it is important that the water to be sequentially discharged from the discharge unit is smoothly dripped from the cell. However, if there is a member adjacent to the periphery of the discharge unit located at the bottom of the cell, this member is used. The discharged water wraps around the surface and spreads in a film form from the mouth of the discharge part to the adjacent part thereof, which becomes a factor to hinder the dripping of water (separation of water droplets from the cell).
[0008]
Also, when the separator is made thin for compactness of the cell, the cooling space and the air flow path defined therein are also very fine spaces, so the liquid water in the cooling space functions as a stopper as described above. It is important not only for the configuration to perform the drainage but also to properly drain the water from the discharge part of the cooling space in terms of preventing the exhaust from the adjacent air flow path.
[0009]
In order to solve the above-described problems, the present invention promotes the dripping of water from a discharge part of a cooling space in a separator to prevent the drainage and exhaust from being hindered due to the flow of the discharged water to an adjacent part. Aim.
[0010]
[Means for Solving the Problems]
The object is to provide a fuel cell in which a separator is arranged between unit cells adjacent to each other, wherein the separator is provided on an air flow path provided on at least a surface side in contact with an air electrode of the unit cell, and provided on a back side. A cooling space for supplying air and water through the cooling space, and cooling means for cooling the unit cells by latent heat of water evaporated by heat of the unit cells transmitted to the cooling space. This is attained by a configuration in which a drain portion is formed in the formed discharge portion so as to be isolated from other portions of the separator. In this configuration, the separation between the drain portion and the other portion of the separator is specifically performed by discontinuity between the lower end surface of the drain portion and the lower end surface of the other portion of the separator. More specifically, the separation between the draining part and the other part of the separator is made by a vertical displacement of the surface position between the lower end face of the draining part and the lower end face of the other part of the separator.
[0011]
In the above configuration, the separator includes a space defining member that defines an air flow path and a cooling space, and a frame attached to the space defining member, and a frame portion along a discharge portion of the cooling space. However, it terminates above the lower end of the discharge part of the cooling space, and separates the drain part in the discharge part from the frame. In this case, the drainage part can be constituted by the lower end of the flow path narrowing part in which the cross-sectional area of the flow path constituting the discharge part of the cooling space is narrowed over a predetermined length. Further, the cooling space is communicated with an adjacent air flow path through a communication hole of the separator, and the flow path narrowing section seals a discharge section with liquid water accumulated in the flow path narrowing section to discharge air. It can be a hindrance. Further, the space defining member of the separator is formed by bringing a pair of plate members made of a press-formed product of a conductive metal plate material into contact with each other in a plate surface direction, and defining a cooling space between both plate members. It can also be made.
[0012]
[Action]
In the configuration according to the first aspect, the water supplied to the cooling space together with the air and not vaporized or condensed after vaporization to form water droplets and reaches the discharge portion temporarily stays in the discharge portion as liquid water. The water located at the lowermost part of the water is not discharged from the isolated drain part to the surroundings to form a water film, but instead drops into water droplets, and is discharged sequentially.
[0013]
Next, with the configuration according to claim 2, since the lower end surface of the draining portion is separated by discontinuity with respect to another adjacent surface, the formation of water droplets at the lower end surface of the draining portion is promoted, It becomes easy to drip from the draining part.
[0014]
Similarly, in the configuration according to the third aspect, the lower end surface of the draining portion is separated by a vertical displacement with respect to the surface position of the other adjacent surface, so that water discharged from the lower end surface of the draining portion becomes droplets. Is promoted, and it becomes easy to drip from the draining part.
[0015]
Next, in the configuration according to claim 4, the drainage portion of the discharge portion defined by the space defining member surrounding the cooling space projects downward from the frame portion along the discharge portion, so that the drainage portion with respect to the frame portion. As a result, the surface constituting the drainage portion is limited to a very small area on the lower surface of the space defining member, and the formation of water droplets at the lower end surface of the drainage portion is further promoted.
[0016]
Further, according to the configuration of the fifth aspect, the draining portion is the lower end of the flow path constricted portion narrowed with respect to the cooling space, so that the surface constituting the draining portion is limited to a smaller area, and the draining portion is limited. The formation of water droplets at the lower end face of the part is further promoted.
[0017]
Further, according to the structure of the sixth aspect, the liquid water stays as columnar droplets in the narrow portion of the flow path forming the discharge part of the cooling space, and this gradually closes the discharge part while closing the flow path. As a result, a continuous sealing effect against air is exerted, and the water draining part becomes the lower end of the flow path constricted part narrowed with respect to the cooling space, so that the surface constituting the water draining part is formed. In addition, since the area is limited to a smaller area with respect to the exhaust portion of the air flow path, and the formation of water droplets of the discharged water at the lower end surface of the drain section is further promoted, the exhaust from the air flow path is also promoted.
[0018]
According to the configuration of the seventh aspect, each of the above-described functions can be produced in the case where the separator is a press-formed product for reducing the thickness.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows a configuration example of a vehicle fuel cell system according to an application of the present invention. This system includes a fuel cell stack 1, a fuel supply system (shown by a two-dot chain line) 2 for supplying hydrogen as fuel to the fuel cell stack 1, and air for supplying oxidizing gas to the fuel cell stack 1. An air supply system (shown by a dashed-dotted line in the figure) 3, a water supply system (shown by a solid line in the figure) 4 for supplying water mainly for cooling to required parts of the system including the fuel cell stack 1, and power generation. It comprises an electric load system (shown by a broken line in the figure) 5 as a load.
[0020]
The fuel cell stack 1 is configured by stacking a large number of plate-shaped unit cells in the plate thickness direction. As shown in a horizontal cross section in FIG. 2 and a vertical cross section in FIG. 3, the unit cell 10 includes a unit cell 10A and a separator 10B. For convenience of description, FIG. 2 also shows adjacent unit cells, and FIG. 3 does not show the unit cells. The unit cell 10A has a solid polymer electrolyte membrane 11 sandwiched between an air electrode 12 and a fuel electrode 13, and the separator 10B has a two-piece thin plate, although a detailed structure thereof will be described later. The four metal plates 14 and 15 are surrounded by insulator frames 16 and 17. The separator 10B is formed with hydrogen passages L1 and L2 communicating with the hydrogen supply passage 20 of the fuel supply system 2 and an air passage S1 communicating with the air manifold 34 of the air supply system 3 via the cooling space S2. The fuel cell stack 1 is disposed in a housing connected to the air manifold 34 with the hydrogen flow paths L1 and L2 oriented horizontally and the air flow path S1 oriented vertically.
[0021]
The fuel supply system 2 is configured as a storage unit 21 of hydrogen using a hydrogen storage alloy as a fuel, and the supply pressure to the fuel cell stack 1 is reduced in the middle of a hydrogen supply path 20 connecting the storage unit 21 and the fuel cell stack 1. A hydrogen pressure regulating valve 23 for adjustment and a hydrogen supply solenoid valve 24 for controlling supply cutoff are interposed in series. In connection with the fuel supply system 2, the fuel cell stack 1 is provided with a hydrogen exhaust path 27 for extracting hydrogen therefrom as needed, and in the middle thereof, a hydrogen exhaust solenoid valve 29 for opening and closing the exhaust path, A hydrogen exhaust check valve 28 for preventing the intake of outside air is interposed. The hydrogen supply path 20 is provided with a hydrogen primary pressure sensor 22 and a secondary pressure sensor 25 for measuring gas pressures before and after pressure regulation by a hydrogen pressure regulating valve 23.
[0022]
The air supply system 3 includes a duct in which an air supply fan 31 that sends outside air to the air manifold 34 via a filter and a heater is arranged, a duct that connects the fuel cell stack 1 to the storage unit 21 of the hydrogen storage alloy, and a storage unit 21. It is composed of a duct connecting the water condenser 46 and a discharge path for discharging used air from the water condenser 46 through a filter to the outside air. The air supply system 3 further includes an intake air temperature sensor 32 that monitors the temperature of air supplied to the fuel cell stack 1 upstream of an air supply fan for operating a heater as needed, An exhaust temperature sensor 37 attached to the downstream duct and monitoring the temperature of the air exhausted from the fuel cell stack 1 is also provided.
[0023]
The water supply system 4 supplies the water sent from the water tank 40 by the water injection pump 41 to the air manifold 34 by the water injection nozzle 45 around the water tank 40, and supplies the water to the hydrogen storage alloy in the storage unit 21. The circulation path is configured to directly return to the water tank 40 water supplied by the storage nozzle 46 and collected and generated by the fuel cell stack 1 and water generated by condensation in the water condenser 46. In the middle of the water passage from the water injection pump 41 constituting the supply side of the circulation path to the water injection nozzle 45, a direct injection water electromagnetic valve 43 for adjusting the injection amount is interposed, and a nozzle is provided on the suction side of the water injection pump 41. A filter 42 for preventing clogging of 45 is inserted. Similarly, a storage solenoid valve 47 for adjusting the injection amount is inserted in the middle of the water passage from the water injection pump 41 to the storage nozzle 46. The recovery side of the circulation path includes a water path returning from the fuel cell stack 1 to the water tank 40, and a water path returning from the water condenser 46 to the water tank 40 via the pump 44. The water tank 40 is provided with a water temperature sensor 47 and a water level sensor 48, so that the water temperature and the water level of the tank can be monitored.
[0024]
The electric load system 5 of the fuel cell is constituted by a lead wire connected from the fuel cell stack 1 via the relay 53 to the inverter 51 for controlling the motor 52. In this system, a secondary battery composed of a storage battery is used as a driving power source for ancillary equipment such as an air supply fan 31, a water condenser 46 fan, a water injection pump 41, a water tank 40 freezing countermeasure heater, and various solenoid valves of a fuel cell device. A battery 54 is provided, and the secondary battery 54 is connected in parallel to the fuel cell. This secondary battery 54 is used for accumulating the regenerative current of the motor 52 and for supplementing the output when the output of the fuel cell is insufficient.
[0025]
In the fuel cell system having such a configuration, the hydrogen supply electromagnetic valve 24 is closed, and hydrogen is stored in the hydrogen storage alloy by the supply of hydrogen gas from a filling path (not shown). The supply of water to the water supply system 4 is performed by opening the water supply electromagnetic valve 48 and supplying water to the water tank 40. Then, in the power generation state, the hydrogen supply solenoid valve 24 is opened to supply the hydrogen occluded in the hydrogen storage alloy under the pressure regulation by the hydrogen pressure regulating valve 23 to the fuel cell stack 1 while the air supply fan 31 is activated, An operation of sending air to the fuel cell stack 1 via the air manifold 34 is performed. In this power generation state, the direct injection water electromagnetic valve 43 is opened while operating the water direct injection pump 41 of the water supply system 4 continuously or intermittently as necessary, and water is injected from the water injection nozzle 45 into the air manifold 34. As a result, an operation of mixing water into the air supplied to the fuel cell stack 1 in a mist state is performed. This water enters the cooling space S2 from the upper opening of the cooling space S2 of each separator of the fuel cell stack 1 together with the air, is vaporized, and is supplied to the air electrode 12 side of each unit cell through the air flow path S1. Are discharged to the lower part of the housing from the lower opening constituting the discharge part of the cooling space S2, and collected in the water tank 40.
[0026]
The air and the water in the water vapor state, which are sent to the fuel cell stack 1 and heated by the fuel cell stack 1 as described above, enter the storage 21 of the hydrogen storage alloy via the duct from the lower portion of the housing, and After being heated, the air is guided to a water condenser 46 through a duct, and is separated into dry air and condensed water. The dried air is discharged to the outside air through a filter, and the condensed water is passed through a pump 44 to a water tank. Return to 40. Further, the water that has passed through the fuel cell stack 1 in a liquid state returns directly to the water tank 40.
[0027]
The feature of this system is that the air flow path S1 and the cooling space S2 in the fuel cell stack 1 can be arranged in a unified distribution path, and air and water can be distributed at the same time. There is no need to provide.
[0028]
Next, a detailed configuration of the separator 10B inserted between the unit cells 10A of each unit cell 10 of the fuel cell stack 1 will be described. As shown in FIG. 4 in a disassembled state, the separator 10B includes a pair of current collectors for contacting the air electrode 12 and the fuel electrode 13 (see FIG. 2) of the unit cell 10A to take out current. 14 and 15 and frames 16 and 17 that are superimposed on them and support the unit cell 10A. In this embodiment, the current collecting members 14 and 15 are formed of a thin metal plate, for example, having a plate thickness of about 0.1 mm. The constituent metal is a metal having conductivity and corrosion resistance, for example, a metal obtained by subjecting a stainless steel, a nickel alloy, a titanium alloy, or the like to a corrosion resistance conductive treatment.
[0029]
One current collecting member 14 is made of a horizontally long rectangular plate material, and a plurality of convex portions 141 are formed by extrusion by pressing. These convex portions 141 are arranged in a continuous straight line, and are arranged so as to be completely vertical to the plate surface at equal intervals in parallel with the vertical sides (short sides in the illustrated form) of the plate material, and the lower portion is crushed in the plate thickness direction. Has been flattened. In FIG. 2, the cross-sectional shape of the convex portion 141 excluding the flattened portion 141 ′ is roughly shown as a rectangular wave-shaped cross section for convenience. The shape is more practical. The groove-shaped space S1 defined between the protrusions 141 and having an open side facing the air electrode 12 of the unit cell 10A serves as an air flow path for flowing air to the air electrode 12 as described later in detail. used. The plane of the top 142 of each convex portion 141 is a contact portion with which the air electrode 12 contacts. The groove-shaped space S2 defined on the back side of the convex portion 141 is used as a cooling space (flow path in this embodiment), which will be described later in detail. A large number of through holes 143 that penetrate the current collecting member 14 are formed so that the air flow path S1 and the cooling space S2 partially communicate with each other. The opening positions of these through holes 143 are arbitrary, but both side surfaces of the convex portion 141 are common sense. Further, long elliptical holes 144 that are long in the vertical direction are formed near both ends in the horizontal side (long side in the illustrated form) direction of the current collecting member 14. When the separator 10B is laminated by stacking the current collecting member 14 on the current collecting member 15 and the frames 16 and 17, the oblong holes 144 define the hydrogen passages L1 and L2 that align and penetrate these members. Constitute.
[0030]
The other current collecting member 15 is formed of a rectangular plate that matches the current collecting member 14, and has a plurality of protrusions 151 formed by extrusion by press working. The convex portion 151 has a flat top 152 and a substantially rectangular cross-sectional shape similarly to the case of the convex portion 141, but the convex portion 151 in this case is intermittent in the vertical direction. It is provided in. In other words, the protrusions 151 are arranged such that the horizontal (longer side) pitch is aligned with the pitch of the convexes 141 of the current collector 14, and the vertical (short side) pitch is set to an appropriate interval. It is a round or rectangular projection. The left half section in FIG. 2 shows a cut section at the arrangement portion of the projections 151, and the right half section shows a cut section at the arrangement portion. The vertical and horizontal spaces S3 formed between the projections 151 constitute a planar space whose side facing the fuel electrode 13 of the unit cell 10 is open, and is a hydrogen flow path through which hydrogen as fuel flows. . The plane of the top 152 of the projection 151 serves as a contact portion with which the fuel electrode 13 contacts. Further, the rear side of the convex portion 151 is a short cylindrical space S4 in which the side facing the current collecting member 14 is open, and is fitted to the space S2 of the current collecting member 14, and as a result, the cooling space S2 is interposed. Thus, a configuration is provided in which both ends are open to the long side of the plate material. Like the current collecting member 14, the current collecting member 15 also has a long oval hole 153 formed in the short side direction near both ends in the long side direction, and is overlapped with the current collecting member 14 and the frames 15 and 16. When the separators 10B are stacked together, the hydrogen passages L1 and L2 are formed to penetrate these members in alignment. In this embodiment, the convex portion 151 has a short columnar shape that intermittently abuts on the fuel electrode 13 with a small area, thereby forming a hydrogen passage S3 vertically and horizontally between the columnar convex portions 151, The purpose is to suppress stagnation and stagnation of the flow of hydrogen gas. In addition, since the contact area of the hydrogen gas with the fuel electrode 13 is increased by doing so, improvement in power generation efficiency can be expected.
[0031]
The current collecting members 14 and 15 having the above-described configuration are overlapped and fixed such that the respective convex portions 141 and 151 are both on the outside. At this time, the plate surface portion on which the convex portions 141 and 151 are not formed, that is, the back surface of the hydrogen flow path S3 and the back surface of the air flow path S1 are in contact with each other, and are in a state where they can be energized mutually. Further, by overlapping the current collecting members 14 and 15, a cooling space in which the space S2 and the space S4 are combined is formed between them. When the unit cell 10A is fitted to the current collecting member 14, the open surface side of the space S1 is closed to form a tubular air flow path, and a part of the wall surrounding the flow path is formed by the air electrode 12. Will be. Then, air and water are supplied from the air flow path S1 to the air electrode 12 of the unit cell 10A. Similarly, when the unit cell 10A is fitted to the current collecting member 15, the open surface side of the space S3 is closed to form a planar hydrogen flow path, and a part of the wall surrounding the flow path is formed by the fuel electrode 13. Will be done. Then, hydrogen is supplied from the fuel passage S3 to the fuel electrode 13 of the unit cell 10A.
[0032]
Frames 16 and 17 are respectively superposed on the current collecting members 14 and 15 having the above-described configuration. As shown in FIGS. 3 and 4, the frame 16 superposed on the current collecting member 14 has substantially the same outer shape as that of the current collecting member 14, and the vertical frame 161 on both sides is divided into upper and lower horizontal frame portions 162, 163. The lower horizontal frame portion 163 is lower than the lower side of the horizontal frame portion 163 so as not to be flush with the lower sides of the vertical frame portions 161 and the current collecting members 14 and 15 on both sides. Are slightly shifted upward so as to be positioned upward. At the center surrounded by these frames, a window 164 for accommodating the convex portion 141 of the current collecting member 14 is defined. Also, the frame body 16 is formed with oval holes 165 at positions and shapes corresponding to the oval holes 144 of the current collecting member 14 near both ends. The horizontal frame portions 162 and 163 of the frame body 16 and the vertical frame portion 161 of the portion to which they are connected are made thinner than the entire vertical frame portion 161. The horizontal frame portions 162 and 163 on the surface on which the power is collected are located at positions corresponding to the convex portion forming range of the current collecting member 14, and the surface retreated from the contact surface with the current collecting member 14 over the entire short side direction. Has formed. Therefore, when the frame 16 is overlaid on the current collecting member 14, the convex portion 141 of the current collecting member 14 contacts the air electrode 12 of the unit cell 10 A in the window 164 and faces the horizontal frame portions 162 and 163. In the part that does, it has a relationship that abuts them. Thus, between the current collecting member 14 and the frame 16, the convex portion 141 of the current collecting member 14 and the inner surface of the horizontal frame portion 162 are located at the upper part, and the convex portion 141 of the current collecting member 14 is located at the window 164. As a large number of tubular spaces surrounded by the convex portion 141 of the current collecting member 14 and the inner side surface of the horizontal frame portion 163 on the lower surface of the air electrode 12 of 10A, a vertical air flow path is defined.
[0033]
The frame 17 superimposed on the current collecting member 15 is formed in a frame shape having a smaller vertical dimension than the frame 16, and in this case, an opening larger than the window 171 is formed in the main body 170 in the lateral direction. The height of this opening defines the height of the window 171, and the width of the opening is set to a width that matches the width between the outer ends of the oblong holes 153 at both ends of the current collecting member 15. A pair of vertical frame portions 172 are provided near both ends of the opening in the width direction. The width between the vertical frame portions 172 defines the width of the window 171, and the width defined by the vertical frame portions 172 and the width of the opening of the main body portion 170 is an oblong hole at both ends of the current collecting member 15. An elongated hole 173 having a size matching the width of the elongated hole 153 and substantially matching the position and shape of the elongated hole 153 is formed. The vertical frame portion 172 is made thinner than the main body portion 170. Due to the relationship between the thicknesses, the vertical frame portion 172 is provided at the position where the vertical frame portion 172 is provided on the surface on which the current collecting member 15 is overlapped. A surface that is recessed from the contact surface by an amount corresponding to the height of the portion 151 is formed. Therefore, when the frame 17 is superimposed on the current collecting member 15, the projection 151 of the current collecting member 15 contacts the vertical frame 172 in the vertical frame 172, and the fuel electrode of the unit cell 10 A in the window 171. 13 comes into contact. In the portion sandwiched between the long holes 173 in this manner, a planar hydrogen flow path S3 that is uniformly formed so as to cover the projection 151 is formed.
[0034]
Further, a detailed configuration not shown in the drawings will be described. Preferably, the cross-sectional area of the flow path forming the cooling space S2 is set to gradually decrease from the upper side to the lower side. With such a configuration, the pressure loss of the air flowing from the cooling space S1 to the air flow path S2 can be reduced. Such a flow path configuration can be realized by appropriately setting the height and / or width of the convex portion 141 of the current collecting member 14.
[0035]
In addition, hydrophilic processing is performed on the inner wall surfaces of the air passage S1 and the cooling space S2 as necessary. Specifically, this treatment is performed such that the contact angle between the inner wall surface and water is 40 ° or less, preferably 30 ° or less. As a treatment method, a method of applying a hydrophilic treatment agent to the surface is employed. Examples of the treatment agent to be applied include polyacrylamide, polyurethane resin, titanium oxide (TiO2), and the like. As another hydrophilic treatment, a treatment for roughening the roughness of the metal surface may be mentioned. For example, plasma processing is an example. The hydrophilic treatment is preferably performed on a portion where the temperature is highest. For example, the cooling space inner wall surface F1 on the back side of the top 142 of the protrusion 141 in contact with the unit cell 10A, and the air flow path on the front side of the protrusion 141 It is desirable that the processing is preferentially performed in the order of the side wall surface F2, the back side cooling space side wall surface F3, and the air flow path bottom surface F4. Further, the inner wall surface F5 of the projection 151 constituting a part of the cooling space S2 may be subjected to a hydrophilic treatment. By performing the hydrophilic treatment, wetting of the inner wall surface is promoted, and the effect of the latent heat cooling of water is improved.
[0036]
The separators 10B are configured by holding the current collecting members 14 and 15 by the frames 16 and 17 configured as described above, and the fuel cell stack 1 is configured by alternately stacking the separators 10B and the unit cells 10A. . As shown in FIG. 2, on the upper surface of the fuel cell stack 1 thus stacked, openings of a large number of air flow passages S1 and openings of the cooling space S2 are alternately arranged side by side in a lateral direction. An air and water intake section having openings of the same arrangement arranged in the stacking direction is formed at intervals corresponding to the thickness of the horizontal frame section 162 of the frame body 16. Further, the air and water discharge units having the same arrangement are also formed on the lower surface of the fuel cell stack 1.
[0037]
The arrangement according to the subject of the invention is applied to this water outlet. With reference to the vertical cross section of the separator shown in FIG. 3 and the bottom surface of the separator shown in FIG. 5, the discharge portion of the cooling space S2 is provided with a discharge regulating means for slowly discharging the liquid water accumulated in the discharge portion. This discharge restricting means seals the discharge portion with liquid water to prevent discharge of air. In this embodiment, the discharge restricting means is a flow passage narrowing portion S2 'in which the cross-sectional area of the flow passage forming the discharge portion of the cooling space S2 is narrowed over a predetermined length. The flow path constricted portion S2 ′ shown in the drawing is formed by pressing the convex part 141 formed by pressing the thin metal plate into the sheet surface direction such that a predetermined space remains inside the convex part because the flow path constituent member is a pressed product of a thin metal plate. To form a flattened portion 141 '.
[0038]
A drain portion S2 "is formed at a discharge portion formed below the cooling space S2 of the cooling means so as to be isolated from other portions of the separator 10B. The drain portion S2" and the separator 10B are separated from each other. The separation from the other portions is generally performed by discontinuity between the lower end surfaces 14a and 15a of the drainer S2 ″ and the lower end surfaces 163a and 170a of the other portions of the separator 10B. The separation between the drainer S2 "and the other part of the separator 10B is made by a vertical displacement of the surface position between the lower end surfaces 14a and 15a of the drainer S2" and the lower end surfaces 163a and 170a of the other part of the separator 10B. ing.
[0039]
More specifically, in the present embodiment, the separator 10B is provided with the current collecting members 14 and 15 as space defining members for defining the air flow path S1 and the cooling space S2, and is attached to the space defining member. Since the frame members 16 and 17 are provided, the frame portion along the discharge portion of the cooling space S2, that is, the horizontal frame portion 163 and the horizontal frame portion 170 below the frame member 17 are located above the lower end of the discharge portion of the cooling space S2. To terminate the draining portion S2 ″ in the discharge portion from the frames 16, 17 by shifting the lower end surfaces 163a, 170a. The lower end surfaces 161a of the vertical frame portions 161 on both sides of the frame 16 are separated. Is located at the same position as the lower end surfaces 14a and 15a of the draining portion S2 ″, but does not hinder draining because it is separated from the discharge portions of the cooling space S2. In this way, the draining section S2 ″ is formed by the lower end of the channel narrowing section S2 ′ in which the cross-sectional area of the channel forming the discharge section of the cooling space S2 is narrowed over a predetermined length.
[0040]
The fuel cell stack having such a configuration operates as schematically shown in FIG. 6 by supplying air, water, and hydrogen to each unit cell. In this case, since the air and water are uniformly supplied from the upper surface of the stack, the opening of the air flow path S1 is closed with a lid 18 so that water does not directly enter the air flow path S1. It is assumed that Note that, in the type in which the supply is separately performed to the air flow path S1 and the cooling space S2, it is not always necessary to close the air flow path S1 if only the air is supplied to the air flow path S1 side. As shown in the drawing, the air and water supplied to the cooling space S2 enter the upper portion of the cooling space in a state where water droplets are mixed in a mist state in the air flow (hereinafter, this state is referred to as a mixed flow). In the steady operation state of the fuel cell, the mixed flow in the cooling space S2 is heated because the unit cell 10A generates heat by the reaction. The water droplets in the mixed flow adhere to the wall surface of the cooling space S2 by the hydrophilic treatment, and evaporate by heating to generate a latent heat cooling effect of removing heat from the wall surface. The water that has thus become steam enters the air flow path S1 together with the air whose flow is indicated by the outline arrow in the figure as shown by the shaded arrow in the figure, as shown by the shaded arrow in the figure, and flows to the air electrode 12 side of the unit cell 10A. It adheres and wets the cathode 12. Excess air and steam entering the air flow path S1 are discharged from the lower opening of the air flow path S1 below the fuel cell stack.
[0041]
On the other hand, the air and water which have not entered the air flow path S1 are discharged as they are from the lower opening of the cooling space S2 below the fuel cell stack, but due to the action of the flow path narrowing portion S2 '. When the liquid water flowing down the wall reaches the flow path narrowing portion and stays there, a phenomenon of blocking the flow path due to a capillary phenomenon occurs, and this water prevents the direct discharge of air from the cooling space S2. do. Therefore, substantially all of the air supplied to the cooling space S2 is sent into the air passage S1, and then discharged from the fuel cell stack through the air passage. In addition, the liquid water that fulfills the function of plugging air is drained sequentially by the lowermost water staying in the channel narrowing part being pushed by the upper water and dropping as water drops when leaving the draining part S2 ″. At this time, since the draining portion S2 "is isolated from the surrounding portion, it is possible to avoid a situation in which the draining portion S2" wraps around the surrounding portion and forms a water film, thereby preventing the drainage from dropping.
[0042]
On the other hand, the supply of hydrogen to the fuel flow path S3 is performed by using one of the hydrogen flow paths L1 and L2 (see FIG. 2) penetrating both sides of each unit cell 10 in their stacking direction. It is performed from the fuel flow path S3 connected to it through the space between them. Thus, hydrogen is supplied to the fuel electrode 13 of the unit cell 10A. On the fuel electrode 13 side, surplus hydrogen that has entered the fuel flow path S3 is discharged to the opposite hydrogen flow path, and is discharged or recovered by a system pipe connected to the hydrogen flow path.
[0043]
Due to the above-described operation, in this case, the draining portion S2 ″ of the discharge portion of the cooling space S2 is isolated from the horizontal frame portion lower surface 163a of the frame 16 and the horizontal frame portion lower surface 170a of the frame body 17. As a result, the drainage does not flow from the drain portion S2 ″ to the horizontal frame lower surface 163a of the frame 16 or the horizontal frame lower surface 170a of the frame 17 to form a water film on the lower surface of the separator. , And are sequentially discharged by falling into water droplets, so that the air flow path S1 adjacent to the cooling space S2 is not blocked by the water film, and exhaust from the air flow path S1 can be promoted.
[0044]
In addition, since the separation of the drainer S2 ″ from the frames 16 and 17 is performed only by setting the vertical dimension of the frames 16 and 17 with respect to the conductive members 14 and 15 as flow path defining members, the frame 16, 16 The isolation of the draining portion S2 ″ is realized with a simple configuration without performing any special processing on 17. Furthermore, since the water draining part S2 "is formed at the lower end of the flow path narrowing part S2 ', the water draining part S2" is formed while obtaining the air sealing function by the liquid water accumulated in the flow path narrowing part S2' of the cooling space S2. It is possible to make the drainage portion S2 "having a small area, so that drainage at the drainage portion S2" isolated from the surroundings can be performed more reliably. In addition, by making the drainage portion S2 "having a small area, Since the opening area of the exhaust portion of the adjacent air flow path S1 can be increased by that amount, the closing of the drainage portion S2 ″ by the spillage of the liquid water to the exhaust portion of the air flow path S1 can be achieved in conjunction with the isolation of the drain portion S2 ″. Further, the drainage from the cooling space S2, which is an extremely thin space as the separator is thinned, is stably performed, and for the same reason, the adjacent air passage S1 which becomes an extremely thin passage. Cooling exhaust from Without being obstructed by the diffraction of water from the discharge portion between S2, the effect of smoothly performed is obtained. As a result, improved power generation performance of the fuel cell.
[0045]
As described above, the embodiments have been exemplified for the understanding of the present invention. However, the present invention is not limited to the illustrated embodiments, and various specific configurations may be adopted within the scope of the claims. It can be implemented with modification.
[0046]
【The invention's effect】
According to the configuration described in claim 1 of the present invention, the drainage part of the discharge part of the cooling space is isolated from the surroundings, so that the drainage does not go around from the drainage part to the surroundings and form a water film. Since the water film is sequentially discharged by falling into water droplets, a water film is formed on the bottom surface of the separator, so that the air flow path adjacent to the cooling space is not blocked by the water film, and the exhaust from the air flow path is obstructed. Can be prevented.
[0047]
According to the second aspect of the present invention, the discontinuity between the lower end surface of the draining portion and the lower end surface of the other portion of the separator hinders formation of a water film due to continuation of the surface position of the separator lower surface. The sewage of the drainage from the drainage part to the other part of the separator is reduced, and the waterfall of the drainage from the drainage part due to water droplets is stably generated.
[0048]
Further, according to the third aspect of the present invention, the step between the lower end surface of the drainer and the other portion of the separator prevents the formation of a water film due to the coincidence of the surface position of the lower surface of the separator. Even if it slightly enters the portion, the formation of a water film connected to the draining portion is prevented.
[0049]
Further, according to the configuration of the fourth aspect, since only the vertical dimension setting of the frame with respect to the flow path defining member can be separated from other adjacent portions of the drainage portion, special processing is performed on the frame. Without draining, drainage of the drainage from the cooling space can be performed.
[0050]
Next, according to the configuration of the fifth aspect, since the water draining portion can be made to have a small area, the water draining at the water draining portion isolated from the surroundings can be performed more reliably.
[0051]
Further, according to the configuration of the sixth aspect, the liquid water can be drained stably while obtaining an air sealing function by the liquid water accumulated in the flow path constricted portion of the cooling space. In addition, the drain section can have a small area, and the opening area of the exhaust section of the adjacent air flow path can be increased by that much. It is possible to more reliably prevent the liquid water from flowing around to the exhaust part.
[0052]
Furthermore, according to the configuration of the seventh aspect, the drainage from the cooling space, which becomes an ultra-slim space as the thickness of the separator is reduced, is stably performed, and for the same reason, the adjacent air flow that becomes an ultra-slim flow path. The effect that the exhaust from the road is performed smoothly without being hindered by the flow of the water from the exhaust portion of the cooling space is obtained. As a result, the power generation performance of the fuel cell is improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fuel cell system according to an application of the present invention.
FIG. 2 is a partial cross-sectional view of a unit cell according to an embodiment of the present invention.
FIG. 3 is a longitudinal sectional view of the unit cell of the embodiment.
FIG. 4 is an exploded perspective view of a separator constituting the unit cell of the embodiment.
FIG. 5 is a partial bottom view showing the configuration of a drain section when the unit cell according to the embodiment is viewed from below.
FIG. 6 is a schematic diagram showing a mechanism of cooling and draining by the separator of the embodiment.
[Explanation of symbols]
10A Unit cell 10B Separator 12 Air electrode 14, 15 Conductive member (space defining member)
16, 17 Frame 143 Communication hole S1 Air flow path S2 Cooling space (cooling means)
S2 'Channel narrowing part S2 "Drainage part

Claims

In a fuel cell in which a separator is arranged between adjacent unit cells,
The separator includes an air flow path provided on at least a surface side of the unit cell in contact with the air electrode, and a cooling space provided on the back side and supplied with air and water, and the unit cell transmitted to the cooling space. Cooling means for cooling the unit cells by latent heat of water evaporated by heat of
A fuel cell, wherein a drain portion formed at a lower portion of a cooling space of the cooling means is separated from other portions of the separator.

2. The fuel cell according to claim 1, wherein the separation between the draining portion and another portion of the separator is made by discontinuity between a lower end surface of the draining portion and a lower end surface of another portion of the separator.

3. The fuel according to claim 1, wherein the separation between the draining portion and another portion of the separator is performed by a vertical displacement of a surface position between a lower end surface of the draining portion and a lower end surface of the other portion of the separator. 4. battery.

The separator includes a space defining member that defines an air flow path and a cooling space, and a frame attached to the space defining member, and a frame portion along a discharge portion of the cooling space is a part of the cooling space. 4. The fuel cell according to claim 1, wherein the water drain portion in the discharge portion is separated from the frame by terminating above a lower end of the discharge portion. 5.

5. The drainage unit according to claim 1, wherein a cross-sectional area of a flow path that forms a discharge part of the cooling space is formed by a lower end of a flow path constricted part that is constricted over a predetermined length. The fuel cell according to the item.

The cooling space communicates with an adjacent air flow path through a communication hole of the separator, and the flow path constriction seals a discharge part with liquid water accumulated in the flow path constriction to prevent discharge of air. The fuel cell according to claim 5, wherein

The space defining member of the separator is formed by bringing a pair of plate members made of a press-formed product of a conductive metal plate material into contact with each other in a plate surface direction, and defines a cooling space between both plate members. The fuel cell according to claim 4, 5 or 6.