JP3699052B2

JP3699052B2 - Hydrogen remaining amount detection method and apparatus

Info

Publication number: JP3699052B2
Application number: JP2002073772A
Authority: JP
Inventors: 勝廣寺尾; 孝海老沢; 徹真下
Original assignee: Japan Steel Works Ltd
Current assignee: Japan Steel Works Ltd
Priority date: 2002-03-18
Filing date: 2002-03-18
Publication date: 2005-09-28
Anticipated expiration: 2022-03-18
Also published as: JP2003270190A

Description

【０００１】
【発明の属する技術分野】
本発明は、水素残量検出方法及びその装置に関するものであり、詳しくは水素貯蔵タンクに収容した水素貯蔵物質の水素残量を検出する方法及びその装置に関するものである。
【０００２】
【従来の技術及びその課題】
この種の従来の水素残量検出装置として、水素貯蔵タンク内の水素貯蔵物質の水素吸蔵に伴う体積変化を静電容量式のレベルセンサによつて検出すると共に、この体積変化から水素貯蔵物質の水素吸蔵量を演算し、水素残量を表示するものが知られている（特許第３１４７９６８号）。
【０００３】
これは、水素貯蔵物質が水素を吸蔵するに従つて結晶格子が膨張して体積が増加する性質を利用し、水素貯蔵物質の体積（嵩）を検出して水素残量を推定する。すなわち、電極板が粉粒状の水素貯蔵物質の中に部分的に埋没し得る静電容量式レベルセンサを使用し、表面を絶縁被覆された２枚の電極板の間に存在する水素貯蔵物質の量に応じて変化する静電容量を検出回路により検出し、かつ、水素残量に変換して、表示部へ出力する。
【０００４】
水素を水素貯蔵タンクに充填するとき、熱交換器に冷水を流して水素貯蔵タンク内の水素貯蔵物質を冷却しながら、高圧水素ボンベからの水素をレギュレータによつて減圧させてタンクに導入すると、タンク内の金属（合金）からなる水素貯蔵物質は金属水素化物に変化することによつて水素を吸蔵し、その際に水素貯蔵物質の粒子自体が膨張するので、粉粒体の堆積レベルが上昇する。
【０００５】
従つて、電極板の間に存在する水素貯蔵物質の体積が増加し、電極板の埋没量が増えるので、電極板の間の静電容量が増加する、としている。静電容量は、検出回路によつて電気信号に変換され、かつ、水素残量と静電容量との関係をもとに水素残量に換算され、表示部に表示される。
【０００６】
このように、従来の水素残量検出装置は、水素貯蔵物質の水素貯蔵に伴う体積変化を水素貯蔵量に変換するものではあるが、水素貯蔵物質中に水素が吸収されたときの格子の膨張に伴う水素貯蔵物質の体積変化によつて、水素貯蔵タンク内の水素貯蔵物質の表面の高さが変化することを利用して、静電容量の変化を検出している。
【０００７】
このため、この水素残量検出装置では、長期間にわたつて正確な水素残量を測定することが容易でないという技術的課題を有している。すなわち、水素貯蔵物質は水素の吸収によつて単位格子の体積が２０〜３０％膨張することに起因して、微粉化現象が生じ、また、その粒度は吸放出の繰り返しによつて、より細かくなることが知られている。そして、水素の繰り返し吸放出に伴う粒度変化は、水素貯蔵物質自体の嵩密度を低下させ、体積が増える現象を引き起こす。このため、単純な水素吸蔵による体積膨張だけを検出することができず、長期間にわたつて正確な水素残量を測定することができない。長期間にわたつて水素残量を正確に測定するためには、水素貯蔵物質の微粉化に伴う表面高さの変化に基づく静電容量の検出値を補正する必要があり、水素残量が零のときにリセットするなどの作業を伴う。
【０００８】
加えて、水素残量検出装置は、水素貯蔵物質と接触状態で部分的に埋設し得るように配設するので、水素貯蔵物質を収容する水素貯蔵タンクの内部に配置する必要がある。そのため、水素貯蔵タンク内に収容する水素貯蔵物質の量を制限し、所要の空間部を必ず確保して水素残量検出装置を設けなければならず、設計自由度に劣る。
【０００９】
また、従来の水素残量検出装置として、水素貯蔵時の水素貯蔵物質の電気抵抗の変化を貯蔵量に変換する方法（特開平４−１０４０３７）、水素貯蔵時の水素貯蔵物質の温度変化を貯蔵量に変換する方法（特開平２−１９８３４６）、及び水素貯蔵タンクの圧力変化を直接読み取る方法（特開平６−１９３４８０）も知られている。
【００１０】
しかしながら、水素貯蔵物質の電気抵抗の変化を貯蔵量に変換する方法にあつては、電流が流れるために水素貯蔵物質の薄膜等からなる抵抗体が連続体でなければならないが、水素貯蔵物質は水素の吸・放出を繰り返すと体積膨張により微粉化し連続性が失われてしまう。これにより、断線状態になつたり、電極の剥離が起こることで電流が流れなくなり、電気抵抗を測定できなくなる、という不具合が生じてしまう。
【００１１】
水素貯蔵時の水素貯蔵物質の温度変化を貯蔵量に変換する方法にあつては、水素貯蔵物質が水素を吸収するときに発熱し、放出するときに放熱するため、これらのときには温度変化が明確に起こるが、ある温度で放出を止めれば反応が起こらなくなり温度変化も生じなくなる。従つて、水素貯蔵物質中の水素を連続的に吸・放出しているときには温度によつて水素残量をモニターできるが、スタート・ストップを繰り返すような場合にはモニターできなくなり、発熱量を積算するなどの工夫が必要となり、好ましくない。
【００１２】
また、水素貯蔵タンクの圧力変化を直接読み取る方法にあつては、水素貯蔵物質が固溶状態から水素化物を除々に生成していく過程で固溶と水素化物相とが混在した状態のとき、所定の圧力で平衡圧が一定となる長いプラトー領域をもつことから、その範囲では圧力が一定となり、検出できなくなる。このため、圧力変化が顕著になるプラトー圧の両側、つまりほぼ水素化物のみとなる満タン状態の検出とほぼ固溶のみとなる残量が少ない状態の検出しかできない。但し、水素貯蔵物質の組成を少し変えることでこのプラトー圧に傾きをもたせることができ、この場合には、プラトー領域においても直接水素残量を検出可能になるが、傾きが少ない場合には検出に精度が求められ、逆に傾きが多い場合には水素貯蔵物質の性能悪化になるのであまり好ましくない。
【００１３】
本発明は、上記のような従来技術の課題を解決するためになされたものであり、特に、水素貯蔵のために水素貯蔵タンク内に収容する水素貯蔵物質の単純な水素貯蔵に伴う体積変化によつて電極の埋没量の変化を生じさせ、この電極の埋没量の変化から静電容量の変化を検出し、水素残量を求める方法に代えて、検出用水素貯蔵物質を用い、検出用水素貯蔵物質の水素吸蔵に伴う膨張量を一対の電極の間隔変化による静電容量の変化に利用することにより、嵩密度変化が抑制されて精度に優れる静電容量式の水素残量検出方法及びその装置を提供することを目的としている。
【００１４】
【課題を解決するための手段】
本発明は、このような従来の技術的課題に鑑みてなされたもので、その構成は、次の通りである。
請求項１の発明は、水素貯蔵タンク１の内部に収容する水素貯蔵物質２の水素残量検出方法であつて、
該水素貯蔵タンク１内に設ける一対の支持部１５のそれぞれに、検出用水素貯蔵物質１６ａと水素透過性を有するゴム質弾性体１６ｂとを混合した混合成形体１６を介して電極１７を支持させ、水素貯蔵タンク１の空間部１ａに対向配置させる一対の該電極１７間の静電容量を検出し、各混合成形体１６の所定の体積変化状態での静電容量の値から水素残量を検出することを特徴とする水素残量検出方法である。
請求項２の発明は、水素貯蔵物質２を収容する水素貯蔵タンク１の内部に配置され、水素貯蔵物質２の水素残量を検出する水素残量検出装置であつて、
該水素残量検出装置が、水素貯蔵タンク１内に設ける一対の支持部１５と、水素貯蔵タンク１の空間部１ａに対向配置される一対の電極１７と、検出用水素貯蔵物質１６ａと水素透過性を有するゴム質弾性体１６ｂとを混合した混合成形体１６とを有し、対応する支持部１５と電極１７とを混合成形体１６によつて連結して形成され、
各混合成形体１６の所定の体積変化状態での一対の電極１７間の静電容量の値から水素残量を検出することを特徴とする水素残量検出装置である。
請求項３の発明は、検出用水素貯蔵物質１６ａが、水素貯蔵タンク１に収容する水素貯蔵物質２と同一種類であることを特徴とする請求項２の水素残量検出装置である。
請求項４の発明は、検出用水素貯蔵物質１６ａが、水素貯蔵タンク１に収容する水素貯蔵物質２と異なる種類であることを特徴とする請求項２の水素残量検出装置である。
【００１５】
【発明の実施の形態】
図１〜図３は、本発明に係る水素残量検出装置の１実施の形態を示す。図１中において符号１は水素貯蔵タンクを示し、タンク１の内部には、粉粒状の合金からなる水素貯蔵物質２が所定量収容され、一部（図上で上部）に空間部１ａを形成している。水素貯蔵タンク１には、空間部１ａに位置させて、バルブ４及びレギュレータ２４を備える水素流入ライン５並びにバルブ７及びレギュレータ２７を備える水素放出ライン８の一端が接続されている。バルブ７の開放によつて水素放出ライン８から流出した水素ガスは、レギュレータ２７によつて圧力（又は流量）が調節されながら水素利用装置９、例えば燃料電池、エンジン等に供給されて消費される。水素流入ライン５の他端は、水素ボンベや炭化水素の改質システム等からなる水素源１０に接続され、バルブ４の開放により、水素源１０内の水素ガスがレギュレータ２４によつて圧力（又は流量）が調節されながら水素流入ライン５を通じてタンク１内に流入し、水素貯蔵物質２に補給される。
【００１６】
このため、水素貯蔵タンク１には内部を可及的均一に加熱及び冷却する加熱・冷却手段１２が付属され、加熱・冷却手段１２によつて水素貯蔵物質２を所定温度に加熱することにより、水素貯蔵物質２から水素を放出させ、また、加熱・冷却手段１２によつて水素貯蔵物質２を所定温度に冷却することにより、水素貯蔵物質２に水素を吸蔵させることができるようになつている。但し、水素貯蔵物質２が、大気との熱交換で水素放出の熱量がまかなえる場合は、加熱手段を省略することができ、また、大気との熱交換で水素吸蔵の熱量がまかなえる場合は、冷却手段を省略することができる。
【００１７】
この水素貯蔵タンク１の空間部１ａには、水素貯蔵物質２と常時、つまり水素貯蔵物質２が充分に水素を吸蔵して結晶格子が膨張して体積が増加した状態であつても、非接触状態となるように水素残量検出装置１４を設ける。水素残量検出装置１４は、図２に示すように一対の支持部１５と、各支持部１５に対応する混合成形体１６及び板状の電極１７とを有し、対応する支持部１５と電極１７とを混合成形体１６によつて連結している。一対の電極１７は、水素貯蔵タンク１の空間部１ａに所定間隔にて対向配置され、対応する支持部１５に、混合成形体１６を介して支持されている。
【００１８】
一対の支持部１５は、対向させて本体１５ａに突設され、本体１５ａが水素貯蔵タンク１の開口部に気密に固設されている。混合成形体１６は、粉粒状の合金からなる検出用水素貯蔵物質１６ａと水素透過性を有するゴム質弾性体１６ｂの原料とを混合させて形成したものであり、水素透過性を有するエラストマー又は天然ゴムに水素貯蔵物質２と同種の検出用水素貯蔵物質１６ａを混合させて練り合わせ、所定厚さの矩形、円形等の任意断面形状に成形・固化させたものである。
【００１９】
ゴム質弾性体１６ｂとしては、水素透過性の点からシリコーンゴムが適しているが、エラストマー又は天然ゴムを広く採用することができる。各ゴム質弾性体１６ｂは、複数に分割させ、水素ガスとの接触面積を増加させることもできる。更に、連通孔を有する多孔質体からなるゴム質弾性体１６ｂとして、水素ガスとの接触面積を増加させることも可能であり、ゴム質弾性体１６ｂの原料に粉粒状の合金からなる検出用水素貯蔵物質１６ａを混合させて練り合わせた後に発泡させ、可及的に小さな連通孔を有する多孔質体からなるゴム質弾性体１６ｂを成形・固化させ、検出用水素貯蔵物質１６ａに至る水素透過を促してもよい。
【００２０】
合金からなる検出用水素貯蔵物質１６ａは導電性を有しているから、支持部１５との絶縁を図るために、必要に応じて電極１７の背面に絶縁コーティング１６ｃを設けることができる。但し、ゴム質弾性体１６ｂに含ませる検出用水素貯蔵物質１６ａの量にもよるが、ゴム質弾性体１６ｂ自体に電極１７と支持部１５との間の絶縁を図る機能を与え、或いは本体１５ａ又は支持部１５を電気絶縁体によつて形成すれば、絶縁コーティング１６ｃを省略することができる。また、水素残量検出装置１４は水素貯蔵タンク１内に水素貯蔵物質２と非接触状態で設けるものであるから、水素貯蔵物質２の付着を防止するために、電極１７の対向する表面には絶縁コーティング１６ｃを設けることは必須ではない。
【００２１】
各電極１７には、リード線１９によつて接続する検出手段１８を介して表示部２０が接続され、コンデンサーとして機能する一対の電極１７間の静電容量を検出回路１８によつて電気的諸量として検出し、水素残量に変換する演算を行なつた後、水素貯蔵物質２に吸蔵された水素の残量として表示部２０に表示する。リード線１９は、気密を保持して本体１５ａを貫通している。
【００２２】
混合成形体１６及び電極１７は、水素透過性を有するカバー１３にて覆い、飛散する水素貯蔵物質２の電極１７への付着に伴うショートを防止することができる。カバー１３は、一対の支持部１５に架設状態として支持部１５の下面部のみならず側面部にも設け、電極１７の周囲の全てをカバー１３、本体１５ａ及び支持部１５によつて覆うことができる。
【００２３】
次に、作用について説明する。水素貯蔵タンク１内の水素貯蔵物質２に充分に水素ガスが吸蔵された状態で、加熱・冷却手段１２によつて水素貯蔵物質２を所定温度に加熱して水素貯蔵物質２から水素を放出させ、水素放出ライン８から水素利用装置９に水素ガスを供給し、水素が消費されると、水素貯蔵物質２の水素吸蔵量が次第に減少する。このとき、加熱・冷却手段１２によつて水素貯蔵タンク１内が可及的均一な所定温度に加熱されているから、空間部１ａに位置する水素残量検出装置１４の検出用水素貯蔵物質１６ａもほぼ同様の温度環境下にある。従つて、水素貯蔵物質２の水素吸蔵量が減少すると、水素貯蔵タンク１の空間部１ａに配置した水素残量検出装置１４の検出用水素貯蔵物質１６ａの水素吸蔵量も同様に減少する。
【００２４】
これにより、検出用水素貯蔵物質１６ａの体積が減少し、ゴム質弾性体１６ｂが固化時に戻るように弾性的に収縮するので、混合成形体１６が収縮し、一対の電極１７の間隔が拡大する。一対の電極１７間の静電容量は、電極１７の間隔に反比例するから、一対の電極１７の間隔の拡大により、電極１７間の静電容量が小さくなる。なお、例えば燃料電池に水素を供給する場合、その消費は少量であり、水素貯蔵物質２の体積変動が緩徐になされるため、水素透過性を有するゴム質弾性体１６ｂを介してなされる検出用水素貯蔵物質１６ａの体積変動も、時間的遅れをほとんど生ずることなく、追従してなされる。
【００２５】
加熱・冷却手段１２によつて水素貯蔵物質２を所定温度に冷却しながら、水素源１０内の水素ガスを水素流入ライン５を通じてタンク１内の水素貯蔵物質２に補給すれば、水素貯蔵物質２の水素吸蔵量が次第に増加し、水素貯蔵タンク１の空間部１ａに配置した水素残量検出装置１４の検出用水素貯蔵物質１６ａの水素吸蔵量も同様に増加する。これにより、検出用水素貯蔵物質１６ａの体積が増大し、ゴム質弾性体１６ｂが弾性的に膨張するので、混合成形体１６が膨張し、一対の電極１７の間隔が縮小する。この一対の電極１７の間隔の縮小により、静電容量が大きくなる。かくして、各混合成形体１６の所定の体積変化状態での静電容量の値から、水素貯蔵物質２の水素残量を検出することができる。なお、ゴム質弾性体１６ｂに連通孔を設ける場合には、検出用水素貯蔵物質１６ａの体積増大に伴うゴム質弾性体１６ｂの弾性的膨張（伸張）を完全には阻害しない程度に設ける。
【００２６】
ところで、静電容量の大きさは、電極１７の表面積、雰囲気ガス（電極１７間の物質の比誘電率）及び電極１７の間隔（距離）によつて定まるが、この場合、常時、水素貯蔵タンク１の空間部１ａに位置して水素貯蔵タンク１の内部に収容する水素貯蔵物質２に接触しない電極１７の表面積及び雰囲気ガス（水素）は同じで変化しないから、電極１７の間隔の変化によつて静電容量が変化する。
【００２７】
ガス透過性に優れるゴム質弾性体１６ｂは、検出用水素貯蔵物質１６ａの粉粒体に対してゴム質の保形材として機能する。このため、水素吸蔵に伴う検出用水素貯蔵物質１６ａの膨張を原因とする崩壊現象（微粉化現象）は、見かけ上、物質１６ａのヒビ割れのようになつて止まるので、検出用水素貯蔵物質１６ａが堆積して密集状態にないこととも相まつて、嵩密度の変化は実質的に生じない。従つて、再現性良く体積膨張・収縮を繰り返し生じ、静電容量の所定値を精度良く長期間にわたつて検出できるようになる。
【００２８】
勿論、水素残量検出装置１４の少なくとも一対の電極１７は、静電容量を検出可能にするために、常時、水素貯蔵物質２と非接触状態にあるから、水素貯蔵物質２に充分（１００％）に水素ガスが吸蔵された状態でも、非接触状態が維持されている。
【００２９】
一対の電極１７間の静電容量は、検出手段１８によつて検出・演算し、表示部２０に水素貯蔵物質２に吸蔵された水素の残量として表示する。この表示部２０に表示される水素の残量により、水素貯蔵物質２の吸蔵水素量を知つて、水素貯蔵物質２への水素補充時期に達したか否かを知り、水素貯蔵物質２から水素が放出されつくす前に、水素ガスを補充することができる。
【００３０】
すなわち、水素貯蔵タンク１内の水素貯蔵物質２の水素残量と水素残量検出装置１４の静電容量とは、図３に示す関係を有し、水素残量の減少に従つて静電容量が小さくなるので、静電容量の値から水素残量を連続的に検出することができる。従つて、静電容量の値から、水素残量が減少して補給時期がきたことを適時に知つて、水素源１０内の水素ガスを水素流入ライン５を通じて水素貯蔵タンク１内の水素貯蔵物質２に補給することができる。これにより、水素残量が零になり、水素利用装置９に水素が供給されなくなるという不測の事態を回避することができる。
【００３１】
ところで、上記１実施の形態にあつては、検出用水素貯蔵物質１６ａとして水素貯蔵物質２と同種の物質（合金）を使用したが、検出用水素貯蔵物質１６ａは、水素貯蔵物質２の吸蔵水素量に比例して水素を吸蔵できるものが採用可能であり、水素貯蔵物質２と異なる種類の物質（合金）を使用することも可能である。また、水素残量検出装置１４は、水素貯蔵タンク１の空間部１ａに配置したが、水素貯蔵物質２と非接触状態で配設すれば良く、水素貯蔵タンク１に補助タンクを連通状態で設け、この水素貯蔵タンク１内に含まれる補助タンク内に水素残量検出装置１４を配設し、水素貯蔵タンク１内の水素残量を同様に検出することも可能である。
【００３２】
【発明の効果】
以上の説明によつて理解されるように、本発明に係る水素残量検出方法及びその装置によれば、次の効果を奏することができる。
水素貯蔵物質を内部に収容する水素貯蔵タンクにおいて、水素貯蔵物質に貯蔵されている水素の残量を、リアルタイムで、かつ、精度良く検出することが可能になる。
【００３３】
更に、水素残量検出装置は、水素貯蔵物質と非接触状態で配設すると共に、検出用水素貯蔵物質がゴム質弾性体に保持されて嵩密度の変化が良好に防止されているので、水素残量検出装置を水素貯蔵物質と接触状態で配設するものと比較して、接触させることに伴う不具合の全てが解消する。すなわち、水素貯蔵タンク内に収容する水素貯蔵物質の微粉化による体積増加の影響を受けることなく、水素残量を検出することができる。その結果、静電容量の検出値の補正のためにリセットするなどの作業を伴うことなく、長期間、精度良く水素の吸蔵量を検出し、残量を知ることができる。
【００３４】
加えて、水素残量検出装置は、水素貯蔵物質と非接触状態で配設するので、水素貯蔵物質を収容する水素貯蔵タンクの空間部に配置することができるのみならず、水素貯蔵タンクに連通状態で設けた補助タンク内に配設し、水素貯蔵タンク内の水素残量を同様に検出することが可能である。その場合、水素貯蔵タンク内に収容する水素貯蔵物質を制限して、所要の空間部を確保しなくともよく、水素残量検出装置を設ける設計自由度が向上する。
【図面の簡単な説明】
【図１】本発明の１実施の形態に係る水素残量検出装置を示す断面図。
【図２】同じく水素残量検出装置の要部を示す図。
【図３】同じく静電容量−水残量特性を示す線図。
【符号の説明】
１：水素貯蔵タンク、１ａ：空間部、２：水素貯蔵物質、９：水素利用装置、１０：水素源、１３：カバー、１５：支持部、１６：混合成形体、１６ａ：検出用水素貯蔵物質、１６ｂ：ゴム質弾性体、１７：電極。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for detecting the remaining amount of hydrogen, and more particularly to a method and apparatus for detecting the remaining amount of hydrogen in a hydrogen storage material stored in a hydrogen storage tank.
[0002]
[Prior art and problems]
As a conventional hydrogen remaining amount detection device of this type, a volume change accompanying hydrogen occlusion of a hydrogen storage material in a hydrogen storage tank is detected by a capacitance type level sensor. A device that calculates the hydrogen storage amount and displays the remaining amount of hydrogen is known (Japanese Patent No. 3147968).
[0003]
This utilizes the property that the crystal lattice expands and the volume increases as the hydrogen storage material occludes hydrogen, and detects the volume (bulk) of the hydrogen storage material to estimate the remaining amount of hydrogen. That is, a capacitance level sensor that can be partially buried in a granular hydrogen storage material is used, and the amount of the hydrogen storage material existing between the two electrode plates whose surfaces are insulated is coated. The capacitance that changes in response is detected by the detection circuit, converted into the remaining amount of hydrogen, and output to the display unit.
[0004]
When filling the hydrogen storage tank with hydrogen, if the hydrogen storage material in the hydrogen storage tank is cooled by flowing cold water through the heat exchanger and the hydrogen from the high-pressure hydrogen cylinder is decompressed by the regulator and introduced into the tank, The hydrogen storage material consisting of metal (alloy) in the tank absorbs hydrogen by changing to metal hydride, and the hydrogen storage material particles expand at that time, so the accumulation level of the granular material increases. To do.
[0005]
Accordingly, the volume of the hydrogen storage material existing between the electrode plates increases, and the amount of buried electrode plates increases, so that the capacitance between the electrode plates increases. The capacitance is converted into an electric signal by the detection circuit, converted into the remaining amount of hydrogen based on the relationship between the remaining amount of hydrogen and the capacitance, and displayed on the display unit.
[0006]
As described above, the conventional hydrogen remaining amount detection device converts the volume change accompanying hydrogen storage of the hydrogen storage material into the hydrogen storage amount, but the expansion of the lattice when hydrogen is absorbed in the hydrogen storage material. The capacitance change is detected by utilizing the change in the height of the surface of the hydrogen storage material in the hydrogen storage tank due to the volume change of the hydrogen storage material.
[0007]
For this reason, this hydrogen remaining amount detection device has a technical problem that it is not easy to accurately measure the remaining amount of hydrogen over a long period of time. That is, the hydrogen storage material has a pulverization phenomenon due to the expansion of the unit cell volume by 20 to 30% due to the absorption of hydrogen, and the particle size becomes finer due to repeated absorption and release. It is known to be. And the particle size change accompanying repeated absorption and release of hydrogen causes the phenomenon that the bulk density of the hydrogen storage material itself is lowered and the volume is increased. For this reason, only volume expansion due to simple hydrogen storage cannot be detected, and an accurate amount of hydrogen cannot be measured over a long period of time. In order to accurately measure the remaining amount of hydrogen over a long period of time, it is necessary to correct the detected capacitance based on the change in surface height associated with the pulverization of the hydrogen storage material. This is accompanied by work such as resetting.
[0008]
In addition, since the hydrogen remaining amount detection device is arranged so as to be partially embedded in contact with the hydrogen storage material, it is necessary to arrange the hydrogen remaining amount detection device inside the hydrogen storage tank that stores the hydrogen storage material. Therefore, it is necessary to limit the amount of the hydrogen storage material accommodated in the hydrogen storage tank, ensure the required space, and provide the hydrogen remaining amount detection device, which is inferior in design flexibility.
[0009]
Further, as a conventional hydrogen remaining amount detection device, a method for converting a change in electrical resistance of a hydrogen storage material during hydrogen storage into a storage amount (Japanese Patent Laid-Open No. 4-104037), and storing a temperature change of the hydrogen storage material during hydrogen storage A method for converting the amount into a quantity (Japanese Patent Laid-Open No. 2-198346) and a method for directly reading a pressure change in a hydrogen storage tank (Japanese Patent Laid-Open No. 6-193480) are also known.
[0010]
However, in the method of converting the change in the electrical resistance of the hydrogen storage material into the storage amount, a resistor consisting of a thin film of the hydrogen storage material must be a continuum for current to flow. Repeated absorption and release of hydrogen results in pulverization due to volume expansion and loss of continuity. As a result, a disconnection state occurs, or an electrode is peeled off, so that a current does not flow and electric resistance cannot be measured.
[0011]
In the method of converting the temperature change of the hydrogen storage material during hydrogen storage into the storage amount, the hydrogen storage material generates heat when absorbing hydrogen and dissipates heat when released, so the temperature change is clear at these times. However, if the release is stopped at a certain temperature, no reaction occurs and the temperature does not change. Therefore, when the hydrogen in the hydrogen storage material is continuously absorbed and released, the remaining amount of hydrogen can be monitored according to the temperature. However, if the start and stop are repeated, it cannot be monitored and the calorific value is integrated. It is not preferable because it requires some device.
[0012]
In addition, for the method of directly reading the pressure change in the hydrogen storage tank, when the hydrogen storage material is gradually in the process of producing hydride from the solid solution state, the solid solution and the hydride phase are mixed, Since the plateau has a long plateau region where the equilibrium pressure is constant at a predetermined pressure, the pressure is constant in that range and cannot be detected. For this reason, it is only possible to detect both sides of the plateau pressure at which the pressure change becomes significant, that is, a full tank state in which only hydride is present and a state in which the remaining amount that is substantially only in solid solution is small. However, this plateau pressure can be inclined by slightly changing the composition of the hydrogen storage material. In this case, the hydrogen remaining amount can be detected directly in the plateau region, but it is detected when the inclination is small. However, if the accuracy is required and the slope is large, the performance of the hydrogen storage material is deteriorated, which is not preferable.
[0013]
The present invention has been made in order to solve the above-described problems of the prior art, and in particular, to a volume change accompanying simple hydrogen storage of a hydrogen storage material accommodated in a hydrogen storage tank for hydrogen storage. Therefore, instead of the method of generating a change in the amount of buried electrode, detecting the change in capacitance from the change in the amount of buried electrode, and obtaining the remaining amount of hydrogen, a hydrogen storage material for detection is used. Capacitance type hydrogen remaining amount detection method with excellent accuracy by suppressing change in bulk density by utilizing the amount of expansion associated with storage of hydrogen in the storage material for the change in capacitance due to the change in the distance between the pair of electrodes The object is to provide a device.
[0014]
[Means for Solving the Problems]
The present invention has been made in view of such a conventional technical problem, and the configuration thereof is as follows.
The invention of claim 1 is a method for detecting the remaining amount of hydrogen in a hydrogen storage material 2 accommodated in the hydrogen storage tank 1.
The electrode 17 is supported by a pair of support portions 15 provided in the hydrogen storage tank 1 via a mixed molded body 16 in which a hydrogen storage material 16a for detection and a rubber elastic body 16b having hydrogen permeability are mixed. The capacitance between the pair of electrodes 17 disposed opposite to the space 1a of the hydrogen storage tank 1 is detected, and the remaining amount of hydrogen is determined from the capacitance value of each mixed molded body 16 in a predetermined volume change state. This is a method for detecting the remaining amount of hydrogen.
The invention of claim 2 is a hydrogen remaining amount detection device that is disposed inside a hydrogen storage tank 1 that contains the hydrogen storage material 2 and detects the remaining amount of hydrogen in the hydrogen storage material 2.
The hydrogen remaining amount detecting device includes a pair of support portions 15 provided in the hydrogen storage tank 1, a pair of electrodes 17 disposed opposite to the space portion 1a of the hydrogen storage tank 1, a hydrogen storage material for detection 16a, and hydrogen permeation. A mixed molded body 16 mixed with a rubber elastic body 16b having a property, and the corresponding support portion 15 and the electrode 17 are connected by the mixed molded body 16;
The hydrogen remaining amount detection device is characterized in that the remaining amount of hydrogen is detected from the capacitance value between the pair of electrodes 17 in a predetermined volume change state of each mixed molded body 16.
The invention according to claim 3 is the hydrogen remaining amount detection device according to claim 2, wherein the hydrogen storage material for detection 16a is the same type as the hydrogen storage material 2 accommodated in the hydrogen storage tank 1.
The invention of claim 4 is the hydrogen remaining amount detection device according to claim 2, wherein the hydrogen storage material 16a for detection is of a different type from the hydrogen storage material 2 accommodated in the hydrogen storage tank 1.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show an embodiment of a hydrogen remaining amount detection apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a hydrogen storage tank. Inside the tank 1, a predetermined amount of a hydrogen storage material 2 made of a powdered alloy is accommodated, and a space 1a is formed in a part (upper part in the figure). are doing. One end of a hydrogen inflow line 5 including a valve 4 and a regulator 24 and a hydrogen discharge line 8 including a valve 7 and a regulator 27 are connected to the hydrogen storage tank 1 in the space 1a. The hydrogen gas flowing out of the hydrogen discharge line 8 by opening the valve 7 is supplied to the hydrogen utilization device 9, for example, a fuel cell, an engine or the like, while the pressure (or flow rate) is adjusted by the regulator 27. . The other end of the hydrogen inflow line 5 is connected to a hydrogen source 10 composed of a hydrogen cylinder, a hydrocarbon reforming system, and the like. When the valve 4 is opened, the hydrogen gas in the hydrogen source 10 is pressurized by a regulator 24 (or The hydrogen storage material 2 is replenished by flowing into the tank 1 through the hydrogen inflow line 5 while adjusting the flow rate).
[0016]
For this reason, the hydrogen storage tank 1 is provided with heating / cooling means 12 for heating and cooling the inside as uniformly as possible, and by heating the hydrogen storage material 2 to a predetermined temperature by the heating / cooling means 12, Hydrogen is released from the hydrogen storage material 2, and the hydrogen storage material 2 is cooled to a predetermined temperature by the heating / cooling means 12, so that the hydrogen storage material 2 can occlude hydrogen. . However, the heating means can be omitted when the hydrogen storage material 2 can cover the heat of hydrogen release by heat exchange with the atmosphere, and it can be cooled if the heat storage of the hydrogen storage material 2 can cover the amount of hydrogen storage by heat exchange with the atmosphere Means can be omitted.
[0017]
The space 1a of the hydrogen storage tank 1 is not contacted with the hydrogen storage material 2 at all times, that is, even when the hydrogen storage material 2 sufficiently occludes hydrogen and the crystal lattice expands to increase its volume. A hydrogen remaining amount detection device 14 is provided so as to be in a state. As shown in FIG. 2, the hydrogen remaining amount detection device 14 includes a pair of support portions 15, a mixed molded body 16 and a plate-like electrode 17 corresponding to each support portion 15, and the corresponding support portions 15 and electrodes. 17 is connected by a mixed molded body 16. The pair of electrodes 17 are arranged to face the space 1 a of the hydrogen storage tank 1 at a predetermined interval, and are supported by the corresponding support 15 via the mixed molded body 16.
[0018]
The pair of support portions 15 are opposed to each other and protrude from the main body 15 a, and the main body 15 a is airtightly fixed to the opening of the hydrogen storage tank 1. The mixed molded body 16 is formed by mixing a hydrogen storage material 16a for detection made of a powdered alloy and a raw material of a rubber elastic body 16b having hydrogen permeability, and is an elastomer or natural material having hydrogen permeability. The hydrogen storage material 16a of the same type as the hydrogen storage material 2 is mixed and kneaded with rubber, and is molded and solidified into an arbitrary cross-sectional shape such as a rectangle or a circle with a predetermined thickness.
[0019]
As the rubber-like elastic body 16b, silicone rubber is suitable from the viewpoint of hydrogen permeability, but elastomer or natural rubber can be widely used. Each rubber-like elastic body 16b can be divided into a plurality of parts to increase the contact area with hydrogen gas. Further, as the rubber elastic body 16b made of a porous body having communication holes, it is possible to increase the contact area with hydrogen gas, and the hydrogen for detection made of a powdered alloy is used as the raw material of the rubber elastic body 16b. The storage material 16a is mixed and kneaded and then foamed, and the rubber elastic body 16b made of a porous body having as small communication holes as possible is molded and solidified to promote hydrogen permeation to the detection hydrogen storage material 16a. May be.
[0020]
Since the detection hydrogen storage material 16a made of an alloy has conductivity, an insulating coating 16c can be provided on the back surface of the electrode 17 as necessary in order to insulate the support portion 15. However, depending on the amount of the hydrogen storage substance 16a for detection contained in the rubber elastic body 16b, the rubber elastic body 16b itself is provided with a function of providing insulation between the electrode 17 and the support portion 15, or the main body 15a. Alternatively, if the support portion 15 is formed of an electrical insulator, the insulating coating 16c can be omitted. In addition, since the hydrogen remaining amount detection device 14 is provided in the hydrogen storage tank 1 in a non-contact state with the hydrogen storage material 2, in order to prevent adhesion of the hydrogen storage material 2, It is not essential to provide the insulating coating 16c.
[0021]
A display unit 20 is connected to each electrode 17 via a detection means 18 connected by a lead wire 19, and the capacitance between a pair of electrodes 17 functioning as a capacitor is electrically detected by a detection circuit 18. The amount is detected and converted into the remaining amount of hydrogen, and then displayed on the display unit 20 as the remaining amount of hydrogen occluded in the hydrogen storage material 2. The lead wire 19 passes through the main body 15a while maintaining airtightness.
[0022]
The mixed molded body 16 and the electrode 17 can be covered with a cover 13 having hydrogen permeability to prevent a short circuit due to the adhesion of the scattered hydrogen storage material 2 to the electrode 17. The cover 13 is provided not only on the lower surface portion of the support portion 15 but also on the side surface portion in a state of being installed on the pair of support portions 15, and the entire periphery of the electrode 17 can be covered with the cover 13, the main body 15 a and the support portion 15. it can.
[0023]
Next, the operation will be described. In a state where hydrogen gas is sufficiently stored in the hydrogen storage material 2 in the hydrogen storage tank 1, the hydrogen storage material 2 is heated to a predetermined temperature by the heating / cooling means 12 to release hydrogen from the hydrogen storage material 2. When hydrogen gas is supplied from the hydrogen release line 8 to the hydrogen utilization device 9 and hydrogen is consumed, the hydrogen storage amount of the hydrogen storage material 2 gradually decreases. At this time, since the inside of the hydrogen storage tank 1 is heated to a predetermined temperature as uniform as possible by the heating / cooling means 12, the hydrogen storage material 16a for detection of the hydrogen remaining amount detection device 14 located in the space 1a. Are under almost the same temperature environment. Accordingly, when the hydrogen storage amount of the hydrogen storage material 2 decreases, the hydrogen storage amount of the detection hydrogen storage material 16a of the remaining hydrogen detector 14 disposed in the space 1a of the hydrogen storage tank 1 also decreases.
[0024]
As a result, the volume of the hydrogen storage material for detection 16a is reduced, and the elastic rubber body 16b is elastically contracted so that it returns when solidified, so that the mixed molded body 16 contracts and the distance between the pair of electrodes 17 is increased. . Since the capacitance between the pair of electrodes 17 is inversely proportional to the distance between the electrodes 17, the capacitance between the electrodes 17 decreases as the distance between the pair of electrodes 17 increases. For example, when hydrogen is supplied to the fuel cell, the consumption is small, and the volume fluctuation of the hydrogen storage material 2 is made slow, so that the detection is performed via the rubber elastic body 16b having hydrogen permeability. The volume fluctuation of the hydrogen storage material 16a is also made to follow with little time delay.
[0025]
If the hydrogen storage material 2 in the tank 1 is supplied to the hydrogen storage material 2 in the tank 1 through the hydrogen inflow line 5 while cooling the hydrogen storage material 2 to a predetermined temperature by the heating / cooling means 12, the hydrogen storage material 2 The hydrogen storage amount gradually increases, and the hydrogen storage amount of the detection hydrogen storage material 16a of the hydrogen remaining amount detection device 14 disposed in the space 1a of the hydrogen storage tank 1 also increases. As a result, the volume of the hydrogen storage substance 16a for detection increases, and the rubber elastic body 16b expands elastically, so that the mixed molded body 16 expands and the distance between the pair of electrodes 17 decreases. The capacitance is increased by reducing the distance between the pair of electrodes 17. Thus, the remaining amount of hydrogen of the hydrogen storage material 2 can be detected from the capacitance value of each mixed molded body 16 in a predetermined volume change state. When the communication hole is provided in the rubber elastic body 16b, it is provided so as not to completely inhibit the elastic expansion (extension) of the rubber elastic body 16b accompanying the increase in the volume of the hydrogen storage material for detection 16a.
[0026]
By the way, the magnitude of the capacitance is determined by the surface area of the electrode 17, the atmospheric gas (the relative dielectric constant of the substance between the electrodes 17), and the distance (distance) between the electrodes 17. In this case, the hydrogen storage tank is always used. The surface area of the electrode 17 and the atmosphere gas (hydrogen) that are located in the space 1a and do not contact the hydrogen storage substance 2 accommodated in the hydrogen storage tank 1 are the same and do not change. As a result, the capacitance changes.
[0027]
The rubber-like elastic body 16b having excellent gas permeability functions as a rubber-like shape retaining material with respect to the granular material of the hydrogen storage substance for detection 16a. For this reason, the collapse phenomenon (pulverization phenomenon) caused by the expansion of the detection hydrogen storage material 16a due to the hydrogen storage apparently stops like a crack of the material 16a, and thus the detection hydrogen storage material 16a. As a result, the bulk density does not change substantially. Accordingly, volume expansion / contraction is repeatedly generated with high reproducibility, and a predetermined value of the electrostatic capacity can be detected accurately over a long period of time.
[0028]
Of course, at least a pair of the electrodes 17 of the hydrogen remaining amount detection device 14 is always in a non-contact state with the hydrogen storage material 2 so that the capacitance can be detected. The non-contact state is maintained even when hydrogen gas is occluded.
[0029]
The capacitance between the pair of electrodes 17 is detected and calculated by the detection means 18 and displayed on the display unit 20 as the remaining amount of hydrogen occluded in the hydrogen storage material 2. By knowing the amount of hydrogen stored in the hydrogen storage material 2 from the remaining amount of hydrogen displayed on the display unit 20, the hydrogen storage material 2 knows whether or not the time for hydrogen replenishment to the hydrogen storage material 2 has been reached. The hydrogen gas can be replenished before it is released.
[0030]
That is, the hydrogen remaining amount of the hydrogen storage substance 2 in the hydrogen storage tank 1 and the capacitance of the hydrogen remaining amount detecting device 14 have the relationship shown in FIG. 3, and the capacitance increases as the remaining amount of hydrogen decreases. Therefore, the remaining amount of hydrogen can be continuously detected from the capacitance value. Accordingly, it is timely known from the capacitance value that the remaining amount of hydrogen has decreased and the replenishment time has come, and the hydrogen storage material in the hydrogen storage tank 1 is supplied to the hydrogen gas in the hydrogen source 10 through the hydrogen inflow line 5. 2 can be replenished. Thereby, it is possible to avoid an unexpected situation in which the remaining amount of hydrogen becomes zero and hydrogen is not supplied to the hydrogen utilization device 9.
[0031]
By the way, in the first embodiment, the same kind of material (alloy) as the hydrogen storage material 2 is used as the hydrogen storage material 16a for detection, but the hydrogen storage material 16a for detection is a hydrogen storage material of the hydrogen storage material 2. A material that can occlude hydrogen in proportion to the amount can be employed, and a different kind of material (alloy) from the hydrogen storage material 2 can also be used. Further, the hydrogen remaining amount detection device 14 is disposed in the space 1a of the hydrogen storage tank 1, but may be disposed in a non-contact state with the hydrogen storage material 2, and an auxiliary tank is provided in the hydrogen storage tank 1 in communication. It is also possible to arrange the hydrogen remaining amount detection device 14 in the auxiliary tank included in the hydrogen storage tank 1 and detect the remaining amount of hydrogen in the hydrogen storage tank 1 in the same manner.
[0032]
【The invention's effect】
As understood from the above description, the method and apparatus for detecting the remaining amount of hydrogen according to the present invention can provide the following effects.
In the hydrogen storage tank that stores the hydrogen storage material therein, the remaining amount of hydrogen stored in the hydrogen storage material can be accurately detected in real time.
[0033]
Furthermore, the hydrogen remaining amount detecting device is disposed in a non-contact state with the hydrogen storage material, and the detection hydrogen storage material is held by the rubber elastic body, so that the change in bulk density is well prevented. Compared with a device in which the remaining amount detecting device is arranged in contact with the hydrogen storage material, all the problems associated with contacting are eliminated. That is, the remaining amount of hydrogen can be detected without being affected by the increase in volume caused by the pulverization of the hydrogen storage material accommodated in the hydrogen storage tank. As a result, it is possible to accurately detect the amount of occluded hydrogen and know the remaining amount for a long period of time without requiring an operation such as resetting to correct the detected capacitance value.
[0034]
In addition, since the hydrogen remaining amount detection device is disposed in a non-contact state with the hydrogen storage material, it can be disposed not only in the space of the hydrogen storage tank that stores the hydrogen storage material, but also communicated with the hydrogen storage tank. It is possible to detect the remaining amount of hydrogen in the hydrogen storage tank in the same manner by arranging it in the auxiliary tank provided in the state. In that case, it is not necessary to restrict the hydrogen storage material accommodated in the hydrogen storage tank to ensure a required space, and the degree of freedom in designing the remaining hydrogen amount detection device is improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a hydrogen remaining amount detection apparatus according to an embodiment of the present invention.
FIG. 2 is a view showing the main part of the hydrogen remaining amount detection device.
FIG. 3 is a diagram similarly showing the capacitance-water remaining amount characteristic.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1: Hydrogen storage tank, 1a: Space part, 2: Hydrogen storage substance, 9: Hydrogen utilization apparatus, 10: Hydrogen source, 13: Cover, 15: Support part, 16: Mixing molding, 16a: Hydrogen storage substance for detection 16b: rubbery elastic body, 17: electrode.

Claims

A method for detecting a remaining amount of hydrogen in a hydrogen storage material (2) contained in a hydrogen storage tank (1), comprising:
A mixed molded body in which a hydrogen storage material for detection (16a) and a rubber elastic body (16b) having hydrogen permeability are mixed with each of a pair of support portions (15) provided in the hydrogen storage tank (1) ( 16), the electrode (17) is supported, and the capacitance between the pair of electrodes (17) disposed opposite to the space (1a) of the hydrogen storage tank (1) is detected, and each mixed molded body ( 16) A method for detecting a remaining amount of hydrogen, comprising detecting a remaining amount of hydrogen from a capacitance value in a predetermined volume change state.

A hydrogen remaining amount detection device that is disposed inside a hydrogen storage tank (1) containing a hydrogen storage material (2) and detects the remaining amount of hydrogen in the hydrogen storage material (2),
The hydrogen remaining amount detection device includes a pair of support portions (15) provided in the hydrogen storage tank (1), and a pair of electrodes (17) disposed to face the space portion (1a) of the hydrogen storage tank (1). A mixed molded body (16) obtained by mixing a hydrogen storage material for detection (16a) and a rubber elastic body (16b) having hydrogen permeability, and a corresponding support portion (15) and electrode (17), Are connected by a mixed molded body (16),
A hydrogen remaining amount detecting device that detects a remaining amount of hydrogen from a capacitance value between a pair of electrodes (17) in a predetermined volume change state of each mixed molded body (16).

3. The hydrogen remaining amount detection device according to claim 2, wherein the hydrogen storage material for detection (16a) is the same type as the hydrogen storage material (2) stored in the hydrogen storage tank (1).

3. The hydrogen remaining amount detection device according to claim 2, wherein the hydrogen storage material for detection (16a) is of a different type from the hydrogen storage material (2) stored in the hydrogen storage tank (1).