JP4901049B2

JP4901049B2 - Thermoelectric conversion unit

Info

Publication number: JP4901049B2
Application number: JP2002338320A
Authority: JP
Inventors: 尊彦新藤; 秀泰安藤; 章子須山; 義康伊藤; 武久日野; 祐二郎中谷
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2002-11-21
Filing date: 2002-11-21
Publication date: 2012-03-21
Anticipated expiration: 2022-11-21
Also published as: JP2004172481A

Description

【０００１】
【発明の属する技術分野】
本発明は、熱から起電力を得る発電装置に係り、特にゼーベック効果を利用して熱から起電力を得る熱電変換素子を備えた熱電変換ユニットに関する。
【０００２】
【従来の技術】
熱電変換素子の利用形態は大別すると二つある。一つの利用形態は、熱電変換素子に流した直流電流により冷却または放熱を起こすペルチェ効果を利用した局部的な冷却システム用または加熱システム用への利用である。他方の利用形態は、熱電変換素子に温度差を与え、与えた温度差により起電力を発生するゼーベック効果による熱電変換を応用した発電装置としての利用である。
【０００３】
図１２に熱電変換素子を用いて構成される熱電変換ユニットを示す。
【０００４】
図１２に示される熱電変換ユニット１は、ｐ型の半導体２およびｎ型の半導体３と、ｐ型の半導体２の上下面の一方に接合されｐ型の半導体２から電気を取り出す電極部４ａと、ｎ型の半導体３の上下面の一方に接合され、ｎ型の半導体３から電気を取り出す電極部４ｂと、ｐ型の半導体２とｎ型の半導体３とにおいて電極部４ａおよび４ｂと対向する上下面の他方で接続される接続電極５と、電極部４ａおよび４ｂと接続電極５とを覆い保護する保護絶縁体６とを具備し、保護絶縁体６同士の隙間を樹脂７で塞いで形成される。
【０００５】
熱電変換ユニット１は、例えば、電気取り出し電極４ａおよび４ｂ側の面に低温熱源を、電極取り出し電極４ａおよび４ｂが接合される面と対向する面に高温熱源を接触させて熱エネルギを供給することで、低温熱源と高温熱源との温度差に応じた起電力、すなわち、電気エネルギが得られる。熱電変換により得られた起電力は電極部４ａおよび４ｂから取り出すことができる。
【０００６】
熱電変換ユニット１は、温度差を有する２つの熱源からの熱エネルギを電気エネルギに直接変換することが可能であり、環境への負荷が少ない低環境負荷型電源装置となり得る。このような熱電変換ユニット１は、例えば特開２００１−１０２６４４号公報に記載されている（特許文献１参照）。
【０００７】
また、熱電変換ユニット１以外に次世代の低環境負荷型電源装置として注目されているのは、太陽電池を用いた太陽光発電システムや水素を利用した燃料電池システムがある。
【０００８】
【特許文献１】
特開２００１−１０２６４４号公報
【０００９】
【発明が解決しようとする課題】
しかしながら、熱電変換ユニット１は、繰り返し使用および長期連続で使用した場合は、初回の発電時に比べて使用回数および使用日数を重ねる程、発電効率が低下するという問題があった。
【００１０】
また、その他の低環境負荷型電源装置である太陽光発電システムは、日照条件に左右されるので、太陽光発電システムの稼働率は一般に低く、発電量が変動する問題がある。太陽光発電システムは、安定した電力供給のために電源部を外部に設置する必要が生じる。一方、燃料電池については、発電の際に必要な燃料となる水素の価格が高いため発電コストが高くつくという問題があった。
【００１１】
本発明は、上述した事情を考慮してなされたもので、繰り返し使用および長期間使用した場合においても、初回の発電時の発電効率を維持可能な熱電変換ユニットを提供することを目的とする。
【００１２】
また、本発明の他の目的は、安定した発電により外部電源が無くても安定した電力供給が可能で、かつ、安価な発電コストでの電力供給を可能とする低環境負荷型電源装置としての熱電変換ユニットを提供するにある。
【００１３】
さらに、本発明の別の目的は、電力使用量を削減または外部からの電力供給無しでも周囲の温度差を用いて発電を行ないながら動作し得る熱電変換ユニットを提供するにある。
【００１４】
【課題を解決するための手段】
本発明に係る熱電変換ユニットは、上述した課題を解決するために、請求項１に記載したように、ｐ型の熱電変換素子およびｎ型の熱電変換素子とを少なくともそれぞれ１個は有する熱電変換機構と、前記熱電変換機構が有する熱電変換素子で発生した起電力を１つの電源装置として取り出すべく前記複数の熱電変換素子を電気的に接続する接続導体と、前記接続導体で接合された熱電変換機構の両端に位置する熱電変換素子から前記熱電変換機構で生じた起電力を取り出す電源端子を有する電極とを備え、前記接続導体および電極と前記熱電変換素子とを接合材料により接合して形成した熱電変換部と、湿度を極少に保持するよう前記熱電変換部を格納して密閉する密閉容器を具備し、前記熱電変換機構が有するｐ型の熱電変換素子およびｎ型の熱電変換素子は、ビスマス（Ｂｉ）とテルル（Ｔｅ）を主成分とし、前記ｐ型の熱電変換素子および前記ｎ型の熱電変換素子中の気孔率は、１０％以上６０％以下で、かつ、１０ｖｏｌ％以上５０ｖｏｌ％以下の無機材料を構造中に含有しており、前記無機材料は、石英、アルミナ、ムライト、チタニア、ジルコニアであることを特徴とする。尚、密閉容器内の湿度が極少とは、発電繰り返し回数８０回以上等の多数回の場合においても、初回発電量に対して９０％以上の発電量を維持可能な極僅かな湿度をいう。
【００１７】
さらに、本発明に係る熱電変換ユニットは、請求項２に記載したように、前記密閉容器中の雰囲気が、減圧雰囲気、窒素（Ｎ_２）雰囲気および不活性ガス雰囲気の少なくとも１つから選択されることを特徴とする。
【００１８】
さらにまた、本発明に係る熱電変換ユニットは、請求項３に記載したように、前記密閉容器中の圧力が、９ｋＰａ〜１１０ｋＰａであることを特徴とする。
【００２１】
さらに、本発明に係る熱電変換ユニットは、請求項４に記載したように、前記接合材料が、スズ（Ｓｎ）の融点より低い温度で溶融する低融点接合材料であることを特徴とする。
【００２２】
さらにまた、本発明に係る熱電変換ユニットは、請求項５に記載したように、前記接合材料として用いる接合材料が、スズ（Ｓｎ）の融点より低い温度で溶融する低融点接合材料であり、前記低融点接合材料は、スズ（Ｓｎ）・アンチモン（Ｓｂ）系材料、アルミニウム（Ａｌ）系材料、銅（Ｃｕ）・鉛（Ｐｂ）合金系材料、カドミウム（Ｃｄ）系材料、銅（Ｃｕ）・カドミウム（Ｃｄ）系材料、アルカリ硬化鉛系材料、亜鉛（Ｚｎ）系材料、焼結含油系材料から選択される１種類以上で構成されていることを特徴とする。
【００２３】
他方、本発明に係る熱電変換ユニットは、請求項６に記載したように、前記接合材料として用いる接合材料は、スズ（Ｓｎ）の融点より低い温度で溶融する低融点接合材料であり、前記低融点接合材料の厚さは２ｍｍ以下であることを特徴とする。
【００２７】
このような熱電変換ユニットは、繰り返し使用および長期間使用した場合においても、初回の発電時の発電効率を維持でき、安定した発電により外部電源が無くても安定した電力供給が可能、かつ、安価な発電コストでの電力供給を可能とする。
【００２９】
このような熱電変換ユニットは、電力を消費する電気機器の周辺の温度差により発電した電力を電気機器に供給し得るよう構成されているので、外部からの電力供給を削減または外部からの電力供給無しで電気機器を動作させることが可能となる。
【００３０】
【発明の実施の形態】
以下、本発明に係る熱電変換ユニットの実施形態を図面を参照して説明する。
【００３１】
[第１の実施形態]
図１に熱電変換ユニットの第１の実施形態の一実施例を示した熱電変換ユニット１０の構成概略図を示す。
【００３２】
図１に示される熱電変換ユニット１０は、例えば、図１２に示される熱電変換ユニット１と同様にｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２を少なくともそれぞれ１個ずつ有する熱電変換機構１３で熱電変換を行い、生じた起電力を取り出し得るよう構成される熱電変換手段１４と、この熱電変換手段１４を格納して密閉する密閉容器１５とを具備する。
【００３３】
図２に熱電変換手段１４の詳細を示す構造概要図を示す。
【００３４】
図２に示される熱電変換手段１４は、例えば、ｐ型の熱電変換素子１１を２個とｎ型の熱電変換素子１２を２個とを有する熱電変換手段１３と、個々の熱電変換素子を電気的に接続する接続導体１７と、電気的に接続されたｐ型の熱電変換素子１１とｎ型の熱電変換素子１２から起電力を取り出す取出口としての電源端子１８を有する電極１９と、接続導体１７および電極１９に直接触れないように周囲を覆い保護する表面保護絶縁体２０とを備える。
【００３５】
熱電変換手段１４が備えるｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２はＢｉ（ビスマス）−Ｔｅ（テルル）を主成分とする組成から構成される熱電変換素子である。そして、熱電変換手段１４が備える複数の熱電変換素子は、接続導体１７と接合材料２２によって接合されることで、電気的に直列に接続されて１つの電源供給装置として機能するよう構成される。
【００３６】
熱電変換手段１４が備える熱電変換素子の末端、例えば、図２に示される熱電変換手段１４で言えば、左端のｐ型の熱電変換素子１１ａと、右端のｎ型の熱電変換素子１２ｂとには、それぞれ、起電力を取り出す電源端子１８ａおよび１８ｂを有する電極１９ａおよび１９ｂが接合される。そして、熱電変換手段１４は、電極１９ａおよび１９ｂに設けられた電源端子１８ａおよび１８ｂから個々の熱電変換素子で生じた起電力を直列に取り出すことができる。また、熱電変換手段１４が備える接続導体１７および電極１９は、電源端子１８ａおよび１８ｂを除いた表面を直接手で触れることが無い様に絶縁し、かつ、外部衝撃から接続導体１７、電極１９および熱電変換機構１３を保護するために表面保護絶縁体２０で覆い、接合材料２２で接合される。
【００３７】
図１に示される熱電変換ユニット１０は、図２に示される熱電変換手段１４を密閉容器１５に格納し、電源端子１８ａおよび１８ｂを密閉容器１５外に出した状態で密閉する。そして、熱電変換手段１４を格納した密閉容器１５内部の湿度を極少に保持する。尚、密閉容器１５内の湿度を極少に保持するとは、発電を繰り返した回数（以下、繰り返し回数とする）が８０回程度の多数回の場合においても、初回発電量に対して、少なくとも９０％以上の発電量を維持可能な密閉容器１５内の湿度を保持することを言う。
【００３８】
また、密閉容器１５は、非導電性材料であり、例えば、エポキシ、アクリル、ポリテトラフルオロエチレン等の有機材料およびアルミナ等の無機材料で形成される。
【００３９】
図３に熱電変換ユニット１０による発電量と湿度が０，１，２，５，１０％の発電量の比較を示す。
【００４０】
図３に示される発電量は、熱電変換ユニット１０が具備する密閉容器１５内の湿度を０％に保持し、熱電変換ユニット１０に５０℃の温度差を設けて生じた１回目の発電量を１００として、密閉容器１５内の湿度および繰り返し回数を変化させた場合の発電量を１００に対する相対値で示している。
【００４１】
図３によれば、熱電変換ユニット１０が具備する密閉容器１５内の湿度を０％，１％に保持した場合に対して、湿度が１％より多い熱電変換ユニット１０は、繰り返した回数が多くなるほど発電量の低下が見られる。また、発電量の低下の傾向は、湿度が多い熱電変換ユニット１０ほど顕著な低下を示す。
【００４２】
繰り返し回数８０回で比較すれば、初回発電量の９０％以上の発電量が得られる湿度の範囲は０％〜２％であり、それ以上の湿度である５％および１０％の場合では、発電量が初回発電量の９０％未満となる。さらに、繰り返し回数１２０回で比較すれば、初回発電量の９０％以上の発電量が得られる湿度は０％，１％であり、それ以上の湿度である２％，５％，１０％の場合では、発電量が初回発電量の９０％未満となる。そして、密閉容器１５内の湿度が０％の場合の発電量は、初回発電量のほぼ１００％であり、密閉容器１５内の湿度が１％の場合の発電量は、初回発電量の約９６％と発電量の低下はあまり見られない。
【００４３】
従って、密閉容器１５内の湿度は、繰り返し回数８０回でも初回発電量の９０％以上の発電量が得られる０％〜２％の範囲内にするのが望ましい。また、密閉容器１５内の湿度のより望ましい範囲は、繰り返し回数１２０回でも初回発電量の９０％以上の発電量が得られる０％〜１％強であり、さらに望ましい範囲は繰り返し回数１２０回でも初回発電量の９５％以上の発電量が得られる０％〜１％以内である。
【００４４】
図４に図１に示される熱電変換機構１３が備える複数個の熱電変換素子、すなわち、図１に示されるｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２の個々の中に存在する気孔の割合（以下、気孔率とする）と熱電変換ユニット１０の発電量の関係を示す。
【００４５】
図４に示される発電量は、熱電変換機構１３が備えるｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２の気孔率が０％の場合に生じた発電量を１００として、ｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２の気孔率のみを変化させた場合の発電量を１００に対する相対値で示している。
【００４６】
図４によれば、熱電変換素子中の気孔率が大きくなるほど発電量は大きくなる傾向を示す。しかし、熱電変換素子中の気孔率が多くなるほど、加工性はより悪くなり熱電変換素子製造時にチッピング等が起こりやすくなる。つまり、熱電変換素子中の気孔率が多くなるほど、歩留まりが低下する。従って、熱電変換素子中の気孔率は、加工性の悪化が歩留まりの著しい低下を招かない範囲、かつ、気孔率０％時の発電量に対して発電量増加が５％以上認められる範囲である１０％以上６０％以下の範囲が望ましい。また、熱電変換素子中の気孔率のより望ましい範囲は、１０％以上５０％未満であり、さらに望ましくは、１０％以上４５％以下である。
【００４７】
図５に図１に示される熱電変換機構１３が備えるｐ型の熱電変換素子１１とｎ型の熱電変換素子１２の構造中に無機材料であるアルミナ、ムライト、チタニア、ジルコニアを含有させた熱電変換素子を用いた熱電変換ユニット１０と、例えば、図１２に示される熱電変換ユニット１等の従来の熱電変換ユニット（以下、従来品とする）との比較を示す。
【００４８】
図５に示される発電量は、従来品における発電量を１００として、図１に示されるｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２の構造中に無機材料であるアルミナ、ムライト、チタニア、ジルコニアを、例えば、２０％ｖｏｌ等のある一定割合で含有させた場合における発電量を１００に対する相対値で示している。
【００４９】
図５によれば、ｐ型の熱電変換素子１１とｎ型の熱電変換素子１２の構造中に無機材料である、アルミナ、ムライト、チタニア、ジルコニアを含有させた場合は、アルミナで約１０７％、ムライトで約１２２％、チタニアで約１１２％、ジルコニアで約１１６％と、何れも従来品の発電量と比較して約７％〜２２％発電量が高くなる。
【００５０】
尚、図５には示されていないが、無機材料に石英を使用しても図５に示される無機材料と同様に発電量の増加が認められる。
【００５１】
図６に図１に示される熱電変換機構１３が備えるｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２の熱電変換素子の構造中に、例えば、アルミナ等の無機材料を含有させて無機材料の含有量（ｖｏｌ％）を変化させた場合における無機材料の含有量と発電量の関係を示す。
【００５２】
図６に示される発電量は、熱電変換機構１３が備えるｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２の構造中にアルミナの含有量が０ｖｏｌ％、すなわち、ｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２の構造中にアルミナを含有しない場合に生じた発電量を１００として、ｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２の構造中に含有されるアルミナ含有量のみを変化させた場合の発電量を１００に対する相対値で示している。
【００５３】
図６によれば、アルミナの含有量が大きくなるほど発電量は大きくなる傾向を示す。しかし、アルミナの含有量が多くなると加工性が悪くなり、チッピング等が発生しやすくなるため歩留まりが低下する。従って、熱電変換素子中のアルミナの含有量は、加工性の悪化が歩留まりの著しい低下を招かない範囲、かつ、アルミナ含有量０ｖｏｌ％時の発電量に対して発電量増加が５％以上認められる１０ｖｏｌ％以上５０ｖｏｌ％以下が望ましい。また、アルミナ含有量のより望ましい範囲は１０ｖｏｌ％以上４５ｖｏｌ％以下であり、さらに望ましい範囲は１０ｖｏｌ％以上４０％以下である。
【００５４】
図６に示される傾向は、石英、ムライト、チタニア、ジルコニア等、アルミナ以外の無機材料を含有させた熱電変換素子を用いて構成される熱電変換ユニット１０でも同様の傾向を示す。
【００５５】
図７に熱電変換ユニット１０が具備する密閉容器１５中の雰囲気が、大気雰囲気、減圧雰囲気、窒素（以下、Ｎ_２とする）雰囲気、不活性ガス雰囲気の場合の発電量の比較を示す。
【００５６】
図７に示される発電量は、図１に示される密閉容器１５内の雰囲気を大気雰囲気、すなわち、大気中と同じ気圧、湿度にして、繰り返し回数１００回の場合に生じた発電量を１００として、密閉容器１５内の雰囲気のみを、減圧雰囲気と、Ｎ_２雰囲気と、不活性ガス雰囲気とに変化させた場合の発電量を１００に対する相対値で示している。
【００５７】
図７によれば、大気雰囲気に対して、減圧雰囲気、Ｎ_２雰囲気、不活性ガス雰囲気の場合は、発電回数を１００回繰り返しても発電量の低下がほとんど見られないため、いずれも発電量比が１００％以上であり、約１１０％〜１２０％となっている。従って、密閉容器１５内は、減圧雰囲気、Ｎ_２雰囲気、不活性ガス雰囲気の何れかから選択される雰囲気が望ましい。
【００５８】
また、減圧雰囲気における密閉容器中の圧力は、９ｋＰａ〜１００ｋＰａが望ましい。そして、減圧雰囲気における密閉容器中の圧力のより望ましい範囲は、９ｋＰａ〜８０ｋＰａであり、さらに望ましくは、９ｋＰａ〜６０ｋＰａである。一方、Ｎ_２雰囲気、不活性ガス雰囲気における密閉容器中の圧力は、９ｋＰａ〜１１０ｋＰａが望ましい。そして、Ｎ_２雰囲気、不活性ガス雰囲気における密閉容器中の圧力のより望ましい範囲は、３０ｋＰａ〜１１０ｋＰａであり、さらに望ましくは、５０ｋＰａ〜１１０ｋＰａである。
【００５９】
図８に熱電ユニット１０が具備する熱電変換手段１４において、ｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２と接続導体１７および電極１９を接合する接合材料２２に従来と同様の接着剤を使用して接合した場合（以下、従来接合方法とする）と、接合材料２２に例えば、スズ・アンチモン系材料である低融点接合材料をハンダによって接合した場合の発電量を示す。尚、低融点接合材料とは、スズ単体が固体の状態で溶融する材料、すなわち、スズの融点（２３２℃）よりも融点が低い材料を言う。
【００６０】
図８に示される発電量は、接合材料２２に低融点接合材料を使用した場合の発電量を従来接合方法での発電量を１００とした相対値で示している。図８によれば、接合材料２２に低融点材料を使用した場合の発電量比は約１７０％であり、従来接合方法により接合した熱電変換ユニット（図８においては従来品と記す）の約１．７倍になることがわかる。従って、図１に示される熱電変換ユニット１０に用いられる接合材料２２は、従来使用される接着剤よりも、低融点接合材料を使用する方が発電量増加の観点から見て望ましい。
【００６１】
また、接合材料２２として用いられる低融点接合材料は、スズ（Ｓｎ）・アンチモン（Ｓｂ）系材料の他にアルミニウム（Ａｌ）系材料、銅（Ｃｕ）・鉛（Ｐｂ）合金系材料、カドミウム（Ｃｄ）系材料、銅（Ｃｕ）・カドミウム（Ｃｄ）系材料、アルカリ硬化鉛系材料、亜鉛（Ｚｎ）系材料、焼結含油系材料から選択される少なくとも１種類を有して構成されていれば同様の効果が得られる。
【００６２】
一方、図８に示される特性を導出する際に、熱電変換ユニット１０の接合材料２２としての低融点接合材料をハンダで接合した熱電変換ユニット１０を使用したが、接合材料２２の接合手法は、ハンダ以外にも、肉盛り、溶接、ロウ付けで接合しても同様の効果が得られる。さらに、低融点接合材料の厚さは、図８に示される発電量増大の傾向に大きな影響を及ぼさないが、経済性の観点からすれば、２ｍｍ以下であることが望ましい。
【００６３】
本実施形態の熱電ユニットによれば、熱電変換ユニット１０が具備する密閉容器１５内の湿度を０％〜１％に保持することで、繰り返し回数１００回以上でも初回発電量の９５％以上の発電量を維持することが可能である。
【００６４】
また、熱電変換ユニット１０が具備する熱電変換手段１４に用いられるｐ型の熱電変換素子１１およびｎ型の熱電変換素子１２に含有される気孔の割合や無機材料の種類および割合や密閉容器１５内の雰囲気を適切に選択することで発電量を増大させることができる。さらに、熱電変換手段１４が備える接合導体１７および電極１９と熱電変換機構１３および保護絶縁体２０とを接合する接合材料２２を低融点接合材料とすることで発電量を増大させることができる。
【００６５】
尚、本実施形態では、密閉容器１５内に保護絶縁体２０で覆われた熱電変換手段１４を格納しているが、熱電変換手段１４が保護絶縁体２０を備えていない状態で熱電変換手段１４を密閉容器１５内に格納していても良い。また、密閉容器１５に用いられる非導電性材料は、金属表面に絶縁コーティング等の非導電性処理を施した金属材料でも構わない。
【００６６】
[第２の実施形態]
図９〜図１１に第２の実施形態を示す熱電変換ユニットの一例を示す。
【００６７】
図９〜図１１に示される熱電変換ユニット１０Ａ〜１０Ｃは、熱供給源２５と、図１に示される熱電変換ユニット１０と同様の機構を備えた電力供給部２６とを備えた熱電変換ユニットであり、熱電変換ユニットの第１実施形態として図１に示される熱電変換ユニット１０とは熱電変換を行う熱供給源２５を備える点が異なっている。熱電変換ユニット１０Ａは、熱供給源２５を備える点以外は本質的には異ならないので、第１の実施形態を示す熱電変換ユニット１０と本質的に異ならない個所には同じ符号を付して説明を省略する。
【００６８】
図９に熱供給源２５に水道配管を用いた熱電変換ユニット１０Ａの一例を示す。
【００６９】
図９に示される熱電変換ユニット１０Ａには、熱供給源２５として例えば、電源供給の必要な水道メータ等の電力を消費して動作する装置（以下、電気機器とする）２９を有する水道配管を用い、電力供給部２６と、電力供給部２６から電気機器２９へ電力を供給する電力供給媒体３０とを具備する。
【００７０】
熱電変換ユニット１０Ａは、電気機器２９として水道メータを有する水道配管周囲の温度差を熱供給源２５として熱エネルギを取り出す。そして、熱供給源２５からの熱エネルギを利用して、電力供給部２６で熱電変換を行うことで発電を行う熱供給源２５と電力供給部２６とが一体となった熱電変換ユニットである。図９に示される熱電変換ユニット１０Ａは、水道配管を通して得られる水温、地温、大気温からの温度差を熱供給源２５として利用して、取り出した熱エネルギを図１に示される熱電変換ユニット１０と同様の機構を備える電力供給部２６で熱電変換を行う。熱電変換ユニット１０Ａに備えられる電力供給部２６が熱電変換することで生じた起電力は、電気機器２９としての水道メータの電源として利用可能に構成される。
【００７１】
また、第２の実施形態におけるその他の実施例としての熱電変換ユニット１０Ｂの一例を図１０に示す。
【００７２】
図１０に示される熱電変換ユニット１０Ｂは、電気機器２９としてガス流量計を有するガス配管と、電力供給部２６と、電力供給媒体３０とを具備する。熱電変換ユニット１０Ｂは、ガス配管を通して得られるガス温、大気温からの温度差を熱供給源２５として電力供給部２６で熱電変換を行うことで発電を行う。図１０に示される熱電変換ユニット１０Ｂが具備する電力供給部２６で発電された電力は、電力供給媒体３０により電気機器２９としてのガス流量計に供給され、ガス流量計が駆動する。
【００７３】
さらに、第２の実施形態におけるその他の実施例としての熱電変換ユニット１０Ｃの一例を図１１に示す。
【００７４】
図１１に示される熱電変換ユニット１０Ｃは、図９に示される熱電変換ユニット１０Ａと、電力供給を制御可能な電力供給制御手段を備えたバッテリ３５とを具備している。
【００７５】
熱電変換ユニット１０Ｃは、熱電変換して得た起電力を一度バッテリ３５に蓄電して、バッテリ３５を介して電気機器２９を稼動させる。バッテリ３５を具備する熱電変換ユニット１０Ｃは、熱供給源２５付近の温度が変化して発電量が変動して不安定であっても、電気機器２９としての水道メータには一定の電力量を供給することができる。また、バッテリ３５が電力供給制御手段を備えることで、発電された電気を必要な時に電気機器２９としての水道メータに供給することができる。
【００７６】
本実施形態の熱電ユニットによれば、熱供給源２５と熱電変換を行う電力供給部２６とを具備する熱電ユニットであるため、例えば、水道メータを有する水道配管等の電気機器２９を有する装置を熱供給源２５とした熱電変換ユニット１０Ａの場合は、水道配管の周囲の温度差を熱エネルギとして取り出して、電力供給部２６で熱電変換を行い発電した電力で電気機器２９を動作させることができので、電気機器２９を動作させるための外部電源が不要となる。
【００７７】
また、他の実施例として、電力供給制御手段を備えるバッテリ３５を具備する熱電変換ユニット１０Ｃは、熱供給源２５付近の温度が変化して発電量が不安定であっても、一定の電力量を供給することができる。さらに、電力供給制御手段が電力供給を制御することで、熱電変換ユニット１０Ｃで発電した電力を通常使用する電気機器２９としての水道メータ以外の電気機器２９に供給することも可能となる。
【００７８】
尚、熱電変換ユニット１０Ｃが具備するバッテリ３５は、電力供給制御手段を備えているとしたが、電力供給制御手段を備えていなくても電気機器２９に一定の電力量を供給することは可能である。
【００７９】
【発明の効果】
本発明に係る熱電変換ユニットによれば、繰り返し使用および長期間使用した場合においても、ほとんど発電量が低下することなく、初回の発電時の発電量を維持することができる。
【００８０】
また、熱電変換ユニットは、熱エネルギを電気エネルギに直接変換する低環境負荷型電源装置であり、熱電変換ユニットの周囲の温度差を利用して安定した発電が可能である。そして、利用する熱エネルギは自然環境中に生じる温度差を利用できるので発電コストを抑えた電力供給が可能となる。
【００８１】
さらに、熱電変換ユニットは、熱電変換ユニットに具備される熱電変換手段が周囲の温度差を利用して発電を行なうため、温度差を有し、電力を消費して動作する何らかの電気機器と、熱電変換ユニットとを備えた電気機器一体型熱電変換ユニットを形成すれば、熱電変換ユニット外部からの電力供給がほとんどなし、または電力供給が全く無しでも電気機器一体型熱電変換ユニットが備える電気機器を動作可能に構成できる。
【図面の簡単な説明】
【図１】本発明に係る熱電変換ユニットの構成概要図。
【図２】本発明に係る熱電変換ユニットが具備する熱電変換手段の構成概要図。
【図３】本発明に係る熱電変換ユニットが備える密閉容器内の湿度を０％〜１０％の範囲で変化させて熱電変換を行った場合における熱電変換ユニットでの発電回数と発電量比との関係を示す相関図。
【図４】本発明に係る熱電変換ユニットが備える熱電素子中の気孔の割合を変化させて熱電変換を行った場合における熱電素子中の気孔の割合と発電量比との関係を示す相関図。
【図５】本発明に係る熱電変換ユニットが備える熱電変換素子に含有される無機材料の種類を変化させて熱電変換した場合における無機材料の種類と発電量比との関係を説明する説明図。
【図６】本発明に係る熱電変換ユニットが備える熱電素子に含有されるアルミナ（無機材料）の含有量（ｖｏｌ％）を変化させて熱電変換した場合における無機材料の含有量と発電量比との関係を示す相関図。
【図７】本発明に係る熱電変換ユニットで熱電変換を１００回行った場合における熱電変換ユニットが備える密閉容器内の雰囲気と発電量比との関係を説明した説明図。
【図８】本発明に係る熱電変換ユニットで熱電変換を行った場合において熱電変換ユニットが備える熱源部と電極、電極と絶縁体との接合面に低融点合金材料を使用した場合と接着剤を使用した場合とにおける発電量比の関係を説明した説明図。
【図９】本発明に係る熱電変換ユニットを水道配管に取り付け、水道メータへの電源供給源として適用した熱電変換ユニットの一実施例を示す装置構成図。
【図１０】本発明に係る熱電変換ユニットをガス配管に取り付け、ガスメータへの電源供給源として適用した熱電変換ユニットの一実施例を示す装置構成図。
【図１１】本発明に係る熱電変換ユニットを水道配管に取り付け、発生した電気をバッテリに蓄電し、このバッテリを水道メータへの電源供給源として適用した熱電変換ユニットの一実施例を示す装置構成図。
【図１２】従来の熱電変換ユニットの概略図。
【符号の説明】
１０…熱電変換ユニット、１１…ｐ型の熱電変換素子、１２…ｎ型の熱電変換素子、１３…熱電変換機構、１４…熱電変換手段、１５…密閉容器、１７…接続導体、１８ａ，１８ｂ…電源端子、１９ａ，１９ｂ…電極、２０…表面保護絶縁体、２５…熱供給源、２６…電力供給部、２９…電気機器、３０，３０ａ，３０ｂ…電力供給媒体、３５…バッテリ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power generation apparatus that obtains electromotive force from heat, and more particularly, to a thermoelectric conversion unit that includes a thermoelectric conversion element that obtains electromotive force from heat using the Seebeck effect.
[0002]
[Prior art]
There are two types of usage of thermoelectric conversion elements. One use form is a use for a local cooling system or a heating system using a Peltier effect in which cooling or heat dissipation is caused by direct current flowing in a thermoelectric conversion element. The other utilization form is utilization as a power generation device applying thermoelectric conversion by the Seebeck effect that gives a thermoelectric conversion element a temperature difference and generates an electromotive force by the given temperature difference.
[0003]
FIG. 12 shows a thermoelectric conversion unit configured using thermoelectric conversion elements.
[0004]
A thermoelectric conversion unit 1 shown in FIG. 12 includes a p-type semiconductor 2 and an n-type semiconductor 3, and an electrode portion 4 a that is joined to one of the upper and lower surfaces of the p-type semiconductor 2 and extracts electricity from the p-type semiconductor 2. The electrode portion 4b is joined to one of the upper and lower surfaces of the n-type semiconductor 3 and takes out electricity from the n-type semiconductor 3, and the electrode portions 4a and 4b are opposed to each other in the p-type semiconductor 2 and the n-type semiconductor 3. It includes a connection electrode 5 connected on the other of the upper and lower surfaces, a protective insulator 6 that covers and protects the electrode portions 4a and 4b and the connection electrode 5, and is formed by closing the gap between the protective insulators 6 with a resin 7. Is done.
[0005]
For example, the thermoelectric conversion unit 1 supplies thermal energy by bringing a low-temperature heat source into contact with the surface on the electric extraction electrodes 4a and 4b side and a high-temperature heat source in contact with the surface facing the surface where the electrode extraction electrodes 4a and 4b are joined. Thus, an electromotive force according to the temperature difference between the low-temperature heat source and the high-temperature heat source, that is, electric energy can be obtained. The electromotive force obtained by thermoelectric conversion can be taken out from the electrode parts 4a and 4b.
[0006]
The thermoelectric conversion unit 1 can directly convert heat energy from two heat sources having a temperature difference into electric energy, and can be a low environmental load type power supply device with a low environmental load. Such a thermoelectric conversion unit 1 is described in, for example, Japanese Patent Application Laid-Open No. 2001-102644 (see Patent Document 1).
[0007]
In addition to the thermoelectric conversion unit 1, as a next-generation low environmental load type power supply device, there are a solar power generation system using a solar cell and a fuel cell system using hydrogen.
[0008]
[Patent Document 1]
JP 2001-102644 A
[0009]
[Problems to be solved by the invention]
However, when the thermoelectric conversion unit 1 is used repeatedly and continuously for a long period of time, there is a problem that the power generation efficiency decreases as the number of times of use and the number of days of use are increased as compared with the first power generation.
[0010]
Moreover, since the photovoltaic power generation system which is another low environmental load type power supply device is influenced by sunshine conditions, the operation rate of the photovoltaic power generation system is generally low, and there is a problem that the amount of power generation fluctuates. In the photovoltaic power generation system, it is necessary to install a power supply unit outside for stable power supply. On the other hand, the fuel cell has a problem that the cost of power generation is high due to the high price of hydrogen, which is a fuel necessary for power generation.
[0011]
The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a thermoelectric conversion unit capable of maintaining the power generation efficiency at the time of the first power generation even when repeatedly used and used for a long time.
[0012]
Another object of the present invention is as a low environmental load type power supply device that can stably supply power even if there is no external power supply by stable power generation, and can supply power at a low power generation cost. To provide a thermoelectric conversion unit.
[0013]
Furthermore, another object of the present invention is to provide a thermoelectric conversion unit that can operate while performing power generation using a temperature difference in the surroundings without reducing power consumption or without external power supply.
[0014]
[Means for Solving the Problems]
In order to solve the above-described problem, the thermoelectric conversion unit according to the present invention has at least one p-type thermoelectric conversion element and n-type thermoelectric conversion element as described in claim 1. Mechanism, a connection conductor for electrically connecting the plurality of thermoelectric conversion elements so as to take out an electromotive force generated in the thermoelectric conversion element of the thermoelectric conversion mechanism as one power supply device, and thermoelectric conversion joined by the connection conductor An electrode having a power supply terminal for extracting an electromotive force generated in the thermoelectric conversion mechanism from thermoelectric conversion elements located at both ends of the mechanism, and formed by bonding the connection conductor and the electrode and the thermoelectric conversion element with a bonding material A thermoelectric conversion unit, and a p-type thermoelectric conversion element included in the thermoelectric conversion mechanism, including a thermoelectric conversion unit and a sealed container that stores and seals the thermoelectric conversion unit so as to keep humidity at a minimum. Type thermoelectric conversion element Is mainly composed of bismuth (Bi) and tellurium (Te), p-type thermoelectric conversion element and Above The porosity of the n-type thermoelectric conversion element is 10% or more and 60% or less, and contains 10 vol% or more and 50 vol% or less of an inorganic material in the structure, and the inorganic material includes quartz, alumina, mullite. , Titania and zirconia. The extremely low humidity in the sealed container means a very low humidity that can maintain a power generation amount of 90% or more with respect to the initial power generation amount even in the case of a large number of power generation repetitions such as 80 times or more.
[0017]
Further, the thermoelectric conversion unit according to the present invention is as follows. 2 As described above, the atmosphere in the sealed container is a reduced-pressure atmosphere, nitrogen (N ₂ ) It is selected from at least one of an atmosphere and an inert gas atmosphere.
[0018]
Furthermore, the thermoelectric conversion unit according to the present invention is a claim. 3 As described above, the pressure in the closed container is 9 kPa to 110 kPa.
[0021]
Further, the thermoelectric conversion unit according to the present invention is as follows. 4 As described above, the bonding material is a low melting point bonding material that melts at a temperature lower than the melting point of tin (Sn).
[0022]
Furthermore, the thermoelectric conversion unit according to the present invention is a claim. 5 As described above, the bonding material used as the bonding material is a low melting point bonding material that melts at a temperature lower than the melting point of tin (Sn), and the low melting point bonding material is tin (Sn) / antimony (Sb). Materials, aluminum (Al) materials, copper (Cu) / lead (Pb) alloy materials, cadmium (Cd) materials, copper (Cu) / cadmium (Cd) materials, alkali-cured lead materials, zinc ( It is characterized by being composed of one or more selected from Zn) -based materials and sintered oil-impregnated materials.
[0023]
On the other hand, the thermoelectric conversion unit according to the present invention is a claim. 6 As described above, the bonding material used as the bonding material is a low melting point bonding material that melts at a temperature lower than the melting point of tin (Sn), and the thickness of the low melting point bonding material is 2 mm or less. And
[0027]
Such a thermoelectric conversion unit can maintain the power generation efficiency at the first power generation even when it is used repeatedly and for a long period of time. Stable power generation enables stable power supply without an external power source and is inexpensive. This makes it possible to supply power at a reasonable power generation cost.
[0029]
Such a thermoelectric conversion unit is configured to be able to supply electric power generated by a temperature difference around the electric device that consumes electric power to the electric device, thereby reducing external power supply or supplying power from the outside It is possible to operate an electric device without using it.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a thermoelectric conversion unit according to the present invention will be described with reference to the drawings.
[0031]
[First embodiment]
FIG. 1 is a schematic configuration diagram of a thermoelectric conversion unit 10 showing an example of the first embodiment of the thermoelectric conversion unit.
[0032]
The thermoelectric conversion unit 10 shown in FIG. 1 is, for example, a thermoelectric conversion mechanism having at least one p-type thermoelectric conversion element 11 and one n-type thermoelectric conversion element 12 as in the thermoelectric conversion unit 1 shown in FIG. 13 includes a thermoelectric conversion means 14 configured to perform thermoelectric conversion and take out the generated electromotive force, and a sealed container 15 for storing and sealing the thermoelectric conversion means 14.
[0033]
FIG. 2 is a structural schematic diagram showing details of the thermoelectric conversion means 14.
[0034]
The thermoelectric conversion means 14 shown in FIG. 2 includes, for example, thermoelectric conversion means 13 having two p-type thermoelectric conversion elements 11 and two n-type thermoelectric conversion elements 12, and each thermoelectric conversion element. Connecting conductor 17 connected electrically, p-type thermoelectric conversion element 11 and electrode 19 having power supply terminal 18 as an outlet for taking out electromotive force from n-type thermoelectric conversion element 12, and connection conductor 17 and a surface protection insulator 20 that covers and protects the surroundings so as not to directly touch the electrode 17 and the electrode 19.
[0035]
The p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 included in the thermoelectric conversion means 14 are thermoelectric conversion elements having a composition mainly composed of Bi (bismuth) -Te (tellurium). And the several thermoelectric conversion element with which the thermoelectric conversion means 14 is equipped is joined by the connection conductor 17 and the joining material 22, and is electrically connected in series and is comprised so that it may function as one power supply device.
[0036]
For example, in the case of the thermoelectric conversion device 14 shown in FIG. 2, the leftmost p-type thermoelectric conversion device 11 a and the rightmost n-type thermoelectric conversion device 12 b include: Electrodes 19a and 19b having power supply terminals 18a and 18b for taking out electromotive force are joined. And the thermoelectric conversion means 14 can take out the electromotive force which arose in each thermoelectric conversion element in series from the power supply terminals 18a and 18b provided in the electrodes 19a and 19b. Further, the connection conductor 17 and the electrode 19 included in the thermoelectric conversion means 14 are insulated so that the surfaces except for the power supply terminals 18a and 18b are not directly touched by the hand, and the connection conductor 17, the electrode 19 and the In order to protect the thermoelectric conversion mechanism 13, it is covered with a surface protection insulator 20 and bonded with a bonding material 22.
[0037]
The thermoelectric conversion unit 10 shown in FIG. 1 stores the thermoelectric conversion means 14 shown in FIG. 2 in a sealed container 15 and seals the power supply terminals 18a and 18b in a state where the power terminals 18a and 18b are out of the sealed container 15. And the humidity inside the airtight container 15 storing the thermoelectric conversion means 14 is kept to a minimum. Note that keeping the humidity in the sealed container 15 to a minimum means that at least 90% of the initial power generation amount even when the number of times of power generation is repeated (hereinafter referred to as the number of repetitions) is about 80 times. It means that the humidity in the sealed container 15 capable of maintaining the above power generation amount is maintained.
[0038]
Moreover, the airtight container 15 is a nonelectroconductive material, for example, is formed with inorganic materials, such as organic materials, such as an epoxy, an acryl, a polytetrafluoroethylene, and alumina.
[0039]
FIG. 3 shows a comparison between the amount of power generated by the thermoelectric conversion unit 10 and the amount of power generated when the humidity is 0, 1, 2, 5, and 10%.
[0040]
The power generation amount shown in FIG. 3 is the first power generation amount generated by keeping the humidity in the sealed container 15 included in the thermoelectric conversion unit 10 at 0% and providing the thermoelectric conversion unit 10 with a temperature difference of 50 ° C. As 100, the power generation amount when the humidity in the sealed container 15 and the number of repetitions are changed is shown as a relative value with respect to 100.
[0041]
According to FIG. 3, the thermoelectric conversion unit 10 having a humidity higher than 1% has a large number of repetitions compared to the case where the humidity in the sealed container 15 included in the thermoelectric conversion unit 10 is maintained at 0% and 1%. I see a decrease in power generation. Moreover, the tendency of the power generation amount to decrease is more marked as the thermoelectric conversion unit 10 has a higher humidity.
[0042]
If the number of repetitions is compared at 80 times, the range of humidity at which 90% or more of the initial power generation is obtained is 0% to 2%, and in the case of 5% and 10% above that, power generation The amount is less than 90% of the initial power generation. Furthermore, if the number of repetitions is 120, the humidity at which 90% or more of the initial power generation is obtained is 0% or 1%, and the humidity is 2%, 5% or 10%, which is higher than that. Then, the power generation amount is less than 90% of the initial power generation amount. The power generation amount when the humidity inside the sealed container 15 is 0% is almost 100% of the initial power generation amount, and the power generation amount when the humidity inside the sealed container 15 is 1% is about 96 of the initial power generation amount. % And the decrease in power generation is not seen so much.
[0043]
Therefore, it is desirable that the humidity in the sealed container 15 be within a range of 0% to 2% where a power generation amount of 90% or more of the initial power generation amount can be obtained even with 80 repetitions. Further, the more desirable range of the humidity in the sealed container 15 is 0% to 1%, which can obtain a power generation amount of 90% or more of the initial power generation amount even at 120 repetitions, and the more desirable range is even at 120 repetitions. It is within 0% to 1% at which a power generation amount of 95% or more of the initial power generation amount is obtained.
[0044]
4 exists in each of a plurality of thermoelectric conversion elements provided in the thermoelectric conversion mechanism 13 shown in FIG. 1, that is, the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 shown in FIG. The relationship between the ratio of pores (hereinafter referred to as porosity) and the amount of power generated by the thermoelectric conversion unit 10 is shown.
[0045]
The power generation amount shown in FIG. 4 is a p-type power generation amount that is 100 when the porosity of the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 included in the thermoelectric conversion mechanism 13 is 0%. The power generation amount when only the porosity of the thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 is changed is shown as a relative value with respect to 100.
[0046]
According to FIG. 4, the power generation amount tends to increase as the porosity in the thermoelectric conversion element increases. However, as the porosity in the thermoelectric conversion element increases, the workability becomes worse and chipping or the like is likely to occur during the manufacture of the thermoelectric conversion element. That is, the yield decreases as the porosity in the thermoelectric conversion element increases. Therefore, the porosity in the thermoelectric conversion element is within a range where deterioration in workability does not cause a significant decrease in yield, and within a range where an increase in power generation amount is recognized by 5% or more with respect to the power generation amount when the porosity is 0%. A range of 10% to 60% is desirable. Moreover, the more desirable range of the porosity in the thermoelectric conversion element is 10% or more and less than 50%, and more desirably 10% or more and 45% or less.
[0047]
Thermoelectric conversion in which alumina, mullite, titania and zirconia, which are inorganic materials, are contained in the structure of the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 provided in the thermoelectric conversion mechanism 13 shown in FIG. A comparison is made between a thermoelectric conversion unit 10 using elements and a conventional thermoelectric conversion unit (hereinafter referred to as a conventional product) such as the thermoelectric conversion unit 1 shown in FIG.
[0048]
The power generation amount shown in FIG. 5 is that the power generation amount in the conventional product is 100, and the structures of the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 shown in FIG. The power generation amount when titania and zirconia are contained at a certain ratio such as 20% vol is shown as a relative value with respect to 100.
[0049]
According to FIG. 5, when alumina, mullite, titania, and zirconia, which are inorganic materials, are included in the structures of the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12, about 107% with alumina, About 122% for mullite, about 112% for titania, and about 116% for zirconia, the power generation amount is about 7% to 22% higher than that of the conventional product.
[0050]
Although not shown in FIG. 5, even if quartz is used as the inorganic material, an increase in the amount of power generation is recognized as in the inorganic material shown in FIG.
[0051]
In the structure of the thermoelectric conversion elements of the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 provided in the thermoelectric conversion mechanism 13 shown in FIG. The relationship between the content of inorganic material and the amount of power generation when the content (vol%) of the material is changed is shown.
[0052]
The power generation amount shown in FIG. 6 is that the content of alumina is 0 vol% in the structure of the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 provided in the thermoelectric conversion mechanism 13, that is, the p-type thermoelectric conversion element. Alumina contained in the structure of the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 with the amount of power generated when no alumina is contained in the structure of the 11-type and n-type thermoelectric conversion elements 12 being 100 The power generation amount when only the content is changed is shown as a relative value with respect to 100.
[0053]
According to FIG. 6, the power generation amount tends to increase as the alumina content increases. However, when the content of alumina is increased, the workability is deteriorated and chipping or the like is likely to occur, resulting in a decrease in yield. Therefore, the content of alumina in the thermoelectric conversion element is within a range where deterioration in workability does not cause a significant decrease in yield, and an increase in power generation amount of 5% or more with respect to the power generation amount when the alumina content is 0 vol% is recognized. 10 vol% or more and 50 vol% or less are desirable. A more desirable range of the alumina content is 10 vol% or more and 45 vol% or less, and a further desirable range is 10 vol% or more and 40% or less.
[0054]
The tendency shown by FIG. 6 shows the same tendency also in the thermoelectric conversion unit 10 comprised using the thermoelectric conversion element containing inorganic materials other than alumina, such as quartz, mullite, titania, and zirconia.
[0055]
In FIG. 7, the atmosphere in the sealed container 15 included in the thermoelectric conversion unit 10 is an air atmosphere, a reduced pressure atmosphere, nitrogen (hereinafter, N ₂ The comparison of the power generation amount in the case of atmosphere and inert gas atmosphere is shown.
[0056]
The power generation amount shown in FIG. 7 is defined as 100, where the amount of power generated when the atmosphere in the sealed container 15 shown in FIG. Only the atmosphere in the sealed container 15 is changed to a reduced pressure atmosphere and N ₂ The amount of power generation when the atmosphere and the inert gas atmosphere are changed is shown as a relative value with respect to 100.
[0057]
According to FIG. 7, the reduced pressure atmosphere, N ₂ In the case of an atmosphere or inert gas atmosphere, even if the number of power generations is repeated 100 times, almost no decrease in the amount of power generation is seen, so the power generation ratio is 100% or more, which is about 110% to 120%. Yes. Therefore, the inside of the sealed container 15 has a reduced pressure atmosphere, N ₂ An atmosphere selected from either an atmosphere or an inert gas atmosphere is desirable.
[0058]
Moreover, as for the pressure in the airtight container in a pressure-reduced atmosphere, 9 kPa-100 kPa are desirable. And the more desirable range of the pressure in the airtight container in a pressure-reduced atmosphere is 9 kPa-80 kPa, More preferably, it is 9 kPa-60 kPa. On the other hand, N ₂ The pressure in the sealed container in the atmosphere or inert gas atmosphere is preferably 9 kPa to 110 kPa. And N ₂ The more desirable range of the pressure in the sealed container in the atmosphere or inert gas atmosphere is 30 kPa to 110 kPa, and more desirably 50 kPa to 110 kPa.
[0059]
In the thermoelectric conversion means 14 of the thermoelectric unit 10 shown in FIG. A power generation amount in the case of bonding using a solder (hereinafter referred to as a conventional bonding method) and a low melting point bonding material that is, for example, a tin / antimony material is bonded to the bonding material 22 by solder. Note that the low melting point bonding material refers to a material that melts in a solid state of tin, that is, a material having a melting point lower than the melting point of tin (232 ° C.).
[0060]
The power generation amount shown in FIG. 8 is shown as a relative value when the power generation amount in the conventional joining method is set to 100 when the low melting point bonding material is used for the bonding material 22. According to FIG. 8, the power generation ratio when the low melting point material is used for the bonding material 22 is about 170%, which is about 1 of the thermoelectric conversion unit (referred to as a conventional product in FIG. 8) bonded by the conventional bonding method. It turns out that it becomes .7 times. Therefore, the bonding material 22 used in the thermoelectric conversion unit 10 shown in FIG. 1 is desirably used from the viewpoint of increasing the amount of power generation, rather than using a conventionally used adhesive.
[0061]
In addition to the tin (Sn) / antimony (Sb) based material, the low melting point joining material used as the joining material 22 includes an aluminum (Al) based material, a copper (Cu) / lead (Pb) alloy based material, cadmium ( Cd) -based material, copper (Cu) / cadmium (Cd) -based material, alkali-cured lead-based material, zinc (Zn) -based material, and sintered oil-impregnated material. The same effect can be obtained.
[0062]
On the other hand, when deriving the characteristics shown in FIG. 8, the thermoelectric conversion unit 10 in which the low melting point bonding material as the bonding material 22 of the thermoelectric conversion unit 10 is bonded with solder is used. In addition to soldering, the same effect can be obtained by joining by overlaying, welding, or brazing. Furthermore, the thickness of the low melting point bonding material does not greatly affect the tendency of the power generation amount shown in FIG. 8, but is preferably 2 mm or less from the viewpoint of economy.
[0063]
According to the thermoelectric unit of the present embodiment, by maintaining the humidity in the sealed container 15 included in the thermoelectric conversion unit 10 at 0% to 1%, power generation of 95% or more of the initial power generation amount even if the number of repetitions is 100 times or more. It is possible to maintain the quantity.
[0064]
Further, the ratio of the pores contained in the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 used in the thermoelectric conversion means 14 included in the thermoelectric conversion unit 10, the kind and ratio of the inorganic material, and the inside of the sealed container 15 The amount of power generation can be increased by appropriately selecting the atmosphere. Furthermore, the amount of power generation can be increased by using a bonding material 22 for bonding the bonding conductor 17 and the electrode 19 provided in the thermoelectric conversion means 14 to the thermoelectric conversion mechanism 13 and the protective insulator 20 as a low melting point bonding material.
[0065]
In the present embodiment, the thermoelectric conversion means 14 covered with the protective insulator 20 is stored in the sealed container 15, but the thermoelectric conversion means 14 is not provided with the protective insulator 20. May be stored in the sealed container 15. Further, the non-conductive material used for the sealed container 15 may be a metal material obtained by performing non-conductive treatment such as insulating coating on the metal surface.
[0066]
[Second Embodiment]
An example of the thermoelectric conversion unit which shows 2nd Embodiment in FIGS. 9-11 is shown.
[0067]
The thermoelectric conversion units 10A to 10C shown in FIGS. 9 to 11 are thermoelectric conversion units including a heat supply source 25 and a power supply unit 26 having the same mechanism as the thermoelectric conversion unit 10 shown in FIG. There is a difference from the thermoelectric conversion unit 10 shown in FIG. 1 as a first embodiment of the thermoelectric conversion unit in that it includes a heat supply source 25 that performs thermoelectric conversion. The thermoelectric conversion unit 10A is essentially different from the heat supply source 25 except that the thermoelectric conversion unit 10A is essentially the same as the thermoelectric conversion unit 10 according to the first embodiment. Is omitted.
[0068]
FIG. 9 shows an example of a thermoelectric conversion unit 10 A using a water supply pipe for the heat supply source 25.
[0069]
The thermoelectric conversion unit 10A shown in FIG. 9 includes a water pipe having a device 29 (hereinafter referred to as an electrical device) that operates by consuming electric power such as a water meter that requires power supply as the heat supply source 25. And a power supply unit 26 and a power supply medium 30 that supplies power from the power supply unit 26 to the electrical device 29.
[0070]
The thermoelectric conversion unit 10 A takes out thermal energy using a temperature difference around a water pipe having a water meter as the electric device 29 as a heat supply source 25. The heat supply unit 25 is a thermoelectric conversion unit in which the power supply unit 26 and the power supply unit 26 are integrated with each other by using the heat energy from the heat supply source 25 to perform thermoelectric conversion in the power supply unit 26. The thermoelectric conversion unit 10A shown in FIG. 9 uses the temperature difference from the water temperature, the ground temperature, and the atmospheric temperature obtained through the water pipe as the heat supply source 25, and uses the extracted thermal energy as the thermoelectric conversion unit 10 shown in FIG. Thermoelectric conversion is performed by the power supply unit 26 having the same mechanism as in FIG. The electromotive force generated as a result of thermoelectric conversion by the power supply unit 26 provided in the thermoelectric conversion unit 10 A is configured to be usable as a power source for a water meter as the electric device 29.
[0071]
FIG. 10 shows an example of a thermoelectric conversion unit 10B as another example in the second embodiment.
[0072]
The thermoelectric conversion unit 10 B shown in FIG. 10 includes a gas pipe having a gas flow meter as the electric device 29, a power supply unit 26, and a power supply medium 30. The thermoelectric conversion unit 10 B generates power by performing thermoelectric conversion in the power supply unit 26 using the temperature difference from the gas temperature and the atmospheric temperature obtained through the gas pipe as the heat supply source 25. The power generated by the power supply unit 26 included in the thermoelectric conversion unit 10B shown in FIG. 10 is supplied to the gas flow meter as the electric device 29 by the power supply medium 30, and the gas flow meter is driven.
[0073]
Furthermore, FIG. 11 shows an example of a thermoelectric conversion unit 10C as another example in the second embodiment.
[0074]
A thermoelectric conversion unit 10C illustrated in FIG. 11 includes the thermoelectric conversion unit 10A illustrated in FIG. 9 and a battery 35 including a power supply control unit capable of controlling power supply.
[0075]
The thermoelectric conversion unit 10 C once stores the electromotive force obtained by the thermoelectric conversion in the battery 35 and operates the electric device 29 via the battery 35. The thermoelectric conversion unit 10 C including the battery 35 supplies a constant amount of power to the water meter as the electric device 29 even when the temperature near the heat supply source 25 changes and the power generation amount fluctuates and is unstable. can do. Further, since the battery 35 includes the power supply control means, the generated electricity can be supplied to a water meter as the electric device 29 when necessary.
[0076]
According to the thermoelectric unit of the present embodiment, since the thermoelectric unit includes the heat supply source 25 and the power supply unit 26 that performs thermoelectric conversion, for example, an apparatus having an electrical device 29 such as a water pipe having a water meter is provided. In the case of the thermoelectric conversion unit 10 A serving as the heat supply source 25, the temperature difference around the water pipe can be extracted as heat energy, and the electric device 29 can be operated with the electric power generated by the thermoelectric conversion performed by the power supply unit 26. Therefore, an external power source for operating the electric device 29 becomes unnecessary.
[0077]
Further, as another embodiment, the thermoelectric conversion unit 10C including the battery 35 including the power supply control unit has a constant power amount even when the temperature near the heat supply source 25 changes and the power generation amount is unstable. Can be supplied. Furthermore, by controlling the power supply by the power supply control means, it is possible to supply the electric power generated by the thermoelectric conversion unit 10C to the electric equipment 29 other than the water meter as the electric equipment 29 that is normally used.
[0078]
Although the battery 35 included in the thermoelectric conversion unit 10C is provided with the power supply control means, it is possible to supply a certain amount of power to the electric device 29 without the power supply control means. is there.
[0079]
【Effect of the invention】
According to the thermoelectric conversion unit according to the present invention, even when it is used repeatedly and used for a long time, the power generation amount at the first power generation can be maintained with almost no decrease in the power generation amount.
[0080]
Further, the thermoelectric conversion unit is a low environmental load type power supply device that directly converts heat energy into electric energy, and can stably generate power by utilizing a temperature difference around the thermoelectric conversion unit. And since the thermal energy to utilize can utilize the temperature difference which arises in a natural environment, the electric power supply which suppressed the power generation cost is attained.
[0081]
Furthermore, since the thermoelectric conversion means included in the thermoelectric conversion unit generates power by using the temperature difference between the surroundings, the thermoelectric conversion unit has a temperature difference and some electric equipment that operates by consuming electric power and the thermoelectric conversion unit. By forming an electrical equipment integrated thermoelectric conversion unit with a conversion unit, the electrical equipment provided in the electrical equipment integrated thermoelectric conversion unit operates with little or no power supplied from outside the thermoelectric conversion unit. It can be configured as possible.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a thermoelectric conversion unit according to the present invention.
FIG. 2 is a schematic configuration diagram of thermoelectric conversion means provided in the thermoelectric conversion unit according to the present invention.
FIG. 3 shows the relationship between the number of times of power generation and the ratio of power generation in the thermoelectric conversion unit when thermoelectric conversion is performed by changing the humidity in the sealed container provided in the thermoelectric conversion unit according to the present invention in a range of 0% to 10%. The correlation diagram which shows a relationship.
FIG. 4 is a correlation diagram showing a relationship between a ratio of pores in a thermoelectric element and a power generation ratio when thermoelectric conversion is performed by changing the ratio of pores in the thermoelectric element included in the thermoelectric conversion unit according to the present invention.
FIG. 5 is an explanatory diagram for explaining the relationship between the type of inorganic material and the power generation ratio when the thermoelectric conversion is performed by changing the type of inorganic material contained in the thermoelectric conversion element included in the thermoelectric conversion unit according to the present invention.
FIG. 6 shows the inorganic material content and the power generation ratio when the thermoelectric conversion is performed by changing the content (vol%) of alumina (inorganic material) contained in the thermoelectric element included in the thermoelectric conversion unit according to the present invention. FIG.
FIG. 7 is an explanatory diagram illustrating a relationship between an atmosphere in a sealed container provided in the thermoelectric conversion unit and a power generation ratio when the thermoelectric conversion is performed 100 times by the thermoelectric conversion unit according to the present invention.
FIG. 8 shows a case where a low-melting-point alloy material is used for the bonding surface between a heat source part and an electrode of the thermoelectric conversion unit and an electrode and an insulator when thermoelectric conversion is performed by the thermoelectric conversion unit according to the present invention, and an adhesive. Explanatory drawing explaining the relationship of the electric power generation amount ratio in the case of using.
FIG. 9 is an apparatus configuration diagram showing an embodiment of a thermoelectric conversion unit in which a thermoelectric conversion unit according to the present invention is attached to a water pipe and applied as a power supply source to a water meter.
FIG. 10 is an apparatus configuration diagram showing an embodiment of a thermoelectric conversion unit in which a thermoelectric conversion unit according to the present invention is attached to a gas pipe and applied as a power supply source to a gas meter.
FIG. 11 is an apparatus configuration showing an embodiment of a thermoelectric conversion unit in which a thermoelectric conversion unit according to the present invention is attached to a water pipe, the generated electricity is stored in a battery, and the battery is applied as a power supply source to a water meter. Figure.
FIG. 12 is a schematic view of a conventional thermoelectric conversion unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Thermoelectric conversion unit, 11 ... p-type thermoelectric conversion element, 12 ... n-type thermoelectric conversion element, 13 ... Thermoelectric conversion mechanism, 14 ... Thermoelectric conversion means, 15 ... Sealed container, 17 ... Connection conductor, 18a, 18b ... Power terminals, 19a, 19b ... electrodes, 20 ... surface protection insulator, 25 ... heat supply source, 26 ... power supply unit, 29 ... electric equipment, 30, 30a, 30b ... power supply medium, 35 ... battery.

Claims

A thermoelectric conversion mechanism having at least one p-type thermoelectric conversion element and n-type thermoelectric conversion element, and the plurality of electromotive forces generated by the thermoelectric conversion elements included in the thermoelectric conversion mechanism are extracted as one power supply device. A connection conductor for electrically connecting the thermoelectric conversion elements, and an electrode having a power supply terminal for extracting an electromotive force generated in the thermoelectric conversion mechanism from thermoelectric conversion elements located at both ends of the thermoelectric conversion mechanism joined by the connection conductor; A thermoelectric conversion part formed by bonding the connection conductor and the electrode and the thermoelectric conversion element with a bonding material;
A sealed container for storing and sealing the thermoelectric conversion unit so as to keep the humidity to a minimum is provided.
Thermoelectric conversion elements of a thermoelectric conversion elements and the n-type p-type having said thermoelectric conversion mechanism, bismuth (Bi) and tellurium (Te) as a main component, the p-type thermoelectric conversion elements and the n-type thermoelectric conversion element The inside porosity contains an inorganic material of 10% or more and 60% or less and 10% or more and 50% or less by volume, and the inorganic material is quartz, alumina, mullite, titania or zirconia. A thermoelectric conversion unit characterized by that.

_{2. The} thermoelectric conversion unit according to claim 1, wherein the atmosphere in the sealed container is selected from at least one of a reduced pressure atmosphere, a nitrogen (N ₂ ) atmosphere, and an inert gas atmosphere.

The thermoelectric conversion unit according to claim 1, wherein the pressure in the sealed container is 9 kPa to 110 kPa.

The thermoelectric conversion unit according to claim 1, wherein the bonding material is a low melting point bonding material that melts at a temperature lower than the melting point of tin (Sn).

The bonding material used as the bonding material is a low melting point bonding material that melts at a temperature lower than the melting point of tin (Sn), and the low melting point bonding material is tin (Sn) / antimony (Sb) based material, aluminum (Al ) Based material, copper (Cu) / lead (Pb) alloy based material, cadmium (Cd) based material, copper (Cu) / cadmium (Cd) based material, alkali hardened lead based material, zinc (Zn) based material, baked The thermoelectric conversion unit according to claim 1, wherein the thermoelectric conversion unit is composed of at least one selected from oil-containing materials.

The bonding material used as the bonding material is a low melting point bonding material that melts at a temperature lower than the melting point of tin (Sn), and the thickness of the low melting point bonding material is 2 mm or less. Thermoelectric conversion unit.