JP2008177356A

JP2008177356A - Thermoelectric power generation element

Info

Publication number: JP2008177356A
Application number: JP2007009363A
Authority: JP
Inventors: Kazuo Ebisumori; 一雄戎森
Original assignee: Aisin Seiki Co Ltd; Toyota Motor Corp
Current assignee: Toyota Motor Corp; Aisin Corp
Priority date: 2007-01-18
Filing date: 2007-01-18
Publication date: 2008-07-31

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric power generation element can be used in a high-temperature environment than in conventional structures, relaxing the thermal stresses so as not to damage the junction due to the difference of the thermal expansion between a thermoelectric material chip and an electrode, and suppressing the decrease in the generated output and generated efficiency. <P>SOLUTION: The thermoelectric power generation element 1 comprises an n-type and a p-type semiconductor 2, 3 electrically connected alternately in series by electrodes 4, 5 at their end parts, and at least either the n-type or the p-type semiconductor 2, 3 is connected to the electrode via a conductive elastic member 6 at least at one of the electrodes 4, 5 of the both end part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、温度差を利用して発電をさせること又は直流電流を供給することによって冷却若しくは加熱させることが可能な熱電発電素子に関する。 The present invention relates to a thermoelectric power generation element capable of generating power using a temperature difference or cooling or heating by supplying a direct current.

図３は従来型の熱電発電素子３１の側断面図を示す。図３（ａ）は、図において上側の電極が高温とされ、下側の電極がそれに較べて低温とされた直後の状態の熱電発電素子３１を示し、図３（ｂ）は、その上下の電極を図３（ａ）に較べてより温度の高低差のある状態にして一定時間経過した後の熱電発電素子３１を示す。 FIG. 3 is a sectional side view of a conventional thermoelectric generator 31. FIG. 3A shows the thermoelectric power generation element 31 in a state immediately after the upper electrode is set to a high temperature and the lower electrode is set to a low temperature compared to the upper electrode, and FIG. The thermoelectric power generation element 31 is shown after a certain period of time has elapsed with the electrodes in a state with a temperature difference that is higher than that in FIG.

熱電発電素子３１は、低温となる側の電極３５に、例えば半田等によって熱電材料チップであるｎ型半導体３２が接合され、ｎ型半導体３２の反対側の端部と高温となる側の電極３４とが同じく半田等によって接合されている。さらに同じ電極３４と熱電材料チップであるｐ型半導体３３とが接合され、ｐ型半導体３３の反対側の端部は別のｎ型半導体３２が接合された別の電極３５に接合されている。このような構成にすることによって電気的に直列した接続が完成する。 In the thermoelectric generator 31, an n-type semiconductor 32, which is a thermoelectric material chip, is joined to an electrode 35 on a low temperature side by solder or the like, for example, and an opposite end of the n-type semiconductor 32 and an electrode 34 on a high temperature side. Are joined together by solder or the like. Further, the same electrode 34 and a p-type semiconductor 33 which is a thermoelectric material chip are joined, and the opposite end of the p-type semiconductor 33 is joined to another electrode 35 to which another n-type semiconductor 32 is joined. With such a configuration, an electrical series connection is completed.

電極３４が高温、電極３５がそれに較べて低温となるような環境に熱電発電素子３１を設置して端部の電極を電気回路等に接続すると、ゼーベック効果によって電圧が発生し、矢印で示すように、電極３５→ｎ型半導体３２→電極３４→ｐ型半導体３３と電流が流れる。これはつまり、ｎ型半導体３２内の電子が高温の電極３４から熱エネルギーを得て低温の電極３５へ移動してそこで熱エネルギーを放出し、それに対してｐ型半導体の正孔が高温の電極３４から熱エネルギーを得て低温の電極３５へ移動してそこで熱エネルギーを放出するという原理によって電流が流れる。 When the thermoelectric power generation element 31 is installed in an environment in which the electrode 34 is at a high temperature and the electrode 35 is at a low temperature, and the end electrode is connected to an electric circuit or the like, a voltage is generated by the Seebeck effect, as indicated by an arrow. In addition, a current flows through the electrode 35 → the n-type semiconductor 32 → the electrode 34 → the p-type semiconductor 33. This means that electrons in the n-type semiconductor 32 obtain thermal energy from the high temperature electrode 34 and move to the low temperature electrode 35 where the thermal energy is released, whereas holes in the p type semiconductor are heated to the high temperature electrode. Current flows by the principle of obtaining thermal energy from 34 and moving to a low temperature electrode 35 where the thermal energy is released.

このような熱電発電素子３１の上下の電極３４，３５の温度差をさらに大きくすると、その温度差における熱電材料チップ及び電極間の熱膨張の違いによって、接合界面付近で破壊３６が生じてしまう。 When the temperature difference between the upper and lower electrodes 34 and 35 of the thermoelectric power generation element 31 is further increased, the destruction 36 occurs near the bonding interface due to the difference in thermal expansion between the thermoelectric material chip and the electrode at the temperature difference.

これを解決するために、シリコンゴムやウレタンゴム、高分子化合物等から作られた導電性の弾性体（導電性ゴム）を電極材料として用いることで、破壊の原因となる熱応力を緩和する構成が公知である（特許文献１）。 In order to solve this problem, a conductive elastic body (conductive rubber) made of silicon rubber, urethane rubber, polymer compound, etc. is used as an electrode material to reduce thermal stress that causes destruction. Is known (Patent Document 1).

特開２００３−１９７９８３号公報JP 2003-197983 A

しかしながら、上記構成によると、一般に導電性ゴム材料の耐熱温度は金属の融点に較べて低いため、より高温の環境において用いることができない。また、ゴムや高分子化合物は熱的にも電気的にも抵抗が大きいため、発電出力及び発電効率が低下するという問題もある。 However, according to the above configuration, since the heat resistant temperature of the conductive rubber material is generally lower than the melting point of the metal, it cannot be used in a higher temperature environment. In addition, since rubber and polymer compounds have large resistance both thermally and electrically, there is a problem that power generation output and power generation efficiency are lowered.

そこで本発明は上記問題に鑑み、従来の構造よりも高温な環境においても使用可能であって、熱電材料チップ及び電極間の熱膨張の差によって接合部が破壊しないように熱応力を緩和しつつ、発電出力及び発電効率の低下を抑えた熱電発電素子を提供することを目的とする。 Therefore, in view of the above problems, the present invention can be used in an environment where the temperature is higher than that of the conventional structure, while relaxing the thermal stress so that the joint portion is not broken due to the difference in thermal expansion between the thermoelectric material chip and the electrode. An object of the present invention is to provide a thermoelectric power generation element that suppresses a decrease in power generation output and power generation efficiency.

請求項１に記載の発明によれば、ｎ型及びｐ型の半導体がそれら端部で電極によって電気的に直列となるよう交互に接続された熱電発電素子において、ｎ型及びｐ型の半導体の少なくとも一方が両端部の電極の少なくとも一方で導電性の弾性部材を介して電極に接続されていることを特徴とする熱電発電素子が提供される。弾性部材を介して半導体である熱電材料チップと電極とが接続されているので、電極の熱膨張に差が生じても、それに起因した変形を弾性部材が吸収し、熱電材料チップ及び電極間の熱応力による破壊を防止することが可能となる。さらに、弾性部材に金属材料を用いれば、従来の導電性ゴムに較べてより高温域で熱電発電素子を使用することが可能となる。 According to the first aspect of the present invention, in a thermoelectric power generation element in which n-type and p-type semiconductors are alternately connected so as to be electrically connected in series by electrodes at their ends, the n-type and p-type semiconductors At least one of the electrodes at both ends is connected to the electrode through at least one of the conductive elastic members. A thermoelectric power generation element is provided. Since the thermoelectric material chip, which is a semiconductor, and the electrode are connected via the elastic member, even if a difference occurs in the thermal expansion of the electrode, the elastic member absorbs the deformation caused by the difference, and the thermoelectric material chip and the electrode are It becomes possible to prevent destruction due to thermal stress. Furthermore, if a metal material is used for the elastic member, it becomes possible to use the thermoelectric power generation element in a higher temperature range than the conventional conductive rubber.

また、請求項２に記載の発明によれば請求項１に記載の発明において、半導体及び電極間で弾性部材周囲を覆うように低融点金属が配置されていることを特徴とする熱電発電素子が提供される。弾性部材周囲に低融点金属が配置されることによって、弾性部材の耐久性が向上すると共に、熱電材料チップ及び電極間の電気的及び熱的抵抗を低減し、弾性部材のみの場合に較べて発電出力及び発電効率を向上させることが可能となる。 According to a second aspect of the present invention, there is provided the thermoelectric power generation element according to the first aspect, wherein the low melting point metal is disposed so as to cover the periphery of the elastic member between the semiconductor and the electrode. Provided. By arranging a low melting point metal around the elastic member, the durability of the elastic member is improved and the electrical and thermal resistance between the thermoelectric material chip and the electrode is reduced, so that power generation is possible compared to the case of only the elastic member. Output and power generation efficiency can be improved.

各請求項に記載の発明によれば、熱電発電素子において、従来の構造よりも高温な環境においても使用可能であって、電極の熱膨張の差による熱電材料チップ及び電極間の接合部の熱応力を緩和するという共通の効果を奏する。 According to the invention described in each claim, the thermoelectric power generation element can be used in an environment at a higher temperature than the conventional structure, and the heat of the junction between the thermoelectric material chip and the electrode due to the difference in thermal expansion of the electrode. It has the common effect of relieving stress.

図１は本発明の実施形態による熱電発電素子１の側断面図を示す。図１（ａ）は、図において上側が高温とされ、下側がそれに較べて低温とされた直後の状態の熱電発電素子１を示し、図１（ｂ）は、その上下の電極を図１（ａ）に較べてより温度の高低差のある状態にして一定時間経過した後の熱電発電素子１を示す。 FIG. 1 shows a side sectional view of a thermoelectric generator 1 according to an embodiment of the present invention. FIG. 1A shows the thermoelectric power generation element 1 in a state immediately after the upper side is set to a high temperature and the lower side is set to a lower temperature, and FIG. 1B shows the upper and lower electrodes of FIG. The thermoelectric power generation element 1 is shown after a certain time has passed in a state where the temperature difference is higher than in a).

熱電発電素子１は、低温となる側の電極５に、例えば半田等によって熱電材料チップであるｎ型半導体２が接合され、ｎ型半導体２の反対側の端部と高温となる側の電極４とが拡散接合等によって接合されている。さらに同じ電極４と熱電材料チップであるｐ型半導体３とが、導電性のコイルスプリング６を介して接続され、ｐ型半導体３の反対側の端部は別のｎ型半導体２が接合された別の電極５に接合されている。このような構成にすることによって電気的に直列した接続が完成する。さらに、コイルスプリング６が配置されているｐ型半導体３及び電極４間には、コイルスプリング６周囲を覆うように低融点金属部材７が配置され、そうすることによって、電導性のコイルスプリング６のみならず低融点金属部材７にも電流及び熱が伝わり、そのため導電性及び伝熱性が向上する。 In the thermoelectric generator 1, an n-type semiconductor 2, which is a thermoelectric material chip, is joined to the electrode 5 on the low temperature side by, for example, solder, and the opposite end of the n-type semiconductor 2 and the electrode 4 on the high temperature side. Are joined by diffusion bonding or the like. Further, the same electrode 4 and the p-type semiconductor 3 which is a thermoelectric material chip are connected via a conductive coil spring 6, and another n-type semiconductor 2 is joined to the opposite end of the p-type semiconductor 3. It is joined to another electrode 5. With such a configuration, an electrical series connection is completed. Further, a low-melting point metal member 7 is disposed between the p-type semiconductor 3 and the electrode 4 where the coil spring 6 is disposed so as to cover the periphery of the coil spring 6, so that only the conductive coil spring 6 is provided. In addition, current and heat are also transmitted to the low melting point metal member 7, so that conductivity and heat transfer are improved.

電極４，５の材料は、例えば、ＣｕやＴｉ−Ｃｕ合金であり、コイルスプリング６の材料は、例えば、無酸素銅線やすずめっき銅線であり、熱電発電素子１の材料は、例えば、クラスレート系やハーフホイスラー系であり、低融点金属部材７の材料は、例えば、Ｚｎ、Ｓｎ、Ｂｉ、アルミろう、高融点はんだ（Ｓｎ−Ｃｕ系）である。 The material of the electrodes 4 and 5 is, for example, Cu or Ti—Cu alloy, the material of the coil spring 6 is, for example, an oxygen-free copper wire or a tin-plated copper wire, and the material of the thermoelectric power generation element 1 is, for example, The material of the low melting point metal member 7 is, for example, Zn, Sn, Bi, aluminum brazing, or high melting point solder (Sn—Cu type).

電極４が例えば３００℃から６００℃の高温、電極５が例えば２５℃から１００℃の低温となるような環境に、本発明の実施形態による熱電発電素子１を設置して端部の電極を電気回路等に接続すると、矢印で示すように、電極５→ｎ型半導体２→電極４→ｐ型半導体３と電流が流れる。 In an environment in which the electrode 4 is at a high temperature of, for example, 300 ° C. to 600 ° C. and the electrode 5 is at a low temperature of, for example, 25 ° C. to 100 ° C., the thermoelectric power generation element 1 according to the embodiment of the present invention is installed. When connected to a circuit or the like, current flows through electrode 5 → n-type semiconductor 2 → electrode 4 → p-type semiconductor 3 as indicated by an arrow.

さらに温度差を大きくして一定時間経過させると、高温側の電極４と低温側の電極５との間で熱膨張の差が生じるが、図１（ｂ）に示すように、コイルスプリング６及び液化した低融点金属部材７が熱膨張に合わせて変形し、従来の破壊の原因となっていた熱応力を緩和する働きをすることとなる。両電極間の温度差が小さくなれば、コイルスプリング６の弾性によってまたもとの状態に戻ることが可能となる。なお、液化した低融点金属は、表面張力等によってｐ型半導体３及び電極４間に維持される。 When the temperature difference is further increased and a certain period of time elapses, a difference in thermal expansion occurs between the high temperature side electrode 4 and the low temperature side electrode 5, but as shown in FIG. The liquefied low melting point metal member 7 is deformed in accordance with the thermal expansion and functions to alleviate the thermal stress that has been the cause of the conventional destruction. If the temperature difference between the two electrodes is reduced, it is possible to return to the original state by the elasticity of the coil spring 6. The liquefied low melting point metal is maintained between the p-type semiconductor 3 and the electrode 4 by surface tension or the like.

ここで、本発明の実施形態による熱電発電素子１の製造方法を図２の側断面図に沿って工程順に説明する。 Here, the manufacturing method of the thermoelectric power generation element 1 according to the embodiment of the present invention will be described in the order of steps along the side sectional view of FIG.

まず、電極４とｎ型半導体２とを拡散接合によって接合する（図２（ａ））。そして、ｐ型半導体３と電極４とをコイルスプリング６を介して接続するために、コイルスプリング６の両端でそれぞれレーザースポット溶接を行って接合する（図２（ｂ））。さらに、ｐ型半導体３及び電極４間にコイルスプリング６周囲を覆うように低融点金属部材７を配置するため、低融点金属を注入する（図２（ｃ））。そして、低温側の電極５を半田付けするための濡れ性向上のため、メッキ８を施し（図２（ｄ））、最後に、電極５を半田付け９して完成となる（図２（ｅ））。 First, the electrode 4 and the n-type semiconductor 2 are joined by diffusion bonding (FIG. 2A). Then, in order to connect the p-type semiconductor 3 and the electrode 4 via the coil spring 6, laser spot welding is performed at both ends of the coil spring 6 respectively (FIG. 2B). Further, in order to dispose the low melting point metal member 7 so as to cover the periphery of the coil spring 6 between the p-type semiconductor 3 and the electrode 4, a low melting point metal is injected (FIG. 2C). Then, in order to improve wettability for soldering the electrode 5 on the low temperature side, plating 8 is applied (FIG. 2D), and finally, the electrode 5 is soldered 9 to complete (FIG. 2E). )).

本実施形態は、コイルスプリング及び低融点金属部材をｐ型半導体の高温となる側にのみ配置したが、それ以外にも、ｎ型半導体の高温となる側若しくは低温となる側又はｐ型半導体の高温となる側若しくは低温となる側の少なくとも１つに配置されていればよいが、好ましくは、低融点金属部材の材料の選択の幅が広いｎ型半導体又はｐ型半導体の高温となる側の少なくとも１つに配置されていることが望ましい。また、本実施形態は、コイルスプリングと低融点金属部材を併用したが、低融点金属部材を排除し、導電性が高くて熱抵抗が少ない金属等の部材からなるコイルスプリングのみで構成されていてもよい。さらに、本実施形態は、コイルスプリングを用いたが、電極平面方向の膨脹に弾性を有する板バネ等の弾性部材であれば代替可能である。 In the present embodiment, the coil spring and the low melting point metal member are arranged only on the high temperature side of the p-type semiconductor, but other than that, the high temperature side or the low temperature side of the n type semiconductor or the p type semiconductor It is sufficient that it is disposed on at least one of the high temperature side or the low temperature side, but preferably, the low melting point metal member has a wide selection range of materials of the n-type semiconductor or p-type semiconductor. It is desirable to arrange at least one. Moreover, although this embodiment used the coil spring and the low-melting point metal member in combination, the low-melting point metal member is excluded, and only the coil spring made of a member such as a metal having high conductivity and low thermal resistance is used. Also good. Furthermore, although the present embodiment uses a coil spring, it can be replaced if it is an elastic member such as a leaf spring that has elasticity for expansion in the electrode plane direction.

本発明の実施形態による熱電発電素子の側断面図である。It is a sectional side view of the thermoelectric power generation element by embodiment of this invention. 本発明の実施形態による熱電発電素子の製造方法を工程順に示す側断面図である。It is a sectional side view which shows the manufacturing method of the thermoelectric power generation element by embodiment of this invention in process order. 従来の熱電発電素子の側断面図である。It is a sectional side view of the conventional thermoelectric power generation element.

符号の説明Explanation of symbols

１熱電発電素子
２ｎ型半導体
３ｐ型半導体
４，５電極
６コイルスプリング
７低融点金属 DESCRIPTION OF SYMBOLS 1 Thermoelectric power generation element 2 N-type semiconductor 3 P-type semiconductor 4,5 Electrode 6 Coil spring 7 Low melting point metal

Claims

ｎ型及びｐ型の半導体がそれら端部で電極によって電気的に直列となるよう交互に接続された熱電発電素子において、ｎ型及びｐ型の半導体の少なくとも一方が両端部の電極の少なくとも一方で導電性の弾性部材を介して電極に接続されていることを特徴とする熱電発電素子。 In a thermoelectric power generation element in which n-type and p-type semiconductors are alternately connected so as to be electrically connected in series by electrodes at their ends, at least one of the n-type and p-type semiconductors is at least one of the electrodes at both ends. A thermoelectric power generation element connected to an electrode through a conductive elastic member.

半導体及び電極間で弾性部材周囲を覆うように低融点金属が配置されていることを特徴とする請求項１に記載の熱電発電素子。 The thermoelectric power generation element according to claim 1, wherein a low melting point metal is disposed between the semiconductor and the electrode so as to cover the periphery of the elastic member.