200933968 ❹ 10 15 ❹ 六、發明說明： I：發明戶斤屬之技術領域3 相關申請案之交又參考 此申請案對於2〇〇7年10月23日於韓國智財局提中的# 5 國專利申請案10-2007-0106745作權利主張，其揭示被整 合併於本文中以供參考。 發明領域 本發明的一示範性實施例係有關一用於測量液體_ & 濃度之設備及一包括該設備之燃料電池，且更特別有_ 使用一應變儀來測量液體燃料濃度之設備，及 備之燃料電池。 【先前^14幹 相關技藝描述 身為藉由作為氧化劑的氧與一諸如甲醇或乙 化合物燃料之電化反應來產生電力的發電系統之胃 燃料電池係因為直接使用一諸如甲醇等液體燃料所Μ## 高的能量及功率密度，不需要諸如重組器等周邊裝置，' 容易儲存及供應燃料。 在直接液體燃料電池之中，使用甲醇及水作為燃 合物的直接甲醇燃料電池(DMFC)係產生電極反應，包括_ 令燃料被氧化的氧化反應（陽極電極反應）及一令氫離子及 氧被還原的還原反應（陰極電極反應）。在氧化反應中，甲醇 及水彼此起反應，產生二氧化碳、氫離子及電子，且氫離 子經由薄膜被轉移至一陰極電極。在還原反應中，氫離子、 包括該設 且 20 200933968 經由一外部電路所轉移的電子、及氧係彼此起反應，且產 生水。因此，DMFC的整體反應藉由甲醇及氧的一反應來產 生水及一氧化碳。因此，DMFC必須使用甲醇溶液形式的甲 醇而非純甲醇，其亦即身為一 DMFC系統中所產生或已先行 5儲存其中之純甲醇及水的一混合物之低濃度水性甲醇溶 液。當DMFC使用高濃度甲醇時，甲醇被跨越（甲醇穿過薄 膜且然後）’ 一電池電壓由於甲醇的氧化而被降低。 然而’當DMFC使用低濃度甲醇時，其需要一很佔體積 的燃料儲存槽，這並不適合DMFC的設計。為了解決此問 10題，使用濃縮的甲醇或純甲醇作為燃料，且此高濃度甲醇 根據DMFC的操作條件被稀釋。因此，對於使用高濃度甲醇 作為燃料之DMFC系統而言，用於精密地測量甲醇濃度之甲 醇感測器很重要。 習知已經使用諸如利用一薄膜電極總成(MEA)、利用 15燃料黏度、利用差壓的方法及類似方法等用於測量不同液 體燃料的濃度之方法、及進行該方法之設備。 美國專利案6,303,244揭露一用於偵測一流通槽中的甲 醇濃度之甲醇感測器，但並未揭露甲醇感測器的詳細結構。 美國專利案6,488,837揭露一甲醇感測器，其包含一 20 MEA，一陽極電流收集器，一陰極電流收集器，及一電流 感測器。電流感測器測量一橫越陽極電流收集器及陰極電 流收集器之短路的電流藉以提供與一甲醇水性溶液的曱醇 濃度呈函數性相聯結之輸出信號。亦即，根據甲醇濃度之 甲醇水性溶液導電性的變化係以一輸出電流被测量。 200933968 美國公開專利案2006/0272943揭露一用於測量一水性 溶液燃料濃度之電化感測器，其包含一MEA，兩個電流收 集器，一陽極端板，及一陰極端板。電化感測器根據水性 溶液燃料濃度提供一輸出信號。更詳言之，根據諸如甲醇、 5 乙醇、或甲酸等有機燃料及諸如硼氫化鉀或鈉等無機燃料 的濃度之液體燃料導電性的變化係以輸出電流被測量。200933968 ❹ 10 15 ❹ VI. Description of the invention: I: The technical field of the invention of the households. 3 The relevant application is also referred to this application for #5 on October 23, 2007 at the Korea Intellectual Property Office. Patent Application No. 10-2007-0106745, the disclosure of which is incorporated herein by reference. FIELD OF THE INVENTION An exemplary embodiment of the present invention relates to an apparatus for measuring a concentration of a liquid and a fuel cell including the apparatus, and more particularly, an apparatus for measuring a liquid fuel concentration using a strain gauge, and Prepared fuel cell. [Previously, the related art describes a gastric fuel cell system which is a power generation system which generates electricity by electrochemical reaction of oxygen as an oxidant with a fuel such as methanol or a compound of a compound, because a liquid fuel such as methanol is directly used. #高能量能量和功率密度, does not require peripheral devices such as recombiners, 'easy to store and supply fuel. Among direct liquid fuel cells, direct methanol fuel cells (DMFC) using methanol and water as fuel compounds produce electrode reactions, including oxidation reactions in which the fuel is oxidized (anode electrode reaction) and a hydrogen ion and oxygen Reduced reduction reaction (cathode electrode reaction). In the oxidation reaction, methanol and water react with each other to generate carbon dioxide, hydrogen ions and electrons, and hydrogen ions are transferred to a cathode electrode via a film. In the reduction reaction, hydrogen ions, electrons transferred via an external circuit including the device 20 200933968, and oxygen react with each other to generate water. Therefore, the overall reaction of the DMFC produces water and carbon monoxide by a reaction of methanol and oxygen. Therefore, the DMFC must use methanol in the form of a methanol solution instead of pure methanol, which is a low concentration aqueous methanol solution which is produced in a DMFC system or which has been previously stored as a mixture of pure methanol and water. When the DMFC uses a high concentration of methanol, methanol is crossed (methanol passes through the film and then). A cell voltage is lowered due to oxidation of methanol. However, when the DMFC uses a low concentration of methanol, it requires a very large volume of fuel storage tank, which is not suitable for DMFC design. In order to solve this problem, concentrated methanol or pure methanol was used as a fuel, and this high concentration of methanol was diluted according to the operating conditions of the DMFC. Therefore, for a DMFC system using a high concentration of methanol as a fuel, a methanol sensor for precisely measuring the methanol concentration is important. Conventionally, methods for measuring the concentrations of different liquid fuels, such as using a thin film electrode assembly (MEA), utilizing a viscosity of 15 fuel, a method using differential pressure, and the like, and apparatus for carrying out the method have been used. U.S. Patent No. 6,303,244 discloses a methanol sensor for detecting the concentration of methanol in a flow cell, but does not disclose the detailed structure of the methanol sensor. U.S. Patent No. 6,488,837 discloses a methanol sensor comprising a 20 MEA, an anode current collector, a cathode current collector, and a current sensor. The current sensor measures a current across the short circuit of the anode current collector and the cathode current collector to provide an output signal that is functionally coupled to the sterol concentration of an aqueous methanol solution. That is, the change in conductivity of the methanol aqueous solution according to the methanol concentration is measured as an output current. An electrochemical sensor for measuring the concentration of an aqueous solution fuel is disclosed in US Patent Publication No. 2006/0272943, which comprises an MEA, two current collectors, an anode end plate, and a cathode end plate. The electrochemical sensor provides an output signal based on the aqueous solution fuel concentration. More specifically, the change in conductivity of a liquid fuel based on the concentration of an organic fuel such as methanol, 5 ethanol, or formic acid, and an inorganic fuel such as potassium borohydride or sodium is measured as an output current.
美國專利案6,536,262揭露一藉由將一旁通線路裝設在 一液體燃料供應線路中來測量醇濃度且利用旁通線路的一 入口與出口中的差壓之方法。 10 韓國公開專利案2006-0064978揭露一用於測量曱醇濃 度之設備，該設備包含一感測器，其藉由液體燃料黏度變 化所造成的一支撐樑的變形來產生一電信號。 除了該等濃度測量方法外，亦已使用利用折射率 (www.ti.com)、超音波(www.murata.com)、液體燃料的質量 15 密度(www.mems-issys.com)之方法及類似方式。 L發明内容3 發明概要 本發明的一示範性實施例提供一用於測量液體燃料濃 度之設備，其使用一應變儀。 20 本發明的一示範性實施例係提供一用於容易地測量液 體燃料濃度之設備藉以因其具有一簡單結構來降低製造成 本。 本發明的一示範性實施例提供一燃料電池，其包括用 於測量液體燃料濃度之設備。 5 200933968 根據本發明的一態樣，提供一用於測量液體燃料濃度 之設備，該設備包含：一主體部單元，其包含一用於液體 燃料之流通路；一應變薄膜，其根據液體燃料濃度變化而 變形且配置於主體部單元中以使應變薄膜部份地暴露於流 5 通路；一應變儀，其配置於應變薄膜上且以應變儀的電阻 變化來偵測應變薄膜的應變；及一電路單元，其電性連接 至應變儀且將應變儀的電阻變化轉換成一輸出信號。 根據本發明另一態樣，提供一直接曱醇燃料電池，其 採用用於測量液體燃料濃度之上述設備。 10 圖式簡單說明 將藉由參照圖式詳細地描述本發明的實施例而進一步 得知本發明的上述及其他特徵構造及優點，其中： 第1圖為顯示根據本發明的一實施例之一用於測量液 體燃料濃度之設備的橫剖視圖； 15 第2圖為顯示根據本發明的一實施例如第1圖所示之一 應變薄膜及堆疊其上的一應變儀之橫剖視圖； 第3圖為顯示根據本發明另一實施例之一應變薄膜及 堆疊其上的一應變儀之橫剖視圖； 第4圖為顯示根據本發明的一實施例之第1圖所示的應 20 變儀之分解立體圖； 第5及6圖為說明根據本發明的一實施例之第1圖所示 用於測量液體燃料濃度之設備的操作之圖式。 I：實施方式3 較佳實施例之詳細說明 200933968 下文中，將參照圖式詳細地描述根據本發明的實施例 之一用於測量液體燃料濃度之設備。 5 ❺ 10 15 ❹ 第1圖為顯示根據本發明的一實施例之一用於測量液 體燃料濃度之設備10的橫剖視圖。第2圖為顯示根據本發明 的一實施例之一應變薄膜12及堆疊其上的一應變儀13之橫 剖視圖。 參照第1圖，用於測量液體燃料濃度之設備1〇係包含一 主體部單元U，應變薄膜12,應變儀13，及一電路單元15。 液體燃料的一主流通路11a及一旁通流通路llb形成於 主體部單元11中。雖然本實施例中形成主流通路lla及旁通 流通路lib兩者，可能並未形成旁通流通路Ub。然而，當 沿著主流通路lla發生一壓力偏差時，旁通通路Ub移除壓 力偏差，故壓力偏差會排除對於應變薄膜12的應變之效 應，其將於稍後描述。可使用諸如甲醇及乙醇等醇作為液 體機料。然而’本發明不在此限且可使用不同的其他有機 化合物作為液體燃料。主體部單元u包括一溝槽nc，其含 有應變薄膜12，應變儀13，及電路單元15。 主體部單元11設計成對於壓力及溫度變化並不敏感， 因為此等變化係影響應變薄膜12的應變，其導致測量應變 時之誤差增大。因此’需要根據壓力及溫度變化來嬌正應 變薄額之應變的變化。主體部單元u可進—步包含多種 不同用於矯正壓力及/或溫度的裝置(未圖示)。 以使應變薄膜12的至少—部份可暴露於主流通路心 〆旁通流通路llb之方式將應㈣膜i2配置於主體部⑽ 20 200933968 溝槽lie中。本實施例中，應變薄膜12部份地暴露於旁通流 通路lib。應變薄膜12根據液體燃料濃度變化而變形。更詳 言之，液體燃料濃度愈高，則應變薄膜12的應變愈大。因 此’應變薄膜12可根據液體燃料類型由不同材料形成。並 5 且’應變薄膜12具有足夠變形及恢復力藉以根據液體燃料 ‘ 濃度變化來增高或降低其應變。 同時，應變薄膜12可具有約ΙΟμπι及約500μιη之間的厚 度。若應變薄膜12的厚度小於ΙΟμπι，當液體燃料濃度在增 高之後再度降低時應變薄膜12難以恢復至其原始狀態。若 @ 10應變薄膜12的厚度大於500μιη，應變薄膜12的應變根據液 體燃料濃度變化而極端地降低。 參照第1及2圖，應變薄膜12具有一雙重薄膜結構，其 包括—第一薄膜12a及一第二薄膜12b。更詳言之，第二薄 膜1215配置於第一薄膜12a的一表面上，亦即與主流通路Ua 15及旁通流通路lib相對之第一薄膜12a的一表面。第一薄膜 12a含有根據液體燃料濃度變化而變形之至少一材料。第二 :U.S. Patent No. 6,536,262 discloses a method of measuring the concentration of alcohol by using a bypass line in a liquid fuel supply line and utilizing the differential pressure in an inlet and outlet of the bypass line. An apparatus for measuring the concentration of sterol is disclosed in the Korean Patent Publication No. 2006-0064978. The apparatus comprises a sensor for generating an electrical signal by deformation of a support beam caused by a change in viscosity of the liquid fuel. In addition to these concentration measurement methods, methods using refractive index (www.ti.com), ultrasonic (www.murata.com), liquid fuel mass 15 density (www.mems-issys.com), and A similar way. SUMMARY OF THE INVENTION 3 SUMMARY OF THE INVENTION An exemplary embodiment of the present invention provides an apparatus for measuring the concentration of a liquid fuel using a strain gauge. An exemplary embodiment of the present invention provides an apparatus for easily measuring a liquid fuel concentration whereby a manufacturing structure is reduced in order to reduce manufacturing costs. An exemplary embodiment of the present invention provides a fuel cell including an apparatus for measuring a liquid fuel concentration. 5 200933968 According to an aspect of the present invention, an apparatus for measuring a concentration of a liquid fuel is provided, the apparatus comprising: a body unit including a flow passage for a liquid fuel; and a strain film according to a liquid fuel concentration Varyingly deformed and disposed in the body portion unit to partially expose the strained film to the flow path 5; a strain gauge disposed on the strained film and detecting the strain of the strained film by a change in resistance of the strain gauge; and A circuit unit electrically connected to the strain gauge and converting the resistance change of the strain gauge into an output signal. According to another aspect of the present invention, a direct sterol fuel cell is provided which employs the above apparatus for measuring the concentration of a liquid fuel. BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the detailed description of the embodiments of the invention. A cross-sectional view of an apparatus for measuring a liquid fuel concentration; 15 Fig. 2 is a cross-sectional view showing a strain film according to an embodiment of the present invention, and a strain gauge stacked thereon; A cross-sectional view showing a strain gauge and a strain gauge stacked thereon according to another embodiment of the present invention; and FIG. 4 is an exploded perspective view showing the strain gauge according to the first embodiment of the present invention. 5 and 6 are diagrams illustrating the operation of the apparatus for measuring the concentration of liquid fuel shown in Fig. 1 according to an embodiment of the present invention. I: Embodiment 3 Detailed Description of Preferred Embodiments 200933968 Hereinafter, an apparatus for measuring a liquid fuel concentration according to an embodiment of the present invention will be described in detail with reference to the drawings. 5 ❺ 10 15 ❹ Fig. 1 is a cross-sectional view showing an apparatus 10 for measuring a liquid fuel concentration according to an embodiment of the present invention. Fig. 2 is a cross-sectional view showing a strain film 12 and a strain gauge 13 stacked thereon in accordance with an embodiment of the present invention. Referring to Fig. 1, an apparatus 1 for measuring a liquid fuel concentration includes a main body unit U, a strain film 12, a strain gauge 13, and a circuit unit 15. A main flow path 11a and a bypass flow path 11b of the liquid fuel are formed in the main body unit 11. Although both the main flow path 11a and the bypass flow path lib are formed in this embodiment, the bypass flow path Ub may not be formed. However, when a pressure deviation occurs along the main flow path 11a, the bypass path Ub removes the pressure deviation, so the pressure deviation excludes the effect on the strain of the strained film 12, which will be described later. Alcohols such as methanol and ethanol can be used as the liquid material. However, the invention is not limited thereto and different other organic compounds may be used as the liquid fuel. The body unit u includes a groove nc containing a strain film 12, a strain gauge 13, and a circuit unit 15. The body portion unit 11 is designed to be insensitive to pressure and temperature variations because these variations affect the strain of the strained film 12, which results in an increase in error in measuring strain. Therefore, it is necessary to refine the strain change due to the change in pressure and temperature. The body unit u can further comprise a plurality of different means (not shown) for correcting pressure and/or temperature. The film (i) film i2 is disposed in the body portion (10) 20 200933968 trench lie such that at least a portion of the strain film 12 can be exposed to the main channel via bypass flow path 11b. In this embodiment, the strained film 12 is partially exposed to the bypass flow path lib. The strained film 12 is deformed in accordance with a change in the concentration of the liquid fuel. More specifically, the higher the liquid fuel concentration, the greater the strain of the strained film 12. Therefore, the strain film 12 can be formed of different materials depending on the type of liquid fuel. And the strain film 12 has sufficient deformation and restoring force to increase or decrease the strain according to the liquid fuel 'concentration change. Meanwhile, the strain film 12 may have a thickness of between about ΙΟμm and about 500 μm. If the thickness of the strained film 12 is less than ΙΟμm, the strained film 12 is difficult to return to its original state when the liquid fuel concentration is lowered again after the increase. If the thickness of the @10 strained film 12 is more than 500 μm, the strain of the strained film 12 is extremely lowered in accordance with the change in the liquid fuel concentration. Referring to Figures 1 and 2, the strain film 12 has a double film structure including a first film 12a and a second film 12b. More specifically, the second film 1215 is disposed on a surface of the first film 12a, that is, a surface of the first film 12a opposite to the main flow path Ua 15 and the bypass flow path lib. The first film 12a contains at least one material which is deformed in accordance with a change in the concentration of the liquid fuel. Second:
薄膜12b含有並未根據液體燃料濃度變化而變形之至少一 Q 材料。更詳言之，第一薄膜12a可由一可供液體燃料至少一 部份穿過之材料形成。若第一薄膜12a根據液體燃料濃度變 20 化而變形’堆疊在第一薄膜12a上之第二薄膜12b係變形。 其後，雉疊在第二薄膜12b上之應變儀13係變形，其改變應 變儀13的電阻，藉以偵測液體燃料濃度的變化。這將在梢 後更詳細地描述。 第二·薄膜12b可為防水藉以不傳輸液體燃料。若第二薄 8 200933968 5 ❹ 10 15 ❹ 20 膜12b可滲透水，液體燃料將順序性傳輸過第一薄膜12a及 第二薄膜12b並弄濕應變儀13，其造成應變儀〗3的一電性短 路。為了防止發生電性短路，需要額外地裝設一分離的防 水薄膜或改變用於測量液體燃料濃度之設備10的結構，其 使得用於測量液體燃料濃度之設備iO的結構及製造製程變 得複雜。同時’第二薄膜12b可滲水藉以傳輸液體燃料。在 此例中，應變儀13必須為防水。 本實施例中’若液體燃料為醇，第一薄膜12a可為一聚 合物薄膜，其包含一磺酸基團（S03H)、一磷酸基團 (H2P〇4)、一羥基團（OH)、一羧基團（COOH)及類似物之至 少一者，且第二薄膜12b可為一聚合物薄膜，其包含聚偏二 氟乙烯(PVDF)、聚醚醚酮(PEEK)、聚碳酸酯（PC)及類似物 之至少一者，但本發明不在此限。 下文中，第1及2圖中的類似編號代表類似的元件或類 似元件的部分。 參照第3圖，應變薄膜12可為含有根據液體燃料濃度變 化而變形的至少一材料之單一薄膜。在此例中，應變薄膜 12可由與第一薄膜12a相同的材料形成並具有約ι〇μιη至約 500μηι間的一厚度。然而’為了防止發生電性短路，應變 儀13可包含一防水絕緣基材（未圖示）’ 一配置於絕緣基材内 側之金屬電阻線路（未圖示）’及一經絕緣的引導線路(未圖 示）。 應變儀13係為一配置於應變薄膜12上並以電阻變化根 據液體燃料濃度變化來债測應變薄膜12應變之裝置。 9 200933968 第4圖為顯示根據本發明的一實施例之第1圖所示的應 變儀13之分解立體圖。應變係為一種發生於物體中的變 形，並被定義為受到拉力或壓縮力時物體的拉伸或壓縮長 度對於原始長度之比值。亦即，應變係為一種代表被一内 5 部或外部力引發之一物體的變形測量之用語。 參照第4圖，應變儀13可為兩型應變儀其中之一：一電 性應變儀及一機械性應變儀。電性應變儀藉由測量被附接 至其中已發生變形的物體之應變儀電阻變化來測量一物體 的應變。機械性應變儀係藉由機械性測量物體在變形前與 10 變形後位於兩點之間的一細微距離變化來測量物體的應 變。本實施例中，雖然如第4圖所示使用電性應變儀，本發 明不在此限而是亦可使用機械性應變儀。雖然第4圖顯示單 軸線儀，本發明不在此限並亦可使用諸如兩軸線圓花儀 (rosette gauge)或三軸線圓花儀等電性應變儀。 15 應變儀13包括位於一諸如紙或塑料等絕緣基材13a上 或中之一很細薄的金屬電阻線路13b。金屬電阻線路13b為 一使兩端連接至兩引導線路14之線圈形式。應變儀13係為 一用於以電信號偵測小機械應變之感測器。更詳言之，若 應變儀13附接至應變薄膜12的表面，應變儀13可以電阻變 20 化來測量發生於應變薄膜12表面上之一細微維度變化、亦 即應變，並從變化大小求出液體燃料濃度。更詳言之，應 變儀13係為一種其中使一電阻裝置長度的應變（變形）與電 阻裝置中的電阻變化率呈正比之電阻的應用。並且，長度 的應變以及電阻變化率之比值係稱為儀因數（gauge 200933968 5 ❹ 10 15 Ο 20 factor),其由應變儀製造廠提供。因此，藉由儀因數可能從 電阻量的變化計算出長度的應變。長度的應變與液體燃料 的濃度成正比，藉以從電阻量變化來獲得液體燃料濃度。 經測量的應變係以諸如—橋電路的輸出電壓或輸出電流等 輸出k號作代表，其將在稍後描述。 當一拉力F被施加至應變儀13時，儀因數尺、長度變化 率△ L/L、應變ε、及電阻變化率△ r/r係如下列等式丨表示： Κ=( Δ R/R)/( Δ L/L)=( Δ R/R)/ ε » 亦即△ R/R =Κ*ε ......(1) 電路單元15經由引導線路14電性連接至應變儀13並將 應變儀13的電阻變化轉換成一輸出信號、輸出電壓、或輸 出電流。本實施例中，電路單元15包含惠斯登電橋…^以仙 bridge)的一部份及選擇性包含一放大器。稍後將詳述惠斯 登電橋及放大器之構造及效應。 第5及6圖為說明根據本發明的一實施例之第1圖所示 用於測量液體燃料濃度之設備1〇的操作之圖式。 第5圖為顯示自與第1圖所示用於測量液體燃料濃度之 堍備10中所包括者相同的元件所部份地抽取之省略旁通流 通路lib的主體部單元11、應變薄膜12及應變儀13之橫剖視 圖。第6圖為說明一用於測量藉由應變儀13以輸出電壓變化 所偵測的電阻變化之方法的圖式。 參照第5及4圖，當液體燃料在一箭頭方向中沿著主流 通路11a流動時，液體燃料經由第—薄骐12a的表面部份地 流入第一薄膜12a中。此液體燃料流係使第一薄膜12a變形 11 200933968 以令第-薄膜12a在一特定方向 12附接之第二薄膜 J 一乐 f 〜1係在與第-_l2af折的相 因此與第一薄臈 同方向 的應變儀！3在與第二薄則.’、續至第1 變儀13的此變形係導致配置於應變儀：中方::屬之棒應 第二薄膜⑶的此彎折係提供附接至第二薄膜12b 彎折。應 13b的電阻變化。 ，-见巧電阻線路 成用2第6及1圖’應變儀13電性連接至電路單元15並構 I〜成惠斯登電橋之四個電阻器&至⑽―電㈣ 10 15The film 12b contains at least one Q material that is not deformed according to a change in liquid fuel concentration. More specifically, the first film 12a may be formed of a material through which at least a portion of the liquid fuel can pass. If the first film 12a is deformed according to the liquid fuel concentration, the second film 12b stacked on the first film 12a is deformed. Thereafter, the strain gauge 13 folded over the second film 12b is deformed, which changes the resistance of the strainer 13 to detect a change in the concentration of the liquid fuel. This will be described in more detail later. The second film 12b may be waterproof so as not to transport liquid fuel. If the second thin film 8 200933968 5 ❹ 10 15 ❹ 20 membrane 12b is permeable to water, the liquid fuel will be sequentially transported through the first film 12a and the second film 12b and wet the strain gauge 13, which causes an electric strain of the strain gauge Sexual short circuit. In order to prevent the occurrence of an electrical short circuit, it is necessary to additionally install a separate waterproof film or to change the structure of the apparatus 10 for measuring the liquid fuel concentration, which complicates the structure and manufacturing process of the apparatus iO for measuring the liquid fuel concentration. . At the same time, the second film 12b can be permeable to water to transport liquid fuel. In this case, the strain gauge 13 must be waterproof. In the present embodiment, if the liquid fuel is an alcohol, the first film 12a may be a polymer film comprising a sulfonic acid group (S03H), a monophosphate group (H2P〇4), a hydroxyl group (OH), At least one of a carboxyl group (COOH) and the like, and the second film 12b may be a polymer film comprising polyvinylidene fluoride (PVDF), polyetheretherketone (PEEK), polycarbonate (PC) At least one of the analogs and the like, but the invention is not limited thereto. Hereinafter, the similar numbers in Figures 1 and 2 represent similar elements or portions of similar elements. Referring to Fig. 3, the strain film 12 may be a single film containing at least one material which is deformed in accordance with the change in the concentration of the liquid fuel. In this case, the strain film 12 may be formed of the same material as the first film 12a and have a thickness of from about 1 μm to about 500 μm. However, in order to prevent an electrical short circuit from occurring, the strain gauge 13 may include a waterproof insulating substrate (not shown) 'a metal resistance line (not shown) disposed inside the insulating substrate' and an insulated guiding line (not Graphic). The strain gauge 13 is a device which is disposed on the strained film 12 and which is used to measure the strain of the strained film 12 in accordance with a change in the concentration of the liquid fuel by a change in electrical resistance. 9 200933968 Fig. 4 is an exploded perspective view showing the strain gauge 13 shown in Fig. 1 according to an embodiment of the present invention. A strain system is a deformation that occurs in an object and is defined as the ratio of the stretched or compressed length of the object to the original length when subjected to tensile or compressive forces. That is, the strain system is a term used to represent the deformation measurement of an object initiated by an internal 5 or external force. Referring to Fig. 4, the strain gauge 13 can be one of two types of strain gauges: an electrical strain gauge and a mechanical strain gauge. An electrical strain gauge measures the strain of an object by measuring the change in strain gauge resistance attached to an object in which deformation has occurred. A mechanical strain gauge measures the strain of an object by mechanically measuring a slight change in the distance between the object and the two points after deformation. In the present embodiment, although an electrical strain gauge is used as shown in Fig. 4, the present invention is not limited thereto, and a mechanical strain gauge may be used. Although Fig. 4 shows a single axis meter, the present invention is not limited thereto and an electrical strain gauge such as a two-axis rosette gauge or a three-axis circular flower gauge can also be used. The strain gauge 13 includes a metal resistance wire 13b which is located on or in one of the insulating substrates 13a such as paper or plastic. The metal resistance line 13b is in the form of a coil that connects both ends to the two guiding lines 14. The strain gauge 13 is a sensor for detecting small mechanical strain with an electrical signal. More specifically, if the strain gauge 13 is attached to the surface of the strained film 12, the strain gauge 13 can be oxidized to measure a slight dimensional change, that is, strain, which occurs on the surface of the strained film 12, and is varied from the magnitude of the change. The liquid fuel concentration is obtained. More specifically, the strain gauge 13 is an application in which the strain (deformation) of the length of a resistor device is proportional to the resistance change rate in the resistor device. Moreover, the ratio of the strain of the length to the rate of change of the resistance is called the instrument factor (gauge 200933968 5 ❹ 10 15 Ο 20 factor), which is provided by the strain gauge manufacturer. Therefore, the strain of the length can be calculated from the change in the amount of resistance by the instrument factor. The strain of the length is proportional to the concentration of the liquid fuel, thereby obtaining the liquid fuel concentration from the change in the amount of resistance. The measured strain system is represented by an output k number such as an output voltage or an output current of a bridge circuit, which will be described later. When a tensile force F is applied to the strain gauge 13, the gauge factor, the length change rate ΔL/L, the strain ε, and the resistance change rate Δr/r are expressed by the following equation Κ: Κ = ( Δ R / R /( Δ L / L) = ( Δ R / R ) / ε » That is, Δ R / R = Κ * ε ... (1) The circuit unit 15 is electrically connected to the strain gauge via the guiding line 14 13 converts the resistance change of the strain gauge 13 into an output signal, an output voltage, or an output current. In this embodiment, the circuit unit 15 includes a portion of the Wheatstone bridge and optionally includes an amplifier. The construction and effects of the Wheatstone bridge and amplifier will be detailed later. 5 and 6 are views for explaining the operation of the apparatus 1 for measuring the liquid fuel concentration shown in Fig. 1 according to an embodiment of the present invention. Fig. 5 is a view showing the main body unit 11 and the strain film 12 of the bypass flow path lib partially extracted from the same components as those included in the apparatus 10 for measuring the liquid fuel concentration shown in Fig. 1. And a cross-sectional view of the strain gauge 13. Figure 6 is a diagram for explaining a method for measuring the change in resistance detected by the strain gauge 13 with a change in output voltage. Referring to Figures 5 and 4, when the liquid fuel flows along the main flow path 11a in the direction of the arrow, the liquid fuel partially flows into the first film 12a via the surface of the first sheet 12a. The liquid fuel flow system deforms the first film 12a 11 200933968 so that the second film J attached to the first film 12a in a specific direction 12 is in a phase with the first -1l2af and thus the first thin Strain gauges in the same direction! 3, in the second thin section, 'continued to the first variant 13 of the deformation system resulting in the configuration of the strain gauge: the Chinese:: the rod of the second film (3) of this bending system provides attachment to the second film 12b bends. The resistance of 13b should be changed. , - see the smart resistance circuit, use 2, 6 and 1 ' strain gauge 13 is electrically connected to the circuit unit 15 and constructs I ~ into the four resistors of the Wheatstone bridge & to (10) - electricity (four) 10 15
❹ 對於惠斯登電橋的結構，四個電阻器被對稱性 連接於點_之間，如第6圖所示，—檢流計崎接於點C 與d之間’且—電壓被施加至惠斯登電橋故電流流經電路 =元15且因此在四個電阻抓祝各者中發生-電壓降。 右其間可供檢流計G連接之點e及點d的各電壓變成相等點 c與d之間的電位差變成τ且因此沒有電流流動。因此，檢 流計G的指針指示“〇”。位於四個電阻器心至仏各者的電壓 降係與電阻量成正比。因此，在四個電阻器心至心滿足下 列等式2之條件下惠斯登電橋的輸出電壓為“〇，，。 R，R3=R2*R4 (2) 20 其中Ri代表應變儀電阻，而R2至R4代表假體電阻 (dummy resistance)。 雖然假體電阻R2至R4的電阻值不變，應變儀電阻化根 據應變儀13變形而變動’所以電阻變異係導致輸出電壓Vo 的變化。 12 200933968 輸出電壓Vo、儀因數Κ、應變ε、及輸入電壓Vi之間的 關係如下列等式3表示。亦即，輸出電壓Vo與應變ε成正比。 AVo=l/4*K*c*Vi ......(3) 第6圖所示的惠斯登電橋只是一項被施用至本發明之 5 用於測量液體燃料之設備的範例，且在用於測量液體燃料 之設備中可採用惠斯登電橋的其他修改。 雖然本實施例中只使用一個應變儀13來測量應變薄膜 12的應變，本發明不在此限且可使用一交叉型的兩軸線或 三轴線應變儀來矯正會影響應變薄膜12應變之一溫度變 10 化、移除雜訊、及/或測量在垂直及水平方向中變化之應變。 應變儀13及電路單元15係利用兩導線連接或三導線連 接方法被連接。利用三導線連接方法可能盡量降低根據應 變儀13與電路單元15之間連接電阻之應變的誤差。參照第6 圖，利用兩導線連接方法來連接應變儀13及電路單元15(亦 15 即，惠斯登電橋的一部份）。 因為惠斯登電橋的一輸出電壓Vo產生一很弱的輸出電 壓信號，可利用一放大器（未圖示）來放大輸出電壓Vo。放 大器可譬如為一差異性放大器。 具有上述組態之用於測量液體燃料濃度的設備係可施 20 用至生物科技業、汽車業、燃料電池及類似物。 用於測量液體燃料濃度之設備可用來作為一直接液體 燃料電池，其概括使用諸如曱醇或乙醇等醇作為液體燃 料。使用曱醇的燃料電池稱為直接甲醇燃料電池，其使用 一具有1至2 Μ間濃度之曱醇水性溶液。 13 200933968 燃料電池的效能係根據曱醇濃度變化而變，並必須供 應具有一恆定濃度的甲醇藉以使一直接甲醇燃料電池系統 操作一段長的時間期間。因此，直接曱醇燃料電池系統需 要一用於測量曱醇濃度之設備，其能夠精密地控制曱醇的 5 濃度。 若本發明之用於測量液體燃料濃度的設備施用至直接 甲醇燃料電池，藉由具有簡單結構且具有低製造成本之一 應變薄膜及一應變儀將可能容易且精密地測量甲醇濃度的 變化。 10 雖然已參照本發明的實施例特別地顯示及描述本發 明，一般熟習該技藝者將瞭解可作出形式及細節的不同改 變而不脫離由申請專利範圍所界定之本發明的精神與範 圍。 I：圖式簡單說明3 15 第1圖為顯示根據本發明的一實施例之一用於測量液 體燃料濃度之設備的橫剖視圖； 第2圖為顯示根據本發明的一實施例如第1圖所示之一 應變薄膜及堆疊其上的一應變儀之橫剖視圖； 第3圖為顯示根據本發明另一實施例之一應變薄膜及 20 堆疊其上的一應變儀之橫剖視圖； 第4圖為顯示根據本發明的一實施例之第1圖所示的應 變儀之分解立體圖； 第5及6圖為說明根據本發明的一實施例之第1圖所示 用於測量液體燃料濃度之設備的操作之圖式。 200933968 【主要元件符號說明】 10···用於測量液體燃料濃度之設備 a-d···點 ll···主體部單元 F…拉力 11a···主流通路 G…檢流計 lib···旁通流通路 K…儀因數 11c…溝槽 Rr··應變儀電阻 12…應變薄膜 R2-R4…假體電阻 12a···第一薄膜 Vl···輸入電壓 12b…第二薄膜 Vo…輸出電壓 13…應變儀 △ L/L···長度變化率 13a…絕緣基材 △ R/R…電阻變化率 13b···金屬電阻線路 14…引導線路 15…電路單元 ε…應變 ❹ 15❹ For the structure of the Wheatstone bridge, four resistors are symmetrically connected between the points _, as shown in Figure 6, - the galvanometer is connected between points C and d' and the voltage is applied To the Wheatstone bridge, the current flows through the circuit = element 15 and therefore occurs in the four resistors - the voltage drop. The voltages at the point e and the point d at which the galvanometer G is connected in the right direction become equal points. The potential difference between c and d becomes τ and thus no current flows. Therefore, the pointer of the galvanometer G indicates "〇". The voltage drop across the four resistor cores is proportional to the amount of resistance. Therefore, the output voltage of the Wheatstone bridge is “〇,, R, R3=R2*R4 (2) 20 where the four resistor cores satisfy the following Equation 2, where Ri represents the strain gauge resistance, R2 to R4 represent the dummy resistance. Although the resistance values of the prosthetic resistors R2 to R4 are constant, the strain gauge resistance changes according to the strain gauge 13 deformation, so the resistance variation causes the output voltage Vo to change. 200933968 The relationship between the output voltage Vo, the instrument factor Κ, the strain ε, and the input voltage Vi is expressed by the following Equation 3. That is, the output voltage Vo is proportional to the strain ε. AVo=l/4*K*c*Vi (3) The Wheatstone bridge shown in Fig. 6 is only an example of a device for measuring liquid fuel, which is applied to the present invention, and is used in an apparatus for measuring liquid fuel. Other modifications of the Wheatstone bridge may be employed. Although only one strain gauge 13 is used in this embodiment to measure the strain of the strained film 12, the present invention is not limited thereto and a cross-type two-axis or three-axis strain gauge may be used. To correct the strain film 12 strain, one temperature change, remove noise And/or measuring the strain that varies in the vertical and horizontal directions. The strain gauge 13 and the circuit unit 15 are connected by a two-wire connection or a three-wire connection method. The three-wire connection method may be used to minimize the strain gauge 13 and the circuit unit 15 The error of the strain of the connection resistor. Referring to Figure 6, the two-wire connection method is used to connect the strain gauge 13 and the circuit unit 15 (also part of the Wheatstone bridge). Because of the Wheatstone bridge An output voltage Vo produces a weak output voltage signal, and an amplifier (not shown) can be used to amplify the output voltage Vo. The amplifier can be, for example, a differential amplifier. The above configuration is used to measure the concentration of the liquid fuel. The equipment can be used in the biotechnology industry, the automotive industry, fuel cells and the like. The equipment for measuring the concentration of liquid fuel can be used as a direct liquid fuel cell, which generally uses an alcohol such as methanol or ethanol as a liquid fuel. A fuel cell using sterol is called a direct methanol fuel cell, which uses an aqueous solution of sterol having a concentration of 1 to 2 Torr. 13 200 933968 The performance of a fuel cell varies according to the concentration of sterol and must be supplied with a constant concentration of methanol to allow a direct methanol fuel cell system to operate for a long period of time. Therefore, a direct sterol fuel cell system requires one for An apparatus for measuring a concentration of sterol capable of precisely controlling the concentration of sterol 5. If the apparatus for measuring the concentration of a liquid fuel of the present invention is applied to a direct methanol fuel cell, it has a simple structure and has a strain of one of low manufacturing costs. The film and a strain gauge will make it possible to measure the change in methanol concentration easily and precisely. 10 While the invention has been particularly shown and described with respect to the embodiments of the invention, those skilled in the art will understand that various changes in form and detail can be made. The spirit and scope of the invention as defined by the scope of the claims is not departed. I: BRIEF DESCRIPTION OF THE DRAWINGS 3 15 FIG. 1 is a cross-sectional view showing an apparatus for measuring a liquid fuel concentration according to an embodiment of the present invention; and FIG. 2 is a view showing an embodiment according to the present invention, for example, FIG. A cross-sectional view showing a strain gauge and a strain gauge stacked thereon; FIG. 3 is a cross-sectional view showing a strain gauge and a strain gauge stacked thereon according to another embodiment of the present invention; An exploded perspective view showing a strain gauge according to Fig. 1 according to an embodiment of the present invention; and Figs. 5 and 6 are diagrams showing an apparatus for measuring a liquid fuel concentration shown in Fig. 1 according to an embodiment of the present invention. The schema of the operation. 200933968 [Description of main component symbols] 10···Device for measuring liquid fuel concentration ad···Point ll··· Main unit F... Pulling force 11a···Mainstream passage G... galvanometer lib··· Flow path K... instrument factor 11c... groove Rr·· strain gauge resistor 12... strain film R2-R4...prosthesis resistor 12a···first film V1···input voltage 12b...second film Vo...output voltage 13... strain gauge △ L / L · · length change rate 13a ... insulation substrate △ R / R ... resistance change rate 13b · · metal resistance line 14 ... guide line 15 ... circuit unit ε ... strain ❹ 15