JP2004301596A - Load measuring device and load measuring method - Google Patents

Load measuring device and load measuring method Download PDF

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JP2004301596A
JP2004301596A JP2003093467A JP2003093467A JP2004301596A JP 2004301596 A JP2004301596 A JP 2004301596A JP 2003093467 A JP2003093467 A JP 2003093467A JP 2003093467 A JP2003093467 A JP 2003093467A JP 2004301596 A JP2004301596 A JP 2004301596A
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load
value
linear
measuring device
linear member
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JP3723853B2 (en
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Jiyunichi Akizono
純一 秋園
Joji Hirabayashi
丈嗣 平林
Makoto Uchiumi
真 内海
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National Institute of Maritime Port and Aviation Technology
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a load measuring device and a load measuring method capable of measuring accurately a wide-range load from a light load to a heavy load by one device. <P>SOLUTION: This device is equipped with an approximately U-shaped external force response body formed by arranging two linear members 11A, 12A comprising copper or the like mutually in parallel across the first gap 19A and joining each end by a joining member. In the device, a projection part 16A is projected from the periphery of the first end 14A of the second linear member 12A, and the second gap 20A is provided between the first working part 17A near the tip and the second working part 18A, and a strain gage 80 is stuck on the surface of the external force response body 10A. When a compressive load P is lighter than the first load value, deformation is carried out, wherein the first working part 17A and the second working part 18A are drawn close each other, and when the load is heavier than the first load value, deformation is carried out, wherein the first working part 17A and the second working part 18A are brought into contact each other and then the approximate center of the second linear member 12A and the first linear member 11A are drawn close each other, and the value of the load is measured from an output from the strain gage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、荷重測定装置及び荷重測定方法に係り、特に、小荷重から大荷重まで広い範囲の値の荷重の測定が可能な荷重測定装置及び荷重測定方法に関するものである。
【０００２】
【従来の技術】
従来、構造物等に作用する荷重を測定する装置としては、ロードセル（例えば、特許文献１参照）などが用いられていた。ロードセル（図示せず）は、鋼等の弾性体からなる力検出部材に歪みゲージが貼り付けられて構成されている。ロードセルで荷重を測定する場合には、力検出部材に荷重を作用させ、荷重により力検出部材が変形して生じた歪みの変化を、歪みゲージの電気抵抗値の変化として測定する。
【０００３】
次に、歪みゲージについて説明する。図１２に示すように、歪みゲージ８０は、ゲージベース８１と、抵抗部８２と、リード線８３及び８４を有して構成されている。ゲージベース８１は、紙、ポリエステル樹脂等の電気絶縁材料からなり、薄膜状に形成されている。抵抗部８２は、金属や半導体等からなり、線状又は箔状に形成されている。抵抗部８２の長さＬＧはゲージ長と呼ばれる。歪みゲージ８０は、接着剤等により被測定物の表面に貼り付けて使用される。
【０００４】
被測定物に外力が加わると、歪みゲージ８０の貼り付け位置である被測定物の表面に応力が発生し、これに伴って抵抗部８２のゲージ長ＬＧに伸び又は縮み量ΔＬが発生する。ΔＬとＬＧの比（ΔＬ／ＬＧ）を「歪み」といい、被測定物の表面に発生する「表面歪み」と等しい。金属等の抵抗は、歪みに比例して変化する。歪みゲージ８０の抵抗値をＲとし、歪みをε（＝ΔＬ／ＬＧ）とし、歪みεによる歪みゲージ８０の抵抗値の変化をΔＲとすると、下式（１）の関係が成立する。
ΔＲ／Ｒ＝Ｋ×ε ………（１）
ここに、Ｋは、比例定数であり、ゲージ率と呼ばれる。
【０００５】
また、歪みεと応力σ（荷重を作用面積で除した単位面積当たりの力。単位：Ｐａ パスカル。）との間には、下式（２）の関係が成立する。
σ＝Ｅ×ε ………（２）
ここに、Ｅ（単位：Ｐａ パスカル）は、比例定数であり、弾性係数又はヤング率と呼ばれる。
【０００６】
また、歪みゲージ８０におけるリード線８３及び８４は、金属等の導体で形成され、外部の電気回路等との接続に用いられ、上記した歪みゲージ８０の抵抗値変化を電圧値等の変化として外部に出力する。
【０００７】
なお、上記した歪みゲージ８０を４本用いて菱形状に接続し、いわゆる「ホイートストンブリッジ回路」を構成すれば、温度変化の影響の補償や、誤差の消去を行うことができる。
【０００８】
【特許文献１】
特開平７−２０９１０２号公報（第１−１２頁、図１−１４）
【０００９】
【発明が解決しようとする課題】
しかし、上記した従来のロードセルのような荷重測定装置においては、力検出部材を構成する弾性体は、荷重の増大につれて以下の挙動を示す。まず、図１３に示すように、応力が第１の値σｐ（以下、「比例限界応力」という）に達すると、上式（２）に示す歪みεと応力σの比例関係が終了し、その後は歪みεと応力σの関係が直線ではなく曲線状となる。その後さらに荷重を増すと応力が増大し、応力が第２の値σＥ（以下、「弾性限界応力」という）に達した後は、弾性体に生じた歪みは、荷重を除いても零に戻らず残留する。その後、荷重の増大につれて、応力は第３の値σｙ（以下、「降伏点応力」という）に達し、これ以降は歪みが増大し始め、最終的には破断（図１３の点Ｚを参照）に至る。
【００１０】
したがって、小荷重を精度良く計測できる力検出部材の弾性限界応力は小さいため、大荷重を作用させると、弾性限界を越え、極端な場合には力検出部材が破壊する、という問題があった。また、大荷重を計測できる力検出部材の弾性限界応力は大きいが、小荷重を作用させた場合には、発生する歪み値が小さすぎることとなり、測定値が誤差（ノイズ）に埋もれてしまい、精度良い測定が非常に困難となる、という問題があった。したがって、従来の荷重測定装置では、小荷重から大荷重までの広い範囲の値の荷重の精度良い測定を１台の装置で行うことは実際上できなかった。
【００１１】
本発明は、上記の問題を解決するためになされたものであり、本発明の解決しようとする課題は、小荷重から大荷重までの広い範囲の値の荷重の精度良い測定が１台の装置で可能な荷重測定装置、及び荷重測定方法を提供することにある。
【００１２】
【課題を解決するための手段】
上記課題を解決するため、請求項１に記載した荷重測定装置は、
弾性体からなり、一端で固定され他端が自由状態の梁状部材の略中央に荷重が載荷されるようにし、前記自由端の下方又は上方に不動部を設け、当該不動部と前記自由端との間に構造変換用間隙を設けて外力応答体を構成し、前記外力応答体の前記固定端付近の表面に歪みゲージを貼付し、
前記荷重が第１荷重値未満の場合には前記自由端が前記不動部に接近するように変形し、前記荷重が前記第１荷重値と等しくなった場合には前記自由端が前記不動部に接触し、前記荷重が前記第１荷重値を越えた場合には前記自由端が前記不動部に接触した状態で前記梁状部材の略中央が前記不動部に接近するように変形するように構成し、前記歪みゲージの出力から前記荷重の値を測定すること
を特徴とする。
【００１３】
また、請求項２に記載した荷重測定装置は、
弾性体からなり、直線棒状に形成されたＮ（Ｎ：２以上の整数）個の直線部材を互いに平行に第１間隙を配して配置し前記Ｎ個の直線部材のうち同じ側で隣接する２個の端部どうしを（Ｎ−１）個の接合部材で交互に接合して構成される略Ｕ字状又は略Ｓ字状若しくは略波形状の外力応答体を備え、
前記直線部材のうち最も外側となる直線部材である最外直線部材を前記梁状部材としその内面の先端となる第１端の付近から前記第１端に対向する他の直線部材の端である第２端の付近へ向けて、又は前記第２端の付近から前記第１端の付近へ向けて、それぞれ突出部が突設されるとともに、前記突出部の先端付近に設けられる第１作用部と、前記第２端又は前記第１端の付近で前記第１作用部に対向する箇所に設けられる第２作用部との間に、前記構造変換用間隙として第２間隙が設けられ、
前記外力応答体の表面に歪みゲージが貼付され、
前記最外直線部材の外面の略中央の各々に同一軸上となり方向が逆となる荷重を作用させ、前記荷重が第１荷重値未満の場合には前記第１作用部と前記第２作用部が互いに接近するように変形し、前記荷重が前記第１荷重値と等しくなった場合には前記第１作用部と前記第２作用部が互いに接触し、前記荷重が前記第１荷重値を越えた場合には前記第１作用部が前記第２作用部に接触した状態で前記最外直線部材の略中央と、隣接する直線部材が互いに接近するように変形するように構成し、前記歪みゲージの出力から前記荷重の値を測定すること
を特徴とする。
【００１４】
また、請求項３に記載した荷重測定装置は、請求項１記載の荷重測定装置において、
前記荷重は圧縮荷重であり、前記荷重が前記第１荷重値未満の場合には、前記最外直線部材と、隣接する直線部材が互いに接近するように変形すること
を特徴とする。
【００１５】
また、請求項４に記載した荷重測定装置は、請求項１記載の荷重測定装置において、
前記荷重は引張荷重であり、前記荷重が前記第１荷重値未満の場合には、前記最外直線部材と、隣接する直線部材は互いに離れるように変形すること
を特徴とする。
【００１６】
また、請求項５に記載した荷重測定装置は、請求項４記載の荷重測定装置において、
前記突出部は略Ｌ字状に構成され、前記第１作用部は、前記略Ｌ字状の突出部の屈曲端部であり、
前記第２作用部は、前記第１作用部によって係止可能に設置された被係止部であること
を特徴とする。
【００１７】
また、請求項６に記載した荷重測定装置は、請求項１記載の荷重測定装置において、
前記歪みゲージは、
前記最外直線部材と、前記最外直線部材に隣接する直線部材を接合する接合部材である最外接合部材の表面に貼付されること
を特徴とする。
【００１８】
また、請求項７に記載した荷重測定方法は、
弾性体からなり、一端で固定され他端が自由状態の梁状部材の略中央に荷重が載荷されるようにし、前記自由端の下方又は上方に不動部を設け、当該不動部と前記自由端との間に構造変換用間隙を設けて外力応答体を構成し、前記外力応答体の前記固定端付近の表面に歪みゲージを貼付し、
前記荷重が第１荷重値未満の場合には前記自由端が前記不動部に接近するように変形し、前記荷重が前記第１荷重値と等しくなった場合には前記自由端が前記不動部に接触し、前記荷重が前記第１荷重値を越えた場合には前記自由端が前記不動部に接触した状態で前記梁状部材の略中央が前記不動部に接近するように変形するように構成し、前記歪みゲージの出力から前記荷重の値を測定すること
を特徴とする。
【００１９】
また、請求項８に記載した荷重測定方法は、
弾性体からなり、直線棒状に形成されたＮ（Ｎ：２以上の整数）個の直線部材を互いに平行に第１間隙を配して配置し前記Ｎ個の直線部材のうち同じ側で隣接する２個の端部どうしを（Ｎ−１）個の接合部材で交互に接合して構成される略Ｕ字状又は略Ｓ字状若しくは略波形状の外力応答体を用い、
前記直線部材のうち最も外側となる直線部材である最外直線部材を前記梁状部材としその内面の先端となる第１端の付近から前記第１端に対向する他の直線部材の端である第２端の付近へ向けて、又は前記第２端の付近から前記第１端の付近へ向けて、それぞれ突出部が突設されるとともに、前記突出部の先端付近に設けられる第１作用部と、前記第２端又は前記第１端の付近で前記第１作用部に対向する箇所に設けられる第２作用部との間に、前記構造変換用間隙として第２間隙が設けられ、
前記外力応答体の表面に歪みゲージが貼付され、
前記最外直線部材の外面の略中央の各々に同一軸上となり方向が逆となる荷重を作用させ、前記荷重が第１荷重値未満の場合には前記第１作用部と前記第２作用部が互いに接近するように変形し、前記荷重が前記第１荷重値と等しくなった場合には前記第１作用部と前記第２作用部が互いに接触し、前記荷重が前記第１荷重値を越えた場合には前記第１作用部が前記第２作用部に接触した状態で前記最外直線部材の略中央と、隣接する直線部材が互いに接近するように変形するように構成し、前記歪みゲージの出力から前記荷重の値を測定すること
を特徴とする。
【００２０】
【発明の実施の形態】
以下、本発明の実施形態について、図面を参照しながら説明する。
【００２１】
（１）第１実施形態
図１は、本発明の第１実施形態である荷重測定装置の構成を示す図である。図１に示すように、この荷重測定装置１Ａは、第１直線部材１１Ａと、第２直線部材１２Ａと、接合部材１３Ａと、歪みゲージ８０と、載荷用スピンドル２３Ａ及び２４Ａを備えて構成されている。
【００２２】
第１直線部材１１Ａは、鋼等の弾性体からなり、直線棒状に形成されている。また、第２直線部材１２Ａは、鋼等の弾性体からなり、直線棒状に形成されている。第１直線部材１１Ａと第２直線部材１２Ａは、互いに平行となるように配置され、両者の間には第１間隙１９Ａが配設されている。
【００２３】
また、第１直線部材１１Ａと第２直線部材１２Ａのうち、同じ側で隣接する２個の端部どうし、図１における第１直線部材１１Ａの左側の端部と、第２直線部材１２Ａの左側の端部は、接合部材１３Ａによって接合されている。接合部材１３Ａは、鋼等の弾性体からなり、弧状に形成されている。ここに、第１直線部材１１Ａと、第２直線部材１２Ａと、接合部材１３Ａは、全体が略Ｕ字状となる外力応答体１０Ａを構成している。
【００２４】
第２直線部材１２Ａの内面の先端となる第１端１４Ａの付近からは、第１端１４Ａに対向する直線部材である第１直線部材１１Ａの端である第２端１５Ａの付近へ向けて、突出部１６Ａが突設されている。図１の場合、第２直線部材１２Ａは、特許請求の範囲における最外直線部材及び梁状部材に相当している。
【００２５】
また、突出部１６Ａの先端付近の面１７Ａは、第１作用部を構成している。また、第２端１５Ａの付近で第１作用部１７Ａに対向する箇所の面１８Ａは、第２作用部を構成している。第１作用部１７Ａと第２作用部１８Ａとの間には、第２間隙２０Ａが配設されている。この第２間隙２０Ａは、特許請求の範囲における構造変換用間隙に相当している。
【００２６】
また、接合部材１３Ａの外面には、歪みゲージ８０が貼付されている。この場合には、接合部材１３Ａは、特許請求の範囲における最外接合部材に相当している。歪みゲージ８０は、上記の従来例における歪みゲージと同一の構成及び作用を有している。
【００２７】
また、第１直線部材１１Ａの外面の略中央には、雌ネジ孔２１Ａが形成され、この雌ネジ孔２１Ａに、載荷用スピンドル２３Ａの外周の雄ネジが螺合するようになっている。また、第２直線部材１２Ａの外面の略中央には、雌ネジ孔２２Ａが形成され、この雌ネジ孔２２Ａに、載荷用スピンドル２４Ａの外周の雄ネジが螺合するようになっている。このような構成により、載荷用スピンドル２３Ａが雌ネジ孔２１Ａにねじ込まれて取り付けられ、載荷用スピンドル２４Ａが雌ネジ孔２２Ａにねじ込まれて取り付けられる。
【００２８】
次に、上記した構成の荷重測定装置１Ａを用いて荷重を測定する方法について、図１及び図２及び図３を用いて説明する。
【００２９】
まず、載荷用スピンドル２３Ａ、２４Ａの各々に、同一軸上となり方向が逆となる荷重、例えば図１ないし図３に示す圧縮荷重Ｐを作用させる。
【００３０】
この場合、圧縮荷重Ｐが小さく、圧縮荷重がある値（以下、「第１荷重値」という。）未満の値であるうちは、圧縮荷重Ｐを増加させていくと、図１に示すように、第１作用部１７Ａと第２作用部１８Ａが互いに接近するように変形する。また、この場合、最外直線部材である第２直線部材１２Ａと、隣接する直線部材である第１直線部材１１Ａが互いに接近するように変形する。
【００３１】
その後、圧縮荷重Ｐをさらに増加させていくと、圧縮荷重Ｐが第１荷重値となったときに、変形量が第２間隙２０Ａの値と等しくなる。このため、図２に示すように、第１作用部１７Ａと第２作用部１８Ａが互いに接触する。
【００３２】
さらにその後、圧縮荷重Ｐを第１荷重値を越えてさらに増加させていくと、図３に示すように、第１作用部１７Ａが第２作用部１８Ａに接触した状態を保ちつつ、第２直線部材１２Ａの略中央と、隣接する第１直線部材１１Ａが互いに接近するように変形する。
【００３３】
この際、歪みゲージ８０は、上記したホイートストンブリッジ回路等（図示せず）を構成しており、電源（図示せず）が接続されるとともに出力端（図示せず）が電圧計（図示せず）に接続され、歪みに対応した電圧が計測される。この電圧の変化から、歪みが算出される。
【００３４】
外力応答体１０Ａの構造は図１ないし図３のように既知であるから、あらかじめ数値計算によって、圧縮荷重Ｐと歪みとの関係を求めることができる。あるいは、値のわかっている荷重を載荷し、この場合の歪みを測定する予備試験を行ってもよい。これにより、歪みゲージ８０からの出力のみによって、圧縮荷重Ｐを測定することが可能となる。
【００３５】
次に、第１実施形態の荷重測定装置１Ａの作用原理を、図４を参照しながら説明する。
【００３６】
図１ないし図３に示す荷重測定装置１Ａにおける外力応答体１０Ａは、図１ないし図３の左端の接合部材１３Ａの略中央で切断すれば、２つの梁状部材となることがわかる。このことから、図１の状態（第１作用部１７Ａと第２作用部１８Ａが互いに接触していない状態）の構造力学的モデルは、図４（Ａ）に示すような、いわゆる「片持ち梁」が２個、鏡対称状態で接続している、と考えることができる。すなわち、図１における第１直線部材１１Ａは、左端で固定され、右端が自由状態となっている梁の略中央に荷重Ｐが作用するような構造力学的モデル（以下、「第１構造モデル」という。）と略等価である、と考えられる。同様にして、第２直線部材１２Ａも、左端で固定され、右端が自由状態となっている梁の略中央点Ｃに荷重Ｐが作用するような構造力学的モデル（以下、「第１構造モデル」という。）と略等価である、と考えられる。
【００３７】
この場合、図４（Ａ）の片持ち梁ＡＢの固定端Ａにおける曲げモーメントＭＡ１は、荷重をＰとし載荷位置を梁の略中央とし固定端からの距離をａとすれば、ＭＡ１＝Ｐ×ａ（単位：Ｎｍ）となる。
【００３８】
これに対し、図２及び図３の状態（第１作用部１７Ａと第２作用部１８Ａが互いに接触した後の状態）の構造力学的モデルは、図４（Ｂ）に示すような、左端が固定され、右端が単純支持された梁が２個、鏡対称状態で接続している、と考えることができる。すなわち、図２及び図３における第１直線部材１１Ａは、左端で固定され、右端が単純支持状態となっている梁の略中央点Ｃ´に荷重Ｐが作用するような構造力学的モデル（以下、「第２構造モデル」という。）と略等価である、と考えられる。同様にして、第２直線部材１２Ａも、左端で固定され、右端が単純支持状態となっている梁の略中央点Ｃ´に荷重Ｐが作用するような構造力学的モデル（以下、「第２構造モデル」という。）と略等価である、と考えられる。
【００３９】
この場合、図４（Ｂ）の「半固定・半単純支持梁」Ａ´Ｂ´の固定端Ａ´における曲げモーメントＭＡ２は、荷重をＰとし載荷位置を梁の略中央とし固定端からの距離をａとすれば、ＭＡ２＝３×Ｐ×ａ／８＝０．３７５×Ｐ×ａ（単位：Ｎｍ）となる。すなわち、この場合の固定端モーメントＭＡ２は、上記したＭＡ１の約０．４倍となっている。
【００４０】
このことから明らかなように、この荷重測定装置１Ａの外力応答体１０Ａは、第１作用部１７Ａと第２作用部１８Ａが互いに接触する前の段階と、接触後の段階では、構造力学的モデルが異なるものへ変換され、それに伴い、固定端（図１ないし図３における図の左端）の曲げモーメントが接触前の４０％以下に減少するようになっている。歪みの値は、曲げモーメントの値に比例する。したがって、この荷重測定装置１Ａの歪みゲージ８０からの出力は、第１作用部１７Ａと第２作用部１８Ａが互いに接触する前と後とでは、出力値が約６０％減少することになる。これは、この荷重測定装置１Ａでは、圧縮荷重Ｐの値が第１荷重値に達すると、それ以上の荷重では、歪みを測定する「感度」が０．４倍に下がる、ということを意味している。
【００４１】
このような原理により、本実施形態の荷重測定装置１Ａにおける外力応答体１０Ａの構造は、一端で固定され他端が自由状態の梁の略中央に荷重が載荷される第１構造モデルにおいて、自由端の下方又は上方に不動部を設け、この不動部と自由端との間に第２間隙２０Ａを設けた機構と略等価である。このため、荷重がある荷重値（第１荷重値）以上となると、自由端の変形量が第２間隙２０Ａの値と等しくなり、自由端が不動部に接触する。したがって、荷重が第１荷重値以上の場合には、外力応答体１０Ａの構造系が、一端で固定され他端が単純支持の梁の略中央に荷重が載荷される第２構造モデルに変換される。この場合、構造変換後の構造系の方が、固定端Ａ´付近の曲げモーメント及び歪みが、構造変換前の構造系のときよりも小さい。このため、歪み測定の感度を下げることができ、小荷重から大荷重まで、広いダイナミック・レンジで荷重測定を行うことができる、という利点を有している。なお、図４（Ａ）の梁構造モデルにおいて、梁ＡＢの自由端Ｂのたわみが第１間隙２０Ａの値と等しくなるときの荷重Ｐが、構造モデルが第２構造モデルに変換するときの荷重Ｐとなる。また、図４（Ｂ）の第２構造モデルにおいて、測定できる荷重Ｐの最大値は、荷重Ｐによる応力が梁Ａ´Ｂ´の強度以下であるとすると、梁Ａ´Ｂ´の中央点Ｃ´のたわみが第１間隙１９Ａの値と等しくなり、梁の中央点Ｃ´の下面が下方の不動部の床に接触するときの荷重となる。
【００４２】
なお、上記した突出部１６Ａのかわりに、第１直線部材１１Ａの内面の先端である第２端１５Ａの付近から、第２端１５Ａに対向する直線部材である第２直線部材１２Ａの端である第１端１４Ａの付近へ向けて突設される突出部（図示せず）を設けてもよい。この場合には、第１直線部材１１Ａは、特許請求の範囲における最外直線部材及び梁状部材に相当している。
【００４３】
この場合には、第２端１５Ａから突設される他の突出部の先端付近の面が、他の第１作用部となる。また、第１端１４Ａの付近で、前記の他の第１作用部に対向する箇所の面が、他の第２作用部となる。また、他の第１作用部と他の第２作用部との間に配される間隙が、第２間隙となる。
【００４４】
（２）第２実施形態
本発明は、上記した第１実施形態以外の他の構成によっても、実現可能である。図５は、本発明の第２実施形態である荷重測定装置の構成を示す図である。また、図６は、第２実施形態の荷重測定装置において載荷により第１作用部と第２作用部が互いに接触した状態を示す図である。
【００４５】
図５に示すように、この荷重測定装置１Ｂは、第１直線部材１１Ｂと、第２直線部材１２Ｂと、接合部材１３Ｂと、歪みゲージ８０と、載荷用スピンドル２３Ｂ及び２４Ｂを備えて構成されている。図１ないし図３の第１実施形態１Ａと、図５及び図６の第２実施形態１Ｂは、第１直線部材と第２直線部材、及び載荷用スピンドルの上下関係が逆になっている。
【００４６】
第１直線部材１１Ｂは、鋼等の弾性体からなり、直線棒状に形成されている。また、第２直線部材１２Ｂは、鋼等の弾性体からなり、直線棒状に形成されている。第１直線部材１１Ｂと第２直線部材１２Ｂは、互いに平行となるように配置され、両者の間には第１間隙１９Ｂが配設されている。
【００４７】
また、第１直線部材１１Ｂと第２直線部材１２Ｂのうち、同じ側で隣接する２個の端部どうし、図５における第１直線部材１１Ｂの左側の端部と、第２直線部材１２Ｂの左側の端部は、接合部材１３Ｂによって接合されている。接合部材１３Ｂは、鋼等の弾性体からなり、弧状に形成されている。ここに、第１直線部材１１Ｂと、第２直線部材１２Ｂと、接合部材１３Ｂは、全体が略Ｕ字状となる外力応答体１０Ｂを構成している。
【００４８】
第２直線部材１２Ｂの内面の先端となる第１端１４Ｂの付近からは、第１端１４Ｂに対向する直線部材である第１直線部材１１Ｂの端である第２端１５Ｂの付近へ向けて、突出部１６Ｂが突設されている。この突出部１６Ｂは、略Ｌ字状に構成されている。図５の場合、第２直線部材１２Ｂは、特許請求の範囲における最外直線部材及び梁状部材に相当している。
【００４９】
また、略Ｌ字状の突出部１６Ｂの先端付近は、第１直線部材１１Ｂの下部へ回り込むように図５の左側へ向けて略直角に屈曲した屈曲端部１７Ｂとなっており、この屈曲端部１７Ｂは、第１作用部を構成している。また、第２端１５Ｂの付近で第１作用部１７Ｂに対向する箇所の面１８Ｂは、第２作用部を構成している。第２作用部１８Ｂは、第１作用部１７Ｂによって係止可能であり、第２作用部１８Ｂは、第１作用部１７Ｂに対して被係止部となっている。第１作用部１７Ｂと第２作用部１８Ｂとの間には、第２間隙２０Ｂが配設されている。この第２間隙２０Ｂは、特許請求の範囲における構造変換用間隙に相当している。
【００５０】
また、接合部材１３Ｂの外面には、歪みゲージ８０が貼付されている。この場合には、接合部材１３Ｂは、特許請求の範囲における最外接合部材に相当している。歪みゲージ８０は、上記の従来例における歪みゲージと同一の構成及び作用を有している。
【００５１】
また、第１直線部材１１Ｂの外面の略中央には、雌ネジ孔２１Ｂが形成され、この雌ネジ孔２１Ｂに、載荷用スピンドル２３Ｂの外周の雄ネジが螺合するようになっている。また、第２直線部材１２Ｂの外面の略中央には、雌ネジ孔２２Ｂが形成され、この雌ネジ孔２２Ｂに、載荷用スピンドル２４Ｂの外周の雄ネジが螺合するようになっている。このような構成により、載荷用スピンドル２３Ｂが雌ネジ孔２１Ｂにねじ込まれて取り付けられ、載荷用スピンドル２４Ｂが雌ネジ孔２２Ｂにねじ込まれて取り付けられる。
【００５２】
次に、上記した構成の荷重測定装置１Ｂを用いて荷重を測定する方法について、図５及び図６を用いて説明する。
【００５３】
まず、載荷用スピンドル２３Ｂ、２４Ｂの各々に、同一軸上となり方向が逆となる荷重、例えば図５及び図６に示す引張荷重Ｔを作用させる。
【００５４】
この場合、引張荷重Ｔが小さく、圧縮荷重がある値（以下、「第１荷重値」という。）未満の値であるうちは、引張荷重Ｔを増加させていくと、図５に示すように、第１作用部１７Ｂと第２作用部１８Ｂが互いに接近するように変形する。また、この場合、最外直線部材である第２直線部材１２Ｂと、隣接する直線部材である第１直線部材１１Ｂは互いに離れるように変形する。
【００５５】
その後、圧縮荷重Ｐをさらに増加させていくと、引張荷重Ｔが第１荷重値となったときに、変形量が第２間隙２０Ｂの値と等しくなる。このため、図２に示すように、第１作用部１７Ｂと第２作用部１８Ｂが互いに接触する。
【００５６】
さらにその後、引張荷重Ｔを第１荷重値を越えてさらに増加させていくと、図示はしていないが、第１作用部１７Ｂと第２作用部１８Ｂが互いに接触した状態を保ちつつ、第２直線部材１２Ｂの略中央と、隣接する第１直線部材１１Ｂは互いに離れるように変形する。
【００５７】
この際、歪みゲージ８０は、上記したホイートストンブリッジ回路等（図示せず）を構成しており、電源（図示せず）が接続されるとともに出力端（図示せず）が電圧計（図示せず）に接続され、歪みに対応した電圧が計測される。この電圧の変化から、歪みが算出される。
【００５８】
外力応答体１０Ｂの構造は図５及び図６のように既知であるから、あらかじめ数値計算によって、引張荷重Ｔと歪みとの関係を求めることができる。あるいは、値のわかっている荷重を載荷し、この場合の歪みを測定する予備試験を行ってもよい。これにより、歪みゲージ８０からの出力のみによって、引張荷重Ｔを測定することが可能となる。
【００５９】
第２実施形態の荷重測定装置１Ｂの作用原理は、図４における荷重Ｐのかわりに、逆向き（上向き）の荷重Ｔが梁の略中央に作用するような構造力学的モデルと略等価である。したがって、曲げモーメントや歪みは、正負の符号が逆となるだけで、絶対値では、同じ挙動を示す。
【００６０】
すなわち、図５及び図６に示す荷重測定装置１Ｂにおける外力応答体１０Ｂは、図５及び図６の左端の接合部材１３Ｂの略中央で切断すれば、２つの梁状部材となることがわかる。このことから、図５の状態（第１作用部１７Ｂと第２作用部１８Ｂが互いに接触していない状態）の構造力学的モデルは、図４（Ｂ）に示すような、いわゆる「片持ち梁」が２個、鏡対称状態で接続している、と考えることができる。すなわち、図５における第１直線部材１１Ｂは、左端で固定され、右端が自由状態となっている梁の略中央に荷重Ｐとは逆方向の荷重Ｔ（図示せず）が作用するような構造力学的モデル（以下、「第１構造モデル」という。）と略等価である、と考えられる。同様にして、第２直線部材１２Ｂも、左端で固定され、右端が自由状態となっている梁の略中央に荷重Ｔ（図示せず）が作用するような構造力学的モデル（以下、「第１構造モデル」という。）と略等価である、と考えられる。
【００６１】
この場合、図４（Ｂ）の片持ち梁ＡＢの固定端の曲げモーメントＭＡ１は、荷重をＴとし載荷位置を梁の略中央とし固定端からの距離をａとすれば、ＭＡ１＝−Ｔ×ａ（単位：Ｎｍ）となる。
【００６２】
これに対し、図６の状態（第１作用部１７Ｂと第２作用部１８Ｂが互いに接触した後の状態）の構造力学的モデルは、図４（Ｂ）に示すような、左端が固定され、右端が単純支持された梁が２個、鏡対称状態で接続している、と考えることができる。すなわち、図６における第１直線部材１１Ｂは、左端で固定され、右端が単純支持状態（支点の不動部は支点の上方となり、図４（Ｂ）とは逆になる。）となっている梁の略中央に荷重Ｐとは逆方向の荷重Ｔ（図示せず）が作用するような構造力学的モデル（以下、「第２構造モデル」という。）と略等価である、と考えられる。同様にして、第２直線部材１２Ｂも、左端で固定され、右端が単純支持状態（支点の不動部は支点の上方となり、図４（Ｂ）とは逆になる。）となっている梁の略中央に荷重Ｔ（図示せず）が作用するような構造力学的モデル（以下、「第２構造モデル」という。）と略等価である、と考えられる。
【００６３】
この場合、図４（Ｂ）の「半固定・半単純支持梁」Ｂ´Ｂ´の固定端の曲げモーメントＭＡ２は、荷重をＴとし載荷位置を梁の略中央とし固定端からの距離をａとすれば、ＭＡ２＝−３×Ｔ×ａ／８＝−０．３７５×Ｔ×ａ（単位：Ｎｍ）となる。すなわち、この場合の固定端モーメントＭＡ２は、上記したＭＡ１の約０．４倍となっている。
【００６４】
このことから明らかなように、この荷重測定装置１Ｂの外力応答体１０Ｂは、第１作用部１７Ｂと第２作用部１８Ｂが互いに接触する前の段階と、接触後の段階では、構造力学的モデルが異なるものへ変換され、それに伴い、固定端（図５及び図６における図の左端）の曲げモーメントが接触前の４０％以下に減少するようになっている。歪みの値は、曲げモーメントの値に比例する。したがって、この荷重測定装置１Ｂの歪みゲージ８０からの出力は、第１作用部１７Ｂと第２作用部１８Ｂが互いに接触する前と後とでは、出力値が約６０％減少することになる。これは、この荷重測定装置１Ｂでは、引張荷重Ｔの値が第１荷重値に達すると、それ以上の荷重では、歪みを測定する「感度」が０．４倍に下がる、ということを意味している。
【００６５】
このような原理により、本実施形態の荷重測定装置１Ｂにおける外力応答体１０Ｂの構造は、一端で固定され他端が自由状態の梁の略中央に荷重が載荷される第１構造モデルにおいて、自由端の上方に不動部を設け、この不動部と自由端との間に第２間隙２０Ｂを設けた機構と略等価である。このため、荷重がある荷重値（第１荷重値）以上となると、自由端の変形量が第２間隙２０Ｂの値と等しくなり、自由端が上方の不動部に接触する。したがって、荷重が第１荷重値以上の場合には、外力応答体１０Ｂの構造系が、一端で固定され他端が単純支持の梁の略中央に荷重が載荷される第２構造モデルに変換される。この場合、構造変換後の構造系の方が、固定端付近の曲げモーメント及び歪みが、構造変換前の構造系のときよりも小さい。このため、歪み測定の感度を下げることができ、小荷重から大荷重まで、広いダイナミック・レンジで荷重測定を行うことができる、という利点を有している。なお、図４（Ａ）の梁構造モデルにおいて、梁ＡＢの自由端Ｂのたわみが第１間隙２０Ｂの値と等しくなるときの荷重Ｐが、構造モデルが第２構造モデルに変換するときの荷重Ｐとなる。また、上記した第２構造モデルにおいて、測定できる荷重Ｔの最大値は、荷重Ｔによる応力が梁の強度以下であるとすると、梁Ａ´Ｂ´の中央点Ｃ´のたわみが第１間隙１９Ｂの値と等しくなり、梁の中央点の上面が上方の不動部の天井に接触するときの荷重となる。
【００６６】
なお、上記した突出部１６Ｂのかわりに、第１直線部材１１Ｂの内面の先端である第２端１５Ｂの付近から、第２端１５Ｂに対向する直線部材である第２直線部材１２Ｂの端である第１端１４Ｂの付近へ向けて突設される略Ｌ字状の突出部（図示せず）を設けてもよい。この場合には、第１直線部材１１Ｂは、特許請求の範囲における最外直線部材及び梁状部材に相当している。
【００６７】
この場合には、第２端１５Ｂから突設される略Ｌ字状の他の突出部の先端付近から屈曲する屈曲端部が、他の第１作用部となる。また、第１端１４Ｂの付近で、前記の他の第１作用部に対向する箇所の面が、他の第２作用部となる。また、他の第１作用部と他の第２作用部との間に配される間隙が、第２間隙となる。
【００６８】
（３）第３実施形態
本発明は、上記した第１、２実施形態以外の他の構成によっても、実現可能である。図７は、本発明の第３実施形態である荷重測定装置の構成を示す図である。
【００６９】
図７に示すように、この荷重測定装置１Ｃは、第１直線部材１１Ｃと、第２直線部材１２Ｃと、接合部材１３Ｃと、歪みゲージ８０と、載荷用スピンドル２３Ｃ及び２４Ｃを備えて構成されている。図１ないし図３の第１実施形態１Ａと、図７の第３実施形態１Ｃは、第１直線部材と第２直線部材、及び載荷用スピンドルの上下関係が逆になっている。
【００７０】
第１直線部材１１Ｃは、鋼等の弾性体からなり、直線棒状に形成されている。また、第２直線部材１２Ｃは、鋼等の弾性体からなり、直線棒状に形成されている。第１直線部材１１Ｃと第２直線部材１２Ｃは、互いに平行となるように配置され、両者の間には第１間隙１９Ｃが配設されている。
【００７１】
また、第１直線部材１１Ｃと第２直線部材１２Ｃのうち、同じ側で隣接する２個の端部どうし、図７における第１直線部材１１Ｃの左側の端部と、第２直線部材１２Ｃの左側の端部は、接合部材１３Ｃによって接合されている。接合部材１３Ｃは、鋼等の弾性体からなり、弧状に形成されている。ここに、第１直線部材１１Ｃと、第２直線部材１２Ｃと、接合部材１３Ｃは、全体が略Ｕ字状となる外力応答体１０Ｃを構成している。
【００７２】
第２直線部材１２Ｃの内面の先端となる第１端１４Ｃの付近からは、第１端１４Ｃに対向する直線部材である第１直線部材１１Ｃの端である第２端１５Ｃの付近へ向けて、突出部１６Ｃ１と突出部１６Ｃ２が突設されている。突出部１６Ｃ２は、略Ｌ字状に構成されている。図７の場合、第２直線部材１２Ｃは、特許請求の範囲における最外直線部材及び梁状部材に相当している。
【００７３】
また、突出部１６Ｃ１の先端付近の面１７Ｃ１は、第１作用部を構成している。また、第２端１５Ｃの付近で第１作用部１７Ｃ１に対向する箇所の面１８Ｃ１は、第２作用部を構成している。第１作用部１７Ｃ１と第２作用部１８Ｃ１との間には、第２間隙２０Ｃ１が配設されている。この第２間隙２０Ｃ１は、特許請求の範囲における構造変換用間隙に相当している。
【００７４】
さらに、略Ｌ字状の突出部１６Ｃ２の先端付近は、第１直線部材１１Ｃの下部へ回り込むように図７の左側へ向けて略直角に屈曲した屈曲端部１７Ｃ２となっており、この屈曲端部１７Ｃ２は、第１作用部を構成している。また、第２端１５Ｃの付近で第１作用部１７Ｃ２に対向する箇所の面１８Ｃ２は、第２作用部を構成している。第２作用部１８Ｃ２は、第１作用部１７Ｃ２によって係止可能であり、第２作用部１８Ｃ２は、第１作用部１７Ｃ２に対して被係止部となっている。第１作用部１７Ｃ２と第２作用部１８Ｃ２との間には、第２間隙２０Ｃ２が配設されている。この第２間隙２０Ｃ２は、特許請求の範囲における構造変換用間隙に相当している。
【００７５】
また、接合部材１３Ｃの外面には、歪みゲージ８０が貼付されている。この場合には、接合部材１３Ｃは、特許請求の範囲における最外接合部材に相当している。歪みゲージ８０は、上記の従来例における歪みゲージと同一の構成及び作用を有している。
【００７６】
また、第１直線部材１１Ｃの外面の略中央には、雌ネジ孔２１Ｃが形成され、この雌ネジ孔２１Ｃに、載荷用スピンドル２３Ｃの外周の雄ネジが螺合するようになっている。また、第２直線部材１２Ｃの外面の略中央には、雌ネジ孔２２Ｃが形成され、この雌ネジ孔２２Ｃに、載荷用スピンドル２４Ｃの外周の雄ネジが螺合するようになっている。このような構成により、載荷用スピンドル２３Ｃが雌ネジ孔２１Ｃにねじ込まれて取り付けられ、載荷用スピンドル２４Ｃが雌ネジ孔２２Ｃにねじ込まれて取り付けられる。
【００７７】
上記した第３実施形態の荷重測定装置１Ｃは、第１実施形態の荷重測定装置１Ａと第２実施形態の荷重測定装置１Ｂを合体させた構成を有しており、その作用も、第１実施形態の荷重測定装置１Ａと第２実施形態の荷重測定装置１Ｂの両者の機能を併せ持っている。したがって、この第３実施形態の荷重測定装置１Ｃを用いれば、上記した第１実施形態の荷重測定装置１Ａの荷重測定方法と、第２実施形態の荷重測定装置１Ｂの荷重測定方法の両方を１台の装置で行うことができ、小荷重から大荷重まで、広いダイナミック・レンジで荷重測定を行うことができる、という利点を有している。
【００７８】
（４）第４実施形態
本発明は、上記した第１ないし第３実施形態以外の他の構成によっても、実現可能である。図８は、本発明の第４実施形態である荷重測定装置の構成を示す図である。
【００７９】
図８に示すように、この荷重測定装置１Ｄは、第１直線部材１１Ｄと、第２直線部材１２Ｄと、第３直線部材３３Ｄと、接合部材１３Ｄ１及び１３Ｄ２と、２つの歪みゲージ８０、８０と、載荷用スピンドル２３Ｄ及び２４Ｄを備えて構成されている。
【００８０】
第１直線部材１１Ｄは、鋼等の弾性体からなり、直線棒状に形成されている。また、第２直線部材１２Ｄは、鋼等の弾性体からなり、直線棒状に形成されている。また、第３直線部材３３Ｄは、鋼等の弾性体からなり、直線棒状に形成されている。第１直線部材１１Ｄと第２直線部材１２Ｄは、互いに平行となるように配置され、両者の間には第１間隙１９Ｄ１が配設されている。また、第２直線部材１２Ｄと第３直線部材３３Ｄは、互いに平行となるように配置され、両者の間には第１間隙１９Ｄ２が配設されている。
【００８１】
また、第１直線部材１１Ｄと第２直線部材１２Ｄのうち、同じ側で隣接する２個の端部どうし、図８における第１直線部材１１Ｄの左側の端部と、第２直線部材１２Ｄの左側の端部は、接合部材１３Ｄ１によって接合されている。接合部材１３Ｄ１は、鋼等の弾性体からなり、弧状に形成されている。また、第２直線部材１２Ｄと第３直線部材３３Ｄのうち、同じ側で隣接する２個の端部どうし、図８における第２直線部材１２Ｄの右側の端部と、第３直線部材３３Ｄの右側の端部は、接合部材１３Ｄ２によって接合されている。接合部材１３Ｄ２は、鋼等の弾性体からなり、弧状に形成されている。ここに、第１直線部材１１Ｄと、第２直線部材１２Ｄと、接合部材１３Ｄ１と、第３直線部材３３Ｄと、接合部材１３Ｄ２は、全体が略Ｓ字状となる外力応答体１０Ｄを構成している。
【００８２】
第１直線部材１１Ｄの内面の先端となる第１端１４Ｄ１の付近からは、第１端１４Ｄ１に対向する直線部材である第２直線部材１２Ｄの端である第２端１５Ｄ１の付近へ向けて、突出部１６Ｄ１が突設されている。また、第３直線部材３３Ｄの内面の先端となる第１端１４Ｄ２の付近からは、第１端１４Ｄ２に対向する直線部材である第２直線部材１２Ｄの端である第２端１５Ｄ２の付近へ向けて、突出部１６Ｄ２が突設されている。図８の場合、第１直線部材１１Ｄ及び第３直線部材３３Ｄは、特許請求の範囲における最外直線部材及び梁状部材に相当している。
【００８３】
また、突出部１６Ｄ１の先端付近の面１７Ｄ１は、第１作用部を構成している。また、第２端１５Ｄ１の付近で第１作用部１７Ｄ１に対向する箇所の面１８Ｄ１は、第２作用部を構成している。第１作用部１７Ｄ１と第２作用部１８Ｄ１との間には、第２間隙２０Ｄ１が配設されている。この第２間隙２０Ｄ１は、特許請求の範囲における構造変換用間隙に相当している。
【００８４】
また、突出部１６Ｄ２の先端付近の面１７Ｄ２は、第１作用部を構成している。また、第２端１５Ｄ２の付近で第１作用部１７Ｄ２に対向する箇所の面１８Ｄ２は、第２作用部を構成している。第１作用部１７Ｄ２と第２作用部１８Ｄ２との間には、第２間隙２０Ｄ２が配設されている。この第２間隙２０Ｄ２は、特許請求の範囲における構造変換用間隙に相当している。
【００８５】
また、接合部材１３Ｄ１の外面、及び接合部材１３Ｄ２の外面には、それぞれ歪みゲージ８０が貼付されている。この場合には、接合部材１３Ｄ１及び１３Ｄ２は、特許請求の範囲における最外接合部材に相当している。歪みゲージ８０は、上記の従来例における歪みゲージと同一の構成及び作用を有している。
【００８６】
また、第１直線部材１１Ｄの外面の略中央には、雌ネジ孔２１Ｄが形成され、この雌ネジ孔２１Ｄに、載荷用スピンドル２３Ｄの外周の雄ネジが螺合するようになっている。また、第３直線部材３３Ｄの外面の略中央には、雌ネジ孔２２Ｄが形成され、この雌ネジ孔２２Ｄに、載荷用スピンドル２４Ｄの外周の雄ネジが螺合するようになっている。このような構成により、載荷用スピンドル２３Ｄが雌ネジ孔２１Ｄにねじ込まれて取り付けられ、載荷用スピンドル２４Ｄが雌ネジ孔２２Ｄにねじ込まれて取り付けられる。
【００８７】
上記した第４実施形態の荷重測定装置１Ｄは、３個の直線部材の端部を交互に接合部材で接合し、外力応答体が全体として略Ｓ字状となるように構成したものである。この第４実施形態の荷重測定装置１Ｄは、第１実施形態の荷重測定装置１Ａと同様の原理により、圧縮荷重Ｐの測定が可能となっており、圧縮荷重Ｐがある荷重値（第１荷重値）以上となると、機械的な作用（メカニズム）が働いて外力応答体１０Ｄの構造系が変換され、歪み測定の感度を下げることができ、小荷重から大荷重まで、広いダイナミック・レンジで荷重測定を行うことができる、という利点を有している。
【００８８】
（５）第５実施形態
本発明は、上記した第１ないし第４実施形態以外の他の構成によっても、実現可能である。図９は、本発明の第５実施形態である荷重測定装置の構成を示す図である。
【００８９】
図９に示すように、この荷重測定装置１Ｅは、第１直線部材１１Ｅと、第２直線部材１２Ｅと、第３直線部材３３Ｅと、接合部材１３Ｅ１及び１３Ｅ２と、２つの歪みゲージ８０、８０と、載荷用スピンドル２３Ｅ及び２４Ｅを備えて構成されている。
【００９０】
第１直線部材１１Ｅは、鋼等の弾性体からなり、直線棒状に形成されている。また、第２直線部材１２Ｅは、鋼等の弾性体からなり、直線棒状に形成されている。また、第３直線部材３３Ｅは、鋼等の弾性体からなり、直線棒状に形成されている。第１直線部材１１Ｅと第２直線部材１２Ｅは、互いに平行となるように配置され、両者の間には第１間隙１９Ｅ１が配設されている。また、第２直線部材１２Ｅと第３直線部材３３Ｅは、互いに平行となるように配置され、両者の間には第１間隙１９Ｅ２が配設されている。
【００９１】
また、第１直線部材１１Ｅと第２直線部材１２Ｅのうち、同じ側で隣接する２個の端部どうし、図９における第１直線部材１１Ｅの左側の端部と、第２直線部材１２Ｅの左側の端部は、接合部材１３Ｅ１によって接合されている。接合部材１３Ｅ１は、鋼等の弾性体からなり、弧状に形成されている。また、第２直線部材１２Ｅと第３直線部材３３Ｅのうち、同じ側で隣接する２個の端部どうし、図９における第２直線部材１２Ｅの右側の端部と、第３直線部材３３Ｅの右側の端部は、接合部材１３Ｅ２によって接合されている。接合部材１３Ｅ２は、鋼等の弾性体からなり、弧状に形成されている。ここに、第１直線部材１１Ｅと、第２直線部材１２Ｅと、接合部材１３Ｅ１と、第３直線部材３３Ｅと、接合部材１３Ｅ２は、全体が略Ｓ字状となる外力応答体１０Ｅを構成している。
【００９２】
第２直線部材１２Ｅの内面の先端となる第１端１４Ｅ１の付近からは、第１端１４Ｅ１に対向する直線部材である第１直線部材１１Ｅの端である第２端１５Ｅ１の付近へ向けて、突出部１６Ｅ１が突設されている。突出部１６Ｅ１は、略Ｌ字状に構成されている。また、第２直線部材１２Ｅの内面の先端となる第１端１４Ｅ２の付近からは、第１端１４Ｅ２に対向する直線部材である第３直線部材３３Ｅの端である第２端１５Ｅ２の付近へ向けて、突出部１６Ｅ２が突設されている。突出部１６Ｅ２は、略Ｌ字状に構成されている。図９の場合、第１直線部材１１Ｅ及び第３直線部材３３Ｅは、特許請求の範囲における最外直線部材及び梁状部材に相当している。
【００９３】
また、略Ｌ字状の突出部１６Ｅ１の先端付近は、第１直線部材１１Ｅの下部へ回り込むように図９の左側へ向けて略直角に屈曲した屈曲端部１７Ｅ１となっており、この屈曲端部１７Ｅ１は、第１作用部を構成している。また、第２端１５Ｅの付近で第１作用部１７Ｅ１に対向する箇所の面１８Ｅ１は、第２作用部を構成している。第２作用部１８Ｅ１は、第１作用部１７Ｅ１によって係止可能であり、第２作用部１８Ｅ１は、第１作用部１７Ｅ１に対して被係止部となっている。第１作用部１７Ｅ１と第２作用部１８Ｅ１との間には、第２間隙２０Ｅ１が配設されている。この第２間隙２０Ｅ１は、特許請求の範囲における構造変換用間隙に相当している。
【００９４】
また、略Ｌ字状の突出部１６Ｅ２の先端付近は、第３直線部材３３Ｅの下部へ回り込むように図９の右側へ向けて略直角に屈曲した屈曲端部１７Ｅ２となっており、この屈曲端部１７Ｅ２は、第１作用部を構成している。また、第２端１５Ｅの付近で第１作用部１７Ｅ２に対向する箇所の面１８Ｅ２は、第２作用部を構成している。第２作用部１８Ｅ２は、第１作用部１７Ｅ２によって係止可能であり、第２作用部１８Ｅ２は、第１作用部１７Ｅ２に対して被係止部となっている。第１作用部１７Ｅ２と第２作用部１８Ｅ２との間には、第２間隙２０Ｅ２が配設されている。この第２間隙２０Ｅ２は、特許請求の範囲における構造変換用間隙に相当している。
【００９５】
また、接合部材１３Ｅ１の外面、及び接合部材１３Ｅ２の外面には、それぞれ歪みゲージ８０が貼付されている。この場合には、接合部材１３Ｅ１及び１３Ｅ２は、特許請求の範囲における最外接合部材に相当している。歪みゲージ８０は、上記の従来例における歪みゲージと同一の構成及び作用を有している。
【００９６】
また、第１直線部材１１Ｅの外面の略中央には、雌ネジ孔２１Ｅが形成され、この雌ネジ孔２１Ｅに、載荷用スピンドル２３Ｅの外周の雄ネジが螺合するようになっている。また、第３直線部材３３Ｅの外面の略中央には、雌ネジ孔２２Ｅが形成され、この雌ネジ孔２２Ｅに、載荷用スピンドル２４Ｅの外周の雄ネジが螺合するようになっている。このような構成により、載荷用スピンドル２３Ｅが雌ネジ孔２１Ｅにねじ込まれて取り付けられ、載荷用スピンドル２４Ｅが雌ネジ孔２２Ｅにねじ込まれて取り付けられる。
【００９７】
上記した第５実施形態の荷重測定装置１Ｅは、３個の直線部材の端部を交互に接合部材で接合し、外力応答体が全体として略Ｓ字状となるように構成したものである。この第５実施形態の荷重測定装置１Ｅは、第２実施形態の荷重測定装置１Ｂと同様の原理により、引張荷重Ｔの測定が可能となっており、引張荷重Ｔがある荷重値（第１荷重値）以上となると、機械的な作用（メカニズム）が働いて外力応答体１０Ｅの構造系が変換され、歪み測定の感度を下げることができ、小荷重から大荷重まで、広いダイナミック・レンジで荷重測定を行うことができる、という利点を有している。
【００９８】
（６）第６実施形態
本発明は、上記した第１ないし第５実施形態以外の他の構成によっても、実現可能である。図１０は、本発明の第６実施形態である荷重測定装置の構成を示す図である。
【００９９】
図１０に示すように、この荷重測定装置１Ｆは、第１直線部材１１Ｆと、第２直線部材１２Ｆと、第３直線部材３３Ｆと、接合部材１３Ｆ１及び１３Ｆ２と、２つの歪みゲージ８０、８０と、載荷用スピンドル２３Ｆ及び２４Ｆを備えて構成されている。
【０１００】
第１直線部材１１Ｆは、鋼等の弾性体からなり、直線棒状に形成されている。また、第２直線部材１２Ｆは、鋼等の弾性体からなり、直線棒状に形成されている。また、第３直線部材３３Ｆは、鋼等の弾性体からなり、直線棒状に形成されている。第１直線部材１１Ｆと第２直線部材１２Ｆは、互いに平行となるように配置され、両者の間には第１間隙１９Ｆ１が配設されている。また、第２直線部材１２Ｆと第３直線部材３３Ｆは、互いに平行となるように配置され、両者の間には第１間隙１９Ｆ２が配設されている。
【０１０１】
また、第１直線部材１１Ｆと第２直線部材１２Ｆのうち、同じ側で隣接する２個の端部どうし、図１０における第１直線部材１１Ｆの左側の端部と、第２直線部材１２Ｆの左側の端部は、接合部材１３Ｆ１によって接合されている。接合部材１３Ｆ１は、鋼等の弾性体からなり、弧状に形成されている。また、第２直線部材１２Ｆと第３直線部材３３Ｆのうち、同じ側で隣接する２個の端部どうし、図１０における第２直線部材１２Ｆの右側の端部と、第３直線部材３３Ｆの右側の端部は、接合部材１３Ｆ２によって接合されている。接合部材１３Ｆ２は、鋼等の弾性体からなり、弧状に形成されている。ここに、第１直線部材１１Ｆと、第２直線部材１２Ｆと、接合部材１３Ｆ１と、第３直線部材３３Ｆと、接合部材１３Ｆ２は、全体が略Ｓ字状となる外力応答体１０Ｆを構成している。
【０１０２】
第２直線部材１２Ｆの内面の先端となる第１端１４Ｆ１の付近からは、第１端１４Ｆ１に対向する直線部材である第１直線部材１１Ｆの端である第２端１５Ｆ１の付近へ向けて、突出部１６Ｆ１１突出部１６Ｆ１２とが突設されている。突出部１６Ｆ１２は、略Ｌ字状に構成されている。また、第２直線部材１２Ｆの内面の先端となる第１端１４Ｆ２の付近からは、第１端１４Ｆ２に対向する直線部材である第３直線部材３３Ｆの端である第２端１５Ｆ２の付近へ向けて、突出部１６Ｆ２１と突出部１６Ｆ２２が突設されている。突出部１６Ｆ２２は、略Ｌ字状に構成されている。図１０の場合、第１直線部材１１Ｆ及び第３直線部材３３Ｆは、特許請求の範囲における最外直線部材及び梁状部材に相当している。
【０１０３】
また、突出部１６Ｆ１１の先端付近の面１７Ｆ１１は、第１作用部を構成している。また、第２端１５Ｆ１の付近で第１作用部１７Ｆ１１に対向する箇所の面１８Ｆ１１は、第２作用部を構成している。第１作用部１７Ｆ１１と第２作用部１８Ｆ１１との間には、第２間隙２０Ｆ１１が配設されている。この第２間隙２０Ｆ１１は、特許請求の範囲における構造変換用間隙に相当している。
【０１０４】
また、略Ｌ字状の突出部１６Ｆ１２の先端付近は、第１直線部材１１Ｆの下部へ回り込むように図１０の左側へ向けて略直角に屈曲した屈曲端部１７Ｆ１２となっており、この屈曲端部１７Ｆ１２は、第１作用部を構成している。また、第２端１５Ｆ１の付近で第１作用部１７Ｆ１２に対向する箇所の面１８Ｆ１２は、第２作用部を構成している。第２作用部１８Ｆ１２は、第１作用部１７Ｆ１２によって係止可能であり、第２作用部１８Ｆ１２は、第１作用部１７Ｆ１２に対して被係止部となっている。第１作用部１７Ｆ１２と第２作用部１８Ｆ１２との間には、第２間隙２０Ｆ１２が配設されている。この第２間隙２０Ｆ１２は、特許請求の範囲における構造変換用間隙に相当している。
【０１０５】
また、突出部１６Ｆ２１の先端付近の面１７Ｆ２１は、第１作用部を構成している。また、第２端１５Ｆ２の付近で第１作用部１７Ｆ２１に対向する箇所の面１８Ｆ２１は、第２作用部を構成している。第１作用部１７Ｆ２１と第２作用部１８Ｆ２１との間には、第２間隙２０Ｆ２１が配設されている。この第２間隙２０Ｆ２１は、特許請求の範囲における構造変換用間隙に相当している。
【０１０６】
また、略Ｌ字状の突出部１６Ｆ２２の先端付近は、第３直線部材３３Ｆの下部へ回り込むように図１０の右側へ向けて略直角に屈曲した屈曲端部１７Ｆ２２となっており、この屈曲端部１７Ｆ２２は、第１作用部を構成している。また、第２端１５Ｆ２の付近で第１作用部１７Ｆ２２に対向する箇所の面１８Ｆ２２は、第２作用部を構成している。第２作用部１８Ｆ２２は、第１作用部１７Ｆ２２によって係止可能であり、第２作用部１８Ｆ２２は、第１作用部１７Ｆ２２に対して被係止部となっている。第１作用部１７Ｆ２２と第２作用部１８Ｆ２２との間には、第２間隙２０Ｆ２２が配設されている。この第２間隙２０Ｆ２２は、特許請求の範囲における構造変換用間隙に相当している。
【０１０７】
また、接合部材１３Ｆ１の外面、及び接合部材１３Ｆ２の外面には、それぞれ歪みゲージ８０が貼付されている。この場合には、接合部材１３Ｆ１及び１３Ｆ２は、特許請求の範囲における最外接合部材に相当している。歪みゲージ８０は、上記の従来例における歪みゲージと同一の構成及び作用を有している。
【０１０８】
また、第１直線部材１１Ｆの外面の略中央には、雌ネジ孔２１Ｆが形成され、この雌ネジ孔２１Ｆに、載荷用スピンドル２３Ｆの外周の雄ネジが螺合するようになっている。また、第３直線部材３３Ｆの外面の略中央には、雌ネジ孔２２Ｆが形成され、この雌ネジ孔２２Ｆに、載荷用スピンドル２４Ｆの外周の雄ネジが螺合するようになっている。このような構成により、載荷用スピンドル２３Ｆが雌ネジ孔２１Ｆにねじ込まれて取り付けられ、載荷用スピンドル２４Ｆが雌ネジ孔２２Ｆにねじ込まれて取り付けられる。
【０１０９】
上記した第６実施形態の荷重測定装置１Ｆは、３個の直線部材の端部を交互に接合部材で接合し、外力応答体が全体として略Ｓ字状となるように構成したものである。この第６実施形態の荷重測定装置１Ｆは、第２実施形態の荷重測定装置１Ｃと同様の原理により、圧縮荷重Ｐと引張荷重Ｔの両方の測定が可能となっており、圧縮荷重Ｐ又は引張荷重Ｔがある荷重値（第１荷重値）以上となると、機械的な作用（メカニズム）が働いて外力応答体１０Ｆの構造系が変換され、歪み測定の感度を下げることができ、小荷重から大荷重まで、広いダイナミック・レンジで荷重測定を行うことができる、という利点を有している。
【０１１０】
なお、本発明は、上記した各実施形態に限定されるものではない。上記した各実施形態や例は、例示であり、本発明の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本発明の技術的範囲に包含される。
【０１１１】
例えば、上記各実施形態においては、接合部材として、弧状に形成された部材を例に挙げて説明したが、本発明はこれには限定されず、接合部材は隣接する２個の直線部材を接合できればよく、直線状の部材であってもよい。したがって、外力応答体全体としては、略Ｕ字状の構成のほか、略コ字状の構成であってもよい。あるいは、外力応答体全体としては、略Ｓ字状の構成のほか、隅角部が略直角状の略Ｓ字状の構成であってもよい。あるいは、外力応答体全体としては、隅角部が滑らかな略波形状の構成のほか、隅角部が略直角状の略波形状の構成であってもよい。
【０１１２】
上記した実施形態においては、外力応答体として、直線部材２個と接合部材１個により全体として略Ｕ字状となるもの、及び直線部材３個と接合部材２個により全体として略Ｓ字状となるものを例に挙げて説明したが、本発明はこれには限定されず、外力応答体は、他の構成、例えば、直線部材Ｎ（Ｎ：２以上の整数）個と接合部材（Ｎ−１）個により全体として略波形状となるものであってもよい。この場合には、外力応答体は、直線棒状に形成されたＮ（Ｎ：２以上の整数）個の直線部材を互いに平行に第１間隙を配して配置し、前記Ｎ個の直線部材のうち同じ側で隣接する２個の端部どうしを（Ｎ−１）個の接合部材で交互に接合して構成される略Ｕ字状又は略Ｓ字状若しくは略波形状の外力応答体となり、前記直線部材のうち最も外側となる直線部材である最外直線部材の内面の先端となる第１端の付近から前記第１端に対向する他の直線部材の端である第２端の付近へ向けて、又は前記第２端の付近から前記第１端の付近へ向けて、それぞれ突出部が突設されるとともに、前記突出部の先端付近に設けられる第１作用部と、前記第２端又は前記第１端の付近で前記第１作用部に対向する箇所に設けられる第２作用部との間に、第２間隙が設けられることとなる。
【０１１３】
また、上記各実施形態においては、荷重が載荷用スピンドルによって載荷される例について説明したが、本発明はこれには限定されず、載荷方法は、他の方法でもよい。例えば、ボルトによりスピンドルを直線部材に固定する方法でもよい。また、圧縮荷重の場合には、凹部にスピンドル状の部材を挿入するだけでも載荷は可能である。
【０１１４】
上記各実施形態により、圧縮荷重と引張荷重の測定が可能である。また、剪断力は、例えば長方形状の部材の底辺を固定し、上辺に水平力として圧縮荷重又は引張荷重を載荷すればよい。また、ねじりモーメントは、軸が回転しないように固定し軸中心線のまわりのモーメントとなるように軸の所定箇所に圧縮荷重又は引張荷重を載荷すればよい。したがって、上記各実施形態で説明した圧縮荷重測定、あるいは引張荷重測定を応用することにより、本発明の荷重測定装置又は荷重測定方法を用いて、剪断力やねじりモーメントも測定することができる。
【０１１５】
なお、上記した荷重測定装置における第１荷重値や、全体としての最大測定荷重値は、各部材の材質（強度、弾性係数など）、各部材の寸法（部材長さ、断面積、断面２次モーメントなど）、第１間隙の値、第２間隙の値、などを適宜に設定することにより、所望の値のものを得ることができる。
【０１１６】
上記した本発明の原理より、本発明は、上記した実施形態以外の構造によっても実現可能である。すなわち、図１１（Ａ）に示すように、鋼等の弾性体からなり、一端（固定端４３Ｇ）が強固な床又は壁等からなる不動部４５Ｇで固定され、他端４４Ｇが自由状態となっている曲がり梁状の梁状部材４１Ｇの略中央に圧縮荷重Ｐが載荷されるようにし、自由端４４Ｇの下方に不動部４６Ｇを設け、当該不動部４６Ｇと自由端４４Ｇとの間に構造変換用間隙４７Ｇを設けて外力応答体１０Ｇを構成し、外力応答体１０Ｇの固定端４３Ｇ付近の表面に歪みゲージ８０を貼付するように構成してもよい。このように構成すれば、荷重Ｐが第１荷重値未満の場合には自由端４４Ｇが不動部４６Ｇに接近するように変形し、圧縮荷重Ｐが第１荷重値と等しくなった場合には自由端４４Ｇが不動部４６Ｇに接触し、圧縮荷重Ｐが第１荷重値を越えた場合には自由端４４Ｇが不動部４６Ｇに接触した状態で梁状部材４１Ｇの略中央が不動部４８Ｇに接近するように変形するように構成し、歪みゲージ８０の出力から圧縮荷重Ｐの値を測定することができる。
【０１１７】
また、本発明は、上記した実施形態以外の構造によっても実現可能である。すなわち、図１１（Ｂ）に示すように、鋼等の弾性体からなり、一端（固定端４３Ｈ）が強固な床又は壁等からなる不動部４５Ｈで固定され、他端４４Ｈが自由状態となっている直線梁状の梁状部材４１Ｈの略中央に圧縮荷重Ｐが載荷されるようにし、自由端４４Ｈの下方に不動部４６Ｈを設け、当該不動部４６Ｈと自由端４４Ｈとの間に構造変換用間隙４７Ｈを設けて外力応答体１０Ｈを構成し、外力応答体１０Ｈの固定端４３Ｈ付近の表面に歪みゲージ８０を貼付するように構成してもよい。このように構成すれば、圧縮荷重Ｐが第１荷重値未満の場合には自由端４４Ｈが不動部４６Ｈに接近するように変形し、圧縮荷重Ｐが第１荷重値と等しくなった場合には自由端４４Ｈが不動部４６Ｈに接触し、圧縮荷重Ｐが第１荷重値を越えた場合には自由端４４Ｈが不動部４６Ｈに接触した状態で梁状部材４１Ｈの略中央が不動部４８Ｈに接近するように変形するように構成し、歪みゲージ８０の出力から圧縮荷重Ｐの値を測定することができる。
【０１１８】
また、本発明は、上記した実施形態以外の構造によっても実現可能である。すなわち、図１１（Ｃ）に示すように、鋼等の弾性体からなり、一端（固定端４３Ｊ）が強固な床又は壁等からなる不動部４５Ｊで固定され、他端４４Ｊが自由状態となっている曲がり梁状の梁状部材４１Ｊの略中央に引張荷重Ｔが載荷されるようにし、自由端４４Ｊの上方に不動部４６Ｊを設け、当該不動部４６Ｊと自由端４４Ｊとの間に構造変換用間隙４７Ｊを設けて外力応答体１０Ｊを構成し、外力応答体１０Ｊの固定端４３Ｊ付近の表面に歪みゲージ８０を貼付するように構成してもよい。このように構成すれば、荷重Ｔが第１荷重値未満の場合には自由端４４Ｊが不動部４６Ｊに接近するように変形し、引張荷重Ｔが第１荷重値と等しくなった場合には自由端４４Ｊが不動部４６Ｊに接触し、引張荷重Ｔが第１荷重値を越えた場合には自由端４４Ｊが不動部４６Ｊに接触した状態で梁状部材４１Ｊの略中央が不動部４８Ｊに接近するように変形するように構成し、歪みゲージ８０の出力から引張荷重Ｔの値を測定することができる。
【０１１９】
また、本発明は、上記した実施形態以外の構造によっても実現可能である。すなわち、図１１（Ｄ）に示すように、鋼等の弾性体からなり、一端（固定端４３Ｋ）が強固な床又は壁等からなる不動部４５Ｋで固定され、他端４４Ｋが自由状態となっている直線梁状の梁状部材４１Ｋの略中央に引張荷重Ｔが載荷されるようにし、自由端４４Ｋの上方に不動部４６Ｋを設け、当該不動部４６Ｋと自由端４４Ｋとの間に構造変換用間隙４７Ｋを設けて外力応答体１０Ｋを構成し、外力応答体１０Ｋの固定端４３Ｋ付近の表面に歪みゲージ８０を貼付するように構成してもよい。このように構成すれば、引張荷重Ｔが第１荷重値未満の場合には自由端４４Ｋが不動部４６Ｋに接近するように変形し、引張荷重Ｔが第１荷重値と等しくなった場合には自由端４４Ｋが不動部４６Ｋに接触し、引張荷重Ｔが第１荷重値を越えた場合には自由端４４Ｋが不動部４６Ｋに接触した状態で梁状部材４１Ｋの略中央が不動部４８Ｋに接近するように変形するように構成し、歪みゲージ８０の出力から引張荷重Ｔの値を測定することができる。
【０１２０】
【発明の効果】
以上説明したように、本発明に係る荷重測定装置、及び荷重測定方法によれば、弾性体からなり、一端で固定され他端が自由状態の梁状部材の略中央に荷重が載荷されるようにし、自由端の下方又は上方に不動部を設け、当該不動部と自由端との間に構造変換用間隙を設けて外力応答体を構成し、外力応答体の固定端付近の表面に歪みゲージを貼付するように構成したので、荷重が第１荷重値未満の場合には自由端が不動部に接近するように変形させ、荷重が第１荷重値と等しくなった場合には自由端が不動部に接触させ、荷重が第１荷重値を越えた場合には自由端が不動部に接触した状態で梁状部材の略中央が不動部に接近するように変形させ、歪みゲージの出力から荷重の値を測定することができる。この場合、小荷重から大荷重まで、広いダイナミック・レンジで荷重測定を行うことができる、という利点を有している。
【図面の簡単な説明】
【図１】本発明の第１実施形態である荷重測定装置の構成を示す図である。
【図２】第１実施形態の荷重測定装置において載荷により第１作用部と第２作用部が互いに接触した状態を示す図である。
【図３】第１実施形態の荷重測定装置において載荷により第１作用部と第２作用部が互いに接触した状態で第２直線部材の略中央と第１直線部材が互いに接近するように変形している状態を示す図である。
【図４】本発明に係る荷重測定装置の作用原理を説明する概念図である。
【図５】本発明の第２実施形態である荷重測定装置の構成を示す図である。
【図６】第２実施形態の荷重測定装置において載荷により第１作用部と第２作用部が互いに接触した状態を示す図である。
【図７】本発明の第３実施形態である荷重測定装置の構成を示す図である。
【図８】本発明の第４実施形態である荷重測定装置の構成を示す図である。
【図９】本発明の第５実施形態である荷重測定装置の構成を示す図である。
【図１０】本発明の第６実施形態である荷重測定装置の構成を示す図である。
【図１１】本発明の他の実施形態である荷重測定装置における外力応答体の構成を示す図である。
【図１２】従来の歪みゲージの構成を示す図である。
【図１３】弾性体の応力と歪みの関係を示す概念図である。
【符号の説明】
１Ａ〜１Ｋ 荷重測定装置
１０Ａ〜１０Ｋ 外力応答体
１１Ａ〜１１Ｆ 第１直線部材
１２Ａ〜１２Ｆ 第２直線部材
１３Ａ〜１３Ｆ２ 接合部材
１４Ａ〜１４Ｆ２ 第１端
１５Ａ〜１５Ｆ２ 第２端
１６Ａ〜１６Ｆ２２ 突出部
１７Ａ〜１７Ｆ２２ 第１作用部
１８Ａ〜１８Ｆ２２ 第２作用部
１９Ａ〜１９Ｆ２ 第１間隙
２０Ａ〜２０Ｆ２２ 第２間隙
２１Ａ〜２１Ｆ 第１雌ネジ孔
２２Ａ〜２２Ｆ 第２雌ネジ孔
２３Ａ〜２３Ｆ 載荷用スピンドル
２４Ａ〜２４Ｆ 載荷用スピンドル
３３Ｄ〜３３Ｆ 第３直線部材
４１Ｇ〜４１Ｋ 梁状部材
４２Ｇ、４２Ｊ 直線部
４３Ｇ〜４３Ｋ 固定端
４４Ｇ〜４４Ｋ 自由端
４５Ｇ〜４５Ｋ 不動部
４６Ｇ〜４６Ｋ 不動部
４７Ｇ〜４７Ｋ 構造変換用間隙
４８Ｇ〜４８Ｋ 不動部
８０ 歪みゲージ
８１ ゲージベース
８２ 抵抗部
８３、８４ リード線
Ｐ 圧縮荷重
Ｔ 引張荷重
Ｚ 破断点[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a load measuring device and a load measuring method, and more particularly to a load measuring device and a load measuring method capable of measuring loads in a wide range from a small load to a large load.
[0002]
[Prior art]
Conventionally, a load cell (for example, see Patent Document 1) has been used as an apparatus for measuring a load acting on a structure or the like. The load cell (not shown) is formed by attaching a strain gauge to a force detecting member made of an elastic body such as steel. When measuring a load with a load cell, a load is applied to the force detecting member, and a change in strain caused by the deformation of the force detecting member due to the load is measured as a change in the electric resistance value of the strain gauge.
[0003]
Next, the strain gauge will be described. As shown in FIG. 12, the strain gauge 80 includes a gauge base 81, a resistor 82, and leads 83 and 84. The gauge base 81 is made of an electrically insulating material such as paper or polyester resin, and is formed in a thin film shape. The resistance portion 82 is made of a metal, a semiconductor, or the like, and is formed in a linear shape or a foil shape. The length LG of the resistance portion 82 is called a gauge length. The strain gauge 80 is used by being attached to the surface of the object to be measured with an adhesive or the like.
[0004]
When an external force is applied to the object to be measured, a stress is generated on the surface of the object to be measured, which is a position where the strain gauge 80 is attached, and an extension or contraction amount ΔL is generated in the gauge length LG of the resistance portion 82. The ratio between ΔL and LG (ΔL / LG) is called “distortion” and is equal to “surface distortion” generated on the surface of the measured object. The resistance of a metal or the like changes in proportion to the strain. When the resistance value of the strain gauge 80 is R, the strain is ε (= ΔL / LG), and the change in the resistance value of the strain gauge 80 due to the strain ε is ΔR, the following equation (1) holds.
ΔR / R = K × ε (1)
Here, K is a proportional constant and is called a gauge factor.
[0005]
Further, a relationship represented by the following equation (2) is established between the strain ε and the stress σ (force per unit area obtained by dividing the load by the applied area; unit: Pa Pascal).
σ = E × ε (2)
Here, E (unit: Pa Pascal) is a proportionality constant and is called an elastic modulus or a Young's modulus.
[0006]
The lead wires 83 and 84 of the strain gauge 80 are formed of a conductor such as a metal, and are used for connection to an external electric circuit or the like. Output to
[0007]
If a so-called “Wheatstone bridge circuit” is formed by connecting the four strain gauges 80 in a rhombus shape, it is possible to compensate for the influence of temperature changes and to eliminate errors.
[0008]
[Patent Document 1]
JP-A-7-209102 (page 1-12, FIG. 1-14)
[0009]
[Problems to be solved by the invention]
However, in a load measuring device such as the above-described conventional load cell, the elastic body constituting the force detecting member exhibits the following behavior as the load increases. First, as shown in FIG. p (Hereinafter referred to as “proportional limit stress”), the proportional relationship between strain ε and stress σ shown in the above equation (2) ends, and thereafter, the relationship between strain ε and stress σ becomes a curve instead of a straight line. . Thereafter, when the load is further increased, the stress increases, and the stress becomes the second value σ. E After reaching an elastic limit stress (hereinafter, referred to as “elastic limit stress”), the strain generated in the elastic body remains without returning to zero even if the load is removed. Thereafter, as the load increases, the stress increases to a third value σ y (Hereinafter, referred to as “yield point stress”), and thereafter, the strain starts to increase, and finally reaches fracture (see point Z in FIG. 13).
[0010]
Therefore, since the elastic limit stress of the force detecting member capable of accurately measuring a small load is small, there is a problem that when a large load is applied, the elastic limit is exceeded, and in an extreme case, the force detecting member is broken. In addition, the elastic limit stress of the force detecting member capable of measuring a large load is large, but when a small load is applied, the generated strain value is too small, and the measured value is buried in an error (noise), There has been a problem that accurate measurement becomes very difficult. Therefore, with a conventional load measuring device, it was practically impossible to perform accurate measurement of loads in a wide range of values from a small load to a large load with one device.
[0011]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an apparatus that can accurately measure loads in a wide range of values from a small load to a large load with one device. It is an object of the present invention to provide a load measuring device and a load measuring method which can be performed by the above method.
[0012]
[Means for Solving the Problems]
In order to solve the above problem, the load measuring device according to claim 1 is
A load is applied substantially at the center of a beam-shaped member made of an elastic body, fixed at one end and the other end in a free state. An immovable portion is provided below or above the free end, and the immovable portion and the free end are provided. To provide an external force responsive body by providing a gap for structural conversion between, and affix a strain gauge to the surface near the fixed end of the external force responsive body,
When the load is less than the first load value, the free end is deformed so as to approach the immovable portion, and when the load becomes equal to the first load value, the free end is moved to the immovable portion. When the load exceeds the first load value and the free end is in contact with the immovable portion, the center of the beam-shaped member is deformed so as to approach the immovable portion. Measuring the value of the load from the output of the strain gauge
It is characterized by.
[0013]
The load measuring device according to claim 2 is
N (N: an integer of 2 or more) linear members formed of an elastic body and formed in a linear rod shape are arranged parallel to each other with a first gap therebetween, and are adjacent to each other on the same side of the N linear members. A substantially U-shaped or substantially S-shaped or substantially wave-shaped external force responsive body formed by alternately joining two end portions with (N-1) joining members;
The outermost linear member that is the outermost linear member among the linear members is the beam-shaped member, and is the end of another linear member facing the first end from near the first end that is the tip of the inner surface thereof. A protruding portion is protruded toward the vicinity of the second end or from the vicinity of the second end toward the vicinity of the first end, and a first action portion provided near the tip of the protruding portion. A second gap is provided as the structure conversion gap between the second end or the second end provided near the first end at a location facing the first end;
A strain gauge is attached to the surface of the external force responsive body,
A load is applied to substantially the center of the outer surface of the outermost linear member so as to be on the same axis and have opposite directions. If the load is less than a first load value, the first action portion and the second action portion Are deformed so as to approach each other, and when the load becomes equal to the first load value, the first action portion and the second action portion contact each other, and the load exceeds the first load value. In such a case, the strain gauge is configured such that substantially the center of the outermost linear member and adjacent linear members are deformed so as to approach each other when the first operating portion is in contact with the second operating portion, and the strain gauge Measuring the value of the load from the output of
It is characterized by.
[0014]
The load measuring device according to claim 3 is the load measuring device according to claim 1,
The load is a compressive load, and when the load is less than the first load value, the outermost linear member and an adjacent linear member are deformed so as to approach each other.
It is characterized by.
[0015]
Further, the load measuring device according to claim 4 is the load measuring device according to claim 1,
The load is a tensile load, and when the load is less than the first load value, the outermost linear member and the adjacent linear member are deformed so as to be separated from each other.
It is characterized by.
[0016]
Further, the load measuring device according to claim 5 is the load measuring device according to claim 4,
The protruding portion is formed in a substantially L-shape, and the first operating portion is a bent end of the substantially L-shaped protruding portion,
The second action portion is a locked portion installed so as to be locked by the first action portion.
It is characterized by.
[0017]
The load measuring device according to claim 6 is the load measuring device according to claim 1,
The strain gauge is
The outermost linear member and a linear member adjacent to the outermost linear member are bonded to a surface of an outermost bonding member which is a bonding member for bonding the linear member.
It is characterized by.
[0018]
Further, the load measuring method according to claim 7 is:
A load is applied substantially at the center of a beam-shaped member made of an elastic body, fixed at one end and the other end in a free state. An immovable portion is provided below or above the free end, and the immovable portion and the free end are provided. To provide an external force responsive body by providing a gap for structural conversion between, and affix a strain gauge to the surface near the fixed end of the external force responsive body,
When the load is less than the first load value, the free end is deformed so as to approach the immovable portion, and when the load becomes equal to the first load value, the free end is moved to the immovable portion. When the load exceeds the first load value and the free end is in contact with the immovable portion, the center of the beam-shaped member is deformed so as to approach the immovable portion. Measuring the value of the load from the output of the strain gauge
It is characterized by.
[0019]
Further, the load measuring method described in claim 8 is as follows.
N (N: an integer of 2 or more) linear members formed of an elastic body and formed in a linear rod shape are arranged parallel to each other with a first gap therebetween, and are adjacent to each other on the same side of the N linear members. Using a substantially U-shaped or substantially S-shaped or substantially wave-shaped external force responsive body formed by alternately joining two end portions with (N-1) joining members,
The outermost linear member that is the outermost linear member among the linear members is the beam-shaped member, and is the end of another linear member facing the first end from near the first end that is the tip of the inner surface thereof. A protruding portion is protruded toward the vicinity of the second end or from the vicinity of the second end toward the vicinity of the first end, and a first action portion provided near the tip of the protruding portion. A second gap is provided as the structure conversion gap between the second end or the second end provided near the first end at a location facing the first end;
A strain gauge is attached to the surface of the external force responsive body,
A load is applied to substantially the center of the outer surface of the outermost linear member so as to be on the same axis and have opposite directions. If the load is less than a first load value, the first action portion and the second action portion Are deformed so as to approach each other, and when the load becomes equal to the first load value, the first action portion and the second action portion contact each other, and the load exceeds the first load value. In such a case, the strain gauge is configured such that substantially the center of the outermost linear member and adjacent linear members are deformed so as to approach each other when the first operating portion is in contact with the second operating portion, and the strain gauge Measuring the value of the load from the output of
It is characterized by.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
(1) First embodiment
FIG. 1 is a diagram showing a configuration of a load measuring device according to a first embodiment of the present invention. As shown in FIG. 1, the load measuring device 1A includes a first linear member 11A, a second linear member 12A, a joining member 13A, a strain gauge 80, and loading spindles 23A and 24A. I have.
[0022]
The first straight member 11A is made of an elastic body such as steel, and is formed in a straight bar shape. The second straight member 12A is made of an elastic material such as steel and is formed in a straight bar shape. The first straight member 11A and the second straight member 12A are arranged so as to be parallel to each other, and a first gap 19A is provided between the two.
[0023]
In addition, two ends of the first straight member 11A and the second straight member 12A that are adjacent on the same side are connected to each other, and the left end of the first straight member 11A in FIG. 1 and the left end of the second straight member 12A. Are joined by a joining member 13A. The joining member 13A is made of an elastic body such as steel and is formed in an arc shape. Here, the first linear member 11A, the second linear member 12A, and the joining member 13A constitute an external force responding body 10A having a substantially U-shape as a whole.
[0024]
From the vicinity of the first end 14A, which is the tip of the inner surface of the second straight member 12A, toward the vicinity of the second end 15A, which is the end of the first straight member 11A, which is the straight member facing the first end 14A, A protruding portion 16A is provided. In the case of FIG. 1, the second linear member 12A corresponds to the outermost linear member and the beam-shaped member in the claims.
[0025]
The surface 17A near the tip of the protruding portion 16A constitutes a first operating portion. Also, the surface 18A at a location near the second end 15A and facing the first action portion 17A constitutes a second action portion. A second gap 20A is provided between the first action portion 17A and the second action portion 18A. The second gap 20A corresponds to a gap for structural conversion in the claims.
[0026]
Further, a strain gauge 80 is attached to the outer surface of the joining member 13A. In this case, the joining member 13A corresponds to the outermost joining member in the claims. The strain gauge 80 has the same configuration and operation as those of the above-described conventional strain gauge.
[0027]
A female screw hole 21A is formed substantially at the center of the outer surface of the first linear member 11A, and a male screw on the outer periphery of the loading spindle 23A is screwed into the female screw hole 21A. A female screw hole 22A is formed substantially at the center of the outer surface of the second linear member 12A, and a male screw on the outer periphery of the loading spindle 24A is screwed into the female screw hole 22A. With such a configuration, the loading spindle 23A is screwed into the female screw hole 21A and attached, and the loading spindle 24A is screwed into the female screw hole 22A and attached.
[0028]
Next, a method for measuring a load using the load measuring device 1A having the above-described configuration will be described with reference to FIGS. 1, 2, and 3. FIG.
[0029]
First, a load that is on the same axis and has the opposite direction, for example, a compressive load P shown in FIGS. 1 to 3 is applied to each of the loading spindles 23A and 24A.
[0030]
In this case, as long as the compression load P is small and the compression load is smaller than a certain value (hereinafter, referred to as a “first load value”), as shown in FIG. The first action portion 17A and the second action portion 18A are deformed so as to approach each other. In this case, the second linear member 12A, which is the outermost linear member, and the first linear member 11A, which is the adjacent linear member, are deformed so as to approach each other.
[0031]
Thereafter, when the compression load P is further increased, when the compression load P reaches the first load value, the deformation amount becomes equal to the value of the second gap 20A. Therefore, as shown in FIG. 2, the first action portion 17A and the second action portion 18A come into contact with each other.
[0032]
After that, when the compressive load P is further increased beyond the first load value, as shown in FIG. 3, the second straight line is maintained while the first operating portion 17A is in contact with the second operating portion 18A. The approximate center of the member 12A and the adjacent first linear member 11A are deformed so as to approach each other.
[0033]
At this time, the strain gauge 80 constitutes the aforementioned Wheatstone bridge circuit or the like (not shown), and is connected to a power supply (not shown) and has an output terminal (not shown) having a voltmeter (not shown). ), And a voltage corresponding to the distortion is measured. The distortion is calculated from the change in the voltage.
[0034]
Since the structure of the external force responding body 10A is known as shown in FIGS. 1 to 3, the relationship between the compressive load P and the strain can be obtained in advance by numerical calculation. Alternatively, a load having a known value may be applied, and a preliminary test for measuring the strain in this case may be performed. Thus, the compression load P can be measured only by the output from the strain gauge 80.
[0035]
Next, the operation principle of the load measuring device 1A according to the first embodiment will be described with reference to FIG.
[0036]
It can be seen that the external force responding body 10A in the load measuring device 1A shown in FIGS. 1 to 3 becomes two beam-shaped members when cut at substantially the center of the joining member 13A at the left end in FIGS. From this, the structural mechanical model in the state of FIG. 1 (the state in which the first action portion 17A and the second action portion 18A are not in contact with each other) is a so-called “cantilever” as shown in FIG. Are connected in a mirror-symmetric state. That is, the first linear member 11A in FIG. 1 is fixed at the left end, and a structural mechanical model (hereinafter, referred to as “first structural model”) in which the load P acts on substantially the center of the beam whose right end is free. ). Similarly, the second linear member 12A is also fixed at the left end, and a structural mechanical model (hereinafter, referred to as “first structural model”) in which a load P acts on the substantially central point C of the beam whose right end is free. ").)).
[0037]
In this case, the bending moment M at the fixed end A of the cantilever beam AB in FIG. A1 If the load is P, the loading position is approximately the center of the beam, and the distance from the fixed end is a, then M A1 = P × a (unit: Nm).
[0038]
On the other hand, the structural mechanical model in the state of FIG. 2 and FIG. 3 (the state after the first action part 17A and the second action part 18A are in contact with each other) has a left end as shown in FIG. It can be considered that two beams that are fixed and whose right end is simply supported are connected in a mirror-symmetric state. That is, the first linear member 11A in FIGS. 2 and 3 is a structural mechanical model (hereinafter, referred to as a load) in which a load P acts on a substantially central point C ′ of a beam whose right end is fixed and whose right end is simply supported. , "Second structure model"). Similarly, the second linear member 12A is also fixed at the left end, and a structural mechanical model (hereinafter, referred to as “secondary”) in which the load P acts on the substantially central point C ′ of the beam whose right end is in the simple support state. Structural model ").
[0039]
In this case, the bending moment M at the fixed end A 'of the "semi-fixed / semi-simple support beam"A'B' in FIG. A2 If the load is P, the loading position is approximately the center of the beam, and the distance from the fixed end is a, then M A2 = 3 × P × a / 8 = 0.375 × P × a (unit: Nm). That is, the fixed end moment M in this case A2 Is M A1 It is about 0.4 times of.
[0040]
As is clear from this, the external force responsive body 10A of the load measuring device 1A has a structural mechanical model at a stage before the first operating portion 17A and the second operating portion 18A come into contact with each other and at a stage after the contact. Is changed to a different one, and accordingly, the bending moment at the fixed end (the left end in the drawings in FIGS. 1 to 3) is reduced to 40% or less of that before the contact. The value of the strain is proportional to the value of the bending moment. Therefore, the output value from the strain gauge 80 of the load measuring device 1A is reduced by about 60% before and after the first and second operating portions 17A and 18A come into contact with each other. This means that in the load measuring device 1A, when the value of the compressive load P reaches the first load value, the "sensitivity" for measuring the strain is reduced to 0.4 times with a load higher than the first load value. ing.
[0041]
According to such a principle, the structure of the external force responding body 10A in the load measuring device 1A of the present embodiment has a free structure in the first structural model in which a load is loaded at substantially the center of a beam having one end fixed and the other end free. This is substantially equivalent to a mechanism in which an immovable portion is provided below or above the end, and a second gap 20A is provided between the immovable portion and the free end. Therefore, when the load exceeds a certain load value (first load value), the amount of deformation of the free end becomes equal to the value of the second gap 20A, and the free end comes into contact with the immobile portion. Therefore, when the load is equal to or more than the first load value, the structural system of the external force responsive body 10A is converted into a second structural model in which a load is loaded at one end and the other end is loaded substantially at the center of a simply supported beam. You. In this case, the bending moment and the strain near the fixed end A ′ of the structural system after the structural conversion are smaller than those of the structural system before the structural conversion. For this reason, there is an advantage that the sensitivity of the strain measurement can be reduced and the load measurement can be performed in a wide dynamic range from a small load to a large load. In the beam structure model of FIG. 4A, the load P when the deflection of the free end B of the beam AB is equal to the value of the first gap 20A is the load when the structural model is converted into the second structural model. It becomes P. Further, in the second structural model of FIG. 4B, the maximum value of the load P that can be measured is, assuming that the stress due to the load P is equal to or less than the strength of the beam A′B ′, the center point C of the beam A′B ′. ′ Becomes equal to the value of the first gap 19A, and becomes a load when the lower surface of the center point C ′ of the beam contacts the floor of the lower immovable part.
[0042]
In addition, instead of the above-mentioned protruding portion 16A, it is an end of the second linear member 12A which is a linear member facing the second end 15A from near the second end 15A which is the front end of the inner surface of the first linear member 11A. A protrusion (not shown) protruding toward the vicinity of the first end 14A may be provided. In this case, the first linear member 11A corresponds to the outermost linear member and the beam-like member in the claims.
[0043]
In this case, a surface near the tip of another protruding portion projecting from the second end 15A becomes another first action portion. In addition, a surface of a portion near the first end 14A and facing the other first action portion serves as another second action portion. Further, a gap disposed between the other first action section and the other second action section is a second gap.
[0044]
(2) Second embodiment
The present invention can be realized by a configuration other than the first embodiment described above. FIG. 5 is a diagram illustrating a configuration of a load measuring device according to a second embodiment of the present invention. FIG. 6 is a diagram illustrating a state in which the first operating portion and the second operating portion are in contact with each other due to a load in the load measuring device according to the second embodiment.
[0045]
As shown in FIG. 5, the load measuring device 1B includes a first linear member 11B, a second linear member 12B, a joining member 13B, a strain gauge 80, and loading spindles 23B and 24B. I have. In the first embodiment 1A of FIGS. 1 to 3 and the second embodiment 1B of FIGS. 5 and 6, the vertical relationship between the first linear member, the second linear member, and the loading spindle is reversed.
[0046]
The first straight member 11B is made of an elastic body such as steel, and is formed in a straight bar shape. The second straight member 12B is made of an elastic body such as steel and is formed in a straight bar shape. The first straight member 11B and the second straight member 12B are arranged so as to be parallel to each other, and a first gap 19B is provided between the two.
[0047]
Further, of the first linear member 11B and the second linear member 12B, two adjacent ends on the same side are connected to each other, and the left end of the first linear member 11B in FIG. 5 and the left end of the second linear member 12B. Are joined by a joining member 13B. The joining member 13B is made of an elastic body such as steel and is formed in an arc shape. Here, the 1st linear member 11B, the 2nd linear member 12B, and the joining member 13B comprise the external force responding body 10B in which the whole becomes substantially U-shaped.
[0048]
From the vicinity of the first end 14B which is the tip of the inner surface of the second straight member 12B, toward the vicinity of the second end 15B which is the end of the first straight member 11B which is the straight member facing the first end 14B. A protruding portion 16B is provided. The protrusion 16B is formed in a substantially L shape. In the case of FIG. 5, the second straight member 12B corresponds to the outermost straight member and the beam-like member in the claims.
[0049]
Also, the vicinity of the tip of the substantially L-shaped projection 16B is a bent end 17B bent at a substantially right angle toward the left side in FIG. 5 so as to go around the lower part of the first linear member 11B. The part 17B constitutes a first action part. In addition, the surface 18B at a position near the second end 15B and opposite to the first action portion 17B constitutes a second action portion. The second operating portion 18B can be locked by the first operating portion 17B, and the second operating portion 18B is a locked portion with respect to the first operating portion 17B. A second gap 20B is provided between the first action portion 17B and the second action portion 18B. The second gap 20B corresponds to a gap for structure conversion in the claims.
[0050]
Further, a strain gauge 80 is attached to an outer surface of the joining member 13B. In this case, the joining member 13B corresponds to the outermost joining member in the claims. The strain gauge 80 has the same configuration and operation as those of the above-described conventional strain gauge.
[0051]
A female screw hole 21B is formed substantially at the center of the outer surface of the first linear member 11B, and a male screw on the outer periphery of the loading spindle 23B is screwed into the female screw hole 21B. A female screw hole 22B is formed substantially at the center of the outer surface of the second linear member 12B, and a male screw on the outer periphery of the loading spindle 24B is screwed into the female screw hole 22B. With such a configuration, the loading spindle 23B is screwed into the female screw hole 21B and attached, and the loading spindle 24B is screwed into the female screw hole 22B and attached.
[0052]
Next, a method of measuring a load using the load measuring device 1B having the above-described configuration will be described with reference to FIGS.
[0053]
First, a load that is on the same axis and has the opposite direction, for example, a tensile load T shown in FIGS. 5 and 6 is applied to each of the loading spindles 23B and 24B.
[0054]
In this case, as long as the tensile load T is small and the compressive load is less than a certain value (hereinafter, referred to as a “first load value”), as shown in FIG. The first action portion 17B and the second action portion 18B are deformed so as to approach each other. In this case, the second linear member 12B, which is the outermost linear member, and the first linear member 11B, which is the adjacent linear member, are deformed so as to be separated from each other.
[0055]
Thereafter, when the compressive load P is further increased, when the tensile load T reaches the first load value, the deformation amount becomes equal to the value of the second gap 20B. Therefore, as shown in FIG. 2, the first action portion 17B and the second action portion 18B come into contact with each other.
[0056]
After that, when the tensile load T is further increased beyond the first load value, the second operating portion 18B and the second operating portion 18B are kept in contact with each other, though not shown, while not shown. The approximate center of the linear member 12B and the adjacent first linear member 11B are deformed so as to be separated from each other.
[0057]
At this time, the strain gauge 80 constitutes the aforementioned Wheatstone bridge circuit or the like (not shown), and is connected to a power supply (not shown) and has an output terminal (not shown) having a voltmeter (not shown). ), And a voltage corresponding to the distortion is measured. The distortion is calculated from the change in the voltage.
[0058]
Since the structure of the external force responding body 10B is known as shown in FIGS. 5 and 6, the relationship between the tensile load T and the strain can be obtained in advance by numerical calculation. Alternatively, a load having a known value may be applied, and a preliminary test for measuring the strain in this case may be performed. Thus, the tensile load T can be measured only by the output from the strain gauge 80.
[0059]
The operation principle of the load measuring device 1B of the second embodiment is substantially equivalent to a structural mechanical model in which a reverse (upward) load T acts on substantially the center of a beam instead of the load P in FIG. . Therefore, the bending moment and the strain show the same behavior in absolute value, except that the positive and negative signs are reversed.
[0060]
That is, it can be seen that the external force responding body 10B in the load measuring device 1B shown in FIGS. 5 and 6 becomes two beam-shaped members when cut at substantially the center of the joining member 13B at the left end in FIGS. From this, the structural mechanical model in the state of FIG. 5 (the state in which the first action portion 17B and the second action portion 18B are not in contact with each other) is a so-called “cantilever” as shown in FIG. Are connected in a mirror-symmetric state. That is, the first linear member 11B in FIG. 5 is fixed at the left end, and has a structure in which a load T (not shown) in the direction opposite to the load P acts on substantially the center of the beam whose free end is in the right end. This is considered to be substantially equivalent to a mechanical model (hereinafter, referred to as “first structural model”). Similarly, the second linear member 12B is also fixed at the left end, and a structural mechanical model (hereinafter, referred to as a "first") in which a load T (not shown) acts on substantially the center of a beam whose right end is in a free state. One structural model ”).
[0061]
In this case, the bending moment M at the fixed end of the cantilever AB in FIG. A1 If the load is T, the loading position is approximately the center of the beam, and the distance from the fixed end is a, then M A1 = −T × a (unit: Nm).
[0062]
On the other hand, the structural mechanical model in the state shown in FIG. 6 (the state after the first action part 17B and the second action part 18B are in contact with each other) is fixed at the left end as shown in FIG. It can be considered that two beams whose right ends are simply supported are connected in mirror symmetry. That is, the first straight member 11B in FIG. 6 is fixed at the left end, and the right end is in the simple support state (the immovable part of the fulcrum is above the fulcrum, which is opposite to that of FIG. 4B). Is considered to be substantially equivalent to a structural mechanical model (hereinafter, referred to as “second structural model”) in which a load T (not shown) in the direction opposite to the load P acts at substantially the center. Similarly, the second linear member 12B is also fixed at the left end, and the right end is in the simple support state (the immovable part of the fulcrum is above the fulcrum, which is the opposite of FIG. 4B). This is considered to be substantially equivalent to a structural mechanical model in which a load T (not shown) acts at substantially the center (hereinafter, referred to as “second structural model”).
[0063]
In this case, the bending moment M at the fixed end of the “semi-fixed / semi-simple support beam” B′B ′ in FIG. A2 If the load is T, the loading position is approximately the center of the beam, and the distance from the fixed end is a, then M A2 = −3 × T × a / 8 = −0.375 × T × a (unit: Nm). That is, the fixed end moment M in this case A2 Is M A1 It is about 0.4 times of.
[0064]
As is apparent from this, the external force responsive body 10B of the load measuring device 1B has a structural mechanical model in a stage before the first acting portion 17B and the second acting portion 18B come into contact with each other and in a stage after the contact. Is changed to a different one, and accordingly, the bending moment at the fixed end (the left end in the drawings in FIGS. 5 and 6) is reduced to 40% or less before contact. The value of the strain is proportional to the value of the bending moment. Therefore, the output value from the strain gauge 80 of the load measuring device 1B is reduced by about 60% before and after the first action portion 17B and the second action portion 18B contact each other. This means that, in the load measuring device 1B, when the value of the tensile load T reaches the first load value, the “sensitivity” for measuring the strain is reduced to 0.4 times with a load higher than the first load value. ing.
[0065]
According to such a principle, the structure of the external force responding body 10B in the load measuring device 1B of the present embodiment has a free structure in the first structural model in which a load is loaded at substantially the center of a beam having one end fixed and the other end free. This is substantially equivalent to a mechanism in which an immobile portion is provided above the end, and a second gap 20B is provided between the immobile portion and the free end. Therefore, when the load exceeds a certain load value (first load value), the deformation amount of the free end becomes equal to the value of the second gap 20B, and the free end contacts the upper immovable portion. Therefore, when the load is equal to or greater than the first load value, the structural system of the external force responsive body 10B is converted into a second structural model in which the load is loaded at one end and the load is placed at approximately the center of the simply supported beam. You. In this case, the bending moment and the strain near the fixed end of the structural system after the structural conversion are smaller than those of the structural system before the structural conversion. For this reason, there is an advantage that the sensitivity of the strain measurement can be reduced and the load measurement can be performed in a wide dynamic range from a small load to a large load. In the beam structure model of FIG. 4A, the load P when the deflection of the free end B of the beam AB is equal to the value of the first gap 20B is the load when the structural model is converted into the second structural model. It becomes P. In addition, in the above-described second structural model, the maximum value of the load T that can be measured is, assuming that the stress due to the load T is equal to or less than the strength of the beam, the deflection of the center point C ′ of the beam A′B ′ is the first gap 19B. And the load when the upper surface of the center point of the beam contacts the ceiling of the upper immovable part.
[0066]
In addition, instead of the above-mentioned protruding portion 16B, it is an end of the second linear member 12B which is a linear member facing the second end 15B from near the second end 15B which is the tip of the inner surface of the first linear member 11B. A substantially L-shaped protrusion (not shown) protruding toward the vicinity of the first end 14B may be provided. In this case, the first straight member 11B corresponds to the outermost straight member and the beam-like member in the claims.
[0067]
In this case, a bent end bent from the vicinity of the distal end of another substantially L-shaped projecting portion projecting from the second end 15B becomes another first action portion. In addition, a surface of a portion near the first end 14B and facing the other first action portion serves as another second action portion. Further, a gap disposed between the other first action section and the other second action section is a second gap.
[0068]
(3) Third embodiment
The present invention can be realized by a configuration other than the first and second embodiments. FIG. 7 is a diagram illustrating a configuration of a load measuring device according to a third embodiment of the present invention.
[0069]
As shown in FIG. 7, the load measuring device 1C includes a first linear member 11C, a second linear member 12C, a joining member 13C, a strain gauge 80, and loading spindles 23C and 24C. I have. In the first embodiment 1A shown in FIGS. 1 to 3 and the third embodiment 1C shown in FIG. 7, the vertical relationship between the first linear member, the second linear member, and the loading spindle is reversed.
[0070]
The first straight member 11C is made of an elastic body such as steel and is formed in a straight bar shape. The second straight member 12C is made of an elastic body such as steel and is formed in a straight bar shape. The first straight member 11C and the second straight member 12C are arranged so as to be parallel to each other, and a first gap 19C is provided between the two.
[0071]
Further, two ends of the first straight member 11C and the second straight member 12C which are adjacent on the same side are connected to each other, and the left end of the first straight member 11C and the left end of the second straight member 12C in FIG. Are joined by a joining member 13C. The joining member 13C is made of an elastic body such as steel and is formed in an arc shape. Here, the first linear member 11C, the second linear member 12C, and the joining member 13C constitute an external force responding body 10C that is substantially U-shaped as a whole.
[0072]
From the vicinity of the first end 14C, which is the tip of the inner surface of the second straight member 12C, toward the vicinity of the second end 15C, which is the end of the first straight member 11C, which is the straight member facing the first end 14C, The protrusion 16C1 and the protrusion 16C2 are provided to protrude. The protrusion 16C2 is formed in a substantially L shape. In the case of FIG. 7, the second straight member 12C corresponds to the outermost straight member and the beam-like member in the claims.
[0073]
The surface 17C1 near the tip of the protruding portion 16C1 constitutes a first operating portion. In addition, the surface 18C1 at a position in the vicinity of the second end 15C and opposed to the first action portion 17C1 constitutes a second action portion. A second gap 20C1 is provided between the first action portion 17C1 and the second action portion 18C1. The second gap 20C1 corresponds to a gap for structural conversion in the claims.
[0074]
Further, the vicinity of the distal end of the substantially L-shaped projecting portion 16C2 is a bent end portion 17C2 which is bent substantially rightward toward the left side of FIG. 7 so as to go under the first linear member 11C. The part 17C2 constitutes a first action part. In addition, the surface 18C2 at a location near the second end 15C and facing the first action portion 17C2 constitutes a second action portion. The second operating portion 18C2 can be locked by the first operating portion 17C2, and the second operating portion 18C2 is a locked portion with respect to the first operating portion 17C2. A second gap 20C2 is provided between the first action portion 17C2 and the second action portion 18C2. The second gap 20C2 corresponds to a gap for structure conversion in the claims.
[0075]
Further, a strain gauge 80 is attached to the outer surface of the joining member 13C. In this case, the joining member 13C corresponds to the outermost joining member in the claims. The strain gauge 80 has the same configuration and operation as those of the above-described conventional strain gauge.
[0076]
A female screw hole 21C is formed substantially at the center of the outer surface of the first linear member 11C, and a male screw on the outer periphery of the loading spindle 23C is screwed into the female screw hole 21C. A female screw hole 22C is formed substantially at the center of the outer surface of the second linear member 12C, and a male screw on the outer periphery of the loading spindle 24C is screwed into the female screw hole 22C. With such a configuration, the loading spindle 23C is screwed into the female screw hole 21C and attached, and the loading spindle 24C is screwed into the female screw hole 22C and attached.
[0077]
The load measuring device 1C according to the third embodiment has a configuration in which the load measuring device 1A according to the first embodiment and the load measuring device 1B according to the second embodiment are combined. It has both functions of the load measuring device 1A of the form and the load measuring device 1B of the second embodiment. Therefore, if the load measuring device 1C of the third embodiment is used, both the load measuring method of the load measuring device 1A of the first embodiment and the load measuring method of the load measuring device 1B of the second embodiment are required to be one. It has the advantage that load measurement can be performed with a wide dynamic range from a small load to a large load.
[0078]
(4) Fourth embodiment
The present invention can be realized by a configuration other than the above-described first to third embodiments. FIG. 8 is a diagram showing a configuration of a load measuring device according to a fourth embodiment of the present invention.
[0079]
As shown in FIG. 8, the load measuring device 1D includes a first linear member 11D, a second linear member 12D, a third linear member 33D, joining members 13D1 and 13D2, and two strain gauges 80, 80. And loading spindles 23D and 24D.
[0080]
The first straight member 11D is made of an elastic body such as steel and is formed in a straight bar shape. The second straight member 12D is made of an elastic body such as steel and is formed in a straight bar shape. The third straight member 33D is made of an elastic material such as steel and is formed in a straight bar shape. The first straight member 11D and the second straight member 12D are arranged so as to be parallel to each other, and a first gap 19D1 is provided between the two. The second straight member 12D and the third straight member 33D are arranged so as to be parallel to each other, and a first gap 19D2 is provided between the two.
[0081]
In addition, of the first straight member 11D and the second straight member 12D, two adjacent ends on the same side are connected to each other, and the left end of the first straight member 11D and the left end of the second straight member 12D in FIG. Are joined by a joining member 13D1. The joining member 13D1 is made of an elastic body such as steel, and is formed in an arc shape. Further, two ends of the second straight member 12D and the third straight member 33D that are adjacent on the same side are connected to each other, and the right end of the second straight member 12D in FIG. 8 and the right end of the third straight member 33D. Are joined by a joining member 13D2. The joining member 13D2 is made of an elastic body such as steel and is formed in an arc shape. Here, the first linear member 11D, the second linear member 12D, the joining member 13D1, the third linear member 33D, and the joining member 13D2 constitute an external force responsive body 10D having a substantially S-shape as a whole. I have.
[0082]
From the vicinity of the first end 14D1, which is the tip of the inner surface of the first straight member 11D, toward the vicinity of the second end 15D1, which is the end of the second straight member 12D, which is the straight member facing the first end 14D1, A protruding portion 16D1 is protruded. Further, from the vicinity of the first end 14D2, which is the tip of the inner surface of the third linear member 33D, toward the vicinity of the second end 15D2, which is the end of the second linear member 12D, which is the linear member facing the first end 14D2. Thus, a protruding portion 16D2 is protruded. In the case of FIG. 8, the first straight member 11D and the third straight member 33D correspond to the outermost straight member and the beam-like member in the claims.
[0083]
The surface 17D1 near the tip of the protruding portion 16D1 constitutes a first operating portion. In addition, the surface 18D1 at a position facing the first action portion 17D1 near the second end 15D1 constitutes a second action portion. A second gap 20D1 is provided between the first action portion 17D1 and the second action portion 18D1. The second gap 20D1 corresponds to a gap for structure conversion in the claims.
[0084]
The surface 17D2 near the tip of the protruding portion 16D2 constitutes a first operating portion. In addition, the surface 18D2 at a position near the second end 15D2 and facing the first action portion 17D2 constitutes a second action portion. A second gap 20D2 is provided between the first action portion 17D2 and the second action portion 18D2. The second gap 20D2 corresponds to a gap for structure conversion in the claims.
[0085]
Further, strain gauges 80 are attached to the outer surface of the joining member 13D1 and the outer surface of the joining member 13D2, respectively. In this case, the joining members 13D1 and 13D2 correspond to the outermost joining members in the claims. The strain gauge 80 has the same configuration and operation as those of the above-described conventional strain gauge.
[0086]
A female screw hole 21D is formed substantially at the center of the outer surface of the first linear member 11D, and a male screw on the outer periphery of the loading spindle 23D is screwed into the female screw hole 21D. A female screw hole 22D is formed substantially at the center of the outer surface of the third linear member 33D, and a male screw on the outer periphery of the loading spindle 24D is screwed into the female screw hole 22D. With such a configuration, the loading spindle 23D is screwed into the female screw hole 21D and attached, and the loading spindle 24D is screwed into the female screw hole 22D and attached.
[0087]
The load measuring device 1D of the above-described fourth embodiment is configured such that the ends of three linear members are alternately joined by joining members, so that the external force responding body becomes substantially S-shaped as a whole. The load measuring device 1D according to the fourth embodiment can measure the compression load P based on the same principle as the load measuring device 1A according to the first embodiment. Value) or more, the mechanical action (mechanism) acts to convert the structural system of the external force responsive body 10D, which can reduce the sensitivity of strain measurement, and can be applied over a wide dynamic range from a small load to a large load. It has the advantage that measurements can be made.
[0088]
(5) Fifth embodiment
The present invention can be realized by a configuration other than the above-described first to fourth embodiments. FIG. 9 is a diagram showing a configuration of a load measuring device according to a fifth embodiment of the present invention.
[0089]
As shown in FIG. 9, the load measuring device 1E includes a first linear member 11E, a second linear member 12E, a third linear member 33E, joining members 13E1 and 13E2, and two strain gauges 80, 80. And loading spindles 23E and 24E.
[0090]
The first straight member 11E is made of an elastic body such as steel, and is formed in a straight bar shape. The second straight member 12E is made of an elastic body such as steel, and is formed in a straight rod shape. The third straight member 33E is made of an elastic body such as steel and is formed in a straight bar shape. The first straight member 11E and the second straight member 12E are arranged so as to be parallel to each other, and a first gap 19E1 is provided between the two. The second straight member 12E and the third straight member 33E are arranged so as to be parallel to each other, and a first gap 19E2 is provided between the two.
[0091]
Further, of the first straight member 11E and the second straight member 12E, two adjacent ends on the same side are connected to each other, and the left end of the first straight member 11E and the left end of the second straight member 12E in FIG. Are joined by a joining member 13E1. The joining member 13E1 is made of an elastic body such as steel and is formed in an arc shape. Further, two ends of the second straight member 12E and the third straight member 33E that are adjacent on the same side are connected to each other by the right end of the second straight member 12E in FIG. 9 and the right end of the third straight member 33E. Are joined by a joining member 13E2. The joining member 13E2 is made of an elastic body such as steel, and is formed in an arc shape. Here, the first linear member 11E, the second linear member 12E, the joining member 13E1, the third linear member 33E, and the joining member 13E2 constitute an external force responsive body 10E having a substantially S-shape as a whole. I have.
[0092]
From the vicinity of the first end 14E1, which is the tip of the inner surface of the second straight member 12E, toward the vicinity of the second end 15E1, which is the end of the first straight member 11E, which is the straight member facing the first end 14E1, A protruding portion 16E1 is provided. The protrusion 16E1 is formed in a substantially L shape. Further, from the vicinity of the first end 14E2, which is the tip of the inner surface of the second linear member 12E, toward the vicinity of the second end 15E2, which is the end of the third linear member 33E, which is the linear member facing the first end 14E2. Thus, a protruding portion 16E2 is protruded. The protrusion 16E2 is formed in a substantially L-shape. In the case of FIG. 9, the first straight member 11E and the third straight member 33E correspond to the outermost straight member and the beam-like member in the claims.
[0093]
Also, the vicinity of the tip of the substantially L-shaped projection 16E1 is a bent end 17E1 bent at a substantially right angle toward the left side in FIG. 9 so as to go around the lower part of the first linear member 11E. The part 17E1 constitutes a first action part. In addition, the surface 18E1 at a location near the second end 15E and facing the first action portion 17E1 constitutes a second action portion. The second operating portion 18E1 can be locked by the first operating portion 17E1, and the second operating portion 18E1 is a locked portion with respect to the first operating portion 17E1. A second gap 20E1 is provided between the first action portion 17E1 and the second action portion 18E1. The second gap 20E1 corresponds to a gap for structure conversion in the claims.
[0094]
Also, the vicinity of the distal end of the substantially L-shaped protrusion 16E2 is a bent end 17E2 bent substantially rightward toward the right side in FIG. 9 so as to go to the lower part of the third linear member 33E. The part 17E2 constitutes a first action part. In addition, the surface 18E2 at a position near the second end 15E and facing the first action portion 17E2 constitutes a second action portion. The second operating portion 18E2 can be locked by the first operating portion 17E2, and the second operating portion 18E2 is a locked portion with respect to the first operating portion 17E2. A second gap 20E2 is provided between the first action portion 17E2 and the second action portion 18E2. The second gap 20E2 corresponds to a gap for structure conversion in the claims.
[0095]
Further, strain gauges 80 are attached to the outer surface of the joining member 13E1 and the outer surface of the joining member 13E2, respectively. In this case, the joining members 13E1 and 13E2 correspond to the outermost joining members in the claims. The strain gauge 80 has the same configuration and operation as those of the above-described conventional strain gauge.
[0096]
A female screw hole 21E is formed substantially at the center of the outer surface of the first linear member 11E, and a male screw on the outer periphery of the loading spindle 23E is screwed into the female screw hole 21E. A female screw hole 22E is formed substantially at the center of the outer surface of the third linear member 33E, and a male screw on the outer periphery of the loading spindle 24E is screwed into the female screw hole 22E. With such a configuration, the loading spindle 23E is screwed into the female screw hole 21E and attached, and the loading spindle 24E is screwed into the female screw hole 22E and attached.
[0097]
The load measuring device 1E according to the fifth embodiment described above is configured such that the ends of three linear members are alternately joined by joining members, so that the external force responding body becomes substantially S-shaped as a whole. The load measuring device 1E according to the fifth embodiment can measure the tensile load T based on the same principle as the load measuring device 1B according to the second embodiment. Value) or more, a mechanical action (mechanism) acts to convert the structural system of the external force responsive body 10E, thereby lowering the sensitivity of strain measurement, and applying a wide dynamic range from a small load to a large load. It has the advantage that measurements can be made.
[0098]
(6) Sixth embodiment
The present invention can be realized by a configuration other than the above-described first to fifth embodiments. FIG. 10 is a diagram showing a configuration of a load measuring device according to a sixth embodiment of the present invention.
[0099]
As shown in FIG. 10, the load measuring device 1F includes a first linear member 11F, a second linear member 12F, a third linear member 33F, joining members 13F1 and 13F2, and two strain gauges 80, 80. And loading spindles 23F and 24F.
[0100]
The first straight member 11F is made of an elastic body such as steel, and is formed in a straight bar shape. The second straight member 12F is made of an elastic body such as steel and is formed in a straight bar shape. The third straight member 33F is made of an elastic body such as steel and is formed in a straight bar shape. The first straight member 11F and the second straight member 12F are arranged so as to be parallel to each other, and a first gap 19F1 is provided between the two. The second straight member 12F and the third straight member 33F are arranged so as to be parallel to each other, and a first gap 19F2 is provided between the two.
[0101]
Further, of the first linear member 11F and the second linear member 12F, two adjacent ends on the same side are connected to each other, and the left end of the first linear member 11F and the left side of the second linear member 12F in FIG. Are joined by a joining member 13F1. The joining member 13F1 is made of an elastic body such as steel and is formed in an arc shape. In addition, two ends of the second straight member 12F and the third straight member 33F that are adjacent on the same side are connected to each other, and the right end of the second straight member 12F in FIG. 10 and the right end of the third straight member 33F. Are joined by a joining member 13F2. The joining member 13F2 is made of an elastic body such as steel, and is formed in an arc shape. Here, the first linear member 11F, the second linear member 12F, the joining member 13F1, the third linear member 33F, and the joining member 13F2 constitute an external force responsive body 10F having a substantially S-shape as a whole. I have.
[0102]
From the vicinity of the first end 14F1, which is the tip of the inner surface of the second linear member 12F, toward the vicinity of the second end 15F1, which is the end of the first linear member 11F, which is the linear member facing the first end 14F1, A protruding portion 16F11 and a protruding portion 16F12 are provided. The protrusion 16F12 is formed in a substantially L shape. Further, from the vicinity of the first end 14F2, which is the tip of the inner surface of the second linear member 12F, toward the vicinity of the second end 15F2, which is the end of the third linear member 33F, which is the linear member facing the first end 14F2. Thus, a protrusion 16F21 and a protrusion 16F22 are provided to protrude. The protrusion 16F22 is formed in a substantially L shape. In the case of FIG. 10, the first straight member 11F and the third straight member 33F correspond to the outermost straight member and the beam-like member in the claims.
[0103]
The surface 17F11 near the tip of the protruding portion 16F11 constitutes a first operating portion. In addition, the surface 18F11 at a location near the second end 15F1 and facing the first action portion 17F11 constitutes a second action portion. A second gap 20F11 is provided between the first action portion 17F11 and the second action portion 18F11. The second gap 20F11 corresponds to a gap for structure conversion in the claims.
[0104]
Further, the vicinity of the tip of the substantially L-shaped protrusion 16F12 is a bent end 17F12 bent at a substantially right angle toward the left side of FIG. 10 so as to go around the lower part of the first linear member 11F. The section 17F12 constitutes a first action section. In addition, the surface 18F12 at a position near the second end 15F1 and facing the first action portion 17F12 constitutes a second action portion. The second action portion 18F12 can be locked by the first action portion 17F12, and the second action portion 18F12 is a locked portion with respect to the first action portion 17F12. A second gap 20F12 is provided between the first action portion 17F12 and the second action portion 18F12. The second gap 20F12 corresponds to a gap for structure conversion in the claims.
[0105]
The surface 17F21 near the tip of the protruding portion 16F21 constitutes a first operating portion. In addition, the surface 18F21 at a location near the second end 15F2 and facing the first action portion 17F21 constitutes a second action portion. A second gap 20F21 is provided between the first action portion 17F21 and the second action portion 18F21. The second gap 20F21 corresponds to a gap for structure conversion in the claims.
[0106]
Further, the vicinity of the tip of the substantially L-shaped protrusion 16F22 is a bent end 17F22 bent substantially rightward toward the right side in FIG. 10 so as to wrap around the lower part of the third linear member 33F. The part 17F22 constitutes a first action part. In addition, the surface 18F22 at a location near the second end 15F2 and facing the first action portion 17F22 forms a second action portion. The second operating portion 18F22 can be locked by the first operating portion 17F22, and the second operating portion 18F22 is a locked portion with respect to the first operating portion 17F22. A second gap 20F22 is provided between the first action portion 17F22 and the second action portion 18F22. The second gap 20F22 corresponds to a gap for structure conversion in the claims.
[0107]
Strain gauges 80 are attached to the outer surface of the joining member 13F1 and the outer surface of the joining member 13F2, respectively. In this case, the joining members 13F1 and 13F2 correspond to the outermost joining members in the claims. The strain gauge 80 has the same configuration and operation as those of the above-described conventional strain gauge.
[0108]
A female screw hole 21F is formed substantially at the center of the outer surface of the first linear member 11F, and a male screw on the outer periphery of the loading spindle 23F is screwed into the female screw hole 21F. A female screw hole 22F is formed substantially at the center of the outer surface of the third linear member 33F, and a male screw on the outer periphery of the loading spindle 24F is screwed into the female screw hole 22F. With such a configuration, the loading spindle 23F is screwed into the female screw hole 21F and attached, and the loading spindle 24F is screwed into the female screw hole 22F and attached.
[0109]
The load measuring device 1F according to the sixth embodiment described above is configured such that the ends of three linear members are alternately joined by joining members, so that the external force responding body becomes substantially S-shaped as a whole. The load measuring device 1F according to the sixth embodiment can measure both the compressive load P and the tensile load T by the same principle as the load measuring device 1C according to the second embodiment. When the load T exceeds a certain load value (first load value), a mechanical action (mechanism) works to convert the structural system of the external force responsive body 10F, thereby lowering the sensitivity of strain measurement, and There is an advantage that load measurement can be performed in a wide dynamic range up to a large load.
[0110]
Note that the present invention is not limited to the above embodiments. Each of the above-described embodiments and examples is an exemplification, and any of those having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect can be used. Even so, they are included in the technical scope of the present invention.
[0111]
For example, in each of the above embodiments, an arc-shaped member has been described as an example of a joining member. However, the present invention is not limited to this, and the joining member joins two adjacent linear members. As long as it is possible, it may be a linear member. Therefore, the external force responding body as a whole may have a substantially U-shaped configuration in addition to a substantially U-shaped configuration. Alternatively, in addition to the substantially S-shaped configuration, the external force responding body as a whole may have a substantially S-shaped configuration in which a corner portion is substantially a right angle. Alternatively, the external force responding body as a whole may have a substantially wavy configuration in which the corners are smooth, or a substantially right-angled corner.
[0112]
In the above-described embodiment, the external force responding member has a substantially U-shape as a whole with two linear members and one joining member, and a substantially S-shaped as a whole due to three linear members and two joining members. Although the present invention has been described by way of example, the present invention is not limited to this. The external force responsive body has another configuration, for example, N linear members (N: an integer of 2 or more) and a joining member (N− 1) The shape may be substantially corrugated as a whole. In this case, the external force responsive body is formed by arranging N (N: an integer of 2 or more) linear members formed in a linear rod shape with a first gap disposed in parallel with each other. Of these, an external force responsive body having a substantially U-shape, a substantially S-shape, or a substantially wavy shape formed by alternately joining two end portions adjacent to each other on the same side with (N-1) joining members, From the vicinity of the first end which is the tip of the inner surface of the outermost straight member which is the outermost straight member of the straight members to the vicinity of the second end which is the end of another straight member facing the first end. A projecting portion protruding toward the first end from the vicinity of the second end to the vicinity of the first end, a first operating portion provided near a tip of the projecting portion, and the second end. Alternatively, a second action portion is provided between the first action portion and a second action portion provided near the first end. So that the gap is provided.
[0113]
Further, in each of the above embodiments, the example in which the load is loaded by the loading spindle has been described, but the present invention is not limited to this, and the loading method may be another method. For example, a method of fixing the spindle to the linear member with a bolt may be used. In the case of a compressive load, the load can be applied only by inserting a spindle-shaped member into the recess.
[0114]
According to each of the above embodiments, the measurement of the compression load and the tension load is possible. For the shearing force, for example, the bottom side of the rectangular member may be fixed, and a compressive load or a tensile load may be applied to the upper side as a horizontal force. The torsional moment may be fixed so that the shaft does not rotate, and a compressive load or a tensile load may be applied to a predetermined portion of the shaft such that the moment is around the center line of the shaft. Therefore, by applying the compression load measurement or the tensile load measurement described in each of the above embodiments, the shearing force and the torsional moment can be measured using the load measuring device or the load measuring method of the present invention.
[0115]
Note that the first load value and the maximum measured load value as a whole in the above-described load measuring device are the material (strength, elastic modulus, etc.) of each member, the dimensions of each member (member length, cross-sectional area, cross-section secondary). A desired value can be obtained by appropriately setting the value of the first gap, the value of the second gap, and the like.
[0116]
According to the principle of the present invention described above, the present invention can be realized by a structure other than the above-described embodiment. That is, as shown in FIG. 11A, one end (fixed end 43G) is made of an elastic body such as steel, and one end (fixed end 43G) is fixed by a stationary portion 45G made of a firm floor or wall, and the other end 44G is in a free state. The compressive load P is loaded substantially at the center of the bent beam-shaped member 41G, and an immovable portion 46G is provided below the free end 44G, and the structure conversion is performed between the immovable portion 46G and the free end 44G. The external force responding body 10G may be configured by providing the use gap 47G, and the strain gauge 80 may be attached to a surface near the fixed end 43G of the external force responding body 10G. With this configuration, when the load P is less than the first load value, the free end 44G is deformed so as to approach the immobile portion 46G, and when the compression load P becomes equal to the first load value, the free end 44G is free. When the end 44G contacts the immovable portion 46G and the compression load P exceeds the first load value, the approximate center of the beam 41G approaches the immovable portion 48G with the free end 44G contacting the immovable portion 46G. Thus, the value of the compression load P can be measured from the output of the strain gauge 80.
[0117]
Further, the present invention can be realized by a structure other than the above-described embodiment. That is, as shown in FIG. 11 (B), one end (fixed end 43H) is made of an elastic body such as steel, and one end (fixed end 43H) is fixed by a stationary portion 45H made of a firm floor or wall, and the other end 44H is in a free state. The compressive load P is loaded substantially at the center of the linear beam-shaped member 41H, and an immovable portion 46H is provided below the free end 44H, and the structure conversion is performed between the immovable portion 46H and the free end 44H. The external force responding body 10H may be configured by providing the use gap 47H, and the strain gauge 80 may be attached to a surface near the fixed end 43H of the external force responding body 10H. With this configuration, when the compression load P is less than the first load value, the free end 44H is deformed so as to approach the immobile portion 46H, and when the compression load P becomes equal to the first load value, When the free end 44H contacts the immovable portion 46H and the compression load P exceeds the first load value, the approximate center of the beam 41H approaches the immovable portion 48H with the free end 44H in contact with the immovable portion 46H. And the value of the compression load P can be measured from the output of the strain gauge 80.
[0118]
Further, the present invention can be realized by a structure other than the above-described embodiment. That is, as shown in FIG. 11 (C), one end (fixed end 43J) is made of an elastic body such as steel, and one end (fixed end 43J) is fixed by a stationary portion 45J made of a firm floor or wall, and the other end 44J is in a free state. A tensile load T is loaded substantially at the center of the bent beam-shaped beam member 41J, and an immovable portion 46J is provided above the free end 44J, and the structural conversion is performed between the immovable portion 46J and the free end 44J. The external force responsive body 10J may be configured by providing a gap 47J for use, and the strain gauge 80 may be attached to a surface near the fixed end 43J of the external force responsive body 10J. With this configuration, when the load T is less than the first load value, the free end 44J is deformed so as to approach the immobile portion 46J, and when the tensile load T becomes equal to the first load value, the free end 44J is free. When the end 44J contacts the immovable portion 46J and the tensile load T exceeds the first load value, the approximate center of the beam 41J approaches the immovable portion 48J with the free end 44J in contact with the immovable portion 46J. Thus, the value of the tensile load T can be measured from the output of the strain gauge 80.
[0119]
Further, the present invention can be realized by a structure other than the above-described embodiment. That is, as shown in FIG. 11D, one end (fixed end 43K) is made of an elastic body such as steel, and one end (fixed end 43K) is fixed by a stationary portion 45K made of a firm floor or wall, and the other end 44K is in a free state. The tensile load T is loaded substantially at the center of the linear beam-shaped member 41K, and an immovable portion 46K is provided above the free end 44K, and the structural conversion is performed between the immovable portion 46K and the free end 44K. The external force responsive body 10K may be configured by providing a gap 47K for use, and the strain gauge 80 may be attached to a surface near the fixed end 43K of the external force responsive body 10K. With this configuration, when the tensile load T is less than the first load value, the free end 44K is deformed so as to approach the immovable portion 46K, and when the tensile load T becomes equal to the first load value, When the free end 44K contacts the immovable portion 46K and the tensile load T exceeds the first load value, the approximate center of the beam 41K approaches the immovable portion 48K with the free end 44K in contact with the immovable portion 46K. Thus, the value of the tensile load T can be measured from the output of the strain gauge 80.
[0120]
【The invention's effect】
As described above, according to the load measuring device and the load measuring method according to the present invention, the load is applied to substantially the center of the beam-shaped member made of an elastic body, fixed at one end and free at the other end. An external force responsive body is formed by providing a fixed portion below or above the free end, providing a gap for structural conversion between the fixed portion and the free end, and forming a strain gauge on the surface near the fixed end of the external force responsive body. When the load is less than the first load value, the free end is deformed to approach the immovable part, and when the load becomes equal to the first load value, the free end is immovable. When the load exceeds the first load value, the beam is deformed so that the approximate center of the beam-like member approaches the immovable part with the free end in contact with the immovable part. Can be measured. In this case, there is an advantage that load measurement can be performed in a wide dynamic range from a small load to a large load.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a load measuring device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a state in which a first acting portion and a second acting portion are in contact with each other due to a load in the load measuring device of the first embodiment.
FIG. 3 shows the load measuring device according to the first embodiment, in which the first and second operating portions are deformed so that the substantially central portion of the second linear member and the first linear member come closer to each other in a state where the first and second operating portions are in contact with each other. FIG.
FIG. 4 is a conceptual diagram illustrating the operation principle of the load measuring device according to the present invention.
FIG. 5 is a diagram showing a configuration of a load measuring device according to a second embodiment of the present invention.
FIG. 6 is a diagram showing a state in which a first operating portion and a second operating portion are in contact with each other due to a load in the load measuring device of the second embodiment.
FIG. 7 is a diagram showing a configuration of a load measuring device according to a third embodiment of the present invention.
FIG. 8 is a diagram showing a configuration of a load measuring device according to a fourth embodiment of the present invention.
FIG. 9 is a diagram showing a configuration of a load measuring device according to a fifth embodiment of the present invention.
FIG. 10 is a diagram showing a configuration of a load measuring device according to a sixth embodiment of the present invention.
FIG. 11 is a view showing a configuration of an external force responding body in a load measuring device according to another embodiment of the present invention.
FIG. 12 is a diagram showing a configuration of a conventional strain gauge.
FIG. 13 is a conceptual diagram showing a relationship between stress and strain of an elastic body.
[Explanation of symbols]
1A-1K load measuring device
10A-10K External force responder
11A to 11F First straight member
12A to 12F Second linear member
13A to 13F2 Joining member
14A-14F2 1st end
15A to 15F2 Second end
16A-16F22 Projection
17A-17F22 1st working part
18A to 18F22 2nd action part
19A to 19F2 First gap
20A to 20F22 Second gap
21A-21F First female screw hole
22A to 22F Second female screw hole
23A ~ 23F Loading spindle
24A to 24F Loading spindle
33D-33F Third straight member
41G-41K Beam-shaped member
42G, 42J Straight section
43G-43K Fixed end
44G ~ 44K Free end
45G to 45K immovable part
46G to 46K immovable part
47G-47K Structural conversion gap
48G to 48K immovable part
80 strain gauge
81 gauge base
82 Resistance section
83, 84 Lead wire
P compression load
T tensile load
Z break point

Claims (8)

弾性体からなり、一端で固定され他端が自由状態の梁状部材の略中央に荷重が載荷されるようにし、前記自由端の下方又は上方に不動部を設け、当該不動部と前記自由端との間に構造変換用間隙を設けて外力応答体を構成し、前記外力応答体の前記固定端付近の表面に歪みゲージを貼付し、
前記荷重が第１荷重値未満の場合には前記自由端が前記不動部に接近するように変形し、前記荷重が前記第１荷重値と等しくなった場合には前記自由端が前記不動部に接触し、前記荷重が前記第１荷重値を越えた場合には前記自由端が前記不動部に接触した状態で前記梁状部材の略中央が前記不動部に接近するように変形するように構成し、前記歪みゲージの出力から前記荷重の値を測定すること
を特徴とする荷重測定装置。A load is applied substantially at the center of a beam-shaped member made of an elastic body, fixed at one end and the other end in a free state. An immovable portion is provided below or above the free end, and the immovable portion and the free end are provided. To provide an external force responsive body by providing a gap for structural conversion between, and affix a strain gauge to the surface near the fixed end of the external force responsive body,
When the load is less than the first load value, the free end is deformed so as to approach the immovable portion, and when the load becomes equal to the first load value, the free end is moved to the immovable portion. When the load exceeds the first load value and the free end is in contact with the immovable portion, the center of the beam-shaped member is deformed so as to approach the immovable portion. And a load measuring device for measuring the value of the load from an output of the strain gauge. 弾性体からなり、直線棒状に形成されたＮ（Ｎ：２以上の整数）個の直線部材を互いに平行に第１間隙を配して配置し前記Ｎ個の直線部材のうち同じ側で隣接する２個の端部どうしを（Ｎ−１）個の接合部材で交互に接合して構成される略Ｕ字状又は略Ｓ字状若しくは略波形状の外力応答体を備え、
前記直線部材のうち最も外側となる直線部材である最外直線部材を前記梁状部材としその内面の先端となる第１端の付近から前記第１端に対向する他の直線部材の端である第２端の付近へ向けて、又は前記第２端の付近から前記第１端の付近へ向けて、それぞれ突出部が突設されるとともに、前記突出部の先端付近に設けられる第１作用部と、前記第２端又は前記第１端の付近で前記第１作用部に対向する箇所に設けられる第２作用部との間に、前記構造変換用間隙として第２間隙が設けられ、
前記外力応答体の表面に歪みゲージが貼付され、
前記最外直線部材の外面の略中央の各々に同一軸上となり方向が逆となる荷重を作用させ、前記荷重が第１荷重値未満の場合には前記第１作用部と前記第２作用部が互いに接近するように変形し、前記荷重が前記第１荷重値と等しくなった場合には前記第１作用部と前記第２作用部が互いに接触し、前記荷重が前記第１荷重値を越えた場合には前記第１作用部が前記第２作用部に接触した状態で前記最外直線部材の略中央と、隣接する直線部材が互いに接近するように変形するように構成し、前記歪みゲージの出力から前記荷重の値を測定すること
を特徴とする荷重測定装置。N (N: an integer of 2 or more) linear members formed of an elastic body and formed in a linear rod shape are arranged parallel to each other with a first gap therebetween, and are adjacent to each other on the same side of the N linear members. A substantially U-shaped or substantially S-shaped or substantially wave-shaped external force responsive body formed by alternately joining two end portions with (N-1) joining members;
The outermost linear member that is the outermost linear member among the linear members is the beam-shaped member, and is the end of another linear member facing the first end from near the first end that is the tip of the inner surface thereof. A protruding portion is protruded toward the vicinity of the second end or from the vicinity of the second end toward the vicinity of the first end, and a first action portion provided near the tip of the protruding portion. A second gap is provided as the structure conversion gap between the second end or the second end provided near the first end at a location facing the first end;
A strain gauge is attached to the surface of the external force responsive body,
A load is applied to substantially the center of the outer surface of the outermost linear member so as to be on the same axis and have opposite directions. If the load is less than a first load value, the first action portion and the second action portion Are deformed so as to approach each other, and when the load becomes equal to the first load value, the first action portion and the second action portion contact each other, and the load exceeds the first load value. In such a case, the strain gauge is configured such that substantially the center of the outermost linear member and adjacent linear members are deformed so as to approach each other when the first operating portion is in contact with the second operating portion, and the strain gauge A load measuring device for measuring the value of the load from the output of the load. 請求項１記載の荷重測定装置において、
前記荷重は圧縮荷重であり、前記荷重が前記第１荷重値未満の場合には、前記最外直線部材と、隣接する直線部材が互いに接近するように変形すること
を特徴とする荷重測定装置。The load measuring device according to claim 1,
The load measuring device is characterized in that the load is a compressive load, and when the load is less than the first load value, the outermost linear member and an adjacent linear member are deformed so as to approach each other. 請求項１記載の荷重測定装置において、
前記荷重は引張荷重であり、前記荷重が前記第１荷重値未満の場合には、前記最外直線部材と、隣接する直線部材は互いに離れるように変形すること
を特徴とする荷重測定装置。The load measuring device according to claim 1,
The load measuring device is characterized in that the load is a tensile load, and when the load is less than the first load value, the outermost linear member and an adjacent linear member deform so as to be separated from each other. 請求項４記載の荷重測定装置において、
前記突出部は略Ｌ字状に構成され、前記第１作用部は、前記略Ｌ字状の突出部の屈曲端部であり、
前記第２作用部は、前記第１作用部によって係止可能に設置された被係止部であること
を特徴とする荷重測定装置。The load measuring device according to claim 4,
The protruding portion is formed in a substantially L-shape, and the first operating portion is a bent end of the substantially L-shaped protruding portion,
The load measuring device, wherein the second action section is a locked section installed so as to be locked by the first action section. 請求項１記載の荷重測定装置において、
前記歪みゲージは、
前記最外直線部材と、前記最外直線部材に隣接する直線部材を接合する接合部材である最外接合部材の表面に貼付されること
を特徴とする荷重測定装置。The load measuring device according to claim 1,
The strain gauge is
A load measuring device, which is attached to a surface of an outermost joining member that is a joining member that joins the outermost straight member and a straight member adjacent to the outermost straight member. 弾性体からなり、一端で固定され他端が自由状態の梁状部材の略中央に荷重が載荷されるようにし、前記自由端の下方又は上方に不動部を設け、当該不動部と前記自由端との間に構造変換用間隙を設けて外力応答体を構成し、前記外力応答体の前記固定端付近の表面に歪みゲージを貼付し、
前記荷重が第１荷重値未満の場合には前記自由端が前記不動部に接近するように変形し、前記荷重が前記第１荷重値と等しくなった場合には前記自由端が前記不動部に接触し、前記荷重が前記第１荷重値を越えた場合には前記自由端が前記不動部に接触した状態で前記梁状部材の略中央が前記不動部に接近するように変形するように構成し、前記歪みゲージの出力から前記荷重の値を測定すること
を特徴とする荷重測定方法。A load is applied substantially at the center of a beam-shaped member made of an elastic body, fixed at one end and the other end in a free state. An immovable portion is provided below or above the free end, and the immovable portion and the free end are provided. To provide an external force responsive body by providing a gap for structural conversion between, and affix a strain gauge to the surface near the fixed end of the external force responsive body,
When the load is less than the first load value, the free end is deformed so as to approach the immovable portion, and when the load becomes equal to the first load value, the free end is moved to the immovable portion. When the load exceeds the first load value and the free end is in contact with the immovable portion, the center of the beam-shaped member is deformed so as to approach the immovable portion. And measuring the value of the load from the output of the strain gauge. 弾性体からなり、直線棒状に形成されたＮ（Ｎ：２以上の整数）個の直線部材を互いに平行に第１間隙を配して配置し前記Ｎ個の直線部材のうち同じ側で隣接する２個の端部どうしを（Ｎ−１）個の接合部材で交互に接合して構成される略Ｕ字状又は略Ｓ字状若しくは略波形状の外力応答体を用い、
前記直線部材のうち最も外側となる直線部材である最外直線部材を前記梁状部材としその内面の先端となる第１端の付近から前記第１端に対向する他の直線部材の端である第２端の付近へ向けて、又は前記第２端の付近から前記第１端の付近へ向けて、それぞれ突出部が突設されるとともに、前記突出部の先端付近に設けられる第１作用部と、前記第２端又は前記第１端の付近で前記第１作用部に対向する箇所に設けられる第２作用部との間に、前記構造変換用間隙として第２間隙が設けられ、
前記外力応答体の表面に歪みゲージが貼付され、
前記最外直線部材の外面の略中央の各々に同一軸上となり方向が逆となる荷重を作用させ、前記荷重が第１荷重値未満の場合には前記第１作用部と前記第２作用部が互いに接近するように変形し、前記荷重が前記第１荷重値と等しくなった場合には前記第１作用部と前記第２作用部が互いに接触し、前記荷重が前記第１荷重値を越えた場合には前記第１作用部が前記第２作用部に接触した状態で前記最外直線部材の略中央と、隣接する直線部材が互いに接近するように変形するように構成し、前記歪みゲージの出力から前記荷重の値を測定すること
を特徴とする荷重測定方法。N (N: an integer of 2 or more) linear members formed of an elastic body and formed in a linear rod shape are arranged parallel to each other with a first gap therebetween, and are adjacent to each other on the same side of the N linear members. Using a substantially U-shaped or substantially S-shaped or substantially wave-shaped external force responsive body formed by alternately joining two end portions with (N-1) joining members,
The outermost linear member that is the outermost linear member among the linear members is the beam-shaped member, and is the end of another linear member facing the first end from near the first end that is the tip of the inner surface thereof. A protruding portion is protruded toward the vicinity of the second end or from the vicinity of the second end toward the vicinity of the first end, and a first action portion provided near the tip of the protruding portion. A second gap is provided as the structure conversion gap between the second end or the second end provided near the first end at a location facing the first end;
A strain gauge is attached to the surface of the external force responsive body,
A load is applied to substantially the center of the outer surface of the outermost linear member so as to be on the same axis and have opposite directions. If the load is less than a first load value, the first action portion and the second action portion Are deformed so as to approach each other, and when the load becomes equal to the first load value, the first action portion and the second action portion contact each other, and the load exceeds the first load value. In such a case, the strain gauge is configured such that substantially the center of the outermost linear member and adjacent linear members are deformed so as to approach each other when the first operating portion is in contact with the second operating portion, and the strain gauge Measuring the value of the load from the output of the load.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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