JP2004257948A

JP2004257948A - Pressure sensor

Info

Publication number: JP2004257948A
Application number: JP2003050926A
Authority: JP
Inventors: Seiichi Shimakawa; 清一島川; Tomoyuki Nakamura; 友幸中村
Original assignee: Nagano Keiki Co Ltd
Current assignee: Nagano Keiki Co Ltd
Priority date: 2003-02-27
Filing date: 2003-02-27
Publication date: 2004-09-16

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor capable of reducing a pressure output error, and also reducing its size and weight. SOLUTION: The pressure sensor 10 is provided with a diaphragm 53 detecting pressure and a joint 11 having an introduction piece 11E for introducing pressure into the diaphragm 53. The joint 11 has a screw part 11A for attaching to an attached member 17 and a touch seat plane 11D where the screw part 11A runs against the attached member 17 when screwed into the attached part 17. Around the coupling part 11C coupling with the attached member 17 of the joint 11, and a position not including the touch seat plane 11D, a seal member 18 for sealing pressure is provided. COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、例えばＦＡ（ファクトリーオートメーション）装置等で使用される空気圧や油圧を検出する圧力センサに関する。
【０００２】
【背景技術】
従来、例えばＦＡ装置等の各種機器に取り付けられ、それらの機器で使用される空気圧や油圧を検出する圧力センサが知られている。
この圧力センサの取り付けは、機器等の相手方にねじ込んで行われることが多い（例えば、特許文献１）。
【０００３】
この圧力センサの取り付け構造は、図５，６に示すようになっている。
すなわち、圧力センサ５０は継手５１を備えており、この継手５１は、ねじ部５１Ａとこのねじ部５１Ａより外形が大きなつば部５１Ｂとを有し、このつば部５１Ｂの外形は六角ナット状に形成されている。また、継手５１の上部にはダイアフラム５３が取り付けられ、継手５１のつば部５１Ｂ側一端にはケース部材５２が設けられている。このケース部材５２の内部には、回路基板５４、貫通コンデンサ５５等が配設され、前記ダイアフラム５３もケース部材５２で覆われている。
【０００４】
継手５１のつば部５１Ｂには、継手５１のねじ部５１Ａを機器等の被取付部材５７のねじ部５７Ａにねじ込んだとき、被取付部材５７の取付面表面に突き当たる座面５１Ｄが形成されている。そして、つば部５１Ｂの首下部、つまり、座面５１Ｄとねじ部５７Ａとの交点部には、シール部材であるＯリング５８が装着されている。
【０００５】
Ｏリング５８は、被取付部材５７のねじ部５７Ａの周縁に形成されたＯリング用穴５７Ｂと、継手５１のねじ部５１Ａから凹んで形成された溝５１Ｃとで形成されたＯリング溝５９内に収容されるようになっている。
ここで、それぞれ、Ｏリング用穴５７Ｂの外径がφＡ０、溝５１Ｃの内径がφＢ０、座面５１Ｄの外径がφＣ０としたとき、これらの関係は、φＢ０＜φＡ０＜φＣ０となっている。
【０００６】
このような継手５１を取り付けるには、Ｏリング溝５９内にＯリング５８を装着し、継手５１のねじ部５１Ａを被取付部材５７のねじ部５７Ａにねじ込んで取り付ける。このとき、継手５１のつば部５１Ｂの高さ（厚さ）はＴ０となっており、継手５１の座面５１Ｄからの突出寸法はＨ０となっている。
なお、継手５１の軸心には圧力導入口５１Ｅがあけられている。
【０００７】
【特許文献１】
特開平１０−１５３５０９号公報（従来例；図１０参照）
【０００８】
【発明が解決しようとする課題】
ところで、継手５１を被取付部材５７にねじ込んで取り付ける際、継手５１には、Ｏリング５８用の溝５１Ｃの周縁、つまり、モーメントの起点Ｓ１には、矢印Ａ方向に引っ張り込む力Ｆが発生する。これに対して、つば部５１Ｂにおいて被取付部材５７のＯリング用穴５７Ｂの内周と突き当たる部位、つまり、モーメントの作用点Ｓ２には、矢印Ａとは反対方向に働く矢印Ｂ方向の反力Ｆが生じる。このため、作用点Ｓ２には、起点Ｓ１と作用点Ｓ２との距離の分のモーメント（Ｍ）が発生する。
ねじの締め付けによるモーメント（Ｍ）は、数１に基づいて算出される。
ここで、継手５１の軸中心から応力の発生する作用点Ｓ２までの距離をａとし、継手５１の軸中心から起点Ｓ１までの距離をｂとし、ａとｂとの差（クリアランス）をＬとする。
【０００９】
【数１】

【００１０】
また、この数１に基づいて計算した結果が図７に示されている。
この図７に示すように、クリアランスＬの寸法に応じてモーメントＭがやや比例状態に近い曲線で変化し、クリアランスＬが大きくなれば、それに連れてモーメントも大きくなる様子がわかる。
例えば、従来の継手５１の取り付けにおいて、クリアランスＬが１．５ｍｍであるとすれば、モーメントＭは約８であり、クリアランスＬが２．０ｍｍであるとすれば、モーメントＭは約１０であることがわかる。
【００１１】
以上のように、作用点Ｓ２には、力Ｆと距離Ｌとを掛けた曲げモーメントが生じる。その結果、この曲げモーメントから発生する応力が矢印Ｃ方向に生じ、継手５１の上部に取り付けられているダイアフラム５３に作用し、ダイアフラム５３を窪ませる方向に変形させ（想像線Ｎ参照）、圧力出力誤差が発生するという問題がある。
【００１２】
そこで、曲げモーメントから発生する応力の影響がダイアフラム５３に及ばないようにするために、つば部５１Ｂの座面５１Ｄからの厚さＴ０を厚くして対応している。その結果、つば部５１Ｂの座面５１Ｄ、言い換えれば、被取付部材５７の取付面表面から継手５１の突出寸法Ｈ０が大きくなる。
また、継手５１の座面５１Ｄの外形寸法φＣ０が、Ｏリング用穴５７Ｂの外径φＡ０より所定寸法大きいことが必要とされることから大きくなる。
そうすると、特に外径の大きなつば部５１Ｂの厚さＴ０が厚くなり、また、外径も大きくなることから、継手５１が大型化し、重量も重くなるという問題が発生する。
【００１３】
本発明の目的は、圧力出力誤差が小さくなり、かつ小型、軽量化が図れる圧力センサを提供することにある。
【００１４】
【課題を解決するための手段】
請求項１に記載の発明は、圧力を検出するダイアフラムと、このダイアフラムに圧力を導入する導入口を有する継手を備えて構成される圧力センサにおいて、前記継手は、被取付部材に取り付けるねじ部と、このねじ部を前記被取付部材にねじ込んで締め付けたとき前記被取付部材に突き当たる座面とを有し、前記継手の前記被取付部材に嵌合する嵌合部の外周で前記座面を含まない位置に、圧力をシールするシール部材が設けられていることを特徴とする圧力センサである。
【００１５】
このような本発明においては、シール部材が座面を含まない位置に設けられているので、座面と嵌合部との交点部に、モーメントを生じるクリアランスを、例えば面取り用の小さなクリアランスとするだけでよくなる。その結果、継手の締め付けトルクで生じる曲げモーメントが小さくなるので、曲げモーメントにより継手に生じる応力を小さくできる。従って、ダイアフラムに与える影響を少なくすることができ、圧力出力誤差を小さくできる。
また、曲げモーメントが小さくなるので、被取付部材の表面からの突出寸法を小さくでき、さらに、シール部材が座面と同一平面内に設けられていないので、座面の径を小さくできる。そのため、圧力センサの小型、軽量化を図ることができる。
【００１６】
請求項２に記載の発明は、請求項１記載の圧力センサにおいて、前記シール部材は、前記ねじ部の端部から離れた位置に設けられていることを特徴とするものである。
このような本発明においては、継手をねじ込む際、ねじ部にシール部材を接触させないで行うことができるので、継手の取り付け時にシール部材を損傷することがない。
【００１７】
請求項３に記載の発明は、請求項１または請求項２記載の圧力センサにおいて、前記被取付部材の前記座面と嵌合部との交点部に対応する部位には、極小寸法の面取り加工が施されていることを特徴とするものである。
このような本発明においては、引っ張り力を生じる点と反力を生じる点との間のクリアランスを極力小さくできる。その結果、継手の締め付けトルクで生じる曲げモーメントを小さくできるので、曲げモーメントにより生じる応力が小さくなり、従って、ダイアフラムに与える影響を少なくすることができ、これにより、圧力出力誤差を小さくできる。
以上の本発明において、極小寸法の面取り加工とは、角部に軽くヤスリ掛けする、いわゆる糸面取りを含み、例えば０．５Ｃ程度までの面取り加工をいう。
【００１８】
請求項４に記載の発明は、請求項１または請求項２記載の圧力センサにおいて、前記継手の座面と前記ねじ部とは連続して形成されるとともに、前記ねじ部の先端には前記嵌合部がねじ部に連続して形成され、この嵌合部の外周に前記シール部材が設けられていることを特徴とするものである。
このような本発明においては、嵌合部がねじ部の先端に設けられているので、嵌合部の先端にねじ部が形成されたものに比べて嵌合部の外径を小さくでき、より小型、軽量化を図ることができ、また、嵌合部にシール部材が設けられているので、シール部材が小さくてすみ、その分安価にできる。
【００１９】
請求項５に記載の発明は、請求項１または請求項２記載の圧力センサにおいて、前記継手の前記ねじ部の先端に前記座面が形成されるとともに、この座面には前記嵌合部が連続して形成され、この嵌合部の外周に前記シール部材が設けられていることを特徴とするものである。
このような本発明においては、座面としては所定の平面部が必要であることから、座面の先端に形成される嵌合部の外径は、ねじ部に直接連続している嵌合部に比べてさらに小さくなり、かつ小型、軽量化を図ることができる。
【００２０】
【発明の実施の形態】
以下に、本発明の圧力センサの実施形態を図面に基づいて説明する。
本実施形態において、前記従来の図５，６で示す圧力センサと異なる部分のみ詳細に説明し、その他の同一部材および同一構造には、同一符号を付すとともに、その詳細な説明は省略または簡略化する。
【００２１】
図１、図２には、第１実施形態の圧力センサ１０が示されている。
この圧力センサ１０では、ねじ部１１Ａとシール部材であるＯリング１８とを異なる位置に設けたものである。
すなわち、圧力センサ１０は継手１１を備えており、この継手１１は、被取付部材１７の雌ねじが切られたねじ部１７Ａにねじ込まれる前記ねじ部１１Ａと、被取付部材１７の嵌合穴１７Ｂに嵌合される嵌合部１１Ｃと、継手１１を被取付部材１７にねじ込んで取り付けるとき、被取付部材１７の取付表面に突き当たる座面１１Ｄを有するつば部１１Ｂとを有して形成されている。
継手１１は、例えばステンレス製となっており、また、つば部１１Ｂは厚さ寸法がＴ１とされ、六角ナット状に形成されている。なお、つば部１１Ｂの厚さ寸法Ｔ１は、前記従来の継手５１のつば部５１Ｂの厚さ寸法Ｔ０より小さな寸法になっている。
【００２２】
前記嵌合部１１Ｃには、図２に詳細を示すように、シール用のＯリング１８が装着されるＯリング用溝１９が、座面１１Ｄから寸法Ｈ２だけ離れた位置に形成されている。また、Ｏリング用溝１９の位置は、ねじ部１１Ａの端部からも所定寸法離れている。
【００２３】
被取付部材１７において、継手１１の座面１１Ｄと嵌合部１１Ｃとの交点に対応する部位は、極小寸法、例えば０．５Ｃで面取りされた面取り部１７Ｃとなっている。また、面取り部１７Ｃの寸法が小さいため、座面１１Ｄの外形寸法φＣ１が、前記従来の継手５１の座面５１Ｄの外形寸法φＣ０よりも小さくなっている。
【００２４】
従って、矢印Ａのように引っ張り方向の力Ｆが働く起点Ｓ１と、矢印Ｂのように反対方向の力Ｆが働く作用点Ｓ２との距離Ｌ１が例えば０．５ｍｍとなっている。また、面取り部１７Ｃがあるため、継手１１のＯリング用溝１９にＯリング１８を装着して継手１１を被取付部材１７に取り付ける際、Ｏリング１８が角部に引っかからず、損傷するおそれが少なくなる。
なお、面取りは０．５Ｃでなくてもよく、軽くヤスリがけする、いわゆる糸面取りでもよい。
【００２５】
以上のような圧力センサ１０を被取付部材１７に取り付けるには、継手１１のＯリング用溝１９にＯリング１８を装着しておいて、継手１１のねじ部１１Ａを被取付部材１７のねじ部１１Ａにねじ込み、Ｏリング１８が被取付部材１７の嵌合穴１７Ｂ位置に到達したら、Ｏリング１８を手で嵌合穴１７Ｂに押し込んでおいて、継手１１のねじ部１１Ａをねじ込む。このねじ込みは、継手５１の座面１１Ｄが被取付部材１７の取付面表面に接触するまで行う。
【００２６】
座面１１Ｄが被取付部材１７の取付面表面に接触したとき、継手１１の座面１１Ｄからの突出寸法はＨ１となっている。そして、この突出寸法（高さ）Ｈ１は、前記従来の継手５１の突出寸法Ｈ０より小さな寸法になっている。
座面１１Ｄが被取付部材１７の表面に接触した後、ねじ部１１Ａが緩まないようにさらに所定のトルクで締め付ける。
【００２７】
このような本実施形態によれば、次のような効果がある。
（１）Ｏリング１８を座面１１Ｄから離れた嵌合部１１Ｃに装着したので、被取付部材１７において、継手１１の座面１１Ｄと嵌合部１１Ｃとの交点に対応する部位には、例えば０．５Ｃで面取り加工した面取り部１７Ｃを形成すればよく、モーメントを発生するクリアランスＬ１を小さくできる。その結果、継手１１の締め付けトルクによる引っ張り力Ｆと、クリアランスＬ１による曲げモーメントから発生する応力が小さくなり、ダイアフラム５３に及ぼす影響を少なくすることができ、圧力出力誤差を小さくできる。
【００２８】
（２）継手１１の、特につば部１１Ｂに生じる曲げモーメントが小さくなるので、継手１１の座面１１Ｄからの高さＨ１を低くでき、また、つば部１１Ｂの厚さＴ１を薄くすることができる。さらに、Ｏリング用溝１９が嵌合部１１Ｃに形成され、座面１１Ｄと同一平面内にないため、座面１１Ｄの外径φＣ１を小さくでき、これにより、継手１１、ひいては圧力センサ１０の小型、軽量化を図ることができる。
【００２９】
（３）嵌合部１１Ｃに形成されたＯリング用溝１９は、座面１１Ｄとねじ部１１Ａとから離れているので、Ｏリング１８を装着して、継手１１をねじ込んで取り付けるとき、継手１１のねじ部１１Ａと被取付部材１７のねじ部１７Ａとの螺合の影響を受けず、継手１１のねじ込みに際してＯリング１８が損傷することはない。
【００３０】
（４）被取付部材１７の、継手１１の座面１１Ｄと嵌合部１１Ｃとの交点に対応する部位には、例えば０．５Ｃで面取りされた面取り部１７Ｃが形成されているので、継手１１のＯリング用溝１９にＯリング１８を装着して継手１１を被取付部材１７に取り付ける際、Ｏリング１８が角部に引っかからず、損傷するおそれが少なくなる。
【００３１】
次に、図３を参照して本発明の圧力センサの第２実施形態を説明する。
本第２実施形態は、前記第１実施形態における継手１１のねじ部１１Ａと嵌合部１１Ｃとの位置を逆にしたものである。
なお、本実施形態において、前記従来の図５，６で示す圧力センサ、および第１実施形態と異なる部分のみ詳細に説明し、その他の同一部材および同一構造には、同一符号を付すとともに、その詳細な説明は省略または簡略化する。
【００３２】
本第２実施形態の圧力センサ２０では、継手２１のつば部２１Ｂに形成された座面２１Ｄにねじ部２１Ａが連続して形成され、このねじ部２１Ａの先端に嵌合部２１Ｃが形成され、この嵌合部２１ＣにＯリング２８を装着するためのＯリング用溝２９が形成されている。なお、ねじ部２１Ａの先端と被取付部材２７における嵌合穴２７Ｂの入り口との間には、所定寸法の隙間が形成されている。
従って、引っ張り方向の力Ｆと反対方向の力Ｆとは同一線上に働くため、曲げモーメントを生じさせるクリアランスが、互いのねじの隙間だけとなってほぼゼロに近くなり、曲げモーメントがほとんど生じなくなる。
【００３３】
このような本実施形態では、継手２１のＯリング用溝２９にＯリング２８を装着してから、継手２１の嵌合部２１Ｃおよびねじ部２１Ａを、被取付部材２７のねじ穴に差し込み、次いで、継手２１のねじ部２１Ａを被取付部材２７のねじ部２７Ａにねじ込んで取り付ける。この際、継手２１の座面２１Ｄが被取付部材２７の取付表面に接触するまでねじ込む。
座面２１Ｄが被取付部材２７の取付表面に接触した後、ねじ部２１Ａが緩まないようにさらに所定のトルクで締め付ける。
【００３４】
このような本実施形態によれば、前記（２）、（３）と同様の効果の他、次のような効果がある。
（５）Ｏリング２８を座面２１Ｄから離れた嵌合部２１Ｃに装着するとともに、座面２１Ｄにねじ部２１Ａを連続させたので、モーメントを発生するクリアランスをほぼゼロにできる。その結果、継手２１の締め付けトルクによる引っ張り力Ｆと、クリアランスによる曲げモーメントから発生する応力がほとんどなくなり、ダイアフラムに与える影響をほとんどなくすことができるため、圧力出力誤差をほとんどなくすことができる。
【００３５】
（６）嵌合部２１Ｃの外径がねじ部２１Ａの外径より小さいので、嵌合部１１Ｃの先端にねじ部１１Ａが形成されている前記第１実施形態に比べて、継手２１を小さくでき、より小型、軽量化を図れる上に、Ｏリング２８が小さいものですみ、その分だけでも第１実施形態より安価にできる。
【００３６】
次に、図４を参照して本発明の圧力センサの第３実施形態を説明する。
本３実施形態は、前記第１、第２実施形態において、それぞれ継手１１，２１のつば部１１Ｂ、２１Ｂに座面１１Ｄ、２１Ｄが形成されていたものを、継手３１のねじ部３１Ａの先端に座面３１Ｄを形成したものである。
【００３７】
すなわち、本第３実施形態の圧力センサ３０では、継手３１のつば部３１Ｂの一面にねじ部３１Ａが連続し、このねじ部３１Ａの先端に前述のように座面３１Ｄが形成され、この座面３１Ｄに連続して嵌合部３１Ｃが形成されている。そして、この嵌合部３１ＣにＯリング３８を装着するためのＯリング用溝３９が形成されている。嵌合部３１Ｃの外径は、前記第２実施形態の嵌合部２１Ｃの外径よりさらに小さくなっており、これにより、ねじ部３１Ａの先端と嵌合部３１Ｃの外径との間の平面部が前記座面３１Ｄとなっている。
【００３８】
これに対して、被取付部材３７のねじ部３７Ａと嵌合部３７Ｂとの間に段差部３７Ｄが形成されており、この段差部３７Ｄが被取付部材３７の取付表面となっている。
この際、継手３１のつば部３１Ｂの一面と被取付部材３７の表面との間には、所定寸法の隙間Ｈ４があけられ、継手３１の突出寸法Ｈ３は、隙間Ｈ４の分だけ前記第２実施形態より高くなっている。
【００３９】
図４において、ねじ先端の座面３１Ｄにおいて、被取付部材３７の矢印Ｄ方向の反力Ｆと、矢印Ｅ方向のねじ先端の押し付け力Ｆが距離Ｌ１を介してかかるため、曲げモーメントが発生するが、座面３１Ｄからの突出寸法Ｈ５は継手３１の突出寸法Ｈ３よりも大きくなり、応力は小さくなる。従って、曲げモーメントが生じてもダイアフラム５３には影響がほとんどなくなる。
【００４０】
このような本実施形態では、継手３１のＯリング用溝３９にＯリング３８を装着してから、被取付部材３７のねじ穴に差し込み、次いで、継手３１のねじ部３１Ａを、継手３１の座面３１Ｄが被取付部材３７の段差部３７Ｄに接触するまで被取付部材３７のねじ部３７Ａにねじ込んで取り付ける。
座面３１Ｄが被取付部材３７の段差部３７Ｄに接触した後、ねじ部３１Ａが緩まないようにさらに所定のトルクで締め付ける。
【００４１】
このような本実施形態によれば、前記（２）、（３）、（５）と同様の効果の他、次のような効果がある。
（７）ねじ部３１Ａの先端に座面３１Ｄが形成され、嵌合部３１Ｃは座面３１Ｄに連続しているので、座面３１Ｄの分だけ嵌合部３１Ｃの径が小さくなり、第２実施形態の嵌合部２１Ｃより小さくでき、さらに小型、軽量化を図ることができる。
【００４２】
なお、本発明は、前記各実施形態に限定されるものではなく、本発明の目的を達成できるものであれば、次に示すような変形形態でもよいものである。
例えば、前記第１実施形態では、被取付部材１７の嵌合穴１７Ｂの縁部に例えば０．５Ｃの面取りがなされているが、これに限らない。極小寸法のＲ加工でもよい。このようにすれば、Ｏリング１８を装着して継手１１を取り付けるとき、Ｒ部を経由して被取付部材１７の嵌合穴１７Ｂに挿入されるので、Ｏリング１８がより傷つきにくい。
【００４３】
【発明の効果】
以上に説明したように、本発明の圧力センサによれば、シール部材が座面を含まない位置に設けられているので、座面と嵌合部との交点部に、モーメントを生じるクリアランスを、例えば面取り用の小さなクリアランスとするだけでよくなる。その結果、継手の締め付けトルクで生じる曲げモーメントが小さくなるので、曲げモーメントにより継手に生じる応力を小さくできる。従って、ダイアフラムに与える影響を少なくすることができ、圧力出力誤差を小さくできる。
また、曲げモーメントが小さくなるので、被取付部材の表面からの突出寸法を小さくでき、さらに、シール部材が座面と同一平面内に設けられていないので、座面の径を小さくできる。そのため、圧力センサの小型、軽量化を図ることができる。
【図面の簡単な説明】
【図１】本発明に係る圧力センサの第１実施形態を示す全体図である。
【図２】前記実施形態の部分詳細図である。
【図３】本発明に係る圧力センサの第２実施形態を示す全体図である。
【図４】本発明に係る圧力センサの第３実施形態を示す全体図である。
【図５】従来の圧力センサを示す全体図である。
【図６】従来の圧力センサを示す部分詳細図である。
【図７】従来の圧力センサにおける締め付けによるモーメントとクリアランスとの関係を示す図である。
【符号の説明】
１０，２０，３０圧力センサ
１１，２１，３１継手
１１Ａ，２１Ａ，３１Ａねじ部
１１Ｃ，２１Ｃ，３１Ｃ嵌合部
１１Ｄ，２１Ｄ，３１Ｄ座面
１７，２７，３７被取付部材
１８，２８，３８シール部材であるＯリング
１９，２９，３９Ｏリング用溝[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pressure sensor for detecting air pressure or oil pressure used in, for example, an FA (Factory Automation) device.
[0002]
[Background Art]
2. Description of the Related Art Conventionally, there has been known a pressure sensor which is attached to various devices such as an FA device and detects air pressure and hydraulic pressure used in those devices.
The mounting of the pressure sensor is often performed by screwing it into a counterpart such as a device (for example, Patent Document 1).
[0003]
The mounting structure of this pressure sensor is as shown in FIGS.
That is, the pressure sensor 50 includes a joint 51. The joint 51 has a screw portion 51A and a flange portion 51B having a larger outer shape than the screw portion 51A. The outer shape of the collar portion 51B is formed in a hexagonal nut shape. Have been. A diaphragm 53 is attached to an upper part of the joint 51, and a case member 52 is provided at one end of the joint 51 on the flange 51 B side. A circuit board 54, a feedthrough capacitor 55, and the like are provided inside the case member 52, and the diaphragm 53 is also covered with the case member 52.
[0004]
In the flange portion 51B of the joint 51, a seat surface 51D is formed, which abuts against the mounting surface of the mounted member 57 when the screw portion 51A of the joint 51 is screwed into the screw portion 57A of the mounted member 57 such as a device. . An O-ring 58, which is a seal member, is attached to the lower part of the neck of the collar portion 51B, that is, to the intersection between the bearing surface 51D and the screw portion 57A.
[0005]
The O-ring 58 is formed in an O-ring groove 59 formed by an O-ring hole 57B formed on the periphery of the screw portion 57A of the attached member 57 and a groove 51C formed by recessing from the screw portion 51A of the joint 51. It is to be housed in.
Here, when the outer diameter of the O-ring hole 57B is φA0, the inner diameter of the groove 51C is φB0, and the outer diameter of the seating surface 51D is φC0, the relationship is φB0 <φA0 <φC0.
[0006]
In order to mount such a joint 51, an O-ring 58 is mounted in the O-ring groove 59, and the screw portion 51A of the joint 51 is screwed into the screw portion 57A of the member 57 to be mounted. At this time, the height (thickness) of the flange portion 51B of the joint 51 is T0, and the protrusion dimension of the joint 51 from the bearing surface 51D is H0.
Note that a pressure introduction port 51 E is provided in the axis of the joint 51.
[0007]
[Patent Document 1]
JP-A-10-153509 (conventional example; see FIG. 10)
[0008]
[Problems to be solved by the invention]
By the way, when the joint 51 is screwed into the member to be mounted 57 and attached, a force F that pulls in the direction of arrow A is generated at the periphery of the groove 51C for the O-ring 58, that is, at the starting point S1 of the moment. . On the other hand, a reaction force in the direction of the arrow B acting in the opposite direction to the arrow A is applied to a portion of the collar portion 51B which abuts against the inner periphery of the O-ring hole 57B of the attached member 57, that is, the point of action S2 of the moment. F occurs. Therefore, a moment (M) corresponding to the distance between the starting point S1 and the acting point S2 is generated at the acting point S2.
The moment (M) due to the tightening of the screw is calculated based on Equation 1.
Here, a is the distance from the axis center of the joint 51 to the action point S2 where the stress is generated, b is the distance from the axis center of the joint 51 to the starting point S1, and L is the difference (clearance) between a and b. I do.
[0009]
(Equation 1)

[0010]
FIG. 7 shows the result of calculation based on Equation 1.
As shown in FIG. 7, it can be seen that the moment M changes according to the dimension of the clearance L in a curve that is slightly closer to a proportional state, and that as the clearance L increases, the moment increases accordingly.
For example, when the conventional joint 51 is attached, the moment M is about 8 if the clearance L is 1.5 mm, and the moment M is about 10 if the clearance L is 2.0 mm. I understand.
[0011]
As described above, a bending moment multiplied by the force F and the distance L is generated at the point of action S2. As a result, the stress generated from this bending moment is generated in the direction of arrow C, acts on the diaphragm 53 attached to the upper part of the joint 51, and deforms the diaphragm 53 in a direction to depress (see the imaginary line N), and outputs the pressure. There is a problem that an error occurs.
[0012]
In order to prevent the influence of the stress generated from the bending moment from affecting the diaphragm 53, the thickness T0 of the flange portion 51B from the bearing surface 51D is increased. As a result, the protrusion dimension H0 of the joint 51 from the seating surface 51D of the collar portion 51B, in other words, the mounting surface of the mounted member 57 increases.
In addition, the outer dimension φC0 of the seating surface 51D of the joint 51 is required to be larger than the outer diameter φA0 of the O-ring hole 57B by a predetermined dimension, which is larger.
Then, in particular, the thickness T0 of the flange portion 51B having a large outer diameter increases, and the outer diameter also increases, which causes a problem that the joint 51 becomes larger and heavier.
[0013]
An object of the present invention is to provide a pressure sensor which can reduce a pressure output error and can be reduced in size and weight.
[0014]
[Means for Solving the Problems]
The invention according to claim 1 is a pressure sensor configured to include a diaphragm for detecting pressure and a joint having an inlet for introducing pressure to the diaphragm, wherein the joint includes a screw portion attached to a member to be mounted. A seat surface that abuts the mounted member when the screw portion is screwed into the mounted member and tightened, and includes the seat surface at an outer periphery of a fitting portion of the joint that fits the mounted member. The pressure sensor is characterized in that a seal member for sealing pressure is provided at a position where there is no pressure.
[0015]
In the present invention, since the seal member is provided at a position that does not include the seating surface, the clearance that generates a moment at the intersection of the seating surface and the fitting portion is, for example, a small clearance for chamfering. Just get better. As a result, the bending moment generated by the tightening torque of the joint is reduced, so that the stress generated in the joint due to the bending moment can be reduced. Therefore, the influence on the diaphragm can be reduced, and the pressure output error can be reduced.
Further, since the bending moment is reduced, the protrusion dimension from the surface of the member to be mounted can be reduced, and the diameter of the seat surface can be reduced since the seal member is not provided on the same plane as the seat surface. Therefore, the size and weight of the pressure sensor can be reduced.
[0016]
According to a second aspect of the present invention, in the pressure sensor according to the first aspect, the seal member is provided at a position distant from an end of the screw portion.
In such a present invention, when the joint is screwed in, the sealing can be performed without bringing the seal member into contact with the threaded portion, so that the seal member is not damaged when the joint is attached.
[0017]
According to a third aspect of the present invention, in the pressure sensor according to the first or second aspect, a portion corresponding to an intersection between the seating surface and the fitting portion of the attached member is chamfered to a minimum dimension. Is provided.
In the present invention as described above, the clearance between the point where the pulling force is generated and the point where the reaction force is generated can be minimized. As a result, the bending moment generated by the tightening torque of the joint can be reduced, so that the stress generated by the bending moment is reduced, and therefore, the influence on the diaphragm can be reduced, thereby reducing the pressure output error.
In the present invention described above, the chamfering process of the extremely small size includes a so-called yarn chamfering in which a corner portion is lightly filed, and refers to a chamfering process up to, for example, about 0.5C.
[0018]
According to a fourth aspect of the present invention, in the pressure sensor according to the first or second aspect, the seating surface of the joint and the screw portion are formed continuously, and the fitting is formed at a tip of the screw portion. The joint portion is formed continuously with the screw portion, and the seal member is provided on the outer periphery of the fitting portion.
In the present invention, since the fitting portion is provided at the tip of the screw portion, the outer diameter of the fitting portion can be made smaller than that in which the thread portion is formed at the tip of the fitting portion. The size and weight can be reduced, and the seal member is provided at the fitting portion, so that the seal member can be small and the cost can be reduced accordingly.
[0019]
According to a fifth aspect of the present invention, in the pressure sensor according to the first or second aspect, the seat surface is formed at a tip of the screw portion of the joint, and the fitting portion is formed on the seat surface. It is formed continuously, and the seal member is provided on the outer periphery of the fitting portion.
In the present invention, since a predetermined flat portion is required as the seating surface, the outer diameter of the fitting portion formed at the tip of the seating surface is equal to the fitting portion directly connected to the screw portion. , And can be made smaller and lighter.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a pressure sensor of the present invention will be described with reference to the drawings.
In the present embodiment, only the portions different from the conventional pressure sensor shown in FIGS. 5 and 6 will be described in detail, and the other same members and structures will be denoted by the same reference numerals, and detailed description thereof will be omitted or simplified. I do.
[0021]
1 and 2 show a pressure sensor 10 according to a first embodiment.
In this pressure sensor 10, a screw portion 11A and an O-ring 18 as a seal member are provided at different positions.
That is, the pressure sensor 10 includes a joint 11. The joint 11 is inserted into the threaded portion 11 A of the attached member 17, which is screwed into the internally threaded threaded portion 17 A, and the fitting hole 17 B of the attached member 17. It is formed to have a fitting portion 11C to be fitted, and a flange portion 11B having a seat surface 11D that abuts against a mounting surface of the mounted member 17 when the joint 11 is screwed into the mounted member 17.
The joint 11 is made of, for example, stainless steel, and the flange portion 11B has a thickness T1 and is formed in a hexagonal nut shape. The thickness T1 of the collar 11B is smaller than the thickness T0 of the collar 51B of the conventional joint 51.
[0022]
As shown in detail in FIG. 2, an O-ring groove 19 in which a sealing O-ring 18 is mounted is formed in the fitting portion 11C at a position away from the seat surface 11D by a dimension H2. The position of the O-ring groove 19 is also apart from the end of the threaded portion 11A by a predetermined distance.
[0023]
In the mounted member 17, a portion corresponding to the intersection between the seat surface 11D of the joint 11 and the fitting portion 11C is a chamfered portion 17C chamfered with a minimum dimension, for example, 0.5C. Further, since the size of the chamfered portion 17C is small, the outer dimension φC1 of the seat surface 11D is smaller than the outer dimension φC0 of the seat surface 51D of the conventional joint 51.
[0024]
Therefore, the distance L1 between the starting point S1 where the force F in the pulling direction acts as shown by the arrow A and the point S2 where the force F acts in the opposite direction as shown by the arrow B is 0.5 mm, for example. In addition, since the chamfered portion 17C is provided, when the O-ring 18 is mounted on the O-ring groove 19 of the joint 11 and the joint 11 is mounted on the member 17 to be mounted, the O-ring 18 may not be caught at the corner and may be damaged. Less.
Note that the chamfering need not be 0.5C, but may be so-called thread chamfering, which is lightly filed.
[0025]
In order to attach the pressure sensor 10 to the member 17 to be attached, the O-ring 18 is attached to the groove 19 for the O-ring of the joint 11, and the thread 11 A of the joint 11 is When the O-ring 18 reaches the position of the fitting hole 17B of the member 17 to be mounted, the O-ring 18 is manually pushed into the fitting hole 17B, and the screw portion 11A of the joint 11 is screwed. This screwing is performed until the seat surface 11D of the joint 51 comes into contact with the mounting surface of the member 17 to be mounted.
[0026]
When the seat surface 11D contacts the surface of the mounting surface of the member 17 to be mounted, the protrusion of the joint 11 from the seat surface 11D is H1. The projection dimension (height) H1 is smaller than the projection dimension H0 of the conventional joint 51.
After the seat surface 11D contacts the surface of the member 17 to be mounted, the screw portion 11A is further tightened with a predetermined torque so as not to be loosened.
[0027]
According to this embodiment, the following effects can be obtained.
(1) Since the O-ring 18 is mounted on the fitting portion 11C remote from the seating surface 11D, a portion of the attached member 17 corresponding to the intersection between the seating surface 11D of the joint 11 and the fitting portion 11C includes, for example, The chamfered portion 17C formed by chamfering at 0.5C may be formed, and the clearance L1 for generating a moment can be reduced. As a result, the tensile force F due to the tightening torque of the joint 11 and the stress generated from the bending moment due to the clearance L1 are reduced, and the influence on the diaphragm 53 can be reduced, and the pressure output error can be reduced.
[0028]
(2) Since the bending moment of the joint 11, especially at the flange 11 B, is reduced, the height H 1 of the joint 11 from the bearing surface 11 D can be reduced, and the thickness T 1 of the collar 11 B can be reduced. . Further, since the O-ring groove 19 is formed in the fitting portion 11C and is not in the same plane as the seating surface 11D, the outer diameter φC1 of the seating surface 11D can be reduced, thereby reducing the size of the joint 11, and hence the pressure sensor 10. Thus, the weight can be reduced.
[0029]
(3) Since the O-ring groove 19 formed in the fitting portion 11C is separated from the bearing surface 11D and the screw portion 11A, when the O-ring 18 is mounted and the joint 11 is screwed in and mounted, the joint 11 And the O-ring 18 is not damaged when the joint 11 is screwed.
[0030]
(4) Since a chamfered portion 17C which is chamfered at 0.5C, for example, is formed at a portion of the attached member 17 corresponding to an intersection between the seat surface 11D of the joint 11 and the fitting portion 11C, the joint 11 When the O-ring 18 is mounted in the O-ring groove 19 and the joint 11 is mounted on the member 17 to be mounted, the O-ring 18 does not catch on the corners and the risk of damage is reduced.
[0031]
Next, a second embodiment of the pressure sensor of the present invention will be described with reference to FIG.
In the second embodiment, the positions of the threaded portion 11A and the fitting portion 11C of the joint 11 in the first embodiment are reversed.
In the present embodiment, only the portions different from the conventional pressure sensor shown in FIGS. 5 and 6 and the first embodiment will be described in detail, and the other same members and the same structures will be denoted by the same reference numerals, and Detailed description is omitted or simplified.
[0032]
In the pressure sensor 20 of the second embodiment, a screw portion 21A is continuously formed on a seat surface 21D formed on a flange portion 21B of the joint 21, and a fitting portion 21C is formed at a tip of the screw portion 21A. An O-ring groove 29 for mounting the O-ring 28 is formed in the fitting portion 21C. It should be noted that a gap of a predetermined size is formed between the tip of the screw portion 21A and the entrance of the fitting hole 27B in the attached member 27.
Therefore, since the force F in the pulling direction and the force F in the opposite direction act on the same line, the clearance for generating the bending moment becomes almost zero due to only the gap between the screws, and almost no bending moment is generated. .
[0033]
In this embodiment, after the O-ring 28 is attached to the O-ring groove 29 of the joint 21, the fitting portion 21 C and the screw portion 21 A of the joint 21 are inserted into the screw holes of the attached member 27, and then Then, the screw portion 21A of the joint 21 is screwed into the screw portion 27A of the mounted member 27 and attached. At this time, the screw is screwed until the seat surface 21D of the joint 21 contacts the mounting surface of the member 27 to be mounted.
After the seat surface 21D contacts the mounting surface of the mounted member 27, the screw portion 21A is further tightened with a predetermined torque so as not to be loosened.
[0034]
According to the present embodiment, the following effects are obtained in addition to the effects similar to the above (2) and (3).
(5) Since the O-ring 28 is mounted on the fitting portion 21C remote from the seating surface 21D and the screw portion 21A is continuous with the seating surface 21D, the clearance for generating a moment can be reduced to almost zero. As a result, the stress generated by the tensile force F due to the tightening torque of the joint 21 and the bending moment due to the clearance is almost eliminated, and the influence on the diaphragm can be almost eliminated, so that the pressure output error can be almost eliminated.
[0035]
(6) Since the outer diameter of the fitting portion 21C is smaller than the outer diameter of the screw portion 21A, the joint 21 can be made smaller than in the first embodiment in which the screw portion 11A is formed at the tip of the fitting portion 11C. In addition, the O-ring 28 can be smaller and lighter, and the O-ring 28 can be smaller, and the O-ring 28 alone can be less expensive than the first embodiment.
[0036]
Next, a third embodiment of the pressure sensor of the present invention will be described with reference to FIG.
The third embodiment is different from the first and second embodiments in that the

flanges

11B and 21B of the

joints

11 and 21 are formed with the bearing surfaces 11D and 21D, respectively. The seat surface 31D is formed.
[0037]
That is, in the pressure sensor 30 of the third embodiment, the screw portion 31A is continuous with one surface of the flange portion 31B of the joint 31, and the seat surface 31D is formed at the tip of the screw portion 31A as described above. A fitting portion 31C is formed continuously from 31D. An O-ring groove 39 for mounting the O-ring 38 on the fitting portion 31C is formed. The outer diameter of the fitting portion 31C is smaller than the outer diameter of the fitting portion 21C of the second embodiment, and as a result, a plane between the tip of the screw portion 31A and the outer diameter of the fitting portion 31C is formed. The portion is the seat surface 31D.
[0038]
On the other hand, a step 37D is formed between the screw portion 37A and the fitting portion 37B of the mounted member 37, and the step 37D is a mounting surface of the mounted member 37.
At this time, a gap H4 having a predetermined dimension is provided between one surface of the flange portion 31B of the joint 31 and the surface of the attached member 37, and the protrusion dimension H3 of the joint 31 is equal to the gap H4 in the second embodiment. It is higher than the form.
[0039]
In FIG. 4, a reaction force F of the mounting member 37 in the direction of arrow D and a pressing force F of the screw tip in the direction of arrow E are applied on the bearing surface 31D of the screw tip via the distance L1, and a bending moment is generated. However, the protrusion dimension H5 from the bearing surface 31D is larger than the protrusion dimension H3 of the joint 31, and the stress is reduced. Therefore, even if a bending moment occurs, the diaphragm 53 is hardly affected.
[0040]
In this embodiment, after the O-ring 38 is mounted in the O-ring groove 39 of the joint 31, the O-ring 38 is inserted into the screw hole of the attached member 37, and then the threaded portion 31 A of the joint 31 is seated on the joint 31. It is screwed into the threaded portion 37A of the attached member 37 until the surface 31D comes into contact with the step portion 37D of the attached member 37.
After the seat surface 31D comes into contact with the step portion 37D of the attached member 37, the screw portion 31A is further tightened with a predetermined torque so as not to be loosened.
[0041]
According to the present embodiment, the following effects are obtained in addition to the effects similar to the above (2), (3), and (5).
(7) Since the seating surface 31D is formed at the tip of the screw portion 31A and the fitting portion 31C is continuous with the seating surface 31D, the diameter of the fitting portion 31C is reduced by the amount of the seating surface 31D. It can be smaller than the fitting portion 21C in the form, and can be further reduced in size and weight.
[0042]
The present invention is not limited to the above embodiments, but may be modified as follows as long as the object of the present invention can be achieved.
For example, in the first embodiment, the edge of the fitting hole 17B of the attached member 17 is chamfered by, for example, 0.5C, but is not limited thereto. Extremely small radius processing may be used. With this configuration, when the O-ring 18 is mounted and the joint 11 is mounted, the O-ring 18 is inserted into the fitting hole 17B of the mounted member 17 via the R portion, so that the O-ring 18 is less likely to be damaged.
[0043]
【The invention's effect】
As described above, according to the pressure sensor of the present invention, since the seal member is provided at a position that does not include the seating surface, a clearance that generates a moment at the intersection of the seating surface and the fitting portion is For example, a small clearance for chamfering is sufficient. As a result, the bending moment generated by the tightening torque of the joint is reduced, so that the stress generated in the joint by the bending moment can be reduced. Therefore, the influence on the diaphragm can be reduced, and the pressure output error can be reduced.
Further, since the bending moment is reduced, the protrusion dimension from the surface of the mounted member can be reduced, and further, since the seal member is not provided on the same plane as the seat surface, the diameter of the seat surface can be reduced. Therefore, the size and weight of the pressure sensor can be reduced.
[Brief description of the drawings]
FIG. 1 is an overall view showing a first embodiment of a pressure sensor according to the present invention.
FIG. 2 is a partial detailed view of the embodiment.
FIG. 3 is an overall view showing a second embodiment of the pressure sensor according to the present invention.
FIG. 4 is an overall view showing a third embodiment of the pressure sensor according to the present invention.
FIG. 5 is an overall view showing a conventional pressure sensor.
FIG. 6 is a partial detailed view showing a conventional pressure sensor.
FIG. 7 is a diagram showing a relationship between a moment by tightening and a clearance in a conventional pressure sensor.
[Explanation of symbols]
10, 20, 30

Pressure sensors

11, 21, 31

Joints

11A, 21A, 31A Screws 11C, 21C, 31C Fittings 11D, 21D, 31D Seats 17, 27, 37 Attached

members

18, 28, 38 Seal members O-

rings

19, 29, and 39 O-ring grooves

Claims

In a pressure sensor comprising a diaphragm for detecting pressure and a joint having an inlet for introducing pressure to the diaphragm,
The joint has a screw portion to be attached to the attached member, and a seat surface which abuts the attached member when the screw portion is screwed into the attached member and tightened,
A pressure sensor, wherein a seal member that seals pressure is provided at a position on the outer periphery of a fitting portion of the joint that fits the member to be mounted and that does not include the seating surface.

The pressure sensor according to claim 1,
The pressure sensor, wherein the seal member is provided at a position apart from an end of the screw portion.

The pressure sensor according to claim 1 or 2,
A pressure sensor, wherein a portion corresponding to an intersection of the seat surface and the fitting portion of the mounted member is chamfered to an extremely small size.

The pressure sensor according to claim 1 or 2,
The seat surface of the joint and the screw portion are formed continuously, and the fitting portion is formed at the tip of the screw portion so as to be continuous with the screw portion. The pressure sensor characterized by being provided with.

The pressure sensor according to claim 1 or 2,
The seat surface is formed at the tip of the thread portion of the joint, the fitting portion is formed continuously on the seat surface, and the seal member is provided on the outer periphery of the fitting portion. Pressure sensor characterized by the above-mentioned.