JP3689987B2

JP3689987B2 - Ultrasonic flow meter

Info

Publication number: JP3689987B2
Application number: JP19191896A
Authority: JP
Inventors: 茂岩永; 行夫長岡
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1996-07-22
Filing date: 1996-07-22
Publication date: 2005-08-31
Anticipated expiration: 2016-07-22
Also published as: JPH1038649A

Description

【０００１】
【発明の属する技術分野】
本発明は、流量の計測を行う超音波式流量計に関するものである。
【０００２】
【従来の技術】
従来のこの種の計測装置として、図１１に示すように、流れに直交する方向の断面が矩形の流体流路１の一部に超音波振動子２と３を対向するように配置し、超音波振動子２から発した超音波を超音波振動子３で検出するまでの時間を計測し、この時間から流体の速度を演算して流量を算出する流量計があった。
【０００３】
【発明が解決しようとする課題】
しかしながら、従来の流量計では、矩形の断面形状により流路での流体の流速分布をできるだけ二次元的に形成して測定精度の向上を図っていたが、アスペクト比（長辺長さＨ０／短辺長さＷ０）を大きくして偏平化し、且つ流路長さを大きくするには加工上の制約があり、さらにこのアスペクト比の大きな矩形流路による高測定精度化と被測定流体の流動を制御する制御弁を組込んだ流量計のコンパクト化を両立できないという課題を有していた。
【０００４】
【課題を解決するための手段】
本発明は上記課題を解決するために、矩形断面を有する測定路の上流側および下流側に導入路と導出路を設けてＵ字体とし、このＵ字体の導入路の外側に開閉体を収納する流量制御室を設け、測定路の上流側および下流側に対向して超音波振動子を配置したものである。
【０００５】
上記発明によれば、測定路の断面アスペクト比および流路長さをそれぞれ大きく設定した上でコンパクトに構成できるため、測定精度が高く小型コンパクトな流量計を低コストで実現できる。
【０００６】
【発明の実施の形態】
本発明は、矩形断面を有する測定路と、前記測定路の上流側に設けた導入路と、前記測定路の下流側に設けた導出路と、前記導入路に流入する被測定流体を制御する開閉体と、前記導入路に連通され前記開閉体を設けた流量制御室と、前記流量制御室の上流側に設けた入口部と、前記導出路の下流側に設けた出口部と、前記測定路の上流側および下流側に対向して設けた超音波振動子と、前記超音波振動子からの信号を基に流量を算出する流量演算部とを備え、前記導入路、前記測定路、前記導出路をＵ字状に形成したＵ字体を有するものである。そして、測定部での被測定流体は、上流側および下流側に設けた導入路と導出路により流れが安定化されるとともに矩形断面の大きなアスペクト比により流れ状態の二次元性が高められ、さらに超音波振動子が測定部の上流側および下流側に設けられて超音波が測定路を伝播する距離を長く設定できるので流れによる超音波の伝達時間変化が大きくなり、流れ状態の改善および超音波の伝播時間の解析精度の両面で測定精度を向上できる。また、導入路、測定路、導出路をＵ字状に形成したＵ字体の外側から開閉体を収める流量制御室を設けるとともに超音波振動子を測定路の上流側および下流側に設けることで、上流側の超音波振動子と開閉体の配置の干渉をなくして測定路の流れ方向側（図１の左右方向）の長さとＵ字状の奥行き方向（図１の紙面方向）の長さをそれぞれ短縮して流量計の小型化を実現できる。また、流量制御室の開閉体を取付ける穴および導入路に連通する穴は外側から容易に加工可能のため低コスト化ができる。
【０００７】
また、対向する超音波振動子は測定路の被測定流体の流れを横切るように流れ方向に対して所定の角度を設けて配置したものである。そして、超音波振動子から出される超音波は、測定路を貫流する被測定流体に対して流れに直交する断面すなわち矩形断面の長辺方向にわたって流速の測定を行うため、アスペクト比を大きくした矩形断面により二次元性を高められた流れ状態に対してさらに矩形断面の長辺方向に平均化して流速を計るため、より高精度の流量測定ができる。また、上流側の超音波振動子と開閉体の配置上の干渉がより一層避け易くなるため、流量計のより一層の小型化ができる。
【０００８】
また、入口部、流量制御室、導入路、測定路、導出路、出口部を一体成形したものである。そして、上記各部の一体成形により部品点数の削減と加工および組立時間の低減により低コスト化が実現できる。また、一体成形により被測定流体の流路が高強度に構成され流量測定部の形状安定性が確保できるため、流量計の耐久性および信頼性を向上できる。
【０００９】
また、入口部、出口部を機械的に固定する接続体と、この接続体とＵ字体との間で形成した空間部と、この空間部に流量演算部を収納したものである。そして、外部との接続口である入口部および出口部を接続体で固定しているので流量計の高強度化により信頼性が向上できる。また、接続体とＵ字体との間で形成した空間部に流量演算部を収納することで流量計をより小型化できる。また流量演算部は接続体とＵ字体により必然的に４面を金属材料で囲うことができ、残りの２面を囲うだけで流量演算部はその全面を外部からの電波などの外乱から遮蔽でき、低コストで信頼性を向上することができる。
【００１０】
また、無線送受信手段と、この無線送受信手段とＵ字体を覆う電波透過性材料で構成した筐体を備えたものである。そして、Ｕ字体により流量計の強度が確保できるため、筐体は強度部材と考えなくて良く合成樹脂などの電波透過性材料にして無線送受信手段を筐体の外部に別設することなく内蔵でき、流量計の小型化と低コスト化ができる。
【００１１】
また、超音波振動子の少なくとも上流側には被測定流体中の水分を凝縮液化させる凝縮促進部を設けたものである。そして、被測定流体中の水分は凝縮促進部で凝縮液化されて低減されるため超音波振動子への水分の結露付着が防止され、超音波振動子への水分の付着による超音波の受送信機能の劣化を防止して測定機能の確保および測定精度の確保に対する信頼性を高めることができる。
【００１２】
また、凝縮促進部は、接続体の外表面にフィンを設けて構成したものである。そして、流量計の外部に接する外表面積が広い接続体にさらに表面積を拡大するフィンを設けるため、このフィンに熱的に対向する流量計内の流路が外気温度により十分冷やされて被測定流体内の湿度が高い場合は水分の凝縮が確実にでき、信頼性をより一層向上できる。また、接続体の外表面積が広いためフィンを設置する位置は加工し易い場所に任意に設定でき加工性を向上できる。さらにフィンを接続体の補強部として併用できるため、流量計の耐久性を向上できる。
【００１３】
また、少なくとも測定路には断熱材を設けたものである。そして、断熱材により測定路が外気温度により他の部分より速く冷却されるのを防止して超音波振動子への結露をなくし、流量測定の信頼性をより一層向上できる。
【００１４】
以下、本発明の実施例について図面を参照して説明する。
【００１５】
（実施例１）
図１は本発明の実施例１の超音波式流量計の縦断面図、図２は図１のＡ−Ａ線断面図である。図１、図２において、４は被測定流体の流れ方向に対して直交する断面が長辺を流路幅Ｗ、短辺を流路高さＨの矩形形状とした測定路であり、５は測定路４の上流側でかつ矩形断面の流路高さＨの方向に設けた導入路であり、６は測定路４の下流側でかつ導入路５と同じ側に設けた導出路であり、導入路５および導出路６はそれぞれ測定路４の断面形状に近い寸法形状である。７は導入路５に開閉制御口８を介して連通され導出路６と反対側に位置するように配置した流量制御室である。９は流量制御室７に設けた開閉体であり、開閉制御口８を開閉する弁部９ａと弁部９ａを駆動する駆動部９ｂを有し、被測定流体が導入路５へ流入する量を制御するものである。１０は流量制御室７の上流側に設け流量制御室７に連通する入口部であり、その外周部にはねじ等の連結手段１０ａが設けられている。１１は導出路６の下流側に設けた出口部であり、その外周部にはねじ等の連結手段１１ａが設けられている。１２は導入路５、測定路４、導出路６をＵ字状に形成したＵ字体であり、測定路４を上方に配置し下方に導入路５および導出路６を延ばした逆Ｕ字の形をしている。１３は測定路４の上流側および下流側に対向して設けた超音波振動子であり、１４は超音波振動子１３からの信号を基に流量を算出する流量演算部である。流量演算部１４は超音波振動子１３に対する信号発生・処理部１５ａ、演算部１５ｂおよび開閉体９を動作させる開閉制御部１６を備えている。
【００１６】
次に動作を説明する。まず、流量計の利用開始にあたり開閉制御部１６により開閉体９の駆動部９ｂを駆動して弁部９ａを開閉制御口８から開放（図１の状態）する。被測定流体は入口部１０より流入し流量制御室７に入り、開閉制御口８を経て導入路５へ流入する。測定路４の断面に近い形状・寸法に設定された導入路５に流入した流れはその流れ状態を安定させて測定路４に流入する。測定路４では流路幅Ｗに対して流路高さＨを十分小さく設定したアスペクト比の大きな断面形状により、流路断面での流れ状態の二次元性が確保される。測定路４を出た流れは導出路６を経て出口部１１より流出する。導出路６は測定路４の断面に近い形状・寸法に設定されているため、測定路４の下流端での流れは上記二次元性が確保される。すなわち測定路４の流れ方向の全域にわたって流れ状態の二次元性が確保される。
【００１７】
次に、測定路４での流量の測定は信号発生・処理部１５ａの作用により対向配置された一対の超音波振動子１３間で超音波の送受が行なわれる。このとき流量演算部１４では、一対の超音波振動子１３間で計測される信号を信号発生・処理部１５ａで処理し、さらに演算部１５ｂにおいて被測定流体の流速に応じた超音波の伝播時間より流速が計算される。この流速と測定路４の断面積に基づいて流量が算出される。この流量計測値に基づき被測定流体の流量が過大など異常と見なすことができる場合などでは、開閉制御部１６により開閉体９を駆動して弁部９ｂを開閉制御口８に当接させて被測定流体の流れを停止（図示せず）させる。
【００１８】
このように、一対の超音波振動子１３間の流れをよぎる距離を測定路４に対して最大限に長く設定できるため、超音波の伝播時間の変化を確実に検出でき、高精度の測定ができる。また、被測定流体は測定路４の全域で流れ状態の二次元性が高められ、さらに一対の超音波振動子１３が測定路４の上流側および下流側に設けられて超音波が測定路４を伝播する距離を長く設定できるので、流れ状態の改善および超音波の伝播の両面で測定精度を向上できる。また、導入路５、測定路４、導出路６をＵ字状に形成したＵ字体１２の外側から開閉体９を収める流量制御室７を設けるとともに一対の超音波振動子１３を測定路４の上流側および下流側に設けることで、上流側の超音波振動子１３と開閉体９の配置の干渉をなくして測定路４の流れ方向側の長さＬとＵ字状の奥行き方向（図１の紙面方向）の長さをそれぞれ短縮して流量計の小型化を実現できる。また、流量制御室７の開閉体９を取付ける穴および導入路５に連通する開閉制御口８は外側から容易に加工可能のため低コスト化ができる。
【００１９】
（実施例２）
図３は本発明の実施例２の超音波式流量計の測定路４を示し、図１のＢ−Ｂ線で切断した場合に相当する断面図である。図３において、一対の超音波振動子１３は測定路４の上流側および下流側に互いに対向するように設けたもので、測定路４の被測定流体の流れ方向全域にわたり測定可能とするとともに流路幅Ｗの方向に被測定流体の流れを横切るように流れ方向（矢印Ｃ）に対して所定の角度θを設けて配置されている。
【００２０】
従って、一方の超音波振動子１３から発信された超音波は、測定路４を貫流する被測定流体に対して流れに直交する断面すなわち矩形断面の長辺方向である流路幅Ｗにわたって流れを横切って他方の超音波振動子１３で受信される。ここで測定路４での流れ状態はアスペクト比を大きくした矩形断面により二次元性を高められることと、さらに矩形断面の長辺方向である流路幅Ｗにわたり平均の流速を計ることのため、より一層の高精度の流量測定ができる。また、上流側の超音波振動子１３と開閉体９は偏心して配置されるため、配置上の干渉がより一層避け易くなり、流量計の外形寸法に影響する高さ寸法Ｙ（図１に示す）を小さくして流量計の小型化ができる。また、一対の超音波振動子１３を測定路４の上流側および下流側の端面に配置することにより、一対の超音波振動子１３は流路幅Ｗの方向への飛び出し量が低減でき、流量計の外形寸法に影響する奥行き寸法Ｄを小さくできる。従って、流量計のより一層の小型化ができる。
【００２１】
（実施例３）
図４は本発明の実施例３の超音波式流量計の流路体の分解斜視図である。図４において、１７は入口部１０と、流量制御室７、導入路５、測定路４、導出路６からなるＵ字体１２と、出口部１１とを金属材料で一体成形した流路体である。１８は流路体１７の流量制御室７の一面に設けた第一開口部、１９はＵ字体１２の一面に設けた第二開口部であり、第一開口部１８および第二開口部１９は同一面側に設けられている。２０は第一開口部１８および第二開口部１９を封止する封止体であり、封止体２０はパッキン材（図示せず）あるいはシール剤（図示せず）を介して流路体１７に取付けられる。
【００２２】
このように、一体成形により被測定流体の流路である流路体１７が高強度に構成されるため、測定部の歪みあるいは外力による変形などを防止して測定部の形状安定性が確保でき、流量計の耐久性および信頼性を向上できる。
【００２３】
また、各部の一体成形により部品点数が削減でき、加工時間および組立時間などの低減により低コスト化が実現できる。
【００２４】
（実施例４）
図５は本発明の実施例４の超音波式流量計の縦断面図、図６は同流量計の流路体の分解斜視図である。図５において、２１は入口部１０と出口部１１を機械的に接続し固定する接続体であり、ここでは接続体２１は入口部１０と出口部１１を金属材料で一体成形している。２２は接続体２１とＵ字体１２により囲まれて形成される空間部であり、流量演算部１４はこの空間部２２に収納されている。
【００２５】
図６において、２３は一体成形した流路体１７の第一開口部１８および第二開口部１９を封止するとともに空間部２２の一面を封鎖する金属材料で形成した第一封止体であり、２４は空間部２２の他面を封鎖する金属材料で形成した第二封止体である。
【００２６】
このように、外部との接続口である入口部１０および出口部１１を接続体２１で固定しているので、流量計を外部の配管などに取付ける時など大きな外力を加えても、高強度化された接続体２１により測定路４を有するＵ字体１２の変形を防止でき取付時の施工性および計測精度の信頼性が向上できる。また、接続体２１とＵ字体１２との間で形成した空間部２２に流量演算部１４を収納することでスペースの有効活用を図り流量計をより小型化できる。また流量演算部１４は接続体２１とＵ字体１２により必然的に４面を金属材料で囲うことができ、残りの２面を第一および第二封止体２３、２４で囲うだけで流量演算部１４はその全周面を外部からの電波などの外乱から遮蔽できる。特に第一封止体２３は流路体１７の封止体と兼用でき、外乱からの遮蔽構成の低コスト化と外乱の影響をなくして計測精度の信頼性を向上することができる。
【００２７】
（実施例５）
図７は本発明の実施例５の超音波式流量計の縦断面図である。図７において、２５は計測値、異常発生あるいは流量計への動作命令などを離れた場所に設けた外部ユニット２６と無線により送受信する無線送受信手段である。無線送受信手段２５は無線送受信手段本体２５ａと無線送受信手段アンテナ２５ｂを備え、外部ユニット２６は外部ユニット本体２６ａと外部アンテナ２６ｂを備えている。２７は無線送受信手段２５とＵ字体１２を覆う筐体である。この筐体２７は合成樹脂などの電波透過性材料で構成されるもので、無線送受信手段２５とＵ字体１２の他に開閉体９、一対の超音波振動子１３、流量演算部１４、などを覆っている。また、流量演算部１４および無線送受信手段２５の無線送受信手段本体２５ａは空間部２２に収納されるとともに封止体（図示せず）により外乱電波などから遮蔽されている。
【００２８】
このように、筐体２７は合成樹脂などの電波透過性材料にして無線送受信手段２５を筐体２７内に内蔵でき、筐体の外部に無線送受信手段を設ける場合に生じる外形寸法の拡大や部品数の増加が防止され、流量計の小型化と低コスト化ができる。また、Ｕ字体１２により流量計の強度が確保されるため、筐体は強度部材と考えなくて良く、材質の選択自由度、薄肉化、樹脂化などが実現でき、流量計の生産性の向上と軽量化による取扱い性の向上ができる。
【００２９】
（実施例６）
図８は本発明の実施例６の超音波式流量計の縦断面図である。図８において、２８は被測定流体の中に含まれる水分を凝縮液化させる凝縮促進部であり、一対の超音波振動子１３の上流側と下流側に設けられている。２９は凝縮促進部２８に熱的に連結された放熱部である。凝縮促進部２８としてペルチェ素子などの電子冷却手段の吸熱側を配置し、放熱部２９としてペルチェ素子などの電子冷却手段の放熱側を配置することで被測定流体中の水分を温度の低下した凝縮促進部２８で凝縮せしめるものである。このように測定路４あるいは超音波振動子１３よりも低温となる凝縮促進部２８を設けることで測定路４あるいは超音波振動子１３への水分の付着を防止して、水分が付着することによる超音波の送受信機能の劣化の発生をなくし、計測不能となる事態の防止および計測精度の劣化の発生を防止する。なお、凝縮促進部２８は一対の超音波振動子１３の上流側に設けることで十分であるが、被測定流体の流動が停止しているときに出口部１１側から自然対流などで逆流する可能性があることを考えると、一対の超音波振動子１３の下流側にも設ける方がより効果があるのは言うまでもない。また、測定路４を導入路５、導出路６より上方に配置した逆Ｕ字状にＵ字体１２を構成した方が効果が高いのは言うまでもない。
【００３０】
このように、被測定流体中の水分は凝縮促進部２８で凝縮液化されて低減されるため一対の超音波振動子１３への水分の結露付着が防止され、超音波振動子１３への水分の付着による超音波の受送信機能の劣化を防止して測定機能の確保および測定精度の確保に対する信頼性を向上できる。
【００３１】
（実施例７）
図９は本発明の実施例７の超音波式流量計の縦断面図である。図９において、３０は接続体２１の外表面に設けたフィンで、フィン３０の近くにある被測定流体の流路の内壁が熱的に対向して凝縮促進部２８として作用する。３１は特に強く凝縮促進部２８として作用させるため流路の内壁に設けた凝縮フィンであり、接続体２１を介して外表面に設けたフィン３０と熱的に連結されている。ここで、凝縮促進部２８はフィン３０により外気により冷やされて外気温度程度まで冷やされ、凝縮促進部２８を通る被測定流体中の水分の凝縮液化を促し、被測定流体の湿度が高くその露点温度が凝縮促進部２８の温度より高い場合は凝縮促進部２８で結露を生じさせる。
【００３２】
このように、外気温度と自然対流により冷却するため凝縮作用にエネルギーを使わず省電力化できる。また、流量計の外部に接する外表面積が広い接続体にさらに表面積を拡大するフィンを設けるため、このフィンに熱的に対向する流量計内の流路が外気温度により十分冷やされて凝縮作用を確実にして計測部への水分の付着を防止して計測の信頼性をより一層向上できる。また、接続体の外表面積が広いためフィンを設置する位置は加工し易い場所に任意に設定でき加工性を向上できる。また、さらにフィンを接続体の補強部として併用できるため、流量計の耐久性を向上できる。なお、流路の内壁に凝縮フィン３１がない場合でも、外表面に設けたフィン３０の近くにある流路の内壁は外気温度により冷却されるので凝縮促進部２８として作用するのは言うまでもなく、流路の内壁の加工が容易となるため、より生産性に優れた流量計が実現できる。
【００３３】
（実施例８）
図１０は本発明の実施例８の超音波式流量計の縦断面図である。図１０において、３２は測定路４の外周側に設けた断熱材であり、超音波振動子１３も覆うように設けている。この断熱材３２により測定路４の近傍を保温して凝縮促進部２８よりも測定路４の近傍の温度が低くなるのを防ぎ、測定路４および超音波振動子１３への結露を防止する。
【００３４】
このように、断熱材３２により測定路４が外気温度により他の部分より速く冷却されるのを防止して測定路４での内面の結露を防止して超音波振動子１３への水分の付着をなくすもので、超音波振動子１３への水分の付着による超音波の受送信特性の劣化を防止して流量測定の信頼性をより一層向上できる。
【００３５】
以上の説明から明らかなように本発明の各実施例における超音波式流量計によれば、次の効果が得られる。
【００３６】
矩形断面の測定路とこの測定路の上流側および下流側に接続した導入路と導出路とをＵ字状に形成したＵ字体と、Ｕ字体の導入路外側に設けた開閉体を有する流量制御室と、測定路の上流側および下流側に対向して設けた超音波振動子を備えることにより、測定路での流れ状態の二次元性が高められ、かつ超音波振動子間の超音波が測定路を伝播する距離を長く設定できるので、流れ状態の改善および超音波の伝播時間の解析精度の両面で測定精度を向上できる。また、上流側の超音波振動子と開閉体の配置の干渉をなくして測定路の流れ方向側の長さとＵ字体の奥行き方向の長さをそれぞれ短縮してアスペクト比の大きな矩形断面の測定路であっても流量計の小型化を実現できる。さらに、流量制御室の開閉体を取付ける穴および導入路に連通する穴は外側から容易に加工可能のため低コスト化ができる。
【００３７】
また、対向する超音波振動子は測定路の被測定流体の流れを横切るように流れ方向に対して所定の角度を設けて配置されているので、二次元性を高められた流れ状態に対してさらに矩形断面の長辺方向である流路幅Ｗにわたり平均の流速を計ることのため、より一層の高精度の流量測定ができる。また、上流側の超音波振動子と開閉体は偏心して配置されることおよび超音波振動子を測定路の上流側および下流側の端面に配置することにより、流量計の外形寸法に影響する高さ寸法Ｙおよび奥行き寸法Ｄを小さくして流量計のより一層の小型化ができる。
【００３８】
また、入口部、流量制御室、導入路、測定路、導出路、出口部を一体成形しているので、一体成形により被測定流体の流路である流路体が高強度に構成され測定部の歪みあるいは外力による変形などを防止して測定部の形状安定性が確保でき、流量計の耐久性および信頼性を向上できる。また、各部の一体成形により部品点数が削減でき、加工時間および組立時間などの低減により低コスト化が実現できる。
【００３９】
また、入口部、出口部を機械的に固定する接続体とＵ字体との間で形成した空間部に流量演算部を収納しているので、外部との接続口である入口部および出口部を接続体で固定しているので流量計の高強度化により取付の施工性および計測の信頼性を向上できる。また、接続体とＵ字体との間で形成した空間部に流量演算部を収納することで流量計をより小型化できる。また流量演算部は接続体とＵ字体により必然的に４面を金属材料で囲われるため、残りの２面を囲うだけで流量演算部はその全面を外部からの電波などの外乱から遮蔽でき、低コストで信頼性を向上できる。
【００４０】
また、無線送受信手段とＵ字体を覆う電波透過性材料で構成した筐体を備えているので、無線送受信手段を筐体内に内蔵でき、筐体の外部に無線送受信手段を設ける場合に生じる外形寸法の拡大や部品数の増加が防止されて流量計の小型化および低コスト化が向上できる。また、Ｕ字体により流量計の強度が確保されるため筐体は強度部材と考えなくて良く、材質の選択自由度、薄肉化、樹脂化などが実現でき、流量計の生産性の向上と軽量化による取扱い性の向上ができる。
【００４１】
また、超音波振動子の少なくとも上流側には被測定流体中の水分を凝縮液化させる凝縮促進部を設けているので、被測定流体中の水分は凝縮促進部で凝縮液化されて低減されるため超音波振動子への水分の結露付着が防止され、超音波の受送信機能の劣化を防止して測定機能の確保および測定精度の確保に対する信頼性を向上できる。
【００４２】
また、接続体の外表面にフィンを設けて凝縮促進部を構成しているので、外気温度と自然対流により冷却するため凝縮作用にエネルギーを使わず省電力化できる。また、外表面積が広い接続体の表面積をさらに拡大することで、流量計内の流路が外気温度により十分冷やされて凝縮作用が確実となり信頼性をより一層向上できる。また、接続体の外表面積が広いためフィンを設置する位置は加工し易い場所に任意に設定でき加工を向上できる。また、さらにフィンを接続体の補強部として併用できるため、流量計の耐久性を向上できる。
【００４３】
また、少なくとも測定路には断熱材を設けているので、測定路４が他の部分より速く冷やされるのを防いで測定路あるいは超音波振動子への水分の付着を防止し、超音波振動子への水分の付着による超音波の受送信特性の劣化を防止して流量測定の信頼性をより一層向上できる。
【００４４】
【発明の効果】
本発明の超音波式流量計は、測定路の断面アスペクト比および流路長さをそれぞれ大きく設定した上でコンパクトに構成できるため、測定精度が高く小型コンパクトな流量計を低コストで実現できる。
【図面の簡単な説明】
【図１】本発明の実施例１の超音波式流量計の縦断面図
【図２】図１のＡ−Ａ線断面図
【図３】本発明の実施例２の超音波式流量計の測定路を示し、図１のＢ−Ｂ線で切断した場合相当する断面図
【図４】本発明の実施例３の超音波式流量計の流路体の分解斜視図
【図５】本発明の実施例４の超音波式流量計の縦断面図
【図６】同流量計の流路体の分解斜視図
【図７】本発明の実施例５の超音波式流量計の縦断面図
【図８】本発明の実施例６の超音波式流量計の縦断面図
【図９】本発明の実施例７の超音波式流量計の縦断面図
【図１０】本発明の実施例８の超音波式流量計の縦断面図
【図１１】従来の超音波式流量計を説明する一部切欠断面斜視図
【符号の説明】
４測定路
５導入路
６導出路
７流量制御室
９開閉体
１０入口部
１１出口部
１２Ｕ字体
１３超音波振動子
１４流量演算部
２１接続体
２２空間部
２５無線送受信手段
２７筐体
２８凝縮促進部
３０フィン
３２断熱材[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an ultrasonic flow meter for measuring a flow rate.
[0002]
[Prior art]
  As a conventional measuring apparatus of this type, as shown in FIG. 11, the ultrasonic transducers 2 and 3 are arranged so as to face a part of a fluid flow path 1 having a rectangular cross section in a direction perpendicular to the flow. There has been a flow meter that measures the time until the ultrasonic wave emitted from the ultrasonic vibrator 2 is detected by the ultrasonic vibrator 3 and calculates the flow rate by calculating the fluid velocity from this time.
[0003]
[Problems to be solved by the invention]
  However, in the conventional flowmeter, the flow velocity distribution of the fluid in the flow path is formed as two-dimensionally as possible with a rectangular cross-sectional shape to improve the measurement accuracy. However, the aspect ratio (long side length H0 / short) The side length W0) is increased and flattened, and the flow path length is increased, so there are processing restrictions. Further, the rectangular flow path with a large aspect ratio increases the measurement accuracy and the flow of the fluid to be measured. There was a problem that the flow meter incorporating the control valve to be controlled cannot be made compact.
[0004]
[Means for Solving the Problems]
  In order to solve the above-mentioned problems, the present invention provides an introduction path and a lead-out path on the upstream side and downstream side of a measurement path having a rectangular cross section to form a U-shaped body, and the opening / closing body is accommodated outside the U-shaped path. A flow rate control chamber is provided, and ultrasonic transducers are arranged facing the upstream side and the downstream side of the measurement path.
[0005]
  According to the above invention, since the cross-sectional aspect ratio and the flow path length of the measurement path are set to be large and can be configured compactly, a small and compact flow meter with high measurement accuracy can be realized at low cost.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
  The present invention controls a measurement path having a rectangular cross section, an introduction path provided on the upstream side of the measurement path, a lead-out path provided on the downstream side of the measurement path, and a fluid to be measured flowing into the introduction path. An opening / closing body, a flow rate control chamber in communication with the introduction path and provided with the opening / closing body, an inlet portion provided on the upstream side of the flow rate control chamber, an outlet portion provided on the downstream side of the outlet path, and the measurement An ultrasonic transducer provided opposite to the upstream side and downstream side of the path, and a flow rate calculation unit that calculates a flow rate based on a signal from the ultrasonic transducer, the introduction path, the measurement path, the It has a U-shaped body in which the lead-out path is formed in a U-shape. The fluid to be measured in the measuring section is stabilized in flow by the introduction path and the outflow path provided on the upstream side and the downstream side, and the two-dimensionality of the flow state is enhanced by the large aspect ratio of the rectangular cross section. Ultrasonic transducers are installed on the upstream and downstream sides of the measurement unit, so that the distance that ultrasonic waves propagate through the measurement path can be set long, so that the change in the transmission time of ultrasonic waves due to the flow increases, improving the flow state and ultrasonic waves The measurement accuracy can be improved in terms of both the analysis accuracy of the propagation time. In addition, by providing a flow rate control chamber that houses the opening and closing body from the outside of the U-shaped body, the introduction path, the measurement path, and the lead-out path formed in a U shape, and providing ultrasonic transducers on the upstream side and the downstream side of the measurement path, The length of the measurement path in the flow direction side (left-right direction in FIG. 1) and the length in the U-shaped depth direction (paper surface direction in FIG. 1) are eliminated without interference between the arrangement of the ultrasonic transducer and the opening / closing body on the upstream side. Each can be shortened to reduce the size of the flow meter. Further, the hole for attaching the opening / closing body of the flow control chamber and the hole communicating with the introduction path can be easily processed from the outside, so that the cost can be reduced.
[0007]
  The opposing ultrasonic transducers are arranged at a predetermined angle with respect to the flow direction so as to cross the flow of the fluid to be measured in the measurement path. The ultrasonic wave emitted from the ultrasonic transducer measures the flow velocity over the long side direction of the cross section orthogonal to the flow, that is, the rectangular cross section, with respect to the fluid to be measured flowing through the measurement path. Since the flow rate is further averaged in the long side direction of the rectangular cross section with respect to the flow state whose two-dimensionality is improved by the cross section, the flow rate can be measured with higher accuracy. In addition, since it becomes easier to avoid interference in the arrangement of the upstream ultrasonic vibrator and the opening / closing body, the flow meter can be further miniaturized.
[0008]
  Further, the inlet part, the flow rate control chamber, the introduction path, the measurement path, the lead-out path, and the outlet part are integrally formed. Further, the cost reduction can be realized by reducing the number of parts and processing and assembling time by integrally forming each part. Further, since the flow path of the fluid to be measured is configured with high strength by integral molding and the shape stability of the flow measurement unit can be ensured, the durability and reliability of the flow meter can be improved.
[0009]
  Moreover, the connection body which fixes an inlet part and an outlet part mechanically, the space part formed between this connection body and a U-shaped body, and the flow volume calculating part are accommodated in this space part. And since the inlet part and outlet part which are the connection ports with the exterior are being fixed with the connection body, reliability can be improved by the strength improvement of a flowmeter. Further, the flow meter can be further downsized by housing the flow rate calculation unit in the space formed between the connection body and the U-shaped body. In addition, the flow rate calculation unit can inevitably enclose four sides with metal material by the connection body and U-shaped body, and the flow rate calculation unit can shield the entire surface from disturbances such as external radio waves just by surrounding the remaining two sides. Reliability can be improved at low cost.
[0010]
  Further, the apparatus includes a wireless transmission / reception means and a casing made of a radio wave transmitting material that covers the wireless transmission / reception means and the U-shaped body. And since the strength of the flow meter can be secured by the U-shaped body, the housing does not have to be considered as a strength member, and can be built without using a radio transmitting / receiving means outside the housing by using a radio wave transmitting material such as synthetic resin. The flow meter can be reduced in size and cost.
[0011]
  In addition, a condensation accelerating portion that condenses and liquefies moisture in the fluid to be measured is provided at least on the upstream side of the ultrasonic transducer. Then, moisture in the fluid to be measured is condensed and reduced by the condensation accelerating unit, so that condensation of moisture on the ultrasonic transducer is prevented, and transmission / reception of ultrasonic waves due to adhesion of moisture to the ultrasonic transducer is received. It is possible to improve the reliability of ensuring the measurement function and the measurement accuracy by preventing the deterioration of the function.
[0012]
  In addition, the condensation promoting part is configured by providing fins on the outer surface of the connection body. In addition, since a fin that further expands the surface area is provided on the connection body having a large outer surface area in contact with the outside of the flow meter, the flow path in the flow meter that is thermally opposed to the fin is sufficiently cooled by the outside air temperature, and the fluid to be measured When the inside humidity is high, condensation of moisture can be ensured and reliability can be further improved. Moreover, since the outer surface area of the connection body is large, the position where the fin is installed can be arbitrarily set at a place where it is easy to process, and the workability can be improved. Furthermore, since a fin can be used together as a reinforcement part of a connection body, durability of a flow meter can be improved.
[0013]
  Further, at least the measurement path is provided with a heat insulating material. Then, the heat insulating material prevents the measurement path from being cooled more quickly than the other parts by the outside air temperature, thereby eliminating condensation on the ultrasonic vibrator and further improving the reliability of the flow rate measurement.
[0014]
  Embodiments of the present invention will be described below with reference to the drawings.
[0015]
  Example 1
  1 is a longitudinal sectional view of an ultrasonic flowmeter according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. 1 and 2, reference numeral 4 denotes a measurement path in which a cross section orthogonal to the flow direction of the fluid to be measured has a rectangular shape with a long side having a flow path width W and a short side having a flow path height H. An introduction path provided on the upstream side of the measurement path 4 and in the direction of the flow path height H of the rectangular cross section, and 6 is a lead-out path provided on the downstream side of the measurement path 4 and on the same side as the introduction path 5. The introduction path 5 and the lead-out path 6 have dimensions close to the cross-sectional shape of the measurement path 4. Reference numeral 7 denotes a flow rate control chamber that communicates with the introduction path 5 through the opening / closing control port 8 and is positioned on the opposite side of the lead-out path 6. Reference numeral 9 denotes an opening / closing body provided in the flow rate control chamber 7, which has a valve portion 9a for opening / closing the opening / closing control port 8 and a drive portion 9b for driving the valve portion 9a. It is something to control. Reference numeral 10 denotes an inlet portion provided on the upstream side of the flow rate control chamber 7 and communicated with the flow rate control chamber 7, and a connecting means 10a such as a screw is provided on the outer peripheral portion thereof. Reference numeral 11 denotes an outlet provided on the downstream side of the lead-out path 6, and a connecting means 11a such as a screw is provided on the outer periphery thereof. Reference numeral 12 denotes a U-shaped body in which the introduction path 5, the measurement path 4, and the lead-out path 6 are formed in a U-shape, and is an inverted U shape in which the measurement path 4 is arranged at the top and the introduction path 5 and the lead-out path 6 are extended downward. I am doing. Reference numeral 13 denotes an ultrasonic transducer provided facing the upstream side and the downstream side of the measurement path 4, and reference numeral 14 denotes a flow rate calculation unit that calculates a flow rate based on a signal from the ultrasonic transducer 13. The flow rate calculation unit 14 includes a signal generation / processing unit 15 a for the ultrasonic transducer 13, a calculation unit 15 b, and an opening / closing control unit 16 that operates the opening / closing body 9.
[0016]
  Next, the operation will be described. First, at the start of use of the flowmeter, the opening / closing control unit 16 drives the drive unit 9b of the opening / closing body 9 to open the valve unit 9a from the opening / closing control port 8 (state shown in FIG. 1). The fluid to be measured flows from the inlet 10, enters the flow rate control chamber 7, and flows into the introduction path 5 through the opening / closing control port 8. The flow that has flowed into the introduction path 5 set to a shape and size close to the cross section of the measurement path 4 stabilizes the flow state and flows into the measurement path 4. In the measurement path 4, the cross-sectional shape having a large aspect ratio in which the flow path height H is set sufficiently small with respect to the flow path width W ensures two-dimensionality of the flow state in the cross section of the flow path. The flow exiting the measurement path 4 flows out from the outlet portion 11 through the lead-out path 6. Since the lead-out path 6 is set to have a shape and dimensions close to the cross section of the measurement path 4, the flow at the downstream end of the measurement path 4 ensures the above two-dimensionality. That is, the two-dimensionality of the flow state is ensured over the entire area of the measurement path 4 in the flow direction.
[0017]
  Next, the flow rate in the measurement path 4 is measured by transmitting and receiving ultrasonic waves between the pair of ultrasonic transducers 13 arranged to face each other by the action of the signal generation / processing unit 15a. At this time, the flow rate calculation unit 14 processes the signal measured between the pair of ultrasonic transducers 13 by the signal generation / processing unit 15a, and the calculation unit 15b further propagates the ultrasonic wave according to the flow velocity of the fluid to be measured. The flow rate is calculated more. The flow rate is calculated based on the flow velocity and the cross-sectional area of the measurement path 4. In the case where the flow rate of the fluid to be measured can be regarded as abnormal based on the measured flow rate, the open / close control unit 16 drives the open / close body 9 so that the valve portion 9b is brought into contact with the open / close control port 8 to be covered. The flow of the measurement fluid is stopped (not shown).
[0018]
  In this way, since the distance that crosses the flow between the pair of ultrasonic transducers 13 can be set to be as long as possible with respect to the measurement path 4, a change in the propagation time of ultrasonic waves can be reliably detected, and highly accurate measurement can be performed. it can. In addition, the two-dimensionality of the flow state of the fluid to be measured is enhanced over the entire area of the measurement path 4, and a pair of ultrasonic transducers 13 are provided on the upstream side and the downstream side of the measurement path 4. Can be set long, so that the measurement accuracy can be improved in both the improvement of the flow state and the propagation of ultrasonic waves. In addition, a flow rate control chamber 7 for accommodating the opening / closing body 9 is provided from the outside of the U-shaped body 12 in which the introduction path 5, the measurement path 4, and the lead-out path 6 are formed in a U shape, and a pair of ultrasonic transducers 13 are connected to the measurement path 4. By providing the upstream side and the downstream side, interference between the arrangement of the ultrasonic transducer 13 and the opening / closing body 9 on the upstream side is eliminated, and the length L on the flow direction side of the measurement path 4 and the U-shaped depth direction (FIG. 1). The size of the flow meter can be reduced by shortening the length in the paper direction). Further, the hole for attaching the opening / closing body 9 of the flow rate control chamber 7 and the opening / closing control port 8 communicating with the introduction path 5 can be easily processed from the outside, so that the cost can be reduced.
[0019]
  (Example 2)
  FIG. 3 shows a measurement path 4 of the ultrasonic flow meter according to the second embodiment of the present invention, and is a cross-sectional view corresponding to a case cut along the line BB in FIG. In FIG. 3, a pair of ultrasonic transducers 13 are provided on the upstream side and the downstream side of the measurement path 4 so as to face each other, and can measure over the entire flow direction of the fluid to be measured in the measurement path 4. A predetermined angle θ is arranged with respect to the flow direction (arrow C) so as to cross the flow of the fluid to be measured in the direction of the path width W.
[0020]
  Therefore, the ultrasonic wave transmitted from one ultrasonic transducer 13 flows over the flow path width W that is the long-side direction of the cross section orthogonal to the flow, that is, the rectangular cross section, with respect to the fluid to be measured flowing through the measurement path 4. It is received by the other ultrasonic transducer 13 across. Here, the flow state in the measurement path 4 can be improved in two-dimensionality by a rectangular cross section with a large aspect ratio, and further to measure the average flow velocity over the channel width W which is the long side direction of the rectangular cross section, It is possible to measure the flow rate with higher accuracy. Further, since the upstream ultrasonic transducer 13 and the opening / closing body 9 are arranged eccentrically, it becomes easier to avoid interference on the arrangement, and the height dimension Y (shown in FIG. 1) that affects the outer dimensions of the flowmeter. ) Can be reduced to reduce the size of the flow meter. Further, by arranging the pair of ultrasonic transducers 13 on the upstream and downstream end faces of the measurement path 4, the pair of ultrasonic transducers 13 can reduce the amount of protrusion in the direction of the channel width W, and the flow rate can be reduced. The depth dimension D that affects the external dimensions of the meter can be reduced. Therefore, the flow meter can be further reduced in size.
[0021]
  (Example 3)
  FIG. 4 is an exploded perspective view of the flow path body of the ultrasonic flowmeter according to the third embodiment of the present invention. In FIG. 4, reference numeral 17 denotes a flow path body in which an inlet portion 10, a U-shaped body 12 including a flow rate control chamber 7, an introduction path 5, a measurement path 4, and a lead-out path 6, and an outlet portion 11 are integrally formed of a metal material. . Reference numeral 18 denotes a first opening provided on one surface of the flow rate control chamber 7 of the flow path body 17, 19 denotes a second opening provided on one surface of the U-shaped body 12, and the first opening 18 and the second opening 19 are It is provided on the same surface side. Reference numeral 20 denotes a sealing body that seals the first opening 18 and the second opening 19. The sealing body 20 is a flow path body 17 via a packing material (not shown) or a sealing agent (not shown). Mounted on.
[0022]
  As described above, since the flow passage body 17 that is the flow passage of the fluid to be measured is formed with high strength by integral molding, the measurement portion can be prevented from being deformed or deformed by an external force, and the shape stability of the measurement portion can be ensured. The durability and reliability of the flow meter can be improved.
[0023]
  In addition, the number of parts can be reduced by integral molding of each part, and the cost can be reduced by reducing processing time and assembly time.
[0024]
  Example 4
  FIG. 5 is a longitudinal sectional view of an ultrasonic flowmeter according to a fourth embodiment of the present invention, and FIG. 6 is an exploded perspective view of a flow path body of the flowmeter. In FIG. 5, reference numeral 21 denotes a connecting body that mechanically connects and fixes the inlet portion 10 and the outlet portion 11. Here, the connecting body 21 integrally forms the inlet portion 10 and the outlet portion 11 with a metal material. Reference numeral 22 denotes a space formed by the connection body 21 and the U-shaped body 12, and the flow rate calculation unit 14 is accommodated in the space 22.
[0025]
  In FIG. 6, reference numeral 23 denotes a first sealing body formed of a metal material that seals the first opening 18 and the second opening 19 of the integrally formed flow path body 17 and seals one surface of the space 22. , 24 is a second sealing body formed of a metal material that seals the other surface of the space 22.
[0026]
  As described above, the inlet 10 and the outlet 11 which are connection ports to the outside are fixed by the connecting body 21, so that even when a large external force is applied, such as when the flow meter is attached to an external pipe or the like, the strength is increased. The deformed connection body 21 can prevent the U-shaped body 12 having the measurement path 4 from being deformed, and can improve the workability during mounting and the reliability of measurement accuracy. Further, by storing the flow rate calculation unit 14 in the space 22 formed between the connection body 21 and the U-shaped body 12, the space can be effectively used and the flow meter can be further downsized. Further, the flow rate calculation unit 14 can inevitably enclose four surfaces with a metal material by the connecting body 21 and the U-shaped body 12, and the flow rate calculation only by enclosing the remaining two surfaces with the first and second sealing bodies 23 and 24. The part 14 can shield the entire peripheral surface from disturbances such as external radio waves. In particular, the first sealing body 23 can also be used as the sealing body of the flow path body 17, and can reduce the cost of the shielding configuration from the disturbance and eliminate the influence of the disturbance, thereby improving the measurement accuracy reliability.
[0027]
  (Example 5)
  FIG. 7 is a longitudinal sectional view of an ultrasonic flowmeter according to the fifth embodiment of the present invention. In FIG. 7, reference numeral 25 denotes a wireless transmission / reception means for wirelessly transmitting / receiving a measured value, occurrence of an abnormality, or an operation command to the flow meter to / from an external unit 26 provided at a remote location. The wireless transmission / reception means 25 includes a wireless transmission / reception means body 25a and a wireless transmission / reception means antenna 25b, and the external unit 26 includes an external unit body 26a and an external antenna 26b. Reference numeral 27 denotes a housing that covers the wireless transmission / reception means 25 and the U-shaped body 12. The casing 27 is made of a radio wave transmitting material such as synthetic resin. In addition to the wireless transmission / reception means 25 and the U-shaped body 12, the opening / closing body 9, a pair of ultrasonic transducers 13, a flow rate calculation unit 14, and the like are provided. Covering. The flow rate calculation unit 14 and the wireless transmission / reception means body 25a of the wireless transmission / reception means 25 are housed in the space 22 and shielded from disturbance electric waves by a sealing body (not shown).
[0028]
  As described above, the casing 27 can be made of a radio wave transmitting material such as a synthetic resin so that the wireless transmission / reception means 25 can be built in the casing 27. The increase in the number is prevented, and the flow meter can be reduced in size and cost. Moreover, since the strength of the flow meter is ensured by the U-shaped body 12, the housing does not have to be considered as a strength member, and the degree of freedom of material selection, thinning, resinization, etc. can be realized, improving the productivity of the flow meter. And the handleability can be improved by weight reduction.
[0029]
  (Example 6)
  FIG. 8 is a longitudinal sectional view of an ultrasonic flowmeter according to the sixth embodiment of the present invention. In FIG. 8, reference numeral 28 denotes a condensation accelerating portion that condenses and liquefies moisture contained in the fluid to be measured, and is provided on the upstream side and the downstream side of the pair of ultrasonic transducers 13. Reference numeral 29 denotes a heat dissipating part thermally connected to the condensation promoting part 28. Condensation with reduced temperature of moisture in the fluid to be measured by disposing the heat absorption side of the electronic cooling means such as the Peltier element as the condensation promoting part 28 and the heat dissipation side of the electronic cooling means such as the Peltier element as the heat dissipation part 29 It is condensed by the promotion unit 28. Thus, by providing the condensation accelerating portion 28 having a temperature lower than that of the measurement path 4 or the ultrasonic vibrator 13, the moisture can be prevented from adhering to the measurement path 4 or the ultrasonic vibrator 13, and the moisture can adhere. The occurrence of deterioration of the ultrasonic transmission / reception function is eliminated, the situation in which measurement becomes impossible, and the occurrence of deterioration in measurement accuracy are prevented. It is sufficient to provide the condensation accelerating portion 28 on the upstream side of the pair of ultrasonic transducers 13, but it is possible to reversely flow from the outlet portion 11 side by natural convection when the flow of the fluid to be measured is stopped. Needless to say, it is needless to say that it is more effective to provide it on the downstream side of the pair of ultrasonic transducers 13. Needless to say, it is more effective to configure the U-shaped body 12 in an inverted U shape in which the measurement path 4 is disposed above the introduction path 5 and the lead-out path 6.
[0030]
  In this way, moisture in the fluid to be measured is condensed and reduced by the condensation accelerating unit 28, and therefore, moisture condensation on the pair of ultrasonic transducers 13 is prevented, and moisture on the ultrasonic transducers 13 is prevented. It is possible to improve the reliability of ensuring the measurement function and ensuring the measurement accuracy by preventing the ultrasonic wave receiving / transmitting function from being deteriorated due to adhesion.
[0031]
  (Example 7)
  FIG. 9 is a longitudinal sectional view of an ultrasonic flowmeter according to a seventh embodiment of the present invention. In FIG. 9, 30 is a fin provided on the outer surface of the connection body 21, and the inner wall of the flow path of the fluid to be measured near the fin 30 is thermally opposed to act as the condensation promoting portion 28. Reference numeral 31 denotes a condensation fin provided on the inner wall of the flow path so as to act particularly strongly as the condensation accelerating portion 28, and is thermally coupled to the fin 30 provided on the outer surface via the connection body 21. Here, the condensation accelerating portion 28 is cooled by the outside air by the fins 30 and is cooled to about the outside air temperature. The condensation accelerating portion 28 promotes the liquefaction of the moisture in the fluid to be measured that passes through the condensation accelerating portion 28, and the humidity of the fluid to be measured is high. When the temperature is higher than the temperature of the condensation promoting unit 28, the condensation promoting unit 28 causes condensation.
[0032]
  In this way, since cooling is performed by the outside air temperature and natural convection, power can be saved without using energy for the condensing action. In addition, since fins that further expand the surface area are provided on the connection body having a large external surface area that contacts the outside of the flow meter, the flow path in the flow meter that is thermally opposed to the fins is sufficiently cooled by the outside air temperature to perform the condensation action. The reliability of measurement can be further improved by reliably preventing moisture from adhering to the measurement unit. Moreover, since the outer surface area of the connection body is large, the position where the fin is installed can be arbitrarily set at a place where it is easy to process, and the workability can be improved. Further, since the fins can be used together as the reinforcing part of the connection body, the durability of the flow meter can be improved. In addition, even when there is no condensation fin 31 on the inner wall of the flow path, it goes without saying that the inner wall of the flow path near the fins 30 provided on the outer surface is cooled by the outside air temperature and thus acts as the condensation promoting portion 28. Since the processing of the inner wall of the flow path becomes easy, a flow meter with higher productivity can be realized.
[0033]
  (Example 8)
  FIG. 10 is a longitudinal sectional view of an ultrasonic flowmeter according to the eighth embodiment of the present invention. In FIG. 10, 32 is a heat insulating material provided on the outer peripheral side of the measurement path 4, and is provided so as to cover the ultrasonic transducer 13. This heat insulating material 32 keeps the vicinity of the measurement path 4 warm to prevent the temperature in the vicinity of the measurement path 4 from becoming lower than the condensation accelerating portion 28 and prevent condensation on the measurement path 4 and the ultrasonic transducer 13.
[0034]
  In this way, the heat insulating material 32 prevents the measurement path 4 from being cooled faster than the other portions due to the outside air temperature, prevents condensation on the inner surface of the measurement path 4, and attaches moisture to the ultrasonic transducer 13. Therefore, it is possible to further prevent the deterioration of the ultrasonic transmission / reception characteristics due to the adhesion of moisture to the ultrasonic transducer 13 and further improve the reliability of the flow rate measurement.
[0035]
  Less thanAs is apparent from the above description, the present inventionIn each exampleAccording to the ultrasonic flow meter, the following effects can be obtained.
[0036]
  Flow rate control having a U-shaped body in which a measurement path having a rectangular cross section, an introduction path connected to the upstream side and the downstream side of the measurement path, and a lead-out path are formed in a U shape, and an opening / closing body provided outside the introduction path of the U shape By providing the chamber and ultrasonic transducers provided facing the upstream and downstream sides of the measurement path, the two-dimensionality of the flow state in the measurement path is improved, and the ultrasonic waves between the ultrasonic transducers are Since the distance propagating through the measurement path can be set long, the measurement accuracy can be improved in terms of both the improvement of the flow state and the analysis accuracy of the ultrasonic wave propagation time. In addition, the measurement path of the rectangular cross section having a large aspect ratio is obtained by eliminating the interference between the arrangement of the ultrasonic transducer on the upstream side and the opening / closing body and shortening the length in the flow direction side of the measurement path and the length in the depth direction of the U-shaped body. Even so, the flow meter can be downsized. Furthermore, since the hole for attaching the opening / closing body of the flow control chamber and the hole communicating with the introduction path can be easily processed from the outside, the cost can be reduced.
[0037]
  Further, since the opposing ultrasonic transducers are arranged at a predetermined angle with respect to the flow direction so as to cross the flow of the fluid to be measured in the measurement path, the flow state with improved two-dimensionality Furthermore, since the average flow velocity is measured over the flow path width W which is the long side direction of the rectangular cross section, the flow rate can be measured with higher accuracy. In addition, the upstream ultrasonic transducer and the opening / closing body are arranged eccentrically, and the ultrasonic transducer is arranged on the upstream and downstream end faces of the measurement path, thereby increasing the external dimensions of the flowmeter. The size Y and the depth dimension D can be reduced to further reduce the size of the flow meter.
[0038]
  In addition, since the inlet part, flow control chamber, introduction path, measurement path, lead-out path, and outlet part are integrally formed, the flow path body that is the flow path of the fluid to be measured is configured with high strength by the integral molding, and the measurement part Therefore, it is possible to ensure the shape stability of the measuring part by preventing distortion or deformation due to external force, and to improve the durability and reliability of the flowmeter. In addition, the number of parts can be reduced by integral molding of each part, and the cost can be reduced by reducing processing time and assembly time.
[0039]
  In addition, since the flow rate calculation unit is housed in the space formed between the connection body and the U-shaped body that mechanically fixes the entrance and exit, the entrance and exit that are connection ports with the outside are provided. Since it is fixed with a connection body, the installation workability and measurement reliability can be improved by increasing the strength of the flowmeter. Further, the flow meter can be further downsized by housing the flow rate calculation unit in the space formed between the connection body and the U-shaped body. In addition, since the flow rate calculation unit is inevitably surrounded by a metal material with the connection body and the U-shaped body, the flow rate calculation unit can shield the entire surface from disturbances such as external radio waves only by surrounding the remaining two surfaces. Reliability can be improved at low cost.
[0040]
  In addition, since the wireless transmission / reception means and the casing made of a radio wave transmitting material covering the U-shaped body are provided, the wireless transmission / reception means can be built in the casing, and the external dimensions generated when the wireless transmission / reception means is provided outside the casing. The increase in the number of parts and the increase in the number of parts can be prevented, and the size and cost of the flow meter can be improved. In addition, since the strength of the flow meter is secured by the U-shaped body, the housing does not have to be considered as a strength member, and it is possible to realize freedom of material selection, thinning, resinization, etc., improving flow meter productivity and light weight The handleability can be improved by making it easier.
[0041]
  In addition, since the condensation accelerating portion that condenses and liquefies the moisture in the fluid to be measured is provided at least upstream of the ultrasonic vibrator, the moisture in the fluid to be measured is reduced by being condensed and liquefied by the condensation accelerating portion. It is possible to prevent moisture from adhering to the ultrasonic vibrator and to prevent deterioration of the ultrasonic wave transmission / reception function, thereby improving the reliability of ensuring the measurement function and ensuring the measurement accuracy.
[0042]
  In addition, since the condensation promoting portion is formed by providing fins on the outer surface of the connection body, cooling is performed by the outside air temperature and natural convection, so that energy can be saved without using energy for the condensation action. Further, by further expanding the surface area of the connection body having a large outer surface area, the flow path in the flowmeter is sufficiently cooled by the outside air temperature, and the condensing action is ensured, thereby further improving the reliability. Further, since the outer surface area of the connection body is large, the position where the fin is installed can be arbitrarily set at a place where it is easy to process, and the processing can be improved. Further, since the fins can be used together as the reinforcing part of the connection body, the durability of the flow meter can be improved.
[0043]
  In addition, since at least the measurement path is provided with a heat insulating material, the measurement path 4 is prevented from being cooled faster than the other parts, and adhesion of moisture to the measurement path or the ultrasonic vibrator is prevented. It is possible to further improve the reliability of flow rate measurement by preventing deterioration of ultrasonic transmission / reception characteristics due to moisture adhering to the surface.
[0044]
【The invention's effect】
  Since the ultrasonic flowmeter of the present invention can be configured compactly after setting the cross-sectional aspect ratio and the flow path length of the measurement path to be large, a small and compact flowmeter with high measurement accuracy can be realized at low cost.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an ultrasonic flowmeter according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3 shows a measurement path of an ultrasonic flowmeter according to a second embodiment of the present invention, and is a cross-sectional view corresponding to a case cut along the line BB in FIG.
FIG. 4 is an exploded perspective view of a flow path body of an ultrasonic flowmeter according to a third embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of an ultrasonic flowmeter according to a fourth embodiment of the present invention.
FIG. 6 is an exploded perspective view of the flow channel body of the flow meter.
FIG. 7 is a longitudinal sectional view of an ultrasonic flowmeter according to a fifth embodiment of the present invention.
FIG. 8 is a longitudinal sectional view of an ultrasonic flowmeter according to a sixth embodiment of the present invention.
FIG. 9 is a longitudinal sectional view of an ultrasonic flowmeter according to a seventh embodiment of the present invention.
FIG. 10 is a longitudinal sectional view of an ultrasonic flowmeter according to an eighth embodiment of the present invention.
FIG. 11 is a partially cutaway sectional perspective view illustrating a conventional ultrasonic flowmeter.
[Explanation of symbols]
  4 measurement paths
  5 introduction routes
  6 Derivation path
  7 Flow control room
  9 Opening and closing body
  10 Entrance
  11 Exit
  12 U font
  13 Ultrasonic vibrator
  14 Flow rate calculator
  21 connection body
  22 Space
  25 Wireless transmission / reception means
  27 Case
  28 Condensation promotion part
  30 fins
  32 Insulation

Claims

A measurement path having a rectangular cross section; an introduction path provided on the upstream side of the measurement path; a lead-out path provided on the downstream side of the measurement path; an open / close body that controls the fluid to be measured flowing into the introduction path; A flow rate control chamber communicated with the introduction path and provided with the opening / closing body, an inlet portion provided on the upstream side of the flow rate control chamber, an outlet portion provided on the downstream side of the lead-out path, and an upstream side of the measurement path And an ultrasonic transducer provided facing the downstream side, and a flow rate calculation unit for calculating a flow rate based on a signal from the ultrasonic transducer, and the introduction path, the measurement path, and the derivation path are defined as U have a U font formed in shape, the inlet, the flow control chamber, the introduction path, the measurement path, said outlet passage, and integrally molding the outlet portion, surrounded the flow control chamber by said U font An ultrasonic flow meter attached to the introduction path outside the formed space .

A measurement path having a rectangular cross section; an introduction path provided on the upstream side of the measurement path; a lead-out path provided on the downstream side of the measurement path; an open / close body that controls the fluid to be measured flowing into the introduction path; A flow rate control chamber communicated with the introduction path and provided with the opening / closing body, an inlet portion provided on the upstream side of the flow rate control chamber, an outlet portion provided on the downstream side of the lead-out path, and an upstream side of the measurement path And an ultrasonic transducer provided facing the downstream side, and a flow rate calculation unit for calculating a flow rate based on a signal from the ultrasonic transducer, and the introduction path, the measurement path, and the derivation path are defined as U A U-shaped body formed in a letter shape, a connection body for mechanically fixing the inlet portion and the outlet portion, a space portion formed between the connection body and the U-shape, and a flow rate calculation in the space portion Ultrasonic flow meter containing the part .

The ultrasonic flow meter according to claim 1 or 2 , further comprising: a wireless transmission / reception means; and a casing made of a radio wave transmitting material that covers the wireless transmission / reception means and the U-shaped body.

The ultrasonic flow meter according to any one of claims 1 to 3 , wherein a condensation accelerating portion that condenses and liquefies moisture in the fluid to be measured is provided at least upstream of the ultrasonic transducer.

The ultrasonic flowmeter according to claim 4 , wherein the condensation accelerating portion is configured by providing fins on the outer surface of the connection body.

Ultrasonic flowmeter according to any one of claims 1 to 5 provided with insulation on at least the measurement path.