JP3857959B2

JP3857959B2 - Flowmeter

Info

Publication number: JP3857959B2
Application number: JP2002176343A
Authority: JP
Inventors: 忠幸南; 泰宏藤井; 幸雄木村; 徳行鍋島
Original assignee: Osaka Gas Co Ltd; Aichi Tokei Denki Co Ltd; Toho Gas Co Ltd
Current assignee: Osaka Gas Co Ltd; Aichi Tokei Denki Co Ltd; Toho Gas Co Ltd
Priority date: 2002-06-17
Filing date: 2002-06-17
Publication date: 2006-12-13
Anticipated expiration: 2022-06-17
Also published as: JP2004020394A

Description

【０００１】
【発明の属する技術分野】
本発明は、都市ガスなどの流体の流量を計測する流量計に関するものである。
【０００２】
【従来の技術】
従来、ガスの使用量を計測するガスメータに用いる流量計として、超音波が流体中を伝搬する時間（伝搬時間）に基づいて流体の流速を検出し、検出した流速に流路の断面積を乗じて流量を測定する超音波式の流量計が周知である。図５は従来の超音波式の流量計（ガスメータ）の一例を示す概略構成図である。この流量計は、ガスが通過するガス流路１と、ガス流路１の途中に設けられる測定路２’と、測定路２’の上流側と下流側にそれぞれ配設されて超音波の送受波を行う一対の送受波器３Ａ，３Ｂと、送受波器３Ａ、３Ｂを駆動して超音波の送受波を行わせる送受波器駆動部４と、測定路２’の上流側に設けられる遮断弁５と、遮断弁５を駆動する遮断弁駆動部６と、測定路２’の下流側に設けられて流体の圧力を測定する圧力測定部７と、ガスの使用量（積算流量）等を表示する表示部８と、送受波器駆動部４、遮断弁駆動部６並びに表示部８を制御する制御回路部９’と、制御回路部９’の動作に必要となる各種のデータを記憶するメモリ部１０とを備える。そして、制御回路部９’が所定の時間間隔Ｔで送受波器駆動部４に駆動信号を出力することにより、送受波器駆動部４により一対の送受波器３Ａ，３Ｂから交互に超音波を送波させ、上流側の送受波器３Ａから下流側の送受波器３Ｂに向かって超音波を送波したときの超音波の伝搬時間ｔ１と、下流側の送受波器３Ｂから上流側の送受波器３Ａに向かって超音波を送波したときの超音波の伝搬時間ｔ２とを制御回路部９’にて計測し、次式により流体の流速ｖを求める。
【０００３】
ｖ＝｛Ｌ／（２ｃｏｓθ）｝×（１／ｔ１−１／ｔ２）
但し、Ｌは送受波器３Ａ，３Ｂの間の距離、θは測定路２’の中心軸に対する送受波器３Ａ，３Ｂの傾き角である。このようにして求めた流速ｖに測定路２’の断面積Ｓを乗じることで流体の流量（瞬時流量）ｑが求められ（ｑ＝ｖ×Ｓ〔ｍ^３／ｈ〕）、さらに瞬時流量ｑに時間間隔Ｔを乗じることで積算流量Ｑが求められる。
【０００４】
また制御回路部９’は、測定した流量ｑが想定される流量よりも過大である場合や所定の流量ｑが予め設定される継続時間を超えて測定される場合にガスの使用に何らかの異常が生じていると判断し、遮断弁駆動部６を制御して遮断弁５を閉じることによりガスの供給を停止したり、あるいは流量ｑがほぼゼロとなる時間帯が３０日間に一度も存在しない場合にガスメータより下流側の内管設備に漏洩（ガス漏れ）が生じていると判断して表示部８に警報を表示したり、あるいは所定間隔（例えば１０秒毎）で圧力測定部７により流体の圧力を測定し、流体の圧力が異常に上昇又は下降した場合にも何らかの異常が発生しているものと判断し、遮断弁駆動部６を制御して遮断弁５を閉じることによりガスの供給を停止する機能を有している。
【０００５】
【発明が解決しようとする課題】
ところで、流量測定の安定性向上のために、互いに並列に接続される複数の測定路を設け、各測定路毎に一対の送受波器を配設し、個々の測定路における流量を順番に測定してそれらの測定値の総和を全体の流量とする流量計が提供されている。このように複数の測定路を有する流量計において、何れかの測定路で送受波器の故障、測定路の変形又は異物の侵入、あるいは送受波器を接続する配線の断線などの異常が発生した場合に全体の流量が正確に測定できなくなるから、そのような異常は早期に検出する必要がある。しかしながら、複数の測定路における流量の測定は所定の測定周期で順番に行われるために異常の発生している測定路の特定に時間がかかるという問題がある。
【０００６】
また、大流量を測定するための第１の測定路と、第１の測定路に直列に接続される小流量を測定するための第２の測定路と、第２の測定路を流れる流体の流量が所定の基準値を上回る場合に開放して第２の測定路をバイパスする切替弁とを備え、流体の流量が上記基準値を上回る場合、すなわち流量が大きい場合には切替弁が開放して第２の測定路がバイパスされ、第１の測定路において流量を測定し、流量が上記基準値を下回る場合、すなわち流量が小さい場合には切替弁が閉じて第２の測定路において流量を測定するようにした流量計が提供されている。なお、第１の測定路を並列に接続された複数の測定路で構成した流量計も提供されている。このように大流量用と小流量用の２種類の測定路を有する流量計においても、何れかの測定路で送受波器の故障、測定路の変形又は異物の侵入、あるいは送受波器を接続する配線の断線などの異常が発生した場合に流量が正確に測定できなくなるから、そのような異常は早期に検出する必要がある。
【０００７】
本発明は上記事情に鑑みて為されたものであり、その目的は、複数の測定路の中から異常が発生している測定路を早期に検出することができる流量計を提供することにある。
【０００８】
【課題を解決するための手段】
請求項１の発明は、上記目的を達成するために、少なくとも断面積が等しく且つ互いに並列に接続される複数の測定路と、各測定路毎に設けられ当該測定路に流れる流体の流速を検出する複数の流速検出手段と、各流速検出手段に所定の測定周期で順番に流速の検出を行わせる制御手段と、各流速検出手段で検出する流速から各々の測定路における流体の流量を求めるとともに各測定路における流量の総和を求めて流体の流量を測定する流量演算手段と、前記測定周期よりも充分に短い周期で各流速検出手段に順番に流速の検出を行わせるとともに流量演算手段により求めた各測定路における流量を比較し、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に当該流量の測定路又は流速検出手段に異常が生じていると判断する異常検出手段とを備えたことを特徴とし、互いに並列に接続された複数の測定路にはほぼ同じ流量の流体が流れることとなるから、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に当該流量の測定路又は流速検出手段に、流速検出手段の故障や測定路の変形又は異物の侵入あるいは流速検出手段を流量演算手段に接続する配線の断線などの異常が発生していると判断することができ、しかも、このように異常発生を判断する際の流量の測定を通常の測定周期よりも充分に短い周期で行うことで複数の測定路の中から異常が発生している測定路を早期に検出することができる。
【０００９】
請求項２の発明は、上記目的を達成するために、測定流量域が比較的に大きい第１の測定路と、測定流量域が比較的に小さく且つ第１の測定路と直列に接続される第２の測定路と、第２の測定路を流れる流体の流量が所定の基準値を上回る場合に開放して第２の測定路をバイパスする切替弁と、第１の測定路に流れる流体の流速を検出する第１の流速検出手段と、第２の測定路に流れる流体の流速を検出する第２の流速検出手段と、切替弁が開いているときには第１の流速検出手段に所定の測定周期で流速の検出を行わせるとともに切替弁が閉じているときには第２の流速検出手段に所定の測定周期で流速の検出を行わせる制御手段と、第１及び第２の流速検出手段で検出する流速からそれぞれ第１又は第２の測定路における流体の流量を求める流量演算手段と、前記測定周期よりも充分に短い周期で第１及び第２の流量検出手段に順番に流速の検出を行わせるとともに流量演算手段により求めた第１又は第２の測定路における流量の少なくとも何れか一方が所定の基準値を下回り、且つ第１の測定路における流量と第２の測定路における流量の差が所定のしきい値を越えた場合に第１並びに第２の測定路又は第１並びに第２の流速検出手段の少なくとも何れか一方に異常が生じていると判断する異常検出手段とを備えたことを特徴とし、直列に接続された第１及び第２の測定路には同じ流量の流体が流れることとなるから、第１及び第２の測定路における流量の違いに基づいて、第１又は第２の流速検出手段の故障や第１又は第２の測定路の変形又は異物の侵入あるいは第１又は第２の流速検出手段を流量演算手段に接続する配線の断線などの異常が発生していると判断することができ、しかも、このように異常発生を判断する際の流量の測定を通常の測定周期よりも充分に短い周期で行うことで異常が発生している測定路を早期に検出することができる。
【００１０】
請求項３の発明は、請求項２の発明において、少なくとも断面積が等しい複数の測定路を互いに並列に接続して第１の測定路が構成され、第１の測定路を構成する各測定路毎に設けられる複数の流速検出手段により第１の流速検出手段が構成されてなり、制御手段は、第１の流速検出手段を構成する各流速検出手段に所定の測定周期で順番に流速の検出を行わせ、流量演算手段は、第１の流速検出手段を構成する各流速検出手段で検出する流速から第１の測定路を構成する各々の測定路における流体の流量を求めるとともに各測定路における流量の総和を求めて第１の測定路における流体の流量を測定し、異常検出手段は、前記測定周期よりも充分に短い周期で第１の流速検出手段を構成する各流速検出手段に順番に流速の検出を行わせるとともに流量演算手段により求めた第１の測定路を構成する各測定路における流量を比較し、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に当該流量の測定路又は第１の流速検出手段を構成する流速検出手段に異常が生じていると判断することを特徴とし、第１の測定路を構成する互いに並列接続された複数の測定路における流量の総和として大きな流量を測定し、これら複数の測定路からなる第１の測定路に直列に接続された第２の測定路において小さな流量を測定する場合において、第１の測定路を構成する複数の測定路や第２の測定路、あるいは第１の流速検出手段を構成する複数の流速検出手段や第２の流速検出手段に発生する異常を早期に検出することができる。
【００１１】
請求項４の発明は、請求項３の発明において、異常検出手段は、流量演算手段により求めた第１の測定路を構成する各測定路における流量を比較し、他の測定路における流量との差が所定のしきい値を越える流量が存在しない場合に第２の測定路又は第２の流速検出手段に異常が生じていると判断することを特徴とし、第２の測定路又は第２の流速検出手段に発生する異常を早期に検出することができる。
【００１２】
請求項５の発明は、請求項１又は３又は４の発明において、３つ以上の測定路を備え、異常検出手段は、多数決により異常の生じた測定路を特定することを特徴とし、請求項１又は３又は４の発明と同様の作用を奏する。
【００１３】
請求項６の発明は、請求項１〜４の何れかの発明において、各測定路への流体の流入を遮断する遮断弁と、データを記憶する記憶手段とを備え、流量演算手段は、測定周期毎の流量の積算値を求める処理を行い、異常検出手段は、同一の測定路について所定回数以上の異常発生を検出した場合に当該測定路を特定する番号、異常と判断した時刻及び当該時刻における積算値の少なくとも何れか１つのデータを記憶手段に記憶するとともに、異常発生の報知、遮断弁の閉止、あるいは流量演算手段による流量の積算値を求める処理の停止のうちの少なくとも何れか１つを実行させることを特徴とし、異常発生により積算値の誤差が増大するのを防ぐとともに、異常が発生した測定路の特定や全ての測定路において流量が正常に測定されていた期間、あるいはその期間までの積算値等を知ることができる。
【００１４】
請求項７の発明は、請求項１又は２又は３の発明において、異常検出手段は、予め決めた条件が満たされたときに異常検出を行うことを特徴とし、例えば予め決められた測定回数や測定時間、あるいは測定間隔毎に異常検出を行うことができる。
【００１５】
【発明の実施の形態】
（実施形態１）
図１は本実施形態の流量計を示すブロック図、図２は流量計の内部構造を模式的に示した概略図である。但し、図５に示した従来例と共通の構成要素には同一の符号を付して説明を省略する。
【００１６】
この流量計は、図２に示すように一端側に流体（ガス）の流入口２１が設けられるとともに他端側に流出口２２が設けられたハウジング２０を有している。ハウジング２０の内部は隔壁２３，２４によって３つの室（第１室２５，第２室２６，第３室２７）に仕切られており、第１室２５が流入口２１と連通し、第３室２７が流出口２２と連通する。第１室２５と第２室２６を仕切る隔壁２３には遮断弁５が設けられ、第１室２５から第２室２６への流体の移動が遮断し得るように構成されている。また、第２室２６と第３室２７を仕切る隔壁２４を貫通するように複数（Ｎ個）の測定路２_１〜２_Ｎが並設されており、これら複数の測定路２_１〜２_Ｎは第２室２６と第３室２７の間で互いに並列に接続されている。さらに、各測定路２_１〜２_Ｎは同一寸法及び同一形状に形成されており、図２では図示を省略するが、各測定路２_１〜２_Ｎの上流側と下流側にそれぞれ一対の送受波器３Ａ_１，３Ｂ_１、…、３Ａ_Ｎ，３Ｂ_Ｎが配設されている。而して、流入口２１から第１室２５に導入された流体は遮断弁５を介して第２室２６に移動し、Ｎ個の測定路２_１〜２_Ｎを均等に通って第３室２７へ移動して流出口２２からハウジング２０の外へ導出される。なお、第３室２７には流体の圧力変動を監視するために圧力測定部７が設けてある。
【００１７】
図１に示すように本実施形態の流量計は、各測定路２_１〜２_Ｎ毎に設けられた各一対の送受波器３Ａ_１，３Ｂ_１、…、３Ａ_Ｎ，３Ｂ_Ｎを駆動して超音波の送受波を行わせる送受波器駆動部４と、遮断弁５を駆動する遮断弁駆動部６と、測定した流量（積算流量）等を表示する表示部８と、送受波器駆動部４、遮断弁駆動部６並びに表示部８を制御する制御回路部９と、制御回路部９の動作に必要となる各種のデータを記憶するメモリ部１０とを備える。一方の送受波器３Ａ_１〜３Ａ_Ｎは各測定路２_１〜２_Ｎの上流側に配設され、他方の送受波器３Ｂ_１〜３Ｂ_Ｎは各測定路２_１〜２_Ｎの下流側に配設されるとともに対となる送受波器３Ａ_１〜３Ａ_Ｎと対向する。送受波器駆動部４は各送受波器３Ａ_１〜３Ａ_Ｎ，３Ｂ_１〜３Ｂ_Ｎを個別に駆動して超音波の送受波を行わせるものであって、一方の送受波器から送波された超音波を対となる他方の送受波器で受波したときにその旨を知らせる信号（受波信号）を制御回路部９に出力する。
【００１８】
制御回路部９はマイクロコンピュータを主構成要素とするものであって、所定の測定周期（例えば、２秒）で送受波器駆動部４に駆動信号を出力することにより、送受波器駆動部４により各一対の送受波器３Ａ_１，３Ｂ_１、…、３Ａ_Ｎ，３Ｂ_Ｎから交互に超音波を送波させ、上流側の送受波器３Ａ_１〜３Ａ_Ｎから下流側の送受波器３Ｂ_１〜３Ｂ_Ｎに向かって超音波を送波したときの超音波の伝搬時間ｔ１_１〜ｔ１_Ｎと、下流側の送受波器３Ｂ_１〜３Ｂ_Ｎから上流側の送受波器３Ａ_１〜３Ａ_Ｎに向かって超音波を送波したときの超音波の伝搬時間ｔ２_１〜ｔ２_Ｎとを駆動信号の出力タイミングと送受波器駆動部４からの受波信号の入力タイミングとに基づいて計測することにより、従来例で説明したように流体の流量（瞬時流量）を測定する。すなわち、制御回路部９はＮ個の測定路２_１〜２_Ｎにおける流量を上記測定周期で順番に測定し、全ての測定路２_１〜２_Ｎにおける流量の総和を求めることで全体の流量を算出するとともに、かかる全体流量の測定を所定の時間間隔で行い、全体流量と時間間隔を乗算することで積算流量を求めており、制御手段と流量演算手段を兼ねている。
【００１９】
表示部８はＬＥＤ（発光ダイオード）やＬＣＤ（液晶ディスプレイ）のような表示デバイスを有し、制御回路部９から出力される信号に基づいて表示デバイスを駆動することにより積算流量の値や後述する警報表示等の各種の表示を行うものである。また、記憶手段たるメモリ部１０はＥＥＰＲＯＭのような書き換え可能な不揮発性メモリで構成されており、上記測定周期や測定路２_１〜２_Ｎの断面積等の設定データの他に、後述するように異常発生時の各種データを記憶する。
【００２０】
ところで、このように複数の測定路２_１〜２_Ｎで個別に流量を測定する構成の場合、何れかの測定路２_ｉで送受波器３Ａ_ｉ，３Ｂ_ｉの故障、測定路２_ｉの変形又は異物の侵入、あるいは送受波器３Ａ_ｉ，３Ｂ_ｉを送受波器駆動部４と接続する配線の断線などの異常が発生した場合に全体の流量が正確に測定できなくなり、しかも、そのような異常の発生を見過ごして測定を継続した場合には、積算流量の誤差が時間とともに累積されてしまうことになる。
【００２１】
そこで本実施形態においては、制御回路部９が測定周期よりも充分に短い周期（例えば、０．１秒）で測定路２_１〜２_Ｎ毎の流量の測定を行うとともに各測定路２_１〜２_Ｎにおける流量を比較し、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に当該流量の測定路に上述のような異常が生じていると判断するようにしており、制御回路部９により異常検出手段を構成している。例えば、測定路２_２〜２_Ｎにおける流量がほぼ等しく、１つの測定路２_１における流量がその半分程度しかないような場合、制御回路部９では上記測定路２_１で送受波器３Ａ_１，３Ｂ_１の故障、測定路２_１の変形又は異物の侵入、あるいは送受波器３Ａ_１，３Ｂ_１を送受波器駆動部４と接続する配線の断線などの異常が発生したと判断する。ここで、通常の測定周期（例えば、２秒）よりも充分に短い周期（例えば、０．１秒）で異常検出のための流量測定を行うことにより、時間的要因による流量のばらつきをできるだけ少なくして検出の精度を高めることができる。なお、測定路２が３つ以上（Ｎ≧３）であって他の流量との差がしきい値を越える流量が測定された測定路２が複数ある場合、制御回路部９では多数決によって異常の生じた測定路２を特定する。
【００２２】
而して、本実施形態は上述のように構成したものであり、互いに並列に接続された複数の測定路２_１〜２_Ｎにはほぼ同じ流量の流体が流れることとなるから、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に、何れかの測定路２_ｉで送受波器３Ａ_ｉ，３Ｂ_ｉの故障、測定路２_ｉの変形又は異物の侵入、あるいは送受波器３Ａ_ｉ，３Ｂ_ｉを送受波器駆動部４と接続する配線の断線などの異常が発生していると判断することができる。しかも、このように異常発生を判断する際の流量の測定を通常の測定周期よりも充分に短い周期で行うことで複数の測定路２_１〜２_Ｎの中から異常が発生している測定路を早期に検出することができる。
【００２３】
また、同じ測定路２_ｉについて所定回数以上の異常発生が検出された場合、制御回路部９は異常が検出された測定路２_ｉを特定する番号、異常と判断した時刻、あるいは当該時刻における積算値の少なくとも何れか１つのデータをメモリ部１０に保存するとともに、表示部８で警報表示を行う等の方法により異常の発生を報知し、且つ遮断弁５を閉じるとともに流量の積算値を求める処理を停止することにより、異常発生により積算値の誤差が増大するのを防ぐとともに、異常が発生した測定路の特定や全ての測定路２_１〜２_Ｎにおいて流量が正常に測定されていた期間、あるいはその期間までの積算値等を知ることができるようにしている。
【００２４】
なお、制御回路部９により異常検出を行うタイミングは、（１）予め決められた回数の測定を行ったとき、（２）例えば、２４時間毎というように予め決められた時間毎、（３）例えば、１００回の測定毎に１回というように予め決められた測定回数毎、（４）予め決められた特定の領域の流量が検出されたとき、（５）数回の測定における流量の変動幅が予め決められた基準値を超えたとき、（６）圧力測定部７で測定する流体の圧力の変動幅が予め決められた設定値を超えたとき、のうちの少なくとも何れか一つとすればよい。
【００２５】
（実施形態２）
本実施形態は、図３に示すように第３室２７を第４室２９と仕切る隔壁２８と、この隔壁２８を貫通して第３室２７と第４室２９を連通する第２の測定路１１と、第２の測定路１１を流れる流体の流量が所定の基準値を上回る場合に開放して第２の測定路１１をバイパスする切替弁１２とを備え、一対の送受波器（図示せず）が第２の測定路１１の上流側と下流側に配設された構成を有している。ここで、第２の測定路１１に配設された一対の送受波器は他の送受波器３Ａ_１，３Ｂ_１、…と同様に送受波器駆動部４により駆動される。
【００２６】
而して、本実施形態では、流入口２１から導入される流体の流量が比較的に大きい場合（大流量の場合）に、第１の測定路２において流量を測定し、流入口２１から導入される流体の流量が比較的に小さい場合（小流量の場合）に、切替弁１２を閉塞し第２の測定路１１において流量を測定する。
【００２７】
次に、本実施形態において第１の測定路２又は第２の測定路１１について異常の発生を検出する手順を説明する。制御回路部９は測定周期よりも充分に短い周期（例えば、０．１秒）で第１の測定路２並びに第２の測定路１１の流量の測定を行い、各測定路２，１１における流量の少なくとも何れか一方が第２の測定路１１で測定可能な上限値以下であったとき、すなわち、切替弁１２を閉塞した状態で測定したと考えられる流量を第１の測定路２及び第２の測定路１１のどちらかで測定したとき、第１及び第２の測定路２，１１における流量を比較し、例えば第１の測定路２に対して第２の測定路１１の流量が２倍以上、あるいは第２の測定路１１に対して第１の測定路２の流量が２倍以上、あるいは第１の測定路２と第２の測定路１１の流量の差が１ｍ^３／ｈ以上であった場合に第１又は第２の測定路２，１１の何れか一方に異常が生じていると判断する。
【００２８】
このように大流量用の第１の測定路２と小流量用の第２の測定路１１とを備える構成においても、実施形態１と同様に何れかの測定路２，１１で送受波器の故障、測定路２，１１の変形又は異物の侵入、あるいは送受波器を送受波器駆動部４と接続する配線の断線などの異常が発生していると判断することができる。しかも、このように異常発生を判断する際の流量の測定を通常の測定周期よりも充分に短い周期で行うことで第１及び第２の測定路２，１１の何れかに異常が発生していることを早期に検出することができる。なお、同じ測定路２，１１について所定回数以上の異常発生が検出された場合の処置、並びに制御回路部９により異常検出を行うタイミングについては実施形態１と同様であるから説明は省略する。
【００２９】
（実施形態３）
本実施形態は、図４に示すように実施形態２における第１の測定路２を、実施形態１と同様に互いに並列に接続される複数の測定路２_１〜２_Ｎで構成したものであり、これ以外の構成は実施形態２と共通である。
【００３０】
而して、本実施形態では、流入口２１から導入される流体の流量が比較的に大きい場合（大流量の場合）に、実施形態１と同様の手順でＮ個の測定路２_１〜２_Ｎにおける流量の総和として流量を測定し、流入口２１から導入される流体の流量が比較的に小さい場合（小流量の場合）に、切替弁１２を閉塞し第２の測定路１１において流量を測定する。なお、第２の測定路１２は小さな流量を測定するためのものであるから、例えば、Ｎ個の測定路２_１〜_Ｎと同一形状、同一寸法としてもよい。
【００３１】
次に、本実施形態においてＮ個の測定路２_１〜２_Ｎ又は第２の測定路１１について異常の発生を検出する手順を説明する。制御回路部９は測定周期よりも充分に短い周期（例えば、０．１秒）で測定路２_１〜２_Ｎ並びに第２の測定路１１の流量の測定を行い、実施形態１と同様に各測定路２_１〜２_Ｎ及び第２の測定路１１における流量を比較し、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に当該流量の測定路に上述のような異常が生じていると判断する。例えば、測定路２_１以外の測定路２_２〜２_Ｎ及び第２の測定路１１における流量が全てゼロ（０±１００リットル／ｈ以内、以下同じ）のときに測定路２_１における流量がゼロでないとき、あるいは測定路２_１における流量が測定路２_２〜２_Ｎにおける全ての流量に対して５０％以上多かったとき、制御回路部９は測定路２_１に異常が生じていると判断する。
【００３２】
一方、第１の測定路２を構成する各測定路２_１〜２_Ｎにおける流量を比較し、他の測定路における流量との差が所定の基準値を超える流量が存在しなかった場合には、各測定路２_１〜２_Ｎにおける流量の総和又は第２の測定路１１の流量の何れかが第２の測定路１１で測定できる上限値以下であったとき、すなわち、切替弁１２を閉塞した状態で測定したと考えられる流量を各測定路２_１〜２_Ｎ（総和流量）及び第２の測定路１１の何れか一方が測定したとき、各測定路２_１〜２_Ｎの総和流量と第２の測定路１１における流量を比較し、例えば、各測定路２_１〜２_Ｎの総和流量に対して第２の測定路１１の流量が２倍以上、あるいは各測定路２_１〜２_Ｎの総和流量と第２の測定路１１の流量差が１ｍ^３／ｈ以上であった場合に、制御回路９は第２の測定路１１に異常が生じていると判断する。
【００３３】
このように大流量用のＮ個の測定路２_１〜２_Ｎからなる第１の測定路２と小流量用の第２の測定路１１とを備える構成においても、実施形態１と同様に送受波器３Ａ_ｉ，３Ｂ_ｉの故障、測定路２_ｉ，１１の変形又は異物の侵入、あるいは送受波器３Ａ_ｉ，３Ｂ_ｉを送受波器駆動部４と接続する配線の断線などの異常が発生していると判断することができる。しかも、このように異常発生を判断する際の流量の測定を通常の測定周期よりも充分に短い周期で行うことで複数の測定路２_１〜２_Ｎ，１１の中から異常が発生している測定路を早期に検出することができる。なお、同じ測定路２_１〜２_Ｎ，１１について所定回数以上の異常発生が検出された場合の処置、並びに制御回路部９により異常検出を行うタイミングについては実施形態１と同様であるから説明は省略する。
【００３４】
【発明の効果】
請求項１の発明は、少なくとも断面積が等しく且つ互いに並列に接続される複数の測定路と、各測定路毎に設けられ当該測定路に流れる流体の流速を検出する複数の流速検出手段と、各流速検出手段に所定の測定周期で順番に流速の検出を行わせる制御手段と、各流速検出手段で検出する流速から各々の測定路における流体の流量を求めるとともに各測定路における流量の総和を求めて流体の流量を測定する流量演算手段と、前記測定周期よりも充分に短い周期で各流速検出手段に順番に流速の検出を行わせるとともに流量演算手段により求めた各測定路における流量を比較し、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に当該流量の測定路又は流速検出手段に異常が生じていると判断する異常検出手段とを備えたので、互いに並列に接続された複数の測定路にはほぼ同じ流量の流体が流れることとなるから、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に当該流量の測定路又は流速検出手段に、流速検出手段の故障や測定路の変形又は異物の侵入あるいは流速検出手段を流量演算手段に接続する配線の断線などの異常が発生していると判断することができ、しかも、このように異常発生を判断する際の流量の測定を通常の測定周期よりも充分に短い周期で行うことで複数の測定路の中から異常が発生している測定路を早期に検出することができる。
【００３５】
請求項２の発明は、測定流量域が比較的に大きい第１の測定路と、測定流量域が比較的に小さく且つ第１の測定路と直列に接続される第２の測定路と、第２の測定路を流れる流体の流量が所定の基準値を上回る場合に開放して第２の測定路をバイパスする切替弁と、第１の測定路に流れる流体の流速を検出する第１の流速検出手段と、第２の測定路に流れる流体の流速を検出する第２の流速検出手段と、切替弁が開いているときには第１の流速検出手段に所定の測定周期で流速の検出を行わせるとともに切替弁が閉じているときには第２の流速検出手段に所定の測定周期で流速の検出を行わせる制御手段と、第１及び第２の流速検出手段で検出する流速からそれぞれ第１又は第２の測定路における流体の流量を求める流量演算手段と、前記測定周期よりも充分に短い周期で第１及び第２の流量検出手段に順番に流速の検出を行わせるとともに流量演算手段により求めた第１又は第２の測定路における流量の少なくとも何れか一方が所定の基準値を下回り、且つ第１の測定路における流量と第２の測定路における流量の差が所定のしきい値を越えた場合に第１並びに第２の測定路又は第１並びに第２の流速検出手段の少なくとも何れか一方に異常が生じていると判断する異常検出手段とを備えたので、直列に接続された第１及び第２の測定路には同じ流量の流体が流れることとなるから、第１及び第２の測定路における流量の違いに基づいて、第１又は第２の流速検出手段の故障や第１又は第２の測定路の変形又は異物の侵入あるいは第１又は第２の流速検出手段を流量演算手段に接続する配線の断線などの異常が発生していると判断することができ、しかも、このように異常発生を判断する際の流量の測定を通常の測定周期よりも充分に短い周期で行うことで異常が発生している測定路を早期に検出することができる。
【００３６】
請求項３の発明は、請求項２の発明において、少なくとも断面積が等しい複数の測定路を互いに並列に接続して第１の測定路が構成され、第１の測定路を構成する各測定路毎に設けられる複数の流速検出手段により第１の流速検出手段が構成されてなり、制御手段は、第１の流速検出手段を構成する各流速検出手段に所定の測定周期で順番に流速の検出を行わせ、流量演算手段は、第１の流速検出手段を構成する各流速検出手段で検出する流速から第１の測定路を構成する各々の測定路における流体の流量を求めるとともに各測定路における流量の総和を求めて第１の測定路における流体の流量を測定し、異常検出手段は、前記測定周期よりも充分に短い周期で第１の流速検出手段を構成する各流速検出手段に順番に流速の検出を行わせるとともに流量演算手段により求めた第１の測定路を構成する各測定路における流量を比較し、他の測定路における流量との差が所定のしきい値を越える流量が存在する場合に当該流量の測定路又は第１の流速検出手段を構成する流速検出手段に異常が生じていると判断するので、第１の測定路を構成する互いに並列接続された複数の測定路における流量の総和として大きな流量を測定し、これら複数の測定路からなる第１の測定路に直列に接続された第２の測定路において小さな流量を測定する場合において、第１の測定路を構成する複数の測定路や第２の測定路、あるいは第１の流速検出手段を構成する複数の流速検出手段や第２の流速検出手段に発生する異常を早期に検出することができる。
【００３７】
請求項４の発明は、請求項３の発明において、異常検出手段は、流量演算手段により求めた第１の測定路を構成する各測定路における流量を比較し、他の測定路における流量との差が所定のしきい値を越える流量が存在しない場合に第２の測定路又は第２の流速検出手段に異常が生じていると判断するので、第２の測定路又は第２の流速検出手段に発生する異常を早期に検出することができる。
【００３８】
請求項５の発明は、請求項１又は３又は４の発明において、３つ以上の測定路を備え、異常検出手段は、多数決により異常の生じた測定路を特定するので、請求項１又は３又は４の発明と同様の効果を奏する。
【００３９】
請求項６の発明は、請求項１〜４の何れかの発明において、各測定路への流体の流入を遮断する遮断弁と、データを記憶する記憶手段とを備え、流量演算手段は、測定周期毎の流量の積算値を求める処理を行い、異常検出手段は、同一の測定路について所定回数以上の異常発生を検出した場合に当該測定路を特定する番号、異常と判断した時刻及び当該時刻における積算値の少なくとも何れか１つのデータを記憶手段に記憶するとともに、異常発生の報知、遮断弁の閉止、あるいは流量演算手段による流量の積算値を求める処理の停止のうちの少なくとも何れか１つを実行させるので、異常発生により積算値の誤差が増大するのを防ぐとともに、異常が発生した測定路の特定や全ての測定路において流量が正常に測定されていた期間、あるいはその期間までの積算値等を知ることができる。
【００４０】
請求項７の発明は、請求項１又は２又は３の発明において、異常検出手段は、予め決めた条件が満たされたときに異常検出を行うので、例えば予め決められた測定回数や測定時間、あるいは測定間隔毎に異常検出を行うことができる。
【図面の簡単な説明】
【図１】実施形態１を示すブロック図である。
【図２】同上の概略構成図である。
【図３】実施形態２を示す概略構成図である。
【図４】実施形態３を示す概略構成図である。
【図５】従来例を示すブロック図である。
【符号の説明】
２_１〜２_Ｎ測定路
３Ａ_１〜３Ａ_Ｎ，３Ｂ_１〜３Ｂ_Ｎ送受波器
４送受波器駆動部
８表示部
９制御回路部
１０メモリ部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flow meter for measuring a flow rate of a fluid such as city gas.
[0002]
[Prior art]
Conventionally, as a flow meter used in a gas meter that measures the amount of gas used, the flow velocity of the ultrasonic wave is detected based on the time (propagation time) that the ultrasonic wave propagates through the fluid, and the detected flow velocity is multiplied by the cross-sectional area of the flow path. An ultrasonic flow meter for measuring the flow rate is well known. FIG. 5 is a schematic diagram showing an example of a conventional ultrasonic flow meter (gas meter). This flow meter is disposed on the gas flow path 1 through which gas passes, the measurement path 2 ′ provided in the middle of the gas flow path 1, and the upstream and downstream sides of the measurement path 2 ′ to transmit and receive ultrasonic waves. A pair of transducers 3A and 3B that perform waves, a transducer drive unit 4 that drives the transducers 3A and 3B to transmit and receive ultrasonic waves, and a cutoff provided upstream of the measurement path 2 ' A valve 5, a shut-off valve drive unit 6 that drives the shut-off valve 5, a pressure measurement unit 7 that is provided downstream of the measurement path 2 ′ and measures the pressure of the fluid, and the amount of gas used (integrated flow rate) The display unit 8 to be displayed, the transducer drive unit 4, the shutoff valve drive unit 6, the control circuit unit 9 'for controlling the display unit 8, and various data necessary for the operation of the control circuit unit 9' are stored. And a memory unit 10. Then, when the control circuit unit 9 ′ outputs a drive signal to the transducer drive unit 4 at a predetermined time interval T, the transducer drive unit 4 alternately generates ultrasonic waves from the pair of transducers 3A and 3B. The transmission time t1 of the ultrasonic wave when transmitting the ultrasonic wave from the upstream transducer 3A toward the downstream transducer 3B, and the upstream transmission / reception from the downstream transducer 3B The ultrasonic wave propagation time t2 when the ultrasonic wave is transmitted toward the waver 3A is measured by the control circuit unit 9 ′, and the flow velocity v of the fluid is obtained by the following equation.
[0003]
v = {L / (2 cos θ)} × (1 / t1-1 / t2)
However, L is the distance between the transducers 3A and 3B, and θ is the inclination angle of the transducers 3A and 3B with respect to the central axis of the measurement path 2 ′. The fluid flow rate (instantaneous flow rate) q is obtained by multiplying the flow velocity v thus obtained by the cross-sectional area S of the measurement path 2 ′ (q = v × S [m ³ / H]), and by multiplying the instantaneous flow rate q by the time interval T, the integrated flow rate Q is obtained.
[0004]
Further, the control circuit unit 9 ′ has some abnormality in the use of the gas when the measured flow rate q is larger than the assumed flow rate or when the predetermined flow rate q is measured exceeding a preset duration. When it is determined that the gas has been generated and the supply of gas is stopped by controlling the shut-off valve drive unit 6 to close the shut-off valve 5, or there is no time zone in which the flow rate q is almost zero every 30 days Therefore, it is determined that a leak (gas leak) has occurred in the inner pipe facility downstream of the gas meter, and an alarm is displayed on the display unit 8, or the fluid is measured by the pressure measuring unit 7 at a predetermined interval (for example, every 10 seconds). When the pressure is measured and it is determined that some abnormality has occurred even when the fluid pressure rises or falls abnormally, the shutoff valve drive unit 6 is controlled to close the shutoff valve 5 to supply gas. Has a function to stop.
[0005]
[Problems to be solved by the invention]
By the way, in order to improve the stability of flow measurement, a plurality of measurement paths connected in parallel to each other are provided, and a pair of transducers are provided for each measurement path, and the flow rates in the individual measurement paths are measured in order. Thus, a flow meter is provided in which the sum of these measured values is the total flow rate. As described above, in the flowmeter having a plurality of measurement paths, an abnormality such as a failure of the transducer, a deformation of the measurement path or an intrusion of foreign matter, or a disconnection of the wiring connecting the transducer occurs in any of the measurement paths. In such a case, it is necessary to detect such an abnormality early because the entire flow rate cannot be measured accurately. However, since the measurement of the flow rate in a plurality of measurement paths is sequentially performed at a predetermined measurement cycle, there is a problem that it takes time to specify a measurement path in which an abnormality has occurred.
[0006]
In addition, a first measurement path for measuring a large flow rate, a second measurement path for measuring a small flow rate connected in series to the first measurement path, and a fluid flowing through the second measurement path And a switching valve that opens when the flow rate exceeds a predetermined reference value and bypasses the second measurement path. When the fluid flow rate exceeds the reference value, that is, when the flow rate is large, the switching valve opens. When the second measurement path is bypassed and the flow rate is measured in the first measurement path and the flow rate is lower than the reference value, that is, when the flow rate is small, the switching valve is closed and the flow rate is reduced in the second measurement path. A flow meter adapted to measure is provided. A flow meter is also provided in which the first measurement path is composed of a plurality of measurement paths connected in parallel. As described above, even in a flowmeter having two types of measurement paths for large flow rate and small flow rate, failure of the transducer, deformation of the measurement channel, intrusion of foreign matter, or connection of the transducer is connected in any of the measurement channels. Since the flow rate cannot be accurately measured when an abnormality such as disconnection of the wiring to be generated occurs, it is necessary to detect such an abnormality early.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flowmeter capable of early detection of a measurement path in which an abnormality has occurred from a plurality of measurement paths. .
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the first aspect of the present invention detects a plurality of measurement paths that are at least equal in cross-sectional area and connected in parallel to each other, and detects the flow velocity of the fluid that is provided for each measurement path and flows through the measurement path. A plurality of flow rate detection means, a control means for causing each flow rate detection means to detect a flow rate in order at a predetermined measurement period, and obtaining a flow rate of fluid in each measurement path from the flow rate detected by each flow rate detection means The flow rate calculation means for measuring the flow rate of the fluid by obtaining the sum of the flow rates in each measurement path, and the flow rate calculation means in which each flow rate detection means sequentially detects the flow rate at a cycle sufficiently shorter than the measurement cycle. The flow rate in each measurement path is compared, and if there is a flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined threshold, an abnormality has occurred in the measurement path for the flow rate or the flow velocity detection means. And an abnormality detecting means for judging that the same flow rate of fluid flows in a plurality of measurement paths connected in parallel to each other. If there is a flow rate that exceeds the threshold value, the flow rate measurement means or flow rate detection means may be damaged by the flow rate detection means, the measurement path may be deformed, foreign matter may enter, or the flow rate detection means may be connected to the flow rate calculation means. It is possible to determine that an abnormality such as a disconnection has occurred, and in addition, by measuring the flow rate when determining the occurrence of an abnormality in this way at a cycle sufficiently shorter than the normal measurement cycle, multiple measurement paths It is possible to early detect a measurement path in which an abnormality has occurred.
[0009]
In order to achieve the above object, the invention according to claim 2 has a first measurement path having a relatively large measurement flow rate range, a relatively small measurement flow rate range, and is connected in series with the first measurement path. A second measurement path, a switching valve that opens when the flow rate of the fluid flowing through the second measurement path exceeds a predetermined reference value and bypasses the second measurement path, and a flow of the fluid flowing through the first measurement path The first flow rate detection means for detecting the flow rate, the second flow rate detection means for detecting the flow rate of the fluid flowing in the second measurement path, and the first flow rate detection means when the switching valve is open, perform predetermined measurement. The flow rate is detected at a cycle, and when the switching valve is closed, the second flow rate detection unit detects the flow rate at a predetermined measurement cycle, and the first and second flow rate detection units detect the flow rate. The flow rate of the fluid in the first or second measurement path is obtained from the flow velocity. In the first or second measurement path obtained by the flow rate calculation means and the flow rate calculation means, and the first and second flow rate detection means sequentially detect the flow velocity at a cycle sufficiently shorter than the measurement cycle. First and second measurements when at least one of the flow rates falls below a predetermined reference value and the difference between the flow rate in the first measurement path and the flow rate in the second measurement path exceeds a predetermined threshold value An abnormality detection means for judging that an abnormality has occurred in at least one of the path or the first and second flow velocity detection means, and the first and second measurement paths connected in series Therefore, based on the difference in the flow rates in the first and second measurement paths, the failure of the first or second flow velocity detection means or the first or second measurement path. Deformation or intrusion of foreign matter or first or It is possible to determine that an abnormality such as disconnection of the wiring connecting the flow velocity detecting means 2 to the flow rate calculating means has occurred, and to measure the flow rate when determining the occurrence of the abnormality in this way The measurement path in which an abnormality has occurred can be detected at an early stage by performing the cycle sufficiently shorter than that.
[0010]
According to a third aspect of the present invention, in the second aspect of the invention, a plurality of measurement paths having at least equal cross-sectional areas are connected in parallel to each other to form a first measurement path, and each measurement path constituting the first measurement path A plurality of flow rate detection means provided for each form a first flow rate detection means, and the control means detects the flow rate in order at a predetermined measurement period for each flow rate detection means constituting the first flow rate detection means. The flow rate calculation means obtains the flow rate of the fluid in each measurement path constituting the first measurement path from the flow velocity detected by each flow speed detection means constituting the first flow velocity detection means, and in each measurement path The flow rate of the fluid in the first measurement path is measured by obtaining the sum of the flow rates, and the abnormality detection means sequentially applies to each flow velocity detection means constituting the first flow velocity detection means in a cycle sufficiently shorter than the measurement cycle. When the flow velocity is detected The flow rate in each measurement path constituting the first measurement path obtained by the flow rate calculation means is compared, and if there is a flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined threshold, the flow rate The flow rate in the plurality of measurement paths connected in parallel to each other constituting the first measurement path is characterized in that it is determined that an abnormality has occurred in the measurement path or the flow speed detection means constituting the first flow rate detection means. In the case where a large flow rate is measured as a sum and a small flow rate is measured in a second measurement path connected in series to the first measurement path composed of the plurality of measurement paths, a plurality of the first measurement path is configured. Abnormalities that occur in the measurement path, the second measurement path, or the plurality of flow velocity detection means and the second flow velocity detection means that constitute the first flow velocity detection means can be detected at an early stage.
[0011]
According to a fourth aspect of the present invention, in the third aspect of the invention, the abnormality detection means compares the flow rates in the respective measurement paths constituting the first measurement path obtained by the flow rate calculation means, It is determined that an abnormality has occurred in the second measurement path or the second flow velocity detection means when there is no flow rate at which the difference exceeds a predetermined threshold, and the second measurement path or the second measurement path Abnormalities occurring in the flow velocity detecting means can be detected at an early stage.
[0012]
The invention of claim 5 is characterized in that, in the invention of claim 1, 3 or 4, three or more measurement paths are provided, and the abnormality detection means specifies a measurement path in which an abnormality has occurred by majority decision. The same effect as the invention of 1 or 3 or 4 is exhibited.
[0013]
The invention of claim 6 is the invention according to any one of claims 1 to 4, further comprising a shutoff valve for shutting off the inflow of fluid to each measurement path, and a storage means for storing data, The process for obtaining the integrated value of the flow rate for each cycle is performed, and the abnormality detection means identifies the number for identifying the measurement path when the occurrence of the abnormality more than a predetermined number of times on the same measurement path, the time when the abnormality is determined, and the time Is stored in the storage means, and at least one of the notification of the occurrence of abnormality, the closing of the shut-off valve, or the stop of the process for obtaining the integrated value of the flow rate by the flow rate calculating means. In this period, the error in the integrated value is prevented from increasing due to the occurrence of an abnormality, and the measurement path in which the abnormality has occurred is identified and the flow rate is normally measured in all measurement paths. , Or it is possible to know the integrated value or the like up to the period.
[0014]
The invention of claim 7 is characterized in that, in the invention of claim 1, 2 or 3, the abnormality detecting means performs abnormality detection when a predetermined condition is satisfied. Abnormality detection can be performed at every measurement time or measurement interval.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 is a block diagram showing a flow meter of the present embodiment, and FIG. 2 is a schematic view schematically showing the internal structure of the flow meter. However, the same components as those in the conventional example shown in FIG.
[0016]
As shown in FIG. 2, the flow meter has a housing 20 in which an inlet 21 for fluid (gas) is provided on one end side and an outlet 22 is provided on the other end side. The interior of the housing 20 is partitioned into three chambers (first chamber 25, second chamber 26, and third chamber 27) by partition walls 23, 24. The first chamber 25 communicates with the inflow port 21, and the third chamber 27 communicates with the outlet 22. The partition wall 23 that partitions the first chamber 25 and the second chamber 26 is provided with a shut-off valve 5 so that the movement of fluid from the first chamber 25 to the second chamber 26 can be shut off. Further, a plurality (N) of measurement paths 2 are provided so as to penetrate the partition wall 24 that partitions the second chamber 26 and the third chamber 27. ₁ ~ 2 _N Are arranged side by side, and these multiple measurement paths 2 ₁ ~ 2 _N Are connected in parallel between the second chamber 26 and the third chamber 27. Furthermore, each measurement path 2 ₁ ~ 2 _N Are formed in the same size and shape and are not shown in FIG. ₁ ~ 2 _N A pair of transducers 3A on the upstream side and downstream side of the ₁ , 3B ₁ ... 3A _N , 3B _N Is arranged. Thus, the fluid introduced from the inlet 21 into the first chamber 25 moves to the second chamber 26 via the shut-off valve 5, and N measurement paths 2 ₁ ~ 2 _N Are uniformly moved to the third chamber 27 and led out of the housing 20 from the outlet 22. The third chamber 27 is provided with a pressure measuring unit 7 for monitoring the pressure fluctuation of the fluid.
[0017]
As shown in FIG. 1, the flow meter of the present embodiment includes each measurement path 2. ₁ ~ 2 _N Each pair of transducers 3A provided for each ₁ , 3B ₁ ... 3A _N , 3B _N A transmitter / receiver drive unit 4 for transmitting and receiving ultrasonic waves, a shut-off valve drive unit 6 for driving the shut-off valve 5, a display unit 8 for displaying the measured flow rate (integrated flow rate), and the like A control circuit unit 9 for controlling the wave drive unit 4, the shut-off valve drive unit 6 and the display unit 8, and a memory unit 10 for storing various data necessary for the operation of the control circuit unit 9 are provided. One transducer 3A ₁ ~ 3A _N Is each measurement path 2 ₁ ~ 2 _N The other transmitter / receiver 3B ₁ ~ 3B _N Is each measurement path 2 ₁ ~ 2 _N The transmitter / receiver 3A which is disposed on the downstream side of the transmitter and becomes a pair ₁ ~ 3A _N Opposite. The transducer drive unit 4 is connected to each transducer 3A. ₁ ~ 3A _N , 3B ₁ ~ 3B _N To transmit and receive ultrasonic waves individually, and when the ultrasonic waves transmitted from one transmitter / receiver are received by the other transmitter / receiver in a pair, the fact is notified. A signal (received signal) is output to the control circuit unit 9.
[0018]
The control circuit unit 9 includes a microcomputer as a main component, and outputs a drive signal to the transducer drive unit 4 at a predetermined measurement cycle (for example, 2 seconds), whereby the transducer drive unit 4. Each pair of transducers 3A ₁ , 3B ₁ ... 3A _N , 3B _N The ultrasonic wave is alternately transmitted from the upstream side of the transmitter / receiver 3A. ₁ ~ 3A _N Transmitter / receiver 3B on the downstream side ₁ ~ 3B _N Ultrasonic wave propagation time t1 when an ultrasonic wave is transmitted toward ₁ ~ T1 _N And the downstream transducer 3B ₁ ~ 3B _N Transmitter / receiver 3A upstream from ₁ ~ 3A _N Propagation time t2 when ultrasonic waves are transmitted toward ₁ ~ T2 _N Is measured based on the output timing of the drive signal and the input timing of the received signal from the transducer drive unit 4 to measure the fluid flow rate (instantaneous flow rate) as described in the conventional example. That is, the control circuit unit 9 includes N measurement paths 2. ₁ ~ 2 _N Measure the flow rate at the above measurement cycle in order, and measure all 2 ₁ ~ 2 _N The total flow rate is calculated by calculating the total flow rate, the total flow rate is measured at a predetermined time interval, and the total flow rate is multiplied by the time interval to obtain the integrated flow rate. It also serves as a calculation means.
[0019]
The display unit 8 includes a display device such as an LED (light emitting diode) or an LCD (liquid crystal display), and drives the display device based on a signal output from the control circuit unit 9 to thereby determine the value of the integrated flow rate, which will be described later. Various displays such as an alarm display are performed. Further, the memory unit 10 serving as a storage means is composed of a rewritable nonvolatile memory such as an EEPROM, and the measurement cycle and the measurement path 2 are described above. ₁ ~ 2 _N In addition to the setting data such as the cross-sectional area, various data when an abnormality occurs are stored as will be described later.
[0020]
By the way, a plurality of measurement paths 2 are thus obtained. ₁ ~ 2 _N In the case of a configuration that measures the flow rate individually, either measurement path 2 _i The transducer 3A _i , 3B _i Failure, measuring path 2 _i Deformation or intrusion of foreign matter, or transducer 3A _i , 3B _i If an abnormality such as disconnection of the wiring connecting the transmitter / receiver drive unit 4 occurs, the entire flow rate cannot be measured accurately, and if the measurement is overlooked and the measurement is continued, The error of the integrated flow rate is accumulated with time.
[0021]
Therefore, in the present embodiment, the control circuit unit 9 has a measurement path 2 with a cycle sufficiently shorter than the measurement cycle (for example, 0.1 second). ₁ ~ 2 _N Each flow path is measured and each measurement path 2 ₁ ~ 2 _N When there is a flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined threshold value, it is determined that the above-described abnormality has occurred in the measurement path for the flow rate. Therefore, the control circuit unit 9 constitutes an abnormality detection means. For example, measurement path 2 ₂ ~ 2 _N The flow rates at are almost equal, one measurement path 2 ₁ In the case where the flow rate is only about half of that, the control circuit unit 9 uses the measurement path 2 described above. ₁ The transducer 3A ₁ , 3B ₁ Failure, measuring path 2 ₁ Deformation or intrusion of foreign matter, or transducer 3A ₁ , 3B ₁ It is determined that an abnormality such as disconnection of the wiring connected to the transducer drive unit 4 has occurred. Here, by performing flow rate measurement for abnormality detection at a sufficiently shorter cycle (for example, 0.1 second) than a normal measurement cycle (for example, 2 seconds), the variation in flow rate due to time factors is minimized. Thus, the detection accuracy can be increased. In addition, when there are a plurality of measurement paths 2 in which there are three or more measurement paths 2 (N ≧ 3) and a flow rate at which the difference from other flow rates exceeds a threshold value, the control circuit unit 9 is abnormal due to a majority decision. The measurement path 2 in which the error occurred is specified.
[0022]
Thus, the present embodiment is configured as described above, and a plurality of measurement paths 2 connected in parallel to each other. ₁ ~ 2 _N Therefore, when there is a flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined threshold value, any one of the measurement paths 2 _i The transducer 3A _i , 3B _i Failure, measuring path 2 _i Deformation or intrusion of foreign matter, or transducer 3A _i , 3B _i It can be determined that an abnormality such as disconnection of the wiring connected to the transducer drive unit 4 has occurred. In addition, a plurality of measurement paths 2 can be obtained by measuring the flow rate when determining the occurrence of an abnormality in this manner at a cycle sufficiently shorter than the normal measurement cycle. ₁ ~ 2 _N It is possible to early detect a measurement path in which an abnormality has occurred.
[0023]
The same measurement path 2 _i When the occurrence of abnormality more than a predetermined number of times is detected, the control circuit unit 9 detects the measurement path 2 where the abnormality is detected _i The number that identifies the error, the time at which it was determined that there was an abnormality, or at least one of the accumulated value at that time is stored in the memory unit 10 and the occurrence of an abnormality is reported by a method such as displaying an alarm on the display unit 8 In addition, by closing the shutoff valve 5 and stopping the process for obtaining the integrated value of the flow rate, it is possible to prevent the error of the integrated value from increasing due to the occurrence of an abnormality, and to identify the measurement path in which the abnormality has occurred and all the measurement paths 2 ₁ ~ 2 _N It is possible to know the period during which the flow rate was normally measured or the integrated value up to that period.
[0024]
The timing for detecting the abnormality by the control circuit unit 9 is (1) when a predetermined number of times of measurement is performed, (2) every predetermined time, for example, every 24 hours, (3) For example, once every predetermined number of measurements, such as once every 100 measurements, (4) when a flow rate in a specific area is detected, (5) fluctuations in flow rate in several measurements When the width exceeds a predetermined reference value, (6) When the fluctuation range of the pressure of the fluid measured by the pressure measuring unit 7 exceeds a predetermined set value, it is at least one of them. That's fine.
[0025]
(Embodiment 2)
In this embodiment, as shown in FIG. 3, a partition wall 28 that partitions the third chamber 27 from the fourth chamber 29, and a second measurement path that passes through the partition wall 28 and communicates the third chamber 27 and the fourth chamber 29. 11 and a switching valve 12 that opens and bypasses the second measurement path 11 when the flow rate of the fluid flowing through the second measurement path 11 exceeds a predetermined reference value, and a pair of transducers (not shown) 2) is arranged on the upstream side and the downstream side of the second measurement path 11. Here, the pair of transducers arranged in the second measurement path 11 is the other transducer 3A. ₁ , 3B ₁ ,... Are driven by the transducer driver 4.
[0026]
Thus, in this embodiment, when the flow rate of the fluid introduced from the inlet 21 is relatively large (in the case of a large flow rate), the flow rate is measured in the first measurement path 2 and introduced from the inlet 21. When the flow rate of the fluid to be applied is relatively small (small flow rate), the switching valve 12 is closed and the flow rate is measured in the second measurement path 11.
[0027]
Next, a procedure for detecting the occurrence of an abnormality in the first measurement path 2 or the second measurement path 11 in the present embodiment will be described. The control circuit unit 9 measures the flow rates of the first measurement path 2 and the second measurement path 11 in a cycle sufficiently shorter than the measurement cycle (for example, 0.1 second), and the flow rates in the measurement channels 2 and 11. When the flow rate is considered to be measured when at least one of these is less than or equal to the upper limit measurable by the second measurement path 11, that is, with the switching valve 12 closed, the first measurement path 2 and the second flow rate are measured. When the flow rate is measured in one of the measurement paths 11, the flow rates in the first and second measurement paths 2 and 11 are compared. The flow rate of the first measurement path 2 is more than twice that of the second measurement path 11 or the difference between the flow rates of the first measurement path 2 and the second measurement path 11 is 1 m. ³ / H or more, it is determined that an abnormality has occurred in one of the first or second measurement paths 2 and 11.
[0028]
In the configuration including the first measurement path 2 for large flow rate and the second measurement path 11 for small flow rate as described above, the transducer is connected to any of the measurement paths 2 and 11 as in the first embodiment. It can be determined that an abnormality such as a failure, deformation of the measurement paths 2 and 11, intrusion of foreign matter, or disconnection of wiring connecting the transducer to the transducer drive unit 4 has occurred. In addition, by measuring the flow rate when determining the occurrence of an abnormality in this manner at a period sufficiently shorter than the normal measurement period, an abnormality occurs in one of the first and second measurement paths 2 and 11. It can be detected early. Note that the processing when an abnormality occurrence is detected a predetermined number of times or more on the same measurement paths 2 and 11 and the timing at which abnormality detection is performed by the control circuit unit 9 are the same as in the first embodiment, and thus the description thereof is omitted.
[0029]
(Embodiment 3)
In the present embodiment, as shown in FIG. 4, the first measurement path 2 in the second embodiment is connected to the plurality of measurement paths 2 in parallel as in the first embodiment. ₁ ~ 2 _N The other configurations are the same as those in the second embodiment.
[0030]
Thus, in the present embodiment, when the flow rate of the fluid introduced from the inlet 21 is relatively large (in the case of a large flow rate), N measurement paths 2 are processed in the same procedure as in the first embodiment. ₁ ~ 2 _N When the flow rate of the fluid introduced from the inlet 21 is relatively small (in the case of a small flow rate), the switching valve 12 is closed and the flow rate is measured in the second measurement path 11. To do. Since the second measurement path 12 is for measuring a small flow rate, for example, N measurement paths 2 ₁ ~ _N The same shape and dimensions may be used.
[0031]
Next, in this embodiment, N measurement paths 2 ₁ ~ 2 _N Or the procedure which detects generation | occurrence | production of abnormality about the 2nd measurement path 11 is demonstrated. The control circuit unit 9 has a measurement path 2 with a period sufficiently shorter than the measurement period (for example, 0.1 second). ₁ ~ 2 _N In addition, the flow rate of the second measurement path 11 is measured, and each measurement path 2 is measured as in the first embodiment. ₁ ~ 2 _N The flow rate in the second measurement path 11 is compared, and if there is a flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined threshold, the above-described abnormality occurs in the measurement path for the flow rate. Judge that For example, measurement path 2 ₁ Measurement path 2 other than ₂ ~ 2 _N When the flow rates in the second measurement path 11 are all zero (within 0 ± 100 liter / h, the same applies hereinafter), the measurement path 2 ₁ When the flow rate at is not zero, or measurement path 2 ₁ The flow rate at is measuring path 2 ₂ ~ 2 _N When the flow rate is 50% or more with respect to all the flow rates in the control circuit section 9, the control circuit section 9 ₁ It is determined that an abnormality has occurred.
[0032]
On the other hand, each measurement path 2 constituting the first measurement path 2 ₁ ~ 2 _N When there is no flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined reference value, each measurement path 2 ₁ ~ 2 _N The flow rate considered to be measured when either the sum of the flow rates at the flow rate or the flow rate of the second measurement path 11 is less than or equal to the upper limit value that can be measured by the second measurement path 11, that is, with the switching valve 12 closed. For each measurement path 2 ₁ ~ 2 _N When one of the (total flow rate) and the second measurement path 11 is measured, each measurement path 2 ₁ ~ 2 _N Are compared with the flow rate in the second measurement path 11, for example, each measurement path 2 ₁ ~ 2 _N The flow rate of the second measurement path 11 is more than twice the total flow rate of each, or each measurement path 2 ₁ ~ 2 _N The difference between the total flow rate and the second measurement path 11 is 1 m. ³ If it is / h or more, the control circuit 9 determines that an abnormality has occurred in the second measurement path 11.
[0033]
In this way, N measuring paths 2 for large flow rate ₁ ~ 2 _N Even in the configuration including the first measurement path 2 and the second measurement path 11 for small flow rate, the transmitter / receiver 3A is the same as in the first embodiment. _i , 3B _i Failure, measuring path 2 _i , 11 or foreign material intrusion, or transducer 3A _i , 3B _i It can be determined that an abnormality such as disconnection of the wiring connected to the transducer drive unit 4 has occurred. In addition, a plurality of measurement paths 2 can be obtained by measuring the flow rate when determining the occurrence of an abnormality in this manner at a cycle sufficiently shorter than the normal measurement cycle. ₁ ~ 2 _N , 11 can be detected at an early stage where the abnormality has occurred. Same measurement path 2 ₁ ~ 2 _N , 11 are the same as those in the first embodiment with respect to the treatment when the occurrence of an abnormality more than a predetermined number of times is detected and the timing at which the control circuit unit 9 detects the abnormality.
[0034]
【The invention's effect】
The invention of claim 1 has a plurality of measurement paths that are at least equal in cross-sectional area and connected in parallel to each other, and a plurality of flow velocity detection means that are provided for each measurement path and detect the flow velocity of the fluid flowing through the measurement paths, Control means for causing each flow velocity detection means to detect the flow velocity in order at a predetermined measurement cycle, and obtaining the flow rate of the fluid in each measurement path from the flow velocity detected by each flow velocity detection means and calculating the sum of the flow rates in each measurement path Compare the flow rate in each measurement path obtained by the flow rate calculation means and the flow rate calculation means for measuring the flow rate of the fluid, and let each flow rate detection means detect the flow rate in order in a cycle sufficiently shorter than the measurement cycle. An abnormality detection means for determining that an abnormality has occurred in the measurement path of the flow rate or the flow velocity detection means when there is a flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined threshold value; Since the same flow rate of fluid flows through multiple measurement paths connected in parallel to each other, there is a flow rate where the difference from the flow rate in other measurement paths exceeds a predetermined threshold. In addition, it is determined that an abnormality has occurred in the flow rate measurement means or flow rate detection means, such as a failure of the flow rate detection means, deformation of the measurement path, intrusion of foreign matter, or disconnection of the wiring connecting the flow rate detection means to the flow rate calculation means. In addition, a measurement path in which an abnormality has occurred from a plurality of measurement paths by measuring the flow rate when judging the occurrence of an abnormality in this manner at a period sufficiently shorter than the normal measurement period. Can be detected early.
[0035]
The invention according to claim 2 includes a first measurement path having a relatively large measurement flow area, a second measurement path having a relatively small measurement flow area and connected in series with the first measurement path, A switching valve that opens when the flow rate of the fluid flowing through the second measurement path exceeds a predetermined reference value and bypasses the second measurement path, and a first flow velocity that detects the flow speed of the fluid flowing through the first measurement path Detection means, second flow velocity detection means for detecting the flow velocity of the fluid flowing through the second measurement path, and causing the first flow velocity detection means to detect the flow velocity at a predetermined measurement period when the switching valve is open. At the same time, when the switching valve is closed, the control unit causes the second flow rate detection unit to detect the flow rate at a predetermined measurement cycle, and the first and second flow rates are detected from the flow rates detected by the first and second flow rate detection units, respectively. A flow rate calculation means for obtaining a flow rate of fluid in the measurement path; The first and second flow rate detection means sequentially detect the flow velocity in a cycle sufficiently shorter than the cycle, and at least one of the flow rates in the first or second measurement path obtained by the flow rate calculation unit is predetermined. When the difference between the flow rate in the first measurement path and the flow rate in the second measurement path exceeds a predetermined threshold value, the first and second measurement paths or the first and second Since at least one of the flow velocity detection means is provided with an abnormality detection means for determining that an abnormality has occurred, fluids having the same flow rate flow through the first and second measurement paths connected in series. From the first and second measurement paths, the first or second flow velocity detecting means is broken, the first or second measurement path is deformed, the foreign object enters, or the first or second. Connect the flow velocity detection means to the flow rate calculation means. It is possible to determine that an abnormality such as disconnection of the wiring to be performed has occurred, and in addition, the flow rate when determining the occurrence of the abnormality is measured at a cycle sufficiently shorter than the normal measurement cycle. It is possible to detect the measurement path in which the error occurs at an early stage.
[0036]
According to a third aspect of the present invention, in the second aspect of the invention, a plurality of measurement paths having at least equal cross-sectional areas are connected in parallel to each other to form a first measurement path, and each measurement path constituting the first measurement path A plurality of flow rate detection means provided for each form a first flow rate detection means, and the control means detects the flow rate in order at a predetermined measurement period for each flow rate detection means constituting the first flow rate detection means. The flow rate calculation means obtains the flow rate of the fluid in each measurement path constituting the first measurement path from the flow velocity detected by each flow speed detection means constituting the first flow velocity detection means, and in each measurement path The flow rate of the fluid in the first measurement path is measured by obtaining the sum of the flow rates, and the abnormality detection means sequentially applies to each flow velocity detection means constituting the first flow velocity detection means in a cycle sufficiently shorter than the measurement cycle. When the flow velocity is detected The flow rate in each measurement path constituting the first measurement path obtained by the flow rate calculation means is compared, and if there is a flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined threshold, the flow rate Therefore, it is determined that an abnormality has occurred in the flow rate detection means constituting the first measurement flow path or the first flow velocity detection means, so that the sum of the flow rates in the plurality of measurement paths connected in parallel constituting the first measurement path is large. When measuring a flow rate and measuring a small flow rate in a second measurement path connected in series to the first measurement path composed of the plurality of measurement paths, a plurality of measurement paths constituting the first measurement path, Abnormalities occurring in the second measurement path or the plurality of flow velocity detecting means and the second flow velocity detecting means constituting the first flow velocity detecting means can be detected at an early stage.
[0037]
According to a fourth aspect of the present invention, in the third aspect of the invention, the abnormality detection means compares the flow rates in the respective measurement paths constituting the first measurement path obtained by the flow rate calculation means, and compares the flow rates in the other measurement paths with each other. Since it is determined that an abnormality has occurred in the second measurement path or the second flow velocity detection means when there is no flow rate whose difference exceeds a predetermined threshold value, the second measurement path or the second flow velocity detection means. Can be detected at an early stage.
[0038]
The invention of claim 5 is the invention of claim 1, 3 or 4, and comprises three or more measurement paths, and the abnormality detection means identifies the measurement path in which an abnormality has occurred by majority decision. Alternatively, the same effects as in the invention of 4 can be obtained.
[0039]
The invention of claim 6 is the invention according to any one of claims 1 to 4, further comprising a shutoff valve for shutting off the inflow of fluid to each measurement path, and a storage means for storing data, The process for obtaining the integrated value of the flow rate for each cycle is performed, and the abnormality detection means identifies the number for identifying the measurement path when the occurrence of the abnormality more than a predetermined number of times on the same measurement path, the time when the abnormality is determined, and the time Is stored in the storage means, and at least one of the notification of the occurrence of abnormality, the closing of the shut-off valve, or the stop of the process for obtaining the integrated value of the flow rate by the flow rate calculating means. Therefore, it is possible to prevent the error of the integrated value from increasing due to the occurrence of an abnormality, and to identify the measurement path where the abnormality has occurred or the period during which the flow rate was normally measured in all the measurement paths. It is possible to know the cumulative values and the like up to that period.
[0040]
The invention of claim 7 is the invention of claim 1, 2 or 3, wherein the abnormality detection means detects abnormality when a predetermined condition is satisfied. Alternatively, abnormality detection can be performed at every measurement interval.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment.
FIG. 2 is a schematic configuration diagram of the above.
FIG. 3 is a schematic configuration diagram showing a second embodiment.
FIG. 4 is a schematic configuration diagram showing a third embodiment.
FIG. 5 is a block diagram showing a conventional example.
[Explanation of symbols]
2 ₁ ~ 2 _N Measuring path
3A ₁ ~ 3A _N , 3B ₁ ~ 3B _N Transducer
4 Transmitter / receiver drive
8 Display section
9 Control circuit
10 Memory part

Claims

A plurality of measurement paths that are at least equal in cross-sectional area and connected in parallel to each other, a plurality of flow speed detection means that are provided for each measurement path and that detect the flow velocity of the fluid flowing through the measurement paths, Measures the flow rate of the fluid by calculating the flow rate of the fluid in each measurement path from the flow rate detected by each flow rate detection means and the control means that detects the flow rate in order at the measurement cycle. The flow rate calculation means and the flow rate detection means in order to detect the flow rate in a cycle sufficiently shorter than the measurement cycle, and compare the flow rate in each measurement path obtained by the flow rate calculation means, in other measurement paths An abnormality detecting means for judging that an abnormality has occurred in the flow rate measuring means or the flow velocity detecting means when there is a flow rate whose difference from the flow rate exceeds a predetermined threshold value. Flowmeter for.

A first measurement path having a relatively large measurement flow area, a second measurement path having a relatively small measurement flow area and connected in series with the first measurement path, and a fluid flowing through the second measurement path A switching valve that opens when the flow rate of the fluid exceeds a predetermined reference value and bypasses the second measurement path, a first flow rate detection means that detects a flow rate of the fluid flowing through the first measurement path, and a second Second flow rate detection means for detecting the flow rate of the fluid flowing in the measurement path, and when the switching valve is open, the first flow rate detection means detects the flow rate at a predetermined measurement period and the switching valve is closed. Sometimes the flow rate of the fluid in the first or second measurement path from the control unit that causes the second flow rate detection unit to detect the flow rate at a predetermined measurement cycle and the flow rate detected by the first and second flow rate detection units, respectively. A flow rate calculation means for obtaining the The first and second flow rate detection means sequentially detect the flow velocity at a high cycle, and at least one of the flow rates in the first or second measurement path obtained by the flow rate calculation means falls below a predetermined reference value. And when the difference between the flow rate in the first measurement path and the flow rate in the second measurement path exceeds a predetermined threshold value, at least one of the first and second measurement paths or the first and second flow velocity detection means. A flow meter comprising: an abnormality detection means for determining that an abnormality has occurred in any one of the two.

A plurality of measurement paths having at least the same cross-sectional area are connected in parallel to each other to form a first measurement path, and the first flow velocity is detected by a plurality of flow velocity detection means provided for each measurement path constituting the first measurement path. The detection means is configured, and the control means causes each of the flow velocity detection means constituting the first flow velocity detection means to detect the flow velocity in order at a predetermined measurement period, and the flow rate calculation means performs the first flow velocity detection. The flow rate of the fluid in each measurement path constituting the first measurement path is obtained from the flow velocity detected by each flow velocity detection means constituting the means, and the sum of the flow rates in each measurement path is obtained to determine the fluid flow rate in the first measurement path. The flow rate is measured, and the abnormality detection unit causes each flow rate detection unit constituting the first flow rate detection unit to sequentially detect the flow rate at a cycle sufficiently shorter than the measurement cycle and obtains the flow rate calculation unit. 1 measuring path The flow rate constituting the measurement path of the flow rate or the first flow velocity detection means when the flow rate in each measurement path is compared and there is a flow rate whose difference from the flow rate in the other measurement path exceeds a predetermined threshold. 3. The flowmeter according to claim 2, wherein it is determined that an abnormality has occurred in the detection means.

The abnormality detection means compares the flow rates in the respective measurement paths constituting the first measurement path determined by the flow rate calculation means, and there is no flow rate whose difference from the flow rates in the other measurement paths exceeds a predetermined threshold value. The flowmeter according to claim 3, wherein it is determined that an abnormality has occurred in the second measurement path or the second flow velocity detection means.

5. The flowmeter according to claim 1, further comprising three or more measurement paths, wherein the abnormality detection means identifies a measurement path in which an abnormality has occurred by majority vote.

Provided with a shut-off valve that shuts off the inflow of fluid to each measurement path and a storage means for storing data, the flow rate calculation means performs a process for obtaining an integrated value of the flow rate for each measurement cycle, and the abnormality detection means is the same When the occurrence of an abnormality more than a predetermined number of times is detected for the measurement path, at least one of the number identifying the measurement path, the time determined to be abnormal, and the integrated value at the time are stored in the storage means, 5. At least any one of generation | occurrence | production notification, closing of a shut-off valve, or the stop of the process which calculates | requires the integrated value of the flow volume by a flow volume calculating means is performed. Flowmeter.

The flowmeter according to claim 1, 2 or 3, wherein the abnormality detection means performs abnormality detection when a predetermined condition is satisfied.