JP5556034B2

JP5556034B2 - Flow velocity or flow rate measuring device

Info

Publication number: JP5556034B2
Application number: JP2009069484A
Authority: JP
Inventors: 文一芝; 晃一竹村; 裕治中林
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2009-03-23
Filing date: 2009-03-23
Publication date: 2014-07-23
Anticipated expiration: 2029-03-23
Also published as: JP2010223659A

Description

本発明は、振動子などを用い、超音波を利用して気体や液体などの流量を計測する流速または流量計測装置に関する。 The present invention relates to a flow velocity or flow rate measuring device that uses a vibrator or the like and measures a flow rate of gas or liquid using ultrasonic waves.

従来の流体の流れ計測装置を図１０を参照して説明すると、流体が流れる流路１０１の上流側と下流側とに一対の超音波振動子１０２，１０３が配置されており、超音波が流体を斜めに横切るようにしてある（例えば、特許文献１参照）。 A conventional fluid flow measuring device will be described with reference to FIG. 10. A pair of ultrasonic transducers 102 and 103 are arranged on the upstream side and the downstream side of a flow path 101 through which a fluid flows, and the ultrasonic waves are fluidized. (See, for example, Patent Document 1).

そして、前記一対の超音波振動子１０２，１０３間を伝搬する超音波の伝搬時間から流体の流速を計測し、これにもとづき流量を演算していた。例えば、時間差から流速を求め、管路の大きさや流れの状態を考慮して流量値を計算できる。 Then, the flow velocity of the fluid is measured from the propagation time of the ultrasonic wave propagating between the pair of ultrasonic transducers 102 and 103, and the flow rate is calculated based on this. For example, the flow rate value can be calculated in consideration of the size of the pipeline and the flow state by obtaining the flow velocity from the time difference.

なお、図中の実線矢印１０４は流体の流れる方向を示し、破線矢印１０５は超音波の伝搬する方向を示している。流体の流れる方向と、超音波の伝搬する方向とは角θで交叉している（例えば、特許文献１参照）。
特開２００２−１３９５８号公報 In addition, the solid line arrow 104 in a figure shows the direction through which a fluid flows, and the broken line arrow 105 has shown the direction through which an ultrasonic wave propagates. The direction in which the fluid flows and the direction in which the ultrasonic waves propagate intersect at an angle θ (for example, see Patent Document 1).
JP 2002-13958 A

しかしながら、前記従来の計測装置では、上流側の超音波振動子１０２から下流側の超音波振動子１０３へ超音波を伝播させ、超音波の伝搬時間Ｔｕｄを、また下流側の超音波振動子１０３から上流側の超音波振動子１０２へ超音波を伝播させ、超音波の伝搬時間Ｔｄｕを交互に計測し、計測した超音波の伝播時間Ｔｕｄ、Ｔｄｕなどを用いて時間差を求め流量を演算していた。そして受信波が一定の振幅になるようオートゲイン増幅器で振幅を調整している。 However, in the conventional measuring apparatus, an ultrasonic wave is propagated from the upstream ultrasonic transducer 102 to the downstream ultrasonic transducer 103, and the ultrasonic propagation time Tud is determined. The ultrasonic wave is propagated from the ultrasonic wave to the ultrasonic transducer 102 on the upstream side, the ultrasonic wave propagation time Tdu is measured alternately, and the flow rate is calculated by calculating the time difference using the measured ultrasonic wave propagation times Tud and Tdu. It was. The amplitude is adjusted by an auto gain amplifier so that the received wave has a constant amplitude.

この際、所定の振幅が得られる受信波形の部分に参照レベルを設定してトリガーレベルとし、伝播時間を計測していた。したがって、トリガ−レベルよりも前の零クロス点を用いて超音波の伝搬時間を計測することができなかった。また、トリガレベル設定、判定の回路を必要としていた。 At this time, a reference level is set to a received waveform portion where a predetermined amplitude can be obtained as a trigger level, and a propagation time is measured. Therefore, the propagation time of the ultrasonic wave cannot be measured using the zero cross point before the trigger level. In addition, a trigger level setting / determination circuit is required.

このため、超音波の到達時間に不確かな時間が含まれることになり、誤差となる場合があり、高精度な流れ計測を実現することができないという課題を有していた。 For this reason, an uncertain time is included in the arrival time of the ultrasonic wave, which may cause an error, and there is a problem that high-precision flow measurement cannot be realized.

即ち、超音波の受信波形は、一般に駆動回路で駆動される周波数で立上がり、順次、超音波変換器固有の振動周波数に変化する。 That is, the ultrasonic reception waveform generally rises at a frequency driven by a drive circuit, and sequentially changes to a vibration frequency unique to the ultrasonic transducer.

あるいは、流路の側壁などからの反射波の影響を受けるなどするため、超音波の受信波形は受信点に近い立上がり部分は周波数が安定しているが、トリガ−レベルを設定するような比較的受信振幅の大きい部分では、上流側と下流側とで受信する波形に差が発生し、伝播時間の誤差として検知されることになる。 Alternatively, since the reception waveform of the ultrasonic wave is affected by the reflected wave from the side wall of the flow path or the like, the frequency at the rising portion near the reception point is stable, but the trigger level is relatively high. In the portion where the reception amplitude is large, a difference occurs in the waveform received between the upstream side and the downstream side, which is detected as an error in propagation time.

また、流路１０１の側壁などで反射した超音波が受信波に若干遅れて到達し、受信波として受信されるので、受信波形がオフセット分を差し引いた場合にゼロ点を通過する零クロス点が不確かになることもあった。 In addition, since the ultrasonic wave reflected by the side wall of the channel 101 arrives at the received wave with a slight delay and is received as the received wave, a zero cross point that passes through the zero point when the received waveform is subtracted from the offset is obtained. Sometimes it was uncertain.

また、トリガレベルを設定する回路が余分に必要という課題も有していた。 In addition, there is a problem that an extra circuit for setting the trigger level is necessary.

本発明は、前記従来の課題を解決するもので、受信した超音波の零クロス点の到達時間を計測し、順次更新することにより、トリガ−レベルの回路を無くし、超音波の到達時間を計測することができるようにして超音波の伝播時間に含まれる誤差を少なくし、高精度な計測を実現しつつ、省電力動作を実現し、さらにトリガレベルを無くしても計測できる回路の簡素化を実現することを目的としている。 The present invention solves the above-mentioned conventional problems, and measures the arrival time of the received ultrasonic zero cross point and sequentially updates it, thereby eliminating the trigger-level circuit and measuring the arrival time of the ultrasonic wave. It is possible to reduce the error included in the propagation time of ultrasonic waves, realize high-accuracy measurement, realize power saving operation, and simplify the circuit that can measure even without trigger level It is intended to be realized.

前記従来の課題を解決するために、本発明の流速または流量計測装置は、被測定流体の流れる流路に配置され超音波を送受信する一対の振動子と、一方の振動子を駆動する送信手段と、他方の受信側振動子の出力信号を電気信号に変換する受信手段と、受信手段の信号の最大値を検出して信号を出す受信波最大値判定手段と、受信手段の信号が予め定めた範囲になると信号を出す受信点検知手段と、前記受信点検知手段の出力を記憶する受信点記憶手段と、前記受信点記憶手段の信号を用いて振動子間を伝搬した超音波信号の伝搬時間を計時する計時手段と、前記計時手段の計時差に基づいて流量を算出する流量演算手段と、前記送信手段と前記受信手段と前記受信波最大値検知手段と受信点検知手段と前記受信点記憶手段と前記計時手段と前記流量演算手段との少なくとも１つを制御する制御手段とを備え、前記受信点記憶手段は前記受信波最大値判定手段の出力信号があるまで上書き
更新するようにしたものである。 In order to solve the above-described conventional problems, the flow velocity or flow rate measuring device according to the present invention includes a pair of transducers that are arranged in a flow path through which a fluid to be measured flows and that transmits and receives ultrasonic waves, and a transmission unit that drives one transducer. A receiving means for converting the output signal of the other receiving-side transducer into an electric signal, a received wave maximum value judging means for detecting a maximum value of the signal of the receiving means and outputting a signal, and a signal of the receiving means are predetermined. A reception point detection means for outputting a signal when it falls within the range, a reception point storage means for storing the output of the reception point detection means, and a propagation of an ultrasonic signal propagated between the transducers using a signal of the reception point storage means Time measuring means for measuring time, flow rate calculating means for calculating a flow rate based on a time difference of the time measuring means, the transmitting means, the receiving means, the received wave maximum value detecting means, the receiving point detecting means, and the receiving point A storage means and the timing means; Serial and control means for controlling at least one of the flow rate calculating unit, said reception point storage means is obtained so as to overwrite update until an output signal of the reception wave maximum value determination unit.

この構成により、上流側の超音波振動子と下流側の超音波振動子間を伝播する超音波の伝播時間、即ち、超音波の到達時間を受信波の振幅最大値よりも前で計測することができる。このため、回路を簡素化し計測した超音波の伝搬時間あるいは到達時間に含まれる誤差を小さくすることができ、高精度な流れ計測を実現しつつ、省電力動作を実現できる。 With this configuration, the propagation time of the ultrasonic wave propagating between the upstream ultrasonic transducer and the downstream ultrasonic transducer, that is, the arrival time of the ultrasonic wave is measured before the maximum amplitude of the received wave. Can do. For this reason, the error included in the propagation time or arrival time of the ultrasonic waves measured by simplifying the circuit can be reduced, and power saving operation can be realized while realizing highly accurate flow measurement.

本発明の、流速または流量計測装置は、受信波の振幅最大値よりも前の零クロス点を用いて超音波の伝搬時間あるいは超音波の到達時間を計測することができるので、超音波の伝搬時間あるいは到達時間に含まれる誤差を小さくすることができ、高精度な流れ計測を実現しつつ、さらにトリガレベルを設定する回路を省略して省電力動作を実現できる。 The flow velocity or flow rate measuring device of the present invention can measure the propagation time of ultrasonic waves or the arrival time of ultrasonic waves using the zero cross point before the maximum amplitude value of the received wave. The error included in the time or the arrival time can be reduced, and the power saving operation can be realized by omitting the circuit for setting the trigger level while realizing highly accurate flow measurement.

第１の発明は被測定流体の流れる流路に配置され超音波を送受信する一対の振動子と、一方の振動子を駆動する送信手段と、他方の受信側振動子の出力信号を電気信号に変換する受信手段と、受信手段の信号の最大値を検出して信号を出す受信波最大値判定手段と、受信手段の信号が予め定めた範囲になると信号を出す受信点検知手段と、前記受信点検知手段の出力を記憶する受信点記憶手段と、前記受信点記憶手段の信号を用いて振動子間を伝搬した超音波信号の伝搬時間を計時する計時手段と、前記計時手段の計時差に基づいて流量を算出する流量演算手段と、前記送信手段と前記受信手段と前記受信波最大値検知手段と受信点検知手段と前記受信点記憶手段と前記計時手段と前記流量演算手段との少なくとも１つを制御する制御手段とを備え、前記受信点記憶手段は前記受信波最大値判定手段の出力信号があるまで上書き更新するものである。 In the first invention, a pair of transducers arranged in a flow path through which a fluid to be measured flows and transmits / receives ultrasonic waves, transmission means for driving one transducer, and an output signal of the other receiving transducer as an electrical signal A receiving means for converting; a received wave maximum value judging means for detecting a maximum value of a signal of the receiving means and outputting a signal; a receiving point detecting means for outputting a signal when the signal of the receiving means falls within a predetermined range; and A reception point storage means for storing the output of the point detection means, a time measurement means for measuring the propagation time of the ultrasonic signal propagated between the transducers using the signal of the reception point storage means, and a time difference between the time measurement means At least one of a flow rate calculation means for calculating a flow rate based on the transmission means, the reception means, the received wave maximum value detection means, a reception point detection means, the reception point storage means, the timing means, and the flow rate calculation means. Control means for controlling one Wherein the reception point storage unit is to overwrite update until an output signal of the reception wave maximum value determination unit.

これにより、受信波形の最大振幅の部分で受信波最大値判定手段による判定点を設定し、安定して受信波判定を動作させるとともに、その前の零クロス点を伝播時間計測に用いることができるので、誤差の少ない伝播時間を計測することができるとともに、計測時間を短縮化できることで省電力動作を実現することが可能になる。さらにトリガレベルを設定する回路を省略による省電力動作を実現できる。 As a result, the determination point by the reception wave maximum value determination means can be set at the maximum amplitude portion of the reception waveform, and the reception wave determination can be operated stably, and the previous zero cross point can be used for the propagation time measurement. Therefore, it is possible to measure the propagation time with less error and to realize the power saving operation by shortening the measurement time. Furthermore, a power saving operation can be realized by omitting a circuit for setting the trigger level.

第２の発明は、特に第１の発明で制御手段は受信点検知手段の出力を記憶する受信点記憶手段への通電を初回のみ長時間とする電源供給手段を有することにより、最初の計測時は本来受信波が到達するよりも前に受信波検知手段の出力を記憶する準備をすることで確実に受信波をとらえることが可能になる。 According to a second aspect of the invention, in particular, in the first aspect of the invention, the control means has power supply means for energizing the reception point storage means for storing the output of the reception point detection means for a long time only for the first time. It is possible to reliably capture the received wave by preparing for storing the output of the received wave detecting means before the received wave originally arrives.

第３の発明は、特に第１の発明で制御手段で受信点検知手段の出力を記憶する受信点記憶手段への通電を２回目以降、前回の値を基に短く通電するよう電源供給手段のタイミングを調節することにより、受信波が到達する直前から受信波検知手段の出力を記憶する準備をすることで確実に受信波をとらえるとともに省電力動作が可能になる。 According to a third aspect of the present invention, in particular, the power supply means in the first aspect of the invention supplies the energization to the reception point storage means for storing the output of the reception point detection means by the control means for the second and subsequent times based on the previous value. By adjusting the timing, preparation for storing the output of the reception wave detection means immediately before the reception wave arrives makes it possible to reliably capture the reception wave and to save power.

第４の発明は、特に第１の発明で制御手段は受信点検知手段の出力が予め定めた回数より多くなると信号を出すトリガ手段を有し電源供給手段は前記トリガ手段の出力により受信点検知手段の出力を記憶する受信点記憶手段への通電を開始することにより、確実に受信波が到達したことを確認してから受信波検知手段の出力を記憶する準備をすることで信頼性が向上するとともにさらに短時間動作による省電力動作が可能になる。 According to a fourth aspect of the present invention, in particular, in the first aspect, the control means includes trigger means for outputting a signal when the output of the reception point detection means exceeds a predetermined number of times, and the power supply means detects the reception point by the output of the trigger means. By starting energization to the receiving point storage means that stores the output of the means, it is confirmed that the received wave has arrived reliably, and then preparing to store the output of the received wave detection means, thereby improving the reliability In addition, a power saving operation by a short time operation becomes possible.

第５の発明は、特に第１の発明で制御手段で制御手段は受信波最大値判定手段の出力後の受信点検知手段の出力と、受信点記憶手段の値の差を演算する時間検定手段を有し、前記時間検定手段の値が予め定めた値以内であれば計測を有効とすることで、ノイズなどによる零クロス点の誤検知を防止することができ正確な零クロス点を選定することで信頼性の向上が可能になる。 According to a fifth aspect of the invention, in particular, in the first aspect, the control means is a time verification means for calculating a difference between the output of the reception point detection means after the output of the reception wave maximum value determination means and the value of the reception point storage means. If the value of the time verification means is within a predetermined value, the measurement is validated to prevent erroneous detection of the zero cross point due to noise or the like, and an accurate zero cross point is selected. This can improve reliability.

第６の発明は、特に第１の発明で制御手段は受信波最大値判定手段の出力後の受信点検知手段の出力後予め定めた時間経過後に電源供給手段を介して受信点記憶手段への電源供給を停止することにより、余分な零クロス点を計測して記憶する動作を停止することができ省電力動作を実現することが可能になる。 According to a sixth aspect of the present invention, in particular, in the first aspect, the control means supplies the reception point storage means via the power supply means after elapse of a predetermined time after the output of the reception point detection means after the output of the reception wave maximum value determination means. By stopping the power supply, it is possible to stop the operation of measuring and storing an extra zero cross point, and to realize a power saving operation.

第７の発明は、特に第１の発明から第６の発明のいずれか１つにおける流速または流量計側装置の制御手段としてコンピュータを機能させるためのプログラムを有する構成としたもので、これにより測定方法の動作設定、変更が容易にでき、また経年変化などにも柔軟に対応できるためよりフレキシブルに計測の精度向上や省電力動作を行うことができる。 The seventh aspect of the invention is a configuration having a program for causing a computer to function as the control means of the flow velocity or flowmeter side device in any one of the first to sixth aspects of the invention. It is possible to easily set and change the operation of the method and flexibly cope with aging, etc., so that the measurement accuracy can be improved and the power saving operation can be performed more flexibly.

（実施の形態１）
実施の形態１に関する本発明の流速または流量計測装置について説明する。 (Embodiment 1)
The flow velocity or flow rate measuring device of the present invention relating to Embodiment 1 will be described.

図１は本実施例の構成を示す流速または流量計測装置のブロック図である。図１おいて、本発明の超音波流量計は被測定流体の流れる流路３１と、前記流路３１に配置された超音波を送受信する第１の振動子３２、第２の振動子３３を設置し、前記第１の振動子３２と前記第２の振動子３３を駆動する送信手段３４と、前記第１の振動子３２と前記第２の振動子３３の受信信号を受け信号を増幅する受信手段３５と、受信手段３５の信号が予め定めた範囲になると信号を出す受信点検知手段３７と、前記受信点検知手段３７の出力を記憶する受信点記憶手段３８と、前記受信点記憶手段３８の信号を用いて振動子間を伝搬した超音波信号の伝搬時間を計時する計時手段３９と、前記計時手段３９の計時差に基づいて流量を算出する流量演算手段４０とを有するものである。 FIG. 1 is a block diagram of a flow velocity or flow rate measuring apparatus showing the configuration of this embodiment. In FIG. 1, an ultrasonic flowmeter of the present invention includes a flow path 31 through which a fluid to be measured flows, a first vibrator 32 and a second vibrator 33 that transmit and receive ultrasonic waves arranged in the flow path 31. Installed, a transmission means 34 for driving the first vibrator 32 and the second vibrator 33, and received signals of the first vibrator 32 and the second vibrator 33, amplifies the signal. A receiving means 35; a receiving point detecting means 37 for outputting a signal when the signal of the receiving means 35 falls within a predetermined range; a receiving point storing means 38 for storing the output of the receiving point detecting means 37; and the receiving point storing means. 38 includes time measuring means 39 for measuring the propagation time of the ultrasonic signal propagated between the vibrators using the 38 signals, and a flow rate calculating means 40 for calculating the flow rate based on the time difference of the time measuring means 39. .

また、図４は図１のブロック図における受信手段３５周辺のブロック図である。受信手段３５の最大信号を検知する受信波最大値判定手段４３を有している。さらに、送信手段３４と第１の振動子３２、および第２の振動子３３と受信手段３５の間に切換手段４１を設け、第１の振動子３２と第２の振動子３３が超音波の送受信を切換えて動作するようにしている。 FIG. 4 is a block diagram around the receiving means 35 in the block diagram of FIG. A reception wave maximum value determination unit 43 that detects the maximum signal of the reception unit 35 is provided. Further, a switching means 41 is provided between the transmission means 34 and the first vibrator 32, and between the second vibrator 33 and the reception means 35, and the first vibrator 32 and the second vibrator 33 are ultrasonic waves. It operates by switching between transmission and reception.

制御手段４２は、前記送信手段３４と前記受信手段３５と受信点検知手段３７と、受信点記憶手段３８と、前記計時手段３９と前記流量演算手段４０と前記切換手段４１と前記受信波最大値判定手段４３との少なくとも１つを制御する The control means 42 includes the transmission means 34, the reception means 35, the reception point detection means 37, the reception point storage means 38, the time measurement means 39, the flow rate calculation means 40, the switching means 41, and the received wave maximum value. Control at least one of the judging means 43

通常の流速または流量計測の動作を説明する。制御手段４２からスタート信号を受けた送信手段３４が第１の振動子３２を一定時間パルス駆動行うと同時に計時手段３９は時間計測始める。パルス駆動された第１の振動子３２からは超音波が送信される。第１の振動子３２から送信した超音波は被測定流体中を伝搬し、第２の振動子３３で受信される。第２の振動子３３の受信出力は、受信手段３５で信号を増幅された後、予め定められている受信タイミングの信号レベルで超音波の受信を決定する。例えば図３における受信波がＶｒｅｆを超えた後、次の零クロス点ｔａを受信波が到達した点とすると、超音波の受信を決定した時点（ここではｔａ点）で計時手段３９の動作を停止し、その時間情報ｔから（式１）によって流速を求める（計時手段３９から得た測定時間をｔ、超音波振動子間の流れ方向の有効距離をＬ、確度をφ、音速をｃ、被測定流体の流速をｖとする）。
ｖ＝（１／ｃｏｓφ）＊（Ｌ／ｔ）−ｃ・・・（式１）
受信手段３５は通常コンパレータによって基準電圧と受信信号を比較するようになっていることが多い。 A normal flow rate or flow rate measurement operation will be described. Upon receipt of the start signal from the control means 42, the transmission means 34 pulse-drives the first vibrator 32 for a certain time, and at the same time, the time measuring means 39 starts measuring time. An ultrasonic wave is transmitted from the pulse-driven first vibrator 32. The ultrasonic wave transmitted from the first vibrator 32 propagates through the fluid to be measured and is received by the second vibrator 33. The reception output of the second vibrator 33 amplifies the signal by the receiving means 35 and then determines the reception of the ultrasonic wave at the signal level at a predetermined reception timing. For example, if the received wave reaches the next zero cross point ta after the received wave in FIG. 3 exceeds Vref, the operation of the time measuring means 39 is performed when the reception of the ultrasonic wave is determined (here, the ta point). The flow rate is calculated from the time information t by (Equation 1) (the measurement time obtained from the time measuring means 39 is t, the effective distance in the flow direction between the ultrasonic transducers is L, the accuracy is φ, the sound velocity is c, The flow velocity of the fluid to be measured is v).
v = (1 / cosφ) * (L / t) −c (Expression 1)
The receiving means 35 is usually configured to compare the reference voltage and the received signal by a comparator.

また、第１の超音波振動子３２と第２の超音波振動子３３との送信、受信方向を切り替え、被測定流体の上流から下流と下流から上流へのそれぞれの伝搬時間を測定し、（式２、３，４）より速度ｖを求めることができる。
（上流から下流への測定時間時間をｔ１、下流から上流への測定時間時間をｔ２とする）ｔ１＝Ｌ／（ｃ＋ｖ＊ｃｏｓφ）・・・・・・・・（式２）
ｔ２＝Ｌ／（ｃ−ｖ＊ｃｏｓφ）・・・・・・・・（式３）
ｖ＝（Ｌ／２＊ｃｏｓφ）＊（（１／ｔ１）−（１／ｔ２））・・・（式４）
この方法によれば音速の変化の影響を受けずに流度を測定することが出来るので、流速・流量・距離などの測定に広く利用されている。流速ｖが求まると、それに流路３１の断面積を乗ずることにより流量を導くことができる。 Further, the transmission and reception directions of the first ultrasonic transducer 32 and the second ultrasonic transducer 33 are switched, and the respective propagation times of the fluid under measurement from upstream to downstream and from downstream to upstream are measured. The speed v can be obtained from Equations 2, 3, and 4).
(Measurement time from upstream to downstream is t1, and measurement time from downstream to upstream is t2.) T1 = L / (c + v * cosφ) (Equation 2)
t2 = L / (c−v * cos φ) (Equation 3)
v = (L / 2 * cosφ) * ((1 / t1) − (1 / t2)) (Expression 4)
According to this method, the flow rate can be measured without being affected by the change in the sound speed, and thus it is widely used for measuring the flow velocity, the flow rate, the distance, and the like. When the flow velocity v is obtained, the flow rate can be derived by multiplying it by the cross-sectional area of the flow path 31.

通常は、この一連の送信から受信動作を行う前に受信波の大きさをある程度一定にするためにオートゲイン動作を行う。この動作を図４の受信手段３５を含めて説明する。受信手段３５には受信側の超音波振動子の信号を増幅する増幅手段３５−１と増幅手段の出力を用い受信波の信号が一定レベルになると信号を出す受信波判定手段３６と、増幅手段の出力で零クロス点を判定する受信点検知手段３７と、増幅手段の出力で受信波の最大値を検知する受信波最大値判定手段４３がある。 Usually, before performing the receiving operation from this series of transmissions, the auto gain operation is performed in order to make the magnitude of the received wave constant to some extent. This operation will be described including the receiving means 35 of FIG. The receiving means 35 includes an amplifying means 35-1 for amplifying the signal of the ultrasonic transducer on the receiving side, an output of the amplifying means, a received wave determining means 36 for outputting a signal when the received wave signal reaches a certain level, There is a reception point detection means 37 for determining the zero cross point by the output of, and a reception wave maximum value determination means 43 for detecting the maximum value of the reception wave by the output of the amplification means.

受信波判定手段３６は受信波が到達したことを判定するためのトリガレベルを設定するトリガレベル設定手段３６−１と、前記トリガレベル判定手段３６−１と増幅手段３５−１の出力を比較して受信波到達信号を送出する受信波到達比較手段３６−２からなる。 The received wave determining means 36 compares the trigger level setting means 36-1 for setting the trigger level for determining that the received wave has arrived, and the outputs of the trigger level determining means 36-1 and the amplifying means 35-1. Reception wave arrival comparison means 36-2 for sending a reception wave arrival signal.

受信点検知手段３７は零クロス点を判断する零基準手段３７−１と、前記零基準手段３７−１と増幅手段３５−１の出力を比較して零クロス点となる信号を送出する零クロス比較手段３７−２からなる。 The reception point detecting means 37 compares the outputs of the zero reference means 37-1 for determining the zero cross point and the zero reference means 37-1 and the amplifying means 35-1 to send out a signal which becomes the zero cross point. Comparing means 37-2.

また、受信波判定手段４３は受信波の最大値を判定するための第１の最大値判定手段４３−１と第２の最大値判定手段４３−２と、前記最大値判定手段を切換える判定値切換手段４３−３と、前記判定値切換手段４３−３からの出力信号と増幅手段３５−１の出力を比較して受信波最大値信号を送出する受信波最大値比較手段４３−４からなる。 The received wave determining means 43 is a first maximum value determining means 43-1 and a second maximum value determining means 43-2 for determining the maximum value of the received wave, and a determination value for switching the maximum value determining means. A switching means 43-3, and a received wave maximum value comparing means 43-4 for comparing the output signal from the judgment value switching means 43-3 with the output of the amplifying means 35-1 and sending out a received wave maximum value signal. .

オートゲインの動作は受信波判定手段４３を用いて行っている。制御手段４２にはオートゲイン調整手段４２−１を有している。最初にオートゲイン調整手段４２−１は判定切換手段４３−３を第２の最大値判定手段４３−２側に切換えておく。第２の最大値判定手段４３−２は電圧値として図３のＶＬを出力する。受信波が増幅手段３５−１で増幅されて受信波最大値比較手段４３−４に到達した時に受信波の最大値がＶＬより小さいと受信波最大値比較手段４３−４の出力は変化しない。このためオートゲイン調整手段４２−１は増幅手段３５−１の増幅度を大きくするように信号を出す。そうして受信波の最大値がＶＬより大きくなるまで増幅度を上げると、受信波が到達した時に受信波最大値比較手段４３−４の出力はＶＬを越えた時点で信号が変化する。これで受信波の大きさがある一定レベルより大きくすることができた。 The operation of the auto gain is performed using the reception wave determination means 43. The control means 42 has an automatic gain adjustment means 42-1. First, the auto gain adjusting means 42-1 switches the determination switching means 43-3 to the second maximum value determining means 43-2 side. The second maximum value determining means 43-2 outputs VL in FIG. 3 as a voltage value. If the maximum value of the received wave is smaller than VL when the received wave is amplified by the amplifying unit 35-1 and reaches the received wave maximum value comparing unit 43-4, the output of the received wave maximum value comparing unit 43-4 does not change. For this reason, the auto gain adjusting means 42-1 outputs a signal so as to increase the amplification degree of the amplifying means 35-1. If the amplification is increased until the maximum value of the received wave becomes larger than VL, the signal of the output of the received wave maximum value comparing means 43-4 changes when the received wave reaches VL. As a result, the magnitude of the received wave can be made larger than a certain level.

ただし、受信波の増幅度があまり大きすぎると波形が歪んだり受信回路の電力が余計に消費したりして不適切である。このため一旦受信信号がＶＬを越えるとオートゲイン調整手段４２−１は判定切換手段４３−３を第１の最大値判定手段４３−１側に切換えておく。第１の最大値判定手段は電圧値として図３のＶＨを出力する。受信波が増幅手段３５−１で増幅されて受信波最大値比較手段４３−４に到達した時に受信波の最大値がＶＨより小さいと受信波最大値比較手段４３−４の出力は変化しない。この場合、受信信号の最大値はＶＨとＶＬの間に調整されたことになる。 However, if the amplification degree of the received wave is too large, the waveform is distorted or the power of the receiving circuit is consumed excessively, which is inappropriate. For this reason, once the received signal exceeds VL, the automatic gain adjusting means 42-1 switches the determination switching means 43-3 to the first maximum value determining means 43-1 side. The first maximum value determination means outputs VH in FIG. 3 as a voltage value. If the maximum value of the received wave is smaller than VH when the received wave is amplified by the amplifying unit 35-1 and reaches the received wave maximum value comparing unit 43-4, the output of the received wave maximum value comparing unit 43-4 does not change. In this case, the maximum value of the received signal is adjusted between VH and VL.

しかし、オートゲイン調整手段４２−１は増幅手段３５−１の増幅度を大きくしすぎると受信波の最大値がＶＨより大きくなり、受信波が到達した時に受信波最大値比較手段４３−４の出力はＶＨを越えた時点で信号が変化する。これは受信波の最大値が大きくなりすぎたことを示すためオートゲイン調整手段４２−１は増幅手段３５−１の増幅度を小さくする。この動作を行うことにより受信波の最大値が常にＶＬとＶＨの間に収まるよう受信波の振幅を調整するのがオートゲイン動作である。 However, if the auto gain adjusting means 42-1 increases the amplification degree of the amplifying means 35-1 too much, the maximum value of the received wave becomes larger than VH, and when the received wave arrives, the received wave maximum value comparing means 43-4 The signal changes when the output exceeds VH. Since this indicates that the maximum value of the received wave has become too large, the auto gain adjusting means 42-1 reduces the amplification degree of the amplifying means 35-1. By performing this operation, the auto gain operation adjusts the amplitude of the received wave so that the maximum value of the received wave always falls between VL and VH.

オートゲイン動作により受信波形の大きさがある程度一定の振幅になった後は、受信波判定手段３６を用い受信点を求めていく。トリガレベル設定手段３６−１の出力をＶｒｅｆとする。 After the size of the received waveform becomes constant to some extent by the auto gain operation, the reception point is determined using the received wave determination means 36. The output of the trigger level setting means 36-1 is set to Vref.

動作を図２のタイミング図と図３の受信波形で説明する。制御手段４２による時刻ｔ０における開始信号から計測を開始するとともに送信手段３４を介して第１の超音波振動子３２を駆動する。そこで発生した超音波信号は流路内を伝搬し時刻ｔ１で第１の超音波振動子３２から出た超音波は第２の超音波振動子３３に到達する。その受信信号は受信手段３５で増幅され、その信号レベルが予め定めたトリガレベル設定手段３６−１の出力であるＶｒｅｆになると受信波判定手段３６が受信波が到達したことを判定して信号を出す。この信号を基に受信点検知手段３７が動作を開始し、Ｖｒｅｆ後の最初の零クロス点を受信点として信号を出し、この点までの時間を計時手段３９で求める。切換手段４１で送受信を切換えて同様の動作を行い計時手段３９で求めた時間と先ほど求めた時間の差に基づいて流量演算手段４０が流量を算出する。 The operation will be described with reference to the timing chart of FIG. 2 and the received waveform of FIG. Measurement is started from the start signal at time t 0 by the control means 42 and the first ultrasonic transducer 32 is driven via the transmission means 34. The ultrasonic signal generated there propagates through the flow path, and the ultrasonic wave emitted from the first ultrasonic transducer 32 reaches the second ultrasonic transducer 33 at time t1. The received signal is amplified by the receiving means 35, and when the signal level becomes Vref which is the output of the predetermined trigger level setting means 36-1, the received wave determining means 36 determines that the received wave has arrived and outputs the signal. put out. Based on this signal, the reception point detection means 37 starts to operate, outputs a signal with the first zero cross point after Vref as the reception point, and the time until this point is obtained by the time measurement means 39. The switching means 41 switches between transmission and reception to perform the same operation, and the flow rate calculation means 40 calculates the flow rate based on the difference between the time obtained by the time measuring means 39 and the time previously obtained.

ここで図３のＶｒｅｆより後にあるｔａ点を求めるために受信波判定手段３６としてＶｒｅｆ信号を出力するトリガレベル設定手段３６−１と受信波到達比較手段３６−２を準備しなければならない。 Here, in order to obtain the ta point after Vref in FIG. 3, it is necessary to prepare trigger level setting means 36-1 for outputting the Vref signal and received wave arrival comparing means 36-2 as the received wave determining means 36.

またＶｒｅｆを必ず受信波にかかるようにするには受信波の最大振幅を一定にしておく必要があるため受信波最大値判定手段４３−４は必須となる。 In order to ensure that Vref is applied to the received wave, it is necessary to keep the maximum amplitude of the received wave constant, so the received wave maximum value determining means 43-4 is essential.

例えば信号波を１００ｋＨｚ、伝搬時間を１００μｓ前後とすると、ｔａのような零クロス点は５μｓ毎に発生する。 For example, if the signal wave is 100 kHz and the propagation time is around 100 μs, a zero cross point such as ta occurs every 5 μs.

受信波は図３でもわかるようにＶｒｅｆより前にも到達している。これがＶｒｅｆより前の信号を利用できればできるほど超音波の到達時間に不確かな時間が含まれにくくなる。さらに今まで受信点としていたｔａの零クロス点より５μｓ前の信号を利用できれば半周期である５μｓ早く零クロス点を確定できることになるため、例えばｔａまでの伝搬時間が１００μｓであったとするとの５％も計測時間を短縮することが可能になり、消費電流の削減を実現できる。 As can be seen from FIG. 3, the received wave reaches before Vref. As the signal before Vref can be used, the arrival time of the ultrasonic wave is less likely to include an uncertain time. Further, if a signal 5 μs before the zero crossing point of ta which has been used as a reception point can be used, the zero crossing point can be determined 5 μs earlier than a half cycle, so that the propagation time to ta is 100 μs, for example. %, The measurement time can be shortened and current consumption can be reduced.

そこで、Ｖｒｅｆより前の零クロス点を受信波判定手段３６を用いずに検出する方法を説明する。単純に零クロス点を受信波の到達した点、例えば図３のａ点を求めることが出来ればよいが、その場合はＶｒｅｆを設定できない。それに近い次のｂ点を受信波到達点とするとＶｒｅｆは破線のＶｒｅｆ−ｓｕｂとしなければならない。この場合は零信号に近いため流量が流れた場合の波形の変化や少しのノイズ等で反応して誤検知する可能性がある。このような現象を回避して受信波の到達点を判定するには受信波の最大値（ＶＨとＶＬの間に入る受信波）の直前の零クロス点ｔｙを検知するようにすればよい。そうすれば受信波判定手段３６を省略した構成を実現できる。 Therefore, a method for detecting the zero cross point before Vref without using the reception wave determination means 36 will be described. It suffices to simply obtain the point where the received wave arrives at the zero cross point, for example, the point a in FIG. 3, but in that case, Vref cannot be set. If the next b point close to it is a reception wave arrival point, Vref must be a broken line Vref-sub. In this case, since it is close to a zero signal, there is a possibility of erroneous detection by reacting with a change in waveform or a little noise when a flow rate flows. In order to avoid such a phenomenon and determine the arrival point of the received wave, the zero cross point ty immediately before the maximum value of the received wave (received wave entering between VH and VL) may be detected. By doing so, a configuration in which the reception wave determination means 36 is omitted can be realized.

この動作を実現するには制御手段４２による時刻ｔ０における開始信号から計測を開始するとともに送信手段３４を介して第１の超音波振動子３２を駆動する。図３と図４を用いて説明する。そこで発生した超音波信号は流路内を伝搬し時刻ｔ１で第１の超音波振動子３２から出た超音波は第２の超音波振動子３３に到達する。その受信信号は受信手段３５内の増幅手段３５−１で増幅されその信号のピーク値が予め定めた値（ＶＨとＶＬの間）になると受信波最大値判定手段４３が受信波が到達したことを判定して信号を出す。 In order to realize this operation, measurement is started from the start signal at time t0 by the control means 42 and the first ultrasonic transducer 32 is driven via the transmission means 34. This will be described with reference to FIGS. The ultrasonic signal generated there propagates through the flow path, and the ultrasonic wave emitted from the first ultrasonic transducer 32 reaches the second ultrasonic transducer 33 at time t1. The received signal is amplified by the amplifying means 35-1 in the receiving means 35, and when the peak value of the signal reaches a predetermined value (between VH and VL), the received wave maximum value judging means 43 has reached the received wave. Is determined and a signal is output.

その前に零クロス点として予め定めた範囲、例えばプラス１ｍＶ、マイナス１ｍＶ以内に入ると信号を出す受信点検知手段３７が動作を開始している。そうすると図３の点ａになると受信点検知手段３７が信号を出力し、その出力を受信点記憶手段３８が記憶する。記憶する値は送信時点からの経過時間、もしくは経過時間を計測できる特定一定時間幅を有するパルス数等とすると後の演算が容易になる。次に点ｂになると同様に受信点記憶手段３７が信号を出力し、受信点記憶手段３８は上書き更新して最新の受信点データを記憶する。これを点ｃ、ｄと繰返しｔｙの点を記憶した後、受信波のピーク値がＶＨとＶＬの間に入り、受信波最大値判定手段４３が受信波が到達したことを判定して信号を出す。この信号をオートゲイン調整手段４２−２が受けると制御手段４２は、これ以降の零クロス点で受信点見地手段３７が信号を出さないようにするか、もしくは受信点記憶手段３８への書き込みを禁止する。この動作を行うことによりｔｙまでの時間を受信点記憶手段に記憶しているため計時手段３９で伝搬時間を求める。切換手段４１で送受信を切換えて同様の動作を行い計時手段３９で求めた時間と先ほど求めた時間の差に基づいて流量演算手段４０が流量を算出する。 Before that, the reception point detection means 37 which outputs a signal when it falls within a predetermined range as a zero cross point, for example, within plus 1 mV or minus 1 mV, starts operation. Then, when the point a in FIG. 3 is reached, the reception point detection means 37 outputs a signal, and the reception point storage means 38 stores the output. If the value to be stored is the elapsed time from the time of transmission or the number of pulses having a specific fixed time width in which the elapsed time can be measured, the subsequent calculation is facilitated. Next, when the point b is reached, the reception point storage means 37 outputs a signal, and the reception point storage means 38 overwrites and updates and stores the latest reception point data. After storing the points c and d and the point of repetition ty, the peak value of the received wave enters between VH and VL, and the received wave maximum value determining means 43 determines that the received wave has arrived and determines the signal. put out. When this signal is received by the automatic gain adjusting means 42-2, the control means 42 prevents the reception point judging means 37 from outputting a signal at the subsequent zero cross point, or writes to the reception point storage means 38. Ban. By performing this operation, the time until ty is stored in the reception point storage means, so the time measuring means 39 obtains the propagation time. The switching means 41 switches between transmission and reception to perform the same operation, and the flow rate calculation means 40 calculates the flow rate based on the difference between the time obtained by the time measuring means 39 and the time previously obtained.

その結果、今までは図３のｔａまでの伝搬時間をｔｙで確定する。具体的にはＴｙはＴａ＋Ｔｆとなり送信周波数の半周期Ｔｆだけ伝搬時間の計測動作時間が長くなるが、Ｖｒｅｆを構成する回路を省略することができることになる。 As a result, the propagation time up to ta in FIG. Specifically, Ty becomes Ta + Tf, and the measurement operation time of the propagation time becomes longer by the half period Tf of the transmission frequency, but the circuit constituting Vref can be omitted.

これにより、上流側の超音波振動子と下流側の超音波振動子間を伝播する超音波の伝播時間、即ち、超音波の到達時間を受信波最大値点よりも前で計測することができる。このため、計測した超音波の伝搬時間あるいは到達時間に含まれる誤差を小さくすることができ、高精度な流れ計測を実現しつつ、回路の省略による省電力動作を実現できる。 Thereby, the propagation time of the ultrasonic wave propagating between the upstream ultrasonic transducer and the downstream ultrasonic transducer, that is, the arrival time of the ultrasonic wave can be measured before the reception wave maximum value point. . For this reason, an error included in the propagation time or arrival time of the measured ultrasonic wave can be reduced, and a power saving operation can be realized by omitting a circuit while realizing highly accurate flow measurement.

また受信点記憶手段３７の出力を記憶する受信点記憶手段３８は記憶動作を行うのに電力を消費するがどの時点から通電して良いかは前もってわかっていない場合が多い。あま
り早く投入すると電力が無駄になるし、受信点を通過してから通電しても意味は無い。そこで図６に示すように制御手段４２内に電源供給手段４４を設けて電力制御を行う。タイミングは図７で説明する。一番初めに計測を開始する場合はＴａが不明である。超音波振動子３２，３３の物理的距離からおおよその時間は推定できるが確かでは無い。そこで制御手段４２は電源供給手段４４を用いて受信点記憶手段３８への通電タイミングを調節する。 The reception point storage means 38 for storing the output of the reception point storage means 37 consumes power to perform the storage operation, but it is often unknown in advance from which time point the power supply can be energized. If it is turned on too early, power is wasted, and there is no point in energizing after passing the reception point. Therefore, as shown in FIG. 6, power supply means 44 is provided in the control means 42 to perform power control. The timing will be described with reference to FIG. When measurement is started first, Ta is unknown. Although the approximate time can be estimated from the physical distance between the ultrasonic transducers 32 and 33, it is not certain. Therefore, the control unit 42 uses the power supply unit 44 to adjust the energization timing to the reception point storage unit 38.

まず、時刻ｔ０における開始信号から計測を開始するとともに送信手段３４を介して第１の超音波振動子３２を駆動する。そこで発生した超音波信号は流路内を伝搬し時刻ｔ１で第１の超音波振動子３２から出た超音波は第２の超音波振動子３３に到達する。その前時刻ｔ２に電源供給手段４３を用いて受信点記憶手段３８への通電を開始する。ｔ２はｔ１より十分短い時間とする。 First, measurement is started from a start signal at time t 0 and the first ultrasonic transducer 32 is driven via the transmission unit 34. The ultrasonic signal generated there propagates through the flow path, and the ultrasonic wave emitted from the first ultrasonic transducer 32 reaches the second ultrasonic transducer 33 at time t1. At the previous time t2, energization to the reception point storage means 38 is started using the power supply means 43. t2 is a time sufficiently shorter than t1.

このように、制御手段４２は受信点検知手段３７の出力を記憶する受信点記憶手段３８への通電を初回のみ長時間とする電源供給手段４４を有することにより、最初の計測時は本来受信波が到達するよりも前に受信波検知手段の出力を記憶する準備をすることで確実に受信波をとらえることが可能になる。 In this way, the control means 42 has the power supply means 44 for energizing the reception point storage means 38 for storing the output of the reception point detection means 37 for a long time only for the first time. By preparing to store the output of the received wave detection means before the wave arrives, it is possible to reliably receive the received wave.

また初回により受信点が確定し伝搬時間が求まる。その場合は２回目以降の通電時間を調整することが容易になる。 In addition, the reception point is determined by the first time and the propagation time is obtained. In that case, it becomes easy to adjust the energization time after the second time.

例えば図７で最初はｔ２において受信点記憶手段３８への通電を開始したが、実際に超音波が伝搬して受信したのはｔ１である。次の計測においては伝搬時間が大幅に変化することが無いため制御手段４２にある電源供給手段４４はｔ１に近くてまだ受信信号が到達していないｔ２まで通電するのを待つことが可能になる。３回目は２回目の伝搬時間を用いたり、または１回目と２回目の移動平均を用いたりして伝播時間を予想し、通電時間を極力短くすることが可能になる。 For example, in FIG. 7, at first, energization of the reception point storage unit 38 is started at t2, but it is at t1 that the ultrasonic wave has actually propagated and received. In the next measurement, since the propagation time does not change significantly, the power supply means 44 in the control means 42 can wait for energization until t2 where the reception signal is not reached yet near t1. . The third time uses the second propagation time, or uses the first and second moving averages to predict the propagation time, thereby making it possible to shorten the energization time as much as possible.

このように制御手段４２で受信点検知手段３７の出力を記憶する受信点記憶手段３８への通電を２回目以降、前回の値を基に短く通電するよう電源供給手段４４のタイミングを調節することにより、受信波が到達する直前から受信波検知手段の出力を記憶する準備をすることで確実に受信波をとらえるとともに省電力動作が可能になる。 In this way, the control means 42 adjusts the timing of the power supply means 44 so that the reception point storage means 38 for storing the output of the reception point detection means 37 is energized for the second time and thereafter, based on the previous value. Thus, by preparing for storing the output of the reception wave detection means immediately before the reception wave arrives, the reception wave can be reliably captured and a power saving operation can be performed.

この説明では受信点記憶手段３８の通電時間のみ調節するようになっているが、受信信号を増幅する受信手段３５から下流の動作が電源投入時に不安定な状態が長く続かなければそれら一式もしくは特に電力を必要とする部位の通電を電源供給手段４４で調整すればさらに省電力が可能になる。 In this description, only the energization time of the reception point storage means 38 is adjusted. However, if the operation downstream from the reception means 35 for amplifying the reception signal does not continue to be unstable for a long time when the power is turned on, a set of them or particularly If the power supply means 44 adjusts the energization of the part that requires power, further power saving can be achieved.

また図５の零クロス点ａからｄの状態が図７のｔ３からｔ１の付近を拡大したものと同等とする。この場合、受信手段３５は受信信号が到達する前から動作し、受信点判定手段３７も動作しａ，ｂ，ｃ，ｄ毎に信号を送出している。図８において制御手段４２はこの受信点判定手段３７の出力信号をカウントし予め予め定めた回数例えば２回とするとｂ点まで受信点が到達するとトリガ手段４５が電源供給手段４４を介して受信点記憶手段３８への通電を開始する。受信確定するｔｙまでの通電時間をより短くすることができる。 Further, it is assumed that the state of the zero cross points a to d in FIG. 5 is equivalent to an enlarged state in the vicinity of t3 to t1 in FIG. In this case, the reception unit 35 operates before the reception signal arrives, and the reception point determination unit 37 also operates to send a signal for each of a, b, c, and d. In FIG. 8, the control means 42 counts the output signal of the reception point determination means 37, and when the number of times reaches a predetermined number of times, for example, twice, the trigger means 45 passes the power supply means 44 through the power supply means 44 when the reception point reaches the point b. Energization of the storage means 38 is started. It is possible to shorten the energization time until ty when reception is confirmed.

このように制御手段４２は受信点検知手段３７の出力が予め定めた回数より多くなると信号を出すトリガ手段４５を有し電源供給手段４４は前記トリガ手段の出力により受信点検知手段３７の出力を記憶する受信点記憶手段３８への通電を開始することにより、確実に受信波が到達したことを確認してから受信波最大値判定手段４３の出力を記憶する準備をすることで信頼性が向上するとともにさらに短時間動作による省電力動作が可能になる
。 In this way, the control means 42 has the trigger means 45 that outputs a signal when the output of the reception point detection means 37 exceeds a predetermined number of times, and the power supply means 44 outputs the output of the reception point detection means 37 by the output of the trigger means. By starting energization to the reception point storage means 38 to be stored, the reliability is improved by preparing to store the output of the reception wave maximum value determination means 43 after confirming that the reception wave has arrived reliably. In addition, a power saving operation by a short time operation becomes possible.

また受信信号が図５の零クロス点ｔｙより先ＶＨからＶＬの間になった後は受信手段３５より後段の回路は計時手段３９、流量演算手段４０以外を動作する必要が無い。したがって受信波最大値判定手段４３により受信波がＶＨからＶＬに入ったことを検知すると制御手段４２は受信点記憶手段３８への通電を停止して省電力動作を行うとともに必要のない受信回路の通電動作を停止することが可能である。停止を行う時点はＶＨとＶＬの間に入ったかを越えた直後でも良いし、また通電停止時の信号によりノイズが発生して計時手段３９などの動作に悪影響を与えてもよくないため次の零クロス点ｔｂを検知してから通電停止してもよい。 Further, after the received signal is between VH and VL before the zero cross point ty in FIG. 5, the circuit subsequent to the receiving means 35 does not need to operate other than the time measuring means 39 and the flow rate calculating means 40. Therefore, when the received wave maximum value judging means 43 detects that the received wave has entered from VL to V L, the control means 42 stops the energization to the receiving point storage means 38 to perform power saving operation and the unnecessary receiving circuit of the receiving circuit. The energization operation can be stopped. The time point at which the stop is performed may be immediately after exceeding or exceeding the range between VH and VL, and noise may be generated by a signal at the time of stopping energization, which may adversely affect the operation of the timing means 39 and the like. The energization may be stopped after detecting the zero cross point tb.

このように制御手段４２は受信波最大値判定手段４３の出力後の受信点検知手段３７の出力後予め定めた時間経過後に電源供給手段４４を介して受信点記憶手段３８への電源供給を停止することにより、余分な零クロス点を計測して記憶する動作を停止することができ省電力動作を実現することが可能になる。 In this way, the control means 42 stops the power supply to the reception point storage means 38 via the power supply means 44 after elapse of a predetermined time after the output of the reception point detection means 37 after the output of the reception wave maximum value determination means 43. By doing so, it is possible to stop the operation of measuring and storing the extra zero cross point, and to realize the power saving operation.

また、図４における零クロス点は受信波にノイズが重畳されていなければほぼ送信周波数の半分の周期で発生してきている。しかし実際に流路に流体が流れている場合はその流体により下流側で何かが動作している。この動作や他の外来ノイズ等により受信波にスパイク状の信号が重畳されることもある。この場合ノイズが零クロスした点を受信点とすると伝搬時間の計算が大きくずれてします。これを防止するため図９に示すように制御手段４２に時間検定手段４６を設ける。 In addition, the zero cross point in FIG. 4 is generated at a period substantially half the transmission frequency if noise is not superimposed on the received wave. However, when a fluid actually flows in the flow path, something is operating downstream by the fluid. A spike-like signal may be superimposed on the received wave due to this operation or other external noise. In this case, if the point where the noise crosses zero is taken as the receiving point, the calculation of the propagation time will deviate greatly. In order to prevent this, the control means 42 is provided with a time verification means 46 as shown in FIG.

時間検定手段４６を用いた場合の動作を説明する。まず図５と同様に零クロス点を受信し始めると受信点検知手段３７が信号を出力し、その出力を受信点記憶手段３８が記憶する。記憶する値は送信時点からの経過時間、もしくは経過時間を計測できる特定一定時間幅を有するパルス数等とすると後の演算が容易になる。次に点ｂになると同様に受信点記憶手段３７が信号を出力し、受信点記憶手段３８は上書き更新して最新の受信点データを記憶する。これを点ｃ、ｄと繰返しｔｙの点を記憶した後、受信信号がＶＨとＶＬの間に入る。 The operation when the time verification means 46 is used will be described. First, similarly to FIG. 5, when the reception of the zero cross point is started, the reception point detection means 37 outputs a signal, and the reception point storage means 38 stores the output. If the value to be stored is the elapsed time from the time of transmission or the number of pulses having a specific fixed time width in which the elapsed time can be measured, the subsequent calculation is facilitated. Next, when the point b is reached, the reception point storage means 37 outputs a signal, and the reception point storage means 38 overwrites and updates and stores the latest reception point data. After storing the points c and d and the point of ty, the received signal enters between VH and VL.

この時初めて受信波最大値判定手段４３が信号を出力する。制御手段４２はこの受信波最大値判定手段４３から信号が出力されると、これ以降の零クロス点で受信点検知手段３７が信号を出さないようにするか、もしくは受信点記憶手段３８への書き込みを禁止する。 At this time, the received wave maximum value judging means 43 outputs a signal for the first time. When a signal is output from the received wave maximum value determining means 43, the control means 42 prevents the reception point detecting means 37 from outputting a signal at the subsequent zero cross point, or outputs the signal to the reception point storage means 38. Prohibit writing.

そして次の零クロス点ｔｂの時間を受信点記憶手段３８を介さずに直接制御手段の時間検定手段４５に送る。時間検定手段４５は受信点記憶手段３８にあるｔｙの値とｔｂの値の差を求める。この差が予め定めた範囲内であればｔｙはノイズによるものではないと判断し、ｔｙを用いて流量を演算する。例えば送信周波数が１００ｋＨｚとすると周期の１／２の周期は５μｓとなるそこでｔｙ−ｔｂが予め定めた５μｓ近傍以内であればｔｙは有効な受信点であると判断する。 Then, the time of the next zero cross point tb is sent directly to the time verification means 45 of the control means without going through the reception point storage means 38. The time verification unit 45 obtains the difference between the ty value and the tb value stored in the reception point storage unit 38. Within the scope of this difference is a predetermined ty is determined not to be due to noise, calculates the flow rate using ty. For example, if the transmission frequency is 100 kHz, the half of the period is 5 μs. Therefore, if ty-tb is within a predetermined vicinity of 5 μs, it is determined that ty is an effective reception point.

このように制御手段４２は受信波最大値判定手段４３の出力後の受信点検知手段３７の出力と、受信点記憶手段３８の値の差を演算する時間検定手段４６を有し、前記時間検定手段４６の値が予め定めた値以内であれば計測を有効とすることで、ノイズなどによる零クロス点の誤検知を防止することができ正確な零クロス点を選定することで信頼性の向上が可能になる。 Thus, the control means 42 has the time verification means 46 for calculating the difference between the output of the reception point detection means 37 after the output of the received wave maximum value determination means 43 and the value of the reception point storage means 38, and the time verification If the value of the means 46 is within a predetermined value, it is possible to prevent erroneous detection of the zero cross point due to noise or the like by enabling the measurement, and to improve reliability by selecting an accurate zero cross point. Is possible.

流路や送信方法が予めわかっていれば受信波の最大値点となる波数は予めわかっている
ためその直前の零クロス点は上流、下流と切換えても同じ伝搬距離を伝送してきたものとして用いることが可能である。 If the flow path and transmission method are known in advance, the wave number that becomes the maximum value point of the received wave is known in advance, so the zero crossing point immediately before that is used as having transmitted the same propagation distance even if switched upstream and downstream It is possible.

（実施の形態２）
実施の形態２に関する本発明の流速または流量計測装置について説明する。実施の形態１と異なるところは、振動子３２，３３や送信手段３４、受信手段３５、受信手段３５の信号が最大値になると信号を出す受信波最大値判定手段４３、受信手段３５の信号が予め定めた範囲に入ると信号を出す受信点検知手段３７、前記受信点検知手段３７の出力を記憶する受信点記憶手段３８、前記受信点記憶手段３８の信号を用いて振動子間を伝搬した超音波信号の伝搬時間を計時する計時手段３９、前記計時手段３９の計時差に基づいて流量を算出する流量演算手段４０、送受信を切換える切換手段４１、受信手段３５の最大信号を検知する受信波最大値判定手段４３との少なくとも１つを制御する制御手段４２の動作を確実にするためのコンピュータを機能させるためのプログラムを有する記憶媒体４７を用いていることである。 (Embodiment 2)
The flow velocity or flow rate measuring apparatus of the present invention relating to the second embodiment will be described. The difference from the first embodiment is that the signals of the received wave maximum value determining means 43 and the receiving means 35 that output signals when the signals of the vibrators 32 and 33, the transmitting means 34, the receiving means 35, and the receiving means 35 reach the maximum values are obtained. A reception point detection means 37 that outputs a signal when entering a predetermined range, a reception point storage means 38 that stores the output of the reception point detection means 37, and a signal from the reception point storage means 38 is used to propagate between the transducers. Time measuring means 39 for measuring the propagation time of the ultrasonic signal, flow rate calculating means 40 for calculating the flow based on the time difference of the time measuring means 39, switching means 41 for switching between transmission and reception, and received wave for detecting the maximum signal of the receiving means 35 Use of a storage medium 47 having a program for causing a computer to function to ensure the operation of the control means 42 for controlling at least one of the maximum value judging means 43 A.

図１において実施の形態１で示した制御手段４２の動作を行うには、予め実験等によりｔｙを求めるための受信点記憶手段の動作、通電方法を求めておいたり、経年変化、温度変化、システムの安定度に関して動作タイミングなどの相関を求め、ソフトをプログラムとして記憶媒体４７に格納しておく。通常マイクロコンピュータのメモリやフラッシュメモリ等電気的に書き込み可能なものにしておくと利用が便利である。 In order to perform the operation of the control unit 42 shown in FIG. 1 in FIG. 1, the operation of the receiving point storage unit for obtaining ty by an experiment or the like, the energization method, the secular change, the temperature change, Correlation such as operation timing is obtained with respect to the stability of the system, and the software is stored in the storage medium 47 as a program. Usually, it is convenient to use an electrically writable memory such as a microcomputer memory or a flash memory.

切換手段４１の動作により送受信の方向が変化するため条件設定などの個数が増加してくるがこれをコンピュータによる動作で調整すると容易に実現可能である。 Since the direction of transmission / reception changes due to the operation of the switching means 41, the number of condition settings and the like increases, but this can be easily realized by adjusting this by operation by a computer.

このように制御手段４２の動作をプログラムで行うことができるようになると流量演算の補正係数の条件設定、変更や計測間隔の調整などが容易にでき、また経年変化などにも柔軟に対応できるためよりフレキシブルに流速または流量計測の精度向上を行うことができる。なお本実施例において制御手段４２以外の動作もマイコン等によりプログラムで行ってもよい。 As described above, when the operation of the control means 42 can be performed by a program, it is possible to easily set, change, and adjust the measurement interval of the correction coefficient for the flow rate calculation, and to flexibly cope with aging. The accuracy of flow velocity or flow rate measurement can be improved more flexibly. In this embodiment, operations other than the control means 42 may be performed by a program using a microcomputer or the like.

これにより制御手段としてコンピュータを機能させるためのプログラムを有する構成としたもので、測定方法の動作設定、変更が容易にでき、また経年変化などにも柔軟に対応できるためよりフレキシブルに計測の精度向上を行うことができる。 As a result, it has a configuration that has a program for causing the computer to function as a control means, making it easy to set and change the operation of the measurement method and flexibly respond to secular changes, etc. It can be performed.

本発明の流速または流量計測装置は零クロス点を上書きして記憶し続け、受信波が確実に届いたことを示す受信波最大値判定手段に出力信号があるとその動作を停止する。 The flow velocity or flow rate measuring device of the present invention continues to overwrite and memorize the zero cross point, and stops its operation when there is an output signal in the received wave maximum value judging means indicating that the received wave has surely arrived.

これにより、受信波形の振幅の大きい部分に受信波最大値判定手段によるトリガ−点を設定し、安定してトリガ−を動作させるとともに、その前の零クロス点を伝播時間計測に用いることができるので、誤差の少ない伝播時間を計測することができるとともに、回路の簡素化により省電力動作を実現することが可能になる。 As a result, the trigger point by the received wave maximum value determining means can be set at a portion where the amplitude of the received waveform is large, the trigger can be stably operated, and the previous zero cross point can be used for propagation time measurement. Therefore, it is possible to measure the propagation time with less error and to realize a power saving operation by simplifying the circuit.

本発明の流速または流量計測装置の全体ブロック図Overall block diagram of the flow velocity or flow rate measuring device of the present invention （ａ）同計測装置における計測制御手段の動作を示すタイミング図（ｂ）同計測装置における送信波の動作を示すタイミング図（ｃ）同計測装置における受信波および反射波の動作を示すタイミング図(A) Timing diagram showing the operation of the measurement control means in the measuring device (b) Timing diagram showing the operation of the transmitted wave in the measuring device (c) Timing diagram showing the operation of the received wave and the reflected wave in the measuring device 同計測装置における受信波を示すタイミング図Timing chart showing received waves in the same measuring device 同計測装置における受信手段周辺のブロック図Block diagram around the receiving means in the same measuring device 同計測装置における受信波を示すタイミング図Timing chart showing received waves in the same measuring device 本発明の流速または流量計測装置他の動作を示す全体ブロック図Overall block diagram showing other operations of the flow velocity or flow rate measuring device of the present invention （ａ）同計測装置における計測制御手段の動作を示すタイミング図（ｂ）同計測装置における送信波の動作を示すタイミング図（ｃ）同計測装置における受信波および反射波の動作を示すタイミング図(A) Timing diagram showing the operation of the measurement control means in the measuring device (b) Timing diagram showing the operation of the transmitted wave in the measuring device (c) Timing diagram showing the operation of the received wave and the reflected wave in the measuring device 本発明の流速または流量計測装置他の動作を示す全体ブロック図Overall block diagram showing other operations of the flow velocity or flow rate measuring device of the present invention 本発明の流速または流量計測装置他の動作を示す全体ブロック図Overall block diagram showing other operations of the flow velocity or flow rate measuring device of the present invention 従来の流量計測装置の断面図Sectional view of a conventional flow measurement device

３１流路
３２第１の振動子
３３第２の振動子
３４送信手段
３５受信手段
３６受信波判定手段
３７受信点検知手段
３８受信点記憶手段
３９計時手段
４０流量演算手段
４１切換手段
４３受信波最大値判定手段
４２制御手段
４４電源供給手段
４５トリガ手段
４６時間検定手段
４７記憶媒体 31 flow path 32 first vibrator 33 second vibrator 34 transmitting means 35 receiving means 36 received wave determining means 37 receiving point detecting means 38 receiving point storage means 39 timing means 40 flow rate calculating means 41 switching means 43 maximum received wave Value determining means 42 Control means 44 Power supply means 45 Trigger means 46 Time verification means 47 Storage medium

Claims

被測定流体の流れる流路に配置され超音波を送受信する一対の振動子と、
一方の振動子を駆動する送信手段と、
他方の受信側振動子の出力信号を電気信号に変換する受信手段と、
受信手段の信号の最大値を検出して信号を出す受信波最大値判定手段と、
受信手段の信号が予め定めた範囲になると信号を出す受信点検知手段と、
前記受信点検知手段の出力を記憶する受信点記憶手段と、
前記受信点記憶手段の信号を用いて振動子間を伝搬した超音波信号の伝搬時間を計時する計時手段と、
前記計時手段の計時差に基づいて流量を算出する流量演算手段と、
前記送信手段と前記受信手段と前記受信波最大値検知手段と受信点検知手段と前記受信点記憶手段と前記計時手段と前記流量演算手段との少なくとも１つを制御する制御手段とを備え、
前記受信点記憶手段は前記受信波最大値判定手段の出力信号があるまで上書き更新する流速または流量計測装置。 A pair of transducers arranged in the flow path of the fluid to be measured and transmitting and receiving ultrasonic waves;
Transmission means for driving one vibrator;
Receiving means for converting the output signal of the other receiving-side vibrator into an electrical signal;
A received wave maximum value determining means for detecting the maximum value of the signal of the receiving means and outputting a signal;
A receiving point detecting means for outputting a signal when the signal of the receiving means falls within a predetermined range;
Reception point storage means for storing the output of the reception point detection means;
Time measuring means for measuring the propagation time of the ultrasonic signal propagated between the transducers using the signal of the receiving point storage means;
Flow rate calculation means for calculating a flow rate based on the time difference of the time measuring means;
Control means for controlling at least one of the transmission means, the reception means, the received wave maximum value detection means, the reception point detection means, the reception point storage means, the time measurement means, and the flow rate calculation means;
The receiving point storage means is a flow velocity or flow rate measuring device that overwrites and updates until there is an output signal of the received wave maximum value judging means.

制御手段は受信点検知手段の出力を記憶する受信点記憶手段への通電を初回のみ長時間とする電源供給手段を有する請求項１記載の流速または流量計測装置。 2. The flow velocity or flow rate measuring device according to claim 1, wherein the control means has power supply means for energizing the reception point storage means for storing the output of the reception point detection means for a long time only for the first time.

制御手段は受信点検知手段の出力を記憶する受信点記憶手段への通電を２回目以降、前回の値を基に短く通電するよう電源供給手段のタイミングを調節する請求項１記載の流速または流量計測装置。 The flow rate or flow rate according to claim 1, wherein the control means adjusts the timing of the power supply means so that the receiving point storage means for storing the output of the receiving point detection means is energized for the second time and thereafter, based on the previous value. Measuring device.

制御手段は受信点検知手段の出力が予め定めた回数より多くなると信号を出すトリガ手段を有し電源供給手段は前記トリガ手段の出力により受信点検知手段の出力を記憶する受信点記憶手段への通電を開始する請求項１記載の流速または流量計測装置。 The control means includes trigger means for outputting a signal when the output of the reception point detection means exceeds a predetermined number of times, and the power supply means supplies the reception point storage means for storing the output of the reception point detection means by the output of the trigger means. The flow velocity or flow rate measuring device according to claim 1, wherein energization is started.

制御手段は受信波最大値判定手段の出力後の受信点検知手段の出力と、受信点記憶手段の値の差を演算する時間検定手段を有し、前記時間検定手段の値が予め定めた値以内であれば計測を有効とする請求項１記載の流速または流量計測装置。 The control means has time verification means for calculating the difference between the output of the reception point detection means after the output of the received wave maximum value determination means and the value of the reception point storage means, and the value of the time verification means is a predetermined value. The flow velocity or flow rate measuring device according to claim 1, wherein the measurement is effective if the value is within the range.

制御手段は受信波最大値判定手段の出力後の受信点検知手段の出力後予め定めた時間経過後に電源供給手段を介して受信点記憶手段への電源供給を停止する請求項１記載の流速または流量計測装置。 2. The flow rate according to claim 1, wherein the control means stops the power supply to the reception point storage means via the power supply means after the elapse of a predetermined time after the output of the reception point detection means after the output of the reception wave maximum value determination means. Flow measurement device.

請求項１から請求項６のいずれか１項記載の流速または流量計側装置の制御手段としてコンピュータを機能させるためのプログラム。 The program for functioning a computer as a control means of the flow velocity or flowmeter side apparatus of any one of Claims 1-6.