JPS60166821A

JPS60166821A - Flowmeter

Info

Publication number: JPS60166821A
Application number: JP59022556A
Authority: JP
Inventors: Kyoichi Ikeda; 恭一池田; Fumitaka Ohashi; 大橋　章隆
Original assignee: Yokogawa Hokushin Electric Corp
Current assignee: Yokogawa Electric Corp
Priority date: 1984-02-09
Filing date: 1984-02-09
Publication date: 1985-08-30

Abstract

PURPOSE:To realize a flowmeter utilizing Doppler effect not affected by sound velocity of a fluid which capable of measuring the flow rate in a homogenized medium by providing an arithmetic means of computing the frequency difference between an excitation signal applied to an exciting means and a detection signal outputted from an ultrasonic wave detection means. CONSTITUTION:An exciting means 3, a receiving ultrasonic transducer 4 and an amplification circuit 5 forms a self-exciting loop, which generates a vibration by a resonance frequency in the system including a pipeline and a fluid. As a result, a standing wave is generated in a passage, a part of vibration energy propagates through the fluid and is dispersed to the downstream and the upstream as ultrasonic wave. When the fluid stands still, the frequency of a signal Sr2 detected by an ultrasonic wave detection means 7 provided on the downstream (possible on the upstream) is the same as that of an excitation signal Sa. But, when the fluid moves, the ultrasonic wave observed at the standing point on the downstream is subjected to a Doppler shift as the field of the standing wave moves (hence, a sound source moves). Since the Doppler shift level fd is proportional to the flow velocity, the flow velocity and flow rate can be determined by measuring the Doppler shift level fd.

Description

【発明の詳細な説明】（発明の利用分野）本発明は、超音波によるドツプラー効果を利用した新し
い流量計に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a new flowmeter that utilizes the Doppler effect caused by ultrasonic waves.

（従来技術）ドプラー効果を流量測定に利用する従来のドプラー流ｆ
ｆｉ　ｉｆは、流体中に超音波を散乱する物体がないと
作動しない上、流体の音速の影響を受けるという問題が
あった。(Prior art) Conventional Doppler flow f that uses the Doppler effect for flow measurement
fi if does not operate unless there is an object in the fluid that scatters ultrasonic waves, and it also has the problem of being affected by the sound speed of the fluid.

（発明の目的）本発明は上記の問題点を解決するためになされたもので
、均質媒体中の流量を測定でき、流体の音速の影響を受
けない、ドプラー効果を利用した超音波流量計を実現す
ることを目的としている。(Object of the Invention) The present invention has been made to solve the above problems, and is an ultrasonic flowmeter that utilizes the Doppler effect, which can measure the flow rate in a homogeneous medium and is not affected by the sound velocity of the fluid. The aim is to achieve this goal.

（発明の概要）本発明の流量計は、流路中に定在波を発生させる励振手
段と、前記励振手段の下流または上流に設（プられた超
音波検出手段と、前記励振手段に加えられる励振信号と
前記超音波検出手段から出力される検出信号との間の周
波数の差を演算する演算手段とを有することを特徴とす
る。(Summary of the Invention) The flowmeter of the present invention includes: an excitation means for generating standing waves in a flow path; an ultrasonic detection means installed downstream or upstream of the excitation means; The ultrasonic wave detection device is characterized by comprising a calculation means for calculating a difference in frequency between an excitation signal output from the ultrasonic detection means and a detection signal output from the ultrasonic detection means.

（実施例）以下本発明を図面を用いて詳しく説明する。(Example) The present invention will be explained in detail below using the drawings.

図は本発明に係わる流」計の一実施例の構成を示す溝成
説明図である。１はその中を流体が流れて流路１１を形
成する管路、２は流速Ｖの流れ、３は流路中に定在波を
発生させる励振手段でここでは圧電素子などの超音波ト
ランデューサを用いたもの、４は同じく受信用の超音波
トランデューサ、５は受信用の前記超音波トランデュー
サ４からの検出出力Ｓｒ１を増幅し前記励振用超音波ト
ランデューサ３に信号３ａを出力する増幅回路、６は前
記励振用超音波トランデューサ３によって流路中に生じ
る定在波、７は前記励振用超音波トランデューサ３の下
流（上流も可能）に設けられた超音波検出手段で超音波
１−ランデ１−ザで構成されたもの、８はこの超音波検
出手段７から出力される検出信号Ｓ　ｒ−２を増幅する
フィルタ増幅器、９は前記励振７段３に加えられる励振
信号Ｓａと前記超音波検出手段７から出力される検出信
号３ｒ２との間の周波数の差を演算する演算手段で、９
１は信号Ｓａと信号Ｓｒ２との間の掛算を行うためのヘ
テロダイン検波器〈掛算器）、９２はこのヘテロダイン
検波器９１の出力に含まれる差の周波数成分のみを取り
出すローパスフィルタ、９３はこのローパスフィルタ９
２の出力信号の周波数をめるための計数器である。The figure is an explanatory diagram showing the structure of an embodiment of the flowmeter according to the present invention. 1 is a pipe through which a fluid flows to form a flow path 11; 2 is a flow with a flow velocity V; 3 is an excitation means for generating standing waves in the flow path; here, an ultrasonic transducer such as a piezoelectric element; 4 is also an ultrasonic transducer for reception, and 5 is an amplification device that amplifies the detection output Sr1 from the ultrasonic transducer 4 for reception and outputs a signal 3a to the ultrasonic transducer 3 for excitation. A circuit, 6 is a standing wave generated in the flow path by the excitation ultrasonic transducer 3, and 7 is an ultrasonic detection means provided downstream (or upstream is possible) of the excitation ultrasonic transducer 3; 8 is a filter amplifier for amplifying the detection signal Sr-2 outputted from the ultrasonic detection means 7; 9 is an excitation signal Sa applied to the excitation 7 stage 3; Calculating means for calculating the difference in frequency between the detection signal 3r2 outputted from the ultrasonic detecting means 7;
1 is a heterodyne detector (multiplier) for performing multiplication between the signal Sa and the signal Sr2, 92 is a low-pass filter that extracts only the frequency component of the difference contained in the output of this heterodyne detector 91, and 93 is this low-pass filter. Filter 9
This is a counter for counting the frequency of the second output signal.

上記のような構成の流量計において、励振手段３、受信
用の超音波トランデューサ４および増幅回路５は自励振
ループを形成するので、管路と流体を含めた系の共振周
波数で振動を発生させる。In the flowmeter configured as described above, the excitation means 3, the receiving ultrasonic transducer 4, and the amplifier circuit 5 form a self-oscillation loop, which generates vibration at the resonant frequency of the system including the pipe and fluid. let

この結果流路中に定在波を生じ、その振動エネルギーの
一部は流体中を伝播し、下流および上流へ超音波として
発散されてゆく。流体が静止している場合には下流（上
流も可能）に設けられた超音波検出手段７で検出される
信号３ｒ２の周波数は励振信号Ｓａと同じであるが、流
体が移動すると定在波の場も移動するため〈音源が移動
することになり）下流の静止点で観測される超音波はド
ツプラーシフトを受ける。定在波の半波長を８１流体中
の音速をＣとすると、定在波の周波数ｆｒはｆｒ−Ｃ，
／２Ｂ　・＝　（１）となる。これは流体が静止しているときに下流に設（プ
られた超音波検出手段７で検出される信号Ｓｒ２の周波
数と同じである。流体が流速Ｖで移動するときに信号８
１゛２の周波数に生じるドツプラーシフトｆｆ１ｆｄはｒｄ＝ｆｒ−Ｃ／　（Ｃ−ｖ　）　−ｆｒ中（１＋ｖ　
／Ｃ）　ｒｒ−ｒｒ　（但しＣ＞ｙ）＝ｆｒ・Ｖ／Ｃ・
・・（２）となる。式（１）および（２）からｆｄ−Ｖ／２Ｂ　・・・（３）となる。すなわちドツプラーシフトｆｆ１ｆｄは流速に
比例しているので、ドツプラーシフト聞［（〕を測定す
ることにより、流速、流ｍを決定することかできる。As a result, standing waves are generated in the flow path, and part of the vibrational energy propagates through the fluid and is dissipated downstream and upstream as ultrasonic waves. When the fluid is stationary, the frequency of the signal 3r2 detected by the ultrasonic detection means 7 provided downstream (or upstream is possible) is the same as the excitation signal Sa, but when the fluid moves, the frequency of the signal 3r2 is the same as that of the excitation signal Sa. Because the field also moves (the sound source moves), the ultrasound observed at a stationary point downstream undergoes a Doppler shift. If the half wavelength of the standing wave is 81 and the speed of sound in the fluid is C, then the frequency fr of the standing wave is fr-C,
/2B ・= (1). This is the same frequency as the signal Sr2 detected by the ultrasonic detection means 7 installed downstream when the fluid is stationary.
The Doppler shift ff1fd occurring at the frequency of 1゛2 is (1+v
/C) rr-rr (C>y)=fr・V/C・
...(2) becomes. From equations (1) and (2), fd-V/2B (3) is obtained. That is, since the Doppler shift ff1fd is proportional to the flow velocity, the flow velocity and the flow m can be determined by measuring the Doppler shift interval [(]).

演算手段９は励振信号ｓａと検出信号Ｓｒ２との間の周
波数の差すなりもドツプラーシフトｍを公知の方法でめ
ることにより、流量を得ている。The calculation means 9 obtains the flow rate by calculating the difference in frequency between the excitation signal sa and the detection signal Sr2, or the Doppler shift m, using a known method.

このような構成の流」計によれば、式（３）が示すよう
にドツプラーシフトｍｆｄには音速Ｃの項がふくまれず
、従って流体の音速の影響を受（Ｊないという利点があ
る。According to a flowmeter having such a configuration, the Doppler shift mfd does not include the term of the sound speed C, as shown in equation (3), and therefore has the advantage that it is not affected by the sound speed of the fluid.

また原理的に流体中の物体による反射を利用したもので
はないので均質媒体中の流量を測定できる。Furthermore, since it does not use reflection from objects in the fluid in principle, it is possible to measure the flow rate in a homogeneous medium.

なお上記の実施例では定゛在波を発生させる励振手段と
して圧電素子などの超音波トランデューサを用いたが、
任意の電磁機械的な励振手段を用いることも可能である
。Note that in the above embodiment, an ultrasonic transducer such as a piezoelectric element was used as the excitation means for generating a standing wave.
It is also possible to use any electromagnetic mechanical excitation means.

（発明の効果）以上述べたように本発明によれば均質媒体中の流量を測
定でき、流体の音速の影響を受けない、ドプラー効果を
利用した超音波流量計を実現することができる。(Effects of the Invention) As described above, according to the present invention, it is possible to realize an ultrasonic flowmeter that utilizes the Doppler effect and can measure the flow rate in a homogeneous medium and is not affected by the sound velocity of the fluid.

[Brief explanation of drawings]

図は本発明に係わる流ｍ計の一実施例の構成を示す構成
説明図である。The figure is a configuration explanatory diagram showing the configuration of an embodiment of a current meter according to the present invention.

Claims

[Claims]

an excitation means for generating a standing wave in a flow path, an ultrasonic detection means provided downstream or upstream of the excitation means, an excitation signal applied to the excitation means, and a detection output from the ultrasonic detection means. 1. A flowmeter comprising: calculation means for crushing the frequency difference between the signal and the signal.