JPS6326731Y2 - - Google Patents
Info
- Publication number
- JPS6326731Y2 JPS6326731Y2 JP1977115530U JP11553077U JPS6326731Y2 JP S6326731 Y2 JPS6326731 Y2 JP S6326731Y2 JP 1977115530 U JP1977115530 U JP 1977115530U JP 11553077 U JP11553077 U JP 11553077U JP S6326731 Y2 JPS6326731 Y2 JP S6326731Y2
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- fluid
- flow rate
- vortex
- ultrasonic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000012530 fluid Substances 0.000 claims description 22
- 230000001902 propagating effect Effects 0.000 claims 1
- 230000010355 oscillation Effects 0.000 description 20
- 238000001514 detection method Methods 0.000 description 13
- 238000005259 measurement Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
Landscapes
- Measuring Volume Flow (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
Description
【考案の詳細な説明】
本考案は超音波を利用して被測定流体の流量又
は流速を測定する装置に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring the flow rate or flow velocity of a fluid to be measured using ultrasonic waves.
周知の如く流体中に柱状渦発生体を挿入する
と、該渦発生体の両側面で流れが剥離し、該渦発
生体の下流側に交互に規則的な渦、即ちカルマン
渦が発生する。 As is well known, when a columnar vortex generator is inserted into a fluid, the flow separates on both sides of the vortex generator, and regular vortices, that is, Karman vortices, are generated alternately on the downstream side of the vortex generator.
該カルマン渦の生成数は流体の流速又は流量に
比例することからカルマン渦の検出により流量又
は流速を正確に測定出来る。 Since the number of Karman vortices generated is proportional to the flow rate or flow rate of the fluid, the flow rate or flow rate can be accurately measured by detecting the Karman vortices.
従来、一般的に実用化されている渦検出手段
は、渦発生体にサーミスタ等の熱的検出素子を配
設したり、渦発生体内或は渦発生体の後流側に設
置した検出体に圧力検出素子を配設したり、ある
いは、渦発生体内にボールやデイスク等の可動素
子を配設し、渦発生に伴う圧力差でボールやデイ
スク等の動きを電磁的に、又は光学的、その他の
手段により検出したりする方法がとられている。 Conventional vortex detection means that have been put into practical use include installing a thermal detection element such as a thermistor in the vortex generator, or installing a thermal detection element such as a thermistor in the vortex generator or a detection element installed within the vortex generator or on the downstream side of the vortex generator. A pressure detection element may be installed, or a movable element such as a ball or disk may be placed inside the vortex generator, and the movement of the ball or disk may be detected electromagnetically, optically, or otherwise using the pressure difference caused by the vortex generation. Detection methods are used.
然しながら、上記在来の検出手段では、カルマ
ン渦流量計の最大の特徴である100:1以上の広
い流量計測可能範囲を十分且つ高精度でカバーす
る測定は不可能であり、又、応答性も悪いので、
更に広い温度範囲に適用せしめることが不可能で
あつた。 However, with the above-mentioned conventional detection means, it is impossible to measure a wide flow rate measurement range of 100:1 or more, which is the most important feature of the Karman vortex flowmeter, with sufficient and high accuracy, and the response is also poor. Because it's bad,
It was impossible to apply it to a wider temperature range.
上記の諸点をカバーする為、超音波の特性を生
かした超音波利用の流定装置も提案されてはいる
ものの、安定した検出が困難な事から測定誤差を
伴ない易く、更に装置自体が複雑化して汎用性を
欠除すると云う不都合な問題があり、実用に供せ
られていなかつた。 In order to cover the above points, ultrasonic flow rate devices that take advantage of the characteristics of ultrasonic waves have been proposed, but they are prone to measurement errors because stable detection is difficult, and the devices themselves are complicated. However, it has not been put into practical use due to the disadvantageous problem of being overly complex and lacking in versatility.
本考案は叙上の不都合な問題点に鑑み成された
ものであつて、持続的な超音波信号により流体中
に発生しているカルマン渦の生成数を検出し、そ
れによつて正確に被計測流体の流量又は流速が測
定出来る超音波を利用した流量又は流速測定装置
の提供を目的とするもので、具体的には流路を介
して送受波される超音波信号波が流体中に発生す
るカルマン渦によつて周波数変調されることを利
用し、超音波受波用振動子の出力を高利得増幅器
を介して送波振動子に正帰環させて超音波信号の
変調を増幅させると共に周波数復調器により単位
時間当たりのカルマン渦の数を検出し、流体の流
量又は流速を測定するようにした流量又は流速測
定装置の提供にある。 The present invention was developed in view of the above-mentioned disadvantages, and uses a continuous ultrasonic signal to detect the number of Karman vortices occurring in a fluid, thereby accurately measuring the number of Karman vortices. The purpose of this device is to provide a flow rate or flow rate measuring device that uses ultrasonic waves that can measure the flow rate or velocity of a fluid. Specifically, ultrasonic signal waves that are transmitted and received through a flow path are generated in a fluid. Utilizing the fact that the frequency is modulated by the Karman vortex, the output of the ultrasonic receiving transducer is sent back to the transmitting transducer via a high gain amplifier to amplify the modulation of the ultrasonic signal and increase the frequency. An object of the present invention is to provide a flow rate or flow velocity measuring device that measures the flow rate or flow velocity of a fluid by detecting the number of Karman vortices per unit time using a demodulator.
又、本考案の他の目的とする処は、受波用振動
子の固有振動数と共振する周波数の近傍で自励発
振を始める正帰環の条件を満足せしめ、一旦作動
後は持続的に超音波の励振が為され、且つ、カル
マン渦列に対応した検出信号が連続的に得られる
ようにした流量又は流速測定装置の提供にある。 Another objective of the present invention is to satisfy the condition of a positive feedback loop that starts self-excited oscillation in the vicinity of the frequency that resonates with the natural frequency of the wave receiving oscillator, and once activated, it continues to oscillate continuously. An object of the present invention is to provide a flow rate or flow rate measuring device that excites ultrasonic waves and continuously obtains detection signals corresponding to the Karman vortex street.
以下に本考案の実施例を図面に基づき説明す
る。 Embodiments of the present invention will be described below based on the drawings.
図中符号1は被計測流体の流路で、流れに対し
垂直となるように周知の渦発生体2が挿入配設し
てある。該流路1の管壁には、渦発生体2より所
望距離後流側の処に超音波信号を発射する送波用
振動子3と、該送波用振動子3と対向して受波用
振動子4とを夫々配設してあつて、送波用振動子
3から発射された所望周波数の超音波信号波が流
路1を流れる流体を介して受波用振動子4の処迄
伝播するようにしてある。 Reference numeral 1 in the figure is a flow path for the fluid to be measured, and a well-known vortex generator 2 is inserted and arranged perpendicular to the flow. The pipe wall of the flow path 1 includes a wave transmitting transducer 3 that emits an ultrasonic signal to a desired distance downstream from the vortex generator 2, and a wave receiving transducer that faces the wave transmitting transducer 3. The ultrasonic signal wave of the desired frequency emitted from the transmitting transducer 3 reaches the receiving transducer 4 via the fluid flowing through the flow path 1. It is made to spread.
又、該受波用振動子4の出力部に、高利得増幅
器5を接続し、該高利得増幅器5の出力端を前記
送波用振動子3の入力部に接続すると共に周波数
復調器6にも接続してあり、又、該周波数復調器
の出力部には増幅器7を介して出力ターミナル8
を接続してある。 Further, a high gain amplifier 5 is connected to the output part of the wave receiving vibrator 4, and the output end of the high gain amplifier 5 is connected to the input part of the wave transmitting vibrator 3, and also connected to the frequency demodulator 6. is also connected to the output terminal of the frequency demodulator via an amplifier 7.
is connected.
上述の構成において、送波用振動子3が励振さ
れて該送波用振動子3の固有振動周波数の超音波
が発射されると、該超音波信号は流体中を伝播し
て受波用振動子4を励振せしめるが、この際、高
利得増幅器5の入出力間、即ち送波用振動子3
と、それによつて発射された流路1の中を伝播し
て受波用振動子4に到る超音波信号と、該超音波
信号を受波する受波用振動子4とで構成される帰
環路の位相が、正帰環の条件を満足するように発
振周波数を変化させて自動的に発振を持続する。 In the above configuration, when the transmitting transducer 3 is excited and an ultrasonic wave having a natural vibration frequency of the transmitting transducer 3 is emitted, the ultrasonic signal propagates through the fluid and becomes a receiving vibration. However, at this time, between the input and output of the high gain amplifier 5, that is, the transmitting oscillator 3
, an ultrasonic signal emitted thereby, which propagates through the channel 1 and reaches the receiving transducer 4, and a receiving transducer 4 that receives the ultrasonic signal. The oscillation frequency is changed so that the phase of the return path satisfies the condition of a positive return path, and oscillation is automatically maintained.
即ち、図面に示すように
送波用振動子3→流路内流体媒質
↑ ↓
高利得増幅器5←受波用振動子4
からなる自励発振ループにおいて、そのループゲ
インをGLとすると、発振を持続する条件は
GL<1
となることである。 That is, as shown in the drawing, in a self-excited oscillation loop consisting of the transmitting transducer 3 → fluid medium in the flow path ↑ ↓ high gain amplifier 5 ← receiving transducer 4, if the loop gain is G L , the oscillation The condition for maintaining is that G L <1.
上記自励発振ループのループゲインGLは高利
得増幅器5のゲインGAと、送波用振動子3のゲ
インGTと、受波用振動子4のゲインGRおよび送
波用振動子3および受波用振動子4間の流体伝播
ゲイン(損失)GFの和であらわされる。このル
ープゲインGLの周波数範囲が広い程、周波数の
大きい変化があつても発振を持続する。従つて、
本考案においては周波数範囲を決定する発振要素
である送波用振動子3、受波用振動子4の周波数
特性はQの低い方が有利である。 The loop gain G L of the self-excited oscillation loop is the gain G A of the high gain amplifier 5, the gain G T of the transmitting transducer 3, the gain G R of the receiving transducer 4, and the transmitting transducer 3. and fluid propagation gain (loss) G F between the wave receiving transducers 4. The wider the frequency range of this loop gain G L , the more the oscillation will continue even if there is a large change in frequency. Therefore,
In the present invention, it is advantageous for the frequency characteristics of the transmitting transducer 3 and the receiving transducer 4, which are oscillating elements that determine the frequency range, to have a lower Q.
ここで、流体の温度が変化すると超音波信号波
の周波数が変化するが、この自励発振系に於ける
発振周波数と温度の関係について説明する。 Here, when the temperature of the fluid changes, the frequency of the ultrasonic signal wave changes, and the relationship between the oscillation frequency and temperature in this self-oscillation system will be explained.
周波数は被測定流体の温度tによつて変化す
るが、
n:超音波送受波用振動子間に存在する波の数
(流体中)
C:音速(=C0+αt)
α:音速の温度係数
:超音波周波数(自励発振周波数)
λ:超音波の波長(流体中)
L:超音波送受波用振動子間の距離
t:温度差(基準温度に対する)
とすると
n=L/λ …
λ=C/ …
の関係がある。 The frequency changes depending on the temperature t of the fluid to be measured, and n: the number of waves existing between the ultrasonic wave transmitting and receiving transducers.
(in fluid) C: Speed of sound (=C 0 + αt) α: Temperature coefficient of sound speed: Ultrasonic frequency (self-excited oscillation frequency) λ: Wavelength of ultrasound (in fluid) L: Between transducers for ultrasonic wave transmission and reception If the distance t is the temperature difference (with respect to the reference temperature), then there is a relationship of n=L/λ...λ=C/....
,式より n=L/C 故に =(C0+αt)/L … が得られる。 , from the formula, n=L/C, so = (C 0 + αt)/L... can be obtained.
ここにおいて、自励発振系は増幅器が非反転型
である場合、超音波送受波用振動子間に整数個の
超音波の波を存在させるように発振周波数を自動
的に選択し、而かもその周波数は超音波送受波用
振動子の共振周波数の近傍値となる。 Here, when the amplifier is a non-inverting type, the self-excited oscillation system automatically selects the oscillation frequency so that an integral number of ultrasonic waves exist between the ultrasonic wave transmitting and receiving transducers, and The frequency is a value close to the resonant frequency of the ultrasonic wave transmitting/receiving transducer.
従つて上式のnは一定の値となり周波数は温
度tと共に変化し、温度変化に伴つて自動的に補
正されつつ自励発振が行われる。 Therefore, n in the above equation is a constant value, the frequency changes with the temperature t, and self-sustained oscillation is performed while being automatically corrected as the temperature changes.
正帰環発振を行う系において、上述のごとき発
振条件が成立するように発振周波数が自動的に変
化する現象は、例えば、マイクロホンが検出する
音声信号を増幅器にて電気的に増幅し、その信号
をスピーカに印加して音を大きくする系において
スピーカ → 空 気
↑ ↓
増幅器 ← マイクロホン
という閉ループが形成されたとき、この系が正帰
還発振を起こす現象、いわゆる“ハウリング”現
象に似ている。この“ハウリング”現象では、ス
ピーカとマイクロホンの距離が多少変化しても、
系のループゲインが1を超えている限り発振条件
が成立するような位相関係になるように発振周波
数が自動的に変化しても発振が持続される。本考
案の現象も、この“ハウリング”現象に似て居
り、しかも、この動作は位相を自動制御するため
の特別な装置の介在なしに、自然に行われるもの
である。 In a system that performs positive feedback oscillation, the phenomenon in which the oscillation frequency automatically changes so that the oscillation conditions as described above are satisfied is an example of the phenomenon in which an audio signal detected by a microphone is electrically amplified by an amplifier, and the signal is In a system that makes sound louder by applying it to a speaker, when a closed loop called speaker → air ↑ ↓ amplifier ← microphone is formed, this system causes positive feedback oscillation, a phenomenon similar to the so-called "howling" phenomenon. With this "howling" phenomenon, even if the distance between the speaker and microphone changes slightly,
As long as the loop gain of the system exceeds 1, oscillation is maintained even if the oscillation frequency is automatically changed so that the phase relationship is such that the oscillation conditions are satisfied. The phenomenon of the present invention is similar to this "howling" phenomenon, and moreover, this operation occurs naturally without the intervention of any special device for automatically controlling the phase.
前述した通り、渦発生体の後流側に流路を介し
て超音波送受波用振動子を対設した本考案の構成
における自励発振周波数は上記式のごとく、流
路内流体を伝播する超音波の音速Cに比例する。
従つて超音波伝播経路にカルマン渦が近接して通
過した場合、超音波伝播経路方向の渦の流れ成分
が、超音波の伝播速度Cに加減算される結果、自
励発振周波数はカルマン渦列により周波数変調を
受ける。変調周波数は単位時間当たりの渦の数に
比例するので、該変調周波数を復調することによ
り渦信号が検出され、単位時間当たりの渦の数に
比例した流速を算出することができる。本考案の
装置においては式に示したような流体の温度影
響を受けるが、一般に流体温度の変化は渦周波数
に対しては緩慢であり、無視することができるの
で、結果として温度に影響を受けることのない渦
検出ができる。 As mentioned above, the self-excited oscillation frequency in the configuration of the present invention, in which the ultrasonic wave transmitting/receiving transducer is disposed oppositely through the flow path on the downstream side of the vortex generator, propagates through the fluid in the flow path as shown in the above equation. It is proportional to the sound speed C of the ultrasonic wave.
Therefore, when a Karman vortex passes close to the ultrasonic propagation path, the flow component of the vortex in the direction of the ultrasonic propagation path is added to or subtracted from the ultrasonic propagation velocity C, and as a result, the self-oscillation frequency is increased by the Karman vortex street. Subject to frequency modulation. Since the modulation frequency is proportional to the number of vortices per unit time, a vortex signal is detected by demodulating the modulation frequency, and a flow velocity proportional to the number of vortices per unit time can be calculated. The device of this invention is affected by the temperature of the fluid as shown in the equation, but in general, the change in fluid temperature is slow relative to the vortex frequency and can be ignored, so as a result, it is not affected by the temperature. Easily detects vortices.
本考案によれば、超音波伝播経路内を通過する
乱流渦のようなカルマン渦に比例して極めて小さ
い雑音性の微小流れ成分は伝播経路内において平
均化され、これにより変調されることがないの
で、乱流渦の影響を受けないS/N比の優れた渦
検出が可能となる。また、サーミスタ検出方式の
ように検出素子が被測定流体に接しているとか、
渦発生体内にボールやデスク等の可動素子を配設
した従来の装置と比較して簡素化され、可動部を
持たない構造であるので、安定した渦の検出がで
き、応答性がよく、流量範囲の広い、堅牢で、低
廉な渦流量計が得られる。更にまた、簡易な構成
にも拘わらず、温度影響のない超音波検出式渦流
量計が得られる。 According to the present invention, noisy minute flow components, which are extremely small in proportion to Karman vortices such as turbulent vortices passing within the ultrasonic propagation path, are averaged within the propagation path and can be modulated by this. Therefore, it is possible to detect vortices with an excellent S/N ratio without being affected by turbulent eddies. In addition, when the detection element is in contact with the fluid to be measured, as in the thermistor detection method,
Compared to conventional devices that have movable elements such as balls and desks inside the vortex generator, it is simpler and has a structure that does not have any moving parts, allowing stable vortex detection, good responsiveness, and A robust, inexpensive vortex flowmeter with a wide range is obtained. Furthermore, an ultrasonic detection type vortex flowmeter that is not affected by temperature can be obtained despite its simple configuration.
図は本考案に係る流量又は流速測定装置のブロ
ツク図である。
1……流路、2……渦発生体、3……送波用振
動子、4……受波用振動子、5……高利得増幅
器、6……周波数復調器、7……増幅器、8……
出力ターミナル。
The figure is a block diagram of a flow rate or flow rate measuring device according to the present invention. DESCRIPTION OF SYMBOLS 1... Flow path, 2... Vortex generator, 3... Vibrator for transmitting waves, 4... Vibrator for receiving waves, 5... High gain amplifier, 6... Frequency demodulator, 7... Amplifier, 8...
Output terminal.
Claims (1)
流路を介して一対の超音波送受波用振動子を対設
し、該超音波受波用振動子間に高利得増幅器を接
続して閉ループを形成し、該閉ループをループゲ
インが1より大きい正帰還ループとして自励発振
させ、該自励発振周波数で流体中を伝播する超音
波を前記渦発生体の下流側に発生したカルマン渦
により周波数変調させ、該周波数変調信号から単
位時間当たりのカルマン渦の数を検出するように
したことを特徴とする流量又は流速測定装置。 A pair of ultrasonic wave transmitting/receiving transducers are provided oppositely through a flow path on the downstream side of the vortex generator inserted into the fluid to be measured, and a high gain amplifier is connected between the ultrasonic wave receiving transducers. to form a closed loop, self-oscillate the closed loop as a positive feedback loop with a loop gain greater than 1, and generate an ultrasonic wave propagating in the fluid at the self-oscillation frequency to generate a Karman vortex on the downstream side of the vortex generator. 1. A flow rate or flow rate measuring device characterized in that the frequency is modulated by the frequency modulated signal and the number of Karman vortices per unit time is detected from the frequency modulated signal.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1977115530U JPS6326731Y2 (en) | 1977-08-29 | 1977-08-29 |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1977115530U JPS6326731Y2 (en) | 1977-08-29 | 1977-08-29 |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5441664U JPS5441664U (en) | 1979-03-20 |
JPS6326731Y2 true JPS6326731Y2 (en) | 1988-07-20 |
Family
ID=29067244
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP1977115530U Expired JPS6326731Y2 (en) | 1977-08-29 | 1977-08-29 |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6326731Y2 (en) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS50109759A (en) * | 1974-02-05 | 1975-08-29 |
-
1977
- 1977-08-29 JP JP1977115530U patent/JPS6326731Y2/ja not_active Expired
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS50109759A (en) * | 1974-02-05 | 1975-08-29 |
Also Published As
Publication number | Publication date |
---|---|
JPS5441664U (en) | 1979-03-20 |
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