JPS635217A - Ultrasonic current meter - Google Patents
Ultrasonic current meterInfo
- Publication number
- JPS635217A JPS635217A JP61146823A JP14682386A JPS635217A JP S635217 A JPS635217 A JP S635217A JP 61146823 A JP61146823 A JP 61146823A JP 14682386 A JP14682386 A JP 14682386A JP S635217 A JPS635217 A JP S635217A
- Authority
- JP
- Japan
- Prior art keywords
- wave
- signal
- transmitting
- transmitted
- forward direction
- 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.)
- Granted
Links
- 230000005540 biological transmission Effects 0.000 claims abstract description 63
- 239000012530 fluid Substances 0.000 claims abstract description 23
- 230000010355 oscillation Effects 0.000 claims abstract description 18
- 230000000694 effects Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 9
- 238000005259 measurement Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 244000132059 Carica parviflora Species 0.000 description 1
- 235000014653 Carica parviflora Nutrition 0.000 description 1
- 244000201986 Cassia tora Species 0.000 description 1
- 241000083652 Osca Species 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- NCAIGTHBQTXTLR-UHFFFAOYSA-N phentermine hydrochloride Chemical compound [Cl-].CC(C)([NH3+])CC1=CC=CC=C1 NCAIGTHBQTXTLR-UHFFFAOYSA-N 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
Landscapes
- Measuring Volume Flow (AREA)
Abstract
Description
【発明の詳細な説明】
[産業上の利用分野コ
本発明は流体中に超音波を伝搬させ、送信および受信波
の位相差から流体の流速を測定する超音波流速計に関す
る。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic current meter that propagates ultrasonic waves in a fluid and measures the flow velocity of the fluid from the phase difference between transmitted and received waves.
[従来の技術]
従来、この種の超音波流速計としては、送波用トランス
デユーサより連続(又はバースト波)超音波を送波し、
流体中を伝搬し、受渡用トランスデユーサにより受波し
た波の、送波した波に対する位相差を求めて流体の流速
を測定するものがある。[Prior Art] Conventionally, this type of ultrasonic current meter transmits continuous (or burst wave) ultrasonic waves from a wave transmitting transducer,
There is a method that measures the flow velocity of a fluid by determining the phase difference between a wave propagated in a fluid and received by a transfer transducer with respect to a transmitted wave.
第6図は係る従来の超音波流速計のブロック図である。FIG. 6 is a block diagram of such a conventional ultrasonic current meter.
第6図において、TXは送信信号(電気信号)を出力す
る送信回路、1は矢印F方向に流体が流れている流管、
Pl及びP2はそれぞれ送信信号に対応する送信波T(
超音波)を送信し、送信波に対応する受信波Rを受信す
るトランスデユーサ、SLは送信波(受信波)を流体の
流れに沿う順方向又は流体の流れに逆らう逆方向に伝搬
させ、順方向の受信波R,及び逆方向の受信波Ruが得
られるようにトランスデユーサP1及びP2を切り替え
る順方向/逆方向切替器、RXは受信波Rに対応する受
信信号を受信する受信回路、CALは送信波Tと受信波
Rどの位相差に基づいて流体の流速を算出する演算器、
TIMは各部の動作を制御する信号を出力するタイマー
である。In FIG. 6, TX is a transmission circuit that outputs a transmission signal (electrical signal), 1 is a flow tube through which fluid flows in the direction of arrow F,
Pl and P2 are transmission waves T(
A transducer that transmits ultrasonic waves (ultrasonic waves) and receives received waves R corresponding to the transmitted waves, SL propagates the transmitted waves (received waves) in the forward direction along the fluid flow or in the reverse direction against the fluid flow, A forward/reverse switch that switches transducers P1 and P2 to obtain a forward received wave R and a reverse received wave Ru; RX is a receiving circuit that receives a received signal corresponding to the received wave R; , CAL is an arithmetic unit that calculates the fluid flow velocity based on the phase difference between the transmitted wave T and the received wave R;
TIM is a timer that outputs a signal that controls the operation of each part.
係る従来の超音波流速計において、送信波Tはトランス
デユーサP1とP2との取付間隔をL、流体の流速を■
、音速をC1超音波の角周波数をωとすると、
T= E、 sin (+1 t
(1)で表わされ、順方向の受信波Rd及び逆方向
の受信波Ruはそれぞれ、
Rd=E)、 sin ω(t−td) (
2)Ru=ERsinω ft −t u)
(3)で表わされる。ただし、t、及びtuは、し
t 、 = −(S)
C−■
である。従って、受信波R4と受信波R,との位相差Δ
φは、
Δφ=ω (tu td )
となる。第6式に示すように位相差Δφは2πを周期と
する周期関数である。位相差Δφの検出範囲は0〜2π
て、流速Vか大ぎくなると位相差Δφは、
△φ=2nyr+Δφ (7)となり
、別途nを検出することが必要になる。In such a conventional ultrasonic current meter, the transmitted wave T is determined by the mounting interval L between the transducers P1 and P2, and the fluid flow velocity by
, the sound speed is C1, and the angular frequency of the ultrasonic wave is ω, then T= E, sin (+1 t
(1), and the received wave Rd in the forward direction and the received wave Ru in the reverse direction are respectively Rd=E), sin ω(t-td) (
2) Ru=ERsinω ft −tu)
It is expressed as (3). However, t and tu are t, = -(S)C-■. Therefore, the phase difference Δ between the received wave R4 and the received wave R
φ becomes Δφ=ω (tu td ). As shown in Equation 6, the phase difference Δφ is a periodic function whose period is 2π. The detection range of phase difference Δφ is 0 to 2π
When the flow velocity V becomes large, the phase difference Δφ becomes Δφ=2nyr+Δφ (7), and it is necessary to separately detect n.
[発明が解決しようとする問題点]
ところで、上記構成の従来の超音波流速計は送信波Tと
受信波Rとの位相差か2π以上(実際はπ/2)に相当
する流速を測定することが困難であり、かつ測定値が音
速の影響を受けるという問題があった。[Problems to be Solved by the Invention] By the way, the conventional ultrasonic current meter with the above configuration measures a flow velocity corresponding to a phase difference of 2π or more (actually π/2) between the transmitted wave T and the received wave R. There was a problem in that it was difficult to measure, and the measured values were affected by the speed of sound.
なお、測定範囲を拡大するため、送信波Tを低周波で変
調する方式もあるが、回路が複R1tになってしまう。Note that in order to expand the measurement range, there is a method in which the transmitted wave T is modulated with a low frequency, but the circuit becomes multiple R1t.
本発明は上記問題点を解決するためになされたもので、
測定値が音速の影響を受けず、送信波Tと受信波Rどの
位相差が2π以上に相当する流速であっても、正確に流
速を測定できる超音波流速計を提供することを目的とす
る。The present invention has been made to solve the above problems,
It is an object of the present invention to provide an ultrasonic current meter that allows measurement values to be accurately measured without being influenced by the speed of sound, even when the phase difference between the transmitted wave T and the received wave R corresponds to 2π or more. .
[問題点を解決するための手段]
そこで、本発明では所定周波数の第1の発振信号に対応
する第1の送信信号及び第1の発振信号に近接する周波
数の第2の発振信号に対応する第2の送信信号を交互に
出力する送信回路と、所定方向に流体が流れている流管
に所定距離を隔てて配設され、それぞれ人力される送信
信号に対応する送信波を流管内に送信するとともに、そ
れぞれ送信波に対応する受信波を受信する第1のトラン
スデユーサ及び第2のトランスデユーサと、第1のトラ
ンスデユーサ及び第2のトランスデユーサか、それぞれ
第1の送信信号に対応する流体の流れに沿う順方向の第
1の送信波の送信、順方向の第1の送信波に対応する順
方向の第1の受信波の受信、第2の送信信号に対応する
順方向の第2の送信波の送信、順方向の第2の送信波に
対応する順方向の第2の受信波の受信、第1の送信信号
に対応する流体の流れに逆らう逆方向の第1の送信波の
送信、逆方向の第1の送信波に対応する逆方向の第1の
受信波の受信、第2の送信信号に対応する逆方向の第2
の送信波の送信及び逆方向の第2の送信波に対応する受
信波の受信を行なうように第1のトランスデユーサ及び
第2のトランスデユーサを交互に切り替えるトランスデ
ユーサ切替回路と、順方向の第1の送信波と順方向の第
1の受信波との位相差、逆方向の第1の送信波と逆方向
の第1の受信波との位相差、順方向の第2の送信波と順
方向の第2の受信波との位相差及び逆方向の第2の送信
波と逆方向の第2の受信波との位相差をそれぞれ算出す
る位相検出器と、各位相差に基づいて、流体の流速を算
出する演算器とから超音波流速計を構成する。[Means for solving the problem] Therefore, in the present invention, a first transmission signal corresponding to a first oscillation signal of a predetermined frequency and a second oscillation signal corresponding to a frequency close to the first oscillation signal are provided. A transmission circuit that alternately outputs a second transmission signal is arranged at a predetermined distance from a flow tube through which fluid is flowing in a predetermined direction, and each transmits a transmission wave corresponding to a human-powered transmission signal into the flow tube. At the same time, a first transducer and a second transducer each receive a received wave corresponding to a transmitted wave, and the first transducer and the second transducer each receive a first transmitted signal. Transmission of a first transmitted wave in a forward direction along the fluid flow corresponding to the first transmitted wave in the forward direction, reception of a first received wave in the forward direction corresponding to the first transmitted wave in the forward direction, and an order corresponding to a second transmitted signal. transmitting a second transmitted wave in the forward direction, receiving a second received wave in the forward direction corresponding to the second transmitted wave in the forward direction, and receiving a first wave in the reverse direction against the fluid flow corresponding to the first transmitted signal. transmission of a transmission wave in the opposite direction, reception of a first reception wave in the opposite direction corresponding to the first transmission wave in the opposite direction, and reception of a second reception wave in the opposite direction corresponding to the second transmission signal.
a transducer switching circuit that alternately switches a first transducer and a second transducer to transmit a transmitted wave and receive a received wave corresponding to a second transmitted wave in the opposite direction; The phase difference between the first transmitted wave in the direction and the first received wave in the forward direction, the phase difference between the first transmitted wave in the opposite direction and the first received wave in the opposite direction, and the second transmission in the forward direction a phase detector that calculates the phase difference between the wave and the second received wave in the forward direction, and the phase difference between the second transmitted wave in the opposite direction and the second received wave in the opposite direction; , and an arithmetic unit that calculates the flow velocity of the fluid, constitute an ultrasonic current meter.
[作 用]
上記構成の超音波流速計は、送信回路が第1の発振信号
に対応する第1の送信信号及び第1の発振信号に近接す
る周波数の第2の発振信号に対応する第2の送信信号を
交互に出力し、トランスデユーサ切替回路が第1のトラ
ンスデユーサ及び第2のトランスデユーサを交互に切り
替え、第1のトランスデユーサ及び第2のトランスデユ
ーサが第1の送信信号に対応する順方向の第1の送信波
の送信、順方向の第1の送信波に対応する順方向の第1
の受信波の受信、第2の送信信号に対応する順方向の第
2の送信波の送信、順方向の第2の送信波に対応する順
方向の第2の受信波の受信、第1の送信信号に対応する
逆方向の第1の送信波の送信、逆方向の第1の送信波に
対応する逆方向の第1の受信波の受信、第2の送信信号
に対応する逆方向の第2の送信波の送信、逆方向の第2
の送信波に対応する逆方向の第2の受信波の受信を行な
わせ、位相検出器が順方向の第1の送信波と順方向の第
1の受信波との位相差、逆方向の第1の送信波と逆方向
の第1の受信波との位相差、順方向の第2の送信波と;
噴方向の第2の受信波との位相差及領逆方向の第2の送
信波と逆方向の第2の受信波との位相差を算出し、演算
器が各位相差に基づいて、流体の流速を算出する。[Function] In the ultrasonic current meter having the above configuration, the transmission circuit transmits a first transmission signal corresponding to the first oscillation signal and a second oscillation signal corresponding to the second oscillation signal having a frequency close to the first oscillation signal. The transducer switching circuit alternately outputs the transmission signals of the first transducer and the second transducer, and the first transducer and the second transducer output the first transducer. Transmission of a first transmission wave in the forward direction corresponding to the transmission signal; first transmission wave in the forward direction corresponding to the first transmission wave in the forward direction;
reception of a received wave in the forward direction, transmission of a second forward transmission wave corresponding to the second transmission signal, reception of a second forward reception wave corresponding to the second transmission wave in the forward direction, reception of a second reception wave in the forward direction corresponding to the second transmission wave in the forward direction, Transmission of a first transmission wave in the opposite direction corresponding to the transmission signal, reception of a first reception wave in the opposite direction corresponding to the first transmission wave in the opposite direction, and reception of the first reception wave in the opposite direction corresponding to the second transmission signal. 2 transmission wave transmission, the second transmission wave in the opposite direction
A second received wave in the opposite direction corresponding to the transmitted wave is received, and the phase detector detects the phase difference between the first transmitted wave in the forward direction and the first received wave in the forward direction, and the second received wave in the opposite direction. The phase difference between the first transmitted wave and the first received wave in the opposite direction, and the second transmitted wave in the forward direction;
The phase difference with the second received wave in the injection direction and the phase difference between the second transmitted wave in the opposite direction and the second received wave in the opposite direction are calculated, and the calculation unit calculates the flow rate of the fluid based on each phase difference. Calculate the flow velocity.
[実施例]
以下、本発明の一実施例を添付図面を参照して詳細に説
明する。[Example] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.
第1図は本発明に係る超音波流速計のブロック図である
。第1図において、0SCAは周波数fAの発振信号Z
Aを常時出力しているA系発振器、05CBは周波数f
Aに近い周波数f、の発振信号2、を常時出力している
B系発振器、GA及びG、はそれぞれ発振信号ZA及び
発振信号Z8に対応するバースト信号を出力するA系ゲ
ート回路及びB系ゲート回路、TxA及びTX8はそれ
ぞれA系ゲート回路GA及びB系ゲート回路G、が出力
するバースト信号を増幅し、それぞれ送信信号TA及び
TIlを出力するA系送信回路及びB系送信回路、5W
2は送信信号TA及びT8並びに後述する受信信号RA
及びR8を交互に出力するA系/日系切替回路、Sl#
1は順方向/逆方向切替回路、1は矢印■方向に流体が
流れている流管、P、及びR2は流管1に距離りを隔て
て配設されたトランスデユーサ、RxA及びRX、はA
系受信回路及びB系受信回路、PDAはA系位相検出器
、PD、はB系位相検出器、SHAはA系位相検出器P
DAが出力する位相差に対応する信号をサンプリングし
てホールドするサンプルホールド回路、5HllはB系
位相検出器poaか出力する位相差に対応する信号をサ
ンプリングしてホールドするサンプルホールド回路、C
ALはサンプルホールド回路SHA及びSHBから入力
される位相差に基づいて、流体の流速Vを計算する演算
器、Iloは演算器CALの算出結果をアナログ指示す
るアナログ指示計又はデジタル表示するデジタル表示器
等に接続される入出力回路、TIMは全体の動作を制御
する順方向/逆方向切替信号X、、A系/B系切替信号
X2及び送信コントロール信号X、を発生するタイマー
であり、第1図には主要信号のみ指示しである。FIG. 1 is a block diagram of an ultrasonic current meter according to the present invention. In Fig. 1, 0SCA is the oscillation signal Z of frequency fA.
A system oscillator that constantly outputs A, 05CB has a frequency f
The B-system oscillators GA and G, which constantly output an oscillation signal 2 with a frequency f close to A, are an A-system gate circuit and a B-system gate that output burst signals corresponding to the oscillation signal ZA and the oscillation signal Z8, respectively. The circuits TxA and TX8 are an A-system transmitting circuit and a B-system transmitting circuit, 5W, which amplify the burst signals output by the A-system gate circuit GA and B-system gate circuit G, respectively, and output transmission signals TA and TIl, respectively.
2 is a transmission signal TA and T8 and a reception signal RA which will be described later.
A system/Japanese system switching circuit that alternately outputs R8 and R8, Sl#
1 is a forward/reverse direction switching circuit, 1 is a flow tube in which fluid flows in the direction of the arrow ■, P and R2 are transducers arranged at a distance in the flow tube 1, RxA and RX, is A
system receiving circuit and B system receiving circuit, PDA is A system phase detector, PD is B system phase detector, SHA is A system phase detector P
A sample and hold circuit samples and holds a signal corresponding to the phase difference outputted by the DA, 5Hll is a sample and hold circuit that samples and holds a signal corresponding to the phase difference outputted from the B-system phase detector poa, and C
AL is an arithmetic unit that calculates the fluid flow velocity V based on the phase difference input from the sample and hold circuits SHA and SHB, and Ilo is an analog indicator that gives an analog indication or a digital indicator that displays the calculation result of the arithmetic unit CAL. TIM is a timer that generates a forward/reverse switching signal X, an A/B switching signal X2, and a transmission control signal Only the main signals are shown in the figure.
次に、本発明に係る超音波流速計の動作について、第2
図のタイミングチャートを参照して説明する。まず、A
+ゲート回路GA及びB系ケート回路GI3は、それぞ
れ第2図(C)に示す周期T3の送信制御信号X3によ
り開閉動作し、それぞれA系発振器05CAの発振信号
ZA及びB系発振器O5C,の発振信号zBをサンプリ
ングし、バースト信号を出力する。A系ケート回路GA
及びB系ゲート回路G、の動作に同期して、A系/B系
切替回路SW2は第2図(b)に示す周期T2のA系/
B系切替信号信号x2により切り換えられ、第2図(d
)に示す送信信号TA及びT8を交互に出力する。Next, we will discuss the operation of the ultrasonic current meter according to the present invention in the second section.
This will be explained with reference to the timing chart shown in the figure. First, A
+Gate circuit GA and B-system gate circuit GI3 are opened and closed by the transmission control signal X3 with period T3 shown in FIG. The signal zB is sampled and a burst signal is output. A system gate circuit GA
In synchronization with the operation of the A-system/B-system gate circuit G and the B-system gate circuit G, the A-system/B-system switching circuit SW2 switches between the A-system/B-system gate circuits and the B-system gate circuit G with a cycle T2 shown in FIG. 2(b).
It is switched by the B-system switching signal x2, and as shown in FIG.
) The transmission signals TA and T8 shown in FIG.
次いで、順方向/逆方向切替回路SW、は第2図(a)
に示す周期T2の2倍の周期T1の順方向/逆方向切替
信号XIにより切り換えられる。A系/B系切替回路S
W2及び順方向/逆方向り替回路SW1の切り換工によ
り、トランスデユーサP1及びトランスデユーサP2は
以下に示す送信波の送信及び受信波の受信を行なう。第
1に1.順方向/逆方向切替回路SW、かD ’Jji
l C頭方向側)に、A系/B系切替回路SW2かA系
側にそれぞれ切り換えられると、トランスデユーサP1
はA系の送信信号TAに対応する順方向の送信波TAd
を送信1ノ、トランスデユーサP2はA系の順方向の受
信波RAdを受信する。第2に、順方向/逆方向切替回
路SW、がD側に、A系/B系切替回路SW2がB系側
にそれぞれ切り換えられると、トランスデユーサP1は
B系の送信信号T8に対応する;順方向の送信波TBd
を送信し、トランスデユーサP2はB系の順方向の受信
波RBdを受信する。第3に、順方向/逆方向切替回路
SW、がU側(逆方向側)に、A系/B系切替回路SW
2がA系側にそれぞれ切り換られると、トランスデユー
サP2はA系の送信信号TAに対応する逆方向の送信波
TAuを送信し、トランスデユーサP2はA系の逆方向
の受信波RAuを受信する。第4に、[順方向/逆方向
切替回路SW、がU側に、A系/B系切替回路SW2が
B系側にそれぞれ切り換られると、トランスデユーサP
2はB系の逆方向の送信波T、4を送信し、トランスデ
ユーサP1はB系の逆方向の受信波RBuを受信する。Next, the forward/reverse switching circuit SW is shown in FIG. 2(a).
Switching is performed by a forward/reverse direction switching signal XI having a cycle T1 that is twice the cycle T2 shown in FIG. A system/B system switching circuit S
By switching W2 and the forward/reverse switching circuit SW1, the transducer P1 and the transducer P2 perform the following transmission wave transmission and reception wave reception. Firstly 1. Forward/reverse switching circuit SW, or D'Jji
l C head direction side), A system/B system switching circuit SW2 or A system side is switched respectively, transducer P1
is the forward direction transmission wave TAd corresponding to the transmission signal TA of system A
The transducer P2 receives the A-system forward direction received wave RAd. Second, when the forward/reverse switching circuit SW is switched to the D side and the A system/B system switching circuit SW2 is switched to the B system side, the transducer P1 responds to the B system transmission signal T8. ;Forward transmission wave TBd
The transducer P2 receives the B-system forward direction reception wave RBd. Third, the forward direction/reverse direction switching circuit SW is placed on the U side (reverse direction side), and the A system/B system switching circuit SW is connected to the U side (reverse direction side).
2 are respectively switched to the A system side, transducer P2 transmits a transmission wave TAu in the opposite direction corresponding to the transmission signal TA of system A, and transducer P2 transmits a reception wave RAu in the opposite direction of system A. receive. Fourth, when the forward/reverse switching circuit SW is switched to the U side and the A/B switching circuit SW2 is switched to the B side, the transducer P
Transducer 2 transmits a transmission wave T, 4 in the opposite direction of the B system, and transducer P1 receives a reception wave RBu in the opposite direction of the B system.
ここで、A系の順方向の送信波TAd及び逆方向の送信
波TAu並びにB系の順方向の送信波T8.及び逆方向
の送信波T[luはそれぞれ、T Ad= T Au=
5in(2rt f A t ) (8)
Tad=Tau=sin(2gf、t) (
9)と表わせられる。又、A系の1項方向の受信波RA
d及び逆方向の受信波R,、u並びにB系の順方向の受
信波RBd及び逆方向の受信波RBuは距訓りを伝搬す
るのに必要な時間たけ遅れた位相になりそれぞれ、
=sin(2rt f 、 t −ΦAd)
flO)=sin(2rc f A t
−ΦAu) (11)=sin(2rt
f 、 を−Φad) (12)=sin
(2n f Bt −Φ[LLI)
(13)と表わせられる。ただし、Φ、4、ΦAi1
、Φ8.及びΦ8Uは、それぞれA系の順方向の位相差
1.へ系の逆方向の位相差、B系の順方向の位相差及び
B系の逆方向の位相差とする。Here, the forward direction transmission wave TAd and the reverse direction transmission wave TAu of the A system and the forward direction transmission wave T8 . and the reverse direction transmission wave T[lu are respectively T Ad= T Au=
5in(2rtfAt) (8)
Tad=Tau=sin(2gf,t) (
9). Also, the received wave RA in the 1st term direction of the A system
d and the backward received waves R,, u, and the forward received wave RBd and backward received wave RBu of system B have a phase delayed by the time required to propagate the distance signal, respectively, = sin (2rt f , t −ΦAd)
flO)=sin(2rc f A t
−ΦAu) (11)=sin(2rt
f, −Φad) (12)=sin
(2n f Bt −Φ[LLI)
It can be expressed as (13). However, Φ, 4, ΦAi1
,Φ8. and Φ8U are the forward phase difference of 1. A phase difference in the backward direction of the H system, a forward phase difference in the B system, and a phase difference in the reverse direction of the B system.
次いで、A系受信回路RX、はA系の順方向の受信波R
Ad及びA系の逆方向の受信波R81に対応する受信信
号RAを受信し、B系受信回路RX8はB系の順方向の
受信波R11d及びB系の逆方向の受信波RBuに対応
する受信信号R8を受信する。Next, the A-system receiving circuit RX receives the forward direction received wave R of the A-system.
The B-system receiving circuit RX8 receives the reception signal RA corresponding to Ad and the A-system backward reception wave R81, and the B-system reception circuit RX8 receives the reception signal RA corresponding to the B-system forward reception wave R11d and the B-system reverse reception wave RBu. Receive signal R8.
次いで、A系位相検出器PDAは送信波TAdと受信波
RAdどの位相差ΦAdに対応する信号及び送信波TA
LLと受信波RAuとの位相差ΦA、Jに対応する信号
を出力する。同様に、B系位相検出器PD、は送信波T
Bdと受信波Redとの位相差Φ3.に対応する信号及
び送信波Tauと受信波Rauどの位相差ΦBLIに対
応する信号を出力する。Next, the A-system phase detector PDA detects the signal corresponding to the phase difference ΦAd between the transmitted wave TAd and the received wave RAd and the transmitted wave TA.
A signal corresponding to the phase difference ΦA, J between LL and the received wave RAu is output. Similarly, the B-system phase detector PD, transmits the transmitted wave T
Phase difference Φ3 between Bd and received wave Red. , and a signal corresponding to the phase difference ΦBLI between the transmitted wave Tau and the received wave Rau.
次いで、サンプルホールド回路SHAはA系/B系切替
信号x2に制御され、A系位相検出器PDAが出力する
位相差Φ1及びΦ。に対応する信号をサンプリングして
ホールドする。又、サンプルホールド回路SOBはA系
/B系切替信号X2に制御され、B系位相検出器PDB
が出力する位相差Φ3゜及びΦBUに対応する信号をサ
ンプリングしてホールドする。サンプルホールド回路S
HA及び5l18はそれぞれ送信波の周期と同じ周期の
ランプ電圧を発生させ、これを受信波のゼロクロス点で
サンゴリングし、ホールドするものである。Next, the sample hold circuit SHA is controlled by the A system/B system switching signal x2, and the phase difference Φ1 and Φ output by the A system phase detector PDA. Sample and hold the signal corresponding to . In addition, the sample hold circuit SOB is controlled by the A system/B system switching signal X2, and the B system phase detector PDB
The signals corresponding to the phase difference Φ3° and ΦBU outputted by are sampled and held. Sample hold circuit S
The HA and 5l18 each generate a lamp voltage having the same period as the period of the transmitted wave, perform coral ringing at the zero-crossing point of the received wave, and hold it.
次いで、演算器CALは適宜のタイミング信号によりサ
ンプルホールド回路SHA及びSH!lから人力される
位相差ΦAd、ΦAu、Φ、d及びΦauに基づいて、
流体の流速■を計算する。Next, the arithmetic unit CAL uses the sample and hold circuits SHA and SH! by an appropriate timing signal. Based on the phase differences ΦAd, ΦAu, Φ, d and Φau manually input from l,
Calculate the fluid flow velocity ■.
ここで、A系の受信波RAdとRBdとの平均値R6及
びB系の受信波RAuとR11uとの平均値Ruは、
!
Rd=−(RAd+Rad)
ΦAd十Φ1id
=sin(π(f A + f a)t −)・cos
(rr(fA−f、)t−”’−”’) (14)R
u = (RAll” RBu)ΦAu+Φ、
U
=si口(π (f A +f 8)t −)Φ。Here, the average value R6 of the received waves RAd and RBd of the A system and the average value Ru of the received waves RAu and R11u of the B system are as follows. Rd=−(RAd+Rad) ΦAd×Φ1id = sin(π(f A + f a)t −)・cos
(rr(fA-f,)t-"'-"') (14)R
u = (RAll” RBu)ΦAu+Φ,
U = si (π (f A + f 8) t −) Φ.
−Φ。−Φ.
・cos(π(f A −f A) t −)
f15)である。又、A系の受信波の平均値R4の低
周波成分Rd及びB系の受信波の平均値Ruの低周波成
分Ruはそれぞれ、
ΦAd−ΦBd
R1=cos(π(f A −f a)t −)= c
os (2πfo を−Φdl (16)Φ
Au−ΦBu
Ru= CO3(π (fA−fa)t−)= cos
(2πfot−Φu) (17)となる。・cos(π(f A −f A) t −)
f15). In addition, the low frequency component Rd of the average value R4 of the received waves of the A system and the low frequency component Ru of the average value Ru of the received waves of the B system are respectively ΦAd - ΦBd R1 = cos (π (f A - f a) t −)=c
os (2πfo −Φdl (16)Φ
Au-ΦBu Ru= CO3(π (fA-fa)t-)= cos
(2πfot−Φu) (17).
ただし、
ΦAd−Φ、d
Φd = (18)
Φ。−ΦBu
Φ、 = (19)
fA−f。However, ΦAd−Φ, d Φd = (18)
Φ. −ΦBuΦ, = (19)
fA-f.
f0= (20)で
ある。なお、第16式の低周波成分Rd及び第17式の
低周波成分Ruは、第14式及び第15式の包結線であ
り、fo、Φ、及びΦ。はそれぞれ包絡線の周波数、順
方向の位相差の差及び逆方向の位相差の差である。f0=(20). Note that the low frequency component Rd of the 16th equation and the low frequency component Ru of the 17th equation are the encompassing lines of the 14th equation and the 15th equation, and are fo, Φ, and Φ. are the frequency of the envelope, the difference in forward phase difference, and the difference in phase difference in the reverse direction, respectively.
一方、A系発振器05CAの周波数fAとB系発振器O
SC,の周波数f、との差をとることは、ビート波の位
相を求めることに相当する。従って、A系発振器0SC
Aの周波数fAとB系発振器OSC,の周波数fBとを
近接して選べば、ビート波の周波数を他くすることがで
き、流速の広い範囲にわたって、
Φdく2π (21)及び
Φ5く2π (22)を保つこ
とができる。On the other hand, the frequency fA of the A-system oscillator 05CA and the B-system oscillator O
Taking the difference from the frequency f of SC, corresponds to finding the phase of the beat wave. Therefore, the A system oscillator 0SC
If the frequency fA of A and the frequency fB of the B-system oscillator OSC are selected close to each other, the frequency of the beat wave can be made different, and over a wide range of flow velocities, Φd × 2π (21) and Φ5 × 2π ( 22) can be maintained.
ここで、距1i1Lだけ隔てたときの波長λd、λ1と
位相差の差Φ1、Φ。どの関係は、L/λd:=:Φd
/2π (23)L/λ1=Φu/2π
(24)となる。又、音速Cと波長λ
d、λ、の関係は、λd = (c+V)/fo
(25)λ、= (C−V)/
fO(26)
となる。従って、第16式、第17式、第23式及び第
24式より、
Φd
L−λ、□
2π
Φ6.−Φ、d
” (C十V) (27)2
π (fA fa)
Φ。Here, the wavelengths λd, λ1 and the phase differences Φ1, Φ when separated by a distance 1i1L. Which relationship is L/λd:=:Φd
/2π (23)L/λ1=Φu/2π
(24). Also, the speed of sound C and the wavelength λ
The relationship between d and λ is λd = (c+V)/fo
(25)λ, = (CV)/
fO(26). Therefore, from Equations 16, 17, 23, and 24, Φd L−λ, □ 2π Φ6. -Φ,d” (C0V) (27)2
π (fA fa) Φ.
し=λ、□
2π
Φ^1−Φ8u
= (C−V) (28
)2π (fA−fa)
となる。shi=λ, □ 2π Φ^1−Φ8u = (C−V) (28
)2π (fA-fa).
演算器CALは第27式〜第28式から流速Vを、■=
πL(fA−fa)
により算出する。距ML及びA系発振器OS[:Aの周
波数fAとB系発振器O5(:!lの周波数fllとの
差(f A −f a) (
30)は定数であるので、演算器CALはA系の順方向
の位相差ΦAdとB系の順方向の位相差Φad(Φ1−
Φaa) (31)
及びA系の逆方向の位相差Φ。とB系の逆方向の位相差
Φh、
(Φ0−Φau) (32)
から流速■を算出することができるのである。Calculator CAL calculates the flow velocity V from the 27th to 28th equations, ■=
Calculated by πL(fA-fa). Distance ML and A-system oscillator OS [: Difference between frequency fA of A and frequency fll of B-system oscillator O5 (:!l (f A - f a) (
30) is a constant, the arithmetic unit CAL calculates the forward direction phase difference ΦAd of the A system and the forward direction phase difference Φad(Φ1−
Φaa) (31)
and the phase difference Φ in the opposite direction of the A system. and the phase difference in the opposite direction of the B system Φh, (Φ0−Φau) (32)
From this, the flow velocity ■ can be calculated.
流速Vは第29式に示すように音速に無関係である。従
って、A系発振器03CAの周波数fA及びB系発振器
OSC,の周波数f、を適当に選べば、A系の順方向の
位相差Φ。、A系の逆方向の位相差Φ。、B系の順方向
の位相差Φ、d及びB系の逆方向の位相差Φ、Uがそれ
ぞれ士rr−/ 2を超えても、1Φ□−Φ0,1くπ
/ 2 (33)及び
1Φ0−Φaul<π/ 2 (34)
を保つことが可能であり、広範囲にわたって流速■を測
定することができる。The flow velocity V is independent of the sound velocity as shown in Equation 29. Therefore, if the frequency fA of the A-system oscillator 03CA and the frequency f of the B-system oscillator OSC are appropriately selected, the forward phase difference Φ of the A system can be obtained. , the phase difference Φ in the opposite direction of the A system. , even if the forward phase difference Φ, d of system B and the reverse phase difference Φ, U of system B each exceed
/ 2 (33) and 1Φ0−Φaul<π/2 (34)
It is possible to maintain the flow rate and measure the flow rate over a wide range.
従来の超音波流速計では、超音波の周波数f=40KH
z 、音速C= 340m/S、トランスデユーサP1
とP2どの距211 L = 0.2m 、流速v =
tom/Sのとき、A系の順方向の位相差Φ6.は、
= 2.77π(rad )> 2 rt
(35)であった。しかし、本発明に係る超音
波流速計では、A系発振器05CAの発振周波数f A
= 4OK)Iz、B系発振器05Ctsの発振周波数
f、=40.4にHzのとき、A系の順方向の位相差Φ
Ad、 A系の逆方向の位相差Φ。、B系の順方向の位
相差ΦBd、B系の順方向の位相差Φ、はそれぞれ、
となり、
Φ□−ΦAd=2.78π (40
)Φ、U−ΦB、= 2.80π
(41)であるのに対し、
1ΦAd−Φaa l = 0.46πくπ/ 2
(42)1Φ□−Φaul=0.49πくπ/ 2
(43)になり、π/2以下となる。In the conventional ultrasonic current meter, the ultrasonic frequency f=40KH
z, sound speed C=340m/S, transducer P1
and P2 which distance 211 L = 0.2m, flow velocity v =
tom/S, the forward direction phase difference of the A system is Φ6. = 2.77π (rad) > 2 rt
(35). However, in the ultrasonic current meter according to the present invention, the oscillation frequency f A of the A-system oscillator 05CA
= 4OK) Iz, when the oscillation frequency f of the B system oscillator 05Cts is 40.4 Hz, the forward phase difference Φ of the A system
Ad, phase difference Φ in the opposite direction of the A system. , the forward direction phase difference ΦBd of the B system, and the forward direction phase difference Φ of the B system are, respectively, and Φ□−ΦAd=2.78π (40
) Φ, U-ΦB, = 2.80π
(41), whereas 1ΦAd−Φaa l = 0.46π×π/2
(42) 1Φ□−Φaul=0.49π×π/2
(43), which is less than π/2.
なお、流速Vに所定の係数を乗じて、流出を算出するよ
うにしてもよい。Note that the outflow may be calculated by multiplying the flow velocity V by a predetermined coefficient.
次いで、入出力回路I10は演算器CALの算出結果を
アナログ指示するアナログ指示計又はデジタル表示する
デジタル表示器等(図示せず)に出力する。Next, the input/output circuit I10 outputs the calculation result of the arithmetic unit CAL to an analog indicator that provides an analog instruction or a digital display that provides a digital display (not shown).
なお、順方向/逆方向切替回路SW、 、 A系/B系
切替回路SW2の切替えシーフェンスは順方向/逆方向
及びA系/B系が均等に切替えられれば、必ずしもこの
順序でなくとも良い。Note that the switching sea fences of the forward/reverse switching circuit SW, A system/B system switching circuit SW2 do not necessarily have to be in this order as long as the forward/reverse direction and the A system/B system are switched equally. .
次に、第3図は本発明に係る超音波流速計の他の実施例
を示すブロック図である。なお、第3図において、第1
図と同様の機能を果たす部分については同一の符号を付
し、その説明は省略する。Next, FIG. 3 is a block diagram showing another embodiment of the ultrasonic current meter according to the present invention. In addition, in Fig. 3, the first
Parts that perform the same functions as those in the figures are designated by the same reference numerals, and their explanations will be omitted.
本実施例では発振器05CA、 05C0、サンプルボ
ールド回28S1(A及び5llThを上記実施例と同
様に1組設けたが、ゲート回5!8G、送信回路TX、
受信回路RX、位相検出器PDを1個で構成した。これ
により、A系とB系とが共通に動作するので、構成要素
が少なくなるばかりか、A系、B系のそれぞれのハード
ウェアのもつ特性のバラツキ、ドリフトを補償すること
ができる。たたし、送信回路TX、受信回路R×は周波
数fA、faに対して同様に作動する必要性から、第1
図に示したものに比べて広帯域であるごとが要求される
。In this embodiment, one set of oscillators 05CA, 05C0, sample bold circuits 28S1 (A and 5llTh) are provided as in the above embodiment, but gate circuits 5!8G, transmission circuit TX,
The receiver circuit RX and phase detector PD are configured with one piece. As a result, the A system and the B system operate in common, which not only reduces the number of components, but also compensates for variations and drifts in the characteristics of the hardware of the A system and B system. However, since the transmitting circuit TX and the receiving circuit Rx need to operate in the same manner for the frequencies fA and fa, the first
A wider band than that shown in the figure is required.
次に、第4図及び第5図は本発明に係る超音波流速計の
他の実施例を示す主要部分のブロック図である。第4図
の実施例では、1組の発振器oscA、 osc、の代
わりに単一の発振器OSCを用い、タイマーTIMの信
号により分周器DIVの分周比を変えることにより周波
数fA、f6を発生させるものである。Next, FIGS. 4 and 5 are block diagrams of main parts showing other embodiments of the ultrasonic current meter according to the present invention. In the embodiment shown in FIG. 4, a single oscillator OSC is used instead of a set of oscillators oscA and osc, and frequencies fA and f6 are generated by changing the division ratio of the frequency divider DIV according to the signal of the timer TIM. It is something that makes you
又、第5図の実施例では、分周器DIVの代わりに電圧
可変周波数発振器VCO、位相比較器、フィルター及び
アンプを含むコントローラC0NT、カウンタCNTよ
りなるフニーズロツクルーブを用いたものである。In the embodiment shown in FIG. 5, a Funi's lock loop consisting of a voltage variable frequency oscillator VCO, a phase comparator, a controller C0NT including a filter and an amplifier, and a counter CNT is used in place of the frequency divider DIV.
上記実施例では、サンプルホールド回路を2組使用して
いるが、サンプリングホールド回路を4組使用し、A系
/B系、順方向/逆方向それぞれに対して専用として用
いることができる。又、全く1個のサンプルホールド回
路を交互に使用するようにすることもできる。In the above embodiment, two sets of sample and hold circuits are used, but four sets of sample and hold circuits can be used and used exclusively for each of the A system/B system and the forward direction/reverse direction. It is also possible to alternately use exactly one sample and hold circuit.
[発明の効果]
以上説明したように本発明によれば、順方向に送信され
る第1の周波数に対応する送信波と受信波との位相差Φ
Ad、逆方向に送信される第1の周波数に対応する送信
波と受信波との位相差ΦAu、順方向に送信される第1
の周波数に近接する第2の周波数に対応する送信波と受
信波との位相差Φ8.及び逆方向に送信される第2の周
波数に対応する送信波と受信波との位相差Φauに基き
、流体の流速■を、
V=izL (fA−fa )
により算出するようにしたので、音速の影響を受けずに
、流速を広範囲にわたって測定できる超音波流速計を得
ることができる。[Effects of the Invention] As explained above, according to the present invention, the phase difference Φ between the transmitted wave and the received wave corresponding to the first frequency transmitted in the forward direction
Ad, the phase difference ΦAu between the transmitted wave and the received wave corresponding to the first frequency transmitted in the reverse direction, the first frequency transmitted in the forward direction;
The phase difference between the transmitted wave and the received wave corresponding to a second frequency close to the frequency of Φ8. Based on the phase difference Φau between the transmitted wave and the received wave corresponding to the second frequency transmitted in the opposite direction, the fluid flow velocity ■ is calculated by V=izL (fA-fa), so the sound velocity It is possible to obtain an ultrasonic current meter that can measure flow velocity over a wide range without being affected by.
第1図は本発明に係る超音波流速計のブロック図、第2
図は第1図に示した超音波流速計の動作を示すタイミン
グチャート、第3図は本発明に係る超音波流速計の他の
実施例を示すブロック図、第4図及び第5図は本発明に
係る超音波流速計のは他の実施例を示す主要部分のブロ
ック図、第6図は従来の超音波流速計のブロック図であ
る。
各図中、05CA、 05Caは発振器、GA%G、は
ゲート回路、TXA、 TXaは送信回路、sw、は順
方向/逆方向切替回路、SW2はA系/B系切替回路、
1は流管、P、、P2はトランスデユーサ、RXA 、
Rxaは受信回路、PDA、 PD、は位相検出器、
SHA%SHaはサンプルホールド回路、CALは演算
器、TIMはタイマー、Iloは入出力回路である。
代理人 弁理士 佐 藤 正 年
第1図
TXA 、TXa : kit tiil k
SHA、SHB : ?”z7’llz;
l’;−ルト回路SWI : ++1員r3同/逆
万蘭>n皆回路ひL:、寅算猛SW2 :A禾/B尽防
9F回路 TIM・ クイマーI10.入出力回y
&
第4図 第5図
第6図Fig. 1 is a block diagram of an ultrasonic current meter according to the present invention, Fig. 2 is a block diagram of an ultrasonic current meter according to the present invention;
The figure is a timing chart showing the operation of the ultrasonic anemometer shown in Fig. 1, Fig. 3 is a block diagram showing another embodiment of the ultrasonic anemometer according to the present invention, and Figs. FIG. 6 is a block diagram of the main parts of another embodiment of the ultrasonic current meter according to the invention, and FIG. 6 is a block diagram of a conventional ultrasonic current meter. In each figure, 05CA and 05Ca are oscillators, GA%G is a gate circuit, TXA and TXa are transmitting circuits, sw is a forward/reverse switching circuit, SW2 is an A system/B system switching circuit,
1 is the flow tube, P2 is the transducer, RXA,
Rxa is a receiving circuit, PDA is a phase detector,
SHA%SHa is a sample hold circuit, CAL is an arithmetic unit, TIM is a timer, and Ilo is an input/output circuit. Agent Patent Attorney Tadashi Sato Figure 1 TXA, TXa: kit tiil k
SHA, SHB: ? ”z7'llz;
l';- Root circuit SWI: ++1 member r3 same/Gyakumaran>n all circuit HiL:, Tora calculation SW2: A/B 9F circuit TIM Kuimer I10. Input/output times
& Figure 4 Figure 5 Figure 6
Claims (1)
及び該第1の発振信号に近接する周波数の第2の発振信
号に対応する第2の送信信号を交互に出力する送信回路
と、所定方向に流体が流れている流管に所定距離を隔て
て配設され、それぞれ入力される送信信号に対応する送
信波を該流管内に送信するとともに、それぞれ該送信波
に対応する受信波を受信する第1のトランスデューサ及
び第2のトランスデューサと、前記第1のトランスデュ
ーサ及び前記第2のトランスデューサが、それぞれ前記
第1の送信信号に対応する前記流体の流れに沿う順方向
の第1の送信波の送信、該順方向の第1の送信波に対応
する順方向の第1の受信波の受信、前記第2の送信信号
に対応する該、順方向の第2の送信波の送信、該順方向
の第2の送信波に対応する該順方向の第2の受信波の受
信、該第1の送信信号に対応する該流体の流れに逆らう
逆方向の第1の送信波の送信、該逆方向の第1の送信波
に対応する該逆方向の第1の受信波の受信、該第2の送
信信号に対応する該逆方向の第2の送信波の送信及び該
逆方向の第2の送信波に対応する受信波の受信を行なう
ように該第1のトランスデューサ及び該第2のトランス
デューサを交互に切り替えるトランスデューサ切替回路
と、前記順方向の第1の送信波と前記順方向の第1の受
信波との位相差、前記逆方向の第1の送信波と前記逆方
向の第1の受信波との位相差、前記順方向の第2の送信
波と前記順方向の第2の受信波との位相差及び前記逆方
向の第2の送信波と前記逆方向の第2の受信波との位相
差をそれぞれ検出する位相検出器と、前記各位相差に基
づいて、前記流体の流速を算出する演算器とを備えたこ
とを特徴とする超音波流速計。a transmission circuit that alternately outputs a first transmission signal corresponding to a first oscillation signal of a predetermined frequency and a second transmission signal corresponding to a second oscillation signal of a frequency close to the first oscillation signal; They are arranged at a predetermined distance from each other in a flow tube through which fluid is flowing in a predetermined direction, and each transmits a transmission wave corresponding to an input transmission signal into the flow tube, and receives a reception wave corresponding to each transmission wave. A first transducer and a second transducer that receive a first transmitting wave in a forward direction along the flow of the fluid corresponding to the first transmitting signal, the first transducer and the second transducer respectively transmission, reception of a first received wave in the forward direction corresponding to the first transmitted wave in the forward direction, transmission of a second transmitted wave in the forward direction corresponding to the second transmitted signal, in the order receiving a second received wave in the forward direction corresponding to a second transmitted wave in the direction; transmitting a first transmitted wave in the opposite direction against the flow of the fluid corresponding to the first transmitted signal; receiving a first received wave in the opposite direction corresponding to the first transmitted wave in the opposite direction; transmitting a second transmitted wave in the opposite direction corresponding to the second transmitted signal; and transmitting a second transmitted wave in the opposite direction corresponding to the second transmitted signal. a transducer switching circuit that alternately switches the first transducer and the second transducer to receive a received wave corresponding to the transmitted wave; a phase difference between the received wave, a phase difference between the first transmitted wave in the opposite direction and the first received wave in the opposite direction, and a phase difference between the second transmitted wave in the forward direction and the second received wave in the forward direction. and a phase detector that detects the phase difference between the second transmitted wave in the opposite direction and the second received wave in the opposite direction, and calculates the flow velocity of the fluid based on each of the phase differences. An ultrasonic current meter characterized by comprising a computing unit that performs the following steps.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP61146823A JPS635217A (en) | 1986-06-25 | 1986-06-25 | Ultrasonic current meter |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP61146823A JPS635217A (en) | 1986-06-25 | 1986-06-25 | Ultrasonic current meter |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS635217A true JPS635217A (en) | 1988-01-11 |
JPH0569367B2 JPH0569367B2 (en) | 1993-09-30 |
Family
ID=15416333
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP61146823A Granted JPS635217A (en) | 1986-06-25 | 1986-06-25 | Ultrasonic current meter |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS635217A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001001081A1 (en) * | 1999-06-24 | 2001-01-04 | Matsushita Electric Industrial Co., Ltd. | Flowmeter |
-
1986
- 1986-06-25 JP JP61146823A patent/JPS635217A/en active Granted
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001001081A1 (en) * | 1999-06-24 | 2001-01-04 | Matsushita Electric Industrial Co., Ltd. | Flowmeter |
US6796189B1 (en) | 1999-06-24 | 2004-09-28 | Matsushita Electric Industrial Co., Ltd. | Ultrasonic flowmeter having sequentially changed driving method |
KR100487690B1 (en) * | 1999-06-24 | 2005-05-06 | 마쯔시다덴기산교 가부시키가이샤 | Flowmeter |
US6915704B2 (en) | 1999-06-24 | 2005-07-12 | Matsushita Electric Industrial Co., Ltd. | Ultrasonic flowmeter including stable flow rate calculation means based on instantaneous flow rate |
US6941821B2 (en) | 1999-06-24 | 2005-09-13 | Matsushita Electric Industrial Co., Ltd. | Ultrasonic flowmeter including stable flow rate calculation means based on instantaneous flow rate |
US7082841B2 (en) | 1999-06-24 | 2006-08-01 | Matsushita Electric Industrial Co., Ltd. | Ultrasonic flowmeter |
CN1293369C (en) * | 1999-06-24 | 2007-01-03 | 松下电器产业株式会社 | Flowmeter |
Also Published As
Publication number | Publication date |
---|---|
JPH0569367B2 (en) | 1993-09-30 |
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