JPH03186716A - Electromagnetic flowmeter - Google Patents
Electromagnetic flowmeterInfo
- Publication number
- JPH03186716A JPH03186716A JP32803089A JP32803089A JPH03186716A JP H03186716 A JPH03186716 A JP H03186716A JP 32803089 A JP32803089 A JP 32803089A JP 32803089 A JP32803089 A JP 32803089A JP H03186716 A JPH03186716 A JP H03186716A
- Authority
- JP
- Japan
- Prior art keywords
- dead
- signal
- detection
- measurement
- voltage
- 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
- 238000005259 measurement Methods 0.000 claims description 44
- 239000012530 fluid Substances 0.000 claims description 9
- 238000000034 method Methods 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 40
- 238000009736 wetting Methods 0.000 abstract 3
- 238000013459 approach Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 12
- 230000005284 excitation Effects 0.000 description 7
- 239000007788 liquid Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 2
Landscapes
- Measuring Volume Flow (AREA)
Abstract
Description
【発明の詳細な説明】
〈産業上の利用分野〉
本発明は、導管の中の測定流体が空になったときにこれ
を検知する電磁流量計に係り、特に各測定電極の接液抵
抗が共に大きくなっても全検知ができない領域が存在し
ないように改良された電磁流量計に関する。[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electromagnetic flowmeter that detects when a measuring fluid in a conduit is empty, and particularly relates to an electromagnetic flowmeter that detects when a measuring fluid in a conduit is empty. This invention relates to an electromagnetic flowmeter that has been improved so that there is no area in which complete detection cannot be performed even if the flowmeter becomes larger.
〈従来の技術〉
第5図は全検知機能を持つ従来の電磁流量計の構成を示
すブロック図である。<Prior Art> FIG. 5 is a block diagram showing the configuration of a conventional electromagnetic flowmeter having all detection functions.
10は内面が絶縁され測定流体Qを流すことの出来る導
管であり、この導管10には測定流体Qと接液する一対
の測定電極11a、llbが導管10とは絶縁されて固
定され、測定流体Qを接地する接液電極11cは接地点
Gに接続されている。Reference numeral 10 denotes a conduit whose inner surface is insulated and allows the measurement fluid Q to flow therein. A pair of measurement electrodes 11a and 11b which are in contact with the measurement fluid Q are fixed to this conduit 10 and are insulated from the conduit 10. The wetted electrode 11c that grounds Q is connected to the ground point G.
この測定流体Qに磁場を印加するためのwJ磁ココイル
12この導管10に近接して配置され、この励磁コイル
12には励磁回路13から励磁電流Ifが流されている
。A wJ magnetic cocoil 12 for applying a magnetic field to the measurement fluid Q is arranged close to the conduit 10, and an excitation current If is passed through the excitation coil 12 from an excitation circuit 13.
そして、これ等の導管10.励磁コイル12などにより
検出器14が構成されている。And these conduits 10. A detector 14 is configured by an excitation coil 12 and the like.
また、測定電極11a、11bには前置増幅器15が接
続されているが、この前置増幅器15は入力端が測定電
極11a、llbに接続されたバッファ増幅器15a、
15bとこれ等の出力端が入力端に接続された差動増幅
器15cとで構成されている。さらに、これ等の測定電
極11a、11bにはダイオードD + 、D 2のカ
ソードが接続されている。これ等のダイオードDI、D
2のアノードは負電源−■にそれぞれ接続され、ダイオ
ードD+ 、D2と負電源−■により定電流回路16
(16a、16b)が形成されている。Further, a preamplifier 15 is connected to the measurement electrodes 11a, 11b, and this preamplifier 15 includes a buffer amplifier 15a whose input end is connected to the measurement electrodes 11a, llb,
15b and a differential amplifier 15c whose output ends are connected to the input ends. Furthermore, the cathodes of diodes D + and D 2 are connected to these measurement electrodes 11a and 11b. These diodes DI, D
The anodes of 2 are connected to the negative power supply -■, respectively, and the constant current circuit 16 is connected by the diodes D+, D2 and the negative power supply -■.
(16a, 16b) are formed.
バッファ増幅器15bの出力端と共通電位点COMとの
間にはツェナダイオードI)ztとD22とが互いに逆
極性に直列に接続された直列回路が接続されている。A series circuit in which Zener diodes I)zt and D22 are connected in series with opposite polarities is connected between the output terminal of the buffer amplifier 15b and the common potential point COM.
差動増幅器15cの出力端は、信号処理回路17の入力
端に接続され、信号処理回路17はこの出力端に現れる
測定電圧VM+を用いて流量信号V(lを演算して出力
端18に出力する。The output end of the differential amplifier 15c is connected to the input end of the signal processing circuit 17, and the signal processing circuit 17 uses the measured voltage VM+ appearing at this output end to calculate the flow rate signal V(l) and outputs it to the output end 18. do.
また、全検知回路19は測定電圧v門1の内の測定th
極11a、llbに現れる直流電圧Ea、Ebの差に対
応する差電圧Ed+と基準電圧源20からの第1闇値電
圧VR+とを比較してその出力端21に全検知信号Ve
、を出力する。In addition, the entire detection circuit 19 is connected to the measurement voltage th of the measurement voltage V gate 1.
The difference voltage Ed+ corresponding to the difference between the DC voltages Ea and Eb appearing at the poles 11a and llb is compared with the first dark value voltage VR+ from the reference voltage source 20, and the entire detection signal Ve is outputted to the output terminal 21.
, outputs.
次に、以上のように構成された電磁流量計の動作につい
て説明する。Next, the operation of the electromagnetic flowmeter configured as above will be explained.
励磁回路13からは、例えば矩形波状の励磁電流Ifが
励磁コイル12に流され、これにより測定流体Qに矩形
波状の磁場が印加される。これに伴ない測定電極11a
、llbに発生する測定電圧は前置増幅器15でインピ
ーダンス変換されてその出力端に測定電圧vr’++
として出力される。For example, a rectangular-wave excitation current If is passed from the excitation circuit 13 to the excitation coil 12, thereby applying a rectangular-wave magnetic field to the measurement fluid Q. Along with this, the measurement electrode 11a
, llb is impedance-converted by the preamplifier 15, and the measured voltage vr'++ is output to the output terminal of the preamplifier 15.
is output as
次段の信号処理回路17はこの測定電圧VM1を用いて
流量演算をして出力端18に流量信号VQとして出力す
る。The signal processing circuit 17 at the next stage uses this measured voltage VM1 to calculate the flow rate and outputs it to the output terminal 18 as a flow rate signal VQ.
一方、測定電極11a、llbにはアノードが負電源−
■に接続されたダイオードD+ 、D2によってダイオ
ードの逆方向のリーク電流による定電流回路16が形成
されているので、検出器14が空になり測定電極11a
とllbとの間の接液抵抗Ra、Rhが大きくなると測
定電極11aと11bの直流電圧Ea、Bbが大きくな
る。On the other hand, the anodes of the measurement electrodes 11a and llb are connected to the negative power source.
Since the diodes D+ and D2 connected to
When the wetted resistances Ra and Rh between the electrodes 11a and 11b become larger, the DC voltages Ea and Bb of the measurement electrodes 11a and 11b become larger.
差動増幅器15cはこれ等の直流電圧Ea、Ebの差を
演算してその出力端に差電圧Ed+を出力する。全検知
回路19はこの差電圧Ed+が閾値電圧VR+を越える
と、導管10の中は空と判断してその出力端21に、例
えば負に振切れる全検知信号Ve+を出力する。The differential amplifier 15c calculates the difference between these DC voltages Ea and Eb and outputs a differential voltage Ed+ to its output terminal. When the differential voltage Ed+ exceeds the threshold voltage VR+, the total detection circuit 19 determines that the inside of the conduit 10 is empty and outputs, for example, a negative total detection signal Ve+ to its output terminal 21.
〈発明か解決しようとする課題〉
しかしながら、以上のような電磁流量計は、測定t 極
11 a、llbのいずれかが非接液になったときには
上記のように正常に動作するが、接液抵抗Ra−Rbが
共に大きくなったときには、差電圧IEaBblがほぼ
セロになり空になったにも拘らず全検知回路1つは空と
判断することができない。この様な場合に備えて第5図
に示す従来の電磁流量計ではバッファ増幅器15bの出
力端と共通電位点COMとの間にツェナダイオードD2
1 とD22を互いに逆極性で直列に接続して出力制限
をし、接液抵抗Ra、Rbが共に大きくなったときにも
バッファ増幅器15a、15bの出力に差が生じ−るよ
うにしている。<Invention or Problem to be Solved> However, the electromagnetic flowmeter as described above operates normally as described above when either the measurement pole 11a or llb is not in contact with liquid, but when it is in contact with liquid When the resistances Ra and Rb both become large, the differential voltage IEaBbl becomes almost zero, and even though the circuit is empty, one of the detection circuits cannot determine that it is empty. In preparation for such a case, in the conventional electromagnetic flowmeter shown in FIG. 5, a Zener diode D2 is connected between the output terminal of the buffer amplifier 15b and the common potential point COM.
1 and D22 are connected in series with opposite polarities to limit the output, so that even when both the wetted resistances Ra and Rb become large, a difference occurs between the outputs of the buffer amplifiers 15a and 15b.
しかしながら、この様な出力制限回路を設けても第6図
に示すように全検知回路19が空と判断できない領域が
生じる。However, even if such an output limiting circuit is provided, as shown in FIG. 6, there will be areas where all detection circuits 19 cannot be determined to be empty.
すなわち、第6図の横軸は接液抵抗Rhを、縦軸はRa
を、RはツェナタイオードDartとDi2による出力
のリミット電圧をそれぞれ示しているか、図の斜線で示
す領域では空検知をすることができない、特に、■接液
抵抗Rhが大きくなりEbの直流電位がツェナダイオー
ドD21とD22で制限されると接液抵抗R,が一定の
幅β1の範囲にあるときは空検知をすることができず、
また、■接液抵抗Ra、Rhか同時に大きくなるときの
空検知をすることができない領域が大きい、という問題
がある。That is, the horizontal axis in FIG. 6 represents the wetted resistance Rh, and the vertical axis represents Ra.
, R indicates the limit voltage of the output by the Zener diode Dart and Di2, respectively. Empty detection cannot be performed in the shaded area in the figure. In particular, ■ The wetted resistance Rh increases and the DC potential of Eb increases. is limited by Zener diodes D21 and D22, empty detection cannot be performed when the wetted resistance R is within a certain width β1,
In addition, there is a problem that (2) there is a large area in which empty detection cannot be performed when the liquid contact resistances Ra and Rh increase simultaneously.
く課題を解決するための手段〉
本発明は、以上のような課題を解決するために、測定流
体の中に発生した信号電圧を一対の測定電極で検出しこ
の信号電圧を信号処理手段で信号処理を実行して流量信
号として出力する電磁流量計において、測定電極に直流
の定電流を流す定電流手段と、測定電極間に発生した直
流電圧の差を求め第1閾値と比較して測定電極の非接液
状態を検知する差判定手段と、測定電極間に発生した直
流電圧の和を求め第2閾値と比較して測定電極の非接液
状態を検知する和判定手段と、差判定手段と和判定手段
の各出力の論理和を演算する演算手段とを具備し、この
演算手段の出力により測定電極の空状態を判定するよう
にしたものである。Means for Solving the Problems> In order to solve the above problems, the present invention detects a signal voltage generated in a measuring fluid with a pair of measurement electrodes, and converts this signal voltage into a signal using a signal processing means. In an electromagnetic flowmeter that performs processing and outputs it as a flow rate signal, the difference between the DC voltage generated between the constant current means that sends a constant DC current to the measuring electrode and the measuring electrode is calculated and compared with a first threshold value. a difference determining means for detecting a non-wetted state of the measuring electrode, a sum determining means for detecting a non-wetted state of the measuring electrode by calculating the sum of DC voltages generated between the measuring electrodes and comparing it with a second threshold value, and a difference determining means for detecting a non-wetted state of the measuring electrode. and calculation means for calculating the logical sum of each output of the sum determination means, and the empty state of the measurement electrode is determined based on the output of the calculation means.
く作 用〉
定電流手段により測定@極に直流の定電流を流し、差判
定手段によりこの測定電極間に発生した直流電圧の差と
第1閾値とを比較して測定電極の非接液状態を検知する
。Function: The constant current means passes a constant DC current to the measurement electrode, and the difference determination means compares the difference in DC voltage generated between the measurement electrodes with a first threshold value to determine the non-wetted state of the measurement electrodes. Detect.
さらに、和判定手段により測定電極間に発生した直流電
圧の和と第2閾値とを比較して測定電極の非接液状態を
検知する。Furthermore, the sum determination means compares the sum of the DC voltages generated between the measurement electrodes with a second threshold value to detect the non-wetted state of the measurement electrodes.
この後、演算手段により差判定手段と和判定手段の各出
力の論理和を演算してこの演算結果より測定流体が空に
なったか否かを判断する。Thereafter, the calculation means calculates the logical sum of the respective outputs of the difference determination means and the sum determination means, and it is determined from this calculation result whether or not the measured fluid is empty.
〈実施例〉
以下、本発明の実施例について図を用いて説明する。第
1図は本発明の1実施例の構成を示すブロック図である
。なお、第5図に示す従来の構成と同一の機能を有する
部分については同一の符号を付して適宜にその説明を省
略する。<Examples> Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. Note that parts having the same functions as those in the conventional configuration shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted as appropriate.
差動増幅器15cの出力端に発生する測定電極11a、
llbで測定された測定電圧の差に対応する測定電圧V
M2は信号処理回路17で信号処理がなされてその出力
端18に流量信号vQを出力する。A measurement electrode 11a generated at the output end of the differential amplifier 15c,
The measured voltage V corresponding to the difference in the measured voltages measured at llb
M2 undergoes signal processing in a signal processing circuit 17 and outputs a flow rate signal vQ to its output terminal 18.
一方、全検知回路19の一方の入力端にはこの測定電圧
v閂2が、他方の入力端には基1g、電圧源20からの
第1閾値電圧VR+がそれぞれ印加されているか、空検
知回F!!619は測定電圧VM2に含まれる直流の差
電圧Ed2と第1閾値電圧vRとを比較してその出力端
に全検知信号Ve2を出力する。On the other hand, this measurement voltage vbar2 is applied to one input terminal of the entire detection circuit 19, and the first threshold voltage VR+ from the voltage source 20 is applied to the other input terminal. F! ! 619 compares the DC difference voltage Ed2 included in the measurement voltage VM2 and the first threshold voltage vR, and outputs the entire detection signal Ve2 to its output terminal.
また、バッファ増幅器15aの出力に現れる測定電極1
1aで測定された測定電圧と、バッファ増幅器15bの
出力に現れる測定電極11bで測定された測定重圧とは
それぞれ抵抗R1とR2を介して加算増幅器22で加算
され、その出力端に測定電極11a、llbで測定され
た測定電圧の和に対めする測定電圧vM3が発生する。Also, the measurement electrode 1 appearing at the output of the buffer amplifier 15a
The measurement voltage measured at 1a and the measurement pressure measured at the measurement electrode 11b appearing at the output of the buffer amplifier 15b are added by a summing amplifier 22 via resistors R1 and R2, and the measurement electrode 11a, A measurement voltage vM3 is generated for the sum of the measurement voltages measured at llb.
全検知回路23の一方の入力端にはこの測定電圧V門3
が、他方の入力端には基準電圧源24からの第2閾Vi
”X圧VR2がそれぞれ印加されているが、全検知回路
23は測定電圧VM3に含まれる直流の和電圧Es2と
第2閾値電圧VR2とを比較してその出力端に全検知信
号Ve3を出力する。この場合、第2閾偵電圧VR2の
値は、第1閾値電圧VR+の3〜4倍程度に設定される
。This measurement voltage V gate 3 is connected to one input terminal of the entire detection circuit 23.
However, the second threshold Vi from the reference voltage source 24 is applied to the other input terminal.
``Although the X voltage VR2 is applied to each, the total detection circuit 23 compares the DC sum voltage Es2 included in the measurement voltage VM3 with the second threshold voltage VR2, and outputs the total detection signal Ve3 to its output terminal. In this case, the value of the second threshold voltage VR2 is set to about 3 to 4 times the first threshold voltage VR+.
25はORゲートであり、このORゲート25は全検知
信号Ve2とVe3の論理和を演算してその出力端26
に全検知信号Ve4として出力する。25 is an OR gate, and this OR gate 25 calculates the logical sum of all detection signals Ve2 and Ve3 and outputs the output terminal 26.
It is outputted as a total detection signal Ve4.
次に、以上のように構成された実施例の空検知の動作に
ついて第2図に示す特性図を用いて説明する。Next, the sky detection operation of the embodiment configured as above will be explained using the characteristic diagram shown in FIG. 2.
第2図の横軸は測定電極11bの接液抵抗Rbを、縦軸
は測定を極11aの接液抵抗11aを示す。βは第1閾
値電圧VR+、δは第2閾値電圧VR2と関連して定ま
る値である。The horizontal axis in FIG. 2 shows the liquid contact resistance Rb of the measurement electrode 11b, and the vertical axis shows the liquid contact resistance 11a of the measurement electrode 11a. β is a value determined in relation to the first threshold voltage VR+, and δ is a value determined in relation to the second threshold voltage VR2.
空検知回#119の出力に得られる差電圧Bd2に関連
する全検知信号■e2によって空検知ができる領域は、
横線によって囲まれた領域であるが、この場合、接液抵
抗RaとRbとの値の差が第1閾値電圧士VR+の幅の
中に入る不感帯β2の中にあるときはこの全検知信号v
e2により空か否かの判断ができない。The area where empty detection can be performed using the total detection signal ■e2 related to the differential voltage Bd2 obtained from the output of empty detection time #119 is as follows:
In this case, when the difference between the values of the wetted resistances Ra and Rb is within the dead zone β2 within the width of the first threshold voltage VR+, the entire detection signal v
It is not possible to determine whether it is empty or not based on e2.
しかし、全検知回路23の出力に得られる和電圧ES3
に関連する全検知信号ve3を用いるときは縦線によっ
て囲まれる領域も空検知をすることができる。However, the sum voltage ES3 obtained at the output of all detection circuits 23
When using the total detection signal ve3 related to , the area surrounded by the vertical line can also be sky-detected.
そこで、ORゲート25でこれ等の全検知信号Ve2と
Ve3の論理和を演算して全検知信号Ve4として出力
するようにしてこの全検知信号Ve4により、δ1とδ
2を結ぶ直線で示す境界より大きな接液抵抗の部分の空
検出をしてこの領域の不感帯β2の部分を除去する。Therefore, the OR gate 25 calculates the logical sum of these all detection signals Ve2 and Ve3 and outputs it as an all detection signal Ve4.
2, and the dead zone β2 in this region is removed.
つまり、導管10の中が空になり接液抵抗Ra、Rbの
いずれもが大きくなった全ての場合について空検知をす
ることができる。In other words, the empty state can be detected in all cases where the inside of the conduit 10 is empty and both the liquid contact resistances Ra and Rb become large.
第3図は本発明の他の実施例の構成の要部を示すブロッ
ク図である。この実施例はマイクロプロセッサを用いた
ときの構成である。FIG. 3 is a block diagram showing the main parts of the configuration of another embodiment of the present invention. This embodiment is a configuration using a microprocessor.
差動増幅器15cの出力端に現れている差の測定電圧V
M2と加算増幅器22の出力端に現れている和の測定電
圧VM3とはそれぞれ切換スイッチSW、の切換端に印
加され、その共通切換端からアナログ/デジタル変換器
27に切換信号が出力される。The measurement voltage V of the difference appearing at the output terminal of the differential amplifier 15c
M2 and the sum measurement voltage VM3 appearing at the output of the summing amplifier 22 are applied to the switching terminals of a changeover switch SW, respectively, and a switching signal is outputted to the analog/digital converter 27 from their common switching terminal.
アナログ/デジタル変換器27で測定電圧vM2とVM
2とはデジタル信号に変換され、マイクロプロセッサ2
8に出力される。マイクロプロセッサ28のメモリには
、第1閾値電圧VR+と第1r&値電圧VR2に対応す
るデータがそれぞれ格納されており、また、これ等のデ
ータを用いて空検知をする全検知回路19.23に対応
する演算およびORゲート25に対応する演算を実行す
る空検知プログラムも格納されている。そして、マイク
ロプロセッサ28はこの空検知プログラムにしたがって
これ等のデータを用いて全検知演算を実行して出力@2
6に空検知信号を出力する。流量信号についても同様に
演算して出力@18に流量信号Vcを出力する。The voltages vM2 and VM measured by the analog/digital converter 27
2 is converted into a digital signal and processed by the microprocessor 2.
8 is output. The memory of the microprocessor 28 stores data corresponding to the first threshold voltage VR+ and the first r&value voltage VR2, and all detection circuits 19 and 23 that use these data to perform empty detection. An empty detection program that executes the corresponding calculation and the calculation corresponding to the OR gate 25 is also stored. Then, the microprocessor 28 executes all detection calculations using these data according to this sky detection program and outputs @2.
An empty detection signal is output to 6. The flow rate signal is similarly calculated and the flow rate signal Vc is outputted at the output @18.
さらに、マイクロプロセッサ28は切換信号S、をスイ
ッチSW、に送出し、このスイッチSW1の切換を制御
する。Furthermore, the microprocessor 28 sends a switching signal S, to the switch SW, to control switching of the switch SW1.
第4図は本発明の他の実施例の要部の構成を示すプロ・
yり図である。FIG. 4 is a professional diagram showing the configuration of the main parts of another embodiment of the present invention.
It is a y diagram.
この場合は、バッファ増幅器15a、15bの出力をス
イッチSW1で切り換えてアナログ/デジタル変換器2
7に出力し、これをデジタル信号に変換し、マイクロプ
ロセッサ19に出力するようにしたものである。従って
、バッファ増幅器15a、15bの出力の差をとる演算
、和をとる演算、つまり差動増幅器15c、加算増幅器
22の機能をもマイクロプロセッサで実現するようにし
たものである。この場合も、スイッチSW、を切り換え
る切換信号S2はマイクロプロセッサ29により送出さ
れる。In this case, the outputs of the buffer amplifiers 15a and 15b are switched by the switch SW1, and the analog/digital converter 2
7, which is converted into a digital signal and output to the microprocessor 19. Therefore, the functions of the differential amplifier 15c and the summing amplifier 22 are also realized by the microprocessor. In this case as well, the switching signal S2 for switching the switch SW is sent out by the microprocessor 29.
〈発明の効果〉
以上、実線例と共に具体的に説明したように本発明は、
各測定@極に発生した直流電圧の和と差とをそれぞれ演
算し、それぞれ閾値と比較して検出した空検知信号の論
理和を用いて空検知をするようにしたので、各測定電極
の接液抵抗が共に大きくなりかつこれ等の値が接近して
いるときでも容易に空検知をすることかできる。<Effects of the Invention> As specifically explained above with the solid line example, the present invention has the following effects:
The sum and difference of the DC voltages generated at each measurement @pole are calculated, and compared with the respective threshold values, and the empty detection is performed using the logical sum of the detected empty detection signals, so the connection between each measurement electrode is Empty detection can be easily performed even when both liquid resistances are large and these values are close to each other.
第1図は本発明の1実施例の構成を示すブロック図、第
2図は第1図に示す実施例の動作を説明する特性図、第
3図は本発明の他の実施例の要部を示すブロック図、第
4図は本発明のさらに他の実施例の要部を示すブロック
図、第5図は従来の電磁流量計の構成を示すブロック図
、第6図は第5図に示す電磁流量計の動作を説明する特
性図である。
10−・・導管、lla、1 l b ・・・測定電極
、11C・・・接液電極、14・・・検出器、116a
、16 b−・・定電流回路、1路、19.23・・・
全検知回路、2
電圧源、22・・・加算増幅器、vR
圧、VR2・・・第2閾値電圧。
5・・・前置増幅器、
7・・・信号処理図
0.21・・・基準
、・・・第1閾値電FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention, FIG. 2 is a characteristic diagram explaining the operation of the embodiment shown in FIG. 1, and FIG. 3 is a main part of another embodiment of the present invention. FIG. 4 is a block diagram showing the main parts of still another embodiment of the present invention, FIG. 5 is a block diagram showing the configuration of a conventional electromagnetic flowmeter, and FIG. 6 is shown in FIG. FIG. 3 is a characteristic diagram illustrating the operation of an electromagnetic flowmeter. 10- Conduit, lla, 1 l b... Measuring electrode, 11C... Wetted electrode, 14... Detector, 116a
, 16 b-- Constant current circuit, 1 path, 19.23...
All detection circuits, 2 voltage source, 22... summing amplifier, vR pressure, VR2... second threshold voltage. 5... Preamplifier, 7... Signal processing diagram 0.21... Reference,... First threshold voltage
Claims (1)
出しこの信号電圧を信号処理手段で信号処理を実行して
流量信号として出力する電磁流量計において、前記測定
電極に直流の定電流を流す定電流手段と、前記測定電極
間に発生した直流電圧の差を求め第1閾値と比較して前
記測定電極の非接液状態を検知する差判定手段と、前記
測定電極間に発生した直流電圧の和を求め第2閾値と比
較して前記測定電極の非接液状態を検知する和判定手段
と、前記差判定手段と前記和判定手段の各出力の論理和
を演算する演算手段とを具備し、この演算手段の出力に
より前記測定電極の空状態を判定することを特徴とする
電磁流量計。In an electromagnetic flowmeter that detects a signal voltage generated in a measuring fluid with a pair of measuring electrodes, processes this signal voltage with a signal processing means, and outputs it as a flow rate signal, a constant DC current is applied to the measuring electrodes. a constant current means for causing a constant current to flow; a difference determining means for determining a difference in the DC voltage generated between the measurement electrodes and comparing it with a first threshold value to detect a non-wetted state of the measurement electrode; and a DC voltage generated between the measurement electrodes. a sum determining means for calculating a sum of voltages and comparing it with a second threshold value to detect a non-wetted state of the measurement electrode; and an arithmetic means for calculating a logical sum of each output of the difference determining means and the sum determining means. An electromagnetic flowmeter characterized in that the empty state of the measurement electrode is determined based on the output of the calculation means.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32803089A JP2691936B2 (en) | 1989-12-18 | 1989-12-18 | Electromagnetic flow meter |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32803089A JP2691936B2 (en) | 1989-12-18 | 1989-12-18 | Electromagnetic flow meter |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH03186716A true JPH03186716A (en) | 1991-08-14 |
JP2691936B2 JP2691936B2 (en) | 1997-12-17 |
Family
ID=18205734
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP32803089A Expired - Fee Related JP2691936B2 (en) | 1989-12-18 | 1989-12-18 | Electromagnetic flow meter |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2691936B2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2259028A2 (en) | 2009-05-28 | 2010-12-08 | Yokogawa Electric Corporation | Electromagnetic Flow Meter |
CN114341753A (en) * | 2019-08-29 | 2022-04-12 | 安赛乐米塔尔公司 | Edge pile-up measurement |
-
1989
- 1989-12-18 JP JP32803089A patent/JP2691936B2/en not_active Expired - Fee Related
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2259028A2 (en) | 2009-05-28 | 2010-12-08 | Yokogawa Electric Corporation | Electromagnetic Flow Meter |
US8433527B2 (en) | 2009-05-28 | 2013-04-30 | Yokogawa Electric Corporation | Electromagnetic flow meter |
CN114341753A (en) * | 2019-08-29 | 2022-04-12 | 安赛乐米塔尔公司 | Edge pile-up measurement |
CN114341753B (en) * | 2019-08-29 | 2024-03-08 | 安赛乐米塔尔公司 | Edge pile-up measurement |
Also Published As
Publication number | Publication date |
---|---|
JP2691936B2 (en) | 1997-12-17 |
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