JP2965242B2 - Mass flow meter converter - Google Patents
Mass flow meter converterInfo
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- JP2965242B2 JP2965242B2 JP10890195A JP10890195A JP2965242B2 JP 2965242 B2 JP2965242 B2 JP 2965242B2 JP 10890195 A JP10890195 A JP 10890195A JP 10890195 A JP10890195 A JP 10890195A JP 2965242 B2 JP2965242 B2 JP 2965242B2
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- frequency
- time difference
- reciprocal
- natural frequency
- flow tube
- Prior art date
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、質量流量計変換器に関
し、より詳細には、フローチューブを一定振幅の固有振
動で駆動したとき、フローチューブに作用するコリオリ
の力から質量流量を求め、固有振動数から流体の密度を
求めるコリオリ流量計のドリフトを補正する質量演算器
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mass flow meter converter, and more particularly, to a method for determining a mass flow rate from a Coriolis force acting on a flow tube when the flow tube is driven by a natural vibration having a constant amplitude. The present invention relates to a mass calculator for correcting a drift of a Coriolis flowmeter for obtaining a fluid density from a natural frequency.
【０００２】[0002]
【従来の技術】流体工業においては、流量計測は不可欠
であり、流量計測には目的に応じた各種流量計が使用さ
れる。従来、流量計としては、主に、容積流量計，オリ
フィス，渦流量計，電磁流量計等が用いられているが、
これらは体積流量計であり、求められた体積流量から質
量流量を求める場合は、密度，温度を補正する演算を施
す必要がある。このような方式では、密度，温度の検出
誤差を伴うものであり、例えば、高価な流体を扱うファ
インケミカル用としては、近年、直接質量をコリオリ流
量計が多く用いられるようになった。2. Description of the Related Art In the fluid industry, flow measurement is indispensable, and various kinds of flow meters according to the purpose are used for flow measurement. Conventionally, volumetric flowmeters, orifices, vortex flowmeters, electromagnetic flowmeters, and the like have been mainly used as flowmeters.
These are volume flow meters, and when calculating the mass flow rate from the obtained volume flow rate, it is necessary to perform an operation for correcting the density and the temperature. Such a method involves detection errors of density and temperature. For example, for fine chemicals that handle expensive fluids, a direct mass Coriolis flowmeter has recently been used in many cases.
【０００３】周知のように、コリオリ流量計は、被測流
体が流れるフローチューブを両端で支持し、支持された
測定管の中央部を支持線に直角な方向に交番駆動したと
き、フローチューブに質量流量に比例する位相差が生ず
ることを利用した質量流量計である。具体的には、フロ
ーチューブの両端支持部と中央部との間の対称位置に質
量流量に比例したコリオリの力による位相差信号を検出
し、位相差信号に比例した質量流量を求めるが、駆動周
波数を一定とすると、位相差信号は測定管の前記対称位
置におけるフローチューブが基準線を通過したときの時
間差信号として検出することができる。[0003] As is well known, a Coriolis flowmeter supports a flow tube through which a fluid to be measured flows at both ends, and when the central portion of the supported measurement tube is driven alternately in a direction perpendicular to the support line, the flow tube is connected to the flow tube. This is a mass flow meter utilizing the fact that a phase difference proportional to the mass flow rate occurs. Specifically, the phase difference signal due to the Coriolis force proportional to the mass flow rate is detected at a symmetrical position between the support portion and the center portion of the flow tube at both ends, and the mass flow rate proportional to the phase difference signal is obtained. Assuming that the frequency is constant, the phase difference signal can be detected as a time difference signal when the flow tube at the symmetric position of the measurement tube has passed the reference line.
【０００４】フローチューブを共振周波数で交番駆動さ
せ、フローチューブの寸法，材質，被測流体の密度に応
じた一定の駆動周波数が得られ、小さい駆動エネルギで
駆動することが可能となり、駆動周波数に応じた被測流
体の密度を求めることができることから、最近では測定
管を固有振動数で駆動するのが一般的となっている。[0004] The flow tube is driven alternately at a resonance frequency to obtain a constant drive frequency in accordance with the size, material, and density of the fluid to be measured. Since the density of the fluid to be measured can be determined according to the density, recently, it is common to drive the measuring tube at a natural frequency.
【０００５】図３は、従来の質量流量計変換器の構成を
説明するためのブロック図であり、図中、１はドライブ
回路、２は駆動コイル、３,４は検出コイル、５は位相
検出回路、６は全波整流回路、８はＣＰＵ（中央演算処
理装置）である。FIG. 3 is a block diagram for explaining the configuration of a conventional mass flowmeter converter. In FIG. 3, 1 is a drive circuit, 2 is a drive coil, 3, 4 is a detection coil, and 5 is a phase detection. The circuit, 6 is a full-wave rectifier circuit, and 8 is a CPU (Central Processing Unit).
【０００６】図３において、駆動部は、被測流体が流れ
る両端支持されたフローチューブ（図示せず）の中央部
に位置して支持体（図示せず）との間に取り付けられ、
例えば、駆動コイル２と、該駆動コイル２から磁気を受
けるコア（図示せず）等からなり、検出コイル３,４
は、フローチューブの支持部と駆動部との間の対称位置
で支持体との間に設けられ、例えば、検出コイル３,４
と磁石（図示せず）から構成される。In FIG. 3, the drive unit is located at the center of a flow tube (not shown) supported at both ends, through which a fluid to be measured flows, and attached between the flow tube and a support (not shown).
For example, the detection coils 3 and 4 include a drive coil 2 and a core (not shown) that receives magnetism from the drive coil 2.
Are provided between the support of the flow tube and the support at a symmetrical position between the support and the driving unit.
And a magnet (not shown).
【０００７】駆動コイル２は、ドライブ回路１の出力端
に接続され駆動されるが、ドライブ回路１の入力端に
は、検出コイル３で検出された正弦波信号を全波整流回
路６により整流した直流信号が接続され、検出コイル
３，全波整流回路６，ドライブ回路１，駆動コイル２か
らなる正帰還回路により、フローチューブ２の固有振動
数の正弦波発振回路が構成されている。このとき、検出
コイル３から出力されるＰ点での検出信号は、全波整流
回路６により直流電圧に変換され、ドライブ回路１にお
いて基準電圧と比較され、Ｐ点の正弦波信号ピーク電圧
が常に一定となるように制御されている。The drive coil 2 is connected to and driven by the output terminal of the drive circuit 1. The input terminal of the drive circuit 1 rectifies a sine wave signal detected by the detection coil 3 by a full-wave rectifier circuit 6. A DC signal is connected, and a positive feedback circuit including a detection coil 3, a full-wave rectifier circuit 6, a drive circuit 1, and a drive coil 2 forms a sine wave oscillation circuit having a natural frequency of the flow tube 2. At this time, the detection signal at point P output from the detection coil 3 is converted to a DC voltage by the full-wave rectifier circuit 6 and compared with the reference voltage in the drive circuit 1 so that the peak voltage of the sine wave signal at point P is always It is controlled to be constant.
【０００８】この結果、検出コイル４の検出電圧は、検
出コイル３の正弦波信号に対して、コリオリの力に比例
した位相差をもった一定振幅正弦波信号となり、位相差
は位相検出回路５により検出される。図４は、コリオリ
質量流量計の時間差測定の一例を説明するための図であ
る。図４（ａ）は、フローチューブの検出位置における
フローチューブの変位信号を示す図であり、検出された
正弦波信号を増幅整形して得られた台形波信号で、横軸
に時間、縦軸に電圧をとっている。図において台形ＡＢ
ＣＤ…および台形Ａ1Ｂ1Ｃ1Ｄ1…は時間軸Ｘ−Ｘに対し
電圧ピーク値の絶対値が等しく正負（±Ｅ）の電圧をも
った位相の異なるフローチューブの変位信号を示したも
ので、各々の変位信号は時間軸上連続した同形の台形波
形であり位相差時間をあらわす基準時間は、例えば、一
つの台形波形ＡＢＣＤの斜辺ＣＤのピーク値Ｃ（＋Ｅ）
あるいはＤ（−Ｅ）と、時間軸をクロスする位置Ｏとの
時間Ｔである。As a result, the detection voltage of the detection coil 4 becomes a constant amplitude sine wave signal having a phase difference proportional to the Coriolis force with respect to the sine wave signal of the detection coil 3. Is detected by FIG. 4 is a diagram for explaining an example of the time difference measurement of the Coriolis mass flow meter. FIG. 4A is a diagram showing a displacement signal of the flow tube at the detection position of the flow tube, which is a trapezoidal wave signal obtained by amplifying and shaping the detected sine wave signal. Voltage. In the figure, trapezoid AB
CD and trapezoids A 1 B 1 C 1 D 1 ... Indicate displacement signals of flow tubes having different positive and negative (± E) voltages with the same absolute value of the voltage peak value with respect to the time axis XX. Each of the displacement signals is a continuous trapezoidal waveform having the same shape on the time axis, and the reference time representing the phase difference time is, for example, a peak value C (+ E) of the hypotenuse CD of one trapezoidal waveform ABCD.
Alternatively, it is the time T between D (−E) and the position O crossing the time axis.
【０００９】位相の異なる前記台形ＡＢＣＤおよびＡ1
Ｂ1Ｃ1Ｄ1の変位信号において、例えば、辺ＣＤおよび
Ｃ1Ｄ1において位相差信号を説明する。四辺形ＣＣ1Ｄ1
Ｄ1は平行四辺形で、平行辺ＣＤとＣ1Ｄ1の時間差ΔＴ
は位相差信号であり、辺ＣＣ1ＤＤ1は時間軸ＯＯ1と等
しい長さを持っており、点Ｃ1およびＤ1から時間軸への
投影点を各々Ｏ2Ｏ3とすると辺Ｏ2Ｏは時間（Ｔ−Δ
Ｔ），辺ＯＯ3は時間（Ｔ＋ΔＴ）を示す。The trapezoids ABCD and A 1 having different phases.
In the displacement signal of B 1 C 1 D 1 , for example, a phase difference signal at the side CD and C 1 D 1 will be described. Quadrilateral CC 1 D 1
D 1 is a parallelogram, and the time difference ΔT between the parallel side CD and C 1 D 1
Is a phase difference signal, the side CC 1 DD 1 has a length equal to the time axis OO 1, and the projection points from the points C 1 and D 1 to the time axis are respectively O 2 O 3 and the side O 2 O is the time (T-Δ
T) and the side OO 3 indicate time (T + ΔT).
【００１０】時間（Ｔ−ΔＴ）は図４（ｃ）、時間（Ｔ
＋ΔＴ）は、図４（ｄ）に示すパルスで示され、時間差
ΔＴは、ＣＰＵ８において、図４（ｂ）に示す台形波一
周期の時間幅Ｍの時間パルスの２倍の時間２Ｍの間にお
ける各々のパルス幅の加算値を減算して平均を求めてい
る。例えば、 ｛４（Ｔ＋ΔＴ）−４（Ｔ−ΔＴ）｝／８＝ΔＴ …（１） により求められる。The time (T-ΔT) is shown in FIG.
+ ΔT) is indicated by the pulse shown in FIG. 4D, and the time difference ΔT is determined by the CPU 8 during the time 2M which is twice as long as the time pulse having the time width M of one cycle of the trapezoidal wave shown in FIG. An average is obtained by subtracting the added value of each pulse width. For example, {4 (T + ΔT) −4 (T−ΔT)} / 8 = ΔT (1)
【００１１】（１）式により求める時間差△Ｔは、誤差
が含まれていない理想条件での値である。例えば、図５
に示すように流量計測を開始するとき、流量零の状態で
は△Ｔ＝０でなければならないが、例えば、検出コイル
３,４の検出ゲインが正確に一致しないなどのため、△
Ｔ≠０であり、そのために計測する前に零点調整する必
要がある。しかし、零点調整が行われても時間経過にお
ける状態量の変化により零点が移動し、誤差要因とな
る。The time difference ΔT obtained by the equation (1) is a value under ideal conditions that does not include an error. For example, FIG.
When the flow rate measurement is started as shown in (1), ΔT must be zero in the state of zero flow rate. However, since the detection gains of the detection coils 3 and 4 do not exactly match, for example,
Since T ≠ 0, it is necessary to adjust the zero before measurement. However, even if the zero point adjustment is performed, the zero point moves due to a change in the state quantity over time, which causes an error.
【００１２】[0012]
【発明が解決しようとする課題】コリオリ流量計は、一
般の体積流量計と同様に、被測流体の種類，流量範囲，
温度，圧力条件等、各々異なる条件のもとでの流量計測
をしなければならない。フローチューブを共振駆動する
か固有振動数で駆動する方式のコリオリ流量計では、例
えば、被測流体の密度の相異によって振動周波数が異な
り、また、流量範囲により選ばれ、規格されたフローチ
ューブの口径，長さ等、幾何学形状の種類によっても振
動周波数が異なる。理想的なコリオリ流量計では、流体
密度が一定であり、これに伴って定められるフローチュ
ーブの固有振動数が一定であれば、計測される時間差△
Ｔが定まり、時間差△Ｔに比例した質量流量も一定に検
出できる。しかし、実際には、固有振動数が一定であっ
ても、時間差△Ｔは質量流量に比例せず、ドリフトが生
ずる。The Coriolis flow meter is, like a general volume flow meter, the type of the fluid to be measured, the flow rate range,
The flow rate must be measured under different conditions such as temperature and pressure conditions. In a Coriolis flowmeter of the type in which the flow tube is driven by resonance or driven by a natural frequency, for example, the vibration frequency differs depending on the density of the fluid to be measured, and the flow tube is selected and standardized according to the flow rate range. The vibration frequency also differs depending on the type of geometrical shape, such as diameter and length. In an ideal Coriolis flow meter, if the fluid density is constant and the natural frequency of the flow tube determined accordingly is constant, the measured time difference △
T is determined, and the mass flow rate proportional to the time difference ΔT can be detected constantly. However, in practice, even if the natural frequency is constant, the time difference ΔT is not proportional to the mass flow rate, and drift occurs.
【００１３】本発明は、ドリフトの大きさが振動周波数
に依存する値をもっていることから、ドリフト量と振動
周波数の関係に基づいて計測された時間差△Ｔに対し、
ドリフト量を補正し、理想に近い質量流量を求めること
を目的とする。According to the present invention, since the magnitude of the drift has a value dependent on the vibration frequency, the time difference ΔT measured based on the relationship between the drift amount and the vibration frequency is calculated as follows.
It is an object of the present invention to correct a drift amount and obtain a mass flow rate close to an ideal.
【００１４】[0014]
【課題を解決するための手段】本発明は、上記課題を解
決するために、被測定流体が流れるフローチューブを少
なくとも２点で支持し、該支持点まわりに一定振幅の固
有振動数で駆動したとき、該フローチューブに作用する
コリオリの力を位相差として検出し、位相差に比例した
時間差を計測して質量流量を求めるコリオリ流量計にお
いて、前記時間差を求める時間差計測手段と、前記固有
振動数を検出する周波数計測手段と、前記周波数計測手
段により検出された固有振動数の逆数を演算する逆数演
算手段とからなり、前記時間差計測手段により求められ
た時間差と前記逆数演算手段により演算された固有振動
数の逆数との差により零点ドリフト量を補正することを
特徴とする。According to the present invention, in order to solve the above-mentioned problems, a flow tube through which a fluid to be measured flows is supported at at least two points, and driven around the supporting point at a natural frequency having a constant amplitude. When the Coriolis force acting on the flow tube is detected as a phase difference, and a time difference proportional to the phase difference is measured to obtain a mass flow rate, the time difference measuring means for obtaining the time difference, and the natural frequency and frequency measuring means for detecting the frequency measurement hand
Reciprocal calculating means for calculating the reciprocal of the natural frequency detected by the step, which is obtained by the time difference measuring means.
Time difference and natural vibration calculated by the reciprocal calculating means
It is characterized in that the zero-point drift amount is corrected based on the difference from the reciprocal of the number .
【００１５】[0015]
【作用】フローチューブが一定振幅の固有振動で駆動さ
れるコリオリ流量計では、固有振動数が被測流体の密
度、およびフローチューブの幾何学形状によって変化
し、振動周波数に応じたドリフトが生ずる。ドリフト量
は振動周波数の逆数の関数であることが確められたの
で、このドリフト量を打消すため、振動周波数を検出し
てドリフト量と、振動周波数の関係からドリフト量を求
めて補正する。In a Coriolis flowmeter in which a flow tube is driven by natural vibration having a constant amplitude, the natural frequency changes depending on the density of the fluid to be measured and the geometry of the flow tube, and a drift occurs according to the vibration frequency. Since it has been confirmed that the drift amount is a function of the reciprocal of the vibration frequency, in order to cancel the drift amount, the vibration frequency is detected and the drift amount is obtained and corrected from the relationship between the drift amount and the vibration frequency.
【００１６】[0016]
【実施例】フローチューブの固有振動数が変化すること
により、コリオリの力に比例した時間差△Ｔにドリフト
が生ずるという現象に対して、本出願人は、時間差△Ｔ
のドリフト量Ｚｆと固有振動数ｆとの関係を調べた。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present applicant has proposed a method for solving the phenomenon that a time difference ΔT proportional to the Coriolis force causes a drift due to a change in the natural frequency of a flow tube.
The relationship between the drift amount Zf and the natural frequency f was examined.
【００１７】図１は、固有振動数と時間差△Ｔのドリフ
ト量との関係を説明するための実験結果を示した図であ
り、横軸が固有振動数ｆ、縦軸がドラフト量（時間）Ｚ
fである。FIG. 1 is a diagram showing experimental results for explaining the relationship between the natural frequency and the drift amount of the time difference ΔT, wherein the horizontal axis represents the natural frequency f and the vertical axis represents the draft amount (time). Z
f .
【００１８】図１に示す曲線は、固有振動数ｆが低周波
から高周波に向けて変化するとドリフト量Ｚfは漸時低
下し、その関係は、The curve shown in FIG. 1, the natural frequency f is changed toward the high frequency from the low frequency drift amount Z f decreases lozenges, that relationship is
【００１９】[0019]
【数１】 (Equation 1)
【００２０】であらわされることが確められた。It has been confirmed that
【００２１】この関係が発生する原因は、図３に示した
ドライブ回路１の入力信号の大きさが変化しても検出コ
イル３の正弦波信号のピーク値が一定に制御され、更
に、位相検出回路５では、一定振幅の正弦波検出信号を
増幅整形して得られた、図４に示した台形波信号ＡＢＣ
Ｄは、時間軸Ｘ−Ｘに対して一定電圧（±Ｅ）の高さを
もっているから、固有振動数が変化すると、斜辺ＡＢ，
ＣＤの傾斜角が変化するが、斜辺ＡＢ，ＣＤは、正しい
直線ではなく、近似直線であることによるものと推察で
きる。The reason why this relationship occurs is that the peak value of the sine wave signal of the detection coil 3 is controlled to be constant even if the magnitude of the input signal of the drive circuit 1 shown in FIG. In the circuit 5, a trapezoidal wave signal ABC shown in FIG.
Since D has a constant voltage (± E) with respect to the time axis XX, when the natural frequency changes, the hypotenuse AB,
Although the inclination angle of the CD changes, it can be inferred that the hypotenuses AB and CD are not straight lines but approximate lines.
【００２２】従って、たとえば図１に示したTherefore, for example, as shown in FIG.
【００２３】[0023]
【数２】 (Equation 2)
【００２４】曲線の定数Ｋ値は一定であり、この関係か
らドリフト量を補正することが可能となる。The constant K value of the curve is constant, and the drift amount can be corrected from this relationship.
【００２５】図２は、本発明による質量流量計変換器の
回路ブロックを説明するための図で、図中、１はドライ
ブ回路、２は駆動コイル、３,４は検出コイル、５は位
相検出回路、６は全波整流回路、７は周波数計、８はＣ
ＰＵ（中央演算処理装置）、９は周波数の逆数演算部で
（以後、逆数演算部と記す）である。FIG. 2 is a diagram for explaining a circuit block of the mass flowmeter converter according to the present invention. In the figure, 1 is a drive circuit, 2 is a drive coil, 3, 4 is a detection coil, and 5 is a phase detection. Circuit, 6 is a full-wave rectifier circuit, 7 is a frequency meter, 8 is C
A PU (Central Processing Unit) 9 is a reciprocal operation unit for frequency (hereinafter, referred to as a reciprocal operation unit).
【００２６】図２において、ドライブ回路１，駆動コイ
ル２，検出コイル３,４，位相検出回路５は、図３の場
合と同様の作用をするので、説明を省く。周波数計７
は、フローチューブの固有振動数を計測する手段である
が、実際には、前記固有振動数と同じ周波数を出力する
検出コイル３からの検出信号の周波数を計測するもの
で、検出コイル３の検出信号を整形し、得られた半周
期、又は１周期に対応した矩形波の零クロス時間をＣＰ
Ｕ８のクロック数として検知して呼び戻し、固有振動数
ｆを求めて逆数演算部９によりIn FIG. 2, the drive circuit 1, the drive coil 2, the detection coils 3, 4 and the phase detection circuit 5 operate in the same way as in FIG. Frequency meter 7
Is a means for measuring the natural frequency of the flow tube, but actually measures the frequency of the detection signal from the detection coil 3 that outputs the same frequency as the natural frequency. The signal is shaped, and the obtained zero-cross time of the rectangular wave corresponding to the half cycle or one cycle is defined as CP
It is detected as the clock number of U8 and called back, the natural frequency f is obtained, and the reciprocal operation unit 9
【００２７】[0027]
【数３】 (Equation 3)
【００２８】を求め、ＣＰＵ８に例えば簡略するために
ｎ＝１として記憶する。これが（２）に示すドリフト量
Ｚfとなる。Is stored in the CPU 8 as n = 1 for simplicity, for example. This is the drift amount Z f shown in (2).
【００２９】したがって、補正後の時間差Ｔｘは、 Ｔｘ＝Ｔａ−Ｚf …（３） （但し、Ｔａ：位相検出データ）（検出時間差） 更に、零点調整時のオフセットデータ値をＴoffとする
と、（３）式に加え、更にＴoffを補正することが精度
向上に寄与するので、ＣＰＵ８にＴoffを記憶しておく
ことにより、 Ｔｘ＝Ｔａ−Ｔoff−Ｚf …（４） とすることができる。Therefore, the corrected time difference Tx is: Tx = Ta−Z f (3) (where, Ta: phase detection data) (detection time difference) Further, if the offset data value at the time of zero point adjustment is T off , In addition to the equation (3), further correction of T off contributes to the improvement of accuracy. Therefore, by storing T off in the CPU 8, the following equation is obtained: Tx = Ta−T off −Z f (4) Can be.
【００３０】また、（２）式は、一般式で表現すると、Expression (2) can be expressed by a general expression as follows:
【００３１】[0031]
【数４】 (Equation 4)
【００３２】（但し、Ｚａ，Ｚｂ，ＺｃはＺfの係数）
とあらわすこともでき、（５）式に従って、ドリフト量
Ｚfを補正することもできる。もちろん、（５）式は別
の表現される逆数算式であってもよい。このような考え
方により（４）式に従ってドリフト量が補正された時間
差Ｔｘに基づいて、ドリフト影響のない正確な質量流量
を求めることができる。[0032] (however, the coefficient of Za, Zb, Zc is Z f)
Can also be expressed as, (5) in accordance with equation can be corrected for drift amount Z f. Of course, equation (5) may be another expressed reciprocal equation. Based on such a concept, an accurate mass flow rate without drift influence can be obtained based on the time difference Tx in which the drift amount is corrected according to the equation (4).
【００３３】[0033]
【発明の効果】以上の説明から明らかなように、本発明
によれば、以下の効果がある。請求項１に対応する効
果：フローチューブを固有振動数で駆動する方式のコリ
オリ流量計においては、流量範囲により定められたフロ
ーチューブの寸法，諸元や被測流体の密度により固有振
動数が変化し、固有振動、すなわち駆動周波数に応じた
時間差信号のドリフト量が生じ、誤差となるが、ドリフ
ト量は駆動周波数の逆数の関数であることが知られたの
で、駆動周波数を検知することにより、ドリフト量の補
正が可能となり、正確な質量流量を求めることができ
る。As is apparent from the above description, the present invention has the following effects. According to the Coriolis flowmeter of the type in which the flow tube is driven at the natural frequency, the natural frequency changes according to the dimensions of the flow tube determined by the flow rate range, the specifications, and the density of the fluid to be measured. Then, a natural vibration, that is, a drift amount of the time difference signal according to the driving frequency occurs, which results in an error, but since the drift amount is known to be a function of the reciprocal of the driving frequency, by detecting the driving frequency, The drift amount can be corrected, and an accurate mass flow rate can be obtained.
【図１】 固有振動数と時間差△Ｔのドリフト量との関
係を説明するための実験結果を示した図である。FIG. 1 is a diagram showing an experimental result for explaining a relationship between a natural frequency and a drift amount of a time difference ΔT.
【図２】 本発明による質量流量変換器の回路ブロック
を説明するための図である。FIG. 2 is a diagram for explaining a circuit block of the mass flow converter according to the present invention.
【図３】 従来の質量流量計変換器の構成を説明するた
めのブロック図である。FIG. 3 is a block diagram for explaining a configuration of a conventional mass flow meter converter.
【図４】 コリオリ質量流量計の時間差測定の一例を説
明するための図である。FIG. 4 is a diagram for explaining an example of time difference measurement of a Coriolis mass flow meter.
【図５】 従来のコリオリ流量計の零点オフセットを説
明するための図である。FIG. 5 is a diagram for explaining a zero point offset of a conventional Coriolis flowmeter.
１…ドライブ回路、２…駆動コイル、３,４…検出コイ
ル、５…位相検出回路、６…全波整流回路、７…周波数
計、８…ＣＰＵ（中央演算処理装置）、９…周波数の逆
数演算部。DESCRIPTION OF SYMBOLS 1 ... Drive circuit, 2 ... Drive coil, 3,4 ... Detection coil, 5 ... Phase detection circuit, 6 ... Full-wave rectification circuit, 7 ... Frequency meter, 8 ... CPU (Central processing unit), 9 ... Reciprocal of frequency Arithmetic unit.
Claims (1)
なくとも２点で支持し、該支持点まわりに一定振幅の固
有振動数で駆動したとき、該フローチューブに作用する
コリオリの力を位相差として検出し、位相差に比例した
時間差を計測して質量流量を求めるコリオリ流量計にお
いて、前記時間差を求める時間差計測手段と、前記固有
振動数を検出する周波数計測手段と、前記周波数計測手
段により検出された固有振動数の逆数を演算する逆数演
算手段とからなり、前記時間差計測手段により求められ
た時間差と前記逆数演算手段により演算された固有振動
数の逆数との差により零点ドリフト量を補正することを
特徴とする質量流量計変換器。1. A flow tube through which a fluid to be measured flows is supported at at least two points, and when driven at a natural frequency of a constant amplitude around the support point, a Coriolis force acting on the flow tube is detected as a phase difference. and, in the Coriolis flowmeter to determine the mass flow rate by measuring the time difference proportional to the phase difference, and time difference measuring means for determining the time difference, and frequency measuring means for detecting the natural frequency, the frequency measurement hand
Reciprocal calculating means for calculating the reciprocal of the natural frequency detected by the step, which is obtained by the time difference measuring means.
Time difference and natural vibration calculated by the reciprocal calculating means
A mass flowmeter converter for correcting a zero-point drift amount by a difference from a reciprocal of the number .
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10890195A JP2965242B2 (en) | 1995-05-02 | 1995-05-02 | Mass flow meter converter |
| US08/455,420 US5602346A (en) | 1994-06-06 | 1995-05-31 | Mass flowmeter converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10890195A JP2965242B2 (en) | 1995-05-02 | 1995-05-02 | Mass flow meter converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08304139A JPH08304139A (en) | 1996-11-22 |
| JP2965242B2 true JP2965242B2 (en) | 1999-10-18 |
Family
ID=14496507
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10890195A Expired - Fee Related JP2965242B2 (en) | 1994-06-06 | 1995-05-02 | Mass flow meter converter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2965242B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| MXPA06002093A (en) * | 2003-08-29 | 2006-05-25 | Micro Motion Inc | A method and apparatus for correcting output information of flow measurement apparatus. |
| JP2011043515A (en) * | 2010-10-25 | 2011-03-03 | Micro Motion Inc | Method and device for correcting output information from flow rate measuring device |
-
1995
- 1995-05-02 JP JP10890195A patent/JP2965242B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08304139A (en) | 1996-11-22 |
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