JPH0771989A - Coriolis flowmeter - Google Patents
Coriolis flowmeterInfo
- Publication number
- JPH0771989A JPH0771989A JP21842693A JP21842693A JPH0771989A JP H0771989 A JPH0771989 A JP H0771989A JP 21842693 A JP21842693 A JP 21842693A JP 21842693 A JP21842693 A JP 21842693A JP H0771989 A JPH0771989 A JP H0771989A
- Authority
- JP
- Japan
- Prior art keywords
- tube
- counterbalance
- electromagnet
- pipe
- coriolis flowmeter
- 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
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- Measuring Volume Flow (AREA)
Abstract
Description
【０００１】[0001]
【技術分野】本発明は、コリオリ流量計に関し、より詳
細には、カウンタバランス方式のコリオリ流量計および
駆動手段に関する。TECHNICAL FIELD The present invention relates to a Coriolis flowmeter, and more particularly to a counterbalance type Coriolis flowmeter and driving means.
【０００２】[0002]
【従来技術】測定管を両端で支持し、支持された測定管
の中央部を軸線に垂直な方向に交番駆動している時、流
体が移動すると、測定管の中央部を中心として、測定管
の流入側と流出側に位相差が生ずる。この位相差は、コ
リオリの力に基づくもので、質量流量に比例した値であ
り、前記位相差を検知して質量流量を計測するコリオリ
流量計は周知である。2. Description of the Related Art When a fluid is moved while a measuring tube is supported at both ends and a central portion of the supported measuring tube is driven alternately in a direction perpendicular to an axis, the measuring tube is centered around the central portion of the measuring tube. There is a phase difference between the inflow side and the outflow side. This phase difference is based on the Coriolis force and is a value proportional to the mass flow rate, and Coriolis flow meters that detect the phase difference and measure the mass flow rate are well known.
【０００３】上述のごとく、コリオリ流量計は、両端支
持された測定管を駆動するための駆動手段を有し、通
常、駆動エネルギを最小とする測定管の固有振動数で駆
動される。このため、測定管と駆動手段と測定管の振幅
を検出するセンサ（コリオリ力の検出と共用される）
と、センサ信号を増幅し駆動手段を駆動する増幅回路と
で正帰還ループを形成して振幅一定となるように駆動さ
れる。As described above, the Coriolis flowmeter has driving means for driving the measuring tube supported at both ends, and is normally driven at the natural frequency of the measuring tube which minimizes the driving energy. Therefore, the measuring tube, the driving means, and the sensor for detecting the amplitude of the measuring tube (shared with the detection of the Coriolis force)
Then, a positive feedback loop is formed by the amplifier circuit that amplifies the sensor signal and drives the driving means, and the driving is performed so that the amplitude is constant.
【０００４】駆動手段は、例えば、電磁コイルとコアと
からなり、電磁コイルに交流電源を印加してコアを交番
吸引する電磁力を利用している。これらの駆動手段の電
磁コイルとコアとは各々、固定された基板と、該基板上
に両端支持された測定管とに装着される。しかし、測定
管をより効率よく駆動するために、上記基板の替りに、
測定管の固有振動数と等しい固有振動数を有する管体や
柱体又は板状体等の振動体（カウンタバランス）を用い
て、カウンタバランスを測定管と平行に支持体に支持
し、駆動手段をカウンタバランスと測定管との間に装着
して、カウンタバランスと測定管とを音叉（チューニン
グホーク）状に駆動する。このようなカウンタバランス
の構造は測定管の形状に応じて定められる。The driving means is composed of, for example, an electromagnetic coil and a core, and utilizes an electromagnetic force for alternately attracting the core by applying an AC power supply to the electromagnetic coil. The electromagnetic coil and core of these driving means are mounted on a fixed substrate and a measuring tube whose both ends are supported on the substrate. However, in order to drive the measuring tube more efficiently, instead of the above substrate,
Using a vibrating body (counter balance) having a natural frequency equal to the natural frequency of the measuring tube, such as a tube body, a columnar body, or a plate-like body, the counter balance is supported in parallel with the measuring tube by a support body, and driving means Is mounted between the counter balance and the measuring tube to drive the counter balance and the measuring tube in a tuning fork (tuning fork) shape. The structure of such a counter balance is determined according to the shape of the measuring tube.
【０００５】図４は、従来の直管形のカウンタバランス
管構造をもったコリオリ流量計の一例を示す図であり、
測定流体が流れる流管（図示せず）と接続される円筒状
の外筒２３を有し、外筒２３内には、外筒２３と同軸に
両端が接続された直管状の測定管２１と、該測定管２１
と同軸で大径のカウンタバランス管２２の両端とが固着
されており、測定管２１とカウンタバランス管２２との
中間部には鉄芯２４ａと電磁コイル２４ｂとからなる電
磁加振器２４が配設され、加振により測定管２１に生じ
たコリオリの力による位相変位を変位センサ２５，２６
で検出している。FIG. 4 is a diagram showing an example of a Coriolis flowmeter having a conventional straight tube type counterbalance tube structure,
It has a cylindrical outer cylinder 23 connected to a flow pipe (not shown) through which the measurement fluid flows, and inside the outer cylinder 23, a straight tubular measurement pipe 21 whose both ends are connected coaxially with the outer cylinder 23. , The measuring tube 21
Both ends of a counterbalance tube 22 having a large diameter and being coaxial with each other are fixed to each other, and an electromagnetic exciter 24 including an iron core 24a and an electromagnetic coil 24b is arranged at an intermediate portion between the measuring tube 21 and the counterbalance tube 22. The phase displacement caused by the Coriolis force generated in the measuring pipe 21 by the vibration sensor is provided to the displacement sensors 25, 26.
Is detected in.
【０００６】この構造では、測定管２１とカウンタバラ
ンス管２２との固有振動数が異なりチューニングホーク
状の駆動ができないので、例えば、カウンタバランス管
２２の中央に重錘２７を取り付けて両者の固有振動数を
等しくしている。In this structure, since the measuring tube 21 and the counterbalance tube 22 have different natural frequencies and cannot be driven in a tuning fork shape, for example, a weight 27 is attached to the center of the counterbalance tube 22 and the natural vibrations of the two are installed. The numbers are equal.
【０００７】図５は、従来の湾曲形のカウンタバランス
駆動構造をもったコリオリ流量計の一例を示す斜視図で
あり、支持板３３をＹ−Ｙ線上に貫通しＸ−Ｘ軸に軸対
称に両腕部を固着された測定管３１と、測定管３１と同
形で測定管３１と平行に支持部３３に固着されたカウン
タバランス管３２を有し、測定管３１とカウンタバラン
ス管３２とは所定条件でＹ−Ｙ軸方向に関し等しい固有
振動数をもっている。加振器３４は、Ｘ−Ｘ軸上の測定
管３１とカウンタバランス管３２との間に配設され、同
様に、センサ３５、３６はＸ−Ｘ軸と軸対称位置に配設
され、図４における前述と同様な動作がなされる。FIG. 5 is a perspective view showing an example of a Coriolis flowmeter having a conventional curved counterbalance drive structure. The support plate 33 is penetrated on the line Y--Y and is axially symmetrical about the line X--X. The measuring pipe 31 has both arms fixed thereto, and the counter balance pipe 32 has the same shape as the measuring pipe 31 and is fixed to the support portion 33 in parallel with the measuring pipe 31. The measuring pipe 31 and the counter balance pipe 32 have a predetermined shape. Under the condition, they have the same natural frequency in the Y-Y axis direction. The shaker 34 is arranged between the measuring pipe 31 and the counter balance pipe 32 on the X-X axis, and similarly, the sensors 35 and 36 are arranged at positions symmetrical with the X-X axis. The same operation as described above in 4 is performed.
【０００８】図６は従来の一般的な直管方式のカウンタ
バランス方式のコリオリ流量計の構造を示す図で、図に
おいて、測定管４０は、配管に対しフランジ４０ａ、４
０ｂで接続され、両端近傍に枠体４１が固着されてい
る。枠体４１内の測定管４０には、測定管４０を貫通固
着された支持板４２、４３が所定間隔を隔てて配設さ
れ、支持板４２、４３には流体が流れないカウンタバラ
ンス管４７が測定管４０と平行に固着されている。加振
器４４は測定管４０の中央にカウンタバランス管４７と
の間に固着されており、センサ４５、４６も同様に加振
器４４に関し対称位置に固着されている。しかし、コリ
オリ流量計は、目的に応じた種類の流体の流量を測定す
るものであるから、測定管には各種の測定流体が流れ
る。この結果、両端支持された測定管の固有振動数は、
測定流体の密度に応じて変化する。また、同一流体であ
っても、測定流体の温度に応じて密度が変化し固有振動
数が変化する。しかし、図４、図５、図６に示した測定
流体が流れないカウンタバランス管２２、３２、４７の
固有振動数は一定であり、測定管２１、３１、４０の固
有振動数との間に固有振動数の差が生じ、効率のよい駆
動することができず、しかも、コリオリの力による測定
管の変位量が変化し高精度な流量検出ができなくなると
いう問題があった。FIG. 6 is a view showing the structure of a conventional general straight tube type counterbalance type Coriolis flowmeter. In the figure, the measuring pipe 40 is provided with flanges 40a, 4a and 4b.
0b, and the frame 41 is fixed near both ends. Support plates 42 and 43, which are fixed through the measurement tube 40, are arranged at a predetermined interval in the measurement tube 40 in the frame 41, and a counter balance tube 47 in which a fluid does not flow to the support plates 42 and 43 is provided. It is fixed in parallel with the measuring tube 40. The vibrator 44 is fixed to the center of the measuring tube 40 between the counter balance tube 47 and the sensors 45 and 46 are also fixed to symmetrical positions with respect to the vibrator 44. However, since the Coriolis flowmeter measures the flow rate of a fluid of a type suitable for the purpose, various measurement fluids flow through the measuring pipe. As a result, the natural frequency of the measuring tube supported at both ends is
It changes depending on the density of the measurement fluid. Even with the same fluid, the density changes and the natural frequency changes depending on the temperature of the measurement fluid. However, the natural frequencies of the counter balance pipes 22, 32, 47 shown in FIGS. 4, 5, and 6 in which the measurement fluid does not flow are constant, and are between the natural frequencies of the measurement pipes 21, 31, 40. There is a problem that a difference in natural frequency occurs, efficient driving cannot be performed, and moreover, the amount of displacement of the measuring pipe due to Coriolis force changes and high-precision flow rate detection cannot be performed.
【０００９】[0009]
【目的】本発明は、上述の実情に鑑みてなされたもの
で、測定管内を流れる流体の密度が変化し、測定管の固
有振動数が変化しても、カウンタバランス管の固有振動
数が、測定管の固有振動数と等しくなるように制御して
高精度で安定した駆動ができるコリオリ流量計を提供す
ることを目的とする。[Object] The present invention has been made in view of the above circumstances, and even if the natural frequency of the measurement tube changes due to a change in the density of the fluid flowing in the measurement tube, the natural frequency of the counterbalance tube is An object of the present invention is to provide a Coriolis flowmeter that can be driven with high accuracy and stability by controlling the frequency to be equal to the natural frequency of the measuring tube.
【００１０】[0010]
【構成】本発明は、上記目的を達成するために、（１）
支持部材と、該支持部材に両端が支持され測定流体が流
れる測定管と、両端が前記支持部材に支持されるカウン
タバランス管と、該カウンタバランス管と測定管とに配
設され該測定管を長手方向に対して直角方向に駆動する
加振器と、前記測定管に作用するコリオリの力に応じ該
測定管と前記カウンタバランス管との所定２地点の間に
生ずる変位を検知する一対のセンサとを有し、該一対の
センサの位相差に比例した質量流量を出力するコリオリ
流量計において、前記加振器の加振エネルギを検知する
加振エネルギ検知手段と、前記測定管またはカウンタバ
ランスの中央部に重錘を懸架固着する重錘装着手段と、
該重錘装着手段を駆動し、前記加振エネルギ検知手段に
より検知された検知エネルギを最低とする重錘を前記測
定管又はカウンタバランスを固着するウエイト制御部と
からなること。更には、（２）前記（１）において、重
鐘装着手段を、カウンタバランス管の軸と直角で該カウ
ンタバランス管外壁に一端が固着された磁性材の磁石支
持柱と、該磁石支持柱を軸方向複数に区分した各々の断
面上該磁石支持柱を挾んだ対称位置に前記支持部材に固
着された複数の駆動磁石と、前記磁石支持柱と複数の各
々の駆動磁石との間に分割配設され、常時磁力により前
記前記磁石支持柱に吸引固着される重錘であり前記駆動
磁石の駆動により前記支持柱の固着を解き駆動磁石側に
磁気吸引される複数対の半環状磁性板とから構成したこ
と。更には、（３）前記（１）において、重錘装着手段
を、カウンタバランス管外壁面に固着された第１電磁石
と、該第１電磁石と所定間隔を隔て対向し支持部材に固
着された第２電磁石と、前記第１電磁石と第２電磁石と
の間に配設され重錘となる複数の磁性板とからなり、前
記第１電磁石と第２電磁石とに印加する電流差に基づい
て前記第１電磁石に磁気吸引される磁性板の数を可変と
する。更には、（４）前記（３）において、前記磁性板
を磁性粉としたことを特徴とする請求項３記載のコリオ
リ流量計を特徴とするものである。以下、本発明の実施
例に基づいて説明する。In order to achieve the above object, the present invention provides (1)
A support member, a measurement pipe whose both ends are supported by the support member and through which a measurement fluid flows, a counterbalance pipe whose both ends are supported by the support member, and the measurement pipe disposed on the counterbalance pipe and the measurement pipe. A vibrator that is driven in a direction perpendicular to the longitudinal direction, and a pair of sensors that detect a displacement that occurs between two predetermined points of the measurement tube and the counterbalance tube according to the Coriolis force acting on the measurement tube. In a Coriolis flowmeter that outputs a mass flow rate proportional to the phase difference between the pair of sensors, and a vibration energy detection means for detecting the vibration energy of the vibration exciter; Weight mounting means for suspending and fixing the weight in the central portion,
A weight control unit for driving the weight attachment means and fixing the weight that minimizes the detection energy detected by the vibration energy detection means to the measurement tube or the counter balance. Further, (2) in the above (1), the bell mounting means comprises a magnet supporting pillar made of a magnetic material, one end of which is fixed to an outer wall of the counterbalance tube at a right angle to an axis of the counterbalance tube, and the magnet supporting pillar. A plurality of drive magnets fixed to the support member at symmetrical positions sandwiching the magnet support column on each section divided into a plurality of axial directions, and divided between the magnet support column and each of the plurality of drive magnets. A plurality of pairs of semi-annular magnetic plates that are arranged and are always attracted and fixed to the magnet support column by magnetic force, and that are fixed to the drive magnet side by releasing the fixation of the support column by driving the drive magnet. It consisted of Further, (3) in the above (1), the weight attachment means is attached to a first electromagnet fixed to an outer wall surface of the counterbalance tube, and a first electromagnet opposed to the first electromagnet at a predetermined interval and fixed to a supporting member. The second electromagnet includes a plurality of magnetic plates that are disposed between the first electromagnet and the second electromagnet and serve as weights. Based on a current difference applied to the first electromagnet and the second electromagnet, The number of magnetic plates magnetically attracted to one electromagnet is variable. Further, (4) in (3) above, the magnetic plate is made of magnetic powder, and the Coriolis flowmeter according to claim 3 is characterized. Hereinafter, description will be given based on examples of the present invention.
【００１１】図１（ａ），（ｂ）は本発明によるコリオ
リ流量計の構造の一例を説明するための部分図である。
図１（ａ）はコリオリ流量計の要部断面図、図１（ｂ）
は，図１（ａ）の矢視Ｂ−Ｂ断面図で、図中、１は測定
管、２はカウンタバランス管、３は加振器、４は磁石支
持柱、、５ａ，５ｂは半環状磁性板、６ａ，６ｂは駆動
磁石、７ａ，７ｂは案内具、８はウエスト制御部、９は
加振電流検出器、１０は支持部材、１１は重錘装着手段
である。FIGS. 1A and 1B are partial views for explaining an example of the structure of the Coriolis flowmeter according to the present invention.
FIG. 1A is a cross-sectional view of the main part of the Coriolis flowmeter, and FIG. 1B.
Is a sectional view taken along the line BB of FIG. 1 (a), in which 1 is a measuring tube, 2 is a counterbalance tube, 3 is a vibrator, 4 is a magnet supporting column, and 5a and 5b are semi-annular. Magnetic plates, 6a and 6b are drive magnets, 7a and 7b are guides, 8 is a waist control unit, 9 is an exciting current detector, 10 is a support member, and 11 is a weight attachment means.
【００１２】測定管１とカウンタバランス管２とは同軸
で、支持部材９である支持筒（図示せず）内に両端部で
支持されている。測定管１とカウンタバランス管２との
中央部には、各々鉄芯３ａ、コイル３ｂとからなる加振
器３が取り付けられ、さらに、加振器３の両側対称位置
には変位のセンサ（図示せず）が取り付けられている。The measuring tube 1 and the counter balance tube 2 are coaxial with each other, and are supported at both ends in a supporting cylinder (not shown) which is a supporting member 9. A vibrator 3 including an iron core 3a and a coil 3b is attached to each of central portions of the measuring pipe 1 and the counterbalance pipe 2, and a displacement sensor (Fig. (Not shown) is attached.
【００１３】加振器３と反対側のカウンタバランス管２
の中央部壁面Ｐと支持部１０との間には重錘装着手段１
１が取り付けられれている。重錘装着手段１１は、磁石
支持柱４と、複数の対をなす半環状磁性板５ａ，５ｂ
と、複数の対をなす駆動磁石６ａ６ｂからなり、ウエイ
ト制御部８と加振電流検出器９とにより駆動される。磁
石支持柱４は、半環状磁性板５ａ，５ｂの厚さに対応し
た幅で、軸方向に区分された永久磁石、電磁石、あるい
は高透磁率のパーマロイ等の磁性材からなる柱状体で、
一端がカウンタバランス２の外周壁の中央部Ｐ位置に固
着され、他端は自由端となっている。半環状磁性板５
ａ，５ｂは、内周壁が磁石支持柱４の外周と等しい内径
を有する環状の強磁性板又は磁石板を直径方向に略２分
し、重錘となるもので、磁石支持柱４を軸方向に複数区
分した区分毎に一対となり、区分の数だけの対５ａ，５
ｂ；５ａ2，５ｂ2…（複雑となるため番号は付せず）を
もっている。Counterbalance tube 2 on the side opposite to the vibrator 3
Between the central wall surface P and the support portion 10 of the weight mounting means 1
1 is attached. The weight attachment means 11 includes a magnet support column 4 and a plurality of pairs of semi-annular magnetic plates 5a and 5b.
Is composed of a plurality of pairs of drive magnets 6a and 6b, and is driven by the weight controller 8 and the excitation current detector 9. The magnet support column 4 is a columnar body made of a magnetic material such as a permanent magnet, an electromagnet, or a high magnetic permeability permalloy having a width corresponding to the thickness of the semi-annular magnetic plates 5a and 5b,
One end is fixed to the central portion P position of the outer peripheral wall of the counter balance 2, and the other end is a free end. Semi-annular magnetic plate 5
Reference characters a and 5b are annular ferromagnetic plates or magnet plates whose inner peripheral wall has the same inner diameter as the outer circumference of the magnet support column 4 and bisects the magnet plate in the diametrical direction to form a weight. There is a pair for each of the multiple divisions, and there are as many pairs 5a, 5 as the number of divisions.
b; 5a 2 , 5b 2 ... (No number is attached because it is complicated).
【００１４】駆動磁石６ａ、６ｂは、例えば、電磁石か
らなり支持部９である支持筒内壁に固着され、半環状磁
性板５ａ，５ｂの対の数だけあるウエイト制御部８の指
令により、各々の半環状磁性板５ａ，５ｂに対応して磁
石支持柱４の軸方向に図中１、２、３、４、５で示すよ
うに配設され、該半環状磁性板５ａ，５ｂを吸着した
り、又は、反発磁極を形成して磁石支持柱４に磁気吸引
させる。このように、半環状磁性板５ａ，５ｂは、ウエ
イト制御部８の指令により駆動磁石５ａ，５ｂ側と磁石
支持柱４との間で吸着と離間を繰り返す。このときの半
環状磁性板５ａ，５ｂは、定められた直径方向の軌跡に
従って移動するが、必要に応じて案内具７ａ，７ｂを配
設して周方向の移動を防止できる。The drive magnets 6a and 6b are made of, for example, electromagnets and are fixed to the inner wall of the support cylinder which is the support portion 9. Each of the drive magnets 6a and 6b is commanded by the weight control portion 8 corresponding to the number of pairs of the semi-annular magnetic plates 5a and 5b. Corresponding to the semi-annular magnetic plates 5a and 5b, the semi-annular magnetic plates 5a and 5b are attracted by being arranged in the axial direction of the magnet support column 4 as indicated by 1, 2, 3, 4, and 5 in the figure. Alternatively, a repulsive magnetic pole is formed and magnetically attracted to the magnet supporting column 4. In this way, the semi-annular magnetic plates 5a and 5b repeat the attraction and separation between the drive magnets 5a and 5b side and the magnet support column 4 according to the command of the weight control unit 8. At this time, the semi-annular magnetic plates 5a and 5b move according to a predetermined diametrical trajectory, but guide members 7a and 7b can be provided as necessary to prevent circumferential movement.
【００１５】前述の如く、カウンタバランス方式の駆動
は測定管１の一方側の変位センサ（図示せず）の信号を
検出して、加振器３のコイル３ｂを測定管１の振幅が一
定となるように正帰還駆動する増幅回路に含まれる回路
部分をなすものであり、測定管１の固有振動数ｆMとカ
ウンタバランス管２の固有振動数ｆsとが等しいｆM=ｆs
のチューニングフォークの状態で駆動電流即ち駆動エネ
ルギーが最小になる。逆に、固有振動数が異なりｆM≠
ｆsの場合は駆動効率が悪くなり駆動電流が大きくな
る。加振電流検出器９は、この電流を検出する回路であ
る。一方、カウンタバランス管２および測定管１は、支
持部材に両端を固着されているので、各々の長さは等し
い。この状態でのカウンタバランス管２のばね定数をＫ
s'質量をＭs'とし、測定管１のばね定数をＫM'、質量を
ＭM'測定管５内に収容された測定流体の質量をＭLとす
ると、As described above, in the counter balance drive, the signal from the displacement sensor (not shown) on one side of the measuring tube 1 is detected, and the coil 3b of the vibrator 3 is set to have a constant amplitude. Therefore, the natural frequency f M of the measuring tube 1 and the natural frequency fs of the counter balance tube 2 are equal to each other. F M = fs
The drive current, that is, the drive energy is minimized in the tuning fork state. Conversely, the natural frequencies are different and f M ≠
In the case of fs, the driving efficiency becomes poor and the driving current becomes large. The excitation current detector 9 is a circuit that detects this current. On the other hand, since the counterbalance tube 2 and the measuring tube 1 are fixed at both ends to the supporting member, their lengths are equal. The spring constant of the counter balance tube 2 in this state is K
'Mass Ms' s and, the spring constant K M measuring tube 1 mass measurement fluid ', mass M M' is housed in the measuring pipe 5 When M L,
【００１６】[0016]
【数１】 [Equation 1]
【００１７】であらわされるが一般的には、（Ｋs/Ｍs)
＞（ＫM/ＭM+ＭL)であるから、 ｆs＞ｆM …(3) でカウンタバランス管２の固有振動数ｆsは測定管1の固
有振動数ｆMよりも大きい。従って、本発明では、駆動
電流が最小となるようにカウンタバランス管２に重錘を
付加し、カウンタバランス管２の固有振動数ｆsと測定
管１の固有振動数ｆMとを略等しくｆs≒ｆMとなるよう
にする。Generally, (Ks / Ms)
> (K M / M M + M L ), the natural frequency fs of the counterbalance tube 2 is larger than the natural frequency f M of the measuring tube 1 when fs> f M (3). Therefore, in the present invention, a weight is added to the counter balance tube 2 so that the drive current is minimized, and the natural frequency fs of the counter balance tube 2 and the natural frequency f M of the measuring tube 1 are substantially equal to fs≈. to be f M.
【００１８】ウエイト制御部８には駆動順序回路が組込
まれており加振電流検出器９の検出信号に基づいて駆動
磁石６ａ，６ｂを順次ＯＮ−ＯＦＦ駆動する。例えば、
ＯＦＦ時には半環状磁石５ａ，５ｂと駆動磁石６ａ，６
ｂとは反撥磁場を形成して半環状磁石５ａ，５ｂを磁石
支持柱４側に固着して質量Ｍsを増加させることにより
固定振動数ｆsを下げ、ＯＮ時には逆に駆動磁石６ａ，
６ｂ側に固着されることにより質量Ｍsを減少させｆsを
増加させる。A drive sequence circuit is incorporated in the weight controller 8 to sequentially drive the drive magnets 6a and 6b on and off based on a detection signal from the exciting current detector 9. For example,
When OFF, the semi-annular magnets 5a, 5b and the drive magnets 6a, 6
b, a repulsive magnetic field is formed to fix the semi-annular magnets 5a, 5b to the magnet support column 4 side to increase the mass Ms, thereby lowering the fixed frequency fs, and conversely when it is ON, the drive magnets 6a,
By being fixed to the 6b side, the mass Ms is decreased and fs is increased.
【００１９】図２は、本発明によるコリオリ流量計の、
他の実施例を説明するための部分図で、図中、１２、１
３は電磁石、１４は磁性板であり、図１と同じ作用をす
る部分には図１と同一の参照番号を付している。電磁石
１２は、カウンタバランス管２の中央外壁面に固着さ
れ、電磁石１３は電磁石１２と対向し支持部材９に固着
され、電磁石１２と１３とは反対向きの磁極となるよう
に各々電流ｉ1，ｉ2で駆動されている。更に、電磁石１
２と電磁石１３との間には複数の磁性板１４が配設され
電磁石１２と電磁石１３とに磁気吸引される。磁性板１
４は、電磁石１２に印加される電流ｉ1の大きさと、電
磁石１３に印加される電流ｉ2の大きさの磁場の強さに
従って吸着枚数が定められ、質量Ｍ1，Ｍ2が規定され
る。磁性板１４の吸着枚数が電磁石１２側が増加する方
向では質量Ｍ1が増加、固有振動数ｆsは低下し吸着枚数
が減少すると、質量Ｍ1が減少し、固有振動数ｆsは増大
する。このときの電磁石１２、１３の駆動電流ｉ1，ｉ2
の大きさは、加振電流検出器９の信号に従って定められ
ている。FIG. 2 shows a Coriolis flowmeter according to the present invention,
12 is a partial view for explaining another embodiment, in which 12, 1
Reference numeral 3 is an electromagnet, and 14 is a magnetic plate. The same reference numerals as in FIG. The electromagnet 12 is fixed to the central outer wall surface of the counterbalance tube 2, the electromagnet 13 is fixed to the support member 9 so as to face the electromagnet 12, and the electric currents i 1 and It is driven by i 2 . Furthermore, the electromagnet 1
A plurality of magnetic plates 14 are arranged between the electromagnets 2 and the electromagnets 13 and are magnetically attracted to the electromagnets 12 and 13. Magnetic plate 1
In No. 4, the number of adsorbed particles is determined according to the magnitude of the current i 1 applied to the electromagnet 12 and the strength of the magnetic field of the magnitude of the current i 2 applied to the electromagnet 13, and the masses M 1 and M 2 are defined. . In the direction in which the number of attracted magnetic plates 14 increases on the electromagnet 12 side, the mass M 1 increases, the natural frequency fs decreases, and when the number of attracted particles decreases, the mass M 1 decreases and the natural frequency fs increases. Driving currents i 1 and i 2 of the electromagnets 12 and 13 at this time
Is determined according to the signal from the exciting current detector 9.
【００２０】図３は、本発明によるコリオリ流量計の、
他の実施例を説明するための部分図であり、図中、１５
は磁性粉で、図１、２と同じ作用をする部分には、図
１、２と同一の参照番号を付している。図３の磁性粉１
５は、鉄、パーマロイ等の微粉体であり図２に示した磁
性板１４と同様の作用を有し、加振電流検出器９に基づ
いて、互いに反対磁極に励磁された電磁石１２、１３に
印加する電流ｉ1，ｉ2の大きさが定められる。この結
果、カウンタバランス管２側に付着する磁性粉１５の量
は電流ｉ1，ｉ2の大きさに従った質量Ｍ1となり、質量
Ｍ1に基づいて連続時にカウンタバランス管２の固有振
動数が定められる。以上の説明では図４に示した直管式
のカウンタバランス方式のコリオリ流量計について説明
したが、図５、６に示した湾曲管のカウンタバランス方
式のコリオリ流量にも適用できる。FIG. 3 shows a Coriolis flowmeter according to the present invention,
FIG. 15 is a partial view for explaining another embodiment, and in FIG.
Is a magnetic powder, and parts having the same functions as those in FIGS. 1 and 2 are denoted by the same reference numerals as those in FIGS. Magnetic powder 1 in Figure 3
Reference numeral 5 is a fine powder of iron, permalloy or the like, which has the same action as the magnetic plate 14 shown in FIG. 2, and the electromagnets 12 and 13 excited by the opposite magnetic poles based on the exciting current detector 9 The magnitudes of the applied currents i 1 and i 2 are determined. As a result, the amount of the magnetic powder 15 adhering to the counterbalance tube 2 side becomes a mass M 1 according to the magnitude of the currents i 1 and i 2 , and the natural frequency of the counterbalance tube 2 during continuous operation based on the mass M 1. Is determined. Although the straight pipe counterbalance Coriolis flowmeter shown in FIG. 4 has been described above, the present invention can also be applied to the curved counterbalance balance Coriolis flowmeter shown in FIGS.
【００２１】[0021]
【発明の効果】以上の説明から明らかなように、本発明
によると、カウンタバランス方式のコリオリ流量計にお
いて、測定流体の密度が変化して測定管の固有振動数が
変化した場合でも、所定の重錘を固着することにより、
カウンタバランス管の固有振動数を測定管の固有振動数
に略一致させることができる。この結果、コリオリの力
により変化する測定管の変化測定が常に一定条件で行わ
れるので測定精度が向上し、しかも効率のよい測定条件
が得られる。As is apparent from the above description, according to the present invention, in the counterbalance type Coriolis flowmeter, even when the density of the fluid to be measured changes and the natural frequency of the measuring tube changes, the predetermined frequency can be maintained. By fixing the weight,
The natural frequency of the counterbalance tube can be made to substantially match the natural frequency of the measuring tube. As a result, the measurement of the change in the measuring tube that changes due to the Coriolis force is always performed under constant conditions, so that the measurement accuracy is improved and more efficient measurement conditions are obtained.
【図１】本発明によるコリオリ流量計の構造を説明する
ための部分図である。FIG. 1 is a partial view for explaining the structure of a Coriolis flowmeter according to the present invention.
【図２】本発明によるオリオリ流量計の他の実施例を説
明するための部分図である。FIG. 2 is a partial view for explaining another embodiment of the orientation flow meter according to the present invention.
【図３】本発明によるコリオリ流量計の他の実施例を説
明するための部分図である。FIG. 3 is a partial view for explaining another embodiment of the Coriolis flowmeter according to the present invention.
【図４】従来の直管桂のカウンタバランス駆動構造をも
ったコリオリ流量計の一例を示す図である。FIG. 4 is a diagram showing an example of a Coriolis flowmeter having a conventional straight tube counterbalance drive structure.
【図５】従来の湾曲形のカウンタバランス駆動構造をも
ったコリオリ流量計の一例を示す斜視図である。FIG. 5 is a perspective view showing an example of a Coriolis flowmeter having a conventional curved counterbalance drive structure.
【図６】従来の直管方式のカウンタバランス方式のコリ
オリ流量計の構造を示す図である。FIG. 6 is a diagram showing a structure of a conventional straight tube type counterbalance type Coriolis flowmeter.
１…測定管、２…カウンタバランス管、３…加振器、４
…磁石支持柱、５ａ，５ｂ…半環状磁性板、６ａ，６ｂ
…駆動磁石、７ａ，７ｂ…案内具、８…ウエイト制御
部、９…加振電流検知部、１０…支持部材、１１…重錘
装着手段、１２、１３…電磁石、１４…磁性板、１５…
磁性粉。1 ... Measuring tube, 2 ... Counterbalance tube, 3 ... Shaker, 4
... Magnet support columns, 5a, 5b ... Semi-annular magnetic plates, 6a, 6b
... drive magnet, 7a, 7b ... guide tool, 8 ... weight control section, 9 ... excitation current detection section, 10 ... support member, 11 ... weight attachment means, 12, 13 ... electromagnet, 14 ... magnetic plate, 15 ...
Magnetic powder.
Claims (4)
れ測定流体が流れる測定管と、両端が前記支持部材に支
持されるカウンタバランス管と、該カウンタバランス管
と測定管とに配設され該測定管を長手方向に対して直角
方向に駆動する加振器と、前記測定管に作用するコリオ
リの力に応じ該測定管と前記カウンタバランス管との所
定の２地点の間に生ずる変位を検知する一対のセンサと
を有し、該一対のセンサの出力差に比例した質量流量を
出力するコリオリ流量計において、前記加振器の加振エ
ネルギを検知する加振エネルギ検知手段と、前記測定管
またはカウンタバランスの中央部に重錘を懸架固着する
重錘装着手段と、該重錘装着手段を駆動し、前記加振エ
ネルギ検知手段により検知された検知エネルギを最小と
するように重錘を前記測定管又はカウンタバランスに固
着するウエイト制御部とからなることを特徴とするコリ
オリ流量計。1. A support member, a measurement pipe having both ends supported by the support member and through which a measurement fluid flows, a counterbalance pipe having both ends supported by the support member, and the counterbalance pipe and the measurement pipe. A vibrating device for driving the measuring pipe in a direction perpendicular to the longitudinal direction, and a displacement generated between two predetermined points of the measuring pipe and the counterbalance pipe in accordance with the Coriolis force acting on the measuring pipe. In a Coriolis flowmeter that outputs a mass flow rate proportional to the output difference of the pair of sensors, and a vibration energy detection unit that detects the vibration energy of the vibrator. A weight attachment means for suspending and attaching a weight to the center portion of the measuring tube or the counter balance, and a weight attachment for driving the weight attachment means to minimize the detected energy detected by the vibration energy detection means. In front A Coriolis flowmeter characterized by comprising a weight control unit fixed to a measuring tube or a counter balance.
軸と直角で該カウンタバランス管外壁に一端が固着され
た磁性材の磁石支持柱と、該磁石支持柱を軸方向複数に
区分した各々の断面上該磁石支持柱を挾んだ対称位置に
前記支持部材に固着された複数の駆動磁石と、前記磁石
支持柱と複数の各々の駆動磁石との間に分割配設され、
常時磁力により前記前記磁石支持柱に吸引固着される重
錘であり前記駆動磁石の駆動により前記支持柱の固着を
解き駆動磁石側に磁気吸引される複数対の半環状磁性板
とから構成したことを特徴とする請求項１記載のコリオ
リ流量計。2. The bell mounting means comprises a magnet support pillar made of a magnetic material, one end of which is fixed to the outer wall of the counterbalance tube at a right angle to the axis of the counterbalance tube, and the magnet support pillar is divided into a plurality of pieces in the axial direction. A plurality of drive magnets fixed to the support member at symmetrical positions sandwiching the magnet support pillar on the cross section of the magnet support pillar, and the magnet support pillar and the plurality of drive magnets are separately arranged.
It is composed of a plurality of pairs of semi-annular magnetic plates, which are weights that are constantly attracted and fixed to the magnet support pillars by magnetic force, and that are fixedly attracted to the drive magnets by releasing the fixation of the support pillars by driving the drive magnets. The Coriolis flowmeter according to claim 1, wherein
壁面に固着された第１電磁石と、該第１電磁石と所定間
隔を隔て対向し支持部材に固着された第２電磁石と、前
記第１電磁石と第２電磁石との間に配設され重錘となる
複数の磁性板とからなり、前記第１電磁石と第２電磁石
とに印加する電流差に基づいて前記第１電磁石に磁気吸
引される磁性板の数を可変とする請求項１記載のコリオ
リ流量計。3. A weight mounting means, a first electromagnet fixed to an outer wall surface of a counterbalance tube, a second electromagnet opposed to the first electromagnet at a predetermined distance and fixed to a supporting member, and the first electromagnet. It is composed of a plurality of magnetic plates that are disposed between the electromagnet and the second electromagnet and serve as weights, and are magnetically attracted to the first electromagnet based on the current difference applied to the first electromagnet and the second electromagnet. The Coriolis flowmeter according to claim 1, wherein the number of magnetic plates is variable.
する請求項３記載のコリオリ流量計。4. The Coriolis flowmeter according to claim 3, wherein the magnetic plate is magnetic powder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21842693A JP2801849B2 (en) | 1993-09-02 | 1993-09-02 | Coriolis flow meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21842693A JP2801849B2 (en) | 1993-09-02 | 1993-09-02 | Coriolis flow meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0771989A true JPH0771989A (en) | 1995-03-17 |
| JP2801849B2 JP2801849B2 (en) | 1998-09-21 |
Family
ID=16719731
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21842693A Expired - Lifetime JP2801849B2 (en) | 1993-09-02 | 1993-09-02 | Coriolis flow meter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2801849B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19840782A1 (en) * | 1998-09-08 | 2000-03-30 | Krohne Messtechnik Kg | Mass flow meter |
-
1993
- 1993-09-02 JP JP21842693A patent/JP2801849B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19840782A1 (en) * | 1998-09-08 | 2000-03-30 | Krohne Messtechnik Kg | Mass flow meter |
| DE19840782C2 (en) * | 1998-09-08 | 2001-09-06 | Krohne Messtechnik Kg | Mass flow meter |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2801849B2 (en) | 1998-09-21 |
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