JP2013142539A - Mass flowmeter - Google Patents
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- JP2013142539A JP2013142539A JP2012001246A JP2012001246A JP2013142539A JP 2013142539 A JP2013142539 A JP 2013142539A JP 2012001246 A JP2012001246 A JP 2012001246A JP 2012001246 A JP2012001246 A JP 2012001246A JP 2013142539 A JP2013142539 A JP 2013142539A
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本発明は、質量流量計に関し、特に、小型・軽量な流量計での流量計測が必要な分野、例えば、人工心臓などの医療用流量計や、石油、石油化学、化学などのプラントの配管を流れる流体の流量計測や、ガス、ビンの洗浄水、ウェハや基板の洗浄液、薬剤などの流量計測に好適な質量流量計に関する。 The present invention relates to a mass flow meter, in particular, in a field where flow measurement is required with a small and lightweight flow meter, for example, a medical flow meter such as an artificial heart or a piping of a plant such as petroleum, petrochemical, chemical, etc. The present invention relates to a mass flowmeter suitable for measuring the flow rate of flowing fluid, and measuring the flow rate of gas, cleaning water for bottles, cleaning liquid for wafers and substrates, and chemicals.
病院外使用の体内埋め込み人工心臓では、病態管理のため流量表示が必要であるが、埋め込みできる小型の流量計が存在していない。産業用の流量計としては、渦流量計、抵抗流量計、フロート式流量計など様々な式はあるが、超軽量でシンプルな計測方式の流量計が求められている。
本発明者等は、先に、超軽量でシンプルな計測方式の質量流量計として、遠心力が発生する曲がり管を用い、曲がり部に遠心力検出用の歪ゲージと、直管部に静圧・温度補償用の歪ゲージを取り付け、その出力差から流量を計測する質量流量計を開発し、出願をしている(特許文献1、2参照)。
An implantable artificial heart used outside a hospital needs to display a flow rate for pathological management, but there is no small flow meter that can be implanted. There are various types of industrial flowmeters such as vortex flowmeters, resistance flowmeters, and float flowmeters, but ultra-lightweight and simple flowmeters are required.
The inventors previously used a bending tube that generates centrifugal force as an ultra-lightweight and simple measurement type mass flow meter, a strain gauge for detecting centrifugal force at the bending portion, and a static pressure at the straight tube portion.・ We have developed and filed a mass flow meter that attaches a strain gauge for temperature compensation and measures the flow rate from the output difference (see Patent Documents 1 and 2).
本発明者等が、先に提案してきた曲がり管を用いた質量流量計(特許文献1、2参照)では、計測方法はシンプルで小型化が可能だが、管路断面形状が円形の曲がり管を用いていたため、遠心力が発生する曲がり部では管路断面内で2次流れが生じ、しかも2次流れの影響により低流量と高流量で管路断面の流れのパターンが異なっているため、低流量と高流量で異なる校正式を事前に計測し、使用しなくては2次流れの影響を考慮した正確な流量計測結果を得ることができず、複雑な校正作業が必要となることがわかった。
図1は、本発明者等が先に出願した特許文献1、2の従来の曲がり管を用いた質量流量計であり、図示のごとく曲がり管は曲がり部とそれに連なる直管部とで構成され、曲がり管の管路断面の形状は曲がり部も直管部も円形である。図3は、図1で示した曲がり管の管路断面の形状が円形の質量流量計における、曲がり部における管路断面の2次流れを示した図であり、左側の図が低流量の場合の2次流れ、右側の図が高流量の場合の2次流れを示している。低流量では渦の中心が管路上面と下面に近い位置であるが、高流量では流れのパターンが変わり渦中心が管路中央に近い位置に移動している。正確な流量を得るためにはこの2次流れによる影響を事前に計測し校正式を求める必要があるが、図3に示すとおり高流量と低流量では2次流れのパターンが異なっており、複雑な校正式を求めなければならない。
また、曲がり管の歪ゲージ式センサ取付部の形状が半円の曲面となっているため、計測精度を向上させるための薄肉加工が困難であった。
本発明が解決しようとする課題は、2次流れによる流れのパターンの変化の小さい曲がり管を用いた質量流量計を提供するとともに、曲がり管の歪ゲージ式センサ取付部の薄肉加工の容易な質量流量計を提供することにある。
In the mass flowmeter using the bent pipe previously proposed by the present inventors (see Patent Documents 1 and 2), the measuring method is simple and can be reduced in size, but a bent pipe having a circular pipe cross-sectional shape is used. As a result, a secondary flow occurs in the cross section of the pipe at the bend where the centrifugal force is generated, and the flow pattern of the cross section of the pipe is different due to the influence of the secondary flow. If different calibration formulas are measured in advance for the flow rate and the high flow rate, it will not be possible to obtain accurate flow measurement results that take into account the effects of the secondary flow, and it will be necessary to perform complicated calibration work. It was.
FIG. 1 is a mass flow meter using the conventional bent pipes of Patent Documents 1 and 2 previously filed by the present inventors. As shown in the figure, the bent pipe is composed of a bent portion and a straight pipe portion connected to the bent portion. The shape of the pipe cross section of the bent pipe is circular in both the bent part and the straight pipe part. FIG. 3 is a diagram showing the secondary flow of the pipe cross section at the bent portion in the mass flowmeter having the circular pipe cross section of the bent pipe shown in FIG. Secondary flow, and the diagram on the right shows the secondary flow when the flow rate is high. At a low flow rate, the center of the vortex is close to the upper and lower surfaces of the pipe, but at a high flow rate, the flow pattern changes and the vortex center moves to a position near the center of the pipe. In order to obtain an accurate flow rate, it is necessary to measure the influence of the secondary flow in advance and obtain a calibration formula. However, as shown in Fig. 3, the secondary flow pattern is different between the high flow rate and the low flow rate. A correct calibration formula must be obtained.
In addition, since the shape of the strain gauge type sensor mounting portion of the bent pipe is a semicircular curved surface, it has been difficult to perform thin wall processing for improving measurement accuracy.
The problem to be solved by the present invention is to provide a mass flow meter using a bent pipe with a small change in flow pattern due to a secondary flow, and to easily mass-process the strain gauge sensor mounting portion of the bent pipe. To provide a flow meter.
上記課題を解決するために、本発明は、曲がり部とそれに連なる直管部とで構成された曲がり管を用い、曲がり部の外周の管壁に遠心力検出用の歪ゲージと、直管部の管壁に静圧・温度補償用の歪ゲージを取り付け、その出力差から流量を計測する質量流量計であって、曲がり部の管路断面の形状が、曲がり管の曲がり部の曲率半径方向に対して垂直方向が長い管路断面形状を用いる。
また、本流量計において、遠心力を計測する曲がり部のみ管路断面の曲率半径方向に対して垂直方向が長い管路断面を用いる。曲率半径方向に対して垂直方向が長い管路断面として、楕円、長方形、4隅にRを付けた長方形、短辺を半円に置き換えた長方形を用いる。
In order to solve the above-mentioned problems, the present invention uses a bent pipe composed of a bent portion and a straight pipe portion connected to the bent portion, a strain gauge for detecting centrifugal force on the outer peripheral wall of the bent portion, and a straight pipe portion. A mass flow meter with a strain gauge for static pressure / temperature compensation attached to the pipe wall and measuring the flow rate from the output difference, where the shape of the pipe section of the bent part is the radius direction of the bent part of the bent pipe The cross-sectional shape of the pipe having a long vertical direction is used.
Further, in the present flow meter, a pipe cross section having a long vertical direction with respect to a radius direction of curvature of the pipe cross section is used only at a bent portion where the centrifugal force is measured. As the pipe cross section having a long vertical direction with respect to the radius of curvature, an ellipse, a rectangle, a rectangle with four corners R, and a rectangle with a short side replaced with a semicircle are used.
本発明によれば、曲がり管を用いた質量流量計において、従来の円形の断面を持つ曲がり管に比べて、高流量時と低流量時の2次流れが管路両端のみに抑制され、管路断面に生じる渦の位置が変化しない。つまり、2次流れの影響による低流量と高流量で管路断面の流れのパターンに変化が少ないため、質量流量計の校正式を1つの式で簡易に表すことができるようになる。
さらに、歪ゲージ式センサを貼り付ける部分の管路断面が楕円形状や長方形形状とすることで、計測精度を向上させるための薄肉加工が容易となる。
According to the present invention, in a mass flow meter using a bent pipe, the secondary flow at a high flow rate and a low flow rate is suppressed only at both ends of the pipe as compared with a conventional bent pipe having a circular cross section. The position of the vortex generated in the road section does not change. That is, since there is little change in the flow pattern of the pipe cross section between the low flow rate and the high flow rate due to the influence of the secondary flow, the calibration formula of the mass flow meter can be easily expressed by one formula.
Furthermore, when the section of the pipe line where the strain gauge sensor is attached has an elliptical shape or a rectangular shape, thin processing for improving measurement accuracy is facilitated.
本発明は、曲がり部とそれに連なる直管部とで構成される曲がり管を用い、曲がり部に遠心力検出用の歪ゲージと、直管部に静圧・温度補償用の歪ゲージを取り付け、その出力差から流量を計測する質量流量計であって、少なくとも曲がり部の管路断面の形状が、曲がり管の曲がり部の曲率半径方向に対して垂直方向が長い管路断面を持つことを特徴とする質量流量計である。
前記のとおり、図1に示した従来の質量流量計では、管路断面の形状が円形状の曲がり部において、図3に示すような2次流れ(左:低流量、右:高流量)が発生し、低流量では渦の中心が管路上面(図での上面)と下面(図での下面)に近い位置であるが、高流量では流れのパターンが変わり渦中心が管路中央に近い位置に移動している。ここで、矢印の長さは最大流量で正規化した2次流れの大きさを表し、矢印の向きが2次流れの向きを表す。図3に示すように、低流量と高流量のいずれの場合も、歪みゲージ取り付け位置である曲がり部の外周において2次流れが発生しており、2次流れの影響が無視できない。そのため、正確な質量流量を得るためには事前に計測して校正式を求める必要があるが、低流量と高流量では2次流れのパターンが異なるので、2次流れの影響の校正が難しい。
これに対し、図2に示した本発明の質量流量計では、少なくとも曲がり部の管路断面の形状が、曲がり管の曲がり部の曲率半径方向に対して垂直方向が長い管路断面であるため、図4に示すような2次流れとなる。図3の従来の円形の断面を持つ曲がり管に比べて、図4の本発明では、曲がり部での高流量時と低流量時の2次流れが、曲がり部の曲率半径方向に対して垂直方向が長い管路断面の両端(図での上端及び下端)のみに抑制され、流れのパターンの変化が小さく、しかも歪ゲージ取り付け位置である曲がり部の外周での2次流れの影響はほとんどみられないため、質量流量計の校正式を1つの式で簡易に表すことができるようになる。
さらに、曲がり部の外周の歪ゲージ取り付け位置の形状が管路断面で直線又は直線に近く、従来の円管の半円の場合に比べて薄肉加工が容易な形状となる。
The present invention uses a bent pipe composed of a bent portion and a straight pipe portion connected to the bent portion, and attaches a strain gauge for centrifugal force detection to the bent portion and a strain gauge for static pressure and temperature compensation to the straight pipe portion, Mass flow meter that measures flow rate from the output difference, characterized in that at least the shape of the pipe cross section of the bent part has a long pipe cross section perpendicular to the radius of curvature of the bent part of the bent pipe This is a mass flow meter.
As described above, in the conventional mass flow meter shown in FIG. 1, the secondary flow (left: low flow rate, right: high flow rate) as shown in FIG. At low flow rate, the center of the vortex is close to the upper surface (upper surface in the figure) and lower surface (lower surface in the figure), but at high flow rate, the flow pattern changes and the vortex center is closer to the center of the pipe line Moved to position. Here, the length of the arrow represents the magnitude of the secondary flow normalized by the maximum flow rate, and the direction of the arrow represents the direction of the secondary flow. As shown in FIG. 3, in both cases of low flow rate and high flow rate, a secondary flow is generated on the outer periphery of the bent portion, which is the strain gauge mounting position, and the influence of the secondary flow cannot be ignored. Therefore, in order to obtain an accurate mass flow rate, it is necessary to measure in advance and obtain a calibration formula. However, since the secondary flow pattern is different between the low flow rate and the high flow rate, it is difficult to calibrate the influence of the secondary flow.
On the other hand, in the mass flowmeter of the present invention shown in FIG. 2, at least the shape of the pipe cross section of the bent portion is a pipe cross section that is long in the direction perpendicular to the radius of curvature of the bent portion of the bent pipe. The secondary flow is as shown in FIG. Compared with the conventional curved pipe having the circular cross section of FIG. 3, in the present invention of FIG. 4, the secondary flow at the high flow rate and the low flow rate at the bent portion is perpendicular to the curvature radius direction of the bent portion. The flow direction is restrained only at both ends (upper and lower ends in the figure) of the long section of the pipe, the change in the flow pattern is small, and the influence of the secondary flow at the outer periphery of the curved part where the strain gauge is attached is almost insignificant. Therefore, the calibration formula of the mass flow meter can be expressed simply by one formula.
In addition, the shape of the strain gauge mounting position on the outer periphery of the bent portion is a straight line or a straight line in the cross section of the pipe, and the shape of the thin wall processing is easier than in the case of a semicircle of a conventional circular pipe.
なお、図2及び図4では、曲がり部の管路断面の形状は、隅にRのついた長方形断面で、長方形の長辺が曲がり管の曲がり部の曲率半径方向に対して垂直なものを示したが、管路断面の形状は長方形断面に限定されることなく、楕円形状であっても良く、あるいは図5に示すような長方形の短辺を半円に置き換えたものであっても良い。
また、図2では直管部も曲がり部と同じ管路断面形状としたが、図5及び図6のように直管部の断面形状は円形断面とし、曲がり部のみの管路断面の形状が、曲がり管の曲がり部の曲率半径方向に対して垂直方向が長い管路断面としてもよい。
2 and 4, the pipe cross-sectional shape of the bent portion is a rectangular cross section with an R at the corner, and the long side of the rectangle is perpendicular to the radius of curvature of the bent portion of the bent pipe. Although shown, the shape of the pipe cross section is not limited to the rectangular cross section, and may be an elliptical shape, or may be one in which the short side of the rectangle as shown in FIG. 5 is replaced with a semicircle. .
In FIG. 2, the straight pipe portion has the same pipe cross-sectional shape as the bent portion, but the straight pipe portion has a circular cross section as shown in FIGS. The pipe cross section may be long in the direction perpendicular to the radius of curvature of the bent portion of the bent pipe.
図5及び図6に本発明の質量流量計の一実施例を示す。本実施例の曲がり管は、曲がり部とそれに連なる直管部とからなり、図示のごとく直管部の管路断面の形状は円形形状であり、曲がり部の管路断面の形状は、長方形の短辺を半円で置き換えた形状であって、長方形の長辺が曲がり管の曲がり部の曲率半径方向に対して垂直となっており、曲がり部と直管部との接続部分では断面形状をなめらかに変化させて断面形状の変化により流れが乱れないようにしてある。
図6は、歪ゲージセンサを管路外周から貼り付けるため、管路を薄肉加工したセンサ貼付け部の形状を説明した図であって、曲がり部の外周に遠心力計測用センサを取り付け、直管部に静圧補償用(温度補償用を兼ねる、以下「静圧・温度補償用」という)センサを取り付ける。曲がり管は流体圧によって大きな弾性変形を生じない程度の硬質の管を用い、曲がり部の外周において遠心力計測用センサを取り付ける部分は、適宜の研削等の薄肉加工を行って薄肉部とし、曲がり管内を流動する流体が、曲がり部で流動方向を変えるときの遠心力によって変形しやすくしておく。同様に、直管部において静圧・温度補償用センサを取り付ける部分も薄肉加工を行って薄肉部としておく。
曲がり部の外周に取り付けた遠心力計測用センサで遠心力と静圧の合計圧力を検出し、直管部に取り付けた静圧・温度補償用センサで静圧及び温度に関連した圧力を検出し、歪センサ計測で慣用されているブリッジ回路などを用いて両者の出力差から質量流量を求めることが出来る(特許文献1、2参照)。
5 and 6 show an embodiment of the mass flow meter of the present invention. The bent pipe of the present embodiment is composed of a bent portion and a straight pipe portion connected to the bent portion, and the shape of the pipe cross section of the straight pipe portion is circular as shown in the figure, and the shape of the pipe cross section of the bent portion is rectangular. The short side is replaced with a semicircle, and the long side of the rectangle is perpendicular to the radius of curvature of the bent part of the bent pipe, and the cross-sectional shape is the connection part between the bent part and the straight pipe part. The flow is smoothly changed so that the flow is not disturbed by the change in the cross-sectional shape.
FIG. 6 is a diagram illustrating the shape of a sensor pasting portion in which the pipe line is thinned so that the strain gauge sensor is pasted from the outer periphery of the pipe, and a centrifugal force measuring sensor is attached to the outer circumference of the bent part. A sensor for static pressure compensation (also used for temperature compensation, hereinafter referred to as “static pressure / temperature compensation”) is attached to the section. The bending pipe is a rigid pipe that does not cause large elastic deformation due to fluid pressure, and the part to which the centrifugal force measurement sensor is attached on the outer periphery of the bending part is thinned by appropriate thinning such as grinding. The fluid flowing in the tube is easily deformed by the centrifugal force when the flow direction is changed at the bent portion. Similarly, the portion to which the static pressure / temperature compensation sensor is attached in the straight pipe portion is also thinned to be a thin portion.
The centrifugal force measurement sensor attached to the outer periphery of the bending part detects the total pressure of centrifugal force and static pressure, and the static pressure and temperature compensation sensor attached to the straight pipe part detects static pressure and temperature related pressure. The mass flow rate can be obtained from the difference between the outputs using a bridge circuit or the like commonly used in strain sensor measurement (see Patent Documents 1 and 2).
本実施例では、曲がり部の管路断面の形状を、長方形の短辺を半円で置き換えた形状であって、長方形の長辺が曲がり管の曲がり部の曲率半径方向に対して垂直となるものを採用したので、図4で示した管路断面内の2次流れのパターンと同様に、2次流れは長方形の短辺を半円で置き換えた両端のみに抑制されるので、曲がり部外周の遠心力計測用センサの取り付け位置での2次流れの影響はほとんどない。
また、本実施例では、曲がり部外周のセンサ取り付け位置での薄肉加工が、この位置での管壁の形状が従来の円管のものより加工が容易であり、また、曲がり部を曲げ加工で加工したときの影響が、従来の円管の場合より少ないので、薄肉加工が容易である。
In this embodiment, the shape of the pipe cross section of the bent portion is a shape in which the short side of the rectangle is replaced with a semicircle, and the long side of the rectangle is perpendicular to the direction of the radius of curvature of the bent portion of the bent tube. Since the secondary flow is restrained only at both ends with the short side of the rectangle replaced by a semicircle, as with the secondary flow pattern in the pipe cross section shown in FIG. There is almost no influence of the secondary flow at the mounting position of the centrifugal force measuring sensor.
Further, in this embodiment, the thin wall processing at the sensor mounting position on the outer periphery of the bent portion is easier to process than the conventional circular tube shape of the tube wall at this position, and the bent portion can be bent. Since the influence of processing is less than in the case of a conventional circular tube, thin wall processing is easy.
本発明の質量流量計は体内埋め込み用の人工心臓の流量計として好適であるが、他の手術用血液ポンプなどの医療用機器の流量計として、あるいは工業用の流量計としても適用できる。 The mass flow meter of the present invention is suitable as a flow meter for an artificial heart for implantation in the body, but can also be applied as a flow meter for other medical devices such as a blood pump for surgery or an industrial flow meter.
Claims (3)
少なくとも曲がり部の管路断面の形状が、曲がり管の曲がり部の曲率半径方向に対して垂直方向が長い管路断面形状を持つことを特徴とする質量流量計。 Using a bent pipe composed of a bent part and a straight pipe part connected to it, a strain gauge for detecting centrifugal force is provided on the outer peripheral wall of the bent part, and a strain for static pressure / temperature compensation is provided on the pipe wall of the straight pipe part. A mass flow meter that attaches a gauge and measures the flow rate from its output difference,
A mass flow meter characterized in that at least a shape of a pipe cross section of a bent portion has a pipe cross sectional shape that is long in a direction perpendicular to a curvature radius direction of a bent portion of the bent pipe.
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Cited By (3)
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JP2016118505A (en) * | 2014-12-22 | 2016-06-30 | 国立研究開発法人産業技術総合研究所 | Flowmeter |
CN110299300A (en) * | 2019-07-11 | 2019-10-01 | 晶澳太阳能有限公司 | The scaling method of the mass flowmenter of board-like PECVD device |
DE102022126228A1 (en) | 2022-10-10 | 2024-04-11 | Diehl Metering Gmbh | Fluid meters, especially water meters |
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JP2007218775A (en) * | 2006-02-17 | 2007-08-30 | National Institute Of Advanced Industrial & Technology | Mass flowmeter |
Cited By (4)
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