JP4561071B2 - Flow measuring device - Google Patents

Flow measuring device Download PDF

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JP4561071B2
JP4561071B2 JP2003335255A JP2003335255A JP4561071B2 JP 4561071 B2 JP4561071 B2 JP 4561071B2 JP 2003335255 A JP2003335255 A JP 2003335255A JP 2003335255 A JP2003335255 A JP 2003335255A JP 4561071 B2 JP4561071 B2 JP 4561071B2
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flow
flow path
transducer
flow rate
transducers
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JP2004045425A (en
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行夫 長岡
茂 岩永
紀夫 新村
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Panasonic Corp
Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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Description

本発明は、超音波を利用してガスなどの流量を計測する流量計測装置に関するものである。   The present invention relates to a flow rate measuring device that measures a flow rate of gas or the like using ultrasonic waves.

従来のこの種の流量計測装置は、例えば特許文献１に記載のものが知られており、図７に示すように、流路１を形成する流路部材２に超音波を送受信する矩形形状の第１送受波器３と第２送受波器４が配置されている。第１送受波器３から送信された超音波は図８に示すような矩形断面流路５を図７に示すように横断するように伝搬して第２送受波器４に到達する。逆に第２送受波器４から送信された場合には前述と同様に第１送受波器３に到達する。それぞれの超音波の伝搬時間は流路１内に流れがあると変化し、その伝搬時間は計測回路６によって測定され流量演算手段７で流量値に変換される。   A conventional flow measuring device of this type is known, for example, as described in Patent Document 1, and, as shown in FIG. 7, a rectangular shape that transmits and receives ultrasonic waves to and from a flow channel member 2 that forms the flow channel 1. A first transducer 3 and a second transducer 4 are arranged. The ultrasonic wave transmitted from the first transducer 3 propagates so as to cross the rectangular cross-section flow path 5 as shown in FIG. 8 as shown in FIG. 7 and reaches the second transducer 4. On the contrary, when it is transmitted from the second transducer 4, it reaches the first transducer 3 as described above. The propagation time of each ultrasonic wave changes when there is a flow in the flow path 1, and the propagation time is measured by the measurement circuit 6 and converted into a flow value by the flow rate calculation means 7.

第１および第２送受波器３、４の送受信面が矩形の形状をしており、その一辺を矩形の流路の短辺とほぼ同一の長さにすれば、図９に示すように短辺の流路全体の超音波を受信するので、流速分布の影響を解消して、流量係数を安定させるものである。
特開平９−１８９５８９号公報 If the transmission / reception surfaces of the first and second transducers 3 and 4 have a rectangular shape and one side thereof is substantially the same length as the short side of the rectangular flow path, the short side as shown in FIG. Since the ultrasonic waves of the entire side channel are received, the influence of the flow velocity distribution is eliminated and the flow coefficient is stabilized.
JP-A-9-189589

しかしながら、流量範囲が大きくなると計測流路の断面積も大きくなり、流路全域で計測するためには第１、第２送受波器３、４の受信面も大きくすることが必要であり、その結果機種によっては大型の送受波器を製作しなければならず、価格が高くなるという欠点があった。   However, as the flow rate range increases, the cross-sectional area of the measurement channel also increases, and in order to perform measurement across the entire channel, it is necessary to increase the reception surfaces of the first and second transducers 3 and 4. As a result, depending on the model, a large transmitter / receiver had to be manufactured, and the price was high.

本発明は上記課題を解決するもので、広範囲の流量を高精度で計測することを目的としている。   The present invention solves the above-described problems, and aims to measure a wide range of flow rates with high accuracy.

本発明は上記課題を解決するために、矩形の断面を有する流路と、前記流路の上流側と下流側に設けられ、前記流路を横断して音波を送信または受信する送受波器とを具備し、前記送受波器は、流路を流れる流体の平均流速域を検出できるように位置設定し、前記送受波器間の音波伝搬時間差で流体の流量を計測するものである。   In order to solve the above problems, the present invention provides a flow path having a rectangular cross section, and a transducer that is provided on the upstream side and the downstream side of the flow path and transmits or receives sound waves across the flow path. The transmitter / receiver is positioned so that an average flow velocity region of the fluid flowing through the flow path can be detected, and the flow rate of the fluid is measured by a difference in sound wave propagation time between the transmitter / receiver.

本発明によれば、流量の変化や温度変化あるいはガス種の変化に対して高精度の流量計測を行うことができるものである。   According to the present invention, a highly accurate flow rate measurement can be performed with respect to a flow rate change, a temperature change, or a gas type change.

本発明の実施の形態は、矩形の断面を有する流路と、前記流路の上流側と下流側に設けられ、前記流路を横断して音波を送信または受信する送受波器とを具備し、前記送受波器は、流路を流れる流体の平均流速域を検出できるように位置設定し、前記送受波器間の音波伝搬時間差で流体の流量を計測するもので、流れの量や温度に関わらず流量係数がほぼ一定で流量精度が高い。   An embodiment of the present invention includes a flow path having a rectangular cross section, and a transducer that is provided on the upstream side and the downstream side of the flow path and transmits or receives sound waves across the flow path. The transmitter / receiver is positioned so as to detect the average flow velocity range of the fluid flowing through the flow path, and measures the flow rate of the fluid by the sound wave propagation time difference between the transmitter / receiver. Regardless, the flow coefficient is almost constant and the flow accuracy is high.

また、流路の中心より所定長さ偏心させて前記送受波器を配置し、流れの量や温度に関わらず流量係数がほぼ一定で流量精度が高い。   In addition, the transducer is arranged with a predetermined length from the center of the flow path, and the flow coefficient is almost constant regardless of the flow amount and temperature, and the flow accuracy is high.

また、流路の長辺と短辺の比率は、１．１〜５の範囲内で決定するのが望ましい。   The ratio of the long side to the short side of the channel is preferably determined within a range of 1.1 to 5.

本発明の実施の形態では上記構成によって、流速分布に影響されない受信信号により流速を求めて流量を計測するものである。   In the embodiment of the present invention, with the above configuration, the flow rate is measured by obtaining the flow velocity from the received signal that is not affected by the flow velocity distribution.

以下、本発明の実施の形態について、図面を参照しながら説明する。なお、この実施の形態によって本発明が限定されるものではない。   Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

（実施の形態１）
図１は本発明の実施の形態１における流量計測装置の構成図で、図２は図１の側面図、図３は図１のＡ矢視図で、従来例と同一の構成部品には同一の番号を付している。流路１を形成する流路部材２に超音波を送受信する矩形形状の第１送受波器３と第２送受波器４が流れの上流と下流に配置されている。第１送受波器３と第２送受波器４とは流路に対して斜めに配置されているので、第１送受波器３から送信された超音波は図２に示すような矩形断面流路５を図１に示すように斜めに横断して伝搬し、第２送受波器４に到達する。 (Embodiment 1)
1 is a configuration diagram of a flow rate measuring apparatus according to Embodiment 1 of the present invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a view taken along arrow A in FIG. The number is attached. A rectangular first transducer 3 and second transducer 4 that transmit and receive ultrasonic waves to a channel member 2 that forms the channel 1 are arranged upstream and downstream of the flow. Since the first transducer 3 and the second transducer 4 are arranged obliquely with respect to the flow path, the ultrasonic wave transmitted from the first transducer 3 is a rectangular cross-section flow as shown in FIG. As shown in FIG. 1, it propagates obliquely across the path 5 and reaches the second transducer 4.

逆に第２送受波器４から送信された超音波は前述と同様に第１送受波器３に到達する。それぞれの超音波の伝搬時間は流路１内の流れの大きさによって変化する。この伝搬時間は計測回路６によって測定され流量演算手段７で流量値に変換される。   Conversely, the ultrasonic wave transmitted from the second transducer 4 reaches the first transducer 3 in the same manner as described above. The propagation time of each ultrasonic wave changes with the magnitude | size of the flow in the flow path 1. This propagation time is measured by the measuring circuit 6 and converted into a flow rate value by the flow rate calculation means 7.

次にその動作について述べる。伝搬時間は、静止流体中の音をｃ、流体の流れの速さをｖとすると、流れの順方向の超音波の伝搬速度は（ｃ＋ｖ）となる。送受波器３と４の間の距離をＬ、超音波伝搬軸と管路の中心軸とがなす角度をφとすると、上流から下流に超音波が伝搬する時間ｔ１は、
ｔ１＝Ｌ／（ｃ＋ｖＣＯＳφ） （１）
となり、下流から上流に伝搬する時間は、
ｔ２＝Ｌ／（ｃ−ｖＣＯＳφ） （２）
となり、Ｌとφが既知ならｔ１とｔ２を計測回路６で測定すれば流速ｖが求められる。 Next, the operation will be described. Propagation time is (c + v), where c is the sound in the static fluid and v is the velocity of the fluid flow. When the distance between the transducers 3 and 4 is L, and the angle between the ultrasonic propagation axis and the central axis of the pipe is φ, the time t1 during which the ultrasonic wave propagates from upstream to downstream is
t1 = L / (c + vCOSφ) (1)
The time to propagate from downstream to upstream is
t2 = L / (c−vCOSφ) (2)
If L and φ are known, the flow velocity v can be obtained by measuring t1 and t2 with the measuring circuit 6.

この流速より流量Ｑは、流路の通過面積をＳ、補正係数をＫとすれば、流量演算回路７で、
Ｑ＝ＫＳｖ （３）
を演算し流量を求める。 From this flow rate, the flow rate Q is determined by the flow rate calculation circuit 7 if the passage area of the flow path is S and the correction coefficient is K.
Q = KSv (3)
To calculate the flow rate.

流路１内の流速は一般に図１に示すように流速分布があり、その分布はレイノルズ数や上流の流れの乱れによって変化する。この流速分布は２次元的に発生し、図１に示すように矩形断面の長い方の一辺（長辺）と図３に示すように矩形断面の短い方の一辺（短辺）にも発生する。このように流速分布が存在する場合には、その伝搬時間はそれぞれの微小部分で受けた速度の変化を積分したものになる。   The flow velocity in the flow path 1 generally has a flow velocity distribution as shown in FIG. 1, and the distribution changes depending on the Reynolds number and upstream flow disturbance. This flow velocity distribution is generated two-dimensionally, and is also generated on one side (long side) of the longer rectangular section as shown in FIG. 1 and on the shorter side (short side) of the rectangular section as shown in FIG. . When the flow velocity distribution exists in this way, the propagation time is obtained by integrating the change in velocity received at each minute portion.

図３に示すように第１送受波器３と第２送受波器４はともに短辺Ｈよりも相当小さいから流路の一部分しか計測しない。第１、第２送受波器３、４を流路の中心に配置すれば流れの速い部分を多く計測するので、見かけの流量値は大きくなるので、流量係数Ｋを小さい値にして補正して流量を算出する。しかしながらこの流速分布は流量の大小によって変化するから補正係数をさらに環境条件によって補正しなければならない。   As shown in FIG. 3, since both the first transducer 3 and the second transducer 4 are considerably smaller than the short side H, only a part of the flow path is measured. If the first and second transducers 3 and 4 are arranged at the center of the flow path, many parts with a fast flow are measured, so the apparent flow rate value becomes large. Calculate the flow rate. However, since the flow velocity distribution changes depending on the flow rate, the correction coefficient must be further corrected according to environmental conditions.

本発明では第１、第２送受波器３、４の位置を中心より偏心量Ｌ１ほどずらしており、その結果第１、第２送受波器３、４は流路内５の平均流速の影響を受けた超音波を受信する。偏心量Ｌ１は流量の大小、流体の種類、流体の温度が変化しても平均流速を検出できるような位置を選定する。   In the present invention, the positions of the first and second transducers 3 and 4 are shifted from the center by an eccentric amount L1, and as a result, the first and second transducers 3 and 4 are affected by the average flow velocity in the flow path 5. Receive the received ultrasound. The eccentricity L1 is selected such that the average flow velocity can be detected even if the flow rate, fluid type, and fluid temperature change.

図４は流量が大きいときの流速分布であり、分布の差が小さくなっている。また第１、第２送受波器３、４の中央と端部とでは、送受信感度が異なるのが通常であるから、第１、第２送受波器３、４の中央部分の流れの影響を大きく受けることも考慮する必要がある。以上の要因を考慮すると偏心量Ｌ１は、短辺の長さＨと第１、第２送受波器３、４の短辺と相対する長さＷとの差の３０〜６０％好ましくは４０％程度が適切である。   FIG. 4 shows the flow velocity distribution when the flow rate is large, and the difference in distribution is small. Further, since the transmission and reception sensitivities are usually different between the center and the end of the first and second transducers 3 and 4, the influence of the flow at the center of the first and second transducers 3 and 4 is affected. It is necessary to consider receiving a large amount. Considering the above factors, the amount of eccentricity L1 is 30 to 60%, preferably 40% of the difference between the length H of the short side and the length W opposite to the short side of the first and second transducers 3 and 4. The degree is appropriate.

図５は偏心量Ｌ１を変化させたときの流量係数Ｋの値を示したものである。Ｌ１＝０．２Ｈの流量係数は流量値に関わらずほぼ一定であることがわかる。このように流量係数が一定であるということは、補正係数の設定がきわめて簡単にできマイコンの記憶容量の低減と、生産時の検定作業を容易にする。   FIG. 5 shows the value of the flow coefficient K when the eccentric amount L1 is changed. It can be seen that the flow coefficient of L1 = 0.2H is almost constant regardless of the flow value. The fact that the flow coefficient is constant in this way makes it very easy to set the correction coefficient, thereby reducing the memory capacity of the microcomputer and facilitating verification work during production.

また、流路内５の速度分布はレイノルズ数によって変化することが知られており、流量が変化しても流量係数が一定であるということは、レイノルズ数が変化しても流量係数が変化しないことを意味する。従って流体の温度変化や流体の種類が変更になっても、流量係数は変化しない。   Further, it is known that the velocity distribution in the flow path 5 changes depending on the Reynolds number, and that the flow coefficient is constant even if the flow rate changes, that is, the flow coefficient does not change even if the Reynolds number changes. Means that. Accordingly, the flow coefficient does not change even when the temperature of the fluid changes or the type of fluid changes.

第１、第２送受波器３、４の形状は矩形断面である方が平均流速を検出するのに好ましい。   The first and second transducers 3 and 4 are preferably rectangular in shape to detect the average flow velocity.

この場合第１、第２送受波器３、４の大きさは、小さすぎると平均流速をとらえにくく、大きいと大型になって価格が高くなるので、第１、第２送受波器３、４の一片は短辺Ｈの３０〜７０％の間が適している。第１、第２送受波器３、４が流路に対して小さすぎると、流れの変動に対して流量係数が安定でなくなる。また第１、第２送受波器３、４が短辺Ｈの長さに近づくと、広がった音波が流路の壁面に反射し直接波と干渉して受信感度に悪影響を及ぼす。   In this case, if the size of the first and second transducers 3 and 4 is too small, it is difficult to catch the average flow velocity, and if the size is large, the size becomes large and the price increases. Therefore, the first and second transducers 3 and 4 One piece is suitable between 30 and 70% of the short side H. If the first and second transducers 3 and 4 are too small relative to the flow path, the flow coefficient is not stable with respect to flow fluctuations. When the first and second transducers 3 and 4 approach the length of the short side H, the spread sound wave is reflected on the wall surface of the flow path and interferes with the direct wave to adversely affect the reception sensitivity.

第１、第２送受波器３、４は流路に機密性を有していなければならないので、矩形形状で機密性を保つことが困難であり、その場合には図６のように第１、第２送受波器３、４の外形９を円形にしてＯリングなどで機密性を容易に構成し、内部の超音波振動子８を矩形にすればよい。   Since the first and second transducers 3 and 4 must have confidentiality in the flow path, it is difficult to maintain confidentiality with a rectangular shape. The outer shape 9 of the second transducers 3 and 4 may be circular, and the confidentiality may be easily configured with an O-ring or the like, and the internal ultrasonic transducer 8 may be rectangular.

流路断面の形状は円形断面より矩形である方が平均流速を算出するのに適している。また矩形断面で短辺に対する長辺の比率を１．１〜５にすると流れが安定し、平均流速も安定して算出することができる。   The shape of the cross section of the flow path is more suitable for calculating the average flow velocity than the circular cross section. In addition, when the ratio of the long side to the short side is 1.1 to 5 in the rectangular cross section, the flow is stable and the average flow velocity can be calculated stably.

また、第１、第２送受波器３、４の上流に整流部材をもうけることにより、より一層の流量の高精度化が可能である。   Further, by providing a rectifying member upstream of the first and second transducers 3 and 4, it is possible to further increase the accuracy of the flow rate.

このように上記実施の形態によれば、次の効果が得られる。   Thus, according to the above embodiment, the following effects can be obtained.

（１）矩形の断面を有する流路と、前記流路の上流側と下流側に設けられ、前記流路を横断して音波を送信または受信する送受波器とを具備し、平均流速を検出できるように前記送受波器を、これら送受波器を配置した側の流路の中心より所定長さ偏心させて配置し、前記送受波器間の音波伝搬時間差で流体の流量を計測したので、流量の変化や温度変化あるいはガス種の変化に対して流量係数が変化せず、高精度の流量計測を行うことができる。   (1) A flow path having a rectangular cross section and a transducer that is provided upstream and downstream of the flow path and transmits or receives sound waves across the flow path, and detects an average flow velocity Since the transducer is arranged to be decentered by a predetermined length from the center of the flow path on the side where these transducers are arranged, and the flow rate of the fluid is measured by the difference in sound wave propagation time between the transducers, The flow coefficient does not change with respect to a change in flow rate, a change in temperature, or a change in gas type, and highly accurate flow rate measurement can be performed.

（２）流路の断面を長方形状とし、音波送受波器の偏心量が流路の短辺の長さと相対する送受波器の長さの差の３０〜６０％の範囲に設定したので、比較的簡単な構成で流量係数を一定にすることができ、流量精度が高い。   (2) Since the cross section of the flow path is rectangular, the eccentric amount of the sonic transducer is set in the range of 30 to 60% of the difference between the length of the transducer and the short side of the flow path, The flow coefficient can be made constant with a relatively simple configuration, and the flow accuracy is high.

（３）流路の長辺と短辺の比率が１．１〜５の範囲にしたので、流量係数の安定度がさらに高くなる。   (3) Since the ratio of the long side to the short side of the flow path is in the range of 1.1 to 5, the stability of the flow coefficient is further increased.

（４）音波送受波器の振動子が矩形で、その一辺は流路短辺の３０〜７０％にし、流量係数の安定化を維持しつつ、流路壁面からの反射を小さくし、送受信感度の低下を防止したので、流量精度が高い。   (4) The transducer of the acoustic wave transmitter / receiver is rectangular, and its one side is 30 to 70% of the short side of the flow path, and the reflection from the wall surface of the flow path is reduced while maintaining the stabilization of the flow coefficient, and the transmission / reception sensitivity. The flow rate accuracy is high.

以上のように、本発明に係る流量計測装置は、ガスなどの流体の流速、流量の計測に適用できる。   As described above, the flow rate measuring device according to the present invention can be applied to the measurement of the flow velocity and flow rate of a fluid such as gas.

本発明の第１の実施例の流量計測装置の構成図The block diagram of the flow volume measuring apparatus of 1st Example of this invention 同装置の流路構成の側面図Side view of the flow path configuration of the device 同装置の流路構成の断面図Sectional view of the flow path configuration of the device 同装置の流路構成の断面図Sectional view of the flow path configuration of the device 同装置の流量係数を示すグラフGraph showing the flow coefficient of the device 同装置の送受波器の実施例を示す構成図Configuration diagram showing an embodiment of the transducer of the same device 従来の流量計測装置の構成図Configuration diagram of a conventional flow measurement device 同装置の流路構成の側面図Side view of the flow path configuration of the device 同装置の流路構成の断面図Sectional view of the flow path configuration of the device

符号の説明Explanation of symbols

１ 矩形流路
３ 第１送受波器（音波送受波器）
４ 第２送受波器（音波送受波器） 1 rectangular flow path 3 first transducer (acoustic transducer)
4 Second transducer (Sound transducer)

Claims (3)

矩形の断面を有する流路と、前記流路の上流側と下流側に設けられ、前記流路を横断して音波を送信または受信する送受波器とを具備し、前記送受波器は、流路を流れる流体の平均流速域を検出できるように、前記流路の中心より所定長さ偏心させて前記送受波器を配置した流量計測装置。 A flow path having a rectangular cross section, and a transmitter / receiver that is provided on the upstream side and the downstream side of the flow path and transmits or receives a sound wave across the flow path. A flow rate measuring device in which the transducer is arranged eccentrically by a predetermined length from the center of the flow path so that an average flow velocity region of the fluid flowing through the path can be detected . 流路の断面は短辺と長辺を有する長方形状であって、対向する短辺側に送受波器を配置した請求項１記載の流量計測装置。 The channel cross-section is a rectangular shape having short sides and long sides, the flow rate measuring apparatus according to claim 1, wherein placing the transducer on the short side opposite. 流路の長辺と短辺の比率が１．１〜５の範囲である請求項２記載の流量計測装置。 The flow rate measuring device according to claim 2 , wherein the ratio of the long side to the short side of the flow channel is in a range of 1.1 to 5.
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WO1998048247A1 (en) * 1997-04-18 1998-10-29 Matsushita Electric Industrial Co., Ltd. Ultrasonic flowmeter
JP2002005705A (en) * 2000-06-19 2002-01-09 Matsushita Electric Ind Co Ltd Flow measuring device

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US4102186A (en) * 1976-07-23 1978-07-25 E. I. Du Pont De Nemours And Company Method and system for measuring flow rate
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WO1998048247A1 (en) * 1997-04-18 1998-10-29 Matsushita Electric Industrial Co., Ltd. Ultrasonic flowmeter
JP2002005705A (en) * 2000-06-19 2002-01-09 Matsushita Electric Ind Co Ltd Flow measuring device

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