JP4888464B2 - Flow measuring device - Google Patents

Flow measuring device Download PDF

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JP4888464B2
JP4888464B2 JP2008263818A JP2008263818A JP4888464B2 JP 4888464 B2 JP4888464 B2 JP 4888464B2 JP 2008263818 A JP2008263818 A JP 2008263818A JP 2008263818 A JP2008263818 A JP 2008263818A JP 4888464 B2 JP4888464 B2 JP 4888464B2
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fluid
flow rate
transmission
type
flow
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JP2009008692A (en
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行夫 長岡
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Panasonic Corp
Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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本発明は、ガスなどの流体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 the flow rate of a fluid such as a gas.

従来のこの種の流量計測装置は、図8に示すように、流速検出手段1で接続した受信手段2より流量計測時の伝搬時間差検出手段3によって信号伝搬時間を計測し、伝搬時間記憶手段4の記憶値と比較判定し、記憶値より受信手段での計測が長い場合には異媒体が混入したことを検知し警告表示をするものであった。
特開平10−318811号公報
As shown in FIG. 8, the conventional flow measuring device of this type measures the signal propagation time by the propagation time difference detecting means 3 at the time of measuring the flow rate from the receiving means 2 connected by the flow velocity detecting means 1, and the propagation time storage means 4 When the measurement by the receiving means is longer than the stored value, it is detected that a different medium is mixed and a warning is displayed.
Japanese Patent Laid-Open No. 10-318811

しかしながら、上記従来の流量計測装置では、異媒体が混入したことは検出できるものの混入した状態で正確に流量を計測することができず、ガスの成分が変化する状態で流量精度を保つことが課題となっていた。   However, in the above conventional flow rate measuring device, although it can be detected that a different medium is mixed, the flow rate cannot be accurately measured in the mixed state, and it is a problem to maintain the flow rate accuracy in a state where the gas component changes. It was.

本発明は上記課題を解決するために、流体中に超音波を送受信する送受信器と、流れの上流から下流への送信もしくは下流から上流への送信の伝搬時間を計測する計測回路と、超音波伝搬時間により流量を算出する流量演算手段と、前記送受信器から前記流路内の流体の種類を判定する流体判別手段と、計測回路の定数を流体判別手段の値によって変更する回路定数補正手段とを備えた流量計測装置において、超音波の受信後に遅延手段を介して再度送信する繰り返し手段と、この繰り返し送受信の積算時間から流量を算出する繰り返し流量演算手段とを備え、流体判別手段によって前記遅延手段の設定を変更するものである。   In order to solve the above problems, the present invention provides a transceiver for transmitting and receiving ultrasonic waves in a fluid, a measurement circuit for measuring a propagation time of transmission from upstream to downstream of a flow or transmission from downstream to upstream, and ultrasonic waves Flow rate calculating means for calculating a flow rate according to propagation time, fluid determining means for determining the type of fluid in the flow path from the transmitter / receiver, and circuit constant correcting means for changing the constant of the measurement circuit according to the value of the fluid determining means A repetitive unit that transmits the ultrasonic wave again after receiving the ultrasonic wave, and a repetitive flow rate calculating unit that calculates a flow rate from the accumulated time of the repetitive transmission / reception. The setting of the means is changed.

超音波の受信後に遅延手段を介して再度送信する繰り返し手段と、この繰り返し送受信の積算時間から流量を算出する繰り返し流量演算手段とを備え、流体判別手段によって遅延手段の設定を変更するので、ガス種によって異なる超音波の反射を防止して流量精度を高めることができる。   Since the repetition means for transmitting again through the delay means after reception of the ultrasonic wave and the repetition flow rate calculation means for calculating the flow rate from the accumulated time of this repeated transmission and reception, the setting of the delay means is changed by the fluid discrimination means. It is possible to improve the flow rate accuracy by preventing the reflection of ultrasonic waves that differ depending on the species.

本発明は流体中に超音波を送受信する送受信器と、流れの上流から下流への送信もしくは下流から上流への送信の伝搬時間を計測する計測回路と、超音波伝搬時間により流量を算出する流量演算手段と、前記送受信器の信号から前記流路内の流体の種類を判定する流体判別手段と、前記計測回路の定数を前記流体判別手段で判別した流体の種類に応じて変更する回路定数補正手段とを備えた流量計測装置において、超音波の受信後に遅延手段を介して再度送信する繰り返し手段と、この繰り返し送受信の積算時間から流量を算出する繰り返し流量演算手段とを備え、回路定数補正手段は、流体判別手段で判別した流体の種類に応じて前記遅延手段の設定を変更するものである。 The present invention relates to a transmitter / receiver for transmitting / receiving ultrasonic waves in a fluid, a measurement circuit for measuring a propagation time of transmission from upstream to downstream of a flow or transmission from downstream to upstream, and a flow rate for calculating a flow rate by the ultrasonic propagation time. Calculation means, fluid discrimination means for determining the type of fluid in the flow path from the signal of the transceiver, and circuit constant correction for changing the constant of the measurement circuit according to the type of fluid determined by the fluid discrimination means A flow rate measuring device comprising: a repeating unit that transmits again through a delay unit after receiving an ultrasonic wave; and a repetitive flow rate calculating unit that calculates a flow rate from an accumulated time of the repeated transmission and reception, and a circuit constant correcting unit. Is to change the setting of the delay means according to the type of fluid determined by the fluid determination means.

以下、本発明の実施の形態を図面にもとづいて説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(実施の形態1)
本発明の実施の形態1を説明する。図1において、流体中に超音波を送受信する送受信器5と6が流路7の上流と下流にそれぞれ設けられ、流れの上流から下流への送信もしくは下流から上流への送信の伝搬時間を計測する計測回路8があり、この計測回路8の結果
として超音波伝搬時間が得られ、流量演算手段9によって流量が算出される。また、送受信器5と6の信号の大きさや伝搬時間から流路内の流体の種類を判定する流体判別手段10があって、流体判別手段10の値によって計測回路8の定数を変更する回路定数補正手段11とを備えている。
(Embodiment 1)
Embodiment 1 of the present invention will be described. In FIG. 1, transmitters / receivers 5 and 6 for transmitting / receiving ultrasonic waves in a fluid are provided upstream and downstream of a flow path 7, respectively, and the propagation time of transmission from upstream to downstream or transmission from downstream to upstream is measured. The ultrasonic propagation time is obtained as a result of the measurement circuit 8, and the flow rate is calculated by the flow rate calculation means 9. Further, there is a fluid discriminating means 10 for judging the type of fluid in the flow path from the signal magnitudes and propagation times of the transceivers 5 and 6, and a circuit constant for changing the constant of the measuring circuit 8 according to the value of the fluid discriminating means 10. And correction means 11.

次に動作について述べる。スタート12の信号により計測回路8の送信手段13から超音波駆動信号が送出され切換手段14を介して超音波が送受信器5から6へすなわち流れに沿って送信され、流路7内を伝搬した超音波は流れの速度分だけ速くなって送受信器6に到達する。送受信器6での信号は増幅手段15で増幅され、さらに比較手段16へ送られ超音波の受信を検出する。送受信器5から6までの超音波の送信時間を計時手段17で計測され、順方向伝搬時間として保存される。次に切換手段14を切り換えて送受信器6から5へ流れに逆らって超音波が送信され、前述と同様に送受信器6から5までの送信時間を逆方向伝搬時間として保存され、この逆方向伝搬時間と順方向伝搬時間の時間差と、流路7の断面積と流れの状態によってあらかじめ算出されている流量係数から流量演算手段9で流量を算出する。実際の演算では音速の影響が理論的になくなるように伝搬時間の逆数差を基に流量を算出している。   Next, the operation will be described. An ultrasonic drive signal is transmitted from the transmission means 13 of the measurement circuit 8 by the signal of the start 12, and ultrasonic waves are transmitted from the transceivers 5 to 6 through the switching means 14, that is, along the flow, and propagate through the flow path 7. The ultrasonic wave reaches the transmitter / receiver 6 after being accelerated by the flow velocity. The signal in the transmitter / receiver 6 is amplified by the amplifying means 15 and further sent to the comparing means 16 to detect reception of ultrasonic waves. The ultrasonic transmission time from the transceivers 5 to 6 is measured by the time measuring means 17 and stored as the forward propagation time. Next, the switching means 14 is switched to transmit ultrasonic waves against the flow from the transceivers 6 to 5, and the transmission time from the transceivers 6 to 5 is stored as the backward propagation time in the same manner as described above. The flow rate calculation means 9 calculates the flow rate from the time difference between the time and the forward propagation time, and the flow rate coefficient calculated in advance according to the cross-sectional area of the flow path 7 and the flow state. In the actual calculation, the flow rate is calculated based on the reciprocal difference of the propagation time so that the influence of the sound speed is theoretically eliminated.

次に流路7を流れる流体の種類が変化した場合について述べる。家庭に供給されている燃料としての天然ガスやLPガスの成分は常に一定ではなく季節や供給場所によって相当変化している。流体の成分が変化すると、送受信器6の信号も変化する。例えばLPガスの主成分であるプロパンガスの中に水素ガスが混入されると超音波の受信電圧は小さくなり、伝搬時間も小さくなる。流体判別手段10では受信電圧や伝搬時間を検出してその値からガスの種類を判別し計測回路8の回路定数を回路定数補正手段11で例えば増幅度や送信電圧を補正して流量精度を維持するように作用する。   Next, the case where the type of fluid flowing through the flow path 7 is changed will be described. The components of natural gas and LP gas as fuel supplied to the home are not always constant, and vary considerably depending on the season and place of supply. When the fluid component changes, the signal of the transceiver 6 also changes. For example, when hydrogen gas is mixed in propane gas, which is the main component of LP gas, the ultrasonic reception voltage is reduced and the propagation time is also reduced. The fluid discriminating means 10 detects the received voltage and the propagation time, discriminates the type of gas from the values, and the circuit constant of the measuring circuit 8 is corrected, for example, by the circuit constant correcting means 11 to correct the amplification degree and the transmission voltage, thereby maintaining the flow rate accuracy. Acts like

(実施の形態2)
図2は、実施の形態2を示したもので計時手段の17の値すなわち超音波の伝搬時間によって流体を判別する。そして流体判別手段10で判別した流体の種類に応じて流量演算手段9で用いられる流量係数を係数補正手段18で補正して流量を正確に算出するものである。流体の種類が変われば流れの状態が変化し、流路7内の流速分布が変わるため流量係数に影響を与えるので流量誤差を生じる。流量係数の値は流体のレイノルズ数に依存するので、流体判別手段によってレイノルズ数を推定すればよい。前述のプロパンガスと水素ガスのように混入されるガスの種類が明らかな場合には、あらかじめ実験により伝搬時間とレイノルズ数との関係を求めておき、マイコンなどに記憶させておけばよい。伝搬時間は流体の温度が変わる変化するので、流体の温度が変化するときには温度検出手段19によって温度を検出し、例えば20℃に換算した伝搬時間で流体の種類を判別する。なお、レイノルズ数は温度によっても変化するので同時に補正することも可能である。
(Embodiment 2)
FIG. 2 shows the second embodiment, and the fluid is discriminated based on the value of 17 of the time measuring means, that is, the propagation time of the ultrasonic wave. The flow rate coefficient used in the flow rate calculation unit 9 is corrected by the coefficient correction unit 18 in accordance with the type of fluid determined by the fluid determination unit 10, and the flow rate is accurately calculated. If the type of fluid changes, the state of the flow changes, and the flow velocity distribution in the flow path 7 changes, which affects the flow coefficient and causes a flow rate error. Since the value of the flow coefficient depends on the Reynolds number of the fluid, the Reynolds number may be estimated by the fluid discrimination means. When the type of gas mixed in, such as propane gas and hydrogen gas described above, is clear, the relationship between the propagation time and the Reynolds number may be obtained in advance by experiments and stored in a microcomputer or the like. Since the propagation time changes as the fluid temperature changes, the temperature is detected by the temperature detection means 19 when the fluid temperature changes, and the type of fluid is determined based on the propagation time converted to, for example, 20 ° C. Since the Reynolds number also changes depending on the temperature, it can be corrected simultaneously.

(実施の形態3)
図3は、実施の形態3を示したもので、流体の種類を受信信号レベルの大きさで判定したもので、実施の形態1で示したプロパンガスに水素ガスが混入した場合にはプロパンガスの受信レベルが流体Aであるのに比べ、水素ガスが混入すると受信レベルが流体Bのように小さくなる。この受信レベルの大きさによって水素ガスがどのくらい混入されているかを推定することができる。
(Embodiment 3)
FIG. 3 shows the third embodiment, in which the type of fluid is determined by the magnitude of the received signal level. When hydrogen gas is mixed into the propane gas shown in the first embodiment, propane gas is used. When the hydrogen gas is mixed, the reception level becomes smaller as in the fluid B than in the fluid A. It can be estimated how much hydrogen gas is mixed by the magnitude of the reception level.

(実施の形態4)
図4は、実施の形態4を示したもので回路定数補正手段11により受信信号の増幅度を前増幅手段19で大きくしたものである。実施の形態4に述べたように水素ガスが混入すると受信レベルが小さくなるので、超音波の受信感度不足を補正する。受信レベルが大きければ前増幅手段19は必要ないのでスリープさせておけばよい。また受信感度を調節す
る別の手段として、回路定数補正手段11により比較手段16のコンパレータ比較信号を切り換えて回路を補正する。図3に示すように受信信号が大きいと予想される流体の時には比較レベルCで動作させ、小さいと予想される流体の時には比較レベルDで動作させるようにする。
(Embodiment 4)
FIG. 4 shows the fourth embodiment, in which the amplification factor of the received signal is increased by the preamplifier 19 by the circuit constant corrector 11. As described in the fourth embodiment, when the hydrogen gas is mixed, the reception level becomes small, so that the lack of ultrasonic reception sensitivity is corrected. If the reception level is high, the pre-amplification means 19 is not necessary, and it is sufficient to sleep. As another means for adjusting the reception sensitivity, the circuit constant correction means 11 switches the comparator comparison signal of the comparison means 16 to correct the circuit. As shown in FIG. 3, when the fluid is expected to have a large received signal, the fluid is operated at the comparison level C, and when the fluid is expected to be small, the fluid is operated at the comparison level D.

(実施の形態5)
図5は実施の形態5を示したもので、回路定数補正手段11により送信手段13を制御する。実施の形態4で述べたように受信感度が小さい流体と予想される場合には、例えばバースト送信の波数を多くするか、あるいは送信電圧を高く設定して適切な超音波信号を得るようにする。
(Embodiment 5)
FIG. 5 shows a fifth embodiment, in which the transmission unit 13 is controlled by the circuit constant correction unit 11. As described in the fourth embodiment, when it is expected that the fluid has low reception sensitivity, for example, the wave number of burst transmission is increased or the transmission voltage is set high to obtain an appropriate ultrasonic signal. .

(実施の形態6)
図6は実施の形態6を示したもので、超音波を受信した後再度送信し、この送受信を複数回繰り返したその総和の時間から流量を算出するシングアラウンド法における実施の形態である。実施の形態3において水素ガスが混入した場合には受信電圧が小さくなるので受信信号に対するノイズの割合が大きくなりS/Nが低下するので計測時間のばらつきが大きくなる。従って実施の形態6では受信電圧が小さくなったことにより流体の種類を判別して繰り返し手段20で繰り返し回数を増加させて流量精度を保つ。
(Embodiment 6)
FIG. 6 shows a sixth embodiment, which is an embodiment in the sing-around method in which an ultrasonic wave is received and then transmitted again, and the flow rate is calculated from the total time of repeating this transmission and reception a plurality of times. In the third embodiment, when hydrogen gas is mixed, the received voltage is reduced, so that the ratio of noise to the received signal is increased and the S / N is reduced, so that the variation in measurement time is increased. Therefore, in the sixth embodiment, the flow rate accuracy is maintained by discriminating the type of fluid due to the decrease in the received voltage and increasing the number of repetitions by the repetition means 20.

(実施の形態7)
図7は実施の形態7を示したもので、前述のシングアラウンド法において受信から送信までの遅延時間を流体の種類に応じて遅延手段21で変化させるものである。シングアラウンド法においては繰り返し超音波を送信するために送受信器5と6間に超音波が反射してノイズとなり正確な超音波の検出を行えなくなる。このため受信して次の超音波を送信するまでに遅延時間を設け反射の影響を低減させる。この遅延時間は流体の性質によって最適値が変わる。したがって流体の種類によって遅延時間をあらかじめ設定しておき、判別した流体の種類に応じた遅延時間を設定する。遅延時間の設定は1マイクロ秒以下の遅延素子を複数回分周させて得るようにすれば、そのカウンタの設定値を変えることで得られる。
(Embodiment 7)
FIG. 7 shows the seventh embodiment, in which the delay time from reception to transmission is changed by the delay means 21 in accordance with the kind of fluid in the above-described sing-around method. In the sing-around method, since ultrasonic waves are repeatedly transmitted, the ultrasonic waves are reflected between the transmitter / receivers 5 and 6 and become noise, so that accurate ultrasonic detection cannot be performed. Therefore, a delay time is provided between reception and transmission of the next ultrasonic wave to reduce the influence of reflection. The optimum delay time varies depending on the properties of the fluid. Therefore, a delay time is set in advance according to the type of fluid, and a delay time corresponding to the determined type of fluid is set. If the delay time is obtained by dividing a delay element of 1 microsecond or less a plurality of times, the delay time can be set by changing the setting value of the counter.

なお本実施の形態ではガスの種類をプロパンガスと水素ガスとの混合ガスについて述べたが、天然ガスにおけるメタンガスとプロパンガスあるいは水素ガスなどの可燃性流体、あるいは可燃性流体と空気との混合流体にも適用できる。   In the present embodiment, the mixed gas of propane gas and hydrogen gas is described as the type of gas. However, a flammable fluid such as methane gas and propane gas or hydrogen gas in natural gas, or a mixed fluid of flammable fluid and air is used. It can also be applied to.

また、混合比と流体の性質はマイクロコンピュータで記憶させる以外に、不揮発性メモリなどで外部から通信手段を介して設定することができる。   Further, the mixing ratio and fluid properties can be set from the outside via a communication means by a non-volatile memory or the like in addition to being stored by a microcomputer.

本発明の実施の形態1の流量計測装置のブロック図1 is a block diagram of a flow rate measuring device according to Embodiment 1 of the present invention. 本発明の実施の形態2の流量計測装置のブロック図Block diagram of a flow rate measuring apparatus according to Embodiment 2 of the present invention 本発明の実施の形態3の流量計測装置の受信信号図Received signal diagram of flow rate measuring apparatus according to embodiment 3 of the present invention 本発明の実施の形態4の流量計測装置のブロック図Block diagram of a flow rate measuring device according to a fourth embodiment of the present invention 本発明の実施の形態5の流量計測装置のブロック図Block diagram of a flow rate measuring device according to a fifth embodiment of the present invention 本発明の実施の形態6の流量計測装置のブロック図Block diagram of a flow rate measuring device according to a sixth embodiment of the present invention 本発明の実施の形態7の流量計測装置のブロック図Block diagram of a flow rate measuring device according to a seventh embodiment of the present invention 従来の流量計測装置のブロック図Block diagram of a conventional flow measurement device

符号の説明Explanation of symbols

5、6 送受信器
8 計測回路
9 流量演算手段
10 流体判別手段
11 回路定数補正手段
13 送信手段
16 比較手段
18 係数補正手段
19 前増幅手段
20 繰り返し手段
21 遅延手段
5, 6 Transceiver 8 Measuring circuit 9 Flow rate calculating means 10 Fluid discriminating means 11 Circuit constant correcting means 13 Transmitting means 16 Comparing means 18 Coefficient correcting means 19 Preamplifying means 20 Repeating means 21 Delay means

Claims (1)

流体中に超音波を送受信する送受信器と、
流れの上流から下流への送信もしくは下流から上流への送信の伝搬時間を計測する計測回路と、
超音波伝搬時間により流量を算出する流量演算手段と、
前記送受信器の信号から前記流路内の流体の種類を判定する流体判別手段と、
前記計測回路の定数を前記流体判別手段で判別した流体の種類に応じて変更する回路定数補正手段とを備えた流量計測装置において、
超音波の受信後に遅延手段を介して再度送信する繰り返し手段と、
この繰り返し送受信の積算時間から流量を算出する繰り返し流量演算手段とを備え、
回路定数補正手段は、流体判別手段で判別した流体の種類に応じて前記遅延手段の設定を変更する流量計側装置。
A transceiver for transmitting and receiving ultrasonic waves in a fluid;
A measurement circuit that measures the propagation time of transmission from upstream to downstream of the flow or transmission from downstream to upstream;
A flow rate calculation means for calculating a flow rate by ultrasonic propagation time;
Fluid discrimination means for determining the type of fluid in the flow path from the signal of the transceiver;
In the flow rate measurement device comprising circuit constant correction means for changing the constant of the measurement circuit according to the type of fluid determined by the fluid determination means,
Repetitive means for transmitting again through delay means after reception of ultrasonic waves;
And a repetitive flow rate calculating means for calculating the flow rate from the accumulated time of this repetitive transmission and reception,
The circuit constant correction unit is a flowmeter side device that changes the setting of the delay unit according to the type of fluid determined by the fluid determination unit.
JP2008263818A 2008-10-10 2008-10-10 Flow measuring device Expired - Lifetime JP4888464B2 (en)

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JPS57119272A (en) * 1981-01-16 1982-07-24 Yokogawa Hokushin Electric Corp Signal detection circuit
JPH053527B2 (en) * 1984-06-22 1993-01-18 Fuji Denki Kk
JPS611169A (en) * 1985-05-24 1986-01-07 Hitachi Ltd Picture reader
JPS6274370A (en) * 1985-09-27 1987-04-06 Yokogawa Electric Corp Gas-liquid discriminating apparatus
JP3374362B2 (en) * 1997-08-06 2003-02-04 矢崎総業株式会社 Gas meter
JP3473341B2 (en) * 1997-08-06 2003-12-02 松下電器産業株式会社 Ultrasonic flow meter
JP3644209B2 (en) * 1997-08-25 2005-04-27 松下電器産業株式会社 Flow measurement control device

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