JPH09318644A - Ultrasonic flow velocity measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely determine the received wave arrival timing and measure the flow velocity with high accuracy by integrating the waves of one or both polarities of the received waves, and setting the time when the integrated output reaches the reference value to the received wave arrival timing for measuring the propagation time difference. SOLUTION: Received waves from transceivers 2, 3 are half-wave shaped by a half-wave shaping circuit 7 through an amplifying circuit 5, and the integrated output from an integrating circuit 8 is compared with the reference voltage from a reference voltage generating circuit 10 by a comparing circuit 9. The reference voltage is set to the middle value where the integrated output rises synchronously with the rise of the half wave of the second wave, thus the integrated output reaches the reference voltage value at the middle time when it rises along the rise of the second wave beyond the peak value of the first wave, and the received wave arrival signal is outputted from the comparing circuit 9 at this time. When the received signal is integrated, the integrated output can be increased in response to the received wave-form, and the first wave of the received wave is not required to be captured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flow velocity measuring method for measuring the flow velocity of gas or other fluid using ultrasonic waves.

[0002]

2. Description of the Related Art In determining the flow rate of a gas or other fluid, the flow rate of the fluid is first measured continuously or periodically, and the flow rate is calculated based on the measured flow rate. I have. As one of such fluid flow velocity measuring methods, a method using ultrasonic waves is known.

FIG. 7 shows the principle of such an ultrasonic flow velocity measuring method.
The description is as follows. In FIG.
(1) is a pipeline through which a fluid such as gas flows in the direction of the arrow. In the pipeline (1), the transducers (2) and (3) are arranged at a predetermined distance upstream and downstream in the flow direction.

Each of the transducers (2) and (3) serves as both a transmitter and a receiver, and includes an ultrasonic transmitting / receiving element (not shown) composed of a vibrator. When the transmitting / receiving element is driven by the driving pulse from the pulse generation circuit (4) and vibrates to generate and transmit an ultrasonic wave, while receiving the transmitted ultrasonic wave and the ultrasonic transmitting / receiving element vibrates. Is output as an electric signal from the amplifier circuit (5).

The propagation time until the ultrasonic wave transmitted from the upstream transducer (2) in the forward direction to the flow is received by the downstream transducer (3), and the downstream The difference between the propagation time until the ultrasonic wave transmitted in the opposite direction to the flow from the transmitter (3) and the ultrasonic wave received by the upstream transducer (2) is related to the flow velocity. , The flow velocity of the fluid is measured.
In FIG. 7, (6) indicates each transducer (2) (3)
And a switching circuit for switching the connection between the pulse generation circuit (4) and the amplification circuit (5). First, the pulse generation circuit (4), the upstream-side transducer (2), and the downstream-side transducer (3) After the amplifier circuit (5) is connected and the propagation time from the upstream side to the downstream side is measured, the pulse generating circuit (4) and the downstream transducer (3) are operated by the operation of the switching circuit (6). The transmission / reception device (2) on the upstream side and the amplifier circuit (5) are switched so as to be connected, and the propagation time from the downstream side to the upstream side is measured. .

[0006] By the way, the propagation time difference of the ultrasonic waves as described above is conventionally based on the first wave of the received wave output from the amplifier circuit (5) via the mutual transducers (2) and (3). Was measured. More specifically, a plurality of rectangular pulses are generally sent from the pulse generation circuit (4) to the ultrasonic transmission element, which causes the ultrasonic transmission element to oscillate in a sinusoidal fashion and to vibrate. The ultrasonic wave corresponding to is output. In the waveform of this ultrasonic wave, the vibration due to the first drive pulse is superposed with the vibration due to the second and third drive pulses, and the peak values of the second wave and the third wave are higher than those of the first wave. , Shows a vibration waveform in which the peak value is gradually attenuated. Therefore, the received waves (W) and (W ′) received by the wave transmitters / receivers (2) and (3) also correspond to the vibration waveforms of the transmitted waves, as shown in FIG. The peak value becomes higher than the second wave (W2) (W2 ′) and the third wave (W3) (W3 ′) than that of ′ ′, and then the peak value is gradually attenuated to become an oscillating waveform.

In the conventional method in which the first waves (W1) and (W1 ') of the received waves (W) and (W') are used for measuring the propagation time difference, the peak value of the first wave is small, The reference voltage for capturing this has no choice but to be small, and there is a drawback in that it is not easy to determine the arrival timing of the received wave that serves as the reference for the propagation time difference.

On the other hand, in order to solve the above-mentioned drawbacks, a curve (envelope) obtained by connecting the peaks of the received waves (W) and (W ') is formed, and the received wave arrives when the envelope reaches the reference voltage. Timing is also done.

However, this method has a drawback that the arrival timing of the received wave fluctuates greatly even when the reference voltage slightly fluctuates due to the gradual inclination of the envelope, and the measurement accuracy is also insufficient. It was

The present invention has been made in view of the above technical background, and it is possible to accurately determine the arrival timing of a received wave for measuring the propagation time difference, and thus to ensure sufficient measurement accuracy. It is intended to provide a method for measuring an acoustic velocity.

[0011]

In order to achieve the above object, one of the present inventions is to arrange a wave transmitter and a wave receiver respectively on the upstream side and the downstream side of a measurement fluid, Propagation of ultrasonic waves obtained by comparing each received wave while applying ultrasonic waves to the ultrasonic wave transmission element of In an ultrasonic flow velocity measuring method for measuring a flow velocity based on a time difference, a wave of one polarity of the received wave or a wave of both polarities obtained by full-wave rectification is integrated, and the time when the integrated output reaches a reference value. Is the reception wave arrival timing for measuring the propagation time difference.

Thus, a value larger than the peak value of the first wave of the received wave can be adopted and set as the reference value. Therefore, it is not necessary to capture the first wave having a small peak value as in the conventional case. Also, instead of setting the received wave arrival timing at the time when the envelope obtained by connecting the peaks of the received wave reaches the reference value, it is possible to compare with the reference value at the rising portion of the integrated output corresponding to the waveform of the received wave, Compared to the envelope method, variation in the reception wave arrival timing when the reference value varies is suppressed.

Another aspect of the present invention is to arrange a wave transmitter and a wave receiver on the upstream side and the downstream side of the measurement fluid, respectively.
A drive pulse was applied to the ultrasonic wave transmitting element of each of the wave transmitters to mutually generate and transmit ultrasonic waves, and the transmitted ultrasonic waves were mutually received by the wave receivers, which were obtained by comparing the received waves. In an ultrasonic flow velocity measuring method for measuring a flow velocity based on a difference in propagation time of the ultrasonic wave, a wave of one polarity of the received wave or a wave of both polarities obtained by full-wave rectification is integrated, and its integrated output is a reference. It is characterized in that the zero cross time point of the received wave after reaching the value is set as the received wave arrival timing for measuring the propagation time difference.

As a result, the zero-cross timing does not change even if the reference value fluctuates to some extent, so that the reception wave arrival timing can be reliably and stably determined.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an ultrasonic flow velocity measuring apparatus for carrying out the invention according to claim 1. FIG.
In Fig. 1, (1) is a pipe line, (2) and (3) are transducers arranged at a predetermined distance on the upstream side and the downstream side in the flow direction, and (4) is a pulse generation circuit for generating a drive pulse,
(5) is an amplifier circuit that outputs the received wave received by the transducers (2) and (3), and (6) is each transducer (2) and (3), a pulse generation circuit (4), and an amplifier circuit (5). ) Is a switching circuit for switching the connection, and these are the same as those shown in FIG. 7.

In this embodiment, on the receiving side, a half-wave rectifier circuit (7) for half-wave rectifying each received wave (W) (W ') from the amplifier circuit (5) and an output of the half-wave rectifier circuit are provided. An integrating circuit (8) for integrating is provided.

Further, a comparison circuit (9) is provided on the output side of the integration circuit (8). This comparison circuit (9)
The output of the integrating circuit (8) is compared with the reference voltage (V) from the reference voltage generating circuit (10), and when the output of the integrating circuit (8) reaches the reference voltage, a reception wave arrival signal is output. Is. If the reference voltage is set to a value lower than the peak value of the first waves (W1) (W1 ') of the received waves (W) (W'), it becomes the same as the conventional method of capturing the first waves. Therefore, it is necessary to set the value higher than the peak value of the first wave. In this embodiment, the reference voltage (V) is set so that the integrated output reaches the reference voltage (V) while the integrated output rises in synchronization with the rising of the second wave (W2) (W2 ′). There is.

In the apparatus shown in FIG. 1, a transmitter / receiver (2) on the upstream side of the fluid sends a transmitter wave having a desired waveform,
This is received by the wave transmitter / receiver (3) on the downstream side, and a received wave (W) as shown in FIG. 2 is obtained through the amplifier circuit (5),
Immediately, the connection is switched by the switching circuit (6), the transmission wave of the desired waveform is sent from the downstream side transducer (3), and this is received by the upstream side transducer (2). The received wave (W ') as shown is obtained via the amplifier circuit (5). These received waves (W) and (W ') are, as shown in the figure, the second waves (W2) and (W2) rather than the first waves (W1) and (W1').
′), The third wave (W3) (W3 ′), and the peak value becomes higher, and then the vibration waveform becomes such that the peak value is gradually attenuated.

These received waves (W) and (W ') are half-wave rectified by the half-wave rectifier circuit (7) to become waves of positive polarity as shown in FIG. 3, which are further integrated by the integrating circuit (8). As shown in FIG. 4, the integrated output of the integrating circuit (8) has a step-like waveform in which the peak value sequentially increases corresponding to the first, second, third, ... Half waves.

Next, a comparison circuit (9) compares the integrated output of the integration circuit (8) as described above with the reference voltage (V) from the reference voltage generation circuit (10). In this embodiment, the reference voltage (V) is set to a value during which the integrated output rises in synchronization with the rising of the half wave of the second wave, so that the integrated output exceeds the peak value of the first wave and The reference voltage value (V) is reached at a time T1 during the rising of the two waves. Then, at that time, the received wave arrival signal is output from the comparison circuit (9). In this way, by integrating the received waves (W) and (W ′), the integrated output can be increased in a form corresponding to the received waveform.
It is not necessary to capture the first wave (W1) (W1 ') of the received waves (W) (W').

Thus, the two received waves (W) (W ') are
Since there is a propagation time difference (phase difference) that changes according to the fluid flow velocity, the arrival signal of the received wave received on the upstream side is
It is output at time T2 after transmission. Therefore, the time difference (T2-T1) between the two received wave arrival signals becomes the propagation time difference, which is measured, the fluid flow velocity is obtained based on this, and the flow rate is obtained if necessary. When it is necessary to measure the fluid flow velocity continuously or periodically, the above operation may be repeated continuously or periodically at predetermined intervals.

FIG. 5 shows a measuring apparatus for carrying out the invention of claim 2. In this embodiment, a zero cross detection circuit (11) is provided on the output side of the comparison circuit (9),
Immediately after the signal is output from the comparison circuit (9), the zero cross of the received wave output from the amplifier circuit (5) is detected at the timing of arrival time T1'T2 ', and this is used as the received wave arrival timing. is there. By doing so, even if the reference voltage (V) from the reference voltage generation circuit (10) changes, the zero-cross timing does not change, so that the arrival timing of the received wave does not change, and therefore the accuracy is even higher. Flow velocity measurement can be performed.

In the embodiments shown in FIGS. 5 and 6, the same components as those shown in FIG. 1 are designated by the same names and reference numerals, and the description thereof will be omitted.

In the above embodiment, the case where only the wave of one polarity is integrated by rectifying the received wave by half wave is shown. However, the wave of both polarities of the received wave is obtained by rectifying the received wave by full wave. May be integrated. Also, one wave transmitter / receiver is provided on each of the upstream side and the downstream side of the fluid flow, and the connection is switched by the switching circuit to sequentially perform transmission from the upstream side to the downstream side and transmission from the downstream side to the upstream side. Although the case was shown, the propagation time can be measured by installing the wave transmitter and the wave receiver separately on the upstream side and the wave receiver and the wave transmitter separately on the downstream side. It may be performed simultaneously.

[0025]

According to the first aspect of the present invention,
Since the wave of one polarity of the received wave or the wave of both polarities that is full-wave rectified is integrated and the time when the integrated output reaches the reference value is the received wave arrival timing for measuring the propagation time difference, the received wave A value larger than the peak value of the first wave can be adopted and set as the reference value. Therefore, it is not necessary to capture the first wave having a small peak value as in the conventional case, and the arrival timing of the received wave can be reliably determined. Moreover, instead of setting the reception wave arrival timing at the time when the envelope obtained by connecting the peaks of the reception wave reaches the reference value, it is possible to compare with the reference value at the rising portion of the integrated output corresponding to the waveform of the reception wave. Compared with the envelope method, it is possible to suppress the variation of the reception wave arrival timing when the reference value varies, the timing can be determined with high accuracy, and it is possible to measure the flow velocity with high accuracy.

According to a second aspect of the present invention, a received wave having one polarity or a full-wave rectified wave having both polarities is integrated, and the zero crossing of the received wave after the integrated output reaches a reference value. The time point is used as the reception wave arrival timing for measuring the propagation time difference. Therefore, even if the reference value fluctuates to some extent, the zero-cross timing does not fluctuate, so that the arrival timing of the received wave can be reliably and stably determined, and the flow velocity can be measured with higher accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an ultrasonic flow velocity measuring device for carrying out the invention of claim 1;

FIG. 2 is a waveform diagram of two received waves output from the amplifier circuit of the device of FIG.

FIG. 3 is an output waveform diagram of the half-wave rectifier circuit.

FIG. 4 is an output waveform diagram of the integration circuit.

FIG. 5 is a block diagram showing an example of an ultrasonic flow velocity measuring apparatus for carrying out the invention of claim 2.

FIG. 6 is an output waveform diagram of an integrating circuit of the apparatus of FIG.

FIG. 7 is a block diagram showing an example of an ultrasonic flow velocity measuring device for performing a conventional method.

[Explanation of symbols]

 1 ... Piping 2, 3 ... Transceiver 4 ... Pulse generation circuit 5 ... Amplification circuit 6 ... Switching circuit 7 ... Half-wave rectification circuit 8 ... Integration circuit 9 ... Comparison circuit 10 ... Reference voltage generation circuit 11 ... Zero cross detection circuit W, W '... received wave

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akio Tomita 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi Inside Osaka Gas Co., Ltd. Inside Kansai Gas Meter Co., Ltd. (72) Eiji Nakamura Inventor Kansai Gas Meter Co., Ltd. 2- 10-16 Higashi Kobashi, Higashi-Nari-ku, Osaka City

Claims (2)

[Claims] 1. A transmitter and a receiver are arranged on an upstream side and a downstream side of a measurement fluid, respectively, and a driving pulse is applied to an ultrasonic transmitting element of each of the transmitters to generate and transmit ultrasonic waves mutually. While receiving the transmitted ultrasonic waves with each other,
In the ultrasonic flow velocity measuring method for measuring the flow velocity based on the difference in the propagation time of the ultrasonic wave obtained from the comparison of the respective received waves, a wave of one polarity of the received wave or a wave of both polarities full-wave rectified An ultrasonic flow velocity measuring method, characterized by integrating and using a time point when the integrated output reaches a reference value as a received wave arrival timing for measuring a propagation time difference. 2. A wave transmitter and a wave receiver are respectively arranged on the upstream side and the downstream side of a measurement fluid, and a drive pulse is applied to an ultrasonic wave transmitting element of each wave transmitter to mutually generate and transmit ultrasonic waves. In addition, the transmitted ultrasonic waves are mutually received by the receiver,
In the ultrasonic flow velocity measuring method for measuring the flow velocity based on the difference in the propagation time of the ultrasonic wave obtained from the comparison of the respective received waves, a wave of one polarity of the received wave or a wave of both polarities full-wave rectified An ultrasonic flow velocity measuring method, characterized in that the zero crossing point of the received wave after the integration is reached and the integrated output reaches a reference value is set as the received wave arrival timing for measuring the propagation time difference.