WO2022059540A1 - 伝搬時間測定装置 - Google Patents

伝搬時間測定装置 Download PDF

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Publication number
WO2022059540A1
WO2022059540A1 PCT/JP2021/032623 JP2021032623W WO2022059540A1 WO 2022059540 A1 WO2022059540 A1 WO 2022059540A1 JP 2021032623 W JP2021032623 W JP 2021032623W WO 2022059540 A1 WO2022059540 A1 WO 2022059540A1
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Prior art keywords
signal
oscillator
propagation time
input
measuring device
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PCT/JP2021/032623
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English (en)
French (fr)
Japanese (ja)
Inventor
将貴 矢和田
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オムロン株式会社
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Publication of WO2022059540A1 publication Critical patent/WO2022059540A1/ja

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters

Definitions

  • the present invention relates to a technique for measuring the propagation time of an acoustic signal.
  • a device that can measure the propagation time of an acoustic signal propagating inside a pipe by a sensor attached to the outside of the pipe and can measure the flow velocity and flow rate of the fluid flowing in the pipe in a non-destructive manner based on the propagation time has been put into practical use.
  • This type of device generally uses ultrasonic waves as an acoustic signal, and is called an “ultrasonic flow meter” or an “ultrasonic flow meter”.
  • Patent Document 1 a pair of ultrasonic oscillators arranged on the upstream side and the downstream side of a pipe are used to propagate the ultrasonic waves propagating in the forward direction and the ultrasonic waves propagating in the opposite direction of the fluid flow.
  • a device for determining the flow rate of a fluid based on a time difference is disclosed.
  • the propagation time difference is calculated by calculating the correlation function between the received signal of the ultrasonic vibrator on the upstream side and the received signal of the ultrasonic vibrator on the downstream side.
  • the signal propagation time may not be accurately measured due to the influence of jitter (fluctuation of signal waveform in the time axis direction) and delay generated in electric circuits such as A / D converters and amplifiers. There is. Therefore, the conventional ultrasonic flow meter cannot be used for applications requiring high accuracy such as measurement of minute flow rate.
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique capable of suppressing the influence of jitter and delay and measuring the propagation time with high accuracy. ..
  • the propagation time measuring device is a plurality of oscillators arranged at different positions with respect to a pipe through which a fluid flows, and includes a first oscillator that converts a transmission signal as an electric signal into an acoustic signal, and the above-mentioned.
  • a plurality of oscillators including at least a second oscillator that receives the acoustic signal transmitted from the first oscillator and propagates through the fluid in the pipe and converts it into a received signal as an electric signal, and the second vibration.
  • a signal processing unit for obtaining a propagation time of the acoustic signal from the first oscillator to the second oscillator based on the transmitted signal and the received signal converted into digital signals by a converter is provided.
  • the transmission signal input to the first oscillator is branched and input to the analog-digital converter to which the reception signal output from the second oscillator is input. Since the received signal and the transmitted signal are input to a single analog-digital converter, the jitter generated when the transmitted signal is converted from the analog signal to the digital signal and the jitter generated when the received signal is converted from the analog signal to the digital signal are generated. The jitter will be approximately the same or similar. Therefore, when the propagation time of the acoustic signal is obtained, the reference time of the transmission signal and the reference time of the reception signal are substantially matched or approximated, and the influence of jitter can be reduced. Further, the transmission signal and the reception signal are A / D converted by a single analog-to-digital converter.
  • the delay time of the transmission signal due to A / D conversion that is, the time required for A / D conversion of the transmission signal and the delay time of the reception signal due to A / D conversion, that is, the reception signal is A / D converted. It will be approximately the same as or close to the time required for. Therefore, it is possible to suppress the influence of signal delay due to A / D conversion on the measurement of the propagation time of the acoustic signal.
  • the propagation time measuring device is provided on the bypass line, and may include an attenuator that attenuates the transmission signal propagating on the bypass line. If the signal level of the transmission signal propagating on the bypass line is high, the signal level of the transmission signal input to the analog-to-digital converter may be out of the measurement range of the analog-to-digital converter. By attenuating the transmission signal propagating through the bypass line by the attenuator, the signal level of the transmission signal input to the analog-to-digital converter is within the measurement range of the analog-to-digital converter.
  • the attenuator may be composed of a passive element.
  • passive elements such as resistors and capacitors
  • the delay time of the transmitted signal when attenuating the transmitted signal propagating through the bypass line, that is, the time required for the attenuator to attenuate the transmitted signal is small. It becomes.
  • the propagation time measuring device may further include an amplifier provided between the second oscillator and the analog-to-digital converter and amplifying the transmission signal and the reception signal input to the analog-digital converter. .. Since the acoustic signal is attenuated when the acoustic signal propagates through the fluid in the pipe, the signal level of the received signal becomes smaller when the second oscillator converts the acoustic signal into the received signal, which makes it an analog-digital converter. The signal level of the input received signal may be outside the measurement range of the analog-digital converter. By amplifying the received signal by the amplifier, the signal level of the received signal input to the analog-to-digital converter is within the measurement range of the analog-to-digital converter.
  • the bypass line may be connected to a signal line between the second oscillator and the amplifier.
  • the transmission signal input to the first oscillator and the reception signal output from the second oscillator are input to the amplifier via the signal line. Therefore, the delay time of the transmission signal when amplifying the transmission signal, that is, the time required to amplify the transmission signal and the delay time of the reception signal when amplifying the reception signal, that is, to amplify the reception signal. It is almost the same as the time required. In this way, since the transmitted signal and the received signal are delayed by the same amplifier, the influence of the signal delay by the amplifier on the measurement of the propagation time of the acoustic signal can be suppressed. That is, in the measurement of the propagation time of the acoustic signal, the influence of the signal delay by the amplifier can be ignored.
  • the propagation time measuring device is provided between a transmission signal generator that generates the transmission signal, the transmission signal generator, and the first oscillator, and amplifies the transmission signal input to the first oscillator.
  • a second amplifier may be further provided. Since the acoustic signal is attenuated when the acoustic signal propagates through the fluid in the pipe, the signal level of the received signal output by the second oscillator can be increased by amplifying the transmission signal input to the first oscillator. Can be made larger. As a result, the signal level of the received signal input to the analog-to-digital converter is within the measurement range of the analog-to-digital converter.
  • the bypass line may be connected to a signal line between the second amplifier and the first oscillator.
  • the transmission signal amplified by the second amplifier is input to the first oscillator, branched by the bypass line, and input to the analog-to-digital converter.
  • the first oscillator converts the amplified transmission signal into an acoustic signal
  • the second oscillator receives the acoustic signal and outputs the received signal. Therefore, the transmission signal branched by the bypass line and input to the analog-to-digital converter and the transmission signal output from the second oscillator and input to the analog-to-digital converter have a delay in amplification by the same second amplifier.
  • the first oscillator and the second oscillator may be arranged so as to face each other with the pipe interposed therebetween. Further, the first oscillator and the second oscillator may be arranged at different positions in the longitudinal direction of the pipe.
  • the transmitted signal is input to the second oscillator, and the received signal output from the first oscillator that has received the acoustic signal transmitted from the second oscillator and the bypass line.
  • a switching unit for switching the transmission signal branched via the above to be input to the analog digital converter is provided, and the signal processing unit is the transmission converted into a digital signal by the analog digital converter.
  • the propagation time of the acoustic signal from the second oscillator to the first oscillator may be obtained based on the signal and the received signal.
  • the propagation time when the acoustic signal propagates from the upstream side to the downstream side and the propagation time when the acoustic signal propagates from the downstream side to the upstream side are accurately obtained for the same propagation path. be able to.
  • the signal processing unit determines the difference between the propagation time of the acoustic signal from the first oscillator to the second oscillator and the propagation time of the acoustic signal from the second oscillator to the first oscillator. Based on this, the flow velocity and / or flow rate of the fluid in the pipe may be obtained. This makes it possible to measure the information of the fluid in the pipe with high accuracy.
  • the present invention may be regarded as a propagation time measuring device having at least a part of the above configuration, may be regarded as a flow velocity measuring device, a flow rate measuring device, a flow meter, a flow rate sensor, or the like, or may be regarded as a transmission for generating a transmission signal. It may be regarded as a signal generator, a transmission circuit, or the like. Further, the present invention may be regarded as a propagation time measuring method, a flow velocity measuring method, a flow rate measuring method, a transmission signal generation method including at least a part of the above processing, or a program for realizing such a method or a program thereof. Can also be regarded as a recording medium for recording non-temporarily. The present invention can be configured by combining each of the above configurations and treatments with each other as much as possible.
  • FIG. 1 is a diagram schematically showing a configuration of a propagation time measuring device.
  • FIG. 2 is a cross-sectional view showing an example of installing an oscillator in a pipe.
  • FIG. 3 is a diagram showing an example of an attenuator.
  • FIG. 4 is a flowchart showing a flow of measurement operation of the propagation time measuring device according to the first embodiment.
  • FIG. 5 is a time chart of a control signal, a transmission signal, and a reception signal.
  • the propagation time measuring device 1 includes two or more oscillators 101, receives an acoustic signal transmitted from one of the oscillators (for example, 101a) by another oscillator (for example, 101b), and receives the acoustic signal between the two oscillators.
  • the time required for the acoustic signal to propagate through the path is measured. Since the oscillators 101 are arranged at different positions with respect to the pipe 120, the acoustic signal propagating between the two oscillators 101 passes (crosses) the inside of the pipe 120.
  • the propagation time of the acoustic signal is not constant and changes depending on the state of the fluid 121 flowing in the pipe 120 (for example, the flow velocity, the flow rate, the presence of bubbles or foreign matter, etc.). Therefore, by using the propagation time measured by the propagation time measuring device 1, the state of the fluid 121 in the pipe 120 can be measured non-destructively.
  • the fluid 121 may be a liquid or a gas as long as it is a substance capable of propagating an acoustic signal.
  • the acoustic signal is typically ultrasonic, but may include sound waves in the audible range.
  • the propagation time measuring device 1 transmits.
  • the received signal is acquired together with the transmitted signal from the common signal line through which the signal and the received signal propagate.
  • the propagation time measuring device 1 obtains a lag (time delay) of the received signal with respect to the transmitted signal based on the acquired transmission signal and reception signal. This lag corresponds to the propagation time of the acoustic signal from the oscillator 101 on the transmitting side to the oscillator 101 on the receiving side.
  • first oscillator 101a first oscillator 101a
  • second oscillator 101b second oscillator 101b
  • the propagation time measuring device 1 is connected to the signal line 201a connected to the first oscillator 101a on the transmitting side, the signal line 201b connected to the second oscillator 101b on the receiving side, and the signal line 201a and the signal line 201b. It is provided with a bypass line 201c. One end of the signal line 201a is connected to the first oscillator 101a, and the other end of the signal line 201a is connected to the switch 105. One end of the signal line 201b is connected to the second oscillator 101b, and the other end of the signal line 201b is connected to the switch 105.
  • the switch 105 switches so that the transmission signal is input to the second oscillator 101b and the reception signal is output from the first oscillator 101a that has received the acoustic signal transmitted from the second oscillator.
  • the second oscillator 101b becomes the transmitting side
  • the first oscillator 101a becomes the receiving side.
  • the transmission signal generator 103 and the A / D (analog-digital) converter 104 are connected to the switch 105.
  • the transmission signal generator 103 generates a transmission signal and outputs the transmission signal to the signal line 201d connecting the transmission signal generator 103 and the switching device 105.
  • the transmission signal output to the signal line 201d propagates through the signal line 201a connected to the switch 105 and is input to the first oscillator 101a.
  • the received signal output from the second oscillator 101b propagates through the signal line 201b and the signal line 201e connecting the A / D converter 104 and the switch 105, and is input to the A / D converter 104.
  • the bypass line 201c branches the transmission signal input to the first oscillator 101a and guides it to the input of the A / D converter 104.
  • the transmission signal generated by the transmission signal generator 103 is input to the first oscillator 101a and also to the A / D converter 104.
  • the transmission signal and the reception signal input to the A / D converter 104 are converted from an analog signal to a digital signal and output to the signal processing unit 111.
  • the signal processing unit 111 obtains the propagation time of the acoustic signal from the first oscillator 101a to the second oscillator 101b based on the transmission signal and the reception signal converted into digital signals.
  • the jitter generated when the transmission signal is converted from the analog signal to the digital signal and the reception signal are analog.
  • the jitter that occurs when converting a signal to a digital signal can be very different. Jitter is the position variation of the signal edge from ideal timing in a periodic signal, and if the signal has jitter, the reference time of the signal will vary. Therefore, when the jitter of the transmission signal and the jitter of the reception signal are significantly different, the reference time of the transmission signal and the reference time of the reception signal when measuring the propagation time of the acoustic signal cannot be matched.
  • the propagation time measuring device 1 branches and inputs the transmission signal input to the first oscillator 101a to the A / D converter 104 to which the reception signal output from the second oscillator 101b is input. Since the received signal and the transmitted signal are input to a single A / D converter 104, the jitter generated when the transmitted signal is converted from the analog signal to the digital signal and when the received signal is converted from the analog signal to the digital signal. It will be almost the same as or close to the jitter generated in. Therefore, the reference time of the transmission signal when measuring the propagation time of the acoustic signal and the reference time of the received signal can be substantially matched or approximated, and the influence of jitter when measuring the propagation time of the acoustic signal is reduced. be able to.
  • FIG. 1 is a block diagram schematically showing the configuration of the propagation time measuring device 1
  • FIG. 2 is a cross-sectional view showing an example of installing an oscillator in a pipe.
  • the propagation time measuring device 1 of the present embodiment is a device for measuring the flow velocity and the flow rate of the fluid 121 flowing in the pipe 120 in a non-destructive manner, and is also referred to as an ultrasonic flow meter or an ultrasonic flow sensor.
  • the propagation time measuring device 1 has a device main body 100 and a plurality of oscillators 101.
  • the apparatus main body 100 and the first oscillator 101a are connected by a signal line 201a, and the apparatus main body 100 and the second oscillator 101b are connected by a signal line 201b.
  • two oscillators 101 are provided, a first oscillator 101a arranged on the upstream side in the longitudinal direction of the pipe 120 and a second oscillator 101b arranged on the downstream side of the first oscillator 101a.
  • the number of oscillators 101 is not limited to two, and three or more oscillators 101 may be provided in the pipe 120.
  • the oscillator 101 is a device that mutually converts an electric signal and an acoustic signal, and is also called a transducer.
  • the oscillator 101 for example, a piezoelectric element that mutually converts voltage and force by the piezo effect can be used.
  • each oscillator 101 is embedded in a clamp 30 made of resin or the like.
  • the two oscillators 101 face each other with the pipe 120 in between, and the straight line connecting the two oscillators 101 (101a, 101b) is with respect to the axis of the pipe 120.
  • the first oscillator 101a and the second oscillator 101b are installed so as to form a predetermined angle ⁇ .
  • the oscillator 101 can be easily attached to the existing pipe 120 (and without modifying the pipe 120) at an appropriate position. It is preferable that grease or gel is applied between the clamp 30 and the pipe 120 in order to bring the clamp 30 and the pipe 120 into close contact with each other and to match the acoustic impedance.
  • the angle ⁇ is called the propagation angle of the acoustic signal.
  • the propagation angle ⁇ is arbitrary, but when the propagation time difference method described later is used, it may be set in the range of 0 degrees ⁇ ⁇ 90 degrees, preferably 20 degrees ⁇ ⁇ 60 degrees.
  • the device main body 100 includes a control circuit 102, a transmission signal generator 103, an A / D converter 104, a switch 105, and an output device 106.
  • the control circuit 102 is a circuit that controls each part of the propagation time measuring device 1, performs signal processing, arithmetic processing, and the like.
  • the transmission signal generator 103 is a circuit that generates a transmission signal (analog signal) having a predetermined voltage based on a control signal (trigger signal) input from the control circuit 102 and outputs the transmission signal (analog signal) to the signal line 201d.
  • the switch 105 is a switch that switches between the input destination of the transmission signal and the output source of the received signal based on the switching signal input from the control circuit 102.
  • the switch 105 switches the connection relationship between the signal lines 201a and 201b and the signal lines 201d and 201e.
  • a transmission signal is input to the second oscillator 101b, and the reception signal output from the first oscillator 101a that has received the acoustic signal transmitted from the second oscillator 101b is branched via the bypass line 201c. Switching is performed so that the transmitted signal and the transmitted signal are input to the A / D converter 104.
  • the second oscillator 101b becomes the transmitting side
  • the first oscillator 101a becomes the receiving side.
  • the output device 106 is a device that outputs information such as the results of signal processing and arithmetic processing by the control circuit 102, and is, for example, a display device.
  • the device main body 100 is provided with an input unit (for example, a button, a touch panel, etc.) for the user to operate, or a communication circuit (for example, a WiFi module) for transmitting information to an external device (for example, an external computer or a server). Etc.) may be provided.
  • the control circuit 102 has a signal processing unit 111 and a storage unit 112.
  • the signal processing unit 111 has a function of calculating the propagation time of the acoustic signal based on the transmission signal and the reception signal, and further calculating the flow velocity and / or the flow rate of the fluid 121 from the propagation time.
  • the storage unit 112 stores the propagation time of the acoustic signal calculated by the signal processing unit 111, the flow velocity and / or the flow rate of the fluid 121, and the like. Further, the storage unit 112 stores data necessary for the signal processing unit 111 to perform a calculation.
  • the control circuit 102 may be configured by, for example, a computer having a CPU (processor), RAM, a non-volatile storage device (for example, ROM, flash memory, hard disk, etc.), I / O, and the like.
  • the CPU expands the program stored in the storage device into the RAM and executes the program, thereby providing the function of the signal processing unit 111.
  • the form of the computer does not matter. For example, it may be a personal computer, an embedded computer, a smartphone, a tablet terminal, or the like.
  • all or part of the functions provided by the control circuit 102 may be configured by a circuit such as an ASIC or FPGA.
  • the control circuit 102 may perform the processing described later in cooperation with another computer by using the technology of distributed computing or cloud computing.
  • the material, size, and shape of the pipe 120 do not matter.
  • metal piping or resin piping may be used.
  • the size of the pipe 120 may be a standard size defined by JIS or ANSI, or may be a unique size. Since the method of this embodiment has an advantage that a minute flow rate can be measured with high accuracy, it is suitable for measuring small pipes such as 1/8 inch pipe, 1/4 inch pipe, and 1/2 inch pipe. It is particularly preferably applicable.
  • the pipe is not limited to a straight pipe, but may be a pipe having a bent portion, a curved pipe, or the like, and the cross-sectional shape of the pipe is arbitrary.
  • the reference time of the transmission signal and the reference time of the reception signal when measuring the propagation time of the acoustic signal cannot be matched.
  • the transmission signal generated by the transmission signal generator 103 propagates from the signal line 201d to the signal line 201a and is input to the first oscillator 101a.
  • the transmission signal generated by the transmission signal generator 103 branches from the signal line 201a, propagates through the bypass line 201c, the signal lines 201b and 201e, and is input to the A / D converter 104.
  • the received signal output from the second oscillator 101b propagates through the signal lines 201b and 201e and is input to the A / D converter 104. Since the transmission signal and the reception signal are input to the A / D converter 104 via the signal lines 201b and 201e, the jitter generated when the transmission signal propagates through the signal lines 201b and 201e and the reception signal are the signal lines.
  • the jitter generated when propagating 201b and 201e is substantially the same or similar.
  • the reference time of the transmission signal when measuring the propagation time of the acoustic signal and the reference time of the received signal can be substantially matched or approximated, and the influence of jitter when measuring the propagation time of the acoustic signal is reduced. be able to.
  • the amplifier 301 is provided on the signal line 201e connecting the A / D converter 104 and the switch 105.
  • the amplifier 301 provided between the second oscillator 101b and the A / D converter 104 inputs to the A / D converter 104. Amplifies the transmitted signal and the received signal. That is, the amplifier 301 amplifies the transmission signal and the reception signal propagating on the signal line 201e and outputs them to the A / D converter 104.
  • the A / D converter 104 converts the transmission signal and the reception signal amplified by the amplifier 301 from an analog signal to a digital signal.
  • the signal level of the received signal may be small when the second oscillator 101b converts the acoustic signal into the received signal. Therefore, the signal level of the received signal input to the A / D converter 104 may be out of the measurement range of the A / D converter 104.
  • the signal level of the received signal input to the A / D converter 104 can be kept within the measurement range of the A / D converter 104.
  • the amplifier 302 is provided on the signal line 201d connecting the transmission signal generator 103 and the switch 105.
  • the amplifier 302 provided between the first oscillator 101a and the transmission signal generator 103 is input to the first oscillator 101a.
  • Amplifies the transmitted signal That is, the amplifier 302 amplifies the transmission signal generated by the transmission signal generator 103, propagated from the signal line 201d to the signal line 201a, and input to the first oscillator 101a.
  • the amplifier 302 is an example of a second amplifier.
  • the reception signal output by the second oscillator 101b is output by amplifying the transmission signal input to the first oscillator 101a.
  • the signal level of can be increased.
  • the signal level of the received signal input to the A / D converter 104 can be kept within the measurement range of the A / D converter 104.
  • the transmission signal amplified by the amplifier 302 is input to the first oscillator 101a, branched by the bypass line 201c, and input to the A / D converter 104.
  • the first oscillator 101a converts the amplified transmission signal into an acoustic signal
  • the second oscillator 101b receives the acoustic signal and outputs the received signal. Therefore, the transmission signal branched by the bypass line 201c and input to the A / D converter 104 and the transmission signal output from the second transducer 101b and input to the A / D converter 104 are the same amplifier 302.
  • the influence of the signal delay by the amplifier 302 on the measurement of the propagation time of the acoustic signal can be suppressed. That is, in measuring the propagation time of the acoustic signal, the influence of the signal delay by the amplifier 302 can be ignored.
  • the attenuator 303 is provided on the signal line 201a and the bypass line 201c connected to the signal line 201b.
  • the attenuator 303 attenuates the transmission signal propagating on the bypass line 201c.
  • the transmitted signal attenuated by the attenuator 303 propagates through the bypass lines 201c, the signal lines 201b, and 201e and is input to the A / D converter 104. Due to the high signal level of the transmission signal propagating on the bypass line 201c, the signal level of the transmission signal input to the A / D converter 104 may be out of the measurement range of the A / D converter 104.
  • the signal level of the transmission signal input to the A / D converter 104 can be kept within the measurement range of the A / D converter 104.
  • the bypass line 201c is connected to the signal line 201b between the first oscillator 101b and the amplifier 301.
  • the transmission signal input to the first oscillator 101a and the reception signal output from the second oscillator 101b are input to the amplifier 301 via the signal line 201b.
  • the delay time of the transmission signal when amplifying the transmission signal that is, the time required to amplify the transmission signal and the delay time of the reception signal when amplifying the reception signal, that is, to amplify the reception signal. It is almost the same as the time required. In this way, since the transmission signal and the reception signal are delayed by the same amplifier 301, the influence of the signal delay by the amplifier 301 on the measurement of the propagation time of the acoustic signal can be suppressed. That is, in measuring the propagation time of the acoustic signal, the influence of the signal delay by the amplifier 301 can be ignored.
  • the attenuator 303 may be composed of a passive element.
  • the attenuator 303 shown in FIG. 3 is composed of capacitors 401 and 402 and resistors 403, 404 and 405.
  • the delay time of the transmission signal (the time required for the attenuator 303 to attenuate the transmission signal) when attenuating the transmission signal propagating on the bypass line 201c is minimized. Can be done.
  • step S100 the control circuit 102 controls the switch 105 so that the transmission signal is input from the signal line 201a to the first oscillator 101a and the reception signal is output from the second oscillator 101b to the signal line 201b. .. As a result, the first oscillator 101a becomes the transmitting side and the second oscillator 101b becomes the receiving side.
  • step S101 the control circuit 102 outputs a control signal to the transmission signal generator 103 and the A / D converter 104, and the transmission signal generator 103 is determined based on the control signal input from the control circuit 102.
  • a voltage transmission signal (analog signal) is generated and output to the signal line 201d.
  • the transmission signal output from the transmission signal generator 103 is amplified by the amplifier 302 and input to the signal line 201a.
  • step S102 the transmission signal propagates through the signal line 201a and is input to the first oscillator 101a, and the first oscillator 101a outputs an acoustic signal based on the transmission signal.
  • the acoustic signal reaches the second oscillator 101b via the clamp 30, the pipe 120, and the fluid 121.
  • step S103 the transmission signal propagating the signal line 201a branches, propagates through the bypass lines 201c, the signal lines 201b, and 201e, and is input to the A / D converter 104.
  • the transmission signal propagating on the bypass line 201c is attenuated by the attenuator 303, amplified by the amplifier 301, and then input to the A / D converter 104.
  • step S104 the A / D converter 104 converts the transmission signal from a digital signal to an analog signal and outputs the transmission signal to the control circuit 102.
  • the transmission signal A / D converted by the A / D converter 104 is taken in by the control circuit 102 and stored in the storage unit 112.
  • the second oscillator 101b receives the acoustic signal, converts the acoustic signal into a received signal, and outputs the acoustic signal to the signal line 201b. Since the acoustic signal is attenuated in the propagation process, the amplitude (voltage) of the received signal is on the order of 1/100 to 1/1000 of that of the transmitted signal.
  • the received signal propagates through the signal lines 201b and 201e and is input to the A / D converter 104. The received signal propagating through the signal line 201e is amplified by the amplifier 301 and then input to the A / D converter 104.
  • step S107 the A / D converter 104 converts the received signal from a digital signal to an analog signal and outputs the received signal to the control circuit 102.
  • the received signal A / D converted by the A / D converter 104 is taken in by the control circuit 102 and stored in the storage unit 112.
  • step S108 the signal processing unit 111 reads the transmission signal and the reception signal from the storage unit 112, and calculates the propagation time of the acoustic signal.
  • step S109 the control circuit 102 controls the switch 105, a transmission signal is input to the second oscillator 101b, and an acoustic signal transmitted from the second oscillator 101b is output from the first oscillator 101a. Switching is performed so that the received signal and the transmitted signal branched via the bypass line 201c are input to the A / D converter 104. That is, by exchanging the oscillator 101 on the transmitting side and the oscillator 101 on the receiving side, the second oscillator 101b becomes the transmitting side and the first oscillator 101a becomes the receiving side.
  • steps S110 to S117 are the same as the processes of steps S101 to S108 (however, “first oscillator 101a” is read as “second oscillator 101b", and “second oscillator 101b” is ". It should be read as "first oscillator 101a”.)
  • the propagation time Tab of the acoustic signal from the first oscillator 101a to the second oscillator 101b and the propagation time Tba of the acoustic signal from the second oscillator 101b to the first oscillator 101a can be obtained.
  • a time difference is generated between the propagation times Tab and Tba according to the flow velocity of the fluid 121. Therefore, the flow velocity and the flow rate of the fluid 121 can be calculated by using the propagation times Tab and Tba.
  • step S118 the signal processing unit 111 obtains the flow velocity V of the fluid 121 by the following formula.
  • V is the flow velocity of the fluid
  • L is the propagation path length inside the pipe
  • ⁇ is the propagation angle
  • Tab is the propagation time from the upstream oscillator to the downstream oscillator
  • Tba is upstream from the downstream oscillator.
  • To is the propagation time of the part other than the fluid.
  • the propagation time To of the portion other than the fluid is, for example, the time during which the acoustic signal propagates through the portion of the clamp 30 and the pipe 120, and if the specifications of the pipe 120 (inner diameter, outer diameter, material, etc.) are known, an experiment is performed. Alternatively, it can be obtained in advance by simulation.
  • step S119 the signal processing unit 111 obtains the fluid flow rate Q by the following equation.
  • Q is the flow rate of the fluid
  • V is the flow velocity of the fluid
  • A is the cross-sectional area inside the pipe. It is assumed that the cross-sectional area A is known.
  • the flow velocity V may be corrected by a correction coefficient.
  • the signal processing unit 111 may calculate the flow velocity V'by dividing the flow velocity V by the correction coefficient, and may obtain the flow rate Q of the fluid by the above formula using the flow velocity V'instead of the flow velocity V.
  • step S120 the signal processing unit 111 outputs the processing result (for example, propagation time, flow velocity, flow rate, etc.) to the output device 106.
  • the processing result for example, propagation time, flow velocity, flow rate, etc.
  • the transmission signal input to the first oscillator 101a is branched to the A / D converter 104 to which the reception signal output from the second oscillator 101b is input. input. Since the received signal and the transmitted signal are input to a single A / D converter 104, the jitter generated when the transmitted signal is converted from the analog signal to the digital signal and when the received signal is converted from the analog signal to the digital signal. The jitter generated in is almost the same as or close to that of the signal.
  • the reference time of the transmission signal and the reference time of the received signal when measuring the propagation time of the acoustic signal can be matched, and the influence of jitter when measuring the propagation time of the acoustic signal can be reduced. .. That is, it is possible to accurately obtain the propagation time of the acoustic signal. Therefore, it can be applied to situations where high accuracy is required, such as measurement of a minute flow rate. Further, even if an inexpensive A / D converter is used, the influence of jitter when measuring the propagation time of the acoustic signal can be reduced, so that the cost of the device can be reduced.
  • FIG. 5 is a time chart of a control signal, a transmission signal, and a reception signal.
  • FIG. 5A shows the waveform of the control signal.
  • FIG. 5B shows the waveform of the transmission signal output from the amplifier 302.
  • the time T1 in FIG. 5B is the time difference between the rise start time of the control signal and the rise start time of the transmission signal output from the amplifier 302.
  • the time T1 is the delay time of the transmission signal output from the amplifier 302 (the time required for the amplifier 302 to amplify the transmission signal).
  • FIG. 5C shows the waveform of the transmission signal output from the attenuator 303 and the waveform of the reception signal output from the second oscillator 101b.
  • the time T2 in FIG. 5C is the time difference between the rising start time of the transmission signal output from the attenuator 303 and the rising start time of the received signal output from the second oscillator 101b.
  • FIG. 5D shows the waveform of the transmission signal output from the amplifier 301 and the waveform of the reception signal output from the amplifier 301.
  • the time T3 on the left side of FIG. 5D is the delay time of the transmission signal output from the amplifier 301 (the time required for the amplifier 301 to amplify the transmission signal).
  • the time T3 on the right side of FIG. 5D is the delay time of the received signal output from the amplifier 301 (the time required for the amplifier 301 to amplify the received signal).
  • FIG. 5D shows the waveform of the transmission signal output from the amplifier 301 and the waveform of the reception signal output from the amplifier 301.
  • the time T3 on the left side of FIG. 5D is the delay time of the transmission signal output from the amplifier 301 (the time required for the amplifier 301 to
  • FIG. 5 (E) shows the signal acquisition time by the A / D converter 104. After the control signal is input from the control circuit 102 to the A / D converter 104, the signal is taken in by the A / D converter 104 for a predetermined time.
  • FIG. 5F shows a waveform of a transmission signal input to the control circuit 102 and a waveform of a reception signal input to the control circuit 102.
  • the time T4 in FIG. 5F is the time difference between the rise start time (Tos) of the transmission signal input to the control circuit 102 and the rise start time (Tor) of the received signal input to the control circuit 102.
  • the signal processing unit 111 subtracts the rise start time (Tor) of the received signal input to the control circuit 102 from the rise start time (Tos) of the transmission signal input to the control circuit 102, so that the first oscillator 101a
  • the propagation time Tab of the acoustic signal from the second oscillator 101b to the second oscillator 101b is calculated.
  • T4 Tos-Tor- (T3-T3)).
  • T3 Tos-Tor- (T3-T3)
  • the delay times of the amplified transmitted signal and received signal vary.
  • the transmission signal and the reception signal are amplified by a single amplifier 301 and input to the A / D converter 104, the variation in the delay time of the amplified transmission signal and the reception signal is suppressed. can do. Therefore, it is possible to reduce the influence of variations in the delay times of the transmission signal and the reception signal when measuring the propagation time of the acoustic signal, and it is possible to accurately obtain the propagation time of the acoustic signal.
  • the above-described embodiment merely illustrates the configuration example of the present invention.
  • the present invention is not limited to the above-mentioned specific form, and various modifications can be made within the scope of its technical idea.
  • the propagation time measuring device 1 may simply perform a process of measuring the propagation time. In that case, the processes of steps S100 to S108 in the flow of FIG. 4 may be simply executed. Further, if the propagation time is simply measured, the propagation angle ⁇ may be 90 degrees.
  • the clamp-on type device that can be attached so as to sandwich the pipe is exemplified, but a pipe built-in type device configuration may be adopted.
  • the number of oscillators may be three or more, and the oscillator pair used for propagating the acoustic signal from the upstream side to the downstream side and the oscillator pair used for propagating the acoustic signal from the downstream side to the upstream side are separated. May be good.
  • the propagation time measuring device 1 of the above embodiment adopts a configuration having the amplifiers 301, 302 and the attenuator 303, but the installation of the amplifiers 301, 302 and the attenuator 303 is not essential. If the signal level of the transmission signal generated by the transmission signal generator 103 is sufficiently high, the installation of the amplifier 301 and the attenuator 303 may be omitted. If the signal level of the transmitted signal generated by the transmission signal generator 103 is sufficiently high and the signal level of the received signal output from the second oscillator 101b is sufficiently high, the amplifiers 301, 302 and the attenuator The installation of 303 may be omitted. Further, when the measurement range of the A / D converter 104 is large, the installation of at least one of the amplifiers 301, 302 and the attenuator 303 may be omitted.
  • the second vibration that receives the child (101a) and the acoustic signal transmitted from the first oscillator (101a) and propagated through the fluid (121) in the pipe (120) and converts it into a received signal as an electric signal.
  • Propagation time measuring device 101 Oscillator 101a: First oscillator 101b: Second oscillator 102: Control circuit 103: Transmission signal generator 104: A / D converter 111: Signal processing unit 120: Piping 121: Fluid 201a, 201b: Signal line 201c: Bypass line

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Volume Flow (AREA)
PCT/JP2021/032623 2020-09-15 2021-09-06 伝搬時間測定装置 WO2022059540A1 (ja)

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JP2000346686A (ja) * 1999-06-08 2000-12-15 Fuji Electric Co Ltd 超音波流量計
JP2016156665A (ja) * 2015-02-24 2016-09-01 横河電機株式会社 超音波流量計

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KR100861827B1 (ko) * 2003-11-10 2008-10-07 마츠시타 덴끼 산교 가부시키가이샤 초음파 유량계와 그 제조 방법
EP2101160B1 (en) * 2006-12-27 2015-04-08 Panasonic Corporation Ultrasonic flow meter
JP2008304281A (ja) * 2007-06-06 2008-12-18 Honda Electronic Co Ltd 超音波流量測定方法、超音波流量計、及び超音波流量測定プログラム
EP2522963A4 (en) * 2010-01-07 2013-09-25 Panasonic Corp ULTRASOUND FLOWMETER
JP2012021899A (ja) * 2010-07-15 2012-02-02 Panasonic Corp 超音波流量計測ユニットおよびこれを用いた超音波流量計

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JPS5658583U (zh) * 1979-10-12 1981-05-20
JP2000346686A (ja) * 1999-06-08 2000-12-15 Fuji Electric Co Ltd 超音波流量計
JP2016156665A (ja) * 2015-02-24 2016-09-01 横河電機株式会社 超音波流量計

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