WO2011055532A1

WO2011055532A1 - Ultrasonic flowmeter

Info

Publication number: WO2011055532A1
Application number: PCT/JP2010/006459
Authority: WO
Inventors: 裕史藤井; 尋一後藤; 葵渡辺
Original assignee: パナソニック株式会社
Priority date: 2009-11-06
Filing date: 2010-11-02
Publication date: 2011-05-12
Also published as: JP2011117956A

Abstract

Disclosed is an ultrasonic flowmeter which automatically corrects, without actually having a fluid flow, the difference between the actual size of measurement flow channel (1) and a flow channel size for calculating the flow volume, said flow channel size being set in control unit (4). The ultrasonic flowmeter is provided with, for example: a pair of ultrasonic vibrators (2, 7) which can transmit and receive ultrasonic signals; propagation time measuring unit (5), which measures the propagation time required for ultrasonic vibrator (7) to receive the ultrasonic signals transmitted from ultrasonic vibrator (2); control unit (4), which obtains a flow volume from the propagation time; received waveform amplitude measuring unit (9), which measures the amplitude of the waveform received by ultrasonic vibrator (7); and measuring flow channel size correcting unit (11), which corrects the size of the measurement flow channel on the basis of the difference between the amplitude and the amplitude of the specified received waveform. Thus, the difference between the actual size of measurement flow channel (1), and the size set for measuring flow channel (1) in the control unit (4) for calculating the flow volume can be corrected.

Description

Ultrasonic flow meter

The present invention relates to an ultrasonic flowmeter that measures the propagation time of ultrasonic waves using a pair of ultrasonic transducers capable of transmitting and receiving and measures the flow rate of a fluid to be measured.

The ultrasonic propagation time measurement method used in conventional ultrasonic flowmeters is a method in which a pair of ultrasonic transducers capable of transmitting and receiving are arranged facing each other and one ultrasonic transducer is driven by a burst signal. The ultrasonic wave was transmitted and received and measured by the other ultrasonic transducer.

Fig. 6 shows a transmission / reception waveform diagram of the ultrasonic flowmeter. In FIG. 6, the horizontal axis indicates time, and the vertical axis indicates voltage. Further, the upper side of FIG. 6 shows the driving waveform A of the transmitting-side ultrasonic transducer, and the lower side of FIG. 6 shows the received waveform B received by the receiving-side ultrasonic transducer. In the figure, T0 indicates the start point of the drive waveform A, and T1 indicates the end point of the third wave after the start of drive. R0 indicates the reception start time, and R1 indicates the end time of the third wave after the start of reception. For example, in the fluid flow measuring device (ultrasonic flowmeter) disclosed in Patent Document 1, the m-th wave of driving waveform A (m is an integer, in the ultrasonic transducer on the transmission side, an example shown in FIG. Then, the zero crossing point T1 of m = 3) is set as the starting point of propagation time measurement, and the mth (m = 3) wave of the received waveform B received by the other ultrasonic transducer is set as the end point R1. Then, the flow measuring device measures the time Tp between the starting point T1 and the end point R1 as the propagation time of the ultrasonic wave, measures the flow velocity of the fluid to be measured using the propagation time, and calculates the flow rate. It was.

FIG. 7 shows the configuration of the fluid flow measuring device disclosed in Patent Document 1. This flow measurement apparatus includes an ultrasonic transducer 2 installed in a measurement flow path 1 through which a fluid flows, a drive circuit 3 that drives the ultrasonic transducer 2, a control unit 26 that outputs a start signal to the drive circuit 3, A propagation time measuring unit 5 that measures the propagation time of the ultrasonic wave, an ultrasonic vibrator 7 that receives the ultrasonic wave transmitted from the ultrasonic vibrator 2, an amplifier 6 that amplifies the output of the ultrasonic vibrator 7, and an amplifier 6 And a reception detection circuit 8 that stops the propagation time measurement unit 5 when the magnitude relationship is inverted by comparing the output of the signal and the reference voltage.

In addition, in this flow measuring device, the inverse propagation time difference method is used so that the influence of the temperature on the sound speed can be ignored. For this purpose, the changeover switch 10 is generally provided. The changeover switch 10 is used to measure the propagation time of the ultrasonic wave from the upstream side to the downstream side of the measurement flow channel 1 and the propagation time from the downstream side to the upstream side.

Further, in this flow measuring apparatus, in order to determine the zero cross point at the end of the m-th (m = 3) wave, the reference voltage 25 is set in advance between the amplitudes of the second and third waves. The next zero cross when the received signal exceeds the reference voltage 25 is set to be the third wave. The flow measuring device includes a received waveform amplitude measuring unit 9 for automatically adjusting the reference voltage 25 when the flow measuring device is initially set. In the reception waveform amplitude measuring unit 9, by increasing the reference voltage 25 for detecting reception little by little from a low voltage, a voltage whose propagation time changes can be stored as each amplitude of the reception wave.

For example, as shown in FIG. 6, even if the reference voltage 25 is changed from V1 to V2, the propagation time remains Ta because the reference voltage 25 is within the amplitude range of the first wave. On the other hand, if the reference voltage 25 is changed from V1 to V3, the reference voltage 25 is in a range larger than the amplitude (V2) of the first wave and smaller than the amplitude (V3) of the second wave. Therefore, the propagation time is Tb. Therefore, it can be seen that the voltage at which the propagation time is switched from Ta to Tb, in this example, V2, is the amplitude of the first wave of the received wave. In this way, the amplitude (voltage) of each wave from the first wave of the received wave to the peak wave (the wave having the maximum amplitude among the waves constituting the series of received waveforms B) by switching the propagation time. Can be measured. The amplitude of the second and third waves is selected from the measured amplitudes up to the peak wave, and is normally measured between the voltage that is the amplitude of the second wave and the voltage that is the amplitude of the third wave. The hourly reference voltage 25 can be set.

JP 2006-308449 A

However, in the conventional technique, if there is a difference between the actual dimension of the measurement channel and the channel size for flow rate calculation set in the control unit 4, an error occurs in the measurement result. Therefore, there has been a problem that it is necessary to correct a measured value by actually flowing a predetermined flow rate at the manufacturing stage of the ultrasonic flowmeter.

The present invention has been made to solve such a problem. In the manufacturing stage, it is not necessary to flow the measured fluid at an actual flow rate to correct the difference in the dimensions of the measurement flow path. An object of the present invention is to provide an ultrasonic flowmeter that can be manufactured at a lower cost.

In order to solve the above-described problem, an ultrasonic flowmeter according to the present invention includes a measurement channel for flowing a fluid to be measured for measuring a flow rate, and a pair of ultrasonic channels arranged in the measurement channel and capable of transmitting and receiving ultrasonic signals. An ultrasonic transducer, and a propagation time measuring unit that measures a propagation time until the other ultrasonic transducer receives an ultrasonic signal transmitted from one ultrasonic transducer and propagated through the fluid to be measured, A control unit that calculates the flow rate of the fluid to be measured that satisfies the space between the ultrasonic transducers from the propagation time, and a received waveform amplitude measuring unit that measures the amplitude of the mth wave of the received waveform received by the ultrasonic transducer And the difference between the amplitude of each measured waveform of the received waveform and the amplitude of the m-th wave of the normal received waveform, the dimensional difference between the actual measurement channel and the measurement channel preset for flow rate calculation is estimated. Based on the estimation result, the control unit A measurement channel dimension correction unit for correcting the size of the measurement flow path is configured for flow calculation is Configurations which comprises a.

Further, in the ultrasonic flowmeter according to the present invention, the measurement flow path dimension correction unit is configured to determine an actual measurement flow path from a difference between the amplitude of each wave of the measured reception waveform and the amplitude of each wave of the normal reception waveform. And a dimensional difference between the measurement channel set in advance for flow rate calculation may be used.

Furthermore, the ultrasonic flowmeter according to the present invention provides a predetermined temperature between the measurement flow path, the ultrasonic transducer, the propagation time measurement unit, the control unit, and the pair of ultrasonic transducers. It is filled with the set fluid to be measured, and the ultrasonic propagation time between the ultrasonic transducers is measured and compared with the normal propagation time set in advance in the control unit. Estimate the difference between the distance between the actual ultrasonic transducers and the distance between the ultrasonic transducers set for flow rate calculation from the difference in propagation time, and set the flow rate calculation in the control unit based on the estimation result And an ultrasonic transducer distance correcting unit that corrects the distance between the ultrasonic transducers that are arranged.

The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings.

As described above, in the present invention, in the manufacturing stage, it is not necessary to flow the measured fluid at the actual flow rate to correct the difference in the dimensions of the measurement flow path, and the manufacturing can be performed at a lower cost than in the past. There is an effect that a possible ultrasonic flowmeter can be provided.

It is a block diagram which shows schematic structure of the ultrasonic flowmeter which concerns on Embodiment 1 of this invention. (A) is a schematic diagram which shows the propagation path of the ultrasonic wave in the said measurement flow path in case the height dimension of a measurement flow path is a reference value, (b) is the propagation path shown to (a). It is a wave form diagram which shows the received waveform of an ultrasonic wave. (A) is a schematic diagram which shows the propagation path of the ultrasonic wave in the said measurement flow path in case the height dimension of a measurement flow path is higher than a reference value, (b) is shown to (a). It is a wave form diagram which shows the received waveform of the ultrasonic wave in a propagation path. It is a block diagram which shows schematic structure of the ultrasonic flowmeter which concerns on Embodiment 2 of this invention. It is a block diagram which shows schematic structure of the ultrasonic flowmeter which concerns on Embodiment 3 of this invention. It is a wave form diagram which shows an example of the typical transmission wave and reception wave in a general ultrasonic flowmeter. It is a block diagram which shows schematic structure of the fluid flow measuring apparatus which is the conventional ultrasonic flowmeter.

DESCRIPTION OF SYMBOLS 1

Measurement flow path

2, 7 Ultrasonic vibrator 3

Drive circuit

4, 23, 24 Control part 5 Propagation time measurement part 8 Reception detection circuit 9 Received waveform amplitude measurement part 10 Changeover switch 11 Measurement flow path dimension correction | amendment part 22 Ultrasonic vibration Inter-child distance correction unit

First, the present invention will be described. The present invention includes a measurement flow channel for flowing a fluid to be measured for measuring a flow rate, a pair of ultrasonic transducers arranged in the measurement flow channel and capable of transmitting and receiving ultrasonic signals, A propagation time measuring unit for measuring a propagation time transmitted from one of the ultrasonic transducers until the other ultrasonic transducer receives an ultrasonic signal propagated through the fluid to be measured; A control unit for obtaining a flow rate of the fluid to be measured that fills between the ultrasonic transducers, a received waveform amplitude measuring unit that measures the amplitude of the mth wave of the received waveform received by the ultrasonic transducer, and the measured received waveform Based on the difference between the amplitude of each wave and the amplitude of the m-th wave of the regular received waveform, the dimensional difference between the actual measurement channel and the measurement channel preset for flow rate calculation is estimated. For the flow rate calculation in the control unit Is an ultrasonic flowmeter structure comprises a measuring channel dimension correction unit for correcting the size of the measurement flow path is constant, a.

According to the above configuration, the measurement flow channel set as the actual measurement flow channel can be obtained without flowing the measured fluid at the actual flow rate and checking the measurement value error at the manufacturing stage of the ultrasonic flow meter. And the difference in dimensions can be corrected. Therefore, the deviation of the flow rate value due to the dimensional deviation of the measurement flow path can be suitably corrected. Therefore, an expensive flow rate generator is not required in the manufacturing process, and the time required for dimensional correction can be shortened. Therefore, it is possible to manufacture an ultrasonic flowmeter at a lower cost than in the past.

In the ultrasonic flowmeter having the above-described configuration, the m-th wave measured by the received waveform amplitude measuring unit may be a peak wave. By setting the m-th wave as a peak wave, the accuracy of dimensional correction can be improved.

The present invention also provides a measurement channel for flowing a fluid to be measured for measuring a flow rate, a pair of ultrasonic transducers arranged in the measurement channel and capable of transmitting and receiving ultrasonic signals, and one of the ultrasonic vibrations A propagation time measuring unit that measures a propagation time until the other ultrasonic transducer receives an ultrasonic signal transmitted from the child and propagated through the fluid to be measured, and between the ultrasonic transducers by calculation from the propagation time. A control unit for obtaining a flow rate of the fluid to be measured to be satisfied, a received waveform amplitude measuring unit for measuring the amplitudes of a plurality of received waveforms received by the ultrasonic transducer, and the amplitude and normality of each wave of the measured received waveform Estimate the dimensional difference between the actual measurement flow path and the measurement flow path set in advance for flow rate calculation from the difference between the amplitude of each wave of the received waveform, and based on this estimation result, calculate the flow rate in the control unit. Set the measurement channel dimensions A measurement channel dimension correction unit positive for, may be an ultrasonic flowmeter structure comprises a.

Even with the above-described configuration, it is possible to correct the dimensional difference of the measurement flow path without flowing the measured fluid at the actual flow rate and checking the measurement value error at the manufacturing stage. Therefore, it is possible to manufacture an ultrasonic flowmeter at a lower cost than in the past.

In the ultrasonic flowmeter having the above-described configuration, the present invention may be configured such that at least one of the plurality of waves measured by the received waveform amplitude measuring unit is a peak wave. By including peak waves in the plurality of waves to be measured, the accuracy of dimensional correction can be improved.

The present invention also provides a measurement channel for flowing a fluid to be measured for measuring a flow rate, a pair of ultrasonic transducers arranged in the measurement channel and capable of transmitting and receiving ultrasonic signals, and one of the ultrasonic vibrations A propagation time measuring unit that measures a propagation time until the other ultrasonic transducer receives an ultrasonic signal transmitted from the child and propagated through the fluid to be measured, and between the ultrasonic transducers by calculation from the propagation time. A control unit for obtaining the flow rate of the fluid to be measured to be filled, and a predetermined fluid to be measured with a predetermined temperature set between the pair of ultrasonic transducers, and the propagation time of the ultrasonic wave between the ultrasonic transducers is measured. Compared with the normal propagation time previously set in the control unit, the ultrasonic wave set for calculating the distance between the actual ultrasonic transducers and the flow rate from the difference between the measured propagation time and the normal propagation time. Estimate the distance difference between the transducers and The ultrasonic flowmeter may be configured to include an ultrasonic transducer distance correction unit that corrects a distance between ultrasonic transducers set for flow rate calculation in the control unit based on the result. .

According to the above configuration, since the difference in distance between the ultrasonic transducers can be automatically corrected, more accurate dimensional correction can be performed without causing the fluid to be measured to flow at an actual flow rate.

In the ultrasonic flowmeter having the above-described configuration, the ultrasonic wave propagation between ultrasonic transducers may be achieved by filling the predetermined fluid to be measured with a predetermined temperature between the pair of ultrasonic transducers. The time is measured, compared with the normal propagation time set in advance in the control unit, and the distance between the actual ultrasonic transducers and the flow rate calculation are set based on the difference between the measured propagation time and the normal propagation time. A distance correction unit between the ultrasonic transducers that estimates a difference in distance between the ultrasonic transducers and corrects a distance between the ultrasonic transducers set for flow rate calculation in the control unit based on the estimation result. The structure provided may be sufficient.

According to the above configuration, not only the measurement flow path but also the difference in distance between the ultrasonic transducers can be automatically corrected, so that more accurate dimensional correction can be made without flowing the measured fluid at the actual flow rate. And distance correction becomes possible.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and redundant description thereof is omitted.

(Embodiment 1)
FIG. 1 is a block diagram showing an example of the configuration of the ultrasonic flowmeter according to Embodiment 1 of the present invention.

As shown in FIG. 1, the ultrasonic flowmeter according to the present embodiment includes a pair of

ultrasonic transducers

2 and 7, a drive circuit 3, a control unit 4, a propagation time measuring unit 5, an amplifier 6, A reception detection circuit 8, a changeover switch 10, a reception waveform amplitude measurement unit 9, and a measurement flow path dimension correction unit 11 are provided.

The

ultrasonic vibrators

2 and 7 are installed in the measurement channel 1 through which the fluid to be measured flows, and the

ultrasonic vibrators

2 and 7 are driven by the drive circuit 3. Transmission / reception between the upstream ultrasonic transducer 7 and the downstream ultrasonic transducer 2 is switched by a changeover switch 10. The amplifier 6 amplifies the outputs (particularly ultrasonic reception waves) of the

ultrasonic transducers

2 and 7 and outputs them to the reception detection circuit 8. The reception detection circuit 8 compares the output of the amplifier 6 with the reference voltage, and stops the propagation time measurement unit 5 when the magnitude relationship is reversed.

The control unit 4 controls the ultrasonic flowmeter shown in FIG. Specifically, a start signal can be output to the drive circuit 3 and, as will be described later, an ultrasonic signal transmitted and received between the

ultrasonic transducers

2 and 7 by controlling the propagation time measurement unit 5. Calculation of the flow rate of the fluid to be measured that fills the space between the

ultrasonic transducers

2 and 7 from the propagation time, and control of the changeover switch 10, the received waveform amplitude measuring unit 9 and the measurement channel size correcting unit 11. The set value is corrected from the output of.

As described above, the propagation time measuring unit 5 measures the propagation time of the ultrasonic wave between the

ultrasonic transducers

2 and 7 used for the calculation under the control of the control unit 4, and also converts the received waveform of the ultrasonic wave into the received waveform amplitude. Output to the measurement unit 9. The received waveform amplitude measuring unit 9 measures the amplitude from the first wave to the peak wave of the received waveform of the ultrasonic wave, and outputs it to the control unit 4 and the measurement flow path dimension correcting unit 11. The measurement flow path dimension correction unit 11 corrects the measurement flow path dimension from the difference between the amplitude of each wave of the received waveform and the amplitude of the reference reception waveform set in advance (details of the correction process will be described later).

The control switch 4 sets the ultrasonic transducer 2 to the reception side and the ultrasonic transducer 7 to the transmission side under the control of the control unit 4. In this state, the ultrasonic vibrator 2 is driven by the drive circuit 3 and the ultrasonic wave propagated through the fluid to be measured is received by the ultrasonic vibrator 2. The received ultrasonic wave (received wave) is input to the propagation time measurement unit 5 via the amplifier 6 and the reception detection circuit 8, and the propagation time of the ultrasonic wave is measured. When the control unit 4 performs an operation for obtaining the flow rate of the fluid to be measured, the control unit 4 acquires the propagation time indirectly from the propagation time measurement unit 5, or the propagation time through a signal transmission path (not shown). The propagation time may be acquired directly from the measurement unit 5.

As the ultrasonic transducer 2, the ultrasonic transducer 7, the drive circuit 3, the amplifier 6, the reception detection circuit 8, and the changeover switch 10, those known in the field of ultrasonic flowmeters are preferably used.

In the present embodiment, the control unit 4 is configured by, for example, a microcomputer, and the microcomputer is configured by, for example, a calculation unit and a storage unit, although not illustrated in FIG. The arithmetic unit is composed of a CPU of a microcomputer, and the storage unit is composed of an internal memory. Various programs are stored in the storage unit, and various set values such as the dimensions of the measurement flow path set in advance for flow rate calculation are stored. The calculation unit executes the above-described calculation for determining the flow rate using the program stored in the storage unit, and corrects the setting value stored in the storage unit as necessary. The storage unit is not limited to the internal memory, and may be configured as an independent memory or may be configured from a plurality of storage devices.

Further, the propagation time measurement unit 5, the received waveform amplitude measurement unit 9, and the measurement flow path dimension correction unit 11 may be configured as a logic circuit or the like using a known switching element, subtractor, comparator, or the like. May be a configuration realized by operating according to a program stored in the storage unit, that is, a functional configuration of the control unit 4.

The operation and action of the ultrasonic flowmeter configured as described above will be described below. First, a basic flow measurement operation and the like will be described with reference to FIG. 6. The ultrasonic flowmeter according to the present embodiment is the m-th drive waveform (m is an integer, and is shown in FIG. 6. In the example, in order to determine the zero crossing point at the end of m = 3), the reference voltage 25 is set in advance between the amplitudes of the second and third waves, and the received signal (received wave) exceeds the reference voltage 25. The next zero cross is set to be the zero cross at the end of the third wave. The reference voltage 25 is a voltage for detecting reception of a received wave, and the reception waveform amplitude measuring unit 9 adjusts the reference voltage 25 slightly from a low voltage in order to automatically adjust the reference voltage 25 at the initial setting. By increasing the voltage one by one, the voltage whose propagation time changes is stored as the amplitude of each received wave.

In the drive waveform A of the ultrasonic transducer 2 on the transmission side, as described above, the starting point of the propagation time measurement is set to the zero-cross point T1 of the m-th (m = 3) wave. Therefore, if the zero cross of the m-th (m = 3) wave of the received waveform B received by the receiving-side ultrasonic transducer 7 is set as the end point R1, the propagation time measuring unit 5 determines the start point T1 and the end point R1. Can be measured as the propagation time of the ultrasonic wave. Then, the control unit 4 measures the flow velocity of the fluid under measurement using the propagation time, and calculates the flow rate of the fluid under measurement.

Furthermore, in the present embodiment, the measurement channel size correction unit 11 is configured to control the actual height of the measurement channel 1 (the channel diameter of the measurement channel 1) and the flow rate value in advance. 4 is corrected based on the difference from the reference height dimension stored in the storage section 4 that constitutes 4. As a means for correcting, ultrasonic waves are transmitted and received in the state where no flow rate is generated in the measurement flow channel 1 during the manufacture of the ultrasonic flowmeter, and the first to nth waves (n is the peak wave) of the received waveform. The received waveform amplitude measuring unit 9 measures the amplitude of each wave up to an arbitrary integer).

Here, assuming that the phenomenon when the height dimension of the measurement channel 1 is deviated from the reference dimension is n = 2, refer to FIGS. 2 (a), 2 (b) and FIGS. 3 (a), 3 (b). To explain. FIG. 2A shows an ultrasonic wave propagation path when the dimension of the measurement channel 1 is the same as that of the reference, and FIG. 2B shows an ultrasonic wave reception waveform in this propagation path. FIG. 3A shows an ultrasonic wave propagation path when the height dimension of the measurement channel 1 is higher than the reference, and FIG. 3B shows an ultrasonic reception waveform in the propagation path. .

As shown in FIG. 2A, when the height dimension H of the measurement flow channel 1 is the same as the reference, the received waveform of the ultrasonic wave passes through the path 12 that goes straight between the

ultrasonic transducers

2 and 7. The waveform of the ultrasonic wave and the waveform of the ultrasonic wave that has passed through the path 13 reflected by the inner surface of the measurement channel 1 are combined. Therefore, the received wave received by the ultrasonic transducer 2 is, as shown in FIG. 2B, the received waveform 15 of the ultrasonic wave passing through the path 12 and the received waveform of the ultrasonic wave passing through the path 13. 16, the amplitude 18 a and the amplitude 18 b of each wave (first wave and second wave) are both larger than the amplitude of the reception waveform 15 or the reception waveform 16.

On the other hand, as shown in FIG. 3A, when the height dimension H ′ of the measurement channel 1 is higher than the height dimension H of the reference measurement channel 1, The path 14 that is reflected by hitting the inner surface of the path 1 is longer than the example shown in FIG. 2A, and the time until the ultrasonic wave arrives at the ultrasonic transducer 2 on the receiving side is delayed. Therefore, the received wave received by the ultrasonic transducer 2 is a combined waveform 20 of the received waveform 15 and the received waveform 19 as shown in FIG.

Here, if the synthetic waveform 17 shown in FIG. 2B is a normal waveform (reference waveform), the measurement flow channel 1 can be obtained by comparing the synthetic waveform 20 with the normal waveform (synthetic waveform 17). The difference between the height dimension H and the dimension H ′ can be estimated. That is, as shown in FIG. 3B, the amplitude 21a and the amplitude 21b of each wave (the first wave and the second wave) in the synthesized waveform 20 are the amplitude 18a and the amplitude of the synthesized waveform 17 which is a normal waveform. Since it is smaller than 18b, the actually measured amplitude 21a and amplitude 21b will deviate from the reference amplitude 18a and amplitude 18b. This deviation corresponds to the difference between the height dimensions H and H ′ (dimension deviation).

In the control unit 4, based on the above principle, the relationship between the amplitude of the combined wave formed when an amplitude shift occurs in each wave of the received waveform and the height dimension of the measurement channel 1, The correction amount is set and stored in advance in the storage unit. Then, the measurement channel dimension correction unit 11 calculates the measurement channel 1 by a preset correction amount based on the difference between the measured amplitude of each wave and the amplitude set and stored in the storage unit in advance. Correct the height dimension above. Thereby, the deviation of the measured value caused by the actual deviation of the dimension of the measurement channel 1 can be corrected. Note that the correction amount may not be stored in the storage unit in advance, but may be calculated and acquired by the calculation unit.

As described above, in the present embodiment, the measurement flow path dimension correction unit 11 is provided so that the measured fluid does not flow through the measurement flow path 1 at the actual flow rate when the ultrasonic flowmeter is manufactured. The deviation of the flow rate value due to the dimensional deviation of the measurement channel 1 can be suitably corrected.

Here, the correction amount set in the storage unit is based on the measurement result using the predetermined fluid to be measured, and the measurement for performing the correction is also performed using the same predetermined fluid to be measured. .

In this embodiment, the number of waves whose amplitude is to be measured is described as 2 (first wave and second wave). However, an arbitrary number of waves from the first wave to the peak wave are measured and compared. It is also possible to do. In particular, if a peak wave is included in a wave whose amplitude is to be measured, the peak wave has the largest amplitude in the received waveform. Therefore, if the dimension of the measurement channel 1 is shifted, the difference from the amplitude in the reference case is relative. Become bigger. Therefore, the accuracy of dimensional correction (as well as the accuracy of deviation in flow rate value) can be improved.

Furthermore, if the amplitude is measured for all the waves from the first wave to the peak wave and compared with the amplitude in the case of the reference, the accuracy of dimensional correction can be further improved.

Further, in the present embodiment, the number of waves whose amplitude is measured need not be plural. For example, the amplitude may be compared for one wave of the m-th wave (any wave from the first wave to the n-th wave). In this case, if the m-th wave is a peak wave, that is, m = n, the accuracy of dimensional correction can be further improved.

Further, as described above, the reference configuration (particularly, the position where the

ultrasonic transducers

2 and 7 are disposed with respect to the measurement flow path 1) employed when determining the correction amount stored in the storage unit is a correction target. It is preferable that the measurement channel 1 is also shared. In other words, it is preferable that the reference configuration is always set to have a predetermined positional relationship. For example, the point where the

ultrasonic transducers

2 and 7 are arranged at the center of the cross section of the measurement flow channel 1 is set so as to have a common configuration. Thereby, the correction accuracy can be further improved.

(Embodiment 2)
Next, an ultrasonic flowmeter according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a block diagram illustrating an example of the configuration of the ultrasonic flowmeter according to the second embodiment. As shown in FIG. 4, the ultrasonic flowmeter according to the present embodiment has the same basic structure as that of the ultrasonic flowmeter according to the first embodiment, but the measurement flow path dimensions. The difference is that the correction unit 11 is not provided and the ultrasonic transducer distance correction unit 22 is provided.

The control unit 23 includes, for example, a calculation unit and a storage unit, similarly to the control unit 4 in the first embodiment. In the storage unit, in addition to the above-described program, a propagation time (set value) measured using a predetermined fluid to be measured set to a predetermined temperature is set in advance, and the

ultrasonic transducers

2 and 7 For the inter-vibrator distance, which is the distance between them, a calculated value (a set value used when calculating the flow rate) is preset. Of course, other set values may be stored.

The ultrasonic transducer distance correction unit 22 may be configured as a logic circuit or the like using a known switching element, subtractor, comparator, or the like, or realized by the arithmetic unit operating according to a program stored in the storage unit. That is, the functional configuration of the control unit 23 may be used.

Since the basic operation of the ultrasonic flowmeter according to the present embodiment is the same as that of the ultrasonic flowmeter according to the first embodiment, the description thereof will be omitted, and the operation of the ultrasonic transducer distance correction unit 22 will be omitted. explain.

The ultrasonic transducer distance correction unit 22 measures the propagation time (measured value) in a state where the measurement flow path 1 is filled with a predetermined fluid to be measured set to a predetermined temperature when the ultrasonic flowmeter is manufactured. Thereafter, based on the difference between the preset propagation time setting value and the propagation time measurement value, the difference between the preset inter-vibrator distance setting value and the actual inter-vibrator distance is obtained. Then, the inter-vibrator distance stored in the storage unit is corrected from the obtained difference. Thereby, the deviation of the measured value can be corrected.

(Embodiment 3)
Next, an ultrasonic flowmeter according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 5 is a block diagram illustrating an example of the configuration of the ultrasonic flowmeter according to the third embodiment. As shown in FIG. 5, the ultrasonic flowmeter according to the present embodiment has the same basic structure as that of the ultrasonic flowmeter according to the second embodiment. The difference is that a dimension correction unit 11 is provided.

The control unit 24 includes, for example, a calculation unit and a storage unit, similar to the control unit 4 in the first embodiment, and the above-described various setting values are set in the storage unit.

Since the basic operation of the ultrasonic flowmeter according to the present embodiment is the same as that of the ultrasonic flowmeter according to the first or second embodiment, it is omitted, and the measurement flow path dimension correction unit 11 and the ultrasonic wave are omitted. The operation of the inter-vibrator distance correction unit 22 will be described.

The measurement channel size correction unit 11 stores in advance a measurement value of the amplitude of each wave included in the received wave and a storage unit in a state where the measurement channel 1 is filled with a predetermined fluid to be measured set to a predetermined temperature. Based on the difference from the set amplitude value, the calculated height dimension of the measurement channel 1 is corrected by a preset correction amount, and then the ultrasonic transducer distance correcting unit 22 is corrected. Thus, the deviation of the inter-vibrator distance is corrected.

That is, the measurement channel dimension correction unit 11 corrects the dimension of the measurement channel 1 based on the difference between the measured value and the set value of the amplitude. However, the measurement of the amplitude is almost affected by the deviation of the distance between the transducers. Absent. Then, the ultrasonic transducer distance correction unit 22 corrects the deviation of the inter-vibrator distance by measuring the propagation distance based on the dimension correction of the measurement channel 1. Therefore, the object (amplitude) measured by the measurement flow path dimension correction unit 11 and the object (propagation distance) measured by the ultrasonic transducer distance correction unit 22 are substantially independent measurement objects. As a result of the dimensional correction by the measurement flow path dimension correction unit 11, the correction accuracy of the deviation between the transducer distances in the ultrasonic transducer distance correction unit 22 can be further improved.

As described above, in the present embodiment, by providing the measurement flow channel dimension correction unit 11 and the ultrasonic transducer distance correction unit 22, the fluid to be measured is placed in the measurement flow channel 1 when the ultrasonic flowmeter is manufactured. Even if the actual flow rate does not flow, it is possible to suitably correct the deviation of the flow rate value due to the deviation of the dimension of the measurement channel 1 and the distance between the ultrasonic transducers 2 and 7 (distance between the transducers). it can.

From the above description, many modifications and other embodiments of the present invention are apparent to persons skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

As described above, the ultrasonic flowmeter according to the present invention does not require an actual flow rate in the manufacturing stage to correct the difference in the dimensions of the measurement flow path, so that an expensive flow rate generator is not required in the manufacturing process. The time required for correction can be shortened. Therefore, it is possible to manufacture ultrasonic flowmeters at a lower cost than conventional methods, so it is widely used in applications that measure the flow rate of fluids with ultrasonic waves, such as flow measurement standards, gas meters, or water meters. Can be applied.

Claims

A measurement flow path for flowing a fluid to be measured for measuring a flow rate;
A pair of ultrasonic transducers arranged in the measurement channel and capable of transmitting and receiving ultrasonic signals;
A propagation time measuring unit that measures a propagation time transmitted from one ultrasonic transducer until the other ultrasonic transducer receives an ultrasonic signal propagated through the fluid to be measured;
A control unit for obtaining a flow rate of a fluid to be measured that fills between the ultrasonic transducers by calculation from the propagation time;
A received waveform amplitude measuring unit that measures the amplitude of the mth wave of the received waveform received by the ultrasonic transducer;
From the difference between the amplitude of each measured waveform of the received waveform and the amplitude of the m-th wave of the regular received waveform, the dimensional difference between the actual measurement channel and the measurement channel preset for flow rate calculation is estimated, An ultrasonic flowmeter comprising: a measurement channel size correction unit that corrects a measurement channel size set for flow rate calculation in the control unit based on the estimation result.
The ultrasonic flowmeter according to claim 1, wherein the m-th wave measured by the received waveform amplitude measuring unit is a peak wave.
A measurement flow path for flowing a fluid to be measured for measuring a flow rate;
A pair of ultrasonic transducers arranged in the measurement channel and capable of transmitting and receiving ultrasonic signals;
A propagation time measuring unit that measures a propagation time transmitted from one ultrasonic transducer until the other ultrasonic transducer receives an ultrasonic signal propagated through the fluid to be measured;
A control unit for obtaining a flow rate of a fluid to be measured that fills between the ultrasonic transducers by calculation from the propagation time;
A received waveform amplitude measuring unit that measures the amplitude of a plurality of received waveforms received by the ultrasonic transducer;
Estimate the dimensional difference between the actual measurement channel and the measurement channel preset for flow rate calculation from the difference between the amplitude of each wave of the measured received waveform and the amplitude of each wave of the regular received waveform. An ultrasonic flowmeter, comprising: a measurement channel dimension correcting unit that corrects a dimension of a measurement channel set for flow rate calculation in the control unit based on a result.
The ultrasonic flowmeter according to claim 3, wherein at least one of the plurality of waves measured by the received waveform amplitude measuring unit is a peak wave.
A measurement flow path for flowing a fluid to be measured for measuring a flow rate;
A pair of ultrasonic transducers arranged in the measurement channel and capable of transmitting and receiving ultrasonic signals;
A propagation time measuring unit that measures a propagation time transmitted from one ultrasonic transducer until the other ultrasonic transducer receives an ultrasonic signal propagated through the fluid to be measured;
A control unit for obtaining a flow rate of a fluid to be measured that fills between the ultrasonic transducers by calculation from the propagation time;
The pair of ultrasonic transducers is filled with a predetermined fluid to be measured which is set to a predetermined temperature, and the propagation time of ultrasonic waves between the ultrasonic transducers is measured. Compared with the propagation time, from the difference between the measured propagation time and the regular propagation time, estimate the difference between the distance between the actual ultrasonic transducers and the distance between the ultrasonic transducers set for flow rate calculation, An ultrasonic flowmeter comprising: an ultrasonic transducer distance correction unit that corrects a distance between ultrasonic transducers set for flow rate calculation in the control unit based on an estimation result.
The pair of ultrasonic transducers is filled with a predetermined fluid to be measured which is set to a predetermined temperature, and the propagation time of ultrasonic waves between the ultrasonic transducers is measured. Compared with the propagation time, from the difference between the measured propagation time and the regular propagation time, estimate the difference between the distance between the actual ultrasonic transducers and the distance between the ultrasonic transducers set for flow rate calculation, 5. The ultrasonic transducer distance correcting unit that corrects the distance between ultrasonic transducers set for flow rate calculation in the control unit based on the estimation result, according to claim 3 or 4, The described ultrasonic flowmeter.