JP7184596B2 - Ultrasonic Flowmeter and Acquisition Method of Peak Height Information in Ultrasonic Flowmeter - Google Patents

Description

The present invention relates to an ultrasonic flowmeter that measures the flow rate of a fluid using ultrasonic waves and a peak height information acquisition method for the ultrasonic flowmeter.

2. Description of the Related Art Conventionally, an ultrasonic flowmeter that measures the flow rate of a fluid using ultrasonic waves has been used as a flowmeter that measures the flow rate of the fluid.

In this ultrasonic flowmeter, as shown in the schematic diagram of FIG. 12, a first ultrasonic transmitter/receiver (upstream transducer) 2 is arranged on the outer peripheral surface of the upstream side of the pipe 1 through which the fluid to be measured flows, A second ultrasonic transmitter/receiver (downstream transducer) 3 is arranged on the outer circumferential surface on the downstream side, and ultrasonic waves are transmitted between the first ultrasonic transmitter/receiver 2 and the second ultrasonic transmitter/receiver 3 via fluid. A measurement process for transmitting and receiving signals in both directions is performed multiple times, and the flow velocity v of the fluid is measured based on the propagation time difference of the ultrasonic signals in both directions obtained for each measurement process. The flow rate Q of the fluid is obtained from the cross-sectional area S (see Patent Document 1, for example).

In FIG. 12, θ is the angle between the axis of the pipe 1 and the propagation direction of the ultrasonic signal. Ultrasonic signals emitted from the first ultrasonic transmitter/receiver 2 and received by the second ultrasonic transmitter/receiver 3 (ultrasonic signals propagating from the upstream side to the downstream side (forward propagating ultrasonic signals) ) is represented by the following equation (1).
t1=L/(c+vcos θ) (1)
Here, L is the propagation distance [m] of the ultrasonic signal, and c is the speed of sound in the fluid [m/s]. Since ultrasonic waves propagate along with the flow of fluid, the faster the flow, the shorter the propagation time.

Similarly, ultrasonic signals emitted from the second ultrasonic transmitter/receiver 3 and received by the first ultrasonic transmitter/receiver 2 (ultrasonic signals propagating from the downstream side to the upstream side (ultrasonic signals propagating in the opposite direction) The propagation time t2 (reverse propagation time) of the sound wave signal)) is represented by the following equation (2).
t2=L/(c-vcosθ) (2)
Ultrasonic waves propagate against the flow of fluid, so the faster the flow, the longer it takes to propagate.

From the above formulas (1) and (2),
Δt=t2−t1=L/(c−vcos θ)−L/(c+vcos θ)=2 vL cos θ/(c ² −v ² cos ² θ)≈2 vL cos θ/c ² (3)
therefore,
v≈(c ² /2Lcos θ)·(t2−t1)=(c ² /2Lcos θ)·Δt (4)
becomes.
The flow rate Q of the fluid can be obtained from the flow velocity v and the cross-sectional area S of the pipe 1 .

FIG. 13(a) shows a waveform diagram (schematic diagram) of the reception signal (forward reception signal) output from the second ultrasonic transmitter/receiver 3, and FIG. 26(b) shows the first ultrasonic wave. FIG. 2 shows a waveform diagram (schematic diagram) of a reception signal (reverse reception signal) output from the transmitter/receiver 2. FIG.

In FIG. 12, the first ultrasonic transmitter/receiver 2 and the second ultrasonic transmitter/receiver 3 are alternately pulse-driven for a certain period of time. As a result, the pulsed ultrasonic signal (forward transmission signal) emitted from the first ultrasonic transmitter/receiver 2 is received by the second ultrasonic transmitter/receiver 3 via the fluid, and the second ultrasonic wave A pulsed ultrasonic signal (reverse transmission signal) emitted from the transmitter/receiver 3 is received by the first ultrasonic transmitter/receiver 2 via the fluid.

14(a) shows transmission signals output from the ultrasonic transmitter/receivers 2 and 3, and FIG. 14(b) shows reception signals output from the ultrasonic transmitter/receivers 2 and 3. FIG. In addition, in Fig.14 (a), the horizontal axis is reduced and shown. Also, in FIG. 14(a), tu indicates the period of the transmission signal.

After the pulse-like ultrasonic signal is emitted, the received signal is still small at the reception timing tr of the first pulse-like ultrasonic signal. Therefore, after a short time from the reception timing tr, when the received signal becomes large to some extent, the timing of the next zero crossing after exceeding a predetermined threshold voltage (reference voltage) Vs is set as the target zero crossing time Z, This zero-cross time Z is often used to calculate the propagation time t (=t1 or t2) from the transmission start timing ts of the ultrasonic signal to the reception timing tr.

The zero-crossing time Z is considered to exist after a predetermined time dly with respect to the reception timing tr. Therefore, by subtracting the predetermined time dly from the zero-crossing time Z, the propagation time t is obtained.
t=Z-dly (5)

The predetermined time dly is calculated in advance as the difference between the ideal propagation time (calculated by dividing the propagation path length by the speed of sound) and the target zero-crossing time Z. FIG.

Further, in the example shown in FIG. 14, the amplitude value P3 of the third wave S3 in the waveform (received waveform) indicating the change in the signal value of the received signal is set as the target peak, and the target peak and the second wave in the received waveform A threshold voltage Vs for propagation time measurement is defined between the amplitude value (pre-target peak) P2 of S2.

Japanese Patent No. 5228462

However, such an ultrasonic flowmeter has a problem that it takes time and effort to set the threshold voltage Vs at an appropriate level for target peaks having individual differences in intensity.

That is, the actual received waveform is affected by the individual differences of fluids and elements, etc., and the signal intensity is biased. Therefore, unless the received waveform is actually measured, the position of the target peak cannot be determined, and the correct threshold voltage Vs cannot be set accordingly. Manually grasping the target peak and setting the threshold voltage Vs is complicated and time-consuming.

The present invention has been made to solve such problems, and the object thereof is to provide an ultrasonic flowmeter capable of efficiently grasping a target peak and a peak height in the ultrasonic flowmeter. An object of the present invention is to provide an information acquisition method.

In order to achieve such an object, the present invention comprises a pipe (1) through which a fluid to be measured flows, a first ultrasonic transmitter/receiver (2) arranged upstream of this pipe, and a pipe downstream of the pipe. a second ultrasonic transmitter/receiver (3) positioned in the In an ultrasonic flow meter (100) configured to perform a plurality of steps and measure the flow rate of a fluid based on the propagation time difference of the ultrasonic signals in both directions obtained for each of these measurement steps, an ultrasonic signal and a predicted amplitude value (P) of a predetermined wave (S) in the received waveform, partially in the amplitude direction of the received waveform. Set a search range (W) of a predetermined width including A peak height information acquisition unit configured to obtain the timing at which the received waveform first crosses the threshold value, and to obtain the actual value of the amplitude value of the predetermined wave as peak height information based on the obtained timing. (42) is provided.

Further, the present invention comprises a pipe (1) through which a fluid to be measured flows, a first ultrasonic transmitter/receiver (2) arranged upstream of the pipe, and a second ultrasonic transmitter/receiver (2) arranged downstream of the pipe. an ultrasonic transmitter/receiver (3), performing a plurality of measurement steps of transmitting/receiving ultrasonic signals in both directions through a fluid between the first ultrasonic transmitter/receiver and the second ultrasonic transmitter/receiver; A method for obtaining peak height information in an ultrasonic flowmeter (100) configured to measure the flow rate of a fluid based on the propagation time difference of ultrasonic signals in both directions obtained for each of these measurement steps, comprising: A received waveform measurement step (step S103) of measuring a received waveform of a sound wave signal, and a predicted amplitude value (P) of a predetermined wave (S) in the received waveform partially in the amplitude direction of the received waveform. A search range (W) having a predetermined width is set, and the received waveform is repeatedly measured by the received waveform measurement step while changing the threshold value (Vth) within this search range. A peak height information acquisition step (S101 to S108) for obtaining the timing at which the waveform first crosses the threshold value and obtaining the actual value of the amplitude value of the predetermined wave as peak height information based on the obtained timing. It is characterized by

In the present invention, a search range of a predetermined width including the predicted amplitude value of a predetermined wave in the received waveform is partially set in the amplitude direction of the received waveform, and the received waveform is detected while changing the threshold value within this search range. is repeatedly executed, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the actual value of the amplitude value of the predetermined wave is peaked. Acquired as height information.

That is, in the present invention, the measurement of the received waveform is repeatedly executed while changing the threshold value only within a search range of a predetermined width partially set in the amplitude direction of the received waveform, instead of the entire range in the amplitude direction of the received waveform. Each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the actual value of the amplitude value of the predetermined wave is obtained as peak height information.

As a result, the range of changing the threshold (the range of setting the threshold) is narrowed and the number of times of changing the threshold (the number of thresholds to be set) is reduced compared to the method that uses the entire range of the amplitude direction of the received waveform as the search range. By doing so, it is possible to efficiently grasp the target peak by reducing the number of times the received waveform is measured.

In the present invention, for example, the predicted amplitude value (P1 ) is set, and the received waveform is repeatedly measured by the received waveform measuring unit while changing the threshold value (Vth) within this search range. , the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the actual value of the amplitude value (P1) of the minimum amplitude wave (S1) is obtained as peak height information, and this obtaining A search range (W2) having a predetermined width including the amplitude value (P2) of the next wave (S2) predicted from the peak height information obtained is partially set in the amplitude direction of the received waveform. The received waveform is repeatedly measured by the received waveform measurement unit while changing (Vth), and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing. to obtain the actual value of the amplitude value (P1) of the next wave (S2) as peak height information.

As a result, the actual value of the amplitude value (P) of the subsequent wave (S) is similarly obtained as peak height information, and the amplitude value (target peak) of the target wave (S3) is obtained. and set the optimum threshold voltage (Vs) for propagation time measurement between the grasped target peak and the amplitude value (pre-target peak) of the wave (S2) before the target wave. It becomes possible to

Further, in the present invention, for example, a representative value (for example, Pmax) of the amplitude of the received waveform measured by the received waveform measuring unit is obtained, and a predetermined wave (S2) in the received waveform predicted from the representative value of the amplitude is obtained. A search range (W2) having a predetermined width including the amplitude value (P2) of is partially set in the amplitude direction of the received waveform, and the received waveform is measured by the received waveform measurement unit while changing the threshold value (Vth) within this search range. is repeatedly executed, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the amplitude value (P2) of the predetermined wave (S2) is calculated. An actual value is acquired as peak height information, and a search range (W3) having a predetermined width including the amplitude value (P3) of the next wave (S3) predicted from the acquired peak height information is searched in the amplitude direction of the received waveform. , the received waveform is repeatedly measured by the received waveform measurement unit while changing the threshold (Vth) within the search range, and each time the received waveform is measured, the received waveform is set to the threshold and the first and the actual value of the amplitude value (P3) of the next wave (S3) is obtained as peak height information based on the obtained timing.

As a result, for example, the predetermined wave (S2) is set as the wave before the target wave, and the next wave (S3) is set as the target wave, and the amplitude value ( target peak), and set the optimum threshold voltage (Vs) for propagation time measurement between the target peak and the amplitude value (pre-target peak) of the wave before the target wave (S2). It becomes possible to

In the above description, as an example, constituent elements on the drawings corresponding to constituent elements of the invention are indicated by parenthesized reference numerals.

As described above, according to the present invention, a search range having a predetermined width including the predicted amplitude value of a predetermined wave in the received waveform is partially set in the amplitude direction of the received waveform, and this search range The measurement of the received waveform is repeated while changing the threshold within the received waveform, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold is obtained, and based on the obtained timing, the predetermined wave is detected. Since the actual value of the amplitude value of is obtained as peak height information, the range for setting the threshold is narrower than the method that uses the entire range in the amplitude direction of the received waveform as the search range. , and the number of times the received waveform is measured, it is possible to efficiently grasp the target peak.

FIG. 1 is a diagram explaining the principle of the first example of the present invention. FIG. 2 is a diagram explaining the principle of the second example of the present invention. FIG. 3 is a diagram showing a main part of an ultrasonic flowmeter according to an embodiment of the invention. FIG. 4 is a diagram showing an outline of the hardware configuration of the flow rate computing device in this ultrasonic flowmeter. FIG. 5 is a flow chart for explaining a first example (embodiment 1) of the processing operation executed by the CPU of the flow computing device in this ultrasonic flowmeter. FIG. 6 is a flowchart following FIG. FIG. 7 is a flow chart for explaining a second example (embodiment 2) of the processing operation executed by the CPU of the flow rate computing device in this ultrasonic flowmeter. FIG. 8 is a flowchart following FIG. FIG. 9 is a functional block diagram of the main part of the flow rate computing device in this ultrasonic flowmeter. FIG. 10 is a functional block diagram of a main part of a peak height information acquisition unit in the flow rate computing device of the ultrasonic flowmeter of Embodiment 1. FIG. FIG. 11 is a functional block diagram of a main part of a peak height information acquiring unit in the flow rate computing device of the ultrasonic flowmeter of Embodiment 2. FIG. FIG. 12 is a schematic diagram of an ultrasonic flowmeter. FIG. 13 is a waveform diagram (schematic diagram) of forward and backward received signals output from the ultrasonic transmitter/receiver. FIG. 14 is a diagram showing transmission signals and reception signals output from an ultrasonic transmitter/receiver. FIG. 15 is a diagram for explaining the technology that is the first stage of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, before starting the description of the embodiment, the technique that is the first stage of the present invention will be described using FIG. 15 .

[Technology that precedes the present invention]
In the ultrasonic flowmeter, as described with reference to FIG. 12, measurement is performed by transmitting/receiving ultrasonic signals in both directions through fluid between the first ultrasonic transmitter/receiver 2 and the second ultrasonic transmitter/receiver 3. The process is performed a plurality of times, and the flow rate Q is obtained based on the propagation time difference of the ultrasonic signals in both directions obtained for each of these measurement processes. In this case, the received waveforms as shown in FIG. 15 are measured in both the forward direction and the reverse direction for each measurement process that is performed multiple times.

In the technology that is the first stage of the present invention, in this ultrasonic flowmeter, the entire range in the amplitude direction of the received waveform (in the example shown in FIG. 15, the entire range in the amplitude direction on the positive side) is set as the search range. The measurement is repeated while changing the threshold value Vth to obtain the timing at which the received waveform first crosses the threshold value Vth, and based on the obtained timing, the amplitude value P of the wave S in the received waveform is obtained.

In this case, the threshold Vth is gradually increased each time the received waveform is measured, the timing at which the received waveform first crosses the threshold Vth is obtained, and the next zero-crossing timing after this timing is the zero-crossing time. Z is detected, and the threshold value Vth at the point where the zero-crossing time Z is greatly shifted is obtained as the amplitude value P of the wave S in the received waveform.

In the example shown in FIG. 15, the threshold Vth at the point where the zero-crossing time Z is first significantly shifted is acquired as the amplitude value P1 of the first wave S1, and then the threshold Vth at the point where the zero-crossing time Z is significantly shifted is the second. is acquired as the amplitude value P2 of the wave S2 of . Similarly, the threshold Vth at the point where the next zero-crossing time Z is greatly shifted is obtained as the amplitude value P3 of the third wave S3, and the threshold Vth at the next point where the zero-crossing time Z is greatly shifted is obtained as the fourth wave S4. is obtained as the amplitude value P4 of .

After obtaining the amplitude values P1 to P4 of the waves S1 to S4 in the received waveform in this manner, the threshold voltage Vs for measuring the propagation time is determined from the obtained amplitude values P1 to P4 of the waves S1 to S4. In this example, the amplitude value P3 of the third wave S3 in the received waveform is the target peak, the amplitude value P3 of the second wave S2 in the received waveform is the pre-target peak, and the interval between the target peak P3 and the pre-target peak P2 is determines the optimum threshold voltage Vs for propagation time measurement.

[Problems of the technology that precedes the present invention]
However, in this technique, since the entire range in the amplitude direction of the received waveform is used as the search range, the range in which the threshold Vth is set is wide, the number of thresholds Vth to be set is large, and the number of times the received waveform is measured is large. do. For this reason, it takes time to grasp the target peak, and power consumption also increases.

[Principle of the present invention]
Next, the principle of the present invention will be explained. In the present invention, a search range W having a predetermined width including the predicted amplitude value of a predetermined wave S in the received waveform is partially set in the amplitude direction of the received waveform, and the threshold value Vth is set within this search range W. The measurement of the received waveform is repeated while changing the received waveform, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value Vth is obtained, and based on the obtained timing, the amplitude of the predetermined wave S is obtained. The actual value of the value P is acquired as peak height information.

That is, in the present invention, the measurement of the received waveform is repeatedly executed while changing the threshold value Vth only within the search range W partially set in the amplitude direction of the received waveform, not the entire range in the amplitude direction of the received waveform, Each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value Vth is obtained, and based on the obtained timing, the actual value of the amplitude value P of the predetermined wave S is obtained as peak height information. .

As a result, the range of changing the threshold Vth (the range of setting the threshold) is narrowed, and the number of times the threshold Vth is changed (the number of thresholds Vth to be set) is narrowed compared to the method of setting the entire range in the amplitude direction of the received waveform as the search range. ) and the number of times the received waveform is measured, it becomes possible to efficiently grasp the target peak. It becomes possible to set the voltage Vs. In addition, by checking the actual shape of the received signal and setting the threshold voltage Vs according to the individual characteristic difference of the ultrasonic flowmeter, it is possible to measure the correct propagation time and obtain an accurate flow rate. It becomes possible to realize an ultrasonic flowmeter that can be

[First example of the present invention]
In the present invention, for example, as a first example, as shown in FIG. 1, the first wave in the received waveform (first wave: peak height information is obtained) is partially in the amplitude direction of the received waveform. A search range W1 having a predetermined width including the predicted amplitude value P1 of the wave S1 having the smallest amplitude among the waves S1 is set, and measurement of the received waveform is repeatedly executed while changing the threshold value Vth within the search range W1. Each time the waveform is measured, the timing at which the received waveform first crosses the threshold value Vth is obtained, and based on the obtained timing, the actual value of the amplitude value P1 of the first wave S1 is obtained as peak height information.

Then, a search range W2 having a predetermined width including the amplitude value P2 of the next wave (second wave) S2 predicted from the acquired peak height information (actual value of the amplitude value P1) is set in the amplitude direction of the received waveform. By partially setting the threshold Vth within the search range W2, measurement of the received waveform is repeatedly executed while changing the threshold Vth, and the timing at which the received waveform first crosses the threshold Vth is obtained every time the measurement of the received waveform is performed. , the actual value of the amplitude value P2 of the next wave S2 is acquired as the peak height information based on the obtained timing.

As a result, the actual values of the amplitude values P (P3, P4) of the subsequent waves S (S3, S4) are similarly acquired as peak height information, and the amplitude value P3 of the third wave S3 The actual value is the amplitude value of the target wave (target peak), the actual value of the amplitude value P2 of the second wave S2 is the amplitude value of the wave before the target wave (pre-target peak), and the target peak ( It is possible to set the optimum threshold voltage Vs for propagation time measurement between the actual value of the amplitude value P3) and the pre-target peak (the actual value of the amplitude value P2).

[Second example of the present invention]
In the present invention, as a second example, for example, as shown in FIG. 2, the maximum amplitude Pmax (in this example, P4=Pmax) is obtained as a representative value of the amplitude of the received waveform, and the received waveform predicted from this maximum amplitude Pmax A search range W2 having a predetermined width that includes the amplitude value P2 of the second wave S2 in is partially set in the amplitude direction of the received waveform, and measurement of the received waveform is repeatedly executed while changing the threshold value Vth within this search range W2. , each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value Vth is obtained, and based on the obtained timing, the actual value of the amplitude value P2 of the second wave S2 is obtained as peak height information. to get as

Then, a search range W3 having a predetermined width including the amplitude value P3 of the next wave (third wave) S3 predicted from the acquired peak height information (actual value of the amplitude value P2) is set in the amplitude direction of the received waveform. By partially setting the threshold Vth within the search range W3, measurement of the received waveform is repeatedly executed while changing the threshold Vth, and the timing at which the received waveform first crosses the threshold Vth is obtained each time the measurement of the received waveform is performed. , the actual value of the amplitude value P3 of the third wave S3 is obtained as the peak height information based on the obtained timing.

As a result, the amplitude value (target peak) of the target wave is the actual value of the amplitude value P3 of the third wave S3, and the actual value of the amplitude value P2 of the second wave S2 is the peak value of the wave before the target wave. Using the amplitude value (pre-target peak), between the target peak (actual value of the amplitude value P3) and the pre-target peak (actual value of the amplitude value P2), the optimal threshold voltage Vs can be set.

In the present invention, based on the timing at which the received waveform first crosses the threshold value Vth, the actual value of the amplitude value P of the predetermined wave S is obtained as peak height information. In this case, the timing at which the received waveform first crosses the threshold Vth is obtained, the next zero-crossing timing after this timing is detected as the zero-crossing time Z, and the threshold Vth at the point where the zero-crossing time Z is greatly shifted is determined. The amplitude value P of the wave S may be obtained, or the timing at which the received waveform first crosses the threshold value Vth is obtained, and the threshold value Vth at the point where this timing is greatly shifted is obtained as the amplitude value P of the wave S. You may do so.

In addition, in the present invention, as a method of searching for peak height information within the search range W, general methods for extremum and boundary search such as "binary search method", "three-way search method", and "golden search method" are used. It is possible to use a division method or the like.

In the simplest "binary search method", a threshold Vth is set to a total of three values at both ends of the search range W and its center, and the timing at which the threshold Vth and the received waveform intersect is compared. By determining in which of the two regions the peak exists, and repeating the same operation for the region with the peak until sufficient accuracy is obtained, the voltage at the peak apex is clarified.

Further, in the present invention, the search range W is partially set in the amplitude direction of the received waveform, but the amplitude direction of the received waveform may be on the plus side or the minus side. Also, it may be in both the positive and negative amplitude directions. That is, the acquisition of peak height information may be the amplitude value of the wave on the positive side, the amplitude value of the wave on the negative side, or the amplitude value of the wave on both the positive and negative sides. good too.

Further, in the present invention, the search range W is partially set in the amplitude direction of the received waveform, and the actual value of the amplitude value P of the predetermined wave S is acquired as the peak height information. The information does not necessarily have to be used for setting the threshold voltage Vs for measuring the propagation time, and may be used for setting other parameters.

[Embodiment]
FIG. 3 shows a main part of an ultrasonic flowmeter 100 according to an embodiment of the invention. In the figure, the same reference numerals as in FIG. 12 denote the same or equivalent components as those described with reference to FIG. 12, and the description thereof will be omitted.

In this ultrasonic flowmeter 100, for the first ultrasonic transmitter/receiver (upstream transducer) 2 and the second ultrasonic transmitter/receiver (downstream transducer) 3, "first ultrasonic transmitter/receiver 2 and A measurement step of transmitting and receiving ultrasonic signals in both directions through fluid between the second ultrasonic transmitter/receiver 3 is performed a plurality of times, and based on the propagation time difference of the ultrasonic signals in both directions obtained for each measurement step A flow rate calculation device 4 is provided which measures the flow velocity v of the fluid using the flow velocity v and obtains the flow rate Q of the fluid from the measured flow velocity v and the cross-sectional area S of the pipe 1 .

As shown in FIG. 4, the flow rate calculation device 4 includes a central processing unit (CPU) 4-1, a random access memory (RAM) 4-2, a read-only memory (ROM) 4-3, and a hard disk. It comprises a storage device 4-4, input/output interfaces 4-5 and 4-6, and a bus line 4-7 connecting them.

A threshold voltage setting program is installed in the flow rate calculation device 4 as a program unique to the present embodiment. This threshold voltage setting program is provided in a state recorded in a recording medium such as a CD-ROM. installed on.

In this flow rate calculation device 4, the CPU 4-1 processes the input information via the interface 4-5, and accesses the RAM 4-2, ROM 4-3, and storage device 4-4 while installing the It operates according to the threshold voltage setting program. A first example (embodiment 1) of the processing operation executed by the CPU 4-1 according to the threshold voltage setting program will be described below with reference to the flowcharts divided into FIGS. 5 and 6. FIG.

[Embodiment 1]
First, the CPU 4-1 searches a predetermined width search range including the predicted amplitude value P1 of the first wave (first wave) S1 in the received waveform (see FIG. 1) partially in the amplitude direction. W1 is set (step S101).

Then, the CPU 4-1 sets a threshold value Vth as a value lower than the predicted value of the amplitude value P1 within the search range W1 (step S102), and measures the received waveform while comparing it with the set threshold value Vth. (Steps S103 and S104).

In the measurement of the received waveform, if the received waveform exceeds the threshold value Vth, that is, if the received waveform first crosses the threshold value Vth (YES in step S104), the CPU 4-1 determines the timing of the next zero crossing after that. It is detected as time Z (step S105).

If the zero-crossing time Z detected this time has not greatly changed from the zero-crossing time Z detected last time (NO in step S106), the CPU 4-1 sets the threshold value Vth=Vth+α (step S107), and steps S102 to S106. repeat the process. When comparing with the first threshold value Vth within the search range W1, the zero-crossing time Z detected this time is assumed to be the same as the zero-crossing time Z detected last time (NO in step S106). return.

When the CPU 4-1 confirms that the zero-crossing time Z detected this time has greatly changed from the zero-crossing time Z detected last time (YES in step S106) during the repetition of the processing of steps S102 to S106, the threshold at that time Let Vth be the actual value of the amplitude value P1 of the first wave S1 (step S108).

Then, the CPU 4-1 sets N=1 (step S109) and sets a predetermined value including the amplitude value P2 of the next wave (second wave) S2 predicted from the amplitude value P1 of the first wave S1 obtained in step S108. A width search range W2 is partially set in the amplitude direction of the received waveform (step S110).

Then, the CPU 4-1 sets the threshold value Vth within the search range W2 as a value lower than the predicted value of the amplitude value P2 (step S111), and measures the received waveform while comparing it with the set threshold value Vth. (Steps S112 and S113).

In the measurement of the received waveform, if the received waveform exceeds the threshold value Vth, that is, if the received waveform first crosses the threshold value Vth (YES in step S113), the CPU 4-1 determines the timing of the next zero crossing after that. It is detected as time Z (step S114).

If the zero-crossing time Z detected this time has not greatly changed from the zero-crossing time Z detected last time (NO in step S115), the CPU 4-1 sets the threshold value Vth=Vth+α (step S116), and steps S111 to S115. repeat the process. When comparing with the first threshold value Vth within the search range W2, the zero-crossing time Z detected this time is assumed to be the same as the zero-crossing time Z detected last time (NO in step S115). return.

When the CPU 4-1 confirms that the zero-crossing time Z detected this time has greatly changed from the zero-crossing time Z detected last time (YES in step S115) during the repetition of the processing of steps S111 to S115, the threshold at that time Let Vth be the actual value of the amplitude value P2 of the second wave S2 (step S117).

Then, the CPU 4-1 sets N=N+1 (step S118), and repeats the processing of steps S110 to S118 until it is confirmed in step S119 that N=4. That is, for the next wave (third wave) S3 and the next wave (fourth wave) S4, a predetermined width search including the amplitude values P3 and P4 predicted from the actual values of the amplitude values P2 and P3 is performed. Ranges W3 and W4 are set, and every time the received waveform is measured while changing the threshold Vth within the search ranges W3 and W4, the timing at which the received waveform first crosses the threshold Vth is obtained to detect the zero-crossing time Z. Then, based on the detected zero-cross time Z, the actual value of the amplitude value P3 of the third wave S3 and the actual value of the amplitude value P4 of the fourth wave S4 are obtained.

When the CPU 4-1 confirms that N=4 (YES in step S119), the actual value of the amplitude value P3 is set as the target peak, and the actual value of the amplitude value P2 is set as the pre-target peak (step S120). , the optimum threshold voltage Vs for propagation time measurement is set between the target peak (actual value of amplitude value P3) and the pre-target peak (actual value of amplitude value P2) (step S121).

[Embodiment 2]
Next, a second example (embodiment 2) of the processing operation executed by the CPU 4-1 according to the threshold voltage setting program will be described with reference to the flow charts divided into FIGS. 7 and 8. FIG.

The CPU 4-1 first measures the received waveform (see FIG. 2) (step S201) and obtains the maximum amplitude Pmax of the measured received waveform (step S202). Then, a search range W2 having a predetermined width including the amplitude value P2 of the second wave S2 in the received waveform predicted from the maximum amplitude Pmax is partially set in the amplitude direction of the received waveform (step S203).

Then, the CPU 4-1 sets a threshold value Vth within the search range W2 as a value lower than the predicted value of the amplitude value P2 (step S204), and measures the received waveform while comparing it with the set threshold value Vth. (Steps S205 and S206).

In the measurement of the received waveform, if the received waveform exceeds the threshold value Vth, that is, if the received waveform first crosses the threshold value Vth (YES in step S206), the CPU 4-1 determines the timing of the next zero crossing after that. It is detected as time Z (step S207).

If the zero-crossing time Z detected this time has not greatly changed from the zero-crossing time Z detected last time (NO in step S208), the CPU 4-1 sets the threshold value Vth=Vth+α (step S209), and steps S204 to S208. repeat the process. When comparing with the first threshold value Vth within the search range W2, the zero-crossing time Z detected this time is assumed to be the same as the zero-crossing time Z detected last time (NO in step S208). return.

When the CPU 4-1 confirms that the zero-crossing time Z detected this time has greatly changed from the zero-crossing time Z detected last time (YES in step S208) during the repetition of the processing of steps S204 to S208, the threshold at that time Let Vth be the actual value of the amplitude value P2 of the second wave S2 (step S210).

Then, the CPU 4-1 receives a search range W3 of a predetermined width including the amplitude value P3 of the next wave (third wave) S3 predicted from the amplitude value P2 of the second wave S2 obtained in step S210. It is partially set in the amplitude direction of the waveform (step S211).

Then, the CPU 4-1 sets the threshold value Vth within the search range W3 as a value lower than the predicted value of the amplitude value P3 (step S212), and measures the received waveform while comparing it with the set threshold value Vth. (Steps S213 and S214).

In the measurement of the received waveform, if the received waveform exceeds the threshold value Vth, that is, if the received waveform first crosses the threshold value Vth (YES in step S214), the CPU 4-1 determines the timing of the next zero crossing after that. It is detected as time Z (step S215).

If the zero-crossing time Z detected this time has not greatly changed from the zero-crossing time Z detected last time (NO in step S216), the CPU 4-1 sets the threshold value Vth=Vth+α (step S217), and steps S212 to S216. repeat the process. When comparing with the first threshold value Vth within the search range W3, the zero-crossing time Z detected this time is assumed to be the same as the zero-crossing time Z detected last time (NO in step S216). return.

When the CPU 4-1 confirms that the zero-crossing time Z detected this time has greatly changed from the zero-crossing time Z detected last time (YES in step S216) during the repetition of the processing of steps S212 to S216, the threshold at that time Let Vth be the actual value of the amplitude value P3 of the third wave S3 (step S218).

Then, the CPU 4-1 sets the actual value of the amplitude value P3 as a target peak and the actual value of the amplitude value P2 as a pre-target peak (step S219). An optimum threshold voltage Vs for propagation time measurement is set between the actual value of the value P2 (step S220).

FIG. 9 shows a functional block diagram of the main part of the flow rate computing device 4 in the ultrasonic flowmeter 100. As shown in FIG. The flow rate calculation device 4 includes a received waveform measurement section 41, a peak height information acquisition section 42, and a propagation time measurement threshold voltage determination section 43 as processing functions of the CPU 4-1. The received waveform measuring unit 41, the peak height information acquiring unit 42, and the propagation time measuring threshold voltage determining unit 43 are provided for each of the forward/reverse direction received signals.

In the flow calculation device 4, the received waveform measurement unit 41 measures the received waveform of the ultrasonic signal, and the peak height information acquisition unit 42 measures at least the second wave in the received waveform measured by the received waveform measurement unit 41. The actual value of the amplitude value P2 of S2 and the actual value of the amplitude value P3 of the third wave S3 are detected as peak height information, and the propagation time measurement threshold voltage determination unit 43 acquires the peak height information acquisition unit 42. Based on the obtained peak height information, the optimum threshold voltage Vs for propagation time measurement is determined.

FIG. 10 shows a functional block diagram of the main part of the peak height information acquiring section 42 (42A) in the first embodiment. The peak height information acquisition unit 42A includes a search range setting unit 42A_1, a threshold setting unit 42A_2, a threshold comparison unit 42A_3, a zero cross time detection unit 42A_4, a previous zero cross time storage unit 42A_5, and a zero cross time comparison unit 42A_6. and an actual amplitude value determination unit 42A_7.

In the peak height information acquisition unit 42A, the search range setting unit 42A_1 partially includes the predicted amplitude value P1 of the first wave (first wave) S1 in the received waveform in the amplitude direction of the received waveform. A search range W1 having a predetermined width is set, and the set search range W1 is sent to the threshold value setting section 42A_2.

The threshold setting unit 42A_2 determines the threshold Vth as a value lower than the predicted value of the amplitude value P1 within the search range W1 from the search range setting unit 42A_1, and sets it to the threshold comparison unit 42A_3. When the threshold value Vth is set, the threshold comparison unit 42A_3 causes the reception waveform measurement unit 41 to start measuring the reception waveform, and compares the measured reception waveform (the reception waveform that changes every moment) with the threshold value Vth. .

When the received waveform exceeds the threshold Vth, that is, when the received waveform crosses the threshold Vth for the first time, the threshold comparator 42A_3 notifies the zero-crossing time detector 42A_4. The zero-crossing time detection unit 42A_4 receives the notification from the threshold value comparison unit 42A_3 and detects the next zero-crossing timing after receiving the notification as the zero-crossing time Z.

The zero-crossing time Z detected by the zero-crossing time detecting section 42A_4 is sent as the current zero-crossing time Z to the zero-crossing time comparing section 42A_6 and compared with the previous zero-crossing time Z stored in the previous zero-crossing time storage section 42A_5. be.

The zero-crossing time storage unit 42A_5 stores the current zero-crossing time Z detected by the zero-crossing time detecting unit 42A_4 as the previous zero-crossing time Z only when the search range is set by the search range setting unit 42A_1. be. After that, the previous zero-crossing time Z detected by the zero-crossing time detecting section 42A_4 is stored as the previous zero-crossing time Z. FIG.

The zero-crossing time comparing section 42A_6 compares the current zero-crossing time Z detected by the zero-crossing time detecting section 42A_4 with the previous zero-crossing time Z stored in the zero-crossing time storage section 42A_5. If there is no significant change with respect to the zero-crossing time Z (small change), the threshold Vth from the threshold setting section 42A_2 to the threshold comparison section 42A_3 is changed to Vth=Vth+α.

When the threshold value Vth is changed, the threshold comparison unit 42A_3 causes the received waveform measurement unit 41 to start measuring the received waveform, and compares the measured received waveform (the received waveform that changes every moment) with the changed threshold value Vth. make a comparison. Then, when the received waveform exceeds the threshold value Vth, the zero-crossing time detecting section 42A_4 is notified of this fact. As a result, the detection of the zero-crossing time Z by the zero-crossing time detecting section 42A_4, the comparison of the zero-crossing time Z by the zero-crossing time comparing section 42A_6, and the change of the threshold Vth by the threshold setting section 42A_2 are repeated.

When the current zero-crossing time Z greatly changes (changes greatly) from the previous zero-crossing time Z, the zero-crossing time comparing section 42A_6 notifies the actual amplitude value determining section 42A_7 of that effect. Upon receiving the "large change" notification from the zero-crossing time comparison unit 42A_6, the actual amplitude value determination unit 42A_7 determines the threshold value Vth in the threshold value setting unit 42A_2 at that time as the actual value of the amplitude value P1 of the first wave S1. .

The actual value of the amplitude value P1 of the first wave S1 determined by the actual amplitude value determining section 42A_7 is sent to the search range setting section 42A_1. The search range setting unit 42A_1 partially sets a predetermined width including the amplitude value P2 of the next wave (second wave) S2 predicted from the actual value of the amplitude value P1 of the first wave S1 in the amplitude direction of the received waveform. is set, and the set search range W2 is sent to the threshold value setting unit 42A_2.

The threshold setting unit 42A_2 determines a threshold Vth as a value lower than the predicted value of the amplitude value P2 within the search range W2 from the search range setting unit 42A_1, and sets it to the threshold comparison unit 42A_3. When the threshold value Vth is set, the threshold comparison unit 42A_3 causes the reception waveform measurement unit 41 to start measuring the reception waveform, and compares the measured reception waveform (the reception waveform that changes every moment) with the threshold value Vth. .

After that, similarly to the search range W1, the detection of the zero-cross time Z by the zero-cross time detection unit 42A_4, the comparison of the zero-cross time Z by the zero-cross time comparison unit 42A_6, and the change of the threshold Vth by the threshold setting unit 42A_2 are repeated. The actual value of the amplitude value P2 of the second wave S2 is determined in the actual amplitude value determining section 42A_7.

Subsequently, search ranges W3 and W4 are similarly set by the search range setting unit 42A_1, and the detection of the zero-cross time Z is repeated while changing the threshold value Vth within the search ranges W3 and W4. The actual value of the amplitude value P3 of the third wave S3 and the actual value of the amplitude value P4 of the fourth wave S4 are determined by the value determining section 42A_7.

FIG. 11 shows a functional block diagram of the main part of the peak height information acquiring section 42 (42B) in the second embodiment. The peak height information acquisition unit 42B includes a search range setting unit 42B_1, a threshold setting unit 42B_2, a threshold comparison unit 42B_3, a zero cross time detection unit 42B_4, a previous zero cross time storage unit 42B_5, and a zero cross time comparison unit 42B_6. , an actual amplitude value determination unit 42B_7, and a maximum amplitude acquisition unit 42B_8.

In the peak height information acquiring section 42B, the maximum amplitude acquiring section 42B_8 causes the received waveform measuring section 41 to measure the received waveform, and obtains the maximum amplitude Pmax of the measured received waveform. The maximum amplitude Pmax of the received waveform obtained by the maximum amplitude acquisition section 42B_8 is sent to the search range setting section 42B_1.

The search range setting unit 42B_1 predicts the amplitude value P2 of the second wave S2 in the received waveform from the maximum amplitude Pmax from the maximum amplitude acquisition unit 42B_8, and calculates the amplitude value P2 of the second wave S2 in the predicted received waveform. is partially set in the amplitude direction of the received waveform, and the set search range W2 is sent to the threshold value setting unit 42B_2.

The threshold setting unit 42B_2 determines the threshold Vth as a value lower than the predicted value of the amplitude value P2 within the search range W2 from the search range setting unit 42B_1, and sets the threshold Vth to the threshold comparison unit 42B_3. When the threshold value Vth is set, the threshold comparison unit 42B_3 causes the received waveform measurement unit 41 to start measuring the received waveform, and compares the measured received waveform (the received waveform that changes every moment) with the threshold value Vth. .

When the received waveform exceeds the threshold Vth, that is, when the received waveform crosses the threshold Vth for the first time, the threshold comparator 42B_3 notifies the zero-crossing time detector 42B_4. The zero-cross time detection unit 42B_4 receives the information from the threshold value comparison unit 42B_3 and detects the next zero-cross timing after receiving this information as the zero-cross time Z. FIG.

The zero-crossing time Z detected by the zero-crossing time detecting section 42B_4 is sent as the current zero-crossing time Z to the zero-crossing time comparing section 42B_6 and compared with the previous zero-crossing time Z stored in the previous zero-crossing time storage section 42B_5. be.

The zero-crossing time storage unit 42B_5 stores the current zero-crossing time Z detected by the zero-crossing time detecting unit 42B_4 as the previous zero-crossing time Z only when the search range is set by the search range setting unit 42B_1. be. After that, the previous zero-crossing time Z detected by the zero-crossing time detecting section 42B_4 is stored as the previous zero-crossing time Z. FIG.

The zero-cross time comparator 42B_6 compares the current zero-cross time Z detected by the zero-cross time detector 42B_4 with the previous zero-cross time Z stored in the zero-cross time storage 42B_5, and compares the current zero-cross time Z with the previous zero-cross time Z. If there is no significant change with respect to the zero-crossing time Z (small change), the threshold Vth from the threshold setting unit 42B_2 to the threshold comparison unit 42B_3 is changed to Vth=Vth+α.

When the threshold value Vth is changed, the threshold comparison unit 42B_3 causes the received waveform measurement unit 41 to start measuring the received waveform, and compares the measured received waveform (the received waveform that changes every moment) with the changed threshold value Vth. make a comparison. Then, when the received waveform exceeds the threshold value Vth, the zero-crossing time detecting section 42B_4 is notified of this fact. As a result, the detection of the zero-cross time Z by the zero-cross time detection unit 42B_4, the comparison of the zero-cross time Z by the zero-cross time comparison unit 42B_6, and the change of the threshold Vth by the threshold setting unit 42B_2 are repeated.

When the current zero-crossing time Z greatly changes (changes greatly) from the previous zero-crossing time Z, the zero-crossing time comparing section 42B_6 notifies the actual amplitude value determining section 42B_7. Upon receiving the "large change" notification from the zero-crossing time comparison unit 42B_6, the actual amplitude value determination unit 42B_7 determines the threshold value Vth in the threshold setting unit 42B_2 at that time as the actual value of the amplitude value P2 of the second wave S2. do.

The actual value of the amplitude value P2 of the second wave S2 determined by the actual amplitude value determining section 42B_7 is sent to the search range setting section 42B_1. The search range setting unit 42B_1 partially includes a predetermined amplitude value P3 of the next wave (third wave) S3 predicted from the actual value of the amplitude value P2 of the second wave S2 in the amplitude direction of the received waveform. A width search range W3 is set, and the set search range W3 is sent to the threshold setting unit 42B_2.

The threshold setting unit 42B_2 determines the threshold Vth as a value lower than the predicted value of the amplitude value P3 within the search range W3 from the search range setting unit 42B_1, and sets it to the threshold comparison unit 42B_3. When the threshold value Vth is set, the threshold comparison unit 42B_3 causes the received waveform measurement unit 41 to start measuring the received waveform, and compares the measured received waveform (the received waveform that changes every moment) with the threshold value Vth. .

After that, similarly to the search range W2, the detection of the zero-cross time Z by the zero-cross time detection unit 42B_4, the comparison of the zero-cross time Z by the zero-cross time comparison unit 42B_6, and the change of the threshold Vth by the threshold setting unit 42B_2 are repeated. The actual value of the amplitude value P3 of the third wave S3 is determined in the actual amplitude value determining section 42B_7.

In the examples shown in FIGS. 1 and 2, the widths of the search ranges W1, W2, W3, and W4 are the same, but the widths do not necessarily have to be the same. You may make it narrow and go. For the search ranges W1, W2, W3, and W4, values stored in advance may be used according to the shape of the received waveform at the time of shipping inspection. Alternatively, the search range may be determined by measuring the representative value of the amplitude of the received waveform and taking into consideration the effects of temperature measurement information and sound speed, which are factors that change the shape of the received waveform.

In addition, the above-described setting of the threshold voltage Vs for propagation time measurement by acquiring the peak height information may be performed when the ultrasonic flowmeter 100 is shipped from the factory, or may be performed normally after installation at the site. You may make it perform in the idle time between flow measurement.

In addition, in the case of an ultrasonic flowmeter that can recognize the reference peak for propagation time measurement in the received wave as a tracking target peak during normal flow measurement, and can grasp the height of the tracking target peak during flow measurement, Based on the height of the tracking target peak, set the search range for the peaks adjacent to the tracking target peak (the peak immediately before and after the tracking target peak), and grasp the heights of the peaks adjacent to the tracking target peak. You may make it As a result, the shape of the received waveform can be grasped in a short period of time during normal flow measurement, etc., and by adjusting the threshold value etc. according to the actual adjacent peak height, maintenance work can be reduced and work can be simplified. Labor can be reduced.

Also, when measuring in combination with the ±threshold, if the height of the peak on the positive side can be grasped in normal flow measurement, set the peak search range on the adjacent negative side accordingly, The height of the side peak may be grasped.

Also, set the search range of adjacent peaks based on the height of the peak currently being tracked (peak to be tracked) during the idle time between normal flow rate measurements, and check the peak height by peak search operation. By doing so, the heights of the tracking target peak and the peaks adjacent thereto may be grasped. If there is no sudden change in the flow rate, temperature, or propagation time during this search operation, it is determined that the correct peak has been grasped, and the information is used to set the threshold voltage for subsequent propagation time measurement (periodic automatic calibration).

Also, if the height of the peak to be tracked is known from the previous measurement during flow rate measurement and the position is lost, the search range for the peak to be tracked can be determined from the peak height and the maximum amplitude of the received waveform. It may be set to search for a peak to be tracked.

In addition, when there is variation in the intensity of the received waveform, the frequency of occurrence of exceeding the threshold Vth is used to determine the score at a certain threshold, instead of the binary value of whether the received waveform exceeds the threshold Vth or not, for example, the same threshold Vth may be measured 10 times, a score as a continuous value indicating how many times the threshold crossing timing has shifted may be obtained, and a search may be performed using a hill-climbing method or the like.

[Expansion of Embodiment]
Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the technical idea of the present invention.

1... Piping, 2... First ultrasonic transmitter/receiver (upstream transducer), 3... Second ultrasonic transmitter/receiver (downstream transducer), 4... Flow calculation device, 4-1... Central processing unit (CPU ), 4-2... Random access memory (RAM), 4-3... Dedicated memory (ROM), 4-4... Storage device, 4-5, 4-6... Interface, 4-7... Bus line, 41... Received waveform Measurement unit 42 (42A, 42B) ... peak height information acquisition unit 42A ... peak height information acquisition unit 42A_1, 42B_1 ... search range setting unit 42A_2, 42B_2 ... threshold setting unit 42A_3, 42B_3 ... threshold comparison unit , 42A_4, 42B_4 ... zero-cross time detection unit, 42A_5, 42B_5 ... zero-cross time storage unit, 42A_6, 42B_6 ... zero-cross time comparison unit, 42A_7, 42B_7 ... actual amplitude value determination unit, 42B_8 ... maximum amplitude acquisition unit, 43 ... propagation time Measurement threshold voltage determination unit 100... Ultrasonic flow meter.

Claims (6)

a pipe through which a fluid to be measured flows; a first ultrasonic transmitter/receiver arranged upstream of the pipe; and a second ultrasonic transmitter/receiver arranged downstream of the pipe; The measurement step of transmitting and receiving ultrasonic signals in both directions through the fluid between the ultrasonic transmitter and receiver of and the second ultrasonic transmitter and receiver is performed a plurality of times, and in the two directions obtained for each of these measurement steps In an ultrasonic flowmeter configured to measure the flow rate of the fluid based on the propagation time difference of the ultrasonic signal,
a received waveform measurement unit configured to measure a received waveform of the ultrasonic signal;
A search range of a predetermined width including a predicted amplitude value of a predetermined wave of the received waveform is partially set in the amplitude direction of the received waveform, and the received waveform measuring unit changes a threshold value within the search range. to repeatedly measure the received waveform by, each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the amplitude of the predetermined wave a peak height information acquisition unit configured to acquire the actual value of the value as peak height information,
The peak height information acquisition unit is
A search range of a predetermined width is set partially in the amplitude direction of the received waveform, including the predicted amplitude value of the wave with the smallest amplitude among the waves from which the peak height information is obtained in the received waveform. Then, the received waveform is repeatedly measured by the received waveform measuring unit while changing the threshold within the search range, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold is determined. obtaining, based on the obtained timing, obtaining the actual value of the amplitude value of the minimum amplitude wave as peak height information,
A search range of a predetermined width including the amplitude value of the next wave predicted from the acquired peak height information is partially set in the amplitude direction of the received waveform, and the received waveform is changed while changing the threshold within this search range. Measurement of the received waveform by the measuring unit is repeatedly performed, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the next wave is detected. An ultrasonic flowmeter characterized by acquiring an actual amplitude value as peak height information. a pipe through which a fluid to be measured flows; a first ultrasonic transmitter/receiver arranged upstream of the pipe; and a second ultrasonic transmitter/receiver arranged downstream of the pipe; The measurement step of transmitting and receiving ultrasonic signals in both directions through the fluid between the ultrasonic transmitter and receiver of and the second ultrasonic transmitter and receiver is performed a plurality of times, and in the two directions obtained for each of these measurement steps In an ultrasonic flowmeter configured to measure the flow rate of the fluid based on the propagation time difference of the ultrasonic signal,
a received waveform measurement unit configured to measure a received waveform of the ultrasonic signal;
A search range of a predetermined width including a predicted amplitude value of a predetermined wave of the received waveform is partially set in the amplitude direction of the received waveform, and the received waveform measuring unit changes a threshold value within the search range. to repeatedly measure the received waveform by, each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the amplitude of the predetermined wave a peak height information acquisition unit configured to acquire the actual value of the value as peak height information,
The peak height information acquisition unit is
A representative value of the amplitude of the received waveform measured by the received waveform measuring unit is obtained, and a search range of a predetermined width including an amplitude value of a predetermined wave in the received waveform predicted from the representative value of the amplitude is defined as the reception range. The received waveform is partially set in the amplitude direction of the waveform, and the received waveform is repeatedly measured by the received waveform measurement unit while changing the threshold value within the search range. Obtaining the timing of first crossing the threshold value, obtaining the actual value of the amplitude value of the predetermined wave based on the obtained timing as peak height information,
A search range of a predetermined width including the amplitude value of the next wave predicted from the acquired peak height information is partially set in the amplitude direction of the received waveform, and the received waveform is changed while changing the threshold within this search range. Measurement of the received waveform by the measuring unit is repeatedly performed, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the next wave is detected. An ultrasonic flowmeter characterized by acquiring an actual amplitude value as peak height information. In the ultrasonic flowmeter according to claim 1 or 2 ,
The peak height information acquisition unit is
The timing at which the received waveform first crosses the threshold value is obtained, the next zero-crossing timing after this timing is detected as a zero-crossing time, and the peak height information is obtained based on the detected zero-crossing time. An ultrasonic flowmeter characterized by: a pipe through which a fluid to be measured flows; a first ultrasonic transmitter/receiver arranged upstream of the pipe; and a second ultrasonic transmitter/receiver arranged downstream of the pipe; The measurement step of transmitting and receiving ultrasonic signals in both directions through the fluid between the ultrasonic transmitter and receiver of and the second ultrasonic transmitter and receiver is performed a plurality of times, and in the two directions obtained for each of these measurement steps A method for obtaining peak height information in an ultrasonic flowmeter that measures the flow rate of the fluid based on the propagation time difference of the ultrasonic signal,
a received waveform measuring step of measuring a received waveform of the ultrasonic signal;
A search range of a predetermined width including a predicted amplitude value of a predetermined wave in the received waveform is set partially in the amplitude direction of the received waveform, and the received waveform measurement step while changing the threshold value within the search range. to repeatedly measure the received waveform by, each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the amplitude of the predetermined wave a peak height information acquisition step of acquiring the actual value of the value as peak height information,
The peak height information acquisition step includes:
A search range of a predetermined width is set partially in the amplitude direction of the received waveform, including the predicted amplitude value of the wave with the smallest amplitude among the waves from which the peak height information is obtained in the received waveform. Then, while changing the threshold value within the search range, the received waveform measurement step is repeatedly performed, and each time the received waveform measurement is performed, the timing at which the received waveform first crosses the threshold value is determined. obtaining, based on the obtained timing, obtaining the actual value of the amplitude value of the minimum amplitude wave as peak height information,
A search range of a predetermined width including the amplitude value of the next wave predicted from the acquired peak height information is partially set in the amplitude direction of the received waveform, and the received waveform is changed while changing the threshold within this search range. The measurement of the received waveform is repeatedly performed by the measurement step, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and the next wave is determined based on the obtained timing. A method for acquiring peak height information in an ultrasonic flowmeter, comprising acquiring an actual amplitude value as peak height information. a pipe through which a fluid to be measured flows; a first ultrasonic transmitter/receiver arranged upstream of the pipe; and a second ultrasonic transmitter/receiver arranged downstream of the pipe; The measurement step of transmitting and receiving ultrasonic signals in both directions through the fluid between the ultrasonic transmitter and receiver of and the second ultrasonic transmitter and receiver is performed a plurality of times, and in the two directions obtained for each of these measurement steps A method for obtaining peak height information in an ultrasonic flowmeter that measures the flow rate of the fluid based on the propagation time difference of the ultrasonic signal,
a received waveform measuring step of measuring a received waveform of the ultrasonic signal;
A search range of a predetermined width including a predicted amplitude value of a predetermined wave in the received waveform is set partially in the amplitude direction of the received waveform, and the received waveform measurement step while changing the threshold value within the search range. to repeatedly measure the received waveform by, each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and based on the obtained timing, the amplitude of the predetermined wave a peak height information acquisition step of acquiring the actual value of the value as peak height information,
The peak height information acquisition step includes:
A representative value of the amplitude of the received waveform measured by the received waveform measuring step is obtained, and a search range having a predetermined width including an amplitude value of a predetermined wave in the received waveform predicted from the representative value of the amplitude is defined as the reception range. The received waveform is partially set in the amplitude direction of the waveform, and the received waveform is repeatedly measured by the received waveform measurement step while changing the threshold value within the search range. Obtaining the timing of first crossing the threshold value, obtaining the actual value of the amplitude value of the predetermined wave based on the obtained timing as peak height information,
A search range of a predetermined width including the amplitude value of the next wave predicted from the acquired peak height information is partially set in the amplitude direction of the received waveform, and the received waveform is changed while changing the threshold within this search range. The measurement of the received waveform is repeatedly performed by the measurement step, and each time the received waveform is measured, the timing at which the received waveform first crosses the threshold value is obtained, and the next wave is determined based on the obtained timing. A method for acquiring peak height information in an ultrasonic flowmeter, comprising acquiring an actual amplitude value as peak height information. In the method for acquiring peak height information in the ultrasonic flowmeter according to claim 4 or 5 ,
The peak height information obtaining step obtains the timing at which the received waveform first crosses the threshold value, detects the next zero-crossing timing after passing this timing as a zero-crossing time, and based on the detected zero-crossing time A method for acquiring peak height information in an ultrasonic flowmeter, characterized in that the peak height information is acquired by using an ultrasonic flowmeter.

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