JPH073348B2 - Method and apparatus for processing measured values of ultrasonic flowmeter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a measurement value processing method for an ultrasonic flowmeter and an apparatus therefor, and particularly an ultrasonic flow rate suitable for measuring a flow rate of a fluid in which bubbles and the like are easily mixed. TECHNICAL FIELD The present invention relates to a measurement value processing method and an apparatus thereof.

[Conventional technology]

As a method of processing measured values of an ultrasonic flow meter that has been widely used conventionally, for example, there is one disclosed in Japanese Patent Publication No. 59-14173. In this conventional example, first, the propagation times of the forward and backward ultrasonic waves that follow the fluid flow are detected, and then the reference level is set with respect to the lamp voltage formed corresponding to the level of this detection signal. The upper limit and the lower limit are set for each reference level, and if the limit is exceeded, it is determined as abnormal data. When the measured values are specifically adopted, both measured values are adopted only when the received signals in both the forward and backward directions are normal.

On the other hand, although not particularly disclosed in Japanese Patent Publication No. 59-14173, the waveforms of the received ultrasonic waves in the forward and reverse directions of the fluid to be measured are specifically shown in FIGS. 5 (1) (3). (4) A, B
There are various changes as shown in. For this reason, how to determine the arrival time of the ultrasonic wave based on which wave portion is an important issue in the precise measurement of the flow rate.

As being often employed conventionally defines a reception reference level S _L First, the specific point (zero cross point to the time when the first wave reaches to cross its center time axis (zero level) on the received reference level S _L ), There is a method of determining the arrival time of the received signal by using this specific point as a reference measurement point on the receiving side.

This will be described in more detail with reference to FIG. 5 described above. In FIG. 5, A indicates a reception signal (solid line) of ultrasonic waves in the forward direction along the flow of the fluid to be measured, and B indicates a reverse direction against the flow. The received signal (broken line) is shown. Of the received waveform, the first peak is the first wave, the valley following it is the second wave, the second peak is the third wave, the valley following it is the fourth wave, and so on. Wave 5 ... Then, these waveforms first intersect with the reception reference level S _L , for example, in FIG. 5 (1).
In the case of, the wave becomes the third wave, and the wave in this case progresses from the mountain to the valley to reach the zero level S _O , and the intersection point (zero cross point) is measured.

That is, in the case of FIG. 5 (1), the third wave of both the reception signals A and B exceeds the reception reference level S _L. In the case of (2) in the figure, the fifth wave exceeds the reception reference level S _L for both reception signals A and B, with the reception sensitivity generally deteriorated due to the inclusion of bubbles in the fluid. The state is different from that of FIG. Further, in the case of FIG. 5 (3), the received signal A in the forward direction is the third wave, and the received signal B in the reverse direction is the fifth wave, which exceed the reception reference level S _L , respectively. The situation is significantly different from, and is an abnormal phenomenon that often occurs during actual measurement.

[Problems to be solved by the invention]

Of the received signals in FIG. 5 described above, FIG. 5 (1) is normal. (2) in the figure is generated correspondingly due to the influence of bubbles flowing with the fluid to be measured, the voltage fluctuation of the power supply, the malfunction of the transmission system or the reception system of the device, and the like. Also, the one in (3) of the figure is a clear abnormal signal caused by the abnormality of the fluid to be measured (mostly the inclusion of bubbles).

With respect to such various received signals, in the conventional device, as is apparent from Japanese Patent Publication No. 59-14173, the received signals of the ultrasonic waves in the forward direction and the reverse direction of the fluid to be measured are individually taken out. In addition to checking for abnormalities, all the received signals are judged to be abnormal and discarded unless both are normal at the same time. For this reason, in the above-mentioned conventional example, among the received waveforms in (1), (3) and (4) of FIG.
Since the arrival time of the reception signal _{Tu (i + l) in} the reverse direction is clearly " _{Tu (i + l)} ≠ _{Tu (i + 2)} ≠ _{Tu (i + 3)} ",
If the values in FIG. 1 are normal values, all other values are judged to be abnormal values.

Therefore, in the above-mentioned conventional example, the probability of adopting the normal value is poor, and in some cases, the measurement is performed only once or less than three times, which is not only wasteful in measurement but also the reliability of the measurement result. There was an inconvenience that it was bad. Further, in order to compensate for this, it has been necessary to set a long measurement time and detect a large number of normal values, which causes a problem of poor response to changes in the flow velocity.

[Object of the Invention]

The present invention improves the inconveniences of the conventional example, in particular, it can judge the difference between the abnormal data and the change in the measured value due to the change in the flow velocity, and can sufficiently cope with the rapid change in the flow velocity. It is an object of the present invention to provide a measurement value processing method for an ultrasonic flow meter and a device therefor.

[Means for Solving Problems] In the present invention, after measuring the propagation time of ultrasonic waves in the forward direction and the reverse direction of the flow of the fluid to be measured, the difference between the propagation times of the ultrasonic waves in the two directions is calculated. In the measurement value processing method of the ultrasonic flowmeter that determines the flow rate of the fluid to be measured based on the calculated propagation time difference of the ultrasonic waves, the forward and backward ultrasonic wave propagation time differences of the fluid to be measured are A first data processing step of storing as the propagation time difference data; and a second data processing step of comparing the stored propagation time difference data with the latest propagation time difference data stored before that to obtain the difference. ing. Further, a third data processing step of counting the number of consecutive detections of the abnormal data when the difference between the old and new propagation time difference data is larger than a predetermined reference time difference data, and the number of consecutive detections of the abnormal data is predetermined. And a fourth data processing step in which a measured value obtained next to the latest abnormal data is adopted as normal data when the reference number of times is exceeded. This aims to achieve the above-mentioned object.

Example of Invention

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

First, FIG. 1 shows a case where the fluid to be measured is flowing in the tube 1 in the direction of arrow 2. The fluid to be measured 2 is attached to the tube 1.
Is divided into an upstream side and a downstream side with a certain interval, and as shown in the figure, the ultrasonic transducers are provided on the upper side and the lower side, respectively.
It is equipped with 3A and 3B. A transmission signal T is alternately sent from the transmission circuit 4 to the ultrasonic wave transmitters / receivers 3A and 3B as an excitation signal from the transmission circuit 4 every repeating period S.

That is, the transmission circuit 4 has a function of outputting the excitation signal T having a predetermined frequency and the switching signal S for the switching circuit 5 to the switching circuit 5. The switching circuit 5 is switched at the timing of a predetermined repeating cycle S shown in FIG. 2, and when one ultrasonic wave transmitter / receiver 3A is in the transmitting state, the other ultrasonic wave transmitter / receiver is used.
3B is set to receive state. An oblique dotted line P in the tubular body 1 indicates an ultrasonic wave propagation path.

Here, the reception signal R converted into an electric signal and output from the ultrasonic wave transmitter / receiver 3A or 3B is sent to the reception signal 6 via the switching circuit 5.

The received signal 6 is inputted with the received signal R and then amplified. At the same time, a built-in zero-cross pulse generator (not shown) generates pulse signals R'and R "to output them (see FIGS. 2 and 3). 5 (2)). These pulse signals R ', R "
Is input to the counter circuit 7 together with the transmission signal T which is the output signal from the transmission circuit 4 described above. C indicates the output of the counter circuit 7. That is, in this counter circuit 7,
A clock signal C'is first formed by the gate signal composed of the transmission signal T and the output signals R ', R "of the receiving circuit 6, and the count data which is the count value of this clock pulse C'is used as the counter output C in the arithmetic circuit. It is designed to be output to 8. Each of these signals and its timing chart are shown in FIG.

Here, the counter output C is a signal including information relating to the propagation time of each ultrasonic wave in the forward and backward directions of the fluid to be measured. Then, the arithmetic circuit 8 into which these pieces of information are input
In addition to the calculation of the flow rate, various calculations such as the flow velocity and the integrated flow rate can be performed, and thereafter, these can be output to the display means 40 and displayed.

As shown in FIG. 3, the arithmetic circuit 8 described above specifically includes an input / output interface circuit (l / OIFC) 8A, a central processing unit (CPU) 8B, and a read-only memory (ROM) in which a program is written. 8C, writable and readable memory for storing data and other command signals (RA
M) 8D and a clock oscillator (OSC) 8E that outputs a clock pulse that serves as a reference for calculation. Then, the arithmetic circuit 8 has a first
The counter circuit 7 is provided with the function shown in FIG.
On the other hand, on the other hand, the keyboard 9 is used to input setting values and the like required at the time of starting the calculation, to perform a predetermined calculation according to the flowchart shown in FIG. 4, and then to output the calculation result to the display means 12. ing.

Next, a specific signal processing procedure in the arithmetic circuit 8 will be described. In this arithmetic circuit 8, a first data processing step of storing the propagation time difference of the ultrasonic waves in the forward direction and the reverse direction of the flow of the fluid to be measured as the propagation time difference data, and the stored propagation time difference data are stored before that. The second data processing step of comparing the latest propagation time difference data to obtain the difference and the number of continuous detection of the abnormal data when the difference between the old and new propagation time difference data is larger than the predetermined reference time data. A third data processing step of counting the number of times, and a fourth measured value obtained after the latest abnormal data is adopted as normal data when the number of consecutive detections of this abnormal data exceeds a predetermined reference number. And a data processing step.

Then, each of these steps is performed with the following configurations and operations thereof. Hereinafter, this will be described in detail.

In FIG. 1, the counter output C input to the measurement data input means 10 has the same ultrasonic wave propagation time in the reverse direction as the signal T _{d (i + l)} representing the ultrasonic wave propagation time in the forward direction of the fluid to be measured. It has both data of the signal _{Tu (i + l)} representing. Here, "i = 0,1,2,3, ..., k, ... n", and (i
+1) indicates the number of times of (i + 1) th ultrasonic oscillation and reception in the repetition cycle.

The counter output C, that is, T _{d (i + l)} and T _{u (i + l)} is input for each forward and backward repeating period and stored in the storage means 11. A propagation time difference calculation unit 12 is installed in the storage unit 11. The propagation time calculation unit 12 reads out the data T _{d (i + l)} and T _{u (i + l)} temporarily stored in the storage means 11 and calculates the propagation time difference data ΔT _{(i + l)} . It is like this. This propagation time difference data ΔT _{(i + l)} is T
_{When d (i + l)} and _{Tu (i + l)} are normal data, they are officially stored in the storage means 11. The propagation time difference data ΔT _{(i + l)} to be stored in the storage means 11 is judged by the time difference comparison and judgment means 13 as to whether it is normal data or not. The propagation time difference data ΔT _{(i + l)} determined to be normal data is officially stored in the storage unit 11 until the next propagation time difference data ΔT _{(i + 2)} or ΔT _{(i + k)} is determined to be normal data. Memorized in.

The time difference comparison / determination means 13 includes a time difference comparison / calculation unit 13A, a reference setting unit 13B for outputting a reference value G of the propagation time difference data ΔT _{(i + l)} which is an output of the time difference comparison / calculation unit 13A, and a reference value G. It is configured by a comparison determination unit 13C that compares the propagation time difference data ΔT _{(i + l)} and outputs a predetermined control signal described later.

More specifically, first, the time difference comparison calculation unit 13A
Propagation time difference data ΔT _{(i + l)} to be stored in the storage means 11.
Is the normal data Δ stored in the storage means 11 before that.
Compare whether or not it is almost equal to T _(i) .

Therefore, the time difference comparison operation unit 13A reads out the propagation time difference data ΔT _{(i + l)} and the propagation time difference data ΔT _(i) stored before from the storage means 11 and compares the two, and The difference is output to the comparison / determination unit 13C. Comparison judgment unit 1
3C compares “| ΔT _{(i + l)} −ΔT _(i) |”, which is the calculation result in the time difference comparison calculation unit 13A, with the reference value G input from the reference value setting unit 13B, and calculates | │T _{(i When + l)} −ΔT _(i) | ≧ G, a write stop signal for stopping the writing of ΔT _{(i + l)} as abnormal data is output to the storage means 11, and the abnormal value counter 20A described later is walked. It has a function of outputting a step signal to advance.

Further, the comparison / determination unit 13C determines that the normal data is ΔT when the calculation result of the time difference comparison / calculation unit 11A is smaller than the reference value G, that is, | ΔT _{(i + l)} −ΔT _(i) | <G. A memory command signal for commanding the writing of _{(i + 1)} is output to the memory means 11, and at the same time,
It has a function of outputting a clear signal to the abnormal value counter 20A and an operation No. 111 to the flow velocity / flow rate operation unit 30.

Further, the comparison / determination unit 13C also has a function of changing the reference value G to G ′ or G ″ in response to an external command (however, G <G ′ <G ″).

A flow velocity change determination means 20 is provided side by side with the comparison determination unit 13C of the time difference comparison determination means 13. This flow velocity change determination means 20
Is a counter 20A that counts the number of continuous detection of abnormal values,
When the count value of the counter 20A exceeds the reference count value H, the reference value G is set to G'or G "in order to store the measurement value obtained next to the latest abnormal data as normal data due to the flow velocity change. A reference value change command for changing the reference value to the comparison / determination unit 13C, and an abnormality number comparison unit 20B that outputs a clear signal to the counter 20A and a reference number value H to the abnormality number comparison unit 20B. And a reference number setting unit 20C for sending the signal relating to.

The flow velocity / flow rate calculation unit 30 operates when a calculation command signal is output from the time difference comparison / determination unit 13, immediately starts a predetermined calculation based on the propagation time difference data sent from the storage unit 11, and the propagation time difference data ΔT _It has a function of calculating the flow velocity, the flow rate, etc. related to _{(i + l)} and outputting the result to the display means 40 for display.

Next, the overall operation of the arithmetic circuit 8 described above will be described based on the flowchart shown in FIG.

First, in step 200, the counter output C, that is, each of the forward and backward measurement data T _{d (i + l)} and T _{u (i + l)} is input by the measurement data input means 10 shown in FIG. Then, in step 202, the propagation time difference data T _{u (i + l)} is calculated from the input data T _{d (i + l)} and T _{u (i + l),} and the process proceeds to step 204.

In step 204, this propagation time difference ΔT _{u (i + l)} is compared with the propagation time difference ΔT _(i) stored in the storage means 11 (actually RAM8D) by the previous process to obtain the difference, and The difference, that is, “| ΔT _{(i + l)} −ΔT _(i) |” is preset in the keyboard 9 (3rd
(See the figure) and is compared with a reference time value G that is input and set. Then, as described above, when the difference between the old and new propagation time difference data is smaller than the reference time value G, the measured value relating to the latest propagation time difference data is determined to be normal data, and the process proceeds to step 206, while otherwise. Are judged to be abnormal data, and proceed to step 240.

Therefore, even if the input data ΔT _{d (i + l)} and ΔT _{u (i + l)} themselves are significantly different from the previously input data ΔT _{d (i)} and ΔT _{u (i)} , In the example, unless there is a significant change in the difference ΔT _{(i + l)} , all the data is treated as normal data, and the probability of adoption as normal data out of the measured data is significantly increased, improving the measurement accuracy and shortening the measurement time sufficiently. The advantage is that it is possible.

That is, when the input data is determined to be normal data in step 204, the input data T _{d (i + l)} , T
_{u (i + l)} is stored (written in RAM8D) and the process proceeds to step 208. In step 208, the count K of the counter 20A that counts the continuous measurement of abnormal data is set to "K".
= 0 ”, and then in step 210, ΔT _{(i + l)} is stored. Then, in steps 212 to 216, data processing such as calculation of the flow velocity and flow rate based on the data ΔT _{(i + l)} and correction thereof, and subsequently calculation of the total integrated flow rate is performed. To be done. The signal processed in each of these steps is used to drive and display the display means 40 in step 218, which completes one cycle when normal data is obtained. The same process is repeated thereafter.

On the other hand, if the input data is determined to be abnormal data, the input data is not stored and the process proceeds to step 240, where 1 is added to the abnormal data count count K (K = K + 1, initial value K = 0), and thereafter. , Go to step 242.

In step 242, it is determined whether or not the continuous count value of abnormal data, that is, the count number K is larger than the reference value H set by the reference number setting unit 20C (specifically, the keyboard 9). Here, if "K <H", the process returns to step 200, and the data T _{d (i + 2)} and T _{u (i + 2)} relating to the next propagation time are input. On the other hand, if “K> H”, step 24 is performed as it is.
Go to 4. In this step 244, the propagation time difference data ΔT
After writing _{(i + l)} in the storage means 11 (RAM8D), the process proceeds to step 246. In this step 246, the count value K for the abnormal value is set to "K = 0", and in the next step 248, the propagation time difference reference value G in the comparison determination unit 13B (see FIG. 1) is set to G '(where G'> G). ) And return to step 200.
As a result, the next input data T _{d (i + 2)} , T
_A state is set in which _{u (i + 2)} can be processed as normal data due to a change in flow velocity.

〔The invention's effect〕

Since the present invention is configured and functions as described above, according to this, after measuring the propagation time of ultrasonic waves in the forward direction and the reverse direction of the flow of the fluid to be measured, the difference between the propagation times of the ultrasonic waves in the two directions is calculated. Even if the overall sensitivity decreases, the method is used to determine whether or not the measured data is normal data based on a value close to the ultrasonic wave propagation time difference calculated and measured immediately before that. It is possible to calculate the propagation time difference between the forward direction and the backward direction with relatively high accuracy, and it is possible to capture even the measurement data related to the sensitivity decrease as normal data. Since the amount of measurement data greatly increases, it is possible to improve the measurement accuracy, and if the difference between the old and new propagation time difference data is larger than the predetermined reference time difference data, the latest Position the measurement value related to the propagation time difference data as the above data and count the number of consecutive detections of the above data, and if the number of consecutive detections of the above data exceeds a predetermined reference number, then next to the latest above data Since the obtained measured value is adopted as the normal data, even if the flow velocity changes in the tube with many bubbles, for example, the data measured discontinuously and the change in the measured data due to the change in flow velocity can be measured. It is possible to provide an unprecedented excellent method for processing measured values of an ultrasonic flowmeter and its apparatus, which can be discriminated with high accuracy and can be recognized as an overall change in flow velocity and flow rate.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an ultrasonic flowmeter including an embodiment of the present invention, FIG. 2 is an explanatory diagram showing timings of switching signals and transmission / reception signals of FIG. 1, and FIG. First
FIG. 4 is a block diagram showing a hardware configuration of an arithmetic circuit portion of FIG. 4, FIG. 4 is a flow chart showing a procedure of signal processing of the arithmetic circuit portion of FIG. 1, and FIG. 5 (1) (2) (3) (4) are respectively detected. It is explanatory drawing which shows the relationship between the specific example of the various received waveforms and the generation | occurrence | production of the received signal accompanying it. 11 ... storage means, 12 ... propagation time difference calculation section, 13 ... time difference comparison / determination means, 20A ... counter, 20B ... abnormal number comparison section, 20C ... reference number setting section, 30 ... as flow rate calculation section Flow velocity and flow rate calculation part.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshiaki Yamamoto 2-16-46 Minami-Kamata, Ota-ku, Tokyo Tokyo Keiki Co., Ltd. (72) Toshio Komatsu 2--1646 Minami-Kamata, Ota-ku, Tokyo No. Stock Company Tokyo Keiki

Claims (2)

[Claims] 1. The propagation time of ultrasonic waves in the forward direction and the reverse direction of the flow of the fluid to be measured is measured, and then the difference between the propagation times of the ultrasonic waves in the two directions is calculated, and the calculated propagation of the ultrasonic waves is calculated. In a method of processing a measurement value of an ultrasonic flowmeter, which determines a flow rate of a fluid to be measured based on a time difference, a first method of storing a difference in propagation time of ultrasonic waves in a forward direction and a reverse direction of a flow of the fluid to be measured as propagation time difference data. And a second data processing step of comparing the stored propagation time difference data with the latest propagation time difference data stored before that to obtain the difference, and the difference between the old and new propagation time difference data. Is larger than a predetermined reference time difference data, a third data processing step of counting the number of consecutive detections of the abnormal data, and the number of consecutive detections of the abnormal data is a predetermined reference number of times. And a fourth data processing step of adopting, as normal data, a measured value obtained next to the latest abnormal data when the number exceeds the latest abnormal data. 2. A propagation time difference calculation unit for measuring the propagation time of ultrasonic waves in the forward direction and the reverse direction of the flow of the fluid to be measured, and then calculating the difference in the propagation time of the ultrasonic waves in the two directions.
In the measurement value processing device of the ultrasonic flowmeter, which is provided with a flow rate calculation unit that performs a predetermined calculation based on the time difference data obtained by the propagation time difference calculation unit and calculates the flow rate of the fluid to be measured, A storage means for storing the calculation result of the propagation time difference calculation section is provided between the storage section and the flow rate calculation section, and whether the latest time difference data input to this storage means is based on the measured normal data or not. Whether or not based on a preset reference value is determined, and when the data is determined to be normal data, a time difference comparison / determination unit that outputs a calculation command signal to the flow rate calculation unit is provided side by side with the storage unit. A counter for immediately counting the number of consecutive measurements of the abnormal data when the time difference comparison / determination means continuously determines that the latest time difference data is based on the abnormal data, When the number of consecutive abnormalities counted by the counter is larger than a predetermined reference number, the reference value change command for adopting the measured value obtained next to the latest abnormal data as normal data is used for the time difference comparison. A measurement value processing device for an ultrasonic flowmeter, characterized in that an abnormal frequency comparison section for outputting to a determination means is provided together with the time difference comparison and determination means.