JPS62180221A - Method and device for processing measured values of ultrasonic flow meter - Google Patents

Abstract

PURPOSE:To judge a difference between abnormal data and variation in measured value due to variation in flow velocity by employing a measured value obtained after the latest abnormal data as normal data when the frequency of continuous detection of abnormal data exceeds a reference frequency value. CONSTITUTION:Received signals R from ultrasonic transmitter and receivers 3A and 3B are outputted C from a counter circuit 7 through a switching circuit 5 and a receiving circuit 6. A propagation time difference computation part 12 computes the propagation time difference between new and old data with the output C and the difference is stored 11. Then, a time difference comparing and deciding means 13 employs the latest time difference data as normal data when the difference is smaller than a reference value, and handles it as abnor mal measurement data and also counts the frequency of continuous detection of abnormal data by a counter 20A when the difference is larger than the refer ence value. Then when the frequency of abnormality detection exceeds the reference value, the measured value obtained after the latest data abnormal data is employed as normal data. Consequently, the difference between abnormal data and variation in measured value with a flow rate is judged.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for processing measured values of an ultrasonic flowmeter and an apparatus therefor, and in particular, an ultrasonic flowmeter suitable for flow rate measurement of fluids that are easily mixed with air bubbles and the like. The present invention relates to a method for processing measured values of a meter and an apparatus thereof.

[Conventional technology]

For example, as a method for processing measured values of ultrasonic flow needles that has been commonly used, for example, Japanese Patent Publication No. 59-14173
There is something related to the publication number. This conventional example first detects the propagation time of each ultrasonic wave in the forward and reverse directions following the fluid flow, and then sets a reference level for the lamp voltage formed in response to the level of this detection signal. For each reference level, an upper limit and a lower limit are set, and data exceeding these limits is determined to be abnormal data. When specifically employing the measured values, the method employs both the measured values only when the received signals in both the forward and reverse directions are normal.

On the other hand, although it is not specifically disclosed in the above-mentioned 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 FIG. 5(1) (31( 4
There are various changes as shown in A and B of 1.

For this reason, determining the arrival time of the ultrasonic wave based on which part of the wave is an important issue when accurately measuring flow rate.

What has been commonly adopted in the past is to first determine the reception reference level SL, and then define the point at which the first wave that reaches this reception reference level S intersects its central time axis (zero level) as a specific point (zero cross point). There is a method in which this specific point is used as a reference measurement point on the receiving side to determine when the received signal arrives.

To explain this in more detail with reference to Fig. 5 mentioned above, in Fig. 5, A indicates the received ultrasonic signal (solid line) in the forward direction along the flow of the fluid to be measured, and B indicates the received signal in the reverse direction against the flow. The first peak of the received waveform is the first wave (■), the trough that follows it is the second wave (■), and the second peak is the third wave (■).

The trough that follows this is called the 4th wave ■, and the peak of Sanyomame is called the 5th wave ■. The first time these waveforms intersect with the reception reference level St is, for example, the third wave in the case of FIG. The intersection point (zero crossing point) is identified.

That is, in the case of FIG. 5 (1), both received signals A and B are
The wave exceeds the reception reference level SL. Also in the same figure (2)
In the case of , the received signal A is in a state where the reception sensitivity is deteriorated overall due to the presence of air bubbles in the fluid.

In both cases B, the fifth wave exceeds the reception reference level SL, and the situation is different from that shown in (1) of the same figure. Furthermore, Figure 5 (3
), the received signal A in the forward direction is the third wave.

Furthermore, the fifth wave of the received signal B in the opposite direction exceeds the reception reference level SL, which is a situation markedly different from the above two examples, and is an abnormal phenomenon that often occurs during actual measurement.

[Problem that the invention seeks to solve]

Among the received signals shown in FIG. 5 described above, FIG. 5(1) is normal. The problem shown in FIG. 2 (2) occurs depending on the influence of bubbles flowing together with the fluid to be measured, voltage fluctuations in the power supply, malfunctions in the transmitting system or receiving system of the device, and the like. Moreover, the signal shown in FIG. 3 (3) is a clear abnormal signal caused by an abnormality in the fluid to be measured (mostly due to the presence of air bubbles).

In response to such various received signals, conventional devices specifically extract the received signals of each ultrasonic wave in the forward and reverse directions of the fluid to be measured, as shown in the aforementioned Japanese Patent Publication No. 59-14173. The presence or absence of an abnormality is checked, and unless both are normal at the same time, all received signals are judged to be abnormal and are discarded. Therefore, in the above employee example, the arrival time of the received signal Tu(i++1) in the opposite direction among the received waveforms in FIG. i-
:nJ, so if the value shown in FIG. 5 (1) is taken as a normal value, all other values are judged to be abnormal values.

For this reason, in the conventional example described above, the probability of adopting a normal value is poor, and in some cases, the probability of adopting a normal value is only one out of three measurements, or less than that, which not only wastes a lot of measurement, but also reduces the reliability of the measurement results. There is an inconvenience that the
In order to compensate for this, it is necessary to set a long measurement time and detect many normal values, which has the disadvantage of poor response to changes in transmission speed.

[Purpose of the invention]

The present invention improves the disadvantages of the conventional example, and in particular, it is possible to judge the difference between abnormal data and changes in measured values due to changes in flow velocity, and to sufficiently respond to rapid changes in flow velocity. The object of the present invention is to provide a method for processing measured values of an ultrasonic flowmeter and an apparatus therefor.

[Means for solving problems]

Therefore, in the present invention, first, the propagation time difference of these ultrasonic waves is calculated based on the propagation time of the ultrasonic waves in the forward direction and the reverse direction of the flow of the fluid to be measured, and this calculated propagation time difference of the ultrasonic waves is calculated. In the ultrasonic flow rate measuring method for determining the flow rate of the fluid to be measured based on the flow rate of the fluid to be measured, the ultrasonic propagation time difference data between the forward direction and the reverse direction of the flow of the fluid to be measured is stored, and the stored time difference data is The difference is determined by comparing it with the latest propagation time difference data stored previously. Next, if the difference between the new and old propagation time difference data is larger than a predetermined reference value, the measurement data related to the latest propagation time difference data is regarded as abnormal data and the number of consecutive detections thereof is counted. Then, when the number of consecutive detections of this abnormal data exceeds a predetermined standard number of times, a method is adopted in which the measurement value obtained next to the latest abnormal data is adopted as normal data, thereby achieving the above purpose. This is what we are trying to achieve.

[Embodiments of the 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 direction of arrow 2 within the tube l. The pipe body 1 contains a fluid to be measured 2.
It is divided into upstream and downstream parts, and is equipped with ultrasonic transducers 3A and 3B on the upper and lower sides, respectively, as shown in the figure, at a constant interval. This ultrasonic transducer 3A.

3B, a transmission signal T is alternately sent from the transmission circuit 4 as the excitation signal every repetition period S.

That is, the transmitting circuit 4 has a function of outputting an excitation signal T of a predetermined frequency and a switching signal S for the switching circuit 5 to the switching circuit 5. The switching circuit 5 switches at the timing of a predetermined repetition period S shown in FIG. 2, and when one ultrasonic transducer 3A is in a transmitting state, the other ultrasonic transducer 3B is in a receiving state. It is now set. Tube 1
The diagonal dotted line P inside indicates the propagation path of the ultrasonic waves.

The reception signal R sent from the ultrasonic transducer 3A or 3B is sent to the reception circuit 6 via the switching circuit 5. This receiving circuit 6 manually amplifies the received signal R, and also includes a built-in zero-crossing pulse generator (not shown).
pulse signals R/ and R// are generated and output (see FIGS. 2 and 5 (2)). This pulse signal R'
, R'' are 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, this counter circuit 7
Now, the transmission signal T and the output signal R' of the receiving circuit 6.

First, a clock pulse C' is formed by the gate signal formed by RII, and the count data, which is the count value of this clock pulse C', is sent to the arithmetic circuit 8 as the counter output C.
It is now output to .

FIG. 2 shows each of these signals and their timing chart.

Here, the counter output C is a signal including information regarding the propagation time of each ultrasonic wave in the forward direction and in the reverse direction of the fluid to be measured. The arithmetic circuit 8 into which this information is input performs various calculations such as the flow rate and the integrated flow rate in addition to calculating the flow rate, and then outputs this to the display means 40 so that it can be displayed. .

Specifically, as shown in FIG. 3, the aforementioned arithmetic circuit 8 includes an input/output interface circuit (1/D IFC) 8A,
Central processing unit (CPU) 8 B, read-only memory (ROM) in which programs are written 8 G,
A writeable and readable memory (RAM) that stores data and other command signals, etc. 8 D and a clock oscillator (OSC) that serves as a reference for calculations and outputs lock pulses From a microcomputer whose main parts include 8 E, etc. Become. The arithmetic circuit 8 is provided with the functions shown in FIG. 1, and inputs the output signal C from the counter circuit 7, while inputting setting values and the like necessary for starting the calculation from the keyboard 9, as shown in FIG. A predetermined calculation is performed according to the flowchart shown in FIG.

Next, the configuration and operation of the arithmetic circuit 8 as a specific technical concept will be explained.

In FIG. 1, the counter output C input to the measurement data input means 10 is a signal TdB+B representing the forward ultrasound propagation time of the fluid to be measured and a signal Tt+(,) representing the reverse ultrasound propagation time. It has both data of 1. Here, ri=o, 1°2.3.
, .

This counter output C, that is, Tdo++, and Tu(i
ll) is inputted and stored in the storage means 11 for each forward and backward repetition period. This storage means 11 is also provided with a propagation time difference calculating section 12 . This propagation time calculation unit 12 is configured to read out data Td (i. 1. and Tu (fall) and calculate their propagation time difference data ΔT□1) which are temporarily stored in the storage means 11. Propagation time difference data ΔT (i.1. is T4B*
When n and T u (i.1.) are normal data, they are formally stored in the storage means 11. 13, it is determined whether the data is normal or not. Here, the propagation time difference data ΔT determined to be normal data
(Fall is the next propagation time difference data 8T (□42)
Or, it is formally stored in the storage means 11 until ΔT(i□) is determined to be normal data.

The time difference comparison and determination means 13 includes a time difference comparison calculation unit 13A, a reference setting unit 13B that outputs a reference value G of the propagation time difference data ΔT, which is an output of the time difference comparison calculation unit 13A, and a reference value G. Propagation time difference data ΔT1. . 1
．． and a comparison/judgment section 13C that compares the two and outputs a predetermined control signal, which will be described later.

To explain this in more detail, first, the time difference comparison calculation unit 13A calculates the propagation time difference data ΔT to be stored in the storage means 11.
, □. 2. is the normal data ΔT31. which was previously stored in the storage means 11. Compare to see if they are approximately equal.

For this reason, the time difference comparison calculation section 13A stores the storage means 1.
1, the propagation time difference data ΔTH*u and the previously stored propagation time difference data ΔT (il) are read out and compared.
Output to.

The comparison/determination unit 13C compares the calculation result “1ΔT(+++, −ΔTt=)lJ” in the time difference comparison calculation unit 13A with the reference value G input from the reference value setting unit 13B, and calculates 1ΔT(i
. 1. -When ΔT+t+l≧G, it outputs a write stop signal to the storage means 11 to stop writing ΔT+t+++ as abnormal data, and also outputs a step signal to step an abnormal value counter 20A, which will be described later. ing. Further, when the calculation result in the time difference comparison calculation unit 11A is smaller than the reference value G, that is, when 1ΔT+i+n−ΔT (++l<G), the comparison determination unit 13C writes ΔT, i, . . . as normal data. It has a function of outputting a storage command signal for command to the storage means 11, and at the same time outputting a clear signal to the abnormal value counter 2OA and a calculation No. 11 to the flow rate calculation section 30, respectively.

Furthermore, the comparison/judgment section 13G has a function of changing the reference value G to G' or G II based on an external command (where c<c/<cII).

The comparison and determination section 13C of the time difference comparison and determination section 13 is provided with a flow velocity change determination section 20. This flow velocity determination means 20 includes a counter 2 that counts the number of consecutive detections of abnormal values.
0A, and when the counted value of this counter 20A exceeds the reference number of times H, the measured value obtained after the latest abnormal data is stored as normal data due to the change in flow velocity.
A reference value change command for changing the reference value G to G' or G II is output to the comparison/judgment section 13C.

It is composed of an abnormal number comparison section 20B that outputs a clear signal to the counter 20A, and a reference number setting section 20C that sends a signal related to the reference number H to the abnormal number comparison section 20B.

The flow rate calculation section 30 operates when a calculation command signal is output from the time difference comparison and determination means 13, and stores the storage means 1.
A predetermined calculation is immediately started based on the propagation time difference data sent from 1, and the propagation time difference data ΔT (1
+11, etc., and has a function of outputting the results to the display means 40 for display.

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

First, in step 200, the measurement data input means 10 shown in FIG. 1 outputs the counter output C, that is, each measurement data T, . ,,, Tu(il+1
Then, in step 202, input data Ta+=
++++ Tu(il+1 to propagation time difference ΔT(il1
1 and proceeds to step 204.

In step 204, this propagation time difference ΔTLi. 1) and the previous processing, it is stored in the storage means 11 (actually, RAM8D
) and the propagation time difference ΔT(il) stored in
1J is compared with a reference time value G that is input and set in advance from the keyboard 9 (see FIG. 3). As described above, if the difference between the new and old propagation time difference data is smaller than the reference value G, the measured value related to the latest propagation time difference data is determined to be normal data and the process proceeds to step 206; Determine all data as abnormal and step 2
Proceed to 40.

For this reason, the input data ΔTd(i), and ΔTu(
1. The first item itself is the data ΔTd (
i) and ΔTu (il), in this example, unless there is a significant change in the difference ΔTtt*+y, all are treated as normal data, and the probability of adoption as normal data among the measured data is significantly increased. This has the advantage that measurement accuracy can be improved and measurement time can be sufficiently shortened.

That is, when the input data is determined to be normal data at step 204, the input data is determined to be normal data at step 206.
I)+Tu(il+1 is memorized (written to RAM8D) and the process proceeds to step 208. In this step 208,
As mentioned above, the count K of the counter 2OA that counts the number of consecutive measurements of abnormal data is set to rK=OJ, and then ΔT(...I) is stored in step 210. Then, in steps 212 to 216, the data is Δ
The flow rate and flow rate are calculated and corrected based on TB+n, and then data processing such as calculating the total integrated flow rate is performed. The signals processed in each of these steps are used to drive and display the display means 40 in step 218, thereby completing one cycle when the data is determined to be normal. The same process is repeated thereafter.

On the other hand, if the input date and evening are 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 K (K=+1
．． If the initial value is set to 0), then the process proceeds to step 242.

In this step 242, it is determined whether or not the continuous count value of the abnormal data, that is, the count number K is larger than the reference value H set by the reference number setting section 20C (specifically, the keyboard 9). Here, if rK<HJ, step 2
Returns to 00, and data Td, , related to the next propagation time. l)
+ Tu(i.2. is input. On the other hand, if rK>HJ, proceed directly to step 244. This step 24
In step 4, the propagation time difference data ΔTB+u is written in the storage means 11 (RAM8D), and then the process proceeds to step 246. In this step 246, the count number K for abnormal values is
is set as rK=OJ, and in the next step 248, the ratio soft decision unit 1
The propagation time difference reference value G within 3B (see Figure 1) is
' (where G'>G) is set, and the process returns to step 200. As a result, the next input data T a (=
A state is set in which +21 l T u (r. 7.) can be processed as normal data accompanying a change in flow velocity.

〔Effect of the invention〕

As described above, according to the present invention, 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 is determined, the propagation time difference data is stored, and the stored time difference data is used before that time difference. The difference is determined by comparing it with the latest stored propagation time difference data, and if the difference between the old and new propagation time difference data is larger than a predetermined reference value, the measured data related to this latest propagation time difference data is is treated as abnormal data, and the number of consecutive detections of the abnormal data is counted, and when the number of consecutive detections of this abnormal data exceeds a predetermined standard number of times, the measured value obtained next to the latest abnormal data is used as the flow velocity. Since we adopted the method of adopting the normal data associated with changes and were configured as described above, for example, even if the flow velocity changes in a pipe with many bubbles, it is possible to distinguish between clearly abnormal data measured discontinuously and with flow velocity changes. It is possible to provide a method and an apparatus for processing measured values of an ultrasonic flowmeter that are unprecedented and superior in that they can identify changes in measurement data with high precision and calculate changes in flow velocity and flow rate.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an ultrasonic flowmeter including an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the timing of switching signals and transmission/reception signals, etc. in FIG. 1, and FIG. 1st
4 is a block diagram showing the hardware configuration of the arithmetic circuit section of FIG. 4 is a flowchart showing the signal processing procedure of the arithmetic circuit section of FIG. It is an explanatory diagram showing specific examples of various received waveforms and their relationship with the generation of received signals. 11... Storage means, 12... Propagation time difference calculation unit, 13... ...Time difference comparison and determination means, 20
A...Counter, 20B...Abnormal number comparison section, 20C..., Standard number setting section, 30.
...Flow rate calculation section as a flow rate calculation section. Patent applicant: Tokyo Co., Ltd. Meter Figure 1 Figure 2 Figure 4

Claims (2)

[Claims] (1) Calculate the propagation time difference of each ultrasonic wave based on the propagation time of the ultrasonic wave in the forward direction and reverse direction of the flow of the fluid to be measured, and based on the calculated propagation time difference of the ultrasonic wave. In the measurement value processing method of an ultrasonic flowmeter that determines the flow rate of the fluid to be measured, data on the difference in propagation time of ultrasound between the forward direction and the reverse direction of the flow of the fluid to be measured is stored, and then the stored Compare the time difference data with previously stored propagation time difference data to find the difference, and if the difference between the new and old propagation time difference data is greater than a predetermined reference value, count the number of consecutive detections of the abnormal data. and, when the number of consecutive detections of this abnormal data exceeds a predetermined standard number of times, the measurement value obtained next to the latest abnormal data is adopted as normal data. Value processing method. (2) A propagation time difference calculation unit that calculates the propagation time difference based on the propagation times of the ultrasonic waves related to the forward and reverse flows of the fluid to be measured and input, and the propagation time difference calculation unit In a measurement value processing device for an ultrasonic flowmeter, comprising a flow rate calculation unit that performs a predetermined calculation based on obtained time difference data to calculate the flow rate of the measured fluid, the propagation time difference calculation unit and the flow rate calculation unit In between, a storage means for storing the calculation result of the propagation time difference calculating section, and determining whether or not the latest time difference data inputted to this storage means is normal data based on a preset reference value, and a time difference comparison and determination means that immediately outputs a calculation command signal to the flow rate calculation section when the measured value is determined to be normal data, and when the time difference comparison and determination means continuously determines that the measured value is abnormal data. A counter that counts the number of consecutive measurements of abnormal data, and if the number of consecutive abnormalities counted by this counter is greater than a predetermined standard number of times, the measurement value obtained next to the most recent abnormal data is regarded as normal data. A measured value processing device for an ultrasonic flowmeter, comprising: an abnormality frequency comparison section that outputs a reference value change command for adoption to the time difference comparison and determination means.