KR101484421B1 - Ultrasonic flow measurement system chordal path compensation method - Google Patents

Abstract

The present invention restrains lowering of flow rate calculated even when a failure occurs at one among a plurality of chordal paths and includes a compensation table having coefficients for weighting flow velocities in the chordal paths M, respectively; a normal time compensation table used when all the chordal paths M are normal; a memory circuit memorizing various kinds of compensation tables including an abnormal time compensation table different from the normal compensation table; a calculation circuit calculating an average flow velocity as an average of plural compensation values by multiplying the flow velocity of each chordal path M with the coefficient of the compensation table; and a determination circuit determining that the chordal path M is abnormal when measurement can not be performed in the chordal path M and simultaneously determining that the chordal path M is abnormal when the flow velocity of the chordal path M is deviated from a set range. The calculation circuit, if the determination circuit determines that the chordal path M is abnormal, excepts the flow velocity of the abnormal chordal path M from the calculation and calculates the flow rate according to an average flow velocity calculated by using the flow velocities of the remaining chordal paths M and the abnormal time compensation table.

Description

ULTRASONIC FLOW MEASUREMENT SYSTEM CHORDAL PATH COMPENSATION METHOD [0002]

The present invention relates to an ultrasonic flow meter, and more particularly, to a flow meter using ultrasonic waves and a flow rate calculation method for calculating a flow rate according to a plurality of measured values.

The flowmeter has an ultrasonic flowmeter that measures the flow rate using ultrasonic waves. The ultrasonic flowmeter has a plurality of lateral lines for measuring the flow rate of the fluid flowing in the flow channel, and is known as a so-called multi-side linear ultrasonic flowmeter by calculating the flow rate using an average of the flow velocities measured by a plurality of lateral lines Reference 1)

In the multi-side linear ultrasonic flowmeter related to the present invention, a plurality of side lines are disposed on the same cross section of the flow paths with spacing. One side line has a pair of ultrasonic transducers for receiving and receiving ultrasonic waves and one ultrasonic wave transducer is disposed on the upstream side of the flow path and the other side of the ultrasonic wave transducer is disposed on the downstream side of the flow path. A pair of ultrasonic wave transducers are disposed at positions opposed to each other with the oil passage therebetween. In one lateral line of the ultrasonic flowmeter, the flow velocity is calculated through computation according to the difference of propagation time of the ultrasonic waves detected by each ultrasonic wave transceiver.

In multi-sided linear ultrasonic flowmeters, considering the flow velocity distribution, which is generally high at the center of the pipe and the flow velocity near the inner wall of the pipe, and the imbalance of the measured flow velocity, The flow rate is calculated using the average flow rate calculated by giving relative weights to the flow velocities of the different lateral lines of each lateral line.

Specifically, in the ultrasonic wave flowmeter of a multi-line linear type, a predetermined coefficient predetermined for each position of the sidewall is multiplied by each flow velocity to calculate a correction value, and a flow rate is calculated using the average of a plurality of correction values, that is, a weighted average using an average flow rate. That is, in the ultrasonic wave flowmeter of the multi-line linear type, the flow rate is calculated by using the correction table having the weight coefficient corresponding to each side line.

In the ultrasonic wave flowmeter of the multi-line linear type described above, it is judged whether or not the flow velocity in each of the side lines is within a predetermined range, and it is judged whether or not the flow rate of the side lines is abnormal. If it is determined that the flow velocity of the sidewall is out of the predetermined range and is abnormal, the flow rate of the failed sidewall changes to a median value within a predetermined range and is used for calculation like the flow rate of other normal sideways. That is, even if the sidewall is broken, the flow rate of the sidewall is changed to the designated value and is used for the calculation, and the flow rate is calculated by multiplying the predetermined value by the weight coefficient as in the case where the sideline is normal and using the average flow rate as the weighted average described above .

Since such an operation is performed, there is a problem that the accuracy of the flow rate (hereinafter referred to as the degree of flow rate) obtained by calculation when the sideline fails in the ultrasonic wave flowmeter of the multi-line linear type related to the present invention is reduced.

Further, when a plurality of side lines are broken, since the plurality of side line flow rates are changed to predetermined values and used for the calculation, there is a problem that the degree of the flow rate required by the calculation remarkably decreases.

Japanese Patent Application Laid-Open No. 2006-317187

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a flow meter and a flow rate calculation method capable of suppressing a decrease in the calculated flow rate even if one of the plurality of side lines fails.

In order to achieve the above object, a flow meter capable of responding to a failure of a sideline according to the present invention is provided with a sideline having a pair of ultrasonic transducers for measuring the flow rate of fluid in the flow path, A plurality of side lines arranged,

A first arithmetic processing unit for calculating a flow velocity of each of the lateral lines in accordance with the measured value of the ultrasonic transducer,

A judgment processing section for judging that the lateral line is abnormal when the lateral line can not be measured and for judging that the lateral line is abnormal when the lateral line flow rate is out of the predetermined range,

There are a correction table having coefficients for weighting each flow velocity of each of the lateral lines to correct the flow velocity of each of the lateral lines, a normal-time correction table used when all the lateral lines are normal, A storage unit in which a correction table of a kind is stored,

And a second arithmetic processing section for calculating the average flow velocity as an average of a plurality of correction values by multiplying the flow velocity of each of the lateral lines by the coefficient of the correction table.

Further, when it is determined by the judgment processing unit that the sideline is abnormal, the second calculation processing unit excludes the flow velocity of the abnormal sideline from the calculation, and calculates the average calculated using the flow rate of the remaining remaining sideline and the abnormal- And the flow rate is calculated according to the flow velocity.

A flow rate calculation method according to the present invention is a flow rate calculation method for calculating a flow rate of a flow path by using a plurality of side lines having a pair of ultrasonic wave transmission and reception devices installed in a flow path,

A first calculation step of calculating a flow velocity of a sideline line according to a measured value with an ultrasonic wave transmitter and receiver,

A determination step of determining that the sideline is abnormal when the measurement can not be performed on the sideline and determining that the sideline is abnormal when the flow velocity of the sideline is out of a predetermined range,

There is a correction table having a coefficient for weighting each flow velocity of each of the sideways to correct the flow velocity of each sidewall, a normal-use correction table used when all the sideways are normal, and a correction table for abnormal use unlike the normal- And a second calculation step of calculating an average flow velocity as an average of a plurality of correction values by multiplying the flow velocity of each of the plurality of sorts by a coefficient of the correction table.

In the second computation step, when it is determined that one of the plurality of lines is abnormal, the flow rate is calculated in accordance with the normal flow velocity except the flow velocity of the strange side line and the average flow velocity calculated using the abnormality correction table It is another feature.

According to the present invention, it is possible to suppress the degree of the calculated flow rate from being lowered even when an abnormality occurs in one of the plurality of sidelines.

1 is a schematic diagram showing an ultrasonic flowmeter of an embodiment of the present invention.
2A and 2B are schematic diagrams for explaining a plurality of sidelines provided in the ultrasonic flowmeter of the embodiment of the present invention.
Fig. 3 is a schematic diagram for explaining the principle of calculating the flow velocity with respect to the sideline provided in the ultrasonic flowmeter of the embodiment of the present invention. Fig.
4 is a flowchart for explaining a process of calculating a flow rate using a plurality of side lines in the ultrasonic flowmeter of the embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

1 is a schematic view of an ultrasonic flowmeter of an embodiment of the present invention. Figs. 2A and 2B are schematic diagrams for explaining a plurality of side lines provided in the ultrasonic flowmeter of the embodiment of the present invention. Fig. The ultrasonic flowmeter of the embodiment is used, for example, as a liquid to calculate the flow rate of the cooling liquid flowing through the flow path of the cooling circuit, but can of course be used for calculating the flow rate of the gas.

As shown in Fig. 1, the ultrasonic flowmeter 1 of the embodiment has a pair of ultrasonic transducers 5 for measuring the flow velocity of liquid flowing in the circular tube 3, and a first side line M1 And an arithmetic circuit 9 as a first arithmetic processing section for calculating the flow velocity of each of the first lateral line M1 to the eighth lateral line M8 in accordance with the measured value at the ultrasonic wave transmitting and receiving device 5. [

Further, the ultrasonic flowmeter 1 has a coefficient (hereinafter referred to as a weight coefficient) which is a weighting factor for the flow velocity of each of the first side line M1 to the eighth side line M8 to correct the flow velocity of each of the first side line M1 to the eighth side line M8, a and the correction table having, equipped with all survey line M memory circuit 7 as a storage unit is storing several types of the correction table containing the correction table of the above trial, unlike normal trial correction table, normal trial correction table to be used when the normal.

Further, the ultrasonic flowmeter 1 includes an arithmetic circuit 9 as a second arithmetic processing unit for calculating an average flow velocity as an average of a plurality of correction values obtained by multiplying the flow velocities of the first to fifth eccentric lines M8 and M8 by a weighting coefficient possessed by the correction table, If it is not possible to measure at the first side line M1 to the eighth side line M8, it is determined that the side line M is abnormal, and at the same time, one of the measured values of the first side line M1 to the eighth side line M8 is shifted to the side lines M1 to M8 And a judgment circuit 8 as a judgment processing section for judging that the side line M is abnormal when the predetermined range is out of the predetermined range.

When the determination circuit 8 determines that the side line M is abnormal, the calculation circuit 9 calculates the flow rate in accordance with the average flow rate calculated using the flow rate of the remaining remaining side line M and the abnormality correction table except for the flow rate of the abnormal side line M .

Although not shown, the ultrasonic flowmeter 1 includes a processing circuit for determining the timing of sending and receiving the ultrasonic waves to avoid the measurement of each of the side lines M1 to M8 interfering with the measurement of the other side line M, And a temporary storage circuit for temporarily storing measured values measured at each of the side lines.

The ultrasonic transducer 5 is composed of a piezoelectric transducer having an ultrasonic transmitter and a ultrasonic wave receiver. As shown in FIGS. 2A and 2B, the ultrasonic wave transmitter / receiver 5 that emits ultrasonic waves at one side line M and receives ultrasonic waves is disposed at a position opposed to each other with the flow path 4 therebetween.

Further, one ultrasonic wave transmitting / receiving device 5 is disposed on the upstream side of the flow path 4 with respect to one side line, and another ultrasonic wave transmitting / receiving device 5 is disposed on the downstream side of the flow path 4.

The first to fourth side lines M1 to M4 are arranged in parallel on the same cross section of the flow path 4 with an interval therebetween. The fifth to eighth lateral lines M5 to M8 are arranged parallel to each other on the same cross section of the flow channel 4, unlike the cross section on which the first to fourth lateral lines M1 to M4 are arranged, and the first to fourth lateral lines M1 To M4, respectively.

The memory circuit 7 is constituted by, for example, a memory semiconductor, and is electrically connected to the arithmetic circuit 9 and the decision circuit 8. [ The calculating circuit 9 and the judging circuit 8 are constituted by, for example, a CPU, and are electrically connected to the respective ultrasonic wave transmitting and receiving devices 5 constituting the first to eighth lateral lines M1 to M8. In the present embodiment, the arithmetic circuit 9 and the determination circuit 8 are configured to be independent from each other, but they may be configured by one processing circuit. A judgment circuit for judging that the side line M is abnormal when it can not be measured by the side line M and a judgment circuit for judging that the side line is abnormal when the measured value is out of the predetermined range on the side line M may be separately provided.

A weight coefficient relative to the flow velocity of the plurality of side lines M is set to the flow velocity at one of the side lines M. This weighting coefficient varies depending on the position of the side line M of the flow path 4 and is previously calculated and set according to the properties of the fluid such as the kind of fluid, temperature, pressure, impurity concentration, .

Further, the correction table stored in the memory circuit 7 has a plurality of weighting coefficients corresponding to each of the plurality of side lines M.

In addition, the arithmetic circuit 9 selects a desired correction table among correction tables for various types of abnormal application according to the line M determined to be abnormal, and performs calculation using the selected correction table. For example, a correction table for use in the case where the first lateral line M1 is broken and a correction table for use in the case where the second lateral line M2 fails. Here, the principle and calculation for obtaining the flow rate of the fluid flowing through the flow path 4 from one side line M equipped with the ultrasonic flowmeter 1 will be described.

The lateral line M of the ultrasonic flowmeter 1 measures the propagation speed of the ultrasonic wave by detecting the propagation time of the ultrasonic wave by propagating the ultrasonic wave to the fluid of the flow path 4. At this time, the propagation speed of the ultrasonic wave propagating in the fluid varies with the flow rate of the fluid.

If the velocity of the ultrasonic wave is c (m / sec) and the velocity of the fluid is V (m / sec), the propagation velocity observed when the ultrasonic wave propagates from the upstream to the downstream is c + V, The propagation velocity observed when propagating is cV. When the direction of propagation of the ultrasonic wave with respect to the flow direction of the fluid forms the angle θ, the propagation velocity becomes c ± V cos θ. When the fluid has a flow velocity distribution in the flow path 4, the flow velocity V of the fluid is an average flow velocity on the propagation path of the ultrasonic waves.

In order to calculate the flow rate (m3 / sec) of the flow path 4, the flow rate is calculated by multiplying the cross-sectional average flow velocity of the flow path 4 by the cross-sectional mean velocity (m / sec)

Fig. 3 is a schematic diagram for explaining an operation to be executed by using a pair (pair) of ultrasonic transducers 5 on one line M; Fig. It is assumed that a flow such as a flow velocity distribution A is formed in the flow path 4 in the circular tube 3 as shown in Fig.

As shown in Fig. 3, the ultrasonic wave transmitting / receiving device 5a is disposed upstream of the flow path 4, and the ultrasonic wave transmitting / receiving device 5b is disposed downstream of the flow path 4. Let L be the distance (propagation path length) of the ultrasonic waves propagated by the two ultrasonic transducers 5a and 5b and ultrasonic waves, t0 be the propagation time when ultrasonic waves are transmitted to the metal portions of the ultrasonic transducers 5a and 5b mounted on the circular tube 3, The propagation time at which ultrasonic waves are transmitted from the ultrasonic transducer 5a to the downstream ultrasonic transducer 5b is t1 and the propagation time at which ultrasonic waves are transmitted from the ultrasonic transducer 5b to the upstream ultrasonic transducer 5a is t2.

The ultrasonic wave transmitted from the upstream ultrasonic transducer 5a is received by the downstream ultrasonic transducer 5b while moving in the direction of the fluid flow. On the other hand, the ultrasonic wave transmitted from the downstream ultrasonic transducer 5b is received by the upstream ultrasonic transducer 5a while moving in the direction opposite to the flow direction of the fluid.

The propagation time t0 in the metal is subtracted from the propagation time between the ultrasonic wave transceiver 5a and the ultrasonic wave transceiver 5b to calculate the propagation time t1, t2 in the fluid.

The propagation speed of the ultrasonic wave is c + Vcos &thetas; when the ultrasonic wave is transmitted from the upstream ultrasonic transducer 5a to the downstream ultrasonic transducer 5b with respect to the flow of the fluid, and the ultrasonic wave transducer 5b upstream of the ultrasonic transducer 5b, The propagation speed of the ultrasonic wave is c-V cos?. Here, let V be the velocity of the fluid, and c be the ultrasonic velocity in the stopping fluid of the same fluid, the same temperature, and the same pressure.

At this time, c + Vcos? = L / t1 and c-Vcos? = L / t2,

를 이용해 구할 수 있다. 또는 정지 유체 중의 초음파 속도 c로 전파 시간 차이

를 이용해 구할 수 있다. 전파 시간 차이

는 초음파 송수파기 5a로 계측한 신호와 초음파 송수파기 5b에서 계측된 신호 등을 비교해 위상차를 구하는 수단을 이용해 측정 정밀도를 높임으로써, 계측 정도의 향상을 도모할 수 있다.As described above, since the average flow velocity of the fluid in the flow path 4 is the propagation time t1, t2 of the ultrasonic wave and the propagation time difference

. Or propagation time difference at ultrasonic velocity c in the stationary fluid

. Propagation time difference

The measurement accuracy can be improved by increasing the measurement accuracy by comparing the signal measured by the ultrasonic transducer 5a with the signal measured by the ultrasonic transducer 5b and obtaining the phase difference.

The ultrasonic flowmeter 1 of the embodiment has the first to fourth side lines M1 to M4 arranged on the same section of the circular tube 3 and the eight side lines M of the fifth to eighth side lines M5 to M8 arranged on the same section Therefore, eight flow velocities are calculated from the measured values on the eight side lines M, respectively.

The processing in the case where an abnormality occurs in the side line M in the ultrasonic flowmeter 1 configured as described above will be described with reference to Fig.

)에 따라 연산 회로 9가 유속을 각각 산출한다. 연산 회로 9는 산출한 8개의 측선 M의 유속을 판정 회로 8로 보낸다.First, the ultrasonic flowmeter 1 measures the measured values (propagation time t1, t2, propagation time difference

The calculation circuit 9 calculates the flow velocity. The calculation circuit 9 sends the calculated flow velocity of the eight lines M to the decision circuit 8.

At this time, when the ultrasonic wave transmitter / receiver 5 can not receive the ultrasonic wave and the arithmetic circuit 9 can not calculate the flow velocity, the judgment circuit 8 can not measure the side line M and judges that the side line M is abnormal. In this way, the judging circuit 8 judges whether or not it has been possible to measure all of the eight side lines M in accordance with the signal received from the calculating circuit 9 as in step S1. If one of the eight side lines M can not be measured, the process proceeds to step S4 described later. If all of the eight lines M can be measured, the process proceeds to step S2, and the determination circuit 8 determines whether or not the flow rates of the eight lines M are normal, that is, whether they are within a predetermined range.

If all of the flow rates of the eight side lines M are within the predetermined range, the determination circuit 8 determines that all of the eight side lines M have been normally measured.

In addition, after the signal is directly sent to the determination circuit 8 on each of the side lines M and the priority determination circuit 8 determines whether or not the measurement on each of the side lines M is possible, the calculation circuit 9 calculates the flow rate according to the measured value of the measured side line M .

When all the lateral lines M are normal, the correction value is calculated using the weight coefficients of the normal time correction table using the flow rates of the eight line M as in step 3, and the average flow rate is calculated as an average of a plurality of correction values. The calculating circuit 9 calculates the flow rate of the flow path 4 and terminates the flow rate measurement by using the average flow rate calculated in this way and the value of the cross-sectional area of the flow path 4.

Next, when the measurement on one of the side lines M fails and the flow rate of one side line M deviates from the predetermined range, the determination circuit 8 determines that an abnormality has occurred on the side line M (steps S1 and S2). In this embodiment, as an example, the determination circuit 8 determines whether or not two or more side lines M whose flow rate is abnormal (at step S4) is greater than or equal to 2. If two or more side lines M are determined to be abnormal, Lt; / RTI > Of course, it is possible to prepare an abnormal-timing correction table corresponding to the case where two side lines M are simultaneously abnormal. In this case, however, the accuracy (degree) of the measured flow rate is assumed to be lowered.

If it is determined in step S4 that one of the side lines M is abnormal, the process proceeds to step S5. The flow velocity of the line M determined to have an abnormality as in step S5 is not used for calculation of the average flow velocity but is excluded and the average flow velocity is calculated using the flow velocity only in the remaining seven normal line M's.

At this time, the judging circuit 8 judges whether or not the calculation is performed in the various types of correction tables by using the flow rates of seven normal lines M, except for the n-th (n = 1 to 8) line M which is one of the first to eighth lines M1 to M8. And selects a desired abnormality correction table according to the side line M to be excluded from the line. Then, the correction value is calculated by using the weight coefficient of the correction table for abnormal application by using the flow rate of the seven side lines M, and the average flow rate is calculated. The calculation circuit 9 calculates the flow rate of the flow path 4 by using the average flow velocity thus calculated and the cross-sectional area of the flow path 4. As described above, the ultrasonic flowmeter 1 can correspond to the flow channel 4 having the flow velocity distribution by having the correction table for abnormal application in accordance with the flow channel 4. Next, the correction table and specific calculations of the embodiment will be described in more detail.

As described above, in the present embodiment, as a method of calculating the cross-sectional average flow velocity of the flow channel 4 according to the eight flow velocities of the eight side lines M, a calibration experiment or the like is performed, , And calculating a cross-sectional average flow velocity according to the sum.

A meter factor MF which depends on the degree of drift (the degree of bias of the eight flow velocity measurement values) in addition to the weight coefficient Wi of the correction table described above, the area factor area factor AF or the like to finally calculate the flow rate Q as shown in the following equation (3). In addition, in the equation 3, the inside diameter of the tube is DI.

In the ultrasonic flowmeter 1 according to the embodiment, calibration experiments are carried out and optimum weighting coefficients Wi = 1 to 8 are obtained in advance. In the case where the measurement is normally performed on the eight side lines M, the flow velocity value vi and the weighting coefficient Wi = Accurate flow values can be calculated using the correction values multiplied by 1 to 8.

In order to calculate a reliable flow rate by using only the flow velocity value vi of the seven side lines M excluding one side line M among the eight side lines M, an optimal weight coefficient Wi = 1 to 7 is calculated beforehand, A reliable flow rate can be calculated even when the flow velocity value vi is abnormal.

In addition, when calculating the flow rate using only the flow velocity value vi of the seven side lines M out of the eight side lines M, an appropriate weighting factor Wi = 1 to 7 is one flow velocity value vi of the first side line M1 to the eighth side line M8 If not used, prepare 8 correction tables. The accuracy (accuracy) of the flow value calculated using the flow velocity value vi of the seven side lines M is slightly lower than the flow flow value calculated using the flow velocity value vi of the eight side lines M, but the accuracy of the required flow rate value It is sufficient to carry out a calibration experiment in advance and find an appropriate weighting coefficient Wi for each of the cases in which the condition range of the property of the fluid is limited.

It is also conceivable to calculate the flow velocity value vi of each of the side lines M when the characteristics of the fluid and the flow rate value are changed using software and simulation, and to provide these calculated values to the database. Using this database, the flow value can be retrieved from the measured flow rate vi on each side line M (data library method). When a database is searched, the most reliable flow rate value can be determined by performing a search at a high speed according to the following method.

The flow velocity value vi of each of the side lines M is converted into a dimensionless number by dividing the flow velocity value vi of each of the side lines M by the reference value, with the maximum value among the eight flow velocity values vi of the eight side lines M as a reference value, do. This non-dimensional number is between 0.0 and 1.0. Also, the flow rate value vi is divided into a reference value and a numerical value is registered in the database. As a key for searching the database, a hash value to be described later is calculated in advance and registered in the database.

The non-dimensionalized value on each side line M is converted to a number that is one digit shorter than the number of significant digits to be sought. Then, the eight numbers that are converted in this way are juxtaposed and the combined number is used as a hash key. As an example, it is executed as follows.

Let us consider a case where the flow rate value vi of the eight side lines M is 1.000, 1.198, 1.197, 0.998, 0.999, 1.196, 1.199 and 0.999, and the calculated flow rate value is 1.123 and the desired number of significant digits is four digits.

In this case, since the maximum value of the measured flow velocity value vi is 1.199, dividing each flow velocity value vi by this maximum value results in 0.8340, 0.9992, 0.9983, 0.8324, 0.8332, 0.9975, 1.0000 and 0.8332. When it rounds to three digits (for example, it cuts the fourth decimal place), it is 0.834, 0.999, 0.998, 0.832, 0.833, 0.997, 1.000, 0.833.

In this case, the hash key is 08340999099808320833099710000833, and at least the hash key, the reference value 1.199, the flow value 1.123, and three items are registered in the storage circuit 7 as a database, and are extracted at a high speed by the hash index. By adopting the hash key as described above, a plurality of pieces of data having different flow velocity values and flow values barely have the same hash value.

In practice, when the flow velocity is measured using eight lines M, a flow velocity value vi slightly distant from the above is observed due to measurement errors and the like. For example, 0.9998, 1.19781, 1.1968, 0.9978, 0.9988, 1.1988, 0.9988. In this example, each flow value vi is slightly different from the flow rate described above, but the hash key is the same in this case as well. In this case, when a hash key is searched, data of several flow values having a very close flow velocity distribution are searched. Since these are data of a flow value close to a very close flow velocity distribution A, the average value of the flow values It is possible to obtain a reliable flow rate value. In this case, if the maximum value of the measured flow rate vi is 1.998, the retrieved reference value is 1.198, and the retrieved flow rate value is 1.123, 1.123 × 1.1998 / 1.198 = about 1.124 is the most reliable flow rate value with four significant digits.

In addition, although the above description has been described using a decimal number to simplify the description, a more detailed database can be created by using the value vi as a binary number and selecting the desired number of significant digits and the number of digits to be rounded.

With respect to the hash keys derived from the flow velocity values vi of the seven survey lines M in the data library method as described above, eight kinds of hash keys are registered in the database and are searchable, so that only seven of the eight survey lines M are measured normally , It is possible to obtain a reliable flow rate value as in the case where the eight side lines M are normal.

As described above, according to the ultrasonic flowmeter 1 of the present embodiment, when one of the first side line M1 to the eighth side line M8 fails, the flow velocity of the failed side line M is excluded from the calculation, It is possible to prevent the degree of the calculated flow rate from being lowered even when the side line M is broken. Therefore, according to the ultrasonic flowmeter 1 of the embodiment, it is possible to continue the measurement without lowering the flow rate until the replacement work of the broken line M is performed.

(Other Embodiments)

In the above-described embodiment, when an abnormality occurs in one of the eight side lines M, the arithmetic operation is performed using one of the correction tables for eight types of abnormalities. The present invention is not limited to the above-described embodiment, but it is also possible to calculate the flow rate value only by using the flow rates of six lines M out of the eight line M when an abnormality occurs in the two line M, as in the above-described embodiment.

When the calculation is performed using the flow rates of the six side lines M, since the degree of the flow rate tends to be further lowered, in order to secure the required degree of flow rate to the same degree, the weight coefficient is previously obtained It becomes necessary to put it. Various kinds of abnormal test correction tables having different weighting coefficients according to the combination of the broken line M are stored in the memory circuit 7 in the present embodiment.

Therefore, even when two lines M of the eight lines M have an error, it is possible to prepare different types of abnormal correction tables having different weighting coefficients for each combination of the two lines M, It is possible to prevent the degree of the calculated flow rate from being lowered.

Even in the case where an abnormality occurs in three of the eight side lines M in the same manner as above, even if three side lines M are broken up by preparing various types of abnormality correction tables for each combination of the three side lines M in which an anomaly occurs, Can be prevented from being lowered.

By arranging various kinds of abnormality correction tables having different weighting coefficients for each combination in consideration of the combination of the ideal line M for each number of the abnormal line M, the present invention can be applied to, for example, Even if M becomes abnormal, the decrease in the degree of the flow rate can be suppressed.

Further, in the ultrasonic flowmeter of the above-described embodiment, a pair of ultrasonic wave transmitting and receiving devices 5 constituting a sideline are arranged at positions opposed to each other with the flow path 4 therebetween. However, the present invention is not limited to this configuration, The present invention may be applied to a reflection type flow meter arranged to reflect light from a light source.

1: Ultrasonic flow meter 3: Circular tube
4: Euro 5: Ultrasonic transceiver
7: memory circuit 8: decision circuit
9: Operation circuit

Claims (5)

Two or more pairs of ultrasonic wave transmitters and receivers disposed at intervals in the flow path so as to generate a plurality of sidewall lines which are opposed to each other with a flow path of a fluid to be measured being disposed therebetween and made by a predetermined ultrasonic wave reception signal;
A first arithmetic processing unit for calculating a flow velocity of each of the lateral lines in accordance with the measured value of the ultrasonic wave transmitter and receiver;
A determination circuit that determines that the corresponding sideline is abnormal when the measurement can not be performed on the sideline and determines that the sideline is abnormal when the flow velocity of the sideline is out of a predetermined range;
A correction table having coefficients for weighting flow velocities in each of the lateral lines to correct the flow velocity in each of the lateral lines, a normal time correction table used when all the lateral lines are normal, and a correction table A storage circuit in which various kinds of correction tables are stored;
And a second arithmetic processing unit for calculating an average flow velocity as an average of a plurality of correction values for multiplying the flow velocity in each of the lateral lines by a correction table coefficient,
Wherein the second calculation processing unit is configured to calculate the flow rate of the flow rate in the normal remaining remaining lateral line and the flow rate in the abnormal lateral line based on the average flow rate calculated using the abnormality correction table when the determination circuit determines that the lateral line is abnormal, Is calculated based on a correction value prepared in advance for the fault of the sideline. 2. The image processing apparatus according to claim 1, wherein the memory circuit has a plurality of different types of abnormality correction tables that are different for each one of the lateral lines excluded from the second arithmetic processing unit operation, The abnormality correction table corresponding to the sideline determined to be abnormal is selected. 2. The image processing apparatus according to claim 1, wherein the storage circuit has a plurality of types of abnormal test correction tables corresponding to combinations of a plurality of side lines excluded in the second operation processing section operation, The abnormality correction table corresponding to a combination of a plurality of line segments determined to be abnormal in the table is selected. A flow rate calculation method for calculating a flow rate of a flow path by using a plurality of sidewalls having a pair of ultrasonic wave transducers installed in the flow path,
A first calculation step of calculating a flow velocity of a sideline line according to a value measured by the ultrasonic wave transmitter and receiver;
A determination step of determining that the corresponding sideline is abnormal if the measurement can not be performed on the sideline and determining that the sideline is abnormal when the flow velocity of the sideline is out of a predetermined range;
A correction table having a coefficient for weighting the flow velocity on each of the lateral lines to correct the flow velocity on each of the lateral lines, a normal time correction table used when all the lateral lines are normal, and a correction table And second calculation steps of calculating an average flow velocity as an average of a plurality of correction values by multiplying a flow velocity in each of the plurality of sideways by a correction table coefficient,
The flow rate is calculated in accordance with an average flow rate calculated using a flow rate of a normal side line excluding a flow rate of an abnormal side line and an abnormal flow rate correction table when it is determined that one of the plurality of side lines is abnormal in the second calculation step . The flow rate calculation method according to claim 4, wherein the second calculation step calculates a flow rate by selectively using one of the abnormality correction tables in the various types of abnormality correction tables for each of the sidelines determined to be abnormal in the determination step Way.

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