Flow measurement and correction system using ultrasound

Abstract

The present disclosure relates to a flow measurement and correction system using ultrasonic waves, the flow measurement and correction system comprising: a measurement tube body having a horizontal straight tube and an inlet tube and an outlet tube communicating with the straight tube at 90 degrees; the first ultrasonic transceiver and the second ultrasonic transceiver are respectively arranged on the outer part of one closed end of the straight pipe and the outer part of the other closed end of the straight pipe; the flow measuring device is used for measuring the flow velocity of fluid flowing through the measuring pipe main body and calculating the flow of the fluid according to the measured flow velocity; and the signal processing device is used for enabling a first ultrasonic signal transmitted from the first ultrasonic transceiver and a second ultrasonic signal transmitted from the second ultrasonic transceiver to pass zero so as to maintain the same measurement point.

Description

Technical Field

[0001] The present disclosure relates to a flow measurement and correction system using ultrasonic waves that can accurately and precisely measure the flow rate of a chemical solution supplied to a semiconductor manufacturing process. Background Art

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] Generally, as a flowmeter for measuring a flow rate, a differential pressure flowmeter using Bernoulli's theorem, an electromagnetic flowmeter using Faraday's law, and an ultrasonic flowmeter using a Doppler method and a time difference method are used.

[0004] Among the aforementioned flow meters, the ultrasonic flow meter measures the flow rate by the ultrasonic arrival time difference. That is, an ultrasonic sensor disposed on the outside of one end of a pipe through which the fluid flows transmits ultrasonic waves to the fluid flowing into the pipe. Another ultrasonic sensor disposed on the outside of the other end of the pipe receives the reflected wave. The flow rate is then measured by the ultrasonic arrival time difference that varies according to the flow velocity of the fluid.

[0005] This ultrasonic flow meter is easy to manage and maintain because the ultrasonic sensor is set outside the pipe and has the advantage of not interfering with the flow of the fluid. In particular, compared with other flow meters, ultrasonic flow meters have been widely used because there is no direct interference in particle generation, which is important in the semiconductor manufacturing process.

[0006] However, ultrasonic flow meters are susceptible to elements that refract ultrasonic waves because a process is required for ultrasonic waves to pass through the fluid. In other words, ultrasonic waves are highly vulnerable to the bubble phenomenon, in which the refraction of ultrasonic waves can occur inside the pipe, resulting in poor measurement precision and accuracy.

[0007] That is, when the ultrasonic flow meter measures the time it takes for ultrasonic waves to travel in a pipe, there is a difference between the time it takes for ultrasonic waves to travel through the pipe when there is no refractive element inside the pipe and the time it takes for ultrasonic waves to travel through the pipe when refractive elements (such as bubbles) appear inside the pipe.

[0008] In other words, a conventional ultrasonic flow meter includes a horizontal pipe through which a fluid flows, a first ultrasonic sensor disposed on the outside of one end of the pipe and a second ultrasonic sensor disposed on the outside of the other end of the pipe, and the first ultrasonic sensor transmits ultrasonic waves to the second ultrasonic sensor.

[0009] At this time, if there is no refractive element inside the pipe, the ultrasonic wave reaches the second ultrasonic sensor without being refracted. However, if a refractive element such as a bubble appears inside the pipe, the time it takes for the ultrasonic wave emitted from the first ultrasonic sensor to reach the second ultrasonic sensor changes, so that not only errors in flow measurement may occur, but also the accurate speed of the ultrasonic wave may not be measured.

[0010] In addition, the conventional ultrasonic flowmeter measures the flow rate by searching for a frequency only when the second ultrasonic sensor receives the ultrasonic wave transmitted from the first ultrasonic sensor to filter the received ultrasonic signal. When the temperature of the fluid changes rapidly, the ultrasonic wave transmission time changes, so that there is a problem of losing the accurate measurement point. In addition, since a noise signal of a predetermined frequency is measured, there is a problem of flow measurement errors occurring.

[0011] In addition, since the conventional ultrasonic flow meter measures the flow rate using only ultrasonic waves transmitted from the first ultrasonic sensor, there is a problem that flow rate measurement errors occur and it is difficult to measure the flow rate accurately and precisely.

[0012] In other words, when the temperature of the fluid flowing through the pipe changes, the speed of the ultrasonic wave also changes, but at this time, there is a problem that the measuring unit temporarily loses the position of the ultrasonic wave waveform. In the process of rechecking the ultrasonic wave waveform, since the measuring unit measures the noise signal, not only errors in flow measurement occur, but also it is difficult to measure the flow accurately and precisely.

[0013] In addition, in a conventional ultrasonic flow meter, since the cycle of the ultrasonic wave transmitted from the first ultrasonic sensor and the cycle of the ultrasonic wave oscillated by the ultrasonic oscillator are not the same, the speed of the ultrasonic wave is identified slightly differently at the position where the ultrasonic wave has been measured, resulting in a problem of inaccurately and precisely measuring the flow rate.

[0014] Meanwhile, in order to reduce errors due to changes in the ultrasonic waveform of the ultrasonic flow meter, even if the measurement point of the ultrasonic waveform changes, it is necessary to accurately find and maintain a reference signal as a basis for measuring the ultrasonic time difference.

[0015] If the start signal is found accurately, the frequency of the ultrasonic wave and the time difference of the ultrasonic wave can be obtained based on the specific number of cycle signals of the ultrasonic wave waveform using the time-to-digital converter (TDC) function of the field programmable gate array (FPGA) IC, which is the basis for time measurement.

[0016] As a conventional method of finding a start signal and filtering a noise waveform, the second ultrasonic sensor receiving the ultrasonic wave searches for a frequency of an ultrasonic waveform that is the same as the frequency transmitted by the first ultrasonic sensor, and the FPGA IC confirms the frequency. The second ultrasonic sensor can identify a frequency that is different from the frequency (e.g., 2Mhz) confirmed by the FPGA IC as a noise waveform and filter it, and then find a signal with the same frequency as the measurement waveform.

[0017] Here, since the noise waveform does not match the natural frequency of the ultrasonic signal and changes continuously, the noise waveform can be filtered by this technology.

[0018] In addition, as a method of measuring a cycle signal of a specific number of ultrasonic waves, which is the basis of ultrasonic time measurement, a technique of inferring a specific number by analyzing the size of an ultrasonic wave waveform using an A / D transducer is adopted.

[0019] However, due to other environmental factors such as bubbles or temperature, the size (amplitude) of the ultrasonic signal may change inside the pipe through which the fluid flows, which may change the measurement reference position due to changes in the recognition of the size of the waveform, thereby causing a factor to change the flow measurement offset.

[0020] Furthermore, the measurement position is changed by factors (temperature and chemical solution) that affect the matching of the first ultrasonic sensor and the second ultrasonic sensor, and these changes become factors that cause defects in ultrasonic flow measurement, and therefore become factors to be managed when using an ultrasonic flow meter. Summary of the invention

[0021] An object of the present disclosure is to provide a flow measurement and calibration system using ultrasonic waves, which is capable of measuring an accurate flow rate of a fluid flowing through a pipe.

[0022] Another object of the present disclosure is to provide a flow measurement and correction system using ultrasonic waves, which is capable of minimizing flow measurement errors by constantly maintaining a measurement point of an ultrasonic sensor.

[0023] The technical objectives to be achieved by the present disclosure are not limited to the above objectives, and those skilled in the art will easily understand other technical objectives not described above based on the following disclosure of the present disclosure.

[0024] This section provides a summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0025] According to one aspect of the present disclosure, a flow measurement and correction system using ultrasonic waves is provided, the flow measurement and correction system using ultrasonic waves comprising: a measuring tube body, the measuring tube body having a horizontal straight tube and an inlet tube and an outlet tube connected to the straight tube at 90 degrees; a first ultrasonic transceiver and a second ultrasonic transceiver, the first ultrasonic transceiver and the second ultrasonic transceiver being respectively arranged on the outside of one closed end of the straight tube and on the outside of the other closed end; a flow measuring device, the flow measuring device being used to measure a flow velocity flowing through the measuring tube body and calculate a flow rate of the fluid by the measured flow velocity; and a signal processing device, the signal processing device being used to make a first ultrasonic signal transmitted from the first ultrasonic transceiver and a second ultrasonic signal transmitted from the second ultrasonic transceiver pass through zero to maintain the same measurement point.

[0026] In a flow measurement and correction system using ultrasonic waves according to one aspect of the present disclosure, the first ultrasonic transceiver can transmit the first ultrasonic signal to the second ultrasonic transceiver and receive the second ultrasonic signal transmitted by the second ultrasonic transceiver, and the second ultrasonic transceiver can transmit the second ultrasonic signal to the first ultrasonic transceiver and receive the first ultrasonic signal transmitted by the first ultrasonic transceiver.

[0027] In a flow measurement and correction system using ultrasonic waves according to an aspect of the present disclosure, the flow measurement device may include: a transducer that receives the first ultrasonic signal received by the second ultrasonic transceiver and the second ultrasonic signal received by the first ultrasonic transceiver, respectively, and generates digitized ultrasonic waveform data by zero-crossing the received first ultrasonic signal and the second ultrasonic signal; an FPGAIC that receives each ultrasonic waveform data from the transducer to calculate the arrival time of the first ultrasonic signal at the second ultrasonic transceiver and the arrival time of the second ultrasonic signal at the first ultrasonic transceiver, and measures the time difference between the measured zero-crossing points to generate time difference data; and a control unit that compares a predetermined reference value K with the measured time difference value between the measured zero-crossing points (An or Bn; A’n or B’n) of the first ultrasonic signal and the second ultrasonic signal, and takes the first ultrasonic signal and the second ultrasonic signal when the measured time difference value is within the range of the reference value K, calculates the flow velocity of the fluid through the moving time of the measured first ultrasonic signal from the first ultrasonic transceiver to the second ultrasonic transceiver and the moving time of the second ultrasonic signal from the second ultrasonic transceiver to the first ultrasonic transceiver, and calculates the flow rate of the fluid using the calculated fluid velocity. The control unit may be configured to: detect a change in the velocity of the ultrasonic waves of the fluid flowing through the horizontal pipe body, and correct the measured moving times tXY, tYX of the first ultrasonic signal and the second ultrasonic signal by using the ratio of the changed ultrasonic velocity to the ultrasonic velocity of the fluid set as a reference to eliminate flow measurement errors. The control unit may calculate the ratio of the changed ultrasonic velocity to the ultrasonic velocity set as a reference, which is equal to the ultrasonic velocity set as a reference divided by the changed ultrasonic velocity, and correct the moving times tXY, tYX of the first ultrasonic signal and the second ultrasonic signal measured by multiplying the moving time tXY of the first ultrasonic signal and the moving time tYX of the second ultrasonic signal where an error occurs by the reciprocal of the ratio of the ultrasonic velocity set as a reference to the changed ultrasonic velocity.

[0028] In a flow measurement and correction system using ultrasonic waves according to an aspect of the present disclosure, when the reference time difference between the measured zero-crossing points is referred to as TA0, the reference value K may be in the range of 0.9TA0 < K < 1.1A0.

[0029] In a flow measurement and correction system using ultrasound according to one aspect of the present disclosure, when the measured zero crossing points An, A'n of the first ultrasonic signal and the measured zero crossing points Bn, B'n of the second ultrasonic signal are taken, the measured zero crossing point An-A'n is called TAn, and the measured zero crossing point Bn-B'n is called TBn, erroneous measurements can be prevented by preferentially taking a value that satisfies -α<TAn-TBn<+α, wherein α can be an arbitrary set value considering the flow rate of the measuring tube body.

[0030] In a flow measurement and correction system using ultrasonic waves according to one aspect of the present disclosure, the signal processing device may include: a detection unit that receives the first ultrasonic signal and the second ultrasonic signal through the first ultrasonic transceiver and the second ultrasonic transceiver to detect the first ultrasonic signal and the second ultrasonic signal transmitted from the first ultrasonic transceiver and the second ultrasonic transceiver; a conversion unit that includes an A / D converter for sampling the first ultrasonic signal and the second ultrasonic signal detected by the detection unit a predetermined number of times per cycle to detect the waveform of the detected signal, and determining a first cycle ultrasonic signal based on the detected waveform of the first ultrasonic signal and the second ultrasonic signal; and a measuring unit that calculates the flow rate at a measurement point at a position moved by a set measurement cycle based on the first cycle ultrasonic signal determined by the conversion unit. The conversion unit may sample the signal of at least more cycles than the measurement cycle before and after the measurement point, and compare the sum of the sampled values ​​of each cycle to determine the first cycle ultrasonic signal.

[0031] In the flow measurement and correction system using ultrasonic waves according to one aspect of the present disclosure, the detection unit may search for and detect a signal having the same frequency as a set transmission frequency of the first ultrasonic wave signal and the second ultrasonic wave signal.

[0032] In a flow measurement and correction system using ultrasound according to one aspect of the present disclosure, when the sum of the sampling values ​​of each cycle is equal to or greater than a set value, the conversion unit can compare the sum of the sampling values ​​of each cycle to determine the first cycle ultrasonic signal, and when the sum of the sampling values ​​of each cycle continuously increases for three or more cycles, the conversion unit can compare the sum of the sampling values ​​of each cycle to determine the first cycle ultrasonic signal.

[0033] In the flow measurement and correction system using ultrasonic waves according to one aspect of the present disclosure, the conversion unit may further include an amplification unit that amplifies and adjusts the amplitude so that the sum of the sampling values ​​of each cycle is equal to a set standing wave value.

[0034] In the flow measurement and correction system using ultrasonic waves according to one aspect of the present disclosure, the conversion unit may further include a range unit which outputs the detected ultrasonic wave signal in real time based on the sampling value of each cycle.

[0035] According to an exemplary embodiment of the present disclosure, it is possible to provide an effect of measuring the accurate flow rate of the fluid flowing inside the pipe by taking only the undeformed ultrasonic wave to obtain the accurate flow velocity of the measuring fluid even if the ultrasonic wave is deformed by bubbles generated in the measuring fluid inside the pipe.

[0036] According to an exemplary embodiment of the present disclosure, an effect of minimizing flow measurement errors may be provided by sampling a received ultrasonic signal using an A / D transducer to accurately detect a first cycle ultrasonic signal and analyzing multiple channels of the same ultrasonic signal using an FPGA IC. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and other aspects, features and other advantages of the present disclosure will be more clearly understood through the following detailed description taken in conjunction with the accompanying drawings, in which:

[0038] Figure 1 is a diagram schematically showing a flow measurement and correction system using ultrasonic waves related to the present disclosure;

[0039] Figure 2 It is shown from Figure 1 A diagram of a first ultrasonic signal and a second ultrasonic signal transmitted by a first ultrasonic transceiver and a second ultrasonic transceiver, wherein Figure 2 (a) shows an ultrasonic standing wave signal, and Figure 2 (b) shows the deformation of the ultrasonic standing wave signal;

[0040] Figure 3 is a diagram for describing obtaining time difference data between measured zero crossing points according to the present disclosure;

[0041] Figure 4 is a diagram for describing obtaining other time difference data between measured zero crossing points according to the present disclosure;

[0042] Figure 5 It is schematically shown Figure 1 A diagram of another exemplary embodiment of a signal processing device of ; and

[0043] Figure 6It is schematically shown Figure 1 FIG. 1 is a diagram of another exemplary embodiment of a signal processing device. DETAILED DESCRIPTION

[0044] Hereinafter, exemplary embodiments for implementing a flow measurement and correction system using ultrasonic waves according to the present disclosure will be described in detail with reference to the accompanying drawings.

[0045] However, it is not to be said that the exemplary embodiments of the inherent technical spirit of the present disclosure are limited to the exemplary embodiments described below, and the technical spirit disclosed includes a scope that can be easily proposed by a person skilled in the art by replacing or changing the exemplary embodiments described below based on the inherent technical spirit of the present disclosure.

[0046] Furthermore, since the terms used hereinafter are selected for ease of description, the terms are not limited to dictionary meanings and should be appropriately interpreted as meanings consistent with the technical spirit of the present disclosure in order to grasp the inherent technical spirit of the present disclosure.

[0047] In the accompanying drawings, Figure 1 is a diagram schematically showing a flow measurement and correction system using ultrasonic waves related to the present disclosure.

[0048] Reference Figure 1 A flow measurement and correction system using ultrasonic waves related to the present disclosure includes a measuring tube body 10 and first and second ultrasonic transceivers 21 and 22 provided at an inlet side and an outlet side of the measuring tube body 10 .

[0049] In addition, the flow measurement and correction system using ultrasonic waves related to the present disclosure further includes a flow measurement device 30 and a signal processing device 40 .

[0050] First, the measuring tube body 10 includes a horizontal straight tube 11 , an inlet-side tube 12 fused to one closed end of the straight tube 11 , an outlet-side tube 13 fused to the other closed end of the straight tube 11 , an inlet tube 14 , and an outlet tube 15 .

[0051] At this time, the inlet pipe 14 is connected to the straight pipe 11 at 90 degrees, and similarly, the outlet pipe 15 is connected to the straight pipe 11 at 90 degrees, so that the measuring tube body 10 has a crank shape, that is, an approximately "U" shape.

[0052] Furthermore, the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 are respectively disposed in the inlet side pipe 12 and the outlet side pipe 13 as shown to face each other, and the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 transmit and receive the first ultrasonic signal and the second ultrasonic signal, respectively.

[0053] That is, the first ultrasonic transceiver 21 transmits the first ultrasonic signal to the second ultrasonic transceiver 22 and receives the second ultrasonic signal transmitted by the second ultrasonic transceiver 22. In addition, the second ultrasonic transceiver 22 transmits the second ultrasonic signal to the first ultrasonic transceiver 21 and receives the first ultrasonic signal transmitted by the first ultrasonic transceiver 21.

[0054] Here, the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 are general ultrasonic sensors, and in the present disclosure, a detailed description of the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 will be omitted.

[0055] Meanwhile, the flow measurement device 30 includes a transducer 32 , an FPGA IC 34 , and a control unit 36 ​​as shown in the figure.

[0056] The transducer 32 receives the first ultrasonic signal received by the second ultrasonic transceiver 22 and the second ultrasonic signal received by the first ultrasonic transceiver 21 , respectively, and generates digitalized corresponding ultrasonic waveform data by making the received first and second ultrasonic signals pass through zero.

[0057] The FPGA IC 34 receives each ultrasonic waveform data from the transducer 32 to measure the arrival time of the first ultrasonic signal arriving at the second ultrasonic transceiver 22 and the arrival time of the second ultrasonic signal arriving at the first ultrasonic transceiver 21 .

[0058] In addition, the FPGA IC 34 confirms the timing of the zero-crossing point in each ultrasonic waveform data received from the transducer 32 .

[0059] That is, when the start signal of the first ultrasonic signal is input, the FPGA IC 34 measures the time from the start signal to each measured zero crossing point to calculate the time difference between the measured zero crossing points. In addition, when the start signal of the second ultrasonic signal is input, the FPGA IC 34 measures the time from the start signal to each measured zero crossing point to generate time difference data for calculating the time difference between the measured zero crossing points.

[0060] At this time, the FPGA IC 34 measures the arrival times of the first ultrasonic wave signal and the second ultrasonic wave signal by applying a conventional time-to-digital converter (TDC) method capable of measuring the time to measure the zero-crossing point.

[0061] The control unit 36 ​​controls the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 so that the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 can alternately transmit the first ultrasonic signal and the second ultrasonic signal, and the control unit 36 ​​enables the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 to repeatedly transmit and receive the first ultrasonic signal and the second ultrasonic signal multiple times.

[0062] In addition, the control unit 36 ​​receives time difference data of the first ultrasonic wave and the second ultrasonic wave from the FPGA IC 34 .

[0063] At this time, if the time K of the frequency cycle of the first ultrasonic signal and the second ultrasonic signal transmitted by the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 is incorrect in the time difference data of the first ultrasonic signal and the second ultrasonic signal, the control unit 36 ​​determines the ultrasonic data as erroneous, and if not, identifies the ultrasonic data as normal data.

[0064] In addition, when the time K of the frequency cycle transmitted by the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 is correct in the time difference data of the first ultrasonic signal and the second ultrasonic signal, it is identified as normal data, and the control unit 36 ​​receives the movement time tXY from the first ultrasonic transceiver 21 to the second ultrasonic transceiver 22 and the movement time tYX from the second ultrasonic transceiver 22 to the first ultrasonic transceiver 21 from the FPGA IC 34.

[0065] At this time, a movement time tXY of the first ultrasonic signal from the first ultrasonic transceiver 21 to the second ultrasonic transceiver 22 and a movement time tYX of the second ultrasonic signal from the second ultrasonic transceiver 22 to the first ultrasonic transceiver 21 may be represented by Equations 1 and 2 below.

[0066] [Equation 1]

[0067] tXY=L / (C+V)

[0068] [Equation 2]

[0069] tYX=L / (CV)

[0070] (Here tXY: the travel time of the first ultrasonic signal from the first ultrasonic transceiver to the second ultrasonic transceiver, tYX: the travel time of the second ultrasonic signal from the second ultrasonic transceiver to the first ultrasonic transceiver, and C: the sound velocity of the measurement fluid.)

[0071] In addition, the control unit 36 ​​can calculate the flow velocity by inputting the movement time tXY of the first ultrasonic signal from the first ultrasonic transceiver 21 to the second ultrasonic transceiver 22 and the movement time tYX of the second ultrasonic signal from the second ultrasonic transceiver 22 to the first ultrasonic transceiver 21 into the following equation 3, and calculate the flow rate of the measured fluid by inputting the calculated flow velocity into the following equation 4.

[0072] [Equation 3]]

[0073]

[0074] (Here, V: flow velocity of the measured fluid, and L: distance between the first ultrasonic transceiver and the second ultrasonic transceiver.)

[0075] [Equation 4]

[0076] Q=A×V

[0077] (Here, Q: flow rate, A: cross-sectional area of ​​the horizontal pipe body, V: flow velocity of the measured fluid.)

[0078] At this time, the control unit 36 ​​can average the movement time tXY of the first ultrasonic signal from the first ultrasonic transceiver 21 to the second ultrasonic transceiver 22 and the movement time tYX of the second ultrasonic signal from the second ultrasonic transceiver 22 to the first ultrasonic transceiver 21, and input each averaged movement time into Equation 3 to calculate a more accurate flow rate.

[0079] Meanwhile, in equations 1 and 2, in the moving times tXY and tYX of the first ultrasonic signal and the second ultrasonic signal, when the fluid flowing through the horizontal pipe body changes, even if the velocity of the fluid is the same, the measured moving times tXY and tYX of the first ultrasonic signal and the second ultrasonic signal change. This does not interfere with the accurate measurement of the flow rate.

[0080] However, if the fluid flowing through the horizontal pipe body is the same and the actual flow rate is the same, but the measured movement times tXY and tYX of the first ultrasonic signal and the second ultrasonic signal are different, when the flow rate according to Equation 3 has an error, an error in the measured flow rate eventually occurs.

[0081] The change in ultrasonic velocity (which is the cause of these errors) can be confirmed according to Equation 5 below, but occurs when there is a change in the density or temperature of the fluid flowing through the horizontal pipe body.

[0082] [Equation 5]

[0083]

[0084] (Here, C: first ultrasonic signal velocity and second ultrasonic signal velocity, K: temperature (bulk modulus), and ρ: density.

[0085] The present disclosure can eliminate these flow measurement errors.

[0086] Specifically, the change in the velocity of the ultrasonic wave of the fluid flowing through the horizontal pipe body is detected, and the flow measurement error can be corrected by correcting the measured movement times tXY and tYX of the first ultrasonic signal and the second ultrasonic signal using the ratio of the changed ultrasonic wave velocity to the ultrasonic wave velocity of the fluid set as a reference.

[0087] That is, the control unit 36 ​​can calculate the ratio of the changed ultrasonic velocity to the ultrasonic velocity set as a reference (the ratio = ultrasonic velocity set as a reference / changed ultrasonic velocity), and can eliminate flow measurement errors by using the calculated ratio to correct the erroneous first ultrasonic signal movement time tXY and the second ultrasonic signal movement time tYX.

[0088] This is performed by multiplying the first ultrasonic signal movement time tXY and the second ultrasonic signal movement time tYX where the error occurs by the inverse of the ratio of the ultrasonic velocity set as a reference to the changed ultrasonic velocity.

[0089] In the present disclosure, the ultrasonic velocity of the fluid is periodically detected by the difference between the time when each ultrasonic sensor outputs an oscillation signal and the time until the ultrasonic sensor receives the oscillation signal and recognizes the oscillating ultrasonic sensor.

[0090] Since the distance between the ultrasonic sensors is known, the ultrasonic velocity can be determined using only the time difference.

[0091] When the difference between the periodically detected ultrasonic velocity and the ultrasonic velocity of the fluid set as a reference is confirmed, the occurrence of error in the flow measurement is identified and corrected.

[0092] When the fluid in the horizontal pipe body is stationary, the ultrasonic velocity of the fluid set as a reference is the ultrasonic velocity calculated by Equations 1 and 2 based on tXY and tYX measured in the same manner.

[0093] When the temperature or density of the fluid changes and the ultrasonic velocity changes, a flow measurement value from which errors are removed can be obtained by confirming the ratio of the difference between the changed ultrasonic velocity and the reference ultrasonic velocity.

[0094] The process of periodically sensing the ultrasonic wave velocity is performed while the fluid flows, and when the fluid flows, a difference between tXY and tYX occurs due to the velocity of the fluid.

[0095] Therefore, compared with the case where the fluid is stationary, the periodically detected ultrasonic wave velocity has an error due to the difference between tXY and tYX generated by the velocity of the fluid.

[0096] However, the error in the ultrasonic wave velocity caused by the difference between tXY and tYX generated by the velocity of the fluid is very small compared to the error in the ultrasonic wave velocity generated by the change in temperature or density, and is ignored.

[0097] Meanwhile, the flow measurement device 30 is provided with an input unit 38 capable of controlling the operation of the control unit 36 ​​, so that the operation of the control unit 36 ​​can be controlled.

[0098] Hereinafter, a flow rate measurement method using the above-mentioned flow measurement and correction system using ultrasonic waves will be described.

[0099] First, the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 are operated, and a fluid is introduced into the inlet pipe 14 of the measuring tube body 10 .

[0100] At this time, the control unit 36 ​​controls the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 to alternately transmit and receive the first ultrasonic signal and the second ultrasonic signal in the same manner. Preferably, the control unit 36 ​​enables the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 to transmit and receive the first ultrasonic signal and the second ultrasonic signal multiple times for precision and accuracy of flow measurement.

[0101] Furthermore, the fluid introduced into the inlet pipe 14 is discharged through the outlet pipe 15 via the straight pipe 11 .

[0102] Meanwhile, when the fluid passes through the straight pipe 11 , the first ultrasonic signal from the first ultrasonic transceiver 21 passes through the fluid along the flow direction of the fluid in the straight pipe 11 , and the first ultrasonic signal passing through the fluid is received by the second ultrasonic transceiver 22 .

[0103] In addition, the second ultrasonic transceiver 22 receiving the first ultrasonic signal outputs the first ultrasonic wave to the transducer 32. At this time, the transducer 32 receiving the first ultrasonic signal makes the first ultrasonic wave of the first ultrasonic transceiver 21 pass through zero to digitize the first ultrasonic wave that passes through zero, such as Figure 3 Here, since the zero-crossing process is a well-known fact, its detailed description will be omitted.

[0104] In addition, as described above, when the second ultrasonic transceiver 22 receives the first ultrasonic signal of the first ultrasonic transceiver 21, the second ultrasonic transceiver 22 transmits the second ultrasonic signal to the first ultrasonic transceiver 21. At this time, the second ultrasonic signal passes through the fluid in the reverse flow direction of the fluid in the straight pipe 11, and the second ultrasonic signal passing through the fluid is received by the first ultrasonic transceiver 21.

[0105] In addition, the first ultrasonic transceiver 21 receiving the second ultrasonic signal outputs the second ultrasonic signal to the transducer 32, and the transducer 32 outputs the second ultrasonic signal as a square wave waveform, such as Figure 2 shown.

[0106] At this time, the transducer 32 receiving the second ultrasonic signal makes the second ultrasonic signal of the second ultrasonic transceiver 22 pass through zero and digitize, such as Figure 3 shown.

[0107] Here, the FPGA IC 34 inputs a start signal to the first ultrasonic signal, and measures the time from the start signal to each of the measurement zero-crossing points A1 and A2 to calculate a time difference between the measurement zero-crossing point A1 and the measurement zero-crossing point A2.

[0108] In addition, the FPGA IC 34 inputs a start signal to the second ultrasonic signal, and measures the time from the start signal to each of the measurement zero-crossing points A1 and A2 to calculate a time difference between the measurement zero-crossing point A1 and the measurement zero-crossing point A2.

[0109] At this time, the FPGA IC 34 calculates the time difference between the new measured zero-crossing points B1 and B2 according to the other first ultrasonic signal and the second ultrasonic signal through the same process as above (see Figure 4 ).

[0110] At the same time, the time difference data as described above is calculated by FPGA IC 34 using the same ultrasonic waveform for multiple time differences, and at this time, FPGA IC 34 averages the calculated data to improve the accuracy of the time difference data between the measured zero crossing points A and B obtained from the first ultrasonic signal and the second ultrasonic signal.

[0111] In addition, the control unit 36 ​​receives the time difference between the measured zero crossing points A1 - A2 and B1 - B2 of the first ultrasonic signal and the second ultrasonic signal from the FPGA IC 34 .

[0112] At this time, the control unit 36 ​​compares the predetermined reference frequency cycle time reference value K with the time difference between the measured zero crossing points A1-A2 and B1-B2 of the first ultrasonic signal and the second ultrasonic signal, respectively. If the time difference data between the measured zero crossing points A1-A2 and B1-B2 of each of the first ultrasonic signal and the second ultrasonic signal is within the range of the reference value K, the control unit 36 ​​identifies and adopts the corresponding first ultrasonic signal and the second ultrasonic signal as ultrasonic standing waves. If the time data of the first ultrasonic signal and the second ultrasonic signal exceeds the range of the reference value K, the control unit 36 ​​identifies and discards the corresponding first ultrasonic signal and the second ultrasonic signal as erroneous ultrasonic waves.

[0113] Here, when the control unit 36 ​​takes the first ultrasonic standing wave signal and the second ultrasonic standing wave signal within the range of the reference value K, the control unit 36 ​​receives from the FPGA IC 34 the movement time tXY of the first ultrasonic standing wave signal moving from the first ultrasonic transceiver 21 to the second ultrasonic transceiver 22 and the movement time tYX of the second ultrasonic standing wave signal moving from the second ultrasonic transceiver 22 to the first ultrasonic transceiver 21.

[0114] In addition, the control unit 36 ​​calculates the flow velocity of the measuring fluid through the movement time tXY of the first ultrasonic standing wave signal moving from the first ultrasonic transceiver 21 to the second ultrasonic transceiver 22 and the movement time tYX of the second ultrasonic standing wave signal moving from the second ultrasonic transceiver 22 to the first ultrasonic transceiver 21, and calculates the flow rate of the measuring fluid through the obtained flow velocity.

[0115] At this time, when the ultrasonic wave velocity changes according to the change of the temperature and density of the fluid, the error in the flow measurement can be eliminated according to the above method.

[0116] Meanwhile, in the present disclosure, the control unit 36 ​​may more accurately select the first ultrasonic signal and the second ultrasonic signal from among the first ultrasonic standing wave signal and the second ultrasonic standing wave signal through Equation 6 below.

[0117] [Equation 6]

[0118] 0.9TA 0 <TA X <1.1A 0

[0119] (Here, TA 0 : The reference time difference between the reference zero crossing points, and TA X : Measures the time difference between zero crossing points.

[0120] That is, the control unit 36 ​​can obtain more accurate first and second ultrasonic signals by selecting first and second ultrasonic signals satisfying Equation 6 from among the obtained first and second ultrasonic standing wave signals.

[0121] In addition, in the present disclosure, the control unit 36 ​​may more accurately select the first ultrasonic signal and the second ultrasonic signal from among the first ultrasonic standing wave signal and the second ultrasonic standing wave signal through the following Equation 7.

[0122] [Equation 7]

[0123] -a<TA n -TR n <+a

[0124] (Here α is an arbitrarily determined constant: in this disclosure, it is called 1% of the injected fluid, TA n =A n -A' n The time difference between n =B n -B' n The time difference between: A n and B n is the measured zero crossing point of the first ultrasonic wave, and A' n and B' n It is the measurement zero point of the second ultrasonic wave.

[0125] That is, the control unit 36 ​​can prevent errors in flow measurement by preferentially selecting the first ultrasonic signal and the second ultrasonic signal satisfying Equation 7 from among the obtained first ultrasonic standing wave signals and the second ultrasonic standing wave signals.

[0126] As described above, in the flow measurement method of the present disclosure, even if the ultrasonic wave is deformed due to bubbles generated in the measurement fluid inside the measurement tube body 10, the accurate flow rate of the fluid flowing inside the measurement tube body 10 can be measured by obtaining the accurate flow velocity of the measurement fluid by taking only the undeformed ultrasonic wave.

[0127] At the same time, the signal processing device 40 causes the first ultrasonic signal transmitted from the first ultrasonic transceiver 21 and the second ultrasonic signal transmitted from the second ultrasonic transceiver 22 to pass through zero to maintain the same measurement point.

[0128] The signal processing device 40 includes: Figure 1 A detection unit 42 , a conversion unit 46 and a measurement unit 44 are shown.

[0129] The detection unit 42 detects the first ultrasonic signal and the second ultrasonic signal received by the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 .

[0130] The detection unit 42 searches for and detects a signal having the same frequency as a set transmission frequency (for example, 2 MHz) transmitted from the first ultrasonic transceiver 21 and the second ultrasonic transceiver 22 .

[0131] The conversion unit 46 has an analog-to-digital (A / D) converter 48 for sampling the signal detected by the detection unit 42 a predetermined number of times per cycle to detect a detected signal waveform and determine a first cycle ultrasonic signal based on the detected signal waveform.

[0132] Specifically, when the detection unit 42 completes the search for the first ultrasonic signal and the second ultrasonic signal, the A / D converter 48 is used as the basis for time measurement to obtain 16 ultrasonic signals per cycle internally by sampling the 5 cycles before and after the cycle with a specific number.

[0133] Meanwhile, the conversion unit 46 can accurately specify the position of the ultrasonic signal by adding all 16 sampling values ​​per cycle and then comparing the added sampling values ​​with the sum of the sampling values ​​of the previous cycle.

[0134] The measuring unit 44 calculates the flow rate at the measuring point at the position moved by the set measurement cycle (for example, three cycles) based on the first cycle ultrasonic wave signal determined by the converting unit 46 .

[0135] Meanwhile, in the present disclosure, it is preferred that the conversion unit 46 compares the sum of the sampling values ​​of each cycle to determine the first cycle ultrasonic signal only when the sum of the sampling values ​​of each cycle is equal to or greater than the set value.

[0136] Specifically, the conversion unit 46 recognizes the ultrasonic waveform only when the sum of the sampling values ​​of each cycle is equal to or greater than a predetermined value, and the sum of the sampling values ​​from the first cycle ultrasonic signal to the next five cycles is maintained at a predetermined value or greater.

[0137] For example, if the sum of the sampling values ​​of the first and second cycles from the first cycle ultrasonic signal is sampled to a predetermined value or greater, but when the sum of the sampling values ​​of the third and fourth cycles is very small or very large, it is regarded as noise and the frequency search is performed again.

[0138] Meanwhile, in the present disclosure, when the sum of the sampling values ​​of each cycle increases continuously for three or more cycles, the conversion unit 46 determines the first cycle ultrasonic signal by comparing the sum of the sampling values ​​of each cycle. That is, since the ultrasonic standing wave is generated in the form of a waveform size of 1<2<3 cycles per cycle, signals not generated according to these rules are also regarded as noise and filtered.

[0139] At the same time, if Figure 5 As shown, the conversion unit 46 preferably further includes an amplification unit 50, which amplifies and adjusts the amplitude so that the sum of the sampling values ​​of each cycle is equal to the set standing wave value.

[0140] The amplification unit 50 stably achieves the effect of the present disclosure through the A / D converter 48. That is, in order to normally achieve the effect of the present disclosure through the A / D converter 48, the amplitude of the ultrasonic waveform needs to be always maintained at a constant level.

[0141] When the amplitude of the ultrasonic waveform decreases, the first waveform disappears, so that even if sampling is performed by the A / D converter 48, movement of the measurement point may occur.

[0142] Therefore, even if the amplitude changes due to the inflow of air bubbles into the measuring tube main body 10 and external environmental factors, the amplification unit 50 implements an automatic amplification function of always maintaining the amplitude at a constant level.

[0143] Specifically, the amplification unit 50 changes the amplification factor so that when the sum of the sampling values ​​of each cycle is less than or greater than the preset standing wave value, the sum of the sampling values ​​of each cycle is equal to the sum of the sampling values ​​of the standing wave to always maintain a constant amplitude. Therefore, the error caused by the change of the measurement waveform cycle due to the change of the amplitude of the first cycle can be reduced.

[0144] Similarly, the measurement point may move due to changing factors (temperature and density) even in the detection unit 42. When such movement occurs, the detection unit 42 activates the rescan function to find the frequency of the first cycle and the second cycle of the ultrasonic signal to the range in which the ultrasonic waveform can be measured from the start signal, so as to quickly find and measure the ultrasonic waveform even if the measurement point moves.

[0145] At the same time, if Figure 6 As shown, the conversion unit 46 preferably further includes a range unit 52 which outputs the detected ultrasonic signal in real time based on the sampling value of each cycle.

[0146] The scope unit 52 represents the monitoring procedure and graphs the ultrasonic signal in real time so that the user can visually check the ultrasonic signal without a separate meter.

[0147] While the present disclosure has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the disclosure as defined by the appended claims.

Claims

1. A flow measurement and correction system using ultrasonic waves, the flow measurement and correction system using ultrasonic waves comprising: A measuring tube body, the measuring tube body having a horizontal straight tube and an inlet tube and an outlet tube connected to the straight tube at 90 degrees; A first ultrasonic transceiver and a second ultrasonic transceiver, wherein the first ultrasonic transceiver and the second ultrasonic transceiver are respectively disposed on the outside of one closed end and the outside of the other closed end of the straight tube; A flow measurement device, the flow measurement device is used to measure the flow velocity flowing through the measuring tube body and calculate the flow rate of the fluid according to the measured flow velocity; as well as A signal processing device is used to make a first ultrasonic signal transmitted from the first ultrasonic transceiver and a second ultrasonic signal transmitted from the second ultrasonic transceiver pass through zero to maintain the same measurement point.

2. The flow measurement and correction system using ultrasonic waves according to claim 1, wherein: The first ultrasonic transceiver transmits the first ultrasonic signal to the second ultrasonic transceiver and receives the second ultrasonic signal transmitted by the second ultrasonic transceiver, and The second ultrasonic transceiver transmits the second ultrasonic signal to the first ultrasonic transceiver and receives the first ultrasonic signal transmitted by the first ultrasonic transceiver.

3. The flow measurement and correction system using ultrasonic waves according to claim 2, wherein: The flow measurement device comprises: a transducer that receives the first ultrasonic signal received by the second ultrasonic transceiver and the second ultrasonic signal received by the first ultrasonic transceiver, respectively, and generates digitized ultrasonic waveform data by making the received first ultrasonic signal and the second ultrasonic signal pass through zero, respectively; an FPGA IC that receives each ultrasonic waveform data from the transducer to calculate an arrival time of the first ultrasonic signal at the second ultrasonic transceiver and an arrival time of the second ultrasonic signal at the first ultrasonic transceiver, and measures a time difference between measured zero crossing points to generate time difference data; and a control unit, the control unit comparing a predetermined reference value K with a measured time difference between the measured zero-crossing points (An or Bn; A'n or B'n) of the first ultrasonic signal and the second ultrasonic signal, to take the first ultrasonic signal and the second ultrasonic signal when the measured time difference is within the range of the reference value K, calculate the flow velocity of the fluid by the measured moving time of the first ultrasonic signal from the first ultrasonic transceiver to the second ultrasonic transceiver and the moving time of the second ultrasonic signal from the second ultrasonic transceiver to the first ultrasonic transceiver, and calculate the flow rate of the fluid using the calculated fluid velocity, Wherein, the control unit is constructed as follows: Detect a change in the ultrasonic velocity of the fluid flowing through the horizontal pipe body, and eliminate flow measurement errors by correcting the measured transit times (tXY, tYX) of the first ultrasonic signal and the second ultrasonic signal using the ratio of the changed ultrasonic velocity to the ultrasonic velocity of the fluid set as a reference. The control unit calculates the ratio of the changed ultrasonic velocity to the ultrasonic velocity set as a reference, where the ratio is equal to the ultrasonic velocity set as a reference divided by the changed ultrasonic velocity, and corrects the transit times (tXY, tYX) of the first ultrasonic signal and the second ultrasonic signal measured by multiplying the transit time (tXY) of the first ultrasonic signal where an error occurs and the transit time (tYX) of the second ultrasonic signal by the reciprocal of the ratio of the ultrasonic velocity set as a reference to the changed ultrasonic velocity.

4. The flow measurement and correction system using ultrasonic waves according to claim 3, wherein: When the reference time difference between the measured zero crossings is referred to as TA0, the reference value K is in the range of 0.9TA0 < K < 1.1A0.

5. The flow measurement and correction system using ultrasonic waves according to claim 3, wherein: When taking both the measured zero crossings An, A’n of the first ultrasonic signal and the measured zero crossings Bn, B’n of the second ultrasonic signal, the measured zero crossing An - A’n is referred to as TAn, and the measured zero crossing Bn - B’n is referred to as TBn, false measurements are prevented by preferentially taking values that satisfy -α < TAn - TBn < +α, where α is an arbitrarily set value considering the flow rate of the measured pipe body.

6. The flow measurement and correction system using ultrasonic waves according to claim 1, wherein: The signal processing device includes: A detection unit that receives the first ultrasonic signal and the second ultrasonic signal through the first ultrasonic transceiver and the second ultrasonic transceiver to detect the first ultrasonic signal and the second ultrasonic signal transmitted from the first ultrasonic transceiver and the second ultrasonic transceiver; A conversion unit that includes an A / D converter, which samples the first ultrasonic signal and the second ultrasonic signal detected by the detection unit a predetermined number of times per cycle to detect the waveforms of the detected signals, and determines a first-cycle ultrasonic signal based on the detected waveforms of the first ultrasonic signal and the second ultrasonic signal; and A measurement unit that calculates the flow rate at a measurement point at a position moved through a set measurement cycle based on the first-cycle ultrasonic signal determined by the conversion unit, where the conversion unit samples signals for at least more cycles before and after the measurement point compared to the measurement cycle, and compares the sums of the sampled values for each cycle to determine the first-cycle ultrasonic signal.

7. The flow measurement and correction system using ultrasonic waves according to claim 6, wherein: The detection unit searches for and detects signals having the same frequency as the set transmission frequency of the first ultrasonic signal and the second ultrasonic signal.

8. The flow measurement and correction system using ultrasonic waves according to claim 6, wherein: When the sum of the sampled values for each cycle is equal to or greater than a set value, the conversion unit compares the sums of the sampled values for each cycle to determine the first-cycle ultrasonic signal, and When the sum of the sampling values ​​of each cycle continuously increases for three or more cycles, the conversion unit compares the sum of the sampling values ​​of each cycle to determine the first cycle ultrasonic signal.

9. The flow measurement and correction system using ultrasonic waves according to claim 6, wherein: The conversion unit further comprises an amplifying unit, which amplifies and adjusts the amplitude so that the sum of the sampling values ​​of each cycle is equal to a set standing wave value.

10. The flow measurement and correction system using ultrasonic waves according to claim 6, wherein: The conversion unit further includes a range unit which outputs the detected ultrasonic wave signal in real time based on the sampling value of each cycle.

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