An ultrasonic-based flow measurement method and system

Abstract

The present application discloses an ultrasonic-based flow measurement method and system, which transmits a first pulse signal; obtains the pulse signal received by a second ultrasonic chip, and determines a first time for the first pulse signal to reach the second ultrasonic chip from the first ultrasonic chip according to the time of transmitting the first pulse signal and the time of receiving the pulse signal; transmits a second pulse signal; obtains the pulse signal received by the first ultrasonic chip, and determines a second time for the second pulse signal to reach the first ultrasonic chip from the second ultrasonic chip according to the time of transmitting the second pulse signal and the time of the first ultrasonic chip receiving the pulse signal; and calculates the flow rate of the liquid. By means of the present application, the problem that the ultrasonic flowmeter in the prior art cannot meet the accuracy requirements is solved, thereby providing a method capable of measuring small flow rates and ensuring the measurement accuracy to a certain extent.

Description

Technical Field

[0001] This application relates to the field of flow measurement. Specifically, it relates to an ultrasonic-based flow measurement method and system. Background Art

[0002] Ultrasonic flowmeters in the prior art are generally applied to tap water or gas.

[0003] The general tap water flowmeter has a large market inventory. By means of the existing iron water pipes, two probes are installed obliquely and externally. The flowmeter in tap water cannot achieve high-precision small flow measurement.

[0004] Gas pipeline flowmeters such as gas ultrasonic flowmeters are similar to tap water ultrasonic flowmeters. They also rely on the original gas pipeline, and two or even more probes are installed obliquely and externally to complete ultrasonic measurement. The pipeline diameter is thick, the detection device is large in volume, and there are many probes, so small flow measurement cannot be achieved either.

[0005] Small flow meters are mainly applied to industries such as chip manufacturing, pharmaceuticals, and food processing to meet the design requirements of high-precision small flow, extremely low medium pollution, and small volume. The ultrasonic flowmeters in the prior art cannot meet the accuracy requirements. Summary of the Invention

[0006] The embodiments of this application provide an ultrasonic-based flow measurement method and system to at least solve the problem that the ultrasonic flowmeters in the prior art cannot meet the accuracy requirements.

[0007] According to one aspect of this application, an ultrasonic-based flow measurement method is provided, including: generating a first pulse signal and sending the first pulse signal at the ultrasonic frequency through a first ultrasonic chip; obtaining the pulse signal received by a second ultrasonic chip, and determining a first time for the first pulse signal to reach the second ultrasonic chip from the first ultrasonic chip according to the time of sending the first pulse signal and the time of receiving the pulse signal, wherein the propagation direction of the first pulse signal is the same as the liquid flow direction; generating a second pulse signal and sending the second pulse signal at the ultrasonic frequency through the second ultrasonic chip; obtaining the pulse signal received by the first ultrasonic chip, and determining a second time for the second pulse signal to reach the first ultrasonic chip from the second ultrasonic chip according to the time of sending the second pulse signal and the time of the first ultrasonic chip receiving the pulse signal, wherein the propagation direction of the second pulse signal is opposite to the liquid flow direction; calculating the flow rate of the liquid according to the first time, the second time, the distance between the first ultrasonic chip and the second ultrasonic chip, and the cross-sectional area of the pipeline where the liquid flows.

[0008] Further, obtaining the pulse signals received by the first ultrasonic chip and the second ultrasonic chip includes: receiving an echo signal, where the echo signal is a damped oscillating electrical signal; amplifying the echo signal; inputting the amplified echo signal into a comparator, comparing the echo signal with a bias voltage for comparison to obtain a second square wave signal, where the second square wave signal is used as the pulse signals received by the first ultrasonic chip and the second ultrasonic chip, and the pulse signal sent by the first ultrasonic chip or the second ultrasonic chip is a first square wave signal.

[0009] Further, after obtaining the second square wave signal by comparing the echo signal with the bias voltage for comparison, the method further includes: determining whether there is a ghost image in the second square wave signal, where the ghost image is a different square wave existing compared with the first square wave signal; eliminating the ghost image in the second square wave signal, and using the second square wave signal after eliminating the ghost image as the pulse signals received by the first ultrasonic chip and the second ultrasonic chip.

[0010] Further, determining whether there is a ghost image in the second square wave signal includes: obtaining the second square wave signals received twice; obtaining the moments of N consecutive rising edges in the second square wave signal received for the first time, where the 11th moment is the moment of the first rising edge, and so on, the 1Nth moment is the moment of the Nth rising edge; obtaining the moments of N consecutive rising edges in the second square wave signal received for the second time; where the 21st moment is the moment of the first rising edge, and so on, the 2Nth moment is the moment of the Nth rising edge; determining whether the difference between the 1Mth moment and the 2Mth moment is less than or equal to a threshold, if it is less than or equal to the threshold, it is determined that there is no ghost image in the second square wave signal, if it is greater than the threshold, it is determined that there is a ghost image in the second square wave signal, where M is a natural number greater than 1 and less than N.

[0011] Further, eliminating the ghost image in the second square wave signal includes: comparing the 1Mth moment with each moment from the 21st moment to the 2Nth moment; the moment closest to the 1Mth moment from the 21st moment to the 2Nth moment; updating the value of the 2Mth moment to the value of the closest moment for subsequent calculations.

[0012] According to another aspect of the present application, there is also provided an ultrasonic-based flow measurement system, including: a first generation module for generating a first pulse signal and transmitting the first pulse signal at the frequency of the ultrasonic wave through a first ultrasonic wave sheet; a first acquisition module for acquiring the pulse signal received by a second ultrasonic wave sheet, and determining a first time for the first pulse signal to reach the second ultrasonic wave sheet from the first ultrasonic wave sheet according to the time of transmitting the first pulse signal and the time of receiving the pulse signal, wherein the propagation direction of the first pulse signal is the same as the liquid flow direction; a second generation module for generating a second pulse signal and transmitting the second pulse signal at the frequency of the ultrasonic wave through the second ultrasonic wave sheet; a second acquisition module for acquiring the pulse signal received by the first ultrasonic wave sheet, and determining a second time for the second pulse signal to reach the first ultrasonic wave sheet from the second ultrasonic wave sheet according to the time of transmitting the second pulse signal and the time of the first ultrasonic wave sheet receiving the pulse signal, wherein the propagation direction of the second pulse signal is opposite to the liquid flow direction; a calculation module for calculating the flow rate of the liquid according to the first time, the second time, the distance between the first ultrasonic wave sheet and the second ultrasonic wave sheet, and the cross-sectional area of the pipe where the liquid flows.

[0013] Further, the first acquisition module and the second acquisition module are configured to: receive an echo signal, where the echo signal is a damped oscillating electrical signal; amplify the echo signal; input the amplified echo signal into a comparator, and compare the echo signal with a bias voltage for comparison to obtain a second square wave signal, where the second square wave signal is used as the pulse signal received by the first ultrasonic wave sheet and the second ultrasonic wave sheet, and the pulse signal transmitted by the first ultrasonic wave sheet or the second ultrasonic wave sheet is a first square wave signal.

[0014] Further, the first acquisition module and the second acquisition module are configured to: determine whether there is a ghost image in the second square wave signal, where the ghost image is a different square wave compared with the first square wave signal and the second square wave signal; eliminate the ghost image in the second square wave signal, and use the second square wave signal after eliminating the ghost image as the pulse signal received by the first ultrasonic wave sheet and the second ultrasonic wave sheet.

[0015] Further, the first acquisition module and the second acquisition module are used to: acquire the second square wave signal received twice; acquire the moments of N consecutive rising edges in the second square wave signal received for the first time, wherein the 11th moment is the moment of the first rising edge, and so on, the 1Nth moment is the moment of the Nth rising edge; acquire the moments of N consecutive rising edges in the second square wave signal received for the second time, wherein the 21st moment is the moment of the first rising edge, and so on, the 2Nth moment is the moment of the Nth rising edge; determine whether the difference between the 1Mth moment and the 2Mth moment is less than or equal to a threshold, if it is less than or equal to the threshold, determine that there is no ghost in the second square wave signal, and if it is greater than the threshold, determine that there is a ghost in the second square wave signal, wherein M is a natural number greater than 1 and less than N.

[0016] Furthermore, the first acquisition module and the second acquisition module are used to: compare the 1Mth moment with each moment from the 21st moment to the 2Nth moment; the moment closest to the 1Mth moment from the 21st moment to the 2Nth moment; update the value of the 2Mth moment to the value of the closest moment, and use it for subsequent calculations.

[0017] In the embodiment of the present application, a first pulse signal is generated, and the first pulse signal is sent by the first ultrasonic blade using the frequency of the ultrasonic wave; the pulse signal received by the second ultrasonic blade is obtained, and the first time when the first pulse signal arrives at the second ultrasonic blade from the first ultrasonic blade is determined according to the time when the first pulse signal is sent and the time when the pulse signal is received, wherein the propagation direction of the first pulse signal is the same as the flow direction of the liquid; a second pulse signal is generated, and the second pulse signal is sent by the second ultrasonic blade using the frequency of the ultrasonic wave; the pulse signal received by the first ultrasonic blade is obtained, and the second time when the second pulse signal arrives at the first ultrasonic blade from the second ultrasonic blade is determined according to the time when the second pulse signal is sent and the time when the first ultrasonic blade receives the pulse signal, wherein the propagation direction of the second pulse signal is opposite to the flow direction of the liquid; the flow rate of the liquid is calculated according to the first time, the second time, the distance between the first ultrasonic blade and the second ultrasonic blade, and the cross-sectional area of the pipe where the liquid flows. The present application solves the problem that the ultrasonic flowmeter in the prior art cannot meet the accuracy requirements, thereby providing a method that can measure small flow rates and ensures the accuracy of the measurement to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 It is a schematic diagram of an ultrasonic pipeline design according to an embodiment of the present application.

[0020] Figure 2 It is a schematic diagram of the ultrasonic plate structure arrangement according to an embodiment of the present application.

[0021] Figure 3 is a schematic diagram of an alternating driving circuit according to an embodiment of the present application.

[0022] Figure 4 It is a schematic diagram of the principle of the amplification and shaping circuit according to an embodiment of the present application.

[0023] Figure 5 It is a schematic diagram of the operating waveform of the shaping amplifier circuit according to an embodiment of the present application.

[0024] Figure 6 It is a schematic diagram of the cause of ghosting according to an embodiment of the present application.

[0025] Figure 7 It is a flowchart of a ghost processing algorithm according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0028] In this embodiment, the direction of ultrasonic wave propagation is the same as or opposite to the direction of liquid flow. Under this condition, there can be a variety of pipeline designs, one of which is provided in this embodiment.

[0029] Figure 1 is a schematic diagram of an ultrasonic pipeline design according to an embodiment of the present application, such as Figure 1 As shown, the ultrasonic pipeline includes two ultrasonic sheets 1, which are coupled to the pipeline 3 through a coupling agent 2. The pipeline 3 can be a deionized PFA material pipeline. The two ultrasonic sheets 1 can be a PZT ultrasonic piezoelectric ceramic sheet A and a PZT ultrasonic piezoelectric ceramic sheet B.

[0030] Figure 1 As shown, it is a U-shaped pipe with the inlet and outlet on the same side. It can also be a Z-shaped pipe with the inlet and outlet arranged on both sides. The pipe type is selected according to the actual installation requirements of the ultrasonic flowmeter.

[0031] There is a flowing measured liquid in the pipe. The ultrasonic piezoelectric ceramic chips A and B work in pairs and are tightly attached to the end faces on both sides of the pipe through a coupling agent, with the center lines of the ceramic chips installed coincidentally. When A is the transmitter and B is the receiver, the ultrasonic propagation speed is the value obtained by adding the flow velocity to the speed of sound; when A is the receiver and B is the transmitter, the ultrasonic propagation speed is the value obtained by subtracting the flow velocity from the speed of sound. Subtracting the results obtained twice before and after commutation and removing the speed of sound, the obtained result is proportional to the flow velocity.

[0032] The process of calculating the flow rate of the measured liquid is as follows:

[0033] The distance between the two PZTs is L, the forward flight time is T1, the reverse flight time is T2, and the pipe diameter is D. Assume T1>T2, where,

[0034]

[0035]

[0036] V1 = V 声速 + V 流速

[0037] V2 = V 声速 - V 流速

[0038]

[0039]

[0040] Due to the characteristics of PFA plastic, the loss of ultrasonic transmission is relatively large. It is necessary to use a special piezoelectric ceramic chip with a characteristic frequency of 2 MHz for the ultrasonic flowmeter as the transmitting and receiving elements. Since this type of piezoelectric ceramic chip is relatively brittle, in order to reliably press the ceramic chip on the cross-section, keep it centered, and be able to lead out the signal, the structure provided in this embodiment is Figure 2 as follows.

[0041] In Figure 2 the structure shown includes: an ultrasonic piezoelectric ceramic chip 1, a pipeline 3 at the liquid outlet, an end face 5, a positioning frame (shown as a cross-section in the figure) 4, a sheath cable 6, a cable outlet 7, a pressing piece 8, a rear cover 9, and a cavity 10. As Figure 2 shown, the center lines of components such as the pipeline, piezoelectric ceramic chip, positioning frame, pressing piece, cavity, and rear cover coincide.

[0042] The inner diameter of the pipeline can be 4mm, 6mm, 8mm, etc., not limited to the above dimensions. Ultrasonic coupling agent is applied to the contact area between the end face and the piezoelectric ceramic. The positioning frame is a hollow annular plastic component with an outer diameter equal to the inner diameter of the cavity and an inner diameter equal to the outer diameter of the ultrasonic piezoelectric ceramic sheet. The height should be lower than the thickness of the piezoelectric sheet. After being installed in the cavity, it does not contact the pressing sheet to prevent the failure of the pressing sheet's function of pressing the ceramic sheet. The pressing sheet is also made of plastic. A channel for the lead-out of the wire is reserved on the pressing sheet, which contacts the back cover. There is a notch on the outside of the back cover for easy clamping. The back cover and the cavity are connected by threads. After tightening the back cover, the piezoelectric ceramic sheet is reliably crimped on the end face. The piezoelectric ceramic signal lead-out wire is a sheathed wire with a sheath diameter equal to the diameter of the outlet hole. After tightening the back cover, the cavity has a splash-proof function.

[0043] Based on the ultrasonic flowmeter in this embodiment, an ultrasonic flow measurement method is provided in this embodiment, and the steps in the method are described below.

[0044] Step S10, generating a first pulse signal, and sending the first pulse signal at an ultrasonic frequency through a first ultrasonic wave sheet;

[0045] Step S20, obtaining the pulse signal received by the second ultrasonic blade, and determining the first time when the first pulse signal arrives at the second ultrasonic blade from the first ultrasonic blade according to the time when the first pulse signal is sent and the time when the pulse signal is received, wherein the propagation direction of the first pulse signal is the same as the flow direction of the liquid;

[0046] Step S30, generating a second pulse signal, and sending the second pulse signal at the frequency of the ultrasound through the second ultrasound blade;

[0047] Step S40, obtaining the pulse signal received by the first ultrasonic blade, and determining a second time when the second pulse signal reaches the first ultrasonic blade from the second ultrasonic blade according to the time when the second pulse signal is sent and the time when the first ultrasonic blade receives the pulse signal, wherein the propagation direction of the second pulse signal is opposite to the flow direction of the liquid;

[0048] Step S50, calculating the flow rate of the liquid according to the first time, the second time, the distance between the first ultrasonic blade and the second ultrasonic blade, and the cross-sectional area of the pipe where the liquid flows.

[0049] In the above steps, the flight time of ultrasonic waves is obtained based on the pulse signal. Considering that the propagation direction of ultrasonic waves is the same as or opposite to the liquid flow direction, this method of measuring the flight time is relatively accurate. Therefore, the problem that the ultrasonic flowmeter in the prior art cannot meet the accuracy requirements is solved by the method in this embodiment, thereby providing a method capable of measuring small flow rates and ensuring the measurement accuracy to a certain extent.

[0050] In the above method, the transmission and reception between the first ultrasonic chip and the second ultrasonic chip need to be switched. In this embodiment, an alternating drive circuit is provided. Figure 3 It is a schematic diagram of the alternating drive circuit according to an embodiment of the present application, as Figure 3 shown. In this circuit, the alternating drive circuit is mainly responsible for transmitting the pulse signal output by the power amplifier to the corresponding ultrasonic piezoelectric ceramic chip, and connecting the other ultrasonic piezoelectric ceramic chip opposite thereto to the receiving circuit. The specific switching process is as follows:

[0051] The logic circuit controls the analog switch to connect PZTA to the power amplifier, and controls the pulse generator to output a transmission pulse sequence to the power amplifier. At this time, the analog switch connects PZTB to the receiving circuit and waits for the arrival of the echo. After the echo arrives, the flight time is calculated and analyzed by the logic circuit.

[0052] After the above process, a working process of PZTA transmitting and PZTB receiving is completed. The next step is to perform a flip switch: similar to the above process, the logic circuit controls the analog switch to connect PZTB to the power amplifier, and controls the pulse generator to output a transmission pulse sequence to the power amplifier. At this time, the analog switch connects PZTA to the receiving circuit and waits for the arrival of the echo. After the echo arrives, the flight time is calculated and analyzed by the logic circuit. Thus, a switching process is completed. This ultrasonic flowmeter will repeat the above steps for continuous measurement.

[0053] The received pulse signal may be relatively weak. To ensure accurate measurement, a signal amplification function can also be added. That is, obtaining the pulse signals received by the first ultrasonic chip and the second ultrasonic chip may include: receiving an echo signal, where the echo signal is a damped oscillation electrical signal; amplifying the echo signal; inputting the amplified echo signal into a comparator, comparing the echo signal with a bias voltage for comparison to obtain a second square wave signal, where the second square wave signal is used as the pulse signal received by the first ultrasonic chip and the second ultrasonic chip, and the pulse signal sent by the first ultrasonic chip or the second ultrasonic chip is a first square wave signal.

[0054] In the above steps, a shaping and amplification circuit is involved. The main function of the shaping and amplification circuit is to controllably amplify and shape the weak electrical signal generated by the received piezoelectric ceramic sheet, and finally output a square wave sequence, so as to facilitate the ultrasonic flowmeter logic circuit to calculate and analyze the flight time. The ultrasonic echo signal is extremely weak and accompanied by interference, and the signal needs to be amplified and shaped in a specific time period. Figure 4 is a schematic diagram of the principle of the shaping and amplification circuit according to an embodiment of the present application. As Figure 4 shown, the input echo signal is a weak damped oscillation electrical signal. After passing through the programmable switch, it can selectively allow the signal in a specific time period to pass through to the subsequent circuit. For the weak echo signal, an LNA (low noise amplifier) circuit is required. This part of the circuit is constructed using a low-noise and high-bandwidth integrated operational amplifier, or an on-chip LNA amplifier of a dedicated ultrasonic front-end analog circuit chip can also be used, and it is not limited to one type of amplifier. After the signal is amplified by the LNA, it is sent to a programmable gain amplifier circuit (PGA) for further amplification. This part can be programmed for the amplification factor according to the control strategy of the logic circuit, and the amplification factor range is 0 to 21 dB. At this time, the signal amplitude is greatly increased, and it is sent to a comparator as one input signal of the comparator for comparison processing. The other input signal of the comparator is generated by a programmable reference voltage source and serves as a comparison bias voltage. The reference 0 potential of this bias voltage is determined by the average voltage in a period of time before the echo signal arrives. The voltage value of this voltage source can be adjusted according to actual needs to achieve a better comparison effect and output a stable square wave sequence to the subsequent arithmetic processing circuit.

[0055] For the output square wave sequence, Figure 5 is a schematic diagram of the working waveform of the shaping and amplification circuit according to an embodiment of the present application. As Figure 5 shown, this figure shows: a noise interference signal 51, a place 52 where the reference 0 potential of the comparator bias voltage is obtained, the comparator bias voltage 53, the echo damped electrical signal 54, and the comparator output square wave sequence 55.

[0056] The working principle is as described in the circuit introduction above. Since the length of the measuring pipeline is fixed when the ultrasonic flowmeter is designed, the time from the sound emission to the reception is relatively certain under the premise that the sound velocity does not change dramatically. Ignoring the minute difference caused by the flow velocity change, the echo always appears on the receiving piezoelectric ceramic at a specific time, and there will be no large displacement on the time axis. The signal processing can be carried out according to a set of predetermined control timings, and each echo amplification and shaping is divided into A, B, and C areas. In area A, the programmable switch is turned off, and the interference signal outside the effective range of the echo can be ignored; multiple sampling and averaging are performed in the next area B to obtain a relatively stable level, which can effectively represent the 0-point potential of the echo signal. This potential and the programmable reference power supply jointly generate the bias voltage required by the comparator. When the amplified echo signal is transmitted to the comparator, the signal exceeding the bias voltage outputs a square wave high level after the next reverse zero crossing, and outputs a low level after the forward zero crossing. This operation generates a square wave signal consistent with the phase of the echo damping oscillation signal, which is processed and analyzed by the subsequent logic circuit.

[0057] In this embodiment, the detection software can be used for processing. The detection software runs on an embedded microprocessor and controls other components through an auxiliary logic circuit to complete the acquisition and calculation of the ultrasonic flowmeter. Like a general ultrasonic flowmeter, the ultrasonic flowmeter described in this method also includes functions such as flight time calculation, flow conversion and alarm output. However, due to the attenuation of the signal by the FPA material pipeline, the echo signal is weak. After the above-mentioned high-magnification amplification, the echo signal has a problem of poor amplitude stability. The square wave sequence signal may have a ghosting phenomenon after shaping, resulting in serious deviations in the flight time calculation.

[0058] Figure 6 Schematic diagram of the cause of ghosting according to an embodiment of the application, such as Figure 6 As shown, when the echo damping oscillation signal is amplified, jitter is inevitable. When the comparator bias voltage is set, the output square wave sequence changes. In the figure above, 61 is a signal with increased amplitude, and 62 is a signal with unchanged amplitude. The square wave sequences generated after the two signal amplification and shaping are 63 and 64 respectively. It can be seen that there is a clear difference between 63 and 64. 64 has two more square wave signals than 63, as indicated by 65, which is a virtual shadow, which is obvious when observed on the oscilloscope.

[0059] For simplicity, the 63 signal is treated as a square wave sequence, and only two square waves are plotted. In practice, there may be about five square wave sequences, but the number is not limited to this.

[0060] That is, in this embodiment, it is also possible to determine whether there is a ghost image. After comparing the echo signal with a bias voltage for comparison to obtain a second square wave signal, the method further includes: determining whether there is a ghost image in the second square wave signal, where the ghost image is a different square wave existing when the first square wave signal is compared with the second square wave signal; eliminating the ghost image in the second square wave signal, and using the second square wave signal after eliminating the ghost image as the pulse signal received by the first ultrasonic chip and the second ultrasonic chip.

[0061] There are many ways to determine whether there is a ghost image. For example, determining whether there is a ghost image in the second square wave signal includes: obtaining the second square wave signals received twice; obtaining the moments of N consecutive rising edges in the second square wave signal received for the first time, where the 11th moment is the moment of the first rising edge, and so on, the 1Nth moment is the moment of the Nth rising edge; obtaining the moments of N consecutive rising edges in the second square wave signal received for the second time; where the 21st moment is the moment of the first rising edge, and so on, the 2Nth moment is the moment of the Nth rising edge; determining whether the difference between the 1Mth moment and the 2Mth moment is less than or equal to a threshold. If it is less than or equal to the threshold, it is determined that there is no ghost image in the second square wave signal. If it is greater than the threshold, it is determined that there is a ghost image in the second square wave signal, where M is a natural number greater than 1 and less than N.

[0062] There are also many ways to eliminate the ghost image. For example, eliminating the ghost image in the second square wave signal includes: comparing the 1Mth moment with each moment from the 21st moment to the 2Nth moment; finding the moment closest to the 1Mth moment from the 21st moment to the 2Nth moment; updating the value of the 2Mth moment to the value of the closest moment and using it for subsequent calculations.

[0063] The above algorithm will be described below with reference to the accompanying drawings. Figure 7 is a flowchart of the ghost image processing algorithm according to an embodiment of the present application. As Figure 7 shown, when a square wave sequence is received, the logic circuit calculates the time when several square waves in the sequence appear after the transmission pulse, obtains the rising edge moments of each square wave, the first rising edge is denoted as T1, the second rising edge is denoted as T2, and so on. Generally, obtaining about 5 square wave rising edge times can complete the algorithm, and store these moment values T1 to T5.

[0064] Relative to the first square wave sequence, the second square wave sequence is received, and the calculation similar to the above process is performed to obtain the T1~T5 values. Taking 5 square wave sequences as an example, T3 is used as a typical value, and the T3 of the second square wave sequence is compared with the T3 value stored last time. If it is found that the change is very small, it is a normal test process, and no ghost image occurs, and the cycle is repeated; if it is found that the T3 value changes greatly, it is compared from the second square wave sequence T1~T5 to determine which value is close to the T3 collected last time, and then updated to the T3 value of this measurement. The updated T3 value is used for subsequent calculations to remove the influence of ghost images on the flight time.

[0065] By obtaining the accurate flight time, accurate flow calculation can be performed, and other additional functions of the flow meter can be completed, such as flow result transmission, high and low flow alarms, etc.

[0066] In the above embodiment, the following timing module can be used for timing. The flight time calculation module, that is, the picosecond timing module, can convert the flight time (picosecond level) into a digital quantity. The conversion process is as follows: the module is connected to an 8MHz active crystal oscillator to provide a clock reference. After each power-on, the module automatically completes the timing calibration of 10 clock cycles (duration 1 / 8uS*10=1.25uS) to obtain the precise time value of the minimum timing unit. For example, within 10 clock cycles, the timer value is 10000, then the minimum timing unit is 1.25uS / 10000=125pS. When the picosecond timing module obtains the start signal (rising edge is valid), it starts counting and accumulating, and stops counting and accumulating after obtaining the stop signal (rising edge is valid). The count value*125pS is the flight time.

[0067] In this embodiment, an electronic device is provided, including a memory and a processor. The memory stores a computer program, and the processor is configured to run the computer program to execute the method in the above embodiment.

[0068] The above program can run in a processor or can also be stored in a memory (or referred to as a computer-readable medium). A computer-readable medium includes permanent and non-permanent, removable and non-removable media and can implement information storage by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic tape disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information accessible by a computing device. As defined herein, a computer-readable medium does not include transitory computer-readable media such as modulated data signals and carrier waves.

[0069] These computer programs can also be loaded onto a computer or other programmable data processing device so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one process or multiple processes and / or Figure 1 boxes. The steps corresponding to different steps can be implemented by different modules.

[0070] In this embodiment, such a device or system is provided. The system is called an ultrasonic-based flow measurement system, including: a first generation module for generating a first pulse signal and transmitting the first pulse signal at the frequency of ultrasonic waves through a first ultrasonic chip; a first acquisition module for acquiring the pulse signal received by a second ultrasonic chip and determining a first time for the first pulse signal to reach the second ultrasonic chip from the first ultrasonic chip according to the time of transmitting the first pulse signal and the time of receiving the pulse signal, wherein the propagation direction of the first pulse signal is the same as the liquid flow direction; a second generation module for generating a second pulse signal and transmitting the second pulse signal at the frequency of ultrasonic waves through the second ultrasonic chip; a second acquisition module for acquiring the pulse signal received by the first ultrasonic chip and determining a second time for the second pulse signal to reach the first ultrasonic chip from the second ultrasonic chip according to the time of transmitting the second pulse signal and the time of the first ultrasonic chip receiving the pulse signal, wherein the propagation direction of the second pulse signal is opposite to the liquid flow direction; a calculation module for calculating the flow rate of the liquid according to the first time, the second time, the distance between the first ultrasonic chip and the second ultrasonic chip, and the cross-sectional area of the pipeline where the liquid flows.

[0071] The system or device is used to implement the functions of the method in the above embodiment. Each module in the system or device corresponds to each step in the method, and those that have been described in the method will not be elaborated here.

[0072] For example, the first acquisition module and the second acquisition module are used to: receive an echo signal, where the echo signal is a damped oscillation electrical signal; amplify the echo signal; input the amplified echo signal into a comparator and compare the echo signal with a bias voltage for comparison to obtain a second square wave signal, where the second square wave signal is used as the pulse signal received by the first ultrasonic chip and the second ultrasonic chip, and the pulse signal transmitted by the first ultrasonic chip or the second ultrasonic chip is a first square wave signal.

[0073] For another example, the first acquisition module and the second acquisition module are used to: determine whether there is a ghost image in the second square wave signal, where the ghost image is a different square wave compared with the first square wave signal and the second square wave signal; eliminate the ghost image in the second square wave signal and use the second square wave signal after eliminating the ghost image as the pulse signal received by the first ultrasonic chip and the second ultrasonic chip.

[0074] Optionally, the first acquisition module and the second acquisition module are used to: acquire the second square wave signal received twice; acquire the moments of N consecutive rising edges in the second square wave signal received for the first time, wherein the 11th moment is the moment of the first rising edge, and so on, the 1Nth moment is the moment of the Nth rising edge; acquire the moments of N consecutive rising edges in the second square wave signal received for the second time, wherein the 21st moment is the moment of the first rising edge, and so on, the 2Nth moment is the moment of the Nth rising edge; determine whether the difference between the 1Mth moment and the 2Mth moment is less than or equal to a threshold, if it is less than or equal to the threshold, it is determined that there is no ghost in the second square wave signal, and if it is greater than the threshold, it is determined that there is a ghost in the second square wave signal, wherein M is a natural number greater than 1 and less than N.

[0075] Optionally, the first acquisition module and the second acquisition module are used to: compare the 1Mth moment with each moment from the 21st moment to the 2Nth moment; the moment closest to the 1Mth moment from the 21st moment to the 2Nth moment; update the value of the 2Mth moment to the value of the closest moment, and use it for subsequent calculations.

[0076] The above-mentioned embodiments solve the problem that the ultrasonic flowmeter in the prior art cannot meet the accuracy requirement, thereby providing a device capable of measuring small flow rates and ensuring the measurement accuracy to a certain extent.

[0077] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. An ultrasonic-based flow measurement method, characterized in that, include: Generate a first pulse signal, and send the first pulse signal at an ultrasonic frequency through a first ultrasonic wave sheet; Acquire the pulse signal received by the second ultrasonic blade, and determine the first time when the first pulse signal arrives at the second ultrasonic blade from the first ultrasonic blade according to the time when the first pulse signal is sent and the time when the pulse signal is received, wherein the propagation direction of the first pulse signal is the same as the flow direction of the liquid; generating a second pulse signal, and transmitting the second pulse signal at the frequency of the ultrasonic wave through the second ultrasonic wave blade; Acquire the pulse signal received by the first ultrasonic blade, and determine the second time when the second pulse signal reaches the first ultrasonic blade from the second ultrasonic blade according to the time when the second pulse signal is sent and the time when the first ultrasonic blade receives the pulse signal, wherein the propagation direction of the second pulse signal is opposite to the flow direction of the liquid; wherein acquiring the pulse signal received by the first ultrasonic blade and the second ultrasonic blade comprises: receiving an echo signal, wherein the echo signal is a damped oscillation electrical signal; amplifying the echo signal; inputting the amplified echo signal into a comparator, and comparing the echo signal with a bias voltage for comparison to obtain a second square wave signal, wherein the second square wave signal is the pulse signal received by the first ultrasonic blade and the second ultrasonic blade, and the pulse signal sent by the first ultrasonic blade or the second ultrasonic blade is the first square wave signal; Calculating the flow rate of the liquid according to the first time, the second time, the distance between the first ultrasonic blade and the second ultrasonic blade, and the cross-sectional area of the pipe where the liquid flows; Determine whether there is a ghost in the second square wave signal, wherein the ghost is a different square wave between the first square wave signal and the second square wave signal; wherein, obtain the second square wave signal received twice; obtain the moments of N consecutive rising edges in the second square wave signal received for the first time, wherein the 11th moment is the moment of the first rising edge, and so on, the 1Nth moment is the moment of the Nth rising edge; obtain the moments of N consecutive rising edges in the second square wave signal received for the second time; wherein the 21st moment is the moment of the first rising edge, and so on, the 2Nth moment is The moment of the Nth rising edge; determine whether the difference between the 1Mth moment and the 2Mth moment is less than or equal to a threshold, if it is less than or equal to the threshold, determine that there is no ghost in the second square wave signal, if it is greater than the threshold, determine that there is a ghost in the second square wave signal, wherein M is a natural number greater than 1 and less than N, wherein the difference is the difference between the amplitudes of the square wave rising edges at the 1Mth moment and the 2Mth moment; eliminate the ghost in the second square wave signal, and use the second square wave signal after eliminating the ghost as the pulse signal received by the first ultrasonic blade and the second ultrasonic blade.

2. The method according to claim 1, wherein Eliminating the ghost in the second square wave signal includes: Compare the 1M-th moment with each moment from the 21-st moment to the 2N-th moment; The moment closest to the 1M-th moment from the 21-st moment to the 2N-th moment; Update the value of the 2M-th moment to the value of the closest moment and use it for subsequent calculations.

3. An ultrasonic-based flow measurement system, characterized in that, Comprising: A first generation module for generating a first pulse signal and transmitting the first pulse signal at the ultrasonic frequency through a first ultrasonic wafer; A first acquisition module for acquiring the pulse signal received by a second ultrasonic wafer, and determining a first time for the first pulse signal to reach the second ultrasonic wafer from the first ultrasonic wafer according to the time of transmitting the first pulse signal and the time of receiving the pulse signal, wherein the propagation direction of the first pulse signal is the same as the liquid flow direction; A second generation module for generating a second pulse signal and transmitting the second pulse signal at the ultrasonic frequency through the second ultrasonic wafer; A second acquisition module for acquiring the pulse signal received by the first ultrasonic wafer, and determining a second time for the second pulse signal to reach the first ultrasonic wafer from the second ultrasonic wafer according to the time of transmitting the second pulse signal and the time of the first ultrasonic wafer receiving the pulse signal, wherein the propagation direction of the second pulse signal is opposite to the liquid flow direction; A calculation module for calculating the flow rate of the liquid according to the first time, the second time, the distance between the first ultrasonic wafer and the second ultrasonic wafer, and the cross-sectional area of the pipeline where the liquid flows; Wherein, the first acquisition module and the second acquisition module are used to: receive an echo signal, wherein the echo signal is a damped oscillation electrical signal; amplify the echo signal; input the amplified echo signal into a comparator, compare the echo signal with a bias voltage for comparison to obtain a second square wave signal, wherein the second square wave signal is a pulse signal received by the first ultrasonic chip and the second ultrasonic chip, and the pulse signal sent by the first ultrasonic chip or the second ultrasonic chip is the first square wave signal; determine whether there is a ghost in the second square wave signal, wherein the ghost is a different square wave between the first square wave signal and the second square wave signal; wherein the second square wave signal received twice is acquired; the moments of N consecutive rising edges in the second square wave signal received for the first time are acquired, wherein the 11th moment is the moment of the first rising edge, and so on, the 1Nth moment is the moment of the Nth rising edge; obtain the moments of N consecutive rising edges in the second square wave signal received for the second time; wherein, the 21st moment is the moment of the first rising edge, and so on, the 2Nth moment is the moment of the Nth rising edge; determine whether the difference between the 1Mth moment and the 2Mth moment is less than or equal to a threshold, if it is less than or equal to the threshold, determine that there is no ghost in the second square wave signal, if it is greater than the threshold, determine that there is a ghost in the second square wave signal, wherein M is a natural number greater than 1 and less than N, wherein the difference is the difference between the amplitudes of the square wave rising edges at the 1Mth moment and the 2Mth moment; eliminate the ghost in the second square wave signal, and use the second square wave signal after eliminating the ghost as the pulse signal received by the first ultrasonic blade and the second ultrasonic blade.

4. The system according to claim 3, wherein The first acquisition module and the second acquisition module are used for: Compare the 1Mth moment with each moment from the 21st moment to the 2Nth moment; From the 21st moment to the moment closest to the 1Mth moment among the 2N moments; The value at the 2Mth moment is updated to the value at the closest moment and used for subsequent calculations.

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