Ultrasonic flow measuring device and control method

Abstract

The present invention discloses an ultrasonic flow measurement device and control method, comprising an ultrasonic signal control module, an asynchronous integral time difference and phase difference measurement module, a flow rate measurement module, a reference pulse generation module, and a downstream ultrasonic transducer and a reverse ultrasonic transducer installed in a fluid pipeline wall mounting seat; the input / output ends of the downstream ultrasonic transducer and the reverse ultrasonic transducer are both connected to the output / input end of the ultrasonic signal control module, the output end of the ultrasonic signal control module is connected to the input end of the asynchronous integral time difference and phase difference measurement module, and the output end of the asynchronous integral time difference and phase difference measurement module is connected to the input end of the flow rate measurement module; the output end of the reference pulse generation circuit is respectively connected to the input end of the ultrasonic signal control module and the asynchronous integral time difference and phase difference measurement module. The present invention solves the problems of large flow rate measurement with a downstream and reverse flow phase difference exceeding one cycle and small amplitude of the first wave received by the time difference method.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic flow measurement, and in particular to an ultrasonic flow measurement device and a control method. Background Art

[0002] Compared with traditional measurement technology, ultrasonic flow measurement technology has the advantages of high measurement accuracy, wide range ratio, and low wear, and has gradually become the mainstream technology in the field of flow measurement. Ultrasonic flow measurement technology includes a variety of methods, such as time difference method, frequency difference method, phase difference method, Doppler method, beam offset method and noise method. The flow measurement methods generally used in closed pipelines include time difference method, phase difference method and dedicated chip ultrasonic flow measurement method.

[0003] The time difference method uses the time difference when sound waves propagate the same distance in the fluid downstream and upstream. The flow velocity of the measured fluid is related to the difference in propagation time. By measuring the time difference, the velocity of the fluid can be obtained. When the pipeline fluid is stationary, the ultrasonic time transmitted by the upstream and downstream ultrasonic waves is equal. When the fluid flows, under the action of the fluid, the ultrasonic transmission time of the upstream is slower than that of the downstream, thus generating a time difference. The faster the flow rate, the greater the time difference. In actual measurement applications, ultrasonic waves are sent in the form of pulses through an electronic transceiver circuit, and the transit time from the send to the receiver is recorded through a processing circuit. The transit time is amplified by an amplifier circuit unit and then sent to a single-chip microcomputer. The single-chip microcomputer calculates the velocity and flow of the pipeline fluid through program software. The defects of this method are: first, the transit time from the send to the receive needs to be amplified, but due to the limitation of the integrated circuit technology level, the amplification factor of the amplifier circuit cannot meet the requirements of the transit time amplification factor, resulting in low flow measurement resolution. Second, the time difference method requires capturing the first received waveform, but the amplitude of the first received waveform is very small, which affects the stability of flow measurement.

[0004] The phase difference method is to obtain the phase difference between the upstream and downstream by the phase difference between the received upstream ultrasonic pulse and the standard time-scale pulse, and the phase difference between the received downstream ultrasonic pulse and the standard time-scale pulse. The flow rate of the measured fluid is positively correlated with the phase difference. The phase difference is processed by the electronic shaping and widening circuit, and the phase difference is converted into a modulated pulse width proportional to the flow rate, and then sent to the single-chip copper drum program software to calculate the flow rate and flow of the pipeline fluid. The defects of this method are: first, because in actual measurement, the phase difference cannot exceed one cycle, the flow rate of the measured fluid cannot be too large, which increases the difficulty of designing the pipeline flow measurement cavity structure. Second, the phase difference method requires temperature compensation, which increases the hardware design cost, and it is impossible to perform temperature compensation in real time, which reduces the accuracy of flow measurement.

[0005] The dedicated chip ultrasonic flow measurement method uses the gate transmission delay inside the chip to achieve tiny time measurement, and uses the absolute time difference between the upstream and downstream to calculate the fluid flow rate. The defects of this method are: first, it is necessary to capture the first ultrasonic receiving pulse as a reference. Since the amplitude of the first ultrasonic waveform received is very small, the stability of the flow measurement is poor. Second, the ultrasonic transceiver signal processing is completed inside the dedicated chip. The impedance matching and signal shaping of the transceiver transducer cannot adapt to different working conditions, resulting in excessive upstream and downstream time difference and instability when the pipeline fluid is stationary, which leads to poor stability of the flow measurement. Third, since the amplification factor of the upstream and downstream time difference is fixed, it cannot meet the measurement accuracy of flows of different calibers, especially in applications with small time difference of small calibers. Summary of the invention

[0006] The object of the present invention is to provide an ultrasonic flow measuring device and a control method to improve the reliability of ultrasonic flow measurement.

[0007] To achieve the above objectives, the present invention adopts an ultrasonic flow measurement device, which includes an ultrasonic signal control module, an asynchronous integral time difference and phase difference measurement module, a flow rate measurement module, a reference pulse generation module, and a downstream ultrasonic transducer and a reverse ultrasonic transducer installed in a fluid pipeline wall mounting seat;

[0008] The input / output ends of the downstream ultrasonic transducer and the upstream ultrasonic transducer are both connected to the output / input ends of the ultrasonic signal control module, the output end of the ultrasonic signal control module is also connected to the input end of the asynchronous integral time difference and phase difference measurement module, and the output end of the asynchronous integral time difference and phase difference measurement module is connected to the input end of the flow rate measurement module;

[0009] The output end of the reference pulse generating circuit is respectively connected with the input end of the ultrasonic signal control module, the asynchronous integral time difference and phase difference measuring module and the flow rate measuring module.

[0010] Preferably, the ultrasonic signal control module includes a signal channel switching circuit, a bandpass frequency selection amplification circuit and a digital pulse forming circuit;

[0011] The input end of the signal channel switching circuit is respectively connected to the trigger pulse control circuit, the output end of the downstream ultrasonic transducer and the upstream ultrasonic transducer, and the output end is connected to the bandpass frequency selection amplifier circuit, the input end of the downstream ultrasonic transducer and the upstream ultrasonic transducer;

[0012] The output end of the bandpass frequency selection amplifier circuit is connected to the input end of the digital pulse forming circuit.

[0013] Preferably, the asynchronous integral time difference and phase difference measurement module comprises an integral transit time trigger pickup circuit and a phase difference integral pickup circuit;

[0014] The input ends of the integral transit time trigger pickup circuit and the phase difference integral pickup circuit are both connected to the output end of the digital pulse forming circuit.

[0015] Preferably, the flow rate measurement module includes a constant current charge and discharge circuit, an amplifier circuit, an A / D conversion circuit and a flow rate calculation unit;

[0016] The input end of the constant current charge and discharge circuit is respectively connected to the output end of the integral transit time trigger pickup circuit and the phase difference integral pickup circuit, and the output end is connected to the input end of the amplifier circuit;

[0017] The input end of the A / D conversion circuit is connected to the output end of the amplifier circuit, and the output end is connected to the input end of the flow rate calculation unit.

[0018] Preferably, the reference pulse generation module includes a timing control unit, a receiving reference pulse generation circuit, a transmitting reference pulse generation circuit and a trigger pulse control circuit;

[0019] The output end of the timing control unit is respectively connected to the input ends of the receiving reference pulse generating circuit, the transmitting reference pulse generating circuit, the integral transit time trigger pickup circuit and the n-time phase difference integral pickup circuit;

[0020] The output end of the transmitting reference pulse generating circuit is respectively connected to the input end of the trigger pulse control circuit and the integral transit time trigger pickup circuit;

[0021] The output end of the receiving reference pulse generating circuit is connected to the input end of the phase difference integration picking circuit.

[0022] Preferably, the whole-transit-time triggered pickup circuit comprises a first differentiator, a first gate circuit and a first trigger;

[0023] The input end of the first differentiator is connected to the output end of the digital pulse forming circuit, and the output end is connected to the input end of the first gate circuit, and the input end of the first gate circuit is also connected to the output end of the timing control unit;

[0024] The input end of the first trigger is respectively connected to the output end of the transmission reference pulse generating circuit, the timing control unit and the first gate circuit, and the output end is connected to the input end of the constant current charging and discharging circuit.

[0025] Preferably, the phase difference integral pickup circuit comprises a second differentiator, an n-order phase difference enabling window generator, a gate circuit and a second trigger;

[0026] The output end of the receiving reference pulse generating circuit is respectively connected to the input end of the second differentiator and the n-order phase difference enabling window generator, the input end of the n-order phase difference enabling window generator is also connected to the output end of the timing control unit, and the output end of the second differentiator and the output end of the n-order phase difference enabling window generator are respectively connected to the input end of the second gate circuit;

[0027] The output ends of the second gate circuit and the digital pulse forming circuit are both connected to the input end of the second trigger, and the output end of the second trigger is connected to the input end of the constant current charging and discharging circuit.

[0028] On the other hand, a control method of an ultrasonic flow measuring device is adopted, comprising the following steps:

[0029] The reference pulse generating module drives the downstream ultrasonic transducer / upstream ultrasonic transducer alternately through the signal channel switching circuit to send ultrasonic signals to the upstream ultrasonic transducer / downstream ultrasonic transducer, thereby obtaining ultrasonic signals of downstream transmission-upstream reception and upstream transmission-downstream reception;

[0030] The upstream ultrasonic transducer and the downstream ultrasonic transducer respectively send the received downstream transmission-upstream reception and upstream transmission-downstream reception ultrasonic signals to the ultrasonic signal control module;

[0031] The ultrasonic control module converts the received ultrasonic signals of downstream transmission-upstream reception and upstream transmission-downstream reception into rectangular pulse signals of downstream transmission-upstream reception and upstream transmission-downstream reception, respectively, and sends the rectangular pulse signals of downstream transmission-upstream reception and upstream transmission-downstream reception to the asynchronous integral time difference and phase difference measurement module respectively;

[0032] The asynchronous integral time difference and phase difference measurement module respectively performs integral transit time and n times of asynchronous phase difference integral measurement on the rectangular pulse signal during upstream transmission and downstream reception and the reference time scale sent by the reference pulse generation module, and obtains the integral cycle propagation time and n times of phase difference of the ultrasonic signal in the case of upstream transmission and downstream reception;

[0033] The asynchronous integral time difference and phase difference measurement module respectively performs integral transit time and n times of asynchronous phase difference integral measurement on the rectangular pulse signal during downstream transmission and upstream reception and the reference time scale sent by the reference pulse generation module, and obtains the integral cycle propagation time and n times of phase difference of the ultrasonic signal in the case of downstream transmission and upstream reception;

[0034] The flow rate measurement module calculates the flow rate and volume flow of the fluid to be measured based on the entire transit time and n-order phase difference of the ultrasonic signal in the case of upstream transmission and downstream reception, the entire transit time and n-order phase difference of the ultrasonic signal in the case of downstream transmission and upstream reception, as well as ultrasonic propagation parameters and the pipeline parameters of the fluid to be measured.

[0035] Preferably, the processing steps of the asynchronous integrated time difference and phase difference measurement module include:

[0036] Under the action of the timing control unit, the whole transit time triggers the pickup circuit to measure the whole cycle propagation time between the first ultrasonic signal sent by the downstream ultrasonic transducer / upstream ultrasonic transducer and the rising edge of the first sending reference pulse after the upstream ultrasonic transducer / downstream ultrasonic transducer receives the first ultrasonic signal;

[0037] When receiving a rectangular pulse signal with a stable amplitude, the n-time phase difference integration pickup circuit measures n phase differences between the received rectangular pulse signal with a stable amplitude and a reference pulse signal.

[0038] Preferably, the flow rate determination module processing steps include:

[0039] Generate a voltage signal proportional to the pulse width of the phase difference pulse signal according to the n phase difference pulse signals and the standard pulse signal with a pulse width of Y1;

[0040] Performing linear amplification processing on the voltage signal proportional to the pulse width, and performing analog-to-digital conversion processing after the amplification processing to obtain a binary digital signal corresponding to the voltage signal;

[0041] According to the binary digital signal and the whole cycle propagation time in the case of upstream transmission and downstream reception, the ultrasonic signal propagation time T1 in the case of upstream transmission and downstream reception is calculated;

[0042] According to the binary digital signal and the whole cycle propagation time in the case of downstream transmission and upstream reception, the ultrasonic signal propagation time T2 in the case of downstream transmission and upstream reception is calculated;

[0043] Calculate the flow rate of the fluid to be measured based on the ultrasonic signal propagation time T1, T2, the path length of the ultrasonic wave propagation in the fluid pipeline to be measured, and the angle between the ultrasonic wave propagation direction and the fluid flow direction;

[0044] The volume flow rate of the fluid to be measured is calculated according to the flow velocity of the fluid and the parameters of the fluid pipeline to be measured.

[0045] Compared with the prior art, the present invention has the following technical effects: the present invention installs a downstream ultrasonic transducer and a countercurrent ultrasonic transducer in the mounting seat of the pipe wall of the fluid pipeline to be measured, and switches the channel so that the downstream ultrasonic transducer and the countercurrent ultrasonic transducer send ultrasonic waves alternately. The ultrasonic wave sent by the downstream ultrasonic transducer propagates in the fluid pipeline for a period of time and is received by the countercurrent ultrasonic transducer, which is a downstream send-countercurrent receive ultrasonic signal. The ultrasonic wave sent by the countercurrent ultrasonic transducer propagates in the fluid pipeline for a period of time and is received by the downstream ultrasonic transducer, which is a countercurrent send-downstream receive ultrasonic signal. The downstream send-countercurrent receive ultrasonic signal and the countercurrent send-downstream receive ultrasonic signal are respectively integrated with the reference time scale in time difference and phase difference, so as to obtain the propagation time T1 of the countercurrent send-downstream receive ultrasonic signal in the fluid pipeline and the propagation time T2 of the downstream send-countercurrent receive ultrasonic signal in the fluid pipeline. According to the propagation time T1, T2, the path length of the ultrasonic wave propagation, and the angle between the ultrasonic wave propagation direction and the fluid flow direction, the flow rate of the fluid to be measured can be solved. In the solution process, only the propagation times T1 and T2 are variables, and there is no need to consider the propagation speed of ultrasound in the fluid medium. This avoids the inaccurate fluid velocity measurement caused by the influence of changes in medium temperature, pressure and impurity content on the sound speed, and improves the real-time and measurement accuracy of measuring different fluid media. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings:

[0047] Figure 1 It is a schematic diagram of an ultrasonic flow measuring device;

[0048] Figure 2 It is a schematic diagram of the structure of an ultrasonic flow measuring device;

[0049] Figure 3 It is a structural schematic diagram of a signal channel switching circuit;

[0050] Figure 4 It is a structural diagram of a bandpass frequency selective amplifier circuit;

[0051] Figure 5 It is a schematic diagram of the structure of a digital pulse forming circuit;

[0052] Figure 6 It is a specific circuit structure diagram of the entire transit time trigger pickup circuit;

[0053] Figure 7 It is a timing diagram of extracting the entire time difference of ultrasonic propagation;

[0054] Figure 8 It is a specific circuit structure diagram of a phase difference integral pickup circuit;

[0055] Fig. 9 It is a timing diagram of phase difference extraction corresponding to ultrasonic wave propagation and standard time scale pulse;

[0056] Fig.10 It is a structural diagram of a constant current charge and discharge circuit;

[0057] Fig.11 It is a schematic diagram of the structure of the amplifier circuit;

[0058] Fig.12 It is a schematic diagram of the structure of the A / D conversion circuit;

[0059] Fig.13 It is a structural schematic diagram of a flow rate calculation unit;

[0060] Fig.14 It is a schematic diagram of the structure of the timing control unit;

[0061] Fig.15 It is a structural schematic diagram of a receiving reference pulse generating circuit;

[0062] Fig.16 It is a structural schematic diagram of a transmission reference pulse generating circuit;

[0063] Fig.17 It is a schematic diagram of the use process of an ultrasonic flow measuring device;

[0064] Fig.18 The present invention is a flow chart of an ultrasonic flow measurement method. DETAILED DESCRIPTION

[0065] In order to further illustrate the features of the present invention, please refer to the following detailed description and drawings of the present invention. The drawings are for reference and illustration only and are not intended to limit the scope of protection of the present invention.

[0066] The embodiments of the present application provide a device combining asynchronous integral time difference and phase difference ultrasonic flow measurement to solve the problem that the phase difference flow measurement cannot measure the fluid medium whose upstream and downstream propagation time exceeds one cycle, and the problem that the amplitude of the first ultrasonic waveform received by the phase difference method is small and temperature compensation is required, which affects the stability and accuracy of the fluid flow rate measurement.

[0067] The technical solution in the embodiments of the present application is to solve the problems of poor stability and low accuracy in the above-mentioned fluid flow measurement using the phase difference method and the time difference method, by alternately sending a downstream ultrasonic beam and a upstream ultrasonic beam, and performing integral transit time and n asynchronous phase difference integral measurements on the received downstream ultrasonic beam and upstream ultrasonic beam, the time for the ultrasonic wave to propagate downstream in the pipeline and the time for the ultrasonic wave to propagate upstream in the pipeline are obtained, and these two propagation times are used as the only variables to calculate the flow rate of the pipeline fluid.

[0068] See also Figure 1 to Figure 2 As shown, this embodiment provides an ultrasonic flow measurement device, which includes an ultrasonic signal control module 10, an asynchronous integral time difference and phase difference measurement module 20, a flow velocity measurement module 30, a reference pulse generation module 40, and a downstream ultrasonic transducer 51 and a downstream ultrasonic transducer 52 installed in a fluid pipeline wall mounting seat; the input / output ends of the downstream ultrasonic transducer 51 and the upstream ultrasonic transducer 52 are both connected to the output / input ends of the ultrasonic signal control module 10, the output end of the ultrasonic signal control module 10 is connected to the input end of the asynchronous integral time difference and phase difference measurement module 20, and the output end of the asynchronous integral time difference and phase difference measurement module 20 is connected to the input end of the flow velocity measurement module 30; the output end of the reference pulse generation module 40 is respectively connected to the input ends of the ultrasonic signal control module 10 and the asynchronous integral time difference and phase difference measurement module 20.

[0069] Among them, the downstream ultrasonic transducer 51 and the upstream ultrasonic transducer 52 are installed in different mounting seats set on the wall of the fluid pipeline to be measured, and the reference pulse generating module alternately controls the downstream ultrasonic transducer 51 to send the downstream ultrasonic beam to the upstream ultrasonic transducer 52 and the upstream ultrasonic transducer 52 to send the upstream ultrasonic beam to the downstream ultrasonic transducer 51 through the signal channel switching circuit. The asynchronous integral time difference and phase difference measuring module 20 performs synchronous integral measurement of the entire transit time and n times phase difference of the beam received by the downstream ultrasonic transducer 51 and the standard time scale pulse, and performs synchronous integral measurement of the entire transit time and n times phase difference of the beam received by the upstream ultrasonic transducer 52 and the standard time scale pulse, respectively. The flow rate measuring module 30 processes the measurement results of the asynchronous integral time difference and phase difference measuring module 20 to obtain the propagation time of the ultrasonic wave during downstream transmission-upstream reception and the propagation time of the ultrasonic wave during upstream transmission-downstream reception, and uses these two propagation times as the only variables to calculate the flow rate of the pipeline fluid.

[0070] During the asynchronous integral time difference and phase difference measurement module 20 performing synchronous integration processing of the entire transit time and n phase differences, the received ultrasonic beam is processed under the action of the standard time scale pulse signal output by the reference pulse generation module and its timing control signal to obtain the synchronous integration results of the entire transit time and n phase differences.

[0071] See also Figure 2As shown, the ultrasonic signal control module 10 includes a signal channel switching circuit 11, a bandpass frequency selection amplifier circuit 12 and a digital pulse forming circuit 13; the input end of the signal channel switching circuit 11 is respectively connected to the output ends of the trigger pulse control circuit 44, the downstream ultrasonic transducer 51 and the upstream ultrasonic transducer 52, and the output end is respectively connected to the input ends of the bandpass frequency selection amplifier circuit 12, the downstream ultrasonic transducer 51 and the upstream ultrasonic transducer 52; the output end of the bandpass frequency selection amplifier circuit 12 is connected to the input end of the digital pulse forming circuit 13.

[0072] See also Figure 3 As shown, the connection relationship between the signal channel switching circuit 11 and the downstream ultrasonic transducer 51 and the upstream ultrasonic transducer 52 is: the downstream ultrasonic transducer 51 and the upstream ultrasonic transducer 52 are respectively connected to the two channels A and B of the bidirectional analog switch, and the ultrasonic transmitting and receiving signals are connected to the common channel of the bidirectional analog switch, wherein the bidirectional analog switch is the main component of the signal channel switching circuit 11.

[0073] The signal channel switching circuit 11 is used to switch between channel A and channel B, and to alternately send ultrasonic beams for downstream transmission and upstream reception and ultrasonic beams for upstream transmission and downstream reception to the bandpass frequency selection amplifier circuit 12 .

[0074] See also Figure 4 As shown, the bandpass frequency selection amplifier circuit 12 includes a bandpass frequency selection network and a first linear operational amplifier. The ultrasonic receiving signal output by the signal channel switching circuit 11 is connected to the input end of the bandpass frequency selection network, and the output end of the bandpass frequency selection network is connected to the input end of the first linear operational amplifier.

[0075] The bandpass frequency selection amplifier circuit 12 is used to remove the high-frequency and low-frequency components in the ultrasonic beam, and the ultrasonic receiving signal with a stable intermediate frequency band obtained after removing the high-frequency and low-frequency components is amplified by the first linear operational amplifier and then sent to the digital pulse forming circuit 13.

[0076] See also Figure 5 As shown, the digital pulse forming circuit 13 is specifically a high-speed comparator, and the output end of the frequency-selective amplifier circuit 12 is connected to the input end of the high-speed comparator. The digital pulse forming circuit 13 is used to convert the received ultrasonic waveform in the amplified intermediate frequency band into a rectangular pulse waveform that can be digitally processed, thereby converting the analog signal received by the ultrasonic wave into a pulse signal with very steep upper and lower edges, which is convenient for subsequent circuit processing.

[0077] See also Figure 2As shown, the asynchronous integral time difference and phase difference measurement module 20 includes an integral transit time trigger pickup circuit 21 and a phase difference integral pickup circuit 22; the input ends of the integral transit time trigger pickup circuit 21 and the phase difference integral pickup circuit 22 are both connected to the output end of the digital pulse forming circuit 13.

[0078] See also Figure 6 As shown, the entire transit time trigger pickup circuit 21 includes a first differentiator 211, a first gate circuit 212 and a first trigger 213; the input end of the first differentiator 211 is connected to the output end of the digital pulse forming circuit 13, and the output end is connected to the input end of the first gate circuit 212, the timing control signal output by the timing control unit 41 is respectively connected to the input ends of the first gate circuit 212 and the first trigger 213, the input end of the first trigger 213 is also connected to the sending reference pulse generating circuit 43 and the output end of the first gate circuit 212, and the output end is connected to the input end of the flow rate measurement module 30.

[0079] Among them, the timing control signal output by the timing control unit 41 is connected to the reset input terminal of the first trigger 213, the output terminal of the first gate circuit 212 is connected to the set input terminal of the first trigger 213, and the output terminal of the sending reference pulse generating circuit 43 is connected to the trigger input terminal of the first trigger 213.

[0080] See also Figure 7As shown, the whole transit time measurement principle is: under the timing logic control of the reference pulse generating module 40, when the downstream ultrasonic transducer 51 or the upstream ultrasonic transducer 52 sends the first ultrasonic signal, the timing control signal output by the timing control unit 41 is sent to the reset input terminal of the first trigger 213, the first trigger 213 is reset to output a low level, and the timer in the single-chip microcomputer starts timing synchronously; this reset control signal is valid until the ultrasonic transmission signal ends, when the first differentiator 211 receives the first digitally processable receiving pulse waveform, it outputs a high / low level very narrow differential pulse signal to the input terminal of the first gate circuit 212, and the first gate circuit 212 simultaneously outputs a high / low level very narrow differential pulse signal to the set input terminal of the first trigger 213, and the first trigger 213 outputs a high level when receiving the high / low level very narrow differential pulse, and then the first trigger 213 outputs a high level when receiving the rising edge of the sending reference pulse signal. The trigger 213 outputs a low level, and at the falling edge of the output of the first trigger 213, the timer in the microcontroller is triggered to stop timing. The timer count value is an integer multiple of the standard time-mark pulse signal period, thereby obtaining the entire cycle time of the ultrasonic signal of upstream transmission-downstream reception or the entire cycle time T3 of the ultrasonic signal of downstream transmission-upstream reception; then the Y1 pulse width is measured, and the specific measurement process is as follows: at the beginning of the measurement, the first trigger 213 outputs a low level, and the reset and set input terminals are disabled. The rising edge of the sending reference pulse signal output by the sending reference pulse generating circuit 43 triggers the first trigger 213 to output a high level, and the rising edge of the next cycle of the sending reference pulse signal triggers the first trigger 213 to output a low level, and then the timing control signal sends a reset signal to keep the output of the first trigger 213 at a low level. At this time, a standard pulse with a width of one cycle Y1 is obtained and sent to the flow rate measurement module 30 for subsequent processing.

[0081] It should be noted that the whole cycle propagation time of the ultrasonic signal measured by the whole transit time trigger pickup circuit 21 is an integer multiple of the standard time scale pulse signal period. Since the standard pulse signal has a much higher rising edge stability than the first received ultrasonic pulse signal, its measurement accuracy and stability can be guaranteed.

[0082] See also Figure 8As shown, the phase difference integral pickup circuit 22 includes a second differentiator 221, an n-order phase difference enable window generator 222, a second gate circuit 223 and a second trigger 224; the output end of the receiving reference pulse generating circuit 42 is respectively connected to the input end of the second differentiator 221 and the n-order phase difference enable window generator 222, and the output end of the second differentiator 221 and the n-order phase difference enable window generator 222 is respectively connected to the input end of the second gate circuit 223; the output end of the second gate circuit 223 and the digital pulse forming circuit 13 are both connected to the input end of the second trigger 224, and the output end of the second trigger 224 is connected to the input end of the flow rate measurement module 30.

[0083] The output end of the second gate circuit 223 is connected to the reset input end of the second flip-flop 224, and the output end of the digital pulse forming circuit 13 is connected to the trigger input end of the second flip-flop 224. Fig. 9 As shown in the figure, the phase difference measurement principle between the rectangular pulse that can be digitally processed and the standard time-scale pulse is as follows: according to the actual test results of different working conditions, the amplitude of the ultrasonic receiving signal can reach stability after at most 5 signal cycles; in practical applications, according to the spacing between the sending and receiving transducers of different calibers and the propagation speed of ultrasonic waves at different fluid temperatures, the time interval from the sending to the stabilization of the receiving signal amplitude can be calculated in advance, and by controlling the number of ultrasonic sending pulse signals, the pulse sequence of n phase difference measurements is in the stable state of the ultrasonic receiving signal amplitude under different working conditions. within a certain range; the timing control unit outputs the timing control signal according to the preset time interval and receives the standard time-mark pulse signal output by the reference pulse generating circuit 42, which are inputted into the n-time phase difference enabling window generator 222, and the n-time phase difference enabling window generator 222 is turned on. The standard time-mark pulse signal is synchronously sent to the second differentiator 221, and the second differentiator 221 outputs a differential pulse signal with a very narrow high / low level to the second gate circuit 223. The n-time phase difference enabling window generator 222 outputs the n-time standard time-mark pulse width signal to the second gate circuit 223. The gate circuit 223 outputs n high / low level very narrow pulse signals to the reset end of the second trigger 224 according to the two received signals, and controls the second trigger 224 to output a low level. The digital pulse forming circuit 13 synchronously sends the digitally processable rectangular pulse to the trigger input end of the second trigger 224, and triggers the second trigger 224 to output a high level at the rising edge of the digitally processable rectangular pulse signal. Fig. 9 As shown, n phase differences T5 between the received ultrasonic beam and the standard time-scale pulse can be obtained.

[0084] It should be noted that the n phase differences in this embodiment are generated by triggering the received pulse signal with stable amplitude and the standard time scale pulse. Therefore, the n phase difference pulse width signals need to be charged with constant current and sampled and amplified to maximize the measurement resolution.

[0085] See also Figure 2 As shown, the flow rate measurement module 30 includes a constant current charge and discharge circuit 31, an amplifier circuit 32, an A / D conversion circuit 33 and a flow rate calculation unit 34; the input end of the constant current charge and discharge circuit 31 is respectively connected to the output end of the integral transit time trigger pickup circuit 21 and the phase difference integral pickup circuit 22, and the output end is connected to the input end of the amplifier circuit 32; the input end of the A / D conversion circuit 33 is connected to the output end of the amplifier circuit 32, and the output end is connected to the input end of the flow rate calculation unit 34.

[0086] See also Fig.10 As shown, the constant current charge and discharge circuit 31 includes a constant current source and a charge and discharge network. The output ends of the entire transit time trigger pickup circuit 21 and the phase difference integral pickup circuit 22 are respectively connected to the input end of the constant current source, and the output end of the constant current source is connected to the input end of the charge and discharge network.

[0087] In practical applications, the entire transit time and the n-times integrated phase difference are measured in sequence: the entire transit time T3 is an integer multiple of Y1, the integer multiple value of Y1 is obtained by the timer of the single-chip microcomputer and the standard time scale pulse with a pulse width of Y1 is sent to the constant current charge and discharge circuit 31, where only a single Y1 is charged and discharged with a constant current, which can improve the measurement resolution and accuracy.

[0088] In the n-times integrated phase difference measurement, since the single phase difference T5 value obtained by the n-times phase difference integral pickup circuit 22 is small, the measurement stability cannot be guaranteed, so the n phase differences are sent to the constant current charge and discharge circuit 31. The above-mentioned Y1 standard pulse width for measuring the whole transit time and the n-times integrated phase difference are passed through the constant current charge and discharge circuit 31, and the voltage signals proportional to the pulse widths of Y1 and n T5 are output in sequence, and then the voltage signals are output to the amplifier circuit 32.

[0089] See also Fig.11 As shown, the amplifier circuit 32 includes a second linear operational amplifier and a voltage follower, the output end of the constant current charge and discharge circuit 31 is connected to the input end of the second linear operational amplifier, and the output end of the linear operational amplifier is connected to the input end of the voltage follower.

[0090] The function of the amplifier circuit 32 is to linearly amplify the voltage signal proportional to the pulse width signal, and output the amplified voltage signal to the A / D conversion circuit 33. In practical applications, the amplitude of the voltage signal proportional to the pulse width signal is relatively low, and by linearly amplifying the voltage signal, the accuracy of ultrasonic wave propagation time calculation is improved, thereby improving the accuracy of micro flow velocity measurement.

[0091] See also Fig.12 As shown, the A / D conversion circuit 33 is an A / D conversion chip or an A / D conversion module built into a single chip microcomputer, and the output end of the amplifier circuit 32 is connected to the input end of the A / D conversion circuit 33. The A / D conversion circuit 33 converts the amplified analog voltage signal into a corresponding binary digital signal and sends it to the flow rate calculation unit 34.

[0092] See also Fig.13 As shown, the binary digital signal output by the A / D conversion circuit 33 is input into the timer and computing components in the single-chip microcomputer for calculation, thereby calculating the ultrasonic propagation time T1 in the case of downstream transmission and upstream reception, and the ultrasonic propagation time T2 in the case of upstream transmission and downstream reception.

[0093] See also Figure 2 As shown, the reference pulse generating module 40 includes a timing control unit 41, a receiving reference pulse generating circuit 42, a sending reference pulse generating circuit 43 and a trigger pulse control circuit 44; the multi-channel output ends of the timing control unit 41 are respectively connected to the input ends of the receiving reference pulse generating circuit 42, the sending reference pulse generating circuit 43, the entire transit time trigger pickup circuit 21 and the n-time phase difference integral pickup circuit 22, and the output end of the sending reference pulse generating circuit 43 is respectively connected to the input end of the trigger pulse control circuit 44 and the entire transit time trigger pickup circuit 21; the output end of the receiving reference pulse generating circuit 42 is connected to the input end of the phase difference integral pickup circuit 22; the output end of the trigger pulse control circuit 44 is connected to the input end of the signal channel switching circuit 11, and the function of the reference pulse generating module 40 is to output the timing control signal and the standard time-scale pulse signal under the action of the timing control signal to the ultrasonic signal control module 10 and the asynchronous integral time difference and phase difference measurement module 20 to measure the flow rate.

[0094] See also Fig.14As shown, the structure of the timing control unit 41 is as follows: the single-chip program instruction controls the timing controller in the single-chip to output the sending reference pulse signal, receive the receiving reference pulse, and output multiple timing control signals. The output end of the timing control unit 41 is respectively connected to the input end of the sending reference pulse generating circuit 43, the receiving reference pulse generating circuit 42, the whole transit time trigger pickup circuit 21, and the n-time phase difference integral pickup circuit 22. The sending reference pulse generating circuit 43 generates a continuous sending pulse signal with a duty cycle of 50% under the control of the timing logic output by the timing control unit 41. This signal is input to the trigger pulse control circuit 44 to generate n sending pulse sequences with a duty cycle of 50%, which are applied to the downstream ultrasonic transducer 51 or the upstream ultrasonic transducer 52 through the signal channel switching circuit 11. At the same time, the sending reference pulse generating circuit 43 outputs a sending reference time scale pulse signal to the whole transit time trigger pickup circuit 21, which is used to measure the number of reference time scale cycles of the whole transit time. Under the timing control logic output by the timing control unit 41, the receiving reference pulse generating circuit 42 enables the output of the receiving reference timing pulse signal to the n-time phase difference integral pickup circuit 22 according to the preset time interval (the time interval from sending to receiving amplitude stabilization). Note: The sending and receiving reference pulse signals have the same period and phase, but the output signal enable opening time is different.

[0095] See also Fig.15 As shown, in the receiving reference pulse generating circuit 42, the pulse signal output by the timer in the single chip and the receiving reference pulse timing control signal output by the timing control unit 41 are input to the first logic gate circuit, and the first logic gate circuit outputs the receiving reference pulse signal.

[0096] See also Fig.16 As shown, in the sending reference pulse generating circuit 43, the pulse signal output by the timer in the single chip and the sending reference pulse timing control signal output by the timing control unit 41 are input to the second logic gate circuit together, and the second logic gate circuit outputs the sending reference pulse signal.

[0097] It should be noted that, see Fig.17 The working process of an ultrasonic flow measuring device provided in this embodiment is as follows:

[0098] (1) The reference pulse generating circuit 43 sends a pulse sequence of n pulses with a duty cycle of 50% to the channel switching circuit 11 under the intervention of the timing control unit 41. The pulse sequence is applied to the countercurrent ultrasonic transducer 52R by the trigger pulse control circuit 44. b The reference pulse generating circuit 43 sends the reference time pulse signal synchronously and starts timing. The ultrasonic signal propagates in the measuring pipeline for a period of time and reaches the downstream ultrasonic transducer 51R. a ;

[0099] (2) Downstream ultrasonic transducer 51R a The received signal is sent to the bandpass frequency selection amplifier circuit 12 through the channel switching circuit 11. After removing the high-frequency and low-frequency components generated, the ultrasonic signal in the intermediate frequency band is sent to the digital pulse forming circuit 13. The digital pulse forming circuit 13 converts the received ultrasonic waveform into a pulse signal that can be digitally processed, i.e., a rectangular pulse.

[0100] (3) The digital pulse forming circuit 13 inputs the rectangular pulse waveform into the full-transit-time trigger pickup circuit 21;

[0101] (4) The whole transit time trigger pickup circuit 21 measures the time between the first ultrasonic signal sent by the upstream ultrasonic transducer 52 and the rising edge of the first transmitted reference pulse after the first ultrasonic signal is received by the downstream ultrasonic transducer 51, which is the whole cycle propagation time of the ultrasonic signal. At the same time, a standard pulse width signal with a pulse width of Y1 is sent to the constant current charge and discharge circuit 31, and a voltage signal proportional to the pulse width signal is output;

[0102] (5) sending the rectangular pulse to the n-time phase difference integral pickup circuit 22, and the n-time phase difference integral pickup circuit 22 obtains n phase differences between the rectangular pulse and the standard time-mark pulse according to the received rectangular pulse and the standard time-mark pulse;

[0103] (6) Under the control logic of the timing control unit 41, the n-time phase difference integral pickup circuit 22 sends the pulse width signals of n T5 to the constant current charge and discharge circuit 31, and outputs a voltage signal proportional to the pulse width signal;

[0104] (7) The amplifier circuit 32 linearly amplifies the voltage signal;

[0105] (8) The amplified voltage signal is input to the A / D conversion circuit 33, and the A / D conversion circuit 33 outputs a binary digital signal corresponding to the analog voltage signal;

[0106] (9) The flow velocity calculation unit receives the above binary digital signal and can calculate the propagation time T1 = T3 - T5 of the ultrasonic signal when it is sent upstream and received downstream;

[0107] (10) Change the transmission to downstream and the reception to upstream, and repeat the above steps to obtain the ultrasonic signal downstream transmission-upstream reception propagation time T2;

[0108] (11) The flow velocity calculation unit can calculate the fluid flow velocity V and volume flow Q based on the propagation times T1 and T2, the path length L of the ultrasonic wave propagation, the angle θ between the ultrasonic wave propagation direction and the fluid flow direction, and the inner diameter D of the pipe, where:

[0109] The calculation formula of fluid flow rate V is:

[0110]

[0111] The calculation formula for the volume flow rate Q of the fluid to be measured is:

[0112]

[0113] It should be noted that this embodiment calculates the flow rate of the fluid to be measured by taking the ultrasonic wave propagation time downstream and upstream as the only variable, without considering the parameter of the ultrasonic wave propagation speed C in the fluid medium, thereby avoiding the influence of the sound speed C on the fluid velocity measurement results due to the change of the temperature, pressure and impurity content of the fluid medium, and improving the measurement applicability and measurement accuracy of the fluid medium under different working conditions. Considering that the propagation time of the ultrasonic wave in the fluid medium will be different in different measurement cycles of the fluid medium parameters, that is, T1 and T2 will change accordingly, this scheme measures T1 and T2 in each measurement cycle, thereby improving the real-time performance and measurement accuracy of measuring different fluid media.

[0114] like Fig.18 As shown, this embodiment further provides a corresponding method for idling an ultrasonic flow measuring device based on the above ultrasonic flow measuring device, and the method comprises the following steps:

[0115] S1, the reference pulse generating module 40 alternately drives the downstream ultrasonic transducer 51 / upstream ultrasonic transducer 52 to send ultrasonic signals to the upstream ultrasonic transducer 52 / downstream ultrasonic transducer 51, and obtains ultrasonic signals of downstream sending-upstream receiving and upstream sending-downstream receiving;

[0116] It should be noted that, in this embodiment, the ultrasonic wave sent by the downstream ultrasonic transducer 51 and received by the upstream ultrasonic transducer 52 is regarded as an ultrasonic signal sent downstream and received upstream, and the ultrasonic wave sent by the upstream ultrasonic transducer 52 and received by the downstream ultrasonic transducer 51 is regarded as an ultrasonic signal sent upstream and received downstream.

[0117] S2, the upstream ultrasonic transducer 52 and the downstream ultrasonic transducer 51 respectively send the received downstream transmission-upstream reception and upstream transmission-downstream reception ultrasonic signals to the ultrasonic signal control module 10;

[0118] S3, the ultrasonic control module converts the received ultrasonic signals of downstream transmission-upstream reception and upstream transmission-downstream reception into rectangular pulse signals of downstream transmission-upstream reception and upstream transmission-downstream reception, respectively, and sends the rectangular pulse signals of downstream transmission-upstream reception and upstream transmission-downstream reception to the asynchronous integral time difference and phase difference measurement module 20 respectively;

[0119] S4, the asynchronous integral time difference and phase difference measurement module 20 synchronously integrates the time difference and phase difference of the rectangular pulse signal during upstream transmission and downstream reception with the reference time scale sent by the reference pulse generation module 40, and obtains the full cycle propagation time and phase difference of the ultrasonic signal in the case of upstream transmission and downstream reception;

[0120] S5, the asynchronous integral time difference and phase difference measurement module 20 synchronously integrates the time difference and phase difference of the rectangular pulse signal during the downstream transmission and upstream reception with the reference time scale sent by the reference pulse signal generation module, and obtains the full cycle propagation time and phase difference of the ultrasonic signal in the case of downstream transmission and upstream reception;

[0121] S6. The flow rate measuring module 30 calculates the flow rate and volume flow of the fluid to be measured according to the propagation time and phase difference of the entire cycle of the ultrasonic signal in the case of upstream transmission and downstream reception, the propagation time and phase difference of the entire cycle of the ultrasonic signal in the case of downstream transmission and upstream reception, as well as the ultrasonic propagation parameters and the pipeline parameters of the fluid to be measured.

[0122] As a further preferred solution, the entire transit time trigger pickup circuit 21 processes the received digitally processable rectangular pulse under the action of the timing control signal and the reference time-mark pulse signal under the timing logic as follows:

[0123] The timing control unit 41 controls the first trigger 213 to reset when the ultrasonic control module sends the first pulse signal, so that the first trigger 213 outputs a low level and controls the timer to start timing;

[0124] The first differentiator 211 generates a high / low level differential pulse signal upon receiving the first pulse signal and outputs it to the input end of the first gate circuit 212. The first gate circuit 212 simultaneously outputs a high / low level very narrow differential pulse signal to the first trigger 213, driving the first trigger 213 to output a high level.

[0125] When the first trigger 213 receives the rising edge of the reference pulse sent by the sending reference pulse generating circuit 43, the first trigger 213 outputs a low level, and at the falling edge of the first trigger 213 output, the timer in the single-chip microcomputer is triggered to stop timing, and the timer count value is an integer multiple of the standard time-scale pulse signal period, thereby obtaining the entire cycle propagation time of the ultrasonic signal in the fluid medium; then the Y1 pulse width is measured, and the specific measurement method is as follows: at the beginning of the measurement, the first trigger 213 outputs a low level, and the reset and set input terminals are disabled. The rising edge of the sending reference pulse signal output by the sending reference pulse generating circuit 43 triggers the first trigger 213 to output a high level, and the rising edge of the next cycle of the sending reference pulse signal triggers the first trigger 213 to output a low level, and then the timing control signal sends a reset signal to keep the output of the first trigger 213 at a low level. At this time, a standard pulse with a period Y1 width is obtained and sent to the flow rate measurement module 30 for subsequent processing;

[0126] As a further preferred solution, the process of the n-time phase difference integral pickup circuit 22 processing the received digitally processable rectangular pulse under the action of the timing control signal and the standard time-scale pulse signal under the timing logic is as follows:

[0127] When the amplitude of the ultrasonic signal received by the upstream ultrasonic transducer 52 and the downstream ultrasonic transducer 51 is stable, the timing control unit 41 controls the n-order phase difference enabling window generator 222 to open;

[0128] The n-order phase difference enabling window generator 222 receives the reference pulse signal and the timing control signal sent by the receiving reference pulse generating circuit 42, obtains an enabling signal and sends it to the second gate circuit 223;

[0129] The second differentiator 221 generates a high / level differential pulse signal according to the received reference pulse signal and sends it to the second gate circuit 223;

[0130] The second gate circuit 223 generates n high / low level very narrow pulse signals according to the n-time phase difference enable signal and the high / low level differential pulse signal;

[0131] The second trigger 224 outputs a low level when receiving n high / low level very narrow pulses output by the gate circuit 223, and outputs a high level when receiving the rectangular pulse signal, so as to obtain n phase differences between the received rectangular pulse signal and the reference pulse signal.

[0132] As a further preferred solution, the flow rate measurement module 30 processing steps include:

[0133] Generate a voltage signal proportional to the pulse width of the phase difference pulse signal according to the n phase difference pulse signals and the reference pulse signal with a pulse width of Y1;

[0134] Performing linear amplification processing on the voltage signal proportional to the pulse width, and performing analog-to-digital conversion processing after the amplification processing to obtain a binary digital signal corresponding to the voltage signal;

[0135] According to the binary digital signal and the whole cycle propagation time in the case of upstream transmission and downstream reception, the ultrasonic signal propagation time T1 in the case of upstream transmission and downstream reception is calculated;

[0136] According to the binary digital signal and the whole cycle propagation time in the case of downstream transmission and upstream reception, the ultrasonic signal propagation time T2 in the case of downstream transmission and upstream reception is calculated;

[0137] According to the ultrasonic signal propagation time T1, T2, the path length L of the ultrasonic wave propagating in the measured fluid pipeline, and the angle θ between the ultrasonic wave propagation direction and the fluid flow direction, the flow velocity V of the measured fluid is calculated. The calculation formula of the fluid flow velocity V is:

[0138]

[0139] According to the flow velocity V of the fluid and the inner diameter D of the fluid pipeline to be measured, the volume flow rate of the fluid to be measured is calculated. The calculation formula of the volume flow rate Q of the fluid to be measured is:

[0140]

[0141] It should be noted that the derivation process of the calculation formula of the fluid flow rate V in this embodiment is:

[0142] Assuming that the time it takes for an ultrasonic wave to propagate in the fluid medium is T1 when the ultrasonic wave is sent from the upstream transducer to be received by the downstream transducer, we have:

[0143]

[0144] Where: C represents the propagation speed of ultrasound in the fluid medium, L represents the path of ultrasound propagation, and θ represents the angle between the ultrasound propagation direction and the fluid flow direction.

[0145] Assuming that the time for ultrasonic wave to propagate in the fluid medium is T2 when the ultrasonic wave is sent from the downstream transducer to the upstream transducer, we have:

[0146]

[0147] Since, in this embodiment, the downstream ultrasonic transducer 51 and the upstream ultrasonic transducer 52 are both fixedly mounted in the mounting seat on the wall of the fluid pipeline to be measured, in both the downstream transmission-upstream reception and the upstream transmission-downstream reception cases, the propagation path of the ultrasonic wave in the fluid medium and the angle between the ultrasonic wave propagation direction and the fluid flow direction are consistent.

[0148] Then, the time difference ΔT between the ultrasonic wave propagating downstream and upstream in the fluid medium is:

[0149]

[0150]

[0151] Since the fluid velocity V is a minimum value compared to the propagation velocity C of ultrasonic waves in the fluid medium, we have:

[0152]

[0153]

[0154] From the above formula, we can get:

[0155]

[0156]

[0157]

[0158] Compared with the existing phase difference method and time difference method, an ultrasonic velocity measurement device and a corresponding control method disclosed in this embodiment have the following advantages:

[0159] (1) Compared with the time difference method, the present device only needs to perform constant current charging and sampling amplification on the pulse width signals of n phase differences T5 and a single Y1, but does not need to perform constant current charging and discharging and sampling amplification on the entire propagation time of the ultrasonic wave in the fluid medium. Therefore, the present device can maximize the measurement resolution.

[0160] (2) Compared with the time difference method, the device triggers the output of low level when the rising edge of the standard time pulse arrives, and the single-chip microcomputer controls the timer to stop timing when the first trigger 212 outputs the falling edge. This avoids the problem of poor consistency of the rising edges of pulse signals in different measurement cycles caused by the need to convert the first tiny waveform into a digital pulse signal when using the time difference method, thereby improving the stability and measurement accuracy of flow measurement.

[0161] (3) Compared with the phase difference method, the phase difference method can only measure the fluid medium whose propagation time difference between the upstream and downstream does not exceed one pulse cycle, and it is necessary to use a table lookup method to compensate for the difference in sound velocity C at different temperatures. It is impossible to compensate for the influence of fluid medium pressure and impurity content on sound velocity C. This device does not need to consider the sound velocity C parameter during the measurement and calculation process, which improves the measurement adaptability and measurement accuracy of the fluid medium under different working conditions. Since the fluid medium parameters will be different in different measurement cycles, that is, T1+T2 will be different, it is only necessary to measure T1 and T2 in each measurement cycle, which has strong adaptability and practicality.

[0162] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An ultrasonic flow measuring device, characterized in that: It includes an ultrasonic signal control module, an asynchronous integral time difference and phase difference measurement module, a flow rate measurement module, a reference pulse generation module, and a downstream ultrasonic transducer and a reverse ultrasonic transducer installed in a fluid pipeline wall mounting seat; The input / output ends of the downstream ultrasonic transducer and the upstream ultrasonic transducer are connected to the output / input ends of the ultrasonic signal control module, the output end of the ultrasonic signal control module is also connected to the input end of the asynchronous integral time difference and phase difference measurement module, and the output end of the asynchronous integral time difference and phase difference measurement module is connected to the input end of the flow rate measurement module; The ultrasonic signal control module includes a signal channel switching circuit, a bandpass frequency selection amplifier circuit and a digital pulse forming circuit; The input end of the signal channel switching circuit is respectively connected to the trigger pulse control circuit, the output end of the downstream ultrasonic transducer and the upstream ultrasonic transducer, and the output end is respectively connected to the bandpass frequency selection amplifier circuit, the input end of the downstream ultrasonic transducer and the upstream ultrasonic transducer, the output end of the bandpass frequency selection amplifier circuit is connected to the input end of the digital pulse forming circuit, the signal channel switching circuit includes a bidirectional analog switch, and the downstream ultrasonic transducer and the upstream ultrasonic transducer are respectively connected to two channels A and B of the bidirectional analog switch; The asynchronous integral time difference and phase difference measurement module comprises an integral transit time trigger pickup circuit and a phase difference integral pickup circuit; The input ends of the integral transit time trigger pickup circuit and the phase difference integral pickup circuit are both connected to the output end of the digital pulse forming circuit, and the output end is connected to the input end of the constant current charge and discharge circuit; The flow rate measurement module includes a constant current charging and discharging circuit, an amplifying circuit, an A / D conversion circuit and a flow rate calculation unit; The input end of the constant current charge and discharge circuit is respectively connected to the output end of the integral transit time trigger pickup circuit and the phase difference integral pickup circuit, and the output end is connected to the input end of the amplifier circuit; The input end of the A / D conversion circuit is connected to the output end of the amplifier circuit, and the output end is connected to the input end of the flow rate calculation unit; The reference pulse generation module includes a timing control unit, a receiving reference pulse generation circuit, a transmitting reference pulse generation circuit and a trigger pulse control circuit; The output end of the timing control unit is respectively connected to the input ends of the receiving reference pulse generating circuit, the transmitting reference pulse generating circuit, the entire transit time trigger pickup circuit and the phase difference integral pickup circuit, and the output end of the transmitting reference pulse generating circuit is respectively connected to the input ends of the trigger pulse control circuit and the entire transit time trigger pickup circuit; The output end of the receiving reference pulse generating circuit is connected to the input end of the phase difference integral picking circuit; The whole transit time trigger pickup circuit comprises a first differentiator, a first gate circuit and a first trigger; The input end of the first differentiator is connected to the output end of the digital pulse forming circuit, and the output end is connected to the input end of the first gate circuit, and the input end of the first gate circuit is also connected to the output end of the timing control unit; The input end of the first trigger is respectively connected to the transmission reference pulse generating circuit, the timing control unit and the output end of the first gate circuit, and the output end is connected to the input end of the constant current charging and discharging circuit; The phase difference integral pickup circuit comprises a second differentiator, an n-order phase difference enabling window generator, a second gate circuit and a second trigger; The output end of the receiving reference pulse generating circuit is respectively connected to the input end of the second differentiator and the input end of the n-order phase difference enabling window generator, and the input end of the n-order phase difference enabling window generator is also connected to the output end of the timing control unit; the output ends of the second differentiator and the n-order phase difference enabling window generator are respectively connected to the input end of the second gate circuit; The output ends of the second gate circuit and the digital pulse forming circuit are both connected to the input end of the second trigger, and the output end of the second trigger is connected to the input end of the constant current charging and discharging circuit.

2. A control method for an ultrasonic flow measuring device as claimed in claim 1, characterized in that: include: The reference pulse generating module drives the downstream ultrasonic transducer / upstream ultrasonic transducer alternately to send ultrasonic signals to the upstream ultrasonic transducer / downstream ultrasonic transducer through the trigger pulse control circuit and the signal channel switching circuit, thereby obtaining ultrasonic signals of downstream transmission-upstream reception and upstream transmission-downstream reception; The upstream ultrasonic transducer and the downstream ultrasonic transducer respectively send the received downstream transmission-upstream reception and upstream transmission-downstream reception ultrasonic signals to the ultrasonic signal control module; The ultrasonic control module converts the received ultrasonic signals of downstream transmission-upstream reception and upstream transmission-downstream reception into rectangular pulse signals of downstream transmission-upstream reception and upstream transmission-downstream reception, respectively, and sends the rectangular pulse signals of downstream transmission-upstream reception and upstream transmission-downstream reception to the asynchronous integral time difference and phase difference measurement module respectively; The asynchronous integral time difference and phase difference measurement module respectively performs asynchronous integral time difference and phase difference measurement on the rectangular pulse signal during upstream transmission and downstream reception and the reference time mark sent by the reference pulse generation module to obtain the full cycle propagation time and phase difference of the ultrasonic signal under the condition of upstream transmission and downstream reception; The flow rate measurement module calculates the flow rate and volume flow of the fluid to be measured based on the full cycle propagation time and phase difference of the ultrasonic signal in the case of upstream transmission and downstream reception, the full cycle propagation time and phase difference of the ultrasonic signal in the case of downstream transmission and upstream reception, as well as the ultrasonic propagation parameters and the fluid pipeline parameters to be measured.

3. The control method according to claim 2, characterized in that: The processing steps of the asynchronous integrated time difference and phase difference measurement module include: Under the action of the timing control unit and the reference pulse signal with a pulse width of Y1, the whole transit time trigger pickup circuit measures the whole cycle propagation time between the first ultrasonic signal sent by the downstream ultrasonic transducer / upstream ultrasonic transducer and the first rising edge of the first transmitted reference pulse after the upstream ultrasonic transducer / downstream ultrasonic transducer receives the first ultrasonic signal; under the action of the timing control unit, a standard pulse signal with a cycle width of Y1 is generated. When receiving a rectangular pulse signal with a stable amplitude, the phase difference integration pickup circuit measures n phase differences between the received rectangular pulse signal with a stable amplitude and a reference pulse signal.

4. The control method according to claim 3, characterized in that: The flow rate determination module processing steps include: Generate a voltage signal proportional to the pulse width of the phase difference pulse signal according to the n phase difference pulse signals and the standard pulse signal with a pulse width of Y1; A voltage signal proportional to the pulse width is linearly amplified, and an analog-to-digital conversion is performed after the amplification process to obtain a binary digital signal corresponding to the voltage signal; According to the binary digital signal and the whole cycle propagation time in the case of upstream transmission and downstream reception, the ultrasonic signal propagation time T1 in the case of upstream transmission and downstream reception is calculated; According to the binary digital signal and the whole cycle propagation time in the case of downstream transmission and upstream reception, the ultrasonic signal propagation time T2 in the case of downstream transmission and upstream reception is calculated; Calculate the flow rate of the fluid to be measured based on the ultrasonic signal propagation time T1, T2, the path length of the ultrasonic wave propagation in the fluid pipeline to be measured, and the angle between the ultrasonic wave propagation direction and the fluid flow direction; The volume flow rate of the fluid to be measured is calculated according to the flow velocity of the fluid and the parameters of the fluid pipeline to be measured.

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