Ultrasonic flow metering device and method

Abstract

The invention relates to an ultrasonic flow metering device and a metering method thereof, and relates to the field of ultrasonic measuring devices. According to the metering device, through a cross-correlation operation circuit, a microcontroller, a double-threshold comparator, a peak detector, a gain adjustment circuit and a head wave threshold adjustment circuit, self-adaptive processing and adjustment of echo signals and head wave thresholds are achieved, and the accuracy and reliability of flow metering are improved. The metering method adopts an adaptive adjustment strategy of echo signal amplifier gain based on an output signal of an echo signal peak detection circuit, and a head wave threshold adaptive adjustment strategy based on a correlation operation value of echo signal sampling data and pre-stored reference wave data. According to the scheme, the stability of the echo signal and the rationality of the head wave threshold value are guaranteed, the method has adaptability to echo contour feature changes caused by transducer aging or contamination, and then the reliability of the flow metering process is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic measuring devices, and in particular to an ultrasonic flow metering device and method. Background Art

[0002] As a non-contact, highly repeatable flow measurement device, ultrasonic flowmeter is widely used in the industrial and scientific fields because it can adapt to various measured fluids. Traditional ultrasonic flowmeters are mainly based on the time difference method, which measures the difference in the propagation speed of ultrasonic waves in the fluid when they are downstream and upstream to solve the flow rate or flow. However, the existing technology has some limitations, such as complex flow field environment, limited sensor performance, unstable propagation signal, and severe acoustic interference, which seriously affect the measurement accuracy.

[0003] Although ultrasonic flowmeters provide an effective means of flow measurement, the existing technology faces several technical problems in practical applications. First, due to factors such as ambient temperature changes and transducer aging or contamination, the basic characteristics of the ultrasonic echo signal (such as amplitude and envelope) will change slightly, affecting the timing accuracy of the downstream flight time and upstream flight time, thereby reducing the measurement accuracy of the time difference ultrasonic flowmeter. Secondly, the ultrasonic flowmeter in the existing technology lacks sufficient flexibility and adaptability in signal processing, and it is difficult to cope with changing industrial environments and complex flow field conditions. In addition, the amplitude stability of the signal and the reasonable setting of the first wave threshold are also challenges in the existing technology. These problems limit the application of flowmeters in high-precision measurements. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an ultrasonic flow metering device and method to solve one or more problems in the prior art.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] An ultrasonic flow metering device, comprising

[0007] A cross-correlation operation circuit is used to perform a cross-correlation operation on the sampling data of a primary ultrasonic echo and the pre-stored reference wave data, and output a correlation value Rxy between the two;

[0008] A microcontroller, used for automatically adjusting the first wave threshold or updating the reference wave data according to the comparison result between the correlation value Rxy and the preset threshold;

[0009] A dual-threshold comparator is used to select the first wave threshold Vfirst as a comparison benchmark before the ultrasonic echo arrives, and select the zero-crossing threshold Vzero as a comparison benchmark after the ultrasonic echo arrives, and can detect both the positive zero-crossing point and the negative zero-crossing point at the same time;

[0010] A peak detector is used to detect the amplitude of the ultrasonic echo signal and determine whether it is stable near the set target;

[0011] The gain adjustment circuit and the first wave threshold adjustment circuit are both controlled by the microcontroller to adapt to the change of the amplitude of the ultrasonic echo signal.

[0012] In the above technical solution, the intelligentization and automation of the ultrasonic flow metering device are realized by integrating the cross-correlation operation circuit, microcontroller, dual-threshold comparator, peak detector, gain adjustment circuit and first-wave threshold adjustment circuit. The cross-correlation operation circuit can accurately calculate the correlation value between the echo signal and the reference wave, and the microcontroller automatically adjusts the first-wave threshold or updates the reference wave data according to the correlation value, thereby improving the accuracy and adaptability of flow metering. The dual-threshold comparator can detect positive and negative zero-crossing points at the same time, enhancing the flexibility and accuracy of signal processing. The coordinated use of the peak detector and the gain adjustment circuit ensures the stability of the amplitude of the echo signal, improves the signal-to-noise ratio of the signal, and thus improves the reliability of flow metering.

[0013] Further, the first transducer and the second transducer are respectively installed upstream and downstream of the flow channel for transmitting and receiving ultrasonic signals, wherein the straight-line distance L between the first transducer and the second transducer is used to calculate the propagation time of the ultrasonic signal;

[0014] The flow channel has a cross-sectional area S, which is used to calculate the fluid flow rate in combination with the fluid flow velocity v;

[0015] The angle θ between the first transducer and the second transducer and the flow channel affects the propagation path of the ultrasonic signal and is used to optimize the signal receiving efficiency;

[0016] The transceiver switching circuit is used to control the transmission and reception switching between the first transducer and the second transducer to measure the time t12 required for the ultrasonic wave to propagate from the first transducer to the second transducer, and the time t21 required for the ultrasonic wave to propagate from the second transducer to the first transducer. These times are combined with the flow velocity v and the cross-sectional area S to calculate the fluid flow rate.

[0017] In the above technical solution, by installing the first transducer and the second transducer respectively upstream and downstream of the flow channel, and combining the cross-sectional area S of the flow channel and the fluid flow velocity v, the fluid flow rate can be calculated more accurately. The setting of the straight-line distance L and the angle θ optimizes the propagation and reception of the signal and improves the measurement accuracy. The addition of the transceiver switching circuit enables the device to measure the time for the ultrasonic wave to propagate between the two transducers, providing a time parameter for flow calculation.

[0018] Furthermore, the low noise amplifier performs primary amplification on the received ultrasonic echo signal to improve the signal-to-noise ratio of the echo signal;

[0019] The variable gain amplifier further amplifies the ultrasonic echo signal to stabilize its amplitude near the set target.

[0020] In the above technical solution, the signal-to-noise ratio of the received ultrasonic echo signal is improved by using a low-noise amplifier and a variable gain amplifier, and the signal amplitude is stabilized near the set target. This signal preprocessing technology enhances the accuracy of subsequent signal processing, thereby improving the overall accuracy of flow measurement.

[0021] Further, the positive / negative zero-crossing timing circuit measures the flight time of the ultrasonic wave from emission to a series of positive / negative zero-crossing points according to the zero-crossing mark of the dual-threshold comparator;

[0022] The analog-to-digital converter starts to work from the moment when the dual-threshold comparator detects the first wave until the dual-threshold comparator outputs the last zero-crossing mark, converting the ultrasonic echo signal with stable amplitude into a digital signal.

[0023] In the above technical solution, the flight time of the ultrasonic signal can be accurately measured by the combination of the positive / negative zero-crossing timing circuit and the analog-to-digital converter, and the stable amplitude signal can be converted into a digital signal. This high-precision time measurement and signal digitization is the premise of flow measurement accuracy and provides accurate basic data for subsequent data processing and flow calculation.

[0024] Further, the received wave sampling data module serves as a storage space for the output data of the analog-to-digital converter, storing the sampled data of the received wave;

[0025] The reference wave storage data module pre-sets the reference wave storage data, or updates it in real time according to the working status of the ultrasonic flow meter.

[0026] In the above technical solution, by setting the receiving wave sampling data module and the reference wave storage data module, the necessary data storage function is provided for the flow metering device. This data storage mechanism can not only save the real-time sampling data, but also update the reference wave data in real time according to the working status, thereby enhancing the adaptability and accuracy of the device.

[0027] Furthermore, the transmitting module starts the action of transmitting ultrasonic waves by a microcontroller; the components in the ultrasonic flow metering device are implemented by a dedicated ultrasonic ASIC chip to reduce hardware costs and improve noise resistance.

[0028] In the above technical solution, the microcontroller starts the transmitting module to transmit ultrasonic waves, and a dedicated ultrasonic ASIC chip is used to implement the components in the device, thereby reducing the hardware cost and improving the anti-noise ability. The use of the ASIC chip improves the overall performance and reliability of the device, enabling it to work stably in various environments.

[0029] Furthermore, the peak detector includes a resistor string and a comparator array.

[0030] In the above technical solution, the accuracy of ultrasonic echo signal amplitude detection is improved through the design of the resistor string and comparator array in the peak detector. This accurate amplitude detection is crucial for subsequent signal processing and flow calculation, and helps to improve the accuracy and reliability of the entire flow metering device.

[0031] In order to make the technical effect complete, the second technical solution of the present invention is an ultrasonic flow measurement method, comprising the following steps:

[0032] Step 1: Use a first transducer and a second transducer to transmit and receive ultrasonic signals in the flow channel, wherein the first transducer is located upstream of the flow channel, the second transducer is located downstream of the flow channel, and the straight-line distance L and the angle θ are used to optimize signal propagation and reception;

[0033] Step 2: Based on the output signal of the echo signal peak detection circuit, realize adaptive adjustment of the echo signal amplifier gain;

[0034] Step 3: Collect the echo signal and convert it into sampling data;

[0035] Step 4: Based on the correlation calculation value between the echo signal sampling data and the pre-stored reference wave data, realize the adaptive adjustment of the first wave threshold;

[0036] Step 5: Detect the positive and negative zero-crossing points of the first wave and zero-crossing wave of an echo through a dual-threshold comparator;

[0037] Step 6: Measure the flight time of the ultrasonic signal from emission to a series of positive / negative zero crossings. These times are combined with the flow velocity v and the cross-sectional area S to calculate the fluid flow rate.

[0038] In the above technical solution, the ultrasonic flow measurement method described achieves accurate flow measurement through a series of steps. These steps include using a transducer to transmit and receive signals, adaptively adjusting the gain of an echo signal amplifier, collecting and converting echo signals, adaptively adjusting the first wave threshold, and measuring flight time. The comprehensive application of these steps improves the automation level and measurement accuracy of flow measurement.

[0039] Furthermore, in step 2, the adaptive adjustment also includes the microcontroller controlling the gain adjustment circuit to adjust the gain of the variable gain amplifier when the amplitude of the echo signal deviates from an expected range.

[0040] In the above technical solution, adaptive adjustment is added in step 2, that is, when the amplitude of the echo signal deviates from the expected range, the microcontroller controls the gain adjustment circuit to adjust the gain of the variable gain amplifier. This adjustment mechanism improves the flexibility and accuracy of signal processing, ensures that a stable signal amplitude can be obtained under different conditions, and thus improves the reliability of flow measurement.

[0041] Further, in step 4, the adaptive adjustment further includes when the correlation value Rxy is lower than a preset threshold, the microcontroller controls the first wave threshold adjustment circuit to update the first wave threshold Vfirst;

[0042] Further included in step 4, when Rxy is still lower than the preset threshold after the first wave threshold Vfirst is updated multiple times, the microcontroller controls the reference wave storage data module to update the reference wave data.

[0043] In the above technical solution, adaptive adjustment is added in step 4, including updating the first wave threshold Vfirst when the correlation value Rxy is lower than the preset threshold, and updating the reference wave data when Rxy is still lower than the preset threshold after updating the first wave threshold Vfirst multiple times. This adjustment mechanism enhances the adaptability of the device to signal changes, improves the accuracy and reliability of flow measurement, and ensures that accurate flow data can be obtained under different conditions.

[0044] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0045] (I) Through the integrated application of cross-correlation operation circuit, microcontroller, dual threshold comparator, peak detector, gain adjustment circuit and first wave threshold adjustment circuit, this integrated solution can accurately calculate the correlation value between the echo signal and the reference wave, and automatically adjust the first wave threshold or update the reference wave data based on this, thereby improving the accuracy and adaptability of flow measurement, while ensuring the flexibility and accuracy of signal processing.

[0046] (ii) Adaptive adjustment of the gain of the echo signal amplifier is achieved based on the output signal of the echo signal peak detection circuit, and adaptive adjustment of the first wave threshold is achieved based on the correlation calculation value between the echo signal sampling data and the pre-stored reference wave data. The present invention can dynamically optimize the signal processing parameters to adapt to different measurement conditions and environmental changes, thereby ensuring that reliable flow measurement results can be obtained even in a changing industrial environment.

[0047] (iii) By using a low-noise amplifier and a variable gain amplifier in cascade, the present invention improves the signal-to-noise ratio of the received ultrasonic echo signal and stabilizes the signal amplitude near the set target, providing high-quality signal input for flow measurement and improving the overall accuracy of flow measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a functional block diagram of a fluid metering device in an exemplary embodiment of the present invention.

[0049] Figure 2 It is the principle diagram of the dual threshold comparator in the present invention.

[0050] Figure 3 It is a waveform diagram of input and output signals of the dual threshold comparator in the present invention.

[0051] Figure 4 It is a schematic diagram of the peak detector in the present invention.

[0052] Figure 5 It is a schematic diagram of the correlation value calculation between the received wave and the echo in the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and exemplary descriptions. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention.

[0054] Application Overview

[0055] In the field of flow measurement, ultrasonic flowmeters are commonly used in the industry to solve the problem of measuring fluid flow rate and flow rate. Ultrasonic flowmeters calculate flow by measuring the difference in propagation time of ultrasonic waves in the downstream and upstream of the fluid. They have the advantages of being non-invasive and applicable to a variety of media. However, conventional ultrasonic flowmeters have some shortcomings, such as being sensitive to ambient temperature and transducer status, being easily affected by medium changes, and lacking sufficient flexibility and adaptability in signal processing. These problems limit the measurement accuracy and stability of the equipment in complex industrial environments. Therefore, the industry is in urgent need of an ultrasonic flow metering solution that can improve measurement accuracy, adaptability, and reliability.

[0056] Example

[0057] Please refer to Figure 1The ultrasonic flow metering device of the present invention realizes high-precision measurement of fluid flow through intelligent signal processing and adaptive adjustment. The device includes a first transducer and a second transducer, which are respectively installed upstream and downstream of the flow channel, and their straight-line distance is L, and the angle between them and the flow channel is θ. The flow channel has a cross-sectional area S, and it is assumed that the flow velocity of the fluid is v. The first transducer and the second transducer can also be installed on the same side of the flow channel to form a V-shaped ultrasonic flight path.

[0058] The transceiver switching circuit controls the transmission and reception status between the first transducer and the second transducer. When the first transducer transmits ultrasonic waves, the second transducer receives them and records the time required for the ultrasonic waves to propagate from the first transducer to the second transducer; conversely, when the second transducer transmits ultrasonic waves, the first transducer receives them and records the time required. These two time differences are key parameters for calculating the fluid flow rate.

[0059] The received ultrasonic echo signal is first amplified by a low noise amplifier to improve the signal-to-noise ratio. Then, a variable gain amplifier further amplifies the signal to stabilize its amplitude near the set target.

[0060] Before receiving the ultrasonic echo, the dual threshold comparator selects the first wave threshold as the comparison benchmark; when the comparator flips to a high level for the first time, the zero crossing threshold is immediately selected as the comparison benchmark, and then the flipping moment of the comparator is used as the zero crossing mark. The positive / negative zero crossing timing circuit measures the flight time of the ultrasonic wave from emission to a series of positive / negative zero crossings according to the above zero crossing marks, where the positive zero crossing corresponds to the rising edge moment of the dual threshold comparator, and the negative zero crossing corresponds to the falling edge moment.

[0061] The analog-to-digital converter starts working from the moment the dual-threshold comparator detects the first wave until the dual-threshold comparator outputs the last zero-crossing mark, converting the ultrasonic echo signal with a stable amplitude into a digital signal. The received wave sampling data serves as the storage space for the analog-to-digital converter output data, while the reference wave storage data is pre-set or updated in real time according to the working status of the ultrasonic flowmeter.

[0062] The cross-correlation operation circuit performs cross-correlation operation on the sampled data of an ultrasonic echo and the stored data of the reference wave, and outputs the correlation value of the two. The peak detector is used to detect the amplitude of the ultrasonic echo signal to determine whether it is stable near the set target. The microcontroller summarizes the characteristic information of the ultrasonic echo signal and performs information judgment and processing, including the flight time, correlation value and the output result of the peak detector, to calculate the downstream flight time and upstream flight time of the ultrasonic wave and the time difference between the two.

[0063] When the gain adjustment circuit is initialized at power-on, or when the amplitude of the ultrasonic echo deviates from the expected value, the microcontroller determines whether to reset the gain of the variable gain amplifier. When the first wave threshold adjustment circuit is initialized at power-on, or when the correlation value between the ultrasonic echo and the reference wave is lower than the set level, the microcontroller determines whether to reset the first wave threshold. The transmitting module starts the action of transmitting ultrasonic waves by the microcontroller.

[0064] The microcontroller calculates the flow rate of the fluid through a formula, where K is the calibration coefficient of the flow rate.

[0065]

[0066] The components in the entire device can be implemented by discrete devices or dedicated ultrasonic ASIC chips to reduce hardware costs and improve noise resistance and enhance overall performance.

[0067] Please refer to Figure 2 , Figure 3 In the specific implementation, the working process of the dual threshold comparator is as follows: Vecho is an ultrasonic echo signal, whose amplitude has stabilized near the set target, Vfirst is the first wave threshold, Vzero is the zero-crossing threshold, and Vzout is the output signal of the dual threshold comparator. When switch S1 is closed and switch S2 is open, the dual threshold comparator compares the ultrasonic echo signal Vecho with the first wave threshold Vfirst; when switch S2 is closed and switch S1 is open, the dual threshold comparator compares the ultrasonic echo signal Vecho with the zero-crossing threshold Vzero. When the dual threshold comparator starts working, the threshold is set to the first wave threshold Vfirst. The ultrasonic echo signal is a series of sine waves, and its amplitude gradually increases until it is near the stable amplitude, and then it will do attenuation oscillation. When the ultrasonic echo is greater than the first wave threshold Vfirst, the comparator outputs the first positive pulse, which means that the ultrasonic echo has reached the receiving end, and the dual threshold comparator switches to the zero-crossing threshold Vzero. After that, whenever the ultrasonic echo is greater than the threshold Vzero, the comparator outputs a positive pulse.

[0068] Please refer to Figure 4, the core circuit of the peak detector includes two parts: the resistor string on the left and the comparator array on the right. The resistor string is connected end to end and finally connected between the power supply voltage VDD and the ground. The voltage of node 0 is equal to 0.5×VDD, the voltage of node 1 is equal to vpth1, the voltage of node 2 is equal to vpth2, and so on. The voltage of node 8 is equal to vpth8. The in-phase input of all comparators is connected to the ultrasonic echo signal Vecho, the inverting input of peak comparator 1 is connected to node 1, the inverting input of peak comparator 2 is connected to node 2, and so on. The inverting input of peak comparator 8 is connected to node 8. The output signal of peak comparator 1 is recorded as Vpout1, the output signal of peak comparator 2 is recorded as Vpout2, and so on. The output signal of peak comparator 8 is recorded as Vpout8, and Vpout1~Vpout8 are transmitted to the microcontroller. The microcontroller can easily determine the amplitude of the current ultrasonic echo according to the output value of the peak detector.

[0069] Please refer to Figure 5 , in the figure, x(t) is the ultrasonic echo signal and y(t) is the ultrasonic reference signal.

[0070] The operation of the cross-correlation operation circuit is as follows: When the dual threshold comparator outputs the first wave pulse, it indicates that the ultrasonic echo has reached the receiving end. At this moment, the analog-to-digital converter starts sampling the receiving wave signal and saves the sampling data to the corresponding memory. The sampling action ends when the last zero crossing point is set. The sampling data of the reference wave can be pre-stored in the corresponding memory during the manufacturing stage of the flow metering device, or the receiving wave at zero flow can be sampled as the corresponding reference wave in a special test mode. After that, the cross-correlation operation circuit performs cross-correlation operation on the above ultrasonic echo and the reference wave to obtain the correlation value. If the correlation value is 0.8-0.95, it means that the ultrasonic echo and the reference wave are highly similar, and the first wave threshold selected by the flow metering device is reasonable; on the contrary, if the correlation value is less than 0.8, it means that there is a certain degree of deviation between the ultrasonic echo and the reference wave, which may be due to the unreasonable setting of the first wave threshold, and the system needs to reset the first wave threshold, or it may be due to the change of transducer characteristics caused by aging or contamination of the transducer. When the correlation value is less than 0.8, it is necessary to reset the first wave threshold and recalculate the correlation value of the ultrasonic echo and the reference wave. If the correlation value is greater than 0.8, the adjustment is completed. If the correlation value is less than 0.8, it is judged that the cause is aging or contamination of the transducer. At this time, it is necessary to update the reference wave stored in the system to adapt to the change in transducer characteristics.

[0071] Specific working process

[0072] The first transducer and the second transducer are installed at the upstream and downstream of the flow channel respectively, and their straight-line distance L and the angle θ between them and the flow channel are used to calculate the flow velocity and flow rate of the fluid.

[0073] When the first transducer transmits ultrasonic waves, the second transducer receives them and records the time required for the ultrasonic waves to propagate from the first transducer to the second transducer; conversely, when the second transducer transmits ultrasonic waves, the first transducer receives them and records the time required. The received ultrasonic echo signal is firstly amplified by a low-noise amplifier to improve the signal-to-noise ratio, and then the variable gain amplifier further amplifies the signal to stabilize its amplitude near the set target.

[0074] The dual threshold comparator selects the first wave threshold as the comparison benchmark before receiving the ultrasonic echo. When the comparator flips to a high level for the first time, the zero-crossing threshold is immediately selected as the comparison benchmark, and then the flipping moment of the comparator is used as the mark of the zero-crossing point.

[0075] The positive / negative zero-crossing timing circuit measures the flight time of the ultrasonic wave from emission to a series of positive / negative zero-crossing points according to the above zero-crossing point identification.

[0076] The analog-to-digital converter starts to work from the moment when the dual-threshold comparator detects the first wave until the dual-threshold comparator outputs the last zero-crossing mark, converting the ultrasonic echo signal with stable amplitude into a digital signal.

[0077] The cross-correlation operation circuit performs cross-correlation operation on the sampled data of the primary ultrasonic echo and the stored data of the reference wave, and outputs the correlation value between the two.

[0078] The microcontroller summarizes the characteristic information of the ultrasonic echo signal and performs information judgment and processing, including the flight time, correlation value and the output result of the peak detector to calculate the downstream flight time and upstream flight time of the ultrasonic wave and the time difference between the two.

[0079] When the gain adjustment circuit is initialized at power-on or the amplitude of the ultrasonic echo deviates from the expected value, the microcontroller determines whether to reset the gain of the variable gain amplifier.

[0080] When the first wave threshold adjustment circuit is initialized at power-on, or when the correlation value between the ultrasonic echo and the reference wave is lower than the set level, the microcontroller determines whether to reset the first wave threshold.

[0081] The transmitting module starts the action of transmitting ultrasonic waves by the microcontroller. The microcontroller calculates the flow rate of the fluid through a formula. K is the calibration coefficient of the flow rate. The components in the entire device can be implemented by discrete devices or dedicated ultrasonic ASIC chips to reduce hardware costs and improve noise resistance and overall performance.

[0082] The various technical features described in the above exemplary embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the various technical features in the above exemplary embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. An ultrasonic flow metering device, characterized in that: include A cross-correlation operation circuit is used to perform a cross-correlation operation on the sampling data of a primary ultrasonic echo and the pre-stored reference wave data, and output a correlation value Rxy between the two; A microcontroller, used for automatically adjusting the first wave threshold or updating the reference wave data according to the comparison result between the correlation value Rxy and the preset threshold; A dual-threshold comparator is used to select the first wave threshold Vfirst as a comparison benchmark before the ultrasonic echo arrives, and select the zero-crossing threshold Vzero as a comparison benchmark after the ultrasonic echo arrives, and can detect both the positive zero-crossing point and the negative zero-crossing point at the same time; A peak detector is used to detect the amplitude of the ultrasonic echo signal and determine whether it is stable near the set target; The gain adjustment circuit and the first wave threshold adjustment circuit are both controlled by the microcontroller to adapt to the change of the amplitude of the ultrasonic echo signal.

2. An ultrasonic flow metering device as claimed in claim 1, characterized in that: A first transducer and a second transducer are installed at the upstream and downstream of the flow channel, respectively, for transmitting and receiving ultrasonic signals, wherein a straight-line distance L between the first transducer and the second transducer is used to calculate the propagation time of the ultrasonic signal; The flow channel has a cross-sectional area S, which is used to calculate the fluid flow rate in combination with the fluid flow velocity v; The angle θ between the first transducer and the second transducer and the flow channel affects the propagation path of the ultrasonic signal and is used to optimize the signal receiving efficiency; The transceiver switching circuit is used to control the transmission and reception switching between the first transducer and the second transducer to measure the time t12 required for the ultrasonic wave to propagate from the first transducer to the second transducer, and the time t21 required for the ultrasonic wave to propagate from the second transducer to the first transducer. These times are combined with the flow velocity v and the cross-sectional area S to calculate the fluid flow rate.

3. An ultrasonic flow metering device as claimed in claim 1, characterized in that: The low noise amplifier performs primary amplification on the received ultrasonic echo signal to improve the signal-to-noise ratio of the echo signal; The variable gain amplifier further amplifies the ultrasonic echo signal to stabilize its amplitude near the set target.

4. An ultrasonic flow metering device as claimed in claim 1, characterized in that: The positive / negative zero-crossing timing circuit measures the flight time of the ultrasonic wave from emission to a series of positive / negative zero-crossing points according to the zero-crossing mark of the dual-threshold comparator; The analog-to-digital converter starts to work from the moment when the dual-threshold comparator detects the first wave until the dual-threshold comparator outputs the last zero-crossing mark, converting the ultrasonic echo signal with stable amplitude into a digital signal.

5. An ultrasonic flow metering device as claimed in claim 1, characterized in that: The receiving wave sampling data module serves as a storage space for the output data of the analog-to-digital converter and stores the sampling data of the receiving wave; The reference wave storage data module pre-sets the reference wave storage data, or updates it in real time according to the working status of the ultrasonic flow meter.

6. An ultrasonic flow metering device as claimed in claim 1, characterized in that: The transmitting module starts the action of transmitting ultrasonic waves by a microcontroller; the components in the ultrasonic flow metering device are implemented by a dedicated ultrasonic ASIC chip to reduce hardware costs and improve noise resistance.

7. An ultrasonic flow metering device as claimed in claim 1, characterized in that: The peak detector includes a resistor string and a comparator array.

8. An ultrasonic flow measurement method, based on an ultrasonic flow measurement device according to any one of claims 1 to 7, characterized in that The following steps are involved: Step 1: Use a first transducer and a second transducer to transmit and receive ultrasonic signals in the flow channel, wherein the first transducer is located upstream of the flow channel, the second transducer is located downstream of the flow channel, and the straight-line distance L and the angle θ are used to optimize signal propagation and reception; Step 2: Based on the output signal of the echo signal peak detection circuit, realize adaptive adjustment of the echo signal amplifier gain; Step 3: Collect the echo signal and convert it into sampling data; Step 4: Based on the correlation calculation value between the echo signal sampling data and the pre-stored reference wave data, realize the adaptive adjustment of the first wave threshold; Step 5: Detect the positive and negative zero-crossing points of the first wave and zero-crossing wave of an echo through a dual-threshold comparator; Step 6: Measure the flight time of the ultrasonic signal from emission to a series of positive / negative zero crossings. These times are combined with the flow velocity v and the cross-sectional area S to calculate the fluid flow rate.

9. An ultrasonic flow measurement method as claimed in claim 8, characterized in that: In step 2, the adaptive adjustment further includes the microcontroller controlling the gain adjustment circuit to adjust the gain of the variable gain amplifier when the amplitude of the echo signal deviates from the expected range.

10. An ultrasonic flow measurement method as claimed in claim 8, characterized in that: In step 4, the adaptive adjustment further includes when the correlation value Rxy is lower than the preset threshold, the microcontroller controls the first wave threshold adjustment circuit to update the first wave threshold Vfirst; Further included in step 4, when Rxy is still lower than the preset threshold after the first wave threshold Vfirst is updated multiple times, the microcontroller controls the reference wave storage data module to update the reference wave data.

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