Ultrasonic flow metering device and method

Abstract

The present invention relates to an ultrasonic flow metering device and a metering method thereof, and relates to the field of ultrasonic measuring devices. The metering device realizes adaptive processing and adjustment of the echo signal and the first wave threshold through a cross-correlation operation circuit, a microcontroller, a dual-threshold comparator, a peak detector, a gain adjustment circuit, and a first-wave threshold adjustment circuit, thereby improving the accuracy and reliability of flow measurement. The metering method adopts an adaptive adjustment strategy for the echo signal amplifier gain based on the output signal of the echo signal peak detection circuit, and an adaptive adjustment strategy for the first wave threshold based on the correlation operation value of the echo signal sampling data and the pre-stored reference wave data. This solution not only ensures the stability of the echo signal and the rationality of the first wave threshold, but also has adaptability to changes in the echo profile characteristics caused by aging or contamination of the transducer, thereby ensuring the reliability of the flow metering process.

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] Ultrasonic flowmeters, as non-contact, highly repeatable flow measurement devices, are widely used in industry and science due to their adaptability to a wide range of measured fluids. Traditional ultrasonic flowmeters primarily rely on transit-time-of-flight technology, determining flow velocity or flow rate by measuring the difference in ultrasonic wave propagation speeds in the fluid, both upstream and downstream. However, existing technologies have limitations, such as complex flow environments, limited sensor performance, unstable propagation signals, and severe acoustic interference, which significantly impact 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 changes in ambient temperature and aging or contamination of the transducer, 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 the upstream flight time, thereby reducing the measurement accuracy of the time-difference ultrasonic flowmeter. Secondly, the ultrasonic flowmeters in the existing technology lack sufficient flexibility and adaptability in signal processing, and are 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] The cross-correlation operation circuit is used to perform cross-correlation operation on the sampling data of the ultrasonic echo and the pre-stored reference wave data, and output the correlation value Rxy between the two;

[0008] A microcontroller, configured to automatically adjust a first wave threshold or update reference wave data according to a comparison result between the correlation value Rxy and a 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 simultaneously detect positive and negative zero-crossing points;

[0010] Peak detector, 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 ultrasonic echo signal amplitude.

[0012] In the above technical solution, the intelligent and automated ultrasonic flow metering device is achieved by integrating a cross-correlation operation circuit, a microcontroller, a dual-threshold comparator, a peak detector, a gain adjustment circuit, and a first-wave threshold adjustment circuit. The cross-correlation operation circuit accurately calculates the correlation between the echo signal and the reference wave. The microcontroller automatically adjusts the first-wave threshold or updates the reference wave data based on the correlation value, improving the accuracy and adaptability of flow measurement. The dual-threshold comparator can simultaneously detect positive and negative zero crossings, enhancing the flexibility and accuracy of signal processing. The combined use of the peak detector and gain adjustment circuit ensures the stability of the echo signal amplitude, improves the signal-to-noise ratio, and thus enhances the reliability of flow measurement.

[0013] Furthermore, a first transducer and a second transducer are installed 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;

[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 and second transducers and the flow channel affects the propagation path of the ultrasonic signal and is used to optimize the signal reception 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 this technical solution, by installing the first and second transducers upstream and downstream of the flow channel, respectively, and combining the channel's cross-sectional area S and the fluid velocity v, the fluid flow rate can be more accurately calculated. The linear distance L and angle θ optimize signal propagation and reception, improving measurement accuracy. The addition of a transceiver switching circuit enables the device to measure the propagation time of ultrasonic waves 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 this technical solution, the use of a low-noise amplifier and a variable-gain amplifier improves the signal-to-noise ratio of the received ultrasonic echo signal and stabilizes the signal amplitude near a set target. This signal preprocessing technology enhances the accuracy of subsequent signal processing, thereby improving the overall accuracy of flow measurement.

[0021] Furthermore, 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 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 stable amplitude into a digital signal.

[0023] In this technical solution, the positive / negative zero-crossing timing circuit and analog-to-digital converter are used together to accurately measure the ultrasonic signal's flight time and convert the stable amplitude signal into a digital signal. This high-precision time measurement and signal digitization are the prerequisites for accurate flow measurement and provide accurate basic data for subsequent data processing and flow calculation.

[0024] Furthermore, 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 stores the preset reference wave data, or updates it in real time according to the working status of the ultrasonic flowmeter.

[0026] In this technical solution, the provision of a received wave sampling data module and a reference wave storage data module provides the necessary data storage capabilities for the flow meter. This data storage mechanism not only preserves real-time sampling data but also updates the reference wave data in real time based on the operating status, enhancing the device's adaptability and accuracy.

[0027] Furthermore, the transmitting module starts emitting 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 this technical solution, a microcontroller activates the ultrasonic transmission module, and a dedicated ultrasonic ASIC chip is used to implement the device components, reducing hardware costs and improving noise immunity. The use of the ASIC chip improves the overall performance and reliability of the device, enabling stable operation in various environments.

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

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

[0031] To achieve a complete technical effect, the second technical solution of the present invention is an ultrasonic flow measurement method, comprising the following steps:

[0032] Step 1: Using 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 and 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 cross-sectional area S to calculate the fluid flow rate.

[0038] The ultrasonic flow measurement method described in the above technical solution 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 the echo signal amplifier, acquiring and converting the echo signal, adaptively adjusting the first-wave threshold, and measuring the time of flight. The integrated application of these steps improves the automation level and measurement accuracy of flow measurement.

[0039] Furthermore, 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 an expected range.

[0040] In the above technical solution, adaptive adjustment is added to step 2. Specifically, when the echo signal amplitude 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, ensuring stable signal amplitude under different conditions, thereby enhancing the reliability of flow measurement.

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

[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 to step 4. This includes updating the first-wave threshold Vfirst when the correlation value Rxy falls below a preset threshold, and updating the reference wave data if Rxy remains below the preset threshold after multiple updates to the first-wave threshold Vfirst. This adjustment mechanism enhances the device's adaptability to signal changes, improves the accuracy and reliability of flow measurement, and ensures accurate flow data under various conditions.

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

[0045] (1) Through the integrated application of the 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 and ensuring the flexibility and accuracy of signal processing.

[0046] (2) Adaptive adjustment of the echo signal amplifier gain 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, ensuring that reliable flow measurement results can be obtained even in a changing industrial environment.

[0047] (3) By cascading a low-noise amplifier and a variable-gain amplifier, 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 This is the principle diagram of the dual-threshold comparator in the present invention.

[0050] Figure 3 This is a waveform diagram of the 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 solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and exemplary explanations. 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 intended to limit the conditions for the implementation of the present invention. Therefore, they have no technical significance. Any modification of the structure, change in the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose of the present invention.

[0054] Application Overview

[0055] In the field of flow measurement, ultrasonic flowmeters are commonly used to measure fluid velocity and flow rate. Ultrasonic flowmeters calculate flow rate by measuring the difference in propagation time of ultrasonic waves traveling downstream and upstream of the fluid. They are non-invasive and applicable to a wide range of media. However, conventional ultrasonic flowmeters have several drawbacks, such as sensitivity to ambient temperature and transducer status, susceptibility to changes in the medium, and a lack of flexibility and adaptability in signal processing. These issues limit measurement accuracy and the stability of the equipment in complex industrial environments. Therefore, the industry urgently needs an ultrasonic flow measurement 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 achieves high-precision measurement of fluid flow through intelligent signal processing and adaptive regulation. The device includes a first transducer and a second transducer, mounted upstream and downstream of a flow channel, respectively. The transducers are separated by a linear distance L and have an angle θ with the flow channel. The flow channel has a cross-sectional area S, and the fluid velocity is assumed to be v. Alternatively, the first and second transducers can be mounted on the same side of the flow channel, forming a V-shaped ultrasonic flight path.

[0058] The transceiver switching circuit controls the transmission and reception states between the first and second transducers. When the first transducer transmits an ultrasonic wave, the second transducer receives it, recording the time it takes for the ultrasonic wave to propagate from the first to the second transducer. Conversely, when the second transducer transmits an ultrasonic wave, the first transducer receives it, recording the time it takes. The difference between these two times is a key parameter for calculating fluid flow rate.

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

[0060] Before receiving an ultrasonic echo, the dual-threshold comparator selects the first-wave threshold as a comparison benchmark. When the comparator first flips high, it immediately selects the zero-crossing threshold as a comparison benchmark. The comparator's flipping moment then serves as the zero-crossing marker. Based on these zero-crossing markers, the positive / negative zero-crossing timing circuit measures the flight time from ultrasonic emission to a series of positive / negative zero-crossings. Positive zero-crossings correspond to the rising edge of the dual-threshold comparator, while negative zero-crossings correspond to the falling edge.

[0061] The analog-to-digital converter (ADC) operates from the moment the dual-threshold comparator detects the first wave until the dual-threshold comparator outputs the last zero-crossing marker, converting the stable-amplitude ultrasonic echo signal into a digital signal. The received wave sampling data serves as storage for the ADC output data, while the reference wave storage data is pre-set or updated in real time based on the ultrasonic flowmeter's operating status.

[0062] The cross-correlation circuit performs a cross-correlation operation on the sampled data of a single ultrasonic echo and the stored data of the reference wave, outputting the correlation value. A peak detector detects the amplitude of the ultrasonic echo signal to determine whether it is stable near the set target. The microcontroller aggregates the characteristic information of the ultrasonic echo signal and performs information analysis and processing, including the flight time, correlation value, and the peak detector output, to calculate the downstream and upstream flight times of the ultrasonic wave, as well as the time difference between the two.

[0063] The microcontroller determines whether to reset the gain of the variable gain amplifier during power-up initialization of the gain adjustment circuit or when the ultrasonic echo amplitude deviates from the expected value. The microcontroller also determines whether to reset the first-wave threshold adjustment circuit during power-up initialization or when the correlation between the ultrasonic echo and the reference wave falls below the set level. The microcontroller initiates ultrasonic transmission from the transmitter module.

[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, improve noise resistance, and enhance overall performance.

[0067] Please refer to Figure 2 、 Figure 3 In a specific implementation, the dual-threshold comparator operates as follows: Vecho is the 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. Initially, the dual-threshold comparator's threshold is set to the first-wave threshold Vfirst. The ultrasonic echo signal is a series of sinusoidal waves, whose amplitude gradually increases until it reaches a stable amplitude, after which it decays and oscillates. When the ultrasonic echo exceeds the first-wave threshold Vfirst, the comparator outputs its first positive pulse, indicating that the ultrasonic echo has reached the receiver. The dual-threshold comparator then switches to the zero-crossing threshold Vzero. Thereafter, the comparator outputs a positive pulse whenever the ultrasonic echo exceeds the threshold Vzero.

[0068] Please refer to Figure 4The core circuit of the peak detector consists of two parts: a resistor string on the left and a comparator array on the right. The resistor string is connected end to end and ultimately connected between the power supply voltage VDD and ground. The voltage at node 0 is equal to 0.5×VDD, the voltage at node 1 is equal to vpth1, the voltage at node 2 is equal to vpth2, and so on, until the voltage at node 8 is equal to vpth8. The non-inverting 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, until 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, until the output signal of peak comparator 8 is recorded as Vpout8. Vpout1 to Vpout8 are transmitted to the microcontroller, which can easily determine the amplitude of the current ultrasonic echo based on 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 cross-correlation circuit operates as follows: When the dual-threshold comparator outputs a first-wave pulse, indicating that the ultrasonic echo has reached the receiver, the analog-to-digital converter begins sampling the received wave signal and storing the sampled data in a corresponding memory. Sampling continues until the last set zero-crossing point. The reference wave sample data can be pre-stored in the corresponding memory during the flow meter's manufacturing process, or in a dedicated test mode, the received wave at zero flow can be sampled as the corresponding reference wave. The cross-correlation circuit then performs a cross-correlation operation on the ultrasonic echo and the reference wave to determine the correlation value. If the correlation value is between 0.8 and 0.95, the ultrasonic echo and the reference wave are highly similar, indicating that the flow meter's selected first-wave threshold is appropriate. Conversely, if the correlation value is less than 0.8, there is a certain degree of deviation between the ultrasonic echo and the reference wave. This may be due to an improperly set first-wave threshold, requiring the system to reset the threshold. Alternatively, it may be due to changes in transducer characteristics caused by transducer aging or contamination. 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 upstream and downstream of the flow channel respectively. The straight-line distance L between them 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 an ultrasonic wave, the second transducer receives it, recording the time it takes for the ultrasonic wave to propagate from the first to the second transducer. Conversely, when the second transducer transmits an ultrasonic wave, the first transducer receives it, recording the time required. The received ultrasonic echo signal is first amplified by a low-noise amplifier to improve the signal-to-noise ratio. A variable-gain amplifier then further amplifies the signal, stabilizing 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. The flipping moment of the comparator is then used as the zero-crossing point identifier.

[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 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 stable amplitude into a digital signal.

[0077] The cross-correlation operation circuit performs a cross-correlation operation on the sampled data of a primary ultrasonic echo and the stored data of the reference wave, and outputs a 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 output results of the peak detector to calculate the downstream and upstream flight time of the ultrasonic wave and the time difference between the two.

[0079] When the gain adjustment circuit is initialized upon power-up 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.

[0080] When the first wave threshold adjustment circuit is initialized upon power-up, 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 microcontroller activates the ultrasonic emission in the transmitter module. The microcontroller calculates the fluid flow rate using a formula, where K is the flow calibration factor. The entire device can be implemented using discrete components or a dedicated ultrasonic ASIC chip to reduce hardware costs, improve noise immunity, and enhance overall performance.

[0082] The various technical features described in the above exemplary embodiments can be combined arbitrarily. In order 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 The cross-correlation operation circuit is used to perform cross-correlation operation on the sampling data of the ultrasonic echo and the pre-stored reference wave data, and output the correlation value Rxy between the two; A microcontroller, configured to automatically adjust a first wave threshold or update reference wave data according to a comparison result between the correlation value Rxy and a 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 simultaneously detect positive and negative zero-crossing points; Peak detector, 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 ultrasonic echo signal amplitude.

2. An ultrasonic flow metering device according to claim 1, characterized in that: Also includes: A first transducer and a second transducer are installed 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 and second transducers and the flow channel affects the propagation path of the ultrasonic signal and is used to optimize the signal reception 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. The ultrasonic flow metering device according to claim 1, wherein: Also includes: 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. The ultrasonic flow metering device according to claim 1, wherein: Also includes: 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 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 stable amplitude into a digital signal.

5. The ultrasonic flow metering device according to claim 1, wherein: Also includes: 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 stores the preset reference wave storage data or updates it in real time according to the working status of the ultrasonic flowmeter.

6. The ultrasonic flow metering device according to claim 1, characterized in that: Also includes: The transmitting module starts emitting 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. The ultrasonic flow metering device according to 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: Using 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 and 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 cross-sectional area S to calculate the fluid flow rate.

9. The ultrasonic flow measurement method according to claim 8, wherein: 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. The ultrasonic flow measurement method according to claim 8, wherein: In step four, the adaptive adjustment also includes that 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 includes that in step four, when Rxy is still lower than the preset threshold after multiple updates of the first wave threshold Vfirst, the microcontroller controls the reference wave storage data module to update the reference wave data.

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