A differential measurement ultrasonic water meter and a measurement method thereof

Abstract

This invention discloses a differential ultrasonic water meter and its measurement method, belonging to the field of ultrasonic flow measurement technology. It discloses a measuring pipe section, with a first transducer pair installed in a first flow channel, including a first transducer A and a second transducer B arranged opposite each other on the inner wall of the measuring pipe section. The first transducer A and the second transducer B are arranged opposite each other along the upstream to downstream direction of the water flow. A second transducer pair is installed in a second flow channel, including a third transducer C and a fourth transducer D on the inner wall of the measuring pipe section. The third transducer C and the fourth transducer D are arranged opposite each other along the upstream to downstream direction of the water flow and are symmetrically distributed with the first transducer A and the second transducer B on the cross-section of the measuring pipe section. These transducers are used to alternately transmit and receive ultrasonic waves to collect the second downstream propagation time and the second upstream propagation time. The main application is water flow measurement.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic flow measurement technology, specifically to a differential ultrasonic water meter and its measurement method. Background Technology

[0002] Ultrasonic water meters measure flow rate by utilizing the principle that the speed of ultrasonic waves propagating in a fluid is related to the fluid velocity. The time-of-flight method is currently the most widely used technique. The time-of-flight method calculates the flow rate by measuring the time difference between the propagation of ultrasonic waves upstream and downstream.

[0003] However, existing time-difference ultrasonic water meters have significant technical drawbacks: single-channel measurements are susceptible to interference from factors such as ambient temperature changes, electromagnetic noise, and water flow impurities. Temperature changes directly alter the propagation speed of ultrasonic waves in water, leading to measurement deviations; electromagnetic noise and water flow impurities interfere with the transmission and reception of ultrasonic signals, reducing time measurement accuracy and ultimately affecting the long-term stability and metering accuracy of the water meter, making it difficult to meet the requirements of high precision and high reliability metering.

[0004] To address these issues, the industry often employs single-temperature compensation or signal filtering techniques. However, these methods can only alleviate some interference and cannot fundamentally offset multi-source errors. Furthermore, the complex compensation algorithms increase the computational burden on the system, limiting their practicality. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a differential measurement ultrasonic water meter and measurement method. The technical solution adopted is as follows:

[0006] A differential measurement ultrasonic water meter includes a measuring pipe section, a first transducer pair, a second transducer pair, and a signal processing unit. A flow channel is formed within the measuring pipe section for the water to be measured to pass through. The first transducer pair (A, B) is arranged diagonally opposite to each other along the water flow direction to collect the first downstream and upstream propagation times. The second transducer pair (C, D) is arranged opposite to each other and symmetrically distributed across the cross-section with the first transducer pair to collect the second downstream and upstream propagation times. The signal processing unit is electrically connected to both transducer pairs, calculates the water flow velocity after acquiring the propagation time, obtains the compensated velocity through differential calculation, and finally calculates the flow rate.

[0007] By setting up a dual transducer pair and adopting differential measurement, measurement errors caused by interference from temperature, noise, and impurities are effectively offset, thereby improving the measurement accuracy and reliability of ultrasonic water meters.

[0008] The present invention has the following beneficial effects:

[0009] 1. Error cancellation: By utilizing the symmetrical arrangement of dual transducer pairs and the concept of differential measurement, common interferences such as temperature, noise, and impurities on single-channel measurements can be effectively canceled, significantly improving measurement accuracy.

[0010] 2. Improved reliability: The dual redundancy design allows the system to complete measurements through the other channel even if a single transducer or channel fails, thus enhancing the operational reliability of the water meter.

[0011] 3. Simplified Algorithm: The differential operation is performed directly on the speed results, eliminating the need for complex multi-parameter compensation models, which reduces the computational complexity of the signal processing unit and facilitates engineering implementation.

[0012] 4. High adaptability: It is suitable for complex water use scenarios with different water qualities and large temperature variations, and can be widely used in high-precision metering fields such as residential water supply and industrial water use. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the differential measurement ultrasonic water meter of the present invention;

[0014] Figure 2 This is a flowchart of the measurement method of the present invention.

[0015] In the diagram: 1-measuring pipe section, 2-first transducer A, 3-second transducer B, 4-third transducer C, 5-fourth transducer D, 6-signal processing unit. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments, focusing on the methods for obtaining downstream propagation time t1 and upstream propagation time t2, the derivation of flow velocity and the principle of differential error cancellation, to ensure that the technical solution is clear and implementable.

[0017] Example 1:

[0018] Differential Measurement Ultrasonic Water Meter Structure

[0019] like Figure 1 , Figure 2 As shown

[0020] Figure 1 The measuring pipe section 1 is arranged horizontally, with water flowing from left to right. The first transducer A2 is located on the upper left side of the measuring pipe section, and the second transducer B3 is located on the lower right side of the measuring pipe section, arranged diagonally. The third transducer C4 is located on the lower left side of the measuring pipe section, and the fourth transducer C5 is located on the upper right side of the measuring pipe section, symmetrically distributed with the first transducer pair (A, B). The signal processing unit 6 is connected to the four transducers through wires and is used to control the transmission, reception and data processing of signals.

[0021] Figure 2In this method, the measurement process is as follows: collect two sets of propagation times in both directions → calculate two sets of water flow velocities → obtain the compensated velocity through differential calculation → calculate and output the flow rate, forming a complete measurement closed loop to ensure measurement accuracy and reliability.

[0022] This embodiment provides a differential measurement ultrasonic water meter, including a measurement pipe section 1, a first transducer pair, a second transducer pair, and a signal processing unit 6.

[0023] The measuring pipe section 1 is a hollow tubular structure with an internal flow channel. The water to be measured flows along the direction of the flow channel. The inner wall of the pipe section is smooth, which reduces the impact of water flow disturbance on the measurement and ensures water flow stability.

[0024] The first transducer pair includes a first transducer A2 and a second transducer B3, which are disposed opposite to each other on the inner wall of the measuring pipe section 1, arranged in a relative manner from upstream to downstream along the water flow direction. The first transducer A2 and the second transducer B3 can be used alternately as ultrasonic transmitters and receivers to collect the downstream and upstream propagation times of ultrasonic waves.

[0025] The second transducer pair includes a third transducer C4 and a fourth transducer D5, which are arranged opposite each other on the inner wall of the measuring pipe section 1, in a direction from upstream to downstream of the water flow. The third transducer C4 and the fourth transducer D5 are symmetrically distributed with the first transducer pair (A, B) on the cross-section of the measuring pipe section 1 to ensure the consistency and symmetry of the measurement path. They can also alternately transmit and receive ultrasonic waves to collect the second downstream propagation time and the second upstream propagation time.

[0026] The signal processing unit 6 is electrically connected to the first transducer pair (A, B) and the second transducer pair (C, D) respectively, and includes a signal driving module, a time measurement module, a speed calculation module, a differential operation module and a flow calculation module. The time measurement module uses a high-precision timing chip with a timing accuracy of nanosecond level to ensure the measurement accuracy of t1 and t2.

[0027] The signal driving module is used to drive each transducer to emit ultrasonic signals; the time measurement module is used to accurately measure the propagation time of ultrasonic waves (i.e., t1, t2); the velocity calculation module calculates the water flow velocity based on the propagation time; the differential operation module performs differential operation on the calculated water flow velocities of the two transducers to obtain the compensated water flow velocity; and the flow rate calculation module calculates the flow rate based on the compensated water flow velocity and the cross-sectional area of ​​the measuring pipe section 1.

[0028] Example 2:

[0029] Methods for obtaining t1 and t2 and calculation of flow rate

[0030] This embodiment elaborates on the definition, theoretical basis, and actual measurement process of downstream propagation time t1 and upstream propagation time t2. This process is applicable to the first transducer pair (A, B) and the second transducer pair (C, D), and the measurement methods for both are completely consistent.

[0031] 1. Definition and Theoretical Basis: Let the flow velocity of the water in the measuring pipe section be v, the propagation speed of the ultrasonic wave in still water be c, and the straight-line distance between the two transducers in a single transducer pair be L. Then, the effective velocity component of the ultrasonic wave along the water flow direction is v. Based on the time difference method, the theoretical expressions for the downstream time t1 and the upstream time t2 are as follows:

[0032] (1) Downstream propagation time t1: Transducer A is the transmitter and transducer B is the receiver. The ultrasonic wave propagates in the same direction as the water flow and is propelled by the water flow. The propagation speed is c + v. Therefore, the formula for calculating the downstream propagation time t1 is:

[0033] t1 = L / (c + v)

[0034] (2) Backflow propagation time t2: Transducer B acts as the transmitter and transducer A as the receiver. The ultrasonic wave propagates in the opposite direction to the water flow and is hindered by the water flow. The propagation speed is c - v. Therefore, the formula for calculating the backflow propagation time t2 is:

[0035] t2 = L / (c - v)

[0036] 2. Actual Acquisition Method (Hardware Measurement Process): t1 and t2 are not obtained by reverse calculation from theoretical formulas, but are directly measured through the coordinated operation of the water meter's built-in high-precision timing module, signal conditioning module, and transducer. The specific measurement process is as follows:

[0037] (1) Transmission trigger: The signal processing unit (main control unit) of the water meter sends a high-frequency excitation pulse to the transmitting end of the transducer pair (such as A of the first transducer pair) to drive transducer A to emit ultrasonic signals, and at the same time starts the built-in high-precision timer (the timing accuracy reaches the nanosecond level) to start timing.

[0038] (2) Reception and timing stop: After the ultrasonic signal propagates through the water flow in the measuring pipe section, it reaches the receiving end of the transducer pair (such as B of the first transducer pair). Transducer B converts the ultrasonic signal into an electrical signal. After the electrical signal is processed by the signal conditioning circuit (amplified, filtered, and zero-crossing detection), a reception interrupt signal is generated and sent to the main control unit. After receiving the signal, the main control unit controls the high-precision timer to stop counting. The time value recorded by the timer at this time is the downstream propagation time t1 (corresponding to the propagation time from A to B).

[0039] (3) Reverse measurement to obtain t2: After a preset delay (to avoid mutual interference between the two transmitted signals), the main control unit switches the transmitting end and receiving end of the transducer pair, drives transducer B to transmit ultrasonic signals, and transducer A as the receiving end. Repeat the above steps, that is, start the timer, receive the signal, and stop the timer. The time value recorded by the timer at this time is the reverse propagation time t2 (corresponding to the propagation time from B to A).

[0040] (4) Data optimization: In order to resist the interference of electromagnetic noise, water flow disturbance and impurities in the water on the measurement signal and improve the measurement accuracy of t1 and t2, the above-mentioned downstream and upstream measurements are usually performed 3-5 times in succession. The average value of multiple measurement results is taken as the final effective value of t1 and t2 for subsequent flow velocity calculation.

[0041] 3. Flow velocity derivation: Based on the measured t1 and t2, first calculate the time difference between them Δt = t2 - t1. Substituting the theoretical expressions for t1 and t2 into Δt and simplifying, we get:

[0042] Δt = [L / (c - v)] - [L / (c + v)]= 2Lvcosθ / (c 2 - v 2 )

[0043] Because the speed of ultrasonic waves in water, c, is much greater than the speed of water flow, v, therefore v 2 Much smaller than c 2 v can be approximately ignored 2 In this case, the above formula simplifies to:

[0044] Δt ≈ 2Lv / c 2

[0045] The water flow velocity v can be derived from this simplified formula:

[0046] v ≈ (c 2 ·Δt) / 2L

[0047] Example 3:

[0048] Differential error cancellation and measurement methods

[0049] This embodiment provides a measurement method based on the above-mentioned differential measurement ultrasonic water meter, such as... Figure 2 As shown, it includes the following steps:

[0050] S100: Signal processing unit 6 controls the first transducer pair (A, B) to alternately transmit and receive ultrasonic waves, and collects the first downstream propagation time. and the first reverse propagation time Simultaneously, the second transducer pair (C, D) is controlled to alternately transmit and receive ultrasonic waves, and the second downstream propagation time is collected. Second retrograde propagation time The data collection process was strictly performed according to the measurement procedure in Example 2 to ensure... , , , The measurement accuracy.

[0051] S200: The velocity calculation module calculates the first water flow velocity v1 and the second water flow velocity v2 according to the flow velocity derivation formula in Example 2. Taking the first water flow velocity v1 as an example, the calculation formula is: v1≈ (c 2 ·Δt1) / 2L, where The second water flow velocity v2 is calculated similarly. v2≈ (c 2 ·Δt2) / 2L.

[0052] S300: The differential operation module performs differential operations on v1 and v2 to obtain the compensated water flow velocity v_compensation. In this embodiment, the average value of the two is calculated as the compensated water flow velocity, i.e.: v_compensation = (v1 + v2) / 2; if further improvement in accuracy is required, a weighted average calculation can be used. The weights are dynamically adjusted according to the working status (signal strength, signal-to-noise ratio, etc.) of the two transducer pairs. The transducer pair with better working status has a higher weight for the corresponding flow velocity.

[0053] S400: The flow calculation module calculates the flow rate according to the formula Q = v compensation × S, where S is the total cross-sectional area of ​​the measuring pipe section. The cross-sectional area S is pre-calculated based on the inner diameter of the measuring pipe section and stored in the signal processing unit. It outputs the instantaneous flow rate in real time and accumulates the total flow rate.

[0054] The differential measurement ultrasonic water meter and method provided by this invention, through a differential measurement design with dual transducer pairs, effectively offsets measurement errors caused by interference factors such as temperature, noise, and impurities, significantly improving the measurement accuracy and long-term operational reliability of the ultrasonic water meter. This water meter has a simple structure, concise algorithm, and is easy to implement in engineering. It can be widely used in scenarios requiring high-precision flow measurement, such as residential water use, industrial water use, and municipal water supply, and has good industrial application prospects and market value.

Claims

1. A differential ultrasonic water meter, characterized in that, include: The measuring pipe section has a dual flow channel formed within it to accommodate the water flow to be measured; A first pair of transducers is installed in the first flow channel, including a first transducer A and a second transducer B which are disposed opposite to each other on the inner wall of the measuring pipe section. The first transducer A and the second transducer B are arranged opposite to each other in the upstream to downstream direction of the water flow direction, and are used to alternately transmit and receive ultrasonic waves to collect the first downstream propagation time and the first upstream propagation time. A second pair of transducers is installed in the second flow channel, including a third transducer C and a fourth transducer D disposed opposite to each other on the inner wall of the measuring pipe section. The third transducer C and the fourth transducer D are arranged opposite to each other in the upstream to downstream direction of the water flow direction, and are symmetrically distributed with the first pair of transducers (A, B) on the cross section of the measuring pipe section. They are used to alternately transmit and receive ultrasonic waves to collect the second downstream propagation time and the second upstream propagation time. A signal processing unit is electrically connected to the first transducer pair (A, B) and the second transducer pair (C, D), respectively, and the signal processing unit is configured to: The first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time are obtained respectively. The first water flow velocity is calculated based on the first downstream propagation time and the first upstream propagation time. The second water flow velocity is calculated based on the second downstream propagation time and the second upstream propagation time. Perform a difference operation on the first water flow velocity and the second water flow velocity to obtain the compensated water flow velocity; The flow rate of the water to be measured is calculated based on the compensated water flow velocity and the cross-sectional area of ​​the measuring pipe section.

2. The differential measurement ultrasonic water meter according to claim 1, characterized in that, The signal processing unit performs a differential operation on the first water flow velocity and the second water flow velocity as follows: The average of the first water flow velocity and the second water flow velocity is calculated as the compensated water flow velocity; The weighted average of the first water flow velocity and the second water flow velocity is calculated as the compensated water flow velocity, wherein the weight of the weighted average is determined based on the installation location, operating status or environmental parameters of the first transducer pair and / or the second transducer pair.

3. The differential measurement ultrasonic water meter according to claim 1, characterized in that, The signal processing unit is further configured to: The operating status of the first transducer pair and the second transducer pair are detected respectively, and the operating status includes signal strength, signal-to-noise ratio or reception success rate; When the operating state of the first transducer pair is better than that of the second transducer pair, the weight of the first water flow velocity is increased; when the operating state of the second transducer pair is better than that of the first transducer pair, the weight of the second water flow velocity is increased.

4. A differential ultrasonic water meter according to claim 1, characterized in that, The signal processing unit is further configured to: Collect ambient temperature parameters; Preliminary temperature compensation is performed on the first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time based on the ambient temperature parameters. The propagation time after preliminary temperature compensation is differentially calculated to obtain the compensated water flow velocity.

5. A measurement method based on the differential measurement ultrasonic water meter according to any one of claims 1-4, characterized in that, Includes the following steps: S100: The first downstream propagation time and the first upstream propagation time are collected through the first transducer pair (A, B); the second downstream propagation time and the second upstream propagation time are collected through the second transducer pair (C, D); S200: The first water flow velocity is calculated based on the first downstream propagation time and the first upstream propagation time; The second water flow velocity is calculated based on the second downstream propagation time and the second upstream propagation time. S300: Perform a differential calculation on the first water flow velocity and the second water flow velocity to obtain the compensated water flow velocity; S400: The flow rate of the water to be measured is calculated based on the compensated water flow velocity and the cross-sectional area of ​​the measuring pipe section.

6. The measurement method according to claim 5, characterized in that, In step S300, the difference operation is to calculate the average or weighted average of the first water flow velocity and the second water flow velocity.

7. The measurement method according to claim 5, characterized in that, The steps preceding step S100 also include: S050: Collects ambient temperature parameters; In step S200, after preliminary temperature compensation is performed on the first downstream propagation time, the first upstream propagation time, the second downstream propagation time, and the second upstream propagation time based on the ambient temperature parameters, the first water flow velocity and the second water flow velocity are then calculated.

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