A low-flow high-precision Doppler acoustic two-way current meter

Abstract

The present invention relates to the technical field of fluid velocimeters, and particularly relates to a low-flow high-precision Doppler acoustic two-way velocimeter. Compared with the prior art, in the present invention, a first electrical signal is generated by a transmitting module and an external signal is simultaneously generated. The external signal generates a reflected signal through the fluid, which is received by a receiving module and converted into an electrical signal. The reflected wave signal is formed by the electrical signal and the local oscillator signal through a second mixer. The reference electrical signal formed by the first electrical signal through a first mixer is compared and calculated by a data processing module to measure the flow velocity and flow direction of the fluid. In the present invention, the frequency of the reference electrical signal is adjusted to 60KHz - 100KHz to avoid the problems that the mixing output is difficult and the filtering is difficult at low flow velocities due to the low frequency of the reference electrical signal, resulting in difficulty in measuring low flow velocities.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid velocimeters, and particularly relates to a low-flow high-precision Doppler acoustic bidirectional velocimeter. Background Art

[0002] An ultrasonic Doppler velocimeter is a flowmeter made based on the principle of the acoustic Doppler effect. It uses an ultrasonic transducer to detect the flow velocity with ultrasonic waves. The measurement point is in front of the probe, without disturbing the flow field, and has the advantages of high measurement accuracy, wide range; it can measure weak flows and strong flows; high resolution, fast response speed; it can measure instantaneous flow velocity and average flow velocity; linear measurement, and the flow velocity calibration curve is not easy to change; there are no mechanical rotating parts, there are no problems of sediment blockage and waterweed entanglement; the probe is strong and durable, not easy to be damaged, and easy to operate.

[0003] For example, the patent with publication number CN104865404A, publication date August 26, 2015, and title "An Acoustic Doppler Flow Velocity Measuring Instrument and Flow Velocity Measuring Method" discloses an acoustic Doppler flow velocity measuring instrument, including a transmitting module, a receiving module, a control circuit, a communication module, and a single-chip microcomputer; the input end of the transmitting module is connected to the corresponding output end of the single-chip microcomputer, and the receiving module is bidirectionally connected to the single-chip microcomputer; the output end of the control circuit is connected to the corresponding input end of the single-chip microcomputer; the communication module is bidirectionally connected to the single-chip microcomputer. It uses a 5MHz measurement signal and calculates the Doppler frequency shift to measure the flow velocity through the autocorrelation algorithm, with low requirements for water particles and a relatively wide measurement range. Currently, Doppler acoustic flow velocimeters for measuring water flow on the market all use a 2 - 5MHz direct mixer to achieve Doppler acoustic flow velocity measurement. The advantages are simple circuit, high stability, and not easy to generate frequency drift, but it is difficult to mix at low flow velocities. It is difficult to output when mixing below 200Hz, the data is inaccurate when the flow velocity is below 2CM, and it is basically impossible to measure at millimeter flow velocities.

[0004] In summary, the existing Doppler flow velocity measuring instruments have the problem that the measurement of the flow velocity of low-flow fluids is inaccurate or difficult to measure and needs to be solved. Summary of the Invention

[0005] To solve the deficiencies in the above-mentioned prior art, the present invention provides a low-flow high-precision Doppler acoustic bidirectional velocimeter, including:

[0006] A transmitting module, the transmitting module is electrically connected to a first mixer, and the transmitting module is used to generate a first electrical signal and an external signal generated by the first electrical signal;

[0007] A receiving module, the receiving module is electrically connected to a second mixer;

[0008] A local oscillator, the local oscillator is electrically connected to the first mixer and the second mixer respectively, and the local oscillator is used to generate a local oscillation electrical signal; and

[0009] A data processing module, the input end of the data processing module is electrically connected to the output ends of the first mixer and the second mixer respectively;

[0010] Wherein, the first mixer is used to mix the first electrical signal and the local oscillation electrical signal to obtain a reference electrical signal with a first frequency, and the first frequency is 60KHz - 100KHz.

[0011] In one embodiment, the transmitting module includes a driving transducer, a transmitting oscillator and a power amplifier. The transmitting oscillator is electrically connected to the driving transducer through the power amplifier on the one hand and to the first mixer on the other hand, and the transmitting oscillator is used for the first electrical signal.

[0012] In one embodiment, the receiving module includes a receiving transducer and a high-frequency amplifier. The receiving transducer is electrically connected to the second mixer through the high-frequency amplifier, and the receiving transducer is used to receive the reflected signal of the external signal and convert it into a second electrical signal.

[0013] In one embodiment, the models of the driving transducer and the receiving transducer are both 5M piezoelectric ceramic transducers.

[0014] In one embodiment, a reference signal preprocessing module is further included, and the first mixer is electrically connected to the data processing module through the reference signal preprocessing module.

[0015] In one embodiment, the reference signal preprocessing module includes a first intermediate frequency filter and a first intermediate frequency amplifier, and the first mixer is electrically connected to the data processing module through the first intermediate frequency filter and the first intermediate frequency amplifier in sequence.

[0016] In one embodiment, a reflected wave signal preprocessing module is further included, and the second mixer is electrically connected to the data processing module through the reflected wave signal preprocessing module.

[0017] In one embodiment, the reflected wave signal preprocessing module includes a second intermediate frequency filter, a second intermediate frequency amplifier, a third intermediate frequency filter and a third intermediate frequency amplifier, and the second mixer is electrically connected to the data processing module through the second intermediate frequency filter, the second intermediate frequency amplifier, the third intermediate frequency filter and the third intermediate frequency amplifier in sequence.

[0018] In one embodiment, the first electrical signal has a second frequency, the local oscillator electrical signal has a third frequency, and the first frequency is the difference frequency between the second frequency and the third frequency.

[0019] In one embodiment, the second frequency is 5 MHz, the third frequency is 4.915 MHz, and the first frequency is 85 KHz.

[0020] Based on the above, compared with the prior art, the low-flow high-precision Doppler acoustic two-way flowmeter provided by the present invention generates a first electrical signal through the transmitting module and simultaneously generates an external signal. The external signal generates a reflected signal through the fluid, which is received by the receiving module and converted into an electrical signal. The reflected wave signal is formed by the second mixer with the local oscillator signal. The reference electrical signal formed by the first mixer with the first electrical signal is compared and calculated by the data processing module to measure the flow rate and flow direction of the fluid. The present invention adjusts the frequency of the reference electrical signal to 60 KHz - 100 KHz to avoid the problems of difficult mixing output and filtering at low flow rates due to the low frequency of the reference electrical signal, which makes it difficult to measure low flow rates.

[0021] Other features and beneficial effects of the present invention will be described in the subsequent specification, and part of them will become obvious from the specification or be understood by implementing the present invention. The objectives and other beneficial effects of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings; in the following description of the positional relationship of the drawings, unless otherwise specified, the direction in which the components are shown in the drawings is taken as the reference.

[0023] Figure 1 It is a schematic diagram of the principle of the low-flow high-precision Doppler acoustic two-way flowmeter provided by the present invention;

[0024] Figure 2 It is a schematic diagram of the principle for further explaining the transmitting module and the receiving module;

[0025] Figure 3 It is a schematic diagram of the principle for further explaining the reference signal processing module and the reflected wave signal processing module;

[0026] Figure 4 It is a schematic diagram of the implementation circuit for the embodiment part.

[0027] Reference Numerals:

[0028] 100 Transmitting Module, 110 Driving Transducer, 120 Transmitting Oscillator

[0029] 130 Power Amplifier, 200 Receiving Module, 210 Receiving Transducer

[0030] 220 High-Frequency Amplifier, 300 Local Oscillator, 400 First Mixer

[0031] 500 Second Mixer, 600 Data Processing Module, 700 Reference Signal Preprocessing Module

[0032] 710 First Intermediate-Frequency Filter, 720 First Intermediate-Frequency Amplifier, 800 Reflected Wave Signal Preprocessing Module

[0033] 810 Second Intermediate-Frequency Filter, 820 Second Intermediate-Frequency Amplifier, 830 Third Intermediate-Frequency Filter

[0034] 840 Third Intermediate-Frequency Amplifier Detailed Implementation Manner

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention; the technical features designed in different implementation manners of the present invention described below can be combined with each other as long as they do not conflict with each other; all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] In the description of the present invention, it should be noted that all terms (including technical terms and scientific terms) used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains, and should not be construed as limiting the present invention; it should be further understood that the terms used in the present invention should be understood as having a meaning consistent with their meanings in the context of this specification and the relevant art, and should not be understood in an idealized or overly formal sense, unless otherwise clearly defined in the present invention.

[0037] The following is illustrated by specific embodiments.

[0038] The present invention provides a low-flow-rate and high-precision Doppler acoustic two-way flowmeter, comprising:

[0039] A transmitting module 100, the transmitting module 100 is electrically connected to a first mixer 400, and the transmitting module 100 is configured to generate a first electrical signal and an external signal generated by the first electrical signal;

[0040] A receiving module 200, the receiving module 200 is electrically connected to a second mixer 500;

[0041] A local oscillator 300, the local oscillator 300 is respectively electrically connected to the first mixer 400 and the second mixer 500, and the local oscillator 300 is used to generate a local oscillator electrical signal; and

[0042] A data processing module 600, an input end of the data processing module 600 is respectively electrically connected to output ends of the first mixer 400 and the second mixer 500;

[0043] Wherein, the first mixer 400 is used to mix the first electrical signal and the local oscillator electrical signal to obtain a reference electrical signal with a first frequency, and the first frequency is 60KHz - 100KHz.

[0044] In specific implementation, as Figure 1 shown, a Doppler acoustic two-way flowmeter includes a transmitting module 100, a receiving module 200, a local oscillator 300 and a data processing module 600. An output end of the local oscillator 300 is respectively connected to input ends of the first mixer 400 and the second mixer 500. The transmitting module 100 is electrically connected to the data processing module 600 through the first mixer 400, and the receiving module 200 is electrically connected to the data processing module 600 through the second mixer 500. The transmitting module 100 generates a first electrical signal. On the one hand, the first electrical signal is input into the first mixer 400, and on the other hand, a related external signal is generated. In this embodiment, the external signal is an ultrasonic signal. A reflected wave generated by the rebound change of the ultrasonic signal through the fluid is received by the receiving module 200. The receiving module 200 processes the reflected wave to form a second electrical signal and transmits it to the second mixer 500. The first mixer 400 mixes the received first electrical signal and the local oscillator electrical signal to form a reference electrical signal with a first frequency of 60KHz - 100KHz and inputs it into the data processing module 600. In this embodiment, a reference electrical signal with a first frequency of 85KHz is taken as an example for illustration. The second mixer 500 mixes the received second electrical signal and the local oscillator electrical signal to form a reflected wave signal and inputs it into the data processing module 600. The data processing module 600 compares and calculates the reference electrical signal and the reflected wave signal to obtain the flow rate.

[0045] In this embodiment, the reference frequency is increased by the mixing frequency, and the reference electrical signal frequency is increased to 85KHz. The local oscillator uses 4.915MHz to generate mixing with the reflected wave to generate an intermediate frequency signal of 85.000KHz when the input flow rate is 0 and 5MHz. The forward flow rate frequency is 85000Hz + x. For every 1Hz increase in the forward flow rate, it increases by approximately 0.152mm. Conversely, for every 1Hz decrease in the reverse flow rate, it increases by 0.152mm. The positive and negative flow rate accuracy can reach 0.152mm. Based on 85000Hz - x (Hz), the magnitude and direction of the reverse flow rate can be calculated.

[0046] Preferably, as Figure 2 and Figure 3 shown, in some embodiments, the transmitting module includes a driving transducer 110, a transmitting oscillator 120, and a power amplifier 130. The transmitting oscillator 120 is electrically connected to the driving transducer 110 through the power amplifier 130 on the one hand and is electrically connected to the first mixer 400 on the other hand. The transmitting oscillator 120 is used for the first electrical signal. The receiving module 200 includes a receiving transducer 210 and a high-frequency amplifier 220. The receiving transducer 210 is electrically connected to the second mixer 500 through the high-frequency amplifier 220. The receiving transducer 210 is used for receiving the reflected signal of the external signal and converting it into a second electrical signal. Wherein the first electrical signal has a second frequency, the local oscillator electrical signal has a third frequency, and the first frequency is the difference frequency between the second frequency and the third frequency.

[0047] Preferably, as Figure 1 shown, in some embodiments, it further includes a reference signal preprocessing module 700 and a reflected wave signal preprocessing module 800. The first mixer 400 is electrically connected to the data processing module 600 through the reference signal preprocessing module 700. The second mixer 500 is electrically connected to the data processing module 600 through the reflected wave signal preprocessing module 800.

[0048] After the reference electrical signal and the reflected wave signal are processed by the intermediate frequency filter and the intermediate frequency amplifier in sequence, specific frequency signals are passed through and amplified, while other frequency signals are filtered out to reduce interference noise, which helps the pulse width output recognition of the subsequent data processing module 600 and improves the accuracy of the flowmeter measurement.

[0049] Specifically, as Figure 3As shown, the reference signal preprocessing module 700 includes a first intermediate frequency filter 710 and a first intermediate frequency amplifier 720. The first mixer 400 is electrically connected to the data processing module 600 through the first intermediate frequency filter 710 and the first intermediate frequency amplifier 720 in sequence. The reflected wave signal preprocessing module 800 includes a second intermediate frequency filter 810, a second intermediate frequency amplifier 820, a third intermediate frequency filter 830, and a third intermediate frequency amplifier 840. The second mixer 500 is electrically connected to the data processing module 600 through the second intermediate frequency filter 810, the second intermediate frequency amplifier 820, the third intermediate frequency filter 830, and the third intermediate frequency amplifier 840 in sequence.

[0050] Specifically, as Figure 4 shown, the implementation circuit diagrams of the modules in this embodiment are provided, where the connections to the data processing module 600 are not specifically shown.

[0051] Preferably, in one embodiment, the first mixer 400 and the second mixer 500 are selected as general oscillator / mixer monolithic integrated circuits of model NE602, which contain a double balanced mixer (DBM), an oscillator, and a voltage regulator. The operating frequency of its double balanced mixer can reach 500 MHz, the oscillation frequency of the oscillator can reach 200 MHz, and the operating temperature range is relatively wide, reaching 0 - 70 °C, with a wide applicable range.

[0052] Preferably, the models of the main components in the above embodiments are as follows. The following selections are for illustrative purposes, and the specific implementation of the present invention is not limited to the following selections:

[0053] The models of the drive transducer 110 and the receiving transducer 210 are 5M piezoelectric ceramic transducers. The model of the power amplifier 130 is D882. The model of the transmitting oscillator 120 is S9014C. The model of the high-frequency amplifier 220 is S9018. The models of the first mixer 400 and the second mixer 500 are NE602. The first intermediate frequency filter 710, the second intermediate frequency filter 810, and the third intermediate frequency filter 830 all adopt LC filters. The models of the first intermediate frequency amplifier 720, the second intermediate frequency amplifier 820, and the third intermediate frequency amplifier 840 are all LMH6624. The model of the data processing module 600 is, for example, STM32F407;

[0054] The sound waves emitted by this device use a 5 MHz frequency for vibration and amplification output, driving the transducer to emit into the water. The receiving transducer receives a 5 Hz reflected signal when the water flow is zero. After high-frequency signal amplification and mixing with the local oscillator signal of 4.915 MHz, an intermediate frequency signal of 85,000 Hz is generated. After two-stage intermediate frequency amplification and an LC intermediate frequency filter circuit, an intermediate frequency signal of 85.000 KHz is output. The intermediate frequency bandwidth is plus or minus 40 KHz, meeting the flow velocity measurement of 7 m / s. According to the characteristics of the LC filter, the signal attenuation of the center frequency is the lowest, so the flow velocity sensitivity is the highest below 2 m / s. The lower the flow velocity, the higher the sensitivity. The received intermediate frequency signal is finally input to the single-chip microcomputer for synchronous comparison with the reference frequency. Another path of the transmitting oscillator is also mixed with the 4.915 MHz local oscillator to generate a reference comparison signal of 85.000 KHz. After the same intermediate frequency amplification and filtering, it is input to the single-chip microcomputer. With this design, the frequency shift caused by temperature drift of the 5 MHz transmitting frequency and the 4.915 MHz local oscillator signal source is automatically tracked and calibrated, and at the same time, the error caused by frequency drift is solved.

[0055] In summary, compared with the prior art, the low-flow-rate and high-precision Doppler acoustic two-way flow velocity meter provided by the present invention generates a first electrical signal through the transmitting module and simultaneously generates an external signal. The external signal generates a reflected signal through the fluid and is received by the receiving module and converted into an electrical signal. The reflected wave signal is formed by mixing with the local oscillator signal through the second mixer. The reference electrical signal formed by mixing the first electrical signal through the first mixer is compared and calculated by the data processing module to measure the flow velocity and flow direction of the fluid. The present invention adjusts the frequency of the reference electrical signal to 60 KHz - 100 KHz to avoid the problems of difficult mixing output and filtering at low flow rates due to the low frequency of the reference electrical signal, which makes it difficult to measure low flow rates. The present invention can be applied to fields such as the measurement of low-speed fluids in chemical engineering or the measurement of the blood flow velocity of animals in biological engineering.

[0056] In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or the background art at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be regarded as a limitation to that claim.

[0057] Although terms such as transmitting module, driving transducer, transmitting oscillator, power amplifier, receiving module, receiving transducer, high-frequency amplifier, local oscillator, first mixer, second mixer, data processing module, reference signal preprocessing module, first intermediate-frequency filter, first intermediate-frequency amplifier, reflected wave signal preprocessing module, second intermediate-frequency filter, second intermediate-frequency amplifier, third intermediate-frequency filter, and third intermediate-frequency amplifier are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention; the terms "first", "second", etc. (if any) in the specification, claims, and the above-mentioned drawings of the embodiments of the present invention are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-flow-rate and high-precision Doppler acoustic two-way flowmeter, characterized in that, it includes: A transmitting module (100), the transmitting module (100) is electrically connected to a first mixer (400), and the transmitting module (100) is used to generate a first electrical signal and an external signal generated by the first electrical signal; The transmitting module includes a driving transducer (110), a transmitting oscillator (120) and a power amplifier (130). The transmitting oscillator (120) is electrically connected to the driving transducer (110) through the power amplifier (130) on the one hand and electrically connected to the first mixer (400) on the other hand. The transmitting oscillator (120) is used to generate the first electrical signal; A receiving module (200), the receiving module (200) is electrically connected to a second mixer (500); A local oscillator (300), the local oscillator (300) is electrically connected to the first mixer (400) and the second mixer (500) respectively, and the local oscillator (300) is used to generate a local oscillator electrical signal; and A data processing module (600), the input end of the data processing module (600) is electrically connected to the output ends of the first mixer (400) and the second mixer (500) respectively; wherein, the first mixer (400) is used to mix the first electrical signal and the local oscillator electrical signal to obtain a reference electrical signal with a first frequency, and the first frequency is 60KHz - 100KHz.

2. The low-flow-rate and high-precision Doppler acoustic two-way flowmeter according to claim 1, characterized in that: The receiving module (200) includes a receiving transducer (210) and a high-frequency amplifier (220). The receiving transducer (210) is electrically connected to the second mixer (500) through the high-frequency amplifier (220). The receiving transducer (210) is used to receive the reflected signal of the external signal and convert it into a second electrical signal.

3. The low-flow-rate and high-precision Doppler acoustic two-way flowmeter according to claim 2, characterized in that: The models of the driving transducer (110) and the receiving transducer (210) are both 5M piezoelectric ceramic transducers.

4. The low-flow-rate and high-precision Doppler acoustic two-way flowmeter according to claim 2, characterized in that: It further includes a reference signal preprocessing module (700), and the first mixer (400) is electrically connected to the data processing module (600) through the reference signal preprocessing module (700).

5. The low-flow-rate and high-precision Doppler acoustic two-way flowmeter according to claim 4, characterized in that: The reference signal preprocessing module (700) includes a first intermediate-frequency filter (710) and a first intermediate-frequency amplifier (720). The first mixer (400) is electrically connected to the data processing module (600) through the first intermediate-frequency filter (710) and the first intermediate-frequency amplifier (720) in sequence.

6. The low-flow-rate and high-precision Doppler acoustic two-way flowmeter according to claim 2, characterized in that: It further includes a reflected wave signal preprocessing module (800), and the second mixer (500) is electrically connected to the data processing module (600) through the reflected wave signal preprocessing module (800).

7. The low-flow high-precision Doppler acoustic two-way current meter according to claim 6, characterized in that: The reflected wave signal preprocessing module (800) includes a second intermediate frequency filter (810), a second intermediate frequency amplifier (820), a third intermediate frequency filter (830) and a third intermediate frequency amplifier (840), and the second mixer (500) is sequentially connected to the data processing module (600) through the second intermediate frequency filter (810), the second intermediate frequency amplifier (820), the third intermediate frequency filter (830) and the third intermediate frequency amplifier (840) for electrical connection.

8. The low-flow high-precision Doppler acoustic two-way current meter according to claim 1, characterized in that: The first electrical signal has a second frequency, the local oscillator electrical signal has a third frequency, and the first frequency is the difference frequency between the second frequency and the third frequency.

9. The low-flow high-precision Doppler acoustic two-way current meter according to claim 8, characterized in that: The second frequency is 5 MHz, the third frequency is 4.915 MHz, and the first frequency is 85 KHz.

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