Detection device for gas flow in pipeline

Abstract

The invention provides a device for detecting gas flow in a pipeline. The device for detecting the flow of the gas in the pipeline comprises an ultrasonic transmitter which is configured to generate a first ultrasonic signal when a high-low level pulse signal with a preset frequency is applied; the ultrasonic receiver is configured to receive the second ultrasonic signal and convert the second ultrasonic signal into an amplitude-modulated carrier electric signal with corresponding amplitude and frequency; the input end of the signal demodulation circuit is connected with the ultrasonic receiver, and the signal demodulation circuit is configured to process the input amplitude modulation carrier electric signal so as to output a Karman vortex street pulse signal with a complete waveform; and the data processing module is connected with the output end of the signal demodulation circuit and is configured to obtain the pulse frequency of the Karman vortex street pulse signal, the width of the spoiler rod and the sectional area of the pipeline so as to determine the flow of the gas. According to the device for detecting the flow of the gas in the pipeline, the flow of the gas in the pipeline can be detected based on the Karman vortex street phenomenon of fluid mechanics, and people can conveniently know the flowing condition of the gas in the pipeline.

Description

Technical Field

[0001] The invention relates to the field of gas detection, and in particular to a device for detecting gas flow in a pipeline. Background Art

[0002] With the development of society and the continuous improvement of people's living standards, various household appliances have become an indispensable part of people's daily lives. For example, air conditioners can adjust the temperature of the indoor environment where people live, and range hoods can help people exhaust the fumes generated in the kitchen. For these household appliances with pipelines, it is very important to monitor the gas flow inside the pipelines. Because the gas flow in the pipeline can often reflect whether the operation of the household appliance itself is normal, it can help people accurately understand the actual situation of the household appliance. However, the gas flow rate in the pipelines of these household appliances is often large. At present, it is very difficult to detect the flow of gas inside these pipelines, which makes it difficult for people to accurately understand the use of household appliances. Summary of the invention

[0003] One purpose of the present invention is to detect the flow rate of gas in a pipeline based on the Karman vortex street phenomenon of fluid mechanics.

[0004] A further object of the present invention is to improve the accuracy of detecting the gas flow in the pipeline and monitor the gas flow in the pipeline in real time.

[0005] In particular, the present invention provides a device for detecting the gas flow in a pipeline, comprising: an ultrasonic transmitter and an ultrasonic receiver, which are relatively arranged on the inner wall of the pipeline, and a spoiler rod perpendicular to the flow direction of the gas is arranged between the ultrasonic transmitter and the ultrasonic receiver, the ultrasonic transmitter is configured to generate a first ultrasonic signal when a high and low level pulse signal of a preset frequency is applied, and the ultrasonic receiver is configured to receive a second ultrasonic signal and convert it into an amplitude modulated carrier electrical signal corresponding to the amplitude and frequency, wherein the second ultrasonic signal is affected by the gas that generates a Karman vortex street phenomenon when passing through the spoiler rod; a signal demodulation circuit, whose input end is connected to the ultrasonic receiver, and is configured to process the input amplitude modulated carrier electrical signal to output a Karman vortex street pulse signal with a complete waveform; and a data processing module, which is connected to the output end of the signal demodulation circuit, and is configured to obtain the pulse frequency of the Karman vortex street pulse signal, the width of the spoiler rod, and the cross-sectional area of ​​the pipeline to determine the gas flow.

[0006] Optionally, the signal demodulation circuit includes: a preprocessing circuit configured to preprocess the amplitude modulated carrier electrical signal; an envelope detector configured to perform envelope detection on the preprocessed amplitude modulated carrier electrical signal to extract the envelope signal; and a voltage comparator configured to output the input envelope signal as a Karman vortex street pulse signal with a complete waveform.

[0007] Optionally, the preprocessing circuit includes: a voltage follower, a second-order active low-pass filter and an in-phase proportional amplifier connected in sequence, and the ultrasonic receiver is connected to the voltage follower, and the in-phase proportional amplifier is connected to the envelope detector.

[0008] Optionally, the voltage follower is configured to perform impedance transformation on the input amplitude modulated carrier electrical signal to reduce distortion.

[0009] Optionally, the second-order active low-pass filter is configured to perform second-order active low-pass filtering on the amplitude modulated carrier electrical signal, wherein the cut-off frequency is set to a preset frequency.

[0010] Optionally, the in-phase proportional amplifier is configured to perform in-phase proportional amplification on the amplitude modulated carrier electrical signal, and the in-phase proportional amplifier includes a first amplifier and a second amplifier to perform two-stage amplification on the amplitude modulated carrier electrical signal.

[0011] Optionally, the data processing module is further configured to determine the flow rate of the gas according to the pulse frequency and width, and determine the flow rate according to the flow rate and cross-sectional area.

[0012] Optionally, the data processing module is further configured to: calculate the flow velocity using the formula V=f*b / Sr, where V is the flow velocity, f is the pulse frequency, b is the width, and Sr is the Strouhal number; calculate the flow rate using the formula Q=V*S, where Q is the flow rate and S is the cross-sectional area.

[0013] Optionally, the data processing module is further configured to count the rising edge or falling edge of the Karman vortex pulse signal to obtain the pulse frequency.

[0014] Optionally, the device for detecting the gas flow in the pipeline further includes: a pulse generating circuit connected to the ultrasonic transmitter and configured to generate high and low level pulse signals.

[0015] The invention discloses a detection device for gas flow in a pipeline, comprising: an ultrasonic transmitter and an ultrasonic receiver, which are arranged on the inner wall of the pipeline relative to each other, and a spoiler rod perpendicular to the flow direction of the gas is arranged between the ultrasonic transmitter and the ultrasonic receiver, the ultrasonic transmitter is configured to generate a first ultrasonic signal when a high-low level pulse signal of a preset frequency is applied, and the ultrasonic receiver is configured to receive a second ultrasonic signal and convert it into an amplitude modulated carrier electric signal corresponding to the amplitude and frequency, wherein the second ultrasonic signal is affected by the gas that generates a Karman vortex street phenomenon when passing through the spoiler rod; a signal demodulation circuit, whose input end is connected to the ultrasonic receiver and is configured to process the input amplitude modulated carrier electric signal to output a Karman vortex street pulse signal with a complete waveform; and a data processing module, which is connected to the output end of the signal demodulation circuit and is configured to obtain the pulse frequency of the Karman vortex street pulse signal, the width of the spoiler rod and the cross-sectional area of ​​the pipeline to determine the flow of the gas, and can realize the flow detection of the gas in the pipeline based on the Karman vortex street phenomenon of fluid mechanics, so that people can understand the flow of the gas inside the pipeline.

[0016] Furthermore, in the detection device for gas flow in a pipeline of the present invention, the signal demodulation circuit includes: a preprocessing circuit, configured to preprocess an amplitude modulated carrier electrical signal; an envelope detector, configured to perform envelope detection on the preprocessed amplitude modulated carrier electrical signal to extract an envelope signal; and a voltage comparator, configured to output the input envelope signal as a Karman vortex street pulse signal with a complete waveform, and the data processing module is further configured to: count the rising edge or the falling edge of the Karman vortex street pulse signal to obtain the pulse frequency; calculate the flow rate using the formula V=f*b / Sr, wherein V is the flow rate, f is the pulse frequency, b is the width, and Sr is the Strouhal number; calculate the flow rate using the formula Q=V*S, wherein Q is the flow rate and S is the cross-sectional area, which can effectively improve the accuracy of detecting the gas flow in the pipeline, and can monitor the gas flow in the pipeline in real time, thereby facilitating users to understand whether the operation of household appliances such as range hoods themselves is normal.

[0017] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0019] Figure 1 is a schematic block diagram of a device for detecting gas flow in a pipeline according to an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of the internal structure of a pipeline in a device for detecting gas flow in a pipeline according to an embodiment of the present invention;

[0021] Figure 3 is a schematic block diagram of a device for detecting gas flow in a pipeline according to another embodiment of the present invention;

[0022] Figure 4 is a schematic diagram of a pulse generating circuit and an ultrasonic transmitter in a device for detecting gas flow in a pipeline according to an embodiment of the present invention;

[0023] Figure 5 is a schematic diagram of an ultrasonic receiver and a signal demodulation circuit in a device for detecting gas flow in a pipeline according to an embodiment of the present invention;

[0024] Figure 6 is a waveform diagram of high and low level pulse signals generated by a pulse generating circuit in a device for detecting gas flow in a pipeline according to an embodiment of the present invention;

[0025] Figure 7 is a waveform diagram of an amplitude modulated carrier electrical signal preprocessed by a preprocessing circuit in a device for detecting gas flow in a pipeline according to an embodiment of the present invention;

[0026] Figure 8 is a waveform diagram of an envelope signal extracted by an envelope detector in a device for detecting gas flow in a pipeline according to an embodiment of the present invention;

[0027] Fig. 9 It is a waveform diagram of a Karman vortex pulse signal output by a voltage comparator in a device for detecting gas flow in a pipeline according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present embodiment first provides a device 200 for detecting the gas flow in a pipeline, wherein the pipeline 100 may be an exhaust pipeline of an air conditioner or a smoke exhaust pipeline of a range hood. Since the gas flow rate in these pipelines 100 is often relatively large, it is currently very difficult to detect the flow of gas inside these pipelines 100. The device 200 for detecting the gas flow in a pipeline of the present embodiment can solve this problem and can detect the flow of gas in the pipeline 100 based on the Karman vortex street phenomenon in fluid mechanics, thereby facilitating people to understand the flow of gas inside the pipeline 100.

[0029] Figure 1 is a schematic block diagram of a device 200 for detecting gas flow in a pipeline according to an embodiment of the present invention. Figure 2 FIG. 2 is a schematic diagram of the internal structure of a pipeline 100 in a device 200 for detecting gas flow in a pipeline according to an embodiment of the present invention. Figure 1 As shown, the device 200 for detecting the gas flow in a pipeline may generally include: an ultrasonic transmitter 110 and an ultrasonic receiver 120 , a signal demodulation circuit 220 and a data processing module 230 .

[0030] Specifically, Figure 2 FIG. 1 is a schematic cross-sectional view of a pipeline 100, in which gas flows in a direction perpendicular to the cross-sectional view. Figure 2 As shown, the ultrasonic transmitter 110 and the ultrasonic receiver 120 can be arranged on the inner wall of the pipeline 100 relatively. Among them, the ultrasonic transmitter 110 can generate an ultrasonic signal and transmit it. The ultrasonic receiver 120 can receive the ultrasonic signal reflected from the object and convert it into an electrical signal. Both the ultrasonic transmitter 110 and the ultrasonic receiver 120 can use ultrasonic transducers. The working principle of the ultrasonic transducer mainly depends on the characteristics of ultrasonic waves and the piezoelectric effect. It has the advantages of simple structure and wide application, and is suitable for the detection device of the gas flow in the pipeline of this embodiment.

[0031] The ultrasonic transmitter 110 and the ultrasonic receiver 120 can generally use piezoelectric materials, such as quartz crystal or lead titanium zirconate. When an external voltage is applied to the ultrasonic transmitter 110, the piezoelectric material will deform, thereby generating an ultrasonic signal. When the ultrasonic wave encounters an object, part of the energy will be reflected back and received by the ultrasonic receiver 120. The piezoelectric material in the ultrasonic receiver 120 will generate an electric charge, thereby converting the ultrasonic signal into an electrical signal.

[0032] The ultrasonic transmitter 110 and the ultrasonic receiver 120 in this embodiment can be composed of one or more piezoelectric chips. The shape of the chip can be circular, rectangular or other shapes, which can be selected according to different application requirements. An impedance matching layer can be coated on the surface of the chip to improve the energy transmission efficiency. It should be noted that ultrasound is a sound wave with a frequency higher than the human hearing range, and its frequency is usually between 20kHz and 1MHz.

[0033] A spoiler rod 130 perpendicular to the flow direction of the gas is provided between the ultrasonic transmitter 110 and the ultrasonic receiver 120. When the gas flows to the spoiler rod 130 in the pipeline 100, the Karman vortex street phenomenon occurs. The Karman vortex street phenomenon refers to the fact that when a steady flow under certain conditions bypasses certain objects, two rows of line vortices with opposite rotation directions and regular arrangement will periodically fall off on both sides of the object. At the beginning, the two rows of line vortices maintain their own movement forward, and then they interfere with each other, attract each other, and the interference becomes greater and greater, forming a nonlinear Karman vortex street. As an important phenomenon studied in viscous incompressible fluid dynamics, the Karman vortex street can often be encountered in nature. For example, water flowing over bridge piers, wind blowing over high towers, chimneys, power lines, etc. will form a Karman vortex street.

[0034] In a specific embodiment, the ultrasonic transmitter 110 may be configured to generate a first ultrasonic signal when a high-low level pulse signal of a preset frequency is applied. The preset frequency may be 200 kHz. In other words, a high-low level pulse signal of 200 kHz may be applied to the ultrasonic transmitter 110 so that the ultrasonic transmitter 110 generates and transmits the first ultrasonic signal. The above-mentioned specific value of the preset frequency of 200 kHz is only an example and is not intended to limit the present invention. In other embodiments, it may be set to other values ​​according to actual conditions.

[0035] The ultrasonic receiver 120 can be configured to receive the second ultrasonic signal and convert it into an amplitude modulated carrier electrical signal corresponding to the amplitude and frequency. Since the ultrasonic transmitter 110 and the ultrasonic receiver 120 are arranged opposite to each other, and the spoiler rod 130 is arranged between the two, the Karman vortex street phenomenon will occur when the gas flows to the spoiler rod 130 in the pipeline 100. Therefore, the second ultrasonic signal received by the ultrasonic receiver 120 is affected by the gas that generates the Karman vortex street phenomenon when passing through the spoiler rod 130. In addition, the ultrasonic receiver 120 converts the second ultrasonic signal into an amplitude modulated carrier electrical signal corresponding to the amplitude and frequency, which can ensure that the envelope signal extracted subsequently can reflect the size of the gas flow.

[0036] The input end of the signal demodulation circuit 220 is connected to the ultrasonic receiver 120, and is configured to process the input amplitude modulated carrier electrical signal to output a Karman vortex street pulse signal with a complete waveform. The data processing module 230 is connected to the output end of the signal demodulation circuit 220, and is configured to obtain the pulse frequency of the Karman vortex street pulse signal, the width of the spoiler rod 130, and the cross-sectional area of ​​the pipeline 100 to determine the flow rate of the gas.

[0037] In summary, the detection device 200 for gas flow in a pipeline of the present embodiment comprises: an ultrasonic transmitter 110 and an ultrasonic receiver 120, which are arranged on the inner wall of the pipeline 100 relative to each other, and a spoiler rod 130 perpendicular to the flow direction of the gas is arranged between the ultrasonic transmitter 110 and the ultrasonic receiver 120, the ultrasonic transmitter 110 is configured to generate a first ultrasonic signal when a high and low level pulse signal of a preset frequency is applied, and the ultrasonic receiver 120 is configured to receive a second ultrasonic signal and convert it into an amplitude modulated carrier electrical signal corresponding to the amplitude and frequency, wherein the second ultrasonic signal is subjected to the spoiler rod 130 when passing through the spoiler rod 130. The gas influence that produces Karman vortex street phenomenon; the signal demodulation circuit 220, whose input end is connected to the ultrasonic receiver 120, is configured to process the input amplitude modulated carrier electrical signal to output a Karman vortex street pulse signal with a complete waveform; and the data processing module 230, which is connected to the output end of the signal demodulation circuit 220, is configured to obtain the pulse frequency of the Karman vortex street pulse signal, the width of the spoiler rod 130 and the cross-sectional area of ​​the pipeline 100 to determine the flow rate of the gas, and can realize the flow detection of the gas in the pipeline 100 based on the Karman vortex street phenomenon of fluid mechanics, so that people can understand the flow of the gas inside the pipeline 100.

[0038] In some optional embodiments, the device 200 for detecting gas flow in a pipeline can achieve a higher technical effect by further optimizing and configuring. Figure 3 FIG. 2 is a schematic block diagram of a device 200 for detecting gas flow in a pipeline according to another embodiment of the present invention. Figure 3 As shown, based on the previous embodiment, the device 200 for detecting the gas flow in a pipeline of this embodiment can flexibly add the following settings: a pulse generating circuit 210 .

[0039] Figure 4 FIG. 2 is a schematic diagram of a pulse generating circuit 210 and an ultrasonic transmitter 110 in a device 200 for detecting gas flow in a pipeline according to an embodiment of the present invention. Figure 3 and Figure 4 As shown, the pulse generating circuit 210 is connected to the ultrasonic transmitter 110 and is configured to generate high and low level pulse signals. When the high and low level pulse signals are applied to the ultrasonic transmitter 110, the ultrasonic transmitter 110 generates a first ultrasonic signal and transmits it. Specifically, Figure 4 As shown, the pulse generating circuit 210 may include the following components: C61, C3, C4, C5, C6, C62, R1, R2, and R41, where C is a capacitor and R is a resistor.

[0040] Figure 5 FIG. 2 is a schematic diagram of an ultrasonic receiver 120 and a signal demodulation circuit 220 in a device 200 for detecting gas flow in a pipeline according to an embodiment of the present invention. Figure 3 and Figure 5 As shown, the signal demodulation circuit 220 of the detection device 200 for the gas flow in the pipeline of this embodiment may include: a preprocessing circuit 221, an envelope detector 170 and a voltage comparator 180. Among them, the preprocessing circuit 221 can be configured to preprocess the amplitude modulated carrier electrical signal. The envelope detector 170 can be configured to perform envelope detection on the preprocessed amplitude modulated carrier electrical signal to extract the envelope signal. The voltage comparator 180 can be configured to output the input envelope signal as a Karman vortex street pulse signal with a complete waveform.

[0041] It should be noted that the preprocessing circuit 221 preprocesses the amplitude modulated carrier electrical signal to further ensure that the subsequently extracted envelope signal can reflect the size of the gas flow. The output waveform of the Karman vortex pulse signal can also ensure that the subsequently acquired pulse frequency is relatively accurate, so as to finally calculate the accurate gas flow.

[0042] In a preferred embodiment, Figure 5 As shown, the preprocessing circuit 221 may include: a voltage follower 140 , a second-order active low-pass filter 150 and an in-phase proportional amplifier 160 connected in sequence. In addition, the ultrasonic receiver 120 is connected to the voltage follower 140 , and the in-phase proportional amplifier 160 is connected to the envelope detector 170 .

[0043] Among them, the voltage follower 140 can be configured to perform impedance transformation on the input amplitude modulated carrier electrical signal to reduce distortion. The second-order active low-pass filter 150 can be configured to perform second-order active low-pass filtering on the amplitude modulated carrier electrical signal, wherein the cut-off frequency is set to a preset frequency. The in-phase proportional amplifier 160 can be configured to perform in-phase proportional amplification on the amplitude modulated carrier electrical signal. And the in-phase proportional amplifier 160 may include a first amplifier 161 and a second amplifier 162 to perform two-stage amplification on the amplitude modulated carrier electrical signal. That is, after the ultrasonic receiver 120 outputs the amplitude modulated carrier electrical signal, the amplitude modulated carrier electrical signal undergoes impedance transformation, second-order active low-pass filtering, and in-phase proportional amplification in sequence.

[0044] Figure 6 is a waveform diagram of high and low level pulse signals generated by a pulse generating circuit 210 in a device 200 for detecting gas flow in a pipeline according to an embodiment of the present invention, Figure 7 is a waveform diagram of an amplitude modulated carrier electrical signal preprocessed by a preprocessing circuit 221 in a device for detecting gas flow in a pipeline 200 according to an embodiment of the present invention, Figure 8 is a waveform diagram of an envelope signal extracted by an envelope detector 170 in a device 200 for detecting gas flow in a pipeline according to an embodiment of the present invention. Fig. 94 is a waveform diagram of a Karman vortex pulse signal output by a voltage comparator 180 in a device 200 for detecting gas flow in a pipeline according to an embodiment of the present invention.

[0045] Figures 6 to 9 The waveforms can be detected by an oscilloscope, which transforms the invisible electrical signals into visible images, so that people can understand the change process of the signals. In a specific embodiment, a Tektronix oscilloscope with a bandwidth of 500Mhz can be used for detection. The specific types of the above oscilloscopes are only examples, and are not intended to limit the present invention. In other embodiments, it can be set according to actual conditions.

[0046] Specifically, the voltage follower 140 in the preprocessing circuit 221 is a feedback circuit, and its basic principle is to use negative feedback to achieve the matching between the output voltage and the input voltage, and its output voltage will change with the change of the input voltage. The voltage follower 140 is composed of two basic components: an amplifier and a feedback circuit. The amplifier can be any type of amplifier, such as a common-emitter amplifier, a common-base amplifier or a common-collector amplifier. The function of the feedback circuit is to compare the output signal of the amplifier with the input signal, and feed back the difference to the input terminal of the amplifier to maintain the stability of the output voltage. The voltage follower 140 in this embodiment plays the role of impedance transformation and reducing distortion.

[0047] The second-order active filter 150 in the preprocessing circuit 221 is a basic circuit commonly used in signal detection and transmission systems, and is also a basic component unit of a high-order filter. The second order of the second-order active filter 150 is to make the output voltage drop at a faster rate in the high frequency band to improve the filtering effect. An RC low-pass filter link is added, which has a better filtering effect than the first-order low-pass filter. In addition, the second-order active filter 150 allows signals below the cut-off frequency to pass. In a specific embodiment, the cut-off frequency is set to a preset frequency.

[0048] The in-phase proportional amplifier 160 in the preprocessing circuit 221 is an analog circuit that can amplify the input signal into an output signal and can provide a larger signal amplitude. The in-phase proportional amplifier 160 can be used to enhance the amplitude of the signal so that the signal can be transmitted over a longer distance, thereby improving the reliability of the signal. When the amplitude of the input signal of the in-phase proportional amplifier 160 increases, the amplitude of the output signal will also increase, and the two are proportional. The in-phase proportional amplifier 160 has good stability, the gain can be adjusted by the adjustment circuit, and it also has the advantages of low cost, low distortion characteristics and energy-saving characteristics. The in-phase proportional amplifier 160 in this embodiment may include a first amplifier 161 and a second amplifier 162 to perform a two-stage amplification of the amplitude modulated carrier electrical signal.

[0049] The envelope detector 170 can convert the high-frequency signal into a low-frequency signal. When the high-frequency signal passes through the half-wave or full-wave rectifier, its negative half cycle is truncated, leaving only the positive half cycle, thereby reducing the frequency of the signal to half or double the original frequency. Subsequently, the low-pass filter will filter out the high-frequency part, leaving only the low-frequency envelope signal, thus realizing the extraction of the envelope signal.

[0050] The voltage comparator 180 is a circuit for distinguishing and comparing input signals and is a basic unit circuit for forming a non-sinusoidal wave generating circuit. The voltage comparator 180 can be used as an interface between analog circuits and digital circuits, and can also be used as a waveform generating and transforming circuit. In this embodiment, the voltage comparator 180 can be used to convert a sine wave into a square wave or rectangular wave of the same frequency.

[0051] like Figure 5 As shown, the voltage follower 140 may include the following components: C64, R10, R4, U5B. The second-order active low-pass filter 150 may include the following components: R42, R43, R6, R9, R3, C79, C80, C63, C14, C16, C10, C12, C77, U5A. The first amplifier 161 of the in-phase proportional amplifier 160 may include the following components: R7, R5, R12, R51, C11, C13, C15, C17, C78, ​​U6A. The second amplifier 162 of the in-phase proportional amplifier 160 may include the following components: R8, R53, R52, R13, R35, U6B. The envelope detector 170 may include the following components: R55, R18, R19, R14, R57, R54, R56, C67, C68, C26, C18, C19, C23, D1, U7A. The voltage comparator 180 may include the following components: R15, R20, R17, R16, C21, C25, C20, C24, C27, C22, U8A. Among them, C represents a capacitor, R represents a resistor, D represents a diode, and U5B, U5A, U6A, U6B, U7A, and U8A are operational amplifiers.

[0052] It should be emphasized that preprocessing the amplitude modulated carrier electrical signal can further ensure that the subsequently extracted envelope signal can reflect the size of the gas flow rate. The output of the Karman vortex pulse signal with a complete waveform can also ensure that the subsequently acquired pulse frequency is relatively accurate, so that the accurate gas flow rate can be finally calculated.

[0053] The data processing module 230 in this embodiment can also be configured to count the rising edge or falling edge of the Karman vortex street pulse signal to obtain the pulse frequency. In a specific embodiment, the data processing module 230 can be a single-chip microcomputer. After the voltage comparator 180 outputs the Karman vortex street pulse signal with a complete waveform, the single-chip microcomputer can be used to count the rising edge or falling edge of the Karman vortex street pulse signal to obtain the pulse frequency.

[0054] The data processing module 230 can also be configured to determine the flow rate of the gas according to the pulse frequency and width, and determine the flow rate according to the flow rate and cross-sectional area. Figure 1 As shown, the width of the spoiler bar 130 may be b, the inner radius of the pipe 100 may be r, and the cross-sectional area of ​​the pipe 100 may be π*r 2 That is to say, the flow velocity of the gas in the pipeline 100 may be determined first, and then the flow rate of the gas may be determined.

[0055] Further, the data processing module 230 can also be configured to: calculate the gas flow rate using the formula V=f*b / Sr, where V is the flow rate, f is the pulse frequency, b is the width, and Sr is the Strouhal number; calculate the gas flow rate using the formula Q=V*S, where Q is the flow rate and S is the cross-sectional area. In the case where the data processing module 230 is a single-chip microcomputer, after the single-chip microcomputer is used to count the rising edge or falling edge of the Karman vortex pulse signal to obtain the pulse frequency, the specific calculation process of calculating the gas flow rate and flow rate using the formula can also be performed by the single-chip microcomputer.

[0056] The Strouhal number is a similarity criterion introduced when discussing physical similarity and modeling in fluid mechanics, and its physical meaning is the ratio of the inertial force of unsteady motion to the inertial force. The Strouhal number in this embodiment can be set to 0.21. In a specific embodiment, the pipeline 100 can be a DN100 pipeline, and the inner diameter can be 95mm, that is, r is 95 / 2, so the cross-sectional area S of the pipeline 100 is 0.007088. The specific type and value of the above-mentioned pipeline 100 are also only for example, and are not intended to limit the present invention. In some other embodiments, it can also be set to other types and values ​​according to actual conditions.

[0057] In summary, the detection device 200 for gas flow in a pipeline of the present embodiment, the signal demodulation circuit 220 includes: a preprocessing circuit 221, configured to preprocess the amplitude modulated carrier electrical signal; an envelope detector 170, configured to perform envelope detection on the preprocessed amplitude modulated carrier electrical signal to extract the envelope signal; and a voltage comparator 180, configured to output the input envelope signal as a Karman vortex street pulse signal with a complete waveform, and the data processing module 230 is further configured to: count the rising edge or the falling edge of the Karman vortex street pulse signal to obtain the pulse frequency; calculate the flow rate using the formula V=f*b / Sr, where V is the flow rate, f is the pulse frequency, b is the width, and Sr is the Strouhal number; calculate the flow rate using the formula Q=V*S, where Q is the flow rate and S is the cross-sectional area, which can effectively improve the accuracy of detecting the gas flow in the pipeline 100, and can monitor the gas flow in the pipeline 100 in real time, so as to facilitate users to understand whether the operation of household appliances such as range hoods is normal.

[0058] After determining whether the operation of household appliances such as range hoods is normal according to the gas flow inside the pipe 100, specifically, according to the gas flow inside the pipe 100, the user can be reminded in a targeted manner. For example, if the gas flow in the exhaust pipe of the range hood is small, it means that there may be a blockage in the exhaust pipe. Fumes that cannot be discharged in time will not only make the kitchen greasy, but may also drift to other rooms, affecting the living environment of the entire family. In addition, fumes can also pose a potential threat to people's health.

[0059] After determining through gas flow that the exhaust duct of the range hood is blocked, the user can be reminded in time, for example, a message can be sent to the user through a mobile phone APP to remind the user to clean or replace the exhaust duct as soon as possible to avoid the fumes that cannot be discharged in time affecting the home environment and the user's health, thereby effectively improving the user experience.

[0060] Those skilled in the art should understand that, unless otherwise specified, the terms such as "inside" in the embodiments of the present invention used to indicate orientation or positional relationship are based on the actual use status of the pipeline 100. These terms are only used to facilitate the description and understanding of the technical solution of the present invention, and do not indicate or imply that the device or component referred to must have a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0061] Unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. A person skilled in the art should be able to understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0062] In the description of the present embodiment, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0063] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A device for detecting gas flow in a pipeline, comprising: An ultrasonic transmitter and an ultrasonic receiver are arranged on the inner wall of the pipeline in a relative manner, and a spoiler rod perpendicular to the flow direction of the gas is arranged between the ultrasonic transmitter and the ultrasonic receiver, the ultrasonic transmitter is configured to generate a first ultrasonic signal when a high and low level pulse signal of a preset frequency is applied, and the ultrasonic receiver is configured to receive a second ultrasonic signal and convert it into an amplitude modulated carrier electrical signal corresponding to the amplitude and frequency, wherein the second ultrasonic signal is affected by the gas that generates a Karman vortex street phenomenon when passing through the spoiler rod; A signal demodulation circuit, whose input end is connected to the ultrasonic receiver and is configured to process the input amplitude modulated carrier electrical signal to output a Karman vortex street pulse signal with a complete waveform; as well as The data processing module is connected to the output end of the signal demodulation circuit and is configured to obtain the pulse frequency of the Karman vortex pulse signal, the width of the spoiler rod and the cross-sectional area of ​​the pipeline to determine the flow rate of the gas.

2. The device according to claim 1, wherein the signal demodulation circuit comprises: A preprocessing circuit configured to preprocess the amplitude modulated carrier electrical signal; An envelope detector is configured to perform envelope detection on the pre-processed amplitude modulated carrier electrical signal to extract an envelope signal; as well as The voltage comparator is configured to output the input envelope signal as the Karman vortex pulse signal with a complete waveform.

3. The apparatus according to claim 2, wherein the pre-processing circuit comprises: A voltage follower, a second-order active low-pass filter, and a common-mode proportional amplifier are connected in sequence, and The ultrasonic receiver is connected to the voltage follower, and the in-phase proportional amplifier is connected to the envelope detector.

4. The device according to claim 3, wherein: The voltage follower is configured to perform impedance transformation on the input amplitude modulated carrier electrical signal to reduce distortion.

5. The device according to claim 4, wherein: The second-order active low-pass filter is configured to perform second-order active low-pass filtering on the amplitude modulated carrier electrical signal, wherein the cut-off frequency is set to the preset frequency.

6. The device according to claim 5, wherein: The in-phase proportional amplifier is configured to perform in-phase proportional amplification on the amplitude modulated carrier electrical signal, and The in-phase proportional amplifier includes a first amplifier and a second amplifier to perform two-stage amplification on the amplitude modulated carrier electrical signal.

7. The device according to claim 1, wherein: The data processing module is further configured to determine the flow rate of the gas according to the pulse frequency and the width, and determine the flow rate according to the flow rate and the cross-sectional area.

8. The device according to claim 7, wherein: The data processing module is also configured to: calculate the flow velocity using the formula V=f*b / Sr, where V is the flow velocity, f is the pulse frequency, b is the width, and Sr is the Strouhal number; calculate the flow rate using the formula Q=V*S, where Q is the flow rate and S is the cross-sectional area.

9. The device according to claim 1, wherein: The data processing module is further configured to count the rising edge or the falling edge of the Karman vortex pulse signal to obtain the pulse frequency.

10. The apparatus according to claim 1, further comprising: The pulse generating circuit is connected to the ultrasonic transmitter and is configured to generate the high and low level pulse signals.

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