Circuit structure of ultrasonic flowmeter

Abstract

The utility model discloses a circuit structure of an ultrasonic flowmeter, which comprises a digital logic circuit, a digital-analog mixed signal circuit and an analog signal circuit, the digital-analog mixed signal circuit is connected with the digital logic circuit and the analog signal circuit, the digital logic circuit is connected with an ultrasonic transmitting transducer, and the analog signal circuit is connected with an ultrasonic receiving transducer; power line cathodes of the digital logic circuit, the digital-analog mixed signal circuit and the analog signal circuit are gathered in the PCB and are connected to the same grounding node to form a star-shaped grounding structure; the grounding node is electrically connected with a ground wire. According to the utility model, power supplies and ground wires of different functional modules are subjected to single-point grounding, so that the noise of the digital logic circuit can be limited within a specific circuit range, and the quality of ultrasonic echo signals can be remarkably improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to ultrasonic measurement technical field, especially relate to a circuit structure of ultrasonic flowmeter. BACKGROUND

[0002] In the existing ultrasonic fluid measurement system, the excitation drive circuit is responsible for driving the transducer to send acoustic signals, and these acoustic waves propagate to the ultrasonic receiving transducer through the fluid. However, the attenuation of acoustic waves in the fluid is large, and the signal becomes weak, resulting in a small peak-to-peak value of the received ultrasonic echo signal induced voltage, which is easily affected by environmental noise, thereby reducing the signal-to-noise ratio. In order to solve this problem, an analog signal conditioning circuit needs to be added to the ultrasonic fluid measurement system.

[0003] Therefore, the fluid measurement circuit includes a digital logic circuit, an analog signal conditioning circuit, a clock signal generating circuit, and a power supply circuit. The pulsating signal generated by the state transformation of the digital logic circuit and the high-frequency oscillation signal of the clock signal generating circuit will cause current fluctuations in the circuit. The noise signal characterized by current fluctuations has a large amplitude and a wide frequency coverage compared to the ultrasonic echo signal.

[0004] The ultrasonic echo signal superimposed with the noise signal is amplified by the signal conditioning circuit and then converted to digital, which results in the collected digital signal containing a large amount of noise signal component. Although a differential filter amplifier and a band-pass filter are used in the signal conditioning and amplification circuit to suppress out-of-band noise and improve signal quality, the filter circuit cannot effectively attenuate the noise signal within the passband. Due to the random influence of the noise signal, the sound flight time difference measured and calculated by the signal processing unit fluctuates greatly, which cannot meet the engineering application requirements.

[0005] Therefore, how to provide a circuit structure of an ultrasonic flowmeter that reduces the noise impact within the passband is a technical problem that needs to be solved by those skilled in the art. Utility model content

[0006] The utility model provides a circuit structure of ultrasonic flowmeter according to the above research status, and the ultrasonic flowmeter wave echo signal quality is improved by optimizing PCB layout.

[0007] The utility model provides a circuit structure of ultrasonic flowmeter, which comprises a digital logic circuit, a digital-analog hybrid signal circuit and an analog signal circuit, wherein the digital-analog hybrid signal circuit is connected with the digital logic circuit and the analog signal circuit, the digital logic circuit is connected with an ultrasonic transmitting transducer, and the analog signal circuit is connected with an ultrasonic receiving transducer.

[0008] The negative poles of the power supply lines of the digital logic circuit, the digital-analog hybrid signal circuit and the analog signal circuit are gathered in the PCB circuit board and connected to the same ground node, forming a star-shaped ground structure; and the ground node is electrically connected with a ground wire.

[0009] Preferably, the digital logic circuit comprises an ultrasonic wave transmitting transducer excitation driving circuit, a logic operation circuit and a clock generation circuit; the logic operation circuit is electrically connected with the ultrasonic wave transmitting transducer excitation driving circuit and the clock generation circuit; the ultrasonic wave transmitting transducer excitation driving circuit is electrically connected with the ultrasonic wave transmitting transducer; and the logic operation circuit is electrically connected with the digital-analog hybrid signal circuit.

[0010] Preferably, the analog signal circuit comprises an analog signal conditioning circuit; and the analog signal conditioning circuit is electrically connected with the ultrasonic wave receiving transducer and the digital-analog hybrid signal circuit.

[0011] Preferably, the digital-analog hybrid signal circuit comprises an analog signal acquisition circuit; and the analog signal acquisition circuit is electrically connected with the digital logic circuit and the analog signal circuit.

[0012] Preferably, the positive connection end of the power supply of the digital logic circuit, the digital-analog hybrid signal circuit and the analog signal circuit is provided with a decoupling capacitor.

[0013] Preferably, the utility model also comprises a power supply circuit, and the ground wire of the power supply circuit is connected with the ground node.

[0014] Preferably, the logic operation circuit is also electrically connected with an external display control circuit.

[0015] Compared with the prior art, the utility model has the following beneficial effects:

[0016] The utility model limits the noise generated by the pulsation signal generated by the digital logic circuit in the ultrasonic flowmeter circuit, the space radiation signal received by the transducer and the power supply crosstalk signal in a specific range.

[0017] The utility model effectively divides and connects the power supply and reference ground of each circuit module, forms a current closed loop inside the circuit module, reduces the overflow of high-frequency noise and reduces the influence of digital noise in the circuit on the analog circuit.

[0018] The utility model adds a decoupling capacitor to the power supply inlet position of each circuit module to absorb rapidly changing current and reduce the propagation of high-frequency noise along the power supply line.

[0019] Through the above measures, the utility model can significantly improve the quality of the ultrasonic wave echo signal, ensure that the time-of-flight data obtained by the signal processor is more stable and accurate and meet the needs of engineering applications. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0021] Figure 1 is the composition structure diagram of the circuit structure of the ultrasonic flowmeter provided by the embodiment of the present application;

[0022] Figure 2 is the star grounding structure schematic diagram of the ultrasonic flowmeter provided by the embodiment of the present application.

[0023] In the figure,

[0024] 1 is an ultrasonic wave transmitting transducer, 2 is an ultrasonic wave transmitting transducer excitation driving circuit, 3 is an external display control circuit, 4 is a digital logic circuit, 5 is a clock generation circuit, 6 is an ultrasonic wave receiving transducer, 7 is an analog signal conditioning circuit, 8 is an analog signal acquisition circuit, 9 is a power supply circuit, and 10 is a grounding node. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] As shown in the figure, Figure 1 The circuit structure of the ultrasonic flowmeter disclosed by the present application includes a digital logic circuit, a digital-analog hybrid signal circuit and an analog signal circuit. The digital-analog hybrid signal circuit is connected with the digital logic circuit and the analog signal circuit. The digital logic circuit is connected with the ultrasonic wave transmitting transducer 1. The analog signal circuit is connected with the ultrasonic wave receiving transducer. As shown in the figure, Figure 2 The negative poles of the power supply lines of the digital logic circuit, the digital-analog hybrid signal circuit and the analog signal circuit are gathered in the PCB circuit board and connected to the same grounding node 10, forming a star grounding structure. The grounding node 10 is electrically connected with the ground wire.

[0027] The power supply and ground wire of different functional modules are single-point grounded in the embodiment, which can limit the noise of the digital logic circuit in a specific circuit range and can avoid forming a large loop area. If multiple modules share the same ground wire path, the current between them can form a larger loop, which can increase electromagnetic radiation and easily introduce common-mode noise. Single-point connection reduces the possibility of these large loops, limits the noise of the digital module in a specific circuit range, reduces the generation of common-mode current, further reduces the influence of digital noise on analog signals, greatly improves the signal-to-noise ratio of the ultrasonic echo signal after amplification by the analog signal conditioning circuit, and finally obtains a time of flight that meets the application requirements after data acquisition by the digital-analog hybrid circuit and logic operation by the digital logic circuit.

[0028] In one embodiment, the digital logic circuit operates the circuit by switching high and low signal levels to transmit information. At the moment of switching the signal level, high-frequency current flows through the signal line. The current not only flows in the signal line, but also flows in the power supply and reference ground. These high-frequency currents used in the digital logic circuit are considered as the cause of noise. The digital logic circuit includes an ultrasonic transmitting transducer excitation driving circuit 2, a logic operation circuit 4, and a clock generation circuit 5. The logic operation circuit 4 is electrically connected to the ultrasonic transmitting transducer excitation driving circuit 2 and the clock generation circuit 5. The ultrasonic transmitting transducer excitation driving circuit 2 is electrically connected to the ultrasonic transmitting transducer 1. The logic operation circuit 4 is electrically connected to the digital-analog hybrid signal circuit.

[0029] In one embodiment, the analog signal circuit includes an analog signal conditioning circuit 7. The analog signal conditioning circuit 7 is electrically connected to the ultrasonic receiving transducer and the digital-analog hybrid signal circuit.

[0030] In one embodiment, the digital-analog hybrid signal circuit includes an analog signal acquisition circuit 8. The analog signal acquisition circuit 8 is electrically connected to the digital logic circuit and the analog signal circuit.

[0031] In combination with the above embodiment, according to the functions and signal characteristics of the ultrasonic fluid measurement circuit, the noise generated by the pulsating signal of the digital logic circuit in the fluid measurement circuit, the spatial radiation signal received by the ultrasonic receiving transducer, and the power crosstalk signal are limited within a specific range. After the ultrasonic echo signal is electromechanically converted by the transducer and enters the signal conditioning circuit for amplification, a high signal-to-noise ratio echo signal with an amplitude meeting the conversion requirements can be obtained. The analog signal acquisition circuit samples, digitizes, and calculates the amplified echo signal, and finally obtains relatively stable ultrasonic time of flight data. The precision of the data can meet the engineering needs.

[0032] In one embodiment, in order to prevent the noise of the digital logic circuit from affecting the performance of the analog signal circuit and the digital-analog mixed circuit, a decoupling capacitor is additionally arranged at the positive connection terminal of the power supply of the digital logic circuit, the digital-analog mixed signal circuit and the analog signal circuit, which attenuates the influence of the noise on the analog signal conditioning circuit 7 and the analog signal acquisition circuit 8 to a certain extent.

[0033] In one embodiment, the power supply circuit 9 is further included, and the ground node 10 is connected with the ground wire of the power supply circuit 9. In this embodiment, the reference ground of the module circuits of the ultrasonic fluid metering circuit, including the ultrasonic transmitting transducer excitation driving circuit 2, the logic operation circuit 4, the clock generation circuit 5, the analog signal conditioning circuit 7 and the analog signal acquisition circuit 8, is independently led out, is collected at 10 through a star structure, and is finally connected with the ground wire of the power supply circuit 9.

[0034] In one embodiment, the logic operation circuit 4 is further electrically connected with the external display control circuit 3.

[0035] The circuit structure of the ultrasonic flow meter provided by the utility model is described in detail above, the principle and implementation mode of the utility model are described by applying specific examples in this paper, and the description of the above embodiments is only used to help understand the method and core idea of the utility model; meanwhile, for the general technical personnel in the field, the specific implementation mode and application range will be changed according to the idea of the utility model, and according to the above, the content of the specification should not be understood as the limitation of the utility model.

[0036] In this paper, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or sequence between the entities or operations. Moreover, the term "include", "contain" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitation, the element defined by the statement "including a" does not exclude the existence of other same elements in the process, method, article or equipment including the element.

Claims

1. A circuit structure of an ultrasonic flowmeter, characterized in that: include: A digital logic circuit, a digital-analog mixed signal circuit and an analog signal circuit, wherein the digital-analog mixed signal circuit is connected to the digital logic circuit and the analog signal circuit, the digital logic circuit is connected to an ultrasonic transmitting transducer, and the analog signal circuit is connected to an ultrasonic receiving transducer; wherein, The negative poles of the power lines of the digital logic circuit, the digital-analog mixed signal circuit and the analog signal circuit are collected in the PCB circuit board and connected to the same grounding node to form a star grounding structure; the grounding node is electrically connected to the ground wire.

2. The circuit structure of an ultrasonic flowmeter according to claim 1, characterized in that: The digital logic circuit includes: an ultrasonic transmitting transducer excitation drive circuit, a logic operation circuit and a clock generation circuit; wherein, the logic operation circuit is electrically connected to the ultrasonic transmitting transducer excitation drive circuit and the clock generation circuit, the ultrasonic transmitting transducer excitation drive circuit is electrically connected to the ultrasonic transmitting transducer, and the logic operation circuit is electrically connected to the digital-analog mixed signal circuit.

3. The circuit structure of an ultrasonic flowmeter according to claim 1, characterized in that: The analog signal circuit includes an analog signal conditioning circuit; the analog signal conditioning circuit is electrically connected to the ultrasonic receiving transducer and the digital-analog mixed signal circuit.

4. The circuit structure of an ultrasonic flowmeter according to claim 1, characterized in that: The digital-analog mixed signal circuit includes an analog signal acquisition circuit; the analog signal acquisition circuit is electrically connected to the digital logic circuit and the analog signal circuit.

5. The circuit structure of an ultrasonic flowmeter according to claim 1, characterized in that: The positive power supply terminals of the digital logic circuit, the digital-analog mixed signal circuit and the analog signal circuit are provided with decoupling capacitors.

6. The circuit structure of an ultrasonic flowmeter according to claim 1, characterized in that: A power supply circuit is also included, and the ground node is connected to a ground line of the power supply circuit.

7. The circuit structure of an ultrasonic flowmeter according to claim 2, characterized in that: The logic operation circuit is also electrically connected to an external display control circuit.

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