TWI879420B - Ultrasonic flowmeter and flow measurement method - Google Patents

Abstract

An ultrasonic flowmeter suitable for measuring transmission time of ultrasonic wave in fluid is provided, where the ultrasonic flowmeter is disposed on non-uniform pipes, which includes a first sensor, a second sensor, and a processing circuit. The processing circuit performs following steps: controlling the first sensor and the second sensor to respectively emit a first emitting ultrasonic signal and a second emitting ultrasonic signal within an emitting time-cycle; determining whether to increase respective transmission amounts of the first emitting ultrasonic signal and the second emitting ultrasonic signal according to a first signal stability of the first transmission ultrasonic signal and a second signal stability of the second transmitted ultrasonic signal; and calculating flow of fluid.

Description

Ultrasonic flow meter and flow detection method

This disclosure relates to the technical field of fluid flow detection, and in particular to an ultrasonic flow meter and a flow detection method.

Flowmeter is one of the important instruments in industrial measurement. It is closely related to various industrial applications and scientific research, and the requirements for measurement accuracy are getting higher and higher. Flowmeters are widely used in various fields, such as semiconductor manufacturing processes: coating equipment, etching equipment, cleaning equipment, and drying equipment manufacturing processes all use flowmeter measurement technology.

After developing applications in many industries, although ultrasonic flowmeters are relatively new measuring instruments, they are non-contact with the measuring body, so they do not produce resistance to the fluid, extend the life of the sensor, and avoid pollution. In recent years, they have attracted the attention and use of many industries.

An ultrasonic flow meter usually includes a transmitter that emits ultrasonic signals and a receiver that receives ultrasonic signals. The transmitter and the receiver are respectively arranged at two positions on the pipeline that transports the fluid to emit ultrasonic signals and receive ultrasonic signals respectively, and the flow rate of the fluid in the pipeline is detected by the time difference between emission and reception. However, when one of the transmitter and the receiver of the ultrasonic flow meter is arranged on the casing or bend of the pipeline (i.e., the thickness of the pipeline is too thick), the ultrasonic signal emitted by the transmitter may be affected (the additional time difference generated cannot be detected, or the signal is excessively attenuated) and cannot reach the receiver. Therefore, the existing ultrasonic flow meter is still not dynamically applicable to measure the flow rate of the fluid transported by the pipeline of any thickness.

The main purpose of this disclosure is to provide an ultrasonic flowmeter and flow detection method, which can prevent the situation that the ultrasonic signal cannot be found according to the standard set inner diameter and outer diameter values of the pipeline due to differences caused by sedimentation in the inner diameter of the pipeline, or different outer diameter thicknesses caused by sleeves or adapter pipes on the outer diameter (the time difference between the transmission time and the standard time cannot be detected, or the signal is excessively attenuated). .

In order to achieve the above-mentioned purpose, the ultrasonic flowmeter disclosed in the present invention is arranged in a non-uniform thickness pipeline, wherein the ultrasonic flowmeter comprises: an ultrasonic flowmeter, comprising: a first sensor and a second sensor, configured to transmit and receive a signal; and a processing circuit, coupled to the first sensor and the second sensor, configured to perform the following steps: (a) controlling the first sensor and the second sensor to transmit a first transmission ultrasonic signal and a second transmission ultrasonic signal respectively in a transmission time cycle; (b) controlling the second sensor to receive the first transmission ultrasonic signal, and controlling the first sensor to receive the second transmission ultrasonic signal; (c) detecting a first signal stability of the first transmission ultrasonic signal received by the second sensor and whether a second signal stability of the second transmitted ultrasonic signal received by the first sensor is greater than a stability threshold; (d) when the first signal stability or the second signal stability is not greater than the stability threshold, increasing the number of transmissions of the first transmitted ultrasonic signal and the second transmitted ultrasonic signal, and adjusting the indication of the first sensor and the second sensor, respectively; a position parameter of an installation position, and return to step (a); and (e) when the first signal stability and the second signal stability are greater than the stability threshold, the flow rate of the fluid is calculated according to the time of emitting the first ultrasonic signal, the time of receiving the first ultrasonic signal, the time of emitting the second ultrasonic signal, and the time of receiving the second ultrasonic signal.

In order to achieve the above-mentioned purpose, the flow detection method disclosed in the present invention is applied to an ultrasonic flow meter installed in a non-uniform thickness pipeline, wherein the ultrasonic flow meter includes a first sensor, a second sensor and a processing circuit, wherein the flow detection method includes: (a) using the processing circuit to control the first sensor and the second sensor to respectively transmit a first transmission ultrasonic signal and a second transmission ultrasonic signal in a transmission time cycle; (b) using the processing circuit to control the second sensor to receive the first transmission ultrasonic signal, and control the first sensor to receive the second transmission ultrasonic signal; (c) using the processing circuit to detect a first signal stability of the first transmission ultrasonic signal received by the second sensor and a second signal stability of the first transmission ultrasonic signal received by the first sensor (d) when the first signal stability or the second signal stability is not greater than the stability threshold, the processing circuit is used to increase the number of shots of the first ultrasonic signal and the second ultrasonic signal, and adjust an inner diameter parameter and an outer diameter parameter of the non-uniform thickness pipe. number, and then return to step (a); and (e) when the first signal stability and the second signal stability are greater than the stability threshold, the processing circuit is used to calculate the flow rate of the fluid according to the time of transmitting the first ultrasonic signal, the time of receiving the first ultrasonic signal, the time of transmitting the second ultrasonic signal, and the time of receiving the second ultrasonic signal.

Compared with the related technologies, the technical effect achieved by the present disclosure is to increase the number of ultrasonic signal emissions within a fixed emission cycle by judging whether the transmission stability of the ultrasonic signal is too low, so as to prevent the ultrasonic signal from being unable to be correctly transmitted due to the pipe wall and the pipe joint wall, thereby preventing the flow rate of the fluid in the pipe from being unable to be measured.

100: Ultrasonic flow meter

110(a): First sensor

110(b): Second sensor

120: Processing circuit

S1~S2: outer surface

us:First emission of ultrasonic signal

ds: Second ultrasonic signal transmission

PP: Pipeline

PF: Pipe fitting

FD: Flow direction

r1: inner diameter

r2~r3: outer diameter

RT: Transmit time cycle

WT: window time period

tt1~tt2, tt1’: Spending time

△t: time difference

△t’: Transmission time difference

S410~S470: Steps

t1~t2: time point

DAC1~DAC2: curve

LL: Lower limit

FIG. 1A is a schematic diagram of a longitudinal cross-section of an ultrasonic flow meter in some embodiments.

FIG. 1B is a block diagram of an ultrasonic flow meter in some embodiments.

FIG2A is a schematic diagram showing a method for setting up the first sensor and the second sensor in some embodiments.

FIG2B is a schematic diagram showing a method for setting up the first sensor and the second sensor in some embodiments.

Figure 3 shows a schematic diagram of the waveform of an ultrasonic signal under normal circumstances.

FIG4 is a flow chart showing a flow detection method in some embodiments.

FIG5 is a schematic diagram showing comparative waveforms of ultrasonic signals in some embodiments.

FIG6 is a detailed schematic diagram showing the waveform of the received first transmitted ultrasonic signal in some embodiments.

FIG7 is a schematic diagram showing the waveform of an ultrasonic signal in some other embodiments.

FIG8 is a detailed schematic diagram of the waveform of the received ultrasonic signal in some other embodiments.

FIG9 is a flow chart showing the steps further included in the flow detection method in some embodiments.

FIG10 is a schematic diagram showing a distance amplitude curve of a received ultrasonic signal in some embodiments.

FIG11 is a flow chart showing the steps included in one step of a flow detection method in some embodiments.

Referring to FIG. 1A and FIG. 1B, FIG. 1A is a schematic diagram of a longitudinal section of an ultrasonic flow meter 100 in some embodiments, and FIG. 1B is a block diagram of an ultrasonic flow meter 100 in some embodiments. As shown in FIG. 1A and FIG. 1B, the ultrasonic flow meter 100 disclosed herein includes a first transducer 110(a), a second transducer 110(b), and a processing circuit 120, wherein the processing circuit 120 is coupled to the first transducer 110(a) and the second transducer 110(b).

In some embodiments, the first sensor 110(a) and the second sensor 110(b) can be implemented by any ultrasonic sensing element or circuit. In some embodiments, the processing circuit 120 can be implemented by a central processing unit (CPU), a micro control unit (MCU), a programmable logic controller (PLC), a system on chip (SoC) or a field programmable gate array (FPGA), but is not limited thereto.

In some embodiments, the ultrasonic flow meter 100 may further include an input interface (not shown) and a memory (not shown). In some embodiments, the user may input the fluid type, the average outer diameter of the pipe PP and the pipe fitting PF, the inner diameter r1 of the pipe, the wall thickness of the pipe PP (i.e., r2-r1), the material of the pipe PP, and the installation method through the input interface. In some embodiments, the processing circuit 120 can read the sound velocity of the corresponding fluid type and the sound velocity of the material of the corresponding pipe PP from the memory according to the above-mentioned input data, and calculate the horizontal installation distance between the first sensor 110 (a) and the second sensor 110 (b), the emission time cycle (or called the pre-wave time cycle), and the ultrasonic transmission time according to the above-mentioned input data, the sound velocity of the corresponding fluid type and the sound velocity of the material of the corresponding pipe PP. Then, the processing circuit 120 can calculate the receiver window period according to the transmission time period and the ultrasound transmission time, and detect the time difference described later in the window period, wherein the window period is a time period during which the ultrasound signal can be received. It is worth noting that the above calculation methods are all commonly used calculation methods in this field, so they will not be further described.

In this embodiment, the first sensor 110 (a) and the second sensor 110 (b) are arranged in pairs on the same line of the outer surface S1 of the pipe PP of the flow pipeline and the outer surface S2 of the pipe joint PF (i.e., the V method commonly used in the art). However, the pair arrangement of the first sensor 110 (a) and the second sensor 110 (b) is not limited to that shown in FIG. 1A, that is, in other embodiments, the first sensor 110 (a) and the second sensor 110 (b) can be arranged in other ways (e.g., the Z method, N method or W method commonly used in the art). It is worth noting that, since the pipe joint PF is sleeved on the pipe PP (i.e., it can be regarded as a pipe of non-uniform thickness), the outer diameter r2 of the pipe PP where the first sensor 110(a) is installed and the outer diameter r3 of the pipe joint PF where the second sensor 110(b) is installed are different. At this time, the reasonable pipe outer diameter range will fall between the outer diameter r2 of the pipe PP where the first sensor 110(a) is installed and the outer diameter r3 of the pipe joint PF where the second sensor 110(b) is installed. For example, the average value between the outer diameter r2 and the outer diameter r3 can be taken as the above average outer diameter, and the calculation in the above paragraph is performed using this average outer diameter, but it is not limited to this setting method.

Although the pipe connector PF is a sleeve connector as an example here, in other embodiments, the ultrasonic flowmeter 100 can also be applied to the case where the pipe connector PF is a elbow connector.

The following is an actual example to illustrate the installation method of the first sensor 110 (a) and the second sensor 110 (b) and different types of pipe joints PF. Referring to FIG. 2A, FIG. 2A shows the installation method of the first sensor 110 (a) and the second sensor 110 (b) in some embodiments. As shown in FIG. 2A, the difference between FIG. 2A and FIG. 1A is that the pipe joint PF is a curved pipe joint, and the first sensor 110 (a) and the second sensor 110 (b) are both installed at the two ends of the bend on the outer surface S2 of the pipe joint PF. In addition, the difference between FIG. 2A and FIG. 1A is that the first sensor 110 (a) directly transmits the first transmitted ultrasonic signal us to the second sensor 110 (b), and the second sensor 110 (b) directly transmits the second transmitted ultrasonic signal ds to the first sensor 110 (a), wherein the first transmitted ultrasonic signal us and the second transmitted ultrasonic signal ds will not generate reflections in the pipe PP as shown in FIG. 1A (i.e., a transmission method similar to the Z method). In this embodiment, the processing circuit 120 can also use the same method as above to calculate the horizontal installation distance between the first sensor 110 (a) and the second sensor 110 (b), the transmission time cycle, the ultrasonic transmission time, and the window time cycle.

Referring to FIG. 2B , FIG. 2B shows a method for setting the first sensor 110 (a) and the second sensor 110 (b) in some embodiments. As shown in FIG. 2B , the difference between FIG. 2B and FIG. 1A is that the first sensor 110 (a) and the second sensor 110 (b) are respectively set at different positions on the outer surface S1 of the pipe PP and the outer surface S2 of the pipe joint PF using the Z method. In addition, the difference between FIG. 2B and FIG. 1A is that the first sensor 110 (a) directly transmits the first transmitted ultrasonic signal us to the second sensor 110 (b), and the second sensor 110 (b) directly transmits the second transmitted ultrasonic signal ds to the first sensor 110 (a), wherein the first transmitted ultrasonic signal us and the second transmitted ultrasonic signal ds will not generate reflections in the pipe PP as shown in FIG. 1A (i.e., in the Z-method transmission mode). In this embodiment, the processing circuit 120 can also use the same method as above to calculate the horizontal installation distance between the first sensor 110 (a) and the second sensor 110 (b), the transmission time cycle, the ultrasonic transmission time, and the window time cycle.

Furthermore, in general, the first sensor 110(a) is used to emit a first ultrasonic signal us and receive a second ultrasonic signal ds emitted by the second sensor 110(b), and the second sensor 110(b) is used to emit the second ultrasonic signal ds and receive the first ultrasonic signal us emitted by the first sensor 110(a). The first sensor 110(a) emits the first ultrasonic signal us obliquely relative to the flow direction FD of the fluid in the flow pipe (for example, the direction of flow from left to right), and the first ultrasonic signal us is received by the second sensor 110(b). At the same time, the second sensor 110(b) obliquely emits a second ultrasonic signal ds in the opposite flow direction of the fluid in the flow pipe (i.e., the direction opposite to the flow direction FD), and is received by the first sensor 110(a), so that the flow rate can be measured from the transmission time difference between the first ultrasonic signal us and the second ultrasonic signal ds in the fluid.

In detail, refer to FIG. 3 , which shows a waveform of the first transmitted ultrasonic signal us and a waveform of the second transmitted ultrasonic signal ds under normal circumstances. As shown in FIG. 1A and FIG. 3 , the first sensor 110 (a) and the second sensor 110 (b) simultaneously transmit signals of the same frequency (e.g., 3 MHz) in the transmission time period RT. The first transmitted ultrasonic signal us emitted by the first sensor 110 (a) propagates in the pipe PP, and after a period of time, the second sensor 110 (b) receives the first transmitted ultrasonic signal us emitted by the first sensor 110 (a). Similarly, the ultrasonic signal ds emitted by the second sensor 110(b) will also propagate in the pipe PP, and the first sensor 110(a) will also receive the second ultrasonic signal ds emitted by the second sensor 110(b) after a period of time. Since the flow velocity and flow direction FD of the liquid are in the same direction as the propagation direction of the first ultrasonic signal us emitted by the first sensor 110(a) (for example, both are toward the right side of the pipe PP), the time when the second sensor 110(b) receives the first ultrasonic signal us will be earlier than the time when the first sensor 110(a) receives the second ultrasonic signal ds. In contrast, the flow velocity and flow direction FD of the liquid are in the opposite direction to the propagation direction of the second ultrasonic signal ds emitted by the second sensor 110 (b), so the time when the first sensor 110 (a) receives the second ultrasonic signal ds will be later than the time when the second sensor 110 (b) receives the first ultrasonic signal us.

Based on this, the processing circuit 120 detects the time tt1 taken for the second sensor 110 (b) to receive the first transmitted ultrasonic signal us and the time tt2 taken for the first sensor 110 (a) to receive the second transmitted ultrasonic signal ds in the window time period WT, and calculates the time difference Δt between the time tt1 and the time tt2. Then, the processing circuit 120 uses the time difference method (time of flight, TOF) to calculate the flow rate and flow rate of the liquid in the pipe PP (i.e., the measurement value obtained by the ultrasonic flowmeter 100 using the frequency of 3MHz) based on the time difference Δt between the first sensor 110 (a) and the second sensor 110 (b) receiving the second transmitted ultrasonic signal ds and the first transmitted ultrasonic signal us, respectively. It is worth noting that the present disclosure does not limit the formula for calculating flow rate and flow rate designed based on the principle of time difference method.

However, since the second sensor 110(b) is disposed on the outer surface S2 of the pipe joint PF, and both the first transmitted ultrasonic signal us and the second transmitted ultrasonic signal ds need to pass through the pipe wall of the pipe PP and the pipe wall of the pipe joint PF, an excessively thick pipe wall may cause the second sensor 110(b) to fail to receive the first transmitted ultrasonic signal us emitted by the first sensor 110(a) or cause the first sensor 110(a) to fail to receive the second transmitted ultrasonic signal ds emitted by the second sensor 110(b), and may also cause the first transmitted ultrasonic signal us received by the second sensor 110(b) or the second transmitted ultrasonic signal ds received by the first sensor 110(a) to have poor signal stability (i.e., the signal-to-noise ratio (SNR) is too low). In addition, compared with the general setting method, the pipe joint PF is more likely to cause a transmission time difference (the subsequent paragraphs will further explain this transmission time difference). Therefore, the flow velocity and flow rate of the fluid cannot be calculated by the time difference method. Based on this, the present disclosure proposes a flow detection method to solve the problem that the second sensor 110 (b) and the first sensor 110 (a) may not be able to receive the first transmitted ultrasonic signal us and the second transmitted ultrasonic signal ds respectively or the signal stability is poor. In addition, the flow detection method disclosed in the present disclosure further eliminates the above-mentioned transmission time difference by adjusting the inner diameter parameters and the outer diameter parameters (that is, the appropriate inner diameter of the pipe PP and the average outer diameter of the pipe PP and the pipe joint PF can correct the transmission time difference). In some embodiments, the inner diameter parameter includes the inner diameter of the pipe PP, and the outer diameter parameter includes the average outer diameter of the pipe PP and the pipe joint PF. The detailed steps will be described in the subsequent paragraphs and will not be further elaborated here.

Referring to FIG. 4 , FIG. 4 is a flow chart of a flow detection method in some embodiments, and the flow detection method is applicable to the ultrasonic flow meter 100 shown in FIG. 1A to FIG. 1B . As shown in FIG. 4 , first, in step S410, the processing circuit 120 controls the first sensor 110 (a) and the second sensor 110 (b) to transmit the first transmission ultrasonic signal us and the second transmission ultrasonic signal ds in the transmission time period RT. In some embodiments, in the initial state, the processing circuit 120 may set the number of transmissions of the first transmission ultrasonic signal us and the second transmission ultrasonic signal ds to 1. In other words, in the initial state, the processing circuit 120 can control the first sensor 110 (a) to transmit a first transmitted ultrasonic signal us that propagates in the forward direction and a second transmitted ultrasonic signal ds that propagates in the reverse direction in the transmission time period RT. In other embodiments, in the initial state, the processing circuit 120 can also set the number of transmissions of the first transmitted ultrasonic signal us and the second transmitted ultrasonic signal ds to other positive integers, without any special restrictions.

In step S420, the processing circuit 120 controls the second sensor 110 (b) to receive the first transmitted ultrasonic signal us, and controls the first sensor 110 (a) to receive the second transmitted ultrasonic signal ds. In step S430, the processing circuit 120 detects whether the first signal stability of the first transmitted ultrasonic signal us received by the second sensor 110 (b) and the second signal stability of the second transmitted ultrasonic signal ds received by the first sensor 110 (a) are greater than the stability threshold. When the first signal stability of the received first transmitted ultrasonic signal us or the second signal stability of the received second transmitted ultrasonic signal ds is not greater than the stability threshold, the processing circuit 120 executes step S440. On the contrary, when the first signal stability of the received first transmission ultrasonic signal us and the second signal stability of the received second transmission ultrasonic signal ds are greater than the stability threshold, the processing circuit 120 executes step S450.

In some embodiments, the threshold of the signal-to-noise ratio may be pre-set and stored in the memory of the ultrasonic flowmeter 100. In some embodiments, the first signal stability of the first transmitted ultrasonic signal us is the signal-to-noise ratio of the waveform of the received first transmitted ultrasonic signal us, wherein the stability threshold is the threshold of the signal-to-noise ratio. In some embodiments, the processing circuit 120 may calculate the average value and the standard deviation of the noise from the received first transmitted ultrasonic signal us. Then, the processing circuit 120 may sample multiple peak values of the received first transmitted ultrasonic signal us, and calculate the signal-to-noise ratio of the waveform of the received first transmitted ultrasonic signal us based on the multiple peak values, the average value of the noise, and the standard deviation of the noise. Similarly, the second signal stability is also calculated from the second transmitted ultrasonic signal ds in a similar manner, which will not be further elaborated here.

It is worth noting that, since the frequency of the first transmitted ultrasonic signal us transmitted from the first sensor 110 (a) is known (e.g., 3 MHz), the processing circuit 120 can identify the noise from the waveform of the received first transmitted ultrasonic signal us according to the frequency of the received first transmitted ultrasonic signal us, and further calculate the average value and standard deviation of the noise, wherein this calculation method is also a calculation method known in the art, and therefore, it will not be further described here.

The comparison between the stability of the first signal and the stability threshold is described below with an actual example. Referring to FIG. 5 , FIG. 5 is a schematic diagram showing a comparison of the waveform of the first transmitted ultrasonic signal us in some embodiments. As shown in FIG. 5 , when there is a pipe joint PF, the first sensor 110 (a) transmits a first transmitted ultrasonic signal us of a specific frequency in the transmission time period RT, and the second sensor 110 (b) receives the first transmitted ultrasonic signal us transmitted by the first sensor 110 (a) in the window time period WT.

It is worth noting that there is a time tt1' between the time of transmitting the first transmitted ultrasonic signal us and the time of receiving the first transmitted ultrasonic signal us. Compared with the example of FIG. 3 without the pipe joint PF, there is a transmission time difference △t' between the time tt1' and the time tt1. This transmission time difference △t' is caused by the uneven thickness of the pipe wall. In the subsequent step S440, the processing circuit 120 can adjust the inner diameter parameter and the outer diameter parameter to allow the user to adjust the inner diameter of the pipe PP and the average outer diameter of the pipe PP and the pipe joint PF (for example, select a thinner inner diameter of the pipe PP or a thinner average outer diameter of the pipe PP and the pipe joint PF to eliminate the transmission time difference △t'), and then change the inner diameter of the pipe PP and the average outer diameter of the pipe PP and the pipe joint PF according to the inner diameter parameter and the outer diameter parameter.

Next, the processing circuit 120 detects the signal-to-noise ratio of the first transmitted ultrasonic signal us received by the second sensor 110 (b). Further, referring to FIG. 6, FIG. 6 shows a detailed schematic diagram of the waveform of the received first transmitted ultrasonic signal us in some embodiments. As shown in FIG. 6, the processing circuit 120 identifies the signal received before time point t1 and after time point t2 as noise from the first transmitted ultrasonic signal us according to a specific frequency, and calculates the average value and standard deviation according to the peak value of the noise. Next, the processing circuit 120 calculates that the signal-to-noise ratio of the first transmitted ultrasonic signal us is not greater than the stability threshold according to the average value of the noise, the standard deviation of the noise, and the peak value of the signal between time points t1 and t2.

Returning to FIG. 4 , in step S440 , the processing circuit 120 increases the number of times the first ultrasonic signal us and the second ultrasonic signal ds are emitted, and adjusts the inner diameter parameter and the outer diameter parameter of the non-uniform thickness pipe (ie, as described in the above paragraph), and then returns to step S410 . In other words, once the processing circuit 120 finds that the stability of the first signal or the stability of the second signal is not greater than the stability threshold, the processing circuit 120 will control the first sensor 110 (a) and the second sensor 110 (b) to transmit the first transmission ultrasonic signal us one more time in the next transmission time cycle RT in step S410, and simultaneously increase the number of times the second sensor 110 (b) transmits the second transmission ultrasonic signal ds in the next transmission time cycle RT. At this time, the processing circuit 120 will further adjust the inner diameter parameter and the outer diameter parameter of the non-uniform thickness pipe (i.e., slightly reduce the parameter value (for example, reduce it by 10%)), and then continue to execute steps S420~S430 to continue to determine whether the first signal stability of all first transmitted ultrasonic signals us received by the second sensor 110(b) and the second signal stability of all second transmitted ultrasonic signals ds received by the first sensor 110(a) are greater than the stability threshold. At the same time, the inner diameter of the pipe PP and the average outer diameter of the pipe PP and the pipe joint PF are adjusted according to the inner diameter parameter and the outer diameter parameter (i.e., the values of the inner diameter and the average outer diameter are adjusted to the values of the inner diameter parameter and the outer diameter parameter) to eliminate the time difference caused by the uneven pipe wall thickness and increase the first signal stability and the second signal stability. It can be seen that when the processing circuit 120 detects that the first signal stability or the second signal stability is not greater than the stability threshold, the processing circuit 120 will simultaneously increase the number of shots of the first transmitted ultrasonic signal us and the second transmitted ultrasonic signal ds and adjust the inner diameter parameter and the outer diameter parameter of the non-uniform thickness pipe. In the present disclosure, the processing circuit 120 will continue to execute step S410 to step S440 until the first signal stability and the second signal stability are greater than the stability threshold, and then the processing circuit 120 will execute step S450.

The following is an actual example to illustrate the comparison between the stability of the first signal and the stability threshold after the processing circuit 120 increases the number of transmissions of the first transmitted ultrasonic signal us (taking one increase as an example). Referring to FIG. 7 , FIG. 7 is a schematic diagram showing the waveform of the first transmitted ultrasonic signal us in other embodiments. As shown in FIG. 7 , the first sensor 110 (a) transmits two first transmitted ultrasonic signals us of a specific frequency in the transmission time period RT (at this time, the first sensor 110 (a) also transmits two second transmitted ultrasonic signals ds of a specific frequency in the transmission time period RT), and the second sensor 110 (b) receives the first transmitted ultrasonic signal us transmitted by the first sensor 110 (a) in the window time period WT. Next, the processing circuit 120 detects the signal-to-noise ratio of the first transmitted ultrasonic signal us received by the second sensor 110 (b). Further, referring to FIG. 8 , FIG. 8 shows a detailed schematic diagram of the waveform of the received first transmitted ultrasonic signal us in other embodiments. As shown in FIG. 8 , the processing circuit 120 identifies the signal received before time point t1 and after time point t2 as noise from the first transmitted ultrasonic signal us according to a specific frequency, and calculates the average value and the standard deviation according to the peak value of the noise. Next, the processing circuit 120 calculates that the signal-to-noise ratio of the first transmitted ultrasonic signal us is greater than the stability threshold according to the average value of the noise, the standard deviation of the noise, and the peak value of the signal between time points t1 and t2. At this time, the processing circuit 120 starts to execute the above step S450. It is worth noting that the signal-to-noise ratio of the second transmitted ultrasonic signal ds is also calculated from the second transmitted ultrasonic signal ds in a similar manner. The signal-to-noise ratio of the second transmitted ultrasonic signal ds is also compared with the stability threshold in a similar manner. Therefore, it will not be further elaborated here.

Based on the above, the processing circuit 120 can identify whether the peak value of the received first transmitted ultrasonic signal us is too low (i.e., the pipe wall of the pipe PP and the pipe wall of the pipe joint PF block most of the energy of the first transmitted ultrasonic signal us) or whether the peak value of the received second transmitted ultrasonic signal ds is too low (i.e., the pipe wall of the pipe PP and the pipe wall of the pipe joint PF block most of the energy of the second transmitted ultrasonic signal ds) by judging whether the first signal stability and the second signal stability are greater than the stability threshold, and further judge whether to increase the number of times the first transmitted ultrasonic signal us and the second transmitted ultrasonic signal ds are emitted (i.e., further increase the emission energy of the first transmitted ultrasonic signal us and the emission energy of the second transmitted ultrasonic signal ds).

In some embodiments, the processing circuit 120 can determine whether the number of emissions of the first emission ultrasonic signal us after the increase is greater than the number threshold. When the number of emissions of the first emission ultrasonic signal us after the increase is not greater than the preset number threshold, the processing circuit 120 can continue to execute step S410. On the contrary, when the number of emissions of the first emission ultrasonic signal us after the increase is greater than the number threshold, the processing circuit 120 can generate a warning message. In some embodiments, the warning message indicates that the type of the first sensor 110 (a) and the second sensor 110 (b) currently set, or the setting method or setting position of the first sensor 110 (a) and the second sensor 110 (b), cannot detect the first transmission time of ultrasound in the fluid. It is worth noting that the flow detection method disclosed herein will also determine whether to generate a warning message in a similar manner based on the number of times the second ultrasonic signal ds is emitted after the increase.

Based on the above, the processing circuit 120 can avoid excessive energy consumption of the ultrasonic flowmeter 100 due to too many transmission times by judging whether the increased transmission times of the first transmission ultrasonic signal us or the increased transmission times of the second transmission ultrasonic signal ds is greater than the frequency threshold. In one embodiment, the frequency threshold is related to the type of the ultrasonic flowmeter 100, but is not limited thereto.

Returning to FIG. 4 , in step S450 , the processing circuit 120 calculates the flow rate of the fluid (i.e., the flow rate of the fluid in the pipe PP) according to the time of emitting the first emission ultrasonic signal us, the time of receiving the first emission ultrasonic signal us, the time of emitting the second emission ultrasonic signal ds, and the time of receiving the second emission ultrasonic signal ds.

Referring to FIG. 9 , FIG. 9 is a flow chart showing steps S460 to S470 further included in the flow detection method in some embodiments. As shown in FIG. 9 , first, when the stability of the first signal is greater than the stability threshold, the processing circuit 120 may further execute step S460. In step S460, the processing circuit 120 detects the value of the distance amplitude curve (DAC) of the first transmitted ultrasonic signal us received by the second sensor 110 (b). In step S470, the processing circuit 120 adjusts the number of transmissions of the first transmitted ultrasonic signal us according to the value of the distance amplitude curve of the first transmitted ultrasonic signal us, the lower limit value, and the number of transmissions of the first transmitted ultrasonic signal us, and returns to step S410.

In some embodiments, the processing circuit 120 may detect whether the values of the distance amplitude curve of the first transmitted ultrasonic signal us received by the second sensor 110 (b) are all greater than a preset lower limit. When at least one of the values of the distance amplitude curve of the received first transmitted ultrasonic signal us is not greater than the lower limit, the processing circuit 120 may continue to execute step S410. When the values of the distance amplitude curve of the received first transmitted ultrasonic signal us are all greater than the lower limit, the processing circuit 120 may determine whether the number of transmissions of the first transmitted ultrasonic signal us is greater than one. In some embodiments, when it is determined that the number of transmissions of the first transmitted ultrasonic signal us is not greater than one, the processing circuit 120 may continue to execute step S410. When it is determined that the number of transmissions of the first transmitted ultrasonic signal us is greater than one, the processing circuit 120 can reduce the number of transmissions of the first transmitted ultrasonic signal us (for example, by one), and continue to execute step S410 according to the reduced number of transmissions of the first transmitted ultrasonic signal us. It is worth noting that the flow detection method disclosed herein will also adjust the number of transmissions of the second transmitted ultrasonic signal ds according to the distance amplitude curve of the second transmitted ultrasonic signal ds in a similar manner, so it will not be further described here.

Based on the above, the processing circuit 120 can avoid the problem of excessive amplitude distance curve value due to excessive number of transmissions by judging whether the value of the amplitude distance curve is greater than the lower limit value, thereby reducing the energy consumption of the ultrasonic flow meter 100.

The following is an actual example to illustrate the comparison between the numerical value of the distance amplitude curve and the lower limit value. Referring to FIG. 10 , FIG. 10 is a schematic diagram of the distance amplitude curve of the first transmitted ultrasonic signal us in some embodiments. As shown in FIG. 10 , assuming that the distance amplitude curve of the first transmitted ultrasonic signal us received by the second sensor 110 (b) is the curve DAC1, when the processing circuit 120 determines that the numerical values on the curve DAC1 are all greater than the lower limit value LL, it will further determine whether the number of transmissions of the first transmitted ultrasonic signal us of the first sensor 110 (a) is greater than one. Assuming that the distance amplitude curve of the first transmitted ultrasonic signal us received by the second sensor 110 (b) is curve DAC2, the processing circuit 120 will determine that the values on the curve DAC2 are not all greater than the lower limit value LL, and directly continue to execute the above step S410.

Referring to FIG. 11 , FIG. 11 is a flow chart showing steps S451 to S453 further included in one step S450 of the flow detection method in some embodiments. The steps included in one step S450 of the flow detection method are also applicable to the ultrasonic flow meter 100 shown in FIG. 1A to FIG. 1B . As shown in FIG. 11 , first, in step S451 , the processing circuit 120 measures the first transmission time (i.e., the forward transmission time) of the ultrasonic wave in the fluid according to the time of transmitting the first transmission ultrasonic signal us and the time of receiving the first transmission ultrasonic signal us.

In step S452, the processing circuit 120 measures the second transmission time (i.e., reverse transmission time) of the ultrasound in the fluid according to the time of emitting the second ultrasound signal ds and the time of receiving the second ultrasound signal ds. In step S453, the processing circuit 120 calculates the flow rate of the fluid according to the first transmission time and the second transmission time. In some embodiments, the processing circuit 120 can calculate the time difference between the first transmission time and the second transmission time, and then calculate the flow rate and flow rate of the fluid according to the time difference using the above-mentioned time difference method.

For example, in the example of FIG. 3, as shown in FIG. 3, the processing circuit 120 calculates the difference between the time when the first sensor 110 (a) emits the first peak value of the first transmitted ultrasonic signal us and the time when the second sensor 110 (b) receives the first peak value of the first transmitted ultrasonic signal us (i.e., the time taken tt1). Then, the processing circuit 120 calculates the difference between the time when the second sensor 110 (b) emits the first peak value of the second transmitted ultrasonic signal ds and the time when the first sensor 110 (a) receives the first peak value of the second transmitted ultrasonic signal ds (i.e., the time taken tt2). Then, the processing circuit 120 calculates the flow rate of the fluid according to the time difference between the time taken tt1 and the time taken tt2.

In summary, the ultrasonic flowmeter and flow detection method proposed in the present disclosure determine whether to increase the number of transmissions of the ultrasonic signal within a fixed transmission time period according to the stability of the received transmission ultrasonic signal, so as to measure the time taken for the transmission ultrasonic signal to propagate forward and backward in the fluid. In this way, it is possible to prevent the flow of the fluid from being effectively measured due to the pipe wall and the pipe wall of the pipe joint blocking most of the energy of the transmission ultrasonic signal. In addition, the ultrasonic flowmeter and flow detection method proposed in the present disclosure further determine whether the number of transmissions of the ultrasonic signal is greater than the number threshold, so as to avoid excessive energy consumption due to too many transmissions. On the other hand, the ultrasonic flow meter and flow detection method proposed in this disclosure also determine whether the value of the amplitude-distance curve is greater than the lower limit value to avoid the problem of the amplitude-distance curve value being too large due to too many transmission times.

The above is only a preferred specific example of this disclosure, and does not limit the patent scope of this disclosure. Therefore, all equivalent changes made by applying the content of this disclosure are also included in the scope of this disclosure and are hereby stated.

100: Ultrasonic flow meter

110(a): First sensor

110(b): Second sensor

120: Processing circuit

Claims (10)

An ultrasonic flowmeter is disposed in a non-uniform thickness pipeline, wherein the ultrasonic flowmeter comprises: A first sensor and a second sensor, configured to transmit and receive a signal; and A processing circuit, coupled to the first sensor and the second sensor, configured to perform the following steps: (a) controlling the first sensor and the second sensor to transmit a first transmission ultrasonic signal and a second transmission ultrasonic signal respectively in a transmission time cycle; (b) controlling the second sensor to receive the first transmission ultrasonic signal, and controlling the first sensor to receive the second transmission ultrasonic signal; (c) Detecting whether a first signal stability of the first transmitted ultrasonic signal received by the second sensor and a second signal stability of the second transmitted ultrasonic signal received by the first sensor are greater than a stability threshold; (d) When the first signal stability or the second signal stability is not greater than the stability threshold, increasing the number of times of each of the first transmitted ultrasonic signal and the second transmitted ultrasonic signal, and adjusting an inner diameter parameter and an outer diameter parameter of the non-uniform thickness pipe, and then returning to step (a); and (e) When the first signal stability and the second signal stability are greater than the stability threshold, the flow rate of the fluid is calculated according to the time of emitting the first ultrasonic signal, the time of receiving the first ultrasonic signal, the time of emitting the second ultrasonic signal, and the time of receiving the second ultrasonic signal. An ultrasonic flow meter as described in claim 1, wherein the first signal stability of the first transmitted ultrasonic signal is a signal-to-noise ratio of a waveform of the first transmitted ultrasonic signal received by the second sensor, and wherein the stability threshold is a threshold of the signal-to-noise ratio. The ultrasonic flowmeter as described in claim 1, wherein step (d) includes: Determining whether the number of shots after the increase of the first ultrasonic signal is greater than a threshold value; When the number of shots after the increase of the first ultrasonic signal is not greater than a threshold value, continuing to execute step (a) according to the number of shots after the increase of the first ultrasonic signal; and When the number of shots after the increase of the first ultrasonic signal is greater than the threshold value, generating a warning message. The ultrasonic flow meter as described in claim 1, wherein the processing circuit is further configured to perform the following steps: When the stability of the first signal is greater than the stability threshold, detecting the value of a distance amplitude curve of the first transmitted ultrasonic signal received by the second sensor; and According to the value of the distance amplitude curve of the first transmitted ultrasonic signal, a lower limit value and the number of transmissions of the first transmitted ultrasonic signal, adjusting the number of transmissions of the first transmitted ultrasonic signal. The ultrasonic flowmeter as described in claim 1, wherein step (e) comprises: Measuring a first transmission time of an ultrasound wave in the fluid according to the time of transmitting the first transmission ultrasonic signal and the time of receiving the first transmission ultrasonic signal; Measuring a second transmission time of the ultrasound wave in the fluid according to the time of transmitting the second transmission ultrasonic signal and the time of receiving the second transmission ultrasonic signal; and Calculating the flow rate of the fluid according to the first transmission time and the second transmission time. A flow detection method is applied to an ultrasonic flow meter installed in a non-uniform thickness pipeline, wherein the ultrasonic flow meter includes a first sensor, a second sensor and a processing circuit, wherein the flow detection method includes: (a) using the processing circuit to control the first sensor and the second sensor to respectively transmit a first transmission ultrasonic signal and a second transmission ultrasonic signal in a transmission time cycle; (b) using the processing circuit to control the second sensor to receive the first transmission ultrasonic signal, and control the first sensor to receive the second transmission ultrasonic signal; (c) using the processing circuit to detect whether a first signal stability of the first transmission ultrasonic signal received by the second sensor and a second signal stability of the second transmission ultrasonic signal received by the first sensor are greater than a stability threshold; (d) When the first signal stability or the second signal stability is not greater than the stability threshold, the processing circuit is used to increase the number of shots of the first ultrasonic signal and the second ultrasonic signal, and adjust an inner diameter parameter and an outer diameter parameter of the non-uniform thickness pipe, and then return to step (a); and (e) When the first signal stability and the second signal stability are greater than the stability threshold, the processing circuit is used to calculate the flow rate of the fluid according to the time of emitting the first ultrasonic signal, the time of receiving the first ultrasonic signal, the time of emitting the second ultrasonic signal, and the time of receiving the second ultrasonic signal. A flow detection method as described in claim 6, wherein the first signal stability of the first transmitted ultrasonic signal is a signal-to-noise ratio of a waveform of the first transmitted ultrasonic signal received by the second sensor, wherein the stability threshold is a threshold of the signal-to-noise ratio. The flow detection method as described in claim 6, wherein step (d) includes: Using the processing circuit to determine whether the number of shots after the increase of the first ultrasonic signal is greater than a threshold value; When the number of shots after the increase of the first ultrasonic signal is not greater than a threshold value, using the processing circuit to continue to execute step (a) according to the number of shots after the increase of the first ultrasonic signal; and When the number of shots after the increase of the first ultrasonic signal is greater than the threshold value, using the processing circuit to generate a warning message. The flow detection method as described in claim 6 further includes: When the stability of the first signal is greater than the stability threshold, the processing circuit is used to detect the value of a distance amplitude curve of the first transmitted ultrasonic signal received by the second sensor; and The processing circuit is used to adjust the number of emissions of the first transmitted ultrasonic signal according to the value of the distance amplitude curve of the first transmitted ultrasonic signal, a lower limit value and the number of emissions of the first transmitted ultrasonic signal. The flow detection method as described in claim 6, wherein step (e) includes: Using the processing circuit to measure a first transmission time of an ultrasound wave in the fluid according to the time of transmitting the first transmission ultrasound signal and the time of receiving the first transmission ultrasound signal; and Using the processing circuit to measure a second transmission time of the ultrasound wave in the fluid according to the time of transmitting the second transmission ultrasound signal and the time of receiving the second transmission ultrasound signal; and Using the processing circuit to calculate the flow rate of the fluid according to the first transmission time and the second transmission time.

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