Flow control method and device

Abstract

The invention relates to the field of fluid flow control, in particular to a flow control method and device. The flow control method comprises the steps that the linear relation between the valve opening degree and the instantaneous cross section area is set, a plurality of continuous instantaneous flow intervals are preset, the corresponding valve opening degree and flow velocity intervals are obtained to make a comparison table, the proper initial adjustment opening degree is selected, and the flow to be adjusted and the residual valve opening degree are calculated and adjusted in a stepping mode; the invention further discloses a flow control device adopting the method. The flow control device comprises an ultrasonic measuring pipe section, a valve control assembly, a PCB control panel and a power source. The flow nonlinear problem is solved by adjusting the valve structure, linear control is achieved, the valve angle control precision is improved by adopting a high-resolution executing mechanism, efficient measurement and adjustment processing logic is achieved, instantaneous flow can be rapidly adjusted, and the flow velocity adjustment space of 0.01 L / h is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluid flow rate control, in particular to a flow control method and device. BACKGROUND

[0002] At present, in industrial production and scientific research, the importance of high-precision flow rate control is increasingly prominent, especially in the high-precision flow control of chemical industry, medicine, food industry and other industries, the liquid or gas flow rate regulation in precision instruments, and the fluid delivery system in laboratory research. Precise measurement and control of fluid flow rate are of great significance to ensure product quality, improve production efficiency, and promote scientific research progress. The development of high-precision flow rate control technology has significantly improved the product quality and production efficiency of related industries, providing strong support for the development of various fields.

[0003] In the existing flow rate control technology, V-shaped structure ball valves are generally used to control the flow. This control method mainly adjusts the angle of the valve to change the flow size, thereby achieving control of the flow rate. It can meet the needs of some scenes that do not require high precision control of flow rate to a certain extent. In many factory fluid delivery systems or some ordinary fluid control processes in experiments, V-shaped ball valves have become a common flow rate control method due to their simple structure and low cost.

[0004] However, the existing V-shaped ball valve flow rate control method has obvious defects. Since the V-shaped valve has a nonlinear characteristic in controlling fluid, it is difficult to adjust. Moreover, the adjustment resolution of the valve actuator is low and the response time is long, resulting in large flow rate fluctuations, greater than ±10%, which makes it difficult to achieve rapid response and high-precision control of fluid flow, and cannot meet the needs of high-precision control. SUMMARY

[0005] The present application solves the problem that V-shaped valves cannot meet the needs of high-precision control, and proposes a flow control method and device, which realizes a linear relationship between instantaneous flow and opening phase, and has efficient measurement and adjustment processing logic.

[0006] To achieve the above purpose, the following technical scheme is proposed: A flow control method, comprising the following steps: S1, setting a linear relationship between valve opening and instantaneous cross-sectional area; S2, under a set fluid pressure, a plurality of continuous instantaneous flow intervals are preset, the valve opening corresponding to the maximum instantaneous flow value and the minimum instantaneous flow value of each instantaneous flow interval is tested and obtained, the minimum flow rate and the maximum flow rate of each instantaneous flow interval are obtained according to the linear relationship between the valve opening and the instantaneous cross-sectional area, and a instantaneous flow interval-valve opening-flow rate interval table is obtained. S3, selecting the valve opening degree corresponding to the minimum value of the instantaneous flow rate in the previous interval of the interval in which the expected flow rate is located as the initial adjustment opening degree, fully opening the valve to the initial adjustment opening degree, and then stopping the valve adjustment; S4, subtracting the current flow rate from the expected flow rate to obtain a to-be-adjusted flow rate, and calculating the remaining opening degree of the valve according to the to-be-adjusted flow rate; S5, performing step-by-step adjustment according to 5%-10% of the remaining opening degree of the valve until the current flow rate is greater than or equal to the expected flow rate, and stopping the valve adjustment.

[0007] The application has efficient measurement and adjustment processing logic. Under rated fluid pressure, a plurality of opening degrees are preset for a plurality of different instantaneous flow rates. The plurality of different instantaneous flow rates and opening degrees are tabulated in the microcontroller according to the instantaneous flow rates from small to large, and the instantaneous flow rate and the opening degree are in a substantially linear relationship in the plurality of preset opening degrees.

[0008] Preferably, the S1 specifically comprises the following steps: setting the cross section of the flow hole of the ball valve as a rectangle, the long side of the rectangle being perpendicular to the rotation axis of the ball valve mechanism, and the S1 specifically comprises the following steps: setting the cross section of the flow hole of the ball valve as a rectangle, the long side of the rectangle being perpendicular to the rotation axis of the ball valve mechanism, and the instantaneous cross section area wherein I s is the current valve opening degree, I max is the maximum valve opening degree, a is the length of the long side of the rectangle, and b is the length of the short side of the rectangle.

[0009] Preferably, the S3 further comprises the following steps: determining whether the current flow rate is greater than the expected flow rate, if yes, fully closing the valve and performing the S3, and if no, performing the S3.

[0010] The current flow rate V s = Q s / A s , wherein Q s is the current flow rate measured and obtained, Q s is the instantaneous cross section area under the current valve opening degree I s , and the expected flow rate is a set input value.

[0011] Preferably, in the S3, when the interval of the expected flow rate is the first interval, the initial adjustment opening degree is equal to 0.

[0012] Preferably, the continuous instantaneous flow rate intervals in the S3 comprise [0, Q1), [Q1, Q2),..., [Q n-1 , Q n ), [Q n , Q max ], wherein Q maxQmax is the maximum flow corresponding to the maximum opening i (i = 1, 2,..., n) is the instantaneous flow node of the divided interval.

[0013] Preferably, the instantaneous flow nodes are set at equal intervals or at specific intervals according to specific working conditions.

[0014] A flow control device using the above-mentioned flow control method, comprising: An ultrasonic measurement pipe section, which is provided with a temperature acquisition sensor for acquiring fluid temperature and an ultrasonic measurement assembly for acquiring instantaneous flow of the fluid; A valve control assembly, which comprises a ball valve arranged in a water outlet pipe section connected with the outlet of the ultrasonic measurement pipe section, a valve stem for controlling rotation of the ball valve, and a drive motor for driving rotation of the valve stem, the valve stem being connected with the drive motor through the water outlet pipe section, and the valve stem being provided with a sealing ring; the cross section of the flow discharge hole of the ball valve is rectangular, and the long side of the rectangle is perpendicular to the rotation axis of the valve stem; A PCB control board, which is provided with a motor drive circuit electrically connected with the drive motor, a temperature acquisition circuit electrically connected with the temperature acquisition sensor, and an ultrasonic measurement circuit electrically connected with the ultrasonic measurement assembly; A power supply for supplying power to the whole device; The drive motor, the PCB control board, and the power supply are arranged in a casing fixed above the water outlet pipe section and the ultrasonic measurement pipe section.

[0015] The ultrasonic measurement assembly comprises an ultrasonic transducer arranged on the inner wall of the fluid pipe and a reflection bracket fixed inside the fluid pipe to form a reflection path, and the temperature sensor is used for detecting fluid temperature and compensating measurement error of the ultrasonic transducer. Unlike traditional mechanical flow meters, the ultrasonic flow meter can measure instantaneous flow in real time, has no time lag, and can realize rapid adjustment of instantaneous flow. The cross section of the flow discharge hole of the ball valve is rectangular, and the long side of the rectangle is perpendicular to the rotation axis of the valve stem. The valve structure is adjusted to solve the problem of flow nonlinearity, the shape of the flow discharge hole of the ball valve is adjusted, the size of the flow discharge hole of the valve is equal to the opening or closing when different openings are executed, and linear control is realized.

[0016] Preferably, the drive motor is a high-resolution Hall code motor, and the output end of the Hall code motor is provided with an encoder to provide a position feedback signal, and the encoder outputs positioning information through AB phase signals.

[0017] The application adopts high-resolution actuators to improve the precision of valve angle control, and the AB phase Hall encoder motor needs about 10s to open or close once when the motor actuator runs at full speed, and can generate 12000 ab phase signals. The precise phase signal plays a decisive role in the precise positioning of the on-off valve. And the precise valve positioning ultimately makes the application have a flow rate adjustment space of 0.01L / h.

[0018] As preferred, the PCB control board is provided with a position feedback module electrically connected with the encoder, for returning the actual opening degree information of the leakage hole to the controller to correct the linear relationship data table.

[0019] As preferred, the motor driving circuit comprises a PWM signal generator and a current feedback unit, and the PWM signal generator adjusts the rotating speed of the driving motor according to the pulse width modulation signal output by the controller.

[0020] The application has the following advantages: 1. Adjusting the flow measurement pipe section provides structural support for accurate ultrasonic water flow measurement. Unlike traditional mechanical flow meters, ultrasonic flow meters can measure instantaneous flow in real time, have no time lag, and can quickly adjust the instantaneous flow. 2. The valve structure solves the problem of flow nonlinearity. By adjusting the shape of the ball valve leakage hole, the size of the valve leakage hole is opened or closed in proportion to the opening degree, thereby realizing linear control. 3. High-resolution actuators are used to improve the precision of valve angle control. The AB phase Hall encoder motor needs about 10s to open or close once when the motor actuator runs at full speed, and can generate 12000 ab phase signals. This precise phase signal plays a decisive role in the precise positioning of the on-off valve. And the precise valve positioning ultimately has a flow rate adjustment space of 0.01L / h. 4. Efficient measurement and adjustment processing logic. Under the rated fluid pressure, a number of different instantaneous flow valves are pre-set to a number of opening degrees, and within the number of pre-set opening degrees, the instantaneous flow and the opening degree phase are basically linearly related. The number of different instantaneous flows and opening degrees are arranged in a table according to the instantaneous flow from small to large and pre-prepared in the microcontroller. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The method flowchart of the application.

[0022] Figure 2 The device structure diagram of the application.

[0023] Wherein: 1, ultrasonic measuring pipe section; 2, ball valve; 3, drive valve stem; 4, drive motor; 5, sealing ring; 6, PCB control board; 7, power supply; 8, temperature acquisition sensor. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be further described in detail below with reference to the drawings. The described embodiments are only possible technical implementations of the present application, but are not limited thereto, and other embodiments obtained by those skilled in the art without creative efforts based on the embodiments of the present application are also within the protection scope of the present application.

[0025] The present application mainly adopts setting flow control relationship and parameters and step-by-step adjusting valve opening degree, so as to achieve accurate linear control of flow, improve flow control precision and stability. The present application is further described in detail as follows.

[0026] Embodiment 1 The flow control method provided by the present application, with reference to Figure 1 , comprises the following steps: S1, setting a linear relationship between valve opening degree and instantaneous cross-sectional area; the S1 specifically comprises the following steps: setting the cross section of the ball valve's flow hole as a rectangle, the long side of the rectangle is perpendicular to the rotation axis of the ball valve mechanism, and the instantaneous cross-sectional area Wherein I s is the current valve opening degree, I max is the maximum valve opening degree, a is the length of the long side of the rectangle, and b is the length of the short side of the rectangle. The ball valve flow hole in the present application adopts a rectangular structure, which is an optimized design. The shape of the rectangle is regular, and it is convenient to establish an accurate mathematical model to describe the relationship between valve opening degree and instantaneous cross-sectional area. Of course, in some special cases, an oval shape or other shapes can be used to replace the rectangular flow hole, but the rectangular flow hole is more convenient in calculating and realizing the linear relationship. When the rectangular flow hole is adopted, the long side is perpendicular to the rotation axis of the ball valve mechanism, so that the change relationship between the opening degree and the cross-sectional area can be more intuitively reflected when the valve is rotated.

[0027] S2, presetting several continuous instantaneous flow intervals under a set fluid pressure, testing to obtain the valve opening degree corresponding to the maximum instantaneous flow and the minimum instantaneous flow of each instantaneous flow interval, obtaining the minimum flow rate and the maximum flow rate of each instantaneous flow interval according to the linear relationship between the valve opening degree and the instantaneous cross-sectional area, and obtaining an instantaneous flow interval-valve opening degree-flow rate interval table; the instantaneous flow nodes are set at the same interval or set at a specific interval according to a specific working condition; for example, in chemical production, different chemical reactions have different requirements for fluid flow, and by presetting appropriate instantaneous flow intervals, the production demand can be better met. The continuous instantaneous flow intervals can be set at the same interval, such as setting an interval every 1 L / h; or set at a specific interval according to a specific working condition, such as using a smaller interval in a smaller flow range and a larger interval in a larger flow range in some processes sensitive to flow changes.

[0028] S3, selecting the valve opening degree corresponding to the minimum instantaneous flow of the previous interval of the flow rate interval where the expected flow rate is located as the initial adjustment opening degree, fully opening the valve to the initial adjustment opening degree, and then stopping the valve adjustment; the S3 specifically includes the following steps: First, it is judged whether the current flow rate is greater than the expected flow rate, if yes, the valve is fully closed, if not, the valve opening degree corresponding to the minimum instantaneous flow of the previous interval of the flow rate interval where the expected flow rate is located is selected as the initial adjustment opening degree, the valve is fully opened to the initial adjustment opening degree, and then the valve adjustment is stopped. The current flow rate V s = Q s / A s , wherein Q s is the measured current flow, Q s is the instantaneous cross-sectional area under the current valve opening degree I s , and the expected flow rate is a set input value. When the flow rate interval where the expected flow rate is located is the first, the initial adjustment opening degree is equal to 0. For example, in a liquid conveying system, if the current flow rate is too large and exceeds the expected flow rate, the valve is first closed and the adjustment is restarted, which can avoid damage to the system caused by excessive flow. Selecting an appropriate initial adjustment opening degree can make the subsequent adjustment process faster and more accurate to reach the expected flow rate. The continuous instantaneous flow interval of the S3 includes [0, Q1), [Q1, Q2),..., [Q n-1 , Q n ), [Q n , Q max ], wherein Q max is the maximum flow corresponding to the maximum opening, and Q i (i=1, 2,..., n) is the instantaneous flow node for dividing the interval.

[0029] S4, subtract the current flow from the expected flow to obtain the flow to be adjusted, and calculate the valve remaining opening degree according to the flow to be adjusted; this step is an accurate calculation based on the various relationships set and the data obtained, and the valve remaining opening degree is accurately calculated to provide a basis for subsequent step adjustment.

[0030] S5, step adjustment is performed according to 5%-10% of the valve remaining opening degree until the current flow is greater than or equal to the expected flow, and the valve scheduling is stopped. This step adjustment method can avoid over-adjustment and make the flow adjustment more stable. For example, in a small water circulation system, the water flow can be accurately adjusted to the expected value by this step adjustment method, avoiding the situation of large and small flow.

[0031] The present application briefly includes the steps of setting relationships, obtaining a comparison table, determining an initial opening degree, calculating a remaining opening degree, and step adjustment, wherein the linear relationship between the valve opening degree and the instantaneous cross-sectional area is set, the instantaneous flow interval-valve opening degree-flow rate interval comparison table is obtained, the initial adjustment opening degree is determined, the remaining opening degree is calculated, and the step adjustment is performed, so that the flow can be efficiently and accurately controlled, and the effect of linear flow regulation is achieved. The reason is that this method fully considers the relationship between the valve opening degree, the instantaneous cross-sectional area, and the flow rate, and reduces the error and fluctuation in the flow adjustment process through reasonable step setting and data calculation. The present application has efficient measurement and adjustment processing logic. Under the rated fluid pressure, a plurality of opening degrees are preset for a plurality of different instantaneous flows. The plurality of different instantaneous flows and opening degrees are tabulated in the microcontroller from small to large, and the instantaneous flow and the opening degree phase are substantially linear within the plurality of preset opening degrees.

[0032] The implementation principle of the embodiment is that the flow control method sets a linear relationship between the valve opening degree and the instantaneous cross-sectional area, combines the test data of different instantaneous flow intervals, establishes a perfect comparison table, and then realizes accurate linear control of the flow through a series of judgment and calculation steps. Compared with the traditional flow control method, it reduces human error and flow adjustment fluctuation, improves the accuracy and stability of flow control, and better meets the flow control needs in various industrial production and daily life.

[0033] Embodiment 2: The difference between this embodiment and the above-mentioned embodiments is that the step of determining the initial opening degree is optimized. In some systems that are not sensitive to flow changes, this judgment step can be omitted, and the valve opening degree corresponding to the minimum instantaneous flow of the flow interval before the expected flow interval is directly selected as the initial adjustment opening degree. This can simplify the adjustment process and improve the adjustment efficiency.

[0034] The implementation principle of this embodiment is as follows: In some specific application scenarios, the step of judging the current flow rate and the expected flow rate is omitted. Although this may increase the initial error of the adjustment to some extent, it is acceptable because these scenarios are less sensitive to changes in flow rate. The simplified steps reduce unnecessary calculations and judgments, speed up the flow adjustment, improve the overall system efficiency, and can still meet the flow control requirements in these scenarios.

[0035] Example 3: This application provides a flow control device, which is referenced in the embodiments of the present application. Figure 2 ,include: The ultrasonic measuring pipe section 1 is equipped with a temperature acquisition sensor 8 for collecting fluid temperature and an ultrasonic measuring component for collecting instantaneous fluid flow rate. The valve control assembly includes a ball valve 2 installed in a water outlet pipe section connected to the outlet of the ultrasonic measuring pipe section 1, a valve stem 3 for controlling the rotation of the ball valve, and a drive motor 4 for driving the rotation of the valve stem 3. The valve stem 3 passes through the water outlet pipe section and is connected to the drive motor 4. A sealing ring 5 is provided on the valve stem 3. The cross-section of the drain hole of the ball valve 2 is rectangular, and the long side of the rectangle is perpendicular to the rotation axis of the valve stem 3. The PCB control board 6 is equipped with a motor drive circuit electrically connected to the drive motor 4, a temperature acquisition circuit electrically connected to the temperature acquisition sensor 8, and an ultrasonic measurement circuit electrically connected to the ultrasonic measurement component. The drive motor 4 is a high-resolution Hall encoder motor, and the output end of the Hall encoder motor is equipped with an encoder to provide a position feedback signal. The encoder outputs positioning information through AB phase signals.

[0036] This invention employs a high-resolution actuator to improve the accuracy of valve angle control. When the AB-phase Hall encoder motor is running at full speed, the actuator takes approximately 10 seconds to open or close once, generating 12,000 AB phase signals. This precise phase signal plays a crucial role in the accurate positioning of the valve. This precise valve positioning ultimately enables this invention to achieve a flow rate adjustment range of 0.01 L / h.

[0037] Power supply 7 provides power to the entire device; the drive motor 4, PCB control board 6, and power supply 7 are all housed inside the casing fixed above the water outlet pipe section and the ultrasonic measuring pipe section 1.

[0038] The PCB control board 6 is equipped with a position feedback module, which is electrically connected to the encoder and is used to transmit the actual opening information of the bleed hole back to the controller to correct the linear relationship data table. The motor drive circuit includes a PWM signal generator and a current feedback unit. The PWM signal generator adjusts the speed of the drive motor 4 according to the pulse width modulation signal output by the controller.

[0039] The ultrasonic measurement assembly includes an ultrasonic transducer and a reflector bracket. The ultrasonic transducer is disposed on the inner wall of the fluid pipe, and the reflector bracket is fixed inside the fluid pipe to form a reflection path. The temperature sensor is used to detect the fluid temperature and compensate for the measurement error of the ultrasonic transducer. Unlike traditional mechanical flow meters, ultrasonic flow meters can measure instantaneous flow in real time without time lag, enabling rapid adjustment of instantaneous flow. The cross-section of the drain hole of ball valve 2 is rectangular, with the long side of the rectangle perpendicular to the rotation axis of valve stem 3. This invention adjusts the valve structure to solve the flow nonlinearity problem. By adjusting the shape of the ball valve drain hole, the size of the drain hole opens or closes proportionally when different opening degrees are executed, thereby achieving linear control.

[0040] The PCB control board includes a motor drive circuit electrically connected to the drive motor, a temperature acquisition circuit electrically connected to the temperature sensor, and an ultrasonic measurement circuit electrically connected to the ultrasonic measurement components. The motor drive circuit includes a PWM signal generator and a current feedback unit. The PWM signal generator adjusts the drive motor speed based on the pulse width modulation signal output by the controller. The PCB control board also includes a position feedback module, electrically connected to an encoder, used to transmit the actual opening information of the bleed orifice back to the controller to correct the linearity data table. Through these circuits and modules, the PCB control board can comprehensively control and manage the entire device, achieving precise flow regulation.

[0041] The power supply provides power to the entire device. The drive motor, PCB control board, and power supply are all housed inside the casing, which is fixed above the water outlet pipe section and the ultrasonic measuring pipe section. This layout protects each component from the influence of the external environment and also facilitates the installation and maintenance of the device.

[0042] The implementation principle of this embodiment is as follows: The flow control device, through the coordinated operation of its components, uses ultrasonic measuring tubes to accurately measure flow rate in real time. The valve control component precisely adjusts the valve opening based on the measurement results. The PCB control board intelligently controls and processes data throughout the adjustment process, and the power supply provides stable energy support, thus achieving efficient and precise flow control. Compared with traditional flow control devices, it employs advanced measurement and control technologies, solves the problem of flow nonlinearity, improves the accuracy and stability of flow control, and meets the higher requirements of modern industry for flow control.

[0043] Example 4: The difference between this embodiment and the previous embodiment is that the drive motor can be replaced by other types of high-precision motors, such as servo motors. Servo motors have the characteristics of fast response speed and high control precision, and can better meet the needs in some scenarios with high requirements for flow regulation speed.

[0044] The implementation principle of this embodiment is as follows: In specific application scenarios, a servo motor is used to replace the high-resolution Hall-coded motor. Although this may change the operating characteristics of the device in some aspects, the inherent advantages of the servo motor can improve the speed and accuracy of flow regulation, better adapting to the needs of these scenarios. This alternative solution, while ensuring the basic functions of the device, has been optimized according to different application requirements, thus broadening the applicability of the device.

[0045] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A flow control method, characterized in that, Includes the following steps: S1 sets the linear relationship between valve opening and instantaneous cross-sectional area; S2, Under a set fluid pressure, several consecutive instantaneous flow ranges are preset. The valve opening corresponding to the maximum and minimum instantaneous flow values ​​of each instantaneous flow range is obtained by testing. Based on the linear relationship between valve opening and instantaneous cross-sectional area, the minimum and maximum flow velocities of each instantaneous flow range are obtained, resulting in a reference table of instantaneous flow range - valve opening - flow velocity range. S3, select the valve opening corresponding to the minimum instantaneous flow rate of the previous velocity range of the expected flow rate range as the initial adjustment opening, open the valve to the initial adjustment opening at full speed, and then stop valve adjustment; S4, subtract the current flow from the expected flow to obtain the flow to be adjusted, and calculate the remaining valve opening based on the flow to be adjusted; S5, adjusts in steps according to 5%-10% of the remaining valve opening, until the current flow rate is greater than or equal to the expected flow rate, then stops valve scheduling.

2. The flow control method according to claim 1, characterized in that, S1 specifically includes the following steps: setting the cross-section of the vent hole of the ball valve to be rectangular, with the long side of the rectangle perpendicular to the rotation axis of the ball valve mechanism, and the instantaneous cross-sectional area... Among them I s For the current valve opening, I max denoted as the maximum valve opening, 'a' is the length of the long side of the rectangle, and 'b' is the length of the short side of the rectangle.

3. The flow control method according to claim 2, characterized in that, Before step S3, the following steps are included: determine whether the current flow rate is greater than the expected flow rate. If yes, completely close the valve and proceed to step S3; otherwise, proceed to step S3.

4. The flow control method according to claim 1, characterized in that, In S3, when the expected flow velocity is in the first flow velocity range, the initial adjustment opening is equal to 0.

5. The flow control method according to claim 1, characterized in that, The continuous instantaneous flow range of S3 includes [0, Q1), [Q1, Q2), ..., [Q1, Q2]. n-1 Q n ), [Q n Q max ], where Q max Q represents the maximum flow rate corresponding to the maximum opening. i (i = 1, 2, ..., n) are the instantaneous flow nodes of the interval.

6. The flow control method according to claim 5, characterized in that, The instantaneous flow nodes are set at the same interval or at a specific interval according to specific operating conditions.

7. A flow control device, employing the flow control method according to any one of claims 1-6, characterized in that, include: The ultrasonic measuring pipe section (1) is equipped with a temperature acquisition sensor (8) for collecting fluid temperature and an ultrasonic measuring component for collecting instantaneous fluid flow rate. The valve control assembly includes a ball valve (2) installed in a water outlet pipe section connected to the outlet of the ultrasonic measuring pipe section (1), a valve stem (3) for controlling the rotation of the ball valve, and a drive motor (4) for driving the rotation of the valve stem (3). The valve stem (3) passes through the water outlet pipe section and is connected to the drive motor (4). A sealing ring (5) is provided on the valve stem (3). The cross-section of the drain hole of the ball valve (2) is rectangular, and the long side of the rectangle is perpendicular to the rotation axis of the valve stem (3). The PCB control board (6) is provided with a motor drive circuit electrically connected to the drive motor (4), a temperature acquisition circuit electrically connected to the temperature acquisition sensor (8), and an ultrasonic measurement circuit electrically connected to the ultrasonic measurement component. Power supply (7) provides power to the entire device; The drive motor (4), PCB control board (6), and power supply (7) are all housed inside the casing fixed above the water outlet pipe section and the ultrasonic measuring pipe section (1).

8. A flow control device according to claim 7, characterized in that, The drive motor (4) is a high-resolution Hall encoder motor. The output end of the Hall encoder motor is equipped with an encoder to provide position feedback signals. The encoder outputs positioning information through AB phase signals.

9. A flow control device according to claim 8, characterized in that, The PCB control board (6) is provided with a position feedback module, which is electrically connected to the encoder and is used to transmit the actual opening information of the bleed hole back to the controller to correct the linear relationship data table.

10. A flow control device according to claim 8, characterized in that, The motor drive circuit includes a PWM signal generator and a current feedback unit. The PWM signal generator adjusts the speed of the drive motor (4) according to the pulse width modulation signal output by the controller.

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