Multi-channel liquid small-flow control system and control method thereof

Abstract

The invention provides a multi-channel liquid small-flow control system which comprises a pump, a glass rotor flow meter, a metal shielding box, a liquid flow controller, a pressure transmitter, a data acquisition card and a computer. The liquid flow controller, the pressure transmitter and the data acquisition card are all arranged in the metal box shield, interference of factors such as an external magnetic field and an external electric field can be shielded, and the liquid flow controller is connected with the glass rotameter and the pressure transmitter. The pressure transmitter is connected with the liquid flow controller, the data acquisition card is connected with the liquid flow controller and the pressure transmitter, the computer is connected with the data acquisition card, and the multi-channel liquid small-flow control system can conveniently and accurately measure and adjust the liquid flow in the channels in real time. In addition, the invention further provides a control method of the multi-channel liquid small-flow control system.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid flow measurement and control, and in particular to a multi-channel liquid small flow control system and a control method thereof. Background Art

[0002] With the gradual development of fluid systems towards miniaturization, micro-flow has been widely used in many high-tech fields, such as aerospace, semiconductors, biology, medicine, energy, chemical industry, etc., and the demand for micro-flow in these fields is also increasing. Micro-flow refers to the flow rate in the flow channel from a few milliliters to hundreds of milliliters per minute under steady flow conditions. Micro-flow control can be divided into flow measurement and flow regulation, among which micro-flow measurement requires high accuracy, and micro-flow regulation also requires high control accuracy. Because in most industrial production, the consumption is determined by measuring and regulating micro-flow, and the production process is automated and optimally controlled. Therefore, realizing the measurement and automatic regulation of micro-flow can not only effectively reduce production costs but also improve production efficiency. If micro-flow control can be achieved on multiple channels, production efficiency can be doubled. However, micro-flow measurement and automatic regulation are still a technical problem in fluid flow.

[0003] There are many types of measurement methods and instruments for micro-flow, and there are many classification methods. For example, electromagnetic flowmeters are suitable for flow measurement of conductive liquids, but there are large errors when measuring the flow of non-conductive liquids, and they are not suitable for micro-flow measurement. Ultrasonic flowmeters have the characteristics of low pressure loss and wide measurement range, but they have clear requirements for liquid types and cannot contain bubbles. The characteristics of vortex flowmeters are small pressure loss and large range. When the fluid flow is small, the measurement error is large, deviations are prone to occur, and some cannot be used at all when the liquid is more special. Therefore, it is difficult to directly apply commonly used flow meters to the measurement of micro-flow. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes a multi-channel liquid small flow control system and a control method thereof, which has high precision, rapid response and good stability, and can realize the measurement and real-time adjustment of multi-channel small flow.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a multi-channel liquid small flow control system, including a pump, a glass rotor flowmeter, a metal shielding box, a liquid flow controller, a pressure transmitter, a data acquisition card and a computer, the glass rotor flowmeter is connected to the pump, the liquid flow controller, the pressure transmitter and the data acquisition card are all arranged in the metal shielding box, which can shield the interference of external magnetic fields, electric fields and other factors, the liquid flow controller is connected to the glass rotor flowmeter and the pressure transmitter, the data acquisition card is connected to the liquid flow controller and the pressure transmitter, and the computer is connected to the data acquisition card.

[0006] Furthermore, the glass rotor flowmeter has a valve needle with an adjustable opening, which can roughly adjust the liquid flow in the channel.

[0007] Furthermore, the liquid flow controller includes a laminar pressure differential flowmeter, a controller and a proportional control valve. The laminar pressure differential flowmeter utilizes a laminar flow element to separate the turbulent flow passing through it into a series of thin and parallel channels, and then converts it into laminar flow, and then measures the fluid flow through the pressure drop generated inside the laminar flow element. The controller is connected to the laminar pressure differential flowmeter.

[0008] Furthermore, the controller in the liquid flow controller automatically determines in real time whether the current measured flow is equal to the set flow. If the measured flow is not equal to the set flow, the controller will send a feedback signal to the proportional control valve to adjust its opening degree, thereby adjusting the liquid flow to reach the set flow.

[0009] In a second aspect, the present invention further provides a control method for a multi-channel liquid small flow control system, comprising the following steps: Step 1: The liquid is pumped to the main channel and then diverted to eight channels through an integrated eight-way diverter; Step 2: Install a glass rotor flowmeter, a liquid flow controller, and a pressure transmitter in each liquid flow channel in sequence; Step 3: Open the connection and run the host computer software system, and set and confirm the liquid flow value in each channel in the system; Step 4: The software system uses the data acquisition card to collect the liquid flow controller and The pressure transmitter measures the liquid flow and pressure in the flow channel and displays the curve in real time; Step 5: The system can control the proportional control valve in real time through the liquid flow controller to adjust its opening to obtain the set flow value.

[0010] Furthermore, the software system can independently set the liquid flow rates on the eight pipelines according to requirements, thereby achieving the same liquid flow rate or online variable in each pipeline.

[0011] Furthermore, the software system collects the liquid flow value and pressure value in the flow channel measured by the liquid flow controller and the pressure transmitter on each channel in real time through a data acquisition card, and displays the flow and pressure in real time curves on the main interface.

[0012] The multi-channel liquid small flow control system and control method of the present invention, the flow control device performs real-time online detection and control of the liquid flow through the liquid flow controller, and the control method realizes automatic adjustment of the flow in the channel based on the closed-loop control principle. The multi-channel liquid small flow control system and control method of the present invention have the advantages of high precision, high resolution, rapid response, good stability, no influence of strong magnetic fields, strong anti-disturbance ability, and have wide applicability, and can be applied to the technical fields of medicine, agriculture, biology, hydraulics, etc., especially for some multi-target flow synchronization control and regulation, which has strong application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of a multi-channel liquid small flow control system; Figure 2 It is a control flow diagram of a multi-channel liquid small flow control system; Figure 3 It is a schematic diagram of the closed-loop control process of a multi-channel liquid small flow control system; In the figure: 1. Pump, 2. Glass rotor flowmeter, 3. Liquid flow controller, 4. Pressure transmitter, 5. Data acquisition card, 6. Computer, 7. Metal shielding box. DETAILED DESCRIPTION

[0014] See also Figure 1-Figure 3 In the first aspect, the present invention provides a multi-channel liquid small flow control system, including a pump 1, a glass rotor flowmeter 2, a metal shielding box 7, a liquid flow controller 3, a pressure transmitter 4, a data acquisition card 5 and a computer 6, wherein the glass rotor flowmeter is connected to the pump, the liquid flow controller, the pressure transmitter and the data acquisition card are all arranged in the metal shielding box, which can shield the interference of external magnetic fields, electric fields and other factors, the liquid flow controller is connected to the glass rotor flowmeter and the pressure transmitter, the data acquisition card is connected to the liquid flow controller and the pressure transmitter, and the computer is connected to the data acquisition card.

[0015] Furthermore, the glass rotor flowmeter has a valve needle with adjustable opening.

[0016] Furthermore, the liquid flow controller includes a laminar pressure differential flowmeter, a controller and a proportional control valve. The laminar pressure differential flowmeter utilizes a laminar flow element to separate the turbulent flow passing through it into a series of thin and parallel channels, and then converts it into laminar flow, and then measures the fluid flow through the pressure drop generated inside the laminar flow element. The controller is connected to the laminar pressure differential flowmeter.

[0017] Furthermore, the controller in the liquid flow controller automatically determines in real time whether the current measured flow is equal to the set flow. If the measured flow is not equal to the set flow, the controller will send a feedback signal to the proportional control valve to adjust its opening degree, thereby adjusting the liquid flow to reach the set flow.

[0018] In a second aspect, the present invention further provides a control method for a multi-channel liquid small flow control system, comprising the following steps: Step 1: The liquid is pumped to the main channel and then diverted to eight channels through an integrated eight-way diverter; Step 2: Install a glass rotor flowmeter, a liquid flow controller, and a pressure transmitter in each liquid flow channel in sequence; Step 3: Open the connection and run the host computer software system, and set and confirm the liquid flow value in each channel in the system; Step 4: The software system uses the data acquisition card to collect the liquid flow controller and The pressure transmitter measures the liquid flow and pressure in the flow channel and displays the curve in real time; Step 5: The system can control the proportional control valve in real time through the liquid flow controller to adjust its opening to obtain the set flow value.

[0019] Furthermore, the software system can independently set the liquid flow rates on the eight pipelines according to requirements, thereby achieving the same liquid flow rate or online variable in each pipeline.

[0020] Furthermore, the software system collects the liquid flow value and pressure value in the flow channel measured by the liquid flow controller and the pressure transmitter on each channel in real time through a data acquisition card, and displays the flow and pressure in real time curves on the main interface.

[0021] Among them, when this system controls the liquid flow, the glass rotor flowmeter can roughly control the liquid flow entering the flow channel by adjusting the opening of its internal needle valve, and the approximate value of the liquid flow can also be directly observed through the glass tube. When the liquid is pressed into the integrated eight-way diverter by the pump, it is diverted into eight branches, and then enters the glass rotor flowmeter of each branch through each branch. In this way, you can directly observe the flow scale on the glass tube to roughly read its flow, manually adjust the position of the needle valve core to adjust the valve opening, and realize flow control until it reaches the required flow (generally slightly larger than the set flow). In addition, the glass rotor flowmeter also has strong corrosion resistance and can be used to adjust the flow of corrosive liquids.

[0022] Among them, the liquid flow controller used in this system is mainly composed of three components, including a laminar pressure differential flowmeter, a controller and a proportional control valve. The laminar pressure differential flowmeter uses laminar flow elements to separate the turbulent flow into a series of thin and parallel channels, converts it into laminar flow, and then measures the fluid flow through the pressure drop generated inside the laminar flow element. Moreover, the laminar pressure differential flowmeter can compensate for the physical properties of the medium according to the actual working conditions and realize the accurate measurement of the liquid flow in the pipeline. The controller compares the flow value detected by the laminar pressure differential flowmeter with the set value and outputs a feedback signal to the proportional control valve. The proportional control valve adopts a non-contact drive and a magnetic coupling system with high durability and high pressure resistance. Therefore, the liquid flow controller used in this system can not only accurately detect the liquid flow, but also maintain a stable liquid flow.

[0023] Among them, the software system is the core part of this system, which can realize functions such as data acquisition and data processing. The system software is written based on LabVIEW software and is designed using a modular approach. It is mainly divided into the following modules: board initialization and parameter setting module, flow setting module, data acquisition module, data processing and display module. Each module is defined and standardized in the system software, so that scalability changes in one module will not affect other modules in the program. These modules are independent in function and are interconnected in the software program, thereby increasing the flexibility of the software system. Therefore, the software system of the present invention not only increases the flexibility of the system software through a modular approach, but also can carry out secondary development of the software system.

[0024] Among them, the liquid flow rates on eight pipelines can be independently set in the software system according to the needs, and multiple task goals can be achieved and regulated synchronously at the same time. According to the needs in actual production, the flow rates on each channel can be independently set in the software system. Each branch in the system operates independently of each other, and the branches do not interfere with each other. Different industries have different requirements for liquid flow control. The system can be set to different flow values ​​according to the needs of each branch, and can also be set to the same flow value. The use of the present invention can significantly improve the flexibility and applicability of multi-channel small flow control.

[0025] Among them, the flow rate and pressure in the channel are displayed and monitored in real time on the main interface of the software system. After the system hardware is powered on, the host computer software system collects data from the liquid flow controller and pressure transmitter in the channel in real time through the data acquisition card, and then performs subsequent data processing in the software system to obtain the liquid flow value and pressure value on each channel. The flow rate and pressure in the channel can be displayed in real time on the main interface of the software system, which is convenient for real-time monitoring of flow rate and pressure.

[0026] Among them, the liquid flow controller can maintain a stable liquid flow in real time. The laminar flow meter first accurately measures the liquid flow of the flow channel, and then the controller continuously compares the measured flow with the set flow. When the detected fluid flow is greater than the set flow, the controller converts the difference between the two into a feedback signal and sends it to the proportional control valve, adjusts the valve core position downward to reduce its opening, thereby reducing the fluid flow in the pipeline; when the detected fluid flow is less than the set flow, the controller converts the difference between the two into a feedback signal and sends it to the proportional control valve, adjusts the valve core position upward to increase its opening, thereby increasing the fluid flow in the pipeline. In this way, it is continuously adjusted until the actual flow in the pipeline matches the set flow. Therefore, the liquid flow controller is a closed-loop control for flow control, which can realize fluid flow measurement and automatic and precise adjustment, so that it can maintain a stable liquid flow.

[0027] Among them, except for the glass rotor flowmeter, the rest of the hardware in this system is installed in a stainless steel metal box, which can resist the interference of electromagnetic fields. The liquid flow controller, pressure transmitter, terminal block, data acquisition card and other hardware used in this system are installed in a metal shielding box, so that the metal shielding protection layer formed can effectively shield the interference of external magnetic fields, electric fields and other factors to a certain extent. Therefore, this system has the advantages of strong resistance to electromagnetic field influence and anti-disturbance ability.

[0028] The multi-channel liquid small flow control system and control method of the present invention, the flow control device performs real-time online detection and control of the liquid flow through the liquid flow controller, and the control method realizes automatic adjustment of the flow in the channel based on the closed-loop control principle. The multi-channel liquid small flow control system and control method of the present invention have the advantages of high precision, high resolution, rapid response, good stability, no influence of strong magnetic fields, strong anti-disturbance ability, and have wide applicability, and can be applied to the technical fields of medicine, agriculture, biology, hydraulics, etc., especially for some multi-target flow synchronization control and regulation, which has strong application value.

[0029] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not limited to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-channel liquid small flow control system, characterized in that: It includes a pump, a glass rotor flowmeter, a metal shielding box, a liquid flow controller, a pressure transmitter, a data acquisition card and a computer. The glass rotor flowmeter is connected to the pump, the liquid flow controller, the pressure transmitter and the data acquisition card are all arranged in the metal shielding box, which can shield external magnetic field and electric field factors. The liquid flow controller is connected to the glass rotor flowmeter and the pressure transmitter, the data acquisition card is connected to the liquid flow controller and the pressure transmitter, and the computer is connected to the data acquisition card.

2. The multi-channel liquid small flow control system according to claim 1, characterized in that: The glass rotor flowmeter has a valve needle with an adjustable opening, which can directly read the liquid flow value and can also roughly adjust the liquid flow in the channel.

3. The multi-channel liquid small flow control system according to claim 1, characterized in that: The liquid flow controller includes a laminar pressure differential flowmeter, a controller and a proportional control valve. The laminar pressure differential flowmeter uses a laminar flow element to separate the turbulent flow into a series of thin and parallel channels, and then converts it into laminar flow, and then measures the fluid flow through the pressure drop generated inside the laminar flow element. The controller is connected to the laminar pressure differential flowmeter.

4. The multi-channel liquid small flow control system according to claim 1, characterized in that: The controller in the liquid flow controller automatically determines in real time whether the current measured flow is equal to the set flow. If the measured flow is not equal to the set flow, the controller will send a feedback signal to the proportional control valve to adjust its opening degree, thereby adjusting the liquid flow to reach the set flow.

5. A control method for a multi-channel liquid small flow control system, characterized in that: The following steps are involved: Step 1: The liquid is pumped to the main channel and then diverted to eight channels through an integrated eight-way diverter; Step 2: Install a glass rotor flowmeter, a liquid flow controller, and a pressure transmitter in each liquid flow channel in sequence; Step 3: Open the connection and run the host computer software system, and set and confirm the liquid flow value in each channel in the system; Step 4: The software system uses the data acquisition card to collect the liquid flow controller and The pressure transmitter measures the liquid flow and pressure in the flow channel and displays the curve in real time; Step 5: The system can control the proportional control valve in real time through the liquid flow controller to adjust its opening to obtain the set flow value.

6. The control method of the multi-channel liquid small flow control system according to claim 5, characterized in that: The software system independently sets the liquid flow rates on eight pipelines according to requirements, thereby achieving the same or online variable liquid flow rates in each pipeline.

7. The control method of the multi-channel liquid small flow control system according to claim 6, characterized in that: The software system collects the liquid flow value and pressure value in the flow channel measured by the liquid flow controller and the pressure transmitter on each channel in real time through a data acquisition card, and displays the liquid flow and liquid pressure in real time curves on the main interface.

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