A constant pressure control system for a pressure vessel

Abstract

The present disclosure relates to a pressure container constant pressure control system, which comprises a pressure container, a pressure detection sensor and a control unit. The pressure detection sensor is used to detect the pressure of the pressure container and output a pressure signal in real time. The control unit comprises a control terminal and an actuator. The control terminal is used to generate a control signal according to the pressure signal. The actuator comprises a first proportional valve and a second proportional valve connected in series. The first proportional valve and the second proportional valve are used to simultaneously control the air intake and exhaust of the pressure container according to the control signal. By setting the air intake and exhaust proportional valves in series, using one control algorithm to control the two proportional valves, the present disclosure avoids the waste of resources and can realize accurate control and adjustment of the system pressure. At the same time, the use of two control algorithms to control the air intake and exhaust respectively is avoided, which leads to poor control effect.

Description

Technical Field

[0001] This disclosure relates to the field of automation control technology, and in particular to a constant pressure control system for pressure vessels. Background Technology

[0002] A constant pressure control system for pressure vessels is a system used to maintain a constant internal pressure within a pressure vessel. By adjusting the internal pressure of the pressure vessel, it ensures that the internal pressure remains stable at a set value.

[0003] Current constant pressure control systems for pressure vessels achieve the set pressure by controlling the intake proportional valve and opening the exhaust valve to release overpressured gas when the pressure exceeds the set limit. This control method leads to pressure fluctuations, negatively impacting the stability and performance of the control system. Some constant pressure control systems for pressure vessels use two control algorithms, one for the intake and one for the exhaust proportional valve. However, this requires more control resources, and the two algorithms may interfere with or conflict with each other, resulting in poor control performance. Summary of the Invention

[0004] To address the aforementioned technical problems of poor stability and inadequate control performance in constant pressure control systems for pressure vessels, this disclosure proposes a constant pressure control system for pressure vessels, comprising:

[0005] Pressure vessels, pressure sensors, and control units;

[0006] The input terminal of the pressure detection sensor is connected to the pressure vessel to detect the pressure of the pressure vessel and output a pressure signal in real time.

[0007] The input terminal of the control unit is connected to the output terminal of the pressure detection sensor, and the output terminal of the control unit is connected to the pressure vessel.

[0008] The control unit includes a control terminal and an actuator. The control terminal and the actuator are electrically connected. The control terminal is used to generate a control signal based on the pressure signal. The actuator is used to control the air intake and exhaust volume in the pressure vessel in real time based on the control signal, so that the pressure of the pressure vessel is maintained at a preset pressure value.

[0009] The actuator includes a first proportional valve and a second proportional valve, the first proportional valve and the second proportional valve being connected in series. The first proportional valve is used to control the air intake of the pressure vessel, and the second proportional valve is used to control the air exhaust of the pressure vessel.

[0010] In a further embodiment, the control terminal includes a programmable logic controller (PLC), which is used to input the pressure signal and the preset pressure value into a control algorithm, execute the control algorithm, and generate the control signal.

[0011] In a further embodiment, the control unit further includes an analog input module and an analog output module, wherein the analog input module is used to convert the pressure signal into a digital signal, and the analog output module is used to convert the control signal into a current signal and output it.

[0012] In a further embodiment, the analog output module includes a signal output channel with positive and negative terminals. The signal output channel is used to output the control signal, which has a range of 4 mA to 20 mA.

[0013] In a further embodiment, the first proportional valve and the second proportional valve are respectively provided with positive and negative terminals. The positive terminal of the first proportional valve is connected to the negative terminal of the signal output channel, the negative terminal of the first proportional valve is connected to the positive terminal of the second proportional valve, and the negative terminal of the second proportional valve is connected to the positive terminal of the signal output channel.

[0014] In a further embodiment, the opening degree of the first proportional valve from 0 to 100% is mapped to the range of 12 mA to 20 mA of the control signal to control the intake air volume of the pressure vessel, and the opening degree of the second proportional valve from 0 to 100% is mapped to the range of 12 mA to 4 mA of the control signal to control the exhaust air volume of the pressure vessel.

[0015] In a further embodiment, the control algorithm is a proportional-integral-derivative algorithm, used to calculate and generate the control signal based on the difference between the pressure signal and the preset pressure value.

[0016] This disclosure also provides a constant pressure control method for a pressure vessel, the method being applied to the aforementioned constant pressure control system for a pressure vessel, the method comprising:

[0017] Based on the pressure sensor of the pressure vessel constant pressure control system, the pressure signal of the pressure vessel of the pressure vessel constant pressure control system is acquired in real time.

[0018] The control unit of the pressure vessel constant pressure control system generates a control signal based on the pressure signal, and controls the air intake and exhaust volume of the pressure vessel in real time based on the control signal, so that the pressure of the pressure vessel is maintained at a preset pressure value.

[0019] In a further embodiment, the control unit based on the constant pressure control system of the pressure vessel generates a control signal according to the pressure signal, including:

[0020] Based on the control terminal in the control unit, the pressure signal and the preset pressure value are input into the proportional-integral-derivative control algorithm, and the proportional-integral-derivative control algorithm is executed to obtain the control signal. The control signal is a current signal, and the range of the control signal is from 4 mA to 20 mA.

[0021] In a further embodiment, the step of controlling the air intake and exhaust volume of the pressure vessel in real time according to the control signal includes:

[0022] When the control signal is 12 mA, the first proportional valve and the second proportional valve of the actuator in the control unit are closed, and the pressure vessel does not perform air intake and exhaust operations.

[0023] When the control signal increases from 12 mA to 20 mA, the opening of the first proportional valve gradually increases from 0 to 100%, and the pressure vessel performs an air intake operation.

[0024] When the control signal decreases from 12 mA to 4 mA, the opening of the second proportional valve gradually increases from 0 to 100%, and the pressure vessel performs an venting operation.

[0025] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure.

[0026] Implementing this disclosure will have the following beneficial effects:

[0027] This disclosure, by setting up intake and exhaust proportional valves, enables precise regulation of gas intake and exhaust flow, achieving accurate control and regulation of system pressure. Furthermore, the intake and exhaust proportional valves are connected in series, allowing simultaneous control of both valves through a single control algorithm output. This requires only one algorithm loop and one control signal output channel, avoiding resource waste and preventing the mutual interference and conflict that can occur when using two separate control algorithms to control the intake and exhaust proportional valves, resulting in poor control performance. Therefore, implementing this disclosure can solve the technical problems of poor stability and ineffective control in constant pressure control systems for pressure vessels, providing a reliable and efficient pressure control solution that precisely controls and regulates pressure, saves resources, avoids conflicts and interference, and offers a superior solution.

[0028] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0029] To more clearly illustrate the technical solutions and advantages in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A schematic diagram of a pressure vessel constant pressure control system according to an embodiment of the present disclosure is shown;

[0031] Figure 2 This diagram illustrates the execution process of a constant pressure control system for a pressure vessel according to an embodiment of the present disclosure.

[0032] Figure 3 This diagram shows a structural block diagram of a control unit according to an embodiment of the present disclosure;

[0033] Figure 4 A schematic diagram showing the connection between the signal output channel and the control mechanism according to an embodiment of the present disclosure is shown;

[0034] Figure 5 A flowchart illustrating a constant pressure control method according to an embodiment of the present disclosure is shown;

[0035] Figure 6 This diagram illustrates the structure of an electronic device according to an embodiment of the present disclosure.

[0036] In the diagram: 1. Pressure vessel; 2. Pressure sensor; 3. Control unit; 31. Control terminal; 32. Actuator; 311. Programmable logic controller; 312. Analog input module; 313. Analog output module. Detailed Implementation

[0037] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or server that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0039] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0040] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0041] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0042] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0043] Many processes require specific pressures. Utilizing a pressure vessel constant pressure control system to maintain a constant pressure within the pressure vessel ensures process stability and product quality. Furthermore, ensuring stable internal pressure within the pressure vessel prevents equipment damage or accidents caused by excessively high or low pressure.

[0044] Please refer to the attached instruction manual. Figure 1 It illustrates a constant pressure control system for a pressure vessel according to an embodiment of the present disclosure, such as... Figure 1As shown, the pressure vessel constant pressure control system includes:

[0045] Pressure vessel 1, pressure sensor 2, and control unit 3;

[0046] The input end of the pressure sensor 2 can be connected to the pressure vessel 1 via a threaded connection, flange connection, or welded connection, etc., to detect the pressure of the pressure vessel 1 and output a pressure signal in real time. The pressure signal is an electrical signal, and its form may vary depending on the type and design of the pressure sensor 2. The pressure vessel 1 can be various types of containers or systems, such as gas tanks, oil tanks, water tanks, pipeline systems, etc. Using the pressure sensor 2 can help the system accurately control the pressure inside the pressure vessel 1. Common pressure sensors include piezoresistive sensors, capacitive sensors, and piezoelectric sensors, etc. These pressure sensors are selected for use in different application scenarios. In the various embodiments according to this disclosure, a suitable pressure sensor can be selected based on factors such as pressure range, accuracy requirements, and working environment.

[0047] The input terminal of the control unit 3 is connected to the output terminal of the pressure sensor 2, and the output terminal of the control unit 3 is connected to the pressure vessel 1. The control unit 3 typically includes components such as a microprocessor, memory, and input / output interfaces. The control unit 3 is connected to the pressure sensor 2 and the pressure vessel 1 via appropriate cables or wires. These cables or wires contain signal transmission lines, which can transmit pressure signals from the pressure sensor 2 to the control unit 3. Simultaneously, the control unit 3 also transmits control signals back to the pressure vessel 1 via the signal transmission lines. It should be noted that the specific connection method may vary depending on the system design and equipment model.

[0048] The control unit 3 includes a control terminal 31 and an actuator 32. The control terminal 31 is typically a computer or controller used to generate control signals based on the pressure signal. The actuator 32 typically includes an intake valve, an exhaust valve, and a regulating valve, used to control the intake and exhaust volume of the pressure vessel 1 in real time according to the control signals, so that the pressure of the pressure vessel 1 is maintained at a preset pressure value. Common actuators include pressure regulating valves and EPCD electronic dual-valve pressure controllers. For example, when the pressure of the pressure vessel 1 exceeds the preset value, the pressure regulating valve will automatically open to release the excess pressure until the pressure drops to the set value. Conversely, when the pressure of the pressure vessel 1 is lower than the preset value, the pressure regulating valve will automatically open to draw in an appropriate amount of gas to raise the pressure to the preset value. The control terminal 31 and the actuator 32 are electrically connected. The control signal is transmitted to the actuator 32 using electrical equipment (such as frequency converter, PLC, etc.). Specifically, the electrical connection between the control terminal 31 and the actuator 32 can be achieved using equipment such as cables, plugs, sockets, and switches to realize information transmission and control between them. Using electrical connection can improve the control accuracy and stability of the system, increase the operating efficiency and service life of the equipment, and simplify the operation process.

[0049] In this embodiment, the control terminal 31 includes a programmable logic controller (PLC) 311. The PLC 311 receives pressure signals from the pressure sensor 2 and converts these signals into executable control signals. It inputs the pressure signals and the preset pressure value into a control algorithm, executes the algorithm, and generates the control signals. Specifically, the control terminal 31 receives real-time pressure signals from the pressure sensor 2, processes and calculates these signals through the PLC 311, and obtains corresponding control commands. These commands are sent to the actuator 32, such as an electric actuator, to induce corresponding actions that change the pressure state within the pressure vessel, ensuring the pressure remains at a set constant value. In a more preferred embodiment, the control terminal 31 and the actuator 32 can also cooperate to perform other functions, such as fault diagnosis, alarm prompts, data recording and analysis, helping operators to promptly identify and resolve problems, thereby improving production efficiency and safety.

[0050] Please refer to the attached instruction manual. Figure 2 It illustrates a schematic diagram of the execution process of a pressure vessel constant pressure control system according to an embodiment of the present disclosure, such as... Figure 2As shown, the actuator 32 includes a first proportional valve and a second proportional valve, which are connected in series. The first proportional valve is typically located at the top of the pressure vessel 1, and the second proportional valve is typically located at the bottom of the pressure vessel 1. The first and second proportional valves can be installed on the pressure vessel 1 using threaded connections, flange connections, or welding connections. The specific connection method depends on the design and operating environment of the pressure vessel 1, and this embodiment does not impose any limitations on this. The first and second proportional valves are connected in series. Through this series connection, the intake proportional valve and the exhaust proportional valve can be controlled by a single control signal. Both proportional valves can be controlled simultaneously by the output of a single control algorithm, requiring only one control algorithm loop and one output channel, reducing the number of devices and saving resources. Furthermore, the series connection minimizes the mutual influence between the first and second proportional valves, thereby improving control accuracy. In addition, compared to using two independent control algorithms to control the first and second proportional valves separately, implementing this disclosure avoids the problem of potential mutual interference and conflict between intake and exhaust, leading to poor control performance. Figure 2 As shown, in this embodiment of the present disclosure, the pressure signal of the pressure vessel 1 and the preset pressure value are used as inputs to the programmable logic controller 311. The programmable logic controller 311 generates a control signal based on the pressure signal and the preset pressure value, and adjusts the pressure of the pressure vessel 1 using the first proportional valve and the second proportional valve connected in series according to the control signal.

[0051] In this embodiment, the first proportional valve is an intake proportional valve used to control the intake volume of the pressure vessel 1, and the second proportional valve is an exhaust proportional valve used to control the exhaust volume of the pressure vessel 1. A common structure for the intake and exhaust proportional valves is a diaphragm valve, which has an adjustable diaphragm to control the airflow rate. Other common structures include ball valves, butterfly valves, etc. The actuator 32 adjusts the opening degree of the intake and exhaust proportional valves according to the control signal, thereby controlling the intake and exhaust volume in the pressure vessel 1 to maintain the set pressure level.

[0052] This embodiment of the disclosure, by setting an intake proportional valve and an exhaust proportional valve, can precisely adjust the gas intake and exhaust volume according to a set control signal, thereby achieving precise control and regulation of system pressure. The control signal is obtained from the output of a control algorithm, and the intake and exhaust proportional valves are connected in series. Both proportional valves can be controlled by the output of a single control algorithm, requiring only one algorithm loop and one output channel, avoiding resource waste and preventing the potential for mutual interference and conflict between two separate control algorithms for intake and exhaust, which could lead to poor control performance.

[0053] Figure 3 A structural block diagram of a control unit according to an embodiment of the present disclosure is shown, such as Figure 3 As shown, the control unit 31 further includes an analog input module 312 and an analog output module 313. The analog input module 312 is used to convert the pressure signal into a digital signal, and the analog output module 313 is used to convert the control signal into a current signal and output it.

[0054] Specifically, the analog input module 312 receives the pressure signal transmitted by the pressure sensor 2 and converts it into a digital signal, which is then transmitted to the central processing unit of the programmable logic controller 311 for processing. The analog output module 313 converts the digital signal processed by the central processing unit into a current signal and outputs it to the actuator 32. Since the pressure signal transmitted by the pressure sensor 2 is a continuously changing analog signal, it needs to be converted into a digital signal before it can be processed by the programmable logic controller 311. By using the analog input module 312 and the analog output module 313 to convert the pressure signal into a discrete digital signal, the amplitude of which is limited to a certain value, making it easier for the computer to process. In many cases, digital signals have stronger anti-interference capabilities, longer transmission distances, and signal stability, providing higher accuracy and stability for the system.

[0055] The analog output module 313 includes a signal output channel with positive and negative interfaces. The signal output channel is used to output the control signal, which ranges from 4 mA to 20 mA. This embodiment of the present disclosure outputs a control signal by executing a control algorithm, requiring only one digital-to-analog signal conversion. Therefore, the analog output module 313 is a single-channel output module, avoiding resource waste, reducing costs, and improving system stability and reliability. Since the resistance of the conductor has a relatively small impact on current signals, while voltage signals are divided by the resistance of the conductor itself, leading to inaccurate measurements, outputting the control signal as a current signal has stronger anti-interference capabilities compared to voltage signals. Furthermore, the 4-20mA current signal has good failure protection performance. Setting the starting point of the current signal to 4mA, rather than 0mA, prevents potential wire breakage during device wiring. If the starting point is set to 0mA, the receiving device will not receive any current signal in case of poor wiring or disconnection, making it impossible to determine whether a wire breakage has occurred. If the starting point is set to 4mA, even if a disconnection occurs, the receiving device can still obtain a 4mA current signal, which can more accurately determine whether a disconnection fault has occurred.

[0056] The first proportional valve and the second proportional valve are respectively provided with positive and negative interfaces. Figure 4 A schematic diagram showing the connection between the signal output channel and the control mechanism 32 according to an embodiment of the present disclosure is shown, as follows: Figure 4 As shown, the positive terminal of the first proportional valve is connected to the negative terminal of the signal output channel, the negative terminal of the first proportional valve is connected to the positive terminal of the second proportional valve, and the negative terminal of the second proportional valve is connected to the positive terminal of the signal output channel. This ensures a clear transmission path for the control signal, avoids signal interference, and thus improves control accuracy and stability. Furthermore, the first and second proportional valves are connected in series, allowing both to be controlled simultaneously with a single control signal. This avoids resource waste, eliminates unnecessary intermediate nodes, simplifies control system wiring, reduces the likelihood of malfunctions, and avoids the potential for interference and conflict caused by using two separate control algorithms to generate two control signals for the first and second proportional valves, resulting in poor control performance. Simultaneously, since the control signal is transmitted through a single line, implementing this disclosure allows for better monitoring of the entire control system's operating status and timely detection and resolution of problems.

[0057] The opening of the first proportional valve, from 0 to 100%, is mapped to the control signal range of 12 mA to 20 mA to control the intake air volume of the pressure vessel 1. Similarly, the opening of the second proportional valve, from 0 to 100%, is mapped to the control signal range of 12 mA to 4 mA to control the exhaust air volume of the pressure vessel 1. Specifically, the range of the control signal can be mapped to the opening ranges of the first and second proportional valves according to the desired proportional relationship through circuit design and control algorithms. For example, circuit components such as voltage proportional amplifiers and current converters can be used to ensure that changes in the control signal range of 12 mA to 20 mA are correctly mapped to the opening range of the first proportional valve from 0 to 100%. Likewise, circuits can be designed to ensure that changes in the control signal range of 12 mA to 4 mA are correctly mapped to the opening range of the second proportional valve from 0 to 100%. With appropriate circuit design and control algorithm, precise proportional control can be achieved, ensuring a linear relationship between the control signal and the opening degree of the first and second proportional valves, thereby achieving precise intake and exhaust volume control. Furthermore, by mapping the range of the control signal to the opening range of the first and second proportional valves, complex adjustment circuits and algorithms can be avoided, simplifying the system design and improving control accuracy and system performance.

[0058] In this embodiment, the control algorithm is a proportional-integral-derivative (PID) algorithm. The PID algorithm combines the advantages of proportional control, integral control, and derivative control, effectively controlling system performance. It is used to calculate and generate the control signal based on the difference between the pressure signal and the preset pressure value, and then outputs this control signal to achieve precise pressure control. It is important to note that the parameters of the PID algorithm need to be adjusted according to the actual operating conditions, as different operating conditions may require different PID parameters to achieve the best control effect. For example, under different pressures, gas types, or control speed and stability requirements, the PID parameters need to be adjusted to achieve the best control effect. Furthermore, when using the PID algorithm for constant pressure control, in addition to focusing on the algorithm itself, attention must also be paid to the hardware configuration and parameter adjustments of the controller to ensure stable system operation.

[0059] This disclosure also provides a constant pressure control method for a pressure vessel, which is applied to the aforementioned constant pressure control system for a pressure vessel. Figure 5 A flowchart illustrating a constant pressure control method according to an embodiment of the present disclosure is shown, as follows: Figure 5 As shown, the method includes the following steps:

[0060] S101. Based on the pressure sensor of the pressure vessel constant pressure control system, the pressure signal of the pressure vessel of the pressure vessel constant pressure control system is acquired in real time.

[0061] S102. The control unit based on the constant pressure control system of the pressure vessel generates a control signal according to the pressure signal, and controls the air intake and exhaust volume of the pressure vessel in real time according to the control signal, so that the pressure of the pressure vessel is maintained at a preset pressure value.

[0062] Furthermore, the control unit based on the constant pressure control system of the pressure vessel generates a control signal according to the pressure signal, including:

[0063] Based on the control terminal in the control unit, the pressure signal and the preset pressure value are input into the proportional-integral-derivative control algorithm, and the proportional-integral-derivative control algorithm is executed to obtain the control signal. The control signal is a current signal, and the range of the control signal is from 4 mA to 20 mA.

[0064] Furthermore, the step of controlling the air intake and exhaust volume of the pressure vessel in real time according to the control signal includes:

[0065] When the control signal is 12 mA, the first proportional valve and the second proportional valve of the actuator in the control unit are closed, and the pressure vessel does not perform air intake and exhaust operations.

[0066] When the control signal increases from 12 mA to 20 mA, the opening of the first proportional valve gradually increases from 0 to 100%, and the pressure vessel performs an air intake operation.

[0067] When the control signal decreases from 12 mA to 4 mA, the opening of the second proportional valve gradually increases from 0 to 100%, and the pressure vessel performs an venting operation.

[0068] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention, such as... Figure 6 As shown, this disclosure also provides an electronic device, which includes a processor and a memory. The memory stores at least one instruction, at least one program, a code set, or an instruction set. The at least one instruction, the at least one program, the code set, or the instruction set is loaded and executed by the processor to implement the constant voltage control method described above.

[0069] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A constant pressure control system for a pressure vessel, characterized by, include: Pressure vessel (1), pressure sensor (2), and control unit (3); The input end of the pressure detection sensor (2) is connected to the pressure vessel (1) to detect the pressure of the pressure vessel (1) and output a pressure signal in real time. The input terminal of the control unit (3) is connected to the output terminal of the pressure detection sensor (2), and the output terminal of the control unit (3) is connected to the pressure vessel (1). The control unit (3) includes a control terminal (31) and an actuator (32). The control terminal (31) and the actuator (32) are electrically connected. The control terminal (31) is used to generate a control signal according to the pressure signal. The actuator (32) is used to control the air intake and exhaust volume in the pressure vessel (1) in real time according to the control signal, so that the pressure of the pressure vessel (1) is maintained at a preset pressure value. The control terminal (31) includes an analog output module; the analog output module includes a signal output channel; the signal output channel is used to output the control signal, the control signal being in the range of 4 mA to 20 mA; The actuator (32) includes a first proportional valve and a second proportional valve, the first proportional valve and the second proportional valve being connected in series; the first proportional valve and the second proportional valve are respectively provided with positive and negative terminals, the positive terminal of the first proportional valve is connected to the negative terminal of the signal output channel, the negative terminal of the first proportional valve is connected to the positive terminal of the second proportional valve, and the negative terminal of the second proportional valve is connected to the positive terminal of the signal output channel; the opening degree of the first proportional valve from 0 to 100% is mapped to the range of 12 mA to 20 mA of the control signal, used to control the air intake of the pressure vessel (1), and the opening degree of the second proportional valve from 0 to 100% is mapped to the range of 12 mA to 4 mA of the control signal, used to control the exhaust volume of the pressure vessel (1).

2. The pressure vessel constant pressure control system of claim 1, wherein, The control terminal (31) includes a programmable logic controller (311), which is used to input the pressure signal and the preset pressure value into the control algorithm, execute the control algorithm, and generate the control signal.

3. The pressure vessel constant pressure control system of claim 2, wherein, The control terminal (31) further includes an analog input module, which is used to convert the pressure signal into a digital signal, and the analog output module is used to convert the control signal into a current signal and output it.

4. The pressure vessel constant pressure control system of claim 3, wherein, The signal output channel is equipped with positive and negative terminals.

5. The pressure vessel constant pressure control system of claim 2, wherein, The control algorithm is a proportional-integral-derivative algorithm, which is used to calculate and generate the control signal based on the difference between the pressure signal and the preset pressure value.

6. A method of constant pressure control of a pressure vessel, characterized by, The method is applied to the constant pressure control system for a pressure vessel according to any one of claims 1 to 5, and the method includes: Based on the pressure sensor of the pressure vessel constant pressure control system, the pressure signal of the pressure vessel of the pressure vessel constant pressure control system is acquired in real time. The control unit of the pressure vessel constant pressure control system generates a control signal based on the pressure signal, and controls the air intake and exhaust volume of the pressure vessel in real time based on the control signal, so that the pressure of the pressure vessel is maintained at a preset pressure value.

7. The pressure vessel constant pressure control method according to claim 6, characterized by, The control unit based on the constant pressure control system of the pressure vessel generates a control signal according to the pressure signal, including: Based on the control terminal in the control unit, the pressure signal and the preset pressure value are input into the proportional-integral-derivative control algorithm, and the proportional-integral-derivative control algorithm is executed to obtain the control signal. The control signal is a current signal, and the range of the control signal is from 4 mA to 20 mA.

8. The pressure vessel constant pressure control method according to claim 6 or 7, characterized by, The step of controlling the air intake and exhaust volume of the pressure vessel in real time according to the control signal includes: When the control signal is 12 mA, the first proportional valve and the second proportional valve of the actuator in the control unit are closed, and the pressure vessel does not perform air intake and exhaust operations. When the control signal increases from 12 mA to 20 mA, the opening of the first proportional valve gradually increases from 0 to 100%, and the pressure vessel performs an air intake operation. When the control signal decreases from 12 mA to 4 mA, the opening of the second proportional valve gradually increases from 0 to 100%, and the pressure vessel performs an venting operation.

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