Air duct constant pressure purification adjusting control system and method

Abstract

The present disclosure provides a kind of air duct constant pressure purification regulation control system and method, it is related to fresh air purification machine technical field, including indoor pressure difference sensor, for collecting indoor real-time air pressure difference, and the indoor real-time air pressure difference of acquisition is transmitted to controller;Controller is used to obtain indoor real-time air pressure difference, by comparing with set indoor pressure difference standard value, judge the fan speed needed to be adjusted and the drive voltage needed by indoor air supply fan, control fresh air machine enters working mode, carries out indoor positive pressure mode or negative pressure mode regulation;It also includes indoor air quality collector, for collecting indoor air quality data, and the indoor air quality data of acquisition is transmitted to controller, and controller obtains indoor air quality data and converts into the indoor air supply amount and outdoor exhaust air speed needed, controls fresh air machine work, realizes indoor air purification and keeps indoor positive and negative pressure dynamic balance.

Description

Technical Field

[0001] This disclosure relates to the field of fresh air purifier technology, specifically to a constant pressure purification and regulation control system and method for air ducts. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] Currently, homes and some indoor spaces require positive and negative pressure regulation of fresh air systems. Positive pressure systems are suitable for most home environments, effectively preventing the inflow of external odors or dirty air. Negative pressure systems are suitable for rooms with strong odors or where it is necessary to prevent indoor air leakage, such as bathrooms and game rooms. However, most indoor environments currently require positive and negative pressure regulation. Negative pressure fresh air systems can only exhaust polluted indoor air to the outside and cannot introduce fresh outdoor air into the room. Positive pressure fresh air systems, on the other hand, continuously bring outdoor air into the room, making the intake air volume greater than the exhaust air volume, thus creating a positive pressure state indoors. Therefore, a fresh air system that can achieve dynamic balance regulation of indoor positive and negative pressure is needed.

[0004] Current positive and negative pressure regulation systems use valves to control the airflow at the air outlets and return air vents by adjusting the valve opening degree. The air quality and airflow are adjusted according to the opening degree. However, when the valve is tilted at a certain opening degree, since it is a valve for supplying or discharging air, the valve will generate a certain resistance when the airflow is large. This may even cause the valve to shift slightly, affecting the accuracy of positive and negative pressure regulation. Summary of the Invention

[0005] To address the aforementioned issues, this disclosure proposes a constant pressure purification and regulation control system and method for air ducts. The system establishes a constant pressure purification and regulation control system for air ducts, which adjusts the indoor and outdoor pressure difference by moving valves at different positions and using PID control to achieve dynamic pressure balance between indoor and outdoor environments.

[0006] According to some embodiments, the present disclosure adopts the following technical solutions:

[0007] A constant pressure purification and regulation control system for air ducts includes a fresh air unit, and further includes:

[0008] An indoor differential pressure sensor is installed indoors to collect real-time indoor air pressure differences and transmit the collected real-time indoor air pressure differences to the controller.

[0009] The controller is used to obtain the real-time air pressure difference in the room. By comparing it with the set indoor pressure difference standard value, it determines the fan speed that needs to be adjusted and the drive voltage required by the indoor air supply fan, and controls the fresh air unit to adjust the positive and negative pressure so that the room achieves a dynamic balance of positive and negative pressure.

[0010] It also includes an indoor air quality collector, which is installed indoors to collect indoor air quality data and transmit the collected indoor air quality data to the controller. The controller obtains the indoor air quality data and converts it into the required indoor air supply volume and outdoor exhaust wind speed to control the fresh air unit to achieve indoor air purification. At the same time, it feeds back the real-time indoor pressure difference to the controller to maintain a dynamic balance between positive and negative pressure indoors.

[0011] Furthermore, the interior of the fresh air unit is divided into upper and lower layers. The upper layer includes an indoor return air vent, a first fan, and a first movable gate. The first movable gate has two movable positions, A and B, which are set vertically. The lower layer includes an indoor air supply vent, a second fan, and a second movable gate. The second movable gate has two movable positions, C and D, which are set vertically.

[0012] Furthermore, the indoor return air vent is located at one end of the first fan, and the air outlet of the first fan faces away from the indoor return air vent. The first movable gate is located at the other end of the first fan, and the air outlet of the first fan faces the first movable gate.

[0013] Furthermore, the indoor air outlet is located at one end of the second fan, and the air outlet of the second fan faces the indoor air outlet. The second movable gate is located at the other end of the second fan, and the air outlet of the second fan faces away from the second movable gate.

[0014] Furthermore, outdoor fresh air inlets and indoor air supply outlets are arranged vertically outside the first movable gate end and the second movable gate end, forming two air duct cavities between them.

[0015] Furthermore, when the fresh air system is in positive pressure operating mode:

[0016] When the first movable gate moves to end A, the channel at end B opens. When the second movable gate moves to end D, the channel at end C opens. Fresh air enters from the outdoor fresh air inlet, passes through the channel at end C, enters the fresh air fan, passes through the second fan, and is sent into the indoor air outlet to maintain positive pressure indoors.

[0017] Indoor return air enters the fresh air unit from the indoor return air inlet, undergoes sterilization and purification, passes through the first fan, and is then sent to the indoor air supply outlet through the B-end channel to maintain indoor cleanliness.

[0018] Furthermore, when the fresh air system is in negative pressure operating mode:

[0019] When the first movable gate moves to end B, the passage at end A opens. When the second movable gate moves to end C, the passage at end D opens. The indoor return air enters the fresh air unit from the indoor return air inlet and is then sent to the passage at end A by the first fan. The air then passes through the outdoor fresh air inlet from the passage at end A and is discharged outdoors, maintaining negative pressure indoors.

[0020] Indoor air enters the fresh air unit through the C-end channel from the indoor air supply vent near the movable gate. After purification, it is sent to the indoor air supply vent away from the movable gate by the second fan to maintain indoor cleanliness.

[0021] According to some embodiments, the present disclosure adopts the following technical solutions:

[0022] A control method for a constant pressure purification and regulation control system for air ducts, comprising:

[0023] The indoor pressure difference is set and compared with the real-time indoor actual pressure difference. After incremental PID control calculation, the required fan speed is obtained. The controller controls the fresh air unit to work and controls the fan speed in the fresh air unit. After a delay, the difference is calculated with the set pressure difference to form a closed-loop feedback loop, thereby obtaining the drive voltage required for the indoor air supply fan and driving the fresh air unit to enter the corresponding positive and negative pressure adjustment working mode.

[0024] Furthermore, a standard value for indoor PM2.5 is set and compared with the collected real-time indoor PM2.5 value. When the PM2.5 exceeds a certain value, the indoor PM2.5 value is converted into the required indoor air supply volume. The controller uses the indoor fan air volume as the PID set target value and calculates the required outdoor exhaust air velocity through incremental PID control. After a delay calculation, this parameter will be fed back and affect the value of the indoor differential pressure sensor. If the required indoor air supply volume increases, the outdoor exhaust will increase, and the indoor differential pressure will decrease, thus increasing the indoor air supply volume. Conversely, the outdoor exhaust will decrease, and the indoor air supply will decrease, thereby achieving dynamic pressure balance.

[0025] Furthermore, when the fresh air unit is in positive pressure regulation mode, the first movable gate is moved to end A, opening the channel at end B, and the second movable gate is moved to end D, opening the channel at end C. Fresh air enters from the outdoor fresh air inlet, passes through the channel at end C, enters the fresh air unit, and is then sent into the indoor air outlet by the second fan, maintaining positive pressure indoors. Indoor return air enters the fresh air unit from the indoor return air inlet, undergoes sterilization and purification, passes through the first fan, and is then sent into the indoor air outlet by the channel at end B, maintaining indoor cleanliness.

[0026] When the fresh air unit is in negative pressure regulation mode, the first movable gate is moved to end B, opening the passage at end A. The second movable gate is moved to end C, opening the passage at end D. Indoor return air enters the fresh air unit from the indoor return air inlet and is then sent to the passage at end A by the first fan. From the passage at end A, it passes through the outdoor fresh air inlet and is then discharged outdoors, maintaining indoor negative pressure. Indoor air enters the fresh air unit from the indoor air outlet near the movable gate, passes through the passage at end C, and after purification, is sent to the indoor air outlet away from the movable gate by the second fan, entering the room to maintain indoor cleanliness.

[0027] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0028] The system provided in this disclosure uses an indoor differential pressure sensor and an indoor air quality collector to acquire indoor differential pressure and indoor air quality data, which are then converted into the required indoor air supply volume and outdoor exhaust wind speed to achieve indoor air purification and dynamic balance of indoor positive and negative pressure.

[0029] The fresh air unit is equipped with a movable gate, and the fresh air unit is divided into positive pressure mode and negative pressure mode when it is working. In different modes, the indoor positive pressure, indoor negative pressure and indoor cleanliness are adjusted by moving the first and second movable gates to different positions.

[0030] This invention utilizes a combination of control algorithms and a fresh air system to achieve purification and regulation of positive and negative pressure in indoor spaces. Attached Figure Description

[0031] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0032] Figure 1 This is a control flowchart of an embodiment of the present disclosure;

[0033] Figure 2 This is a schematic diagram of the system structure according to an embodiment of the present disclosure.

[0034] Figure 3 This is a schematic diagram of the system under positive pressure mode according to an embodiment of the present disclosure;

[0035] Figure 4 This is a schematic diagram of the system under negative pressure mode according to an embodiment of the present disclosure;

[0036] Among them, 1. Outdoor fresh air inlet, 2. Indoor air supply outlet, 3. Indoor return air inlet, 4. Indoor air supply outlet, 5. First fan, 6. Second fan, 7. First movable gate, 8. Second movable gate, 9. Indoor differential pressure sensor, 10. Indoor air quality collector, 11. Controller, 12. Outdoor fresh air, 13. Indoor air supply, 14. Indoor return air, 15. Indoor air supply, 16. Outdoor air quality collector. Detailed Implementation

[0037] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0038] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] Example 1

[0041] One embodiment of this disclosure provides a constant pressure purification and regulation control system for air ducts, including a fresh air unit, and further comprising:

[0042] An indoor differential pressure sensor is installed indoors to collect real-time indoor air pressure differences and transmit the collected real-time indoor air pressure differences to the controller.

[0043] The controller is used to obtain the real-time air pressure difference in the room. By comparing it with the set indoor pressure difference standard value, it determines the fan speed that needs to be adjusted and the drive voltage required by the indoor air supply fan, and controls the fresh air unit to adjust the positive and negative pressure so that the room achieves a dynamic balance of positive and negative pressure.

[0044] It also includes an indoor air quality collector, which is installed indoors to collect indoor air quality data and transmit the collected indoor air quality data to the controller. The controller obtains the indoor air quality data and converts it into the required indoor air supply volume and outdoor exhaust wind speed to control the fresh air unit to achieve indoor air purification. At the same time, it feeds back the real-time indoor pressure difference to the controller to maintain a dynamic balance between positive and negative pressure indoors.

[0045] like Figure 2As shown, one end of the fresh air unit is provided with an indoor return air inlet 3 and an indoor supply air inlet 4 arranged vertically, and the other end is provided with an outdoor fresh air inlet 1 and an indoor supply air inlet 2 arranged vertically. The interior of the fresh air unit is divided into upper and lower layers. The upper layer structure includes the indoor return air inlet 3 and a first fan 5. A first movable gate 7 is provided at the end of the upper layer structure near the outdoor fresh air inlet 1. The lower layer structure includes the indoor supply air inlet 4 and a second fan 6. A second movable gate 8 is provided in the lower layer structure. The second movable gate 8 and the first movable gate 7 are located at the same end.

[0046] Among them, outdoor fresh air inlet 1 is connected to outdoor fresh air 12, indoor return air inlet 3 is connected to indoor return air 14, indoor air supply outlet 2 and indoor air supply outlet 4 are connected to indoor air supply 13 and indoor air supply 15 respectively; the first fan and the second fan are used to adjust the ventilation speed.

[0047] The air outlet of the first fan 5 faces one end of the first movable gate 7, which has two movable positions set vertically, namely end A and end B.

[0048] The air outlet of the second fan 6 faces away from the end of the second movable gate. The second movable gate 8 has two movable positions set up vertically, namely end C and end D. When the movable gate is in different positions A, B, C and D respectively, the fresh air fan is in different working modes. The positive and negative pressure in the room is adjusted by using the movable position of the movable gate.

[0049] The upper structure's first movable gate 7 and the lower structure's second movable gate 8 are separated from the outdoor fresh air inlet 1 and indoor air outlet 2 by partitions, creating two equal upper and lower air duct chambers. The ventilation ducts and methods differ depending on the operating mode. The upper air duct chamber is connected to the switching duct of the first movable gate, and the lower air duct chamber is connected to the switching duct of the second movable gate.

[0050] like Figure 3 As shown, when the fresh air unit is in positive pressure mode, the first movable gate 7 is moved to end A, at which time the channel at end B is opened. The second movable gate 8 is moved to end D, at which time the channel at end C is opened. Fresh air enters from the outdoor fresh air inlet 1, passes through the channel at end C, enters the fresh air unit, passes through the second fan 6, and is sent into the indoor air outlet 4 to enter the room, maintaining positive pressure indoors.

[0051] Indoor return air enters the fresh air unit through indoor return air inlet 3, undergoes sterilization and purification, passes through the first fan 5, and is then sent to indoor air outlet 2 through the B-end channel to maintain indoor cleanliness.

[0052] An A&R (Anaerobic and Repulsive) combined electric field is set between the indoor return air vent and the primary fan. This field is divided into an ionization zone and a dust collection zone. The ionization zone continuously generates a high concentration of positive ions. Airborne bacteria are surrounded by these positive ions and rapidly acquire saturation charge. Under the influence of this high-concentration, high-energy positive ion environment, negatively charged bacteria undergo rapid electrolysis, an energy release process. Due to this rapid energy release, the bacterial cell walls are severely damaged. Positive ions contact the bacterial surface, releasing their charge and absorbing the opposite charge, thus adsorbing airborne particles. Sufficient positive ions penetrate the porous cell walls, reaching the cell interior, disrupting the cell electrolytes, damaging the cell membrane, and causing bacterial death. This process kills bacteria and viruses while simultaneously adsorbing airborne particles, achieving air sterilization and purification. The purified air is then sent to the indoor air supply vent through the B-end channel after passing through the primary fan, maintaining indoor cleanliness.

[0053] like Figure 4 As shown, when the fresh air unit is in negative pressure mode, the first movable gate 7 is moved to end B, at which point the channel at end A is opened. The second movable gate 8 is moved to end C, at which point the channel at end D is opened. Indoor return air enters the fresh air unit from the indoor return air inlet 3 and is then sent to the channel at end A by the first fan 5. From the channel at end A, it passes through the outdoor fresh air inlet 1 and is then discharged outdoors, maintaining indoor negative pressure.

[0054] Indoor air enters the fresh air unit through the indoor air outlet 2 near the movable gate, passes through the C-end channel, and after purification, is sent by the second fan 6 to the indoor air outlet 4 far away from the second movable gate to maintain indoor cleanliness.

[0055] Specifically, an A&R (Anaerobic and Repulsive) combined electric field is set between the second movable gate and the second fan. This field is divided into an ionization zone and a dust collection zone. The ionization zone continuously generates a high concentration of positive ions. Airborne bacteria are surrounded by these positive ions and rapidly acquire saturation charge. Under the influence of this high-concentration, high-energy positive ion environment, the negatively charged bacteria undergo rapid electrolysis, an energy release process. Due to this rapid energy release, the bacterial cell walls are severely damaged. Positive ions contact the bacterial surface, releasing their charge and absorbing the opposite charge, thus adsorbing airborne particles. Sufficient positive ions penetrate the porous cell walls, reaching the cell interior, disrupting the cell electrolytes, damaging the cell membrane, and causing bacterial death. This process eliminates bacteria and viruses while simultaneously adsorbing airborne particles, achieving air sterilization and purification.

[0056] In one embodiment, the indoor differential pressure sensor 9 and the indoor air quality collector 10 are connected to the controller 11, which is also connected to the outdoor air quality collector 16. The controller 11 is also connected to the fresh air unit. The outdoor air quality collector is used to collect outdoor air quality (PM2.5) and assess outdoor air quality. The indoor differential pressure sensor collects indoor differential pressure values, and the indoor air quality collector collects air quality data and transmits it to the controller. The controller sets the indoor standard differential pressure and the indoor air quality standard value. The controller compares the collected data with the set standard value to determine whether positive or negative pressure purification adjustment control is needed.

[0057] The machine has two internal fans used to maintain positive or negative pressure, and their activation depends on the indoor pressure. It also collects real-time indoor air quality data to adjust the indoor air cleanliness level.

[0058] Example 2

[0059] One embodiment of this disclosure provides a control method for a constant pressure purification and regulation control system for air ducts, utilizing the system described in Embodiment 1. The system includes a fresh air unit and further comprises:

[0060] An indoor differential pressure sensor is installed indoors to collect real-time indoor air pressure differences and transmit the collected real-time indoor air pressure differences to the controller.

[0061] The controller is used to obtain the real-time air pressure difference in the room. By comparing it with the set standard value of indoor pressure difference, it determines the fan speed that needs to be adjusted and the drive voltage required by the indoor air supply fan, and controls the fresh air fan to enter the working mode to adjust the indoor positive pressure mode or negative pressure mode.

[0062] It also includes an indoor air quality collector, which is installed indoors to collect indoor air quality data and transmit the collected indoor air quality data to the controller. The controller obtains the indoor air quality data and converts it into the required indoor air supply volume and outdoor exhaust air speed, controls the fresh air unit to work, and achieves indoor air purification and maintains a dynamic balance of positive and negative pressure indoors.

[0063] Specifically, the interior of the fresh air unit is divided into upper and lower layers. The upper layer includes an indoor return air vent, a first fan, and a first movable gate. The first movable gate has two moving positions, A and B, which are set vertically. The lower layer includes an indoor air supply vent, a second fan, and a second movable gate. The second movable gate has two moving positions, C and D, which are set vertically.

[0064] The indoor return air vent is located at one end of the first fan, and the air outlet of the first fan faces away from the indoor return air vent. The first movable gate is located at the other end of the first fan, and the air outlet of the first fan faces the first movable gate.

[0065] The indoor air supply outlet is located at one end of the second fan, and the air outlet of the second fan faces the indoor air supply outlet. The second movable gate is located at the other end of the second fan, and the air outlet of the second fan faces away from the second movable gate.

[0066] Furthermore, outdoor fresh air inlets and indoor air supply outlets are arranged vertically outside the first movable gate end and the second movable gate end, forming two air duct cavities between them.

[0067] As one embodiment, the specific steps of a control method for a constant pressure purification and regulation control system for air ducts are as follows:

[0068] Set a standard value for indoor pressure difference, compare it with the real-time actual indoor pressure difference, calculate it using incremental PID control, switch the fan drive, obtain the required fan speed, control the fresh air fan to work, and calculate the difference between the calculated value and the set pressure difference after a delay to form a closed-loop feedback loop, thereby obtaining the drive voltage required for the indoor air supply fan.

[0069] By setting the indoor PM2.5 value, the required indoor air supply volume is converted. If the PM2.5 value exceeds a certain level, the indoor air circulation volume needs to be increased, and vice versa. The indoor fan air volume is used as the target value for the PID control. The required outdoor exhaust air velocity is calculated using the incremental PID control method (proportional-integral-derivative). After a delay calculation, this parameter will be fed back and affect the value of the indoor differential pressure sensor. If the required indoor air supply volume increases, the outdoor exhaust will increase, and the indoor differential pressure will decrease. According to the previous PID control loop, the indoor air supply volume will be increased, and vice versa, the outdoor exhaust will decrease and the indoor air supply will decrease, thereby achieving a dynamic balance between positive and negative pressure.

[0070] The calculation process of incremental PID control:

[0071] Δu[n]=K p {e[n]-e[n-1]}+K i e[n]+K d {e[n]-2e[n-1]+e[n-2]}

[0072] The above is the PID calculation formula, where Kp is the proportional coefficient, Ki is the integral coefficient, and Kd is the derivative coefficient. These three coefficients are obtained after testing and tuning. e[n] is the difference between the current indoor and outdoor pressure difference and the target indoor and outdoor pressure difference, e[n-1] is the difference from the previous time, and e[n-2] is the difference from the time before that. Finally, Δu[n] is the incremental value. If the value is positive, the output voltage of Δu[n] will increase; if it is negative, the output voltage of Δu[n] will decrease.

[0073] The air volume of a fan is directly proportional to its driving voltage. The higher the driving voltage, the faster the fan speed, the larger the air volume, and the greater the pressure difference between indoors and outdoors, and vice versa.

[0074] Furthermore, when the fresh air system is in positive pressure operating mode:

[0075] When the first movable gate moves to end A, the channel at end B opens. When the second movable gate moves to end D, the channel at end C opens. Fresh air enters from the outdoor fresh air inlet, passes through the channel at end C, enters the fresh air fan, passes through the second fan, and is sent into the indoor air outlet to maintain positive pressure indoors.

[0076] Indoor return air enters the fresh air unit from the indoor return air inlet, undergoes sterilization and purification, passes through the first fan, and is then sent to the indoor air supply outlet through the B-end channel to maintain indoor cleanliness.

[0077] Furthermore, when the fresh air system is in negative pressure operating mode:

[0078] When the first movable gate moves to end B, the passage at end A opens. When the second movable gate moves to end C, the passage at end D opens. The indoor return air enters the fresh air unit from the indoor return air inlet and is then sent to the passage at end A by the first fan. The air then passes through the outdoor fresh air inlet from the passage at end A and is discharged outdoors, maintaining negative pressure indoors.

[0079] Indoor air enters the fresh air unit through the C-end channel from the indoor air supply vent near the movable gate. After purification, it is sent to the indoor air supply vent away from the movable gate by the second fan to maintain indoor cleanliness.

[0080] As one example, corresponding ventilation ducts are installed at ends A, B, C, and D so that air can be discharged from different vents in different operating modes.

[0081] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0082] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0083] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A constant pressure purification and regulation control system for air ducts, characterized in that, Including fresh air systems, and also: An indoor differential pressure sensor is installed indoors to collect real-time indoor air pressure differences and transmit the collected real-time indoor air pressure differences to the controller. The controller is used to obtain the real-time air pressure difference in the room. By comparing it with the set indoor pressure difference standard value, it determines the fan speed that needs to be adjusted and the drive voltage required by the indoor air supply fan, and controls the fresh air unit to adjust the positive and negative pressure so that the room achieves a dynamic balance of positive and negative pressure. It also includes an indoor air quality collector, which is installed indoors to collect indoor air quality data and transmit the collected indoor air quality data to the controller. The controller obtains the indoor air quality data and converts it into the required indoor air supply volume and outdoor exhaust wind speed, controls the fresh air unit to work, and achieves indoor air purification. At the same time, it feeds back the real-time indoor pressure difference to the controller to maintain a dynamic balance of positive and negative pressure indoors. The interior of the fresh air unit is divided into upper and lower layers. The upper layer includes an indoor return air vent, a first fan, and a first movable gate. The first movable gate has two movable positions, A and B, which are set vertically. The lower layer includes an indoor air supply vent, a second fan, and a second movable gate. The second movable gate has two movable positions, C and D, which are set vertically. When the fresh air system is in positive pressure operating mode: When the first movable gate moves to end A, the channel at end B opens. When the second movable gate moves to end D, the channel at end C opens. Fresh air enters from the outdoor fresh air inlet, passes through the channel at end C, enters the fresh air fan, passes through the second fan, and is sent into the indoor air outlet to maintain positive pressure indoors. Indoor return air enters the fresh air unit from the indoor return air inlet, undergoes sterilization and purification, passes through the first fan, and is then sent to the indoor air outlet through the B-end channel to maintain indoor cleanliness. When the fresh air system is in negative pressure operating mode: When the first movable gate moves to end B, the passage at end A opens. When the second movable gate moves to end C, the passage at end D opens. The indoor return air enters the fresh air unit from the indoor return air inlet and is then sent to the passage at end A by the first fan. The air then passes through the outdoor fresh air inlet from the passage at end A and is discharged outdoors, maintaining negative pressure indoors. Indoor air enters the fresh air unit through the D-end channel from the indoor air supply vent near the movable gate. After purification, it is sent to the indoor air supply vent away from the movable gate by the second fan to maintain indoor cleanliness.

2. The constant pressure purification and regulation control system for air ducts as described in claim 1, characterized in that, The indoor return air vent is located at one end of the first fan, and the air outlet of the first fan faces away from the indoor return air vent. The first movable gate is located at the other end of the first fan, and the air outlet of the first fan faces the first movable gate.

3. The constant pressure purification and regulation control system for air ducts as described in claim 1, characterized in that, The indoor air supply outlet is located at one end of the second fan, and the air outlet of the second fan faces the indoor air supply outlet. The second movable gate is located at the other end of the second fan, and the air outlet of the second fan faces away from the second movable gate.

4. The constant pressure purification and regulation control system for air ducts as described in claim 1, characterized in that, Outdoor fresh air inlets and indoor air supply outlets are arranged vertically outside the first movable gate end and the second movable gate end, forming two air duct cavities between them.

5. A control method for a constant pressure purification and regulation control system for air ducts according to any one of claims 1-4, characterized in that, The indoor pressure difference is set and compared with the real-time indoor actual pressure difference. After incremental PID control calculation, the required fan speed is obtained. The controller controls the fresh air unit to work and controls the fan speed in the fresh air unit. After a delay, the difference is calculated with the set pressure difference to form a closed-loop feedback loop, thereby obtaining the drive voltage required for the indoor air supply fan and driving the fresh air unit to enter the corresponding positive and negative pressure adjustment working mode.

6. The control method as described in claim 5, characterized in that, include: A standard value for indoor PM2.5 is set and compared with the real-time indoor PM2.5 value. When the PM2.5 exceeds a certain value, the indoor PM2.5 value is converted into the required indoor air supply volume. The controller uses the indoor fan air volume as the PID setpoint target value and calculates the required outdoor exhaust air velocity through incremental PID control. After a delay calculation, the outdoor exhaust air velocity will be fed back and affect the value of the indoor differential pressure sensor. If the required indoor air supply volume increases, the outdoor exhaust will increase, and the indoor differential pressure will decrease, thus increasing the indoor air supply volume. Conversely, the outdoor exhaust will decrease, and the indoor air supply will decrease, thereby achieving dynamic pressure balance.

7. The control method as described in claim 5, characterized in that, When the fresh air unit is in positive pressure regulation mode, the first movable gate is moved to end A, opening the channel at end B. The second movable gate is moved to end D, opening the channel at end C. Fresh air enters from the outdoor fresh air inlet, passes through the channel at end C, enters the fresh air unit, and is then sent into the indoor air outlet by the second fan, maintaining positive pressure indoors. Indoor return air enters the fresh air unit from the indoor return air inlet, undergoes sterilization and purification, passes through the first fan, and is then sent into the indoor air outlet by the channel at end B, maintaining indoor cleanliness. When the fresh air unit is in negative pressure regulation mode, the first movable gate is moved to end B, opening the passage at end A. The second movable gate is moved to end C, opening the passage at end D. Indoor return air enters the fresh air unit from the indoor return air inlet and is then sent to the passage at end A by the first fan. From the passage at end A, it passes through the outdoor fresh air inlet and is then discharged outdoors, maintaining indoor negative pressure. Indoor air enters the fresh air unit from the indoor air outlet near the movable gate, passes through the passage at end D, and after purification, is sent to the indoor air outlet away from the movable gate by the second fan, entering the room and maintaining indoor cleanliness.

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