Differential pressure automatic control under tuyere system and working method

Abstract

The application provides a differential pressure self-control lower air outlet system and a working method, relates to the field of ventilation systems, aims at the problems of response lag of the existing separated differential pressure control architecture, complexity of design, installation and debugging, difficulty of troubleshooting and maintenance, and the problems of measurement accuracy and space occupation contradiction faced by traditional intelligent air valves in terminal application, and integrates a vertical lower air pipe, a rectifying structure, a measurement component, an air volume adjusting mechanism and a control component at a room terminal to form the differential pressure self-control lower air outlet system, the vertical lower air pipe adopts a horizontal-vertical communication layout, the rectifying structure is introduced into the vertical section, the in-situ control component is configured, on-site calculation is performed, and the adjusting valve in the vertical section is driven to execute actions; based on the integration and cooperation of the structural layout and the control logic, the control time lag risk caused by the remote decision and the remote execution is well resolved, and good technical effects of compact structural arrangement, rapid system response and accurate and stable indoor differential pressure maintenance are achieved.

Description

Technical Field

[0001] This invention relates to the field of ventilation systems, specifically to a differential pressure self-controlled downdraft outlet system and its operating method. Background Technology

[0002] In controlled environments such as biosafety laboratories, negative pressure wards, and clean operating rooms, maintaining a stable indoor-outdoor pressure difference is crucial for ensuring safe operation. Currently, mainstream differential pressure control solutions typically employ a separate architecture combining sensors, controllers, and actuators. This involves transmitting indoor differential pressure signals to the building automation system (BAS), which then calculates the signal and sends control signals to variable air volume (VAV) valves installed in the ceiling or ductwork branches to execute the action. However, this remote decision-making and execution model suffers from significant physical and logical lags, with time differences in signal transmission and processing. The lengthy ductwork between the valves and the room's end creates substantial airflow inertia, causing the system to respond sluggishly to transient pressure shocks such as door opening and closing, easily leading to large pressure fluctuations or prolonged oscillations. This makes it difficult to meet the stringent requirements of high-level controlled environments for rapid pressure recovery and stability. Furthermore, current differential pressure control systems often employ a discrete system architecture, with differential pressure sensors, controllers, and dampers typically physically separated and geographically dispersed. This results in delays in signal transmission and control command execution. After a damper activates, the altered airflow must be transmitted through ductwork to affect the room's differential pressure, leading to slow system response, overshoot, or oscillations, making rapid and accurate differential pressure control difficult. These system components require separate design, procurement, and installation of dampers, vents, sensors, and controllers, along with complex piping connections, electrical wiring, and system commissioning. This not only increases initial investment costs but also demands higher levels of expertise from on-site construction and commissioning personnel. If differential pressure control malfunctions, each sensor, controller, actuator, and wiring must be checked individually, making fault location time-consuming, labor-intensive, and maintenance costly. Damperes are usually installed in pipe shafts or ceilings, requiring sufficient installation and maintenance space. In space-constrained or renovation projects, their layout is often limited.

[0003] While existing technologies have developed intelligent variable air volume (VAV) control valves that integrate measurement and actuation, enabling precise measurement and autonomous control of airflow, these products are essentially still duct components. They are not physically and functionally integrated with the room's end air supply and exhaust vents. Their core limitation lies in the physical contradiction between measurement accuracy and space occupancy. To ensure stable airflow and obtain high-precision airflow data, intelligent valves typically require long straight pipe sections, resulting in significant space occupation during indoor installation. If the measurement section is shortened to save space, the measurement accuracy will drop drastically due to insufficient airflow turbulence, leading to failure of indoor differential pressure control. This makes it difficult to meet the requirement of reducing control lag within a compact structure. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a differential pressure self-controlled downdraft outlet system and its operating method. Through local closed-loop control and rectification structure, it effectively reduces signal transmission delay and improves system response speed.

[0005] The first objective of this invention is to provide a differential pressure self-regulating downdraft vent system, comprising:

[0006] The vertical downdraft duct has a connected vertical section and a horizontal section. One end of the horizontal section forms a side air inlet, and the top of the vertical section forms an air outlet that connects to the exhaust duct. The vertical section has a flow straightening structure to straighten the airflow entering through the air inlet. The measurement component, integrated into the vertical downdraft duct, is used to measure real-time airflow. The air volume regulating mechanism, located in the vertical section, includes a regulating valve and an actuator that drives the regulating valve; The control components are installed on the vertical downdraft duct and are electrically connected to the external room differential pressure sensor, measuring components, and actuators, respectively. The controller performs local calculations based on the received real-time differential pressure signal and real-time air volume signal, and drives the actuator to change the opening of the regulating valve to achieve local closed-loop control of indoor differential pressure.

[0007] As a further preferred embodiment, the connection point between the vertical section and the horizontal section is a bend area, and the vertical section is provided with a rectifier channel of equal cross-sectional area. The rectifier channel and the bend area together form a rectifier structure to convert the lateral airflow from the air inlet into vertical laminar flow.

[0008] As a further preferred embodiment, the measuring component is a pitot tube, which is installed at the end of the rectifier structure and inside the rectifier structure, and the regulating valve is installed downstream of the pitot tube.

[0009] As a further preferred embodiment, the control component is also provided with a communication interface for receiving airflow setting instructions from the upper-level control system and is capable of operating independently. The control component can maintain the indoor pressure difference based on the locally stored pressure difference setting value.

[0010] As a further preferred embodiment, the air inlet is detachably equipped with louvers, and a filter is installed in the transverse section.

[0011] The second objective of this invention is to provide a method for operating a differential pressure self-controlled downdraft outlet system, utilizing the differential pressure self-controlled downdraft outlet system of the first objective, comprising: The control components acquire the target differential pressure value in the room through local interaction or communication interfaces; An external room differential pressure sensor continuously measures the real-time differential pressure signal inside the room and transmits it to the control component. At the same time, the measurement component continuously measures the real-time airflow signal passing through the vertical downdraft and transmits it to the control component. The control component calculates the pressure difference deviation between the target differential pressure value and the real-time differential pressure signal in real time, and performs local calculations in conjunction with the current real-time air volume signal to generate the valve opening control signal. The control component sends the damper opening control signal to the controller, which drives the regulating valve to change the opening to adjust the air intake. The change in air intake affects the real-time indoor pressure difference. The system cyclically measures the real-time pressure difference signal and the real-time air volume signal and changes the opening accordingly, forming a local closed-loop control that makes the real-time indoor pressure difference approach and stabilize near the target pressure difference value.

[0012] As a further preferred embodiment, the local calculation employs differential pressure-airflow dual-loop cascade control, including: The outer loop control uses the target differential pressure value as the set reference, combines the real-time differential pressure signal and differential pressure deviation to perform PID calculations, and dynamically outputs the required target air intake volume. The inner loop control uses the target air intake volume as the set benchmark, and compares and calculates the real-time air volume signal obtained by the measurement component to output the air valve opening control signal, thereby reducing the impact of air duct network pressure fluctuations on the actual air intake volume.

[0013] As a further preferred embodiment, a transient impact response mode is also included: During the process of cyclically measuring real-time differential pressure signals and real-time air volume signals and changing the opening degree, when the control component detects that the rate of change of the real-time differential pressure signal exceeds the preset sudden change threshold within a preset time, it is determined that a transient airflow disturbance has occurred. The controller skips local calculations and directly outputs the preset compensation opening command to the actuator to suppress the response to sudden changes in indoor pressure difference; Once the rate of change of the real-time differential pressure signal recovers to a stable threshold, the local calculation is switched back to generate the valve opening control signal.

[0014] As a further preferred embodiment, dynamic resistance compensation logic is also included: During operation, the control component continuously extracts the feedback opening degree of the actuator and compares it with the real-time air volume signal obtained by the measurement component. When the real-time air volume signal shows a downward trend and the duration exceeds the preset judgment period under the same feedback opening degree, the controller determines that the internal resistance of the air outlet system under differential pressure control has increased or the filter has become clogged. Based on this, the controller automatically corrects the reference control parameters of the air valve opening signal to compensate for the air volume and simultaneously triggers the anti-clogging warning signal.

[0015] As a further preferred embodiment, during system operation, the control component uploads real-time differential pressure signals, real-time air volume signals, valve position status of regulating valves, and system alarm status to the upper-level monitoring system via the communication interface, and receives and responds to instructions issued by the upper-level monitoring system in real time without interrupting local closed-loop control.

[0016] Compared with the prior art, the advantages and positive effects of this invention are: To address the issues of lag in existing separate differential pressure control architectures and the trade-off between measurement accuracy and space requirements in traditional intelligent air valves used at the terminal level, a differential pressure self-controlled downdraft system is developed. This system integrates the vertical downdraft duct, rectifier structure, measurement components, airflow regulation mechanism, and control components at the end of the room. As a standalone system product, the vertical downdraft duct adopts a horizontally and vertically connected layout, and a rectifier structure is introduced within the vertical section. This effectively manages the turbulent airflow entering from the side of the air inlet within a compact physical space, transforming it into a stable flow conducive to measurement, thus overcoming the limitations of traditional separate differential pressure control architectures. Traditional airflow measurement methods rely on long straight duct sections. This approach, while ensuring the accuracy of data acquisition by the measurement components, effectively reduces the space occupied by the device. Furthermore, by configuring in-situ control components, the system can directly receive external room pressure differential signals and local real-time airflow signals for edge fusion calculations, and locally drive the regulating valves within the same vertical section. This local closed-loop mode not only effectively reduces communication delays caused by signal transmission to the building automation system but also shortens the physical path of airflow to the room after valve activation, mitigating the lag caused by airflow inertia in long ducts. Based on the integrated coordination of structural layout and control logic, the system effectively mitigates the control lag risks associated with remote decision-making and execution. This allows the system to respond more agilely to transient impacts such as door opening and closing, quickly suppressing drastic changes and long-term oscillations in indoor pressure. This achieves a compact structure, rapid system response, and precise and stable indoor pressure differential.

[0017] The vertical downdraft duct, rectifier structure, measurement components, air volume regulation mechanism and control components are physically and functionally integrated and designed as independent products. This eliminates the need for separate design, data acquisition and installation, facilitating pipeline connection, electrical wiring and system commissioning. It reduces initial investment costs and simplifies on-site construction and debugging. The integrated system components also enable rapid fault location when differential pressure control malfunctions, reducing maintenance costs.

[0018] The control component monitors the rate of change of the real-time differential pressure signal at high frequency. Once it detects an abnormal fluctuation exceeding the sudden change threshold, it immediately identifies it as a transient airflow disturbance. At this time, the system actively skips the time-consuming integration and differentiation process in the conventional local calculation and directly issues a preset compensation opening command to the actuator. This breaks the inherent time lag of traditional feedback control and implements feedforward suppression intervention in the short time after the disturbance occurs. After the airflow subsides, it smoothly switches back to the conventional calculation, which effectively suppresses the drastic change and overshoot of the indoor differential pressure at the moment of door opening and closing, providing a more agile and reliable dynamic anti-interference guarantee for harsh controlled environments.

[0019] By employing dynamic resistance compensation logic, the system gains the ability to autonomously perceive the health status of actuators and the state of physical resistance. Through long-term correlation monitoring and feedback of the mapping relationship between the opening degree and real-time air volume, if it is found that the actual air volume continues to decrease under the same opening degree command, the system determines that the filter is clogged or the physical resistance has increased. Accordingly, the control component adaptively corrects the baseline parameters of the damper opening to supplement the air intake and triggers an early warning simultaneously. This not only enables early self-diagnosis of hidden faults such as filter clogging, but also appropriately extends the effective maintenance-free period of the equipment through algorithmic adaptive compensation, thereby improving the operational stability of the system throughout its entire life cycle.

[0020] By storing the differential pressure setting reference value locally, the control component has the ability to make autonomous decisions while operating offline. At the same time, a parallel processing mechanism is adopted within the control component to ensure that the network interaction process of uploading data to the monitoring system and receiving instructions does not interrupt or preempt the computing resources of the local high-frequency closed-loop control. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a schematic diagram of the differential pressure self-control downdraft outlet system in one or more embodiments of the present invention.

[0023] The components include: 1. Vertical wall; 2. Filter; 3. Louver; 4. Support leg; 5. Air valve; 6. Pitot tube; 7. Flange; 8. Bending area. Detailed Implementation

[0024] Example 1 In a typical embodiment of the present invention, such as Figure 1 As shown, a differential pressure self-control downdraft system is presented.

[0025] Traditional differential pressure control solutions in controlled environments such as biosafety laboratories, negative pressure wards, and clean operating rooms employ a separate architecture combining sensors, controllers, and actuators. This results in time lags in signal transmission and processing, and the long ductwork between the damper 5 and the room's end generates significant airflow inertia. Consequently, the system is slow to respond to transient pressure shocks such as door opening and closing, easily leading to large pressure fluctuations or prolonged oscillations, failing to meet the stringent requirements of rapid pressure recovery in high-level controlled environments. Furthermore, existing intelligent variable air volume (VAV) control dampers integrating measurement and actuation are prone to significant decreases in measurement accuracy due to insufficient airflow turbulence, leading to indoor differential pressure control failure and failing to meet the need for reduced control lag within a compact design.

[0026] In this regard, such as Figure 1 As shown, this embodiment proposes a differential pressure self-control downdraft outlet system, including: The vertical downdraft duct has a connected vertical section and a horizontal section. One end of the horizontal section forms a side air inlet, and the top of the vertical section forms an air outlet that connects to the exhaust duct. The vertical section has a flow straightening structure to straighten the airflow entering through the air inlet. A measuring component, integrated into the vertical downdraft duct, is used to measure real-time airflow. The air volume regulating mechanism, located in the vertical section, includes a regulating valve and an actuator that drives the regulating valve; The control components are installed on the vertical downdraft duct and are electrically connected to the external room differential pressure sensor, measuring components, and actuators, respectively. The controller performs local calculations based on the received real-time differential pressure signal and real-time air volume signal, and drives the actuator to change the opening of the regulating valve to achieve local closed-loop control of indoor differential pressure.

[0027] Specifically, the differential pressure self-control downdraft system is installed and commissioned as an independent product, and its structure and working principle are as follows.

[0028] One end of the horizontal section of the vertical downdraft duct forms a side air inlet to receive airflow from the room. The top of the vertical section forms an air outlet, which connects to an external exhaust duct to discharge airflow. The vertical downdraft duct can be made of galvanized steel, stainless steel, or high-strength plastic to suit different environmental requirements. A vertical wall 1 can be constructed by placing sheet metal or similar materials around the vertical downdraft duct to shield it and isolate it from the outside environment, reducing damage from collisions and scratches to the duct and its components. The connection between the horizontal and vertical sections can be achieved using right-angle bends, beveled connections, or rounded transitions to accommodate varying installation space and airflow resistance requirements. Since the air inlet is positioned at a certain height above the ground, it can be fixed to the vertical wall 1. The horizontal section can be further supported by legs 4 to maintain the position and orientation of the vertical downdraft duct. The air inlet can be an open opening or equipped with grilles, filters, or louvers 3 to prevent large particles from entering.

[0029] Within the vertical section, a flow-rectifying structure is installed to regulate the airflow entering from the inlet. This flow-rectifying structure can consist of a series of parallel guide vanes, a honeycomb structure, or perforated plates. It can also be implemented by configuring the internal channel shape and orientation of the vertical downdraft. When multiple components are used to form the flow-rectifying structure, these components are fixed to the inner wall of the vertical section or supported by brackets. The flow-rectifying structure guides the airflow direction, reduces eddies, and homogenizes the airflow velocity distribution.

[0030] The measurement components can be implemented using various technologies. For example, they could be thermal anemometers that determine wind speed by measuring the cooling effect of airflow on a heating element; ultrasonic anemometers that calculate wind speed by measuring the time difference of sound waves propagating in the airflow; or vortex flow meters that estimate flow rate by detecting the frequency of vortices generated when airflow passes over an obstacle. These measurement components are installed in appropriate locations inside the vertical downdraft duct to ensure accurate capture of airflow information.

[0031] The airflow regulating mechanism includes a regulating valve and an actuator that drives the regulating valve. The regulating valve can be a butterfly valve, gate valve, ball valve, or multi-blade damper, and its opening degree can be adjusted by rotation, translation, or oscillation. The actuator can be an electric actuator, such as a stepper motor or servo motor, which is connected to the regulating valve through a mechanical linkage or gear mechanism, receives electrical signals, and drives the regulating valve to precisely change its opening degree. The regulating valve and actuator are installed in a vertical section, and their positions are selected to effectively control airflow without significantly increasing system resistance.

[0032] The control component is electrically connected to an external room differential pressure sensor, a measuring component, and the actuator of the airflow regulating mechanism. The room differential pressure sensor is installed indoors or between the room and the external environment to continuously monitor changes in the pressure difference between indoors and outdoors, transmitting the real-time differential pressure signal to the control component. The measuring component transmits the real-time airflow signal to the control component. The control component then converts the calculation results into an electrical signal, driving the actuator to change the opening degree of the regulating valve.

[0033] The controller has pre-installed control logic and algorithms, such as proportional-integral (PI) control or embedded control. It continuously acquires real-time room pressure differential and real-time airflow data from the vertical downdraft ducts, and calculates the deviation between the current system and the target state based on this data. Based on this deviation, the controller generates corresponding control commands, which are sent to the actuators via electrical signals, causing the regulating valves to adjust their opening. This adjustment directly affects the airflow through the vertical downdraft ducts, thereby changing the indoor pressure differential. This process is a continuous feedback loop, allowing the indoor pressure differential to be dynamically adjusted and maintained within the preset target range, effectively responding to various disturbances.

[0034] like Figure 1 As shown, the connection between the vertical and horizontal sections is designed as a bend, and a rectifier channel with an equal cross-sectional area is provided on the vertical section. This rectifier channel, together with the bend, forms a rectifier structure to transform the lateral airflow from the air inlet into vertical laminar flow.

[0035] The bend zone is the area where the horizontal and vertical sections of a vertical downdraft connect spatially and undergo a directional change. Airflow entering from the horizontal section needs to be deflected within this area before entering the vertical section. A constant cross-sectional area rectifying channel is a channel with a constant cross-sectional area set within the vertical section. A series of parallel or grid-like guide vanes, honeycomb structures, or perforated plates can also be configured within the rectifying channel. Their main function is to guide and stabilize the airflow, eliminate or reduce eddy components in the airflow, and make the airflow velocity distribution more uniform.

[0036] Alternatively, no structural components can be configured; airflow can be directly rectified using the channel. By maintaining a constant cross-sectional area, additional pressure loss and airflow acceleration / deceleration effects caused by changes in cross-sectional area can be avoided, thus effectively improving airflow quality without significantly increasing system resistance. The rectifying channel does not exist independently but works in conjunction with the bends in the vertical downdraft duct to form a complete rectifying structure. The rectifying channel can be placed adjacent to the bend or partially extended into it, guiding and stabilizing the airflow as it deflects. Lateral airflow refers to the airflow entering from the transverse section inlet and flowing primarily in the horizontal direction. Vertical laminar flow refers to the airflow that, after rectification, flows along the vertical section axis with parallel streamlines and no obvious eddies or turbulent components.

[0037] like Figure 1 As shown, the measuring component is a Pitot tube 6, which is installed at the end of the rectifier structure, and the regulating valve is installed in the rectifier structure downstream of the Pitot tube 6.

[0038] The Pitot tube 6 is based on Bernoulli's equation. It indirectly calculates the wind speed by measuring the difference between the total pressure and static pressure (dynamic pressure) of the fluid, and then calculates the air volume by combining the cross-sectional area of ​​the pipe.

[0039] The Pitot tube 6 is installed at the end of the rectifier structure, which effectively organizes the airflow, resulting in a relatively stable and uniform flow pattern, close to laminar flow. Installing the Pitot tube 6 at this location ensures that the wind speed measured by the Pitot tube 6 is closer to the average wind speed inside the duct, thereby improving the accuracy of airflow measurement. The Pitot tube 6 can be fixed using flange connections, threaded fixing, or welding, etc., to ensure its stability under airflow impact.

[0040] The regulating valve is installed within the rectifier structure downstream of the Pitot tube 6. Installing it within the rectifier structure effectively utilizes its airflow-straightening effect, reducing additional disturbances to the airflow during regulation and ensuring that the regulated airflow has been rectified to a certain extent before reaching the Pitot tube 6. The regulating valve can be a butterfly valve, a multi-leaf regulating valve, or a venturi valve, etc. When using a multi-leaf regulating valve, its blades can be matched to the shape of the rectifier channel to reduce the impact on the rectification effect. The actuator can be installed outside the vertical downdraft duct, driving the opening and closing of the regulating valve via a linkage mechanism.

[0041] The control component is also equipped with a communication interface to receive airflow setting commands from the upper-level control system and can operate independently. The control component can maintain the indoor pressure difference based on the locally stored pressure difference setting value.

[0042] Specifically, the communication interface is the hardware and / or software channel through which control components exchange data with external systems. This interface can be implemented using various standard protocols. For example, it can be an RS-485 interface for serial communication with the upper-level control system via the Modbus RTU protocol; it can be an Ethernet interface for network communication via the Modbus TCP / IP or BACnet / IP protocols; or it can be a CAN bus interface for data transmission in industrial control environments. The communication interface enables the entire differential pressure automatic downdraft system to function as a subunit of a building automation system (BAS) or building management system (BMS), facilitating data uploading and command distribution.

[0043] It should be noted that the control component has a first input interface to receive real-time differential pressure signals from a differential pressure sensor installed indoors, a second input interface to receive real-time airflow signals from a measuring component, and an output interface connected to an actuator to output control valve opening adjustment commands.

[0044] Receiving airflow setting commands from the upper-level control system refers to the control component obtaining operational commands or parameter adjustment requests from the higher-level management system through the communication interface. Commands can be direct airflow setpoints, such as requiring the differential pressure automatic control system to maintain a specific airflow rate; they can also be differential pressure setpoints, requiring the system to adjust the indoor differential pressure to a target value; or even commands to switch operating modes. Upon receiving these commands, the control component dynamically adjusts the current control objectives or operating parameters according to its internal logic to respond to the overall control strategy of the upper-level system.

[0045] Independent operation means that the control component can continue to execute its core local closed-loop control function based on its preset program and locally stored parameters, even without input commands from the upper-level control system or communication interruption. The control component integrates a microprocessor, memory, and control algorithms, giving it autonomous decision-making and execution capabilities. It is completely unaffected by external communication conditions, and this independence ensures that the system can maintain basic indoor differential pressure control even in the face of external communication failures, preventing complete system failure due to communication interruption.

[0046] The control component can maintain indoor differential pressure based on a locally stored differential pressure setpoint. This means that when the control component is not controlled by a higher-level system command or operates independently, it will call upon a pre-set differential pressure target value in its internal non-volatile memory as a control reference. This locally stored differential pressure setpoint can be configured during system installation and commissioning, or modified by maintenance personnel through a local interface under specific circumstances. The control component will use this setpoint as a target, combined with real-time differential pressure and real-time airflow signals, to perform local calculations, driving the actuator to change the opening of the regulating valve, thereby ensuring that the indoor differential pressure remains stable near the preset local target value.

[0047] The control algorithm corresponding to the control component is stored in the control algorithm unit of the control unit. This control algorithm unit is built into the control component's program, and its core is a differential pressure-airflow adaptive PID control algorithm. This algorithm compares the received actual room differential pressure with the user-preset target differential pressure value. Based on the magnitude and trend of the deviation, and combined with the current real-time airflow feedback, it performs high-speed calculations to directly generate the optimal control command for adjusting the opening of control valve 5. This control process is completed locally in a closed loop, without relying on complex calculations and transfers from upper-level systems, thus improving response speed and control accuracy.

[0048] The control unit also includes a human-machine interface, including a local display interface (such as an LCD screen) and parameter setting buttons, which are used to view the status of differential pressure, air volume, valve position and other parameters on site and set target values. It can also display instruction information obtained from communication with the upper-level system.

[0049] The upper-level system can dynamically set underground air volume commands based on the building's overall energy consumption strategy, regional usage, or changes in the external environment, thereby optimizing ventilation and differential pressure control throughout the building and improving energy efficiency. Simultaneously, the control components possess independent operating capabilities and can maintain indoor differential pressure based on locally stored differential pressure setpoints, enhancing system reliability. Even in the event of a communication interruption with the upper-level control system, the differential pressure self-controlled downdraft system can continue to autonomously maintain indoor differential pressure, preventing control failure due to communication malfunctions and ensuring stable differential pressure in critical areas. The combination of centralized management flexibility and local operational reliability allows the differential pressure self-controlled downdraft system to better meet the demands of modern buildings for intelligent, efficient, and highly reliable environmental control.

[0050] The air inlet of the differential pressure self-controlled downdraft system is detachably equipped with louvers 3, and a filter 2 is installed in the horizontal section. The louvers 3 have multiple blades, which can initially guide and disperse the airflow entering the vertical downdraft, while effectively blocking larger particles, insects, or other foreign objects from entering the vertical downdraft, thus protecting subsequent components such as measuring devices, airflow regulation mechanisms, and the filter 2 from damage. The detachable installation can be achieved, but is not limited to, using connection mechanisms such as clips, bolts, magnetic attachments, or sliding rails, allowing the louvers 3 to be easily removed from the air inlet for cleaning, maintenance, or replacement.

[0051] The blades of louver 3 can be designed with a fixed angle to provide stable airflow guidance, or with an adjustable angle to adapt to different airflow requirements or environmental conditions. Meanwhile, filter 2 is used to remove solid particulate impurities from the airflow; its core function is to capture some particulate matter and pollutants in the return air. Filter 2 can be selected in different types according to filtration efficiency and application scenarios. For example, a pre-filter 2 can be used to remove larger particles of dust, hair, and fibers; or a medium-efficiency filter 2 can be used to remove finer particles. Filter 2 is installed in a pre-reserved filter support or filter box inside the transverse section, ensuring that the airflow can completely pass through the filter media. For ease of maintenance and replacement, the filter support or filter box is designed with an easy-to-open and easy-to-close structure.

[0052] Example 2 In another typical embodiment of the present invention, such as Figure 1 As shown, a method for operating a differential pressure self-controlled downdraft vent system is provided. Utilizing the differential pressure self-controlled downdraft vent system as described in Example 1, the method includes the following steps: The control components acquire the target differential pressure value in the room through local interaction or communication interfaces; An external room differential pressure sensor continuously measures the real-time differential pressure signal inside the room and transmits it to the control component. At the same time, the measurement component continuously measures the real-time airflow signal passing through the vertical downdraft and transmits it to the control component. The control component calculates the pressure difference deviation between the target differential pressure value and the real-time differential pressure signal in real time, and performs local calculations in conjunction with the current real-time air volume signal to generate the opening control signal for air valve 5. The control component sends the opening control signal of the air valve 5 to the controller, which drives the regulating valve to change the opening to adjust the air intake. The change in air intake affects the real-time pressure difference in the room. The real-time pressure difference signal and the real-time air volume signal are measured cyclically and the opening is changed to form a local closed-loop control that makes the real-time pressure difference in the room approach and stabilize near the target pressure difference value.

[0053] Combination Figure 1 Indoor differential pressure control typically employs a constant supply and variable exhaust system, which maintains a constant indoor air supply volume and controls the indoor differential pressure by adjusting the intake air volume.

[0054] S1: System initialization and parameter setting. The system is powered on, and the control components perform a self-test. Through the human-machine interface or remote settings, input the target indoor pressure difference value ΔP1 (set value, which can be positive or negative) to the control components, and set the relevant parameters of the control algorithm (such as PID parameters, upper and lower limits of airflow).

[0055] S2: Real-time data acquisition. The indoor differential pressure sensor (P) continuously measures the real-time pressure difference ΔP2 between the indoor area and the reference area and transmits the signal to the first input interface of the control component. Simultaneously, the differential pressure anemometer in the system continuously measures the instantaneous airflow Q and transmits the signal to the second input interface of the control component.

[0056] S3: Intelligent Calculation and Decision Making. The control algorithm unit within the control component calculates the pressure difference deviation e = ΔP1 - ΔP2 in real time. The algorithm combines the historical changes (integral and derivative) of this deviation e with the feedback of the current real-time air volume Q to perform dynamic calculations and output an optimal control signal for the opening of the damper 5.

[0057] S4: Fast and precise execution. The control output interface sends the above control signals to the servo motor driver, which drives the valve blades of the intelligent variable air volume control valve 5 to rotate, changing the opening degree, thereby precisely adjusting the air intake volume.

[0058] S5: Closed-loop feedback and stabilization. Changes in air intake immediately affect the indoor pressure difference ΔP2. The new ΔP2 signal is collected again and enters the S2-S4 cycle, forming a high-speed, continuous local closed-loop control, which quickly stabilizes the indoor pressure difference ΔP2 near the target pressure difference value ΔP1.

[0059] S6: Monitoring and Communication (Parallel Step). Throughout the process, the control components continuously upload data such as differential pressure ΔP2, air volume Q, valve position, and alarm status to the upper-level monitoring system via the industrial communication interface, enabling centralized monitoring and data recording.

[0060] Specifically, the working method of the differential pressure self-control downdraft vent system includes the following steps: First, the control component acquires the target differential pressure value within the room through a local interactive interface or communication interface. The local interactive interface is a touchscreen, button panel, or knob integrated into the differential pressure automatic control vent system, allowing users to directly input or select a preset target differential pressure value. The communication interface can be a standard communication protocol interface such as RS485, BACnet, or Modbus, enabling the control component to exchange data with the building management system (BMS) or a higher-level monitoring system and receive differential pressure setting commands from the higher-level system.

[0061] Subsequently, an external room differential pressure sensor continuously measures the real-time differential pressure signal inside the room and transmits it to the control unit. The differential pressure sensor is installed indoors to sense changes in the pressure difference between the indoor and outdoor areas or adjacent areas. Simultaneously, a measuring component on the vertical downdraft continuously measures the real-time airflow signal passing through the downdraft and also transmits it to the control unit. The measuring component can be a Pitot tube 6, a hot-wire anemometer, or a venturi tube, etc., and its function is to provide accurate airflow data as an important input for control calculations.

[0062] Based on this, the control component calculates the pressure difference deviation between the target pressure difference value and the real-time pressure difference signal in real time. This deviation reflects the difference between the current indoor pressure difference and the expected value. The control component further performs local calculations based on the current real-time airflow signal to generate the valve 5 opening control signal. The local calculation can employ various control algorithms, such as proportional-integral-derivative (PID) control, fuzzy control, or adaptive control, with the aim of intelligently determining the required valve opening adjustment amount based on the pressure difference deviation and airflow information.

[0063] Finally, the control component sends the generated valve 5 opening control signal to the controller, driving the actuator in the airflow regulation mechanism to change the valve opening and adjust the air intake. The change in air intake directly affects the indoor air exhaust rate, which in turn affects the real-time indoor pressure difference. The entire process forms a loop: continuously measuring the real-time pressure difference and real-time airflow signals, and adjusting the valve opening based on the calculation results. Through this continuous feedback and adjustment, the real-time indoor pressure difference can approach and stabilize near the target pressure difference value, thus achieving local closed-loop control.

[0064] Using the above-described operating method, the differential pressure self-control vent system can achieve precise, dynamic, local closed-loop control of indoor differential pressure. The control component continuously acquires the target differential pressure value, real-time differential pressure signal, and real-time airflow signal, and performs real-time calculations based on this data to generate the valve opening control signal. This allows the regulating valve to adjust the airflow in a timely and accurate manner, thereby quickly responding to changes in indoor differential pressure and stabilizing it near the target setpoint.

[0065] In this embodiment, the local calculation employs a differential pressure-airflow dual-loop cascaded control. This control strategy includes outer loop control and inner loop control.

[0066] The outer loop control uses the target differential pressure value as a set reference and performs PID calculations based on the real-time differential pressure signal and differential pressure deviation to dynamically output the required target air intake volume. Specifically, the control component first acquires the target differential pressure value set by the user or the upstream system and continuously receives the real-time differential pressure signal transmitted from the external room differential pressure sensor. The control component compares the target differential pressure value with the real-time differential pressure signal and calculates the differential pressure deviation between the two. Subsequently, the control component processes this differential pressure deviation using a proportional-integral-derivative (PID) algorithm. The PID calculation dynamically calculates a control output based on the magnitude of the current deviation, the cumulative deviation, and the rate of change of the deviation. This output is not a direct valve opening degree, but rather the ideal air intake volume that the system needs to achieve to eliminate the differential pressure deviation, i.e., the target air intake volume. Through PID calculations, the outer loop control can ensure that the indoor differential pressure stably approaches and maintains at the target differential pressure value.

[0067] The inner loop control uses the target air intake volume as the setpoint and compares it with the real-time air volume signal acquired by the measurement component to output the valve 5 opening control signal, reducing the impact of duct network pressure fluctuations on the actual air intake volume. Specifically, the target air intake volume dynamically output by the outer loop control is used as the setpoint for the inner loop control. Simultaneously, the measurement component continuously monitors the actual air volume in the vertical downdraft duct and transmits the real-time air volume signal to the control component. The control component compares the target air intake volume output by the outer loop with the real-time air volume signal acquired by the measurement component and calculates the air volume deviation. Based on this deviation, the control component calculates the precise opening of the regulating valve using an internal algorithm (such as another PID controller or lookup table) and generates the corresponding valve 5 opening control signal. This signal is then sent to the actuator to drive the regulating valve to adjust. Because the inner loop directly monitors and controls the actual air volume, when duct network pressure fluctuations cause the actual air volume to deviate from the target, the inner loop quickly adjusts the regulating valve opening, effectively suppressing the impact of these external disturbances on the air intake volume and ensuring the stability of the air volume output.

[0068] In this embodiment, a transient impact response mode is also proposed. During the process of cyclically measuring the real-time differential pressure signal and the real-time air volume signal and changing the opening degree, when the control component detects that the rate of change of the real-time differential pressure signal exceeds the preset sudden change threshold within a preset time, it is determined that a transient airflow disturbance has occurred; the controller skips local calculation and directly outputs the preset compensation opening degree command to the actuator to achieve response suppression of the transient change in indoor differential pressure; after the rate of change of the real-time differential pressure signal recovers to the stable threshold, it switches back to local calculation to generate the opening degree control signal of the air valve 5.

[0069] Specifically, the transient impact response mode is used to address sudden, short-term airflow disturbances in the indoor environment. It can identify transient disturbances and take rapid, pre-set response measures to avoid the response lag or instability that may occur in conventional closed-loop control when faced with such situations. The control component continuously monitors the real-time differential pressure signal transmitted by the room differential pressure sensor. To determine whether a transient disturbance exists, the control component calculates the rate of change of the real-time differential pressure signal within a very short time interval. For example, the control component can sample the differential pressure value every 0.1 seconds, calculate the difference between the current differential pressure and the differential pressure at the previous sampling point, and then divide it by the sampling time interval to obtain the rate of change of the differential pressure. The "preset time" is configured to a very short period, such as 0.1 seconds, 0.2 seconds, or 0.5 seconds, to ensure that transient changes can be captured in a timely manner. The "preset abrupt change threshold" is an empirical value or a critical value determined through system simulation, such as a change of 5 Pascals or 10 Pascals per second. When the rate of change of the differential pressure exceeds this threshold, it is considered that a significant transient disturbance has occurred. When the rate of change of the real-time differential pressure signal exceeds the preset sudden change threshold within a preset time, the control component will immediately identify the current state as a transient airflow disturbance.

[0070] Upon detecting a transient airflow disturbance, the controller suspends or bypasses conventional, complex local calculations (such as PID control or cascaded control) based on real-time differential pressure deviation and airflow signals. This is because conventional calculations require time for iteration and convergence, and may not provide an optimal response in time under transient disturbances, or even result in unstable calculation results due to rapidly changing inputs. Therefore, upon detecting a transient airflow disturbance, the controller no longer relies on real-time calculation results but immediately sends a pre-stored or preset compensation opening command to the actuator based on the disturbance type. The compensation opening command can be a fixed increment or decrement of the control valve opening, such as immediately increasing the valve opening by 5% or decreasing it by 10%, or directly setting it to a specific opening value that has been verified to quickly stabilize the differential pressure. The purpose of this compensation opening command is to provide preliminary, coarse but effective compensation for transient disturbances as quickly as possible, thereby rapidly suppressing drastic fluctuations in differential pressure. By skipping complex local calculations and directly outputting preset compensation opening commands, the system can respond to sudden changes in indoor pressure difference at the fastest speed, effectively mitigating or preventing further deterioration of the pressure difference, thereby minimizing the impact of transient disturbances on indoor environmental stability.

[0071] The control components continuously monitor the rate of change of the real-time differential pressure signal. When the rate of change of differential pressure falls from above the abrupt change threshold and remains below a preset "stability threshold," it indicates that the transient disturbance has essentially subsided and the system is stabilizing. The "stability threshold" is typically smaller than the "abrupt change threshold," for example, changing by 1 Pascal per second, and is used to confirm that the system has returned to a relatively stable state. Once the system is determined to have stabilized, the controller stops the transient shock response mode and re-enables regular local calculations, continuing precise closed-loop control based on the real-time differential pressure and real-time airflow signals to maintain the indoor differential pressure near the target value.

[0072] During long-term operation, the airflow resistance inside the differential pressure control downdraft system may gradually increase due to dust accumulation, filter blockage, and other reasons. This will cause the actual airflow through the vertical downdraft to gradually decrease under the same regulating valve opening, thereby affecting the accuracy and efficiency of differential pressure control. It may even cause the system to fail to maintain the target differential pressure effectively, and it may not be easily detected and dealt with in time.

[0073] To address this, this embodiment proposes a dynamic resistance compensation logic. Specifically, during system operation, the control component continuously extracts the feedback opening degree of the actuator and compares it with the real-time airflow signal acquired by the measurement component.

[0074] The actuator's feedback opening refers to the actual physical position or angle of the regulating valve, typically monitored in real time by an internal position sensor (e.g., potentiometer, Hall effect sensor, or encoder) and transmitted to the control component as an electrical signal. The control component then compares the current feedback opening with the real-time airflow signal provided by the measurement component based on a preset valve opening and airflow relationship model (e.g., a stored lookup table or empirical curve). When the control component detects a continuous downward trend in the real-time airflow signal at the same feedback opening, and this downward trend lasts for more than a preset judgment period, the controller determines that the internal resistance of the air outlet system under differential pressure control has increased or that filter 2 is clogged. For example, the control component can continuously monitor the average airflow and opening relationship over a period of time (e.g., several hours or days). If it finds that the average airflow is consistently lower than the historical benchmark value at the same opening and exceeds a certain deviation range, a judgment is triggered. Once the judgment is established, the controller will automatically adjust the benchmark control parameters of the valve 5 opening signal accordingly to compensate for the airflow. The controller adjusts its internal control logic, such as increasing the target air intake setpoint or directly increasing the commanded opening of the regulating valve, to overcome the increased resistance and ensure that the actual air intake reaches the value required to maintain the target differential pressure. Simultaneously, the controller triggers an anti-clogging warning signal, which can be configured to illuminate a local indicator light, display a warning message on the operating interface, or be uploaded to the upper-level monitoring system via a communication interface to remind maintenance personnel to promptly check and replace filter 2.

[0075] In addition, during system operation, the control component will upload real-time differential pressure signals, real-time air volume signals, valve position status of regulating valves, and system alarm status to the upper-level monitoring system through the communication interface. Without interrupting local closed-loop control, it will receive and respond to instructions issued by the upper-level monitoring system in real time.

[0076] System alarm status refers to abnormal conditions or states requiring attention identified during the operation of the differential pressure self-control downdraft system based on internal diagnostic logic or preset thresholds. For example, when the dynamic resistance compensation logic detects filter 2 blockage or an abnormal increase in system resistance, a corresponding alarm signal will be generated. These alarm statuses can promptly alert maintenance personnel to potential system problems. The communication interface refers to the hardware and software interface used by the control component to exchange data with external devices or systems. This interface can use various standard protocols, such as Modbus, BACnet, LonWorks, Ethernet / IP, etc., to achieve data transmission via wired or wireless means. Its function is to act as a data bridge between the local control component and the upper-level monitoring system.

[0077] A higher-level monitoring system refers to a system located at a higher level that centrally manages and monitors multiple differential pressure controlled downdraft systems or other HVAC equipment, such as a building management system (BMS) or a central control system. The higher-level monitoring system can receive operational data from various local devices, perform data analysis, trend prediction, fault diagnosis, and issue control commands.

[0078] Even while communicating with or receiving commands from the higher-level monitoring system, the local differential pressure closed-loop control algorithm continues to run to ensure stable indoor differential pressure and prevent local control instability due to communication delays or higher-level system failures. It receives and responds to commands from the higher-level monitoring system in real time, and upon receiving a valid command, adjusts local operating parameters, switches operating modes, or executes specific operations based on the command content. For example, the higher-level system can issue new differential pressure setpoints, airflow setting commands, or forced on / off commands.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A differential pressure self-controlled downdraft vent system, characterized in that, include: The vertical downdraft duct has a connected vertical section and a horizontal section. One end of the horizontal section forms a side air inlet, and the top of the vertical section forms an air outlet that connects to the exhaust duct. The vertical section has a flow straightening structure to straighten the airflow entering through the air inlet. The measurement component, integrated into the vertical downdraft duct, is used to measure real-time airflow. The air volume regulating mechanism, located in the vertical section, includes a regulating valve and an actuator that drives the regulating valve; The control components are installed on the vertical downdraft duct and are electrically connected to the external room differential pressure sensor, measuring components, and actuators, respectively. The controller performs local calculations based on the received real-time differential pressure signal and real-time air volume signal, and drives the actuator to change the opening of the regulating valve to achieve local closed-loop control of indoor differential pressure.

2. The differential pressure self-controlled downdraft outlet system as described in claim 1, characterized in that, The connection point between the vertical and horizontal sections is a bend. The vertical section is provided with a rectifier channel of equal cross-sectional area. The rectifier channel and the bend together form a rectifier structure to convert the lateral airflow from the air inlet into vertical laminar flow.

3. The differential pressure self-controlled downdraft outlet system as described in claim 2, characterized in that, The measuring component is a pitot tube, which is installed inside the rectifier structure, and the regulating valve is installed downstream of the pitot tube.

4. The differential pressure self-controlled downdraft outlet system as described in claim 1, characterized in that, The control component is also equipped with a communication interface for receiving airflow setting instructions from the upper-level control system and can operate independently. The control component can maintain the indoor pressure difference based on the locally stored pressure difference setting value.

5. The differential pressure self-controlled downdraft outlet system as described in claim 1, characterized in that, The air inlet is detachably equipped with louvers, and a filter is installed in the horizontal section.

6. A method for operating a differential pressure self-controlled downdraft vent system, utilizing the differential pressure self-controlled downdraft vent system as described in any one of claims 1-5, characterized in that, include: The control components acquire the target differential pressure value in the room through local interaction or communication interfaces; An external room differential pressure sensor continuously measures the real-time differential pressure signal inside the room and transmits it to the control component. At the same time, the measurement component continuously measures the real-time airflow signal passing through the vertical downdraft and transmits it to the control component. The control component calculates the pressure difference deviation between the target differential pressure value and the real-time differential pressure signal in real time, and performs local calculations in conjunction with the current real-time air volume signal to generate the valve opening control signal. The control component sends the damper opening control signal to the controller, which drives the regulating valve to change the opening to adjust the air intake. The change in air intake affects the real-time indoor pressure difference. The system cyclically measures the real-time pressure difference signal and the real-time air volume signal and changes the opening accordingly, forming a local closed-loop control that makes the real-time indoor pressure difference approach and stabilize near the target pressure difference value.

7. The working method of the differential pressure self-control downdraft outlet system as described in claim 6, characterized in that, The local operation employs a differential pressure-airflow dual-loop cascade control, including: The outer loop control uses the target differential pressure value as the set reference, combines the real-time differential pressure signal and differential pressure deviation to perform PID calculations, and dynamically outputs the required target air intake volume. The inner loop control uses the target air intake volume as the set benchmark, and compares and calculates the real-time air volume signal obtained by the measurement component to output the air valve opening control signal, thereby reducing the impact of air duct network pressure fluctuations on the actual air intake volume.

8. The operating method of the differential pressure self-control downdraft outlet system as described in claim 6, characterized in that, It also includes transient impact response modes: During the process of cyclically measuring real-time differential pressure signals and real-time air volume signals and changing the opening degree, when the control component detects that the rate of change of the real-time differential pressure signal exceeds the preset sudden change threshold within a preset time, it is determined that a transient airflow disturbance has occurred. The controller skips local calculations and directly outputs the preset compensation opening command to the actuator to suppress the response to sudden changes in indoor pressure difference; Once the rate of change of the real-time differential pressure signal recovers to a stable threshold, the local calculation is switched back to generate the valve opening control signal.

9. The working method of the differential pressure self-control downdraft outlet system as described in claim 6, characterized in that, It also includes dynamic resistance compensation logic: During operation, the control component continuously extracts the feedback opening degree of the actuator and compares it with the real-time air volume signal obtained by the measurement component. When the real-time air volume signal shows a downward trend and the duration exceeds the preset judgment period under the same feedback opening degree, the controller determines that the internal resistance of the air outlet system under differential pressure control has increased or the filter has become clogged. Based on this, the controller automatically corrects the reference control parameters of the air valve opening signal to compensate for the air volume and simultaneously triggers the anti-clogging warning signal.

10. The operating method of the differential pressure self-controlled downdraft outlet system as described in claim 9, characterized in that, During system operation, the control component uploads real-time differential pressure signals, real-time air volume signals, valve position status of regulating valves, and system alarm status to the upper-level monitoring system through the communication interface. Without interrupting local closed-loop control, it receives and responds to instructions issued by the upper-level monitoring system in real time.

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