Spraying system capable of intelligently regulating air balance of entire line

Abstract

Disclosed in the present invention is a spraying system capable of intelligently regulating air balance of the entire line, the system comprising an air supply and exhaust control unit, a multi-dimensional sensor unit and a control unit, wherein the air supply and exhaust control unit comprises a plurality of air supply and exhaust systems, which are respectively applied to a load / unload area, an oven, a manual and automatic dust removal area, a slitting area, a UV curing area and a spray booth, and structurally include a high-pressure fan, a make-up air fan, an ambient air supply box, proportional valves, a circulation fan and an exhaust fan, so as to ensure that an air volume and a pressure difference in each area are controllable; the multi-dimensional sensor unit is used for acquiring data, including the air volume, the pressure difference and the VOC concentration in each area; and the control unit comprises a PLC, a group of frequency converters, and an industrial personal computer, and by means of an air balance control algorithm and a VOC concentration control algorithm, a PID control policy is executed on the basis of sensor data, so as to regulate fan speeds and opening degrees of the proportional valves, thereby achieving air balance of the entire line and the stable control of the VOC concentration in the spray booth. The system integrates a plurality of air supply and exhaust mechanisms and intelligent control algorithms, thereby effectively improving environmental control accuracy and efficiency in a spraying process.

Description

A spraying system capable of intelligently adjusting the air balance of the whole line TECHNICAL FIELD

[0001] The present application relates to the technical field of spraying devices, and particularly relates to a spraying system capable of intelligently adjusting the air balance of the whole line. BACKGROUND

[0002] The existing spraying production line usually relies on multiple air supply and exhaust systems to control the air flow in different areas, including the feeding and discharging area, the oven, the dust removal area, the UV curing area and the spraying room. These air supply and exhaust systems adjust the air volume and pressure difference through devices such as fans and proportional valves to meet the requirements of spraying operations on cleanliness, temperature and air flow stability. At the same time, in order to monitor the environmental parameters, the system is usually equipped with pressure difference sensors, air volume sensors and volatile organic compound (VOC) concentration sensors to provide relevant data to assist adjustment.

[0003] However, in the prior art, due to the lack of intelligent unified control mechanism, the operation of the air supply and exhaust systems in each area is usually independent of each other, and the dynamic changes of air volume and pressure difference cannot be coordinated in real time. In addition, the VOC concentration in the spraying room fluctuates greatly, and the existing manual or single control method is difficult to achieve efficient and stable control, affecting the spraying quality and the safety of the working environment.

[0004] Therefore, it is necessary to develop a spraying system capable of intelligently adjusting the air balance of the whole line. SUMMARY

[0005] The present application provides a spraying system capable of intelligently adjusting the air balance of the whole line to improve the environmental control precision and efficiency of the spraying process.

[0006] The present application provides a spraying system capable of intelligently adjusting the air balance of the whole line, comprising:

[0007] The air supply and exhaust control unit comprises multiple independent air supply and exhaust systems, including an environment air supply and exhaust system, an oven circulating air system, a manual dust removal air supply and exhaust system, an automatic dust removal air supply and exhaust system, a UV curing air supply and exhaust system, and a spray house air balance system; the environment air supply and exhaust system is arranged in the feeding and discharging area and comprises a high-pressure fan, an environment air supply box, and a first proportional valve arranged on the environment air supply box; the oven circulating air system is arranged in the heating chamber and comprises a built-in fan and a second proportional valve arranged on the heating chamber; the manual dust removal air supply and exhaust system comprises a first air supply fan and a first air exhaust fan; the automatic dust removal air supply and exhaust system comprises a second air supply fan and a second air exhaust fan; the UV curing air supply and exhaust system comprises a third air supply fan and a third air exhaust fan; the spray house air balance system comprises a fresh air system, a circulating air system, and an exhaust air fan, wherein the fresh air system comprises a fresh air fan, the circulating air system comprises a circulating air fan, and the circulating air system and the exhaust air fan share an air outlet pipe;

[0008] The multi-dimensional sensor unit comprises a first differential pressure sensor arranged in the feeding and discharging area and used for detecting the pressure difference between the feeding and discharging area and the external environment, a first air volume sensor and a second differential pressure sensor arranged in the heating chamber and used for detecting the air volume of the heating chamber and the pressure difference between the heating chamber and the feeding and discharging area, a second air volume sensor and a third differential pressure sensor arranged in the manual dust removal air supply and exhaust system, a third air volume sensor and a fourth differential pressure sensor arranged in the automatic dust removal air supply and exhaust system, a fourth air volume sensor and a fifth differential pressure sensor arranged in the UV curing air supply and exhaust system, a VOC concentration sensor, a sixth differential pressure sensor, and a fifth air volume sensor arranged in the spray house, and a pressure sensor arranged on the air outlet pipe;

[0009] The control unit comprises a PLC controller, a frequency converter group, and an industrial computer, wherein the PLC controller is electrically connected with the multi-dimensional sensor unit, is used for collecting sensor signals and executing a preset control logic, the frequency converter group is electrically connected with each fan and is used for adjusting the rotating speed of the fan, and the industrial computer is used for executing an air balance control algorithm and a VOC concentration control algorithm, wherein the air balance control algorithm is based on the real-time data of each differential pressure sensor and air volume sensor, adopts a PID control strategy, adjusts the output frequency of the corresponding frequency converter and the opening degree of the proportional valve through the PLC controller, and realizes the pressure balance and the set air volume between the regions; the VOC concentration control algorithm is based on the real-time data of the VOC concentration sensor, combines the pressure sensor data, adjusts the rotating speed of the exhaust air fan, the fresh air fan, and the circulating air fan through the PLC controller, and realizes the stable control of the VOC concentration in the spray house.

[0010] Further, the first proportional valve of the environment air supply and exhaust system is provided with a minimum opening value for maintaining the positive pressure state of the upper and lower material loading area relative to the external environment, and the pressure difference between the upper and lower material loading area and the external environment is detected by the first pressure difference sensor.

[0011] Further, the second proportional valve of the oven circulating air system is provided as a make-up air port for adjusting the pressure difference between the linear oven and the environment of the upper and lower material loading area, and the pressure difference is detected by the second pressure difference sensor.

[0012] Further, the pressure sensor on the air outlet pipe is used to detect the pressure of the common air pipe of the circulating air system and the exhaust air fan, and the detection value of the pressure sensor is used as the basis for adjusting the rotating speed of the circulating air fan.

[0013] Further, the air supply and exhaust of the environment air supply and exhaust system is controlled by the high-pressure fan to form an approximate circulating air system, the first proportional valve on the environment air supply box is provided with a minimum opening value, and the high-pressure fan is provided with an initial frequency value to maintain the positive pressure state of the environment of the upper and lower material loading area relative to the external environment during normal operation, and to ensure that the air exchange frequency of the environment of the upper and lower material loading area is not less than 20 times / hour, and the air speed is between 0.2-0.5 m / s.

[0014] Further, the third pressure difference sensor of the manual dust removal air supply and exhaust system is used to monitor the pressure difference between the manual dust removal station and the upper and lower material loading area, and the frequency of the first exhaust fan is adjusted by the frequency converter of the first exhaust fan to maintain a slight negative pressure state in the manual dust removal station.

[0015] Further, the fifth pressure difference sensor of the UV curing air supply and exhaust system is used to monitor the pressure difference between the UV light curing station and the two side passages, and the frequency of the third exhaust fan is adjusted by the frequency converter of the third exhaust fan to maintain a slight negative pressure state in the UV light curing station to reduce the cold air escaping to the linear oven.

[0016] Further, the control unit is specifically used for:

[0017] The first pressure difference sensor measures the pressure difference P load / unload (t) between the upper and lower material loading area and the external environment; the second pressure difference sensor measures the pressure difference ΔP oven (t) between the heating chamber and the upper and lower material loading area; the sixth pressure difference sensor measures the pressure difference ΔP spraybooth (t) between the spraying room and the external environment; the first air volume sensor measures the air volume Q oven (t) of the heating chamber; and the fifth air volume sensor measures the real-time air volume Q spraybooth (t) of the spraying room.

[0018] The pressure difference deviation is calculated according to the following formula 1: e ΔP,i (t) = wΔP,i • (ΔP set,i - ΔP i (t)), i e {load / unload, oven, spray booth} (1)

[0019] where e ΔP,i (t) represents the pressure differential deviation of zone i at time t; load / unload represents the loading and unloading zone; oven represents the heating chamber; spray booth represents the spray booth; w ΔP,i represents the pressure differential weight factor of zone i; ΔP set,i represents the set pressure differential of zone i; ΔP i (t) is the pressure differential data measured by the pressure differential sensor at time t;

[0020] The air volume deviation e Q,i (t) is calculated according to the following formula 2: Q,i (t) = w set,i • (Q i - Q Q,i (t)), i e {oven, spray booth} (2)

[0021] where e Q,i (t) represents the air volume deviation of zone i at time t; oven represents the heating chamber; spray booth represents the spray booth; w set,i represents the air volume weight factor of zone i; Q i represents the set air volume of zone i; Q p1,load / unload (t) is the air volume data measured by the air volume sensor at time t;

[0022] The first proportional valve opening a1(t) is calculated according to the following formula 3:

[0023] where K i1,load / unload is the integral control gain; K d1,load / unload is the differential control gain; κload / unload is the proportional valve amplitude adjustment parameter; ωload / unload is the proportional valve frequency adjustment parameter; t represents time;

[0024] The frequency f1(t) of the built-in fan of the oven circulating air system is calculated according to the following formula 4:

[0025] where K p2,oven is the proportional control gain; K i2,oven is the integral control gain; K d2,oven is the differential control gain; η ovenThe differential pressure deviation suppression factor for fan frequency regulation; t represents time;

[0026] Based on the calculated first proportional valve opening α1(t) and frequency f1(t), the output frequency of the corresponding frequency converter and the proportional valve opening are adjusted by the PLC controller.

[0027] Furthermore, the control unit is also used for:

[0028] Calculate the opening degree α2(t) of the second proportional valve according to the following formula 5:

[0029] Among them, K p3,oven For proportional control gain; K i3,oven For integral control gain; K d3,oven For differential control gain; κ oven For the proportional valve amplitude adjustment parameter; ω oven This is the frequency adjustment parameter for the proportional valve; t represents time.

[0030] Calculate the frequency f2(t) of the fresh air fan according to the following formula 6:

[0031] Among them, K p4,spraybooth For proportional control gain; K i4,spraybooth For integral control gain; K d4,spraybooth ηspraybooth is the differential control gain; ηpraybooth is the differential pressure deviation suppression factor for fan frequency regulation; t represents time.

[0032] Based on the calculated opening degree α2(t) of the second proportional valve and the frequency f2(t), the output frequency of the corresponding frequency converter and the opening degree of the proportional valve are adjusted by the PLC controller.

[0033] Furthermore, the control unit is specifically used for:

[0034] VOC concentration C in the spray booth is obtained using a VOC concentration sensor. VOC (t); The pressure P inside the air duct of the spray booth is obtained using a pressure sensor. outlet (t);

[0035] The collected data is filtered, and the VOC concentration after filtering is calculated according to formulas 7 and 8 below. and the filtered air outlet pressure

[0036] Where N is the size of the filtering window;

[0037] Calculate the VOC concentration deviation e according to the following formula 9. VOC(t):

[0038] Among them, C VOC,set It is the pre-set target VOC concentration for the spray booth; w VOC It is a weighting factor for VOC concentration control;

[0039] Calculate the pressure deviation e according to the following formula 10. P (t):

[0040] Among them, P outlet,set Target air outlet duct pressure; w P As a pressure control weighting factor;

[0041] Calculate the exhaust fan frequency f according to the following formula 11. exhaust (t):

[0042] Among them, K p5 For proportional control gain; K i5 For integral control gain; K d5 The differential control gain is given by t, where t is the current time. In the definite integral, 0 represents the time when the fan starts working.

[0043] Calculate the fresh air fan frequency f according to the following formula 12. fresh (t):

[0044] Among them, K p6 For proportional control gain; K i6 For integral control gain; K d6 The differential control gain is given by t, where t is the current time. In the definite integral, 0 represents the time when the fan starts working.

[0045] The frequency fcirculation(t) of the circulating fan is calculated according to the following formula 13:

[0046] Among them, K p7 For proportional control gain; K i7 For integral control gain; K d7 γ is the differential control gain; t is the current time; 0 in the definite integral represents the time when the fan starts working; γ is the dynamic adjustment factor; β is the amplification coefficient; λ is the exponential suppression factor.

[0047] Based on the calculated exhaust fan frequency f exhaust (t), Fresh air fan frequency f freshThe PLC controller adjusts the speed of the exhaust fan, fresh air fan, and circulating fan to achieve stable control of VOC concentration in the spray booth.

[0048] This application has the following beneficial technical effects:

[0049] (1) By integrating multi-dimensional sensor units and air balance control algorithms, pressure difference and air volume data of each area are collected in real time. Combined with PID control strategy to adjust fan speed and proportional valve opening, pressure balance and precise control of set air volume in areas such as loading and unloading area, heating chamber, and spray booth can be achieved, improving the stability and uniformity of the spraying process. (2) By real-time data input from VOC concentration sensor and pressure sensor, combined with PLC controller and VOC concentration control algorithm, the speed of exhaust fan, fresh air fan and circulating fan can be dynamically adjusted to ensure that the VOC concentration in the spray booth is maintained within a safe and stable range, effectively improving the safety and environmental protection of the working environment. (3) The intelligent control system dynamically adjusts the operating status of each air supply and exhaust system. By reasonably allocating air volume and adjusting fan speed, energy waste caused by excessive air supply and exhaust is avoided, thereby improving the overall energy efficiency of the spraying system. (4) Through the modular design of the air supply and exhaust control unit, each independent system (such as the environmental air supply and exhaust system, the UV curing air supply and exhaust system, etc.) can work in coordination. Combined with the intelligent control of PLC and industrial computer, the unified management of the air balance of the whole line can be realized, and the operating efficiency and reliability of the entire spraying system can be improved. Attached Figure Description

[0050] Figure 1 is a schematic diagram of a spraying system that can intelligently adjust the air balance of the entire production line according to the first embodiment of this application. Detailed Implementation

[0051] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0052] The first embodiment of this application provides a spraying system capable of intelligently adjusting the airflow balance of the entire production line. Please refer to Figure 1, which is a schematic diagram of the first embodiment of this application. The following detailed description of the spraying system capable of intelligently adjusting the airflow balance of the entire production line, provided by the first embodiment of this application, is based on Figure 1.

[0053] The spraying system, which can intelligently adjust the air balance of the entire production line, includes an air supply and exhaust control unit 101, a multi-dimensional sensor unit 102, and a control unit 103.

[0054] The air supply and exhaust control unit 101 includes multiple independent air supply and exhaust systems, including an environmental air supply and exhaust system, an oven circulation air system, a manual dust removal air supply and exhaust system, an automatic dust removal air supply and exhaust system, a UV curing air supply and exhaust system, and a spray booth air balancing system. The environmental air supply and exhaust system is located in the loading and unloading area and includes a high-pressure fan, an environmental air supply box, and a first proportional valve mounted on the environmental air supply box. The oven circulation air system is located in the heating chamber and includes a built-in fan and a second proportional valve mounted on the heating chamber. The manual dust removal air supply and exhaust system includes a first air supply fan and a first exhaust fan. The automatic dust removal air supply and exhaust system includes a second air supply fan and a second exhaust fan. The UV curing air supply and exhaust system includes a third air supply fan and a third exhaust fan. The spray booth air balancing system includes a fresh air system, a circulation air system, and a waste exhaust fan. The fresh air system includes a fresh air fan, the circulation air system includes a circulation fan, and the circulation air system and the waste exhaust fan share a common exhaust duct.

[0055] As a crucial step in the painting production line, the slitting area employs an independent ventilation system. This area is equipped with dedicated ventilation devices that effectively collect debris and dust generated during the slitting process by precisely controlling airflow direction and speed. The system includes localized air supply units at the slitting stations to ensure a stable airflow field within the cutting area, while dust extraction devices are positioned around the stations to prevent dust dispersion.

[0056] Makeup air fans play a crucial role in balancing airflow throughout the system. They are primarily installed in areas requiring precise pressure control, such as transition zones between spray booths and adjacent areas, and at the inlet and outlet of ovens. Operated via frequency converter control, these fans can precisely adjust the makeup air volume based on real-time feedback from differential pressure sensors, helping to maintain the pressure gradient between different functional zones.

[0057] The air supply and exhaust control unit 101 in the intelligent air balance adjustment spraying system is designed to achieve air balance control of the entire spraying production line. This unit ensures that the environmental parameters at each workstation on the production line are always maintained at an optimal state by rationally arranging multiple independent air supply and exhaust systems, thereby improving spraying quality and reducing energy consumption.

[0058] The air supply and exhaust control unit 101 comprises six interconnected air supply and exhaust systems. The environmental air supply and exhaust system is located in the loading and unloading area, primarily driven by a high-pressure fan to circulate airflow, delivering treated clean air to the work area through an environmental air supply box. A first proportional valve on the environmental air supply box automatically adjusts the make-up air volume according to environmental pressure requirements. By controlling the balance between supply and exhaust air, this system maintains a positive pressure relative to the external environment in the loading and unloading area while ensuring an air exchange rate of no less than 20 times per hour, effectively preventing the intrusion of external pollutants. Supply air is delivered through vents located at the top, with a wind speed precisely adjustable within the range of 0.2-0.5 m / s, while exhaust air is collected through return air columns located at the bottom.

[0059] The oven's circulating air system is installed inside the heating chamber, using a built-in fan to circulate hot air. A second proportional valve at the top of the heating chamber serves as a make-up air inlet, allowing adjustment of the fresh air intake as needed. Through precise control, this system ensures a constant, slightly positive pressure between the oven and the loading / unloading areas, guaranteeing oven temperature stability while preventing excessive heat loss.

[0060] The manual dust removal ventilation system is equipped with a primary supply fan and a primary exhaust fan, which work together to maintain the cleanliness of the workstation. By controlling the balance of supply and exhaust air, the system creates a stable, slightly negative pressure environment between the manual dust removal workstation and the loading / unloading area, effectively preventing dust generated during dust removal operations from spreading to other areas. The system maintains an air exchange rate of over 20 times per hour at the workstation, ensuring a continuously clean working environment.

[0061] The structure of the automatic dust removal ventilation system is similar to that of the manual dust removal system, but it has been optimized for automated operation. The system consists of a second supply fan and a second exhaust fan. By precisely controlling their coordination, the system ensures effective dust removal while maintaining a suitable negative pressure difference between the automatic dust removal station and the side passages to prevent dust pollution.

[0062] The UV curing ventilation system employs a combination of a third supply fan and a third exhaust fan, with a focus on temperature control requirements during the UV curing process. By maintaining a slight negative pressure between the workstation and the side channels, the system effectively reduces the infiltration of cold air into the oven, thereby minimizing oven temperature fluctuations and ensuring stable curing results.

[0063] The air balancing system for the spray booth employs an innovative design that integrates a fresh air system, a recirculating air system, and an exhaust fan. The fresh air system, driven by a fresh air fan, provides fresh air to the spray booth; the recirculating air system, through a recirculating fan, recycles the air within the spray booth. Notably, the recirculating air system and the exhaust fan share a single exhaust duct, a design that saves duct space and facilitates unified exhaust management. The exhaust fan has a minimum operating frequency limit and automatically adjusts its exhaust volume based on changes in VOC concentration, ensuring both air quality within the spray booth and efficient energy utilization.

[0064] The various air supply and exhaust systems are interconnected through a duct system and operate collaboratively under the unified scheduling of the control system. This multi-system collaborative design not only ensures that the independent environmental requirements of each workstation are met, but also achieves airflow balance throughout the entire production line, effectively improving coating quality and reducing energy consumption. The operating parameters of each system can be independently adjusted according to production needs, providing extremely high flexibility and adaptability.

[0065] Furthermore, the first proportional valve of the environmental ventilation system is provided with a minimum opening value to maintain a positive pressure state between the loading / unloading area and the external environment. The pressure difference between the loading / unloading area and the external environment is detected by the first differential pressure sensor.

[0066] This embodiment employs a proportional valve control scheme in the environmental ventilation system. A first proportional valve installed on the environmental ventilation box enables precise adjustment of the environmental pressure in the loading and unloading areas. This proportional valve uses an electrically adjustable valve structure, featuring rapid response and precise positioning, and allows for continuous adjustment of its opening degree.

[0067] The minimum opening value of the first proportional valve is a key parameter for ensuring positive pressure in the loading and unloading areas. This minimum opening value is set based on system engineering experience and actual operational requirements, and is typically within 10% to 15% of the valve's full stroke. This minimum opening ensures sufficient make-up airflow even under low system loads, thereby maintaining a positive pressure state in the loading and unloading areas relative to the external environment. The first proportional valve's drive unit uses a high-precision stepper motor equipped with a self-locking mechanism, allowing the valve to be accurately positioned at any opening degree.

[0068] To accurately monitor the pressure difference between the loading / unloading area and the external environment, a high-precision differential pressure sensor was installed in the loading / unloading area. This sensor employs a capacitive differential pressure detection principle, with one pressure sampling port located in the center of the loading / unloading area and the other extending to the external environment. The pressure status of the area is monitored by measuring the pressure difference between the two points. The differential pressure sensor has a measurement range of -50 Pa to +50 Pa and a measurement accuracy better than ±1%, enabling it to sensitively detect minute pressure changes.

[0069] The differential pressure signal detected by the first differential pressure sensor is transmitted to the PLC controller via a shielded cable. When the detected differential pressure value is lower than the set positive pressure value, the control system will first increase the air volume by adjusting the frequency of the high-pressure blower. If the high-pressure blower frequency has reached its maximum value and the differential pressure is still insufficient, the system will appropriately increase the opening of the first proportional valve to increase the make-up air volume. Conversely, when the detected differential pressure is too large, the system will correspondingly reduce the opening of the proportional valve, but always ensure that the opening is not lower than the preset minimum value.

[0070] This control strategy, based on the minimum opening value and combined with a precise differential pressure detection mechanism, effectively prevents external contaminants from seeping into the loading and unloading areas through gaps, while also avoiding excessive positive pressure that could lead to energy waste. In practical applications, this control scheme demonstrates good stability and reliability, maintaining an ideal pressure balance even under conditions of significant fluctuations in external environmental pressure.

[0071] Furthermore, the second proportional valve of the oven circulating air system is set as a makeup air inlet to adjust the pressure difference between the oven and the loading and unloading area environment. The pressure difference is detected by the second differential pressure sensor.

[0072] In this embodiment, the oven's circulating air system incorporates a second proportional valve at the top of the heating chamber, serving as a makeup air inlet. This design fully considers the temperature field distribution and pressure balance requirements during oven operation. The second proportional valve is made of a high-temperature resistant alloy material, possessing excellent heat resistance and structural stability, enabling long-term reliable operation in the oven's high-temperature environment.

[0073] The second proportional valve's air supply function primarily addresses pressure balance control between the oven and the loading / unloading areas of the production line. Because the oven generates rising hot air during operation, it can easily lead to localized negative pressure. If fresh air isn't supplied promptly, untreated air may be drawn in from the loading / unloading areas, affecting the uniformity of the temperature field within the oven. The second proportional valve effectively suppresses this adverse effect by precisely controlling the air supply volume.

[0074] To achieve precise pressure control, a second differential pressure sensor was installed between the heating chamber and the loading / unloading area. This sensor employs a dual-diaphragm differential pressure structure, featuring high-temperature resistance. One pressure tap is located inside the heating chamber, while the other extends into the loading / unloading area environment. The sensor's signal acquisition circuit utilizes a temperature compensation design to ensure stable measurement accuracy under varying temperature conditions.

[0075] The pressure balance control of the oven's circulating air system employs a closed-loop feedback mechanism. When the second differential pressure sensor detects a deviation of the pressure difference between the oven and the loading / unloading zones from the set value, the control system automatically adjusts the opening of the second proportional valve. If the pressure inside the oven is detected to be lower than the target value, the system will appropriately increase the opening of the second proportional valve to increase the make-up air volume; conversely, if the pressure is too high, the valve opening will be reduced to decrease the make-up air volume. This dynamic adjustment ensures that the oven maintains a stable, slightly positive pressure state at all times.

[0076] The control accuracy of the second proportional valve directly affects the oven's performance. Therefore, the proportional valve is driven by a high-precision stepper motor and equipped with a dedicated valve positioner, achieving an opening adjustment accuracy of 0.1 degrees. The valve body adopts a V-shaped adjustment structure, providing excellent flow characteristics within a small opening range, facilitating precise adjustment of the make-up air volume.

[0077] In practical applications, the second proportional valve works in conjunction with the built-in fan. The built-in fan maintains the circulation of hot air inside the oven, while the second proportional valve balances the pressure by adjusting the make-up air volume. This combination not only ensures the uniformity of the temperature inside the oven but also effectively prevents excessive heat loss. When the production line starts, the system first brings the built-in fan to its preset speed, then gradually adjusts the opening of the second proportional valve until an ideal pressure balance is established. During production, even if the oven load changes, the system can respond quickly, adjusting the make-up air volume in a timely manner to maintain a stable pressure balance.

[0078] Furthermore, the supply and exhaust of the environmental ventilation system are controlled by the high-pressure fan to form a near-circular air system. The first proportional valve on the environmental air supply box is set with a minimum opening value, and the high-pressure fan is set with an initial frequency value to maintain a positive pressure state between the loading and unloading area and the external environment during normal operation. At the same time, it ensures that the air exchange rate in the loading and unloading area is not less than 20 times / hour, and the wind speed is between 0.2 and 0.5 meters / second.

[0079] The environmental ventilation system adopts a near-circular air design, using a single high-pressure fan to simultaneously control both supply and exhaust air, thus simplifying the system structure and unifying control. This high-pressure fan employs a backward centrifugal structure, featuring high efficiency and low noise, with a smooth operating characteristic curve that facilitates precise adjustment.

[0080] The system's air supply section delivers treated air to the top of the loading and unloading area via an environmental air supply box. The air supply box employs a baffle structure design with internal flow guides to ensure uniform airflow distribution throughout the supply area. The air outlets are arranged in a grid pattern, with each grid independently adjustable for easy fine-tuning of the on-site airflow. The first proportional valve on the environmental air supply box is an electric butterfly valve, with its minimum opening typically set at approximately 12% of the valve's full stroke. This value, verified through extensive practical application, represents the optimal setting point, ensuring sufficient make-up air while minimizing energy waste.

[0081] The initial frequency of the high-pressure blower is a crucial parameter for the stable operation of the system. Determining this frequency requires comprehensive consideration of factors such as the volume of the loading and unloading areas, the target air exchange rate, and the required air velocity. Through precise calculations, the system sets the initial operating frequency of the high-pressure blower at 35Hz. This frequency generates sufficient airflow while allowing for upward adjustment to accommodate changes in operating conditions. The blower's frequency conversion control employs vector control, enabling smooth speed regulation and avoiding the impact of frequent start-stop cycles on the equipment.

[0082] To ensure the cleanliness of the loading and unloading area, the system strictly controls the air exchange rate to be no less than 20 times per hour. This indicator is determined by the ratio of the actual air volume to the volume of the loading and unloading area, which is monitored in real time by an air volume sensor. During operation, the system continuously calculates the current air exchange rate. If it detects that the rate is lower than the set value, the controller will automatically increase the fan frequency or adjust the proportional valve opening to increase the air volume.

[0083] Wind speed control is another key parameter. The system monitors the wind speed in the work area in real time using wind speed sensors placed at key locations. The control system adjusts the operating frequency of the high-pressure blower to ensure that the wind speed in the work area is always maintained within the range of 0.2-0.5 m / s. This wind speed range effectively prevents dust accumulation without interfering with the workpiece. The wind speed sensors adopt a thermal design, featuring fast response characteristics, and can promptly detect changes in wind speed.

[0084] The exhaust section of the near-circular air system collects air through a return air column located at the bottom. This return air column employs a multi-point intake design and features a filter at the bottom to effectively block larger particles. The cross-sectional area of ​​the return air duct is carefully designed to minimize exhaust resistance while maintaining appropriate airflow velocity to prevent particle deposition. Because the supply and exhaust air are controlled by the same high-pressure fan, the system exhibits excellent self-balancing characteristics, effectively reducing the impact of external disturbances.

[0085] This design not only enables precise control of the loading and unloading area environment but also significantly reduces energy consumption. In actual operation, the system demonstrates excellent stability and reliability, quickly adjusting operating parameters to maintain all indicators within ideal ranges even when operating conditions change. Furthermore, compared to traditional independent ventilation systems, this near-circulating air scheme offers advantages such as lower investment costs and simpler maintenance, making it an economical and efficient solution.

[0086] The multi-dimensional sensor unit 102 includes a first differential pressure sensor disposed in the loading and unloading area for detecting the pressure difference between the loading and unloading area and the external environment; a first airflow sensor and a second differential pressure sensor disposed in the heating chamber for detecting the airflow of the heating chamber and the pressure difference between it and the loading and unloading area, respectively; a second airflow sensor and a third differential pressure sensor disposed in the manual dust removal ventilation system; a third airflow sensor and a fourth differential pressure sensor disposed in the automatic dust removal ventilation system; a fourth airflow sensor and a fifth differential pressure sensor disposed in the UV curing ventilation system; a VOC concentration sensor, a sixth differential pressure sensor, and a fifth airflow sensor disposed in the spray booth; and a pressure sensor disposed on the air outlet duct.

[0087] The spraying system employs a multi-dimensional sensor unit 102 to achieve real-time monitoring of all key areas of the entire production line. Through a rational layout, this sensor unit constructs a comprehensive data acquisition network, providing a reliable data foundation for the system's intelligent control.

[0088] A high-precision differential pressure sensor is installed in the loading and unloading area to monitor the pressure difference between this area and the external environment in real time. This sensor employs a differential pressure design, with one end connected to a pressure tap in the loading and unloading area and the other end connected to a pressure tap in the external environment, continuously monitoring the pressure difference between the two environments. Based on the real-time feedback of the differential pressure data, the system can promptly adjust the operating frequency of the high-pressure blower and the opening of the first proportional valve to ensure that the loading and unloading area is always maintained at an ideal positive pressure state, effectively preventing the intrusion of external contaminants.

[0089] The heating chamber area is equipped with two sensors with different functions: a first airflow sensor and a second differential pressure sensor. The first airflow sensor, using thermal flow detection technology, is installed on the main air duct of the heating chamber and can accurately measure the airflow volume passing through this area. The second differential pressure sensor is responsible for monitoring the pressure difference between the heating chamber and the loading and unloading areas, providing data support for the pressure balance control of the oven's circulating air system. The combined use of these two sensors ensures that the heating chamber receives sufficient air exchange while maintaining an appropriate pressure gradient with adjacent areas.

[0090] In the manual dust removal ventilation system, the second airflow sensor and the third differential pressure sensor work together. The second airflow sensor is installed on the air supply duct to monitor the airflow entering the dust removal station in real time, ensuring that the station maintains a sufficient number of air changes. The third differential pressure sensor monitors the pressure difference between the manual dust removal station and the loading and unloading area. Its data is directly used to adjust the operating parameters of the first exhaust fan, maintaining the station in a stable slightly negative pressure state to prevent dust diffusion.

[0091] The automatic dust removal ventilation system employs a combination of a third airflow sensor and a fourth differential pressure sensor. The third airflow sensor also utilizes the thermal flow detection principle, and its installation location has been optimized to avoid the influence of dust on the sensor. The fourth differential pressure sensor monitors the pressure difference between the automatic dust removal station and the two side channels; its signal is used to control the operation of the second exhaust fan, ensuring that dust generated during the automatic dust removal process is effectively collected.

[0092] The UV curing ventilation system is equipped with a fourth airflow sensor and a fifth differential pressure sensor, both of which are high-temperature resistant. The fourth airflow sensor monitors the ventilation volume of the UV curing station in real time, while the fifth differential pressure sensor monitors the pressure difference between the station and the two side channels. The data from these two sensors provides a basis for the coordinated control of the third supply fan and the third exhaust fan, ensuring sufficient ventilation and cooling while preventing cold air from interfering with the oven's temperature field.

[0093] Multiple sensors of different types were installed in the spray booth area, forming a comprehensive monitoring network. The VOC concentration sensor uses photoionization detection technology to accurately measure the concentration of volatile organic compounds within the spray booth. A sixth differential pressure sensor monitors the pressure difference between the spray booth and adjacent areas, while a fifth airflow sensor monitors the ventilation volume of the spray booth. These sensors, in conjunction with the pressure sensors installed on the exhaust duct, work together to provide data support for VOC control and pressure balance within the spray booth. The pressure sensors on the exhaust duct pay particular attention to pressure changes in the section of pipe shared by the recirculating air system and the exhaust fan; their data directly affects the speed adjustment of the recirculating fan.

[0094] All sensors feature an industrial-grade design with excellent dust and corrosion resistance, ensuring long-term stable operation in harsh industrial environments. The sensor mounting locations are carefully designed to ensure measurement accuracy while facilitating maintenance and repair. Each sensor is equipped with an independent signal conditioning circuit that converts the analog signal into a standard 4-20mA current signal, which is transmitted to the PLC controller via a shielded cable, effectively avoiding electromagnetic interference in the industrial environment.

[0095] Furthermore, the pressure sensor on the outlet duct is used to detect the pressure of the shared duct between the circulating air system and the exhaust fan, and the detected value of the pressure sensor serves as the basis for adjusting the speed of the circulating fan.

[0096] In this embodiment, a dedicated pressure sensor is installed on the shared outlet duct of the circulating air system and the exhaust fan to achieve accurate monitoring of the pressure inside the duct and intelligent adjustment of the fan speed. This pressure sensor uses a diffused silicon pressure-sensitive element, which features fast response and high-precision measurement, accurately capturing minute changes in pressure within the duct.

[0097] The exhaust duct has a circular cross-section, the diameter of which has been optimized through fluid dynamics calculations to ensure sufficient ventilation while avoiding excessive pressure loss. A dedicated pressure measurement port is provided in the duct wall at the pressure sensor installation location, and a dust filter is installed to ensure measurement accuracy. The pressure measurement port is located in a straight section of the duct where airflow is relatively stable, avoiding areas prone to turbulence such as bends and diameter changes.

[0098] The pressure sensor is mounted on the pressure measurement port using a standard flange connection, ensuring reliable sealing and ease of maintenance. The sensor's measurement range is -1000Pa to 1000Pa, with a measurement accuracy better than 0.5%, meeting the system's pressure monitoring requirements. To avoid the influence of ambient temperature on measurement accuracy, a heat-insulating protective layer is installed on the outside of the sensor, and a temperature compensation mechanism is incorporated into the signal processing circuit.

[0099] Data obtained from pressure sensors is crucial for regulating the speed of the circulating fan. When the pressure in the shared duct is detected to be lower than the set value, it indicates that the system's exhaust volume may be insufficient, and the control system will appropriately increase the speed of the circulating fan. Conversely, if the pressure exceeds the set value, the speed of the circulating fan will be reduced to avoid excessive duct resistance. This pressure feedback-based speed regulation method allows the circulating air system and the exhaust fan to achieve optimal collaborative operation.

[0100] The system employs a progressive PID control algorithm to determine the speed regulation strategy for the circulating fan. The controller first compares the measured pressure value with the set pressure value, and then calculates the appropriate speed regulation amount based on the magnitude and trend of the pressure difference. To avoid damage to the fan from frequent speed adjustments, the control algorithm incorporates appropriate hysteresis intervals and rate-of-change limits, resulting in smoother speed regulation.

[0101] In actual operation, this pressure feedback control method demonstrates excellent adaptability. Even when the workload of the exhaust fan changes, the circulating fan can adjust its speed in a timely manner to maintain stable pressure within the duct. This not only improves the system's operating efficiency but also extends the equipment's service life. Furthermore, by avoiding unnecessary high-speed operation, it also achieves significant energy savings.

[0102] Furthermore, the third differential pressure sensor of the manual dust removal ventilation system is used to monitor the pressure difference between the manual dust removal station and the loading and unloading area. The frequency of the first exhaust fan is adjusted by the frequency converter of the first exhaust fan to maintain a slightly negative pressure state at the manual dust removal station.

[0103] This embodiment incorporates a high-precision third differential pressure sensor in the manual dust removal ventilation system to enable real-time monitoring and precise control of the pressure difference between the manual dust removal station and the loading / unloading area. This differential pressure sensor employs a capacitive pressure sensing element, possessing extremely high sensitivity and accurately detecting minute pressure changes, thus providing reliable data support for the system's pressure balance control.

[0104] The installation locations of the third differential pressure sensor were carefully designed, with pressure taps set at both the manual dust removal station and the loading / unloading area. The pressure tap at the manual dust removal station was installed at the center of the working area, avoiding areas with significant airflow disturbance; the pressure tap at the loading / unloading area was selected at a representative location to ensure that the measured differential pressure data accurately reflects the pressure relationship between the two areas. The pressure tapping pipeline is made of corrosion-resistant stainless steel and is equipped with a dust filter to prevent dust from affecting measurement accuracy.

[0105] The system uses a frequency converter in the first exhaust fan to regulate its speed, thereby achieving precise control of the pressure at the manual dust removal station. The frequency converter employs high-performance vector control technology, enabling smooth adjustment of the fan speed. When the third differential pressure sensor detects a deviation from the set value, the frequency converter automatically adjusts the operating frequency of the first exhaust fan based on the direction and magnitude of the deviation. To ensure control stability, the system incorporates soft start and soft stop functions in the frequency converter's control program to prevent sudden changes from impacting the system.

[0106] The slight negative pressure at the manual dust removal station is achieved by precisely controlling the exhaust volume of the first exhaust fan. The system sets the target negative pressure value within a reasonable range based on the station's dimensions and operational requirements. When insufficient negative pressure is detected, the control system appropriately increases the frequency of the first exhaust fan; conversely, when excessive negative pressure occurs, the fan frequency decreases. This dynamic adjustment ensures that the manual dust removal station maintains an ideal slight negative pressure state, effectively preventing dust from spreading outwards without affecting the operator's normal work.

[0107] In practical applications, the system employs an intelligent strategy for controlling the first-row fan. Firstly, based on the characteristics of manual dust removal operations, the system gradually increases the frequency according to a preset speed-up curve when the fan starts, until it reaches the basic operating frequency. During normal operation, the control system dynamically adjusts the fan frequency based on real-time feedback from the third differential pressure sensor, stabilizing the differential pressure value within the set range. When significant pressure fluctuations occur, the system can respond quickly and adjust the fan speed promptly, ensuring that the pressure at the dust removal station remains within a controllable range.

[0108] To adapt to different operating conditions, the system is equipped with multiple operating modes. In standard operating mode, the system strictly implements the preset differential pressure control strategy; in enhanced dust removal mode, the system appropriately increases the negative pressure value to improve dust removal efficiency; in energy-saving mode, the system optimizes the fan's operating parameters and reduces energy consumption while ensuring basic dust removal performance. This flexible control method allows the system to better meet actual production needs.

[0109] Furthermore, the fifth differential pressure sensor of the UV curing air supply and exhaust system is used to monitor the pressure difference between the UV curing station and the two side channels. The frequency of the third exhaust fan is adjusted by the frequency converter of the third exhaust fan to maintain the UV curing station in a slightly negative pressure state, thereby reducing the escape of cold air into the production line oven.

[0110] In this embodiment, the fifth differential pressure sensor installed in the UV curing ventilation system is designed for high temperature resistance and is specifically used for accurate monitoring of the pressure difference between the UV curing station and the two side channels. This sensor uses a high-precision pressure sensing element with a dual-diaphragm structure, exhibiting excellent temperature compensation performance and maintaining stable measurement accuracy even in the high-temperature environment generated by UV curing.

[0111] The fifth differential pressure sensor features a specially designed installation layout. Multiple pressure taps are located inside the UV curing station, and the pressure signals from these points are integrated using a collector to obtain the average pressure value within the station. Pressure taps are also located on both sides of the channel to measure the reference pressure of the channel. The pressure tapping lines are made of high-temperature resistant Teflon material and have a protective structure to prevent UV radiation from damaging the lines. The pressure measurement system is also equipped with a special gas cooling device to ensure that the temperature of the gas entering the sensor is within its operating range.

[0112] The core control strategy of this system is to dynamically adjust the differential pressure using the frequency converter of the third-row fan. The frequency converter employs advanced vector control technology, enabling precise adjustment of the fan speed. Based on the real-time feedback signal from the fifth differential pressure sensor, the system dynamically calculates the required fan speed and adjusts it via the frequency converter. This control method offers a fast response time, allowing for timely handling of pressure fluctuations during the process.

[0113] To maintain a slightly negative pressure at the UV curing station, a specialized pressure control algorithm was designed. When the pressure difference between the station and the channel deviates from the target value, the control system automatically adjusts the frequency of the third exhaust fan. Increasing the frequency enhances the exhaust effect, generating greater negative pressure; decreasing the frequency weakens the exhaust intensity, reducing the negative pressure value. Through this continuous dynamic adjustment, the UV curing station is ensured to always maintain a suitable slightly negative pressure state.

[0114] The system places special emphasis on preventing cold air from escaping into the production line's oven. Because the UV curing station requires continuous ventilation to remove ozone generated by ultraviolet light, this process can easily lead to the intrusion of surrounding cold air. By maintaining a suitable slight negative pressure, the system can effectively control the airflow direction, preventing cold air from entering the oven area through the workpiece inlet / outlet channels. This design not only protects the oven's temperature field stability but also reduces energy loss.

[0115] In actual operation, the system automatically adjusts control parameters according to different stages of the UV curing process. During the UV lamp start-up phase, the system appropriately increases the exhaust volume to quickly expel the initially generated ozone; during the stable operation phase, it maintains ideal ventilation through precise differential pressure control; and during process switching, the system smoothly adjusts parameters to avoid drastic pressure fluctuations. This intelligent control method ensures both the stability of the UV curing process and the efficient use of energy.

[0116] Through precise differential pressure control and reasonable airflow organization, the UV curing ventilation system successfully solved the temperature field protection problem in the curing process, significantly improved the curing quality of the product, and optimized the energy efficiency of the entire production line.

[0117] The control unit 103 includes a PLC controller, a frequency converter group, and an industrial computer. The PLC controller is electrically connected to the multi-dimensional sensor unit and is used to collect sensor signals and execute preset control logic. The frequency converter group is electrically connected to each fan and is used to adjust the fan speed. The industrial computer is used to execute the air balance control algorithm and the VOC concentration control algorithm. The air balance control algorithm is based on real-time data from each differential pressure sensor and air volume sensor, and adopts a PID control strategy. It adjusts the output frequency and proportional valve opening of the corresponding frequency converter through the PLC controller to achieve pressure balance and set air volume between each area. The VOC concentration control algorithm is based on real-time data from the VOC concentration sensor and combined with pressure sensor data. It coordinates the speed of the exhaust fan, fresh air fan, and circulating fan through the PLC controller to achieve stable control of the VOC concentration in the spray booth.

[0118] The control unit 103 adopts a three-layer architecture design consisting of an industrial computer, a PLC controller, and a frequency converter group, realizing complete closed-loop control from data acquisition and algorithm processing to execution control. Through reasonable hardware configuration and advanced software algorithms, this control unit ensures that the air balance of the entire spraying system is always in an optimal state.

[0119] The industrial PC, serving as the system's host computer, utilizes an industrial-grade design, equipped with a high-performance CPU and large-capacity memory, ensuring high reliability and strong anti-interference capabilities. Installed in a separate control cabinet, it features a dustproof and moisture-proof sealed structure and an industrial-grade cooling system, guaranteeing stable operation in harsh industrial environments. The industrial PC runs airflow balance control and VOC concentration control algorithms, which interact with the PLC controller in real-time via industrial Ethernet.

[0120] The PLC controller adopts a modular design, including a main control module, a multi-channel analog input module, a digital input / output module, and a communication module. The analog input module is responsible for acquiring 4-20mA standard current signals from multi-dimensional sensor units, including differential pressure signals, airflow signals, and VOC concentration signals. These signals are converted into engineering quantities after anti-interference processing and digital filtering for use by the control algorithm. The PLC controller processes this data through preset control logic and generates corresponding control commands.

[0121] The frequency converter group consists of multiple industrial frequency converters, each electrically connected to a specific fan. Each frequency converter is equipped with comprehensive protection functions, including overcurrent protection, overvoltage protection, and phase loss protection. The frequency converters can precisely adjust the fan speed according to control commands from the PLC controller, achieving stepless airflow regulation. The speed range of the frequency converters is 20Hz to 50Hz, meeting the system's airflow regulation requirements.

[0122] The air balance control algorithm in the industrial control computer receives data from various differential pressure sensors and airflow sensors in real time and performs calculations using a PID control strategy. The algorithm first compares the measured values ​​with the setpoints to calculate the deviation. Then, based on the magnitude, trend, and accumulation of the deviation, it uses PID calculations to derive the control input. These control inputs are converted into specific execution instructions by the PLC controller, adjusting the output frequency of the corresponding frequency converter and the opening of the proportional valve, thereby achieving pressure balance and airflow control between different zones.

[0123] The VOC concentration control algorithm primarily targets environmental control in the spray booth area. Based on real-time data from VOC concentration sensors and pressure sensor data from the exhaust duct, the algorithm uses a complex calculation process to determine the optimal speed combination of the exhaust fan, fresh air fan, and recirculation fan. When the VOC concentration exceeds a set threshold, the algorithm prioritizes increasing the exhaust fan speed to enhance ventilation; simultaneously, to maintain the negative pressure in the spray booth, the algorithm adjusts the fresh air fan speed accordingly; and the recirculation fan speed is adjusted based on the pressure conditions in the exhaust duct to ensure airflow balance throughout the system.

[0124] The control unit employs a hierarchical control strategy, enabling intelligent system operation. The industrial computer handles complex algorithm calculations and decisions, the PLC controller executes the specific control logic and acquires data, and the frequency converter group executes the final control actions. This hierarchical design ensures both the real-time performance and reliability of the system, while also achieving intelligent and precise control.

[0125] Upon system startup, the control unit first performs a self-test to confirm that all hardware modules are functioning correctly. Then, data from each sensor is collected and digitally filtered, while the control algorithm begins execution. During system operation, the control unit continuously monitors changes in various parameters and adjusts the control strategy accordingly to ensure the entire spraying system remains in optimal condition. In the event of any abnormalities, the control unit immediately implements appropriate protective measures to ensure system safety.

[0126] Furthermore, the control unit is specifically used for:

[0127] The first differential pressure sensor measures the pressure difference P between the loading / unloading area and the external environment. load / unload (t); The second differential pressure sensor measures the pressure difference ΔP between the heating chamber and the loading / unloading zone. oven (t); The sixth differential pressure sensor measures the pressure difference ΔP between the spray chamber and the external environment. spraybooth (t); The first air volume sensor measures the air volume Q of the heating chamber. oven (t); The fifth air volume sensor measures the real-time air volume Q of the spray chamber. spraybooth (t);

[0128] Calculate the pressure difference deviation using Formula 1 as follows: e ΔP,i (t)=w ΔP,i ·(ΔP set,i -ΔP i (t)),i∈{load / unload,oven,spray booth}(1)

[0129] Among them, e ΔP,i(t) represents the differential pressure deviation in region i at time t; load / unload represents the loading / unloading area; oven represents the heating chamber; spray booth represents the spray booth; region i can be the loading / unloading area, the heating chamber, or the spray booth;

[0130] w ΔP,i The pressure difference weighting factor for region i is calculated based on experimental data or set directly based on expert knowledge; a recommended value is 0.5.

[0131] ΔP set,i The set pressure difference for zone i is a predefined target pressure difference value based on the process requirements and system design goals of each zone, typically derived from empirical data and actual process testing. For example, the load / unload zone needs to maintain a positive pressure relative to the outside environment to prevent contaminants from entering, and its set pressure difference may be between 20 and 50 Pa. The oven typically needs to maintain a slight positive pressure relative to the load / unload zone to ensure stable hot air flow, and its set pressure difference is generally between 10 and 30 Pa. The spray booth, on the other hand, typically maintains a negative pressure relative to the outside environment to prevent volatile organic compound (VOC) leakage, and its set pressure difference is generally between -3 and 0 Pa.

[0132] These set differential pressure values ​​can be confirmed through simulation of the relevant process environment or debugging during actual operation. Changes in external air pressure and limitations in equipment capacity may also affect the adjustment of the set values. The set values ​​can be fine-tuned according to the actual usage scenario and environmental conditions to ensure that the system operation meets the comprehensive requirements of safety, process stability, and energy saving.

[0133] ΔP i (t) represents the differential pressure data measured by the differential pressure sensor in region i at time t;

[0134] Calculate the airflow deviation using Formula 2 as follows: e Q,i (t)=w Q,i ·(Q set,i -Q i (t)),i∈{oven,spray booth} (2)

[0135] Among them, e Q,i (t) represents the airflow deviation in region i at time t; oven represents the heated chamber; spray booth represents the spray booth;

[0136] w Q,i The air volume weighting factor for region i is obtained from experimental data or set directly based on expert knowledge, with a recommended value of 0.8.

[0137] Q set,iThe set airflow for zone i is a target airflow value determined based on the actual needs of each zone and the system design objectives. It is typically determined by a combination of the following factors:

[0138] First, based on the purpose and process requirements of each area, the air volume must be set to meet the ventilation and air exchange needs of each area. For example, the loading and unloading area needs sufficient air volume to maintain positive pressure to prevent external pollutants from entering; the heating chamber needs a constant air volume to ensure the uniform distribution of hot air; and the spray booth needs sufficient air volume to exhaust volatile organic compounds (VOCs) to ensure the safety of the working environment.

[0139] Secondly, the airflow setting also depends on the size of the area. Generally, the larger the area, the higher the required airflow. At the same time, the air exchange rate requirements of different areas will also affect the airflow setting. For example, spray booths typically require a higher air exchange rate to quickly remove harmful gases, while loading and unloading areas may only require a lower air exchange rate to maintain pressure balance.

[0140] In addition, the airflow setting will also take into account industry standards and the actual capacity of the equipment. For example, the airflow of the spray booth needs to meet the VOC emission standards in environmental regulations, while not exceeding the maximum output capacity of the fan, to ensure stable operation of the equipment.

[0141] Taking all the above factors into account, the set airflow is generally determined through experimental data, empirical values, and actual test results. The set airflow Q for the heating chamber... set,oven 4500m can be used 3 / h, the set airflow Q of the spray booth set,spraybooth 24000m can be used 3 / h.

[0142] Q i (t) represents the airflow data measured by the airflow sensor in region i at time t.

[0143] Calculate the opening degree α1(t) of the first proportional valve according to the following formula 3:

[0144] Among them, K p1,load / unload For proportional control gain, a value of 1.0 is recommended; K i1,load / unload For integral control gain, a value of 0.1 is recommended; K d1,load / unload ωload is the differential control gain, recommended value 0.01; κload / unload is the proportional valve amplitude adjustment parameter, recommended value 0.05; ωload / unload is the proportional valve frequency adjustment parameter, recommended value 0.1; t represents time.

[0145] Calculate the frequency f1(t) of the built-in fan in the oven's circulating air system according to the following formula 4:

[0146] Among them, K p2,oven For proportional control gain, a value of 1.1 is recommended; K i2,oven For integral control gain, a value of 0.2 is recommended; K d2,oven For differential control gain, a recommended value is 0.05; η oven The differential pressure deviation suppression factor for fan frequency regulation is 0.01; t represents time.

[0147] Based on the calculated first proportional valve opening α1(t) and frequency f1(t), the output frequency of the corresponding frequency converter and the proportional valve opening are adjusted by the PLC controller.

[0148] Furthermore, the control unit is also used for:

[0149] Calculate the opening degree α2(t) of the second proportional valve according to the following formula 5:

[0150] Among them, K p3,oven For proportional control gain, a value of 2.1 is recommended; K i3,oven For integral control gain, a value of 0.6 is recommended; K d3,oven For differential control gain, a recommended value is 0.01; κ oven For the proportional valve amplitude adjustment parameter, a recommended value is 0.05; ω oven This is the frequency adjustment parameter for the proportional valve; a recommended value is 0.1. t represents time.

[0151] Calculate the frequency f2(t) of the fresh air fan according to the following formula 6:

[0152] Among them, K p4,spraybooth For proportional control gain, a value of 1.5 is recommended; K i4,spraybooth For integral control gain, a value of 0.3 is recommended; K d4,spraybooth ηspraybooth is the differential control gain, recommended value 0.02; ηspraybooth is the differential pressure deviation suppression factor for fan frequency regulation, recommended value 0.01; t represents time.

[0153] Based on the calculated opening degree α2(t) of the second proportional valve and the frequency f2(t), the output frequency of the corresponding frequency converter and the opening degree of the proportional valve are adjusted by the PLC controller.

[0154] Furthermore, the control unit is specifically used for:

[0155] VOC concentration C in the spray booth is obtained using a VOC concentration sensor. VOC (t); The pressure P inside the air duct of the spray booth is obtained using a pressure sensor. outlet (t);

[0156] The collected data is filtered, and the VOC concentration after filtering is calculated according to formulas 7 and 8 below. and the filtered air outlet pressure

[0157] Where N is the size of the filtering window;

[0158] Calculate the VOC concentration deviation e according to the following formula 9. VOC (t):

[0159] Among them, C VOC,set It is the pre-set target VOC concentration for the spray booth; w VOC It is a weighting factor for VOC concentration control;

[0160] Calculate the pressure deviation e according to the following formula 10. P (t):

[0161] Among them, P outlet,set Target air outlet duct pressure; w P As a pressure control weighting factor;

[0162] Calculate the exhaust fan frequency f according to the following formula 11. exhaust (t):

[0163] Among them, K p5 For proportional control gain; K i5 For integral control gain; K d5 The differential control gain is given by t, where t is the current time. In the definite integral, 0 represents the time when the fan starts working.

[0164] Calculate the fresh air fan frequency f according to the following formula 12. fresh (t):

[0165] Among them, K p6 For proportional control gain; K i6 For integral control gain; K d6 The differential control gain is given by t, where t is the current time. In the definite integral, 0 represents the time when the fan starts working.

[0166] The frequency fcirculation(t) of the circulating fan is calculated according to the following formula 13:

[0167] Among them, K p7 For proportional control gain; K i7 For integral control gain; K d7γ is the differential control gain; t is the current time; 0 in the definite integral represents the time when the fan starts working; γ is the dynamic adjustment factor; β is the amplification coefficient; λ is the exponential suppression factor.

[0168] Based on the calculated exhaust fan frequency f exhaust (t), Fresh air fan frequency f fresh The PLC controller adjusts the speed of the exhaust fan, fresh air fan, and circulating fan to achieve stable control of VOC concentration in the spray booth.

[0169] First, the control unit uses a VOC concentration sensor to obtain the real-time VOC concentration C in the spray chamber. VOC (t), and obtain the real-time pressure P in the air outlet duct through a pressure sensor. outlet (t), where t represents the current time. To improve the stability and reliability of the data, the collected data is filtered. The method for calculating the filtered VOC concentration value is as follows: the window size N is usually determined based on the system's real-time performance and anti-interference capability, with a recommended value of 50, depending on the frequency and amplitude of environmental fluctuations.

[0170] Next, the VOC concentration deviation e is calculated based on the filtered data. VOC (t) and pressure deviation e P (t). The VOC concentration deviation is calculated using Equation 9, where the target VOC concentration C VOC,set These are values ​​preset according to process requirements and safety requirements, typically ranging from 0.1 to 1 ppm; the weighting factor w for VOC concentration control VOC This is used to adjust the priority of VOC concentration in control; the recommended value is 0.8.

[0171] The pressure deviation is calculated using formula 10, where the target outlet duct pressure P outlet,set The pressure is set according to the negative pressure requirements of the spray booth, generally ranging from -50 to 0 Pa; the pressure control weighting factor w P The recommended value is 1.5, which is used to ensure that pressure deviation has a moderate impact on the control process.

[0172] Based on the calculated deviation, the control unit calculates the efficiencies of the exhaust fan, fresh air fan, and recirculation fan according to formulas 11, 12, and 13, respectively. The frequency f of the exhaust fan... exhaust (t) directly based on VOC concentration deviation e VOC (t), calculated using a PID control strategy, where the proportional gain K p5 Recommended value: 1.0, Integral gain K i5 The recommended value is 0.2, and the differential gain K is... d5 The recommended value is 0.01.

[0173] The frequency of the fresh air fan f fresh (t) is based on the pressure deviation e P (t), using the same PID control strategy, where the proportional gain K p6 Recommended value: 1.5, Integral gain K i6 The recommended value is 0.3, and the differential gain K is... d6 The recommended value is 0.02.

[0174] The calculation method for the frequency fcirculation(t) of the circulating fan is not only based on the pressure deviation e P The PID control of (t) also incorporates the VOC concentration deviation e VOC The nonlinear dynamic adjustment term and suppression term of (t).

[0175] The recommended value for the dynamic adjustment factor γ is 0.05, and the recommended value for the amplification factor β is 0.1, to enhance the responsiveness of VOC concentration deviation to dynamic adjustment. The recommended value for the exponential suppression factor λ is 0.01, to limit the excessive influence of excessively high VOC concentration deviation on the frequency and ensure the stability of the adjustment process.

[0176] Finally, based on the calculated fan frequency, the control unit adjusts the speeds of the exhaust fan, fresh air fan, and circulating fan via the PLC controller. This dynamic adjustment mechanism ensures that the VOC concentration inside the spray booth is maintained within a safe range, while simultaneously maintaining stable outlet duct pressure, thereby optimizing [the process]. The working environment and system operating efficiency inside the room.

[0177] Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A spray system capable of intelligently adjusting the balance of the straightening air, characterized in that, The application relates to a multi-dimensional environmental control system for a spray room, which comprises the following parts: a supply and exhaust control unit, which comprises multiple independent supply and exhaust systems, wherein the supply and exhaust systems comprise an environment supply and exhaust system, an oven circulating air system, a manual dust removal supply and exhaust system, an automatic dust removal supply and exhaust system, a UV curing supply and exhaust system and a spray room air balance system; the environment supply and exhaust system is arranged in a feeding and discharging area and comprises a high-pressure fan, an environment air supply box and a first proportional valve arranged on the environment air supply box; the oven circulating air system is arranged in a heating chamber and comprises an internal fan and a second proportional valve arranged on the heating chamber; the manual dust removal supply and exhaust system comprises a first air supply fan and a first air exhaust fan; the automatic dust removal supply and exhaust system comprises a second air supply fan and a second air exhaust fan; the UV curing supply and exhaust system comprises a third air supply fan and a third air exhaust fan; the spray room air balance system comprises a fresh air system, a circulating air system and an exhaust air fan, wherein the fresh air system comprises a fresh air fan, the circulating air system comprises a circulating air fan, and the circulating air system and the exhaust air fan share an air outlet pipe; a multi-dimensional sensor unit, which comprises a first pressure difference sensor arranged in the feeding and discharging area and used for detecting the pressure difference between the feeding and discharging area and the external environment, a first air volume sensor and a second pressure difference sensor arranged in the heating chamber and respectively used for detecting the air volume of the heating chamber and the pressure difference between the heating chamber and the feeding and discharging area, a second air volume sensor and a third pressure difference sensor arranged in the manual dust removal supply and exhaust system, a third air volume sensor and a fourth pressure difference sensor arranged in the automatic dust removal supply and exhaust system, a fourth air volume sensor and a fifth pressure difference sensor arranged in the UV curing supply and exhaust system, a VOC concentration sensor, a sixth pressure difference sensor and a fifth air volume sensor arranged in the spray room and a pressure sensor arranged on the air outlet pipe; a control unit, which comprises a PLC controller, a frequency converter group and an industrial computer, wherein the PLC controller is electrically connected with the multi-dimensional sensor unit, is used for collecting sensor signals and executing preset control logic, the frequency converter group is electrically connected with each fan and is used for adjusting the rotating speed of the fan, and the industrial computer is used for executing an air balance control algorithm and a VOC concentration control algorithm, wherein the air balance control algorithm is based on the real-time data of each pressure difference sensor and air volume sensor, adopts a PID control strategy, adjusts the output frequency and the opening degree of the proportional valve of the corresponding frequency converter through the PLC controller, realizes the pressure balance and the set air volume among the regions and the VOC concentration control algorithm is based on the real-time data of the VOC concentration sensor, combines the pressure sensor data, adjusts the rotating speed of the exhaust air fan, the fresh air fan and the circulating air fan through the PLC controller, realizes the stable control of the VOC concentration in the spray room; wherein the control unit is specifically used for: The first differential pressure sensor measures the pressure difference ΔP between the feeding and discharging area and the external environment load / unload (t); the second differential pressure sensor measures the pressure difference ΔP between the heating chamber and the feeding and discharging area oven (t); the sixth differential pressure sensor measures the pressure difference ΔP between the spraying room and the external environment spray booth (t); the first air volume sensor measures the air volume Q of the heating chamber oven (t); the fifth air volume sensor measures the real-time air volume Q of the spraying room spray booth (t); calculating the pressure difference deviation according to formula 1 as follows: e ΔP,i (t) = w ΔP,i · (ΔP set,i - ΔP i (t)), i ∈ {load / unload, oven, spray booth} (1) where e ΔP,i (t) represents the differential pressure deviation of zone i at time t; load / unload represents the loading and unloading zone; oven represents the heating chamber; spray booth represents the spray booth; w ΔP,i represents the differential pressure weight factor of zone i; ΔP set,i represents the set differential pressure of zone i; ΔP i (t) is the differential pressure data measured by the differential pressure sensor at time t; calculating the air volume deviation according to formula 2 as follows: e Q,i (t) = w Q,i · (Q set,i - Q i (t)), i e {oven, spray booth} (2) where e Q,i (t) represents the air volume deviation of zone i at time t; oven represents the heating chamber; spray booth represents the spray house; w Q,i represents the air volume weight factor of zone i; Q set,i represents the set air volume of zone i; Q i (t) is the air volume data measured by the air volume sensor at time t; The first proportional valve opening a1(t) is calculated according to the following Equation 3: Among them, K p1,load / unload For proportional control gain; K i1,load / unload For integral control gain; K d1,load / unload ωload is the differential control gain; κload / unload is the proportional valve amplitude adjustment parameter; ωload / unload is the proportional valve frequency adjustment parameter; t represents time. The frequency f1(t) of the built-in fan of the oven circulating air system is calculated according to the following equation 4: Among them, K p2,oven For proportional control gain; K i2,oven For integral control gain; K d2,oven For differential control gain; η oven The differential pressure deviation suppression factor for fan frequency regulation; t represents time; adjusting the output frequency and the opening degree of the proportional valve of the corresponding frequency converter through the PLC controller according to the calculated first proportional valve opening degree alpha1 (t) and frequency f1 (t); the control unit is also used for: The second proportional valve opening a2(t) is calculated according to the following equation 5: Among them, K p3,oven For proportional control gain; K i3,oven For integral control gain; K d3,oven For differential control gain; κ oven For the proportional valve amplitude adjustment parameter; ω oven This is the frequency adjustment parameter for the proportional valve; t represents time. The frequency f2(t) of the fresh air fan is calculated according to the following equation 6: Among them, K p4,spray booth For proportional control gain; K i4,spray booth For integral control gain; K d4,spray booth ηspray booth represents the differential control gain; ηpray booth represents the differential pressure deviation suppression factor for fan frequency regulation; t represents time. According to the calculated second proportional valve opening degree a2(t) and the frequency f2(t), the output frequency of the corresponding frequency converter and the proportional valve opening degree are adjusted by the PLC controller.

2. The spray system of claim 1, wherein, The first proportional valve of the environmental air supply and exhaust system is provided with a minimum opening degree value for maintaining the positive pressure state of the loading and unloading area relative to the external environment, and the pressure difference between the loading and unloading area and the external environment is detected by the first pressure difference sensor.

3. The spray system of claim 1, wherein, The second proportional valve of the oven circulating air system is provided as a make-up air port for adjusting the pressure difference between the linear oven and the loading and unloading area environment, and the pressure difference is detected by the second pressure difference sensor.

4. The spray system of claim 1, wherein, The pressure sensor on the air outlet pipe is used to detect the pressure of the common air pipe of the circulating air system and the exhaust air fan, and the detection value of the pressure sensor is used as the basis for adjusting the rotating speed of the circulating fan.

5. The spray system of claim 1, wherein, The air supply and exhaust of the environmental air supply and exhaust system is controlled by the high-pressure fan to form an approximately circulating air system, the first proportional valve on the environmental air supply box is provided with a minimum opening degree value, and the high-pressure fan is provided with an initial frequency value to maintain the positive pressure state of the environment of the loading and unloading area relative to the external environment during normal operation, and to ensure that the air exchange frequency of the environment of the loading and unloading area is not less than 20 times / hour, and the air speed is between 0.2-0.5 m / s.

6. The spray system of claim 1, wherein, The third pressure difference sensor of the manual dust removal air supply and exhaust system is used to monitor the pressure difference between the manual dust removal station and the loading and unloading area, and the frequency of the first exhaust fan is adjusted by the frequency converter of the first exhaust fan to maintain a slightly negative pressure state in the manual dust removal station.

7. The spray system of claim 1, wherein, The fifth pressure difference sensor of the UV curing air supply and exhaust system is used to monitor the pressure difference between the UV light curing station and the two side passages, and the frequency of the third exhaust fan is adjusted by the frequency converter of the third exhaust fan to maintain a slightly negative pressure state in the UV light curing station, thereby reducing the cold air escaping to the linear oven.

8. The spray system of claim 1, wherein, The control unit is specifically used for: acquiring the VOC concentration C in the spray booth using a VOC concentration sensor VOC (t); acquiring the pressure P in the air outlet duct of the spray booth using a pressure sensor outlet (t); The collected data is filtered, and the filtered VOC concentration is calculated according to the following Equations 7 and 8 and filtered air outlet pipe pressure Wherein, N is the filter window size; The VOC concentration deviation e is calculated according to the following Equation 9 VOC (t): wherein C VOC,set is a pre-set target VOC concentration of the spray booth; w VOC is a weight factor for VOC concentration control; The pressure deviation e is calculated according to the following equation 10 P (t): Ptarget = Ptarget + w (P - Ptarget) (1) outlet,set Ptarget = Ptarget + w (P - Ptarget) (1) P Ptarget = Ptarget + w (P - Ptarget) (1) The exhaust air fan frequency f is calculated according to the following equation 11 exhaust (t): wherein K p5 is a proportional control gain; K i5 is an integral control gain; K d5 is a derivative control gain; t is the current time; and the constant integral represents the time at which the fan starts operating. The new air fan frequency f is calculated according to the following equation 12 fresh (t): wherein K p6 is a proportional control gain; K i6 is an integral control gain; K d6 is a derivative control gain; t is the current time; and the constant integral represents the time at which the fan starts operating. The circulation fan frequency fcirculation(t) is calculated according to the following equation 13: wherein K p7 is a proportional control gain; K i7 is an integral control gain; K d7 is a derivative control gain; t is the current time; the definite integral represents the time at which the fan starts operating; γ is a dynamic adjustment factor; β is an amplification coefficient; and λ is an exponential damping factor. According to the calculated exhaust fan frequency f exhaust (t), the frequency of the fresh air fan, and the circulation fan frequency fcirculation(t), the rotation speed of the exhaust fan, the fresh air fan, and the circulation fan is adjusted by the PLC controller to realize stable control of the spray room VOC concentration.

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