Ventilation structure with noise reduction function and control method

Abstract

The invention belongs to the technical field of ventilation equipment, and particularly relates to a ventilation structure with a noise reduction function and a control method. The ventilation structure comprises a first pipe body, a fan, a second pipe body, a pipe set, a sealing cover and a noise reduction assembly; the first pipe body, the draught fan, the second pipe body, the pipe set and the sealing cover are sequentially connected, and the sealing cover is arranged outdoors. The noise reduction assembly comprises a first sound receiving device arranged on the sealing cover, a second sound receiving device arranged in the first pipe body and a loudspeaker. A first sound receiving device is arranged to collect outdoor noise signals, a second sound receiving device is arranged to collect indoor residual noise signals, a signal processing unit generates and optimizes reverse sound waves through fast Fourier transform and a least mean square adaptive filtering algorithm, the reverse sound waves are sent out by a loudspeaker, and active counteracting of low-frequency noise is achieved. Meanwhile, the sound absorption assembly is arranged in the first branch pipe in the pipe set, medium-high frequency noise can be effectively absorbed, and active and passive cooperative noise reduction is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ventilation equipment, and particularly relates to a ventilation structure with a noise reduction function and a control method. BACKGROUND

[0002] With the acceleration of urbanization, the requirements of buildings on indoor air quality and sound environment are higher and higher. The existing building ventilation structure usually drives outdoor air into the indoor through a fan to improve the air quality. However, at the same time of introducing the air, outdoor noise will also enter the indoor along with the airflow, especially low-frequency noise such as traffic noise and construction noise which is difficult to be effectively attenuated by traditional passive sound insulation materials.

[0003] In the prior art, the common noise reduction methods mainly include the following: Simply relying on sound-absorbing materials: such as setting sound-absorbing cotton or porous structure in the pipeline to absorb part of the middle and high frequency noise. However, the effect on low-frequency noise is limited, and excessive increase of the sound-absorbing layer will lead to increased wind resistance and reduced ventilation efficiency.

[0004] Single active noise reduction technology: arranging a loudspeaker in the air duct to cancel the noise by emitting reverse sound waves. However, due to the complex and variable frequency of environmental noise, the single active noise reduction system is prone to response lag or incomplete suppression.

[0005] Fan speed regulation: some devices reduce noise transmission by reducing the fan speed, but it will directly affect the air exchange amount, and cannot balance the ventilation efficiency and noise reduction effect.

[0006] Therefore, the prior art still has obvious deficiencies in dealing with “how to ensure ventilation efficiency while achieving efficient noise reduction”, and it is urgent to propose a noise reduction scheme with active and passive cooperation. SUMMARY

[0007] To solve the problems in the background art, the present application provides a ventilation structure with a noise reduction function and a control method.

[0008] To achieve the above purpose, the present application provides the following technical scheme: a ventilation structure with a noise reduction function, comprising a first pipe body, a fan, a second pipe body, a pipe group, a cover and a noise reduction assembly. The first pipe body, the fan, the second pipe body, the pipe group and the cover are connected in sequence, and the cover is arranged outdoors. The noise reduction assembly comprises a first sound recording device arranged on the cover, a second sound recording device arranged in the first pipe body and a loudspeaker.

[0009] Preferably, the first recording device is used to collect outdoor ambient noise signals, the second recording device is used to collect indoor noise signals, and the loudspeaker is used to emit a reverse sound wave with the opposite phase to the noise signal to cancel out low-frequency noise entering the room.

[0010] Preferably, the number of the first radio receivers is four, and the four first radio receivers are arranged in an array on the cover.

[0011] Preferably, the pipe assembly includes a first branch pipe and a second branch pipe; the first branch pipe is provided with a sound-absorbing component inside, and the inner wall of the second branch pipe is smooth.

[0012] Preferably, the axis of the second branch pipe is parallel to the axis of the second pipe body, and the axis of the first branch pipe is at an angle to the axis of the second pipe body.

[0013] Preferably, the sound-absorbing component includes at least two discs, through holes, a filter, an outer ring, and a sound-absorbing felt layer; At least two of the discs are disposed on the inner wall of the first branch pipe, the through holes are formed on the discs, the filter screen is connected to the through holes, the outer ring is connected to the discs, and the outer ring is connected to the sound-absorbing felt layer. The through holes on adjacent disks are staggered.

[0014] Preferably, it also includes a control mechanism, which includes two rotating shafts, a brake pad, a support base, a movable base, a limit plate, an electric push rod, and a rotating shaft, as well as one groove, a crossbeam, and a hydraulic cylinder. The two rotating shafts are rotatably connected to the first branch pipe and the second branch pipe respectively. The brake plate is connected to the rotating shaft. The rotating shaft is connected to the support seat. The support seat is slidably connected to the limiting plate. The limiting plate is connected to the moving seat. The moving seat is rotatably connected to the rotating shaft. The support seat is connected to the electric push rod. The output end of the electric push rod is connected to the moving seat. The groove is machined on the crossbeam. The rotating shaft is slidably connected to the groove. The crossbeam is connected to the output end of the hydraulic cylinder.

[0015] Preferably, it also includes two protective nets, which are respectively connected to the first branch pipe and the second branch pipe.

[0016] The present invention also provides a control method for a ventilation structure with noise reduction function, comprising the following steps: S1 Pattern Recognition and Startup: The signal processing unit automatically identifies the required operating mode based on outdoor noise intensity, indoor residual noise level, air quality parameters, and user preset requirements. When no user command is received or environmental parameters do not reach the threshold, the system enters the default ventilation mode. S2 operating mode settings: Based on the pattern identified in step S1, the system switches its operating mode; S3 Dynamic Adjustment Process: During system operation, the signal processing unit collects noise signals and air quality parameters in real time; Based on fuzzy control algorithms, the actions of electric push rods and hydraulic cylinders are dynamically adjusted to change the opening of the brake pads, enabling automatic switching or fine-tuning between modes to ensure optimal ventilation and noise reduction under different environmental conditions.

[0017] Preferably, step S2 further includes: S2.1 Default ventilation mode: The two dampers are perpendicular to each other, and both the first and second branch pipes are partially open to ensure basic ventilation and maintain indoor air circulation; S2.2 Low Noise Priority Mode: The damper of the first branch pipe is kept at a large opening, while the damper of the second branch pipe is reduced, so that air mainly enters through the first branch pipe equipped with sound-absorbing components, enhancing the passive noise reduction effect, and reducing indoor noise in conjunction with the active noise reduction algorithm. S2.3 Air exchange priority mode: The damper of the second branch pipe is kept at a large opening, while the damper of the first branch pipe is partially closed, so that air mainly enters through the second branch pipe with less resistance, thereby improving ventilation efficiency. It is suitable for scenarios with poor air quality or those that require rapid air replacement. S2.4 Directional noise reduction mode: By adjusting the position of the rotating shaft in the tank, the two brake plates produce different opening and closing angles, thereby adjusting the mixed air intake ratio of the first branch pipe and the second branch pipe, balancing noise reduction and air circulation while ensuring ventilation volume. S2.5 Fully Closed / Single Pipe Mode: When the ambient noise is too high or special operating conditions are required, the damper of one branch pipe is completely closed, while the other branch pipe is kept open for air intake to meet specific noise reduction or ventilation needs.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: By setting up a first receiving device to collect outdoor noise signals and a second receiving device to collect indoor residual noise signals, the signal processing unit uses a Fast Fourier Transform (FFT) and Least Mean Square (LMS) adaptive filtering algorithm to generate and optimize reverse sound waves, which are emitted by a loudspeaker, thus achieving active cancellation of low-frequency noise. Simultaneously, a sound-absorbing component is installed inside the first branch pipe of the pipe assembly, which can effectively absorb mid-to-high frequency noise, achieving coordinated active and passive noise reduction. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is an exploded view of the invention; Figure 3 This is a schematic diagram of the connection structure of the control mechanism in this invention; Figure 4 This is a schematic diagram of a partial connection structure of the control mechanism in this invention; Figure 5 This is a schematic diagram of the connection structure between the capping and noise reduction components in this invention; Figure 6 This is a schematic diagram of the planar connection structure of the noise reduction component in this invention; Figure 7 This is a schematic diagram of the connection structure of the sound-absorbing component in this invention; Figure 8 This is a schematic diagram of the connection structure of the sound-absorbing component in this invention from another perspective.

[0020] Explanation of reference numerals in the attached figures: 1-First pipe body, 10-Protective net, 2-Fan, 3-Second pipe body, 4-First branch pipe, 5-Second branch pipe, 6-Control mechanism, 601-Electric push rod, 602-Moving seat, 603-Rotating shaft, 604-Crossbeam, 605-Trench, 606-Support seat, 607-Limit plate, 608-Brake plate, 609-Rotating shaft, 610-Hydraulic cylinder, 7-Cap, 8-Noise reduction component, 801-First sound receiving device, 802-Second sound receiving device, 803-Speaker, 9-Sound absorption component, 901-Disc, 902-Through hole, 903-Filter screen, 904-Outer ring, 905-Sound absorbing felt layer. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figures 1 to 8 As shown: The ventilation structure with noise reduction function includes a first pipe body 1, a fan 2, a second pipe body 3, a pipe assembly, a cover 7, and a noise reduction component 8. The first pipe body 1, the fan 2, the second pipe body 3, the pipe assembly, and the cover 7 are connected in sequence. The cover 7 is installed on the outside of the building for communication with the outdoor air.

[0023] The noise reduction assembly 8 includes a first sound receiving device 801 disposed on the cover 7, a second sound receiving device 802 disposed inside the first tube 1, and a loudspeaker 803. The first sound receiving device 801 is used to collect outdoor ambient noise signals in real time, and the second sound receiving device 802 is used to collect indoor noise signals; the loudspeaker 803 is used to emit reverse sound waves with the opposite phase to the noise signals, thereby canceling out low-frequency noise transmitted through the ventilation structure in the indoor space.

[0024] The noise reduction component 8 also includes a signal processing unit. The signal processing unit performs a Fast Fourier Transform (FFT) operation on the noise signal collected by the radio equipment to obtain the spectral characteristics of the noise signal, and iteratively optimizes the reverse sound wave output by the speaker 803 based on a Least Mean Square (LMS) adaptive filtering algorithm. Simultaneously, the signal processing unit, considering noise levels, air quality parameters, and user-defined operating modes, automatically adjusts the speed of the fan 2 and the output parameters of the speaker 803 using a fuzzy control algorithm, thereby achieving the best noise reduction effect while ensuring indoor air circulation.

[0025] In terms of specific structure, there are four first sound receiving devices 801. The four first sound receiving devices 801 are evenly distributed in an array on the cover 7 to collect outdoor noise signals at multiple points, so as to improve the accuracy and stability of noise collection.

[0026] The pipe assembly includes a first branch pipe 4 and a second branch pipe 5. The first branch pipe 4 has a sound-absorbing component 9 installed inside to absorb and reduce noise energy. The inner wall of the second branch pipe 5 is machined to a smooth structure to reduce airflow resistance. The axis of the second branch pipe 5 is parallel to the axis of the second pipe body 3, while the axis of the first branch pipe 4 forms a certain angle with the axis of the second pipe body 3 to enhance the refraction and absorption of sound waves within the pipe.

[0027] The sound-absorbing component 9 comprises at least two discs 901, through holes 902, a filter 903, an outer ring 904, and a sound-absorbing felt layer 905. At least two discs 901 are fixedly installed on the inner wall of the first branch pipe 4. Each disc 901 has a through hole 902, and the filter 903 is disposed at the through hole 902 to block particulate matter from entering. The outer ring 904 is connected to the edge of the disc 901, and the sound-absorbing felt layer 905 is connected to the outer side of the outer ring 904. The sound-absorbing felt layer 905 covers the gap between the disc 901 and the pipe wall, further absorbing airflow noise passing through the through holes 902. The through holes 902 on adjacent discs 901 are staggered, causing continuous diffraction and attenuation of sound waves during propagation, thereby significantly improving the noise reduction effect.

[0028] In actual use, outdoor air enters the room sequentially through the cover 7, the second pipe 3, the pipe assembly, and the first pipe 1 under the action of the fan 2. The first sound receiving device 801 collects outdoor noise signals in real time, and the second sound receiving device 802 collects indoor residual noise signals. The signal processing unit analyzes and processes the two signals and controls the speaker 803 to emit corresponding reverse sound waves to achieve active noise reduction. At the same time, the sound-absorbing component 9 in the first branch pipe 4 passively absorbs mid-to-high frequency noise during airflow, thus working in conjunction with active noise reduction to effectively improve the overall noise reduction effect. The ventilation structure described in this embodiment can effectively reduce the intensity of external noise entering the room while ensuring air circulation, especially showing a significant suppression effect on low-frequency noise, making it suitable for indoor places with high requirements for the acoustic environment.

[0029] like Figure 3 and Figure 4 As shown: The control mechanism 6 includes two rotating shafts 609, two brake pads 608, a support base 606, a moving base 602, a limit plate 607, an electric push rod 601, a rotating shaft 603, a groove 605, a crossbeam 604, and a hydraulic cylinder 610.

[0030] Two rotating shafts 609 are rotatably connected to the first branch pipe 4 and the second branch pipe 5, respectively. Two brake pads 608 are fixedly connected to the rotating shafts 609, used to open or close the pipeline as the rotating shafts 609 rotate. The rotating shafts 609 are supported by a support base 606, which has a sliding connection with a limiting plate 607. The limiting plate 607 is fixedly connected to a movable seat 602, which is rotatably connected to the support base 606 via a rotating shaft 603. One end of an electric push rod 601 is connected to the support base 606, and its output end is connected to the movable seat 602. A trough 605 is machined on a crossbeam 604, and the rotating shaft 603 is slidably installed inside the trough 605. The crossbeam 604 is fixedly connected to the output end of a hydraulic cylinder 610 to achieve linear reciprocating motion of the crossbeam 604.

[0031] In this embodiment, two protective nets 10 are also included. The two protective nets 10 are respectively installed at the openings of the first branch pipe 4 and the second branch pipe 5 to prevent foreign objects from entering the pipes and to ensure the safety and reliability of the system operation.

[0032] In actual use, the electric push rod 601 drives the movable seat 602, causing the rotating shaft 603 to adjust its position within the trough 605. After this adjustment, when the hydraulic cylinder 610 drives the crossbeam 604 to move, the crossbeam 604 causes the trough 605 and the rotating shaft 603 to move accordingly, thereby changing the rotation amplitude of the two brake plates 608 and adjusting the air intake volume inside the first branch pipe 4 and the second branch pipe 5.

[0033] Specifically, the control mechanism 6 can achieve the following working states as needed: Air volume ratio adjustment: By adjusting the position of the rotating shaft 603 in the trough 605, the two dampers 608 can produce different opening and closing angles, thereby changing the air volume ratio between the first branch pipe 4 and the second branch pipe 5.

[0034] Completely closed / open: When the brake plate 608 is in a specific extreme position, it can completely close the first branch pipe 4 while keeping the second branch pipe 5 open, or completely close the second branch pipe 5 while keeping the first branch pipe 4 open.

[0035] Default state: When no adjustment command is received, the two brake pads 608 are kept perpendicular to each other, thereby achieving the basic ventilation mode.

[0036] Through the above structural design, the control mechanism 6 in this embodiment can flexibly control the air intake of the first branch pipe 4 and the second branch pipe 5, which not only improves the adaptability and energy efficiency of the ventilation system, but also can automatically adjust according to noise reduction and air exchange requirements under different working conditions.

[0037] In addition, this invention discloses a control method for a ventilation structure with noise reduction function, applicable to the aforementioned ventilation structure. This method, by setting multiple operating modes and based on the opening and closing angles of the two dampers 608 in the control mechanism 6, adjusts the airflow distribution to the first branch pipe 4 and the second branch pipe 5, thereby balancing air exchange and noise reduction requirements.

[0038] The control method includes the following steps: Pattern recognition and startup: The signal processing unit automatically identifies the required operating mode based on outdoor noise intensity, indoor residual noise level, air quality parameters, and user preset requirements. When no user command is received or environmental parameters do not reach the threshold, the system enters the default ventilation mode.

[0039] Operating mode settings: The system can be switched to the following modes: (1) Default ventilation mode The two brake pads 608 are perpendicular to each other; Both the first branch pipe 4 and the second branch pipe 5 remain partially open; Ensure adequate ventilation to maintain indoor air circulation.

[0040] (2) Low noise priority mode The brake pad 608 of the first branch pipe 4 is kept at a large opening, while the opening of the brake pad 608 of the second branch pipe 5 is reduced. Air is mainly introduced through the first branch pipe 4, which is equipped with sound-absorbing components 9, to enhance the passive noise reduction effect; Combined with active noise reduction algorithms, it minimizes the noise entering the room.

[0041] (3) Air exchange priority mode The brake pad 608 of the second branch pipe 5 is kept at a large opening, while the brake pad 608 of the first branch pipe 4 is partially closed; This allows air to enter primarily through the second branch pipe 5, which has lower resistance, thus improving ventilation efficiency. Suitable for scenarios with poor air quality or where rapid air replacement is required.

[0042] (4) Directional noise reduction mode By adjusting the position of the rotating shaft 603 in the groove 605, the two brake pads 608 can produce different opening and closing angles; To achieve the adjustment of the mixed air intake ratio between the first branch pipe 4 and the second branch pipe 5; While ensuring adequate ventilation, it is necessary to balance the needs of noise reduction and air circulation.

[0043] (5) Fully closed / single tube mode When the ambient noise is too high or special operating conditions are required, control a certain branch gate plate 608 to be completely closed; Maintain a separate air intake for another branch pipe to meet specific noise reduction or ventilation needs.

[0044] Dynamic adjustment process: During system operation, the signal processing unit collects noise signals and air quality parameters in real time; Based on the fuzzy control algorithm, the actions of the electric push rod 601 and the hydraulic cylinder 610 are dynamically adjusted to change the opening degree of the brake plate 608. It enables automatic switching or fine-tuning between modes to ensure optimal ventilation and noise reduction under different environmental conditions.

[0045] The following illustrates the process of controlling the opening degree of the two brake pads 608 according to the pattern: class VentilationController: def __init__(self, hw): self.hw = hw self.mode = "default" # Default mode def set_mode(self, mode): Switch running mode self.mode = mode if mode == "low_noise": angle1, angle2 = 70, 20 # First branch pipe prioritizes sound absorption elif mode == "air_exchange": angle1, angle2 = 20, 70 # Second branch pipe prioritizes ventilation else: # Default mode angle1, angle2 = 45°, 45° # Two-tube balancing self.hw.set_gate_angles(angle1, angle2).

[0046] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A ventilation structure with noise reduction function, characterized in that: It includes a first pipe body (1), a fan (2), a second pipe body (3), a pipe assembly, a cover (7), and a noise reduction component (8); The first pipe body (1), the fan (2), the second pipe body (3), the pipe group and the cover (7) are connected in sequence, and the cover (7) is set outdoors; The noise reduction assembly (8) includes a first radio receiver (801) disposed on the cover (7), a second radio receiver (802) disposed inside the first tube (1) and a speaker (803).

2. The ventilation structure with noise reduction function according to claim 1, characterized in that: The first radio receiver (801) is used to collect outdoor ambient noise signals, the second radio receiver (802) is used to collect indoor noise signals, and the loudspeaker (803) is used to emit a reverse sound wave with the opposite phase to the noise signal to cancel the low-frequency noise entering the room.

3. The ventilation structure with noise reduction function according to claim 1, characterized in that: The number of the first radio receivers (801) is four, and the four first radio receivers (801) are arrayed on the cover (7).

4. The ventilation structure with noise reduction function according to claim 1, characterized in that: The pipe assembly includes a first branch pipe (4) and a second branch pipe (5); the first branch pipe (4) is provided with a sound-absorbing component (9) inside, and the inner wall of the second branch pipe (5) is smooth.

5. The ventilation structure with noise reduction function according to claim 4, characterized in that: The axis of the second branch pipe (5) is parallel to the axis of the second pipe body (3), and the axis of the first branch pipe (4) is at an angle to the axis of the second pipe body (3).

6. The ventilation structure with noise reduction function according to claim 4, characterized in that: The sound-absorbing component (9) includes at least two discs (901), through holes (902), a filter (903), an outer ring (904), and a sound-absorbing felt layer (905). At least two of the discs (901) are disposed on the inner wall of the first branch pipe (4), the through hole (902) is opened on the disc (901), the filter screen (903) is connected to the through hole (902), the outer ring (904) is connected to the disc (901), and the outer ring (904) is connected to the sound-absorbing felt layer (905); The through holes (902) on adjacent disks (901) are misaligned.

7. The ventilation structure with noise reduction function according to claim 5, characterized in that: It also includes a control mechanism (6), which includes two rotating shafts (609), a brake plate (608), a support base (606), a moving base (602), a limit plate (607), an electric push rod (601), and a rotating shaft (603), as well as one groove (605), a crossbeam (604), and a hydraulic cylinder (610). The two rotating shafts (609) are rotatably connected to the first branch pipe (4) and the second branch pipe (5) respectively. The brake plate (608) is connected to the rotating shaft (609). The rotating shaft (609) is connected to the support seat (606). The support seat (606) is slidably connected to the limiting plate (607). The limiting plate (607) is connected to the moving seat (602). The moving seat (602) is rotatably connected to the rotating shaft (603). The support seat (606) is connected to the electric push rod (601). The output end of the electric push rod (601) is connected to the moving seat (602). The groove (605) is machined on the crossbeam (604). The rotating shaft (603) is slidably connected to the groove (605). The crossbeam (604) is connected to the output end of the hydraulic cylinder (610).

8. The ventilation structure with noise reduction function according to claim 4, characterized in that: It also includes two protective nets (10), which are respectively connected to the first branch pipe (4) and the second branch pipe (5).

9. A control method for a ventilation structure with noise reduction function, using the ventilation structure with noise reduction function as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1 Pattern Recognition and Startup: The signal processing unit automatically identifies the required operating mode based on outdoor noise intensity, indoor residual noise level, air quality parameters, and user preset requirements. When no user command is received or environmental parameters do not reach the threshold, the system enters the default ventilation mode. S2 operating mode settings: Based on the pattern identified in step S1, the system switches its operating mode; S3 Dynamic Adjustment Process: During system operation, the signal processing unit collects noise signals and air quality parameters in real time; Based on the fuzzy control algorithm, the action of the electric push rod (601) and the hydraulic cylinder (610) is dynamically adjusted to change the opening degree of the brake plate (608), so as to realize automatic switching or fine adjustment between modes, so as to ensure the best ventilation and noise reduction effect under different environmental conditions.

10. The control method for a ventilation structure with noise reduction function according to claim 9, characterized in that: S2 further includes: S2.1 Default ventilation mode: The two dampers (608) are perpendicular to each other, and the first branch pipe (4) and the second branch pipe (5) are both partially open to ensure basic ventilation and maintain indoor air circulation; S2.2 Low noise priority mode: The damper (608) of the first branch pipe (4) is kept at a large opening, and the damper (608) of the second branch pipe (5) is reduced, so that air mainly enters through the first branch pipe (4) equipped with sound-absorbing components (9), which enhances the passive noise reduction effect and reduces indoor noise in conjunction with the active noise reduction algorithm; S2.3 Air exchange priority mode: The damper (608) of the second branch pipe (5) is kept at a large opening, and the damper (608) of the first branch pipe (4) is partially closed, so that air mainly enters through the second branch pipe (5) with less resistance, thereby improving ventilation efficiency. It is suitable for scenarios with poor air quality or those that require rapid air replacement. S2.4 Directional noise reduction mode: By adjusting the position of the rotating shaft (603) in the trough (605), the two brake plates (608) produce different opening and closing angles, thereby realizing the adjustment of the mixed air intake ratio of the first branch pipe (4) and the second branch pipe (5), balancing noise reduction and air circulation while ensuring ventilation volume; S2.5 Fully Closed / Single Pipe Mode: When the ambient noise is too high or special operating conditions are required, control one branch pipe damper (608) to be completely closed, and keep the other branch pipe to enter the air separately to meet specific noise reduction or ventilation needs.

Images