Air duct silencing device, air conditioner and control method of air conditioner

Abstract

The invention discloses an air duct silencing device, an air conditioner and a control method of the air conditioner. The air duct silencing device comprises a silencer, a top cover, a bottom cover and a shielding piece, the top cover and the bottom cover are arranged at the top and the bottom of the silencer in a covering mode respectively, at least one resonant cavity structure is arranged in the silencer, each resonant cavity structure comprises a resonant cavity and a sound absorption opening, and the shielding piece is arranged in the resonant cavity. The sound absorption opening is formed in the side wall of the silencer and is communicated with the resonant cavity in the radial direction of the silencer, an open hole communicated with the resonant cavity in the axial direction of the silencer is formed in the top cover, and the shielding piece is rotationally arranged on the top cover and shields the open hole so as to adjust the size of the open hole. The hole opening area is dynamically controlled through the shielding piece capable of being rotationally adjusted, real-time adjustment of the resonant frequency of the silencer is achieved, therefore, noise frequencies under different working conditions are effectively matched, and the low-frequency noise absorption effect is remarkably improved while the ventilation performance is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air conditioners, in particular to an air duct sound absorbing device, an air conditioner and a control method thereof. BACKGROUND

[0002] The indoor unit of a cabinet air conditioner generates various noises during operation, mainly including mechanical noise generated during fan operation, aerodynamic noise formed by air flowing inside the air duct, and "hum" or "whoosh" sound generated when air flows through the fan blades. These noises generally have the spectral characteristics of low-frequency broadband, making it difficult for conventional sound insulation or sound absorption materials to effectively reduce noise optimization. As a leading noise reduction technology, acoustic metamaterials can achieve sound absorption and insulation effects by designing resonance cavities, expanding acoustic paths, and creating sound interference. However, in the context of air conditioner air ducts, most of these materials do not fully consider the ventilation performance, making it difficult to apply them while ensuring sufficient air volume in the air conditioner air duct. This results in the current cabinet air conditioner indoor unit being unable to solve the problem of low-frequency broadband noise with conventional materials, and unable to reasonably utilize acoustic metamaterials for noise reduction without affecting the normal performance of the air conditioner. Therefore, there is an urgent need for a technical solution that takes into account low-frequency broadband noise reduction effect, ventilation performance, and adapts to the application scenario of air conditioners. SUMMARY

[0003] Embodiments of the present application provide an air duct sound absorbing device, an air conditioner and a control method thereof, aiming to solve the problem of reducing low-frequency broadband noise without affecting the ventilation performance of the air duct.

[0004] The present application provides an air duct sound absorbing device, comprising: a sound absorber, a top cover, a bottom cover and a shielding piece, the top cover and the bottom cover are respectively arranged on the top and bottom of the sound absorber, at least one resonance cavity structure is arranged inside the sound absorber, each resonance cavity structure comprises a resonance cavity and a sound absorption port, the sound absorption port is arranged on the side wall of the sound absorber and penetrates the resonance cavity along the radial direction of the sound absorber, and an opening is arranged on the top cover and penetrates the resonance cavity along the axial direction of the sound absorber, wherein the shielding piece is rotatably arranged on the top cover and shields the opening to adjust the size of the opening.

[0005] Further, each resonance cavity structure further comprises a neck portion, the resonance cavity structure is formed by a pair of Helmholtz resonators, a first Helmholtz resonator takes the sound absorption port as its inlet and is arranged around the outer periphery of a second Helmholtz resonator, the inside of the second Helmholtz resonator is enclosed to form the resonance cavity, and the path channel between the inlet of the first Helmholtz resonator and the inlet of the second Helmholtz resonator is defined by the inside of the first Helmholtz resonator and the outside of the second Helmholtz resonator to form the neck portion.

[0006] Furthermore, the inlet of the second Helmholtz resonator is arranged in the opposite direction to the inlet of the first Helmholtz resonator along the radial direction of the silencer.

[0007] Furthermore, both the first Helmholtz resonator and the second Helmholtz resonator have a fan-shaped structure. The entrance of the first Helmholtz resonator is located at the arc of the fan-shaped structure, and the entrance of the second Helmholtz resonator is located at the central corner of the fan-shaped structure.

[0008] Furthermore, the sound-absorbing port has a slit structure, and the sound-absorbing port extends from the bottom to the top of the muffler along its axial direction.

[0009] Furthermore, the resonant cavity structure is provided in multiple ways, and the multiple resonant cavity structures are evenly distributed along the circumference of the muffler.

[0010] Furthermore, the duct silencing device also includes a driving component. The top cover has multiple openings that are respectively connected to the multiple resonant cavities. Each opening extends circumferentially along the silencer to form an arc-shaped opening. The shielding component includes a rotating shaft and multiple shielding blades. The multiple shielding blades are respectively fixedly connected to the rotating shaft along the circumferential direction of the rotating shaft. Each shielding blade shields one of the openings. The rotating shaft passes through the center of the top cover, the silencer and the bottom cover in sequence and is connected to the driving component.

[0011] Secondly, the present invention also provides an air conditioner, including an air duct and an air duct silencing device, wherein the air duct silencing device is the aforementioned air duct silencing device, the air duct has a sound outlet, and the air duct silencing device is located outside the air duct with its sound absorption port aligned with the sound outlet.

[0012] Thirdly, the present invention also provides a control method for an air conditioner, applied to the aforementioned air conditioner, the method comprising:

[0013] Get the current fan speed setting of the air conditioner;

[0014] The current operating windshield drives the shielding component to rotate to the target opening position corresponding to the current operating windshield, wherein each operating windshield corresponds one-to-one with multiple different opening positions of the shielding component.

[0015] Furthermore, the method also includes:

[0016] Adjust the operating windshield to the lowest operating windshield and drive the blocking member to rotate until it completely blocks the opening;

[0017] Acquire the time-domain noise signal in the air duct and convert the time-domain noise signal into an octave band spectrum, and record the center frequency of the highest frequency band of the noise value in the octave band spectrum;

[0018] The center frequency is used as the reference resonant frequency, and the size parameters of the resonant cavity structure are determined according to the Helmholtz resonant frequency formula based on the reference resonant frequency.

[0019] Adjust the operating windshield to the next operating windshield, obtain the current center frequency of the air duct and the current resonance frequency of the resonant cavity structure, and drive the shielding member to rotate and adjust the opening size so that the current center frequency is consistent with the current resonance frequency, and mark the current opening position of the shielding member;

[0020] Continue adjusting the next operating windshield and marking the corresponding opening position until all operating windshields are marked.

[0021] This invention provides a duct silencing device, an air conditioner, and a control method thereof. The duct silencing device includes a silencer, a top cover, a bottom cover, and a shielding component. The top cover and bottom cover are respectively installed on the top and bottom of the silencer. The silencer has at least one resonant cavity structure inside, each resonant cavity structure including a resonant cavity and a sound-absorbing port. The sound-absorbing port is opened on the side wall of the silencer and communicates with the resonant cavity along the radial direction of the silencer. The top cover has an opening that communicates with the resonant cavity along the axial direction of the silencer. The shielding component is rotatably installed on the top cover and blocks the opening to adjust the size of the opening. This invention dynamically controls the opening area through the rotatable and adjustable shielding component, realizing real-time adjustment of the resonant frequency of the silencer, thereby effectively matching the noise frequency under different operating conditions and significantly improving the absorption effect of low-frequency noise while ensuring ventilation performance. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is an exploded schematic diagram of the duct silencing device according to an embodiment of the present invention;

[0024] Figure 2 This is a top view schematic diagram of the silencer of the duct silencer device according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the duct silencing device according to an embodiment of the present invention;

[0026] Figures 4a-4c This is a schematic diagram of the assembly of the duct silencing device and the duct in an embodiment of the present invention;

[0027] Figure 5 for Figure 4a Enlarged view of part A;

[0028] Figure 6 This is a simulation diagram of the duct silencing device according to an embodiment of the present invention;

[0030] 100. Duct silencer; 10. Top cover; 11. Opening; 20. Silencer; 21. Resonance cavity structure; 211. Resonance cavity; 212. Sound absorption port; 213. Neck; 201. First Helmholtz resonator; 202. Second Helmholtz resonator; 202a. Inlet of the second Helmholtz resonator; 30. Bottom cover; 40. Shielding component; 41. Rotating shaft; 42. Shielding blade; 200. Duct. Detailed Implementation

[0031] 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, not all, of the embodiments of the present invention. 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.

[0032] The directional terms used in this invention, such as "up," "down," "front," "back," "left," "right," "inner," "outer," and "side," are merely for reference to the accompanying drawings. Therefore, the directional terms used are for illustrating and understanding this invention, and not for limiting it. Furthermore, in the drawings, structures that are similar or identical are indicated by the same reference numerals.

[0033] In the field of air conditioning duct noise control, effective suppression of low-frequency broadband noise has always been a technical challenge. Traditional sound insulation materials often fail to meet noise reduction requirements due to insufficient low-frequency sound absorption performance. While acoustic metamaterials can achieve low-frequency sound absorption, they generally suffer from the drawback of obstructing airflow and affecting ventilation performance. Especially for cabinet air conditioners, the mechanical noise generated by fan operation, the aerodynamic noise generated by airflow disturbance in the duct, and the periodic noise caused by blade rotation all exhibit typical low-frequency broadband characteristics. These noises are not only wide-bandwidth but also concentrated in energy, making it difficult for conventional sound absorption structures to achieve effective control without significantly reducing airflow. In existing technologies, fixed-frequency Helmholtz resonators can achieve sound absorption for specific frequency bands, but they cannot adapt to the noise spectrum changes during the variable operating conditions of air conditioners. Moreover, most designs do not fully consider ventilation requirements, resulting in a difficulty in balancing noise reduction performance and airflow maintenance. Therefore, developing a silencing device that can maintain duct ventilation performance while dynamically adjusting to adapt to low-frequency noise under different operating conditions has become a key technical problem that urgently needs to be solved to improve the acoustic quality of air conditioners. Therefore, this application proposes a duct silencer, an air conditioner, and a control method thereof to address the problem of reducing low-frequency broadband noise without affecting the ventilation performance of the duct.

[0034] Please see Figures 1 to 5 , Figure 1 An air duct silencing device 100 according to an embodiment of the present invention includes: a silencer 20, a top cover 10, a bottom cover 30, and a shielding member 40. The top cover 10 and the bottom cover 30 are respectively installed on the top and bottom of the silencer 20. The silencer 20 has at least one resonant cavity structure 21 inside. Each resonant cavity structure 21 includes a resonant cavity 211 and a sound absorption port 212. The sound absorption port 212 is opened on the side wall of the silencer 20 and communicates with the resonant cavity 211 along the radial direction of the silencer 20. The top cover 10 has an opening 11 that communicates with the resonant cavity 211 along the axial direction of the silencer 20. The shielding member 40 is rotatably installed on the top cover 10 and shields the opening 11 to adjust the size of the opening 11.

[0035] Specifically, the silencer 20 can take the form of various common three-dimensional structures such as cylindrical or square. Its core function is to provide a mounting carrier for the internal resonant cavity structure 21 and to absorb duct noise through the resonant cavity structure 21. The top cover 10 and bottom cover 30 can adopt plate-shaped structures adapted to the shape of the silencer 20. Their function is to seal the top and bottom openings of the silencer 20 to prevent foreign objects from entering the silencer 20 and affecting the sound absorption effect of the resonant cavity structure 21. The shielding component 40 can be designed as a circular baffle, arc-shaped blade, or other rotatable structure. Its main function is to change the shielding area of ​​the opening 11 on the top cover 10 by rotating it, thereby adjusting the size of the opening 11. The top cover 10 and bottom cover 30 are respectively installed on the top and bottom of the muffler 20 by bolt connection, snap-fit, etc., so that the three together form a closed muffler cavity. The resonant cavity structure 21 inside the muffler 20 can be set by integral molding, welding and fixing, etc. The sound absorption port 212 of each resonant cavity structure 21 is opened radially on the side wall of the muffler 20 and communicates with the inside of the resonant cavity 211, ensuring that the noise in the air duct can enter the resonant cavity 211 radially. The opening 11 on the top cover 10 is opened axially along the muffler 20 and communicates with the inside of the resonant cavity 211. The shielding member 40 is rotatably installed on the side of the top cover 10 facing the muffler 20 or away from the muffler 20 by means of shaft 41 connection, bearing and other means, and the coverage area of ​​the shielding member 40 can completely cover the opening 11. By incorporating a resonant cavity structure 21 within the muffler 20, noise is absorbed through the acoustic resonance effect of the resonant cavity 211. Simultaneously, the size of the opening 11 is adjusted using a rotatable shielding component 40, thereby altering the equivalent volume of the resonant cavity 211 or the neck 213 parameters, thus adapting to noise at different frequencies. The opening 11 on the top cover 10 and the sound-absorbing port 212 on the side wall of the muffler 20 are respectively arranged axially and radially, without obstructing the internal space of the duct, thus avoiding impact on airflow. Therefore, it can adapt to noise frequency variations under different duct operating conditions, achieving flexible noise reduction without hindering duct ventilation, balancing noise reduction and ventilation performance. Furthermore, its diverse structural forms allow for the selection of appropriate component structures based on different duct scenarios.

[0036] Reference Figure 2 In one embodiment, each of the resonant cavity structures 21 further includes a neck 213. The resonant cavity structure 21 is formed by a pair of Helmholtz resonators. The first Helmholtz resonator 201 takes the sound-absorbing port 212 as its entrance and surrounds the outer periphery of the second Helmholtz resonator 202. The inner side of the second Helmholtz resonator 202 surrounds to form the resonant cavity 211. The path between the entrance of the first Helmholtz resonator 201 and the entrance of the second Helmholtz resonator 202 is defined by the inner side of the first Helmholtz resonator 201 and the outer side of the second Helmholtz resonator 202, which defines the neck 213.

[0037] Specifically, each of the resonant cavity structures 21 further includes a neck 213, which is a channel structure connecting the inlet and the resonant cavity 211. Its length directly affects the noise reduction frequency band of the Helmholtz resonator; the longer the neck 213, the lower the noise reduction frequency band that can be achieved. The resonant cavity structure 21 is formed by a pair of Helmholtz resonators. The first Helmholtz resonator 201 and the second Helmholtz resonator 202 are both structures with cavities and inlets. The first Helmholtz resonator 201 uses the sound absorption port 212 as its inlet, which is entirely surrounded on the outer periphery of the second Helmholtz resonator 202, forming an annular gap between them. The inner side of the second Helmholtz resonator 202 encloses the resonant cavity 211, and its inlet communicates with the resonant cavity 211. The path between the inlet of the first Helmholtz resonator 201 and the inlet 202a of the second Helmholtz resonator is defined by the inner wall of the first Helmholtz resonator 201 and the outer wall of the second Helmholtz resonator 202, forming a neck 213. In other words, the neck 213 is an annular channel between the two resonators. The neck 213 of a conventional single Helmholtz resonator is relatively short, making it difficult to handle low-frequency broadband noise. Compared to the short neck 213 of a single Helmholtz resonator, the structure in this embodiment significantly extends the length of the neck 213. After noise enters from the sound-absorbing port 212 (the inlet of the first Helmholtz resonator 201), it must pass through the longer neck 213 channel to reach the inlet of the second Helmholtz resonator 202 and enter the resonant cavity 211. The extended neck 213 lowers the resonant frequency, thereby effectively attenuating lower-frequency noise. The nested design of the two Helmholtz resonators extends the length of the neck 213, significantly widening the silencing frequency range, especially enhancing the silencing capability for low-frequency noise and improving the device's adaptability to broadband noise.

[0038] Continue to refer to Figure 2In this embodiment, the inlet 202a of the second Helmholtz resonator and the inlet of the first Helmholtz resonator 201 are arranged in opposite directions along the radial direction of the muffler 20. Specifically, the two Helmholtz resonators are arranged in an anti-symmetrical manner, that is, the inlet 202a of the second Helmholtz resonator and the inlet of the first Helmholtz resonator 201 are arranged in opposite directions along the radial direction of the muffler 20. The inlet (212) of the first Helmholtz resonator 201 is arranged outward along the radial direction of the muffler 20, that is, the inlet direction points to the side wall of the muffler 20; the inlet 202a of the second Helmholtz resonator is arranged inward along the radial direction of the muffler 20, that is, the inlet direction points to the center of the muffler 20. The inlet directions of the two are completely opposite. The opposing inlet orientations of the two Helmholtz resonators distance them from each other. The inlet of the first Helmholtz resonator 201 is closer to the side wall of the silencer 20, while the inlet of the second Helmholtz resonator 202a is closer to the center of the silencer 20, maximizing the distance between them and thus maximizing the length of the neck 213 formed between the two resonators. Consequently, the longer the neck 213, the lower the resonant frequency, allowing for better adaptation to even lower frequency noise. Maximizing the length of the neck 213 further reduces the silencing frequency of the resonant cavity structure 21, enhancing the absorption effect on extremely low-frequency noise within the duct and improving the performance of the duct silencer 100 in low-frequency noise control.

[0039] Continue to refer to Figure 2In a specific embodiment, both the first Helmholtz resonator 201 and the second Helmholtz resonator 202 have a fan-shaped structure. The entrance of the first Helmholtz resonator 201 is located at the arc of the fan-shaped structure, and the entrance 202a of the second Helmholtz resonator is located at the central corner of the fan-shaped structure. Specifically, the fan-shaped structure of both the first Helmholtz resonator 201 and the second Helmholtz resonator 202 maximizes the acoustic length of the neck 213 between the two resonators within the limited space inside the muffler 20, while reducing the space occupied inside the muffler 20. In the fan-shaped structure of the first Helmholtz resonator 201, the side containing the arc, which is also the sidewall of the muffler 20, has its inlet located at the arc, meaning the sound-absorbing port 212 of the muffler 20's sidewall is located at the arc. The fan-shaped structure of the second Helmholtz resonator 202 is nested within the fan-shaped cavity of the first Helmholtz resonator 201, with its central angle facing the center of the muffler 20, and its inlet located at the central angle. The centers of the two fan-shaped structures are collinear, and the annular gap between them forms the neck 213. By placing the inlet of the first Helmholtz resonator 201 at the arc and the inlet 202a of the second Helmholtz resonator at the central angle, the path of noise from the inlet of the first Helmholtz resonator 201 to the inlet 202a of the second Helmholtz resonator can be extended without increasing the overall volume of the muffler 20, i.e., extending the acoustic length of the neck 213. A longer acoustic length can lower the resonant frequency, achieving absorption of lower frequency noise. Therefore, without occupying too much space in the duct or affecting the ventilation, the acoustic length of the neck 213 is further extended, enabling the duct silencer 100 to absorb noise in a lower frequency band, improving the low-frequency silencer performance, and optimizing the space utilization inside the silencer 20.

[0040] Reference Figure 3In one embodiment, the sound-absorbing port 212 is a slit structure, extending from the bottom to the top of the muffler 20 along its axial direction. Specifically, the slit structure of the sound-absorbing port 212 in this embodiment maximizes the utilization of the sidewall space of the muffler 20 while ensuring comprehensive absorption of noise at different heights within the duct, without excessively weakening the structural strength of the muffler 20's sidewall. The slit-shaped sound-absorbing port 212 is opened along the axial direction of the muffler 20 on its sidewall, with its length consistent with the height of the muffler 20, extending from the bottom to the top of the muffler 20. Each resonant cavity structure 21 corresponds to at least one slit-shaped sound-absorbing port 212, and the sound-absorbing port 212 remains in communication with the interior of the resonant cavity 211, enabling direct absorption of noise within the duct and near the fan blades. Compared to non-slit openings such as circles and squares, the slit structure extends completely along the axial direction, covering different height positions within the air duct and avoiding blind spots where "local noise is not absorbed" due to the limited coverage of the opening height. Simultaneously, the narrow design of the slit ensures that noise enters the resonant cavity 211 directly through the slit (short and direct sound absorption path) without excessively weakening the structural strength of the silencer 20's sidewalls. Furthermore, the radially opened narrow slit does not create a significant "blocking surface" for the airflow that mainly flows axially within the air duct, avoiding airflow loss due to the design of the sound absorption port 212. Therefore, it improves the absorption range and uniformity of noise within the air duct, more comprehensively absorbing noise within the air duct and near the fan blades, while ensuring the structural stability of the silencer 20. This achieves compatibility between "high-efficiency sound absorption" and "ensuring ventilation," and the adaptation solution addresses the core requirements of both noise reduction and ventilation performance.

[0041] In one embodiment, multiple resonant cavity structures 21 are provided, and these multiple resonant cavity structures 21 are evenly distributed along the circumference of the silencer 20. Specifically, multiple resonant cavity structures 21 are provided, and these multiple resonant cavity structures 21 are evenly distributed along the circumference of the silencer 20, that is, the included angle between two adjacent resonant cavity structures 21 is equal (e.g., when three resonant cavity structures 21 are provided, the adjacent spacing is 120°). Each resonant cavity structure 21 includes components such as a resonant cavity 211 and a sound-absorbing port 212. The sound-absorbing ports 212 are respectively opened at corresponding positions on the side wall of the silencer 20, and the openings 11 on the top cover 10 also correspond one-to-one with each resonant cavity structure 21. The multiple resonant cavity structures 21 evenly distributed around the circumference can receive noise from different circumferential positions of the air duct, avoiding the dead angles of noise attenuation caused by uneven noise distribution around the circumference of the air duct. Through the synergistic effect of multiple sets of resonant cavities 211, the noise in the air duct is comprehensively attenuated. This enables the silencing device to uniformly handle noise around the duct, eliminate silencing blind spots, and improve the uniformity of the overall silencing effect. At the same time, multiple resonant cavity structures 21 can be assigned to different frequencies of noise, further widening the silencing frequency range.

[0042] Reference Figure 1 and Figure 3In one embodiment, the duct silencing device 100 further includes a driving component. The top cover 10 has multiple openings 11 that respectively communicate with the multiple resonant cavities 211. Each opening 11 extends circumferentially along the silencer 20 to form an arc-shaped opening 11. The blocking component 40 includes a rotating shaft 41 and multiple blocking blades 42. The multiple blocking blades 42 are fixedly connected to the rotating shaft 41 circumferentially. Each blocking blade 42 blocks one opening 11. The rotating shaft 41 passes sequentially through the center of the top cover 10, the silencer 20, and the bottom cover 30 and is connected to the driving component. Specifically, the driving component is a device capable of providing rotational power, such as a servo motor or a stepper motor, used to drive the blocking component 40 to rotate. The top cover 10 has multiple openings 11, each corresponding to a plurality of resonant cavities 211 and passing through the axial direction of the muffler 20. Each opening 11 extends circumferentially along the muffler 20 to form an arc shape, the length of which can be adjusted within the range. The shielding component 40 includes a rotating shaft 41 and multiple shielding blades 42. The rotating shaft 41 is a rod-shaped structure, and the multiple shielding blades 42 are evenly distributed circumferentially along the rotating shaft 41 and fixedly connected to the rotating shaft 41 (e.g., by welding or bolting). The shape of each shielding blade 42 matches the corresponding arc-shaped opening 11 and can cover the opening 11. The rotating shaft 41 passes sequentially through the central holes of the top cover 10, the muffler 20, and the bottom cover 30, and its lower end is connected to the output shaft of the drive component (e.g., by a coupling). The drive component rotates the shaft 41, causing the shielding blades 42 to rotate synchronously. By changing the relative position of the shielding blades 42 and the arc-shaped opening 11, the exposed area of ​​the opening 11 is adjusted, thereby changing the degree of connection between each resonant cavity 211 and the outside world, and adjusting the acoustic characteristics of the resonant cavity 211 to meet the noise reduction requirements of different frequencies. This achieves synchronous adjustment of multiple resonant cavity structures 21, improving operational convenience. The cooperation between the arc-shaped opening 11 and the shielding blades 42 ensures a continuous and stable adjustment process, expands the adjustment range, and enhances the adaptability of the noise reduction device to complex noise environments.

[0043] Reference Figures 4a-5 This invention also provides an air conditioner, including an air duct 200 and an air duct silencing device 100. The air duct silencing device 100 is the same as the air duct silencing device 100 described in the above embodiments. The air duct 200 has a sound outlet, and the air duct silencing device 100 is located outside the air duct 200 with its sound absorption port 212 aligned with the sound outlet. This air duct silencing device 100 has been described in detail in the above embodiments, and for the sake of brevity, it will not be described again here.

[0044] Specifically, the air conditioner in this embodiment includes two core components: a duct 200 and a duct silencer 100. The duct 200 is the main channel for airflow and noise generation within the air conditioner, guiding airflow during operation. The sound outlet is the main area where noise radiates outward from the duct. The duct silencer 100 specifically absorbs noise radiated from the duct's sound outlet while avoiding interference with normal ventilation. The duct silencer 100 is installed entirely outside the duct 200, without intruding into the airflow channel inside. The sound-absorbing port 212 on the duct silencer 100 is precisely aligned with the sound outlet of the duct, ensuring that noise radiated from the sound outlet within the duct 200 can directly enter the resonant cavity structure 21 of the silencer through the sound-absorbing port 212. Conventional air conditioner noise reduction solutions, which incorporate sound-absorbing structures inside the duct, can easily obstruct airflow and reduce ventilation performance. However, this embodiment places the duct sound-absorbing device 100 outside the duct 200, completely eliminating its internal space and avoiding interference with airflow. Simultaneously, the sound-absorbing port 212 is aligned with the sound outlet, directly capturing the noise radiation source and reducing noise diffusion to the outside. Combined with the resonant sound absorption principle of the duct sound-absorbing device 100, it effectively absorbs low-frequency broadband noise. This invention, by placing the duct sound-absorbing device 100 outside the duct 200 and aligning the sound-absorbing port 212 with the duct's sound outlet, achieves efficient absorption of air conditioner duct noise through the structure of the duct sound-absorbing device 100 while avoiding obstruction of airflow within the duct. This reduces the noise level of the air conditioner during operation without affecting its ventilation performance and heat exchange efficiency, thus improving the user experience.

[0045] This invention also provides a control method for an air conditioner, applied to the air conditioner described in the above embodiments, the method comprising steps S1-S2.

[0046] S1. Obtain the current operating fan speed of the air conditioner;

[0047] S2. The current operating windshield drive shielding component is rotated to the target opening position corresponding to the current operating windshield, wherein each operating windshield corresponds one-to-one with multiple different opening positions of the shielding component blocking the opening.

[0048] Specifically, the operating fan speed refers to the different operating levels set by the air conditioner according to airflow demand. Different speeds correspond to different fan speeds, resulting in different frequencies and intensities of duct noise, such as low, medium, and high fan speeds. The opening position refers to the rotational position of the obstruction component (such as obstruction blades) relative to the opening on the top cover. Different opening positions correspond to different obstruction areas of the opening by the obstruction component, thus changing the equivalent parameters of the resonant cavity structure to adapt to different frequency noises.

[0049] This embodiment achieves precise adaptation of the silencing device to different windshield noise levels by associating the operating windshield with the opening position. First, the current operating windshield signal is obtained through the air conditioner's control system (such as the main control chip). This signal can directly originate from the user's windshield setting or the windshield state automatically adjusted by the air conditioner according to environmental requirements. Next, the control system calls a pre-stored "operating windshield-opening position" correspondence table (this table is determined through a pre-calibrated process, and each operating windshield corresponds to an opening position that matches the resonant frequency of the silencing device with the center frequency of the windshield noise). The target opening position is determined based on the current operating windshield. Finally, the control system sends a drive signal to the driving component (such as a motor), driving the shielding component to rotate to the target opening position, completing the parameter adjustment of the silencing device. The frequency characteristics of air conditioner duct noise differ under different operating fan settings. If the silencer remains in a fixed opening position, its resonant frequency cannot adapt to the noise frequency changes, leading to a decrease in noise reduction effect. However, by acquiring the operating fan setting in real time and adjusting it to the corresponding opening position, the resonant frequency of the silencer can always be consistent with the noise center frequency of the current fan setting, ensuring efficient noise reduction under different operating conditions. This invention, through its control method, can adjust the noise reduction frequency in real time, achieving automatic adaptation between the silencer and the air conditioner's operating state without manual intervention. This ensures the air conditioner maintains good noise reduction performance under different fan settings. Furthermore, the operation logic is simple and can be directly integrated into the existing air conditioner control system without adding extra complex operations, improving ease of use and noise reduction stability.

[0050] In one embodiment, the control method of the air conditioner of the present invention further includes: adjusting the operating fan damper to the lowest operating fan damper and driving the shielding member to rotate to completely block the opening; acquiring the time-domain noise signal in the air duct and converting the time-domain noise signal into an octave band spectrum, and recording the center frequency of the highest frequency band of the noise value in the octave band spectrum; using the center frequency as the reference resonant frequency, and determining the size parameters of the resonant cavity structure according to the reference resonant frequency using the Helmholtz resonant frequency formula; adjusting the operating fan damper to the next operating fan damper, acquiring the current center frequency of the air duct and the current resonant frequency of the resonant cavity structure, and driving the shielding member to rotate to adjust the size of the opening so that the current center frequency is consistent with the current resonant frequency, and calibrating the current position of the opening where the shielding member is located; continuing to adjust the next operating fan damper and calibrate the corresponding opening position until all operating fan dampers are calibrated.

[0051] Specifically, the time-domain noise signal refers to the signal recording the change in sound pressure level of noise within the duct over time, reflecting the intensity characteristics of noise at different moments. The octave band spectrum refers to the noise energy distribution graph obtained by dividing the time-domain noise signal into frequency bands according to octave intervals after Fourier transform, used to visually demonstrate the energy strength of noise in different frequency ranges. The center frequency refers to the intermediate reference frequency of each octave band, representing the typical frequency of that band. The resonant frequency refers to the natural frequency at which the resonant cavity structure resonates, determined by the dimensional parameters of the resonant cavity (such as volume, neck length, etc.). When the external noise frequency matches this frequency, the resonant cavity can efficiently absorb noise energy. This embodiment pre-calibrates the correspondence between different operating windshields and opening positions. The specific execution process is as follows: First, adjust the air conditioner's operating fan speed to the lowest setting (e.g., the lowest fan volume), and drive the shielding component to rotate until it completely blocks the opening on the top cover, thus initially sealing the resonant cavity structure. Next, use acoustic sensors, such as microphones installed in the air duct, to collect the time-domain noise signal under this fan speed. Then, use a signal processing module (e.g., the air conditioner's main control chip or an external processor) to convert the time-domain noise signal into an octave band spectrum. Identify and record the frequency band with the highest noise energy from the spectrum; the center frequency corresponding to this frequency band is the target frequency that needs to be absorbed. Finally, use this center frequency as the reference resonant frequency and substitute it into the Helmholtz resonant frequency formula:

[0052]

[0053] Where f is the resonant frequency, c is the speed of sound, and S c l is the cross-sectional area of ​​the neck. c V is the neck length, V is the resonant cavity volume, V = S v l v (Sv is the cross-sectional area of ​​the resonant cavity, and lv is the height of the resonant cavity). The dimensional parameters of the resonant cavity structure (such as cavity volume and neck length) are then deduced to ensure that the inherent resonant frequency of the resonant cavity structure matches the reference resonant frequency. Afterward, the operating windshield is adjusted to the next windshield (such as a medium-low windshield), and the above noise signal acquisition and analysis process is repeated to obtain the current center frequency of the noise under that windshield. Simultaneously, the current resonant frequency of the resonant cavity structure is obtained through the Helmholtz resonant frequency.

[0054]

[0055] Among them, f cLet γ be the current resonant frequency, γ be the adiabatic coefficient of air, A be the opening area of ​​the opening, m be the air mass in the opening area, and P be the atmospheric pressure. The size of the opening is adjusted by rotating the blocking component through a driving component until the current center frequency matches the current resonant frequency. At this point, the opening position of the blocking component is recorded as the calibration position corresponding to that windshield. Finally, the same process is continued to adjust to the next operating windshield, and the opening position calibration of all operating windshields is completed sequentially, forming a complete "operating windshield-opening position" correspondence table. Through a step-by-step calibration process starting from the lowest windshield, the correspondence between different operating windshields and opening positions can be accurately established. The control method in this embodiment has reliable parameter basis. The calibration logic based on octave band spectrum and Helmholtz resonance formula can ensure that the resonant frequency of the resonant cavity structure is accurately matched with the center frequency of the noise of each windshield, providing a prerequisite for the air conditioner to achieve efficient noise reduction across the entire windshield range. Furthermore, the calibration process can be completed during the air conditioner production stage without user operation, balancing technical accuracy and ease of use.

[0056] Reference Figure 6 , Figure 6 The simulation diagram of the sound absorption coefficient of the duct silencing device shows that as the rotation angle of the obstruction increases (i.e., the area of ​​the opening being obstructed decreases and the opening size increases), the peak sound absorption value of the duct silencing device shifts towards higher frequencies. This variation is consistent with the variation of the current resonant frequency with the opening parameters in the Helmholtz resonant frequency formula. This duct silencing device can achieve a frequency adjustment range of 600Hz to 950Hz, and the sound absorption coefficient corresponding to the peak sound absorption value is greater than 0.8, with a sound absorption half-bandwidth exceeding 100Hz, fully demonstrating its excellent sound absorption performance.

[0057] In summary, the structure designed in this invention extends the acoustic length of the neck without occupying too much space by arranging two Helmholtz resonators in an anti-symmetrical manner, thus achieving effective absorption of low-frequency noise. At the same time, the noise reduction frequency of the silencing device is controlled in real time by adjusting the size of the opening cotton knot through the shielding component. Combined with the control process of real-time frequency adjustment, the goal of real-time noise control is achieved.

[0058] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A duct noise reduction device, characterized in that, include: The muffler comprises a top cover, a bottom cover, and a shielding component. The top cover and bottom cover are respectively installed on the top and bottom of the muffler. The muffler has at least one resonant cavity structure inside. Each resonant cavity structure includes a resonant cavity and a sound-absorbing port. The sound-absorbing port is opened on the side wall of the muffler and communicates with the resonant cavity along the radial direction of the muffler. The top cover has an opening that communicates with the resonant cavity along the axial direction of the muffler. The shielding component is rotatably installed on the top cover and blocks the opening to adjust the size of the opening.

2. The duct silencing device according to claim 1, characterized in that, Each of the resonant cavity structures also includes a neck. The resonant cavity structure is formed by a pair of Helmholtz resonators. The first Helmholtz resonator takes the sound-absorbing port as its entrance and surrounds the outer periphery of the second Helmholtz resonator. The inner side of the second Helmholtz resonator surrounds and forms the resonant cavity. The path between the entrance of the first Helmholtz resonator and the entrance of the second Helmholtz resonator is defined by the inner side of the first Helmholtz resonator and the outer side of the second Helmholtz resonator, which defines the neck.

3. The duct silencing device according to claim 2, characterized in that, The inlet of the second Helmholtz resonator is arranged in the opposite direction to the inlet of the first Helmholtz resonator along the radial direction of the silencer.

4. The duct silencing device according to claim 3, characterized in that, Both the first Helmholtz resonator and the second Helmholtz resonator have a fan-shaped structure. The entrance of the first Helmholtz resonator is located at the arc of the fan-shaped structure, and the entrance of the second Helmholtz resonator is located at the central corner of the fan-shaped structure.

5. The duct silencing device according to claim 1, characterized in that, The sound-absorbing port has a slit structure and extends from the bottom to the top of the muffler along its axial direction.

6. The duct silencing device according to any one of claims 1-5, characterized in that, The resonant cavity structure is provided in multiple ways, and the multiple resonant cavity structures are evenly distributed along the circumference of the muffler.

7. The duct silencing device according to claim 6, characterized in that, It also includes a driving component. The top cover has multiple openings that are respectively connected to the multiple resonant cavities. Each opening extends along the circumference of the muffler to form an arc-shaped opening. The shielding component includes a rotating shaft and multiple shielding blades. The multiple shielding blades are respectively fixedly connected to the rotating shaft along the circumference of the rotating shaft. Each shielding blade shields one of the openings. The rotating shaft passes through the center of the top cover, the muffler and the bottom cover in sequence and is connected to the driving component.

8. An air conditioner, characterized in that, The device includes an air duct and an air duct silencing device, wherein the air duct silencing device is the air duct silencing device according to any one of claims 1-7, the air duct has a sound outlet, and the air duct silencing device is located outside the air duct with its sound absorption port aligned with the sound outlet.

9. A control method for an air conditioner, characterized in that, Applied to the air conditioner of claim 8, the method includes: Get the current fan speed setting of the air conditioner; The current operating windshield drives the shielding component to rotate to the target opening position corresponding to the current operating windshield, wherein each operating windshield corresponds one-to-one with multiple different opening positions of the shielding component.

10. The method according to claim 9, characterized in that, The method further includes: Adjust the operating windshield to the lowest operating windshield and drive the blocking member to rotate until it completely blocks the opening; Acquire the time-domain noise signal in the air duct and convert the time-domain noise signal into an octave band spectrum, and record the center frequency of the highest frequency band of the noise value in the octave band spectrum; The center frequency is used as the reference resonant frequency, and the size parameters of the resonant cavity structure are determined according to the Helmholtz resonant frequency formula based on the reference resonant frequency. Adjust the operating windshield to the next operating windshield, obtain the current center frequency of the air duct and the current resonance frequency of the resonant cavity structure, and drive the shielding member to rotate and adjust the opening size so that the current center frequency is consistent with the current resonance frequency, and mark the current opening position of the shielding member; Continue adjusting the next operating windshield and marking the corresponding opening position until all operating windshields are marked.

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