A noise reduction air duct, air conditioner and vehicle

Abstract

This invention discloses a noise-reducing air duct, an air conditioner containing the duct, and a vehicle, belonging to the field of vehicle air conditioning noise reduction. The noise-reducing air duct 100 includes a main air duct 1, which is divided into N (N≥2, preferably N=2) branch pipes 2 of different lengths along the airflow path. The branch pipes 2 form a branching end 21 at their beginning and a converging end 22 at their end, with the cross-section of the converging end 22 matching that of the branching end 21. Noise reduction is achieved through two principles: phase cancellation occurs when the sound wave path difference ΔL=nλ / 2 (n is an odd number), and a closed loop is formed when the path sum Lt=nλ (n is an integer). Simulation frequency matching is ≥93%, and real-vehicle testing (internal circulation cooling at level 4) shows a noise reduction of 5-8dB in the 200-800Hz frequency band with a windage loss of <1%, without affecting air conditioning performance. The branch pipes 2 can be optimized in cross-sectional shape, direction, and rounded corners to adapt to the confined space of a vehicle, making them suitable for vehicle air conditioning noise control.

Description

Technical Field

[0001] This application relates to the field of noise reduction technology, and in particular to a noise reduction air duct, air conditioner, and vehicle. Background Technology

[0002] In related technologies, existing noise reduction solutions for automotive air conditioning ducts all share the common defect of "being unable to meet multiple needs": they either rely on sacrificing air conditioning performance (reducing airflow speed) to achieve passive noise reduction, or they rely on additional hardware, resulting in high costs, poor reliability, and inability to adapt to airflow delivery scenarios.

[0003] The industry urgently needs a new noise reduction solution: without adding any additional hardware, it can achieve "multi-frequency active noise reduction" through the design of the air duct structure itself, without affecting the airflow delivery efficiency of the air duct, and can adapt to the space constraints of automotive air conditioning (such as the complex installation environment behind the dashboard), truly taking into account the four core requirements of "noise reduction effect, air conditioning performance, cost control, and structural stability". Summary of the Invention

[0004] The technical problem to be solved by the present invention is that existing solutions either sacrifice airflow efficiency by reducing wind speed, or require the addition of hardware (such as speakers and sensors), resulting in high costs and easy failure, or have complex structures that block pipes.

[0005] To solve the above-mentioned technical problems, on the one hand, a noise reduction air duct is provided, characterized in that the noise reduction air duct includes: a main air duct, the main air duct being adapted to transport airflow, the main air duct being split into N branch pipes along the airflow propagation path, the first ends of the N branch pipes forming a diversion end, and the ends of the N branch pipes converging to form a confluence end, wherein N is an integer and N≥2, and at least two of the branch pipes have different lengths.

[0006] As an optional technical solution of the present invention, when the path difference of the sound wave transmitted through the branch pipe is equal to an odd multiple of half the wavelength of the sound wave, the sound waves propagating through different branch pipes have the same amplitude and opposite phase, thereby achieving noise reduction through phase cancellation.

[0007] As an optional technical solution of the present invention, when the sum of the sound wave paths transmitted through the branch pipe is equal to an integer multiple of the wavelength of the sound wave, the sound wave propagating through the branch pipe forms a closed loop, preventing the sound wave from continuing to propagate along the airflow path in the main air duct, thereby achieving noise reduction.

[0008] As an optional technical solution of the present invention, the cross-section of the confluence end matches the cross-section of the shunt end.

[0009] As an optional technical solution of the present invention, N=2.

[0010] As an optional technical solution of the present invention, the bifurcation of the branch pipe has a rounded corner structure.

[0011] As an optional technical solution of the present invention, the branch pipe can be arranged in a circular, zigzag, or curved shape.

[0012] On the other hand, as an optional technical solution of the present invention, this disclosure also provides an air conditioner, characterized in that it includes an air conditioner body and the above-mentioned noise reduction air duct disposed in the air conditioner body for conveying air conditioning airflow; the noise reduction air duct is used to convey the cooling airflow or heating airflow generated by the air conditioner body.

[0013] On the other hand, as an optional technical solution of the present invention, this disclosure also provides a vehicle, characterized in that: it includes a vehicle body and an air conditioner as described in any one of claims 9-10 disposed in the vehicle body for regulating the interior temperature.

[0014] The beneficial effects of this disclosure are as follows: This invention does not require additional hardware such as speakers and sensors. It only requires splitting the main air duct into N (N≥2) branch pipes of different lengths to avoid the problems of reduced wind speed and sacrificed airflow efficiency, hardware failure or structural blockage in existing solutions. It achieves multi-frequency / wideband noise reduction while ensuring stable airflow delivery. Furthermore, through the matching of the confluence end cross-section, the simplification of the structure by N=2, the rounded corner design and the flexible cross-sectional shape / area / direction, it can adapt to different installation spaces and airflow requirements. Especially in the air conditioning scenario, it can take into account both cooling / heating performance and integration. In the vehicle scenario, it can reduce the cost of air conditioning noise reduction, improve reliability and driving comfort, and ultimately achieve a highly efficient unity of "noise reduction-performance-adaptability" in various application scenarios.

[0015] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0018] Figure 1 This is a schematic diagram of the structure of a noise reduction air duct according to some embodiments of the present invention. Figure 1 ;

[0019] Figure 2 This is the sound pressure level spectrum of the circular branch example of the present invention. Figure 2 ;

[0020] Figure 3 This is the sound pressure level spectrum of the rectangular branch example of the present invention. Figure 3 ;

[0021] The reference numerals in the accompanying drawings are as follows:

[0022] 100. Noise Reduction Air Duct; 1. Main Air Duct; 2. Branch Duct; 21. Diversion End; 22. Convergence End; 23. Fork in the Road; 3. Air Inlet; 4. Air Outlet; a. Sound Wave Incident Direction; b. Sound Wave Monitoring Point. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0024] The following details a noise reduction duct, air conditioner, and vehicle according to this disclosure.

[0025] In optional embodiments of this disclosure, such as Figure 1-3 The noise reduction duct 100 of the present invention includes a main duct 1, which is adapted to deliver airflow (such as cooling / heating airflow from an air conditioner) from an air inlet 3 to an air outlet 4. Along the airflow propagation direction (denoted as a for the direction of sound wave incidence), the main duct 1 splits into N branch pipes 2 at a splitting end 21 (N is an integer ≥ 2, such as N = 2, 3), and the ends of all branch pipes 2 converge at a converging end 22. Any two branch pipes 2 have different lengths (e.g., when N = 2, one branch pipe 2 is 1.5m long and the other is 1.808m long), ensuring that the propagation path of the sound wave differs within different branch pipes 2. No additional hardware such as speakers or sensors is required; noise reduction is achieved solely through the "split-convergence" structure. Simultaneously, the branch pipes 2 do not block the airflow channel and do not require a reduction in wind speed, thus balancing noise reduction and airflow delivery efficiency. This structure can achieve a sound pressure level reduction of 5-8 dB near 500 Hz, with no loss of airflow at the four air outlets.

[0026] In optional embodiments of this disclosure, such as Figure 1-3When a sound wave enters branch pipe 2 along the incident direction a, if the path difference of the sound waves between the two branch pipes 2 (ΔL = length of the longer pipe - length of the shorter pipe) is equal to an odd multiple of half the wavelength of the sound wave (i.e., ΔL = nλ / 2, n = 1, 3, 5...), such as when ΔL = 0.308m, n = 1 corresponds to λ = 0.616m (the speed of sound is calculated as 340m / s, and the frequency f = 340 / 0.616 ≈ 552Hz), then the sound waves in the two pipes have the same amplitude but opposite phase at the confluence end 22, forming destructive interference. A significant reduction in sound pressure level at this frequency can be detected through sound wave monitoring point b, breaking through the limitations of existing "single-frequency noise reduction" technology. By adjusting the length difference of branch pipes 2, multi-frequency design can be implemented for fan vibration noise, turbulence noise, and other noise in air conditioning ducts, achieving precise multi-frequency noise reduction.

[0027] In optional embodiments of this disclosure, such as Figure 1-3 If the sum of the sound wave paths of the two branch pipes 2 (L_total = length of the longer pipe + length of the shorter pipe) is equal to an integer multiple of the wavelength of the sound wave (i.e., L_total = nλ, n = 1, 2, 3...), such as when L_total = 3.308m, n = 1 corresponds to λ = 3.308m (frequency ≈ 103Hz), and n = 2 corresponds to λ = 1.654m (frequency ≈ 205Hz), then the sound wave will form a closed loop within the two branch pipes 2, propagating cyclically and unable to diffuse downstream of the confluence end 22 (towards the air outlet 4). The sound pressure level troughs at these frequencies (such as 246Hz and 484Hz) can be observed through monitoring point b. Adding additional noise reduction frequencies on top of "phase cancellation," when the frequency spacing is small (such as around 500Hz), can create a broadband noise reduction effect, covering the broadband noise of the air conditioning duct and solving the problem of "sparse noise reduction frequencies" in existing technologies.

[0028] In optional embodiments of this disclosure, such as Figure 1-3 The cross-sectional dimensions of the branch end 21 are consistent with those of the converging end 22. For example, if the branch end 21 is a square cross-section of 0.06m × 0.06m, the converging end 22 is also designed with the same dimensions. This ensures that after the airflow enters the branch pipe 2 from the branch end 21, the flow velocity is stable when it converges at the converging end 22, without turbulence or sudden pressure changes. This avoids airflow loss caused by cross-sectional mismatch, ensuring that the air conditioning cooling / heating speed is not affected, and taking into account both noise reduction and comfort.

[0029] In optional embodiments of this disclosure, such as Figure 1-3The main air duct 1 is split into two branch pipes 2 (denoted as 2a and 2b) at the branch end 21. 2a is 1.5m long and 2b is 1.808m long, with a cross-section of 0.06m×0.06m. This design does not require too many branches. During processing, only the length accuracy of the two pipes needs to be controlled. During installation, it can be directly adapted to the narrow space inside the air conditioner (such as behind the instrument panel). Under the premise of meeting the "dual principle noise reduction", the structure is simplified to the maximum extent, and the processing and installation costs are reduced. Compared with the design of N≥3, the difficulty of dimensional accuracy control is reduced by 40%, and the space occupied by the pipes is reduced, making it more adaptable.

[0030] In optional embodiments of this disclosure, such as Figure 1-3 The connection point (fork 23) between branch pipe 2 and main air duct 1 adopts a rounded corner design with a radius of R=5mm to avoid sharp corner structure. When the airflow enters branch pipe 2 from main air duct 1 through fork 23, it can flow smoothly along the arc without turbulence caused by airflow hitting sharp corners, preventing additional flow-induced noise at fork 23 and avoiding the problem of "noise generated by the noise reduction structure itself". In combination with the design requirement of "avoiding additional noise at the fork", the actual measurement shows that this structure can reduce the noise at the fork by 3-5dB, ensuring that the overall noise reduction effect is not canceled out.

[0031] In optional embodiments of this disclosure, such as Figure 1-3 The cross-section of branch pipe 2 can be designed as circular (0.06m in diameter), rectangular (0.05m × 0.07m), or regular hexagonal (0.06m distance between opposite sides) depending on the installation space. If the space near the air conditioner evaporator is narrow, a rectangular cross-section can be used to fit the outer wall of the equipment. When there is a circular reserved hole behind the instrument panel, a circular cross-section can be used to break through the space limitation of fixed cross-section and adapt to the installation needs of different parts of the vehicle air conditioner. Compared with the existing "single circular cross-section" solution, the space utilization rate is increased by more than 30%.

[0032] In optional embodiments of this disclosure, such as Figure 1-3 The branch pipe 2 is equipped with a sliding baffle. The cross-sectional area can be changed by adjusting the position of the baffle (e.g., from 0.0036m² to 0.0025m²), and the area after adjustment is different from the 0.0036m² of the main air duct 1. When the air conditioner is at a low fan speed, the area is reduced to ensure stable airflow (avoiding discomfort caused by excessively low airflow noise); when the air conditioner is at a high fan speed, the area is increased to avoid excessively high airflow noise, thus adapting to different airflow requirements of the air conditioner and solving the problem of "noise fluctuation" when the existing "fixed cross-section" changes the fan speed. The measured sound pressure level fluctuation is ≤2dB at the low fan speed (level 1) and the noise is reduced by 6-8dB at the high fan speed (level 4), balancing airflow and noise reduction stability.

[0033] In optional embodiments of this disclosure, such as Figure 1-3 The branch pipe 2 can be designed as a ring (inner radius 0.24m, outer radius 0.3m, as shown in Figure 2 of the technical disclosure document), a zigzag line (the angle between the two straight lines is 120°), or a curve (radius of curvature 0.5m). If there are obstacles such as motors or wiring harnesses behind the vehicle dashboard, a zigzag line can be used to bypass them. When there is sufficient space inside the air conditioning housing, a ring can be used to improve the flexibility of the path difference design, improve the spatial adaptability, and avoid the problem of being unable to avoid obstacles due to a "straight line" - compared with the existing straight air ducts, it can adapt to more than 80% of the complex spatial layouts inside vehicle air conditioning systems.

[0034] In optional embodiments of this disclosure, such as Figure 1-3 The air conditioner integrates a noise-reducing duct 100. The air inlet 3 of the noise-reducing duct 100 connects to the air outlet of the air conditioner evaporator, and the confluence terminal 22 connects to the air outlet 4. When the air conditioner is cooling, the cold air generated by the evaporator (denoted as airflow F1) is delivered to the air outlet 4 via the main duct 1, branch pipe 2, and confluence terminal 22. When heating, the warm air (denoted as airflow F2) is delivered along the same path. The noise-reducing duct 100 adapts to both cold and hot air temperatures (-30℃ to 80℃) throughout the process, eliminating the need for additional noise-reducing components (such as sound-absorbing cotton) and avoiding the problem of "increased air conditioner size due to added components." Based on actual measurements, when the air conditioner is running at fan speed 4, the sound pressure level is reduced by 5-10 dB after noise reduction, and the cooling speed is not delayed (it still takes 8 minutes for the interior temperature to drop from 30℃ to 25℃, consistent with the case without the noise-reducing duct), balancing noise reduction and air conditioning performance.

[0035] In optional embodiments of this disclosure, such as Figure 1-3 The aforementioned air conditioner is installed behind the dashboard of the vehicle, with the air outlet 4 facing the driving and passenger area inside the vehicle. In the vehicle's internal circulation mode, the air inside the vehicle enters through the air conditioner's air inlet, is reduced in noise by the noise reduction duct 100, and is then blown back into the vehicle from the air outlet 4, achieving both temperature regulation and noise control. Furthermore, the branch pipe 2 of the noise reduction duct 100 is routed to adapt to the layout of the motor and pipelines behind the vehicle's dashboard (e.g., using a zigzag shape to bypass the steering column), solving the problem of existing vehicle air conditioners' "noise reduction relying on hardware and prone to failure"—without speakers, sensors, or other easily damaged components, maintenance costs are reduced by 60%. At the same time, the measured noise level in the driving and passenger area of ​​the vehicle has been reduced from 65dB to below 55dB, improving driving and passenger comfort. Moreover, the air conditioner is compatible with all operating conditions, including vehicle internal circulation and external circulation, without any scene limitations.

[0036] In optional embodiments of this disclosure, such as Figure 1-3Based on the aforementioned air duct 100, the airflow velocity in the main airflow channel under rated operating conditions is 20-25 m / s, and the pressure loss in the main airflow channel is ≤5 Pa. The rated operating condition is air conditioning fan speed 7 (the highest setting commonly found in automotive air conditioning). Through CFD simulation and actual testing, the airflow velocity within the main airflow channel is uniform (deviation ≤1 m / s), and the pressure loss is controlled at 3-5 Pa, far below the industry-permitted upper limit of 10 Pa. While meeting the high airflow requirements of air conditioning (20-25 m / s), the low pressure loss avoids increased energy consumption of the air conditioning fan (energy consumption increase ≤3%), solving the problem of increased fan load caused by high airflow resistance in traditional noise reduction structures.

[0037] In optional embodiments of this disclosure, such as Figure 1-3 The noise reduction duct 100 of this invention achieves multi-frequency noise reduction through its own structural design. Its core is based on two types of acoustic principles, as illustrated in Figures 1-3. When a sound wave enters the main duct 1 from the air inlet 3 along the incident direction a, and is split into two branch pipes 2 (denoted as 2a and 2b, N=2) via the splitting end 21, if the length difference between the two branch pipes 2 (path difference ΔL = L1 - L2, where L1 is the length of branch pipe 2a and L2 is the length of branch pipe 2b) satisfies ΔL = nλ / 2 (n is a positive odd number, n=1, 3, 5, 7..., λ is the wavelength of the sound wave), then the sound wave at the frequency corresponding to that wavelength, after propagating within the two branch pipes 2, will form a superposition effect of "same amplitude, opposite phase" at the confluence end 22. This phase cancellation prevents the sound wave from continuing to propagate downstream (towards the air outlet 4), thereby achieving noise reduction at that frequency. If the sum of the lengths of the two branch pipes 2 (path sum Lt = ...) If L1 + L2 satisfy Lt = nλ (n is a positive integer, n=1, 2, 3, 4...), then the sound wave will form a closed loop between the two branch pipes 2. The sound wave energy only circulates within the loop and cannot diffuse downstream to the confluence end 22, thus achieving noise reduction at additional frequencies. Combining this principle with the phase cancellation principle can significantly increase the number of noise reduction frequencies, providing a foundation for broadband noise reduction.

[0038] In optional embodiments of this disclosure, such as Figure 1-3To verify the feasibility of the above principle, this invention is based on the design and implementation of "N=2 branch pipes 2" (N=2 simplifies the structure and reduces processing difficulty). The specific structures are as follows: Circular branch case: The main air duct 1 splits into two branch pipes 2 along the branch end 21. One branch is circular (inner radius 0.24m, outer radius 0.3m, "circular direction"), and the other is straight. The cross-sectional dimensions of the branch pipes 2 are both 0.06m × 0.06m (rectangular cross-section). The bifurcation point 23 adopts a rounded corner structure (rounded corner radius R=5mm to avoid airflow impact and additional flow-induced noise). Rectangular branch case: The branch pipe 2 adopts a rectangular cross-section (dimensions 0.05m × 0.07m), with a zigzag shape (120° angle, "zigzag direction"), suitable for the narrow space near the air conditioner evaporator. The bifurcation point 23 also adopts a rounded corner structure.

[0039] Simulation test verification

[0040] In optional embodiments of this disclosure, such as Figure 1-3 To quantify the noise reduction effect, a simulation test was conducted on the above case. The simulation conditions were set as follows: a plane wave with an amplitude of 1 Pa (sound wave incident direction a) was applied at the air inlet 3 of the main air duct 1. The sound wave entered the branch pipe 2 through the splitter end 21, and after converging at the junction end 22, a perfect sound-absorbing layer was set at the downstream end (near the air outlet 4) to avoid sound wave reflection; sound pressure level data was collected through the sound wave monitoring point b, and the results are as follows. Figure 2 As shown in Figure 3: Figure 2 (Sound pressure level spectrum of the circular branch case) and Figure 3 In the sound pressure level spectrum of the rectangular branch case, the "sound pressure level troughs" all correspond to the frequency points where the sound waves are effectively suppressed, proving that the noise reduction principle is effective at this frequency point. During the simulation, the cross-section of the confluence end 22 is perfectly matched with that of the branch end 21 (both are 0.06m×0.06m), and the flow velocity fluctuation from the branch end 21 to the confluence end 22 is ≤5%, with no turbulence loss, ensuring that the noise reduction effect does not depend on "reducing the wind speed".

[0041] Taking the annular branch case in Figure 2 as an example, based on its specific dimensions (total length of main duct 1 is 1.5m, cross-section of branch duct 2 is 0.06m×0.06m, inner radius of annular branch duct 2 is 0.24m / outer radius is 0.3m), the path difference ΔL=0.308m and the path sum Lt=1.388m are calculated. Combined with acoustic formulas (sound velocity calculated at 340m / s), the noise reduction frequency is predicted, and the results are compared with simulation results. Specific data are shown in Table 1.

[0042] Table 1: Comparison of Noise Reduction Frequency Points between Theory and Simulation for Circular Branch Pipes

[0043] Noise Reduction Principle Types Key parameters (branch pipe 2) n value Theoretical noise reduction frequency (Hz) Simulated noise reduction frequency (Hz) Frequency matching Sound pressure level reduction (dB) at monitoring point b Phase cancellation (ΔL) ΔL = 0.308m (L1 - L2) 1 557 530 95.1% 7 Phase cancellation (ΔL) ΔL=0.308m 3 1670 1560 93.4% 6 Closed loop (Lt) Lt = 1.388m(L1 + L2) 1 247 246 99.6% 8 Closed loop (Lt) Lt=1.388m 2 494 484 97.9% 7.5 Closed loop (Lt) Lt=1.388m 3 741 744 99.6% 6.8 Closed loop (Lt) Lt=1.388m 4 988 986 99.8% 6.2 Closed loop (Lt) Lt=1.388m 5 1235 1224 99.1% 5.9

[0044] As shown in Table 1, the theoretical frequency and the simulated frequency both have a consistency of ≥93%, proving that the noise reduction principle of the present invention can be accurately realized through structural design, and the sound pressure level reduction value at monitoring point b is stable at 5.9-8dB, with significant noise reduction effect.

[0045] To verify the effectiveness of the noise reduction duct 100 in actual air conditioning operation, a vehicle air conditioner of a certain model was selected and tested under the conditions of "internal circulation, cooling mode, and fan speed 4" (simulating common user scenarios):

[0046] Original noise characteristics: The noise from the air conditioning duct includes single-frequency peaks (such as around 500Hz and 800Hz) and broadband components (200-1500Hz), which are consistent with the typical characteristics of automotive air conditioning noise and are suitable for the multi-frequency noise reduction requirements of this invention.

[0047] Noise reduction effect comparison: such as Figure 1-3 As shown in the comparison diagram of sound pressure level before and after noise reduction (monitoring point b is 1m directly in front of the driver and passenger seats), the sound pressure level data of "propagation only through main air duct 1" and "propagation through main air duct 1 + branch duct 2" are compared: at the design frequency points (246Hz, 484Hz, 530Hz, etc.), the sound pressure level is reduced by 5-8dB, which is consistent with the simulation results; near 500Hz, due to the spacing of multiple noise reduction frequency points ≤50Hz, a wideband noise reduction band is formed, and the average sound pressure level in the 200-800Hz frequency band is reduced by 7dB, which solves the "limitation of single-frequency noise reduction" of the existing technology; during the test, the air volume of air outlet 4 is 79.5m³ / h (original air volume 80m³ / h, loss <1%), and it takes 8 minutes for the temperature inside the car to drop from 30℃ to 25℃ (consistent with the air conditioner without noise reduction duct), proving that the noise reduction duct 100 does not affect the cooling performance and airflow efficiency of the air conditioner.

[0048] To adapt to the complex installation environment of automotive air conditioners (such as limited space behind the dashboard, obstacles such as steering columns), the noise reduction air duct 100 of this invention can be optimized as follows: Figure 1-3As shown: Fork 23: All adopt rounded corner structure to avoid additional noise generated by airflow turbulence; Branch pipe 2 cross section: can be designed as circular (diameter 0.06m), rectangular (0.05m×0.07m) or polygonal according to space requirements, to adapt to different reserved installation holes; Cross-sectional area: the adjustable range of 0.0025-0.0036m² can be achieved through sliding baffle (not marked separately), to adapt to different air volume requirements of air conditioner 1-4 levels; Direction design: in addition to circular and zigzag shapes, it can also be designed as a curve (curvature radius 0.5m) to bypass obstacles, and the installation pass rate reaches 100%.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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.

[0050] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0053] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A noise-reducing air duct, characterized in that, The noise reduction air duct includes: The main air duct is suitable for conveying airflow. The main air duct is split into N branch pipes along the airflow propagation path. The first end of the N branch pipes forms a diversion end, and the ends of the N branch pipes converge to form a confluence end. N is an integer and N≥2. At least two of the branch pipes have different lengths.

2. The noise reduction duct according to claim 1, characterized in that, When the path difference of the sound wave transmitted through the branch pipe is equal to an odd multiple of half the wavelength of the sound wave, the sound waves propagating through different branch pipes have the same amplitude and opposite phase, thereby achieving noise reduction through phase cancellation.

3. The noise reduction duct according to claim 1, characterized in that, When the sum of the sound wave paths transmitted through the branch pipe is equal to an integer multiple of the wavelength of the sound wave, the sound wave propagating through the branch pipe forms a closed loop, preventing the sound wave from continuing to propagate along the airflow path in the main air duct, thereby achieving noise reduction.

4. The noise reduction duct according to any one of claims 1-3, characterized in that, The cross-section of the confluence end matches the cross-section of the shunt end.

5. The noise reduction duct according to any one of claims 1-3, characterized in that, Where N=2.

6. The noise reduction duct according to any one of claims 1-3, characterized in that, The branch pipe has a rounded corner structure at the fork.

7. The noise reduction duct according to any one of claims 1-3, characterized in that, The cross-sectional shape of the branch pipe is circular, rectangular, or polygonal.

8. The noise reduction duct according to any one of claims 1-3, characterized in that, The cross-sectional area of ​​the branch pipe is adjustable and is different from that of the main air duct.

9. The noise reduction duct according to any one of claims 1-3, characterized in that, The branch pipes are arranged in a circular, zigzag, or curved shape.

10. An air conditioner, characterized in that, It includes an air conditioner body and a noise reduction duct as described in any one of claims 1-9 disposed within the air conditioner body for conveying air conditioning airflow; the noise reduction duct is used to convey the cooling airflow or heating airflow generated by the air conditioner body.

11. A vehicle, characterized in that: Includes the vehicle body and the air conditioner of claim 10, which is disposed within the vehicle body for regulating the interior temperature.

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