A noise reduction device for the front end of an air duct and a cooling fan

Abstract

The present invention provides a sound-absorbing and noise-reducing device and a cooling fan for use at the front end of an air duct, which are used in the field of computer noise reduction technology. A sound-absorbing support shell and a resonant sound-reducing inner shell are nested and installed with each other, forming a cavity interlayer for noise reduction between the sound-absorbing support shell and the resonant sound-reducing inner shell. The cross-section of the resonant sound-reducing inner shell is U-shaped, and both the sound-absorbing support shell and the resonant sound-reducing inner shell are annular. When air flows through the inner ring of the annular ring, sound repeatedly impacts the U-shaped annular groove of the resonant sound-reducing inner shell, converting the sound energy into energy of the resonant sound-reducing inner shell, thereby reducing noise. The surface of the resonant sound-reducing inner shell is provided with an array of sound holes, through which a portion of the sound enters the cavity interlayer between the sound-absorbing support shell and the resonant sound-reducing inner shell, where it is repeatedly reflected, ultimately reducing the sound. The characteristics of the metal microporous plate itself and the design of the sound-absorbing support shell and the resonant sound-reducing inner shell jointly achieve the effect of reducing sound, avoiding increasing the aerodynamic noise at the air duct opening while maximizing the sound absorption and noise reduction effect.

Description

Technical Field

[0001] The present invention relates to the field of computer noise reduction technology, and further relates to a noise reduction device for the front end of an air duct. In addition, the present invention also relates to a heat dissipation fan. Background Art

[0002] Servers primarily utilize air cooling for internal heat dissipation, with fans drawing air into the server. Server fans are constantly increasing in speed, generating significant aerodynamic noise during operation. Simultaneously, the capacity of storage devices like mechanical hard drives is increasing, and these devices are becoming increasingly sensitive to noise and vibration. The combined effects of increased fan noise and the storage devices' high vibration requirements can significantly degrade the read and write performance of mechanical hard drives. Furthermore, the sound quality at the front of the machine can also deteriorate.

[0003] Due to the space limitations and complex flow fields within the server, conventional silencers or noise-reducing structures and materials are difficult to directly incorporate into the server's noise reduction design. Current solutions are relatively simple, primarily consisting of honeycomb meshes and sound-absorbing cotton pasted around the perimeter. Honeycomb meshes primarily reduce aerodynamic noise by stabilizing the flow, but the noise reduction effect is very limited. Sound-absorbing cotton is effective for absorbing and reducing noise, but to ensure sufficient flow channels, it can only be pasted on the walls surrounding the server, significantly reducing its effectiveness. The noise reduction effect on the hard drive area in front of the fan is uneven, failing to achieve the desired effect. Current noise control technologies lack revolutionary innovations in sound absorption, sound insulation, and noise reduction, and the performance levels of sound-absorbing and noise-reducing materials vary slightly.

[0004] For those skilled in the art, how to more effectively reduce the noise of the cooling fan is a technical problem that needs to be solved. Summary of the Invention

[0005] The present invention provides a noise reduction device for the front end of an air duct, which can reduce the noise at the fan air inlet and achieve better noise reduction effects through a combination of multiple means. The specific scheme is as follows:

[0006] A sound-absorbing and noise-reducing device for the front end of an air duct comprises a sound-absorbing support outer shell and a resonant sound-reducing inner shell. The sound-absorbing support outer shell and the resonant sound-reducing inner shell are nested with each other to form a cavity sandwich for sound reduction. The sound-absorbing support outer shell and the resonant sound-reducing inner shell are installed together in front of a fan.

[0007] The sound-absorbing support outer shell and the resonant sound-absorbing inner shell are both annular, and the resonant sound-absorbing inner shell includes a resonant front wall, a resonant bottom wall, and a resonant rear wall. The cross-section formed by the resonant front wall, the resonant bottom wall, and the resonant rear wall is in the shape of a U-shaped groove;

[0008] The resonant sound-absorbing inner shell is a metal microporous plate, and sound holes are arranged through the surface of the plate in an array.

[0009] The present invention utilizes a dual-layer structure consisting of a sound-absorbing support outer shell and a resonant muffler inner shell. This design reduces noise through continuous reflection within the inner cavity of the resonant muffler inner shell. The noise also causes the thin metal shell to vibrate, thereby reducing noise. Furthermore, noise enters the cavity between the sound-absorbing support outer shell and the resonant muffler inner shell through the sound holes, where it is also attenuated. These structural features work together to achieve aerodynamic noise reduction, effectively reducing the aerodynamic noise generated by the fan.

[0010] Optionally, the sound-absorbing support shell and the resonance sound-absorbing inner shell are both thin shell structures, and the sound-absorbing support shell includes a sound-absorbing front wall, a sound-absorbing bottom wall, and a sound-absorbing rear wall.

[0011] When the sound-absorbing support outer shell and the resonant sound-absorbing inner shell are assembled with each other, the sound-absorbing front wall and the resonant front wall form a flat sandwich, the sound-absorbing bottom wall and the resonant bottom wall form a flat cylindrical sandwich, and the sound-absorbing rear wall and the resonant rear wall form a flat sandwich. The three sandwiches are not completely independent and are interconnected.

[0012] Optionally, a windward baffle is provided on the inner edge of the resonant front wall, and the inner diameter of the windward baffle is smaller than the inner diameter of the sound-absorbing rear wall.

[0013] The inner circle diameter of the windward baffle is smaller, and the windward baffle at the air inlet of the silencer structure cuts into the actual air duct. Through the physical structure of the windward baffle, the noise transmitted from the fan to the front end of the fan, that is, the noise transmitted against the direction of the airflow, is specifically weakened.

[0014] Optionally, the inner diameter of the windward baffle is 80%-95% of the inner diameter of the sound-absorbing rear wall.

[0015] The ratio of the inner diameter of the windward baffle is determined according to the fluid flow rate. The higher the flow rate, the larger the inlet diameter is, and the lower the flow rate, the smaller the inlet diameter is.

[0016] Optionally, the windward deflector is inclined inward from the outer edge to the inner edge.

[0017] The entire windward baffle forms a frustum-shaped surface, which is similar to the shape of a trumpet mouth. The windward baffle guides and converges the airflow, making it flow in more smoothly.

[0018] Optionally, the cross-section of the windward side of the windward baffle is streamlined, and the cross-section of the leeward side of the windward baffle is linear.

[0019] The windward baffle has two functions. One is to make the airflow flow more smoothly through its inclined design. The other is to block and weaken the noise transmitted in the reverse direction through the wall near the inner circle of the windward baffle.

[0020] Optionally, the inclination angle of the leeward side section of the windward baffle is 10 degrees to 30 degrees.

[0021] By rationally arranging the inclination angle of the windward baffle, it is possible to satisfy the function of guiding the airflow and also to achieve the function of blocking and weakening the reverse noise.

[0022] Optionally, the windward side of the outer edge of the windward baffle is aligned with the windward side of the inner edge of the sound-absorbing support shell.

[0023] No step structure is formed between the sound-absorbing support shell and the windward baffle, so the airflow can be guided more smoothly and flow along the guiding direction of the windward baffle.

[0024] Optionally, an inner layer of sound-absorbing cotton is provided in the cavity sandwich between the sound-absorbing support outer shell and the resonance sound-absorbing inner shell.

[0025] Resonance sound absorption is achieved by forming a grooved ring structure cavity structure through the resonance sound-absorbing inner shell, which is mainly used to weaken medium and low frequency noise. The inner layer of sound-absorbing cotton is mainly used to weaken high frequency noise. Noise absorption of different frequencies such as high frequency, medium frequency and low frequency is achieved through different methods.

[0026] Optionally, an annular sound-absorbing cotton is provided on the inner surface of the sound-absorbing rear wall.

[0027] Annular sound-absorbing cotton can absorb noise and improve the absorption and weakening effect of noise.

[0028] Optionally, the cross-section of the annular sound-absorbing cotton is triangular, and the inclination angle of the surface facing the inner circle is greater than the inclination angle of the surface facing the outer circle.

[0029] The asymmetric annular sound-absorbing cotton is steeper on the side close to the airflow, and the airflow is less likely to form a dead corner; the side away from the airflow is flatter, and the flat surface area is larger. The sound is reflected to the annular sound-absorbing cotton many times and absorbed by the annular sound-absorbing cotton, reducing noise escape.

[0030] Optionally, an annular groove for clamping the annular sound-absorbing cotton is provided on the inner surface of the sound-absorbing rear wall.

[0031] The annular sound-absorbing cotton can be embedded in the annular groove provided on the inner surface of the sound-absorbing rear wall, so that the annular sound-absorbing cotton can be better positioned through the annular groove, thereby enhancing the stability of the annular sound-absorbing cotton.

[0032] Optionally, the area of ​​the sound hole provided in the resonance sound-absorbing inner shell is 20%-30% of the overall area of ​​the resonance sound-absorbing inner shell.

[0033] By properly arranging the number and size of the openings, noise can be better transmitted through the sound holes into the cavity between the sound-absorbing support shell and the resonant sound-absorbing inner shell. The distribution of the sound holes in the resonant sound-absorbing inner shell is not limited, but a centrally symmetrical arrangement is generally adopted.

[0034] The present invention also provides a heat dissipation fan, comprising any of the above-mentioned silencing and noise reduction devices for the front end of the air duct.

[0035] The present invention provides a sound attenuation and noise reduction device for the front end of an air duct, which is installed in front of a fan. A sound-absorbing support shell and a resonance sound-absorbing inner shell are nested and installed with each other, and a cavity interlayer for sound insulation is formed between the sound-absorbing support shell and the resonance sound-absorbing inner shell; the resonance sound-absorbing inner shell includes a resonance front wall surface, a resonance bottom wall surface, and a resonance rear wall surface, and the cross-section formed by the resonance sound-absorbing support shell and the resonance sound-absorbing inner shell is in the shape of a U-shaped groove, and the sound-absorbing support shell and the resonance sound-absorbing inner shell are both in the shape of a circular ring, and the resonance sound-absorbing inner shell is made of a metal microporous plate. When airflow passes through the inner ring of the circular ring, sound repeatedly impacts the U-shaped ring groove of the resonance sound-absorbing inner shell, and the energy of the sound is converted into the energy of the resonance sound-absorbing inner shell, so that the noise is reduced; the surface of the resonance sound-absorbing inner shell is provided with sound holes in an array, and a part of the sound enters the cavity interlayer between the sound-absorbing support shell and the resonance sound-absorbing inner shell through the sound holes, and is repeatedly reflected in the cavity interlayer, so that the sound is finally reduced. The present invention leverages the inherent properties of the metal microporous plate, along with the design of the sound-absorbing support outer shell and the resonant sound-absorbing inner shell, to reduce sound, effectively preventing increased aerodynamic noise at the air duct opening while maximizing the sound absorption and noise reduction effect. The cooling fan provided by the present invention can achieve the same technical effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is a schematic axonometric view of the windward side of the noise reduction device for the front end of an air duct according to the present invention;

[0038] Figure 2 This is a schematic diagram of the leeward side axonometric view of the noise reduction device for the front end of an air duct according to the present invention;

[0039] Figure 3 This is an axonometric diagram of the sound-absorbing support shell;

[0040] Figure 4 This is an axonometric diagram of the resonance-silencing inner shell;

[0041] Figure 5 Schematic diagram of the overall cross-sectional structure of the noise reduction device for the front end of the air duct of the present invention;

[0042] Figure 6 Schematic diagram of a partial cross-section of the noise reduction device for the front end of an air duct according to the present invention;

[0043] Figure 7 Schematic diagram of the cross-sectional structure of the annular sound-absorbing cotton;

[0044] Figure 8 Schematic diagram of the overall structure of the cooling fan.

[0045] The diagram includes:

[0046] Sound-absorbing supporting shell 1, sound-absorbing front wall 11, sound-absorbing bottom wall 12, sound-absorbing rear wall 13, resonant sound-absorbing inner shell 2, resonant front wall 21, resonant bottom wall 22, resonant rear wall 23, windward baffle 24, inner layer sound-absorbing cotton 3, and annular sound-absorbing cotton 4. DETAILED DESCRIPTION

[0047] The core of the present invention is to provide a noise reduction device for the front end of the air duct, which can reduce the noise at the fan air inlet.

[0048] In order to enable those skilled in the art to better understand the technical solution of the present invention, the noise reduction device for the front end of the air duct and the heat dissipation fan of the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0049] Combine Figure 1 and Figure 2 The figures shown are respectively the isometric diagrams of the noise reduction device for the front end of the air duct of the present invention in two different directions; the drawings shown in the present invention are all shown as examples of certain specific implementation methods, which does not mean that the present invention is only implemented in the scheme shown in the drawings. Figure 1 Shows the angle of the windward side, Figure 2 Shows the angle of the leeward side, with airflow flowing from the windward side to the leeward side. Figure 5 , is a schematic diagram of the flow direction of the airflow. The arrows in the figure indicate the flow direction of the airflow, and the airflow moves from the left to the right. Figure 5 The left side is the windward side, the right side is the leeward side, and the fan is installed in Figure 5 On the right side of the structure.

[0050] The present invention provides a noise reduction device for the front end of an air duct, which is installed at the front air inlet of a fan. The device includes a sound-absorbing support outer shell 1 and a resonant sound-absorbing inner shell 2. The sound-absorbing support outer shell 1 and the resonant sound-absorbing inner shell 2 are nested and installed with the sound-absorbing support outer shell 1 on the outside and the resonant sound-absorbing inner shell 2 on the inside. A cavity interlayer for sound absorption is formed between the sound-absorbing support outer shell 1 and the resonant sound-absorbing inner shell 2. In other words, there is a portion between the sound-absorbing support outer shell 1 and the resonant sound-absorbing inner shell 2 that is not in close contact, and this portion forms the cavity interlayer.

[0051] The sound-absorbing support shell 1 and the resonance sound-absorbing inner shell 2 are both annular, and a through circular hole is formed in the center of the sound-absorbing support shell 1 and the resonance sound-absorbing inner shell 2 along the axial direction. Figure 4 As shown, it is an axonometric diagram of the resonance muffler inner shell 2. The resonance muffler inner shell 2 includes a resonance front wall 21, a resonance bottom wall 22, and a resonance rear wall 23. Figure 5 The cross section formed by the resonant front wall 21, the resonant bottom wall 22, and the resonant rear wall 23 in the present invention is a U-shaped groove. The inner cavity of the entire resonant silencer inner shell 2 is a U-shaped groove-shaped annular structure, which serves as a silencing chamber.

[0052] It should be noted that the resonance front wall surface 21 and the resonance rear wall surface 23 can be set as an annular flat plate structure, that is, Figure 5 、 Figure 6 The cross section of the resonance front wall 21 and the resonance rear wall 23 is a straight line; an arc-shaped structure that bulges outward or is recessed inward can also be used, and the cross section of the resonance front wall 21 and the resonance rear wall 23 is an arc line. Figure 5 、 Figure 6 As shown, the cross section of the resonance bottom wall surface 22 is a straight line. Of course, an arc-shaped structure that bulges outward or is recessed inward can be adopted. In this case, the cross section of the resonance bottom wall surface 22 is an arc line.

[0053] The sound-absorbing support shell 1 and the resonant sound-absorbing inner shell 2 have similar appearances. Both are circular ring structures with a U-shaped groove cross-section. The sound-absorbing support shell 1 is sleeved on the outside of the resonant sound-absorbing inner shell 2. The two are connected to form a whole and are installed together at the air inlet position of the fan. The airflow first passes through the sound-absorbing and noise reduction device for the front end of the air duct provided by the present invention, and then passes through the fan.

[0054] The resonant sound-absorbing inner shell 2 of the present invention is a metal microporous plate. It is a thin metal shell structure with an array of sound holes extending through its surface. Each sound hole is formed on the surface of the shell, and the direction of penetration of each sound hole is perpendicular to the surface where it is located. The thickness of the resonant sound-absorbing inner shell 2 is related to the frequency of the noise and is determined based on the frequency range in which the noise is mainly distributed.

[0055] The resonant sound-absorbing inner shell 2 is made of a metal microporous plate, which has relatively weak structural strength. The sound-absorbing support outer shell 1 is located outside and has a stronger structural strength, providing support and reinforcement for the resonant sound-absorbing inner shell 2. The sound-absorbing support outer shell 1 is a solid structure, preventing noise leakage to the outside. The sound-absorbing support outer shell 1 and the resonant sound-absorbing inner shell 2 are fixed together to form the overall structure of the noise reduction device, which provides higher overall strength.

[0056] Combine Figure 5 When the airflow flows from the left to the right, the noise passes through the airflow channel in the center of the ring and enters the inner cavity of the resonant sound-absorbing inner shell 2. The noise is continuously reflected in the inner cavity of the resonant sound-absorbing inner shell 2, which gradually weakens the energy of the noise. Part of the noise energy is transferred to the resonant sound-absorbing inner shell 2 with a metal thin shell structure, causing the resonant sound-absorbing inner shell 2 to vibrate and absorb the energy in the noise. Since a number of small sound holes are provided on the surface of the resonant sound-absorbing inner shell 2, the sound holes can allow noise to pass through. The noise passing through the sound holes reaches the cavity interlayer formed by the sound-absorbing support outer shell 1 and the resonant sound-absorbing inner shell 2, and is continuously reflected in the cavity interlayer, and its energy is continuously weakened.

[0057] Combine Figure 4 In a specific embodiment, the sound holes on the resonant muffler inner shell 2 are distributed in an array. The sound holes opened on the resonant front wall 21 and the resonant rear wall 23 are radially distributed in a central symmetric manner. The resonant bottom wall 22 forms a plurality of rows of array-like distributions. The sound holes on the resonant front wall 21 and the sound holes on the resonant rear wall 23 correspond to each other along the axial direction. The sound holes on the resonant front wall 21 and the sound holes on the resonant rear wall 23 are arranged in rows corresponding to each other.

[0058] The present invention utilizes a dual-layer structure consisting of a sound-absorbing support outer shell 1 and a resonant sound-absorbing inner shell 2. This design reduces noise through continuous reflection within the inner cavity of the resonant sound-absorbing inner shell 2. The noise also causes the thin metal shell of the resonant sound-absorbing inner shell 2 to vibrate, thereby reducing noise. Furthermore, noise enters the cavity between the sound-absorbing support outer shell 1 and the resonant sound-absorbing inner shell 2 through the sound holes, where it is also attenuated. The synergy of these structural features achieves a significant reduction in aerodynamic noise, effectively reducing the aerodynamic noise generated by the fan.

[0059] Based on the above solution, the present invention's sound-absorbing support outer shell 1 and resonant sound-absorbing inner shell 2 both have thin-shell structures, with the sound-absorbing support outer shell 1 being a thin shell structure made of a metal microporous plate. The sound-absorbing support outer shell 1 can be a thin shell structure made of a plastic material. To ensure sufficient structural strength, the thickness of the sound-absorbing support outer shell 1 is typically greater than that of the resonant sound-absorbing inner shell 2 to prevent deformation due to airflow or impact. The sound-absorbing support outer shell 1 can also be made of metal or other materials, and the present invention does not impose specific limitations.

[0060] The resonance silencing inner shell 2 is a thin shell structure made of a metal microporous plate. However, the specific form of the sound-absorbing support outer shell 1 is not limited. For the consideration of material saving, the sound-absorbing support outer shell 1 can adopt a thin shell structure, or it can also adopt a shell-like structure with a larger thickness. The inner surface of the sound-absorbing support outer shell 1 and the outer surface of the resonance silencing inner shell 2 cooperate to form a cavity sandwich layer, and the shape of the outer surface of the sound-absorbing support outer shell 1 is not specifically limited.

[0061] The sound-absorbing support outer shell 1 includes a sound-absorbing front wall surface 11, a sound-absorbing bottom wall surface 12, and a sound-absorbing rear wall surface 13. Figure 3 、 Figure 5 Both the sound-absorbing front wall surface 11 and the sound-absorbing rear wall surface 13 are annular plate structures, and the sound-absorbing bottom wall surface 12 is an annular cylindrical structure. The outer edges of the sound-absorbing front wall surface 11 and the sound-absorbing rear wall surface 13 are respectively fixed to the two edges of the sound-absorbing bottom wall surface 12, and the three together enclose a U-shaped groove-like annular cavity.

[0062] When the sound-absorbing support outer shell 1 and the resonance silencing inner shell 2 are assembled with each other, the sound-absorbing front wall surface 11 and the resonance front wall surface 21 form a flat sandwich layer, the sound-absorbing bottom wall surface 12 and the resonance bottom wall surface 22 form a flat cylindrical sandwich layer, and the sound-absorbing rear wall surface 13 and the resonance rear wall surface 23 form a flat sandwich layer. The three sandwich layers are not completely independent of each other and are interconnected. During installation, the inner edges of the sound-absorbing front wall surface 11 and the resonance front wall surface 21 are respectively fixedly connected to maintain sealing. The inner edges of the sound-absorbing rear wall surface 13 and the resonance rear wall surface 23 are respectively fixedly connected to maintain sealing. Thus, the entire cavity sandwich layer formed by the three sandwich layers is not connected to the outside world, and the noise entering the cavity will not leak to the outside.

[0063] As shown in Figure 4 、 Figure 5 , an air-facing baffle 24 is provided at the inner ring edge of the resonance front wall surface 21. The inner ring diameter of the air-facing baffle 24 is smaller than the inner ring diameter of the sound-absorbing rear wall surface 13, that is Figure 5 in which R1 < R2, where R1 represents the inner ring diameter of the air-facing baffle 24 and R2 represents the inner ring diameter of the sound-absorbing rear wall surface 13. Since the sound-absorbing support outer shell 1 provides structural support for the resonance silencing inner shell 2, the size of the sound-absorbing support outer shell 1 is larger than the size of the resonance silencing inner shell 2, and the inner ring diameter of the sound-absorbing rear wall surface 13 is smaller than the inner ring diameter of the resonance rear wall surface 23, that is, the width of the sound-absorbing rear wall surface 13 is larger than the width of the resonance rear wall surface 23. An air-facing baffle 24 is provided at the inner ring edge of the resonance front wall surface 21, and the outer ring of the air-facing baffle 24 is fixedly connected to the inner ring of the resonance front wall surface 21. As shown in Figure 5 , the two dashed lines represent the inner ring diameter of the sound-absorbing rear wall surface 13. Since the inner ring diameter of the air-facing baffle 24 is smaller, the dashed lines pass through the air-facing baffle 24. Figure 5The arrow direction in the figure indicates the wind flow direction. The channel formed by the two dotted lines is the actual wind duct. The windward baffle 24 at the air inlet of the silencer structure cuts into the actual wind duct. The physical structure of the windward baffle 24 specifically weakens the noise transmitted from the fan to the front end of the fan, that is, Figure 5 Noise transmitted from right to left.

[0064] The windward baffle 24 and the resonant front wall 21 are integrally formed. The windward baffle 24 is a solid structure, without any openings. This ensures that the windward baffle 24 can smoothly guide the airflow, gradually converging it toward the center. Airflow enters through the central opening of the windward baffle 24 and exits through the central opening of the sound-absorbing rear wall 13.

[0065] Specifically, in the present invention, the inner diameter of the windward baffle 24 is 80%-95% of the inner diameter of the sound-absorbing rear wall 13, including two endpoint values. For example, the inner diameter of the windward baffle 24 is 80%, 85%, 90%, 95%, or other specific values ​​of the inner diameter of the sound-absorbing rear wall 13. The ratio of the inner diameter of the windward baffle 24 is determined based on the fluid flow rate: the higher the flow rate, the larger the inlet diameter, and the lower the flow rate, the smaller the inlet diameter. The specific corresponding relationship is not specifically limited in this invention, and the most appropriate diameter size can be determined through experiments or simulations.

[0066] Preferably, the windward baffle 24 of the present invention is inclined from the outer edge to the inner edge toward the inner side, combined with Figure 5 , which shows two cross-sections of the windward deflector 24. The upper cross-section of the windward deflector 24 slopes from the upper left to the lower right, while the lower cross-section of the windward deflector 24 slopes from the lower left to the upper right. Viewed horizontally, the outer edge of the windward deflector 24 is located ahead of the inner edge. The entire windward deflector 24 forms a truncated cone shape, similar to the shape of a trumpet. The windward deflector 24 guides and converges airflow, ensuring a smoother flow.

[0067] The windward deflector 24 has two functions: one is to smooth the airflow through its inclined design; the other is to block and reduce noise transmitted in the reverse direction through the wall surface near the inner circle of the windward deflector 24. Therefore, the windward deflector 24 of the present invention does not necessarily need to be inclined; it can also adopt the same extension trend as the resonant front wall surface 21. These specific embodiments are all within the scope of protection of the present invention.

[0068] The windward side cross section of the windward baffle 24 is streamlined, and the leeward side cross section of the windward baffle 24 is linear. Figure 5The cross section of the windward baffle 24 is a wedge-shaped sharp-angle structure, with the cross section line on the left side being a streamlined curve and the cross section line on the right side being a straight line. The streamlined design of the windward surface of the windward baffle 24 can guide the airflow more smoothly, allowing the airflow to converge more smoothly.

[0069] The inclination angle of the leeward side section of the windward baffle 24 is 10 degrees to 30 degrees. Figure 7 As shown, the angle γ in the figure represents the inclination angle of the leeward side section of the windward baffle 24, that is, the angle between the leeward side section of the windward baffle 24 and the vertical line. By reasonably arranging the inclination angle of the windward baffle 24, it is possible to satisfy the function of guiding the airflow and also to achieve the function of blocking and weakening the reverse noise.

[0070] The windward baffle 24 is a rotating body structure and is centrally symmetrical. It should be noted that the curvature of the windward side surface of the windward baffle 24 is not completely equal at all positions. The curvature near the outer circle is smaller, and the curvature near the inner circle is larger. The curvature of the windward side surface of the windward baffle 24 gradually increases from the outer circle to the inner circle, and the thickness of the entire windward baffle 24 gradually decreases from the outer circle to the inner circle.

[0071] Combine Figure 5 、 Figure 6 As shown, the windward side of the outer edge of the windward baffle 24 is aligned with the windward side of the inner edge of the sound absorbing support shell 1, and no step structure is formed between the sound absorbing support shell 1 and the windward baffle 24, so the airflow can be guided more smoothly. Figure 4 As shown, a ring-shaped step structure is protruded on the windward side of the outer circle of the windward baffle 24, and the ring-shaped step structure cooperates with the inner circle of the sound-absorbing front wall surface 11 of the sound-absorbing support shell 1 to achieve an alignment effect.

[0072] On the basis of any of the above technical solutions and their mutual combination, the present invention sets an inner layer of sound-absorbing cotton 3 in the cavity sandwich between the sound-absorbing support shell 1 and the resonance sound-absorbing inner shell 2, and combines Figure 6 As shown, the inner layer of sound-absorbing cotton 3 mainly consists of three pieces. The inner layer of sound-absorbing cotton 3 is located on the sound-absorbing front wall surface 11 and the resonant front wall surface 21 to form a flat sandwich. The sound-absorbing bottom wall surface 12 and the resonant bottom wall surface 22 form a flat cylindrical sandwich. The sound-absorbing rear wall surface 13 and the resonant rear wall surface 23 form a flat sandwich. The inner layer of sound-absorbing cotton 3 corresponding to the front and rear walls is a ring-shaped flat plate, while the inner layer of sound-absorbing cotton 3 corresponding to the bottom wall is a cylindrical structure.

[0073] The three parts of the inner layer of sound-absorbing cotton 3 can be integrally formed or independently formed. Each of the three parts can also be formed by splicing multiple pieces of sound-absorbing cotton. These specific configurations are all within the scope of protection of the present invention. The widths of the inner layer of sound-absorbing cotton 3 corresponding to the front and rear walls can be equal or unequal. These specific implementations are all within the scope of protection of the present invention.

[0074] The present invention realizes resonant sound absorption through the grooved ring structure cavity structure formed by the resonant sound-absorbing inner shell 2, which is mainly used to weaken medium and low frequency noise. By setting the inner layer of sound-absorbing cotton 3, it is mainly used to weaken high frequency noise, and realizes the noise absorption of different frequencies such as high frequency, medium frequency and low frequency through different methods.

[0075] Combine Figure 6 In the present invention, an annular sound-absorbing cotton 4 is arranged on the inner surface of the sound-absorbing rear wall 13. The annular sound-absorbing cotton 4 protrudes from the inner surface of the sound-absorbing rear wall 13. The annular sound-absorbing cotton 4 can absorb noise and enhance the noise absorption and weakening effect.

[0076] Combine Figure 7 As shown, the cross section of the annular sound-absorbing cotton 4 used in the present invention is triangular, one side of the triangle is glued and fixed to the inner surface of the sound-absorbing rear wall 13, and the other two sides of the triangle face the air inlet direction of the airflow, and one of the two sides facing the air inlet direction of the airflow faces the inner circle direction, that is, Figure 7 The lower left side of the middle, and the other one is facing the outer circle, that is, Figure 7 In the upper left side of the middle, the inclination angle of the surface facing the inner circle is greater than the inclination angle of the surface facing the outer circle. Figure 6 、 Figure 7 As shown, α is the angle between the surface facing the inner circle and the vertical plane, β is the angle between the surface facing the outer circle and the vertical plane, the inclination angle β is greater than the inclination angle α, and the cross-section of the entire annular sound-absorbing cotton 4 is an asymmetric structure, that is, it is not an isosceles triangle, and the three sides of the cross-section triangle are not equal.

[0077] The surface of the annular sound-absorbing cotton 4 facing the inner circle is close to the airflow. Through simulation, it can be seen that the side of the asymmetric annular sound-absorbing cotton 4 close to the airflow is steeper, and the airflow is not easy to form a dead angle, ensuring smooth flow of airflow; the side away from the airflow is flatter, and the flat surface area is larger. The sound is reflected to the annular sound-absorbing cotton 4 many times and absorbed by the annular sound-absorbing cotton 4, reducing noise escape.

[0078] The present invention enhances the noise reduction capacity of the middle anechoic chamber by arranging annular sound-absorbing cotton 4, while avoiding increasing the duct vortex and reducing aerodynamic noise, effectively avoiding increasing the aerodynamic noise at the duct opening, and maximizing the sound absorption and noise reduction effect.

[0079] Specifically, in order to install the annular sound-absorbing cotton 4, an annular groove for clamping the annular sound-absorbing cotton 4 is set on the inner surface of the sound-absorbing rear wall 13. The depth of the annular groove is less than the thickness of the annular sound-absorbing cotton 4. The annular sound-absorbing cotton 4 can be embedded in the annular groove set on the inner surface of the sound-absorbing rear wall 13. The annular groove has a better positioning effect on the annular sound-absorbing cotton 4 and enhances the stability of the annular sound-absorbing cotton 4.

[0080] Combine Figure 7 As shown, a long strip of structure is protruded on the right side of the annular sound-absorbing cotton 4, that is, Figure 7 The right side portion of the dotted line in FIG. 1 matches the annular groove provided on the inner surface of the sound-absorbing rear wall 13 and can be exactly embedded in the annular groove to ensure the stability of the connection.

[0081] It should be pointed out that the cross-section of each side of the annular sound-absorbing cotton 4 can be a straight line or an arc, and these specific implementations should be included in the scope of protection of the present invention; since there are intersections between the side surfaces, the intersections between the side surfaces can form sharp angles, such as Figure 7 In the case shown, a circular arc-shaped smooth transition can also be provided at the junction position, and these specific implementations should all be included in the protection scope of the present invention.

[0082] Specifically, the area of ​​the sound holes in the resonant sound-absorbing inner shell 2 of the present invention is 20%-30% of the overall area of ​​the resonant sound-absorbing inner shell 2. This means that the porosity of the entire resonant sound-absorbing inner shell 2 is 20%-30%, inclusive. By rationally arranging the number and size of the openings, noise is more effectively transmitted through the sound holes into the cavity between the sound-absorbing support outer shell 1 and the resonant sound-absorbing inner shell 2. The distribution of the sound holes in the resonant sound-absorbing inner shell 2 is not limited; a centrally symmetrical arrangement is typically employed.

[0083] The overall structure of the sound-absorbing and noise-reducing device for the front end of an air duct provided by the present invention includes four parts: a sound-absorbing support shell 1, a resonant sound-absorbing inner shell 2, an inner layer of sound-absorbing cotton 3, and an annular sound-absorbing cotton 4. The sound-absorbing support shell 1 is mainly used to provide sufficient rigidity support for the resonant sound-absorbing inner shell 2. Micropores are required at all positions on the resonant sound-absorbing inner shell 2 except for the position of the windward baffle 24. The inner layer of sound-absorbing cotton 3 is sandwiched within the cavity between the sound-absorbing support shell 1 and the resonant sound-absorbing inner shell 2. The annular sound-absorbing cotton 4 is fixed to the inner surface of the sound-absorbing rear wall 13 of the sound-absorbing support shell 1 by gluing. The structural design of the present invention can greatly concentrate the noise in the reverse direction of the flow into the inner cavity of the resonant sound-absorbing inner shell 2, that is, inside the sound-absorbing chamber, and perform various sound absorption and noise reduction through structures and materials such as the sound-absorbing chamber, sound-absorbing cotton, and microporous thin plates, which can have a significant sound-absorbing and noise-reducing effect on the noise at the front end of the air duct.

[0084] The noise reduction device for the front end of the air duct provided by the present invention can specifically weaken the noise transmitted from the fan to the front end of the fan. The innovative structural design scheme can concentrate the noise inside the noise reduction structure and perform multiple noise reductions, thereby enhancing the noise reduction effect without increasing the flow resistance of the air duct.

[0085] The present invention provides a cooling fan, including the above-mentioned noise reduction device for the front end of the air duct, which can achieve the technical effects described above. For other parts of the fan structure, please refer to the prior art and the present invention will not repeat them here.

[0086] Combine Figure 8 In the figure, A represents the fan body, and B represents the noise reduction device for the front end of the air duct provided by the present invention. Arrows indicate the direction of airflow, with air entering from the left and exiting from the right. In this embodiment, the noise reduction device for the front end of the air duct of the present invention is directly fixed to the air inlet of the fan body, with the opening in the center of the noise reduction device facing the fan inlet. Airflow first flows through the noise reduction device and then through the fan body.

[0087] The cooling fan uses the U-shaped grooved annular inner cavity of the noise reduction device to continuously reflect the noise, and its energy is reduced in the process of reflection, thereby achieving the effect of noise reduction; at the same time, with the help of the metal structure of the resonant silencer inner shell 2, the vibration of the noise is converted into the vibration of the metal, which weakens the energy of the noise and achieves the effect of noise reduction; with the help of the sound holes opened in the resonant silencer inner shell 2, the noise enters the cavity interlayer between the sound-absorbing support outer shell 1 and the resonant silencer inner shell 2, and the noise is repeatedly reflected in the cavity interlayer, and finally the noise is weakened, thereby achieving the effect of noise reduction. The structural design in the present invention is mainly used to weaken medium and low frequency noise. The high frequency noise is absorbed by the inner layer of sound-absorbing cotton 3 and the annular sound-absorbing cotton 4. The noise entering the cavity interlayer between the sound-absorbing support outer shell 1 and the resonant silencer inner shell 2 is absorbed and weakened by the inner layer of sound-absorbing cotton 3. The annular sound-absorbing cotton 4 is located near the air flow outlet to absorb the noise inside the resonant silencer inner shell 2.

[0088] Specifically, the silencer and noise reduction device for the front end of the air duct in the present invention is assembled in front of the fan or the front end of the air duct through a bracket, mounting holes, snaps, etc., that is, the silencer and noise reduction device of the present invention can be directly fixed on the fan, or installed in the air intake duct of the fan. The airflow first passes through the silencer and noise reduction device for the front end of the air duct of the present invention, and then passes through the fan.

[0089] For structures using a bracket, it is necessary to fix and install the bracket structure on the rear sound-absorbing rear wall 13 of the sound-absorbing support shell 1 of the sound-absorbing device. The bracket structure is relatively fixedly connected to the fan body. The bracket structure plays a role of transfer and can limit the distance between the sound-absorbing device and the fan body. By setting different distances, different fan structures can be matched or adapted to different internal structures of the chassis. The bracket structure can be fixed to the sound-absorbing support shell 1 in an integrated manner, or a split structural design can be adopted. The bracket is connected to the sound-absorbing support shell 1 and the fan in a detachable manner. The bracket structure can be made of a number of horizontal and vertical intersecting rods without affecting the normal flow of air.

[0090] With the mounting hole structure, it is only necessary to set a hole on the sound-absorbing rear wall 13 and pass a bolt through the hole to achieve a fixed connection. This is a relatively simple and convenient installation method.

[0091] A snap-fit ​​connection requires a male snap on the rear sound-absorbing wall 13 of the sound-absorbing support housing 1 and a female snap on the fan, or alternatively, a female snap on the rear sound-absorbing wall 13 and a male snap on the fan. The male and female snaps mate to achieve a secure connection. This snap-fit ​​connection allows for quick insertion and removal, convenient disassembly and replacement, and facilitates later maintenance, making it a preferred arrangement. However, attention should be paid to the structural strength of the snaps to prevent aging and damage over time.

[0092] The fixing form between the noise reduction device and the fan body is not limited to one type, and multiple different connection structures can be set at the same time, and can be selected according to the needs of use when assembling.

[0093] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A noise reduction device for the front end of an air duct, characterized in that: The sound-absorbing support shell (1) and the resonance sound-absorbing inner shell (2) are nested and installed with each other, and a cavity sandwich for sound absorption is formed between the sound-absorbing support shell (1) and the resonance sound-absorbing inner shell (2), and the two are installed together in front of the fan; The sound-absorbing support outer shell (1) and the resonant sound-absorbing inner shell (2) are both annular in shape, and the resonant sound-absorbing inner shell (2) comprises a resonant front wall surface (21), a resonant bottom wall surface (22), and a resonant rear wall surface (23), wherein the cross section formed by the resonant front wall surface (21), the resonant bottom wall surface (22), and the resonant rear wall surface (23) is in the shape of a U-shaped groove; The resonant sound-absorbing inner shell (2) is a metal microporous plate, and its surface is provided with sound holes in an array; The sound-absorbing support shell (1) and the resonance sound-absorbing inner shell (2) are both thin shell structures, and the sound-absorbing support shell (1) comprises a sound-absorbing front wall surface (11), a sound-absorbing bottom wall surface (12), and a sound-absorbing rear wall surface (13); A windward baffle (24) is provided on the inner edge of the resonant front wall surface (21), and the inner diameter of the windward baffle (24) is smaller than the inner diameter of the sound-absorbing rear wall surface (13).

2. The noise reduction device for the front end of the air duct according to claim 1, characterized in that: The inner diameter of the windward baffle (24) is 80%-95% of the inner diameter of the sound-absorbing rear wall (13).

3. The noise reduction device for the front end of an air duct according to claim 2, characterized in that: The windward baffle (24) is inclined from the outer edge to the inner edge toward the inner side.

4. The noise reduction device for the front end of an air duct according to claim 3, characterized in that: The windward side cross-section of the windward baffle (24) is streamlined, and the leeward side cross-section of the windward baffle (24) is linear.

5. The noise reduction device for the front end of an air duct according to claim 4, characterized in that: The inclination angle of the leeward side section of the windward baffle (24) is 10 degrees to 30 degrees.

6. The noise reduction device for the front end of an air duct according to claim 5, characterized in that: The windward side of the outer edge of the windward baffle (24) is aligned with the windward side of the inner edge of the sound-absorbing support shell (1).

7. The noise reduction device for the front end of an air duct according to any one of claims 1 to 6, characterized in that: An inner layer of sound-absorbing cotton (3) is provided in the cavity sandwich between the sound-absorbing support outer shell (1) and the resonance sound-absorbing inner shell (2).

8. The noise reduction device for the front end of an air duct according to claim 7, characterized in that: An annular sound-absorbing cotton (4) is provided on the inner surface of the sound-absorbing rear wall (13).

9. The noise reduction device for the front end of an air duct according to claim 8, characterized in that: The cross section of the annular sound-absorbing cotton (4) is triangular, and the inclination angle of the surface facing the inner circle is greater than the inclination angle of the surface facing the outer circle.

10. The noise reduction device for the front end of an air duct according to claim 9, characterized in that: The inner surface of the sound-absorbing rear wall (13) is provided with an annular groove for clamping the annular sound-absorbing cotton (4).

11. The noise reduction device for the front end of an air duct according to claim 8, characterized in that: The area of ​​the sound hole provided in the resonance sound-absorbing inner shell (2) is 20%-30% of the overall area of ​​the resonance sound-absorbing inner shell (2).

12. A cooling fan, characterized in that: The invention comprises a noise reduction device for the front end of an air duct as described in any one of claims 1 to 11.

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