A noise reduction device for axial flow fans

Abstract

This utility model relates to the field of noise reduction device technology, specifically: a noise reduction device for an axial flow fan, including a frame, on which a fan body is fixedly connected. A noise reduction sleeve is fitted over the fan body. The noise reduction sleeve, from the inside out, consists of a flexible buffer noise reduction inner layer, a gradient porous sound absorption layer, a damping constraint vibration reduction layer, a nanocomposite sound insulation layer, a multifunctional protective outer layer, and a reinforcement layer. In this utility model, the noise reduction sleeve enables efficient control of noise across the entire frequency band of the fan body. The flexible buffer noise reduction inner layer reduces vibration transmission and noise leakage, the gradient porous sound absorption layer enhances the absorption of mid-to-high frequency noise, the damping constraint vibration reduction layer suppresses structural vibration, and the nanocomposite sound insulation layer blocks residual noise, significantly improving the overall noise reduction capability.

Description

Technical Field

[0001] This utility model relates to the field of noise reduction device technology, and in particular to a noise reduction device for axial flow fans. Background Technology

[0002] Axial flow fans are widely used in numerous fields such as industrial production, building ventilation, rail transportation, and household appliances due to their advantages such as large air volume, strong pressure head adaptability, relatively simple structure, and convenient installation. In industrial workshops, they can quickly achieve air circulation and exchange, ensuring air quality in the production environment; in subway tunnels, they play a vital role in removing polluted air, introducing fresh air, and handling emergency smoke extraction; in household air conditioning equipment, they are key components for achieving heat exchange between indoor and outdoor air, directly affecting cooling and heating performance, and have become core equipment for ensuring air circulation and normal equipment operation in various fields.

[0003] However, axial flow fans generate significant noise during operation. The sources of this noise are complex, including aerodynamic noise, mechanical noise, and electromagnetic noise. This noise not only interferes with communication during industrial production but also affects residents' daily rest and relaxation. Utility Model Content

[0004] In view of the technical problem that existing axial flow fans generate significant noise during operation, this utility model provides a noise reduction device for axial flow fans.

[0005] The technical solution adopted by this utility model is: a noise reduction device for an axial flow fan, including a frame, on which a fan body is fixedly connected, and a noise reduction sleeve is fitted on the outside of the fan body. The noise reduction sleeve is composed of a flexible buffer noise reduction inner layer, a gradient pore sound absorption layer, a damping constraint vibration reduction layer, a nanocomposite sound insulation layer, a multifunctional protective outer layer, and a reinforcement layer from the inside to the outside.

[0006] In one embodiment, the flexible buffer noise reduction inner layer is made of modified polyurethane elastomer material with a thickness of 1.5-2.5 mm.

[0007] In one embodiment, the gradient pore sound-absorbing layer is made of melamine foam material with a thickness of 20-25 mm.

[0008] In one embodiment, the damping constraint vibration reduction layer is a three-layer composite material composed of a metal sheet, a polymer damping material, and a metal sheet, with a thickness set to 1.5-2 mm.

[0009] In one embodiment, the nanocomposite sound insulation layer is made of butyl rubber composite material modified with nano-silica, and the thickness is set to 15-20 mm.

[0010] In one embodiment, the multifunctional protective outer layer is made of glass fiber reinforced polytetrafluoroethylene composite material with a thickness of 5-8 mm.

[0011] In one embodiment, the reinforcing layer is a reinforced filter plate with a thickness of 5 mm.

[0012] The beneficial effects of this utility model are as follows: Compared with the prior art, this utility model can efficiently control the noise of the fan body across the entire frequency band by setting the noise reduction sleeve. The flexible buffer noise reduction inner layer reduces vibration transmission and noise leakage. The gradient pore sound absorption layer enhances the absorption of mid-to-high frequency noise. The damping constraint vibration reduction layer suppresses structural vibration. The nanocomposite sound insulation layer blocks the remaining noise, greatly improving the overall noise reduction capability. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the noise reduction sleeve in this utility model; Figure 3 This is a schematic diagram of the structure of the fan body in this utility model; Figure 4 This is a schematic diagram of the layered structure of the noise reduction sleeve in this utility model.

[0014] The components in the diagram are labeled as follows: 1. Fan body; 2. Frame; 3. Noise reduction sleeve; 4. Heat dissipation fins; 5. Flexible buffer noise reduction inner layer; 6. Gradient pore sound absorption layer; 7. Damping constraint vibration reduction layer; 8. Nanocomposite sound insulation layer; 9. Multifunctional protective outer layer; 10. Reinforcement layer. Detailed Implementation

[0015] In the description of this utility model, it should be noted that the terms "front", "up", "down", "left", "right", "vertical", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not 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 utility model.

[0016] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0017] The following is in conjunction with the appendix Figure 1-4The present invention will be further described below.

[0018] To address the problems existing in the background technology, this application proposes the following technical solution: a noise reduction device for an axial flow fan, characterized in that it includes a frame 2, a fan body 1 fixedly connected to the frame 2, a noise reduction sleeve 3 sleeved on the outside of the fan body 1, and heat dissipation fins 4 fixedly connected to the outside of the noise reduction sleeve 3 for heat dissipation. The noise reduction sleeve 3 is composed of a flexible buffer noise reduction inner layer 5, a gradient pore sound absorption layer 6, a damping constraint vibration reduction layer 7, a nanocomposite sound insulation layer 8, a multifunctional protective outer layer 9, and a reinforcing layer 10 from the inside out, and they are bonded and fixed to each other.

[0019] The above technical solution is explained as follows: 5. Material selection for the flexible buffer and noise reduction inner layer: Modified polyurethane elastomer material is used. This material is made by adding nano-sized calcium carbonate particles and nitrile rubber powder to ordinary polyurethane elastomer.

[0020] Thickness setting: The thickness is set to 8-12mm.

[0021] The existing technology briefly describes the production method as follows: Injection molding is used for production. The specific production process is as follows: First, modified polyurethane elastomer raw materials (including polyurethane prepolymer, nano-sized calcium carbonate particles, nitrile rubber powder, catalyst, crosslinking agent, etc.) are added to a high-speed mixer according to a certain formula ratio. The mixture is thoroughly mixed at a specific temperature and speed to form a homogeneous mixture. Then, the mixture is added to the barrel of an injection molding machine, where it is melted and plasticized by heating the barrel. Next, the screw of the injection molding machine injects the molten mixture into a pre-set mold cavity at a certain pressure and speed. Finally, after a certain period of pressure holding and cooling, the mold is opened, the product is removed, and subsequent processing steps such as trimming and polishing are performed to obtain the finished flexible cushioning and noise reduction inner layer 5. Injection molding has advantages such as high production efficiency, high product dimensional accuracy, and ease of molding complex shapes. It can meet the needs of mass production of the flexible cushioning and noise reduction inner layer 5, and can be customized according to the size and shape of different axial flow fans to produce highly adaptable products.

[0022] Material selection for the gradient pore sound-absorbing layer 6: Melamine foam material with a gradient pore structure. Melamine foam material has the advantages of high porosity, low density, good sound absorption performance, excellent fire resistance (high oxygen index), and environmental friendliness and non-toxicity, making it an ideal sound-absorbing material.

[0023] Thickness setting: The thickness is set to 20-25mm.

[0024] The existing technology briefly describes the production method as follows: It employs a compression molding foaming process combined with a subsequent pore gradient treatment process. The specific production steps are as follows: First, prepare the melamine foam raw material liquid. Melamine, formaldehyde, catalyst, surfactant, etc., are added to a reaction vessel according to a certain formula ratio. A condensation reaction is carried out at a certain temperature to form a melamine-formaldehyde resin prepolymer. Then, a foaming agent is added and stirred evenly to obtain the melamine foam raw material liquid. Second, inject the raw material liquid into a specific mold and place it in a foaming furnace for foaming molding. The foaming temperature and time are controlled to allow the foam to initially form. Third, perform pore gradient treatment on the initially formed foam using a special laser. The process involves drilling and chemical etching techniques to increase the porosity and pore size on one side of the foam (near the flexible buffer noise-reducing inner layer 5), while maintaining a relatively smaller porosity and pore size on the other side (near the damping constraint vibration reduction layer 7), thus forming a gradient pore structure. The fourth step involves drying and curing the treated foam to remove moisture and volatile substances, improving its stability and mechanical properties. Finally, the foam is cut and trimmed according to the overall size requirements of the noise-reducing sleeve 3 to obtain the finished gradient pore sound-absorbing layer 6. This existing technology can be briefly described in its production method as follows: it can precisely control the pore gradient distribution of the material, ensuring the stability and consistency of sound absorption performance, while also offering high production efficiency suitable for mass production.

[0025] Material selection for the damping constraint vibration reduction layer 7: A sandwich composite structure of "metal sheet, polymer damping material, and metal sheet" is adopted. The metal sheet is made of cold-rolled steel with a thickness of 0.2-0.3mm. Cold-rolled steel has good rigidity and strength, providing effective constraint for the damping material. The polymer damping material is a copolymer of butyl rubber and acrylate. This material has excellent damping performance, with a damping loss factor (tanδ) reaching 0.3-0.5 at room temperature (25℃), effectively absorbing vibration energy and suppressing structural vibration. The butyl rubber and acrylate copolymer not only has good damping performance but also good aging resistance, oil resistance, and water resistance, enabling it to adapt to different environmental conditions.

[0026] Thickness setting: The overall thickness is set to 1.5-2mm.

[0027] The existing technology briefly describes the production method as follows: It employs a hot-press composite molding process. The specific production flow is as follows: First, the cold-rolled steel sheet undergoes surface pretreatment, including degreasing, rust removal, and phosphating, to improve the cleanliness and roughness of the steel sheet surface and enhance its bonding strength with the polymer damping material. Then, the pretreated cold-rolled steel sheet and polymer damping material are stacked sequentially in a composite mold in the order of "steel sheet-damping material-steel sheet". Next, the mold is placed in a hot press and hot-pressed under specific temperature (120-150℃), pressure (5-10MPa), and time (10-20min) conditions. During the hot pressing process, the polymer damping material melts and flows, tightly bonding with the upper and lower cold-rolled steel sheets. Finally, the composite-molded sheet is removed from the mold, cooled and shaped, and then cut, stamped, and processed according to the size requirements of the noise reduction sleeve 3 to obtain the finished damping constraint vibration reduction layer 7. Hot-press composite molding process can ensure high bonding strength between the layers of materials, stable and reliable product performance, and is suitable for industrial mass production.

[0028] Material Selection for Nanocomposite Sound Insulation Layer 8: Butyl rubber composite material modified with nano-silica. Butyl rubber itself has good sound insulation properties and elasticity, but its sound insulation performance still has room for improvement in the high and low frequency ranges. By adding nano-silica particles to modify butyl rubber, the sound insulation performance of the material can be further improved. The particle size of the nano-silica particles is 20-50nm, and the addition amount is 8%-12% of the total mass of butyl rubber. The nano-silica particles can be uniformly dispersed in the butyl rubber matrix to form a dense sound insulation structure, effectively blocking the propagation of sound waves.

[0029] Thickness setting: Set the thickness to 15-20mm.

[0030] The existing technology briefly describes the production method as follows: It employs a mixing process using an internal mixer followed by calendering. The specific production steps are as follows: First, raw material pretreatment: Butyl rubber raw material is placed in an oven for preheating and softening (temperature controlled at 60-80℃, time 30-60 min). Nano-silica particles and tungsten powder are dried separately (temperature 100-120℃, time 2-3 h) to remove moisture and prevent air bubbles from forming during subsequent mixing. Second, mixing in an internal mixer: The preheated butyl rubber raw material is added to the internal mixer for plasticizing (temperature 110-130℃, speed 30-50 r / min, time 5-8 min) to give the rubber a certain degree of plasticity. Then, nano-silica particles, tungsten powder, vulcanizing agent, accelerator, and other auxiliary materials are added sequentially, and mixing continues (temperature controlled at 130-150℃, speed 20-40 r / min, time 1...). The process involves several steps: 1) **calendering:** The mixed rubber compound is placed between the rollers of a calender and calendered under specific temperature (90-110℃), pressure (15-25MPa), and speed (1-3m / min) conditions to form a sheet material with a certain thickness and width. 2) **vulcanization:** The calendered sheet material is placed in a vulcanizing tank and vulcanized at 150-170℃ and 2-3MPa for 15-20 minutes to induce a cross-linking reaction, forming a stable three-dimensional network structure and improving the material's mechanical and sound insulation properties. Finally, the vulcanized sheet material is cut according to the size requirements of the noise reduction sleeve 3 to obtain the finished nanocomposite sound insulation layer 8. This production process has advantages such as high production efficiency, stable product quality, and suitability for large-scale industrial production, ensuring the consistent performance of the nanocomposite sound insulation layer 8.

[0031] The multifunctional protective outer layer uses nine materials: glass fiber reinforced polytetrafluoroethylene (PTFE) composite material. PTFE possesses excellent corrosion resistance (withstanding strong acids, alkalis, and oxidants), high temperature resistance (long-term operating temperature range of -200℃ to 260℃), weather resistance (resistant to aging and degradation in outdoor environments), and good electrical insulation, making it an extremely stable polymer material. By adding glass fibers to reinforce and modify PTFE, the material's mechanical properties, such as tensile strength, flexural strength, and abrasion resistance, are significantly improved, preventing the inherent weakness of PTFE materials that makes them prone to breakage.

[0032] Thickness setting: The thickness is set to 5-8mm.

[0033] The existing technology briefly describes the production method as follows: Production is carried out using a compression molding process. The specific production process is as follows: First, raw material preparation: Polytetrafluoroethylene resin powder, glass fiber, halogen-free flame retardant, fluorocarbon surfactant, etc., are added to a high-speed mixer according to a certain formula ratio and mixed at 800-1000 r / min for 15-20 minutes at room temperature to ensure uniform dispersion of each component and form a mixed powder. Second, pre-compression molding: The mixed powder is loaded into a pre-set mold and pre-compressed at 20-30 MPa at room temperature (holding time is 5-10 minutes) to form a green body with a certain shape and density. Third, sintering molding: The pre-compressed green body is placed in a sintering furnace. In the process, sintering is carried out according to a set heating curve: first, the temperature is slowly increased from room temperature to 200℃ (heating rate of 5-10℃ / min), and held for 1-2 hours; then, the temperature is further increased to 380-400℃ (heating rate of 2-5℃ / min), and held for 3-4 hours to allow the polytetrafluoroethylene resin to fully melt and combine with other components; finally, the temperature is slowly reduced to room temperature (cooling rate of 5-10℃ / min) to avoid stress cracking inside the material due to excessively rapid cooling; in the fourth step, subsequent processing is performed, and the sintered product is removed from the mold for surface polishing, cutting, and other treatments to obtain a multifunctional protective outer layer that meets the dimensional requirements. The compression molding process ensures that the product has high density and dimensional accuracy, stable performance indicators, and is suitable for mass production.

[0034] In summary, the noise reduction sleeve 3 has a clearly defined and coordinated six-layer structure from the inside out, which can effectively control the noise of the fan body 1 across the entire frequency band. The flexible buffer noise reduction inner layer 5 reduces vibration transmission and noise leakage, the gradient pore sound absorption layer 6 enhances the absorption of mid-to-high frequency noise, the damping constraint vibration reduction layer 7 suppresses structural vibration, and the nanocomposite sound insulation layer 8 blocks residual noise, thus greatly improving the overall noise reduction capability.

[0035] All standard parts used in this utility model can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art. In addition, the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0036] Although embodiments of the present invention have been shown and described, the scope of the present invention will be defined by the appended claims and their equivalents for those skilled in the art.

Claims

1. A noise reduction device for an axial flow fan, characterized by, Includes a frame (2), on which a fan body (1) is fixedly connected. The fan body (1) is covered with a noise reduction sleeve (3). The noise reduction sleeve (3) consists of a flexible buffer noise reduction inner layer (5), a gradient pore sound absorption layer (6), a damping constraint vibration reduction layer (7), a nanocomposite sound insulation layer (8), a multifunctional protective outer layer (9), and a reinforcement layer (10) from the inside out.

2. The noise reduction device for an axial flow fan according to claim 1, characterized in that, The flexible buffer noise reduction inner layer (5) is made of modified polyurethane elastomer material with a thickness of 1.5-2.5 mm.

3. The noise reduction device for an axial flow fan according to claim 2, characterized in that, The gradient pore sound-absorbing layer (6) is made of melamine foam material with a thickness of 20-25 mm.

4. The noise reduction device for an axial flow fan according to claim 3, characterized in that, The damping constraint vibration reduction layer (7) is a three-layer composite material made of metal sheet, polymer damping material and metal sheet, with a thickness of 1.5-2mm.

5. A noise reduction device for an axial flow fan according to claim 4, characterized in that, The nanocomposite sound insulation layer (8) is made of butyl rubber composite material modified with nano silica, and the thickness is set to 15-20 mm.

6. The noise reduction device for an axial flow fan according to claim 5, characterized in that, The multifunctional protective outer layer (9) is made of glass fiber reinforced polytetrafluoroethylene composite material with a thickness of 5-8 mm.

7. A noise reduction device for an axial flow fan according to claim 6, characterized in that, The reinforcing layer (10) is a reinforced filter plate with a thickness of 5 mm.

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