56results about How to "Guaranteed sound absorption performance" patented technology

The invention relates to a sound barrier structure for high speed railways. The sound barrier structure comprises a steel upright post and a plurality of sound barrier absorption / sound insulation unit plates which are transversely inserted in the steel upright post; elastic rubber is filled in a gap between a flange plate of the steel upright post and the sound barrier absorption / sound insulation unit plate; the sound barrier absorption / sound insulation unit plate comprises a front side plate, a rear side plate, locking buckles, a central framework and a sound absorption material, wherein the front side plate and the rear side plate are locked to a first locking plate and a second locking plate and the upper side and lower side of the central framework through the locking buckles; and the sound absorption material is filled in the gaps inside the locked front and rear side plates. Based on the conventional sound barriers, the sound barrier structure has good economic performance and durability by improving and expanding the types of the conventional sound barriers, and particularly the mechanical strength is greatly improved; and because the technology of bolt-free connection is adopted, the rigidity, shock resistance, fatigue resistance and safety performance of the sound barrier structure are greatly improved.

The invention discloses a non-woven composite material with sound absorption function. The main components comprise terylene staple fiber and hollow staple fiber as well as low-melting fiber, whereinthe terylene staple fiber accounts for 20-40% of the total weight of the components, the hollow staple fiber accounts for 10-30% of the total weight of the components, and the low-melting fiber accounts for 48-52% of the total weight of the components. The non-woven composite material with sound absorption function of the invention has the advantages of good sound absorption performance, no toxicity and no pollution.

The invention discloses a filtering device for pharmaceutical equipment, and belongs to the technical field of pharmaceutical equipment. The filtering device comprises a shell for filtering medicines; and multiple vibration cleaning assemblies which are used for improving the cleaning effect of the filtering structure are installed in the shell. According to the invention, the screw stabilizing assembly is arranged inside, so the condition of motion eccentricity of the lifting screw caused by long-term work can be effectively avoided, and a good rotation effect of the threaded rotary drum matched with the screw stabilizing assembly is ensured; meanwhile, vibration can be effectively conducted into the vibration dredging shaft through the flexible vibration guide rubber, and the vibration dredging shaft can vibrate, so the design is ingenious; on one hand, the flexible vibration guide rubber can effectively reduce vibration of the stable sleeve and guarantee the using effect of the stable sleeve; on the other hand, vibration can be effectively utilized, the vibration dredging shaft of vibration can effectively dredge the interior of the feeding pipe, blockage in the feeding pipe is avoided, unavoidable invalid vibration can be utilized, waste is turned into wealth, and the use effect is improved.

The invention provides an installing construction process of a ceiling clean plate and belongs to the field of manufacturing technologies of building construction. The construction process comprises steps as follows: positions of hanging points on a floor slab are determined firstly; an installing position of a main keel is marked on the bottom surface of the floor slab according to the positions of the hanging points; hanging rods are installed in the positions of the corresponding hanging points and are vertically arranged; the main keel and a light-steel auxiliary keel are installed, wherein the main keel is connected with one end, away from the floor slab, of each hanging rod, and the light-steel auxiliary keel is connected with one side, away from the hanging rods, of the main keel; then the clean plate is installed. During installation of the clean plate, the installing flatness of the clean plate is good; the overall structure is firm after installation, the clean plate is safe and reliable in a use process, and sound-insulation, thermal-preservation, heat-insulation and sound-absorption effects of an aviation workshop can meet the use requirements.

The invention discloses a vertical column sound absorbing structure for a steel structure building and belongs to the technical field of steel structure building auxiliary equipment. The vertical column sound absorbing structure is technically characterized in that the vertical column sound absorbing structure comprises a vertical column; the outer wall of the vertical column is sequentially provided with an annular sound absorbing unit, a first sound absorbing ring and a second sound absorbing ring from inside to outside; the annular sound absorbing unit mainly comprises a plurality of inner sound absorbing rings wrapping the outer wall of the vertical column in a stacked mode in the axial direction of the vertical column, outer sound absorbing rings which are in one-to-one correspondence with the inner sound absorbing rings and are arranged at intervals, and sponge ring cover plates arranged at the two ends of the mutually-matched inner sound absorbing rings and outer sound absorbing rings; the corresponding inner sound absorbing rings and outer sound absorbing rings and the sponge ring cover plates at the two ends are matched to form annular sound absorbing cavities which are each filled with a plurality of sound absorbing sponge blocks; and the filling height of the sound absorbing sponge blocks accounts for 75-85% of the total height of the corresponding annular sound absorbing cavity. The vertical column sound absorbing structure for the steel structure building is compact in structure, convenient to mount and good in use effect, and is used for noise reduction of the steel structure building.

The invention discloses a sound absorption wall, which comprises an inner wall, alkali-free glass sound absorption cotton, metal acoustical boards and keels, wherein embedded elements are arranged in the inner wall; the keels are welded on the embedded elements; the metal acoustical boards are fixed on the keels through screw bolts and screw nuts; and a position between the inner wall and the metal acoustical boards is filled with the alkali-free glass sound absorption cotton. The metal acoustical board perforation rate of the sound absorption wall can reach 40 percent or above. Compared with the prior art, the sound absorption wall has the advantages that the sound absorption efficiency is greatly improved; the structural stability is very good; deformation is avoided; the service life is long; the metal sound absorption wall achieves a good fireproof effect, is nonflammable and has high sound absorption efficiency; the installing and fixing mode of the metal acoustical boards is simple; the single-piece fixation of the metal acoustical boards is realized; and the fixation of other metal acoustical boards cannot be influenced by the mounting or the dismounting of any one metal acoustical board.

The invention provides a rectangular array cylindrical draught fan silencer. The rectangular array cylindrical draught fan silencer comprises a silencer pipe body, wherein an inlet air counter flangeis arranged at an inlet end of the silencer pipe body, an air outlet counter flange is arranged at an outlet end of the silencer pipe body, an air outlet variable diameter shrinkage segment is arranged at one end of the silencer pipe body, an air inlet variable diameter expansion segment is arranged at the other end of the silencer pipe body, and a part, between the air inlet variable diameter expansion segment and the air outlet variable diameter shrinkage segment, of the silencer pipe body, is set as a noise elimination straight cylinder segment. The rectangular array cylindrical draught fansilencer is simple in structure and reasonable in design, enables inlet air to enter noise elimination through holes in a columnar noise elimination plate along inlet air noise elimination channels by using the air noise elimination channels among adjacent noise elimination columns, and thereby achieves noise control, controls noise below 85 decibels, reduces influence from high noise to workers,and then improves work efficiency of the workers, and furthermore can prevent that second wind noise is caused due to the fact that the inlet air hits the noise elimination columns and guarantee noise elimination effects by using stream guidance arcs installed at air inlet ends of the noise elimination columns.

The embodiment of the invention discloses double-sided black polyester sound-absorbing cotton. The double-sided black polyester sound-absorbing cotton comprises a first non-woven fabric layer, a second non-woven fabric layer and a sound-absorbing cotton layer. The upper surface of the sound-absorbing cotton layer is attached to the lower surface of the first non-woven fabric layer. The lower surface of the sound-absorbing cotton layer is attached to the lower surface of the second non-woven fabric layer. The first non-woven fabric layer comprises the following components in parts by weight: 95-99 parts of polyester material, 0.5-4 parts of carbon black, and 0.5-1 part of carbon black dispersing agent. The second non-woven fabric layer comprises the following components in parts by weight:95-99 parts of polyester material, 0.5-4 parts of carbon black, and 0.5-1 part of carbon black dispersing agent. The sound-absorbing cotton layer comprises the following components in parts by weight:95-99 parts of PET polyester fiber, 0.5-4 parts of white carbon black and 0.5-1 part of carbon black dispersing agent. The double-sided black polyester sound-absorbing cotton is convenient to process, high in sound-absorbing performance and high in decoration performance.

The invention discloses a multi-cavity sandwich type micro-perforated plate silencing structure. The silencing structure comprises a micro-perforated plate, wherein the micro-perforated plate is of acylindrical structure, and the exterior is provided with a shell; a resonance cavity of an annular structure is arranged between the shell and the micro-perforated plate; a plurality of partition plates are arranged between the shell and the micro-perforated plate in the radial direction; the partition plates divide the resonance cavity into a plurality of small resonant cavities with the same size; a sandwich plate is arranged in each small resonant cavity along the circumferential direction of the micro-perforated plate; a closed inner cavity is formed among the sandwich plates and the partition plates and the micro-perforated plate; a closed outer cavity is formed among the sandwich plates and the partition plates and the shell; and the shell and the two ends of the micro-perforated plate are connected through flanges. The micro-perforated silencing structure provided by the invention has the sound absorption performance of the medium-low frequency band and the medium-high frequencyband, is high in mechanical property, and is a multifunctional integrated structure for mechanically bearing-wide-frequency sound absorption.

The invention relates to a manufacturing, forming and processing method for a heat-preservation and heat-insulation acoustic board, wherein a heat-preservation and heat-insulation acoustic board manufacturing, forming and processing machine is used. The machine comprises a working plate, supports and drilling devices, wherein the supports are symmetrically installed on the left side and the right side of the lower end of the working plate, and the drilling devices are arranged on the upper end face of the working plate. According to the drilling device, the problems that when the heat-preservation and heat-insulation acoustic board is drilled, a large amount of dust and sweeps are often generated in the drilling process due to the fact that sound-absorption holes are densely distributed, dust dispersed in air can reduce comfort of the working environment, potential safety hazards can be possibly brought to workers may be solved, and the problems that manpower and material resources are wasted as it is needed to clean dust and sweeps generated subsequently, the sound absorption effect of the sound absorption holes is reduced as burrs and sweeps may appear on the inner walls of the sound absorption holes after the sound absorption holes are drilled, and meanwhile, the overall sound absorption and heat preservation effect of the sound absorption board may be affected are solved.

The invention discloses a partition perforated square tube space sound absorber, and relates to the technical field of building material decoration. The partition perforated square tube space sound absorber comprises a keel assembly and a square tube assembly, the keel assembly comprises a keel body, a pair of symmetrical limiting protruding strips are arranged on one side of the keel body, the two limiting protruding strips are close to the two side edges of the keel body respectively, and the two limiting protruding lines are matched with the keel body to form two mounting grooves; and the square tube assembly covers the keel assembly, a pair of opposite connecting plates is arranged on the side, close to the keel assembly, of the square tube assembly, the two connecting plates and the two mounting grooves are mounted in a one-to-one correspondence mode, and at least one gap is formed in the square tube assembly, so that the partition perforated square tube space sound absorber forms a Helmholtz resonator. The partition perforated square tube space sound absorber can realize a good sound absorption effect, and can also avoid pollution to an indoor environment.

The invention relates to the field of sound absorption and insulation materials, in particular to a sand-coated sound absorption board based on a gypsum board. The sand-coated sound-absorbing board based on the gypsum board comprises a sound absorption coating, a gridding cloth and a gypsum board base plate, wherein the sound absorption coating, the gridding cloth and the gypsum board base plate are arranged in sequence. The compositions of the sound absorption coating comprise filler and inorganic binder, and the filler comprises silica sand and resin particles. The sand-coated sound-absorbing board based on the gypsum board has excellent sound absorption ability.

The invention provides a building board which is of a three-dimensional net rack structure. The building board comprises surface layers located on the surfaces of the two sides of the board, a middle sound insulation layer located between the surface layers, and light sandwich layers located in filling gaps between the surface layers and the middle sound insulation layer. The surface layers and the middle sound insulation layer are made of sound insulation materials or composite sound insulation materials. The light sandwich layer is made of sound absorption materials. The building board is characterized by further comprising keels located between the surface layers and the middle sound insulation layers and connected with the surface layers, and the keels and the middle sound insulation layer are integrally formed into the three-dimensional net rack structure, or the keels, the middle sound insulation layer and the surface layers are integrally formed into the three-dimensional net rack structure. The building board has excellent sound insulation performance, and meanwhile the building board has good thermal insulation performance and is firm in structure, simple, reasonable, light in weight, thin, convenient to install, simple in production and manufacturing process and low in cost.

The invention discloses a manufacturing method of a wall sound insulation material, and relates to the related field of wall sound insulation material manufacturing. The invention aims at solving theproblems that in the prior art, sound insulation materials prepared after materials are combined are insufficient in adhesiveness, and cracks, stripping and the like can occur when the materials act on the wall. The method comprises the following steps: separating barks and stems of obtained branches to prepare crushed plant fibers; preparing foam concrete, and crushing the foam concrete; preparing silicon dioxide sol, and adding a silane coupling agent, an expanding agent and an antioxidant into the silicon dioxide sol; adding the obtained lower-layer static precipitate and the obtained lower-layer filter residue into a wet mixture, and mechanically stirring and mixing to obtain a sound insulation material matrix; preparing a sound insulation material mixed filler; adding the sound insulation material matrix into the sound insulation material mixed filler; and extruding, dehydrating and drying the plant fibers, adding the plant fibers into the mixture, and mechanically stirring and mixing.

The invention discloses a track bed sound-absorbing plate and a preparation method thereof. The track bed sound-absorbing plate comprises a main body and a plurality of wedges arranged on the top surface of the main body along a longitudinal direction. The sound-absorbing plate is prepared from ceramsite aggregates and a cement cementitious material and has an ash collection ratio of 0.3-0.5. Theceramsite aggregate comprises first ceramsites with diameters of 1-5mm and second ceramsites with diameters of 5-10mm. The top surface of the sound-absorbing plate is provided with the convex and concave wedges. Through the principle of gradual transition of sound waves, the effect of high-frequency sound absorption is improved, air pressure waves are reduced, acoustic pressure is relieved, and the influence caused by pressure waves on vehicles is reduced. The porous sound-absorbing plate prepared from the ceramsites with different diameters has a honeycomb continuous pore structure, producesthe wide-band response to sound waves, guarantees the sound-absorbing effect and high strength and durability of the product, has good water permeability, can smoothly drain away accumulated water andproduces good sound-absorbing effects through matching with the internal microporous structure of the ceramsite.

The invention discloses a noise reduction device. The device comprises a box body, one side of the box body is an elastic layer made of an elastic material, noise reduction holes are formed in the elastic layer, and the noise reduction device also comprises a deformation mechanism for driving the elastic layer to deform. The invention also discloses a range hood applying the noise reduction deviceand a control method of the range hood. Compared with the prior art, the device has the advantages that through the arrangement that the shape of at least one side of the noise reduction device can be adjusted, it is convenient to take targeted noise reduction measures for different working conditions; when applied to the range hood, and a vortex and a boundary layer of airflow inside the range hood can be separated for controlling rectification, so that air impact born by an impeller of a fan system is uniform, the noise of the air impact is reduced, the load on a motor is stable, trip stopwhen the range hood operates in different gears is prevented, and a good oil fume absorption effect when a user uses the range hood is ensured under different back pressure conditions at an outlet ofthe range hood.

The invention discloses a composite building wall module, a module building wall and a preparation method and application. The composite building wall module sequentially comprises a cement mortar surface layer, a bonding reinforcing layer, a first thermal insulation layer, a first glass fiber reinforced composite board, a second thermal insulation layer and a second glass fiber reinforced composite board from one side to the other side; the first glass fiber reinforced composite board is provided with a plurality of reinforcing ribs, and the first thermal insulation layer is connected with the first glass fiber reinforced composite board through reinforcing ribs; the first glass fiber reinforced composite board is connected with the second glass fiber reinforced composite board through atleast four light steel connecting parts, one side of the composite building wall module is at least provided with a light steel connecting part, each light steel connecting part comprises two parallel side plates and a bottom plate, one sides of the side plates are connected with the bottom plate, one side plate is connected with the first glass fiber reinforced composite board, the other side plate is connected with the second glass fiber reinforced composite board, and the two light steel connecting parts are arranged to be connected in a matched mode through the bottom plates.

The invention discloses a preparation method of aerogel glass. The preparation method comprises the following steps: weighing raw materials including aerogel powder and a methyl methacrylate matrix according to weight, adding the prepared methyl methacrylate matrix into a reaction kettle, stirring to convert the methyl methacrylate matrix into a prepolymer, so that the conversion rate of the prepolymer reaches 25-35%, adding the weighed aerogel powder into the prepolymer with the conversion rate of 25-35%, continuously stirring and uniformly mixing to form a mixed prepolymer, enabling the conversion rate of the mixed prepolymer to reach 50%, filtering the mixed prepolymer, then adding the filtered mixed prepolymer into a mold, and carrying out vibration exhausting, promoting final polymerization until the mixed prepolymer in the mold is in a gel state, and continuously heating and keeping the temperature, so that the mixed prepolymer in the gel state forms formed aerogel organic glass.According to the preparation method, aerogel particles of various specifications are uniformly mixed with the organic glass prepolymer, so that the aerogel organic glass which is low in heat conductivity coefficient, high in mechanical strength, good in sound absorption and noise reduction effect and convenient to mount and use is obtained.

The invention provides a sound-absorbing and sound-insulation material. The sound-absorbing and sound-insulation material comprises the following components in parts by weight: 10-15 parts of rubber,10-15 parts of PVC, 10-15 parts of a foaming agent, 18-24 parts of a filler, 3-7 parts of carbon black, 17-22 parts of paraffin, 2-5 parts of chlorinated polyethylene, 1-5 parts of slab beeswax, 1-4 parts of soybean oil, 0.5-3 parts of a surfactant and 0.5-4 parts of calcium stearate. By adding a mixed material comprising the PVC, the rubber and the foaming agent, and optimizing the usage amountsof the components, the purpose that the prepared material has large and small holes can be effectively achieved; and the overall sound-absorbing performance of the sound-absorbing material is effectively ensured.

The invention discloses a sound absorption board, and relates to the technical field of railway construction materials. The sound absorption board comprises a square plate that is cube-shaped; a cross concave groove which extends to four longitudinal end surfaces of the square plate is formed in the bottom part of the square plate. Compared with the prior art, the sound absorption board has the advantage that the problems of poor sound absorption effect, easy cracking, and inconvenient use of the existing sound absorption board can be solved.

The invention discloses an automobile carpet structure which comprises a carpet surface layer, a glue film or glue powder layer and a felt layer from top to bottom. The carpet surface layer comprisesa surface layer, a film attaching layer and a base layer, the surface layer comprises 85% of PET and 15% of LPET, and the surface density is 200 to 450 g / m<2>; the film attaching layer comprises a PEfilm, and the surface density is 70 to 120 g / m<2>; the substrate layer comprises 85% of PET and 15% of LPET, and the surface density is 300 to 600 g / m<2>; the thickness of the carpet surface layer is3 to 6mm, the glue film or glue powder layer comprises a PE film or adhesive powder, the surface density is 70 to 120g / m<2>; the felt layer comprises an equal-density PET felt, the surface density is600 to 2000g / m<2>, and the thickness is 3 to 25mm. According to the automobile carpet structure, by improving the carpet layer structure, the weight of the carpet is reduced while the sound absorptionand insulation performance is guaranteed, the density and the use range of heavy layers in all areas of the carpet are adjusted, the use amount of the heavy layers is reduced, and meanwhile VOC emission of the whole carpet is reduced. The invention further discloses a specific arrangement mode for the carpet structure.

The invention relates to the technical field of building construction, in particular to a noise reduction and dust removal electric drill with a scrap collecting structure. The electric drill comprises an electric drill body and the scrap collecting structure, the scrap collecting structure comprises a front end, a middle end, a rear end and a storage cavity, the front end, the middle end and the rear end are attached to the surface of a wall, the rear end is glidingly connected with an electric drill chuck, a noise reduction assembly is arranged in a cavity of the middle end and comprises an outer sound absorption layer and an inner sound absorption layer, a sound absorption cavity is further formed between the inner sound absorption layer and the outer sound absorption layer, a plurality of buffer springs are arranged in the sound absorption cavity, and the noise reduction and dust removal electric drill further comprises a control system used for ensuring that the noise reduction assembly can absorb sound and reduce noise in real time. The invention further provides a control method of the noise reduction and dust removal electric drill. The electric drill is simple in structure, reasonable in design and convenient to disassemble, time and labor are saved, the real-time noise reduction and sound absorption effects of the electric drill are effectively guaranteed, the construction cost is saved, and the relatively-quiet construction environment of constructors is guaranteed.

Provided is a pneumatic tyre in which a sound-absorbing material is effective in absorbing sound during high-speed travel and the sound-absorbing material can be prevented from separating or breakingin low temperatures. A pneumatic tyre provided with: a tread part (1) which extends in the circumferential direction of a tyre so as to form a ring shape; a pair of sidewall parts (2) arranged on therespective sides of the tread part (1); and a pair of bead parts (3) arranged on the inner sides, in the radial direction of the tyre, of the sidewall parts (2), wherein a sound-absorbing material (6)is fixed, via an adhesive layer (5), to the inner surface of the tread part (1), along the circumferential direction of the tyre, and when the temperature t of the sound-absorbing material (6) is atleast in the range -20 degrees to 80 degrees, the rupture elongation y [%] of the sound-absorbing material (6) satisfies the relationships y>=t+100 and y<=2t+440 with respect to the temperature t of the sound-absorbing material (6).

The invention provides a convenient-to-adjust communication equipment sound absorption device, which comprises a sound absorption box, iron sheets, a ventilation opening, a cooling shell, a heat dissipation motor, heat dissipation blades, an air outlet, an air exhaust net, an air inlet and an air inlet net. The upper and lower parts of the front part of the right side of the sound absorption box are in screw connection with the iron sheets. A ventilation opening is formed in the middle of the right portion of the inner side of the sound absorption box. A cooling shell is arranged on the rightside of the ventilation opening and connected with the sound absorption box through screws. Through the arrangement of the sound absorption piece, the mounting plate, the movable plate, the U-shaped sliding block, the linear sliding rail and the square head bolt, communication equipment can be fixedly mounted, the sound absorption position can be adjusted, the sound absorption and noise reductioneffects are guaranteed, the communication equipment can be mounted and fixed through the mounting plate, sound absorption is conducted through the sound absorption piece, and according to the operation requirement, The square-head bolt can be loosened, the position of the U-shaped sliding block on the outer wall of the linear sliding rail is moved and adjusted, and after the position is determined, the square-head bolt is locked, so that operation convenience is guaranteed.

The invention relates to the technical field of sound absorption technologies and purification technologies, in particular to an air purification and sound absorption composite structure. The air purification and sound absorption composite structure comprises a micro-perforated plate substrate and air purification units, wherein a sound absorption back cavity is formed between the micro-perforated plate substrate and a mounting surface, mounting portions are arranged on the micro-perforated plate substrate, and the air purification units are arranged in the mounting portions. According to the air purification and sound absorption composite structure, the micro-perforated plate substrate is connected with the mounting surface to form the sound absorption back cavity, the sound absorption back cavity and the micro-perforated plate substrate play a resonance function, and different sound absorption requirements are met by adjusting the parameters of the micro-perforated plate substrate; and different purification requirements are met by selecting or changing the purification parameters of a filling material of the air purification units and the area ratio of the air purification units and the micro-perforated plate substrate. The air purification function is achieved while the sound absorption effect of the sound absorption structure is guaranteed, the occupancy rate of the separate use space is reduced, and optimization of the space is facilitated.

The invention relates to the technical field of titanium-zinc plates, and discloses a heat-resistant and corrosion-resistant titanium-zinc plate. The heat-resistant and corrosion-resistant titanium-zinc plate comprises a metal base plate. Supporting profile steel is fixedly connected to the top of the metal base plate, wiping strips are fixedly connected to the top of the supporting profile steel,a heat insulation layer is fixedly connected to the top of the supporting profile steel, and a sound absorption bottom plate is fixedly connected to the top of the heat insulation layer. According tothe heat-resistant and corrosion-resistant titanium-zinc plate, the supporting profile steel, the wiping strips and the heat insulation layer are arranged on the top of the metal base plate, and therefore the good supporting performance is provided for the whole structure through the transverse and vertical connection of the supporting profile steel and the wiping strips advantageously; the soundabsorption bottom plate, supporting strips, a sound absorption layer and an air isolation layer are arranged on the tops of the wiping strips, the sound absorption layer and the supporting strips arefixed in a penetrating and inserting mode, and therefore the sound absorption effect of the whole structure is improved conveniently. Meanwhile, the supporting strips ensure the stability of a soundabsorption structure, and the air isolation layer effectively avoids the phenomenon that due to the fact that the moisture enters the sound absorption structure, the sound absorption performance is reduced.

The invention relates to a wind shield for reducing noise and a cooling fan with the same. The wind shield comprises a base, a fan opening is formed in the base, and a ring is arranged around the fanopening; a resonance sound absorption structure is arranged on the inner side of the ring and comprises a hard plate with a plurality of holes and a sound absorption material; and the sound absorptionmaterial is fixed on the inner side of the ring and arranged between the hard plate and the inner side of the ring. According to the wind shield and the cooling fan, the hard plate with the pluralityof holes and the sound absorption material can form a plurality of Helmhz resonant cavities with different sound absorption frequencies, so that the sound absorption effect of the wind shield on thenoise with the frequency of hundreds to thousands of hertz is guaranteed, and the wide-band noise is reduced advantageously.