90results about How to "Sound absorption frequency bandwidth" patented technology

The invention relates to a multiple helmholtz resonator parallel cellular sandwich wood sound absorption plate, belonging to the field of sound absorption technologies. The invention solves the problems of small chamber volume ratio, narrow sound absorption frequency band and poor sound absorption effect in the traditional sound absorption panels. Technical essential is characterized in that a sandwich layer is a cellular sandwich layer; the cellular sandwich layer is formed from splicing a plurality of cylinder bodies with hexagonal cross sections; an inner cavity of each hexagonal cylinder body is a cell cavity chamber; the chamber volume ratio of the sandwich layer is larger than 90%; the area of perforation shape surrounded by contour lines of each perforation is less than a half of the hexagonal area of corresponding sandwich layer; and each small through hole on a panel is communicated with the cell cavity chamber at the corresponding position of the sandwich layer. The invention has wider sound absorption frequency band and better medium high frequency sound absorption performance, and the sanding wave tube method sound absorption coefficients respectively reach 0.8, 0.9 and 0.7 at 500Hz, 1000Hz and 2000Hz. In addition, the invention also has the characteristics of light weight, high ratio of strength to weight, good decorative effect, and the like; and wood resources can be saved, preparation process is simple, and cost is low.

A non-wool sound screen with engaged cavities and sound absorptive surfaces is composed of two aluminium fibres sheet layers as surficial layers, two empty cavity layers, two microhole plat layers, a toothed cavity, folded partion, and fixing frame. Its advantage is high effect to decrease noise.

The invention relates to a composite resonance sound absorption device of a tube bundle perforated plate, comprising a sealed cavity composed of a perforated plate, a back plate and a lateral plate; the perforated plate is penetrated with superfine seams and voids; a tube bundle is formed by arraying N pieces of tubes which are placed in the sealed cavity, and one end of each tube penetrates intothe perforated plate or is inserted into the perforated plate by a transient joint to be connected with the perforated plate, and the other end thereof is an open or sealed end; the diameter of the tube is equal to that of the void; the external surface of the perforated plate is coated with a layer of porous sound absorption material; and N is less than or equal to the number of 6 of the voids. The invention combines the resonance sound absorption structure, superfine seam sound absorption structure and porous sound absorption material of the tube bundle perforated plate, uses the sound absorption theory of dissipating and absorbing through tube cavity coupling resonance and superfine seam resonance as well as porous sound absorption material to add acoustic resistance, intensify sound absorption, increase sound quality, lead the resonance absorption peak to move to low frequency, expand sound absorption frequency band, enhance sound absorption coefficient and realize the aim of broadband sound absorption.

The invention discloses an adaptive micro-perforated plate sound absorber and a real-time micropore adjusting method thereof. The sound absorber comprises a micro-perforated plate, wherein micropores are uniformly distributed on the micro-perforated plate; the micro-perforated plate is a piezoelectric film micro-perforated plate, is made from a piezoelectric film, and is provided with a circuit lead end connected with a piezoelectric film electrode; the circuit lead end is connected with an active control circuit; the active control circuit comprises a piezoelectric film driving circuit, an adaptive controller and a noise detector which are connected with the circuit lead end in turn; and a cavity formed by the piezoelectric film micro-perforated plate and side walls and a rear wall at the periphery of the plate is a piezoelectric film micro-perforated plate resonant sound absorption structure. The size of the micropores on the piezoelectric film micro-perforated plate is adjusted in real time through the piezoelectric effect of the piezoelectric film, so that the aims of optimizing the sound absorption coefficient of the micro-perforated plate resonant sound absorption structure in real time according to the sound wave characteristic of incident noise and greatly expanding the effective sound absorption frequency band of the micro-perforated plate resonant sound absorption structure can be fulfilled.

The invention relates to a composite sound-absorbing structure made of porous material and resonance structure. The composite sound-absorbing structure is composed of porous materials encapsulated by upper panels, lower panels and side panels. From the upper panel to the lower panel, the void size or porosity of the porous material gradually changes in order from small to large or from large to small; the space enclosed by the upper panel, the lower panel and the side panel is filled with porous material 1; the upper panel It is a perforated plate, and the lower panel is a perforated plate or a non-porous baffle. The composite sound-absorbing structure proposed by the present invention has a wider sound-absorbing frequency band than the porous material with uniform pore size and porosity, which can improve the sound-absorbing performance in the middle and low frequency bands while maintaining the sound absorption in the high-frequency band. Sound absorption performance.

The invention provides a thin broadband sound-absorbing structure. The structure comprises a sound-absorbing material, a support and at least two layers of mechanical impedance plates, wherein the sound-absorbing material is installed on the inner side of one end of the support, a supporting plate is arranged on the inner wall of the other end of the support, each of the mechanical impedance plates consists of a back plate and sticky elastic rings at two ends of the back plate, adjacent back plates are not in contact, sticky elastic rings are stuck to the supporting plate through an adhesive, the sticky elastic rings, the support inner wall and the back plates are attached tightly, a hollow is formed among the sound-absorbing material and the mechanical impedance plates, and the back plate on the outermost side is recessed towards the support end face by certain distance. Mechanical impedance is coupled to a traditional sound-absorbing material and a cavity resonance absorption mechanism, a novel thin broadband sound-absorbing mechanism is formed, the structure thickness is not increased basically based on the acoustic performance, the middle/high-frequency sound absorption performance is good, the low-frequency sound absorption effect is improved greatly and the sound-absorbing structure of which the thickness is thin and the sound-absorbing frequency band is wide is produced.

The invention provides a microporous-fiber composite sound absorbing board, belonging to the field of instruments for absorbing noises through adopting the resonance principle. The sound absorbing board has a good low-frequency sound absorbing effect, and the sound absorbing coefficient of the sound absorbing board is larger than 0.5 at 125Hz. Compared with an aluminum fiber absorbing board, the sound absorbing board has a wider absorbing absorption band. The sound absorbing coefficient of the sound absorbing board is not smaller than 0.4 at 250-1600Hz. The composite sound absorbing board is formed by compounding a micro-perforated board with an aluminum fiber board and adopts a double-resonance coupling structure. The micro-perforated board is connected with the aluminum fiber board through a keel frame to form a first resonating cavity, and the aluminum fiber board is connected with a wall through the keel frame to form a second resonating cavity. The micro-perforated board and the aluminum fiber board are coupled through a resonance peak to achieve the purposes of increasing the low-frequency sound absorbing effect and expanding the absorbing absorption band. The composite sound absorbing board adopting an all aluminum structure has the characteristic of good recycling, and the problems of aging, dropping and the like do not exist. The sound absorbing board also has the characteristic of good heat conduction, and is convenient for equipment to dissipate heat.

The invention relates to a porous foam dual-surface sound adsorption ultra-thin sound baffle, belonging to the noise control technique. It comprises: two layers of porous plates, two layers of chambers, two groups of non-fiber sound adsorption porous material, a trapezium chamber, a folded baffle plate, and the frame. Wherein, two layers of chambers are arranged between the two layers of porous plates and two groups of non-fiber sound adsorption porous material; the trapezium chamber is arranged between two groups of non-fiber sound adsorption porous material and the folded baffle plate; the frame can fix the porous plates and the folded baffle plate; two groups of non-fiber sound adsorption porous material are fixed on the folded baffle plate; each back of said groups of non-fiber sound adsorption porous plates has a group of trapezium chamber; and two groups of trapezium chambers are meshed and filled by non-fiber sound adsorption porous material. the invention can be mounted between the upper and lower rails of railway or city road or between the driveways to reduce the traffic noise.

The invention relates to an efficient sound-absorbing ceramsite, belonging to the technical field of a building material. Aiming to solve the problems that city pollution can not be well solved, product properties are poor, the poor sound-absorbing effects are poor and the production cost is high in the prior art by mainly using the shale as ceramsite, can be solved, The invention provides the efficient sound-absorbing ceramsite, which is prepared from raw materials mainly consisting of raw materials of 60-80% of sludge, 5-20% of the shale, 5-20% of coal ash and 1.0-10% of additive. The efficient sound-absorbing ceramsite provided by the invention has the properties of wide sound-absorbing frequency band, fire resistance, good durability, freezing resistance, seismic resistance, high sound-absorbing coefficient, high porosity, light weight, high strength, heat resistance, anti-permeability and the like. The efficient sound-absorbing ceramsite further can be used for preparing a road barrier and a metro sound-absorbing material and has wide application prospect. Furthermore, the efficient sound-absorbing ceramsite provided by the invention mainly uses city sludge, so that not only can the problem of the city sludge be solved well, but also the overuse of a natural resource of the shale is reduced.

The invention discloses a sound absorption and insulation sandwich plate with a labyrinth back cavity, and the sound absorption and insulation sandwich plate comprises the labyrinth back cavity. Perforated plates, damping elastic layers and mixed metal plates are in turn symmetrically superimposed on the front side and the back side of the labyrinth back cavity. The labyrinth back cavity is with.The shapes of the labyrinth back cavity, the perforated plates, the damping elastic layers and the mixed metal plates are regular shapes or irregular shapes, and the regular shapes include a circle, an ellipse and a polygon. The labyrinth back cavity, the perforated plates, the damping elastic layers and the mixed metal plates are sealed with damped slurry to prevent leakage, and are connected andfixed together by bolts. Incident sound waves can be reflected multiple times inside a sound insulation layer, the sound insulation quantity can be significantly improved; the resonant cavity can beincreased while increasing of the resonance efficiency, and the sound absorption coefficient is enhanced; the sound absorption frequency band is increased and broadened; and the sound absorption coefficient can be increased while adjusting of the absorption frequency band.

The invention belongs to the acoustical technical field and relates in specific to a novel non-fiber type and micropunched sound absorption type sound barrier body with transition cavity. The invention comprises a micropunched panel, a top face, a bottom face, a left end face, a right end face and a back plate; the micropunched panel, the top face, the bottom face, the left end face, the right end face and the back plate are connected to form a closed cavity; the cavity depth appears in a linear transition; the maximum depth is 2.5 to 3.5 times as the minimum depth. The micropunched panel is arranged with micropores with total occupied area of 0.5 percent to 3 percent of the panel area; the micropore aperture is 0.6 to 1.2mm. In actual use, it is only necessary to mount the invented device into a sound barrier vertical column or other places for sound absorption process. The invented device is characterized in being simple, easy and convenient manufacturing, thin shape and being light and having perfect sound absorption performances. Sound absorption band width with sound absorption factor higher than 0.4 exceeds 2 octaves. Therefore, the invention has advantages of broad application scope, easy purging, high-temperature resistance, and superior weather ability. Besides, the invented device can be completely recycled for use to thoroughly avoid the problem of secondary pollution, for which the invention has superior environmental protection function.

The invention discloses a polymer film sound absorbing material and a preparation method thereof, wherein the material consists of polyaniline or polypyrrole, nano-additive and film-forming assistant agent, and the polymer film is prepared by these materials in ratios according to the changing mode of the conductivity. The film has wide sound absorbing frequency band and strong sound absorbing ability, wherein the average sound absorbing coefficient is bigger than 0.5 in the frequency range from 125Hz to 4000Hz, and the biggest sound absorbing coefficient reaches 0.95, thereby overcoming the defect that the low frequency band of a normal sound absorbing material has bad sound absorbing effect. The material quality of the film sound absorbing material is light and thin, the thickness thereof is only between 0.2 and 0.6 millimeters and the weight thereof in each square kilometer is only between 200g and 500g.

The invention is a high molecular sound absorbing composite and the preparing method and use thereof, characterized by comprising high molecular grain layer, high molecular porous layer and high molecular pierced layer, arranging the three layers of high molecular materials in a fixed die box in a mode of gradient variation of acoustic impedance and bonding the die box with surface layers of the high molecular material together. In a range of 300-2000Hz, it has average sound absorbing coefficient greater than 0.4, strong sound absorbing ability with the maximum sound absorbing coefficient up to 1.0, and wide sound absorbing frequency range, and its noise reducing coefficient is up to 0.68 and simultaneously it is thinner.

The invention relates to a motorbike muffler, in particular to a noise piezoelectric power generation self-powered magneto-rheological muffler used for motorbikes. The noise piezoelectric power generation self-powered magneto-rheological muffler comprises a hollow barrel. An air inlet pipe and an air outlet pipe are arranged at the two ends of the axis of the barrel correspondingly. The barrel comprises a shell and a fixing body. A plurality of cylindrical holes are formed in the fixing body, and magnetic cones are arranged in the cylindrical holes. The magnetic cones are composed of cylindrical permanent magnets and first conical magnetorheological fluid which is covered onto the permanent magnets after magnetization. The barrel is internally divided into a first cavity, a second cavity and a third cavity through a left partition plate and a right partition plate in the direction perpendicular to the axis of the barrel. A damping unit is arranged in the second cavity. A crankshaft inthe first cavity is sleeved with fan blades, and each fan blade is formed by bonding a circular ring-shaped piezoelectric crystal plate and a metal base plate. The piezoelectric power generation self-powered magneto-rheological muffler used for the motorbikes has the advantages and characteristics that continuous change of the acoustic impedance gradient of the magnetic cones and the fan blades are used for achieving dynamic active sound absorption, acoustic energy is converted into heat energy, and acoustic impedance can be self-adjusted.

The invention belongs to the technical field of air-cooled refrigerator air channel noise reduction and discloses a sound absorption structure of an air channel. The structure comprises two or more layers of thin plates which are fixed to the inner side of an air channel wallboard in sequence from outside to inside, cavities are reserved between every two adjacent thin plates and between each thin plate and the air channel wallboard respectively, and each thin plate is provided with through holes used for communicating the cavity at the inner side of the thin plate with the cavity at the outer side of the thin plate. According to the sound absorption structure of the air channel, due to the fact that the plates are thin and hole diameters are small, the acoustic resistance of the air channel is larger than that of a conventional perforated plate, the mass is small, and therefore structure of the air channel is better than the structure of the conventional perforated plate in effect regarding the acoustic absorption coefficient and the frequency band. The sound absorption structure of the air channel is constituted by the two or more layers of thin plates, therefore the frequency band is widened and moves toward the low frequency, as air channel noise is usually located in the low frequency band, the sound absorption frequency band is wide, the sound absorption effect in the medium and low frequency band is good, and the air channel noise can be effectively reduced. On the whole, the sound absorption structure of the air channel is low in cost, wide in sound absorption frequency band and high in sound absorption coefficient.

The invention provides a sound-absorbing and insulating barrier board with a wide sound-absorbing frequency band and good sound-absorbing and insulating effects, which includes a panel and a backboard. Installed on the frame, a cavity is formed between the panel and the back plate, and sound-absorbing material is arranged in the cavity. The surface and the back panel are respectively fixed to the skeleton so that the barrier panel has a strong resistance to external force loads, and the sound-absorbing material is arranged between the panel and the back panel to make the barrier panel have better sound absorption and sound insulation effects.

The invention discloses a structure parameter design method for suppressing a nonlinear effect of a micro-perforated plate. The method comprises the steps that first, a high-sound-intensity noise field is subjected to frequency spectrum and sound pressure level analysis, and limiting condition parameters and to-be-designed parameters are determined according to frequency domain distribution of noise energy; second, a group of {d,t/d} parameters are selected; third, a corresponding perforation rate sigma is calculated; fourth, a curve of micro-perforated plate structure acoustic impedance Z changing along with an incidence sound pressure level P is drawn through numerical simulation according to a parameter combination {d,t/d,sigma} and a known parameter f<0>; and fifth, the relation curve of the acoustic impedance changing along with the incidence sound pressure level in the third step is observed, and a transformation sound pressure level corresponding to the nonlinear acoustic impedance which starts to work is obtained. According to the method, the nonlinear effect of a sound absorption structure of the micro-perforated plate under high sound intensity is effectively suppressed, so that the micro-perforated plate has good linear sound absorption performance within a given sound pressure level range, and the sound pressure level range which the sound absorption structure of the micro-perforated plate can be effectively applied to is greatly expanded.