SOUND-ABSORBING COATING Russian patent published in 2016 - IPC E04B1/84 G10K11/16 

FIELD: acoustics.

SUBSTANCE: sound-absorbing lining is made in form of rigid and perforated walls, between which multilayer sound absorbing element is located made up of two layers, one of which adjoining rigid wall, is sound-absorbing and other adjoining perforated wall is made of sound reflecting material from complex profile composed of evenly distributed hollow tetrahedrons, which enable to reflect sound waves incident in all directions. Perforated wall has following perforation parameters: hole diameter of 3÷7 mm, perforation percentage of 10÷15 %. As for the shape the holes can be circular, triangular, square, rectangular or diamond-shaped. In case of non-circular holes, it is necessary to consider as the nominal diameter the maximum diameter of the circle inscribed in the polygon. Sound-absorbing material used is in the form of Rockwool mineral wool boards on a basalt base or URSA mineral wool or P-75 basalt wool or glass wool lined with glass felt. Sound absorbing element over its entire surface is lined with acoustically transparent material, for example, glass fabric EZ-100 or polymer of “Poviden”, or sound-absorbing material used is porous noise absorbing material, for example foam aluminium, or ceramic metal, or stone-shell limestone with degree of porosity in range of optimal values: 30÷45 %, or metal foam, or material in form of compacted crumbs from solid damping material, for example, polyurethane elastomer or “Agat”, “Antivibrat”, “Schwim” elastrons. Size of fractions of crumbs is within optimal range of values: 0.3…2.5 mm. Porous mineral piece materials are also can be used, for example, pumice, vermiculite, kaolin, slag with cement or other binding, or synthetic fibres. Surface of fibrous sound absorbers is treated with special porous paints, passing air, for example, of “Acutex T” type or coated with air-permeable fabrics or nonwoven materials, for example “Lutrasile”, or sound-absorbing material used is porous fibrous or foam sound-absorbing material, which is based on basalt or glass fibre or open-cell polyurethane foam with protective sound transparent shell of thin glass fabric or aluminised mylar film. As sound reflecting material applied is material based on aluminium containing alloys with their subsequent filling with titanium hydride or air with density within 0.5…0.9 kg/m³ with following strength properties: compression strength within 5…10 MPa, bending strength within 10…20 MPa, for example foam aluminium, or sound insulating plates on the basis of glass staple fibre of “Shumostop” type with density of material equal to 60÷80 kg/m³, or as sound reflecting material applied is material based on magnesite binder with reinforcing glass fabric or glass canvas.

EFFECT: invention allows to improve efficiency of sound absorption and reliability of the structure on the whole.

1 cl, 1 dwg