SOUND-ABSORBING LINING Russian patent published in 2017 - IPC E04B1/84 G10K11/16 

FIELD: construction.

SUBSTANCE: sound-absorbing lining is made in the form of a rigid and perforated walls, between which a multilayer sound-absorbing element is located. The multi-layer sound-absorbing element is made in the form of two layers, one of which, adjacent to the rigid wall, is sound-absorbing, and the other, adjacent to the perforated wall, is made of a sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedra, allowing to reflect acoustic waves in all directions. The perforated wall has the following perforation parameters: hole diameter - 3÷7 mm, perforation percentage 10%÷15%, wherein the holes can be made in the form of the holes with round, triangular, square, rectangular or diamond-shaped profile. In the case of non-round holes the conditional diameter is taken as equal to the maximum diameter of the circle inscribed in the polygon. Plates made of basalt-based mineral wool such as "Rockwool", or "URSA" mineral wool, or basalt wool P-75, or glass-wool with a woven glass liner are used as a sound-absorbing material. The sound-absorbing element is lined with acoustically transparent material over the full surface, such as glass fabric EZ-100 or polymer "poviden". A rigid porous material can be used as a sound-absorbing material, such as foam aluminium or cermet, or shell stone with a porosity degree in the range of optimum values: 30÷45%, or metal PU foam, or material in the form of compacted chippings of rigid vibration cushioning materials, such as elastomer, polyurethane, or plastic like "Агат", "Антивибрит", "Швим". The size of chipping fractions lies in the optimal range of values: 0.3…2.5 mm, porous mineral piece materials can also be used, such as pumice, vermiculite, kaolin, slags with cement or another binder, or synthetic fibers. The surface of the fiber sound absorbents is treated with special porous air-permeable paints, such as Acutex T, or is covered with air-permeable fabrics or non-woven materials, such as frost cloth. Material based on aluminium-containing alloys is used as a sound-reflecting material, followed by filling them with titanium hydride or air with a density within 0.5…0.9 kg/m³ with the following strength properties: compressive strength within 5…10 MPa, bending strength within 10…20 MPa, such as foam aluminium, or soundproofing plates based on a glass staple fiber of "Шумoctoп" type with a material density of 60÷80 kg/m³, or a material based on magnesia binder with reinforcing fiberglass or glass wool is used as a sound-reflecting material. The layer adjacent to the perforated wall is made with a perforation from the sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedra.

EFFECT: increased sound-proofing efficiency and design reliability in general.

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