HELICAL-TYPE SOUND ABSORBING ELEMENT Russian patent published in 2018 - IPC E04B1/84 

FIELD: acoustics.

SUBSTANCE: invention relates to industrial acoustics. Screw-type sound-absorbing element contains a smooth and perforated surface, between which is a multi-layered sound-absorbing structure. Sound-absorbing element is made in the form of a cylindrical helical spring, the turns of which in the axial section are made in the form of a rigid and perforated walls, between which two layers are located, one of which, adjacent to the rigid wall, is sound-absorbing, and the other, adjacent to the perforated wall, is made with a perforation from a sound reflecting material of a complex profile consisting of uniformly distributed hollow tetrahedrons. As a sound-reflecting material, a material based on aluminum-containing alloys is used, 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, for example foam aluminum, or soundproofing plates based on a glass staple fiber of the "Shumostop" type with a material density of 60÷80 kg/m³, or a material based on a magnesia binder with reinforcing fiberglass or glass wool. Perforated wall has the following perforation parameters: hole diameter – 3÷7 mm, perforation percentage 10÷15 %. As a sound-absorbing material, mineral wool is used on a basalt basis of the Rockwool type, or mineral wool of the URSA type, or basalt wool of the P-75 type, or glass wool with glass fiber lining, or a foamed polymer, for example polyethylene or polypropylene. Surface of fibrous absorbents is treated with porous paints that let air through.

EFFECT: technical result consists in increased efficiency of acoustic suppression and of the reliability of the structure as a whole.

1 cl, 3 dwg