KOCHETOV SOUND ABSORBER OF CIRCULAR TYPE Russian patent published in 2016 - IPC E04B1/84 

FIELD: acoustics.

SUBSTANCE: invention relates to industrial acoustics, particularly to sound-absorbing devices of circular type. Device is made in form of a ring, comprises rigid and perforated walls. Between walls there is a five-layer sound-absorbing element. Two of layers adjacent to walls are sound-absorbing layers from materials of different density. Three central layers are combined. Axial layer is sound-absorbing. Two symmetric layers adjacent to axial layer are made from sound reflecting material from complex profile composed of evenly distributed hollow tetrahedrons, which enable to reflect sound waves incident in all directions. Each of perforated walls has following perforation parameters: hole diameter - 3÷7 mm, perforation percentage 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-translucent material is sewed to line said sound absorbing material over its entire surface. Sound reflecting material used is material based on aluminium-containing alloys with subsequent filling thereof 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. Sound reflecting material used can be material based on magnesite binder with reinforcing glass or glass cloth.

EFFECT: higher efficiency of sound absorption and reliability of design overall.

1 cl, 1 dwg