KOCHETOV(S NOISE ABSORBING PANEL Russian patent published in 2016 - IPC E04B1/84 G10K11/16 

FIELD: acoustics.

SUBSTANCE: invention relates to industrial acoustics, particularly, to broadband acoustic suppression. Noise absorbing panel comprises a frame and a noise absorbing insert, located in its internal cavity. Frame is made in the form of a parallelepiped formed by front and back walls, each of which has a u-like shape with side ribs. On the walls there is a slot perforation made in the form of rectangles and arranged in rows with width b₁ and b₂ and distances h₁ and h₂ between them, wherein adjacent rows are arranged with an offset, and the number of slots in one row is even, and in the other one - odd. Perforation factor is equal to or bigger than 0.25, and between front and back walls of the frame there is a noise absorbing insert. Wall panels are fixed to each other in the top and in the bottom by vibration-damping covers which can be made with cells and have U-like shape. Front and rear walls of the frame can be made of stainless steel or 0.7 mm-thick galvanised steel sheet with a polymer protective-decorative coating such as 50 mcm-thick "Pural" or 25 mcm-thick "polyester", or 1.0 mm-thick aluminum sheet with 25 mcm-thick coating. Ratio of frame height h to its width b is in the optimal ratio of values: h/b-1.0÷2.0. Ratio of thickness s′ of the frame assembly to its width b is in the optimal ratio of values: s′/b=0.1÷0.15. Ratio of thickness s of sound-absorbing material to thickness s′ of the frame assembly is in the optimal ratio of values: s/s′=0.4÷1.0. Noise absorbing insert is made in the shape of perforated plates, between which there are symmetrically located layers of sound reflecting material, while in the centre, between the layers of sound reflecting material, there are layers of sound-absorbing materials with different density arranged in two layers. Layers of sound reflecting material are made from complex profile composed of evenly distributed hollow tetrahedrons, allowing for the reflection of acoustic waves incident in all directions, and being installed respectively at the perforated plates. Perforated plate can be made of plastic, for instance, caprone, or metal mesh with small cells.

EFFECT: invention allows to increase efficiency of noise absorption due to expansion of frequency range.

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