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 located in its internal cavity noise absorbing insert. 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 front wall there is a slot perforation made in the form of rectangles and arranged in rows, while the width of rows is b₁ and b₂ and the distance between them is h₁ and h₂. Adjacent rows are arranged with an offset, and the number of slots in one row is even, and in the other - odd. Perforation factor is equal or bigger than 0.25. Between the front and rear 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 height h of the frame to its width b is in the optimal ratio of values: h/b = 1.0÷2.0. Ratio of thickness s' of 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 rigid and perforated plates, between which there are symmetrically located layers of sound reflecting material, while in the centre, between layers of sound reflecting material, there are layers of sound-absorbing material of different density arranged in two layers. Layers of sound reflecting material have a complex profile composed of evenly distributed hollow tetrahedrons, which enable reflection of sound waves in all directions and are located, respectively, near the rigid and 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 by expanding the frequency range, to ensure simplification and universality of panel installation and to improve its operating properties.

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