KOCHETOV SPHERICAL ACOUSTIC ABSORBER Russian patent published in 2016 - IPC E04B1/84 

FIELD: acoustics.

SUBSTANCE: invention relates to means of reducing noise in industrial and transport facilities. Spherical acoustic absorber comprises active and reactive acoustic absorbers located on a rigid frame. This frame is made of two parts, the lower reactive part is made in form of a structure of spherical shape with internal congruent spherical resonant cavity formed by rigid spherical enclosure equidistant outer perforated spherical shell connected with top active part that is made in the form of a rigid perforated cylindrical shell with perforated cover and solid base, the cavity of cylindrical shell is filled with sound absorbing material. Connection of top and bottom parts of sound absorber is made by resilient damping element ensuring dampening of HF oscillations. To perforated cover of perforated cylindrical shell element is pivotally connected, using it framework is secured to required facility, for example, to ceiling of production room. Spherical resonance cavity of the reactive part of the frame is rigidly connected at least via one sleeve with axial bore used as the neck of Helmholtz resonator with external perforated spherical enclosure, the space between them is filled with sound absorber. Around perforated cylindrical shell there is at least one screw sound absorbing element made in form of cylindrical coil spring enclosing shell. Screw sound-absorbing element is made as a hollow screw sound-absorbing element made up by outer and inner screw surfaces forming a cavity. Space formed outer and inner surfaces of screw is filled with sound-absorbing material having a density less than that of screw sound-absorbing element. Cavity of the screw sound absorbing element formed by its outer and inner screw surfaces is filled with sound absorbing material made from mineral wool on basalt base Rockwool or URSA or P-75 basalt wool or glass wool lined with glass felt. Sound-absorbing material over its entire surface is lined with acoustically transparent material, for example, glass fabric EZ-100 or polymer of "poviden" type. Outer and inner screw surface of the screw sound absorbing element are made from material based on aluminium alloys with subsequent filling by titanium hydride or air with density within 0.5…0.9 kg/m³ with the following strength properties: compression strength within 5…10 MPa, bending strength within 10…20 MPa, for example the foamed aluminium.

EFFECT: technical result consists in improvement of efficiency of noise suppression at high frequencies by insertion in the sound absorber of volume cavities for Helmholtz resonators, which improve efficiency at high frequencies.

1 cl, 1 dwg