KOCHETOV SINGLE-PIECE SPHERICAL ACOUSTIC ABSORBER Russian patent published in 2016 - IPC E04B1/84 G10K11/16 

FIELD: acoustics.

SUBSTANCE: invention relates to means of reducing noise in industrial and transport facilities. Single spherical acoustic absorber comprises active and reactive acoustic absorbers located on rigid frame. Frame is made of two parts. Bottom reactive part is made in form of 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, which is made in form of rigid perforated cylindrical shell with perforated cover and solid base. 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 reactive part of frame is rigidly connected by at least one sleeve with axial bore that doubles as Helmholtz resonator neck with external perforated spherical enclosure. Space between them is filled by 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 by outer and inner surfaces of screw is filled with sound-absorbing material having density less than that of screw sound-absorbing element. Perforated surfaces have following perforation parameters: holes diameter is 3÷7 mm, perforation percentage is 10÷15 %. Holes in perforated surfaces can be made in form of circular, triangular, square, rectangular or rhomboid shape. 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. As materials of perforated surfaces can be applied structural materials with layer of soft vibration dampening material applied on their surfaces from one or two sides, for example of paste material of VD-17 type, or “Gerlen-D” type material, wherein ratio between thicknesses of material and vibration damping coating is within optimal range of values: 1/(2.5…3.5), or from stainless steel, or galvanized steel sheet with thickness of 0.7 mm with polymer protective-decorative coating such as “Pural” with thickness of 50 mcm or “Polyester” with thickness of 25 mcm, or aluminium sheet with thickness of 1.0 mm and coating thickness of 25 mcm, or from solid decorative damping materials, for example, “Agat”, “Antivibrat”, “Schwim” elastrons. 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 absorbing element on its entire surface is lined with an acoustically transparent material, for example, EZ-100 glass cloth or Poviden polymer.

EFFECT: higher efficiency of noise suppression at high frequencies.

1 cl, 1 dwg