RU2019136014A - PIECE SOUND ABSORBER - Google Patents

Claims (2)

A piece sound absorber, consisting of a perforated frame filled with sound-absorbing material placed in a protective shell, the frame is made of a rigid perforated outer cylindrical shell, which is connected by means of rigid upper and lower flat bases to a rigid inner, coaxially located, cylindrical shell, with the cavity between shells are filled with sound-absorbing material, for example, mineral wool on a basalt basis of the "Rockwool" type, or mineral wool of the "URSA" type, and the sound-absorbing material along its entire surface is lined with acoustically transparent material, for example, glass cloth of the EZ-100 type or polymer of the "Poviden" type this to the bases of the frame, inside it, axisymmetrically and coaxially to the inner cylindrical shell of the frame with the formation of a cavity, a cylindrical hollow rod made of sound-reflecting material is fixed, the inner cavity of which is filled with sound-absorbing material, and to the rigid perforated outer cylindrical shell of the frame, the resonant part of the sound absorber is attached, made in the form of at least two necks of the Helmholtz resonator, made in the form of cylindrical tubes rigidly connected to the outer cylindrical shell of the frame, and installed perpendicular to its axis, while the cavities of the tubes are connected with a cavity formed by a rigid inner, coaxially located, cylindrical shell, and a rod, and serving as a resonant cavity of the Helmholtz resonator, the volume of which is calculated for the required frequencies, the noise level at which must be reduced using the resonant part of the sound absorber, characterized in that the cylindrical hollow rod, made of sound-reflecting material, the inner cavity of which is filled with sound-absorbing material, contains at least two resonance chambers, interconnected by a resonant insert, which in turn is connected by a resonant insert to a resonance clear cavity of the Helmholtz resonator, formed by the bases of the frame, its inner cylindrical shell and the outer cylindrical shell of the hollow rod, made of sound-reflecting material, while the sound-reflecting material of the cylindrical hollow rod is a material based on a foil, or fiberglass, or carbon fiber, or plastic containing carbon fibers are used as a reinforcing filler, and polyester is used as a sound-absorbing material filling the inner cavity of the rod, or a porous fibrous or foamy sound-absorbing material based on basalt or glass fibers, or open-cell polyurethane foam with a protective sound-transparent shell made of thin glass cloth or aluminized lavsan film, while a porous sound-absorbing ceramic material is used as a sound-absorbing material, having a bulk density of 500 ÷ 1000 kg / m ³ , and consisting of 100 mass parts perlite with a particle diameter of 0.5 ÷ 2.0 mm, 100 ÷ 200 mass parts of one or more sintering materials and 10 ÷ 20 mass parts of binders, or a heat-resistant highly porous fibrous heat-insulating and sound-absorbing material made of mineral a filler in the form of silica fibers, a binder, a sintering additive, which is used as amorphous boron or boron nitride, and a surfactant, while silica fiber having a diameter of 4-10 μm is used as a binder and simultaneously the surfactant used an aqueous solution of one of the substances selected from the group including methylcellulose, carboxymethylcellulose or carboxymethyl starch, the content of which is 2-5 wt. %, and additionally the material contains silica sol with the following ratio of components, wt. %: Silica fiber with a diameter of 4-10 microns 75.0-92.8 Amorphous boron or boron nitride 0.2-0.5 Silica 7.0-25.0