TUBULAR NOISE SILENCER Russian patent published in 2017 - IPC F01N1/00 

FIELD: machine engineering.

SUBSTANCE: silencer comprises a cylindrical body rigidly connected to the end inlet and outlet branch pipes, a sound absorber placed between the cylindrical body and a perforated element and an acoustically transparent material interposed between the perforated element and the sound absorber. The sound absorber is made in the form of sound-absorbing element of annular type, which walls are made in the form of the rigid and the perforated walls, between which there are two layers: the sound-reflecting layer adjacent to the rigid wall and the sound-absorbing layer adjacent to the perforated wall. The layer of sound-reflecting material is made of a complex profile consisting of uniformly distributed hollow tetrahedrons allowing to reflect the sound waves incident in all directions, or the sound absorber is made in the form of a sound-absorbing element of an annular type, which walls are made in the form of rigid and perforated walls, between which the layers of sound-reflecting and sound-absorbing materials of different density are arranged in two layers. The layers of sound-reflecting material are made of complex profile consisting of uniformly distributed hollow tetrahedrons allowing to reflect sound waves incident in all directions, and which are located, respectively, at rigid and perforated walls, and the layers of the sound-absorbing material are made of a heat-insulating material capable to maintain the preset microclimate in the room, the sound-absorbing material used is a sheet-noise protective material which is made on the basis of a magnesia binder with a reinforcing glass cloth or a fiberglass mat, or a polyester, or a porous sound-absorbing ceramic material of a bulk density of 500÷1000 kg/m³ and consisting of 100 wt. parts of perlite with a grain diameter of 0.1÷8.0 mm, 80÷250 parts by wt. parts of one of sintering materials selected from group including slag, quartz, varnish, stones or clay as a base material, 5÷30 wt. parts of inorganic binder parts. After sintering, the mixture of perlite particles form communicating holes between their contacting surfaces, so that the internal pores communicate with each other.

EFFECT: improved efficiency of noise suppression.

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