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

FIELD: machine engineering.

SUBSTANCE: silencer has a housing of rectangular section rigidly connected to the end inlet and outlet branch pipes, a sound absorber located between the perforated element and the sound absorber, and an acoustically transparent material located between the perforated element and the sound absorber. The sound absorber is in the form of a sound-absorbing element of rectangular section, which walls are in the form of rigid and perforated walls, between which two layers are arranged: a sound-reflecting layer adjacent to the rigid wall, and a 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, which can reflect sound waves incident in all directions, or the sound absorber made in the form of a sound-absorbing element of rectangular section, which walls are made in the form of rigid and perforated walls, between which the layers of acoustic reflection are arranged, and the sound-absorbing materials of different density arranged in two layers. The layers of sound-reflecting material are made of complex profile consisting of uniformly distributed hollow tetrahedrons, which allow to reflect sound waves incident in all directions and which are located respectively near the rigid and perforated walls, and the layers of the sound-absorbing material are made of a heat-insulating material configured to maintain the present microclimate in the premise, the sound-absorbing material used is a sheet noise-protective material, which is based on magnesia binder with a reinforcing fibre or fiberglass mat, or a polyester, or porous sound-absorbing ceramic material, having bulk density from 500÷1000 kg/m³ and consisting 100 wt. parts of pearlite with grain diameter from 0.1÷8.0 mm, 80÷250 wt. parts of one of the sintering materials selected from the group including fly ash, slag, quartz, varnish, stone or clay as a base material, 5÷ 30 wt. parts of nonorganic binder. After sintering, the mixture of perlite particles form communicating holes between their contacting surfaces, so that the internal pores are communicating with each other.

EFFECT: increase the efficiency of noise suppression.

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