PLASTIC NOISE SUPPRESSOR TO CHANNEL FANS Russian patent published in 2018 - IPC F01N1/02 

FIELD: acoustics.

SUBSTANCE: invention relates to the noise suppression equipment. Muffler contains a housing of square cross-section, rigidly connected with end inlet and outlet nozzles, sound-absorbing plates made of a frame containing perforated sheets, filled with a sound absorber and positioned inside housing with certain spacing and forming therein flat channels, between sound absorber and perforated sheets there is an acoustically transparent material, absorber for sound-absorbing plates is made in the form of two outer perforated walls and an inner, middle wall, made in the form of a membrane resonant plate, between which are layers of sound absorbing material, the frame is made symmetrical with respect to the middle wall, which divides it into two congruent parts, each of which has three layers of sound-absorbing material, and more rigid, first layers are made solid, profiled and fixed respectively on the outer perforated walls, second layers, softer than the first ones, are made intermittent and located with a gap in the focus of the sound reflecting surfaces of the first layers, the second layers have a rotation body shape in the form of cones connected by bases, and the first layers are made of a material with a sound reflecting coefficient greater than its sound absorption coefficient in the form of profiles of conical surfaces that focus the reflected sound on the second layers, and the third sound-absorbing layers are made of foamed sound-absorbing material in the form of a construction sealing foam and are located in gaps and voids formed between the first and second layers, each of the outer perforated walls is rigidly connected to the corresponding second layer by means of vertical fastening elements perpendicular to it, made in the form of plates, one end of which is rigidly fixed to the outer perforated wall, and the second end is made in the form of clamps covering the rods respectively and tightening them with screws, while the rods are made parallel to the perforated walls, and the middle wall, made in the form of a membrane resonance plate, is rigidly connected to the frame by means of a construction sealing foam located in the gaps and voids of the frame, characterized in that on one of the oppositely arranged cones of the second layers joined by the bases of the sound absorber cones, resonance holes are realized that fulfill the functions of the neck of the Helmholtz resonators, while the resonant holes are of different diameters to absorb sound energy over a wide frequency range.

EFFECT: higher efficiency of noise suppression.

1 cl, 3 dwg