SOUND ABSORBER Russian patent published in 2017 - IPC F01N1/04 

FIELD: physics.

SUBSTANCE: sound absorber contains a frame made in the form of perforated walls, between which layers of sound-absorbing material are placed. The frame is made in the form of two outer perforated walls and an inner, a middle wall, made in the form of a membrane resonant plate, between which layers of sound-absorbing material are placed. 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, more rigid, the first layers are made solid, profiled and fixed respectively on the outer perforated walls, the second layers, softer than the first, are made discontinuous and are located with a gap in the focus of the sound-reflecting surfaces of the first layers, the second ones are made in the form of rotation bodies in the form of cones connected by bases, and the first layers are made of a material with a sound reflection coefficient greater than its sound absorption coefficient in the form of profiles of conical surfaces which focus the reflected sound on the second layers, the third sound-absorbing layers are made of foam sound-absorbing material in the form of a construction sealing foam and are located in the gaps and cavities 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 and compression screws, respectively, wherein the rods are parallel to the perforated walls, and the middle wall, made in the form of a membrane resonant plate, is rigidly connected to the frame by the construction sealing foam located in the gaps and cavities of the frame.

EFFECT: increased efficiency of noise absorption at low and medium frequencies.

4 cl, 2 dwg