Luggage acoustic muted rhythmic (options)

 

(57) Abstract:

The invention relates to acoustic measurements, analysis of sound waves, sound-absorbing structures. According to the first variant of the invention, the proposed acoustic camera muffled rhythmic, with limited surfaces of the walls of the volume, the measuring microphone and a material consisting of a layer of glass wool, the electromagnetic screen and through an air gap layer of sound-absorbing wedges. When this layer of glass wool has a thickness of 150-900 mm and pressed to the walls of the steel sheet or wire mesh with a spacing of 0.05-0.5 mm and the air gap has a thickness of 10-15 mm According to the second variant, the layer of glass wool is pressed against the walls of the resonant absorber from a cloth of thick fabric. The electromagnetic shield may be made of two parallel layers of metal sheet and parallel to a metal grid or of two parallel layers, made of metal mesh, dividing the thickness of the layer of glass wool in the ratio of 1:2. Resonant absorber may consist of two parallel layers of thick fabric, placed at a distance from the walls, not exceeding the thickness of a layer of glass wool, and dividing the thickness of the layer of glass wool is>The invention relates to acoustic measurements, analysis of sound waves, sound-absorbing structures and may find application in the design, construction, certification and operation of acoustic, muffled, rhythmic cameras.

There is a Luggage acoustic, muffled, rhythmic, intended for tests and measurements of the acoustic characteristics of the sound emitters (1).

The camera consists of surfaces that form a closed volume, the electromagnetic screen of steel 3 mm sheet, and an absorber, consistently covering the surface. The absorber consists of a consistently applied to all the bounding surface layer of mineral glass wool with a thickness of 100 mm and through an air gap in 50-70 mm layer of sound-absorbing wedges height from 500 to 1250 mm and above, depending on the class of the camera.

The analyzed sound source is placed in the center of the anechoic chamber on a special table, and the sounds emitted by them are recorded by the measuring microphone and, falling on the inner surface, is absorbed by the absorber.

The drawback of this camera is that if the high and medium frequency sound waves are well reflected from the bounding surfaces, gets to the measuring microphone distorts the frequency response of the investigated sound emitter. To combat this drawback OST 4.275 000-79 divides camera acoustic, rhythmic 5 classes, in which cameras vary in size and length of the sound-absorbing wedges, which allows the lower edge frequency of the camera with a 100 Hz (class 4) reduce to 31.5 Hz (0 a "higher" class).

Another drawback of the camera is that as the main material used sound-absorbing wedges from staple fiber grade 150 (specific weight of 150 kg/m), the absorption of which at frequencies below 100 Hz low. In accordance with (1) a rhythmic muted cameras are characterized by an internal volume having the shape of a parallelepiped. The inner surface of the camera consistently covered the electromagnetic screen of 3 mm steel sheet, 100-mm layer of glass wool 150 brand of staple fiber and 50 mm air gap with a layer of sound-absorbing wedges with a base of 200 mm x 200 mm and a height of from 500 to 1250 mm, depending on the grade of your camera. In accordance with (1) a rhythmic anechoic chambers are divided into 5 classes from 4 to 0 (highest).

Their main characteristics are shown in table.

Not the absorption of the materials, faced with a wall of cameras, falls, and to receive an echo-free space at frequencies below 100 Hz in accordance with (1), the volume of the inner surface and the thickness of the sound absorbing layer increases (see table) and metrological characteristics muted rhythmic cameras are divided into 5 classes in order to reduce lower the cutoff frequency from 100 to 31.5 Hz. Another disadvantage rhythmic acoustic camera including (1) that as an electromagnetic screen used sheet steel of thickness not less than 3 mm, which covers the inner bounding surface with a density of 7.9 g/cm3greater density of all building materials used in the construction of the camera. There is a sound absorbing structure for an acoustic anechoic chambers (2). To improve the design in the design of the camera used sound-absorbing wedges the same length 500 mm, and a layer of glass wool changes in the design of the camera from 150 to 900 mm and pressed against the bounding surfaces of the layer of metal mesh or sheet steel with holes over the entire area. There is a broadband absorber (3), which can be used when developing and manufacturers offering is s, the absorber consists of a adjacent to each other of the sections having in cross section the shape of a triangle, with the base coinciding with the front plane of the absorber, and the space between the side walls of each section divided by a longitudinal partition into a geometric, having in cross section the shape of parallelograms, camera kit air resonators, consisting of several families of identical resonators, so that each new family of cell sizes less than half, and the number of them is twice more than the previous collection of larger resonators and the same camera always separated from each other larger, with each camera set by their angle, in which the throat of the resonator, for example a slit that goes on the front of the plane of the absorber. The disadvantage of this material is that for the excitation of oscillations, consuming energy, used air volume, and to provide sound absorption at lower frequencies, it is necessary to increase the amount of material that is unacceptable constructively, and also increase the complexity of setting the lower cutoff frequency. There anechoic chamber (4), characterized primarily by the fact that the ferrite plate. The drawback of this camera is its low coefficient of sound absorption at low frequencies.

From all the above analogs (1-4) is most similar in its characteristics to the proposed acoustic chamber is the acoustic camera is described in the analog (1), as it allows you to use their design features to eliminate the main drawback is the low coefficient of sound absorption at low frequencies. To address this shortcoming in muted rhythmic chamber upon layer of sound-absorbing wedges placed resonant heat sinks, which increase the coefficient of sound absorption at low frequencies. In order salinovic period worked as a resonant absorber him on the depth 150 mm fill mineral glass wool brand 150 and press it to the internal surfaces of the thick cloth of tarpaulin, or a metal grid with a spacing of 0.05-0.5 mm camera Device shown in Fig.1, where the electromagnetic 3-mm sheet 8 to cover the entire inner surface 6, is pressed layer of glass wool 5 150 mm thick and placed a layer of sound-absorbing wedges 4 KPC-0.5 height 500 mm Air gap 9 between the layer of the wedges 4 and blade 7, a closing layer stadnoi length of 0.5 mm, and saksonova space of the air gap 9 and a layer of glass wool 5 make a variable thickness depending on the class of the camera from 150 to 900 mm and thick canvas or metal mesh 7 pressed glass wool to the internal surfaces of the chamber 6. The layer of glass wool is pressed against the bounding surfaces of the two parallel panels of thick fabric or metal grids with spacing of 0.05 to 0.5 mm and a separating layer of glass wool in the ratio of 1:2. When using two metal grids, they can act as an electromagnetic screen. The second variant of the absorber shown in Fig.3, where the layers of glass wool pressed against the surfaces of the electromagnetic screen of steel 3-mm sheet with holes throughout the area, placed with equal step, the diameter of which is calculated from the lower cutoff frequency of the acoustic camera.

Used books

1. OST 4.275.008-79.

2. The invention 2064559 "sound design for acoustic anechoic chambers", CL 6 E 04 1/82.

3. Copyright certificate 446898 "Resonant absorber", CL 6 G 10 K 11/00.

4. The invention 2113040, CL G 01 17/00.

1. Luggage acoustic muted rhythmic, jaklovce, electromagnetic screen and through an air gap layer of sound-absorbing wedges, characterized in that the layer of glass wool has a thickness of 150-900 mm and pressed to the walls of the steel sheet or wire mesh with a spacing of 0.05-0.5 mm, the air gap has a thickness of 10-15 mm

2. Luggage acoustic muted rhythmic under item 1, wherein the electromagnetic shield is made of two parallel layers of metal sheet thickness equal to 3 mm, with holes throughout the area, placed with equal step, and parallel to it a metal grid with a spacing of 0.05-0.5 mm, placed at a distance from the walls, not exceeding the thickness of a layer of glass wool, and dividing the thickness of the layer of glass wool in the ratio of 1: 2.

3. Luggage acoustic muted rhythmic under item 1, characterized in that the electromagnetic shield consists of two parallel layers made of a metal grid with a spacing of 0.05-0.5 mm, placed at a distance from the walls, not exceeding the thickness of a layer of glass wool, and dividing the thickness of the layer of glass wool in the ratio of 1: 2.

4. Luggage acoustic muted rhythmic according to any one of the preceding paragraphs. 1-3, characterized in that the wedges have a constant length of 500 mm

6. Luggage acoustic muted rhythmic under item 5, characterized in that the resonant absorber consists of two parallel layers of thick fabric, placed at a distance from the walls, not exceeding the thickness of a layer of glass wool, and dividing the thickness of the layer of glass wool in the ratio of 1: 2.

7. Luggage acoustic muted rhythmic under item 5 or 6, characterized in that the material of the resonant absorber is used tarpaulin.

8. Luggage acoustic muted rhythmic according to any one of the preceding paragraphs. 6 and 7, characterized in that the wedges have a constant length of 500 mm

 

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FIELD: multilayer panels with filler.

SUBSTANCE: panel has upper and lower walls and zigzag-shaped filler placed between them. Filler is trapezoid-like in cross-section, and in its recesses inserts inserted into panel are placed, profile of which matches profile of filler in cross-section.

EFFECT: higher efficiency, higher durability and lower laboriousness of manufacture.

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