Classifications

• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects

Definitions

• the invention relates to a sound absorber, in particular for motor vehicles, with a molded part made of thermoplastic material and at least one second part which delimits a cavity with the molded part.
• Such a sound absorber is known for example from DE 34 45 656 AI.
• the known sound absorber is composed of an outer foam layer made of open-cell, air-permeable foam plastic, a flat, sound-transparent stabilization layer connected to it, and a carrier layer connected to the edge and a central region of the stabilization layer.
• the stabilization layer and the support layer delimit a cavity and each consist of thermoplastic.
• the stabilization layer is provided with openings which consist of holes made from the foam side by means of a needle tool.
• This well-known sound absorber has basically proven itself in practice. However, due to its foam layer, it does not have satisfactory media resistance under certain operating conditions. Furthermore, the heat resistance of such a sound absorber is relatively limited.
• DE 298 03 675 Ul discloses various variants of a soundproofing shield with a recess or Chambered heavy layer, which is formed in particular from polyurethane, polypropylene, polyolefin elastomers (POE) or EPDM.
• the heavy layer is formed from EPDM, the chambers being each pot-shaped in cross-section, together forming a honeycomb structure and covered with a metal or aluminum foil.
• DE 195 16 819 C2 describes a sound damping device which is intended in particular for attachment to space-limiting surfaces and has a cover layer arranged at a distance from the space-limiting surface.
• the cover layer comprises a first damping element for low sound frequencies and a second damping element for high sound frequencies.
• the first damping element consists of a plate absorber in the form of a closed plastic film, the plate absorber being arranged at a distance from the space-delimiting surface by a frame-shaped spacing element made of foam, forming a cavity.
• the second damping element on the other hand, consists of a porous foam absorber, which is arranged on the plate absorber and connected to the entire surface thereof.
• the object of the present invention is to modify a sound absorber of the type mentioned at the outset in such a way that it has good media resistance and a higher heat resistance with the same or improved acoustic effectiveness.
• the sound absorber according to the invention is thus essentially made of one Molded part made of thermoplastic and at least one second part, which delimits a cavity with the molded part, wherein a plurality of pin-shaped or mandrel-shaped spacers protruding into the cavity and directed towards the second part is formed on the molded part.
• the molded part has a plurality of depressions on the outside, each of which extends into a spacer.
• the latter has good media resistance.
• Particularly good media resistance and temperature resistance can be achieved if the molded part is produced by deep-drawing a polyester film, in particular a PET film (polyethylene terephthalate film).
• PET film polyethylene terephthalate film
• the spacers ensure that the distance between the molded part and the second part and thus the cavity delimited between the two parts does not change, or at most only slightly, at high ambient temperatures or the effects of heat.
• the shape of the foam layer often changes due to temperature or heat, in particular if the foam layer consists of PP foam (polypropylene foam).
• the molded part of the sound absorber according to the invention is flexible, has a certain mass and is. stimulated to resonate by sound waves hitting it. Part of the sound energy is converted into heat.
• the one between the molded part and the second Part of the absorber existing air-filled cavity acts as an elastic spring.
• the sound absorber according to the invention thus represents a spring-mass system.
• the recesses formed on the outside of the molded part are acoustically effective since at least some of the sound waves impinging on the sound absorber penetrate into the recesses and allow the air contained therein to oscillate back and forth. Part of the sound energy is converted into heat due to friction effects. Compared to a corresponding sound absorber without such depressions, the volume of the cavity of the sound absorber according to the invention and thus its overall height can be reduced with the same acoustic power (effectiveness).
• the spacers are pin-shaped or mandrel-shaped and are therefore relatively small and compact. They hardly reduce the acoustically effective volume of the air-filled cavity of the sound absorber, even if they are formed on the molded part in a relatively large number. For example, more than 150, preferably more than 180 spacers per square decimeter can be formed on the molded part.
• the second part of the absorber according to the invention which delimits the air-filled cavity is preferably formed from a heavy layer, a non-woven layer, a foam layer and / or a textile layer.
• the second part can in particular also be constructed in multiple layers, for example from a heavy mat and a further absorber layer made of non-woven material, foam or textile material.
• the molded part is preferably cassette or shell-shaped, the depth of the cassette or shell preferably being greater than the respective length of the spacers.
• the second part for example a heavy mat, can then be inserted into the molded part and be flush with the rear edge of the molded part. As a result, the second part and the cavity can be protected from contamination by dust or the like.
• the molded part has a circumferential fastening flange.
• the sound absorber according to the invention can then be attached in a simple manner to body parts and machine parts, for example using screws, rivets, clamps or adhesives.
• FIG. 1 is a cross-sectional view of a sound absorber according to the invention
• FIG. 2 is a plan view of the outside of the sound absorber according to FIG. 1, 3 is a plan view of the outside of a sound
• FIG. 4 shows a cross-sectional view of a sound absorber according to the invention in accordance with a third exemplary embodiment
• Fig. 5 is a cross-sectional view of a sound absorber according to the invention according to a fourth embodiment.
• the sound absorber according to the invention is constructed from a molded part 1 and at least one further acoustically active part 2.
• the second part 2 is a heavy mat, preferably made of recycled material.
• sound absorber materials such as nonwovens, foams and acoustically effective textile mats can also be attached to the rear of the molded part 1.
• the molded part 1 is made of thermoplastic material and was produced by deep-drawing a corresponding air-impermeable plastic film.
• the plastic film is a polyester film, preferably a PET film.
• the molded part 1 is essentially cassette or shell-shaped and has a circumferential fastening flange 3 (cf. FIG. 2).
• the fastening flange 3 can be provided with holes (not shown) which serve to connect screws, rivets, clamps, fastening knobs or adhesives to the molded part 1.
• a plurality of spacers 4 are formed, which are essentially mandrel-shaped and are formed by means of a molding tool having needle-shaped pins or the like.
• the molded part 1 has a plurality of depressions 6 on its exposed outside 5, each of which extends into a spacer 4.
• the spacers 4 and depressions 6 are preferably produced during the deep-drawing of the molded part 1. However, it is also possible to produce the spacers in a subsequent operation after deep-drawing the cassette-shaped molded part 1. It can be seen that the average outer diameter of the spacers 4 is smaller than their average length.
• the cassette-shaped molded part 1 and the heavy mat as the second part 2 of the sound absorber delimit a cavity 7.
• the spacers 4 protrude into the air-filled cavity 7 and are directed towards the heavy mat 2.
• the depressions 6 are closed towards the cavity 7.
• the spacers 4 are of substantially the same length and extend to the heavy mat 2.
• the depth of the molded part 1 is greater than the respective length of the spacers 4, so that the heavy mat 2 is also included in the molded part 1.
• the depth of the molded part 1 and the length or height of the spacers 4 are dimensioned such that the rear side 8 of the heavy mat 2 is essentially flush with the rear side (contact surface) of the fastening flange.
• the spacers 4 are of essentially uniform design, since they have essentially the same length or height and essentially the same average outside diameter. Likewise, the depressions 6 formed in the spacers 4 have essentially the same depth and essentially the same average inner diameter. Furthermore, the spacers 4 and the depressions 6 are formed evenly distributed over the surface of the molded part 1, as shown in particular in FIG. 2.
• the acoustic effectiveness of the sound absorber according to the invention can be improved under appropriate operating conditions if the spacers 4 and depressions 6, as shown schematically in FIG. 3, are formed unevenly distributed over the surface of the molded part 1. Furthermore, it can be advantageous if the depressions 6 have different inner diameters (cf. also FIG. 3).
• Another possibility to improve the acoustic effectiveness of the sound absorber according to the invention is to make the spacers 4 of different lengths and / or the recesses 6 of different depths. Areas with spacers 4 of different lengths can be formed on the molded part 1, the spacers 4 each having the same length in the different regions. Accordingly, regions with depressions 6 of different depths are also formed on the molded part 1, as in FIG. 5 is shown schematically.
• the second part 2 which in turn is, for example, a heavy mat or a foam sheet, has 4 regions of different thicknesses corresponding to the length or height profile of the spacers.
• the exemplary embodiment shown in FIG. 4 differs from the exemplary embodiment according to FIG. 1 in that a nonwoven layer 9 is first inserted into the cassette-shaped molded part 1, which lies against the tips of the spacers 4.
• the nonwoven layer 9 is followed by a second layer 2, in the form of a heavy mat or a foam layer, the back 8 of which in turn is flush with the fastening flange 3.

Applications Claiming Priority (3)

Publications (1)

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ID=29414314

Family Applications (1)

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• 2002
  • 2002-06-25 DE DE10228395A patent/DE10228395C1/de not_active Expired - Fee Related
• 2003
  • 2003-06-25 CN CN038148609A patent/CN1662953A/zh active Pending
  • 2003-06-25 MX MXPA04012835A patent/MXPA04012835A/es not_active Application Discontinuation
  • 2003-06-25 US US10/519,265 patent/US20050241877A1/en not_active Abandoned
  • 2003-06-25 WO PCT/EP2003/006713 patent/WO2004001718A1/de active Application Filing
  • 2003-06-25 BR BRPI0312049-0A patent/BR0312049A/pt unknown
  • 2003-06-25 AU AU2003278247A patent/AU2003278247A1/en not_active Abandoned
  • 2003-06-25 EP EP03740341A patent/EP1516318A1/de not_active Withdrawn
  • 2003-06-25 JP JP2004514861A patent/JP2005531022A/ja active Pending
• 2004
  • 2004-12-14 ZA ZA200410073A patent/ZA200410073B/en unknown

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