EP0798694B1 - Cleanable low frequency sound attenuator - Google Patents

Cleanable low frequency sound attenuator Download PDF

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Publication number
EP0798694B1
EP0798694B1 EP97104736A EP97104736A EP0798694B1 EP 0798694 B1 EP0798694 B1 EP 0798694B1 EP 97104736 A EP97104736 A EP 97104736A EP 97104736 A EP97104736 A EP 97104736A EP 0798694 B1 EP0798694 B1 EP 0798694B1
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Prior art keywords
cleanable
chambers
sound attenuator
cleaning
attenuator according
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German (de)
French (fr)
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EP0798694A2 (en
EP0798694A3 (en
Inventor
Helmut Dr. Prof. Fuchs
Peter Dipl.-Ing. Brandstätt
Markus Dipl.-Ing. Heizmann
Dietmar Dr. Eckoldt
Norbert Rambausek
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Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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    • 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 cleanable silencer for low frequencies.
  • Chamber silencer (SD), e.g. DE 23 21 549 C2, are known from the principle of action. So a broadband effect of the Lambda quarter or the Helmholtz resonators SD is achieved, are built into these porous absorbers.
  • these porous absorbers are glass or mineral wool, generally expressed silicate fibrous porous absorber, or metal wool, mostly stainless steel wool.
  • This porous Absorbers lose their acoustic properties with media that contain dirt, because the dirt protects the protective layers from the porous absorber (Perforated sheets, fleeces, glass silk fabric) and / or the porous absorber itself. If the acoustically effective cavities are closed by dirt, the SD loses some of its effectiveness and must be cleaned or replaced become.
  • DE-A-2 821 069 discloses a silencer for exhaust air in Industrial equipment with a washing device for the surfaces is arranged by silencers.
  • the invention avoids these disadvantages.
  • the object of the invention is therefore a create easily cleanable silencers according to the generic term.
  • the SD with the same cross-section is installed over a length L or the SD is attached to one end of the channel.
  • the cross section is generally constant over the entire length of the SD so that the pressure loss of the SD compared to the flowing gas remains as small as possible.
  • the inner channel 2 of the SD guiding the flow is interrupted by channel pieces 3 executed in perforated sheet metal.
  • the geometry of these perforated sheets is an acoustically and aerodynamically relevant parameter of the SD. It can be changed by the size of the perforated plate, the proportion of perforated area, the hole diameter and the material thickness of the perforated plate.
  • hollow chambers 4 Due to the perforated wall of the inner channel, externally attached hollow chambers 4 are acoustically coupled to the inner channel 2, but at the same time are separated from the latter in terms of flow technology.
  • the acoustic parameters of these hollow chambers 4 are their length (in the axial direction) and their thickness (perpendicular to the axial direction). Because the chambers do not absorb broadband due to their geometry, several of them must be arranged one behind the other in the axial direction in such a way that a damping which is adapted to the acoustic requirements is achieved, which can also be broadband.
  • Figure 2 shows an example of the insertion loss of a 4 m determined according to the standard long tube SD with 400 mm diameter of the inner tube.
  • the chambers 4 and the perforated plates 3 can be cleaned.
  • the chamber is not acoustically coupled to the channel conducting the medium via a thin wall with a plurality of openings, but rather via only one opening.
  • the wall can also be thick .
  • the thickness is an acoustic design parameter. Large wall thicknesses can occur, for example, in SD for tunnel exhaust air and supply air systems, in which the ducts can be bricked or made of concrete. So far, the greatest wall thickness of 5 mm has been made in sheet steel.
  • the openings have to be at a distance of one quarter of the wavelength of the frequencies to be attenuated.
  • the cleanable silencer according to the invention differs significantly from the prior art because the spacing of the openings can be freely selected.
  • the cleaning media 8 air, gas, steam, water, cleaning agents
  • the chambers above as shown in Figure 1 or in the chambers or pipelines located in the inner channel.
  • Sieve-like outlets can also be used instead of nozzles as line ends, which open into the chambers 4, can be provided. At the line ends, too movable nozzles, e.g. according to the lawn sprinkler principle or also based on the principle for sprinklers.
  • gaseous cleaning agents e.g.

Abstract

The channel (1) contains perforated pieces (3) of different lengths. These are connected with chambers (4) outside the channel which form sound absorbers. The channels and or pieces are made of sheet metal, plastics, concrete or brick. The chambers can be cleaned periodically or continuously by fixed or movable nozzles (9). The chambers are connected with pipes (8) for cleaning agent via valves or other adjustments (7).

Description

Die Erfindung betrifft einen reinigbaren Schalldämpfer für tiefe Frequenzen.The invention relates to a cleanable silencer for low frequencies.

Stand der TechnikState of the art

Kammer-Schalldämpfer (SD), z.B. DE 23 21 549 C2, sind vom Wirkprinzip her bekannt. Damit eine breitbandige Wirkung der Lambda-Viertel- oder der Helmholtz-Resonatoren-SD erzielt wird, werden in diese poröse Absorber eingebaut. Dem Stand der Technik entsprechend sind das Glas- oder Mineralwollen, allgemein ausgedrückt silikatische faserige poröse Absorber, oder Metallwollen, meist Edelstahlwolle. Diese porösen Absorber verlieren bei Medien, die Schmutz enthalten, ihre akustischen Eigenschaften, weil der Schmutz die Schutzschichten vor dem porösen Absorber (Lochbleche, Vliese, Glasseidengewebe) und/oder den porösen Absorber selbst zusetzt. Wenn die akustisch wirksamen Hohlräume durch Schmutz verschlossen werden, verliert der SD einen Teil seiner Wirkung und muß gereinigt werden bzw. erneuert werden. Die Reinigung ist deshalb problematisch, weil entweder faserförmige Absorber dabei ausgetragen werden oder die Reinigung nicht über die gesamte Absorberdicke erfolgreich verläuft. Erfahrungsgemäß läßt die akustische Wirksamkeit solcher dem Stand der Technik entsprechender SD mit der Betriebsstunden-Zahl (Verschmutzung) und der Zahl der durchgeführten Reinigungen nach. Außerdem gibt es andere (technologische) Nachteile je nach Art der Verschmutzung (z.B. Brand- und Explosionsgefahr).Chamber silencer (SD), e.g. DE 23 21 549 C2, are known from the principle of action. So a broadband effect of the Lambda quarter or the Helmholtz resonators SD is achieved, are built into these porous absorbers. The state of the According to technology, these are glass or mineral wool, generally expressed silicate fibrous porous absorber, or metal wool, mostly stainless steel wool. This porous Absorbers lose their acoustic properties with media that contain dirt, because the dirt protects the protective layers from the porous absorber (Perforated sheets, fleeces, glass silk fabric) and / or the porous absorber itself. If the acoustically effective cavities are closed by dirt, the SD loses some of its effectiveness and must be cleaned or replaced become. Cleaning is problematic because either fibrous absorbers are carried out or the cleaning is not over the entire absorber thickness successful. Experience has shown that the acoustic effectiveness of such state of the art SD with the number of operating hours (Pollution) and the number of cleaning operations carried out. Also there there are other (technological) disadvantages depending on the type of pollution (e.g. fire and Explosion).

In Kanälen mit rundem oder eckigem Querschnitt werden Medien (Gase) gefördert, die neben Lärm auch Verschmutzungen transportieren. Diese Verschmutzungen reichern sich mit der Zeit an herkömmlichen SD-Einbauten an deren akustisch aktiver Oberfläche und im (porösen) akustisch wirksamen Material (Absorber) so stark an, daß die akustische Wirksamkeit verlorengeht.Media (gases) are conveyed in channels with a round or square cross-section transport pollution in addition to noise. This pollution enriches Over time, conventional SD fixtures on their acoustically active surface and in the (porous) acoustically active material (absorber) so strongly that the acoustic effectiveness is lost.

DE-A-2 821 069 offenbart einen Schalldämpfer für Abluft in Industrieanlagen bei dem eine Waschvorrichtung für die Oberflächen von Schalldämpferkulissen angeordnet ist. DE-A-2 821 069 discloses a silencer for exhaust air in Industrial equipment with a washing device for the surfaces is arranged by silencers.

Die Erfindung vermeidet diese Nachteile. Aufgabe der Erfindung ist es daher, einen leicht reinigbaren Schalldämpfer gemäß Oberbegriff zu schaffen.The invention avoids these disadvantages. The object of the invention is therefore a create easily cleanable silencers according to the generic term.

Erfindungsgemäß wird dies erreicht durch einen Schalldämpfer nach Anspruch 1. Vorteilhafte Ausgestaltungen sind Gegenstand der Unteransprüche.According to the invention this is achieved by a silencer according to claim 1. Advantageous refinements are the subject of the dependent claims.

Die Erfindung ist ein von Haus aus gegen Verschmutzung unempfindlicher SD, der keinerlei akustisch wirksames poröses Absorptionsmaterial enthält. Er kann zusätzlich mit einer mit Gas und/oder Flüssigkeit betriebenen Reinigungsanlage versehen werden, ohne daß sich seine akustischen Eigenschaften dadurch verschlechtern. Dabei ist es möglich,

  • a) die einzelnen Teil des SD getrennt zu reinigen,
  • b) die Teile des SD gleichzeitig zu reinigen,
  • c) die Reinigung periodisch durchzuführen oder
  • e) auf eine Reinigung während des Betriebes der Anlage oder während Abstellzeiten im Einbauzustand des SD ganz zu verzichten und diesen bei Bedarf auszubauen, zu reinigen und dabei wieder einzubauen.
    • The invention is an inherently insensitive to pollution SD, which contains no acoustically effective porous absorption material. It can also be equipped with a gas and / or liquid operated cleaning system without impairing its acoustic properties. It is possible
  • a) to clean the individual parts of the SD separately,
  • b) cleaning the parts of the SD at the same time,
  • c) carry out the cleaning periodically or
  • e) to dispense with cleaning during the operation of the system or during downtime in the installed state of the SD and to remove, clean and reinstall it if necessary.

    • Anhand von Bild 1 soll die Wirksamkeit des SD erläutert werden:
    In dem (runden oder eckigen) Kanal 1 wird über eine Länge L der SD mit gleichem Querschnitt eingebaut oder der SD wird an ein Kanalende angebaut. Der Querschnitt ist über die gesamte Länge des SD im allgemeinen konstant, damit der Druckverlust des SD gegenüber dem strömenden Gas möglichst gering bleibt. Der innere die Strömung führende Kanal 2 des SD wird durch in Lochblech ausgeführte Kanalstücke 3 unterbrochen. Die Geometrie dieser Lochbleche ist ein akustisch und aerodynamisch relevanter Parameter des SD. Er ist durch die Größe des Lochbleches, den Lochflächenanteil, die Lochdurchmesser und die Materialstärke des Lochbleches veränderbar. Durch die gelochte Wandung des inneren Kanals werden außen angebrachte Hohlkammern 4 akustisch an den inneren Kanal 2 angekoppelt, aber gleichzeitig strömungstechnisch von diesem getrennt. Die akustischen Parameter dieser Hohlkammern 4 sind ihre Länge (in Achsrichtung) und ihre Dicke (senkrecht zur Achsrichtung). Weil die Kammern auf Grund ihrer Geometrie nicht breitbandig absorbieren, müssen mehrere von ihnen so in Achsrichtung hintereinander angeordnet werden, daß eine den akustischen Erfordernissen angepaßte Dämpfung erreicht wird, die auch breitbandig sein kann.     The effectiveness of the SD should be explained on the basis of Figure 1:
    In the (round or square) channel 1, the SD with the same cross-section is installed over a length L or the SD is attached to one end of the channel. The cross section is generally constant over the entire length of the SD so that the pressure loss of the SD compared to the flowing gas remains as small as possible. The inner channel 2 of the SD guiding the flow is interrupted by channel pieces 3 executed in perforated sheet metal. The geometry of these perforated sheets is an acoustically and aerodynamically relevant parameter of the SD. It can be changed by the size of the perforated plate, the proportion of perforated area, the hole diameter and the material thickness of the perforated plate. Due to the perforated wall of the inner channel, externally attached hollow chambers 4 are acoustically coupled to the inner channel 2, but at the same time are separated from the latter in terms of flow technology. The acoustic parameters of these hollow chambers 4 are their length (in the axial direction) and their thickness (perpendicular to the axial direction). Because the chambers do not absorb broadband due to their geometry, several of them must be arranged one behind the other in the axial direction in such a way that a damping which is adapted to the acoustic requirements is achieved, which can also be broadband.

    Bild 2 zeigt beispielshaft die nach Norm bestimmte Einführungsdämpfung eines 4 m langen Rohr-SD mit 400 mm Durchmesser des Innenrohres.Figure 2 shows an example of the insertion loss of a 4 m determined according to the standard long tube SD with 400 mm diameter of the inner tube.

    Weil diese Hohlkammern-SD kein Absorptionsmaterial wie der Stand der Technik enthalten, ist eine Reinigung der Kammern 4 und der Lochbleche 3 möglich. Außerdem wird im erfindungsgemäßen reinigbaren SD die Kammer nicht über eine dünne Wand mit mehreren Öffnungen akustisch an den das Medium leitenden Kanal angekoppelt, sondern über nur eine Öffnung. Die Wand kann auch dick sein. Die Dicke ist akustischer Auslegungs-Parameter. Große Wandstärken können z.B. in SD für Tunnel-Abluft- und Zuluftanlagen auftreten, in denen die Kanäle gemauert oder aus Beton hergestellt sein können. In Stahlblech wurde bisher die größte Wand-Dicke mit 5 mm ausgeführt. Weiterhin müssen nach dem Stand der Erfindung die Öffnungen zueinander einen Abstand von einem Viertel der Wellenlänge der zu bedämpfenden Frequenzen haben. Auch hier unterscheidet sich der erfindungsgemäße reinigbare Schalldämpfer wesentlich vom Stand der Technik, weil die Abstände der Öffnungen frei wählbar sind.Because these hollow chamber SDs do not contain any absorption material like the prior art, the chambers 4 and the perforated plates 3 can be cleaned. In addition, in the cleanable SD according to the invention, the chamber is not acoustically coupled to the channel conducting the medium via a thin wall with a plurality of openings, but rather via only one opening. The wall can also be thick . The thickness is an acoustic design parameter. Large wall thicknesses can occur, for example, in SD for tunnel exhaust air and supply air systems, in which the ducts can be bricked or made of concrete. So far, the greatest wall thickness of 5 mm has been made in sheet steel. Furthermore, according to the prior art, the openings have to be at a distance of one quarter of the wavelength of the frequencies to be attenuated. Here, too, the cleanable silencer according to the invention differs significantly from the prior art because the spacing of the openings can be freely selected.

    Für die Reinigung werden die Reinigungsmedien 8 /Luft, Gas, Dampf, Wasser, Reinigungsmittel) den Kammern über außen (wie im Bild 1 dargestellt) oder in den Kammern oder im inneren Kanal liegende Rohrleitungen zugeführt. In den Kammern können radial oder tangential oder in beliebigem Winkel ausströmende, z.B. düsenförmige Öffnungen 9 das Reinigungs-Medium 8 gleichmäßig oder gezielt in die Kammern eindringen lassen. Es können auch siebähnliche Auslässe statt Düsen als Leitungsenden, die in den Kammern 4 münden, vorgesehen sein. An den Leitungsenden können auch bewegliche Düsen angeordnet sein, z.B. nach dem Rasensprengerprinzip oder auch nach dem Prinzip für Sprinkler. Bei gasförmigen Reinigungsmitteln (z.B. Druckluft) und staubförmigen, sich nicht verfestigenden Ablagerungen in den Kammern, kann auf eine Entsorgungsleitung 6 verzichtet werden. Der aufgewirbelte Staub tritt dann durch die Lochbleche in den inneren Kanal ein und wird dort mit dem Gasstrom aus dem Bereich des SD hinausbefördert. Das gleiche gilt, wenn der SD ständig mit einem Spülgas über die Reinigungsleitung 5 mit einem geringen Überdruck in den Kammern gegenüber dem Innen-Kanal 2 versehen wird, so daß in den Löchern der Lochbleche stets eine geringe Strömung von außen nach innen herrscht, so daß Schmutzpartikel nicht in die Löcher oder über diese in die Kammern 4 eindringen können. Werden kondensierender Dampf und/oder Reinigungs-Flüssigkeiten über die Reinigungsleitungen 5 den Kammern 4 zugeführt, kann auf die Entsorgungsleitung 6 nur in den Fällen verzichtet werden, in denen die SD senkrecht angeordnet sind und die Lochbleche 3 sich an den unteren Enden der Kammern 4 befinden, so daß die verschmutzte Reinigungsflüssigkeit durch die Löcher nach unten in den Kanal 1 laufen und dort entsorgt werden kann. Die Reinigung der Kammern wird entweder für jede einzeln über die Ventile 7 oder gruppenweise oder gleichzeitig über alle Kammern vorgenommen.For cleaning, the cleaning media 8 (air, gas, steam, water, cleaning agents) the chambers above (as shown in Figure 1) or in the chambers or pipelines located in the inner channel. Can in the chambers radially or tangentially or at any angle, e.g. nozzle-shaped Openings 9 penetrate the cleaning medium 8 evenly or specifically into the chambers to let. Sieve-like outlets can also be used instead of nozzles as line ends, which open into the chambers 4, can be provided. At the line ends, too movable nozzles, e.g. according to the lawn sprinkler principle or also based on the principle for sprinklers. With gaseous cleaning agents (e.g. compressed air) and Dust-like, non-solidifying deposits in the chambers can a disposal line 6 can be dispensed with. The whirled up dust then passes through the perforated plates in the inner channel and is there with the gas flow from the Transported out of the area of the SD. The same applies if the SD is constantly with one Purge gas via the cleaning line 5 with a slight excess pressure in the chambers is provided opposite the inner channel 2, so that in the holes of the perforated plates There is always a small flow from the outside in, so that dirt particles cannot penetrate into the holes or through them into the chambers 4. Become more condensing Steam and / or cleaning liquids via the cleaning lines 5 fed to the chambers 4, can only on the disposal line 6 in the cases be dispensed with in which the SDs are arranged vertically and the perforated plates 3 are located at the lower ends of the chambers 4, so that the dirty Run cleaning liquid through the holes down into channel 1 and there can be disposed of. The cleaning of the chambers is either done individually for each via the valves 7 or in groups or simultaneously over all chambers performed.

    Vorteile des erfindungsgemäßen reinigbaren Kanal-SD sind

    • breitbandige, berechenbare Wirksamkeit, auch bei tiefen Frequenzen, siehe Bild 2,
    • einfacher und kostengünstiger Aufbau. Der SD kann auch nur aus einem Material gefertigt sein, so daß er nach Gebrauch ohne Probleme rückgeführt werden kann.
    • Materialwahl nach den Anforderungen aus dem Medium, z.B. Stahl, Leichtmetall, Edelstahl, Kunststoff, Glas, sowohl für die SD als auch für die Reinigungsanlage.
    • Druckverlust gegenüber der gleich langen Rohrleitung ohne SD ist vernachlässigbar. Im Rohr-SD-Prüfstand des Fraunhofer-Instituts für Bauphyik konnte der Druckverlust des in Bild 2 gezeigten SD wegen Geringfügigkeit nicht bestimmt werden.
    • Anregung der Kammern 4 durch Wirbel-Ablösung zu tonalen Komponenten (Orgelpfeifen-Effekt) wird durch die Lochblech-Abdeckung 3 der Öffnungen zwischen innerem Kanal 2 und den außen angeordneten Kammern 4 vermieden.
    • Die SD können in Kanäle aller Druckstufen eingebaut werden, wenn sie entsprechend dicht gefertigt und als Druckgefäße ausgelegt werden.
    • Die SD können, ähnlich wie Kulissen-SD, nach allen Richtungen zu größeren Einheiten zusammengefügt werden, um entsprechend hohe Gas-Durchsätze zu gewährleisten, oder auch einzeln parallel zueinander betrieben werden.
    • Durch optimierte Düsenanordnung (auch Mehrfachdüsen) läßt sich ein hoher Reinigungsgrad erzielen.
    • Der konstruktiven Vielfalt der Kammer-Anordnungen sind kaum Grenzen gesetzt.
      Bild 3 zeigt, wie bei geringer zur Verfügung stehender SD-Länge die Kammern so angeordnet werden können, daß der SD kurz und dafür dick wird.
    Advantages of the cleanable channel SD according to the invention are
    • broadband, predictable effectiveness, even at low frequencies, see Figure 2,
    • simple and inexpensive construction. The SD can also be made from only one material so that it can be easily returned after use.
    • Material selection according to the requirements from the medium, e.g. steel, light metal, stainless steel, plastic, glass, both for the SD and for the cleaning system.
    • Pressure loss compared to the same length of pipe without SD is negligible. In the pipe SD test rig of the Fraunhofer Institute for Building Physics, the pressure loss of the SD shown in Figure 2 could not be determined due to its insignificance.
    • Excitation of the chambers 4 by detachment of the vertebrae to tonal components (organ pipe effect) is avoided by the perforated sheet cover 3 of the openings between the inner channel 2 and the chambers 4 arranged on the outside.
    • The SD can be installed in ducts of all pressure levels if they are made appropriately sealed and designed as pressure vessels.
    • The SDs can be combined in all directions to form larger units, in order to ensure correspondingly high gas throughputs, or can be operated individually in parallel with one another.
    • A high degree of cleaning can be achieved through optimized nozzle arrangement (also multiple nozzles).
    • There are hardly any limits to the structural variety of the chamber arrangements.
      Figure 3 shows how the chambers can be arranged in such a way that the SD is short and therefore thick with a short SD length.

    Literatur:Literature:

  • 1) Brandstätt, P.; Eckoldt, D.; Heizmann, M.; Rambausek, N.: Rohrschalldämpfer für tiefe Frequenzen. IBP-Mitteilungen (Entwurf)1) Brandstätt, P .; Eckoldt, D .; Heizmann, M .; Rambausek, N .: Pipe silencer for low frequencies. IBP releases (draft)
  • 2) Leistner, Ph.; Krüger, J.; Leistner, M.: Hybride Schalldämpfer - Hohe Dämpfung bei tiefen Frequenzen. Zur Veröffentlichung vorgesehen in: Heizung Lüftung/Klima Haustechnik.2) Leistner, Ph .; Kruger, J .; Leistner, M .: Hybrid silencers - high attenuation at low frequencies. For release provided in: heating ventilation / air conditioning building services.
  • 3) Heizmann, Markus: Mineralwollefreier Rohr-Schalldämpfer für tiefe Frequenzen. Diplomarbeit an der Fachhochschule Stuttgart - Hochschule für Technik, 1995.3) Heizmann, Markus: Mineral wool-free pipe silencer for low frequencies. Diploma thesis the Stuttgart University of Applied Sciences - University of Applied Sciences, 1995.

    • Claims (10)

    1. Cleanable sound attenuator for low frequencies, characterised in that
      perforated duct sections (3) are provided in a duct (1) and the duct sections (3) are configured with different lengths,
      the duct sections (3) connect with chambers (4) disposed externally on the duct (1) and the chambers are configured as sound attenuators,
      fixed or movable nozzles (9) are provided in the chambers for cleaning the chambers (4),
      and the chambers (4) connected to cleaning agent pipes (8) via controllable valves or other final control elements, e.g. rotary slide valves (7).
    2. Cleanable sound attenuator according to Claim 1, characterised in that the duct sections (3) are also configured to be individually cleanable.
    3. Cleanable sound attenuator according to Claim 1, characterised in that cleaning may be conducted continuously or periodically.
    4. Cleanable sound attenuator according to one of Claims 1 - 3, characterised in that the ducts (1) and/or duct sections (3) are made of sheet metal, plastic or other solid materials such as concrete or masonry.
    5. Cleanable sound attenuator according to one of Claims 1 - 4, characterised in that the wall thickness of the chambers (4) is defined as a function of the acoustic parameters.
    6. Cleanable sound attenuator according to one of Claims 1 - 5, characterised in that the lengths of the chambers (4) are configured according to the quarter-wave principle or Helmholtz principle.
    7. Cleanable sound attenuator according to Claim 1, characterised in that the cleaning installations (5 - 9) are fixedly installed or configured to be transportable.
    8. Cleanable sound attenuator according to Claim 1, characterised in that the chambers (4) are acoustically connected to one another via the cleaning pipes (5 and 6).
    9. Cleanable sound attenuator according to Claim 1, characterised in that the cleaning pipes (5 and 6) are acoustically sealed by the final control elements (7).
    10. Cleanable sound attenuator according to Claims 1 - 9, characterised in that the cross-sections are of any desired shape (round, rectangular, polygonal) and may be combined as desired, e.g. duct (1) and inner duct (2) square, chambers (4) round on the outside.
    EP97104736A 1996-03-29 1997-03-20 Cleanable low frequency sound attenuator Expired - Lifetime EP0798694B1 (en)

    Applications Claiming Priority (2)

    Application Number Priority Date Filing Date Title
    DE19612572A DE19612572A1 (en) 1996-03-29 1996-03-29 Cleanable silencer for low frequencies
    DE19612572 1996-03-29

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    EP0798694A2 EP0798694A2 (en) 1997-10-01
    EP0798694A3 EP0798694A3 (en) 2000-03-01
    EP0798694B1 true EP0798694B1 (en) 2003-08-13

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    AT (1) ATE247324T1 (en)
    DE (2) DE19612572A1 (en)

    Cited By (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    EP0798965B2 (en) † 1994-12-23 2007-08-15 Cadbury Schweppes Plc Process for manufacture of reduced fat chocolate

    Families Citing this family (2)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE19861018C2 (en) 1998-12-15 2001-06-13 Fraunhofer Ges Forschung Controlled acoustic waveguide for sound absorption
    DE102005014419B3 (en) * 2005-03-24 2006-08-03 Studt & Co (Gmbh & Co) Device for sound proofing of flowing, gaseous media has partition wall, which is adjustably formed for fixing of different volume areas in the body

    Family Cites Families (7)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE580923C (en) * 1930-11-05 1933-07-19 Gabriel Becker Muffler for internal combustion engines through acoustic filters
    FR873027A (en) * 1940-07-29 1942-06-26 Eberspaecher J Device for damping noise in pipes
    DE1476629A1 (en) * 1963-03-22 1969-07-10 Walker Manufact Company Exhaust and sound insulation system for motor vehicles and the like.
    US3776364A (en) * 1972-04-28 1973-12-04 Donaldson Co Inc Noise reduction apparatus and method
    DE2821069B1 (en) * 1978-05-13 1979-06-28 Kaefer Isoliertechnik Silencer for exhaust air from industrial plants
    DE3807680A1 (en) * 1988-03-09 1989-09-21 Jehle Norbert Silencer not sensitive to soiling
    DE9400428U1 (en) * 1994-01-14 1994-04-07 Gillet Heinrich Gmbh Device for reducing resonance effects in pipes

    Cited By (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    EP0798965B2 (en) † 1994-12-23 2007-08-15 Cadbury Schweppes Plc Process for manufacture of reduced fat chocolate

    Also Published As

    Publication number Publication date
    DE59710558D1 (en) 2003-09-18
    DE19612572A1 (en) 1997-10-02
    EP0798694A2 (en) 1997-10-01
    EP0798694A3 (en) 2000-03-01
    ATE247324T1 (en) 2003-08-15

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