EP0664044B1 - Caisson actif reduisant la transmission acoustique - Google Patents

Caisson actif reduisant la transmission acoustique Download PDF

Info

Publication number
EP0664044B1
EP0664044B1 EP93904473A EP93904473A EP0664044B1 EP 0664044 B1 EP0664044 B1 EP 0664044B1 EP 93904473 A EP93904473 A EP 93904473A EP 93904473 A EP93904473 A EP 93904473A EP 0664044 B1 EP0664044 B1 EP 0664044B1
Authority
EP
European Patent Office
Prior art keywords
noise
error
actuator
container
controller
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93904473A
Other languages
German (de)
English (en)
Other versions
EP0664044A4 (fr
EP0664044A1 (fr
Inventor
Chris Fuller
Michael Mcloughlin
Steve Hildebrand
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NCT Group Inc
Original Assignee
NCT Group Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NCT Group Inc filed Critical NCT Group Inc
Priority claimed from PCT/US1992/008401 external-priority patent/WO1994009484A1/fr
Publication of EP0664044A1 publication Critical patent/EP0664044A1/fr
Publication of EP0664044A4 publication Critical patent/EP0664044A4/fr
Application granted granted Critical
Publication of EP0664044B1 publication Critical patent/EP0664044B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Definitions

  • the present invention relates generally to noise or sound control and more particularly to the control of radiated sound from vibrating machinery by enclosing the machinery in what is termed an "active box or container".
  • the purpose of the active box is to markedly reduce the radiation of the sound from the machine to observation points in the surrounding field, with a very lightweight, compact, non-airtight structure.
  • the airtight condition implies that it would be extremely difficult to build an effective high TL container for applications which require air flow (e.g. a.c. units, compressors, etc.) or piping and wiring connections or ventilation for cooling. These requirements would imply significant holes through which the acoustic energy could leak.
  • air flow e.g. a.c. units, compressors, etc.
  • piping and wiring connections or ventilation for cooling e.g. a.c. units, compressors, etc.
  • control inputs can be in the form of point force shakers or surface strain devices, such as piezoelectric elements, bonded to the surface of the structure.
  • variable to be minimized has to be the radiated sound from the panel, measured, for example, by error microphones located in the radiated sound field as in Fuller.
  • the controller format can be any control approach which adjusts the oscillating voltage inputs to the piezoelectric inputs, for example, in order to minimize the radiated sound observed at the error microphones.
  • PVDF Polyvinylidene fluoride
  • Clark and Fuller demonstrates attenuations of the order of 20 dB of sound radiated from panels in the low frequencies (f ⁇ 600 Hz) with only one or two active actuator inputs.
  • Patent Specification No. WO 81/01479 is provided with a reference signal or waveform generator which controls a vibrator for injecting noise cancellation signals into the oil.
  • Sensing means for feeding signals to the generator are located on the transformer tank. Again, no account is taken of noise present in the far field outside the transformer tank.
  • an active noise reduction system as defined by the appended claim 1.
  • Figure 1 is a schematic of a typical box (in this case rectangular) surrounding a noisy machine.
  • the active inputs, error microphones and PVDF film as discussed above are shown. Also demonstrated is an air gap in the box side wall.
  • Figure 1 is a typical general controller arrangement used to derive the correct active control signal, using microphones as error sensors.
  • Figure 3 is a typical general controller arrangement used to derive the correct active control signal using PVDF film as an error sensor.
  • Figure 4 is a schematic of the use of panels to surround a noisy structure.
  • Figure 5 is an azimuth plot of typical noise radiation from an enclosure with and without active control.
  • Figure 6 shows a typical noise spectrum at a selected error microphone with and without control. This result shows control of broadband or multiple frequencies simultaneously.
  • FIG. 1 an example configuration of the active acoustic transmission loss box is shown in Figure 1 as 10.
  • a machine 11 is operating and radiating unwanted noise inside the box.
  • the machine requires some air flow for cooling etc. as well as piping and electrical connections and an air gap 23 can be provided.
  • the machine In order to control the sound radiation the machine is surrounded by an enclosure, in this case a rectangular box 12.
  • the box 12 is resting on the machine support base 13 but also could totally surround it. Damping or absorptive materials can also be added to the box to attenuate high frequency noise and improve the structural response of the enclosure.
  • the box can be constructed from a variety of materials such as thin steel, aluminum, etc.
  • the box is manufactured from 6.35 mm plexiglass and has dimensions 304.8 x 304.8 x 406.4 mm.
  • Piezoceramic control actuators such as 13, 14, 15 (type G1195 of thickness 0.19 mm and dimensions 38.1 x 63.5 mm) are bonded to the center of each panel.
  • Each actuator consists of a piezoceramic element bonded onto each side, co-located and wired in parallel with 180° phase shift. Such a configuration produces high vibration of the panels.
  • These elements can be positioned in various arrays and also embedded in the material if required.
  • a number of error microphones such as 16, 17, 18 are positioned in the radiated noise field.
  • the number and location of the error microphones is dependent upon the modal contribution (from the panel vibration) and radiation directivity of the noise.
  • a controller 19 is employed which measures the output of the error microphones and then constructs an oscillating control signal of the correct frequency content and phase which, when fed to the control actuators 13, 14, 15, etc. causes the sound to be markedly reduced at the error microphones and other locations.
  • An alternative to microphones is PVDF thin film which can be placed on the walls in such a way that energy in the radiating modes is sensed.
  • One possible configuration for the PVDF strips such as 20, 21, 22 is shown in Figure 1.
  • Another alternative would be to use accelerometers to sense the motion of specific points on the enclosure walls.
  • One particular control arrangement embodies the Filtered-X adaptive LMS algorithm discussed by Fuller.
  • An oscillating reference signal which has the frequency content of the noise to be canceled is taken from machine 50.
  • This reference signal 51 is also highly coherent with the output of the error microphones.
  • the reference signal is passed through an analog to digital (A/D) converter 52 and fed through a number of adaptive filter 53.
  • the number of adaptive filters is equal to the number of control actuators used.
  • the arrangement of the adaptive filter is dependent upon the frequency content of the noise.
  • the outputs of the adaptive filters is then passed through D/A converters 54 and smoothing filters 55.
  • this control signal is typically passed through a high voltage power amplifier and then connected to the electrodes of each actuator.
  • the error signals from the microphones 56 are sampled using A/D converters and then used in conjunction with the reference signal and a filtered-X update equation in the controller 61 in order to adapt or change the coefficients of the adaptive filters so as to minimize the error signals from the microphones as far as possible.
  • Figure 5 shows a typical radiation directivity pattern measured around the box at mid plane and a distance of 1.7m.
  • the curve 90 labeled “control off” gives the radiated noise field without any enclosure.
  • the curve 91 "control on” gives the radiated noise field when the box is in place but the control is not activated. It is apparent that the box only provides a small attenuation of the sound.
  • the results of Figure 6, labeled "with control” show high sound reductions of the order of 20 dB at all angles (i.e. global control).
  • the active attenuation is achieved as follows.
  • the noise source inside the box radiates sound which strikes the enclosure walls and causes it to vibrate (at the same frequency content as the noise source).
  • the vibrating walls then radiate sound away to the exterior free field of the box where it appears as unwanted noise.
  • the active inputs work as follows.
  • the structural actuators cause anti-vibration in the walls of the enclosure. When the inputs to the structural actuators are adjusted correctly these anti-vibrations cancel out those vibrations in the box which were previously radiating sound, thus leading to global sound reduction.
  • An alternative, shown in Figure 4, is to enclose the noisy structure 80 with close fitting panels 85 instead of a free standing enclosure.
  • the enclosure panels are attached directly to the sides of the noise source. If the regions generating noise are localized or if noise control is needed in certain directions, an advantage to this method is that the need to enclose the entire structure is eliminated. In addition, in many cases a more compact enclosure can be constructed without restricting airflow needed for cooling.
  • An example of an application of this method would be for the reduction of "hum" from electrical transformers. Transformer noise is generated from magnetostrictive forces in the coil and are propagated to the transformer skin through the oil field and coil foundation.
  • Figure 4 shows a cancellation system 80 for enclosing a noisy structure with close fitting panels.
  • Controller 81 receives a reference signal 82 from the structure and inputs 83, from error microphone 84.
  • Actuators 86 are located on close fitting panels 85.
  • Still another alternative shown in Figure 3 is to place the actuator directly on the surface of the noise source.
  • Figure 3 shows noise reduction system 70 with active structural control provided with a Noise Cancellation Technologies, Inc. controller 71 and power amplifier 72 having outputs to piezoceramic actuators such as 73, 74 and inputs from PVDF sensor film strips such as 75, 76, 77.
  • controller 71 and power amplifier 72 having outputs to piezoceramic actuators such as 73, 74 and inputs from PVDF sensor film strips such as 75, 76, 77.
  • An alternative to using structural actuators to anti-vibrate the enclosure walls is to use loudspeakers to generate a pressure field inside the box that will produce the anti-vibrations. Combinations of different sensors such as and microphones can also be used.

Landscapes

  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Claims (12)

  1. Système actif de réduction de bruit pour annuler une perturbation bruyante émanant d'une source de bruit, ledit système comportant
    des moyens formant enceinte structurelle (12) entourant au moins partiellement la source de bruit et ayant une pluralité de moyens actionneurs (13, 14, 15) fixés à ceux-ci pour amener les moyens formant enceinte à vibrer et produire des anti-vibrations, et
    une pluralité de moyens de détection d'erreurs (16,17,18) adaptés pour détecter un rayonnement de bruit et délivrer des signaux d'erreurs, et des moyens contrôleurs (19) comportant des moyens de circuit connectés aux moyens de détection d'erreurs et destinés à amener les moyens actionneurs à produire lesdites anti-vibrations,
       caractérisé en ce qu'un générateur de signal de référence est prévu pour alimenter les moyens contrôleurs en informations temporelles et de fréquence concernant la perturbation bruyante, en ce que les détecteurs d'erreurs sont adaptés pour détecter un bruit irradié dans le champ lointain à l'extérieur des moyens formant enceinte, et en ce que les moyens contrôleurs commandent de manière indépendante chacun des moyens actionneurs en fonction à la fois des signaux d'erreurs et du signal de référence (51) délivrés dans lesdits moyens contrôleurs afin d'amener simultanément les signaux d'erreurs à des valeurs minimales.
  2. Système selon la revendication 1, dans lequel lesdits moyens formant enceinte structurelle (12) ont une entrée d'air (23) à l'intérieur.
  3. Système selon la revendication 1, dans lequel lesdits moyens formant enceinte structurelle ont des moyens formant parois adaptés pour être ajustés de manière précise à ladite perturbation bruyante.
  4. Système selon la revendication 1, 2 ou 3, dans lequel lesdits moyens actionneurs sont des moyens actionneurs piézo-céramiques (13, 14, 15).
  5. Système selon la revendication 4, dans lequel lesdits moyens actionneurs sont des actionneurs piézo-céramiques encastrés.
  6. Système selon la revendication 4, dans lequel lesdits moyens actionneurs sont des actionneurs piézo-céramiques montés en surface.
  7. Système selon la revendication 1, 2 ou 3, dans lequel lesdits moyens actionneurs sont des vibreurs électrodynamiques.
  8. Système selon la revendication 1, 2 ou 3, dans lequel lesdits moyens actionneurs sont des moyens de haut-parleur.
  9. Système selon l'une quelconque des revendications 1 à 8, dans lequel les moyens de détection d'erreurs sont constitués d'un film de PVDF (20, 21, 22).
  10. Système selon l'une quelconque des revendications 1 à 8, dans lequel lesdits moyens de détection d'erreurs sont des microphones (16, 17, 18).
  11. Système selon l'une quelconque des revendications 1 à 8, dans lequel lesdits moyens de détection d'erreurs sont des hydrophones.
  12. Procédé de commande d'un rayonnement de bruit provenant d'une source de bruit en enfermant au moins partiellement la source dans une enceinte de réduction de bruit, dans laquelle une pluralité de moyens de détection d'erreurs détectent un rayonnement de bruit et délivrent des signaux d'erreurs dans des moyens contrôleurs qui, conformément auxdits signaux d'erreurs, délivrent des signaux d'entraínement dans une pluralité de moyens actionneurs pour faire vibrer l'enceinte de réduction de bruit afin de produire des anti-vibrations, caractérisé par les étapes consistant à (1) détecter le rayonnement en champ lointain à l'extérieur de l'enceinte par l'intermédiaire de la pluralité de moyens de détection d'erreurs, (2) produire un signal de référence comportant le contenu temporel et de fréquence de la source de bruit, (3) envoyer à la fois les signaux d'erreurs et le signal de référence dans les moyens contrôleurs, et (4) commander le rayonnement sonore au niveau de la pluralité des moyens de détection d'erreurs en ajustant des entrées oscillantes délivrées par les moyens contrôleurs dans la pluralité de moyens actionneurs conformément à un principe de commande pour amener simultanément les signaux d'erreurs à des valeurs minimales.
EP93904473A 1992-10-08 1992-10-08 Caisson actif reduisant la transmission acoustique Expired - Lifetime EP0664044B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PCT/US1992/008401 WO1994009484A1 (fr) 1992-10-08 1992-10-08 Caisson actif reduisant la transmission acoustique
CA002145862A CA2145862C (fr) 1992-10-08 1992-10-08 Boite d'attenuation acoustique active

Publications (3)

Publication Number Publication Date
EP0664044A1 EP0664044A1 (fr) 1995-07-26
EP0664044A4 EP0664044A4 (fr) 1996-04-03
EP0664044B1 true EP0664044B1 (fr) 1999-09-15

Family

ID=4155531

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93904473A Expired - Lifetime EP0664044B1 (fr) 1992-10-08 1992-10-08 Caisson actif reduisant la transmission acoustique

Country Status (1)

Country Link
EP (1) EP0664044B1 (fr)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4815139A (en) * 1988-03-16 1989-03-21 Nelson Industries, Inc. Active acoustic attenuation system for higher order mode non-uniform sound field in a duct

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0041954A1 (fr) * 1979-11-10 1981-12-23 Sound Attenuators Limited Suppression des vibrations transmises par un fluide dans un conteneur
JPS5895806A (ja) * 1981-12-02 1983-06-07 Hitachi Ltd 静止誘導電器の防音装置

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4815139A (en) * 1988-03-16 1989-03-21 Nelson Industries, Inc. Active acoustic attenuation system for higher order mode non-uniform sound field in a duct

Also Published As

Publication number Publication date
EP0664044A4 (fr) 1996-04-03
EP0664044A1 (fr) 1995-07-26

Similar Documents

Publication Publication Date Title
US5692053A (en) Active acoustic transmission loss box
US5315661A (en) Active high transmission loss panel
US5410607A (en) Method and apparatus for reducing noise radiated from a complex vibrating surface
US7706547B2 (en) System and method for noise cancellation
US5617479A (en) Global quieting system for stationary induction apparatus
JP3027824B2 (ja) 騒音及び振動防止用能動発泡プラスチック
US20090301805A1 (en) Active noise control system
WO1996011466A1 (fr) Dispositif de dissipation d'energie acoustique par contre-reaction avec compensateur
JPH05181488A (ja) 遮音構造体
US5414775A (en) Noise attenuation system for vibratory feeder bowl
US5790673A (en) Active acoustical controlled enclosure
Sampath et al. Active control of multiple tones in an enclosure
EP0664044B1 (fr) Caisson actif reduisant la transmission acoustique
WO1994009484A1 (fr) Caisson actif reduisant la transmission acoustique
Zhu et al. Active control of glass panels for reduction of sound transmission through windows
Curtis et al. An experimental investigation of three control strategies
Paurobally et al. Feedback control of noise transmission through a double-panel partition
JP2005062786A (ja) 騒音制御装置
WO1994029845A1 (fr) Haut-parleur monte en hauteur pour la suppression active du bruit
DE69230007T2 (de) Gehäuse mit aktiv erzeugtem akustischem Übertragungsverlust
Hansen Sensors and actuators for active noise control systems
Sampath et al. Active structural acoustic control of band-limited disturbances
JP2000294431A (ja) 防音装置
JPH10149172A (ja) 能動消音装置を備えた自家発電装置及び変圧器
Hansen et al. Use of perforated panels as an active control source

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19950407

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): BE DE DK FR GB IT NL SE

A4 Supplementary search report drawn up and despatched
AK Designated contracting states

Kind code of ref document: A4

Designated state(s): BE DE DK FR GB IT NL SE

17Q First examination report despatched

Effective date: 19980806

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: NCT GROUP, INC.

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): BE DE DK FR GB IT NL SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19990915

Ref country code: BE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19990915

REF Corresponds to:

Ref document number: 69230007

Country of ref document: DE

Date of ref document: 19991021

ITF It: translation for a ep patent filed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19991215

ET Fr: translation filed
NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20060915

Year of fee payment: 15

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20061005

Year of fee payment: 15

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20061031

Year of fee payment: 15

Ref country code: DE

Payment date: 20061031

Year of fee payment: 15

EUG Se: european patent has lapsed
GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20071008

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080501

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20080630

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20071009

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20061003

Year of fee payment: 15

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20071008

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20071031

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20071008