WO2002016797A1 - Suppression de bruit au moyen d'un oscillateur mecanique - Google Patents

Suppression de bruit au moyen d'un oscillateur mecanique Download PDF

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Publication number
WO2002016797A1
WO2002016797A1 PCT/US2001/026632 US0126632W WO0216797A1 WO 2002016797 A1 WO2002016797 A1 WO 2002016797A1 US 0126632 W US0126632 W US 0126632W WO 0216797 A1 WO0216797 A1 WO 0216797A1
Authority
WO
WIPO (PCT)
Prior art keywords
radiation
vibrating structure
cancelling device
radiating area
sound radiating
Prior art date
Application number
PCT/US2001/026632
Other languages
English (en)
Inventor
Jeffrey A. Zapfe
Original Assignee
Acentech, 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 Acentech, Inc. filed Critical Acentech, Inc.
Priority to AU2001288421A priority Critical patent/AU2001288421A1/en
Publication of WO2002016797A1 publication Critical patent/WO2002016797A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F7/00—Vibration-dampers; Shock-absorbers
    • F16F7/10—Vibration-dampers; Shock-absorbers using inertia effect
    • F16F7/104—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted
    • 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
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound

Definitions

  • BACKGROUND OF THE INVENTION Machines or equipment when in operation, often vibrate sufficiently to generate a significant amount of noise.
  • This noise can be of a sufficient volume or of a tone quality to interfer with surrounding activities .
  • Noise reduction attempts may also involve reconfiguring the vibrating surfaces so as to make them less efficient sound radiators (for example, by modifying their ribs and edge-connections . ) All of the foregoing typically involve changes in the basic design, which generally are costly and often may interfere with the basic function of the item under consideration. In many situations, these types of approaches cannot be implemented readily. In that case, one typically needs to consider "lagging" the radiating surfaces - that is, covering each such surface with a resilient layer (perhaps of soft fiberglass mat) , on top of which is placed a massive layer (a steel plate, lead sheet, or sheet of leaded vinyl, for example) . Lagging is one type of barrier system through which sound is transmitted relatively poorly. Other barrier arrangements consist of (partial or full) enclosures and of sound barrier walls (which, in fact, are partial enclosures) . These types of approaches, however, tend to interfere with cooling and ventilation, may require considerable space, and often are unsightly.
  • active noise cancellation systems have been developed. These, in essence, use one or more microphones to sense the radiated sound, one or more added sound sources, e.g., a loudspeaker, and control systems that cause the sound sources to produce sound that cancels the unwanted noise. Active systems typically are complex, expensive and relatively unreliable. Thus, new methods of reducing noise from a vibrating structure would clearly be desirable.
  • a mechanical oscillator that in concept consists of a spring-supported mass has a natural frequency that is directly proportional to the square root of the stiffness of the spring and inversely proportional to the square root of the mass. If such an oscillator is now affixed to a structure that vibrates at a frequency that is higher than the natural frequency of the oscillator, then the motion of the oscillator mass driven by that structure is opposite to the direction of motion of the structure (i.e., opposite in phase). Furthermore, at frequencies near the natural frequency of the oscillator, the excursions of the mass of the oscillator will be larger than those of the structure. Such an oscillator, if it is an efficient radiator of sound, can cancel sound produced by the vibrating structure.
  • the invention is directed to the application of the above principles to the reduction of noise radiated by a structure at a given frequency.
  • a radiation-cancelling device that acts like a resiliently supported mass with a significant sound radiating area is attached to the exterior surface of the structure to be quieted. Radiation from such a device, when properly constructed as describe herein, i.e., if the natural frequency and sound radiation characteristics of the mass are selected appropriately, cancels the sound radiating from the (preferably) considerably larger vibrating surfaces to which it is attached. If appropriate, more than one radiation- cancelling device may be attached to a given vibrating structure in a system according to the invention.
  • the radiation-cancelling device need not consist of separate spring and mass elements. It may consist, for example, of a circular plate that is rigidly connected at its midpoint to the vibrating structure. In this configuration, the plate serves as both the spring and the mass. In another configuration, the oscillator can be configured to resemble an inverted metal cup where the sides of the cup substantially serve the function of a spring. Radiation-cancelling devices according to the invention are useful for reducing the sound radiation from equipment items, such as transformers, which vibrate and radiate noise at a fixed frequency.
  • Fig. 1 is a schematic rendering of a system according to the invention
  • Fig. 2 is a graph showing relative movement of a vibrating structure and an attached radiation-cancelling device at various ratios of the driving frequency of the vibrating structure to the natural frequency of the radiation-cancelling device;
  • Fig. 3 is a schematic representation of two methods of reducing noise radiating from the underside of the radiation- cancelling device
  • Fig. 4 is a photograph of an experimental system according to the invention.
  • Fig. 5 is a diagrammatic representation of the system of Fig. 4;
  • Fig. 6 is a graph showing the predicted on-axis performance of the system of Fig. 4.
  • Fig. 7 is a graph showing the measured on-axis performance of the system of Fig. 4.
  • a system according to the invention provides a passive means for cancellation of undesirable radiated noise tones from a vibrating structure such as a transformer.
  • a vibrating structure can be represented as a base 10 having area A 0 and velocity amplitude V 0 .
  • An oscillating radiation-cancelling device 12 according to the invention, to be used to reduce noise from the vibrating structure, includes, in basic concept, a body
  • Body 14 of mass m, which is attached to the structure base 10 by a spring 16, having spring constant k.
  • Body 14 is represented as having area A x and velocity amplitude Vi.
  • Fig. 2 consider the behavior of the system as base 10 oscillates at different frequencies co compared to the natural frequency ⁇ n of radiation-cancelling device 12. It can be seen that at low frequencies of the driving structure,
  • the total radiated sound pressure p at a point some distance away from the structure and attached body is the combined pressure from the base and the body, and pressure p is proportional to V 0 A 0 + V]A ⁇ .
  • Vi is opposite in phase to V 0
  • the volume velocity (product of velocity amplitude and area) radiated from device body 14 cancels part of the volume velocity radiated from the base structure, and p will be reduced as V x A ⁇ is made larger. Therefore, if there is significant amplification of radiation-cancelling device 12, i.e, if V ⁇ »V 0 , only a small body mass area (Ai) is required to produce a total radiated pressure p near to zero.
  • Fig. 3 shows two options for minimizing this radiation: providing a baffle 18 or providing a flexible closure or bellows 20.
  • a baffle With a baffle, however, there are problems with alignment and with friction, which can induce damping and reduce the effectiveness of the system.
  • a bellows can induce noise radiation and create problems with keeping a constant system stiffness with changing temperature or external pressure.
  • FIG. 5 A schematic diagram of the system of Fig. 4 is given in Fig. 5.
  • the system according to the invention consists of a rigid piston 22 driven by shaker 24 to represent a vibrating structure to be quieted (equivalent to base 10 in Fig. 1) .
  • a radiating-cancelling device 26 bonded to piston 22 is in the form of an inverted metal cup.
  • the piston system is sealed in a heavy wooden box 28, and silicone is used to fill the gap 30 between the piston and the wooden box.
  • Metal cup 26 functions as a spring-mass system.
  • the metal of the cup provides a finite but minimal amount of material damping, and the stiff sides of the cup ensure that there is minimal unwanted radiation from the underside of the cup bottom to interfere with the sound radiation from the outside face of the cup.
  • the cup is also sealed to the piston to prevent additional damping due to air leakage from the underside of the cup.
  • the piston has a diameter of 12 cm, and the radiation-cancelling device (or damper) is a copper cup 4 cm in diameter (for an area ratio of approximately 12%) and approximately 1 mm thick.
  • An accelerometer is used to monitor the normal velocity of the piston and the sound pressure is measured with a microphone about 290 cm away. All tests were carried out in an anechoic chamber.
  • Fig. 6 a graph of the predicted sound pressure level versus the driving frequency.
  • the sound pressure will be amplified as the cup is vibrating with a much larger amplitude than that of the undamped piston.
  • the driving frequency increases, however, there is a phase shift and noise cancellation begins.
  • the total radiated sound pressure will be near zero.
  • Fig. 7 shows the measured on axis performance of the system. As can be seen, with the use of a system according to the invention, at a driving frequency of about 1065 Hz, the on-axis radiated sound pressure from the vibrating piston was reduced by almost 22 decibels.
  • the system of the invention finds useful application to quiet, e.g., electric transformers, enclosure bodies of fixed- speed machines and train-wheel screech.
  • a transformer is a prime candidate for application of the principles of the method of the invention because it always produces the same frequencies and because essentially no approaches except barriers and active systems have found to be useful so far.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Mechanical Engineering (AREA)
  • Multimedia (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

L'invention concerne un système et un procédé permettant de réduire le bruit émis par une structure vibrante à une fréquence donnée. Un dispositif de suppression (12) d'émissions, qui agit comme une masse (14) supportée élastiquement et présentant une aire (10) d'émission sonore importante, est fixé à la surface extérieure de la structure à rendre silencieuse. Les émissions émanant d'un tel dispositif, construit de façon que le mouvement de la structure vibrante fournisse la fréquence d'entraînement pour l'oscillation du système masse (14) à ressort (16) dans le dispositif de suppression (12) d'émissions et que la fréquence naturelle dudit système masse (14) à ressort (16) dans ledit dispositif de suppression (12) soit inférieure à la fréquence de vibration de la structure vibrante, suppriment le bruit émis par la surface vibrante beaucoup plus grande à laquelle le dispositif est fixé.
PCT/US2001/026632 2000-08-25 2001-08-27 Suppression de bruit au moyen d'un oscillateur mecanique WO2002016797A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001288421A AU2001288421A1 (en) 2000-08-25 2001-08-27 Noise cancellation using a mechanical oscillator

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US22781400P 2000-08-25 2000-08-25
US60/227,814 2000-08-25

Publications (1)

Publication Number Publication Date
WO2002016797A1 true WO2002016797A1 (fr) 2002-02-28

Family

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Family Applications (1)

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PCT/US2001/026632 WO2002016797A1 (fr) 2000-08-25 2001-08-27 Suppression de bruit au moyen d'un oscillateur mecanique

Country Status (3)

Country Link
US (1) US20020046901A1 (fr)
AU (1) AU2001288421A1 (fr)
WO (1) WO2002016797A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008003879A1 (fr) * 2006-07-05 2008-01-10 Peugeot Citroën Automobiles SA Dispositif pour amortir le bruit et les vibrations dues aux injecteurs dans un moteur de vehicule

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US7395898B2 (en) * 2004-03-05 2008-07-08 Rsm Technologies Limited Sound attenuating structures
US7565950B2 (en) * 2005-01-26 2009-07-28 The Aerospace Corporation Sound suppression material and method
DE102005045844B3 (de) * 2005-09-26 2007-02-01 Airbus Deutschland Gmbh Schalldämmelement und Verfahren zur Herstellung eines Schalldämmelements
US7753166B2 (en) * 2005-12-08 2010-07-13 Windsor Machine & Stamping Ltd Resonant frequency adjustor and method of utilizing the same
US20080185183A1 (en) * 2007-02-07 2008-08-07 Chien-Chung Chen Resonance-coordinating device for audio and video
WO2008101452A1 (fr) * 2007-02-21 2008-08-28 Fachhochschule Dortmund Résonateur à large bande pour réduire les vibrations et le bruit de pièces excitées par vibrations, notamment de pièces techniques
FR2914589B1 (fr) * 2007-04-06 2009-09-04 Saint Gobain Vitrage a propriete d'amortissement vibro-acoustique ameliore, procede de fabrication d'un tel vitrage et procede de protection acoustique dans un habitacle de vehicule
DE102008017418B4 (de) 2008-04-03 2010-08-19 Gottfried Wilhelm Leibniz Universität Hannover Vorrichtung zur Reduzierung der Übertragung und Ausbreitung von Schall und/oder Wellenbewegungen in einer Flüssigkeit
US8172036B2 (en) * 2010-09-10 2012-05-08 The Boeing Company Apparatus and method for providing acoustic metamaterial
US8752667B2 (en) * 2011-10-06 2014-06-17 Hrl Laboratories, Llc High bandwidth antiresonant membrane
US8960365B2 (en) * 2011-11-30 2015-02-24 The Hong Kong University Of Science And Technology Acoustic and vibrational energy absorption metamaterials
CN103137118B (zh) 2011-11-30 2016-07-06 香港科技大学 声能吸收超材料
CN103047336B (zh) * 2012-12-25 2014-08-27 国家电网公司 基于复合式隔振装置的结构传声控制方法
US11056092B2 (en) 2017-12-13 2021-07-06 The Boeing Company Anti-resonant panel and methods of making the same
US11315538B2 (en) 2017-12-13 2022-04-26 The Boeing Company Anti-resonant panels
US20200068292A1 (en) 2018-08-21 2020-02-27 Gopro, Inc. Audio Enhancements In Devices Using Motors

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US4724923A (en) * 1986-06-24 1988-02-16 Fokker B.V. Vibration absorber with controllable resonance frequency
US6062550A (en) * 1994-12-22 2000-05-16 Nissan Motor Co., Ltd. Vibration insulating device
US6213681B1 (en) * 1997-07-23 2001-04-10 Wacker-Werke Gmbh & Co., Kg Soil compacting device with adjustable vibration properties
US20010022256A1 (en) * 2000-01-18 2001-09-20 Kazuhito Misaji Vibration damper

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JPS58143510A (ja) * 1982-02-20 1983-08-26 Hitachi Ltd 静止誘導電器
SE441317B (sv) * 1984-02-14 1985-09-23 Asea Ab Ljuddempande anordning

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US4724923A (en) * 1986-06-24 1988-02-16 Fokker B.V. Vibration absorber with controllable resonance frequency
US6062550A (en) * 1994-12-22 2000-05-16 Nissan Motor Co., Ltd. Vibration insulating device
US6213681B1 (en) * 1997-07-23 2001-04-10 Wacker-Werke Gmbh & Co., Kg Soil compacting device with adjustable vibration properties
US20010022256A1 (en) * 2000-01-18 2001-09-20 Kazuhito Misaji Vibration damper

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008003879A1 (fr) * 2006-07-05 2008-01-10 Peugeot Citroën Automobiles SA Dispositif pour amortir le bruit et les vibrations dues aux injecteurs dans un moteur de vehicule
FR2903457A1 (fr) * 2006-07-05 2008-01-11 Peugeot Citroen Automobiles Sa Dispositif pour ameliorer le bruit et les vibrations dues aux injecteurs dans un moteur de vehicule

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Publication number Publication date
US20020046901A1 (en) 2002-04-25
AU2001288421A1 (en) 2002-03-04

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