EP0728535A1 - Verfahren und Vorrichtung zur Verminderung der Resonanzfrequenz von Hohlräumen von Unterwasserwandlern - Google Patents

Verfahren und Vorrichtung zur Verminderung der Resonanzfrequenz von Hohlräumen von Unterwasserwandlern Download PDF

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Publication number
EP0728535A1
EP0728535A1 EP96400364A EP96400364A EP0728535A1 EP 0728535 A1 EP0728535 A1 EP 0728535A1 EP 96400364 A EP96400364 A EP 96400364A EP 96400364 A EP96400364 A EP 96400364A EP 0728535 A1 EP0728535 A1 EP 0728535A1
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EP
European Patent Office
Prior art keywords
housing
orifice
cavity
pavilions
transducer
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Granted
Application number
EP96400364A
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English (en)
French (fr)
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EP0728535B1 (de
Inventor
Yves Ripoll
Jacky Garcin
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Direction General pour lArmement DGA
Etat Francais
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Direction General pour lArmement DGA
Etat Francais
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0611—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile
    • B06B1/0618—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile of piezo- and non-piezoelectric elements, e.g. 'Tonpilz'

Definitions

  • the present invention relates to methods and devices for reducing the resonance frequency of the cavities of the submersible transducers.
  • the technical sector of the invention is that of producing an electroacoustic submersible transducer.
  • the main application of the invention is to reduce this resonant frequency for so-called double "Tonpilz" transducers and in particular for those used to emit acoustic waves with high efficiency and around a given master plan and omnidirectionally following this plan.
  • Such immersible electroacoustic transducers and in particular piezoelectric transducers, are known, comprising a rigid cylindrical housing, hollow and open at its two axial ends, and inside which are arranged coaxially with the latter, two identical electro-acoustic motors, placed on either side of a central counterweight, and the opposite ends of which are surrounded by a flag.
  • Such transducers are called double "Tonpilz”.
  • Said electro-acoustic motors can be produced by two stacks of aligned piezoelectric plates. The external faces of the two flags are located in the plane of the axial ends of the housing, so that they are in contact with the liquid, in which the housing is immersed, and the external perimeter of these flags comes as close as possible to the edge. open axial ends of said housing.
  • these external faces emit acoustic waves into the liquid when the electro-acoustic motors are electronically excited: these transducers are used in particular to emit low frequency acoustic waves in water in a determined direction; for an application of this type of mono or double "Tonpilz" transducer to high power emissions, mention may be made of the application FR. 2,663,181 by Gilles GROSSO published on December 13, 1991, which describes additional devices to obtain increased power.
  • the main problem posed is therefore to be able to decrease the resonant frequency of the resonator, that is to say of the resonant cavities of a transducer of the type, in particular, double "Tonpilz" without increasing its dimensions and weight from a conventional transducer of the same type, and with at least the same sound power for at most the same power consumed .
  • a dynamic load integral with the latter partially closing its internal section and sharing said cavity interior in two rear and front parts communicating and the peripheral external edge of the pavilions of the internal wall of the housing is brought closer preferably at a distance of a few tenths of a millimeter.
  • said transducer thus produced is used in a frequency range surrounding that specific to the rear cavity thus delimited by said dynamic load: the definition and a type of embodiment thereof is given in the description below.
  • the presence of said dynamic load makes it possible in fact to indirectly increase the mass of the roof by association of a mass of liquid situated between the latter and said dynamic load; as the latter only partially closes the interior section of the housing, the liquid can however pass from the so-called front cavity to the so-called rear cavity but being braked according to the surface area ratio between the free surface of the conduit left by said dynamic load and the total internal surface of the housing: a virtual mass of the roof is thus obtained, the greater the higher this surface ratio.
  • said extension is extended rigid housing defined above, which is cylindrical with axis XX 'and encloses the two electroacoustic motors each associated with a horn, beyond these and in the axis XX'; two cavities are thus formed, each comprising an axial end orifice in front of the pavilions and the resonance of which is determined to correspond to the desired range of emission frequency; we are closing then completely the part of the housing located between the two said pavilions and enclosing a central cavity and the two end orifices of said housing are closed, each by a passive radiator.
  • one of the main applications of this latter embodiment is the possibility of emitting and / or receiving high-efficiency acoustic waves in horizontal planes to study the different properties, by layers or by slices, of the oceans, such as temperature, salinity, density, currents etc ..., both for understanding the phenomena and their fluctuation over time.
  • a technique known as “acoustic ocean tomography” has been developed for this to generate a three-dimensional image of the area crossed by sound waves, as is done in medicine with "X” beams, or in geology of the earth's crust with seismic waves: in the oceanic domain, low frequency acoustic waves are used.
  • these can enclose either closed, leaktight elastic tubes filled with gas, or at least one flexible bladder occupying part of its volume and filled with a more compressible fluid than the immersion liquid: the advantage of the presence of such so-called compliant tubes and / or of a bladder is also to reduce the loss of efficiency and attenuation of frequencies between the two resonance peaks specific to the transducer, one of which is linked to the mechanical resonance of the transducer assembly, and the other to that of its cavity.
  • Figure 1 is an axial sectional view of a transducer of the type indicated above with a central cavity open to the outside and defined below and equipped with a passive radiator according to the invention.
  • Figure 2 is a perspective view of a passive radiator according to Figure 1.
  • FIG. 3 represents comparative curves of sound power, between a conventional known transducer with double “Tonpilz” and a transducer of the same type equipped with a passive radiator, with respect to the frequency emitted.
  • Figure 4 is an axial sectional view of a half-transducer of the type indicated above, with three cavities, two of which are said to be front, each equipped with a passive radiator according to the invention.
  • the transducer as shown in section in this FIG. 1 therefore comprises, in a known manner, two electro-acoustic motors 1 aligned on an axis XX ', placed on either side of a central counterweight 2 and coaxially with the interior of a cylindrical housing 5, which can be called external covering all of said motors 1 up to the pavilions 3 at the end thereof, the cavity 7, thus delimited by said pavilions and said housing being filled with liquid 4 in which the entire transducer is immersed, such as sea water.
  • Said electro-acoustic motors 1 and the intermediate mass 2 are on the one hand, held together by a prestressing rod 9, also immobilizing by any means of assembly the two pavilions 3 on the ends of the pillar thus formed, and on the other part, assembled by means of different connecting pieces 11, themselves associated with different fixing pieces 12 to the external housing 5.
  • the various fixing means are such that they allow freedom of movement of the ends of the electro-acoustic motors on the side pavilions 3, which are integral with them and whose peripheral external edge 16, not connected and independent of the internal wall of the housing 5, can then vibrate freely so as to ensure the full emission of acoustic waves in the ambient environment.
  • An inner sleeve 13 isolates the preload rod from said motors 1, and an outer sealing envelope 8 ensures the insulation of these motors 1 and of the pavilions 3 with respect to the ambient medium 4.
  • the power of said electro-acoustic motors 1 is supplied by any power cable 10 fixed on said connecting parts 11 by an electrical connector 14.
  • the production of such a transducer and all of the various connecting parts constituting it are in the known field and can be carried out by any person skilled in the art: all the other elements making it possible in particular to obtain the Helmholtz resonance of the cavity as indicated in the introduction, as well as the various connecting elements making it possible to improve the mechanical production of the assembly are not shown here; some have been the subject of various other patent applications, such as those cited in particular in the introduction for so-called compliant tubes as shown in FIG. 4.
  • said external housing 5 comprises at least one opening 6 for communication with the outside, said opening possibly consisting of holes distributed around the cylindrical part of the housing or even consisting of a complete circular peripheral opening.
  • said opening or orifice 6, or also called vent is closed by a passive radiator 15 consisting of one or more solid plates of thickness "L", made of a material denser than said fluid 4, and suspended on the periphery of said orifice or vent by an elastic material 23 this or these plates constituting said passive radiator 15 preferably match the shape of the opening 6, 20 which they seal and that of the case 5 of which they then ensure continuity of surface.
  • the material of the plates of said passive radiator 15 may be metallic, of aluminum bronze or steel type, etc.: if the acoustic mass of the vent neck 20 thus closed is thus increased in a ratio of the order of eight, decreases the resonance frequency of the cavity as shown in Figure 3 and according to the equivalent acoustic mass thus obtained, one can also widen the range of this resonance frequency.
  • this acoustic mass is determined by the product of the density of the material multiplied by the height of the neck of the vent, that is to say in the present invention the thickness "L" of the plates constituting the passive radiator 15, and divided by the total area of the vent opening 20, if we increase the density of the material without changing the dimensions of the vent, we obtain actually a higher acoustic mass; conversely for the same acoustic mass, if the density is increased, the radiation area of this vent is increased and thus the impedance of the acoustic radiation.
  • said passive radiator 15 is made up of several independent plates or sectors 16 and connected together by elastic connections 17, as shown in perspective in FIG. 2, in which the total surface of the cylindrical vent or opening 6 is thus closed by eight sectors 16.
  • said transducer as shown in dotted lines on the left in FIG. 1 can comprise behind each pavilion 3 and inside the case 5 a dynamic load 22 associated with each of the pavilions, integral with said case 5 and partially closing its inner section by dividing the internal cavity 7 into two parts, rear 71 and front 72, communicating: in the representation of Figure 1, this in fact corresponds to dividing the entire internal cavity of the housing into three cavities, of which only one rear central 71 is median and two so-called "front" cavities 72 are each located behind each of the two pavilions 3.
  • this consists of a solid wall 27 conforming to the shape of the internal surface of the wall of the housing 5 of which it is integral, surrounding the engine pillar 1 and drilled in less than one orifice 26 through which the latter passes, which orifice carries a conduit 28 extending behind the wall 27 relative to the pavilion 3 and leaving a free peripheral passage around said driving pillar 1.
  • FIG 3 there is shown a curve 24 of acoustic power emission of a known transducer as shown in Figure 1 with a passive radiator according to the invention, while curve 25 represents the same transducer but not equipped of said passive radiator, said emission powers being noted with respect to the frequencies in herz: it is thus noted that the resonant frequency of approximately 580 Hz is reduced by more than 100 Hz for the same emission power. This was of course measured from a given type of transducer, but with other transducers, we would obtain equivalent results with always the same shift in reduction of the resonance and emission frequency.
  • the submersible electroacoustic transducer as shown in section in FIG. 4 comprises, in a manner known as that of FIG. 1, two electroacoustic motors 1, aligned along an axis XX ′, placed on either side 'other of a central countermass 2 and coaxially inside a rigid cylindrical casing 5 of the same axis XX', covering all of said motors 1 up to the pavilions 3 at the end thereof and open itself- even at its two ends; the cavity 7 thus delimited between and at the rear of said pavilions and by the housing itself is in communication with the external immersion liquid 10, by the only annular spaces "e” between the internal shape of said rigid housing 5 and the peripheral edges of the ends of the pavilions 3: this space "e” should be as small as possible, ie less than 0.5 mm to avoid pumping of the liquid between the front and the rear of said pavilions, as in the example of Figure 1 with dynamic load 27, although in this example this distance is less critical. No other communication or vent is made in the housing
  • said rigid housing 5 extends along its axis XX ′ beyond the two pavilions 3 and constitutes therewith two cavities 19 whose resonance corresponds to the desired emission frequency.
  • said cavities 16 may contain elastic tubes 18 closed, sealed and filled with gas, which are called compliant tubes, such as those described in the patent application FR. 2,665,998 of May 5, 1988.
  • the opening 20 of said cavities 19 on the outside are of a diameter d smaller than the internal diameter D of the rigid housing 5 a dimensional compromise must then be found between the total dimension of the cavity, the compliant tubes or other devices as described below, and the diameter of this opening.
  • said cavity 7 inside said housing 5 and located between the two pavilions 3 and in which said electroacoustic motors 1 are located can indeed also enclose elastic tubes 18, closed, sealed and filled with gas, called therefore compliant.
  • each orifice 20, or axial end opening or vent, of said front cavities 19 is closed by a passive radiator 15 constituted by a plate of a material of higher density than the medium 4: as indicated previously, it can be a metallic piece of steel or aluminum bronze; this plate is suspended at the periphery of the opening or vent by an elastic suspension 23, and can be of convex shape.
  • said compliant tubes 18 can be replaced in any one of the cavities 7, 19 by at least one flexible bladder occupying at least part if not all of the entire volume of the cavity concerned and filled with a more compressible fluid than the ambient liquid 4: this can be applied either for the cavity 7, or for the end cavities 19, or for all of said cavities.
  • the fluid occupying the volumes delimited by the skin of said bladders must fill at best and preferably practically the entire cavity, because its volume must in fact be greater than that of the compliant tubes 18 represented and as described above, so as to have compressibility characteristics equivalent to that of said tubes as used to date in other types of transducers.
  • the compressibility of said fluid must in fact be less than 10 9 N / m 2 , defined by the product of its density P f with the square of the speed of propagation of sound in this fluid C f .
  • a fluid from the family of fully fluorinated organic compounds of the C8H18 type is thus preferably chosen; in addition, the viscosity should not be too high, or lower than that of water, preferably less than 6.5 x 10 -7 m 2 per second which is the viscosity of silicone oil.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)
EP96400364A 1995-02-23 1996-02-22 Verfahren und Vorrichtung zur Verminderung der Resonanzfrequenz von Hohlräumen von Unterwasserwandlern Expired - Lifetime EP0728535B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9502093A FR2731129B1 (fr) 1995-02-23 1995-02-23 Procede et dispositif pour diminuer la frequence de resonance des cavites des transducteurs immergeables
FR9502093 1995-02-23

Publications (2)

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EP0728535A1 true EP0728535A1 (de) 1996-08-28
EP0728535B1 EP0728535B1 (de) 1998-08-26

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EP96400364A Expired - Lifetime EP0728535B1 (de) 1995-02-23 1996-02-22 Verfahren und Vorrichtung zur Verminderung der Resonanzfrequenz von Hohlräumen von Unterwasserwandlern

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US (1) US5694374A (de)
EP (1) EP0728535B1 (de)
CA (1) CA2170090A1 (de)
DE (1) DE69600549T2 (de)
FR (1) FR2731129B1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2940579A1 (fr) * 2008-12-23 2010-06-25 Ixsea Transducteur d'ondes acoustiques et antenne sonar de directivite amelioree.

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6310427B1 (en) * 2000-05-03 2001-10-30 Bae Systems Aerospace Inc. Connecting apparatus for electro-acoustic devices
FR2818754B1 (fr) * 2000-12-21 2004-06-18 Inst Francais Du Petrole Dispositif pour engendrer des ondes elastiques focalisees dans un milieu materiel tel que le sous-sol, et methode pour sa mise en oeuvre
WO2006052970A2 (en) * 2004-11-08 2006-05-18 Lockheed Martin Corporation Flexural cylinder projector
US8240426B2 (en) 2010-08-19 2012-08-14 Bose Corporation Three dimensional acoustic passive radiating
FR2971112B1 (fr) * 2011-02-01 2014-01-03 Ixblue Transducteur electro-acoustique basse frequence et procede de generation d'ondes acoustiques.
US9995834B2 (en) * 2013-05-07 2018-06-12 Pgs Geophysical As Variable mass load marine vibrator
US10488542B2 (en) * 2014-12-02 2019-11-26 Pgs Geophysical As Use of external driver to energize a seismic source
DE102015212686A1 (de) * 2015-07-07 2017-01-12 Robert Bosch Gmbh Schallwandler
US20180164460A1 (en) * 2016-12-13 2018-06-14 Pgs Geophysical As Dipole-Type Source for Generating Low Frequency Pressure Wave Fields

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0462037A1 (de) * 1990-06-12 1991-12-18 Gilles A . Grosso Elektroakustischer Unterwasserwandler
FR2665998A1 (fr) * 1988-05-05 1992-02-21 France Etat Armement Procedes et transducteurs electro-acoustiques pour emettre des ondes acoustiques a basse frequence dans un liquide.

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2713429B1 (fr) * 1993-12-03 1996-02-09 France Etat Armement Procédé d'émission de forte puissance d'ondes acoustiques et pavillons de transducteurs correspondants.

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2665998A1 (fr) * 1988-05-05 1992-02-21 France Etat Armement Procedes et transducteurs electro-acoustiques pour emettre des ondes acoustiques a basse frequence dans un liquide.
EP0462037A1 (de) * 1990-06-12 1991-12-18 Gilles A . Grosso Elektroakustischer Unterwasserwandler

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2940579A1 (fr) * 2008-12-23 2010-06-25 Ixsea Transducteur d'ondes acoustiques et antenne sonar de directivite amelioree.
WO2010072984A1 (fr) * 2008-12-23 2010-07-01 Ixsea Transducteur d'ondes acoustiques et antenne sonar de directivite amelioree
US8780674B2 (en) 2008-12-23 2014-07-15 Ixblue Acoustic wave transducer and sonar antenna with improved directivity

Also Published As

Publication number Publication date
FR2731129B1 (fr) 1997-04-11
FR2731129A1 (fr) 1996-08-30
DE69600549T2 (de) 1999-02-11
CA2170090A1 (fr) 1996-08-24
EP0728535B1 (de) 1998-08-26
US5694374A (en) 1997-12-02
DE69600549D1 (de) 1998-10-01

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