EP1157751B1 - Electrodynamic transducer for underwater acoustic - Google Patents

Electrodynamic transducer for underwater acoustic Download PDF

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Publication number
EP1157751B1
EP1157751B1 EP01401347A EP01401347A EP1157751B1 EP 1157751 B1 EP1157751 B1 EP 1157751B1 EP 01401347 A EP01401347 A EP 01401347A EP 01401347 A EP01401347 A EP 01401347A EP 1157751 B1 EP1157751 B1 EP 1157751B1
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EP
European Patent Office
Prior art keywords
transducer
air
pole pieces
dome
winding
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EP01401347A
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German (de)
French (fr)
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EP1157751A1 (en
Inventor
Vito Thomson-CSF Prop. Int. Dept. Brevets Suppa
M. Thomson-CSF Prop. Int. Dept. Brevets Letiche
M. Thomson-CSF Prop. Int. Dept. Brevets Lattard
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Thales Underwater Systems SAS
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Thales Underwater Systems SAS
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    • GPHYSICS
    • G10MUSICAL INSTRUMENTS; ACOUSTICS
    • G10KSOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00Methods 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
    • G10K11/004Mounting transducers, e.g. provided with mechanical moving or orienting device
    • G10K11/006Transducer mounting in underwater equipment, e.g. sonobuoys
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B06GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06BMETHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/04Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism
    • B06B1/045Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism using vibrating magnet, armature or coil system

Definitions

  • the present invention relates to transducers of the electrodynamic type which make it possible to emit acoustic waves in the sea, more particularly sound waves. These transducers are particularly useful in sonar technique.
  • Underwater acoustics are used for towed fish with electronic devices and various transducers that can operate in transmission, reception and possibly in both modes.
  • transducers of the electrodynamic type which comprise a flag driven by a voice coil located in an air gap.
  • This transducer according to the prior art, represented on the Figures 1 and 2 appended, comprises a body formed of a base 101 on which is fitted a shirt 102 surmounted by a cup 103. These different parts fit into each other so as to define cylindrical cavities of revolution around the l axis of the transducer, in which are inserted the other parts forming the transducer.
  • a first cylindrical cavity delimited between the base and the liner makes it possible to maintain a magnetic circuit formed of first and second pole pieces 104 and 105 in the form of rings centered on the axis of the transducer.
  • the first pole piece 104 is L-shaped with the inner branch of the L that overflows inside the central chamber of the transducer.
  • the second pole piece 105 is in the form of a flat washer. Both are kept separated by a set of magnets 106 on which they are tightened by the adjustment of the liner 102 in the base 101. In this way, a magnetic circuit is obtained which is only interrupted by a thin air gap 107 presenting the shape of a cylinder centered on the axis of the transducer and coming flush with the inner lateral surface of the cup 103.
  • the central space of the transducer body forms a second cylindrical cavity in which a mushroom-shaped core 108 is embedded by its central rod in the central circular opening of the pole piece 104.
  • the moving element of the transducer is formed by a hollow piece 109 having the shape of a dome covering a cylindrical portion which engages in the air gap 107. So that this piece is at the same time very solid, very light and very rigid, it is for example formed by a carbon fiber fabric embedded in a resin matrix.
  • the upper surface of the dome 109 is covered with a part 110 whose upper surface is substantially flat and which forms the radiative flag of the transducer. It is performed to be itself very light, for example syntactic foam.
  • Crown 110 therefore behaves like a piston whose lateral outer surface is cylindrical. This piston slides in a cylinder formed by the lateral inner surface of the cup 103, itself substantially cylindrical. These two parts, and more particularly the roof 110, are made to have an extremely small adjustment play, of the order of 0.2 mm for example. A mechanical filter is thus formed which slows down the propagation of the shock wave that may come from an eventual external explosion, by rolling in this gap the fluid in which the flag is bathed.
  • the upper part of the central space of the transducer body is filled with a fluid, an oil for example, adapted to both this protection and the propagation of acoustic waves.
  • a fluid an oil for example, adapted to both this protection and the propagation of acoustic waves.
  • the space 113 is closed at its upper part by a membrane 112, which is fixed on the periphery of the cup 103.
  • the lower part of the central space, opposite the part where the oil is, is filled with air.
  • another sealing membrane 115 made of rubber for example, which is much more flexible than the membrane 112 and which is a part fixed on the outer side wall of the roof 110 and secondly on the inner side wall of the cup 103. This attachment is made by pinching between the cup 103 and the shirt 102.
  • the external lateral surface of the flag is machined at this level to present a withdrawal relative to the nozzle 111, which has the reduced clearance described above, and form a free space for the membrane 115.
  • this assembly is stiffened by using a set of radial ribs 116 which are distributed on the inner periphery of the dome 109 and meet in a star below the lower part of the mushroom rod forming the core 108. These ribs slide in grooves 117 formed in the core 108 and in the first pole piece 104. These grooves are relatively wide at the core and are narrower at the pole piece to minimize the loss of magnetic flux, which can be reduced to a very low value. low of a few percent.
  • An axis 118 joins the center of the upper part of the dome 109 in the center of the star formed by the reunion of the ribs 116, below the lower face of the core 108.
  • This axis makes it possible at the same time to stiffen the assembly and to ensure its vertical centering with respect to the axis of the transducer.
  • the axis is fixed by its lower part in the center of a flat spring 119 itself fixed circumferentially in the lower part of the base 101.
  • This spring of the type known as "flector Is formed of a flexible and resilient washer carrying circumferential openings for allowing air to pass freely in the lower part of the central space of the transducer, between the two parts delimited by the plane of this spring. This spring ensures not only the centering, but it avoids the rotational movements of the moving element that would rub the ribs against the walls of the grooves in which they slide.
  • the driving action that makes it possible to move the dome / horn assembly along the axis of the transducer, to emit the acoustic waves, is obtained by the interaction between the magnetic field which circulates between the pole pieces and that delivered by a coil 120 wound on the lateral flanks of the lower cylindrical portion of the dome 109.
  • This coil is thus immersed in the air gap existing between the two pole pieces, which realizes the conventional diagram of an electrodynamic transducer, this coil is powered by means not shown in the figure and which are known in the art.
  • the ribs 116 also serve as a heat sink over the entire height of the coil 120, to dissipate the heat generated at this level by directing it to the other parts of the transducer.
  • the internal portion 114 delimited by the dome 109, the base 101 whose bottom is closed, the jacket 102 and the sealing membrane 115 is filled with air to allow the movement of the moving assembly, as has been seen above.
  • the mobile assembly When the transducer is immersed, under the effect of the hydrostatic pressure, the mobile assembly is sinking towards the bottom of the base 101 by compressing the spring 119 and the volume of air included in this portion 114.
  • This movement of course, to modify the electroacoustic characteristics of the transducer, in particular by modifying the respective positions of the coil and the pole pieces,
  • a compensation tank, or air chamber, 121 formed of a flexible bag, of rubber for example, subjected to the pressure of the marine environment and communicating with the part 114 by 122.
  • this inner tube is of toroidal shape and is located in another internal cylindrical cavity 123 which is delimited to the interior of the transducer by the walls of the jacket 102 and the cup 103. This cavity is itself toroidal and closed and surrounds the location of the flag 110.
  • openings 124 which allow the seawater to enter the cavity 123 and to compress the air chamber.
  • the inner tube is protected against mechanical external aggression by the walls of the cavity where it is located.
  • the diameter of the openings 124 is provided so that the shock waves from an eventual external explosion is attenuated through these openings, so that they do not present any danger of overpressure at the level of the inner tube.
  • These openings being round, their diameter may be greater than the thickness of the nozzle 111.
  • Such a transducer works perfectly, and resists for example the explosion of a ton of TNT located 30m from it.
  • the large current which then flows in the coil 120 causes a strong local heating which can not be dissipated properly by the means provided to date, in particular by the fins 116.
  • an electrodynamic transducer for underwater acoustics of the type comprising a body provided with pole pieces defining an air gap, a moving element provided with an extended dome by a cylinder supporting a sliding winding in this air gap, a flexible membrane ensuring the seal between the mobile equipment and the body by determining an inner part filled with air, and a flag overlying said dome and sliding in said body forming with it is a nozzle whose play value is set so as to protect said membrane against shock waves from explosions external to the transducer by laminating these shock waves in said nozzle, mainly characterized in that one said pole pieces is provided with at least one opening for the circulation of air inside the inner part for effectively cooling said winding.
  • it further comprises a conductive mass of the heat located between said pole pieces for draining the heat generated by the winding towards the outside of the transducer.
  • it further comprises a set of magnets placed between the pole pieces, characterized in that it further comprises a set of heat conductive masses interposed between the magnets.
  • said heat-conducting masses are made of aluminum.
  • the invention therefore proposes to eliminate the confinement of the air in this part 130 where the lower part of the coil 120 is immersed by forming holes 131 in the magnetic circuit 104.
  • These holes which are in this embodiment substantially vertical, therefore put in communication the portion 130 of the cavity 114 with the portion 126 of the same cavity, located at the bottom of the transducer under the core 108.
  • the communication additional created thus between the portion 125 of the cavity 114, located above the core 108 and this portion 126, allows a flow of air.
  • the latter having heated in contact with the coil 120 comes up in the part 125, cools by contact with the different massive parts of the transducer, then returns to the portion 126 of the cavity 114 down through the various orifices located in the central part of the transducer.
  • the invention proposes, in the exemplary embodiment shown on the Figures 3 and 4 , machining the lower portion of the housing 101, inside thereof at the portion 126 of the cavity 114, milling the interior thereof so as to disengage a circular shoulder 132 so that the holes 131 may themselves be machined vertically while opening into the portion 126 of the cavity 114.
  • the invention proposes, to improve the transfer of heat between the inside of the transducer, more particularly since the volume of air flowing at the portion 130 of the cavity 114, to place between the magnets 106 metal masses 135 which form thermal drains between the inside of the transducer and the external environment, by the intermediate of the shirt 102.
  • These metal masses are machined to provide a maximum thermal path to the heat released by occupying as much space as possible between the magnets. They are made of a material that is as much as possible heat conductor while remaining light enough not to weigh down the mass of the transducer. Among the most suitable materials for this use include aluminum. They are held, for example by gluing, on the pole piece 104, or possibly by pinching between the pole pieces 104 and 105 in the same manner as the magnets 106.
  • a transducer made in this way can withstand a current that can be at least 4 times higher than the admissible current in a transducer according to the prior art, without it being necessary to make any modification to the rest of the transducer, in particular to the coil, and obtaining identical performance without any degradation.

Description

La présente invention se rapporte aux transducteurs du type électrodynamique qui permettent d'émettre au sein de la mer des ondes acoustiques, plus particulièrement des ondes sonores. Ces transducteurs sont particulièrement utiles en technique sonar.The present invention relates to transducers of the electrodynamic type which make it possible to emit acoustic waves in the sea, more particularly sound waves. These transducers are particularly useful in sonar technique.

On utilise en acoustique sous-marine des poissons remorqués comportant des appareils électroniques et des transducteurs divers pouvant fonctionner en émission, en réception et éventuellement dans les deux modes.Underwater acoustics are used for towed fish with electronic devices and various transducers that can operate in transmission, reception and possibly in both modes.

On sait qu'en basse fréquence, typiquement entre 10 Hz et 1kHz, pour pouvoir émettre une puissance acoustique suffisante il faut déplacer des masses d'eau importantes, ce qui nécessite un déplacement lui-même important de la face active du transducteur. Ceci amène à utiliser dans ce cas généralement des transducteurs du type électrodynamique, qui comprennent un pavillon entraîné par une bobine mobile située dans un entrefer. Ces transducteurs de ce type sont tout à fait semblables aux haut-parleurs bien connus en acoustique musicale.It is known that in low frequency, typically between 10 Hz and 1 kHz, in order to be able to emit sufficient acoustic power, it is necessary to move large masses of water, which necessitates a significant displacement of the active face of the transducer. This leads to use in this case generally transducers of the electrodynamic type, which comprise a flag driven by a voice coil located in an air gap. These transducers of this type are quite similar to the well-known loudspeakers in musical acoustics.

Pour pouvoir obtenir la puissance acoustique fréquemment requise dans certaines applications, compte tenu du niveau sonore à atteindre, qui peut atteindre 150 dB à 10 Hz, on est amené à utiliser des transducteurs présentant des dimensions relativement importantes. Ceci entraîne des contraintes, tant en volume qu'en poids, parce que le transducteur doit être immergé dans la mer en étant placé dans un poisson qui doit naviguer à une immersion prédéterminée.In order to be able to obtain the acoustic power frequently required in certain applications, taking into account the noise level to be attained, which can reach 150 dB at 10 Hz, it is necessary to use transducers having relatively large dimensions. This entails constraints, both in volume and weight, because the transducer must be immersed in the sea by being placed in a fish that must navigate to a predetermined immersion.

La demanderesse a décrit et revendiqué dans un brevet français déposé le 27 mai 1997 sous le n° 97 06457 , publié le 04 décembre 1998 sous le n° 2 764 160 et délivré le 27 août 1999, un transducteur électrodynamique de ce type qui permet de délivrer une puissance acoustique importante en présentant un volume et une masse raisonnable, tout en étant particulièrement conçu pour résister aux explosions sous-marines qui se produisent parfois à proximité de tels transducteurs.Applicant has described and claimed in a patent French patent deposited on May 27, 1997 under the number 97 06457 , published on December 04, 1998 under number 2,764,160 and issued August 27, 1999, an electrodynamic transducer of this type that delivers a significant acoustic power having a volume and a reasonable mass, while being particularly designed to withstand submarine explosions that sometimes occur in the vicinity of such transducers.

Ce transducteur selon l'art antérieur, représenté sur les figures 1 et 2 annexées, comprend un corps formé d'une embase 101 sur laquelle vient s'emmancher une chemise 102 surmontée d'une coupelle 103. Ces différentes pièces s'emboîtent les unes dans les autres de manière à délimiter des cavités cylindriques de révolution autour de l'axe du transducteur, dans lesquelles viennent s'insérer les autres pièces formant ce transducteur.This transducer according to the prior art, represented on the Figures 1 and 2 appended, comprises a body formed of a base 101 on which is fitted a shirt 102 surmounted by a cup 103. These different parts fit into each other so as to define cylindrical cavities of revolution around the l axis of the transducer, in which are inserted the other parts forming the transducer.

Une première cavité cylindrique délimitée entre l'embase et la chemise permet de maintenir un circuit magnétique formé d'une première et d'une deuxième pièces polaires 104 et 105 en forme de couronnes centrées sur l'axe du transducteur. La première pièce polaire 104 est en forme de L avec la branche intérieure du L qui vient déborder à l'intérieur de la chambre centrale du transducteur. La deuxième pièce polaire 105 est en forme de rondelle plate. Toutes deux sont maintenues séparées par un jeu d'aimants 106 sur lesquels elles sont serrées par l'ajustement de la chemise 102 dans l'embase 101. On obtient de cette manière un circuit magnétique qui est seulement interrompu par un entrefer mince 107 présentant la forme d'un cylindre centré sur l'axe du transducteur et venant au ras de la surface latérale intérieure de la coupelle 103.A first cylindrical cavity delimited between the base and the liner makes it possible to maintain a magnetic circuit formed of first and second pole pieces 104 and 105 in the form of rings centered on the axis of the transducer. The first pole piece 104 is L-shaped with the inner branch of the L that overflows inside the central chamber of the transducer. The second pole piece 105 is in the form of a flat washer. Both are kept separated by a set of magnets 106 on which they are tightened by the adjustment of the liner 102 in the base 101. In this way, a magnetic circuit is obtained which is only interrupted by a thin air gap 107 presenting the shape of a cylinder centered on the axis of the transducer and coming flush with the inner lateral surface of the cup 103.

L'espace central du corps du transducteur forme une deuxième cavité cylindrique dans laquelle un noyau 108, en forme de champignon, vient s'encastrer par sa tige centrale dans l'ouverture circulaire centrale de la pièce polaire 104. La partie inférieure de la tête du noyau, de forme sensiblement hémisphérique, s'appuie sur la partie supérieure de cette même pièce polaire 104.The central space of the transducer body forms a second cylindrical cavity in which a mushroom-shaped core 108 is embedded by its central rod in the central circular opening of the pole piece 104. The lower part of the head the core, substantially hemispherical in shape, rests on the upper part of this same pole piece 104.

L'équipage mobile du transducteur est formé par une pièce creuse 109 ayant la forme d'un dôme coiffant une partie cylindrique qui vient s'engager dans l'entrefer 107. Pour que cette pièce soit à la fois très solide, très légère et très rigide, elle est par exemple formée par un tissu de fibres de carbone noyé dans une matrice en résine. La surface supérieure du dôme 109 est recouverte d'une pièce 110 dont la surface supérieure est sensiblement plate et qui forme le pavillon radiatif du transducteur. Elle est réalisée, pour être elle-même très légère, par exemple en mousse syntactique.The moving element of the transducer is formed by a hollow piece 109 having the shape of a dome covering a cylindrical portion which engages in the air gap 107. So that this piece is at the same time very solid, very light and very rigid, it is for example formed by a carbon fiber fabric embedded in a resin matrix. The upper surface of the dome 109 is covered with a part 110 whose upper surface is substantially flat and which forms the radiative flag of the transducer. It is performed to be itself very light, for example syntactic foam.

Le pavillon 110 se comporte donc comme un piston dont la surface extérieure latérale est cylindrique. Ce piston coulisse dans un cylindre formé par la surface intérieure latérale de la coupelle 103, elle-même sensiblement cylindrique. Ces deux pièces, et plus particulièrement le pavillon 110, sont réalisées de manière à présenter un jeu d'ajustage extrêmement réduit, de l'ordre de 0,2 mm par exemple. On forme ainsi un filtre mécanique qui freine la propagation de l'onde de choc pouvant provenir d'une explosion extérieure éventuelle, en laminant dans cet interstice le fluide dans lequel baigne le pavillon.Pavilion 110 therefore behaves like a piston whose lateral outer surface is cylindrical. This piston slides in a cylinder formed by the lateral inner surface of the cup 103, itself substantially cylindrical. These two parts, and more particularly the roof 110, are made to have an extremely small adjustment play, of the order of 0.2 mm for example. A mechanical filter is thus formed which slows down the propagation of the shock wave that may come from an eventual external explosion, by rolling in this gap the fluid in which the flag is bathed.

Pour protéger le pavillon, la partie supérieure de l'espace central du corps du transducteur est remplie d'un fluide, une huile par exemple, adapté à la fois à cette protection et à la propagation des ondes acoustiques. Pour éviter que cette huile ne s'échappe, l'espace 113 est clos à sa partie supérieure par une membrane 112, qui est fixée sur le pourtour de la coupelle 103.To protect the horn, the upper part of the central space of the transducer body is filled with a fluid, an oil for example, adapted to both this protection and the propagation of acoustic waves. To prevent this oil from escaping, the space 113 is closed at its upper part by a membrane 112, which is fixed on the periphery of the cup 103.

Pour permettre le débattement du dôme et du pavillon, la partie inférieure de l'espace central, opposée à la partie où se situe cette huile, est quant à elle remplie d'air. Pour éviter alors que l'huile contenue dans la partie 113 ne vienne rentrer dans la partie 114 remplie d'air, on utilise une autre membrane d'étanchéité 115, en caoutchouc par exemple, beaucoup plus flexible que la membrane 112 et qui est d'une part fixée sur la paroi latérale extérieure du pavillon 110 et d'autre part sur la paroi latérale intérieure de la coupelle 103. Cette fixation s'effectue par pincement entre cette coupelle 103 et la chemise 102. Pour permettre un débattement libre et correct de cette membrane entre le pavillon et la coupelle, la surface latérale extérieure du pavillon est usinée à ce niveau pour présenter un retrait par rapport à l'ajutage 111, lequel présente le jeu réduit décrit plus haut, et former un espace libre pour la membrane 115.To allow the movement of the dome and flag, the lower part of the central space, opposite the part where the oil is, is filled with air. In order to prevent the oil contained in the part 113 from entering the part 114 filled with air, another sealing membrane 115, made of rubber for example, is used which is much more flexible than the membrane 112 and which is a part fixed on the outer side wall of the roof 110 and secondly on the inner side wall of the cup 103. This attachment is made by pinching between the cup 103 and the shirt 102. To allow a free and correct movement of this membrane between the flag and the cup, the external lateral surface of the flag is machined at this level to present a withdrawal relative to the nozzle 111, which has the reduced clearance described above, and form a free space for the membrane 115.

En outre, pour que le jeu de l'ajutage 111 puisse être maintenu en dépit des efforts de flexion appliqués sur le dôme 109 et le pavillon 112 lors du débattement de ces pièces quand le transducteur fonctionne avec une puissance d'émission importante, cet ensemble est rigidifié en utilisant un jeu de nervures radiales 116 qui sont réparties sur la périphérie intérieure du dôme 109 et viennent se rejoindre en étoile en dessous de la partie inférieure de la tige du champignon formant le noyau 108. Ces nervures viennent coulisser dans des rainures 117 ménagées dans le noyau 108 et dans la première pièce polaire 104. Ces rainures sont relativement larges au niveau du noyau et sont plus étroites au niveau de la pièce polaire pour minimiser la perte de flux magnétique, qui peut être réduite à une valeur très faible de quelques pour-cent.In addition, so that the play of the nozzle 111 can be maintained despite the bending forces applied to the dome 109 and the horn 112 during the movement of these parts when the transducer operates with a large transmitting power, this assembly is stiffened by using a set of radial ribs 116 which are distributed on the inner periphery of the dome 109 and meet in a star below the lower part of the mushroom rod forming the core 108. These ribs slide in grooves 117 formed in the core 108 and in the first pole piece 104. These grooves are relatively wide at the core and are narrower at the pole piece to minimize the loss of magnetic flux, which can be reduced to a very low value. low of a few percent.

Un axe 118 réunit le centre de la partie supérieure du dôme 109 au centre de l'étoile formée par la réunion des nervures 116, en dessous de la face inférieure du noyau 108. Cet axe permet à la fois de rigidifier l'ensemble et d'assurer son centrage vertical par rapport à l'axe du transducteur. Pour assurer cette deuxième fonction, l'axe est fixé par sa partie inférieure au centre d'un ressort plat 119 lui-même fixé circonférenciellement dans la partie inférieure de l'embase 101. Ce ressort, du type connu sous le nom de « flector », est formé d'une rondelle souple et élastique portant des ouvertures circonférentielles permettant de laisser passer l'air librement dans la partie inférieure de l'espace central du transducteur, entre les deux parties délimitées par le plan de ce ressort. Ce ressort assure non seulement le centrage, mais il évite les mouvements de rotation de l'équipage mobile qui viendraient faire frotter les nervures contre les parois des rainures dans lesquelles elles coulissent.An axis 118 joins the center of the upper part of the dome 109 in the center of the star formed by the reunion of the ribs 116, below the lower face of the core 108. This axis makes it possible at the same time to stiffen the assembly and to ensure its vertical centering with respect to the axis of the transducer. To ensure this second function, the axis is fixed by its lower part in the center of a flat spring 119 itself fixed circumferentially in the lower part of the base 101. This spring, of the type known as "flector Is formed of a flexible and resilient washer carrying circumferential openings for allowing air to pass freely in the lower part of the central space of the transducer, between the two parts delimited by the plane of this spring. This spring ensures not only the centering, but it avoids the rotational movements of the moving element that would rub the ribs against the walls of the grooves in which they slide.

L'action motrice qui permet de faire mouvoir l'ensemble dôme/pavillon le long de l'axe du transducteur, pour émettre les ondes acoustiques, est obtenue par l'interaction entre le champ magnétique qui circule entre les pièces polaires et celui délivré par une bobine 120 bobinée sur les flancs latéraux de la partie cylindrique inférieure du dôme 109. Cette bobine est donc plongée dans l'entrefer existant entre les deux pièces polaires, ce qui réalise le schéma classique d'un transducteur électrodynamique, Cette bobine est alimentée par des moyens non représentés sur la figure et qui sont connus dans l'art.The driving action that makes it possible to move the dome / horn assembly along the axis of the transducer, to emit the acoustic waves, is obtained by the interaction between the magnetic field which circulates between the pole pieces and that delivered by a coil 120 wound on the lateral flanks of the lower cylindrical portion of the dome 109. This coil is thus immersed in the air gap existing between the two pole pieces, which realizes the conventional diagram of an electrodynamic transducer, this coil is powered by means not shown in the figure and which are known in the art.

Outre la fonction de rigidification de l'équipage mobile, les nervures 116 servent également de drain thermique sur toute la hauteur de la bobine 120, pour dissiper la chaleur dégagée à ce niveau en la dirigeant vers les autres parties du transducteur.In addition to the stiffening function of the moving element, the ribs 116 also serve as a heat sink over the entire height of the coil 120, to dissipate the heat generated at this level by directing it to the other parts of the transducer.

La partie 114 interne délimitée par le dôme 109, l'embase 101 dont le fond est fermé, la chemise 102 et la membrane d'étanchéité 115 est remplie d'air pour permettre le débattement de l'équipage mobile, comme on l'a vu plus haut.The internal portion 114 delimited by the dome 109, the base 101 whose bottom is closed, the jacket 102 and the sealing membrane 115 is filled with air to allow the movement of the moving assembly, as has been seen above.

Lorsque l'on immerge le transducteur, sous l'effet de la pression hydrostatique l'équipage mobile s'enfonce vers le fond de l'embase 101 en comprimant le ressort 119 et le volume d'air compris dans cette partie 114. Ce mouvement tend bien entendu à modifier les caractéristiques électroacoustiques du transducteur, en particulier en modifiant les positions respectives de la bobine et des pièces polaires,When the transducer is immersed, under the effect of the hydrostatic pressure, the mobile assembly is sinking towards the bottom of the base 101 by compressing the spring 119 and the volume of air included in this portion 114. This movement of course, to modify the electroacoustic characteristics of the transducer, in particular by modifying the respective positions of the coil and the pole pieces,

Pour compenser, au moins en partie, cet effet, on utilise un réservoir de compensation, ou chambre à air, 121 formé d'une poche flexible, en caoutchouc par exemple, soumise à la pression du milieu marin et communicant avec la partie 114 par l'intermédiaire d'un conduit 122. Pour protéger cette chambre à air de l'action des explosions éventuelles se produisant dans le milieu marin, celle-ci est de forme toroïdale et est située dans une autre cavité cylindrique interne 123 qui est délimitée à l'intérieur du transducteur par les parois de la chemise 102 et de la coupelle 103. Cette cavité est donc elle-même toroïdale et fermée et elle entoure l'emplacement du pavillon 110. Pour pouvoir soumettre à la pression marine la chambre à air placée dans cette cavité, on a ménagé sur la paroi extérieure latérale de la chemise 102 des petites ouvertures 124 qui permettent à l'eau de mer de pénétrer dans la cavité 123 et de venir comprimer la chambre à air, De cette manière la chambre à air est protégée contre les agressions extérieures mécaniques par les parois de la cavité où elle est située. En outre le diamètre des ouvertures 124 est prévu pour que les ondes de chocs provenant d'une explosion extérieure éventuelle soit atténuées au passage par ces ouvertures, de manière à ce qu'elles ne présentent aucun danger de surpression au niveau de la chambre à air. Ces ouvertures étant rondes, leur diamètre peut être plus important que l'épaisseur de l'ajutage 111.To compensate, at least in part, for this effect, a compensation tank, or air chamber, 121 formed of a flexible bag, of rubber for example, subjected to the pressure of the marine environment and communicating with the part 114 by 122. To protect this inner tube from the action of any explosions occurring in the marine environment, it is of toroidal shape and is located in another internal cylindrical cavity 123 which is delimited to the interior of the transducer by the walls of the jacket 102 and the cup 103. This cavity is itself toroidal and closed and surrounds the location of the flag 110. To be able to submit to sea pressure the placed air chamber in this cavity, there are formed on the lateral outer wall of the jacket 102 small openings 124 which allow the seawater to enter the cavity 123 and to compress the air chamber, De The inner tube is protected against mechanical external aggression by the walls of the cavity where it is located. In addition the diameter of the openings 124 is provided so that the shock waves from an eventual external explosion is attenuated through these openings, so that they do not present any danger of overpressure at the level of the inner tube. These openings being round, their diameter may be greater than the thickness of the nozzle 111.

Un tel transducteur fonctionne parfaitement, et résiste par exemple à l'explosion d'une tonne de TNT située à 30m de celui-ci.Such a transducer works perfectly, and resists for example the explosion of a ton of TNT located 30m from it.

Toutefois, en raison de l'évolution constante des techniques, on est amené à augmenter de plus en plus la puissance acoustique délivrée dans les transducteur de ce type, ce qui se heurte à des limites technologiques provenant plus particulièrement des capacités de dissipation thermique de la chaleur dégagée dans le bobinage de commande de l'équipage mobile.However, because of the constant evolution of the techniques, it is necessary to increase more and more the acoustic power delivered in the transducer of this type, which faces technological limitations deriving more particularly from the heat dissipation capabilities of the heat released in the control coil of the moving equipment.

En effet, le courant important qui circule alors dans la bobine 120 entraîne un fort échauffement local qui ne peut plus être dissipé correctement par les moyens prévus jusqu'à ce jour, en particulier par les ailettes 116.Indeed, the large current which then flows in the coil 120 causes a strong local heating which can not be dissipated properly by the means provided to date, in particular by the fins 116.

Cet échauffement finit par entraîner une détérioration de la bobine, en particulier au niveau de sa base, c'est à dire du côté opposé au pavillon. Cette détérioration est irréversible et nécessite, lorsqu'elle se produit, une réparation coûteuse.This heating ends up causing deterioration of the coil, especially at its base, that is to say on the opposite side to the flag. This deterioration is irreversible and requires, when it occurs, an expensive repair.

Pour augmenter la dissipation thermique à ce niveau, et éviter ainsi cette détérioration, l'invention propose un transducteur électrodynamique pour acoustique sous-marine, du type comprenant un corps muni de pièces polaires définissant un entrefer, un équipage mobile muni d'un dôme prolongé par un cylindre supportant un bobinage coulissant dans cet entrefer, une membrane flexible assurant l'étanchéité entre l'équipage mobile et le corps en déterminant une partie interne emplie d'air, et un pavillon surmontant ledit dôme et coulissant dans ledit corps en formant avec celui-ci un ajutage dont la valeur du jeu est fixée de manière à permettre de protéger ladite membrane contre les ondes de choc provenant d'explosions extérieures au transducteur en laminant ces ondes de choc dans ledit ajutage, principalement caractérisé en ce que l'une des dites pièces polaires est muni d'au moins une ouverture permettant la circulation de l'air à l'intérieur de la partie interne pour refroidir efficacement ledit bobinage.To increase the heat dissipation at this level, and thus avoid this deterioration, the invention proposes an electrodynamic transducer for underwater acoustics, of the type comprising a body provided with pole pieces defining an air gap, a moving element provided with an extended dome by a cylinder supporting a sliding winding in this air gap, a flexible membrane ensuring the seal between the mobile equipment and the body by determining an inner part filled with air, and a flag overlying said dome and sliding in said body forming with it is a nozzle whose play value is set so as to protect said membrane against shock waves from explosions external to the transducer by laminating these shock waves in said nozzle, mainly characterized in that one said pole pieces is provided with at least one opening for the circulation of air inside the inner part for effectively cooling said winding.

Selon une autre caractéristique, il comprend en outre une masse conductrice de la chaleur située entre les dites pièces polaires pour drainer vers l'extérieur du transducteur la chaleur dégagée par le bobinage.According to another characteristic, it further comprises a conductive mass of the heat located between said pole pieces for draining the heat generated by the winding towards the outside of the transducer.

Selon une autre caractéristique, il comprend en outre un ensemble d'aimants placés entre les pièces polaires, caractérisé en ce qu'il comprend en outre un ensemble de masses conductrices de la chaleur intercalées entre les aimants.According to another characteristic, it further comprises a set of magnets placed between the pole pieces, characterized in that it further comprises a set of heat conductive masses interposed between the magnets.

Selon une autre caractéristique, lesdites masses conductrices de la chaleur sont réalisées en aluminium.According to another characteristic, said heat-conducting masses are made of aluminum.

D'autres particularités et avantages de l'invention apparaîtront clairement dans la description suivante, présenté à titre d'exemple non limitatif au regard des figures annexées qui représentent :

  • les figures 1 et 2, des vues en coupe d'un transducteur selon l'art antérieur; et
  • les figures 3 et 4 des vues en coupe selon les mêmes conditions d'un transducteur du même type modifié selon l'invention.
Other features and advantages of the invention will become clear in the following description, presented by way of non-limiting example with reference to the appended figures which represent:
  • the Figures 1 and 2 sectional views of a transducer according to the prior art; and
  • the Figures 3 and 4 sectional views under the same conditions of a transducer of the same type modified according to the invention.

Une analyse poussée du fonctionnement des transducteurs selon l'art antérieur a montré que le mauvais refroidissement de la bobine 120, surtout dans sa partie inférieure, provenait d'une part de ce que la conduction thermique vers le haut de la bobine était insuffisante, et d'autre part qu'il y avait très peu de dissipation locale dans le bas de la bobine par conduction à ce niveau. En effet, la base de la bobine est placée dans une partie 130 de la cavité interne 114, qui est étroite et confinée. De cette manière la masse d'air emprisonnée à ce niveau ne peut pas se renouveler pour permettre un refroidissement efficace par convection, elle est trop faible pour absorber elle-même une quantité suffisante de chaleur, et les dimensions latérales sont néanmoins trop grandes pour permettre une évacuation de la chaleur vers les pièces polaires par conduction directe à travers cette masse d'air. L'invention propose donc de supprimer le confinement de l'air dans cette partie 130 où est plongée la partie inférieure de la bobine 120 en pratiquant des trous 131 dans le circuit magnétique 104. Ces trous, qui sont dans cet exemple de réalisation sensiblement verticaux, mettent donc en communication la partie 130 de la cavité 114 avec la partie 126 de cette même cavité, située en bas du transducteur sous le noyau 108. La communication supplémentaire créée ainsi entre la partie 125 de la cavité 114, située au-dessus de ce noyau 108 et cette partie 126, permet une circulation de l'air. Celui-ci s'étant échauffé au contact de la bobine 120 vient remonter dans la partie 125, se refroidit par contact avec les différentes pièces massives du transducteur, puis revient dans la partie 126 de la cavité 114 en redescendant par les différents orifices situés dans la partie centrale du transducteur.A thorough analysis of the operation of the transducers according to the prior art has shown that the bad cooling of the coil 120, especially in its lower part, originated, on the one hand, from the fact that the thermal conduction towards the top of the coil was insufficient, and on the other hand, there was very little local dissipation in the bottom of the coil by conduction at this level. Indeed, the base of the coil is placed in a portion 130 of the internal cavity 114, which is narrow and confined. In this way the mass of air trapped at this level can not be renewed to allow efficient cooling by convection, it is too weak to absorb itself a sufficient amount of heat, and the lateral dimensions are nevertheless too large to allow an evacuation of the heat towards the polar parts by direct conduction through this mass of air. The invention therefore proposes to eliminate the confinement of the air in this part 130 where the lower part of the coil 120 is immersed by forming holes 131 in the magnetic circuit 104. These holes, which are in this embodiment substantially vertical, therefore put in communication the portion 130 of the cavity 114 with the portion 126 of the same cavity, located at the bottom of the transducer under the core 108. The communication additional created thus between the portion 125 of the cavity 114, located above the core 108 and this portion 126, allows a flow of air. The latter having heated in contact with the coil 120 comes up in the part 125, cools by contact with the different massive parts of the transducer, then returns to the portion 126 of the cavity 114 down through the various orifices located in the central part of the transducer.

Pour faciliter la réalisation de ces ouvertures 131, l'invention propose, dans l'exemple de réalisation représenté sur les figures 3 et 4, d'usiner la partie inférieure du boîtier 101, à l'intérieur de celui-ci au niveau de la partie 126 de la cavité 114, en fraisant l'intérieur de celle-ci de manière à dégager un épaulement circulaire 132 afin que les trous 131 puissent être eux-mêmes usinés verticalement tout en débouchant dans la partie 126 de la cavité 114.To facilitate the production of these openings 131, the invention proposes, in the exemplary embodiment shown on the Figures 3 and 4 , machining the lower portion of the housing 101, inside thereof at the portion 126 of the cavity 114, milling the interior thereof so as to disengage a circular shoulder 132 so that the holes 131 may themselves be machined vertically while opening into the portion 126 of the cavity 114.

Comme en définitive la chaleur dégagée finit par se dissiper dans l'eau de mer qui entoure le transducteur, tout au moins après un certain temps de fonctionnement, l'invention propose, pour améliorer le transfert de la chaleur entre l'intérieur du transducteur, plus particulièrement depuis le volume d'air qui circule au niveau de la partie 130 de la cavité 114, de placer entre les aimants 106 des masses métalliques 135 qui forment des drains thermiques entre l'intérieur du transducteur et le milieu extérieur, par l'intermédiaire de la chemise 102. Ces masses métalliques sont usinées pour offrir un maximum de chemin thermique à la chaleur dégagée en occupant le plus de place possible entre les aimants. Elles sont fabriquées dans un matériau qui soit le plus possible conducteur de la chaleur tout en restant suffisamment léger pour ne pas alourdir la masse du transducteur. Parmi les matériaux les plus convenables à cet usage, on citera l'aluminium. Elles sont maintenues, par exemple par collage, sur la pièce polaire 104, ou éventuellement par pincement entre les pièces polaires 104 et 105 de la même manière que les aimants 106.As finally the heat released eventually dissipates in the sea water surrounding the transducer, at least after a certain time of operation, the invention proposes, to improve the transfer of heat between the inside of the transducer, more particularly since the volume of air flowing at the portion 130 of the cavity 114, to place between the magnets 106 metal masses 135 which form thermal drains between the inside of the transducer and the external environment, by the intermediate of the shirt 102. These metal masses are machined to provide a maximum thermal path to the heat released by occupying as much space as possible between the magnets. They are made of a material that is as much as possible heat conductor while remaining light enough not to weigh down the mass of the transducer. Among the most suitable materials for this use include aluminum. They are held, for example by gluing, on the pole piece 104, or possibly by pinching between the pole pieces 104 and 105 in the same manner as the magnets 106.

L'expérience a montré qu'un transducteur réalisé de cette manière peut supporter un courant pouvant être au moins 4 fois supérieur au courant admissible dans un transducteur selon l'art connu, sans qu'il soit nécessaire d'apporter aucune modification au reste du transducteur, en particulier à la bobine, et en obtenant des performances identiques, sans aucune dégradation.Experience has shown that a transducer made in this way can withstand a current that can be at least 4 times higher than the admissible current in a transducer according to the prior art, without it being necessary to make any modification to the rest of the transducer, in particular to the coil, and obtaining identical performance without any degradation.

Claims (4)

  1. Electrodynamic transducer for underwater acoustics, of the type comprising a body (101-103) equipped with pole pieces (104, 105) defining an air-gap (107), a mobile equipment equipped with a dome (109) extended by a cylinder supporting a winding (120) that slides in this air-gap, a flexible membrane (115) ensuring the seal between the mobile equipment and the body, determining an internal part (114) filled with air, and a horn (110) mounted on top of said dome (109) and sliding in said body, forming a nozzle with said body, the value of the play (111) of which is fixed so as to enable the protection of said membrane against the shock waves coming from explosions external to the transducer by throttling these shock waves in said nozzle, characterized in that one of said pole pieces (104) is provided with at least one opening (131) allowing the air to flow inside the internal part (114) in order to cool said winding effectively.
  2. Transducer according to Claim 1, characterized in that it furthermore comprises at least one thermally conductive mass (135) situated between said pole pieces (104, 105) to drain the heat given off by the winding (120) towards the exterior of the transducer.
  3. Transducer according to Claim 2, which comprises a set of magnets (106) located between the pole pieces (104-105), characterized in that it furthermore comprises a set of thermally conductive masses (135) inserted between the magnets.
  4. Transducer according to either of Claims 2 and 3, characterized in that said thermally conductive masses (135) are made of aluminium.
EP01401347A 2000-05-26 2001-05-22 Electrodynamic transducer for underwater acoustic Expired - Lifetime EP1157751B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0006766 2000-05-26
FR0006766A FR2809580B1 (en) 2000-05-26 2000-05-26 ELECTRODYNAMIC TRANSDUCER FOR UNDERWATER ACOUSTICS

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EP1157751A1 EP1157751A1 (en) 2001-11-28
EP1157751B1 true EP1157751B1 (en) 2009-05-06

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EP (1) EP1157751B1 (en)
DE (1) DE60138588D1 (en)
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FR3015785B1 (en) * 2013-12-20 2015-12-25 Thales Sa COMPACT OMNIDIRECTIONAL ANTENNA FOR SONAR TEMP
CN108301820B (en) * 2018-05-02 2023-04-21 重庆科技学院 Acoustic wave detection device in stratum borehole and detection method thereof

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FR2809580A1 (en) 2001-11-30
DE60138588D1 (en) 2009-06-18
US20020034124A1 (en) 2002-03-21
FR2809580B1 (en) 2002-08-30
US6515940B2 (en) 2003-02-04
EP1157751A1 (en) 2001-11-28

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