EP0881001A1 - Electrodynamic transducer for underwater acoustics - Google Patents

Electrodynamic transducer for underwater acoustics Download PDF

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Publication number
EP0881001A1
EP0881001A1 EP98401205A EP98401205A EP0881001A1 EP 0881001 A1 EP0881001 A1 EP 0881001A1 EP 98401205 A EP98401205 A EP 98401205A EP 98401205 A EP98401205 A EP 98401205A EP 0881001 A1 EP0881001 A1 EP 0881001A1
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EP
European Patent Office
Prior art keywords
transducer
dome
moving
pavilion
air chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP98401205A
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German (de)
French (fr)
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EP0881001B1 (en
Inventor
Vito Thomson-CSF Prop.Int.dept.prot.cons. Suppa
Jean Thomson-CSF Prop.Int.dept.prot.con Bertheas
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Thales Underwater Systems SAS
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Thales Underwater Systems SAS
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Publication of EP0881001A1 publication Critical patent/EP0881001A1/en
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/004—Mounting transducers, e.g. provided with mechanical moving or orienting device
    • G10K11/006—Transducer mounting in underwater equipment, e.g. sonobuoys
    • 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
    • B06B1/04—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism
    • B06B1/045—Methods 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 type electrodynamics which allow waves to be emitted within the sea acoustic, more particularly sound waves. These transducers are particularly useful in sonar technique.
  • transducers of the type electrodynamics which include a horn driven by a coil mobile located in an air gap. These transducers of this type are quite similar to the well-known loudspeakers in musical acoustics.
  • the transducer can withstand the explosions that sometimes occur in applications particular.
  • the effect of such an underwater explosion results in applying a hydrostatic pressure step to the transducer and acceleration. This level is easily destructive at the level of roof and the waterproofing membrane between the roof and the housing transducer.
  • a technique known to resist such explosions consists of placing a dome over the roof of such a transducer pierced with holes and itself covered with a membrane. Each of these holes therefore forms a valve which allows the corresponding vibrations to pass to acoustic signals emitted by the transducer and does not let through pressure peaks from possible explosions.
  • Such system has the disadvantage of increasing the volume and mass of the transducer, and decrease the noise level it can issue.
  • the invention proposes a electrodynamic transducer for underwater acoustics, of the type comprising a body provided with pole pieces defining an air gap, a mobile equipment provided with a dome extended by a cylinder supporting a sliding winding in this air gap, and a flexible membrane ensuring the seal between the moving part and the body, mainly characterized in that it further comprises a pavilion surmounting said dome and sliding in said body, forming a nozzle therewith whose play value is fixed so as to protect said clearance shock wave membrane from external explosions to the transducer by laminating these shock waves in said nozzle.
  • the mobile assembly comprises in in addition to a set of radial ribs fixed on one side to the wall interior of this moving assembly and joined on the other side in a star shape to increase the stiffness of this mobile equipment and its resistance to said shock wave.
  • the transducer comprises in besides a spring fixed on its periphery to the lower part of the body and connected in its center to the center of the star formed by the union of the said ribs, this spring making it possible to center the following moving assembly the vertical axis.
  • it further comprises a peripheral cavity formed in the body and connected to the external environment by at least one perforation and a toric and elastic air chamber contained in this peripheral cavity connected to the lower cavity defined by the body and the moving crew to compensate for the effects of the hydrostatic pressure due to immersion; the height difference between the roof and this air chamber used to hold the crew mobile in a neutral position.
  • the transducer according to the invention shown in the two appended figures includes a body formed by a base 101 on which fits a 102 shirt surmounted by a cup 103. These different pieces fit into each other of so as to define cylindrical cavities of revolution around the axis of the transducer, into which the other parts are inserted forming this transducer.
  • a first cylindrical cavity delimited between the base and the shirt allows to maintain a magnetic circuit formed of a first and second pole pieces 104 and 105 in the form of crowns centered on the axis of the transducer.
  • the first pole piece 104 is L-shaped with the inner branch of the L protruding inside the central chamber of the transducer.
  • the second room polar 105 is in the shape of a flat washer. Both are maintained separated by a set of magnets 106 on which they are clamped by the fitting of the shirt 102 in the base 101. This is obtained way a magnetic circuit which is only interrupted by a thin air gap 107 having the shape of a cylinder centered on the axis of the transducer and coming close to the inner side surface of the dish 103.
  • the central space of the transducer body forms a second cylindrical cavity in which a core 108, in the form of mushroom, comes to be embedded by its central rod in the opening central circular piece of the pole piece 104.
  • the movable element of the transducer is formed by a part hollow 109 having the shape of a dome covering a cylindrical part which comes to engage in the air gap 107. So that this part 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. According to the invention, the upper surface of the dome 109 is covered with a part 110 whose upper surface is substantially flat and which forms the radiative horn of the transducer. It is realized, to be itself very light, for example in syntactic foam.
  • the pavilion 110 therefore behaves like a piston whose lateral outer surface is cylindrical. This piston slides in a cylinder formed by the lateral interior surface of the cup 103, itself substantially cylindrical. According to the invention, these two parts, and more particularly the pavilion 110, are made so as to have an extremely small adjustment clearance, of the order of 0.2 mm for example. We thus form a mechanical filter which slows the propagation shock wave that can come from an external explosion possible, by laminating in this interstice the fluid in which the flag.
  • the upper part of the space center of the transducer body is filled, in a known manner, with a fluid, an oil for example, suitable for both this protection and the propagation of acoustic waves.
  • a fluid an oil for example, suitable for 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 this is located oil is filled with air.
  • the lateral surface exterior of the pavilion is machined at this level to provide a recess compared to nozzle 111, which presents the reduced clearance described more high, and form a free space for the membrane 115.
  • the invention proposes to stiffen this set using a set of radial ribs 116 which are distributed over the inner periphery of the dome 109 and come to join in a star below the lower part of the stem of the mushroom forming the core 108. These ribs come slide in grooves 117 made in the core 116 and in the first pole piece 104. These grooves are relatively wide at the level of the core and are narrower at the pole piece level for minimize loss of magnetic flux, which can be reduced to a value very low by 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 union of the ribs 116, in below the underside of the core 108.
  • This axis allows both stiffen the assembly and 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 the "flector” is formed of a flexible and elastic washer with circumferential openings allowing free passage of air in the lower part of the central space of the transducer, between the two parts delimited by the plan of this spring. This spring not only ensures centering, but it avoids the rotational movements of the moving part which would come rub the ribs against the walls of the grooves in which they slide.
  • the driving action that makes the whole move dome / flag along the axis of the transducer, to emit the waves acoustic, 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 sides of the lower cylindrical part of the dome 109.
  • This coil is therefore immersed in the air gap existing between the two pole pieces, which achieves the classic pattern of a 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 full-length heat sink of the coil 120, to dissipate the heat given off at this level by pointing to the other parts of the transducer.
  • the internal part 114 delimited by the dome 109, the base 101 with the bottom closed, the jacket 102 and the waterproofing membrane 115 is filled with air to allow the movement of the moving part, as we saw above.
  • the moving part sinks towards the bottom of the base 101 by compressing the spring 119 and the volume of air included in this part 114. This movement naturally tends to modify the electroacoustic characteristics of the transducer, in particular modifying the respective positions of the coil and the pole pieces.
  • a compensation tank, or air chamber, 121 formed of a pocket flexible, in rubber for example, subject to environmental pressure marine and communicating with Part 114 through a conduit 122.
  • this is toroidal in shape and is located in another cavity internal cylindrical 123 which is delimited inside the transducer by the walls of the jacket 102 and the cup 103. This cavity is so itself toroidal and closed and it surrounds the location of the pavilion 110.
  • the transducers of this type being generally intended for operate in such a way as to emit the acoustic waves downwards, therefore in the opposite position to that shown in FIG. 1, the movement of the moving part towards the bottom of the body 101 under the effect hydrostatic pressure is then thwarted simultaneously by the action of the spring 119, the action of gravity on the whole of the moving part, and the action of the hydrostatic pressure on the chamber air 121.
  • the invention proposes to size these different parts in such a way that there is a difference ⁇ h between the plane of the exterior surface of the roof and the average position of the air chamber; this distance being such that the difference in hydrostatic pressure between this surface and the air chamber, due to the difference in immersions, balances the weight of the moving assembly.
  • This formula allows, for a given construction, to obtain the maximum value of the immersion, and for a maximum value desired immersion, to obtain the volume value of the chamber to air, and therefore its sizing as well as that of the parts which contain.
  • a transducer to be immersed at a depth of 30 m must have an air chamber whose volume is substantially equal to 3 times the volume of air in the rest of the transducer.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Electromagnetism (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)

Abstract

The electro-dynamic transducer comprises a body (101-103) which has polar pieces (105,105) that define a gap (107) and a moving armature with a dome (109). The dome is extended by a cylinder supporting a coil (120) which slides in the gap. A flexible membrane seals between the body and the armature. Above the dome is a bell (110) which slides in the body of the transducer, having a degree of play between the two which is extremely small. This allows a reduction in the effects of a shock wave arising from an external explosion.

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 type electrodynamics which allow waves to be emitted within the sea acoustic, 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.We use towed fish in underwater acoustics with various electronic devices and transducers able to 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 entrainé par une bobine mobile située dans un entrefer. Ces transducteurs de ce type sont tout à fait semblables aux hauts-parleurs bien connus en acoustique musicale.We know that at low frequency, typically between 10 Hz and 1 kHz, to be able to emit sufficient acoustic power, move large bodies of water, which requires a itself significant displacement of the active face of the transducer. This leads in this case to generally use transducers of the type electrodynamics, which include a horn driven by a coil mobile 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 entraíne 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.To be able to obtain sound power frequently required in some applications, given the noise level at reach, which can reach 150 dB at 10 Hz, we are led to use relatively large transducers. This causes constraints, both in volume and in weight, because the transducer should be submerged in the sea while being placed in a fish which must sail to a predetermined immersion.

En outre, il est fréquemment requis que le transducteur puisse résister aux explosions qui se produisent parfois dans des applications particulières. L'effet d'une telle explosion sous-marine se traduit par l'application sur le transducteur d'un échelon de pression hydrostatique et d'accélération. Cet échelon est facilement destructeur au niveau du pavillon et de la membrane d'étanchéité entre le pavillon et le boítier du transducteur. In addition, it is frequently required that the transducer can withstand the explosions that sometimes occur in applications particular. The effect of such an underwater explosion results in applying a hydrostatic pressure step to the transducer and acceleration. This level is easily destructive at the level of roof and the waterproofing membrane between the roof and the housing transducer.

On connaít plus particulièrement du brevet US 4 466 083 un transducteur électrodynamique pour acoustique sous-marine qui permet effectivement de délivrer une puissance acoustique importante, mais qui est essentiellement conçu pour éviter les problèmes dus à la dissipation thermique correspondant aux pertes de conversion électrique/ acoustique. La structure de ce transducteur ne lui permet pas de résister aux explosions sous-marine. Le cas échéant, celles-ci le rendrait rapidement inutilisable en déchirant sa membrane, en écrasant son dôme et en détériorant ses ressorts de rappel.We know more particularly from US Patent 4,466,083 a electrodynamic transducer for underwater acoustics which allows actually deliver significant acoustic power, but which is basically designed to avoid problems due to dissipation thermal corresponding to electrical conversion losses / acoustic. The structure of this transducer does not allow it to resist to underwater explosions. If so, these would make it quickly unusable by tearing its membrane, crushing its dome and deteriorating its return springs.

Une technique connue pour résister à de telles explosions consiste à placer par dessus le pavillon d'un tel transducteur un dôme percé de trous et lui-même recouvert d'une membrane . Chacun de ces trous forme donc un clapet qui laisse passer les vibrations correspondant aux signaux acoustiques émis par le transducteur et ne laisse pas passer les pics de pression provenant des explosions éventuelles. Un tel système présente toutefois le désavantage d'augmenter le volume et la masse du transducteur, et de diminuer le niveau sonore qu'il peut délivrer.A technique known to resist such explosions consists of placing a dome over the roof of such a transducer pierced with holes and itself covered with a membrane. Each of these holes therefore forms a valve which allows the corresponding vibrations to pass to acoustic signals emitted by the transducer and does not let through pressure peaks from possible explosions. Such system has the disadvantage of increasing the volume and mass of the transducer, and decrease the noise level it can issue.

Pour pallier ces inconvénients, 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, et une membrane flexible assurant l'étanchéité entre l'équipage mobile et le corps, principalement caractérisé en ce qu'il comprend en outre 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.To overcome these drawbacks, the invention proposes a electrodynamic transducer for underwater acoustics, of the type comprising a body provided with pole pieces defining an air gap, a mobile equipment provided with a dome extended by a cylinder supporting a sliding winding in this air gap, and a flexible membrane ensuring the seal between the moving part and the body, mainly characterized in that it further comprises a pavilion surmounting said dome and sliding in said body, forming a nozzle therewith whose play value is fixed so as to protect said clearance shock wave membrane from external explosions to the transducer by laminating these shock waves in said nozzle.

Selon une autre caractéristique, l'équipage mobile comporte en outre un ensemble de nervures radiales fixées d'un côté sur la paroi intérieure de cet équipage mobile et réunies de l'autre côté en étoile pour augmenter la raideur de cet équipage mobile et sa résistance aux dites onde de choc. According to another characteristic, the mobile assembly comprises in in addition to a set of radial ribs fixed on one side to the wall interior of this moving assembly and joined on the other side in a star shape to increase the stiffness of this mobile equipment and its resistance to said shock wave.

Selon une autre caractéristique, le transducteur comporte en outre un ressort fixé sur sa périphérie à la partie inférieure du corps et relié en son centre au centre de l'étoile formée par la réunion des dites nervures, ce ressort permettant de centrer l'équipage mobile suivant l'axe vertical.According to another characteristic, the transducer comprises in besides a spring fixed on its periphery to the lower part of the body and connected in its center to the center of the star formed by the union of the said ribs, this spring making it possible to center the following moving assembly the vertical axis.

Selon une autre caractéristique, il comprend en outre une cavité périphérique ménagée dans le corps et reliée au milieu extérieur par au moins une perforation et une chambre à air torique et élastique contenue dans cette cavité périphérique reliée à la cavité inférieure définie par le corps et l'équipage mobile pour compenser les effets de la pression hydrostatique due à l'immersion; la différence de hauteur entre le pavillon et cette chambre à air permettant de maintenir l'équipage mobile dans une position neutre.According to another characteristic, it further comprises a peripheral cavity formed in the body and connected to the external environment by at least one perforation and a toric and elastic air chamber contained in this peripheral cavity connected to the lower cavity defined by the body and the moving crew to compensate for the effects of the hydrostatic pressure due to immersion; the height difference between the roof and this air chamber used to hold the crew mobile in a neutral position.

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

  • la figure 1, une vue en coupe verticale de la moitié d'un transducteur selon l'invention; et
  • la figure 2, une vue horizontale selon le plan AA du transducteur de la figure 1.
Other features and advantages of the invention will appear clearly in the following description, given by way of nonlimiting example with reference to the appended figures which represent:
  • Figure 1, a vertical sectional view of half of a transducer according to the invention; and
  • FIG. 2, a horizontal view along the plane AA of the transducer of FIG. 1.

Le transducteur selon l'invention représenté sur les deux figures 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'emboítent 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.The transducer according to the invention shown in the two appended figures includes a body formed by a base 101 on which fits a 102 shirt surmounted by a cup 103. These different pieces fit into each other of so as to define cylindrical cavities of revolution around the axis of the transducer, into which the other parts are inserted forming this 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 shirt allows to maintain a magnetic circuit formed of a first and second pole pieces 104 and 105 in the form of crowns centered on the axis of the transducer. The first pole piece 104 is L-shaped with the inner branch of the L protruding inside the central chamber of the transducer. The second room polar 105 is in the shape of a flat washer. Both are maintained separated by a set of magnets 106 on which they are clamped by the fitting of the shirt 102 in the base 101. This is obtained way a magnetic circuit which is only interrupted by a thin air gap 107 having the shape of a cylinder centered on the axis of the transducer and coming close to the inner side surface of the dish 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 core 108, in the form of mushroom, comes to be embedded by its central rod in the opening central circular piece of the pole piece 104. The lower part of the head of the nucleus, of substantially hemispherical shape, rests on the part upper part of the 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. Selon l'invention, 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 movable element of the transducer is formed by a part hollow 109 having the shape of a dome covering a cylindrical part which comes to engage in the air gap 107. So that this part 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. According to the invention, the upper surface of the dome 109 is covered with a part 110 whose upper surface is substantially flat and which forms the radiative horn of the transducer. It is realized, to be itself very light, for example in 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. Selon l'invention, 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.The pavilion 110 therefore behaves like a piston whose lateral outer surface is cylindrical. This piston slides in a cylinder formed by the lateral interior surface of the cup 103, itself substantially cylindrical. According to the invention, these two parts, and more particularly the pavilion 110, are made so as to have an extremely small adjustment clearance, of the order of 0.2 mm for example. We thus form a mechanical filter which slows the propagation shock wave that can come from an external explosion possible, by laminating in this interstice the fluid in which the flag.

Pour protéger le pavillon, la partie supérieure de l'espace central du corps du transducteur est remplie, de manière connue, 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 pavilion, the upper part of the space center of the transducer body is filled, in a known manner, with a fluid, an oil for example, suitable for both this protection and the propagation of acoustic waves. To prevent this oil from escapes, 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 ce 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. Dans cet exemple de réalisation, 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 dome and the pavilion to travel, the lower part of the central space, opposite the part where this is located oil is filled with air. To prevent the oil contained therein in part 113 does not come into part 114 filled with air, we uses another waterproofing membrane 115, made of rubber by example, much more flexible than membrane 112 and which is of a part fixed on the outer side wall of the pavilion 110 and on the other hand on the inner side wall of the cup 103. In this example of realization, this fixing is carried out by pinching between this cup 103 and the shirt 102. To allow free and correct travel of this membrane between the roof and the cup, the lateral surface exterior of the pavilion is machined at this level to provide a recess compared to nozzle 111, which presents the reduced clearance described more high, and form a free space for the membrane 115.

A titre de variante, pour éviter que l'huile contenue dans la cavité 113 ne vienne imprégner la mousse syntactique 110 en augmentant sa masse, on peut prévoir d'étanchéifier la surface extérieure de ce pavillon en la recouvrant d'une fine couche composée d'un tissu de fibre de carbone noyé dans une matrice en résine.Alternatively, to prevent the oil contained in the cavity 113 does not impregnate the syntactic foam 110 in increasing its mass, we can plan to seal the surface exterior of this pavilion by covering it with a thin compound layer carbon fiber fabric embedded in a resin matrix.

En outre, pour que le jeu de l'ajustage 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, l'invention propose de rigidifier cet ensemble 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 116 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-cents. In addition, so that the adjustment clearance 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 significant transmission power, the invention proposes to stiffen this set using a set of radial ribs 116 which are distributed over the inner periphery of the dome 109 and come to join in a star below the lower part of the stem of the mushroom forming the core 108. These ribs come slide in grooves 117 made in the core 116 and in the first pole piece 104. These grooves are relatively wide at the level of the core and are narrower at the pole piece level for minimize loss of magnetic flux, which can be reduced to a value very low by 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 union of the ribs 116, in below the underside of the core 108. This axis allows both stiffen the assembly and ensure its vertical centering with respect to the axis of the transducer. To perform 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 the "flector", is formed of a flexible and elastic washer with circumferential openings allowing free passage of air in the lower part of the central space of the transducer, between the two parts delimited by the plan of this spring. This spring not only ensures centering, but it avoids the rotational movements of the moving part which would come 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 the whole move dome / flag along the axis of the transducer, to emit the waves acoustic, 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 sides of the lower cylindrical part of the dome 109. This coil is therefore immersed in the air gap existing between the two pole pieces, which achieves the classic pattern of a 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 assembly, the ribs 116 also serve as a full-length heat sink of the coil 120, to dissipate the heat given off at this level by pointing 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 part 114 delimited by the dome 109, the base 101 with the bottom closed, the jacket 102 and the waterproofing membrane 115 is filled with air to allow the movement of the moving part, as we saw 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 moving part sinks towards the bottom of the base 101 by compressing the spring 119 and the volume of air included in this part 114. This movement naturally tends to modify the electroacoustic characteristics of the transducer, in particular 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 communiquant avec la partie 114 par l'intermédiaire d'un conduit 122. Selon l'invention, 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, we use a compensation tank, or air chamber, 121 formed of a pocket flexible, in rubber for example, subject to environmental pressure marine and communicating with Part 114 through a conduit 122. According to the invention, to protect this air chamber from the action of any explosions occurring in the marine environment, this is toroidal in shape and is located in another cavity internal cylindrical 123 which is delimited inside the transducer by the walls of the jacket 102 and the cup 103. This cavity is so itself toroidal and closed and it surrounds the location of the pavilion 110. In order to be able to subject the marine pressure to the chamber air placed in this cavity, we have created on the lateral outer wall of the shirt 102 of the small openings 124 which allow the water to sea to enter cavity 123 and compress the chamber air. In this way the air chamber is protected against attack mechanical exterior by the walls of the cavity where it is located. In besides the diameter of the openings 124 is provided so that the waves of shocks from a possible external explosion be attenuated at passage through these openings, so that they do not present no danger of overpressure in the air chamber. These openings being round, their diameter can be larger than the thickness of the nozzle 111.

Les transducteurs de ce type étant généralement prévu pour fonctionner de manière à émettre les ondes acoustiques vers le bas, donc dans la position inverse de celle représentée sur la figure 1, le mouvement de l'équipage mobile vers le fond du corps 101 sous l'effet de la pression hydrostatique est alors contrarié simultanément par l'action du ressort 119, l'action de la pesanteur sur l'ensemble de l'équipage mobile, et l'action de la pression hydrostatique sur la chambre à air 121.The transducers of this type being generally intended for operate in such a way as to emit the acoustic waves downwards, therefore in the opposite position to that shown in FIG. 1, the movement of the moving part towards the bottom of the body 101 under the effect hydrostatic pressure is then thwarted simultaneously by the action of the spring 119, the action of gravity on the whole of the moving part, and the action of the hydrostatic pressure on the chamber air 121.

Pour équilibrer dans cette position l'équipage mobile dans une position telle que le ressort 119 soit dans sa position de repos, la pression sur la surface du pavillon équilibrant alors la pression sur la chambre à air, l'invention propose de dimensionner ces différentes pièces de telle manière qu'il y ait une différence Δh entre le plan de la surface extérieure du pavillon et la position moyenne de la chambre à air; cette distance étant telle que la différence de pression hydrostatique entre cette surface et la chambre à air, dûe à la différence des immersions, équilibre le poids de l'équipage mobile. Le calcul montre qu'avec une valeur M pour la masse de l'équipage mobile, une surface S pour la surface émissive du pavillon et une masse volumique ρ pour le milieu marin, cette différence d'altitude est donnée par : Δh = M/Sρ To balance in this position the moving element in a position such that the spring 119 is in its rest position, the pressure on the surface of the roof then balancing the pressure on the air chamber, the invention proposes to size these different parts in such a way that there is a difference Δh between the plane of the exterior surface of the roof and the average position of the air chamber; this distance being such that the difference in hydrostatic pressure between this surface and the air chamber, due to the difference in immersions, balances the weight of the moving assembly. The calculation shows that with a value M for the mass of the moving part, a surface S for the emissive surface of the flag and a density ρ for the marine environment, this difference in altitude is given by: Δh = M / Sρ

En prenant des valeurs, courantes pour un tel pavillon, de 200 mm de diamètre et de 1,5 kilos, la différence d'altitude est alors égale à 48 mm.Taking values, common for such a pavilion, of 200 mm in diameter and 1.5 kilos, the difference in altitude is then equal to 48 mm.

Au fur et à mesure que l'on immerge le transducteur, la position de l'équipage mobile reste alors sensiblement fixe alors que la chambre à air se rétracte. Ce phénomène se déroule jusqu'à ce que la chambre à air soit totalement rétractée. On est alors à une immersion maximale à partir de laquelle il ne peut plus y avoir de compensation de la pression hydrostatique. En posant VT = le volume d'air dans le transducteur, Vc = le volume d'air dans la chambre, pmax la pression à l'immersion maximale et ρmin celle à l'immersion minimale, la relation entre ces valeurs est données par : pmax VT = ρmin (VT + VC) As the transducer is immersed, the position of the moving assembly then remains substantially fixed while the air chamber retracts. This phenomenon takes place until the air chamber is fully retracted. We are then at a maximum immersion from which there can no longer be any compensation for the hydrostatic pressure. By setting V T = the air volume in the transducer, V c = the air volume in the chamber, p max the pressure at maximum immersion and ρ min that at minimum immersion, the relationship between these values is given by: p max V T = ρ min (V T + V C )

Cette formule permet, pour une construction donnée, d'obtenir la valeur maximale de l'immersion, et pour une valeur maximale d'immersion souhaitée, d'obtenir la valeur du volume de la chambre à air, et donc son dimensionnement ainsi que celui des pièces qui la contiennent.This formula allows, for a given construction, to obtain the maximum value of the immersion, and for a maximum value desired immersion, to obtain the volume value of the chamber to air, and therefore its sizing as well as that of the parts which contain.

Ainsi par exemple un transducteur devant être immergé à une profondeur de 30 m devra avoir une chambre à air dont le volume est sensiblement égal à 3 fois le volume d'air dans le reste du transducteur. On remarque ainsi l'intérêt du noyau 118 qui permet de minimiser le volume interne du transducteur, et donc d'augmenter la profondeur d'immersion toutes choses étant égales par ailleurs.So for example a transducer to be immersed at a depth of 30 m must have an air chamber whose volume is substantially equal to 3 times the volume of air in the rest of the transducer. One thus notices the interest of the core 118 which makes it possible to minimize the internal volume of the transducer, and therefore increase the depth immersion all other things being equal.

Claims (4)

Transducteur électrodynamique pour acoustique sous-marine, du type comprenant un corps (101-103) muni de pièces polaires (104,105) définissant un entrefer (107), un équipage mobile muni d'un dôme (109) prolongé par un cylindre supportant un bobinage (120) coulissant dans cet entrefer, et une membrane flexible (115) assurant l'étanchéité entre l'équipage mobile et le corps, caractérisé en ce qu'il comprend en outre un pavillon (110) surmontant ledit dôme (109) et coulissant dans ledit corps en formant avec celui-ci un ajutage dont la valeur du jeu (111) 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.Electrodynamic transducer for underwater acoustics, of the type comprising a body (101-103) provided with pole pieces (104.105) defining an air gap (107), a mobile assembly provided with a dome (109) extended by a cylinder supporting a winding (120) sliding in this air gap, and a flexible membrane (115) ensuring the seal between the moving part and the body, characterized in that it further comprises a pavilion (110) surmounting said dome (109) and sliding in said body, forming with it a nozzle, the clearance value (111) is set so as to protect said clearance shock wave membrane from external explosions to the transducer by laminating these shock waves in said nozzle. Transducteur selon la revendication 1, caractérisé en ce que l'équipage mobile comporte en outre un ensemble de nervures radiales (116) fixées d'un côté sur la paroi intérieure de cet équipage mobile et réunies de l'autre côté en étoile pour augmenter la raideur de cet équipage mobile et sa résistance aux dites onde de choc.Transducer according to claim 1, characterized in that that the moving assembly further comprises a set of ribs radial (116) fixed on one side to the interior wall of this crew mobile and joined on the other side in a star to increase the stiffness of this mobile equipment and its resistance to said shock waves. Transducteur selon la revendication 2, caractérisé en ce qu'il comporte en outre un ressort (119) fixé sur sa périphérie à la partie inférieure du corps (101) et relié en son centre au centre de l'étoile formée par la réunion des dites nervures radiales (116); ce ressort permettant de centrer l'équipage mobile suivant l'axe vertical.Transducer according to claim 2, characterized in that that it further comprises a spring (119) fixed on its periphery to the part lower body (101) and connected in its center to the center of the star formed by the union of said radial ribs (116); this spring allowing the moving equipment to be centered along the vertical axis. Transducteur selon l'une quelconque des revendications 1 à 3, caractérisé en ce qu'il comprend en outre une cavité périphérique (123) ménagée dans le corps et reliée au milieu extérieur par au moins une perforation (124) et une chambre à air torique et élastique (121) contenue dans cette cavité périphérique reliée à la cavité inférieure définie par le corps et l'équipage mobile pour compenser les effets de la pression hydrostatique due à l'immersion; la différence de hauteur entre le pavillon (110) et cette chambre à air permettant de maintenir l'équipage mobile dans une position neutre.A transducer according to any one of claims 1 to 3, characterized in that it further comprises a peripheral cavity (123) formed in the body and connected to the external environment by at least a perforation (124) and a toric and elastic air chamber (121) contained in this peripheral cavity connected to the lower cavity defined by the body and the moving crew to compensate for the effects of the hydrostatic pressure due to immersion; the height difference between the pavilion (110) and this air chamber making it possible to maintain the moving part in a neutral position.
EP98401205A 1997-05-27 1998-05-19 Electrodynamic transducer for underwater acoustics Expired - Lifetime EP0881001B1 (en)

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FR9706457A FR2764160B1 (en) 1997-05-27 1997-05-27 ELECTRODYNAMIC TRANSDUCER FOR UNDERWATER ACOUSTICS
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US6046962A (en) 2000-04-04
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FR2764160A1 (en) 1998-12-04
DE69825361D1 (en) 2004-09-09
DE69825361T2 (en) 2005-08-11

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