EP0473480B1 - Electroacoustic transducer for use under water and comprising a system for automatically compensating the hydrostatic pressure - Google Patents

Electroacoustic transducer for use under water and comprising a system for automatically compensating the hydrostatic pressure Download PDF

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Publication number
EP0473480B1
EP0473480B1 EP19910402172 EP91402172A EP0473480B1 EP 0473480 B1 EP0473480 B1 EP 0473480B1 EP 19910402172 EP19910402172 EP 19910402172 EP 91402172 A EP91402172 A EP 91402172A EP 0473480 B1 EP0473480 B1 EP 0473480B1
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Prior art keywords
casing
transducer
counterweight
gas cushion
gas
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EP19910402172
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German (de)
French (fr)
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EP0473480A1 (en
Inventor
Noel Begnis
Gilbert Oddoart
Henri Ferrazza
Eric Sernit
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Thales SA
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Thomson CSF SA
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0611—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile
    • B06B1/0618—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile of piezo- and non-piezoelectric elements, e.g. 'Tonpilz'

Definitions

  • the present invention relates to electroacoustic transducers, in particular of the "Tonpilz" type, intended to be immersed in water to receive acoustic signals and which comprise a pneumatic compensation system for the immersion pressure intended to maintain constant with the pressure their electroacoustic characteristics.
  • These transducers are more particularly used in underwater acoustic tracking devices known as sonars.
  • This transducer comprises , according to the characteristics of the "Tonpilz" system, a pillar 101 formed of a set of piezoelectric ceramic discs. This pillar excites at one end a pavilion-transmitter 102 by leaning at its other end on a countermass 103. A threaded rod 104 connects the pavilion to the countermass and makes it possible to exert a prestress on the pillar 101.
  • a casing 105 encloses these parts while leaving the front and side faces of the roof in contact with the ambient environment, water when it is immersed.
  • the end of the casing situated opposite the rear face of the roof is parallel to the latter in order to leave an air gap 106.
  • Connecting pieces 107, 108 and 109 make it possible to maintain the casing relative to the other members of the transducer.
  • These parts have dynamic and static guiding functions, impact resistance, and sealing against the outside environment. Therefore, they must present minimum mechanical and acoustic stiffness so as not to disturb the operation of the Tonpilz.
  • one of the known technological solutions consists in choosing, as the material constituting these parts, materials with a low Young's modulus which a priori has good sealing characteristics, such as rubber or various polymers. They are generally in the form of a ring similar to an O-ring.
  • the thickness of the air gap 106 greatly influences the characteristics of the transducer, and it is essential to keep it as constant as possible.
  • the so-called "bellows" solution described in the patent cited above consists in using a chamber 110 external to the casing, obtained for example by fixing on it an elastic membrane 111. This chamber feeds through the orifices 114, 115 and 116 drilled in the casing the air gap 106 and the volumes 112 and 113 delimited by the connecting pieces 108 and 109.
  • the chamber is initially inflated with a gas such as air under a pressure equal to that of maximum immersion. As the transducer sinks into the water, the volume of the chamber decreases and those of the blade and the spaces 112 and 113 remain substantially constant.
  • This known device has a number of drawbacks.
  • the volume of air to be compensated constituted by the blade 106 and the spaces 112 and 113 is relatively large.
  • the compensation chamber must contain a large quantity of gas at an initial pressure which corresponds to the hydraulic pressure at working immersion. This pressure thus reaches 30.105 Pa (30 bars) for 300 m, which is considerable.
  • There is thus a need for a compensation chamber which has a large size compared to the properly active elements of the transducer and which requires a thick membrane to withstand the pressure, without however being certain that this membrane will not have a certain porosity requiring periodic verification of the inflation pressure.
  • the connecting pieces which must be made with a sufficiently flexible material, constitute weak points in the assembly because such a material has poor qualities in dynamic operation and in fatigue.
  • the strong hydrostatic pressures exerted on these parts further accentuate the mediocrity of these materials.
  • the connecting pieces therefore only eventually exhibit a low barrier to the external environment, which can lead to a breakdown following the introduction of water into volumes 106, 112 and 113. The contact of this water with the pillar 101 ceramics then proved to be catastrophic.
  • the invention proposes an electroacoustic transducer with pneumatic compensation for large immersion, of the type comprising a transmitting horn connected to a countermass by a ceramic pillar, and a casing enveloping these members to delimit between the rear face of the horn and it -even a gas blade of substantially constant thickness, a compensation chamber located outside the housing and delimited by an elastic membrane communicating at least with the gas blade, mainly characterized in that it comprises between the housing and at least the ceramic pillar a volume of uncompensated gas which is not connected to the compensation chamber.
  • the volumes to be compensated have been limited to the gas blade 106 and the blade 213, the latter corresponding to the volume 113 but limited to the rear face of the countermass 103 by a connecting piece 209 located at the rear end of the side face of this countermass.
  • the connecting pieces 207, 208 and 209 correspond to the pieces 107, 108 and 109 in FIG. 1.
  • the connecting piece 208 has been moved forward as much as possible to limit the dimensions of the gas blade 106 to what is strictly necessary .
  • This blade 106 is then supplied by the orifice 114, and the blade 213 by a pneumatic connection member, which is in the example shown a pipe 216 connecting the volume 110 to the blade 213. It would be possible to use two tanks separate gases to each supply one of the gas blades, respectively.
  • the space 212 can simply contain air at atmospheric pressure trapped during assembly, or possibly a gas with better characteristics dielectric than air and improving the breakdown resistance of the ceramic pillar.
  • the housing 105 can withstand the hydrostatic pressure corresponding to the maximum immersion depth.
  • the connecting parts 208 and 209 must undergo this pressure without leaking and without moving.
  • FIG. 3 represents substantially the same view as FIG. 2 with the same members, except, however, the connecting pieces which are very schematically represented by members 307, 308 and 309.
  • An enlarged view of the end of the casing and of the pavilion carrying the gas slide 106 and parts 307 and 308 is shown in Figure 4.
  • This structure is formed of '' a metal blade 321 having the general shape of a torus cut to keep only an outer crown for parts 307 and 309 and an inner crown for part 308.
  • This part is obtained for example from a metal blade elongated rolled up to form a cylinder and then shaped by any known method. An appropriate heat treatment then makes it possible to remove the stresses due to shaping and to restore the necessary elasticity to it.
  • the connecting piece 508 which has the shape of a diaphragm comprising a part 521 in slightly circular conical crown shape to be parallel to the rear face of the pavilion.
  • This crown is extended by a cylindrical part of low height, which is fixed on the edges of the internal hole of the crown 521.
  • This diaphragm is relatively, thick which allows it by working in bending to support the force not compensated for. back of the countermass and keep the transducer assembly centered in the housing 105.
  • a thinner diaphragm can be used while maintaining a smaller gas gap 213 obtained by a connecting piece 309 of more restricted dimensions, which therefore connects the casing to the countermass closer to the axis of the transducer.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Description

La présente invention se rapporte aux transducteurs électroacoustiques, notamment du type "Tonpilz", destinés à être immergés dans l'eau pour recevoir des signaux acoustiques et qui comportent un système de compensation pneumatique de la pression d'immersion destiné à maintenir constantes avec la pression leurs caractéristiques électroacoustiques. Ces transducteurs sont plus particulièrement utilisés dans les appareils de repérage acoustique sous-marins connus sous le nom de sonars.The present invention relates to electroacoustic transducers, in particular of the "Tonpilz" type, intended to be immersed in water to receive acoustic signals and which comprise a pneumatic compensation system for the immersion pressure intended to maintain constant with the pressure their electroacoustic characteristics. These transducers are more particularly used in underwater acoustic tracking devices known as sonars.

Il est connu du brevet français n° 80 26647 (FR-A- 2 496 379) déposé le 16/12/80 par la demanderesse de réaliser un tel transducteur d'une manière semblable à celle représentée sur la figure 1. Ce transducteur comprend, selon les caractéristiques du système "Tonpilz", un pilier 101 formé d'un ensemble de disques de céramique piézoélectrique. Ce pilier excite à une extrémité un pavillon-émetteur 102 en s'appuyant par son autre extrémité sur une contremasse 103. Une tige filetée 104 relie le pavillon à la contremasse et permet d'exercer une précontrainte sur le pilier 101.It is known from French patent n ° 80 26647 (FR-A- 2 496 379) filed on 12/16/80 by the applicant to produce such a transducer in a manner similar to that shown in FIG. 1. This transducer comprises , according to the characteristics of the "Tonpilz" system, a pillar 101 formed of a set of piezoelectric ceramic discs. This pillar excites at one end a pavilion-transmitter 102 by leaning at its other end on a countermass 103. A threaded rod 104 connects the pavilion to the countermass and makes it possible to exert a prestress on the pillar 101.

Un carter 105 enferme ces pièces tout en laissant les faces avant et latérale du pavillon au contact du milieu ambiant, l'eau quand il est immergé. L'extrémité du carter située en regard de la face arrière du pavillon est parallèle à celle-ci pour laisser subsister une lame d'air 106.A casing 105 encloses these parts while leaving the front and side faces of the roof in contact with the ambient environment, water when it is immersed. The end of the casing situated opposite the rear face of the roof is parallel to the latter in order to leave an air gap 106.

Des pièces de liaison 107, 108 et 109 permettent de maintenir le carter par rapport aux autres organes du transducteur. Ces pièces ont des fonctions de guidage dynamique et statique, de maintien aux chocs, et d'étanchéïté envers le milieu extérieur. De ce fait, elles doivent présenter des raideurs mécaniques et acoustiques minimales de façon à ne pas perturber le fonctionnement du Tonpilz. Afin de concilier ces différentes contraintes une des solutions technologiques connues consiste à choisir comme matériau constituant ces pièces des matériaux à faible module de Young qui présente à priori de bonnes caractéristiques en étanchéité, comme le caoutchouc ou divers polymères. Elles se présentent généralement sous la forme d'un anneau semblable à un joint torique.Connecting pieces 107, 108 and 109 make it possible to maintain the casing relative to the other members of the transducer. These parts have dynamic and static guiding functions, impact resistance, and sealing against the outside environment. Therefore, they must present minimum mechanical and acoustic stiffness so as not to disturb the operation of the Tonpilz. In order to reconcile these different constraints, one of the known technological solutions consists in choosing, as the material constituting these parts, materials with a low Young's modulus which a priori has good sealing characteristics, such as rubber or various polymers. They are generally in the form of a ring similar to an O-ring.

L'épaisseur de la lame d'air 106 influe beaucoup sur les caractéristiques du transducteur, et il est essentiel de la maintenir aussi constante que possible. La solution dite "soufflet" décrite dans le brevet cité plus haut consiste à utiliser une chambre 110 extérieure au carter, obtenue par exemple en fixant sur celui-ci une membrane élastique 111. Cette chambre alimente par les orifices 114, 115 et 116 percés dans le carter la lame d'air 106 et les volumes 112 et 113 délimités par les pièces de liaison 108 et 109. La chambre est gonflée au départ avec un gaz tel que l'air sous une pression égale à celle de l'immersion maximale. Au fur et à mesure que le transducteur s'enfonce dans l'eau, le volume de la chambre diminue et ceux de la lame et des espaces 112 et 113 reste sensiblement constant.The thickness of the air gap 106 greatly influences the characteristics of the transducer, and it is essential to keep it as constant as possible. The so-called "bellows" solution described in the patent cited above consists in using a chamber 110 external to the casing, obtained for example by fixing on it an elastic membrane 111. This chamber feeds through the orifices 114, 115 and 116 drilled in the casing the air gap 106 and the volumes 112 and 113 delimited by the connecting pieces 108 and 109. The chamber is initially inflated with a gas such as air under a pressure equal to that of maximum immersion. As the transducer sinks into the water, the volume of the chamber decreases and those of the blade and the spaces 112 and 113 remain substantially constant.

Ce dispositif connu présente un certain nombre d'inconvénients.This known device has a number of drawbacks.

Tout d'abord le volume d'air à compenser, constitué par la lame 106 et les espaces 112 et 113 est relativement important. Pour alimenter ce volume la chambre de compensation doit contenir une quantité de gaz importante sous une pression initiale qui correspond à la pression hydraulique à l'immersion de travail. Cette pression atteint ainsi 30.10⁵ Pa (30 bars) pour 300 m, ce qui considérable. On a ainsi besoin d'une chambre de compensation qui présente une taille importante par rapport aux éléments proprement actifs du transducteur et qui nécessite une membrane épaisse pour résister à la pression, sans toutefois être certain que cette membrane ne présentera pas une certaine porosité nécessitant une vérification périodique de la pression de gonflage.First of all, the volume of air to be compensated, constituted by the blade 106 and the spaces 112 and 113 is relatively large. To supply this volume, the compensation chamber must contain a large quantity of gas at an initial pressure which corresponds to the hydraulic pressure at working immersion. This pressure thus reaches 30.10⁵ Pa (30 bars) for 300 m, which is considerable. There is thus a need for a compensation chamber which has a large size compared to the properly active elements of the transducer and which requires a thick membrane to withstand the pressure, without however being certain that this membrane will not have a certain porosity requiring periodic verification of the inflation pressure.

D'autre part les pièces de liaison, qui doivent être réalisées avec un matériau suffisamment souple, constituent des points faibles de l'ensemble parce qu'un tel matériau présente des qualités médiocres en fonctionnement dynamique et en fatigue. Les fortes pressions hydrostatiques exercées sur ces pièces accentuent encore la médiocrité de ces matériaux. Les pièces de liaison ne présentent donc à terme qu'une faible barrière d'étanchéïté au milieu extérieur, ce qui peut entraîner une panne suite à l'introduction d'eau dans les volumes 106, 112 et 113. Le contact de cette eau avec les céramiques du pilier 101 se révèle alors catastrophique.On the other hand, the connecting pieces, which must be made with a sufficiently flexible material, constitute weak points in the assembly because such a material has poor qualities in dynamic operation and in fatigue. The strong hydrostatic pressures exerted on these parts further accentuate the mediocrity of these materials. The connecting pieces therefore only eventually exhibit a low barrier to the external environment, which can lead to a breakdown following the introduction of water into volumes 106, 112 and 113. The contact of this water with the pillar 101 ceramics then proved to be catastrophic.

Pour pallier ces inconvénients l'invention propose un transducteur électroacoustique à compensation pneumatique pour grande immersion, du type comprenant un pavillon émetteur relié à une contremasse par un pilier de céramique, et un carter enveloppant ces organes pour délimiter entre la face arrière du pavillon et lui-même une lame de gaz d'épaisseur sensiblement constante, une chambre de compensation située à l'extérieur du carter et délimitée par une membrane élastique communiquant au moins avec la lame de gaz, principalement caractérisé en ce qu'il comporte entre le carter et au moins le pilier de céramique un volume de gaz non compensé qui n'est pas relié à la chambre de compensation.To overcome these drawbacks, the invention proposes an electroacoustic transducer with pneumatic compensation for large immersion, of the type comprising a transmitting horn connected to a countermass by a ceramic pillar, and a casing enveloping these members to delimit between the rear face of the horn and it -even a gas blade of substantially constant thickness, a compensation chamber located outside the housing and delimited by an elastic membrane communicating at least with the gas blade, mainly characterized in that it comprises between the housing and at least the ceramic pillar a volume of uncompensated gas which is not connected to the compensation chamber.

Des modes particuliers de réalisation de l'invention sont indiqués dans les revendications dépendantesParticular embodiments of the invention are indicated in the dependent claims

D'autres particularités et avantages de l'invention apparaîtront clairement dans la description suivante faite en regard des figures annexées qui représentent :

  • la figure 1, une coupe d'un transducteur connu ;
  • la figure 2, une coupe d'un transducteur selon l'invention ;
  • les figures 3 et 5, des coupes de variantes de la figure 2 ;
  • les figures 4 et 6, des coupes des pièces de liaison des figures 3 et 5.
Other features and advantages of the invention will appear clearly in the following description given with reference to the appended figures which represent:
  • Figure 1, a section of a known transducer;
  • Figure 2, a section of a transducer according to the invention;
  • Figures 3 and 5, sections of variants of Figure 2;
  • Figures 4 and 6, sections of the connecting pieces of Figures 3 and 5.

En ce qui concerne l'action sur l'épaisseur de la lame 106, on peut constater que seules les résultantes des forces axiales selon l'axe z contribuent à l'équilibre statique du tranducteur dont le pavillon à tendance à reculer par rapport à la contremasse sous l'effet de la pression du milieu extérieur sur la face externe avant du pavillon. Les résultantes radiales selon r de la pression ne participent pas à l'équilibre du transducteur et sont sans influence sur l'épaisseur de cette lame de gaz 106. Le volume 112 est donc inutile pour le type de compensation recherché, ainsi que la partie du volume 113 qui n'est pas située sur la face arrière de la contremasse 103.With regard to the action on the thickness of the blade 106, it can be seen that only the results of the axial forces along the z axis contribute to the static equilibrium of the transducer whose pavilion tends to move back with respect to the counterweight under the effect of the pressure of the external environment on the external front face of the roof. The radial resultants according to r of the pressure do not participate in the equilibrium of the transducer and have no influence on the thickness of this gas plate 106. The volume 112 is therefore unnecessary for the type of compensation sought, as well as the part of the volume 113 which is not located on the rear face of the countermass 103.

Dans un premier mode de réalisation de l'invention, représenté sur la figure 2, on a limité les volumes à compenser à la lame de gaz 106 et la lame 213, celle-ci correspondant au volume 113 mais limité à la face arrière de la contremasse 103 par une pièce de liaison 209 située à l'extrémité arrière de la face latérale de cette contremasse. Les pieces de liaison 207, 208 et 209 correspondent à les pieces 107, 108 et 109 de la figure 1. La pièce de liaison 208 a été déplacée vers l'avant au maximum pour limiter les dimensions de la lame de gaz 106 au strict nécessaire. Cette lame 106 est alors alimentée par l'orifice 114, et la lame 213 par un organe de liaison pneumatique, qui est dans l'exemple représenté un tuyau 216 reliant le volume 110 à la lame 213. Il serait possible d'utiliser deux réservoirs de gaz distincts pour alimenter chacun respectivement l'une des lames de gaz.In a first embodiment of the invention, shown in FIG. 2, the volumes to be compensated have been limited to the gas blade 106 and the blade 213, the latter corresponding to the volume 113 but limited to the rear face of the countermass 103 by a connecting piece 209 located at the rear end of the side face of this countermass. The connecting pieces 207, 208 and 209 correspond to the pieces 107, 108 and 109 in FIG. 1. The connecting piece 208 has been moved forward as much as possible to limit the dimensions of the gas blade 106 to what is strictly necessary . This blade 106 is then supplied by the orifice 114, and the blade 213 by a pneumatic connection member, which is in the example shown a pipe 216 connecting the volume 110 to the blade 213. It would be possible to use two tanks separate gases to each supply one of the gas blades, respectively.

Pour une même profondeur limite d'immersion, le volume de gaz à emmagasiner et les contraintes dues à la pression de gonflage sont alors nettement plus faibles que dans la solution de la figure 1, ce qui augmente la fiabilité du dispositif. Inversement pour un même volume et une même pression de gaz, avec donc une fiabilité équivalente, on peut obtenir une profondeur d'immersion, maximum plus importante.For the same immersion limit depth, the volume of gas to be stored and the stresses due to the inflation pressure are then significantly lower than in the solution of FIG. 1, which increases the reliability of the device. Conversely, for the same volume and the same gas pressure, with therefore equivalent reliability, it is possible to obtain a greater maximum immersion depth.

L'espace 212 quant à lui peut simplement contenir l'air à la pression atmosphérique enfermé lors du montage, ou éventuellement un gaz ayant de meilleures caractéristiques diélectriques que l'air et permettant d'améliorer la tenue au claquage du pilier de céramique.The space 212 can simply contain air at atmospheric pressure trapped during assembly, or possibly a gas with better characteristics dielectric than air and improving the breakdown resistance of the ceramic pillar.

Par contre il est nécessaire que le carter 105 puisse résister à la pression hydrostatique correspondant à la profondeur d'immersion maximale. De même les pièces de liaison 208 et 209 doivent subir cette pression sans fuir et sans se déplacer.By cons it is necessary that the housing 105 can withstand the hydrostatic pressure corresponding to the maximum immersion depth. Similarly, the connecting parts 208 and 209 must undergo this pressure without leaking and without moving.

Bien qu'on puisse obtenir un tel résultat par différents procédés, par exemple en collant ces pièces de liaison sur le carter et le transducteur, ou en ménageant des gorges suffisamment profondes sur ces pièces pour les maintenir, on a imaginé selon l'invention de les réaliser de la manière représentée sur les figures 3 et 4.Although such a result can be obtained by various methods, for example by bonding these connecting parts to the casing and the transducer, or by providing grooves deep enough on these parts to hold them, it has been imagined according to the invention to make them as shown in Figures 3 and 4.

La figure 3 représente substantiellement la même vue que la figure 2 avec les mêmes organes, sauf toutefois les pièces de liaison qui sont représentées de manière très schématique par les organes 307, 308 et 309. Une vue aggrandie de l'extrémité du carter et du pavillon portant la lame de gaz 106 et les pièces 307 et 308 est représentée en figure 4. Sur cette figure on constate que les deux pièces 307 et 308 on la même structure, qui est également celle de la pièce 309. Cette structure est formée d'une lame métallique 321 ayant la forme générale d'un tore découpé pour ne garder qu'une couronne extérieure pour les pièces 307 et 309 et une couronne intérieure pour la pièce 308. Cette pièce est obtenue par exemple à partir d'une lame métallique allongée enroulée pour former un cylindre et mise ensuite en forme par tout procédé connu. Un traitement thermique approprié permet ensuite de supprimer les contraintes dues à la mise en forme et de lui restituer l'élasticité nécessaire.FIG. 3 represents substantially the same view as FIG. 2 with the same members, except, however, the connecting pieces which are very schematically represented by members 307, 308 and 309. An enlarged view of the end of the casing and of the pavilion carrying the gas slide 106 and parts 307 and 308 is shown in Figure 4. In this figure we see that the two parts 307 and 308 have the same structure, which is also that of part 309. This structure is formed of '' a metal blade 321 having the general shape of a torus cut to keep only an outer crown for parts 307 and 309 and an inner crown for part 308. This part is obtained for example from a metal blade elongated rolled up to form a cylinder and then shaped by any known method. An appropriate heat treatment then makes it possible to remove the stresses due to shaping and to restore the necessary elasticity to it.

On met ensuite ces pièces en position et on les fixe sur le pavillon et sur le carter respectivement par des soudures 322 et 323 qui réalisent l'étanchéïté souhaitée.These parts are then placed in position and fixed on the roof and on the casing respectively by welds 322 and 323 which provide the desired seal.

De telles pièces de liaison ne provoquent pas de pertes mécaniques et travaillent très bien en fatigue. La forme ainsi décrite permet d'obtenir une très faible raideur axiale.Such connecting pieces do not cause mechanical losses and work very well in fatigue. The shape thus described makes it possible to obtain a very low axial stiffness.

Toutefois dans une telle structure on constate que lorsque le transducteur est soumis à la pression hydrostatique le pilier de céramique central subi une compression axiale proportionnelle à cette pression. Celle-ci vient alors s'ajouter à la précontrainte statique et aux contraintes dynamiques dues à l'émission sonore. La somme algébrique de ces trois composantes peut très bien dépasser la limite de compression des céramiques à partir de laquelle on voit apparaître des variations importantes des caractéristiques de fonctionnement du transducteur. Pour limiter cette compression supplémentaire, on a imaginé, selon l'invention, de supprimer la pièce de liaison 309 délimitant la lame d'air 213 située sur l'arrière de la contremasse, comme représenté sur la figure 5. Dans ces conditions le transducteur n'est plus en équilibre et il est nécessaire de faire supporter l'effort non compensé d'une autre manière.However, in such a structure, it can be seen that when the transducer is subjected to hydrostatic pressure, the central ceramic pillar undergoes axial compression proportional to this pressure. This is then added to the static prestress and the dynamic stresses due to the sound emission. The algebraic sum of these three components may very well exceed the compression limit of ceramics from which we see significant variations in the operating characteristics of the transducer appear. To limit this additional compression, it has been imagined, according to the invention, to remove the connecting piece 309 delimiting the air space 213 situated on the rear of the countermass, as shown in FIG. 5. Under these conditions the transducer is no longer in balance and it is necessary to support the uncompensated effort in another way.

Pour cela, on a imaginé, selon l'invention, de modifier la pièce de liaison 308 de manière à lui donner la forme représentée schématiquement sur la figure 5, et de manière agrandie sur la figure 6.For this, it has been imagined, according to the invention, to modify the connecting piece 308 so as to give it the shape shown diagrammatically in FIG. 5, and in an enlarged manner in FIG. 6.

Comme on le voit sur ces figures, la partie inférieure du boîtier 105 qui se prolonge pour être parallèle à la face arrière du pavillon 102 est supprimée et remplacée par la pièce de liaison 508 qui a la forme d'un diaphragme comportant une partie 521 en forme de couronne circulaire légèrement conique pour être parallèle à la face arrière du pavillon. Cette couronne est prolongée par une partie cylindrique de faible hauteur, qui est fixée sur les bords du trou interne de la couronne 521. Ce diaphragme est relativement, épais ce qui lui permet en travaillant en flexion de supporter l'effort non compensé à l'arrière de la contremasse et de maintenir centré dans le carter 105 l'ensemble du transducteur. Dans ce cas on augmente la raideur axiale des pièces de liaison, ce qui modifie la fréquence de résonance du tranducteur dans son carter. Toutes choses égales par ailleurs ce transducteur résone alors sur une fréquence plus élevée que celui de la figure 1. La prise en compte de cet effet pour obtenir la fréquence souhaitée ne présente aucune difficulté de dimensionnement.As can be seen in these figures, the lower part of the housing 105 which extends to be parallel to the rear face of the roof 102 is eliminated and replaced by the connecting piece 508 which has the shape of a diaphragm comprising a part 521 in slightly circular conical crown shape to be parallel to the rear face of the pavilion. This crown is extended by a cylindrical part of low height, which is fixed on the edges of the internal hole of the crown 521. This diaphragm is relatively, thick which allows it by working in bending to support the force not compensated for. back of the countermass and keep the transducer assembly centered in the housing 105. In this case we increases the axial stiffness of the connecting parts, which changes the resonant frequency of the driver in its housing. All other things being equal, this transducer then resonates on a higher frequency than that of FIG. 1. Taking this effect into account to obtain the desired frequency presents no dimensioning difficulty.

Le cas échéant, si l'épaisseur du diaphragme 508 nécessaire pour supprimer totalement la lame d'air 213 est trop importante pour obtenir des résultats corrects, on peut utiliser un diaphragme de plus faible épaisseur en maintenant une lame de gaz 213 plus réduite obtenue par une pièce de liaison 309 de dimensions plus restreintes, qui relie donc le carter à la contremasse plus près de l'axe du transducteur.If necessary, if the thickness of the diaphragm 508 necessary to completely remove the air gap 213 is too great to obtain correct results, a thinner diaphragm can be used while maintaining a smaller gas gap 213 obtained by a connecting piece 309 of more restricted dimensions, which therefore connects the casing to the countermass closer to the axis of the transducer.

Claims (5)

  1. Electroacoustic transducer with pneumatic compensation for deep submersion, of the type comprising a transmitter horn (102) connected to a counterweight (103) by a ceramic strut (101), and a casing (105) enveloping these members so as to delimit between the rear face of the horn and itself a gas cushion (106) of substantially constant thickness, a compensation chamber (110) situated outside the casing and delimited by an elastic membrane (111) communicating at least with the gas cushion, characterized in that it includes, between the casing and at least the ceramic strut (101), an uncompensated gas volume (212) which is not connected to the compensation chamber (110).
  2. Transducer according to Claim 1, characterized in that it includes, between the rear of the counterweight (103) and the casing (105), a compensated volume which is connected to the compensation chamber (110).
  3. Transducer according to Claim 2, characterized in that it comprises two compensation volumes connected respectively to the air cushion (106) and to the compensated volume situated behind the counterweight (213).
  4. Transducer according to any one of Claims 1 to 3, characterized in that it comprises linking parts making it possible to delimit at least the gas cushion (106), these parts being formed by a curved metal sheet having a concavity turned towards the inside of the gas cushion (106) having the shape of a hollowed-out torus and connected in a sealed manner on one side to the casing and on the other side to the transmitter horn (102) and possibly the counterweight (103).
  5. Transducer according to Claim 1, characterized in that only the gas cushion (106) is compensated and that it comprises a diaphragm-shaped linking part having a ring-shaped portion (521) parallel to the rear face of the horn (102), this portion being connected to this rear face by a cylindrical portion (522) fixed to the inner edge of the central hole of the ring, this diaphragm having a thickness sufficient to centre the transducer in the casing and to take up the uncompensated loads at the rear of the counterweight.
EP19910402172 1990-08-10 1991-08-02 Electroacoustic transducer for use under water and comprising a system for automatically compensating the hydrostatic pressure Expired - Lifetime EP0473480B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9010249 1990-08-10
FR9010249A FR2665814B1 (en) 1990-08-10 1990-08-10 ELECTROACOUSTIC TRANSDUCER INTENDED TO BE UNDERWATER AND INCLUDING A SYSTEM FOR AUTOMATIC COMPENSATING FOR IMMERSION PRESSURE.

Publications (2)

Publication Number Publication Date
EP0473480A1 EP0473480A1 (en) 1992-03-04
EP0473480B1 true EP0473480B1 (en) 1994-04-13

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Family Applications (1)

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EP19910402172 Expired - Lifetime EP0473480B1 (en) 1990-08-10 1991-08-02 Electroacoustic transducer for use under water and comprising a system for automatically compensating the hydrostatic pressure

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EP (1) EP0473480B1 (en)
FR (1) FR2665814B1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2697711B1 (en) * 1992-11-05 1994-12-30 France Etat Armement Method and transducer for emitting low frequency acoustic waves in a liquid in unlimited immersion.
FR2713430B1 (en) * 1993-12-03 1996-03-08 France Etat Armement Method for emitting very low frequency acoustic waves at high power, and corresponding transducers.
FR2720589B1 (en) * 1994-05-27 1996-07-05 France Etat Armement Method and transducer for emitting wideband and low frequency acoustic waves in unlimited immersion depth.

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3539980A (en) * 1968-11-29 1970-11-10 Dynamics Corp America Underwater electroacoustic transducer which resists intense pressure
FR2290813A1 (en) * 1974-11-08 1976-06-04 Thomson Csf Pressure resistant electro-acoustic transducer - has transmitter or receiver device resisting hydrostatic pressure using special fluid
FR2496379A1 (en) * 1980-12-16 1982-06-18 Tech Radioelect Electro Fs Underwater electroacoustic transducer - has piezoelectric stack and surrounding envelope enclosing protective gas cushion

Also Published As

Publication number Publication date
EP0473480A1 (en) 1992-03-04
FR2665814A1 (en) 1992-02-14
FR2665814B1 (en) 1993-06-11

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