EP0583805A1 - Flextensional transducer - Google Patents

Flextensional transducer Download PDF

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Publication number
EP0583805A1
EP0583805A1 EP19930117557 EP93117557A EP0583805A1 EP 0583805 A1 EP0583805 A1 EP 0583805A1 EP 19930117557 EP19930117557 EP 19930117557 EP 93117557 A EP93117557 A EP 93117557A EP 0583805 A1 EP0583805 A1 EP 0583805A1
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EP
European Patent Office
Prior art keywords
shell
transducer
stacks
cavity
reservoir
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.)
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Application number
EP19930117557
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German (de)
French (fr)
Inventor
Bernard Tocquet
Michel Letiche
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Thales SA
Original Assignee
Thomson CSF SA
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Publication of EP0583805A1 publication Critical patent/EP0583805A1/en
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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
    • G10K9/00Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers
    • G10K9/12Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated
    • G10K9/121Flextensional transducers
    • 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
    • B06B1/06Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607Methods 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
    • B06B1/0611Methods 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
    • B06B1/0618Methods 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 a flexural transducer. It applies to the emission or reception of acoustic waves in liquids.
  • Known flextensor transducers are generally composed of a flexible, watertight shell with a cylindrical side wall of elliptical cross section, vibrated by one or more pillars or bars of piezoelectric ceramic cells. Each pillar is kept in compression between the opposite parts furthest from the side wall. In emission, an alternating electric field is applied in the longitudinal direction of each pillar and the resulting movement, which takes place along the longitudinal axis of each pillar, is transmitted, amplified, to the surrounding liquid medium, the amplitude of this movement being maximum in the plane generated by the minor axes of the ellipses formed by each cross section.
  • the compression of the piezoelectric cells of each pillar is necessary to avoid breakage of the ceramic when the pillars are stressed in extension.
  • a first prestressing is applied to stacks of piezoelectric cells during the assembly of the stacks inside the shell.
  • the stacks extend, symmetrically on either side of mechanical wedging means centered inside the hull, along the major axis of the elliptical cross section of the hull.
  • This prestressing ensures the maintenance of the stacks in support respectively by a first end on the wedging means and by a second end on the inner part of the shell corresponding to one end of the major axis of the ellipse.
  • the preload is adjusted as a function of the operational depth of immersion of the transducer to compensate for the hydrostatic forces exerted on the outside of the hull and guarantee the constant maintenance of the stacks for the proper functioning of the transducer.
  • the mechanical wedging means comprise a frustoconical part making it possible, from its vertical displacement, to transmit the necessary pressure force on the stacks.
  • the movement of the frustoconical part is ensured by tightening or loosening a screw fixed on its upper part.
  • the tightening determines the amplitude of the prestressing force to be applied to the stacks.
  • the screw can be replaced by a hydraulic ram and the pressure exerted on the ram is determined from a pressure sensor.
  • the sensor measures the amplitude of the hydrostatic pressure applied to the shell of the transducer and makes it possible to adjust the pressure exerted on the ram.
  • this embodiment has the drawback that the prestressing exerted on the stacks during immersion is dependent on the hydrostatic forces exerted on the shell and that the use of such a transducer is limited by the mechanical resistance in compression of the piezoelectric cells. This drawback is also observed in the transducer according to patent FR-A-2 361 033. This embodiment also has the drawback that it requires a measurement means such as a sensor for measuring the hydrostatic pressure and a control means using this measurement to control a hydraulic ram.
  • the object of the invention is to overcome the aforementioned drawbacks.
  • the subject of the invention is a flextensor transducer composed of a flexible and waterproof shell with a cylindrical side wall of elliptical cross section comprising at least two stacks of piezoelectric cells aligned on the same longitudinal axis and held in abutment by one of their first end on two opposite parts of the shell by a fluidic device, characterized in that the stacks of piezoelectric cells are maintained respectively around a rod and provided respectively at their ends with two mechanical parts to establish a prestressing force independent of the hydrostatic pressure exerted on the shell of the transducer during its immersion, in that the fluidic device comprises a cavity into which the second ends of the stacks are introduced, filled with a fluid under pressure coming from an external reservoir placed at the same immersion depth as the transducer, to ensure that the first end of each of the stacks remains supported on the shell under the effect of the pressure of the fluid exerted on their second ends and compensate in the cavity for the effect of the hydrostatic pressure exerted on the hull.
  • the main advantage of the invention is that it makes it possible, on the one hand, to make the prestressing exerted on the stacks independent of the hydrostatic pressure exerted on the hull, and in this way, the transducers thus produced can operate at much higher immersions. to the usual immersions, and on the other hand, to use only a means of direct servo-control of the hydrostatic pressure applied to the shell of the transducer to the pressure applied to the stacks of piezoelectric cells.
  • a first embodiment of a flexuring transducer according to the invention is described below with the aid of FIG. 1.
  • This transducer comprises a flexible and watertight shell, with a cylindrical lateral wall of elliptical cross section 1, containing at least two pillars 2 and 3 formed respectively by a stack, around a rod 4 and 5, of a plurality of piezoelectric cells, 6i and 7i, ceramic.
  • the pillars 2 and 3 are provided at their ends with two mechanical parts 8 and 9 respectively 10, 11 to establish the prestressing force of the pillars 2 and 3 independent of the hydrostatic pressure exerted on the shell 1 during its immersion .
  • a fluidic device 12 is disposed between the ends of the two pillars 2 and 3 furthest from the shell 1.
  • This device consists of a cavity 13 filled with oil connected to an external reservoir 14 by a capillary pipe 15.
  • the cavity 13 is produced, for example, by means of a part of revolution forming a housing surrounding the two ends of the pillars 2 and 3.
  • At least two elastomeric seals 16, 17 seal the cavity 13 with the ends of the pillars 2 and 3.
  • the stiffness of the oil film is high at the operating frequency, and provides a high mass in the center of the cavity 13 in a manner identical to the known art.
  • the vibration speed being low since we are at the nodal point, the seals 16, 17 work in good conditions.
  • each pillar 2, 3 can optionally be supported on the shell 1 by means of an appropriate housing in the shell 1.
  • the mounting of a transducer can also be carried out according to a "collective" method, as shown in FIG. 2, by making the fluid housing 12 common to all the pillars 2 i . Under these conditions the housing-pillar assembly which has the shape of a "fishbone” is introduced into the shell 1 in a single operation and their common housing 12 and connected to a single oil tank 14 by the capillary pipe 15.

Abstract

Le transducteur flextenseur selon l'invention permet l'émission et la réception d'ondes acoustiques dans l'eau à de très grandes profondeurs. Il comprend au moins deux piliers (2 et 3) de cellules piézoéllectriques (6i et 7i), placés à l'intérieur d'une coque (1) étanche. Chaque pilier (2 et 3) est maintenu en appui par une première extrémité (8, 10) à la coque (1) et est compressé par la deuxième extrémité à un dispositif fluidique (12) comportant une cavité (13), renfermant un fluide sous pression provenant d'un réservoir (14) extérieur placé à la même profondeur d'immersion que le transducteur, et dans laquelle est introduite la deuxième extrémité (9, 11) de chaque pilier (2, 3). L'étanchéité de la cavité (13) avec les extrémités (9, 11) de chaque empilement (2, 3) est assurée par un joint élastomère (16, 17). La cavité (13) communique par un tuyau capillaire (15) avec le fluide contenu dans un réservoir (14) placé à la même profondeur d'immersion que le transducteur. Application : Sonar <IMAGE>The flextensor transducer according to the invention allows the emission and reception of acoustic waves in water at very great depths. It comprises at least two pillars (2 and 3) of piezoelectric cells (6i and 7i), placed inside a sealed shell (1). Each pillar (2 and 3) is held in abutment by a first end (8, 10) to the shell (1) and is compressed by the second end to a fluidic device (12) comprising a cavity (13), containing a fluid under pressure from an external reservoir (14) placed at the same immersion depth as the transducer, and into which the second end (9, 11) of each pillar (2, 3) is introduced. The sealing of the cavity (13) with the ends (9, 11) of each stack (2, 3) is ensured by an elastomeric seal (16, 17). The cavity (13) communicates by a capillary pipe (15) with the fluid contained in a reservoir (14) placed at the same immersion depth as the transducer. Application: Sonar <IMAGE>

Description

La présente invention concerne un transducteur flextenseur. Elle s'applique à l'émission ou à la réception d'ondes acoustiques dans des liquides.The present invention relates to a flexural transducer. It applies to the emission or reception of acoustic waves in liquids.

Les transducteurs flextenseurs connus sont composés généralement par une coque flexible, étanche, à paroi latérale cylindrique de section droite elliptique, mise en vibration par un ou plusieurs piliers ou barreaux de cellules piézoélectriques en céramique. Chaque pilier est maintenu en compression entre les parties opposées les plus éloignées de la paroi latérale. En émission, un champ électrique alternatif est appliqué dans la direction longitudinale de chaque pilier et le mouvement résultant, qui a lieu suivant l'axe longitudinal de chaque pilier, est retransmis, amplifié, au milieu liquide environnant, l'amplitude de ce mouvement étant maximale dans le plan engendré par les petits axes des ellipses formées par chaque section droite.Known flextensor transducers are generally composed of a flexible, watertight shell with a cylindrical side wall of elliptical cross section, vibrated by one or more pillars or bars of piezoelectric ceramic cells. Each pillar is kept in compression between the opposite parts furthest from the side wall. In emission, an alternating electric field is applied in the longitudinal direction of each pillar and the resulting movement, which takes place along the longitudinal axis of each pillar, is transmitted, amplified, to the surrounding liquid medium, the amplitude of this movement being maximum in the plane generated by the minor axes of the ellipses formed by each cross section.

La compression des cellules piézoélectriques de chaque pilier est nécessaire pour éviter le bris de la céramique lorsque les piliers sont sollicités en extension.The compression of the piezoelectric cells of each pillar is necessary to avoid breakage of the ceramic when the pillars are stressed in extension.

Dans un mode de réalisation décrit dans la demande de brevet européen 0 215 657, une première précontrainte est appliquée sur des empilements de cellules piézoélectriques lors de l'assemblage des empilements à l'intérieur de la coque. Les empilements s'étendent, symétriquement de part et d'autre de moyens mécaniques de calage centrés à l'intérieur de la coque, suivant le grand axe de la section droite elliptiques de la coque. Cette précontrainte, assure le maintien des empilements en appui respectivement par une première extrémité sur les moyens de calage et par une deuxième extrémité sur la partie intérieure de la coque correspondant à une extrémité du grand axe de l'ellipse. La précontrainte est ajustée en fonction de la profondeur opérationnelle d'immersion du transducteur pour compenser les forces hydrostatiques exercées sur l'extérieur de la coque et garantir le maintien constant des empilements pour le bon fonctionnnement du transducteur.In an embodiment described in European patent application 0 215 657, a first prestressing is applied to stacks of piezoelectric cells during the assembly of the stacks inside the shell. The stacks extend, symmetrically on either side of mechanical wedging means centered inside the hull, along the major axis of the elliptical cross section of the hull. This prestressing ensures the maintenance of the stacks in support respectively by a first end on the wedging means and by a second end on the inner part of the shell corresponding to one end of the major axis of the ellipse. The preload is adjusted as a function of the operational depth of immersion of the transducer to compensate for the hydrostatic forces exerted on the outside of the hull and guarantee the constant maintenance of the stacks for the proper functioning of the transducer.

Les moyens mécaniques de calage comportent une pièce tronconique permettant à partir de son déplacement vertical de transmettre la force de pression nécessaire sur les empilements.The mechanical wedging means comprise a frustoconical part making it possible, from its vertical displacement, to transmit the necessary pressure force on the stacks.

Le déplacement de la pièce tronconique est assuré par le serrage ou le desserrage d'une vis fixée sur sa partie supérieure. Le serrage détermine l'amplitude de la force de précontrainte à appliquer sur les empilements.The movement of the frustoconical part is ensured by tightening or loosening a screw fixed on its upper part. The tightening determines the amplitude of the prestressing force to be applied to the stacks.

La vis peut être remplacée par un bélier hydraulique et la pression exercée sur le bélier est déterminée à partir d'un capteur de pression. Le capteur mesure l'amplitude de la pression hydrostatique appliquée sur la coque du transducteur et permet d'ajuster la pression exercée sur le bélier.The screw can be replaced by a hydraulic ram and the pressure exerted on the ram is determined from a pressure sensor. The sensor measures the amplitude of the hydrostatic pressure applied to the shell of the transducer and makes it possible to adjust the pressure exerted on the ram.

Ce mode de réalisation a d'une part pour inconvénient que la précontrainte exercée sur les empilements pendant l'immersion est dépendante des forces hydrostatiques exercées sur la coque et que l'utilisation d'un tel transducteur est limitée par la tenue mécanique en compression des cellules piézoélecriques. Cet inconvénient est observé également dans le transducteur selon le brevet FR-A-2 361 033. Ce mode de réalisation a d'autre part pour inconvénient qu'il nécessite un moyen de mesure tel qu'un capteur pour mesurer la pression hydrostatique et un moyen de commande utilisant cette mesure pour commander un bélier hydraulique.On the one hand, this embodiment has the drawback that the prestressing exerted on the stacks during immersion is dependent on the hydrostatic forces exerted on the shell and that the use of such a transducer is limited by the mechanical resistance in compression of the piezoelectric cells. This drawback is also observed in the transducer according to patent FR-A-2 361 033. This embodiment also has the drawback that it requires a measurement means such as a sensor for measuring the hydrostatic pressure and a control means using this measurement to control a hydraulic ram.

Le but de l'invention est de pallier les inconvénients précités.The object of the invention is to overcome the aforementioned drawbacks.

A cet effet, l'invention a pour objet un transducteur flextenseur composé d'une coque, flexible et étanche, à paroi latérale cylindrique de section droite elliptique comportant au moins deux empilements de cellules piézoélectriques alignés sur un même axe longitudinal et maintenus en appui par une de leur première extrémité sur deux parties opposées de la coque par un dispositif fluidique, caractérisé en ce que les empilements de cellules piézoélectriques sont maintenus respectivement autour d'une tige et munis respectivement à leurs extrémités de deux pièces mécaniques pour établir une force de précontrainte indépendante de la pression hydrostatique exercée sur la coque du transducteur lors de son immersion, en ce que le dispositif fluidique comporte une cavité dans laquelle sont introduites les deuxièmes extrémités des empilements, remplie par un fluide sous pression provenant d'un réservoir extérieur placé à la même profondeur d'immersion que le transducteur, pour assurer le maintien en appui sur la coque de la première extrémité de chacun des empilements sous l'effet de la pression du fluide exercée sur leurs deuxièmes extrémités et compenser dans la cavité l'effet de la pression hydrostatique exercée sur la coque.To this end, the subject of the invention is a flextensor transducer composed of a flexible and waterproof shell with a cylindrical side wall of elliptical cross section comprising at least two stacks of piezoelectric cells aligned on the same longitudinal axis and held in abutment by one of their first end on two opposite parts of the shell by a fluidic device, characterized in that the stacks of piezoelectric cells are maintained respectively around a rod and provided respectively at their ends with two mechanical parts to establish a prestressing force independent of the hydrostatic pressure exerted on the shell of the transducer during its immersion, in that the fluidic device comprises a cavity into which the second ends of the stacks are introduced, filled with a fluid under pressure coming from an external reservoir placed at the same immersion depth as the transducer, to ensure that the first end of each of the stacks remains supported on the shell under the effect of the pressure of the fluid exerted on their second ends and compensate in the cavity for the effect of the hydrostatic pressure exerted on the hull.

L'invention a pour principal avantage qu'elle permet d'une part, de rendre indépendante la précontrainte exercée sur les empilements de la pression hydrostatique exercée sur la coque, et de la sorte, les transducteurs ainsi réalisés peuvent fonctionner à des immersions très supérieures aux immersions habituelles, et d'autre part, de n'utiliser qu'un moyen d'asservissement direct de la pression hydrostatique appliquée sur la coque du transducteur à la pression appliquée sur les empilements de cellules piézoélectriques.The main advantage of the invention is that it makes it possible, on the one hand, to make the prestressing exerted on the stacks independent of the hydrostatic pressure exerted on the hull, and in this way, the transducers thus produced can operate at much higher immersions. to the usual immersions, and on the other hand, to use only a means of direct servo-control of the hydrostatic pressure applied to the shell of the transducer to the pressure applied to the stacks of piezoelectric cells.

D'autres caractéristiques et avantages de l'invention apparaîtront ci-après à l'aide de la description faite en regard des dessins annexés qui représentent :

  • la figure 1, un mode de réalisation d'un transducteur selon l'invention, et
  • la figure 2, un assemblage d'un peigne de piliers à l'intérieur d'une coque d'un transducteur selon l'invention.
Other characteristics and advantages of the invention will appear below with the aid of the description given with reference to the appended drawings which represent:
  • FIG. 1, an embodiment of a transducer according to the invention, and
  • Figure 2, an assembly of a pillar comb inside a shell of a transducer according to the invention.

Un premier mode de réalisation d'un transducteur flextenseur selon l'invention est décrit ci-après à l'aide de la figure 1.A first embodiment of a flexuring transducer according to the invention is described below with the aid of FIG. 1.

Ce transducteur comprend une coque flexible et étanche, à paroi latérale cylindrique de section droite elliptique 1, renfermant au moins deux piliers 2 et 3 formés respectivement par un empilement, autour d'une tige 4 et 5, d'une pluralité de cellules piézoélectriques, 6i et 7i, en céramique.This transducer comprises a flexible and watertight shell, with a cylindrical lateral wall of elliptical cross section 1, containing at least two pillars 2 and 3 formed respectively by a stack, around a rod 4 and 5, of a plurality of piezoelectric cells, 6i and 7i, ceramic.

Dans cet exemple, les piliers 2 et 3 sont munis à leurs extrémités de deux pièces mécaniques 8 et 9 respectivement 10, 11 pour établir la force de précontrainte des piliers 2 et 3 indépendante de la pression hydrostatique exercée sur la coque 1 lors de son immersion. Pour assurer le maintien des deux piliers 2 et 3 et faire en sorte qu'ils se comportent comme un seul pilier, un dispositif fluidique 12 est disposé entre les extrémités des deux piliers 2 et 3 les plus éloignées de la coque 1.In this example, the pillars 2 and 3 are provided at their ends with two mechanical parts 8 and 9 respectively 10, 11 to establish the prestressing force of the pillars 2 and 3 independent of the hydrostatic pressure exerted on the shell 1 during its immersion . To maintain the two pillars 2 and 3 and ensure that they behave as a single pillar, a fluidic device 12 is disposed between the ends of the two pillars 2 and 3 furthest from the shell 1.

Ce dispositif est constitué d'une cavité 13 remplie d'huile reliée à un réservoir extérieur 14 par un tuyau capillaire 15. La cavité 13 est réalisée, par exemple, au moyen d'une pièce de révolution formant boîtier entourant les deux extrémités des piliers 2 et 3. Au moins deux joints élastomères 16, 17 assurent l'étanchéité de la cavité 13 avec les extrémités des piliers 2 et 3.This device consists of a cavity 13 filled with oil connected to an external reservoir 14 by a capillary pipe 15. The cavity 13 is produced, for example, by means of a part of revolution forming a housing surrounding the two ends of the pillars 2 and 3. At least two elastomeric seals 16, 17 seal the cavity 13 with the ends of the pillars 2 and 3.

L'immersion du réservoir 14 et du transducteur étant la même, la pression qui s'exerce sur la coque 1 est compensée par la pression de l'huile de sorte que les piliers 2 et 3 se trouvent toujours appliqués sur la coque 1.The immersion of the reservoir 14 and the transducer being the same, the pressure exerted on the shell 1 is compensated by the pressure of the oil so that the pillars 2 and 3 are always applied to the shell 1.

En dynamique, la raideur du film d'huile est élevée à la fréquence de fonctionnement, et procure une masse élevée au centre de la cavité 13 de manière identique à l'art connu. De plus la vitesse de vibration étant faible puisque l'on est au point nodal, les joints d'étanchéité 16, 17 travaillent dans de bonnes conditions.In dynamics, the stiffness of the oil film is high at the operating frequency, and provides a high mass in the center of the cavity 13 in a manner identical to the known art. In addition, the vibration speed being low since we are at the nodal point, the seals 16, 17 work in good conditions.

Pour obtenir un fonctionnement correct lorsque le mouvement est en extension et entraîne une dépression de l'huile, cette dernière est mise en surpression par rapport à la pression hydrostatique extérieure.To obtain correct operation when the movement is in extension and results in a vacuum of the oil, the latter is put in overpressure relative to the external hydrostatic pressure.

Outre le fait que dans ce mode de réalisation la tenue à la pression du transducteur est remarquable son montage est aussi très simple à réaliser. Il s'effectue en effet en insérant en une seule opération l'ensemble piliers-boîtier, relié au réservoir 14 dans la coque 1, les deux piliers 2 et 3 étant en contact. Il suffit ensuite de mettre en pression l'huile pour que les deux piliers 2, 3 s'écartent et que le transducteur soit prêt à fonctionner. Avantageusement chaque pilier 2, 3 peut éventuellement être mis en appui sur la coque 1 par l'intermédiaire d'un logement approprié dans la coque 1.Besides the fact that in this embodiment the pressure resistance of the transducer is remarkable, its mounting is also very simple to carry out. It is effected by inserting in a single operation the pillar-housing assembly, connected to the reservoir 14 in the shell 1, the two pillars 2 and 3 being in contact. Then simply pressurize the oil so that the two pillars 2, 3 move apart and the transducer is ready to operate. Advantageously, each pillar 2, 3 can optionally be supported on the shell 1 by means of an appropriate housing in the shell 1.

Selon encore une autre variante de réalisation, le montage d'un transducteur peut encore être effectué suivant un procédé "collectif", de la façon représentée sur la figure 2, en rendant le boîtier fluidique 12 commun à tous les piliers 2i. Dans ces conditions l'ensemble boîtier-piliers qui a la forme d'une "arête de poisson" est introduit dans la coque 1 en une seule opération et leur boîtier commun 12 et reliée à un seul réservoir d'huile 14 par le tuyau capillaire 15.According to yet another alternative embodiment, the mounting of a transducer can also be carried out according to a "collective" method, as shown in FIG. 2, by making the fluid housing 12 common to all the pillars 2 i . Under these conditions the housing-pillar assembly which has the shape of a "fishbone" is introduced into the shell 1 in a single operation and their common housing 12 and connected to a single oil tank 14 by the capillary pipe 15.

Claims (4)

Transducteur flextenseur composé d'une coque, flexible et étanche, à paroi latérale cylindrique de section droite elliptique (1) comportant au moins deux empilements (2 et 3) de cellules piézoélectriques (6i et 7i) alignés sur un même axe longitudinal et maintenus en appui par une de leur première extrémité sur deux parties opposées de la coque (1) par un dispositif fluidique (12), caractérisé en ce que les empilements (2 et 3) de cellules piézoélectriques (6i et 7i) sont maintenus respectivement autour d'une tige (4 et 5) et munis respectivement à leurs extrémités de deux pièces mécaniques (8, 9 et 10, 11) pour établir une force de précontrainte indépendante de la pression hydrostatique exercée sur la coque (1) du transducteur lors de son immersion, en ce que le dispositif fluidique (12) comporte une cavité (13) dans laquelle sont introduites les deuxièmes extrémités des empilements (2 et 3), remplie par un fluide sous pression provenant d'un réservoir (14) extérieur placé à la même profondeur d'immersion que le transducteur, pour assurer le maintien en appui sur la coque (1) de la première extrémité de chacun des empilements (2 et 3) sous l'effet de la pression du fluide exercée sur leurs deuxièmes extrémités et compenser dans la cavité (13) l'effet de la pression hydrostatique exercée sur la coque (1).Flextensor transducer composed of a shell, flexible and waterproof, with cylindrical lateral wall of elliptical cross section (1) comprising at least two stacks (2 and 3) of piezoelectric cells (6i and 7i) aligned on the same longitudinal axis and maintained in support by one of their first end on two opposite parts of the shell (1) by a fluidic device (12), characterized in that the stacks (2 and 3) of piezoelectric cells (6i and 7i) are maintained respectively around a rod (4 and 5) and provided respectively at their ends with two mechanical parts (8, 9 and 10, 11) to establish a prestressing force independent of the hydrostatic pressure exerted on the shell (1) of the transducer during its immersion , in that the fluidic device (12) comprises a cavity (13) into which the second ends of the stacks (2 and 3) are introduced, filled with a pressurized fluid from a reservoir (1 4) exterior placed at the same immersion depth as the transducer, to ensure that the first end of each of the stacks (2 and 3) remains supported on the shell (1) under the effect of the pressure of the fluid exerted on their second ends and compensate in the cavity (13) for the effect of the hydrostatic pressure exerted on the shell (1). Transducteur selon la revendication 1, caractérisé en ce qu'il comporte au moins deux joints élastomères (16 et 17) assurant l'étanchéité de la cavité (13) avec les extrémités des empilements (2 et 3).Transducer according to claim 1, characterized in that it comprises at least two elastomeric seals (16 and 17) ensuring the tightness of the cavity (13) with the ends of the stacks (2 and 3). Transducteur selon l'une quelconque des revendications 1 et 2, caractérisé en ce qu'il comporte un tuyau capillaire (15) amenant le fluide contenu dans le réservoir (14) à l'intérieur de la cavité (13).Transducer according to any one of claims 1 and 2, characterized in that it comprises a capillary pipe (15) bringing the fluid contained in the reservoir (14) inside the cavity (13). Transducteur selon l'une quelconque des revendications 1 à 3, caractérisé en ce que le fluide sous pression est de l'huile.Transducer according to any one of claims 1 to 3, characterized in that the pressurized fluid is oil.
EP19930117557 1988-11-04 1989-11-03 Flextensional transducer Withdrawn EP0583805A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8814416 1988-11-04
FR8814416A FR2639786B1 (en) 1988-11-04 1988-11-04 FLEXTENING TRANSDUCER

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EP19930117557 Withdrawn EP0583805A1 (en) 1988-11-04 1989-11-03 Flextensional transducer
EP89403032A Ceased EP0367681A1 (en) 1988-11-04 1989-11-03 Flextensional transducer

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EP (2) EP0583805A1 (en)
FR (1) FR2639786B1 (en)

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US5497357A (en) * 1988-12-23 1996-03-05 Alliedsignal Inc. Shock-resistant flextensional transducer
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US5042611A (en) * 1990-05-18 1991-08-27 Texaco Inc. Method and apparatus for cross-well seismic surveying
FR2663182B1 (en) * 1990-06-12 1992-09-18 Grosso Gilles UNDERWATER ELECTRO-ACOUSTIC TRANSDUCER.
FR2663805B1 (en) * 1990-06-26 1992-09-11 Thomson Csf METHOD OF MANUFACTURING A MAGNETOSTRICTIVE ELEMENT FOR THE PRODUCTION OF ELECTRO-ACOUSTIC TRANSDUCERS AND ELECTRO-ACOUSTIC TRANSDUCER PRODUCED USING SUCH ELEMENTS.
FR2672179B1 (en) * 1991-01-25 1993-04-16 Thomson Csf FLEXIBLE ACOUSTIC TRANSDUCER FOR DEEP IMMERSION.
US5155709A (en) * 1991-07-10 1992-10-13 Raytheon Company Electro-acoustic transducers
AU692960B2 (en) * 1994-12-23 1998-06-18 Marschall Acoustics Pty Ltd Hydrophone
US5926439A (en) * 1998-12-21 1999-07-20 The United States Of America As Represented By The Secretary Of The Navy Flextensional dual-section push-pull underwater projector
US5949741A (en) * 1998-12-21 1999-09-07 The United States Of America As Represented By The Secretary Of The Navy Dual-section push-pull underwater projector
US6076630A (en) * 1999-02-04 2000-06-20 Western Atlas International, Inc. Acoustic energy system for marine operations
FR2809580B1 (en) 2000-05-26 2002-08-30 Thomson Marconi Sonar Sas ELECTRODYNAMIC TRANSDUCER FOR UNDERWATER ACOUSTICS
WO2007145734A2 (en) 2006-06-07 2007-12-21 Exxonmobil Upstream Research Company Compressible objects having partial foam interiors combined with a drilling fluid to form a variable density drilling mud
US8088716B2 (en) 2004-06-17 2012-01-03 Exxonmobil Upstream Research Company Compressible objects having a predetermined internal pressure combined with a drilling fluid to form a variable density drilling mud
WO2007145735A2 (en) 2006-06-07 2007-12-21 Exxonmobil Upstream Research Company Method for fabricating compressible objects for a variable density drilling mud
CN100570708C (en) * 2006-03-17 2009-12-16 中国科学院声学研究所 A kind of ultra-low frequency underwater acoustic transducer
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Also Published As

Publication number Publication date
US4970706A (en) 1990-11-13
FR2639786B1 (en) 1991-07-26
FR2639786A1 (en) 1990-06-01
EP0367681A1 (en) 1990-05-09

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