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EP0005409A2 - Piezoelectric transducers with mechanical amplification for very low frequencies and acoustic antennas - Google Patents

Piezoelectric transducers with mechanical amplification for very low frequencies and acoustic antennas Download PDF

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Publication number
EP0005409A2
EP0005409A2 EP79400291A EP79400291A EP0005409A2 EP 0005409 A2 EP0005409 A2 EP 0005409A2 EP 79400291 A EP79400291 A EP 79400291A EP 79400291 A EP79400291 A EP 79400291A EP 0005409 A2 EP0005409 A2 EP 0005409A2
Authority
EP
European Patent Office
Prior art keywords
base plate
side plates
transducer according
pavilion
stacks
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
EP79400291A
Other languages
German (de)
French (fr)
Other versions
EP0005409A3 (en
EP0005409B1 (en
Inventor
Bernard Tocquet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Direction General pour lArmement DGA
Etat Francais
Original Assignee
Direction General pour lArmement DGA
Etat Francais
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Filing date
Publication date
Application filed by Direction General pour lArmement DGA, Etat Francais filed Critical Direction General pour lArmement DGA
Publication of EP0005409A2 publication Critical patent/EP0005409A2/en
Publication of EP0005409A3 publication Critical patent/EP0005409A3/en
Application granted granted Critical
Publication of EP0005409B1 publication Critical patent/EP0005409B1/en
Expired legal-status Critical Current

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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
    • G10K11/08—Non-electric sound-amplifying devices, e.g. non-electric megaphones
    • 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
    • G10K9/00—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers
    • G10K9/12—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated
    • G10K9/121—Flextensional transducers

Definitions

  • the subject of the invention is piezoelectric transducers, for very low frequencies, between a few Hz and 500 Hz, which comprise a mechanical amplifier and antennas constructed with such transducers.
  • the technical sector of the invention is that of the construction of acoustic devices used in particular in underwater acoustics.
  • the objective of the present invention is to overcome this difficulty by mechanically amplifying the deformations of the piezoelectric transducers, so that it is possible to construct piezoelectric transducers of high power for very low frequencies.
  • each stack of piezoelectric elements comprises a central fixed point and two half stacks located: on either side of said fixed point.
  • a transducer according to the invention comprises two identical sub-assemblies located on either side of the same base plate and symmetrical with respect thereto.
  • the invention results in new piezoelectric transducers, transmitters or receivers, making it possible to obtain large amplitudes and therefore high powers at very low frequencies between a few Hz and 500 Hz, while using transducers having relatively small dimensions.
  • the amplitude of the deformations of the piezoelectric stacks is multiplied by the mechanical amplifier associated with these stacks.
  • This amplifier consists on the one hand by the two levers which multiply the amplitude of the oscillations by a DC ficient equal to the ratio between the two lever arms and, on the other hand, by the elastic membrane which serves as a flag and which connects between them the free ends of the two levers so that when the spacing between the ends of the two levers varies in one direction or the other, this variation results in flexural deformations of the membrane and the amplitude of the deformations at the center of the membrane is greater than the amplitude of the variations in spacing of the ends of the two levers.
  • the elastic membrane constitutes a pavilion which can be placed in contact with water and which can therefore transmit water or pick up large amplitude acoustic waves while the deformations of the piezoelectric elements are much smaller than the deformations of the membrane flexible.
  • the flexible membrane can be flat or, preferably, curved.
  • the bending of the flexible membrane is obtained by means of a bending prestress of said plate, so that the latter remains constantly compressed even when the spacing between the two ends of the levers is maximum.
  • the embodiment comprising two identical sub-assemblies arranged symmetrically with respect to the same base plate has the advantage of making it possible to reduce the thickness of this base plate.
  • the transducers according to the invention make it possible to construct antennas comprising a base plate, flat or cylindrical, on which is arranged a network of transducers aligned along lines and / or columns.
  • An advantage of the devices according to the invention lies in the fact that they are mechanical devices having several natural resonant frequencies including certain very low frequencies between a few Hertz and 500 Hz, which makes it possible to choose the lowest of these resonance frequencies and to obtain a SV sensitivity curve measured in decibels having a pronounced peak, located in the very low frequency band.
  • FIGS 1, 2 and 3 show a piezoelectric transducer intended either to emit or to pick up acoustic waves in water.
  • This transducer comprises one or more stacks 1 of piezoelectric elements.
  • each stack is composed of piezoelectric elements 2, for example plates of piezoelectric ceramic, between which electrodes 3 are inserted.
  • the electrodes 3 are connected alternately on one or the other of two electrical conductors 4a and 4b, of opposite polarity.
  • the elements 2 and the electrodes 3 are held tight by a central prestressing rod 5, of axis x xl which is threaded at its two ends and by two nuts 6a, 6b which are screwed on the two threaded ends in order to put the rod 5 in tension.
  • Such a stack of piezoelectric elements and electrodes is well known and we know that it deforms parallel to the axis x xl if a sinusoidal voltage is applied between the conductors 4a and 4b and that reciprocally, a sinusoidal voltage between conductors 4a and 4b if the transducer serves as a receiver of acoustic waves.
  • each piezoelectric element is limited by the nature of the materials If one wants to transmit or receive acoustic TRE p frequency waves having a sufficient power, it is necessary used- stacks comprising a very large number of elements the transducers become very bulky.
  • a submerged transducer makes it possible to obtain large amplitudes of deformation of the horn, that is to say of the active surface which is in contact with water and which transmits the acoustic waves to the water in the case of a transmitter or which receives the acoustic waves in the case of a receiver, and this result is achieved by means of a transducer whose dimensions remain relatively reduced, if we compare them with those which would be necessary to obtain the same amplitudes in the case of a traditional transducer comprising only a stack of piezoelectric elements.
  • a transducer according to the invention comprises a very rigid base plate 7. It comprises two flat side plates 8a and 8b which are identical and perpendicular to the base plate 7, on the same side thereof. These side plates have, for example, a rectangular shape.
  • the lower edge of each plate 8a and 8b is connected to the base plate, for example by means of plates 9a and 9b which are each composed of two half plates which are fixed to the base plate 7 by screws 10 and which enclose between them the lower edge of the plates 8a and 8b.
  • Each plate 8a, 8b comprises, along its lower edge, immediately above the plates 9a and 9b, a thinning 11, constituted for example by two grooves 11a and 11b, situated on either side of the plate so that the plates 8a and 8b can deform by pivoting around the thinning 11.
  • the plates 8a and 8b are fixed in console on the plate 7 by semi-recesses.
  • this semi-embedding can be replaced by an articulation around an axis parallel to the lower edge of each plate.
  • each side plate such as 8a comprises, along its lower edge, a bead 12 of circular section, which is engaged in a groove 13 of circular section, hollowed out in the base plate 7.
  • Two half plates 14a and 14b are screwed onto the plate 7 and maintain the bead 12 in its housing while allowing it to pivot.
  • this articulation can be replaced by any other equivalent type of articulation.
  • the stacks 1a and 1b extend above the base plate 7, perpendicular to the two plates Sa and 8b.
  • the two axially opposite ends of the stack 1 are pressed against the internal faces of the two plates 8a and 8b slightly above the thinning 11.
  • the support is produced by means of an intermediate support piece 15a, 15b .
  • a support piece 15 is shown in perspective in FIG. 5. This piece has a first flat side face 16 which is pressed against one of the side plates 8 and a second side face 17, opposite to the face 16, which is pressed against one end of the stack 1.
  • the face 17 is a portion of cylindrical surface, in an arc of a circle, so that the support of the stack on the support face takes place along a line which is the median generatrix 18 of the face 17
  • Each part 15 has two holes 19a and 19b for the passage of the extensions of the rod 5 which pass through the plates 8a and 8b. Nuts 20a and 20b are screwed onto these extensions to keep the stacks 1a and 1b in place.
  • the cylindrical shape of the faces 17 of the support piece 15 makes it possible to precisely determine the support line 18 and therefore the distance which separates it from the line around which the plates 8a and 8b can pivot, that is ie thinning 11 or the center of the bead 12.
  • the plates 8a and 8b act as levers, the thinning 11 or the beads 12 of which constitute the fulcrum, while the distance separating this fulcrum 18 constitutes the small arm of the lever. It is specified that the support pieces 15a and 15b can be reversed, so that their cylindrical face 17 is placed in contact with a side plate 8a or 8b.
  • each stack 1a, 1b is composed of two half stacks symmetrical with respect to a central fixed point 21 which is constituted for example by a plate fixed to the base plate 7 by screws 22.
  • the transducer shown in Figures 1, 2 and 3 further comprises a horn 23 which is the active surface, in acoustic contact with the water.
  • This pavilion is constituted by an elastic and flexible membrane, for example a thin plate of spring steel having a thickness of a few millimeters.
  • This plate is fixed by any means along each of its two lateral edges to an upper edge of one of the lateral plates 8a and 8b.
  • the two lateral edges of the plate 23 are folded back to form folds 23a and 23b and these folds are held pinched between a plate 8a or 8b and a fixing plate 24a, 24b fixed to the plate 8a or 8b by screws 25. Screws 26 screwed into the thickness of the plates 8a and 8b can reinforce this fixing.
  • the plate 23 is curved, the convex face being turned, preferably, on the side opposite to the base plate 7.
  • a plate is used having a width in the direction parallel to the axis x xl slightly greater than the spacing between the two side plates 8a and 8b and it is slightly compressed in the direction parallel to the axis x xl before fixing it along the two upper edges of the plates 8a and 8b.
  • the transducer according to FIGS. 1 to 3 comprises a sealed housing composed of two flanges 27a and 27b parallel to the plates 8a and 8b and of two lateral flanges 28a and 28b, visible in FIG. 3 and a flexible membrane 29, forming a skin of sealing, which envelops the flanges 27a, 27b, 28a, 28b and the roof 23.
  • the skin 29 is made of a material having an acoustic impedance close to that of water so that it is acoustically transparent and that it does not disturb the transmission of waves between the water and the active surface of the roof 23. It is glued to the pavilion 23, so that it follows the movements thereof.
  • the skin 29 is for example a thin skin of rubber or flexible plastic. A slight clearance exists between, on the one hand, the plates 8a, 8b and the roof 23 and on the other hand, the lateral faces 27a, 27b, 28a, 28b of the housing, so that the housing does not impede movement flag and side plates 8a, 8b.
  • the inside of the waterproof case is filled with gas. If the transducer is to be used in immersion, this gas is maintained in equilibrium with the outside, for example by means of a source of compressed gas provided with a regulator which is adjusted as a function of the depth.
  • the two walls 27a and 27b of the housing can be eliminated and the membrane 29 can be glued directly to the two external faces 8a and 8b.
  • the plates 8a and 8b constitute acoustically active surfaces.
  • Figures 1 and 3 show a sealed connector 30 through which the electrical conductors 4a and 4b pass through the wall 28b.
  • this transducer is as follows.
  • the stack 1 deforms longitudinally along the axis x xl.
  • the deformations are communicated to the two levers 8a and 8b which deform by pivoting around their fulcrum.
  • the displacements of the upper ends of the levers 8a and 8b are multiplied by the ratio between the two lever arms.
  • the variations in spacing between the two upper edges of the two lever: 8a and 8b produce flexural deformations of the elastic membrane 23.
  • the displacements at the center of the membrane in the direction perpendicular to the base plate 7 are greater than the displacements of the upper ends of the two levers 8a and 8b.
  • FIG. 6 represents measurements of the sensitivity SV of a transducer according to the invention as a function of the frequency. It is recalled that the sensitivity SV measured in decibels corresponds to 20 times the logarithm of the ratio between the acoustic pressure measured either in micro bar or in micro pascal and the voltage in volts.
  • FIG. 6 shows on the abscissa a frequency range between 80 Hz and 180 Hz.
  • the sensitivity measured according to the reference y bar per volt is represented on the left and on the right according to the reference y pascal / volt.
  • a maximum sensitivity is obtained for a resonance frequency of the order of 125 Hz.
  • FIG. 7 represents a longitudinal section of an alternative embodiment of a transducer according to the invention.
  • FIGS. 1, 2 and 3 This consists of two half transducers which are arranged symmetrically with respect to a base plate 7 to the two half transducers.
  • Each of the two half transducers is identical to that which is represented in FIGS. 1, 2 and 3 and the parts homologous to those of these figures are represented by the same references.
  • Figure 7 there is shown in Figure 7 an embodiment according to the variant in which the side walls 27a and 27b of the housing are removed and the skin 29 is bonded directly to the pavilions 23 and the side flanges 8a and 8b.
  • An advantage of this embodiment is that it makes it possible to use a less rigid base plate 7 because it is bi-symmetrically stressed by the two half transducers.
  • a transducer according to Figure 7 is very omnidirectional.
  • FIG. 8 schematically represents an exemplary embodiment of an acoustic antenna comprising sixteen transducers according to the invention, for example 25 hydrophones, arranged in a network along five lines LI to L5 and five columns CI to C5.
  • Each transducer is represented diagrammatically by a square of which two opposite sides are in double line and represent the two side plates 8a and 8b of a transducer.
  • All the transducers are fixed on the same rigid plate 31 which serves as a common base plate for all the transducers.
  • the plate 31 can be flat, curved or cylindrical depending on the shape of the antenna.
  • Two networks of transducers can be arranged symmetrically on either side of the plate 31.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)

Abstract

L'invention a pour objet de nouveaux transducteurs piézoélectriques avec amplificateur mécanique incorporé. Un transducteur selon l'invention comporte une plaque de base rigide 7; deux plaques latérales 8a et 8b dont le bord inférieur est relié à la plaque 7 par un amincissement 11; un empilement 1 d'éléments piézoélectriques 2 alternant avec des électrodes 3; un pavillon 23 formé d'une membrane élastique et flexible qui relie entre eux les bords supérieurs des deux plaques 8a et 8b; un boîtier 27a, 27b et une peau d'étanchéïté 29 transparente acoustiquement. Une application est l'émission ou la réception d'ondes acoustiques de grande puissance dans les très basses fréquences compris par exemple entre quelques Hertz et 500 Hz.The invention relates to new piezoelectric transducers with incorporated mechanical amplifier. A transducer according to the invention comprises a rigid base plate 7; two side plates 8a and 8b whose lower edge is connected to the plate 7 by a thinning 11; a stack 1 of piezoelectric elements 2 alternating with electrodes 3; a pavilion 23 formed of an elastic and flexible membrane which interconnects the upper edges of the two plates 8a and 8b; a housing 27a, 27b and an acoustically transparent sealing skin 29. One application is the emission or reception of high power acoustic waves in very low frequencies, for example between a few Hertz and 500 Hz.

Description

L'invention a pour objet des transducteurs piézoéléctri- ques, pour de très basses fréquences, entre quelques Hz et 500 Hz, qui comportent un amplificateur mécanique et des antennes construites avec de tels transducteurs.The subject of the invention is piezoelectric transducers, for very low frequencies, between a few Hz and 500 Hz, which comprise a mechanical amplifier and antennas constructed with such transducers.

Le secteur technique de l'invention est celui de la construction de dispositifs acoustiques utilisés notamment en acoustique sous-marine.The technical sector of the invention is that of the construction of acoustic devices used in particular in underwater acoustics.

On sait que pour une intensité déterminée, l'amplitude des vibrations acoustiques est d'autant plus grande que la fréquence est faible. Aux très basses fréquences, de quelques Hz à 500 Hz, les performances des transducteurs piézoélectriques sont limitées par les propriétés des matériaux piézoélectriques qui ne permettent pas d'atteindre des amplitudes de vibration suffisantes.It is known that for a determined intensity, the amplitude of the acoustic vibrations is all the greater the lower the frequency. At very low frequencies, from a few Hz to 500 Hz, the performance of piezoelectric transducers is limited by the properties of piezoelectric materials which do not allow sufficient amplitudes of vibration to be achieved.

L'objectif de la présente invention est de pallier cette difficulté en amplifiant mécaniquement les déformations des transducteurs piézoélectriques, de sorte que l'on puisse construire des transducteurs piézoélectriques de grande puissance pour de très basses fréquences.The objective of the present invention is to overcome this difficulty by mechanically amplifying the deformations of the piezoelectric transducers, so that it is possible to construct piezoelectric transducers of high power for very low frequencies.

Cet objectif est atteint au moyen de transducteurs piézoélectriques pour très basses fréquences qui comportent :

  • - au moins un empilement d'éléments piézoélectriques ayant deux extrémités axialement opposées ;
  • - deux leviers placés de part et d'autre desdits empilements, de telle sorte que chacune des deux extrémités de chaque empilement s'appuie sur un des deux leviers à proximité du point d'appui de celui-ci ;
  • - et un pavillon constitué par une membrane élastique flexible qui relie entre elles les extrémités des deux leviers.
This objective is achieved by means of piezoelectric transducers for very low frequencies which include:
  • - at least one stack of piezoelectric elements having two axially opposite ends;
  • - Two levers placed on either side of said stacks, so that each of the two ends of each stack is supported on one of the two levers near the fulcrum thereof;
  • - And a pavilion constituted by a flexible elastic membrane which connects the ends of the two levers together.

Selon un mode de réalisation préférentiel, un transducteur selon l'invention comporte :

  • - une plaque de base rigide ;
  • - deux plaques latérales planes, qui sont situées du même côté de ladite plaque de base et qui sont reliées à celle-ci par un semi-encastrement ou par une articulation le long de l'un de leurs bords ;
  • - au moins un empilement d'éléments piézoélectriques, ayant deux extrémités axialement opposées en contact respectivement avec chacune desdites plaques latérales à proximité du bord de celle-ci qui est relié à la plaque de base ;
  • - un pavillon constitué par une membrane élastique flexible qui relie entre eux les deux bords des deux plaques latérales qui sont opposés aux deux bords reliés à la plaque de base ;
  • - et un boîtier rempli de gaz, qui renferme lesdits empilements piézoélectriques et dont ledit pavillon constitue l'une des faces, lequel boîtier est enveloppé de façon étanche par une membrane déformable et transparente acoustiquement qui enveloppe également ledit pavillon.
According to a preferred embodiment, a transducer according to the invention comprises:
  • - a rigid base plate;
  • - two flat side plates, which are located on the same side of said base plate and which are connected to the latter by a semi-embedding or by a joint along one of their edges;
  • - At least one stack of piezoelectric elements, having two axially opposite ends in contact respectively with each of said side plates near the edge thereof which is connected to the base plate;
  • - a pavilion constituted by a flexible elastic membrane which connects the two edges of the two side plates which are opposite to the two edges connected to the base plate;
  • - And a gas-filled housing, which contains said piezoelectric stacks and of which said pavilion constitutes one of the faces, which housing is sealed in a sealed manner by a deformable and acoustically transparent membrane which also envelops said pavilion.

De préférence, chaque empilement d'éléments piézoélectriques comporte un point fixe central et deux demi empilements situé: de part et d'autre dudit point fixe.Preferably, each stack of piezoelectric elements comprises a central fixed point and two half stacks located: on either side of said fixed point.

Selon un mode de réalisation particulier, un transducteur selon l'invention comporte deux sous-ensembles identiques situés de part et d'autre d'une même plaque de base et symétriques par rapport à celle-ci.According to a particular embodiment, a transducer according to the invention comprises two identical sub-assemblies located on either side of the same base plate and symmetrical with respect thereto.

L'invention a pour résultat de nouveaux transducteurs piézoélectriques, émetteurs ou récepteurs, permettant d'obtenir de grandes amplitudes donc des puissances élevées dans de très basses fréquences comprises entre quelques Hz et 500 Hz, tout en utilisan des transducteurs ayant des dimensions relativement réduites.The invention results in new piezoelectric transducers, transmitters or receivers, making it possible to obtain large amplitudes and therefore high powers at very low frequencies between a few Hz and 500 Hz, while using transducers having relatively small dimensions.

L'amplitude des déformations des empilements piézoélectriques est multipliée par l'amplificateur mécanique associé à ces empilements.The amplitude of the deformations of the piezoelectric stacks is multiplied by the mechanical amplifier associated with these stacks.

Cet amplificateur est constitué d'une part par les deux leviers qui multiplient l'amplitude des oscillations par un cc ficient égal au rapport entre les deux bras de levier et,d'autre part, par la membrane élastique qui sert de pavillon et qui relie entre elles les extrémités libres des deux leviers de telle sorte que lorsque l'écartement entre les extrémités des deux leviers varie dans un sens ou dans l'autre, cette variation se traduit par des déformations en flexion de la membrane et l'amplitude des déformations au centre de la membrane est supérieur à l'amplitude des variations d'écartement des extrémités des deux leviers.This amplifier consists on the one hand by the two levers which multiply the amplitude of the oscillations by a DC ficient equal to the ratio between the two lever arms and, on the other hand, by the elastic membrane which serves as a flag and which connects between them the free ends of the two levers so that when the spacing between the ends of the two levers varies in one direction or the other, this variation results in flexural deformations of the membrane and the amplitude of the deformations at the center of the membrane is greater than the amplitude of the variations in spacing of the ends of the two levers.

La membrane élastique constitue un pavillon qui peut être placé au contact de l'eau et qui peut donc transmettre à l'eau ou capter des ondes acoustiques de grande amplitude alors que les déformations des éléments piézoélectriques sont beaucoup plus faibles que les déformations de la membrane flexible.The elastic membrane constitutes a pavilion which can be placed in contact with water and which can therefore transmit water or pick up large amplitude acoustic waves while the deformations of the piezoelectric elements are much smaller than the deformations of the membrane flexible.

La membrane flexible peut être plane ou, de préférence, cintrée. Le cintrage de la membrane flexible est obtenu au moyen d'une précontrainte en flexion de ladite plaque, de telle sorte que celle-ci reste constamment comprimée même lorsque l'écartement entre les deux extrémités des leviers est maximum.The flexible membrane can be flat or, preferably, curved. The bending of the flexible membrane is obtained by means of a bending prestress of said plate, so that the latter remains constantly compressed even when the spacing between the two ends of the levers is maximum.

Le mode de réalisation comportant deux sous-ensembles identiques disposés symétriquement par rapport à une même plaque de base, présente l'avantage de permettre de réduire l'épaisseur de cette plaque de base.The embodiment comprising two identical sub-assemblies arranged symmetrically with respect to the same base plate has the advantage of making it possible to reduce the thickness of this base plate.

Les transducteurs selon l'invention permettent de construire des antennes comportant une plaque de base, plane ou cylindrique, sur laquelle est disposée un réseau de transducteurs alignés suivant des lignes et/ou des colonnes.The transducers according to the invention make it possible to construct antennas comprising a base plate, flat or cylindrical, on which is arranged a network of transducers aligned along lines and / or columns.

Un avantage des dispositifs selon l'invention réside dans le fait qu'il s'agit de dispositifs mécaniques ayant plusieurs fréquences de résonance propres dont certaines fréquences très basses comprises entre quelques Hertz et 500 Hz, ce qui permet de choisir la plus basse de ces fréquences de résonnance et d'obtenir une courbe de sensibilité SV mesurée en décibels ayant un pic prononcé, situé dans la bande des très basses fréquences.An advantage of the devices according to the invention lies in the fact that they are mechanical devices having several natural resonant frequencies including certain very low frequencies between a few Hertz and 500 Hz, which makes it possible to choose the lowest of these resonance frequencies and to obtain a SV sensitivity curve measured in decibels having a pronounced peak, located in the very low frequency band.

La description suivante se réfère aux dessins annexés qui représentent, sans aucun caractère limitatif,. des exemples de réalisation de transducteurs et d'antennes selon l'invention.

  • La figure 1 est une coupe longitudinale selon I-I d'un transducteur selon l'invention.
  • La figure 2 est une vue en plan du transducteur selon la figure 1.
  • La figure 3 est une coupe transversale selon III-III.
  • La figure 4 est une coupe verticale partielle d'une variante de réalisation de la figure 1.
  • La figure 5 est une vue en perspective d'une pièce d'appu:
  • La figure 6 est une coupe représentant la sensibilité d'un transducteur selon les figures 1 et 2 en fonction de la fréquence
  • La figure 7 représente une variante de transducteur selon l'invention.
  • La figure 8 représente une antenne acoustique composée d'un réseau de transducteurs selon l'invention.
The following description refers to the appended drawings which represent, without any limiting character,. exemplary embodiments of transducers and antennas according to the invention.
  • Figure 1 is a longitudinal section along II of a transducer according to the invention.
  • FIG. 2 is a plan view of the transducer according to FIG. 1.
  • Figure 3 is a cross section along III-III.
  • FIG. 4 is a partial vertical section of an alternative embodiment of FIG. 1.
  • FIG. 5 is a perspective view of a support piece:
  • FIG. 6 is a section showing the sensitivity of a transducer according to FIGS. 1 and 2 as a function of the frequency
  • FIG. 7 represents a variant of a transducer according to the invention.
  • FIG. 8 represents an acoustic antenna composed of a network of transducers according to the invention.

Les figures 1, 2 et 3 représentent un transducteur piézoélectrique destiné, soit à émettre, soit à capter des ondes acoustiques dans l'eau. Ce transducteur comporte un ou plusieurs empilements 1 d'éléments piézoélectriques.Figures 1, 2 and 3 show a piezoelectric transducer intended either to emit or to pick up acoustic waves in water. This transducer comprises one or more stacks 1 of piezoelectric elements.

Dans le cas des figures, il comporte, par exemple deux empilements la et 1b. Chaque empilement est composé d'éléments piézoélectriques 2, par exemple des plaquettes d'une céramique piézoélectrique, entre lesquels sont intercalées des électrodes 3. Les électrodes 3 sont connectées alternativement sur l'un ou l'aut de deux conducteurs électriques 4a et 4b, de polarité opposée.In the case of the figures, it comprises, for example two stacks la and 1b. Each stack is composed of piezoelectric elements 2, for example plates of piezoelectric ceramic, between which electrodes 3 are inserted. The electrodes 3 are connected alternately on one or the other of two electrical conductors 4a and 4b, of opposite polarity.

Les éléments 2 et les électrodes 3 sont maintenus serrés par une tige centrale de précontrainte 5, d'axe x xl qui est filetée à ses deux extrémités et par deux écrous 6a, 6b qui sont vissés sur les deux extrémités filetées afin de mettre la tige 5 en tension.The elements 2 and the electrodes 3 are held tight by a central prestressing rod 5, of axis x xl which is threaded at its two ends and by two nuts 6a, 6b which are screwed on the two threaded ends in order to put the rod 5 in tension.

Un tel empilement d'éléments piézoélectriques et d'électrodes est bien connu et l'on sait qu'il se déforme parallèlement à l'axe x xl si on applique une tension sinusoidale entre les conducteurs 4a et 4b et que réciproquement, on recueille une tension sinusoidale entre les conducteurs 4a et 4b si le transducteur sert de récepteur d'ondes acoustiques.Such a stack of piezoelectric elements and electrodes is well known and we know that it deforms parallel to the axis x xl if a sinusoidal voltage is applied between the conductors 4a and 4b and that reciprocally, a sinusoidal voltage between conductors 4a and 4b if the transducer serves as a receiver of acoustic waves.

Toutefois l'amplitude des déformations axiales de chaque élément piézoélectrique est limitée par la nature des matériaux Si l'on veut émettre ou capter des ondes acoustiques de trèp fréquence ayant une puissance suffisante, il faut utilise- empilements comportant un très grand nombre d'éléments les transducteurs deviennent très encombrants.However the amplitude of the axial deformation of each piezoelectric element is limited by the nature of the materials If one wants to transmit or receive acoustic TRE p frequency waves having a sufficient power, it is necessary used- stacks comprising a very large number of elements the transducers become very bulky.

Un transducteur immergé selon l'invention permet d'obtenir des grandes amplitudes de déformation du pavillon, c'est-à-dire de la surface active qui est en contact avec l'eau et qui transmet les ondes acoustiques à l'eau dans le cas d'un émetteur ou qui reçoit les ondes acoustiques dans le cas d'un récepteur, et ce résultat est atteint au moyen d'un transducteur dont les dimensions restent relativement réduites, si on les compare à celles qui seraient nécessaires pour obtenir les mêmes amplitudes dans le cas d'un transducteur traditionnel comportant uniquement un empilement d'éléments piézoélectriques.A submerged transducer according to the invention makes it possible to obtain large amplitudes of deformation of the horn, that is to say of the active surface which is in contact with water and which transmits the acoustic waves to the water in the case of a transmitter or which receives the acoustic waves in the case of a receiver, and this result is achieved by means of a transducer whose dimensions remain relatively reduced, if we compare them with those which would be necessary to obtain the same amplitudes in the case of a traditional transducer comprising only a stack of piezoelectric elements.

Un transducteur selon l'invention comporte une plaque de base très rigide 7. Il comporte deux plaques latérales planes 8a et 8b qui sont identiques et perpendiculaires à la plaque de base 7, du même côté de celle-ci. Ces plaques latérales ont, par exemple, une forme rectangulaire. Le bord inférieur de chaque plaque 8a et 8b est relié à la plaque de base, par exemple au moyen de plaques 9a et 9b qui sont composées chacune de deux demi plaques qui sont fixées à la plaque de base 7 par des vis 10 et qui enserrent entre elles le bord inférieur des plaques 8a et 8b. Chaque plaque 8a, 8b comporte, le long de son bord inférieur, immédiatement audessus des plaques 9a et 9b, un amincissement 11, constitué par exemple par deux gorges lla et Ilb, situées de part et d'autre de la plaque de telle sorte que les plaques 8a et 8b puissent se déformer en pivotant autour de l'amincissement 11.A transducer according to the invention comprises a very rigid base plate 7. It comprises two flat side plates 8a and 8b which are identical and perpendicular to the base plate 7, on the same side thereof. These side plates have, for example, a rectangular shape. The lower edge of each plate 8a and 8b is connected to the base plate, for example by means of plates 9a and 9b which are each composed of two half plates which are fixed to the base plate 7 by screws 10 and which enclose between them the lower edge of the plates 8a and 8b. Each plate 8a, 8b comprises, along its lower edge, immediately above the plates 9a and 9b, a thinning 11, constituted for example by two grooves 11a and 11b, situated on either side of the plate so that the plates 8a and 8b can deform by pivoting around the thinning 11.

En d'autre termes, les plaques 8a et 8b sont fixées en console sur la plaque 7 par des semi encastrements.In other words, the plates 8a and 8b are fixed in console on the plate 7 by semi-recesses.

Suivant une variante représentée sur la figure 4, ce semi encastrement peut être remplacé par une articulation autour d'un axe parallèle au bord inférieur de chaque plaque. Dans ce cas, chaque plaque latérale telle que 8a comporte, le long de son bord inférieur, un bourrelet 12 de section circulaire, qui est engagé dans une gorge 13 de section circulaire, creusée dans la plaque de base 7. Deux demi plaques 14a et 14b sont vissées sur la plaque 7 et maintiennent le bourrelet 12 dans son logement tout en lui permettant de pivoter. Bien entendu, cette articulation peut être remplacée par tout autre type d'articulation équivalent.According to a variant shown in FIG. 4, this semi-embedding can be replaced by an articulation around an axis parallel to the lower edge of each plate. In this case, each side plate such as 8a comprises, along its lower edge, a bead 12 of circular section, which is engaged in a groove 13 of circular section, hollowed out in the base plate 7. Two half plates 14a and 14b are screwed onto the plate 7 and maintain the bead 12 in its housing while allowing it to pivot. Of course, this articulation can be replaced by any other equivalent type of articulation.

Les empilements la et 1b s'étendent au-dessus de la plaque de base 7, perpendiculairement aux deux plaques Sa et 8b.The stacks 1a and 1b extend above the base plate 7, perpendicular to the two plates Sa and 8b.

Les deux extrémités axialement opposées de l'empilement 1 sont appuyées contre les faces internes des deux plaques 8a et 8b légèrement au-dessus de l'amincissement 11. L'appui est réalisé au moyen d'une pièce d'appui intermédiaire 15a, 15b. Une pièce d'appui 15 est représentée en perspective sur la figure 5. Cette pièce présente une première face latérale plane 16 qui est appuyée contre une des plaques latérales 8 et une deuxième face latérale 17, opposée à la face 16, qui est appuyée contre une extrémité de l'empilement 1.The two axially opposite ends of the stack 1 are pressed against the internal faces of the two plates 8a and 8b slightly above the thinning 11. The support is produced by means of an intermediate support piece 15a, 15b . A support piece 15 is shown in perspective in FIG. 5. This piece has a first flat side face 16 which is pressed against one of the side plates 8 and a second side face 17, opposite to the face 16, which is pressed against one end of the stack 1.

La face 17 est une portion de surface cylindrique, en arc de cercle, de telle sorte que l'appui de l'empilement sur la face d'appui se fait le long d'une ligne qui est la génératrice médiane 18 de la face 17. Chaque pièce 15 comporte deux trous 19a et 19b pour le passage des prolongements de la tige 5 qui traversent les plaques 8a et 8b. Des écrous 20a et 20b sont vissés sur ces prolongements pour maintenir les empilements la et lb en place.The face 17 is a portion of cylindrical surface, in an arc of a circle, so that the support of the stack on the support face takes place along a line which is the median generatrix 18 of the face 17 Each part 15 has two holes 19a and 19b for the passage of the extensions of the rod 5 which pass through the plates 8a and 8b. Nuts 20a and 20b are screwed onto these extensions to keep the stacks 1a and 1b in place.

La forme cylindrique des faces 17 de la pièce d'appui 15 permet de déterminer avec précision la ligne d'appui 18 et donc la distance qui sépare celle-ci de la ligne autour de laquelle les plaques 8a et 8b peuvent pivoter, c'est-à-dire de l'amincissement 11 ou du centre du bourrelet 12.The cylindrical shape of the faces 17 of the support piece 15 makes it possible to precisely determine the support line 18 and therefore the distance which separates it from the line around which the plates 8a and 8b can pivot, that is ie thinning 11 or the center of the bead 12.

Les plaques 8a et 8b font fonction de leviers dont les amincissements 11 ou les bourrelets 12 constituent le point d'appui, tandis que la distance séparant ce point d'appui 18 constitue le petit bras du levier. Il est précisé que les pièces d'appui 15a et 15b peuvent être inversées, de sorte que leur face cylindrique 17 soit placée au contact d'une plaque latérale 8a ou 8b.The plates 8a and 8b act as levers, the thinning 11 or the beads 12 of which constitute the fulcrum, while the distance separating this fulcrum 18 constitutes the small arm of the lever. It is specified that the support pieces 15a and 15b can be reversed, so that their cylindrical face 17 is placed in contact with a side plate 8a or 8b.

Dans l'exemple représenté sur les figures 1 à 3, chaque empilement la, 1b est composé de deux demi empilements symétriques par rapport à un point fixe central 21 qui est constitué par exemple par une plaque fixée à la plaque de base 7 par des vis 22.In the example shown in FIGS. 1 to 3, each stack 1a, 1b is composed of two half stacks symmetrical with respect to a central fixed point 21 which is constituted for example by a plate fixed to the base plate 7 by screws 22.

Le transducteur représenté sur les figures 1, 2 et 3 comporte, en outre, un pavillon 23 qui est la surface active, en contact acoustique avec l'eau.The transducer shown in Figures 1, 2 and 3 further comprises a horn 23 which is the active surface, in acoustic contact with the water.

Ce pavillon est constitué par une membrane élastique et flexible, par exemple une plaque mince en acier à ressort ayant une épaisseur de quelques millimètres.This pavilion is constituted by an elastic and flexible membrane, for example a thin plate of spring steel having a thickness of a few millimeters.

Cette plaque est fixée par tout moyen le long de chacun de ses deux bords latéraux à un bord supérieur de l'une des plaques latérales 8a et 8b. Par exemple, les deux bords latéraux de la plaque 23 sont repliés pour former des plis 23a et 23b et ces plis sont maintenus pincés entre une plaque 8a ou 8b et une plaque de fixation 24a, 24b fixée à la plaque 8a ou 8b par des vis 25. Des vis 26 vissées dans l'épaisseur des plaques 8a et 8b peuvent renforcer cette fixation.This plate is fixed by any means along each of its two lateral edges to an upper edge of one of the lateral plates 8a and 8b. For example, the two lateral edges of the plate 23 are folded back to form folds 23a and 23b and these folds are held pinched between a plate 8a or 8b and a fixing plate 24a, 24b fixed to the plate 8a or 8b by screws 25. Screws 26 screwed into the thickness of the plates 8a and 8b can reinforce this fixing.

De préférence, la plaque 23 est cintrée, la face convexe étant tournée, de préférence, du côté opposé à la plaque de base 7.Preferably, the plate 23 is curved, the convex face being turned, preferably, on the side opposite to the base plate 7.

Selon un mode de réalisation préférentiel, on utilise une plaque ayant une largeur dans le sens parallèle à l'axe x xl légèrement supérieure à l'écartement entre les deux plaques latérales 8a et 8b et on la comprime légèrement dans le sens parallèle à l'axe x xl avant de la fixer le long des deux bords supérieurs des plaques 8a et 8b.According to a preferred embodiment, a plate is used having a width in the direction parallel to the axis x xl slightly greater than the spacing between the two side plates 8a and 8b and it is slightly compressed in the direction parallel to the axis x xl before fixing it along the two upper edges of the plates 8a and 8b.

Le transducteur selon les figures 1 à 3 comporte un boîtier étanche composé de deux flasques 27a et 27b parallèles aux plaques 8a et 8b et de deux flasques latéraux 28a et 28b, visibles sur la figure 3 et une membrane souple 29, formant une peau d'étanchéité, qui enveloppe les flasques 27a, 27b, 28a, 28b et le pavillon 23.The transducer according to FIGS. 1 to 3 comprises a sealed housing composed of two flanges 27a and 27b parallel to the plates 8a and 8b and of two lateral flanges 28a and 28b, visible in FIG. 3 and a flexible membrane 29, forming a skin of sealing, which envelops the flanges 27a, 27b, 28a, 28b and the roof 23.

La peau 29 est en un matériau ayant une impédance acoustique voisine de celle de l'eau de telle sorte qu'elle est transparente acoustiquement et qu'elle ne perturbe pas la transmission des ondes entre l'eau et la surface active du pavillon 23. Elle est collée sur le pavillon 23, de sorte qu'elle suit les mouvements de celui-ci. La peau 29 est par exemple une peau mince en caoutchouc ou en matière plastique souple. Un faible jeu existe entre, d'une part, les plaques 8a, 8b et le pavillon 23 et d'autre part, les faces latérales 27a, 27b, 28a, 28b du boîtier, de telle sorte que le boîtier ne gêne pas les mouvements du pavillon et des plaques latérales 8a, 8b.The skin 29 is made of a material having an acoustic impedance close to that of water so that it is acoustically transparent and that it does not disturb the transmission of waves between the water and the active surface of the roof 23. It is glued to the pavilion 23, so that it follows the movements thereof. The skin 29 is for example a thin skin of rubber or flexible plastic. A slight clearance exists between, on the one hand, the plates 8a, 8b and the roof 23 and on the other hand, the lateral faces 27a, 27b, 28a, 28b of the housing, so that the housing does not impede movement flag and side plates 8a, 8b.

L'intérieur du boîtier étanche est rempli de gaz. Si le transducteur doit être utilisé en immersion, on maintient ce gaz en équipression avec l'extérieur par exemple au moyen d'une source de gaz comprimé munie d'un détendeur que l'on règle en fonction de la profondeur.The inside of the waterproof case is filled with gas. If the transducer is to be used in immersion, this gas is maintained in equilibrium with the outside, for example by means of a source of compressed gas provided with a regulator which is adjusted as a function of the depth.

En variante, les deux parois 27a et 27b du boîtier peuvent être supprimées et la membrane 29 peut être collée directement sur les deux faces externes 8a et 8b. Dans ce cas, les plaques 8a et 8b constituent des surfaces actives acoustiquement.As a variant, the two walls 27a and 27b of the housing can be eliminated and the membrane 29 can be glued directly to the two external faces 8a and 8b. In this case, the plates 8a and 8b constitute acoustically active surfaces.

Les figures 1 et 3 représentent un connecteur étanche 30 à travers lequel les conducteurs électriques 4a et 4b traversent la paroi 28b.Figures 1 and 3 show a sealed connector 30 through which the electrical conductors 4a and 4b pass through the wall 28b.

Le fonctionnement de ce transducteur est le suivant. Lorsque l'empilement 1 se déforme longitudinalement suivant l'axe x xl. les déformations sont communiquées aux deux leviers 8a et 8b qui se déforment en pivotant autour de leur point d'appui. Les déplacements des extrémités supérieures des leviers 8a et 8b sont multipliés par le rapport entre les deux bras de levier. Les variations d'écartement entre les deux bords supérieurs des deux levier: 8a et 8b produisent des déformations en flexion de la membrane élastique 23. Les déplacements au centre de la membrane dans le sens perpendiculaire à la plaque de base 7 sont supérieurs aux déplacements des extrémités supérieures des deux leviers 8a et 8b.The operation of this transducer is as follows. When the stack 1 deforms longitudinally along the axis x xl. the deformations are communicated to the two levers 8a and 8b which deform by pivoting around their fulcrum. The displacements of the upper ends of the levers 8a and 8b are multiplied by the ratio between the two lever arms. The variations in spacing between the two upper edges of the two lever: 8a and 8b produce flexural deformations of the elastic membrane 23. The displacements at the center of the membrane in the direction perpendicular to the base plate 7 are greater than the displacements of the upper ends of the two levers 8a and 8b.

La figure 6 représente des mesures de la sensibilité SV d'un transducteur selon l'invention en fonction de la fréquence. On rappelle que la sensibilité SV mesurée en décibels correspond à 20 fois le logarithme du rapport entre la pression acoustique mesurée soit en micro bar soit en micro pascal et la tension en volts.FIG. 6 represents measurements of the sensitivity SV of a transducer according to the invention as a function of the frequency. It is recalled that the sensitivity SV measured in decibels corresponds to 20 times the logarithm of the ratio between the acoustic pressure measured either in micro bar or in micro pascal and the voltage in volts.

La figure 6 représente en abscisses une plage de fréquences comprises entre 80 Hz et 180 Hz. En ordonnées, on a représenté à gauche la sensibilité mesurée suivant la référence y bar par volt et à droite suivant la référence y pascal/volt. On obtient un maximum de sensibilité pour une fréquence de résonance de l'ordre de 125 Hz.FIG. 6 shows on the abscissa a frequency range between 80 Hz and 180 Hz. On the ordinate, the sensitivity measured according to the reference y bar per volt is represented on the left and on the right according to the reference y pascal / volt. A maximum sensitivity is obtained for a resonance frequency of the order of 125 Hz.

La figure 7 représente une coupe longitudinale d'une variante de réalisation d'un transducteur selon l'invention.FIG. 7 represents a longitudinal section of an alternative embodiment of a transducer according to the invention.

Celui-ci est composé de deux demi transducteurs qui disposés symétriquement par rapport à une plaque de base 7 aux deux demi transducteurs. Chacun des deux demi transducteurs est identique à celui qui est représenté sur les figures 1, 2 et 3 et les parties homologues à celles de ces figures sont représentées par les mêmes repères. Toutefois, on a représenté sur la figure 7 un mode de réalisation selon la variante dans laquelle les parois latérales 27a et 27b du boîtier sont supprimées et la peau 29 est collée directement sur les pavillons 23 et sur les flasques latéraux 8a et 8b.This consists of two half transducers which are arranged symmetrically with respect to a base plate 7 to the two half transducers. Each of the two half transducers is identical to that which is represented in FIGS. 1, 2 and 3 and the parts homologous to those of these figures are represented by the same references. However, there is shown in Figure 7 an embodiment according to the variant in which the side walls 27a and 27b of the housing are removed and the skin 29 is bonded directly to the pavilions 23 and the side flanges 8a and 8b.

Un avantage de ce mode de réalisation est qu'il permet d'utiliser une plaque de base 7 moins rigide car elle est sollicitée en flexion symétriquement par les deux demi transducteurs. De plus, un transducteur selon la figure 7 est très omnidirectionnel.An advantage of this embodiment is that it makes it possible to use a less rigid base plate 7 because it is bi-symmetrically stressed by the two half transducers. In addition, a transducer according to Figure 7 is very omnidirectional.

La figure 8 représente schématiquement un exemple de réalisation d'une antenne acoustique comportant seize transducteurs selon l'invention, par exemple 25 hydrophones, disposés en réseau suivant cinq lignes LI à L5 et cinq colonnes CI à C5.FIG. 8 schematically represents an exemplary embodiment of an acoustic antenna comprising sixteen transducers according to the invention, for example 25 hydrophones, arranged in a network along five lines LI to L5 and five columns CI to C5.

Chaque transducteur est représenté schématiquement par un carré dont deux côtés opposés sont en trait double et représentent les deux plaques latérales 8a et 8b d'un transducteur.Each transducer is represented diagrammatically by a square of which two opposite sides are in double line and represent the two side plates 8a and 8b of a transducer.

Tous les transducteurs sont fixés sur une même plaque rigide 31 qui sert de plaque de base commune à tous les transducteurs.All the transducers are fixed on the same rigid plate 31 which serves as a common base plate for all the transducers.

La plaque 31 peut être plane, cintrée ou cylindrique selon la forme de l'antenne. On peut disposer deux réseaux de transducteurs symétriquement de part et d'autre de la plaque 31.The plate 31 can be flat, curved or cylindrical depending on the shape of the antenna. Two networks of transducers can be arranged symmetrically on either side of the plate 31.

Bien entendu, sans sortir du cadre de l'invention, les divers éléments constitutifs des transducteurs qui viennent d'être décrits à titre d'exemple pourront être remplacés par des éléments équivalents remplissant les mêmes fonctions.Of course, without departing from the scope of the invention, the various constituent elements of the transducers which have just been described by way of example may be replaced by equivalent elements fulfilling the same functions.

Claims (10)

1 - Transducteur piézoélectrique pour très basses fréquences, caractérisé en ce qu'il comporte : - au moins un empilement d'éléments piézoélectriques ayant deux extrémités axialement opposées ; - deux leviers placés de part et d'autre desdits empilements, de telle sorte que chacune des deux extrémités de chaque empilement s'appuie sur un des deux leviers a proximité du point d'appui de celui-ci ; - et un pavillon constitué par une membrane élastique flexible qui relie entre elles les extrémités des deux leviers. 1 - Piezoelectric transducer for very low frequencies, characterized in that it comprises: - at least one stack of piezoelectric elements having two axially opposite ends; - Two levers placed on either side of said stacks, so that each of the two ends of each stack is supported on one of the two levers near the fulcrum thereof; - And a pavilion constituted by a flexible elastic membrane which connects the ends of the two levers together. 2 - Transducteur piézoélectrique selon la revendication 1, caractérisé en ce qu'il comporte : - une plaque de base rigide ; - deux plaques latérales planes, qui sont situées du même côté de ladite plaque de base et qui sont reliées à celle-ci par un semi-encastrement ou par une articulation le long de l'un de leurs bords ; - au moins un empilement d'éléments piézoélectriques ayant deux extrémités axialement opposées qui sont en contact respectivement avec chacune desdites plaques latérales à proximité du bord de celle-ci qui est relié à la plaque de base ; - un pavillon contitué par une membrane élastique et flexible qui relie entre eux les deux bords des deux plaques latérales qui sont opposés aux deux bords reliés à la plaque de base ; - et un boîtier, rempli de gaz, qui renferme lesdits empilements piézoélectriques et dont ledit pavillon constitue l'une des faces, lequel boîtier est enveloppé de façon étanche par une membrane déformable et transparente acoustiquement qui enveloppe également ledit pavillon. 2 - Piezoelectric transducer according to claim 1, characterized in that it comprises: - a rigid base plate; - two flat side plates, which are located on the same side of said base plate and which are connected to the latter by a semi-embedding or by a joint along one of their edges; - At least one stack of piezoelectric elements having two axially opposite ends which are in contact respectively with each of said side plates near the edge thereof which is connected to the base plate; - a pavilion formed by an elastic and flexible membrane which connects the two edges of the two side plates which are opposite to the two edges connected to the base plate; - And a housing, filled with gas, which contains said piezoelectric stacks and of which said pavilion constitutes one of the faces, which casing is sealed in a sealed manner by a deformable and acoustically transparent membrane which also envelops said pavilion. 3 - Transducteur piézoélectrique selon la revendication 1, caractérisé en ce qu'il comporte : - une plaque de base rigide ; - deux plaques latérales planes qui sont situées du même côté de ladite plaque de base et qui sont reliées à celle-ci par un semi encastrement ou par une articulation le long de l'un d-leurs bords ; - au moins un empilement d'éléments piézoélectriques ayant deux extrémités axialement opposées qui sont en contact respectivement avec chacune desdites plaques latérales à proximité du bord de celle-ci qui est relié à ladite plaque de base ; - un pavillon constitué par une membrane élastique et flexible qui relie entre eux les deux bords des deux plaques latérales qui sont opposés aux deux bords reliés à ladite plaque de base ; - et un boîtier rempli de gaz qui renferme lesdits empilements piézoélectriques et dont ledit pavillon et lesdites plaques latérales constituent des parois, lequel boîtier est enveloppé de façon étanche par une membrane déformable et transparente acoustiquement, laquelle membrane enveloppe ledit pavillon et lesdites plaques latérales. 3 - Piezoelectric transducer according to claim 1, characterized in that it comprises: - a rigid base plate; - two flat side plates which are located on the same side of said base plate and which are connected to the latter by a semi-embedding or by a joint along one of their edges; - At least one stack of piezoelectric elements having two axially opposite ends which are in contact respectively with each of said side plates near the edge thereof which is connected to said base plate; - A pavilion constituted by an elastic and flexible membrane which connects the two edges of the two side plates which are opposite to the two edges connected to said base plate; - And a gas-filled housing which encloses said piezoelectric stacks and of which said pavilion and said side plates constitute walls, which casing is sealed in a sealed manner by a deformable and acoustically transparent membrane, which membrane envelops said pavilion and said side plates. 4 - Transducteur selon l'une quelconque des revendications 1 à 3, caractérisé en ce que lesdits empilements d'éléments piézoélectriques comportent un point fixe central et deux demi- empilements symétriques par rapport audit point fixe.4 - Transducer according to any one of claims 1 to 3, characterized in that said stacks of piezoelectric elements comprise a central fixed point and two half-stacks symmetrical with respect to said fixed point. 5 - Transducteur selon l'une quelconque des revendications 2 à 4, caractérisé en ce qu'il comporte, de part et d'autre de ladite plaque de base, deux transducteurs symétriques par rapport à ladite plaque de base et identiques à un transducteur selon l'une des revendications 2 à 4.5 - Transducer according to any one of claims 2 to 4, characterized in that it comprises, on either side of said base plate, two transducers symmetrical with respect to said base plate and identical to a transducer according one of claims 2 to 4. 6 - Transducteur selon l'une quelconque des revendications 2 à 5, caractérisé en ce que chaque sous-ensemble est composé de deux empilements identiques d'éléments piézoélectriques, parallèles entre eux, ayant chacun un point fixe central relié à ladite plaque de base.6 - A transducer according to any one of claims 2 to 5, characterized in that each sub-assembly is composed of two identical stacks of piezoelectric elements, parallel to each other, each having a central fixed point connected to said base plate. 7 - Transducteur selon l'une quelconque des revendications 1 à 6, caractérisé en ce que ladite membrane élastique et flexible est cintrée.7 - A transducer according to any one of claims 1 to 6, characterized in that said elastic and flexible membrane is curved. 8 - Transducteur selon l'une quelconque des revendications 1 à 6, caractérisé en ce que ladite membrane élastique et flexible est précontrainte en flexion.8 - Transducer according to any one of claims 1 to 6, characterized in that said elastic and flexible membrane is prestressed in bending. 9 - Transducteur selon l'une quelconque des revendications 2 à 8, caractérisé en ce que chaque extrémité desdits empilements d'éléments piézoélectriques est appuyée sur lesdites plaques latérales par l'intermédiaire d'une pièce d'appui intermédiaire ayant une première face latérale plane et une deuxième face latérale, opposée à la première, cylindrique.9 - A transducer according to any one of claims 2 to 8, characterized in that each end of said stacks of piezoelectric elements is supported on said side plates by means of an intermediate support piece having a first flat lateral face and a second lateral face, opposite the first, cylindrical. 10 - Antenne composée de transducteurs selon l'une quelconque des revendications 2 à 9, caractérisée en ce qu'elle comporte une plaque de base commune sur laquelle sont disposées une ou plusieurs rangées et/ou colonnes de transducteurs élémentaires.10 - Antenna composed of transducers according to any one of claims 2 to 9, characterized in that it comprises a common base plate on which are arranged one or more rows and / or columns of elementary transducers.
EP79400291A 1978-05-08 1979-05-08 Piezoelectric transducers with mechanical amplification for very low frequencies and acoustic antennas Expired EP0005409B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7813466 1978-05-08
FR7813466A FR2425785A1 (en) 1978-05-08 1978-05-08 PIEZO-ELECTRIC TRANSDUCERS WITH MECHANICAL AMPLIFICATION FOR VERY LOW FREQUENCIES AND ACOUSTIC ANTENNAS

Publications (3)

Publication Number Publication Date
EP0005409A2 true EP0005409A2 (en) 1979-11-14
EP0005409A3 EP0005409A3 (en) 1979-11-28
EP0005409B1 EP0005409B1 (en) 1981-04-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP79400291A Expired EP0005409B1 (en) 1978-05-08 1979-05-08 Piezoelectric transducers with mechanical amplification for very low frequencies and acoustic antennas

Country Status (4)

Country Link
US (1) US4287582A (en)
EP (1) EP0005409B1 (en)
DE (1) DE2960263D1 (en)
FR (1) FR2425785A1 (en)

Cited By (5)

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EP0243591A2 (en) * 1986-04-30 1987-11-04 AlliedSignal Inc. Underwater transducer
FR2688112A1 (en) * 1988-04-28 1993-09-03 France Etat Armement DIRECTIVE ELECTRO-ACOUSTIC TRANSDUCERS HAVING A SEALED HOUSING INTO TWO PARTS.
US5701277A (en) * 1990-11-28 1997-12-23 Raytheon Company Electro-acoustic transducers
WO2000023822A2 (en) * 1998-10-16 2000-04-27 Western Atlas International, Inc. Slotted cylinder marine seismic method and source
US7591343B2 (en) 2005-08-26 2009-09-22 Halliburton Energy Services, Inc. Apparatuses for generating acoustic waves

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US4709359A (en) * 1982-06-28 1987-11-24 Magnovox Government And Industrial Electronics Company End weighted reed sound transducer
AU578129B2 (en) * 1984-12-19 1988-10-13 Gould Inc. A rare earth flextensional transducer
US4757548A (en) * 1985-12-02 1988-07-12 Fenner Jr Thomas C Speaker system and dome-shaped enclosure therefor
JP2534087B2 (en) * 1986-03-19 1996-09-11 イギリス国 Sonar converter
JPH01501421A (en) * 1986-11-07 1989-05-18 プレッシー　オーストラリア　プロプライエタリー　リミテッド A composite sonar transducer that acts as a low-frequency underwater sound source
US5497357A (en) * 1988-12-23 1996-03-05 Alliedsignal Inc. Shock-resistant flextensional transducer
US5742561A (en) * 1990-05-10 1998-04-21 Northrop Grumman Corporation Transversely driven piston transducer
US5126979A (en) * 1991-10-07 1992-06-30 Westinghouse Electric Corp. Variable reluctance actuated flextension transducer
DE4135408A1 (en) * 1991-10-26 1993-04-29 Man Nutzfahrzeuge Ag Converting electric energy into vibrations - using piezoelectric effect to translate contraction or expansion to vibration of diaphragm
US5406531A (en) * 1993-04-30 1995-04-11 The United States Of America As Represented By The Secretary Of The Navy Low frequency flex-beam underwater acoustic transducer
US6548938B2 (en) 2000-04-18 2003-04-15 Viking Technologies, L.C. Apparatus having a pair of opposing surfaces driven by a piezoelectric actuator
US6717332B2 (en) 2000-04-18 2004-04-06 Viking Technologies, L.C. Apparatus having a support structure and actuator
US6759790B1 (en) * 2001-01-29 2004-07-06 Viking Technologies, L.C. Apparatus for moving folded-back arms having a pair of opposing surfaces in response to an electrical activation
US6879087B2 (en) 2002-02-06 2005-04-12 Viking Technologies, L.C. Apparatus for moving a pair of opposing surfaces in response to an electrical activation
US20030062071A1 (en) * 2001-09-28 2003-04-03 Sorbo Nelson W. Dense-phase fluid cleaning system utilizing ultrasonic transducers
JP4791957B2 (en) 2003-04-04 2011-10-12 バイキング テクノロジィーズ エル．シー． Equipment and methods for optimizing work from functional material actuator products
US20070064539A1 (en) * 2005-08-26 2007-03-22 Wei Han Generating acoustic waves
WO2007023262A1 (en) * 2005-08-26 2007-03-01 Halliburton Energy Services, Inc. Apparatus and methods for generating acoustic waves
US8189851B2 (en) 2009-03-06 2012-05-29 Emo Labs, Inc. Optically clear diaphragm for an acoustic transducer and method for making same
JP6424001B2 (en) * 2010-10-04 2018-11-14 ドクター ヒールシャー ゲーエムベーハー Apparatus and method for clamping an electromechanical composite high frequency vibration system (VFHS)
WO2014143723A2 (en) * 2013-03-15 2014-09-18 Emo Labs, Inc. Acoustic transducers
DE102015212686A1 (en) * 2015-07-07 2017-01-12 Robert Bosch Gmbh transducer
CN107154747B (en) * 2017-06-05 2018-10-30 西安交通大学 A kind of radial piezoelectric actuator based on flexible enlarged structure

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GB123145A (en) * 1918-02-11 1919-02-11 Creed & Co Ltd Improvements in or relating to Means for Amplifying Small Movements, especially applicable for Producing Sounds.
US3258738A (en) * 1963-11-20 1966-06-28 Honeywell Inc Underwater transducer apparatus
US3277433A (en) * 1963-10-17 1966-10-04 William J Toulis Flexural-extensional electromechanical transducer
FR2096795A1 (en) * 1970-06-29 1972-02-25 Whitehall Electronics Corp

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US3614486A (en) * 1969-11-10 1971-10-19 Physics Int Co Lever motion multiplier driven by electroexpansive material
US3649857A (en) * 1970-07-30 1972-03-14 Ibm Mechanical energy storage and release device

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Publication number Priority date Publication date Assignee Title
GB123145A (en) * 1918-02-11 1919-02-11 Creed & Co Ltd Improvements in or relating to Means for Amplifying Small Movements, especially applicable for Producing Sounds.
US3277433A (en) * 1963-10-17 1966-10-04 William J Toulis Flexural-extensional electromechanical transducer
US3258738A (en) * 1963-11-20 1966-06-28 Honeywell Inc Underwater transducer apparatus
FR2096795A1 (en) * 1970-06-29 1972-02-25 Whitehall Electronics Corp

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0243591A2 (en) * 1986-04-30 1987-11-04 AlliedSignal Inc. Underwater transducer
EP0243591A3 (en) * 1986-04-30 1989-01-18 Allied Corporation Underwater transducer
FR2688112A1 (en) * 1988-04-28 1993-09-03 France Etat Armement DIRECTIVE ELECTRO-ACOUSTIC TRANSDUCERS HAVING A SEALED HOUSING INTO TWO PARTS.
US5701277A (en) * 1990-11-28 1997-12-23 Raytheon Company Electro-acoustic transducers
GB2348774A (en) * 1990-11-28 2000-10-11 Raytheon Co Electro-acoustic transducers
GB2348774B (en) * 1990-11-28 2001-02-21 Raytheon Co Electro-acoustic transducers
WO2000023822A2 (en) * 1998-10-16 2000-04-27 Western Atlas International, Inc. Slotted cylinder marine seismic method and source
WO2000023822A3 (en) * 1998-10-16 2000-07-27 Western Atlas Int Inc Slotted cylinder marine seismic method and source
US7591343B2 (en) 2005-08-26 2009-09-22 Halliburton Energy Services, Inc. Apparatuses for generating acoustic waves

Also Published As

Publication number Publication date
EP0005409A3 (en) 1979-11-28
US4287582A (en) 1981-09-01
EP0005409B1 (en) 1981-04-15
DE2960263D1 (en) 1981-05-07
FR2425785B1 (en) 1981-05-29
FR2425785A1 (en) 1979-12-07

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