EP0728534A1 - Transducers with light radiating heads submerged in a fluid and process for emitting low-frequency acoustic waves - Google Patents

Transducers with light radiating heads submerged in a fluid and process for emitting low-frequency acoustic waves Download PDF

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Publication number
EP0728534A1
EP0728534A1 EP96400363A EP96400363A EP0728534A1 EP 0728534 A1 EP0728534 A1 EP 0728534A1 EP 96400363 A EP96400363 A EP 96400363A EP 96400363 A EP96400363 A EP 96400363A EP 0728534 A1 EP0728534 A1 EP 0728534A1
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EP
European Patent Office
Prior art keywords
housing
transducer
cavity
internal
pillar
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Granted
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EP96400363A
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German (de)
French (fr)
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EP0728534B1 (en
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Didier "Le Saint-Michel" - Bât. C Boucher
Yves Ripoll
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Direction General pour lArmement DGA
Etat Francais
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Direction General pour lArmement DGA
Etat Francais
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0611—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile
    • B06B1/0618—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile of piezo- and non-piezoelectric elements, e.g. 'Tonpilz'

Definitions

  • the present invention relates to a method and transducers immersed in a fluid for the emission of low frequency acoustic waves with lightened flags.
  • the technical sector of the invention is that of the production of electroacoustic submersible transducers.
  • the main application and objective of the invention are to be able to either reduce the power consumed by a given submersible transducer composed at least of a horn and a motor pillar to emit waves in a fluid at low frequency , in fact less than 500 Hz, either decrease said frequency range of a given transducer for the same acoustic power, or both at the same time.
  • Such immersible electroacoustic transducers and in particular piezoelectric transducers, are known, comprising a rigid cylindrical housing, hollow and open at its two axial ends, and inside which are arranged coaxially with the latter, two identical electro-acoustic motors, placed on either side of a central counterweight, and the opposite ends of which are surrounded by a flag: these transducers are said to be of the double "Tonpilz" type.
  • Said electro-acoustic motors can be produced by two stacks of aligned piezoelectric plates.
  • the external faces of the two flags are located in the plane of the axial ends of the housing, so that they are in contact with the liquid, in which the housing is immersed, and the external perimeter of these flags comes as close as possible to the edge. open axial ends of said housing.
  • these external faces emit acoustic waves into the liquid when the electro-acoustic motors are electronically excited: these transducers are used in particular to emit low frequency acoustic waves in water in a determined direction; for an application of this type of mono or double "Tonpilz" transducer to high power emissions, mention may be made of the application FR. 2,663,182 by Gilles GROSSO published on December 13, 1991, which describes additional devices to obtain increased power.
  • the electroacoustic efficiency and the power therefore actually emitted which is more and more demanded to date especially in uses where the volume of energy storage is critical, while decreasing the frequency below 500 Hz, it is necessary to decrease the resonant frequencies of the motor and the resonator; the resonant frequency of the motor being that of the transducer separated from the acoustic load of the resonator.
  • the decrease in the resonant frequency of the motor is obtained either by the increase in the mass of the horns, or by the reduction in the ceramic section of the motors (which then weakens them more), which decreases the maximum noise level emitted and is therefore contrary to the objective sought.
  • the problem is therefore to be able to decrease the resonant frequency of the motor of a transducer for a power consumption at most given and / or to increase the acoustic efficiency at low frequency to then also increase the acoustic power without increasing the dimensions and weight.
  • a method of transmitting acoustic waves in a low frequency fluid from a transducer comprising at least one horn attached to the end of a motor pillar, a rigid housing delimiting with said horn a cavity which encloses said motor pillar and having dimensions and a determined external volume, which transducer transmitting waves in a frequency range, at a power and according to a given electroacoustic efficiency: according to the invention, said flag is placed behind inside said housing a dynamic load integral with the latter partially closing its interior section and dividing said interior cavity into two communicating rear and front parts; the peripheral external edge of the pavilions is brought closer to the internal wall of the housing, preferably at a distance of a few tenths of a millimeter; acoustic waves are then emitted at frequencies lower than those of the given initial range and at most with the same initial power consumption given.
  • said transducer thus produced is used in a frequency range surrounding that specific to the rear cavity thus delimited by said dynamic load: the definition and different types of embodiments thereof are described in the presentation of FIG. 1.
  • Figure 1 is an axial sectional view of a transducer of the type indicated above and defined below and equipped with two types of dynamic load according to the invention.
  • FIG. 2 represents comparative acoustic power curves, between a conventional transducer and a transducer of the same type equipped with said dynamic load with respect to the frequency emitted.
  • the present invention can be applied to all types of submersible transducers composed at least of a horn and a motor pillar, even if in the example cited below, it is described, for the sake of simplification of description and the fact that it is a main application of the invention, only horns coupled to electro-acoustic motors of double type transducers "Tonpilz" of cylindrical shape of revolution.
  • the transducer as shown in section in this FIG. 1 therefore comprises, in a known manner, two electro-acoustic motors 1 aligned on an axis xx ', placed on either side of a central counterweight 2 and coaxially with the interior of a cylindrical housing 5, which can be called external covering all of said motors 1 up to the pavilions 3 at the end thereof, the cavity 7, thus delimited by said pavilions and said housing being filled with liquid 4 in which the entire transducer is immersed, such as sea water.
  • Said electro-acoustic motors 1 and the intermediate mass 2 are on the one hand, held together by a prestressing rod 9, also immobilizing by any means of assembly 15 the two pavilions 3 on the ends of the pillar thus formed, and on the other hand, assembled by means of different connecting pieces 11, themselves associated with different fixing pieces 12, some 121 connecting said electro-acoustic motors to the external housing 5 and the others 122 allowing the assembly of the transducer assembly to any external support.
  • the various fixing means are such that they allow freedom of movement of the ends of the electro-acoustic motors on the side of the pavilions 3, which are integral with them and whose peripheral external edge 16, not connected and independent of the internal wall of the housing 5, can then vibrate freely so as to ensure the full emission of acoustic waves in the ambient environment.
  • An inner sleeve 13 isolates the preload rod from said motors 1, and an outer sealing envelope 8 ensures the insulation of these motors 1 and of the pavilions 3 with respect to the ambient medium 4.
  • the power supply of said electro-acoustic motors 1 is supplied by any power cable 10 fixed to said connection parts 11 by an electrical connector 14.
  • the production of such a transducer and all of the various connection parts constituting it are of the field known and achievable by all profession: all the other elements making it possible in particular to obtain the Helmholtz resonance frequency of the cavity as indicated in the introduction, as well as the various connecting elements making it possible to improve the mechanical production of the assembly are not shown here ; some have been the subject of various other patent applications such as those cited in particular in the introduction for so-called compliant tubes.
  • said external housing 5 comprises at least one opening 6 for communication with the outside, said opening possibly consisting of holes distributed around the cylindrical part of the housing or even consisting of a complete circular peripheral opening.
  • said transducer comprises behind each pavilion 3, in this case here the two pavilions shown, and inside the housing 5 a dynamic load 17 associated with each pavilions, integral with said housing 5 and partially closing its internal section by sharing the internal cavity 7 in two parts, rear 71 and front 72, communicating: in the representation of FIG. 1, this corresponds in fact to sharing the whole of the internal cavity of the housing in three cavities, of which only one central rear 71 is median and two so-called "front" cavities 72 are each located behind each of the two flags 3.
  • the dynamic load on the right of the figure consists of a solid wall 23 conforming to the shape of the internal surface of the wall of the housing 5 of which it is integral, surrounding the engine pillar 1 and drilled in less than one orifice 18 through which the latter passes, which orifice carries a conduit 19 extending behind the wall 23 relative to the pavilion 3 and leaving a peripheral passage 20 free around said driving pillar 1.
  • said solid wall 23 includes, as on the right part, an orifice 18 through which passes said driving pillar 1 but with a narrower peripheral passage 20 and comprises in addition various other orifices 21 arranged around said motor pillar 1 and carrying open conduits 22.
  • the walls 23 are fixed at their periphery to the rigid housing 5 by the elements and connecting pieces 12.
  • said walls 23 of the two dynamic loads are located as close as possible to the rear of the roof 3, but they could be located at a greater distance because this is what counts to constitute the additional mass of the fluid to add to that of the pavilions and located in the cavities 72 is above all the ratio of the surfaces of all the conduits 21 and 20 relative to the total section of the housing 5 which corresponds to that of the diameter also of the pavilions 3, and not the mass effective of the fluid located in these cavities 72 and between said pavilion and said dynamic load.
  • the distance "e" between the peripheral external edge 16 of the pavilions 3 and the internal wall of the housing is as small as possible, in any case less than 1 mm and preferably a few tenths of a millimeter , so that this space allows only a small loss of leakage to the liquid from the cavity 72 towards the outside during vibration, so that said fluid stresses above all the dynamic load 17 to thereby virtually increase the mass of the roof 3 and then decrease , at its equal weight and volume, its frequency of emission for the same power consumption.
  • the electroacoustic efficiency is maximum around the resonance frequency of the cavity 71 in fact, the acoustic losses being proportional to the speed flow of the pavilions 3 and of the conduits 21 and 20, these are minimal for these frequencies because the flux participating in the radiation is mainly generated by the openings of the housing 6 which have little loss.
  • this type of transducer must be used around the resonance frequency of the cavity 71.
  • FIG 2 there is shown a curve 24 of acoustic power emission of a transducer as shown in Figure 1 with a dynamic load according to the invention, while curve 25 represents the same transducer but not equipped with said dynamic load, said transmitting powers being noted with respect to frequencies in herz: it is thus noted that in the frequencies below 800 Hz and such that, for example, around the frequency of 500 Hz, the transmitted power is increased in an interesting proportion or vice versa, for a given power, the frequency is reduced by more than 50 Hz.

Abstract

Two (3) horns may be used and their peripheral edge is brought together with the internal wall of the casing (5) making a gap (e) of several tenths of a millimetre. Behind the horn and within the casing is placed a dynamic load (17) partially dividing the space into linked rear (71) and front (72) parts. Waves are emitted in a frequency range below that of the initial given range and at the most with the same initial power consumption. The range of frequencies used is around that belonging to the rear part of the space. The load is a solid wall (23) with a hole (18) for a channel (19) extending away from the horn and leaving a space around the driver (1).

Description

La présente invention a pour objet un procédé et des transducteurs immergés dans un fluide pour l'émission d'ondes acoustiques à basse fréquence avec des pavillons allégés.The present invention relates to a method and transducers immersed in a fluid for the emission of low frequency acoustic waves with lightened flags.

Le secteur technique de l'invention est celui de la réalisation de transducteurs immergeables électroacoustiques.The technical sector of the invention is that of the production of electroacoustic submersible transducers.

L'application principale et l'objectif de l'invention sont de pouvoir, soit réduire la puissance consommée d'un transducteur immergeable donné composé au moins d'un pavillon et d'un pilier moteur pour émettre des ondes dans un fluide en basse fréquence, en fait inférieur à 500 hz, soit diminuer ladite plage de fréquence d'un transducteur donné pour la même puissance acoustique, soit les deux à la fois.The main application and objective of the invention are to be able to either reduce the power consumed by a given submersible transducer composed at least of a horn and a motor pillar to emit waves in a fluid at low frequency , in fact less than 500 Hz, either decrease said frequency range of a given transducer for the same acoustic power, or both at the same time.

On connaît de tels transducteurs électroacoustiques immergeables, et en particulier piézoélectriques, comportant un boîtier cylindrique rigide, creux et ouvert à ses deux extrémités axiales, et à l'intérieur duquel sont disposés coaxialement avec celui-ci, deux moteurs électro-acoustiques identiques, placés de part et d'autre d'une contre-masse centrale, et dont les extrémités opposées sont entourées d'un pavillon : ces transducteurs sont dits de type double "Tonpilz". Lesdits moteurs électro-acoustiques peuvent être réalisés par deux empilements de plaquettes piézo-électriques alignés. Les faces externes des deux pavillons sont situées dans le plan des extrémités axiales du boîtier, de telle sorte qu'elles sont en contact avec le liquide, dans lequel le boîtier est plongé, et le périmètre externe de ces pavillons vient au plus près du bord des extrémités axiales ouvertes dudit boîtier.Such immersible electroacoustic transducers, and in particular piezoelectric transducers, are known, comprising a rigid cylindrical housing, hollow and open at its two axial ends, and inside which are arranged coaxially with the latter, two identical electro-acoustic motors, placed on either side of a central counterweight, and the opposite ends of which are surrounded by a flag: these transducers are said to be of the double "Tonpilz" type. Said electro-acoustic motors can be produced by two stacks of aligned piezoelectric plates. The external faces of the two flags are located in the plane of the axial ends of the housing, so that they are in contact with the liquid, in which the housing is immersed, and the external perimeter of these flags comes as close as possible to the edge. open axial ends of said housing.

Ainsi, ces faces externes émettent dans le liquide des ondes acoustiques lorsque les moteurs électro-acoustiques sont excités électroniquement : ces transducteurs sont utilisés notamment pour émettre dans l'eau des ondes acoustiques basses fréquences dans une direction déterminée; pour une application de ce type de transducteur mono ou double "Tonpilz" à des émissions de fortes puissances, on peut citer la demande FR. 2.663.182 de Monsieur Gilles GROSSO publiée le 13 Décembre 1991, qui décrit des dispositifs complémentaires pour obtenir une puissance accrue.Thus, these external faces emit acoustic waves into the liquid when the electro-acoustic motors are electronically excited: these transducers are used in particular to emit low frequency acoustic waves in water in a determined direction; for an application of this type of mono or double "Tonpilz" transducer to high power emissions, mention may be made of the application FR. 2,663,182 by Gilles GROSSO published on December 13, 1991, which describes additional devices to obtain increased power.

Pour éviter la propagation des ondes acoustiques émises par les faces arrières des pavillons, à l'intérieur du boîtier, surtout quand celui-ci est justement plein de liquide, et qui sont alors retransmises dans le milieu ambiant malgré la rigidité dudit boîtier, on place dans la cavité remplie du liquide ambiant à l'arrière des pavillons de tels boîtiers non étanches, divers moyens tels que des tubes élastiques fermés, étanches et remplis de gaz, et tels que la fréquence de résonance d'Helmholtz de la cavité soit voisine de la fréquence fondamentale des vibrations axiales de l'ensemble vibrant; un tel dispositif est décrit dans la demande de brevet FR. 2.665.998 du 05 Mai 1988 déposée par l'Etat Français Délégué Général pour l'Armement. On reporte ainsi le problème de la résistance à la pression du boîtier extérieur, à la résistance desdits tubes élastiques, qui, étant de diamètres plus faibles, permettent d'avoir un ensemble moins lourd : d'autres moyens peuvent être développés dans le même objectif et s'appliquer à la présente invention, sachant que ces dispositifs nécessitent de conserver une cavité, en arrière des pavillons, de dimensions suffisantes.To avoid the propagation of acoustic waves emitted by the rear faces of the pavilions, inside the housing, especially when it is precisely full of liquid, and which are then retransmitted into the ambient environment despite the rigidity of said housing, are placed in the cavity filled with ambient liquid at the rear of the pavilions of such non-waterproof housings, various means such as closed elastic tubes, sealed and filled with gas, and such that the Helmholtz resonance frequency of the cavity is close to the fundamental frequency of the axial vibrations of the vibrating assembly; such a device is described in the patent application FR. 2.665.998 of 05 May 1988 filed by the French State General Delegate for Armaments. The problem of the resistance to the pressure of the external casing, to the resistance of said elastic tubes, which is therefore of smaller diameters, makes it possible to have a lighter assembly: the other means can be developed with the same objective and apply to the present invention, knowing that these devices require retaining a cavity, behind the pavilions, of sufficient dimensions.

Par ailleurs, quand on veut augmenter, suivant les objectifs de la présente invention, le rendement électroacoustique et la puissance donc réellement émise, ce qui est de plus en plus demandé à ce jour surtout dans des utilisations où le volume de stockage d'énergie est critique, tout en diminuant la fréquence au-dessous de 500 hz, il est nécessaire de diminuer les fréquences de résonance du moteur et du résonateur ; la fréquence de résonance du moteur étant celle du transducteur désolidarisé de la charge acoustique du résonateur. Habituellement la diminution de la fréquence de résonance du moteur s'obtient soit par l'augmentation de la masse des pavillons, soit par la diminution de la section de céramique des moteurs (ce qui alors en plus les fragilise), ce qui en diminue le niveau sonore maximum émis et est donc contraire à l'objectif recherché. Pour pallier cette baisse de puissance, on peut choisir donc plutôt d'augmenter la masse des pavillons et en même temps, d'une part le volume des moteurs électroacoustiques, ce qui se traduit par un allongement de ceux-ci et, d'autre part la rigidité et le coefficient de couplage électromécanique entre les moteurs et les pavillons : cependant, cela oblige alors à augmenter l'encombrement externe du transducteur et son poids, sinon on obtient une conversion de puissance plus faible ; de toute façon, même si la puissance est ainsi augmentée à faible fréquence, le rendement acoustique reste moyen.Furthermore, when it is desired to increase, according to the objectives of the present invention, the electroacoustic efficiency and the power therefore actually emitted, which is more and more demanded to date especially in uses where the volume of energy storage is critical, while decreasing the frequency below 500 Hz, it is necessary to decrease the resonant frequencies of the motor and the resonator; the resonant frequency of the motor being that of the transducer separated from the acoustic load of the resonator. Usually the decrease in the resonant frequency of the motor is obtained either by the increase in the mass of the horns, or by the reduction in the ceramic section of the motors (which then weakens them more), which decreases the maximum noise level emitted and is therefore contrary to the objective sought. To compensate for this drop in power, we can therefore rather choose to increase the mass of the horns and at the same time, on the one hand, the volume of the electroacoustic motors, which results in an elongation of these and, on the other share the rigidity and the electromechanical coupling coefficient between the motors and the pavilions: however, this then requires increasing the external dimensions of the transducer and its weight, otherwise a lower power conversion is obtained; anyway, even if the power is thus increased to low frequency, the acoustic performance remains average.

Le problème posé est donc de pouvoir diminuer la fréquence de résonance du moteur d'un transducteur pour une puissance consommée au plus donné et/ou d'en augmenter le rendement acoustique à basse fréquence pour en augmenter alors également la puissance acoustique sans en augmenter les dimensions et le poids.The problem is therefore to be able to decrease the resonant frequency of the motor of a transducer for a power consumption at most given and / or to increase the acoustic efficiency at low frequency to then also increase the acoustic power without increasing the dimensions and weight.

Une solution au problème posé est un procédé d'émission d'ondes acoustiques dans un fluide à basse fréquence à partir d'un transducteur comportant au moins un pavillon solidaire de l'extrémité d'un pilier moteur, un boîtier rigide délimitant avec ledit pavillon une cavité qui enferme ledit pilier moteur et ayant des dimensions et un volume externe déterminé, lequel transducteur transmettant des ondes dans une plage de fréquence, à une puissance et suivant un rendement électroacoustique donné : selon l'invention, on place en arrière dudit pavillon à l'intérieur dudit boîtier une charge dynamique solidaire de celui-ci fermant partiellement sa section intérieure et partageant ladite cavité intérieure en deux parties arrière et avant communiquant ; on rapproche le bord externe périphérique des pavillons de la paroi interne du boîtier, de préférence à une distance de quelques dixièmes de millimètres ; on émet alors des ondes acoustiques à des fréquences plus basses que celles de la plage initiale donnée et au plus avec la même puissance consommée initiale donnée.One solution to the problem posed is a method of transmitting acoustic waves in a low frequency fluid from a transducer comprising at least one horn attached to the end of a motor pillar, a rigid housing delimiting with said horn a cavity which encloses said motor pillar and having dimensions and a determined external volume, which transducer transmitting waves in a frequency range, at a power and according to a given electroacoustic efficiency: according to the invention, said flag is placed behind inside said housing a dynamic load integral with the latter partially closing its interior section and dividing said interior cavity into two communicating rear and front parts; the peripheral external edge of the pavilions is brought closer to the internal wall of the housing, preferably at a distance of a few tenths of a millimeter; acoustic waves are then emitted at frequencies lower than those of the given initial range and at most with the same initial power consumption given.

De préférence, on utilise ledit transducteur ainsi réalisé dans une plage de fréquence entourant celle propre de la cavité arrière ainsi délimitée par ladite charge dynamique : la définition et différents types de réalisations de celle-ci sont décrites dans la présentation de la figure 1.Preferably, said transducer thus produced is used in a frequency range surrounding that specific to the rear cavity thus delimited by said dynamic load: the definition and different types of embodiments thereof are described in the presentation of FIG. 1.

Le résultat et de nouveaux procédés et transducteurs immergés dans un fluide pour l'émission d'ondes acoustiques à basse fréquence dont on a diminué la fréquence de résonance du moteur sans en augmenter les dimensions ou le poids par rapport à un transducteur donné de même type. En effet, la présence de ladite charge dynamique permet en fait d'augmenter indirectement la masse du pavillon par association d'une masse de liquide située entre celui-ci et ladite charge dynamique ; comme cette dernière ne ferme que partiellement la section intérieure du boîtier, le liquide peut cependant passer de la cavité dite avant vers la cavité dite arrière mais en étant freiné suivant le rapport de surface entre la surface libre du conduit laissé par ladite charge dynamique et la surface totale interne du boîtier : on obtient ainsi une masse virtuelle du pavillon d'autant plus importante que ce rapport de surface est élevé. On peut remarquer également que la nature du matériau constituant ledit pavillon importe peu puisque c'est la masse de liquide que l'on peut additionner à celui-ci qui importe le plus par rapport à sa possibilité de déplacement à travers ladite charge dynamique. Ainsi, on peut considérer qu'un pavillon de l'ordre de 15 kgs en matériau de type aluminium a les mêmes capacités de vibration et donc de puissance acoustique qu'un pavillon de 150 kgs. On peut donc descendre en fréquence en-dessous de 1000 hz et surtout en très basse fréquence jusqu'à 100 ou 200 hz à partir d'un même transducteur, sans avoir à alourdir son pavillon tel que dans les techniques utilisées jusqu'à ce jour. On peut également soit diminuer la puissance nécessaire consommée pour une même puissance d'émission, soit augmenter celle-ci pour une même puissance consommée pour une fréquence donnée tel qu'illustré dans la Figure 2.The result and new processes and transducers immersed in a fluid for the emission of low frequency acoustic waves whose motor resonance frequency has been reduced without increasing its dimensions or weight compared to a given transducer of the same type . In fact, the presence of said dynamic load makes it possible in fact to indirectly increase the mass of the roof by association of a mass of liquid situated between the latter and said dynamic load; as the latter only partially closes the interior section of the housing, the liquid can however pass from the so-called front cavity towards the so-called rear cavity but being braked according to the surface ratio between the free surface of the conduit left by said dynamic load and the total internal surface of the housing: this gives a virtual mass of the roof even more important than this area ratio is high. It can also be noted that the nature of the material constituting said pavilion does not matter since it is the mass of liquid that can be added to it which matters most compared to its possibility of movement through said dynamic load. Thus, we can consider that a pavilion of the order of 15 kg in aluminum type material has the same vibration and therefore acoustic power capacities as a pavilion of 150 kg. We can therefore descend in frequency below 1000 Hz and especially in very low frequency up to 100 or 200 Hz from the same transducer, without having to increase its flag as in the techniques used to date . It is also possible either to decrease the necessary power consumed for the same transmission power, or to increase it for the same power consumed for a given frequency as illustrated in FIG. 2.

On pourrait citer d'autres avantages de la présente invention mais ceux cités ci-dessus en montrent déjà suffisamment pour en prouver la nouveauté et l'intérêt. La description et les figures ci-après représentent un exemple de réalisation de l'invention mais n'ont aucun caractère limitatif : d'autres réalisations sont possibles dans le cadre de la portée de l'étendue de cette invention, en particulier en changeant la forme de la charge dynamique telle que représentée à titre d'exemple dans la Figure 1.We could cite other advantages of the present invention but those mentioned above already show enough to prove its novelty and interest. The description and the figures below represent an exemplary embodiment of the invention but are in no way limiting: other embodiments are possible within the scope of the scope of this invention, in particular by changing the shape of the dynamic load as shown by way of example in Figure 1.

La Figure 1 est une vue en coupe axiale d'un transducteur de type indiqué précédemment et défini ci-après et équipé de deux types de charge dynamique suivant l'invention.Figure 1 is an axial sectional view of a transducer of the type indicated above and defined below and equipped with two types of dynamic load according to the invention.

La Figure 2 représente des courbes comparatives de puissance acoustique, entre un transducteur classique et un transducteur de même type équipé de ladite charge dynamique par rapport à la fréquence émise.FIG. 2 represents comparative acoustic power curves, between a conventional transducer and a transducer of the same type equipped with said dynamic load with respect to the frequency emitted.

Nous notons tout d'abord que la présente invention peut s'appliquer à tous types de transducteurs immergeables composés au moins d'un pavillon et d'un pilier moteur, même si dans l'exemple cité ci-dessous, il n'est décrit, pour des questions de simplification de description et du fait qu'il s'agit d'une application principale de l'invention, que des pavillons couplés à des moteurs électro-acoustiques de transducteurs type double "Tonpilz" de forme cylindrique de révolution.We note first of all that the present invention can be applied to all types of submersible transducers composed at least of a horn and a motor pillar, even if in the example cited below, it is described, for the sake of simplification of description and the fact that it is a main application of the invention, only horns coupled to electro-acoustic motors of double type transducers "Tonpilz" of cylindrical shape of revolution.

Le transducteur tel que représenté en coupe sur cette figure 1 comporte donc d'une manière connue, deux moteurs 1 électro-acoustiques alignés sur un axe xx', placés de part et d'autre d'une contre-masse centrale 2 et coaxialement à l'intérieur d'un boîtier 5 cylindrique, que l'on peut appeler externe recouvrant l'ensemble desdits moteurs 1 jusqu'aux pavillons 3 d'extrémité de ceux-ci, la cavité 7, ainsi délimitée par lesdits pavillons et ledit boîtier étant rempli du liquide 4 dans lequel l'ensemble du transducteur est immergé, tel que l'eau de mer.The transducer as shown in section in this FIG. 1 therefore comprises, in a known manner, two electro-acoustic motors 1 aligned on an axis xx ', placed on either side of a central counterweight 2 and coaxially with the interior of a cylindrical housing 5, which can be called external covering all of said motors 1 up to the pavilions 3 at the end thereof, the cavity 7, thus delimited by said pavilions and said housing being filled with liquid 4 in which the entire transducer is immersed, such as sea water.

Lesdits moteurs électro-acoustiques 1 et la masse intermédiaire 2 sont d'une part, tenus ensemble par une tige de précontrainte 9, immobilisant également par tout moyen d'assemblage 15 les deux pavillons 3 sur les extrémités du pilier ainsi constitués, et d'autre part, assemblés grâce à différentes pièces de liaison 11, associées elles-mêmes à différentes pièces de fixation 12, les unes 121 reliant lesdits moteurs électro-acoustiques au boîtier externe 5 et les autres 122 permettant la fixation de l'ensemble du transducteur sur tout support externe. Les divers moyens de fixation sont tels qu'ils permettent une liberté de déplacement des extrémités des moteurs électro-acoustiques du côté des pavillons 3, qui leur sont solidaires et dont le bord externe périphérique 16, non relié et indépendant de la paroi interne du boîtier 5, peut alors vibrer librement de façon à assurer la pleine émission d'ondes acoustiques dans le milieu ambiant.Said electro-acoustic motors 1 and the intermediate mass 2 are on the one hand, held together by a prestressing rod 9, also immobilizing by any means of assembly 15 the two pavilions 3 on the ends of the pillar thus formed, and on the other hand, assembled by means of different connecting pieces 11, themselves associated with different fixing pieces 12, some 121 connecting said electro-acoustic motors to the external housing 5 and the others 122 allowing the assembly of the transducer assembly to any external support. The various fixing means are such that they allow freedom of movement of the ends of the electro-acoustic motors on the side of the pavilions 3, which are integral with them and whose peripheral external edge 16, not connected and independent of the internal wall of the housing 5, can then vibrate freely so as to ensure the full emission of acoustic waves in the ambient environment.

Un fourreau intérieur 13 isole la tige de précontrainte desdits moteurs 1, et une enveloppe d'étanchéité extérieure 8 assure l'isolation de ces moteurs 1 et des pavillons 3 par rapport au milieu ambiant 4.An inner sleeve 13 isolates the preload rod from said motors 1, and an outer sealing envelope 8 ensures the insulation of these motors 1 and of the pavilions 3 with respect to the ambient medium 4.

L'alimentation desdits moteurs électro-acoustiques 1 est fournie par tout câble d'alimentation 10 fixé sur lesdites pièces de liaison 11 par un connecteur électrique 14. La réalisation d'un tel transducteur et l'ensemble des différentes pièces de liaison le constituant sont du domaine connu et réalisables par tout homme du métier : tous les autres éléments permettant en particulier d'obtenir la fréquence de résonance d'Helmholtz de la cavité telle qu'indiquée en introduction, ainsi que les différents éléments de liaison permettant d'améliorer la réalisation mécanique de l'ensemble sont non figurés ici ; certains ont fait l'objet de diverses autres demandes de brevets comme celles en particulier citées en introduction pour des tubes dits compliants.The power supply of said electro-acoustic motors 1 is supplied by any power cable 10 fixed to said connection parts 11 by an electrical connector 14. The production of such a transducer and all of the various connection parts constituting it are of the field known and achievable by all profession: all the other elements making it possible in particular to obtain the Helmholtz resonance frequency of the cavity as indicated in the introduction, as well as the various connecting elements making it possible to improve the mechanical production of the assembly are not shown here ; some have been the subject of various other patent applications such as those cited in particular in the introduction for so-called compliant tubes.

Pour permettre le remplissage de la cavité 7 par ledit liquide 4, ledit boîtier externe 5 comporte au moins une ouverture 6 de communication avec l'extérieur, ladite ouverture pouvant être constituée de trous répartis autour de la partie cylindrique du boîtier ou même constituée d'une ouverture périphérique circulaire complète.To allow the filling of the cavity 7 with said liquid 4, said external housing 5 comprises at least one opening 6 for communication with the outside, said opening possibly consisting of holes distributed around the cylindrical part of the housing or even consisting of a complete circular peripheral opening.

Suivant la présente invention, ledit transducteur, tel que représenté sur la Figure 1, comporte en arrière de chaque pavillon 3, soit en l'occurence ici des deux pavillons représentés, et à l'intérieur du boîtier 5 une charge dynamique 17 associée à chacun des pavillons, solidaire dudit boîtier 5 et fermant partiellement sa section intérieure en partageant la cavité interne 7 en deux parties, arrière 71 et avant 72, communiquant : dans la représentation de la Figure 1, cela correspond en fait à partager l'ensemble de la cavité interne du boîtier en trois cavités, dont une seule centrale arrière 71 est médiane et deux cavités dites "avant" 72 sont situées chacune derrière chacun des deux pavillons 3.According to the present invention, said transducer, as shown in Figure 1, comprises behind each pavilion 3, in this case here the two pavilions shown, and inside the housing 5 a dynamic load 17 associated with each pavilions, integral with said housing 5 and partially closing its internal section by sharing the internal cavity 7 in two parts, rear 71 and front 72, communicating: in the representation of FIG. 1, this corresponds in fact to sharing the whole of the internal cavity of the housing in three cavities, of which only one central rear 71 is median and two so-called "front" cavities 72 are each located behind each of the two flags 3.

Suivant la représentation de la charge dynamique à droite de la figure, celle-ci est constituée d'une paroi pleine 23 épousant la forme de la surface interne de la paroi du boîtier 5 dont elle est solidaire, entourant le pilier moteur 1 et percé au moins d'un orifice 18 au travers duquel passe celui-ci, lequel orifice porte un conduit 19 s'étendant en arrière de la paroi 23 par rapport au pavillon 3 et laissant un passage périphérique 20 libre autour dudit pilier moteur 1.According to the representation of the dynamic load on the right of the figure, it consists of a solid wall 23 conforming to the shape of the internal surface of the wall of the housing 5 of which it is integral, surrounding the engine pillar 1 and drilled in less than one orifice 18 through which the latter passes, which orifice carries a conduit 19 extending behind the wall 23 relative to the pavilion 3 and leaving a peripheral passage 20 free around said driving pillar 1.

Suivant la représentation de la charge dynamique 17 sur la partie de la figure située à gauche, ladite paroi pleine 23 comporte comme sur la partie droite un orifice 18 au travers duquel passe ledit pilier moteur 1 mais d'un passage périphérique 20 plus étroit et comporte en plus divers autres orifices 21 disposés autour dudit pilier moteur 1 et portant des conduits 22 ouverts. Dans tous les cas, les parois 23 sont fixées à leur périphérie au boîtier rigide 5 par les éléments et pièces de liaison 12.According to the representation of the dynamic load 17 on the part of the figure located on the left, said solid wall 23 includes, as on the right part, an orifice 18 through which passes said driving pillar 1 but with a narrower peripheral passage 20 and comprises in addition various other orifices 21 arranged around said motor pillar 1 and carrying open conduits 22. In all cases, the walls 23 are fixed at their periphery to the rigid housing 5 by the elements and connecting pieces 12.

Tel que représenté sur la Figure 1, lesdites parois 23 des deux charges dynamiques sont situées au plus proche de l'arrière du pavillon 3, mais elles pourraient être situées à une distance plus importante car ce qui compte pour constituer la masse additionnelle du fluide à rajouter à celle des pavillons et situé dans les cavités 72 est surtout le rapport des surfaces de l'ensemble des conduits 21 et 20 par rapport à la section totale du boîtier 5 qui correspond à celle du diamètre également des pavillons 3, et non la masse effective du fluide situé dans ces cavités 72 et compris entre ledit pavillon et ladite charge dynamique.As shown in Figure 1, said walls 23 of the two dynamic loads are located as close as possible to the rear of the roof 3, but they could be located at a greater distance because this is what counts to constitute the additional mass of the fluid to add to that of the pavilions and located in the cavities 72 is above all the ratio of the surfaces of all the conduits 21 and 20 relative to the total section of the housing 5 which corresponds to that of the diameter also of the pavilions 3, and not the mass effective of the fluid located in these cavities 72 and between said pavilion and said dynamic load.

Par contre, il est nécessaire que la distance "e" entre le bord externe périphérique 16 des pavillons 3 et la paroi interne du boîtier soit la plus réduite possible, de toute façon de moins d'l mm et de préférence de quelques dixièmes de millimètres, afin que cet espace ne permette que peu de perte de fuite àu liquide de la cavité 72 vers l'extérieur en cours de vibration, afin que cedit fluide sollicite surtout la charge dynamique 17 pour augmenter ainsi virtuellement la masse du pavillon 3 et diminuer alors, à poids et volume égaux de celui-ci, sa fréquence d'émission pour une même puissance consommée.On the other hand, it is necessary that the distance "e" between the peripheral external edge 16 of the pavilions 3 and the internal wall of the housing is as small as possible, in any case less than 1 mm and preferably a few tenths of a millimeter , so that this space allows only a small loss of leakage to the liquid from the cavity 72 towards the outside during vibration, so that said fluid stresses above all the dynamic load 17 to thereby virtually increase the mass of the roof 3 and then decrease , at its equal weight and volume, its frequency of emission for the same power consumption.

De plus, le rendement électroacoustique est maximal autour de la fréquence de résonance de la cavité 71 en effet, les pertes acoustiques étant proportionnelles au flux de vitesse des pavillons 3 et des conduits 21 et 20, celles ci sont minimales pour ces fréquences car le flux participant au rayonnement est principalement généré par les ouvertures du boîtier 6 qui ne présentent que peu de perte. Ainsi, pour des applications nécessitant un rendement électroacoustique élevé, il faut utiliser ce type de transducteur autour de la fréquence de résonance de la cavité 71.In addition, the electroacoustic efficiency is maximum around the resonance frequency of the cavity 71 in fact, the acoustic losses being proportional to the speed flow of the pavilions 3 and of the conduits 21 and 20, these are minimal for these frequencies because the flux participating in the radiation is mainly generated by the openings of the housing 6 which have little loss. Thus, for applications requiring a high electroacoustic efficiency, this type of transducer must be used around the resonance frequency of the cavity 71.

Sur la Figure 2, il est représenté une courbe 24 d'émission de puissance acoustique d'un transducteur tel que représenté sur la Figure 1 avec une charge dynamique suivant l'invention, alors que la courbe 25 représente le même transducteur mais non équipé de ladite charge dynamique, lesdites puissances d'émission étant relevées par rapport aux fréquences en herz : on note ainsi que dans les fréquences en-dessous de 800 hz et telles que, par exemple, autour de la fréquence de 500 hz, on augmente dans une proportion intéressante la puissance émise ou inversement, pour une puissance donnée, on diminue la fréquence de plus de 50 hz. Ceci a été bien sur mesuré à partir d'un type de transducteur donné, mais avec d'autres transducteurs, on peut obtenir un gain encore plus important, baisser encore plus la fréquence d'émission et/ou les deux à la fois, sans alourdir les pavillons du transducteur donné.In Figure 2, there is shown a curve 24 of acoustic power emission of a transducer as shown in Figure 1 with a dynamic load according to the invention, while curve 25 represents the same transducer but not equipped with said dynamic load, said transmitting powers being noted with respect to frequencies in herz: it is thus noted that in the frequencies below 800 Hz and such that, for example, around the frequency of 500 Hz, the transmitted power is increased in an interesting proportion or vice versa, for a given power, the frequency is reduced by more than 50 Hz. This was of course measured from a given type of transducer, but with other transducers, we can obtain an even greater gain, lower the emission frequency even more and / or both at the same time, without increase the pavilions of the given transducer.

Claims (9)

Procédé d'émission d'ondes acoustiques dans un fluide (4) à basse fréquence à partir d'un transducteur comportant au moins un pavillon (3) solidaire de l'extrémité d'un pilier moteur (1), un boîtier rigide (5) délimitant avec ledit pavillon une cavité (7) qui enferme ledit pilier moteur et ayant des dimensions et un volume externe déterminé, lequel transducteur transmettant des ondes dans une plage de fréquence, à une puissance et suivant un rendement électroacoustique donné, caractérisé en ce que : - on place en arrière dudit pavillon (3) à l'intérieur dudit boîtier (5) une charge dynamique (17) solidaire de celui-ci fermant partiellement sa section intérieure et partageant ladite cavité intérieure (7) en deux parties arrière (71) et avant (72) communiquant; - on rapproche le bord externe périphérique (16) des pavillons (3) de la paroi interne du boîtier (5) ; - on émet des ondes acoustiques à des fréquences plus basses que celles de la plage initiale donnée et au plus avec la même puissance consommée initiale donnée. Method for transmitting acoustic waves in a fluid (4) at low frequency from a transducer comprising at least one horn (3) integral with the end of a driving pillar (1), a rigid housing (5 ) delimiting with said flag a cavity (7) which encloses said motor pillar and having dimensions and a determined external volume, which transducer transmitting waves in a frequency range, at a power and according to a given electroacoustic efficiency, characterized in that : - placing behind said roof (3) inside said housing (5) a dynamic load (17) integral with the latter partially closing its internal section and dividing said internal cavity (7) in two rear parts (71) and before (72) communicating; - The peripheral external edge (16) of the pavilions (3) is brought closer to the internal wall of the housing (5); - acoustic waves are emitted at frequencies lower than those of the initial range given and at most with the same initial power consumption given. Procédé d'émission d'ondes acoustiques suivant la revendication 1, caractérisé en ce qu'on rapproche au maximum le bord externe périphérique (16) du pavillon (3) de la paroi interne du boîtier (5) pour réduire l'espace "e" ainsi délimité à quelques dixièmes de millimètre.Acoustic wave emission method according to claim 1, characterized in that the peripheral external edge (16) of the roof (3) is brought as close as possible to the internal wall of the housing (5) to reduce the space "e "thus delimited to a few tenths of a millimeter. Procédé d'émission d'ondes acoustiques selon l'une quelconque des revendications 1 ou 2, caractérisé en ce qu'on utilise ledit transducteur ainsi réalisé dans une plage de fréquence entourant celle propre de la cavité arrière (71).Acoustic wave emission method according to any one of claims 1 or 2, characterized in that said transducer thus produced is used in a frequency range surrounding that of the rear cavity (71). Transducteur immergeable dans un fluide (4) pour l'émission d'ondes acoustiques à basse fréquence comportant au moins un pavillon (3) solidaire de l'extrémité d'un pilier moteur (1), un boîtier rigide (5) délimitant avec ledit pavillon une cavité (7) qui enferme ledit pilier moteur, et ayant des dimensions et un volume externe déterminés, lequel transducteur transmettant des ondes dans une plage de fréquence, à une puissance et suivant un rendement électroacoustique donné, caractérisé en ce que il comporte en arrière dudit pavillon (3) et à l'intérieur du boîtier (5) une charge dynamique (17) solidaire de celui-ci fermant partiellement sa section intérieure et partageant la cavité interne (7) en deux parties arrière (71) et avant (72) communiquant.Transducer submersible in a fluid (4) for the emission of low frequency acoustic waves comprising at least one horn (3) integral with the end of a motor pillar (1), a rigid housing (5) delimiting with said flag a cavity (7) which encloses said motor pillar, and having determined dimensions and external volume, which transducer transmitting waves in a frequency range, at a power and according to a given electroacoustic efficiency, characterized in that it comprises in rear of said roof (3) and inside the housing (5) a load dynamic (17) integral with the latter partially closing its internal section and dividing the internal cavity (7) into two communicating rear (71) and front (72) parts. Transducteur suivant la revendication 4, caractérisé en ce que la distance "e" séparant le bord externe périphérique (16) des pavillons (3) et la paroi interne du boîtier (5) est de moins de 1 mm.Transducer according to claim 4, characterized in that the distance "e" separating the peripheral external edge (16) of the pavilions (3) and the internal wall of the housing (5) is less than 1 mm. Transducteur selon l'une quelconque des revendications 4 à 5, caractérisé en ce que ladite charge dynamique (17) est constituée d'une paroi pleine (23) épousant la forme de la surface interne du boîtier (5) dont elle est solidaire, entourant le pilier moteur (1) et percé au moins d'un orifice (18) au travers duquel passe celui-ci, lequel orifice porte un conduit (19) s'étendant en arrière de la paroi (23) par rapport au pavillon (3) et laissant un passage périphérique (20) libre autour dudit pilier moteur (1).Transducer according to any one of claims 4 to 5, characterized in that said dynamic load (17) consists of a solid wall (23) matching the shape of the internal surface of the housing (5) of which it is integral, surrounding the driving pillar (1) and pierced with at least one orifice (18) through which the latter passes, which orifice carries a conduit (19) extending behind the wall (23) relative to the pavilion (3 ) and leaving a peripheral passage (20) free around said driving pillar (1). Transducteur suivant la revendication 6, caractérisé en ce que ladite paroi pleine (23) comporte différents orifices (21) disposés autour dudit pilier moteur (1) et portant des conduits (22) ouverts.Transducer according to claim 6, characterized in that said solid wall (23) comprises different orifices (21) arranged around said driving pillar (1) and carrying open conduits (22). Transducteur selon l'une quelconque des revendications 6 et 7, caractérisé en ce que ladite paroi (23) est située au plus proche de l'arrière du pavillon (3).Transducer according to either of Claims 6 and 7, characterized in that the said wall (23) is located closest to the rear of the roof (3). Transducteur selon l'une quelconque des revendications 4 à 8, caractérisé en ce que ledit boîtier (5) est cylindrique et enferme deux moteurs électroacoustiques identiques (1) placés de part et d'autre d'une contremasse centrale (2) et dont les extrémités opposées sont entourées chacune d'un pavillon (3) associé à une charge dynamique (17).Transducer according to any one of claims 4 to 8, characterized in that said housing (5) is cylindrical and encloses two identical electroacoustic motors (1) placed on either side of a central countermass (2) and whose opposite ends are each surrounded by a pavilion (3) associated with a dynamic load (17).
EP96400363A 1995-02-23 1996-02-22 Transducers with light radiating heads submerged in a fluid and process for emitting low-frequency acoustic waves Expired - Lifetime EP0728534B1 (en)

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FR9502092 1995-02-23
FR9502092A FR2731128B1 (en) 1995-02-23 1995-02-23 METHOD AND TRANSDUCERS UNDERGROUND IN A FLUID FOR THE TRANSMISSION OF LOW FREQUENCY ACOUSTIC WAVES WITH LIGHT PAVILIONS

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EP0728534A1 true EP0728534A1 (en) 1996-08-28
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FR2818754B1 (en) * 2000-12-21 2004-06-18 Inst Francais Du Petrole DEVICE FOR GENERATING FOCUSED ELASTIC WAVES IN A MATERIAL MEDIUM SUCH AS THE BASEMENT, AND METHOD FOR ITS IMPLEMENTATION
IL157871A (en) 2003-09-11 2008-08-07 Aharon Bornstein Non-lethal land mines

Citations (3)

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Publication number Priority date Publication date Assignee Title
EP0462037A1 (en) * 1990-06-12 1991-12-18 Gilles A . Grosso Underwater electro-acoustic transducer
FR2665998A1 (en) * 1988-05-05 1992-02-21 France Etat Armement ELECTRO ACOUSTIC METHODS AND TRANSDUCERS FOR TRANSMITTING LOW FREQUENCY ACOUSTIC WAVES IN A LIQUID
EP0596763A1 (en) * 1992-11-05 1994-05-11 ETAT-FRANCAIS représenté par le DELEGUE GENERAL POUR L'ARMEMENT (DPAG) Process and transducer for emitting low-frequency acoustic waves immersed without restriction in a liquid

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FR596763A (en) * 1924-07-22 1925-10-31 Product for cleaning windows, mirrors, marble, etc.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2665998A1 (en) * 1988-05-05 1992-02-21 France Etat Armement ELECTRO ACOUSTIC METHODS AND TRANSDUCERS FOR TRANSMITTING LOW FREQUENCY ACOUSTIC WAVES IN A LIQUID
EP0462037A1 (en) * 1990-06-12 1991-12-18 Gilles A . Grosso Underwater electro-acoustic transducer
EP0596763A1 (en) * 1992-11-05 1994-05-11 ETAT-FRANCAIS représenté par le DELEGUE GENERAL POUR L'ARMEMENT (DPAG) Process and transducer for emitting low-frequency acoustic waves immersed without restriction in a liquid

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FR2731128B1 (en) 1997-04-11
US5636183A (en) 1997-06-03
DE69600159T2 (en) 1998-08-20
FR2731128A1 (en) 1996-08-30
CA2170091A1 (en) 1996-08-24
DE69600159D1 (en) 1998-03-12

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