EP0762381A1 - Transducteur électroacoustique flextenseur - Google Patents

Transducteur électroacoustique flextenseur Download PDF

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Publication number
EP0762381A1
EP0762381A1 EP96401885A EP96401885A EP0762381A1 EP 0762381 A1 EP0762381 A1 EP 0762381A1 EP 96401885 A EP96401885 A EP 96401885A EP 96401885 A EP96401885 A EP 96401885A EP 0762381 A1 EP0762381 A1 EP 0762381A1
Authority
EP
European Patent Office
Prior art keywords
shell
rings
transducer
transducer according
tapes
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.)
Ceased
Application number
EP96401885A
Other languages
German (de)
English (en)
French (fr)
Inventor
Eric Sernit
Robert Fichaux
Gilbert Roman
Yves Lagier
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.)
Thales SA
Original Assignee
Thomson CSF SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0762381A1 publication Critical patent/EP0762381A1/fr
Ceased legal-status Critical Current

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Classifications

    • 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 present invention relates to electroacoustic flexural transducers in which the emitting part is formed by a bent shell which is vibrated by a motor, of the piezoelectric type for example. These transducers are used to emit acoustic waves, in the sound domain for example, within waters, in particular to detect other boats by a sonar type tracking system.
  • flexural transducers are known, known more particularly under the Anglo-Saxon name “barrel stave”, which are in the form of a barrel with a concave profile instead of being convex.
  • Such a transducer is for example described in US Pat. No. 4,922,470.
  • the embodiment which is described in this patent comprises a set of internally curved panels which are machined separately and mounted on flanges of polygonal ends with screws.
  • the piezoelectric motor extends between these two flanges to set them in motion and consequently excite the walls of the constricted hollow body formed by the panels and the flanges.
  • An external rubber wall provides the necessary seal for this body.
  • Longitudinal threaded rods extending between the two flanges make it possible to prestress the piezoelectric motor.
  • the construction of such a device is particularly complicated and the device obtained has many drawbacks. More particularly, the tolerances on the mechanical dimensions do not make it possible to obtain sufficient reproducibility of the performances and the sealing under immersion is far from being guaranteed. In addition, the cost of such a complex system is significant.
  • the invention provides a flexuring transducer, of the type comprising a cylinder-shaped shell shrunk in its central part and provided with longitudinal slots extending along this constricted part, a motor formed of superimposed piezoelectric rings. and placed inside the shell along the axis thereof, tapes to close the shell, and an elastic envelope to seal the shell, mainly characterized in that the ends of the shell and the tapes are threaded to be assembled by screwing in order to prestress said motor, and in that the envelope forms an overmolded skin on the outside of said shell and having at the level of the longitudinal slots hollow grooves intended to prevent the overmolded skin from creep into said slots under the effect of immersion pressure.
  • the transducer comprises junction pieces with a diameter greater than that of the piezoelectric rings, placed at the two ends of the stack of rings so as to fit into the internal shoulders situated at the two ends of the shell in order to center the engine inside this hull.
  • the transducer further comprises prestressing rings placed between the end pieces and the tapes and threaded to be screwed into the threaded ends of the shell in order to obtain a precise value of the prestressing applied to the motor. .
  • the piezoelectric rings comprise longitudinal lateral notches making it possible to pass the connection wires of the excitation electrodes of these rings, without these connection wires extending beyond the external diameter of the rings.
  • the longitudinal slots are of variable width to optimize the operation of the transducer as a function of the immersion.
  • the tapes have a part which projects outside the ends of the shell; this overflowing part being machined in the shape of a ball joint to allow the transducers to be assembled one after the other using junction pieces adapted to these ball joints.
  • the longitudinal slots are filled with a very soft plastic material.
  • the transducer according to the invention shown in exploded and simplified view in FIG. 1, and in assembled section and more detailed in FIG. 2, comprises a shell 101, made of titanium for example, having the general shape of a tube shrunk in its central part and therefore roughly shaped like a child's toy known as a "diabolo".
  • This narrowed central part is thin and the two ends are thicker and have inside a shoulder 102 surmounted by a threaded part 103.
  • This shell will for example be machined in a solid bar to obtain the different shapes and thicknesses desired. If necessary to facilitate manufacture, it is possible to start from a tube whose ends will be forged to obtain the extra thicknesses necessary for the shoulder and the thread, and the central part of which will be constricted.
  • This shell comprises on its central portion constricted longitudinal slots 104, 6 for example, regularly distributed over the periphery of the shell. These slots provide sufficient flexibility and regular contraction of the shell under the effect of immersion. They are obtained for example by milling and their width is constant when the pressure is not applied.
  • the outer wall of the shell is covered by overmolding with a sealing envelope 105, or skin, in polyurethane for example.
  • an excitation motor is placed formed by a stack of piezoelectric ceramic rings 106 separated by electrodes 107. These electrodes are joined, in a known alternating manner, by connection wires 108 which make it possible to apply the excitation voltages necessary to the ceramic rings.
  • the two ends of this stack are terminated by joining pieces 109 whose diameter is larger than the ceramic rings and which are housed exactly on the shoulders 102 to keep the engine centered in the middle of the hull.
  • the diameter of the ceramic rings is chosen so that at maximum immersion, the shell 101, contracted under the effect of pressure, does not touch these rings.
  • the parts 109 have at the junction with the ceramic rings a chamfer 110, not shown in Figure 1, which allows to distribute the prestressing pressure applied to the rings by these parts.
  • the invention proposes to provide, as shown in FIG. 3, on the lateral faces of the stack of rings two grooves 111 which allow to pass the connection wires 108.
  • connection wires 108 have been formed on the lateral junction face between the rings and one or the other, or both, junction pieces 109, which then allow the connection wires 108 to penetrate inside. from the central hole 112 of the stack of rings, so that these connection wires can come out of the assembled transducer.
  • end screws 113 are screwed to the two ends of this hull. threaded to the pitch of the internal thread 103.
  • these tapes are in one piece and provided for pressing directly on the junction pieces 109, while in the preferred embodiment shown Figure 2 using prestressing rings 114 which are screwed first in the thread 103 to obtain the desired prestressing at a fixed value.
  • the tapes 113 themselves are then screwed, which come to lock against the rings 114 without modifying the value of the prestressing and by performing a locking of the nut / lock nut type.
  • the slots 104 in the shell 101 allow this shell to vibrate under the influence of the piezoelectric motor, precisely according to the characteristic of a flextensor, giving the constricted central part of this shell the necessary flexibility.
  • the invention proposes, as shown in FIG. 4, to place in these slots during during the overmolding operation, a shuttering tool formed by a T-shaped section 404, the horizontal branch of which comes to rest on the inner face of the shell 101, and the vertical branch of which obstructs the slot by exceeding slightly from the outer surface of the hull.
  • This protrusion is for example provided to have a dimension substantially equal to half the thickness of the skin 105.
  • removes the obturation tools 404 which frees the slots 104 and leaves in front of these slots in the thickness of the skin a cavity 414 of width substantially equal to that of the slot. This cavity prevents the material constituting the skin from creeping inside the slot 104 under the effect of the pressure when the transducer is immersed.
  • Figure 4 The representation of Figure 4 is made in a radial section of the shell at one of the slots 104, and for the simplicity of the drawing the curvature of the shell and its sealing skin have not been shown.
  • the central part of the shell tends to shrink more and more and the slots close little by little.
  • the slots close completely and their edges come into contact. This particularly disturbs the operation of the transducer whose flexibility due to the slots disappears, and in practice it can no longer emit a sufficient acoustic level. This does not have a of great importance, since we have then exceeded the maximum depth for which the transducer is intended.
  • the mechanical strength of the shell increases significantly and in practice the diameter of the narrowed central part practically no longer decreases.
  • slots 104 it is also possible not to completely open the slots 104, so that they simply have the shape of a groove closed towards the inside of the shell by a material of low stiffness making it possible to seal .
  • Another variant consists in filling these slots, the width of which is for example 0.5 mm and the thickness (equal to the thickness of the shell) of 2.5 mm, with an extremely soft filling material, another polyurethane variety as that allowing to obtain the skin 105 for example, in order to obtain a filling both improving the tightness and fighting against the creep of the skin without interfering with the acoustic properties of the shell.
  • Transducers of this type are often used in the form of strings to make a linear antenna emitting radially.
  • the invention therefore proposes to machine the tapes 113 in the form of a ball joint pierced at its center to ensure the continuity of the central hole 112 which passes through the stack of rings 106
  • the successive transducers can be joined in a chain using, for example, a removable junction piece as shown in FIG. 5.
  • This junction piece comprises two identical parts 213 joined by a screw 214.
  • the assembly has two recesses spherical 215 in which can accommodate the ball joints of the ends 113 of two adjacent transducers. This allows a fixing having a certain flexibility to obtain a flexible complete linear antenna which can be wound on a drum of large diameter and slightly deform under the effect of the hydrodynamic forces applied when it is towed, so as not to risk breaking.
  • the invention also proposes to achieve the junction between two successive transducers using a module 301 externally having a shape quite similar to that of a transducer but whose ends are hollowed out to present spherical recesses 313 adapted to receive the spherical ends of the tapes 113.
  • the fixing between these tapes and these recesses will be done in any way known in the art of mechanics.
  • the parts 301 may be hollow to present a sufficient internal volume to be able to have electronic circuits there, such as amplifiers, multiplexers, and analog / digital converters intended to be connected to the piezoelectric ceramic rings 106 of the transducers in order to be able to feed them.
  • This connection will be made by cables passing through the axial hole 112 which extends from one end to the other of the transducer.
  • An axial hole of the same kind extending from one end to the other of the intermediate part 301 will make it possible to pass cables which extend along the antenna in order to be able to go up to the tractor building of this antenna.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
EP96401885A 1995-09-08 1996-09-03 Transducteur électroacoustique flextenseur Ceased EP0762381A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9510534 1995-09-08
FR9510534A FR2738704B1 (fr) 1995-09-08 1995-09-08 Transducteur electroacoustique flextenseur

Publications (1)

Publication Number Publication Date
EP0762381A1 true EP0762381A1 (fr) 1997-03-12

Family

ID=9482376

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96401885A Ceased EP0762381A1 (fr) 1995-09-08 1996-09-03 Transducteur électroacoustique flextenseur

Country Status (3)

Country Link
EP (1) EP0762381A1 (no)
FR (1) FR2738704B1 (no)
NO (1) NO963692L (no)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0903725A2 (en) * 1997-09-17 1999-03-24 The Minister Of National Defence Of Her Majesty's Canadian Government Folded shell projector
WO2000023822A2 (en) * 1998-10-16 2000-04-27 Western Atlas International, Inc. Slotted cylinder marine seismic method and source

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2822960B3 (fr) * 2001-03-30 2003-06-20 Thomson Marconi Sonar Sas Systeme de detection sous-marine basse frequence remorque

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3258738A (en) * 1963-11-20 1966-06-28 Honeywell Inc Underwater transducer apparatus
US4894811A (en) * 1987-05-18 1990-01-16 Raytheon Company Outboard-driven flextensional transducer
US4922470A (en) * 1988-11-15 1990-05-01 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of National Defence Of Her Majesty's Canadian Government Barrel stave projector
EP0568205A1 (en) * 1992-04-25 1993-11-03 Ferranti-Thomson Sonar Systems U.K. Limited Sonar transducer assembly

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3258738A (en) * 1963-11-20 1966-06-28 Honeywell Inc Underwater transducer apparatus
US4894811A (en) * 1987-05-18 1990-01-16 Raytheon Company Outboard-driven flextensional transducer
US4922470A (en) * 1988-11-15 1990-05-01 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of National Defence Of Her Majesty's Canadian Government Barrel stave projector
EP0568205A1 (en) * 1992-04-25 1993-11-03 Ferranti-Thomson Sonar Systems U.K. Limited Sonar transducer assembly

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0903725A2 (en) * 1997-09-17 1999-03-24 The Minister Of National Defence Of Her Majesty's Canadian Government Folded shell projector
EP0903725A3 (en) * 1997-09-17 2001-09-12 The Minister Of National Defence Of Her Majesty's Canadian Government Folded shell projector
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

Also Published As

Publication number Publication date
NO963692L (no) 1997-03-10
FR2738704A1 (fr) 1997-03-14
NO963692D0 (no) 1996-09-04
FR2738704B1 (fr) 1997-10-03

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