EP0118329B1 - Geschwindigkeitshydrophon - Google Patents

Geschwindigkeitshydrophon Download PDF

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Publication number
EP0118329B1
EP0118329B1 EP84400132A EP84400132A EP0118329B1 EP 0118329 B1 EP0118329 B1 EP 0118329B1 EP 84400132 A EP84400132 A EP 84400132A EP 84400132 A EP84400132 A EP 84400132A EP 0118329 B1 EP0118329 B1 EP 0118329B1
Authority
EP
European Patent Office
Prior art keywords
fact
lamellae
hydrophone
hydrophone according
inertial mass
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.)
Expired
Application number
EP84400132A
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English (en)
French (fr)
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EP0118329A2 (de
EP0118329A3 (en
Inventor
Charles Maerfeld
Michel Josserand
Claude Gragnolati
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
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Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0118329A2 publication Critical patent/EP0118329A2/de
Publication of EP0118329A3 publication Critical patent/EP0118329A3/fr
Application granted granted Critical
Publication of EP0118329B1 publication Critical patent/EP0118329B1/de
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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
    • B06B1/0603—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 a piezoelectric bender, e.g. bimorph

Definitions

  • the invention relates to hydrophones and in particular to devices of this type which deliver an electrical signal in response to the vibrational speed of the incident acoustic waves, this response being flat over a wide frequency range.
  • acoustic pressure transducers arranged to provide an electrical signal characteristic of the pressure gradient within the acoustic wave.
  • Pressure gradient hydrophones therefore consist of a pair of pressure sensing cells at two separate locations.
  • the sensitivity varies as a function of the frequency.
  • the speed hydrophone to which the present invention applies comprises a mobile element immersed in the fluid, in order to match the particulate movement generated by the acoustic wave at a determined location.
  • This current advantageously constitutes the response signal independent of the frequency in a range situated above the natural resonant frequency of the deformable assembly comprising the reference mass.
  • the electroacoustic transducer element has a lamellar shape of sufficient flexibility to deliver an electrical signal substantially proportional to the particle speed of the fluid at the wavefront received by the hydrophone.
  • the particulate movement of the fluid is complex in particular by the fact that the transducer element vibrates in flexion, with a clearance linked to the distance which separates it from the inertial mass in which the transducer element is embedded. .
  • the transducer element comprises several suitably polarized layers.
  • the hydrophone according to the invention there is a choice between materials with low piezoelectric coefficients and with low modulus of elasticity such as piezoelectric polymers or materials with high piezoelectric coefficients and with high modulus of elasticity such than piezoelectric ceramics.
  • the choice of the thickness of materials used results in stiffness and sensitivity, but the extent and the particular shape of the deformable element are also important, because they condition the extent of the frequency range where a response flat can be expected.
  • the invention provides a speed hydrophone as defined in claim 1.
  • FIG. 1 a piezoelectric transducer element in the form of a disc 13 is seen.
  • This transducer element is produced for example in vinylidene lyfluoride (PVF 2 ).
  • Its main faces include electrodes 17 and 18 intended to collect the electric charges induced by piezoelectric effect when it operates as a sensor of acoustic vibrations propagated by the aqueous medium in which it is immersed.
  • FIG. 2 represents the zone 2 of the transducer element 13 of FIG. 1 delimited by the points A, B, C and D.
  • various mechanical tensions govern the equilibrium of the zone 2.
  • F 4 represents the radial tensions.
  • F 5 represents the normal to the main faces of the element 2 the tangential tensions.
  • F 3 represents the circumferential tensions. The invention proposes to eliminate these circumferential tensions which add stiffness to the disc 13, by making radial cuts which decompose the disc into flexible strips arranged in a crown.
  • FIG 3 is an elevational view of a hydrophone according to the invention.
  • This hydrophone comprises a piezoelectric transducer element 13 composed of identical flexible strips 31 arranged around a mass 10 acting as an embedding.
  • the cutouts 1 provide spaces between the strips 31 constituting the transducer element 13.
  • the mass 10 and composed of two blocks 101 and 102 between which the strips 31 are pinched.
  • the blocks 101 and 102 are made of high density material for example in tungsten.
  • the blocks 101 and 102 are axially pierced, in order to be tightened against the elements 31 by means of a bolt 11 and a nut 12.
  • each lamella 31 has a flared shape towards the periphery as illustrated in FIGS. 3 and 4.
  • Figure 5 is an elevational view of the hydrophone of Figures 3 and 4 associated with a current amplifier 30.
  • the strips 31 are provided with electrodes located on their main faces.
  • Contact pieces 14 connected to the electrical wires 15 and 16 are interposed between the blocks 101 or 102 and the main face of the strips 31.
  • the contact pieces 14 comprising on the side of the strips an electrically conductive element and on the side of the blocks 101 and 102 an insulating element. This arrangement ensures the paralleling of the electrodes located on the same side of the lamellae 31.
  • FIG. 6 represents the sectional view of a bimorph piezoelectric element composed of two layers 40 and 41 of piezoelectric material having opposite polarizations. These permanent electrical polarizations are parallel to the direction Oy. Thus a bending of this bimorph structure causes the appearance of opposite electric charges on the external faces of the layers 40 and 41.
  • the main external faces of the layers 40 and 41 are covered with metallic layers 42 and 43 forming electrodes. As shown in FIG. 5, one of the electrodes is connected by 15 to one terminal of the current amplifier 30, the other electrode being connected by 16 to the other terminal which is for example grounded.
  • the piezoelectric material of the layers 40 and 41 may in particular be a ceramic, for example PZT, a polymer, for example PVF 2 or a thin layer of Zn 0 deposited on a substrate.
  • the total thickness is for example 0.2 mm.
  • the electrodes 42 and 43 can be produced by vacuum evaporation deposition of a chromium layer 5 nm thick, an aluminum layer 50 nm thick and a layer of chromium 5 nm thick.
  • an insulating film for example a varnish.
  • Figure 7 shows the sectional view of a three-layer sensitive element.
  • This element comprises two piezoelectric layers 40 and 41 of polarization parallel to the direction Oy. Between the layers 40 and 41 is arranged a layer 44. If the layer 44 is chosen to be electrically conductive, the polarizations of the layers 40 and 41 can be same direction, and for example the layer 44 is grounded and the external electrodes are connected to the same output terminal. If on the other hand, the layer 44 is insulating, the polarizations of the layers 40 and 41 are necessarily opposite.
  • the layer 44 can for example be made of the same base material as the layers 40 and 41.
  • a particular embodiment of lamellae comprises two layers of piezoelectric PVF 2 40 and 41 and a layer 44 of PVF 2 loaded with carbon so as to be conductive of electricity. In other embodiments, the layer 44 is a non-polarized insulating layer.
  • Another variant of the invention comprises lamellae 31 composed of a single piezoelectric layer having an inhomogeneous piezoelectric polarization along the direction of the axis Oy.
  • FIG. 8 illustrates an ogival hydro-dynamic profile of the block 101 allowing it to undergo the least possible entrainment resulting from the particulate movement of the fluid in which the hydrophone is immersed.
  • FIG. 9 shows a variant of the embodiment of FIG. 3.
  • the speed hydrophone comprises a stepped assembly of sensors 32 whose lamellae are arranged in crowns.
  • the strips 31 have a flared shape towards the periphery.
  • the strips 31 have their electrodes placed in parallel by means of contact piece 70. These have two conductive faces 71 separated by an insulating layer 72. A contact piece 70 is arranged between two sensors in a ring 32 increases the sensitivity to incident acoustic waves.
  • the invention provides for providing the peripheral end of the strips 31 with weights, for example of light alloy.
  • weights for example of light alloy.
  • all of these weights can form a strapping ring mounted so as to prevent it from acting as a stiffener.
  • FIG. 10 represents an embodiment comprising an inertial mass forming a cylindrical conduit 80.
  • the piezoelectric electro-acoustic transducer comprises a single ring 32 of strips 31. The strips are separated from each other by radial slots 1.
  • the ring 32 is embedded in the cylindrical conduit 80 by a pinch groove 86.
  • the leading edges 89 of the cylindrical conduit 80 are hydrodynamically profiled.
  • the cylindrical conduit 80 is closed by waterproof membranes 65.
  • the interior of the cylindrical duct 80 is a closed space which can be filled with an electrical insulating liquid allowing good adaptation of acoustic impedances.
  • the membranes 65 transmit the vibratory movement of the water to the insulating liquid.
  • FIG. 11 is a meridian section of a hydrophone comprising an inertial mass forming a cylindrical conduit 80. Crowns 32 of lamellae 31 are embedded by their periphery inside the cylindrical conduit 80. The electrodes carried by the faces of the lamellae 31 are connected in parallel to the inputs of a current amplifier via contact sockets 81. These comprise two conductive layers 84 separated by a ring of insulating material 85. A contact socket 81 is provided between two rings 32 successive strips 31.
  • the cylindrical conduit 80 is closed by waterproof membranes 65.
  • the interior of the cylindrical conduit 80 is a closed space which can be filled with an electrical insulating liquid to ensure the transmission of the acoustic waves.
  • the cylindrical conduit 80 can be filled with oil with high insulating power.
  • FIGS. 12 and 13 give two exemplary embodiments of lamella crowns 31.
  • FIG. 12 illustrates an exemplary embodiment advantageously using ceramic as the piezoelectric material.
  • the separate strips 31 are arranged radially and attached to the center by a connection piece of light material 82. They are separated from each other by triangular spaces 1.
  • FIG. 13 illustrates an exemplary embodiment advantageously using PVF 2 as piezoelectric material .
  • the crown 32 illustrated in FIG. 13 can be used in particular with the hydrophones illustrated in FIGS. 3, 4, 5, 9, 10 and 11.
  • the crown 32 is obtained by making cuts 1 in a disc, for example made of PVF 2 .
  • the cutouts 1 separate the crown 32 into strips 31.
  • To embed the crown 32 a hole 86 is made allowing it to be mounted in the devices illustrated in FIGS. 3, 4, 5 and 9.
  • the rings 32 or the lamellae can be cut from a disc of piezoelectric polymer, for example PVF 2 , obtained by forging. Obtaining such a disc is described in patent application EP-A-87 991, filed by the Applicant and published on September 7, 83, after the priority date of the present application. In such discs, the mechanical and piezoelectric anisotropy is invariant in concentric circles.
  • the diagram in Figure 14 shows the shape of a speed hydrophone frequency response curve.
  • the diagram gives the frequency f on the abscissa on the ordinate the amplitude of the electrical signal S (f) supplied by the hydrophone in response to an incident acoustic wave of predetermined level and of frequency f.
  • the curve comprises a plateau 50 which starts from the resonance frequency f R and which extends towards the high frequencies, apart from the conventional accidents.
  • the range 50 of constant sensitivity is limited towards the low frequencies by a range 54 of resonance.
  • the sensitivity may have a point 53 or a round 61 depending on the expected damping.
  • the response drops at a slope of 12 dB / octave.
  • the frequency response characteristic of FIG. 14 was obtained by connecting the hydrophone to an amplifier having a low electrical impedance at any frequency relative to the internal impedance of the hydrophone. At high frequencies, this load condition of the speed hydrophone is no longer satisfied since the capacitive reactance decreases with frequency, but other phenomena occur to limit upwards the operating range at constant level.
  • FIGS 15, 16 and 17 are explanatory figures for understanding the frequency behavior of the speed hydrophone according to the invention.
  • the model used comprises a mechanical excitation by the acoustic wave symbolized by a generator 55 of particulate speed.
  • the flexibly deformable piezoelectric strips are symbolized by a spring 56 which connects the generator 55 to the inertial mass 57.
  • the oscillogram 51 represents as a function of time the particle displacement communicated to the spring 56 and to the suspended mass 57. It is assumed that the incident acoustic wave has no direct motive action on the suspended mass 57.
  • the passive spring-mass assembly then forms a resonant cell having a natural frequency f R as a function of the ratio where k represents the stiffness of the spring and m the mass used for embedding the slats 31.
  • Figure 15 shows the oscillogram 52 which characterizes the phase concordance movement of the mass 57 and of the link between the generator 55 and the spring 56. It has been assumed in FIG. 15 that the excitation frequency is clearly below f R. The deformation 58 of the spring 56 is small since its value is linked to the difference of the dice placement illustrated by oscillograms 51 and 52.
  • FIG. 16 corresponds to the case where the excitation frequency corresponds to the resonance frequency f R.
  • the displacements of the mass 57 are in phase opposition with those of the connection point between the generator 55 and the spring 56.
  • the deformation 58 of the spring 56 may have a magnitude greater than the amplitude of the excitation.
  • FIG. 17 corresponds to the case where the excitation frequency f is significantly higher than the resonance frequency f R.
  • the inertial mass 57 remains almost immobile so that the displacements communicated by the generator 55 apply almost completely to the deformation 58 of the spring 56.
  • This operating mode corresponds to the sensitivity plate 50 of FIG. 14.
  • Figure 18 is a simplified electrical diagram of the connection between the speed hydrophone and its amplifier.
  • the capacitor 59 of capacity C represents the internal admittance of the hydrophone.
  • the Y value admittance 60 represents the amplifier input circuit. According to this diagram, the operation as a speed hydrophone is ensured if the current i generated by piezoelectric effect passes as much as possible through the amplifier circuit, which supposes that the admittance j ⁇ C is less than Y.
  • the magnitude input of the amplifier is roughly the short circuit current of the piezoelectric generator.

Claims (14)

1. Hydrophone, dessen bewegliche Einheit wenigstens ein piezoelektrisches Wandlerelement in Lamellenform (13) umfasst, das durch Einlassen in eine Trägheitsmasse (10) mit dieser verbunden ist, dadurch gekennzeichnet, dass das genannte Wandlerelement (13) die Partikelgeschwindigkeit des fluiden Mediums abfühlt, in welches es eingetaucht ist, dass die Trägheitsmasse (10) eine gestreckte, im wesentlichen bezüglich einer Längsache rotationssymmetrische Form aufweist und dass dieses Element aus flexiblen Lamellen zusammengesetzt ist, die in einer Ebene senkrecht zur Längsachse angeordnet, radial getrennt (31) und kranzförmig angebracht sind, wobei jede dieser Lamellen (31) ein in die genannte Trägheitsmasse (10) eingelassenes Ende aufweist.
2. Hydrophon nach Anspruch 1, dadurch gekennzeichnet, dass die von den Lamellen (31) getragenen Elektroden parallel an einen Stromverstärker (30) angeschlossen sind.
3. Hydrophon nach Anspruch 1, dadurch gekennzeichnet, dass die von den Lamellen (31) getragenen Elektroden in Reihenschaltung mit einem Stromverstärker (30) verbunden sind.
4. Hydrophon nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass das piezoelektrische Wandlerelement (13) von bimorphem oder dreilagigem Typ ist.
5. Hydrophon nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass das piezoelektrische Wandlerelement (13) aus einem piezoelektrischen Polymer hergestellt ist.
6. Hydrophon nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass das piezoelektrische Wandlerelement (13) aus piezoelektrischer Keramik hergestellt ist.
7. Hydrophon nach Anspruch 5, dadurch gekennzeichnet, dass es Lamellen (31) aufweist, die aus Scheiben aus PVF2 hergestellt sind, welche durch Schmieden gewonnen wurden, wobei die radialen Ausschnitte (1) dazu bestimmt sind, den Biegewiderstand des Wandlerelements (13) zu vermindern.
8. Hydrophon nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass die Lamellen (31) eine zum Umfang des genannten Kranzes hin erweiterte Form aufweisen.
9. Hydrophon nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass die Lamellen (31) des piezoelektrischen Wandlerelements (13) radial in eine zentrale Trägheitsmasse (10) eingelassen sind, welche mit je einer Flachseite (19) gegenüber jeder Lamelle (31) versehen ist.
10. Hydrophon nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass die Lamellen (31) des piezoelektrischen Wandlerelements (13) im Inneren einer zylindrischen Leitung (80) angeordnet ist, welche die Trägheitsmasse (10) dieses Hydrophons bildet.
11. Hydrophon nach Anspruch 10, dadurch gekennzeichnet, dass die zylindrische Leitung (80), welche dieTrägheitsmasse bildet, durch undurchlässige Membranen verschlossen ist, um ihre Füllung mit einem elektrisch isolierenden fluiden Medium, welches Schallwellen überträgt, zu gestatten.
12. Geschwindigkeitsaufnehmer-Hydrophon nach Anspruch 10 oder 11, dadurch gekennzeichnet, dass die zylindrische Leitung (80), welche die Trägheitsmasse bildet, mit Flachseiten versehen ist, die gegenüber jeweils einer Lamelle (31) ausgerichtet sind.
13. Geschwindigkeitsaufnehmer-Hydrophon nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die Lamellen (31) rechtwinklige Form haben.
14. Geschwindigkeitsaufnehmer-Hydrophon nach einem der Ansprüche 1 bis 12, dadurch gekennzeichnet, dass die Lamellen (31) die Form von Kreissektoren aufweisen.
EP84400132A 1983-01-28 1984-01-20 Geschwindigkeitshydrophon Expired EP0118329B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8301336A FR2540325A1 (fr) 1983-01-28 1983-01-28 Hydrophone de vitesse
FR8301336 1983-01-28

Publications (3)

Publication Number Publication Date
EP0118329A2 EP0118329A2 (de) 1984-09-12
EP0118329A3 EP0118329A3 (en) 1984-10-24
EP0118329B1 true EP0118329B1 (de) 1987-06-03

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EP84400132A Expired EP0118329B1 (de) 1983-01-28 1984-01-20 Geschwindigkeitshydrophon

Country Status (7)

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US (1) US4547870A (de)
EP (1) EP0118329B1 (de)
JP (1) JPS59143496A (de)
AU (1) AU2380084A (de)
CA (1) CA1231169A (de)
DE (1) DE3464107D1 (de)
FR (1) FR2540325A1 (de)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2656971B1 (fr) * 1990-01-05 1992-09-04 Thomson Csf Hydrophone basse frequence et antenne sonar comportant de tels hydrophones.
GB2258364A (en) * 1991-07-30 1993-02-03 Intravascular Res Ltd Ultrasonic tranducer
US5457359A (en) * 1993-08-06 1995-10-10 Olin Corporation Control for electroluminescent loads
FR2766953B1 (fr) * 1997-07-29 1999-10-01 Renault Dispositif de controle acoustique dans un volume
NO312792B1 (no) * 2000-06-23 2002-07-01 Meditron As Mekanoelektrisk sensor
PL359370A1 (en) 2000-06-23 2004-08-23 Meditron As Two-way mechano-electrical transducer
US6693849B1 (en) * 2002-10-03 2004-02-17 Adolf Eberl Piezoelectric audio transducer
NL2000501C2 (nl) * 2007-02-22 2008-08-25 Consulo Inrichting en werkwijze voor het diagnosticeren van een aandoening.
CN112153528B (zh) * 2020-10-30 2022-08-23 中国航空工业集团公司洛阳电光设备研究所 复合钹式压电陶瓷换能器的矢量水听器

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US2842685A (en) * 1955-12-23 1958-07-08 Gulton Ind Inc Bender tuned array
US3104334A (en) * 1959-09-15 1963-09-17 Endevco Corp Annular accelerometer
US3079584A (en) * 1959-10-23 1963-02-26 Claude C Sims High pressure piezoelectric hydrophone with tungsten backing plate
US3325780A (en) * 1965-10-21 1967-06-13 John J Horan Flexural transducers
US3603921A (en) * 1968-12-18 1971-09-07 Magnavox Co Sound transducer
US3706967A (en) * 1971-01-21 1972-12-19 Us Navy Underwater acoustic projector
JPS5318893B2 (de) * 1971-12-03 1978-06-17
US3992693A (en) * 1972-12-04 1976-11-16 The Bendix Corporation Underwater transducer and projector therefor
JPS5214156B2 (de) * 1972-12-27 1977-04-19
DE2346649A1 (de) * 1973-09-17 1975-03-27 Ngk Spark Plug Co Ultraschallgeber
FR2263656B1 (de) * 1974-03-05 1978-01-06 France Etat
US4268912A (en) * 1978-06-06 1981-05-19 Magnavox Government And Industrial Electronics Co. Directional hydrophone suitable for flush mounting

Also Published As

Publication number Publication date
EP0118329A2 (de) 1984-09-12
CA1231169A (en) 1988-01-05
DE3464107D1 (en) 1987-07-09
JPS59143496A (ja) 1984-08-17
FR2540325A1 (fr) 1984-08-03
AU2380084A (en) 1984-08-02
EP0118329A3 (en) 1984-10-24
US4547870A (en) 1985-10-15

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