EP0434344B1 - Randgetrieben-Biegungswandler - Google Patents

Randgetrieben-Biegungswandler Download PDF

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Publication number
EP0434344B1
EP0434344B1 EP19900313788 EP90313788A EP0434344B1 EP 0434344 B1 EP0434344 B1 EP 0434344B1 EP 19900313788 EP19900313788 EP 19900313788 EP 90313788 A EP90313788 A EP 90313788A EP 0434344 B1 EP0434344 B1 EP 0434344B1
Authority
EP
European Patent Office
Prior art keywords
staves
driver
end plates
transducer
secured
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 - Lifetime
Application number
EP19900313788
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English (en)
French (fr)
Other versions
EP0434344A3 (en
EP0434344A2 (de
Inventor
George H. Cavanagh Iii
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.)
BAE Systems Aerospace Inc
Original Assignee
Hazeltine Corp
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Filing date
Publication date
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Publication of EP0434344A2 publication Critical patent/EP0434344A2/de
Publication of EP0434344A3 publication Critical patent/EP0434344A3/en
Application granted granted Critical
Publication of EP0434344B1 publication Critical patent/EP0434344B1/de
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • 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

  • This invention relates to a transducer apparatus which serve as sources, and detectors, of acoustic waves, wherein electrical (or magnetic) signals produce corresponding acoustic waves in a fluid medium, normally sea water.
  • transducers for underwater applications which employ continuous wave or modulated-wave input signals utilize piezoelectric, electrostrictive, or magnetostrictive energy-conversion materials.
  • Electrostrictive materials are available in a wide variety of shapes, including rectangular plates and annular discs which may be stacked to provide the amplitude and power of mechanical motion required by the transduction mechanism.
  • certain mechanical dimensional charges produced in the electrostrictive element (or stack of elements), as a result of application of an input signal are coupled to a driver element which interfaces with the water transmission medium.
  • the mechanical coupling arrangement is such that the maximum amplitude of motion in the driver element essentially equals the amplitude of the driving motion of the electrostrictive member.
  • the use of mechanical amplification is particularly advantageous in transducers designed for low-frequency applications.
  • the term "low-frequency" used herein generally applies to the region below approximately 1 khz. However, the features of this invention are not limited to that range. In the low-frequency region, significant transducer power output and driver motion are normally required. These requirements are best met through the use of large volumes of the electrostrictive energy-converting material, relatively large area of the flexural driver interface elements, and through the further use of transduction mechanisms which provide mechanical movement of the driver-interface elements which is amplified with respect to the mechanical movement of the electrostrictive energy-conversion element.
  • the ceramic-crystal type electrostrictive materials normally used in transducers have relatively low tensile strength, and, unless precautionary measures are taken, are subject to fracturing when strong electrical signals are applied. However, their compressive strengths are much greater. Therefore, in transducer applications, the stacks of crystals normally are subjected to a compressive "bias" to more nearly center the internal stress variations (produced by the electrical input signal) between the limits of the tensile and compressive strength of the crystal(s).
  • Fig. 1 shows a cross-section view of a prior art transducer which was claimed to essentially eliminate the undesired effect of the water pressure changes. This figure is taken from Figure 2 in United States Patent No. 3,258,738, "Underwater Transducer Apparatus", which was issued June 28, 1966. The present Fig. 1 has been somewhat simplified by omission of some detail not germane to the principles to be described here.
  • the embodiment shown is effective in providing efficiency which is improved over the earlier prior-art transducers employing elliptical tubes.
  • Figs. 2 and 3 are pictorial and cross-sectional views, respectively, of a prior-art cylindrical transducer employing the principles of the embodiment shown in Fig. 1.
  • Figs. 2 and 3 correspond (in somewhat simplified form) to the Figs. 5 and 6 in the aforereferenced United States Patent No. 3,258,738.
  • Objects of the present invention are to make it possible to provide a transducer in which the parts are more easily and less expensively fabricated, and in which manufacturing assembly is simplified; to provide a transducer utilizing a flexural cylindrical housing providing amplification of mechanical motion of the driver, and, if desired, resonance at some predetermined frequency; to provide a transducer having improved capability to withstand hydrostatic pressures; and to provide a transducer capable of effective low frequency applications.
  • US-A-3,258,738 describes an electro-acoustic transducer comprising: a hollow flexural cylindrical housing for producing acoustic signals in response to a stimulus; first and second end plates secured to the first and second opposite ends of the cylindrical housing; and means for producing said stimulus comprising a stack of energy conversion elements located in said housing, each element having an approximately centred aperture, and a tension member attached to said end plates and extending through the apertures of said elements to apply a compression force to said stacks.
  • the present invention as defined in Claim 1 is characterized in that: said hollow flexural cylindrical housing is formed by a plurality of individual parallel staves, each said stave having two opposite ends, being of predetermined shape, and being secured at its ends to said first and second end plates.
  • Fig. 1 is a cross-section view of a prior-art transducer employing a compliant tube in which the sides parallel to the cross-sectional major axis are concave.
  • Fig. 2 is a pictorial view of a prior-art cylindrical transducer.
  • Fig. 3 is a section view of the prior-art transducer shown in Fig. 2
  • Fig. 4 is an isometric drawing (partially sectional) of a transducer in accordance with the present invention.
  • Fig. 5 is a section side view of an improved transducer in accordance with the present invention.
  • Fig. 6 is a section end view of the transducer shown in Fig. 5.
  • Fig. 7 shows two views of one of the 12 staves which make up the sides of the transducer shown in Fig. 5.
  • FIG. 4 One embodiment of the present invention is illustrated by the isometric, partially cross-sectional drawing in Fig. 4.
  • Transducer 100 utilizes six flexural bars 101 fastened to two end plates 102 (the one at the distant end of the drawing not being visible).
  • the flexural bars are shaped as shown in Fig. 7 (to be described later) to form, in the assembled transducer 100, an outer surface which is concave with respect to the transducer's longitudinal axis.
  • Flexural bars 101 normally are fastened to end plates 102 by means of screws, not shown.
  • a stack of electrostrictive elements 103 (shown diagrammatically) is assembled within transducer 100 with its axis essentially coincident with the transducer's longitudinal axis.
  • a tension member 104 threaded at both ends, passes through holes in end plates 102 and through an axial hole through stack 103.
  • the tension member can be a rod, or bar with any shape, provided it meets the requirements detailed in the description below.
  • Boot material (such as rubber) is bonded to the outer surfaces of bars 101, at least to cover the outer region where the longitudinal edges of each bar meet the edges of adjoining bars. This detail is not shown, but it is noted here that hydrostatic pressure reinforces the bonding, whereas in the prior art cylindrical transducer of Figs. 2 and 3 the hydrostatic pressure may tend to tear the boot away from the inner cylindrical surface.
  • FIG. 5 A preferred embodiment of the invention is shown in cross-section in Fig. 5, and in the cut-away end view in Fig. 6, where the upper end plate is not shown.
  • this embodiment employs a greater number of flexural bars, twelve instead of six, and a large volume of electrostrictive, magnetostrictive, or other rare earth types of energy conversion material, to essentially fill the available space within the interior of the transducer shell.
  • the large volume of energy conversion material and larger radiating area provide generally desired lower Q (wider bandwidth) and greater power capability.
  • Fig. 5 twelve staves 201 are fastened to end plates 202 which have an end-view shape corresponding to a dodecagon, a twelve-sided regular polygon.
  • the staves are fastened to the end plates by means of screws which are not visible in Fig. 5, but for which provision is shown in Fig. 7.
  • the electrostrictive stack comprised of a stack of annular discs having a center hole 207, operates in the extensional mode, i.e. it expands and contracts along the longitudinal axis of the stack in response to corresponding variations in polarity of the input signal.
  • Tension member 204 which passes through holes 206 in end plates 202 and hole 207 in stack 203, is secured in place by threaded nuts 205 at each end.
  • boot or sealing material is assembled on the exterior surfaces of flexural bars 201, whereby hydrostatic pressure reinforces the bonding of the boot material to the bars.
  • transducer 200 An end view of transducer 200 is shown in in Fig. 6, in which the upper end plate is not shown.
  • the narrowing of the twelve flexural bars 201 as they curve inward to form the concave exterior surface is illustrated. These bars are fastened, as previously described, to lower end plate 202.
  • the twelve-sided upper end plate (not shown) fits within the polygon formed by the inner faces of the upper ends of flexural bars 201.
  • the end view of stack 203, with its center hole 207, is shown.
  • Tension member 204 (shown in Fig. 5) passes through hole 206 in lower end plate 202.
  • FIG. 7 To assist in visualization of transducer 200 shown in Figs 5 and 6, two views of one of the twelve staves are shown in Fig. 7.
  • the outer surface of stave 301 is shown in the left view.
  • Countersunk holes 303 (four at each end of the stave) provide for mounting the staves to the end plates of transducer 200 with flat-head screws. The heads of the screws, after assembly are flush with surfaces 304 at the ends of the staves in the side view at the right.
  • Surface 302 in that view corresponds to the outer surface of the transducer.
  • end plates 202 are caused to move outward, producing a positive pressure change in the fluid medium at their outer surfaces.
  • the two ends of flexural staves 201 are pulled in opposiste directions and their concave surfaces are caused to move outward, away from the longitudinal axis of tranducer 200, thereby producing a positive pressure change in the fuid medium at the outer surfaces of bars 201.
  • the pressure changes at the end plate surfaces and flexural stave surfaces are reinforcing.
  • the amplitude of motion of end plates 202 in opposing directions parallel to the transducer longitudinal axis cause an increased amplitude of motion in the center portion of the concave surfaces of bars 201.
  • the amplified motion of the concave surfaces of the staves coupled with the relatively large combined surface of the multiplicity of bars provides for significant power transfer to the fluid medium.
  • end plates 202 When the applied signal causes stack 203 to contract, end plates 202 are drawn inward toward each other in directions parallel to the longitudinal axis of transducer 200.
  • the end plate motion causes the concave surfaces of flexural staves 201 to flex inward toward the transducer's longitudinal axis.
  • reinforcing negative pressure changes occur in the fluid medium at the outer surfaces of the end plates and the flexural staves.
  • the invention is not limited to those numbers of staves.
  • the number of flexural staves employed, the degree of their concavity, their dimensions, and the mechanical properties of the materials of which the bars are composed may be varied to provide the desired Q, frequency range, and power capability of the transducer.
  • the apparatus may also serve as detectors of acoustic waves (or hydrophones), in which acoustic waves are detected and corresponding electrical (or magnetic) signals are produced.
  • detectors of acoustic waves or hydrophones
  • Such transducers find wide application in Sonar systems.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Claims (13)

  1. Elektroakustischer Wandler (100), der folgendes umfaßt:
    ein hohles biegbares zylindrisches Gehäuse zur Erzeugung akustischer Signale als Reaktion auf eine Anregung;
    erste und zweite Endplatten (102, 202), die an den ersten und zweiten entgegengesetzten Enden des zylindrischen Gehäuses befestigt sind; und
    Mittel zur Erzeugung der besagten Anregung mit einem in besagtem Gehäuse befindlichen Stapel (103, 203) energiewandelnder Elemente, wobei jedes Element eine ungefähr in der Mitte angeordnete Öffnung (207) aufweist, und einem Spannglied (104, 204), das an besagten Endplatten angebracht ist und sich durch die Öffnungen der besagten Elemente erstreckt, um eine Druckkraft auf besagte Stapel auszuüben, dadurch gekennzeichnet, daß besagtes hohles biegbares zylindrisches Gehäuse von einer Mehrzahl einzelner paralleler Stäbe (101, 201, 301) geformt wird, wobei jeder besagte Stab zwei entgegengesetzte Enden mit vorbestimmter Form aufweist und mit seinen Enden an besagten ersten und zweiten Endplatten (102, 202) befestigt ist.
  2. Wandler nach Anspruch 1, dadurch gekennzeichnet, daß besagte Stäbe (101, 201, 301) bezüglich des besagten Glieds (104, 204) konkav sind.
  3. Wandler nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß besagter Stapel (103, 203) eine Reihe ringförmiger energiewandelnder Scheiben umfaßt.
  4. Wandler nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß besagter Stapel (103, 203) eine Bewegung besagter Endplatten (102, 202) bedingt, wodurch besagte Stäbe eine Bewegungskomponente in einer zu der der besagten Endplatten senkrechten Richtung erfahren.
  5. Wandler nach einem der Ansprüche 1 bis 4, gekennzeichnet durch ein Mittel zur Abdichtung des Raumes zwischen den besagten Stäben, wobei hydrostatischer Druck auf besagtes Mittel die besagte Abdichtung verstärkt.
  6. Wandler nach Anspruch 5, dadurch gekennzeichnet, daß besagtes Abdichtmittel ein flexibles Material umfaßt, das auf die Außenseite des besagten Gehäuses aufgebracht wird.
  7. Wandler nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß das von den besagten Stäben (101, 201, 301) gebildete Gehäuse einen ungefähr kreisförmigen Querschnitt aufweist.
  8. Schallprojektor für Unterwasserbetrieb, gekennzeichnet durch folgendes: ein beabstandetes Paar polygonal geformter Endplatten (102, 202), einen keramischen Treiber (103, 203), der einen kleineren Querschnitt aufweist als jede Endplatte und zwischen den Endplatten angeordnet ist, und einen Satz Stäbe (101, 201, 301), die von einer Endplatte bis zur anderen befestigt sind, wobei jeder Stab konkav nach innen gewölbt ist in der Richtung des Treibers und durch einen Spalt von jedem anderen Stab getrennt ist.
  9. Projektor nach Anspruch 8, dadurch gekennzeichnet, daß jeder Stab (101, 201, 301) an den Endplatten (102, 202) durch eine Klebeverbindung und durch eine Schraube, die in jede Endplatte geschraubt ist, befestigt ist.
  10. Projektor nach Anspruch 8 oder 9, dadurch gekennzeichnet, daß der Treiber (103, 203) zylindrisch ist und eine ihn entlang seiner Längsachse durchlaufende Öffnung (207) aufweist und eine abdichtende Beschichtung innerhalb der Längsöffnung des Treibers umfaßt.
  11. Projektor nach einem der Ansprüche 8 bis 10, gekennzeichnet durch eine Endkappe, die an jeder Endplatte (102, 202) befestigt ist, um zu verhindern, das Innere des Treibers (103, 203) daß dem umgebenden Medium ausgesetzt ist, und wobei vom Treiber kommende elektrische Verdrahtung durch eine abdichtende Durchführungsdichtung in einer der Endkappen durchgeführt ist.
  12. Projektor nach einem der Ansprüche 8 bis 11, dadurch gekennzeichnet, daß besagter Satz Stäbe (101, 201, 301) ein Satz einzelner Stäbe ist, die mit jedem Ende an einer der Endplatten (102, 202) befestigt sind, und wobei jeder Stab von benachbarten Stäben durch einen Spalt getrennt ist, der sich über die Gesamtlänge jedes Stabes von einer Endplatte bis zur anderen Endplatte erstreckt.
  13. Projektor nach einem der Ansprüche 8 bis 12, dadurch gekennzeichnet, daß der Treiber (103, 203) zylindrisch ist, eine ihn entlang seiner Längsachse durchlaufende Öffnung (207) aufweist und einen Satz kreisförmiger Ringe umfaßt, wobei jeder Ring auf seinen flachen Oberflächen mit leitenden Elektroden beschichtet ist, die axial gepolt sind, um ihn piezoelektrisch aktiv zu machen, und an den nächsten Ring geklebt sind, wobei der Treiber (103, 203) zwischen die Endplatten (102, 202) geklebt ist; und wobei elektrische Verbinder an jedem Ring befestigt sind, und die elektrische Verdrahtung jedes Verbinders entlang der Länge des Treibers innerhalb der Längsöffnung (207) vergossen ist.
EP19900313788 1989-12-18 1990-12-17 Randgetrieben-Biegungswandler Expired - Lifetime EP0434344B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US45191389A 1989-12-18 1989-12-18
US451913 1989-12-18

Publications (3)

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EP0434344A2 EP0434344A2 (de) 1991-06-26
EP0434344A3 EP0434344A3 (en) 1991-11-13
EP0434344B1 true EP0434344B1 (de) 1995-08-23

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EP19900313788 Expired - Lifetime EP0434344B1 (de) 1989-12-18 1990-12-17 Randgetrieben-Biegungswandler

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EP (1) EP0434344B1 (de)
CA (1) CA2032044A1 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5805529A (en) * 1997-09-17 1998-09-08 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of National Defence Of Her Majesty's Canadian Government Folded shell projector (FSP)
US6535459B1 (en) 2002-04-18 2003-03-18 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of National Defence In Her Brittanic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Barrel stave projector-stave attachment

Family Cites Families (2)

* 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
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

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CA2032044A1 (en) 1991-06-19
EP0434344A3 (en) 1991-11-13
EP0434344A2 (de) 1991-06-26

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