US5099461A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Underwater electroacoustic transducers
Assignee: KILDARE Corp
•
Filing: 1989-02-14
•
Granted: 1992-03-24
•
Expires: 2009-02-14
Abstract
Abstract The FLEXBAR is a sonar transducer element that is basically a piezoceramic "free-free" flexure bar, but modified so as to radiate as a "monopole" rather than as a "dipole", and retaining the unique properties of being nodally mounted and dynamically balanced. One of the important consequences of this simple modification is the fact that the reaction forces on the FLEXBAR mountings and, the concomitant structure-borne vibrations, are virtually eliminated. This property, and related properties, result in unexpected but significant improvement in the performance of low-frequency, high-power, board-band sonar transducer arrays.
Inventors
- 👤 James W. Fitzgerald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:15
CPC Classifications
B; B06; B06B; B06B1/00; B06B1/02; B06B1/06; B06B1/0603
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
256 words
An improved underwater acoustic transducer comprised of: a free-free flexure bar; means for electromechanically driving the said bar in flexural vibration over a band of frequencies having as its central frequency a frequency, substantially corresponding to the lowest free-free flexural mode of the said bar; means for mounting said flexure bar substantially at the two nodal lines characteriatic of the said lowest free-free flexural vibrational mode of the said bar, said mountings having elastomeric members partially isolating said mountings from the vibration of the said flexure bar; means for affixing said flexure bar and its said nodal mountings into a gas-filled water-tight housing in such a manner that the flexure bar can vibrate freely on its nodal mountings without substantial mechanical coupling to said mountings or said housing; means for mechano-acoustically coupling to the water only the central portion of the outer surface of said mounted bar lying between the said two nodal lines, so that when electromechanically driven in flexural vibration, the said flexure bar will radiate acoustic energy into the water from said central portion; means for allowing those outer portions of said flexure bar lying outside of the said two nodal lines to vibrate freely in the gas-filled interior of said housing without mechano-acoustic coupling to the water, thus preventing acoustic radiation from said outer portions which would be out of phase with said acoustic radiation from said central portion; and thus allowing the said underwater acoustic transducer to radiate acoustic energy into the water essentially as a monopole, rather than a dipole.
Claim 2
Dependent Claim
256 words
An improved underwater acoustic transducer comprised of: a free-free flexure bar; means for electromechanically driving the said bar in flexural vibration over a band of frequencies having as its central frequency a frequency, substantially corresponding to the lowest free-free flexural mode of the said bar; means for mounting said flexure bar substantially at the two nodal lines characteriatic of the said lowest free-free flexural vibrational mode of the said bar, said mountings having elastomeric members partially isolating said mountings from the vibration of the said flexure bar; means for affixing said flexure bar and its said nodal mountings into a gas-filled water-tight housing in such a manner that the flexure bar can vibrate freely on its nodal mountings without substantial mechanical coupling to said mountings or said housing; means for mechano-acoustically coupling to the water only the central portion of the outer surface of said mounted bar lying between the said two nodal lines, so that when electromechanically driven in flexural vibration, the said flexure bar will radiate acoustic energy into the water from said central portion; means for allowing those outer portions of said flexure bar lying outside of the said two nodal lines to vibrate freely in the gas-filled interior of said housing without mechano-acoustic coupling to the water, thus preventing acoustic radiation from said outer portions which would be out of phase with said acoustic radiation from said central portion; and thus allowing the said underwater acoustic transducer to radiate acoustic energy into the water essentially as a monopole, rather than a dipole.
Claim 3
Dependent Claim
21 words
An improved underwater acoustic transducer as set forth in claim 1, but comprised of a plurality of said free-free flexure bars.
Claim 4
Dependent Claim
120 words
An improved underwater acoustic transducer as set forth in claim 1 or claim 2 wherein the free-free flexure bar is comprised of two modified end sections lying outside of the nodal lines of the said free-free flexure bars which are rigidly attached to the central portion of the said free-free bar and extend at substantially right angles to, and on the opposite side of, the central radiating surface of the said free-free flexure bar, where said end sections would provide substantially the same total inertia, both translational and rotational, taken about the nodal lines, as would be provided by uniform end sections extending outside of the nodal lines and parallel to the central radiating face of the free-free flexure bar.
Claim 5
Dependent Claim
51 words
An improved underwater acoustic transducer as set forth in claim 3 wherein the said free-free flexure bar is comprised of said modified end sections which have a portion of their surfaces that are contiguous with the central radiating surface recessed so as to avoid vibrational interference with a transducer cover plate.
Claim 6
Dependent Claim
32 words
An improved underwater acoustic transducer comprised of said free-free flexure bars as set forth in claim 3 wherein the means for electromechanically driving said bars in flexural vibrations is a piezoelectric means.
Claim 7
Dependent Claim
32 words
An improved underwater acoustic transducer comprised of said free-free flexure bars as set forth in claim 3 wherein the means for electromechanically driving said bar in flexural vibration is a magnetostrictive means.
Claim 8
Dependent Claim
34 words
An improved underwater acoustic transducer comprised of said free-free flexure bars as set forth in claim 3 wherein the means for electromechanically driving said bar in flexural vibration is a magnetic electrodynamic (moving-coil) means.
Claim 9
Dependent Claim
35 words
An improved underwater acoustic transducer comprised of said free-free flexure bars as set forth in claim 3 wherein the means for electromechanically driving said bar in flexural vibration is a variable magnetic reluctance (moving-armature) means.
Claim 10
Dependent Claim
29 words
An improved underwater acoustic transducer comprised of said free-free flexure bars as set forth in claim 5 wherein the piezoelectric means is one of the class of polarized piezoceramics.
Claim 11
Dependent Claim
41 words
An improved underwater acoustic transducer comprised of said free-free flexure bars as set forth in claim 9 wherein means are provided to subject the polarized piezoceramic to a substantially permanent precompression mechanical bias in the course of fabrication of said bars.
Claim 12
Dependent Claim
182 words
An improved vibratile element, suitable for use in a transducer, comprised of: a free-free flexure bar; means for electromechanically driving said bar in flexural vibration over a band of frequencies having as its central frequency a frequency substantially corresponding to the lowest free-free flexural vibrational mode of the said bar; means for mounting said flexure bar substantially at the two nodal lines characteristic of the said lowest free-free flexural vibrational mode of the said bar, said mountings having elastomeric members partially isolating said mountings from the vibrations of said flexure bar; two modified end sections lying outside of the nodal lines of the said free-free flexure bars which are rigidly attached to the central portion of said free-free bar and extend at substantially right angles to, and on the same side of, central portion of said bar, where said end sections would provide substantially the same total inertia, both translational and rotational, taken about the nodal lines, as would be provided by uniform end sections extending outside of the nodal liens and parallel to the central portion of said free-free flexure bar.
Claim 13
Dependent Claim
182 words
An improved vibratile element, suitable for use in a transducer, comprised of: a free-free flexure bar; means for electromechanically driving said bar in flexural vibration over a band of frequencies having as its central frequency a frequency substantially corresponding to the lowest free-free flexural vibrational mode of the said bar; means for mounting said flexure bar substantially at the two nodal lines characteristic of the said lowest free-free flexural vibrational mode of the said bar, said mountings having elastomeric members partially isolating said mountings from the vibrations of said flexure bar; two modified end sections lying outside of the nodal lines of the said free-free flexure bars which are rigidly attached to the central portion of said free-free bar and extend at substantially right angles to, and on the same side of, central portion of said bar, where said end sections would provide substantially the same total inertia, both translational and rotational, taken about the nodal lines, as would be provided by uniform end sections extending outside of the nodal liens and parallel to the central portion of said free-free flexure bar.
Claim 14
Dependent Claim
47 words
An improved vibratile element, suitable for use in a transducer, as set forth in claim 11, wherein means are provided to change the mass of said modified end sections so as to change the frequency substantially corresponding to the lowest free-free flexural vibrational mode of said bar.
Claim 15
Dependent Claim
54 words
An improved vibratile element, suitable for use in a transducer, as set forth in claim 11, wherein means are provided to change the moment of inertia, taken about the nodal lines, of said modified end sections so as to change the frequency substantially corresponding to the lowest free-free flexural vibrational mode of said bar.
Claim 16
Dependent Claim
38 words
An improved vibratile element, suitable for use in a transducer, as set forth in claim 11, or claim 12, or claim 13, wherein the means for electromechanically driving said vibratile element in flexural vibration is a piezoelectric means.
Claim 17
Dependent Claim
38 words
An improved vibratile element, suitable for use in a transducer, as set forth in claim 11, or claim 12, or claim 13, wherein the means for electromechanically driving said vibratile element in flexural vibration is a magnetostrictive means.
Claim 18
Dependent Claim
40 words
An improved vibratile element, suitable for use in a transducer, as set forth in claim 11, or claim 12, or claim 13, wherein the means for electromechanically driving said vibratile element in flexural vibration is a magnetic electrodynamic (moving-coil) means.
Claim 19
Dependent Claim
41 words
An improved vibratile element, suitable for use in a transducer, as set forth in claim 11, or claim 12, or claim 13, wherein the means for electromechanically driving said vibratile element in flexural vibration is a variable magnetic reluctance (moving-armature) means.
Claim 20
Dependent Claim
22 words
An improved vibratile element as set forth in claim 14 wherein the piezoelectric means is one of a class of polarized piezoceramics.
Claim 21
Dependent Claim
36 words
An improved vibratile element as set forth in claim 15 wherein means are provided to subject the polarized piezoceramic to a substantially permanent precompression mechanical bias in the course of fabrication of the said vibratile element.
Claim 22
Dependent Claim
25 words
An improved vibratile element as set forth in claim 19, wherein a pair of tapered wedges are the means for obtaining the said mechanical bias.
Claim 23
Dependent Claim
28 words
An improved vibratile element as set forth in claim 19, wherein a pair of tapered pins and matching blocks are the means for obtaining the said mechanical bias.
Claim 24
Dependent Claim
29 words
An improved vibratile element as set forth in claim 19, wherein a pair of tapered threaded bolts and matching block are the means for obtaining the said mechanical bias.
References Cited (Backward Citations)
US3704385A
Cited
US3982142A
Cited
US4010441A
Cited
US4131874A
Cited
US4429247A
Cited
US4593160A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-24 | 1995-09-23 | 1996-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-24 | 1999-09-23 | 2000-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-24 | 2003-09-23 | 2004-03-24 | $7700.00 | Window Closed / Lapsed |