Patent JPS60194031A successfully refreshed from Google Patents.
US4361879A
Expired / Lapsed
US
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Ferrofluid transducer
Assignee: United States Department of the Navy
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Filing: 1980-08-25
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Granted: 1982-11-30
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Expires: 2000-08-25
Abstract
Abstract An underwater sound generator composed of a ferrofluid contained within a toroidal container which has a rigid bottom and top and elastic cylindrical side walls. A coil of wire links the toroidal container and is adapted to be connected to a dc bias source to produce a biasing magnetic field, H BIAS , which drives the magnetization of the ferrofluid well into saturation. Two oppositely wound coils of wire respectively link the inner side wall and the outer side wall and are adapted to be connected in series to an ac signal source to produce a time-varying magnetic field, H AC , which modulates H BIAS . The wires are equally spaced in the volume occupied by the ferrofluid. The gradient of H AC in the radial direction provides the time-varying force on the ferrofluid. The resulting ferrofluid motion in the radial direction is transmitted through the outer elastic side wall to supply acoustic motion to the surrounding water.
Inventors
- 👤 Pieter S. Dubbelday
- 👤 Robert W. Timme
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:40
CPC Classifications
H; H04; H04R; H04R15/00; G; G10; G10K; G10K9/00; G10K9/12
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
106 words
An underwater, low-frequency sound generator comprising: a toroidal container having a rigid bottom and a rigid top, and elastic inner and outer cylindrical side walls; a ferrofluid filling the toroidal container; and magnetic-field-reducing means having elements inside the toroidal container and inside the ferrofluid itself for producing in the circumferential direction of the toroidal container both a biasing magnetic field and a time-varying magnetic field, the time-varying magnetic field providing a force causing the ferrofluid to move in the radial direction of the toroidal container, the motion of the ferrofluid being transmitted through the elastic outer side walls to supply acoustic motion to a surrounding medium.
Claim 2
Dependent Claim
106 words
An underwater, low-frequency sound generator comprising: a toroidal container having a rigid bottom and a rigid top, and elastic inner and outer cylindrical side walls; a ferrofluid filling the toroidal container; and magnetic-field-reducing means having elements inside the toroidal container and inside the ferrofluid itself for producing in the circumferential direction of the toroidal container both a biasing magnetic field and a time-varying magnetic field, the time-varying magnetic field providing a force causing the ferrofluid to move in the radial direction of the toroidal container, the motion of the ferrofluid being transmitted through the elastic outer side walls to supply acoustic motion to a surrounding medium.
Claim 3
Dependent Claim
19 words
The generator recited in claim 1 wherein the magnetic-field-producing means includes: a coil of wire linking the toroidal container.
Claim 4
Dependent Claim
57 words
The generator recited in claim 1 wherein the magnetic-field-producing means includes: a first coil of wire linking one side wall of the toroidal container; and a second coil of wire linking the other side wall of the toroidal container and connected in series with the first coil. the first and second coils being wound in opposite sense.
Claim 5
Dependent Claim
25 words
The generator recited in claim 2 wherein the magnetic-field-producing means includes: a dc bias source connected to the coil of wire linking the toroidal container.
Claim 6
Dependent Claim
25 words
The generator recited in claim 3 wherein the magnetic-field-producing means includes: an ac signal source connected to the series-connected first and second coils of wire.
Claim 7
Dependent Claim
24 words
The generator recited in claim 1 wherein the ferrofluid includes: a hydrocarbon carrier liquid, and subdomain ferromagnetic particles colloidally suspended in the carrier liquid.
Claim 8
Dependent Claim
46 words
The generator recited in claim 3 wherein: segments of the first coil of wire and the second coil of wire inside the toroidal container run parallel to the central axis of the toroidal container, and are equally spaced in the radial direction of the toroidal container.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-11-29 | 1986-05-31 | 1986-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-29 | 1990-05-31 | 1990-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-29 | 1994-05-31 | 1994-11-30 | $7700.00 | Window Closed / Lapsed |