US4047439A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic liquid supported linear accelerometer
Assignee: CHELTENHAM ATTITUDE SYSTEMS Ltd
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Filing: 1976-02-17
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Granted: 1977-09-13
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Expires: 1996-02-17
Abstract
Abstract A linear accelerometer comprises a proof mass in the form of a permanent bar magnet located in a tube containing a magnetic fluid such as a liquid with particles of magnetic material suspended therein. A servo circuit responsive to A.C. energized sensing coils is used to energize a D.C. electromagnet to maintain the proof mass in a central position in the tube.
Inventors
- 👤 Michael King Russell
- 👤 Anthony William Russell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:47
CPC Classifications
G; G01; G01P; G01P15/00; G01P15/02; G01P15/08; G01P15/13; G01P15/132
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
115 words
A linear accelerometer having a proof mass comprising a permanent bar magnet located in an elongate chamber of length in the direction of its longitudinal axis substantially greater than its width in directions perpendicular to said longitudinal axis and substantially filled with a magnetic fluid, the bar magnet being supported by the magnetic fluid with the magnetic axis of the bar magnet parallel to the longitudinal axis of the chamber, servo means responsive to movement of the bar magnet in the direction of the axis thereof for maintaining the bar magnet in a desired position and means for providing an electrical signal indicative of the force exerted on the bar magnet by the servo means.
Claim 2
Dependent Claim
115 words
A linear accelerometer having a proof mass comprising a permanent bar magnet located in an elongate chamber of length in the direction of its longitudinal axis substantially greater than its width in directions perpendicular to said longitudinal axis and substantially filled with a magnetic fluid, the bar magnet being supported by the magnetic fluid with the magnetic axis of the bar magnet parallel to the longitudinal axis of the chamber, servo means responsive to movement of the bar magnet in the direction of the axis thereof for maintaining the bar magnet in a desired position and means for providing an electrical signal indicative of the force exerted on the bar magnet by the servo means.
Claim 3
Dependent Claim
70 words
A linear accelerometer according to claim 1, wherein the servo means comprises a pair of sensing coils symmetrically disposed with respect to the desired position of the proof mass magnet and connected in a bridge circuit, and means responsive to the out-of-balance voltage from the bridge circuit for energising a D.C. electromagnet in order to apply a force to the proof mass magnet to urge it towards the desired position.
Claim 4
Dependent Claim
38 words
A linear accelerometer according to claim 2, in which the bridge circuit is an inductance bridge and the means responsive to the out-of-balance voltage therefrom comprises a demodulator arranged to produce a D.C. output to drive the electromagnet.
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) | 1980-09-12 | 1981-03-14 | 1981-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-12 | 1985-03-14 | 1985-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-12 | 1989-03-14 | 1989-09-13 | $7700.00 | Window Closed / Lapsed |