US4531361A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Torsional mode suppressor
Assignee: Colt Industries Operating Corp
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Filing: 1984-02-13
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Granted: 1985-07-30
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Expires: 2004-02-13
Abstract
Abstract Damping of a helicopter rotor drive train, the drive train including the free turbines of a gas turbine engine propulsion system, the aircraft main and tail rotors, and associated shafts and gears, is accomplished through active modulation of the fuel flow to the engine gas generator. The fuel flow is varied such that a transient torque will be developed by the free turbines which is opposite in phase to drive train resonances.
Inventors
- 👤 Raymond D. Zagranski
- 👤 James J. Howlett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:30
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/001; F; F02; F02C; F02C9/00; G; G05; G05D; G05D1/00; G05D1/08; G05D1/0808; G05D1/0858; F05; F05D; F05D2260/00; F05D2260/96
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
162 words
In a fuel control system for a rotary wing aircraft, the aircraft having an engine comprising a gas generator and a power turbine mechanically decoupled from and driven by the gas generator, the fuel control system including means for producing a gas generator fuel supply command, the improvement comprising: means for providing a signal commensurate with power turbine speed; means responsive to said signal commensurate with turbine speed for providing a damping control signal commensurate with speed variations at frequencies in excess of a predetermined minimum, said damping control signal being out of phase with the sensed speed variations; means for modulating said fuel supply command signal with said damping control signal to produce variations in said fuel supply command signal; and means responsive to said fuel supply command signal for varying the rate of delivery of fuel to the gas generator to thereby cause the torque produced by the power turbine to oppose variations in speed above the said predetermined frequency.
Claim 2
Dependent Claim
162 words
In a fuel control system for a rotary wing aircraft, the aircraft having an engine comprising a gas generator and a power turbine mechanically decoupled from and driven by the gas generator, the fuel control system including means for producing a gas generator fuel supply command, the improvement comprising: means for providing a signal commensurate with power turbine speed; means responsive to said signal commensurate with turbine speed for providing a damping control signal commensurate with speed variations at frequencies in excess of a predetermined minimum, said damping control signal being out of phase with the sensed speed variations; means for modulating said fuel supply command signal with said damping control signal to produce variations in said fuel supply command signal; and means responsive to said fuel supply command signal for varying the rate of delivery of fuel to the gas generator to thereby cause the torque produced by the power turbine to oppose variations in speed above the said predetermined frequency.
Claim 3
Dependent Claim
77 words
The apparatus of claim 1 wherein said fuel control system provides a gas generator speed command signal and wherein said modulating means comprises: means for summing said speed command and damping control signals to produce a variable speed command signal; means responsive to said variable speed command signal and a signal commensurate with actual gas generator speed for producing a first fuel supply command signal; and means for compensating said first fuel supply command signal for altitude.
Claim 4
Dependent Claim
60 words
The apparatus of claim 2 wherein said modulating means further comprises: means for producing a second fuel supply command signal, said second fuel supply command signal being a function of a gas generator temperature limit; and means for selecting that one of said fuel supply command signals which commands the lesser fuel flow for delivery to said altitude compensation means.
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) | 1988-07-29 | 1989-01-28 | 1989-07-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-29 | 1993-01-28 | 1993-07-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-29 | 1997-01-28 | 1997-07-30 | $7700.00 | Window Closed / Lapsed |