Patent EP0092424A2 successfully refreshed from Google Patents.
EP0092424A2
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EP
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Method and apparatus for damping aircraft rotor drive
Assignee: Colt Industries Inc
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Filing: 1983-04-19
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Granted: —
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Expires: 2003-04-19
Abstract
Abstract Damping of a helicopter rotor drive train, the drive train including the free turbines of a gas turbine engine 12, the aircraft main 34 and tail 36 rotors, and associated shafts and gears 30,32, 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 in opposite in phase to drive train resonances. The turbine speed signal NF is supplied to a damping circuit 44 which functions as a high pass filter and causes a phase shift to produce output signal NG * F . This is substracted from the fuel flow command signal NG * to cause the opposite phase torque to be developed.
Inventors
- 👤 Raymond D. Zagranski
- 👤 James J. Howlett
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 09:08
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/001; G; G05; G05D; G05D1/00; G05D1/08; G05D1/0808; G05D1/0858
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
115 words
A method of damping oscillation in a rotary wing aircraft rotor drive train, the drive train including a power turbine driven by the discharge of a gas generator, said method comprising the steps of: generating a signal commensurate with the speed of the power turbine; filtering the speed signal to eliminate variations thereof below a preselected frequency; adjusting the time constant of the filtered signal to provide a signal which is out of phase with the sensed speed variations; and modulating the flow of fuel to the gas generator as a function of the adjusted signal to cause the torque produced by the free turbine to oppose drive train speed variations above the preselected frequency.
Claim 2
Independent Claim
115 words
A method of damping oscillation in a rotary wing aircraft rotor drive train, the drive train including a power turbine driven by the discharge of a gas generator, said method comprising the steps of: generating a signal commensurate with the speed of the power turbine; filtering the speed signal to eliminate variations thereof below a preselected frequency; adjusting the time constant of the filtered signal to provide a signal which is out of phase with the sensed speed variations; and modulating the flow of fuel to the gas generator as a function of the adjusted signal to cause the torque produced by the free turbine to oppose drive train speed variations above the preselected frequency.
Claim 3
Dependent Claim
65 words
A method as claimed in claim 1 wherein the aircraft has a fuel control for controlling the supply of a combustible fuel at a variable flow rate to the gas generator, the fuel control including means for providing a gas generator speed command and wherein the adjusted signal which is out of phase with sensed speed variations is summed with the gas generator speed command.
Claim 4
Dependent Claim
43 words
A method as claimed in claim 2 wherein the fuel control provides gas generator fuel flow related temperature and acceleration limits and wherein the modulation of fuel flow to oppose decreases in speed are not permitted to exceed the acceleration and temperature limits.
Claim 5
Dependent Claim
47 words
A method as claimed in claim 3 wherein the gain of the filtered turbine speed signal is varied as a function of the frequency of any variations in sensed speed below the preselected frequency and is substantially constant and at its highest level above said preselected frequency.
Claim 6
Dependent Claim
154 words
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, comprising means for producing a gas generator fuel supply command signal, 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 7
Dependent Claim
154 words
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, comprising means for producing a gas generator fuel supply command signal, 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 8
Dependent Claim
78 words
Apparatus as claimed in claim 5 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 suppy command signal for altitude.
Claim 9
Dependent Claim
62 words
Apparatus as claimed in claim 6 wherein said modu- latinq 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.
Claim 10
Dependent Claim
62 words
Apparatus as claimed in claim 6 or 7 wherein said modulation means further comprises means for producing a further fuel supply command signal, said further fuel supply command signal being a function of an acceleration condition 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.
Claim 11
Dependent Claim
35 words
Apparatus as claimed in any of claims 5 to 8 including means for automatically varying the gain of the damping control signal as a function of gas generator discharge pressure and/or fuel flow command signal.
References Cited (Backward Citations)
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