Shaft resonance control

Patent metadata

Field	Value
Publication number	US-11300059-B2
Application number	US-201916598342-A
Country	US
Kind code	B2
Filing date	Oct 10, 2019
Priority date	Nov 9, 2018
Publication date	Apr 12, 2022
Grant date	Apr 12, 2022

Abstract

A method of actively controlling torsional resonance of a rotating shaft of an engine is provided. The shaft has a rotational velocity characterised by a low frequency, rotational velocity term and a high frequency, oscillatory term superimposed on the low frequency term, the oscillatory term being caused by torsional resonance. The method including: measuring the rotational velocity of the shaft; extracting the oscillatory term from the measured rotational velocity; and on the basis of the extracted oscillatory term, applying a torque component to the shaft, the torque component being modulated at the same frequency as the torsional resonance to counteract the torsional resonance.

First claim

The invention claimed is:

1. A method of actively controlling torsional resonance of a rotating shaft of an engine, the shaft having a rotational velocity characterised by (i) a low frequency, rotational velocity term and (ii) a high frequency, oscillatory term superimposed on the low frequency term, the oscillatory term being caused by torsional resonance, the method comprising:
measuring the rotational velocity of the shaft;
extracting the oscillatory term from the measured rotational velocity; and
applying a torque component to the shaft based on the extracted oscillatory term, the torque component being modulated at a same frequency as the torsional resonance to counteract the torsional resonance, the torque component being applied by modulating a flow rate of fuel to the engine, which includes an engine fuel control system that generates a fuel flow demand signal in response to an acceleration demand signal and a steady state fuel flow requirement, the flow rate of fuel to the engine being modulated by frequency modulating the fuel flow demand signal to generate the torque component at the same frequency as the torsional resonance.

2. The method according to claim 1 , wherein:
the measurement of the rotational velocity is performed at a frequency that is higher than the torsional resonance frequency of the shaft.

3. The method according to claim 1 , wherein the extraction of the oscillatory term from the measured rotational velocity includes demodulating the measured rotational velocity.

4. A system for reducing torsional resonance of a rotating shaft of an engine, the shaft having a rotational velocity characterised by (i) a low frequency, rotational velocity term and (ii) a high frequency, oscillatory term superimposed on the low frequency term, the oscillatory term being caused by torsional resonance, the system comprising:
a device configured to measure the rotational velocity of the shaft; and
a control unit configured to perform:
extracting the oscillatory term from the measured rotational velocity; and
generating and issuing a command to apply a torque component to the shaft based on the extracted oscillatory term, the torque component being modulated at a same frequency as the torsional resonance to counteract the torsional resonance, the torque component being applied by modulating a flow rate of fuel to the engine, which includes an engine fuel control system that generates a fuel flow demand signal in response to an acceleration demand signal and a steady state fuel flow requirement, the flow rate of fuel to the engine being modulated by frequency modulating the fuel flow demand signal to generate the torque component at the same frequency as the torsional resonance.

5. The system according to claim 4 , wherein the device for measuring the rotational velocity of the shaft includes:
a phonic wheel that is mounted coaxially to the shaft for rotation therewith, the phonic wheel having a circumferential row of detectable features; and
a sensor configured to detect a passage of the row of detectable features by generating an alternating measurement signal having a frequency that is a multiple of the rotational frequency of the shaft.

6. The system according to claim 4 , wherein:
the measurement of the rotational velocity by the device is performed at a frequency which is higher than the torsional resonance frequency of the shaft; and
the extraction of the oscillatory term from the measured rotational velocity by the control unit includes filtering the measured rotational velocity within a frequency range including the torsional resonance frequency.

7. A gas turbine engine having the system for reducing torsional resonance according to claim 4 .

Assignees

• Rolls Royce Plc

Inventors

• Bacic Marko

Classifications

• F02C9/48 Primary

  Control of fuel supply conjointly with another control of the plant (with nozzle section control F02K1/17) · CPC title

• F02C9/28 Primary

  Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed (F02C9/30 - F02C9/38, F02C9/44 take precedence) · CPC title

• G01P3/00

  Measuring linear or angular speed; Measuring differences of linear or angular speeds (G01P5/00 - G01P11/00 take precedence; {direction and speed indication G01P13/045}; counting mechanisms G06M) · CPC title

• F02C7/00

  Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants (controlling F02C9/00) · CPC title

• F05D2270/304

  Spool rotational speed · CPC title