Mechanical flywheel for bowed rotor mitigation

Patent metadata

Field	Value
Publication number	US-10378442-B2
Application number	US-201715475791-A
Country	US
Kind code	B2
Filing date	Mar 31, 2017
Priority date	Mar 31, 2017
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

A mechanical flywheel used to power an aircraft system. In one example, the flywheel is used to rotate a rotor shaft in the aircraft's engine and prevent bowing of the rotor shaft caused by a thermal gradient. In another example, the mechanical flywheel provides electrical power at peak demand times. In yet another example, the flywheel is used as a load source or sink by the engine's control system so as to aid engine operability and engine acceleration rates during abnormal flight conditions.

First claim

What is claimed is:

1. An apparatus, comprising:
an aircraft engine including a rotor shaft, wherein the rotor shaft is inside a casing; and
a flywheel; and
a transmission connecting the rotor shaft and the flywheel, and wherein:
second rotational energy in the flywheel is generated from first rotational energy of the rotor shaft transmitted to the flywheel through the transmission,
after shutdown of the aircraft engine, the transmission drives the rotor shalt using a portion of the second rotational energy when the aircraft engine is cooling down in a temperature gradient in the casing;
the casing comprises trapped air creating the temperature gradient perpendicular to a longitudinal axis of the rotor shaft, and
the portion of the second rotational energy driving the rotor shaft reduces or prevents thermal bowing of the rotor shalt in the temperature gradient.

2. The apparatus of claim 1 , wherein the transmission comprises:
a transmission shaft connecting a gearbox to the rotor shaft;
the gearbox connected to a first motor and a first generator;
the first motor connected to a second generator;
the first generator connected to a second motor; and
wherein:
the first generator converts a portion of the first rotational energy of the rotor shaft into first electrical energy when the transmission and the gearbox transfer the first rotational energy to the first generator,
the second motor drives the flywheel when powered using the first electrical energy, thereby generating the second rotational energy in the flywheel,
the second generator converts a portion the second rotational energy into second electrical energy, when the second generator is driven by the flywheel, and
the first motor drives the rotor shaft when powered using the second electrical energy.

3. An aircraft comprising:
an aircraft engine including a rotor shaft, wherein the rotor shaft is inside a casing;
a flywheel;
a transmission connecting the rotor shaft and the flywheel, wherein;
second rotational energy in the flywheel is generated from first rotational energy of the rotor shaft transmitted to the flywheel through the transmission,
after shutdown of the aircraft engine, the transmission drives the rotor shaft using a portion of the second rotational energy when the aircraft engine is cooling down in a temperature gradient in the casing;
the casing comprises trapped air creating the temperature gradient perpendicular to a longitudinal axis of the rotor shaft, and
the portion of the second rotational energy driving the rotor shaft reduces or prevents thermal bowing of the rotor shaft in the temperature gradient and;
further comprising:
a computer connected to an electrical system; and
wherein the transmission includes:
a first transmission connected to a gearbox;
the gearbox connected to a first generator;
the first generator connected to a motor;
a second transmission connecting the motor to the flywheel; and
a second generator connected to the flywheel; and
wherein:
the first generator converts a portion of the first rotational energy of the rotor shaft into first electrical energy when the first transmission and the gearbox transfer the first rotational energy of the rotor shaft to the first generator,
the motor drives the flywheel when powered using the first electrical energy, thereby generating the second rotational energy in the flywheel,
the second generator converts a portion the second rotational energy into second electrical energy powering the electrical system during times of peak electrical loading of the electrical system, when the second generator is driven by the flywheel, and
the computer reduces fuel consumption in the aircraft engine engine as compared to when the aircraft engine engine is used to power the electrical system during the times of peak electrical loading without the flywheel.

4. An apparatus, comprising:
a gas turbine engine having a rotor shaft;
a flywheel; and
a first transmission connecting the rotor shaft to a gearbox, wherein:
the flywheel is connected to the gearbox, or
the gearbox is connected to a first generator, the first generator is connected to a first motor, a second transmission connects the flywheel to the first motor, and a third transmission connects the flywheel to a second generator; and

an electrical system connected to the second generator; wherein:
flywheel rotational energy in the flywheel is generated from rotational energy of the rotor shaft transmitted to the flywheel using the first transmission;
the second generator converts a portion of the flywheel rotational energy into second electrical energy, and
the second electrical energy powers the electrical system powering air conditioning on an aircraft, or powering cabin pressurization on the aircraft, or powering the air conditioning and the cabin pressurization.

5. The apparatus of claim 4 , wherein:
the gas turbine engine is inside a casing, and
the gearbox is attached to the casing.

6. The apparatus of claim 5 , wherein:
the casing comprises trapped air creating a temperature gradient perpendicular to a longitudinal axis of the rotor shaft, and
the first transmission transmits a portion of the flywheel rotational energy from the flywheel to the rotor shaft when the rotor shaft is cooling down in the temperature gradient, thereby reducing or preventing thermal bowing of the rotor shaft in the temperature gradient.

7. The apparatus of claim 4 , wherein:
the first transmission transmits the rotational energy of the rotor shaft to the first generator,
the first generator converts the rotational energy into first electrical energy, and
the first electrical energy powers the first motor driving the flywheel, thereby transferring a portion of the rotational energy to the flywheel and generating the flywheel rotational energy.

8. The apparatus of claim 7 , further comprising:
a second motor connected to the gearbox and the second generator; and
a casing, wherein the gas turbine engine is inside the casing and the casing comprises trapped air creating a temperature gradient perpendicular to a longitudinal axis of the rotor shaft, wherein:
the second generator converts a portion of the flywheel rotational energy into the second electrical energy powering the second motor, and
the second motor drives the rotor shaft, using the second electrical energy,

when the rotor shaft is cooling down in the temperature gradient, thereby reducing or preventing thermal bowing of the rotor shaft in the temperature gradient.

9. An aircraft comprising the apparatus of claim 7 , the aircraft further comprising:
a computer connected to the gas turbine engine, wherein:
the second generator converts a portion of the flywheel rotational energy into the second electrical energy powering the electrical system during times of peak electrical loading of the electrical system, and
the computer reduces fuel consumption in the gas turbine engine as compared to when the gas turbine engine is used to power the electrical system during the times of peak electrical loading without the flywheel.

10. An aircraft comprising the apparatus of claim 4 , further comprising:
an energy storage device connected to the second generator; wherein
the energy storage device stores the second electrical energy.

11. The apparatus of claim 4 , further comprising:
a casing housing the gas turbine engine;
an engine strut attached the gas turbine engine; and
a housing containing the flywheel, the first motor, and the second generator, wherein the housing is attached to the casing or the engine strut.

12. An aircraft comprising the apparatus of claim

Assignees

• Boeing Co

Inventors

• Jackowski Jason J
• Karnofski Kent E

Classifications

• F05D2260/43

  in the form of rotational kinetic energy, e.g. in flywheels · CPC title

• Y02T50/672

  Cross-Sectional Technologies · mapped topic

• F02C3/107

  with two or more rotors connected by power transmission · CPC title

• F02C9/26

  Control of fuel supply (F02C9/48 takes precedence; fuel valves F02C7/232) · CPC title

• F05D2260/941

  particularly aimed at mechanical or thermal stress reduction · CPC title