System for braking a low pressure spool in a gas turbine engine

Patent metadata

Field	Value
Publication number	US-10837312-B2
Application number	US-201514633565-A
Country	US
Kind code	B2
Filing date	Feb 27, 2015
Priority date	Feb 27, 2015
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

A braking system for the low pressure spool of a gas turbine engine includes a braking assembly connected to the low pressure spool and reversibly configurable between an actuated state and an unactuated state. The braking assembly in the unactuated state allows rotation of the low pressure spool without interference. The braking assembly in the actuated state applies a force opposing the rotation of the low pressure spool. A method of controlling the speed of rotation of a low pressure spool and a method of controlling the speed of rotation of low and high pressure spools are also discussed.

First claim

The invention claimed is:

1. A gas turbine engine comprising:
a low pressure spool and a high pressure spool rotating independently from one another;
a reduction gearbox connected to a low pressure shaft of the low pressure spool for transmitting a speed of rotation to an output shaft or a propeller shaft; and
a braking assembly connected to the low pressure spool by being directly connected to a gear of the reduction gearbox, the braking assembly being reversibly configurable between an actuated state and an unactuated state, the braking assembly in the unactuated state allowing rotation of the low pressure spool without interference between the braking assembly and the low pressure spool,
wherein the braking assembly includes a movable plate movable to frictionally engage a pad connected to the low pressure spool when the braking assembly is in the actuated state, the plate being disposed away from the pad when the braking assembly is in the unactuated state, and/or
wherein the braking assembly includes a static plate disposed in proximity of, spaced apart from and parallel with a surface of a web of the gear of the gearbox, a fluid being injected between the static plate and the surface when the braking assembly is in the actuated state,
the braking assembly in the actuated state applying a hydraulic friction force directly on the web of the gear and/or a friction force on the low pressure spool, the hydraulic friction force and/or the friction force opposing the rotation of the low pressure spool, the braking assembly being operatively disengaged from the high pressure spool in both of the actuated state and the unactuated state.

2. The gas turbine engine of claim 1 , further comprising a control unit connected to the braking assembly and selectively configuring the braking assembly between the actuated state and the unactuated state.

3. The gas turbine engine of claim 2 , further comprising a database in communication with the control unit, the database including at least one threshold value of at least one parameter indicative of a speed of rotation of the low pressure spool, the control unit configuring the state of the braking assembly based on a difference between a measured value of the at least one parameter and the at least one threshold value.

4. The gas turbine engine of claim 1 , wherein the braking assembly further includes a magnetic assembly including complementary magnet and coil relatively disposed one around the other, one of the magnet and the coil being connected to the low pressure spool such as to rotate therewith, the coil being energized when the braking assembly is in the actuated state to create a magnetic force opposing the rotation of the low pressure spool through interaction with the magnet.

5. The gas turbine engine of claim 4 , further comprising an energy storage medium connected to the magnetic assembly, the energy storage medium recuperating energy produced by an interaction between the magnet and coil when the braking assembly is in the actuated state.

6. The gas turbine engine of claim 1 , wherein the fluid is oil from a lubrication system of the gas turbine engine.

7. The gas turbine engine of claim 1 , further comprising:
at least one sensor measuring at least one parameter indicative of a speed of rotation of the low pressure spool;
a database including at least one threshold value of the at least one parameter; and
a control unit in communication in real time with the at least one sensor and the database, the control unit selectively configuring the braking assembly between the actuated state and the unactuated state based on the at least one threshold value stored in the database and the at least one parameter by the at least one sensor.

8. The gas turbine engine of claim 7 , wherein the braking assembly includes a magnetic assembly including complementary magnet and coil relatively disposed one around the other, one of the magnet and the coil being connected to the low pressure spool such as to rotate therewith, the coil being energized when the braking assembly is in the actuated state to create a magnetic force opposing the rotation of the low pressure spool.

9. The gas turbine engine of claim 7 , wherein the fluid is oil from a lubrication system of the gas turbine engine.

10. A method of controlling a speed of rotation of a low pressure spool in a gas turbine engine, the method comprising:
rotating the low pressure spool independently of a high pressure spool of the gas turbine engine;
determining if at least one parameter indicative of the speed of rotation of the low pressure spool has crossed at least one predetermined threshold value;
if the at least one parameter has crossed the predetermined threshold value, actuating a braking assembly by delivering fluid between a static plate and a surface of a web of a gear of a reduction gearbox connected to a low pressure shaft of the low pressure spool to apply a hydraulic friction force directly to the web of the gear of the reduction gearbox and/or by moving a non-rotating plate to frictionally engage a pad connected to the low pressure spool to create a friction force on the low pressure spool, the hydraulic friction force and/or the friction force opposing the rotation of the low pressure spool, the low pressure spool rotating independently of the high pressure spool independently of the force being applied.

11. The method of claim 10 , wherein determining if the at least one parameter has crossed the at least one predetermined threshold value comprises:
measuring the at least one parameter with at least one sensor;
receiving the measured at least one parameter with a control unit;
accessing the at least one predetermined threshold value of the at least one parameter stored in a database; and
comparing with the control unit the measured at least one parameter with the at least one predetermined threshold value from the database.

12. The method of claim 10 , wherein actuating the braking assembly further comprises creating a magnetic force opposing the rotation of the low pressure spool on the low pressure spool.

13. The method of claim 12 , wherein the creating of the magnetic force includes storing energy into an energy storage medium.

14. The method of claim 13 , comprising recuperating energy produced by an interaction between a magnet and a coil when the hydraulic friction force and/or the friction force is applied.

15. The method of claim 10 , wherein the delivering of the fluid includes delivering oil from a lubrication system of the gas turbine engine.

16. A method of controlling a speed of rotation of low and high pressure spools in a gas turbine engine, the method comprising:
maintaining the speed of rotation of the high pressure spool above a second threshold value by controlling a fuel flow of the gas turbine engine; and

maintaining the speed of rotation of the low pressure spool below a first threshold value by selectively applying a hydraulic friction force directly on a web of a gear of a reduction gearbox connected to a low pressure shaft of the low pressure spool by delivering fluid between a static plate and a surface of the web and/or applying a friction force on the low pressure spool by moving a non-rotating plate to frictionally engage a pad connected to the low pressure spool, while the low pressure spool rotates independently of the high pressure spool, the low pressure spool rotating independently of the high pressure spool independently of the force being applied.

17. The method of claim 16 , wherein the delivering of the fluid includes

Assignees

• Pratt & Whitney Canada

Inventors

• Gates Patrick
• Bibor Olivier

Classifications

• F05D2270/022

  to prevent underspeed · CPC title

• F05D2270/091

  in particular sudden load loss · CPC title

• F05D2270/023

  of different spools or shafts · CPC title

• F05D2270/021

  to prevent overspeed · CPC title

• F01D21/02

  Shutting-down responsive to overspeed · CPC title