GAS TURBINE ENGINE DUAL TOWERSHAFT ACCESSORY GEARBOX AND STARTER GENERATOR ASSEMBLY

• US 20180202310A1
• Filed: 01/19/2017
• Published: 07/19/2018
• Est. Priority Date: 01/19/2017
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Suciu, Gabriel L., Duong, Hung, Zimmitti, Jonathan F., Sheridan, William G., McCune, Michael E., Merry, Brian
• Granted Patent: US 10,422,243 B2
• Time in Patent Office: Days
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F01D 15/12 Combinations with mechanical gearing driven by multiple engines F01D13/00
• CPC Class Codes: F01D 25/20 using lubrication pumps
• CPC Class Codes: F01D 5/06 Rotors for more than one axial stage, e.g. of drum or multiple disc type; Details thereof, e.g. shafts, shaft connections F01D5/022, F01D5/023 take precedence
• CPC Class Codes: F02C 7/268 Starting drives for the rotor , acting directly on the rotor of the gas turbine to be started
• CPC Class Codes: F02C 7/277 the starter being a separate turbine
• CPC Class Codes: F02C 7/32 Arrangement, mounting, or driving, of auxiliaries
• CPC Class Codes: F02C 7/36 Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user F02C3/107 - F02C3/13 and F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H
• CPC Class Codes: F05D 2220/32 in gas turbines
• CPC Class Codes: F05D 2240/60 Shafts
• CPC Class Codes: F05D 2260/4023 through a friction clutch
• CPC Class Codes: F05D 2260/4031 as in toothed gearing
• CPC Class Codes: F16H 3/30 with driving and driven shafts not coaxial

Abstract

An exemplary gas turbine engine assembly includes a transmission coupling a starter generator assembly to a first set of gears. The transmission is transitionable between a first mode where the starter generator assembly is driven at a first speed relative to the second towershaft, and a second mode where the starter generator assembly is driven at a different, second speed relative to the second towershaft.

Claims

1. A gas turbine engine assembly comprising:

a first spool having a first turbine operatively mounted to a first turbine shaft;

a second spool having a second turbine operatively mounted to a second turbine shaft, the first and second turbines mounted for rotation about a common rotational axis within an engine static structure, the first and second turbine shafts coaxial with one another;

first and second towershafts respectively coupled to the first and second turbine shafts;

an accessory drive gearbox with a set of gears;

a starter generator assembly;

a first clutch disposed between the first towershaft and the starter generator assembly, the first clutch configured to enable the starter generator assembly to drive the first spool through the accessory drive gearbox;

a second clutch disposed between the second towershaft and the starter generator assembly, the second clutch configured to enable the second spool to drive the starter generator assembly through the accessory drive gearbox; and

a transmission coupling the starter generator assembly to the first set of gears, the transmission transitionable between a first mode where the starter generator assembly is driven at a first speed relative to the second towershaft, and a second mode where the starter generator assembly is driven at a different, second speed relative to the second towershaft.

2. The gas turbine engine assembly of claim 1, wherein the first and second turbine shafts are outer and inner shafts, respectively, and the first and second turbines are high and low pressure turbines, respectively.

3. The gas turbine engine assembly of claim 2, wherein the first towershaft is configured to rotate at a higher speed than the second towershaft.

4. The gas turbine engine assembly of claim 1, wherein the transmission is further transitionable to a third mode where the starter generator assembly is driven at a different, third speed relative to the second towershaft.

5. The gas turbine engine assembly of claim 4, wherein the transmission is further transitionable to at least one fourth mode where the starter generator assembly is driven at a fourth speed relative to the second towershaft, the fourth speed different than each of the first, second, and third speeds.

6. The gas turbine engine assembly of claim 1, further comprising an oil pump, wherein the starter generator assembly is driven by the second towershaft at a first speed relative to the oil pump when the transmission in first mode, and the starter generator assembly is driven by the second towershaft at a different, second speed relative to the oil pump when the transmission is in the second mode.

7. The gas turbine engine assembly of claim 6, wherein the oil pump is configured to communicate oil to a geared architecture that drives a fan of the gas turbine engine at a lower speed than the second turbine shaft.

8. The gas turbine engine assembly of claim 1, further comprising a fan driven by a speed reduction device, wherein the speed reduction device is driven by the second turbine shaft.

9. The gas turbine engine assembly of claim 1, wherein the first clutch and the second clutch are one-way mechanical clutch devices.

10. The gas turbine engine assembly of claim 1, wherein the starter generator assembly comprises a first variable frequency generator and a second variable frequency generator.

11. The gas turbine engine assembly of claim 1, wherein the starter generator assembly comprises a first integrated drive generator and a second integrated drive generator.

12. A method of operating a gas turbine engine, comprising:

driving a first spool with a starter through a first towershaft and a first clutch to start the engine;

driving a starter generator assembly through an accessory gearbox through a second clutch with a second towershaft coupled to a second spool once the engine is started; and

decoupling the starter from the first spool once the first spool reaches an engine idle speed.

13. The method of claim 12, further comprising:

driving the starter generator through a transmission in a first mode so that the starter generator assembly is rotated at a first speed relative to the second towershaft; and

transitioning the transmission to a second mode so that the starter generator is driven by the second towershaft and rotated at a different, second speed relative to the second towershaft.

14. The method of claim 13, further comprising transitioning the transmission to a third mode;

and driving the transmission with the second towershaft to rotate the starter generator assembly at a different, third speed relative to the second towershaft.

15. The method of claim 13, further comprising driving an oil pump with the second towershaft when the starter generator is driven by the second towershaft through the transmission, the oil pump driven at a first speed relative the second towershaft when the transmission is in the first mode, and when the transmission is in the second mode.

16. The method of claim 15, further comprising supplying oil to from the oil pump to a geared architecture that drives a fan of the gas turbine engine at a lower speed than the second spool.

17. The method of claim 12, wherein the decoupling includes rotating the second towershaft at a speed greater than that of the starter.

18. The method of claim 12, further comprising driving a fan through a speed reduction device with a shaft of the second spool.

19. The method of claim 12, wherein the first clutch and the second clutch are one-way mechanical clutch devices.

20. The method of claim 12, wherein the starter generator assembly comprises a first variable frequency generator and a second variable frequency generator.