GAS TURBINE ENGINE WITH INTERCOOLED COOLING AIR AND DUAL TOWERSHAFT ACCESSORY GEARBOX

• US 20180202368A1
• 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 10,995,673 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 25/12 Cooling
• CPC Class Codes: F02C 3/06 the compressor comprising only axial stages F02C3/10 takes precedence
• CPC Class Codes: F02C 7/185 Cooling means for reducing the temperature of the cooling air or gas
• 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 7/275 Mechanical drives
• 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 2260/4031 as in toothed gearing
• CPC Class Codes: F05D 2260/85 Starting
• CPC Class Codes: F16H 1/222 with non-parallel axes
• CPC Class Codes: H02K 7/116 with gears
• CPC Class Codes: H02K 7/1823 structurally associated with turbines or similar engines

Abstract

An exemplary gas turbine engine assembly includes a first spool having a first turbine operatively mounted to a first turbine shaft, and a second spool having a second turbine operatively mounted to a second turbine shaft. The first and second turbines are mounted for rotation about a common rotational axis within an engine static structure. The first and second turbine shafts are coaxial with one another. First and second towershafts are respectively coupled to the first and second turbine shafts. An accessory drive gearbox has a set of gears. A compressor is driven by the first towershaft. The engine assembly further includes a starter generator assembly, and a transmission coupling the starter generator assembly to the 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 compressor driven by the first towershaft;

a starter generator assembly; 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:

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; and

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.

7. The gas turbine engine assembly of claim 6, wherein the first clutch and the second clutch are one-way mechanical clutch devices.

8. The gas turbine engine assembly of claim 1, wherein the compressor is a boost compressor of an intercooled cooling air system.

9. The gas turbine engine assembly of claim 8, further comprising a compressor section having a downstream most end and a cooling air tap at a location spaced upstream from said downstream most end, wherein the cooling air tap is passed through at least one boost compressor and at least one heat exchanger, and then passed to a turbine section to cool the turbine section.

10. 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.

11. 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.

12. 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.

13. 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

driving a compressor through the accessory gearbox with the first towershaft once the engine is started.

14. The method of claim 13, further comprising decoupling the starter from the first spool once the first spool reaches an engine idle speed.

15. The method of claim 14, wherein the decoupling includes rotating the second towershaft at a speed greater than that of the starter.

16. The method of claim 13, wherein the compressor is a boost compressor of an intercooled cooling air system.

17. The method of claim 16, further comprising a compressor section having a downstream most end and a cooling air tap at a location spaced upstream from said downstream most end, wherein the cooling air tap is passed through at least one boost compressor and at least one heat exchanger, and then passed to a turbine section to cool the turbine section.

18. The method of claim 13, 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.

19. The method of claim 18, 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.

20. The method of claim 13, further comprising driving a fan through a speed reduction device with a shaft of the second spool.