FLEXIBLE COUPLING FOR GEARED TURBINE ENGINE

• US 20180128186A1
• Filed: 01/05/2018
• Published: 05/10/2018
• Est. Priority Date: 03/12/2013
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Sheridan, William G., Otto, John R.
• Granted Patent: US 10,087,851 B2
• Time in Patent Office: Days
• CPC Class Codes: F02C 7/06 Arrangements of bearings bearings F16C; Lubricating of turbo machines F01D25/18; of machines or engines in general F01M
• CPC Class Codes: F02C 7/20 Mounting or supporting of plant; Accommodating heat expansion or creep
• 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 2260/403 through the shape of the drive components
• CPC Class Codes: F05D 2260/40311 of the epicyclical, planetary or differential type
• CPC Class Codes: F05D 2260/96 Preventing, counteracting or reducing vibration or noise

Abstract

A gas turbine engine includes a fan shaft arranged along an engine central axis, a frame supporting the fan shaft, a gear system rotatably coupled with the fan shaft, and a flexible coupling at least partially supporting the gear system. The flexible coupling defines, with respect to the engine central axis, a torsional stiffness TS and a lateral stiffness LS such that a ratio of TS/LS is greater than or equal to about 2.0 to reduce loads on the gear system from misalignment of the gear system with respect to the engine central axis.

Claims

1. A gas turbine engine comprising:

a fan shaft arranged along an engine central axis;

a frame supporting the fan shaft, the frame defining a frame lateral stiffness;

a gear system rotatably coupled to the fan shaft, the gear system having a gear reduction ratio that is greater than 2.3; and

a first, non-rotatable flexible coupling and a second, rotatable flexible coupling supporting the gear system, the first flexible coupling and the second flexible coupling being subject to, with respect to the engine central axis, parallel offset guided end motion,

the second flexible coupling having a Stiffness D that is torsional stiffness under the parallel offset guided end motion, and the second flexible coupling has a ratio of frame lateral stiffness to Stiffness D that is in a range of 2 to 100.

2. The gas turbine engine as recited in claim 1, wherein the gear system includes a sun gear in meshed engagement with multiple intermediate gears that are rotatably mounted on bearings in a non-rotatable carrier, each intermediate gear is in meshed engagement with a rotatable ring gear, the sun gear is rotatably coupled to the fan shaft, and the first, non-rotatable flexible coupling is coupled with the non-rotatable carrier.

3. The gas turbine engine as recited in claim 2, wherein the gear system is coupled through an input shaft to a low pressure turbine, the low pressure turbine having a pressure ratio of greater than 5.

4. The gas turbine engine as recited in claim 3, wherein the fan has a fan pressure ratio of less than 1.45.

5. The gas turbine engine as recited in claim 1, wherein the gear system includes a sun gear in meshed engagement with multiple intermediate gears that are rotatably mounted on bearings in a rotatable carrier, each intermediate gear is in meshed engagement with a non-rotatable ring gear, the sun gear is rotatably coupled to the fan shaft, and the first, non-rotatable flexible coupling is coupled with the non-rotatable ring gear.

6. The gas turbine engine as recited in claim 5, wherein the gear system is coupled through an input shaft to a low pressure turbine, the low pressure turbine having a pressure ratio of greater than 5.

7. The gas turbine engine as recited in claim 6, wherein the fan has a fan pressure ratio of less than 1.45.

8. A gas turbine engine comprising:

a fan;

a fan shaft coupled with the fan and arranged along an engine central axis;

an input shaft;

a high pressure turbine and a low pressure turbine, the low pressure turbine having a pressure ratio of greater than 5;

a frame supporting the fan shaft, the frame defining a frame lateral stiffness;

a gear system rotatably coupled with the fan shaft and also rotatably coupled with the low pressure turbine through the input shaft; and

a first, non-rotatable flexible coupling and a second, rotatable flexible coupling supporting the gear system, the first flexible coupling and the second flexible coupling being subject to, with respect to the engine central axis, parallel offset guided end motion,

the second flexible coupling having a Stiffnesses D that is torsional stiffness under the parallel offset guided end motion, and the second flexible coupling has a ratio of frame lateral stiffness to Stiffness D that is in a range of 2 to 100.

9. The gas turbine engine as recited in claim 8, wherein the gear system includes a sun gear in meshed engagement with multiple intermediate gears that are rotatably mounted on bearings in a non-rotatable carrier, each intermediate gear is in meshed engagement with a rotatable ring gear, the sun gear is rotatably coupled to the fan shaft, and the first, non-rotatable flexible coupling is coupled with the non-rotatable carrier.

10. The gas turbine engine as recited in claim 9, wherein the gear system has a gear reduction ratio of greater than 2.3.

11. The gas turbine engine as recited in claim 10, wherein the fan has a fan pressure ratio of less than 1.45.

12. The gas turbine engine as recited in claim 8, wherein the gear system includes a sun gear in meshed engagement with multiple intermediate gears that are rotatably mounted on bearings in a rotatable carrier, each intermediate gear is in meshed engagement with a non-rotatable ring gear, the sun gear is rotatably coupled to the fan shaft, and the first, non-rotatable flexible coupling is coupled with the non-rotatable ring gear.

13. The gas turbine engine as recited in claim 12, wherein the gear system has a gear reduction ratio of greater than 2.3.

14. The gas turbine engine as recited in claim 13, wherein the fan has a fan pressure ratio of less than 1.45.

15. A gas turbine engine comprising:

a fan shaft arranged along an engine central axis;

a frame supporting the fan shaft, the frame defining a frame lateral stiffness;

a gear system rotatably coupled to the fan shaft, the gear system including a sun gear in meshed engagement with multiple intermediate gears that are rotatably mounted on bearings in a non-rotatable carrier, each intermediate gear in meshed engagement with a rotatable ring gear, and the sun gear rotatably coupled to the fan shaft; and

a first, non-rotatable flexible coupling and a second, rotatable flexible coupling supporting the gear system, the first flexible coupling and the second flexible coupling being subject to, with respect to the engine central axis, parallel offset guided end motion,

the second flexible coupling having a Stiffness D that is torsional stiffness under the parallel offset guided end motion, and the second flexible coupling has a ratio of frame lateral stiffness to Stiffness D that is in a range of 2 to 100.

16. The gas turbine engine as recited in claim 15, wherein the fan has a fan pressure ratio of less than 1.45.

17. The gas turbine engine as recited in claim 16, wherein the gear system is coupled through an input shaft to a low pressure turbine, the low pressure turbine having a pressure ratio of greater than 5.

18. The gas turbine engine as recited in claim 17, wherein the gear system has a gear reduction ratio of greater than 2.3.

19. The gas turbine engine as recited in claim 15, wherein the gear system is coupled through an input shaft to a low pressure turbine, the low pressure turbine having a pressure ratio of greater than 5.

20. The gas turbine engine as recited in claim 15, wherein the gear system has a gear reduction ratio of greater than 2.3.

21. A gas turbine engine comprising:

a fan shaft arranged along an engine central axis;

a frame supporting the fan shaft, the frame defining a frame lateral stiffness;

a gear system rotatably coupled to the fan shaft, the gear system including a sun gear in meshed engagement with multiple intermediate gears that are rotatably mounted on bearings in a rotatable carrier, each intermediate gear in meshed engagement with a non-rotatable ring gear, and the sun gear rotatably coupled to the fan shaft; and

a first, non-rotatable flexible coupling and a second, rotatable flexible coupling supporting the gear system, the first flexible coupling and the second flexible coupling being subject to, with respect to the engine central axis, parallel offset guided end motion,

the second flexible coupling having a Stiffness D that is torsional stiffness under the parallel offset guided end motion, and the second flexible coupling has a ratio of frame lateral stiffness to Stiffness D that is in a range of 2 to 100.

22. The gas turbine engine as recited in claim 21, wherein the fan has a fan pressure ratio of less than 1.45.

23. The gas turbine engine as recited in claim 22, wherein the gear system is coupled through an input shaft to a low pressure turbine, the low pressure turbine having a pressure ratio of greater than 5.

24. The gas turbine engine as recited in claim 23, wherein the gear system has a gear reduction ratio of greater than 2.3.

25. The gas turbine engine as recited in claim 21, wherein the gear system is coupled through an input shaft to a low pressure turbine, the low pressure turbine having a pressure ratio of greater than 5.

26. The gas turbine engine as recited in claim 21, wherein the gear system has a gear reduction ratio of greater than 2.3.