CURVIC SEAL FITTING AND BALANCE WEIGHT LOCATIONS

Abstract

Aspects of the disclosure are directed to a seal comprising: a first fitting configured to couple to a first disk, and a curvic joint including curvic teeth, where a first distance between the first fitting and the curvic teeth is equal to or greater than a first thickness of the first disk. In some embodiments, an engine comprises: a compressor disk, a turbine disk, and a seal including: a first fitting configured to couple to the turbine disk, a second fitting configured to couple to the compressor disk, and a curvic joint including curvic teeth, where a first axial distance between the first fitting and the curvic teeth is greater than or equal to a first radial thickness of the turbine disk.

Claims

1. A seal comprising: a first fitting configured to couple to a first disk; and a curvic joint including curvic teeth, wherein a first distance between the first fitting and the curvic teeth is equal to or greater than a first thickness of the first disk.

2. The seal of claim 1, further comprising: a second fitting configured to couple to a second disk, wherein a second distance between the second fitting and the curvic teeth is equal to or greater than a second thickness of the second disk.

3. The seal of claim 2, wherein the first fitting is a first interference fitting.

4. The seal of claim 3, wherein the second fitting is a second interference fitting.

5. The seal of claim 3, wherein the second fitting is a loose fitting.

6. The seal of claim 5, further comprising: a wire seal incorporated as part of the second fitting.

7. The seal of claim 1, further comprising: a balance weight.

8. The seal of claim 7, wherein the balance weight is substantially located in the same axial plane as the curvic joint.

9. The seal of claim 1, further comprising: an anti-rotation tab configured to couple to a slot of the first disk.

10. The seal of claim 1, wherein the first distance is less than three times the thickness of the first disk.

11. An engine comprising: a compressor disk; a turbine disk; and a seal including: a first fitting configured to couple to the turbine disk; a second fitting configured to couple to the compressor disk; and a curvic joint including curvic teeth, wherein a first axial distance between the first fitting and the curvic teeth is greater than or equal to a first radial thickness of the turbine disk.

12. The engine of claim 11, wherein a second axial distance between the second fitting and the curvic teeth is greater than or equal to a second radial thickness of the compressor disk.

13. The engine of claim 11, wherein at least one of the first fitting and the second fitting is an interference fitting.

14. The engine of claim 11, wherein one of the first fitting and the second fitting is an interference fitting and the other of the first fitting and the second fitting is a loose fitting.

15. The engine of claim 14, further comprising: a wire seal incorporated as part of the loose fitting.

16. The engine of claim 11, wherein the seal includes a balance weight.

17. The engine of claim 16, wherein the balance weight is substantially located in the same axial plane as the curvic joint.

18. The engine of claim 11, wherein the seal includes an anti-rotation tab configured to couple to a slot of the turbine disk.

19. The engine of claim 11, wherein the seal includes an anti-rotation tab configured to couple to a slot of the compressor disk.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. The drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0009] FIG. 1 is a side cutaway illustration of a geared turbine engine.

[0010] FIG. 2 illustrates a portion of a prior art engine incorporating a curvic seal and a balance weight.

[0011] FIG. 3 illustrates a portion of an engine in accordance with aspects of this disclosure.

[0012] FIG. 4 illustrates a plot of stress versus fitting distance in accordance with aspects of this disclosure.

[0013] FIGS. 5A-5B illustrate a tab of a seal coupled to a slot of a disk in accordance with aspects of this disclosure.

[0014] FIG. 6 illustrates a curvic interface between a first disk and a second disk in accordance with aspects of this disclosure.

[0015] FIG. 7 illustrates a seal incorporated as part of a curvic interface in accordance with aspects of this disclosure.

DETAILED DESCRIPTION

[0016] It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities.

[0017] In accordance with aspects of the disclosure, apparatuses, systems, and methods are directed to a curvic seal. The seal may be incorporated as part of one or more sections of an engine. The seal may include one or more snaps for coupling the seal to a compressor disk or a turbine disk. A location of a snap may be related to a dimension of the compressor disk or a dimension of the turbine disk. In some embodiments, a balance weight/flange may be incorporated in proximity to a curvic joint. In some embodiments, the seal may include a tab that mates with a slot in the compressor disk and/or a slot in the turbine disk to provide anti-rotation.

[0018] Aspects of the disclosure may be applied in connection with a gas turbine engine. FIG. 1 is a side cutaway illustration of a geared turbine engine 10. This turbine engine 10 extends along an axial centerline 12 between an upstream airflow inlet 14 and a downstream airflow exhaust 16. The turbine engine 10 includes a fan section 18, a compressor section 19, a combustor section 20 and a turbine section 21. The compressor section 19 includes a low pressure compressor (LPC) section 19A and a high pressure compressor (HPC) section 19B. The turbine section 21 includes a high pressure turbine (HPT) section 21A and a low pressure turbine (LPT) section 21B.

[0019] The engine sections 18-21 are arranged sequentially along the centerline 12 within an engine housing 22. Each of the engine sections 18-19B, 21A and 21B includes a respective rotor 24-28. Each of these rotors 24-28 includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s).

[0020] The fan rotor 24 is connected to a gear train 30, for example, through a fan shaft 32. The gear train 30 and the LPC rotor 25 are connected to and driven by the LPT rotor 28 through a low speed shaft 33. The HPC rotor 26 is connected to and driven by the HPT rotor 27 through a high speed shaft 34. The shafts 32-34 are rotatably supported by a plurality of bearings 36; e.g., rolling element and/or thrust bearings. Each of these bearings 36 is connected to the engine housing 22 by at least one stationary structure such as, for example, an annular support strut.

[0021] During operation, air enters the turbine engine 10 through the airflow inlet 14, and is directed through the fan section 18 and into a core gas path 38 and a bypass gas path 40. The air within the core gas path 38 may be referred to as “core air”. The air within the bypass gas path 40 may be referred to as “bypass air”. The core air is directed through the engine sections 19-21, and exits the turbine engine 10 through the airflow exhaust 16 to provide forward engine thrust. Within the combustor section 20, fuel is injected into a combustion chamber 42 and mixed with compressed core air. This fuel-core air mixture is ignited to power the turbine engine 10. The bypass air is directed through the bypass gas path 40 and out of the turbine engine 10 through a bypass nozzle 44 to provide additional forward engine thrust. This additional forward engine thrust may account for a majority (e.g., more than 70 percent) of total engine thrust. Alternatively, at least some of the bypass air may be directed out of the turbine engine 10 through a thrust reverser to provide reverse engine thrust.

[0022] FIG. 1 represents one possible configuration for an engine 10. Aspects of the disclosure may be applied in connection with other environments, including additional configurations for gas turbine engines. Aspects of the disclosure may be applied in connection with non-geared engines.

[0023] Referring to FIG. 3, a portion of an engine 300 is shown. The engine 300 may include a curvic seal 304 and a curvic joint 308 (which may include curvic teeth). The curvic joint 308 may interface to a compressor disk 312 and a turbine disk 316. The seal 304 may include a fitting 320 that may couple the seal 304 to the turbine disk 316. The seal 304 may include a fitting 324 that may couple the seal 304 to the compressor disk 312.

[0024] One or both of the fittings 320 and 324 may be implemented as interference fittings. One of the fittings 320 and 324 may be implemented as a loose fitting. To the extent that a loose fitting is used, a wire seal (e.g., the wire seal 228) may be incorporated as part of that loose fitting to reduce/minimize any leakage (e.g., the leakage 232) in a manner similar to that described above with respect to FIG. 2.

[0025] As shown in FIG. 3, the compressor disk 312 may have a thickness (e.g., a radial thickness) 312a. The turbine disk 316 may have a thickness (e.g., a radial thickness) 316a. The fitting 320 may be located a distance (e.g., an axial distance) 320a from the curvic joint/teeth 308. The fitting 324 may be located a distance (e.g., an axial distance) 324a from the curvic joint/teeth 308.

[0026] The distances 320a and 324a may be related to the thicknesses 316a and 312a, respectively. For example, and referring to FIG. 4, a plot 400 is depicted of stress (shown on the vertical axis) imposed on the teeth of the curvic joint 308 from an interference fit 320 versus distance (e.g., distance 320a or 324a) (shown on the horizontal axis).

[0027] As part of the plot 400, various values of the distance are depicted and expressed as a multiple of a “shell thickness”/“disk thickness” (e.g., thickness 316a or 312a), where the thickness is measured/specified within an axial span/profile of the seal. Similarly, various values of the stress are depicted and expressed relative to a reference value of the stress (e.g., 1.0 S) taken at a distance that is less than 1 shell thickness. For example, at a distance of one (1) shell thickness the stress may have a value expressed as the product of X and S, where X is less than 1.0. At a distance of two (2) shell thicknesses, the stress may have a value expressed as the product of Y and S, where Y is less than X. At a distance of three (3) shell thicknesses, the stress may have a value expressed as the product of Z and S, where Z is less than Y.

[0028] As reflected in FIG. 4, as the distance increases the stress imposed decreases. Moreover, due to the (exponential) profile/shape of the curve 404 associated with the plot 400, the rate at which the stress is reduced may decrease with each incremental unit (e.g., each incremental multiple of shell thickness) of distance that is used. In this respect, a trade-off may be made in a given application environment between the stress that the seal experiences and the overall distance/space that the seal consumes. It has been determined that an approximate distance of at least one shell thickness is desirable in most application environments. But for a few rare instances, it might not be worth using a distance greater than three shell thicknesses as the reduction in stress that is obtained is likely not worth the extra space that the seal consumes. In this respect, the distance may be provisioned to have a value within a range of one and three shell thicknesses in some embodiments.

[0029] Due to the distances 320a and 324a of the fittings 320 and 324 relative to the curvic joint 308 being substantially larger than in conventional seal designs, a balance weight/flange 336 may be substantially located in the same axial station/plane 340 as the curvic joint 308. As shown in FIG. 3, the balance weight 336 may be located on the seal 304.

[0030] Referring to FIG. 5A, the seal 304 may include one or more tabs (e.g., a tab 504a) that may be coupled to (e.g., seated within) one or more counterpart slots (e.g., slot 512) formed in the compressor disk 312. Together, the tab 504a and the slot 512 may provide an anti-rotation feature with respect to the seal 304. Referring to FIG. 5B, in some embodiments one or more slots (e.g., a slot 516) may be formed in the turbine disk 316 to provide for anti-rotation via a coupling of one or more counterpart tabs (e.g., tab 504b) of the seal 304 and the slot 516.

[0031] Referring to FIG. 6, a curvic interface between the compressor disk 312 and the turbine disk 316 is shown. For example, teeth 612 of the compressor disk 312 are shown as engaging teeth 616 of the turbine disk 316. In FIG. 7, the seal 304 is shown in proximity/relationship to the teeth 616.

[0032] Technical effects and benefits of this disclosure include a seal that has an enhanced lifetime relative to a conventional seal, where the useable lifetime of the seal is based on the stress that is imposed on the seal. A reduction in stress may be obtained by extending a distance between a curvic joint/teeth and a fitting of the seal, the fitting coupling the seal and a disk. In some embodiments, the location of a balance weight in the same axial plane as a curvic joint may provide an enhanced ability to correct imbalance at the curvic joint.

[0033] Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional in accordance with aspects of the disclosure. One or more features described in connection with a first embodiment may be combined with one or more features of one or more additional embodiments.