BLADE RETAINING CLIP

Abstract

A blade retaining clip and a blade assembly for axially securing a root portion of a blade component within an axially extending slot of a rotating disk. The blade retaining clip includes a shank portion, a first end portion and a second end portion. The shank portion includes an axial downwardly curved profile. The first end portion and the second end portion are integrally formed at opposed ends of the shank portion. The first end portion and the second end portion are configured to secure the root portion of the blade component within the axially extending slot of the rotating disk. The axial downward curvature of the shank portion minimized operating stresses at the first end portion and the second end portion and subsequent failure of the blade retaining clip.

Description

TECHNICAL FIELD

The present invention generally relates to turbine engine rotor assemblies and more particularly to a blade retaining clip that locks a turbine blade to a rotor disk or hub that carries the blade.

BACKGROUND

Turbine engines are used as the primary power source for many types of aircraft. The engines are also auxiliary power sources that drive air compressors, hydraulic pumps, and industrial gas turbine (IGT) power generation. Further, the power from turbine engines is used for stationary power supplies such as backup electrical generators for hospitals and the like.

Most turbine engines generally follow the same basic power generation procedure. Compressed air generated by axial and/or radial compressors is mixed with fuel and burned, and the expanding hot combustion gases are directed against stationary turbine vanes in the engine. The vanes turn the high velocity gas flow partially sideways to impinge on a plurality of turbine blades mounted on a rotatable turbine disk. The force of the impinging gas causes the turbine disk to spin at high speed. Jet propulsion engines use the power created by the rotating turbine disk to draw more air into the engine, and the high velocity combustion gas is passed out of the gas turbine aft end to create forward thrust. Other engines use this power to turn one or more propellers, fans, electrical generators, or other devices.

In a typical turbine engine, the rotating turbine disk includes a means for securing the plurality of blades to the disk. In general, a plurality of slots are formed about the periphery of the rotating turbine disk into which a root portion of a single turbine blade is inserted. Currently, turbine blades are often secured within the rotating turbine disk slots using retaining clips that are fabricated using a stamping process. One particular design for the blade retaining clip includes a substantially linear shank portion having an upwardly curved profile between opposing end portions. A first end portion of the blade retaining clip is pre-bent during fabrication. The clip is positioned within the turbine disk slot to hold the turbine blade therein. After positioning, the turbine blade is inserted into the disk and the second end portion of the clip is bent during final rotor assembly, thereby securing the turbine blade within the turbine disk slot. During operation of the turbine disk, a force is created upon the linear shank portion of the blade retaining clip, forcing it in a downward direction relative to the upward curvature of the shank profile and forcing a corresponding movement of the first and second end portions inward toward the rotor, potentially causing large axial loads where the two end portions engage the rotor and associated, undesirable operating stresses in the curved regions of the two end portions.

It should thus be appreciated from the above that it would be desirable to provide a blade retaining clip for the securement of a blade component within a rotating disk that is configured to prevent undesirable operating stresses in the end portions of the blade retaining clip. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.

BRIEF SUMMARY

The present invention provides a blade retaining clip for the securement of a blade component within a rotating disk that is configured to prevent the generation of operating stresses at the end portions of the blade retaining clip, resulting in possible failure of the blade retaining clip.

In one embodiment, and by way of example only, provided is a blade retaining clip for axially securing a root portion of a blade within an axially extending slot of a rotating disk. The blade retaining clip comprising: an elongate shank portion having a length at least equal to the axially extending slot of the rotating disk; and a first end portion and a second end portion, integrally formed at opposed ends of the elongate shank portion, the first end portion and the second end portion extending upwardly from the elongate shank portion and configured to secure the root portion of the blade within the axially extending slot of the rotating disk. The elongate shank portion having an axial downwardly curved profile.

In yet another embodiment, and by way of example only, provided is a blade retaining clip for axially securing a root portion of a blade within an axially extending slot of a rotating disk. The blade retaining clip comprising: an elongate shank having a substantially rod-like shape and a length at least equal to the axially extending slot of the rotating disk; and a first end portion and a second end portion, integrally formed at opposed ends of the elongate shank, the first end portion and the second end portion extending upwardly from the elongate shank portion and configured to include a plurality of retention stops to secure the blade within the axially extending slot of the rotating disk. The elongate shank portion having an axial downwardly curved profile.

In still another embodiment, and by way of example only, provided is a blade assembly for a turbine engine comprising: a rotating disk including a plurality of axially extending slots formed about a periphery of the rotating disk; an annular array of blades extending radially outwardly from the rotating disk, each of the blades including a root portion and an airfoil portion, the root portion of each blade positioned in one of the plurality of axially extending slots; and a plurality of blade retaining clips, one of the plurality of blade retaining clips positioned within each of the plurality of axially extending slots and providing radial retention of the each of the blades of the annular array of blades. Each of the plurality of blade retaining clips comprising: an elongate shank having a substantially rod-like shape, a length at least equal to an axially extending slot of the rotating disk, and an axial downwardly curved profile; and a first end portion and a second end portion, integrally formed at opposed ends of the elongate shank, the first end portion and the second end portion extending upwardly from the elongate shank portion and configured to secure a blade of the annular array of blades within an axially extending slot of the plurality of axially extending slots of the rotating disk.

Other independent features and advantages of the preferred methods will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified is a perspective view of an exemplary turbine engine;

FIG. 2 is a close up cross-section side view of the compressor, combustor, turbine, and exhaust sections of the exemplary gas turbine engine depicted in FIG. 1;

FIG. 3 is a simplified top view of a blade retaining clip for securing a blade within a rotating disk;

FIG. 4 is a simplified cross-sectional view of the blade retaining clip of FIG. 3;

FIG. 5 is a side sectional view of the blade retaining clip of FIGS. 3 and 4 positioned relative to a blade and a rotating disk; and

FIG. 6 is an orthogonal view of the blade retaining clip of FIGS. 3-and 4 positioned relative to a blade and a rotating disk.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

Before proceeding with a detailed description, it is to be appreciated that the described embodiment is not limited to use in conjunction with a particular type of turbine engine, or even for use in conjunction with a rotor assembly of a turbine engine. Thus, although the present embodiment is, for convenience of explanation, depicted and described as being implemented in a rotor assembly included within a turbine jet engine, it will be appreciated that it can be implemented in various other types of systems that include blade assemblies including a rotating disk and the need to secure blades to the rotating disk.

Referring now to FIGS. 1 and 2, an exemplary embodiment of a turbofan gas turbine jet engine 100 is depicted in FIG. 1 and includes an intake section 102, a compressor section 104, a combustion section 106, a turbine section 108, and an exhaust section 110. In FIG. 1, only half the structure is shown, it being substantially rotationally symmetric about a centerline and axis of rotation 101. FIG. 2 illustrates a close up cross-section side view of the compressor 104, combustor 106, turbine 108 and exhaust sections 110 of the exemplary gas turbine engine 100 depicted in FIG. 1. As best illustrated in FIG. 1, the intake section 102 includes a fan 112, which is mounted in a fan case 114. The fan 112 draws air into the intake section 102 and accelerates it. A fraction of the accelerated air exhausted from the fan 112 is directed through a bypass section 116 disposed between the fan case 114 and an engine cowl 118, and provides a forward thrust. The remaining fraction of air exhausted from the fan 112 is directed into the compressor section 104.

The compressor section 104 includes two compressor stages; an intermediate pressure compressor 120 and a high pressure compressor 122 interconnected by a rotary shaft 121 and a secondary cooling airflow system. The rotary shaft 121 interconnects the intermediate pressure compressor 120 and the high pressure compressor 122 in torque transmitting relationship. The intermediate pressure compressor 120 raises the pressure of the air directed into it from the fan 112, and directs the compressed air into the high pressure compressor 122. As best illustrated in FIG. 2, the intermediate pressure compressor 120 includes multiple stages, each including a rotor 130 and a stator 132. Each of the rotors 130 has a plurality of rotor blades 134. As the rotors 130 rotate, the plurality of rotor blades 134 force air through each of the stators 132 in a subsequent stage.

The high pressure compressor 122, in the depicted embodiment, includes a high pressure diffuser case 140 and a rotationally mounted high pressure impeller 144. The high pressure diffuser case 140 couples the intermediate pressure compressor 120 to the high pressure compressor 122 and directs exhausted air into the high pressure impeller 144. The high pressure impeller 144 has a plurality of vanes 146 extending there from that accelerate and compress the air. The high pressure impeller 144 compresses the air still further, and directs the high pressure air into the combustion section 106.

In the combustion section 106, which includes a combustor 124, the high pressure air is mixed with fuel and combusted. The combustor 124 receives the high pressure air from the compressor section 104 and mixes it with fuel to generate combusted air. The combusted air is then directed into the turbine section 108.

In this particular example, the turbine section 108 includes three turbines disposed in axial series flow, although it should be understood that any number of turbines may be included according to design specifics. More specifically, FIG. 1 depicts a high pressure turbine 150, an intermediate pressure turbine 152, and a low pressure turbine 154. Propulsion gas turbine engines may comprise only a high pressure turbine and a low pressure turbine. The expanding combusted air from the combustion section 106 expands through each turbine, causing it to rotate. More specifically, the hot combustion gases generated by the combustor 124 are directed against the stationary turbine vanes 158. The stationary turbine vanes 158 turn the high velocity gas flow partially sideways to impinge on a plurality of turbine blades 160 mounted on rotatable turbine disks 162 in each of the turbines 150, 152 and 154. The force of the impinging gas causes the rotatable turbine disks 162 to spin at high speed. The air is then exhausted through a propulsion nozzle 164 disposed in the exhaust section 110, providing addition forward thrust. As the turbines 150, 152 and 154 rotate, each drives equipment in the engine 100 via concentrically disposed shafts or spools as best seen in FIG. 1.

For the purposes of this disclosure, the blade retaining clip disclosed herein may be used with numerous types of blade assemblies, including any of those described above. More particularly, the blade retaining clip disclosed herein may be used in conjunction with the previously described components: (i) the fan assembly 112; (ii) the intermediate pressure compressor 120 and the high pressure compressor 122, and more particularly the securing of the plurality of rotor blades 134 to the rotors 130; and (iii) the high pressure turbine 150, the intermediate pressure turbine 152, and the low pressure turbine 154, and more particularly the securing of the plurality of turbine blades 160 to the rotatable turbine disks 162.

Referring now to FIGS. 3 and 4, illustrated is a top and cross-sectional view, respectively, of a blade retaining clip 200. As will be described presently, the blade retaining clip 200 aids in securing a plurality of blade components to a rotating disk such as those previously described. The blade retaining clip 200 is generally linear or rod-like in shape and includes an integrally formed first end portion 202 and an integrally formed second end portion 204 spaced a distance apart and connected by an elongate shank portion 206, as best seen in FIG. 4. In this particular embodiment, the first end portion 202 and the second end portion 204 are illustrated as being substantially t-shaped, although alternative shaped end portions 202 and 204 are anticipated herein by this disclosure. Some non-limiting examples of alternative shapes, include fan-shaped, pad shaped, or the like. As best illustrated in FIG. 4, the elongate shank portion 206 has a downwardly curved profile relative to the horizontal axis, referenced 208. More particularly, the elongate shank portion 206 is curved in a downward direction a distance “x” relative to a horizontal axis 208, where “x” is dependent upon the overall rotating disk design, and blade design. In this preferred embodiment, the elongate shank portion 206 has a degree of curvature approximately 0.005 to 0.025 inches relative to the axis 208 of the elongate shank portion 206. The blade retaining clip 200 differs from traditional retaining clip designs in that it incorporates this downward curved profile of the elongate shank portion 206 instead of an upward curve. As will be described herein, when the blade retaining clip 200 is properly positioned to secure a blade component within the rotating disk this direction and degree of curvature will aid in the securement of the blade component and reduce the operating stresses generated at the first end portion 202 and the second end portion 204.

The blade retaining clip 200 is preferably formed by well known sheet metal stamping techniques. As best illustrated in FIG. 3, during fabrication of the blade retaining clip 200, at least one of the first end portion 202 and the second end portion 204 is pre-bent on a die to create a substantially t-shaped retention stop 210. The retention stop 210 will serve to retain the blade component described herein. The remaining first end portion 202 or second end portion 204 remains in a straight, or unbent, state until final positioning of the blade component within the rotating disk slot and positioning of the blade retaining clip 200. Subsequent to positioning of the blade retaining clip 200 relative to the blade component and the rotating disk, the remaining unbent end portion 202 or 204 is then manually bent in a similar direction to the previous pre-bent end portion 202 or 204, to form a second retention stop 212 as best illustrated in FIG. 4.

Referring now to FIGS. 5 and 6, illustrated in simplified cross-sectional view, and orthogonal view, respectively, is a blade assembly 250, including the blade retaining clip 200 of FIGS. 3 and 4, positioned to secure each blade of an annular array of blades in a rotating disk. More specifically, illustrated is a portion of a blade 220 configured to extend radially outwardly from a rotating disk 230. The blade 220 comprises an airfoil portion 222 and a root portion 224. In this particular embodiment, the root portion 224 includes a retainer slot 226. The retainer slot 226 is of a corresponding dimension to provide for the positioning therein of the blade retaining clip 200 during operation. More specifically, during rotational operation, rotational forces cause the blade retaining clip 200 to flex in an upward direction, causing the downwardly curved profile of the elongate shank portion 206 (FIG. 4) to move upward into the retainer slot 226. This movement of the elongate shank portion 206 minimizes operational stresses on the first end portion 202 and the second end portion 204.

The rotating disk 230 includes a plurality of axially extending slots 232 formed about a periphery of the rotating disk 230 and of corresponding cross-sectional configuration to receive the root portion 224 of the blade 220. The axial retention of each root portion 224 into a corresponding slot 232 is provided by the blade retaining clip 200. The axial dimension of each of the axially extending slots 232 is approximately equal to the length of the elongate shank portion 206 of the blade retaining clip 200. The blade retaining clip 200 is positioned within the slot 232 of the disk 230 prior to insertion of the blade 220, such that the end portion 204 that was not previously bent protrudes from one end of the slot 232. Next, the blade 220 is inserted into the disk 230, and once the blade root portion 224 is properly positioned, the unbent end portion 204 is bent in an upward direction as previously described, and toward the root portion 224 to form the retention stop 212, thus securing the blade 220 within the rotating disk 230.

The blade retaining clip 200 described herein thus provides an improved means for providing axial securement of a root portion 224 of a blade 220 in a retaining slot 232 of a rotating disk 230. The blade retaining clip 200 utilizes an elongate shank portion 206 including a downwardly curved profile to offset operational stresses exerted upon the end portions 202 and 204 of the blade retaining clip 200.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A blade retaining clip for axially securing a root portion of a blade within an axially extending slot of a rotating disk comprising:

an elongate shank portion having a length at least equal to the axially extending slot of the rotating disk; and

a first end portion and a second end portion, integrally formed at opposed ends of the elongate shank portion, the first end portion and the second end portion extending upwardly from the elongate shank portion and configured to secure the root portion of the blade within the axially extending slot of the rotating disk,

wherein the elongate shank portion has an axial downwardly curved profile.

2. A blade retaining clip as claimed in claim 1, wherein the blade retaining clip is formed of a stamped sheet metal.

3. A blade retaining clip as claimed in claim 1, wherein the elongate shank portion has a substantially rod-like shape.

4. A blade retaining clip as claimed in claim 1, wherein the first end portion is pre-bent to secure the blade within the axially extending slot of the rotating disk.

5. A blade retaining clip as claimed in claim 4, wherein the second end portion is straight and bent during assembly of the blade within the axially extending slot of the rotating disk.

6. A blade retaining clip as claimed in claim 1, wherein the axial downwardly curved profile of the elongate shank portion includes a degree of curvature sufficient to offset operating stresses to the first end portion and the second end portion.

7. A blade retaining clip as claimed in claim 1, wherein the degree of curvature is 0.005 to 0.025 inches relative to an axis of the elongate shank portion.

8. A blade retaining clip as claimed in claim 1, wherein the elongate shank portion is configured to flex in an upwardly direction to offset operating stresses to the first end portion and the second end portion.

9. A blade retaining clip for axially securing a root portion of a blade within an axially extending slot of a rotating disk comprising:

an elongate shank having a substantially rod-like shape and a length at least equal to the axially extending slot of the rotating disk; and

a first end portion and a second end portion, integrally formed at opposed ends of the elongate shank, the first end portion and the second end portion extending upwardly from the elongate shank portion and configured to include a plurality of retention stops to secure the blade within the axially extending slot of the rotating disk,

wherein the elongate shank portion has an axial downwardly curved profile.

10. A blade retaining clip as claimed in claim 9, wherein the first end portion and the second end portion are t-shaped.

11. A blade retaining clip as claimed in claim 9, wherein the first end portion and the second end portion are configured to bend during assembly of the blade within the axially extending slot of the rotating disk.

12. A blade retaining clip as claimed in claim 9, wherein the blade retaining clip is formed of a stamped sheet metal.

13. A blade retaining clip as claimed in claim 9, wherein the axial downwardly curved profile of the elongate shank includes a degree of curvature sufficient to offset operating stresses to the first end portion and the second end portion.

14. A blade retaining clip as claimed in claim 9, wherein the degree of curvature is 0.005 to 0.025 inches relative to an axis of the elongate shank.

15. A blade assembly for a turbine engine comprising:

a rotating disk including a plurality of axially extending slots formed about a periphery of the rotating disk;

an annular array of blades extending radially outwardly from the rotating disk, each of the blades including a root portion and an airfoil portion, the root portion of each blade positioned in one of the plurality of axially extending slots; and

a plurality of blade retaining clips, one of the plurality of blade retaining clips positioned within each of the plurality of axially extending slots and providing radial retention of the each of the blades of the annular array of blades, each of the plurality of blade retaining clips comprising: an elongate shank having a substantially rod-like shape, a length at least equal to an axially extending slot of the rotating disk, and an axial downwardly curved profile; and a first end portion and a second end portion, integrally formed at opposed ends of the elongate shank, the first end portion and the second end portion extending upwardly from the elongate shank portion and configured to secure a blade of the annular array of blades within an axially extending slot of the plurality of axially extending slots of the rotating disk.

16. A blade assembly as claimed in claim 15, wherein the rotating disk is a turbine disk including a plurality of turbine blades radially extending therefrom.

17. A blade assembly as claimed in claim 15, wherein the plurality of blade retaining clips are formed of a stamped sheet metal.

18. A blade assembly as claimed in claim 15, wherein the first end portion is pre-bent to secure the blade within the axially extending slot of the rotating disk and the second end portion is bent during assembly of the blade within the axially extending slot of the rotating disk.

19. A blade assembly as claimed in claim 15 wherein the root portion of each of the blades includes a retainer slot formed therein.

20. A blade assembly as claimed in claim 15, wherein the axial downwardly curved profile includes a degree of curvature sufficient to offset operating stresses to the first end portion and the second end portion.