Anti-rotation nozzle sector and method for manufacturing such a sector

Abstract

A nozzle sector of an aircraft turbo-machine, including a hooking member (64) having a projection (70, 70a, 70b) radially extending towards the outside of the sector, a recess (72) being provided through at least one part of a distal end of the projection (70, 70a, 70b), the recess (72) being configured to accommodate a shoulder member (74) forming a stop for a surface of an adjacent sector (26).

Claims

1. A nozzle sector of an aircraft turbomachine, the nozzle sector including vanes, a hooking member and a shoulder member, the hooking member having a projection radially extending towards an outside of the sector relative to the vanes, the hooking member being configured to be secured to a casing radially surrounding the nozzle sector, wherein a recess is provided through at least one part of a distal end of the projection, the recess accommodating the shoulder member, wherein the shoulder member is configured to form an anti-rotation stop for a surface of a sealing sector axially adjacent to the nozzle sector, wherein the shoulder member is configured to be mounted and secured in the recess before assembling the nozzle sector in the turbomachine.

2. The nozzle sector according to claim 1, wherein the projection has a radial portion and an axial portion extending from a distal end of the radial portion, and wherein the recess is provided through at least one part of the axial portion.

3. The nozzle sector according to claim 1, wherein the shoulder member is secured in the recess by welding, crimping, or soldering.

4. The nozzle sector according to claim 1, wherein the shoulder member radially protrudes towards the inside of the distal end of the projection.

5. The nozzle sector of an aircraft turbomachine according to claim 1, wherein the shoulder member includes a first part and a second part, the first part having a width substantially identical to the recess, the second part having a width greater than the first part.

6. The nozzle sector according to claim 5, wherein the shoulder member comprises a contact surface which is in contact with an anti-rotation projection attached to the sealing sector, and wherein the contact surface is provided on the second part of the shoulder member.

7. An assembly for a turbomachine, comprising: a nozzle sector, and a sealing sector axially adjacent to the nozzle sector, wherein the nozzle sector includes vanes, a hooking member and a shoulder member, the hooking member having a projection radially extending towards an outside of the sector relative to the vanes, the hooking member being configured to be secured to a casing radially surrounding the nozzle sector, wherein a recess is provided through at least one part of a distal end of the projection, the recess accommodating the shoulder member, wherein the shoulder member is configured to form an anti-rotation stop for a surface of the sealing sector axially adjacent to the nozzle sector, wherein the shoulder member is configured to be mounted and secured in the recess before assembling the nozzle sector in the turbomachine, wherein the shoulder member forms an anti-rotation stop for a surface of the sealing sector, relative to the nozzle sector.

8. A turbine for a turbomachine, comprising: an assembly according to claim 7, a turbomachine casing and an anti-rotation slug secured to the casing, wherein the anti-rotation slug and the shoulder member are each at least partially accommodated in the recess, so that the anti-rotation slug forms an anti-rotation stop of the nozzle sector relative to the casing.

9. The turbine according to claim 8, wherein the shoulder member includes a recess at least partially accommodating the anti-rotation slug.

10. An aircraft turbo-machine including a turbine according to claim 8.

11. A method for manufacturing a nozzle sector of an aircraft turbomachine, wherein the nozzle sector includes vanes, a hooking member and a shoulder member, the hooking member having a projection radially extending towards an outside of the sector relative to the vanes, the hooking member being configured to be secured to a casing radially surrounding the nozzle sector, wherein a recess is provided through at least one part of a distal end of the projection, the recess accommodating the shoulder member, wherein the shoulder member is configured to form an anti-rotation stop for a surface of a sealing sector axially adjacent to the nozzle sector, wherein the shoulder member is configured to be mounted and secured in the recess before assembling the nozzle sector in the turbomachine, wherein the method includes the following steps: machining a surface of a projection of said sector, wherein the surface of the projection is configured to form an inner ridge with a contact surface of a shoulder member, machining a recess through at least one part of a distal end of the projection, manufacturing said shoulder member, assembling said shoulder member in the recess of the nozzle sector.

12. The manufacturing method according to claim 11, wherein machining the recess and/or machining the surface of the projection is performed by resurfacing, grinding, or milling.

13. The manufacturing method according to claim 11, including a step of securing the shoulder member in the recess by welding, crimping, or soldering.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood and further characteristics, details, and advantages thereof will appear more clearly upon reading the following description, made by way of non-limiting example and with reference to the appended drawings, in which:

(2) FIG. 1A is a cross-section view of a part of a low pressure turbine showing hooking means carried by an end of a prior art nozzle sector, and cooperating with a projection of an adjacent sealing sector;

(3) FIG. 1B is a perspective view of the turbine part of FIG. 1A;

(4) FIGS. 2 and 3 are perspective views from two different angles of alternative downstream hooking means comprised by the prior art low pressure nozzle sector;

(5) FIG. 4 is a perspective view of a first part of an improved hooking means for a low pressure nozzle sector;

(6) FIG. 5A is a perspective view of a wedge of an improved hooking means, which is inserted and complementary to the first part shown in FIG. 4;

(7) FIG. 5B is a vertical cross-section view of a middle part of the wedge of FIG. 5A; and,

(8) FIGS. 6 and 7 are perspective views from two different angles of the parts of the hooking means of FIGS. 4 and 5 in the assembled condition.

DETAILED DISCLOSURE OF PARTICULAR EMBODIMENTS

(9) FIG. 4 illustrates a nozzle 52 sector 56 which has a plurality of vanes 60.

(10) The sector 56 has downstream hooking means 64. These means 64 have two rims 68 and 70.

(11) The rim 68 extends angled, towards the outside of the turbine and downstream (that is upwards and towards the right side of FIG. 4).

(12) The rim 70 includes a radial portion 70a and an axial portion 70b.

(13) The radial portion 70a includes two upstream and downstream radial surfaces, respectively 78a (FIG. 7) and 78b (FIG. 4).

(14) The portion 70b extends as a cornice from the distal end of the portion 70a, transversely and downstream up to an end surface 78c. The portion 70b includes two outer and inner annular surfaces, respectively 80a and 80b. The radial thickness of the portion 70b between the surfaces 80a and 80b is here constant throughout the angular extent of the sector 56.

(15) A recess 72 is provided across the axial portion 70b (FIG. 4).

(16) The recess 72 axially extends from the surface 78a up to the end surface 78c, that is it longitudinally passes throughout the axial portion 70b. The recess 72 further radially extends from the surface 80a up to a bottom surface 86a, which is here planar, over a height greater than the radial thickness of the portion 70b. The recess 72 also has two opposite side surfaces 88a and 88b which are here parallel.

(17) A shoulder member, here the wedge 74, is provided to be mounted on the rim 70 (FIG. 6) thus forming an anti-rotation shoulder.

(18) The wedge 74 is here made in a single piece with a top part 74a and a bottom part 74b (respectively at the top and the bottom of FIG. 5A). The top part 74a has a width lower than the bottom part 74b.

(19) The top part 74a is provided to be mounted in the recess 72.

(20) The top part 74a has here a height equal to the thickness of the axial portion 70b. Thus, when the wedge 74 is mounted on the rim 70, an upper surface 80c of the top part 74a is coextensive with the outer surface 80a, whereas an upper surface 80d of the bottom part 74b is flat against the inner surface 80b. Moreover, a T-shaped planar surface 78d, shared by the top and bottom parts 74a and 74b, is coextensive with the end surface 78c of the axial portion 70b, whereas a surface 78e of the bottom part 74b is flat against the surface 78b of the radial portion 70a (FIG. 6).

(21) The bottom part 74b of the wedge 74 laterally extends between two end surfaces 82a and 82b (FIG. 5A). The surface 82a is intended to contact a corresponding surface of the anti-rotation projection 27 of the sealing sector 26 shown in FIGS. 1A and 1B. The surface 82a can have for example, but not exclusively, a radial or slight angle orientation relative to a radial orientation. Alternatively, the surface 82a may be replaced by another structure (not shown), such as a hooking means, a surface with a slug or other means allowing a reliable contact between the sector 56 and the sealing sector 26.

(22) The wedge 74 itself has a recess 84 provided in the bottom part 74b (FIGS. 5B and 7). This recess 84 is delimited by a curved bottom surface 86b, the latter being lined with two side surfaces 88c and 88d. The surfaces 88c and 88d are arranged to come into the plane of the surfaces 88a and 88b respectively.

(23) A planar surface 86c here extends from the bottom surface 86b, tangentially thereto and angled up to the upper surface 80c. The surface 86b is here provided to be tangentially coextensive with the bottom surface 86a of the recess 72.

(24) The recess 84 and the recess part 72 which is not obstructed by the wedge 74 form together a hollow having dimensions similar to the recess 32 shown in FIG. 2.

(25) The connection between the sector 56 and the wedge 74 does not have to be as robust as in the case of the shoulder 34 formed in a single piece with the sector 16. Indeed, the wedge 74 works in shear (and not in tension). Thus, the wedge 74 can be sealingly secured to the sector 56 by a connection of the crimping, soldering, or welding type or by any other method while ensuring the desired mechanism strength and the functions of the sector 16 described in the preamble.

(26) Advantageously, and unlike the surfaces of the recess 32 which are EDM machined, the surfaces of the recess 72, as well as the downstream surface 78b of the rim 70 and the inner surface 80b of the axial portion 70b, can be machined before placing the wedge 74, by an economical means such as resurfacing.

(27) It is also possible to form the outer surfaces of the wedge 74 by resurfacing, especially the surface 82a.

(28) Manufacturing the sector 56 can thus include the following steps: machining the surfaces 78b and 80b of the rim 70 by resurfacing, grinding, or milling, machining the recess 72 by resurfacing, grinding, or milling, manufacturing the wedge 74 independently of the sector 56, and assembling the wedge 74 with the sector 56.

(29) This method enables a better radius of curvature to be obtained at the junction between the surface 82a and both transverse surfaces 78b and 80b than in the method described in the preamble. In other words, the surface 82a is separately machined with a good flatness. The surface 82a is at the tip of the piece, that is connected to the adjacent surfaces of the wedge 74 by outer ridges, which are simpler to machine than inner ridges.

(30) Mounting a wedge such as 74 on such a sector 56 of a low pressure nozzle enables the machining to be simplified, the costs thereof to be reduced, the radius of curvature between the contact surface 82a and the transverse surfaces to be improved, and the adjustment cost and time of the electrodes imposed by EDM to be avoided without a performance loss.

(31) Advantageously, the casing 14 forms a rotationally blocking member of the sector 56, directly or through a non-represented slug, for example by contact on the surface 88a and/or the surface 88b, whereas the sector 56 forms a rotationally blocking member of the axially adjacent sector 26 through the wedge 74.

(32) Thus, the reference rotationally blocking member of the sector 56 is different from the reference rotationally blocking member of the sector 26. This enables the sectors to be easily and rapidly mounted in the turbomachine.

(33) Of course, without departing from the scope of the invention, modifications can be brought to the implementation form given as an example.