Assembly for a turbine engine

Abstract

An assembly (50) for a turbine engine includes an annular row of stator blades with a longitudinal axis (B) having variable pitch blades each comprising a radial vane (6), at least one of its ends of which is connected to a radially extending pivot (14) and being engaged in rotation around its axis (A) in a ring (16), characterised in that a tubular component (26) is mounted coaxially around the pivot (14), wherein said tubular component (26) comprises a first annular zone (26a) mounted tightly on the pivot (14) and a second annular zone (26b) comprising an annular bulge (28) extending substantially radially outwards in relation to the axis (A) of the pivot (14), wherein the annular bulge (28) and the pivot (14) define an annular space (30).

Claims

1. Assembly (50) for a turbine engine comprising an annular row of stator blades (2) with a longitudinal axis (B) having variable pitch blades (4) each comprising a radial vane (6), at least one of its ends of which is connected to a radially extending pivot (8, 14) and being engaged in rotation around its axis (A) in a ring (16), characterised in that a tubular component (26) is mounted coaxially around the pivot (8,14), wherein said tubular component (26) comprises a first annular zone (26a) mounted tightly on the pivot (8,14) and a second annular zone (26b) comprising an annular bulge (28) extending substantially radially outwards in relation to the axis (A) of the pivot (8,14), wherein the annular bulge (28) and the pivot (8,14) define an annular space (30).

2. Assembly (50) according to claim 1, characterised in that said tubular component (26) is mounted on the pivot (8,14) of the blade (4) such that the first annular zone (26a) is interposed along the axis (A) of said pivot (8,14) between the annular bulge (28) and a support plate (20) of the vane (6).

3. Assembly (50) according to claim 1, characterised in that a third annular zone (26c) is formed on the tubular component (26) along the axis (A) of said pivot (8,14) such that the second annular zone (26b) is interposed between the first annular zone (26a) and the third annular zone (26c); wherein the third annular zone (26c) comprises an annular face (32) radially internal in relation to the axis (A) of the pivot (8,14) in contact with said pivot (8,14).

4. Assembly (50) according to claim 3, characterised in that said annular face (32) is convex rounded shape.

5. Assembly (50) according to claim 1, characterised in that the annular bulge (28) comprises a face that is radially internal (28a) in relation to the axis (A) of the pivot (8,14) which is concave and a face that is radially external (28b) in relation to the axis (A) of the pivot (8,14) which is convex.

6. Assembly (50) according to claim 1, characterised in that the first zone (26a) is formed at a first end (34) of the tubular component (26).

7. Assembly (50) according to claim 3, characterised in that the third annular zone (26c) is formed at a second end (36) of the tubular component (26).

8. Assembly (50) according to claim 1, characterised in that said pivot (14) is formed at the end of the blade (4) that is radially internal in relation to the longitudinal axis (B).

9. Assembly (50) according to claim 1, characterised in that the ring (16) comprises a plurality of housings (18), regularly distributed around the axis of the ring.

10. Assembly (50) according to claim 9, characterised in that said tubular component is mounted coaxially around a pivot (8,14) and is accommodated in one of the housings (18), such that the radially external face (28b) of the annular bulge (28) is stressed radially towards the inside of the housing.

11. Assembly (50) according to claim 10, characterised in that said plurality of housings (18) each respectively receives a bush (38) in which a tubular component (26) surrounding a pivot (14) is engaged.

12. Turbine engine comprising at least one assembly according to a compressor according to claim 10.

13. Assembly (50) according to claim 9, characterised in that said plurality of housings (18) each respectively receives a bush (38) in which a tubular component (26) surrounding a pivot (14) is engaged.

14. Turbine engine compressor characterised in that it comprises at least one assembly according to claim 1.

15. Turbine engine comprising at least one assembly according to claim 1.

16. A high-pressure compressor characterised in that it comprises at least one assembly according to claim 1.

17. A turbojet or a turboprop comprising at least one assembly according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a diagrammatic perspective partial view of an annular row of blades of the stators;

(2) FIG. 2 is a diagrammatic perspective view of a variable pitch stator blade, isolated and mounted on a ring;

(3) FIG. 3 is a longitudinal cross-sectional view of an assembly comprising the internal pivot of a variable pitch stator blade according to the prior art, mounted on the ring;

(4) FIG. 4 is a longitudinal cross-sectional view of an assembly comprising the internal pivot of a variable pitch stator blade according to the invention, before mounting on the ring;

(5) FIG. 5 is a diagrammatic longitudinal cross-sectional view of the assembly in FIG. 4 mounted on the ring.

DETAILED DESCRIPTION

(6) Reference is now made to FIG. 4 and following figures in connection with the invention, FIGS. 1 to 3 having already been described above and relating to the known technique.

(7) FIG. 4 illustrates an assembly 50 comprising the internal pivot 14 of a variable pitch stator blade 4 according to the invention, before mounting on the ring 16. As in the prior art, the assembly 50 furthermore comprises a tubular component 26.

(8) The tubular component 26 according to the invention differs from that of the prior art by its geometry. Indeed, the tubular component 26 according to the invention comprises a first annular zone 26a mounted tightly, i.e. shrink-fitted, around the pivot 14. The tubular component 26 according to the invention furthermore comprises a second annular zone 26b. The second annular zone comprises an annular bulge 28 extending radially outwards in relation to the axis A of the pivot and defining in conjunction with the pivot 14 an annular space 30.

(9) Thus, as can be seen in FIG. 4, the tubular component comprises, along the axis A of the pivot, a first annular zone 26a mounted tightly on the pivot 14, followed by a second annular zone 26b comprising an annular bulge 28.

(10) The annular bulge 28 of the second zone is defined by a face that is radially internal 28a in relation to the pivot axis which is concave and a face that is radially external 28b in relation to the pivot axis which is convex. A bulge 28 of this kind can be obtained for example by deformation of a cylindrical tubular component, thus forming a convex annular zone. The tubular component 26 may furthermore exhibit a constant thickness from its first to its second end. The thickness is on the order of 1.5 mm for example, depending on the constituent material of the tubular component.

(11) Such a geometry of the tubular component 26, which in the prior art was mounted tightly on the pivot along the former's entire length, makes it possible, during operation, to guarantee the flexibility and damping of the link between the pivot 14 and the ring 16. Such flexibility relieves the static stresses exerted on the link. Such damping furthermore relieves the vibratory stresses exerted on the link.

(12) With such as geometry, the tubular component 26, as a wearing part, makes it possible to improve the service life of the variable pitch stator blades 4, and in particular that of the internal pivots 14. It thus reduces some of the stresses exerted in the connection area between the pivot 14 and the vane 6 of the variable pitch stator blades 4.

(13) In addition, the geometry of the tubular component 26 allows better control of the areas in which the stresses experienced by the tubular component 26 are concentrated, and thus distribution of the stresses experienced by the tubular component 26 over a surface instead of at contact points, in order to slow the wear of this tubular component 26.

(14) As illustrated in FIG. 4, the tubular component 26 is mounted on the blade pivot 14 such that the first annular zone 26a is interposed along the axis A of said pivot between the annular bulge 28 and a support plate 20 of the vane 6. By positioning the tubular component 26 around the pivot 14, the risk of translation of the tubular component 26 towards the plate 20, which may damage the plate 20 is reduced.

(15) A third annular zone 26c, visible in FIG. 4, is formed on the tubular component 26. The third annular zone 26c is arranged such that the second annular zone 26b is interposed between the first annular zone 26a and the third annular zone 26c.

(16) The third annular zone 26c is delimited internally by an annular face 32 that is radially internal in relation to the axis A of the pivot 14. The annular face 32 that is radially internal in relation to the axis A of the pivot 14 of the third zone 26c defines with the pivot 14 an annular clearance depending on the torques of the materials used for the design of the tubular component 28 and the operating conditions of said turbine engine, so as to ensure adequate sliding.

(17) FIG. 4 represents an intermediate assembly position in which the presence of an annular clearance j is visible. Owing to the clearance j between the third annular zone 26c and the pivot 14, the tubular component 26 can relax or tighten radially as a function of the stresses to which it is exposed, applied by the pivot 14. When the assembly is mounted on the ring 16, this annular clearance j between the third annular zone 26c and the pivot 14 is abolished (FIG. 5).

(18) The annular face 32 that is radially internal in relation to the pivot of the third zone 26c may be convex rounded shape. The convex rounded shape of the annular face 32 makes it possible in particular to avoid the latter's rubbing against the pivot 14 during its translational movements and furthermore ensures improved sliding of the pivot 14.

(19) The first annular zone 26a may, in a particular embodiment, be formed at a first end 34 of the tubular component 26, particularly the first end 34 that may be radially external.

(20) In another embodiment of the invention, the third zone 26c may be formed at a second end 36 of the tubular component 26, particularly the second end 36 that may be radially internal.

(21) The length of the tubular component 26 is for example such that it covers between 70% and 90% of the pivot.

(22) The first, 26a, second 26b and third 26c annular zones of the tubular component 26 respectively represent approximately 25%, 60% and 15% of the total length of the tubular component.

(23) Mounting of the assembly 50 in FIG. 4 on the ring 16 is illustrated in FIG. 5. As illustrated, once the assembly is mounted on the ring 16, the annular clearance j between the third annular zone 26c and the pivot 14 is abolished. The housings 18 in the ring each receive a bush 38 in which the tubular component 26 surrounding a pivot 14 is engaged. The bush 38, a wearing part improving the service life of the pivot 14 and the tubular component 26 during operation, is integral with the housing 18.

(24) As can be seen in FIG. 5, the housing 18 is delimited by an annular wall of axis A. In practice, it is noticed that the radially external face 28b of the annular bulge 28 abuts radially outwards against an internal annular face of the bush 38, as a result of prestressed installation of the annular bulge 28 in the bush 38. The bush 38 is fixedly installed inside the housing 18, i.e. inside the annular wall delimiting the housing 18. Angular setting of a blade 4 around its axis A is carried out by rotating the pivot 14, with the tubular component 26 integral with the pivot 14 moving in rotation around the axis A in relation to the bush 38.