Assembly for a turbine engine

Abstract

The invention relates to an assembly for a turbine engine, comprising: - an outer turbine casing (20) which comprises an annular wall (21) extending around an axis (X1), the outer casing (20) comprising an upstream hook (22a) and a downstream hook (22b) which project radially towards the inside of the annular wall (21); - a sealing ring (30) arranged radially inside the annular wall (21) of the outer casing (20), the sealing ring (30) being mounted on the outer casing (20) via an upstream hooking means (33a) and a downstream hooking means (33b), engaging with the upstream hook (22a) and the downstream hook (22b), respectively; - abutment means rigidly connected to the outer casing (20) and configured to prevent a downstream (AV) axial translation movement of the sealing ring (30) with respect to the outer casing (20).

Description

Description Title: Turbomachine Assembly technical field

[0001] This description relates to a turbomachine assembly comprising in particular an external casing and a downstream turbine stage rotor part. Previous technique

[0002] A turbomachine 10, as shown in Figure 1, typically has an axis X1 which corresponds to the axis of rotation of the rotating parts. The turbomachine 10 comprises, from upstream to downstream in the direction of gas flow, a fan 11, at least one compressor 12, a combustion chamber 14, and at least one turbine 16. The air from the fan 11 is divided into a primary flow in a primary annular stream and a secondary flow in a secondary annular stream surrounding the primary annular stream. The compressor 12, the combustion chamber 14, and the turbine 16 are located within the primary stream.

[0003] Typically, the turbine 16 comprises one or more stages, each stage consisting, from upstream to downstream, of an annular row of stator blades and an annular row of rotor blades. The annular row of rotor blades in each stage of the turbine 16 is rotationally coupled to a rotor of the compressor 12 via a shaft 18. The blower 11 can be connected directly to the rotor of the compressor 12 or, for example, via an epicyclic gear train.

[0004] Each stage comprises a ring surrounding the annular array of rotor blades and externally defining the gas flow path. The ring of each stage includes an annular platform, the radially inner surface of which may have an abradable coating designed to limit airflow between the radially outer end of the blades and the ring. The ring also provides a thermal barrier.

[0005] This disclosure proposes an arrangement that facilitates the attachment of the ring to the outer casing, particularly for the downstream stage of the turbine. Summary

[0006] A turbomachine assembly is offered, comprising: - an external casing comprising an annular wall extending around an axis, the external casing comprising an upstream hook and a downstream hook extending radially inward towards the interior of the annular wall, - a sealing ring arranged radially inside the annular wall of the outer casing, the sealing ring supporting an abradable element intended to face radially an annular row of rotor blades, the sealing ring being mounted on the outer casing by means of an upstream attachment means and a downstream attachment means, each having a U-shaped attachment portion engaged respectively with the upstream hook and the downstream hook, - stop means attached to the outer casing and configured to prevent axial translation movement downstream of the sealing ring relative to the outer casing.

[0007] The upstream hook and the downstream hook may each comprise a first wall extending radially inwards from the annular wall and a second wall extending axially downstream from the first wall, the hooking portion of the upstream hooking means and the hooking portion of the downstream hooking means having a U-shape, each comprising a radially external branch and a radially internal branch extending axially upstream from a median branch.

[0008] The radially external branch of the hooking portion of the upstream hooking means can be radially supported inwards on the second wall of the upstream hook and the radially external branch of the hooking portion of the downstream hooking means can be radially supported inwards on the second wall of the downstream hook.

[0009] The radially internal branch of the hooking portion of the upstream hooking means may be radially supported outwards on the second wall of the upstream hook and / or the radially internal branch of the hooking portion of the downstream hooking means may be radially supported outwards on the second wall of the downstream hook.

[0010] A radial play can be formed radially between the radially internal branch of the hooking portion of the upstream hooking means and the second wall of the upstream hook.

[0011] The middle branch of the upstream hooking portion may be axially supported upstream on the second wall of the upstream hook and / or the middle branch of the downstream hooking portion may be axially supported upstream on the second wall of the downstream hook.

[0012] The sealing ring may comprise an annular platform having a radially internal face and a radially external face, the abradable element being carried on the radially internal face of the annular platform. The upstream and downstream attachment means may each comprise an L-shaped connecting portion fixed to the radially external face of the annular platform of the sealing ring.

[0013] The stop means can be formed by at least one tool fixed to the external casing, the tool being arranged downstream of the sealing ring and comprising a first bearing face bearing axially upstream on the sealing ring.

[0014] The first bearing face of the tooling can bear on the hooking portion of the downstream hooking means.

[0015] The first bearing face of said at least one tool may bear axially upstream on the middle branch of the attachment portion of the downstream attachment means of the sealing ring.

[0016] The first bearing face of said at least one tool may bear axially on a downstream edge of the annular platform.

[0017] The external casing may include a downstream flange, preferably radial.

[0018] The said tooling may include a second bearing face axially upstream on a downstream face of the downstream flange of the external housing, the second bearing face preferably being arranged radially outside with respect to the first bearing face.

[0019] The downstream flange of the external housing may comprise one or more scallops distributed, preferably regularly, around the axis, each scallop comprising a through hole in the axial direction, and in which said at least one tool comprises one or more threaded rods extending from the second bearing face of the radially external part, through the hole of an associated scallop among said one or more scallops of the downstream flange of the external housing, said at least one tool further comprising a nut associated with each threaded rod, each nut being screwed onto the threaded rod to bear against and tightened axially on an upstream face of the downstream flange of the external housing.

[0020] The assembly may include an exhaust housing arranged downstream of the outer housing. The stop means may be formed by a radial wall of the exhaust housing arranged opposite, or bearing axially against, the sealing ring, preferably the attachment portion of the downstream attachment means.

[0021] The exhaust housing can be attached to the outer housing, preferably by bolting.

[0022] The assembly includes a gasket in the form of a corrugated plate, preferably annular, the gasket being axially interposed between the downstream attachment means of the sealing ring and the radial wall of the exhaust housing. Brief description of the drawings

[0023] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which:

[0024] Figure 1 is a schematic cross-sectional view representing a turbomachine according to the prior art.

[0025] Figure 2 is a schematic cross-sectional view that represents an external turbine casing and a final stage turbine rotor portion as described herein.

[0026] Figure 3 is a schematic cross-sectional view that represents a displacement of an abradable element support ring of the last stage rotor part of a turbine relative to the external casing that may occur during transport.

[0027] Figure 4 is a schematic perspective view which represents a first variant of a tooling according to the present description for holding the ring of the rotor part of the last turbine stage to the external casing during transport.

[0028] Figure 5 is a schematic perspective view that represents the tooling of figure 4 attached to the external casing.

[0029] Figure 6 is a schematic cross-sectional view that represents the rotor part of the last stage of a turbomachine turbine in which the ring is held to the outer casing by means of the tooling of Figure 4.

[0030] Figure 7 is a schematic perspective view which represents a second variant of a tooling according to the present description for retaining the ring of the rotor part of the last turbine stage to the external casing during transport.

[0031] Figure 8 is a schematic perspective view that represents the tooling of figure 7 attached to the external housing.

[0032] Figure 9 is a schematic perspective view which represents the ring of the rotor part of the last turbine stage, held to the external casing by means of the tooling of Figure 7.

[0033] Figure 10 is a schematic cross-sectional view that represents an external turbine casing, a final stage turbine rotor portion and a turbomachine exhaust casing. Description of the implementation methods

[0034] An assembly for a turbomachine is now described with reference to Figure 2.

[0035] The assembly includes first of all an external turbine casing 20 which includes an annular wall 21 extending axially along an axis X1.

[0036] In this exposition, the axial direction X corresponds to the direction of the X1 axis. Orientation qualifiers such as "axial," "radial," or "circumferential" are defined, unless otherwise specified, with reference to the X1 axis. A radial direction is a direction perpendicular to the direction of the X1 axis. A circumferential direction, at a point far from the X1 axis, corresponds to a direction perpendicular to both the axial X and radial directions. Furthermore, unless otherwise specified, the adjectives "inside," "internal," "outside," and "external" are used with reference to a radial direction, such that the internal (radially internal) part of an element is closer to the X1 axis than the external (radially external) part of the same element.Finally, the relative terms "upstream" and "downstream" are defined in relation to the normal direction of fluid flow, from upstream to downstream (AV), in a turbomachine. Therefore, the X1 axis can coincide with an X1 axis of rotation of the rotor parts of a turbomachine in which the assembly is suitable for mounting.

[0037] The term "annular" used in this description refers to parts extending circumferentially, such parts being able to be made in the form of a ring, preferably continuous, or in the form of ring sectors arranged to be circumferentially end to end.

[0038] The annular wall 21 of the external housing 20 may be, in whole or in part, cylindrical or frustoconical about the axis X1. The annular wall 21 may include an internal face.

[0039] The outer casing 20 includes one or more hooks 22a; 22b projecting radially inwards from the annular wall 21. Each hook 22a; 22b may project radially towards the interior from the inner face of the annular wall 21. Each hook 22a; 22b may comprise a first wall 23 extending radially inward from the annular wall 21 and a second wall 24 extending axially. The second wall 24 may extend axially downstream AV from the first wall 23, in particular from a radially internal end portion of the first wall 23. The second wall 24 may be cylindrical or frustoconical about the axis X1. Each hook 22a; 22b may be annular about the axis X1.

[0040] Said one or more hooks 22a; 22b may include an upstream hook 22a and a downstream hook 22b, spaced apart from each other along the axial direction X.

[0041] The external housing 20 may include a downstream flange 25, preferably annular. The downstream flange 25 may extend radially outwards from the annular wall 21, in particular from a downstream end portion of the annular wall 21. The downstream flange 25 may include a downstream face and an upstream face, axially opposed to each other.

[0042] The downstream flange 25 may include one or more scallops 26 distributed, preferably regularly, around the axis X1. Each scallop 26 may project radially outwards from the annular wall 21 of the outer housing 20. Each scallop 26 may include a hole 27 passing through it along the axial direction X. The hole 27 through each scallop 26 may be adapted to accommodate a bolted connecting screw. The reader may refer to Figures 5, 8, and 9, in which this aspect of the downstream flange 25 is more clearly visible.

[0043] The assembly also includes a sealing ring 30 which is arranged radially inside the annular wall 21 of the outer casing 20. The inner face of the annular wall 21 of the outer casing 20 can be radially opposite the sealing ring 30. The sealing ring 30 supports an abradable material 32 intended to be radially opposite an annular row of rotor blades 40.

[0044] The sealing ring 30 may include an annular platform 31. The annular platform 31 may include a radially internal face. The radially internal face may be adapted to support the abradable material 32. The annular platform 31 may further include a radially external face.

[0045] The sealing ring 30 may include the abradable material 32. The abradable material 32 may be carried by the annular platform 31, in particular by the radially internal face of the annular platform 31. The abradable material 32 may be suitable for sealing with the rotor blades 40. A radially internal face of the abradable material 32 may radially delimit an annular primary gas flow channel on the outside when the sealing ring 30 is mounted in a turbomachine.

[0046] The sealing ring 30 is radially supported by the outer casing 20. The sealing ring 30 comprises one or more attachment means 33a; 33b, each cooperating with an associated hook among said one or more hooks 22a; 22b of the outer casing 20, so as to ensure radial and axial retention upstream AM of the sealing ring 30 relative to the outer casing 20. In other words, the engagement of said one or more attachment means 33a; 33b each with an associated hook among said one or more hooks 22a; 22b ensures a blocking in axial translation upstream AM and radial translation inward of the sealing ring 30 relative to the external casing 20.

[0047] The said one or more hooking means 33a; 33b may include an upstream hooking means 33a and a downstream hooking means 33b, separated from each other along the axial direction X. The upstream hooking means 33a may cooperate with the upstream hook 22a and the downstream hooking means 33b may cooperate with the downstream hook 22b.

[0048] The upstream attachment means 33a and a downstream attachment means 33b each have a U-shaped attachment portion 34 engaged respectively with the upstream hook 22a and the downstream hook 22b. This facilitates and secures the attachment of the sealing ring 30 to the outer casing 20. The U-shaped attachment portions 34 of the upstream attachment means 33a and the attachment portion 34 of the downstream attachment means 33b can each comprise a radially external arm 34a and a radially internal arm 34b extending axially upstream AM from a central arm 34c. The central arm 34c of the attachment portion 34 of each attachment means 33a, 33b can extend radially.

[0049] The radially external branch 34a of the hooking portion 34 of the upstream hooking means 33a can be radially supported inwards on the second wall 24 of the upstream hook 22a and the radially external branch 34a of the hooking portion 34 of the downstream hooking means 33b can be radially supported inwards on the second wall 24 of the downstream hook 22b. This allows radial support of the sealing ring 30 relative to the external housing 20. Optionally or additionally, the radially internal branch 34b of the hooking portion 34 of the upstream hooking means 33a can be radially supported outwards on the second wall 24 of the upstream hook 22a or, as shown in Figure 2, a radial clearance can be formed radially between the radially internal branch 34b of the hooking portion 34 of the upstream hooking means 33a and the second wall 24 of the upstream hook 22a.Optionally or even more, the radially internal branch 34b of the hooking portion 34 of the downstream hooking means 33b can be radially supported outwards on the second wall 24 of the downstream hook 22b, which further improves the radial retention between the outer casing 20 and the sealing ring 30.

[0050] The middle arm 34c of the attachment portion 34 of the upstream attachment means 33a can bear axially upstream AM on the second wall 24 of the upstream hook 22a and / or the middle arm 34c of the attachment portion 34 of the downstream attachment means 33b can bear axially upstream AM on the second wall 24 of the downstream hook 22b. This prevents axial displacement upstream AM of the sealing ring 30 relative to the external housing 20.

[0051] Each attachment means 33a; 33b can be fixed to the annular platform 31, in particular to the radially external face of the annular platform 31. The upstream attachment means 33a and the downstream attachment means 33b can each comprise an L-shaped connecting portion 35 fixedly connected to the radially external face of the annular platform 31. The sealing ring 30, preferably by brazing. The connecting portion 35 of each attachment means 33a; 33b may comprise an axial branch 35a and a radial branch 35b. The upstream attachment means 33a and the downstream attachment means 33b may each be rigidly connected to the radially external face of the annular platform 31 at the axial branch 35a of their connecting portion 35. The axial branch 35a of the connecting portion 35 of the upstream attachment means 33a may extend axially from a radially internal end of the corresponding radial branch 35b, preferably downstream AV. The axial branch 35a of the connecting portion 35 of the downstream attachment means 33b may extend axially from a radially internal end of the corresponding radial branch 35b, preferably upstream AM.

[0052] At least one of said one or more fastening means 33a; 33b, or even each of said fastening means 33a; 33b, may be a single unit. Alternatively, or in addition, at least one of said one or more fastening means 33a; 33b, or even each of said fastening means 33a; 33b, may comprise several attached and interlocking parts. More specifically, the radial arm 35b of the connecting portion 35 of the upstream fastening means 33a may be formed from a material or permanently connected, preferably by brazing, to the central arm 34c of the fastening portion 34 of the upstream fastening means 33a. Similarly, the radial branch 35b of the connecting portion 35 of the downstream attachment means 33b can be made of material or connected solidly, preferably by brazing, to the radially internal branch 34b of the attachment portion 34 of the upstream attachment means 33a.

[0053] At least one of said one or more attachment means 33a; 33b, or even each of said attachment means 33a; 33b, may extend wholly or partially annularly around the axis X1 in a continuous manner. Alternatively, at least one of said one or more attachment means 33a; 33b, or even each of said attachment means 33a; 33b, may extend annularly around the axis X1 in a discontinuous manner. In other words, at least one of said one or more attachment means 33a; 33b, or even each of said attachment means 33a; 33b, may be formed by a plurality of elements distributed, preferably regularly, around the axis X1.

[0054] To facilitate its manufacture, the sealing ring 30 may comprise a plurality of sectors arranged circumferentially end to end. Each sector of the sealing ring 30 may also comprise an annular platform sector 31. Each sector of the sealing ring 30 may further comprise a sector of at least one of said one or more annular attachment means 33a; 33b around the axis X1.

[0055] The annular platform sectors 31 extend circumferentially between a first end and a second end. Each annular platform sector 31 comprises a first lateral face and a second lateral face at the first and second ends, respectively. The annular platform sectors 31 are arranged circumferentially end to end such that the first lateral face of one of the annular platform sectors 31 is circumferentially aligned with the second lateral face of another directly adjacent annular platform sector 31. Furthermore, the first lateral face and the The second lateral face of each annular platform sector 31 each comprises a circumferential slot 37. The sealing ring 30 may comprise a plurality of sealing fins. Each sealing fin may be received jointly in the slot 37 of the first lateral face of one of the annular platform sectors 31 and in the slot 37 of the second lateral face of another annular platform sector 31 which is circumferentially opposite.

[0056] Optionally, the assembly may further include an annular row of turbine rotor blades 40. The sealing ring 30 may surround the annular row of rotor blades 40. A radially external end of each rotor blade 40 may be radially opposite the abradable material 32. More specifically, the radially external end of each rotor blade 40 may cooperate in sealing with the abradable material 32. Each rotor blade 40 may include a radially extending blade and one or more blades projecting radially outward from the blade. A free end of said one or more blades of each rotor blade 40 may form the radially external end of the rotor blade 40.

[0057] The sealing ring 30 and the annular row of rotor blades 40 can form a rotor section of a turbomachine turbine stage, preferably a downstream turbine stage. "Downstream stage" is understood to mean the stage furthest downstream of the turbine. The rotor section of a turbomachine stage differs from a stator section comprising a row of stator blades as described with reference to the prior art. Thus, generally, the assembly as described above can include the outer casing 20 and a rotor section of a downstream turbine stage.

[0058] Remarkably, the assembly includes stop means attached to the outer casing 20 and configured to prevent axial translational movement of the sealing ring 30 relative to the outer casing 20 downstream AV.

[0059] According to a first aspect, the stop means may include at least one tool 100 fixed securely to the outer casing 20, downstream of the sealing ring 30. The tool 100 further includes at least one first bearing face 102 bearing axially on the sealing ring 30 to ensure axial retention towards the downstream AV of the sealing ring 30 relative to the outer casing 20.

[0060] The assembly is thus configured to allow for transport without separation between the outer casing 20 and the sealing ring 30, which would be due to axial movement downstream (AV) of the sealing ring 30. Indeed, the outer casing 20 and the sealing ring 30 are likely to be assembled at a first manufacturing site and then moved to a second manufacturing site for integration into a turbomachine. However, as shown in Figure 3, without the tooling 100 to ensure axial support downstream of the sealing ring 30, the movements occurring during transport could cause a disengagement between the ring's attachment means 33a; 33b and the hooks 22a; 22b of the outer casing 20. This would then necessitate time-consuming and costly operations to reassemble the sealing ring 30 and the outer casing 20 upon receipt. Furthermore, in the worst-case scenario, the sealing ring 30 and the External casing 20 can collide during transit and be damaged, which then requires their partial or total replacement.

[0061] Thus, the use of tooling 100 reduces, or even eliminates, the risk of damage during transport and the risks associated with additional reassembly operations after transport. It is understood that tooling 100 is intended to be removed for the integration of the outer casing 20 and the sealing ring 30 into a turbomachine, particularly for assembly with an exhaust casing 50 as described later. Tooling 100 is therefore not intended to be retained during the assembly of the ring and the outer casing 20 into a turbomachine.

[0062] Each tool 100 can include a radially internal part 101 which includes the first bearing face 102 which is axially supported on the sealing ring 30 to ensure axial retention towards the downstream AV of the sealing ring 30 relative to the external housing 20.

[0063] The first bearing face 102 of the tooling 100 can bear upstream AM on the sealing ring 30.

[0064] According to a first alternative shown in Figures 4 to 6, the first bearing face 102 of the tooling 100 can bear on one or more of said attachment means 33a; 33b of the sealing ring 30, in this case on the downstream attachment means 33b. More particularly, the first bearing face 102 of the tooling 100 can bear axially upstream AM on the middle arm 34c of the attachment portion 34 of the downstream attachment means 33b.

[0065] According to a second alternative shown in figures 7 to 9, the first bearing face 102 of the tooling 100 can bear axially upstream AM on the annular platform 31 and / or on the abradable material 32 of the sealing ring 30, in particular on a downstream edge of the annular platform 31 and / or a downstream edge of the abradable material 32.

[0066] The first alternative and the second alternative are not mutually exclusive. An embodiment in which the first bearing face 102 comprises a first part bearing axially upstream AM on the downstream attachment means 33b of the sealing ring 30 and a second part bearing axially upstream AM on the annular platform 31 and / or on the abradable material 32 of the sealing ring 30 is not excluded.

[0067] Each tool 100 may include a second bearing face 104 bearing axially on the downstream flange 25, in particular on the downstream face of the downstream flange 25 of the outer housing 20. The second bearing face 104 may be arranged radially outwards relative to the first bearing face 102. Each tool 100 may include a radially external portion 103 adapted to secure the tool 100 to the outer housing 20. The radially external portion 103 of each tool 100 may include the second bearing face 104. In the first alternative, the first bearing face 102 may be offset upstream AM relative to the second bearing face 104. In the second alternative, the first bearing face 102 may be offset downstream AV relative to the second bearing face 104.

[0068] The first support face 102 and / or the second support face of each tool 100 can each be oriented upstream AM.

[0069] The radially internal part 101 and the radially external part 103 of the sealing ring 30 can be made from material or be added and fixed to each other.

[0070] Each tool 100 may include one or more threaded rods 110 extending upstream AM from the second bearing face 104 of the radially external part 103. Each threaded rod 110 may extend through the hole 27 of a scallop 26 associated with one or more scallops 26 of the downstream flange 25 of the external housing 20. The tool 100 may further include a nut 111 associated with each threaded rod 110, each nut 111 being screwed onto the threaded rod 110 to bear against and tighten axially against the upstream face of the downstream flange 25 of the external housing 20.

[0071] Preferably, as seen in figures 7 to 9, each tool 100 includes at least two threaded rods 1 10 as described above, in order to lock the tool 100 in rotation around an axis X1 parallel to the axis X1.

[0072] Each tool 100 can extend circumferentially between a first end and a second end. Each tool 100 can extend circumferentially around the axis X1 over an angular sector less than 45°, preferably less than 20°, preferably even less than 10°, and preferably even less than 5°. In other words, generally, said at least one tool 100 may not be annular. Each tool 100 can extend circumferentially over an angular sector less than the angular sector over which the sealing ring sectors 30 extend. In other words, the circumferential dimension of each tool 100 may be less than a circumferential dimension of the sealing ring sectors 30.

[0073] The set can include a plurality of 100 tools distributed, preferably regularly, around the X1 axis.

[0074] Contrary to the second aspect described below, the assembly may be without an exhaust casing 50 to which the external casing 20 is intended to be fixed, in particular via the downstream flange 25.

[0075] According to a second aspect, represented in figure 10, the assembly may include an exhaust housing 50 arranged radially downstream of the outer housing 20 and the sealing ring 30. The exhaust housing 50 may include an upstream flange 52, preferably annular, which is axially opposite, or even bearing against, the downstream flange 25 of the outer housing 20. The downstream flange 25 of the outer housing 20 and the upstream flange 52 of the exhaust housing 50 may be fixed to each other by bolting.

[0076] The exhaust housing 50 may include a radial wall 53 arranged axially opposite, or bearing against, the sealing ring 30, preferably at the attachment portion 34 of the downstream attachment means 33b. The stop means may include the radial wall 53 of the exhaust housing 50.

[0077] The exhaust housing 50 may include a frustoconical wall 51, preferably flaring outwards towards the upstream end AM. The downstream flange 25 may extend radially outwards from an upstream end portion of the frustoconical wall 51. The radial wall 53 may extend radially inwards from the upstream end portion of the frustoconical wall 51.

[0078] The assembly may also include a seal 54 having the shape of a corrugated plate, which for example has a general shape in omega cross-section, and preferably annular, interposed axially between the downstream attachment means 33b of the sealing ring 30 and the radial wall 53 of the exhaust housing 50.

Claims

Demands

1. Assembly for turbomachine, comprising: - an external casing (20) which includes an annular wall (21) extending around an axis (X1), the external casing (20) including an upstream hook (22a) and a downstream hook (22b) which extend radially inward towards the interior of the annular wall (21), - a sealing ring (30) arranged radially inside the annular wall (21) of the outer casing (20), the sealing ring (30) supporting an abradable element intended to face radially an annular row of rotor blades (40), the sealing ring (30) being mounted on the outer casing (20) by means of an upstream attachment means (33a) and a downstream attachment means (33b) which each have a U-shaped attachment portion (34) engaged respectively with the upstream hook (22a) and the downstream hook (22b), - stop means attached to the outer casing (20) and configured to prevent an axial translation movement downstream (AV) of the sealing ring (30) relative to the outer casing (20).

2. Assembly according to the preceding claim, wherein the upstream hook (22a) and the downstream hook (22b) each comprise a first wall (23) extending radially inwards from the annular wall (21) and a second wall (24) extending axially downstream (AV) from the first wall (23), the hooking portion (34) of the upstream hooking means (33a) and the hooking portion (34) of the downstream hooking means (33b) having a U-shape, each comprising a radially external branch (34a) and a radially internal branch (34b) extending axially upstream (AM) from a median branch (34c),and wherein the radially external branch (34a) of the hooking portion (34) of the upstream hooking means (33a) is radially supported inwards on the second wall (24) of the upstream hook (22a) and the radially external branch (34a) of the hooking portion (34) of the downstream hooking means (33b) is radially supported inwards on the second wall (24) of the downstream hook (22b).

3. Assembly according to the preceding claim, wherein the radially internal branch (34b) of the hooking portion (34) of the upstream hooking means (33a) is radially supported outwards on the second wall (24) of the upstream hook (22a) and / or the radially internal branch (34b) of the hooking portion (34) of the downstream hooking means (33b) is radially supported outwards on the second wall (24) of the downstream hook (22b).

4. Assembly according to claim 2, wherein a radial clearance is formed radially between the radially internal branch (34b) of the hooking portion (34) of the upstream hooking means (33a) and the second wall (24) of the upstream hook (22a).

5. Assembly according to the preceding claim, wherein the middle arm (34c) of the hooking portion (34) of the upstream hooking means (33a) is axially supported upstream (AM) on the second wall (24) of the upstream hook (22a) and / or the middle arm (34c) of the hooking portion (34) of the downstream hooking means (33b) is axially supported upstream (AM) on the second wall (24) of the downstream hook (22b).

6. Assembly according to any one of the preceding claims, wherein the sealing ring (30) comprises an annular platform (31) having a radially internal face and a radially external face, the abradable element being carried by the radially internal face of the annular platform (31), and wherein the upstream attachment means (33a) and the downstream attachment means (33b) each comprise an L-shaped connecting portion (35) fixed to the radially external face of the annular platform (31) of the sealing ring (30).

7. Assembly according to any one of the preceding claims, wherein the stop means are formed by at least one tool (100) fixed to the external housing (20), the tool being arranged downstream of the sealing ring (30) and comprising a first bearing face (102) bearing axially upstream (AM) on the sealing ring (30).

8. Assembly according to the preceding claim, wherein the first bearing face (102) of the tooling (100) is in contact with the hooking portion of the downstream hooking means (33b).

9. Assembly according to the preceding claim, in combination with claim 2, wherein the first bearing face (102) of said at least one tool (100) is axially supported upstream (AM) on the middle arm (34c) of the hooking portion (34) of the downstream hooking means (33b) of the sealing ring (30).

10. Assembly according to claims 6 and 7, wherein the first bearing face (102) of said at least one tool (100) is axially supported on a downstream edge of the annular platform (31).

11. Assembly according to any one of claims 7 to 10, wherein the outer casing (20) comprises a downstream flange (25), preferably radial, and wherein said at least tooling (100) comprises a second bearing face (104) bearing axially upstream (AM) on a downstream face of the downstream flange (25) of the outer casing (20), the second bearing face (104) being preferably arranged radially outward with respect to the first bearing face (102).

12. An assembly according to the preceding claim, wherein the downstream flange (25) of the outer casing (20) comprises one or more scallops (26) distributed, preferably regularly, around the axis (X1), each scallop (26) comprising a hole (27) passing through it in the axial direction (X), and wherein said at least one tool (100) comprises one or more threaded rods (110) extending from the second bearing face (104) of the radially external part (103), through the hole (27) of a scallop (26) associated among said one or more scallops (26) of the downstream flange (25) of the outer casing (20), said at least one tool (100) further comprising a nut (111) associated with each threaded rod (110), each nut (111) being screwed onto the threaded rod (110). to be supported and axially tightened on an upstream face of the downstream flange (25) of the external casing (20).

13. Assembly according to any one of claims 1 to 6, wherein comprising an exhaust housing (50) arranged downstream of the outer housing (20) and wherein the stop means are formed by a radial wall (53) of the exhaust housing (50) arranged opposite, or in support, axially of the sealing ring (30), preferably of the hooking portion (34) of the downstream hooking means (33b).

14. Assembly according to the preceding claim, wherein the exhaust housing (50) is fixed to the outer housing (20), preferably by bolting.

15. Assembly according to claim 13 or 14, comprising a gasket (54) having the shape of a corrugated plate, preferably annular, the gasket (54) being axially interposed between the downstream attachment means (33b) of the sealing ring (30) and the radial wall (53) of the exhaust housing (50).

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