ASSEMBLY FOR AN AIRCRAFT TURBOMACHINE, COMPRISING AN EMERGENCY DEVICE FOR MECHANICALLY COUPLING TWO ROTATING PARTS OF THE ASSEMBLY

Abstract

The invention relates to an assembly (100) for an aircraft turbomachine, comprising: - a first (20) and a second (22) rotating part; - a main device (24) for mechanically coupling the first part (20) with the second part (22), - an emergency device (124) for mechanically coupling the first part (20) with the second part (22), comprising: - a first coupling portion (128), fixed on the first part; - a second coupling portion (132) comprising at least one emergency axial stop (134), and, in the normal operating configuration, the emergency axial stop is axially spaced from a complementary axial stop (136) provided on a fixing member (24a) of the main device (24). In addition, in the event of a failure leading to an unwanted axial separation between the two parts, the emergency device switches to an active axial coupling state. Figure for the abstract: Fig. 2.

Description

Title of the invention: ASSEMBLY FOR AN AIRCRAFT TURBOMACHINE, COMPRISING AN EMERGENCY DEVICE FOR MECHANICALLY COUPLING TWO ROTATING PARTS OF THE ASSEMBLY Technical field

[0001] The invention relates to the field of aircraft turbomachines, and more precisely to that of assemblies implementing rotating parts of the turbomachine, mechanically coupled to each other.

[0002] These may be different rotating parts of the turbomachine, and in particular a drive shaft as well as a disc of a turbine or compressor rotor bladed wheel, mechanically coupled to the shaft.

[0003] The invention finds applications in any type of aircraft turbomachine, such as turbojets or turboprops. State of the prior art

[0004] When two rotating parts of a turbomachine are mechanically coupled to each other, in rotation and in translation, the rupture of one of these parts can lead to an unwanted axial displacement of one of these two parts relative to the other. In the case, for example, of a turbine rotor disk, such a rupture can cause this disk to move backwards, while in the case of a compressor rotor disk, this disk is forced to move forwards. In these two examples, the directions of unwanted axial displacement of the disks are determined by the pressure forces applied to the blades carried by these disks.

[0005] Unwanted axial displacement may result in one of the two parts being forced out of the turbomachine. In order to avoid such a situation, and to meet the reliability and certification requirements in this area, the turbomachine must be able to provide an emergency function, preventing the detached part from being extracted from this turbomachine. This emergency function, also known as "Fail Safe", may be achieved by implementing an emergency device for mechanically coupling the two rotating parts, capable of switching from an inactive coupling state to an active coupling state, in the event of a failure consisting of the breakage of one of these two parts which are integral in rotation. The emergency device makes it possible, in its active coupling state, to form an emergency axial restraint of the part likely to move, thus preventing this part from being extracted from the turbomachine.Usually, this backup device also helps to restore the . rotational coupling of these components, when the main coupling is damaged.

[0006] To produce this emergency device, it may be envisaged to associate a massive axial stop structure with the rotating part likely to undergo the unwanted displacement, by placing this stop structure downstream of the part to be retained in the direction of unwanted axial displacement. However, the dense environment in which the rotating parts of the turbomachine are sometimes located does not allow the installation of such a massive and bulky “Fail Safe” structure. And even if this structure is possible to install, it induces a non-negligible impact on the overall mass of the turbomachine, leading to a reduction in performance, as well as an increase in specific fuel consumption.

[0007] Therefore, there remains a need to improve the design of emergency mechanical coupling devices between rotating turbomachine parts. Statement of the invention

[0008] To meet this need, the invention firstly relates to an assembly for an aircraft turbomachine, comprising:

[0009] - a first turbomachine part as well as a second turbomachine part, each of the first and second parts being rotatable about a longitudinal central axis of the assembly;

[0010] - a main device for mechanically coupling the first part with the second part, the main device allowing, in a normal operating configuration of the assembly, to mechanically couple in translation the first part with the second part, along the longitudinal central axis of the assembly, the main device comprising fixing members spaced circumferentially from each other, and each passing through a first fixing portion of the first part, as well as a second fixing portion of the second part;

[0011] - an emergency device for mechanically coupling the first part with the second room.

[0012] According to the invention, the emergency device comprises:

[0013] - a first coupling portion, fixed to the first part or integrated therein;

[0014] - a second coupling portion comprising at least one emergency axial stop, said second coupling portion being crossed by the fixing members and spaced from the first coupling portion along the longitudinal central axis, and, in the normal operating configuration of the assembly in which the emergency device adopts an inactive axial coupling state, the emergency axial stop is axially spaced from a complementary axial stop provided on one of the fixing members;

[0015] the assembly being configured so that in the event of failure leading to a unwanted axial spacing between the first and second parts, the emergency device switches to an active axial coupling state in which it ensures the axial retention of one of the first and second parts relative to the other, by the emergency axial stop coming into contact with the complementary axial stop.

[0016] The invention thus provides a simple and reliable solution for ensuring an emergency axial retaining function, in the event of a failure which may take the form of a break in the first rotating part, between the first and second coupling portions of the emergency device.

[0017] Furthermore, with this design, the emergency device can advantageously have a low mass. The invention is therefore the result of technological research aimed at significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of these aircraft (decarbonization). The low mass results in particular from the compactness of the assembly, provided in part by the fact of using the same fixing members, such as bolts, both in the normal operating configuration and in the event of failure.

[0018] The invention preferably provides at least any one of the following optional technical features, implemented in isolation or in combination.

[0019] Preferably, the mechanical coupling backup device comprises a shaft, preferably centered on the longitudinal central axis.

[0020] Preferably, the second coupling portion of the emergency device comprises a flange, one axial face of which forms the emergency axial stop, or an annular row of emergency axial stops cooperating respectively with an annular row of complementary axial stops provided on the fixing members.

[0021] Preferably, the main mechanical coupling device also makes it possible, in the normal operating configuration of the assembly, to mechanically couple in rotation the first part with the second part, along the longitudinal central axis of the assembly. In addition, the emergency device also comprises at least one emergency circumferential stop, and, in the normal operating configuration of the assembly in which the emergency device adopts an inactive state of rotational coupling, the emergency circumferential stop is circumferentially spaced from a complementary circumferential stop provided on one of the fixing members;

[0022] the assembly being configured so that in the event of a failure leading to an unwanted relative rotation between the first and second parts, the emergency device switches to an active rotational coupling state in which it ensures rotational coupling of one of the first and second parts with the other, by contacting the emergency circumferential stop with the complementary circumferential stop.

[0023] According to a preferred embodiment of the invention, the second coupling portion also comprises said emergency circumferential stop, preferably taking the form of a part of the delimiting surface of a passage orifice through the flange of the emergency device, each passage orifice being crossed by one of the fixing members.

[0024] Thus, with this design, the same emergency device is further functionalized, since it is advantageously capable of fulfilling an additional “Fail Safe” function of rotational coupling of the two rotating parts.

[0025] Preferably, the emergency axial stop and the emergency circumferential stop are formed by two surfaces of the flange of the emergency device, and the complementary axial stop and the complementary circumferential stop are formed by two surfaces of the same fixing member.

[0026] Preferably, the complementary axial stop and the complementary circumferential stop are respectively formed by a backup axial surface of a fixing member, and by a lateral surface of this same fixing member, the latter comprising a main axial surface forming a support on the first part to grip the latter with the second part in the normal operating configuration of the assembly. This feature simplifies the design of the assembly according to the invention, and makes it more compact.

[0027] Preferably, the first fixing portion of the first part is a fixing flange arranged axially between the flange of the emergency device and the second part.

[0028] The first coupling portion of the emergency device is preferably fixed to the first part using a threaded or welded connection, preferably centered on the longitudinal central axis. A solution where the emergency device would be integrated into the first part, namely made in a single piece with it, is also conceivable. Preferably, in the case of a threaded connection, the direction of screwing of the first coupling portion of the emergency device, on the first part, corresponds to a direction of rotation of the first part, along the longitudinal central axis. Also, in the event of failure and when the second part is driving in rotation within the assembly, the proposed solution avoids the unscrewing of the first coupling portion of the emergency device.

[0029] Preferably, the second part drives the first part in rotation, in a direction of rotation of the first and second parts.

[0030] Preferably, the first part is a drive shaft of the turbomachine, and the second part is a disc of a rotor bladed wheel, preferably a turbine or compressor. However, it could be other coupled rotating parts of the turbomachine, without departing from the scope of the invention.

[0031] Finally, the invention relates to an aircraft turbomachine, comprising at least one assembly as described above. It may for example be a turbojet, and preferably a double-flow and single or double-spool one.

[0032] Other advantages and characteristics of the invention will appear in the detailed non-limiting description below. Brief description of the drawings

[0033] The following detailed description refers to the attached drawings in which:

[0034] [Fig-1] is a schematic view in longitudinal section of a turbomachine aircraft;

[0035] [Fig.2] is a schematic view in longitudinal section of an assembly intended to equip the turbomachine shown in the preceding figure, the assembly being in the form of a preferred embodiment of the invention, shown in normal operating configuration;

[0036] [Fig.3] is a sectional view taken along line III-III of [Fig.2];

[0037] [Fig.4] is a schematic longitudinal sectional view similar to that of [Fig.2], with the assembly shown in the failure configuration;

[0038] [Fig.5] is a sectional view taken along line VV of [Fig.4]. Detailed description of embodiments

[0039] Referring firstly to [Fig.l], an aircraft turbomachine 1 is shown. This is a double-flow, double-spool turbojet engine. However, it could be a turbomachine of another type, for example a single-spool turbojet engine, or even a turboprop, without departing from the scope of the invention.

[0040] The turbomachine 1 has an axis X around which its various components extend, this axis being called the longitudinal central axis of the turbomachine. It comprises, from upstream to downstream along a main direction 5 of flow of the gases through this turbomachine, a fan 3, a low-pressure compressor 4, a high-pressure compressor 6, a combustion chamber 11, a high-pressure turbine 7 and a low-pressure turbine 8.

[0041] Conventionally, after passing through the blower, the air divides into a central primary flow 12a and a secondary flow 12b which surrounds the primary flow. The primary flow 12a flows in a main gas circulation vein 14a passing through the compressors 4, 6, the combustion chamber 11 and the turbines 7, 8. The secondary flow 12b flows in a secondary vein 14b delimited radially outwards by a motor casing, surrounded by a nacelle 9.

[0042] Figures 2 to 5 represent an assembly 100 intended to equip the turbomachine shown in [Fig.l], and presented in the form of a preferred embodiment of the invention.

[0043] This assembly 100 comprises any two rotating parts, coupled mechanically mechanically to each other. The two parts 20, 22 are concentric, with axis X, and here arranged so that the first part 20 is upstream of the second part 22. The two parts 20, 22 are thus rotatable around the axis X, also corresponding to the longitudinal central axis of the assembly 100. In this preferred embodiment of the invention, it is considered that the second part 22 is driving, while the first part 20 is driven in rotation by this second part 22. An inverse situation could nevertheless be retained, without departing from the scope of the invention. For information purposes, the first part 20 here corresponds to a drive shaft of the turbomachine, for example the low pressure shaft of the turbomachine, while the second part 22 corresponds to a disk of a turbine rotor bladed wheel, for example the rotor disk of the last stage of the low pressure turbine 8, namely the disk located furthest downstream within the turbomachine.Other applications remain possible, however, such as having the second driving part 22 corresponding to the low pressure shaft, and the first driven part 20 corresponding to a disc of a compressor rotor bladed wheel, for example the rotor disc of the first stage of the low pressure compressor, namely the disc located furthest upstream within the turbomachine.

[0044] In the case which will be considered below, namely that in which the first driven part 20 corresponds to the low pressure shaft, and the second driving part 22 corresponds to a disc of a rotor bladed wheel of a last stage of the low pressure turbine, the pressure forces resulting from the primary flow and applied to the second part 22 tend to force the latter axially downstream, relative to the first part 20.

[0045] To ensure the axial retention of these two parts 20, 22 relative to each other, the assembly 100 comprises a main device 24 for mechanically coupling the first part 20 with the second part 22. This device 24 here takes the form of an annular ring of fixing members 24a of the bolt type, or similar fixing members, the ring being preferably centered on the axis X. These fixing members 24a, preferably oriented axially, each first pass through a through-orifice 23 of a fixing flange 25 provided on a downstream end portion 38 of the shaft 20. After passing through this fixing flange 25, oriented radially outwards, each bolt 24a passes through a through-orifice 23a provided on the disc 22. The bolts 24a, spaced circumferentially from each other around of the X axis, therefore axially enclose the fixing flange 25 and the disc 22.

[0046] As a result, the fixing flange 25 forms a first fixing portion of the shaft 20, while the part of the disc which delimits the through orifice 23a, forms a second fixing portion 22' of this disc 22.

[0047] In the normal operating configuration of the assembly 100, shown in FIGS. 2 and 3, the main device 24 makes it possible to mechanically couple in translation the first part 20 with the second part 22, along the axis X. It also makes it possible to mechanically couple in rotation these two parts 20, 22, still along the longitudinal central axis X, thanks to the axial tightening of the bolts 24a.

[0048] To do this, each bolt 24a comprises a screw with a shank 58 passing through the two orifices 23, 23a. On the side of the downstream end face of the turbine disk 22, the threaded portion of the shank cooperates with a nut 62, bearing axially on this downstream end face. In addition, on the side of the fixing flange 25, the shank has a widened portion 64 defining an axial shoulder, which forms a main axial surface 66, bearing on the upstream end surface of the fixing flange 25. Thus, in the normal operating configuration of the assembly, the main axial surface 66 of the screw and the nut 62 are tensioned so as to axially grip the two parts 20, 22.

[0049] It is noted that the through hole 23 is crossed by the barrel 58 of the screw with simply a mounting clearance, or without clearance.

[0050] The assembly 100 also comprises a backup device 124 for mechanically coupling the first part 20 with the second part 22, of a design specific to the present invention. This backup device 124, also called a “Fail Safe” device, makes it possible to deal with a failure case corresponding to a break on the downstream end portion 38 of the first part 20. The backup device 124 in fact makes it possible to deal with any failure case likely to lead to an unwanted axial displacement of the second part 22 downstream relative to the first part 20, and more generally any failure case likely to lead to an unwanted axial separation between these two parts 20, 22.

[0051] More precisely, the emergency device 124, arranged around the shaft 20, comprises a shaft 126, hollow or solid, centered on the axis X. At its upstream end, the shaft 126 carries a first coupling portion 128, fixed to the first part 20, preferably using a threaded or welded connection 130, also centered on the axis X. This threaded connection 130 is therefore preferably provided outside the hollow engine shaft forming the first turbomachine part 20. In the screwed solution, the direction of screwing of the first coupling portion 128, on the first part 20, corresponds to the direction of rotation of the two parts 20, 22 in the normal operating configuration. Therefore, in the event of failure, with the second driving part 22 rotating the emergency device 124, there is no risk that this rotation will cause the first coupling portion 128 of this emergency device 124 to unscrew.

[0052] At its downstream end, the shaft 126 carries a second coupling portion 132 comprising at least one emergency axial stop 134. The second coupling portion 132 is spaced from the first coupling portion 128, along the X axis. Indeed, the first coupling portion 128 is preferably located at the same axial level as a rolling bearing 40 supporting the shaft 20, or close to this bearing 40. Here, the bearing 40 indirectly supports the shaft 20, via the emergency device 124, around which the bearing 40 is directly mounted.

[0053] The first coupling portion 128, which is therefore preferably threaded, can extend upstream beyond the most downstream rolling bearing 40. The second coupling portion 132 is, for its part, preferably located near an upstream end of the downstream end portion 38 of the shaft 20, formed by the fixing flange 25. Also, the emergency device 124 is provided to ensure the “Fail Safe” function in the event of breakage of the shaft 20 occurring in an area located axially between the two coupling portions 128, 132 of the emergency device. This amounts to considering, in the preferred embodiment which is described, that the emergency device 124 is capable of ensuring the “Fail Safe” function in the event of breakage of the shaft 20 occurring axially at any location on its downstream end portion 38, that is to say downstream of the bearing 40 or the threaded connection 130.

[0054] The emergency device 124 implemented in this preferred embodiment is such that it makes it possible to provide emergency axial retention, as well as emergency rotational coupling between the two parts 20, 22, in the event of breakage of the shaft at its downstream end portion 38.

[0055] At its downstream end, the shaft 126 therefore carries the second coupling portion 132, which comprises a flange 133 extending radially outwards, and an upstream axial face of which forms an annular row of emergency axial stops 134. More precisely, the flange 133 has passage orifices 68 crossed with clearance by the bolts 24a. More precisely, it is the enlarged portion 64 of each barrel 58 which is housed in one of the passage orifices 68. Also, the emergency axial stops 134 are formed on the upstream axial face of the flange, by the surfaces at the level of which the passage orifices 68 open, these surfaces being able to be considered as annular or substantially annular around each orifice 68. They are designed to cooperate with an annular row of complementary axial stops 136, provided on the bolts 24a.More precisely, each complementary axial stop 136 is formed by an axial relief surface provided on the corresponding fixing member 24a. As can be seen in [Fig. 2], this axial relief surface 134 is located between the screw head 72 and the widened portion 64 of the barrel, and corresponds more precisely to the downstream axial surface of the screw head 72, from which the widened portion extends, downstream.

[0056] Furthermore, the flange 133 of the second coupling portion 132 comprises an annular row of emergency circumferential stops 234. Each of these stops 234 is produced by a part of the delimiting surface of one of the passage orifices 68 through the flange 133. More precisely, this part 234 corresponds to an angular sector of the delimiting surface of this passage orifice 68. This is the angular sector located at a circumferential end of the orifice 68, namely that in the direction of rotation 54 of the two parts 20, 22.

[0057] One of the particularities of this embodiment therefore lies in the fact that an emergency axial stop 134, and an emergency circumferential stop 234, are formed by two surfaces of the flange 133. The latter is arranged in such a way that the fixing flange 25 of the shaft 20 is situated axially between this flange 133 of the emergency device 124, and the upstream end surface of the turbine disk 22.

[0058] In a manner similar to that set out above, a complementary axial stop 136 and a complementary circumferential stop 236 are formed by two surfaces of the same bolt 24a. In fact, the complementary axial stop 136 corresponds to the downstream surface of the screw head 72 as indicated previously, while the complementary circumferential stop 236 corresponds to a part of a lateral surface delimiting the widened portion 64 of the screw shank. More precisely, this part 236 corresponds to an angular sector of the lateral surface delimiting the widened portion 64. This is the angular sector located at a circumferential end of the shank, namely that in the direction of rotation 54 of the two parts 20, 22.

[0059] In the normal operating configuration of the assembly 100, shown in FIGS. 2 and 3, the emergency device 124 adopts inactive states of axial coupling and rotational coupling.

[0060] In these inactive states, the axial clearance 137 is retained between the emergency axial stop 134 and the complementary axial stop 136, as well as a circumferential clearance 237 between the emergency circumferential stop 234 and the complementary circumferential stop 236. A radial clearance is also preferably provided between the enlarged portion 64 of each screw barrel 58 and its corresponding passage orifice 68.

[0061] In a failure case corresponding to a rupture within the downstream end portion 38 of the shaft 20, shown diagrammatically in [Fig. 4], the pressure forces applied to the rotor of the disc 22 lead to an unwanted axial separation between the two parts 20, 22. More precisely, this separation is caused by the downstream movement of the disc 22. Simultaneously, an unwanted relative rotation occurs between the first and second parts 20, 22, the disc 22 being momentarily no longer able to drive the shaft in rotation in the direction 54.

[0062] After this break, the shaft 20, which remains axially fixed within the assembly 100, is no longer able to ensure the axial retention of the second part 22 via the bolts. The main mechanical coupling device 24 thus passes into an inactive state of coupling between the two parts, while the aforementioned axial clearance 137 is consumed. during the parasitic axial displacement downstream of the disc 22, taking with it the broken part of the downstream end of the shaft 20. In addition, the pressure forces applied to the rotor cause its disc 22 to continue its rotation, which has the consequence that the circumferential clearance 237 is also consumed due to the relative rotation with the shaft 20, which is momentarily no longer driven in the direction 54.

[0063] These small axial and circumferential movements are stopped by the emergency axial stop 134 coming into contact with the complementary axial stop 136 in motion, as well as by the emergency circumferential stop 234 coming into contact with the complementary circumferential stop 236 in rotational motion with the disc 22. This forces the emergency device 124 to pass from its inactive states to its active states of emergency axial coupling and emergency rotational coupling, shown in Figures 4 and 5.

[0064] Once these active states have been adopted, the emergency device 124 allows the axial retention of the disc 22 by the shaft 20, as well as the rotational driving of the second by the first.

[0065] To facilitate this rotation, one or more centerings 56 may be provided between the shaft 20 and the emergency device 124, preferably located here outside the shaft.

[0066] This reliable, space-saving and low-mass solution thus avoids excessive axial displacement of the second part 22 in the event of failure, and above all prevents this part from escaping axially outside the turbomachine.

[0067] Finally, it is noted that the solution proposed by the present invention is also advantageous in the sense that the emergency device 124 does not require, for its installation in the assembly 100, any modification of the disc 22. In addition, the mounting of the emergency device 124 on the shaft 20 remains easy. In addition, the fact of using the bolts 24a both for the normal operating configuration, and the case of failure, makes it possible to accentuate the compactness of the assembly.

[0068] Various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples, and the scope of which is defined by the appended claims.

Claims

Claims

1. Assembly (100) for an aircraft turbomachine (1), comprising: - a first turbomachine part (20) and a second turbomachine part (22), each of the first and second parts being rotatable about a longitudinal central axis (X) of the assembly; - a main device (24) for mechanically coupling the first part (20) with the second part (22), the main device making it possible, in a normal operating configuration of the assembly, to mechanically couple in translation the first part (20) with the second part (22), along the longitudinal central axis (X) of the assembly, the main device (24) comprising fastening members (24a) spaced circumferentially from each other, and each passing through a first fastening portion (133) of the first part, as well as a second fastening portion (22') of the second part (22); - an emergency device (124) for mechanically coupling the first part (20) with the second part (22), characterized in that the emergency device (124) comprises: - a first coupling portion (128), fixed to the first part (20) or integrated therein; - a second coupling portion (132) comprising at least one emergency axial stop (134), said second coupling portion being crossed by the fixing members (24a) and spaced from the first coupling portion along the longitudinal central axis (X), and, in the normal operating configuration of the assembly in which the emergency device adopts an inactive axial coupling state, the emergency axial stop (134) is axially spaced from a complementary axial stop (136) provided on one of the fixing members (24a); the assembly being configured so that in the event of failure leading to an unwanted axial separation between the first and second parts (20, 22), the emergency device (124) switches to an active axial coupling state in which it ensures the axial retention of one of the first and second parts relative to the other, by contacting the emergency axial stop (134) with the complementary axial stop (136).

2. Assembly according to claim 1, characterized in that the mechanical coupling emergency device (124) comprises a shaft (126), preferably centered on the longitudinal central axis (X).

3. Assembly according to claim 1 or 2, characterized in that the second coupling portion (132) of the emergency device (124) comprises a flange (133) one axial face of which forms the emergency axial stop (134), or an annular row of emergency axial stops (134) cooperating respectively with an annular row of complementary axial stops (136) provided on the fixing members (24a).

4. Assembly according to any one of the preceding claims, characterized in that the main mechanical coupling device (24) also makes it possible, in the normal operating configuration of the assembly, to mechanically couple in rotation the first part (20) with the second part (22), along the longitudinal central axis of the assembly (X), and in that the emergency device (124) also comprises at least one emergency circumferential stop (234), and, in the normal operating configuration of the assembly in which the emergency device (124) adopts an inactive state of rotational coupling, the emergency circumferential stop (234) is circumferentially spaced from a complementary circumferential stop (236) provided on one of the fixing members (24a);the assembly being configured so that in the event of a failure leading to an unwanted relative rotation between the first and second parts (20, 22), the emergency device (124) switches to an active rotational coupling state in which it ensures the rotational coupling of one of the first and second parts with the other, by contacting the emergency circumferential stop (234) with the complementary circumferential stop (236).;

5. An assembly according to claim 4, combined with claim 3, characterized in that the second coupling portion (132) comprises the emergency circumferential stop (234), preferably taking the form of a part of the delimiting surface of a passage orifice (68) through the flange (133) of the emergency device (124), each passage orifice (68) being crossed by one of the fixing members (34a).

6. Assembly according to claim 5, characterized in that the emergency axial stop (134) and the emergency circumferential stop (234) are formed by two surfaces of the flange (133) of the emergency device (124), and in that the complementary axial stop (136) and the complementary circumferential stop (236) are formed by two surfaces of the same fixing member (24a).

7. Assembly according to claim 6, characterized in that the complementary axial stop (136) and the complementary circumferential stop (236) are respectively formed by a backup axial surface of a fixing member (24a), and by a lateral surface of this same fixing member, the latter comprising a main axial surface (66) forming a support on the first part (20) to grip the latter with the second part (22) in the normal operating configuration of the assembly.

8. Assembly according to any one of the preceding claims combined with claim 3, characterized in that the first fixing portion of the first part (20) is a fixing flange arranged axially between the flange (133) of the emergency device (124), and the second part (22).

9. Assembly according to any one of the preceding claims, characterized in that the first coupling portion (128) of the emergency device (124) is fixed to the first part (20) using a threaded (130) or welded connection, preferably centered on the longitudinal central axis (X), and in that in the case of a threaded connection, the direction of screwing of the first coupling portion (128) of the emergency device (124), on the first part (20), corresponds to a direction of rotation (54) of the first part (20), along the longitudinal central axis (X).

10. Assembly according to any one of the preceding claims, characterized in that the second part (22) drives the first part (20) in rotation, in a direction of rotation (54) of the first and second parts (20, 22).

11. Aircraft turbomachine (1), comprising at least one assembly (100) according to any one of the preceding claims, the first part (20) preferably being a drive shaft of the turbomachine, and the second part (22) preferably being a disc of a rotor bladed wheel, preferably of a turbine (7, 8) or of a compressor (4, 6).

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