WO2025141269A1 - Aircraft turbine engine assembly comprising an emergency device for the mechanical coupling of two rotating parts of the assembly - Google Patents

Abstract

The invention relates to an assembly (100) for an aircraft turbine engine (1), the assembly comprising: - a first turbine engine part (20) and a second turbine engine part (22), wherein each of the parts is rotatable about a longitudinal central axis (X) of the assembly; - a main device (24) for mechanically coupling the first part (20) to the second part (22), wherein the main device is configured, in a normal operating configuration of the assembly, to mechanically couple the first part (20) to the second part (22) in translation along the longitudinal central axis (X) of the assembly; - an emergency device (124) for mechanically coupling the first part (20) to the second part (22), wherein the emergency device (124) comprises a shaft (126) that comprises: - a first coupling portion (128) fixed to or integrated into the first part (20); - a second coupling portion (132) comprising at least one emergency axial stop (134), and, in the normal operating configuration of the assembly, in which the emergency device is in an inactive axial coupling state, the emergency axial stop (134) is axially spaced from a complementary axial stop (136) provided on the second part (22); wherein the assembly is configured such that, in the event of a failure resulting in an undesired axial separation between the first and second parts (20, 22), the emergency device (124) switches to an active axial coupling state in which axial retention of one of the first and second parts relative to the other is ensured by the emergency axial stop (134) coming into contact with the complementary axial stop (136).

Description

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

Technical field

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.

These may be various 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.

The invention finds applications in any type of aircraft turbomachine, such as turbojets or turboprops.

State of the prior art

When two rotating parts of a turbomachine are mechanically coupled to each other, in rotation and in translation, the breakage of one of these parts or the failure of their main mechanical coupling device 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 breakage can cause this disk to move backward, while in the case of a compressor rotor disk, this disk is forced to move forward. 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.

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", can 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 state. coupling in the event of breakage of one of these two parts, or failure of their main mechanical coupling device. The emergency device allows, 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 emergency device also allows the rotational coupling of these components to be restored, when the main coupling is damaged.

To achieve this emergency device, it may be considered 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 implementation of such a massive and bulky "Fail Safe" structure. And even if this structure is possible to implement, 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.

Therefore, there remains a need to improve the design of mechanical coupling backup devices between rotating turbomachine parts.

Statement of the invention

To meet this need, the invention firstly relates to an assembly for an aircraft turbomachine, according to the characteristics of claim 1.

The invention thus provides a simple and reliable solution for ensuring an emergency axial retention function, in the event of a failure which may take the form of either a breakage of one of the two rotating parts, or a failure of their main mechanical coupling device.

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 aircraft performance and, in this sense, contributes to reducing the environmental impact of these aircraft (decarbonization). The invention preferably provides at least any one of the following optional technical features, implemented in isolation or in combination.

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

Preferably, the second coupling portion of the emergency device comprises an annular row of emergency axial stops.

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 the second part; 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 state of rotational coupling in which it ensures the rotational coupling of one of the first and second parts with the other, by the emergency circumferential stop coming into contact with the complementary circumferential stop.

According to a preferred embodiment of the invention, the second coupling portion also comprises said emergency circumferential stop.

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.

Preferably, the emergency axial stop and the emergency circumferential stop are formed by two surfaces of the same first member of the emergency device, and the complementary axial stop and the complementary circumferential stop are formed by two surfaces of the same second member of the second part, the first member being a tooth and the second member being a coupling notch, or vice versa, and the tooth being housed in the coupling notch when the emergency device is in its active states of axial coupling and rotational coupling. This feature simplifies the design of the assembly according to the invention.

Preferably, the coupling notch opens circumferentially onto an axial insertion groove of the tooth. This feature facilitates the manufacture and assembly of the constituent elements of the assembly according to the invention.

According to another preferred embodiment of the invention, the emergency device further comprises a third coupling portion, comprising said emergency circumferential stop, the emergency circumferential stop and the complementary circumferential stop being preferentially defined by facing surfaces of two teeth, grooves or notches.

Preferably, the emergency axial stop is formed by a screw head, a washer or a nut.

Whatever the embodiment envisaged, 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.

Preferably, the screwing direction 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 prevents the unscrewing of the first coupling portion of the emergency device.

Preferably, the second part rotates the first part, in a direction of rotation of the first and second parts.

Preferably, the second member is the coupling notch, and the complementary circumferential stop corresponds to a circumferential bottom of this notch, circumferentially offset by a circumferential notch opening in a direction opposite to the direction of rotation of the first and second parts. Also, in the event of failure and when the second part is driving in rotation within the assembly, the proposed solution makes it possible to automatically obtain the emergency circumferential stop coming into contact with the complementary circumferential stop, by relative rotational movement between the second driving part and the second coupling portion of the emergency device secured to the first driven rotating part.

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.

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 turbojet.

Other advantages and characteristics of the invention will appear in the detailed non-limiting description below.

Brief description of the drawings

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

[Fig. 1] is a schematic longitudinal sectional view of an aircraft turbomachine;

[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 first preferred embodiment of the invention, in normal operating configuration;

[Fig. 3] is a schematic longitudinal sectional view similar to that of the preceding figure, with the assembly shown in the failure configuration;

[Fig. 4] is a half-sectional schematic view of an aircraft turbomachine having another architecture;

[Fig. 5] is an enlarged schematic half-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 second preferred embodiment of the invention, in normal operating configuration;

[Fig. 6] is an exploded perspective view of the second part of the assembly shown in the preceding figure, and of the emergency device for mechanically coupling the two parts; [Fig. 7] is a schematic view showing the emergency device when it adopts its inactive axially coupled and rotationally coupled states;

[Fig. 8] is a schematic half-view similar to that of Fig. 5, with the assembly shown in the failure configuration;

[Fig. 9] is a schematic view similar to that of Fig. 7, showing the emergency device when it adopts its active axially coupled and rotationally coupled states;

[Fig. 10] is a schematic half-view similar to that of Fig. 5, with the assembly being in the form of a third preferred embodiment of the invention, and shown in the normal operating configuration;

[Fig. 10A] is a sectional view taken along line XA-XA of Fig. 10;

[Fig. 11] is a schematic half-view similar to that of Fig. 10, with the assembly shown in the failure configuration;

[Fig. 11A] is a sectional view taken along line XIA-XIA of Fig. 11;

[Fig. 12] is a schematic half-view similar to that of Fig. 10, with the assembly being in the form of an alternative to the third preferred embodiment, and shown in the normal operating configuration;

[Fig. 12A] is a sectional view taken along line XIIA-XIIA of Fig. 12;

[Fig. 13] is a schematic half-view similar to that of Fig. 5, with the assembly being in the form of a fourth preferred embodiment of the invention, and shown in the normal operating configuration;

[Fig. 14] is a schematic view showing the emergency device when it adopts its inactive axially coupled and rotationally coupled states;

[Fig. 15] is a schematic half-view similar to that of Fig. 13, with the assembly shown in the failure configuration; [Fig. 16] is a schematic view similar to that of Fig. 14, showing the emergency device when it adopts its active axially coupled and rotationally coupled states; and

[Fig. 17] is a schematic half-view similar to that of Fig. 13, with the assembly being in the form of an alternative to the fourth preferred embodiment, and shown in the normal operating configuration.

Detailed description of embodiments

Referring firstly to Figure 1, 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.

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 gas flow 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. Conventionally, after passing through the fan, 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 towards the outside by a motor casing, surrounded by a nacelle 9.

Figures 2 and 3 show an assembly 100 intended to equip the turbomachine shown in Figure 1. This assembly 100 comprises any two rotating parts, mechanically coupled 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 about the axis X, also corresponding to the longitudinal central axis of the assembly 100. In this first preferred embodiment of the invention, it is considered that the second part 22 is driving part, 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 may be a drive shaft of the turbomachine, for example the low pressure shaft of the turbomachine, while the second part 22 may be a disk of a turbine rotor bladed wheel, for example the rotor disk of the last stage of the low pressure turbine, namely the disk located furthest downstream within the turbomachine. Other applications are however possible, such as having the second driving part 22 corresponding to the low pressure shaft, and the first driven part 20 corresponding to a disk of a compressor rotor bladed wheel, for example the rotor disk of the first stage of the low pressure compressor, namely the disk located furthest upstream within the turbomachine.

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.

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 crown of bolts, or similar fixing elements passing through fixing flanges provided on each of these two parts. The crown of bolts is preferably centered on the X axis.

In the normal operating configuration of the assembly, shown in Figure 2, 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, always along the longitudinal central axis X.

The assembly 100 also comprises a backup device 124 for mechanically coupling the first part 20 with the second part 22, of specific design to the present invention. This emergency device 124, also called a “Fail Safe” device, makes it possible to deal with a failure case such as the breakage of one of the two rotating parts, such as a breakage at the downstream end of the first part 20, shown in FIG. 3, or even the failure of the main device 24. The emergency device 124 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.

More specifically, the emergency device 124 comprises a shaft 126, hollow or solid, centered on the X axis. 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 X axis. This threaded connection 130 is preferably provided inside the hollow drive 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. As a result, 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 unscrewing of the first coupling portion 128 from this emergency device 124.

At its downstream end, the shaft 126 carries a second coupling portion 132 comprising at least one emergency axial stop 134. This is preferably an annular row of emergency axial stops 134, for example made by teeth or crenellations projecting radially outwards. In the normal operating configuration of the assembly shown in FIG. 2, the emergency device 124 adopts an inactive axial coupling state. This inactive state is materialized by the fact that the emergency axial stop 134 is spaced axially downstream from a complementary axial stop provided on the second part 22. Here, the complementary axial stop 136 corresponds to the upstream lateral flank of an annular groove opening radially inwards into a hollow interior space of the second part 22, corresponding to the space hollow central part usually made on turbine discs, and in which the second coupling portion 132 of the emergency device 124 is located. The upstream part of the part 22 preferably comprises axial grooves for the passage of the teeth 134, during assembly.

An axial clearance 137 is therefore observed in normal operating configuration, between the emergency axial stop 134 and the complementary axial stop 136. A radial clearance is also preferably provided between the complementary axial stop 136 and the part 22.

In a failure case such as one of those described above, and of which the one shown in FIG. 3 corresponds to a rupture of the first part 20 at its downstream end, namely downstream of the threaded connection 130, the pressure forces applied to the second part 22 lead to an undesired axial separation between the two parts. More precisely, this separation is caused by the downstream movement of the second part 22.

After this break, the first part 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, while the aforementioned clearance 137 is consumed during the parasitic axial movement downstream of the second part 22. This small axial movement is stopped by the emergency axial stop 134 coming into contact with the complementary axial stop 136 in motion. This causes the emergency device 124 to pass from its inactive state to an active emergency axial coupling state, in which it ensures the axial retention of the second part 22 by the first part 20.

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.

In this first preferred embodiment of the invention, the mechanical coupling device 24 also forms a main rotational coupling between the parts 20, 22. In this regard, an emergency mechanical rotational coupling is preferably provided. between these two same parts 20, 22, in the event of breakage or failure of the type mentioned above. This ensures continued rotation of the first part 20 by the second part 22, via this emergency device becoming active, and which can take any form deemed appropriate by those skilled in the art.

It is noted that in the normal operating configuration of the assembly in which the emergency device adopts an inactive state of rotational coupling, a rotational coupling zone may have sufficient rotational spacing or clearance, making it possible to consider that the force path created by this coupling is not the preferred path. This path, however, becomes active after rupture/failure and consumption of the circumferential clearance, in a manner identical or similar to that which will be described for the following preferred embodiments.

Referring now to Figures 4 to 9, a second preferred embodiment of the invention is shown, in which the turbomachine 1 has a different architecture from the previous one, comprising a single body. The single compressor 4 is of centrifugal design, while the single turbine 7 remains of axial design. In this second preferred embodiment, the assembly 100 is similar to that of the first preferred embodiment, in that the first part 20 remains a drive shaft, the one connecting the compressor 4 to the turbine 7, to form the single body centered on the axis X. In addition, the second part 22 remains a disk of a turbine rotor bladed wheel, for example the rotor disk of the last stage of the turbine 7, or of the single stage of this turbine, namely the disk 22 located furthest downstream within the turbomachine.

At the downstream end of the shaft 20, the latter is fixed to the disc 22 by the annular ring of bolts, forming the main mechanical coupling device 24 of these two parts 20, 22. The downstream end portion 38 of the shaft 20, which is located between the most downstream rolling bearing 40 which supports this shaft, and the fixing interface with the disc 22, may be subject to breakage. The emergency device 124 implemented in this second 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. Such “Fail Safe” functions are also insured in the event of failure of the 24 bolts, even if this latter type of failure remains less plausible.

The emergency device 124 still comprises the shaft 126, centered on the X axis, and carrying at its upstream end the first coupling portion 128, fixed on the downstream end of the shaft 20 using the threaded or welded connection 130, also centered on the X axis. With the screwed solution, this threaded connection 130 is provided inside the hollow motor shaft 20, still with its screwing direction corresponding to the direction of rotation of the two parts 20, 22 in the normal operating configuration. The first coupling portion 128, which is therefore threaded, can extend upstream beyond the most downstream rolling bearing 40, as shown in Figures 5 and 8.

At its downstream end, the shaft 126 carries the second coupling portion 132, comprising the annular row of emergency axial stops 134, integrated with teeth 138 extending radially inwardly. These are, for example, four teeth 138 regularly distributed around the axis X, and which therefore form first members forming an integral part of the emergency device 124. More precisely, each emergency axial stop 134 corresponds to the upstream surface of a tooth 138, this surface preferably being oriented orthogonally or substantially orthogonally to the axis X.

In addition, each tooth 138 also comprises a circumferential emergency stop 234, corresponding to another surface of this tooth, namely a circumferential end surface adjacent to the previous one, and parallel or substantially parallel to the X axis.

The disc 22 comprises a front extension 50, centered on the axis X and penetrating into the hollow space of the end of the shaft 20. At the level of this front extension 50 of the disc, second members 238 are provided, intended to cooperate with the first members 138 in the form of teeth integrated into the second coupling portion 132 of the emergency device 124. Each second member takes the form of a coupling notch 238 made on the external surface of the front extension of the disc 50, extending in the circumferential direction and being open radially towards the outside. Thus, each complementary axial stop 136 is formed by the front axial flank of one of these coupling notches 238, while this same notch 238 defines, with its circumferential bottom, a complementary circumferential stop 236. As has been shown in FIGS. 7 and 9, the circumferential bottom 236 of each notch 238 is circumferentially offset by a circumferential notch opening 52, in a direction opposite to the direction of rotation 54 of the first and second parts 20, 22.

At this circumferential opening 52 of the notch 238, the latter opens circumferentially onto a groove 55 for axial insertion of the tooth 138. This groove 55, of axial orientation, is open axially towards the front, and radially towards the outside, so as to form jointly with the notch 238 a general L shape. The groove 55 essentially serves to allow the assembly 100 to be mounted.

In the normal operating configuration of the assembly 100, shown in FIG. 7, the emergency device 124 adopts inactive states of axial coupling and rotational coupling.

In these inactive states, each tooth 138 is located in the downstream axial bottom of its associated axial insertion groove 55 as shown in FIG. 7, or is already arranged at least partly in the notch 238. In all cases, 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.

In a failure case such as one of those described above, and of which the one shown in FIG. 8 corresponds to a rupture of the downstream end portion 38 of the shaft 20, the pressure forces applied to the rotor of the disc 22 lead to an unwanted axial separation between the two parts. 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.

After this breakage, 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. main mechanical coupling device 24 thus passes into an inactive state, while the aforementioned axial clearance 137 is consumed during the parasitic axial movement downstream of the disc 22. In addition, the pressure forces applied to the rotor cause its disc 22 to continue its rotation in the direction 54, 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.

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 in direction 54. 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 8 and 9.

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.

To facilitate this rotation, centerings 56 can be provided between the shaft 20 and the emergency device 124, as well as between this same device 124 and the front disk extension 50.

Figures 10 to 11A represent a third preferred embodiment of the invention, falling within the same engine architecture as that of the second embodiment described above.

In this third mode, the emergency device 124 still comprises the first coupling portion 128, fixed to the shaft 20 by the threaded or welded connection 130. The second coupling portion 132 comprises an axial extension 60 passing through the hollow of the disc 22, as well as a stop washer 62 held downstream of this disc by a nut 64, screwed onto the downstream end of the axial extension 60. In the inactive axial coupling state, the axial clearance 137 is indeed provided between the downstream face of the disc 22 forming the complementary axial stop 136, and the upstream surface of the washer 62 located opposite, and forming the emergency axial stop 134. Alternatively, this latter stop 134 could be carried out directly by the nut 64, or by a screw which would be screwed onto the downstream end of the axial extension 60.

One of the particularities here lies in the fact that the emergency device 124 comprises, on the shaft 126 between its first and second portions 128, 132, a third coupling portion 66 to ensure emergency rotational coupling in the event of failure.

More specifically, the third portion 66 comprises emergency circumferential stops 68, formed by surfaces of an annular row of teeth, grooves or crenellations 67 projecting radially outwards. Similarly, the front disc extension 50 comprises complementary circumferential stops 70, formed by surfaces of an annular row of teeth, grooves or crenellations 69 projecting radially inwards, and each disposed between two teeth 67.

In normal operating configuration, the surfaces 68, 70 are opposite each other two by two, with the circumferential clearance 237 provided between them. In the event of failure, this clearance 237, visible in FIG. 10A, is consumed in a manner similar to that explained previously. The contact between the surfaces 68, 70 then causes the emergency device 124 to adopt its active state of rotational coupling of the two parts 20, 22, shown in FIG. 11A.

Figures 12 to 12A show an alternative to the third preferred embodiment just described. This alternative has many similarities to the third embodiment. Here, the front disc extension 50 may be removed or shortened, and replaced by a rear disc extension 50', extending projecting downstream. In addition, the third coupling portion 66, to provide emergency rotational coupling in the event of failure, is integrated with the second coupling part 132, being located in the downstream end portion of the emergency device 124.

Thus, in this alternative, the emergency device 124 still comprises the first coupling portion 128, fixed to the shaft 20 by the threaded or welded connection 130. The second coupling portion 132 comprises the axial extension 60 passing through the hollow of the disc 22, as well as a stop washer 62 held downstream of this disc by a nut 64, screwed onto the downstream end of the axial extension 60. In the inactive axial coupling state, the axial play 137 is provided between the downstream face of the rear disc extension 50' forming the complementary axial stop 136, and the upstream surface of the washer 62 located opposite, and forming the emergency axial stop 134. Alternatively, this latter stop 134 could be produced directly by the nut 64, or by a screw which would be screwed onto the downstream end of the axial extension 60.

The third coupling portion 66 is integrated into the axial extension 60, corresponding to the part located radially under the rear disc extension 50'.

This third portion 66 comprises the emergency circumferential stops 68, formed by surfaces of an annular row of teeth, grooves or crenellations 67 projecting radially outwards. Similarly, the rear disc extension 50' comprises the complementary circumferential stops 70, formed by surfaces of an annular row of teeth, grooves or crenellations 69 projecting radially inwards, and each arranged between two teeth 67.

In normal operating configuration, the surfaces 68, 70 are opposite each other two by two, with the circumferential clearance 237 provided between them. In the event of failure, this clearance 237, visible in FIG. 12A, is consumed in a manner similar to that explained previously. The contact between the surfaces 68, 70 then causes the emergency device 124 to adopt its active state of rotational coupling of the two parts 20, 22, shown in FIG. 12A.

Referring now to Figures 13 to 16, a fourth preferred embodiment of the invention is shown. In this embodiment, the emergency device 124 has the general shape of a pin attached to the shaft 20, projecting radially inwards into the hollow of this shaft. Several of these pin-shaped emergency devices can be provided, for example four pins regularly distributed around the axis X. Only one of them will be described in detail below.

The pin 124 is oriented radially, and it has a generally circular cross-section, or a quadrilateral one as shown in the figures. At its radially outer end, the pin-shaped emergency device 124 comprises the first coupling portion 128, fixed to the downstream end of the shaft 20 using any connection 130, for example threaded or welded. For easy mounting of this pin 124 radially from the outside, the shaft 20 may have a through hole, intended to receive the first coupling portion 128.

At its radially inner end, the pin 124 comprises the second coupling portion 132, projecting radially inwards into the hollow of the shaft 20.

The pin-shaped emergency device 124 forms an emergency axial stop 134. When there are several of them, these pins form an annular row of emergency axial stops 134.

More precisely, each emergency axial stop 134 corresponds to the upstream surface of the second coupling portion 132 of a pin 124, this surface preferably being oriented orthogonally or substantially orthogonally to the X axis, inside the shaft. In the case of a pin with a generally circular cross-section, this surface 134 may be an arc of a circle.

Furthermore, the second coupling portion 132 of the pin 124 also comprises a circumferential emergency stop 234, corresponding to another surface of this radially internal end of the pin, namely a circumferential end surface adjacent to the previous one, and parallel or substantially parallel to the axis X. Here again, in the case of a pin with a generally circular cross-section, this surface 234 may be an arc of a circle.

The disc 22 still comprises the front extension 50, centered on the axis X and penetrating into the hollow space of the end of the shaft 20. At the level of this front extension 50 of the disc, second members 238 are provided, intended to cooperate with the second coupling portions 132 of the pins 124. Each second member takes the form of a coupling notch 238 made on the external surface of the front extension of the disc 50, extending in the circumferential direction and being open radially towards the outside. Thus, each complementary axial stop 136 is formed by the front axial flank of one of these coupling notches 238, while this same notch 238 defines, with its circumferential bottom, a complementary circumferential stop 236. As has been shown in FIGS. 14 and 16, the circumferential bottom 236 of each notch 238 is circumferentially offset by a circumferential notch opening 52, in a direction opposite to the direction of rotation 54 of the first and second parts 20, 22.

At this circumferential opening 52 of the notch 238, the latter opens circumferentially onto a groove 55 for axial insertion of the tooth 138. This groove 55, of axial orientation, is open axially towards the front, and radially towards the outside, so as to form jointly with the notch 238 a general L shape. The groove 55 essentially serves to allow the assembly 100 to be mounted.

In the normal operating configuration of the assembly 100, shown in FIG. 14, the emergency device 124 adopts inactive states of axial coupling and rotational coupling.

In these inactive states, the second coupling portion 132 of each pin 124 is located in the downstream axial bottom of its associated axial insertion groove 55 as shown in FIG. 14, or is already arranged at least partly in the notch 238. In all cases, 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.

In a failure case such as one of those described above, and of which the one shown in Figure 15 corresponds to a rupture of the downstream end portion 38 of the shaft 20, the pressure forces applied to the rotor of the disc 22 lead to an unwanted axial separation between the two parts. 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.

After this breakage, 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. main mechanical coupling device 24 thus passes into an inactive state, while the aforementioned axial clearance 137 is consumed during the parasitic axial movement downstream of the disc 22. In addition, the pressure forces applied to the rotor cause its disc 22 to continue its rotation in the direction 54, 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.

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 in direction 54. 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 15 and 16.

Once these active states have been adopted, each 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. As for the second preferred embodiment described previously, this fourth mode allows the “Fail Safe” functions to be obtained using a dog-type system, formed by the pins 124, as well as the corresponding grooves and notches 55, 238.

Finally, Figure 17 shows an alternative, in which each pin 124 is no longer attached to the shaft 20, but integrated into the latter. Also, the first coupling portion 128 of each pin 124 is made in one piece with the shaft 20, in the thickness thereof. The connection 130 is no longer necessary between the shaft 20 and the first integrated coupling portion 12 of the pin 124, which still includes the second coupling portion 132 projecting radially inwards to cooperate with the front disk extension 50.

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. In addition, all the features disclosed above, in the various preferred embodiments and their alternatives, are combinable with each other. Moreover, it is noted that in all the figures described above, the elements bearing the same numerical references correspond to identical or similar elements.

Claims

1. Assembly (100) for aircraft turbomachine (1), comprising: - a first turbomachine part (20) and a second turbomachine part (22), each of the first and second parts being rotatable around 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 allowing, 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; - 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), 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 said second part (22); the assembly being configured so that in the event of a 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 the emergency axial stop (134) coming into contact with the complementary axial stop (136), the mechanical coupling emergency device (124) comprising a shaft (126). 2. Assembly according to claim 1, characterized in that the shaft (126) is 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 an annular row of emergency axial stops (134). 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 (68, 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 (68, 234) is circumferentially spaced from a complementary circumferential stop (70, 236) provided on the second part (22); 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 (68, 234) with the complementary circumferential stop (70, 236). 5. Assembly according to claim 4, characterized in that the second coupling portion (132) comprises the emergency circumferential stop (234). 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 same first member (138) 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 second member (238) of the second part (22), the first member (138) being a tooth and the second member (238) being a coupling notch, or vice versa, and the tooth (138) being housed in the coupling notch (238) when the emergency device (124) is in its active axial coupling and rotational coupling states. 7. Assembly according to claim 6, characterized in that the coupling notch (238) opens circumferentially onto a groove (55) for axial insertion of the tooth (138). 8. Assembly according to claim 4, characterized in that the emergency device (124) further comprises a third coupling portion (66), comprising said emergency circumferential stop (68), the emergency circumferential stop and the complementary circumferential stop (68, 70) being preferentially defined by facing surfaces of two teeth, grooves or notches (67, 69). 9. Assembly according to claim 8, characterized in that the emergency axial stop (134) is formed by a screw head, a washer (62) or a nut (64). 10. 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). 11. Assembly according to claim 10, characterized in that the direction of screwing of the first coupling portion (128) of the emergency device (124), onto the first part (20), corresponds to a direction of rotation (54) of the first part (20), along the longitudinal central axis (X). 12. 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). 13. Assembly according to claim 12 combined with claim 6, characterized in that the second member (238) is the coupling notch, and in that the complementary circumferential stop (236) corresponds to a circumferential bottom of this notch (238), circumferentially offset by a circumferential notch opening (52) in a direction opposite to the direction of rotation (54) of the first and second parts (20, 22). 14. Assembly according to any one of the preceding claims, characterized in that the first part (20) is a drive shaft of the turbomachine, and in that the second part (22) is a disc of a rotor bladed wheel, preferably of a turbine (7, 8) or of a compressor (4, 6). 15. Aircraft turbomachine (1), comprising at least one assembly (100) according to any one of the preceding claims.