Aircraft turbomachine assembly, including a backup 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 rotating part (22); - a main device (24) for mechanically coupling the first part (20) with the second part (22); - a backup device (124) for mechanically coupling the first part (20) with the second part (22), comprising: - a first coupling portion (128), fixed to the first part; - a second coupling portion (132) comprising at least one backup axial stop (134), and, in the normal operating configuration, the backup axial stop is axially separated from a complementary axial stop (136) provided on the first part. Furthermore, the assembly is configured such that in the event of a failure leading to an undesired axial separation between the first and second parts, the backup device enters an active axial coupling state. Figure for the abstract: Fig. 2.

Description

Title of the invention: AIRCRAFT TURBOMACHINE ASSEMBLY, COMPRISING A MECHANICAL COUPLING EMERGENCY DEVICE FOR TWO ROTATING PARTS OF THE ASSEMBLY technical field

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

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

[0003] The invention finds applications in all types of aircraft turbomachinery, such as turbojets or turboprops. Prior art

[0004] When two rotating parts of a turbomachine are mechanically coupled together in rotation and translation, the failure of one of these parts can lead to an undesired axial displacement of one of the two parts relative to the other. In the case, for example, of a turbine rotor disk, such a failure can cause this disk to move backward, while in the case of a compressor rotor disk, this disk is forced to move forward. In both examples, the directions of undesired axial displacement of the disks are determined by the pressure forces acting on the blades carried by these disks.

[0005] Unwanted axial displacement can result in one of the two parts being forced out of the turbomachine. To avoid such a situation, and to meet the relevant reliability and certification requirements, the turbomachine must be able to provide a failsafe function, preventing the detached part from being extracted from the turbomachine. This failsafe function, also known as "Fail Safe," can be implemented by installing a mechanical coupling device for the two rotating parts. This device can switch from an inactive coupling state to an active coupling state in the event of a failure consisting of the breakage of one of the two rotating parts. In its active coupling state, the failsafe device provides an axial restraint for the part that could move, thus preventing it from being extracted from the turbomachine.Usually, this backup system also allows for the restoration of the . rotational coupling of these components when the main coupling is damaged.

[0006] To implement this backup device, it could be considered to associate a massive axial arresting structure with the rotating part likely to undergo the unwanted movement, by placing this arresting structure downstream of the part to be restrained in the direction of the unwanted axial movement. However, the dense environment in which the rotating parts of the turbomachine are sometimes located does not allow for the implementation of such a massive and bulky "fail-safe" structure. And even if such a structure could be implemented, it would have a significant impact on the overall mass of the turbomachine, leading to a decrease in performance, as well as an increase in specific fuel consumption.

[0007] Consequently, there remains a need to improve the design of the backup mechanical coupling devices between the rotating parts of the turbomachine. Description of the invention

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

[0009] - a first turbomachine part and a second turbomachine part, each of the first and second parts being rotatable around a central longitudinal 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;

[0011] - a backup mechanical coupling device for the first part with the second piece.

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

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

[0014] - a second coupling portion comprising at least one emergency axial stop, said second coupling portion being 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 said first part;

[0015] the assembly being configured so that in the event of a failure leading to an undesired axial separation between the first and second parts, the backup 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 bringing the backup axial stop into contact with the complementary axial stop.

[0016] The invention thus provides a simple and reliable solution to ensure an emergency axial restraint 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 aircraft performance and, in this sense, contributes to reducing the environmental impact of these aircraft (decarbonization).

[0018] The invention preferably provides for at least one of the following optional technical features, implemented individually 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 whose axial face forms the emergency axial stop, or an annular row of emergency axial stops.

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

[0022] the assembly being configured so that in the event of a failure leading to an undesired relative rotation between the first and second parts, the backup device 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 bringing the emergency circumferential stop into contact with the complementary circumferential stop.

[0023] According to a preferred embodiment of the invention, the second coupling portion also includes said circumferential emergency stop.

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

[0025] Preferably, the axial emergency stop and the circumferential emergency stop are formed by two surfaces of the same first component of the emergency device, and the The complementary axial stop and the complementary circumferential stop are formed by two surfaces of the same second component of the first part.

[0026] Preferably, the first component is a tooth, groove, or slot projecting radially within the flange of the emergency device, and the second component is a coupling recess, or vice versa, and the first component is housed in the coupling recess when the emergency device is in its active and inactive axial coupling and rotational coupling states. This feature simplifies the design of the assembly according to the invention.

[0027] Preferably, the flange of the emergency device comprises several radially projecting first elements, circumferentially spaced from one another, and the first part comprises several coupling recesses, each housing one of the first elements. The first part includes a mounting flange through which mounting elements pass, forming the main mechanical coupling device. The first elements of the emergency device are arranged circumferentially, alternating with the mounting elements of the main device. This particular arrangement further enhances the compactness of the assembly.

[0028] The first coupling portion of the backup device is preferably fixed to the first part by means of, for example, a welded connection, preferably centered on the longitudinal central axis. A solution where the backup device is integrated into the first part, i.e., made as a single piece with it, is also conceivable.

[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 second component is the coupling recess, and the complementary circumferential stop corresponds to a circumferential boundary surface of this recess, and the complementary axial stop corresponds to an axial base of this recess. Also, in the event of a failure and when the second part is rotating within the assembly, the proposed solution allows the emergency circumferential stop to automatically come into contact with the complementary circumferential stop, through relative rotational movement between the second driving part and the second coupling portion of the emergency device attached to the first driven rotating part.

[0031] Preferably, the first part is a drive shaft of the turbomachine, and the second part is a disc of a bladed rotor wheel, preferably of a turbine or compressor. However, it could be other rotating parts coupled to the turbomachine, without departing from the scope of the invention.

[0032] Finally, the invention relates to an aircraft turbomachine, comprising at least one assembly as described above. This could, for example, be a turbojet engine, and preference for dual-flow and single or dual-body systems.

[0033] Other advantages and features of the invention will appear in the detailed, non-limiting description below. Brief description of the drawings

[0034] The detailed description that follows refers to the accompanying drawings in which:

[0035] [Fig-1] is a schematic longitudinal cross-sectional view of a turbomachine aircraft;

[0036] [Fig.2] is a schematic longitudinal sectional view of an assembly intended to equip the turbomachine shown in the previous figure, the assembly being in the form of a preferred embodiment of the invention, shown in normal operating configuration;

[0037] [Fig.3] is a cross-sectional view taken along line III-III of [Fig.2];

[0038] [Fig.3A] is a cross-sectional view taken along line IIIA-IIIA of [Fig.3];

[0039] [Fig.4] is a schematic longitudinal sectional view similar to that of [Fig.2], with the assembly shown in failure configuration;

[0040] [Fig.5] is a cross-sectional view taken along line VV of [Fig.4]. Detailed description of implementation methods

[0041] With reference first to [Fig. 1], an aircraft turbomachine 1 is shown. This is a twin-spool turbofan engine. However, it could be a turbomachine of another type, for example a single-spool turbofan engine, or even a turboprop, without departing from the scope of the invention.

[0042] 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 blower 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.

[0043] Conventionally, after passing through the blower, the air splits into a central primary flow 12a and a secondary flow 12b which surrounds the primary flow. The primary flow 12a flows into a main gas circulation channel 14a passing through the compressors 4, 6, the combustion chamber 11 and the turbines 7, 8. The secondary flow 12b, on the other hand, flows into a secondary channel 14b delimited radially outwards by an engine casing, surrounded by a nacelle 9.

[0044] Figures 2 to 5 represent an assembly 100 intended to equip the turbomachine shown in [Fig.1], and presented in the form of a preferred embodiment of the invention.

[0045] This assembly 100 comprises any two rotating parts, coupled me mechanically to each other. The two parts 20, 22 are concentric, with axis X, and are 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, which also corresponds to the longitudinal central axis of the assembly 100. In this preferred embodiment of the invention, the second part 22 is considered to be the driving part, while the first part 20 is driven in rotation by this second part 22. A reverse situation could nevertheless be considered, without departing from the scope of the invention. For the sake of reference, 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 disc of a bladed turbine rotor wheel, for example the rotor disc of the last stage of the low pressure turbine 8, namely the disc 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 bladed disc of a compressor rotor wheel, for example the rotor disc of the first stage of the low-pressure compressor, namely the disc located furthest upstream within the turbomachine.

[0046] 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 bladed rotor 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 it axially downstream, relative to the first part 20.

[0047] To ensure axial retention of these two parts 20, 22 relative to each other, the assembly 100 includes a main device 24 for mechanically coupling the first part 20 with the second part 22. This device 24 takes the form of an annular ring of bolt-type fasteners 24a, or similar fasteners, the ring being preferably centered on the X-axis. These fasteners 24a, preferably axially oriented, each first pass through a through hole 23 in a mounting flange 25 provided on a downstream end portion 38 of the shaft 20. After passing through this mounting flange 25, which is radially oriented outwards, each bolt 24a passes through a through hole 23a provided on the disc 22. The bolts 24a, spaced circumferentially from each other around the X axis, therefore axially clamp the fixing flange 25 and the disc 22.

[0048] In the normal operating configuration of the assembly 100, shown in Figures 2 and 3, the main device 24 allows the first part 20 to be mechanically coupled in translation with the second part 22, along the X-axis. It allows also to mechanically couple in rotation these two parts 20, 22, always along the longitudinal central axis X, thanks to the axial tightening of the bolts 24a.

[0049] The assembly 100 also includes a failsafe device 124 for mechanically coupling the first part 20 with the second part 22, of a design specific to the present invention. This failsafe device 124, also called the "Fail Safe" device, makes it possible to cope with a failure case corresponding to a break in the downstream end portion 38 of the first part 20. The failsafe device 124 makes it possible to cope with any failure case likely to lead to an undesired axial displacement of the second part 22 downstream relative to the first part 20, and more generally with any failure case likely to lead to an undesired axial separation between these two parts 20, 22.

[0050] More specifically, the backup 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 by means of a welded connection 130, also centered on the X-axis. Alternatively, it may be a mechanical connection between the two elements, for example made using a pin or similar mechanical elements. This connection 130 is preferably provided inside the hollow drive shaft forming the first turbomachine part 20.

[0051] At its downstream end, the shaft 126 carries a second coupling portion 132 comprising at least one axial emergency 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 bearing 40 supporting the shaft 20, or close to this bearing 40. This first coupling portion 128 can extend upstream beyond the most downstream bearing 40, as shown in Figures 2 and 4. The second coupling portion 132 is, for its part, preferably located at the same axial level as a downstream end of the downstream end portion 38 of the shaft 20, or close to this end.Also, the backup device 124 is designed to ensure the "Fail Safe" function in the event of shaft 20 failure occurring in an area located axially between the two coupling portions 128, 132 of the backup device. This amounts to considering, in the preferred embodiment described, that the backup device 124 is capable of ensuring the "Fail Safe" function in the event of shaft 20 failure occurring axially at any point on its downstream end portion 38, i.e. downstream of the bearing 40 or the welded connection 130.

[0052] The emergency device 124 implemented in this preferred embodiment is such that it makes it possible to ensure emergency axial restraint, as well as emergency rotational coupling between the two parts 20, 22, in the event of breakage of the shaft at its downstream end part 38.

[0053] At its downstream end, the shaft 126 therefore carries the second coupling portion 132, which includes a flange 133 extending radially outwards, and of which an upstream axial face forms an annular row of emergency axial stops 134.

[0054] The flange 133 has a general star or gear shape, in that it comprises a circumferential base 133a from which extend a plurality of first elements 138 of the backup device 124. These first elements 138 are circumferentially spaced from one another, projecting radially outwards from the base 133a of the flange. Each first element 138 is in the form of a tooth, a groove, or a notch. This first element 138 is intended to cooperate with a second element 238, which is in this case a coupling recess provided on a downstream axial end surface of the shaft 20, this recess 238 opening radially inwards and axially downstream.

[0055] Each first member 138 is intended to be housed in a corresponding coupling recess 238, regardless of the states of the backup device 124, i.e. whether it is in its active or inactive axial coupling and rotational coupling states.

[0056] The circumferential succession of impressions 238, linked together at their internal radial ends opened by a recess 238a housing the base 133a of the flange 133, also has a general star or toothed wheel shape, of complementary or substantially complementary shape to that of the flange 133.

[0057] Furthermore, the first components 138 of the backup device 124 are arranged circumferentially, alternating with the bolts 24a of the main device 24, as is most clearly seen in [Fig. 3]. In cross-section such as that shown in this figure, the first components 138 extend radially outwards at least beyond one center of the bolts 24a and their through-holes 23.

[0058] Regarding these first members 138, they therefore define, with their upstream axial face, the annular row of axial emergency stops 134. In parallel, each first member 138 in the form of a tooth, groove or notch, also defines, with a circumferential flank delimiting this tooth, a circumferential emergency stop 234. Consequently, the flange 133 also defines an annular row of circumferential emergency stops 234, with circumferential flanks of its teeth 138. As is most clearly visible in [Fig. 2], the flange 133 is then arranged axially with clearance in an axial space defined between the axial bottom of the recesses 238, and an upstream axial surface of the disc 22.

[0059] One of the particularities of this embodiment therefore lies in the fact that an axial emergency stop 134, and a circumferential emergency stop 234, are formed by two surfaces of the same first element 138 in the shape of a tooth or similar.

[0060] Similarly, a complementary axial stop 136 and a circumferential stop The complementary circumferential stop 236 is formed by two surfaces of the same coupling imprint 238 of the shaft 20. Indeed, the complementary circumferential stop 236 corresponds to a circumferential delimiting surface of this imprint 238, while the complementary axial stop 136 corresponds to an axial bottom of this imprint, open downstream.

[0061] In the normal operating configuration of the assembly 100, shown in Figures 2 and 3, the backup device 124 adopts inactive states of axial coupling, and rotational coupling.

[0062] In these inactive states, each tooth 138 is located in one of the impressions 238. Nevertheless, the axial clearance 137 between the emergency axial stop 134 and the supplementary axial stop 136 is maintained, as well as a circumferential clearance 237 between the circumferential emergency stop 234 and the supplementary circumferential stop 236. A radial clearance is also preferably provided between each first portion 138 and the first piece 20.

[0063] In the event of a failure corresponding to a break in the downstream end portion 38 of the shaft 20, shown schematically in [Fig. 4], the pressure forces applied to the rotor of the disc 22 lead to an undesired axial separation between the two parts 20, 22. More precisely, this separation is caused by the downstream displacement of the disc 22. Simultaneously, an undesired relative rotation occurs between the first and second parts 20, 22, the disc 22 being momentarily unable to drive the shaft in rotation in the direction 54.

[0064] After this break, the shaft 20, which remains axially fixed within the assembly 100, is no longer able to provide axial retention of the second part 22 via the bolts. The main mechanical coupling device 24 thus enters an inactive coupling state between the two parts, while the aforementioned axial play 137 is consumed during the parasitic downstream axial displacement of the disc 22, carrying with it the broken portion of the downstream end of the shaft 20. Furthermore, the pressure forces applied to the rotor cause its disc 22 to continue rotating, with the consequence that the circumferential play 237 is also consumed due to the relative rotation with the shaft 20, which is momentarily no longer driven in the direction 54.

[0065] These small axial and circumferential displacements are stopped by the contact of the emergency axial stop 134 with the moving complementary axial stop 136, as well as by the contact of the emergency circumferential stop 234 with the rotating complementary circumferential stop 236 with the disc 22. This forces the emergency device 124 to move from its inactive states to its active states of emergency axial coupling and emergency rotational coupling, shown in Figures 4 and 5.

[0066] Once these active states are adopted, the backup 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.

[0067] To facilitate this rotation, one or more centering points 56 can be provided between the shaft 20 and the backup device 124, located here preferably inside the shaft.

[0068] This reliable, compact 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.

[0069] Finally, it is noted that the solution proposed by the present invention is also advantageous in that the backup device 124 does not require, for its implantation in the assembly 100, any modification of the disc 22. In addition, the mounting of the backup device 124 on the shaft 20 remains easy, in that the latter can be inserted axially into the hollow of the shaft from downstream, in the direction of upstream, before the mounting of the disc 22 on this same shaft 20.

[0070] Various modifications to the invention described above may be made by a person skilled in the art, solely by way of non-limiting examples, the scope of which is defined by the appended claims. For example, the emergency coupling function in translation could alternatively be achieved solely by the circumferential base 133a of the flange 133 in cooperation with the complementaryly shaped recess 238a on the shaft 20, without departing from the scope of the invention. In this latter case, the teeth 138 and the complementaryly shaped recesses 238 would then be used solely for the emergency coupling function in rotation, again by means of the stops 234, 236.

Claims

Demands

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 enabling, in a normal operating configuration of the assembly, the first part (20) to be mechanically coupled in translation with the second part (22), along the longitudinal central axis (X) of the assembly; - a backup device (124) for mechanically coupling the first part (20) with the second part (22), characterized in that the backup device (124) comprises: - a first coupling portion (128), fixed on 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 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 said first part (20); the assembly being configured so that in the event of a failure leading to 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 it ensures the axial retention of one of the first and second parts relative to the other, by bringing the emergency axial stop (134) into contact with the complementary axial stop (136).

2. Assembly according to claim 1, characterized in that the mechanical coupling backup 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) an axial face of which forms the axial stop of rescue (134), or an annular row of axial rescue stops (134).

4. Assembly according to any one of the preceding claims, characterized in that the main mechanical coupling device (24) also allows, in the normal operating configuration of the assembly, the first part (20) to be mechanically coupled in rotation with the second part (22), along the longitudinal central axis of the assembly (X), and in that the backup device (124) also includes at least one circumferential backup stop (234), and, in the normal operating configuration of the assembly in which the backup device (124) adopts an inactive state of rotational coupling, the circumferential backup stop (234) is circumferentially spaced from a complementary circumferential stop (236) provided on the first part (20);the assembly being configured so that in the event of a failure leading to an undesired relative rotation between the first and second parts (20, 22), the backup device (124) goes into 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 bringing the emergency circumferential stop (234) into contact with the complementary circumferential stop (236).

5. Assembly according to claim 4, characterized in that the second coupling portion (132) includes the circumferential emergency stop (234).

6. Assembly according to claim 5, characterized in that the axial emergency stop (134) and the circumferential emergency stop (234) are formed by two surfaces of the same first element (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 element (238) of the first part (20).

7. Assembly according to claim 6 combined with claim 3, characterized in that the first component (138) is a tooth, groove, or slot projecting radially within the flange of the emergency device, and in that the second component (238) is a mating recess, or vice versa, and the first component (138) is housed in the mating recess (238) when the device rescue (124) is in its active and inactive axial coupling and rotational coupling states.

8. Assembly according to claim 7, characterized in that the flange (133) of the emergency device (124) has several first members (138) projecting radially, spaced circumferentially from each other, and in that the first part (20) has several coupling recesses (238) each housing one of the first members (138), the first part (20) comprising a fixing flange (25) through which fixing members (24a) pass, forming the main mechanical coupling device (24), the first members (138) of the emergency device (124) being arranged circumferentially in alternation with the fixing members (24a) of the main device (24).

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 welded connection (130), preferably centered on 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. Assembly according to claim 10 combined with claim 7, characterized in that the second member (238) is the coupling impression, and in that the complementary circumferential stop (236) corresponds to a circumferential boundary surface of this impression (238), and in that the complementary axial stop (136) corresponds to an axial bottom of this impression (238).

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

Images