TURBOMACHINE COMPRISING A SPEED REDUCER HAVING FIXING FLANGES CONNECTED TO A STATOR OF THE TURBOMACHINE

Abstract

The invention relates to a speed reducer (20), for an aircraft turbomachine (1) with longitudinal axis X, comprising an external crown (24) and a crown carrier (26) fixed to the external crown, satellite pinions meshing with a sun pinion and the external crown which is formed of two front and rear half-crowns (24a, 24b), these two half-crowns each having respectively a front half-flange (24ab) and a rear half-flange (24bb) extending radially outwards and which are fixed to a fixing flange (27) of the crown carrier, the crown carrier comprising a swan neck (28) allowing the centering of the crown. According to the invention, the fixing flange extends radially between the front half-flange (24ab) and the rear half-flange (24bb) and the swan neck has a C-shaped axial section whose bottom (28a) is tangent to a radial plane (PR) located upstream of the front fixing half-flange. Figure for the abstract: Figure 5

Description

Title of the invention: TURBOMACHINE COMPRISING A SPEED REDUCER HAVING FLANGES FIXINGS CONNECTED TO A STATOR OF THE TURBOMACHINE Field of invention

[0001] The present invention relates to the general field of aeronautics. It relates in particular to a mechanical speed reducer with fixing flanges connected to a stator of the turbomachine. Technical background

[0002] The role of a mechanical reducer is to modify the speed and torque ratio between the input axis and the output axis of a mechanical system.

[0003] New generations of dual-flow turbomachines, particularly those with a high bypass ratio, include a mechanical reducer to drive the shaft of a fan. Usually, the speed reducer aims to transform the so-called fast rotation speed of the shaft of a power turbine into a slower rotation speed for the shaft driving the fan.

[0004] Such a reducer comprises a central pinion, called a sun gear, a crown gear and pinions called satellite gears, which are engaged between the sun gear and the crown gear. The satellite gears are held by a frame called a planet carrier. The sun gear, the crown gear and the planet carrier are planet gears because their axes of revolution coincide with the longitudinal axis X of the turbomachine. The satellite gears each have a different axis of revolution and are equally distributed over the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis X.

[0005] There are several reducer architectures. In the state of the art of double-flow turbomachines, the reducers are of the planetary or epicyclic type. In other similar applications, there are so-called differential or compound architectures. • On a planetary reducer, the planet carrier is fixed and the crown constitutes the output shaft of the device which rotates in the opposite direction to the solar. • On an epicyclic reducer, the crown is fixed and the planet carrier constitutes the output shaft of the device which turns in the same direction as the solar. • On a differential reducer, no element is fixed in rotation. The crown rotates in the opposite direction to the sun and the planet carrier.

[0006] The reducers can be composed of one or more meshing stages. This meshing is ensured in different ways such as by contact, by friction or even by magnetic fields.

[0007] There are several types of contact meshing such as with straight, helical or herringbone teeth.

[0008] Figures 1 and 2 show a speed reducer IA with an epicyclic gear. The speed reducer IA includes a crown 2A which is fixed and which is connected to a fixed housing or stator 3A of the turbomachine via a crown carrier 4A. The speed reducer IA includes satellites 5A which drive a satellite carrier in rotation. The latter is fixed to the blower shaft and is rotatable about the longitudinal axis of the turbomachine. The crown 2A includes a first fixing flange 7A extending radially outwards and fixed to a second fixing flange 8A of the crown carrier 4A by means of a bolted connection. The fixing flanges 7A, 8A each include a surface and these surfaces are clamped against one another by the bolts of the bolted connection. An example of a speed reducer is described in document FR-A1-3042568.

[0009] The crown 2A is formed of two half-crowns 2Aa, 2Ab which comprise internal herringbone teeth meshing with external teeth of the satellites 5A. The two half-crowns also respectively comprise axial teeth 9A which mesh with each other so as to allow the forces to pass from one half-crown to the other during rotation. The two half-crowns 2Aa, 2Ab are positioned precisely relative to each other thanks to an orientation pin which will also allow the alignment of the internal herringbone teeth. A hooping also makes it possible to guarantee the centering of the two half-crowns.

[0010] The crown carrier 4A has bellows for limiting the overloads due to the displacements and misalignment of different components in the turbomachine and for transmitting a large torque. The crown carrier 4A further comprises a swan neck 10A which also aims to ensure the centering of the crowns and to limit the misalignments. The swan neck 10A generally has a small radius of curvature, forming substantially a V and is tangent to a median plane PI passing between the two half-bridges 11Aa, 11Ab of the half-crowns and perpendicular to the longitudinal axis of the turbomachine. For example, the radius of curvature of this swan neck is 5 mm with a V of 45°.

[0011] The passage of the torque is achieved by friction between these surfaces and is limited to the implantation isodiameter. Increasing the diameter of the fixing flanges can be a solution to increase the torque passage capacity. However, on the one hand, the number of screws to be implanted on these flanges can be limited and on the other hand, this could directly impact the diameter of the speed reducer and the integration of the latter in an already restricted space of the turbomachine. Furthermore, the manufacturability of such a crown holder and such a crown is complicated to implement. The holder- The crown wheel includes holes in the bellows for lubricant drainage, which complicates manufacturing and assembly. The swan neck can hinder access to the numerous bolted connections for assembly and removal of the crown wheel carrier and crown wheel. A change to the swan neck results in a change in the stiffness of the crown wheel carrier, which can directly impact gear misalignments.

[0012] There is a need to resolve all or part of the aforementioned drawbacks. Summary of the invention

[0013] The objective of the present invention is to provide a solution which makes it possible to easily connect the crown to the stator of the turbomachine for the transmission of a torque and which is simple and economical to manufacture and assemble, while guaranteeing optimized stiffness.

[0014] We achieve this objective in accordance with the invention by means of a speed reducer for an aircraft turbomachine having a longitudinal axis, the speed reducer comprising a sun gear, planet gears, an external ring gear and a ring gear carrier fixed to the external ring gear, the planet gears being engaged on the one hand with the sun gear and on the other hand with the external ring gear, and the external ring gear being formed of two front and rear half-ring gears which each have respectively a front fixing half-flange and a rear fixing half-flange extending radially outwards and which are fixed to a fixing flange of the ring gear carrier by fixing members, the ring gear carrier comprising a swan neck capable of allowing the centering of the ring gear,the fixing flange extending radially between the front fixing half-flange and the rear fixing half-flange and in that the swan neck has a C-shaped axial section whose bottom is tangent to a radial plane which is located upstream of the front fixing half-flange.

[0015] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, mounting the flange of the crown carrier between the two half-flanges of the crown provides homogeneity of stiffness on the one hand, between the half-crowns and on the other hand between the crown and the stator of the turbomachine. The stiffness is in particular optimized. Indeed, the optimized stiffness for a stator part of a turbomachine speed reducer is defined by the need for centering and limitation of misalignments due to internal meshing forces in the speed reducer and misalignments due to the turbomachine.

[0016] The operation of this type of reducer requires a stator part having an effective means of flexibility (optimized stiffness) allowing:

[0017] - limit overloads in the system due to motor movements,

[0018] - have a healthy dynamic situation of the entire reducer and turbomachine assembly,

[0019] - transmit a significant torque.

[0020] The swan neck further facilitates mounting on the crown by promoting its movement as well as the passage of the fixing members allowing the mounting and the mounting of the fixing flanges. The configuration of the swan neck also improves the manufacturability of the crown carrier. Furthermore, this arrangement is simple and does not involve substantial modifications in the speed reducer, nor at the stator level.

[0021] The speed reducer also includes one or more of the following features, taken alone or in combination:

[0022] - the swan neck has a radius of curvature which is equal to 0.5 times the height radial of the front and rear half-flanges of attachment.

[0023] - the speed reducer comprises lubricant evacuation means arranged at less in the front and rear half-flanges of attachment.

[0024] - the evacuation means comprise ejection holes which are formed in the less partly in the wall of the front and rear half-flanges and which extend radially.

[0025] - the front half-fixing flange, the rear half-fixing flange and the flange of fixing of the crown carrier respectively comprise axial fixing holes crossed by the fixing members, the axial fixing holes being arranged circumferentially around the longitudinal axis.

[0026] - the fixing members comprise axial screws or axial bolts passing through the holes.

[0027] - the crown holder comprises flexibility means such as at least one bellows.

[0028] - the crown holder comprises through openings which radially cross on either side of the wall of the crown holder.

[0029] - - the crown is connected to a casing of the turbomachine and is immobile in rotation relative to the longitudinal axis.

[0030] — the crown is connected to a shaft of the turbomachine and is movable in rotation around the longitudinal axis.

[0031] The invention also relates to an aircraft turbomachine, having a longitudinal axis and a speed reducer as mentioned above.

[0032] The invention further relates to an aircraft equipped with such a turbomachine. Brief description of the figures

[0033] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on reading the detailed explanatory description which follows, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the schematic drawings annexed documents in which:

[0034] [Fig.l] represents a mechanical reducer of a turbomachine according to the prior art;

[0035] [Fig.2] represents an example of a crown according to the prior art;

[0036] [Fig.3] represents an example of a turbomachine according to the invention;

[0037] [Fig.4] is a detailed view of an example of a speed reducer according to the invention;

[0038] [Fig. 5] is a partial axial sectional view of an embodiment of a speed reducer according to the invention; and

[0039] [Fig. 6] is a partial axial sectional view of another embodiment of a speed reducer according to the invention. Detailed description of the invention

[0040] Figures 1 and 2 represent a mechanical speed reducer intended to equip a turbomachine, in particular a crown, and which have already been described previously.

[0041] [Fig. 3] represents a turbomachine 1 with longitudinal axis X. The turbomachine 1 illustrated is a double-flow and double-spool turbomachine 1 intended to be mounted on an aircraft. Of course, the turbomachine can be a single-flow turbojet or can be a turboprop equipped with a single unducted propeller or a pair of counter-rotating, unducted propellers, known by the English expression "open rotor". The invention can be applied to other fields in which a mechanical speed reducer is used.

[0042] In the present invention, the terms "upstream" and "downstream" are defined in relation to the circulation of gases in the turbomachine and here along the longitudinal axis X and in [Fig.3] from left to right.

[0043] The turbomachine 1 comprises, in a conventional manner and, from upstream to downstream, a fan S, a low-pressure compressor 1a, a high-pressure compressor 1b, an annular combustion chamber 2, a high-pressure turbine 3a, a low-pressure turbine 3b and an exhaust nozzle 4. The high-pressure compressor 1b and the high-pressure turbine 3a are connected by a high-pressure shaft 5 and form with it a high-pressure (HP) body. The low-pressure compressor 1a and the low-pressure turbine 3b are connected by a low-pressure shaft 6 and form with it a low-pressure (LP) body.

[0044] The fan S is shrouded by a fan casing 7 which carries an external nacelle 8. The fan S generates, from an air flow F entering the fan, a primary air flow which circulates in a primary vein 9 opening into the exhaust nozzle 4 and a secondary air flow which circulates in a secondary vein 10, around the primary vein 9, opening into an ejection nozzle 11. The primary and secondary flows join and mix downstream.

[0045] The blower S is driven by a blower shaft 12 which is driven to the low pressure shaft 6 for example by means of a speed reducer 20. The latter is generally of the planetary or epicyclic type.

[0046] In the present embodiment, the turbomachine is equipped with a speed reducer 20 formed from a gear train and known by the English acronym RGB for “Reduction Gear Box”.

[0047] The reducer 20 is positioned in the upstream part of the turbomachine following the circulation of the gases of the turbomachine. A fixed structure 13 comprising schematically, here, an upstream part 13a and a downstream part 13b, composes the motor casing 16 or stator and is arranged so as to form an enclosure 14 surrounding the reducer 20. The motor casing 16 can be for example the inlet casing of the turbomachine. A lubricant mist reigns in the enclosure 14. This enclosure 14 is advantageously, but not limitingly, closed upstream by seals at the level of an upstream bearing 15 allowing the fan shaft 12 to pass through, and downstream by seals at the level of the crossing of the low pressure shaft 6.

[0048] With reference to [Fig.4], the speed reducer 20 is here of the epicyclic type. The latter comprises three components which are a sun gear 21, satellite gears 22 and a planet carrier 23 which are rotatable. The rotation speed of one of these components depends in particular on the difference in speeds of the other two components.

[0049] At the input, the reducer 20 is connected to the low-pressure shaft 6, for example by means of splines 39. The latter advantageously extend parallel to the longitudinal axis X. Thus, the low-pressure shaft 6 drives the sun gear 21 (or internal planetary gear). Conventionally, the sun gear 21, whose axis of rotation coincides with that of the longitudinal axis X of the turbomachine, drives the satellites 22, which are equally distributed over the same diameter around the longitudinal axis of rotation X. This diameter is equal to twice the operating center distance between the sun gear and the satellites. The number of satellites is generally defined between three and seven for this type of application.

[0050] Advantageously, the solar 21 is integral in rotation with the low pressure shaft 6 and the planet carrier 23 is integral in rotation with the fan shaft 12.

[0051] The set of satellites 22 is held by a frame called a planet carrier 23. Each satellite 22 rotates around its own axis. Each satellite 22 meshes with an external crown 24 (or external planetary gear).

[0052] The external crown 24 is fixed or immobile in rotation relative to the longitudinal axis X.

[0053] At the output, the set of satellites 22 drives the planet carrier 23 in rotation around the axis X of the turbomachine. The external ring 24 is fixed to a casing of the turbomachine or stator (such as the casing 16) via a ring carrier 26 described later. The planet carrier 23 is fixed and integral in rotation with the fan shaft 12.

[0054] Optionally, each satellite 22 is mounted to rotate freely using a bearing (not shown), for example of the rolling bearing or hydrodynamic bearing type. Generally, a hydrodynamic bearing is supplied with “low” pressures (usually less than 10 bars). The rotation of the bearing makes it possible to increase the pressure of the lubricant wedge and to separate the satellites and the bearings. Each bearing is mounted on one of the axes of the planet carrier 23 and all the axes are positioned relative to each other using one or more structural frames of the planet carrier 23. Each satellite 22 meshes with external teeth of the sun gear 21 and internal teeth of the external ring gear 24. The internal teeth of the external ring gear 24 may be straight (parallel to the longitudinal axis), helical or chevron-shaped.

[0055] There are a number of axes and bearings equal to the number of satellites. For reasons of operation, assembly, manufacturing, control, repair or replacement, the axes and the chassis can be separated into several parts.

[0056] For the same reasons cited above, the teeth of a reducer 20 can be separated into several helices.

[0057] Still with reference to [Fig.4], the external crown 24 is separated into two half-crowns 24a, 24b: • A front half-crown 24a consisting of a rim 24aa and a front half-flange 24ab extending radially. On the rim 24aa is the front helix of the gear teeth. This front helix meshes with that of the satellite 22 which meshes with that of the sun gear 21. • A rear half-crown 24b consisting of a rim 24ba and a rear half-flange 24bb extending radially. On the rim is the rear helix of the gear teeth. This rear helix meshes with that of the satellite 22 which meshes with that of the solar 21.

[0058] Advantageously, but not limitatively, the fixing half-flange 24ab of the front half-crown 24a and the fixing half-flange 24bb of the rear half-crown 24b form a first fixing flange 25 of the crown. The first fixing flange 25 is annular and extends radially outwards. The crown (or the two half-crowns) 24 comprises an axis of revolution which is preferably coaxial with the axis of the turbomachine. The first fixing flange 25 extends radially from a radially external surface 24c. The internal radial surface 24d radially opposed comprises propellers 32 (formed of the front and rear propellers) which mesh with the teeth of the satellites 22.

[0059] With reference to [Fig.5], a crown carrier 26 connects the external crown 24 to the stator of the turbomachine and for example to the casing 16. The crown carrier 26 makes it possible to transfer the torque from the speed reducer 20 to the stator of the turbomachine. The crown carrier 26 is advantageously, but not limited to, annular and centered on the axis of the turbomachine. For this purpose, the crown carrier 26 comprises, at a first end 26a, a second fixing flange 27. The latter extends in the present example radially inwards (towards the longitudinal axis X).

[0060] Advantageously, but not limitatively, the front fixing half-flange 24ab and the rear fixing half-flange 24bb respectively comprise orifices 31a, 31b which pass through their walls on either side and each have an axis A parallel to the longitudinal axis X. The orifices 31a, 31b are regularly spaced around the longitudinal axis X and are placed coaxially with each other. The number of orifices 31a, 31b is for example between 5 and 10.

[0061] The orifices 31a, 31b are intended to allow the passage of fixing members 40 (shown in dotted lines in [Fig.4]). In other words, the axial orifices 31a, 31b are crossed by the fixing members 40. The fixing members 40 are advantageously but not limited to threaded elements of the screw-nut type. Of course, the fixing members 40 can be any threaded element (such as axial bolts) cooperating with a clamping element or any other suitable member allowing easy assembly and disassembly without destruction of the parts equipped with them.

[0062] As shown in [Fig.5], the second fixing flange 27 extends radially between the front fixing half-flange 24ab and the rear fixing half-flange 24bb. In other words, the fixing flange 27 is sandwiched between the two fixing half-flanges 24aa, 24bb of the crown 24. Such a configuration makes it possible to avoid having a disparity in stiffness between the front and rear half-crowns.

[0063] The fixing flange 27 also comprises orifices 36 which pass through its wall on either side axially. Advantageously, but not limitingly, the orifices 36 are coaxial with the orifices 31a, 31b of the front and rear fixing half-flanges 24ab, 24bb in the installation situation. The number of orifices 36 is here identical to that of the orifices 31a, 31b.

[0064] Since the fixing flange 27 is axially arranged between the front and rear fixing half-flanges 24ab, 24bb, the fixing members 40 pass through the orifices 36. The fixing members 40 are arranged so as to clamp the half and second flanges 24ab, 24bb and the fixing flange 27.

[0065] Advantageously and with reference to [Fig.4], the fixing members 40 com take screws 41 (shown in dotted lines) which extend axially and which apply an axial force to tighten the fixing flanges. The number of fixing members 40 is identical to the number of orifices 31a, 31b, 36 respectively. The head 41a (shown in dotted lines) of the screw 41 is pressed against a downstream face of a half-flange and a nut 42 (shown in dotted lines) allowing the screw to tighten the flanges 24ab, 24bb, 27 is mounted on the threaded rod of the screw 41 on the side of the other half-flange.

[0066] In [Fig. 5], the crown carrier 26 advantageously, but not limited to, at a second end 26b, a connecting flange 43 which is intended to be fixed to a stator fixing part (such as the casing 16) of the turbomachine. In the present example, the flange 43 extends radially outwards.

[0067] The crown carrier 26 comprises a swan neck 28 which is configured so as to maintain the predetermined stiffness of the crown carrier 26 at the half-flanges and fixing flange 27. The swan neck 28 extends from one end of the fixing flange 27 of the crown carrier 26. The swan neck 28 has a C-shaped axial section whose bottom 28a is tangent to a radial plane PR which is located upstream of the front fixing half-flange 24ab. In this way, the swan neck 28 is larger than the swan necks of the prior art. Such a configuration allows the target stiffness of the crown carrier 26 to be respected with the sandwich-type assembly of the flanges 24ab, 24bb, 27. This shape also makes it easier to assemble the fixing flange 27 between the two half-flanges 24ab, 24bb of the crown 24 and also to facilitate the manufacturability of the crown carrier 26 itself.

[0068] According to an exemplary embodiment, the radius of curvature of the swan neck 28 (whose axis is perpendicular to the longitudinal axis X) is equal for example to 0.5 times the radial height (Hl) of the front and rear fixing half-flanges 24ab, 24bb and / or of the fixing flange 27.

[0069] Advantageously, the crown carrier 26 comprises flexibility means 29 which are configured so as to, on the one hand, limit overloads in the turbomachine due to the movements of certain components thereof and / or of the speed reducer 20, and on the other hand, obtain a uniform and stable distribution of the dynamic loads. In the present example, the flexibility means 29 comprise at least one bellows 30. The crown carrier 26 comprises a portion provided with several bellows 29.

[0070] Advantageously, but not limitatively, the reducer 20 comprises lubricant evacuation means 32 arranged at least in the front and rear fixing half-flanges 24ab, 24bb of the crown 24.

[0071] In the example of [Fig.6], the evacuation means 32 comprise ejection holes 33a, 33b which are formed at least in part in the wall of the front and rear half-flanges 24ab, 24bb of the crown 24. Advantageously, but not limited to tively, the ejection holes 33a, 33b extend radially. Several ejection holes 33a, 33b are distributed around the longitudinal axis X. According to the exemplary embodiment, the ejection holes open both inside the flange (at the radially internal surface 24d of the crown 24) and on the annular periphery 38 of the flange 25 (of the half-flanges 24ab, 24bb). The ejection holes can also be open on an internal face 35a, 35b of each half-flange 24ab, 24bb. The fixing flange 27 makes it possible to close, for example, the openings of the ejection holes so that the lubricant also slides on the wall of the fixing flange 27 before being evacuated from the fixing half-flanges 24ab, 24bb.

[0072] Alternatively, the ejection holes 33a, 33b are formed in the thickness of the wall of each half-flange 24ab, 24bb.

[0073] According to an embodiment not shown, the fixing flange 27 could also comprise ejection holes to allow the lubricant to be evacuated outside the speed reducer. The ejection holes of the fixing flange 27 could have the same shape as those of the half-flanges 24ab, 24bb or be formed in the thickness of the fixing flange 27. In this case, this makes it possible to increase the passage section of the lubricant in the speed reducer 20.

[0074] As shown in [Fig.6], the crown carrier 26 may comprise through openings 34 which allow the lubricant to be evacuated, the path of which is represented by the arrows L. Advantageously, the through openings 34 pass through the wall of the crown carrier 26 on either side radially. The through openings are distributed around the longitudinal axis X and preferably in a regular manner. According to an advantageous characteristic, the crown carrier may comprise several rows of through openings along the longitudinal axis X. The arrangement of these through openings 34 also makes it possible, on the one hand, to avoid lubricant retention zones in the turbomachine and, on the other hand, to obtain a weight saving. The lubricant will fall by gravity into the bellows(s) 30 and be carried along the through openings 34.

[0075] Generally, the lubricant arrives in the reducer 20 from the stator of the turbomachine in a distributor (not shown) by different means. The distributor is separated into two parts, each repeated by the same number of satellites. The reducer comprises injectors which have the function of lubricating the teeth and arms which have the function of lubricating the bearings of the satellites, these injectors and arms being connected to the distributor. The lubricant is brought towards the injector to exit through one end of the latter in order to lubricate the teeth and is also brought towards the arm so as to circulate in the different members of the reducer 20. The lubricant then exits through the ejection holes 33a, 33b which are located at the interfaces with the fixing half-flanges 24ab, 4bb, and also through the through openings 34.

[0076] Advantageously, but not limited to, the lubricant comprises oil.

Claims

Claims

1. Speed ​​reducer (20) for an aircraft turbomachine (1) having a longitudinal axis X, the speed reducer comprising a sun gear (21), planet gears (22), an external ring gear (24) and a ring gear carrier (26) fixed to the external ring gear (24), the planet gears (22) being engaged on the one hand with the sun gear (21) and on the other hand with the external ring gear (24), and the external ring gear (24) being formed of two front and rear half-ring gears (24a, 24b) which each have respectively a front fixing half-flange (24ab) and a rear fixing half-flange (24bb) extending radially outwards and which are fixed to a fixing flange (27) of the ring gear carrier (26) by fixing members (40), the ring gear carrier comprising a swan neck (28) capable of allowing the centering of the crown (24),characterized in that the fixing flange (27) extends radially between the front fixing half-flange (24ab) and the rear fixing half-flange (24bb) and in that the swan neck (28) has a C-shaped axial section whose bottom (28a) is tangent to a radial plane (PR) which is located upstream of the front fixing half-flange (24ab).,

2. Speed ​​reducer (20) according to claim 1, characterized in that the swan neck (28) has a radius of curvature which is equal to 0.5 times the radial height (Hl) of the front and rear fixing half-flanges (24ab, 24bb).

3. Speed ​​reducer (20) according to one of the preceding claims, characterized in that it comprises lubricant evacuation means (32) arranged at least in the front and rear fixing half-flanges.

4. Speed ​​reducer (20) according to claim 3, characterized in that the evacuation means (32) comprise ejection holes (33a, 33b) which are formed at least partly in the wall of the front and rear half-flanges (24ab, 24bb) and which extend radially.

5. Speed ​​reducer (20) according to one of the preceding claims, characterized in that the front fixing half-flange (24ab), the rear fixing half-flange (24bb) and the fixing flange (27) of the crown carrier (26) respectively comprise axial fixing orifices (31a, 31b, 36) crossed by the fixing members (40), the axial fixing orifices (31a, 31b, 36) being arranged circumferentially around of the longitudinal axis X.

6. Speed ​​reducer (20) according to the preceding claim, characterized in that the fixing members (40) comprise axial screws (41) or axial bolts passing through the orifices (31a, 31b, 36).

7. Speed ​​reducer (20) according to any one of the preceding claims, characterized in that the crown carrier (26) comprises flexibility means (29) such as at least one bellows (30).

8. Speed ​​reducer (20) according to any one of the preceding claims, characterized in that the crown carrier (26) comprises through openings (34) which pass radially through the wall of the crown carrier (26) on either side.

9. Turbomachine (1), in particular for aircraft, having a longitudinal axis X, and comprising a speed reducer (20) according to any one of the preceding claims.

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