Variable-pitch assembly for a turbomachine fan

Abstract

The invention relates to a variable-pitch assembly for a turbomachine fan, comprising: - a hub comprising hub mouths (16) each internally delimiting an opening (16a) that is radial relative to the longitudinal axis of rotation of the hub, - for each mouth (16): a force take-up device (24) installed through the opening (16a) and clamped against an inner surface (16b) of the mouth that is arranged parallel to a radial axis (A) of the mouth, a blade support / root (22) supporting a blade, capable of pivoting about the axis (A) and engaged in the mouth (16) via its opening (16a) inside the blade force take-up device (24), and a device (50) for locking the blade support / root inside the force take-up device.

Description

DESCRIPTION TITLE: VARIABLE TIMING ASSEMBLY FOR TURBOMACHINE BLOWER Technical field

[0001] This disclosure relates to a variable valve timing assembly for a turbomachine fan and a turbomachine fan comprising such an assembly.

[0002] The invention applies in particular to aeronautical turbomachines. Prior art

[0003] Some turbojet engines include a variable-pitch fan in which a change in the pitch or orientation of the fan blades is made in order to manage the thrust of the turbojet engine appropriately according to the phases of flight of the aircraft equipped with such a turbojet engine.

[0004] A variable-pitch fan generally comprises a hub that extends circumferentially around a longitudinal axis of rotation of the fan and the blades of the fan are mounted at the periphery of the hub. More particularly, the hub comprises a plurality of hub mouths distributed circumferentially around the periphery of the hub and which each comprise an opening oriented radially relative to the longitudinal axis. The blades are each mounted at their root in a hub mouth by means of a pivot receiving the root of the blade and equipped with ball bearings making it possible to take up all the forces to which the blade is subjected in operation.

[0005] The assembly called the bearing cartridge which is formed by the pivot of a blade and the bearings associated with the blade pivot is mounted from the inside in a mouth of the hub, while the blade is mounted on the pivot from the outside of the hub mouth. Generally speaking, the radial retention of the blades is ensured by the shape of the root of the blade and the cell which accommodates it, the pivot and its bearings, the hub in which the pivot and the external casing of the fan are integrated. The hub mouth has an internal radial stop which ensures that the pivot is maintained in its radial position when the fan is put into operation, in particular to avoid any radial displacement of the assembly (pivot and bearings), away from the longitudinal axis, under the effect of centrifugal forces due to the rotation of the fan. A mechanism internal to the hub allows each blade pivot to be pivoted on command and therefore the blade carried by the pivot.

[0006] When carrying out maintenance operations on the assembly formed by the pivot and the associated bearings (for various reasons such as, for example, following bird ingestion), the architecture presented above requires intervention from inside the hub. To do this, it is therefore necessary to dismantle the aerodynamic cone (known in English terminology as the "spinner") located upstream of the fan blades and the drainage cowl arranged internally relative to the cone, then to remove the entire internal pivoting mechanism of the blade pivots. The size of the area internal to the hub makes these dismantling operations difficult without risking damaging parts.

[0007] However, patent application FR 3 129 428 A1 discloses a variable fan timing assembly which is mounted through the radial opening of the hub mouth, from the outside of the latter, which greatly facilitates maintenance operations.

[0008] This variable fan pitch assembly comprises a blade force recovery device which is first inserted into the hub mouth to be tightened against an internal surface of the mouth, then the blade pivot is engaged inside the blade force recovery device. The blade pivot is then locked in radial position in the hub mouth from the inside of the latter. More particularly, a segment in two half-shells is provided in the lower part of the pivot to ensure the radial stop of the pivot. This segment is held in position by the blade pivot pivot control eccentric which ensures the variable pitch of the blade. This eccentric is located below the blade pivot and is therefore arranged in a position radial closer to the engine axis than the blade pivot and the hub mouth.

[0009] This variable fan timing assembly configuration makes assembly and disassembly easier as the assembly can be mounted and removed from the outside of the hub mouth.

[0010] However, to unlock the pivot during a maintenance operation, it is necessary to access the interior of the hub in order to disengage the blade pivot pivot control eccentric from its actuating rod, then remove the segment in two half-shells.

[0011] In view of the above, it would therefore be useful to remedy at least one of the drawbacks set out above. Statement of the invention

[0012] The invention thus relates to a variable timing assembly for a turbomachine fan, comprising: - a hub extending circumferentially around a longitudinal axis XX' of rotation of the hub and which comprises at least one hub mouth internally delimiting an opening oriented radially relative to the longitudinal axis, - a fan blade force recovery device which is fixed in said at least one hub opening and intended to recover the forces of a fan blade mounted in said at least one hub opening, - a fan blade support or a fan blade root which is capable of pivoting on command about a radial axis A passing through the radial opening of the hub mouth and configured to be engaged through this opening, inside the blade force recovery device, and to come into abutment along the radial axis A against an internal element of the blade force recovery device, - a device for locking by clamping the blade support or the blade root which is positioned around the latter, at a radially external position relative to a radially internal position, more close to the longitudinal axis of the internal stop element, and which is fixed to the blade force recovery device so as to grip the blade support or the blade root and to keep it in abutment along the radial axis A against the internal stop element, the blade force recovery device comprising an intermediate interface part which extends along the radial axis between a radially external position and a radially internal position and which comprises, in its radially external position, the internal stop element, the blade support or the blade root comprising, on the one hand, an elongated part which extends along the radial axis and which is arranged against at least one radial axis extension part of an internal surface of the intermediate interface part and, on the other hand, a part which extends transversely relative to the radial axis A and which is engaged against the internal stop element,the blade force recovery device comprising an assembly formed of at least a first rolling bearing in a radially external position and a second rolling bearing in a radially internal position, the first bearing comprising an internal ring which extends along the radial axis A and the second bearing comprising an internal ring which extends along the radial axis A, the intermediate interface part being sandwiched between the internal rings of the two bearings.,

[0013] The assembly defined above comprises a device for locking by clamping the blade support or the blade root which is in a position radially external to the hub mouth and the blade force recovery device, which makes it accessible from the opening of the hub mouth. It is therefore no longer necessary to have access from the inside of the hub, to unlock the blade support or the blade root, which facilitates the unlocking operations of a variable fan pitch assembly of the type described above and therefore the associated maintenance operations. The locking operation is also facilitated.

[0014] Furthermore, the architecture of the assembly defined above and in particular of the hub mouth, the blade support and the blade force recovery device is designed so that these components are mounted from the outside of the hub mouth (the blade force recovery device is first put in place in the mouth, from the outside of the mouth, before installing the blade support) and not from the inside of the mouth. This greatly facilitates subsequent work on the components constituting the assembly since it is then sufficient to remove them from the outside of the mouth without needing to access the inside of it, after having dismantled a large internal part of the fan.

[0015] According to other possible characteristics: - the hub extends circumferentially around a longitudinal axis XX' of rotation of the hub and comprises a plurality of hub mouths distributed circumferentially on an external periphery of the hub, each hub mouth internally delimiting an opening oriented radially relative to the longitudinal axis and which is capable of putting into communication a peripheral zone Ze radially external to the hub mouth, located away from the longitudinal axis, with a peripheral zone Zi radially internal to the hub mouth, which is closer to the longitudinal axis, a blade force recovery device being configured to be placed in each hub mouth through the opening of the latter, and clamped against an internal surface of the hub mouth arranged substantially parallel to a radial axis A passing through the radial opening of the hub mouth; -more particularly, the first bearing may comprise an inner ring which extends along the radial axis and comprise a first part in contact with an external surface, opposite the internal surface, of the intermediate interface part and a second part which extends away from the longitudinal axis to a radially external position relative to a radially internal position occupied by the transverse extension part of the blade support or the blade root when the latter is engaged against the internal stop element, the clamping locking device being configured to be clamped onto the second part of the inner ring so as to come, by clamping, to bear along the radial axis against the transverse extension part of the blade support or the blade root; - the inner ring of the first bearing comprises a portion extending in a radially outer position and on which the clamping locking device is clamped, the portion of the inner ring having an internal thread on an inner surface facing the blade support or the blade root, the clamping locking device comprising a two-part clamping nut arranged between the portion of the inner ring and the blade support or the blade root, which is provided with an external thread and is screwed onto the inner surface of the portion of the inner ring via the two threads; -more particularly, the tightening nut, arranged between the part of the internal ring and the blade support or the blade root, comes, at the end of screwing on the internal surface of the part of the internal ring, to bear along the radial axis against the transverse extension part of the blade support or the blade root; - the clamping locking device further comprises an anti-rotation member configured to prevent rotation between the inner ring and the clamping nut; -the two parts of the tightening nut each comprise (in particular in a zone situated at a radially external position relative to a zone situated at a radially internal position of the part concerned and which comes to bear along the radial axis against the transverse extension part of the blade support or the blade root) a plurality of teeth spaced from each other (the teeth can extend along a circumference of the tightening nut taken transversely relative to the radial axis, when the two parts are joined), the anti-rotation member being arranged between two consecutive teeth; -the clamping locking device further comprises a stop member which holds the anti-rotation member in position between two consecutive teeth while being fixed to the second part of the inner ring near its upper radial position; -the two-part clamping nut comprises elements configured to ensure the alignment in radial position of the two parts of the nut relative to each other in order to ensure the alignment of the portions of the external thread provided on both parts of the nut; -the first rolling bearing is arranged in a transverse position which is furthest from the radial axis A of the mouth and configured to take up the radial and transverse forces transmitted by the blade, the second rolling bearing being arranged in a transverse position closest to the radial axis A of the mouth and configured to take up the transverse forces transmitted by the blade; - the blade force recovery device comprises a system for holding in position and clamping by wedge effect the set of rolling bearings which is positioned at the mouth opening, in a radial position further from the longitudinal axis than the first rolling bearing; - the system for holding in position and clamping by wedge effect comprises, on the one hand, two half-shell segments having internal conical bearing surfaces cooperating with clamping parts via external conical bearing surfaces of the latter and, on the other hand, a clamping nut configured to come into contact, via external conical bearing surfaces on internal conical bearing surfaces of the clamping parts, and thus exert, on the one hand, a transverse force on the clamping parts and the two half-shell segments to place them in contact against the internal surface of the hub mouth and, on the other hand, a radial clamping force on the first rolling bearing in the direction of the longitudinal axis XX'; - the first rolling bearing comprises an outer ring arranged in an external transverse position further from the radial axis A of the mouth than the transverse position of the bearings of the first and second bearings and which, on the one hand, extends substantially parallel to the radial axis along the bearings of the first rolling bearing and the second rolling bearing and, on the other hand, bears against the second rolling bearing; - a clamping element of the second rolling bearing is arranged in an external transverse position relative to this second bearing and the external ring of the first rolling bearing bears on this clamping element; - the second rolling bearing has an inner ring arranged in an internal transverse position relative to the radial position of the bearings of the bearing, each of the internal rings of the first rolling bearing and the second rolling bearing is housed in a provision provided on a radially external surface of the intermediate interface piece; -the assembly comprises an eccentric system for controlling the pivoting of the blade support or the blade root which is configured to control the pivoting of the blade support or the blade root around the radial mouth axis, the system comprising an engagement portion configured to engage in an engagement position with a lower portion of the blade support or the blade root which is opposite an upper portion of the blade support arranged in a radially external position relative to the radially internal position of the lower portion.

[0016] The invention also relates to a turbomachine fan which comprises a variable timing assembly for a turbomachine fan as briefly described above.

[0017] According to one feature, the blower comprises a plurality of fan blades each mounted on a blade support of a mounting module of a hub mouth.

[0018] The invention also relates to a turbomachine comprising a fan as briefly described above. Brief description of the drawings

[0019] Other characteristics and advantages of the subject of the present disclosure will emerge from the following description of embodiments, given as non-limiting examples, with reference to the appended figures.

[0020] [Fig. 1] Figure 1 is a partial schematic perspective representation of a turbomachine fan according to an embodiment of one according to the invention;

[0021] [Fig. 2] Figure 2 is a partial schematic representation in axial section of the blower partially shown in Figure 1;

[0022] [Fig. 3] Figure 3 is an enlarged partial schematic representation of the hub mouth integrated fan blade mounting module of Figure 2;

[0023] [Fig. 4] Figure 4 schematically illustrates in perspective the installation, in the hub mouth, of certain components of the blade mounting module of Figure 3.

[0024] [Fig. 5A] Figure 5A is an enlarged schematic representation of a portion of Figure 4 in which the upper portion of the blade root has been intentionally omitted for clarity;

[0025] [Fig. 5B] Figure 5B illustrates a first position in the assembly of the two half-nuts of a clamping nut according to an alternative embodiment;

[0026] [Fig. 5C] Figure 5C illustrates a second position in the assembly according to the embodiment variant;

[0027] [Fig. 5D] Figure 5D illustrates a third position in the assembly according to the embodiment variant;

[0028] [Fig. 5E] Figure 5E illustrates a fourth position in the assembly according to the embodiment variant;

[0029] [Fig. 6A] Figure 6A illustrates the blade force recovery device mounted in the hub mouth;

[0030] [Fig. 6B] Figure 6B illustrates the insertion of the blade root into the interface part; [003 l][Fig. 6C] Figure 6C illustrates the end of the movement of insertion of the blade root into the interface part;

[0032] [Fig. 6D] Figure 6D illustrates the installation of the two parts of the clamping nut around the blade root;

[0033] [Fig. 6E] Figure 6E illustrates the interlocking of the two parts of the clamping nut with each other;

[0034] [Fig. 6F] Figure 6F illustrates the screwing of the two parts of the clamping nut;

[0035] [Fig. 6G] Figure 6G illustrates the placement of an anti-rotation member on the assembly of Figure 6F;

[0036] [Fig. 6H] Figure 6H illustrates the installation of a stop member on the anti-rotation member of Figure 6G. Detailed description

[0037] The invention applies to any turbomachine equipped with at least one shrouded or unshrouded fan, the fan blades of which (shrouded fan) or propeller blades of which (unshrouded fan) are equipped with a pitch or orientation change assembly, also called a variable pitch assembly. The invention can also be used for variable pitch stator blades. These may, for example, be secondary flow outlet guide vanes positioned downstream of the fan blades. They may also be flow straightening vanes in a compressor or guide vanes for the inlet flow of a compressor.

[0038] The following detailed description relates to an embodiment of a ducted fan of a turbomachine for an aircraft comprising a variable pitch fan blade assembly.

[0039] As shown in Figure 1 and generally designated by the reference numeral 10, a fan comprises a plurality of blades of which only one, numeral 12, is partially shown.

[0040] The blower 10 comprises a hub 14 extending circumferentially around a longitudinal axis of rotation XX' of the hub and comprises a plurality of hub vents 16 distributed circumferentially on an outer periphery of the hub.

[0041] Each hub mouth 16 internally delimits an opening 16a oriented radially, along an axis A having a radial orientation relative to the longitudinal axis X-X'. The hub mouths 16 are thus all oriented in the manner of a star relative to the hub, each along a radial axis A. The radial opening 16a has a passage section which extends perpendicular to the radial axis A and is capable of putting into communication a peripheral zone Ze radially external to the hub mouth 16, located away from the longitudinal axis X-X', with a radially internal peripheral zone Zi of the hub mouth, which is closer to the longitudinal axis than the zone Ze. In other words, the hub mouth 16 has an opening 16a passing through along the radial axis.

[0042] As shown in Figure 1, the hub 14 comprises in its central internal part, from the center towards the outside, a control means comprising here a fixed piston 39 of a control cylinder and the movable chamber 40 of the latter, as well as a connecting piece 41 between this control cylinder and connecting rods 42 illustrated in Figure 2 and described below.

[0043] As shown in Figure 1, a blade 12 is shown mounted in a hub mouth 16. The other mouths are shown empty to avoid complicating the drawing but a blade is normally also mounted in each of them.

[0044] Figure 2 shows, in axial section along the axis X-X', a part of the fan which comprises a hub mouth 16 in which is integrated a module for mounting a fan blade 12. This module is part of a variable-pitch assembly of the fan blades according to an embodiment of the invention which comprises the hub 14 and other modules for the other blades of the fan.

[0045] The fan blade mounting module comprises a blade force absorption device 24 which is intended to be in direct contact with a blade root 22. Alternatively, the blade force absorption device 24 may be in contact with a blade support or pivot intended to support a blade root (in particular for mounting with a bulb blade root). In the latter case, the fan blade mounting module also comprises the blade support or pivot. The blade support comprises an upper part in which a cell is arranged which has the function of receiving the blade root and its fixing bulb. The upper part of the blade support generally forms a plate which surmounts a lower central stud of substantially cylindrical shape.

[0046] In the following description, the blade force recovery device 24 will be in direct contact with a blade root 22 and is configured to be placed in the hub mouth 16 through the radial opening 16a of the latter, from a peripheral zone Ze radially external to the mouth (figures 1 and 2). These configurations of blade mounting module (blade force recovery device 24) and hub mouth allow the module to be placed from the outside of the hub, which simplifies maintenance operations when it comes to removing the module from the vent (from outside this vent) to access the internal components of the module. Similarly, the repositioning of the inspected module 34, and possibly repaired or replaced, is carried out from outside the hub 14. It is therefore no longer necessary to dismantle the entire internal cowling of the fan and the internal mechanisms for controlling the pivoting of the blades. Considerable time is thus saved and maintenance costs are greatly reduced. The risks of damage to the surrounding structures in place in the fan are also reduced. Mounting / dismounting from above (in Figure 2) also makes it possible to free up space under the module 34, for example, to accommodate other parts.

[0047] More particularly, the retention of the fan blade 12 in a fixed radial position is ensured by maintaining the blade root 22 in the locked position in the blade force recovery device 24 (as described later). Furthermore, the blade root is guided by the blade force recovery device 24 for setting the blade pitch. The blade pitch setting is defined as corresponding to an angular orientation of the blade relative to the radial axis A passing through the hub mouth.

[0048] The blade root 22 is in particular capable of pivoting around the radial axis A of the hub mouth 16 under the action of a mechanism which will be described later and which interacts with a lower (radially internal) part 22a of the blade root 22 opening along the radial axis A beyond the blade force recovery device 24, in a radially internal zone of the hub. The lower part 22a is opposite an upper part 22b of the blade root 22 which is closer to the radial opening 16a of the hub mouth.

[0049] As more particularly shown in FIG. 2, an eccentric system or mechanism for controlling the pivoting of the blade root 22 is provided inside the hub 14, under the mouth 16 (for example in a radially internal position, close to the axis X-X') and is configured to control the pivoting of the blade root 22 around the radial axis A of the mouth and therefore its angular orientation.

[0050] More particularly, the eccentric blade root pivot control system is configured to engage with the lower emerging or projecting portion 22a of the blade root in order to pivot the latter and therefore the blade that it supports, on command, according to the desired pivot angle relative to the flight phase considered.

[0051] The pivot control system comprises, for example, the axial control cylinder centered on the longitudinal axis XX' and described with reference to FIG. 1. This cylinder comprises the axial rod 39 fixed relative to the structures of the turbojet (fig. 1) and the movable body or chamber 40. The pivot control system also comprises a connecting part 41, called a synchronization ring, on which several connecting rods 42 are connected by one of their two opposite ends. A connecting rod is generally provided per blade support and per mouth and is arranged in a radially internal position relative to the mouth. The other end of each connecting rod is connected to one end 44a of a part forming an eccentric 44, here in the general shape of an elbow (however the shape of the part may vary), the opposite end 44b of which is mounted integral with the lower part 22a of the blade root 22.The end 44b is arranged around the lower projecting part 22a and forms an engagement end or part which is engaged with the lower projecting part 22a (in FIG. 3 the part 44 has been deliberately simplified compared to the configuration of FIG. 2). More particularly, the internal part of the engagement end or part 44b is for example provided with internal grooves which engage by meshing with the recesses between the complementary shaped grooves of the external surface of the lower part 22a of the blade support 22 (in the manner of a gear), in an engagement position, to transmit the rotational movement communicated by the eccentric-forming part 44.The axial displacement of the movable body 40 drives the connecting part 41 in translation, and therefore the axial translation of the connecting rods 42, which causes the part 44 to pivot and thus correspondingly modifies the angular orientation of the blade support and therefore of the blade.

[0052] The blade force recovery device 24, for its part, forms a unitary block which is mounted in one piece, before the blade root 22, at the interior of the hub mouth 16 passing through the radial opening 16a, from a peripheral zone Ze external to the mouth.

[0053] The blade force recovery device 24 is put in place by being clamped against an internal surface 16b of the hub mouth 16 (fig. 3), a surface which is substantially arranged in a transverse position distant relative to the radial axis A (a transverse direction extending perpendicular to the radial axis). More particularly, the internal surface 16b extends substantially parallel to the radial axis A over a first portion 16bl from the opening 16a, then forms a second convergent portion 16b2 (here in the manner of a funnel with a neck of generally frustoconical shape followed by an end portion substantially parallel to the axis A) narrowing the internal space at the mouth away from the opening 16a (in the direction of the axis X-X'). This narrowing forms a stop along the radial axis A for the module (device 24), in the direction of the interior of the hub (in the direction of the axis XX 7 ).

[0054] The device 24 comprises an assembly formed of at least two ball bearings: - an outer bearing 26 (first bearing) arranged, relative to the radial axis A, in a transverse position which is furthest from this axis, and -an inner bearing 28 (second bearing) arranged in a transverse position which is closest to the radial axis A relative to the external transverse position of the outer bearing 26. It will be noted that the notion of exterior and interior of the bearings also refers directly to the position of each of these bearings relative to the longitudinal central axis XX' insofar as the outer bearing 26 is located in a radially external position relative to the radially internal position of the inner bearing 28.

[0055] The outer bearing 26 is configured to take up the radial forces (along the radial axis A) and transverse forces (along a transverse axis perpendicular to the radial axis A) transmitted by the blade during operation of the fan (rotation around the axis XX 7 ) and is arranged in a radial position (along the radial axis A) which is further from the longitudinal axis XX' than the radial position of the bearing inner bearing 28. The inner bearing 28 is configured to take up the transverse or tangential forces transmitted by the blade during operation of the fan, while the outer bearing 26 is of larger dimensions than the inner bearing 28 insofar as it is configured to take up radial forces along the radial axis A (forces due to centrifugal force) which are the greatest forces to which the device 24 is subjected during rotation of the blade. It will be noted that the devices 24 are mounted radially in a star shape relative to the hub 14 in such a way that the orientation of each device 24 in space varies according to the angular position of the hub mouth considered.

[0056] As more particularly shown in FIG. 3, the outer bearing 26 comprises an outer ring 26a, an inner ring 26b and ball bearings 26c jointly gripped by the two rings.

[0057] Similarly, the inner bearing 28 comprises an outer ring 28a, an inner ring 28b and ball bearings 28c jointly gripped by the two rings.

[0058] The outer ring 26a of the outer bearing 26 is arranged in an external transverse position which is further from the radial axis A of the mouth than the transverse position of the bearings 26c and 28c of the outer 26 and inner 28 bearings. The outer ring 26a extends substantially parallel to the radial axis A along the bearings 26c of the outer bearing and downwards along the outer ring 28a of the inner bearing 28, and bears against this outer ring 28a. It will be noted that the outer ring 26a extends downwards (towards the inner bearing) following the profile of the internal surface 16b of the mouth with which it is in contact, that is to say by first adopting a substantially rectilinear portion 26a 1, then by tightening so as to adopt a convergent portion 26a2 (neck forming a frustoconical portion followed by a rectilinear portion).A clamping element 32 of the inner bearing 28 may be disposed in an outer transverse position relative to the inner bearing 28 and the tightened lower portion 26a2 of the outer ring 26a of the outer bearing 26. rests on this clamping element. This clamping element ensures a preload or pre-stress of the inner bearing 28.

[0059] This clamping element 32 is for example a clamping nut screwed onto the inside of the outer ring 26a of the outer bearing 26. For example, a key 34e and a circlip 34f make it possible to ensure that the clamping element 32 does not loosen (from above, i.e. at the level of the mouth opening 16a), as described later, (although other members ensuring that the element 32 does not loosen can alternatively be envisaged.

[0060] The device 24 also comprises an intermediate interface part 30 arranged between, on the one hand, the outer 26 and inner 28 bearings (the part 30 is sandwiched between the two bearings 26, 28) and, on the other hand, the blade root 22 and extends along the radial axis between a radially outer position and a radially inner position. The part 30 is part of the block 24 and serves as a mechanical interface with the blade root 22. Such an interface makes it possible to avoid wearing the bearing rings if they were in direct contact with the blade root 22.In the device 24 described above, the inner bearing 28 is housed in the outer ring of the outer bearing 26, as well as the intermediate interface piece 30 which makes it possible to connect the inner rings 26b and 28b together and to provide support for the blade root 22, thus making it possible to form a "cartridge" containing the rolling bearings and the intermediate interface piece 30 and which can be handled in a single unitary block (in one piece) by an operator wishing either to install the device 34 in a hub mouth (from the outside of the hub), or to remove it (still from the outside).

[0061] The inner ring 26b, 28b of each of the outer and inner bearings is arranged in an internal transverse position relative to the external transverse position of the bearings 26c, 28c of each bearing which is further from the radial axis A than that of the inner rings. Each inner ring is housed in an arrangement 30a, 30b provided on an external surface of the intermediate interface part 30. More particularly, the part 30 comprises, on its external surface oriented in the direction of the bearings 26c, 28c of each bearing, an external peripheral collar 30c which delimits at- above and below it (in Figure 3) an upper space and a lower space for receiving respectively the internal rings 26b and 28b. The interface part 30 is pierced in its central part to receive axially (along the radial axis A) the blade root 22 which comprises an elongated part extending along the radial axis and comprises an internal stop element 30d acting as an axial stop along the radial axis for the blade root 22. The blade root 22 comprises, on its external surface intended to come into contact with the blade force recovery device, and in particular with an internal surface of the interface part, an engagement part 22c (e.g. external shoulder) of complementary shape bearing on the internal axial stop element 30d. As shown in Figure 3, the internal axial stop element 30d is formed by the upper end (radially external position) of the interface part 30 which here forms an annular rim.In order to cooperate with this internal axial stop element, the external shoulder 22c of the blade root 22 which extends transversely relative to the general elongated shape of the blade root can take the form of an annular collar.

[0062] The blade force recovery device 24 may also comprise a system 34 for holding in position and clamping by wedge effect the assembly of rolling bearings 26, 28 inside the hub mouth 16.

[0063] This system 34 is for example positioned substantially at the level of the mouth opening 16a (after placing the device 24 in the mouth), in a radial position (along the radial axis A) which is further from the longitudinal axis XX' (radially external position) than the external bearing 26 (radially internal position). In Figure 3, the system 34 is arranged above the bearing 26.

[0064] The system 34 for holding in position and clamping by wedge effect is, for example, a keystone type system which clamps the bearing cartridge against the internal surface 16b of the mouth. Such a system 34 comprises, for example, two segments in two half-shells 34a-b, clamping parts 34c (distributed circumferentially and internally to the segments), a clamping nut 34d, as well as an anti-rotation key 34e and a circlip 34f. The segments 34a-b and the clamping parts 34c ensure that the bearing cartridge is held in the radial position (along the radial axis A) and clamped against the inner surface 16b of the hub mouth (along a transverse direction relative to the radial axis A and away from it). The segments 34a-b and the outer part of the clamping parts 34c with which the segments cooperate are in particular housed in an annular groove 16c arranged in the thickness of the wall of the hub mouth. The clamping nut 34d, the anti-rotation key 34e and the circlip 34f thus ensure that the segments 34a-b and clamping parts 34c are held in the radial position.More particularly, the two segments 34a-b and the clamping parts 34c have respective facing conical surfaces (the internal conical surface portions, for the segments, and the external conical surface portions facing, for the clamping parts, are each oriented on a cone whose apex is positioned on the axis A away from the central axis X-X', i.e. the cone is open in the direction of the central axis X-X') which are held in abutment against each other thanks to the clamping force induced by the nut 34d on the clamping parts 34c (the nut has an internal conical surface portion which bears on each of the internal conical surface portions of the clamping parts, the conical surface portions being each oriented on a cone whose apex is positioned on the axis A in the direction of the central axis X-X', i.e. the cone is open away from the axis central X- X').It should be noted that other types of mounting can perform the same function.

[0065] In order to ensure the locking of the blade root in the blade force recovery device 24, a device 50 for locking by clamping the blade root 22 is placed in a radially external zone of the device 24, substantially at the level of the radial mouth opening 16a.

[0066] The device 50 for locking by clamping the blade root 22 is positioned around the latter, in a radially external position relative to the radially internal relative position of the internal stop element 30d of the interface part 30. This device 50 is fixed to the blade force recovery device 24 so as to grip the root blade and to hold it in axial abutment against the internal abutment element 30d.

[0067] Figure 4 is an enlarged and partial view showing, in a half-section in perspective, the interior of the hub mouth on which the front part of the rolling bearings has been removed in order to make visible the intermediate part 30 and the components of the locking device 50. Figure 5A, for its part, is a view similar to that of Figure 4 but with the blade root 22 truncated in its upper part.

[0068] As shown in Figure 3 and more particularly in Figures 4 and 5A, the inner ring 26b of the outer bearing 26 extends along the radial axis A and comprises, on the one hand, a first part 26bl in contact with an outer surface, opposite the inner surface, of the intermediate interface part 30 and, on the other hand, a second part 26b2 which extends away from the longitudinal axis XX' to a radially outer position relative to a radially inner position occupied by the transverse extension part or shoulder 22c of the blade root when the latter is engaged against the inner axial stop element 30d. It will be noted that the radially external position of the second part 26b2 is arranged substantially at the level of the opening 16a of the hub mouth and therefore beyond the set of rolling bearings (the second part 26b2 axially extends the internal ring in the direction of the opening 16a).

[0069] More particularly, the clamping locking device 50 is configured to be clamped onto the second part 26b2 so as to come, by clamping, into abutment along the radial axis against the transverse extension part or shoulder 22c of the blade root.

[0070] In this embodiment, the second part 26b2 has an internal thread F1 on an internal surface of the internal ring which is oriented opposite the blade root 22 (the internal ring surrounds the blade root). The clamping locking device 50 comprises, for its part, a clamping nut 52 in two parts 52a, 52b arranged between the second part 26b2 and the blade root 22 in FIGS. 3 and 4 when it is in place. The clamping nut 52 is provided with an external thread F2 which is screwed onto the internal surface of the second part 26b2 by means of the two complementary threads F1 and F2, so that the tightening nut 52 comes, at the end of screwing onto the internal surface of the second part 26b2, to bear along the radial axis against the transverse extension part or shoulder 22c of the blade root 22. More particularly, as shown in FIGS. 3 and 4, the tightening nut 52 comes, at the end of screwing, to bear against an upper face (radially external) of the shoulder 22c, opposite the lower face (radially internal) of this shoulder which bears on the internal stop element 30d.

[0071] As shown in Figures 4 and 5A, the part 52a (resp. 52b) of the clamping nut 52 comprises a plurality of teeth 52a 1 (resp. 52b 1) spaced from each other and which extend along a half-circumference of the clamping nut taken transversely with respect to the radial axis A, when the two parts 52a, 52b are joined together. The teeth 52a 1 (resp. 52bl) are more particularly arranged in a portion 52ae (resp. 52be) of the part 52a (resp. 52b) which is located at a radially external position (upper portion in FIGS. 4 and 5A) relative to a portion 52ai (resp. 52bi) of this part 52a (resp. 52b) which is located at a radially internal position (lower portion in FIGS. 4 and 5A) and which comes to bear, along the radial axis A, against the transverse extension part or shoulder 22c of the blade root 22. The radially internal portion 52ai (resp. 52bi) of the part 52a (resp.52b) of the tightening nut 52 comes, more particularly, to bear against the upper face (radially external) of the shoulder 22c. The radially internal portion 52ai (resp. 52bi) of the part 52a (resp. 52b) has a part of the external thread F2 of the nut 52. The teeth of the nut 52 thus form, as shown in FIGS. 4 and 5A, a crenellated upper free edge.

[0072] Each part 52a, 52b thus carries a part of the teeth of the tightening nut 52 and forms a half-nut which here resembles a half-cylinder cut along its axis of revolution. It will be noted, however, that the tightening nut can take other forms, in particular the two constituent parts of this nut can adopt forms different ones which do not necessarily each resemble a half-cylinder.

[0073] According to a variant illustrated in Figures 5B to 5E, the clamping nut is formed of two half-nuts E1 and E2 which are different from two half-cylinders. The first (resp. second) half-nut E1 (resp. E2) comprises a central part E1.1 (resp. E2.1) of cylindrical internal shape provided with an internal half-thread F1.1 (resp. F1.2). The first (resp. second) half-nut E1 (resp. E2) comprises two arms E1.2, E1.3 (resp. E2.2, E2.3) which extend from the central part E1.1 (resp. E2.1) and which are each located in a different transverse plane, taken relative to the axis of revolution al (resp. a2) of the cylindrical internal shape of the central part E1.1 (resp. E2.1). The two half-nuts E1 and E2 have identical configurations which, when the two half-nuts face each other, allow the two arms of one half-nut to fit together with the two arms of the other half-nut, as shown in the various figures 5B-5E. Thus, the arm E2.3 is housed under the arm El.3 and the arm El.2 is housed under the arm E2.2, thus allowing the two half-nuts El and E2 to fit together to form the clamping nut of Figure 5E in which the two internal half-threads Fl.1 Fl.2 are joined to form the complete internal thread. However, the use of this variant of clamping nut in the mode of Figures 4 and 5A requires modifying its external surface so that it has an external thread similar to the internal thread F2 described above. In addition, teeth are also provided in the upper part of the nut to fulfill the function described in relation to the mode of Figures 4 and 5A. This variant provides a large contact surface between the two half-nuts.

[0074] The clamping locking device 50 further comprises an anti-rotation member 54, such as an anti-rotation key, configured to prevent rotation between the inner ring 26b and the clamping nut 52, more particularly one of the two parts of the nut. In this example, the anti-rotation member 54 is in particular arranged between two consecutive teeth, for example two teeth 52a 1 of the part 52a.

[0075] As shown more particularly in FIG. 5A, the anti-rotation member 54 takes the form of an annular ring 54a provided with a finger 54b arranged transversely with respect to the radial axis A. The finger 54b extends internally and externally in a direction transverse with respect to the circumference of the annular ring 54a so as to be able to be inserted both between two consecutive teeth of the nut 52 and in an opening O made in the second part 26b2 of the internal ring.

[0076] It will be noted that, according to a variant not shown, the teeth and the anti-rotation member can be replaced by any other mechanical structure ensuring the same function of relative locking in rotation between the internal ring and the blade root.

[0077] Furthermore, the clamping locking device 50 may further comprise a stop member 56 which holds the anti-rotation member 54 in position between two consecutive teeth, while being fixed to the second part 26b2 of the inner ring 26b near its upper radial position. This stop member 56 takes for example here the form of a stop ring or circlip which extends above the anti-rotation key, against the annular ring 54a of the latter, while being partially inserted inside a groove G provided in the internal surface of the second part 26b2, near the upper end (radially external) of this second part, substantially at the level of the radial opening 16a of the mouth.

[0078] Furthermore, the two-part clamping nut 52a, 52b comprises alignment elements 52a2, 52b2, such as hooks, configured to ensure the radial positional alignment of the two parts 52a, 52b of the nut relative to each other in order to ensure the alignment of the two portions of the external thread F2 provided on the two parts of the nut.

[0079] In Figure 5A, the hooks 52a2, 52b2 are formed in part by portions of teeth 52a1 of the part 52a and portions of teeth 52bl of the other part 52b each configured to fit into each other at the two diametrically opposite junction zones of the two parts 52a, 52b in a circumferential direction. More particularly, a portion 52b2 of tooth of a part 52b is inserted under a portion 52a2 of tooth of a part 52a and, in a diametrically opposite manner, a portion 52a2 of tooth of the part 52a is inserted under a portion 52b2 of tooth of part 52b as shown in Figure 5A. Such an arrangement thus makes it possible to fix the radial position of each of the two parts of the clamping nut relative to each other, which makes it possible to align the two external thread portions of the external thread F2 with each other. It will be noted that other means of aligning the external thread portions of the two parts of the clamping nut can be envisaged such as for example a mortise-and-tenon type fitting at the level of the two diametrically opposite zones of the two parts of the clamping nut in contact with each other, in the zones of these parts which are located below the teeth.

[0080] When placing the blade mounting module in the hub mouth 16, the device 24 (roller bearing cartridge) is first introduced through the radial opening 16a into the hub mouth 16 so as to be positioned in abutment against the internal surface 16b of the mouth. The system 34 described above is placed from above, component element by component element, starting with the segments 34a-b which are inserted into the annular groove 16c internal to the mouth, for example near its opening 16a, the clamping parts 34c which come internally to bear along a conical bearing surface against the conical internal faces of the segments, then the clamping nut 34d, the anti-rotation key 34e and the circlip 34f. The device 24 is thus clamped against the internal surface 16b of the mouth, in a transverse direction perpendicular to the axis A.

[0081] Generally, the blade root 22 is then introduced inside the mouth from above (from outside the mouth) and is more particularly inserted by force inside the interface part 30 to arrive at the installed position of figures 3 and 4. As shown in these figures, the blade root 22 is stopped in translation, in a first direction (here downward), by the internal element forming a stop 30d of the interface part 30.

[0082] Figures 6A-H illustrate more particularly the schematic diagram of the assembly of the blade root 22 and the locking device 50 of this last with respect to the blade force recovery device 24 previously installed in the mouth 16a of hub 16.

[0083] Figure 6A shows the blade force recovery device mounted inside the mouth 16a of the hub 16, waiting to receive the blade root 22 (or the blade support according to another embodiment already explained above).

[0084] Figure 6B shows the blading of which only the blade root 22 appears above the radial mouth opening 16a. The blade root 22 is arranged concentrically with the interface part 30 and the blade root is inserted axially (along the radial axis A) inside the interface part 30 (downward movement in the figure) until the shoulder 22c of the blade root 22 comes to bear (axial stop) against the peripheral rim 30d (internal stop element) of the interface part 30 (figure 6C).

[0085] As shown in Figure 6D, the two parts or half-nuts 52a and 52b of the tightening nut 52 are positioned around the blade root 22 (around a cylindrical portion of the root), above the second part 26b2 of the inner ring 26b, so as to grip the blade root.

[0086] As shown in Figure 6E, the hooks of the two parts 52a and 52b of the clamping nut 52 described in relation to Figure 5A are brought into interlocking contact with each other in order to obtain the radial alignment of the two parts (and therefore of the two external thread portions forming the external thread F2) illustrated in the enlarged view of Figure 5A.

[0087] In Figure 6F the two parts 52a, 52b of the clamping nut are screwed onto the second part 26b2 of the inner ring by means of the respective corresponding external threads F2 and internal threads F1 until the desired tightening torque is reached (end of screwing). During this operation it is also ensured that one of the spaces or notches between two consecutive teeth of the clamping nut 52 is positioned opposite the opening O made in the second part 26b2 of the inner ring.

[0088] Figure 6G is a partial enlarged view of the variable valve timing assembly of Figure 6F and shows the placement of the member anti-rotation 54, with the annular ring 54a positioned between the second part 26b2 and the teeth of the clamping nut and the locking finger 54b inserted into the space or notch between two consecutive teeth which has been previously positioned opposite the opening O, as described above in relation to figure 6F.

[0089] Then, as shown in Figure 6H, the stop member 56 (e.g., circlip) is put in place so as to cover the anti-rotation member 54 by fixing itself to the second part 26b2 of the inner ring in order to lock the assembly and secure it to the ring 26 and therefore to the blade force recovery device 24. More particularly, the stop member 56 is partially inserted into the internal groove G of the second part 26b2 and bears along the radial axis A on the anti-rotation member 54, thus pressing the latter against the tightening nut 52.

[0090] Thanks to this assembly and this locking system, the blade root 22 is thus retained axially (along the axis A) in a second opposite direction (here ascending) inside the blade force recovery device in the hub mouth.

[0091] Once the blade root 22 is locked in the device 24 (“bearing cartridge”) as explained above with reference to FIGS. 6A-H, the engagement portion 44b of the eccentric system is engaged with the lower emerging or projecting portion 22a of the blade root 22. In the present example, the internal splines of the engagement portion 44b are inserted between the external splines of the lower portion 22a to obtain an engagement position (meshed position) which will subsequently make it possible to control the pivoting of the blade root desired for a predetermined blade setting.

[0092] It will be noted that to carry out a maintenance operation on the variable-pitch assembly described above, in particular on a blade, it is sufficient to unlock the blade root relative to the blade force recovery device 24 by carrying out, on the locking device 50, the reverse operations to that described with reference to FIGS. 6A-F. To remove the blade root 22 from the device 24 and therefore from the hub mouth 16, it is not necessary to access the interior of the hub as in the prior art since it is sufficient to axially remove the blade root 22 upwards (to move from the position of Figure 6C to that of Figure 6B) in order to disengage the lower part 22a from the engagement part 44b of the eccentric system.

[0093] The blade root locking device 50 in the blade force recovery device 24 as described above may take other forms than those illustrated and described and may in particular be applied to a blade force recovery device of different structure. The blade force recovery device to which the blade root locking device may be applied generally has an intermediate / internal interface part between the blade force recovery device and the blade root, as well as an external ring concentric with this intermediate interface part and on which the locking device may be fixed.

[0094] Furthermore, the fan comprises, in a known manner, in its upstream part (on the left in FIG. 2), an aerodynamic cone 46 ("spinner" in English terminology) forming a cover enveloping in particular the fan blade mounting modules and the blade support pivoting control mechanism. The fan also comprises, inside the cone 46, an internal cover 48. In a known manner, the fan blades extend radially beyond the cone 46 in order to be exposed to the flow air stream surrounding the cone.

[0095] Although the present description refers to specific exemplary embodiments, modifications may be made to these examples without departing from the general scope of the invention as defined by the claims. Furthermore, individual features of the various embodiments illustrated or mentioned may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

CLAIMS

1. Variable timing assembly for a turbomachine fan, comprising: - a hub (14) extending circumferentially around a longitudinal axis (X-X') of rotation of the hub and which comprises at least one hub mouth (16) internally delimiting an opening (16a) oriented radially relative to the longitudinal axis, - a fan blade force recovery device (24) which is fixed in said at least one hub opening (16) and intended to recover the forces of a fan blade mounted in said at least one hub opening (16), -a fan blade support or a fan blade root (22) which is capable of pivoting on command about a radial axis (A) passing through the radial opening (16a) of the hub mouth (16) and configured to be engaged through this opening (16a), inside the blade force recovery device (24), and to come into abutment along the radial axis (A) against an internal element (30d) of the blade force recovery device (24), -a device (50) for locking by clamping the blade support or the blade root (22) which is positioned around the latter, at a radially external position relative to a radially internal position, closer to the longitudinal axis, of the internal stop element (30d), and which is fixed to the blade force recovery device (24) so as to grip the blade support or the blade root (22) and to keep it in abutment along the radial axis (A) against the internal stop element (30d), the blade force recovery device (24) comprising an intermediate interface part (30) which extends along the radial axis (A) between a radially external position and a radially internal position and which comprises, at its radially external position, the internal stop element (30d), the blade support (22) or the blade root comprising, on the one hand,an elongated portion which extends along the radial axis (A) and which is arranged against at least one radial axis extension portion of an internal surface of the intermediate interface part (30) and, on the other hand, a portion (22c) which extends transversely relative to the radial axis (A) and which is engaged against the internal stop element (30d), the blade force recovery device (24) comprising a, assembly formed of at least a first rolling bearing (26) in a radially external position and a second rolling bearing (28) in a radially internal position, the first bearing (26) comprising an internal ring (26b) which extends along the radial axis (A) and the second bearing (28) comprising an internal ring (28b) which extends along the radial axis (A), the intermediate interface piece (30) being sandwiched between the internal rings (26b, 28b) of the two bearings (26, 28).

2. Assembly according to claim 1, characterized in that the hub (14) extends circumferentially around a longitudinal axis (X-X') of rotation of the hub and comprises a plurality of hub mouths (16) distributed circumferentially on an external periphery of the hub, each hub mouth (16) internally delimiting an opening (16a) oriented radially relative to the longitudinal axis and which is capable of putting into communication a peripheral zone (Ze) radially external to the hub mouth, located away from the longitudinal axis, with a peripheral zone (Zi) radially internal to the hub mouth, which is closer to the longitudinal axis, a blade force recovery device (24) being configured to be placed in each hub mouth (16) through the opening (16a) of the latter,and clamped against an inner surface (16b) of the hub mouth arranged substantially parallel to a radial axis (A) passing through the radial opening (16a) of the hub mouth.,

3. An assembly according to claim 1, characterized in that the inner ring (26b) of the first bearing (26) comprises a portion (26b2) extending in a radially outer position and onto which the clamping locking device (50) is clamped, the portion (26b2) of the inner ring (26b) having an internal thread (F1) on an inner surface facing the blade support (22) or the blade root, the clamping locking device (50) comprising a clamping nut (52) in two parts (52a, 52b) arranged between the portion (26b2) of the inner ring (26b) and the blade support (22) or the blade root, which is provided with an external thread (F2) and is screwed onto the inner surface of the portion (26b2) of the inner ring (26b) via the two threads.

4. Assembly according to claim 3, characterized in that the clamping locking device (50) further comprises an anti- rotation (54) configured to prevent rotation between the inner ring (26b) and the clamping nut (52).

5. Assembly according to claim 4, characterized in that the two parts (52a, 52b) of the tightening nut each comprise a plurality of teeth (52al, 52bl) spaced from each other, the anti-rotation member (54) being arranged between two consecutive teeth.

6. Assembly according to one of claims 3 to 5, characterized in that the two-part clamping nut (52) comprises elements (52a2, 52b2) configured to ensure the alignment in radial position of the two parts (52a, 52b) of the nut relative to each other in order to ensure the alignment of the portions of the external thread (F2) provided on the two parts of the nut.

7. Assembly according to one of claims 1, 3 to 6, characterized in that the blade force recovery device (24) comprises a system (34) for holding in position and clamping by wedge effect the assembly of rolling bearings which is positioned at the mouth opening (16a), in a radial position further from the longitudinal axis than the first rolling bearing (26).

8. Assembly according to one of claims 1, 3 to 7, characterized in that a clamping element (32) of the second rolling bearing (28) is arranged in an external transverse position relative to this second bearing and the external ring (26a) of the first rolling bearing (26) bears on this clamping element.

9. Assembly according to one of the preceding claims, characterized in that it comprises an eccentric system (44) for controlling the pivoting of the blade support or the blade root (22) which is configured to control the pivoting of the blade support or the blade root around the radial axis (A) of the mouth, the system (44) comprising an engagement part (44b) configured to engage in an engagement position with a lower part (22a) of the blade support or the blade root which is opposite an upper part (22b) of the blade support arranged in a radially external position relative to the radially internal position of the lower part.

10. Turbomachine fan (10), characterized in that it comprises a variable-pitch assembly for a turbomachine fan according to one of the preceding claims.

11. A turbomachine comprising a fan according to claim 10.

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