Assembly comprising a pivoting support sleeve and a ring for a variable pitch blade root, turbine engine provided with such assembly, and

Abstract

The invention relates to an assembly for a turbine engine, in particular of an aircraft, comprising a ring (2) having an axis of rotation (O). According to the invention, the assembly comprises a plurality of support sleeves (12), each support sleeve having an axis of rotation (D) and each support sleeve being configured to receive a stud (8) of a variable pitch vane (3), each support sleeve (12) comprising a bore (30) passing through both sides of the support sleeve (12) along the axis of rotation (D), each support sleeve (12) is mounted to pivot on the ring (2) about a pivot axis (C, C ') transverse to the radial axis (Z) and the axis of rotation (O).

Description

Technical Field

[0001] The invention relates to the general field of aviation. In particular, the invention is intended to integrate variable pitch blades into a ring that is assembled to an aircraft turbine engine. The invention also relates to a corresponding turbine engine and a corresponding disassembly method. Background Art

[0002] Variable pitch blades can equip the unducted propeller of a turboprop engine or the ducted fan of a turbojet engine. By changing the pitch of the blades around their axis, the performance of the turbine engine can be improved while limiting the weight of the propulsion assembly. Variable pitch blades make it possible to change the flow through the variable pitch blades according to the operating conditions of the turbine engine and the flight phase of the aircraft to brake the aircraft (reverse thrust) and / or restore the pumping margin on a turbine engine with a very high bypass ratio. Documents US-A-4047840, US-B2-8075270 and US-A1-2016146025 describe examples of variable pitch blades.

[0003] The variable pitch blades are usually held in the rotating hub by means of a pivot connection. The pivot connection is made by a stud of the variable pitch blade, which is housed in a housing in the hub. This type of connection makes it possible to take into account the ratio between the aerodynamic moment at the stud and the centrifugal force, which ratio may not be sufficient to ensure that the stud is correctly positioned on the hub.

[0004] Figure 1 An example of a stud for a variable pitch blade is shown. A cylindrical stud 1A is mounted in a housing 2A of a ring 3A in a rotating manner around a pitch axis A. The ring 3A is attached to a rotor shaft 4A via a trunnion 5A and is centered on the longitudinal axis X of the turbine engine. The stud 1A rotates through two rolling bearings 6A stacked along the pitch axis A. The bearings 6A each include an inner ring 7A fixed to the stud 1A and an outer ring 8A fixed to the ring 3A. The radially outer end 9A of the stud is configured to be connected to the inner end of the blade extending radially outward, and the radially inner end 10A of the stud is connected to the pitch change system 11A. However, this configuration means that it is difficult to disassemble the stud of the variable pitch blade after damage. When the outer ring of the bearing is attached to the ring, the entire module (including the ring and the blade) must be removed for maintenance. When the blade is surrounded by a casing, it is more necessary to disassemble the assembly. This prolongs the intervention time and causes economic losses. Summary of the invention

[0005] The object of the present invention is to provide a solution making it possible to facilitate the assembly and disassembly of variable pitch blades having a cylindrical root, in particular in the event of damage, while avoiding affecting the mass of the module comprising the blade.

[0006] According to the invention, this object is achieved by an assembly for a turbine engine, in particular a turbine engine of an aircraft, comprising a ring having an axis of rotation, the assembly comprising a plurality of support sleeves, each having an axis of rotation and each configured to accommodate a stud of a variable pitch blade, each support sleeve comprising a bore passing through both sides of the support sleeve along the axis of rotation, each support sleeve being mounted to pivot on the ring about a pivot axis transverse to the radial axis and to the axis of rotation.

[0007] Thus, the solution enables the above-mentioned objectives to be achieved. In particular, this configuration enables each variable pitch blade to be removed individually when damaged and / or in need of inspection. Thus, it is no longer necessary to disassemble the assembly of the hub with a plurality of variable pitch blades. Furthermore, this saves time during maintenance, so that, for example, the turbine engine is not fixed to the ground, which in turn saves money. In addition to this, repairing the variable pitch blades individually helps to reduce the impact on the environment by avoiding destruction of the assembly.

[0008] The assembly also includes one or more of the following features, taken alone or in combination:

[0009] Each support sleeve is pivotable between a first position, in which the axis of rotation of the support sleeve is parallel to the radial axis and perpendicular to the axis of rotation, and a second position, in which the axis of rotation of the support sleeve is transverse to the radial axis.

[0010] - the ring is equipped with a plurality of orifices passing through its annular wall along a radial axis and regularly arranged around the axis of rotation, and wherein the ring comprises two ears protruding on either side of each orifice, each supporting sleeve being mounted between two ears and pivoting on an ear along a pivot axis.

[0011] The ring extends along its axis of rotation between an upstream end and a downstream end, the ring comprising two ears protruding near the upstream end, on which ears each supporting sleeve pivots along a pivot axis.

[0012] The ring comprises mechanical reinforcement means comprising ribs extending along the axis of rotation between the upstream and downstream ends of the ring on the one hand and along the radial axis on the other hand, the ribs being arranged around the axis of rotation on either side of the orifice.

[0013] The assembly comprises a plurality of variable pitch blades, each of which is equipped with a cylindrical stud, each stud being mounted so as to pivot about a pitch axis in a borehole of a support sleeve.

[0014] - Each variable pitch blade comprises a blade extending from a stud, the blade and the stud being formed as a single piece.

[0015] Each stud comprises an attachment at the radially outer end, the attachment being configured to house the blade root and comprising a groove extending along an axis perpendicular to the axis of the stud.

[0016] The assembly comprises attachment means configured to retain the support sleeve on the ring when the ring is in the first position.

[0017] The ring is equipped with a plurality of orifices which pass through the annular wall of the ring along a radial axis and are regularly arranged around the axis of rotation.

[0018] - The stud of each vane is configured to pass through an aperture.

[0019] - Each supporting sleeve faces an orifice in a first position.

[0020] - Each supporting sleeve at least partially passes through the aperture in the second position.

[0021] - Each supporting sleeve is located outside the orifice and spaced apart from the orifice in the second position.

[0022] The assembly comprises at least two rolling bearings, each comprising an inner ring mounted on the outer wall of the stud and an outer ring configured to bear against the cylindrical inner wall of the bore of the support sleeve, the inner and outer rings defining a raceway for rolling elements.

[0023] The invention also relates to a turbine engine comprising such an assembly, a pitch change system connected to the radially inner end of the stud of each variable pitch blade, and a rotor shaft connected to the ring.

[0024] The invention also relates to an aircraft comprising a turbine engine as described above.

[0025] Finally, the invention relates to a method for disassembling an assembly as described above, comprising the following steps:

[0026] - removing the attachment means for attaching the support sleeve to the ring,

[0027] - pivoting the support sleeve upstream along the pivot axis and along the axis of rotation, and

[0028] - Remove the stud from the support sleeve or the support sleeve from the ring.

[0029] According to the method, before the step of extracting the stud, the method comprises a step of disengaging the support sleeve relative to the ring at the pivot axis.

[0030] Another feature of the method is that it comprises a step for tilting the support sleeve relative to the ring after the detaching step. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The invention will be better understood and other objects, details, features and advantages of the invention will become more apparent on reading the following detailed description of embodiments of the invention given by way of purely illustrative and non-limiting example, with reference to the schematic drawings, in which:

[0032] Figure 1 is an axial cross-sectional view of an example of a cylindrical root according to the prior art;

[0033] Figure 2 is a perspective view of a hub portion of a variable pitch blade guided by a housing according to the present invention;

[0034] Figure 3 is a perspective view of a ring configured to carry a plurality of variable pitch blades according to the present invention;

[0035] Figure 4 is a detailed view of an example of a ring configured to carry variable pitch blades according to the present invention;

[0036] Figure 5 An embodiment of a support sleeve and a ring for supporting a variable pitch blade according to the present invention is shown;

[0037] Figure 6 According to the present invention Figure 4 A radial cross-sectional view of the ring and the support sleeve;

[0038] Figure 7 Another embodiment of a support sleeve and a ring for supporting a variable pitch blade according to the present invention is shown;

[0039] Figure 8 is a detailed perspective view of a support sleeve configured to carry a variable pitch blade and located in a first position according to the present invention;

[0040] Fig. 9 is a detailed perspective view of a support sleeve configured to carry a variable pitch blade and located in a second position according to the present invention;

[0041] Fig.10 Another embodiment of a blade and a support sleeve according to the present invention is shown;

[0042] Fig.11 The steps for disengaging the support sleeve in the disassembly method according to the present invention are shown;

[0043] Fig.12 The tilting step for supporting the sleeve in the disassembly method according to the present invention is shown;

[0044] Fig.13shows a tilting step in a disassembly method according to the present invention; and

[0045] Fig.14 The steps for removing and separating the support sleeve installed on the blade in the disassembly method according to the present invention are shown. DETAILED DESCRIPTION

[0046] Figure 1 A cylindrical stud as already described is shown for a variable pitch blade mounted in a rotating ring of a turbine engine. Figure 1 The technology prior to the present invention is shown.

[0047] The invention is applicable to variable pitch blades and to all turbine engines equipped with these variable pitch blades, the variation or pivoting of which is controlled by a pitch variation system 40 .

[0048] The turbine engine may be a turboprop engine including a plurality of unducted variable pitch blades, known as an "open rotor engine", or a turbojet engine including a plurality of ducted variable pitch blades, known as a "turbofan engine". The turbine engine is configured to be mounted on an aircraft. Of course, variable pitch blades may also be used on other machines such as wind turbines.

[0049] Figure 2 A turbine engine 1 configured to equip an aircraft is shown. The turbine engine generally comprises, from upstream to downstream, along the gas flow and along the longitudinal axis X, a compressor assembly E1, an annular combustion chamber E2 and a turbine assembly E3. These assemblies form a gas generator G. The compressor and turbine assemblies respectively comprise at least one compressor stage and at least one turbine stage. In the case of a turbojet engine, the turbojet engine comprises a fan S comprising variable pitch blades and arranged upstream of the compressor assembly E1. In a turboprop engine, one or more counter-rotating propellers comprising variable pitch blades are positioned upstream of the compressor assembly (tractor configuration) or downstream of the turbine assembly (pusher configuration).

[0050] exist Figure 2 , the module of the turbine engine 1 is centered on a longitudinal axis X, the module of the turbine engine 1 comprising a ring 2 carrying a plurality of variable pitch blades 3. The module is located upstream of a gas generator G, the rotor of which drives the plurality of variable pitch blades about the longitudinal axis X. The variable pitch blades 3 may have an inclination relative to the pitch axis A of the blades 3, which inclination varies according to the engine speed reached, in order to improve the aerodynamic performance and the efficiency of the turbine engine equipped with variable pitch blades.

[0051] Advantageously, but not limitingly, the turbine engine module 1 comprises a casing 4 centered on the longitudinal axis X and surrounding the variable pitch blade 3. The casing 4 comprises a cylindrical wall 4a having an inner surface 5 on which an abrasion-resistant annular coating 6 is arranged. The abrasion-resistant annular coating 6 is positioned opposite the free end 7 of the blade 3 and at a short distance from the free end 7 of the blade 3. This short distance means that when the blade 3 rotates, the abrasion-resistant coating 6 can be worn by friction with the blade 3, thereby limiting gas leakage at the free end 7.

[0052] Each variable pitch blade 3 comprises a stud 8 and a blade 9 extending outwardly from the stud 8 along a radial axis Z. The radial axis Z is perpendicular to the longitudinal axis X. Each blade 9 comprises a leading edge 10a and a trailing edge 10b connected by a pressure side surface 11a and a suction side surface 11b.

[0053] refer to Figure 3 and Figure 4 , the stud 8 of each variable pitch blade 3 is carried by the ring 2 via a support sleeve 12. The support sleeve 12 is removable, and the support sleeve 12 is also mounted so that the support sleeve 12 can be moved along the pivot axis relative to the ring 2. In particular, each stud 8 is mounted so that each stud 8 can pivot around its pitch axis A in the corresponding support sleeve 12, and the pivoting of each support sleeve 12 makes it easier to access the variable pitch blade 3 on the one hand and to remove the variable pitch blade 3 from the ring 2 on the other hand.

[0054] The ring 2 has an axis of rotation O which, in the installed condition, is centered on the longitudinal axis X of the turbine engine. Figure 3 In the embodiment shown, the ring has a substantially frustoconical annular wall 15. Alternatively, the annular wall 15 of the ring 2 has a cylindrical shape with a straight circular cross section.

[0055] Advantageously, the ring 2 is mounted so that it can rotate about the longitudinal axis X. To this end, the ring 2 extends between an upstream end 13a and a downstream end 13b along the axis of rotation of the ring 2. The upstream end 13a is attached to a trunnion (not shown) which in turn is attached to the rotor shaft (not shown).

[0056] Advantageously, the frustoconical wall 15 of small diameter is located towards the upstream end 13a and the frustoconical wall 15 of large diameter is located towards the downstream end 13b. This enables better integration of the ring 2 into a turbine engine.

[0057] The ring 2 comprises a plurality of orifices 14 passing through an annular wall 15 of the ring 2 on both sides along a radial axis. The orifices 14 are evenly spaced around the longitudinal axis X.

[0058] Advantageously but not limitingly, each orifice 14 has a generally rectangular shape with an annular or circular portion. More specifically, each orifice 14 has four portions of large radius connected to four portions of small radius (large radius greater than small radius).

[0059] The ring 2 is equipped with mechanical reinforcement means configured to increase the mechanical strength of the ring 2. The mechanical reinforcement means comprise a plurality of ribs 16 extending along the radial axis Z and the longitudinal axis. Figure 4 In the example shown, each rib 16 extends between an annular flange 17 and the upstream end 13a. The annular flange 17 also provides mechanical reinforcement for the ring 2. Alternatively, the ribs 16 also extend inwardly from the annular wall. In this case, the inner ring will be mounted inside the ring 2, wherein a portion of the inner ribs connects the wall of the ring.

[0060] Advantageously, but not limitingly, the annular flange 17 is centred on the axis of rotation O and extends along a radial axis. The annular flange 17 is also situated upstream of the downstream end 13 b of the ring 2 .

[0061] Still reference Figure 4 , we see that the ring 2 comprises a reinforcing structure 18 which is annular and centred on the longitudinal axis X. This reinforcing structure 18 comprises a U-shaped radial cross section, the two branches of which are connected to the wall 15 of the ring 2 . The orifice of the U-shaped section faces the inside of the ring 2 . This reinforcing structure forms part of the mechanical reinforcement of the ring 2 .

[0062] In this way, each orifice 14 is surrounded by ribs 16, annular flanges 17 and reinforcement structures 18, the ribs 16 facing each other in the circumferential direction around the longitudinal axis. The flanges, ribs and reinforcement structures form a box to reinforce the wall of the ring 2. The ribs 16 are arranged in an axisymmetric manner (or regularly around the axis of the turbine engine) to maintain sufficient rigidity during operation of the turbine engine. When the variable pitch blade 3 pivots around its pitch axis A, the tangential forces pass through the ribs 16.

[0063] refer to Figure 3 , Figure 5 and Figure 6 , each support sleeve 12 is configured to accommodate a stud 8 of a variable pitch blade. Each support sleeve 12 comprises a cylindrical body 21 having an axis of rotation D. In the mounted condition, the axis of rotation is coaxial with the pitch axis A of each variable pitch blade 3. Each support sleeve 12 is pivotally mounted on the ring 2 about a pivot axis C between a first position, in which the axis of rotation D of the support sleeve is parallel to the radial axis Z, and a second position, in which the axis of rotation D of the support sleeve 12 is transverse to the radial axis Z.

[0064] In the example of this embodiment, the pivot axis C is transverse to the rotation axis D. Advantageously, the pivot axis C is also transverse to the pitch axis A of each variable pitch blade 3. To this end, the ring 2 comprises two ears 19 facing each other in the circumferential direction. The ears 19 protrude substantially along the radial axis (inclined by plus or minus 10°). In particular, the ears 19 are located on both sides of each orifice 14 in the ring 2 in the circumferential direction. Each ear 19 comprises a bore 20 which passes through the wall of the bore 20 on both sides along an axis transverse to the radial axis Z. The bore 20 in the ear defines the pivot axis C of the support sleeve 12. In this example, the ear 19 is made in one piece with the wall 15 of the ring 2.

[0065] exist Figure 5 and Figure 6 In the embodiment shown, the support sleeve 12 comprises two protrusions 25 (at Figure 3 As can be seen in the figure, two protrusions 25 extend radially relative to the cylindrical outer wall 22a of the support sleeve 12. The protrusions 25 have coaxial axes. Each protrusion 25 is configured to engage in a corresponding bore 20 in a pivotally connected manner so that the support sleeve 12 can pivot about the pivot axis C. The axis of the protrusion 25 is defined in the middle plane of the support sleeve 12, which is perpendicular to the pitch axis. When it is necessary to remove the pitch blades 3, each support sleeve 12 can be pivoted or tilted back and forth along the pivot axis C. In order to remove the variable pitch blades, the support sleeve 12 is pivoted upstream.

[0066] Advantageously, but not limitingly, the support sleeve 12 is manipulated manually by an operator.

[0067] Each aperture 14 is large enough to allow the passage of a stud 8 and a portion of a pitch system that can be activated from the inside. These same apertures 14 are large enough to allow the support sleeve 12 and the blade 9 to pivot upstream. Advantageously, whatever the position of the support sleeve 12, the support sleeve 12 is at least partially arranged above the corresponding aperture 14 along the axis of the aperture (substantially coaxial with the radial axis). Alternatively, a portion of the body of the sleeve 12 may extend in the first position or in the second position, in the corresponding aperture 14.

[0068] An advantageous feature is that the size of each aperture 14 is greater than the diameter (defined by the cylindrical outer wall 22 a ) of the support sleeve 12 . The circumference of each aperture 14 is, for example, 5 times the diameter of the support sleeve 12 .

[0069] like Figure 5As shown, the attachment device is configured to hold the support sleeve 12 on the ring 2 and prevent the support sleeve 12 from pivoting during operation. The attachment is located downstream of the ring 2. More specifically, the attachment can be made by a threaded connection or a bayonet connection. Advantageously, the attachment device is located at two points downstream to ensure that the support sleeve 12 and the variable pitch blade are correctly positioned and retained on the ring 2. In the example shown, the attachment device includes two through-hole portions 23 arranged in the wall 15 of the ring 2. The hole portion 23 passes through the wall 15 along the radial axis. The support sleeve 12 includes two bases 24 protruding and extending from the cylindrical outer wall 22a of the support sleeve 12. These bases and hole portions are configured to be passed by screws, studs or threaded rods, and the screws, studs or threaded rods are configured to cooperate with nuts to, for example, tighten the assembly.

[0070] From above and reference Figure 6 As can be seen, each support sleeve 12 comprises a bore 30 which passes through the support sleeve 12 on both sides along its axis of rotation D. The bore 30 forms a housing for a stud 8 of the blade 3. The stud 8 of each blade 3 is pivotally mounted in the bore 30 along the pitch axis A. The stud 8 is mounted in the support sleeve 12 and the support sleeve 12 is mounted on the ring 2 so that the blade 3 is prevented from detaching during the rotation of the ring 2 about the longitudinal axis. Each stud 8 extends along the pitch axis A. Advantageously, the stud 8 has a cylindrical shape. Advantageously, but not restrictively, the stud 8 is a straight cylindrical shape. The expression "straight cylindrical shape" refers to a shape obtained by moving a generating line along a directional curve, the directional curve being defined in a plane perpendicular to the generating line. The curve may be circular.

[0071] Each stud 8 comprises a radially outer end 31 (relative to the pitch axis A) connected to the blade 9. Figure 3 , Figure 5 and Figure 6 In the embodiment shown, the radially outer end 31 is fixed to the blade 9, which is not shown in these figures. In other words, the stud 8 and the blade 9 are formed as a single piece (integral).

[0072] Each stud 8 includes a radial inner end 32 opposite to the radial outer end 31. The stud 8 includes a hole 34 opening at the radial inner end 32. Advantageously, the hole 34 leads to the cavity through an opening 35. The hole 34 is centered on the pitch axis A. In this example, the hole 34 is configured to accommodate a pitch transfer insert (not shown), which is configured to transfer torsional torque to the stud 8 to change the pitch of the blade 3. The transfer insert is connected to the pitch change system 40 and is attached to the stud 8 by an attachment device. The attachment device includes, for example, a screw centered on the longitudinal axis (through the opening 35) and a nut tightened on the screw. Of course, other attachment devices such as threaded attachments can also be used.

[0073] In order to arrange the blade 3 around its pitch axis A, each stud 8 is pivotally mounted by means of at least two rolling bearings 36, 37. The bearings 36, 37 are stacked along the pitch axis A. More specifically, each bearing 36, 37 comprises an inner ring and an outer ring, the inner ring being fixed to the outer wall 8a of the stud and the outer ring being fixed to the cylindrical inner wall 22b of the support sleeve 12. The cylindrical inner wall 22b is radially opposite to the cylindrical outer wall 22a. The inner ring and the outer ring define a raceway for rolling members. The rolling members include balls or rollers. The bearings 36, 37 can be used to absorb centrifugal forces (along the pitch axis A) and / or lateral forces (in a plane perpendicular to the pitch axis A). Alternatively, the rolling members can also be balls. Retaining means are provided to retain the bearings 36, 37 in the holes 30 and on the roots, and a locking system is provided to retain these retaining means in place.

[0074] The bearings 36, 37 and the stud 8 form a pivot for each variable pitch blade.

[0075] Figures 7 to 9 Another embodiment of a support sleeve 12 and a ring 2 for a variable pitch blade is shown. In this example, the radially outer end 31 of the stud 8 includes an attachment 33 configured to accommodate a blade root 9 (not shown). The blade 3 (formed as a single piece with its root) and the stud 8 are formed by two separate parts. In this example, the attachment 33 includes a groove 38 extending along an axis perpendicular to the axis of the stud 8. Advantageously, but not restrictively, the groove 38 has a spherical cross-section. The groove 38 is open upstream and downstream of the attachment 33 so that the root of the variable pitch blade can be inserted into the groove 38 from upstream to slide in the groove 38.

[0076] This embodiment and Figures 3 to 6 The embodiment shown differs in the position of the pivot axis C'. The pivot axis C' is located upstream of the ring 2. More precisely, the pivot axis is defined by the bores 20' of two ears 19' which protrude substantially radially from the wall 15 of the ring and in the vicinity of the upstream end 13a. Here, the protrusions are arranged on the reinforcing structure 18. The support sleeve 12 comprises a bridge 39 extending radially from the cylindrical outer wall 22a of the support sleeve 12. At the free end of the bridge 39, the bridge 39 comprises bores 42 extending transversely on both sides (at Fig.11 In the mounted state, the axis of the bore 42 of the bridge 39 is coaxial with the axis of the bore 20' of the ear 19'. A transverse shaft (not shown) is provided to pass through the bores 20', 42 of the ear and the free end. This configuration facilitates disassembly. In this way, the support sleeve 12 can be pivoted between a first position, in which the pitch axis is coaxial with the radial axis (see Figure 8), in the second position, the pitch axis is transverse to the radial axis (see Fig. 9 ). In the first position, the support sleeve 12 is inside at least a portion of the orifice 14 , while in the second position, the support sleeve 12 is outside the orifice 14 and upstream of the ring 2 .

[0077] In an alternative embodiment, the free end of the bridge 39 comprises transversely extending pins (not shown), each of which is configured to engage in a bore 20 ′ in the ear 19 ′ to pivot a corresponding support sleeve.

[0078] This embodiment differs in the arrangement of the attachment means. Figure 8 and Fig. 9 It is shown that the axis of the attachment device extends along the longitudinal axis. In particular, the attachment device comprises two through-hole portions 23' which pass through the radial flange 17 on both sides along the longitudinal axis. The support sleeve 12 comprises two bases 24' protruding from the cylindrical outer wall 22a of the support sleeve 12. These bases and the hole portions are configured to be passed through by screws, studs or threaded rods which are configured to cooperate with nuts, for example to tighten the assembly.

[0079] If only the blades need to be repaired and / or inspected, each blade can be disassembled individually by removing the root of the blade from the stud held in the support sleeve 12. Of course, in the event of damage to the stud 8, it is possible to remove the stud 8 from the support sleeve 12 by disengaging the transverse shaft from the ear. Prior to this, the attachment means are also disassembled to enable pivoting.

[0080] The following are variations of the previous embodiments, such as Fig.10 In this variant, the stud 8 and the blade 9 are formed as one piece (integral). The blade 9 extends radially from the stud 8. The stud 8 is inserted into a support means 12 which is connected to the ring 2 by attachment means (screws and nuts or threaded elements) similar to the above embodiments.

[0081] An example of a method for mounting the bucket studs on the ring 2 will now be described.

[0082] The method comprises a step of assembling the stud 8 and the support sleeve 12. To this end, the inner rings of the two bearings are mounted on the stud 8 (for example by shrink fitting). The outer ring of the rolling bearing that is outermost relative to the axis of the stud 8 is mounted so as to be supported laterally in the bore 30 of the support sleeve 12. The outer ring of this rolling bearing is, for example, shrunk onto the cylindrical inner wall 22b of the support sleeve 12. The rolling element is then mounted on the outer ring.

[0083] The method comprises a step of inserting the stud 8 into the support sleeve 12. During this insertion, the stud 8 is inserted into the corresponding bore 30 along the axis of the support sleeve 12.

[0084] The method then comprises the steps of mounting the rolling element of the other innermost bearing and then mounting the outer ring of the rolling element. The respective outer rings of the two rolling bearings are locked by tightening the retaining device. An anti-rotation system is also assembled to prevent the retaining device from moving. Another device for retaining the outer ring of the second bearing and the anti-rotation system of the device are also assembled.

[0085] Of course, the outer ring may be pre-mounted in the bore 30 and the inner ring may then be mounted on the stud 8. Similarly, the rolling elements of the innermost bearing may be assembled first and then the rolling elements of the outermost bearing.

[0086] The method comprises assembling the support sleeve 12 onto the ring 2. Figures 3 to 6 In the embodiment shown, the protrusion 25 is arranged to correspond to the bore 20 in the ear 19. The protrusion 25 is inserted into the bore to create the pivot. Figures 7 to 10 In the embodiment shown, the bores 42 in the free ends of the bridges 39 are arranged to correspond to the bores 20' in the ears 19', and a transverse shaft is then inserted through the bores for each support sleeve 12 to enable each support sleeve to pivot. Figures 7 to 10 In another embodiment shown, projections are inserted into the bores of the ears 19 , 19 ′, so that the support sleeve 12 can be pivoted relative to the ring 2 .

[0087] The method then comprises a step of releasably attaching the support sleeve 12 to the ring 2. Advantageously, a threaded element is inserted into the bore and then a fastening element is mounted on the threaded element to hold the support sleeve 12 on the ring 2, in particular during commissioning of the turbine engine and during operation of the turbine engine. During this step, the support sleeve 12 is in a first position and at least partially inside the orifice 14. Each stud 8 passes through a corresponding orifice 14 in the ring 2. Similarly, in the mounted condition, the radially inner end of the stud 8 is located inside the ring 2, facing the axis of rotation of the ring 2 and the longitudinal axis X of the turbine engine. In the first position, the axis of rotation D of the support sleeve 12 is parallel to the radial axis.

[0088] When the stud 8 is equipped with the attachment 33 , the root of the blade is inserted into the groove 38 before the support sleeve 12 is attached to the ring 2 .

[0089] Once the support sleeve 12 is attached, each blade is connected to the pitch changing system 40. To this end, the pitch transmitting insert is inserted into the hole 34 in the stud 8 and then attached to the stud 8. The pitch transmitting insert is then attached to the pitch changing system 40 by suitable means to produce the rotation of the variable pitch blade about the pitch axis A.

[0090] The assembly is disassembled by performing the above steps in reverse. In particular, the disassembly method consists in removing the attachment means for attaching the support sleeve 12 to the ring 2. In this example, all that is done is to loosen the screws and nuts on the first attachment member 45. The support sleeve 12 is tilted upstream to enable easy access to the stud 8. After tilting, the support sleeve 12 is in the second position and outside the orifice 14, upstream of the ring 2.

[0091] The disassembly method then consists in extracting the stud 8 from the support sleeve 12 with the variable pitch blade.

[0092] exist Fig. 9 In the case of the embodiment shown, the method may comprise a step of removing the blade from the attachment 33 before the pivoting step or even the step of removing the attachment means. Of course, after pivoting of the support sleeve 12, the blade and the blade root may be removed from the attachment.

[0093] exist Fig.10 In the case of the embodiment shown (blade and stud in one piece), the method comprises a step of disengaging the support sleeve 12 from the ring 2 at the pivot axis C. This disengagement step is performed by translating the support sleeve 12 upstream along the arrow 43, as Fig.11 To do this, the transverse shaft is first removed from the bores of the ear 19 and of the bridge 39, or the projection is removed from the bore of the ear 19'. This disengagement step is followed by tilting the support sleeve 12 upstream (generally rotating around an axis transverse to the axis of the orifice 14), as shown Fig.12 and Fig.13 shown. Fig.14 The support sleeve 12 and the bucket (studs 8 and blades) are shown now separated from the ring 12 for inspection or possible repair. The studs can also be separated from the support sleeve.

Claims

1. An assembly for a turbine engine, in particular an aircraft turbine engine, comprising a ring (2) having an axis of rotation (O), characterized in that The assembly comprises a plurality of support sleeves (12), each having an axis of rotation (D) and each configured to receive a stud (8) of a variable pitch blade (3), each support sleeve (12) comprising a bore (30) passing through both sides of the support sleeve (12) along the axis of rotation (D), each support sleeve (12) being mounted to pivot on the ring (2) about a pivot axis (C, C') transverse to the radial axis (Z) and the axis of rotation (O).

2. Assembly according to the preceding claim, characterized in that Each support sleeve (12) pivots between a first position, in which the rotation axis (D) of the support sleeve (12) is parallel to the radial axis and perpendicular to the rotation axis (O), and a second position, in which the rotation axis (D) of the support sleeve (12) is transverse to the radial axis (Z).

3. Assembly according to any one of the preceding claims, characterized in that The ring (2) is provided with a plurality of orifices (14) passing through an annular wall (15) of the ring (2) along the radial axis (Z) and regularly arranged around the axis of rotation (O), and the ring (2) comprises two ears (19) projecting on either side of each orifice (14), each supporting sleeve (12) being mounted between the two ears (19) and pivoting on the ears (19) along the pivot axis (C).

4. The assembly according to claim 1 or 2, characterized in that The ring (2) extends along the axis of rotation (O) of the ring (2) between an upstream end (13a) and a downstream end (13b), the ring (2) comprising two ears (19') protruding near the upstream end (13), each supporting sleeve (12) pivoting on the ears (19') along the pivot axis (C').

5. Assembly according to any one of the preceding claims, characterized in that The ring (2) comprises mechanical reinforcement means, comprising ribs (16) extending, on the one hand, along the axis of rotation (O) between the upstream end (13a) and the downstream end (13b) of the ring, and, on the other hand, along the radial axis (Z), the ribs (16) being arranged around the axis of rotation O on both sides of the orifice (14).

6. Assembly according to any one of the preceding claims, characterized in that The assembly comprises a plurality of variable pitch blades (3), each of which is equipped with a cylindrical stud (8), each stud (8) being mounted to pivot about a pitch axis (A) in the bore (30) of the support sleeve (12).

7. Assembly according to the preceding claim, characterized in that Each variable pitch blade (3) comprises a blade (9) extending from the stud (8), the blade (9) and the stud (8) being formed as a single piece.

8. The assembly according to claim 6, characterized in that Each stud (8) comprises an attachment (33) at a radially outer end (31) configured to receive a blade root (3) and comprising a groove (38) extending along an axis perpendicular to the axis of the stud (8).

9. The assembly according to any one of claims 2 to 8, characterized in that The assembly comprises attachment means (23; 23') configured to retain the support sleeve (12) on the ring 2 when the ring is in the first position.

10. Assembly according to any one of claims 2 and 3 to 9, characterized in that Each support sleeve (12) faces the orifice (14) in the first position and at least partially passes through the orifice (14) in the second position.

11. An assembly according to any one of claims 2 and 3 to 9, characterized in that Each support sleeve (12) is located outside the aperture and spaced apart from the aperture in the second position.

12. Assembly according to any one of the preceding claims, characterized in that The assembly comprises at least two rolling bearings (36, 37), each rolling bearing comprising an inner ring and an outer ring, the inner ring being mounted on the outer wall of the stud (8), the outer ring being configured to bear against the cylindrical inner wall (22b) of the bore of the support sleeve (12), the inner ring and the outer ring defining a raceway for rolling elements.

13. A turbine engine (1) comprising an assembly according to any one of the preceding claims, a pitch change system (40) connected to the radially inner end (32) of the stud (8) of each variable pitch blade (3), and a rotor shaft connected to the ring (2).

14. A method for disassembling an assembly according to any one of claims 1 to 12, the method comprising the steps of: - removing the attachment means for attaching the support sleeve (12) to the ring (2), - pivoting the support sleeve (12) upstream along the pivot axis (C, C') and along the axis of rotation (O), and - Remove the stud (8) from the supporting sleeve (12).

15. Method for disassembling an assembly according to the preceding claim, characterized in that Prior to the step of extracting the stud, the method comprises a step of disengaging the support sleeve (12) relative to the ring (2) at the pivot axis (C).

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