Variable-pitch blade for an aircraft turbine engine

Abstract

The invention relates to a variable-pitch blade (214) for an aircraft turbine engine, this blade (214) comprising: - a fibrous structure (221) comprising a blade (229) connected to a root (223), the root comprising a tubular attachment portion (225) centred on a pitch axis (A), - a tubular metal sleeve (215) mounted around the attachment portion (225), and - an eccentric (278) fitted and secured to the root (223) of the fibrous structure, this eccentric (278) comprising a first annular part (278a) centred on the pitch axis (A) and coupled to the sleeve (215) by a first coupling connection (C1), and a second part (278b) connected to the first part (278a) and defining a hinge axis (B), the hinge axis being at a distance from the pitch axis (A).

Description

[0001] DESCRIPTION

[0002] TITLE: VARIABLE PITCHING TURBOMACHINE FOR AN AIRCRAFT

[0003] Technical field of the invention

[0004] The present invention relates to a variable pitch blade for an aircraft turbomachine, and in particular for an aircraft turbomachine pusher propeller.

[0005] Technical background

[0006] The state of the art includes in particular documents FR-A1-3017 163, FRAI -3080322, FR-A1-3 098789, W0-A1 -2022 / 018353, W0-A1-2022 / 018355, US-A1 -2015330233, FR-A1 -3138806 and W0-A1-2024 / 033590.

[0007] An aircraft turbomachine propeller can be enclosed or unenclosed, as is the case with an open-rotor design, for example. A propeller comprises blades that may have variable pitch. The turbomachine then includes a mechanism that allows the blade pitch angle to be modified in order to adapt the thrust generated by the propeller according to the different phases of flight.

[0008] The design of a propeller blade involves several disciplines whose objectives are generally conflicting. It must allow for optimal aerodynamic performance (i.e., provide thrust while maximizing efficiency), guarantee the blade's mechanical strength (i.e., withstand the mechanical stresses resulting from static and dynamic loads), while limiting mass and acoustic signature. In particular, improving the propeller's aerodynamic performance tends towards an increase in the Bypass Patio (BPR), which translates into an increase in its external diameter and therefore the blade span. However, increasing the BPR goes hand in hand with reducing the Fan Pressure Patio (FPF). Consequently, a variable-pitch system (variable-pitch blade) is generally required for the propeller to be operable across its entire flight envelope.

[0009] There are several technologies for attaching a variable pitch propeller blade and several technologies for controlling the angular pitch of such a propeller blade.

[0010] A propeller generally comprises a hub that carries blade retention systems and guides for the angular pitch of its blades. The hub has a general annular or polygonal shape around a first axis, which is the longitudinal axis of the turbomachine, and includes openings distributed around this first axis in which the blade roots and the aforementioned systems are housed.

[0011] Each of these orifices has a substantially radial orientation with respect to the first axis and receives bearings for guiding the foot of a blade around a second radial axis with respect to the first axis, and which is an axis for setting the corresponding blade.

[0012] Each propeller blade comprises a blade connected to a foot. The foot of each blade is mounted in one of the hub's bores and in the bearings of that bore, and is held in place by a retaining system. Each foot is also associated with an eccentric that connects the blade to the mechanism that actuations its angular pitch.

[0013] In current technology, the eccentric can be formed as a single piece with the blade foot. However, this solution is not always feasible. The hub holes designed to receive the blade feet are radially through-holes to allow the propeller, and in particular the guide bearings, to be mounted according to a specific kinematic pattern. According to this pattern, the foot of each blade is engaged in the corresponding hub hole by translation along the blade's alignment axis, radially from the outside to the inside relative to the first axis. The blade foot is then connected to the actuation mechanism located inside the hub. Forming the eccentric as a single piece with the blade foot can make this mounting impossible and is therefore not always feasible for this reason.Forming the eccentric in one piece with the blade root is not always feasible, particularly when the distance between the pivot axis and the alignment axis is significant. Another solution is to attach and fix the eccentric to the root. In this case, the eccentric is generally coupled to the root by a linkage that transmits the rotational torque necessary for blade alignment.

[0014] The eccentric then comprises a first part that is coupled to the foot and a second part that is connected to the first part and defines a pivot axis parallel to and at a distance from the alignment axis. The actuation mechanism is articulated to this second part of the eccentric at this pivot axis, generally by a ball joint.

[0015] Furthermore, a variable-pitch blade can advantageously be made of composite material. Patent documents W0-A1-2022 / 018353 and W0-A1-2022 / 208002 describe, for example, the addition of reinforcing and structural elements at the base of a blade.

[0016] One of the challenges to overcome concerns the absorption of the torsional moment around the blade's pitch axis. Aerodynamic and centrifugal forces acting on the blade generate a resulting torsional moment that must be absorbed to control the blade pitch via the actuation mechanism. This torque is generally absorbed by the resin of the composite base, which connects the blade components.

[0017] The invention offers an improvement to the solutions of the prior art which allows to transmit a rotational torque in an optimized manner to a blade made of composite material.

[0018] Summary of the invention: According to a first aspect, the invention relates to a variable-pitch blade for an aircraft turbomachine, this blade comprising:

[0019] - a fibrous structure comprising an aerodynamically profiled blade connected to a base, the base comprising a tubular attachment portion centered on a stabilizer axis and comprising an internal housing, centered on the stabilizer axis,

[0020] - a tubular metal sleeve, this sleeve being mounted around the attachment portion and having an axial connecting end located on the side opposite the blade of the fibrous structure,

[0021] - an insert centered on the alignment axis and inserted axially into the internal housing of the attachment portion,

[0022] - a polymerized resin for solidifying the fibrous structure and bonding the fibrous structure to the insert and the sleeve, and

[0023] - an eccentric attached and fixed to the base of the fibrous structure, this eccentric comprising a first annular part centered on the alignment axis and coupled by a first coupling link with the axial end of the sleeve, and a second part connected to the first part and defining an articulation axis which is at a distance from the alignment axis,

[0024] the first part of the eccentric being further coupled by a second coupling link with the attachment portion and / or the insert, the first and second coupling links being independent.

[0025] The invention thus proposes a second coupling link, independent of the first, between the eccentric and the attachment portion and / or the insert. Advantageously, the first coupling link is not designed to transmit torque around the alignment axis, whereas the second coupling link is designed to transmit this torque. It is therefore understood that this torque will no longer be transmitted from the sleeve to the eccentric, but will instead be transmitted from the attachment portion and / or the insert to the eccentric. The first coupling link can therefore be simplified and have only an indexing function, for example, and / or a function of transmitting bending forces at the interface between the eccentric and the sleeve, which appear, for example, when the eccentric is acted upon. The blade according to the first aspect of the invention may comprise one or more of the following features, taken individually or in combination:

[0026] - the first coupling link is a link through cooperation of forms;

[0027] - the first mating link is of the curvic-coupling® type or dogging or male-female;

[0028] - the second coupling link is made by means of a grooved ring which is centered on the alignment axis, this ring being rotationally fixed to the eccentric around the alignment axis and having coupling grooves with the attachment portion and / or the insert;

[0029] - the coupling splines are engaged in grooves of the attachment portion and / or the insert, the grooves extending parallel to the alignment axis;

[0030] - the grooves are formed both in the attachment portion and the insert, and extend along the alignment axis from axial ends of the attachment portion and the insert, located on the side opposite the blade, the grooves opening radially inwards opposite the alignment axis;

[0031] - the crown is formed from a single piece including the eccentric;

[0032] - the crown is a separate part from the eccentric and coupled to the eccentric by a third coupling link;

[0033] - the third coupling link is a curvic-coupling® type link.

[0034] - the eccentric is fixed to the sleeve by a series of screws or bolts which extend around the alignment axis and parallel to this alignment axis; - the screws or bolts pass through the first holes of the eccentric and the second holes of a ring located inside the axial end of the sleeve;

[0035] - the ring is formed in one piece with the sleeve; - the ring is formed in one piece with the crown;

[0036] -- the ring is an independent part of the sleeve and is engaged by axial translation in the axial end of the sleeve, and retained axially in this axial end, in a direction opposite to the blade, by an annular ring which extends around the alignment axis and is intercalated radially between the ring and the axial end of the sleeve;

[0037] -- the screws or bolts are axially covered by a free end of the fastening portion;

[0038] -- the crown is at least partially engaged in the housing of the attachment portion;

[0039] -- the housing of the attachment portion opens axially onto a free end of the attachment portion, opposite the blade;

[0040] -- the first and second parts of the eccentric being formed from a single piece.

[0041] According to a second aspect, the invention relates to a variable-pitch blade for an aircraft turbomachine, this blade comprising;

[0042] - a fibrous structure comprising an aerodynamically profiled blade connected to a base, the base comprising a tubular attachment portion centered on a stabilizing axis and comprising an internal housing,

[0043] - a tubular metal sleeve, this sleeve being mounted around the attachment portion and having an axial connecting end located on the side opposite the blade of the fibrous structure,

[0044] - an insert centered on the alignment axis and inserted axially into the housing of the attachment portion,

[0045] - a polymerized resin for solidifying the fibrous structure and bonding the fibrous structure to the insert and the sleeve, and

[0046] - an eccentric attached and fixed to the base of the fibrous structure, this eccentric comprising a first annular part centered on the alignment axis and coupled by a first coupling link with the axial end of the sleeve, and a second part connected to the first part and defining an articulation axis which is at a distance from the alignment axis,

[0047] The eccentric is attached to the sleeve by a series of screws or bolts that extend around and parallel to the alignment axis. The tightening and fastening forces of the eccentric to the sleeve are thus distributed around the alignment axis. This type of fastening is more compact and lighter than other types of fastening.

[0048] The blade according to the second aspect of the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0049] - the screws or bolts pass through the first holes of the eccentric and the second holes of a ring located inside the axial end of the sleeve;

[0050] - the ring is formed in one piece with the sleeve;

[0051] - the ring is presented in the form of an annular strap, for example scalloped;

[0052] - the second orifices of the ring are formed by notches which open radially inwards with respect to the alignment axis;

[0053] - the screws or bolts are axially covered by a free end of the fastening portion;

[0054] - the ring is located at an axial distance from the free end of the attachment portion, measured along the alignment axis, which is less than a length of the screws or bolts;

[0055] - each screw or bolt includes a head located on the side of the attachment portion and bearing against the ring;

[0056] - the screw heads cooperate with the ring by complementary shapes to immobilize the screws in rotation around screw axes;

[0057] - the screws or bolts each include a head located on the opposite side to the attachment portion and bearing on the first part of the eccentric; - the screws are screwed into nuts which are carried by the ring and which cooperate by complementary shapes with the ring to immobilize the nuts in rotation around screwing axes;

[0058] - the nuts are crimped into the second holes of the ring;

[0059] - the first coupling link is a link by cooperation of shapes and in particular a link of the curvic-coupling® type.

[0060] The characteristics of both aspects of the invention can be combined together.

[0061] The present invention also relates to a propeller for an aircraft turbomachine, comprising several blades as described above, a hub having mounting and rotational guidance holes for the feet of these blades, and a blade pitch control actuation mechanism which is surrounded by the hub and is articulated to the second part of each of the eccentrics of these blades.

[0062] The present invention also relates to an aircraft turbomachine, comprising blades or a propeller as mentioned above.

[0063] Brief description of the figures

[0064] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0065] [Fig.1] Figure 1 is a schematic axial cross-sectional view of a blade for an aircraft turbomachine,

[0066] [Fig. 2] Figure 2 is a larger-scale view of part of Figure 1 and shows the blade foot mounted in an opening in a propeller hub. [Fig. 3] Figure 3 is a view similar to that of Figure 2 and shows another embodiment.

[0067] [Fig. 4] Figure 4 is a schematic axial cross-sectional view of the root of a turbine blade for an aircraft turbomachine. [Fig. 5] Figure 5 is a larger-scale view of a portion of Figure 4.

[0068] [Fig. 6] Figure 6 is a very schematic view of a curvic-coupling® type connection,

[0069] [Fig.7] Figure 7 is a partial schematic axial cross-sectional view of a composite material blade for an aircraft turbomachine;

[0070] [Fig.8] Figure 8 is a schematic cross-sectional and perspective view of the foot of the blade of figure 7;

[0071] [Fig. 9a-9b] Figures 9a and 9b are partial schematic cross-sectional views of a blade according to one embodiment of the invention,

[0072] [Fig. 10a-10b] Figures 10a and 10b are partial schematic cross-sectional views of a blade according to one embodiment of the invention, [Fig. 11] Figure 11 is a partial schematic axial cross-sectional view of the foot of a blade and illustrates another embodiment of the invention, [Fig. 12] Figure 12 is a partial schematic axial cross-sectional and perspective view of a portion of the attachment and an insert of the foot of the blade of Figure 11,

[0073] [Fig. 13] Figure 13 is a schematic cross-sectional view of the foot of the blade in Figure 11, and

[0074] [Fig.14] Figure 14 is a view similar to that of Figure 11 and illustrates another variant embodiment of the invention.

[0075] Detailed description of the invention

[0076] Figure 1 shows a propeller 10 for an aircraft turbomachine, this propeller 10 being shrouded or unshrouded.

[0077] The propeller 10 comprises a hub 12 and blades 14 carried by this hub 12. The hub 12 has a general annular or polygonal shape and extends around a first axis not shown.

[0078] In Figure 1, one of the blades 14 of the propeller 10 is visible, and the hub 12 is shown in axial section, the cutting plane passing through the first axis of the hub 12. The hub 12 has orifices 12a distributed around the first axis, each of these orifices 12a having a substantially radial orientation with respect to this first axis. Each orifice 12a passes radially through the hub 12; that is, each orifice 12a opens radially to the outside and radially to the inside, respectively.

[0079] Each blade 14 comprises a blade 16 and a foot 18. The feet 18 of the blades 14 are respectively engaged in the orifices 12a of the hub 12.

[0080] The blade 16 has an aerodynamic profile and includes an intrados 16a and an extrados (not visible) which are connected by a leading edge 16c and a trailing edge 16d, the terms upstream and downstream referring to the flow of gases around the blade 16 in operation.

[0081] The blade 16 has a free upper end, called the apex, and a lower end that is connected to the foot 18.

[0082] The blade 14 can be made of composite material using an injection molding process called RTM (Resin Transfer Molding). This process involves preparing a fibrous preform by three-dimensional weaving, then placing this preform in a mold and injecting a polymerizable resin, such as an epoxy resin, which will impregnate the preform. After polymerization and hardening of the blade 16, its leading edge 16c is generally reinforced by a metal shield 20, which is attached, for example, by bonding.

[0083] The shield 20 can be made of titanium or titanium alloy, stainless steel, steel, aluminum, nickel, etc. The intrados 16a or even the extrados of the blade 16 can be covered with a polyurethane film 22 for erosion protection.

[0084] A denotes the axis of extension of the blade 14 and the blade 16, and in particular the axis of adjustment of the blade 14, that is to say, the axis around which the angular position of the blade 14 is adjusted. It is generally also a radial axis, thus extending along a radius relative to the first axis.

[0085] As can be seen more clearly in Figure 2, the foot 18 is hollow and includes an internal recess 18a in the example shown. The foot 18 has an elongated, tubular shape, its internal recess 18a being closed on the side of the blade 16 and open on the opposite side.

[0086] The recess 18a of the foot 18 allows to reduce its mass, the shape and dimensions of the foot 18 being optimized to ensure good mechanical support of the blade 14 in operation.

[0087] The foot 18 has in its recess 18a internal grooves 24 which are configured to allow coupling of the foot 18 with a control system for the blade pitching around its pitching axis A (figures 2).

[0088] The grooves 24 extend around the axis A. In the example shown, they are located between two internal cylindrical surfaces 26a, 26b of the recess 18a, located respectively radially outside and inside the grooves 24 with respect to the first axis.

[0089] The foot 18 of the blade 14 further includes at its radially internal free end (opposite the first axis), an annular surface 26c which extends in a plane perpendicular to the axis A.

[0090] The foot 18 of the blade 14 includes one or more stops 28, 30. The stop or each stop 28, 30 has an annular shape and extends around the axis A and radially outwards with respect to this axis A.

[0091] In the example shown, the stop 28 is formed a projection at a radially external end of the foot 18 opposite the first axis, substantially at the level of the closed end of the recess 18a.

[0092] The stop 30 is formed a projection on a median part of the foot 18 opposite the first axis, located between the stop 28 and the free end of the foot 18.

[0093] The foot 18 of the blade 14 also includes an annular groove 32 which opens radially outwards and which is formed here in the vicinity of the free end of the foot 18.

[0094] Between the stop 28 and the groove 32, and more specifically between the stop 30 and the groove 32, the foot 18 comprises an external cylindrical surface 34a, which may or may not have an external thread. The foot 18 of the blade 14 comprises several external cylindrical centering surfaces S1, S2, and S3 in the example shown. The surfaces S1, S2, and S3 have decreasing diameters D1, D2, and D3 and are distributed along axis A, radially from the outside to the inside with respect to the first axis. The surface S1 with the largest diameter D1 is located between the stops 28 and 30. The surface S2 with an intermediate diameter D2 is located between the stop 30 and the surface 34a.

[0095] The surface S3 of smaller diameter D3 is located between the groove 32 and the free end of the foot 18, and more particularly between the groove 32 and another external thread 34b of the foot 18. The thread 34b has a diameter smaller than that of the surface 34a or of the thread provided on this surface.

[0096] The stop 28 is located at the radially external end of surface S1 with respect to the first axis. The stop 30 is located at the radially external end of surface S2 with respect to the first axis.

[0097] The hub 12 may include annular fixing flanges 36 at each of its axial ends, as can be seen in Figure 2. In the example shown, each of the orifices 12a of the hub 12 includes stops 38, 40, 42, 44.

[0098] Each stop 38, 40, 42, 44 has an annular shape and extends around axis A and radially inwards with respect to this axis A.

[0099] The stops 38, 40, 42, 44 are respectively arranged one after the other along the alignment axis A. There is thus a radially external stop 38, a radially internal stop 44 and two intermediate stops 40, 42.

[0100] Stop 38 has a larger diameter than stop 40, and stop 44 has a larger diameter than stop 42.

[0101] The intermediate stops 40, 42 allow to accommodate bearings 46, 48 of guide of the feet 18 of the blades 14.

[0102] Bearings 46 and 48 are two in number and are mounted in the hub opening 12a, arranged radially one outside the other. The outer bearing 46 is designated as the outer bearing, and the inner bearing 48 as the inner bearing.

[0103] Bearings 46, 48 are mounted inside the orifice 12a, bearing axially (with respect to axis A) on the intermediate stops 40, 42. Bearings 46, 48 are mounted around the foot 18, and in particular around the surfaces S1 and S2, bearing axially (with respect to axis A) on the stops 28, 30.

[0104] An intermediate piece is provided between the bearing 48 and the blade root 18, and specifically between the inner ring of the bearing 48 and the surface S2. This is a press-fitted sleeve on the blade root 18, which allows for a harder material than that (for example, titanium) of the root 18 as the bearing surface. Indeed, the inner ring of the bearing 48 cannot have significant shrinkage along its axis because it is displaced during preloading. Therefore, to prevent fretting (material pull-out that would lead to a crack initiation on the blade root), this hard intermediate piece can be added.

[0105] The external bearing 46 is configured to be engaged in the orifice 12a from the outside of the hub 12, by moving it radially from the outside to the inside, until it comes to rest on the stop 40. The bearing 46 is here a ball bearing with angular contact and it is its outer ring that bears against the stop 40.

[0106] The internal bearing 48 is configured to be engaged in the orifice 12a from the inside of the hub, by moving it radially from the inside to the outside, until it comes to rest on the stop 42. The bearing 48 is here a ball bearing, and in particular a double row ball bearing, and with angular contact and it is its outer ring which bears against the stop 42.

[0107] As shown in Figures 1 and 2, the foot 18 of the blade 14 is configured to be engaged in the orifice 12a by translation along axis A, radially from the outside to the inside with respect to the first axis, inside the bearings 46 and 48, until the thrust bearing 28 bears axially (with respect to axis A) on the bearing 46, and in particular its inner ring, and the thrust bearing 30 bears axially (with respect to axis A) on the bearing 48, and in particular its inner ring. The bearings 46 and 48, and in particular their inner rings, are then mounted on the surfaces S1 and S2.

[0108] It is therefore understood that the external bearing 46 has an internal diameter greater than the internal diameter of the internal bearing 48 in order to allow the mounting of the foot 18 in the orifice 12a, insofar as the bearings 46, 48 are mounted prior to the foot 18 in the example shown.

[0109] The stop 28 of the foot 18 can bear directly (along axis A) on the external bearing 46 and in particular its inner ring. In the example shown, the stop 28 bears on the external bearing 46 by means of an external annular cover 50 which is mounted around the foot and which at least partially covers the external bearing 46.

[0110] This outer cover 50 has its inner periphery clamped between the stop 28 and the outer bearing 46, and in particular its inner ring. The outer periphery of the cover 50 bears in the direction of axis A on the hub 12 and in particular on the stop 38, either directly or via an annular seal 52 as illustrated in the drawing.

[0111] The stop 30 of the foot 18 can bear directly (along axis A) on the internal bearing 48 and in particular its inner ring. In the example shown, the stop 30 bears on the internal bearing 48 via an annular seal 54.

[0112] An internal annular cover 56 can also be mounted around the foot 18 and cover at least part of the internal bearing 48.

[0113] The inner cover 56 has its outer periphery bearing in the direction of axis A on the hub 12 and in particular on the thrust bearing 44, either directly or via an annular seal 58 as illustrated in the drawing. Alternatively, the outer periphery of the cover 56 could bear in this direction on the inner bearing 48, and in particular on the outer ring of this bearing. The inner periphery of the cover 56 bears radially with respect to axis A on the foot 18, near its free end, either directly or via an annular seal 60 as illustrated in the drawing. In the example shown, the inner cover 56 comprises at least two teeth 62, 64 oriented radially towards axis A.

[0114] The inner cover 56 may further include an internal cylindrical centering surface 56a configured to cooperate with a complementary external cylindrical surface of the inner bearing 48, and for example, of the inner ring of this bearing. This surface 56a may be located on the inner periphery of an internal annular web of the cover 56. This web may include through ports 65 for the passage of fluid, and in particular, lubricating oil for the bearings 46, 48.

[0115] The foot 18 is retained in the orifice 12a of the hub 12 by a retention system which essentially comprises a ring 66 and a screw-nut assembly 68. It is this screw-nut assembly 68 which allows a preload to be applied to the foot of the blade.

[0116] Ring 66 is mounted around foot 18 of the blade and extends around axis A. Ring 66 is sectorized and therefore comprises ring sectors arranged circumferentially end to end around axis A. The number of sectors is not limited and can be reduced to two. Ring 66 then comprises two half-rings.

[0117] Alternatively, the ring could be continuous and not segmented. It could then include a slot to allow elastic deformation of the ring by separating its longitudinal ends.

[0118] The ring 66 is configured to be engaged in the groove 32 of the foot 18. It is understood that the segmentation of the ring 66 allows its mounting in the groove 32. The ring 66 comprises an inner periphery housed in the groove 32 and an outer periphery intended to remain outside the groove 32 to form an axial stop (with respect to axis A). The screw-nut assembly 68 comprises an internal screw 68a and an external nut 68b. The internal screw 68a has an external thread 68a1 and may include an internal thread 68a2 or, alternatively, an internal cylindrical surface. When the screw 68a has an internal cylindrical surface, this surface is intended to cooperate by sliding with the surface 34a of the foot during the mounting and positioning of the assembly 68 on the foot. When the screw 68a includes an internal thread 68a2, the foot includes a thread on its surface 34a and the thread 68a2 is used for screwing the nut 68a onto the thread of the foot 18.

[0119] The external nut 68b has an internal thread 68b1 for screwing onto the external thread 68a1 of the internal screw 68a.

[0120] Positioning (by simple sliding or screwing / unscrewing) the internal screw 68a on the foot 18 allows it to be moved axially (relative to the axis A) on the foot 18 and positioned along the axis A. The screw 68a is able to bear against the ring 66 on the opposite side of the blade 16 in the direction of the axis A.

[0121] The screwing / unscrewing of the external nut 68b allows it to be moved axially (relative to the axis A) on the nut 68a and to be positioned along the axis A. The external nut 68b is able to bear in the direction of the axis A on the internal bearing 48, and in particular on its inner ring, on the side of the blade 16.

[0122] The double support of the screw-nut assembly 68, respectively on the ring 66 and the bearing 48, and the screwing of the external nut 68b onto the internal screw 68a, allows a certain preload to be applied to the foot 18 of the blade by the retaining system.

[0123] In the example shown in Figure 2, the internal screw 68a includes an annular rim 70 which is located on the opposite side to the blade 16 and which extends around the outer periphery of the ring 66 to prevent the ring 66 from accidentally coming out of the groove 32.

[0124] The screw 68a and the nut 68b each comprise a series of teeth 72, 74 oriented radially outwards with respect to the axis A and configured to cooperate with the teeth 62, 64 of the inner cover 56 in order to immobilize the assembly 68 in rotation around the axis A.

[0125] The series of teeth 74 of the external nut 68b is located on the side of the blade 16 and is configured to cooperate with the tooth 64 of the hood 56. The series of teeth 72 of the internal screw 68a is located on the opposite side of the blade 16 and is configured to cooperate with the tooth 62 of the hood 56.

[0126] In the example shown, the set of teeth 72 has an external diameter smaller than that of the set of teeth 74.

[0127] The propeller 10 also includes a control system 76 for adjusting the blade pitch 14, which is associated with the blade's foot 18. The propeller 10 therefore comprises as many control systems 76 as there are blades 14 of this propeller. Each control system 76 includes an eccentric 78, the first part of which, formed by a bushing 80, is engaged by translation along the axis A inside the recess 18a of the foot 18, radially from the inside to the outside with respect to the first axis.

[0128] The socket 80 has external grooves 82 configured to engage in the internal grooves 24 of the foot 18.

[0129] The sleeve 80 further comprises external cylindrical centering surfaces 80a, 80b which cooperate with the surfaces 26a, 26b of the recess 18a when the sleeve 80 is inserted into the recess 18a. These surfaces 80a, 80b are located on either side of the grooves 82 along the axis A.

[0130] In the example shown, the socket 80 also includes an external annular rim 84.

[0131] A nut 86 is screwed onto the thread 34b of the foot, at its free end, and includes an internal annular rim 86a which bears in the direction of axis A on the external rim 84 of the bushing 80, and in the direction of the blade 16 to retain the bushing 80 in the recess 18a of the foot 18.

[0132] The nut 86 bears in the direction of axis A on the inner periphery of the inner cover 56, either directly or via an annular seal 88. The nut 86 may include a series of teeth 90 extending radially outwards with respect to axis A, to allow the nut 86 to engage with a tool for screwing and unscrewing the ring.

[0133] Figure 2 illustrates a solution for coupling the eccentric 78 to the foot 18 of the blade 14, which consists of providing an internal coupling to the foot via the grooves 24, 82.

[0134] Figure 3 illustrates another solution of the prior art for coupling the eccentric 78 to the foot 18 of the blade 14, which consists of providing a coupling by splines 24, 82 at a longitudinal end of the foot 18. Although the splines 24, 82 have a length L2 less than that L1 of Figure 2, these splines are associated with cylindrical centering surfaces 80a, 80b which are arranged on either side of the splines 24, 82 and result in an extension of the total length L3 of the coupling between the eccentric 78 and the foot 18 of the blade.

[0135] We now refer to figures 4 and 5 which illustrate another 114 blade with variable pitch.

[0136] This dawn 114 includes:

[0137] - a blade 16 (not visible in figure 4 but similar to that in figure 1), - a foot 18 defining a stabilization axis A, and

[0138] - an eccentric 78 attached and fixed to foot 18.

[0139] The eccentric 78 comprises a first annular part 78a centered on the alignment axis A and coupled to the foot 18, and a second part 78b connected to the first part 78a and defining an articulation axis B which is at a distance from the alignment axis A.

[0140] The articulation axis B can be parallel to the alignment axis A, as seen in Figure 4, or inclined with respect to this axis, as is the case in Figure 2.

[0141] The first and second parts 78a, 78b of the eccentric 78 are formed from a single piece as seen in figure 2. The first part 78a of the eccentric 78 is coupled to the foot 18 by means of a link 100 here of the curvic-coupling® type.

[0142] A link 100 of this type is formed by a first annular row of teeth 102 carried by the eccentric 78 and a second annular row of teeth 104 carried by the foot 18, these teeth 102, 104 being more visible in figures 5 and following.

[0143] The teeth 102 of the first row are distributed around the alignment axis A and are axially oriented opposite the teeth 104 of the second row so as to be able to engage axially between the teeth 104 of the second row. The teeth 104 of the second row are therefore also distributed around the alignment axis A.

[0144] The distribution of teeth 102, 104 around axis A is preferably regular. The number of teeth 102, 104 per row can be greater than 30 or 50, for example.

[0145] The particularity of the teeth 102, 104 of a link 100 of this type is that the teeth of one of the rows have first lateral flanks 106a, 106b of torque passage which are concave curved (figure 6), and that the teeth of the other of the rows have second lateral flanks 108a, 108b of torque passage which cooperate by support in circumferential direction with the first lateral flanks 106a, 106b and which are convex curved (figure 6).

[0146] The flanks 106a, 106b are complementary to the flanks 108a, 108b.

[0147] It is therefore understood that, according to a first embodiment, the concave curved lateral flanks 106a, 106b can be located on the teeth 102 of the eccentric 78, and the convex curved lateral flanks 108a, 108b can be located on the teeth 104 of the foot 18.

[0148] Alternatively, the concave curved side flanks 106a, 106b can be located on the teeth 104 of the foot 18, and the convex curved side flanks 108a, 108b can be located on the teeth 102 of the eccentric 78. The first row of teeth 102 is preferably located at one end of a cylindrical wall 110 of the first part 78a of the eccentric 78 (figure 5).

[0149] The eccentric 78 is preferably held fixedly on the foot 18 by a nut 86. The nut 86 is screwed onto the foot 18 and bears axially on the eccentric 78 to keep the eccentric 78 axially tightened on the foot 18 with respect to the alignment axis A.

[0150] The first part 78a of the eccentric 78 preferably includes a radially internal annular rim 112 on which this nut 86 bears axially. As in the example shown, the nut 86 can bear axially on an internal periphery of the annular rim 112.

[0151] This annular rim 112 can extend radially inwards from the aforementioned cylindrical wall 110 of the first part 78a of the eccentric 78. This annular rim 112 preferably includes a lateral annular face 112a located on the side of the foot 18, which is situated in a plane P1 perpendicular to the alignment axis A which passes through a base of the teeth 102 of the first row.

[0152] The second row of teeth 104 is preferably located at one end of a first cylindrical wall 116 of the foot 18.

[0153] The foot 18 preferably includes a second cylindrical wall 118 surrounded by the first cylindrical wall 116 and having a thread 120 for screwing the nut 86.

[0154] A device 122 for locking the nut 86 against rotation vis-à-vis the foot 18 around the shimming axis A is preferably further provided, in particular at the free end of the wall 118.

[0155] Furthermore, the example shown in Figure 4 shows that the foot 18 includes annular bearing surfaces or stops 40, 42 for mounting roller bearings 48, 50. The second row of teeth 104 is advantageously located at a longitudinal end of the foot 18 that is axially offset from these bearing surfaces or stops 40, 42. In general, the curvic-coupling® type coupling is considered to have both a high power transmission capacity and to ensure good alignment accuracy between components. This coupling is considered self-centering due to the shape of the opposing concave and convex complementary teeth.

[0156] Figures 7 and 8 show a 214 blade made of composite material.

[0157] The blade 214 has a sleeve 215 which has a recess 217 delimited by an internal wall 219 of the sleeve 215. The recess 217 passes through the sleeve 215 along a shimming axis A.

[0158] The blade 214 also includes a fibrous structure 221, for example, obtained by weaving fibers (UD laminates, 2D, braids and 3D weaves, etc.). The fibrous structure 221 includes a foot 223 comprising a fastening portion 225 configured to be inserted into the recess 217 of the sleeve 215.

[0159] The attachment portion 225 of the fibrous structure 221 has a tubular shape and includes a housing 227 centered on the alignment axis A.

[0160] The fibrous structure 221 also includes a blade 229 with an aerodynamic profile connected to the base 223.

[0161] The blade 214 also includes an insert 231 which is configured to be inserted into the internal housing 227 of the attachment portion 225 so that the attachment portion 225 is radially interposed between the insert 231 and the internal wall 219 of the sleeve 215.

[0162] The blade 214 further includes a polymerized resin for solidifying the fibrous structure 221 and for bonding the insert 231 to the fibrous structure 221 and to the inner wall 219 of the sleeve 215.

[0163] The resin thus makes it possible to form a main force path, called default, when transmitting a torque recovery force around the alignment axis A between the foot 223 and the sleeve 215.

[0164] The blade 214 is thus formed from a few elements that fit together to form a single-piece blade. Since the blade 229 and the foot 223 are formed from the same fibrous structure 221, there is no discontinuity between the blade 229 and the foot 223. Furthermore, the foot 223 is wedged between the insert 231 and the sleeve 215, and the fibrous structure 221 is thus securely bonded to the foot 223.

[0165] The 214 blade can thus withstand significant aerodynamic stresses while maintaining a limited mass, and can therefore be used with a variable pitch mechanism and in an open rotor environment. Furthermore, since the components of the 214 blade are limited in number, it is quick to manufacture.

[0166] The resin typically comprises an organic material (thermoset, thermoplastic, or elastomer) or a carbon matrix. For example, the matrix may comprise a plastic material, typically a polymer, such as epoxy, bismaleimide, or polyimide. The fibers of the fibrous structure 221 comprise at least one of the following materials: carbon, glass, aramid, polypropylene, and / or ceramic.

[0167] The attachment portion 225 may include an additional thickness 233 resulting from a progressive thickening of the fibrous structure 221 forming said attachment portion 225, at its free end opposite the blade 229. This additional thickness 233 is preferably configured to fit into a recessed portion of the inner wall 219. Thus, this recessed portion widens the recess 217 and the remainder of the wall portion 219 narrows the recess 217. In this way, when the insert 231 is positioned in the recess 217, any translation of the attachment portion 225 away from the free end of the attachment portion 225 is prevented by the wall portion 219 which narrows the recess 217 and forms a stop.

[0168] Indeed, when the fan is rotating, the blade 214 is subjected to centrifugal forces oriented in a radial direction relative to the axis of rotation of the fan, which tend to separate the blade 229 from the sleeve 215. The extra thickness 233 helps to prevent the separation of the blade 229 and the sleeve 215. It is the span angle which also contributes to retention, a composite of constant thickness remaining blocked by the presence of this span.

[0169] The 215 sleeve is preferably metallic and monolithic.

[0170] The insert 231 comprises a cylindrical body having a free end 235 and a locking end 237 opposite the free end 235. It is understood that the insert 231 advantageously has a shape corresponding to the tubular shape of the internal housing 227. The tubular geometry maximizes the moment of inertia and the working surface of the attachment portion 225 within the sleeve 215, which is preferably cylindrical. Furthermore, the axisymmetric shape of the insert 231 is advantageously optimized for significant torsional forces or leading-edge / trailing-edge bending. In addition, the shape of the insert 213 allows, for example, control of composite skin thicknesses and / or contribution to the mechanical strength of the blade (lifespan and / or frequency distribution). The locking end 237 is rounded or pointed in the example shown, but could alternatively have another shape. Insert 231 is preferably metallic.

[0171] As can be seen in Figure 8, the attachment portion 225 of the fibrous structure 221 may have, over at least part of its length along the alignment axis A, a non-cylindrical external surface 239. Furthermore, the inner wall 219 of the sleeve 215 covers this external surface 239 and preferably has a shape complementary to this external surface 239.

[0172] In the example shown, the external surface 239 of the attachment portion 225 has, in cross-section with respect to the alignment axis A, a generally polygonal shape, in particular a 6-sided shape. The internal wall 219 of the sleeve 215 covers this external surface 239 without play and has a complementary generally polygonal shape, in particular a 6-sided shape.

[0173] It can be seen that this shape is devoid of sharp edges and includes, for example, rounded corners at the corners of the polygon. The rounded corners preferably have a radius of curvature between 2 and 20 mm, and preferably between 10 and 20 mm. In the example shown, the external surface 239 is located at the outer periphery of the aforementioned overthickness 233.

[0174] Reference is now made to figures 9a and 9b which illustrate an embodiment according to one aspect of the invention.

[0175] In this embodiment, the blade 214 is as described above with reference to figures 7 and 8. The blade 214 thus comprises a fibrous structure 221 whose attachment portion 225 is radially intercalated between an insert 231 and a sleeve 215.

[0176] Furthermore, the blade 214 includes an eccentric 278 which is similar to the eccentric 78 described above with reference to figures 1 to 6. The eccentric 278 includes a first annular part 278a centered on the alignment axis A, and a second part 278b connected to the first part 278a and defining a aforementioned articulation axis B which is at a distance from the alignment axis A.

[0177] The distinctive feature of this eccentric 278 is that it is coupled to the sleeve 215, here by a curvic-coupling® type connection. The preceding description concerning this type of connection therefore applies to this embodiment. The sleeve 215 extends axially along the alignment axis A, in a direction opposite to the blade, beyond the free ends of the attachment portion 225 and the insert 231.

[0178] The free end of the sleeve 215, opposite the blade, includes an annular edge on which the teeth 104 of the second row are formed. The teeth 102 of the first row are carried by the eccentric 278, and in particular its first part 278a, as mentioned above. The preceding description, made with reference to Figure 6, applies to this embodiment.

[0179] In figures 9a and 9b, the eccentric 278 is fixed to the foot and in particular to the sleeve 215 by a series of screws 241 or bolts which extend around the alignment axis A and parallel to this alignment axis A. In the example shown, the screws 241 or bolts pass through the first holes 243 of the eccentric 278 and the second holes 245 of a ring 247 located inside the axial end of the sleeve 215.

[0180] Ring 247 can be in the form of an annular strap, for example scalloped, as is the case in the example shown.

[0181] Furthermore, the ring 247 is preferably formed in one piece with the sleeve 215, as is also the case in the example shown. In the example shown, it can also be seen that each of the screws 241 comprises a head 241a located on the blade side and a threaded rod 241b which is screwed into a nut 249. The head 241a of each screw 241 bears against the ring 247, and each nut 249 bears against the eccentric 278. The heads 241a of the screws 241 may include flats which cooperate with the ring 247 for the purpose of securing the screws 241 around their thread axes.

[0182] The drawings show that the screws 241 are axially covered by the free end of the attachment portion 225.

[0183] It can also be seen that the distance X1, measured along axis A, between the ring 247 and the free end of the attachment portion 225, is less than the length X2 of the screws 241 and in particular of their threaded rods 241b. During assembly and in particular the positioning of the first part 278a of the eccentric 278 on the sleeve 215, the screws 241 which are free to slide in the holes 245 are prevented from coming out axially from these holes by bearing axially through their heads 241a on the free end of the attachment portion 225 (thanks to the fact that X1 < X2). Furthermore, to facilitate or even permit the mounting of the screws 241 in the holes 245, these holes 245 can be formed by notches which open radially inwards in the direction of the axis A. It is thus understood that the screws 241 can be mounted in the holes 245 by translation in a radial direction from the inside to the outside.The variant embodiment of figures 10a and 10b differs from the embodiment previously described essentially in that the directions of the screws 241 or bolts are reversed.

[0184] Each screw 241 comprises a head 241a located on the side opposite the blade and a threaded shank 241b which is screwed into a nut 249 located on the blade side. The head 241a of each screw 241 bears against the eccentric 278 and each nut 249 bears against the ring 247.

[0185] The nuts 249 can be secured to the ring 247 and can, for example, be captive. The nuts 249 are then, for example, crimped into the holes 245 of the ring.

[0186] Unlike the previous embodiment, the orifices 245 are not necessarily formed by notches here.

[0187] The nuts 249 may include flats which cooperate with the ring 247 for the purpose of immobilizing the nuts 249 around the screw axes.

[0188] Reference is now made to figures 11 to 14 which illustrate an embodiment according to one aspect of the invention.

[0189] In this embodiment, the blade 214 is as described above with reference to Figure 7. In this embodiment, the blade 214 does not necessarily conform to Figure 8 because the attachment portion 225 does not necessarily have a polygonal external surface. The external shape of the attachment portion 225 is preferably cylindrical.

[0190] The blade 214 thus comprises a fibrous structure 221 whose attachment portion 225 is radially intercalated between an insert 231 and a sleeve 215.

[0191] Furthermore, the blade 214 includes an eccentric 278 which is similar to the eccentric 78 described above with reference to Figures 1 to 6. The distinctive feature of this eccentric 278 is that it is coupled to the sleeve 215 by a first coupling link C1.Tl

[0192] We can also see that the first part 278a of the eccentric 278 is further coupled by a second coupling link C2 with the attachment portion 225 and / or the insert 231.

[0193] The first and second coupling links C1, C2 are advantageously independent.

[0194] The first coupling link C1 is preferably a joint based on the cooperation of forms, the purpose of which is to index the eccentric 278 relative to the foot. This means that the aim here is not to transmit a particular force but only to correctly position the eccentric 278 relative to the sleeve 215, in particular around the alignment axis A.

[0195] The first C1 mating link can be of the curvic-coupling® type or dog-clutching or male-female.

[0196] On the contrary, the transmission of forces will here be carried out through the second coupling link C2, between the fibrous structure (or also the insert 231) and the eccentric 278.

[0197] The second coupling link C2 can be made by means of a grooved ring 251 which is centered on the alignment axis A.

[0198] The crown 251 is at least partially engaged in the housing of the attachment portion 225.

[0199] The ring 251 is preferably rotationally fixed to the eccentric 278 around the alignment axis A and has splines 253 for coupling with the attachment portion 225 and / or the insert 231, as can be seen more clearly in Figure 13.

[0200] The splines 253 are preferably engaged in grooves 255 of the attachment portion 225 and / or the insert 231. As shown in Figures 12 and 13, the grooves 255 extend parallel to the alignment axis A. The grooves 255 are preferably formed in both the attachment portion 225 and the insert 231, and extend along the alignment axis A from the axial ends of the attachment portion 225 and the insert 231, located on the side opposite the blade. The grooves 255 open radially inward with respect to the alignment axis A. The grooves 255 are preferably machined during the manufacturing of the blade.

[0201] In the example shown in Figure 11, the crown 251 is formed in one piece with the eccentric 278.

[0202] In the variant shown in Figure 14, the crown 251 is an independent part of the eccentric 278 and is coupled to the eccentric 278 by a third coupling link C3. This third coupling link C3 can be a curvic-coupling® type link.

[0203] It is therefore understood that the transmission of forces is carried out here through the coupling links C2 and C3, from the fibrous structure (or even the insert 231) to the eccentric 278 via the ring 251.

[0204] In the embodiment examples in Figures 11 and 14, the eccentric 278 is fixed to the sleeve 215 by a series of screws 241 or bolts similar to those described above.

[0205] The 241 screws or bolts extend around the alignment axis A and parallel to this alignment axis A.

[0206] The screws 241 or bolts pass through the first holes 243 of the eccentric 278 and the second holes 245 of the ring 247 located inside the axial end of the sleeve 215.

[0207] The particularity of the embodiment variants of figures 11 and 14 is related to the fact that the ring 247 is an independent part of the sleeve 215 and is engaged by axial translation in the axial end of the sleeve 215, and retained axially in this axial end, in a direction opposite to the blade, by an annular ring 257, preferably split, which extends around the alignment axis A and is intercalated radially between the ring 247 and the axial end of the sleeve 215.

[0208] In the case of Figure 11, the ring 247 is further independent of the crown 251 and the eccentric 278. In this case, the ring 247, preferably equipped with screws 241 or bolts, is first engaged in the sleeve 215, then the circlip 257 is mounted in the sleeve 215 to axially retain the ring 247 in the sleeve 215. The eccentric 278 with the crown 251 is then mounted and fixed on the foot.

[0209] In the case of figure 14, the ring 247 is formed in one piece with the crown 251. In this case, the crown 251 with the ring 247, preferably equipped with screws 241 or bolts, are engaged in the sleeve 215, then the circlip 257 is mounted in the sleeve 215 to axially retain the crown 251 with the ring 247 in the sleeve 215. The eccentric 278 is then mounted and fixed on the foot.

[0210] The screws 241 or bolts are axially covered by a free end of the attachment portion 225 and are arranged as in the case of figures 9a and 9b.

[0211] The embodiment variants of figures 11 and 14 thus propose to create a direct force path between the attachment portion 225 and the eccentric 278 via the ring 251. The ring 251 allows the aforementioned torque to pass through by complementary shapes with the attachment portion 225.

[0212] The attachment portion 225 can be pre-machined to form a specific recess so that the composite part works in conjunction with the ring 251. It is also possible to machine the insert 231 to contribute to torque absorption. However, if it is desired to distance it from the load path (to separate the functions), an alternative is to maintain it at an axial distance from the grooves 255 of the attachment portion 225, or to circumferentially oversize the grooves 255 of the insert 231 relative to those of the attachment portion 225.

[0213] The number and shape of the teeth of the grooves 253 of the crown 251 are variable:

[0214] The number of teeth in the grooves 251 can be between 2 and 10; the teeth in the grooves 253 can have sharp, beveled or radiating edges.

[0215] - the top of the teeth can also have a slope or radius so as not to generate stresses in the composite material or an excessively abrupt transition in stiffness or torsion, and

[0216] - The tooth thickness can decrease towards the bottom of the grooves (255), again to manage a gradual stiffness transition. If the tooth thickness is constant, they can be assembled with the attachment portion in a tight fit (see "tight fit") to eliminate play at the interface. If the tooth thickness decreases, play between the teeth and the attachment portion can be eliminated during assembly by creating a slope in the contact surfaces. This is possible thanks to axial mounting with a screw connection.

[0217] The first coupling link C1 remains present between the external sleeve 215 and the eccentric 278 to prevent relative movements between the foot 223 and the sleeve 215 that would promote fretting wear. Another function of this coupling could be to absorb bending moments.

[0218] Compared to prior art solutions, the present invention guarantees a load path that ensures torque transfer around the alignment axis. This direct load path reduces the risk of failure and simplifies the manufacturing and testing of the blade root compared to the state of the art. It is important to note that this solution can be advantageous for reducing the overall size of the blade root because the torque transfer function is performed very close to the alignment axis.

Claims

DEMANDS 1. Variable-pitch blade (214) for an aircraft turbomachine, this blade (214) comprising: - a fibrous structure (221) comprising a blade (229) with an aerodynamic profile connected to a foot (223), the foot (223) comprising a tubular attachment portion (225) centered on a shimming axis (A) and comprising an internal housing (227) centered on the shimming axis (A), - a tubular metallic sleeve (215), this sleeve being mounted around the attachment portion (225) and having an axial connecting end located on the side opposite the blade (229) of the fibrous structure (221), - an insert (231) centered on the alignment axis (A) and inserted axially into the internal housing (227) of the attachment portion (225), - a polymerized resin for solidifying the fibrous structure (221) and for bonding the fibrous structure (221) to the insert (231) and the sleeve (215), and - an eccentric (278) attached and fixed to the foot (223) of the fibrous structure, this eccentric (278) comprising a first annular part (278a) centered on the alignment axis (A) and coupled by a first coupling link (C1) with the axial connecting end of the sleeve (215), and a second part (278b) connected to the first part (278a) and defining an articulation axis (B) which is at a distance from the alignment axis (A), the first part (278a) of the eccentric (278) being further coupled by a second coupling link (C2) with the attachment portion (225) and / or the insert (231), the first and second coupling links (C1, C2) being independent.

2. Blade (214) according to the preceding claim, wherein the first coupling link (C1) is a link by cooperation of forms having the purpose of indexing the eccentric (278) with respect to the foot (223).

3. Blade (214) according to the preceding claim, wherein the first coupling link (C1) is of the curvic-coupling® or dog clutch or male-female type.

4. Blade (214) according to any one of the preceding claims, wherein the second coupling link (C2) is made by means of a grooved ring (251) which is centered on the shim axis (A), this ring (251) being rotationally fixed to the eccentric (278) around the shim axis (A) and having splines (253) for coupling with the attachment portion (225) and / or the insert (231).

5. Blade (214) according to the preceding claim, in which the coupling grooves (253) are engaged in grooves (255) of the attachment portion (225) and / or of the insert (231), the grooves (255) extending parallel to the alignment axis (A).

6. Blade (214) according to the preceding claim, wherein the grooves (255) are formed both in the attachment portion (225) and the insert (231), and extend along the alignment axis (A) from axial ends of the attachment portion (225) and the insert (231), located on the side opposite the blade (229), the grooves (255) opening radially inwards with respect to the alignment axis (A).

7. Blade (214) according to any one of claims 4 to 6, wherein the crown (251) is formed in one piece with the eccentric (278).

8. Blade (214) according to any one of claims 4 to 6, wherein the crown (251) is an independent part of the eccentric (278) and coupled to the eccentric (278) by a third coupling link (C3).

9. Blade (214) according to the preceding claim, wherein the third coupling link (C3) is a curvic-coupling® type link.

10. Blade (214) according to any one of the preceding claims, wherein the eccentric (278) is fixed to the sleeve (215) by a series of screws (241) or bolts which extend around the alignment axis (A) and parallel to this alignment axis (A).

11. Blade (214) according to the preceding claim, wherein the screws (241) or bolts pass through first orifices (243) of the eccentric (278) and second orifices (245) of a ring (247) located inside the axial end of the sleeve (215).

12. Blade (214) according to claim 11, wherein the ring (247) is formed in one piece with the sleeve (215).

13. Blade (214) according to claim 11, depending on claim 8, wherein the ring (247) is formed in one piece with the crown (251).

14. Propeller (10) for an aircraft turbomachine, comprising several blades (214) according to any one of the preceding claims, a hub (12) comprising mounting and rotational guidance ports (12a) for the feet (223) of these blades (214), and a blade pitch control actuation mechanism which is surrounded by the hub (12) and which is articulated to the second part (278b) of each of the eccentrics (278) of these blades (214).

15. Aircraft turbomachine, comprising blades (214) according to any one of claims 1 to 13 or a propeller (10) according to claim 14.

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