Aircraft turbine engine including variable pitch propeller blades

Abstract

The present invention relates to an assembly comprising a propeller blade (10) and a system (34) for angularly adjusting the pitch of the blade (10), the system comprising a bowl (42) radially defined by an annular wall (44) extending about an axis (A) for adjusting the pitch of the blade (10), the bowl (42) comprising a bottom wall (46), the free lower end (28) of a root (14) being axially fitted into a complementary receiving portion (56) of the bottom wall (46) to rotatably connect the bowl (42) and the blade (10) about the pitch adjustment axis (A), characterized in that the root (14) of the blade (10) comprises a first limiting surface (70A) which engages with a first abutting surface (72A) of the bowl (42) in the event that the lower end (28) of the root breaks to limit the rotation of the blade (10).

Description

Technical Field

[0001] This invention relates to the field of aircraft turbine engines, and particularly to propulsion propellers of such turbine engines including variable pitch blades. Background Technology

[0002] The propeller of an aircraft turbine engine can be ducted (e.g., in the case of a fan) or unducted (e.g., in the case of an open rotor architecture).

[0003] A propeller comprises blades, and the blades can have a variable pitch. Therefore, a turbine engine includes a pitch setting system that allows the pitch angle of the blades to be changed so that the thrust generated by the propeller can be adapted to different stages of flight.

[0004] The introduction of the blade pitch setting system implies the provision of a safety device known as the feathering system. This system allows the blade to return to a safe feathering pitch angle in the event of a failure in the pitch setting system, which minimizes aerodynamic drag. Failures can include, for example, malfunctions in the kinematic chain components or damage to the actuators.

[0005] This safety device is necessary because propeller blades operating at unintended pitch angles can degrade engine performance. For example, this can lead to efficiency losses and reduced maneuverability. In some cases, blades at unsuitable pitch angles for flight conditions can even generate excessive drag, making the aircraft uncontrollable. This is why such excessive drag is classified as a "hazardous propeller effect" by the Propeller Certification Specification (a regulation issued by the European Aviation Safety Agency, EASA).

[0006] If the propeller blades were considered flat plates, the feathering pitch angle would align the blades with the engine shaft (with the chord parallel to the engine shaft). However, propeller blades typically have a natural twist. Therefore, the feathering pitch angle is determined at a specific section of the blade (the section whose chord will align with the engine shaft), for example, a section of the blade taken at approximately 75% of its length from the hub.

[0007] Safety devices that enable automatic feathering of blades can be of various types: mechanical systems with counterweights, hydraulic systems, etc. The most common solution is to position the counterweight attached to the blade at a well-defined angular position that allows the blade to be brought back to the blade's pitch angle, known as "feathering," by the inertial effect of the propeller's rotational speed.

[0008] Offset counterweight systems are also known. In this case, the restoring torque generated by the counterweight is transmitted to the impeller blades via a kinematic chain (e.g., via gears). The addition of counterweight also makes it possible to reduce the power of the actuator in the pitch setting system.

[0009] When the counterweight is not attached to the blades, the restoring torque toward the feathering pitch angle is transmitted by the components forming the kinematic chain. Therefore, if one of these intermediate components fails, the feathering capability will be lost.

[0010] The present invention aims to find a solution to address the situation where the blade pitch angle is out of control due to a failure in the kinematic chain components between the actuators of the blade and the pitch setting system and / or between the blade and the safety device. Summary of the Invention

[0011] The present invention proposes an assembly for an aircraft turbine engine, the assembly including a propeller blade and a system for setting the pitch of the blade about a pitch setting axis. The blade has a root extending from an upper end to a free lower end, the upper end being connected to the blade. The system for setting the pitch of the blade includes a cup portion radially defined by an annular wall extending about the pitch setting axis. The cup portion includes a bottom wall and an upper opening. The root portion is intended to be axially inserted into the cup portion through the upper opening. The free lower end of the root portion is axially embedded in a receiving portion complementary to the bottom wall to rotatably connect the cup portion and the blade about the pitch setting axis.

[0012] The component according to the invention is characterized in that the root of the blade includes at least one first radial limiting surface, which is used to engage with at least one associated first radial stop surface of the cup in the event of a failure at the lower end of the root, so as to limit the rotation of the blade relative to the cup in a first direction about the pitch setting axis.

[0013] This allows for a second path to transmit the pitch setting control torque to the blades in the event of a failure at the free lower end, which is typically ensured by the free lower end.

[0014] According to another feature of the invention, the root of the blade includes at least one second radial limiting surface, which is used to engage with at least one associated second radial stop surface of the cup in the event of a failure at the lower end of the root, to limit the rotation of the blade relative to the cup in a second direction about the pitch setting axis.

[0015] This allows for control of the rotation of the blade's pitch setting axis in both directions in the event of a failure at the free lower end of the root.

[0016] According to another feature of the invention, when the blade is rotatably connected to the cup via the free lower end of the blade, the angular space is retained between each radial limiting surface and the stop surface associated with each radial limiting surface.

[0017] This ensures that the blades can be easily installed in the cup. Furthermore, it ensures that during normal operation, the blade pitch setting control torque is transmitted only through the lower end of the root.

[0018] According to another feature of the invention, the angular space is between 2° and 10°, preferably 5°.

[0019] This allows for sufficient clearance to install the blades, while limiting the angular deflection of the blades in the cup in the event of a failure at the lower end of the root.

[0020] According to another feature of the invention, the component includes a retaining device for axially attaching the root to the cup portion.

[0021] According to another feature of the invention, the root has a protruding extension called a "spherical portion", which is axially arranged between the blade and the free lower end. The pitch setting system includes an annular retaining ring configured to be installed inside the cup portion and to engage with the annular walls of the spherical portion and the cup portion respectively, so as to axially fix the root to the cup portion.

[0022] According to another feature of the invention, the stop surface and the limiting surface are axially arranged below the retaining ring.

[0023] According to another feature of the invention, the limiting surface is generally arranged at the level where the spherical portion has the maximum radial dimension.

[0024] In another feature of the invention, the root portion includes a body portion which is housed in an annular cylindrical portion before the root portion is inserted into the cup portion, and each limiting surface is integrally formed with the cylindrical portion.

[0025] According to another feature of the invention, at least one first limiting surface and at least one second limiting surface are arranged on a common limiting finger that projects radially outward relative to the root.

[0026] According to another feature of the invention, the limiting finger is received in a corresponding stop recess of the cup portion, the corresponding stop recess being circumferentially defined by a first stop surface and a second stop surface.

[0027] According to another feature of the invention, radial space is preserved between the inner surfaces of the annular wall that restricts the finger portion and the cup portion.

[0028] According to another feature of the invention, at least one first stop surface and at least one second stop surface are arranged opposite to each other on a common stop finger that projects radially inward relative to the annular wall of the cup portion.

[0029] According to another feature of the invention, the stop finger is received in a corresponding limiting recess at the root, the corresponding limiting recess being circumferentially defined by a first limiting surface and a second limiting surface.

[0030] According to another feature of the invention, radial space is preserved between the stop finger and the root. Attached Figure Description

[0031] Other features and advantages of the invention will become apparent from the following detailed description, with reference to the accompanying drawings, in which:

[0032] Figure 1 This is a schematic perspective view of a propeller blade for an aircraft turbine engine and illustrates the invention.

[0033] Figure 2 yes Figure 1 A magnified view of a portion of the blades, showing the root of the blades.

[0034] Figure 3 It is based on Figure 4 A cross-sectional view of plane 3-3, which shows Figure 1 The impeller blades are attached to the root of the cup in the pitch setting system.

[0035] Figure 4 It is based on Figure 3 A cross-sectional view of the plane Pb, showing the shape and position of the free lower end of the root relative to the pitch setting axis.

[0036] Figure 5 It is along Figure 4 Axial torque view taken from cross section 5-5.

[0037] Figure 6 This illustrates an alternative embodiment of the pitch setting system, and... Figure 3 Similar views,

[0038] Figure 7 It is based on Figure 3 A schematic cross-sectional view of the cross-sectional plane Pm, which schematically illustrates a first embodiment of the invention, in which the root of the impeller includes a limiting finger received in a stop recess of the cup portion.

[0039] Figure 8 This schematically illustrates the second embodiment of the invention, and... Figure 7In a similar view, in a second embodiment of the invention, the root of the impeller includes a limiting notch in which the stop finger of the cup is received.

[0040] Figure 9 Is Figure 3 The enlarged view shown in box 9 shows the limiting surface at the root and the stop surface at the cup.

[0041] Figure 10 This illustrates an alternative embodiment of the root of the blade, and... Figure 2 In a similar view, in this alternative embodiment, the root is equipped with a cylindrical portion.

[0042] Figure 11 yes Figure 10 An exploded view of the root section and showing the two shell halves of the cylindrical section.

[0043] Figure 12 It is based on Figure 3 A cross-sectional view of the cross-sectional plane Pm, which illustrates the application of the present invention to... Figure 10 The first embodiment of the root,

[0044] Figure 13 It is based on Figure 3 A cross-sectional view of the cross-sectional plane Pm, which illustrates the application of the present invention to... Figure 10 The second embodiment of the root. Detailed Implementation

[0045] In the following description, elements with the same structure or similar function will be represented by the same reference numerals.

[0046] In the remainder of the specification, an axial direction is used, in a non-limiting manner, extending upwards (near the free end of the blade) along the pitch setting axis "A" of the blade. A radial direction is also used, extending outwards from the inside (near the pitch setting axis) orthogonally to the pitch setting axis. A circumferential direction is also used, along an arc centered on the pitch setting axis "A". Therefore, the circumferential direction is orthogonal to the radial and axial directions.

[0047] Figure 1 The image shows the blade 10 of a propeller for an aircraft turbine engine, which can be either ducted or unducted. As an example, the propeller in this case is not unducted.

[0048] The impeller 10 includes blades 12 that extend approximately along axis "A" and connect to root 14. Axis "A" is the extension axis of impeller 10 and blades 12, and in particular, the pitch setting axis "A" of impeller 10, which is the axis around which the pitch angle of impeller 10 is adjusted. This axis is approximately an axis extending radially from the axis of rotation of the propeller equipped with the impeller 10.

[0049] The blade 12 has an aerodynamic profile and includes a sulcus 12a and a back 12b, which are connected by an upstream leading edge 12c and a downstream trailing edge 12d, the terms upstream and downstream referring to the flow of gas around the blade 12 during operation. The chord of the blade 12 section, selected orthogonally to the pitch setting axis "A", is defined as the straight line connecting the leading and trailing edges.

[0050] The blade 12 has a free upper end, referred to as the top, and a lower end connected to the root 14.

[0051] In the example shown, the blade 10 is made of composite material by an injection molding method known as resin transfer molding (RTM). This method involves preparing a fiber preform 18 by three-dimensional weaving, then arranging the preform in a mold and injecting a polymerizable resin, such as epoxy resin, to impregnate the preform. After the blade 12 has cured and hardened, the leading edge 12c of the blade is typically reinforced by a metal sheath 20, which is assembled and attached, for example, by gluing.

[0052] The blade 10 includes a sparsity 22. The sparsity 22 includes a portion that forms the core of the blade 12. The portion of the sparsity 22 that forms the core of the blade 12 is intended to be inserted into the preform 18 prior to resin injection. The sparsity 22 also includes a portion that extends on the side of the blade 12 opposite to the top to form a root 14.

[0053] Preferably, the spar 22 is made of a composite material. For example, the composite material is a composite material having an epoxy organic matrix reinforced with 3D woven carbon fibers, wherein, at the height of the aerodynamic channel, the warp direction is oriented primarily along the pitch setting axis "A", and the weft direction is oriented primarily along the chord of the blade 12.

[0054] Alternatively, the spar can also be formed by mechanically more advantageous assembly of different organic matrix composites (thermosetting, thermoplastic, or elastomers), which are reinforced with long fibers (carbon, glass, aramid, polypropylene) having various fiber arrangements (braiding, knitting, unidirectional).

[0055] Although not shown, the blade 12 may be hollow or solid and includes an inner cavity filled with a foam or honeycomb filler material. This filler material is mounted around the spar 22 and covered with a skin made of an organic matrix composite material to increase the impact resistance of the blade 12.

[0056] The sheath 20 can be made of titanium or titanium alloy, stainless steel, steel, aluminum, nickel, etc. The arched belly 12a or even the arched back 12b of the blade 12 can be covered with a polyurethane film to resist corrosion.

[0057] The root 14 includes a main body 24, the main body having in Figure 2 The specific shape is best seen in the center. The main body 24 is integrally formed with the wing spars 22. The main body 24 basically consists of three parts:

[0058] - The free lower end 28 is positioned opposite the blade 12.

[0059] - Upper column 30, the upper column is located on one side of blade 12, and

[0060] - A protruding extension, referred to as the "spherical part" 32, is located between the free end 28 and the column part 30.

[0061] Preferably, the main body 24 is solid, that is, the main body does not have a hollow groove portion.

[0062] The cross-section of the free end 28 is typically non-circular, and in this case, polygonal. (As in...) Figure 4 and Figure 5 As shown, the free end 28 is offset from the pitch setting axis "A" to achieve proper positioning (détrompage) or indexage, which will be explained in more detail below.

[0063] Reference Figure 3 Pb is defined as a transverse plane, that is, a plane perpendicular to the pitch setting axis "A", which passes approximately through the middle of the free lower end 28 measured along the pitch setting axis "A". This plane Pb is referred to as the lower plane or the bottom plane. Figure 4 The cross-sectional shape of the free end 28 in the plane Pb is shown. This cross-section, referred to as the lower section, has a value or surface area (e.g., maximum value) and is typically rectangular in the example shown.

[0064] As will be described below, the free lower end 28 is configured to cooperate with a system 34 for setting the pitch of the blade 10.

[0065] Refer again Figure 2The column portion 30 has a relatively complex shape, which allows for a transition between the root portion 14 and a portion of the spar 22 that forms the core of the blade 12. (See reference...) Figure 3 Ph is defined as a transverse plane passing through the column portion 30 (specifically through the lower extension of the column portion). This plane Ph is referred to as the high plane or upper plane. In this plane, the column portion 30 may have a non-circular cross-sectional shape, such as oval, elliptical, square, or rectangular. This cross-section, referred to as the high section, has a value or surface area (e.g., a maximum value).

[0066] The spherical portion 32 has a generally convex shape or a dome shape, which extends about the pitch axis “A”.

[0067] Pm is specifically defined as passing through the intermediate plane of the spherical portion 32 at the portion of the spherical portion having the largest cross-section (hereinafter referred to as the intermediate section). This plane Pm is referred to as the intermediate plane. In this plane, the cross-section of the spherical portion 32 may have a circular shape, but this cross-section is not limiting.

[0068] It should be understood that plane Pm lies between plane Pb and plane Ph. The maximum cross-sectional dimension of the spherical portion 32 decreases from plane Pm to plane Ph, and decreases further from plane Pm toward plane Pb.

[0069] The blade 10 is intended to be mounted in a pitch setting system 34, which allows the blade's pitch angle to be varied relative to the propeller hub 36 about a pitch setting axis "A". The pitch angle is defined as the angle formed by a chord of a given section relative to the axis of rotation of the propeller (not shown), such that the given section is, for example, located at 75% of the length of the blade 12 measured from the root 14. A pitch angle of 0° will be referred to hereinafter as a "feather" pitch angle.

[0070] For this purpose, the pitch setting system 34 includes bearings 38 and 40. Here, there are two bearings 38 and 40, namely a lower bearing 38 and an upper bearing 40.

[0071] Bearings 38 and 40 are ball bearings. In the example shown, the bearings have different diameters, and the balls in the bearings also have different diameters.

[0072] The lower bearing 38 extends generally between plane Pm and plane Pb, and thus extends around the lower portion of the spherical portion 32. The diameter of the lower bearing 38 is smaller than that of the upper bearing 40, and the diameter of the balls in the lower bearing is larger than that of the balls in the upper bearing 40.

[0073] The lower bearing 38 is also of the angular contact type. In the example shown, the bearing point or bearing surface of the ball on the raceway of the ball rings 38a, 38b is located on the truncated conical surface S1, which extends along the pitch setting axis "A", and the maximum diameter of the truncated conical surface is located on the top side of the blade 10.

[0074] The upper bearing 40 extends generally between plane Pm and plane Ph, and thus extends around the upper portion of the spherical portion 32. The upper bearing 40 is also of angular contact type. In the example shown, the bearing point or bearing surface of the ball on the raceway of the ball rings 40a, 40b is located on the truncated conical surface S2, which extends along the pitch setting axis "A", and the maximum diameter of the truncated conical surface is located on one side of the free end 28 of the root 14 of the impeller 10.

[0075] Figure 3 An example embodiment of the pitch setting system 34 is shown.

[0076] The pitch setting system 34 includes a cup portion 42 that forms a pitch pivot relative to the hub around the axis "A" of the blade 10. The cup portion 42 includes an annular wall 44 extending around the pitch setting axis "A". The annular wall 44 radially defines the internal volume of the cup portion 42. The internal volume of the cup portion 42 is closed by a bottom wall 46 that extends relative to the free end 28 of the root portion. The cup portion 42 has an opening 48 at its upper axial end, which is radially defined by the upper end edge of the annular wall 44. The free lower end 28 of the root portion 14 and the spherical portion 32 are intended to be axially inserted into the cup portion 42 through the upper opening 48.

[0077] The annular wall 44 and the bottom wall 46 are made into one piece.

[0078] exist Figure 3 As can be seen, the cup portion 42 is designed to support the bearings 38 and 40, which ensure that the cup portion 42 is centered and guided relative to the hub portion 36 of the turbine engine around the pitch axis "A".

[0079] Bearings 38 and 40 can form part of the pitch setting system 34. Specifically, at least one of the guide bearings 38 and 40 can have an inner ring integrated into the cup portion 42. The same applies to the lower bearing 38, whose inner ring 38b is integrated into the cup portion 42. In effect, this means that the cup portion 42 includes a raceway on its outer periphery, on which the balls of the lower bearing 38 roll directly. This raceway includes an annular surface with a concave curved cross-section. This raceway is located at the lower end of the cup portion 42 and the annular wall 44. The outer ring 38a of the bearing 38 is attached to the hub portion 36, for example, by a preload fit. Furthermore, advantageously, the cup portion 42 is designed to apply prestress to the bearing 38.

[0080] The outer ring 40a of the bearing 40 is attached to the hub 36, for example, by a preload fit. The inner ring 40b of the bearing engages with the free upper ends of the cup 42 and the annular wall 44 and is engaged around the free upper ends of the cup and the annular wall. This end of the annular wall 44 includes an outer cylindrical surface 50 for mounting the inner ring 40b and external threads for screwing on a nut 52, which is intended to axially support the inner ring 40b to keep the inner ring axially clamped against the outer cylindrical shoulder 54 of the cup 42.

[0081] Advantageously, a shim 55 is axially arranged between the inner ring 40b and the outer cylindrical shoulder 54. This shim 55 is designed to compensate for manufacturing tolerances in the hub 36 by adjusting the position of the inner ring 40b. In particular, this allows for the application of optimal preload to the lower rolling bearing 38 when the nut 52 is clamped.

[0082] The bottom wall 46 of the cup portion 42 is configured to fit into the free lower end 28 of the root portion 14 in a shape-fitting manner, so that the cup portion 42 is fixed in the rotational direction relative to the root portion 14 about the pitch axis "A".

[0083] In this context, it should be understood that the bottom wall 46 includes a receiving portion 56 having a cross-section complementary to the cross-section of the free lower end portion 28 of the root portion 14. Therefore, the cross-section of the receiving portion 56 is non-circular, and in particular rectangular. Thus, the receiving portion 56 is configured to receive the free lower end portion 28, as in... Figure 3 , Figure 4 as well as Figure 5 As shown in [the image / document]. Figure 4 and Figure 5 As can be seen, the receiving portion 56 is eccentrically positioned relative to the pitch axis "A" in a manner similar to that of the free lower end portion 28. This eccentricity allows for rotation and proper positioning when the root portion 14 is inserted into and installed in the cup portion 42, and ensures that the free lower end portion 28 has only one engagement position in the receiving portion 56.

[0084] The receiving portion 56 is located on the upper or inner surface of the bottom wall 46 of the cup portion 42, so the receiving portion is located inside the cup portion 42 and is oriented to the side of the root portion 14.

[0085] The pitch setting system 34 generates torque at the root 14 of the blade 10, which counteracts the torsional torque generated by aerodynamic forces and centrifugal forces. Advantageously, the free lower end 28 is directly embedded into the receiving portion 56 without the need for inserts to directly restrict the rotation of the root 14. This provides a more direct force path, allowing the torsional torque to be applied directly to the root 14.

[0086] The bottom wall 46 includes a lower or outer surface located on the side opposite to the root 14, and includes a cylindrical extension 58 extending along the pitch setting axis "A" and including an external thread or external straight spline 60 for rotatably connecting the pitch setting system 34 to an actuator that enables control of the pitch angle via a transmission mechanism not shown.

[0087] The pitch setting system 34 also includes a retaining device for axially attaching the root portion 14 to the cup portion 42. For this purpose, the pitch setting system 34 includes an annular retaining ring 62 configured to be mounted within the cup portion 42 and to engage with both the spherical portion 32 and the annular wall 44 of the cup portion 42, thereby axially retaining the root portion 14 within the cup portion 42. The retaining ring 62 allows the root portion 14 to be axially fixed to the cup portion 42 only, and the root portion 14 is fixed in rotation relative to the cup portion 42 by embedding its lower free end portion 28 into the receiving portion 56.

[0088] In a non-restrictive example, Figure 3 In the embodiment shown, the retaining ring 62 is a dog-tooth clutch ring, which includes an outer dog tooth portion 64 configured to engage with a complementary inner dog tooth portion 66 of the annular wall 44 of the cup portion 42. An elastic member 68 is arranged between the root portion 14 and the bottom wall 46 of the cup portion 42 to force the root portion 14 against the retaining ring 62, which itself presses against the inner dog tooth portion 66 of the cup portion 42 to provide axial fixation of the root portion 14 within the cup portion 42.

[0089] In the fixed ring 62 Figure 6 In the alternative embodiment shown, the retaining ring 62 has a wedge-shaped cross-section and is configured to be axially biased outward from the cup portion 42 under the action of centrifugal force during operation, and to keep the root portion 14 of the impeller 10 axially clamped by the wedge effect.

[0090] The actuator of the pitch setting system 34 may malfunction. In this case, a safety device (not shown) is provided to enable the blade 10 to return to the "feather" pitch angle of the blade, thereby limiting the effect of drag on the blade 10 and thus enabling the pilot to maintain control of the aircraft.

[0091] As a non-limiting example, the safety device includes a counterweight that is movable about an axis and continuously recovers toward a safe position under the action of the propeller's rotation, the safe position corresponding to the feathering pitch angle of the blade 10. Therefore, the counterweight generates a restoring torque about its axis of rotation. During normal operation of the pitch setting system 34, the actuator has sufficient power to overcome the restoring torque and thus control the blade 10 to the desired pitch angle.

[0092] The arrangement of the root 14 within the cup 42 does not allow sufficient space to directly attach the counterweight to the root 14 of the blade 10. Therefore, the counterweight is attached to the outside of the cup 42. The counterweight can be rotatably mounted about an axis other than the pitch setting axis "A", or the counterweight can be rotatably mounted about the pitch setting axis "A", for example, by attaching it to the cup 42. In all cases, the restoring torque is transmitted to the root 14 via the cup 42.

[0093] As previously explained, the cup portion 42 and the root portion 14 of the blade 10 are fixed in rotation by the free lower end portion 28 of the root portion 14. In the event of a failure in the free lower end portion 28 of the root portion 14 of the blade 10, for example along the broken line indicated by the reference numeral "R", although the blade is still axially held in the cup portion 42 by the engagement between the retaining ring 62 and the spherical portion 32, the blade 10 will rotate freely relative to the cup portion 42 about the pitch setting axis "A". In this case, neither the torque provided by the actuator nor the restoring torque provided by the counterweight can be transmitted to the blade 10, and the blade may rotate uncontrollably in the cup portion 42. Although the probability of this occurring is very low, it is preferable to provide a backup solution to restore control of the direction of the blade 10 about the pitch setting axis "A" of the blade.

[0094] To address this problem, the present invention proposes providing a secondary path for transmitting torque between the cup portion 42 and the root portion 14 in the event of a failure in the free lower end portion 28. Figure 7 and Figure 8 Two alternative embodiments illustrating the principles of the present invention are shown below.

[0095] For this purpose, the root 14 of the blade 10 includes at least one first radial limiting surface 70A, which is designed to cooperate with at least one first associated radial stop surface 72A of the cup portion 42 in the event of a failure of the free lower end 28 of the root 14, in order to limit the rotation of the blade 10 relative to the cup portion 42 about the pitch setting axis "A" in the first direction "SA".

[0096] The first direction of rotation, "SA", corresponds to the direction of rotation that causes the propeller blade 10 to return towards the pitch angle of the blade when it is in a feathering angle to generate thrust and move the aircraft forward. Therefore, the restoring torque generated by the safety device tends to cause the blade 10 to rotate in the first direction of rotation, "SA".

[0097] However, sometimes aerodynamic torque is applied to the blade 10 via airflow. The total torque that can be applied to the blade 10 (i.e., the sum of restoring torque and aerodynamic torque) may also tend to cause the blade 10 to rotate in a second direction "SB" opposite to the first direction "SA".

[0098] In this regard, preferably, the root 14 of the blade 10 includes at least one second radial limiting surface 70B, which is designed to engage with at least one associated second radial stop surface 72B of the cup portion 42 in the event of a failure of the free lower end 28 of the root 14, to limit the rotation of the blade 10 relative to the cup portion 42 about the pitch setting axis "A" in the second direction "SB".

[0099] When the impeller 10 is rotatably connected to the cup portion 42 via the free lower end 28 of the impeller, the angular space “Jc” is circumferentially retained between each radial limiting surface 70A, 70B and its associated stop surface 72A, 72B.

[0100] The corner space “Jc” was chosen to allow for easy installation between the root 14 and the cup 42.

[0101] Furthermore, the angular space "Jc" ensures that when the root 14 is rotatably connected to the cup 42 via the free lower end 28 of the root, no force will be transmitted through the radial surface 70 and the stop surfaces 72A, 72B.

[0102] The angular space “Jc” also makes it easy to check for faults in the free lower end 28 of the root 14, because by simply applying manual force to rotate the blade 10, it can be seen that the blade 10 has a rotational deflection relative to the cup 42 around the blade pitch setting axis “A”.

[0103] However, the angular space “Jc” must be kept small enough to limit aerodynamic imbalances and vibrations during propeller operation.

[0104] Preferably, the angular space "Jc" is between 2° and 10°. Preferably, the angular space is equal to 5°.

[0105] As in Figure 3 As shown in, and as in Figure 9 As shown in more detail, in order to benefit from better leverage, the limiting surfaces 70A and 70B are arranged approximately at the plane “Pm”, where the spherical portion 32 has its maximum radial dimension. The stop surfaces 72A and 72B and the limiting surfaces 70A and 70B are arranged axially below the retaining ring 62.

[0106] exist Figure 3 and Figure 6 In the embodiment shown, the root portion 14 generally comprises two parts: a body 24 and an annular cylindrical portion 26, the annular cylindrical portion extending along an axis "A" about the pitch of the body 24 and the blade 10. The annular cylindrical portion 26 is attached to the body 24.

[0107] Preferably, the cylinder portion 26 is independent of the pitch setting system 34.

[0108] As in Figure 10 and Figure 11 As shown in more detail, the cylindrical portion 26 is made of two shell halves 26a and 26b, as in... Figure 3 As can be seen, the two shell halves are assembled and attached to the body 24, for example, one shell halves are on the side of the ventral 12a of the blade 12, and the other shell halves are on the side of the convex 12b of the blade 12. Thus, the shell halves 26a and 26b are joined at a joint plane that passes through the pitch setting axis "A" and extends approximately parallel to the chord of the blade 12.

[0109] Advantageously, the barrel 26 is attached to the body 24 by adhesive bonding. The adhesive extends between the barrel 26 and the body 24 around the pitch setting axis "A".

[0110] Preferably, the cylindrical portion 26 is made of metal (steel, titanium, or titanium alloy, such as TA6V). The adhesive is, for example, an epoxy resin adhesive filled with thermoplastic or elastomeric sections, or a fiber-reinforced epoxy resin adhesive. This adhesive bonding method is particularly suitable due to the large contact surface area between the cavity of the cylindrical portion 26 and the body 24 (which can be a composite material).

[0111] As in Figure 3 and Figure 6 As can be seen, the cylindrical portion 26 covers and fits at least a portion of the column portion 30 and the spherical portion 32. The cylindrical portion has a cross-sectional shape at the intermediate plane "Pm" that is complementary to the spherical portion 32 and at the top cross-section "Ph" that is complementary to the column portion 30.

[0112] The cylindrical portion 26 includes two cylindrical surfaces 67A and 67B for mounting preload assembly rings 69A and 69B. The preload assembly rings enable the housing halves 26a and 26b to be held abutting against each other and against the main body 24. The preload assembly rings 69A and 69B extend along an axis “A” about the pitch.

[0113] Here, each limiting surface 70A, 70B is integrally formed with the cylindrical part 26.

[0114] exist Figure 7 The general principle of the first embodiment of the present invention is shown in the figure, and in Figure 12 The diagram illustrates the application of a first embodiment of the invention to a root portion 14 comprising a cylindrical portion 26. According to this first embodiment, the root portion 14 is provided with a limiting finger 74, which projects radially outward to a free outer end. The limiting finger 74 is defined in one direction by a first limiting surface 70A and in another direction by a second limiting surface 70B. Therefore, the first limiting surface 70A and the second limiting surface 70B rotate in two opposite directions on the common limiting finger 74. Here, the limiting finger 74 protrudes from the outer surface of the cylindrical portion 26.

[0115] Advantageously, such as in Figure 12 As shown, the root portion 14 is equipped with a plurality of limiting fingers 74 to distribute force around the pitch setting axis "A". For example, the limiting fingers 74 are regularly arranged around the pitch setting axis "A".

[0116] The root 14 is equipped with two limiting fingers 74 arranged opposite to the pitch setting axis "A".

[0117] Each limiting finger 74 is received in a corresponding stop recess 76, which is formed in the inner surface of the annular wall 44 of the cup portion 42. The stop recess 76 is circumferentially limited in the first direction "SA" by a first stop surface 72A, which is intended to limit the rotation of the blade 10 in the first direction "SA" by contacting the corresponding first limiting surface 70A, and the stop recess is circumferentially limited in the second direction "SB" by a second stop surface 72B, which is intended to limit the rotation of the blade 10 in the second direction "SB" by contacting the corresponding second limiting surface 70B.

[0118] As previously explained, when the root 14 of the impeller 10 is rotatably connected to the cup 42 via the lower free end 28 of the root, the limiting finger 74 is received between the two stop surfaces 72A, 72B in a circumferentially deflected manner, such that the angular space “Jc” is circumferentially retained between each limiting surface 70A, 70B of the limiting finger 74 and the corresponding stop surface 72A, 72B of the stop recess 76. More specifically, the limiting finger 74 is therefore arranged approximately equidistant from the two stop surfaces 72A, 72B of the corresponding stop recess 76.

[0119] The radial space "Jr" is also retained between the free outer end of the limiting finger 74 and the bottom of the stop recess 76, which is formed in the inner surface of the annular wall 44 of the cup portion 42. This radial space "Jr" is formed to facilitate the installation of the root 14 in the gap of the cup portion 42.

[0120] In addition, in order to allow the root 14 to be axially inserted into the cup 42, the stop recess 76 is axially opened upward to axially receive the limiting finger 74.

[0121] The second embodiment of the present invention is a mechanical reversal of the first embodiment, in Figure 8 The general principle of the second embodiment of the present invention is shown in the figure. Figure 13 The second embodiment of the invention is shown in relation to the root portion 14, which includes the cylindrical portion 26. Here, stop surfaces 72A and 72B are arranged on the stop fingers 78, while limiting surfaces 70A and 70B define limiting recesses 80 formed in the root portion 14.

[0122] The annular wall 44 of the cup portion 42 is equipped with a stop finger 78, which protrudes radially inward to its free inner end. The stop finger 78 is defined in one direction by a first stop surface 72A and in another direction by a second stop surface 72B. Therefore, the first stop surface 72A and the second stop surface 72B rotate in two opposite directions on the common stop finger 78. Here, the stop finger 78 protrudes from the inner surface of the annular wall 44 of the cup portion 42.

[0123] Advantageously, such as in Figure 13 As shown, the cup portion 42 is equipped with a plurality of stop fingers 78 to distribute force around the pitch setting axis "A". For example, the stop fingers 78 are regularly arranged around the pitch setting axis "A".

[0124] The cup section 42 is equipped with two stop fingers 78 arranged opposite each other with respect to the pitch setting axis "A".

[0125] Each stop finger 78 is received in a corresponding limiting recess 80, which is formed in the outer surface of the root portion 14, and here in the outer surface of the cylindrical portion 26. The limiting recess 80 is circumferentially limited in the first direction "SA" by a first limiting surface 70A, which is intended to limit the rotation of the blade 10 in the first direction "SA" by contacting the corresponding first stop surface 72A, and the limiting recess is circumferentially limited in the second direction "SB" by a second limiting surface 70B, which is intended to limit the rotation of the blade 10 in the second direction "SB" by contacting the corresponding second stop surface 72B.

[0126] As previously explained, when the root 14 of the impeller 10 is rotatably connected to the cup 42 via the lower free end 28 of the root, the stop finger 78 is received between two stop surfaces 72A, 72B in a circumferentially deflected manner, such that the angular space “Jc” is circumferentially retained between each stop surface 72A, 72B of the stop finger 78 and the corresponding limiting surfaces 70A, 70B of the limiting recess 80. More specifically, the stop finger 78 is therefore arranged approximately equidistant from the two limiting surfaces 70A, 70B of the corresponding limiting recess 80.

[0127] The radial space “Jr” is also retained between the free inner end of the stop finger 78 and the bottom of the limiting notch 80, which is formed in the outer surface of the root 14. This radial space is formed to facilitate the installation of the root 14 in the gap of the cup 42.

[0128] In addition, in order to allow the root 14 to be inserted axially into the cup 42, the recess 80 is restricted to open axially downward to receive the stop finger 78.

Claims

1. An assembly for an aircraft turbine engine, the assembly comprising a propeller blade (10) and a system (34) for setting the pitch of the propeller blade (10) about a pitch setting axis (A), the propeller blade (10) having a root (14) extending from an upper end to a free lower end (28), the upper end being connected to blades (12) of the propeller blade (10), the system (34) for setting the pitch of the propeller blade (10) comprising a cup (42), wherein... The cup portion is radially defined by an annular wall (44) extending around the pitch setting axis (A), the cup portion (42) includes a bottom wall (46) and an upper opening (48), the root portion (14) is intended to be axially inserted into the cup portion (42) through the upper opening, the free lower end portion (28) of the root portion (14) is axially embedded in a receiving portion (56) complementary to the bottom wall (46) to rotatably connect the cup portion (42) and the propeller blade (10) around the pitch setting axis (A). Its features are, The root (14) of the propeller blade (10) includes at least one first radial limiting surface (70A) for engaging with at least one associated first radial stop surface (72A) of the cup portion (42) in the event of a failure at the free lower end (28) of the root, to limit the rotation of the propeller blade (10) relative to the cup portion (42) about the pitch setting axis (A) in a first direction (sA).

2. The component according to claim 1, characterized in that, The root (14) of the propeller blade includes at least one second radial limiting surface (70B) for engaging with at least one associated second radial stop surface (72B) of the cup portion (42) in the event of a failure at the free lower end (28) of the root to limit the rotation of the propeller blade (10) relative to the cup portion (42) about the pitch setting axis (A) in a second direction (sB).

3. The component according to claim 1 or 2, characterized in that, When the propeller blade (10) is rotatably connected to the cup portion (42) via the free lower end (28) of the propeller blade, the angular space (Jc) is retained between each radial limiting surface (70A, 70B) and the radial stop surface (72A, 72B) associated with each radial limiting surface.

4. The component according to claim 3, characterized in that, The angular space (Jc) is between 2° and 10°.

5. The component according to claim 1 or 2, characterized in that, The component includes a retaining device for axially attaching the root (14) to the cup (42).

6. The component according to claim 5, characterized in that, The root (14) has a protruding extension called a "spherical part" (32), which is axially arranged between the blade (12) and the free lower end (28). The pitch setting system (34) includes an annular retaining ring (52) configured to be installed in the cup (42) and to engage with the annular wall (44) of the spherical part (32) and the cup (42) respectively to axially fix the root (14) to the cup (42).

7. The component according to claim 6, characterized in that, The radial stop surfaces (72A, 72B) and the radial limiting surfaces (70A, 70B) are axially arranged below the retaining ring (52).

8. The component according to claim 6, characterized in that, The radial limiting surfaces (70A, 70B) are arranged at the level of the spherical portion (32) with the maximum radial dimension.

9. The component according to claim 1 or 2, characterized in that, The root (14) includes a body (24) which is housed in an annular cylindrical portion (26) before the root is inserted into the cup portion (42), and each radial limiting surface (70A, 70B) is integrally formed with the annular cylindrical portion (26).

10. The component according to claim 2, characterized in that, The at least one first radial limiting surface (70A) and the at least one second radial limiting surface (70B) are arranged on a common limiting finger (74) that protrudes radially outward relative to the root.

11. The component according to claim 10, characterized in that, The limiting finger (74) is received in the associated stop recess (76) of the cup portion (42), the associated stop recess being circumferentially defined by a first radial stop surface (72A) and a second radial stop surface (72B).

12. The component according to claim 10 or 11, characterized in that, The radial space (Jr) is retained between the inner surface of the restricting finger (74) and the annular wall (44) of the cup (42).

13. The component according to claim 2, characterized in that, The at least one first radial stop surface (72A) and the at least one second radial stop surface (72B) are arranged opposite to each other on a common stop finger (78) that protrudes radially inward relative to the annular wall (44) of the cup portion (42).

14. The component according to claim 13, characterized in that, The stop finger (78) is received in a related limiting notch (80) in the root (14), the related limiting notch being circumferentially defined by a first radial limiting surface (70A) and a second radial limiting surface (70B).

15. The component according to claim 14, characterized in that, The radial space (Jr) is retained between the stop finger (78) and the root (14).

16. The component according to claim 4, characterized in that, The angular space (Jc) is equal to 5°.

Images