System for controlling the pitch setting of the propeller blades of a turboprop engine of an aircraft

Abstract

A system (34) for controlling the pitch setting of a propeller blade (10) of a turbine engine of an aircraft is disclosed, characterized in that it comprises: - a blade (10) comprising a blade (12) connected to a root (14); - a cup (58) comprising an annular wall (58a) extending around a pitch axis (A) of the blade (10) and a lower axial end closed by a bottom wall (58b); - a fixing ring (52) extending around the root (14) and located inside the cup (58); the system further comprises a safety element (110, 110') ensuring the retention of the root (14) with the cup (58), said at least one safety element (110, 110') having a substantially elongated shape and passing through an aligned hole (112, 114, 126) in the bottom wall (58b) of the cup (58) and in the free end (28) of the root (14).

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 prior art specifically includes documents FR-A1-3 017 163 and FR-A1-3 080 322.

[0003] Aircraft turbine engine propellers can be ducted (e.g., in the case of a fan) or non-ducted (e.g., in the case of an open rotor architecture).

[0004] The propeller includes blades, which can have a variable pitch. The turbine engine then includes a mechanism 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.

[0005] Propeller blade design involves multiple disciplines with often conflicting objectives. Propeller blades must be designed to achieve optimal aerodynamic performance (i.e., providing thrust while maximizing efficiency), ensure mechanical strength (i.e., withstand mechanical constraints imposed by static and dynamic loads), and limit mass and acoustic characteristics. Specifically, improvements in propeller aerodynamic performance tend to increase the bypass ratio (BPR), which translates to an increase in the propeller's outer diameter, and consequently, an increase in blade span. However, the increase in BPR occurs simultaneously with a decrease in the fan pressure ratio (FPF). Therefore, pitch-changing systems (variable-pitch blades) are typically required to make the propeller operable throughout its flight domain.

[0006] There are various techniques for attaching variable pitch propeller blades and for controlling the pitch setting of such propeller blades. However, these techniques are relatively complex and expensive. Furthermore, in the event of blade problems, especially damage, particularly when the propeller is not tubular, these techniques cannot guarantee that the blades will remain radially outward relative to the propeller's axis of rotation.

[0007] In the event of a failure in the propeller blade retaining mechanism, ensuring the blade is held in place to prevent it from being ejected outwards and from impacting the fuselage of the turbine-powered aircraft is of paramount importance. This safety feature, known as "failsafe," is not always present in current technology control systems. Control systems that include this feature typically comprise components that are themselves easily detached and could impact the aircraft's fuselage. The larger and denser these components are, the greater the risk of fuselage damage and the greater the need for specialized protective shields, which can affect the aircraft's mass and, consequently, its performance.

[0008] Therefore, a control system technology that integrates simple and effective safety functions is needed. Summary of the Invention

[0009] This invention relates to a system for controlling the pitch setting of propeller blades in an aircraft turbine engine, characterized in that the system comprises:

[0010] - A whorl of blades, comprising blades attached to the root.

[0011] - A cup-shaped portion comprising an annular wall extending around the pitch axis of the impeller, the annular wall comprising a lower axial end closed by a bottom wall and an open upper axial end, the upper axial end being configured such that the root of the impeller can be mounted inside the cup-shaped portion. The bottom wall includes a recess having a non-circular cross-section and is configured to receive a free end of a complementary shape to the root, such that the cup-shaped portion is rotationally secured to the root about the axis.

[0012] - A retaining ring extending about the axis and mounted around the root, the retaining ring being installed within the cup-shaped portion and engaging with the annular walls of both the root and the cup-shaped portion to ensure axial retention of the root within the cup-shaped portion.

[0013] The system also includes at least one safety element that ensures the retention of the root and the cup-shaped portion. The at least one safety element is generally elongated and extends laterally relative to the axis. The at least one safety element passes through the bottom wall of the cup-shaped portion and the alignment hole in the free end of the root.

[0014] Therefore, the safety function of the system is ensured by at least one safety element located at the free lower end of the root of the blade. The safety element has an elongated shape in the transverse direction and a finite overall size. The safety element can be housed within the propeller casing, thus making it unlikely to be ejected in the event of a malfunction. The safety element passes through a transverse hole in the bottom wall of the cup-shaped section and the free end of the root, thus allowing for relatively easy installation, for example, by removing a cover from the aforementioned casing or through a passageway in the casing.

[0015] In this patent application, the lateral direction is defined as the direction perpendicular to the pitch axis of the blade.

[0016] The system according to the invention may include one or more of the following features, either individually or in combination:

[0017] - The at least one safety element is a bolt comprising a screw and a nut, the screw comprising a threaded rod passing through the hole and a head applying pressure against a lateral surface of the bottom wall, the nut being tightened onto the threaded rod and supported against an opposite lateral surface of the bottom wall;

[0018] - The at least one safety element is a stud comprising a cylindrical body that passes through the hole;

[0019] - The at least one safety element passes through a hole at the free end of the root with a predetermined gap;

[0020] - The at least one safety element passes through a hole in the bottom wall of the cup-shaped portion with a predetermined gap;

[0021] - The gaps are the same;

[0022] - The root of the blade includes a body housed in an annular cylindrical portion that extends about the axis and is at least partially housed in the cup-shaped portion. The free end of the root is formed by a protrusion of the body and an axial extension of the cylindrical portion, the protrusion of the body and the axial extension of the cylindrical portion including a hole for the passage of the at least one safety element.

[0023] - The gap between the at least one safety element and the hole in the cylindrical part is smaller than the gap between the at least one safety element and the hole in the protrusion, and preferably the same as the gap between the at least one safety element and the hole in the bottom wall of the cup-shaped part;

[0024] -- The system also includes:

[0025] - A lower rolling guide bearing that extends about the axis and is mounted around the lower portion of the annular wall;

[0026] - An upper rolling guide bearing that extends about the axis and is mounted around the upper portion of the annular wall;

[0027] -- At least one of the guide bearings has an inner ring integrated into the cup-shaped portion;

[0028] -- At least one of the guide bearings is an angular contact bearing;

[0029] -- The concave portion is eccentric relative to the pitch axis;

[0030] -- The system also includes an elastically deformable member that extends about the pitch axis and is mounted inside the cup-shaped portion. The member is axially supported on the bottom wall and configured to axially bias the root of the blade toward the outside of the cup-shaped portion.

[0031] -- The retaining ring is a claw-shaped clutch ring, which includes an outer claw-shaped tooth that is configured to engage with a complementary inner claw-shaped tooth of the annular wall of the cup-shaped portion;

[0032] -- The system also includes a locking ring and an annular retainer. The locking ring is configured to engage axially between the inner and outer claw teeth to prevent the claw clutch ring from rotating within the cup-shaped portion. The annular retainer is mounted in the cup-shaped portion to lock the locking ring axially within the cup-shaped portion.

[0033] -- The cross-section of the retaining ring is wedge-shaped. The retaining ring is configured to be axially offset outward from the cup-shaped part under the action of centrifugal force during operation, and to keep the root of the impeller axially clamped through the wedge effect;

[0034] -- The cylindrical section is made of two half-shells, which are mounted and attached to the main body. The half-shells are joined at a horizontal level at a joint plane passing through the pitch axis.

[0035] -- The cylindrical part is glued to the main body;

[0036] -- At least one preloaded assembly ring is mounted around the half-shell to keep the half-shell securely against the body, the preloaded assembly ring extending about the pitch axis;

[0037] -- The lower preload assembly ring is mounted on the low cylindrical surface of the cylinder and extends around at least a portion of the free end of the body;

[0038] -- The upper preload assembly ring is mounted on the high cylindrical surface of the cylinder and extends around a portion of the spherical part of the body;

[0039] -- A claw-shaped clutch ring extends around a pitch axis and is forcibly mounted around a root support between a spherical portion and a blade at the root. The claw-shaped clutch ring includes external claw-shaped teeth configured to cooperate with the system.

[0040] -- The claw-shaped clutch ring is configured to be mounted on a tall cylindrical surface of the cylindrical portion;

[0041] -- The first guide bearing extends at least partially around the lower preload assembly ring, and the second guide bearing extends at least partially around the upper preload assembly ring.

[0042] During operation, the guide bearings withstand the mechanical forces generated by the aerodynamics and centrifugal forces applied to the blades. The lower bearing can be configured to ensure the centrifugal retention of the blades, while the upper bearing can be configured to withstand the bending moments generated by the aerodynamics and centrifugal forces. The distance between the bearings along the pitch axis creates sufficient leverage to prevent the blades from rotating at any stage of flight.

[0043] The present invention also relates to an assembly comprising the system described above and a variable pitch propeller blade, the blade comprising blades connected to a root, the root comprising a body housed in an annular cylindrical portion extending about the pitch axis of the blade.

[0044] Preferably, the body is solid (i.e., without a recessed hollow portion). Advantageously, the body includes a free end located on the opposite side of the blade, the free end being configured to mate with the control system in a form-fitting manner. Preferably, the cylinder portion is independent of the control system.

[0045] The present invention also relates to a turbine engine, particularly a turbine engine for an aircraft, the turbine engine comprising at least one system as described above.

[0046] Finally, the present invention relates to a method for installing a system as described above, wherein the method includes the following steps:

[0047] a) By shifting the blade in a direction parallel to the pitch axis, the root of the blade is inserted into the cup-shaped part of the system.

[0048] b) The free end of the root is joined to a recess in the bottom wall of the cup-shaped part to fix the cup-shaped part to the root of the impeller in terms of rotation, and

[0049] c) Engage the retaining ring, which was previously installed or present around the root of the impeller, into the cup-shaped portion, and install the ring in the cup-shaped portion and on the root of the impeller to ensure that the root is axially retained in the cup-shaped portion, and

[0050] d) Engage the at least one safety element in the hole in the bottom wall of the cup-shaped portion and the free end of the root portion.

[0051] Advantageously, during step a) and / or step b), the root of the blade is supported on the elastically deformable member and the elastically deformable member is axially compressed.

[0052] Preferably, during step c), the retaining ring is installed into the cup-shaped portion by means of a claw clutch. Attached Figure Description

[0053] Other features and advantages will become apparent from the following description of non-limiting embodiments of the present invention, with reference to the accompanying drawings, in which:

[0054] [ Figure 1 ] Figure 1 It is a schematic perspective view of the propeller blades used in aircraft turbine engines;

[0055] [ Figure 2 ] Figure 2 yes Figure 1 A magnified view of a portion of the blades, showing the root of the blades;

[0056] [ Figure 3 ] Figure 3 It has Figure 1 A schematic perspective view of a partial exploded view of the root of the blade;

[0057] [ Figure 4 ] Figure 4 yes Figure 1 A schematic perspective view of the main body of the root of the whorl blades;

[0058] [ Figure 5 ] Figure 5 yes Figure 1 Another schematic axial section view of the root of the impeller and the guide bearing, with the section plane extending along the chord of the impeller blade;

[0059] [ Figure 6 ] Figure 6 yes Figure 1 A schematic axial cross-sectional view of the root of the impeller and the guide bearing, with the cross-sectional plane extending transversely to the chord of the impeller blade.

[0060] [ Figure 7 ] Figure 7 It is along Figure 5 Another schematic cross-sectional view of line VII-VII;

[0061] [ Figure 8 ] Figure 8 yes Figure 1 A schematic axial section view of the blade root and the system used to control the pitch setting of the blade.

[0062] [ Figure 9 ] Figure 9 yes Figure 8 A schematic perspective view of the cup-shaped portion of the system;

[0063] [ Figure 10 ] Figure 10 yes Figure 8 A schematic perspective view of the claw-shaped clutch ring in the system;

[0064] [ Figure 11] Figure 11 yes Figure 8 A schematic perspective view of the locking ring component of the system;

[0065] [ Figure 12 ] Figure 12 yes Figure 8 A schematic perspective and partial axial section view of the root of the impeller and the system, showing the first installation step;

[0066] [ Figure 13 ] Figure 13 yes Figure 8 A schematic perspective and partial axial section view of the root of the impeller and the system, and the second installation step is shown;

[0067] [ Figure 14 ] Figure 14 yes Figure 8 A schematic perspective and partial axial section view of the root of the impeller and the system, and the third installation step is shown;

[0068] [ Figure 15 ] Figure 15 yes Figure 8 A schematic perspective and partial axial section view of the root of the impeller and the system, and the fourth installation step is shown;

[0069] [ Figure 16 ] Figure 16 yes Figure 8 A schematic perspective and partial axial section view of the root of the impeller and the system, and the fifth installation step is shown;

[0070] [ Figure 17 ] Figure 17 yes Figure 8 A schematic perspective and partial axial section view of the root of the impeller and the system, showing the sixth installation step, and...

[0071] [ Figure 18 ] Figure 18 yes Figure 1 A schematic axial cross-sectional view of the root of the impeller and a first embodiment of the system according to the invention for controlling the pitch setting of the impeller.

[0072] [ Figure 19 ] Figure 19 yes Figure 1 A schematic axial cross-sectional view of the root of the impeller and a second embodiment of the system according to the invention for controlling the pitch setting of the impeller, and

[0073] [ Figure 20 ] Figure 20 This is a schematic diagram of a variant embodiment of the safety element. Detailed Implementation

[0074] Figure 1 The image shows the blade 10 of a propeller for an aircraft turbine engine, which may be ducted or non-ducted.

[0075] The whorl 10 includes blades 12 connected to the root 14.

[0076] The blade 12 has an aerodynamic profile and includes an inner arc surface 12a and an outer arc surface 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 during operation.

[0077] The blade 12 has a free upper end (referred to as the tip) and a lower end connected to the root 14.

[0078] In the example shown, the blade 10 is made of composite material by an injection 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, 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 attached and mounted, for example, by gluing.

[0079] The blade 10 here includes a longon 22, which includes: a portion forming the core of the blade 12 and intended to be inserted into the preform 18 prior to resin injection, and a portion (referred to as body 24) extending from the side opposite the tip of the blade 14 to form part of the root 14.

[0080] Preferably, the spar 22 is made of a 3D woven carbon fiber reinforced epoxy organic matrix composite material, with the warp direction primarily radially oriented at the aerodynamic duct height, while the weft direction is primarily oriented along the chord of the blade. However, the spar can also be a mechanically more advantageous component of different organic matrix composite materials (thermopolymers, thermoplastics, or elastomers), reinforced with long fibers (carbon, glass, aramid, polypropylene) in different fiber arrangements (woven, spun, knitted, unidirectional).

[0081] Although not shown, the blade 12 may be hollow or solid and includes an internal cavity filled with a foam or honeycomb filler material. This filler material is mounted around the spar 22 and covered with an organic matrix composite surface to increase the blade's impact resistance.

[0082] The sheath 20 can be made of titanium or titanium alloy, stainless steel, steel, aluminum, nickel, etc. The inner arc surface 12a or even the outer arc surface 12b of the blade 12 can be covered with a polyurethane film to prevent corrosion.

[0083] The root portion 14 basically comprises two parts, namely the body 24 and the annular cylindrical portion 26, which extends around the axis A of the body 24 and the impeller.

[0084] Axis A is the elongation axis of blade 10 and blade 12, and in particular the pitch axis of the blade (i.e., the axis around which the angular position of the blade is adjusted). Axis A is also generally a radial axis, and therefore extends radially along the axis of rotation of the propeller equipped with the blade.

[0085] exist Figures 3 to 7 The specific shape of the main body 24 of the root 14 can be clearly seen in the middle.

[0086] The main body 24 basically consists of three parts:

[0087] - Free end 28, which is located on the opposite side of blade 12.

[0088] - Support 30, which is located on one side of the blade, and

[0089] - Spherical portion 32, which is located between the free end and the support.

[0090] In the example shown, the free end 28 has a roughly parallelepiped shape. Figure 7 As can be seen, this end 28 is offset from axis A to achieve detrompage or indexing, as will be explained in more detail below.

[0091] Pb is defined as a transverse plane, that is, a plane perpendicular to axis A that passes substantially through the middle of end 28 and is measured along axis A. This plane Pb is referred to as the low plane or lower plane. Figure 7 The cross-sectional shape of end 28 in the plane Pb is shown. This cross-section (referred to as the low section) has a value or surface area (e.g., the maximum value, denoted as Sb) and has a roughly rectangular shape in the example shown.

[0092] As will be described below, end portion 28 is configured to cooperate with system 34 for controlling the pitch setting of the blades.

[0093] Column 30 has a relatively complex shape and can be considered to include:

[0094] - Two lateral surfaces 30a and 30b are located on one side of the inner arc surface 12a and the outer arc surface 12b of the blade 12, respectively. The two lateral surfaces converge toward each other along axis A and in the direction of the tip of the blade 12 (see...). Figure 4 and Figure 6 ),as well as

[0095] - Two edges, namely upstream edge 30c and downstream edge 30d, which are separated from each other along axis A and along the tip of blade 12 (see...). Figure 4 and Figure 5 ).

[0096] Ph is defined as a transverse plane passing through the support 30, specifically a transverse plane passing through the lower end of the support. This plane Ph is referred to as the high plane or upper plane. In this plane, the cross-section of the support can have a non-circular shape (e.g., oval, elliptical, square, or rectangular). This cross-section (referred to as the high section) has a value or surface area (e.g., the maximum value, denoted as Sh).

[0097] The spherical portion 32 has a generally convex or dome-shaped shape, which extends about axis A.

[0098] Pm is defined as the intermediate plane passing through the spherical portion 32, specifically the intermediate plane passing through the largest cross-sectional portion of the spherical portion (denoted as Sm). This plane Pm is referred to as the average plane. In this plane, the cross-section of the spherical portion 32 may have a circular shape, although this cross-section is not restrictive.

[0099] It should be understood that plane Pm lies between planes Pb and Ph. The cross-section of the spherical portion 32 decreases from plane Pm (Sm) to plane Ph, and decreases from plane Pm to plane Pb. Therefore, it can be understood that Sm is greater than Sb and Sh. Furthermore, in the example shown, Sh is greater than Sb.

[0100] As in Figure 3 As can be seen, the cylindrical portion 26 is made of two half-shells 26a and 26b, which are mounted and attached to the main body 24. For example, one half-shell is on one side of the inner arc surface 12a of the blade, and the other half-shell is on one side of the outer arc surface 12b of the blade 12. Thus, the half-shells 26a and 26b are joined at the level of the joining plane, which passes through the axis A and extends substantially parallel to the chord of the blade 12.

[0101] Advantageously, the cylindrical portion 26 is preferably attached to the body 24 by adhesive bonding. The adhesive extends between the cylindrical portion and the body around axis A.

[0102] The barrel portion 26 is preferably made of metal (steel, titanium, or a titanium alloy such as TA6V). The adhesive is, for example, an epoxy adhesive filled with thermoplastic or elastomeric nodules or reinforced with fabric. This bonding method is particularly suitable because the contact surface area between the cavity of the barrel portion and the body, which may be a composite material, is large. The presence of adhesive bonding is advantageous because it allows for the correction of minor shape defects. Adhesive bonding also allows for the prevention of friction at the metal / composite material interface, thereby increasing the service life of the impeller.

[0103] Several possibilities are envisioned for mounting the cylinder 26 to the body 24. The first possibility is that once the two half-shells 26a, 26b of the cylinder 26 are installed, a gap is intentionally left between them to allow for proper pressure application during adhesive bonding and curing. The curing stage can be completed in an autoclave, with the entire impeller inside a vacuum bag. However, this operation can also be performed in a flattening machine. However, a disadvantage of leaving a gap between the two half-shells 26a, 26b is that the positioning of the two half-shells is more difficult to control, thus requiring rework of the outer surfaces. The second possibility is to mount one half-shell against the other around the body without any existing gaps. This strategy is possible, for example, by machining a blank that has already been cut into two parts and held together during the machining operation to ensure the geometry of the outer surfaces once the half-shells are reassembled. This allows for control over the positioning and geometry of the outer surfaces of the cylinder 26 without requiring additional machining after bonding. In any case, locating pins or stops can be considered to ensure the relative position of the cylindrical half-shell.

[0104] However, the presence of glued joint between the body and the cylinder is not mandatory, although it is highly advantageous. Alternatively, prestressed washers (or springs) can be used between the cylinder and the composite body to radially push the body against the support surface of the cylinder. When the two halves of the cylinder are mounted around the spherical portion, the geometry of the cylinder can also be used to slightly “clamp” the body. In this case, it is the deformation of the cylinder that generates the prestress. Therefore, tools must be provided to hold this position before final assembly.

[0105] As in Figure 5 and Figure 6 As can be seen, the cylindrical portion 26 covers and conforms to at least a portion of the spherical portion 32 and at least a portion of the support 30. The cylindrical portion 26 has a cross-sectional shape that is complementary to the spherical portion 32 at the level of the intermediate cross-section Sm, and a cross-sectional shape that is complementary to the support 30 at the level of the high cross-section Sh.

[0106] More specifically, in the example shown, the cylindrical portion 26 comprises three parts.

[0107] - Lower end portion 36, which has a generally annular shape (see...) Figures 5 to 7 The lower end extends at the level of the free end 28 of the root and extends around the free end of the root.

[0108] - The upper end portion 38 extends horizontally at the plane Ph and includes two lateral lips 40 applied to the sides 30a and 30b of the support 30, and

[0109] - The middle portion 42 is applied to the spherical portion 32 and closely conforms to the shape of the spherical portion.

[0110] The lip 40 is supported on the sides 30a and 30b of the support 30, which allows the root 14 of the blade to be stiffened and strengthens the resistance of the root of the blade to torsion around the pitch axis A.

[0111] Furthermore, the lips allow for energy absorption in the event of an impact to the impeller 10 (such as from a bird ingestion). Rounded corners may be present on these lips to prevent localized wear or damage to the main body.

[0112] The inner surface of the cylindrical portion 26 that contacts the body 24 serves as a support surface. Compared to a broached attachment, the support surface is maximized by utilizing the entire circumference of the blade's base. In a broached attachment, only two distinct surfaces at the blade root, located on the inner and outer arc surfaces respectively, are supported on the support surface, while the surfaces at the blade root located on the leading and trailing edges are free. Also compared to a broached attachment, the support surface has a much greater radial height, which contributes to a significant increase in its surface area. This large support surface allows for reduced contact pressure under all operating conditions.

[0113] The cylindrical portion 26 includes two cylindrical surfaces 44 and 46a for mounting preload assembly rings 48 and 50. The preload assembly rings 48 and 50 enable the half-shells 26a and 26b to be held fastened to each other and to the main body 24. The preload assembly rings 48 and 50 extend about axis A.

[0114] Surface 44 is located on the lower end 36 and is oriented radially outward relative to axis A. This surface is fitted with a pre-tightened receiving ring 48, which engages from below and is axially supported on a cylindrical support surface located at the junction of the end 36 and the intermediate portion 42 of the cylindrical portion 26.

[0115] Surface 46a is located on the intermediate portion 42 and is oriented radially outward relative to axis A. This surface is fitted with a pre-tightened receiving ring 50, which engages from above and is axially supported on a cylindrical support surface located near plane Pm.

[0116] As can be seen, surface 46a is located adjacent to cylindrical surface 46b, which is designed to receive retaining ring 52, as will be described below.

[0117] In the example shown, surfaces 44 and 46a and rings 48 and 50 have different diameters. The diameter of surface 46a is larger than the diameter of surface 44, therefore the diameter of ring 50 is larger than the diameter of ring 48.

[0118] Surfaces 46a and 46b may have the same or different diameters. For example, the diameter of surface 46b may be slightly smaller than the diameter of surface 46a. This is especially true when ring 50 is to be mounted relative to surface 46b with a predetermined radial clearance.

[0119] from Figure 5 and Figure 6 As can be seen, ring 50 is located between plane Ph and plane Pm, and ring 48 is located between plane Pm and plane Ps.

[0120] Figure 5 and Figure 6 The positions of rings 48, 50 and planes Pm, Ph, Ps relative to rolling bearings 54, 56, which extend about axis A and root 14, are also shown.

[0121] There are two bearings 54 and 56 here, namely the lower bearing 54 and the upper bearing.

[0122] Bearings 54 and 56 are ball bearings. In the example shown, the bearings have different diameters, and the balls in the bearings also have different diameters.

[0123] Bearing 54 extends substantially between plane Pm and plane Pb, and thus extends around the lower portion of ball 32. The bearing also extends around ring 48. The diameter of bearing 54 is smaller than the diameter of bearing 56, and the diameter of the balls in bearing 54 is larger than the diameter of the balls in bearing 56.

[0124] Bearing 54 is also an angular contact bearing. In the example shown, the bearing support point or surface of the ball on the raceway of the ball rings 54a, 54b is located on a truncated conical surface S1 that extends along axis A, and the maximum diameter of the truncated conical surface is located on one side of the tip of the impeller.

[0125] Bearing 56 extends substantially between planes Pm and Ph, and thus extends around the upper portion of spherical portion 32. The bearing also extends around ring 50. Bearing 56 is also in angular contact. In the example shown, the bearing support points or surfaces on the raceways of the ball rings 56a, 56b are located on a truncated conical surface S2, which extends along axis A, and the maximum diameter of this truncated conical surface is located on one side of the free end of the root of the impeller.

[0126] The intermediate section, located between the two bearings 54 and 56, is highly advantageous in terms of overall radial dimensions because a portion of the support surface height between the intermediate and high sections lies within the cup-shaped portion 58, unlike the broached attachments integrated into the pivot in the prior art. This helps reduce the overall radial dimensions of the control system 34.

[0127] Figures 8 to 17 Examples of embodiments of the system are shown, and in particular, examples of embodiments of the retaining ring 52 are shown.

[0128] System 34 includes a cup-shaped portion 58, which includes an annular wall 58a extending around axis A. The wall 58a includes a lower axial end closed by a bottom wall 58b and an open upper axial end, the upper axial end being configured such that the root 14 of the impeller can be mounted within the cup-shaped portion. Here, axis A of the cup-shaped portion is considered to be the axis of rotation of the impeller, corresponding to the axis of rotation for changing the pitch setting of the impeller, and is substantially radial relative to the rotation of the propeller.

[0129] The bottom wall 58b is configured to engage with the free end of the root 14 in a shape-fitting manner, and thus with the end 28 of the body 24, such that the cup-shaped portion is fixed to the root in terms of rotation about the axis.

[0130] In this context, it should be understood that the bottom wall 58b includes a recess 60 having a non-circular cross-section, particularly a rectangular cross-section, and is configured to receive the end 28. Figure 8 ). For example in Figure 5 As can be seen, the recess 60 is eccentric relative to axis A in a manner similar to that of end portion 28 (see [reference]). Figure 7 When the root is inserted and installed into the cup-shaped portion 58, this eccentricity enables indexing and error prevention, while the end 28 has only one possible engagement position in the recess 60.

[0131] The recess 60 is located on the upper or inner surface of the bottom wall 58b of the cup-shaped portion 58, so the recess is located inside the cup-shaped portion and is oriented toward the root.

[0132] System 34 generates torque at the blade root that counteracts the torsional moment generated by aerodynamics and centrifugal force. Like the rest of the body 24 of the root 14, the end 28 of the root 14 can be enclosed in the cylindrical portion 26. In this case, the end of the root will also have a non-circular shape to constrain rotation of that end. However, it is advantageous, as described above, to have this end of the body protrude from the cylindrical portion to directly constrain rotation of the body. This provides a more direct force path, with the torsional moment applied directly to the body. The dimensions of the low section are strictly smaller than the maximum dimensions of the intermediate section to limit the overall circumferential dimension at that height. Therefore, the overall circumferential dimension of the cylindrical portion at this height is also smaller than the overall circumferential dimension at the level of the intermediate section. This allows for a reduction in the diameter of the lower bearing located below the intermediate section. Therefore, the blade root can be integrated radially downwards, which significantly reduces the theoretical hub ratio associated with root integration. Those skilled in the art know that a low hub ratio improves engine performance, particularly resulting in a more compact and therefore lighter engine. This last point is a very important advantage of this technical solution compared to competitors, who have traditionally proposed cylindrical sections with a cylindrical external shape.

[0133] The bottom wall 58b includes a lower or outer surface located on the opposite side of the root 14 and includes a cylindrical extension 62 extending along axis A and including an external thread or external straight spline 64 for rotatably connecting the system to a pitch changing mechanism (not shown), which is common to the propeller blades 10 and the different systems 34.

[0134] An elastically deformable member 66 (such as a helical spring) extends about axis A and is mounted within the cup-shaped portion 58. The member 66 is axially supported on the upper surface of the bottom wall 58b, located at the outer periphery of the surface in the illustrated example, and is configured to axially bias the root of the blade toward the outside of the cup-shaped portion, i.e., axially biased toward the tip of the blade.

[0135] Component 66 is supported on the cylindrical support surface 68 of the cylindrical portion 26. In the example shown, component 66 is centered by engaging the upper end of the component to and around the cylindrical edge 70 of the cylindrical portion, and by engaging the lower end of the component to and around the cylindrical edge 72 of the cup-shaped portion, which is located at the outer periphery of the bottom wall 58b.

[0136] Component 66 extends here around the pre-tightening assembly ring 48.

[0137] As in Figure 8As can be seen, the cup-shaped portion 58 is designed to support bearings 54 and 56, which ensure that the cup-shaped portion is centered and guided about axis A relative to the housing 74 or the fixed structure of the turbine engine. Therefore, the cup-shaped portion 58 serves as a pivot for the impeller relative to the housing 74.

[0138] Bearings 54 and 56 may be part of a control system. In particular, at least one of the guide bearings may have an inner ring integrated into the cup-shaped portion.

[0139] The same applies to the lower bearing 54, which has an inner ring 54a integrated into the cup-shaped portion 58. In effect, this means that the cup-shaped portion includes a raceway 54aa at its outer periphery, on which the balls of the bearing 54 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-shaped portion and the lower end of the wall 58a. The outer ring 54b of the bearing 54 is attached to the housing 74, for example, by preload assembly. Furthermore, advantageously, the cup-shaped portion 58 is designed to apply prestress to the bearing 54.

[0140] The outer ring 56b of the bearing 56 is attached to the housing 74, for example, by preload assembly. The inner ring 56a of the bearing engages with the free upper end of the cup-shaped portion 58 and the free upper end of the wall 58a, and engages around the free upper end of the cup-shaped portion and the free upper end of the wall. This end of the wall 58a includes an outer cylindrical surface 76 for mounting the inner ring 56a and external threads for tightening a nut 78, which is intended to be axially supported on the inner ring 56a to keep the inner ring axially fastened against the outer cylindrical shoulder 80 of the cup-shaped portion 58.

[0141] The cup-shaped portion wall 58a also includes a device configured to cooperate with the aforementioned retaining ring 52 at its inner periphery.

[0142] The retaining ring 52 extends about axis A and is configured to be mounted around the root 14. The retaining ring 52 is configured to be mounted inside the cup-shaped portion and to engage with the annular wall 58a of the root 14 and the cup-shaped portion 58, respectively, to ensure that the root is axially retained in the cup-shaped portion.

[0143] exist Figures 8 to 17 In an exemplary embodiment, the retaining ring 52 is a claw-shaped clutch ring, which includes an outer claw-shaped tooth 84 configured to engage with the complementary inner claw-shaped tooth 82 of the annular wall 58a of the cup-shaped portion 58.

[0144] exist Figure 9 The teeth 82 of the cup-shaped portion 58 can be clearly seen. These teeth are evenly spaced around axis A. In the non-limiting example shown, there are six teeth. For example, each of these teeth extends at an angle between approximately 20° and 30° around axis A.

[0145] Each tooth in tooth 82 includes a groove 86 at its inner periphery, the groove being circumferentially oriented relative to axis A. The groove 86 of tooth 82 forms a discontinuous valley around axis A.

[0146] exist Figure 10 The claw-shaped clutch ring can be clearly seen. The teeth 84 of the claw-shaped clutch ring are regularly spaced around axis A. In the non-limiting example shown, there are six teeth. For example, each of these teeth extends at an angle between approximately 20° and 30° around axis A.

[0147] Tooth 84 is complementary to tooth 82 and is configured to engage with these teeth via a claw clutch. The installation method of the claw clutch is well-known in the aerospace field, and will be achieved through... Figures 12 to 17 This demonstrates the installation method.

[0148] The ring 52 includes an inner cylindrical surface 52a, which is designed to engage with the aforementioned surface 76 of the cup-shaped portion 58 by sliding.

[0149] Ring 52 includes a second set of teeth 88 that extend axially upward on one side of the tip of blade 10. These teeth 88 are also regularly spaced around axis A. In the example shown, there are six teeth 88. These teeth can be staggered relative to teeth 84, i.e., the circumferential space between teeth 88 and teeth 84 is axially aligned. As a non-limiting example, each tooth 88 extends at an angle between approximately 10° and 20° around axis A.

[0150] Each tooth in tooth 88 includes a groove 90 at its inner periphery, which is circumferentially oriented relative to axis A. The groove 90 of tooth 88 forms a discontinuous valley around axis A.

[0151] Figure 11 A locking ring 92 is shown, which is configured to engage axially between claw teeth 82, 84 to prevent rotation of ring 52 within cup portion 58.

[0152] The annular component 92 includes slides 94 (in the non-limiting example shown, the number of slides is six), which are designed to engage in the inter-tooth space extending between the teeth 82 and 84. Therefore, it should be understood that these slides 94 have a shape complementary to the shape of these spaces and are regularly spaced around axis A.

[0153] In the example shown, slides 94 are secured to each other by bridging members 96 extending circumferentially between slides 94. There are five bridging members 96, each extending between two adjacent slides 94. Two slides in the slides 94 are intentionally not connected by bridging members, leaving the annular member 92 open. This simplifies assembly when the annular member is installed in system 34 by moving the slides away from or toward each other.

[0154] Each slide in slide 94 includes a groove 98 at its inner periphery, which is circumferentially oriented relative to axis A. The groove 98 in slide 94 forms a discontinuous valley around axis A.

[0155] The system also includes a ring retainer 100, which is only used when... Figure 17 As can be seen in the text.

[0156] A retaining ring 100 is installed in the cup-shaped portion 58 to axially retain the locking annular member 92 within the cup-shaped portion 58. The retaining ring 100 can also be separated or opened to facilitate its installation, and when the grooves 86, 98 are all located in the same plane perpendicular to axis A and arranged circumferentially relative to each other to form a complete valley around axis A, the retaining ring is intended to engage in the groove 86 of the tooth 82 of the cup-shaped portion and the groove 98 of the slide 94 of the annular member 92 (see [link to relevant documentation]). Figure 16 and Figure 17 ).

[0157] Now refer to Figures 12 to 17 , Figures 12 to 17 It shows the installation of by Figure 1 The blade 10 shown and Figure 8 The method for forming components of system 34 shown.

[0158] exist Figure 12 In the first step shown, the root 14 of the impeller 10 is engaged in the cup-shaped portion 58 of the system 34 by axial translation along axis A until the end 28 of the root body 24 is engaged in the recess 60 of the cup-shaped portion 58. As can be seen in the figure, the pre-tightening assembly ring has been forcibly installed around the support 30 of the root body. Although not shown in the figure, when the root 14 is inserted into the cup-shaped portion 58, member 66 ( Figure 8 () is compressed.

[0159] exist Figure 12 and Figure 13 In the second step shown, the pre-tightening assembly ring is positioned at an angle around axis A, such that the space between the ring teeth 84 and the teeth 82 of the cup-shaped portion is aligned. Then, the ring 52 is axially translated within the cup-shaped portion 58 until the ring 52 engages on the surface 46b of the cylindrical portion 26, and the teeth 84 are positioned exactly below the teeth 82, as shown. Figure 13As shown. The groove 90 provided on the teeth can be used to clamp the ring 52 with a suitable tool.

[0160] exist Figure 13 and Figure 14 In the third step shown, ring 52 is rotated about axis A, such that the teeth 82, 84 are axially aligned with each other. This angular displacement is approximately 25° to 30° due to the angular extension of the teeth in the example shown. Teeth 88 can be used to clamp ring 52 and rotate it using the aforementioned tool. Member 66 (not shown) offsets the root axially outward from the cup-shaped portion, such that teeth 84 are axially supported on teeth 82. Thus, the root is axially held within the cup-shaped portion and system 34. During operation, centrifugal forces applied to the impeller are transmitted to the cup-shaped portion 58 via teeth 82, 84, and these forces are directly borne by bearing 54, whose inner ring 54a is integrated into the cup-shaped portion 58.

[0161] exist Figure 15 and Figure 16 In the fourth step shown, the annular member 92 is positioned at an angle about axis A such that the slide 94 of the annular member is aligned with the space between the teeth 82, 84. Then, the annular member 92 is axially translated within the cup-shaped portion 58 until the slide 94 engages in these spaces. The bridging member 96 can then be supported on the teeth 84 of the ring 52. Therefore, the annular member 92 prevents any rotation of the ring 52 within the cup-shaped portion 58.

[0162] exist Figure 17 In the final step shown, the retaining ring 100 engages in the circumferentially aligned grooves 86 and 98. The retaining ring 100 prevents accidental disassembly of the annular member 92.

[0163] It should be understood that the blade removal is performed by reversing the aforementioned steps. It should also be understood that one of the basic steps in the installation and removal of the root is the retaining ring 52. This ring 52 can be manipulated from outside the turbine engine, which is particularly advantageous during maintenance operations. The blade can be removed from the propeller by removing and discarding a minimal number of components.

[0164] Now refer to Figures 18 to 19 , Figures 18 to 19 Two embodiments of the control system 34 according to the present invention are shown.

[0165] Each of these systems differs from the systems described above because each of these systems is equipped with a safety feature known as "fail-safe".

[0166] Therefore, the above text about Figures 1 to 17 The description applies to Figure 18 and Figure 19 The control system.

[0167] exist Figure 18 and Figure 19 In each of the systems shown, at least one safety element 110 ensures the retention of the root 14 and the cup-shaped portion 58. Fail-safety can be ensured by a single such safety element 110 or by multiple (e.g., two or three) adjacent and parallel safety elements. The safety element 110 enables the impeller 10 to be prevented from being released in the event of a failure of the retaining ring 52.

[0168] In the illustrated embodiment, the safety element 110 has a generally elongated shape and extends laterally relative to axis A. The safety element 110 passes through alignment holes 112, 114 in the bottom wall 58b of the cup-shaped portion 58 and the free end 28 of the root portion 14. The free end 28 is formed by an integral protrusion of the body 24, provided that the cylindrical portion 26 is axially rearward from this free end.

[0169] As shown in the example, safety element 110 may be a bolt including a screw and nut 116.

[0170] The screw includes a threaded shank 118 passing through holes 112 and 114 and a head 120 that abuts against a lateral face 122 of the bottom wall 58b. A nut 116 is tightened onto the threaded shank 118 and is supported on the opposite lateral face 124 of the bottom wall 58b. Faces 122 and 124 are parallel to each other and parallel to axis A. For example, the diameter of the threaded shank 118 is between 1.27 mm (1 / 2 inch) and 0.95 mm (3 / 8 inch).

[0171] The safety element 110 passes through the hole 114 of the free end 28 of the root 14 with a predetermined gap J1, and through the hole 112 of the bottom wall 58b of the cup-shaped portion 58 with another predetermined gap J2.

[0172] exist Figure 18 In the illustrated embodiment, these gaps J1 and J2 are substantially the same.

[0173] exist Figure 19 In the alternative embodiment shown, the cylindrical portion 26 includes an axial extension 26za surrounding a protrusion at the free end 28 of the root portion 14, and the axial extension includes a hole 126 aligned with a hole 114 in the protrusion and a hole 112 in the bottom wall 58b. A safety element 110 passes through holes 112, 114, and 126.

[0174] exist Figure 18 In this case, the safety element 110 passes through the lower end of the blade and enables the blade 10 to be held by introducing a secondary force path on the cup-shaped portion 58 and thus on the inner ring of the bearing 54 integrated into the cup-shaped portion.

[0175] exist Figure 19 In this arrangement, the gap J3 between the safety element 110 and the hole 126 of the cylinder 28 is smaller than the gap J1' between the safety element 110 and the hole 114 of the protrusion, and preferably the same as the gap J2 between the safety element 110 and the hole 112 of the bottom wall 58b of the cup-shaped portion 58. This allows the safety element 110 to primarily engage with the cylinder 28 when holding the blade, rather than with the protrusion of the root 14. The cylinder 28 is made of a (metallic) material that is harder and more resistant to support constraints than the (composite) material of the root. Therefore, in the event of a problem, the engagement of the cylinder 26 with the safety element 110 will ensure the retention of the root 14 of the blade. The protrusion of the root 14 will not be biased, and therefore there is no risk of damage in the event of a failure of the retaining ring 52. The cylinder 26 will be able to dissipate energy through plastic deformation and release the main body of the composite root.

[0176] exist Figure 20 In the variant embodiment shown, the safety element 110' is a stud comprising a cylindrical body 128 designed to pass through the aforementioned hole. The body 128 includes a longitudinal end connected to a head 130 and an opposing longitudinal end having a transverse hole 132 for receiving a brake line type or similar lock 134. For example, the diameter of the body 128 is between 1.27 mm (1 / 2 inch) and 0.95 mm (3 / 8 inch).

[0177] The present invention also proposes a method for installing system 34, the method comprising the following steps:

[0178] a) By shifting the impeller 10 in a direction parallel to the pitch axis A, the root 14 of the impeller 10 is inserted into the cup-shaped portion 58 of the system 34.

[0179] b) The free end 28 of the root 14 is engaged in the recess 60 of the bottom wall 58b of the cup-shaped portion 58 to fix the cup-shaped portion 58 to the root 14 of the impeller 10 in terms of rotation.

[0180] c) Engage the retaining ring 52, which was previously mounted or present around the root 14 of the impeller 10, into the cup-shaped portion 58, and install the ring 52 in the cup-shaped portion 58 and onto the root 14 of the impeller 10 to ensure that the root 14 is axially retained in the cup-shaped portion 58, and

[0181] d) Engage one or more safety elements in holes in the bottom wall 58b of the cup-shaped portion 58 and the free end 28 of the root 14.

[0182] The introduction of the safety element affects the installation sequence of the blade 10 within its housing. Initially, the blade 10 is installed only from the outside. The installation of the safety element 10 requires an additional passage within the cavity formed by the housing 74 to access the lower portion of the blade. The fairing of this cavity can be designed to accommodate this passage.

[0183] Other variant embodiments, not shown, are possible and include:

[0184] • The semi-shells 26a and 26b of the cylindrical part 26 can be installed onto the main body 24 by bolting, riveting, welding, etc.

[0185] • The adhesive used to connect the cylinder 26 to the body 24 can be an epoxy adhesive, but it can also be an elastomer or thermoplastic adhesive. A non-stick film can also be used to allow relative movement while limiting wear caused by friction;

[0186] • The issue remains about the tube / body interface. Among the proposed technical solutions (gluing, applying prestress through washers or springs, applying prestress through the geometry of the tube), it is also possible to combine multiple technical solutions that can be combined independently of the presence of a gap between the two parts of the tube.

[0187] • Although less advantageous, the radial position of the bearing that ensures the centrifugal retention of the blades can be opposite to the radial position of the bearing that withstands the bending moment generated by aerodynamics and centrifugal force.

Claims

1. A system (34) for controlling the pitch setting of the propeller blades (10) of an aircraft turbine engine, characterized in that, The system includes: - Propeller blade (10), the propeller blade including blades (12) connected to the root (14). - A cup-shaped portion (58) comprising an annular wall (58a) extending around the pitch axis (A) of the propeller blade (10), the annular wall (58a) comprising a lower axial end closed by a bottom wall (58b) and an open upper axial end, the upper axial end being configured such that the root (14) of the propeller blade (10) can be mounted inside the cup-shaped portion (58), the bottom wall (58b) comprising a recess (60) having a non-circular cross-section and being configured to receive a free end (28) of a complementary shape of the root (14), such that the cup-shaped portion (58) is rotationally secured to the root (14) around the pitch axis (A), and - A retaining ring (52) extending about the pitch axis (A) and mounted around the root (14) is installed within the cup-shaped portion (58) and engages with the annular wall (58a) of both the root (14) and the cup-shaped portion (58) to ensure axial retention of the root (14) within the cup-shaped portion (58). The system (34) further includes at least one safety element (110, 110') that ensures the retention of the root (14) and the cup-shaped portion (58), the at least one safety element (110, 110') having a generally elongated shape and extending transversely to the pitch axis (A), the at least one safety element (110, 110') passing through alignment holes (112, 114, 126) in the bottom wall (58b) of the cup-shaped portion (58) and in the free end (28) of the root (14).

2. The system (34) according to claim 1, wherein, The at least one safety element is a bolt comprising a screw and a nut (116), the screw comprising a threaded rod (118) passing through the alignment holes (112, 114, 126) and a head (120) applied against a side surface (122) of the bottom wall (58b), the nut (116) being tightened onto the threaded rod (118) and supported on the opposite side surface (124) of the bottom wall (58b).

3. The system (34) according to claim 1, wherein, The at least one safety element is a stud comprising a cylindrical body (128) that passes through the alignment holes (112, 114, 126).

4. The system (34) according to any one of claims 1 to 3, wherein, The at least one safety element (110, 110') passes through the alignment hole of the free end (28) of the root (14) with a predetermined first gap (J1, J1').

5. The system (34) according to any one of claims 1 to 3, wherein, The at least one safety element passes through the alignment hole of the bottom wall (58b) of the cup-shaped portion (58) with a predetermined second gap (J2).

6. The system (34) according to claim 4, wherein, The at least one safety element passes through the alignment hole of the bottom wall (58b) of the cup-shaped portion (58) with a predetermined second gap (J2), the first gap and the second gap (J2) being the same.

7. The system (34) according to any one of claims 1 to 3, wherein, The root (14) of the propeller blade (10) includes a body (24) housed in an annular cylindrical portion (26) extending about the pitch axis (A) and at least partially housed within the cup-shaped portion (58). The free end (28) of the root (14) is formed by a protrusion of the body (24) and an axial extension (26za) of the annular cylindrical portion (26), the protrusion of the body and the axial extension of the annular cylindrical portion including alignment holes for allowing the at least one safety element (110, 110') to pass through.

8. The system (34) according to claim 7, wherein, The at least one safety element (110, 110') passes through the alignment hole of the free end (28) of the root (14) with a predetermined first gap (J1, J1'), the at least one safety element passes through the alignment hole of the bottom wall (58b) of the cup-shaped portion (58) with a predetermined second gap (J2), and the third gap (J3) between the at least one safety element (110, 110') and the alignment hole of the annular cylindrical portion (26) is smaller than the first gap between the at least one safety element (110, 110') and the alignment hole of the protrusion.

9. The system (34) according to claim 8, wherein, The third gap (J3) between the at least one safety element (110, 110') and the alignment hole of the annular cylindrical portion (26) is the same as the second gap (J2) between the at least one safety element (110, 110') and the alignment hole of the bottom wall (58b) of the cup-shaped portion (58).

10. An assembly comprising a system (34) according to any one of claims 1 to 9 and a variable pitch propeller blade (10), the propeller blade (10) comprising a blade (12) connected to a root (14), the root (14) comprising a body (24) housed in an annular cylindrical portion (26) extending about a pitch axis (A) of the propeller blade.

11. A turbine engine comprising at least one system (34) according to any one of claims 1 to 9.

12. The turbine engine according to claim 11, wherein, The turbine engine is a turbine engine used in aircraft.

13. A method for installing the system (34) according to any one of claims 1 to 9, wherein, The method includes the following steps: a) By shifting the propeller blade (10) in a direction parallel to the pitch axis (A), the root (14) of the propeller blade (10) is inserted into the cup-shaped portion (58) of the system (34). b) Engage the free end (28) of the root (14) into the recess (60) of the bottom wall (58b) of the cup-shaped portion (58) to fix the cup-shaped portion (58) to the root (14) of the propeller blade (10) in terms of rotation. c) Engage the retaining ring (52) previously mounted or present around the root (14) of the propeller blade (10) into the cup-shaped portion (58), and mount the retaining ring (52) in the cup-shaped portion (58) and onto the root (14) of the propeller blade (10) to ensure that the root (14) is axially retained in the cup-shaped portion (58), and d) Engage the at least one safety element (110, 110') in the alignment hole in the bottom wall (58b) of the cup-shaped portion (58) and the free end (28) of the root (14).

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