TOGETHER FOR A DEVICE FOR FLAGING VARIABLE PITCHING BLADES AND ITS PROCESS OF IMPLEMENTATION

Abstract

The present invention relates to an assembly (100) for a variable-pitch feathering device for the blades of an aircraft turbomachine propeller (1), the assembly (100) comprising: - an annular housing (120) extending around an axis (A) and having a first annular wall (122) extending perpendicularly to said axis (A), and - an annular row of yokes (140) distributed around the axis (A) and supported by said first annular wall (122), each yoke (140) being formed in one piece and having two bearing supports (142, 144) parallel to each other and to a plane passing through said axis (A), in which the annular housing (120) and the annular row of yokes (140) are monolithic. Figure 5

Description

Title of the invention: ASSEMBLY FOR A VARIABLE-PITCH BLADE FEATHERING DEVICE AND ITS PRODUCTION PROCESS Technical field

[0001] The present invention relates to the field of aircraft turbomachines and in particular to the propulsion propellers of these turbomachines which comprise variable-pitch blades with a device for feathering the variable-pitch blades.

[0002] In particular, the present invention relates to an assembly for a device for feathering the variable-pitch blades of a turbomachine propeller, and its method of production. The present invention also relates to a propeller module for an aircraft turbomachine comprising this assembly for a feathering device and the corresponding turbomachine. Technical background

[0003] A propeller for an aircraft turbomachine can be shrouded ([Fig. 1]), as is the case for a fan for example, or unshrouded ([Fig.2]) as is the case for an open-rotor type architecture for example.

[0004] A propeller comprises blades which may be of variable pitch. Each variable pitch blade comprises a blade connected to a root. The blade blades (or also called propeller blades in the remainder of the application) may also be of variable pitch. The turbomachine then comprises a mechanism for modifying the pitch angle of the propeller blades in order to adapt the thrust generated by the propeller according to the different phases of flight. The angular pitch of the blades also makes it possible to optimize the efficiency of the propeller according to the speed of the aircraft and to optimize the pumping margin of the turbomachine to reduce its fuel consumption in the different phases of flight.

[0005] As a reminder, the pitch angle of a propeller blade corresponds to the angle, in a longitudinal plane perpendicular to the axis of rotation of the propeller blade, between the chord of the blade and the plane of rotation of the fan or the engine of the turbomachine. The variable-pitch blades can occupy a so-called reverse thrust position (known by the English term "reverse") in which they make it possible to generate counter-thrust so as to participate in slowing down the aircraft and a feathering position in which, in the event of failure or breakdown, they make it possible to limit their aerodynamic resistance and / or drag. The consequences of this drag can be of the order of flight safety in the event of loss of control of the aircraft if the drift of the latter is not dimensioned for, and can be of the performance for the possible duration of the diversion flight on a single engine.

[0006] Multiple devices have been devised for varying the pitch of propeller blades, which generally involve rotating the blade about its main axis (corresponding to a pitch axis) by means of a control device located radially inside the blade roots. This control device comprises, for example, an actuator which can be connected to the blade roots by connecting rods and / or a linkage.

[0007] One of the functions of the blade pitch control device is to bring the blades into the predetermined position, called the "flag position" in the event of a failure of this pitch device. Feathering in particular makes it possible to minimize aerodynamic drag.

[0008] Conventionally, the feathering is achieved by a variable-pitch blade feathering device. This feathering device is typically placed radially between the blade pitch control device and the propeller blade pitch axes.

[0009] With reference to Figures 1 and 2, this feathering device 12 comprises a lever 13 and a weight 14 secured to a first end 13a of the lever 13. This weight forms a counterweight whose inertia, much greater than that of the propeller blades, must guarantee the return of the latter to the previously defined flag position. A weight 14 is generally associated with each of the propeller blades 40.

[0010] The feathering device 12 further comprises an assembly 100 allowing the components of the feathering device 10 to be connected to the control device 12 and the propeller blades 40. For this purpose, the assembly 100 comprises an annular casing 120 extending around an axis A and an annular row of yokes 140 distributed around the axis A. Each yoke 140 comprises two supports 142, 144, such as ball bearing supports. Each yoke 140 is fixed to a first annular wall 122 of the casing 120 by a bolted connection.

[0011] [Fig. 3] illustrates the bolted connection by fixing screws VI and centering bolts V2. For this, the two bearing supports 142, 144 of each of the yokes 140 are connected to each other by a partition 146. The partition 146 includes holes 149 for fixing the screws VI and bolts V2. The connection by fixing screws V2 makes it possible to ensure a fixed mechanical connection so that the yokes do not become detached from the casing during operation. The connection by centering bolts V2 makes it possible to position and center precisely with a clearance allowing the yokes 140 to be placed in a tangential position on the casing 120.

[0012] In [Fig.2], this partition 146 also comprises a bearing face 147 on the first annular wall 122 of the casing, and an axial extension 145 engaged in a through opening 121 of the first annular wall 122. The connection by this pro axial length 145 ensures precise centering with a clearance allowing the axial and radial positioning of the yokes 140 on the casing 120.

[0013] The blade feathering device 12 also comprises a connecting rod 15 connected to one of the yokes 140 and a connecting rod 16 which has a first axial end 16a connected to the connecting rod 15 and a second axial end 16b connected to the blade pitch control device 10.

[0014] The bolted connection between the annular casing and each of the yokes can have several disadvantages, such as an increase in mechanical stresses during operation and an addition of parts (bolts) and bulk compared to the large diameters of the components of the turbomachine. Indeed, the assembly of [Fig.l] requires additional connection interfaces (such as bearing faces 147, axial extensions 145, bores 149 and through openings 121) and parts (such as screws, nuts, bolts, etc.) which increase the mass and can make its assembly in the turbomachine complex. The addition of these connection and centering interfaces can also increase, on the one hand, the stresses locally and impact the mechanical strength of the assembly during operation, and on the other hand, the size of the parts to weigh down and bulk up the assembly and the feathering device.

[0015] In this context, it is interesting to overcome the drawbacks of the prior art, by proposing an assembly for a variable-pitch blade feathering device with a simple and reliable connection between the yokes and the annular casing. Presentation of the invention

[0016] The present invention provides a simple, effective and economical solution to at least some of the aforementioned problems.

[0017] The invention proposes an assembly for a variable-pitch blade feathering device for an aircraft turbomachine propeller, the assembly comprising: - an annular casing which extends around an axis A and which has a first annular wall extending perpendicular to said axis A, and - an annular row of yokes which are distributed around the axis A and which are carried by said first wall, each of the yokes being formed from a single piece and comprising two bearing supports parallel to each other and to a plane passing through said axis A.

[0018] According to the invention, the casing and the annular row of yokes are in one piece.

[0019] The single-piece connection of the invention generally makes it possible to make the assembly robust and with a reduced mass compared to the bolted connection of the prior art. Indeed, the single-piece connection (for example by welding such as by linear friction) is durable, solid and difficult to damage in operation. This improves therefore significantly the mechanical strength of this assembly for the feathering device. Furthermore, the assembly according to the invention makes it possible to reduce the number of additional parts (such as screws, nuts, bolts, connecting interfaces on the yokes, etc.) to produce a less massive and space-saving assembly.

[0020] Finally, the present solution also makes it possible to reduce costs, particularly in terms of material (since the mass of the assembly is reduced) and the time required to produce this assembly.

[0021] In the present application, two parts or parts "formed from a single piece" or "monoblock" means that these two parts or parts are physically connected to each other and cannot be separated without damaging them.

[0022] It will be noted that the yokes and the annular casing are formed from a single piece but may not necessarily be of the same material. In particular, each of the yokes formed from a single piece may be made of titanium (such as the titanium alloy Ta6V). The annular casing may be made of titanium or aluminum to allow for additional weight savings.

[0023] The assembly according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in comparison with one another:

[0024] - each of the yokes is connected to the first annular wall by a veil which has a general shape elongated in the radial direction;

[0025] - said veil comprises a first portion located on the side of the first wall annular and formed by a first projection of this first annular wall, and a second portion located on the side of each of the yokes and formed by a second projection of this yoke;

[0026] - the number of first projections is equal to the number of second projections and screeds;

[0027] - the first and second projections have radial dimensions H^s, HM8 which re have at least 50% and preferably at least 70% of an axial dimension L122 of the first annular wall;

[0028] - the bearing supports of each of the yokes are connected to each other by a partition which extends parallel to and opposite the first annular wall and on which the second projection of this yoke is formed;

[0029] - the annular casing is made of a first material, for example aluminum, different from a second material, for example titanium, of the screeds.

[0030] The present invention also relates to a propeller module for an aircraft turbomachine, comprising: - a propeller mobile in rotation around a longitudinal axis X and comprising a plurality of variable-pitch blades, each blade comprising a pivotally mounted blade along a setting axis D perpendicular to the longitudinal axis X, - a blade pitch control device, and - a device for feathering the blades, in particular in the event of failure of said control device, comprising: - at least one lever having a first end and a second end opposite this first end, and - a weight secured to the first end of the lever, said weight being capable, under the centrifugal effect, of being moved into a position in which the blades are in a flag position.

[0031] The propeller module comprises at least one assembly according to one of the features of the invention, in which one of the two bearing supports of each of the yokes is connected to the second end of the lever, and the annular casing is configured to be connected to each variable-pitch vane blade by a second annular wall.

[0032] The blade feathering device may further include: - a connecting rod connected to the other of the two bearing supports of each of the yokes, and - a connecting rod which has a first axial end connected to the connecting rod and a second axial end opposite the first axial end and connected to the blade pitch control device.

[0033] The present invention also relates to an aircraft turbomachine comprising a propeller module according to the invention, and a gas generator intended to drive the propeller.

[0034] The turbomachine can be a turbojet or a turboprop.

[0035] The present invention also relates to a method for producing an assembly according to one of the features of the invention. The method comprises the steps of: (a) producing, on the one hand, the annular casing, and on the other hand, the yokes; (b) position one of the cleats opposite the annular housing; (c) to weld the yoke to the annular housing in a single piece; and (d) repeat steps (b) and (c) for all the screeds in the assembly.

[0036] The production method according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in comparison with one another:

[0037] - the welding of step (c) is carried out by linear friction;

[0038] - the process further comprises, before step (b), a step (i) of preparation of surface of the yokes and / or the annular casing;

[0039] - the method comprises, after step (c), a step (ii) of machining a bead of weld formed at the connection between the yoke and the annular casing in step (c). Description of figures

[0040] The invention will be better understood and other details, features and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

[0041] [Fig.l] is a partial schematic view in axial section of a device for feathering variable-pitch blades of an aircraft turbomachine according to the prior art;

[0042] [Fig.2] is a partial schematic perspective view of an assembly comprising yokes and an annular casing for the feathering device of [Fig.l];

[0043] [Fig. 3] is an enlarged schematic view of a bolted connection of the assembly of Figures 1 and 2;

[0044] [Fig.4] is a schematic half-view in axial section of a propeller module of an aircraft turbomachine according to the invention;

[0045] [Fig.5] is a partial schematic perspective view of an assembly for a feathering device according to one embodiment of the invention;

[0046] [Fig.6] schematically represents in blocks the steps of a method for producing the whole of [Fig.5].

[0047] Elements having the same functions in different implementations have the same references in the figures. Detailed description

[0048] Figures 1 to 3 have been described in the technical background of the present application and illustrate an assembly for a variable pitch blade feathering device according to the prior art.

[0049] Conventionally, a turbomachine 1 comprises a gas generator G (or engine) upstream of which is mounted a propeller module S. The gas generator G of the turbomachine 1 may comprise, from upstream to downstream, a low pressure compressor, a high pressure compressor, an annular combustion chamber, a high pressure turbine, a low pressure turbine and an exhaust nozzle.

[0050] By convention, in the description below, the terms “longitudinal” and “axial” qualify the orientation of structural elements extending in the direction of a longitudinal axis. This axis can be confused with an axis of rotation of a rotor of a turbomachine. The term “radial” qualifies an orientation of structural elements extending in a direction perpendicular to the axis. The terms “inner” and “outer”, and “internal” and “external” are used with reference to a positioning relative to the axis. Thus, a structural element extending along the axis has an inner face facing the axis and an outer surface, opposite its inner surface. The terms “upstream” and “downstream” are defined with respect to the direction of circulation of the gases in the propeller module (or the turbomachine).

[0051] Generally speaking and in the remainder of the description, the term “propeller module” is used to designate indifferently a fan or a propeller, the blades of the fan or propeller which may be shrouded (for example for the bypass turbojets of [Fig.4]) or unshrouded (for example for turboprops and not shown in the figures).

[0052] The turbomachine 1 is intended to be mounted on an aircraft.

[0053] More particularly, [Fig.l] schematically illustrates a double-flow turbomachine 1 extending along a longitudinal axis X. The turbomachine 1 therefore comprises a module with a shrouded propeller S. However, the invention can be applied to other types of turbomachine.

[0054] The propeller is rotatable around the X axis. For this, the propeller module may comprise a rotor 2 movable around the X axis relative to a casing 3.

[0055] The rotor 2 can be guided in rotation relative to the fixed casing 3 by at least one first bearing 5a located upstream and at least one second 5b and one third 5c bearing located downstream. The rotor 2 can comprise an internal annular shaft 6, called the fan shaft, which is centered on the axis X, and an external annular shell 7 which is also centered on the axis X and extends around the shaft 6. In the example, an upstream axial end 6a of the shaft 6 is flanged to an upstream axial end 7a of the shell 7, so that the shaft 6 and the shell 7 define between them an annular space 8 commonly called the “oil enclosure”.

[0056] The shaft 6 of the rotor 2 is driven by a power turbine downstream of the propeller module S via a speed reducer 9.

[0057] The propeller comprises a plurality of blades 4 with variable pitch. Each blade 4 with variable pitch comprises a blade 40, also with variable pitch, pivotally mounted about a pitch axis D.

[0058] The blade 40 may have an aerodynamic profile and comprise a lower surface and an upper surface which are connected by an upstream leading edge and by a downstream trailing edge (not shown). The blade 40 has an upper end which is free, called the tip, and a lower end which is connected to a root, for example in the form of a bulb-shaped attachment.

[0059] The setting axis D is an axis around which the angular position of the blade 40 is adjusted. This axis D is substantially perpendicular to the axis X.

[0060] The propeller module comprises a device 10 for controlling the pitch of the blades 40 which therefore makes it possible to regulate the angular position of each of the blades 40 around their axis D. This angular position corresponds for a blade 40 to the angle, in a longitudinal plane perpendicular to the axis D, between the chord of the blade 40 and the plane of rotation of the propeller.

[0061] The control device 10 may comprise a single actuator 11 common to all the blades 40 of the propeller. For example, this actuator may be connected to connecting rods at the blade roots or to a rod (not shown) which acts on pinions fixed to the blades, notably by surrounding the blade feet.

[0062] The propeller module comprises a device 12 for feathering the blades 40, in particular in the event of failure (or breakdown) of the control device 10, for example in the event of failure of the actuator 11.

[0063] The feathering device 12 comprises at least one lever 13 and a weight 14. In a similar manner to [Fig. 1], the lever 13 of [Fig. 4] has a first end 13a and a second end 13b opposite the first end 13a. The weight 14 is integral with the first end 13a. The weight 14 is capable, under the centrifugal effect, of being moved into a position in which the blades 40 are in a flag position.

[0064] The feathering device 12 further comprises an assembly 100 intended to connect the components of the feathering device 12 with the control device 10 and propeller blades 40. The assembly 100 comprises an annular casing 120 and an annular row of yokes 140. The casing 120 is intended to be connected to each propeller blade 40. At least one yoke 140 of the annular row of yokes 140 is intended to be connected to the second end 13b of the lever 13.

[0065] The blade feathering device 12 may also comprise a connecting rod 15 and a connecting rod 16 which has a first axial end 16a and a second axial end 16b opposite the first axial end 16b. In a similar manner to [Fig. 1], the connecting rod 15 of [Fig. 4] may be connected, on the one hand, to the yokes 140 (in particular to one of the two bearing supports 142, 144 of the yokes 140), and on the other hand, to the first axial end 16a of the connecting rod 16a. The second end 16b of the connecting rod 16 is connected to the blade pitch control device 12.

[0066] With reference to [Fig. 5], the annular casing 120 extends around an axis A. The axis A may be parallel to the axis X, in particular when the assembly 100 is assembled in the turbomachine 1.

[0067] The casing 120 comprises a first annular wall 122 which extends perpendicular to the axis A. The first annular wall 122 may have an axial dimension Li22 measured along the axis A, and a first width li22 measured along an axis transverse to the axis A. This first annular wall 122 is configured to be connected to the annular row of yokes 140.

[0068] The first annular wall 122 may comprise a plurality of first projections 128. The first projections 128 may be distributed around the axis A. Each first projection 128 may have a first radial dimension H[28 measured along an axis perpendicular to the axis A. This first radial dimension H[28 may represent at least 50% of the axial dimension Li22 of the first annular wall 122. For example, the first radial dimension H[28 represents at least 70% of the axial dimension Li22. Each first projection 128 may have a second width 1[28 measured along an axis transverse to the axis A. This second width 1128 can represent at least 70% of the first width 1122. The number of first projections 128 can be identical to the number of yokes 140, for example a number of ten.

[0069] The casing 120 may also comprise a second annular wall 124 which extends parallel to the first annular wall 122. This second annular wall 124 is configured to be connected, in particular indirectly, to the propeller blades 40.

[0070] The first 122 and the second 124 annular walls may be connected to each other by a cylindrical wall 126 of the casing 120. The cylindrical wall 126 extends in particular on the side opposite the first projections 128 of the first annular wall 122. This cylindrical wall 126 may be perforated.

[0071] The first 122 and the second 124 annular walls, the cylindrical wall 126 and the first projections 128 may be monobloc (i.e. made of one material).

[0072] The casing 120 (in particular the first wall 122 and the first projections 128) may be made of a first material, such as aluminum or titanium (for example the titanium alloy Ta6V).

[0073] The yokes 140 are distributed around the axis A. Each yoke 140 may have a general U shape. Each yoke 140 of the annular row of yokes may be formed from a single piece. Each of the yokes 140 may comprise two supports, such as ball bearing supports (called bearing supports in the present application), respectively first bearing support 142 and second bearing support 144, parallel to each other and connected to each other by a partition 146. Each of the partitions 146 may extend parallel to and opposite the first annular wall 122. Thus, the first 142 and second 144 bearing supports and the partition 146 of each of the yokes 140 may be single-piece (i.e., made in one piece).

[0074] Each of the first 142 and second 144 bearing supports may comprise, respectively, a first through opening 143a and a second through opening 143b. For example, the first bearing support 142 may be connected to the second end 13b of the lever 13 by the first through opening 143a. The second bearing support 144 may be connected to the connecting rod 15 by the second through opening 143b.

[0075] Each yoke 140 may comprise at least one second projection 148. In the example of [Fig. 5], the second projection 148 of each yoke 140 extends from the partition 146, in particular on the opposite side of the first 142 and second 144 bearing supports. The second projection 148 may have a second radial dimension Hi48 measured along an axis perpendicular to the axis A. This second radial dimension H[48 may represent at least 50% of the axial dimension Li22 of the first annular wall 122. For example, the second radial dimension H[48 represents at least 70% of the axial dimension Li22. Advantageously, the first radial dimension H[28 and the second radial dimension HM8 are identical. The second projection 148 may have a third width 1148 measured along an axis transverse to the axis A. This third width 1M8 may represent at least 70% of the first width 1122. Advantageously, the second width 1128 and the third width 1U8 are identical. The number of second projections 148 (and consequently of the yokes 140) for an assembly 100 may be identical to the number of first projections 128, for example a number of ten.

[0076] Each yoke 140 (in particular the partition 146 and the second projections 148) can be made of a second material, such as aluminum or titanium (for example, the titanium alloy Ta6V). The second material of the yokes 140 can be the same as or different from the first material of the housing 120.

[0077] Each of the yokes 140 is fixed to the first annular wall 122 of the casing 120.

[0078] One of the distinctive features of the invention is that the housing 120 and the yokes 140 are one-piece (i.e., made from a single piece of material). In this way, the mechanical strength during operation of the assembly 100 is improved, while limiting the mass and size of this assembly 100 in the propeller module S (and therefore in the turbomachine 1).

[0079] Each of the slabs 140 can be connected to the first annular wall 122 by a wall 130. This wall 130 can have a general elongated shape in the radial direction (with respect to the axis A).

[0080] The wall 130 can include a first portion located on the side of the first annular wall 122 and a second portion located on the side of the clevis 140. Each of the first projections 128 of the first annular wall 122 can thus form the first portion of the wall 130 and each of the second projections 148 of the clevises 140 can form the second portion of the wall 130. Thus, the clevises 140 and the housing 120 are joined together by a monobloc connection formed in particular by the first 128 and second 148 projections.

[0081] Advantageously, the first material of the casing 120 (in particular the first wall 122 and the first projections 128) is different from the second material of the yokes 140 (in particular the second projections 148). For example, the first material is made of aluminum and the second material is made of Ta6V titanium alloy, so as to reduce the mass of the assembly 100.

[0082] By way of example, the assembly 100 of [Fig. 2] of the prior art has an implementation weight (corresponding to the mass of the assembly 100) in forging of approximately 416 kg, whereas the assembly 100 of [Fig. 5] of the invention has an implementation weight in forging of approximately 484 kg. Thus, the assembly 100 of the invention allows a weight saving (approximately 68 kg) and a reduction in machining times compared to the prior art.

[0083] The present application will now describe a method of producing the assembly 100 described above with reference to [Fig.5].

[0084] [Fig.6] represents a block diagram of the steps of this method, the optional steps of which are illustrated in dotted lines.

[0085] Generally speaking, the production method comprises the following successive steps in particular: (a) production, on the one hand, of the annular casing 120, and on the other hand, of the yokes 140; (b) positioning at least one of the yokes 140 opposite, for example the first annular wall 122, the annular casing 120; (c) joining the yoke 140 to the annular housing 120 in a single piece by welding; and (d) repeating steps (b) to (c) for all the yokes 140 of the assembly (100).

[0086] In step (a), the yokes 140 and the annular housing 120 are therefore produced separately by conventional manufacturing of these parts.

[0087] Steps (b) and (c) can be carried out in a suitable machine, in which the annular housing 120 is placed on a machine frame, and then each yoke 140 is placed on a retaining support which is movable relative to the frame.

[0088] Advantageously, the annular casing 120 (in particular the first projections 128) and / or the yoke 140 (in particular the second projections 148) have an excess thickness measured relative to the axis A. This excess thickness may be between 1 and 5 mm, for example 2 mm, for the annular casing 120 and / or the yoke 140.

[0089] A surface preparation step (i) of each yoke 140 and / or of the annular casing 120 may be carried out before step (b). The surface preparation may be carried out by machining so as to form a flat surface.

[0090] The welding of step (c) can be carried out by linear friction. For this and for example, each yoke 140 is positioned, in a first step, against the casing 120 under a pressure force between two contacts, in particular the first and second projections 128, 148. In a second step, a high-frequency axial displacement of the yoke 140 is carried out while maintaining the pressure. The combination of the two forces makes it possible to create the connection between the two parts (namely the yoke 140 and the annular casing 120). When the two parts of the parts (for example the first 128 and second 148 projections) pressed against each other come into contact, the friction forces cause a resistance torque. This resistance torque created (corresponding to mechanical energy) is transformed into heat in the contact surface.The heat generated increases the temperature in a relatively short time up to the welding temperature (or so-called forging temperature). In a final step, the high-frequency axial movement of the yoke 140 is interrupted, but the pressurizing force is maintained for the time of cooling of a contact zone (in particular the first and second projections 128, 148 of the annular casing 120 and the yoke 140) to guarantee the connection between the two parts. 120, 140.

[0091] At the end of step (c), the single-piece connection by welding makes it possible in particular to form the web 130 of the assembly 100, in which the first 128 and second 148 projections are irreversibly connected.

[0092] During the heating phase and the welding phase, a quantity of material (originating from the yoke and / or the annular casing) can be pushed outwards, under the influence of the axial pressure force, so that a welding bead can be formed (not shown in the figures). The welding bead formed at the connection between the yoke 140 and the annular casing 120 (in particular between the first 128 and second 148 projections) can be in the form of a bead.

[0093] The manufacturing process may also include a machining step (ii) of the weld bead formed in step (c) so as to obtain a smooth surface at the welded joint.

[0094] In the case of linear friction welding, the welding parameters may vary depending on the dimensions of the first and second projections 128, 148. These dimensions (for example the widths li2s, lus and the radial dimensions H^s, Hi48) meet the need for mechanical strength of the part 100 to ensure that the zone does not break. The welding parameters are, for example: - the section of the parts (120, 140) to be welded, - the friction force, and - the forging force.

[0095] Table 1 below summarizes the welding parameters carried out on a first test (welding section of approximately 8606 mm2) and a second test (welding section of approximately 2209 mm2) of linear friction welding.

[0096] [Tables 1] Test 1 Test 2 Section to be welded (mm2) 8606 2209 Material excess thickness on the 140 yoke (mm) 2 2 Material excess thickness on the 120 casing (mm) 2 2 Material removal on the 140 yoke at step (i) (mm) 2.5 2.5 Material removal on the 120 casing at step (i) (mm) 2.5 2.5 Friction force (kN) 223 17.3 Forging force (kN) 250 17.3 Mass of the assembly 100 for a number of ten 140 yokes (Kg) 47.4 37.2

[0097] Linear friction welding is also suitable for joining two different materials.

[0098] In this description, the assembly 100 according to the invention is described in a shrouded propeller module S of a dual-flow turbomachine. Of course, the propeller module S of the invention can also be unshrouded (such as in an open-rotor).

[0099] The present invention provides several advantages, such as: - improve mechanical strength depending on the set 100; - reduce the mass and size of the assembly 100 (and consequently of the turbomachine 1); - reduce the loss of material from the set 100; - remove additional assembly parts (such as screws, nuts, bolts, etc.); - facilitate the machining of the bearing supports 142, 144 of the yokes 140;

[0100] - reduce the time taken to produce the set 100 (such as the cycle time of forging, machining time, etc. compared to the prior art); - requires little or no adaptation in the S propeller module; - easy integration during assembly and maintenance in the propeller module S (and therefore in the turbomachine 1).

[0101] Generally speaking, the invention makes it possible to improve the performance of the engine of a turbomachine. The solutions proposed in the present application are simple, efficient and economical to produce and assemble in a turbomachine, while increasing the service life of the assembly 100 (and therefore of the variable pitch blades) in operation.

Claims

Claims

1. Assembly (100) for a feathering device (12) for variable-pitch blades (40) of an aircraft turbomachine propeller (1), the assembly (100) comprising: - an annular casing (120) which extends around an axis (A) and which has a first annular wall (122) extending perpendicular to said axis (A), and - an annular row of yokes (140) which are distributed around the axis (A) and which are carried by said first annular wall (122), each of the yokes (140) being formed in one piece and comprising two bearing supports (142, 144) parallel to each other and to a plane passing through said axis (A), characterized in that the annular casing (120) and the annular row of yokes (140) are in one piece, and in that each of the yokes (140) is connected to the first annular wall (122) by a web (130) which has a generally elongated shape in the radial direction.

2. Assembly according to claim 1, characterized in that said web (130) comprises a first portion located on the side of the first annular wall (122) and formed by a first projection (128) of this first annular wall (122), and a second portion located on the side of each of the yokes (140) and formed by a second projection (148) of this yoke (140).

3. Assembly according to claim 2, characterized in that the number of first projections (128) is equal to the number of second projections (148) and yokes (140).

4. Assembly according to claim 2 or 3, characterized in that the first and second projections (128) have radial dimensions (Hi28, H i48) which represent at least 50% and preferably at least 70% of an axial dimension (Li22) of the first annular wall (122).

5. Assembly according to claim 2 or 3, characterized in that the bearing supports (142, 144) of each of the yokes (140) are connected to each other by a partition (146) which extends parallel to and opposite the first annular wall (122) and on which the second projection (148) of this yoke (140) is formed.

6. Assembly according to any one of the claims, characterized in that the annular casing (120) is made of a first material, for example in aluminum, different from a second material, for example in titanium, of the clevises (140).

7. Propeller module (S) for an aircraft turbomachine (1), comprising: - a propeller rotatable about a longitudinal axis (X) and comprising a plurality of variable-pitch blades (4), each blade (4) comprising a blade (40) pivotally mounted along a pitch axis (D) perpendicular to the longitudinal axis (X), - a device (10) for controlling the pitch of the blades (40), and - a device (12) for feathering the blades (40), in particular in the event of failure of said control device (10), comprising: - at least one lever (13) having a first end (13a) and a second end (13b) opposite this first end (13a), and - a weight (14) secured to the first end (13a) of the lever, said weight (14) being capable, under the centrifugal effect, of being moved into a position in which the blades (40) are in a flag position,characterized in that the propeller module (S) comprises at least one assembly (100) according to any one of the preceding claims, in which one of the two bearing supports (142, 144) of each yoke (140) is connected to the second end (13b) of the lever, and the annular casing (120) is configured to be connected to each blade (40) of variable-pitch vanes by a second annular wall (124).,

8. Turbomachine module according to claim 7, characterized in that the feathering device (12) of the blades further comprises: - a connecting rod (15) connected to the other of the two bearing supports (142, 144) of each yoke (140), and - a connecting rod (16) which has a first axial end (16a) connected to the connecting rod (15) and a second axial end (16b) opposite the first axial end (16a) and connected to the control device (12) for the pitch of the blades (40).

9. Aircraft turbomachine (1) comprising a propeller module (S) according to claim 7 or 8, and a gas generator (G) intended to drive the propeller.

10. Method for producing an assembly (100) according to one of claims 1 to 6, comprising the steps of: (a) producing, on the one hand, the annular casing (120), and on the other hand, the yokes (140); (b) positioning one of the yokes (140) opposite the annular casing (120); (c) integrally connecting the yoke (140) to the annular casing (120) by welding; and (d) repeating steps (b) and (c) for all the yokes (140) of the assembly (100).

11. Production method according to claim 10, characterized in that the welding of step (c) is carried out by linear friction.

12. Production method according to claim 10 or 11, characterized in that the method further comprises, before step (b), a step (i) of surface preparation of the yokes (140) and / or the annular casing (120).

13. Method according to any one of claims 10 to 12, characterized in that it comprises, after step (c), a step (ii) of machining a welding bead formed at the connection between the yoke (140) and the annular casing (120) in step (c).

Images