VARIABLE PITCH BLADE FAN MODULE

Abstract

The invention relates to a fan module with variable-pitch blades for a propulsion unit with a longitudinal axis (X), comprising: a rotating casing (3) carrying the blades, and a device (38) for feathering the blades comprising at least one mechanism (39) having a lever (40) secured to a flyweight (43) and a cap (70) attached to the rotating casing, the lever being articulated relative to the cap by a pivot connection and being coupled to a synchronization ring (34) of a connection mechanism (24) of a system (22) for changing the pitch of the blades, the flyweights being capable, under the centrifugal effect, of being moved into a position in which the synchronization ring imposes a flag position on the blades, the cap (70) comprising two successive linear walls (72, 74) configured to collect a liquid lubricant and discharge said lubricant into a downstream portion (71) of the rotating casing. Figure for abstract: Figure 4

Description

Title of the invention: VARIABLE PITCH BLADE FAN MODULE Technical field

[0001] The present invention relates to the field of aircraft turbomachines and more particularly to a variable-pitch fan module for a propulsion unit comprising a system for changing the pitch of the blades and a device for feathering them. The invention also relates to a method for assembling such a module and the corresponding propulsion unit. Prior art

[0002] A fan equipped with variable pitch blades (known by the English acronym VPF for "Variable Pitch Fan") makes it possible to adjust the pitch (and more precisely the pitch angle) of the blades according to the flight parameters, and thus to optimize the operation of the fan, and generally of the propulsion unit in which such a fan is integrated. As a reminder, the pitch angle of a blade corresponds to the angle, in a longitudinal plane perpendicular to the axis of rotation of the blade, between the chord of the blade and the plane of rotation of the fan.

[0003] Propulsion units or turbomachines are known which generally comprise a shrouded fan or an unshrouded propeller equipped with variable pitch moving blades, equipped with these pitch change systems.

[0004] In the category of turbomachines with at least one unducted propeller, also called by the English term "open rotor" or "unducted fan", there are those having a single unducted propeller and a rectifier comprising several stator blades (known by the English acronym USF for "Unducted Single Fan").

[0005] An open rotor type turbomachine mainly comprises, inside a fixed cylindrical casing carried by the structure of the aircraft, a coaxial “gas generator” part and a “propulsion” part. The gas generator part can be arranged upstream or downstream of the propulsion part. The terms “upstream” and “downstream” are defined in relation to the circulation of gases in the turbomachine. The propulsion part comprises at least one propeller driven in rotation by a turbine, in particular a low pressure turbine, of the gas generator part via a reducer, for example, with epicyclic gear trains. The propeller or propellers extend substantially radially with respect to the transmission shaft with a longitudinal axis outside the casing.

[0006] Generally, each propeller comprises a substantially cylindrical rotating casing carrying a hub comprising an outer blade support ring rotatably received around the longitudinal axis in the stator of the turbomachine. The ring has radial cylindrical housings distributed on its periphery around the longitudinal axis. Shafts with radial axes, perpendicular to the longitudinal axis of the turbomachine, integral with the blade roots are received in the housings of the ring and also pass through radial passages of the cylindrical casing.

[0007] To enable the turbomachine to operate optimally according to the different flight phases encountered, the blades of the propeller(s) can rotate in the radial housings of the hub ring. For this, they are driven in rotation around their respective pivot axes, called the pitch axis, by an appropriate system making it possible to vary the pitch of the blades during flight, i.e. the pitch of the propellers.

[0008] This system for changing the pitch of the propeller blades covers an angular range of rotation between two extreme positions, namely an extreme position called "reverse" for which the blades protrude for example by 30° the plane transverse to the axis of the turbine engine (the direction of advance of the aircraft) to participate in the braking of the aircraft, in the manner of conventional thrust reversers, and an extreme position called "feathering" for which the blades are then retracted as much as possible relative to the direction of advance, for example, in the event of engine failure or during a failure (or breakdown) of the blade pitch control device (for example a failure of a hydraulic actuator) so that the latter offer the least resistance (drag) possible.

[0009] Generally, a system for changing the pitch of the blades of a propeller comprises a control device and a connecting mechanism connecting the control means to each blade of the propeller to ensure the desired angular pivoting of the blades.

[0010] In addition, the blades are generally feathered using counterweights. Usually, the counterweights are placed on the root of each blade and are potentially very heavy depending on the available space and cause centrifugal loading and therefore increase the stresses on the root of the blades and the already highly stressed blade root bearings.

[0011] Different solutions have been proposed for changing the pitch of the blades of a fan and for feathering the blades on turbomachines of the “open rotor” type or others.

[0012] For example, document FR 3 066 559 discloses a blade pitch change system comprising a single annular cylinder arranged on a fixed casing or internal stator relative to the hub of the fan and a connecting mechanism comprising a transfer bearing, better known by the English acronym LTB for “Load Transfer Bearing”, fixed on one side to the mobile part of the cylinder and cooperating, on the other side, with a means for connecting the mechanism to the blades of the rotating hub, such that the load transfer bearing of the rotating mechanism transmits the translational movement of the moving part of the fixed cylinder, by means of connecting the rotating mechanism to change the orientation of the propeller blades. This pitch change system further comprises a blade feathering device comprising counterweights with a lever mechanism arranged in the rotating reference, linked to the outer ring of the load transfer bearing. The use of counterweights with a lever mechanism acting on the cylinder makes it possible to multiply the force and to take advantage of an empty space to reduce the mass of the counterweights and not to stress the root of the blades.

[0013] Having a linear actuator in a fixed frame of reference makes it easier to supply it with oil and to reduce the rotating masses. However, this solution requires a plane kinematics of the counterweight mechanism, implying that the pitch change mechanism has a purely axial movement. This need for purely axial movement leads to an oversizing of the lever system. In addition, if the pitch change mechanism is purely axial it requires a greater force for actuation and this force translates into internal forces and therefore into additional mechanical stresses. Furthermore, the lever counterweight mechanism as presented is hyperstatic making its dimensioning, manufacturing and assembly difficult.

[0014] Furthermore, the lever mechanism according to this solution has a cavity with a discharge pipe, for discharging the oil necessary for the pitch change mechanism and has load transfer bearings which require lubrication, which can be technically complicated.

[0015] The objective of the present invention is thus to propose a blade feathering device making it possible to overcome at least some of these drawbacks. Summary of the invention

[0016] To this end, the invention relates to a fan module with variable-pitch blades for a propulsion unit with a longitudinal axis, said module comprising:

[0017] - a casing rotating around the longitudinal axis X and carrying the blades,

[0018] - a system for changing the pitch of the blades comprising a device for control and a connecting mechanism, the control device comprising an annular actuator centered on the longitudinal axis X having a fixed body attached to the rotating casing and a body movable in translation relative to the fixed body along the longitudinal axis X, the movable body being coupled to a synchronization ring of the connecting mechanism, said synchronization ring being connected to the blades and configured to be driven in rotation around the longitudinal axis by the body movable so as to change the pitch of the blades; and

[0019] - a device for feathering the blades, in particular in the event of failure of said control device, said feathering device comprising at least one mechanism having a lever secured to a weight and a cap attached to the rotating casing, the lever being articulated relative to the cap by a pivot connection and being coupled to the synchronization ring, the weights being capable, under the centrifugal effect, of being moved into a position in which the synchronization ring imposes a flag position on the blades,

[0020] characterized in that the cap comprises two successive linear walls configured to collect a liquid lubricant and discharge said lubricant into a downstream part of the rotating casing.

[0021] The invention thus makes it possible to achieve the aforementioned objective. In particular, it makes it possible to ensure passive feathering of the blades of an efficient fan by multiplying the centrifugal force of each flyweight while having low return forces during the thrust reversal phase.

[0022] Furthermore, the invention being without load transfer bearing, makes it possible to limit the propagation of fluids, in particular lubricating oil. Drainage of potential leaks from the actuator remains useful, however the invention no longer has a cavity or pipe.

[0023] The geometries of the lever system of the feathering device are advantageously adapted so as to present a double slope in the support part which thus allows the flow of the lubricant which is thus no longer trapped in a cavity and no longer requires evacuation pipes.

[0024] The blower module according to the invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

[0025] - the two successive linear walls of the hat comprise a linear wall upstream and a downstream linear wall arranged between the upstream linear wall and the downstream part of the rotating casing intended to receive the lubricant discharged by the cap, the downstream linear wall being substantially parallel to the longitudinal axis of the propulsion unit;

[0026] - at least one lever is coupled to the synchronizing crown via a connecting rod articulated at each of its ends;

[0027] - the connecting rod has a pivot connection at each of its ends;

[0028] - the connecting rod has a ball joint at each of its ends;

[0029] - the cap internally defines a cavity, each lever comprising a first branch located outside the cavity and a second branch located inside the cavity, the two branches being fixed relative to each other;

[0030] - the articulation between the levers and said cap comprises sealing means.

[0031] The invention also relates to a propulsion assembly with a longitudinal axis comprising at least one fan module with variable-pitch blades according to the invention and as described previously.

[0032] Another object of the invention relates to a method of mounting a variable-pitch blade fan module as described above, comprising:

[0033] - a step of pre-assembly of the sub-assemblies each formed from a mechanism of the blade feathering device;

[0034] - a step of coupling each subassembly to the synchronization crown, each subassembly being in the reverse thrust position and the synchronization ring being in the flag position; and

[0035] - a step of positioning and fixing the cap on the rotating casing in tilting the lever to the flag position. Brief description of the drawings

[0036] The present invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which:

[0037] [Fig-1] [Fig.l] is an axial (or longitudinal) half-sectional view of a module of fan according to the invention comprising a device for feathering the blades, in a first position, along an axial plane passing through the axis of rotation of a blade of the fan;

[0038] [Fig.2] [Fig.2] is a three-dimensional view of [Fig.l],

[0039] [Fig.3] [Fig.3] is a partial sectional view of [Fig.2] along an axial plane passing through the axis of rotation of a fan blade and the longitudinal axis of the module in which the blade feathering device is in a second position;

[0040] [Fig.4] [Fig.4] is a partial sectional view of [Fig.2] along an axial plane passing through the axis of rotation of a fan blade and the longitudinal axis of the module in which the blade feathering device is in the first position;

[0041] [Fig.5] [Fig.5] is a schematic view in radial (or transverse) section of a mechanism of the blade feathering device, according to a plane passing through the axis of rotation of the lever of said mechanism;

[0042] [Fig.6] [Fig.6] represents an alternative to the mechanism of the putting device in flag of the blades of [Fig.5] in radial (or transverse) section along a plane passing through the axis of rotation of the lever;

[0043] [Fig.7] [Fig.7] illustrates a first step of a method of assembling a module blower according to the invention;

[0044] [Fig.8] [Fig.8] illustrates a step subsequent to the step illustrated in [Fig.7] of a method of assembling a blower module according to the invention; and

[0045] [Fig.9] [Fig.9] illustrates a step subsequent to the step illustrated in [Fig.8] of a method of assembling a blower module according to the invention.

[0046] Elements having the same functions in different implementations have the same references in the figures. Description of the embodiments

[0047] The invention applies to a propulsion unit intended to be mounted on an aircraft. The aircraft comprises a fuselage and at least two wings extending on either side of the fuselage along the axis of the fuselage. At least one propulsion unit is mounted, for example, under each wing. The propulsion unit may be a turbojet, for example a propulsion unit equipped with a ducted fan (turbofan) or a turboprop, for example a propulsion unit equipped with an unducted propeller ("open rotor", "USF" for "Unducted Single Fan" or "UDF" for "Unducted Fan"). Of course, the invention applies to other types of propulsion units, for example comprising two coaxial and counter-rotating propellers.

[0048] Generally speaking and in the remainder of the description, the term “fan” is used to designate either a ducted fan or a propeller.

[0049] Figures 1 to 4 show a fan 1 of a propulsion unit 2 with a longitudinal axis X. The fan 1 comprises a rotating casing or a rotor 3 movable around the axis X relative to a fixed casing, the rotor 3 carrying a series of variable-pitch blades 5. The fan 1 is here placed upstream of the engine part of the propulsion unit 2 which comprises, for example, successively from upstream to downstream, a gas generator and a power turbine which drives the rotor 3 of the fan 1 via a speed reducer.

[0050] By convention, in the present application, the terms "upstream" and "downstream" are defined relative to the direction of circulation of the gases in the fan 1 (or propulsion unit 2) and here along the longitudinal axis X (and even from left to right in [Fig.l]). Similarly, by convention in the present application, the terms "internal" and "external", "interior" and "exterior" are defined radially relative to the longitudinal (or axial) axis X of the propulsion unit 2, which is in particular the axis of rotation of the rotors of the compressors and turbines of the gas generator.

[0051] The rotating casing 3 comprises an internal annular shaft 10 centered on the X axis which, in operation, is driven by the power shaft 11 via the speed reducer 12 and a ring 16 for supporting the blades 5.

[0052] More precisely, each blade 5 comprises a foot which is for example in the form of a bulb-shaped attachment, this foot being integral with a pivot 18 mounted in a housing 19 of a base 20 projecting from the ring 16 in a movable manner in rotation around a substantially radial Y axis via two rolling bearings. The rolling bearings placed 21 in each housing 19 are generally grease lubricated.

[0053] The fan 1 comprises a system 22 for changing the pitch of the blades 5 or a system for setting the blades 5 around their axis Y, and more precisely the setting angle of the blades 5 which corresponds for a blade 5 to the angle, in a longitudinal plane perpendicular to the axis Y, between the chord of the blade 5 and the plane of rotation of the fan 1.

[0054] The blades 5 are set in the “reverse thrust” position (known by the English designation “reverse”) in [Fig. 3]. In the “reverse thrust” position, the pitch angle of the blades 5 is negative. This position of the blades 5 makes it possible to generate counter-thrust, and thus to participate in slowing down the aircraft in addition to the brakes so as to reduce its braking distance during landing.

[0055] The blades 5 are set in the flag position in Figures 1, 2 and 4. In the flag position, the setting angle is positive and generally close to 90°. This position of the blades 5 makes it possible to limit the resistance (drag) generated by the latter.

[0056] According to the embodiment illustrated in the figures and in particular figures 1 to 4, the pitch change system 22 of the blades 5 comprises a linear annular control device or actuator 23, centered on the axis X, common to all the blades 5 and a connecting mechanism 24 connected to each blade 5, this connecting mechanism 24 making it possible to transform the linear movement initiated by the actuator 23 into a rotational movement of the corresponding blade 5.

[0057] More precisely, the linear actuator 23 comprises a fixed annular body 25 attached to an annular support (centered on X) of the rotary casing 3 and a movable body 27. The movable body 27 is movable in translation relative to the fixed body 25 along the axis X. Advantageously, the linear actuator 23 is hydraulic. Preferably, the actuator 23 is a hydraulic cylinder comprising a fixed piston secured to the shaft of the rotor 3 forming the fixed body 25 of the actuator and a body forming the movable body 27 of the actuator.

[0058] The connecting mechanism 24 of the pitch change system 22 further comprises a synchronization ring 34 secured to the movable body 27 of the actuator 23. The synchronization ring 34 is centered on the longitudinal axis X and is intended to drive the setting of blades 5 simultaneously.

[0059] The connecting mechanism 24 making it possible to transform the linear movement of the actuator into a rotational movement of the blade 5 further comprises, for each blade 5, a connecting rod 35. One of the ends of the connecting rod 35 is mounted so as to rotate freely along an axis D (visible in [Fig.l]) substantially radial with the synchronization ring 34 via a yoke and the other end ... freely rotating manner with an eccentric 36 connected to the root of the corresponding blade 5 via, for example, a spline connection. The axis D is offset relative to the Y axis of rotation of the blade 5. The connecting rod 35 and the eccentric 36 make it possible to multiply the force required to adjust the setting of the corresponding blade 5.

[0060] The linear movement of the movable body 27 of the actuator 23 makes it possible to adjust the timing of all the blades 5 in a synchronized manner, in particular via the synchronization ring 34.

[0061] The fan 1 also comprises a device 38 for feathering the blades 5, in particular in the event of failure (or breakdown) of the pitch change device 22, and for example a failure in the hydraulic supply of the linear actuator 23. As a reminder, the flag position corresponds to a positive setting generally substantially equal to 90°.

[0062] The feathering device 38 comprises at least one mechanism 39 comprising at least one lever 40 articulated around an axis A fixed relative to the rotor 3. The axis A is here rectilinear and perpendicular to the axis X. The lever 40 has a first end 41 and a second end 42. A flyweight 43 is integral with the first end 41 and the second end 42 is coupled to the synchronization ring 34. The flyweight 43 is capable, under the centrifugal effect, of being moved into a position remote from the longitudinal axis X (see figures 1, 2 and 4) in which the synchronization ring 34 imposes a flag position on the blades 5. The mechanisms 39 of the feathering device 38 are distributed angularly in a regular manner around the axis X. Thus, all of the flyweights 43 form an annular row centered on the longitudinal axis X and spaced angularly in a regular manner.

[0063] According to the embodiment illustrated in the figures, for each mechanism 39, the lever 40 has an L or V shape in axial section. The lever comprises two angularly spaced branches connected at the level of the articulation of the lever at A by a pivot connection preferably, a first branch 44 supporting the weight and a second branch 45 coupled to the synchronization ring 34 via the connecting rod 60. The first branch 44 comprises two synchronized parallel arms located radially outside the rotating casing 3. The length of the first branch 44 is greater than the length of the second branch 45, approximately twice as long in the present case. This length ratio makes it possible to multiply the force provided by each weight 43, and in other words to minimize their mass, and more generally, the mass of all the weights 43.

[0064] The second end 42 of the lever 40 and an upstream axial end of the connecting rod 60 are coupled by a first pivot joint 62. Similarly, a downstream axial end of the connecting rod 60 and the synchronizing crown 34 are preferably coupled by a second pivot joint 63.

[0065] Alternatively, the second end 42 of the lever 40 and the upstream axial end of the connecting rod 60 are preferably coupled by a spherical articulation, commonly called a ball joint or ball joint. Similarly, the downstream axial end of the connecting rod 60 and the synchronizing ring 34 are preferably coupled by a second spherical articulation.

[0066] Furthermore, each mechanism 39 of the feathering device 38 of the blades 5 comprises a cap 70 attached to the rotary casing 3. More precisely, the rotary casing comprises an upstream portion 75 extending substantially parallel to the longitudinal axis X and a downstream portion 71 connected by a frustoconical intermediate portion 76 widening from upstream to downstream. Each cap 70 is attached and fixed to the frustoconical intermediate portion 76 of the rotary casing 3 by means of screws. Sealing means, for example a gasket, are interposed between the cap 70 and the frustoconical intermediate portion 76 of the rotary casing 3, to guarantee the seal between them.

[0067] Each cap 70 comprises two successive linear walls configured to collect a liquid lubricant and discharge said lubricant into a downstream portion 71 of the rotating casing 3. More specifically, each cap 70 comprises an upstream linear wall 72 and a downstream linear wall 74. The downstream linear wall 74 is arranged between the upstream linear wall 72 and the downstream portion 71 of the rotating casing 3 intended to receive the lubricant discharged by the cap 70. The upstream 72 and downstream 74 linear walls form an angle whose apex projects radially outwards so as to allow the counterweight kinematics to move freely without interference while having slopes adapted to the discharge of the oil without an oil retention zone. Preferably, this angle is between 120° and 130°, defining internally between the upstream 72 and downstream 74 linear walls a cavity 77 (figures 1 to 4).The first branch 44 of each lever 40 is located outside the cavity 77 while the second branch 45 is located inside the cavity 77.

[0068] Furthermore, the downstream linear wall 74 is angularly spaced from the longitudinal axis X of the propulsion assembly by an angle greater than 0°, preferably between 1° and 4° to minimize the bulk while allowing the oil to be evacuated by centrifugation.

[0069] This geometry guarantees the evacuation of the lubricant received in the cavity 77 towards the downstream part 71 of the rotating casing.

[0070] As indicated previously, each lever is articulated relative to the rotating casing at A by a pivot connection by means of an axis 80 centered on A. This connection is illustrated in detail in [Fig. 5]. It includes plain bearings for guidance and sealing and also grooves for the transmission of torque.

[0071] More precisely, as illustrated in [Fig.5], the axis 80 crosses (transversely) part by part the cap 70 and is guided in rotation relative to the latter via rotation guide means 82. The rotation guide means 82 advantageously comprises plain bearings, preferably self-lubricated, ensuring good compactness. The plain bearings can be integrated directly on the cap 70 as shown here or attached to a support. They provide a certain seal along the pivot connection, but they can be supplemented by an additional sealing means not shown here.

[0072] The arms of the first branch 44 of the lever 40 laterally border the cap 70, each of them being linked in rotation to the axis 80 by first rotational connection means 84. The second branch 45 of the lever is interposed between the guide means 82 of the cap 70 and is linked in rotation to the axis 80 by second rotational connection means 86. The first and second rotational connection means 84, 86 are for example splines. The axis 80 is stopped axially at each of its ends by a nut 88, a washer 89 being interposed between the first branches 44 of the lever and the nuts 88.

[0073] Such a connection makes it possible to ensure the assembly of the lever by transmitting the torque. The dimensioning of the diameters and spans of the splines is constrained by the moment transmitted to the pivot. Thus, in the pivot connection illustrated in [Fig.5] the axis 80 is symmetrical, allowing easy disassembly of this connection.

[0074] Alternatively, the axis 80 may be non-symmetrical for the transmission of loads. [Fig.6] illustrates such an alternative. In this case, the arms of the first branch 44 of the lever may be formed in a single piece.

[0075] When the propulsion unit 2 is operating normally (no failure), the feathering device 38 is subordinate to the system 22 for changing the pitch of the blades 5, and more precisely to the linear actuator 23. It is noted that when the blades 5 are in the “thrust reversal” position, the weights 43 of the mechanisms 39 of the feathering device 38 of the blades 5 are close to the longitudinal axis X of the rotor 3 as illustrated in [Fig. 3].

[0076] In the event of a failure (need to position the blades 5 in the flag position), for example a failure in the hydraulic supply of the linear actuator 23, the system 22 for setting the blades 5 then becomes subordinate to the feathering device 38, and more precisely the flyweights 43 which, under the centrifugal effect, find themselves further away from the longitudinal axis X of the rotor 3 as illustrated in FIGS. 1, 2 and 4, to impose a flag position on the blades 5.

[0077] The lever counterweight mechanism thus acts on the cylinder which is kinetically linked to the blade actuation mechanism. The number of lever counterweights is thus independent of the number of blades. The lever counterweight mechanism imposes the direction of the flag position on the pitch actuation kinematics.

[0078] The invention also relates to a method for mounting a variable-pitch fan module as described above. The mounting method comprises a first step illustrated in [Fig.7] during which the two branches 44, 45 of the lever and the cap 70 are assembled by means of the axis 77. In addition, the free end of the second branch 45 of the lever is assembled to the connecting rod 60 in order to form a subassembly comprising a counterweight 43, a lever 40, a connecting rod 60 and a cap 70.

[0079] Then, in a second step illustrated in [Fig.8], the subassembly is positioned in the thrust reversal position and then brought towards the synchronization ring of the pitch change mechanism positioned in the flag position in order to attach the free end of the connecting rod 60 to the synchronization ring. The cap 70 can advantageously tilt around its axis in order to free up a passage for the hands of an installer.

[0080] Finally, with reference to [Fig.9], the cap 70 is positioned on the rotating casing by tilting the lever into the flag position. A seal is placed between the cap and the rotating casing. The cap 70 is then fixed to the rotating casing.

[0081] It is noted that the examples illustrated in the figures are in no way limiting, the blade pitch change system according to the invention could for example be incorporated into the rotor of a propeller of a turboprop or even into the rotor of each of the two propellers of a turbomachine comprising two counter-rotating propellers, better known by the English designation "Open Rotor". In the definition of the invention, the term "fan" also covers the propeller or propellers of such turbomachines.

[0082] Furthermore, in the examples illustrated in the figures, the piston of the cylinder is connected to the rotor (in the rotating frame of reference) and the body of the cylinder is movable in translation relative to the piston and fixed to the synchronizing ring. However, the invention could also be applied to a system in which the piston would be fixed to the synchronizing ring and movable in translation relative to the body of the cylinder. Thus, depending on the configuration of the cylinder, the entire feathering device is supported by a casing connected directly to the cylinder or to the structure of the engine.

[0083] Such a feathering device applies more generally to any turbomachine comprising a blade pitch control device for which a feathering device is necessary.

Claims

Claims

1. Fan module with variable pitch blades for a propulsion unit with a longitudinal axis (X), said module comprising: - a casing (3) rotating around the longitudinal axis (X) and carrying the blades, - a system (22) for changing the pitch of the blades comprising a control device (23) and a connecting mechanism (24), the control device comprising an annular actuator centered on the longitudinal axis (X) having a fixed body (25) attached to the rotating casing and a body (27) movable in translation relative to the fixed body along the longitudinal axis (X), the movable body being coupled to a synchronization ring (34) of the connecting mechanism, said synchronization ring being connected to the blades and configured to be driven in rotation around the longitudinal axis (X) by the movable body so as to change the pitch of the blades;and - a device (38) for feathering the blades, in particular in the event of failure of said control device, said feathering device (38) comprising at least one mechanism (39) having a lever (40) secured to a weight (43) and a cap (70) attached to the rotary casing, the lever being articulated relative to the cap by a pivot connection and being coupled to the synchronization ring, the weights being capable, under the centrifugal effect, of being moved into a position in which the synchronization ring imposes a flag position on the blades, characterized in that the cap (70) comprises two successive linear walls (72, 74) configured to collect a liquid lubricant and discharge said lubricant into a downstream part (71) of the rotary casing.;

2. Blower module according to claim 1, in which the two successive linear walls of the cap (70) comprise an upstream linear wall (72) and a downstream linear wall (74) arranged between the upstream linear wall (72) and the downstream part (71) of the rotating casing intended to receive the lubricant discharged by the cap, the downstream linear wall (74) being substantially parallel to the longitudinal axis (X) of the propulsion unit.

3. Blower module according to claim 1 or 2, in which at least one lever (40) is coupled to the synchronizing ring (34) via a connecting rod (60) articulated at each of its ends.

4. A blower module according to claim 3, wherein the link (60) has a pivot connection at each of its ends.

5. A blower module according to claim 3, wherein the connecting rod (60) comprises a ball joint at each of its ends.

6. Blower module according to one of the preceding claims, wherein said cap (70) internally defines a cavity (77), each lever (40) comprising a first branch (44) located outside the cavity and a second branch (45) located inside the cavity, the two branches being fixed relative to each other.

7. Blower module according to one of the preceding claims, in which the articulation between the levers and said cap comprises sealing means.

8. Propulsion assembly with longitudinal axis (X) comprising at least one fan module with variable-pitch blades according to one of the preceding claims.

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