Fan module for an aircraft turbomachine

Abstract

The invention relates to a blower module (3) comprising: - a blade pitch control system (96) comprising: - at least one safety device (97) comprising a safety member movable in translation about the longitudinal axis (X) and movable between: a first position (P1) in which the body (54) of the actuator (52) is free to move between its flag and pitch positions, and a second position (P2) in which the body (54) of the actuator (52) is driven towards the flag position and free to move along a limited stroke relative to a defined stroke between the flag and pitch positions, - a drive device (98) for the safety member, and - a control device (99) for the drive device (98). Illustration figure: 2

Description

Title of the invention: Fan module for an aircraft turbomachine Technical field of the invention

[0001] The invention relates to the field of fan modules for aircraft turbomachinery.

[0002] The invention relates in particular to blower modules comprising variable pitch blades.

[0003] The invention relates more particularly to blower modules comprising variable-pitch blades supported by a hub and a blade pitch change system comprising an actuator rotationally fixed to the hub. Technical background

[0004] In a well-known manner, an aircraft turbomachine extends along a longitudinal axis and comprises, from upstream to downstream, a blower, a low-pressure compressor, a high-pressure compressor, an annular combustion chamber, a high-pressure turbine and a low-pressure turbine.

[0005] The blower typically comprises a hub centered on the longitudinal axis and free to rotate about this axis. The blower further comprises blades regularly distributed around the hub.

[0006] To optimize fan operation, the blades are typically variable pitch. Variable pitch blades are those whose pitch, or orientation, and more specifically the pitch angle, can be modified according to flight parameters. The pitch angle of a blade corresponds to the angle, in a longitudinal plane perpendicular to the blade's axis of rotation, between the blade chord and the fan's plane of rotation. Variable pitch blades can thus occupy a thrust reversal position (known as "reverse") in which they generate counter-thrust to contribute to slowing the aircraft, and a feathering position in which, in the event of a failure or malfunction, they reduce drag. Between these two extremes, the blade can assume any position.

[0007] To vary the blade pitch angle, the blower typically includes a blade pitch change system. Such a system typically includes a hydraulic actuator rotatably fixed to the hub. The hydraulic actuator is configured to drive the blades in rotation about their pitch axes. The hydraulic actuator typically includes a housing centered on the axis A longitudinal axis and a moving body in translation along the longitudinal axis within the envelope. The moving body is connected to the blades, possibly via a linkage mechanism that transforms the translational movement of the body into a rotational movement of the blades. The moving body is thus translationally movable in one position where it imposes a feathering position and another where it imposes a thrust reversal position on the blades. Between these two extreme positions, the moving body can assume any position.

[0008] The hydraulic actuator is typically supplied with a fluid, typically oil, via a supply circuit, the pressure of the fluid in the casing causing the movement of the body.

[0009] In the event of failure of the hydraulic actuator, for example in the event of a break in the supply circuit or a break in one of the components of the hydraulic actuator, it is necessary to be able to secure the blades in the flag position.

[0010] To this end, document FR-A1-3 098 788 describes a blower module comprising a hub centered on the module axis and variable-pitch blades regularly distributed around the hub. The blower module further comprises a blade pitch-changing system including a hydraulic actuator rotatably fixed to the hub.

[0011] According to this document, the module further includes a blade pitch safety system in case of failure of the hydraulic actuator. The safety system comprises a set of weights capable of being moved under centrifugal force into a position in which the hydraulic actuator forces the blades into a flagging position.

[0012] However, such a safety system is not entirely satisfactory. Indeed, the weights act under the effect of centrifugal force, which makes the safety system unreliable and difficult to control. Furthermore, the hydraulic actuator must be oversized to counteract the additional forces exerted by the weights. Also, to reach the flag position, the body of the hydraulic actuator must travel a significant distance, which necessitates increasing the number of weights and thus considerably increasing the volume of the module to accommodate such a safety system. The large number of weights also significantly increases the mass of the module.

[0013] Furthermore, a blower module comprising a hub centered on the module axis and variable-pitch blades regularly distributed around the hub is known from document FR-A1-3 046 408. The blower module further comprises a blade pitch-changing system including a hydraulic actuator located in a fixed reference frame of the module. According to this document, the hydraulic actuator is therefore fixed in rotation around the axis of the module as opposed to a hydraulic actuator in a rotating frame of reference, that is to say fixed in rotation to the hub.

[0014] According to this document, the module further includes a blade stall safety system in case of hydraulic actuator failure. The safety system includes at least one safety device comprising a movable ring-shaped safety member that rotates around the body of the hydraulic actuator and is capable of cooperating with the body of the hydraulic actuator to move and lock the body of the hydraulic actuator in a position in which the hydraulic actuator forces the blades into a flagging position.

[0015] According to this document, the safety system further includes a rotation drive device for the safety element and a control device for the displacement device configured to detect a failure of the hydraulic actuator and to actuate the displacement device upon detection of this failure.

[0016] Such a blower module is distinct from configurations in which the hydraulic actuator is mobile in rotation around the module's axis. Indeed, such a blower module requires a motion transfer system consisting of a ring, also known by the acronym LTB (for "Load Transfer Bearing"), which transfers the motion from the hydraulic actuator located in a fixed frame of reference to the blades located in a rotating frame of reference, unlike configurations in which the hydraulic actuator is in a rotating frame of reference, thus eliminating the need for such a transfer mechanism.

[0017] Furthermore, in the event of a failure of this ring, no safety position of the blade pitch change system can be ensured and thus adds a constraint to the reliability of this system.

[0018] Moreover, the safety system taught for such a module implies an oversizing of the safety device's drive mechanism, which is incompatible with the size of the blower module.

[0019] Finally, such a safety system is not applicable to a blower module in which the hydraulic actuator is rotationally mobile. Indeed, the safety device would be subjected to a centrifugal force far too great to be integrated into such a blower module.

[0020] In this context, there is a need to provide a variable pitch blade blower module comprising a mobile actuator rotating around the longitudinal axis of the module and in which the blade pitch safety system is lightweight, compact and reliable. Summary of the invention

[0021] To this end, the invention proposes a fan module for an aircraft turbomachine, the fan module having a longitudinal axis and comprising:

[0022] - a hub centered on the longitudinal axis,

[0023] - blades with variable pitch regularly distributed around the hub and presenting each with a pivot point,

[0024] - a blade pitch adjustment system comprising an integral actuator in rotation of the hub and configured to drive the blades in rotation around their pitch axes, the actuator comprising a casing centered on the longitudinal axis and a body connected to the blades, the body being movable in translation along the longitudinal axis in a flag position in which it imposes a flag position on the blades and a pitch position in which it imposes a pitch on the blades different from the flag position, and

[0025] - a blade locking safety system.

[0026] The module is notable in that the security system includes:

[0027] - at least one safety device comprising a movable safety member in translation along the longitudinal axis,

[0028] the safety device being movable between:

[0029] a first position in which the actuator body is free to move between its flag and stall positions, and

[0030] a second position in which the actuator body is driven towards the flag position and free to move along a limited stroke relative to a defined stroke between the flag and stall positions,

[0031] - a drive device for translating the safety component along the axis longitudinal, and

[0032] - a control device for the drive device configured to detect an actuator failure and to actuate the drive device upon detection of this failure so that the safety device is moved from its first to its second position.

[0033] The safety system according to the invention therefore comprises a safety device that moves in translation along the longitudinal axis and is driven by a drive device controlled by a control device.

[0034] The control device detects an actuator failure and activates the drive mechanism. The drive mechanism then causes the safety element to move in translation. This movement of the safety element causes the hydraulic actuator body to move to its flagging position, thus enabling the blades to reach the flagging position.

[0035] Thanks to such a safety system, it is therefore possible to allow a flag position of the blades in a controlled and reliable manner.

[0036] Also, such a safety system makes it possible to do away with the weights and therefore to reduce the total mass of the module and its size.

[0037] Also, such a safety system is compatible with the hydraulic actuator located in a rotating reference frame.

[0038] The module according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0039] — the actuator is a hydraulic actuator,

[0040] — in the second position, the safety device forms a stop limiting the stroke of the actuator body,

[0041] - the safety device is rotationally fixed to the actuator,

[0042] - the safety device comprises a screw and a nut mounted around the screw, the nut forming the safety device and being movable in translation under the effect of a rotation of the screw,

[0043] - the safety device comprises a screw and a nut mounted around the screw, the screw forming the safety mechanism and being movable in translation under the effect of a rotation of the nut,

[0044] - the nut is a ball nut and comprises balls cooperating with a thread external part of the screw,

[0045] - the drive device includes an electric motor fixed in rotation to the actuator,

[0046] - the drive device further comprises a transformer or generator,

[0047] - the security system comprises a plurality of security devices, advantageously between 2 and 10 safety devices distributed circumferentially around the longitudinal axis,

[0048] - the drive device comprises a plurality of electric motors configured respectively to drive the safety components of the plurality of safety devices,

[0049] - the transformer comprises a stator centered on the longitudinal axis and a rotor arranged coaxially around the stator, with the motors evenly distributed around the transformer rotor,

[0050] - the body is mobile in translation along the longitudinal axis inside the envelope in a thrust reversal position in which it imposes a thrust reversal position on the blades,

[0051] - the safety device is movable in translation along the longitudinal axis in a third position in which it allows the hydraulic actuator body to be in its thrust reversal position, and

[0052] - the control device is configured to actuate the drive device so that the safety device is moved to the third position. Brief description of the figures

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

[0054] [Fig-1] [Fig.1] is a schematic representation of a half turbomachine aircraft to which the invention applies;

[0055] [Fig.2] [Fig.2] is a schematic representation of a blower module according to the invention equipping the turbomachine of [Fig.l];

[0056] [Fig.3] [Fig.3] is a kinematic diagram of the safety device equipping the module of the [Fig.2],

[0057] [Fig.4] [Fig.4] is a longitudinal cross-sectional view of a safety device equipping the module of [Fig.2],

[0058] [Fig. 5] [Fig. 5] is a schematic cross-sectional view of a device training of a safety component of the safety device of the [Fig.4]. Detailed description of the invention

[0059] An aircraft comprises a fuselage and at least two wings extending from either side of the fuselage along the fuselage axis. At least one turbomachine 1 is mounted, for example, under each wing.

[0060] To facilitate its manufacture, assembly, mounting, and disassembly, the turbomachine 1 is modular, meaning that it comprises several modules that are manufactured independently of each other and then assembled together. The modularity of the turbomachine 1 also facilitates its maintenance.

[0061] Such a turbomachine 1 is illustrated for example by [Fig. 1]. The turbomachine 1 has a longitudinal axis X.

[0062] In the present application, the terms "axial", "axially", "radial" and "radially" are defined with respect to the longitudinal axis X. The terms "upstream", "downstream" are defined with respect to the direction of gas flow in the turbomachine 1 along the longitudinal axis X. The terms "internal", "inside", "external", "outside", "externally" are defined with respect to the distance from the longitudinal axis X along a radial axis perpendicular to the longitudinal axis X.

[0063] The turbomachine 1 includes a gas generator 2 and a blower module 3 arranged for example upstream of the gas generator 2.

[0064] The gas generator 2 typically comprises, from upstream to downstream, a low-pressure compressor 4, a high-pressure compressor 5, a combustion chamber 6, a high-pressure turbine 7, and a low-pressure turbine 8. The compressor rotors The rotors of the low-pressure compressor 4 and the low-pressure turbine 8 are mechanically connected by a low-pressure shaft 9 to form a low-pressure unit. The rotors of the high-pressure compressor 5 and the high-pressure turbine 7 are mechanically connected by a high-pressure shaft 10 to form a high-pressure unit. The high-pressure shaft 10 is arranged coaxially around the low-pressure shaft 9.

[0065] The high-pressure body is guided in rotation about the longitudinal axis by a first upstream bearing 11 and a second downstream bearing 12. The first bearing 11 is mounted radially between an inter-compressor housing 13 and an upstream end of the high-pressure shaft 10. The inter-compressor housing 13 is arranged axially between the low-pressure compressor 4 and the high-pressure compressor 5. The second bearing 12 is mounted radially between an inter-turbine housing 14 and a downstream end of the high-pressure shaft 10. The inter-turbine housing 14 is arranged axially between the low-pressure turbine 7 and the high-pressure turbine 8.

[0066] The low-pressure body is guided in rotation about the longitudinal axis X via a third bearing 15 and a fourth, preferably double, bearing 16. These are mounted radially between an exhaust housing 17 and a downstream end of the low-pressure shaft 9. The exhaust housing 17 is located downstream of the low-pressure turbine 8. The third bearing 15 is mounted radially between an inlet housing 18 and an upstream end of the low-pressure shaft 9. The inlet housing 18 is arranged axially between the blower module 3 and the low-pressure compressor 4.

[0067] According to the example in [Fig. 1], the fan 3 comprises, for example, a fan casing 19 which carries a nacelle 20. The fan 3 is of the enclosed type. The turbomachine 1 is, according to this example, a turbojet engine.

[0068] According to another example not shown, the fan 3 is unducted (open rotor, USF for Unducted Single Fan or UDF for Unducted Fan). The turbomachine 1 is, in this example, a turboprop. Of course, the invention applies to other types of turbomachinery.

[0069] The blower 3 compresses an airflow F which splits into a primary airflow Fl and a secondary airflow F2 at a separation nozzle 21. The latter is carried by the inlet housing 18 centered on the longitudinal axis X. The inlet housing 18 is extended downstream by an inter-vein housing 22. The primary airflow Fl flows in a primary vein 23 which passes through the gas generator 2 and exits through a primary nozzle 24.

[0070] The secondary airflow F2 circulates in a secondary vein 25 and escapes from it through a secondary nozzle 26 of the nacelle 20. The primary vein 23 and the secondary vein 25 are separated by the inter-vein housing 22.

[0071] The blower module 3 comprises a series of blades 30 extending radially around a hub 31. The hub 31 is movable in rotation about the longitudinal axis X. It is driven in rotation by a blower shaft 32 centered on the longitudinal axis X.

[0072] The blower shaft 32 is driven in rotation by a power transmission shaft with longitudinal axis X via a power transmission mechanism 33. In the present example, the power transmission shaft is the low pressure shaft 9. The blower shaft 32 and the low pressure shaft 9 are coaxial.

[0073] The power transmission mechanism 33 is, for example, a mechanical speed reducer 34 that reduces the rotational speed of the blower shaft 32 relative to the speed of the low-pressure shaft 9. Furthermore, the speed reducer 34 allows for the arrangement of a blower module 3 with a large diameter in order to increase the dilution ratio. The reducer 34 is of the planetary gear train type. It is housed in a lubrication chamber 35 in which it is lubricated. The lubrication chamber 35 is, for example, located inside the inlet housing 18. Typically, the speed reducer 34 comprises a sun gear 36 (or inner planet gear), planet gears 37, a planet carrier 38, and an outer ring gear 39 (or outer planet gear). In this example, the solar 36 is centered on the longitudinal axis X and is rotationally coupled with the power shaft along the longitudinal axis X.The satellites 37 are carried by the satellite carrier 38 and each rotates around an axis substantially parallel to the longitudinal axis X. Each of the satellites 37 meshes with the solar element 36 and the outer ring 39. The satellites 37 are arranged radially between the solar element 36 and the outer ring 39. The outer ring 39 is rotationally coupled with the blower shaft 32. The ring 39 is centered on the longitudinal axis X. Thus, the solar element 36 forms the input of the speed reducer 34 while the outer ring 39 forms its output. The planet carrier 38, on the other hand, is fixed relative to the ring 39. The planet carrier 38 is in particular fixed to a fixed structure of the turbomachine 1 via a support ferrule 40. The latter is fixed to the inlet casing 18 of the turbomachine 1. The support ferrule 40 is also fixed to a first bearing support 41, fixed, integral with the inlet casing 18.The first bearing support 41 is installed downstream of the speed reducer 34. Alternatively, the planet carrier 38 is fixed on a radially internal ferrule of the input housing 18 or directly on a second bearing support 44 arranged upstream of the speed reducer 34.

[0074] The third bearing 15 is mounted downstream of the speed reducer 34. A fifth bearing 42 is arranged upstream of the reducer 34, and a sixth bearing 43 is arranged upstream of the fifth bearing 42. The outer rings of these The bearings are supported by the second bearing support 44. The internal rings are integral with the blower shaft 32.

[0075] According to the invention, the blower module 3 comprises variable-pitch blades 30. Each blade 30 comprises a foot 45 and a body 46 extending radially outwards from the foot 45. In the example of this Figure 1, the blades 30 are surrounded by the blower housing 19.

[0076] The body 46 of each blade 30 has an aerodynamic shape. It comprises a leading edge and a trailing edge connected by an intrados face and an extrados face.

[0077] The foot 45 and the body 46 may be made from a single piece of material or separate. In the latter case, the body 46 fits into the foot 45 via a dovetail joint, for example. The hub 31 is centered on the longitudinal axis X and includes several recesses 47 distributed regularly around the longitudinal axis X. Each recess 47 receives the foot 45 of a blade 30. There are thus as many recesses as there are feet 45.

[0078] The foot 45 of each blade 30 is pivotally mounted about a shim C in the hub 31. The shim C extends radially with respect to the longitudinal axis X. The foot 45 is pivotally mounted by means of at least two guide bearings (not shown) mounted in each housing 47 and in a superimposed manner along the shim C. These bearings are preferably, but not exclusively, roller bearings.

[0079] In order to modify the pitch of the blades 30 according to the flight phases of the aircraft, the fan module 3 further includes a blade pitch change system 50. The change system 50 is arranged in particular upstream of the speed reducer 34. The change system 50 includes an actuator 52 configured to drive the blades 30 around their pitch axes C. Advantageously, the change system 50 also includes a linkage mechanism 51 connected to the blades 30 and to the actuator 52.

[0080] The actuator 52 is arranged upstream of the speed reducer 34. The actuator 52 comprises an annular housing 53 and a body 54 movable in translation along the longitudinal axis X. Advantageously, the body 54 is movable in translation inside the housing 53. Advantageously, but not limitingly, the actuator 52 is a linear cylinder centered on the longitudinal axis X.

[0081] The actuator 52 is of the reversible type.

[0082] The actuator 52 is free to rotate about the longitudinal axis X. It is therefore in a rotating frame of reference of the blower module 3. According to the invention, the actuator 52 is rotationally fixed to the hub 31. In the example shown in [Fig. 1], the hub 31 is connected to the blower shaft 32 via a blower cone 59. The latter is rotationally fixed to the blower shaft 32 and the casing 53. For this purpose, the blower cone 59 includes a radial flange 60 which is attached to the casing 53 and the blower shaft 32. The blower cone 59 also includes a radial tab which is attached to a downstream side of the hub 31. Attaching the blower cone 59 downstream of the hub 31 allows the connecting mechanism 51 to be integrated upstream and reduces the axial footprint of the blower module 3.

[0083] By advantageously linking the casing 53 to the hub 31, the forces transmitted from the hub 31 to the actuator 52 are limited. The force path passes directly from the blower cone 59 to the blower shaft 32 and to the guide bearings 42, 43 of the blower shaft 32.

[0084] The casing 53 is centered on the longitudinal axis X, and has an overall circular cross-section. This configuration makes it possible to limit the size of the actuator 52 in the blower module 3 both axially and radially.

[0085] As more clearly seen in [Fig. 2], the body 54 is in the form of a rod comprising an upstream axial end 54a and a downstream axial end 54b. The downstream axial end 54b includes a piston 54c which delimits two fluid receiving chambers inside the casing 53. The upstream axial end 54a has a first axial stop 54d. The axial stop 54d extends radially outwards from the body 54. The axial stop 54d is located outside the casing 53.

[0086] The body 54 moves axially within the envelope 53 and occupies at least two extreme positions in which it imposes a flagging position and a thrust reversal position on the blades 30, respectively. The body 54 can occupy any position between these two extreme positions depending on the different flight phases of the aircraft. One of the axial positions of the body 54 is a flagging position, which therefore corresponds to a position in which it imposes a flagging position on the blades 30, and another position, called the pitching position, is an axial position of the body 54 in which it imposes a pitch on the blades 30 that differs from the flagging and thrust reversal positions. The body 54 can occupy another position, called the thrust reversal position, in which it imposes a thrust reversal position on the blades 30, known in English as "reverse".The positioning of body 54 is therefore an intermediate axial position of body 54 located between the flag and thrust reversal positions of body 54.

[0087] The body 54 is advantageously connected to the blades 30 by means of the linkage mechanism 51. The translational movement of the body 54 along the longitudinal axis X causes the linkage mechanism 51 to move, such that the latter causes the pivoting and pitching of the blades 30 around the pitching axis C. In the example of Figures 1 and 2, the linkage mechanism comprises an annular part 74 connected to the actuator 52 and connecting rods 82 connecting the annular part 74 to the blades 30.

[0088] The annular part 74 includes a proximal portion 75 which is integral with the body 54 of the actuator 52. The annular part 74 further includes a central portion 77 which has a first end connected to the proximal portion 75 and which extends downstream by flaring out and a second end connected to the connecting rods 82. The central portion 77 has a substantially frustoconical axial section.

[0089] Each connecting rod 82 comprises a first end and a second end opposite each other along the elongation direction of the connecting rod 82. The elongation direction is substantially parallel to the longitudinal axis X. The first ends of the connecting rods 82 are connected to the annular part 74. The connecting rods 82 are made of a metallic material. There are as many connecting rods as there are blades 30.

[0090] Advantageously, the body 54 moves axially under the effect of the pressure of a fluid circulating in the chambers of the actuator 52. The fluid is, for example, a pressurized hydraulic fluid, such as oil. To this end, with reference to [Fig. 1], the turbomachine 1 includes a fluid supply system 90 for the actuator 52. The fluid supply system 90 includes a supply source 91, a hydraulic pump 92 for circulating the fluid to the actuator 52 from the supply source 91, and optionally a servovalve 93 for regulating the fluid pressure in the actuator 52 according to the required timing. The servovalve 93 is electrically controlled by an electronic control unit 27 of the turbomachine 1, which is known as the "ECU" for "Electronic Control Unit".

[0091] The fluid supply system 90 also includes several supply pipes 95 to convey the fluid to the actuator 52. The pipes 95 pass through the planet carrier 38 and are connected to the servovalve 93. Since the planet carrier 38 is fixed against rotation, it allows the pipes 95 to pass through it and also inside the blower shaft 32. The supply source 91 is arranged in a fixed location on the turbomachine 1 and generally in the nacelle 20 or in the inter-flow housing 22. The pump 92 and the servovalve 93 are also arranged in the fixed location on the turbomachine 1.

[0092] Since, according to the invention, the actuator 52 is in a rotating frame, the blower module 3 advantageously comprises a fluid transfer device 94 enabling the transfer of fluid from the fixed frame to the rotating frame. This transfer device 94 is known by the English acronym "OTB" for "Oil Transfer Bearing". The fluid transfer device 94 is arranged upstream of the speed reducer 34. The location of the fluid transfer device 94 is advantageous because it facilitates its removal / installation without requiring any intervention on the speed reducer 34.

[0093] The transfer device 94 extends inside the blower shaft 32 so as to reduce the axial and radial dimensions. The transfer device 94 is located inside the actuator 52.

[0094] The transfer device 94 includes fluid communication means on the one hand with the power source 91 and on the other hand with the actuator 52. The transfer device 94 comprises a stator portion and a rotor portion. One of the stator and rotor portions is engaged within the other so as to reduce the overall size and form a compact assembly that is easy to mount and dismount. The stator portion is rigidly mounted to a fixed structure of the turbomachine. In the present example, the stator portion is attached to the planet carrier 38. The pipes 95 are connected to the fluid transfer device 94 in order to transfer the fluid from the stator portion to the rotor portion.

[0095] In the event of a failure of the actuator 52 or the fluidic supply system 90, it is necessary to be able to secure the blades 30 in the feathered position. To this end, the blower module 3 according to the invention further includes a safety system 96 for locking the blades 30. The safety system 96 comprises at least one safety device 97, a drive device 98, and a control device 99. The safety system 96 is arranged upstream of the actuator 52.

[0096] Advantageously, the safety system 96 comprises a plurality of safety devices 97. Even more advantageously, the safety system 96 comprises between 2 and 10 safety devices 97 regularly distributed around the longitudinal axis X.

[0097] Each safety device 97 is arranged upstream of the actuator 52. Each safety device 97 is in the rotating reference frame of the blower module 3. Each safety device 97 is advantageously rotationally fixed to the actuator 52.

[0098] Each safety device 97 comprises a safety member that is movable in translation along the longitudinal axis X. The safety member is movable between a first position P1 in which the body 54 of the actuator 52 is free to move between its flag and stall positions, and a second position P2 in which the body 54 of the actuator 52 is driven towards its flag position and is free to move along a limited stroke relative to a defined stroke between the flag and stall positions. In this second position P2 of the safety member, the body 54 of the actuator 52 cannot move into the thrust reversal position. The safety member is movable in a third position P3 in which it allows the body 54 of the actuator 52 to be in its thrust reversal position, which forces the thrust reversal position on the blades 30.

[0099] The PI position of the safety device is an axial position located between positions P2 and P3. Position P3 is the downstream position compared to positions PI and P2, and position PI is the upstream position compared to positions P2 and P3.

[0100] The first axial stop 54d is arranged upstream or downstream of the safety device.

[0101] Advantageously, each safety device 97 is of the screw-nut type. It comprises a nut 100 and a screw 101 around which the nut 100 is mounted coaxially. As more clearly seen in [Fig. 4], the screw 101 has a central axis Y that extends parallel to the longitudinal axis X of the blower module 3. The screw 101 advantageously extends between an axially opposed upstream end 101a and downstream end 101b. The upstream end 101a is connected to the drive device 98, and the nut 100 is mounted on the downstream end 101b. The screw 101 also has an external thread advantageously extending from the upstream end 101a to the downstream end 101b. The screw 101 is for example mounted inside an external cylinder 101' which is rotationally fixed to the actuator 52.

[0102] The nut 100 has a passage for the screw 101. According to a particularly advantageous embodiment of the invention, the safety device 97 is of the ball screw type. According to this embodiment, the nut 100 further comprises balls 102 cooperating with the external thread of the screw 101. Advantageously, the nut 100 comprises a plurality of rows of balls 102, each cooperating with the external thread 101 of the screw 101.

[0103] According to a first embodiment illustrated in [Fig.2], the safety device is formed by the nut 100. According to this embodiment, the screw 101 is free to rotate about its central axis Y and the nut 100 is fixed to rotate about the central axis Y of the screw 101. The rotation of the screw 101 has the effect of driving the nut 100 in translation along the longitudinal axis X.

[0104] According to a second embodiment not shown, the safety device is formed by the screw 101. According to this embodiment, the nut 100 is free to rotate about the central axis Y of the screw 101 and the screw 101 is fixed to rotate about its central axis Y. The rotation of the nut 100 has the effect of driving the screw 101 in translation along the longitudinal axis X.

[0105] The drive device 98 enables the safety element to be driven in translation along the longitudinal axis X of each safety device 97. The drive device 98 comprises at least one electric motor 103 for driving the safety element in translation along the longitudinal axis X. Advantageously, the drive device 98 comprises a plurality of electric motors 103, each electric motor 103 driving the safety elements respectively. Therefore, there are as many electric motors 103 as there are safety devices 97.

[0106] Each electric motor 103 is advantageously mounted upstream of the safety device 97. Each electric motor 103 is rotationally fixed to the safety device 97 and therefore to the actuator 52. Each electric motor 103 is, for example connected to the upstream end 101a of the screw 101 for its rotational drive around the nut 100. Advantageously, each electric motor 103 is connected to its respective screw 101 by a reduction gear 103'. Each electric motor 103 is supplied with electrical energy E from an electrical energy source S located, for example, in the turbomachine 1. The electrical energy source S is, for example, located in a fixed frame of reference of the turbomachine 1.

[0107] The drive device 98 includes a transformer or generator 104 to supply electrical energy to each electric motor 103.

[0108] The generator 104 transforms the mechanical energy extracted, for example, from the high-pressure shaft 10 into electrical energy. The advantage of the generator 104 is that it does not require the routing of electrical cables.

[0109] The transformer 104 allows the transfer of electrical energy E from the source S located in a fixed frame to the electric motor 103 located in a rotating frame.

[0110] With reference to [Fig. 5], the transformer 104 comprises a rotor 104a and a stator 104b. The rotor and stator 104a, 104b are coaxial and centered on the longitudinal axis X. Advantageously, the rotor 104a is located around the stator 104b. The stator 104b is, for example, connected to the input housing 18 and the rotor 104a is, for example, connected to the hub 31. The transformer 104 ensures the transfer of electrical energy E by electromagnetic induction, for example.

[0111] Advantageously, the electric motors 103 are regularly distributed around the rotor 104 of the transformer 104.

[0112] According to another example not shown, each electric motor 103 is powered by a supply coil.

[0113] The control device 99 controls the drive device 98. The control device 99 is configured to detect a failure of the actuator 52 and to actuate the drive device 98 upon detection of this failure, so that the safety element is moved from its first position P1 to its second position P2 or its third position P3. The control device 99 is typically controlled by the electronic control unit 27. The electronic control unit 27 sends a non-feathering signal to the control device 99. In the event of a failure of the actuator 52, no signal is transmitted, and the control device 99 then actuates the drive device 98. The electronic control unit 27 sends a signal by radio wave or by commutator brushes, for example.

[0114] An example of the operation of the security system 96 will now be described.

[0115] In normal operation of the actuator 52, the safety device is in the PL position

[0116] When the actuator 52 fails due to a rupture, for example, of the fluid supply system 90, the electronic control unit 27 breaks the signal The control device 99 detects the absence of a feathering signal and then activates the drive device 98, which is then supplied with electrical energy E. Each motor 103 then drives the translational movement of the safety device along the longitudinal axis X from position PI to position P2. During this translational movement, the safety device interacts with the first axial stop 54d and causes the body 54 of the actuator 52 to move in a translational direction towards its feathering position. The safety device then limits the stroke of the body 54 relative to the stroke between the feathering and stalling positions, and the body 54 can thus force the blades 30 into a feathering position. In this position of the safety device, the body 54 cannot allow, for example, a thrust reversal position for the blades 30.

[0117] Thanks to the safety system 96 according to the invention, it is possible to do without weights and thus reduce the size of the blower module 3. Also, the safety system 96 makes it possible to reduce the total mass of the blower module 3. A mass saving of 70% can be obtained compared to the use of weights.

[0118] Furthermore, thanks to the control device 99, it is possible to allow a flag position of the blades 30 in a controlled and reliable manner.

[0119] In addition, it is possible to control the actuation of the safety system 96 only when needed, which reduces the fatigue of the safety system 96.

[0120] Moreover, thanks to the advantageous embodiment of the safety device 97 in the form of a screw and nut and in particular of ball screws, it is possible to generate a significant torque.

[0121] Thanks to the advantageous realization module in which the security system includes a plurality of 97 security devices, it is possible to provide a significant force for flagging.

Claims

1. Demands Fan module (3) for an aircraft turbomachine (1), the fan module (3) having a longitudinal axis (X) and comprising: - a hub (31) centered on the longitudinal axis (X), - blades (30) with variable pitch regularly distributed around the hub (31) and each having a pitch axis (C), - a system for changing the pitch of the blades (30) comprising an actuator (52) rotationally fixed to the hub (31) and configured to drive the blades (30) in rotation about their pitch axes (C), the actuator (52) comprising a housing (53) centered on the longitudinal axis (X) and a body (54) connected to the blades (30), the body (54) being movable in translation along the longitudinal axis (X) in a flag position in which it imposes a flag position on the blades (30) and a pitch position in which it imposes a pitch on the blades (30) different from the flag position, and - a blade locking safety system (96), characterized in that the safety system (96) comprises: - at least one safety device (97) rotationally fixed to the actuator (52) and comprising a safety member movable in translation along the longitudinal axis (X), the safety member being movable between: a first position (PI) in which the body (54) of the actuator (52) is free to move between its flag and stall positions, and a second position (P2) in which the body (54) of the actuator (52) is driven towards the flag position and free to move along a limited stroke relative to a defined stroke between the flag and stall positions, - a drive device (98) for translating the safety component along the longitudinal axis (X), and - a control device (99) of the drive device (98) configured to detect a failure of the actuator (52) and to actuate the drive device (98) upon detection of this failure so that the safety element is moved from its first to its second position (PI, P2), the safety device (97) comprising a screw (101) and a nut (100) mounted around the screw (101).

2. Module according to any one of the preceding claims, characterized in that the nut (100) forms the safety element and is movable in translation under the effect of a rotation of the screw (101).

3. Module according to claim 1, characterized in that the screw (101) forms the safety element and is movable in translation under the effect of a rotation of the nut (100).

4. Module according to any one of claims 1 to 3, characterized in that the nut (100) is a ball nut and comprises balls (102) cooperating with an external thread of the screw (101).

5. Module according to any one of the preceding claims, characterized in that the drive device (98) comprises an electric motor (103) rotationally fixed to the actuator (52).

6. Module according to the preceding claim, characterized in that the drive device (98) further comprises a transformer or generator (104).

7. Module according to any one of the preceding claims, characterized in that the safety system (96) comprises a plurality of safety devices (97), advantageously between 2 and 10 safety devices (97) distributed circumferentially around the longitudinal axis (X).

8. Module according to the preceding claim, characterized in that the drive device (98) comprises a plurality of electric motors (103) configured respectively to drive the safety members of the plurality of safety devices (97).

9. Module according to the preceding claim in combination with claim 6, characterized in that the transformer (104) comprises a stator (104b) centered on the longitudinal axis (X) and a rotor (104a) arranged coaxially around the stator (104b), the motors (103) being regularly distributed around the rotor (104a) of the transformer (104).

10. Module according to any one of the preceding claims, characterized in that: - the body (54) is movable in translation along the longitudinal axis (X) inside the casing (53) in a thrust reversal position in which it imposes a thrust reversal position on the blades (30), - the safety device is movable in translation along the longitudinal axis (X) in a third position (P3) in which it allows the body (54) of the hydraulic actuator (52) to be in its thrust reversal position, and - the control device (99) is configured to actuate the drive device (98) so that the safety device is moved to the third position (P3).

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