Fan rotor with actuator with locking device

Abstract

The invention relates to a fan rotor comprising an actuator with an actuating cylinder and a locking device capable of immobilising a movable portion of the actuating cylinder. This locking device comprises a notched surface (162), a blocking member (164) having an unlocked configuration spaced apart from the surface (162) and a locked configuration engaged with the surface (162), a movable member (200) that is movable between a retracted position in which it leaves the blocking member (164) free to be in its unlocked configuration and a deployed position in which it forces the blocking member (164) into its locked configuration, a return member (220) that urges the movable member (200) towards its deployed position and a holding device (222) for holding the movable member (200) in its retracted position.

Description

[0001] DESCRIPTION

[0002] TITLE: BLOWER ROTOR WITH ACTUATOR WITH LOCKING DEVICE

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to the general field of actuators comprising a cylinder and a device for locking the movable part of the cylinder. It relates more particularly to the field of actuators intended for controlling the orientation of variable-pitch blades such as those equipping the fans of certain turbomachines.

[0005] A preferred field of application of the invention is that of turbojets with unducted fans (better known under the English names "propfan", "open fan", "open rotor" and "unducted fan"). However, the invention also applies to turboprops with one or more pusher propellers.

[0006] TECHNOLOGICAL BACKGROUND

[0007] One of the avenues currently being explored to improve the specific consumption of civil aircraft engines is the development of unducted fan turbojets, such as that described in document FR 2 941 493. These turbojets comprise a conventional turboshaft gas generator, one or more turbine stages of which drive one or more unducted fans extending outside the engine nacelle.

[0008] The blades of this or these fans are, as in the case of conventional turboprops, variable pitch, that is to say that the angular position of these blades (called the pitch angle) can be modified during flight. As a reminder, the pitch angle of a blade corresponds to the angle, in a plane orthogonal to the pivot axis of the blade, between the rotation axis of the fan and the chord of the blade at 75% of the radius of the fan. It can vary from a value equal to 90°, corresponding to a so-called "sail" or "flat" position of the blade, to a value equal to 0°, corresponding to a so-called "flag" position of the blade. It can also take a value strictly greater than 90°, typically substantially equal to 95°, corresponding to a so-called "reverse" position of the blade.As is known, this modification of the pitch angle during flight makes it possible to change the engine thrust and optimize the efficiency of the fan according to the aircraft speed. Indeed, the fan speed is almost constant during all phases of operation, and it is the pitch of the blades that varies the thrust. Thus, in the cruise flight phase, the blades are oriented so as to adjust the thrust by minimizing the power taken from the turbine shaft and consumption and by optimizing efficiency. Conversely, during takeoff, the blades are oriented so as to maximize the thrust in order to accelerate and then take off the aircraft.

[0009] The control of the orientation of the blades is commonly carried out by means of a pitch change mechanism comprising a control cylinder having a part which moves in translation along the axis of the fan and a connection system connecting the moving part to the blade so as to convert the translation of the moving part into rotation of the variable-pitch blade.

[0010] A difficulty encountered with variable pitch blades is that, in the event of a malfunction in the systems controlling their orientation, the blades tend, under their own centrifugal effect, to move into the sail position. However, a blade stuck in this position generates little resistive torque and risks causing the engine to overspeed, with potential risks of engine damage. In addition, a blade stuck in this position also risks generating excessive drag that is unacceptable for the aircraft's controllability and / or its range in the case of a diversion mission.

[0011] To overcome this difficulty, it is known to use safety systems capable of preventing the movement of the variable pitch blades towards small pitches (i.e. towards the sail position) in the event of failure of the blade orientation control system. Such a system is known, for example, from EP 3 400 169.

[0012] In particular, a safety system is known which integrates into the actuator controlling the orientation of the blades a screw-nut system of the ball screw type coupled to a locking nut. In normal operation, the nut of the screw-nut system follows the movements of the control actuator, thus causing the rotation of the screw around its axis, while the locking nut follows the thread of the screw without ever touching it (the tapping of the locking nut is designed to provide a slight clearance with the thread of the screw). In the event of a malfunction of the blade orientation control system, the screw of the screw-nut system is immobilized (its rotation is blocked) and the locking nut engages with said screw, thus preventing the pivoting of the blades towards the small pitches.

[0013] This safety system is not, however, entirely satisfactory. In fact, for it to work properly, it requires precise and complex management of the clearances between the locking nut and the screw thread. DISCLOSURE OF THE INVENTION

[0014] One objective of the invention is to enable, in a simple and robust manner, the locking of a cylinder in at least one direction. Other objectives are to enable the locking of the cylinder in its current position (with a certain tolerance), to enable locking in the absence of power supply to the cylinder, to enable locking and / or unlocking with a low force, to enable locking that is resistant to very high loads, and to limit the size of the locking mechanism.

[0015] To this end, the invention relates, according to a first aspect, to an actuator comprising: a control cylinder comprising a fixed part and a movable part movable in translation along a longitudinal axis relative to the fixed part, and a locking device capable of blocking the translation of the movable part relative to the fixed part in at least one direction, in which the locking device comprises: a surface secured to the fixed part or movable jointly with the movable part relative to the fixed part, the surface being notched with a plurality of notches each extending orthogonally to the longitudinal axis, a locking member having an unlocking configuration away from the surface and a locking configuration engaged with the surface so that the movable part is immobilized in translation relative to the fixed part, in which the locking member is engaged in at least one of said notches,a movable member movable in translation relative to the locking member between a retracted position in which it leaves the locking member free to be in its unlocking configuration and a deployed position in which it forces the locking member into its locking configuration, a return member urging the movable member towards its deployed position, and a holding device for holding the movable member in its retracted position under certain predetermined conditions.,

[0016] According to particular embodiments of the invention, the actuator also has one or more of the following characteristics, taken in isolation or in any technically possible combination(s): the predetermined conditions consist of a supply pressure of the chambers of the control cylinder greater than a threshold; said threshold is lower than a minimum supply pressure of the chambers of the control cylinder under normal operating conditions; the holding device comprises a counterbalancing cylinder with a counterbalancing chamber in contact with a piston secured to the movable member, capable of receiving a pressurized fluid to counterbalance the stress of the return device; the surface is movable jointly with the movable part relative to the fixed part and is preferably secured to the movable part, the locking member being substantially fixed along the longitudinal axis relative to the fixed part;the surface comprises, for each pair of consecutive notches, a rib separating said notches, said rib having inclined sides, said sides having a maximum inclination preferably less than 88°, in particular less than 60°, for example less than 45°; the rib has a rounded top; each notch has a rounded bottom, the transition from a rib top to a notch bottom, via a rib side, taking place without breaking the slope;the locking member comprises at least one ring arranged orthogonally to the longitudinal axis, said ring being circumferentially divided into several sectors movable relative to each other between a close configuration, in which the ring has a reduced diameter, and a spaced configuration, in which the ring has an increased diameter, the locking member being in the locking configuration when the ring is in one of the spaced and close configurations and in the unlocking configuration when the ring is in the other of the spaced and close configurations; the or each ring is, in the locking configuration, engaged in only one of the notches of the surface; the or each ring comprises a return element urging the sectors towards that of the spaced and close configurations in which the locking member is in the unlocking configuration; each sector has a circular or ovoid section;each sector has a polygonal section; each sector comprises two flanks delimiting the sector in the longitudinal direction, said flanks converging towards each other in the direction of the surface; the flanks are substantially symmetrical with respect to a plane orthogonal to the longitudinal axis and form between them an angle of between 4° and 90°, in particular greater than 60°; the locking member has a first face oriented towards the surface and a second face opposite the first face, and the movable member comprises a retaining face capable of being in contact with the second face of the locking member in the locking configuration; the second face has a contact edge by which the movable member comes into contact with the locking member when it moves from its retracted position to its deployed position, said contact edge being beveled;the movable member has at least one contact face through which it comes into contact with the locking member when it moves from its retracted position to its deployed position, said contact face being beveled and / or provided with at least one bearing; for the or each contact face, at least one bearing is located at a junction between the contact face and the retaining face; the movable member has a contact face for each ring of the locking member, said contact face forming a face through which the movable member comes into contact with said ring when it moves from its retracted position to its deployed position; the locking device comprises an elastic sheath between the surface and the fixed part, said elastic sheath isolating the surface from the environment; the surface is interposed between the longitudinal axis and the locking member;and the surface is cylindrical and the locking member extends around said surface. The invention also relates, according to a second aspect, to a fan rotor for a turbomachine comprising a hub and a plurality of variable-pitch blades each pivotable relative to the hub around a specific pivot axis, the rotor further comprising an actuator according to the first aspect for adjusting an angular position of each of the variable-pitch blades around its respective pivot axis, the fixed part being fixed relative to the pivot axis, the actuator further comprising a connection system connecting the movable part to the variable-pitch blade so as to convert the translation of the movable part along the longitudinal axis into a rotation of the variable-pitch blade around the pivot axis.;

[0017] According to a particular embodiment of the invention, the fan rotor also has the following characteristic: the longitudinal axis constitutes an axis of rotation of the rotor. The invention also relates, according to a third aspect, to a turbomachine comprising a fan rotor according to the second aspect.

[0018] According to a particular embodiment of the invention, the turbomachine also has the following characteristic: the longitudinal axis constitutes an axis of elongation of the turbomachine.

[0019] Finally, the invention relates, according to a fourth aspect, to an aircraft comprising at least one turbomachine according to the third aspect.

[0020] BRIEF DESCRIPTION OF THE FIGURES

[0021] Other characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of example and with reference to the appended drawings, in which: Figure 1 is a top view of an aircraft according to an exemplary embodiment of the invention, Figure 2 is a simplified longitudinal sectional view of a turbomachine of the aircraft of Figure 1, Figure 3 is a simplified longitudinal sectional view of a part of a pitch change mechanism of the turbomachine of Figure 2, Figure 4 is a simplified view along a radial axis of an arm for rotating a variable-pitch blade of the turbomachine of Figure 2, Figure 5 is a partial simplified longitudinal sectional view of a first variant of a locking device of the pitch change mechanism of Figure 3, in a first configuration, Figure 6 is a view similar to that of Figure 5,the locking device being in a second configuration,

[0022] [Fig. 7] [Fig. 8] Figures 7 and 8 are partial simplified views in longitudinal section of other variations of the locking device of the pitch change mechanism of Figure 3, and

[0023] [Fig. 9] [Fig. 10] Figures 9 and 10 are front views of a locking member of the locking device of Figures 5 and 6.

[0024] DETAILED DESCRIPTION OF AN EXAMPLE OF IMPLEMENTATION

[0025] The aircraft 10 shown in Figure 1 comprises turbomachines 12 to propel it. In the example shown, the aircraft 10 is an airplane. This comprises, in a conventional manner, a fuselage 14, a tailplane 16 and two wings 18. The turbomachines 12 are here two in number and are each housed under a respective wing 18. As a variant (not shown), the turbomachines 12 are arranged along the fuselage 14, for example near the tailplane 16. As a further variant (also not shown), the aircraft 10 comprises a single turbomachine 12 or at least three turbomachines 12.

[0026] One of the turbomachines 12 is shown in Figure 2.

[0027] As visible in this Figure 2, the turbomachine 12 is elongated along a longitudinal axis X. It typically has an angular symmetry around said longitudinal axis X, that is to say that there is at least one angle for which the turbomachine is invariant by rotation around the longitudinal axis X.

[0028] Here and hereinafter, the terms "interior" and "exterior", "internal" and "external", as well as their variations, are understood in reference to the X axis, an element described as "interior" or "internal" being oriented towards the X axis while an "exterior" or "external" element is oriented opposite the X axis.

[0029] The turbomachine 12 comprises, in a conventional manner, a nacelle 20, an internal vein 22 for circulating an air flow through the nacelle 20, a combustion chamber 24 housed in the vein 22, an engine body 26 and a gas exhaust nozzle 28.

[0030] In the following, the terms “upstream” and “downstream” are understood to refer to a direction of flow of an air flow through the vein 22.

[0031] The engine body 26 comprises a compressor 30, a turbine 32 and a transmission shaft 34 coupling the turbine 32 to the compressor 30 for driving the compressor 30 by the turbine 32. The compressor 30 is arranged upstream of the combustion chamber 24 and supplies the combustion chamber 24 with compressed air. The turbine 32 is arranged downstream of the combustion chamber 24 and receives the exhaust gases leaving the combustion chamber 24.

[0032] The transmission shaft 34 has the longitudinal axis X as its axis of rotation.

[0033] The transmission shaft 34 is guided in rotation relative to the nacelle 20 by means of bearings (not shown).

[0034] In the example shown, the turbomachine 12 is a multi-body turbomachine, in particular a double-body turbomachine, comprising a low-pressure body 40 in addition to the engine body 26. The engine body 26 then constitutes a high-pressure body, the compressor 30 being a high-pressure compressor, the turbine 32 being a high-pressure turbine and the transmission shaft 34 being a high-pressure shaft.

[0035] The low pressure body 40 comprises a low pressure compressor 42, a low pressure turbine 44 and a low pressure shaft 46 coupling the low pressure turbine 44 to the low pressure compressor 42 for driving the low pressure compressor 42 by the low pressure turbine 44.

[0036] The low pressure compressor 42 is arranged upstream of the high pressure compressor 30 and supplies the latter with compressed air. The low pressure turbine 44 is arranged downstream of the high pressure turbine 32 and receives the exhaust gases leaving the latter.

[0037] The low pressure shaft 46 is guided in rotation relative to the nacelle 20 by means of bearings (not shown).

[0038] The low pressure shaft 46 is coaxial with the high pressure shaft 34. It therefore also has the longitudinal axis X as its axis of rotation. In particular, the low pressure shaft 46 extends inside the high pressure shaft 34.

[0039] The turbomachine 12 also comprises a fan 50 for driving the air flow in an external circulation vein 52 surrounding the nacelle 20. A primary air flow A (hot) is thus distinguished, consisting of the portion of the air flow driven in the internal circulation vein 22, and a secondary air flow B (cold), consisting of the portion of the air flow driven in the external circulation vein 52.

[0040] The fan 50 comprises a fan rotor 54. This fan rotor 54 is rotatably mounted relative to the nacelle 20 about the longitudinal axis X. It comprises a hub 55 (Figure 3) provided with fan blades 56 extending substantially radially outward from the hub 55. These blades 56, when rotated, drive the air flow in the external circulation vein 52.

[0041] As seen in Figure 4, each blade 56 includes a leading edge 57A, a trailing edge 57B and a chord C connecting the leading edge 57A to the trailing edge 57B.

[0042] Returning to Figure 2, the fan rotor 54 is driven in rotation by the low pressure turbine 44, via the low pressure shaft 46. This drive is typically done via a reduction gear allowing the fan rotor 54 to rotate at a speed lower than that of the low pressure shaft 46. Alternatively, this drive is direct, that is to say that the fan rotor 54 is integral in rotation with the low pressure shaft 46.

[0043] In the example shown, the fan 50 also comprises a fan stator 58 comprising fixed blades 59 arranged at the periphery of the nacelle 20, in the external circulation vein 52, along a plane orthogonal to the longitudinal axis X. This fan stator 58 is here arranged downstream of the fan rotor 54. As a variant (not shown), the fan 50 comprises, instead of the fan stator 58, a counter-rotating fan rotor.

[0044] Advantageously, the fan 50 is, as shown, unducted, that is to say that the external circulation vein 52 has no peripheral delimitation. The turbomachine 12 is then constituted, as shown, by a turbojet engine with an unducted fan or, alternatively, by a turboprop. As a variant (not shown), the external circulation vein 52 is defined between the nacelle 20 and a fan casing surrounding the fan 50; the turbomachine 12 is then typically constituted by a turbojet engine with a high bypass ratio, the bypass ratio being defined as the ratio of the flow rate of the secondary flow B (cold) to the flow rate of the primary flow A (hot).

[0045] In the example shown, the turbomachine 12 is in particular of the “puller” type, that is to say that the fan 50 is arranged upstream of the internal circulation vein 22 and also drives the air flow in the latter. In a variant (not shown), the turbomachine is of the “pusher” type, that is to say that the fan 50 is placed around the downstream half of the nacelle 20.

[0046] The blades 56 of the fan rotor 54 are variable-pitch, that is to say that each blade 56 is pivotally mounted relative to the hub 55 around its own pivot axis P. This pivot axis P extends in the direction of elongation of the blade 56. It is orthogonal to the longitudinal axis X.

[0047] Each blade 56 is in particular able to pivot around the axis P relative to the hub 55 between a so-called flag position, in which the chord C of the blade 56 is substantially parallel to the longitudinal axis X, and a so-called sail position, in which the chord C of the blade 56 is substantially orthogonal to the longitudinal axis X. Preferably, each blade 56 is also able to pivot beyond the sail position, to a so-called reverse position, in which the chord C of the blade 56 forms an angle strictly greater than 90°, for example substantially equal to 95°, with the longitudinal axis X. The blades 56 being most often twisted, the chord C taken as a reference for measuring the pitch angle is, by convention, constituted by the chord of the blade at 75% of the radius of the fan rotor 54.

[0048] For this purpose, each blade 56 is secured, as visible in Figure 3, to an attachment part 60 arranged at the blade root. This attachment part 60 is rotatably mounted relative to the hub 55 around the pivot axis P. More precisely, the attachment part 60 is rotatably mounted inside a housing 62 formed in the hub 55 by means of balls 64 or other rolling elements.

[0049] The fan 50 further comprises a pitch change mechanism 70 for adjusting the pitch angle of each blade 56 around its pivot axis P so as to adapt the performance of the turbomachine 12 to the different phases of flight.

[0050] With reference to Figure 3, this pitch change mechanism 70 comprises a frame 72, a control cylinder 74, a system 76 for controlling the cylinder 74 and a connecting system. The frame 72 is secured to the hub 55 and is typically constituted by a part of the hub 55. It is thus fixed relative to the pivot axes P.

[0051] The frame 72 comprises a base 80. This base 80 is centered on the longitudinal axis X. Here, it is crossed by the pivot axes P.

[0052] In the example shown, the base 80 delimits a housing 82 open downstream. This housing 82 is in particular cylindrical, typically cylindrical of revolution, and centered on the X axis. An oil transfer bearing 84 is received in said housing 82.

[0053] In the example shown, the frame 72 also comprises a cylinder 86 projecting upstream from the base 80. This cylinder 86 is centered on the X axis and open at its upstream end 88. It is typically cylindrical of revolution.

[0054] The base 80 and the peripheral cylinder 86 together delimit an external peripheral surface 88 of the frame 72. This external peripheral surface 88 is substantially cylindrical and centered on the axis X. It is oriented radially outwards.

[0055] The control cylinder 74 comprises a fixed part 100, integral with the frame 72, and a movable part 102 movable in translation along the longitudinal axis X relative to the fixed part 100 between a retracted position, shown in Figure 3, and a deployed position (not shown). Optionally, the movable part 102 is also movable in rotation around the longitudinal axis X over a restricted angle, for example of the order of 5°.

[0056] The control cylinder 74 comprises in particular a continuous cylinder 104, forming one of the fixed part 100 and the mobile part 102 and a piston 106 forming the other of the fixed part 100 and the mobile part 102. Here, the cylinder 104 forms the mobile part 102 and the piston 106 forms the fixed part 100. In a variant (not shown), it is the opposite: the cylinder 104 forms the fixed part 100 and the piston 106 forms the mobile part 102.

[0057] Thus, in the example shown, the cylinder 104 extends around the external peripheral surface 88 of the frame 72, coaxially with the latter, and the piston 106 is constituted by a collar 108 secured to the frame 72 extending radially outwards from the external peripheral surface 88 to the cylinder 104.

[0058] The cylinder 104 defines an internal cavity 110. The piston 106 divides said internal cavity 110 into two contiguous fluid chambers 112, 114. Each contains a control fluid, typically constituted by an oil, for controlling the movement of the movable part 102 relative to the fixed part 100. This control fluid is at a first pressure in the first fluid chamber 112 and at a second pressure in the second fluid chamber 114. The first and second fluid chambers 112, 114 are arranged such that the relative increase in the first pressure (i.e., relative to the second pressure) causes the piston 110 to move towards its extended position, the relative increase in the second pressure (i.e., relative to the first pressure) causes the piston 110 to move towards its retracted position.

[0059] Here, each of the fluid chambers 112, 114 is delimited internally by the external peripheral surface 88 of the frame 72 and externally by the cylinder 104. The first fluid chamber 112 is furthermore delimited at its downstream end by the piston 106 and the second fluid chamber 114 is delimited at its upstream end by the piston 106.

[0060] The 74 control cylinder is thus particularly compact, which makes it lighter.

[0061] In the example shown in Figure 3, the movable part 102 also comprises an upstream guide ring 116 and a downstream guide ring 118 each integral with the cylinder 104 and extending radially inward from the cylinder 104 to the external peripheral face 88 of the frame 72. The upstream guide ring 116 is arranged upstream of the piston 106 and delimits an upstream end of the first fluid chamber 112. The downstream guide ring 118 is arranged downstream of the piston 106 and delimits a downstream end of the second fluid chamber 114.

[0062] In the example shown in Figure 3, each of the upstream and downstream guide rings 116, 118 constitutes a sealing ring and longitudinally closes the first fluid chamber 112, respectively the second fluid chamber 114. The fluid chambers 112, 114 are thus closed at each of the longitudinal ends of the control cylinder 74.

[0063] Alternatively (not shown), only the downstream guide ring 118 constitutes a sealing ring. The upstream guide ring 116 has holes allowing the control fluid to flow through the upstream guide ring 116.

[0064] As a further variant (not shown), the moving part 102 does not include an upstream guide ring 116.

[0065] The control system 76 includes a pressure generator 130 for raising the control fluid to a third pressure higher than the first and second pressures, a pressure control unit 132 for adjusting the pressure of the control fluid in the first and second fluid chambers 112, 114 using the third pressure, and a return line 136 for discharging the depressurized control fluid. The control system 76 also includes a main reservoir 133, a backup circuit 134, and a control module 135.

[0066] The pressure generator 130 comprises, for example, a pump capable of pumping the fluid to bring it to the third pressure, for example 100 bars. A main pressure relief valve 139A makes it possible to evacuate a portion of the control fluid to the return line 136 when the pressure of the control fluid downstream of the pressure generator 130 exceeds the third pressure.

[0067] The pressure control unit 132 is supplied with control fluid at the third pressure by the pressure generator 130. It is fluidically connected to the first fluid chamber 112 and to the second fluid chamber 114 via the oil transfer bearing 84. It is able to distribute the control fluid between the first fluid chamber 112 and the second fluid chamber 114 so as to adjust the fluid pressure inside each of these chambers 112, 114 and, thus, adjust the position of the piston 110 between its retracted and extended positions. It is also able to discharge control fluid from the first and second fluid chambers 112, 114 into the return line 136.

[0068] The main reservoir 133 is configured to collect depressurized control fluid from the return line 136. It supplies the pressure generator 130.

[0069] The emergency circuit 134 is capable of supplying the first fluid chamber 112 with control fluid so as to move the piston 110 to its deployed position in the event of failure of the pressure generator 130. For this purpose, the emergency circuit 134 comprises an auxiliary reservoir 137 and an auxiliary pump 138. In the example shown, it also comprises an auxiliary pressure relief valve 139B.

[0070] The auxiliary tank 137 is configured to collect depressurized control fluid from the return line 136. It supplies the auxiliary pump 138. In the example shown, it also supplies the main tank 133, with the depressurized control fluid from the return line 136 passing through the auxiliary tank 137 before reaching the main tank 133.

[0071] The auxiliary pump 138 is capable of pumping the control fluid into the auxiliary reservoir 137 to bring it to the third pressure. It is fluidically connected to the pressure control unit 132 so as to supply it with control fluid at the third pressure, the pressure control unit 132 being configured to redirect all of the control fluid coming from the auxiliary pump 138 to the first fluid chamber 112.

[0072] The pressure relief valve 139B is adapted to discharge a portion of the control fluid to the return line 136 when the pressure of the control fluid downstream of the auxiliary pump 138 exceeds the third pressure.

[0073] The control module 135 is configured to receive a timing instruction (not shown) and deduce therefrom a control signal transmitted to the pressure control unit 132. In particular, the control module 135 is configured to transmit to the pressure control unit 132 a control signal intended to increase the fluid pressure in the first chamber 112 when the timing instruction aims to increase the pitch of the blades 56, and to transmit to the pressure control unit 132 a control signal intended to increase the fluid pressure in the second chamber 114 when the timing instruction aims to reduce the pitch of the blades 56.

[0074] The control module 135 is also configured to transmit to the emergency circuit 134, more particularly to its auxiliary pump 138, a start instruction in the event of failure of the pressure generator 130.

[0075] The connecting system 78 connects the mobile part 102 to each blade 56 so as to convert the translation of the mobile part 102 along the longitudinal axis X and, where appropriate, the rotation of the mobile part 102 around the longitudinal axis X into a rotation of each blade 56 around its pivot axis P. In particular, the connecting system 78 connects the mobile part 102 to each blade 56 so as to convert:

[0076] - the translation of the mobile part 102 along the longitudinal axis X in a first direction in a rotation of the variable-pitch blade 56 around the pivot axis P towards the sail position, and

[0077] - the translation of the movable part 102 along the longitudinal axis X in a second direction opposite to the first direction in a rotation of the variable-pitch blade 56 around the pivot axis P towards the flag position.

[0078] For this purpose, the connection system 78 comprises a synchronization ring 140 secured to the moving part 102 and, for each of the blades 56, a mechanism 142 for connecting the blade 56 to the synchronization ring 140.

[0079] The synchronization ring 140 extends in a radial plane around the moving part 102. It is in particular fixed to an upstream end 143 of the moving part 102.

[0080] Each connecting mechanism 142 comprises a first articulation 144 secured to the movable part 102, a second articulation 146 secured to the blade 56, away from the pivot axis P of said blade 56, and a connecting member 148 connecting the first articulation 144 to the second articulation 146.

[0081] The first articulation 144 is carried by the synchronization crown 140. Here it is constituted by a ball joint.

[0082] The second articulation 146 is also constituted by a ball joint. It is eccentric relative to the pivot axis P.

[0083] The connecting member 148 has a first end 150 articulated to the first articulation 144 and a second end 152 articulated to the second articulation 146. Advantageously, the connecting member 148 is rigid and of adjustable length, that is to say that the distance between the first and second ends 150, 152 can be modified, which makes it possible to precisely adjust the length when stationary so as to allow the control of the setting angle of each blade 56 by the pitch change mechanism 70.

[0084] The connecting member 148 is here constituted by a connecting rod 153.

[0085] In the example shown, each connecting mechanism 142 also comprises a crank 154 connecting the attachment part 60 to the second articulation 146. This crank 154 is rigid and integral with the attachment part 60. It extends at least partly in a direction orthogonal to the pivot axis P. It forms an arm for rotating the blade 56.

[0086] In the example shown, the first direction is from upstream to downstream, that is to say that the movement of the movable member 102 towards its retracted position causes a rotation of each blade 56 towards its sail position, and the second direction is from downstream to upstream, that is to say that the movement of the movable member 102 towards its deployed position causes a rotation of each blade 56 towards its flag position. In addition, the first articulation 144 is arranged upstream of the second articulation 146.

[0087] For this purpose, the second articulation 16 is, as visible in Figure 4, placed opposite the trailing edge 57B relative to a plane Q orthogonal to the chord C and containing the pivot axis P.

[0088] Alternatively (not shown), the first direction goes from downstream to upstream, the first articulation 144 being arranged downstream of the second articulation 146. The second articulation 146 is then placed on the same side of the trailing edge 57B relative to the plane Q orthogonal to the chord C and containing the pivot axis P.

[0089] These particular arrangements allow, when the pitch change mechanism 70 is immobilized, that the natural stresses of the blade 56 towards its sail position cause the connecting member 148 to work in tension and not in compression. The risk of buckling of the connecting member 148 is therefore very low, so that it is possible to use a relatively weak connecting member 148 and thus to lighten the pitch change mechanism 70.

[0090] The pitch change mechanism 70 also comprises a pitch locking device 160 capable of blocking the translation of the movable part 102 of the control cylinder 74 in the first direction, that is to say here towards its retracted position.

[0091] This locking device 160 comprises a cylindrical surface 162 movable together with the movable part 102 relative to the fixed part 100 and a blocking member 164 for immobilizing the movable part 102 relative to the fixed part 100 by engaging with the cylindrical surface 162.

[0092] The cylindrical surface 162 is in particular integral with the movable part 102. The cylindrical surface 162 is advantageously, as shown, substantially coaxial with the axis X.

[0093] In the example shown, the cylindrical surface 162 is carried by an internal cylinder 165 housed inside the cylinder 86.

[0094] This internal cylinder 165 is here connected to the mobile part 102 by a ferrule 166. This ferrule 166 here projects longitudinally upstream from the control cylinder 74. It is in particular frustoconical, its diameter decreasing from its downstream end 167, attached to the cylinder 74, to its upstream end 168, attached to an upstream end 169 of the internal cylinder 165.

[0095] In the example shown, the cylindrical surface 162 constitutes an external face of the internal cylinder 165. In a variant (not shown), the cylindrical surface 162 constitutes an internal face of the internal cylinder 165. In a further variant (not shown), the cylindrical surface 162 is carried directly by the movable part 102; it typically constitutes an internal or external surface of the cylinder 104.

[0096] Referring to Figures 5-8, the cylindrical surface 162 is notched with a plurality of notches 170 each extending orthogonally to the longitudinal axis X.

[0097] Advantageously, the notches 170 are formed on only the portion of the cylindrical surface 162 which faces the locking member 164 when the blades 56 are oriented according to the large pitches, that is to say when the pitch angle of the blades 56 is less than 60°. In other words, the portion of the cylindrical surface 162 which faces the locking member 164 when the blades 56 are oriented according to the small pitches or in reverse is devoid of notch 170.

[0098] The cylindrical surface 162 comprises, for each pair of consecutive notches 170, a rib 172 separating said notches 170. Said rib 172 has inclined flanks 174. These flanks 174 have a maximum inclination, measured relative to the axis X, preferably less than 88°, in particular less than 60°.

[0099] Returning to Figure 3, the locking member 164 comprises at least one ring 180 arranged orthogonally to the longitudinal axis X. Said ring 180 is preferably, as shown, substantially coaxial with the axis X.

[0100] With reference to Figures 9 and 10, the ring 180 is circumferentially divided into several sectors 182 movable relative to each other between a close configuration, shown in Figure 10, in which the ring 180 has a reduced diameter, and a spaced configuration, shown in Figure 9, in which the ring 180 has an increased diameter. These sectors 182 are at least two in number. Preferably, their number is greater than or equal to four. In the example shown, the sectors 182 are four in number.The locking member 164 thus has an unlocking configuration, shown in Figure 5, in which the diameter of the ring 180 is such that the locking member 164 is away from the cylindrical surface 162, and a locking configuration, shown in Figure 6, in which the diameter of the ring 180 is such that the locking member 164 is engaged with the cylindrical surface 162 while being engaged in at least one of the notches 170.

[0101] In the example shown, the locking member 164 extends, as visible in Figure 3, around the cylindrical surface 162. The cylindrical surface 162 is therefore interposed between the longitudinal axis X and the locking member 164. The locking member 164 is thus in the locking configuration when the sectors 182 of the ring 180 are in the retracted configuration, and in the unlocking configuration when said sectors 182 are in the spaced apart configuration. This arrangement is advantageous because it allows the centrifugal force to which the locking member 164 is subjected when the fan rotor 54 is rotating to maintain the locking member in its unlocking configuration.

[0102] Alternatively (not shown), the cylindrical surface 162 extends around the locking member 164. The locking member 164 is then in the locking configuration when the sectors 182 of the ring 180 are in the spaced configuration, and in the unlocking configuration when said sectors 182 are in the retracted configuration. This is for example the case when the cylindrical surface 162 constitutes an internal face of the internal cylinder 165 or of the cylinder 104.

[0103] Each 182 sector is rigid. It is typically made of metal.

[0104] Returning to Figures 9 and 10, the ring 180 further advantageously comprises a return element 184 urging the sectors 182 towards that of the spaced apart and close together configurations in which the locking member 164 is in the unlocking configuration. This return element 184 is here formed by an elastic ring, for example an O-ring, delimiting the interior of the ring 180 and to the outside of which the sectors 182 are attached. Thus, the unlocking configuration constitutes the configuration of the locking member 164 when it is at rest.

[0105] Returning to Figures 5 and 6, the ring 180 comprises a first circumferential face 190 oriented radially towards the cylindrical surface 162, a second circumferential face 192 opposite the first face 190 (and therefore oriented radially opposite the cylindrical surface 162), a first annular face 194 delimiting the ring 180 longitudinally upstream and a second annular face 196 delimiting the ring 180 longitudinally downstream. In the example shown, the locking member 164 surrounding the cylindrical surface 162, the first circumferential face 190 constitutes an internal face of the ring 180 and the second circumferential face 192 constitutes an external face of the ring 180. Alternatively, when the locking member 164 is surrounded by the cylindrical surface 162, it is the reverse.

[0106] The ring 180 preferably has, as shown, a longitudinal extension (i.e. between its annular faces 194, 196) less than or equal to the longitudinal extension of each notch 170. Thus, when the blocking member 164 is in the locking configuration, the ring 180 is engaged in only one of the notches 170, which facilitates the design and dimensioning of the locking device 160.

[0107] The locking member 164 is adapted to immobilize the movable part 102 in translation relative to the fixed part 100 when it is in the locking configuration. For this purpose, it is substantially fixed in the longitudinal direction relative to the fixed part 100. It is typically, as shown, at least partially engaged in at least one circumferential groove 198 formed in a wall 199 of the frame 72. In particular, the or each ring 180 forming the locking member 164 is at least partially engaged in a respective circumferential groove 198 formed in said wall 199.

[0108] The wall 199 is, in the example shown, constituted by the cylinder 86, the rib 198 being formed in an internal face of the latter.According to other variants (not shown): the wall 199 is formed by a cylinder coaxial with the axis X and surrounded by the internal cylinder 165, the rib 198 being formed in an external face of this cylinder; this is typically the case when the cylindrical surface 162 constitutes an internal face of the internal cylinder 165; the wall 199 delimits at least in part the external peripheral surface 88 of the frame 72, the rib 198 being formed in said external peripheral surface 88; this is typically the case when the cylindrical surface 162 constitutes an internal surface of the cylinder 104; the wall 199 is formed by an external cylinder which surrounds the control cylinder 74, the rib 198 being formed in an internal face of this external cylinder; this is typically the case when the cylindrical surface 162 constitutes an external surface of the cylinder 104.

[0109] Still with reference to Figures 5 and 6, the locking device 160 also comprises a movable member 200, movable in translation relative to the frame 72 and to the blocking member 164 between a retracted position, shown in Figure 5, in which it leaves the blocking member 164 free to be in its unlocking configuration and a deployed position, shown in Figure 6, in which it forces the blocking member 164 into its locking configuration. For this purpose, the movable member 200 is housed in a space 202 into which the rib 198 opens opposite the cylindrical surface 162. It is free to move in translation in the longitudinal direction (i.e. parallel to the longitudinal axis X) inside this space 202. In the example shown, said space 202 is formed by a cavity inside the wall 199.

[0110] The movable member 200 has a retaining face 204 capable of being in contact with the second face 192 of the ring 180 when the locking member 164 is in the locking configuration. For this purpose, this retaining face 204 has a longitudinal extension and delimits in a radial plane a closed contour which has a diameter substantially equal to the diameter of the second face 192 of the ring 180 in the retracted configuration. Advantageously, it is, as shown, devoid of radial extension. In the retracted position, the retaining face 204 is longitudinally spaced from said second face 192. In the deployed position, the retaining face 204 and the second face 192 are crossed by the same radial plane; the retaining face 204 thus prevents the locking member 164 from returning to its unlocking configuration.

[0111] The movable member 200 also has a contact face 206 through which it comes into contact with the ring 180, in particular with a contact edge 207 of the second face 192 of the ring 180, when it moves from its retracted position to its deployed position. This contact face 206 is located between the ring 180 and the retaining face 204 when the movable member 200 is in the retracted position. It has a radial extension.

[0112] The contact face 206 extends radially from an end edge 208 delimiting a longitudinal end of the retaining face 204. Said end edge 208 thus forms a junction between the contact face 206 and the retaining face 204.

[0113] In the example shown, said contact face 206 is beveled, that is to say it has a longitudinal extension, opposite the retaining face 204, in addition to its radial extension. The force that must be exerted by the movable member 200 on the locking member 164 to force it into its locking configuration is thus reduced.

[0114] In the example shown, the contact face 206 is also provided with a plurality of bearings 210. These bearings 210 are preferably, as shown, distributed circumferentially along the end edge 208. These bearings 210 contribute to reducing the friction between the movable member 200 and the locking member 164 and therefore to further reducing the force that must be exerted by the movable member 200 on the locking member 164 to force it into its locking configuration.

[0115] Alternatively (not shown), the contact face 206 is not provided with any bearing 210, or it is not beveled. In the example shown, the movable member 200 comprises a ring 212 carrying the retaining face 204 and the contact face 206. The retaining face 204 is thus cylindrical and the contact face 206 is annular, in particular frustoconical. Alternatively (not shown), the retaining face 204 and the contact face 206 are carried by arms projecting longitudinally from a synchronizing ring; the retaining face 204 and the contact face 206 are then each formed of several sections spaced circumferentially from one another.

[0116] Still with reference to Figures 5 and 6, the locking device 160 further comprises a return member 220 urging the movable member 200 towards its deployed position, and a holding device 222 for holding the movable member 200 in its retracted position under certain predetermined conditions, typically when the third pressure is greater than a threshold, said threshold being less than a minimum supply pressure of the fluid chambers 112, 114 under normal operating conditions. Such a minimum supply pressure of the fluid chambers 112, 114 under normal operating conditions is the minimum pressure supplied by the pressure generator 130 in the absence of any malfunction, in particular in the absence of a leak or breakdown.

[0117] Thanks to the return member 220, the position of the mobile member 200 at rest is the deployed position. This makes it possible to force the locking member 164 into its locking configuration even in the event of a breakdown.

[0118] The return member 220 is here constituted by a compression spring compressed between the frame 72 and a shoulder 224 secured to the movable member 200.

[0119] The holding device 222 comprises a counterbalance cylinder 230 having a counterbalance piston 232 and a counterbalance chamber 234.

[0120] The counterbalancing piston 232 is mounted to move in translation along the longitudinal axis X relative to the frame 72. It is in particular coaxial with the moving member 200. In the example shown, it is arranged in the longitudinal extension of the moving member 200, between the moving member 200 and the return member 220. It delimits in particular the shoulder 224 against which the return member 220 bears.

[0121] The counterbalancing chamber 234 is delimited between the counterbalancing piston 232 and the frame 72. In particular, the counterbalancing chamber 234 is delimited between the counterbalancing piston 232 and a wall 236 separating said chamber 234 from the space 200.

[0122] The counterbalancing chamber 234 is fluidically connected to the pressure generator 130 by a fluid connection circuit 238 (Figure 3) so as to be supplied with control fluid at the third pressure. It is intended to counterbalance the stress of the return device 220 when this supply is active. For this purpose, the counterbalancing cylinder 230 is arranged so that the pressure exerted on the piston 232 by the fluid contained in the chamber 234 is oriented in a direction opposite to that of the stress of the return device 230. In the example shown, the counterbalancing piston 232 is interposed between the chamber 234 and the shoulder 224 and the shoulder 224 is interposed between the piston 232 and the return device 220.In addition, the counterbalance piston 232 and the counterbalance chamber 234 are sized so that, when the chamber 234 is supplied with control fluid at a pressure above the threshold, the force exerted by the control fluid on the piston 232 is greater than the stress on the return device 220.

[0123] Thus, as long as the pressure supplied to the chamber 234 is greater than the threshold, the stress on the return device 220 is canceled and the movable member 200 is maintained in the retracted position. On the other hand, when the chamber 234 is no longer supplied with control fluid at a pressure greater than the threshold, typically when the pressure generator 130 fails, the force of the return device 220 prevails and the movable member 200 is moved into its deployed position.

[0124] With reference to Figure 3, the pressure control unit 132 is here fluidly interposed between the pressure generator 130 and the fluid connection circuit 238. It has a first configuration, in which it isolates the fluid connection circuit 238 from the return line 136, and a second configuration, in which it fluidly connects the fluid connection circuit 238 to the return line 136.

[0125] The pressure control unit 132 is configured to normally be in its first configuration and to switch to its second configuration upon receipt of a control instruction transmitted by the control module 135.

[0126] Returning to Figures 5 and 6, the locking device 160 finally comprises an elastic sheath 240 between the cylindrical surface 162 and the fixed part 100, in particular between the cylindrical surface 162 and the wall 199. This elastic sheath 240 here comprises an upstream portion 242 connecting an upstream edge 244 of the wall 199 to an upstream edge 246 of the surface 162 and a downstream portion 248 connecting a downstream edge 250 of the wall 199 to a downstream edge 252 of the surface 162. As a variant (not shown), the elastic sheath 240 comprises only the upstream portion 242 or only the downstream portion 248.

[0127] The elastic sheath 240 is dust- and liquid-tight. It isolates the cylindrical surface 162 from the environment. It is capable of elastically deforming when the movable part 102 moves relative to the fixed part 100 while maintaining its sealing. Thus, the cylindrical surface 162 is protected from fouling that could fill the notches 170. Maintenance of the locking device 160 is therefore reduced. As a variant (not shown), the locking device 160 does not include the elastic sheath 240. This is particularly the case when the surface 162 is in a space in fluid communication with one of the chambers 112, 114, for example when the upstream guide ring 116 has holes allowing the control fluid to flow through the upstream guide ring 116 or when the movable part 102 does not include an upstream guide ring 116.

[0128] In the variant of Figures 5 and 6, the flanks 174 of the ribs 172 of the cylindrical surface 162 are straight. The inclination of the flanks 174 is then preferably at least equal to 45°.

[0129] Furthermore, still in this variant, the sectors 182 of the ring 180 each have a polygonal section. Each sector 182 then comprises two flanks 260 delimiting the sector 182 in the longitudinal direction. In the example shown, these flanks 260 converge towards each other in the direction of the cylindrical surface 162. Advantageously, they are substantially symmetrical with respect to a plane orthogonal to the longitudinal axis X and form between them an angle of between 4° and 90°, in particular greater than 60°.

[0130] Thanks to this inclination of the flanks 174 and the convergence of the flanks 260, the shear forces supported by the ribs 172 and the locking member 164 are limited, which makes it possible to increase the service life of the locking device 160. Nevertheless, these inclinations and convergences remain sufficiently low to limit the radial forces transmitted to the mobile member 200; thus, it is possible to maintain a relatively modest return force for the return member 220, which makes it possible to limit the size of the counterbalancing chamber 234 and therefore the size of the mechanism 70.

[0131] Furthermore, still in this variant of Figures 5 and 6, the contact edge 207 is beveled. This makes it possible to further limit the force that must be exerted by the movable member 200 on the locking member 164 to force it into its locking configuration. Here again, this contributes to limiting the restoring force of the member 220 and thus also the size of the counterbalancing chamber 234 and therefore the size of the mechanism 70.

[0132] In the variants of Figures 7 and 8, the ribs 172 of the cylindrical surface 162 each have a rounded top. In addition, the notches 170 of said surface 162 each have a rounded bottom, the transition from each rib top 172 to each notch bottom 170, via a rib flank 174 172, being made without a break in slope. The cylindrical surface 162 then has an undulating profile, as visible in the Figures. In this case, the inclination of the flanks 174 of the ribs 172 varies from each notch bottom 170 to each rib top 172 and reaches a maximum at an inflection point substantially halfway between the notch bottom 170 and the rib top 172; this maximum inclination is advantageously less than 45°.

[0133] Furthermore, still in these variants of Figures 7 and 8, each sector 182 of the or each ring 180 has a circular or ovoid section.

[0134] This makes it possible to reduce the friction of the locking member 164 on the cylindrical surface 162 under normal operating conditions, i.e. when the locking member 164 is in the unlocking configuration. This is particularly advantageous when the or each ring 180 is devoid of a return element 184.

[0135] Finally, in the variant of Figure 8, the locking member 164 comprises several rings 180, in this case two. This makes it possible to reduce the shear forces supported by the ribs 172 and each ring 180. The service life of the locking device 160 is thus increased.

[0136] The movable member 200 then comprises a retaining surface 204 and a contact surface 206 for each ring 180.

[0137] A method of changing the pitch of the blades 56, implemented by the pitch changing mechanism 70, will now be described.

[0138] In a first step of this method, the control module 135 first receives a setting instruction aimed at increasing the pitch of the blades 56. The control module 135 then transmits to the pressure control unit 132 a control signal intended to increase the fluid pressure in the first chamber 112. As the fluid pressure in the first chamber 112 increases, the movable part 102 of the cylinder 74 moves in the second direction, towards its deployed position, which, via the connecting system 78, causes the blades 56 to pivot towards the large pitches (i.e. towards the flag position).

[0139] Under the effect of centrifugal force, possibly coupled with the stress of the return element 184, the locking member 164 remains in the unlocking configuration away from the cylindrical surface 162 and therefore does not oppose the movement of the movable part 102.

[0140] Once the moving part 102 has reached an equilibrium position, it stabilizes, the blades 56 maintaining a fixed orientation.

[0141] In a second step of the pitch change method, the control module 135 first receives a setting instruction to reduce the pitch of the blades 56. The control module 135 then transmits to the pressure control unit 132 a control signal to increase the fluid pressure in the second chamber 114. As the fluid pressure in the second chamber 114 increases, the movable part 102 of the cylinder 74 moves in the first direction towards its retracted position, which, via the connection system 78, causes the blades 56 to pivot towards the small pitches (i.e. towards the sail position).

[0142] Under the effect of centrifugal force, possibly coupled with the stress of the return element 184, the locking member 164 remains in the unlocking configuration away from the cylindrical surface 162 and therefore does not oppose the movement of the movable part 102.

[0143] Once the moving part 102 has reached an equilibrium position, it stabilizes, the blades 56 maintaining a fixed orientation.

[0144] Optionally, the pitch change method also comprises, following the first or second step, a step of controlled locking of the orientation of the blades 56.

[0145] During this step, the control module 135 transmits a pitch locking command to the pressure control unit 132. Under the effect of this command, the pressure control unit 132 fluidly connects the fluid connection circuit 256 to the return line 136, causing a drop in the fluid pressure in the counterbalancing chamber 234. The fluid pressure in said chamber 234 then falls below the threshold and is therefore insufficient to counterbalance the stress of the return device 220, which thus causes the deployment of the movable member 200. The latter then presses on the second face 192 of the or each ring 180, which forces the locking member 164 to tilt into its locking configuration.

[0146] If the or each ring 180 is opposite a notch 170 when this deployment occurs, the or each ring 180 engages in a respective notch 170 and the tilting of the locking member 164 into its locking configuration is complete. The blades 56 are thus locked in their orientation even in the event of loss of fluid pressure in one of the chambers 112, 114.

[0147] If, on the contrary, at least one ring 180 is opposite a rib 172 when this deployment occurs, this rib 172 prevents the locking member 164 from fully engaging with the cylindrical surface 162 and the tilting of the locking member 164 into its locking configuration is complete. The blades 56 are then not blocked in their orientation in the event of a loss of fluid pressure in one of the chambers 112, 114. Nevertheless, if such a loss of fluid pressure occurs, it will cause the displacement of the cylindrical surface 162 until a notch 170 is opposite the or each ring 180; the tilting of the blocking member 164 in its locking configuration then no longer being held back by the presence of a rib 172, it will end, immobilizing the blades 56. Thus, the pivoting of the blades 56 in the event of loss of fluid pressure remains limited.In the event of a malfunction of the control system 76, typically in the event of a failure of the pressure generator 130, the pitch change method comprises an additional step of non-controlled locking of the orientation of the blades 56.

[0148] During this step, the malfunction of the control system 76 causes a drop in the fluid pressure in the counterbalancing chamber 234, typically because the pressure generator 130 is no longer able to raise the third pressure above the threshold. The fluid pressure in said chamber 234 is then insufficient to counterbalance the stress of the return device 220, which thus causes the deployment of the mobile member 200. The latter then presses on the second face 192 of the or each ring 180, which forces the locking member 164 to tilt into its locking configuration.

[0149] It will be noted that, in this case, the or each ring 180 is almost systematically opposite a notch 170 when this deployment occurs. Indeed, the loss of pressure in the chamber 234 is then almost always accompanied by a loss of pressure in at least one of the chambers 112, 114 and therefore by the displacement of the cylindrical surface 162 relative to the locking member 164. The or each ring 180 therefore engages in a respective notch 170 and the tilting of the locking member 164 into its locking configuration is complete. The blades 56 are thus locked in their orientation. In particular, the pivoting of the blades 56 towards the small pitches is then prevented by the locking device 160.

[0150] The non-controlled locking step is followed by a step of securing the fan 50. During this step, the emergency circuit 134 is activated and supplies the first fluid chamber 112 and the counterbalancing chamber 234 with control fluid so as to increase the fluid pressure in these chambers. Under the effect of the increase in pressure in the chamber 234, the movable member 200 retracts and the blocking member 164 returns to the unlocking configuration. The movable part 102 is therefore no longer immobilized and can move downstream under the effect of the increase in pressure in the first fluid chamber 112 until the blades 56 are in the flag position.

[0151] It should be noted that these different stages can be implemented independently of each other.

[0152] Thus, thanks to the embodiments described above, it is possible, in a simple and robust manner, to lock the current orientation of the blades 56 (with a certain tolerance). This locking is made possible even in the absence of power supply to the cylinder 74 and even with a low force, but nevertheless withstands very high loads. And this locking is permitted without significantly increasing the size of the mechanism 70.

[0153] It will be noted that, although the above description has been given for the embodiment in which the cylindrical surface 162 is movable jointly with the movable part 102 relative to the fixed part 100, the invention is in no way limited to this single embodiment. Thus, in another embodiment (not shown), it is the locking member 164 which is movable jointly with the movable part 102 relative to the fixed part 100, the cylindrical surface 162 then being integral with the fixed part 100.

Claims

CLAIMS 1. Fan rotor (54) for a turbomachine comprising a hub (55) and a plurality of variable-pitch blades (56) each pivotable relative to the hub (55) about a specific pivot axis (P), the rotor (54) further comprising an actuator (70) for adjusting an angular position of each of the variable-pitch blades (56) about its respective pivot axis (P), the fixed part (100) being fixed relative to the pivot axis (P), the actuator (70) further comprising a connecting system (78) connecting the movable part (102) to the variable-pitch blade (56) so as to convert the translation of the movable part (102) along the longitudinal axis (X) into a rotation of the variable-pitch blade (56) about the pivot axis (P), the actuator comprising: a control cylinder (74) comprising a fixed part (100) and a movable part (102) movable in translation along a longitudinal axis (X) relative to the fixed part (100),the fixed part (100) and the movable part (102) delimiting between them two fluid chambers (112, 114) arranged so that the increase of a fluid pressure in one of the fluid chambers (112, 114) relative to a fluid pressure in the other fluid chamber (112, 114) causes the movement of the movable part (102) relative to the fixed part (100), and a locking device (160) capable of blocking the translation of the movable part (102) relative to the fixed part (100) in at least one direction, wherein the locking device (160) comprises: a surface (162) integral with the fixed part (100) or movable jointly with the movable part (102) relative to the fixed part (100), the surface (162) being notched with a plurality of notches (170) each extending orthogonally ... the longitudinal axis (X),a locking member (164) having an unlocking configuration away from the surface (162) and a locking configuration engaged with the surface (162) so that the movable part (102) is immobilized in translation relative to the fixed part (100), in which the locking member (164) is engaged in at least one of said notches (170), a movable member (200) movable in translation relative to the locking member (164) between a retracted position in which it leaves the locking member (164) free to be in its unlocking configuration and a deployed position in which it forces the locking member (164) into its locking configuration, a return member (220) urging the movable member (200) towards its deployed position, and a holding device (222) for holding the movable member (200) in its retracted position under certain predetermined conditions, the predetermined conditions consisting of a supply pressure of the fluid chambers (112, 114) greater than a threshold.

2. Fan rotor (54) according to claim 1, wherein the surface (162) comprises, for each pair of consecutive notches (170), a rib (172) separating said notches (170), said rib (172) having inclined flanks (174), said flanks (174) having a maximum inclination preferably less than 88°, in particular less than 60°, for example less than 45°.

3. The fan rotor (54) of claim 2, wherein the rib (172) has a rounded apex.

4. Fan rotor (54) according to claim 2 or 3, in which each notch (170) has a rounded bottom, the transition from a rib top (172) to a notch bottom (170), via a rib flank (174) of a rib (172), being made without a break in slope.

5. Fan rotor (54) according to any one of the preceding claims, wherein the locking member (164) comprises at least one ring (180) arranged orthogonally to the longitudinal axis (X), said ring (180) being circumferentially divided into several sectors (182) movable relative to each other between a close configuration, in which the ring (180) has a reduced diameter, and a spaced configuration, in which the ring (180) has an increased diameter, the locking member (164) being in the locking configuration when the ring (180) is in one of the spaced and close configurations and in the unlocking configuration when the ring (180) is in the other of the spaced and close configurations.

6. Fan rotor (54) according to claim 5, wherein the or each ring (180) is, in the locking configuration, engaged in only one of the notches (170) of the surface (162).

7. Fan rotor (54) according to claim 5 or 6, wherein each sector (182) has a circular or ovoid section.

8. Fan rotor (54) according to any one of the preceding claims, in which the locking member (164) has a first face (190) oriented towards the surface (162) and a second face (192) opposite the first face (190), and the movable member (200) comprises a retaining face (204) capable of being in contact with the second face (192) of the locking member (164) in the locking configuration.

9. Fan rotor (54) according to any one of the preceding claims, in which the movable member (200) has at least one contact face (206) by which it comes into contact with the locking member (164) when it moves from its retracted position to its deployed position, said contact face (206) being beveled and / or provided with at least one bearing (210).

10. A fan rotor (54) according to any preceding claim, wherein the surface (162) is cylindrical and the locking member (164) extends around said surface (162).

11. Fan rotor (54) according to any one of the preceding claims, wherein the surface (162) is movable together with the movable part (102), the locking member (164) being substantially fixed along the longitudinal axis (X) relative to the fixed part (100).

12. Fan rotor (54) according to any one of the preceding claims, wherein the threshold is less than a minimum supply pressure of the fluid chambers (112, 114) under normal operating conditions.

13. Turbomachine (12) comprising a fan rotor (54) according to any one of the preceding claims.

14. Aircraft (10) comprising at least one turbomachine (12) according to claim

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