Pitch changing mechanism having cylinder enclosing fluid delivery bearing

Abstract

A pitch change mechanism (70) includes a frame (72), an actuation cylinder (74) having a moving part (102) translatable relative to the frame (72), and a coupling system (78) connecting the moving part (102) to a variable pitch blade (56) to convert translation of the moving part (102) to rotation of the variable pitch blade (56). The pitch change mechanism also includes a fluid delivery bearing (257) for supplying actuation fluid from a source (76) to an actuation cylinder (74), the actuation cylinder (74) being rotatable relative to the source. An actuation cylinder (74) extends at least partially around the fluid delivery bearing (257).

Description

Technical Field

[0001] The invention relates to the general field of turbomachines equipped with at least one fan having variable-set blades, and more particularly to the control of the orientation of the fan airfoils of these turbomachines.

[0002] The preferred field of application of the invention is turbojet engines with unducted fans (more commonly known as propfan engines, open fan engines, open rotor engines and unducted fan engines). However, the invention is also applicable to turboprop engines with one or more propellers. Background Art

[0003] One of the avenues currently being explored to improve the specific power 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 fan rotors extending outside the nacelle of the engine, usually through reduction gears which enable the fan rotors to rotate at a lower speed than that of the turbine stage or stages.

[0004] As in the case of conventional turboprop engines, the blades of this or these rotors have a variable setting, i.e. the angular position of these blades, known as the setting angle, can be varied during flight. As a reminder, the setting angle of the blade is equivalent to the angle between the axis of rotation of the fan and the chord of the blade at 75% of the radius of the fan, in a plane orthogonal to the pivot axis of the blade. The setting angle of the blade can vary from a value equal to 90°, corresponding to the so-called "flat" position of the blade, to a value equal to 0°, corresponding to the so-called "feathered" position of the blade. The setting angle of the blade can also take values ​​strictly greater than 90° (generally approximately equal to 95°), corresponding to the so-called "reverse" position of the blade.

[0005] As is known, such modification of the setting angle during flight makes it possible to vary the thrust of the engine and optimize the efficiency of the fan according to the speed of the aircraft. Specifically, the rating of the fan is almost constant in all operating phases, and the blade setting causes the thrust to vary. Thus, in the cruising flight phase, the blades are oriented to regulate the thrust by minimizing the power consumption and the power taken from the turbine shaft and by optimizing the efficiency. Conversely, at takeoff, the blades are oriented to maximize the thrust for acceleration, thus taking off the aircraft.

[0006] Control of the orientation of the blades is usually accomplished by a pitch change mechanism comprising a control actuator comprising a part movable in translation along the axis of the fan and a coupling system coupling the movable part to the blades to convert the translation of the movable part into rotation of the variably set blades. The control actuator is usually a hydraulic cylinder supplied with fluid from a source fixed to the nacelle of the turbine, which requires providing a rotational transfer between a portion of the passage that is immovable in the nacelle reference frame and a portion of the passage that rotates with the fan rotor. This rotational transfer is usually accomplished by a rotary fluid transfer mechanism, usually called a "fluid transfer bearing".

[0007] Typically, the fluid transport bearing is arranged around the fan shaft upstream of the reduction gear. However, this arrangement does have a number of disadvantages:

[0008] - this arrangement is found to be particularly bulky as the fan shaft traverses the fluid transport bearing, and

[0009] - The turbine is elongated by inserting a fluid transfer bearing between the control actuator and the reduction gear,

[0010] The weight of the turbine is therefore increased, which increases the power consumption of the turbine.

[0011] In order to solve these problems, it has been proposed to arrange the fluid transfer bearing downstream of the reduction gear and to connect the fluid transfer bearing to the control actuator by a tube that crosses the reduction gear. This is the arrangement currently found on most turboprop engines. Although this arrangement is suitable for turbines whose fan shaft is offset relative to the turbine shaft (as for the vast majority of turboprop engines), this arrangement does present difficulties in the case of integration into a turbine whose fan shaft is coaxial with the turbine shaft (as is the case for unducted fan turbojets). Specifically, in this case, the following limitations arise:

[0012] - Difficult access to fluid conveying bearings, and

[0013] Since the fluid conveying bearing is traversed by the turbine shaft, the fluid conveying bearing proves to be particularly bulky.

[0014] Therefore, when it comes to equipping a turbomachine whose fan shaft is coaxial with the turbine shaft with a fluid-transporting bearing intended to supply the pitch-changing mechanism of the fan rotor, the existing solutions are unsatisfactory. Summary of the invention

[0015] One object of the invention is to facilitate access to a fluid transfer bearing intended to supply a pitch change mechanism for a fan rotor equipped with the turbine, the fan shaft of the fan rotor being coaxial with the turbine shaft, while minimizing the length of the turbine. Another object is to minimize the volume of the fluid transfer bearing.

[0016] To this end, according to a first aspect, the subject of the invention is a pitch changing mechanism for adjusting the angular position of at least one variably settable blade about a pivot axis of the blade, the pitch changing mechanism comprising:

[0017] - a frame, which is fixed relative to the pivot axis,

[0018] a control actuator comprising a fixed part fixed to the frame and a movable part movable in translation along the longitudinal axis relative to the fixed part between a retracted position and an extended position,

[0019] - a coupling system coupling the movable part to the variable-setting blade to convert a translation of the movable part along the longitudinal axis into a rotation of the variable-setting blade about the pivot axis,

[0020] as well as

[0021] a fluid conveying bearing for supplying an actuating fluid from a source to a control actuator, the control actuator being rotationally movable relative to the source about a longitudinal axis,

[0022] Therein, the control actuator extends at least partially around the fluid conveying bearing.

[0023] According to a particular embodiment of the invention, the pitch changing mechanism further comprises one or more of the following features, employed alone or in any technically possible combination:

[0024] - The control actuator is coaxial with the fluid conveying bearing;

[0025] - the control actuator extends around more than half of the fluid conveying bearing, advantageously around more than three quarters of the fluid conveying bearing;

[0026] - the pitch changing mechanism comprises a pitch locking device adapted to lock the translation of the movable part relative to the fixed part in at least one direction, the pitch locking device comprising:

[0027] o a locking member movable in translation relative to the frame along the longitudinal axis between an operating position and a locking position,

[0028] o biasing means biasing the locking member towards its locked position, and

[0029] o retaining means for retaining the locking member in its operating position under normal operating conditions, the retaining means comprising a balanced actuator comprising a balanced chamber supplied with an actuating fluid to counteract the bias of the biasing means,

[0030] a fluid delivery bearing configured to supply an actuating fluid from a source to the balanced actuator;

[0031] - a fluid conveying bearing comprising a stator and a rotor, the rotor being engaged with the control actuator so as to be movable relative to the stator about a longitudinal axis, the rotor extending around the stator;

[0032] - the fluid conveying bearing comprises a plurality of circuits independent of one another, at least one of said circuits comprising:

[0033] ○Axial channel, the axial channel is formed in the stator,

[0034] o at least one radial aperture formed in the stator and coupling the axial channel to the outer periphery of the stator,

[0035] o a circumferential groove formed between the rotor and the stator and into which the or each radial aperture opens, and

[0036] o at least one radial channel formed in the rotor and extending radially from the groove to a supply passage formed in the frame or between the frame and the fluid conveying bearing;

[0037] - the axial channels of the different circuits are coaxial;

[0038] - the control actuator comprises a first fluid chamber and a second fluid chamber, each containing an actuating fluid for actuating a displacement of the movable part relative to the fixed part, and the fluid conveying bearing comprises a first circuit and a second circuit, the first circuit being fluidically connected to the first fluid chamber for supplying the actuating fluid provided by a source to the first fluid chamber, and the second circuit being fluidically connected to the second fluid chamber for supplying the actuating fluid provided by the source to the second fluid chamber;

[0039] According to a second aspect, another subject of the present invention is a fan rotor for a turbine, the fan rotor comprising a hub and a plurality of variable-setting blades, each variable-setting blade being pivotable relative to the hub about a corresponding pivot axis, the rotor also comprising a pitch changing mechanism according to the first aspect, the pitch changing mechanism being used to adjust the angular position of each of the variable-setting blades about its corresponding pivot axis.

[0040] According to a particular embodiment of the invention, the fan rotor further comprises one or more of the following features, employed alone or in any technically possible combination:

[0041] - the fan rotor comprises a guide bearing for guiding the fan rotor in rotation relative to the turbine nacelle about the longitudinal axis, the inner diameter of the guide bearing being greater than the outer diameter of the fluid conveying bearing;

[0042] as well as

[0043] - The longitudinal axis constitutes the axis of rotation of the rotor.

[0044] According to a third aspect, a further subject of the invention is a turbomachine comprising a fan rotor according to the second aspect.

[0045] According to a particular embodiment of the invention, the turbine also has the following features:

[0046] - The longitudinal axis constitutes the axis of elongation of the turbine.

[0047] According to a fourth aspect, a further subject of the invention is an aircraft comprising at least one turbomachine according to the third aspect.

[0048] According to a fifth aspect, the final subject of the present invention is a method for changing the pitch of blades of a fan rotor of a turbine, each blade being pivotable about a corresponding pivot axis relative to a hub of the fan rotor, the method comprising adjusting the angular position of each of the blades about its corresponding pivot axis by means of a pitch changing mechanism according to the first aspect.

[0049] According to a particular embodiment of the present invention, the method further has the following characteristics:

[0050] - The method comprises the additional step of locking the orientation of the blades by means of pitch locking means. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Other characteristics and advantages of the invention will become apparent on reading the following description given by way of example only and with reference to the accompanying drawings, in which:

[0052] - Figure 1 is a top view of an aircraft according to an exemplary embodiment of the present invention,

[0053] - Figure 2 for Figure 1 A simplified partial cross-sectional view of a turbine of an aircraft,

[0054] - Figure 3 According to the first embodiment Figure 2A simplified cross-sectional view of a portion of a pitch change mechanism of a turbine of FIG. 1 , the pitch change mechanism being in a first configuration,

[0055] - Figure 4 is with Figure 3 A similar view of the pitch changing mechanism in the second configuration,

[0056] - Figure 5 yes Figure 3 The first variant of the pitch changing mechanism is Figure 3 A view similar to the view of

[0057] - Figure 6 yes Figure 3 The second variant of the pitch changing mechanism is Figure 3 A view similar to the view of

[0058] - Figure 7 yes Figure 3 The third variant of the pitch changing mechanism is Figure 3 A view similar to the view of

[0059] - Figure 8 is used to make Figure 2 Simplified view of the radial axis of the rotating arm of the turbine's variable-setting blades,

[0060] - Fig. 9 yes Figure 3 A partial cross-sectional perspective view of the planetary roller screw of the pitch change mechanism,

[0061] - Fig.10 yes Figure 3 Detailed view of the fluid transfer bearing of the pitch change mechanism,

[0062] - Fig.11 According to the second embodiment Figure 2 a simplified cross-sectional view of a portion of the pitch changing mechanism of a turbine, and

[0063] - Fig.12 yes Fig.11 Detailed view of the fluid transport bearing of the pitch change mechanism. DETAILED DESCRIPTION

[0064] Figure 1 The illustrated aircraft 10 includes a turbine 12 for propelling the aircraft.

[0065] In the example shown, the aircraft 10 is an airplane. The aircraft generally comprises a fuselage 14, a tail 16 and two wings 18. Here, the number of turbines 12 is two, and each turbine is housed under a respective wing 18. In a variant (not shown), the turbines 12 are arranged along the fuselage 14 (for example, near the tail 16). Still as a variant (also not shown), the aircraft 10 comprises a single turbine 12 or at least three turbines 12.

[0066] exist Figure 2 One of the turbines 12 is shown in FIG.

[0067] As can be seen in this figure, the turbine 12 extends along a longitudinal axis X. The turbine generally has an angular symmetry about said longitudinal axis X, ie there is at least one angle about which the turbine is rotationally invariant about the longitudinal axis.

[0068] Here and in the rest of the text, the terms "inner" and "outer" and "inner" and "outer" are to be understood with reference to axis X, elements described as "inner" or "inner" elements being oriented toward axis X, while "outer" or "outer" elements are oriented opposite to axis X.

[0069] The turbomachine 12 generally includes a nacelle 20 , an internal air path 22 for circulating air flow through the nacelle 20 , a combustion chamber 24 housed in the air path 22 , an engine body 26 , and a gas exhaust nozzle 28 .

[0070] In the remainder of this document, the terms “upstream” and “downstream” are to be understood with reference to the flow direction of the air flow through the air path 22 .

[0071] The engine body 26 includes a compressor 30, a turbine 32, and a drive shaft 34, which couples the turbine 32 with the compressor 30 to drive the compressor 30 through the turbine 32. The compressor 30 is arranged upstream of the combustion chamber 24, and supplies compressed air to the combustion chamber 24. The turbine 32 is arranged downstream of the combustion chamber 24 and receives exhaust gas leaving the combustion chamber 24.

[0072] The drive shaft 34 has a longitudinal axis X as a rotation axis.

[0073] The drive shaft 34 is rotationally guided relative to the nacelle 20 by means of bearings (not shown).

[0074] In the example shown, the turbomachine 12 is a multi-body turbomachine, in particular a twin-body turbomachine, which includes a low-pressure body 40 in addition to the engine body 26. Thus, the engine body 26 constitutes a high-pressure body, the compressor 30 is a high-pressure compressor, the turbine 32 is a high-pressure turbine, and the drive shaft 34 is a high-pressure shaft.

[0075] The low-pressure body 40 includes a low-pressure compressor 42 , a low-pressure turbine 44 , and a low-pressure shaft 46 that couples the low-pressure turbine 44 to the low-pressure compressor 42 to drive the low-pressure compressor 42 via the low-pressure turbine 44 .

[0076] The low-pressure compressor 42 is arranged upstream of the high-pressure compressor 30 and supplies compressed air to the high-pressure compressor. The low-pressure turbine 44 is arranged downstream of the high-pressure turbine 32 and receives exhaust gas leaving the high-pressure turbine.

[0077] The low-pressure shaft 46 is rotationally guided relative to the nacelle 20 by means of bearings (not shown).

[0078] The low-pressure shaft 46 is coaxial with the high-pressure shaft 34 . Therefore, the low-pressure shaft also has a longitudinal axis X as a rotation axis. In particular, the low-pressure shaft 46 extends inside the high-pressure shaft 34 .

[0079] The turbine 12 also includes a fan 50 to drive the air flow in an outer air flow path 52 around the nacelle 20. Thus, a distinction can be made between a primary air flow A (hot), formed by the portion of the air flow driven through the inner air flow path 22, and a secondary air flow B (cold), formed by the portion of the air flow driven through the outer air flow path 52.

[0080] The fan 50 comprises a fan rotor 54. The fan rotor 54 is rotatably mounted relative to the nacelle 20 about the longitudinal axis X via a guide bearing 53. The fan rotor comprises a hub 55 ( Figure 3 ), the hub is provided with fan blades 56 extending generally radially outward from the hub 55. These blades 56 drive the air flow through the outer air flow path 52 when rotating.

[0081] exist Figure 8 As can be seen in FIG. 5 , 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.

[0082] return Figure 2 , the fan rotor 54 is rotationally driven by the low-pressure turbine 44 via the low-pressure shaft 46. Preferably, this drive is accomplished via a reduction gear (not shown) that enables the fan rotor 54 to rotate at a lower speed than the speed of the low-pressure shaft 46. In a variant (not shown), the drive is direct, i.e. the fan rotor 54 is rotationally fixed to the low-pressure shaft 46.

[0083] In the example shown, the fan 50 also comprises a fan stator 58 comprising stationary blades 59 arranged on the outer periphery of the nacelle 20 in the outer air flow path 52 along a plane orthogonal to the longitudinal axis X. This fan stator 58 is here arranged downstream of the fan rotor 54. In a variant (not shown), the fan 50 comprises a counter-rotating fan rotor instead of a fan stator 58.

[0084] Advantageously, as shown, the fan 50 is of the unducted type, ie the outer air flow path 52 has no peripheral limit. Thus, as shown, the turbomachine 12 is constituted by a turbojet engine with an unducted fan, or in a variant by a turboprop engine. In a variant (not shown), the outer air flow path 52 is defined by the nacelle 20 and by a fan case surrounding the fan 50; thus, the turbomachine 12 is generally constituted by a turbojet engine with a high bypass ratio, the expansion ratio being defined as the ratio of the flow of the secondary flow B (cold) to the flow of the primary flow A (hot).

[0085] In the example shown, the turbine 12 is in particular of the "puller" type, i.e. the fan 50 is arranged upstream of the inner air flow path 22 and also drives the air flow in the inner air flow path. In a variant (not shown), the turbine is of the "pusher" type, i.e. the fan 50 is arranged around the downstream half of the nacelle 20.

[0086] The blades 56 of the fan rotor 54 have a variable arrangement, ie each blade 56 is pivotably mounted relative to the hub 55 about a respective pivot axis P. The pivot axis extends in the direction of elongation of the blade 56. The pivot axis is orthogonal to the longitudinal axis X.

[0087] Each blade 56 is in particular capable of pivoting about the axis P relative to the hub 55 between a so-called feathered position, in which the chord C of the blade 56 is substantially parallel to the longitudinal axis X, and a so-called flat position, in which the chord C of the blade 56 is substantially orthogonal to the longitudinal axis X. Preferably, each blade 56 is also capable of pivoting beyond the flat position, up 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. Since the blades 56 are usually twisted, the chord C, which serves as a measure of the setting angle, is usually formed by the chord of the blade at 75% of the radius of the fan rotor 54.

[0088] For this reason, as in Figure 3 As can be seen in FIG, each blade 56 is fixed to a fastening member 60 arranged at the blade root. The fastening member 60 is rotatably mounted relative to the hub 55 about the pivot axis P. More precisely, the fastening member 60 is rotatably mounted in a housing 62 formed in the hub 55 by means of a ball bearing 64 or other rolling element.

[0089] The fan 50 also comprises a pitch changing mechanism 70 for adjusting the setting angle of each blade 56 about its pivot axis P, so as to adapt the performance of the turbine 12 to different flight phases.

[0090] Now refer to Figures 3 to 9 A first embodiment of the pitch changing mechanism 70 will be described.

[0091] Reference Figure 3 In this first embodiment, the pitch changing mechanism 70 comprises a frame 72 , a control actuator 74 , a system 76 for controlling the control actuator 74 , and a coupling system 78 .

[0092] The frame 72 is fixed to the hub 55 and is generally constituted by a portion of the hub 55. The frame is thus fixed relative to the pivot axis P.

[0093] The frame 72 comprises a base 80. The base 80 is centered on the longitudinal axis X. Here, the base is traversed by the pivot axis P.

[0094] In the example shown, the base 80 delimits a housing 82 open in the downstream direction. This housing 82 is in particular a cylinder of revolution and is centered on the axis X.

[0095] Back to Figure 3 The base 80 also defines a cavity 86 which opens onto an upstream face 88 of the base 80 through an orifice 90 , the orifice being here centred on the axis X. This cavity 86 is in particular cylindrical (generally a cylinder of revolution) and centred on the axis X. The cavity is arranged between the upstream face 88 and the housing 82 .

[0096] The base 80 has a stop 92 oriented downstream. The stop 92 is formed here by a portion of the upstream face 88 . The stop extends substantially radially and is arranged in particular around the orifice 90 .

[0097] In the example shown, the frame 72 also comprises a cylindrical body 94 protruding upstream from the base 80. This cylindrical body 94 is centered on the axis X and opens out to its upstream end 95. The cylindrical body extends around the stop 92. This cylindrical body is generally a cylindrical body of revolution.

[0098] Here, the frame 72 also includes an outer peripheral cylindrical body 96 which is coaxial with the cylindrical body 94 and surrounds the cylindrical body 94 and projects upstream from the base 80. The cylindrical body 96 is open at its upstream end 97. The cylindrical body is generally a cylindrical body of revolution.

[0099] The base 80 and the outer peripheral cylinder 96 together define an outer peripheral surface 88 of the frame 72. The outer peripheral surface 88 is generally cylindrical and is centered on the axis X. The outer peripheral surface is oriented radially outwardly.

[0100] In the variant, Figure 5 As shown, the frame 72 does not include the cylindrical body 94 .

[0101] In another variation, Figure 6 As shown, the frame 72 does not include the peripheral cylinder 96. The outer peripheral surface 88 is thus defined by the base 80 and the cylinder 94.

[0102] Back to Figure 3 The control actuator 74 includes a fixed component 100 and a movable component 102, the fixed component is fixed to the frame 72, and the movable component can be moved along the longitudinal axis X relative to the fixed component 100 in a retracted position (such as Figure 3 as shown) and the extended position (as shown Figure 4 Optionally, the movable component 102 can also be rotated around the longitudinal axis X at a limited angle (eg, about 5°).

[0103] Furthermore, the control actuator 74 is substantially centered on the longitudinal axis X. Thus, the control actuator 74 has the longitudinal axis X as an axis.

[0104] The control actuator 74 comprises in particular a continuous cylinder 104 forming one of the fixed part 100 and the movable part 102 and a piston 106 forming the other of the fixed part 100 and the movable part 102. Here, the cylinder 104 forms the movable part 102 and the piston 106 forms the fixed part 100.

[0105] Thus, in the example shown, the cylinder 104 surrounds and extends coaxially with the outer peripheral surface 88 of the frame 72 , and the piston 106 is constituted by a collar 108 fixed to the frame 72 and extending radially outward from the outer peripheral surface 88 to the cylinder 104 .

[0106] The cylinder 104 defines an inner cavity 110. The piston 106 divides the inner cavity 110 into two adjacent fluid chambers 112, 114. Each fluid chamber contains an actuating fluid, typically consisting of oil, to actuate the displacement of the movable part 102 relative to the fixed part 100. The actuating 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 fluid chamber 112 and the second fluid chamber 114 are arranged so that a relative increase in the first pressure (i.e. an increase relative to the second pressure) drives the piston 110 to displace toward the extended position of the piston, and a relative increase in the second pressure (i.e. an increase relative to the first pressure) drives the piston 110 to displace toward the retracted position of the piston.

[0107] Here, each of the fluid chambers 112, 114 is bounded internally by the outer peripheral surface 88 of the frame 72 and externally by the cylinder 104. In addition, the first fluid chamber 112 is bounded at its downstream end by the piston 106, and the second fluid chamber 114 is bounded at its upstream end by the piston 106.

[0108] The control actuator 74 is also particularly compact, which enables the control actuator to be made lighter.

[0109] exist Figure 3 In the example shown, the movable part 102 also includes an upstream guide bushing 116 and a downstream guide bushing 118, each of which is fixed to the cylinder 104 and extends radially inward from the cylinder 104 to the outer peripheral surface 88 of the frame 72. The upstream guide bushing 116 is arranged upstream of the piston 106 and defines the upstream end of the first fluid chamber 112. The downstream guide bushing 118 is arranged downstream of the piston 106 and defines the downstream end of the second fluid chamber 114.

[0110] exist Figure 3 In the example shown, each of the upstream guide bushing 116 and the downstream guide bushing 118 constitutes a sealing bushing and respectively longitudinally closes the first fluid chamber 112 and the second fluid chamber 114. Thus, the fluid chambers 112, 114 are closed at each of the longitudinal ends of the control actuator 74.

[0111] In the variant, Figure 7 As shown, only the downstream guide bushing 118 constitutes a sealing bushing. The upstream guide bushing 118 itself has a bore 119 enabling the actuating fluid to flow through the upstream guide bushing 118 .

[0112] In another variation, Figure 5 As shown, the movable component 102 does not include any upstream guide bushing 118 .

[0113] Back to Figure 3 The control system 76 includes a pressure generator 130, a pressure control unit 132, and a return line 136. The pressure generator is used to make the actuating fluid reach a third pressure higher than the first pressure and the second pressure. The pressure control unit is used to adjust the pressure of the actuating fluid in the first fluid chamber 112 and the second fluid chamber 114 by the third pressure. The return line is used to discharge the decompressed actuating fluid. The control system 76 also includes a main container 133, an emergency circuit 134, and a command module 135.

[0114] The pressure generator 130 comprises, for example, a pump capable of pumping the fluid to a third pressure, for example 100 bar. When the pressure of the actuating fluid downstream of the pressure generator 130 exceeds the third pressure, the main overpressure valve 139A enables a portion of the actuating fluid to be discharged to the return line 136.

[0115] The pressure control unit 132 is supplied with an actuating fluid at a third pressure by the pressure generator 130. The pressure control unit is fluidly connected to the first fluid chamber 112 and the second fluid chamber 114. The pressure control unit is capable of distributing the actuating fluid between the first fluid chamber 112 and the second fluid chamber 114 to adjust the fluid pressure inside each of these chambers 112, 114, thereby adjusting the position of the piston 110 between the retracted position and the extended position of the piston. The pressure control unit is also capable of discharging the actuating fluid from the first fluid chamber 112 and the second fluid chamber 114 into the return line 136.

[0116] The main tank 133 is configured to collect the reduced pressure actuation fluid from the return line 136. The main tank supplies the pressure generator 130.

[0117] The emergency circuit 134 is capable of supplying actuating fluid to the first fluid chamber 112 to displace the piston 110 toward its extended position in the event of a failure of the pressure generator 130. To this end, the emergency circuit 134 comprises an auxiliary reservoir 137 and an auxiliary pump 138. In the example shown, the emergency circuit also comprises an auxiliary overpressure valve 139B.

[0118] The auxiliary container 137 is configured to collect the reduced pressure actuation fluid from the return line 136. The auxiliary container supplies the auxiliary pump 138. In the example shown, the auxiliary container also supplies the main container 133, and the reduced pressure actuation fluid from the return line 136 is conveyed via the auxiliary container 137 before reaching the main container 133.

[0119] The auxiliary pump 138 is capable of pumping the actuating fluid into the auxiliary reservoir 137 to bring the actuating fluid to a third pressure. The auxiliary pump is fluidically connected to the pressure control unit 132 to supply the actuating fluid at the third pressure to the pressure control unit, and the pressure control unit 132 is configured to redirect all the actuating fluid from the auxiliary pump 138 to the first fluid chamber 112.

[0120] When the pressure of the actuating fluid downstream of the auxiliary pump 138 exceeds the third pressure, the overpressure valve 139B can discharge a portion of the actuating fluid to the return line 136 .

[0121] The command module 135 is configured to receive a setting instruction (not shown) and derive from the setting instruction a command signal that is sent to the pressure control unit 132. In particular, the command module 135 is configured to send a command signal to the pressure control unit 132 that is intended to increase the fluid pressure in the first chamber 112 when the setting instruction has the purpose of increasing the pitch of the blades 56, and to send a command signal to the pressure control unit 132 that is intended to increase the fluid pressure in the second chamber 114 when the setting instruction has the purpose of reducing the pitch of the blades 56.

[0122] The command module 135 is also configured to send a start-up command to the emergency circuit 134 (more specifically, to the auxiliary pump 138 of the emergency circuit) in the event of a failure of the pressure generator 130 .

[0123] The control system 76 is fixed in the reference system of the nacelle 20 . The control actuator 74 is therefore movable in rotation about the longitudinal axis X relative to said control system 76 .

[0124] The coupling system 78 couples the movable part 102 to each blade 56 to convert the translation of the movable part 102 along the longitudinal axis X and, where applicable, the rotation of the movable part 102 about the longitudinal axis X into a rotation of each blade 56 about the pivot axis P of the blade. In particular, the coupling system 78 couples the movable part 102 to each blade 56 to:

[0125] - converting a translation of the movable part 102 in a first direction along the longitudinal axis X into a rotation of the variable-set blade 56 about the pivot axis P towards a flat position, and

[0126] - Converting a translation of the movable part 102 along the longitudinal axis X in a second direction opposite to the first direction into a rotation of the variable-set blade 56 about the pivot axis P towards the feathered position.

[0127] To this end, the coupling system 78 includes a synchronizing ring 140 fixed to the movable part 102 and, for each of the blades 56 , a mechanism 142 for coupling the blade 56 to the synchronizing ring 140 .

[0128] The synchronizer ring 140 extends in a radial plane around the movable component 102. In particular, the synchronizer ring is attached to an upstream end 143 of the movable component 102.

[0129] Each coupling mechanism 142 includes a first hinge 144 fixed to the movable part 102 , a second hinge 146 fixed to the blade 56 away from the pivot axis P of the blade 56 , and a coupling member 148 coupling the first hinge 144 to the second hinge 146 .

[0130] The first joint 144 is carried by the synchronizer ring 140. Here, the first joint is formed by a ball joint.

[0131] The second articulation 146 is also formed by a ball joint. Here, the second articulation is eccentric relative to the pivot axis P.

[0132] The coupling member 148 has a first end 150 hinged to the first hinge 144 and a second end 152 hinged to the second hinge 146. Advantageously, the coupling member 148 is rigid and has an adjustable length, i.e., the distance between the first end 150 and the second end 152 can be varied, which enables the length of the coupling member to be precisely adjusted when stopped so that the setting angle of each blade 56 can be controlled by the pitch change mechanism 70.

[0133] In this case, the coupling component 148 is formed by a rod 153 .

[0134] In the example shown, each coupling mechanism 142 also comprises a crank 154 connecting the fastening part 60 to the second hinge 146. This crank 154 is rigid and fixed to the fastening part 60. The crank extends at least partially in a direction orthogonal to the pivot axis P. The crank forms an arm for rotating the blade 56.

[0135] exist Figure 3 In the example shown, the first direction extends from upstream to downstream, i.e., the displacement of the movable member 102 towards the stop 92 (in other words, towards the retracted position of the movable member) drives each blade 56 to rotate towards the flat position of the blade, and the second direction extends from downstream to upstream, i.e., the displacement of the movable member 102 away from the stop 92 (in other words, towards the extended position of the movable member) drives each blade 56 to rotate towards the feathered position of the blade. In addition, the first hinge 144 is arranged upstream of the second hinge 146.

[0136] For this reason, as in Figure 8 It can be seen in FIG. 1 that the second hinge 146 is arranged opposite the trailing edge 57B relative to a plane Q which is orthogonal to the chord C and contains the pivot axis P.

[0137] This particular arrangement enables the natural stress of the blade 56 towards its flat position to cause the coupling member 148 to work under traction rather than compression when the pitch change mechanism 70 is fixed. Therefore, the risk of buckling of the coupling member 148 is very low, enabling the use of a coupling member 148 with relatively low resistance, thereby making the pitch change mechanism 70 lightweight.

[0138] The pitch changing mechanism 70 further comprises a pitch locking device 160 adapted to lock a translation of the movable part 102 of the control actuator 74 in a first direction, ie here towards the retracted position of the movable part.

[0139] The locking device 160 includes a support member 162 and a screw-nut system 164 .

[0140] The support member 162 can be in an operating position ( Figures 3 to 7 The support member 162 is translated in a first direction (i.e., in a locked position) and a locked position (not shown). Figure 3 In the example shown, the support member 162 is displaced from its operating position to its locking position by translation from upstream to downstream. In other words, the operating position of the support member 162 is arranged upstream of the locking position of the support member.

[0141] The support member 162 comprises a body 166 extending along the longitudinal axis X and centered on the longitudinal axis X. The body 166 has a first longitudinal end 168 (in particular a downstream longitudinal end) and a free second longitudinal end 170, the first longitudinal end being engaged by the orifice 90 of the frame 72. Here, the body 166 is solid.

[0142] The first longitudinal end 168 and the aperture 90 of the frame 72 together form a guide system 172 for guiding the support member 162 relative to the frame 72 . The guide system 172 is arranged here on the downstream side of the screw-nut system 164 .

[0143] The support member 162 also includes a skirt 174 secured to the body 166 and disposed about the second longitudinal end 170 of the body 166 .

[0144] The screw-nut system 164 includes a screw 176 and a nut 178 .

[0145] The screw 176 extends around the body 166 of the support member 162 and is coaxial with said body 166. The screw is fixed in translation to the support member 162 and is movably mounted to rotate relative to the support member 162 about the longitudinal axis X. To this end, the screw 176 is assembled on the support member 162 by means of a bearing 180. This bearing 180 is here arranged between the skirt 174 of the support member 162 and an end portion 182 of the screw 176, which end portion of the screw is housed between the body 166 and the skirt 174.

[0146] The screw 176 has a second longitudinal end portion 184 opposite the end portion 182. The second longitudinal end portion 184 defines a radial stop surface 186. The stop surface 186 is away from the frame 72 when the support member 162 is in the operating position, and the stop surface bears against the stop portion 92 of the frame 72 when the support member 162 is in the locked position.

[0147] Here, the second longitudinal end portion 184 expands from the threaded body 190 of the screw 176 up to the stop surface 186. As a result, the contact surface between the stop surface 186 and the stop 92 increases, which increases the friction between the stop surface 186 and the stop 92 and enables better transmission of braking and locking forces.

[0148] The stop surface 186 and the stop portion 92 are both smooth here. In a variant (not shown), the stop surface 186 and / or the stop portion 92 have roughness to further increase the friction between the stop surface 186 and the stop portion 92 and enable a better transmission of force.

[0149] In particular, the stop surface 186 extends generally radially. The stop surface is oriented in a first direction, i.e., in Figure 3 In the example shown, it is oriented downstream. Here, the stop surface is formed at the downstream end of the screw 176.

[0150] The threaded body 190 extends from one of the end portions 182, 184 to the other end portion. The threaded body has external threads 192 on its circumference.

[0151] The threaded body 190 and the nut 178 are received within the cylindrical body 94 of the frame 72 .

[0152] The nut 178 is fixed to the movable part 102 of the control actuator 74 and is coaxial with the screw 176. The nut interacts with the screw 176 so that translation of the nut 178 along the longitudinal axis X relative to the screw 176 drives the screw 176 to rotate about the longitudinal axis X relative to the support member 162.

[0153] The nut 178 has an internal thread 194 .

[0154] The screw-nut system 164 is in particular formed by a reversible planetary roller screw system 195. Typically, in addition to the screw 176 and the nut 178, this planetary roller screw system 195 comprises a plurality of rollers 196 arranged between the screw 176 and the nut 178, each roller 196 extending parallel to the longitudinal axis X.

[0155] like Fig. 9 As shown, each roller 196 has threads 198 that engage with the external threads 192 of the screw 176 and the internal threads 194 of the nut 176. Each roller also includes external teeth 199 located at the end of the roller and extending from the journal 200.

[0156] Typically, the planetary roller screw system 195 also has means 202 for guiding and retaining the rollers 196. The guide and retaining means 202 comprise a roller carrier 204 (also called a spacer ring) mounted coaxially with the screw 176 between the screw and the nut 178, the roller carrier having a recess 206 which receives the journal 200 of the roller 196. The guide and retaining means also comprise a synchronizing tooth 210 in which the external teeth 198 located at the respective ends of the rollers 196 mesh. This meshing of the external teeth 198 in the synchronizing teeth 210 forms a planetary gear whose function is to ensure the synchronization of the planetary motion (also called epicyclic motion) of the rollers 196, thereby simplifying the motion of the rollers 196 by helping them to roll easily on the threads 192 of the screw 176 and the threads 194 of the nut 178 with as little slippage as possible.

[0157] In the example shown, the planetary roller screw system 195 is of standard type, with the rollers 196 fixed in translation to the nut 178. The synchronizing teeth 210 are constituted by the internal teeth of a ring 208 fixed to the nut 178 and mounted respectively at each longitudinal end of the nut 178, the longitudinal extension of the nut being substantially equal to that of the threaded portion of the rollers 196 and less than that of the threaded body 190 of the screw 176.

[0158] In a variant (not shown), the planetary roller screw system 195 is of the inverted type, the rollers 196 being fixed in translation to the screws 176. The synchronous teeth 210 are thus constituted by two external teeth of the screw 176 at each longitudinal end of the threaded body 190, the longitudinal extension of which is substantially equal to the longitudinal extension of the threaded portion of the rollers 196 and less than the longitudinal extension of the nut 178.

[0159] As another variant, the planetary roller screw system 195 consists of a recycling roller screw system (for example, the recycling roller screw system described in document EP 275504 A2), or of a roller bearing screw system (for example, the roller bearing screw system described in document EP 168942 A1 or the roller bearing screw system described in document EP 671 070 A1).

[0160] This feature enables good transmission of the force of the nut 178 to the screw 176 via the screw-nut system 164, while maintaining a small pitch in the helical coupling of the screw-nut system 164. In particular, in the case of rotational locking of the screw 176, this makes it possible to fix the nut 178 relative to the screw 176 even without a separate locking nut. Thus, the use of a separate locking nut can be omitted, which simplifies the manufacture of the mechanism and reduces costs, while increasing the reliability of the mechanism and minimizing the mass of the mechanism.

[0161] In a variant (not shown), the screw-nut system 164 consists of a screw-nut system similar to the one described in EP 1 832 509 .

[0162] return Figure 3 In the example shown in the figure, the pitch lock device 160 is located outside the fluid chambers 112, 114 of the control actuator 74. This arrangement enables the pitch lock device 160 and the control actuator 74 to be assembled on the frame 72 independently of each other, which facilitates the installation of the pitch change mechanism 70 and thus reduces costs.

[0163] exist Figure 3 , a portion of the pitch lock device 160 even extends longitudinally away from the control actuator 74. In other words, there is a radial plane beyond which a portion of the pitch lock device 160 extends, while the control actuator 74 does not extend beyond said radial plane. In particular, said portion of the pitch lock device 160 extends upstream of the control actuator 74.

[0164] In order to enable such an arrangement to be formed, the pitch locking device 160 comprises a collar 193 which connects the nut 178 to the movable part 102 of the control actuator 74. This collar 193 here protrudes longitudinally upstream from the control actuator 74. In particular, the collar is frustoconical, the diameter of which decreases from a downstream end 193A of the collar attached to the control actuator 74 to an upstream end 193B of the collar attached to the nut 178.

[0165] exist Figure 3In the example shown, the pitch lock 160 also forms a cantilever in the longitudinal direction relative to the frame 72. In other words, the entire portion of the frame 72 that supports the lock 160 is longitudinally located on the same side (here downstream) of the lock 160; the lock 160 is not longitudinally surrounded by the portion of the frame 72 that supports the lock. This arrangement omits the use of a support arranged upstream of the lock 160, which facilitates access to the pitch change mechanism 70, in particular to the coupling system 78.

[0166] Therefore, in Figure 3 In the example shown, the control actuator 74 is arranged longitudinally on the same side of the nut 178 as the guide 172 and the stop 92 (here the downstream side).

[0167] In order to provide good support for the locking device 160 even in the case of cantilevering, the pitch change mechanism 70 comprises a device 220 for guiding the nut 178 relative to the frame 72. The guiding device 220 comprises an inner cylinder 222 fixed to the nut 178 and an outer cylinder 224 fixed to the frame 72, the inner cylinder 222 interacting with the outer cylinder 224 to slide longitudinally inside the outer cylinder.

[0168] In particular, the nut 178 is mounted on an inner surface 226 of the inner cylindrical body 222. The inner cylindrical body 222 has an upstream end 228 to which the upstream end 193B of the ferrule 193 is attached.

[0169] Here, the outer cylindrical body 224 is formed by the cylindrical body 94 of the frame 72 .

[0170] The pitch lock device 160 requires lubrication. To this end, the lock device 160 comprises a housing 230 which at least partially defines an enclosure for the circulation of a lubricating fluid for the pitch lock device 160. This housing 230 is fixed to the nut 178 and surrounds the nut 178, the screw 176 and the support member 162.

[0171] exist Figure 3 , Figure 4 and Figure 6In the example of , the housing 230 includes an inner cylinder 222 and a cover 232, the cover closing one end (here, the upstream end 228) of the inner cylinder 222 opposite to the frame 72. The inner cylinder 222 has a seal 234 on its outer periphery that contacts the inner surface 236 of the outer cylinder 224. Therefore, the outer cylinder 224 and the housing 230 together define a capsule 238 for the circulation of the lubricating fluid of the locking device 160. The capsule 238 is fluidically isolated from the fluid chambers 112, 114 of the control actuator 74 by the seal 234 and the upstream guide bushing 116. Therefore, the seal 234 and the guide bushing 116 form a seal of the pitch change mechanism 70, and the seal of the pitch change mechanism fluidly isolates the fluid chambers 112, 114 of the control actuator 74 from the pitch locking device 160.

[0172] Advantageously, the lubricating fluid of the locking device 160 consists of oil. Thus, the pitch locking device 160 comprises an accumulation (not shown) making it possible to store lubricating fluid when the control actuator 74 is in the retracted position and to deliver the lubricating fluid to the enclosure 238 when the control actuator 74 is displaced towards its extended position. As a variant, the lubricating fluid of the locking device 160 consists of grease deposited on the screw 176 and on the balls of the bearing 180.

[0173] exist Figure 5 (wherein the outer cylinder 224 and the upstream guide bushing 116 are not present) and Figure 7 (where the inner cylinder 222 and the upstream guide bushing 116 are bored), the housing 230 is composed of the collar 193 and the cover 239 that closes the upstream end 193B of the collar 193. Therefore, the first fluid chamber 112 is in fluid communication with the interior of the housing 230, and the actuating fluid forms the lubricating fluid of the locking device 160.

[0174] This variant makes it possible to dispense with the use of an accumulation section. However, this variant does require a Figure 3 , Figure 4 and Figure 6 A variation of the flow rate pump 130 has a higher flow rate.

[0175] The locking device 160 further includes a biasing device 240 that biases the support member 162 into the locked position of the support member and a retaining device 242 that is used to retain the support member 162 in the operating position of the support member when the pitch changing mechanism 70 is in normal operating conditions.

[0176] The biasing means 240 here consists of a compression spring which is compressed between the frame 72 and a shoulder 244 fixed to the support member 162. The biasing means is housed in the cavity 86, in particular between the shoulder 244 and the orifice 90.

[0177] The retaining device 242 includes a balancing actuator 250 including a balancing piston 252 and a balancing chamber 254 .

[0178] The balancing piston 252 is movably mounted in translation relative to the frame 72 along the longitudinal axis X. The balancing piston is in particular coaxial with the support member 162 . In the example shown, the balancing piston is arranged in the longitudinal extension of the support member 162 , between the support member 162 and the balancing chamber 254 .

[0179] The balancing chamber 254 is defined between the balancing piston 252 and the frame 72. In particular, the balancing chamber 254 is defined between the balancing piston 252 and a bottom 255 of the cavity 86 opposite the orifice 90; therefore, the guide system 172, the biasing device 240 and the retaining device 242 are all longitudinally arranged on the same side (here the downstream side) of the screw-nut system 164 (in particular the nut 178).

[0180] The balancing chamber 254 is fluidically connected to the pressure generator 130 via a fluid connection circuit 256 so as to be supplied with the actuating fluid at a third pressure. The balancing chamber is intended to counteract the bias of the biasing device 240 when this supply is active.

[0181] To this end, the balancing actuator 250 is arranged so that the pressure exerted on the piston 252 by the fluid contained in the chamber 254 is directed in a direction opposite to the biasing direction of the biasing device 240: in the example shown, the balancing piston 252 is arranged between the chamber 254 and the shoulder 244, and the shoulder 244 is arranged between the piston 252 and the biasing device 240. In addition, the balancing piston 252 and the balancing chamber 254 are dimensioned so that when the chamber 254 is supplied with an actuating fluid at a third pressure, the force exerted by the actuating fluid on the piston 252 is greater than the biasing pressure on the biasing device 240.

[0182] Thus, when the actuating fluid at the third pressure is supplied to the chamber 254, the bias of the biasing device 240 is removed and the support member 162 remains in the operating position.

[0183] In the example shown, the pressure control unit 132 is fluidly disposed between the pressure generator 130 and the fluid connection circuit 256. The pressure control unit has a first configuration in which the pressure control unit isolates the fluid connection circuit 256 from the return line 136 and a second configuration in which the pressure control unit fluidly connects the fluid connection circuit 256 to the return line 136.

[0184] The pressure control unit 132 is configured to normally be in a first configuration of the pressure control unit, and to switch to a second configuration of the pressure control unit upon receiving a command instruction sent by the command module 135 .

[0185] Still refer to Figure 3 , the pitch changing mechanism 70 finally comprises a fluid transport bearing 257 intended to supply the control actuator 74 with actuating fluid coming from the control system 76 .

[0186] To this end, fluid transfer bearing 257 is configured to transfer actuating fluid from a fixed reference frame attached to nacelle 20 to a rotating reference frame attached to fan rotor 54 , and more specifically to first and second chambers 112 , 114 of control actuator 74 .

[0187] For this purpose, refer to Fig.10 The fluid transfer bearing 257 includes a stator 258 fixed relative to the nacelle 20 and a rotor 259, the stator being fixed relative to the nacelle 20 and the rotor being movably engaged with the fan rotor 54 (and therefore with the control actuator 74) about the longitudinal axis X. The fluid transfer bearing also includes a first circuit 260 and a second circuit 261, the first circuit being fluidically connected to the first fluid chamber 112 to supply the first fluid chamber 112 with an actuating fluid supplied by the control system 76, and the second circuit being fluidically connected to the second fluid chamber 114 to supply the second fluid chamber 114 with an actuating fluid provided by the control system 76.

[0188] The stator 258 is in the shape of a cylinder of revolution (in particular in the form of a solid cylinder) coaxial with the longitudinal axis X. The stator is coupled to the structure 263 ( Figure 3 ).

[0189] The rotor 259 is in the shape of a cylinder of revolution coaxial with the longitudinal axis X. The rotor extends around the stator 258. The outer periphery of the rotor is in contact with the frame 72. The rotor is rotationally guided relative to the stator 258 about the axis X by means of a bearing 264 arranged between the rotor 259 and the stator 258.

[0190] The fluid transfer bearing 257 is therefore coaxial with the axis X. The fluid transfer bearing is therefore also coaxial with the control actuator 74 .

[0191] The first circuit 260 includes: a first axial channel 265A, which is formed in the stator 258; a plurality of first radial orifices 265B (only one of the plurality of first radial orifices is shown here), which are formed in the stator 258 and connect the axial channel 265A to the outer periphery of the stator 258; a first circumferential groove 265C, which is formed between the rotor 259 and the stator 258 and each radial orifice 265B leads to the first circumferential groove; and a plurality of first radial channels 265D, which are formed in the rotor 259 and extend radially from the groove 265C to the first supply passage 266 formed in the frame 72 of the first fluid chamber 112.

[0192] The first axial channel 265A has an axial direction parallel to the axis X. In the example shown, the first axial channel is in particular straight and coaxial with the axis X. In a variant (not shown), the first axial channel 265A is curved and / or also has a radial extension in a direction orthogonal to the axis X.

[0193] Furthermore, in the example shown, the first axial channel 265A has an annular radial cross-section, ie the first axial channel is solid at its center.

[0194] Each first radial orifice 265B has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each first radial orifice 265B is straight in particular along the radial direction. In a variant (not shown), at least the first radial orifice 265B is curved and / or also has an axial extension parallel to the axis X.

[0195] The first circumferential groove 265C extends parallel to a radial plane orthogonal to the axis X.

[0196] Each first radial channel 265D has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each first radial channel 265D is straight in particular along the radial direction. In a variant (not shown), at least the first radial channel 265D is curved and also has an axial extension parallel to the axis X and / or a circumferential extension along a direction orthogonal to the axis X and the radial direction.

[0197] The first supply passage 266 extends from the outlet of the first radial channel 265D as far as the inlet of the first fluid chamber 112. In the example shown, the first supply passage is substantially straight and extends substantially parallel to the axis X.

[0198] The second circuit 261 includes: a second axial channel 267A, which is formed in the stator 258; a plurality of second radial apertures 267B (only one of the plurality of second radial apertures is shown here), which are formed in the stator 258 and connect the axial channel 267A to the outer periphery of the stator 258; a second circumferential groove 267C, which is formed between the rotor 259 and the stator 258 and each radial aperture 267B leads to the second circumferential groove; and a plurality of second radial channels 267D, which are formed in the rotor 259 and extend radially from the groove 267C to a second supply passage 268 formed in the frame 72 of the second fluid chamber 114.

[0199] The second axial channel 267A has an axial extension parallel to the axis X. Advantageously, the second axial channel is coaxial with the first axial channel 265A. In the example shown, the second axial channel is in particular straight and coaxial with the axis X. In a variant (not shown), the second axial channel 267A is curved and / or also has a radial extension in a direction orthogonal to the axis X.

[0200] Furthermore, in the example shown, the second axial channel 267A has an annular radial cross section, ie the second axial channel is solid at its center. Here, the second axial channel extends around the first axial channel 265A.

[0201] Each second radial orifice 267B has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each second radial orifice 267B is straight in particular along the radial direction. In a variant (not shown), at least the second radial orifice 267B is curved and / or also has an axial extension parallel to the axis X.

[0202] Each second radial orifice 267B is here arranged axially downstream of a first radial orifice 265B.

[0203] The second circumferential groove 267C extends parallel to a radial plane orthogonal to the axis X. Here, the second axial groove is arranged axially downstream of the first circumferential groove 265C.

[0204] Each second radial channel 267D has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each second radial channel 267D is straight in particular along the radial direction. In a variant (not shown), at least the second radial channel 267D is curved and also has an axial extension parallel to the axis X and / or a circumferential extension along a direction orthogonal to the axis X and the radial direction.

[0205] Here, each second radial passage 267D is arranged axially downstream of the first radial passage 265D.

[0206] The second supply passage 268 extends from the outlet of the second radial channel 266D as far as the inlet of the second fluid chamber 114. In the example shown, the second supply passage is substantially straight and extends substantially parallel to the axis X.

[0207] The first circuit 260 and the second circuit 261 are independent circuits, ie, the first circuit and the second circuit are not in fluid communication with each other.

[0208] Here, the fluid delivery bearing 257 is also configured to supply the actuating fluid from the control system 76 to the balancing actuator 250. To this end, the fluid delivery bearing 257 includes a third circuit 269 that is independent of the first circuit 260 and the second circuit 261.

[0209] The third circuit 261 includes: a third axial channel 270A, which is formed in the stator 258; a plurality of third radial apertures 270B (only one of the plurality of third radial apertures is shown here), which are formed in the stator 258 and connect the axial channel 270A to the outer periphery of the stator 258; a third circumferential groove 270C, which is formed between the rotor 259 and the stator 258 and each radial aperture 270B leads to the third circumferential groove; and a plurality of third radial channels 270D, which are formed in the rotor 259 and extend radially from the groove 267C to a third supply passage 271 of the balancing actuator 250 formed in the frame 72.

[0210] The third axial channel 270A has an axial extension parallel to the axis X. Advantageously, the third axial channel is coaxial with the first axial channel 265A and the second axial channel 267A. In the example shown, the third axial channel is in particular straight and coaxial with the axis X. In a variant (not shown), the third axial channel 270A is curved and / or also has a radial extension in a direction orthogonal to the axis X.

[0211] Furthermore, in the example shown, the third axial channel 270A has a solid radial cross section. Here, the third axial channel extends in the center of the first axial channel 265A and the second axial channel 267A.

[0212] Each third radial orifice 270B has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each third radial orifice 270B is straight in particular along the radial direction. In a variant (not shown), at least the third radial orifice 270B is curved and / or also has an axial extension parallel to the axis X.

[0213] Each third radial orifice 270B is here arranged axially upstream of the first radial orifice 265B and the second radial orifice 267B.

[0214] The third circumferential groove 270C extends parallel to a radial plane orthogonal to the axis X. Here, the third circumferential groove is arranged axially upstream of the first circumferential groove 265C and the second circumferential groove 267C.

[0215] Each third radial channel 270D has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each third radial channel 270D is straight in particular along the radial direction. In a variant (not shown), at least one third radial channel 270D is curved and also has an axial extension parallel to the axis X and / or a circumferential extension along a direction orthogonal to the axis X and the radial direction.

[0216] Each third radial channel 270D is here arranged axially upstream of the first radial orifice 265D and the second radial orifice 267D.

[0217] The third supply passage 271 extends from the outlet of the third radial channel 266D to the inlet of the balancing chamber 254. In the example shown, the third supply passage comprises a straight axial portion and a diametrical portion, the straight axial portion extending upstream from the outlet of the third radial channel 266D substantially parallel to the axis X to one end of the straight axial portion, and the diametrical portion extending from the upstream end of the axial portion substantially orthogonal to the axis X to the inlet of the balancing chamber 254.

[0218] return Figure 3 The outer diameter of the guide bearing 257 is smaller than the inner diameter of the guide bearing 53 of the fan rotor 54. The guide bearing is arranged upstream of the reduction gear and is specifically accommodated in an accommodation portion 82 defined by the base 80.

[0219] Therefore, the guide bearing 257 is at least partially surrounded by the control actuator 74. In particular, the control actuator 74 extends around more than half of the fluid conveying bearing 257 (advantageously around more than three quarters of the fluid conveying bearing) along the axis X. In order to achieve this measurement, the axial ends of the control actuator 74 and the axial ends of the guide bearing 257 are considered, which are defined as follows:

[0220] - for the control actuator 74 , the axial ends of the control actuator are constituted by the limits of the trajectory of the movable part 102 ;

[0221] - For the guide bearing 257, the axial ends of the guide bearing are constituted by the limits beyond which the rotor 259 and the stator 258 no longer coexist (i.e., starting from the center of the guide bearing, the first axial end of the rotor 259 or the first axial end of the stator 258 encountered defines the axial ends of the guide bearing 257).

[0222] A method for changing the pitch of the blades 56 implemented by the pitch changing mechanism 70 according to the first embodiment will now be described.

[0223] During a first step of the method, the command module 135 first receives a setting instruction aimed at increasing the pitch of the blade 56. Then, the command module 135 sends a command signal to the pressure control unit 132 aimed at increasing the fluid pressure in the first chamber 112. Due to the increase in the fluid pressure in the first chamber 112, the movable part 102 of the control actuator 74 is displaced in the second direction toward its extended position, which drives the blade 56 to pivot toward a large pitch, i.e., toward the feathered position, through the coupling system 78.

[0224] Once the movable member 102 reaches the equilibrium position, the movable member stabilizes and the blades 56 maintain a fixed orientation.

[0225] During the second step of the pitch change method, the command module 135 first receives a setting instruction aimed at reducing the pitch of the blade 56. Then, the command module 135 sends a command signal to the pressure control unit 132 aimed at increasing the fluid pressure in the second chamber 114. Due to the increase in the fluid pressure in the second chamber 114, the movable part 102 of the control actuator 74 is displaced in a first direction towards its retracted position, which drives the blade 56 to pivot towards a small pitch, i.e. towards a flat position, through the coupling system 78.

[0226] Once the movable member 102 reaches the equilibrium position, the movable member stabilizes and the blades 56 maintain a fixed orientation.

[0227] Optionally, the pitch changing method further comprises, after the first step or the second step, a step of commandably locking the orientation of the blade 56 .

[0228] During this step, the command module 135 sends a pitch lock command to the pressure control unit 132. Under the effect of this command, the pressure control unit 132 fluidically connects the fluid connection circuit 256 to the return line 136, causing a decrease in the fluid pressure in the balance chamber 254. As a result, the fluid pressure in the chamber 254 is insufficient to offset the bias on the biasing device 240, which therefore drives the support member 162 to shift to its locked position.

[0229] During this displacement, the screw 176 rotates around the longitudinal axis X while translating under the action of the resistance exerted by the assembly of the nut 178 and the roller 194 (the assembly of the nut and the roller is kept from moving in translation by the control actuator 74) until the stop surface 186 of the screw bears against the stop portion 92 of the frame 72, thereby locking the rotation of the screw 176 around the longitudinal axis X and the translation of the screw along the same axis X.

[0230] Thus, even in the event of a loss of fluid pressure in the same chamber 112 , the vanes 56 are locked in the vane's orientation.

[0231] In the event of a loss of pressure only in the second chamber 114, the movable part 102 of the control actuator 74 is displaced in the second direction under the effect of the pressure difference between the two chambers 112, 114, thereby driving the screw 176 and the support member 162 by this displacement, the support member finding its operating position. The movable part 102 is therefore no longer fixed and can continue to be displaced in the second direction until the blade 56 returns to the feathered position.

[0232] In the event of a failure of the control system 76 (typically, in the event of a failure of the pressure generator 130 ), the pitch variation method includes an additional step of non-commanded locking of the orientation of the blades 56 .

[0233] During this step, a failure of the control system 76 causes the fluid pressure in the balancing chamber 254 to drop, typically because the pressure generator 130 is no longer able to bring the actuating fluid to the third pressure. As a result, the fluid pressure in the chamber 254 is insufficient to offset the bias of the biasing device 240, which drives the support member 162 to shift to its locked position.

[0234] During this displacement, the screw 176 drives the nut 178 and the roller 194 through this displacement, which are no longer kept from moving in translation due to the loss of supply of the control actuator 74. The blade 56 is therefore pivoted very slightly towards the small pitch until the stop surface 186 of the screw 176 bears against the stop 92 of the frame 72, thereby locking the screw 176 in rotation about the longitudinal axis X and in translation along the same axis X.

[0235] The blade 56 is thus prevented from pivoting towards a low pitch by the locking device 160 .

[0236] The non-commanded locking step is followed by a safety protection step of the fan 50. During this step, the emergency circuit 134 is activated and supplies actuating fluid to the first fluid chamber 112 to increase the fluid pressure in this chamber. Under the effect of this pressure increase, the movable part 102 is displaced in the second direction, thereby driving the screw 176 and the support member 162 by this displacement, and the support member returns to its operating position. Therefore, the movable part 102 is no longer fixed and can continue to be displaced downstream until the blade 56 returns to the feathered position.

[0237] Note that these different steps can be performed independently of each other.

[0238] Now refer to Fig.11 A second embodiment of the pitch changing mechanism 70 will be described.

[0239] In this embodiment, pitch changing mechanism 70 includes a frame 272 , a control actuator 274 , a system 276 for controlling control actuator 274 , and a coupling system 278 .

[0240] The frame 272 is fixed to the hub 55 and is generally constituted by a portion of the hub 55. The frame is thus fixed relative to the pivot axis P.

[0241] In the example shown, the frame 272 comprises an upstream assembly 280 and a downstream assembly 282 spaced apart from one another along the longitudinal axis X. Each of these assemblies 280 , 282 is centered on the longitudinal axis X and extends from the longitudinal axis X up to the housing 62 , the upstream assembly 280 being arranged upstream of the housing 62 and the downstream assembly 282 being arranged downstream of the housing 62 .

[0242] The upstream assembly 280 is formed in particular by an upstream flange 284 of substantially dome shape which houses at its center a blind cylinder 286. The blind cylinder 286 is closed at its upstream end 288 and is open at its downstream end 289. The blind cylinder projects upstream relative to the flange 284.

[0243] The upstream component 280 has an orifice 290 in its center that is open to the downstream. This orifice 290 is formed in particular in the upstream end 288 of the blind cylindrical body 286. The upstream component 280 also has a stop 291 that is oriented downstream. This stop 291 is formed here in the downstream face of the upstream end 288 of the blind cylindrical body 286. The stop extends substantially radially and is arranged in particular around the orifice 290.

[0244] Here, the downstream assembly 282 comprises a downstream flange 292 which houses at its center two concentric cylinders 294, 296: a central cylinder 294 which is closed at its upstream end 298 and a peripheral cylinder 296 which surrounds the central cylinder 294 and delimits with the central cylinder 294 a peripheral cavity 300 which is closed at its downstream end 302. The central cylinder 294 defines a housing 304.

[0245] The control actuator 274 includes a fixed component 308 and a movable component 309, the fixed component is fixed to the frame 72, and the movable component can be moved relative to the fixed component 308 along the longitudinal axis X in a retracted position (such as Fig.11 The movable part 309 can be moved in translation between a longitudinal position (shown) and an extended position (not shown). Optionally, the movable part 309 can also be moved in rotation around the longitudinal axis X at a limited angle (for example, about 5°).

[0246] The control actuator 274 notably comprises a piston 310 forming a movable part 309 .

[0247] The control actuator 274 also includes a first fluid chamber 312 and a second fluid chamber 314, each of which is defined between the control piston 310 and the frame 272. The fluid chambers 312, 314 each contain an actuating fluid, typically composed of oil, at a first pressure in the first fluid chamber 312 and at a second pressure in the second fluid chamber 314. The first fluid chamber 312 and the second fluid chamber 314 are arranged so that a relative increase in the first pressure (i.e., an increase relative to the second pressure) drives the piston 310 to shift toward the retracted position of the piston, and a relative increase in the second pressure (i.e., an increase relative to the first pressure) drives the piston 310 to shift toward the extended position of the piston.

[0248] In the example shown, the piston 310 comprises a downstream sealing and guiding bushing 316, an upstream sealing and guiding bushing 318 and a cylindrical body 320 extending from the downstream sealing and guiding bushing 316 to the upstream sealing and guiding bushing 318. The downstream sealing and guiding bushing 316 is housed in the peripheral cavity 300 and extends from the central cylinder 294 to the peripheral cylinder 296, while forming a seal with each of these cylinders 294, 296. The upstream sealing and guiding bushing 318 is housed in the blind cylinder 286 and forms a seal with the peripheral wall 322 of the blind cylinder 286. Thus, the first fluid chamber 312 is delimited at its downstream end by the downstream sealing and guiding bushing 316, at its upstream end by the upstream end 288 of the blind cylinder 286, and at its periphery by the body 320 of the piston 310 and the peripheral wall 322 of the blind cylinder 286. At the same time, the second fluid chamber 314 is constituted by the portion of the peripheral cavity 300 situated between the downstream sealing and guide bushing 316 and the downstream end 302 of said peripheral cavity 300 .

[0249] The control system 276 includes a pressure generator 330, a pressure control unit 332, and a return line 336. The pressure generator is used to make the actuating fluid reach a third pressure greater than the first pressure and the second pressure. The pressure control unit is used to adjust the pressure of the actuating fluid in the first fluid chamber 312 and the second fluid chamber 314 by the third pressure. The return line is used to discharge the decompressed actuating fluid. The control system 276 also includes a main container 333, an emergency circuit 334, and a command module 335.

[0250] The pressure generator 330 comprises, for example, a pump capable of pumping the fluid to a third pressure, for example 100 bar. When the actuating fluid downstream of the pressure generator 330 exceeds the third pressure, the main overpressure valve 339A enables a portion of the actuating fluid to be discharged towards the return line 336.

[0251] The pressure control unit 332 is supplied with the actuating fluid at the third pressure by the pressure generator 330. The pressure control unit is fluidly connected to the first fluid chamber 312 and the second fluid chamber 314. The pressure control unit is capable of distributing the actuating fluid between the first fluid chamber 312 and the second fluid chamber 314 to adjust the fluid pressure inside each of these chambers 312, 314, thereby adjusting the position of the piston 310 between the retracted position and the extended position of the piston. The pressure control unit is also capable of discharging the actuating fluid from the first fluid chamber 312 and the second fluid chamber 314 through the return line 336.

[0252] The main container 333 is configured to collect the reduced pressure actuation fluid from the return line 336. The main container supplies the pressure generator 330.

[0253] The emergency circuit 334 is capable of supplying actuating fluid to the second fluid chamber 314 to displace the piston 310 toward its retracted position in the event of a failure of the pressure generator 330. To this end, the emergency circuit 334 comprises an auxiliary reservoir 337 and an auxiliary pump 338. In the example shown, the emergency circuit also comprises an auxiliary overpressure valve 339B.

[0254] The auxiliary container 337 is configured to collect the reduced pressure actuation fluid from the return line 336. The auxiliary container supplies the auxiliary pump 338. In the example shown, the auxiliary container also supplies the main container 333, and the reduced pressure actuation fluid from the return line 336 is conveyed via the auxiliary container 337 before reaching the main container 333.

[0255] The auxiliary pump 338 is capable of pumping the actuating fluid into the auxiliary reservoir 337 to bring the actuating fluid to a third pressure. The auxiliary pump is fluidically connected to the pressure control unit 332 so as to supply the actuating fluid at the third pressure to the pressure control unit, and the pressure control unit 332 is configured to redirect all the actuating fluid from the auxiliary pump 338 to the second fluid chamber 314.

[0256] When the pressure of the actuating fluid downstream of the auxiliary pump 338 exceeds the third pressure, the overpressure valve 339B is able to discharge a portion of the actuating fluid towards the return line 336 .

[0257] The command module 335 is configured to receive a setting instruction (not shown) and derive a command signal from the setting instruction to be sent to the pressure control unit 332. In particular, the command module 335 is configured to send a command signal to the pressure control unit 332 that is intended to increase the fluid pressure in the second chamber 314 when the setting instruction has the purpose of increasing the pitch of the blade 56, and to send a command signal to the pressure control unit 332 that is intended to increase the fluid pressure in the first chamber 312 when the setting instruction has the purpose of reducing the pitch of the blade 56.

[0258] The command module 335 is also configured to send a start-up instruction to the emergency circuit 334 (more specifically, to the auxiliary pump 338 of the emergency circuit) in the event of a failure of the pressure generator 330 .

[0259] The coupling system 278 couples the piston 310 to each blade 56 to convert a translation of the piston 310 along the longitudinal axis X and, where applicable, a rotation of the piston 310 about the longitudinal axis X into a rotation of each blade 56 about its pivot axis P.

[0260] To this end, the coupling system 278 includes a synchronizing ring 340 fixed to the piston 310 and a mechanism 342 for coupling the vane 56 with the synchronizing ring 340 for each of the vanes 56 .

[0261] The synchronizer ring 340 extends around the piston 310 in a radial plane.

[0262] Each coupling mechanism 342 includes a first hinge 344 fixed to the piston 310 , a second hinge 346 fixed to the blade 56 away from the pivot axis P of the blade 56 , and a rod 348 coupling the first hinge 344 to the second hinge 346 .

[0263] The first joint 344 is carried by the synchronizer ring 340. Here, the first joint is formed by a ball joint.

[0264] The second hinge 346 is also constituted by a ball joint. The second hinge is eccentric relative to the pivot axis P.

[0265] The rod 348 has a first end 350 hinged to the first hinge 344 and a second end 352 hinged to the second hinge 346. Advantageously, the rod 348 has an adjustable length, that is, the distance between the first end 350 and the second end 352 can be changed, which enables the control of the setting angle of each blade 56 to be precisely adjusted by the pitch change mechanism 70.

[0266] In the example shown, each coupling mechanism 342 also includes an eccentric member 354 connecting the fastening member 60 to the second hinge 346 .

[0267] The coupling system 278 is arranged so that the displacement of the piston 310 towards the stop 291 (i.e. towards the extended position of the piston) drives each blade 56 to rotate towards the flat position of the blade, and so that the displacement of the piston 310 away from the stop 291 (i.e. towards the retracted position of the piston) drives each blade 56 to rotate towards the feathered position of the blade. To this end, the second hinge 346 is arranged on the side of the trailing edge 57B relative to a plane Q that is orthogonal to the chord C and contains the pivot axis P, i.e. relative to the pivot axis P and the second hinge 146 at Figures 4 to 10 The positions occupied in the embodiments are relative.

[0268] Note that Fig.11In the example shown, the first hinge 344 is arranged upstream of the second hinge 346. The result of this is that, when the pitch change mechanism 70 is fixed, the natural stress on the blade 56 towards its flat position causes the coupling member 348 to work under compression, resulting in the risk of buckling of said coupling member 348. In order to avoid the risk of buckling of the coupling member 348 and to be able to use a lighter coupling member 348, a variant (not shown) in which the first hinge 344 is arranged downstream of the second hinge 346 will be preferred. This is because the particular arrangement of this variant (similar to that of the first embodiment) makes it possible for the natural stress of the blade 56 towards its flat position when the pitch change mechanism 70 is fixed to cause the coupling member 348 to work under traction rather than under compression.

[0269] The pitch changing mechanism 70 further comprises a pitch locking device 360 ​​adapted to lock the translation of the piston 310 relative to the frame 272 towards the extended position of the piston.

[0270] The locking device 360 ​​includes a support member 362 and a screw-nut system 364 .

[0271] The support member 362 can be in an operational position (eg, Fig.11 The device can be translated between an unlocked position (shown) and a locked position (not shown).

[0272] The support member 362 comprises a body 366 extending along the longitudinal axis X and centered on the longitudinal axis X. The body 366 has a first longitudinal end 368 (in particular an upstream longitudinal end), which is engaged by the hole 290 of the frame 272, and a free second longitudinal end 372. Moreover, in the example shown, the body 366 is hollow and open at its two longitudinal ends 368, 372.

[0273] The support member 362 also includes a skirt 374 secured to the body 366 and disposed about the second longitudinal end 372 of the body 366 .

[0274] The screw-nut system 364 includes a screw 376 and a nut 378 .

[0275] The screw 376 extends around the body 366 of the support member 362 and is coaxial with said body 366. The screw is fixed in translation to the support member 362 and is movably mounted to rotate relative to the support member 362 about the longitudinal axis X. To this end, the screw 376 is assembled on the support member 362 by means of a bearing 380. This bearing 380 is here inserted between the skirt 374 of the support member 362 and an end portion 382 of the screw 376, which is housed between the body 366 and the skirt 374.

[0276] The screw 376 has a second longitudinal end portion 384 opposite the end portion 382. The second longitudinal end portion 384 defines a radial stop portion 386. The stop surface 386 is located at a distance from the frame 272 when the support member 362 is in the operating position and bears against the stop portion 291 of the frame 272 when the support member 362 is in the locking position.

[0277] Here, the second longitudinal end portion 384 flares out from the threaded body 390 of the screw 376 up to the stop surface 386. As a result, the contact surface between the stop surface 386 and the stop portion 291 is increased, which increases the friction between the stop surface 386 and the stop portion 291 and enables better transmission of braking and locking forces.

[0278] Here, the stop surface 386 and the stop portion 291 are smooth. In a variant (not shown), the stop surface 386 and / or the stop portion 291 has a rough portion to further increase the friction between the stop surface 386 and the stop portion 291 and enable better force transmission.

[0279] The threaded body 390 extends from one of the end portions 382, ​​384 to the other end portion. The threaded body has external threads 392 on its outer periphery.

[0280] The nut 378 is fixed to the piston 310 and is coaxial with the screw 376. The nut interacts with the screw 376 so that translation of the nut 378 relative to the screw 376 along the longitudinal axis X drives the screw 376 to rotate about the longitudinal axis X relative to the support member 362.

[0281] The nut 378 has an internal thread 394 .

[0282] The screw-nut system 364 is in particular formed by a reversible planetary roller screw system 395. Typically, in addition to the screw 376 and the nut 378, this planetary roller screw system 395 comprises a plurality of rollers 396 arranged between the screw 376 and the nut 378, each roller 396 extending parallel to the longitudinal axis X.

[0283] Preferably, the description of the planetary roller screw system 195 given above applies mutatis mutandis to the planetary roller screw system 395 .

[0284] This feature enables good transmission of the force of the nut 378 to the screw 376 via the screw-nut system 364, while maintaining a small pitch in the helical coupling of the screw-nut system 364. In particular, in the case of rotational locking of the screw 376, this makes it possible to fix the nut 378 relative to the screw 376 even without a separate locking nut. Thus, the use of a separate locking nut can be omitted, which simplifies the manufacture of the mechanism and reduces costs, while increasing the reliability of the mechanism and minimizing the mass of the mechanism.

[0285] The locking device 360 ​​further includes a biasing device 420 that biases the support member 362 into the locked position of the support member and a retaining device 422 that is used to retain the support member 362 in the operating position of the support member when the pitch changing mechanism 70 is in normal operating conditions.

[0286] The biasing device 420 is here constituted by a compression spring which is compressed between the frame 272 and a shoulder 424 fixed to the support member 362 .

[0287] The retaining device 422 includes a balancing actuator 430 including a balancing piston 432 and a balancing chamber 434 .

[0288] The balancing piston 432 is fixed to the support member 362 . The balancing piston is movably mounted in translation relative to the frame 272 along the longitudinal axis X. The balancing piston is in particular coaxial with the support member 362 . In the example shown, the balancing piston is arranged in the longitudinal extension of the support member 362 .

[0289] The balance piston 432 and the frame 272 together define a chamber 434 .

[0290] The balancing chamber 434 is fluidically connected to the pressure generator 330 via a fluid connection circuit 436, so as to supply the actuating fluid at the third pressure. The balancing chamber is intended to counteract the bias of the biasing device 420 when this supply is active.

[0291] To this end, the balancing actuator 430 is arranged so that the pressure exerted on the piston 432 by the fluid contained in the chamber 434 is directed in a direction opposite to the biasing direction of the biasing device 420: in the example shown, the balancing piston 432 is arranged between the chamber 434 and the shoulder 424, and the shoulder 424 is arranged between the piston 432 and the biasing device 420. In addition, the balancing piston 432 and the balancing chamber 434 are dimensioned so that when the chamber 434 is supplied with an actuating fluid at a third pressure, the force exerted on the piston 432 by the actuating fluid is greater than the biasing of the biasing device 420.

[0292] Thus, when the actuating fluid at the third pressure is supplied to the chamber 434, the bias of the biasing device 420 is removed and the support member 362 remains in the operative position.

[0293] In the example shown, the pressure control unit 332 is fluidly arranged between the pressure generator 330 and the fluid connection circuit 436. The pressure control unit has a first configuration in which the pressure control unit isolates the fluid connection circuit 436 from the return line 336 and a second configuration in which the pressure control unit fluidly connects the fluid connection circuit 436 to the return line 336.

[0294] The pressure control unit 332 is configured to be normally in a first configuration of the pressure control unit, and to switch to a second configuration of the pressure control unit upon receiving a command instruction sent by the command module 335 .

[0295] Still refer to Fig.11 , the pitch changing mechanism 70 finally comprises a fluid transfer bearing 457 intended to supply the control actuator 274 with actuating fluid coming from the control system 276 .

[0296] To this end, fluid transfer bearing 457 is configured to transfer actuating fluid from a fixed reference frame attached to nacelle 20 to a rotating reference frame attached to fan rotor 54 , and more specifically to first chamber 312 and second chamber 314 of control actuator 274 .

[0297] For this purpose, refer to Fig.12 The fluid transfer bearing 457 includes a stator 458 and a rotor 459, the stator being fixed relative to the nacelle 20 and the rotor being movably engaged with the fan rotor 54 (and therefore with the control actuator 274) about the longitudinal axis X relative to the stator 458. The fluid transfer bearing also includes a first circuit 460 and a second circuit 461, the first circuit being fluidly connected to the first fluid chamber 312 to supply the actuating fluid supplied by the control system 276 to the first fluid chamber 312, and the second circuit being fluidly connected to the second fluid chamber 314 to supply the actuating fluid supplied by the control system 76 to the second fluid chamber 114.

[0298] The stator 458 has the shape of a cylinder of revolution coaxial with the longitudinal axis X. The stator is coupled by its downstream end 462 to the structure (not shown) of the nacelle 20 .

[0299] The rotor 459 is in the shape of a cylinder of revolution coaxial with the longitudinal axis X. The rotor extends around the stator 458. The outer periphery of the rotor is in contact with the frame 272. The rotor is rotationally guided relative to the stator 458 about the axis X by means of a bearing 464 arranged between the rotor 459 and the stator 458.

[0300] Therefore, the fluid transfer bearing 457 is coaxial with the axis X. Therefore, the fluid transfer bearing is also coaxial with the control actuator 274.

[0301] The first circuit 460 includes: a first axial channel 465A, which is formed in the stator 458; a plurality of first radial apertures 465B (only one of the plurality of first radial apertures is shown here), which are formed in the stator 458 and connect the axial channel 465A to the outer periphery of the stator 458; a first circumferential groove 465C, which is formed between the rotor 459 and the stator 458 and each radial aperture 465B leads to the first circumferential groove; and a plurality of first radial channels 465D, which are formed in the rotor 459 and extend substantially from the groove 465C to a first supply passage 466 of the first fluid chamber 112 formed between the frame 72 and the rotor 459.

[0302] The first axial channel 465A has an axial direction parallel to the axis X. In the example shown, the first axial channel is in particular straight and coaxial with the axis X. In a variant (not shown), the first axial channel 465A is curved and / or also has a radial extension in a direction orthogonal to the axis X.

[0303] Furthermore, in the example shown, the first axial channel 465A has an annular radial cross-section, ie the first axial channel is solid at its center.

[0304] Each first radial orifice 465B has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each first radial orifice 465B is straight in particular along the radial direction. In a variant (not shown), at least one first radial orifice 465B is curved and / or also has an axial extension parallel to the axis X.

[0305] The first circumferential groove 465C extends parallel to a radial plane orthogonal to the axis X.

[0306] Each first radial channel 465D has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each first radial channel 465D is straight in particular along the radial direction. In a variant (not shown), at least one first radial channel 465D is curved and also has an axial extension parallel to the axis X and / or a circumferential extension along a direction orthogonal to the axis X and the radial direction.

[0307] The first supply passage 466 extends from the outlet of the first radial channel 465D as far as the inlet of the first fluid chamber 312. In the example shown, the first supply passage is substantially straight and extends substantially parallel to the axis X.

[0308] The second circuit 461 includes: a second axial channel 467A, which is formed in the stator 458; a plurality of second radial orifices 467B (only one of the plurality of second radial orifices is shown here), which are formed in the stator 458 and connect the axial channel 467A to the outer periphery of the stator 458; a second circumferential groove 467C, which is formed between the rotor 459 and the stator 458 and each radial orifice 467B leads to the second circumferential groove; and a plurality of second radial channels 467D, which are formed in the rotor 459 and extend radially from the groove 467C to a second supply passage 468 of the second fluid chamber 114 formed between the frame 72 and the rotor 459.

[0309] The second axial channel 467A has an axial extension parallel to the axis X. Advantageously, the second axial channel is coaxial with the first axial channel 465A. In the example shown, the second axial channel is in particular straight and coaxial with the axis X. In a variant (not shown), the second axial channel 467A is curved and / or also has a radial extension along a direction orthogonal to the axis X.

[0310] Furthermore, in the example shown, the second axial channel 467A has an annular radial cross section, ie the second axial channel is solid at its center.Here, the second axial channel extends around the first axial channel 465A.

[0311] Each second radial orifice 467B has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each second radial orifice 467B is straight in particular along the radial direction. In a variant (not shown), at least one second radial orifice 467B is curved and / or also has an axial extension parallel to the axis X.

[0312] Each second radial orifice 467B is here arranged axially downstream of a first radial orifice 465B.

[0313] The second circumferential groove 467C extends parallel to a radial plane orthogonal to the axis X. Here, the second circumferential groove is arranged axially downstream of the first circumferential groove 465C.

[0314] Each second radial channel 467D has a radial extension along a radial direction orthogonal to the axis X. In the example shown, each second radial channel 467D is straight in particular along the radial direction. In a variant (not shown), at least one second radial channel 467D is curved and also has an axial extension parallel to the axis X and / or a circumferential extension along a direction orthogonal to the axis X and the radial direction.

[0315] Each second radial channel 467D is here arranged axially downstream of a first radial channel 465D.

[0316] The second supply passage 468 extends from the outlet of the second radial channel 466D as far as the inlet of the second fluid chamber 314. In the example shown, the second supply passage is substantially straight and extends substantially parallel to the axis X.

[0317] The first circuit 460 and the second circuit 461 are independent circuits, ie, the first circuit and the second circuit are not in fluid communication with each other.

[0318] return Fig.11 The outer diameter of the guide bearing 457 is smaller than the inner diameter of the guide bearing 53 of the fan rotor 54. The guide bearing 457 is arranged upstream of the reduction gear and is specifically accommodated in the accommodation portion 304 defined by the central cylindrical body 294.

[0319] Therefore, the guide bearing 457 is at least partially surrounded by the control actuator 274. In particular, the control actuator 274 extends around more than half of the fluid conveying bearing 457 (advantageously around more than three quarters of the fluid conveying bearing) along the axis X. In order to achieve this measurement, the axial ends of the control actuator 274 and the axial ends of the guide bearing 457 are considered, which are defined as follows:

[0320] - for the control actuator 274 , the axial ends of the control actuator are constituted by the ends 288 , 302 of the fluid chambers 312 , 314 ;

[0321] - For the guide bearing 457, the axial end of the guide bearing is constituted by the following limit: beyond the limit, the rotor 459 and the stator 458 no longer coexist (that is, starting from the guide bearing, the first axial end of the rotor 459 or the first axial end of the stator 458 encountered defines the axial end of the guide bearing 457).

[0322] In particular, in the example shown, the control actuator 274 extends along the axis X around the entire fluid transport bearing 457 .

[0323] Unlike the fluid delivery bearing 257, the fluid delivery bearing 457 is not configured here to supply the balanced actuator 430 with actuating fluid from the control system 276. Instead, the stator 458 is axially drilled at its center and is traversed by a central channel 470 intended to supply the balanced actuator 430.

[0324] The central channel 470 is here straight and colinear with the longitudinal axis X. The central channel extends through the fluid delivery bearing 257 , but also through the support member 362 and the balancing piston 432 as far as the balancing chamber 434 .

[0325] Typically, the central passage 470 is fixed in the reference frame of the nacelle 20 . In a variant, the central passage is fixed in the rotating reference frame of the fan rotor 54 .

[0326] A seal is formed at the periphery of the central passage 470 between the central passage 470 and the balancing piston 432. Advantageously, a second seal is also formed at the periphery of the central passage 470 between the central passage 470 and the upstream end 298 of the central cylinder 294, the central passage 470 passing through the upstream end of the central cylinder at the center of the upstream end of the central cylinder.

[0327] A method for changing the pitch of the blades 56 implemented by the pitch changing mechanism 70 according to the second embodiment will now be described.

[0328] In a first step of the method, the command module 335 first receives a setting instruction aimed at increasing the pitch of the blade 56. Then, the command module 335 sends a command signal to the pressure control unit 332 aimed at increasing the fluid pressure in the first chamber 312. Due to the increase in the fluid pressure in the first chamber 312, the control piston 310 is displaced toward its retracted position, which drives the blade 56 to pivot toward a large pitch (i.e., toward the feathered position) through the coupling system 278.

[0329] Once the piston 310 reaches its equilibrium position, the piston stabilizes and the vanes 56 maintain a fixed orientation.

[0330] In the second step of the pitch change method, the command module 335 first receives a setting instruction aimed at reducing the pitch of the blade 56. Then, the command module 335 sends a command signal to the pressure control unit 332 aimed at increasing the fluid pressure in the second chamber 314. Due to the increase in the fluid pressure in the second chamber 314, the control piston 310 is displaced toward its extended position, which drives the blade 56 to pivot toward the small pitch (i.e., toward the flat position) through the coupling system 278.

[0331] Once the piston 310 reaches the equilibrium position, the piston stabilizes and the vanes 56 maintain a fixed orientation.

[0332] Optionally, the pitch changing method further comprises, after the first step or the second step, a step of commandably locking the orientation of the blade 56 .

[0333] During this step, the command module 335 sends a pitch lock command to the pressure control unit 332. Under the effect of this command, the pressure control unit 332 fluidically connects the fluid connection circuit 436 to the return line 336, causing a drop in the fluid pressure in the balancing chamber 434. As a result, the fluid pressure in said chamber 434 is insufficient to counteract the bias of the biasing device 420, which therefore drives the support member 362 to shift to its locked position.

[0334] During this displacement, the screw 376 rotates around the longitudinal axis X under the action of the resistance exerted by the assembly of the nut 378 and the roller 394 (the assembly of the nut and the roller is kept from translational movement by the control actuator 274) until the stop surface 386 of the screw bears against the stop portion 291 of the frame 272, thereby locking the rotation of the screw 376 around the longitudinal axis X and the translation of the screw along the same axis X.

[0335] Thus, even in the event of a loss of fluid pressure in the first chamber 312 , the vanes 56 are locked in the orientation of the vanes.

[0336] In the event of a loss of fluid pressure only in the second chamber 314, the piston 310 is displaced towards its retracted position under the effect of the pressure difference between the two chambers 312, 314, thereby driving the screw 376 and the support member 362 by this displacement, the support member finding its operating position. The piston 310 is therefore no longer fixed and can continue to be displaced towards its retracted position until the blades 56 are back in the feathered position.

[0337] In the event of a failure of the control system 276 (typically, in the event of a failure of the pressure generator 330 ), the pitch variation method includes an additional step of non-commanded locking of the orientation of the blades 56 .

[0338] During this step, a failure of the control system 276 causes the fluid pressure in the balancing chamber 434 to drop, typically because the pressure generator 330 is no longer able to bring the actuating fluid to the third pressure. As a result, the fluid pressure in the chamber 434 is insufficient to offset the bias of the biasing device 420, which drives the support member 362 to shift to its locked position.

[0339] During this displacement, the screw 376 drives the nut 378 and the roller 394 by this displacement, which no longer remain non-translationally moved due to the loss of power controlling the actuator 274. The blade 56 thus pivots slightly towards the small pitch until the stop surface 386 of the screw 376 bears against the stop 291 of the frame 272, thereby locking the screw 376 in rotation about the longitudinal axis X and in translation along the same axis X.

[0340] The blade 56 is thus prevented from pivoting towards a low pitch by the locking device 360 ​​.

[0341] The non-commanded locking step is followed by a safety protection step of the fan 50. During this step, the emergency circuit 334 is activated and supplies actuating fluid to the first fluid chamber 312 to increase the fluid pressure in this chamber. Under the effect of this pressure increase, the piston 310 is displaced towards its retracted position, thereby driving the screw 376 and the support member 362 by this displacement, which returns to its operating position. Therefore, the piston 310 is no longer fixed and can continue to be displaced downstream until the blades 45 return to the feathered position.

[0342] Note that these different steps can be performed independently of each other.

[0343] Thus, with the exemplary embodiment described above, since the fluid delivery bearing 257, 457 is carefully positioned within the cavity surrounded by the control actuator 74, 274, the fluid delivery bearing is arranged upstream of the reduction gear, so that the fluid delivery bearing 257, 457 can be easily accessed without sacrificing the length of the turbine 12. In addition, the volume of the fluid delivery bearing 257, 457 itself is minimized.

[0344] These exemplary embodiments also make it possible to dispense with the use of a locking nut different from the nut 178, 378 of the screw-nut system 164, 364. This results in simplified manufacturing, reduced costs and increased reliability of the locking device 160, 360 and, therefore, of the pitch change mechanism 70.

[0345] Furthermore, due to the compactness of the control actuator 74 and the use of a less resistant and therefore lighter coupling member 148, Figures 3 to 9 The exemplary embodiment of makes it possible to simplify the pitch changing mechanism 70 .

[0346] Figures 3 to 9 The described exemplary embodiment of makes it possible to omit the use of a support arranged upstream of the locking device 160 , which facilitates access to the pitch change mechanism 70 , in particular the coupling system 78 , after the pitch change mechanism has been assembled.

[0347] Figures 3 to 9 These exemplary embodiments ultimately enable a highly precise control of the setting angle of the blades 56 , which enables blades 56 having large sizes and complex geometries to be mounted closely spaced on the hub 55 , thereby enabling increased efficiency of the turbine 12 .

Claims

1. A pitch changing mechanism (70) for adjusting the angular position of at least one variably settable blade (56) about a pivot axis (P) of the blade (56), the pitch changing mechanism (70) comprising: - a frame (72, 272) fixed relative to said pivot axis (P), a control actuator (74, 274) comprising a fixed part (100, 308) fixed to the frame (72, 272) and a movable part (102, 309) movable in translation relative to the fixed part (100, 308) along a longitudinal axis (X) between a retracted position and an extended position, a coupling system (78, 278) coupling the movable part (102, 309) to the variable setting blade (56) for converting a translation of the movable part (102, 309) along the longitudinal axis (X) into a rotation of the variable setting blade (56) about the pivot axis (P), and a fluid conveying bearing (257, 457) for supplying an actuating fluid from a source (76, 276) to the control actuator (74, 274), the control actuator (74, 274) being rotationally movable relative to the source about the longitudinal axis (X), Wherein the control actuator (74, 274) extends at least partially around the fluid delivery bearing (257, 457).

2. The pitch changing mechanism (70) according to claim 1, wherein: The control actuator (74, 274) is coaxial with the fluid transfer bearing (257, 457).

3. The pitch changing mechanism (70) according to claim 1 or 2, wherein: The control actuator (74, 274) extends around more than half of the fluid transfer bearing (257, 457), advantageously around more than three quarters of the fluid transfer bearing.

4. The pitch changing mechanism (70) according to any one of the preceding claims, comprising a pitch locking device (160) adapted to lock the translation of the movable part (102) relative to the fixed part (100) in at least one direction, the pitch locking device (160) comprising: a locking member (162) movable in translation relative to the frame (72) along the longitudinal axis (X) between an operating position and a locking position, - biasing means (240) biasing the locking member (162) towards its locked position, and - a retaining device (242) for retaining the locking member (162) in its operating position under normal operating conditions, the retaining device (242) comprising a balancing actuator (250) comprising a balancing chamber (254) supplied with an actuating fluid to counteract the bias of the biasing device (240), The fluid transfer bearing (257) is configured to supply the balancing actuator (250) with actuating fluid from the source (76).

5. A pitch changing mechanism (70) according to any one of the preceding claims, wherein: The fluid transport bearing (257, 457) includes a stator (258, 458) and a rotor (259, 459), the rotor being movably engaged with the control actuator (74, 274) relative to the stator (258, 458) about the longitudinal axis (X), the rotor (259, 459) extending around the stator (258, 458).

6. The pitch changing mechanism (70) according to claim 5, wherein: The fluid transport bearing (257, 457) comprises a plurality of circuits (260, 261, 269, 460, 461) that are independent of each other, at least one of the circuits (260, 261, 269, 460, 461) comprising: - an axial channel (265A, 267A, 270A, 465A, 466A) formed in the stator (258, 458), - at least one radial aperture (265B, 267B, 270B, 465B, 466B) formed in the stator (258, 458) and coupling the axial channel (265A, 267A, 270A, 465A, 466A) to the outer periphery of the stator (258, 458), a circumferential groove (265C, 267C, 270C, 465C, 466C) formed between the rotor (259, 459) and the stator (258, 458) and into which the or each radial aperture (265B, 267B, 270B, 465B, 466B) opens, and - at least one radial channel (265D, 267D, 270D, 465D, 466D) formed in the rotor (259, 459) and extending radially from the recess (265C, 267C, 270C, 465C, 466C) to a supply passage (266, 268, 271, 466, 468) formed in the frame (72, 272) or between the frame (72, 272) and the fluid transport bearing (257, 457).

7. The pitch changing mechanism (70) according to claim 6, wherein: The axial channels (265A, 267A, 270A, 465A, 466A) of the different circuits (260, 261, 269, 460, 461) are coaxial.

8. A pitch changing mechanism (70) according to any one of the preceding claims, wherein: The control actuator (74, 274) includes a first fluid chamber (112, 312) and a second fluid chamber (114, 314), each of which contains an actuating fluid for actuating displacement of the movable part (102, 309) relative to the fixed part (100, 308), and the fluid transport bearing (257, 457) includes a first circuit (260, 460) and a second circuit (261, 461), the first circuit being fluidically connected to the first fluid chamber (112, 312) to supply the actuating fluid provided by the source (76, 276) to the first fluid chamber (112, 312), and the second circuit being fluidically connected to the second fluid chamber (114, 314) to supply the actuating fluid provided by the source (76, 276) to the second fluid chamber (114, 314).

9. A fan rotor (54) for a turbine, the fan rotor comprising a hub (55) and a plurality of variable-set blades (56), each variable-set blade being pivotable relative to the hub (55) about a corresponding pivot axis (P), the rotor (54) further comprising a pitch changing mechanism (70) according to any one of the preceding claims, the pitch changing mechanism being used to adjust the angular position of each of the variable-set blades (56) about its corresponding pivot axis (P).

10. The fan rotor (54) according to claim 9, comprising a guide bearing (53) for guiding the fan rotor (54) in rotation relative to the turbine nacelle (20) about the longitudinal axis (X), the inner diameter of the guide bearing (53) being greater than the outer diameter of the fluid transport bearing (257, 457).

11. The fan rotor (54) according to claim 9 or 10, wherein: The longitudinal axis (X) constitutes the axis of rotation of the fan rotor (54).

12. A turbomachine (12) comprising a fan rotor (54) according to any one of claims 9 to 11.

13. The turbine (12) according to claim 12, wherein: The longitudinal axis (X) constitutes the axis of elongation of the turbine (12).

14. An aircraft (10) comprising at least one turbine (12) according to claim 12 or 13.

15. A method for changing the pitch of blades (56) of a fan rotor (54) of a turbine, each blade being pivotable about a respective pivot axis (P) relative to a hub (55) of the fan rotor (54), the method comprising adjusting the angular position of each of the blades (56) about its respective pivot axis (P) by means of a pitch changing mechanism (70) according to any one of claims 1 to 8.

16. The method according to claim 15, comprising the additional step of locking the orientation of the blade (56) by means of the pitch lock device (160).

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