Hydraulic actuation circuit for adjusting the pitch of blades

Abstract

The invention relates to an actuation system (1) for adjusting the pitch of blades of an aircraft engine fan (200) comprising a hydraulic cylinder (5), comprising an isolation valve (71) capable of selectively adopting a first configuration and a second configuration, such that: - when the isolation valve (71) is in the first configuration, the hydraulic cylinder (5) is configured such that its position is controlled by a control fluid coming from a main hydraulic circuit (4a); and - when the isolation valve (71) is in the second configuration, the piston of the hydraulic cylinder (5) can move in a first direction of movement under the action of a control fluid of an auxiliary hydraulic circuit (4b), the fan blade being oriented into a high pitch position, and the auxiliary hydraulic circuit (4b) not being hydraulically connected to the main hydraulic circuit (4a).

Description

[0001] DESCRIPTION

[0002] TITLE: HYDRAULIC CIRCUIT FOR AGAINST VANES PITCH ADJUSTMENT

[0003] TECHNICAL FIELD

[0004] This disclosure relates to the general field of aircraft engines, and in particular to the blade pitch control actuation system of an aircraft engine fan.

[0005] STATE OF THE ART

[0006] Climate change is a major concern, and there is an urgent need to reduce carbon emissions globally. Ambitious standards have been adopted to restrict emissions from civil aviation. Technological research efforts have thus led to very significant improvements in aircraft energy efficiency.

[0007] These efforts focus on new generations of aircraft engines, the reduction of aircraft weight, particularly through the materials used and lighter onboard equipment, and the development of the use of electric technologies to provide propulsion.

[0008] Improving existing systems is also necessary. Optimizing the fan blade pitch of the engine is a key factor in improving aircraft performance. By dynamically adjusting the fan blade orientation using an actuation system, it is possible to maximize propulsion during different flight phases, such as takeoff, cruise, and landing. This dynamic adaptation not only helps reduce fuel consumption but also improves the management of mechanical stresses on the engine, thus extending its lifespan. This helps meet the growing demands of the aerospace industry in terms of environmental performance and sustainability.

[0009] The actuation system typically includes at least one hydraulic cylinder whose position is controlled by a primary control system. The hydraulic cylinder plays a crucial role in providing the force necessary to make precise and rapid blade orientation adjustments, essential for the safety and efficiency of aerial operations.

[0010] In the event of a loss of the hydraulic cylinder's ability to control the blade position, a malfunction of the main control system, or a failure of another engine component necessitating engine shutdown, it is necessary to return the blades to the "feathered" position, i.e., parallel to the airflow, in order to minimize the drag created by the fan when stationary. Aerodynamic forces acting on the blades tend, conversely, to return them to the opposite position.

[0011] Typically, the feathering function can be performed by an auxiliary pilot system also connected to the hydraulic cylinder. Typically, the auxiliary pilot system includes a motor-pump unit and an auxiliary hydraulic circuit in the fixed frame, while the hydraulic cylinder is in the rotating frame.

[0012] However, connecting this auxiliary actuation system to the same hydraulic cylinder as the main actuation system creates shared hydraulic connections between the main and auxiliary circuits. Failure of certain components in the main and auxiliary circuits, particularly pipe ruptures, can lead to the loss of both hydraulic circuits or unintentional hydraulic connections, rendering the cylinder position control by the main system and the feathering function of the auxiliary system inoperative.

[0013] DESCRIPTION OF THE INVENTION

[0014] One purpose of this disclosure is to propose an actuation system to connect the two main and auxiliary hydraulic circuits to the same hydraulic cylinder while minimizing their common failure modes in order to improve the availability of the blower blade flagging function by the auxiliary system in case of failure of the main actuation system and to improve the availability of the hydraulic cylinder position control function by the main actuation system in case of failure of the auxiliary system.

[0015] This goal is achieved by an aircraft engine fan blade pitch actuation system comprising a hydraulic cylinder, the hydraulic cylinder comprising a cylinder and a piston, the piston delimiting within the cylinder a retraction chamber and an extension chamber, each of the retraction chamber and the extension chamber being suitable for being supplied with a control fluid, so as to cause a displacement of the piston relative to the cylinder in a first direction of movement when a pressure of the control fluid in the extension chamber is greater than a pressure of the control fluid in the retraction chamber and to cause a displacement of the piston relative to the cylinder in a second direction of movement, opposite to the first direction of movement, when a pressure of the control fluid in the retraction chamber is greater than a pressure of the control fluid in the extension chamber;the actuation system further comprising;

[0016] - a main hydraulic circuit;

[0017] - an auxiliary hydraulic circuit;

[0018] - a rotary hydraulic distributor comprising a movable, rotatable part configured to be driven in rotation by the blower, the hydraulic distributor comprising

[0019] - an isolation valve capable of selectively adopting a first and a second configuration, the isolation valve comprising an actuating element configured to control the configuration of the isolation valve, and

[0020] - a first supply port and a second supply port, each connected to the main hydraulic circuit;

[0021] - an expansion port connected to the expansion chamber;

[0022] - a retraction port connected to the retraction chamber;

[0023] - a return port connected to the auxiliary hydraulic circuit;

[0024] - an auxiliary supply line connected to the auxiliary hydraulic circuit, comprising an actuation line connecting the auxiliary hydraulic circuit to the actuating member of the isolation valve, and an auxiliary extension line connecting the auxiliary hydraulic circuit to the extension chamber via a check valve configured to prevent circulation of the control fluid from the extension chamber to the auxiliary hydraulic circuit; so that

[0025] - when the isolation valve is in the first configuration, the first supply port is hydraulically connected to the extension port and the second supply port is hydraulically connected to the retraction port, the return port being isolated, so that the hydraulic cylinder is configured to be position-controlled by a control fluid from the main hydraulic circuit; and

[0026] - when the isolation valve is in the second configuration, the return port is hydraulically connected to the retraction port, the extension port, the first supply port and the second supply port being isolated, so that the hydraulic cylinder piston can move in the first direction of travel by action of a control fluid from the auxiliary hydraulic circuit, the blower blade orienting itself towards a large pitch position, and the auxiliary hydraulic circuit not being hydraulically connected with the main hydraulic circuit.

[0027] This actuation system isolates the auxiliary hydraulic circuit from the main hydraulic circuit, thereby reducing common failure modes. In normal operation, when the isolation valve is in its first configuration, the hydraulic cylinder is connected to the main hydraulic circuit, allowing for precise and fine actuation. The isolation of the return port and the presence of the check valve further isolate the two hydraulic circuits, ensuring that even in the event of an external leak in the auxiliary hydraulic circuit (for example, caused by a pipe rupture), the hydraulic cylinder can still be actuated by the main hydraulic circuit.

[0028] Similarly, when an external leak occurs on the main hydraulic circuit, the auxiliary hydraulic circuit can control the isolation valve in the second position, thus isolating the faulty main hydraulic circuit and allowing the hydraulic cylinder piston to move in the first direction of travel, in order to reach a first position of the hydraulic cylinder corresponding, for example, to a flagging position of the blower blades.

[0029] The invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations:

[0030] - the actuation device being configured to operate the isolation valve in the second configuration when a pressure in the auxiliary supply path is greater than a threshold pressure value, the isolation valve being maintained in the first configuration otherwise;

[0031] - the actuation system further includes an auxiliary pilot system configured to control a circulation of the control fluid in the auxiliary hydraulic circuit;

[0032] - the actuation system further includes an auxiliary control unit, and the auxiliary piloting system includes an auxiliary electric motor and an auxiliary hydraulic pump, the auxiliary electric motor being configured to drive the auxiliary hydraulic pump in rotation, and the auxiliary control unit being configured to pilot the auxiliary electric motor so as to modify the pressure of the auxiliary supply path, corresponding to an extension line of the hydraulic cylinder so that it can reach a position for feathering the blades;

[0033] - the auxiliary hydraulic circuit includes a feathering valve connected to the auxiliary supply line, and a solenoid valve configured to actuate the feathering valve so as to change the pressure of the auxiliary supply line;

[0034] - the feathering valve is actuated between a passing position in which the isolation valve is in the second configuration, and a blocking position in which the auxiliary hydraulic circuit is isolated from the isolation valve;

[0035] - the auxiliary hydraulic circuit is arranged in the hydraulic distributor so that the feathering valve and the solenoid valve are configured to be driven in rotation by the blower; - the main hydraulic circuit includes a safety hydraulic circuit comprising at least two check valves and one of the following: two check valves and one pressure relief valve, and at least two pressure relief valves.

[0036] - the actuation system further includes a main pilot system configured to pilot a circulation of the control fluid in the main hydraulic circuit, and in which the main hydraulic circuit includes a distribution valve suitable for selectively adopting an active position and a passive position, so that, when the distribution valve is in the active position, the hydraulic cylinder is configured to be servo-controlled in position by the main pilot system, and when the distribution valve is in the passive position, the control fluid can only flow from the retraction chamber to the extension chamber.

[0037] According to another aspect of the invention, an aircraft engine is proposed comprising a fan and a pitch control actuation system as described above, the fan being mounted movable in rotation about a longitudinal axis, and comprising a plurality of blades, each blade extending along its own radial axis, so that, when the isolation valve is in the second configuration, each blade is configured to be actuated in rotation about its own radial axis by the actuation system so as to orient itself parallel to the longitudinal axis towards the high pitch position.

[0038] DESCRIPTION OF THE FIGURES

[0039] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0040] Figure 1 is a top view of an aircraft according to an example of an embodiment of the invention.

[0041] Figure 2 is a simplified partial longitudinal cross-sectional view of an aircraft gas turbine engine.

[0042] Figure 3 is a schematic representation of a gas turbine engine pitch change mechanism illustrated in a general setting.

[0043] Figure 4 is a schematic representation of a system for actuation of the pitch adjustment of the blades of the gas turbine engine illustrated in a first embodiment.

[0044] Figure 5 is a detailed hydraulic diagram of the actuation system.

[0045] Figure 6 is a detailed hydraulic diagram of the rotary hydraulic distributor in the previous embodiment, in a first position of the isolation valve. Figure 7 is a detailed hydraulic diagram of the rotary hydraulic distributor in the previous embodiment, in a second position of the isolation valve.

[0046] Figure 8 is a schematic representation of a blade actuation system for the gas turbine engine illustrated in a second embodiment.

[0047] Figure 9 is a detailed hydraulic diagram of the actuation system.

[0048] Figure 10 is a detailed hydraulic diagram of the rotary hydraulic distributor in the previous embodiment.

[0049] Across all figures, similar elements bear identical references.

[0050] DETAILED DESCRIPTION OF THE INVENTION

[0051] Aircraft 100 shown in Figure 1 includes gas turbine engines 110 for propulsion.

[0052] In the example shown, aircraft 100 is an airplane. It conventionally comprises a fuselage 114, a tail assembly 116, and two wings 118. The gas turbine engines 110 are two in number and are each housed under a respective wing 118. This disclosure extends more generally to other types of aircraft and propulsion systems; for example, the gas turbine engines 110 could be arranged along the fuselage 114, near the tail assembly 116, or aircraft 100 could comprise one or at least three gas turbine engines 110.

[0053] One of the gas turbine engines 110 is shown in Figure 2.

[0054] As can be seen in this figure, the gas turbine engine 110 is elongated along a longitudinal axis X. It typically exhibits angular symmetry around said longitudinal axis X, that is to say, there is at least one angle for which the gas turbine engine 110 is invariant under rotation around the longitudinal axis X.

[0055] Subsequently, the terms "interior" and "exterior", "internal" and "external", as well as their variations, are understood in reference to the X axis, an element described as "interior" or "internal" being oriented towards the X axis while an "exterior" or "external" element is oriented in the opposite direction to the X axis.

[0056] The gas turbine engine 110 conventionally comprises a casing 120, an internal channel 122 for the circulation of a gas flow through the casing 120, a combustion chamber 124 housed in the channel 122, a powerhead 126 and an exhaust nozzle 128. In the following, the terms "upstream" and "downstream" are understood to refer to the direction of flow of a gas stream through the channel 122.

[0057] The engine body 126 comprises a compressor 130, a turbine 132, and a drive shaft 134 coupling the turbine 132 to the compressor 130 for driving the compressor 130 by the turbine 132. The compressor 130 is located upstream of the combustion chamber 124 and supplies the combustion chamber 124 with compressed air. The turbine 132 is located downstream of the combustion chamber 124 and receives the exhaust gases exiting the combustion chamber 124.

[0058] The transmission shaft 134 has the longitudinal axis X as its axis of rotation. The transmission shaft 134 is guided in rotation relative to the housing 120 by means of bearings.

[0059] In the example shown, the turbomachine 110 is a multi-body turbomachine, in particular a double body, comprising a low-pressure body 140 in addition to the engine body 126. The engine body 126 then constitutes a high-pressure body, the compressor 130 being a high-pressure compressor, the turbine 132 being a high-pressure turbine and the drive shaft 134 being a high-pressure shaft.

[0060] The low pressure body 140 includes a low pressure compressor 142, a low pressure turbine 144 and a low pressure shaft 146 coupling the low pressure turbine 144 to the low pressure compressor 142 for driving the low pressure compressor 142 by the low pressure turbine 144.

[0061] The low-pressure compressor 142 is located upstream of the high-pressure compressor 130 and supplies the latter with compressed air. The low-pressure turbine 144 is located downstream of the high-pressure turbine 132 and receives the exhaust gases exiting the latter.

[0062] The low-pressure shaft 146 is guided in rotation relative to the housing 120 by means of bearings. The low-pressure shaft 146 is coaxial with the high-pressure shaft 134. Therefore, its axis of rotation is also the longitudinal axis X. In particular, the low-pressure shaft 146 extends inside the high-pressure shaft 134.

[0063] The turbomachine 110 also includes a blower 200 to drive the gas flow into an external circulation channel 152 surrounding the casing 120. A primary gas flow A (hot), consisting of the portion of the gas flow driven into the internal circulation channel 122, is thus distinguished from a secondary gas flow B (cold), consisting of the portion of the gas flow driven into the external circulation channel 152.

[0064] The blower 200 comprises a blower rotor 240. This blower rotor 240 is rotatably mounted relative to the housing 120 about the longitudinal axis X by means of a guide bearing. It includes a hub 250 provided with blower blades 20 extending substantially radially outwards from the hub 250. These blades 20, when rotated, drive the gas flow into the external circulation channel 152.

[0065] Each 20-bladed wing comprises, in a known manner, a leading edge, a trailing edge and a cord connecting the leading edge to the trailing edge.

[0066] The blower rotor 240 is driven in rotation by the low-pressure turbine 144, via the low-pressure shaft 146. Preferably, this drive is achieved via a reduction gear allowing the blower rotor 240 to rotate at a speed lower than that of the low-pressure shaft 146. In an embodiment not shown, the drive is direct, i.e. the blower rotor 240 is fixed in rotation to the low-pressure shaft 146.

[0067] In the example shown, the blower 200 also includes a blower stator 158 comprising fixed blades 159 arranged at the periphery of the housing 120, in the external circulation vein 152, along a plane orthogonal to the longitudinal axis X. This blower stator 158 is arranged here downstream of the blower rotor 240. In an alternative embodiment, the blower 200 may include, instead of the blower stator 158, a counter-rotating blower rotor.

[0068] Advantageously, the fan 200 is, as shown, unshod, meaning that the external circulation channel 152 has no peripheral delimitation. The turbomachine 110 then consists, as shown, of a turbojet with an unshod fan or, alternatively, a turboprop. Alternatively, the external circulation channel 152 is defined between the casing 120 and a nacelle surrounding the fan 200. The turbomachine 110 is then typically a turbojet with a high bypass ratio, the bypass ratio being defined as the ratio of the secondary flow rate B (cold) to the primary flow rate A (hot).

[0069] In the example shown, the gas turbine engine 110 is specifically of the "puller" type, meaning that the fan 200 is positioned upstream of the internal circulation channel 122 and also drives the gas flow within it. Alternatively, the gas turbine engine 110 can be of the "pusher" type, meaning that the fan 200 is located around the downstream half of the casing 120.

[0070] The blades 20 of the fan rotor 240 have variable pitch, meaning that each blade 20 is mounted to pivot relative to the hub 250 around its own pivot axis P. This pivot axis P extends along the direction of elongation of the blade 20. It is orthogonal to the longitudinal axis X. Each blade 20 is specifically able to pivot around the axis P relative to the hub 250 between a so-called "flag" or "large pitch" position, in which the chord of the blade 20 is substantially orthogonal to a plane of rotation of the fan rotor 240 (and is therefore substantially parallel to the longitudinal axis X), and a so-called "sail" or "small pitch" position, in which the chord of the blade 20 is substantially contained within said plane of rotation of the fan rotor (and is therefore substantially orthogonal to the longitudinal axis X).

[0071] Preferably, each blade 20 is also capable of pivoting beyond the sail position, to a so-called "reverse" position, in which the chord of the blade 20 forms an angle, for example, approximately -5°, with the plane of rotation of the fan rotor 240, on the side of said plane opposite to that of the feathered position. Since the blades 20 are most often twisted, the chord used as a reference for measuring the pitch angle is, by convention, the chord of the blade at 75% of the radius of the fan rotor 240.

[0072] For this purpose, each blade 20 is fixed, as shown in Figure 3, to a mounting piece 210 located at the blade's base. This mounting piece 210 is rotatably mounted relative to the hub 250 around the pivot axis P. More precisely, the mounting piece 210 is rotatably mounted within a housing formed in the hub 250 by means of balls or other rolling elements.

[0073] With reference to Figure 3, the gas turbine engine 110 also includes a pitch change mechanism 1 to adjust the pitch angle of each blade 20 around its pivot axis P so as to adapt the performance of the turbomachine 110 to the different phases of flight.

[0074] The pitch change mechanism 1 includes a frame, a hydraulic cylinder 5 or control cylinder, a linkage system 21 and a cylinder piloting system 3.

[0075] The frame is integral with the hub 250 and is typically made up of a part of the hub 250. It is thus fixed relative to each pivot axis P and mobile in rotation relative to the casing 120.

[0076] The hydraulic cylinder 5 comprises a fixed main body or cylinder 51, integral with the frame. The cylinder 51 is cylindrical in shape and typically substantially centered on the longitudinal axis X.

[0077] The hydraulic cylinder 5 also includes a piston 52 that is movable in translation along the longitudinal axis X relative to the cylinder 51 between a first position and a second position. Optionally, the piston 52 is also movable in rotation about the longitudinal axis X through a small angle, for example on the order of 5°, relative to the fixed part 51.

[0078] The cylinder 51 defines an internal cavity. The piston 52 includes at least one partition housed inside said internal cavity and defining within the cylinder 51 an extension chamber 5c and a retraction chamber 5f.

[0079] Each chamber is designed to be supplied with a control fluid, typically an oil, so as to cause or control the movement of the piston 52 relative to the fixed part.

[0080] When the pressure in the extension chamber 5c is greater than the pressure in the retraction chamber 5f, the piston 52 translates in a first direction of movement, towards the first position, so that the linkage system 21 is configured to orient the blades 20 towards higher pitch angles.

[0081] When the pressure in the retraction chamber 5f is greater than the pressure in the extension chamber 5c, the piston 52 translates in a second direction of movement, opposite to the first direction of movement, towards the second position, so that the linkage system 21 is configured to take the blades 20 towards lower pitch angles.

[0082] According to a preferred embodiment, the piston 52 is fixed relative to the engine and the cylinder 51 is movable in translation. Thus, when the pressure in the extension chamber 5c is greater than the pressure in the retraction chamber 5f, the movable cylinder 51 translates in the first direction of movement, so that the linkage system 21 moves the blades 20 towards higher pitch angles, and conversely when the pressure in the retraction chamber 5f is greater than the pressure in the extension chamber 5c, the movable cylinder 51 translates in the second direction of movement, so that the linkage system 21 moves the blades 20 towards lower pitch angles.

[0083] The retraction chamber 5f has a first volume and the extension chamber 5c has a second volume, each of the first and second volumes depending on the position of the piston 52 in the main body 51.

[0084] Preferably, the hydraulic cylinder 5 is symmetrical, meaning that the sum of the first and second volumes is constant regardless of the position of the piston 52. Thus, it is possible to control the hydraulic cylinder 5 using a simple closed-loop system without an accumulator, by transferring the control fluid from one chamber 5f, 5c to the other. For this purpose, the internal cavity and the piston 52 are typically designed so that the two chambers 5f, 5c have the same cross-section.

[0085] The linkage system 21 connects the piston 52 to each blade 20 so as to convert the translation of the piston 52 along the longitudinal axis X and, where applicable, the rotation of the piston 52 around the longitudinal axis X into a rotation of each blade 20 around its pivot axis P.

[0086] In particular, the linkage system 21 connects the piston 52 to each blade 20 so as to convert:

[0087] - the translation of the piston 52 along the longitudinal axis X towards its first position by a rotation of the variable-pitch blade 20 around the pivot axis P towards the flag position, and

[0088] - the translation of the piston 52 along the longitudinal axis X towards its second position in a rotation of the variable pitch blade 20 around the pivot axis P towards the sail position.

[0089] It is understood here that such a linkage system 21 can be adapted to the embodiment in which the cylinder 51 is mobile in translation and the piston 52 is fixed.

[0090] Typically, the linkage system 21 can be a crankshaft comprising a connecting rod 214 connected to the piston rod 53, and transmitting the force of the piston 52 to a crank 211 rotating about its axis at one end of the connecting rod 214, thus converting linear motion into rotary motion.

[0091] In the illustrated embodiment, the linkage system 21 includes a synchronizing ring 213 attached to the piston rod 53 and, for each of the blades 20, a linkage mechanism for the blade 20 to the synchronizing ring 213.

[0092] The synchronizing ring 213 extends in a radial plane around the piston 52. In particular, it is fixed to a longitudinal end of the piston rod 53.

[0093] Each linkage mechanism includes a first joint 215 attached to the piston 52, a second joint 212 attached to the blade 20, away from the pivot axis P of said blade 20, and a linking member 214 connecting the first joint 215 to the second joint 212.

[0094] The first joint 215 is supported by the synchronizing ring 213. It is, for example, a pivot joint or a ball joint. The second joint 212 can also be a pivot joint or a ball joint. It is eccentric relative to the pivot axis P.

[0095] The connecting member 213 has a first end articulated to the first joint 215 and a second end articulated to the second joint 212. Advantageously the connecting member 214 is rigid and of adjustable length, that is to say that the distance between the first and second ends can be modified, which allows its length to be precisely adjusted at rest so as to allow the pitch angle of each blade 20 to be controlled by the pitch change mechanism 1.

[0096] The connecting member 21 is here constituted by a connecting rod. In the example shown, each connecting mechanism also includes a crank 211 linking the attachment piece 210 to the second joint 212. The crank 211 is rigid and integral with the attachment piece 210. It extends, at least in part, in a direction orthogonal to the pivot axis P. It forms an arm for rotating the blade 20.

[0097] First method of implementation

[0098] Figure 4 illustrates the actuation system 1 according to a first embodiment of the invention.

[0099] The actuation system 1 includes a main pilot system 3 and an auxiliary pilot system 6 with a hydraulic block 4.

[0100] In the embodiment shown, the main control system 3 is a main motor pump group 3 or main electro-hydrostatic actuator (“electro-hydrostatic Actuation” or EHA in English) of the hydraulic cylinder 5.

[0101] The main motor-pump group 3 comprises an electric motor 31, a hydraulic pump 32 and a control unit 33.

[0102] The pump unit 3 is configured to control the position of the hydraulic cylinder 5. The control unit 33 includes an electronic control box configured to receive a position command from the centralized control system and to control the rotational speed of the electric motor 31 based on this position command. More specifically, the position of the hydraulic cylinder 5 is controlled by a centralized control system for the gas turbine engine 110. More generally, the main control system 3 includes upstream electronic control components that provide position control for the hydraulic cylinder 5.

[0103] The electric motor 31 is thus connected to the control unit 33. Preferably, the control unit 33 also includes a second electronic box also connected to the electric motor 31. This increases the level of redundancy and compensates for a failure of the other electronic box.

[0104] The hydraulic pump 32 is connected to the electric motor 31 and driven in rotation by the electric motor 31. The hydraulic pump 32 is typically a reversible bidirectional pump, that is to say, it is configured to inject the control fluid into the hydraulic block 4 and to reverse the fluid flow to draw the control fluid from the hydraulic block 4.

[0105] Alternatively, the main control system 3 may include a servovalve powered by a hydraulic pressure generation system. In this conventional embodiment, which is not shown, the hydraulic cylinder 5 is position-controlled by the servovalve.

[0106] The hydraulic block 4 is a hydraulic circuit configured to ensure the distribution of the control fluid from the main pilot system 3 to the hydraulic cylinder 5.

[0107] The actuation system 1 further includes a main reservoir 8. The main reservoir 8 ensures the compensation of pressure variations within the main hydraulic circuit 4a and the supply of the hydraulic pump 32. The main reservoir 8 is typically a low pressure type reservoir.

[0108] The actuation system 1 further includes a rotary hydraulic distributor 7 ("Rotary connection"). The rotary hydraulic distributor 7 is designed to ensure the transfer of the control fluid between the fixed reference point of the hydraulic supply source 3 connected to the frame, and the rotating reference point connected to the blower 200. To achieve this, the rotary hydraulic distributor 7 comprises a fixed part and a rotating movable part.

[0109] In the embodiment shown, the auxiliary pilot system 6 is also a motor-pump unit called the "auxiliary motor-pump unit" 6. Here, the auxiliary motor-pump unit 6 is also connected to the hydraulic block 4.

[0110] The auxiliary motor-pump unit 6 includes an auxiliary electric motor 61 and an auxiliary hydraulic pump 62. The auxiliary motor-pump unit 6 is configured to ensure the extension of the hydraulic cylinder 5 to the first position in which it is fully extended, in order to put the vane 20 in the flag position in the event of failure of the main motor-pump unit 3 or on instruction from the centralized control system.

[0111] The auxiliary electric motor 61 is preferably an AC motor driven directly by an AC power supply without control electronics. Alternatively, the auxiliary electric motor 61 can be connected to an auxiliary control unit (not shown) comprising an auxiliary electronic control box. The auxiliary electronic control box can be identical to the electronic control box 33 of the main pump unit 3. Preferably, the auxiliary electronic control box is separate from the electronic control box 33 of the main pump unit 3. This prevents a malfunction of the electronic control box 33 from affecting the operation of the auxiliary control system 6. Preferably, the auxiliary electric motor 61 is also controlled by a second auxiliary electronic control box.This increases the level of redundancy and limits the risk of failure of the auxiliary control system 6 and therefore of the actuation system 1.

[0112] The auxiliary hydraulic pump 62 can be a unidirectional pump. It is driven in rotation by the auxiliary electric motor 61.

[0113] In general, the hydraulic block 4 can be divided into two separate hydraulic circuits. The architecture of the hydraulic block 4 in the first embodiment is detailed in Figure 5. The hydraulic block 4 comprises a first hydraulic circuit, referred to as the main circuit 4a, and a second hydraulic circuit, referred to as the auxiliary circuit 4b. The main control system 3 is connected to the main circuit 4a, and the auxiliary control system 6 is connected to the auxiliary circuit 4b. The term "connected" means that elements are linked or connected hydraulically.

[0114] The main hydraulic circuit 4a typically includes a safety assembly 43 upstream of the hydraulic cylinder 5, comprising four check valves and one pressure relief valve, designed to protect the hydraulic circuit and its components from the risks of overpressure and cavitation. The safety assembly 43 may, more specifically, include two sets of check valves and one pressure relief valve.

[0115] The first set of check valves allows control fluid from the low-pressure circuit to flow in the event of low pressure on one of the upstream lines to the main pump 32. This enables the hydraulic line to be replenished and thus increases the pressure at the suction port of the hydraulic pump 32. This system prevents cavitation in the pump 32. The second set of check valves allows the control fluid, in the event of overpressure in one of the hydraulic lines, to be discharged into the low-pressure circuit via the pressure relief valve. The two check valves are arranged with opposite orientations to prevent overpressure from being sent to the other hydraulic line.In another configuration not shown, the safety assembly 43 may include two pressure relief valves on each line of the hydraulic pump 32 (suction and discharge), the upstream ports of the pressure relief valves being connected to the return circuit.

[0116] Preferably, the hydraulic block 4, and more specifically the main hydraulic block 4a, includes a mode selector valve 41 (MSV). In the illustrated embodiments, the mode selector valve 41 is a six-way, two-position, electrically actuated monostable hydraulic distributor. It allows selection of a "passive" operating mode (the valve 41 is in the rest position, not electrically powered, and isolates the hydraulic cylinder 5 from the hydraulic power supply 3) or an "active" operating mode (the valve 41 is electrically powered and connects the hydraulic cylinder 5 to the hydraulic power supply 3).

[0117] The mode selector valve 41 can be connected to the control unit 33, meaning that the position of the mode selector valve 41 depends on the solenoid being powered by the control unit 33. Preferably, the mode selector valve 41 has a double winding and is also controlled by the optional second electronic control unit. This increases the level of redundancy.

[0118] In a first position called the "active" position, the mode selection valve 41 is open, and the main pilot system 3 can generate the suction / discharge of the control fluid to the rotating hydraulic distributor 7.

[0119] In a second position called the "passive" position, the mode selection valve 41 is blocked, so that the main circuit 4a is isolated from the rotating hydraulic distributor 7.

[0120] In the "passive" position, a channel connecting the extension chamber 5c to the retraction chamber 5f, which includes a check valve, is established. The configuration of the valve 41 and the presence of the check valve allow, on the one hand, the control fluid contained in the extension chamber 5c of the hydraulic cylinder 5 to escape and thus prevent the vanes 20 from being moved towards the small-pitch zone. On the other hand, it allows the control fluid contained in the retraction chamber 5f of the hydraulic cylinder 5 to escape and thus allow the vanes 20 to be moved towards the flagging position.

[0121] The route including the check valve also includes a hydraulic restrictor, in order to limit the flow of fluid between chambers of the hydraulic cylinder 5.

[0122] The main circuit further includes a return line, connecting a return port of the mode selector valve 41 to the main reservoir 6 via a pressure relief valve. The return line is isolated from the hydraulic cylinder 5 when the mode selector valve 41 is in the "active" position, and allows control fluid to be returned to the main reservoir 6 when the mode selector valve 41 is in the "passive" position if the pressure in the circuit exceeds the opening pressure of the pressure relief valve. The pressure relief valve is configured to open only when the pressure in the return line is above a threshold pressure.

[0123] Thus, the main hydraulic circuit 4a shown makes it possible to ensure the locking in current position of the hydraulic cylinder 5, and in particular to prevent its retraction, while allowing its extension, i.e. an orientation of the vanes 20 towards the "flag" position by an independent auxiliary actuation system.

[0124] For example, the independent auxiliary actuation system can be an electromechanical actuator (EAAA) comprising a moving part capable of moving the moving part of the hydraulic cylinder 5 (piston 52 or cylinder 51, depending on the embodiment). The moving part of the auxiliary actuator can be mechanically connected to the moving part of the hydraulic cylinder 5, or, alternatively, can exert a force on a device fixed to the moving part of the hydraulic cylinder 5, to return the vanes 20 to the "feathered" position. This eliminates the need for an auxiliary hydraulic power supply and reduces common failure modes, offering a more robust solution, particularly in the event of a seizure of the auxiliary actuator.

[0125] The main circuit elements 4a as shown are optional. Here, the independent auxiliary actuation system is the auxiliary motor-pump unit 6 supplying the same hydraulic cylinder 5 as the main motor-pump unit 3.

[0126] The actuation system 1 further includes an auxiliary reservoir 9. The auxiliary reservoir 9 ensures the compensation of pressure variations within the auxiliary circuit 4b and the supply of the auxiliary hydraulic pump 62. The auxiliary reservoir 9 is typically a low-pressure type reservoir.

[0127] The hydraulic block 4, and more specifically the auxiliary hydraulic circuit 4b, includes a feathering selector valve 42 (FSV). The feathering selector valve 42 is a hydraulically piloted, monostable valve with four ports and two positions.

[0128] The feathering valve 42 includes a first position, called the isolation position, in which the auxiliary circuit 4b is not connected to the rotary hydraulic distributor 7. The isolation position is maintained by the force exerted by a return spring. The feathering valve 42 includes a second position, called the flow position, in which the control fluid can flow freely between the auxiliary circuit 4b and the rotary hydraulic distributor 7.

[0129] The flagging valve 42 is controlled by the discharge pressure of the auxiliary motor-pump unit 6 via a solenoid valve 44 (“Pilot Solenoid Valve” or PSV).

[0130] The solenoid valve 44 typically comprises a spring-returned sleeve-spool assembly and an electromagnetic actuating coil or solenoid, the power supply of which is controlled by the electronic control unit of the auxiliary control unit. Preferably, the solenoid valve 44 has a double winding and is also controlled by the second auxiliary electronic control unit. This increases the level of redundancy.

[0131] The solenoid valve 44 has three ports and two positions. In the first position, referred to as the passive position, the hydraulic pilot port is connected to the auxiliary reservoir 9. The pilot pressure of the valve 42 is then low, and the spring of the feathering valve 42 holds it in the isolated position. In the second position, referred to as the active position, the hydraulic pilot port is connected to the discharge port of the auxiliary pump unit 6. The pressure generated by the auxiliary pump unit 6 then opens the feathering valve 42 to the operating position.

[0132] In this first embodiment, the auxiliary control system 6, the auxiliary tank 9, and the auxiliary circuit 4b are in the fixed frame, i.e., integral with the frame and therefore with the structure of the gas turbine engine 110. This first embodiment has the advantage of not requiring the presence of electronics, particularly the auxiliary electronic control unit, in the rotating frame. Furthermore, the presence of massive components such as the auxiliary tank 9 or the auxiliary pump unit 6 in the rotating frame can cause imbalances if they are misaligned with respect to the longitudinal axis X, which adds constraints to the dimensioning of the gas turbine engine 110.

[0133] The actuation system 1 further includes a rotary hydraulic distributor 7. The rotary hydraulic distributor 7 is designed to ensure the transfer of the control fluid between the fixed reference point and the rotating reference point linked to the vanes 20. It also ensures the connection of the main circuit and the auxiliary circuit with the hydraulic cylinder 5.

[0134] The architecture of the rotary hydraulic distributor 7 in the first embodiment is shown in Figure 6. The rotary hydraulic distributor 7 includes an isolation valve 71 (or "Isolation Valve" or IV). The isolation valve 71 is a hydraulically piloted, monostable distributor with four ports and two positions. The isolation valve 71 is capable of selectively adopting a first and a second configuration. It includes an actuating element configured to control the configuration of the isolation valve 71. The actuating element includes, for example, a spring exerting a restoring force that maintains the isolation valve 71 in the first configuration by default.

[0135] The rotary hydraulic distributor 7, like the isolation valve 71, includes a first supply route A and a second supply route B. The supply routes A, B hydraulically connect the isolation valve 71 to the main pilot system 3 via the main circuit 4a.

[0136] The rotary hydraulic distributor 7, like the isolation valve 71, includes a return path R. The return path R hydraulically connects the isolation valve 71 to the return port of the auxiliary pilot system 6 via the auxiliary circuit 4b.

[0137] The rotary hydraulic distributor 7, like the isolation valve 71, includes an extension channel C connecting the isolation valve 71 and the extension chamber 5c of the hydraulic cylinder 5, and a retraction channel F connecting the isolation valve 71 and the retraction chamber 5f of the hydraulic cylinder 5.

[0138] The rotary hydraulic distributor 7 also includes an auxiliary supply line S (for "supply") connected to the supply port of the auxiliary pilot system 6 via the auxiliary circuit 4b. The auxiliary supply line S is connected to the hydraulic pilot line of the isolation valve 71 and to the extension chamber 5c of the hydraulic cylinder 5 via the check valve 72. The auxiliary supply line corresponds to an extension line of the hydraulic cylinder 5 so that it can reach a feathering position of the vanes 20.

[0139] Operation of isolation valve 71 in the first configuration

[0140] With reference to Figure 6, when the isolation valve 71 is in the first configuration, it permits the passage of fluid between the supply paths A, B connected to the ports of the hydraulic pump 32 to the hydraulic cylinder 5, and it isolates the return line R from the auxiliary circuit 4b.

[0141] In other words, when the feathering valve 42 is passive (i.e., in the blocked position), the auxiliary circuit 4b is isolated from the hydraulic cylinder 5. Port A, connected to the hydraulic pump 32 of the main circuit 4a via the first supply line A, is hydraulically connected to port C, known as the extension port, which is connected to the extension chamber 5c of the hydraulic cylinder 5 via the extension line. Thus, the hydraulic pump 32 of the main pilot system 3 can either deliver fluid to the extension chamber 5c or draw fluid from the extension chamber 5c.

[0142] Port B, connected to the hydraulic pump 32 of the main circuit 4a via the second supply line B, is linked to port F, known as the retraction port, which is hydraulically connected to the retraction chamber port 5f of the hydraulic cylinder 5 via the retraction line. Thus, the hydraulic pump 32 of the main control system 3 can draw fluid from the retraction chamber 5f or discharge fluid into the retraction chamber 5f.

[0143] Port R, connected to the auxiliary circuit via the return line, is isolated. Therefore, in the event of a pipe rupture in the auxiliary circuit lines, the main control system 3 can continue to operate the hydraulic cylinder 5, allowing at least its movement to the flagged position. With port R isolated, the main circuit 4a is protected from external leaks in the auxiliary circuit.

[0144] The non-return valve 72 also prevents leaks into the auxiliary circuit 4b, as the control fluid cannot flow into the auxiliary circuit 4b.

[0145] Preferably, the isolation valve 71 is in the first default configuration, due to the return force exerted by the spring. The first configuration is known as the passive position.

[0146] Operation of the isolation valve in the second configuration

[0147] With reference to Figure 7, when the isolation valve 71 is in the second configuration, in the active position, it isolates the supply paths A, B of the main circuit 4a connected to the ports of the hydraulic pump 62, and it allows the passage of the control fluid between the retraction chamber 5f of the hydraulic cylinder 5 and the return port of the auxiliary circuit 4b via the return path R.

[0148] Typically, the isolation valve 71 switches to the second configuration after activation of the solenoid valve 44 and pressurization of the supply line of the hydraulic pump 62 of the auxiliary circuit, the active feathering valve 42 then being switched to the passing position.

[0149] Thus, the actuating member of the isolation valve 71 can steer the isolation valve 71 into the second configuration when the pressure in the auxiliary supply path is greater than a threshold pressure value, the isolation valve 71 being maintained in the first configuration otherwise.

[0150] Ports A and B connected to the main circuit 4a are isolated. Therefore, the main circuit 4a and the main control system 3 are isolated from the hydraulic cylinder 5. The hydraulic cylinder 5 is no longer position-controlled by the main control system 3.

[0151] Port F, connected to the retraction chamber port 5f via the retraction line, is connected to port R of the return line. Thus, the retraction chamber 5f of the hydraulic cylinder 5 is connected to the auxiliary circuit 4b. In particular, if the auxiliary hydraulic pump 62 is unidirectional, the control fluid can flow from the retraction chamber 5f to the return line.

[0152] Port C connected to the port of the extension chamber 5c is isolated and the extension chamber 5c of the hydraulic cylinder 5 is supplied by the auxiliary extension route including the check valve 72, connecting to the supply port of the auxiliary circuit 4b.

[0153] The isolation valve 71 switches to the second configuration when the pressure in the auxiliary supply line exceeds a threshold pressure value, the hydraulic pilot line exerting sufficient pressure to compress the spring and change the position of the isolation valve 71. The second configuration corresponds to an active position.

[0154] Thus, in the event of a pipe rupture in the lines of the main circuit or a malfunction of the main piloting system 3, the auxiliary piloting system 6 can return the hydraulic cylinder 5 to the "flag" position, the auxiliary circuit 4b being protected from external leaks or from the erratic behavior of the main circuit 4a by isolating the lines of the main circuit 4a.

[0155] Second embodiment

[0156] In a second embodiment illustrated in Figure 8, the auxiliary control system 6 is arranged in the rotating frame. The auxiliary circuit 4b is then included in the rotating hydraulic distributor 7. This embodiment has the advantage that the lines of the auxiliary hydraulic circuit 4b connected to the rotating hydraulic distributor 7 are separated from the lines of the main hydraulic circuit 4a connected to the rotating hydraulic distributor 7, thus limiting the risk of simultaneous rupture of all these lines and further reducing the common failure modes between the main and auxiliary actuation systems. The main control system 3 and the main circuit 4a are in the fixed frame attached to the chassis. The elements of the main circuit 4a are identical in both embodiments and will not be detailed.More generally, the elements common to both embodiments will not be described again. With reference to Figure 9, the auxiliary motor-pump unit 6 and the auxiliary reservoir 9 are in the rotating frame of reference, near the hydraulic cylinder 5. The auxiliary motor-pump unit 6 is connected to the rotating hydraulic distributor 7.

[0157] The main motor-pump unit 3 is connected to the hydraulic block 4 corresponding to the main circuit 4a, and they are arranged in the fixed frame of reference. Referring to Figure 10, the rotary hydraulic distributor 7 comprises the auxiliary hydraulic circuit 4b.

[0158] The present invention can advantageously be integrated into different aircraft engine architectures, for example into a turboprop engine comprising a fan arranged in a casing, or into the new generations of aircraft engines with uncased fans (called "open fan") in which the fan 200 is not surrounded by a casing.

Claims

DEMANDS 1. Actuation system (1) for adjusting the pitch of fan blades (200) of an aircraft engine comprising a hydraulic cylinder (5), the hydraulic cylinder (5) comprising a cylinder and a piston, the piston delimiting within the cylinder a retraction chamber (5f) and an extension chamber (5c), each of the retraction chamber (5f) and the extension chamber (5c) being adapted to be supplied with a control fluid, so as to cause a displacement of the piston relative to the cylinder in a first direction of movement when a pressure of the control fluid in the extension chamber (5c) is greater than a pressure of the control fluid in the retraction chamber (5f) and to cause a displacement of the piston relative to the cylinder in a second direction of movement, opposite to the first direction of movement,when the control fluid pressure in the retraction chamber (5f) is greater than the control fluid pressure in the expansion chamber (5c); the actuation system (1) further comprising, - a main hydraulic circuit (4a); - an auxiliary hydraulic circuit (4b); - a rotary hydraulic distributor (7) comprising a movable, rotatable part configured to be driven in rotation by the blower (200), the hydraulic distributor (7) comprising - an isolation valve (71) capable of selectively adopting a first configuration and a second configuration, the isolation valve (71) comprising an actuating element configured to control the configuration of the isolation valve (71), and - a first supply port (A) and a second supply port (B), each connected to the main hydraulic circuit (4a); - an expansion port (C) connected to the expansion chamber (5c); - a retraction port (F) connected to the retraction chamber (5f); - a return port (R) connected to the auxiliary hydraulic circuit (4b); - an auxiliary supply line connected to the auxiliary hydraulic circuit (4b), comprising an actuation line connecting the auxiliary hydraulic circuit (4b) to the actuating member of the isolation valve (71), and an auxiliary extension line connecting the auxiliary hydraulic circuit (4b) to the extension chamber (5c) via a check valve (72) configured to prevent circulation of the control fluid from the extension chamber (5c) to the auxiliary hydraulic circuit (4b); so that - when the isolation valve (71) is in the first configuration, the first supply port (A) is hydraulically connected to the extension port (C) and the second supply port (B) is hydraulically connected to the retraction port (F), the return port (R) being isolated, so that the hydraulic cylinder (5) is configured to be position-controlled by a control fluid from the main hydraulic circuit (4a); and - when the isolation valve (71) is in the second configuration, the return port (R) is hydraulically connected to the retraction port (F), the extension port (C), the first supply port (A) and the second supply port (B) being isolated, so that the piston of the hydraulic cylinder (5) can move in the first direction of travel by action of a control fluid from the auxiliary hydraulic circuit (4b), the blower blade orienting itself towards a large pitch position, and the auxiliary hydraulic circuit (4b) not being hydraulically connected with the main hydraulic circuit (4a).

2. Actuation system (1) according to claim 1, further comprising an auxiliary piloting system (6) configured to pilot a circulation of the control fluid in the auxiliary hydraulic circuit (4b).

3. Actuation system (1) according to claim 2, further comprising an auxiliary control unit, and in which the auxiliary piloting system (6) comprises an auxiliary electric motor (61) and an auxiliary hydraulic pump (62), the auxiliary electric motor (61) being configured to drive the auxiliary hydraulic pump (62) in rotation, and the auxiliary control unit being configured to pilot the auxiliary electric motor (31) so as to modify the pressure of the auxiliary supply path, corresponding to an extension line of the hydraulic cylinder (5) so that it can reach a feathering position of the blades (20).

4. Actuation system (1) according to any one of claims 1 to 3, wherein the auxiliary hydraulic circuit (4b) comprises a feathering valve (42) connected to the auxiliary supply line, and a solenoid valve (44) configured to actuate the feathering valve (42) so as to change the pressure of the auxiliary supply line, and wherein the feathering valve (42) is actuated between a passing position in which the isolation valve (71) is in the second configuration, and a blocking position in which the auxiliary hydraulic circuit (4b) is isolated from the isolation valve (71).

5. Actuation system (1) according to claim 4, wherein the auxiliary hydraulic circuit (4b) is arranged in the hydraulic distributor (7), so that the feathering valve (42) and the solenoid valve (44) are configured to be driven in rotation by the blower (200).

6. Actuation system (1) according to any one of claims 1 to 5, wherein the main hydraulic circuit (4a) comprises a safety hydraulic circuit including at least two check valves and one of the following: two check valves and one pressure relief valve, and at least two pressure relief valves.

7. Actuation system (1) according to any one of claims 1 to 6, further comprising a main pilot system (3) configured to pilot a circulation of the control fluid in the main hydraulic circuit (4a), and in which the main hydraulic circuit (4a) comprises a distribution valve (41) adapted to selectively adopt an active position and a passive position, such that, when the distribution valve (41) is in the active position, the hydraulic cylinder (5) is configured to be position-controlled by the main pilot system (3), and when the distribution valve (41) is in the passive position, the control fluid can only circulate from the retraction chamber (5f) to the extension chamber (5c).

8. Actuating system (1) according to any one of claims 1 to 7, wherein the actuating member is further configured to steer the isolation valve in the second configuration when a pressure in the auxiliary supply path is greater than a threshold pressure value, the isolation valve being maintained in the first configuration otherwise.

9. Aircraft engine comprising a fan (200) and a pitch control actuation system (1) according to any one of claims 1 to 8, the fan (200) being mounted to rotate movably about a longitudinal axis (X), and comprising a plurality of blades (20), each blade (20) extending along its own radial axis (P), such that, when the isolation valve (71) is in the second configuration, each blade (20) is configured to be rotated about its own radial axis (P) by the actuation system (1) so as to orient itself parallel to the longitudinal axis (X) towards the high pitch position.

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