AIRCRAFT TURBOMACHINE

Abstract

Aircraft turbomachine (1) (2) comprising: - a propulsion rotor (3) including at least one variable-pitch blade (4); - a blade (4) pitch adjustment device (6), this adjustment device (6) including a hydraulic actuator (9) controlled by a main hydraulic circuit (11) and an auxiliary hydraulic circuit (12), the main circuit (11) being supplied by a main oil reservoir (14) and including a blade (4) pitch adjustment pump (15), the main and auxiliary circuits (11, 12) having a common section (13); - a blade (4) pitch locking device (16); characterized in that the main circuit (11) includes a shut-off valve (17) configured to occupy an inactive position and an active position in which the shut-off valve (17) hydraulically isolates the adjustment pump (15) from the main reservoir (14). Figure for the abstract: 2

Description

Title of the invention: AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to an aircraft turbomachine comprising a propulsion rotor comprising at least one variable-pitch blade, a device for adjusting the blade pitch and a device for locking the blade pitch. Technical background

[0002] An aircraft turbomachine may comprise a propulsion rotor provided with variable-pitch blades, i.e. blades whose pitch (and more precisely the pitch angle) is adjustable according to the flight parameters, so as to optimize the performance of the turbomachine.

[0003] For example, the propulsion rotor may be a fan or a propeller which is rotated by a power turbine of the turbomachine via a speed reducer.

[0004] Such a turbomachine comprises a device for adjusting the pitch of the blades. The adjustment device comprises one or more actuators and a mechanism specific to each of the blades, this mechanism being configured to transform the movement initiated by the actuator(s) into a rotational movement of the corresponding blade.

[0005] Traditionally, the actuator(s) are hydraulic actuators controlled by a main hydraulic circuit and an auxiliary hydraulic circuit.

[0006] The auxiliary circuit is used to put the blades in the flag position in the event of failure of the main circuit. The main and auxiliary circuits generally have a common part which notably includes a control unit, an oil transfer device, and the hydraulic actuator(s).

[0007] The main circuit is supplied by a main oil reservoir and includes in particular a blade timing adjustment pump which is mechanically driven by the accessory box of the turbomachine. The main oil reservoir is also used to supply the lubrication circuit of the turbomachine, this lubrication circuit being used in particular to lubricate the speed reducer (toothed wheels and bearings) and bearings guiding different shafts of the turbomachine.

[0008] A hydraulic leak in the common part of the main and auxiliary circuits is a possible failure which would render these two circuits unusable. The blades would then be free to move around their axis of rotation, which is not desirable (risk of significant drag and / or rotor overspeed). To avoid this, it is known to install a locking device specific to each of the blades, these locking devices locking being configured to lock the blade timing, in particular in the event of a simultaneous failure of both circuits.

[0009] Engine manufacturers note that it is also essential to quickly stop this hydraulic leak, otherwise the main reservoir will be partially or completely emptied, the main reservoir being, as a reminder, also used by the lubrication circuit. An oil level that is too low in the main reservoir could be detrimental to the speed reducer and the various bearings due to suboptimal or non-existent lubrication.

[0010] The objective of the present invention is therefore to provide a simple, effective and economical solution making it possible to respond to the aforementioned problem. Summary of the invention

[0011] The invention thus proposes an aircraft turbomachine comprising: - a propulsion rotor comprising at least one variable-pitch blade; - a device for adjusting the blade timing, this adjustment device being integral with the rotor and comprising a hydraulic actuator controlled by a main hydraulic circuit and an auxiliary hydraulic circuit, the main circuit being supplied by a main oil reservoir and comprising a pump for adjusting the blade timing, the auxiliary circuit being intended for setting the blade in the flag position, the main and auxiliary circuits having a common part; - a blade timing locking device configured to occupy an inactive position and an active position in which the locking device locks the blade timing, in particular in the event of a hydraulic leak in the common part of the circuits; characterized in that the main circuit comprises a shut-off valve configured to occupy an inactive position and an active position in which the shut-off valve hydraulically isolates the control pump from the main reservoir, in particular in the event of a hydraulic leak in the common part of the circuits.

[0012] Such a shut-off valve allows, in its active position, the hydraulic isolation of the control pump from the main reservoir by blocking the passage of oil. This is particularly advantageous in the event of a hydraulic leak in the common part of the circuits, so as not to empty the main reservoir, and thus allow the various elements (reducer, bearings, etc.) of the lubrication circuit to continue to be lubricated correctly.

[0013] The turbomachine according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: - the shut-off valve is located between the main tank and the control pump; - the main circuit includes a feed pump, the shut-off valve being located between the feed pump and the control pump; - the propulsion rotor is rotated by a power turbine via a speed reducer, the reducer being lubricated via a lubrication circuit which is supplied by the main tank; - the turbomachine comprises several bearings configured to guide in rotation several moving shafts of the turbomachine, the bearings being lubricated via the lubrication circuit; - the common part of the circuits comprises a control unit, an oil transfer bearing and the actuator, the control unit being controlled by a turbomachine control computer; - the control pump is mechanically driven by an accessory box of the turbomachine, the accessory box itself being mechanically driven by a gas generator of the turbomachine; - the auxiliary circuit is supplied by an auxiliary oil tank and includes an auxiliary pump mechanically driven by an electric motor; - the locking device and the shut-off valve occupy an active position when the oil pressure in the common part of the circuits is lower than a predetermined threshold value; - oil pressure is measured redundantly by two independent pressure sensors; - the shut-off valve is controlled redundantly by a control unit which is common to the main and auxiliary circuits, and / or a turbomachine control computer; - the propulsive rotor is a propulsive fan or a propulsive propeller. Brief description of the figures

[0014] The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

[0015] [Fig-1] [Fig.l] is a schematic view of an aircraft turbomachine according to the invention;

[0016] [Fig.2] [Fig.2] is a schematic detail view of [Fig.l];

[0017] [Fig.3] [Fig.3] is a schematic view similar to [Fig.2] which illustrates a variant of implementation. Detailed description of the invention

[0018] In [Fig.l] is shown schematically and partially a turbomachine 1 of aircraft 2 which is defined along a longitudinal axis X.

[0019] The turbomachine 1 comprises a propulsion rotor 3 which is rotatable about the axis X relative to a fixed structure of the turbomachine 1. The rotor 3 comprises an annular row of variable-pitch blades 4, each blade 4 being pitched about an axis of rotation Y which is substantially perpendicular to the axis X. The rotor 3 is driven in rotation by a power turbine associated with a gas generator of the turbomachine 1. The power turbine and the gas generator are not shown in the figures for reasons of clarity.

[0020] The propulsion rotor 3 may be a ducted fan, and thus be part of a turbojet, for example a UHBR type turbojet for “Ultra High Bypass Ratio”.

[0021] The propulsion rotor 3 may be an unducted fan, and thus be part of a turbomachine of the UDF “Unducted Fan” type, of the USF “Unducted Single Fan” type, or of the “Open Rotor” type.

[0022] The rotor 3 can also be a shrouded or unshrouded propeller.

[0023] The turbomachine could comprise two or more propulsive rotors 3 which are counter-rotating or not.

[0024] The rotor(s) 3 may be arranged upstream or downstream of the assembly comprising the gas generator and the power turbine.

[0025] According to the embodiments illustrated in the figures, the rotor 3 is rotated by the power turbine via a speed reducer 5. The speed reducer 5 makes it possible to reduce the rotational speed of the rotor 3 relative to that of the power turbine, while increasing its torque. The speed reducer 5 is for example an epicyclic gear reducer which has the advantage of having a high reduction ratio while being compact.

[0026] The gas generator conventionally comprises, from upstream to downstream, at least one compressor, a combustion chamber, and at least one expansion turbine (or high pressure turbine). The compressor and the expansion turbine are rotationally connected to each other via a transmission shaft.

[0027] The power turbine is independent of the gas generator, and in other words the power turbine is not linked in rotation with the gas generator.

[0028] The rotor 3 can operate in “propulsor mode” so as to propel or move the aircraft 2 forward, and in “reverser” mode so as to brake the aircraft 2 when it lands.

[0029] The turbomachine 1 comprises a device 6 for adjusting the pitch of the blades 4, better known by the English acronyms FPAS for “Fan Pitch Actuation System” or PCM for “Pitch Change Mechanism”. The adjustment device 6 is integral with the rotor 3, and is therefore placed in a rotating reference frame 7. The adjustment device 6 comprises one or more hydraulic actuators 9 and a mechanism 10 specific to each of the blades 4, this mechanism 10 being configured to transform the movement initiated by the actuator(s) 9 into a rotational movement of the corresponding blade 4. The movement of the actuator(s) 9 thus makes it possible to synchronize the setting of all the blades 4 via in particular the different mechanisms 10.

[0030] The hydraulic actuator 9 can be linear or rotary.

[0031] According to the embodiments illustrated in the figures and in particular [Fig.l], the adjustment device 6 comprises a single actuator 9 which is a hydraulic and linear cylinder. Each mechanism 10 may in particular comprise a crank having a first end linked to a pivot of the blade and a second end (off-centered relative to the first end) linked to a synchronization ring which is controlled by the actuator 9.

[0032] The actuator(s) 9 are controlled by a main hydraulic circuit 11 and an auxiliary hydraulic circuit 12. The auxiliary circuit 12 is used to put the blades 4 in the flag position in the event of failure of the main circuit 11. The main and auxiliary circuits 11, 12 have a common part 13 which comprises different hydraulic components useful to the two circuits 11, 12. The main circuit 11 is supplied by a main oil reservoir 14 and comprises a pump 15 for adjusting the pitch of the blades 4.

[0033] The turbomachine 1 also comprises a locking device 16 for the timing of the blades 4. This locking device 16 may be common to all the blades 4 or specific to each of the blades 4.

[0034] According to the embodiments illustrated in the figures and in particular [Fig.l], each blade 4 is associated with a locking device 16. The locking device 16 is configured to occupy an inactive position in which the locking device 16 authorizes the setting of the blade 4, and an active position in which the locking device 16 locks the setting of the blade 4, in particular in the event of a hydraulic leak in the common part 13 of the circuits 11, 12.

[0035] More generally, the various locking devices 16 are in the active position as soon as the two main and auxiliary circuits 11, 12 fail simultaneously, to avoid excessive drag and / or overspeed of the rotor 3.

[0036] By way of example, a locking device 16 comprises a disc connected to the blade, this disc being inserted between two jaws secured to a ring carrying the blade, one of the jaws being fixed, the other being movable and controlled by an actuator. In the active position, the jaws clamp the disc under the impulse of the actuator.

[0037] According to the invention, the main circuit 11 comprises a stop valve 17 (or isolation valve) configured to occupy an inactive position and an active position in which the stop valve 17 hydraulically isolates the control pump 15 from the reservoir. main 14, in particular in the event of a hydraulic leak in the common part 13 of circuits 11, 12.

[0038] Such a stop valve 17 makes it possible, in its active position, to hydraulically isolate the control pump 15 from the main reservoir 14 by blocking the passage of oil. This is particularly advantageous in the event of a hydraulic leak in the common part 13 of the circuits 11, 12, so as not to empty the main reservoir 14, and thus allow the various elements (reducer, bearings, etc.) of the lubrication circuit to continue to be lubricated correctly.

[0039] By convention, in the present application, the terms “upstream” and “downstream” are defined in relation to the direction of circulation of the gases in the turbomachine 1 and to the direction of circulation of the oil in each of the circuits 11, 12, 19.

[0040] Advantageously, the stop valve 17 is located between the main reservoir 14 and the control pump 15.

[0041] The main circuit 11 may comprise a booster pump 18 (or pressure booster pump) upstream of the control pump 15. The stop valve 17 is then located between the booster pump 18 and the control pump 15.

[0042] The turbomachine 1 may comprise a lubrication circuit 19 which is separate from the main and auxiliary circuits 11, 12. The lubrication circuit 19 is supplied by the main oil reservoir 14 and is notably used to lubricate the speed reducer 5 (toothed wheels and bearings) and bearings 20 guiding different moving shafts of the turbomachine 1.

[0043] The common part 13 of the circuits 11, 12 may comprise a control unit 21 and / or an oil transfer bearing 22 (rotating connection or rotating joint).

[0044] The control unit 21 is also known by the English acronym PCU for “Power Control Unit”. The control unit 21 makes it possible in particular to direct the pressurized oil via different distributors. The control unit 21 is controlled by a control computer 23 of the turbomachine 1, this computer 23 being better known by the English acronym FADEC for “Full Authority Digital Engine Control”. Advantageously, the control computer 23 comprises two separate channels operating in parallel, to ensure redundancy in the event of failure of one or other of the channels.

[0045] The oil transfer bearing 22 is also known by the English acronym OTB for “Oil Transfer Bearing”. The oil transfer bearing 22 makes it possible to transfer the oil from the fixed reference mark 8 (linked to the structure) to the rotating reference mark 7 (linked to the rotor 3).

[0046] Advantageously, the control pump 15 is mechanically driven by an accessory box 24 of the turbomachine 1. The accessory box 24 is also known by the English acronym AGB for “Accessory Gear Box”. conventionally, the accessory box 24 is mechanically driven by the gas generator of the turbomachine 1.

[0047] Advantageously, the auxiliary circuit 12 is supplied by an auxiliary oil tank 25 (separate from the main oil tank 14) and comprises an auxiliary pump 26 mechanically driven by an electric motor 27.

[0048] Advantageously, the locking devices 16 and the stop valve 17 occupy an active position when the oil pressure in the common part 13 of the circuits 11, 12 is lower than a predetermined threshold value (or reference value). The oil pressure is preferably measured redundantly by two pressure sensors independent of each other, each pressure sensor being connected to the control unit 21 and / or to one of the channels of the control computer 23.

[0049] The shut-off valve 17 can be controlled redundantly by the control unit 21 and / or the control computer 23.

[0050] Advantageously, the stop valve 17 is tested before each flight of the aircraft 2, to verify its correct operation.

[0051] According to the embodiments illustrated in the figures, and in particular figures 2 and 3, the main circuit 11 successively comprises, from the main tank 14 to the common part 13 of the circuits 11, 12, a volumetric booster pump 18, a filter 28, an air / oil heat exchanger 29, the stop valve 17 and the adjustment pump 15. The main circuit 11 further comprises a bypass valve 30 in parallel with the stop valve 17 and the adjustment pump 15.

[0052] The feed pump 18 and the control pump 15 are mechanically driven by the accessory box 24 of the turbomachine 1.

[0053] As illustrated in Figures 2 and 3, the auxiliary circuit 12 successively comprises, from the auxiliary tank 25 to the common part 13 of the circuits 11, 12, a volumetric auxiliary pump 26 and a bypass valve 31.

[0054] The auxiliary pump 26 is mechanically driven by an electric motor 27.

[0055] As illustrated in more detail in [Fig. 1], the common part 13 of the circuits 11, 12 successively comprises a control unit 21, an oil transfer bearing 22 and the hydraulic cylinder (adjustment device 6).

[0056] As illustrated in Figures 2 and 3, the turbomachine 1 comprises a lubrication circuit 19 which successively comprises, from the main reservoir 14 to the bearings 20 and the reducer 5 to be lubricated, a feed pump 32, a filter 33, an air / oil heat exchanger 34 and two fuel / oil heat exchangers 35. The speed reducer 5 is supplied via a tapping or connection located between the two fuel / oil heat exchangers 35.

[0057] [Fig.l] illustrates, via dotted areas, the different elements located in the fixed reference frame 8 (linked to the fixed structure) and the different elements located in the rotating reference mark 7 (linked to rotor 3). The oil transfer bearing 22 straddles the fixed reference mark 8 and the rotating reference mark 7 because it comprises a fixed member secured to the fixed reference mark 8 and a movable member secured to the rotating reference mark 7, to allow the transfer of oil from the fixed reference mark 8 to the rotating reference mark 7. In the fixed reference mark 8, there are in particular the main reservoir 14, the feed pump 18, the adjustment pump 15, the shut-off valve 17, the control unit 21 and the control computer 23. In the rotating reference mark 7, there are in particular the propulsion rotor 3, the adjustment device 6 (actuator 9 and mechanisms 10) and the locking devices 16.

[0058] As illustrated in [Fig.l], the control unit 21 is controlled by a FADEC type control computer 23 which is explained above. The control computer 23 receives in particular information on the setting of the blades 4 via different angular position sensors 36.

[0059] The shut-off valve 17 can occupy an inactive position in which it allows the passage of oil and an active position in which it blocks the passage of oil, so as to hydraulically isolate the control pump 15 from the main reservoir 14.

[0060] As indicated above, the stop valve 17 occupies an active position in the event of a hydraulic leak in the common part 13 of the circuits 11, 12, and for example a leak at the control unit 21 or the oil transfer bearing 22 or the actuator 9, or even at the level of a pipe connecting the aforementioned members. The stop valve 17 can also be in the active position when one of the hydraulic components of the common part 13 is faulty.

[0061] According to the embodiment illustrated in Figures 1 and 2, the stop valve 17 is controlled redundantly by the FADEC type control computer 23. As indicated above, the control computer 23 comprises two separate channels operating in parallel, to ensure redundancy in the event of failure of one or other of the channels.

[0062] According to the embodiment variant illustrated in [Fig. 3], the shut-off valve 17 is controlled redundantly by the control unit 21.

Claims

Claims

1. Turbomachine (1) for an aircraft (2) comprising: - a propulsion rotor (3) comprising at least one variable-pitch blade (4); - a device (6) for adjusting the pitch of the blade (4), this adjustment device (6) being integral with the rotor (3) and comprising a hydraulic actuator (9) controlled by a main hydraulic circuit (11) and an auxiliary hydraulic circuit (12), the main circuit (11) being supplied by a main oil reservoir (14) and comprising a pump (15) for adjusting the pitch of the blade (4), the auxiliary circuit (12) being intended for setting the blade (4) in the flag position, the main and auxiliary circuits (11, 12) having a common part (13);- a locking device (16) for the timing of the blade (4) configured to occupy an inactive position and an active position in which the locking device (16) locks the timing of the blade (4), in particular in the event of a hydraulic leak in the common part (13) of the circuits (11, 12); characterized in that the main circuit (11) comprises a shut-off valve (17) configured to occupy an inactive position and an active position in which the shut-off valve (17) hydraulically isolates the adjustment pump (15) from the main reservoir (14), in particular in the event of a hydraulic leak in the common part (13) of the circuits (11, 12).;

2. Turbomachine (1) according to claim 1, characterized in that the shut-off valve (17) is located between the main reservoir (14) and the control pump (15).

3. Turbomachine (1) according to the preceding claim, characterized in that the main circuit (11) comprises a feed pump (18), the shut-off valve (17) being located between the feed pump (18) and the control pump (15).

4. Turbomachine (1) according to one of the preceding claims, characterized in that the propulsion rotor (3) is driven in rotation by a power turbine via a speed reducer (5), the reducer (5) being lubricated via a lubrication circuit (19) which is supplied by the main tank (14).

5. Turbomachine (1) according to the preceding claim, characterized in that the turbomachine (1) comprises several bearings (20) configured to guide in rotation several moving shafts of the turbomachine (1), the bearings (20) being lubricated via the lubrication circuit (19).

6. Turbomachine (1) according to one of the preceding claims, characterized in that the common part (13) of the circuits (11, 12) comprises a control unit (21), an oil transfer bearing (22) and the actuator (9), the control unit (21) being controlled by a control computer (23) of the turbomachine (1).

7. Turbomachine (1) according to one of the preceding claims, characterized in that the control pump (15) is mechanically driven by an accessory box (24) of the turbomachine (1), the accessory box (24) itself being mechanically driven by a gas generator of the turbomachine (1).

8. Turbomachine (1) according to the preceding claim, characterized in that the auxiliary circuit (12) is supplied by an auxiliary oil tank (25) and comprises an auxiliary pump (26) mechanically driven by an electric motor (27).

9. Turbomachine (1) according to one of the preceding claims, characterized in that the locking device (16) and the shut-off valve (17) occupy an active position when the oil pressure in the common part (13) of the circuits (11, 12) is lower than a predetermined threshold value.

10. Turbomachine (1) according to the preceding claim, characterized in that the oil pressure is measured redundantly by two pressure sensors independent of each other.

11. Turbomachine (1) according to one of the preceding claims, characterized in that the shut-off valve (17) is controlled redundantly by a control unit (21) which is common to the main and auxiliary circuits (11, 12), and / or a control computer (23) of the turbomachine (1).

12. Turbomachine (1) according to one of the preceding claims, characterized in that the propulsive rotor (3) is a propulsive fan or a propulsive propeller.

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