TURBOMACHINE INCLUDING A LUBRICATION UNIT AND A SPEED REDUCER

Abstract

The invention relates to a turbomachine comprising: - a lubrication chamber (17) in which a speed reducer (12) is located, - a main lubrication circuit and an auxiliary lubrication circuit connected to the lubrication chamber (17), the auxiliary circuit being connected to an auxiliary reservoir (31) comprising: an internal cavity (33) for storing oil, and an oil inlet pipe (34) connected to the internal cavity (33) and adapted to collect oil from the lubrication chamber (17), having a lower end (34b) which opens into the internal cavity (33), characterized in that the auxiliary reservoir (31) further comprises a degassing pipe (35) comprising an air inlet (37) disposed in the internal cavity (33), an air outlet (38) disposed in the lubrication chamber (17), the degassing pipe (35) passing through the inlet pipe (34). by said lower end (34b).Abbreviated figure: Figure 5.

Description

Title of the invention: TURBOMACHINE COMPRISING A LUBRICATION UNIT AND A SPEED REDUCER Technical field of the invention

[0001] The invention relates to the field of turbomachinery for aircraft. More particularly, the invention relates to the field of turbomachinery comprising a fan driven in rotation by a fan shaft connected to a low-pressure shaft via a mechanical speed reducer. Technical background

[0002] An aircraft turbomachine, such as a turbojet, typically comprises, from upstream to downstream in the direction of gas flow, a movable fan rotating about a longitudinal axis, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and a gas exhaust nozzle.

[0003] The fan is driven in rotation by a fan shaft connected to the rotor of the low-pressure turbine, and allows the intake of an airflow that splits into a primary airflow and a secondary airflow. The primary airflow passes through a primary channel of the turbomachine while the secondary airflow is directed towards a secondary channel surrounding the primary channel.

[0004] The primary airflow is compressed within the compressors. The compressed air is then mixed with a fuel and burned within the combustion chamber. The combustion gases pass through the turbines and then escape through the nozzle, the cross-section of which allows these gases to be accelerated to generate propulsion.

[0005] The low pressure turbine rotor is connected to the low pressure compressor rotor by a low pressure shaft and the high pressure turbine rotor is connected to the high pressure compressor rotor by a high pressure shaft.

[0006] Furthermore, in certain turbomachinery configurations, the fan shaft is connected to the low-pressure shaft by a speed reducer, which allows the fan to be driven at a rotational speed lower than the rotational speed of the low-pressure shaft. To ensure lubrication of the speed reducer, the latter is typically arranged in a lubrication chamber.

[0007] To ensure lubrication of the speed reducer within the lubrication chamber, the turbomachine further comprises a main lubrication circuit for the speed reducer. The main circuit includes a main supply pump The oil from the gearbox is connected to a main reservoir. The main pump is typically driven by the high-pressure shaft via an accessory gearbox.

[0008] During certain operating phases of the turbomachine, such as the free-running phases of the fan (known as "windmilling") during which the high-pressure shaft is barely rotated, the main pump is not primed and the main circuit does not lubricate the gearbox. In this context, the turbomachine includes an auxiliary lubrication circuit for the gearbox. The auxiliary circuit typically includes an auxiliary pump driven, for example, by the low-pressure shaft, or powered by an electric generator so that its rotational speed can be decoupled from the rotational speed of the low-pressure or high-pressure shaft. The auxiliary pump draws oil from an auxiliary oil reservoir.The auxiliary circuit thus allows the speed reducer to be lubricated even in the event of free rotation of the blower and therefore a stoppage of the main pump.

[0009] The auxiliary reservoir includes an internal oil storage cavity connected to the lubrication chamber by an oil inlet line. This oil inlet line is typically connected to the bottom of the chamber to collect the oil that falls into the chamber bottom by gravity. Thus, during standard operating phases of the turbomachine, the lubrication chamber is supplied with oil from the main lubrication circuit via the main reservoir. The oil from the lubrication chamber falls by gravity into the chamber bottom and is collected and stored in the auxiliary reservoir. During non-standard operating phases of the turbomachine, for example, when the fan is freely rotating, the main pump is not primed, and the main lubrication circuit is therefore inactive.In this case, the auxiliary pump is driven and draws oil from the auxiliary reservoir to ensure the oil supply to the lubrication chamber during such operating phases.

[0010] Although effective, this solution is not entirely satisfactory. Indeed, before the auxiliary tank is filled, part of its volume is occupied by air, which significantly reduces the available volume for oil storage. It is therefore necessary to oversize the auxiliary tank to ensure sufficient oil storage volume to lubricate the gearbox during operating phases when the auxiliary lubrication circuit is active. However, oversizing the auxiliary tank increases the overall mass of the turbomachine and makes its integration into the main turbomachine difficult.

[0011] In this context, there is a need to provide a turbomachine which makes it possible to maximize the oil storage volume in the auxiliary tank without increasing the size of the auxiliary tank. Summary of the invention

[0012] To this end, the invention proposes a turbomachine for an aircraft, extending around a longitudinal axis and comprising:

[0013] - a blower driven in rotation around the longitudinal axis by a shaft of blower,

[0014] - a low-pressure shaft connected to the blower shaft by a speed reducer mechanical,

[0015] - a lubrication chamber in which the speed reducer is located,

[0016] - a lubrication system for the speed reducer comprising a circuit main lubrication system and an auxiliary lubrication circuit connected to the lubrication chamber, the auxiliary circuit being connected to an auxiliary reservoir, the auxiliary reservoir comprising:

[0017] an internal oil storage cavity, and

[0018] an oil inlet pipe connected to the internal cavity and capable of collecting oil from the lubrication chamber, having a lower end which opens into the internal cavity.

[0019] The turbomachine is remarkable in that the auxiliary tank further comprises a degassing pipe including an air inlet disposed in the internal cavity, an air outlet disposed in the lubrication chamber, the degassing pipe passing into the inlet pipe through said lower end.

[0020] The degassing line allows air to be expelled from the auxiliary tank during its filling and thus increases the volume of the auxiliary tank available for oil storage.

[0021] According to the invention, the degassing pipe extends inside the oil inlet pipe which connects the auxiliary tank to the lubrication chamber.

[0022] Such a configuration of the auxiliary tank makes it possible to ensure the evacuation of air from the auxiliary tank without significantly altering the configuration of the turbomachine since this degassing line is integrated into the inlet pipe of the auxiliary tank.

[0023] Thanks to the invention, the available volume in the auxiliary tank for oil storage is improved.

[0024] The invention may comprise one or more of the following features, taken individually or in combination with each other:

[0025] - the auxiliary tank includes an enclosure delimiting the internal cavity, the enclosure comprising first and second portions connected by an intermediate portion, the lower end of the inlet pipe being connected to the intermediate portion, the air inlet being located in the first portion, the degassing pipe comprising a second air inlet located in the second portion, the first and second air inlets each being located at a height greater than a height of the lower end with reference to a radial axis parallel to the direction of gravity,

[0026] - the air outlet is directed outwards from the turbomachine relative to to the longitudinal axis,

[0027] - the degassing pipeline includes a tube comprising a portion of a tube a straight section extending along an axis parallel to an axis of the inlet pipe, said portion of straight tube opening onto the air outlet,

[0028] - the tube further comprises curved tube portions extending on either side of the straight section of tube in the cavity, opening respectively into the first and second air inlets,

[0029] - the first and second air inlets are arranged symmetrically, one of the other in relation to a vertical plane containing the longitudinal axis,

[0030] - the lubrication chamber is delimited by a ferrule which has a port of oil overflow located at a height higher than the height of the air inlet located in the internal cavity and lower than the height of the air outlet located in the lubrication chamber,

[0031] - the first and second portions of the enclosure are radially delimited by internal walls that lack ventilation openings,

[0032] - a housing comprising an annular inner ferrule, an annular outer ferrule and arms connecting the inner and outer shells, the lubrication chamber being located in the inner shell, the auxiliary reservoir being located outside the outer shell, and the inlet pipe being arranged in an arm located approximately at 6 o'clock in the circumferential direction relative to the longitudinal axis,

[0033] - the auxiliary tank is located in an azimuthal space between 4h and 8h in the circumferential direction with respect to the longitudinal axis. Brief description of the figures

[0034] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0035] [Fig. 1] is a schematic longitudinal cross-sectional representation of an aircraft turbomachine according to the invention,

[0036] [Fig.2] is a schematic longitudinal sectional representation of a speed reducer equipping the turbomachine of [Fig.1],

[0037] [Fig.3] is a schematic view of a lubrication system for the speed reducer of [Fig.2], comprising an auxiliary circuit and a main circuit,

[0038] [Fig.4] is a perspective view of the auxiliary tank equipping the auxiliary circuit of [Fig.3],

[0039] [Fig. 5] is a cross-sectional view of the auxiliary tank connected to the lubrication chamber when the auxiliary tank is being filled during the shutdown phases of the auxiliary circuit,

[0040] [Fig. 6] is a cross-sectional view of the auxiliary reservoir connected to the lubrication chamber when the auxiliary reservoir is filled during the shutdown phases of the auxiliary circuit,

[0041] [Fig.7] is a cross-sectional view of the auxiliary reservoir connected to the lubrication chamber during the operating phases of the auxiliary circuit. Detailed description of the invention

[0042] An example of an aircraft turbomachine 1 according to the invention is shown in [Fig. 1]. The turbomachine 1 extends around and along a longitudinal axis X.

[0043] In the present application, the terms "upstream", "downstream" are defined with respect to the direction of gas flow in the turbomachine 1 along the longitudinal axis X.

[0044] The terms "axial" and "axially" are defined with respect to the longitudinal axis X.

[0045] The terms "radial" and "radially" are defined with respect to a radial axis Z which is perpendicular to the X axis of turbomachine 1.

[0046] The terms "internal", "interior", "external", "outside", "externally" are defined with respect to the distance of the longitudinal axis X along the radial axis Z.

[0047] The turbomachine 1 comprises, from upstream to downstream, a blower 2, at least one compressor such as a low-pressure compressor 3 and a high-pressure compressor 4, a combustion chamber 5, at least one turbine such as a high-pressure turbine 6 and a low-pressure turbine 7, and a nozzle for exhausting the gases.

[0048] The blower 2 allows the intake of an airflow F which divides into a primary airflow Fl and a secondary airflow F2. The primary airflow Fl passes through a primary channel la of the turbomachine 1 while the secondary airflow F2 is directed towards a secondary channel 1b surrounding the primary channel la.

[0049] The primary airflow Fl is compressed within the low-pressure compressor 3 and then the high-pressure compressor 4. The compressed air is then mixed with a fuel and burned within the combustion chamber 5. The gases formed by the combustion pass through the high-pressure turbine 6 and the low-pressure turbine 7. The gases finally escape through the nozzle whose cross-section allows the acceleration of these gases to generate propulsion.

[0050] The blower 2 is mobile in rotation about the longitudinal axis X. The blower 2 comprises blades 2a regularly distributed around a disk centered on the longitudinal axis X.

[0051] The fan 2 is, for example, shrouded. The turbomachine 1 then comprises an annular nacelle 2b centered on the longitudinal axis X surrounding the fan 2. The nacelle 2b is, for example, supported by a fan casing 2c.

[0052] According to another example, the fan 2 is unenclosed. According to this example, the fan 2 is not surrounded by a nacelle and a fan housing.

[0053] Furthermore, the turbomachine 1 includes an inlet housing 8. The inlet housing 8 is, for example, arranged inside the nacelle 2b and the fan housing 2c. The inlet housing 8 is, for example, arranged axially between the fan 2 and the low-pressure compressor 3. The inlet housing 8 forms an inlet nozzle for the primary flow 1a. The inlet housing 8 is annular and includes, in particular, an annular outer ring 18 and an annular inner ring 19 arranged within the outer ring 18. The outer and inner rings 18, 19 are centered on the longitudinal axis X and connected by radial arms 20. One of the radial arms 20 is located at 6 o'clock by analogy to the position of the hands on a clock face.

[0054] The inner ferrule 19 may further include an oil overflow port 19a.

[0055] The primary vein is delimited downstream of the inlet spout by internal casings 110 arranged downstream of the outer ferrule 18 and the inner ferrule 19.

[0056] The secondary vein 1b is further delimited radially by the gondola 2b and an inter-vein housing 180 arranged radially between the gondola 2b and the inlet housing 8.

[0057] In addition, an inter-vein compartment is arranged radially between the secondary vein 1b and the primary vein 1a.

[0058] In the particular example of [Fig.1], the rotor of the low-pressure turbine 7 is connected to the rotor of the low-pressure compressor 3 by a low-pressure shaft 10. The rotor of the high-pressure turbine 6 is connected to the rotor of the high-pressure compressor 4 by a high-pressure shaft 9. The low-pressure shaft 10 is arranged coaxially inside the high-pressure shaft 9 and extends along the longitudinal axis X.

[0059] The low-pressure shaft 10 is guided in rotation by bearings. An intermediate bearing 10a is arranged radially between the low-pressure shaft 10 and a first bearing support 10b connected, for example, to the inner shell 19. The intermediate bearing 10a is, for example, a ball bearing.

[0060] The blower 2 is driven in rotation by a blower shaft 11. The blower shaft 11 is connected to the disk for its rotational drive. The shaft of The blower 11 is supported by a downstream bearing 11a arranged radially between the blower shaft 11 and a second support bearing 11b connected to the inner ferrule 19. The downstream bearing 11a is, for example, a ball bearing. It is arranged upstream of the intermediate bearing 10a. The downstream bearing 11a is arranged on a downstream end of the blower shaft 11.

[0061] The blower shaft 11 is also connected to the low pressure shaft 10 via a speed reducer 12. The speed reducer 12 is of the mechanical type.

[0062] As more clearly seen in [Fig.2], the speed reducer 12 comprises a solar 13, a ring 14, at least one satellite 15 which meshes with the ring 14 and the solar 13 and a satellite carrier 16.

[0063] The solar element 13 is rotationally coupled with the low-pressure shaft 10. It forms the input of the reducer 12.

[0064] The speed reducer 12 comprises a plurality of satellites 15. Each satellite 15 has a central axis Y parallel to the longitudinal axis X.

[0065] The ring 14 is annular and is arranged around the longitudinal axis X. As shown in [Fig. 1], the ring 14 is rotationally coupled with the blower shaft 11. The ring 14 includes, for example, a mounting flange 14a connected to the blower shaft 11, for example, by means of mounting rods 14b, such as screws. The ring 14 forms the output of the reducer 12.

[0066] The satellite carrier 16 is for example fixed in rotation about the longitudinal axis X. The satellite carrier 16 is connected to a fixed structure of the turbomachine 1. According to the example of [Fig.2], the satellite carrier 16 is connected to the inner shell 19, for example by means of a flexible support 1.

[0067] The speed reducer 12 is composed of gears and bearings that require lubrication. For this purpose, lubricating oil is sprayed onto the speed reducer 12. In order to protect the other components of the turbomachine 1 from this oil, the speed reducer 12 is arranged in an annular lubrication chamber 17. The lubrication chamber 17 is, for example, an upstream chamber. The lubrication chamber 17 is located inside the inner shell 19. It may include the upstream bearing 11a and the intermediate bearing 10a.

[0068] The lubrication chamber 17 has a chamber bottom F. The chamber bottom F is located at the lowest point of the lubrication chamber 17, i.e. of the inner shell 19. The lubricating oil flows by gravity into the chamber bottom F.

[0069] In order to ensure the lubrication of the speed reducer 12 in the lubrication chamber 17, the turbomachine 1 includes a lubrication system 23 for the speed reducer 12 shown in [Fig.3].

[0070] The lubrication system 23 comprises a main lubrication circuit 24 and an auxiliary lubrication circuit 25, the main and auxiliary circuits 24, 25 being connected to the lubrication chamber 17. The lubrication system 23 may further include a selective projection device 26 of the lubricating oil into the lubrication chamber 17, this selective projection device 26 being connected to the main circuit 24 and the auxiliary circuit 25.

[0071] The main circuit 24 typically includes a supply circuit 240 connecting a main reservoir 240b to the lubrication chamber 17. The supply circuit 240 includes a supply pump 240a mounted between the main reservoir 240b and the lubrication chamber 17, in particular between the main reservoir 240b and the selective spray device 26. The supply pump 240a is, for example, mechanically driven by the high-pressure shaft 9. Advantageously, the supply pump 240a is connected to the high-pressure shaft 9 via an accessory gearbox (AGB). The accessory gearbox is, for example, housed in the inter-vein compartment 1. Thus, when the high-pressure shaft 9 is driven into rotation, it primes the supply pump 240a which draws oil from the main reservoir 240b and supplies oil to the selective spraying device 26.The supply circuit 240 may further include at least one air / oil heat exchanger 240c arranged for example between the selective projection device 26 and the supply pump 240a.

[0072] The main circuit 24 further includes a return circuit 241 connecting the lubrication chamber 17 to the main reservoir 240b, for example, via the overflow port 19a. The return circuit 241 includes a recovery pump 241a, which is advantageously arranged in the inter-vein compartment 1. The recovery pump 241a is connected to the main reservoir 240b and to the lubrication chamber 17. In particular, the recovery pump 241a has an inlet hydraulic line 242a connected to the lubrication chamber 17 and an outlet hydraulic line 242b connected to the main reservoir 240b.

[0073] In some cases, the high-pressure shaft 9 is not driven to rotate or is driven at a rotational speed insufficient to drive the feed pump 240a. For example, when the blower 2 is in free rotation (or self-rotating, also known as "windmilling"), or during the start-up or shutdown phases of the turbomachine 1, the feed pump 240a is not primed and is no longer able to supply oil to the selective spraying device 26. The speed reducer 12 is then no longer lubricated by the main circuit 24. Lubrication of the speed reducer 12 is ensured in such a case by the auxiliary circuit 25.

[0074] The auxiliary circuit 25 is a closed lubrication circuit for the lubrication chamber 17. It includes an auxiliary pump 28 connected to an auxiliary reservoir 31 and to the lubrication chamber 17, in particular to the selective projection device 26.

[0075] The auxiliary reservoir 31 is located outside the lubrication chamber 17. Preferably, the auxiliary reservoir 31 is located outside the outer shell 18. Preferably, the auxiliary reservoir 31 is arranged in the inter-flow compartment 1a. Since the auxiliary reservoir 31 is located outside the primary flow 1a, the auxiliary reservoir 31 can have a large internal volume without impacting the aerodynamic performance of the turbomachine 1. A large volume of oil can thus be stored.

[0076] The auxiliary reservoir 31 is located in the lower part of the inter-vein compartment, in an azimuthal space for example between 4 o'clock and 8 o'clock in the circumferential direction with respect to the longitudinal axis X. This allows the oil to flow by gravity into the auxiliary reservoir 31.

[0077] With reference to Figures 3 to 7, the auxiliary tank 31 may have a generally curved or arched shape. This facilitates the attachment of the auxiliary tank 31 to one of the housings of the turbomachine 1. The auxiliary tank 31 thus extends circumferentially or over an angular sector between a first circumferential end 31a and a second circumferential end 31b.

[0078] The auxiliary tank 31 comprises an enclosure 32 that delimits an internal oil storage cavity 33. The enclosure 32 extends between the first and second circumferential ends 31a, 31b. The enclosure 32 preferably has a general U-shape. It preferably comprises a first portion 32a and a second portion 32b connected by an intermediate portion 32c located between the first and second circumferential ends 31a, 31b. The intermediate portion 32c is axially delimited by lateral walls 32d extending radially from an internal wall 32e of the intermediate portion 32c. The first and second portions 32a, 32b are radially delimited by internal walls 32f extending circumferentially from the lateral walls 32d. The internal walls 32f are solid. They are therefore devoid of ventilation openings.

[0079] The internal storage cavity 33 extends circumferentially between the first and second circumferential ends 31a, 31b of the reservoir 31. The internal storage cavity 33 has a maximum storage volume located in the first and second portions 32a, 32b and an intermediate storage volume located in the intermediate portion 32c. The maximum storage volume is greater than the intermediate storage volume. Thus, when the auxiliary reservoir 31 is filled, the oil level in the first and second portions 32a, 32b is higher than the oil level in the intermediate portion 32c.

[0080] The auxiliary reservoir 31 further includes an oil inlet pipe 34 which is connected to the internal cavity 33 and which is suitable for collecting oil from the lubrication chamber 17. The inlet pipe 34 is preferably located on the portion Intermediate 32c. The inlet pipe 34 is, for example, located between 5 and 7 o'clock, analogous to the position of the hands on a clock face. The oil can therefore flow by gravity within the inlet pipe 34 and fill the auxiliary reservoir 31. The inlet pipe 34 is advantageously arranged in the arm 20 located at 6 o'clock.

[0081] The inlet pipe 34 is preferably annular and has an axis Al which extends radially with respect to the longitudinal axis X. The inlet pipe 34 has two ends 34a, 34b opposite along its axis AL. With reference to [Fig.5] for example, each end 34a, 34b is open. An upper end 34a opens into the radial arm 20 towards the lubrication chamber 17, and a lower end 34b opens into the internal cavity 33. The upper end 34a can be sealed into an internal channel of the arm 20 which opens into the lubrication chamber 17, this internal channel being shaped to collect oil from the bottom of the lubrication chamber 17. Alternatively, the inlet channel 34 can extend the entire height of the arm 20 such that the upper end 34a opens directly into the lubrication chamber 17, being shaped to collect oil from the bottom of the chamber.

[0082] The auxiliary tank 31 further includes a degassing line 35. The degassing line 35 includes a tube 36, an air inlet 37 and an air outlet 38 connected together by the tube 36.

[0083] The air outlet 38 is located in the lubrication chamber 17. It is preferably located in the bottom of the chamber F. The air outlet 38 is directed outwards from the turbomachine 1 with reference to the longitudinal axis X. Such an orientation of the air outlet 38 helps to limit the risk of contamination of the degassing line 35 by oil flowing by gravity into the lubrication chamber 17 from the speed reducer 12 located above the air outlet 38.

[0084] Preferably, the degassing pipe 35 includes a second air inlet 37' which is connected to the air outlet 38 by the tube 36.

[0085] Each air inlet 37, 37' is located in the internal cavity 33 of the auxiliary tank 31. Each air inlet 37, 37' is oriented towards the interior of the turbomachine 1 with reference to the longitudinal axis X of the turbomachine 1. Thus, each air inlet 37, 37' is oriented in a direction opposite to the air outlet 38.

[0086] Advantageously, the air inlet 37 is located in the internal cavity 33 delimited by the first portion 32a of the enclosure 32 and the second air inlet 37' is located in the internal cavity 33 delimited by the second portion 32b of the enclosure 32.

[0087] According to an advantageous embodiment, each air inlet 37, 37' is offset with respect to the axis Al of the inlet pipe 34. This prevents contamination of the air inlets 37, 37' by oil flowing into the auxiliary reservoir 31.

[0088] Preferably, the first and second air inlets 37, 37' are each located at a height hl greater than a height h2 of the lower end 34b of the inlet pipe 34, the heights hl, h2 being measured along the radial axis Z which is parallel to the direction of gravity.

[0089] Advantageously, the overflow port 19a is located at a height h3 higher than the height hl of each air inlet 37, 37' disposed in the internal cavity 33 and lower than the height h4 of the air outlet 38 disposed in the lubrication enclosure 17.

[0090] Advantageously, the air inlets 37, 37' are arranged symmetrically with respect to a vertical plane containing the longitudinal axis X.

[0091] The tube 36 passes into the inlet pipe 34 through the lower end 34b of the inlet pipe 34.

[0092] The tube 36 advantageously has a straight tube portion 36a extending along an axis parallel or substantially parallel to the axis Al of the inlet pipe 34. The straight tube portion 36a extends coaxially within the inlet pipe 34. The straight tube portion 36a passes through the lower and upper ends 34b, 34a of the inlet pipe 34. This straight tube portion 36a opens onto the air outlet 38.

[0093] The tube 36 further comprises curved tube portions 36b, 36c extending on either side of the straight tube portion 36a. Each curved tube portion 36b, 36c extends respectively into the first and second portions 32a, 32b of the enclosure 32 and opens respectively into the first and second air inlets 37, 37'.

[0094] Preferably, the degassing pipe 35 has an external diameter smaller than an internal diameter of the inlet pipe 34. For example, the internal diameter of the inlet pipe 34 is between two and ten times greater than the external diameter of the degassing pipe 35.

[0095] The degassing pipe 35 can be held in position within the auxiliary tank 31 by means of fastening clips mounted on the internal walls of the tank. Alternatively, the degassing pipe 35 can be welded to the internal walls of the tank, or even formed entirely with the internal walls, for example, in the form of relatively thin and / or narrow double-wall sections so as not to reduce the effective oil storage volume. The degassing pipe 35 can also form hollow ribs on the internal walls of the tank 31, for example, having an air passage cross-section forming an arc or a U-shape, which serve to stiffen the structure of the auxiliary tank.

[0096] The oil flows by gravity into the lubrication chamber 17 and into the internal cavity 33 of the auxiliary reservoir 31 via its inlet pipe 34. The oil is stored in the auxiliary reservoir 31. Thanks to the degassing pipe 35 integrated into the auxiliary reservoir 31, the maximum oil storage volume of the auxiliary reservoir 31 is optimized without increasing the overall size of the auxiliary reservoir 31 and without impacting the configuration of the turbomachine 1. A larger volume of oil can therefore be contained in this auxiliary reservoir 31. This ensures reliable lubrication of the gearbox 12 regardless of the operating phases of the turbomachine 1.

[0097] The auxiliary tank 31 may further include fastening elements 39 mounted on the tank housing 32. Each fastening element 39 includes, for example, a fastening tab 39a having at least one opening 39b for the passage of fastening rods to one of the housings of the turbomachine 1.

[0098] The auxiliary pump 28 is driven, for example, by an electric motor 29. The auxiliary pump 28 and the electric motor 29 are, for example, arranged in the inter-vein compartment 1. The electric motor 29 is supplied with electrical energy by an electric generator (not shown), for example, located in the lubrication chamber 17. The electric generator provides electrical energy to the electric motor 29 from mechanical energy. The electric generator, for example, draws mechanical energy from the blower shaft 11. For example, the electric generator is connected to the blower shaft 11 via gears 30.

[0099] The electric motor is, for example, controlled by a control unit 290. The control unit 290 allows the speed of the auxiliary pump 28 to be modulated via the electric motor. The control unit is, for example, a FADEC (for "Full Automatic Digital Engine Control").

[0100] According to another example, the auxiliary pump 28 is driven by the low-pressure shaft 10.

[0101] The selective projection device 26 includes, for example, a selection member 27' and at least one nozzle 27 which is arranged in the lubrication chamber 17. The selection member 27' is, for example, a selection valve connected to the main and auxiliary circuits 24, 25.

[0102] The nozzle 27 allows the lubricating oil to be projected into the lubrication chamber 17. The selective projection device 26 may advantageously include two nozzles 27, a first nozzle projecting the lubricating oil onto the speed reducer 12. The nozzles are connected to the selection member 27' and are supplied with lubricating oil by one of the circuits 24, 25 depending on the position of the selection valve.

[0103] The operation of the main and auxiliary circuits 24, 25 will now be described with reference to figures 5 to 7.

[0104] The turbomachine 1 is initially at a standstill. The main and auxiliary circuits 24, 25 are therefore at a standstill. In this first phase, the auxiliary tank 31 contains air and is either free of oil or also contains oil from a previous flight.

[0105] With reference to [Fig. 5], in a first phase of nominal operation of the turbomachine 1, the auxiliary circuit 25 is inactive, i.e., the auxiliary pump 28 is inactive. The main circuit 24 is active, i.e., the feed pump 240a is active and draws oil from the main reservoir 240b. The oil is conveyed to the lubrication chamber 17 via the main circuit 24. In this first phase, the lubricating oil flows by gravity into the bottom of the chamber F and into the auxiliary reservoir 31. This oil is stored in the auxiliary reservoir 31. Air is simultaneously vented through the degassing line 35 via the air inlets 37, 37'. Thanks to this air evacuation which allows the internal cavity 33 to be filled with oil, the volume available in the auxiliary tank 31 for oil storage is maximized.

[0106] With reference to [Fig. 6], the recovery pump 241a (illustrated in [Fig. 3]), fluidly connected to the overflow port 19a of the lubrication chamber 17, is also active, for example. When the volume of oil in the auxiliary reservoir 31 exceeds its maximum volume, the oil accumulates in the degassing line 35 and overflows into the bottom of the chamber F. The oil is discharged through the overflow port 19a. The recovery pump 241a then draws oil from this overflow port 19a and allows the oil to circulate in the return circuit 241 of the main circuit 24 to supply oil to the main reservoir 240b.

[0107] With reference to [Fig. 7], in a second phase of operation of the turbomachine 1, for example, in the event of free rotation of the fan 2 and a stoppage or insufficient rotational speed of the high-pressure shaft 10, the pressure in the main circuit 24 decreases such that the selector 27' is supplied by the auxiliary circuit 25, in which the oil pressure is higher. Indeed, the feed pump 240a is then unprimed or provides insufficient oil pressure for the required flow rate, while the auxiliary circuit 25 is active. The auxiliary pump 28 draws oil from the auxiliary reservoir 31 and allows its circulation in the auxiliary circuit 25 for the lubrication of the gearbox 12 in the lubrication chamber 17.The oil present in the degassing line 35 can also be drawn off by the auxiliary pump 28 or remain at least partially trapped in the degassing line 35, depending on the level of oil consumption during this second phase of operation. When the oil level drops in the auxiliary reservoir 31. Because the oil flow rate drawn from reservoir 31 by the auxiliary pump 28 is at least temporarily greater than the oil flow rate entering reservoir 31 via the inlet pipe 34, air is drawn into the vent line 35 through its air outlet 38, which then becomes an air inlet for the reservoir. This allows air and / or oil present in the vent line 35 to be drawn towards the chamber 32 of reservoir 31, thus lowering the oil level in each of the first and second sections 32a, 32b of the chamber 32 in order to supply oil to the auxiliary pump 28.

[0108] It follows from the above that, thanks to the invention, it is possible to increase the available volume of the auxiliary tank 31 for oil storage without increasing the size of the auxiliary tank 31.

[0109] Thanks to the invention, it is possible to guarantee a sufficient volume of oil in the auxiliary reservoir 31 for the lubrication of the speed reducer 12 in the lubrication chamber 17 in the event of a stoppage of the supply pump 240a of the main circuit 24, for example in the event of free rotation of the blower 2.

Claims

Demands

1. Turbomachine (1) for an aircraft, extending about a longitudinal axis (X) and comprising: - a fan (2) driven in rotation about the longitudinal axis (X) by a fan shaft (11), - a low-pressure shaft (10) connected to the fan shaft (2) by a mechanical speed reducer (12), - a lubrication chamber (17) in which the speed reducer (12) is located, - a lubrication system (23) for the speed reducer comprising a main lubrication circuit (24) and an auxiliary lubrication circuit (25) connected to the lubrication chamber (17), the auxiliary circuit (25) being connected to an auxiliary tank (31), the auxiliary tank (31) comprising: an internal oil storage cavity (33), and an oil inlet pipe (34) connected to the internal cavity (33) and capable of collecting oil from the lubrication chamber (17),having a lower end (34b) which opens into the internal cavity (33), characterized in that the auxiliary reservoir (31) further comprises a degassing pipe (35) including an air inlet (37) disposed in the internal cavity (33), an air outlet (38) disposed in the lubrication chamber (17), the degassing pipe (35) passing into the inlet pipe (34) through said lower end (34b).

2. Turbomachine according to the preceding claim, characterized in that the auxiliary tank (31) comprises an enclosure (32) delimiting the internal cavity (33), the enclosure (32) comprising first and second portions (32a, 32b) connected by an intermediate portion (32c), the lower end (34b) of the inlet pipe (34) being connected to the intermediate portion (32c), the air inlet (37) being located in the first portion (32a), the degassing pipe (35) comprising a second air inlet (37') located in the second portion (32b), the first and second air inlets (37, 37') each being located at a height (hl) greater than a height (h2) of the lower end (34b) with reference to a radial axis (Z) parallel to the direction of gravity.

3. Turbomachine according to any one of the preceding claims, characterized in that the air outlet (38) is oriented outwards from the turbomachine (1) relative to the longitudinal axis (X).

4. Turbomachine according to any one of the preceding claims, characterized in that the degassing pipe (35) comprises a tube (36) comprising a straight tube portion (36a) extending along an axis parallel to an axis (Al) of the inlet pipe (34), said straight tube portion (36a) opening onto the air outlet (38).

5. Turbomachine according to the preceding claim in combination with claim 2, characterized in that the tube (36) further comprises curved tube portions (36b, 36c) extending on either side of the straight tube portion (36a) in the cavity (33) and opening respectively into the first and second air inlets (37, 37').

6. Turbomachine according to claim 2 or any of the preceding claims in combination with claim 2, characterized in that the first and second air inlets (37, 37') are arranged symmetrically with respect to a vertical plane containing the longitudinal axis (X).

7. Turbomachine according to any one of the preceding claims, characterized in that the lubrication chamber (17) is delimited by a shell (19) which has an oil overflow port (19a) located at a height (h3) higher than a height (hl) of the air inlet (37) disposed in the internal cavity (33) and lower than a height (h4) of the air outlet (38) disposed in the lubrication chamber (17).

8. Turbomachine according to claim 2 or any of the preceding claims in combination with claim 2, characterized in that the first and second portions (32a, 32b) of the enclosure (32) are radially delimited by internal walls (32f) which are devoid of ventilation orifice.

9. Turbomachine according to any one of the preceding claims, characterized in that it comprises a housing (8) including an annular inner shell (19), an annular outer shell (18), and arms (20) connecting the inner and outer shells (19, 18), the lubrication chamber (17) being located in the inner shell

10. (19), the auxiliary reservoir (31) being located outside the outer shell (18), and the inlet pipe (34) being arranged in an arm (20) located approximately at 6 o'clock in the circumferential direction with respect to the longitudinal axis (X). Turbomachine according to any one of the preceding claims, characterized in that the auxiliary tank (31) is located in an azimuthal space between 4h and 8h in the circumferential direction with respect to the longitudinal axis (X).

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