Turbine engine comprising a lubrication chamber and a speed reducer

Abstract

The invention relates to a turbine engine comprising: - a lubrication chamber (17) in which a speed reducer (12) is located; and - a main lubrication circuit and an auxiliary lubrication circuit, which are connected to the lubrication chamber (17), the auxiliary circuit being connected to an auxiliary tank (31) comprising an internal oil storage cavity (33) and an oil inlet pipe (34) that is connected to the internal cavity (33) and that is capable of collecting oil coming from the lubrication chamber (17), the oil inlet pipe having a lower end (34b) that opens into the internal cavity (33). The turbine engine is characterised in that the auxiliary tank (31) further comprises a degassing pipe (35) comprising an air inlet (37) arranged in the internal cavity (33) and an air outlet (38) arranged in the lubrication chamber (17), the degassing pipe (35) passing through the inlet pipe (34) via the lower end (34b).

Description

[0001] DESCRIPTION

[0002] TITLE: TURBOMACHINE COMPRISING A LUBRICATION UNIT AND A SPEED REDUCER

[0003] Technical field of the invention

[0004] 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.

[0005] Technical background

[0006] 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.

[0007] 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 duct of the turbomachine, while the secondary airflow is directed towards a secondary duct surrounding the primary duct.

[0008] The primary airflow is compressed within the compressors. The compressed air is then mixed with fuel and burned in the combustion chamber. The combustion gases pass through the turbines and then escape through the nozzle, whose cross-section allows these gases to be accelerated to generate propulsion. The rotor of the low-pressure turbine is connected to the rotor of the low-pressure compressor by a low-pressure shaft, and the rotor of the high-pressure turbine is connected to the rotor of the high-pressure compressor by a high-pressure shaft. Furthermore, in some turbomachine 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 that of the low-pressure shaft. To ensure lubrication of the speed reducer, it is typically housed in a lubrication chamber.

[0009] To ensure lubrication of the gearbox within the lubrication chamber, the turbomachine also includes a main gearbox lubrication circuit. This main circuit comprises a main oil supply pump for the gearbox connected to a main reservoir. The main pump is typically driven by the high-pressure shaft via an accessory gearbox.

[0010] During certain operating phases of the turbomachine, such as the free-running phases of the fan (known as "windmilling"), when the high-pressure shaft is barely rotating, the main pump is not primed and the main circuit does not lubricate the gearbox. In this case, 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 gearbox to be lubricated even when the fan is freely rotating and the main pump is therefore stopped.

[0011] 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 the oil available in the auxiliary reservoir to ensure the oil supply to the lubrication chamber during such operating phases.

[0012] Although effective, this solution is not entirely satisfactory. Before the auxiliary tank is filled, a portion of its volume is occupied by air, significantly reducing the available volume for oil storage. Therefore, it is necessary to oversize the auxiliary tank to ensure sufficient oil storage volume for lubricating 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.

[0013] In this context, there is a need to provide a turbomachine that maximizes the oil storage volume in the auxiliary tank without increasing the size of the auxiliary tank.

[0014] Summary of the invention

[0015] To this end, the invention proposes a turbomachine for an aircraft, extending around a longitudinal axis and comprising:

[0016] - a blower driven in rotation around the longitudinal axis by a blower shaft, - a low-pressure shaft connected to the blower shaft by a mechanical speed reducer,

[0017] - a lubrication chamber in which the speed reducer is located,

[0018] - a speed reducer lubrication system comprising a main lubrication circuit and an auxiliary lubrication circuit connected to the lubrication chamber, the auxiliary circuit being connected to an auxiliary reservoir, the auxiliary reservoir comprising: an internal oil storage cavity, and an oil inlet pipe connected to the internal cavity and suitable for 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 includes a degassing pipe comprising an air inlet disposed in the internal cavity, an air outlet disposed in the lubrication chamber, the degassing pipe passing into the inlet pipe by said lower end.

[0020] The degassing line allows air to be expelled from the auxiliary tank during its filling, thus increasing 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. The invention may include one or more of the following features, taken individually or in combination:

[0024] - the auxiliary tank comprises 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,

[0025] - the air outlet is directed outwards from the turbomachine relative to the longitudinal axis,

[0026] - the degassing pipeline comprises a tube including a straight tube portion extending along an axis parallel to an axis of the inlet pipeline, said straight tube portion opening onto the air outlet,

[0027] - the tube further comprises curved tube sections extending on either side of the straight tube section in the cavity and opening respectively into the first and second air inlets,

[0028] - the first and second air inlets are arranged symmetrically with respect to a vertical plane containing the longitudinal axis,

[0029] - the lubrication chamber is delimited by a shell which has an oil overflow port 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,

[0030] - the first and second sections of the enclosure are radially delimited by internal walls which lack ventilation openings,

[0031] - a casing comprising an inner annular shell, an outer annular shell 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 disposed in an arm located approximately at 6 o'clock in the circumferential direction with respect to the longitudinal axis,

[0032] - the auxiliary tank is located in an azimuthal space between 4h and 8h in the circumferential direction relative to the longitudinal axis.

[0033] 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: Figure 1 is a schematic longitudinal cross-sectional representation of an aircraft turbomachine according to the invention; Figure 2 is a schematic longitudinal cross-sectional representation of a speed reducer equipping the turbomachine of Figure 1; Figure 3 is a schematic view of a lubrication system for the speed reducer of Figure 2, comprising an auxiliary circuit and a main circuit; Figure 4 is a perspective view of the auxiliary tank equipping the auxiliary circuit of Figure 3; Figure 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.Figure 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; Figure 7 is a cross-sectional view of the auxiliary reservoir connected to the lubrication chamber during the operating phases of the auxiliary circuit.

[0035] Detailed description of the invention An example of an aircraft turbomachine 1 according to the invention is shown in Figure 1. The turbomachine 1 extends around and along a longitudinal axis X.

[0036] In this application, the terms "upstream" and "downstream" are defined in relation to the direction of gas flow in the turbomachine 1 along the longitudinal axis X.

[0037] The terms "axial" and "axially" are defined with respect to the longitudinal axis X.

[0038] The terms "radial", "radially" are defined with respect to a radial axis Z which is perpendicular to the X axis of the turbomachine 1.

[0039] The terms "internal", "interior", "external", "exterior",

[0040] "Externally" are defined with respect to the distance from the longitudinal axis X along the radial axis Z.

[0041] 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.

[0042] The blower 2 allows the intake of an airflow F which divides into a primary airflow F1 and a secondary airflow F2. The primary airflow F1 passes through a primary channel 1a of the turbomachine 1 while the secondary airflow F2 is directed towards a secondary channel 1b surrounding the primary channel 1a.

[0043] The primary airflow F1 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 low-pressure turbine 7. The gases finally escape through the nozzle whose cross-section allows the acceleration of these gases to generate propulsion.

[0044] The fan 2 is free to rotate about the longitudinal axis X. The fan 2 comprises blades 2a evenly distributed around a disk centered on the longitudinal axis X. 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.

[0045] In another example, the fan 2 is unshrouded. In this example, the fan 2 is not enclosed by a nacelle and a fan housing. 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 ferrule 18 and an annular inner ferrule 19 arranged in the outer ferrule 18. The outer and inner ferrules 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 the dial of a clock.

[0046] The inner ferrule 19 may further include an oil overflow port 19a.

[0047] The primary vein 1a is delimited downstream of the inlet spout by internal casings 110 arranged downstream of the external ferrule 18 and the internal ferrule 19. The secondary vein 1b is further delimited radially by the nacelle 2b and an inter-vein casing 180 arranged radially between the nacelle 2b and the inlet casing 8.

[0048] In addition, an inter-vein compartment 1c is arranged radially between the secondary vein 1b and the primary vein 1a.

[0049] In the specific example shown in Figure 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. The low-pressure shaft 10 is guided in rotation by bearings. An intermediate bearing 10a, for example, is arranged radially between the low-pressure shaft 10 and a first bearing support 10b, which is connected, for example, to the inner shell 19. The intermediate bearing 10a is, for example, a ball bearing.

[0050] 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 blower shaft 11 is supported by a downstream bearing 11a arranged radially between the blower shaft 11 and a second bearing support 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.

[0051] 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.

[0052] As more clearly seen in Figure 2, the speed reducer 12 includes 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.

[0053] The solar element 13 is rotationally coupled with the low-pressure shaft 10. It forms the input of the reducer 12.

[0054] The speed reducer 12 comprises a plurality of satellites 15. Each satellite 15 has a central axis Y parallel to the longitudinal axis X.

[0055] The ring 14 is annular and arranged around the longitudinal axis X. As shown in Figure 1, the ring 14 is rotationally coupled to 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.

[0056] The planet carrier 16 is, for example, fixed in rotation about the longitudinal axis X. The planet carrier 16 is connected to a fixed structure of the turbomachine 1. As shown in Figure 2, the planet carrier 16 is connected to the inner shell 19, for example, by means of a flexible support 11c. The gearbox 12 consists of gears and bearings that require lubrication. For this purpose, lubricating oil is sprayed onto the gearbox 12. In order to protect the other components of the turbomachine 1 from this oil, the gearbox 12 is arranged in an annular lubrication chamber 17. The lubrication chamber 17 is, for example, an upstream chamber. The lubrication enclosure 17 is located inside the inner shell 19. It may include the upstream bearing 11a and the intermediate bearing 10a.

[0057] 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.

[0058] 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 Figure 3.

[0059] The lubrication system 23 includes 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 for the lubricating oil in the lubrication chamber 17, this selective projection device 26 being connected to the main circuit 24 and the auxiliary circuit 25.

[0060] 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, specifically 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 1c. 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 also include at least one air / oil exchanger 240c arranged for example between the selective projection device 26 and the supply pump 240a.

[0061] 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 1c. 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.

[0062] In some cases, the high-pressure shaft 9 is not driven to rotate or is driven at an insufficient rotational speed 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 spray device 26. The speed reducer 12 is then no longer lubricated by the main circuit 24. In such a case, lubrication of the speed reducer 12 is ensured by the auxiliary circuit 25.

[0063] The auxiliary circuit 25 is a closed-loop lubrication system for the lubrication chamber 17. It includes an auxiliary pump 28 connected to an auxiliary reservoir 31 and to the lubrication chamber 17, specifically to the selective spray device 26. 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 1c. Because the auxiliary reservoir 31 is located outside the primary flow 1a, it can have a large internal volume without impacting the aerodynamic performance of the turbomachine 1. A large volume of oil can thus be stored.

[0064] The auxiliary reservoir 31 is located in the lower part of the intervein compartment 1 c, in an azimuthal space between, for example, 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.

[0065] 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.

[0066] The auxiliary tank 31 includes an enclosure 32 that defines 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.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.

[0067] The auxiliary reservoir 31 further includes an oil inlet pipe 34 connected to the internal cavity 33, which is suitable for collecting oil from the lubrication chamber 17. The inlet pipe 34 is preferably located on the intermediate portion 32c. For example, the inlet pipe 34 is situated between 5 and 7 o'clock, analogous to the position of the hands on a clock face. The oil can thus flow by gravity through the inlet pipe 34 and fill the auxiliary reservoir 31. The inlet pipe 34 is advantageously located in the arm 20 at 6 o'clock.

[0068] The inlet pipe 34 is preferably annular and has an axis A1 that extends radially with respect to the longitudinal axis X. The inlet pipe 34 has two ends 34a, 34b opposite along its axis A1. Referring to Figure 5, for example, each end 34a, 34b is open. An upper end 34a opens into the radial arm 20 in the direction of 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 the oil from the bottom of the lubrication chamber 17. Alternatively, the inlet channel 34 can extend over the entire height of the arm 20 so that the upper end 34a opens directly into the lubrication chamber 17, being shaped to collect the oil from the bottom of the chamber.

[0069] The auxiliary tank 31 further includes a degassing pipe 35. The degassing pipe 35 includes a tube 36, an air inlet 37 and an air outlet 38 connected together by the tube 36.

[0070] The air outlet 38 is located in the lubrication chamber 17. Preferably, it is 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. This 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.

[0071] Preferably, the degassing pipe 35 includes a second air inlet 37' which is connected to the air outlet 38 by the tube 36.

[0072] 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.

[0073] 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.

[0074] According to an advantageous embodiment, each air inlet 37, 37' is offset from the axis A1 of the inlet pipe 34. This prevents contamination of the air inlets 37, 37' by oil flowing into the auxiliary tank 31.

[0075] Preferably, the first and second air inlets 37, 37' are each located at a height h1 greater than a height h2 from the lower end 34b of the inlet duct 34, the heights h1, h2 being measured along the radial axis Z which is parallel to the direction of gravity. Advantageously, the overflow port 19a is located at a height h3 higher than the height h1 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 chamber 17.

[0076] Advantageously, the air inlets 37, 37' are arranged symmetrically with respect to a vertical plane containing the longitudinal axis X.

[0077] The tube 36 passes into the inlet pipe 34 through the lower end 34b of the inlet pipe 34.

[0078] The tube 36 advantageously has a straight tube portion 36a extending along an axis parallel or substantially parallel to the axis A1 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 into the air outlet 38.

[0079] 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'.

[0080] Preferably, the degassing pipe 35 has an external diameter smaller than the 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.

[0081] The degassing pipe 35 can be held in position within the auxiliary tank 31 by means of fixing clips mounted on the tank's internal walls. Alternatively, the degassing pipe 35 can be welded to the tank's internal walls, or even formed as an integral part of the internal walls, for example, as relatively thin and / or narrow double-walled sections to avoid reducing the effective oil storage volume. The degassing pipe 35 can also form hollow ribs on the internal walls of the tank 31, for example, with an air passage cross-section forming an arc or a U-shape, which serve to stiffen the structure of the auxiliary tank.

[0082] 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 its overall size or 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.

[0083] 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 lug 39a having at least one opening 39b for the passage of fastening rods to one of the housings of the turbomachine 1.

[0084] The auxiliary pump 28 is driven, for example, by an electric motor 29. The auxiliary pump 28 and the electric motor 29 are arranged, for example, in the inter-vein compartment 1c. 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. The electric motor is, for example, controlled by a control unit 290. The control unit 290 modulates the speed of the auxiliary pump 28 via the electric motor. The control unit is, for example, a FADEC (Full Automatic Digital Engine Control).

[0085] According to another example, the auxiliary pump 28 is driven by the low-pressure shaft 10.

[0086] 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.

[0087] 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.

[0088] The operation of the main and auxiliary circuits 24, 25 will now be described with reference to figures 5 to 7.

[0089] Turbomachine 1 is initially at a standstill. Therefore, the main and auxiliary circuits 24 and 25 are also at a standstill. In this initial phase, the auxiliary tank 31 contains air and is either free of oil or also contains oil from a previous flight.

[0090] Referring to Figure 5, in the first phase of nominal operation of the turbomachine 1, the auxiliary circuit 25 is inactive, meaning that the auxiliary pump 28 is inactive. The main circuit 24 is active, meaning that 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 to 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.

[0091] Referring to Figure 6, the recovery pump 241a (illustrated in Figure 3), which is 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.

[0092] Referring to Figure 7, in a second phase of operation of the turbomachine 1, for example, if the fan 2 is rotating freely and the high-pressure shaft 10 is stopped or its rotation speed is insufficient, 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. This is because the feed pump 240a is then primed 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 circulates it through the auxiliary circuit 25 to lubricate the gearbox 12 in the lubrication chamber 17.The oil present in the degassing line 35 can also be drawn 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 the reservoir 31 by the auxiliary pump 28 is at least temporarily greater than the oil flow rate entering the reservoir 31 via the inlet pipe 34, air is drawn into the degassing line 35 via its air outlet 38, which then becomes an air inlet for the reservoir. This allows air and / or oil present in the degassing line 35 to be drawn towards the enclosure 32 of the reservoir 31, thus allowing a drop in the oil level in each of the first and second portions 32a, 32b of the enclosure 32 in order to supply oil to the auxiliary pump 28.

[0093] 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.

[0094] 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 blower (2) driven in rotation around the longitudinal axis (X) by a blower shaft (11), - a low-pressure shaft (10) connected to the blower 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 reservoir (31), the auxiliary reservoir (31) comprising: an internal oil storage cavity (33), 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) opening 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 pipe entry (34) by 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 (h1) 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 directed 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) including a straight tube portion (36a) extending along an axis parallel to an axis (A1) 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 ferrule (19) which has an oil overflow port (19a) located at a height (h3) higher than a height (h1) 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 enclosure (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 casing (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 (19), the auxiliary tank (31) being located outside the outer shell (18), and the inlet pipe (34) being disposed in an arm (20) located substantially at 6 o'clock in the circumferential direction with respect to the longitudinal axis (X).

10. 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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