Casing for an aircraft turbine engine

Abstract

The invention relates to a casing (8) comprising: - an inner annular shroud (19) that internally defines a lubrication chamber (17) and an outer annular shroud (18); - an arm that extends radially between the inner and outer annular shrouds (19, 18), the arm comprising: an inner cavity (200) provided with a first compartment (21a) that opens into the lubrication chamber (17) through an oil inlet (200a) provided in the inner shroud (19) and a second compartment (21b), the second compartment (21b) being separated from the lubrication chamber (17) by a cover (22) that extends longitudinally inside the lubrication chamber (17) from the second annular edge (19b) of the inner annular shroud (19) to the oil inlet (200a), wherein the oil inlet (200a) is circumferentially bounded by first and second walls (23a, 23b) which extend radially from the inner shroud (19) on either side of the oil inlet (200a).

Description

[0001] DESCRIPTION

[0002] TITLE: CASING FOR AN AIRCRAFT TURBOMACHINE

[0003] Technical field of the invention

[0004] The invention relates to the field of casings for aircraft turbomachines.

[0005] More particularly, the invention falls within the field of casings defining a lubrication enclosure, for turbomachines comprising a lubrication system for a speed reducer, comprising main and auxiliary lubrication circuits.

[0006] Technical background

[0007] The state of the art is illustrated by document US-A1-2006 / 042223.

[0008] An aircraft turbomachine typically comprises, from upstream to downstream in the direction of gas flow, a fan rotating about a longitudinal axis, a low-pressure compressor and a high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine and a gas exhaust nozzle.

[0009] The blower allows the suction of an air flow divided into a primary flow and a secondary flow. The primary flow passes through a primary vein of the turbomachine while the secondary flow is directed towards a secondary vein surrounding the primary vein.

[0010] The turbomachine further comprises an inlet casing centered on the longitudinal axis and defining the inlet of the primary flow path. The inlet casing comprises an annular inner shell surrounded by an annular outer shell connected by radial arms.

[0011] The primary flow is compressed downstream within the compressors. The compressed air is then mixed with fuel and burned within the combustion chamber. The gases from the combustion pass through the turbines and then escape through the nozzle, the cross-section of which allows the gases to be accelerated to generate propulsion.

[0012] 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, the fan is rotated by a fan shaft that 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. The speed reducer is typically arranged in a lubrication chamber for lubricating the speed reducer. The lubrication chamber is typically arranged inside the inner shell.

[0013] To ensure lubrication of the speed reducer in the lubrication enclosure, the turbomachine further comprises a main lubrication circuit for the reducer connected to the lubrication enclosure. The main circuit comprises a reducer oil supply pump connected to a main oil reservoir. The oil supply pump is typically rotated by the high-pressure shaft via an accessory drive gearbox.

[0014] During certain operating phases of the turbomachine, such as the free rotation phases of the fan (known as "windmilling") during which the fan shaft is rotated, thus driving the low-pressure shaft, the rotation speed of the high-pressure shaft is insufficient to drive the feed pump at a speed sufficient to provide the flow rate necessary for lubricating the reducer. However, it is necessary to ensure lubrication of the speed reducer even during these operating phases of the turbomachine.

[0015] In this context, the turbomachine includes an auxiliary circuit for lubricating the reducer. The auxiliary circuit typically includes an auxiliary pump powered by an electric generator, for example, or driven by the low-pressure shaft, which allows the auxiliary pump to be primed even when the fan is rotating freely and the high-pressure shaft is rotating at a low speed.

[0016] In order to supply the auxiliary circuit with oil, document FR-A1 -3 075 875 proposes recovering the oil flowing by gravity into the bottom of the enclosure. For this purpose, one of the radial arms located at 6 o'clock has an internal cavity opening into the enclosure through an oil inlet. The arm also has a first oil outlet connected to the main circuit by a first pipe and a second oil outlet connected to the auxiliary circuit by a second pipe. The first pipe is connected to an oil recovery pump supplying the main tank and the second pipe is connected to an auxiliary pump of the auxiliary circuit.

[0017] Furthermore, according to this document, a radial partition is arranged in the internal cavity and delimits an upstream compartment and a downstream compartment, the second pipe being connected to the upstream compartment and the first pipe being connected to the downstream compartment.

[0018] Thus, during phases, for example, of free rotation of the fan during which the feed pump is not primed, the auxiliary pump draws the oil flowing by gravity into the arm located at 6 o'clock through the second pipe. The auxiliary circuit can therefore be supplied with oil to lubricate the reducer during these phases.

[0019] Although this solution provides an oil volume for auxiliary lubrication of the speed reducer in the event of, for example, free rotation of the fan, the oil volume available for these operating phases can be increased. Indeed, this document teaches that to maximize oil recovery, the oil inlet has a maximum axial dimension extending over the entire axial width of the arm, defined between the upstream and downstream edges of the arm. The combination of the configuration of the oil inlet with the presence of the radial wall hinders optimal oil recovery in the first pipe. Indeed, the oil flowing by gravity in the arm supplies both the upstream and downstream compartments. The main circuit can therefore be supplied with oil even though the auxiliary circuit does not benefit from a maximum volume during the free rotation operating phases of the fan.During these phases, although the lubrication of the reducer is guaranteed, it can be optimized.

[0020] There is therefore a need to provide a solution to optimize the lubrication of the speed reducer during all phases of operation of the turbomachine.

[0021] Summary of the invention

[0022] To this end, the invention proposes a casing for an aircraft turbomachine, the casing extending around a longitudinal axis, and comprising:

[0023] - an internal annular shell centered on the longitudinal axis and internally defining a lubrication enclosure, the internal annular shell having first and second axially opposite annular edges,

[0024] - an external annular ferrule arranged coaxially around the internal annular ferrule,

[0025] - arms extending radially between the inner and outer annular ferrules, one of the arms, called the 6h arm, being tubular and located at 6h, this 6h arm comprising: a radially outer end connected to the outer ferrule and a radially inner end connected to the inner ferrule, an internal cavity comprising a first compartment opening into the lubrication enclosure through an oil inlet provided in the inner ferrule, and a second compartment, a first oil outlet located in the second compartment, a second oil outlet located in the first compartment, the first and second oil outlets being radially offset relative to the radially inner end.

[0026] The casing according to the invention is remarkable in that the second compartment is separated from the lubrication enclosure by a cover extending longitudinally in the lubrication enclosure from the second annular edge to the oil inlet and in that the oil inlet is circumferentially delimited by first and second walls extending radially from the internal shell, on either side of the oil inlet.

[0027] Thanks to the cover separating the second compartment of the 6h arm from the first compartment of the 6h arm, in combination with the first and second walls delimiting the oil inlet, the oil flows preferentially into the first compartment which is intended to be connected to an auxiliary reservoir of an auxiliary lubrication circuit.

[0028] The auxiliary tank is therefore supplied with oil as a priority, which guarantees lubrication of the speed reducer when the auxiliary circuit is active.

[0029] Thanks to the housing of the invention, a larger volume of oil can be stored in the auxiliary tank to supply the auxiliary circuit. The speed reducer can therefore be lubricated optimally, reliably and efficiently during all phases of operation of the turbomachine.

[0030] The invention may comprise one or more of the following features, taken in isolation from each other or in combination with each other:

[0031] - the first and second walls extend longitudinally in the internal shell from the first annular edge to the second annular edge,

[0032] - the oil inlet is delimited axially by a third wall located between the first and second walls and extending radially in the first compartment,

[0033] - the third wall extends radially to the second oil outlet,

[0034] - first and second chutes arranged on either side of the first and second walls and configured to convey the oil from the lubrication enclosure to the oil inlet,

[0035] - the first and second chutes extend over an angular sector around the longitudinal axis of between 5° and 10°, - the 6h arm comprises a radial partition arranged in the internal cavity and separating the first compartment from the second compartment,

[0036] - the radially outer end of the 6h arm has a bottom wall in which the second oil outlet is provided, the partition extending radially towards the inside of the 6h arm from the bottom wall.

[0037] The invention also relates to a turbomachine for an aircraft, comprising a casing according to any one of the preceding characteristics.

[0038] The turbomachine may comprise one or more of the following features, taken in isolation from each other or in combination with each other:

[0039] - a fan driven in rotation around the longitudinal axis by a fan shaft,

[0040] - a low pressure shaft connected to the fan shaft by a mechanical speed reducer arranged in the lubrication enclosure,

[0041] - a speed reducer lubrication system comprising a main lubrication circuit and an auxiliary lubrication circuit connected to the lubrication enclosure of the casing, the auxiliary circuit being connected to an auxiliary reservoir, the auxiliary reservoir being located outside the outer shell of the casing, the first oil outlet being connected to the main circuit and the second oil outlet being connected to the auxiliary reservoir,

[0042] - the auxiliary tank is directly connected to the second oil outlet of the crankcase,

[0043] - the auxiliary tank is housed in an inter-vein compartment which is configured to separate an airflow produced by the blower into a primary flow and a secondary flow. -- the inter-vein compartment is located radially between a primary flow vein of the primary flow and a secondary flow vein of the secondary flow.

[0044] Brief description of the figures

[0045] Other characteristics and advantages will emerge from the following description of non-limiting embodiments of the invention with reference to the appended drawings in which: Figure 1 is a schematic representation in longitudinal section of an aircraft turbomachine according to the invention, Figure 2 is a schematic representation in longitudinal section of a speed reducer equipping the turbomachine of Figure 1, Figure 3 is a schematic view of a lubrication system of the speed reducer of Figure 2 according to an exemplary embodiment of the invention, Figure 4 is a schematic perspective view of a casing according to the invention, Figure 5 is another schematic perspective view of the casing of Figure 4, Figure 6 is a longitudinal section view of the casing of Figures 4 and 5.

[0046] Detailed description of the invention

[0047] 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.

[0048] In this application, the terms "axial", "axially", "radial", and "radially" are defined with respect to the longitudinal axis X.

[0049] The terms "upstream" and "downstream" are defined in relation to the direction of gas flow in the turbomachine 1 along the longitudinal axis X. The terms "internal", "interior", "external", "exterior",

[0050] "externally" are defined with respect to the distance from the longitudinal axis X along a radial axis Z perpendicular to the longitudinal axis X. The turbomachine 1 comprises from upstream to downstream, a fan 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.

[0051] The blower 2 allows the suction of an air flow F dividing into a primary flow F1 and a secondary flow F2. The primary flow F1 passes through a primary vein 1a of the turbomachine 1 while the secondary flow F2 is directed towards a secondary vein 1b surrounding the primary vein 1a.

[0052] The primary flow F1 is compressed within the low pressure compressor 3 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 turbines 6 and low pressure turbines 7. The gases finally escape through the nozzle, the cross-section of which allows the acceleration of these gases to generate propulsion.

[0053] The fan 2 is rotatable around the longitudinal axis X. The fan 2 comprises blades 2a regularly distributed around a disc centered on the longitudinal axis X.

[0054] 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 carried by a fan casing (not shown).

[0055] Furthermore, the turbomachine 1 comprises a casing 8. The casing 8 is for example an inlet casing. The casing 8 is for example arranged inside the nacelle 2b. The casing 8 is for example arranged axially between the fan 2 and the low-pressure compressor 3. The casing 8 forms an inlet nozzle of the primary stream 1a. The casing 8 comprises an annular outer shell 18 and an annular inner shell 19 arranged in the outer shell 18. The outer and inner shells 18, 19 are centered on the longitudinal axis X and connected by radial arms. Each of the outer and inner ferrules 18, 19 has a first annular edge 18a, 19a, in particular an upstream annular edge 18a, 19a and a second annular edge 18b, 19b, in particular a downstream annular edge 18b, 19b. The first and second annular edges 18a, 19a, 18b, 19b are axially opposite.

[0056] The primary vein 1 a is delimited downstream of the inlet nozzle by an internal casing 110 arranged downstream of the external shell 18 and the internal shell 19. The secondary vein 1 b is also delimited radially by the nacelle 2 b and an inter-vein casing 180 arranged radially between the nacelle 2 b and the casing 8.

[0057] Furthermore, an inter-vein compartment 1c is arranged radially between the secondary vein 1b and the primary vein 1a. The inter-vein compartment 1c has a first zone Z1 delimited internally by the external shell 18 and externally by the inter-vein casing 180. The inter-vein compartment 1c comprises a second zone Z2 downstream of the first zone Z1.

[0058] In the particular example of 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.

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

[0060] The fan 2 is driven in rotation by a fan shaft 11. The fan shaft 11 is connected to the disc for its rotational drive. The fan shaft 11 is supported by a downstream bearing 11a arranged radially between the fan shaft 11 and a second bearing support 11b connected to the inner shell 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 fan shaft 11.

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

[0062] As best seen in Figure 2, the speed reducer 12 comprises a sun gear 13, a ring gear 14, at least one satellite 15 which meshes with the ring gear 14 and the sun gear 13, and a planet carrier 16.

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

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

[0065] The crown 14 is annular and is arranged around the longitudinal axis X. According to the example of FIG. 1, the crown 14 is coupled in rotation with the fan shaft 11. The crown 14 comprises for example a fixing flange 14a connected to the fan shaft 11 for example by means of fixing rods 14b such as screws. The crown 14 forms the output of the reducer 12.

[0066] The planet carrier 16 is fixed in rotation around the longitudinal axis X. The planet carrier 16 is connected to a fixed structure of the turbomachine 1. According to the example of FIG. 2, the planet carrier 16 is connected to the internal shell 19, for example by means of a flexible support 11c.

[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 enclosure 17. The lubrication enclosure 17 is for example an upstream enclosure. The lubrication enclosure 17 is located inside the inner shell 19. The lubrication enclosure 17 is thus defined by the inner shell 19. It may comprise 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 internal shell 19. The lubricating oil flows by gravity into the chamber bottom F.

[0069] With reference to Figure 3, among the radial arms extending radially between the outer ferrule 18 and the inner ferrule 19, a tubular arm 20 is located at 6 o'clock (six o'clock) by analogy with the corresponding position on the dial of a clock. For simplification, in the remainder of the description, this 6 o'clock arm will be designated as "arm".

[0070] The arm 20 comprises a radially inner end 20a connected to the inner ferrule 19, in particular connected to the lubrication enclosure 17, in particular to the enclosure bottom F. The radially inner end 20a is for example open. The arm 20 further comprises a radially outer end 20b connected to the outer ferrule 18 and opposite the radially inner end 20a. The radially outer end 20b has for example a bottom wall 20b' preferably formed by the outer ferrule 18.

[0071] The arm 20 also has a first face and a second face that are opposite and extend radially between the radially outer end 20b and the radially inner end 20a. The first and second faces advantageously extend axially between the annular edges of the outer and inner ferrules 18, 19. The first and second faces meet at a first edge 201, in particular at an upstream edge 201, and a second edge 202, in particular a downstream edge 202. The upstream and downstream edges 201, 202 are axially connected to each other at their outer end by the bottom wall 20b'.

[0072] The arm 20 further comprises an internal cavity 200 comprising a first compartment 21 a, in particular an upstream compartment 21 a and a second compartment 21 b, in particular a downstream compartment 21 b. According to a preferred embodiment of the invention, the arm 20 comprises a radial partition 21 arranged in the internal cavity 200 and which separates the first and second compartments 20 a, 20 b. The radial partition 21 extends for example radially inwards from the bottom wall 20 b'. The first and second compartments 21 a, 21 b each have a predetermined volume. The first compartment 21 a opens into the lubrication enclosure 17 through an oil inlet 200 a. The lubricating oil can therefore flow by gravity outside the lubrication enclosure 17 into the arm 20. The oil inlet 200a is arranged for example in the internal shell 19 and opens into the first compartment 21a.

[0073] With reference to Figures 4 and 5, according to the invention, the oil inlet 200a is circumferentially delimited around the longitudinal axis X by first and second walls 23a, 23b. The first and second walls 23a, 23b are arranged on either side of the oil inlet 200a. The first and second walls 23a, 23b are located in the inner shell 19 and extend radially from the inner shell 19. They extend radially inward from the inner shell 19. They form, for example, a single piece with the inner shell 19. The inner shell 19 and the first and second walls 23a, 23b are integrally formed.

[0074] Preferably, the first and second walls 23a, 23b extend radially in the extension of the arm 20, that is to say in the extension of the first and second faces of the arm 20. The first and second walls 23a, 23b extend longitudinally in the internal shell 19. They extend between the first annular edge 19a and the second annular edge 19b, preferably from the first annular edge 19a to the second annular edge 19b of the internal shell 19. The first and second walls 23a, 23b are parallel to each other. The first and second walls 23a, 23b have a height h1 as measured along the radial axis Z which is preferably identical.

[0075] Referring to Figures 4 to 6, according to a preferred embodiment of the invention, the oil inlet 200a is axially delimited by a third wall 23c. The third wall 23c is arranged between the first and second walls 23a, 23b. It extends radially inward from the inner shell 19 and perpendicular to the first and second walls 23a, 23b. The third wall 23c extends radially into the first compartment 21a. It is arranged upstream of the partition 21.

[0076] According to the invention, the second compartment 21 b is separated from the lubrication enclosure 17 by a cover 22. The cover 22 thus makes it possible to close the second compartment 21 b at its internal end so that the oil flows exclusively into the first compartment 21 a.

[0077] The cover 22 extends longitudinally in the lubrication enclosure 17 from the second annular edge 19b to the oil inlet 200a. The cover 22 thus has an upstream end 22a located on the side of the oil inlet 200a and an axially opposite downstream end 22b. Thus, the third wall 23c is axially offset downstream relative to the upstream end 22a of the cover 22. This makes it possible to further limit the risk of oil flowing from the lubrication enclosure 17 into the second compartment 21b.

[0078] According to a preferred embodiment of the invention, the cover 22 is integral with the first and second walls 23a, 23b. The cover 22 is fixed to the first and second walls 23a, 23b by bolting. For example, lugs 23c extend projecting from the first and second walls 23a, 23b. The lugs 23c of the first wall 23a are oriented towards the lugs 23c of the second wall 23b. The lugs 23c of the first and second walls 23a, 23b are for example arranged in a staggered pattern. The cover 22 is connected to the lugs 23c by bolts 22c.

[0079] Advantageously, the cover 22 has a circumferential width equal to a circumferential width of the arm 20. The cover 22 extends circumferentially between the first and second faces of the arm 22. This makes it possible to prevent oil from flowing by gravity into the second compartment 21b.

[0080] According to a preferred embodiment of the invention, the casing 8 further comprises first and second chutes 32a, 32b arranged on either side of the first and second walls 23a, 23b. The first and second chutes 32a, 32b are configured to convey the oil from the lubrication enclosure 17 to the oil inlet 200a and thus promote the flow of oil into the first compartment 21a. The first and second chutes 32a, 32b extend from the first and second walls 23a, 23b, opposite the second annular edge 19b of the internal shell 19. They are thus located on the side of the oil inlet 200a. The first and second chutes 32a, 32b extend around the longitudinal axis X over an angular sector of between 5° and 10°.

[0081] With reference to Figure 3, the arm 20 further comprises a first oil outlet 20c and a second oil outlet 20d radially opposite the oil inlet 200a. They are for example arranged in the bottom wall 20b' and / or the downstream edge 202. The first outlet 20c is for example arranged in the downstream edge 202 and the second outlet 20d is for example arranged in the bottom wall 20b'.

[0082] The first outlet 20c is located in the second compartment 21b, therefore the downstream compartment 21b and the second outlet 20d is located in the first compartment 21a therefore the upstream compartment 21a. Preferably, the third wall 23c extends to the second outlet 20d.

[0083] In order to ensure the lubrication of the speed reducer 12 in the lubrication enclosure 17, the turbomachine 1 comprises a system for lubricating the speed reducer 12.

[0084] The lubrication system comprises a main lubrication circuit 24, an auxiliary lubrication circuit 25, the main and auxiliary circuits 24, 25 being connected to the lubrication enclosure 17. The lubrication system 23 may further comprise a selective projection device 26 for spraying the lubricating oil into the lubrication enclosure 17, this selective projection device 26 being connected to the main circuit 24 and to the auxiliary circuit 25.

[0085] The main circuit 24 typically comprises a supply circuit 240 connecting a main reservoir 240b to the lubrication enclosure 17. The supply circuit 240 comprises a supply pump 240a mounted between the main reservoir 240b and the lubrication enclosure 17, in particular between the main reservoir 240b and the selective projection 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 rotated, it primes the feed pump 240a which draws oil from the main reservoir 240b and supplies oil to the selective projection device 26.The supply circuit 240 may further comprise at least one air / oil exchanger 240c arranged for example between the selective projection device 26 and the supply pump 240a.

[0086] The main circuit 24 further comprises a return circuit 241 connecting the main reservoir 240b to the second compartment 21b of the arm 20. The return circuit 241 comprises 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 first outlet 20c of the arm 20. In particular, the recovery pump 241a has an inlet hydraulic line 242a connected to the first outlet 20c and an outlet hydraulic line 242b which is connected to the main reservoir 240b. In certain cases, the high-pressure shaft 9 is not driven in rotation or driven at a rotation speed insufficient to drive the feed pump 240a in rotation.For example, when the fan 2 is in free rotation (or auto rotation, also known by the English expression “windmilling”), or during the start or stop phases of the turbomachine 1, the feed pump 240a is not primed and is no longer capable of supplying oil to the selective projection device 26. The speed reducer 12 is then no longer lubricated by the main circuit 24. The lubrication of the speed reducer 12 is ensured in such a case by the auxiliary circuit 25. The auxiliary circuit 25 is a closed circuit for lubricating the lubrication enclosure 17. It comprises an auxiliary pump 28 connected to an auxiliary reservoir 31 and to the lubrication enclosure 17, in particular to the selective projection device 26.

[0087] The auxiliary tank 31 is located outside the outer shell 18. Preferably, the auxiliary tank 31 is arranged in the inter-vein compartment 1 c, for example in the first zone Z1. The auxiliary tank 31 being located outside the primary vein 1 a, the auxiliary tank 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.

[0088] The auxiliary tank 31 is connected to the second oil outlet 20d of the arm 20. Thus, the auxiliary tank 31 and the first compartment 21a are communicating. The oil flowing by gravity into the first compartment 21a is stored in the auxiliary tank 31.

[0089] Thanks to the cover 22 of the invention, the auxiliary tank 31 is filled as a priority. The risks of undersupplying the auxiliary tank 31 with oil are limited. This ensures the lubrication of the speed reducer 12 in an optimal and reliable manner whatever the operating phases of the turbomachine 1.

[0090] Preferably, the auxiliary tank 31 is directly connected to the second oil outlet 20d of the arm 20.

[0091] 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 1c. The electric motor 29 is supplied with electrical energy by an electric generator (not shown) for example located in the lubrication enclosure 17. The electric generator makes it possible to supply electrical energy to the electric motor 29 from mechanical energy. The electric generator takes for example mechanical energy from the fan shaft 11. For example, the electric generator is connected to the fan shaft 11 via gears 30.

[0092] The electric motor is for example controlled by a control unit 290. The control unit 290 makes it possible to modulate the speed of the auxiliary pump 28 via the electric motor. The control unit is for example a FADEC (for “Full Automatic Digital Engine Control” in English).

[0093] According to another example, the auxiliary pump 28 is driven by the low pressure shaft 10.

[0094] The selective spraying device 26 comprises, for example, a selection member 27' and at least one nozzle 27 which is arranged in the lubrication enclosure 17. The selection member 27' is, for example, a selection valve connected to the main and auxiliary circuits 24, 25.

[0095] The nozzle 27 makes it possible to spray the lubricating oil into the lubrication enclosure 17. The selective spraying device 26 advantageously comprises two nozzles 27, a first nozzle spraying the lubricating oil onto the speed reducer 12 and a second nozzle spraying the oil onto the gears 30. 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.

[0096] The operation of the main and auxiliary circuits 24, 25 will now be described.

[0097] In a first phase of operation, the turbomachine 1 is stopped. The main and auxiliary circuits 24, 25 are therefore stopped. In this first phase, the auxiliary tank 31 contains oil remaining from a previous flight.

[0098] In a first phase of nominal operation of the turbomachine 1, the auxiliary circuit 25 is inactive, that is to say the auxiliary pump 28 is inactive. The main circuit 24 is active, that is to say the feed pump 240a is active and draws oil from the main reservoir 240b. The oil is conveyed to the lubrication enclosure 17 by the main circuit 24. In this first phase, the lubricating oil flows by gravity into the enclosure bottom F and flows into the arm 20. Thanks to the cover 22, the oil flows preferentially into the first compartment 21a. This oil is stored in the auxiliary reservoir 31. In this phase, the volume of oil in the first compartment 21a is less than the maximum volume of the first compartment 21a. The recovery pump 241a is also, for example, active.

[0099] In a second phase of nominal operation of the turbomachine 1, the main circuit 24 is still active but the volume of oil in the auxiliary tank 31 is greater than the maximum volume of the auxiliary tank 31 and the maximum volume of the first compartment 21 a. The oil is transferred for example by overflow into the second compartment 21 b. The recovery pump 241 a in this second phase then sucks oil from the second compartment 21 b and then allows the circulation of the oil in the return circuit 241 of the main circuit 24 to supply the main tank 240 b with oil.

[0100] In a third phase of operation of the turbomachine 1, for example in the event of free rotation of the fan 2 and stoppage or insufficient rotation speed of the high pressure shaft 10, the pressure in the main circuit 24 decreases such that the selection member 27' becomes supplied by the auxiliary circuit 25 in which the oil pressure is higher. Indeed, the feed pump 240a is then de-primed or provides an insufficient flow rate, while the auxiliary circuit 25 is active. The auxiliary pump 28 draws the oil from the auxiliary reservoir 31 and allows its circulation in the auxiliary circuit 25 for the lubrication of the reducer 12 in the lubrication enclosure 17.

[0101] Thanks to the invention, it is possible to increase the volume of the auxiliary tank 31 without impacting the aerodynamic performance and the size of the turbomachine 1.

[0102] Thanks to the invention, it is possible to guarantee an optimal oil volume in the auxiliary reservoir 31 for the lubrication of the speed reducer 12 in the lubrication enclosure 17 in the event of the supply pump 240a of the main circuit 24 being stopped, for example in the event of free rotation of the fan 2.

Claims

CLAIMS 1. Casing (8) for an aircraft turbomachine (1), the casing (8) extending around a longitudinal axis (X), and comprising: - an internal annular shell (19) centered on the longitudinal axis (X) and internally defining a lubrication enclosure (17), the internal annular shell (19) having first and second axially opposite annular edges (19a, 19b), - an external annular ferrule (18) arranged coaxially around the internal annular ferrule (19), - arms extending radially between the inner and outer annular ferrules (19, 18), one of the arms, called the 6h arm (20), being tubular and located at 6h, this 6h arm (20) comprising: a radially outer end (20b) connected to the outer ferrule (18) and a radially inner end (20a) connected to the inner ferrule (19), an internal cavity (200) comprising a first compartment (21a) opening into the lubrication enclosure (17) through an oil inlet (200a) formed in the inner ferrule (19), and a second compartment (21b), a first oil outlet (20c) located in the second compartment (21b), a second oil outlet (20d) located in the first compartment (21a), the first and second oil outlets (20c, 20d) being radially offset relative to the end radially internal (20a),characterized in that the second compartment (21 b) is separated from the lubrication enclosure (17) by a cover (22) extending longitudinally in the lubrication enclosure (17) from the second annular edge (19b) to the oil inlet (200a) and in that the oil inlet (200a) is circumferentially delimited by first and second walls (23a, 23b) extending radially from the internal shell (19), on either side of the oil inlet (200a)., 2. Casing according to the preceding claim, characterized in that the first and second walls (23a, 23b) extend longitudinally in the internal shell (19) from the first annular edge (19a) to the second annular edge (19b).

3. Housing according to any one of the preceding claims, characterized in that the oil inlet (200a) is delimited axially by a third wall (23c) located between the first and second walls (23a, 23b) and extending radially in the first compartment (21a).

4. Housing according to the preceding claim, characterized in that the third wall (23c) extends radially to the second oil outlet (20d).

5. Housing according to any one of the preceding claims, characterized in that it comprises first and second chutes (32a, 32b) arranged on either side of the first and second walls (23a, 23b) and configured to convey the oil from the lubrication enclosure (17) to the oil inlet (200a).

6. Housing according to the preceding claim, characterized in that the first and second chutes (32a, 32b) extend over an angular sector around the longitudinal axis (X) of between 5° and 10°.

7. Housing according to any one of the preceding claims, characterized in that the 6h arm (20) comprises a radial partition (21) arranged in the internal cavity (200) and separating the first compartment (21 a) from the second compartment (21 b).

8. Housing according to the preceding claim, characterized in that the radially external end (20b) of the 6h arm (20) has a bottom wall (20b') in which the second oil outlet (20d) is formed, the partition (21) extending radially towards the inside of the 6h arm (20) from the bottom wall (20b').

9. Turbomachine (1) for an aircraft, characterized in that it comprises a casing (8) according to any one of the preceding claims.

10. Turbomachine according to the preceding claim, characterized in that it further comprises: - a fan (2) driven in rotation around the longitudinal axis (X) by a fan shaft (11), - a low pressure shaft (10) connected to the fan shaft by a mechanical speed reducer (12) arranged in the lubrication enclosure (17), - a lubrication system for the speed reducer (12) comprising a main lubrication circuit (24) and an auxiliary lubrication circuit (25) connected to the lubrication enclosure (17) of said casing (8), the auxiliary circuit (25) being connected to an auxiliary reservoir (31), the auxiliary reservoir (31) being located outside the external shell (18) of said casing (8), the first oil outlet (20c) being connected to the main circuit (24) and the second oil outlet (20d) being connected to the auxiliary reservoir (31).

11. Turbomachine according to the preceding claim, characterized in that the auxiliary reservoir (31) is directly connected to the second oil outlet (20d) of said casing (8).

12. Turbomachine according to claim 10 or 11, characterized in that the auxiliary tank (31) is housed in an inter-vein compartment (1c) which is configured to separate an air flow (F) produced by the fan (2) into a primary flow (F1) and a secondary flow (F2).

Images