Turbine engine comprising accessory drive, lubrication unit and oil tank

Abstract

The invention relates to a turbine engine (1) comprising:-a housing (4 ', 12); -an accessory drive (20) suspended on the housing and connected to the housing (4 ', 12) and comprising a housing (22) defining an inner cavity and a gear train arranged in the inner cavity; -a lubrication unit (26) comprising: a device housing (28) fixed and attached to the housing (22), at least one pump (29) located in the device housing (28) and comprising a rotor coupled to the gear train, and an oil inlet (31) connected to the pump (29); -an oil tank (27) comprising an oil outlet (34) connected to the oil inlet (31) of the lubrication unit (26), characterized in that the tank (27) is attached directly to the equipment housing (28) and arranged above the lubrication unit (26) such that oil flows into the lubrication unit (26) under the action of gravity.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of aircraft turbine engines.

[0002] The present invention particularly relates to the field of turbine engines comprising an accessory gearbox, a lubrication unit and an oil tank. BACKGROUND

[0003] The prior art is illustrated by documents US-A1-2012 / 0159966 and US-A1-2018 / 0195413.

[0004] An aircraft turbine engine generally extends along and around a longitudinal axis. An aircraft turbine engine comprises, in the gas flow direction of the turbine engine, from upstream to downstream, a fan, a low pressure compressor, a high pressure compressor, a gas combustion chamber, a high pressure turbine and a low pressure turbine.

[0005] A turbine engine generally comprises an engine compartment delimited radially by an engine casing surrounding the compressor, the combustion chamber and the turbine.

[0006] In a configuration of the turbine engine with a ducted fan, the turbine engine further comprises a fan compartment delimited radially by a fan casing surrounding the fan. In a configuration of the turbine engine with a non-ducted fan, the turbine engine does not comprise a fan casing and therefore does not comprise a fan compartment.

[0007] Furthermore, the rotor of the low pressure compressor is generally connected to the rotor of the low pressure turbine by a low pressure shaft. The rotor of the high pressure compressor is connected to the rotor of the high pressure turbine by a high pressure shaft. The shafts are guided in rotation by guide bearings which need to be lubricated to ensure the correct operation of the guide bearings.

[0008] It is therefore known to inject lubricating oil onto the guide bearings. In order to protect the relevant components of the turbine engine from this lubricating oil, the guide bearings are generally arranged in a lubrication enclosure.

[0009] In order to lubricate the bearings in the lubrication enclosure, the turbine engine generally comprises an oil circuit. The oil circuit is generally a closed circuit comprising a bearing lubrication circuit and possibly an oil recovery circuit from the lubrication enclosure. The oil circuit generally comprises a lubrication unit connected to the oil tank by an oil entry pipe and possibly an oil return pipe. The lubrication unit comprises at least one feed pump to draw in oil from the tank and to distribute the oil to the lubrication enclosure by a feed circuit. The lubrication unit generally comprises a device housing in which at least one rotor of the feed pump is arranged, and at least one pump oil inlet connected to the tank by an entry pipe.

[0010] In order to drive the rotor of the supply pump of the lubrication unit, it is known for the lubrication unit to be fitted and attached to an accessory gearbox, known as an accessory gearbox (AGB). The accessory gearbox is used to transmit mechanical power from the turbine engine to the accessories of the turbine engine, such as the lubrication unit pump. The accessory gearbox generally comprises a housing comprising an upstream face and a downstream face defining between them an internal cavity in which a gear train having a series of pinions meshing with each other is arranged. The housing of the lubrication unit is attached to one of the faces of the gearbox and the rotor of the supply pump is rotationally coupled to one of the pinions of the gear train.

[0011] In a turbine engine architecture with a ducted fan, the tank and the accessory gearbox carrying the lubrication unit are generally located in the fan compartment. The oil tank is attached to the outside of the fan case, to a first portion of the fan case, while the accessory gearbox carrying the lubrication unit overhangs the outside of the fan case at a lower portion than the first portion to which the oil tank is attached.

[0012] However, this configuration is not suitable for a turbine engine with a non-ducted fan, which does not comprise a fan compartment and therefore a fan case. It was therefore decided to move the oil tank and the accessory gearbox carrying the lubrication unit into the engine compartment and to attach the oil tank to one of the engine cases and to overhang the same engine case with the accessory gearbox.

[0013] However, arranging the fuel tank and the accessory gearbox carrying the lubrication unit in the engine compartment is not easy, considering the size of the fuel tank and the small diameter of the case compared to the diameter of the fan case. A large part of the volume of the tank is located in the upper portion of the engine compartment, i.e. in the upper half extending between 9 o'clock and 3 o'clock in azimuthal position, for the lubrication needs in all cases, in particular in zero gravity (0g) or negative gravity (negative g) conditions, or when the aircraft is at high angles of attack. This gives the tank a high tangential height. However, considering the small diameter of the engine cases and the fact that the lower portion of the engine compartment is occupied by the accessory gearbox and the upper portion by the thrust link, for example, the engine compartment does not have enough space to accommodate such a tank. This space is even less sufficient since it is necessary to provide a distance between the tank and the lubrication unit to accommodate and install the access duct connecting the tank to the lubrication unit. This problem is further complicated by the need to ensure the flexibility of the access duct connecting the lubrication unit, which is subjected to the movements imposed by the accessory gearbox, and the tank, which is rigidly attached to the engine case due to its overall size.

[0014] In this context, there is a need to provide a turbine engine comprising an accessory gearbox, a lubrication unit and an oil tank, the overall size of which is reduced so as to facilitate the integration of this assembly in a turbine engine with a ducted fan and a non-ducted fan. SUMMARY

[0015] To this end, the application proposes a turbine engine for an aircraft, the turbine engine having a longitudinal axis and comprising: - an annular casing centered on the longitudinal axis, - an accessory gearbox located outside the casing and suspended from the casing, the accessory gearbox being connected to the casing and comprising: a housing defining an internal cavity, and a gear train arranged in the internal cavity, - a lubrication unit comprising: a device housing fitted and attached to the housing of the accessory gearbox, at least one pump located in the device housing and comprising a rotor coupled to the gear train, and an oil inlet connected to the pump, and - an oil tank comprising an oil outlet connected to the oil inlet of the lubrication unit.

[0016] The turbine engine is remarkable in that the tank is directly attached to the device housing and located above the lubrication unit, so that the oil flows by gravity into the lubrication unit.

[0017] According to the application, the tank is directly attached to the device housing of the lubrication unit. This feature eliminates the need for a pipe connecting the oil outlet of the tank to the oil inlet of the lubrication unit. In the absence of such a pipe, the radial or angular space around the casing between the tank and the lubrication unit is significantly reduced or eliminated, thereby reducing the overall size of the assembly. Thus, the assembly formed by these two elements can be arranged in the narrow engine compartment of a turbine engine, generally around the high-pressure compressor casing or intermediate casing, the diameter of which is smaller than that of the fan casing, so that the space available to accommodate the assembly is smaller.

[0018] Thanks to the application, it is possible to arrange the tank and the lubrication unit in a turbine engine with a non-ducted fan and in a turbine engine with a ducted fan.

[0019] In addition, the number of interfaces is reduced, thus simplifying the installation, maintenance and disassembly of the turbine engine. The weight of the assembly is also greatly reduced.

[0020] The tank is also located above the lubrication unit. Thanks to this configuration, the oil flows by gravity into the lubrication unit without forming air bubbles. The pump of the lubrication unit sucks in little air or no air, which means that the lubrication circuit to which the lubrication unit is connected remains under sufficient pressure.

[0021] The application can comprise one or more of the following features taken alone or in combination with each other: - the tank extends angularly around the longitudinal axis between a first end located at an angular position comprised between 12h and 2h and an opposite end located at an angular position comprised between 3h and 4h; - the housing of the accessory gearbox extends angularly around the longitudinal axis between a first circumferential end located at an angular position comprised between 9h and 7h and a second circumferential end located at an angular position comprised between 3h and 5h; - the housing comprises an upstream surface and a downstream surface extending between the first circumferential end and the second circumferential end, the equipment housing being fitted and attached to the downstream surface at the second circumferential end; - a radial suspension arm connecting the accessory gearbox to the casing; - a connecting arm connecting the accessory gearbox to the tank; - a support radially arranged between the casing and the tank and extending over an angular sector around the casing, and - at least one connecting arm connecting the support to the casing, the support being attached to the tank and to the accessory gearbox; - the support is attached to the accessory gearbox by bolts; - the support has a first end attached to the tank and an opposite end attached at the second circumferential end of the gearbox; - at least one connecting arm connecting the tank to the casing; - the tank is attached to the equipment housing by bolts; - the equipment housing is attached to the housing of the accessory gearbox by welding, bolting or flanging; - the turbo engine comprises, from upstream to downstream: - a fan, - a low-pressure compressor; - a high-pressure compressor; - a high-pressure turbine, mechanically connected to the high-pressure compressor, and - a low-pressure turbine, mechanically connected to the low-pressure compressor, the casing being located around the high-pressure compressor or arranged axially between the low-pressure compressor and the high-pressure compressor. BRIEF DESCRIPTION OF DRAWINGS

[0022] Other features and advantages will appear in the light of the following description of non-limiting embodiments according to the application, and with reference to the appended drawings, in which: Figure 1 is a longitudinal cross-sectional view of an example of an aircraft turbine engine according to the application; Figure 2 is a schematic perspective view of a gas generator of a turbine engine in Figure 1 Figure 3 is a schematic perspective view of an accessory gearbox equipped on a turbine engine of the application, Figure 4 is a schematic view of an oil circuit comprising a lubrication circuit and an oil recovery circuit, Figure 5 is a schematic perspective view of a lubrication unit equipped on a turbine engine of the application, Figure 6 is a schematic perspective view of an oil tank equipped on a turbine engine of the application, Figure 7 is a perspective view of a portion of a turbine engine showing the attachment of a tank to the turbine engine according to a first embodiment of the application; Figure 8 is a cross-sectional view of a turbine engine showing the attachment of a tank to the turbine engine according to a second embodiment of the application; Figure 9 is a cross-sectional view of a turbine engine showing the attachment of a tank to the turbine engine according to a third embodiment of the application. DETAILED DESCRIPTION

[0023] An example of an aircraft turbine engine 1 according to the application is very briefly shown in Figure 1 and Figure 2 The turbine engine 1 is for example a turbojet engine.

[0024] The turbine engine 1 extends along a longitudinal axis X. An air flow F flows through the turbine engine 1.

[0025] For the purposes of the application, the terms "upstream" and "downstream" are understood with respect to the direction of flow of the air flow F along the longitudinal axis X in the turbine engine 1.

[0026] The terms "longitudinal" and "longitudinally" refer to the longitudinal axis X of the turbine engine 1. The terms "radial" and "radially" refer to a radial axis perpendicular to the longitudinal axis X. The terms "outboard" and "inboard" are understood with respect to the distance from the longitudinal axis X along a radial axis perpendicular to the longitudinal axis X.

[0027] The terms "bottom" and "top" refer to a nominal position of the turbine engine 1. ​

[0028] The angular position in hours is measured around the longitudinal axis X in the nominal position of the turbine engine 1, the angular position in hours being understood by analogy with the corresponding position of a hand on a clock face when viewed from the front (upstream) of the turbine engine 1. The nominal operating position of the turbine engine 1 is the position in which the longitudinal axis X is perpendicular to the direction of gravity and in which the turbine engine 1 is in the mounted position on the aircraft.

[0029] Thus, generally, in the nominal position, the wing of the aircraft is located at 12 o'clock.

[0030] The term "case" is used in the present application to denote a fixed annular structural element of the turbine engine 1.

[0031] The turbine engine 1 comprises, from upstream to downstream, a fan 2 and a gas generator comprising a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6 and a low-pressure turbine 7.

[0032] Each compressor 3, 4 comprises a compressor rotor 3a, 4a and each turbine 6, 7 comprises a turbine rotor 6a, 7a. The compressor rotors 3a, 4a and the turbine rotors 6a, 7a are constituted by a plurality of stages, each stage comprising an impeller.

[0033] The compressor rotor 3a of the low-pressure compressor 3 is connected to the turbine rotor 7a of the low-pressure turbine 7 by a low-pressure shaft 8. The compressor rotor of the low-pressure compressor and the turbine rotor of the low-pressure turbine form a low-pressure body.

[0034] The compressor rotor 4a of the high-pressure compressor 4 is connected to the turbine rotor 6a of the high-pressure turbine 6 by a high-pressure shaft 9. The compressor rotor of the high-pressure compressor and the turbine rotor of the high-pressure turbine form a high-pressure body.

[0035] The low-pressure shaft 8 and the high-pressure shaft 9 are centred on the longitudinal axis X and are capable of rotational movement around the longitudinal axis X. The high-pressure shaft 9 is arranged coaxially around the low-pressure shaft 8.

[0036] The air flow F passes through the fan 2 and is divided into a primary air flow Fl which passes through the primary duct vl and a secondary air flow F2 which passes through the secondary duct v2 surrounding the primary duct. The primary air flow Fl passes through the low-pressure compressor 3 and the high-pressure compressor 4. The compressed primary air flow Fl passes through the combustion chamber 5 in which it is mixed with fuel injected into the combustion chamber 5 via a supply injector 5'. The gases resulting from the combustion pass through the high-pressure turbine 6 and the low-pressure turbine 7, then escape through the exhaust casing 7' and the exhaust nozzle 200. The energy in the gases is converted into mechanical energy by the turbine rotor 6a of the high-pressure turbine 6 and the turbine rotor 7a of the low-pressure turbine 7 to drive the high-pressure shaft 9 and the low-pressure shaft 8 in rotation, thus driving the high-pressure compressor 4 and the low-pressure compressor 3 in rotation.

[0037] The fan 2 comprises a disc which can rotate about a longitudinal axis X and mobile blades 2a which are uniformly distributed on the disc. Preferably, the fan 2 is unshrouded. Contrary to a shrouded fan 2, the fan 2 does not comprise a fan casing surrounding the blades 2a. According to this example, the fan 2 can also comprise fixed blades arranged downstream of the mobile blades 2a. Advantageously, these fixed blades have a variable pitch angle and are connected to a blade pitch control system comprising hydraulic actuators, for example hydraulic cylinders.

[0038] In another example, not shown, the fan 2 is shrouded.

[0039] The disc of the fan 2 is driven in rotation by a fan shaft 10. Advantageously, the fan shaft 10 is connected to the low-pressure shaft 8, for example through a reduction gear 11. The reduction gear 11 is mechanical. For example, the reduction gear can have a epicyclic or planetary gear. Not shown, the reduction gear 11 generally comprises a ring gear and a sun gear which are centred on the longitudinal axis X. The reduction gear also comprises planetary gears which mesh with the sun gear and the ring gear. The reduction gear also comprises a planet carrier.

[0040] The sun gear is rotationally fixed to the low-pressure shaft 8 and forms the input of the reduction gear 11, while according to the configuration of the reduction gear 11, one or the other of the ring gear and the planet carrier is rotationally fixed to the fan shaft 10 and forms the output of the reduction gear 11.

[0041] The reduction gear 11 makes it possible for the fan shaft 10 to be driven at a lower speed than the rotation speed of the low-pressure shaft 8.

[0042] The turbo engine 1 also comprises at least one annular casing enabling the main air flow Fl and / or the secondary air flow F2 to be channelled into the turbo engine 1 and, if necessary, to absorb the forces exerted on the turbo engine 1. In particular, the turbo engine 1 comprises an annular inter-compressor casing 12 arranged axially between the low-pressure compressor 3 and the high-pressure compressor 4. For example, the inter-compressor casing 12 comprises an outer shell and an inner shell centred on the longitudinal axis X. The inner shell and the outer shell are connected, for example, by arms.

[0043] The turbo engine 1 can also comprise an annular intake casing 13. The intake casing 13 is arranged axially between the fan 2 and the low-pressure compressor 3. For example, the intake casing 13 comprises an outer shell and an inner shell centred on the longitudinal axis X. The inner shell and the outer shell are connected, for example, by arms.

[0044] The turbo engine 1 can also comprise an annular inter-turbine casing 14. The inter-turbine casing 14 is arranged axially between the high-pressure turbine 6 and the low-pressure turbine 7.

[0045] The turbo engine 1 also comprises an annular compressor casing 4' centred on the longitudinal axis X. The compressor casing 4' is arranged so as to surround the rotor of the high-pressure compressor 4 and is connected to the combustion chamber 5. The turbo engine 1 also comprises a turbine casing 6' surrounding the high-pressure turbine 6 and the low-pressure turbine 7 and connected to an exhaust casing 7'.

[0046] The fan shaft 10 is guided in rotation by a first bearing 15a and advantageously by a second bearing 15b. The first bearing 15a and the second bearing are arranged radially between the fan shaft 10 and the intake casing 13. For example, each first bearing 15a and second bearing 15b comprises a rolling bearing arranged between an outer ring and an inner ring. The outer ring is carried by a first bearing support 16a extending radially inwards from the intake casing 13. The inner ring is carried by the fan shaft 10. For example, the rolling bearing is a row of balls. Advantageously, the rolling bearing comprises two rows of balls.

[0047] The low-pressure shaft 8 is guided in rotation by at least a third bearing 15c and a fourth bearing 15d. The third bearing 15c is arranged radially between the intake casing 13 and the low-pressure shaft 8. The third bearing 15c comprises a rolling bearing, for example a row of balls, arranged radially between an inner ring and an outer ring. The outer ring is carried by a second bearing support 16b connected to the intake casing 13. The inner ring is carried by the low-pressure shaft 8. The fourth bearing 15d is arranged radially between the inter-compressor casing 12 and the low-pressure shaft 8. The fourth bearing 15d comprises a rolling bearing, for example a row of balls, arranged radially between an inner ring and an outer ring. The outer ring is carried by a third bearing support 16b connected to the inter-compressor casing 12. The inner ring is carried by the low-pressure shaft 8.

[0048] The high-pressure shaft 9 is guided in rotation by a fifth downstream bearing 15e and a fifth upstream bearing 15g. For example, the fifth downstream bearing 15e is radially arranged between the high-pressure shaft 9 and the inter-turbine casing 14. The fifth downstream bearing 15e comprises a rolling bearing, for example a row of balls and a row of rollers, radially arranged between an outer ring and an inner ring. The inner ring is carried by the high-pressure shaft 9 and the outer ring is carried by a fourth bearing support 16d connected to the inter-turbine casing 14. For example, the fifth upstream bearing 15g is located between the high-pressure shaft 9 and the compressor inter-casing 12.

[0049] For example, the low-pressure shaft 8 can be guided in rotation downstream by a sixth bearing 15f radially arranged between a downstream end of the low-pressure shaft 8 and the inter-turbine casing 14.

[0050] The bearings 15a, 15b, 15c, 15d, 15e, 15f, 15g and the reducer 11 must be lubricated with oil to ensure proper operation of these bearings. In order not to contaminate the relevant components of the turbine engine 1 with oil, the bearings 15a, 15b, 15c, 15d, 15e, 15f, 15g and the reducer 11 are arranged in lubrication housings.

[0051] To this end, the turbine engine 1 also comprises at least one lubrication housing, in particular a first upstream housing 17, a second upstream lubrication housing 18 and a downstream lubrication housing 19, the first bearing 15a, the second bearing 15b and the third bearing 15c and the reducer 11 being arranged in the first upstream housing, the fourth bearing 15d and the fifth upstream bearing 15g being arranged in the second upstream lubrication housing, the fifth bearing 15e and the sixth bearing 15f being arranged in the downstream lubrication housing.

[0052] The upstream lubrication housings 17, 18 and the downstream lubrication housing 19 are annular. Each upstream lubrication housing 17, 18 and the downstream lubrication housing 19 is externally delimited by a fixed part, such as a casing, and is internally delimited by a rotating part, such as a shaft.

[0053] For example, the first upstream lubrication housing 17 is located in the inner casing of the intake casing 13 and is internally delimited by the fan shaft 10. The second upstream lubrication housing 18 is located in the inner casing of the compressor inter-casing 12 and is internally delimited by the low-pressure shaft 8, the downstream lubrication housing 18 is located in the inner casing of the inter-turbine casing 14 and is internally delimited by the high-pressure shaft 9.

[0054] The number of lubrication housings can vary depending on the configuration of the turbine engine 1. In the following, the upstream lubrication housings 17, 18 and the downstream lubrication housing 19 will be interchangeably referred to as "lubrication housings".

[0055] Reference Figure 2The turbo engine 1 also comprises at least one thrust link 100 to absorb the axial forces generated by the fan 2. The thrust link 100 is connected upstream to the intermediate casing 12 and downstream to the exhaust casing 7' by a pylon 102. For example, the thrust link 100 is connected to the inner casing of the intermediate casing 12. Thus, the thrust link 100 is positioned around the compressor casing 4', the combustion chamber 5 and the turbine casing 6'. The pylon 102 connects the turbo engine 1 to the aircraft.

[0056] The turbo engine 1 comprises an accessory gearbox 20 for mechanically driving the equipment of the turbo engine 1 (also called accessories) by drawing mechanical power from one of the shafts 8, 9 of the turbo engine 1.

[0057] For example, the gearbox 20 is manufactured by additive manufacturing, by machining from solid or by investment casting.

[0058] Advantageously, the accessory gearbox 20 is located downstream of the fan 2 and on the outside of one of the casings. Preferably, the accessory gearbox 20 is located on the outside of the compressor casing 4', i.e. around this casing. In another example, the accessory gearbox 20 can be located on the outside of the inner casing of the intermediate casing 12. In the rest of the present description, the term "casing" will be used interchangeably to designate the compressor casing 4' or the intermediate casing 12, in particular the inner casing of this intermediate casing 12.

[0059] According to the invention, the accessory gearbox 20 is suspended on the casing 4', 12. Suspended means that the accessory gearbox 20 is connected to the casing 4', 12 and is located at the lowest point of the turbo engine 1. Thus, the accessory gearbox 20 is located below a horizontal plane P parallel to and passing through the longitudinal axis X.

[0060] For example, the accessory gearbox 20 (referred to simply as "gearbox") is shown in Figure 3 The accessory gearbox 20 extends angularly around the longitudinal axis X between a first circumferential end 21a and a second circumferential end 21b. Preferably, the first circumferential end 21a is located at an angular position of between 9 o'clock and 7 o'clock around the longitudinal axis X and the second circumferential end 21b is located at an angular position of between 3 o'clock and 5 o'clock around the longitudinal axis X.

[0061] The gearbox 20 comprises a housing 22. The housing 22 extends from the first circumferential end 21a to the second circumferential end 21b. The housing 22 has an upstream face 23a and a downstream face 23b connected by an inner face 23c and an outer face 23d.

[0062] The gearbox 20 further comprises at least one U-shaped clip for suspending on the casing 4', 12. For example, a first U-shaped clip 24a is connected to the first circumferential end 21a of the gearbox 20, for example, a second U-shaped clip 24b is connected to the second circumferential end 21b of the gearbox 20. Preferably, each U-shaped clip 24a, 24b comprises two ears 24c, each ear having a hole 24d.

[0063] To attach the gearbox 20 to the casing 4', 12, the turbine engine 1 further comprises a suspension arm 25 extending radially from the gearbox 20 to the casing 4', 12. For example, the suspension arm 25 is housed in the hole 24d and / or connected to the inner surface 23b of the housing 22 of the gearbox 20. For example, the suspension arm 25 is a connecting rod. By providing a flexible element in the hole 24d, the flexible element enables the flexible connection of the gearbox 20 to the casing 4', 12, to enable the movement of the gearbox 20. The turbine engine 1 can further comprise an axially extending suspension arm to improve the attachment of the gearbox 20 to the casing 4', 12.

[0064] The gearbox 20 further comprises an inner cavity (not visible) delimited by the housing 22 and a gear train arranged in the inner cavity.

[0065] The inner cavity is located in the housing 22 and extends substantially from the first circumferential end 21a to the second circumferential end 21b.

[0066] Not shown, the gear train comprises a series of intermeshing toothed wheels, each toothed wheel being coaxially mounted around a corresponding shaft. For example, the toothed wheels of the gear train are driven by drawing mechanical power from the low-pressure shaft 8 or the high-pressure shaft 9. The mechanical power taken is transmitted to the gear train by means of a drive shaft coupled to one of the shafts in the gear train.

[0067] The gear train is further coupled to accessory rotors, for example, a main fuel pump (MFP) and / or a permanent magnet alternator (PMA) and / or an air turbine starter (ATS). The gear train also drives a lubrication unit 26 of the turbine engine 1.

[0068] With reference to Figure 4 , the lubrication casings 17, 18 and 19 are supplied with oil by at least one oil circuit C coming from an oil tank 27. The oil circuit C of the turbine engine 1 is a closed circuit comprising an oil supply circuit CI and possibly an oil recovery circuit C2, connected to the lubrication casings 17, 18, 19. The turbine engine 1 can further comprise a hydraulic control circuit connected to a control system for varying the pitch angle of the fixed blades of the fan 2.

[0069] The lubrication unit 26 circulates the oil in the supply circuit CI and the recovery circuit C2, and possibly in the hydraulic control circuit.

[0070] The lubrication unit 26 comprises a device housing 28, at least one feed pump 29 and optionally a recovery pump 30.

[0071] With reference to Figure 3 The device housing 28 is fitted and attached to the housing 22 of the gearbox 20, for example by welding, bolting or flanges 26a to the housing 22. Advantageously, the device housing 28 is attached to the downstream surface 23b of the gearbox 20 at the second circumferential end 24b of the gearbox 20. Thus, preferably, the lubrication unit 26 is located at an angular position around the longitudinal axis X comprised between 3h and 5h, in other words, below the horizontal plane P.

[0072] The device housing 28 has an internal housing in which the feed pump 29 is arranged. The feed pump 29 comprises a rotor arranged in the internal housing of the device housing 28 and coupled to the gear train of the gearbox 20 by a drive shaft 28a extending into the device housing 28 around which the rotor of the feed pump 29 is mounted. The feed pump 29 enables the suction of oil from the tank 27 and the circulation of the sucked oil in the feed circuit Cl.

[0073] According to the requirements of the feed circuit C, the lubrication unit 26 can comprise a plurality of feed pumps 29, each rotor of which is located in the device housing 28.

[0074] The lubrication unit 26 also comprises an oil inlet 31 connected to the feed pump 29 and to the tank 27. The oil inlet 31 is located on the device housing 28.

[0075] With reference to Figure 6 The tank 27 extends angularly around the longitudinal axis X between a first end 32a and an opposite end 32b. The tank 27 extends angularly around the longitudinal axis X between an angular position comprised between 12h and 2h and an angular position comprised between 3h and 4h around the longitudinal axis X. Thus, it should be understood that the first end 32a is located at an angular position comprised between 12h and 2h and the opposite end 32b is located at an angular position comprised between 3h and 4h.

[0076] According to the invention, the tank 27 is located above the lubrication unit 26. Thus, the tank is located at an angular position closer to 12h than the angular position of the lubrication unit 26. Thus, the tank is positioned above the horizontal plane P, in other words, at the top of the turbo engine 1. Thus, the oil can flow by gravity into the lubrication unit 26.

[0077] The tank 27 comprises a casing 33 extending between the end portions 32a, 32b of the tank 27 and an oil outlet 34 formed in the casing 33 and preferably located at the opposite end portion 32b. The oil outlet 34 is connected to the oil inlet 31 of the lubrication unit 26 to feed the supply circuit Cl via the supply pump 29. Advantageously, the oil outlet 34 opens directly into the oil inlet 31 of the lubrication unit 26.

[0078] Advantageously and not shown, advantageously, the casing 33 delimits a first oil compartment (Og (zero gravity) and / or negative g (negative gravity)) and a second oil compartment dedicated, for example, to lubricating the lubrication casings 17, 18, 19 in normal operating conditions of the turbine engine 1, i.e. in positive g conditions. Preferably, the first compartment is located internally (or low) and the second compartment is located externally (or high).

[0079] According to the invention and as can be seen in Figure 7 , Figure 8 and Figure 9 , the tank 27 is located at an angular position closer to 12h than the angular position of the lubrication unit 26, thus above the lubrication unit 26. Thanks to this configuration, the oil can flow by gravity into the lubrication unit 26. This prevents the formation of air bubbles in the tank 27 and the suction of these air bubbles by the supply pump 28, thus optimizing the pressure levels in the oil circuit C and in the hydraulic control circuit. The presence of air bubbles in the hydraulic control circuit can adversely affect the operation of the hydraulic actuators and prevent the proper pitch setting of the stationary vanes.

[0080] Moreover, according to the invention, the tank 27 is directly attached to the equipment housing 28 of the lubrication unit 26. Preferably, the tank 27 is bolted to the equipment housing 28. For example, the opposite end portion 32b of the tank 27 has an attachment collar resting on a seat of the equipment housing 28. Bolts connect the attachment collar to the seat. Alternatively, the tank 27 can be attached to the equipment housing 28 by any attachment means.

[0081] Thanks to the configuration of the invention, in which the tank 27 is directly mounted and attached to the equipment housing 28 of the lubrication unit 26, the piping connecting the oil outlet 34 of the tank 27 to the oil inlet 31 of the lubrication unit 26 can be dispensed with. Thus, the overall dimensions of the assembly formed by the tank 27 and the lubrication unit 26 occupy very little space and can be easily installed in the engine compartment, in particular around the compressor casing 4', even if the diameter of the compressor casing is particularly small compared to the diameter of the fan casing. This means that this assembly can be installed in any type of turbine engine, in particular in turbine engines that do not have a non-ducted fan with a large-diameter fan casing.

[0082] According to the invention and as can be seen in Figure 7The first embodiment of the application illustrated, the turbine engine 1 further comprises connecting arms 35 connecting the gearbox 20 to the tank 27. The connecting arms 35 extend radially. The connecting arms 35 each comprise one end connected to the housing 22 of the gearbox 20, in particular to at least one of the inner surface 23c and / or the downstream surface 23b, and an opposite end connected to the outer shell 33 of the tank 27, for example by welding or additive manufacturing. For example, the connecting arms 35 are connecting rods.

[0083] According to Figure 8 The second embodiment of the application illustrated, the turbine engine 1 further comprises a support 36 radially located between the casing 4', 12 and the tank 27. The support 36 is attached to the tank 27 and to the gearbox 20.

[0084] The support 36 extends angularly around the casing 4', 12 between a first end 36a and an opposite end 36b. Preferably, the support 36 covers an angular sector equal to the angular sector on which the tank 27 extends. Thus, the support 36 carries the tank 27 over its entire circumferential height.

[0085] Advantageously, the support 36 is bolted to the gearbox 20. Preferably, the opposite end 36b is attached to the housing 22 of the gearbox 20, in particular to the downstream surface 21b of the housing 22 and at the second circumferential end 21b of the gearbox 20. Alternatively, the support 36 can be connected to the gearbox 20 by any attachment means.

[0086] The first end 36a is attached to the tank 27, for example by welding, bolting or any other suitable attachment means. The attachment points can be provided along the entire height of the outer shell 33 of the tank 27 to improve the attachment of the support 36 to the tank 27.

[0087] Furthermore, in this embodiment, the support 36 is connected to the casing 4', 12. To this end, in this embodiment, the turbine engine 1 comprises at least one connecting arm 35' connecting the support 36 to the casing 4', 12. The connecting arm 35' extends radially from the support 36 to the casing 4', 12. Advantageously, a plurality of radial connecting arms 35' can connect the support 36 to the casing 4', 12.

[0088] This embodiment enables the tank 27 to be attached even if the stiffness of the tank 27 is not sufficient for the tank to be directly connected to the gearbox 20. Thanks to this solution for attaching the tank 27, the weight of the tank can be significantly reduced.

[0089] In Figure 9In the third embodiment shown, the turbine engine 1 comprises at least one connecting arm 35" connecting the tank 27 to the casing 4', 12. The connecting arm 35" extends radially between the tank 27 and the casing 4', 12. By connecting the tank 27 directly to the casing 4', 12, the forces exerted on the gearbox 20 can be reduced and the weight of the turbine engine 1 can be lightened by cancelling the support 36.

Claims

1. A turbomachine (1) for an aircraft, the turbomachine (1) having a longitudinal axis (X) and comprising: - an annular casing (4', 12) centered on the longitudinal axis (X), - an accessory gearbox (20) located outside and suspended from the casing (4', 12), the accessory gearbox (20) being connected to the casing (4', 12) and comprising: - a housing (22) defining an internal cavity, and - a gear train arranged in the internal cavity, - a lubrication unit (26) comprising: - a device housing (28) fitted and attached to the housing (22) of the accessory gearbox (20), - at least one pump (29) located in the device housing (28) and comprising a rotor coupled to the gear train, and - an oil inlet (31) connected to the pump (29), and - an oil tank (27) comprising an oil outlet (34) connected to the oil inlet (31) of the lubrication unit (26), characterized in that the tank (27) is directly attached to the device housing (28) and is located above the lubrication unit (26) so that oil flows by gravity into the lubrication unit (26).

2. - The turbine engine according to the preceding claim, characterized in that, The tank (27) extends angularly around the longitudinal axis (X) between a first end (32a) located at an angular position comprised between 12h and 2h and an opposite end (32b) located at an angular position comprised between 3h and 4h.

3. The turbine engine of claim 1 or 2, wherein, The housing (22) of the accessory gearbox (20) extends angularly around the longitudinal axis (X) between a first circumferential end (21a) located at an angular position comprised between 9h and 7h and a second circumferential end (21b) located at an angular position comprised between 3h and 5h.

4. The turbine engine of the preceding claim, characterized in that, The housing (22) comprises an upstream surface (23a) and a downstream surface (23b) extending between the first and second circumferential ends (21a, 21b), the device housing (28) being fitted and attached to the downstream surface (23b) at the second circumferential end (21b).

5. The turbine engine of any of the preceding claims, wherein, The turbomachine comprises a radial suspension arm (25) connecting the accessory gearbox (20) to the casing (4', 12).

6. The turbine engine of any of the preceding claims, wherein, The turbomachine comprises a connecting arm (35) connecting the accessory gearbox (20) to the tank (27).

7. The turbine engine of any one of claims 1 to 5, wherein, The turbomachine comprises: - a support (36) arranged radially between the casing (4', 12) and the tank (27) and extending angularly on the casing (4', 12), and - at least one connecting arm (35') connecting the support (36) to the casing (4', 12), the support (36) being attached to the tank (27) and to the accessory gearbox (20).

8. The turbine engine of the preceding claim, characterized in that, The support (36) is bolted to the accessory gearbox (20).

9. The turbine engine of claim 7 or 8 in combination with claim 4, wherein, The support (36) has a first end (36a) attached to the tank (27) and an opposite end (36b) attached at the second circumferential end (21b) of the gearbox (20).

10. The turbine engine of any one of claims 1 to 5, wherein, The turbine engine comprises at least one connecting arm (35'') connecting the tank (27) to the casing (4', 12).

11. The turbine engine of any of the preceding claims, wherein, The tank (27) is bolted to the equipment housing (28).

12. The turbine engine of any one of the preceding claims, wherein, The equipment housing (28) is attached to the housing (22) of the accessory gearbox (20) by welding, bolting or flanging.

13. The turbine engine of any one of the preceding claims, wherein, The turbine engine comprises, from upstream to downstream: - a fan (2), - a low-pressure compressor (3), - a high-pressure compressor (4), - a high-pressure turbine (6) mechanically connected to the high-pressure compressor (4), and - a low-pressure turbine (7) mechanically connected to the low-pressure compressor (3), the casing (4', 12) being located around the high-pressure compressor (4) or axially arranged between the low-pressure compressor and the high-pressure compressor (3, 4).

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