LUBRICATION SYSTEM FOR AN AIRCRAFT TURBOMACHINE

Abstract

The invention relates to a lubrication system (22) for an aircraft turbomachine, comprising: - a shaft, - a guide bearing mounted around the shaft to guide the shaft in rotation, - an oil nozzle (23) adapted to spray oil onto the shaft, and - a scoop (24) for collecting and conveying oil to the bearing, the scoop (24) having an oil inlet (24a) and an oil outlet (24b), the scoop (24) comprising an annular cover (26) mounted coaxially around the shaft and extending from the inlet (24a) to the outlet (24b), the oil flowing in the scoop (24) from upstream to downstream, characterized in that the scoop (24) further comprises: - helical teeth (35) covered by the cover (26) and extending in such a manner Helical around the shaft between the oil inlet (24a) and outlet (24b) so as to guide the oil from the oil inlet (24a) to the oil outlet (24b). Abbreviated figure: Figure 2

Description

Title of the invention: LUBRICATION SYSTEM FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The invention relates to the field of lubrication systems for aircraft turbomachinery.

[0002] The invention relates in particular to lubrication systems for the rotating guide bearings of the shafts of aircraft turbomachinery.

[0003] The invention also relates to aircraft turbomachinery comprising such lubrication systems. Technical background

[0004] An aircraft turbomachine generally extends along and around a longitudinal axis. In the case of a twin-spool, twin-flow turbomachine, it comprises, from front to back, in the direction of gas flow along the longitudinal axis, a low-pressure compressor, a high-pressure compressor, a gas combustion chamber, a high-pressure turbine, and a low-pressure turbine.

[0005] The rotor of the low-pressure compressor is typically connected to the rotor of the low-pressure turbine via a low-pressure shaft. The rotor of the high-pressure compressor, on the other hand, is connected to the rotor of the high-pressure turbine via a high-pressure shaft.

[0006] The turbomachine further comprises a fan located at the front of the low-pressure compressor and driven in rotation about the longitudinal axis by a fan shaft. The fan shaft is connected to the low-pressure shaft.

[0007] The shafts of the turbomachine extend along and around the longitudinal axis of the turbomachine. These shafts are guided in rotation by means of guide bearings.

[0008] Each guide bearing comprises an inner ring mounted around the shaft and an outer ring mounted coaxially around the inner ring. Each guide bearing further comprises a bearing housed in a defined recess between the inner and outer rings. The bearing may be at least one annular row of balls or rollers.

[0009] The turbomachine guide bearings are subjected to particularly high stresses, notably high rotational speeds, high temperatures, and high mechanical loads. In this context, in order to To preserve these guide bearings, it is important to ensure effective lubrication of these guide bearings to reduce the impact of these stresses on the bearings.

[0010] To this end, the turbomachine typically includes a lubrication system for these guide bearings. Such a lubrication system generally includes at least one nozzle that delivers oil to the guide bearing.

[0011] Among lubrication systems, there are systems for direct supply of lubricating oil to the guide bearings and systems for dedicated collection and delivery of the lubricating oil. In direct supply systems, the nozzle sprays lubricating oil directly onto the guide bearing, thus directly lubricating the bearing. In systems with dedicated collection and delivery, these typically include a scoop that collects and delivers the lubricating oil sprayed by the nozzle to the guide bearing. For this purpose, the inner ring of the guide bearing typically includes at least one radial groove that opens into the bearing housing and communicates smoothly with the scoop.The radial groove in the bearing allows the lubricating oil to penetrate the guide bearing housing by centrifugal force.

[0012] Given the particularly high rotational speeds of the bearing, direct oil supply systems prove inefficient, and systems with dedicated collection and delivery are preferred. These systems also ensure efficient lubrication by limiting the required lubricating oil flow and reducing oil heating due to shear. This therefore limits the thermal stresses on the guide bearings and increases their service life.

[0013] Among scoops, there are axial scoops and radial scoops. Axial scoops refer to scoops that collect and convey lubricating oil sprayed from a nozzle whose axis lies in a plane passing substantially through the longitudinal axis. Conversely, radial scoops refer to scoops that collect and convey lubricating oil sprayed from a nozzle whose axis extends in a plane perpendicular to the longitudinal axis.

[0014] Axial scoops have the significant advantage of offering better lubricating oil recovery efficiency compared to radial scoops, recovery efficiency being the ratio of the oil flow rate recovered by the scoop to the oil flow rate of the nozzle. Indeed, the recovery efficiency of an axial scoop reaches 90%, while the recovery efficiency of a radial scoop ranges between 50% and 80%.

[0015] Radial scoops, however, have the advantage of being more compact than axial scoops, which facilitates their integration into the turbomachine. Indeed, the axial scoop operates on a difference between the radius The internal diameter of the guide bearing and the internal radius of the scoop's inlet must be positive and sufficient to create manometric pressure to ensure oil circulation to the guide bearing. Therefore, it is generally desirable to increase the internal diameter of the inner ring, which increases the overall size of the guide bearing and makes the radial scoop solution less attractive, although still largely effective.

[0016] Therefore, there is a need to provide a lubrication system for a guide bearing of an aircraft turbomachine, which has high recovery efficiency, while being easily integrable into the turbomachine, i.e. compatible with a large turbomachine footprint. Summary of the invention

[0017] To this end, the invention proposes a lubrication system for an aircraft turbomachine, the lubrication system comprising:

[0018] - a shaft extending along and around a longitudinal axis, a guide bearing mounted around the shaft to guide the shaft in rotation around the longitudinal axis,

[0019] - an oil jet suitable for projecting oil onto the shaft, and

[0020] - a scoop for collecting and conveying oil to the bearing, the scoop featuring an oil inlet located on the oil jet side and an oil outlet located on the bearing side, the scoop comprising an annular cover mounted coaxially around the shaft and extending from the inlet to the outlet, the oil flowing in the scoop upstream to downstream from the inlet to the outlet.

[0021] The lubrication system is remarkable in that the scoop further comprises:

[0022] - helical teeth covered by the cover and extending in a manner helical around the shaft between the oil inlet and outlet so as to guide the oil from the oil inlet to the oil outlet.

[0023] According to the invention, the scoop is composed of teeth which are arranged in a helix around the shaft and inside the cover.

[0024] Such helical teeth mounted around the shaft are driven in rotation by the shaft. These helical teeth, rotating around the longitudinal axis, generate an upstream to downstream flow of oil within the cover and thus guide the oil projected by the nozzle into the scoop. The oil is thus drawn into the scoop from the inlet to the outlet.

[0025] Thanks to such a scoop, it is possible to eliminate the need for a static pressure differential within the scoop to draw the oil into the scoop. Therefore, it is no longer necessary to ensure a sufficient positive difference between the inner radius of the bearing and the inner radius of the scoop inlet.

[0026] Thanks to the invention, it is therefore possible to guarantee efficient oil recovery, without increasing the size of the turbomachine.

[0027] The invention may comprise one or more of the following features, taken individually or in combination with each other:

[0028] - the cover includes a first annular rib extending radially towards the interior with respect to the longitudinal axis, the first rib being in particular located at the level of the entrance,

[0029] - the scoop includes a second annular rib extending radially towards the exterior with respect to the longitudinal axis, the second rib being in particular located at the level of the entrance,

[0030] - the second rib is axially offset downstream relative to the first rib,

[0031] - each tooth has a helical upstream face and a helical downstream face, the face the upstream side of each tooth being inclined upstream relative to a plane perpendicular to the longitudinal axis,

[0032] - the teeth are separated from each other by an axial distance that decreases in the direction of downstream,

[0033] - the lid has a truncated conical shape that flares out towards the upstream end,

[0034] - the cover comprises an annular internal surface which extends between the inlet and the outlet, the internal surface at the inlet widening downstream,

[0035] - the teeth are carried or formed by an annular ring which is mounted coaxially around the shaft and which is rotationally fixed to the shaft,

[0036] - the ring comprises at least two half-rings assembled around the shaft,

[0037] - the teeth define helical oil guide grooves between each other fluidic communication respectively with axial grooves of the shaft, these axial grooves being intended to guide the oil from the scoop outlet to the guide bearing,

[0038] - the scoop comprises between two and ten teeth, advantageously between two and six teeth, and preferably four teeth

[0039] - among the teeth, an upstream tooth is located furthest upstream, the upstream tooth comprising at least one guide blade extending axially to the inlet,

[0040] - the nozzle comprises an ejection nozzle having an inclined spray axis at an angle a with respect to the longitudinal axis as measured in a plane containing the longitudinal axis and the spray axis, the angle a being for example between 0° and 60°.

[0041] The invention also relates to a turbomachine. The turbomachine is remarkable in that it includes a lubrication system according to any one of the preceding characteristics. Brief description of the figures

[0042] Other features and advantages will become apparent from the following description of non-limiting embodiments of the invention with reference to the accompanying drawings in which:

[0043] [Fig. 1] is a schematic longitudinal cross-sectional representation of an aircraft turbomachine,

[0044] Figure 2 is a longitudinal cross-sectional view of a lubrication system comprising a scoop according to the invention.

[0045] [Fig. 2a] is a top cross-sectional view of the lubrication system,

[0046] [Fig.3] is a perspective view of a cover according to an embodiment of the invention and which can be fitted to the scoop of [Fig.2],

[0047] [Fig.4] is a longitudinal cross-sectional view of a lubrication system according to the invention comprising the cover of [Fig.3],

[0048] Figure 5 is a longitudinal cross-sectional view of a scoop according to one embodiment of the invention,

[0049] Figure 6 is a longitudinal cross-sectional view of a scoop according to another embodiment of the invention,

[0050] Figure 7 is a perspective view of a portion of the lubrication system comprising a scoop being mounted around the shaft, according to another embodiment of the invention.

[0051] Figure 8 is a perspective view of a portion of the scoop according to the invention,

[0052] [Fig. 9] is a longitudinal cross-sectional view of a scoop according to another method of realization of the invention,

[0053] [Fig. 10] is a longitudinal cross-sectional view of a scoop according to another embodiment of the invention,

[0054] [Fig.1 1] is a perspective view of part of the scoop according to another embodiment of the invention. Detailed description of the invention

[0055] An example of an aircraft turbomachine 1 to which the invention can be applied is shown in [Fig. 1].

[0056] The turbomachine 1 is, for example, a turbofan engine. The turbomachine 1 may have any other architecture and may, for example, take the form of a turboprop, a turboshaft engine, or an auxiliary power unit, known by the English acronym APU for "Auxiliary Power Unit".

[0057] The turbomachine 1 is modular. It comprises a plurality of modules assembled together.

[0058] The turbomachine 1 extends along a longitudinal axis X. A gas flow F flows into the turbomachine 1.

[0059] For the purposes of the present invention, the terms "front" and "rear" are understood in relation to the direction of flow of the gas flow F in the turbomachine 1. The gas flow F flows in particular from left to right in Figures 1 and 2.

[0060] Furthermore, the terms "longitudinal", "longitudinally", "radial", "radially" are understood in relation to the longitudinal axis X of the turbomachine 1. The terms "external", "internal" are understood in relation to the distance from the longitudinal axis X along a radial axis perpendicular to the longitudinal axis X.

[0061] The turbomachine 1 comprises, from front to back, a blower 2, 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.

[0062] 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 composed of a plurality of stages, each comprising a bladed wheel.

[0063] The gas flow F passes through the blower 2 and splits into a primary air flow Fl passing through a primary stream v1 and a secondary air flow F2 passing through a secondary stream v2 surrounding the primary stream v1. The primary air flow Fl passes through the low-pressure compressor 3 and the high-pressure compressor 4. The compressed primary air flow Fl then passes through the combustion chamber 5 where it is mixed with fuel. The combustion gases thus pass through the high-pressure turbine 6 and the low-pressure turbine 7. The energy of the gases is transformed by the turbine rotor 7a of the low-pressure turbine 7 into mechanical energy, which drives the low-pressure shaft 8 and, consequently, the low-pressure compressor 3.

[0064] The fan 2 comprises a rotating disk about the longitudinal axis X and blades 2a carried by the disk and evenly distributed about the longitudinal axis X. In the example of [Fig. 1], the fan 2 is surrounded by a fan housing 2b. The fan 2 is of the enclosed type. The fan housing 2b carries a nacelle 2c and together they define a fan compartment 2d.

[0065] According to another example not shown, the blower 2 is of the non-faired type.

[0066] The turbomachine 1 further comprises an inter-compressor housing 8 arranged axially between the low-pressure compressor 3 and the high-pressure compressor 4.

[0067] The turbomachine 1 may further include an inlet housing 9. The inlet housing 9 is arranged axially between the blower 2 and the low-pressure compressor 3.

[0068] The turbomachine 1 may further include an inter-turbine casing 10. The inter-turbine casing 10 is arranged axially between the high-pressure turbine 6 and the low-pressure turbine 7.

[0069] The turbomachine 1 further comprises at least one drive shaft 11, 12, 13 of at least one rotor 2, 3a, 4a, 6a, 7a of the turbomachine 1.

[0070] In particular, 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 11. They form a low pressure body.

[0071] 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 12. They form a high-pressure body.

[0072] The low pressure shaft 11 and high pressure shaft 12 are centered on the longitudinal axis X and are free to rotate about the longitudinal axis X. The high pressure shaft 12 is arranged coaxially around the low pressure shaft 11.

[0073] The fan disk 2 is driven in rotation by a fan shaft 13. In the example described, and therefore optionally, the fan shaft 13 is connected to the low-pressure shaft 11 via a speed reducer 14. The speed reducer 14 is of the mechanical type. For example, it is an epicyclic or planetary gear train.

[0074] The speed reducer 14 allows the blower shaft 13 to be driven at a rotational speed lower than the rotational speed of the low-pressure shaft 11. This allows the dilution ratio of the turbomachine 1 to be increased.

[0075] Each shaft 11, 12, 13 comprises a cylindrical body 15 centered on the longitudinal axis X. Each shaft 11, 12, 13 further comprises at least one axial groove 16. Each shaft 11, 12, 13 preferably comprises a plurality of axial grooves 16, for example, between two and six axial grooves 16 distributed around the longitudinal axis X. The axial grooves 16 are, for example, regularly distributed around the longitudinal axis X. Each axial groove 16 extends in a direction parallel to the longitudinal axis X. Each axial groove 16 has a cross-section, for example, rectangular. Each axial groove 16 is formed on the cylindrical body 15, in particular on an external annular face of the cylindrical body 15.

[0076] Advantageously, each shaft 11, 12, 13 further comprises at least one shoulder 17a, 17b. Preferably, each shaft 11, 12, 13 comprises first and second annular shoulders 17a, 17b. Each shoulder 17a, 17b is formed on the cylindrical body 15. Each shoulder 17a, 17b is centered on the longitudinal axis X.

[0077] Preferably, the first shoulder 17a is sectorized. The sectors of the first shoulder 17a are separated from each other by the axial grooves 16.

[0078] The second shoulder 17b is annular and extends around the longitudinal axis X.

[0079] The turbomachine 1 further includes at least one bearing 18 for guiding the rotation of at least one shaft 11, 12, 13 of the turbomachine 1. The bearing 18 is mounted coaxially around at least one shaft 11, 12, 13 of the turbomachine 1.

[0080] In particular, the blower shaft 13 is guided in rotation by a first bearing 18a and advantageously a second bearing 18b. The first and second bearings 18a, 18b are arranged radially between the blower shaft 13 and the inlet housing 9.

[0081] The low-pressure shaft 11 is guided in rotation by at least a third and fourth bearing 18c, 18d. The third bearing 18c is arranged radially between the inlet housing 9 and the low-pressure shaft 11. The fourth bearing 18d is arranged radially between the inter-compressor housing 8 and the low-pressure shaft 11.

[0082] The high-pressure shaft 12 is guided in rotation by a fifth bearing 18e. The fifth bearing 18e is, for example, arranged radially between the high-pressure shaft 12 and the inter-turbine housing 10.

[0083] The low-pressure shaft 11 can be guided in rotation downstream by a sixth bearing 18f arranged radially between a downstream end of the low-pressure shaft 11 and the inter-turbine housing 10 for example.

[0084] As more clearly seen in [Fig. 2], each bearing 18 comprises an inner ring 19 mounted around the shaft 11, 12, 13 and an outer ring 20 situated coaxially around the inner ring 19. The inner and outer rings 19, 20 are annular and centered on the longitudinal axis X. The inner and outer rings 19, 20 define between them an annular housing 21. Each bearing 18 further comprises a bearing 21a located in the annular housing 21. The bearing 21a is, for example, at least one annular row of balls or rollers.

[0085] The inner ring 19 comprises at least one flow channel 19a which may open into the annular housing 21. The channel 19a advantageously extends radially. Preferably, the inner ring 19 comprises two flow channels 19a extending, for example, radially and each opening into the annular housing 21.

[0086] The inner ring 19 has a first internal radius ri.

[0087] Depending on the configuration of the turbomachine 1, the number of bearings 18 may vary.

[0088] The bearings 18 are lubricated by oil to ensure their proper operation and their longevity, in particular in view of the mechanical stresses to which the bearings 28 of these bearings 18 are subjected, such as rotational speeds, high temperatures and significant mechanical loads.

[0089] For this purpose, the turbomachine 1 includes a lubrication system 22 for the bearings 18.

[0090] The lubrication system 22 is a dedicated collection and conveying lubrication system. Such a lubrication system 22 differs from direct feed systems, in particular in that it includes a scoop 24.

[0091] With reference to [Fig.2], the lubrication system 22 therefore includes a nozzle 23 and a scoop 24 for collecting and conveying oil to the bearing 18.

[0092] The nozzle 23 allows oil to be projected onto the shaft 11, 12, 13. The nozzle 23 includes an ejection nozzle 25 which extends radially towards the inside of the turbomachine 1. The ejection nozzle 25 is oriented in the direction of the shaft 11, 12, 13. In particular, the ejection nozzle 25 has a spray axis which may be located outside a plane passing through the longitudinal axis X.

[0093] As more clearly seen in [Fig. 2a], the spray axis of the ejection nozzle 25 is inclined at an angle α with respect to the longitudinal axis X as measured in a plane containing the longitudinal axis X and the spray axis. The angle α being, for example, between 0° and 60°.

[0094] The scoop 24 is of axial type, in reference to the configuration of the ejection nozzle 25, as opposed to radial scoops which refer to scoops which allow the recovery of oil delivered by a nozzle whose nozzle axis is perpendicular to the longitudinal axis X.

[0095] The scoop 24 is located axially between the first and second shoulders 17a, 17b.

[0096] The scoop 24 includes an oil inlet 24a and an oil outlet 24b.

[0097] According to the invention, the oil flows through the scoop 24 from the inlet 24a to the outlet 24b.

[0098] In the present invention, the terms "upstream" and "downstream" extend relative to the flow of oil in the scoop 24 from the inlet 24a to the outlet 24b. The term "upstream" therefore refers to an element located relatively closer to the inlet 24a, and the term "downstream" refers to an element located relatively closer to the outlet 24b. In [Fig. 2], the oil flows from right to left in the scoop 24.

[0099] The inlet 24a is located on the side of the nozzle 23 and the outlet is axially opposite to the inlet 24a and is located on the side of the guide bearing 15. The ejection nozzle 25 of the nozzle 23 is thus oriented towards the inlet 24a of the scoop 24. The angled orientation of the oil jet generated by the angle α of the spray axis of the ejection nozzle 25 improves the recovery efficiency of the scoop 24.

[0100] The inputs and outputs 24a, 24b are annular. They are axially oriented. In other words, the inputs and outputs 24a, 24b each have an axis parallel to the longitudinal axis X.

[0101] The inlet 24a of the scoop advantageously has a second internal radius r2. The second internal radius r2 of the scoop is greater than the first internal radius rl of the inner ring 19 of bearing 18. According to this advantageous embodiment of the invention, the difference Ar between the first and second internal radii r1, r2 is therefore negative. This makes it possible to reduce the overall size of the turbomachine 1 by reducing the internal radius of bearing 18.

[0102] The scoop 24 further includes a cover 26 mounted coaxially around the shaft 11, 12, 13. The cover 26 is located axially between the first and second shoulders 17a, 17b.

[0103] The cover 26 is annular and centered on the longitudinal axis X. The cover 26 extends axially between an annular upstream end 27 and an annular downstream end 28. The upstream end 27 is located at the inlet 24a of the scoop 24 and the downstream end 28 is located at the outlet 24b of the scoop 24.

[0104] The cover 26 further comprises an annular wall 29 and an internal space 30 delimited by the annular wall 29.

[0105] The annular wall 29 is centered on the longitudinal axis X and extends between the upstream and downstream ends 27, 28. It has an internal surface 31 and an external surface 32.

[0106] The cover 26 may further comprise a radial annular wall 29a located at the downstream end 28 of the cover 26. The first shoulder 17a bears against an upstream face of the radial annular wall 29a of the cover 26. Such a feature allows the cover 26 to be axially locked.

[0107] According to a particularly advantageous embodiment of the invention illustrated in Figures 3 and 4, the cover 26 has a frustoconical shape that flares upstream. In this embodiment, the upstream end 27 has an internal diameter greater than the internal diameter of the downstream end 28. Thus, the internal diameter of the cover 26 decreases downstream. Consequently, the internal surface 31 of the cover 26 is inclined towards the inside of the turbomachine 1 in the downstream direction. The frustoconical shape of the cover 26 facilitates the guidance of the oil in the scoop 24.

[0108] According to a particularly advantageous embodiment of the invention, also illustrated in Figures 5 and 6, the cover 26 may further comprise a first annular rib 33 extending radially inwards towards the turbomachine 1. The first annular rib 33 extends radially inwards from the internal surface 31 of the cover 26. The first annular rib 33 is preferably formed on the upstream end 27 of the cover 26 and thus on the inlet 24a of the scoop 24. This first rib 33 facilitates the entry of oil into the scoop 24 and minimizes oil losses at the inlet of the scoop 24.

[0109] According to a particularly advantageous embodiment of the invention, the internal surface 31 comprises an inlet portion 31a which flares downstream, therefore towards the outlet 24b of the scoop 24. Thus, the inlet portion 31a of the internal surface 31 of the cover 26 extends outwards and towards the downstream end 28 from the upstream end 24a of the cover 26. Preferably, this inlet portion 31a is located in a plane inclined with respect to the longitudinal axis X at an angle, for example, between 0° and 45°. This feature facilitates the flow of oil into the scoop 24 from upstream to downstream by centrifugal force.

[0110] According to the invention, the scoop 24 may further comprise a ring 34 mounted coaxially around the shaft 11, 12, 13. The ring 34 is free to rotate about the longitudinal axis X. It is fixed in rotation to the shaft 11, 12, 13.

[0111] The ring 34 is annular and centered on the longitudinal axis X. It is located inside the cover 26. The ring 34 is thus located axially between the first and second shoulders 17a, 17b.

[0112] According to an embodiment illustrated in [Fig. 7], the ring 34 can be multi-part. In particular, the ring 34 can comprise two half-rings 34a, 34b assembled around the shaft 11, 12, 13. Each half-ring 34a, 34b thus extends over an angular sector around the longitudinal axis X of 180°.

[0113] The ring 34 may comprise more than two ring sectors.

[0114] According to the invention, and as can be seen for example also in [Fig.8], the scoop 24 further comprises helical teeth 35 mounted around the shaft 11, 12, 13. The teeth 35 are rotationally movable around the longitudinal axis X by being rotationally fixed to the shaft 11, 12, 13.

[0115] The teeth 35 of the scoop 24 according to the invention allow the oil to be guided in translation along the longitudinal axis X from the inlet 24a of the scoop 24 to the outlet 24b of the scoop 24.

[0116] The teeth 35 are located in the cover 26 and extend between the oil inlet 24a and outlet 25. In particular, the teeth 35 are carried or formed by the ring 34.

[0117] For example, the scoop 24 comprises between two and ten teeth 35, advantageously between two and six teeth 35, and preferably four teeth 34.

[0118] The teeth 35 have a helix angle of, for example, between 10° and 30°.

[0119] The teeth 35 define helical grooves 36 between themselves. Each helical groove 36 is in fluidic communication with an axial groove 16 of the shaft 11, 12, 13. In particular, each helical groove 36 opens into the upstream end 16a of an axial groove 16. Each axial groove 16 thus has its own oil supply circuit formed by the helical grooves 36. This feature makes it possible to uniformly distribute the oil flow in the axial grooves 16 in order to effectively lubricate the bearings 18.

[0120] Adjacent teeth 35 are separated from each other by an axial distance d measured along a direction parallel to the longitudinal axis X. The axial distance d separating the teeth 35 may be constant or variable. According to an advantageous embodiment of the invention illustrated in particular in [Fig. 9], the axial distance d is variable. In particular, this axial distance d decreases from upstream to downstream. According to this embodiment, the teeth 35 located upstream are thus separated by a first axial distance d1 greater than a second axial distance d2 separating the teeth 35 located downstream. This improves the amount of oil entering the scoop 24 while stabilizing the level of centrifuged oil within the scoop 24. Also, the variable axial distance d allows the oil to circulate in the scoop 24 while providing a scoop 24 with an inlet radius greater than the maximum radius of the helical grooves 36.

[0121] Each tooth 35 extends radially outwards, for example from the ring 34. Each tooth 35 has a head 35a, an upstream face 35b or upstream flank, and a downstream face 35c or downstream flank.

[0122] According to an advantageous embodiment of the invention illustrated in [Fig. 10], the upstream face 35b of each tooth 35 is inclined downstream with respect to a plane perpendicular to the longitudinal axis X. For example, the upstream face 35b of each tooth 35 is inclined with respect to this plane at an angle between 0° and 20°. This feature promotes the flow of oil into the scoop 24 by centrifugal force from upstream to downstream.

[0123] According to an advantageous embodiment of the invention illustrated in [Fig. 11], the upstream tooth 35, referred to as the upstream tooth 37, comprises at least one oil guide blade 38 in the scoop 24. Advantageously, the upstream tooth 37 comprises a plurality of blades 38 distributed around the longitudinal axis X. Each blade 38 has a free upstream end 38a which extends substantially axially to the inlet 24a of the scoop 24 from the upstream tooth 37. This feature improves the guidance of the oil in the helical groove 36 delimited by the upstream tooth 37.

[0124] According to an advantageous embodiment of the invention, for example illustrated in [Fig. 10], the scoop 24 may include a second annular rib 39. The second rib 39 extends radially outwards and is, for example, located on the side of the inlet 24a of the scoop 24. Such a feature further facilitates the entry of oil into the scoop 24.

[0125] In particular, the second rib 39 is carried or formed on the ring 34. The first and second ribs 33, 39 are thus radially opposed.

[0126] Preferably, the first and second ribs 33, 39 are axially offset, with the second rib 39 located downstream of the first rib 33. A This feature helps to keep the oil in scoop 24 and to limit the risk of leakage.

[0127] Thanks to the scoop 24 of the invention, in particular the teeth 36 mounted around the shaft 11, 12, 13, it is possible to generate an oil flow in the scoop 24 that supplies oil to the bearing 18 located downstream of the scoop 24. It is therefore possible to eliminate a positive internal radius difference Ar which generally increases the size of the turbomachine 1. This facilitates the integration of the scoop 24 and the bearing 18 into the turbomachine 1.

[0128] Thanks to the scoop 24 of the invention, it is possible to improve the quantity of oil entering the scoop 24. In particular, the oil inlet surface is increased.

[0129] Also, thanks to the first and second ribs 33, 39 and their axial offset, as well as the configuration of the inlet portion 31a of the cover 26, the centrifugal effect of the scoop 24 is improved and the risk of leakage of oil captured by the scoop 24 is reduced.

[0130] Also, thanks to the variability of the axial distance d separating the teeth 35 from the scoop 24, the quantity of oil captured is further improved.

[0131] Also, thanks to the inclination of the teeth 35, the flow of oil from upstream to downstream by centrifugal effect is improved.

[0132] This improves the lubrication efficiency of bearing 18, thus improving its service life.

[0133] Also, thanks to the improvement of the oil flow in the scoop 24 according to the invention, it is possible to simplify the configuration of the nozzle 23. In particular, it is possible to provide nozzles 23 whose diameter and length of the nozzle can be contained within larger ranges of value and whose position of this nozzle relative to the scoop 24 is more flexible, facilitating its integration.

Claims

Demands

1. Lubrication system (22) for an aircraft turbomachine (1), the lubrication system (22) comprising: - a shaft (11, 12, 13) extending along and around a longitudinal axis (X), a guide bearing (18, 18a, 18b, 18c, 18d, 18e, 18f) mounted around the shaft (11, 12, 13) to guide the shaft (11, 12, 13) in rotation around the longitudinal axis (X), - an oil nozzle (23) capable of projecting oil onto the shaft (11, 12, 13), and - a scoop (24) for collecting and conveying oil to the bearing (18, 18a, 18b, 18c, 18d, 18e, 18f), the scoop (24) having an oil inlet (24a) located on the side of the oil nozzle (23) and an oil outlet (24b) located on the side of the bearing (18), the scoop (24) comprising an annular cover (26) mounted coaxially around the shaft (11, 12, 13) and extending from the inlet (24a) to the outlet (24b), the oil flowing in the scoop (24) from upstream to downstream from the inlet (24a) to the outlet (24b),characterized in that the scoop (24) further comprises: - helical teeth (35) covered by the cover (26) and extending helically around the shaft (11, 12, 13) between the oil inlet (24a) and outlet (24b) so as to guide the oil from the oil inlet (24a) to the oil outlet (24b).

2. Lubrication system according to the preceding claim, characterized in that the cover (26) comprises a first annular rib (33) extending radially inwards with respect to the longitudinal axis (X), the first rib (33) being in particular located at the level of the inlet (24a).

3. Lubrication system according to any one of the preceding claims, characterized in that the scoop (24) comprises a second annular rib (39) extending radially outwards from the longitudinal axis (X), the second rib (39) being in particular located at the inlet (24a).

4. Lubrication system according to claims 2 and 3, characterized in that the second rib (39) is axially offset downstream relative to the first rib (33).

5. A lubrication system according to any one of the preceding claims, characterized in that each tooth (35) has a upstream face (35b) helical and a downstream face (35c) helical, the upstream face (35b) of each tooth (35) being inclined upstream with respect to a plane perpendicular to the longitudinal axis (X).

6. Lubrication system according to any one of the preceding claims, characterized in that the teeth (35) are separated from each other by an axial distance (d) which decreases in the downstream direction.

7. Lubrication system according to any one of the preceding claims, characterized in that the cover (26) has a frustoconical shape which flares upwards.

8. Lubrication system according to any one of the preceding claims, characterized in that the cover (26) comprises an annular internal surface (31) extending between the inlet (24a) and the outlet (24b), the internal surface (31) at the inlet (24a) flaring out in the downstream direction.

9. Lubrication system according to the preceding claim, characterized in that the teeth (35) are carried or formed by an annular ring (34) which is mounted coaxially around the shaft (11, 12, 13) and which is rotationally fixed to the shaft (11, 12, 13).

10. Lubrication system according to the preceding claim, characterized in that the ring (34) comprises at least two half-rings (34a, 34b) assembled around the shaft (11, 12, 13).

11. Lubrication system according to any one of the preceding claims, characterized in that the teeth (35) define between themselves helical oil guide grooves (36) in fluidic communication respectively with axial grooves (16) of the shaft (11, 12, 13), these axial grooves (16) being intended to guide the oil to the guide bearing (18, 18a, 18b, 18c, 18d, 18e, 18f) from the outlet (24b) of the scoop (24).

12. Lubrication system according to any one of the preceding claims, characterized in that the scoop (24) comprises between two and ten teeth (35), advantageously between two and six teeth (35), and preferably four teeth (35).

13. Lubrication system according to any one of the preceding claims, characterized in that among the teeth (35), an upstream tooth (37) is located furthest upstream, the upstream tooth (37) comprising at least one guide blade (38) extending axially to the inlet (24a).

14. Lubrication system according to any one of the preceding claims, characterized in that the nozzle (23) comprises an ejection nozzle (25) having a spray axis inclined at an angle α with respect to the longitudinal axis (X) as measured in a plane containing the longitudinal axis (X) and the spray axis, the angle α being for example between 0° and 60°.

15. Turbomachine (1) for an aircraft, characterized in that it comprises a lubrication system (22) according to any one of the preceding claims.

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