MECHANICAL SPEED REDUCER

Abstract

Mechanical reducer (6) comprising an input shaft (3), a sun gear (7), a crown (9), satellites (8), and a system (20) for lubricating at least a part of the reducer (6), the input shaft (3) comprising a first elastically deformable section (18) which comprises two annular walls (18a, 18b) which define between them at least one passage (22) for circulating oil which is in fluid communication with orifices (24) formed in the first section (18) and configured to project oil in operation for the purpose of supplying said lubrication system (20). Figure for the abstract: Figure 6

Description

Title of the invention: MECHANICAL SPEED REDUCER Technical field of the invention

[0001] The present invention relates to a mechanical speed reducer, as well as an aircraft turbomachine or a device for driving at least one wheel of an aircraft landing gear comprising such a reducer. Technical background

[0002] The role of a mechanical reducer is to modify the speed and torque ratio between the input axis and the output axis of a mechanical system.

[0003] In the remote field of aircraft turbomachines, it is known to use a mechanical reducer to ensure power transmission between two rotating mechanical shafts.

[0004] There are many types of reducers, for example differential, planetary, epicycloidal, with intermediate lines, with series reduction stages, etc.

[0005] In the state of the art of dual-flow turbomachines, the reducers are of the planetary or epicyclic type. Such a reducer comprises a central pinion, called a sun gear, a crown gear and pinions called satellites, which are engaged between the sun gear and the crown gear. The satellites are held by a frame called a planet carrier. The sun gear, the crown gear and the planet carrier are planetary gears because their axes of revolution coincide with the longitudinal axis of the turbomachine. The satellites each have a different axis of revolution equally distributed over the same operating diameter around the axis of the planetary gears. These axes are parallel to the longitudinal axis of the turbomachine.

[0006] There are several reducer architectures. In other similar applications, there are so-called differential or "compound" architectures.

[0007] - On a planetary reducer, the planet carrier is fixed and the crown constitutes the output shaft of the device which rotates in the opposite direction to the solar.

[0008] - On an epicyclic reducer, the crown is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar.

[0009] - On a differential reducer, no element is fixed in rotation. The crown rotates in the opposite direction of the solar and the satellite carrier.

[0010] The reducers can be composed of one or more meshing stages. This meshing is ensured in different ways such as by contact, by friction or even by magnetic fields.

[0011] In the present application, the term "stage" or "teeth" means at least one series of meshing teeth with at least one series of complementary teeth. A dentition can be internal or external.

[0012] The input shaft of the reducer is generally tubular and has one end axially engaged in the sun gear and coupled to the latter for its rotational drive.

[0013] To limit the risk of misalignment of the gear teeth, it is known to provide flexibility on the input shaft. This flexibility can be obtained in different ways. A first solution consists of providing a bellows-shaped section on the input shaft. The bellows shape gives the section a capacity for elastic deformation and therefore flexibility. Another solution consists of providing a section of the typc / Zev coupling on the shaft. This connection comprises two radial fixing flanges which are fixed together and which also give a certain flexibility to the section, in particular by spacing the flanges.

[0014] Due to its particular shape, the flexible or elastically deformable section of an input shaft is relatively bulky in the radial direction.

[0015] A mechanical reducer must be lubricated and is thus equipped with a lubrication system which must be supplied with oil. For this, the reducer can be equipped with an impeller which comprises an annular mouth oriented radially inwards and inside which oil is sprayed by means of nozzles. These nozzles must be surrounded by the impeller and its mouth to allow the impeller to be supplied. The nozzles are then inserted radially inside the impeller. However, the integration of the assembly is not always possible or easy because the nozzles can hinder the installation of the flexibility section of the input shaft, or conversely the flexibility section of the input shaft can hinder the installation of the nozzles.

[0016] The invention provides a solution to at least some of these problems, which is simple, effective and economical. Summary of the invention

[0017] The invention relates to a mechanical reducer comprising:

[0018] - an input shaft,

[0019] - a mobile solar rotating around an X axis and comprising at least one tooth external,

[0020] - a crown extending around the X axis and comprising at least one toothing internal,

[0021] - satellites distributed around the X axis and meshed respectively with the teeth of the sun and the corona, the satellites being mobile in rotation around Y axes parallel to the X axis, and

[0022] - a lubrication system for at least part of the reducer,

[0023] the input shaft being tubular and having one end axially engaged in the sun and coupled to the latter for its rotational drive, the input shaft having a flexible section which comprises two annular walls which face each other axially, these annular walls having their radially external ends which are connected together and their radially internal ends which are connected to the rest of the shaft,

[0024] characterized in that the annular walls of the flexible section define axially between them at least one oil circulation passage which is in fluid communication with orifices formed in the flexible section and configured to project oil in operation for the purpose of supplying said lubrication system.

[0025] The invention is particularly advantageous because it makes it possible to supply the reducer with oil via its input shaft and therefore to give the input shaft a lubrication function that it did not have until now. This is made possible by the flexible section of the input shaft which comprises annular walls making it possible to channel the oil and guide it radially outwards. The oil is then conveyed to oil projection orifices which are formed in this flexible section and which make it possible to project oil, for example into the intake opening of the impeller as mentioned above. The nozzles of the prior art are then no longer necessary and can be removed, which makes it possible to clear this area and to provide an increase in the external diameter of the flexible section for example.

[0026] The invention is compatible with a single-stage or multi-stage reducer. It is also compatible with an epicyclic, planetary or differential. It is also compatible with teeth of any type (straight, helical, chevron, etc.). The invention is furthermore compatible with a planet carrier of the monobloc type or of the cage and cage carrier type. The solution proposed below is compatible with any type of satellite bearing, whether it is composed of rolling elements, a hydrodynamic bearing, etc. These different types of reducer are well known to those skilled in the art.

[0027] The reducer according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another:

[0028] — the flexible section is elastically deformable; - the first section is formed from a single piece and the annular walls are axially spaced from each other to define between them said oil circulation passage, which is annular, these annular walls being connected at their external peripheries by an annular connecting wall which comprises said orifices;

[0029] — the annular walls are parallel;

[0030] — the annular walls are inclined in particular to optimize the circulation of oil; - the first section forms a portion of the shaft bellows or is part of a shaft bellows; - the first section is formed by two flanges respectively forming the two annular walls, these two flanges being fixed to each other by screws which axially pass through holes in the flanges, lunules being formed in at least one of the annular faces opposite the flanges to form said oil circulation passages which form at their radially external ends said orifices; - the first section is located radially inside the solar, the orifices being configured to spray lubricating oil from the solar; - the first section is located radially inside an impeller of said lubrication system, the orifices being configured to project oil into an annular mouth of the impeller which is oriented radially inwards with respect to the X axis; - the shaft comprises a second section, at a distance from the first section, this second section forming a centripetal scoop and comprising radial through-holes for the passage of oil; - the reducer further comprises at least one oil jet located radially outside the shaft and configured to spray oil radially inside the shaft through said ports; - the or each oil nozzle comprises an oil projection axis which is inclined relative to a radial direction with respect to the X axis.

[0031] The present invention also relates to an aircraft turbomachine, comprising a mechanical speed reducer as described above.

[0032] The present invention also relates to a device for driving at least one wheel of an aircraft landing gear, this device comprising a mechanical speed reducer as described above. Brief description of the figures

[0033] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0034] [Fig-1] [Fig.l] is a half schematic view in axial section of a turbomachine aircraft,

[0035] [Fig.2] [Fig.2] is a half schematic view in axial section of a speed reducer,

[0036] [Fig.3] [Fig.3] is a half schematic view in axial section of a reducer and its lubrication system,

[0037] [Fig.4] [Fig.4] is a schematic axial sectional view of a prior art reducer;

[0038] [Fig.5] [Fig.5] is a partial schematic view in axial section of a reducer according to a first embodiment of the invention;

[0039] [Fig.6] [Fig.6] is a partial schematic perspective view of the reducer of [Fig.5];

[0040] [Fig.7] [Fig.7] is a partial schematic view in axial section of a reducer according to a second embodiment of the invention;

[0041] [Fig.8] [Fig.8] is a schematic perspective view of the bearing face of one of the flanges visible in [Fig.7];

[0042] [Fig.9] [Fig.9] is a schematic cross-sectional view of a centripetal scoop section of the input shaft of the reducer, as well as the oil jets;

[0043] [Fig. 10] [Fig. 10] is a partial schematic view in axial section of a reducer according to a third embodiment of the invention;

[0044] [Fig. 11] [Fig. 11] is a schematic perspective view of a wheel of an aircraft landing gear and a device for driving this wheel. Detailed description of the invention

[0045] [Fig.l] shows a turbomachine 1 which comprises, in a conventional manner, a fan S, a low-pressure compressor 1a, a high-pressure compressor 1b, an annular combustion chamber 1c, a high-pressure turbine 1d, a low-pressure turbine 1c and an exhaust nozzle 1h. The rotors of the high-pressure compressor 1b and of the high-pressure turbine 1d are connected by a high-pressure shaft 2 and form with it a high-pressure (HP) body. The rotors of the low-pressure compressor 1a and of the low-pressure turbine 1c are connected by a low-pressure shaft 3 and form with it a low-pressure (LP) body.

[0046] The blower S is driven by a fan shaft 4 which is connected to the LP shaft 3 by means of a reducer 6. This reducer 6 is generally of the planetary or epicycloidal type.

[0047] Although the following description relates to a planetary or epicycloidal type reducer, it also applies to a mechanical differential in which its three essential components, namely the planet carrier, the crown and the sun gear, are mobile in rotation, the rotation speed of one of these components depending in particular on the difference in speeds of the other two components.

[0048] The reducer 6 is positioned in the front part of the turbomachine. A fixed structure comprising schematically, here, an upstream part 5a and a downstream part 5b which compose the motor casing or stator 5 is arranged so as to form an enclosure E surrounding the reducer 6. This enclosure E is here closed upstream by seals at the level of a bearing allowing the fan shaft 4 to pass through, and downstream by seals at the level of the passage of the LP shaft 3.

[0049] [Fig.2] shows a part of a reducer 6 which can take the form of different architectures depending on whether certain parts are fixed or rotating. At the input, the reducer 6 is connected to the LP shaft 3, for example via splines 7a. Thus, the LP shaft 3 drives a planetary pinion called the sun gear 7. Conventionally, the sun gear 7, whose axis of rotation coincides with the axis X of the turbomachine, drives a series of pinions called satellites 8, which are equally distributed over the same diameter around the axis of rotation X. This diameter is equal to twice the operating center distance between the sun gear 7 and satellites 8. The number of satellites 8 is generally defined between three and seven for this type of application.

[0050] All of the satellites 8 are held by a frame called a planet carrier 10. Each satellite 8 rotates around its own Y axis, and meshes with the crown 9.

[0051] At the output of reducer 6, we have: • in an epicyclic configuration, the set of satellites 8 drives the planet carrier 10 in rotation around the axis X of the turbomachine. The crown 9 is fixed to the engine casing or stator 5 via a crown carrier 12 and the planet carrier 10 is fixed to the fan shaft 4. • in a planetary configuration, all of the planet gears 8 are held by a planet gear carrier 10 which is fixed to the engine casing or stator 5. Each planet gear drives the crown gear which is attached to the fan shaft 4 via a crown gear carrier 12.

[0052] Each satellite 8 is mounted to rotate freely using a bearing 11, for example of the rolling bearing or hydrostatic bearing type. Each bearing 11 is mounted on one of the axes 10b of the planet carrier 10 and all the axes are positioned relative to each other using one or more structural frames 10a of the planet carrier 10. There is a number of axes and bearings equal to the number of satellites. For reasons of operation, assembly, manufacturing, control, repair or replacement, the axes 10b and the frame 10a can be separated into several parts.

[0053] For the same reasons cited above, the teeth of a reducer can be separated into several helices.

[0054] The teeth of the sun gear 7, the satellites 8 and the crown 9 are for example herringbone, that is to say that they each comprise helices each formed of grooves, the grooves of one of the helices being inclined relative to the grooves of the other propeller.

[0055] In our example, we detail the operation of a herringbone gear reducer with a crown separated into two half-crowns.

[0056] A front half-crown 9a comprises a rim 9aa and a fixing half-flange 9ab. On the rim 9aa is the front helix of the herringbone toothing of the crown 9. This front helix meshes with that of the satellite 8 which meshes with that of the sun 7.

[0057] A rear half-crown 9b comprises a rim 9ba and a fixing half-flange 9bb. On the rim 9ba is the rear helix of the herringbone toothing of the crown 9. This rear helix meshes with that of the satellite 8 which meshes with that of the sun 7.

[0058] The half-fixing flange 9ab of the front crown 9a and the half-fixing flange 9bb of the rear crown 9b form the fixing flange 9c of the crown. The crown 9 is fixed to the crown carrier 12 by assembling the fixing flange 9c of the crown and the fixing flange 12a of the crown carrier using a bolted assembly for example. Furthermore, the crown carrier 12 can be shrunk onto one of the half-crowns 9a, 9b.

[0059] The arrows in [Fig.2] describe the routing of the oil in the reducer 6. The oil arrives in the reducer 6 from the stator part 5 in the distributor 13. The distributor 13 is separated into two parts, generally each repeated by the same number of satellites. The injectors 13a have the function of lubricating the teeth, and the arms 13b have the function of lubricating the bearings 11. The oil is brought to the injector 13a to exit through the end 13c in order to lubricate the teeth. The oil is also brought to each arm 13b and circulates via the supply mouth 13d of the bearing 11. The oil then circulates through the axis 10b in one or more buffer zones 10c to then exit through orifices 10d in order to lubricate the bearings 11 of the satellites.

[0060] [Fig. 3] illustrates another case in which the reducer 6 is equipped with an impeller 14 for distributing oil in the reducer 6, this impeller 14 being supplied by oil jets 15. The impeller 14 has an annular mouth 14a which opens radially inwards and inside which the jets 15 spray oil 16.

[0061] [Fig. 4] shows a nozzle 15 of this type as well as an input shaft 3 of the reducer 6. This shaft 3 is tubular and comprises a flexible or supple, elastically deformable section 18, which is formed by a bellows in the example shown. The bellows shape results in an increase in the external diameter of the shaft 3 which can hinder the installation and positioning of the nozzles 15. In the same way, the presence of the nozzles 15 in this zone can limit the external diameter of the shaft 3 and so the deformation capacities of the input shaft 3.

[0062] The present invention proposes a solution to this problem, several embodiments of which are illustrated in Figures 5 and following.

[0063] The invention relates to a mechanical speed reducer 6 equipped with an input shaft 3.

[0064] The foregoing description may be used to illustrate features of the invention, particularly with respect to the reducer 6.

[0065] The reducer 6 comprises:

[0066] - a solar 7 mobile in rotation around an axis X and comprising at least one external dentition,

[0067] - a crown 9 extending around the axis X and comprising at least one toothing internal, and

[0068] - satellites 8 distributed around the X axis and meshed respectively with the teeth of the sun 7 and the crown 9, the satellites 8 being mobile in rotation around axes Y parallel to the axis X, and

[0069] - a system 20 for lubricating at least part of the reducer 6.

[0070] The input shaft 3 is tubular and has an end 3a engaged axially in solar 7 and coupled to the latter for its rotation drive.

[0071] The input shaft 3 comprises a first elastically deformable section 18 which comprises two annular walls 18a, 18b which face each other axially.

[0072] These annular walls 18a, 18b have their external peripheries which are connected together and their internal peripheries which are connected to the rest of the shaft 3.

[0073] According to the invention, the annular walls 18a, 18b of the first section 18 define between them at least one oil circulation passage 22 which is in fluid communication with orifices 24 formed in the first section 18 and configured to spray oil 16 in operation for the purpose of supplying the lubrication system 20.

[0074] In the embodiment of Figures 5 and 6, the first section 18 forms a portion of bellows of the shaft 3 or is part of a bellows of the shaft 3.

[0075] The first section 18 is formed from a single piece and the annular walls 18a, 18b are axially spaced from one another to define between them the oil circulation passage 22, which is annular.

[0076] The annular walls 18a, 18b are connected at their external peripheries by an annular connecting wall 18c which comprises the orifices 24. The first section 18 may have a general U-shape in cross-section as in the example illustrated.

[0077] The annular walls 18a, 18b may be parallel to each other, as in the example shown. Alternatively, they could be inclined relative to each other, in particular to optimize the flow of oil between them.

[0078] The walls 18, 18b may have identical external diameters, as in the example shown. The connecting wall 18c thus has a generally cylindrical shape.

[0079] Alternatively, the walls 18, 18b could have different diameters and the connecting wall 18c would then have a generally truncated cone shape.

[0080] The first section 18 is located radially inside an impeller 14 of the lubrication system 20. The orifices 24 are configured to spray oil 16 into the annular mouth 14a of the impeller 14.

[0081] The shaft 3 further comprises a second section 26, at a distance from the first section 18, this second section 26 forming a centripetal scoop 28 and comprising radial through-holes 30 for the passage of oil 16.

[0082] Oil jets 32 are located radially outside the shaft 3 and are configured to spray oil 16 radially inside the shaft 3 through the ports 30 of the scoop 28 (Figures 5 and 6).

[0083] The oil jets 32 may comprise oil projection axes which are inclined relative to radial axes with respect to the X axis ([Fig.9]).

[0084] In operation, as schematically illustrated in [Fig.5], the nozzles 32 spray oil 16 towards the scoop 28 which has the function of collecting the oil and making it penetrate radially inside the shaft 3 through its ports 30. The oil then circulates axially from the section 26 towards the section 18 of the shaft 3, due to centrifugal forces, flowing along its internal wall. The oil reaches the passage 22 and is forced to flow to the orifices 24 due to the centrifugal forces. The oil is then sprayed radially outside the shaft 3 and inside the impeller 14.

[0085] The flow of oil in the shaft 3, from its section 26 to its section 18, can be facilitated by a slight taper of the portion of the shaft 3 between its sections 26, 18. Alternatively, a radially internal annular rib 44 could be located inside the shaft 3 to force the oil to flow towards the section 18. In the example shown, this rib 44 is located just downstream of the scoop 28, the section 18 being located upstream of the section 26.

[0086] In the embodiment of figures 7 and 8, the first section 18 is formed by two flanges 34a, 34b respectively forming the two annular walls 18a, 18b.

[0087] These two flanges 34a, 34b are applied axially to one another and fixed to one another by screws 36 which axially pass through holes 38 of the flanges 34a, 34b.

[0088] Lunules 40 are formed in at least one of the annular faces opposite the flanges 34a, 34b to form the oil circulation passages 22 which form at their radially external ends the aforementioned oil projection orifices 24.

[0089] In the example shown, there are as many lunules 40 and therefore passages 22 as there are holes 38, each lunule 40 being arranged between two holes 38, and each hole 38 being arranged between two lunules 40.

[0090] The shaft 3 further comprises a second section 26 equipped with a centripetal scoop 28 and associated with oil jets 32, as mentioned above.

[0091] In operation, as schematically illustrated in [Fig.7], the nozzles 32 spray oil 16 towards the scoop 28 which has the function of collecting the oil and making it penetrate radially inside the shaft 3 through its ports 30. The oil then circulates axially from the section 26 towards the section 18 of the shaft 3, due to centrifugal forces, flowing along its internal wall. The oil reaches the passages 22 and is forced to flow to the orifices 24 due to the centrifugal forces. The oil is then sprayed radially outside the shaft 3 and inside the impeller 14.

[0092] The flow of oil in the shaft 3, from its section 26 to its section 18, can be facilitated by a slight taper of the portion of the shaft 3 between its sections 26, 18. As a variant, a radially internal annular rib 44 could be located inside the shaft 3 to force the oil to flow towards the section 18. In the example shown, this rib 44 is located downstream of the scoop 28, the section 18 being located upstream of the section 26.

[0093] In the embodiment variant of [Fig. 10], the first section 18 is similar to that described with reference to FIGS. 5 and 6, and is located radially inside the solar 7.

[0094] The shaft 3 further comprises a second section 26 equipped with a centripetal scoop 28 and associated with oil jets 32, as mentioned above.

[0095] The orifices 24 are configured to spray oil 16 inside the solar 7, and preferably between the grooves 7a of the solar 7 and a level ring 42 mounted inside the solar 7.

[0096] In operation, as schematically illustrated in [Fig. 10], the nozzles 32 spray oil 16 towards the scoop 28 which has the function of collecting the oil and making it penetrate radially inside the shaft 3 through its ports 30. The oil then circulates axially from the section 26 towards the section 18 of the shaft 3, due to centrifugal forces, flowing along its internal wall. The oil reaches the passage 22 and is forced to flow to the orifices 24 due to the centrifugal forces. The oil is then sprayed radially inside the solar.

[0097] It is pressed radially against an internal surface of the sun 7 and flows axially towards the toothing 7a to the extent that it is blocked on the opposite side by the level ring 42. Alternatively, a radially internal annular rib 44 could be located inside the shaft 3 to force the oil to flow towards the section 18. In the example shown, this rib 44 is located just downstream of the scoop 28, the section 18 being located upstream of the section 26.

[0098] Although the invention has been described in the context of a reducer 6 of an aircraft turbomachine, it applies to other environments. It can for example be applied to a reducer for a device for driving at least one wheel of an aircraft landing gear, such as that illustrated in [Fig. 11].

[0099] [Fig. 11] shows a device 120 for driving at least one wheel 122 of an aircraft landing gear 124.

[0100] The wheel 122 comprises a rim 126 which has an axis of rotation X. Conventionally, this rim 126 has a generally tubular or disc shape and carries a tire 128 at its periphery.

[0101] The device 120 comprises an electric motor 130 and a mechanical transmission system 132 between a shaft of the motor 130 and the rim 116 of the wheel 122.

[0102] In the example shown, the motor 130 and the system 132 each have a generally annular shape and are centered on the X axis. They are arranged next to each other and the system 132 is installed between the motor 130 and the rim 126. A part of the system 132, or even also a part of the motor 130, could be housed in the rim 126 to reduce the size of the device 120. The motor 130 and the system 132 can be protected by an external cylindrical cover 136 projecting on one side of the rim 126 or the tire 128.

[0103] The mechanical transmission system 132 comprises a mechanical speed reducer 6 as described above.

Claims

Claims

1. Mechanical reducer (6) comprising: - an input shaft (3) - a sun gear (7) rotatable about an axis X and comprising at least one external toothing (7a), - a crown (9) extending about the axis X and comprising at least one internal toothing, - satellites (8) distributed about the axis X and meshed respectively with the teeth of the sun gear (7) and the crown (9), the satellites (8) being rotatable about axes Y parallel to the axis X, and - a system (20) for lubricating at least a part of the reducer (6), the input shaft (3) being tubular and comprising one end (3a) axially engaged in the sun gear (7) and coupled to the latter for its rotational drive, the input shaft (3) comprising a flexibility section (18) which comprises two annular walls (18a, 18b) which face axially, these annular walls (18a,18b) having their radially outer ends which are connected together and their radially inner ends which are connected to the rest of the shaft (3), characterized in that the annular walls (18a, 18b) of the flexibility section (18) define axially between them at least one passage (22) for circulation of oil which is in fluid communication with orifices (24) formed in the flexibility section (18) and configured to project oil in operation for the purpose of supplying said lubrication system (20).,

2. Reducer according to claim 1, in which the first section (18) is formed in a single piece and the annular walls (18a, 18b) are axially spaced from each other to define between them said oil circulation passage (22), which is annular, these annular walls (18a, 18b) being connected at their external peripheries by an annular connecting wall (18c) which comprises said orifices (24).

3. Reducer according to claim 1 or 2, in which the first section (18) forms a bellows portion of the shaft (3) or is part of a bellows of the shaft (3).

4. Reducer according to claim 1, in which the first section (18) is formed by two flanges (34a, 34b) respectively forming the two annular walls (18a, 18b), these two flanges (34a, 34b) being fixed to each other by screws (36) which axially pass through holes (38) of the flanges (34a, 34b), lunules (40) being formed in at least one of the annular faces opposite the flanges (34a, 34b) to form said oil circulation passages (22) which form at their radially external ends said orifices (24).

5. Reducer according to one of the preceding claims, in which the first section (18) is located radially inside the solar (7), the orifices (24) being configured to spray lubricating oil from the solar (7).

6. Reducer according to one of the preceding claims, in which the first section (18) is located radially inside an impeller (14) of said lubrication system (20), the orifices (24) being configured to project oil into an annular mouth (14a) of the impeller (14) which is oriented radially inwards with respect to the axis X.

7. Reducer according to one of the preceding claims, in which the shaft (3) comprises a second section (26), at a distance from the first section (18), this second section (26) forming a centripetal scoop (28) and comprising radial through-holes (30) for the passage of oil.

8. Reducer according to the preceding claim, wherein it further comprises at least one oil jet (32) located radially outside the shaft (3) and configured to spray oil radially inside the shaft (3) through said ports (30).

9. Reducer according to the preceding claim, in which each oil nozzle (32) has an oil projection axis inclined relative to a radial direction with respect to the X axis.

10. Aircraft turbomachine, comprising a mechanical speed reducer (28) according to one of the preceding claims.

11. Device (120) for driving at least one wheel (122) of an aircraft landing gear (124), this device (120) comprising a mechanical speed reducer (6) according to one of the preceding claims.

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