MECHANICAL SPEED REDUCER WITH OIL SPARKLING

Abstract

Mechanical speed reducer (6), this reducer comprising a sun gear (7), at least one ring gear (9), satellite gears (8), and a satellite carrier (10), characterized in that the reducer (6) is capable of containing and storing a quantity of oil such that at least a portion of the gears of the reducer (6) bubble in the oil during operation, each of the satellite gears (8) is configured to form an oil scoop during operation, the cavity (40) of each of the satellite gears (8) opening axially at the axial extremities of the satellite gear (8) and comprising two axial end portions (40a) of smaller diameters (D1) and a central portion (40b) of larger diameter (D2) situated between the two axial end portions (40a). Figure for the abbreviation: Figure 6

Description

Title of the invention: MECHANICAL SPEED REDUCER WITH OIL SPLASH Technical field of the invention

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

[0002] The state of the art includes in particular documents FR-A1-2 987 416, FR-Al-2 853 382, ​​FR-A1-3 041 054, FR-A1-3 073 915, FR-A1-3 084 428.

[0003] The role of a mechanical reducer is to modify the speed ratio and the torque between the input axis and the output axis of a mechanism.

[0004] New generations of dual-flow turbomachines, particularly those with a high bypass ratio, include a mechanical reducer to drive the shaft of a fan (also called a "fan"). Usually, the reducer aims to transform the so-called fast rotation speed of the shaft of a power turbine into a slower rotation speed for the shaft driving the fan.

[0005] 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 and are 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 the state of the art of double-flow turbomachines, the reducers are of the planetary or epicyclic type. In other similar applications, there are so-called differential or "compound" or Wolfrom architectures (with two crowns instead of one).

[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 of 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 field. There are several types of contact meshing such as straight or herringbone teeth.

[0011] Lubricating a speed reducer is important to ensure its operation. There are several technologies for lubricating a reducer.

[0012] A first technology consists of spraying oil into the reducer, in particular onto the gears, by means of nozzles which are supplied with oil by an oil container located outside the reducer.

[0013] Another technology consists of conveying oil into the reducer by means of pipes which are integrated into the reducer and which are also supplied with oil by a container located outside the reducer. This technology can be combined with the first within the same reducer.

[0014] Another technology consists of the reducer containing a sufficient quantity of oil necessary for its operation, that is to say that the oil intended to ensure its lubrication is already within the reducer which is thus not supplied with oil by an external container. In this technology, the reducer is of the oil bath or splash type, that is to say that the reducer contains an oil bath in which at least some of the gears are immersed. The rotation of the rotating elements allows the gears to drive the oil and lubricate the entire reducer. The oil which accumulates by gravity in the lower part of the reducer is then brought to the upper part to be distributed within the reducer.

[0015] However, in practice, the entrainment of oil in the reducer and therefore the lubrication of the reducer depends on the rotational speed of its rotating elements. When the reducer is at low speed, the rotational speed of its rotating elements may prove insufficient to entrain the oil and properly lubricate the reducer.

[0016] The present invention provides a solution to this problem, which is simple, effective and economical. Summary of the invention

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

[0018] - a mobile solar rotating around an axis X, called the central axis, and comprising at least one external dentition,

[0019] - at least one crown extending around the X axis and comprising at least one internal teeth,

[0020] - satellites distributed circumferentially around the X axis and meshed respec tively with the teeth of the sun gear and the crown(s), the satellites being mobile in rotation around Y axes, called bearing axes, parallel to the X axis and each comprising an internal cavity extending along the Y axis, and

[0021] - a mobile satellite carrier rotating around the X axis and carrying the satellites,

[0022] characterized in that the reducer is capable of containing and storing a quantity of oil so that at least a portion of the gears of the reducer splash in the oil during operation, and in that the internal cavity of each of the satellites is configured to form an oil scoop during operation, the cavity of each of the satellites opening axially at at least one of the axial ends of the satellite and comprising two axial end portions of smaller diameters and a middle portion of larger diameter located between the two axial end portions.

[0023] The particularity of the invention lies in the fact that the satellites are configured to have a scoop function in operation. The satellites are hollow due to the presence of the cavity and this cavity is shaped to be able to receive in its middle part a certain quantity of oil. When the satellites rotate around their axes and the axis of the reducer, this oil is centrifuged and flows through at least one of the ends of the satellites, and more particularly the end parts of their cavities.

[0024] Both ends of the cavity of each satellite can be open and therefore open outwards. Alternatively, only one of these ends can be open, the other end of the cavity being closed. It is understood that the internal diameter of a closed end of the cavity is equal to zero.

[0025] The invention is compatible with a single- or multi-stage reducer as mentioned above. It is also compatible with a reducer whose planet carrier is rotatable, such as epicyclic, differential or Wolfrom type reducers. It is also compatible with teeth of any type (straight, helical, chevron, etc.). The invention is also compatible with a planet carrier of the monobloc type or of the cage and cage carrier type. These different types of reducer are well known to those skilled in the art. The solution proposed below is compatible with any type of satellite bearing, whether it is composed of rolling elements, a hydrodynamic bearing, etc.

[0026] The reducer may comprise one or two crowns. In the case of a Wolfrom type reducer, it comprises two crowns each comprising a toothing. In the case of a double-stage reducer, the two toothings may be carried by a single crown or by separate crowns.

[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: - the middle portion extends over more than 50% of a length or axial dimension of the satellite measured along the bearing axis Y; - the middle part extends over more than 80% of a length or axial dimension of at least one external tooth of the satellite measured along the bearing axis Y ; - the middle part has a constant internal diameter or is stepped and comprises at least two distinct internal diameters; - the axial end portions have identical internal diameters, and / or each extend over at least 10% of a length or axial dimension of the satellite measured along the bearing axis Y;

[0028] — the axial end portions have different internal diameters;

[0029] — one of the axial end portions has a zero diameter because the cavity is closed at the level of this end part, - at least one protruding deflector is located in the middle part of the cavity of each of the satellites; - the projecting deflector is chosen from a rib, a fin, a series of successive ribs or fins, an annular row of ribs or fins; - each of the ribs or fins has a length which represents at least 40% of a length or an axial dimension of the middle part of the cavity measured along the bearing axis Y; - guide bearings are mounted between the axial ends of the satellites and the planet carrier, oil passage holes being formed in these axial ends and opening at the axial end parts of the cavities of the satellites; - oil passage holes are formed in each of the satellites and extend, preferably inclined relative to an axis radial to the bearing axis Y of the satellite, from the middle part of the cavity to at least one external toothing of the satellite or to an annular cavity or axial lubrication bores of a guide bearing of the satellite; - at least two level rings are mounted inside the cavity of each of the satellites so as to define an oil level inside the cavity of each of the satellites; - axial grooves are formed in the middle part of the cavity of each of the satellites, and are for example regularly distributed around the axis of each satellite.

[0030] The present invention also relates to an aircraft turbomachine, comprising a mechanical speed reducer as described above.

[0031] 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

[0032] 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:

[0033] [Fig-1] [Fig.l] is a half schematic view in axial section of a turbomachine aircraft,

[0034] [Fig.2] [Fig.2] is a half schematic view in axial section of a mechanical speed reducer,

[0035] [Fig.3] [Fig.3] is a schematic perspective view of a wheel of an aircraft landing gear and a device for driving this wheel,

[0036] [Fig.4] [Fig.4] is a schematic axial sectional view of a mechanical splash speed reducer,

[0037] [Fig.5] [Fig.5] is a schematic cross-sectional view of a mechanical splash speed reducer,

[0038] [Fig.6] [Fig.6] is a schematic axial sectional view of a satellite for a reducer according to the invention;

[0039] [Fig.7] [Fig.7] is a schematic axial sectional view of a satellite for a reducer according to the invention;

[0040] [Fig.8] [Fig.8] is a schematic axial sectional view of a satellite for a reducer according to the invention;

[0041] [Fig.9] [Fig.9] is a schematic axial sectional view of a satellite for a reducer according to the invention;

[0042] [Fig. 10] [Fig. 10] is a schematic axial sectional view of a satellite for a reducer according to the invention;

[0043] [Fig. 11] [Fig. 11] is a schematic axial sectional view of a satellite for a reducer according to the invention;

[0044] [Fig.l2a-12b] Figures 12a and 12b are schematic views, respectively in cross-section and axial section of a satellite for a reducer according to the invention;

[0045] [Fig. 13] [Fig. 13] is a schematic cross-sectional view of the satellite of figures 12a and 12b which is mounted in a reducer and which is bathed in an oil bath of this reducer;

[0046] [Fig. 14] [Fig. 14] is a schematic axial sectional view of a satellite for a reducer according to the invention;

[0047] [Fig. 15] [Fig. 15] is a schematic axial sectional view of a satellite for a reducer according to the invention; Detailed description of the invention

[0048] [Fig. 1] describes 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.

[0049] The blower S is driven by a blower 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.

[0050] Although the following description concerns 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.

[0051] The reducer 6 is positioned in the front part (or upstream, with respect to the general direction of flow of the gases in the turbomachine in operation) 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.

[0052] [Fig.2] shows a part of a reducer 6 which can take the form of dif 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 X axis 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 the satellites 8. The number of satellites 8 is generally defined between three and seven for this type of application.

[0053] The set of satellites 8 is held by a chassis called a planet carrier 10. Each satellite 8 rotates around its own Y axis, and meshes with the crown 9.

[0054] 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 carrier 10 which is fixed to the engine casing or stator 5. Each planet gear drives the crown which is attached to the fan shaft 4 via a crown carrier 12.

[0055] 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.

[0056] For the same reasons cited above, the teeth of a reducer can be separated into several helices.

[0057] In our example we detail the operation of a herringbone gear reducer with a crown separated into two half-crowns.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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 by different means which will not be specified in this view because they are specific to one or more types of architecture. 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 port 13d of the bearing 11. The oil then circulates through the shaft 10b in one or more buffer zones 10c and then exits through ports 10d in order to lubricate the bearings 11 of the satellites.

[0062] [Fig. 3] shows a device 20 for driving at least one wheel 22 of an aircraft landing gear 24.

[0063] The wheel 22 comprises a rim 26 which has an axis of rotation X. Conventionally, this rim 26 has a generally tubular or disc shape and carries a tire 28 at its periphery.

[0064] The device 20 comprises an electric motor 30 and a mechanical transmission system 32 between a shaft of the motor 30 and the rim 116 of the wheel 22.

[0065] In the example shown, the motor 30 and the system 32 each have a generally annular shape and are centered on the axis X. They are arranged next to each other and the system 32 is installed between the motor 30 and the rim 26. A part of the system 32, or even also a part of the motor 30, could be housed in the rim 26 to reduce the size of the device 20. The motor 30 and the system 32 can be protected by an external cylindrical cover 36 projecting on one side of the rim 26 or the tire 28.

[0066] The mechanical transmission system 32 comprises a mechanical speed reducer 6 as described above.

[0067] The [Fig.2] described in the above illustrates the lubrication technology of a reducer 6 by projection and / or circulation of oil, this oil coming from an oil container located outside the reducer 6.

[0068] Figures 4 and 5 show another lubrication technology for a reducer 6 of the oil bath or splash type. In these figures, the elements already described in the above with reference to [Fig.2] are designated by the same references.

[0069] This type of reducer 6 is capable of containing and storing a quantity of oil so that at least part of the gears of the reducer splash in the oil during operation.

[0070] In general, the rotation of the rotating elements, such as the satellites, allows the gears to drive the oil and lubricate the entire reducer 6. The oil which accumulates by gravity in the lower part of the reducer 6 is then brought to the upper part to be distributed within the reducer 6.

[0071] The present invention proposes an improvement to this technology which makes it possible to improve and make more reliable the lubrication of all the gears of the reducer 6.

[0072] According to the invention, each of the satellites 8 has a cavity 40 which is configured to form an oil scoop in operation.

[0073] The cavity 40 of each of the satellites 8 opens axially at the axial ends of the satellite 8 and comprises two axial end parts 40a of smaller diameters DI and a middle part 40b of larger diameter D2 located between the two axial end parts 40a.

[0074] Figures 6 and following illustrate several variant embodiments of a satellite 8 for a reducer 6 according to the invention.

[0075] The description of the satellite of a reducer applies to all the satellites of the reducer insofar as the satellites are preferably identical. Although the following description focuses on the satellites, these satellites are intended to be mounted in a reducer as described in the foregoing. Therefore, the foregoing description can be used to also describe the invention with regard to the reducer as a whole.

[0076] Generally, the middle part 40a of the cavity 40 of each satellite 8 preferably extends over more than 50% of a length L1 or axial dimension of the satellite 8 measured along the Y axis.

[0077] The middle part 40b can extend over more than 80% of a length L2 or axial dimension of at least one external toothing of the satellite 8 measured along the Y axis.

[0078] The axial end portions 40a preferably have identical internal diameters DI, and for example constant over their entire length. Alternatively, these diameters DI may be different.

[0079] The axial end portions 40a may each extend over at least 10% of the length L1 or axial dimension of the satellite 8 measured along the Y axis.

[0080] In [Fig.6], the middle part 40b has a constant internal diameter D2 and is connected to the end parts 40a respectively by truncated conical portions 40c.

[0081] When the satellites pass through the oil bath, the hollow cavities 40 can recover a certain quantity of oil. To maximize this quantity of oil, it is possible to increase the volume of the cavities 40 and for example the diameter of their middle parts 40b. The oil contained in the cavity 40 is distributed by “overflow” onto the bearings when the satellites 8 are outside the oil bath.

[0082] The satellite 8 of [Fig.7] comprises the characteristics of the satellite 8 of [Fig.6] and additionally comprises at least one projecting deflector 50 which is located in the middle part 40b of the cavity 40.

[0083] Generally, a deflector 50 of this type allows the oil to be driven with the rotation of the satellite. Each deflector tends to push the oil axially and / or to drive or stir the oil, in order to force its movement and thus avoid the formation of a static oil ring in the satellite.

[0084] The projecting deflector 50 may be chosen from a rib, a fin, a series of successive ribs or fins, an annular row of ribs or fins. In the example shown, the deflectors are ribs or fins of elongated rectilinear shape. Alternatively, the deflectors could have a curved shape for example.

[0085] The or each deflector 50 is preferably parallel to the Y axis of the satellite 8.

[0086] The or each deflector 50 may have a length that represents at least 40% of a length L3 or axial dimension of the middle part 40b of the cavity 40 measured along the axis Y, and which represents at least 90% of this length L3. In the example shown, the or each deflector 50 extends over the entire length L of the middle part 40b including at the level of the frustoconical portions 40c.

[0087] The or each deflector 50, and in particular the or each rib or fin, comprises a free edge 50a which extends along the axis Y, and which is located on the same circumference centered on the axis Y. This circumference has a diameter D3 corresponding to the internal diameter DI of the end portions 40a of the cavity 40. In other words, the edges 50a of the ribs or fins extend in the extension of the internal cylindrical surfaces of the end portions 40a. Alternatively, D3 could be different from DI.

[0088] The satellite 8 of [Fig.8] differs from that of [Fig.7] in that the or each deflector 50 is inclined relative to the Y axis, for example by an angle of between 5 and 45°, and preferably between 10 and 30°.

[0089] The or each deflector 50 has a length which represents at least 90% of a length L1 or axial dimension of the middle part 40b of the cavity 40 measured along the Y axis.

[0090] The satellite of [Fig.9] differs from that of [Fig.7] in that the or each deflector 50 is replaced by a pair of deflectors 50.

[0091] Each satellite 8 thus comprises at least one pair of deflectors, such as ribs or fins, the or each pair comprising two deflectors 50 extending one after the other, along the Y axis. The first deflector 50a of the pair can be inclined at an angle of between +5 and +45°, and preferably between +10 and +30° with respect to the Y axis, and the second deflector 50b of the pair can be inclined at an angle of between -5 and -45°, and preferably between -10 and -30° with respect to the Y axis.

[0092] The or each deflector 50 has a length L4 which represents at least 40% of an axial length or dimension of the middle portion 40b of the cavity 40 measured along the Y axis.

[0093] Satellite 8 of [Fig. 10] similar to that of [Fig.6].

[0094] Guide bearings 60 are mounted between the axial ends of the satellites 8 and the satellite carrier 10.

[0095] Oil passage orifices 70 are preferably formed in these axial ends and open at the end portions 40a of the cavity 40 of the satellite. 8.

[0096] The orifices 70 of [Fig. 10] are preferably oriented radially relative to the Y axis.

[0097] It is therefore understood that a portion of the oil which flows during operation from the middle portion 40b of the cavity 40 to the end portions 40a can penetrate into the orifices 70 and circulate to the bearings 60 for the purpose of lubricating them.

[0098] The satellite of [Fig.l 1] differs from that of [Fig.6] in particular in that the middle part 40b of its cavity 40 is stepped and comprises at least two distinct internal diameters.

[0099] The satellite 8 is guided in rotation by bearings 60 as in the previous embodiment, and the satellite 8 of [Fig. 11] comprises an annular groove which extends around the axis Y or holes 80 which extend parallel to the axis Y, and open axially towards one of these bearings 60.

[0100] Oil passage orifices 70 are preferably formed in the middle part 40b of the cavity 40 and open at the lubrication groove 80 of the bearing 60.

[0101] The orifices of [Fig.9] are preferably inclined relative to the Y axis.

[0102] It is therefore understood that a part of the oil which is contained in the middle part 40b of the cavity 40 can penetrate into the orifices 70 and circulate into the groove 80 and the bearing 60 for lubrication.

[0103] The satellite of figures 12a, 12b and 13 differs from that of [Fig.6] in particular in that oil passage orifices 70 are formed in the middle part 40b and open at the level of an external toothing of the satellite 8, or between two annular rows of this toothing.

[0104] In a plane perpendicular to the Y axis, these orifices 70 are inclined relative to rays centered on this Y axis as illustrated in figures 12a and 13. The orientation of this inclination is determined in operation of the direction of rotation of the satellites 8 around the Y axes, so as to ensure the scooping function by the satellite ([Fig. 13]).

[0105] It is therefore understood that a portion of the oil which is located in the middle part 40b of the cavity 40 in operation flows to the teeth of the satellite 8 for the purpose of its lubrication.

[0106] Alternatively, the operation could be reversed, the orifices 70 would draw oil from the overall bath of the reducer in order to supply the cavity 40.

[0107] Figures 12a and 12b further show that axial grooves 75 are formed in the middle portion 40b of the cavity 40 in order to avoid the formation of a static oil ring in the satellite cavity. The grooves 75 are preferably regularly distributed around the Y axis.

[0108] The satellite of [Fig. 14] differs from that of [Fig. 10] in that it further comprises two level 90 rings which are mounted inside the cavity 40.

[0109] The level rings 90 make it possible to increase the oil storage volume in the cavity 40 of the satellite 8, and / or to force the oil contained in the cavity to flow through the oil passage orifices formed in the satellite and opening into the cavity 40.

[0110] The level rings 90 are located respectively in the end parts 40a of the cavity 40 of the satellite 8, and more particularly they are each located between the outlets of the orifices 70 on the one hand, and the free end closest to the satellite 8 on the other hand.

[0111] These level rings 90 make it possible to contain an additional quantity of oil in each satellite 8 and to better control the flow of oil through these rings 90 during operation.

[0112] The satellite of [Fig. 15] differs from that of [Fig. 14] in that it further comprises two other level rings 100 which are mounted inside the cavity 40, in its middle part 40b.

[0113] The two level rings 100 make it possible to define between them an annular oil passage 110 which communicates with oil circulation orifices 120 opening onto the toothing between two propellers of the toothing of the satellite 8.

[0114] The orifices 70 described in the various embodiments may have any cross-sectional shape and may have a constant or changing cross-section along their length. Flow restrictors may also be mounted in these orifices 70. This may, for example, ensure that the oil reserve in the satellite does not run out before the satellite next passes through the oil bath.

[0115] In yet another variant not shown, the cavity 40 of each of the satellites 8 could be closed at one end and therefore open outwards at only one of its axial ends or its axial end parts.

[0116] The invention makes it possible to collect a reserve of oil inside each satellite, during their passage in the oil bath at the low point of the reducer in order to redistribute it during the rest of the rotation. This therefore makes it possible to guarantee a sufficient supply of oil throughout the rotation even at low speed.

Claims

Claims

1. Mechanical speed reducer (6), this reducer comprising: - a sun gear (7) rotatable about an axis X and comprising at least one external toothing, - at least one crown (9) extending about the axis X and comprising at least one internal toothing, - satellites (8) distributed circumferentially about the axis X and meshed respectively with the teeth of the sun gear (7) and the crown(s) (9), the satellites (8) being rotatable about bearing axes Y parallel to the axis X and each comprising an internal cavity (40) extending along the bearing axis Y, and - a planet carrier (10) rotatable about the axis X and carrying the satellites (8), characterized in that the reducer (6) is capable of containing and storing a quantity of oil so that at least part of the gears of the reducer (6) splash in the oil while operating,and in that the internal cavity (40) of each of the satellites (8) is configured to form an oil scoop in operation, the cavity (40) of each of the satellites (8) opening axially at at least one of the axial ends of the satellite (8) and comprising two axial end parts (40a) of smaller diameters (D1) and a middle part (40b) of larger diameter (D2) located between the two axial end parts (40a).,

2. Reducer (6) according to claim 1, wherein the middle portion (40b) extends over more than 50% of a length (Ll) or an axial dimension of the satellite (8) measured along the bearing axis Y.

3. Reducer (6) according to claim 1 or 2, wherein the middle portion (40b) extends over more than 80% of a length (L2) or axial dimension of at least one external toothing of the satellite (8) measured along the bearing axis Y.

4. Reducer (6) according to one of the preceding claims, in which the middle part (40b) has a constant internal diameter (D2) or is stepped and comprises at least two distinct internal diameters.

5. Reducer (6) according to one of the preceding claims, in which the axial end portions (40a) have identical internal diameters (Dl), and / or each extend over at least 10% of a length (Ll) or of an axial dimension of the satellite (8) measured along of the Y bearing axis.

6. Reducer (6) according to one of the preceding claims, in which at least one projecting deflector (50) is located in the middle part (40b) of the cavity (40) of each of the satellites (8).

7. Reducer (6) according to the preceding claim, in which the projecting deflector (40) is chosen from a rib, a fin, a series of successive ribs or fins, an annular row of ribs or fins.

8. Reducer (6) according to the preceding claim, in which each of the ribs or fins has a length (L4) which represents at least 40% of a length (L3) or of an axial dimension of the middle part (40b) of the cavity (40) measured along the bearing axis Y.

9. Reducer (6) according to one of the preceding claims, in which guide bearings (60) are mounted between the axial ends of the satellites (8) and the planet carrier (10), oil passage orifices (70) being formed in these axial ends and opening at the axial end parts (40a) of the cavities (40) of the satellites (8).

10. Reducer (6) according to one of the preceding claims, in which oil passage orifices (70) are formed in each of the satellites (8) and extend, preferably in an inclined manner relative to an axis radial to the bearing axis Y of the satellite (8), from the middle part (40b) of the cavity (40) to at least one external toothing of the satellite (8) or to an annular cavity or axial bores (80) for lubricating a guide bearing (60) of the satellite.

11. Reducer (6) according to one of the preceding claims, in which axial grooves (75) are formed in the middle part (40b) of the cavity (40) of each of the satellites (8).

12. Reducer (6) according to one of the preceding claims, in which at least two level rings (90, 100) are mounted inside the cavity (40) of each of the satellites (8) so as to define an oil level inside the cavity (40) of each of the satellites (8).

13. Aircraft turbomachine, comprising a mechanical speed reducer (6) according to one of the preceding claims.

14. Device (20) for driving at least one wheel (22) of an aircraft landing gear, this device comprising a mechanical speed reducer (6) according to one of claims 1 to 12.

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