MOVING CROWN FOR AN AIRCRAFT MECHANICAL REDUCER

Abstract

A movable ring gear (109, 209a) for a mechanical splash-type gearbox (106, 206), particularly for aircraft, this ring gear (109, 209a) having an annular shape around a longitudinal axis (X) and comprising: - an annular body (130), and - internal teeth (132), characterized in that it further comprises, on the outer periphery of the body (130), an annular row of oil scoops (136), these scoops (136) being distributed around said longitudinal axis (X) and projecting from an external annular surface (134) of the body (130). Figure for the abbreviation: Figures 5a-5b

Description

Title of the invention: MOVING CROWN FOR A MECHANICAL AIRCRAFT REDUCER Technical field of the invention

[0001] The present invention relates to a movable ring for an aircraft mechanical reducer, and in particular for an aircraft turbomachine or for a drive system for a wheel of an aircraft landing gear. Technical background

[0002] The state of the art includes in particular documents FR-A1-3 025 780, FR-B1-3 066 792, FR-B1-3 071 023, FR-3 072 749, FR-A1-3 095 243, FR-B1-3 098 562, FR-B1-3 101 129, US-A-4,864,893 and US-B2-10,807,467.

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

[0004] New generations of turbofan engines, particularly those with a high bypass ratio, include a mechanical gearbox to drive the shaft of a fan. Typically, the purpose of the gearbox is to transform the high rotational speed of the power turbine shaft into a slower rotational speed for the fan-driving shaft.

[0005] A wheel drive system of a landing gear may further include a mechanical reducer, as proposed by the Applicant in document EP-A1-3 882 136.

[0006] Such a reduction gear comprises a central pinion, called the sun gear, a ring gear, and pinions called planet gears, which mesh between the sun gear and the ring gear. The planet gears are held by a frame called a planet carrier. The sun gear, ring gear, and planet carrier are planetary gears because their axes of revolution coincide with the axis of the turbomachine or landing gear wheel. The planet gears each have a different axis of revolution, equally spaced on the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis X.

[0007] Several gearbox architectures exist. In the state of the art, gearboxes are of the planetary or epicyclic type. In other similar applications, there are so-called differential or "compound" architectures.

[0008] - On a planetary gearbox, the planet carrier is fixed and the ring gear constitutes the output shaft of the device which rotates in the opposite direction to the solar.

[0009] - On an epicyclic reducer, the ring gear is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar panel.

[0010] - On a differential reducer, no element is fixed for rotation. The ring rotates in the opposite direction to the solar panel and the satellite carrier.

[0011] Gear reducers can be composed of one or more meshing stages. This meshing is achieved in various ways, such as by contact, friction, or magnetic fields. There are several types of contact meshing, such as with spur, helical, or herringbone teeth.

[0012] Reducers can be composed of one or more meshing stages. This meshing is achieved in various ways such as by contact, by friction or by magnetic fields.

[0013] A satellite may comprise one or two gear stages. In this application, "stage" or "gear" means a series of meshing teeth with a series of complementary teeth. A gear may be internal or external. A single-stage satellite comprises a gear that may be straight, helical, or chevron-shaped, and whose teeth are located on the same diameter. This gear cooperates with both the sun gear and the crown gear.

[0014] A two-stage satellite comprises two sets of teeth or two series of teeth which are located on different diameters. A first set of teeth cooperates with the sun gear and a second set of teeth cooperates with the crown gear.

[0015] There is also a configuration, called Wolfrom, in which the satellites are double-staged and comprise a first set of teeth that cooperate with the sun gear and a ring gear, and a second set of teeth that cooperate with a second ring gear. The reduction gear thus comprises two ring gears, one of which is fixed and the other movable.

[0016] A mechanical reducer must be lubricated to ensure its operation and also to dissipate the heat generated during operation. For this purpose, lubricating oil is used.

[0017] There are two technologies for lubricating a mechanical reducer.

[0018] The first technology consists of lubricating the gearbox with oil jets. The jets are supplied with oil and spray oil onto the gears, i.e. the teeth of the solar cell, the satellites and the ring gear(s). This oil is then drained away and recovered for recycling.

[0019] Another technology involves using an oil-splash gearbox. Oil is constantly present in the gearbox, which includes a sealed housing for retaining this oil. The oil level in the gearbox housing is such that at least part of the planet gears, the planet carrier, and the ring gear(s) are constantly immersed in the oil.

[0020] In a splash-jet gearbox, due to gravity, the oil flows and collects in the lower part of the housing and the gearbox. Therefore, the gear teeth located in the lower part are immersed in the oil, while the gear teeth in the upper part are not. The oil. During operation, the rotating elements inside the housing spin at high speeds and carry the oil with them. The oil tends to be centrifuged and form an oil ring inside the housing.

[0021] One of the problems of a mechanical splash gearbox is to ensure that all its gears are well lubricated.

[0022] The invention provides a simple, effective and economical solution to this problem. Summary of the invention

[0023] The invention relates to a movable ring for a mechanical splash-type reducer, particularly for aircraft, this ring having an annular shape around a longitudinal axis and comprising:

[0024] - an annular body, and

[0025] - an internal dentition,

[0026] characterized in that it further comprises at the external periphery of the body an annular row of oil scoops, these scoops being distributed around said longitudinal axis and projecting on an external annular surface of the body, each of the scoops having on the one hand a general elongated shape along the longitudinal axis and on the other hand a general curved shape along the longitudinal axis so that each of the scoops comprises a first concave lateral flank for receiving oil, and a second convex lateral flank opposite the first flank.

[0027] As mentioned above, during operation, an oil ring forms around the gearbox, and in particular around the rotating ring, if the rotational speeds are sufficient. The invention makes it possible, on the one hand, to promote the formation of this oil ring at lower rotational speeds and, on the other hand, to direct the oil flow towards points requiring lubrication. The invention makes it possible, in effect, to force the oil to move and, for example, to redirect it towards gears or bearings of the gearbox requiring lubrication. To this end, the ring includes oil scoops on its periphery. The distinctive feature of these scoops is that they have both an elongated and a curved shape, comprising a first concave side for receiving oil, and a second convex side opposite the first.The first side thus forms a hollow for receiving and carrying the oil, and the second side forms a hump whose shape can be dictated by that of the first side.

[0028] The solution proposed below is compatible with single-stage or multi-stage gearboxes. It is compatible with planetary, differential, or Wolfrom-type gearboxes. It is also compatible with spur, helical, or herringbone gears. It is compatible with all types of planet carriers, and in particular with a one-piece planet carrier. Furthermore, it is compatible with all types of bearings, whether Composed of rolling elements, a hydrodynamic bearing, etc., it is compatible with the use of the ring gear and gearbox in a turbofan engine, for example, to drive a fan or propeller. It is also compatible with the use of the ring gear and gearbox in a landing gear wheel drive system.

[0029] The crown according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0030] body. • the number of scoops is between 2 and 50; • each of the scoops has a generally elongated shape; • each of the scoops is fixed; • each of the scoops has a blade-like shape and includes an intrados forming the said first flank, an extrados forming the said second flank, as well as leading and trailing edges between which the intrados and extrados extend; • the leading edge has a greater thickness than the trailing edge; • each of the scoops has an arc-shaped form; • each of the scoops has a chevron or right-angle shape; • each of the scoops has a constant thickness along the longitudinal axis; • the scoops extend over an axial dimension measured along said axis longitudinal, which represents between 50 and 150%, and preferably between 80 and 120%, of an axial dimension of the internal teeth measured along the same axis;

[0031] — the scoops are located outside the teeth and surround the teeth;

[0032] - the external annular surface on which the scoops protrude is cylindrical, the scoops being directly located on this cylindrical surface.

[0033] The present invention also relates to a mechanical splash-type reducer, particularly for an aircraft, this reducer comprising:

[0034] - a mobile solar element rotating around a longitudinal axis,

[0035] - a first crown as described below, mounted around the solar and said longitudinal axis,

[0036] - satellites mounted between the solar system and the corona and meshed with the solar system and the crown, these satellites having axes of rotation parallel to said axis and being carried by a satellite carrier, and

[0037] - a sealed enclosure in which are located the solar, the first corona, the satellites and the satellite carrier, this enclosure containing oil so that at least part of the first ring, the satellites and the satellite carrier are immersed in this oil,

[0038] the first ring being rotatable about said longitudinal axis so that the oil scoops of this ring draw oil in during the rotation of the ring. In a Wolfrom or differential configuration, the planet carrier s is rotatable about the longitudinal axis. In a planetary configuration, the planet carrier is fixed with respect to the longitudinal axis.

[0039] Advantageously, the satellites are two-stage and comprise a first stage meshed with the first ring and the solar, and a second stage meshed with a second ring which is fixed with respect to said longitudinal axis.

[0040] The invention further relates to a turbomachine or a landing gear wheel drive system, in particular for an aircraft, comprising at least one ring gear or mechanical reducer as described above. Brief description of the figures

[0041] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0042] [Fig-1] [Fig.1] is a schematic axial cross-sectional view of a turbomachine aircraft,

[0043] [Fig.2] [Fig.2] is a partial schematic axial cross-sectional view of a planetary mechanical reducer with oil jets,

[0044] [Fig.3] [Fig.3] is a partial schematic axial cross-sectional view of a planetary mechanical bubble reducer,

[0045] [Fig.4] [Fig.4] is a partial schematic axial cross-sectional view of a Wolfrom mechanical bubble reducer,

[0046] [Fig. 5a-5b] Figures 5a and 5b show a movable crown in perspective according to a first embodiment of the invention,

[0047] [Fig.6] [Fig.6] is a view similar to that of Figure 5a and illustrates the operation of the reducer and the rotation of the ring,

[0048] [Fig. 7a-7b] Figures 7a and 7b show in perspective a variant embodiment of a crown according to the invention,

[0049] [Fig. 8a-8b] Figures 8a and 8b represent in perspective another variant of fabrication of a crown according to the invention, and

[0050] [Fig.9] [Fig.9] is a schematic perspective view of an aircraft landing gear wheel and a drive system for that wheel. Detailed description of the invention

[0051] Figure 1 describes a turbomachine 1 which conventionally comprises a blower S, a low-pressure compressor 1a, a high-pressure compressor 1b, an annular combustion chamber 1e, a high-pressure turbine 1d, a turbine The low-pressure compressor 1b and the high-pressure turbine 1d are connected by a high-pressure shaft 2 and together form a high-pressure (HP) unit. The low-pressure compressor 1a and the low-pressure turbine 1e are connected by a low-pressure shaft 3 and together form a low-pressure (LP) unit.

[0052] The blower S is driven by a blower shaft 4 which is driven in rotation with the shaft BP 3 by means of a reducer 6. This reducer 6 can be of the planetary, epicyclic or Wolfrom type for example.

[0053] Although the following description relates to a planetary or epicyclic type gearbox, it also applies to a mechanical differential in which the three components—the planet carrier, the ring gear, and the sun gear—are free to rotate, the rotational speed of one of these components depending, in particular, on the difference in speeds of the other two components. It also applies to the specific case of a two-stage Wolfrom-type gearbox.

[0054] The reducer 6 is positioned in the upstream part of the turbomachine. A fixed structure schematically comprising, here, an upstream part 5a and a downstream part 5b which make up the motor or stator housing 5 is arranged 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 passage of the blower shaft 4, and downstream by seals at the level of the passage of the BP shaft 3.

[0055] Figure 2 shows a gearbox 6 which can take the form of different architectures depending on whether certain parts are fixed or rotating. At the input, the gearbox 6 is connected to the shaft BP 3, for example via internal splines 7a. Thus, the shaft BP 3 drives a planetary gear called the sun gear 7. Conventionally, the sun gear 7, whose axis of rotation coincides with that of the turbomachine X, drives a series of gears called planet gears 8, which are 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 planet gears 8. The number of planet gears 8 is generally defined between three and seven for this type of application.

[0056] The set of satellites 8 is held by a satellite carrier 10. Each satellite 8 rotates around its own Y axis, and meshes with the ring 9.

[0057] The output we have: • In an epicyclic configuration, the set of satellites 8 drives the planet carrier 10 in rotation around the X-axis of the turbomachine. The ring gear is fixed to the motor or stator housing 5 via a ring carrier 12 and the planet carrier 10 is fixed to the fan shaft 4. • In a planetary configuration, the set of satellites 8 is held by a satellite carrier 10 which is fixed to the motor or stator housing 5. Each satellite drives the crown which is brought to the blower shaft 4 via a crown carrier 12.

[0058] Each satellite 8 is mounted to rotate freely by means of a bearing 11, for example of the rolling or hydrodynamic plain bearing type. In the case of a plain bearing, the bearing 11 comprises a bearing body 10b and the bearing bodies 10b of the different plain bearings are positioned relative to each other and are supported by walls 10a1, 10a2 of the satellite carrier 10.

[0059] The walls lOal, 10a2 have an annular shape and are perpendicular to the X axis. They are at an axial distance from each other and receive between them the bearings 11, the satellites 8 and the solar 7.

[0060] There is a number of bearings 11 equal to the number of satellites 8. For reasons of operation, assembly, manufacture, control, repair or replacement, the bearings 11 (and in particular the bearing bodies 10b) and the walls 10a1, 10a2 can be separated into several pieces.

[0061] For the same reasons mentioned above, the teeth 8d of a gearbox can be separated into several helices, each having a median plane P. In our example, we detail the operation of a multi-helix gearbox with a ring gear separated into two half-ring gears: • an upstream half-crown 9a consisting of a rim 9aa and a mounting half-flange 9ab. On the rim 9aa is the upstream helix of the reduction gear teeth. This upstream helix meshes with that of the satellite 8, which meshes with that of the solar 7. • a downstream half-crown 9b consisting of a rim 9ba and a mounting flange half 9bb. On the rim 9ba is the downstream helix of the reduction gear teeth. This downstream helix meshes with that of the satellite 8, which meshes with that of the solar 7.

[0062] If the helix widths vary between the solar 7, the satellites 8 and the crown 9 because of the tooth overlaps, they are all centered on a median plane P for the upstream helices and on another median plane P for the downstream helices.

[0063] The mounting half-flange 9ab of the upstream crown 9a and the mounting half-flange 9bb of the downstream crown 9b form the mounting flange 9c of the crown. The crown 9 is fixed to a crown carrier by assembling the mounting flange 9c of the crown and the mounting flange 12a of the crown carrier using, for example, a bolted assembly.

[0064] Alternatively, the flange 9c of the crown 9 could be replaced by grooves.

[0065] The arrows in [Fig.2] describe the flow of oil into reducer 6. The oil enters the reducer 6 from the stator section 5 into the distributor 13 by various means which will not be specified in this view as they are specific to one or more types of architecture. The distributor is generally divided into two parts, each repeated with the same number of satellites. Injectors 13a lubricate the gear teeth, and arms 13b lubricate the bearings 11. Oil is supplied to injectors 13a and exits through ends 13c to lubricate the gear teeth of the satellites 8, the solar element 7, and the ring gear 9. Oil is also supplied to arm 13b and flows through the feed port 13d of the bearing body 10b into an internal cavity 10c of the latter. The oil then flows through this cavity 10c to supply oil passages 10d to an external cylindrical guide surface of the corresponding satellite.

[0066] The reducer 6 of [Fig.2] is thus a reducer of the type with oil jets or injectors.

[0067] On the contrary, the present invention relates to a reducer of the splash-type, two examples of which are illustrated in figures 3 and 4.

[0068] In [Fig. 3], the reducer 106 is a bubble-type planetary reducer, meaning that its ring gear 109 is movable and its planet carrier s 110 is fixed. As can be seen in this figure, the reducer 106 is enclosed in a sealed housing Q.

[0069] The enclosure Q can be formed by one or more annular housings 120, 122 assembled together. Sealing is ensured by gaskets 124 or similar seals which are located, for example:

[0070] - between the casing 120, 122 of the enclosure Q and the solar element 107 or the shaft attached to the solar or coupled with solar power

[0071] - between the crown 109 or the crown carrier 112 and the housing 120, 122 of the enclosure Q.

[0072] When stationary, the oil H1 contained in the housing Q is located in the lower part of the gearbox 106 and, in particular, of the housing Q. Part of the ring gear 109, the planet gears 108, and the planet carrier 110 are immersed or bubble in this oil. During operation, a ring of oil H2 forms inside the housing Q, all around the X-axis.

[0073] In [Fig. 4], the reducer 206 is a Wolfrom splash-type reducer, that is to say, it comprises two rings 209a, 209b, namely a movable ring 209a and a fixed ring 209b. As can be seen in this figure, the reducer 206 is also enclosed in a hermetically sealed housing Q.

[0074] The satellites 208 are two-stage and comprise a first stage 208a meshed with the first ring 209a and the solar 207, and a second stage 208b meshed with a second ring 209b which is fixed with respect to said longitudinal axis X.

[0075] The enclosure Q can be formed by one or more annular housings 220, 222 assembled together. The fixed ring 209b is here fixed to the housing(s) 220, 222 of enclosure Q, and in particular intercalated between two casings 220, 222 of enclosure Q.

[0076] Sealing is ensured by annular seals 225 or similar seals which are located, for example:

[0077] - between the casing 220, 222 of the enclosure Q and the solar element 207 or the shaft attached to the solar or coupled with solar power

[0078] - between the housing 220, 222 of the enclosure Q and the movable ring 209a, and

[0079] - between the movable ring 209a and the solar element 207 or the shaft attached to the solar element or coupled with solar power,

[0080] There may also be seals between the satellite carrier 210 and the solar 207 or the shaft attached to or coupled with the solar, as well as between this solar 207 or this shaft and the movable ring 209a or the element attached in rotation to the movable ring.

[0081] The rotating moving parts are guided by roller bearings 224 which are, for example, located:

[0082] - between the housing 220, 222 of the enclosure Q and the movable ring 209a,

[0083] - between the housing 220, 222 of the enclosure and the satellite carrier 210,

[0084] - between the satellite carrier 20 and the satellites 208, and

[0085] - between the movable ring 209a and the solar element 207 or the shaft attached to the solar element or coupled with solar power.

[0086] When stationary, oil H1 is located in the lower part of the gearbox 206 and in particular in the housing Q. Part of the rings 209a, 209b, the satellites 208 and the satellite carrier 210 are immersed or bubble in this oil. During operation, a ring of oil H2 forms inside the housing Q, all around the X-axis.

[0087] The present invention relates to a movable ring 109, 209a for a mechanical gearbox 106, 206 of an aircraft. Since the ring 109, 209a is movable, the gearbox 6 can be of the planetary, differential, or Wolfrom type. Furthermore, this gearbox 106, 206 can be used in a turbomachine 1 such as that illustrated in [Fig. 1], for driving a fan S, or in another context such as in a wheel drive system for an aircraft landing gear (see [Fig. 9]).

[0088] It should be noted that the ring 109, 209a according to the invention can be the only ring of the reducer 106, as in a planetary reducer 109. Alternatively, the reducer 206 could comprise two rings, one movable ring 209a according to the invention, and one fixed ring 209b, or two movable rings according to the invention.

[0089] Figures 5a, 5b and 6 illustrate a first embodiment of a crown 109, 209a according to the invention, and figures 7a-7b and 8a-8b illustrate two other embodiments of this crown 109, 209a.

[0090] The crown 109, 209a is preferably metallic. Its main material is therefore a metallic alloy.

[0091] The crown 109, 209a has an annular shape around the X axis and comprises:

[0092] - an annular body 130,

[0093] - an internal dentition 132, for example at the internal periphery of the body 130.

[0094] The body 130 of the crown is not fully represented. The body 130 may have in axial section a general L-shape and comprise a cylindrical wall 130a one end of which is connected to a flange (as in [Fig.3]) or to a radial or frustoconical wall 130b (as in [Fig.4]).

[0095] In the example shown, the teeth 132 protrude on an internal cylindrical surface 134 of the wall 130a.

[0096] The wall 130b can be used to fix the crown 109, 209a to an element that is to be driven in rotation about the X-axis. In the case of [Fig. 3], this is the crown carrier 112 which is connected to a blower propeller, for example. In the case of [Fig. 4], this is, for example, a drive shaft for the wheel rim.

[0097] The particularity of this crown 109, 209a is that it also includes oil scoops 136 on the external periphery of the body 130.

[0098] The crown 109, 209a includes an annular row of these oil scoops 136 which are distributed around the X axis and which protrude from the external cylindrical surface 134 of the body 130.

[0099] It can be seen in the drawings that the scoops 136 are located outside the teeth 132 and surround these teeth 132.

[0100] The number of scoops 136 is for example between 2 and 50.

[0101] Each of the scoops 136 has a general elongated shape along the X axis.

[0102] Each of the scoops 136 also has a general curved shape along the X axis.

[0103] Each of the scoops 136 thus comprises a first concave lateral flank 136c of oil reception, and a second convex lateral flank 136d opposite the first flank 136c. The concave flank 136c allows more oil to be carried during operation.

[0104] Each of the scoops 136 comprises a first longitudinal end 136a and a second longitudinal end 136b. The end 136a may be located in a plane perpendicular to the axis X, which passes through a longitudinal end 132 of the teeth 132 or even through a free longitudinal end 130c of the body 130.

[0105] The scoops 136 can extend over an axial dimension L1 measured along the X axis, which represents between 50 and 150%, and preferably between 80 and 120%, of an axial dimension L2 of the toothing 130 measured along the same axis.

[0106] Each of the scoops 136 is fixed.

[0107] According to the first embodiment shown in figures 5a and 5b, each of the scoops 136 has a blade shape and includes an intrados forming said first flank 136c, and an extrados forming said second flank 136d.

[0108] Each of the scoops 136 further comprises leading and trailing edges between which the intrados and extrados extend. The leading edge is formed by the upstream end 136a and the trailing edge is formed by the downstream end 136b.

[0109] The leading edge preferably has a greater thickness than the trailing edge.

[0110] In the embodiment shown in Figures 7a and 7b, each of the scoops 136 has an arc-shaped form. Each of the scoops 136 preferably has a constant thickness along the longitudinal axis X.

[0111] In the embodiment shown in Figures 8a and 8b, each of the scoops 136 has a chevron or right-angled shape. Each of the scoops 136 preferably has a constant thickness along the longitudinal axis X.

[0112] The operation of the crown 109, 209a according to the invention is similar regardless of its embodiment. This operation is schematically represented in [Fig. 6].

[0113] During start-up and operation, the ring gear 109, 209a rotates around the X-axis, and its lower portion is immersed in the oil H1 present in the gearbox 106, 206 or arranged all around the gearbox within its housing. The scoops 136 of the ring gear 109, 209a force the oil to move (arrows T) and direct this oil in a predetermined direction, for example, towards gears to be lubricated. The gear to be lubricated is, for example, that between the planet gears and the fixed ring gear in the case of a Wolfrom-type gearbox.

[0114] Alternatively, the scoops 136 could simply collect oil from the lower part and bring it to the upper part. Once at the top, the oil could trickle down onto the components requiring lubrication.

[0115] The scoops 136 are advantageously oriented according to the direction of rotation of the ring 109, 209a.

[0116] Fig. 9 shows a drive system 310 for at least one wheel 312 of an aircraft landing gear 314.

[0117] The wheel 312 has a rim 316 which has an axis of rotation X. In a conventional manner, this rim 316 has a general tubular or disc shape and carries a tire 318 on its periphery.

[0118] The system 310 includes an electric motor 320 and a mechanical transmission system 322 between a shaft of the motor 320 and the rim 316 of the wheel 312.

[0119] In the example shown, the motor 320 and the system 322 each have a generally annular shape and are centered on the X-axis. They are arranged next to each other and The 322 system is installed between the motor 320 and the rim 316. Part of the 322 system, or even part of the 320 motor, could be housed in the rim 16 to reduce the size of the 310 system. The motor 320 and the 322 system can be protected by an external cylindrical cover 326 projecting from one side of the rim 316 or the tire 318.

[0120] The mechanical transmission system 322 includes a mechanical reducer 328 similar to the reducer 106, 206 described above and including a ring 109, 209a within the meaning of the invention.

Claims

Demands

1. A movable ring gear (109, 209a) for a mechanical splash-type reducer (106, 206), in particular for an aircraft, said ring gear (109, 209a) having an annular shape around a longitudinal axis (X) and comprising: - an annular body (130), - internal teeth (132), and - an annular row of oil scoops (136) at the external periphery of the body (130), these scoops being distributed around said longitudinal axis (X) and projecting on an external annular surface (134) of the body (130), each of the scoops (136) having on the one hand a general elongated shape along the longitudinal axis (X) and on the other hand a general curved shape along the longitudinal axis (X) such that each of the scoops includes a first concave lateral flank (136c) for receiving oil, and a second convex lateral flank (136d) opposite the first flank.

2. Crown (109, 209a) according to claim 1, wherein the number of scoops (136) is between 2 and 50.

3. Crown (109, 209a) according to claim 1 or 2, wherein each of the scoops (136) is fixed.

4. Crown (90) according to any one of claims 1 to 3, wherein each of the scoops (136) has a blade shape and comprises an intrados forming said first flank (136c), an extrados forming said second flank (136d), as well as leading and trailing edges between which the intrados and extrados extend.

5. Crown (109, 209a) according to claim 4, wherein the leading edge has a thickness greater than that of the trailing edge.

6. Crown (90) according to any one of claims 1 to 3, wherein each of the scoops (136) has an arc-shaped form.

7. Crown (90) according to any one of claims 1 to 3, wherein each of the scoops (136) has a chevron or right-angle shape.

8. Crown (109, 209a) according to claim 6 or 7, wherein each of the scoops (136) has a constant thickness along the longitudinal axis (X).

9. Crown (90) according to any one of the preceding claims, wherein the scoops (136) extend over an axial dimension (L1) measured along said longitudinal axis (X), which represents between 50 and 150%, and preferably between 80 and 120%, of an axial dimension (L2) of the internal teeth (132) measured along the same axis (X).

10. Crown (90) according to any one of the preceding claims, wherein the external annular surface (134) on which the scoops (136) project is cylindrical, the scoops (136) being directly situated on this cylindrical surface (134).

11. A mechanical, splash-type gearbox (106, 206), particularly for an aircraft, said gearbox (106, 206) comprising: - a solar element (107, 207) rotatable about a longitudinal axis (X), - a first ring gear (109, 209a) according to any one of the preceding claims, mounted around the solar element (107, 207) and said longitudinal axis (X), - satellites (108, 208) mounted between the solar element (107, 207) and the ring gear (90) and meshed with the solar element and the ring gear, these satellites (108, 208) having axes of rotation (Y) parallel to said axis (X) and being carried by a satellite carrier (110, 210), and - a sealed internal enclosure (Q) in which the solar element (107, 207), the first ring gear, and the first ring gear are located. (109, 209a), the satellites (108, 208) and the satellite carrier (110, 210), this enclosure (Q) containing oil (Hl, H2) such that at least a part of the first ring (109, 209a), the satellites (108, 208) and the satellite carrier (110,210) bubbles in this oil (H1, H2), the first ring (109, 209a) being mobile in rotation about said longitudinal axis (X) so that the oil scoops (136) of this ring (109, 209a) carry oil during the rotation of the ring (109, 209a).

12. Reducer (206) according to claim 11, wherein the satellites (208) are double-stage and comprise a first stage (208a) meshed with the first ring (209a) and the solar (207), and a second stage (208b) meshed with a second ring (209b) which is fixed with respect to said longitudinal axis (X).

13. Turbomachine (1), in particular for an aircraft, comprising at least one ring gear (109, 209a) according to any one of claims 1 to 10 or a mechanical reducer (106, 206) according to claim 11 or 12.

14. A drive system (310) for a landing gear wheel (312) (314), in particular for an aircraft, comprising at less a crown (109, 209a) according to any one of claims 1 to 10 or a mechanical reducer (106, 206) according to claim 11 or 12.

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