Mobile ring gear for a mechanical reduction gear of an aircraft

Abstract

The invention relates to a mobile ring gear (109, 209a) for a splash-lubricated mechanical reduction gear (106, 206), in particular for an aircraft, said ring gear (109, 209a) having an annular shape about a longitudinal axis (X) and comprising: - an annular body (130), and - an inner toothing (132), characterised in that it further comprises, on the outer circumference of the body (130), an annular row of oil scoops (136), said scoops (136) being distributed around the longitudinal axis (X) and projecting from an outer annular surface (134) of the body (130).

Description

[0001] DESCRIPTION

[0002] TITLE: MOVING CROWN FOR AN AIRCRAFT MECHANICAL REDUCER

[0003] Technical field of the invention

[0004] 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.

[0005] Technical background

[0006] 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.

[0007] The role of a mechanical reducer is to modify the speed and torque ratio between the input and output shafts of a mechanical system.

[0008] Newer generations of turbofan engines, particularly those with a high bypass ratio, incorporate a mechanical gearbox to drive the fan shaft. Typically, the gearbox's purpose is to transform the high rotational speed of the power turbine shaft into a slower rotational speed for the fan shaft.

[0009] A wheel drive system for a landing gear may further include a mechanical reducer, as proposed by the Applicant in document EP-A1-3 882 136.

[0010] 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 the 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 X-axis.

[0011] There are several gearbox architectures. State-of-the-art gearboxes are of the planetary or epicyclic type. In other similar applications, there are also differential or compound architectures.

[0012] - On a planetary reducer, the planet carrier is fixed and the ring forms the output shaft of the device which rotates in the opposite direction to the sun.

[0013] - On an epicyclic reducer, the ring is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar.

[0014] - On a differential gearbox, no element is fixed in rotation. The ring rotates in the opposite direction to the solar and satellite carrier.

[0015] Gearboxes can consist of one or more meshing stages. This meshing is achieved in various ways, such as by contact, friction, or magnetic fields. Several types of contact meshing exist, including spur, helical, and herringbone gears.

[0016] Gearboxes can consist of one or more meshing stages. This meshing is achieved in various ways, such as by contact, friction, or magnetic fields.

[0017] A satellite may comprise one or two gear stages. In this application, "stage" or "gear set" means a series of meshing teeth with a series of complementary teeth. A gear set may be internal or external. A single-stage satellite comprises a gear set that may be straight, helical, or chevron-shaped, and whose teeth are located on the same diameter. This gear set cooperates with both the sun gear and the crown gear. A double-stage satellite comprises two gear sets or two series of teeth located on different diameters. One gear set cooperates with the sun gear, and a second gear set cooperates with the crown gear.

[0018] There is also a configuration, called Wolfrom, in which the satellites are double-staged and have a first set of teeth that cooperate with the sun gear and a ring gear, and a second set of teeth that cooperates with a second ring gear. The reduction gear thus comprises two ring gears, one of which is fixed and the other movable.

[0019] A mechanical gearbox must be lubricated to ensure its operation and also to dissipate the heat generated during operation. For this purpose, lubricating oil is used.

[0020] There are two lubrication technologies for a mechanical reducer.

[0021] The first technology involves lubricating the gearbox with oil jets. The jets are supplied with oil and spray oil onto the gears, that is, the teeth of the solar cell, the satellites, and the ring gear(s). This oil is then drained away and collected for recycling.

[0022] Another technology involves using an oil-splash gearbox. Oil is constantly present in the gearbox, which includes a sealed oil retention chamber. The oil level in the gearbox chamber is such that at least part of the planet gears, the planet carrier, and the ring gear(s) are constantly immersed in oil.

[0023] In a splash lubrication gearbox, the oil flows and collects in the lower part of the housing and the gearbox due to gravity. Therefore, the gears in the lower part are immersed in oil, while those in the upper part are not. During operation, the rotating elements inside the housing spin at high speeds, carrying the oil with them. The oil tends to be centrifugal, forming an oil ring inside the housing. One of the challenges of a mechanical splash lubrication gearbox is ensuring that all its gears are properly lubricated.

[0024] The invention provides a simple, effective and economical solution to this problem.

[0025] Summary of the invention

[0026] The invention relates to a movable ring for a mechanical splash-type gearbox, particularly for aircraft, this ring having an annular shape around a longitudinal axis and comprising:

[0027] - an annular body, and

[0028] - an internal toothing, 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.

[0029] As mentioned above, during operation, an oil ring forms around the gearbox, and particularly around the rotating ring, if the rotational speeds are sufficient. The invention allows, firstly, for the formation of this oil ring to be promoted at lower rotational speeds and, secondly, for the oil flow to be directed towards points requiring lubrication. The invention effectively forces the oil to move and, for example, to be redirected towards gears or bearings in the gearbox that require lubrication. To achieve this, the ring incorporates 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 bump whose shape can be imposed by that of the first side.

[0030] 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 monobloc planet carrier. Furthermore, it is compatible with all types of bearings, whether composed of rolling elements, hydrodynamic bearings, 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.

[0031] The crown according to the invention may comprise one or more of the following features, taken individually from each other, or in combination with each other: body.

[0032] - the number of scoops is between 2 and 50;

[0033] - each of the scoops has a generally elongated shape;

[0034] - each of the scoops is fixed;

[0035] - 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;

[0036] - the leading edge has a greater thickness than the trailing edge;

[0037] - each of the scoops has an arc-shaped form;

[0038] - each of the scoops has a chevron or right-angle shape;

[0039] - each of the scoops has a constant thickness along the longitudinal axis;

[0040] - the scoops extend over an axial dimension measured along said longitudinal axis, 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;

[0041] -- the scoops are located outside the teeth and surround the teeth;

[0042] - the external annular surface on which the scoops protrude is cylindrical, the scoops being directly situated on this cylindrical surface.

[0043] The present invention also relates to a mechanical splash-type reducer, particularly for an aircraft, this reducer comprising:

[0044] - a mobile solar panel rotating around a longitudinal axis,

[0045] - a first ring as described below, mounted around the solar element and said longitudinal axis,

[0046] - satellites mounted between the sun and the corona and meshed with the sun and the corona, these satellites having axes of rotation parallel to said axis and being carried by a satellite carrier, and

[0047] - at least one housing defining a sealed enclosure in which the solar array, the first ring, the satellites, and the satellite carrier are located, this enclosure containing oil such that at least a portion of the first ring, the satellites, and the satellite carrier are immersed in this oil, 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 satellite carrier is rotatable about the longitudinal axis. In a planetary configuration, the satellite carrier is fixed with respect to the longitudinal axis.

[0048] Advantageously, the satellites are two-stage and include a first stage meshed with the first ring and the solar system, and a second stage meshed with a second ring which is fixed with respect to said longitudinal axis.

[0049] 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.

[0050] Brief description of the figures

[0051] 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:

[0052] [Fig.1] Figure 1 is a schematic axial cross-sectional view of an aircraft turbomachine,

[0053] [Fig.2] Figure 2 is a partial schematic axial cross-sectional view of a planetary mechanical reducer with oil jets,

[0054] [Fig.3] Figure 3 is a partial schematic axial cross-sectional view of a planetary mechanical bubble reducer,

[0055] [Fig.4] Figure 4 is a partial schematic axial cross-sectional view of a Wolfrom mechanical bubble reducer,

[0056] [Fig. 5a-5b] Figures 5a and 5b show in perspective a movable crown according to a first embodiment of the invention,

[0057] [Fig. 6] Figure 6 is a view similar to that of Figure 5a and illustrates the operation of the reducer and the rotation of the ring gear.

[0058] [Fig. 7a-7b] Figures 7a and 7b show in perspective a variant embodiment of a crown according to the invention,

[0059] [Fig. 8a-8b] Figures 8a and 8b show in perspective another variant of an embodiment of a crown according to the invention, and

[0060] [Fig.9] Figure 9 is a schematic perspective view of an aircraft landing gear wheel and a drive system for that wheel.

[0061] Detailed description of the invention

[0062] Figure 1 depicts a turbomachine 1 which conventionally comprises 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 1e, and an exhaust nozzle 1h. The high-pressure compressor 1b and the high-pressure turbine 1d are connected by a high-pressure shaft 2 and together form a high-pressure (HP) housing. 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) housing.

[0063] The blower S is driven by a blower shaft 4 which is driven in rotation with the BP shaft 3 by means of a reducer 6. This reducer 6 can be of the planetary, epicyclic or Wolfrom type for example.

[0064] Although the following description concerns a planetary or epicyclic gearbox, it also applies to a mechanical differential in which the three components—the planet carrier, the ring gear, and the sun gear—are rotationally mobile, 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 gearbox of the Wolfrom type.

[0065] The gearbox 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 gearbox 6. This enclosure E is 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.

[0066] Figure 2 shows a gearbox 6 which can take on different forms 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. Typically, the sun gear 7, whose axis of rotation coincides with that of the turbomachine X, drives a series of gears called sun 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 sun gears 8. The number of sun gears 8 is generally defined between three and seven for this type of application.

[0067] 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.

[0068] Our output is:

[0069] ■ 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.

[0070] ■ 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 ring which is brought to the blower shaft 4 via a ring carrier 12.

[0071] Each satellite 8 is mounted to rotate freely using a bearing 11, for example, a rolling bearing or a hydrodynamic plain bearing. In the case of a plain bearing, the bearing 11 comprises a bearing body 10b, and the bearing bodies 10b of the various plain bearings are positioned relative to each other and are supported by walls 10a1, 10a2 of the satellite carrier 10. The walls 10a1, 10a2 have an annular shape and are perpendicular to the X-axis. They are axially spaced from each other and receive between them the bearings 11, the satellites 8, and the solar array 7.

[0072] 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 parts.

[0073] For the same reasons mentioned previously, the gear teeth 8d of a reduction gear can be separated into several helices, each with a median plane P. In our example, we detail the operation of a multi-helix reduction gear with a ring gear divided into two half-rings: ■ an upstream half-ring 9a consisting of a rim 9aa and a mounting flange half 9ab. The upstream helix of the reduction gear teeth is located on the rim 9aa. This upstream helix meshes with that of the satellite gear 8, which meshes with that of the solar gear 7.

[0074] ■ a downstream half-crown 9b consisting of a rim 9ba and a mounting half-flange 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.

[0075] Although 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.

[0076] The mounting half-flange 9ab of the upstream sprocket 9a and the mounting half-flange 9bb of the downstream sprocket 9b form the mounting flange 9c of the sprocket. The sprocket 9 is fixed to a sprocket carrier by assembling the mounting flange 9c of the sprocket and the mounting flange 12a of the sprocket carrier using, for example, a bolted assembly.

[0077] Alternatively, the flange 9c of the crown 9 could be replaced by grooves.

[0078] The arrows in Figure 2 describe the oil flow within the gearbox 6. The oil enters the gearbox 6 from the stator section 5 into the distributor 13 via various means, which will not be detailed in this view as they are specific to one or more types of architecture. The distributor is generally divided into two parts, each typically repeated with the same number of planets. The injectors 13a lubricate the gear teeth, and the arms 13b lubricate the bearings 11. The oil is supplied to the injectors 13a and exits through the ends 13c to lubricate the gear teeth of the planets 8, the sun gear 7, and the ring gear 9. The oil is also supplied to the arm 13b and flows through the feed port 13d of the bearing body 10b into an internal cavity 10c within the latter.The oil then circulates in this cavity 10c to supply oil passage orifices 10d to an external cylindrical surface for guiding the corresponding satellite.

[0079] The reducer 6 in Figure 2 is therefore a reducer of the type with oil jets or injectors.

[0080] 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.

[0081] In Figure 3, the reducer 106 is a splash-type planetary reducer, meaning that its ring gear 109 is movable and its planet carrier 110 is fixed. As can be seen in this figure, the reducer 106 is enclosed in a sealed housing Q.

[0082] 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:

[0083] - between the casing 120, 122 of the enclosure Q and the solar element 107 or the shaft attached to or coupled with the solar element,

[0084] - between the crown 109 or the crown carrier 112 and the casing 120, 122 of the enclosure Q.

[0085] When stationary, the oil H1 contained in the housing Q is located in the lower part of the gearbox 106 and, in particular, within the housing Q. Part of the ring gear 109, the planetary gears 108, and the planetary 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.

[0086] In Figure 4, the reducer 206 is a Wolfrom splash-type reducer, meaning it comprises two rings 209a, 209b, namely a moving 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.

[0087] The satellites 208 are two-stage and comprise a first stage 208a meshed with the first ring 209a and the solar element 207, and a second stage 208b meshed with a second ring 209b which is fixed with respect to the longitudinal axis X. 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 the enclosure Q, and in particular interposed between two housings 220, 222 of the enclosure Q.

[0088] Sealing is ensured by 225 annular seals or similar, which are located, for example:

[0089] - between the casing 220, 222 of enclosure Q and the solar element 207 or the shaft attached to or coupled with the solar element,

[0090] - between the housing 220, 222 of enclosure Q and the movable ring 209a, and

[0091] - between the movable ring 209a and the solar element 207 or the shaft attached to the solar element or coupled with the solar element,

[0092] In addition, there may 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 moving ring 209a or the rotating element attached to the moving ring.

[0093] The rotating moving parts are guided by roller bearings 224 which are located, for example:

[0094] - between the housing 220, 222 of enclosure Q and the movable ring 209a,

[0095] - between the housing 220, 222 of the enclosure and the satellite carrier 210,

[0096] - between the satellite carrier 20 and the satellites 208, and

[0097] - between the movable crown 209a and the solar 207 or the tree attached to the solar or coupled with the solar.

[0098] 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.

[0099] The present invention relates to a movable ring gear 109, 209a for a mechanical gearbox 106, 206 of an aircraft. Since the ring gear 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 Figure 1, for driving a fan S, or in another context such as in a wheel drive system for an aircraft landing gear (see Figure 9).

[0100] 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.

[0101] 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.

[0102] The 109, 209a crown is preferably metallic. Its main material is therefore a metallic alloy.

[0103] The 109,209a crown has an annular shape around the X-axis and comprises:

[0104] - an annular body 130,

[0105] - an internal toothing 132, for example at the internal periphery of the body 130. The body 130 of the crown is not fully shown. The body 130 may have in axial section a general L-shape and include a cylindrical wall 130a, one end of which is connected to a flange (as in Figure 3) or to a radial or frustoconical wall 130b (as in Figure 4).

[0106] In the example shown, the teeth 132 protrude from an internal cylindrical surface 134 of the wall 130a.

[0107] Wall 130b can be used to fix the crown 109, 209a to an element that must be driven in rotation around the X-axis. In the case of Figure 3, this is the crown carrier 112 which is connected to a blower propeller, for example. In the case of Figure 4, it is, for example, a drive shaft for the wheel rim.

[0108] The special feature of this crown 109, 209a is that it also includes oil scoops 136 on the outer periphery of the body 130.

[0109] 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.

[0110] It can be seen in the drawings that the scoops 136 are located outside the teeth 132 and surround these teeth 132.

[0111] The number of scoops 136, for example, is between 2 and 50.

[0112] Each of the scoops 136 has a generally elongated shape along the X axis. Each of the scoops 136 also has a generally curved shape along the X axis.

[0113] Each of the scoops 136 thus comprises a first concave lateral flank 136c for receiving oil, and a second convex lateral flank 136d opposite the first flank 136c. The concave flank 136c allows more oil to be carried during operation.

[0114] Each of the scoops 136 comprises a first longitudinal end 136a and a second longitudinal end 136b. The end 136a can 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.

[0115] 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 teeth 130 measured along the same axis.

[0116] Each of the 136 scoops is fixed.

[0117] According to the first embodiment shown in Figures 5a and 5b, each of the scoops 136 has a blade-like shape and comprises an intrados forming the first flank 136c, and an extrados forming the second flank. 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.

[0118] The leading edge preferably has a greater thickness than the trailing edge.

[0119] 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.

[0120] 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.

[0121] The operation of the crown 109, 209a according to the invention is similar regardless of its embodiment. This operation is schematically represented in Figure 6.

[0122] During startup 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 around the gearbox within its housing. The scoops 136 of the ring gear 109, 209a force the oil to move (arrows T) and direct it in a predetermined direction, for example, towards gears to be lubricated. The gear to be lubricated is, for example, the one between the planet gears and the fixed ring gear in a Wolfrom-type gearbox.

[0123] Alternatively, the scoops 136 could simply collect oil from the lower section and bring it to the upper section. Once at the top, the oil could then flow over the components requiring lubrication.

[0124] The scoops 136 are advantageously oriented according to the direction of rotation of the ring 109, 209a. Figure 9 shows a drive system 310 for at least one wheel 312 of an aircraft landing gear 314.

[0125] 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.

[0126] 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.

[0127] 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 positioned side by side, and the system 322 is installed between the motor 320 and the rim 316. Part of the system 322, or even part of the motor 320, could be housed within the rim 16 to reduce the overall size of the system 310. The motor 320 and the system 322 can be protected by an external cylindrical cover 326 projecting from one side of the rim 316 or the tire 318.

[0128] 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. Movable ring (109, 209a) for a mechanical splash-type reducer (106, 206), particularly for an aircraft, this ring (109, 209a) having an annular shape around a longitudinal axis (X) and comprising: - an annular body (130), - an internal dentition (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) so 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, in which 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. Mechanical gearbox (106, 206) with splashing action, particularly for an aircraft, this gearbox (106, 206) comprising: - a solar element (107, 207) that rotates around a longitudinal axis (X), - a first ring (109, 209a) according to 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 corona (90) and meshed with the solar element and the corona, these satellites (108, 208) having axes of rotation (Y) parallel to said axis (X) and being carried by a satellite carrier (110, 210), and - at least one housing (120, 122) defining a sealed internal enclosure (Q) in which the solar array (107, 207), the first ring (109, 209a), the satellites (108, 208), and the satellite carrier (110, 210) are located, this enclosure (Q) containing oil (H1, H2) such that at least a portion 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 rotatable about said longitudinal axis (X) so that the oil scoops (136) of this ring (109, 209a) cause oil to flow during rotation of the crown (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. Drive system (310) for a wheel (312) of landing gear (314), 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.

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