Fixed casing for a mechanical reducer of an aircraft

Abstract

The invention relates to a fixed casing (122, 222) for a splash-lubricated mechanical reducer (106, 206), in particular of an aircraft, the casing (122, 222) having an annular shape about a longitudinal axis (X) and comprising: - a cylindrical wall (230) extending about the axis (X) and connected to an annular attachment flange (232), this cylindrical wall (230) comprising a first internal cylindrical surface (230a); and - an annular wall (234) extending about the axis (X) and having its external periphery connected to the cylindrical wall (230), this annular wall (234) comprising a second annular surface (234a) connected to the first surface (230a), the first and second surfaces (230a, 234a) defining an annular space (E) configured to receive an oil ring (H2), characterised in that it further comprises at least one oil deflector (240) projecting on at least one of the first and second surfaces (230a, 234a).

Description

[0001] DESCRIPTION

[0002] TITLE: FIXED CASING FOR AN AIRCRAFT MECHANICAL REDUCER

[0003] Technical field of the invention

[0004] The present invention relates to a fixed casing 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-B1 -3 098 562, FR-B1 - 3 101 129, EP-A1 -2 834 503, US-A-4,864,893 and US-A-10,807,467.

[0007] 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.

[0008] New generations of dual-flow turbomachines, particularly those with a high bypass ratio, include a mechanical reducer to drive the shaft of a fan. Typically, the reducer's purpose is to transform the so-called fast rotation speed of a power turbine shaft into a slower rotation speed for the shaft driving the fan.

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

[0010] Such a reducer comprises a central pinion, called a sun gear, a crown gear and pinions called planet gears, which are meshed between the sun gear and the crown gear. The planet gears are held by a frame called a planet carrier. The sun gear, the crown gear and the planet carrier are planet gears because their axes of revolution coincide with the axis of the turbomachine or the wheel of a landing gear. The planet gears each have a different axis of revolution equally distributed over the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis X.

[0011] There are several gearbox architectures. In the state of the art, gearboxes are planetary or epicyclic. In other similar applications, there are so-called differential or "compound" architectures.

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

[0013] - 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.

[0014] - On a differential reducer, no element is fixed in rotation. The crown rotates in the opposite direction to the sun and the planet carrier.

[0015] Gearboxes can be composed of one or more meshing stages. This meshing is ensured in different ways such as by contact, friction or even magnetic fields. There are several types of contact meshing such as straight, helical or herringbone teeth.

[0016] Gearboxes can be composed of one or more meshing stages. This meshing is ensured in different ways such as by contact, friction or even magnetic fields.

[0017] A satellite may comprise one or two meshing stages. In the present application, the term "stage" or "toothing" means a series of meshing teeth with a series of complementary teeth. A toothing may be internal or external. A single-stage satellite comprises a toothing which may be straight, helical or herringbone and whose teeth are located on the same diameter. This toothing cooperates with both the sun gear and the crown. A double-stage satellite comprises two toothings or two series of teeth which are located on different diameters. A first toothing cooperates with the sun gear and a second toothing cooperates with the crown.

[0018] There is also a configuration, called Wolfrom, in which the satellites are double-stage and have a first toothing that cooperates with the sun and a crown, and a second toothing that cooperates with a second crown. The reducer thus comprises two crowns, one of which is fixed and the other mobile.

[0019] A mechanical reducer must be lubricated to ensure its operation and also to evacuate the calories generated during operation. For this, lubricating oil is used.

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

[0021] The first technology involves lubricating the gearbox using oil jets. The jets are supplied with oil and spray oil onto the gears, i.e., the teeth of the sun gear, the planet gears, and the crown(s). This oil is then drained and recovered for recycling.

[0022] Another technology is to use an oil splash reducer. The oil is permanently present in the reducer, which includes a sealed enclosure for retaining this oil. The oil level in the reducer enclosure is such that at least part of the planet gears, the planet carrier, and the crown gear(s) splash in the oil, i.e. are permanently bathed in the oil.

[0023] In a splash reducer, due to gravity, the oil flows and is stored in the lower part of the housing and the reducer. Therefore, the teeth located in the lower part are immersed in oil while the teeth in the upper part are not immersed in oil. During operation, the rotating elements contained in the housing rotate at high speeds and carry the oil. The oil tends to be centrifuged and form an oil ring inside the housing. One of the problems with a mechanical splash reducer is ensuring that all its gears are well 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 fixed casing for a mechanical splash reducer, in particular for an aircraft, this casing having an annular shape around a longitudinal axis and comprising:

[0027] - a cylindrical wall extending around the axis and connected to an annular fixing flange, this cylindrical wall comprising a first internal cylindrical surface, and

[0028] - an annular wall extending around the axis and having its outer periphery connected to the cylindrical wall, this annular wall comprising a second annular surface connected to the first surface, said first and second surfaces defining an annular space configured to receive an oil ring, in particular a splash ring, characterized in that it further comprises at least one oil deflector projecting from at least one of said first and second surfaces.

[0029] As mentioned above, during operation, an oil ring forms around the reducer and in particular inside the enclosure and the casing forming this enclosure. The oil ring is located at the annular space of the casing, on the aforementioned surfaces. The invention makes it possible to detach the oil from the casing and to divert this oil towards gears or elements to be lubricated of the reducer. For this, the casing comprises at least one oil deflector intended to be located at this oil ring.

[0030] The solution proposed below is compatible with a single-stage or multi-stage gearbox. It is compatible with a planetary, epicyclic, differential or Wolfrom type gearbox. It is also compatible with straight, helical or herringbone teeth. It is compatible with any type of planet carrier, and in particular with a single-piece planet carrier. It is also compatible with any type of bearing, whether it is composed of rolling elements, a hydrodynamic bearing, etc. It is compatible with the use of the crown and the gearbox in a double-flow turbomachine, for example to drive a fan or a propeller. It is also compatible with the use of the crown and the gearbox in a system for driving a wheel of a landing gear.

[0031] The distinction between splash lubrication and oil spray lubrication is known to a person skilled in the art, particularly in the context of a mechanical reducer. The oil ring formed in the reducer allows moving parts of the reducer to be bathed in oil and to be able to carry this oil with them as they move, for the purpose of lubricating the rest of the reducer.

[0032] The casing 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:

[0033] - the casing comprises a single deflector which is located on said first surface, or even also on said second surface;

[0034] - the deflector is located at 12 o'clock by analogy with the dial of a clock when the casing is in the position of use in which said longitudinal axis is horizontal;

[0035] - the or each deflector has a generally elongated shape, in particular along said longitudinal axis;

[0036] - the or each deflector extends from the second surface to the flange;

[0037] - the or each deflector has a generally triangular cross-sectional shape;

[0038] - the or each deflector comprises a first side oriented in the circumferential direction, which has a concave curved shape, and optionally a second side oriented in an opposite circumferential direction, which has a concave curved shape; - the sides of the or each deflector have different curved shapes and in particular curved shapes having different radii of curvature;

[0039] - the or each deflector has an arrowhead shape, one base of which is connected to the second surface and the point is located on the flange side, or conversely, the base of which is located on the flange side and the point is located on the second surface side;

[0040] - the or each deflector includes:

[0041] - two side surfaces which extend from the second surface towards the flange, and

[0042] - two end surfaces extending from the tip towards the second surface, these end surfaces being concavely curved and being connected respectively to the side surfaces to form curved edges extending from the second surface to the tip;

[0043] -- the two lateral surfaces form an angle between them greater than 90 and less than 180°, measured in a plane perpendicular to the longitudinal axis;

[0044] -- alternatively, the two lateral surfaces form an angle between them of less than 90, measured in a plane perpendicular to the longitudinal axis; these surfaces may be parallel.

[0045] The present invention also relates to a mechanical reducer, in particular for an aircraft, this reducer comprising:

[0046] - a mobile solar system rotating around a longitudinal axis,

[0047] - at least a first crown mounted around the solar and said longitudinal axis,

[0048] - satellites mounted between the sun and the crown and meshed with the sun and the crown, these satellites having axes of rotation parallel to said axis and being carried by a satellite carrier, and

[0049] - a sealed enclosure in which the solar, the crown, the satellites and the satellite carrier are located, this enclosure being formed at least in part by a casing as described above. Advantageously, the satellites are double-stage and comprise a first stage meshed with the first crown which is movable around said longitudinal axis and the solar, and a second stage meshed with a second crown which is fixed with respect to said longitudinal axis.

[0050] 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:

[0051] -- the casing is mounted in a sealed manner on the solar or a shaft integral with the solar or coupled to this solar,

[0052] -- the casing is fixed to said fixed crown, and in particular the flange of the casing is fixed to a flange of the fixed crown,

[0053] -- alternatively, in a planetary or differential configuration for example, the casing is fixed directly to a stator,

[0054] -- the casing is mounted in a sealed manner on a portion integral in rotation with said movable crown,

[0055] -- alternatively, in an epicyclic or differential configuration for example, the casing is mounted in a sealed manner on a portion integral in rotation with the planet carrier.

[0056] The invention further relates to a turbomachine or a system for driving a landing gear wheel, in particular an aircraft wheel, comprising at least one casing or mechanical reducer as described above.

[0057] Brief description of the figures

[0058] 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:

[0059] [Fig. 1] Figure 1 is a schematic axial sectional view of an aircraft turbomachine,

[0060] [Fig. 2] Figure 2 is a partial schematic axial sectional view of a planetary mechanical reducer with oil jets, [Fig. 3] Figure 3 is a partial schematic axial sectional view of a planetary mechanical reducer with splash,

[0061] [Fig. 4] Figure 4 is a partial schematic view in axial section of a Wolfrom mechanical splash reducer,

[0062] [Fig. 5] Figure 5 is another partial schematic in perspective and in axial section of a reducer comprising a fixed casing according to an embodiment of the invention,

[0063] [Fig. 6] Figure 6 is a schematic perspective view of the housing of Figure 5,

[0064] [Fig. 7] Figure 7 is a view similar to that of Figure 6 and illustrates the casing during operation of the reducer,

[0065] [Fig. 8] Figure 8 is a partial schematic view of an alternative embodiment of a casing according to the invention, and

[0066] [Fig. 9] Figure 9 is a schematic perspective view of a wheel of an aircraft landing gear and a drive system for this wheel.

[0067] Detailed description of the invention

[0068] Figure 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 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 form with it a high-pressure (HP) body. The low-pressure compressor 1a and the low-pressure turbine 1e are connected by a low-pressure shaft 3 and form with it a low-pressure (LP) body.

[0069] The blower S is driven by a blower shaft 4 which is rotated with the LP shaft 3 by means of a reducer 6. This reducer 6 can be of the planetary, epicyclic or Wolfrom type for example.

[0070] Although the following description concerns a planetary or epicyclic type reducer, it also applies to a mechanical differential in which the three components, namely the planet carrier, the crown wheel 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. It also applies to the particular case of a double-stage reducer of the Wolfrom type.

[0071] The reducer 6 is positioned in the upstream part of the turbomachine. A fixed structure comprising schematically, here, an upstream part 5a and a downstream part 5b which composes 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.

[0072] Figure 2 shows a reducer 6 which can take the form of different architectures depending on whether certain parts are fixed or rotating. At the input, the reducer 6 is connected to the LP shaft 3, for example via internal 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 is the same as that of the turbomachine X, drives a series of pinions called satellites 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 satellites 8. The number of satellites 8 is generally defined between three and seven for this type of application.

[0073] 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 crown 9.

[0074] At the output we have:

[0075] ■ in an epicyclic configuration, the set of planet gears 8 rotates the planet carrier 10 around the axis X of the turbomachine. The ring gear is fixed to the engine casing or stator 5 via a ring gear carrier 12 and the planet carrier 10 is fixed to the fan shaft 4. ■ in a planetary configuration, the set of planet gears 8 is held by a planet carrier 10 which is fixed to the engine casing or stator 5. Each planet gear drives the ring gear which is attached to the fan shaft 4 via a ring gear carrier 12.

[0076] Each satellite 8 is mounted to rotate freely using a bearing 11, for example of the rolling bearing 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 carried by walls 10a1, 10a2 of the planet carrier 10. The walls 10a1, 10a2 have an annular shape and are perpendicular to the axis X. They are axially spaced from each other and receive between them the bearings 11, the satellites 8 and the solar 7.

[0077] There are a number of bearings 11 equal to the number of satellites 8. For reasons of operation, assembly, manufacturing, 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.

[0078] For the same reasons mentioned above, the 8d toothing of a reducer can be separated into several helices, each having a median plane P. In our example, we detail the operation of a multi-helix reducer with a crown separated into two half-crowns:

[0079] ■ an upstream half-crown 9a consisting of a rim 9aa and a fixing half-flange 9ab. On the rim 9aa is the upstream helix of the gear teeth. This upstream helix meshes with that of the satellite 8 which meshes with that of the solar 7.

[0080] ■ a downstream half-crown 9b consisting of a rim 9ba and a half-fixing flange 9bb. On the rim 9ba is the downstream helix of the gear teeth. This downstream helix meshes with that of the satellite 8 which meshes with that of the solar 7.

[0081] If the propeller widths vary between the sun gear 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 propellers and on another median plane P for the downstream propellers.

[0082] The half-clamp 9ab of the upstream crown 9a and the half-clamp 9bb of the downstream crown 9b form the crown mounting flange 9c. The crown 9 is fixed to a crown carrier by assembling the crown mounting flange 9c and the crown carrier mounting flange 12a using a bolted assembly for example.

[0083] Alternatively, the flange 9c of the crown 9 could be replaced by splines.

[0084] The arrows in Figure 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 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 injectors 13a to exit through ends 13c in order to lubricate with oil the teeth of the satellites 8, the sun 7 and also the crown 9. The oil is also brought to the arm 13b and circulates via the supply mouth 13d of the bearing body 10b in an internal cavity 10c of the latter.The oil then circulates in this cavity 10c to supply oil passage orifices 10d to an external cylindrical guide surface of the corresponding satellite.

[0085] The reducer 6 of figure 2 is thus a reducer of the type with oil jets or injectors.

[0086] On the contrary, the present invention relates to a splash type reducer, two examples of which are illustrated in Figures 3 and 4.

[0087] In Figure 3, the reducer 106 is a splash planetary reducer, that is to say that its crown 109 is movable and its planet carrier 110 is fixed. As seen in this figure, the reducer 106 is enclosed in a sealed enclosure Q. The enclosure Q may be formed by one or more annular casings 120, 122 assembled together. Sealing is ensured by seals 124 or the like which are for example located:

[0088] - between the casing 120, 122 of the enclosure Q and the solar 107 or the shaft secured to the solar or coupled with the solar,

[0089] - between the crown 109 or the crown carrier 112 and the casing 120, 122 of the enclosure Q.

[0090] When stopped, the oil H1 contained in the enclosure Q is located in the lower part of the reducer 106 and in particular of the enclosure Q. A part of the crown 109, the satellites 108 and the planet carrier 110 bathe or splash in this oil. In operation, a ring of oil H2 forms inside the enclosure Q, all around the axis X.

[0091] In Figure 4, the reducer 206 is a Wolfrom splash reducer, that is, it comprises two crowns 209a, 209b, namely a movable crown 209a and a fixed crown 209b. As seen in this figure, the reducer 206 is also enclosed in a sealed enclosure Q.

[0092] The satellites 208 are double-stage and comprise a first stage 208a meshed with the first ring 209a and the sun gear 207, and a second stage 208b meshed with a second ring 209b which is fixed with respect to said longitudinal axis X.

[0093] The enclosure Q may be formed by one or more annular casings 220, 222 assembled together. The fixed crown 209b is here fixed to the casing(s) 220, 222 of the enclosure Q, and in particular interposed between two casings 220, 222 of the enclosure Q.

[0094] The seal is ensured by annular seals 225 or similar which are for example located:

[0095] - between the casing 220, 222 of the enclosure Q and the solar 207 or the shaft secured to the solar or coupled with the solar,

[0096] - between the casing 220, 222 of the enclosure Q and the movable crown 209a, and - between the movable crown 209a and the solar 207 or the shaft secured to the solar or coupled with the solar.

[0097] There may also be seals between the planet carrier 210 and the solar 207 or the shaft secured to the solar or coupled with the solar, as well as between this solar 207 or this shaft and the movable crown 209a or the element secured in rotation to the movable crown.

[0098] The rotating mobile elements are guided by rolling bearings 224 which are for example located:

[0099] - between the casing 220, 222 of the enclosure Q and the movable crown 209a,

[0100] - between the casing 220, 222 of the enclosure and the planet carrier 210,

[0101] - between the satellite carrier 20 and the satellites 208, and

[0102] - between the mobile crown 209a and the solar 207 or the shaft secured to the solar or coupled with the solar.

[0103] When stopped, the oil H1 is located in the lower part of the reducer 206 and in particular of the enclosure Q. A part of the crowns 209a, 209b, the satellites 208 and the planet carrier 210 are immersed or splashed in this oil. In operation, a ring of oil H2 forms inside the enclosure Q, all around the axis X.

[0104] The present invention relates to a fixed casing 122, 222 for an aircraft mechanical reducer 106, 206. Insofar as the casing 122, 222 is fixed, the reducer 106, 206 may be of the planetary, epicyclic, differential or Wolfrom type. Furthermore, this reducer 106, 206 may 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 system for driving a wheel for an aircraft landing gear (see FIG. 9).

[0105] Figures 5 to 7 illustrate a first embodiment of a casing 122, 222 according to the invention, and Figure 8 illustrates an alternative embodiment of this casing. The casing 122, 222 is preferably metallic. Its main material is therefore a metal alloy.

[0106] In Figure 5, it can be seen that the casing 122, 222 at least partially delimits the enclosure Q which surrounds and encloses the rest of the reducer, this enclosure Q being sealed and containing oil for splashing the reducer. In this enclosure Q, the solar 107, 207, the satellites 108, 208, the crown(s) 109, 209a, 209b are located depending on the configuration of the reducer 106, 206, and the planet carrier 110, 210 (not visible in Figure 5), as mentioned above.

[0107] The housing 122, 222 has an annular shape around the X axis and comprises:

[0108] - a cylindrical wall 230 extending around the axis X and connected to an annular fixing flange 232, this cylindrical wall 230 comprising a first internal cylindrical surface 230a, and

[0109] - an annular wall 234 extending around the axis X and having its external periphery connected to the cylindrical wall 230, this annular wall 234 comprising a second annular surface 234a connected to the first surface 230a.

[0110] The flange 232 of the casing 122, 222 is attached to a flange of the fixed ring 209b and could be attached to a flange of another casing of the enclosure, such as the casing 120 of Figure 3.

[0111] The first and second surfaces 230a, 234a define an annular space E configured to receive the aforementioned oil ring H2.

[0112] In the example shown, the casing 122, 222 has a general L-shaped section, its annular wall 234 being a radial wall. Alternatively, the wall 234 could be a frustoconical wall.

[0113] As also mentioned above, the casing 122, 222 could be mounted on other elements of the reducer in a sealed manner by means of seals (see figures 3 and 4).

[0114] According to the invention, the housing 122, 222 comprises at least one oil deflector 240 projecting from at least one of the first and second surfaces 230a, 234a. In the embodiments illustrated in the drawings, the housing 122, 222 comprises a single deflector 240 which is located essentially on the first surface 230a. However, it can be seen that the deflector 240 is connected to the second surface 234a.

[0115] In the examples shown, the deflector 240 is located at 12 o'clock by analogy with the dial of a clock when the casing 122, 222 is in the position of use in which its longitudinal axis X is horizontal.

[0116] The deflector 240 has a generally elongated shape, in particular along the longitudinal axis X. In the examples shown, it extends axially from the second surface 234a to the flange 232.

[0117] The or each deflector 240 may have a generally triangular cross-sectional shape, as illustrated in Figures 5 to 7

[0118] The deflector 240 may comprise a first side 240a oriented in a circumferential direction, which has a concave curved shape, and optionally a second side 240b oriented in an opposite circumferential direction, which has a concave curved shape (Figure 6).

[0119] The sides 240a, 240b of the or each deflector 240 may have identical or, on the contrary, different curved shapes, and in particular curved shapes having different radii of curvature. These radii of curvature may be chosen according to the direction of rotation of the oil in the ring H2.

[0120] Alternatively, the deflector 240 may have an arrowhead shape with a base 240c connected to the second surface 234a and the tip 240d located on the side of the flange 232, as illustrated in the alternative embodiment of FIG. 8.

[0121] In the example shown, the deflector 240 may comprise:

[0122] - two lateral surfaces 240e, 240f which extend from the second surface 234a towards the flange 232, these surfaces 240e, 240f forming between them an angle a greater than 90° and less than 180°, measured in a plane perpendicular to the longitudinal axis X, and - two end surfaces 240g, 240h which extend from the tip 240d towards the second surface 234a, these end surfaces 240g, 240h being concavely curved and being connected respectively to the lateral surfaces to form curved edges 242 extending from the second surface 234a to the tip 240d.

[0123] Alternatively, the surfaces 240e, 240f could form an angle a between them of less than 90°, or even down to 0°. In the latter case, these surfaces would be parallel.

[0124] The operation of the casing 122, 222 according to the invention is similar regardless of its embodiment. This operation is schematically represented in Figure 7.

[0125] During operation of the reducer 106, 206, an oil ring H2 forms in the reducer 106, 206 and in particular in the enclosure Q, between the surfaces 230a, 234a.

[0126] In this ring H2, the oil is rotated by the crown 109 or the movable crown 209a (arrow F1). This rotating oil reaches the deflector 240 which modifies its trajectory and detaches it from the surface 230a, or even from the surface 234a. The oil is then deflected in a predetermined direction, for example towards gears to be lubricated (arrows F2). The gearing to be lubricated is for example that between the satellites 108, 208 and the crown(s) 109, 209a, 209b.

[0127] Although the preceding examples illustrate a baffle 240 located at the top of the housing 122, 222, it is possible to position it anywhere around the housing 122, 222, as needed. It is also possible to add multiple instances of these baffles 240.

[0128] On the other hand, although the illustrations are based on a Wolfrom type reducer casing 122, 222, this solution is compatible with all the types of reducers described in the introduction (epicyclic, planetary, Wolfrom, etc.), single stage or multi-stage. Figure 9 shows a system 310 for driving at least one wheel 312 of an aircraft landing gear 314.

[0129] The wheel 312 comprises a rim 316 which has an axis of rotation X. Conventionally, this rim 316 has a generally tubular or disc shape and carries a tire 318 at its periphery.

[0130] The system 310 comprises 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.

[0131] 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 system 322 is installed between the motor 320 and the rim 316. A part of the system 322, or even also a part of the motor 320, could be housed in the rim 16 to reduce the size of the system 310. The motor 320 and the system 322 can be protected by an external cylindrical cover 326 projecting on one side of the rim 316 or the tire 318.

[0132] The mechanical transmission system 322 comprises a mechanical reducer 328 similar to the reducer 106, 206 described above and including a casing 122, 222 within the meaning of the invention.

Claims

CLAIMS 1. Fixed casing (122, 222) for a mechanical splash reducer (106, 206), in particular for an aircraft, this casing (122, 222) having an annular shape around a longitudinal axis (X) and comprising: - a cylindrical wall (230) extending around the axis (X) and connected to an annular fixing flange (232), this cylindrical wall (230) comprising a first internal cylindrical surface (230a), and - an annular wall (234) extending around the axis (X) and having its external periphery connected to the cylindrical wall (230), this annular wall (234) comprising a second annular surface (234a) connected to the first surface (230a), said first and second surfaces (230a, 234a) defining an annular space (E) configured to receive a splash oil ring (H2), characterized in that it further comprises at least one oil deflector (240) projecting on at least one of said first and second surfaces (230a, 234a).

2. Housing (122, 222) according to claim 1, wherein it comprises a single deflector (240) which is located on said first surface (230a).

3. Housing (122, 222) according to claim 2, in which the deflector (240) is located at 12 o'clock by analogy with the dial of a clock when the housing (122, 222) is in the position of use in which said longitudinal axis is horizontal.

4. Housing (122, 222) according to one of the preceding claims, in which the or each deflector (240) has a generally elongated shape, in particular along said longitudinal axis (X).

5. Housing (122, 222) according to one of the preceding claims, in which the or each deflector (240) extends from the second surface (234a) to the flange (232).

6. Housing (122, 222) according to one of claims 1 to 4, in which the or each deflector (240) has a generally triangular cross-sectional shape.

7. Housing (122, 222) according to one of claims 1 to 5, wherein the or each deflector (240) comprises a first side (240a) oriented in the circumferential direction, which has a concave curved shape, and optionally a second side (240b) oriented in an opposite circumferential direction, which has a concave curved shape.

8. Housing (122, 222) according to claim 6, wherein the sides (240a, 240b) of the or each deflector (240) have different curved shapes and in particular curved shapes having different radii of curvature.

9. Housing (122, 222) according to one of claims 1 to 4, in which the or each deflector (240) has an arrowhead shape of which a base (240c) is connected to the second surface and the point (240d) is located on the side of the flange (232), or conversely of which the base is located on the side of the flange and the point is located on the side of the second surface.

10. A housing (122, 222) according to claim 9, wherein the or each deflector (240) comprises: - two lateral surfaces (240e, 240f) which extend from the second surface (234a) towards the flange (232), these surfaces (240e, 240f) forming between them an angle (a) greater than 90 and less than 180°, measured in a plane perpendicular to the longitudinal axis (X), and - two end surfaces (240g, 240h) which extend from the tip (240d) towards the second surface (234a), these end surfaces (240g, 240h) being concavely curved and being respectively connected to the side surfaces to form curved edges (242) extending from the second surface (234a) to the tip (240d).

11. Mechanical reducer (106, 206), in particular for an aircraft, this reducer (106, 206) comprising: - a solar (107, 207) mobile in rotation around a longitudinal axis (X), - at least one first crown (109, 209a) mounted around the solar (7) and said longitudinal axis (X), - satellites (108, 208) mounted between the sun gear (107, 207) and the crown gear (109, 209a) and meshed with the sun gear and the crown gear, these satellites (108, 208) having axes of rotation (Y) parallel to said axis (X) and being carried by a planet carrier (110, 210), and - a sealed enclosure (Q) in which the solar (107, 207), the crown (109, 209a), the satellites (108, 208) and the satellite carrier (110, 210) are located, this enclosure (Q) being formed at least in part by a casing (122, 222) according to one of the preceding claims.

12. Reducer (106, 206) according to claim 11, wherein the satellites (108, 208) are double-stage and comprise a first stage meshed with the first crown which is movable around said longitudinal axis and the sun (107, 207), and a second stage meshed with a second crown (209b) which is fixed with respect to said longitudinal axis (X).

13. Turbomachine (1), in particular for an aircraft, comprising at least one casing (122, 222) according to 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 casing (122, 222) according to one of claims 1 to 10 or a mechanical reducer (106, 206) according to claim 11 or 12.

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