Mechanical reduction gear for an aircraft turbine engine

Abstract

The invention relates to a mechanical reduction gear (10) for an aircraft turbine engine (1), the reduction gear comprising: - a sun gear (11), - a ring gear (14), - planet gears (12) rotatably guided by bearings (8) and meshed with the sun gear (11) and the ring gear (14), and - a planet carrier (213) comprising a cage (220) in which the sun gear (11) and the planet gears (12) and the bearings (8) thereof are mounted, the cage (220) comprising an annular row of slots (300) which extend in the radial direction and each have a U-shaped opening on the outer periphery of the cage (220).

Description

[0001] DESCRIPTION

[0002] TITLE: MECHANICAL REDUCTION GEAR FOR AN AIRCRAFT TURBOMACHINE

[0003] Technical field of the invention

[0004] The present invention relates to a mechanical reducer for an aircraft turbomachine, as well as a turbomachine comprising such a reducer.

[0005] Technical Downstream Plan

[0006] The state of the art includes in particular documents FR-A1-2 987 416, FRAI -2 853 382, ​​FR-A1-3 041 054, FR-A1-3 073 915, FR-A1-3 084 428, CN-A-116 292 857, FR-A2-3 084 428 and FR-A1-3 073 915.

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

[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] Such a gearbox 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 longitudinal axis of the turbomachine. The planet gears each have a different axis of revolution and are evenly spaced around the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis of the turbomachine. Several gearbox architectures exist. In state-of-the-art turbomachinery, gearboxes are of the planetary or epicyclic type. In other similar applications, differential or compound architectures exist.

[0010] - 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.

[0011] - 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.

[0012] - On a differential gearbox, no element is fixed in rotation. The ring rotates in the opposite direction to the solar and satellite carrier.

[0013] Gearboxes can consist of one or more meshing stages. This meshing is achieved in various ways, such as by contact, friction, or magnetic field. There are several types of contact meshing, such as with spur or herringbone teeth.

[0014] The satellite carrier can be a single unit comprising a cage with an internal cavity housing the solar array, the satellites, and their guidance bearings. The solar array has internal splines for coupling to a first shaft of the turbomachine, and the crown carrier or satellite carrier is coupled to another shaft.

[0015] During operation, the planet carrier is subjected to forces that tend to deform it. This is the case for a one-piece planet carrier or a cage-and-cage type. These deformations cause the planets to tilt, leading to a degradation of the meshing and the risk of an asymmetrical oil film forming when using plain or hydrodynamic planetary guidance bearings, or the risk of roller tilting when using roller bearings for planetary guidance. These forces and deformations must be rebalanced to limit or even eliminate these effects. Planetary misalignment is an important point to monitor in order to avoid excessive loads on the gear teeth. To this end, the planet carrier design can be optimized for flexibility to reduce or even eliminate this misalignment.In particular, it has already been proposed to integrate flexibility zones into the satellite carrier cage.

[0016] The present invention offers a solution to this need, which is simple, effective and economical.

[0017] Summary of the invention

[0018] The invention relates to a mechanical gearbox for an aircraft turbomachine, this gearbox comprising:

[0019] - a solar panel centered on a central axis,

[0020] - a corona centered on the central axis and extending around the sun,

[0021] - satellites guided in rotation by bearings centered on bearing axes that are parallel to the central axis, the satellites being meshed with the sun and the corona, and

[0022] - a satellite carrier comprising a cage in which the solar array and the satellites and their bearings are mounted, the cage being formed in one piece with a cage support which has a portion-tree shape and the cage comprising:

[0023] - a first disc centered on the central axis and extending perpendicularly to this central axis, this first disc having first bearing holes centered respectively on the bearing axes and which are suitable for receiving first longitudinal ends of the bearings,

[0024] - a second disc centered on the central axis and extending parallel and axially at a distance from the first disc, this second disc having second bearing ports which are respectively centered on the bearing axes and which are suitable for receiving second longitudinal ends of the bearings, and

[0025] - bridges which extend between the first and second discs and connect them together, the bridges being separated circumferentially from each other by openings intended to be crossed by the satellites for the purpose of their meshing with the ring, characterized in that the cage has around the central axis an annular row of lights which extend in a radial direction from the outer periphery of the cage to the inner periphery of the cage, the opening of each of the lights at the outer periphery of the cage having a general U-shape and comprising a median and straight part formed in the first disc and extending axially next to one of the openings in a plane perpendicular to the central axis, and two lateral parts formed respectively in two adjacent bridges.

[0026] To give flexibility to the cage of the satellite carrier which is of the monobloc type, the invention thus proposes lights of particular shape at the level of one of its discs and next to the openings for passage of the satellites.

[0027] The present invention is compatible with:

[0028] - of a multi-stage reducer;

[0029] - of an epicycloidal or differential reducer;

[0030] - with straight or herringbone teeth.

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

[0032] - the lateral parts of each of the lights are perpendicular to the middle part of that light and extend respectively in two planes passing through the central axis;

[0033] - the cage includes on its inner periphery an annular groove which extends around the central axis and opens radially inwards, this annular groove being in communication with the lights and in particular with their median parts;

[0034] - the annular groove has an external diameter which is greater than the smallest diameter of a circumference centered on the central axis and passing through the first orifices of the first disc, and which is preferably less than the largest diameter of a circumference centered on the central axis and passing through the first orifices of the first disc;

[0035] - the annular throat has an external diameter that is greater than an internal diameter of the lumen;

[0036] - the annular groove has an internal diameter which is less than the smallest diameter of a circumference centered on the central axis and passing through the first orifices of the first disc;

[0037] - the lateral parts of each of the lights open onto the inner periphery of the bridges;

[0038] - each of the bridges includes on its two sides respectively two orifices formed by the openings of two lateral parts of two adjacent lights;

[0039] - each of the bridges includes on its inner periphery a single orifice formed by the openings of two lateral parts of two adjacent lights;

[0040] -- this single opening has a general O shape;

[0041] - each of the bridges includes on its inner periphery two orifices formed by the openings of two lateral parts of two adjacent lights;

[0042] - the two openings of each of the bridges are symmetrical with respect to a plane passing through the central axis and the middle of the corresponding bridge;

[0043] - the two openings of each of the bridges each have a bean shape, i.e. curved, and / or each have an elongated shape along the central axis;

[0044] - the orifice(s) of the bridge(s) is / are at an axial distance from the annular groove and / or is / are at a circumferential distance from the annular groove;

[0045] - the orifice(s) of the bridge(s) communicate(s) with the annular groove;

[0046] - the middle part of each of the lights has an axial width or dimension that is less than a circumferential width or dimension of each of the lateral parts of that light;

[0047] - each of the bridges has a general T-shape due to the lateral parts of the lights, and includes a part of greater circumferential width located on the side of the second disc, and a part of lesser circumferential width located on the side of the first disc;

[0048] - the narrower part of each of the bridges has a circumferential width or dimension which represents at least 1 / 3 of a circumferential width or dimension of the wider part;

[0049] -- each of the bridges includes, on the side of the first disc, a V-shaped notch;

[0050] -- said V-shaped notch is formed in the part with the smallest circumferential width of each of the bridges;

[0051] -- the cage carrier includes external splines for coupling to another shaft.

[0052] The present invention also relates to an aircraft turbomachine comprising a reducer as described above.

[0053] Brief description of the figures

[0054] 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:

[0055] [Fig.1] Figure 1 is a schematic axial cross-sectional view of a turbomachine using the invention;

[0056] [Fig.2] Figure 2 is a schematic axial cross-sectional view of a mechanical reducer;

[0057] [Fig.3] Figure 3 is a perspective view of a cage and cage-carrier assembly forming a mechanical reducer planet carrier;

[0058] [Fig.4] Figure 4 is an axial and partial cross-sectional view of part of the satellite carrier of Figure 3;

[0059] [Fig.5] Figure 5 is a detail view of Figure 4;

[0060] [Fig.6] Figure 6 is a schematic front view of the satellite carrier of Figure 3; [Fig.7] Figure 7 is a schematic perspective view of a satellite carrier for a reducer according to a first embodiment of the invention;

[0061] [Fig.8] Figure 8 is a larger scale view of part of the satellite carrier of Figure 7 and shows a light and an opening of the satellite carrier cage;

[0062] [Fig.9] Figure 9 is a schematic perspective view of the satellite carrier cage of Figure 7;

[0063] [Fig.10] Figure 10 is a larger scale view of part of Figure 9;

[0064] [Fig. 11] Figure 11 is a schematic perspective view of an alternative embodiment of the invention and shows a detail similar to that of Figure 10;

[0065] [Fig.12] Figure 12 is a schematic perspective and axial section view of the variant of Figure 11;

[0066] [Fig.13] Figure 13 is another schematic perspective and cross-sectional view of the variant of Figure 11;

[0067] [Fig.14] Figure 14 shows in a very schematic way several variants of the realization of the lateral parts of the lights;

[0068] [Fig.15] Figure 15 is a schematic perspective view of another variant embodiment of the invention and shows a detail similar to that of Figure 10;

[0069] [Fig. 16] Figure 16 is a schematic perspective view of another embodiment of the invention and shows a detail similar to that of Figure 10; and

[0070] [Fig.17] Figure 17 is a schematic perspective view of another variant embodiment of the invention and shows a detail similar to that of Figure 10.

[0071] Detailed description of the invention Figure 1 describes 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.

[0072] The blower S is driven by a blower shaft 4 which is connected to the BP shaft 3 by means of a mechanical reducer 10. This reducer 10 is generally of the planetary or epicyclic type.

[0073] Although the following description relates to a planetary or epicycloidal type reducer, it also applies to a mechanical differential in which its three essential components, namely the planet carrier, the ring and the sun gear, are mobile in rotation, the rotational speed of one of these components depending in particular on the difference in speeds of the other two components.

[0074] The gearbox 10 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 10. 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.

[0075] Figure 1 shows part of a gearbox 10, which can take different forms depending on whether certain parts are fixed or rotating. At the input, the gearbox 10 is connected to the shaft BP 3, for example, via splines 7. Thus, the shaft BP 3 drives a planetary gear called the sun gear 11. Typically, the sun gear 11, whose axis of rotation coincides with the X-axis of the turbomachine 1, drives a series of gears called sun gears 12, which are equally spaced circumferentially on the same diameter around the X-axis of rotation. This diameter is equal to twice the operating center distance between the sun gear 11 and the sun gears 12. The number of sun gears 12 is generally defined as between three and seven for this type of application.

[0076] The set of satellites 12 is held by a frame called the satellite carrier 12. Each satellite 12 rotates around its own Y axis, and meshes with the ring 14.

[0077] At the output of the gearbox 10, we have: In an epicyclic configuration, the set of planet gears 12 drives the planet carrier 13 in rotation around the X-axis of the turbomachine. The ring gear 14 is fixed to the motor or stator housing 5 via a ring carrier 15, and the planet carrier 12 is fixed to the fan shaft 4. In a planetary configuration, the set of planet gears 12 is held by a planet carrier 12, which is fixed to the motor or stator housing 5. Each planet gear drives the ring gear, which is connected to the fan shaft 4 via a ring carrier 15.

[0078] Each satellite 12 is mounted to rotate freely around a Y-axis using a bearing 8. The Y-axis rotations of the satellites 12 are distributed around and parallel to the X-axis. The bearings 8 are, for example, of the roller bearing or hydrodynamic bearing type. Each bearing 8 is mounted on a physical axis 13a of the satellite carrier 12, and all these physical axes 13a are positioned relative to each other using one or more structural frames of the satellite carrier 12. There is a number of physical axes 13a and bearings 8 equal to the number of satellites 12. For operational, assembly, manufacturing, inspection, repair, or replacement purposes, the axes 13a and the frame may be separated into several parts.

[0079] For the same reasons mentioned previously, the teeth of a reduction gear can be separated into several helices. In our example, we detail the operation of a multi-helix reduction gear 10 with a ring gear divided into two half-rings: A front half-ring 14a consisting of a rim 14aa and a mounting flange half 14ab. The front helix of the reduction gear teeth is located on the rim 14aa. This front helix meshes with that of the satellite gear 12, which meshes with that of the solar gear 11. A rear half-ring 14b consisting of a rim 14ba and a mounting flange half 14bb. The rear helix of the reduction gear teeth is located on the rim 14ba. This rear helix meshes with that of the satellite gear 12, which meshes with that of the solar gear 11.

[0080] The front sprocket 14a mounting bracket half-flange 14ab and the rear sprocket 14b mounting bracket half-flange form the sprocket mounting bracket 14c. The sprocket 14 is attached to the sprocket carrier 15 by joining the sprocket mounting bracket 14c and the sprocket carrier mounting bracket 15a using, for example, a bolted assembly. In the following, a half-flange may be referred to as a flange.

[0081] The arrows in Figure 1 describe the oil flow within the gearbox 10. The oil enters the gearbox 10 from the stator section 5 into the distributor 16 by various means, which will not be detailed in this view as they are specific to one or more types of architecture. The distributor 16 is divided into two parts, each generally repeated with the same number of planetary gears. The injectors 17a lubricate the gear teeth, and the arms 17b lubricate the bearings 8. The oil is supplied to the injector 17a and exits through the end 17c to lubricate the gear teeth. The oil is also supplied to each arm 17b and flows through the supply mouth 17d of the bearing 8. The oil then flows through the shaft 13a into one or more buffer zones 13b and then out through ports 13c to lubricate the bearings 8 of the satellites.

[0082] The satellite carrier 13 in Figure 2 is formed from a single piece in the example shown. In Figures 3 to 5, the elements already described above are designated by the same reference numerals plus one hundred.

[0083] Figures 3 to 5 represent a particular satellite carrier technology 113, this satellite carrier comprising a cage 120 and a cage carrier 122 connected by ball joints.

[0084] The cage 120 comprises two radial annular discs or walls 136, 138 which are parallel to each other and perpendicular to the X axis, as well as a cylindrical wall 140 which extends between the external peripheries of these discs walls 136, 138.

[0085] The cylindrical wall 140 is of the double-skinned type and comprises an outer skin 140a interrupted by openings 143 and an inner skin 140b interrupted by the same openings 143. The outer skin 140a, separated by five openings 143, forms five outer brackets, and the inner skin 140b, separated by five openings 143, forms five inner brackets. Each pair of lower and upper brackets forms a clevis to receive the finger 182 of the cage holder 122. In other words, the brackets of each pair define a recess 180 for receiving a finger 182 of the cage holder 122. The brackets provide the structural connection between the walls 136 and 138. Oblong openings 180a are made in at least one of the walls 136 and 138 to allow the finger 182 to pass between the inner and outer brackets. These 180a lights open into the 180 housing units.

[0086] The cage 120 thus comprises an annular row of housings 180. These housings 180 receive the axial fingers 182 which are integral with an annular wall 182a substantially radial to the cage holder 122. The wall 182a is located at an axial end of the cage holder 122. The fingers 182 extend axially from the wall 182a and are engaged by axial translation in the housings 180.

[0087] Each finger 182 includes, substantially in its middle, a mounting ring 184 for the ball joint 186, designed to be traversed by a cylindrical pin 188 carried by the cage 120. The ring 184 has a substantially radial orientation with respect to the X-axis. It has a generally cylindrical shape. The cage 120 and the ball joint 186 have a thickness, measured in a radial direction with respect to the X-axis, that is less than the inter-bridge distance or the radial thickness of the oblong slot 180a, so that they can be engaged in this housing concurrently with the finger 182 supporting these parts.

[0088] Each housing 180 is traversed by a pin 188 which has a substantially radial orientation with respect to the X-axis. Each pin 188 comprises a cylindrical body 188a connected at an axial end, here radially internal, to an external annular collar 188b. The pin 188 is engaged by radial translation from the inside through radial holes in the bridges, its collar 188b being designed to bear radially against a flat face 191 of the outer bridge of the cage 120. After insertion of the pin 188 into the holes in the bridges, until the collar 188b bears against the outer bridge, the collar 188b is fixed to this bridge, for example by screwing.

[0089] Figure 6 shows a detail of the disks or walls 136, 138 of the planet carrier 113. In these figures, it can be seen that each of the walls 136, 138 includes first orifices 192, 194 centered respectively on the Y axes of rotation of the planets of the gearbox. In the example shown, there are five orifices 192, 194 on each of the walls 136, 138.

[0090] The invention proposes an improvement for a mechanical gearbox for an aircraft turbomachine.

[0091] As in the examples described above, the mechanical reducer 10 according to the invention comprises:

[0092] - a solar 11 centered on a central axis X,

[0093] - a ring 14 centered on the central axis X and extending around the solar element - satellites 12 guided in rotation by bearings 8 centered on bearing axes Y which are parallel to the central axis X, the satellites 12 being meshed with the solar element 11 and the ring 14, and

[0094] - a satellite carrier.

[0095] The satellite carrier is of the monobloc type as illustrated in Figure 2. The preceding descriptions in relation to Figure 2 may be used to illustrate and describe the invention. Figures 2 through 6 may also be used to illustrate and describe the invention insofar as they are not inconsistent with the following.

[0096] Figures 7 to 10 illustrate a first embodiment of a satellite carrier 213 according to the invention.

[0097] The satellite carrier 213 includes a cage 220 formed from a single piece in which the solar array and the satellites and their bearings are intended to be mounted.

[0098] The cage 220 is formed in one piece with a cage holder 222 which has a tree gate shape and may include external grooves for coupling to another tree.

[0099] Cage 220 includes:

[0100] - a first disk 236 centered on the X axis, called the first axis or central axis, and extending perpendicularly to this X axis, this first disk 236 having first bearing orifices 292 centered respectively on the Y axes, called bearing axes or second axes, which are parallel to the X axis and arranged around this X axis,

[0101] - a second disk 238 centered on the X axis and parallel and at a distance from the disk 236, this second disk 238 having second bearing ports 294 which are respectively centered on the Y axes, and

[0102] - bridges 296 extending between and connecting the discs 236 and 238, these bridges 296 being formed as a single piece with the discs 236 and 238, and the bridges being circumferentially separated from each other by openings 243 intended for the passage of the planet gears for their engagement with the ring gear. The first disc 236 is, for example, a front or upstream disc, and the second disc 238 is, for example, a rear or downstream disc, with reference to the position of the gearbox in the turbomachine and the gas flow within the turbomachine.

[0103] The first disk 236 is preferably the disk connected to the cage holder 222.

[0104] Ports 292, 294 are used to mount the satellites and in particular the satellite guidance bearings, in the satellite carrier 213. The bearings have longitudinal ends which are intended to be housed in these ports 292, 294. The bearings are plain (hydrodynamic) or rolling bearings for example.

[0105] The peculiarity of the cage 220 of figures 7 and 8 is that it has around the central axis X an annular row of lights 300 which are formed at least in part in one of the disks, such as the first disk 236 for example, and which extend in a radial direction.

[0106] The lights 300 extend radially from the outer periphery of the cage 220 where they open radially outwards axially next to the openings 243, to the inner periphery of the cage 220.

[0107] The drawings show that the opening of each of the lights 300 at the outer periphery of the cage 220 has a general U-shape (figures 7 to 9).

[0108] This U-shaped form includes a central and straight part 300a formed in the first disk 236 and extending in a plane Q1 perpendicular to the central axis X, and two lateral parts 300b, 300c formed respectively in two adjacent bridges 296.

[0109] The lateral parts 300b, 300c of each of the lights 300 open onto the inner periphery of the bridges 296.

[0110] Each of the bridges 296 may include on its inner periphery a single orifice 297 into which the inner peripheries of the lateral portions 300a, 300c of two adjacent lumens 300 open. This opening may have a general O-shape, as shown in Figures 9 and 10. The lateral portions 300b, 300c are preferably perpendicular to the median portion 300a and extend respectively in two planes Q2, Q3 passing through the central axis X.

[0111] The central part 300a preferably has a width L1 or axial dimension, in particular maximum, which is less than a width L2 or circumferential dimension, in particular maximum, of each of the lateral parts 300b, 300c. The width L1 is measured in the axial direction while the width L2 is measured in the circumferential direction with respect to the central axis X.

[0112] L2 can be defined by the radius of curvature at the end of the lateral parts 300b, 300c opposite the median part 300a.

[0113] The middle part 300a may have a circumferential length that is greater than the circumferential dimension of an opening 243.

[0114] Figures 7 and 9 show that each of the bridges 296 can have a general T-shape due to the lateral parts 300b, 300c of the openings 300. Each of the bridges 296 comprises a part 296a of greater circumferential width located on the side of the second disk 238, and a part 296b of lesser circumferential width located on the side of the first disk 236.

[0115] The narrower portion 296b of each of the 296 bridges has a width L3, or circumferential dimension, that is at least 1 / 3 of a width L4, or circumferential dimension, of the wider portion. Widths L3 and L4 are measured circumferentially with respect to the central axis X.

[0116] Each of the bridges 296 may include, on the side of the first disc 236, a V-shaped notch 298. This notch 298 is formed in the portion 296b with the smallest circumferential width of each of the bridges 296. Each notch 298 preferably has a symmetrical shape with respect to a plane passing through the central axis X and the middle of the bridge 296. Each notch 298 flares axially on the side opposite the second disc 238. Figures 11 to 13 show an alternative embodiment of the invention which differs from the previous embodiment essentially in two aspects.

[0117] According to a first aspect, the cage 220 includes on its inner periphery an annular groove 400 which extends around the central axis X and opens radially inwards. This annular groove 400 is preferably in communication with the slots 300 and in particular with their medial parts 300a (see passage 400a figure 12).

[0118] The annular groove 400 preferably has an external diameter Dext which is greater than the smallest diameter Dminl of a circumference C1 centered on the central axis X and passing through the first orifices 292 of the first disk 236. The diameter Dext is preferably less than the largest diameter Dmaxl of a circumference C2 centered on the central axis X and passing through these first orifices 292.

[0119] The annular groove 400 has an external diameter Dext which is greater than an internal diameter Dmin2 of the lumen 300.

[0120] The annular groove 400 has an internal diameter Dint which is less than the smallest diameter Dminl of the circumference C1.

[0121] According to a second aspect, each of the bridges 296 includes on its internal periphery two orifices 297a, 297b formed by the outlets of two lateral parts 300b, 300c of two adjacent lights 300.

[0122] The two orifices 297a, 297b of each of the bridges 296 are symmetrical with respect to a plane Q4 passing through the central axis X and the middle of the corresponding bridge 296.

[0123] The two openings 297a, 297b of each of the bridges 296 are each bean-shaped and / or elongated along the central axis. The openings 297a, 297b of the bridges 296 are preferably at an axial distance from the annular groove 400 and / or at a circumferential distance from this annular groove 400.

[0124] In the examples shown in Figures 7 to 13, which are not exhaustive, the second bearing holes 294 of the second disk 238 have diameters D1 larger than those D2 of the first bearing holes 292 (Figures 12 and 13, for example). This is because the second bearing holes 294 can accommodate mounting covers for the second longitudinal ends of the bearings. These second longitudinal ends are engaged in holes in the covers, which are themselves engaged in the second bearing holes 294 of the second disk 238. The holes in the covers can have a diameter equal to the diameter D2 of the first bearing holes 292.

[0125] In general, the 300 slots allow for more flexible connections between the cage and the satellites, particularly the satellite guide bearings. The bridges 296, and especially their narrower sections 296b, transmit the operating forces, particularly the loads from the gear teeth meshing in the gearbox. Furthermore, as shown in the examples in Figures 7 to 13, the first disc 236 of the cage 220 maintains a continuous annular section Z extending radially over 360° inside the first mounting holes 292 for the satellite bearings. This is useful for maintaining a certain rigidity of the cage in this area (Figures 7, 11, and 12, for example).

[0126] Figure 14 shows different possible shapes for the lateral parts 300b, 300c of each light 300. It can be seen that the radii of curvature at the ends of these parts 300b, 300c, opposite the median part 300a, are similar, these radii of curvature being optimized to avoid stress concentrations in these areas.

[0127] Figures 15 to 17 show variant embodiments of the 296 bridges and in particular of their radially internal ends or internal peripheries.

[0128] In Figure 15, it can be seen that the two lateral parts 300b, 300c of two adjacent lumens 300 join to open onto the inner periphery of each of the bridges 296, forming a single orifice 297. In Figure 16, it can be seen that each of the bridges 296 includes on its two sides respectively two orifices 299a, 299b formed by openings of two lateral parts 300b, 300c of two adjacent lumens 300. In Figure 17, it can also be seen that each of the bridges 296 includes on its inner periphery a single orifice 297 which opens into the annular groove 400.

Claims

DEMANDS 1. Mechanical gearbox (10) for an aircraft turbomachine (1), this gearbox comprising: - a solar (11) centered on a central axis (X), - a corona (14) centered on the central axis (X) and extending around the solar (11), - satellites (12) guided in rotation by bearings (8) centered on bearing axes (Y) which are parallel to the central axis (X), the satellites (12) being meshed with the solar element (11) and the corona (14), and - a satellite carrier (213) comprising a cage (220) in which the solar array (11) and the satellites (12) and their bearings (8) are mounted, the cage (220) being formed in one piece with a cage support (222) which has a portion-of-a-tree shape and the cage (220) comprising: - a first disk (236) centered on the central axis (X) and extending perpendicularly to this central axis (X), this first disk (236) having first bearing orifices (292) centered respectively on the bearing axes (Y) and which receive first longitudinal ends (8a) of the bearings (8), - a second disk (238) centered on the central axis (X) and extending parallel and axially at a distance from the first disk (236), this second disk (238) having second bearing ports (294) which are respectively centered on the bearing axes (Y) and which receive second longitudinal ends (8b) of the bearings (8), and - bridges (296) extending between the first and second discs (236) and connecting them, the bridges (296) being circumferentially separated from each other by openings (243) through which the satellites (12) pass for their engagement with the ring (14), characterized in that the cage (220) comprises around the central axis (X) an annular row of lights (300) extending radially from the outer periphery of the cage (220) to the inner periphery of the cage (220), the outlet of each of the lights (300) at the outer periphery of the cage (220) having a general U-shape and comprising a median (300a) and straight part formed in the first disk (236) and extending axially next to one of the openings (243) in a plane (Q1) perpendicular to the central axis (X), and two lateral parts (300b, 300c) formed respectively in two adjacent bridges (296).

2. Reducer (10) according to claim 1, in which the lateral parts (300b, 300c) of each of the lights (300) are perpendicular to the middle part (300a) of this light (300) and extend respectively in two planes (Q2, Q3) passing through the central axis (X).

3. Reducer (10) according to claim 1 or 2, in which the cage (220) includes at its inner periphery an annular groove (400) which extends around the central axis (X) and which opens radially inwards, this annular groove (400) being in communication with the lights (300) and in particular with their middle parts (300a).

4. Reducer (10) according to claim 3, wherein the annular groove (400) has an external diameter (Dext) which is greater than the smallest diameter (Dminl) of a circumference (C1) centered on the central axis (X) and passing through the first orifices (292) of the first disk (236), and which is preferably less than the largest diameter (Dmaxl) of a circumference (C2) centered on the central axis (X) and passing through the first orifices (292) of the first disk (236).

5. Reducer (10) according to claim 3, wherein the annular groove (400) has an external diameter (Dext) which is greater than an internal diameter (Dmin2) of the slots (300).

6. Reducer (10) according to any one of claims 3 to 5, wherein the annular groove (400) has an internal diameter (Dint) which is less than the smallest diameter (Dminl) of a circumference (C1) centered on the central axis (X) and passing through the first orifices (292) of the first disk (236).

7. Reducer (10) according to any one of the preceding claims, in which the lateral parts (300b, 300c) of each of the lights (300) open onto the inner periphery of the bridges (296).

8. Reducer (10) according to claim 7, in which each of the bridges (296) comprises on its two sides respectively two orifices (299a, 299b) formed by outlets of two lateral parts (300b, 300c) of two adjacent lights (300).

9. Reducer (10) according to claim 7, in which each of the bridges (296) comprises at its inner periphery a single orifice (297) formed by outlets of two lateral parts (300b, 300c) of two adjacent lights (300).

10. Reducer (10) according to claim 7, in which each of the bridges (296) comprises at its inner periphery two orifices (297a, 297b) formed by outlets of two lateral parts (300b, 300c) of two adjacent lights (300).

11. Reducer (10) according to claim 10, wherein the two orifices (297a, 297b) of each of the bridges (296) are symmetric with respect to a plane (Q4) passing through the central axis (X) and the middle of the corresponding bridge (296).

12. Reducer (10) according to claim 10 or 11, in which the two orifices (297a, 297b) of each of the bridges (296) each have a bean-shaped, i.e. curved, and / or each have an elongated shape along the central axis (X).

13. Reducer (10) according to any one of claims 9 to 12, depending on any one of claims 3 to 6, wherein the orifice(s) (297a, 297b) of the bridges (296) is / are at an axial distance from the annular groove (400) and / or is / are at a circumferential distance from the annular groove (400).

14. Reducer (10) according to any one of claims 9 to 12, depending on any one of claims 3 to 7, wherein the orifice(s) (297a, 297b) of the bridges (296) communicate(s) with the annular groove (400).

15. Reducer (10) according to any one of the preceding claims, wherein the middle part (300a) of each of the lights (300) has a width (L1) or axial dimension which is less than a width (L2) or circumferential dimension of each of the lateral parts (300b, 300c) of this light (300).

16. Reducer (10) according to any one of the preceding claims, wherein each of the bridges (296) has a general T-shape due to the lateral parts (300b, 300c) of the slots (300), and comprises a circumferential part (296a) of greater width (L3) located on the side of the second disc (238), and a circumferential part (296b) of lesser width (L4) located on the side of the first disc (236).

17. Reducer (10) according to claim 16, wherein the smaller width part (296b) of each of the bridges (296) has a width (L4) or circumferential dimension which represents at least 1 / 3 of a width (L3) or circumferential dimension of the larger width part (296b).

18. Turbomachine (1), in particular for aircraft, comprising a reduction gear (10) according to any one of the preceding claims.

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