Module for an aircraft turbine engine

Abstract

A module (20) for an aircraft turbine engine (1), comprising a shaft (22) and a reduction sun gear (24), the shaft (22) having first splines (26), the sun gear (24) having an external toothset (28) and second splines (30) coupled with the first splines (26) of the shaft (22), characterized in that: - the toothset (28) comprises a first midplane (H1) which is perpendicular to the axis (X) and which passes through the middle of the toothset (28), - the splines (26, 30) comprise at least one second midplane (H2) which is perpendicular to the axis (X) and which passes through the middle of the splines (30, 26), the or each second plane (H2) being axially spaced from the first plane (H1), and in that the sun gear (24) comprises at least one stiffener (32) at the splines (26, 30).

Description

[0001] DESCRIPTION

[0002] TITLE: MODULE FOR AN AIRCRAFT TURBOMACHINE

[0003] Technical field of the invention

[0004] The present invention relates to the field of aircraft turbomachines as well as mechanical reducers for such turbomachines.

[0005] Technical background

[0006] The state of the art includes in particular documents W0-A1 -2010 / 092263, FR-A1-2 987 416, FR-A1 -3 008 462, FR-A1-3 008 462, FR-A1-3 041 054, US-A1 -2023 / 340912 and US-A1 -2022 / 042460.

[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] 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 longitudinal axis X of the turbomachine. The planet gears each have a different axis of revolution and are equally distributed over the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis X.

[0010] There are several gearbox architectures. In the state of the art of double-flow turbomachinery, gearboxes are of the planetary or epicyclic type. In other similar applications, there are so-called differential or "compound" architectures.

[0011] - On a planetary reducer, the planet carrier is fixed and the crown is integral with the output shaft of the device which rotates in the opposite direction to the solar.

[0012] - On an epicyclic reducer, the crown is fixed and the planet carrier is integral with the output shaft of the device which rotates in the same direction as the solar.

[0013] - On a differential reducer, no element is fixed in rotation. The crown rotates in the opposite direction to the sun and the planet carrier.

[0014] 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.

[0015] There are several types of contact meshing such as straight, helical or herringbone teeth.

[0016] The gear teeth absorb the forces passing through the reducer. These loads locally create deformations which are taken into account in the sizing of each component of the reducer.

[0017] In particular, the loads on the gear teeth of the sun gear tend to deform the gear section depending on the number of satellites and the torque passing through the satellites. For example, in the case of a three-satellite reducer, the sun gear becomes trilobed under the effect of the load it is subjected to (see figure 3).

[0018] Such deformations can in some cases limit the solutions for securing the solar with the shaft intended to transmit power to it. In particular, spline-type solutions, highly prized for their compactness and ease of implementation and assembly, can be made impossible by these deformations, when there are also strong integration constraints (minimum internal diameter of the solar and maximum external diameter of the reducer), the fatigue life cannot be guaranteed in the event of high stresses. The deformations induced under and around the solar therefore prove to be limiting with respect to existing coupling solutions if one wishes to implement them near the solar. The invention proposes a solution to this problem, which is simple, effective and economical.

[0019] Summary of the invention

[0020] The invention relates to a module for an aircraft turbomachine, this module comprising a shaft and a reduction gear sun gear, the shaft having a generally elongated and tubular shape along an axis and comprising first splines, the sun gear having an annular shape and extending around the axis and the shaft, the sun gear comprising external teeth as well as second splines coupled with the first splines of the shaft, characterized in that:

[0021] - the teeth include a first median plane which is perpendicular to the axis and which passes through the middle of the teeth,

[0022] - the second grooves comprise at least one second median plane which is perpendicular to the axis and which passes through the middle of the grooves, the or each second plane being axially spaced from the first plane,

[0023] - the first grooves are crossed by said at least one second plane which passes through the middle of these grooves, and in that the solar comprises at least one stiffener at right angles to and / or near the grooves.

[0024] The invention thus proposes to solve the problem of the prior art on the one hand by an axial offset of the teeth with respect to the splines of the solar, and on the other hand by a stiffening of the solar at the level of its splines. This has the consequence that the forces passing through the splines between the shaft and the solar are axially offset with respect to the teeth. Furthermore, the stiffening of the solar at the level of the splines makes it possible to transmit the torque forces without deformation or with a limited deformation of the solar. The module 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:

[0025] -- the first splines are external splines and the second splines are internal splines; alternatively, the first splines are internal splines and the second splines are external splines;

[0026] - the toothing and the grooves of the solar overlap each other in the axial direction;

[0027] - the teeth are located on a first axial section of the sun and the splines of the sun are located outside this first section and coupled with the splines of the shaft which are axially spaced from this section;

[0028] - the splines of the solar are located only on a second section which is adjacent to the first section, and the splines of the shaft are located on a single section of the shaft which is axially spaced from the first section of the solar;

[0029] - the solar splines are located at a free end of the solar, and the shaft splines are located at a free end of the shaft;

[0030] - the splines of the solar are located on second and third sections which are separated from each other by the first section, and the splines of the shaft are located on two sections of the shaft which are axially spaced from each other and from the first section of the solar;

[0031] - the grooves of the second section differ from the grooves of the third section by at least one parameter chosen from the length of the grooves, the circumferential position of the grooves around the axis, and the angle of the grooves;

[0032] - the second section or each of the second and third sections is associated with at least one stiffener or a pair of stiffeners; - the second section or each of the second and third sections is connected to the first section by an elastically deformable intermediate section and in particular having a thinner thickness than the rest of the solar;

[0033] - the or each stiffener is formed by a radially external annular rib or by a radially external annular boss;

[0034] -- the annular boss has any shape, for example rounded, convex or T-shaped;

[0035] - a nut is screwed onto a thread of the shaft and rests axially on one end of the solar;

[0036] - the toothing of the solar has a length which is at least twice greater than a length of the splines of the solar or a cumulative length of the splines of the solar;

[0037] - the or each stiffener has an external diameter which is equal to the external diameter of the teeth to within + / -20%;

[0038] - the or each stiffener located near the grooves is located at an axial distance from these grooves less than a length of these grooves;

[0039] - the solar is stepped and comprises at least two sections of different internal diameters, the section of smaller diameter comprising the teeth and the section of larger diameter comprising the grooves, the stiffener located near the grooves being formed by a connecting zone between these two sections;

[0040] -- the shaft has an internal diameter between 30 mm and 500 mm;

[0041] -- the grooves or the or each section comprising grooves (of the solar, or of the shaft respectively) has a length of between 5 and 100 mm;

[0042] -- the number of grooves or sections comprising grooves (of the solar, or of the shaft respectively) is between 1 and 5;

[0043] -- the distance between the splines and the teeth is between -100 mm (in the case of partial overlap) and 300 mm; -- the number of stiffeners per spline or section of splines (of the solar, or of the shaft respectively) is between 1 and 30;

[0044] -- the distance separating the or each stiffener from the teeth is between 0 (stiffener attached to the teeth) and 300 mm;

[0045] -- the number of elastically deformable intermediate sections is between 1 and 5;

[0046] -- the or each elastically deformable section comprises a bellows or at least one corrugation;

[0047] - the module of the splines (ratio of the circumferential pitch or circumferential distance between the teeth of the splines taken to the primitive diameter by the number n, also equal to the ratio of the primitive diameter by the number of teeth) is between 1 and 6 mm;

[0048] -- the angular offset between the grooves of the second and third sections is between 0.001° and 5°, and preferably between 0.1° and 1°;

[0049] -- the ratio between the length of the grooves of one section and the length of the grooves of another section is between 2 and 20 between the smallest and the largest;

[0050] -- the splines have an angle of inclination relative to the axis of the shaft, which is between 0.001° and 5°, and preferably between 0.1° and 1°;

[0051] -- the or each stiffener (or at least some of the stiffeners) is / are crossed by a median plane or one of the median planes of the grooves;

[0052] -- the or each stiffener (or at least some of the stiffeners) is / are spaced from the median plane(s) of the grooves.

[0053] The invention further relates to a turbomachine, in particular for an aircraft, comprising a module as described above, the turbomachine comprising a reduction gear comprising the sun gear of the module as well as a crown with internal teeth and satellites meshed with the teeth of the sun gear and the teeth of the crown gear.

[0054] Brief description of the figures 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:

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

[0056] [Fig.2] Figure 2 is a partial axial sectional view of a mechanical reducer,

[0057] [Fig.3] Figure 3 is a schematic perspective view of a solar reducer,

[0058] [Fig.4] Figure 4 is a schematic axial sectional view of a module according to a first embodiment of the invention, this module comprising a shaft and a reduction gear,

[0059] [Fig.5a-5b] Figures 5a and 5b are schematic views of a shaft for a module according to the invention, Figure 5a being a partial perspective view of this shaft, and Figure 5b being a side view of this shaft, [Fig.6] Figure 6 is a partial schematic perspective view of an alternative embodiment of the shaft,

[0060] [Fig.7] Figure 7 is a partial schematic perspective view of another alternative embodiment of the shaft,

[0061] [Fig.8] Figure 8 is a partial schematic view in axial section of an alternative embodiment of a module according to the invention,

[0062] [Fig.9] Figure 9 is a partial schematic view in axial section of another alternative embodiment of a module according to the invention,

[0063] [Fig.10] Figure 10 is a partial schematic view in axial section of an alternative embodiment of a module according to the invention,

[0064] [Fig. 11] Figure 11 is a partial schematic view in axial section of another alternative embodiment of a module according to the invention;

[0065] [Fig.12] Figure 12 is a partial schematic view in axial section of another alternative embodiment of a module according to the invention;

[0066] [Fig.13] Figure 13 is a partial schematic view in axial section of another alternative embodiment of a module according to the invention; [Fig.14] Figure 14 is a partial schematic view in axial section of another alternative embodiment of a module according to the invention;

[0067] [Fig.15] Figure 15 is a partial schematic view in axial section of another alternative embodiment of a module according to the invention;

[0068] [Fig.16] Figure 16 is a partial schematic view in axial section of another alternative embodiment of a module according to the invention.

[0069] Detailed description of the invention

[0070] 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.

[0071] The blower S is driven by a blower shaft 4 which is driven by the LP shaft 3 by means of a reducer 6. This reducer 6 is generally of the planetary or epicyclic type.

[0072] The following description concerns an epicyclic type reducer, the planet carrier and the sun gear of which are mobile in rotation, the crown of the reducer being fixed in the motor reference frame.

[0073] 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. Figure 2 shows an epicyclic reducer 6. At the input, the reducer 6 is connected to the LP shaft 3, for example by means of internal splines 7a. Thus, the BP 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 equally distributed over the same diameter around the axis of rotation X.This diameter is equal to twice the operating center distance between the solar 7 and the satellites 8. The number of satellites 8 is generally defined between three and seven for this type of application.

[0074] Alternatively, the satellites 8 might not be equally distributed around the X axis.

[0075] The set of satellites 8 is held by a frame called a satellite carrier 10. Each satellite 8 rotates around its own Y axis, and meshes with the crown 9.

[0076] At the output we have:

[0077] ■ In this epicyclic configuration, the set of planet gears 8 drives the planet carrier 10 in rotation 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.

[0078] ■ In another planetary configuration, all of the planet gears 8 are held by a planet carrier 10 which is fixed to the engine casing or stator 5. Each planet gear 8 drives the crown which is attached to the fan shaft 4 via a crown carrier 12.

[0079] ■ In another differential configuration, all of the satellites 8 are held by a planet carrier 10 which is connected to a first fan shaft 5. Each satellite 8 drives the crown which is connected to a second counter-rotating fan shaft 4 via a crown carrier 12.

[0080] Each satellite 8 is mounted to rotate freely using a bearing 11, for example of the rolling bearing or hydrodynamic bearing type. Each bearing 11 is mounted on one of the physical axes 10b of the planet carrier 10 and all the axes are positioned relative to each other using one or more structural frames 10a of the planet carrier 10. There are a number of axes 10b and bearings 11 equal to the number of satellites. For reasons of operation, assembly, manufacturing, control, repair or replacement, the axes 10b and the frame 10a can be separated into several parts.

[0081] For the same reasons mentioned above, the teeth of a satellite can be separated into several helices or teeth, each having a median plane P, P'. In our example, we detail the operation of a reducer in which each satellite comprises two series of chevron teeth cooperating with a crown separated into two half-crowns:

[0082] ■ An upstream half-crown 9a consisting of a rim 9aa and a half-fixing flange 9ab. On the rim 9aa is the front propeller meshing with a propeller of the toothing 8d of each satellite 8. The propeller of the toothing 8d also meshes with that of the sun 7.

[0083] ■ A downstream half-crown 9b consisting of a rim 9ba and a half-fixing flange 9bb. On the rim 9ba is the rear propeller meshing with a propeller of the toothing 8d of each satellite 8. The propeller of the toothing 8d also meshes with that of the sun 7.

[0084] If the helix 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 teeth and on another median plane P' for the downstream teeth.

[0085] Figure 2 thus illustrates the case of a single-stage gear reducer 6, i.e. the same toothing 8d of each satellite 8 cooperates with both the sun gear 7 and the crown wheel 9. Even if the toothing 8d comprises two series of teeth, these teeth have the same average diameter and form a single toothing called a chevron.

[0086] 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.

[0087] 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 a distributor 13 by different means which will not be specified in this view because they are specific to one or more types of architecture. The distributor 13 comprises injectors 13a and arms 13b.

[0088] The injectors 13a have the function of lubricating the teeth and the arms 13b have the function of lubricating the bearings. The oil is brought to the injector 13a to exit through the end 13c in order to lubricate the teeth. The oil is also brought to the arm 13b and circulates via the supply mouth 13d of the bearing. The oil then circulates through the axis in one or more buffer zones 10c to then exit through the orifices 10d in order to lubricate the bearings of the satellites.

[0089] In the prior art shown in Figure 2, a reduction gear 7 extends around the axis X and comprises at its internal periphery the internal splines 7a for coupling with the shaft 3, and at its external periphery a toothing 7b for meshing with the toothing 8d of each satellite 8.

[0090] The toothing 7b comprises a first median plane H1 which is perpendicular to the X axis and which passes through the middle of the toothing 7b.

[0091] The internal grooves 7a comprise at least one second median plane H2 which is perpendicular to the X axis and which passes through the middle of the grooves 7a.

[0092] The shaft 3 comprises external splines 3a which are crossed by the second plane which passes through the middle of these splines 3a.

[0093] It can be seen that the planes H1 and H2 are the same, that is to say that the splines 3a, 7a and the teeth 7b are aligned in the radial direction.

[0094] To avoid or limit the phenomenon illustrated in Figure 3 and described above, the present invention proposes an improved module, comprising a shaft and a reduction gear, embodiments of which are illustrated in Figures 4 and following.

[0095] Figure 4 illustrates a first embodiment of a module 20 according to the invention.

[0096] Compactness, modularity, and disassembly time are key factors in aircraft engine design. There are several ways to connect modules together, and it is common to seek to optimize engine assembly and disassembly as much as possible. The presence of a mechanical gearbox in an aircraft engine adds a relatively massive assembly whose modularity can be difficult to ensure given other constraints such as dynamics or compactness. Various solutions already exist for assembling the solar element of a gearbox with its input shaft.

[0097] The module 20 according to the invention comprises a shaft 22 and a sun gear 24 for a reducer which can be a planetary or epicyclic reducer.

[0098] According to the invention, the connection between the shaft 22 and the solar 24 is made by coupling splines.

[0099] The shaft 22 has a generally elongated and tubular shape along an axis X and comprises external splines 26.

[0100] The solar 24 has an annular shape and extends around the X axis and the shaft 22.

[0101] The sun gear 24 comprises external teeth 28 as well as internal splines 30 coupled with the external splines 26 of the shaft 22.

[0102] The toothing 28 comprises a first median plane H1 which is perpendicular to the X axis and which passes through the middle of the toothing 28.

[0103] The internal grooves 30 comprise at least one second median plane H2 which is perpendicular to the X axis and which passes through the middle of the grooves 30.

[0104] The external grooves 26 are crossed by the or each second plane H2 which passes through the middle of these grooves 26. The particularity of the invention is linked to the fact that the or each second plane H2 is axially spaced from the first plane H1.

[0105] Another feature of the invention is linked to the fact that the solar 24 comprises at least one stiffener 32 at right angles to and / or near the grooves 26, 30.

[0106] In the first embodiment illustrated in Figure 4, the toothing 28 is located on a first axial section 24a of the sun gear 24 and the splines 30 of the sun gear 24 are located outside this first section 24a and coupled with the splines 26 of the shaft 22 which are axially spaced from this section 24a.

[0107] The splines 30 of the solar 24 are located on second and third sections 24b, 24c which are separated from each other by the first section 24a. The splines 26 of the shaft 22 are located on two sections 22a, 22b of the shaft 22 which are axially spaced from each other and from the first section 24a of the solar 24.

[0108] The splines 30 of the second and third sections 24b, 24c may be identical. The splines 26 of the two sections 22a, 22b of the shaft 22 may also be identical.

[0109] Each of the second and third sections 24b, 24c can be associated with at least one stiffener 32. In the example shown, each stiffener 32 is formed by a radially external annular rib.

[0110] The stiffeners 32 can be crossed by the H2 planes.

[0111] In the example shown, the toothing 28 of the sun 24 has a length L1 which is at least twice as long as a cumulative length L2+L3 of the splines 30 of the sun 24. The lengths L2 and L3 of the splines of the two sections 22a, 22b may be identical.

[0112] The or each stiffener 32 may have an external diameter D1 which is equal to the external diameter D2 of the teeth 28 to within + / -20%.

[0113] Figures 5a and 5b show an alternative embodiment of the shaft 22 which differs from the embodiment described with reference to Figure 4 in that the splines 26 of its two sections 22a, 22b are different. They differ here by their circumferential position around the axis X. The splines 26 of the section 22a have a first angular position with respect to the axis X and the splines 26 of the other section 22b have a different angular position with respect to the axis X. In other words, the splines 26 of the section 22a are not axially aligned with the splines 26 of the section 22b. The circumferential misalignment can be between 0.001 and 5° for example, and preferably between 0.1 and 1°.

[0114] It is understood that the grooves 30 of the solar 24 are complementary and therefore that the grooves 30 of the section 24a are not axially aligned with the grooves 30 of the section 24b.

[0115] Figure 6 shows an alternative embodiment of the shaft 22 which differs from the embodiment described with reference to Figure 4 in that the splines 26 of its two sections 22a, 22b are different. They differ here by their length L2, L3 along the axis X. The splines 26 of the section 22a have a length L2 and the splines 26 of the other section 22b have a length L3 different from the length L2 and in particular smaller than the length L2.

[0116] It is understood that the grooves 30 of the solar 24 are complementary and therefore that the grooves 30 of the section 24a have a length different from that of the grooves 30 of the section 24b.

[0117] Figure 7 shows an alternative embodiment of the shaft 22 which differs from the mode described with reference to Figure 4 in that the splines 26 of its two sections 22a, 22b are different. They differ here by their angle a1, a2 of inclination with respect to the axis X. The splines 26 of the section 22a have an angle of inclination a1 and the splines 26 of the other section 22b have an angle of inclination a2 which is different from the angle a1 and in particular greater than the angle a1. This angle can be between 0.001 and 5° for example, and preferably between 0.1 and 1°. It is understood that the splines 30 of the sun 24 are complementary and therefore that the splines 30 of the sections 24a, 24b have different angles of inclination.

[0118] The variant embodiments of the shaft 22 of figures 5a to 7 make it possible to optimize the input of the torque into the solar of the reducer.

[0119] Figure 8 shows an alternative embodiment of the module 20 which differs from the mode described with reference to Figure 4 in that the grooves 30 of the solar 24 are located only on a second section 24b which is adjacent to the first section 24a.

[0120] Furthermore, the splines 26 of the shaft 22 are located on a single section 22a of the shaft 22 which is axially spaced from the first section 24a of the sun 24.

[0121] The second section 24b is associated with at least one stiffener 32, which is here formed by a radially external annular rib.

[0122] The stiffener 32 can be crossed by the median plane H2 of the grooves 26, 30 or located just next to this plane.

[0123] The grooves 30 of the solar 24 are located at a free end of the solar 24.

[0124] The splines 26 of the shaft 22 are located at a free end of the shaft 22.

[0125] In the example shown, the free end of the shaft 22 comprises an external thread 34 for screwing a nut 36 which bears axially on the free end of the sun.

[0126] Figure 9 shows an alternative embodiment of the module 20 which differs from the embodiment described with reference to Figure 4 in that the splines 30 of the solar 24 are located only on a second section 24b which is adjacent to the first section 24a. Furthermore, the splines 26 of the shaft 22 are located on a single section 22a of the shaft 22 which is axially spaced from the first section 24a of the solar 24.

[0127] The second section 24b is associated with two stiffeners 32 (or a pair of stiffeners), which are here formed by two adjacent and radially external annular ribs. The stiffeners 32 and the ribs are here identical. One of the stiffeners 32 can be crossed by the median plane H2 of the grooves 26, 30 and the other of the stiffeners is then located at a distance from this plane H2.

[0128] The grooves 30 of the solar 24 are located at a free end of the solar 24.

[0129] The splines 26 of the shaft 22 are located at a free end of the shaft 22.

[0130] Figure 10 shows an alternative embodiment of the module 20 which differs from that described with reference to Figure 8 in that the second section 24b is associated with at least one stiffener 32, which is here formed by a radially external annular boss.

[0131] The stiffener is here crossed by the median plane H2 of the grooves 26, 30.

[0132] The boss here has a convex rounded shape in section, the convexity of which is oriented radially outwards.

[0133] Figure 11 shows an alternative embodiment of the module 20 which differs from that described with reference to Figure 9 in that the second section 24b is associated with a single stiffener 32, which is here formed by a radially external annular boss and by the fact that the second section 24b is connected to the first section 24a by an elastically deformable intermediate section 24c and having in particular a thinner thickness than the rest of the solar 24. This flexibility makes it possible to optimize the thermomechanical and dynamic behavior of the power transmission line. Alternatively, other forms of flexibility are conceivable, for example a bellows shape.

[0134] The stiffener 32 is here crossed by the median plane H2 of the grooves 26, 30.

[0135] Figure 12 shows an alternative embodiment of the module 20 which differs from that described with reference to Figure 11 in that the teeth 28 and the grooves 30 of the sun 24 overlap each other in the axial direction. The planes H1 and H2, however, remain spaced from each other.

[0136] The stiffener 32 is axially spaced from the median plane H2 of the grooves 26, 30.

[0137] Figure 13 illustrates another variant embodiment of the module 20 in which the solar 24 comprises external splines 30' and no longer internal splines 30. It is therefore understood that the shaft 22 comprises internal splines 26' for its coupling to the solar 24.

[0138] Furthermore, the solar 24 here comprises a stiffener 32 which is located next to its grooves 30'. As can be seen in the figure, the axial distance D between the stiffener 32 and the grooves 26', 30', is relatively small and preferably less than the length L2 of these grooves.

[0139] Figure 14 illustrates a particular form of stiffener 32 within the framework of the present invention, which here has a general T-shape in section.

[0140] Figure 15 illustrates another variant embodiment of the module 20 in which the solar 24 comprises external splines 30' and no longer internal splines 30 as in Figure 13. It is therefore understood that the shaft 22 comprises internal splines 26' for its coupling to the solar 24. Furthermore, the solar 24 here comprises two stiffeners 32, 32'. A first stiffener 32 similar to that of Figure 13 is located near the splines 30'.

[0141] The solar 24 is here stepped and comprises two sections 24d, 24e of different internal diameters. The section 24d of smaller diameter comprises the teeth 28 and the section 24e of larger diameter comprises the splines 30'.

[0142] The stiffener 32' is formed by the connecting zone between these two sections 24d, 24e.

[0143] Figure 16 illustrates another variant embodiment of the module 20 in which the solar 24 comprises external splines 30' and no longer internal splines 30 as in figure 13. It is therefore understood that the shaft 22 comprises internal splines 26' for its coupling to the solar 24. Furthermore, the solar 24 here comprises a stiffener 32' of the type of that of figure 15.

[0144] The solar 24 is here stepped and comprises two sections 24d, 24e of different internal diameters. The section 24d of smaller diameter comprises the teeth 28 and the section 24e of larger diameter comprises the splines 30'.

[0145] The stiffener 32' is formed by the connecting zone between these two sections 24d, 24e.

[0146] In yet another variant not shown, the shaft 22 could also comprise one or more stiffeners.

[0147] In general, with regard to all the embodiments and variants of the invention, the module may comprise one or more of the following characteristics: o the toothing of the solar has a length which is at least twice greater than a length of the splines of the solar or a cumulative length of the splines of the solar; o the or each stiffener has an external diameter which is equal to the external diameter of the toothing to within + / -20%; o the shaft has an internal diameter of between 30 mm and 500 mm; o the splines or the or each section comprising splines (of the solar, or of the shaft respectively) has a length of between 5 and 100 mm; o the number of splines or sections comprising splines (of the solar, or of the shaft respectively) is between 1 and 5; o the splines may be straight or curved; o the distance between the grooves and the teeth is between -100 mm (in the case of partial overlap) and 300 mm;o the number of stiffeners per spline or spline section (of the solar, or of the shaft respectively) is between 1 and 30; o the distance separating the or each stiffener from the teeth is between 0 (stiffener attached to the teeth) and 300 mm; o the number of elastically deformable intermediate sections is between 1 and 5; o the or each elastically deformable section comprises a bellows or at least one corrugation; o the modulus of the splines (circumferential pitch or circumferential distance between the teeth of the splines) is between 1 and 6 mm; o the angular offset between the splines of the second and third sections is between 0.001 ° and 5 °; o the ratio between a length of the splines of one section and a length of the splines of another section is between 2 to 20 between the smallest and the largest; o the splines have an angle of inclination relative to the shaft axis, which is between 0.001° and 5°.;

[0148] The invention allows the transmission of torque from a shaft to the solar of a reducer while preserving simple modularity and a healthy dynamic situation. This invention can be applied in any environment where a rotating machine with a reducer combines:

[0149] - a strong constraint of compactness;

[0150] - high transmitted powers; - a strong modularity constraint (need to assemble and disassemble easily).

Claims

CLAIMS 1. Module (20) for an aircraft turbomachine (1), this module (20) comprising a shaft (22) and a reduction gear sun gear (24), the shaft (22) having a generally elongated and tubular shape along an axis (X) and comprising first splines (26), the sun gear (24) having an annular shape and extending around the axis (X) and the shaft (22), the sun gear (24) comprising external teeth (28) as well as second splines (30) coupled with the first splines (26) of the shaft (22), characterized in that: - the toothing (28) comprises a first median plane (H1) which is perpendicular to the axis (X) and which passes through the middle of the toothing (28), - the second grooves (30) comprise at least one second median plane (H2) which is perpendicular to the axis (X) and which passes through the middle of the grooves (30), the or each second plane (H2) being axially spaced from the first plane (H1), - the first grooves (26) are crossed by said at least one second plane (H2) which passes through the middle of these grooves (26), and in that the solar (24) comprises at least one stiffener (32, 32') at the right angle of the grooves (26, 30).

2. Module (20) according to claim 1, wherein the teeth (28) and the grooves (30) of the sun (26) overlap each other in the axial direction.

3. Module (20) according to claim 1, in which the toothing (28) is located on a first axial section (24a) of the sun (24) and the splines (30) of the sun (24) are located outside this first section (24a) and coupled with the splines (26) of the shaft (22) which are axially spaced from this section (24a).

4. Module (20) according to claim 3, in which the splines (30) of the solar (24) are located only on a second section (24b) which is adjacent to the first section (24a), and the splines (26) of the shaft (22) are located on a single section (22a) of the shaft which is axially spaced from the first section (24a) of the solar (24).

5. Module (20) according to claim 4, wherein the splines (30) of the solar (26) are located at a free end of the solar (26), and the splines (26) of the shaft (22) are located at a free end of the shaft (22).

6. Module (20) according to claim 3, in which the splines (30) of the solar (26) are located on second and third sections (24b, 24c) which are separated from each other by the first section (24a), and the splines (26) of the shaft (22) are located on two sections (22a, 22b) of the shaft (22) which are axially spaced from each other and from the first section (24a) of the solar (24).

7. Module (20) according to claim 6, in which the grooves (30) of the second section (24b) differ from the grooves (30) of the third section (24c) by at least one parameter chosen from the length (L1, L2) of the grooves (30), the circumferential position of the grooves (30) around the axis (X), and the angle (a1, a2) of the grooves (30).

8. Module (20) according to one of claims 3 to 7, in which the second section (24b) or each of the second and third sections (24b, 24c) is associated with at least one stiffener (32) or a pair of stiffeners (32).

9. Module (20) according to one of claims 3 to 8, in which the second section (24b) or each of the second and third sections is connected to the first section (24a) by an intermediate section (24c) which is elastically deformable and in particular has a thinner thickness than the rest of the solar (24).

10. Module (20) according to one of the preceding claims, in which the or each stiffener (32) is formed by a radially external annular rib or by a radially external annular boss.

11. Module (20) according to one of the preceding claims, in which a nut (36) is screwed onto a thread (34) of the shaft (22) and bears axially on one end of the solar (24).

12. Module (20) according to one of the preceding claims, in which the toothing (28) of the solar (24) has a length (L1) which is at least twice as long as a length (L2) of the splines of the solar or a cumulative length (L2+L3) of the splines (30) of the solar (24).

13. Module (20) according to one of the preceding claims, in which the or each stiffener (32) has an external diameter (D1) which is equal to the external diameter (D2) of the teeth (28) to within + / -20%.

14. Module (20) according to one of the preceding claims, in which the solar (24) further comprises at least one stiffener (32) located near the grooves (26, 30) and in particular at an axial distance (D) from these grooves (26, 30) less than a length (L2) of these grooves (26, 30).

15. Module (20) according to one of the preceding claims, in which the solar (24) is stepped and comprises at least two sections (24d, 24e) of different internal diameters, the section (24d) of smaller diameter comprising the teeth (28) and the section (24e) of larger diameter comprising the grooves (30), the stiffener (32') of the grooves (26, 30) being formed by a connecting zone between these two sections (24d, 24e).

16. Aircraft turbomachine (1), comprising a module (20) according to one of the preceding claims, the turbomachine (1) comprising a reduction gear (6) comprising the sun gear (24) of the module (20) as well as a crown gear (9) with internal teeth and satellites (11) meshed with the teeth of the sun gear (24) and the teeth of the crown gear (9).

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