FR3153868A1 - SATELLITE CARRIER FOR A MECHANICAL REDUCER OF AN AIRCRAFT TURBOMACHINE - Google Patents

Abstract

Planet carrier (213) for a mechanical reduction gear (10) of an aircraft turbomachine (1), this planet carrier (213) comprising: - a first disc (236) comprising first orifices (292), - a second disc (238) comprising second orifices (294) aligned with the first orifices (292), the first and second discs (236, 238) comprising first annular faces (236a) facing each other, - bridges (296) which extend between the first and second discs (236, 238) and connect them together, the bridges (296) being formed in one piece with the first and second discs (236, 238), characterized in that at least one of said first faces (236a) comprises recesses (298) which are arranged next to said orifices (292, 294) and which are non-symmetrical. Figure for abstract: Figure 7

Description

SATELLITE CARRIER FOR A MECHANICAL REDUCER OF AN AIRCRAFT TURBOMACHINE Technical field of the invention

The present invention relates to a planet carrier for a mechanical reducer of an aircraft turbomachine, a reducer for a turbomachine comprising such a planet carrier as well as a turbomachine comprising such a reducer.

Technical approval plan

The state of the art includes in particular documents FR-A1-2 987 416, FR-A1-2 853 382, FR-A1-3 041 054, FR-A1-3 052 113, FR-A1-3 073 915, FR-A1-3 084 428.

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.

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.

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 of the turbomachine. 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 of the turbomachine.

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

- 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.

- 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.

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

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

The planet carrier may be in one piece or in the form of a cage and a cage carrier. The cage comprises an internal cavity in which the sun gear, the planet gears and the guide bearings for these planet gears are housed. The sun gear comprises internal splines for coupling to a first shaft of the turbomachine and the cage carrier comprises a cylindrical portion comprising external splines for coupling to another shaft.

The connection of the cage to the cage holder is generally rigid. Alternatively, a technology may be envisaged in which the cage is connected to the cage holder by “flexible” connections, such as described in document FR-A1-2 853 382. In such a case, the cage holder comprises an annular row of axial fingers which carry first connecting elements. These first connecting elements cooperate with second connecting elements mounted in housings of the cage to form the flexible connections between the cage holder and the cage, which allow at least one degree of freedom.

In operation, the planet carrier is subjected to forces that tend to deform it. This is the case for a single-piece planet carrier or a cage and cage carrier type. These deformations generate tilting of the planets, leading to degradation of the meshing, and risks of the appearance of an asymmetrical oil film in the case of the use of plain or hydrodynamic bearings for guiding the planets, or risks of generating tilting of the rollers in the case of the use of rolling bearings for guiding the planets.

These efforts and deformations must be rebalanced in order to limit or even cancel these effects.

The present invention provides a solution to this need, which is simple, effective and economical.

The invention relates to a cage for a planet carrier of a mechanical reducer of an aircraft turbomachine, this cage being formed from a single piece and comprising:

- a first disc centered on a central axis and extending radially and around with respect to this central axis, this first disc comprising first bearing orifices centered respectively on bearing axes which are distributed circumferentially around the central axis and parallel to this central axis,

- a second disc centered on the central axis and extending parallel and axially at a distance from the first disc, this second disc comprising second bearing orifices which are respectively centered on the bearing axes, the number of second bearing orifices being equal to the number of first bearing orifices,

the first and second discs comprising first annular faces axially facing each other,

- bridges which extend between the first and second discs and connect them together, the bridges being formed in one piece with the first and second discs,

characterized in that at least one of said first faces comprises a recess pattern arranged next to one of said bearing orifices, the recess pattern having a curved shape extending in an arc of a circle around the bearing orifice at which the recess pattern is located, and preferably the recess pattern preferably extending in a non-symmetrical manner relative to a radial plane passing through the central axis and the bearing axis of this orifice.

The planet carrier according to the invention is thus configured to improve its operating behavior and in particular its resistance to deformations caused by the transmission of forces. The impact on the bearings, such as their misalignments or their asymmetries, is thus reduced. This is made possible by the recess patterns which are formed in at least one of the discs. These recess patterns make it possible to locally reduce the stiffness (and therefore increase the flexibility) of the disc and therefore to adjust the rigidity (flexibility) of the discs, one with respect to the other. The more a disc is locally flexible, the more the softened zone is able to deform and absorb part of the energy linked to the transmission of forces. The recess patterns therefore make it possible to adjust the deformations of one of the discs with respect to the other disc, to limit their impact on the bearings.

The recess patterns are located at the mounting holes of the planet gear bearings through which the forces are transmitted. These recess patterns are preferably arranged non-symmetrically with respect to the axis of the holes and are advantageously positioned according to the direction of the forces transmitted by the planet gears. The recess patterns are therefore advantageously positioned according to the direction of rotation of the planet gears.

The benefits brought by the invention are numerous and include:

- a reduction in the misalignment of the satellite teeth with less stress on these teeth,

- reduced misalignment on the guide bearings with less stress on them,

- a reduction in satellite misalignments,

- a reduction in the mass of the satellite carrier,

- etc.

• d’un réducteur à simple étage ou à plusieurs étages ;
• d’un réducteur planétaire, épicycloïdal ou différentiel ;
• de dentures droites, hélicoïdales ou en chevron ;
• de tout type de porte-satellites monobloc ou du type cage et porte-cage ;
• de tout type de paliers de guidage des satellites, tels que à éléments roulants ou hydrodynamiques.

The present invention is compatible:

• of a single-stage or multi-stage reducer;
• of a planetary, epicyclic or differential reducer;
• straight, helical or herringbone teeth;
• of any type of single-piece or cage and cage-carrier type planet carrier;
• of any type of satellite guide bearings, such as rolling elements or hydrodynamic.

The planet carrier 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:

-- the recess patterns comprise recesses; a recess pattern may comprise one or more recesses;

-- the recesses or recess patterns are cut or crossed by circumferences centered on the first axis and passing through these orifices;

• le motif d’évidement présente un seul évidement ou présente une seule série d’évidements situé(e) sur un côté de l’orifice de palier ;
• le motif d’évidement comprend deux évidements (298) ou deux séries d’évidements situés de part et d’autre de cet orifice de palier ;
• les deux évidements ou les deux séries d’évidements sont différents par leurs formes et/ou leurs dimensions ;
• le motif d’évidement est une fente oblongue incurvée, ou est une série de trous s’étendant selon une ligne incurvée ;
• la fente oblongue comprend une branche principale qui s’étend de façon allongée et incurvée autour de l’orifice de palier, et des branches secondaires qui s’étendent transversalement vis-à-vis de la branche principale ;
• les branches secondaires sont au nombre de trois, deux branches secondaires s’étendant aux extrémités longitudinales de la branche principale, et la troisième branche secondaire s’étendant au milieu de la branche principale ;
• le motif d’évidement comprend entre deux et dix trous ;
• au moins certains des évidements du motif d’évidement sont non débouchants (ou borgnes) en direction axiale ;

-- the recesses or recess patterns extend around the orifices or are distributed around these orifices;

• the recess pattern has a single recess or has a single series of recesses located on one side of the bearing hole;
• the recess pattern comprises two recesses (298) or two series of recesses located on either side of this bearing orifice;
• the two recesses or the two series of recesses are different in their shapes and/or their dimensions;
• the recess pattern is a curved oblong slot, or is a series of holes extending in a curved line;
• the oblong slot comprises a main branch which extends in an elongated and curved manner around the bearing hole, and secondary branches which extend transversely with respect to the main branch;
• the secondary branches are three in number, two secondary branches extending from the longitudinal ends of the main branch, and the third secondary branch extending from the middle of the main branch;
• the recess pattern includes between two and ten holes;
• at least some of the recesses of the recess pattern are non-opening (or blind) in the axial direction;

-- at least some of the recesses of the recess pattern are axially open;

-- at least some of the recesses in the recess pattern have varying depth;

- at least some of the recesses of the recess pattern are arranged symmetrically with respect to other identical recesses located on a second face axially opposite the first face of the disc comprising these recesses;

-- the planet carrier is of the monobloc type,

-- the planet carrier is of the cage and cage holder type, the two discs and the bridges forming the cage.

The present invention also relates to a mechanical reducer for an aircraft turbomachine, comprising a planet carrier according to one of the preceding claims, the reducer further comprising:

- a solar which is centered on the central axis and which is mounted between the discs of the planet carrier,

- satellites which are centered on the bearing axes and mounted between the discs of the planet carrier, the satellites being guided in rotation by bearings whose opposite axial ends are housed respectively in the first and second bearing holes of the discs, and

- a crown centered on the central axis and extending around the sun and the satellites, the satellites being meshed with the sun and the crown.

The invention further relates to a turbomachine, in particular for an aircraft, comprising a reducer as described above.

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:

FIG. 1 there FIG. 1 is a schematic axial sectional view of a turbomachine using the invention;

FIG. 2 there FIG. 2 is a schematic axial sectional view of a mechanical reducer;

FIG. 3 there FIG. 3 is a perspective view of a cage and cage carrier assembly forming a mechanical reducer planet carrier;

FIG. 4 there FIG. 4 is a partial axial sectional view of a part of the planet carrier of the FIG. 3 ;

FIG. 5 there FIG. 5 is a detail view of the FIG. 4 ;

FIG. 6 there FIG. 6 is a partial schematic front view of the planet carrier of the FIG. 3 ;

FIG. 7 there FIG. 7 is a view similar to that of the FIG. 6 and illustrates an embodiment of a planet carrier according to the invention;

FIG. 8 there FIG. 8 is a view similar to that of the FIG. 6 and illustrates an alternative embodiment of a satellite carrier according to the invention;

FIG. 9 there FIG. 9 is a view similar to that of the FIG. 6 and illustrates another variant embodiment of a satellite carrier according to the invention;

FIG. 10 there FIG. 10 is a view similar to that of the FIG. 6 and illustrates an alternative embodiment of a satellite carrier according to the invention;

FIG. 11 there FIG. 11 is a partial schematic view in section and perspective of the planet carrier of the FIG. 10 ;

FIG. 12 there FIG. 12 is a view similar to that of the FIG. 11 and illustrates another variant embodiment;

FIG. 13 there FIG. 13 is a view similar to that of the FIG. 6 and illustrates another variant embodiment of a satellite carrier according to the invention;

FIG. 14 there FIG. 14 is a view similar to that of the FIG. 6 and illustrates another alternative embodiment of a satellite carrier according to the invention; and

FIG. 15 there FIG. 15 is a view similar to that of the FIG. 6 and illustrates another variant embodiment of a planet carrier according to the invention.

Detailed description of the invention

There FIG. 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.

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

Although the following description concerns a planetary or epicyclic type reducer, it also applies to a mechanical differential in which its three essential components, namely the planet carrier, the crown 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.

The reducer 10 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 10. 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.

There FIG. 1 shows part of a reducer 10 which can take the form of different architectures depending on whether certain parts are fixed or rotating. At the input, the reducer 10 is connected to the LP shaft 3, for example via splines 7. Thus, the LP shaft 3 drives a planetary pinion called the sun gear 11. Conventionally, the sun gear 11 whose axis of rotation coincides with the X axis of the turbomachine 1, drives a series of pinions called satellites 12, which are equally distributed on the same diameter around the axis of rotation X. This diameter is equal to twice the operating center distance between the sun gear 11 and satellites 12. The number of satellites 12 is generally defined between three and seven for this type of application.

All of the satellites 12 are held by a frame called a planet carrier 12. Each satellite 12 rotates around its own Y axis, and meshes with the crown 14.

• Dans une configuration épicycloïdale, l’ensemble des satellites 12 entraine en rotation le porte-satellite 13 autour de l’axe X de la turbomachine. La couronne 14 est fixée au carter moteur ou stator 5 via un porte-couronne 15 et le porte-satellites 12 est fixé à l’arbre de soufflante 4.
• Dans une configuration planétaire, l’ensemble des satellites 12 est maintenu par un porte-satellites 12 qui est fixé au carter moteur ou stator 5. Chaque satellite entraine la couronne qui est rapportée à l’arbre de soufflante 4 via un porte-couronne 15.

At the output of reducer 10, we have:

• In an epicyclic configuration, the set of satellites 12 rotates the planet carrier 13 around the axis X of the turbomachine. The crown 14 is fixed to the engine casing or stator 5 via a crown carrier 15 and the planet carrier 12 is fixed to the fan shaft 4.
• In a planetary configuration, all of the planet gears 12 are held by a planet gear carrier 12 which is fixed to the engine casing or stator 5. Each planet gear drives the crown wheel which is attached to the fan shaft 4 via a crown wheel carrier 15.

Each satellite 12 is mounted to rotate freely using a bearing 8 around a Y axis. The Y axes of rotation of the satellites 12 are distributed around the X axis and parallel to this X axis. The bearings 8 are for example of the rolling bearing type or hydrodynamic bearings. Each bearing 8 is mounted on a physical axis 13a of the planet carrier 12 and all these physical axes 13a are positioned relative to each other using one or more structural frames of the planet carrier 12. There are a number of physical axes 13a and bearings 8 equal to the number of satellites 12. For reasons of operation, assembly, manufacturing, control, repair or replacement, the axes 13a and the frame can be separated into several parts.

• Une demi-couronne avant 14a constituée d’une jante 14aa et d’une demi-bride de fixation 14ab. Sur la jante 14aa se trouve l’hélice avant de la denture du réducteur. Cette hélice avant engrène avec celle du satellite 12 qui engrène avec celle du solaire 11.
• Une demi-couronne arrière 14b constituée d’une jante 14ba et d’une demi-bride de fixation 14bb. Sur la jante 14ba se trouve l’hélice arrière de la denture du réducteur. Cette hélice arrière engrène avec celle du satellite 12 qui engrène avec celle du solaire 11.

For the same reasons mentioned above, the teeth of a reducer can be separated into several helices. In our example, we detail the operation of a 10 multi-helix reducer with a crown separated into two half-crowns:

• A front half-crown 14a consisting of a rim 14aa and a half-fixing flange 14ab. On the rim 14aa is the front helix of the reduction gear teeth. This front helix meshes with that of the satellite 12 which meshes with that of the solar 11.
• A 14b rear half-crown consisting of a 14ba rim and a 14bb half-fixing flange. On the 14ba rim is the rear helix of the reduction gear teeth. This rear helix meshes with that of the satellite 12 which meshes with that of the solar 11.

The half-flange 14ab of the front crown 14a and the half-flange 14bb of the rear crown 14b form the crown fixing flange 14c. The crown 14 is fixed to the crown carrier 15 by assembling the crown fixing flange 14c and the crown carrier fixing flange 15a using a bolted assembly for example. In the following, a half-flange may be called a flange.

The arrows of the FIG. 1 describe the oil routing in the reducer 10. The oil arrives in the reducer 10 from the stator part 5 in the distributor 16 by different means which will not be specified in this view because they are specific to one or more types of architecture. The distributor 16 is separated into two parts, generally each repeated by the same number of satellites. The injectors 17a have the function of lubricating the teeth, and the arms 17b have the function of lubricating the bearings 8. The oil is brought towards the injector 17a to exit through the end 17c in order to lubricate the teeth. The oil is also supplied to each arm 17b and circulates via the supply port 17d of the bearing 8. The oil then circulates through the axis 13a in one or more buffer zones 13b and then exits through orifices 13c in order to lubricate the bearings 8 of the satellites.

The satellite carrier 13 of the FIG. 2 is formed from a single piece in the example shown.

In figures 3 to 6, the elements already described in the above are designated by the same references increased by one hundred.

Figures 3 to 5 represent a particular technology of planet carrier 113, this planet carrier comprising a cage 120 and a cage carrier 122 connected by ball joints.

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 radial annular walls 136, 138.

The cylindrical wall 140 is here of the double-skin type and comprises an outer skin 140a interrupted by the slots 143 and an inner skin 140b interrupted by the same slots 143. The outer skin 140a separated by five slots 143 forms five outer bridges and the inner skin 140b separated by five slots 143 forms five inner bridges. Each pair of lower and upper bridges forms a yoke to accommodate the finger 182 of the cage holder 122. In other words, the bridges of each pair define between them a housing 180 for receiving a finger 182 of the cage holder 122. The bridges provide the structural connection between the walls 136 and 138. Oblong slots 180a are made in at least one of the walls 136 and 138 so as to allow the finger 182 to pass between the inner and outer bridges. These 180a lights open into the 180 housings.

The cage 120 thus comprises an annular row of housings 180. These housings 180 receive the axial fingers 182 secured to a substantially radial annular wall 182a of 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.

Each finger 182 comprises, substantially in its middle, a ring 184 for mounting the ball joint 186 intended to be crossed by a cylindrical pin 188 carried by the cage 120.

The ring 184 has a substantially radial orientation relative to the axis X. It has a generally cylindrical shape. The cage 120 and the ball joint 186 have a thickness, measured in a radial direction relative to the axis X, which is less than the inter-bridge distance or the radial thickness of the oblong slot 180a, so as to be able to be engaged in this housing concomitantly with the finger 182 supporting these parts.

Each housing 180 is crossed by a pin 188 which has a substantially radial orientation relative to the axis X. 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 here engaged by radial translation from the inside through radial orifices of the bridges, its collar 188b being intended to come into radial support on a flat face 191 of the external bridge of the cage 120. After insertion of the pin 188 into the orifices of the bridges, until the collar 188b is pressed against the external bridge, the collar 188b is fixed to this bridge for example by screwing.

There FIG. 6 shows a detail of the discs or walls 136, 138 of the planet carrier 113. In these figures, it can be seen that the wall 138 comprises first orifices 192 centered respectively on the Y axes of rotation of the satellites of the reducer. These orifices 192 are here five in number in the example shown. The wall 136 comprises second orifices 194 centered respectively on the Y axes and therefore aligned with the orifices 192. These orifices 194 are therefore also five in number in the example shown.

When the discs or walls 136, 138 have arrangements around an orifice, these arrangements are generally symmetrical with respect to a plane passing through the X axis and the Y axis of this orifice. This is particularly the case for the lights 180a. In the FIG. 6 for example, it can be seen that the lights 180a are arranged parallel to the plane P passing through the axis X of the reducer and the axis Y of the orifice 194 located between these lights 180a.

The invention proposes an improvement to a planet carrier for a mechanical reducer of an aircraft turbomachine.

This planet carrier can be of the monobloc type as illustrated in FIG. 2 , or of the cage and cage holder type as illustrated in Figures 3 to 6. The foregoing descriptions in relation to Figures 2 to 6 may therefore be used to illustrate and describe the invention.

Furthermore, the planet carrier according to the invention can equip a reducer of a turbomachine as illustrated in FIG. 1 . The foregoing description in relation to the FIG. 1 can therefore also be used to illustrate and describe the invention.

Figures 7 to 15 illustrate several variant embodiments of a planet carrier according to the invention.

In these and the following figures, the elements already described in the above are designated by the same references increased by at least another hundred.

In these figures, the planet carrier 213 comprises:

- a first disc 236 centered on the axis X, called the central axis, and extending radially and around with respect to this central axis X, this first disc 236 comprising first bearing orifices 292 centered respectively on the bearing axes Y which are distributed circumferentially around the central axis X and parallel to this central axis X,

- a second disc 238 centered on the central axis X and parallel and axially at a distance from the disc 236, this second disc 238 comprising second bearing orifices 294 which are respectively centered on the bearing axes Y, and the number of which is equal to the number of the first bearing orifices 292, and

- bridges 296 which extend between the discs 236, 238 and connect them together, these bridges 296 being formed in a single piece with the discs 236, 238.

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 reducer in the turbomachine and to the flow of gases in the turbomachine.

The orifices 292, 294 are used to mount the satellites and in particular the satellite guide bearings, in the planet carrier 213. The bearings have longitudinal ends which are housed in these orifices 292, 294. The bearings are plain (hydrodynamic) or rolling bearings for example. These bearings are not shown in Figures 7 to 15.

The discs 236, 238 comprise first annular faces axially facing each other. The disc 236 thus comprises an annular face 236a which faces an annular face of the disc 238, the annular face of the disc 238 not being visible in the drawings and therefore not referenced.

According to the invention, at least one of these faces of the discs comprises a recess pattern 298 arranged next to one of said bearing orifices 292, 294.

The or each recess pattern comprises one or more recesses.

In the remainder of the description, “recess(s)” and “recess pattern(s)” will be used to designate the same thing.

The recesses 298 have the function of compensating for forces and deformations in order to limit or even cancel the tilting of the satellites and their bearings during operation.

These recesses 298 are preferably cut or crossed by circumferences centered on the X axis and passing through these orifices 292, 294. This means that the recesses are not located radially inside the orifices 292, 294, nor radially outside these orifices (because in this case they would not be cut by circumferences passing through these orifices), but are rather located on the sides of the orifices or even between these orifices.

These recesses 298 each have a generally curved shape around the orifice 292, 294 at which the recess 298 is located, and around the Y axis of this orifice 292, 294. Alternatively, these recesses 298 are distributed to have a generally curved shape around the orifice 292, 294 at which they are located, and around the Y axis of this orifice 292, 294.

Furthermore, the recess(es) 298 associated with each of the orifices 292, 294 are preferably arranged in a non-symmetrical manner relative to a plane P passing through the X axis as well as the Y axis of this orifice 292, 294.

There FIG. 7 shows a first embodiment of the planet carrier 213 in which the face 236a of the disc 236 comprises two recesses 298 of generally curved shape (like a slot) around each of the orifices 292 of the disc 236. A first recess 298a extends around each orifice 292 and around the Y axis of this orifice 292, at a radial distance R1 from the peripheral edge of this orifice. This first recess 298a has a width L1 and an angular extent E1. A second recess 298b extends around each orifice 292 and around the Y axis of this orifice 292, at a radial distance R2 from the peripheral edge of this orifice. This recess 298b has a width L2 and an angular extent E2.

The recesses are here diametrically opposed with respect to the Y axis of the orifice 292.

In the example shown, R1 is less than R2. L1 is greater than L2. E1 is less than E2.

The recesses 298a, 298b are preferably cut or crossed by circumferences C1, C2 centered on the axis X and passing through the orifices 292. In practice, a multitude of circumferences centered on the axis X pass through the orifices 292.

These recesses 298a, 298b are arranged in a non-symmetrical manner with respect to the plane P. They are not even symmetrical with respect to each other and with respect to the Y axis or with respect to a plane passing through this axis.

There FIG. 8 shows a variant of the embodiment of the FIG. 7 in which it can be seen that the recess 298a can have a depth U1 which is constant or which varies on the contrary. In yet another variant, the recesses could be axially open and therefore axially cross the entire thickness of the disc, unlike those illustrated in figures 7 and 8 which are of the non-opening or blind type.

There FIG. 9 shows an alternative embodiment of the planet carrier 213 in which the face 236a of the disc 236 comprises several recesses 298c which are distributed to have a generally curved shape around each of the orifices 292 of the disc 236. The recesses 298c are three in number and are circular holes in the example shown, through or non-through.

There are no recesses here diametrically opposed to the recesses 298c, relative to the Y axis of the orifice 292.

The set of recesses 298c has a width L3 and an angular extent E3, and is located at a radial distance R3 from the edge of the orifice 292.

The recesses 298c are preferably cut by circumferences C1, C2 centered on the axis X and passing through the orifices 292. These recesses 298c are arranged in a non-symmetrical manner with respect to the plane P.

There FIG. 10 shows another alternative embodiment of the planet carrier 213 in which the face 236a of the disc 236 comprises a single recess 298d which has a generally curved shape around each of the orifices 292 of the disc 236.

There are no recesses here diametrically opposite to this recess 298d, relative to the Y axis of the orifice 292.

The recess 298d has a width L4 and an angular extent E4, and is located at a radial distance R4 from the edge of the orifice 292. It can be seen in the drawings that R4 is clearly greater than R1, R2 or R3, or even greater than the radius D1 of the orifices 294 of the other disc 238.

The recess 298d is preferably cut by circumferences C1, C2 centered on the X axis and passing through the orifices 292. This recess 298d is arranged in a non-symmetrical manner with respect to the plane P.

There FIG. 11 is a sectional view of the FIG. 10 and shows the depth U2 of the recess 298d. It also shows that the face 236b of the disc 236 which is opposite the face 236a, does not include a recess in this area.

In the variant illustrated in the FIG. 12 , the face 236b of the disc 236 comprises a recess 298d' which may be identical to the recess 298d and symmetrical with respect to a plane H passing through the middle of the disc 236 and perpendicular to the axes X, Y.

Figures 13 to 15 show other variant embodiments in which the recesses are located on the disc 238 and are of the through or open-end type.

In the FIG. 13 , the disc 238 comprises several recesses 298e which are distributed to have a generally curved shape around each of the orifices 294 of the disc 238. The recesses 298e are four in number and are circular holes in the example shown.

The set of recesses 298e has a width L5 and an angular extent E5, and is located at a radial distance R5 from the edge of the orifice 294.

The recesses 298e are preferably cut by circumferences C1, C2 centered on the axis X and passing through the orifices 294. These recesses 298e are arranged in a non-symmetrical manner with respect to the plane P.

In the FIG. 14 , the disc 238 comprises several recesses 298f which are distributed to have a generally curved shape around each of the orifices 294 of the disc 238. The recesses 298f are five in number and are circular holes in the example shown. They are distributed on two curved lines extending around the Y axis, two of the recesses being located on an external line S1 and the other three being located on an external line S2 and arranged in a staggered manner relative to the two recesses located on the line S1.

The set of recesses 298f has a width L6 and an angular extent E6, and is located at a radial distance R6 from the edge of the orifice 294.

The recesses 298f are preferably cut by circumferences C1, C2 centered on the axis X and passing through the orifices 294. These recesses 298f are arranged in a non-symmetrical manner with respect to the plane P.

In the FIG. 15 , the disc 238 includes a single recess 298g which has a generally curved shape around each of the orifices 294 of the disc 238. This recess 298g is in the form of an elongated and curved slot.

The slot comprises a main branch 298g1 elongated and curved around the orifice 294, and secondary branches 298g2, 298g3 perpendicular to the main branch 298g1 and connected to this main branch. The secondary branches 298g2, 298g3 are three in number, two secondary branches 298g2 being connected to the longitudinal ends of the main branch 298g1, and the third secondary branch 298g3 being connected to the middle of the main branch 298g1.

The slot has a maximum width L7 and an angular extent E7, and is located at a radial distance R7 from the edge of the orifice 294.

In all embodiments and variants, the recesses 298 create zones of flexibility, i.e. local flexibility, around the orifices 292, 294 of the discs 236, 238. The level of flexibility can be adjusted by adjusting the dimensions of the recesses 298, and in particular by adjusting their width, their angular extent, their depth or the remaining thickness of material of the disc (by the presence of a symmetrical recess for example – FIG. 12 ), etc.

The recesses 298 are advantageously arranged according to the areas of application of the forces, which depends in particular on the direction of rotation of the satellites. Figures 7 to 15 show a direction F1 of application of the forces and a direction F2 of rotation of the satellites. It can be seen that the recesses, or at least the recesses having the largest dimensions, are located at the level of the areas of application of the forces.

Claims (14)

Planet carrier (213) for a mechanical reducer (10) of an aircraft turbomachine (1), this planet carrier (213) comprising:
- a first disc (236) centered on a central axis (X) and extending radially and around with respect to this central axis (X), this first disc (236) comprising first bearing orifices (292) centered respectively on bearing axes (Y) which are distributed circumferentially around the central axis (X) and parallel to this central axis (X),
- a second disc (238) centered on the central axis (X) and extending parallel and axially at a distance from the first disc (236), this second disc (238) comprising second bearing orifices (294) which are respectively centered on the bearing axes (Y), the number of second bearing orifices (294) being equal to the number of first bearing orifices (292),
the first and second discs (236, 238) comprising first faces (236a) which extend radially and are arranged axially opposite one another,
- bridges (296) which extend between the first and second discs (236, 238) and connect them together, the bridges (296) being formed in one piece with the first and second discs (236, 238),
characterized in that at least one of said first faces (236a) comprises a recess pattern (298) arranged next to one of said bearing orifices (292, 294), the recess pattern having a generally curved shape extending in an arc of a circle around the bearing orifice (292, 294) at which the recess pattern (298) is located, and preferably the recess pattern (298) extending in a non-symmetrical manner with respect to a radial plane (P) passing through the central axis (X) and the bearing axis (Y) of this orifice (292, 294). The planet carrier (213) of claim 1, wherein the recess pattern (298) has a single recess (298) or has a single series of recesses located on one side of the bearing hole (292, 294). The planet carrier (213) of claim 1, wherein the recess pattern comprises two recesses (298) or two sets of recesses located on either side of said bearing orifice (292, 294). A planet carrier (213) according to claim 3, wherein the two recesses (298) or the two series of recesses are different in their shapes and/or their dimensions. A planet carrier (213) according to any preceding claim, wherein the recess pattern is a curved oblong slot, or is a series of holes extending along a curved line. A planet carrier (213) according to claim 5, wherein the oblong slot comprises a main branch (298g1) which extends in an elongated and curved manner around the bearing orifice (292, 294), and secondary branches (298g2, 298g3) which extend transversely with respect to the main branch (298g1). A planet carrier (213) according to claim 6, wherein the secondary branches (298g2, 298g3) are three in number, two secondary branches (298g2) extending at the longitudinal ends of the main branch (298g1), and the third secondary branch (298g3) extending in the middle of the main branch (298g1). The planet carrier (213) of claim 5, wherein the recess pattern (298) comprises between two and ten holes. A planet carrier (213) according to any preceding claim, wherein at least some of the recesses (298) of the recess pattern are axially non-opening. A planet carrier (213) according to any preceding claim, wherein at least some of the recesses (298) of the recess pattern open out in the axial direction. A planet carrier (213) according to any preceding claim, wherein at least some of the recesses (298) have a variable depth. Planet carrier (213) according to one of the preceding claims, in which at least some of the recesses (298) are arranged symmetrically with respect to other identical recesses located on a second face (236b) axially opposite the first face (236a) of the disc (236) comprising these recesses (298). Mechanical reducer (10) for an aircraft turbomachine, comprising a planet carrier (213) according to one of the preceding claims, the reducer further comprising:
- a solar (11) which is centered on the central axis (X) and which is mounted between the discs (236, 238) of the planet carrier (213),
- satellites (12) which are centered on the bearing axes (Y) and mounted between the discs (236, 238) of the planet carrier (213), the satellites (12) being guided in rotation by bearings (8) whose opposite axial ends are housed respectively in the first and second bearing orifices (292, 294) of the discs (236, 238), and
- a crown (14) centered on the central axis (X) and extending around the sun (11) and the satellites (12), the satellites (12) being meshed with the sun (11) and the crown (14). Turbomachine (1), in particular for an aircraft, comprising a reducer (10) according to claim 13.