Speed ​​reducer for driving a turbomachine blower

Abstract

The invention relates to a speed reducer (100) for driving a turbomachine blower, comprising a sun gear (110), a ring gear (120), satellites (130), and a satellite carrier, the satellites are arranged in N stages, each nth stage comprising at least two satellites; a first stage has its satellites which mesh with the sun gear and a last stage has its satellites which mesh with the ring gear, for the satellites of an nth and an n+1th stage directly consecutive, n going from 1 to N-1, each satellite of the nth stage meshes with a satellite of the n+1st stage, so as to form gear series;the satellite carrier comprising, for each series, a radial opening (141) and an internal corridor (142) communicating with the radial opening, extending from the radial opening through the nominal locations of each of the satellites, to an internal zone (143) located beyond the nominal location of the satellite belonging to the first stage. Figure for the abbreviation: Figure 5;

Description

Title of the invention: Speed ​​reducer for driving a turbomachine blower Scope of the invention

[0001] The present invention relates to the field of aeronautics, and more specifically, to aircraft turbomachinery.

[0002] More particularly, the invention relates to a speed reducer for driving a turbomachine blower.

[0003] The invention also relates to a satellite carrier configured to be mounted in such a speed reducer.

[0004] The invention also relates to a turbomachine, in particular a turbojet with an unfaired fan, comprising such a speed reducer, and also relates to an aircraft comprising such a turbomachine.

[0005] The invention further relates to a method of mounting such a speed reducer. Prior art

[0006] It is known to use speed reducers to reduce the rotational speed of a turbomachine shaft, in particular a low-pressure shaft of a turbojet engine, to drive a turbomachine fan at a reduced speed. Such use is particularly important for turbomachines with a high bypass ratio, especially those with a very high bypass ratio.

[0007] In particular, the technique of so-called planetary type speed reducers is known, which allows for high transmission ratios while being particularly compact.

[0008] A planetary-type speed reducer comprises, in a known manner, a gear set including a central pinion, called the sun gear, a peripheral gear generally with internal teeth, called the ring gear, and a plurality of pinions arranged between the sun gear and the ring gear, called planet gears. Furthermore, such a speed reducer includes a planet carrier on which the planet gears are mounted.

[0009] When used to reduce the rotational speed of one rotating element relative to another, such a speed reducer is connected at the input to a driving rotating element, which is here in particular a turbine, via its solar element, and connected at the output to a driven rotating element, which is here in particular a blower, via its ring gear or its planet carrier.

[0010] A speed reducer connected at the output by the ring gear, with the planet carrier which is fixed against rotation, for example fixed to a turbine housing, is generally called a planetary reducer, while a speed reducer connected at the output by The ring gear, with its fixed rotational component, for example, attached to a turbine housing, is generally described as epicyclic, with the output of the speed reducer rotating in one direction or the other relative to the input direction of rotation, depending on the type of connection. The speed reducer can also be of the differential type, meaning that no component is fixed in rotation.

[0011] For example, from patent EP 3596360 B1, a speed reducer for the rotational drive of a turbomachine blower is known, the speed reducer being in particular of the epicyclic type, with the blower rotating in the same direction as the turbine.

[0012] There is a need to provide a speed reducer solution for rotating a turbomachine blower that is particularly compact and easy to mount. Description of the invention

[0013] The present invention aims to remedy all or part of the disadvantages of the prior art mentioned above.

[0014] The invention relates, according to a first aspect, to a speed reducer for driving a turbomachine fan, the speed reducer comprising a solar element, a ring gear, a plurality of satellites, and a satellite carrier supporting said satellites, the solar element being configured to be mechanically connected to a turbomachine turbine to be driven in rotation by it, and at least one of the ring gear or the satellite carrier being configured to be mechanically connected to a turbomachine fan to drive the latter in rotation, in which speed reducer: the satellites are arranged according to N stages of satellites arranged between the solar system and the corona, N being an integer, preferably even, and even more preferably equal to 2, each nth stage, n going from 1 to N, comprising at least two satellites; The speed reducer is configured to adopt an operating configuration in which the satellites are each mounted at a predetermined nominal location, in which a first of said stages, for which n=l, has each of its satellites meshing with the sun gear, and a last of said stages, for which n=N, has each of its satellites meshing with the ring gear. For the satellites of a directly consecutive nth and n+7th stage, n ranging from 1 to AM, each satellite of the nth stage meshes with a satellite of the n+7th stage, so as to form a plurality of gear sets between the sun gear and the ring gear. The satellite carrier includes, for each gear set, a radial opening configured to allow the radial introduction of each of the satellites in the set. gear in the satellite carrier s, as well as an internal corridor communicating with the radial opening and extending from the radial opening through the nominal locations of each of the satellites in the gear series, to an internal area of ​​the satellite carrier located beyond the nominal location of the satellite belonging to the first stage, for which n=l\ the speed reducer is further configured to adopt a mounting configuration, in which the satellites are introduced into the satellite carrier and positioned in the internal channels at mounting locations beyond their nominal locations, so that the satellites of the last stage, for which n=N, have the crown circle of their teeth circumscribed within the crown circle; thanks to which the satellite carrier equipped with the satellites can be introduced into the ring and then move into its operating configuration by moving the satellites to their nominal locations.

[0015] Thus, the speed reducer according to the invention is particularly compact in the operating configuration, while allowing easy mounting of the planet carrier in the ring.

[0016] The internal corridors allow pre-assembly of the satellites in the satellite carrier so that the satellite carrier equipped with the satellites can be introduced into the crown, with the head circles of the teeth of the satellites of the last stage being located inside the head circle of the crown, which has internal teeth.

[0017] These channels also allow guided movement of each of the satellites to their nominal locations, to finalize the assembly of the speed reducer once the satellite carrier equipped with the satellites is introduced into the ring.

[0018] In the operating configuration, the satellites of the last stage have teeth, in particular their second set of teeth, which mesh with the teeth of the crown, and may also have another set of teeth or any other element which protrudes radially from the head circle of the teeth of the crown.

[0019] Such a planet carrier is particularly advantageous for speed reducers with 2 or more stages, and in particular for speed reducers with an even number of stages, although by no means limited to such speed reducers.

[0020] The invention thus also relates, according to a second aspect, to a planet carrier configured to equip a speed reducer as described above, and which comprises, for each gear set, a radial mounting opening configured to allow the radial introduction of each of the planets of the gear set into the planet carrier, as well as an internal channel communicating with the radial mounting opening and extending from the radial mounting opening through the nominal locations of each of the planets. the gear series, up to an internal area of ​​the satellite carrier located beyond the nominal location of the satellite belonging to the first stage, for which n=l.

[0021] Other preferential, particularly convenient and advantageous features of the speed reducer according to the invention are described below.

[0022] According to a preferred embodiment, the internal channel of each of the gear series has consecutive portions substantially straight and arranged in a bent manner with respect to each other, each nth portion of the internal channel, n going from 1 to N, being configured to allow a displacement of a satellite of the nth stage of the gear series at least between its nominal location and its mounting location.

[0023] According to a preferred embodiment, the internal corridors of each of the gear series communicate with a central cavity of the satellite carrier configured to accommodate the solar array and / or the internal corridors of each of the gear series communicate directly with each other.

[0024] According to a preferred embodiment, the crown, and / or the solar, and / or the satellites, and / or the satellite carrier, are monobloc.

[0025] According to a preferred embodiment, the satellites each comprise a first set of teeth and a second set of teeth, said teeth being coaxial and distinct from each other, each of the meshes between two satellites of directly consecutive stages being formed by the first set of teeth of a satellite belonging to a first of said stages and the second set of teeth of a satellite belonging to a second of said stages, the first set of teeth of the satellites of the last stage, for which n=N, having a nominal circle radially exceeding the nominal circle of the ring in the operating configuration of the speed reducer.

[0026] According to a preferred embodiment, the solar is configured to be driven in rotation by a low pressure turbomachine shaft, and in which the first tooth of each of the satellites is a driven tooth and the second tooth of each of the satellites is a driving tooth.

[0027] According to a preferred embodiment, the satellite carrier comprises, for each of the satellites of the AMth stage, a bearing shaft and a pair of bearings, for mounting each of the satellites of the AMth stage on the satellite carrier, said bearings being mounted under the first toothing of each of the satellites of the AAth stage.

[0028] In particular, the satellite carrier comprises, for each of the satellites of the (2 pj-th stage, p ranging from 1 to N / 2, a bearing shaft and a pair of bearings, for mounting each of the satellites of the f2pj-th stage on the satellite carrier, said bearings being mounted under the first toothing of each of the satellites of the (2pj-th stage.

[0029] According to one example, the satellite carrier s comprises, for each of the satellites of the (2 p) -th stage, p ranging from 1 to N / 2, a bearing axis and a single bearing, or more than two bearings.

[0030] According to a preferred embodiment, at least one of said bearings has a spacer portion extending axially, said bearing shaft comprises a first portion having a first diameter and a second portion having a second diameter greater than the first diameter and a shoulder between said first and second portions, the bearing shaft being configured to be mounted by its first and second portions in corresponding mounting openings of the planet carrier, said bearings being configured to be mounted on the first portion of the bearing shaft with one of the bearings abutting said shoulder and with the bearings coming into contact with each other through said spacer portion.

[0031] Thus, during assembly, the satellites of the A-th stage are mounted in the satellite carrier according to a floating mount, then the assembly is finalized according to a tight mount between the satellite carrier and said shoulder, for example by tightening the bearing shaft against the satellite carrier, for example by means of a nut.

[0032] According to a preferred embodiment, the satellite carrier comprises, for each of the satellites of the nth stages, n from 1 to N-1, a bearing block comprising a bearing shaft and a pair of bearings, the bearing block being configured to be mounted in a mounting opening of the satellite.

[0033] In particular, the satellite carrier comprises, for each of the satellites of the (2p-1)th stages, p ranging from 1 to N / 2, a bearing block comprising a bearing shaft and at least one bearing or a pair of bearings, the bearing block being configured to be mounted in a mounting opening of the satellite.

[0034] According to one example, the satellite carrier s comprises, for each of the satellites of the (2p-1) -th stage, p ranging from 1 to N / 2, a bearing block comprising a bearing shaft and a single bearing, or more than two bearings.

[0035] According to a preferred embodiment, the bearing block is monobloc, the bearing shaft comprising a first mounting portion and a second mounting portion and the bearings being arranged between said first and second portions, the bearing shaft being configured to be mounted by its first mounting portion and its second mounting portion in corresponding mounting openings of the satellite carrier, and the first mounting portion having a first diameter less than a diameter of the mounting opening of the satellite, and the second mounting portion having a second diameter greater than the first diameter and greater than the diameter of the mounting opening of the satellite.

[0036] Thus, the satellite can be pre-mounted on the bearing block, which can itself be tightly mounted on the satellite port.

[0037] The invention also relates, according to a second aspect, to a turbomachine, preferably a turbojet with an unfaired fan, comprising a turbine, a fan and a speed reducer as described above, the speed reducer being connected at the inlet to the turbine via its solar array, so as to be able to be driven in rotation by the turbine, and connected at the outlet to the fan via at least one of its ring gears and its planet carrier, so as to be able to drive the fan in rotation.

[0038] The invention also relates, according to a third aspect, to a fixed-wing aircraft comprising a turbomachine as described above.

[0039] The invention also relates, according to a fourth aspect, to a method of mounting a speed reducer as described above, comprising: - a step of introducing all the satellites of each gear series into the planet carrier via the radial opening of each gear series, so that the planet carrier is in its mounting configuration; - a step of positioning the satellite carrier in the ring; - a step of moving and mounting the satellites to their nominal locations, so that the satellite carrier is in its operating configuration.

[0040] According to a preferred embodiment, the process further comprises: - a pre-assembly step of the bearings in the satellites at least of the last stage, for which n=N, upstream of the introduction step and; in which the movement and assembly stage includes the insertion of the bearings into the satellites of the nth stages, "ranging from 1 to N-1, as well as the insertion of the bearing shafts into each of the satellites and into the corresponding mounting openings of the satellite carrier.

[0041] In particular, the method may include: - a pre-assembly step of the bearings in the satellites at least of the (2 p)th stage, p ranging from 1 to N / 2, upstream of the introduction step and; in which the movement and assembly stage includes the insertion of the bearings into the satellites of the (2p-l)th stages, from 1 to N / 2, as well as the insertion of the bearing shafts into each of the satellites and into the corresponding mounting openings of the satellite carrier.

[0042] The invention also relates, according to a fifth aspect, to a planet carrier configured to be mounted in a speed reducer as described above, comprising, for each set of gears, a radial opening configured for permit radial introduction of each of the gear series satellites into the satellite carrier, as well as an internal corridor communicating with the radial opening and extending from the radial opening through the nominal locations of each of the gear series satellites, to an internal area of ​​the satellite carrier located beyond the nominal location of the satellite belonging to the first stage, for which n=l. Brief description of figures

[0043] The invention will be better understood, and other details, advantages and features thereof will become apparent from the following description, given by way of non-limiting example and with reference to the accompanying drawings, in which:

[0044] [Fig.1] is a schematic cross-sectional view of a turbomachine comprising a speed reducer according to the invention;

[0045] [Fig.2] is a schematic detailed cross-sectional view of the turbomachine of [Fig.1] at the speed reducer;

[0046] [Fig.3] is a schematic perspective view of the speed reducer according to one embodiment, on which the planet carrier is not visible;

[0047] [Fig.4] is a schematic view of the speed reducer in an operating configuration, according to a cross-section;

[0048] [Fig.5] is a schematic view of the speed reducer in a mounting configuration, according to a cross-section;

[0049] [Fig.6] is a schematic view of the speed reducer along a longitudinal section, at the level of a satellite of the last stage of the speed reducer;

[0050] [Fig.7] is a schematic view of the speed reducer along a longitudinal section, at the level of a satellite of the first stage of the speed reducer;

[0051] [Fig.8] is a synoptic diagram of a method for mounting a speed reducer according to the invention.

[0052] Detailed description of preferred embodiments

[0053] The present description is given by way of non-limiting agreement, each feature of an embodiment being able to be advantageously combined with any other feature of any other embodiment, according to any technically functional combination.

[0054] It should be noted from the outset that the figures are not necessarily to scale.

[0055] Fig. 1 schematically illustrates a turbomachine 1 of the turbojet type with a blower (called a turbofan in English terminology) according to a half longitudinal section view.

[0056] The turbomachine 1 extends along a longitudinal axis X, corresponding to an axis of rotation of the rotating elements of the turbomachine 1.

[0057] In a known manner, the turbomachine 1 here comprises a low-pressure stage and a high-pressure stage, and thus includes a low-pressure compressor 2 and a high-pressure compressor 3 together forming the compressor, a combustion chamber 4, a high-pressure turbine 5, and a low-pressure turbine 6 together forming the turbine. The turbomachine 1 includes a low-pressure shaft 7, to which the low-pressure compressor 2 and the low-pressure turbine 6 are connected, and together form an external propulsion coil. The turbomachine 1 also includes a high-pressure shaft 8, to which the high-pressure compressor 3 and the high-pressure turbine 5 are connected, and together form an internal propulsion coil. The low-pressure shaft 7 and the high-pressure shaft 8 are collinear with their longitudinal axis X and are mounted on bearings on a housing 9 of the turbomachine 1.

[0058] The turbomachine 1 also includes a fan 10 which is configured to be driven in rotation by means of the turbine, and in particular by the low-pressure shaft 7. The turbomachine 1 here includes a fan shaft 11, on which the fan 10 is mounted.

[0059] In the illustrated example, the housing 9 includes a fairing 12 which surrounds the blower 10, which is said to be faired, however the housing 9 may also be without a fairing 12 and the blower is then said to be unfaired.

[0060] The turbomachine 1 further includes a speed reducer 100, through which the blower 10 is driven in rotation with a reduced speed compared to the rotation speed of the low pressure shaft 7.

[0061] The speed reducer 100 is here a planetary type speed reducer. It is specified here that its input and output connections can be of any type, including planetary, epicyclic, or differential.

[0062] Fig. 2 represents a detailed view of Fig. 1, at the level of the speed reducer 100, and on which certain elements have been omitted or simplified.

[0063] The speed reducer 100 comprises a central pinion, which is called the sun gear 110, an internally toothed gear, which is called the ring gear 120, and a plurality of pinions, which are called planet gears 130 and which are arranged between the sun gear 110 and the ring gear 120. The speed reducer 100 further comprises a planet carrier s 140, on which the planet gears 130 are mounted freely in rotation, for example by means of bearings, which may be of the rolling or plain bearing type, preferably mounted under the teeth of the planet gears 130, as described in more detail below.

[0064] The speed reducer 100 is connected at the input to the low pressure shaft 7 via the solar 110.

[0065] In the illustrated example, the speed reducer 100 is connected at the output to the blower shaft 11 via the ring 120. The planet carrier 140 is fixed in rotation here, and is connected to the housing 9. The speed reducer 100 illustrated is thus said to be of the planetary type, with the blower 10 rotating in the same direction as the turbine.

[0066] However, according to an unillustrated variant, the speed reducer 100 can also be connected at the output to the blower shaft 11 via the planet carrier 140, with the ring 120 which is fixed in rotation, and connected to the housing 9. In this variant, the speed reducer 100 is said to be of epicyclic type, with the blower 10 which rotates in the opposite direction to that of the turbine.

[0067] According to yet another variant not illustrated, the speed reducer 100 can also be connected at the output to the blower shaft 11 via one of the ring 120 and the planet carrier 140, with the other of the ring 120 and the planet carrier 140 being free to rotate, and in particular not connected to the housing 9. In this variant, the speed reducer 100 is said to be of the differential type (or compound in English terminology), and the blower 10 rotates in the same direction as the turbine if the blower 10 is connected to the ring 120, and in the opposite direction to that of the turbine if the blower 10 is connected to the planet carrier 140.

[0068] The speed reducer 100 comprises a plurality of satellites 130 arranged in a number N of satellite stages, N being an even number. The satellite stages are hereafter referred to as En, with n an integer from 1 to N.

[0069] The speed reducer 100 can however also include a number N of satellite stages with N which is any natural number, in particular odd.

[0070] In the illustrated example, N is equal to two, that is to say that the speed reducer 100 comprises two satellite stages 130, namely a first stage El and a second stage E2.

[0071] Each stage En comprises at least two satellites 130, and preferably three satellites 130.

[0072] The stages En are arranged between the solar element 110 and the ring 120. The first stage El has each of its satellites 130 that mesh with the solar element 110. The last stage E^V has each of its satellites that mesh with the ring 120. In addition, for the satellites of a stage En and a stage En+7 that are directly consecutive, with n ranging from 1 to N-1, each satellite of the stage En meshes with a satellite of the stage En+7. This results in a gearing between the solar element 110 and the ring 120, comprising a plurality of gear sets formed by the meshing of each of the satellites 130 with each other, between the solar element 110 and the ring 120. Each gear set here comprises A+7 meshings.

[0073] Thus, in the illustrated example, the satellites 130 of the first stage E1 mesh with the solar array 110, and the satellites 130 of the second stage E2 mesh with the corona 120, and the 130 satellites of the first stage El each mesh with a 130 satellite of the second stage E2 directly following the first stage El.

[0074] In particular, each stage En preferentially comprises the same number M of satellites 130, each satellite of the stage En meshing one by one with exactly one distinct satellite of the stage En+7. In such a case, the speed reducer 100 comprises M series of gears each comprising A+7 meshes.

[0075] In the speed reducer 100, the satellites 130 of each stage are arranged on concentric circles, and the centers of the solar element 110, the ring 120, and the centers of said concentric circles coincide. Thus, the reducer includes an axial direction, which corresponds to the same axis of rotation of the solar element 110 and the ring 120, as well as the axis of revolution of the satellites 130 around the solar element 110. The axial direction of the speed reducer corresponds here to the longitudinal axis X of the turbomachine 1.

[0076] Fig. 3 illustrates the speed reducer 100 according to an example of an embodiment, shown in a so-called operating configuration, in which the solar 110, the satellites 130 and the ring 120 mesh and in which the speed reducer is able to drive the blower 10 in rotation.

[0077] The speed reducer 100 illustrated in [Fig. 3] comprises a first stage El and a second stage E2 of satellites 130 (symbolized by concentric circles of the centers of the satellites 130 of each stage, in dashed lines), each stage here comprising three satellites 130. Each of the satellites 130 of the first stage El, hereafter referred to as satellites 130-1, meshes with exactly one other satellite 130 of the second stage E2, the satellites 130 of the second stage E2 being hereafter referred to as 130-2. The speed reducers 100 thus each comprise three sets of three meshes between the solar element 110 and the ring gear 120.

[0078] In the illustrated embodiment, the satellites 130 each comprise a first set of teeth 131 and a second set of teeth 132, which are coaxial and distinct from each other. It should be noted that in [Fig. 3], the teeth of the teeth 131 and 132 are not visible, and only the tracks of the teeth 131 and 132 are shown.

[0079] Each of the meshes between two satellites of directly consecutive stages is formed by the first tooth 131 of a satellite belonging to a first of the stages and the second tooth 132 of a satellite belonging to a second of the stages.

[0080] In the illustrated example, the first gear 131 of each of the satellites 130-2 of the second stage E2 meshes with the second gear 132 of the satellites 130-1 of the first stage EL

[0081] The first tooth 131 of the satellites 130-1 of the first stage El meshes with the tooth of the solar 110, and the second tooth 132 of the satellites 130-2 of the second stage E2 meshes with the tooth of the ring 120.

[0082] Thus, the first tooth 131 of the satellites 130 is here a driven tooth and the second tooth 132 of the satellites 130 is a driving tooth.

[0083] In particular, the meshing between the solar 110 and the satellites 130-1 of the first stage El, and the meshing between the satellites 130-2 of the second and last stage E2 and the ring, are arranged in the same plane PI orthogonal to the axial direction of the speed reducer, and thus to the longitudinal axis X of the turbomachine 1.

[0084] The speed reducer 100 can be substantially symmetrical with respect to a plane of symmetry Ps substantially orthogonal to the axial direction of the speed reducer. In particular, the gears of the speed reducer 100 can be doubled, on either side of the plane of symmetry Ps.

[0085] In particular, for each of the satellites 130 of a 2p-l, or 2p, stage, respectively, p ranging from 1 to N / 2, one of the first gear teeth 131, or second gear teeth 132, or second gear teeth 132, or first gear teeth 131, respectively, comprises two distinct tracks arranged on either side of the other, one of the first gear teeth 131, or second gear teeth 132, or second gear teeth 132, or first gear teeth 131, which comprises a single track. The single track may, however, also be formed by two juxtaposed distinct tracks.

[0086] The speed reducer 100 here has a so-called "grouped" configuration, in which the meshing between the solar element 110 and the satellites 130-1 of the first stage El, and the meshing between the satellites 130-2 of the second and final stage E2 and the ring, are located in the same plane PI, corresponding to the plane of symmetry Ps. The meshing between the satellites 130-1 of the first stage El and the satellites 130-2 of the second stage E2, is here split and located in the same planes Pl-1 and P1-2 orthogonal to the axial direction of the speed reducer, situated on either side of the plane of symmetry Ps.

[0087] The second toothing 132 of each of the satellites 130-1 of the first stage El comprises a first track 132-1 and a second track 132-2 located on either side of the single track of the first toothing 131. In particular, the tracks 132-1 and 132-2 are respectively located in the planes Pl-1 and P1-2.

[0088] The first tooth 131 of each of the satellites 130-2 of the second stage E2 has a first track 131-1 and a second track 131-2 located on either side of the single track of the second tooth 132. In particular, the tracks 131-1 and 131-2 are respectively located in the Pl-1 and P1-2 planes.

[0089] The crown 120 is monobloc, that is to say in one piece, and is arranged in the plane of symmetry Ps.

[0090] According to an embodiment not illustrated, the speed reducer 100 has a so-called "spread-out" configuration, in which the meshing between the solar array 110 and the satellites 130-1 of the first stage El, and the meshing between the satellites 130-2 of the The second and final stage E2 and the 120 ring are duplicated on either side of the symmetry plane Ps and arranged in the same planes Pl-1 and Pl-2 orthogonal to the axial direction of the speed reducer, located on either side of the symmetry plane Ps. The meshing between the 130-1 satellites of the first stage El and the 130-2 satellites of the second stage E2 is located in the same plane orthogonal to the axial direction, corresponding here to the symmetry plane Ps.

[0091] The first tooth 131 of each of the satellites 130-1 of the first stage El comprises a first track 131-1 and a second track 131-2 located on either side of the single track of the second tooth 132. In particular, the tracks 131-1 and 131-2 are respectively located in the planes Pl-1 and Pl-2.

[0092] The second toothing 132 of each of the satellites 130-2 of the second stage E2 comprises a first track 132-1 and a second track 132-2 located on either side of the single track of the first toothing 131. In particular, the tracks 132-1 and 132-2 are respectively located in the Pl-1 and Pl-2 planes.

[0093] In this embodiment, the ring 120 comprises a first track 120-1 and a second track 120-2, each meshing respectively with the tracks 132-1 and 132-2 of the second gear set of each of the satellites 130-2 of the second stage E2. In particular, the ring 120 may comprise two distinct half-rings, each comprising one of the tracks 120-1 and 120-2. The two half-rings are here arranged here, each in one of the planes Pl-1 and Pl-2, on either side of the plane of symmetry Ps.

[0094] Regardless of the embodiment, gears comprising a single track, arranged in the plane of symmetry Ps, are preferably of the straight, helical, or herringbone type. Gears comprising two distinct tracks, arranged in planes Pl-1 and Pl-2, are preferably of the straight or herringbone type.

[0095] In a planetary configuration, in which the solar 110 and the corona 120 are co-rotating, the speed reducer 100 is preferably configured so that the absolute transmission ratio between the solar 110 and the corona 120 is less than or equal to approximately 1 / 5. In other words, the reduction ratio between the solar 110 and the corona 120 is greater than or equal to 5.

[0096] In an epicycloidal configuration, in which the solar 110 and the planet carrier 140 are counter-rotating, the speed reducer 100 is preferably configured so that the absolute transmission ratio between the solar 110 and the planet carrier 140 is less than or equal to approximately 1 / 6. In other words, the reduction ratio between the solar 110 and the ring 120 is greater than or equal to 6.

[0097] Figures 4 and 5 schematically represent the speed reducer 100 in a cross-sectional view, orthogonal to the longitudinal axis X, respectively in the operating configuration and in a mounting configuration. In these figures, only a series of gears is shown as an example.

[0098] In [Fig.4], the satellites 130 (here 130-1 and 130-2) are each positioned at a nominal location, allowing the operation of the speed reducer 100. The nominal location of the satellite 130-1 of the El stage and of the satellite 130-2 of the E2 stage is symbolically represented by the nominal positions of the centers of these satellites, referenced respectively N1 and N2 in Figures 4 and 5.

[0099] In [Fig.5], the satellites 130 (here 130-1 and 130-2) are each positioned at a mounting location, allowing the mounting of the speed reducer 100 and in particular the insertion of the satellite carrier 140 into the ring 120. The mounting location of the satellite 130-1 of the El stage and of the satellite 130-2 of the E2 stage is symbolically represented by the mounting positions of the centers of these satellites, referenced respectively M1 and M2 in Figures 4 and 5.

[0100] The satellite carrier 140 here has a general circular cylindrical shape, and is at least partially hollow, in which the satellites 130 are arranged.

[0101] The satellite carrier 140 has a plurality of radial mounting openings 141, located on the periphery of the satellite carrier.

[0102] In the illustrated example, each of the gear sets includes such a radial mounting opening 141, i.e. the planet carrier includes three radial mounting openings 141, here regularly distributed around the periphery of the planet carrier.

[0103] The satellite carrier 140 also includes a plurality of internal corridors 142 for each of the gear series, each internal corridor 142 communicating with a radial opening 141 and extending from this radial opening 141 each to an internal area 143 of the satellite carrier, this internal area 143 being located beyond the nominal location of the satellite 130-1 of the first stage El, the internal corridor 142 further passing through the nominal locations of each of the satellites of the gear series.

[0104] In the illustrated example, each internal corridor 142 therefore extends from the radial opening 141 of the gear series, to the internal zone 143 passing through the nominal locations of the satellites 130-1 and 130-2, i.e. passing here through the nominal positions NI and N2.

[0105] By an internal zone 143 located beyond the nominal location of the satellite 130-1 of the first stage EL, it is understood that the location of the internal zone 143 is situated on a side opposite to the radial opening 141, with respect to the nominal location of the satellite 130-1 of the first stage EL

[0106] The mounting locations of each of the satellites are located beyond the nominal locations of each of the satellites, in the internal corridors 142.

[0107] A mounting location situated beyond the nominal locations of the satellites is understood to mean that for a stage n satellite, n ranging from 2 to N, the mounting location is situated between its nominal location and the nominal location of the stage n-1 satellite. For the first-stage satellite, the mounting location is situated at the level of the internal zone 143, located beyond the nominal position of the first-stage satellite, starting from the radial opening 141.

[0108] In the illustrated example, the mounting position M1 of the first stage satellite El is at the internal area 143, and the mounting position M2 of the second stage satellite E2 is located between the nominal position NI and the nominal position N2.

[0109] As can be seen in Figures 4 and 5, the internal corridors 142, here three in number, have a generally angled shape. Each of the internal corridors 142 having this angled shape comprises a plurality of consecutive, substantially straight portions arranged at an angle to one another.

[0110] Generally, each internal corridor 142 comprises N portions, and each nth portion, n from 1 to N, is configured to allow at least the movement of the satellite of the nth stage of the gear series, between its nominal location and its mounting location.

[0111] In the illustrated example, the internal corridor 142 comprises two portions, namely a first portion 142-1 in which the satellite 130-1 of the first stage El can move at least between its nominal position NI and its mounting position M1, and a second portion 142-2 in which the satellite 130-2 of the first stage E2 can move at least between its nominal position N2 and its mounting position M2.

[0112] In addition, the second portion 142-2 is also configured to allow the movement of the satellite 130-1 from the first stage El to the first portion 142-1.

[0113] The portions of an internal corridor 142 may in particular be generally oblong in shape, and each have a width which is substantially greater than the diameter of the largest satellite to be moved on the portion.

[0114] In the illustrated example, the internal corridors 142 communicate with each other at the level of their second portions 142-2.

[0115] The satellite carrier 140 also includes a central cavity in which the solar 110 is housed, and which here communicates with the second portions 142-2.

[0116] Here, the second portions 142-2 and the central cavity which communicate together form a single cavity comprising three branches opening onto the radial openings 141, as can be seen in solid lines in figures 4 and 5, the contours fictitious interiors of the internal corridors 142 being represented in dashed lines on these figures.

[0117] Alternatively, according to an unillustrated variant, the second portions 142-2 may not communicate with each other, communicating with the central cavity only at the level of a reduced opening in the second portions 142-2, provided to allow the interlocking between the satellites 130-1 of the first stage El with the solar 110.

[0118] The internal corridors 142 are delimited by walls 144 which comprise the satellite carrier 140, and are comma-shaped in figures 4 and 5. The walls 144 can be solid, or hollow which makes it possible to lighten the satellite carrier.

[0119] The satellite carrier 140 can in particular be monobloc, that is to say that it is made in one piece.

[0120] For example, the satellite carrier 140 can be manufactured in the general form of a circular cylinder, in which the internal channels are machined according to N machining steps by material removal.

[0121] The satellite carrier 140 illustrated in figures 4 and 5 can be produced by a first machining step, in particular milling, in which material is removed in a first direction to form the second outermost portion 142-2 of the internal channel 142, and a second machining step, in particular milling, in which material is removed in a second direction, with a different inclination than the first direction, to form the first innermost portion 142-1 of the internal channel 142.

[0122] Figures 6 and 7 schematically and in a simplified manner illustrate the speed reducer 100 in a longitudinal cross-sectional view, in a plane including the longitudinal axis X, respectively at the level of the second and last stage E2 and at the level of the first stage EL

[0123] In these figures, the mounting of satellites 130-2 and 130-1 respectively on the satellite carrier 140 is shown in more detail.

[0124] As can be seen in [Fig.6], the satellites 130-2 of the second stage E2, and more generally of the last stage for which n=N, are mounted on the satellite carrier 140 by means of a shaft-bearing mount of a first type.

[0125] The satellite carrier 140 includes a first bearing shaft 151, mounted on the satellite carrier 140, and a pair of first bearings 152 mounted in the satellites 130-2 and on the first bearing shaft 151.

[0126] In particular, the first bearings 152 are rolling bearings, for example ball or roller bearings.

[0127] The satellite 130-2, which here comprises a first toothing 131 which has two tracks 131-1 and 131-2 on either side of the single track of the second toothing 132, includes housings 133-1 and 133-2 which are located respectively under runways 131-1 and 131-2, and which accommodate the first 152 levels. Satellite 130-2 also includes a through opening 134 connecting housings 133-1 and 133-2 and configured to be crossed by the first 151 level axis.

[0128] The first bearings 152 may include an inner bearing ring, which is mounted on the first bearing shaft 151, and an outer bearing ring, which is mounted in the housings 133-1 and 133-2 respectively. The first bearings 152 may also be without an outer bearing ring, the housings 133-1 and 133-2 respectively being bored to form raceways, and the bearing bodies of the first bearings 152 running directly on these raceways.

[0129] The first bearing shaft 151 comprises a first portion 153 having a first diameter and a second portion 154 having a second diameter greater than the first diameter, as well as a shoulder 155 between portions 153 and 154.

[0130] The first portion 153 is here substantially longer than the second portion 154, the latter being able to be substantially longer than the thickness of a wall of the satellite carrier while the first portion 153 is substantially longer than the thickness of satellite 130-2.

[0131] The first bearing shaft 151 also has an end collar 157, which terminates the second portion 154 and has a diameter greater than the second diameter.

[0132] The first bearings 152 are mounted on the first portion 153, and the first bearing 152 closest to the shoulder 155 is abutted against it.

[0133] At least one of the first bearings 152, and here the first bearing 152 closest to the shoulder 155, includes a portion of spacer 156 which extends axially from this first bearing 152. The portion of spacer 156 has an inner diameter greater than the diameter of the first bearing axis 151 and preferably substantially equal to the inner diameter of the first bearing 152, as well as an outer diameter less than the diameter of the through opening 134.

[0134] The portion of spacer 156 comes into butt with the other of the first bearings 152, here the first bearing 152 furthest from the shoulder 155.

[0135] The satellite carrier 140 has a first mounting opening 145 for the stage E2, the diameter of which corresponds to the diameter of the first portion 153, and a second mounting opening 146 for the stage E2, the diameter of which corresponds to the diameter of the second portion 154. In other words, the diameter of the second mounting opening 146 for the stage E2 is larger than that of the first opening mounting 145 of stage E2. The diameter of the second mounting opening 146 is in particular smaller than the diameter of the collar 157.

[0136] The first bearing shaft 151 is mounted in the satellite carrier 140 with one end of its first portion 153 which is mounted in the first mounting opening 145 of the stage E2, and its second portion 154 which is mounted in the second mounting opening 146 of the stage E2, and the collar 157 which is supported on an external face of the wall of the satellite carrier s.

[0137] The shoulder 155 is abutted against a first of the first bearings 152, comprising the portion of spacer 156, which passes through the satellite 130-2 and is itself abutted against a second of the first bearing 152, which in turn is supported against an internal face of the wall of the satellite carrier.

[0138] In other words, the first bearings 152 are held in position by the contact made by the wall of the satellite carrier, the first bearing axis 151, a first of the first bearings 152, a second of the first bearings 152, and again the wall of the satellite, in that order.

[0139] The satellite 130-2 is thus mounted in a floating mount in the satellite carrier 140 by means of the first bearings 152 housed in the housings 133-1 and 133-2.

[0140] Reference is now made to [Fig.7], on which are represented the satellites 130-1 of the first stage El, and more generally of any nth stage for n from 1 to Nl, and which are mounted on the satellite carrier 140 by means of a shaft-bearing mounting of a second type.

[0141] The satellite carrier 140 includes a second bearing shaft 161, mounted on the satellite carrier 140, and a pair of second bearings 162 mounted in the satellites 130-1 and on the second bearing shaft 161.

[0142] In particular, the second bearings 162 are rolling bearings, for example ball or roller bearings.

[0143] The satellite 130-1, which here includes a second toothing 132 which has two tracks 132-1 and 132-2 on either side of the single track of the first toothing 131, includes a through opening 135 called a mounting opening, which is configured to accommodate the second bearings 162 and to be traversed by the second bearing shaft 161.

[0144] The second bearings 162 may include an inner bearing ring, which is mounted on the second bearing shaft 161 or formed directly on it, and an outer bearing ring, which is mounted in the through opening 135. The second bearings 162 may also be without an outer bearing ring, the through opening 135 then being at least partly bored to form raceways, and the bearing bodies of the second bearings 162 moving directly on these raceways.

[0145] Preferably, the second bearings 162 and the second bearing shaft 161 are monobloc and together form a bearing block.

[0146] The second bearing shaft 161 includes a central portion 163 having a first diameter, and on which the second bearings 162 are mounted or formed. The second bearing shaft 161 further includes on the one hand a first mounting portion 164 having a second diameter greater than the first diameter, and on the other hand a second mounting portion 165 having a third diameter greater than the first diameter and the second diameter, the second mounting portion 165 being opposite the first mounting portion 164 on the second bearing shaft 161.

[0147] The third diameter of the second mounting portion 165 is also substantially greater than the diameter of the through opening 135 of the satellite 130-1, while the second diameter of the first mounting portion 164 is substantially less than the diameter of the through opening 135 of the satellite 130-1, so that the bearing block can be introduced into the through opening 135 by the first mounting portion 164.

[0148] The central portion 163 is here substantially longer than the first mounting portion 164 and the second mounting portion 165, the latter being in particular able to be substantially as long as the thickness of a wall of the satellite carrier, while the central portion 163 is substantially as long as the thickness of the satellite 130-1.

[0149] The satellite carrier 140 has a first mounting opening 147 for the El stage, the diameter of which corresponds to the diameter of the first mounting portion 164, and a second mounting opening 148 for the El stage, the diameter of which corresponds to the diameter of the second mounting portion 165. In other words, the diameter of the second mounting opening 148 for the El stage is larger than that of the first mounting opening 147 for the El stage.

[0150] The second bearing shaft 161 is mounted in the planet carrier 140 with its first mounting portion 164 which is mounted in the first mounting opening 147 of the EL stage, and its second mounting portion 165 which is mounted in the second mounting opening 148 of the EL stage

[0151] The bearing block, comprising the second bearing shaft 161 and the second bearings 162, is fixedly mounted in the satellite carrier, and the satellite 130-1 is floatingly mounted in the bearing block via the second bearings 162 housed in the through opening 135.

[0152] It should be specified that, of course, the characteristics described above with reference to Figures 6 and 7 for a top-stage satellite and a first-stage satellite can be applied to the satellite carrier for all top-stage and first-stage satellites, as well as for intermediate-stage satellites, where appropriate.

[0153] The operation of the speed reducer 100 will now be described in more detail in particular with reference to [Fig.8], which represents a block diagram of a method 200 for mounting the speed reducer 100, comprising the steps described below.

[0154] Prior to its assembly, the speed reducer 100 can be made available with the solar 110, the ring 120, the satellites 130 and the satellite carrier 140 which are detached from each other.

[0155] The method 200 includes a step 210 of introducing all the satellites 130 into the satellite carrier 140. During this step, the satellites 130 of each gear series are introduced through the radial mounting opening 141 of the series, in the order of the first stage satellite, for which n=l, up to the last stage satellite, for which n=N.

[0156] In the example illustrated in figures 4 and 5, the satellite 130-1 and then the satellite 130-2 of each series of gear is introduced through the radial opening 141.

[0157] The satellites 130 of each series of gear are moved in their internal channel 142 until they respectively reach their mounting location.

[0158] In the example illustrated in Figures 4 and 5, satellite 130-1 is moved in the second section 142-2 and then in the first section 142-1 of the internal channel 142 until its center reaches the mounting position ML. Satellite 130-2 is moved in the second section 142-2 until its center reaches the mounting position M2. In other words, the satellites 130 are moved overall towards the interior of the satellite carrier 140 in the direction of the solar 110 and away from the radial opening 141.

[0159] The head circle of the first tooth 131 of the satellite 130-2 is then circumscribed inside the head circle of the internal tooth of the ring 120, and the speed reducer 100 is in its mounting configuration.

[0160] Prior to the introduction step 210, the method 200 may include a pre-assembly step 205 of the satellites 130.

[0161] During this step 205, the satellites of the top stage in particular, here the satellites 130-2 of the second stage E2, can be fitted with the first bearings 152, which are introduced into the respective housings 133-1 and 133-2.

[0162] The method 200 then includes a step 220 of positioning the satellite carrier 140, equipped with the satellites 130 but which are not yet mounted on their respective nominal locations, in the ring 120. This step can be carried out effortlessly by simply axially inserting the satellite carrier 140 into the ring 120.

[0163] The method 200 then includes a step 230 of moving the satellites 130 to their nominal locations, and mounting the satellites 130 at these locations.

[0164] The satellites 130 of each series of gear are moved in their internal channel 142 until they respectively reach their nominal location, this movement being an inverse movement to that of the insertion step 210.

[0165] In the example illustrated in Figures 4 and 5, satellite 130-1 is moved in the first portion 142-1 of the internal corridor 142 until its center reaches the nominal position NI. Satellite 130-2 is moved in the second portion 142-2 until its center reaches the nominal position N2. In other words, the satellites 130 are moved overall towards the radial aperture 141 and away from the solar array 110.

[0166] The head circle of the first tooth 131 of the satellite 130-2 then protrudes radially from the head circle of the internal tooth of the ring 120, or even from the ring 120 entirely, the second tooth 132 of the satellite 130-2 being in contact with the tooth of the ring 120, and the speed reducer 100 is in its operating configuration.

[0167] Step 230 includes mounting the satellites 130 in their nominal locations, including inserting the bearing blocks into the satellites of the nth stages, n from 1 to Nl, and inserting the first bearing shafts 151 into the satellites of the last stage, in which the first bearings 152 are pre-mounted.

[0168] In the illustrated example, as seen in [Fig.6], the first bearing shaft 151 is inserted through the second mounting opening 146 of the E2 stage, then through the through opening 134 of the satellite 130-2 as well as through the inner rings of the first bearings 152, and finally the first mounting opening 145 of the E2 stage.

[0169] In the illustrated example, as seen in [Fig. 7], the second bearing shaft 161 equipped with the second bearings 162 is inserted through the second mounting opening 148 of the EL stage, then through the through-hole 135 of the satellite 130-1, and finally through the first mounting opening 147 of the EL stage.

[0170] At the end of step 230, the satellites 130 and the ring 120 thus mesh with each other.

[0171] The solar 110 can then be mounted in the satellite carrier 140, then the speed reducer can be mounted on the low pressure shaft 7, or the solar 110 is first mounted on the low pressure shaft 7 and then the satellite carrier 140 is mounted on the solar 110.

[0172] Alternatively, the solar 110 can also be introduced into the satellite carrier 140 upstream of the insertion step 210.

[0173] The speed reducer 100, equipped with a planet carrier 140 as described above, and the mounting method 200, make it possible to obtain a particularly compact and easy-to-mount speed reduction solution.

[0174] In particular when the satellites 130 have a first toothing 131 and a second toothing 132, the arrangement of the satellites 130 can be particularly compact, especially with a toothing of the satellites of the last stage which protrudes from the crown, while allowing particularly large reduction ratios.

[0175] The speed reducer 100 also allows for very simple mounting thanks to its mounting configuration which it can adopt, and the operating configuration which it can then adopt by simply moving the satellites 130 in the internal corridors 142.

[0176] In particular, the speed reducer 100 allows its constituent elements, in particular the ring 120, the satellites 130 and the satellite carrier 140, to be made in one piece, while allowing easy assembly of these elements.

[0177] A single-piece design is particularly advantageous when the speed reducer 100 is intended to transform large rotational speeds and / or large torques, as is the case in the drive of a blower by a turbine in a turbomachine.

[0178] The invention also relates to a turbomachine comprising a speed reducer 100, comprising for example two stages as described above, for example connected to the fan 10 in a planetary configuration, i.e. by its ring 120. Such a turbomachine can for example equip an aircraft, preferably a fixed-wing aircraft, such as an airplane (not shown), in particular a commercial airliner.

[0179] The invention also relates to a set of turbomachines which includes a first turbomachine having a speed reducer as described above with an even number of stages, and a second turbomachine, having a speed reducer as described above with an odd number of stages.

[0180] As a result, the blowers of each of the turbomachines in the turbomachinery set rotate in opposite directions, while their turbines rotate in the same direction.

[0181] Since the speed reducers of each of the turbomachines have the same type of connection, here planetary but also epicyclic or differential, it is possible to integrate either of the reducers in the same way into otherwise identical turbomachines. Furthermore, as described above, the speed reducer 100 according to the invention can It must be designed in a particularly compact manner, especially with two satellite stages, and have the same footprint as the speed reducer of the other turbomachine, which, for example, has only one satellite stage. This results in easier integration into the turbomachine.

[0182] Such a set of turbomachinery can advantageously be used in an aircraft, in particular a fixed-wing aircraft comprising a pair of wings, such as an airplane (not shown), in particular an airliner type.

[0183] Each of the aircraft's wings, which are opposite each other with respect to the aircraft fuselage, incorporates one of the turbomachines from the turbomachinery set. Thus, the fans located on either side of the aircraft fuselage rotate in opposite directions. This makes it possible to reduce or even eliminate the moments of force exerted on the aircraft by the reaction forces to the rotation of the fans.

[0184] Preferably, the turbomachines in the turbomachinery set have fans that are unshod, i.e. the turbomachines are of the propfan or openfan type (according to English terminology).

[0185] In particular, the aircraft is of the twin-engine type, but can also be of the four-engine type and include two sets of turbomachinery, with one pair of turbomachinery per wing with fans rotating in the same direction, and in the opposite direction the fans of the other pair.

[0186] It is more generally recalled that the invention is not limited to the examples described and illustrated.

[0187] According to other embodiments not illustrated: - Satellite stages include different numbers of satellites. - The meshing between the solar system, the satellites and the corona can be ensured by contact, by friction, or by magnetic field, rather than by gearing. - The teeth of the solar stellium, and / or the satellites and / or the crown can be of the straight tooth type, helical tooth type, or chevron tooth type - Each of the satellites of the A-th stage can include a bearing axis and a number of bearings other than two, for example a number from 1 to 6. - Similarly, each of the satellites of the nth stages, n ranging from 1 to Nl, can include a bearing block comprising a bearing axis and a number of bearings different from two, for example a number ranging from 1 to 6. - For example, the number of stages per satellite is equal to 1, and the stage of each satellite is preferably of the hydrodynamic stage type.

Claims

1. Demands Speed ​​reducer (100) for driving a turbomachine fan, the speed reducer comprising a solar element (110), a ring gear (120), a plurality of satellites (130), and a satellite carrier (140) supporting said satellites, the solar element (110) being configured to be mechanically connected to a turbomachine turbine to be driven in rotation by it, and at least one of the ring gear (120) or the satellite carrier (140) being configured to be mechanically connected to a turbomachine fan to drive it in rotation, the speed reducer being characterized in that: the satellites (130) are arranged according to N stages of satellites arranged between the solar (110) and the corona (120), N being an integer, each nth stage, n going from 1 to N, comprising at least two satellites; in that the speed reducer is configured to adopt an operating configuration in which the satellites (130) are each mounted at a determined nominal location, in which a first of said stages, for which n=l, presents each of its satellites which mesh with the solar (110) and a last of said stages, for which n=N, presents each of its satellites which mesh with the ring (120), and, for the satellites of an nth and an n+7th directly consecutive stage, n going from 1 to N-1, each satellite of the nth stage meshes with a satellite of the n+7th stage, so as to form a plurality of gear sets between the solar and the ring; in that the planet carrier comprises, for each gear set, a radial opening (141) configured to permit the radial introduction of each of the gear set's planets into the planet carrier, and an internal channel (142) communicating with the radial opening (141) and extending from the radial opening through the nominal locations of each of the gear set's planets, to an internal area (143) of the planet carrier situated beyond the nominal location of the first-stage planet, for which n=l; and in that the speed reducer is further configured to adopt a mounting configuration in which the planets (130) are introduced into the planet carrier and positioned in the internal corridors (142) at mounting locations situated beyond their nominal locations, so that the satellites of the last stage, for which n=N, have the head circle of their teeth which is circumscribed within the head circle of the ring (120); whereby the satellite carrier (140) equipped with the satellites (130) can be introduced into the ring (120) to then pass into its operating configuration by moving the satellites (130) to their nominal locations.

2. Speed ​​reducer (100) according to claim 1, wherein the internal channel (142) of each of the gear series has N consecutive substantially straight portions arranged at an angle to each other, each nth portion of the internal channel, n from 1 to N, being configured to allow a displacement of a satellite of the nth stage of the gear series at least between its nominal location and its mounting location.

3. Speed ​​reducer (100) according to any one of claims 1 or 2, wherein the internal channels (142) of each of the gear sets communicate with a central cavity of the satellite carrier configured to accommodate the solar (110), and / or the internal channels (142) of each of the gear sets communicate directly with each other.

4. Speed ​​reducer (100) according to any one of claims 1 to 3, wherein the ring (120), and / or the solar (110), and / or the satellites (130), and / or the satellite carrier (140), are monobloc.

5. Speed ​​reducer (100) according to any one of claims 1 to 4, wherein the satellites (130) each comprise a first tooth (131) and a second tooth (132), said teeth being coaxial and distinct from each other, each of the meshes between two satellites of directly consecutive stages being formed by the first tooth of a satellite belonging to a first of said stages and the second tooth of a satellite belonging to a second of said stages, the first tooth of the satellites of the last stage, for which n=N, having a nominal circle radially exceeding the nominal circle of the ring in the operating configuration of the speed reducer.

6. Speed ​​reducer (100) according to claim 5, wherein the solar (110) is configured to be driven in rotation by a low pressure turbomachine shaft, and wherein the first toothing (131) of each of the satellites (130) is a driven toothing and the second toothing (132) of each of the satellites (130) is a driving toothing.

7. Speed ​​reducer (100) according to any one of claims 5 or 6, wherein the planet carrier (140) comprises, for each of the satellites of the AMth stage, a bearing shaft (151) and a pair of bearings (152), for mounting each of the satellites of the Nth stage on the planet carrier, said bearings being mounted under the first toothing (131) of each of the satellites of the AMth stage.

8. Speed ​​reducer (100) according to claim 7, wherein at least one of said bearings (152) has an axially extending spacer portion (156), said bearing shaft (151) having a first portion (153) having a first diameter and a second portion (154) having a second diameter larger than the first diameter, and a shoulder (155) between said first and second portions, the bearing shaft (151) being configured to be mounted by its first portion (153) and its second portion (154) in corresponding mounting openings of the planet carrier, said bearings (152) being configured to be mounted on the first portion (153) of the bearing shaft with one of the bearings abutting said shoulder (155) and with the bearings contacting each other via of said portion of spacer (156).

9. Speed ​​reducer (100) according to any one of claims 1 to 8, wherein the satellite carrier (140) comprises, for each of the satellites of the nth stages, n from 1 to N1, a bearing block comprising a bearing shaft (161) and a pair of bearings (162), the bearing block being configured to be mounted in a mounting opening of the satellite.

10. Speed ​​reducer (100) according to claim 9, wherein the bearing block is a single piece, the bearing shaft (161) comprising a first mounting portion (164) and a second mounting portion (165) and the bearings (162) being arranged between said first and second portions, the bearing shaft (161) being configured to be mounted by its first mounting portion (164) and its second mounting portion (165) in corresponding mounting openings of the satellite carrier, and the first mounting portion (164) having a first diameter less than a diameter of the satellite mounting opening, and the second mounting portion (165) having a second diameter greater than the first diameter and greater than the diameter of the satellite mounting opening.

11. Turbomachine (1), preferably a turbojet with an unfaired fan, comprising a turbine, a fan (10) and a speed reducer (100) according to any one of claims 1 to 10, the speed reducer being connected at the inlet to the turbine via its solar (110), so as to be able to be driven into rotation by the turbine, and connected at the outlet to the fan (10) via at least one of its ring (120) and its planet carrier (140), so as to be able to drive into rotation the fan (10).

12. Fixed-wing aircraft comprising a turbomachine (1) according to claim 11.

13. A method (200) for mounting a speed reducer (100) according to any one of claims 1 to 10, comprising: - a step (210) of introducing all the planets of each gear set into the planet carrier (140) through the radial opening (141) of each gear set, such that the planet carrier is in its mounting configuration; - a step (220) of positioning the planet carrier (140) in the ring gear (120); - a step (230) of moving and mounting the planets (130) to their nominal positions, such that the planet carrier is in its operating configuration.

14. A method (200) of assembly according to claim 13, for mounting a speed reducer (100) according to claims 7 or 8 and 9 or 10, further comprising: - a step (205) of pre-mounting the bearings (152) in the satellites at least of the last stage, for which n=N, upstream of the introduction step (210) and ; in which the displacement and mounting step (230) comprises the insertion of the bearings (162) into the satellites of the nth stages, "from 7 to N1, as well as the insertion of the bearing shafts (161) in each of the satellites and in the corresponding mounting openings of the satellite carrier.

15. Planet carrier (140) configured to be mounted in a speed reducer (100) according to any one of claims 1 to 10, comprising, for each gear set, a radial opening (141) configured to permit radial introduction of each of the gear set satellites into the planet carrier, and an internal channel (142) communicating with the radial opening (141) and extending from the radial opening through the nominal locations of each of the gear set satellites, to an internal area (143) of the planet carrier located beyond the nominal location of the satellite belonging to the first stage, for which n=l.

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