AIRCRAFT TURBOMACHINE MECHANICAL REDUCTION GEAR

Abstract

The invention relates to a mechanical gearbox (100) for a turbomachine comprising: - a pinion (110) for drive by an input shaft, - a wheel (120) having a main axis (C2) parallel to a main axis (C1) of the pinion, and configured to mesh with the pinion (110), and - a gear train (130) configured to be driven by the wheel (120) and comprising a sun gear (132), a ring gear (134) radially around the sun gear, planet gears (136), and a planet carrier mounted to rotate flexibly relative to the ring gear and the sun gear, wherein the ring gear, the sun gear, and the planet carrier are substantially coaxial with the main axis (C2) of the wheel (120), and the planet carrier (138) comprises a coupling portion with an output shaft. The sun gear (132) is configured to be rotated by the wheel (120), which comprises a Rim (1222) housing the crown (134). Figure for the abbreviation: Figure 4

Description

Title of the invention: MECHANICAL REDUCER FOR AIRCRAFT TURBOMACHINE technical field

[0001] The present invention relates to the field of mechanical reducers for turbomachinery, in particular aircraft. Previous technique

[0002] The role of a mechanical reducer is to modify the speed and torque ratio between the input shaft and the output shaft of a mechanical system.

[0003] New generations of turbofan engines, particularly those with a high bypass ratio, include a mechanical gearbox to drive the shaft of a fan. Typically, the purpose of the gearbox is to transform the high rotational speed of the power turbine shaft into a slower rotational speed for the fan-driving shaft.

[0004] Such a reduction gear comprises a central pinion, called the sun gear, a ring gear, and pinions called planet gears, which mesh between the sun gear and the ring gear. The planet gears are held by a frame called a planet carrier. The sun gear, ring gear, and planet carrier are planetary gears because their axes of revolution coincide with the longitudinal axis of the turbomachine. The planet gears each have a different axis of revolution and are equally spaced on the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis of the turbomachine.

[0005] Several gearbox architectures exist. In the state of the art of turbofan engines, gearboxes are of the planetary or epicyclic type. In other similar applications, there are so-called differential or "compound" architectures.

[0006] - On a planetary gearbox, the planet carrier is fixed and the ring gear constitutes the output shaft of the device which rotates in the opposite direction to the solar.

[0007] - On an epicyclic reducer, the ring gear is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar panel.

[0008] - On a differential reducer, no element is fixed for rotation. The ring rotates in the opposite direction to the solar panel and the satellite carrier.

[0009] Reducers can be composed of one or more meshing stages. This meshing is achieved in various ways such as by contact, by friction or by magnetic fields.

[0010] In this application, the term "stage" or "toothing" refers to a series of teeth that mesh with a series of complementary teeth. A toothing can be internal or external.

[0011] A satellite may comprise one or two gear stages. A single-stage satellite comprises teeth that may be straight, helical, or chevron-shaped, and whose teeth are located on the same diameter. These teeth cooperate with both the sun gear and the crown gear.

[0012] A two-stage satellite comprises two sets of teeth or two series of teeth which are located on different diameters. A first set of teeth cooperates with the sun gear and a second set of teeth cooperates with the crown gear.

[0013] Furthermore, each satellite is centered and guided in rotation around an axis by a bearing which is carried by the satellite carrier.

[0014] Such a reducer allows for large propellers which allow for more air to be moved and turbines which rotate quickly and are therefore more efficient.

[0015] However, the presence of a reduction gear in an aircraft engine adds a relatively massive assembly with a significant radial and axial footprint.

[0016] However, compactness and weight are determining factors in the design of an aircraft engine.

[0017] In order to obtain a sufficient reduction ratio of about 9, reducers also called gearboxes are often composed of at least two reduction stages.

[0018] These reduction stages can be of the pinion / wheel, planetary and / or epicyclic type.

[0019] Fig. 1 schematically represents an example of a conventional two-stage mechanical reducer mounted on a turbomachine comprising, in a conventional manner, a blower S.

[0020] According to this example, the first reduction stage RI consists of a pinion 1 IA driven by an input shaft such as a low-pressure turbine shaft 30A of the turbomachine T and a wheel 12A meshed with the pinion. The second reduction stage R2 here consists of a gear train 13A meshing with the wheel 12A of the first reduction stage, for example of the epicyclic or planetary type. The gear train 13A conventionally comprises a sun gear 132A driven by coupling with the wheel of the first reduction stage, a ring gear 134A, planet gears 136A meshing with the ring gear and the sun gear, and a planet carrier 138A coupled with a propeller drive shaft in the case of a turboprop or with a fan wheel drive shaft 40A in the case of a turbomachine.

[0021] The presence of a first reduction stage of the pinion / wheel type implies a shift, called "offset" in English, denoted D in [Fig. 1], between the input shaft and the output shaft of the gearbox. This offset D is the distance between the axis of the input shaft, for example, the shaft of a low-pressure turbine, and the axis of the output shaft, for example, the drive shaft of a propeller or fan. This gap or offset between the two axes allows the propeller, or fan, to be raised closer to the wing plane and to blow air both above and below the aircraft wing.

[0022] In general, the addition of several reduction stages leads to an increase in axial dimensions, which affects the length of the motor and / or the internal arrangement of the motor and its mass

[0023] The objective of the present invention is therefore to overcome these drawbacks. Summary of the invention

[0024] To this end, the invention relates to a mechanical reducer for a turbomachine comprising: - a pinion having a first main axis and intended to be driven by an input shaft, - a wheel having a second main axis parallel to the first main axis, the wheel being configured to mesh with the pinion, and - a gear train configured to be driven by the wheel and comprising a sun gear having a central axis coaxial with the second main axis, a ring gear arranged radially around the sun gear, satellites configured to mesh with the ring gear and with the sun gear, and a satellite carrier mounted movable in rotation relative to the ring gear and the sun gear and supporting the satellites, in which the ring gear, the sun gear and the satellite carrier are substantially coaxial and the satellite carrier has a coupling part intended to be coupled in rotation with an output shaft. According to the invention, the solar panel is configured to be driven in rotation around the central axis by the wheel, and the wheel has a rim housing the crown of the gear train.

[0025] The invention thus proposes a two-stage reduction reducer capable of overcoming the aforementioned disadvantages.

[0026] To this end, the invention proposes a two-stage reduction reducer in which an epicyclic reducer is arranged inside the ring of a wheel.

[0027] Thus, the second reduction stage is nested in the first stage of the reducer, making it possible to reduce and optimize the radial and axial dimensions of the reducer compared to the prior art.

[0028] Advantageously, this reduction in axial bulk has an impact on the length of the motor and / or on the internal arrangement of the motor.

[0029] Indeed, the invention makes it possible to integrate accessories on the reducer without increasing the radial size of the motor.

[0030] Such a reducer according to the invention thus advantageously presents a high compactness.

[0031] The reducer according to the invention may comprise one or more of the following features, taken individually or in combination with each other in all technically possible combinations: - the wheel is configured to mesh directly with the pinion; - the mechanical reducer includes a reversing pinion having a third main axis substantially parallel to the first main axis, the reversing pinion being configured to mesh with the pinion and with the wheel; - the gear train is an epicyclic gear train; - the wheel has a flange from which the wheel rim extends in a first direction and a first shaft extending from the flange in a second direction opposite to the first direction; - the satellite carrier includes a second shaft extending axially along the second main axis between an upstream end and a downstream end, the second shaft being substantially coaxial with the first shaft, a downstream portion of the second shaft extends inside the first shaft of the wheel so that the downstream end of the second shaft emerges from the first shaft of the wheel; - the mechanical reducer includes at least two bearings configured to support and guide the planet carrier, the two bearings each being arranged on the second shaft of the planet carrier respectively at the upstream end and at the downstream end; - the wheel includes a toothed wheel configured to be mechanically connected to at least one piece of equipment of the turbomachine.

[0032] The invention also relates to a turbomachine, in particular an aircraft turbomachine, comprising a mechanical reducer according to the invention and as described above.

[0033] The invention also relates to an aircraft comprising such a turbomachine according to the invention and as described above or a mechanical reducer according to the invention and as described above. Brief description of the drawings

[0034] The present invention will be better understood and other details, features and advantages of the present invention will become more apparent upon reading the description of a non-limiting example that follows, with reference to the accompanying drawings in which: - Fig. 1, already described, represents a schematic axial cross-sectional view of a reducer according to the prior art; - [Fig.2] is a schematic axial cross-sectional view of a turbomachine to which the invention applies; - [Fig.3] is a schematic axial cross-sectional view of a first embodiment of a reducer according to the invention; - Figure 4 is a schematic cross-sectional view of the reducer in Figure 3; - Figure 5 is a schematic axial cross-sectional view of a second embodiment of a reducer according to the invention; and - [Fig.6] is a schematic cross-sectional view of the reducer of [Fig.5]; Elements having the same functions in the different implementations have the same references in the figures.

[0035] In the figures, the scales and proportions are not strictly respected for the purposes of illustration and clarity.

[0036] Furthermore, in the description and claims, the terminology axial, radial and transverse will be adopted without limitation with reference to the trihedron A, R, T indicated in the figures, the axial axis A being parallel to the longitudinal axis of the reducer according to the invention.

[0037] Thus, the terms "axial" and "axially" are defined with respect to the axial axis A, which is parallel to the longitudinal axis C of the reducer. The terms "radial" and "radially" are defined with respect to the axis R, which is perpendicular to the longitudinal axis C of the reducer.

[0038] In the description, and unless otherwise stated, the terms "internal" and "external" are used by way of non-limiting reference to the radial distance from the longitudinal axis around which the lubrication chamber extends, the term "internal" defining an area radially closer to the longitudinal axis of the reducer, as opposed to the term "external". Description of the implementation methods

[0039] The present invention relates to a speed reducer intended to equip in particular a turboprop or a turbomachine of an aircraft.

[0040] Figure 2 illustrates such a turbomachine 10 which conventionally comprises a A blower S, a low-pressure compressor 12, a high-pressure compressor 13, an annular combustion chamber 14, a high-pressure turbine 15, a low-pressure turbine 16, and an exhaust nozzle 17. The high-pressure compressor 13 and the high-pressure turbine 15 are connected by a high-pressure shaft 20 and together form a high-pressure (HP) unit. The low-pressure compressor 12 and the low-pressure turbine 16 are connected by a low-pressure shaft 30 and together form a low-pressure (LP) unit.

[0041] The blower S is driven by a blower shaft 40 which is driven by the low pressure shaft 30 by means of a mechanical reducer 100 according to the invention.

[0042] The mechanical reducer 100 is positioned in the upstream part of the turbomachine. A fixed structure schematically comprising, here, an upstream part 50a and a downstream part 50b which make up the motor or stator housing 50, is arranged to form an enclosure E surrounding the reducer 100. This enclosure E is closed upstream by seals at the level of a bearing allowing the passage of the blower shaft 40, and downstream by seals at the level of the passage of the low-pressure shaft 30.

[0043] Figures 3 and 4 schematically represent a first embodiment of a mechanical reducer 100 according to the invention. [Fig. 3] is a schematic axial cross-sectional view of the mechanical reducer according to the invention, while [Fig. 4] is a schematic transverse cross-sectional view of the mechanical reducer in the BB plane of [Fig. 3]. According to this first embodiment, the mechanical reducer 100 according to the invention is of the two-stage reduction type.

[0044] For this purpose, the mechanical reducer 100 according to the invention comprises a pinion 110, a wheel 120 and a gear train 130.

[0045] The pinion 110 and the wheel 120 form a first reduction stage of the reducer. The gear train 130 forms a second reduction stage of the reducer.

[0046] The pinion 110 has a first main axis Cl intended to be parallel to, and even coincide with, the longitudinal axis X of the turbomachine that the reducer equips.

[0047] The pinion 110 is intended to be driven by an input shaft (not visible), for example by the low-pressure shaft 30 of the turbomachine.

[0048] For this purpose, the pinion 110 of the first stage of the reducer 100 is connected, at its input, to the input shaft, for example via splines. The pinion 110 has first external splines (not shown) intended to mesh with internal splines formed on the input shaft, for example the low-pressure turbine shaft of the turbomachine.

[0049] Preferably, the first external splines of the pinion 110 meshing with the input shaft are straight or herringbone.

[0050] The pinion 110 is supported by two bearings PI and P2.

[0051] The pinion 110 has two opposite ends: an upstream end 110a and a downstream end 110b.

[0052] Preferably, the two bearings PI, P2 of the pinion 110 are each arranged at one of the ends 110a, 110b of the pinion.

[0053] For example, the two bearings PI, P2 are plain bearings or roller or ball bearings.

[0054] The wheel 120 has a main axis, called the second main axis C2, parallel to the first main axis Cl of the pinion 110.

[0055] The wheel 120 comprises a tubular part forming a first shaft 121 extending axially along the second main axis C2 between a first end, called the upstream end 121a, and a second end, called the downstream end 121b, opposite the upstream end 121a. In the figure, the second main axis C2 is parallel to the axial direction A.

[0056] The wheel 120 further comprises an annular part 122 extending radially outwards from the upstream end 121a of the tubular part forming the first shaft 121.

[0057] More specifically, the annular portion 122 comprises a flange 1221 and a rim 1222. The flange 1221 extends radially outwards from the upstream end 121a of the first shaft 121. Furthermore, the rim 1222 extends from the flange 1221 in a direction parallel to the axial direction A such that the flange 1221 is arranged between the rim 1222 and the first shaft 121. In other words, the rim 1222 of the wheel 120 extends from the flange 1221 in a first direction, in particular axially upstream in the example shown, while the tubular portion 121 extends from the flange in a second direction opposite to the first direction, in particular axially downstream in the example illustrated.

[0058] The wheel 120 is configured to mesh with the pinion 110. More precisely, the wheel 120 is configured to mesh directly with the pinion 110 according to this first embodiment.

[0059] For this purpose, the pinion 110 of the first stage of the reducer 100 has external splines, called second external splines 114, intended to cooperate by meshing with complementary external splines 124 provided on the wheel 120, and in particular on an external surface 1222A of the rim 1222.

[0060] The second external splines 114 of the pinion 110 are arranged on an external surface of the pinion 110 between its upstream end 121a and its downstream end 121b.

[0061] Preferably, the second external splines 114 of the pinion 110 engaging the wheel 120 and the external splines 124 of the wheel 120 are straight or herringbone.

[0062] The wheel 120 is supported by two bearings P3 and P4. Preferably, the two bearings P3, P4 are roller or ball bearings. Advantageously, the two bearings P3, P4 of the wheel 120 are arranged on the tubular portion forming the first shaft 121 of the wheel 120. Preferably, the two bearings P3, P4 of the wheel 120 are each arranged at one of the ends 121a, 121b of the tubular portion forming the first shaft 121 of the wheel 120.

[0063] Advantageously, the wheel 120 of the first reduction stage of the mechanical reducer 100 may further comprise a toothed wheel 125 configured to be connected mechanically to one or more pieces of equipment of the turbomachine. For example, the equipment may be a propeller or fan brake, a pump, a generator, a turning motor, i.e. a low speed motor useful for maintenance operations.

[0064] Preferably, the gear 125 extends radially outwards from the tubular part forming the first shaft 121 of the gear 120.

[0065] Advantageously, the toothed wheel 125 is arranged between the two bearings P3, P4 supporting the wheel 120.

[0066] The gear train 130 is configured to be driven by the wheel 120.

[0067] The gear train 130 comprises: - an internal planetary, also called solar 132, - an outer planetary gear, also called the 134 crown, - 136 satellites, and - a satellite carrier 138.

[0068] The gear train 130 is of the epicyclic type. Thus, the planet carrier 138 and the sun gear 132 are mobile in rotation while the ring gear 134 of the reducer is fixed in the frame of reference of the turbomachine.

[0069] The solar 132 has a central axis coaxial with the second main axis C2 of the wheel 120. In other words, the second main axis C2 is a rotation axis of the solar 132.

[0070] The solar 132 comprises a tubular part 1321 extending axially along the second principal axis C2 between a first end, called upstream end 1321a, and a second end, called downstream end 1321b.

[0071] The solar 132 further comprises an annular part 1322 extending radially outwards from the upstream end 1321a of the tubular part 1321.

[0072] The annular part 1322 of the solar 132 extends into the annular part 122 of the wheel 120.

[0073] In addition, the tubular part 1321 extends axially inside the tubular part forming the first shaft 121 of the wheel 120.

[0074] Furthermore, the solar element 132 is mechanically connected to the wheel 120. More precisely, the tubular portion 1321 of the solar element 132 is mechanically connected to the tubular portion forming the first shaft 121 of the wheel 120. For example, this mechanical connection is achieved by a splined joint, a weld, or a bolted flange. Thus, the solar element 132 is configured to be driven in rotation about the central axis, coaxial with the second main axis C2, by the wheel 120.

[0075] Furthermore, the solar 132, and more specifically the annular part 1322, has on a radially external surface 1322A a coupling means with the satellites 136. Preferably, the coupling means has a radially external toothing 1323. For example, the radially external teeth are straight teeth, helical teeth, or herringbone teeth. Alternatively, the coupling means may also have radially internal splines.

[0076] The ring 134 is arranged axially around the solar element 132. It has a central axis substantially coaxial with the solar element 132. By "axially around the solar element," it is understood, for the purposes of the invention, that the ring 134 extends radially outward from the solar element 132 and, moreover, the ring 134 and the solar element 132 have substantially the same median plane orthogonal to the central axis of the solar element. This median plane is a plane transverse to the central axis of the solar element and is substantially coaxial with the second principal axis C2.

[0077] The crown 134 has on its radially internal surface 134B a coupling means with the satellites 136. Preferably, the coupling means has radially internal teeth 1341. For example, the radially internal teeth are straight teeth, helical teeth, or herringbone teeth. Alternatively, the coupling means may also have radially internal splines.

[0078] The crown 134 is mechanically linked to a housing not shown of the reducer, for example by a flange.

[0079] According to the invention, the ring gear 134 of the second reduction stage of the mechanical reducer 100 is advantageously integrated into the wheel 120 of the first reduction stage of the mechanical reducer 100. In other words, the ring gear 134 of the gear train 130 is radially internal to the rim 1222 of the wheel 120. That is to say, the ring gear 134 of the gear train 130 has a radially external surface 134A arranged opposite a radially internal surface 1222B of the rim 1222 of the wheel 120. The ring 134 of the gear train 130 is housed radially inside the annular part 122 of the wheel 120 of the first reduction stage and radially outside the annular part 1322 of the sun 132 of the gear train 130. In other words, the ring 134 of the gear train 130 has an outside diameter which is less than an inside diameter of the wheel 120 and in particular of the rim 1222 of the latter.

[0080] In other words, a median plane can be defined for the ring 134, called the "first median plane," which is transverse to the central axis of the sun gear, that is, orthogonal to the central axis of the sun gear, which is substantially coaxial with the second principal axis C2. More precisely, this first median plane passes through the midpoint of the teeth of the ring 134. Similarly, the rim 1222 of the wheel 120 has a median plane called the "second median plane," which is transverse to the second principal axis C2. More precisely, this second median plane passes through the midpoint of the teeth of the wheel 120. The distance, along the axial direction A, between the second median plane and the first median plane median is less than 2.5 times an axial dimension, or total width, of the teeth of wheel 120, and preferably less than half the axial dimension of the teeth of wheel 120.

[0081] The satellites 136 are configured to each mesh simultaneously with the ring gear 134 and the sun gear 132 of the gear train 130. For this purpose, each satellite 136 has a radially external toothing 1361 configured to mesh simultaneously with the radially internal toothing 1341 of the ring gear 134 and the radially external toothing 1323 of the annular part 1322 of the sun gear 132. For example, the radially external toothing 1361 of the satellites is a straight toothing or a helical toothing or a herringbone toothing.

[0082] The satellites 136 are equally distributed over the same diameter around the central axis of the solar 132 coinciding with the second main axis C2 of the wheel 120.

[0083] The number of satellites 136 is generally defined between three and seven for this type of application.

[0084] The set of satellites 136 is held by a chassis called a satellite carrier 138.

[0085] Each satellite 136 rotates around its own axis Ci.

[0086] The planet carrier 138 is mounted to rotate freely relative to the ring 134 and the sun 132 of the gear train 130. The planet carrier 138 supports the set of satellites 136 in such a way that the rotation of the set of satellites 136 causes the planet carrier 138 to rotate around the central axis of the sun 132 which coincides with the second main axis C2 of the wheel 120.

[0087] The satellite carrier 138 includes a tubular part forming a second shaft 1381 extending axially along the second main axis C2 between a first end, called the upstream end 1381a, and a second end, called the downstream end 1381b.

[0088] The planet carrier 138 includes a coupling portion intended to be rotationally coupled with an output shaft. More specifically, the upstream end 1381a of the tubular portion forming the second shaft 1381 of the planet carrier 138 is intended to be mechanically connected to an output shaft, for example, a drive shaft of a propeller or a fan. Preferably, the upstream end 1381a of the second shaft 1381 of the planet carrier 138 has radially external splines, not visible in [Fig. 3], for coupling with the output shaft. Alternatively, the upstream end 1381a of the second shaft 1381 of the planet carrier 138 is intended to be mechanically connected to the output shaft by a bolted flange or a weld.

[0089] The second shaft 1381 is substantially coaxial with the first shaft 121 of the wheel 120.

[0090] The tubular part forming the second shaft 1381 of the satellite carrier 138 includes a downstream portion that extends inside the solar 132 and the wheel 120. More Specifically, the tubular part forming the second shaft 1381 of the satellite carrier 138 passes through the solar 132 and the wheel 120 so that the downstream end 1381b of the tubular part 1381 emerges from the tubular part forming the first shaft 121 of the wheel 120.

[0091] Furthermore, the satellite carrier s 138, and in particular its tubular part forming the second shaft 1381, is supported and guided by three bearings P5, P6 and P7. The three bearings P5, P6 and P7 are arranged on the tubular part forming the second shaft 1381 of the satellite carrier 138.

[0092] Preferably, bearings P5 and P7 are roller bearings or hydrodynamic bearings, while bearing P6 is a thrust ball bearing. The two bearings P5 and P7 of the planet carrier 138 are each arranged at one of the ends 1381a and 1381b of the tubular portion 1381 of the planet carrier 138. They are therefore arranged on either side of the solar array 132 and the wheel 120 in order to optimize the transfer of forces from the propeller or the fan by spacing the supporting bearings apart. The thrust ball bearing P6 is arranged at the upstream end 1381a of the tubular portion 1381 of the planet carrier 138, between bearing P5 and an annular portion 1382 of the planet carrier 138.

[0093] The annular part 1382 of the satellite carrier 138 extends radially outwards from an external surface 1383 of the tubular part 1381.

[0094] The satellite carrier 138 comprises shafts 1384 extending axially from the radially external periphery of the annular part 1382 downstream.

[0095] Each satellite 136 is mounted to rotate freely around one of the shafts 1384 by means of a bearing 1385, for example, a roller bearing or plain bearing. There are a number of shafts 1384 and bearings 1385 equal to the number of satellites 136.

[0096] Figures 5 and 6 schematically represent a second embodiment of a mechanical reducer 200 according to the invention. [Fig. 5] is a schematic axial cross-sectional view of the mechanical reducer according to the invention, while [Fig. 6] is a schematic transverse cross-sectional view of the mechanical reducer in the CC plane of [Fig. 5]. This second embodiment differs from the first embodiment in that the mechanical reducer 200 further includes a reversing pinion 140 and the wheel 120 is configured to mesh with the pinion 110 via the reversing pinion 140.

[0097] The reversing pinion 140 has a main axis, called the third main axis C3, substantially parallel to the first main axis Cl of the pinion 110 and to the second main axis C2 of the wheel 120. The first, second and third main axes Cl, C2, C3 respectively of the pinion 110, the wheel 120 and the reversing pinion 140 are distinct from each other and parallel to each other.

[0098] The reversing pinion 140 pinion 110 is configured to be driven by the pinion 110 and to drive the wheel 120.

[0099] For this purpose, the reversing pinion 140 has external splines 144 intended to cooperate by meshing with the second external splines 114 of the pinion 110 and with the external splines 124 of the wheel 120.

[0100] Preferably, the external splines 144 of the reversing pinion 140 engaging the wheel 120 and the pinion 110 have the same teeth as the external splines 124 of the wheel 120 and those of the second external splines 114 of the pinion 110, i.e. straight or herringbone teeth.

[0101] According to this second embodiment, the first reduction stage of the mechanical reducer consists of the pinion 110, the reversing pinion 140 and the wheel 120.

[0102] In operation, the input shaft, for example a low-pressure turbine shaft of a turbomachine, drives the pinion 110 in rotation.

[0103] The pinion 110 drives the wheel 120 in rotation by meshing, either directly, according to the first embodiment, or via the reversing pinion 140, according to the second embodiment. The wheel 120 rotates more slowly than the pinion 110. This assembly, formed by the pinion 110, the wheel 120, and, where applicable, the reversing pinion 140, constitutes the first reduction stage of the mechanical reducer according to the invention.

[0104] The wheel 110 then drives by meshing the gear train 130 and more specifically the solar 132.

[0105] The satellites 136 are configured to be driven in rotation by meshing with the solar element 132 and the fixed ring 134. The rotation of the entire set of satellites 136 drives the satellite carrier 138 in rotation around the central axis of the solar element 132, which coincides with the second main axis C2 of the wheel 120.

[0106] The satellite carrier 138 being coupled to an output shaft, for example a drive shaft of a propeller or a blower, the rotation of the satellite carrier 138 causes the rotation of the propeller or the blower.

[0107] The invention, as described, thus proposes a two-stage mechanical reduction gear, the second stage of which, formed by a gear train, is housed and nested within the wheel of the first stage. The invention thus optimizes the size, particularly the axial dimensions, of the gearbox and therefore makes the mechanical gearbox more compact than those of the prior art, both axially and radially.

[0108] Furthermore, the invention allows accessories to be integrated onto the reducer without increasing the radial footprint of the motor.

[0109] The invention applies to any type of aircraft engine incorporating a fan or propeller and an offset between the axis of the fan shaft and the longitudinal axis of the engine.

Claims

Demands

1. Mechanical reducer (100; 200) for a turbomachine comprising: - a pinion (110) having a first main axis (Cl) and intended to be driven by an input shaft, - a wheel (120) having a second main axis (C2) parallel to the first main axis (Cl), the wheel (120) being configured to mesh with the pinion (110), and - a gear train (130) configured to be driven by the wheel (120) and comprising a sun gear (132) having a central axis coaxial with the second main axis (C2), a ring gear (134) arranged radially around the sun gear, planet gears (136) configured to mesh with the ring gear (134) and with the sun gear (132), and a planet carrier (138) mounted movably to rotation relative to the ring gear (134) and the sun gear (132) and supporting the planet gears (136), in which the crown (134),The solar element (132) and the satellite carrier (138) are substantially coaxial, and the satellite carrier (138) includes a coupling portion intended to be rotationally coupled with an output shaft. The mechanical reducer is characterized in that the solar element (132) is configured to be driven in rotation about the central axis by the wheel (120), and the wheel (120) includes a rim (1222) housing the ring gear (134) of the gear train (130).

2. Mechanical reducer (100) according to claim 1, wherein the wheel (120) is configured to mesh directly with the pinion (110).

3. Mechanical reducer (200) according to claim 1, comprising a reversing pinion (140) having a third main axis (C3) substantially parallel to the first main axis (Cl), the reversing pinion (140) being configured to mesh with the pinion (110) and with the wheel (120).

4. Mechanical reducer (100; 200) according to any one of the preceding claims, wherein the gear train (130) is an epicyclic gear train.

5. A mechanical reducer (100; 200) according to any one of the preceding claims, wherein the wheel (120) has a flange (1221) from which the wheel rim (1222) extends in a first direction and a first shaft (121) extending to start from the flask in a second direction opposite to the first direction.

6. Mechanical reducer (100; 200) according to claim 5, wherein the planet carrier (138) comprises a second shaft (1381) extending axially along the second main axis (C2) between an upstream end (1381a) and a downstream end (1381b), the second shaft (1381) being substantially coaxial with the first shaft (121), a downstream portion of the second shaft (1381) extends inside the first shaft (121) of the wheel (120) so that the downstream end (1381b) of the second shaft (1381) emerges from the first shaft (121) of the wheel (120).

7. Mechanical reducer (100; 200) according to claim 6, comprising at least two bearings (P5, P7) configured to support and guide the planet carrier (138), the two bearings (P5, P7) each being arranged on the second shaft (1381) of the planet carrier (138) respectively at the upstream end (1381a) and at the downstream end (1381b).

8. Mechanical reducer (100; 200) according to any one of the preceding claims, wherein the wheel (120) comprises a toothed wheel (125) configured to be mechanically connected to at least one piece of equipment of the turbomachine.

9. Aircraft turbomachine (10), comprising at least one mechanical reducer (100; 200) according to any one of the preceding claims.

10. Aircraft comprising at least one turbomachine (10) according to claim 9 or a mechanical reducer (100; 200) according to any one of claims 1 to 8.

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