Turbine engine for an aircraft

Abstract

The invention relates to a turbine engine (10) for an aircraft, this turbine engine (10) comprising a gas generator which has at least one compressor (1a, 1b), a combustion chamber (1c) and at least one turbine (1d, 1e), the at least one turbine (1d, 1e) having a shaft (3) connected to a propeller (S) via a mechanical reduction gear (6), the shaft (3) being coupled to the sun gear (11) via a gearbox (20) rotating in the opposite direction and at the same speed of rotation such that a rotation of the shaft (3) about its axis (X) at a given speed causes the sun gear (11) to rotate in the opposite direction about the same axis (X) at the same speed.

Description

[0001] DESCRIPTION

[0002] TITLE: TURBOMACHINE FOR AN AIRCRAFT

[0003] The present invention relates to the field of aircraft turbomachinery, in particular equipped with mechanical reducers.

[0004] Technical background

[0005] The technical background includes, in particular, documents US-B2-11,655,767 and US-A1-2023 / 130860.

[0006] The role of a mechanical reducer is to modify the speed ratio and torque between the input shaft and the output shaft of a mechanism.

[0007] Newer generations of turbofan engines, particularly those with a high bypass ratio, incorporate a mechanical gearbox to drive the shaft of a propulsion propeller, such as a fan. Typically, the gearbox's purpose is to transform the high rotational speed of the turbine shaft into a slower rotational speed for the propeller shaft.

[0008] Such a gearbox comprises a central pinion, called the sun gear, a ring gear, and pinions called planet gears, which mesh between the sun gear and the ring gear. The planet gears are held by a frame called the planet carrier. The sun gear, ring gear, and planet carrier are planetary gears because their axes of revolution coincide with the longitudinal axis of the turbomachine. The planet gears each have a different axis of revolution and are equally spaced around the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis of the turbomachine. Several gearbox architectures exist. In state-of-the-art turbomachinery, gearboxes are of the planetary or epicyclic type. In other similar applications, differential or compound architectures exist.- on a planetary reducer, the planet carrier is fixed and the ring forms the output shaft of the device which rotates in the opposite direction to the sun.

[0009] - on an epicyclic reducer, the ring is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar.

[0010] - On a differential gearbox, no element is fixed in rotation. The ring rotates in the opposite direction to the solar and satellite carrier.

[0011] Gearboxes can consist of one or more meshing stages. This meshing is achieved in various ways, such as by contact, friction, or magnetic field. There are several types of contact meshing, such as with spur or herringbone teeth.

[0012] To improve the performance of an aircraft equipped with turbomachinery, it may be preferable to rotate the propeller blades in different directions from one turbomachine to another. In such solutions, and to optimize costs and industrial processes, it is necessary to minimize the number of different parts used between turbomachines.

[0013] The gearbox is a device ideally positioned in the engine to reverse the direction of rotation of the propeller without impacting the compressor and the turbine.

[0014] The invention addresses this need, with the objective of minimizing the impact on the performance of the reducer in question compared to an optimized configuration without reversal of direction.

[0015] Summary of the invention

[0016] The invention proposes a turbomachine for an aircraft, this turbomachine comprising a gas generator having at least one compressor, a combustion chamber and at least one turbine, said at least one turbine having a shaft connected by a mechanical reducer to a propulsion propeller, the reducer having a solar element coupled to the shaft, a ring extending around the solar element, and satellites which are meshed respectively with the solar element and the ring and which are carried by a satellite carrier, characterized in that the shaft is coupled to the solar element by a gearbox with reversing direction of rotation and at the same speed of rotation so that a rotation of the shaft around its axis at a given speed causes a rotation in the opposite direction of the solar element around the same axis at the same speed.

[0017] The solution proposes adding a reversing gearbox upstream of a reducer; that is, a gearbox whose sole purpose is to reverse the direction of rotation. This gearbox is integrated between the input shaft and the sun gear of the reducer.

[0018] The solution proposed below is notably compatible:

[0019] • of a simple or multi-stage reducer;

[0020] • of an epicyclic, planetary or differential reducer,

[0021] • of straight, herringbone, helical, etc. teeth.

[0022] The turbomachine according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0023] - The gearbox includes:

[0024] - a first shaft section centered on said axis and comprising a first annular toothing extending around the axis, this first section being rotationally fixed to said shaft,

[0025] - a second shaft section centered on said axis and comprising a second annular toothing extending around the axis, this second section being rotationally fixed to said solar element, and

[0026] - sprockets comprising at least one first sprocket meshed with the first teeth of the first section, and at least one second sprocket meshed with the second teeth of the second section as well as with said at least one first sprocket; - said first section of shaft is formed in one piece with said shaft, or is coupled to said shaft by splines;

[0027] - said second section of tree is formed in one piece with said solar, or is coupled to said solar by grooves;

[0028] - said sprockets comprise only a first sprocket meshed with the first teeth of the first section, and a second sprocket meshed with the second teeth of the second section as well as with said first sprocket;

[0029] - said first pinion has a first set of teeth meshed with the first set of teeth of the first section, and a second set of teeth meshed with a third set of teeth of the second pinion which has a fourth set of teeth meshed with the second set of teeth of the second section;

[0030] - the first and fourth teeth of the sprockets have the same first diameter, and the second and third teeth of the sprockets have the same second diameter which is different from the first diameter, and for example larger than the first diameter;

[0031] -- the first and second sprockets are identical;

[0032] -- the first and second pinions differ only in the type of their teeth, which is chosen from straight, helical or herringbone teeth;

[0033] - the second and third teeth are meshed exactly at the level of said axis, or at a distance from this axis;

[0034] - said sprockets comprise several first sprockets meshed with the first toothing of the first section, and several second sprockets meshed with the second toothing of the second section, each of the second sprockets being further meshed with one or two of said first sprockets; -- said sprockets comprise two teeth of different diameters or of the same diameter, or a single toothing;

[0035] - the housing includes or carries bearings, in particular plain or with rollers, for guiding said first and second sections, and / or bearings, in particular plain or with rollers, for guiding the pinions; - the housing includes a casing which is fixed to a stator of the turbomachine;

[0036] - the casing includes an arrangement of branches comprising:

[0037] - at least two first branches oriented parallel to said axis and forming or supporting bearings for guiding the gears,

[0038] - at least two second branches oriented radially with respect to said axis and diametrically opposite with respect to the axis, each comprising a radially external extremity connected to one of the longitudinal extremities of each of the first two branches, and

[0039] - at least two third branches oriented radially with respect to said axis and diametrically opposite with respect to the axis, and each comprising a radially external end connected to the other of the longitudinal ends of each of the first two branches;

[0040] -- each of the second branches includes a radially internal end forming or carrying the guide bearing of the first section;

[0041] -- each of the third branches includes a radially internal end forming or carrying the guide bearing of the second section;

[0042] - the housing further comprises two lateral annular fixing arms extending around the axis and each carrying an annular fixing flange to a corresponding flange of the stator, a first of these annular arms being located at the junction between the radially external ends of the second arms and the aforementioned longitudinal ends of the first arms, and a second of these annular arms being located at the junction between the radially external ends of the third arms and the other aforementioned longitudinal ends of the first arms.

[0043] The present invention also relates to an aircraft comprising at least two turbomachines, each turbomachine comprising a gas generator having at least one compressor, a combustion chamber and at least one turbine, said at least one turbine having a shaft connected by a mechanical reducer to a propulsion propeller, the reducer having a solar element coupled to the shaft, a ring extending around the solar element, and satellites which are meshed respectively with the solar element and the ring and which are carried by a satellite carrier, characterized in that one of the turbomachines is as defined above, and the other of the turbomachines has its shaft which is coupled to the solar element by a gearbox with reversing direction of rotation and at the same speed of rotation, which is inactive, so that a rotation of the shaft around its axis at a given speed causes a rotation in the same direction of the solar element around the same axis at the same speed.

[0044] Advantageously, the inactive box includes:

[0045] - a first shaft section centered on said axis and comprising a first annular toothing extending around the axis, this first section being rotationally fixed to said shaft,

[0046] - a second shaft section centered on said axis and comprising a second annular toothing extending around the axis, this second section being rotationally fixed to said solar,

[0047] - gears comprising at least one first gear meshing with the first toothing of the first section, and at least one second gear meshing with the second toothing of the second section as well as with said at least one first gear. the first and second sections being rotationally fixed to a housing of the casing which carries said gears and which is free to rotate with respect to a stator of the turbomachine.

[0048] Brief description of the figures

[0049] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0050] [Fig.1] Figure 1 is a schematic view of an aircraft equipped with turbomachinery,

[0051] [Fig.2] Figure 2 is a schematic axial cross-sectional view of a turbomachine; [Fig.3] Figure 3 is a schematic axial cross-sectional view of a turbomachine according to the invention;

[0052] [Fig.4] Figure 4 is a schematic cross-sectional view of a reducer and a gear housing for a turbomachine according to the invention;

[0053] [Fig.5] Figure 5 is a schematic perspective and partial section view of the reducer and housing of the figure;

[0054] [Fig.6] Figure 6 is a schematic axial cross-sectional view of a turbomachine according to the invention;

[0055] [Fig.7] Figure 7 is a schematic cross-sectional view of a reducer and a gear housing for a turbomachine according to the invention;

[0056] [Fig.8] Figure 8 is a schematic perspective and partial section view of the reducer and housing of the figure;

[0057] [Fig.9] Figure 9 is a schematic perspective view of a gear housing according to one embodiment of the invention,

[0058] [Fig. 10] Figure 10 is a schematic perspective view of a gear housing according to one embodiment of the invention,

[0059] [Fig. 11] Figure 11 is a schematic perspective view of a gear housing according to an alternative embodiment of the invention,

[0060] [Fig.12] Figure 12 is a schematic perspective view of a gear case according to an alternative embodiment of the invention.

[0061] Detailed description of the invention

[0062] Figure 1 shows an aircraft with a central fuselage and two lateral wings, each carrying one or two turbomachines 10. As mentioned above, it can be more efficient to rotate the propulsion propellers of the turbomachines 10 in opposite directions. For example, the turbomachines 10 on one wing can rotate in one direction, and the turbomachines 10 on the other wing can rotate in a second direction opposite to the first. Alternatively, the two turbomachines 10 on each wing could rotate in opposite directions. Figure 2 shows a turbomachine 10 that conventionally comprises a fan propeller S, a low-pressure compressor 1a, a high-pressure compressor 1b, an annular combustion chamber 1c, a high-pressure turbine 1d, a low-pressure turbine 1e, and an exhaust nozzle 1h.The high-pressure compressor 1b and the high-pressure turbine 1d are connected by a high-pressure shaft 2 and together form a high-pressure (HP) unit. The low-pressure compressor 1a and the low-pressure turbine 1e are connected by a low-pressure shaft 3 and together form a low-pressure (LP) unit.

[0063] The blower propeller S is driven by a blower shaft 4 which is connected to the BP shaft 3 by means of a mechanical reducer 6. This reducer 6 is generally of the planetary or epicyclic type.

[0064] Although the following description relates to a planetary or epicycloidal type reducer, it also applies to a mechanical differential in which its three essential components, namely the planet carrier, the ring and the sun gear, are mobile in rotation, the rotational speed of one of these components depending in particular on the difference in speeds of the other two components.

[0065] The gearbox 6 is positioned in the upstream part of the turbomachine. A fixed structure schematically comprising, here, an upstream part 5a and a downstream part 5b which make up the motor or stator housing 5 is arranged to form an enclosure E surrounding the gearbox 6. This enclosure E is closed upstream by seals at the level of a bearing allowing the passage of the blower shaft 4, and downstream by seals at the level of the passage of the BP shaft 3.

[0066] Figure 3 shows a turbomachine 10 according to the invention. The preceding description, made with reference to Figure 2, applies to the turbomachine 10 of Figure 3.

[0067] In Figure 3, the reducer 6 is more clearly visible and schematically represented. The reducer is associated with a gearbox 20, which is located here directly at the input of the reducer 6. The reducer 6 can take on different configurations depending on whether certain parts are fixed or rotating. At the input, the reducer 6 is connected to the shaft BP 3 by the gearbox 20 and includes a solar element 11 coupled to the shaft BP 3 by the gearbox 20.

[0068] Typically, the solar 11, whose axis of rotation coincides with the X axis of the turbomachine 10, drives a series of gears called satellites 12, which are equidistant circumferentially on the same diameter around the axis of rotation X. This diameter is equal to twice the operating center distance between the solar 11 and the satellites 12. The number of satellites 12 is generally defined between three and seven for this type of application.

[0069] The set of satellites 12 is held by a frame called a satellite carrier 13. Each satellite 12 rotates around its own Y axis, and meshes with a ring gear 14.

[0070] At the output of the gearbox 6, we have: o in an epicyclic configuration, the set of planet gears 12 drives the planet carrier 13 in rotation around the X-axis of the turbomachine. The ring gear 14 is fixed to the motor or stator housing 5 via a ring carrier 15, and the planet carrier 13 is fixed to the fan shaft 4; o in a planetary configuration, the set of planet gears 12 is held by a planet carrier 13, which is fixed to the motor or stator housing 5. Each planet gear drives the ring gear, which is connected to the fan shaft 4 via a ring carrier 15.

[0071] Each satellite 12 is mounted to rotate freely using a bearing around a Y axis. The Y axes of rotation of the satellites 12 are distributed around the X axis and parallel to this X axis.

[0072] The distinctive feature of the turbomachine 10 in Figure 3 is that the BP 3 shaft is coupled to the solar element 11 by the reverse-rotating gearbox 20, which rotates at the same speed. Therefore, a rotation of the BP 3 shaft around the X-axis at a given speed results in a reverse rotation of the solar element 11 around the X-axis at the same speed. Figures 4 and 5 show a more concrete example of the implementation of the gearbox 6 and the gearbox 20.

[0073] In the example shown, the gear housing 20 includes:

[0074] - a first shaft section 22 centered on the X axis and comprising a first annular toothing 22a extending around the X axis, this first section 22 being rotationally fixed to the shaft BP 3,

[0075] - a second shaft section 24 centered on the X-axis and comprising a second annular toothing 24a extending around the X-axis, this second section 24 being rotationally fixed to the solar element 11, and

[0076] - sprockets 26, 28 comprising at least one first sprocket 26 meshed with the first toothing 22a of the first section 22, and at least one second sprocket 28 meshed with the second toothing 24a of the second section 24 as well as with said at least one first sprocket 26.

[0077] The first shaft section 22 can be formed in one piece with the shaft BP 3, or be coupled to this shaft by splines 30 as in the example shown.

[0078] The second shaft section 24 can be formed in one piece with the solar 11, or be coupled to the solar 11 by grooves 32 as in the example shown.

[0079] In the example shown, the gears 26, 28 consist only of gears 26, 28, therefore two in number. The first gear 26 is meshed with the first tooth 22a of the first section 22, and the second gear 28 is meshed with the second tooth 24a of the second section 24 as well as with the first gear 26.

[0080] We can see in the figures that the first pinion 26 can have a first tooth 26a meshed with the first tooth 22a of the first section 22, and a second tooth 26b meshed with a third tooth 28a of the second pinion 28 which has a fourth tooth 28b meshed with the second tooth 24a of the second section 24.

[0081] The first and fourth teeth 26a, 28b of the gears 26, 28 preferably have the same first diameter D1. The second and third teeth 26b, 28a of the gears 26, 28 preferably have the same second diameter D2 which is different from the first diameter D1, and for example larger than the first diameter D1.

[0082] The first and second pinions 26, 28 can be identical, as in the example shown.

[0083] Alternatively, the first and second pinions 26, 28 may differ only in the type of their teeth, which is chosen from straight, helical or herringbone teeth.

[0084] The second and third teeth 26b, 28a can be meshed exactly at the X axis, as is the case in this embodiment.

[0085] Since the gearbox has three external gears, the direction of rotation is reversed between its input and output. However, it is understood that the output speed is equal to the input speed. This allows the same parameters to be maintained at the input of the main gearbox, thus avoiding the need for redesign. It should be noted that if the gearbox is equipped with helical or herringbone gears, since the direction of rotation is reversed at the input of the main gearbox, it may be advisable to "reverse" the gears to maintain the direction of the axial forces acting on the teeth.

[0086] The housing 20 may include or carry bearings 34, 36, in particular plain, for guiding the first and second sections 22, 24, and / or bearings 38, 40 for guiding the pinions 26, 28.

[0087] The housing 20 preferably includes a casing 42 which is fixed to the stator 5 of the turbomachine 10, as schematically illustrated in figure 3.

[0088] In the example shown, the housing 42 comprises a branch arrangement including at least:

[0089] - at least two first straight branches 44 parallel to the X axis and forming or supporting the bearings 38, 40 for guiding the gears,

[0090] - at least two second branches 46 straight, oriented radially with respect to the X-axis and diametrically opposite with respect to the X-axis, and each comprising a radially external end 46b connected to one of the longitudinal ends of each of the first two branches 38, 40, and

[0091] - at least two third branches 48 straight, oriented radially with respect to the X axis and diametrically opposite with respect to the X axis, and each having a radially external end 48b connected to the other of the longitudinal ends of each of the first two branches 38, 40.

[0092] In the case where the first section 22 is guided by the bearing 34, each of the second branches 46 can include a radially internal end 46a forming or carrying the bearing 34 for guiding the first section 22.

[0093] In the case where the second section 24 is guided by the bearing 36, each of the third branches 47 can include a radially internal end 47a forming or carrying the bearing 36 for guiding the second section 24.

[0094] The housing 42 may further include two lateral annular mounting arms 50, 52 extending around the X axis and each carrying an annular flange 50a, 52a for mounting to a corresponding flange of the stator 5. A first of these annular arms 50 is located at the junction between the radially external ends 46b of the second arms 46 and the aforementioned longitudinal ends of the first arms 38, 40. A second of these annular arms 52 is located at the junction between the radially external ends 48b of the third arms 48 and the other aforementioned longitudinal ends of the first arms 38, 40.

[0095] In the context of aircraft 1 according to the invention mentioned above in relation to figure 1, this aircraft comprises at least two turbomachines 10.

[0096] Each turbomachine 10 is of the type illustrated in figure 2.

[0097] Among these turbomachines 10, one is as defined above with reference to figures 3 to 5. The other turbomachine 10' is preferably of the type illustrated in figures 6 to 8. This turbomachine 10' has its shaft BP 3 which is coupled to the solar 11 of the reducer 6 by a gearbox 20' with reversing direction of rotation and at the same speed of rotation, which is inactive or passivated, so that a rotation of the shaft BP 3 around its axis X at a given speed causes a rotation in the same direction of the solar 11 around the same axis X at the same speed.

[0098] The goal here is for the turbomachines 10, 10' to have their S propellers operating in opposite directions of rotation while having similar masses.

[0099] The inactive 20' housing of the 10' turbomachine may include:

[0100] - a first shaft section 22 centered on the X axis and comprising a first annular toothing 22a extending around the X axis, this first section 22 being rotationally fixed to the shaft BP 3,

[0101] - a second shaft section 24 centered on the X-axis and comprising a second annular toothing 24a extending around the X-axis, this second section 24 being rotationally fixed to the solar element 11, and

[0102] - sprockets 26, 28 comprising at least one first sprocket 26 meshed with the first toothing 22a of the first section 22, and at least one second sprocket 28 meshed with the second toothing 24a of the second section 24 as well as with said at least one first sprocket 26.

[0103] The first and second sections 22, 24 are rotationally fixed to the casing 42 of the housing 20', this casing 42 carrying the pinions 26, 28 and being free in rotation vis-à-vis the stator 5 of the turbomachine 10'.

[0104] For this purpose, in the example shown, the first and second sections 22, 24 include grooves 54, 56 engaged in complementary grooves of the casing 42, for example in place of the bearings 34, 36 mentioned above.

[0105] Thus, the housing 42 will be driven in rotation by the shaft 3, and consequently the gears 26 and 28 will follow the overall rotation. There is no meshing. It is worth noting that the housing 42 can retain the aforementioned flanges 50a and 52a. Depending on the type of turbomachine 10 or 10', it will then be decided whether these flanges 50a and 52a are attached to the stator 5 or not. This allows for a single reference for the housing 42. Thus, in the illustrations, we see that, for the turbomachine 10', the housing 42 has free flanges 50a and 52a and splines 54 and 56. For a reverse-rotating turbomachine 10, the flanges 50a and 52a are attached to the stator 5 and the splines are left free.

[0106] Figures 9 to 12 illustrate variant embodiments of the gear housing 20, 20' which can be used in the context of the turbomachine 10 or the turbomachine 10'.

[0107] In the case of Figure 9, there are two gears 26 and 28, as in the embodiments of Figures 4 and 5, the description of which applies here. The difference lies in the fact that the second and third gear teeth 26b and 28a mesh together at a distance from the X-axis.

[0108] In figures 10 to 12, several first gears 26 are meshed with the first toothing 22a of the first section 22, and several second gears 28 are meshed with the second toothing 24a of the second section 24. This solution allows the rotational torque to be distributed over several gears.

[0109] In Figure 10, each of the second gears 28 is meshed with one of the first gears 26. The first and second gears 26, 28 comprise two teeth of different diameters.

[0110] In Figure 11, each of the second gears 28 is meshed with two adjacent first gears 26, and each first gear 26 is meshed with two adjacent second gears 28. The first and second gears 26, 28 comprise two sets of teeth with different diameters.

[0111] In figure 12, the sprockets 26, 28 have two teeth of the same diameter, or a single tooth.

Claims

DEMANDS 1. Turbomachine (10) for an aircraft, said turbomachine (10) comprising a gas generator having at least one compressor (1a, 1b), a combustion chamber (1c) and at least one turbine (1d, 1e), said at least one turbine (1d, 1e) having a shaft (3) connected by a mechanical reduction gear (6) to a propulsion propeller (S), the reduction gear (6) having a sun gear (11) coupled to the shaft (3), a ring gear (14) extending around the sun gear (11), and planet gears (12) which are meshed respectively with the sun gear (11) and the ring gear (14) and which are carried by a planet carrier (13), the shaft (3) being coupled to the sun gear (11) by a reversible gearbox (20) with the same rotational speed such that a rotation of the shaft (3) about its axis (X) at a given speed causes a rotation in the opposite direction to the sun (11) around the same axis (X) at the same speed, characterized in that the gear case (20) comprises: - a first shaft section (22) centered on said axis (X) and comprising a first annular toothing (22a) extending around the axis (X), this first section (22) being rotationally fixed to said shaft (3), - a second shaft section (24) centered on said axis (X) and comprising a second annular toothing (24a) extending around the axis (X), this second section (24) being rotationally fixed to said solar (11), and - sprockets (26, 28) comprising at least one first sprocket (26) meshed with the first toothing (22a) of the first section (22), and at least one second sprocket (24) meshed with the second toothing (24a) of the second section (24) as well as with said at least one first sprocket (26).

2. Turbomachine (10) according to claim 1, wherein said first shaft section (22) is formed in one piece with said shaft (3), or is coupled to said shaft (3) by splines (30).

3. Turbomachine (10) according to claim 1 or 2, wherein said second shaft section (24) is formed in one piece with said solar (11), or is coupled to said solar (11) by splines (32).

4. Turbomachine (10) according to any one of claims 1 to 3, wherein said pinions (26, 28) comprise only a first pinion (26) meshed with the first toothing (22a) of the first section (22), and a second pinion (24) meshed with the second toothing (24a) of the second section (24) as well as with said first pinion (26).

5. Turbomachine (10) according to claim 4, wherein said first pinion (26) has a first tooth (26a) meshed with the first tooth (22a) of the first section (22), and a second tooth (26b) meshed with a third tooth (28a) of the second pinion (28) which has a fourth tooth (28b) meshed with the second tooth (24a) of the second section (24).

6. Turbomachine (10) according to claim 5, wherein the first and fourth teeth (26a, 28b) of the gears (26, 28) have the same first diameter (D1), and the second and third teeth (26b, 28a) of the gears (26, 28) have the same second diameter (D2) which is different from the first diameter (D1), and for example larger than the first diameter (D1).

7. Turbomachine (10) according to claim 5 or 6, wherein the second and third gears (26b, 28a) are meshed exactly at said axis (X), or at a distance from said axis (X).

8. Turbomachine (10) according to any one of claims 1 to 3, wherein said pinions (26, 28) comprise several first pinions (26) meshed with the first toothing (22a) of the first section (22), and several second pinions (28) meshed with the second toothing (24a) of the second section (24), each of the second pinions (24) being further meshed with one or two of said first pinions (26).

9. Turbomachine (10) according to any one of claims 1 to 8, wherein the housing (20) comprises or carries bearings (34, 36), in particular plain bearings, guiding the said first and second sections (22, 24), and / or the bearings (28, 40), in particular smooth, guiding the pinions (26, 28).

10. Turbomachine (10) according to any one of the preceding claims, wherein the casing (20) comprises a housing (42) which is fixed to a stator (5) of the turbomachine (10).

11. Turbomachine (10) according to claims 9 and 10, wherein the casing (42) comprises an arrangement of arms including: - at least two first branches (44) oriented parallel to said axis (X) and forming or carrying bearings (38, 40) for guiding the pinions (26, 28), - at least two second branches (46) oriented radially with respect to said axis (X) and diametrically opposite with respect to the axis (X), and each comprising a radially external end (46b) connected to one of the longitudinal ends of each of the first two branches (44), and - at least two third branches (48) oriented radially with respect to said axis (X) and diametrically opposite with respect to the axis (X), and each comprising a radially external end (48b) connected to the other of the longitudinal ends of each of the first two branches (44).

12. Turbomachine (10) according to claim 11, wherein the housing (42) further comprises two lateral annular mounting arms (50, 52) extending around the axis (X) and each carrying an annular flange (50a, 52a) for mounting to a corresponding flange of the stator (5), a first of these annular arms (50) being located at the junction between the radially external ends (56b) of the second arms (46) and the aforementioned longitudinal ends of the first arms (44), and a second of these annular arms (52) being located at the junction between the radially external ends (48b) of the third arms (48) and the aforementioned other longitudinal ends of the first arms (44).

13. Aircraft comprising at least two turbomachines (10, 10'), one of the turbomachines (10) being as defined in one of the claims previous, and the other turbomachine (10') comprising a gas generator having at least one compressor (1a, 1b), a combustion chamber (1c) and at least one turbine (1d, 1e), said at least one turbine (1d, 1e) having a shaft (3) connected by a mechanical reduction gear (6) to a propulsion propeller (S), the reduction gear (6) having a solar element (11) coupled to the shaft (3), a ring gear (14) extending around the solar element (11), and satellites (12) which are meshed respectively with the solar element (11) and the ring gear (14) and which are carried by a satellite carrier (13), the shaft (3) of the other turbomachine (10') being coupled to the solar element (11) by a reversible, same-speed gearbox (20') which is inactive, so that a rotation of the tree (3) around its axis (X) at a given speed causes a rotation in the same direction of the sun (11) around the same axis (X) at the same speed.

14. Aircraft according to the preceding claim, in which the inactive casing (20') comprises: - a first shaft section (22) centered on said axis (X) and comprising a first annular toothing (22a) extending around the axis (X), this first section (22) being rotationally fixed to said shaft (X), - a second shaft section (24) centered on said axis (X) and comprising a second annular toothing (24a) extending around the axis (X), this second section (24) being rotationally fixed to said solar (11), - pinions (26, 28) comprising at least one first pinion (26) meshed with the first toothing (22a) of the first section (22), and at least one second pinion (28) meshed with the second toothing (24a) of the second section (24) as well as with said at least one first pinion (22). the first and second sections (22, 24) being rotationally fixed to a housing (42) of the casing (20') which carries said pinions (26, 28) and which is free to rotate with respect to a stator (5) of the turbomachine (10').

Images