REDUCER WITH A SOLAR GUIDING BEARING

Abstract

The invention relates to a coupling system (50) comprising an input shaft (54) extending along a longitudinal axis (X), an output shaft (56) and a reducer (52) coupling the input shaft (54) to the output shaft (56), the reducer being an epicyclic gear reducer comprising a sun driven in rotation by the input shaft (54), a ring surrounding the sun (58) and a plurality of satellites (57), carried by a satellite carrier, meshing with the sun (58) and the ring, the output shaft (56) being driven in rotation by one of the ring and the satellite carrier (57), in which the coupling system (50) further comprises a bearing (60) surrounded at least in part by the sun (58) and guiding the sun (58) in rotation about the longitudinal axis (X) relative to a fixed structure. Figure for the abridged version: Fig. 4

Description

Title of the invention: REDUCER COMPRISING A SOLAR GUIDING BEARING Scope of the invention

[0001] The present invention relates to mechanical gearboxes and the management of misalignments between a gearbox and the input shaft coupled to it. More particularly, the present invention relates to aircraft propulsion systems and the management of misalignments between the turbine shaft and the fan gearbox of such a system. Technological background

[0002] 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 relatively high rotational speed of the shaft of a gas turbine rotor into a slower rotational speed for the shaft driving the fan.

[0003] Most often, the reducers used in such turbomachines are epicyclic gear reducers comprising a central pinion, called the sun gear, a ring gear coaxial with the sun gear, surrounding the latter, and pinions, called satellites, which are meshed between the sun gear and the ring gear and are held by a frame called the satellite carrier. Classically, the sun gear is driven in rotation by the turbine shaft and the blower shaft is driven in rotation by the satellite carrier (when the reducer is in epicyclic configuration) or by the ring gear (when the reducer is in planetary configuration).

[0004] For optimal operation of such a turbomachine, the various components connected by a shaft must be perfectly aligned with each other and with the shaft itself. Excessive misalignment of a shaft relative to the components to which it is connected, particularly the gearbox, can cause damage to the shaft itself, potentially leading to its breakage, or to the components connected to the shaft, which can wear out rapidly, especially due to friction. However, since a certain degree of misalignment, which may be horizontal and / or vertical, and axial displacement of a shaft are unavoidable, it is known to position one or more flexible coupling devices on the shaft.Thus, it is known to position flexible coupling devices on the turbine shaft, between the upstream bearing and the gearbox, to prevent misalignment between the upstream bearing and the gearbox from causing damage or wear to the shaft, the low-pressure turbine and / or the gearbox, particularly in solar applications.

[0005] These flexible coupling devices must meet opposing constraints. On the one hand, they must be sufficiently flexible so as not to induce excessive overload on the teeth of the solar element. On the other hand, they must be sufficiently rigid so as not to resonate within the operating range of the turbomachine.

[0006] However, in order to reduce the energy consumption of such turbomachinery, the aim is to minimize the size of the gearboxes while maximizing their reduction ratio, which leads to a reduction in the load level that the solar array can handle. Under these conditions, it becomes increasingly difficult to design flexible coupling devices so that they can meet the aforementioned dual constraint.

[0007] In particular, flexible coupling devices minimize axial misalignments but do not allow to limit radial misalignments at the level of the reducer. Description of the invention

[0008] An objective of the invention is to enable the coupling of a gas turbine shaft to a reducer in such a way as to reduce the loads transmitted to the input pinion while exhibiting a resonance frequency that is outside the operating range of the gas turbine.

[0009] To this end, the invention relates to a coupling system comprising an input shaft extending along a longitudinal axis, an output shaft and a reducer coupling the input shaft to the output shaft, the reducer being an epicyclic gear reducer comprising a sun driven in rotation by the input shaft, a ring surrounding the sun and a plurality of satellites, carried by a satellite carrier, meshed with the sun and the ring, the output shaft being driven in rotation by one of the ring and the satellite carrier, in which the coupling system further comprises a bearing surrounded at least in part by the sun and guiding the sun in rotation around the longitudinal axis relative to a fixed structure.

[0010] The coupling system described above limits the impact of radial movements of the input shaft on the gearbox. Indeed, during operation of the coupling system, the pinion is held radially by the bearing, and the radial stresses to which it is subjected, particularly due to misalignments of the input shaft, are dampened. This radial support significantly increases the natural bending frequency of the shaft. The loads borne by the input pinion are thus limited, preventing excessive wear.

[0011] When it is said that the bearing is partially surrounded by the solar element, this means that the bearing is surrounded by the solar element over at least part of its length. Preferably, the bearing is surrounded by the solar element over its entire length.

[0012] Preferably, one of the ring and planet carrier parts is fixed, and the output shaft is driven in rotation by the other of the ring and planet carrier parts. The fixed structure is then that of the ring and planet carrier parts, which are fixed.

[0013] According to particular embodiments of the invention which may be taken alone or in combination: - the bearing is a plain bearing and the coupling system further includes a lubricant supply device connected to a fixed element and allowing lubricant to be injected at an interface between the plain bearing and the solar element; preferably, the fixed element is an element of the gearbox, for example the planet carrier or the ring gear; the interface is an area located between an outer surface of the plain bearing and an inner surface of the solar element and in which these two surfaces are at a constant distance from each other, this distance being at most a few millimeters; thus, at the interface, the inner surface of the solar element and the outer surface of the plain bearing have complementary shapes; - the plain bearing has at least one set of orifices connected to the lubricant supply device and opening at the interface between the bearing and the solar element, said at least one set having at least two orifices; thus, when the input shaft drives the solar element in rotation, the interface is supplied with lubricant at different points on its circumference by means of the orifices and is then distributed under the effect of the rotation of the solar element; the lubricant is thus distributed homogeneously at the interface; - the orifices of an assembly are distributed over the circumference of the bearing and in the same radial plane extending in a plane perpendicular to the longitudinal axis; - the coupling system further comprises at least one fastening device, said fastening device being connected to the satellite carrier; the fastening device may in particular be connected to the pivot of the satellite carrier, for example by an elongated portion passing through the pivot along an axis parallel to the longitudinal axis; preferably, the satellite carrier may be fixed; - the lubricant supply device is integrated into the fastening device; in this way, the space required around the bearing and the reducer is limited; - the fixing device includes an elongated portion passing through a satellite carrier pivot along an axis parallel to the longitudinal axis (X) and the lubricant supply device includes a supply conduit extending inside the elongated portion; - the supply device comprises a main supply conduit extending inside the plain bearing along the longitudinal axis, said main supply conduit being connected to each of the ports opening at the interface by a secondary supply conduit; thus, the various secondary supply conduits are supplied by a single source of lubricant; - the bearing is a cylinder of constant diameter; the interface then extends over part of the inner surface of the solar, and preferably over the entire inner surface of the solar; the bearing is preferably a smooth bearing comprising at least one set of orifices; - the bearing comprises an upstream portion and a downstream portion, the upstream portion and the downstream portion each having an interface with the solar element and being connected to each other by a central portion having a radial dimension less than a radial dimension of the upstream and downstream portions; the bearing is preferably a smooth bearing and the upstream and downstream portions each then comprise at least one set of orifices so as to be able to lubricate each of the portions; - the bearing comprises an upstream frustoconical portion and a downstream frustoconical portion connected to each other by their smaller diameter ends in a central part, the solar being configured to have an interface with both the upstream and downstream frustoconical portions; such a bearing has the advantage of being able to hold the solar in such a way as to limit its radial displacements but also its axial displacements; the bearing is preferably a smooth bearing and the central part is provided with at least one set of orifices;

[0014] - the input tree is formed of several segments, including a coupled proximal segment in the solar system, a distal section and an intermediate section interposed between the distal and proximal sections, the input shaft further comprising a flexible coupling device comprising a first and a second flexible coupling members connecting the intermediate section respectively to the distal and proximal sections, each flexible coupling member permitting longitudinal translations and rotations around axes perpendicular to the longitudinal axis, and in particular permitting only said translations and rotations; the flexible coupling members allow to absorb part of the misalignments and / or displacements of the input shaft and are thus complementary to the bearing;Since misalignments and / or displacements of the input shaft are compensated by the flexible coupling elements and the bearing, the flexibility of the coupling elements can be limited so as to prevent them from resonating within the operating range of the propulsion system in which the coupling system is placed; and; - Each flexible coupling member comprises a first ring connected to the intermediate section, a second ring connected to one of the distal and proximal sections, a crown surrounding the first and second rings, a first flexible annular structure interposed between the first ring and the crown, and a second flexible annular structure interposed between the second ring and the crown.

[0015] The invention also relates to an aircraft propulsion system comprising a gas generator, a fan, and a coupling system such as that described above, the input shaft being driven in rotation by a gas generator rotor and the output shaft being rotatable in conjunction with a fan rotor.

[0016] The invention also relates to an aircraft comprising a coupling system or a propulsion system as previously described. Brief description of the Figures

[0017] Other features and advantages of the invention will become apparent from the following description, given solely by way of example and with reference to the accompanying drawings, in which:

[0018] Fig. 1 is a schematic top view of an aircraft according to one embodiment of the invention;

[0019] The [Fig.2] is a schematic partial cross-sectional view of a propulsion system of the aircraft of the [Fig.1];

[0020] Fig. 3 is a schematic view of a reducer of the propulsion system of Fig. 2;

[0021] Fig. 4 is a partial schematic longitudinal section view of a coupling system according to the invention;

[0022] The [Fig.5a] is a partial schematic longitudinal sectional view of a coupling system according to a first embodiment of the invention;

[0023] Fig. 5b is a schematic longitudinal cross-sectional view of a coupling system according to a second embodiment of the invention;

[0024] Fig. 5c is a schematic longitudinal cross-sectional view of a coupling system according to a third embodiment of the invention; and Fig. 6 is a schematic longitudinal cross-sectional view of a coupling system according to an alternative embodiment of the invention. Detailed description of a project example

[0026] In the example shown, the aircraft 1 is an airplane. This conventionally comprises a fuselage 4, a tail assembly 6, and two wings 8. The propulsion systems 10 are two in number and are each housed under a respective wing 8. Alternatively (not shown), the propulsion systems 10 are arranged along the fuselage 4, for example, near the tail assembly 6. Alternatively (also not shown), the propulsion systems 10 are arranged along the fuselage 4, for example, near the tail assembly 6. represented), aircraft 1 comprises a single propulsion system 10 or at least three propulsion systems 10.

[0027] One of the propulsion systems 10 is shown in [Fig.2].

[0028] In [Fig.2], the propulsion system 1 has a main direction extending along a longitudinal axis X. The propulsion system 1 comprises a blower section 2 and a primary body 3, often called a "gas generator".

[0029] The blower section 2 comprises a blower 22 and a blower housing 12. The blower 22 comprises a blower rotor 9. The blower housing 12 surrounds the blower rotor 9. The blower rotor 9 is rotatably mounted relative to the blower housing 12.

[0030] The fan rotor 9 comprises a fan hub 13 and fan blades 14 extending radially from the hub 13. The fan blades 14 may be fixed relative to the fan hub 13 or have variable pitch. In the latter case, each of the fan blades 14 is pivotally mounted relative to the fan hub 13 about a pitch axis and is connected to a pitch-changing mechanism mounted in the propulsion system 1. The pitch-changing mechanism allows the pitch angle of the fan blades 14 to be adjusted according to the flight phases.

[0031] In this example, the blower section 2 also includes a blower stator 16 fixedly mounted on the blower housing 12. The blower stator 16 includes fixed vanes 17 generally referred to as "outlet vanes" (or "OGV", for "Outlet Guide Vane" in English).

[0032] Alternatively, the outlet blades 17 could have a variable pitch. If so, and similarly to the fan blades 14 of the fan rotor 9, the base of the outlet blades 17 is pivotally mounted about a pitch axis and is connected to a pitch-changing mechanism (not shown), the pitch being adjusted according to the flight phases by the pitch-changing mechanism.

[0033] The primary body 3 comprises a compressor section 18, a combustion chamber 6 and a turbine section 19.

[0034] The compressor section 18 includes a low pressure compressor 4 and a high pressure compressor 5.

[0035] The turbine section 19 comprises a high-pressure turbine 7 and a low-pressure turbine 8.

[0036] The propulsion system 1 includes a low-pressure shaft 54 ​​connecting the low-pressure turbine 4 to the low-pressure compressor 8, the low-pressure shaft 54 ​​being mounted rotatably relative to a housing 26 of the primary body 3 around the longitudinal axis X.

[0037] When the propulsion system 1 is in operation, the low-pressure turbine 8 drives the low-pressure compressor 4 in rotation via the low-pressure shaft 54.

[0038] The propulsion system 1 further comprises a high-pressure shaft 10 connecting the high-pressure turbine 7 to the high-pressure compressor 5, the high-pressure shaft 10 being mounted rotatably relative to the housing 26 around the longitudinal axis X. The high-pressure shaft 10 is coaxial with the low-pressure shaft 54 ​​and extends around the low-pressure shaft 54.

[0039] When the propulsion system 1 is in operation, the high-pressure turbine 7 drives the low-pressure compressor 4 in rotation via the low-pressure shaft 54.

[0040] When the propulsion system is in operation, an airflow F entering the propulsion system 1 passes through the blower 22 and is then divided between a primary airflow Fl and a secondary airflow F2, which flow upstream to downstream in the propulsion system 1.

[0041] The secondary airflow F2, also called the "bypass airflow", flows in a secondary channel around the primary body 3. The secondary airflow F2 cools the periphery of the primary body 3 and is used to generate most of the thrust provided by the propulsion system 1.

[0042] The primary airflow Fl flows in a primary channel 29 inside the primary body 3, passing successively through the compressor section 18 (low pressure compressor 4 and high pressure compressor 5), the combustion chamber 6 where it is mixed with fuel to serve as an oxidizer, and the turbine section 19 (high pressure turbine 7 and low pressure turbine 8).

[0043] Furthermore, the turbomachine 10 includes a coupling system 50 by which the low-pressure turbine 8 drives the fan 22 in rotation about a longitudinal axis X, the coupling system 50 comprising the low-pressure shaft 54. The coupling system 50 includes a reducer 52 allowing coupling an input shaft, which is the low-pressure shaft 54, with an output shaft 56 which is the shaft driving the fan 12.

[0044] With reference to [Fig.3], the reducer 52 has an input pinion 58 which is driven in rotation by the input shaft 54.

[0045] Preferably, the reducer 52 is, as shown, an epicyclic gear reducer comprising a sun gear forming the input pinion 58, a ring gear 53 surrounding the sun gear 58, and a plurality of planet gears 55, carried by a planet carrier and meshed with the sun gear 58 and the ring gear. One of the ring gear 53 and the planet carrier is fixed, and the output shaft 56 is driven in rotation by the other of the ring gear 53 and the planet carrier.

[0046] With reference to [Fig.4], a coupling system 50 according to the invention, shown partially in [Fig.4], further comprises a bearing 60 surrounded at least in part by the solar 58 and guiding the solar 58 in rotation around the longitudinal axis X relative to a fixed structure, in particular a housing (not shown) of the turbomachine 10. An outer surface 65 of the bearing 60 is thus surrounded by an inner surface 59 of the solar 58, thus forming an interface 61.

[0047] The coupling system described above limits the impact of radial displacements of the input shaft on the gearbox. Indeed, during operation of the coupling system, the solar element is held radially by the bearing, and the radial stresses to which it is subjected, particularly due to misalignments of the input shaft, are dampened. This radial support significantly increases the natural bending frequency of the shaft. The loads borne by the input pinion are thus limited, preventing excessive wear.

[0048] The bearing 60 can have different shapes according to a longitudinal section and has a symmetry of revolution around the longitudinal axis X.

[0049] Furthermore, the bearing 60 is connected to the reducer 52 by the bearing of the ring gear 53 or the planet carrier 57, which is fixed. Preferably, the planet carrier 57 is fixed and the output shaft 56 is driven in rotation by the ring gear 53.

[0050] The bearing 60 is in particular connected to the reducer 52 by a first fixing device 70 formed by a fixing plate 72 positioned at an upstream end of the bearing 60 and fixed to the reducer 52. Preferably, the fixing plate 72 extends substantially along a plane perpendicular to the axis of revolution X.

[0051] Preferably, the bearing 60 is a plain bearing, and the rotational mobility of the solar element 58 relative to the bearing 60 is facilitated by lubricant (preferably oil) injected at an interface 61 between the bearing 60 and the solar element 58. The injected oil is then in contact with the outer surface 65 of the bearing 60 and with the inner surface 59 of the solar element 58, allowing these two surfaces to move relative to each other. The coupling system 50 then includes an oil supply device 62 connected to the gearbox, which allows oil to be injected at the interface 61.

[0052] The oil supply device 62 includes a main oil supply conduit 63 which is connected, on the one hand, to an oil reservoir 64, and, on the other hand, to the bearing 60. In the bearing 60, the main supply conduit 63 opens at the interface 61 by means of ports 67 located on the outer surface 65 of the plain bearing 60.

[0053] The plain bearing 60 comprises one or more sets of holes 67, each set comprising at least two holes, preferably regularly spaced around the circumference of the bearing 60. The plain bearing 60 may include, for example, one, two, or three sets of holes. The holes 67 of each set are located in the same radial plane which extends perpendicularly to the longitudinal axis.

[0054] Thus, the interface 61 is supplied with oil at different points around its circumference and the oil can be distributed homogeneously at the interface 61. Indeed, the oil is injected by means of the orifices 67 and then distributed under the effect of the rotation of the solar 58 around the bearing 60.

[0055] According to one possible embodiment, the sets of orifices can be distributed differently, for example in alignment along a longitudinal axis or in a staggered pattern.

[0056] Each orifice 67 is connected to the main supply conduit 63 by a secondary oil supply conduit 66 which extends inside the bearing 60. Thus, the various secondary supply conduits 66 are supplied by a single source of oil.

[0057] In this embodiment, the main oil supply conduit 63 is integrated into a second fixing device which is formed by the structure through which the supply conduit passes.

[0058] According to one possible embodiment, the oil supply device may include one or more oil reservoirs for supplying one or more main supply lines.

[0059] Preferably, the planet carrier 57 is fixed and the ring 53 drives the output shaft 56 in rotation. The oil supply device 62 is then connected to the plain bearing 60 and the planet carrier 57.

[0060] The supply device 62 includes a second fixing device 68 within which the main supply conduit 63 extends. The second fixing device 68 includes at least a first elongated portion 69 inserted into the plain bearing 60 through its axis of revolution which is the longitudinal axis X.

[0061] Preferably, the second mounting device 68 also includes a second elongated portion 74 passing through the pivot of one of the satellites 55 and traversing it from upstream to downstream along an axis parallel to the longitudinal axis X. This second elongated portion 74 also allows passage of the main supply conduit 63. The oil reservoir 64 is preferably positioned downstream of the reducer 52 and is connected to the second elongated portion 74 and to the main supply conduit 63. The oil reservoir 64 can also be positioned upstream of the reducer 52.

[0062] The first elongated portion 69 and the second elongated portion 74 are connected by a third elongated portion 75 which can also be fixed to the satellite carrier 57 but not necessarily.

[0063] The main supply conduit 63 extends inside the first, second and third elongated portions, and is connected to the oil reservoir 64.

[0064] According to a first embodiment shown in [Fig. 5a], the plain bearing 60 is a cylinder of constant diameter surrounded by the solar element 58 along its entire length. The plain bearing comprises a single set of orifices 67, each positioned on the surface of the plain bearing 60 and each connected to a secondary supply conduit 66. The assembly comprises at least three orifices distributed regularly on the surface of the bearing 60. The orifices 67 are located in a radial plane P extending perpendicularly to the longitudinal axis X and positioned at the center of the bearing 60.

[0065] The oil is thus injected so as to form a homogeneous film throughout the interface 61 between the bearing 60 and the solar 58. Preferably, the oil is distributed from the orifices 67 towards the ends of the bearing 60 under the effect of the rotation of the solar 58.

[0066] In this embodiment, the oil supply device 62, the second fastening device 68 and the first fastening device 70 are as described with reference to [Fig.4].

[0067] In a second embodiment shown in [Fig. 5b], the coupling system differs from that of the first embodiment in that the plain bearing 60 comprises an upstream portion 76 and a downstream portion 78, each having an interface with the solar element. The upstream portion 76 and the downstream portion 78 are connected by a central portion 77, which has a radial dimension smaller than the radial dimension of both the upstream and downstream portions. The upstream portions 76 and 78 thus form two axially separated and smaller bearings, each comprising a set of orifices 67 such as that described for the first embodiment. The two upstream portions 76 and 78 allow for a total interface surface area smaller than that of the first embodiment, while still providing sufficient guidance of the solar element. In particular, the reduced interface allows for the use of less oil.

[0068] The first fastening device 70 is connected to the end of the upstream portion 76 opposite the central portion 77.

[0069] In this embodiment, the oil supply device 62 has two branches to the secondary supply lines 66, a first branch 79 at the upstream portion 77 and a second branch 79' at the downstream portion 78.

[0070] In a third embodiment shown in [Fig.5c], the coupling system 50 differs from those of the first and second embodiments by the shape of the plain bearing 60, by the second fixing device 68 and by the oil supply device 62.

[0071] In this third embodiment, the plain bearing 60 comprises an upstream frustoconical portion 80 and a downstream frustoconical portion 82 connected to each other at their smaller diameter ends in a central portion 83. The plain bearing 60 then comprises a set of orifices 67 positioned at the central portion so that the oil can be distributed towards each frustoconical portion under the effect of centrifugal force. The first fastening device 70 is then connected to the wider end of the upstream frustoconical portion 80.

[0072] Such a bearing has the advantage of being able to maintain the solar element 58 in such a way as to limit its radial displacements as well as its axial displacements. To this end, the bearing is configured to have an interface with both the upstream and downstream frustoconical portions and thus have a shape complementary to that of the smooth bearing.

[0073] In this embodiment, the second mounting device 68 is identical to that of the first and second embodiments but further comprises an additional elongated portion 84 extending between the first and second elongated portions 69 and 74 and along an axis parallel to these two portions. The additional elongated portion 84 is fixed to the satellite carrier 57 and forms part of the support means for the second mounting device 68 on the satellite carrier s.

[0074] Furthermore, in this embodiment, the oil reservoir 64 is positioned upstream of the reducer 52 and the main supply conduit 63 then connects to the second fixing device 68 at the level of the third portion 75.

[0075] According to one possible embodiment, the second fastening device 68 and the lubricant supply device 62 can be identical to those of the first and second embodiments, except for the elements located in the plain bearing 60 which are specific to each embodiment.

[0076] According to a fourth possible embodiment, not shown, the bearing could be concave in cross-section, with the largest diameter located in the middle of the bearing. The inner surface of the solar element 58 is then convex so as to conform to the bearing and form a ball joint. According to this embodiment, the bearing holds the solar element in place, limiting both its radial and axial displacements.

[0077] According to one possible embodiment, shown in [Fig. 6] and applicable to the embodiments described above, the input shaft 54 ​​comprises a proximal section 86 connected to the solar element 58 of the reducer 52, a distal section 88 connected to the low-pressure turbine 8 and an intermediate section 87 interposed between the distal section 88 and the proximal section 86. Furthermore, the input shaft 54 ​​comprises flexible coupling members 89a,b connecting the intermediate section 87, on the one hand, to the distal section 88 and, on the other hand, to the proximal section 86.

[0078] In particular, the flexible coupling members 89a,b comprise a first flexible coupling member 89a connecting the intermediate section 76 to the distal section 78 of the shaft 54 ​​and a second flexible coupling member 89b connecting the intermediate section 76 to the proximal section 86.

[0079] Each flexible coupling member 89a,b is configured to allow longitudinal translations and rotations about axes perpendicular to the longitudinal axis X. The flexible coupling members 89a,b thus allow misalignments and longitudinal displacements of the solar 58 relative to the input shaft 54, in particular relative to the distal section 88, which limits the loads experienced by the solar 58. The flexible coupling members 89a,b together form, in particular, between the proximal section 86 and the distal section 88 of the input shaft 54, a relatively homokinetic coupling link, also called a homokinetic joint.

[0080] The flexible coupling elements allow for the absorption of some of the misalignments and / or displacements of the input shaft, thus complementing the bearing. Since the misalignments and / or displacements of the input shaft 54 ​​are compensated by the flexible coupling elements 89a,b and by the bearing 60, the flexibility of the coupling elements can be limited to prevent them from resonating within the operating range of the propulsion system in which the coupling system is located.

[0081] The downstream flexible coupling member 89a comprises a first ring 90a connected to the intermediate section 76, a second ring 91a connected to the distal section 88, and a crown 92a surrounding the first and second rings 90a and 91a. Furthermore, the downstream flexible coupling member 89a includes a first flexible annular structure 93a interposed between the first ring 90a and the crown 92a, and a second flexible annular structure 94a interposed between the second ring 81a and the crown 92a.

[0082] The upstream flexible coupling member 89b is identical to the downstream flexible coupling member 89a except that the second ring 91b is connected to the proximal section 86. The references for the upstream flexible coupling member 89b are identical to those of the downstream flexible coupling member 89a but are indexed "b" instead of "a".

[0083] The flexible coupling members 89a,b allow relative movements between the intermediate section 87 and the distal section 88, on the one hand, and between the intermediate section 87 and the proximal section 86, on the other hand, while limiting the amplitude of these movements. The flexible annular structures allow for the absorption of some of the misalignments and / or displacements of the sections relative to each other through elastic deformations.

[0084] Preferably, the flexible annular structures 93a, 93b, 94a and 94b are each formed by a solid circular metallic membrane pierced in its center so as to allow good transmission of the torque around the longitudinal axis and also so as to have good resistance over time.

[0085] The downstream flexible coupling members 89a and upstream members 89b constitute what are commonly called "flexors". In this embodiment, they are formed by a double-diaphragm longitudinal shaft seal, each diaphragm having a disc shape extending radially with respect to the shaft. They can also be formed by another type of longitudinal shaft seal, such as a multi-diaphragm longitudinal shaft seal or a metal diaphragm coupling seal.

[0086] Furthermore, according to a possible variant not shown, the input shaft 54 ​​can be formed in one piece. The downstream and upstream flexible coupling members 89a, 89b are then one-piece members that can be formed from radially enlarged portions of the input shaft 54. They are typically machined from a solid block of the input shaft 54.

[0087] Advantageously, the bearing 60 of the input shaft 54 ​​to the solar element 58 allows the flexible coupling members 89a and 89b to be sized so that their resonant frequency lies outside the operating range of the propulsion system 10. Indeed, the flexible coupling members absorb some of the misalignments and / or displacements of the input shaft and are thus complementary to the bearing. The misalignments and / or displacements of the input shaft are thus compensated by the combination of the flexible coupling members and the bearing, and the flexibility of each coupling member can then be limited to prevent them from resonating within the operating range of the propulsion system in which the coupling system is located.

Claims

Demands

1. Aircraft propulsion system (10) comprising a gas generator, a fan (12) and a coupling system (50), the coupling system (50) comprising an input shaft (54) extending along a longitudinal axis (X), an output shaft (56) and a reduction gear (52) coupling the input shaft (54) to the output shaft (56), the reduction gear being an epicyclic gear reduction gear comprising a solar element driven in rotation by the input shaft (54), a ring surrounding the solar element (58) and a plurality of satellites (57), carried by a satellite carrier s, meshed with the solar element (58) and the ring, the output shaft (56) being driven in rotation by one of the ring and the satellite carrier s (57),in which the coupling system (50) further comprises a bearing (60) surrounded at least in part by the solar element (58) and guiding the solar element (58) in rotation about the longitudinal axis (X) relative to a fixed structure, and in which the input shaft (54) is driven in rotation by a rotor of the gas generator (38) and the output shaft (56) is movable in rotation jointly with a rotor of the blower.

2. Propulsion system (10) according to claim 1, wherein the bearing (60) is a plain bearing, the coupling system (50) further comprising a lubricant supply device (62) connected to a fixed element (52) and enabling lubricant to be injected at an interface (59) between the plain bearing (60) and the solar element (58).

3. Propulsion system (10) according to claim 1 or 2, wherein the coupling system (50) further comprises at least one fastening device, said fastening device being connected to the satellite carrier.

4. Propulsion system (10) according to claims 2 and 3, wherein the lubricant supply device is integrated into the fastening device.

5. Propulsion system (10) according to claim 4, wherein the fastening device comprises an elongated portion passing through a satellite carrier pivot along an axis parallel to the longitudinal axis (X) and wherein the lubricant supply device comprises a supply conduit extending inside the elongated portion.

6. Propulsion system (10) according to any one of claims 2 to 5, wherein the power supply device (62) comprises a main supply conduit (63) extending inside the plain bearing (60) along the longitudinal axis (X), said main supply conduit (63) being connected to ports opening at the interface (59) by a secondary supply conduit (66).

7. Propulsion system (10) according to any one of claims 1 to 6, wherein the bearing is a cylinder of constant diameter.

8. Propulsion system (10) according to any one of claims 1 to 6, wherein the bearing comprises an upstream portion (76) and a downstream portion (78), the upstream portion and the downstream portion each having an interface with the solar and being connected to each other by a central portion (77) having a radial dimension less than a radial dimension of the upstream portion and the downstream portion.

9. Propulsion system (10) according to any one of claims 1 to 6, wherein the plain bearing (60) comprises an upstream frustoconical portion (80) and a downstream frustoconical portion (82) connected to each other by their ends of smaller diameter in a central part (83), the solar being configured to comprise an interface with both the upstream and downstream frustoconical portions.

10. Propulsion system (10) according to any one of claims 1 to 9, wherein the input shaft (54) is formed of several sections, including a proximal section (86) coupled to the solar (58), a distal section (88) and an intermediate section (87) interposed between the distal (88) and proximal (86) sections, the input shaft (54) further comprising a flexible coupling device (100) comprising a first and a second flexible coupling members (89a, 89b) connecting the intermediate section (87) respectively to the distal section (88) and the proximal section (86), each flexible coupling member (89a, 89b) permitting longitudinal translations and rotations about axes perpendicular to the longitudinal axis.

11. Propulsion system (10) according to claim 9, wherein each flexible coupling member (89a and 89b) comprises a first ring (90a, 90b) connected to the intermediate section (76), a second ring (91a, 91b) connected to one of the distal and proximal sections (88, 86), a crown (92a, 92b) surrounding the first and second rings, a first flexible annular structure (93a, 93b) interposed between the first ring and the crown, and a second structure 16 flexible annular (94a, 94b) interposed between the second ring and the crown.

12. Aircraft comprising a propulsion system according to any one of claims 1 to 11.

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