Turbomachine assembly

Abstract

The present invention relates to a turbomachine assembly comprising: a disc (4); a plurality of blades (5); and a retaining system. Figure for abstract: Fig. 3

Description

Title of the invention: Turbomachine assembly Technical field

[0001] The present disclosure relates to the field of aeronautics. More specifically, the present disclosure relates to a rotor portion of an aeronautical engine, typically the rotor portion of the turbine section of the aeronautical engine. STATE OF THE ART

[0002] The moving blades of a low-pressure turbine stage of an aeronautical engine are generally retained axially on their disk by means of a split ring. In operation, the retaining ring is liable to creep at the level of the slot, which enlarges, thus allowing some of the blades to move axially. Such movements can cause some of the blades to become dislocated, or even released, which requires the engine to be removed, which can be long and costly.

[0003] SUMMARY OF THE PRESENTATION

[0004] An aim of the present disclosure is to improve the mechanical cohesion of the elements of a rotor stage of a turbomachine in order to limit maintenance operations.

[0005] To this end, there is proposed, according to one aspect of the present disclosure, a turbomachine assembly comprising: a disc centered on a longitudinal axis; a plurality of blades mounted in grooves which open at an external periphery of the disc and distributed around the longitudinal axis; and a retaining system cooperating with the disc and the plurality of blades so as to block axial movement of each blade of the plurality of blades relative to the disc, the retaining system comprising: a retaining ring attached to the disc; and a retaining device cooperating with the plurality of blades, the disc and the retaining shroud; wherein the retaining device comprises: a first retaining member which extends circumferentially about the longitudinal axis and which cooperates with the plurality of blades and the disc; and a second retaining member which extends circumferentially about the longitudinal axis and which cooperates with the plurality of blades and the retaining shroud.

[0006] Each of the plurality of blades may include a platform, the plurality of blades being mounted in the grooves such that the plurality of platforms forms an annular wall, each of the plurality of platforms being configured such that an annular groove is formed at an inner surface of the wall. annular, the first retaining member and the second retaining member being inserted into the annular groove.

[0007] Each blade of the plurality of blades may comprise a root mounted in one of the grooves, and a platform, the plurality of blades being mounted in the grooves by their root such that the plurality of platforms forms an annular wall; wherein the retainer may have a radially inner end edge and a radially outer end edge, the radially inner end edge being disposed radially inward of a radially inner end of the root of one of the plurality of blades.

[0008] The first retaining member and the second retaining member may be axially superimposed.

[0009] At least one of the first retaining member and the second retaining member may be a split ring.

[0010] The first retaining member may be a ring split by a first slot and the second retaining member may be a ring split by a second slot, the first slot being positioned offset in the circumferential direction around the longitudinal axis relative to the second slot. The first slot may be located at a first circumferential position about the longitudinal axis and the second slot may be located at a second circumferential position about the longitudinal axis, the first circumferential position being symmetrically opposite the second circumferential position with respect to the longitudinal axis.

[0011] The assembly may further comprise a first anti-rotation system configured to prevent rotation of the first retaining member, relative to the disk and / or the plurality of moving blades, around the longitudinal axis. The first anti-rotation system may comprise a first stop element extending axially upstream, from an upstream surface of the first retaining member, inside a circumferential space delimited by two circumferentially adjacent blades of the plurality of blades, the first stop element being configured to cooperate with one of the two circumferentially adjacent blades so as to prevent rotation of the first retaining member, relative to the disk, around the longitudinal axis.

[0012] The assembly may further comprise a second anti-rotation system configured to prevent rotation of the second retaining member, relative to the retaining shroud and / or the plurality of moving blades, around the longitudinal axis. Each of the plurality of blades may include a platform, the plurality of blades being mounted in the grooves such that the plurality of platforms form an annular wall, each of the plurality of platforms including a a stop member extending radially inwardly from an inner surface of the platform, the stop members defining an annular groove into which the first retaining member and the second retaining member are inserted; wherein the second anti-rotation system may comprise a second stop element extending axially downstream from a downstream surface of the second retaining member; wherein the second stop member may be configured to cooperate with one of the stop members so as to prevent rotation of the second retaining member, relative to the retaining ferrule, about the longitudinal axis.

[0013] According to another aspect, there is provided a turbine comprising a plurality of axially successive stages, each stage comprising a rotor part and a stator part, the rotor part of at least one stage of the plurality of stages comprising an assembly according to the present disclosure.

[0014] According to another aspect, there is provided a turbomachine comprising a fan and a turbine according to the present disclosure, in which the rotor part of each stage of the turbine is integral in rotation with the fan. DESCRIPTION OF FIGURES

[0015] [Fig.l] schematically illustrates an aircraft.

[0016] [Fig.2] is a schematic sectional view of an aeronautical propulsion system.

[0017] [Fig. 3] is a schematic sectional view of a rotor part of a stage of turbine. DETAILED DESCRIPTION

[0018] Aircraft

[0019] An aircraft 100 is a device configured to rise and move in the air, and may, for example, be an airplane, civil or military, or even a helicopter. An aircraft 100 comprises an airframe which, in the case of an airplane, is composed of a fuselage, a wing structure comprising two wings, empennages, flight control surfaces and landing gear.

[0020] Propulsion system

[0021] A propulsion system 1 comprises an engine 2 (or turbomachine) and a nacelle 3, and has a main direction extending along a longitudinal axis XX. The propulsion system 1 is configured to be fixed to the airframe of the aircraft 100, for example under its wings, in the case of an airplane, and this by means of a pylon (or mast). The propulsion system 1 can also be mounted on the wing of the airplane or at the rear of its fuselage, or even be integrated into its fuselage.

[0022] The engine 2 may be a twin-spool, dual-flow, direct-drive ducted turbojet engine, as described below, but may also include a number different in body and / or flow, and / or be another type of turbojet, such as a geared turbojet or a turboprop, with or without afterburner, shrouded or unshrouded.

[0023] Unless otherwise specified, the terms “upstream” and “downstream” are used with reference to the general direction of airflow through the propulsion system 1 in operation. Similarly, an axial direction corresponds to the direction of the longitudinal axis XX and a radial direction is a direction perpendicular to the longitudinal axis XX and intersecting the longitudinal axis XX. Furthermore, an axial plane is a plane containing the longitudinal axis XX and a radial plane is a plane perpendicular to the longitudinal axis XX. A circumference is understood to be a circle belonging to a radial plane and whose center belongs to the longitudinal axis XX. A tangential or circumferential direction is a direction tangent to a circumference: it is perpendicular to the longitudinal axis XX but does not pass through the longitudinal axis XX.Finally, the adjectives "inner" (or "internal") and "outer" (or "external") are used with reference to a radial direction so that the inner part of an element is, in a radial direction, closer to the longitudinal axis XX than the outer part of the same element.

[0024] The engine 2 comprises, from upstream to downstream, a fan 20, a compression section 22, comprising a low pressure compressor 220 and a high pressure compressor 222, a combustion chamber 24 and a turbine section 26, comprising a high pressure turbine 262 and a low pressure turbine 260.

[0025] The compressor section 22 comprises a succession of stages each comprising a wheel of moving blades (rotor) rotating upstream of a wheel of fixed blades (stator). The turbine section 26 also comprises a succession of stages each comprising a wheel of fixed blades (stator) downstream of which a wheel of moving blades (rotor) rotates.

[0026] The fan 20, the rotor part of the low-pressure compressor 220, and the rotor part of the low-pressure turbine 260 are connected to each other by a low-pressure shaft 280 extending along the longitudinal axis XX, so that they are integral in rotation and thus form a low-pressure body (LP body). The rotor part of the high-pressure compressor 222 and the rotor part of the high-pressure turbine 262 are connected to each other by a high-pressure shaft 282 extending along the longitudinal axis XX, so that they are integral in rotation and thus form a high-pressure body (HP body). The low-pressure shaft 280 is generally housed, over a section of its length, in the high-pressure shaft 282 and is coaxial with the high-pressure shaft 172.

[0027] The compression section 22, the combustion chamber 24 and the turbine section 26 are surrounded by a motor casing 23, to which the stator parts are connected. of the low pressure compressor 220, of the high pressure compressor 222, of the high pressure turbine 262 and of the low pressure turbine 260, while the fan 20 is surrounded by a fan casing 25. The engine casing 23 and the fan casing 25 are connected to each other by profiled arms 27 extending radially and forming rectifiers (or OGV for "Outlet Guide Vanes" in English terminology), which are distributed circumferentially all around the longitudinal axis XX. At least some of these arms 27 can be provided structural. The longitudinal axis XX defines the axis of rotation for the fan 20, the rotor parts of the compression section 22 and the rotor parts of the turbine section 26, in other words for the LP body and the HP body, which are each capable of being driven in rotation about the longitudinal axis XX relative to the engine casing 23 and the fan casing 25.

[0028] The nacelle 3 extends radially outside the engine 2, all around the longitudinal axis XX, so as to surround both the fan casing 25 and the engine casing 23, and to define, with a downstream portion of the engine casing 23, a downstream portion of a secondary duct B, the upstream portion of the secondary duct B being defined by the fan casing 25 and an upstream portion of the engine casing 23. The upstream portion of the nacelle 3 further defines an air inlet 29 through which the fan 20 sucks in the air flow circulating through the propulsion system 1. The nacelle 3 is integral with the fan casing 25, and it is attached and fixed to the aircraft 100 by means of the mast.

[0029] In operation, the blower 20 draws in a flow of air, a portion of which, circulating within a primary vein A, is successively compressed within the compression section 22, ignited within the combustion chamber 24 and expanded within the turbine section 26 before being ejected from the propulsion system 1. The expansion within the high-pressure turbine 262 allows the HP body to be driven in rotation, while the expansion within the low-pressure turbine 260 allows the LP body to be driven in rotation. The primary vein A passes right through the engine casing 23. Another portion of the air flow circulates within the secondary vein B which takes an elongated annular shape surrounding the engine casing 23, the air sucked in by the fan 20 being straightened by the rectifiers 27 then ejected from the propulsion system 1. In this way, the propulsion system 1 generates thrust.This thrust can, for example, be used for the benefit of the aircraft 100 on which the propulsion system 1 is attached and fixed.

[0030] Low pressure turbine

[0031] Each wheel 2600 of moving blades of the axially successive stages of the low pressure turbine 260 comprises a disc 4 and a plurality of moving blades 5.

[0032] Disc

[0033] The disc 4 is centered on the longitudinal axis XX. It has an internal edge of limiting an axial bore, also centered on the longitudinal axis XX, and through which the low pressure shaft 280 extends. The disc 4 further has an outer edge delimiting a plurality of axial cells 40 distributed around the longitudinal axis XX. The cells thus form grooves 40 which open at the outer periphery of the disc 4. Each of the grooves 40 is configured to ensure the fixing, in a removable manner, of one of the moving blades 5 on the disc 4. In this regard, each groove 40 is open onto the primary vein A and may, in addition, have any shape suitable for the fixing of a moving blade 5, typically a dovetail or fir tree root shape, with at least one, or even several, lobes.

[0034] Moving blades

[0035] Each moving blade 5 comprises a foot 50, a stilt 51, a platform 52, a blade 53 and may comprise a heel.

[0036] The root 50 allows the moving blade 5 to be mounted on the disc 4, preferably in axial translation, by cooperation with the disc 4, and more precisely with a groove 40, the moving blade 5 being mounted in a groove 40 by its root 50, so that the moving blades 5 are distributed around the longitudinal axis XX at the external edge of the disc 4. In this respect, the root 50 may have a shape complementary to that of the groove 40.

[0037] The platform 52 of a moving blade 5 is configured to cooperate with the platforms 52 of the moving blades 5 which are circumferentially adjacent to it so that the plurality of platforms 52 forms an annular wall delimiting an internal portion of the primary vein A. Furthermore, each of the platforms 52 is configured so that an annular groove 520 is formed at an internal surface of the annular wall. Typically, each platform 52 may have a circumferential groove 5200 at its inner surface, which cooperates with the circumferential grooves of the circumferentially adjacent platforms 52 to form the annular groove 520. Furthermore, at least one of the platforms 52, preferably each of them, comprises a stop member 521, typically in the form of a stud (or pin), extending radially inward from an inner surface of the platform 52.Preferably, the stop member 521 is positioned downstream of the circumferential groove 5200. Furthermore, a wall of the stop member 521 may extend in the radial extension of a wall of the circumferential groove 5200. In addition, the stop member 521 may have a circumferential dimension strictly less than the circumferential extension of the circumferential groove 5200 and / or be centered, or not, in a circumferential direction, on the platform 52. The stop member 521 may also consist of a hook forming the circumferential groove 5200, that is to say delimiting the circumferential groove 5200. When . each platform 52 comprises a stop member 521, the plurality of stop members 521 can be aligned in a circumferential direction, within the same axial plane, so as to form an annular stop structure which delimits, where appropriate, the annular groove 520.

[0038] The stilt 51 of a moving blade 5 connects its root 50 to its platform 52. In this way, an inter-stilt space is delimited, between two circumferentially adjacent moving blades 5, radially by the platforms 52 of the moving blades 5 and the outer edge of the disc 4, and circumferentially by the stilts 51 of the moving blades 5. Furthermore, the inter-stilt space is axially open. A plurality of inter-stilt spaces is thus formed, the inter-stilt spaces being distributed around the longitudinal axis XX.

[0039] The blade 53 is connected to the platform 52 and extends within the primary vein A. The blade 53 has an aerodynamic profile and has, in this respect, a leading edge on which the gases strike first when they encounter the moving blade wheel 2600, a trailing edge axially opposite the leading edge, and an end radially opposite the platform 52. The blade 53 interacts with the gases flowing within the primary vein A to drive the disk 4 in rotation about the longitudinal axis XX. To do this, the blade 53 extends within the primary vein A with a certain incidence relative to the main direction 53 of flow of the gases.

[0040] When present, the heel extends from the end of the blade 53, being fixed there removably, or not, or being in one piece with the blade 53. The heel ensures the sealing of the primary vein A by limiting gas leaks at the interface between the mobile blade wheel 2600 and the low-pressure turbine casing 260. In this respect, the heel carries sealing lips intended to cooperate with an abradable extending from the casing of the low-pressure turbine 260.

[0041] Fixed blades

[0042] The wheel 2601 of fixed blades comprises a plurality of fixed blades 6, each fixed to the casing of the low-pressure turbine 260, being distributed around the longitudinal axis XX. In the same way as for the moving blades 5, the fixed blades 6 each comprise a blade 63 extending within the primary vein A and whose aerodynamic profile makes it possible to straighten the gases after their interaction with the blades 53 of the moving blades 5. In addition, each fixed blade 6 has an end, radially opposite the fixing of the fixed blade on the casing of the low-pressure turbine 260, from which a sealing element 60 formed by an abradable block extends radially inwards, the abradable block being made up of cells to allow its abradability during possible contact between wipers 70 and the sealing element 60.

[0043] Sealing disc

[0044] The wheels 2600 of moving blades of the successive stages of the low-pressure turbine 260 are connected to each other, at least one of them being connected to the low-pressure shaft 280. Typically, the discs 4 of two wheels 2600 of successive moving blades each comprise a ferrule 41, the ferrules 41 being fixed to each other, for example by bolting.

[0045] Furthermore, a sealing disc 7 is fixed to the ferrules 41, typically at the bolted connection by which the ferrules 41 are fixed together. The sealing disc 7 is positioned axially at the wheel 2601 of moving blades. The sealing disc 7 comprises the wipers 70 which extend radially opposite the abradables 60 of the wheel 2601 of fixed blades so as to prevent air circulation at the ends of the fixed blades 6. The sealing disc 7 forms, with the wheel 2600 of moving blades, a rotor stage of the low-pressure turbine 260. The sealing disc 7 further comprises a retaining ferrule 71, preferably annular. The retaining ferrule 71 may be integral with the sealing disc 7 or be removably fixed to the sealing disc 7.The retaining ring 71 is fixed to each of the discs 4 of the movable blade wheels 2600 between which the sealing disc 7 is fixed, since it is rotationally integral with the sealing disc 7.

[0046] Restraint system

[0047] To block an axial movement of each moving blade 5 relative to the disk 4, a retaining system cooperating with the disk 4 and the plurality of moving blades 5 is provided. In addition to the retaining shroud 71, this retaining system comprises a retaining device 8, preferably annular. Preferably, the retaining system is arranged downstream of the wheel 2600 of moving blades, so as to block an axial movement of the moving blades 5 downstream. If necessary, another retaining system may be provided to block an axial movement of the moving blades 5 upstream.

[0048] The retaining device 8 cooperates with both the plurality of moving blades 5, the disc 4 and the retaining shroud 71. More specifically, the retaining shroud 71 keeps the retaining device 8 pressed against the disc 4 and the plurality of moving blades 5. In this respect, the retaining device 8 has a radial dimension, defined as a distance, preferably the smallest distance, between a radially inner end edge and a radially outer end edge of the retaining device 8, which is greater than a distance, preferably the largest distance, separating an inner surface of the annular wall formed by the platforms 52 of the moving blades 5, and a radially inner end of the root 50 of a moving blade 5 of the plurality of moving blades 5, preferably the one which is closest to the longitudinal axis XX.In this way, the radially inner end edge of the retaining device 8 is arranged radially inwardly with respect to a radially inner end of the root 50 of the moving blade 5 of the plurality of moving blades 5, preferably the one which is the . closer to the longitudinal axis XX. In other words, the retaining device 8 masks the radial extension of at least the inter-stilt spaces and the grooves 40, which ensures the prevention of axial movement of the roots 50 of the moving blades 5 relative to the grooves 40. In addition, this makes it possible to maintain the rigidity of the retaining device 8, by avoiding axial twisting of the retaining device 8, at its radially external end, in the event of differential thermal expansion between different radial portions of the moving blades 5 (also called the phenomenon of “thermal creep” towards the upstream of the moving blades 5).

[0049] The retaining device 8 comprises a first retaining member 81 and a second retaining member 82. Each of the first retaining member 81 and the second retaining member 82 extends circumferentially around the longitudinal axis XX, preferably all around the longitudinal axis XX. In other words, each of the first retaining member 81 and the second retaining member 82 is preferably annular. The use of two annular retaining members 81, 82 makes it possible to ensure the retention of the moving blades 5 despite the fining of one of the two annular retaining members 81, 82.

[0050] The first retaining member 81 cooperates with the plurality of moving blades 5 and the disc 4. As a result, the first retaining member 81 is arranged upstream of the second retaining member 82. Preferably, the first retaining member 81 cooperates with the annular groove 520 by being inserted into the annular groove 520, typically with an external portion of the first retaining member 81 which is housed inside the annular groove 520. Housing an external portion of the first retaining member 81 in the annular groove 520 provides stable support of the first retaining member 81 on the plurality of moving blades 5. The first retaining member 81 may be a ring split by a second slot, which simplifies its assembly, in particular within the annular groove 520, by radial deformation. What is more, the number of parts of the retaining system is thus more limited, which reduces the risk of assembly errors. In addition, under the effect of the centrifugal load during operation, the ring deforms radially in a uniform manner, which guarantees uniform support at the bottom of the annular groove 520, if necessary. Alternatively, the first retaining member 81 may comprise, or even consist of, a plurality of ring sectors, for example as many ring sectors as there are moving blades 5, each ring sector comprising an external portion housed in a circumferential groove 5200 of a platform 52 of one of the moving blades 5. Thus, the unbalance associated with the presence of the first retaining member 81 can be more finely controlled. Advantageously, the ring sectors are arranged in a staggered pattern in a circumferential direction.

[0051] A first anti-rotation system may be provided to prevent rotation of the first retaining member 81 relative to the disc 4 and / or the plurality of moving blades 5, around the longitudinal axis XX. In this way, wear of the first retaining member 81, the moving blades 5 and / or the disc 4, is reduced. Preferably, the first anti-rotation system comprises a first stop element 91, typically a stud (or pin), extending axially upstream, from an upstream surface of the first retaining member 81, inside a circumferential space delimited by two circumferentially adjacent moving blades 5, for example the inter-stilt space. The first stop element 91 is configured to cooperate with one of the two circumferentially adjacent moving blades 5, preferably the stilt 51 of one of the two circumferentially adjacent moving blades 5, so as to prevent rotation of the first retaining member 81, relative to the disc 4 and / or the plurality of moving blades 5, around the longitudinal axis XX.More specifically, in the event of relative circumferential movement between the first retaining member 81 and one of the disk 4 or the plurality of moving blades 5, the first stop element 91 is provided to come into abutment against one or other of the stilts 51 of the moving blades 5 which are circumferentially adjacent to it, so as to stop this relative circumferential movement. Advantageously, a circumferential dimension of the first stop element 91 is less than a circumferential dimension of the circumferential space delimited by two circumferentially adjacent moving blades 5, in order to allow circumferential flexibility of the retaining system, in particular during assembly. A plurality of first stop elements 91 may be provided by being distributed around the longitudinal axis XX, which may make it possible to control the imbalance that the presence of a single stop element could introduce. In addition, this makes it possible to distribute the circumferential force for achieving the rotational stop, between all the first stop elements 91. What is more, the wear of the first retaining member 81, the moving blades 5 and / or the disc 4, is all the more reduced. Where appropriate, each of the plurality of first stop elements 91 extends within one of the plurality of inter-stilt spaces. The first stop element 91 may be integral with the first retaining member 81, for example by being integral with the first retaining member 81, or may be removably attached to the first retaining member 81. Providing a plurality of removable first stop elements 91 on the first retaining member 81 makes it possible to adjust the imbalance associated with the first retaining member 81 more precisely. Advantageously, the first stop element 91 can allow for keying during assembly of the first retaining member 81.

[0052] The second retaining member 82 cooperates with the plurality of moving blades 5 and the retaining ring 71. As a result, the second retaining member 82 is arranged downstream of the first retaining member 81. Preferably, the second retaining member 82 cooperates with the annular groove 520 by being inserted into the annular groove 520, typically with an external portion of the second retaining member 82 which is housed inside the annular groove 520. Where appropriate, the stop members 521 form an axial stop for the second retaining member 82. Housing an external portion of the second retaining member 82 in the annular groove 520 provides stable support for the second retaining member 82 on the plurality of moving blades 5. The second retaining member 82 may be a ring split by a first slot, which simplifies its assembly, in particular within the annular groove 520, by radial deformation. What is more, the number of parts of the retaining system is thus more limited, which reduces the risk of assembly errors. In addition, under the effect of the centrifugal load during operation, the ring deforms radially in a uniform manner, which guarantees uniform support at the bottom of the annular groove 520, if necessary. Alternatively, the second retaining member 82 may comprise, or even consist of, a plurality of ring sectors, for example as many ring sectors as there are moving blades 5, each ring sector comprising an external portion housed in a circumferential groove 5200 of a platform 52 of one of the moving blades 5. Thus, the unbalance associated with the presence of the second retaining member 82 can be more finely controlled. Advantageously, the ring sectors are arranged in a staggered pattern in a circumferential direction.

[0053] A second anti-rotation system may be provided to prevent rotation of the second retaining member 82 relative to the retaining shroud 71 and / or the plurality of moving blades 5, around the longitudinal axis XX. In this way, wear of the second retaining member 82, the moving blades 5 and / or the retaining shroud 71, is reduced. Preferably, the second anti-rotation system comprises a second stop element 92, typically a stud (or pin), extending axially downstream, from a downstream surface of the second retaining member 82. The second stop element 92 is configured to cooperate with at least one of the stop members 521 of one of the two moving blades 5 which are circumferentially adjacent to it, so as to prevent the rotation of the second retaining member 82, relative to the retaining shroud 71 and / or to the plurality of moving blades 5, around the longitudinal axis XX. More specifically, in the event of relative circumferential movement between the second retaining member 82 and one of the retaining shroud 71 or the plurality of moving blades 5, the second stop element 92 is provided to come into abutment against one or other of the stop members 521 of the moving blades 5 which are circumferentially adjacent to it, so as to stop this relative circumferential movement. Advantageously, a circumferential dimension of the second stop element 92 is less than a distance separating the stop members 521 of two circumferentially adjacent platforms 52 of mobile blades 5, in order to allow circumferential flexibility of the retaining system, in particular during assembly. A plurality of second stop elements 92 may be provided by being distributed around the longitudinal axis XX, which limits the imbalance that the presence of a single stop element could introduce. In addition, this makes it possible to distribute the circumferential force for achieving the rotational stop, between all the second stop elements 92. What is more, the wear of the second retaining member 82, of the moving blades 5 and / or of the retaining shroud 71, is all the more reduced. Where appropriate, each of the plurality of second stop elements 92 extends between two of the plurality of stop members 521 of the platforms 52 of the moving blades 5. The second stop element 92 may be integral with the second retaining member 82, for example by being integral with the second retaining member 82, or may be removably fixed to the second retaining member 82. Providing a plurality of removable stop elements makes it possible to adjust the imbalance associated with the second retaining member 82 more precisely. Advantageously, the second stop element 92 can allow for keying during assembly of the second retaining member 82.

[0054] Advantageously, the first retaining member 81 and the second retaining member 82 are axially superimposed, that is to say that at least a portion of the downstream surface of the first retaining member 81 is in contact with at least a portion of the upstream surface of the second retaining member 82, the contact being kept tight by the presence of the retaining ferrule 71 as well as, to a certain extent, the edges of the annular groove 520, if applicable. In this way, the axial forces exerted by the moving blades 5 can be fully transmitted to the retaining ferrule 71. In addition, one of the first annular retaining member 81 and the second retaining member 82 can participate in maintaining the other of the first retaining member 81 and the second retaining member 82 in circumferential position, by friction of their surfaces kept in contact.

[0055] In a variant, a radial dimension of the first retaining member 81 may be identical to a radial dimension of the second retaining member 82, so that their external edges and their internal edges are flush. This makes it possible to limit the size and the unbalance of the retaining device 8.

[0056] In one variant, each of the first retaining member 81 and the second retaining member 82 is a split ring, and the first slot of the first retaining member 81 is positioned offset in the circumferential direction around the axis longitudinal XX relative to the second slot of the second retaining member 82. In other words, the first slot is positioned at a distance from the second slot, in a circumferential direction. In this way, in the event of fining of one of the annular members at its slot, the associated opening does not cause freedom of movement of the root 50 of the moving blade 5 which faces it, since the other of the annular members is not split, at the same circumferential position, and therefore ensures axial retention. In addition, the opening, by fining, of the slot of one of the two annular retaining members 81, 82 causes, by circumferential friction, the closing of the slot of the other of the two annular retaining members 81, 82, which mechanically guarantees the systematic presence of axial retention of the moving blades 5. Advantageously, at least one of the first rotation stop system and the second rotation stop system makes it possible to prevent the slot of the first retaining member 81 from being in the same circumferential position as the slot of the second retaining member 82. Preferably, the slot of the first retaining member 81 is located at a first circumferential position around the longitudinal axis XX and the slot of the second retaining member 82 is located at a second circumferential position around the longitudinal axis XX, and the first circumferential position is symmetrically opposite the second circumferential position with respect to the longitudinal axis XX. Thus, the imbalance associated with the presence of the slots is limited.

Claims

Claims

1. A turbomachine assembly (2) comprising: a disk (4) centered on a longitudinal axis (XX); a plurality of blades (5) mounted in grooves (40) which open at an external periphery of the disk (4) and distributed around the longitudinal axis (XX); and a retaining system cooperating with the disk (4) and the plurality of blades (5) so as to block an axial movement of each blade (5) of the plurality of blades (5) relative to the disk (4), the retaining system comprising: a retaining shroud (71) fixed to the disk (4); and a retaining device (8) cooperating with the plurality of blades (5), the disk (4) and the retaining shroud (71); wherein the retaining device (8) comprises: a first retaining member (81) which extends circumferentially around the longitudinal axis (XX) and which cooperates with the plurality of blades (5) and the disc (4);and a second retaining member (82) which extends circumferentially around the longitudinal axis (XX) and which cooperates with the plurality of blades (5) and the retaining shroud (71).;

2. An assembly according to claim 1, wherein each blade (5) of the plurality of blades (5) comprises a platform (52), the plurality of blades (5) being mounted in the grooves (40) such that the plurality of platforms (52) forms an annular wall, each platform (52) of the plurality of platforms (52) being configured such that an annular groove (520) is formed at an inner surface of the annular wall, the first retaining member (81) and the second retaining member (82) being inserted into the annular groove (520).

3. An assembly according to any one of claims 1 and 2, wherein each blade (5) of the plurality of blades (5) comprises a root (50) mounted in one of the grooves (40), and a platform (52), the plurality of blades (5) being mounted in the grooves (40) by their root (50) so that the plurality of platforms (52) forms an annular wall; wherein the retaining device (8) has a radially inner end edge and a radially outer end edge, the radially inner end edge being arranged radially inwardly with respect to a radially inner end of the root (50) of a blade (5) of the plurality of blades (5).

4. An assembly according to any one of claims 1 to 3, wherein the first retaining member (81) and the second retaining member (82) are axially superimposed.

5. An assembly according to any one of claims 1 to 4, wherein at least one of the first retaining member (81) and the second retaining member (82) is a split ring.

6. An assembly according to any one of claims 1 to 5, wherein the first retaining member (81) is a ring split by a first slot and the second retaining member (82) is a ring split by a second slot, and wherein the first slot is positioned offset in the circumferential direction around the longitudinal axis (XX) relative to the second slot.

7. An assembly according to claim 6, wherein the first slot is located at a first circumferential position about the longitudinal axis (XX) and the second slot is located at a second circumferential position about the longitudinal axis (XX), the first circumferential position being symmetrically opposite the second circumferential position with respect to the longitudinal axis (XX).

8. Assembly according to any one of claims 1 to 7, further comprising a first anti-rotation system configured to prevent rotation of the first retaining member (81), relative to the disc (4) and / or the plurality of movable blades (5), around the longitudinal axis (XX).

9. An assembly according to claim 8, wherein the first anti-rotation system comprises a first stop element (91) extending axially upstream, from an upstream surface of the first retaining member (81), inside a circumferential space delimited by two circumferentially adjacent blades (5) of the plurality of blades (5), the first stop element (91) being configured to cooperate with one of the two circumferentially adjacent blades (5) so as to prevent rotation of the first retaining member (81), relative to the disc (4), around the longitudinal axis (XX).

10. Assembly according to any one of claims 1 to 9, further comprising a second anti-rotation system configured to prevent rotation of the second retaining member (82), relative to the retaining shroud (71) and / or to the plurality of movable blades (5), around the longitudinal axis (XX).

11. An assembly according to claim 10, wherein each blade (5) of the plurality of blades (5) comprises a platform (52), the plurality of blades (5) being mounted in the grooves (40) such that the plurality of platforms (52) forms an annular wall, each platform (52) of the plurality of platforms (52) comprising a stop member (521) extending radially inward from an inner surface of the platform (52), the stop members (521) defining an annular groove (520) into which the first retaining member (81) and the second retaining member (82) are inserted; wherein the second anti-rotation system comprises a second stop element (92) extending axially downstream from a downstream surface of the second retaining member (82); wherein the second stop element (92) is configured to cooperate with one of the stop members (521) so as to prevent rotation of the second retaining member (82), relative to the retaining ferrule (71), around the longitudinal axis (XX).

12. A turbine (260) comprising a plurality of axially successive stages, each stage comprising a rotor portion and a stator portion, the rotor portion of at least one of the plurality of stages comprising an assembly according to any one of claims 1 to 11.

13. Turbomachine (2) comprising a fan (20) and a turbine (260) according to claim 12, in which the rotor part of each stage of the turbine (260) is rotationally integral with the fan (20).

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