FAN ROTOR ASSEMBLY FOR TURBOMACHINE

Abstract

A fan rotor assembly (10) for a turbomachine, the rotor assembly (10) comprising an inlet cone (14) and a fan disc (12) arranged around a longitudinal axis (A) of the rotor assembly (10), wherein the inlet cone (14) comprises a first end portion (27) and the fan disc (12) comprises a first complementary end portion (25), the first end portion (27) and the first complementary end portion (25) being substantially annular, wherein said first end portion (27) and the first complementary end portion (25) are mounted tightly together. Abstract figure: Figure 1

Description

Title of the invention: ROTOR FAN ASSEMBLY FOR TURBOMACHINE Technical field

[0001] The present disclosure relates to the field of fan rotor assemblies for turbomachines. Prior art

[0002] In a known manner, an aircraft turbomachine sucks in a flow of air at its upstream end which is then exhaled at high speed at its downstream end, thus creating the thrust necessary to move the aircraft forward.

[0003] In order to suck in said air flow, the upstream end of the turbomachine comprises an air inlet provided with an inlet cone and a fan.

[0004] The fan comprises a plurality of blades which are distributed circumferentially on a fan disc. The fan disc is mounted on a compressor shaft, in particular a low-pressure compressor (or "LP compressor"), which is rotated about its longitudinal axis by a turbine of the turbomachine. The fan disc and its blades then rotate integrally with the compressor shaft, which promotes the suction of the air flow.

[0005] The inlet cone is installed in the air inlet longitudinally in front of the fan, preferably centered on the longitudinal axis of the compressor shaft. A conical outer surface of the inlet cone forms an airflow flow surface that allows a portion of the airflow entering the turbomachine to be diverted toward the fan blades.

[0006] Conventionally, the inlet cone and the fan disk are connected to each other by a ferrule, called the front ferrule. The front ferrule is located longitudinally between the inlet cone and the fan disk. A plurality of connecting means, such as screws, are used to connect the front ferrule to the inlet cone on the one hand, and to the fan disk on the other hand. The presence of the ferrule therefore requires the use of an additional serial screw, which complicates the manufacture of the turbomachine (large number of parts and long manufacturing time, among other things) and increases the risks of failure to be corrected during maintenance.

[0007] Furthermore, the use of the front shroud to connect the inlet cone and the fan disc together makes the assembly of the turbomachine more complex, both in terms of assembly cost, assembly time and manufacturing of the various parts. For example, in order to connect the front shroud to the inlet cone and the fan disc with screws, it is necessary to provide holes for fixing these screws in the ferrule, the inlet cone and the fan disc, and it is necessary that these holes be placed in precise positions. Therefore, it is sufficient that there is a certain deviation in the position of one of these holes for the assembly of the inlet cone-front ferrule-fan disc assembly not to be possible from the manufactured parts. Alternatively, the stock of each part would have to be managed more finely according to the pairings known as possible, which makes the assembly and quality control processes more complex and more expensive.

[0008] In addition, the front shroud being arranged longitudinally between the inlet cone and the fan disc, an additional aerodynamic step, a source of pressure losses, is formed along the flow path followed by the flow of sucked air.

[0009] On the other hand, conventionally the blades are held in the fan disc by small and numerous locks. The locks therefore constitute a source of assembly complexity and a multiplicity of maintenance checks.

[0010] It is therefore necessary to develop a simplified connection architecture between the fan disc and the front cone of the turbomachine, so as to improve its manufacturability. Summary

[0011] The present disclosure aims to overcome at least some of the drawbacks detailed above.

[0012] For this purpose, a fan rotor assembly for a turbomachine is proposed, the rotor assembly comprising an inlet cone and a fan disc arranged around a longitudinal axis of the rotor assembly, in which the inlet cone comprises a first end portion and the fan disc comprises a first complementary end portion, the first end portion and the first complementary end portion being substantially annular, in which said first end portion and the first complementary end portion are mounted tightly together.

[0013] Thus, the inlet cone and the fan disk are directly connected to each other, which eliminates the need to use the front shroud. Manufacturing the rotor assembly is thus faster, less expensive and simpler. Similarly, by eliminating the front shroud, the rotor assembly proposed herein presents less risk of obtaining unusable parts, defective assembly, or failure in service. For example, eliminating the front shroud avoids having to machine holes for fixing the front shroud on the inlet cone or on the fan disk.

[0014] Furthermore, by eliminating the front ferrule, the weight of the rotor assembly is also reduced.

[0015] In addition, the inlet cone and the fan disc being mounted tightly together, the additional aerodynamic step constituted by the shroud is eliminated. before the prior art, thus reducing the load losses in the rotor assembly.

[0016] Finally, the tight fitting of the first end portion and the first complementary end portion makes it possible to maintain the inlet cone radially in position relative to the fan disc. The tight fitting of the first end portion and the first complementary end portion also contributes to maintaining the inlet cone axially in position relative to the fan disc.

[0017] In the present text, by "longitudinal" or "axial" is meant in a direction substantially parallel to the longitudinal axis of the rotor assembly, while by "radial" or "transverse" is meant in a direction substantially perpendicular to the longitudinal axis of the rotor assembly.

[0018] The tight fit between the first end portion and the first complementary end portion can be achieved by shrink fitting, which makes it possible to achieve centering between the fan disc and the nose cone with reduced radial clearance, thereby reducing the aerodynamic steps of the rotor assembly.

[0019] By rotor assembly is meant that each of the parts which form this assembly can be driven in rotation around the longitudinal axis of the assembly, whether directly or thanks to connections with other parts.

[0020] The inlet cone may further comprise a second end portion having a substantially conical shape that flares from upstream to downstream. In this text, the terms "upstream" and "downstream" are to be interpreted in relation to the direction of flow of an air flow drawn into the turbomachine and passing longitudinally through the turbomachine between its two ends.

[0021] The downstream end of the second end portion of the inlet cone may have a cross-section greater than the cross-section of the first end portion of the cone. A substantially radially extending annular wall may connect the first end portion of the inlet cone, in particular an upstream end of this first end portion, to the downstream end of the second end portion of the inlet cone. The cross-section of the downstream end of the second end portion of the inlet cone may also be greater than the cross-section of the complementary first end portion of the fan disk.

[0022] In this text, “cross-section” means a section included in a plane extending transversely.

[0023] The fan disc may have an annular shape comprising a longitudinally extending cavity delimited radially by a radially inner surface of the fan disc. The fan disc may thus be mounted around a compressor shaft, in particular a low-pressure compressor.

[0024] In this text, by “annular” is meant any shape comprising a closed perimeter which delimits a cavity, whatever its section.

[0025] According to one aspect, said first end portion may be clamped in said complementary end portion.

[0026] The inlet cone is thus tightly mounted in the fan disc. For this purpose, a cross-section of the first end portion may be substantially equal in shape and dimension to a cross-section of the complementary first end portion.

[0027] By tightly fitting the inlet cone in the fan disc, a centering of the inlet cone in the fan disc is achieved, thereby reducing aerodynamic steps. As previously indicated, the tight fitting allows the inlet cone to be held radially in position relative to the fan disc, and also helps to maintain the axial position of the inlet cone relative to the fan disc.

[0028] When the tight fit of the inlet cone in the fan disc is achieved by shrink fitting, this can be achieved by heating the complementary first end portion, which expands, and then inserting the first end portion into the expanded complementary first end portion. Then, the complementary first end portion can be allowed to cool, which causes it to contract so as to squeeze the first end portion. Alternatively, shrink fitting can be achieved by cooling the first end portion, which shrinks, and then inserting it into the complementary first end portion. In this case, as the temperature of the first end portion increases, it expands and squeezes into the complementary first end portion.

[0029] According to one aspect, said first end portion of the inlet cone may comprise at least one fixing hole, said first complementary end portion of the fan disc may comprise at least one complementary fixing hole, the at least one fixing hole may be arranged radially opposite the at least one complementary fixing hole, a member for connecting the fan disc to the inlet cone may be installed in the at least one first fixing hole and the at least one first complementary fixing hole.

[0030] The at least one fixing hole being radially opposite the at least one complementary fixing hole, the connecting member can extend for example substantially radially in a radial cavity formed by the at least one fixing hole and the at least one complementary fixing hole which are radially opposite each other. Also, thanks to the connecting member, the axial retention of the inlet cone relative to the fan disc is improved.

[0031] The connecting member may be a screw or a bolt, among others.

[0032] According to one example, the first hole and the first complementary hole are holes crossings having a substantially cylindrical shape.

[0033] According to one aspect, a nut may be crimped into said at least one fixing hole and / or into said at least one complementary fixing hole.

[0034] The nut allows the connecting member to be held in position inside the fixing hole and the complementary fixing hole.

[0035] The nut may be an independent part connected to a wall of the at least one fixing hole and / or the at least one complementary fixing hole. The nut may alternatively be made in one piece with the wall of the at least one fixing hole and / or the at least one complementary fixing hole.

[0036] In some cases, a first nut may be crimped into the at least one fastening hole and a second nut may be crimped into the at least one complementary fastening hole.

[0037] According to one aspect, said first end portion may comprise an annular row of fixing holes distributed around the longitudinal axis of the rotor assembly, the first complementary end portion being able to comprise an annular row of complementary fixing holes distributed around the longitudinal axis of the rotor assembly, each fixing hole being able to be radially opposite a respective complementary fixing hole.

[0038] A respective connecting member can therefore be installed substantially radially in the radial cavity formed by each fixing hole and each complementary fixing hole which are radially opposite each other. The axial retention of the inlet cone relative to the fan disc is thus improved.

[0039] The fixing holes and the complementary fixing holes may be distributed regularly around the longitudinal axis of the rotor assembly. Alternatively, the fixing holes and the complementary fixing holes may be distributed irregularly around the longitudinal axis of the rotor assembly.

[0040] According to one aspect, a radially external surface of the fan disk may comprise a plurality of cells distributed around the longitudinal axis of the rotor assembly, the rotor assembly further comprising a plurality of blades, each blade comprising a blade root engaged in one of said cells, the blade root comprising an axial stop hook comprising a projecting portion mounted axially fitted in a housing of the fan disk.

[0041] The projecting part of the axial stop hook being mounted axially adjusted in the housing of the disc, axial displacements of the blade root are avoided. The blade root is thus retained in the rotor assembly from a retention system directly integrated in the blade, without the need to use additional parts, such as locks, which reduces the number of parts to be machined and assembled. The manufacture of the rotor assembly is thus simpler, faster and less expensive. In addition, the risk of manufacturing or assembly errors, such as forgetting to install certain locks, is diminished.

[0042] It is noted that the axial stop hook integrated into the blade makes it possible to retain the blade root in the rotor assembly, in particular in the fan disk, even in the event of critical events endangering the entire blade, such as the ingestion of a bird or the breakage of the blade.

[0043] In this text, the term “adjusted” may be understood as a synonym for the terms “immobilized” or “blocked”, among others.

[0044] The axial stop hook extends for example in a plane substantially perpendicular to the axial direction.

[0045] The projecting portion of the axial stop hook projects, for example, in a direction substantially perpendicular to a plane comprising the axial direction and the radial direction. Each cell forms, for example, a groove on the radially outer surface of the fan disc. Each cell may be rectilinear and may extend substantially axially along the entire length of the fan disc.

[0046] When the cross-section of the downstream end of the second end portion of the inlet cone is greater than the cross-section of the complementary first end portion of the fan disc, the annular wall connecting the first end portion and the second end portion of the inlet cone may form a wall delimiting an upstream longitudinal end of each cell.

[0047] The blade root is part of a respective blade which may further comprise a stilt and a blade. The stilt may be arranged radially between the blade root and the blade. According to a non-limiting example, the blade root, stilt and the blade are made from a single piece.

[0048] Each blade may be made of metallic or composite material, for example 3D woven composite.

[0049] The shape of each blade root may be complementary to the shape of each cell or adapted to introduce the blade root into the respective cell. For example, each blade root may have a fir tree or dovetail shape.

[0050] The housing is for example included in a side wall of one of the cells. Each cell may comprise two side walls. Preferably, each side wall of each cell comprises a respective housing.

[0051] Each housing may have a portion having an axial dimension substantially equal to an axial dimension of the projecting portion of the axial stop hook. Thus, axially adjusted mounting of the projecting portion of the hook is possible.

[0052] Each housing forms in particular a groove which is open, preferably over its entire extension, in the respective cell.

[0053] According to a non-limiting example, the housing comprises a first part extending substantially parallel to said longitudinal axis from an upstream end of the fan disc and a second part extending substantially transversely to said first part. The housing thus has an L-shape. The projecting part of the axial retention hook can in particular be mounted axially adjusted in the second part of the housing. For this purpose, the blade root can be introduced into the respective cell, with the blade being oriented from its root to its blade in the direction of the gravity force. In such a case, the projecting part of the axial retaining hook is initially engaged in the first part of the housing. The blade root can then be moved axially in the cell, which causes the projecting part of the axial retaining hook to be axially moved in the first part of the housing.Once the projecting portion of the axial stop hook is radially opposite the second portion, the force of gravity would cause the blade root to move radially in the respective cell. The blade root would therefore move radially away from the bottom wall of the cell, and the projecting portion of the axial stop hook would be engaged in the second portion of the housing, where it can be axially retained in a snug manner.

[0054] It is noted that the axial dimension of the projecting portion of the axial stop hook and of the second part of the housing may be chosen so as to ensure that the projecting portion of the axial stop hook is fitted tightly in the second part of the housing.

[0055] According to one aspect, the radially outer surface of the fan disc comprises a plurality of teeth, each tooth being arranged between two successive cells, the at least one complementary fixing hole extending substantially radially through a respective tooth of the fan disc.

[0056] Since the root of each blade is installed in one of the cells, the complementary fixing hole remains accessible after the blades have been installed on the fan disc. It is thus possible to connect the fan disc and the inlet cone via the connecting member after the blades have been installed on the fan disc. The cone can thus have a sufficient cross-section to longitudinally close each cell, which improves the axial retention of each blade.

[0057] As indicated, the cells can be distributed regularly around the longitudinal axis of the rotor assembly. Thus, each cell can define with the neighboring cell one of the teeth. Each cell can thus be delimited between two successive teeth. Each tooth extends substantially axially along the entire length of the fan disk.

[0058] The side walls of each alveolus correspond in particular to the wall of each tooth which delimits the groove formed by each alveolus.

[0059] The housing of the disc in which the projecting part of the hook of the blade root is retained axially can for example be formed in side walls of each tooth of the fan disc which delimit each cell.

[0060] According to one aspect, the rotor assembly further comprises at least one blade platform, the at least one platform comprising at least one radial retention hole or at least one radial retention notch, said hole or notch being arranged radially opposite said complementary fixing hole, said connecting member passing radially through said hole or notch.

[0061] Each platform is thus fixed to the fan disc by means of the same connecting member which connects the front cone and the fan disc. Each platform is therefore held radially in position on the fan disc, whether the turbomachine is rotating or stationary.

[0062] From an aerodynamic point of view, each platform has the function of defining the flow path of the air flow. In addition, the platform is advantageously capable of resisting significant forces without deforming and while remaining integral with the fan disc which carries them.

[0063] Each platform may be an integral part. In other cases, each platform may be integrally formed with each blade. In such cases, each platform may be integrally formed with a respective blade. Thus, each platform may be integrated with a respective blade, instead of forming a unitary part integral with the rotor assembly. The manufacture of the rotor assembly is thus simplified.

[0064] Each platform is mounted in the vicinity of the foot of the respective blade.

[0065] Each platform can be mounted in the gap between two neighboring blades. In this case, a first platform is adjacent to the intrados side of the blade, and a second platform distinct from the first is adjacent to the extrados side of the blade. Alternatively, each platform is arranged around the intrados and the extrados of the respective blade. For this purpose, each platform comprises a groove capable of introducing each blade into the respective platform. Thus, the interval between two neighboring blades is occupied by half of two neighboring platforms. Such a configuration is called herein "sock configuration".

[0066] Each blade platform may have a first end portion and a second axially opposite end portion. The at least one radial retention hole or the at least one radial retention notch may be included in the first end portion.

[0067] The second end portion of each platform may be in contact with a rotating spacer of the rotor assembly. In particular, the contact between the rotating spacer and the second end portion of the platform may be a contact making it possible to maintain the platform in position axially and radially.

[0068] Alternatively, the second end portion of each platform may comprise at least one pin projecting substantially axially and shaped to be received in a snug or tight fit in a bore included in a compressor drum. Thus, the platform can be connected directly to the compressor drum. In this case, the installation of a rotating spacer would therefore not be necessary, the platform being directly connected to the compressor drum. The number of parts in the rotor assembly is thus reduced.

[0069] Said at least one pin may comprise an annular notch cooperating with a wall of the compressor drum delimiting said hole. The annular notch forms for example a recessed portion in which the wall of the compressor drum can engage. This makes it possible to maintain the pin in position relative to the compressor drum, which also locks the platform in position relative to the compressor drum. Locking the platform in position relative to the compressor drum also contributes to retaining each blade axially in position, even in the event of a critical event.

[0070] Each hole or notch may be shaped to receive a means for attaching the platform to the fan disc. The attachment means is, for example, a screw or a bolt. Each radial retention hole or radial retention notch thus makes it possible to block the axial and radial movements of the first end portion of the platform, which allows the platform to withstand significant forces without deforming and while remaining integral with the fan disc which carries it.

[0071] Advantageously, the connecting member of the fan disk to the inlet cone is also used as a means of fixing the platform to the fan disk. This reduces the number of parts to be used in the rotor assembly. The hole and / or the notch of each platform is therefore arranged so as to be opposite the cavity formed by the fixing hole and the complementary fixing hole. In addition, this fixing of the platform can contribute to retaining each blade in the fan disk in the event of a critical event. In particular, the connecting member connecting the platform to the fan disk and to the inlet cone can be configured to work in shear in the event of a critical event. The forces due to this shear can be taken up by the two adjacent connecting members, as well as by the rest of the connecting members of the rotor assembly.The forces exerted on the blade in the event of a critical event are thus distributed in the inlet cone, which limits the risk of loss or breakage of the blades.

[0072] The compressor is for example a low pressure compressor.

[0073] The bore included in the compressor drum is for example a through hole. Alternatively, the bore may be a blind hole.

[0074] According to one aspect, a shim is installed in each cell so as to fill a radial clearance formed between a radially internal end of the blade root and a bottom wall of the cell.

[0075] The shim therefore makes it possible to avoid uncontrolled movements of the blade in the radial direction. The shim may in particular be shaped to control the movements of the blade root during a critical event mentioned above. In such circumstances, the blade concerned pivots under the impact, the blade root consequently pivoting in the cell of the disk. The blade, in addition to the rotational movement, can undergo a forward and then backward diving movement, in reaction. The blade can undergo torsional and axial diving movements of different amplitudes. Thanks to the shim, the impact between the blade and the cell in these situations is limited, an energy of this impact being absorbed by the shim. The risks of damage to the blade are thus reduced.

[0076] The shim may be made, at least partially, of an elastically deformable material. For example, the shim may comprise metal portions and semi-rigid elastomer portions. According to one example, the shim may be made of the same material as the blade.

[0077] The wedge may have a parallelepiped shape. In some cases, the wedge has a shape and dimension similar or identical to the bottom wall of the respective cell. In other cases, the wedge has a dimension smaller than the bottom wall of the respective cell.

[0078] A radial dimension of said projecting portion of said hook may be less than a radial dimension of said radial clearance. Also, when the radial clearance is formed, the projecting portion of the axial stop hook is fully engaged in the second portion of the housing. The retention of the blade in the rotor assembly is thus improved.

[0079] A radial dimension of said projecting portion of said hook may be less than a radial dimension of said shim. Also, when the shim fills the radial clearance between the blade root and the bottom wall of the cell, it is ensured that the projecting portion of the axial stop hook is fully engaged in the second portion of the housing. The retention of the blade in the rotor assembly is thus improved.

[0080] According to another aspect, a turbomachine such as a turbojet or a turboprop is provided, comprising a rotor assembly as described above. The turbomachine thus has all the advantages of the rotor assembly presented above. Brief description of the drawings

[0081] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig.l

[0082] [Fig.l] shows a schematic view in longitudinal section of a fan rotor assembly for a turbomachine according to a first embodiment. Fig. 2

[0083] [Fig.2] shows a partial perspective view of a fan disc of the rotor assembly of [Fig.l]. Fig. 3

[0084] [Fig.3] shows a partial perspective view of a detail of the fan disc of [Fig.2] in which blade roots, shown partially in dotted lines, are installed. Fig. 4

[0085] [Fig.4] shows a partial perspective view of an example of a blade for the assembly rotor of [Fig.l]. Fig. 5

[0086] [Fig.5] shows a schematic top view of a portion of the rotor assembly of [Fig.l] comprising an inlet cone, a fan disc and a blade installed in the fan disc. Fig. 6

[0087] [Fig.6] shows a schematic top view of a first example arrangement of a plurality of blades and a plurality of blade platforms for the rotor assembly of [Fig.l]. Fig. 7

[0088] [Fig.7] shows a schematic top view of a second example arrangement of a plurality of blades and a plurality of blade platforms for the rotor assembly of [Fig.l]. Fig. 8

[0089] [Fig.8] shows a schematic view in longitudinal section of a fan rotor assembly for a turbomachine according to a second embodiment. Fig. 9

[0090] [Fig.9] shows a schematic perspective view of an upper face of a platform for the rotor assembly of [Fig.l] or [Fig.8]. Fig. 10

[0091] [Fig. 10] shows a schematic longitudinal sectional view of a fan rotor assembly for a turbomachine according to a second embodiment. Description of the embodiments

[0092] Reference is now made to [Fig.l] partially showing a rotor assembly 10 of a fan for a turbomachine according to a first embodiment. As illustrated, the rotor assembly 10 extends along a longitudinal axis A.

[0093] The rotor assembly 10 may comprise a fan disc 12 and an inlet cone 14.

[0094] The fan disk 12 has a substantially annular shape comprising a radially inner surface 16 and a radially outer surface 18. As seen in [Fig. 2], the radially inner surface 16 and the radially outer surface 18 are connected to each other. For example, a substantially annular intermediate wall 20 connects the radially outer 16 and inner 18 surfaces. In a longitudinal section of the rotor assembly 10, the intermediate wall 20 forms a tab 22 extending for example substantially radially, as shown in [Fig. 1].

[0095] The radially inner surface 16 of the fan disc 12 delimits a cavity 24 shaped to receive a compressor shaft, for example a low-pressure compressor, not shown in the figures. The compressor shaft is configured to rotate about the longitudinal axis A. The fan disc 12 and the compressor shaft are connected to each other in rotation. Thus, the rotation of the compressor shaft makes it possible to drive the fan disc 12 integrally in rotation about the longitudinal axis A. All the other parts forming the rotor assembly 10 which are directly or indirectly connected to the fan disc 12 can also be driven in rotation about the longitudinal axis A integrally with the compressor shaft.

[0096] The fan disk comprises a substantially annular first upstream end portion 25. As will be detailed, the first upstream end portion 25 is shaped to tightly receive a first end portion 27 of the inlet cone 14. In the following, the first upstream end portion 25 of the fan disk 12 will be called the “complementary first end portion”, while the first end portion 27 of the cone 14 will be called the “first end portion”.

[0097] Advantageously, at least one hole 23 passes radially through the first complementary end portion 25 of the fan disc 12. In the following, the hole 23 will also be called a “complementary fixing hole”.

[0098] The radially outer surface 18 comprises a plurality of cells 26. Each cell 26 comprises a groove formed recessed on the radially outer surface 18 of the fan disc 12. The groove formed by each cell 26 may be rectilinear and may extend substantially axially along the entire length of the fan disc 12.

[0099] The cells 26 can be distributed regularly around the longitudinal axis A. Thus, each cell 26 can define with the neighboring cell 26 a tooth 28 which also extends substantially axially along the entire length of the fan disc. Furthermore, each cell 26 can thus be delimited between two successive teeth 28.

[0100] Each cell 26 comprises a first side wall 30, a second side wall 32 and a bottom wall 34. The first and second side walls 30, 32 cor correspond to the lateral wall of the two successive teeth 28 between which the alveolus 26 is formed.

[0101] The bottom wall 34 of each cell 26 is for example included in a plane substantially perpendicular to the radial direction. The first and second side walls 30, 32 are transverse to the bottom wall 34. In particular, the first and second side walls 30, 32 may be inclined relative to the radial direction. Alternatively, the first and second side walls 30, 32 may be parallel to the radial direction.

[0102] As can be seen from Figures 2 and 3, a housing 36 is formed in each of the side walls 30, 32 of the respective cell 26. The housing 36 forms in particular a groove which is open, preferably over its entire extension, in the cell 26. According to a non-limiting example, each housing 36 comprises a first part 36-1 substantially parallel to the axial direction and a second part 36-2 substantially transverse to the first part 36-1. As seen in Figures 2 and 3, the first portion 36-1 extends from an upstream end 37 of the fan disc 12. More specifically, the upstream end 37 is an upstream end of each tooth 28 of the disc 12. The housing 36 is therefore open at the upstream end 37 of the fan disc 12. In the figures, the second portion 36-2 extends from a downstream end of the first portion 36-1, without this being limiting. Also, in the figures, each housing 36 has an L shape.

[0103] Advantageously, the complementary fixing hole 23 is formed through one of the teeth 28. Preferably, a complementary fixing hole 23 is formed through each tooth 28. Thus, the fan disc 12 comprises an annular row of complementary fixing holes 23.

[0104] A downstream end portion of the fan disc 12 may comprise a plurality of portions 38 projecting radially from the radially outer surface 18 of the fan disc 12. Each portion 38 comprises a hole 39 for attaching the fan disc 12 to a compressor 40. The compressor 40 is for example a low-pressure compressor.

[0105] The hole 39 is in particular arranged axially opposite another hole (not shown) arranged in the compressor 40. Thus, a fixing means, preferably removable, such as a screw, can be installed in the hole 39 and the hole of the compressor 40 to fix the fan disc 12 to the compressor 40.

[0106] The inlet cone 14 comprises a first end portion 27 and a second end portion 29. The first end portion 27 is placed downstream of the second end portion 29.

[0107] The first end portion 27 advantageously has a substantially annular shape comprising a radially internal surface 42 and a radially external 44. The radially external surface 44 of the first end portion 27 has a shape and dimension substantially equal to the first complementary end portion 25 of the fan disc 12. Thus, the first end portion 27 of the cone 14 can be tightly mounted in the first complementary end portion 25. As indicated previously, this tight mounting can be obtained by shrink fitting.

[0108] As already explained, the fact of tightly mounting the first end portion 27 of the inlet cone 14 in the fan disc 12 makes it possible to maintain the inlet cone 14 in position radially and axially in the fan disc 12 from a simpler, less expensive assembly using a smaller number of parts. The manufacture of the rotor assembly 10 is therefore simplified.

[0109] Furthermore, as also indicated above, this tight mounting makes it possible to eliminate aerodynamic steps in the rotor assembly 10, which makes it possible to reduce pressure losses. In addition, the tight mounting guarantees the centering of the inlet cone 14 in the fan disc 12, which also reduces the aerodynamic steps.

[0110] At least one fixing hole 45 passes substantially axially through the first end portion 27 of the cone 14. Preferably, the fixing hole 45 passes through the cone 14 from its radially external surface 44 to its radially internal surface 42. Advantageously, when the first end portion 27 of the cone 14 is tightly mounted in the fan disc 12, the fixing hole 45 is radially opposite the complementary fixing hole 23. Thus, the fixing hole 45 and the complementary fixing hole 23 form a radial cavity shaped to receive a connecting member 48. The connecting member 48 makes it possible to connect the fan disc 12 and the inlet cone 14 so as to improve the retention in the axial position of the cone 14 relative to the disc 12. The connecting member 48 is preferably a removable connecting member, for example a screw or a bolt.

[0111] As indicated previously, the fan disc 12 may comprise an annular row of complementary fixing holes 23. In this case, the first end portion 27 is preferably traversed radially by a plurality of fixing holes 45 forming an annular row of fixing holes 45. Advantageously, the plurality of fixing holes 45 are arranged in the annular row so that, when the first end portion 27 of the cone 14 is mounted tightly in the fan disc 12, each fixing hole 45 is radially opposite one of the complementary fixing holes 23.

[0112] In some cases, a nut 49 may be crimped into each fixing hole 45. The nut 49 may be an independent part connected to a wall of each fixing hole 49. The nut 49 may alternatively be made integral with the wall of the respective fixing hole 49.

[0113] The nut 49 makes it possible to hold the connecting member 48 in position inside the fixing hole 45 and the complementary fixing hole 23.

[0114] The second end portion 29, the longitudinal section of which is only partially illustrated in [Fig. 1], advantageously has a substantially conical shape, flared from upstream to downstream.

[0115] The downstream end of the second end portion 29 of the inlet cone 14 preferably has a cross-section greater than the cross-section of the first end portion 27 of the cone 14. An annular wall 46 extending substantially radially connects the upstream end of the first end portion 27 of the inlet cone 14 to the downstream part of its second end portion 29. As can be seen from [Fig. 1], the annular wall 46 of the inlet cone 14 makes it possible to close an upstream end of each cell 26.

[0116] The rotor assembly 10 further comprises at least one blade 50. Preferably, the rotor assembly 10 comprises the same number of blades 50 as cells 26 included in the fan disk 12. As will be detailed, each blade 50 is partially installed in a respective cell 26.

[0117] [Fig.4] shows an example of a blade 50. Each blade 50 may be made of a metallic or composite material, for example a 3D woven composite.

[0118] The blade 50 comprises a blade root 52, a stilt 54 and a blade 56. The blade 50 further comprises a first face 58, called the intrados, and a second face 60, called the extrados. The intrados 58 and the extrados 60 are substantially parallel to a plane comprising the axial and radial directions when the blade 50 is installed in the corresponding cell 26.

[0119] The blade root 52 of each blade 50 is shaped to be installed in the corresponding cell 26. For this purpose, each blade root 52 may have a shape adapted to be installed in the respective cell 26. According to a non-limiting example, each blade root 52 may have a shape complementary to the shape of the cell 26 in which the blade 50 is installed.

[0120] In [Fig.4], the blade root 52 comprises a body 62 extending along an axis B. When the blade root 52 is installed in the respective cell 26, the axis B is substantially parallel to the longitudinal axis A of the rotor assembly 10. The body 62 has a section along a plane perpendicular to the axis B which is substantially frustoconical.

[0121] The blade root 52 further comprises an axial stop hook 64. The hook 64 is for example arranged on an upstream end portion of the body 62 of the blade root 52. More precisely, when the blade root 52 is installed in the respective cell 26, the hook 64 projects radially from the body 62. In other words, the hook 64 is included in a plane substantially perpendicular to the axis B.

[0122] The hook 64 comprises a projecting portion 66. In this case, the projecting portion 66 comprises a first protrusion 68 and a second protrusion 69. The first and second protrusions 68, 69 protrude from opposite sides of the hook 64. When the blade 50 is installed in the respective cell 26, the first and second protrusions 68, 69 protrude in a direction substantially perpendicular to the plane comprising the substantially axial and radial directions.

[0123] The first protrusion 68 is shaped to be engaged in the housing 36 of the first side wall 30 of the respective cell 26. The second protrusion 69 is shaped to be engaged in the housing 36 of the second side wall 32 of the respective cell 26. In particular, the first protrusion 68 and the second protrusion 69 have a shape allowing them to be inserted into the first part 36-1 and the second part 36-2 of the respective housing 36. Advantageously, when the first protrusion 68 or the second protrusion 69 are engaged in the first part 36-1, a clearance exists between the first protrusion 68 and the corresponding first part 36-1, and between the second protrusion 69 and the corresponding first part 36-1. Thus, the hook 64 can be moved axially in the housing 36, in particular in its first part 36-1.Preferably, in the second portion 36-2 of the respective housing 36, the first protrusion 68 and the second protrusion 69 are mounted axially adjusted. In other words, the axial dimension of the first and second protrusions 68, 69 is substantially equal to the axial dimension of the second portion 36-2 of the respective housing 36. The axial movement of the hook 64 in the housing 36 is then blocked, as will be detailed.

[0124] The stilt 54 is arranged between the blade root 52 and the blade 56, in particular in the radial direction when the blade 50 is installed in the corresponding cell 26. The stilt 54 provides the mechanical connection between the blade 56 and the blade root 52. The stilt 54 may, for example, have a rectilinear or curvilinear shape.

[0125] The blade 56 extends from the stilt 54, substantially radially when the vane 50 is installed in the corresponding cell 26. The blade 56 may have a curvilinear shape.

[0126] According to a non-limiting example, when mounting the blade 50 in the respective cell 26, the blade 50 is oriented from its root 52 to its blade 56 in the direction of the force of gravity. That is to say, when installing the blade 50 in the cell 26, the blade root 52 is in a higher position relative to the ground than the blade 56.

[0127] The blade root 52 is gradually introduced into the cell 52 from an axial movement of the blade 50. The blade root 52 can be dimensioned so that during the axial movement of the blade 50 in the cell 26, a radially internal end 52-1 of the blade root 52 is radially in contact with the bottom wall 34 of the cell 26.

[0128] As previously indicated, the first part 36-1 of each housing is open at the upstream end 37 of the fan disc 12. The blade root 52 is therefore also dimensioned so as to ensure that during axial movement of the blade 50 in the cell 26, the projecting portion 66 is engaged in each housing 36 of the cell 26. In particular, during axial movement of the blade 50 in the cell 26, the protrusion 68 and the protrusion 69 each engage the first portion 36-1 of the respective housing 36 of the cell 26 in which each of them is received. As indicated previously, a clearance exists between each protrusion 68, 69 and the first portion 36-1 of the respective housing 36. This clearance allows the axial sliding of each protrusion 68, 69 in the first portion 36-1 of the respective housing 36.

[0129] Once each protrusion 68, 69 of the projecting portion 66 of the hook 64 is radially opposite the second portion 36-2 of the respective housing 36, the force of gravity causes the radial displacement of the blade root 52 in the corresponding cell 26. Each protrusion 68, 69 is then engaged in the second portion 36-2 of the corresponding housing 36.

[0130] As indicated, each protrusion 68, 69 is mounted axially adjusted in the second part 36-2 of the corresponding housing 36. Axial displacements of the blade root 52 are thus avoided. The blade root 52 is thus retained, even in the event of critical events such as those indicated previously, in the rotor assembly 10 from a retention system directly integrated in the blade 50, without the need to use additional parts, such as locks, which reduces the number of parts to be machined and assembled.

[0131] Of course, according to an alternative embodiment, the projecting part 66 of the hook could comprise only one of the protrusions 68, 69. The installation of the blade 50 in the respective cell 26 could then be done in the manner explained above but with only one protrusion 68, 69 which is engaged in a housing 36.

[0132] The radial displacement of the blade root 52 leading to the introduction of the projecting part 66 into the second part 36-2 of each housing 36 causes the radially internal end 52-1 of the blade root 52 to move away from the bottom wall 34 of the cell 26. A radial clearance 67 is therefore formed between the radially internal end 52-1 of the root 52 and the bottom wall 34 of the cell 26. Advantageously, a radial dimension RI of the projecting part 66 of the hook 54 is less than a radial dimension R2 of the radial clearance 67. Also, when the radial clearance 67 is formed, the projecting part 66 of the hook 64 is fully engaged in the second part 36-2 of the corresponding housing 36. The retention of the blade 50 in the rotor assembly 10 is thus improved.

[0133] As visible in [Fig.l], a shim 70 is arranged radially between the radially internal end 52-1 of the foot 52 and the bottom wall 34 of the cell 26.

[0134] The shim 70 may be made, at least partially, of an elastically deformable material. formable. For example, the shim 70 may include metal portions and semi-rigid elastomer portions. In one example, the shim 70 may be made of the same material as the blade 50.

[0135] The longitudinal dimension of the wedge 70 is for example substantially equal to the longitudinal dimension of the cell 26 in which it is installed.

[0136] The radial dimension of the shim 70 is chosen so as to be able to fill the radial clearance 67. Advantageously, the shim 70 completely fills the radial clearance 67. The shim 70 therefore makes it possible to avoid uncontrolled movements of the blade 50 in the radial direction. Furthermore, in the event of a critical event suffered by the blade 50, the impact between the blade 50 and the cell 26 is limited, an energy of this impact being absorbed by the shim 70. The risks of damage to the blade 50 are thus reduced.

[0137] Preferably, the radial dimension RI of the projecting portion 66 of the hook 64 is less than the radial dimension of the shim 70. Also, when the shim 70 fills the radial clearance 67, it is guaranteed that the projecting portion 66 of the hook 64 is fully engaged in the second portion 36-2 of the corresponding housing 36. The retention of the blade 50 in the rotor assembly 10 is thus improved. The radial dimension of the shim 70 is for example equal to the radial dimension R2 of the radial clearance 67.

[0138] The rotor assembly 10 further comprises at least one blade platform 72. The rotor assembly 10 comprises, for example, the same number of platforms 72 as blades 50. The platforms are arranged adjacent to each other around the longitudinal axis A. In some cases, each platform 72 is an added part. In other cases, each platform 72 is formed in one piece with a respective blade 50. Each platform 72 may be made of the same material as the blades 50, or of a different material.

[0139] Now one of the platforms 72 will be described. Preferably, all of the platforms 72 of the rotor assembly 10 are similar or identical to that described below.

[0140] The platform 72 comprises an upper face 72-1 and a lower face 72-2. The platform 72 further comprises a first end portion 74 and a second end portion 76. The first end portion 74 comprises an upstream edge 75 of the platform 72, and the second end portion 76 comprises a downstream edge 77 of the platform 72. The upstream 75 and downstream 77 edges are connected to each other by a first lateral edge 79 and a second lateral edge 80. The first lateral edge 79 and the second lateral edge 80 of the platform 72 are preferably substantially parallel to each other.

[0141] The first end portion 74 of the platform 72 extends substantially axially. Also, the first end portion 74 can come into radial support with at least one of the teeth 28 of the fan disc 12.

[0142] As illustrated in [Fig.6], each platform 72 may comprise a radial fixing notch 82 in its first end portion 74. Preferably, each platform 72 comprises two notches 82. In particular, a first notch 82 is arranged on the first lateral edge 79 and a second notch 82 is arranged on the second lateral edge 80 of the platform 72. Each notch 82 passes entirely through the platform 72 between its upper face 72-1 and its lower face 72-2.

[0143] Advantageously, as visible in [Fig. 6], when two platforms are arranged adjacently on the fan disc 12, the first notch 82 of one of the platforms 72 and the second notch 82 of the other platform 72 are radially opposite the cavity formed by the fixing hole 45 and the complementary fixing hole 23. The notches 82 of the two neighboring platforms 72 thus form an orifice shaped to receive the connecting member 48. Also, two adjacent platforms 72 can be connected to the fan disc 12 from the connecting member 48 used to connect the fan disc 12 and the inlet cone 14.

[0144] Alternatively, as visible in [Fig.7], the first end portion 74 of each platform 72 may have a radial fixing hole 84 passing entirely through the platform 72 between its upper face 72-1 and its lower face 72-2. The hole 84 is for example substantially circular. The hole 84 is in particular placed in the platform 72 so as to be radially opposite the cavity formed by the fixing hole 45 and the complementary fixing hole 23 when the platform 72 comes to bear against the fan disc 12. Also, the platform 72 may be connected to the fan disc 12 from the connecting member 48 used to connect the fan disc 12 and the inlet cone 14.

[0145] The connecting member 48 of the fan disk 12 to the inlet cone 14 is also used as a means of fixing the platform 72 to the fan disk 12, the number of parts in the assembly 10 is reduced. In addition, this fixing of the platform 72 can contribute to retaining each blade 50, in particular each blade root 52, in the fan disk 12 in the event of a critical event. In particular, the connecting member 48 is configured to work in shear in the event of a critical event. The forces due to this shear can be taken up by the two adjacent connecting members 48, as well as by the rest of the connecting members 48. The forces exerted on the blade 50 in the event of a critical event are thus distributed in the inlet cone 14, which limits the risk of loss or breakage of the blades 50.

[0146] The second end portion 76 is inclined relative to the axial direction so as to gradually move away in the radial direction from the fan disc 12. The second end portion 76 is shaped to cooperate with a rotating spacer 86 of the assembly 10. As visible in [Fig.l], the rotating spacer 86 is connected on the one hand to a rectifier 88 (or “Inlet Guide Vane”, IGV, according to the term Anglo-Saxon minology), and on the other hand to a drum 90 of the compressor 40. To connect the rotating spacer 86 to the drum 90, the drum 90 comprises a portion 92 projecting substantially radially from the drum 90. The portion 92 is axially traversed by a bore (not illustrated in [Fig.l]) which is axially opposite another bore (not illustrated in [Fig.l]) included in the rotating spacer 86. A connecting member, for example a screw, can then be introduced into the bores of the rotating spacer 86 and of the drum 90 to fix the rotating spacer 86 to the drum 90.

[0147] The second end portion 76 of the platform 72 comprises a shoulder 94 in the upper surface 72-1 of the platform 72. Downstream of the shoulder 94, the platform 72 is in contact with a radially internal surface of the rotating spacer 86. This makes it possible to hold the platform 72 radially in position. The shoulder 94 comes into contact with the upstream end of the rotating spacer 86. This, together with the fixing of the first end portion 74 on the disc 12 from the connecting member 48, makes it possible to hold the platform 72 axially in position.

[0148] Thus, the retention of the platform 72 in the assembly 10 is guaranteed, which also improves the retention of the blade 50 in the assembly 10.

[0149] According to an alternative embodiment illustrated by [Fig. 8], the second end portion 76 of the platform 72 may be shaped to cooperate directly with the rectifier 88 and the compressor drum 90. For this purpose, the second end portion 76 of the platform comprises at least one pin 98 shaped to be introduced and retained axially and radially in the bore of the portion 92 of the drum 90. In [Fig. 8], the bore of the portion 92 is referenced 96. In particular, the part of the pin 98 which is received in the bore 96 preferably has dimensions allowing adjusted or tight mounting of the pin in the bore 96.

[0150] As can be seen from Figures 8 and 10, the pin 98 may have an L-shape, without this being limiting. In certain cases, the part of the pin 98 which is received in the bore 96 comprises an annular notch 100. The wall of the portion 92 of the compressor drum can thus engage radially in the notch 100. This makes it possible to improve the holding in position of the pin 96 relative to the compressor drum 90, which also locks the platform 72 in position relative to the compressor drum 90. The locking in position of the platform 72 relative to the compressor drum 90 also contributes to axially retaining each blade 50 in position, even in the event of a critical event.

[0151] In the example of [Fig.8], the second end portion of the platform 76 also includes the shoulder 94 described above. However, in the example of [Fig.8], the shoulder 94 cooperates axially with an upstream end of the rectifier 88. This, together with the fixing of the first end portion 74 on the disc 12 from of the connecting member 48 makes it possible to maintain the platform 72 axially in position.

[0152] Downstream of the shoulder 94, the platform 72 is radially opposite a radially internal surface of the rectifier 88. This makes it possible to contribute to the radial retention of the platform 72 in position. The shoulder 94 comes into contact with the upstream end of the rotating spacer 86.

[0153] The configuration of [Fig.8] makes it possible to remove the rotating spacer 86 from the assembly 10. This simplifies the assembly and machining of the assembly 10. Furthermore, the weight of the assembly 10 can thus be reduced.

[0154] Figures 6 and 7 show two different arrangements of the blades 50 and the platforms 72.

[0155] In a first arrangement, illustrated in [Fig. 6], each platform 72 is arranged around the intrados 56 and the extrados 58 of one of the blades 50. For this purpose, each platform 72 comprises a groove 102, visible in FIGS. 9 and 10. The groove 102 is capable of introducing each blade 50 into the respective platform 72. Alternatively, in this configuration the platform 72 can be made in one piece with the corresponding blade 50. Such a configuration is called here a “sock configuration”.

[0156] As can be seen from [Fig.6], in the sock configuration, the gap between two neighboring blades 50 is occupied by half of two neighboring platforms.

[0157] In the arrangement illustrated by [Fig.7], each platform 72 can be mounted in the interval between two neighboring blades 50. In this case, a first platform is adjacent to the intrados 56 of the blade 50, and a second platform distinct from the first is adjacent to the extrados 58 of the blade 50.

[0158] The present disclosure is not limited to the embodiments described above, only as an example, but it encompasses all the variants that a person skilled in the art may envisage within the framework of the protection sought.

Claims

1.

2.

3.

4. Claims A fan rotor assembly (10) for a turbomachine, the rotor assembly (10) comprising an inlet cone (14) and a fan disc (12) arranged around a longitudinal axis (A) of the rotor assembly (10), wherein the inlet cone (14) comprises a first end portion (27) and the fan disc (12) comprises a first complementary end portion (25), the first end portion (27) and the first complementary end portion (25) being substantially annular, wherein said first end portion (27) and the first complementary end portion (25) are mounted tightly together, wherein said first end portion (27) of the inlet cone (14) comprises at least one fixing hole (45), said first complementary end portion (25) of the fan disc (12) comprising at least one complementary fixing hole (23),the at least one fixing hole (45) being arranged radially opposite the at least one complementary fixing hole (23), a connecting member (48) of the fan disc (12) to the inlet cone (14) being installed in the at least one fixing hole (45) and the at least one complementary fixing hole (23), the connecting member (48) extending substantially radially in a radial cavity formed by the at least one fixing hole (45) and the at least one complementary fixing hole (23), said assembly further comprising at least one blade platform (72), the at least one platform (72) comprising at least one radial retention hole (84) or at least one radial retention notch (82), said hole (84) or notch (84) being arranged radially opposite said complementary fixing hole (23), said connecting member (48) radially passing through said hole (84) or notch (82)., A rotor assembly (10) according to claim 1, wherein said first end portion (27) is clamped in said complementary end portion (27). Rotor assembly (10) according to the preceding claim, wherein a nut (49) is crimped in said at least one fixing hole (45) and / or in said at least one complementary fixing hole (23). Rotor assembly (10) according to claim 1 or 3, wherein said first end portion (27) comprises an annular row of fixing holes (45) distributed around the longitudinal axis (A) of the rotor assembly (10), the first complementary end portion (25) comprising an annular row of complementary fixing holes (23) distributed around the longitudinal axis (A) of the rotor assembly (10), each fixing hole (45) being radially opposite a respective complementary fixing hole (23).

5. Rotor assembly (10) according to one of the preceding claims, wherein a radially external surface (18) of the fan disc (12) comprises a plurality of cells (26) distributed around the longitudinal axis (A) of the rotor assembly (10), the rotor assembly (10) further comprising a plurality of blades (50), each blade (50) comprising a blade root (52) engaged in one of said cells (26), the blade root (50) comprising an axial stop hook (64) comprising a projecting portion (66) mounted axially adjusted in a housing (36) of the fan disc (12).

6. Rotor assembly (10) according to the preceding claim and one of claims 1, 3 and 4, wherein the radially external surface (18) of the fan disc (12) comprises a plurality of teeth (28), each tooth (28) being arranged between two successive cells (26), the at least one complementary fixing hole (23) extending substantially radially through a respective tooth (28) of the fan disc (12).

7. Rotor assembly (10) according to one of claims 1, 5 and 6, in which a shim (70) is installed in each cell (26) so as to fill a radial clearance (67) formed between a radially internal end (52-1) of the blade root (52) and a bottom wall (34) of the cell (26).

8. A turbomachine such as a turbojet or a turboprop, comprising a rotor assembly (10) according to any one of claims 1 to 7.

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