TURBOMACHINE FAN ROTOR

Abstract

The invention relates to a fan rotor for a turbomachine, comprising including a fan disk, fan blades with a leading edge and a trailing edge, platforms inserted between the blades and fixed to the periphery of the disk, each including an aerodynamic surface extending from the leading edges to the trailing edges of the blades. The aerodynamic surface includes an upstream longitudinal portion on the side of the leading edges and a downstream longitudinal portion on the side of the trailing edges, the upstream longitudinal portion being supported by a first member of the platform fixed to the disk in a pivotable manner, and the downstream longitudinal portion being independent of the upstream longitudinal portion and supported by a second member of the platform which is independent of the first member and fixed to the disk in a pivotable manner.

Claims

1. A fan rotor for a turbomachine, this rotor having an axis of rotation and comprising: a fan disc, fan blades comprising roots press-fitted in sockets in the periphery of said disc, each blade comprising an intrados, an extrados, a leading edge and a trailing edge, platforms interposed between the fan blades and fixed to the periphery of the disc, each platform comprising an aerodynamic surface extending along said axis substantially from the leading edges to the trailing edges of the blades between which this platform is mounted, wherein said aerodynamic surface comprises an upstream longitudinal portion located on the side of the leading edges of the blades and a downstream longitudinal portion, independent of the upstream longitudinal portion, located on the side of the trailing edges of the blades, the upstream longitudinal portion being supported by a first member of the platform which is fixed to said disc and the downstream longitudinal portion being supported by a second member of the platform which is independent of said first member and which is fixed to said disc.

2. The rotor according to claim 1, wherein the second member is fixed to the disc in a pivotable manner.

3. The rotor according to claim 1, wherein an axial dimension of the upstream longitudinal portion, along an axis of rotation of the rotor, is between 0.5 times and 1.5 times an axial dimension of the downstream longitudinal portion.

4. The rotor according to claim 1, wherein the second member is fixed to the disc by a single fixing element defining a pivot axis of this downstream longitudinal portion with respect to the disc.

5. The rotor according to claim 4, wherein the second member comprises a fixing bracket axially applied to a flange of the disc, the fixing bracket comprising an axial orifice aligned with an axial orifice of the flange, said fixing element passing through the axial orifices of the fixing bracket and of the flange.

6. The rotor according to claim 5, in which the orifice of the fixing bracket at least partially receives a ring through which said fixing element passes, this ring being clamped and separated by axial (Ja) and radial (Jr) clearances from said fixing bracket.

7. The rotor according to claim 6, wherein the fixing element is a screw, a head of which rests on a face of the flange or of an insert on this face, and a threaded rod receives a nut which rests on said ring.

8. The rotor according to claim 1, wherein one of the longitudinal portions comprises, at its longitudinal end located on the side of the other of the longitudinal portions, a bearing surface for the other longitudinal portion.

9. The rotor according to claim 8, wherein the longitudinal portions comprise circumferential edges facing each other, said bearing surface extending along one of these edges over only one part of the circumferential extent of this edge.

10. An aircraft turbomachine, comprising a rotor according to claim 1.

Description

BRIEF DESCRIPTION OF FIGURES

[0036] Other characteristics, purposes and advantages of the present invention will become apparent from the following detailed description and from the attached drawings, which are given as non-limiting examples and in which:

[0037] FIG. 1 is a schematic representation of a partial cross-sectional view of a fan rotor according to the prior art,

[0038] FIG. 2 is a schematic representation of a partial perspective view of a fan rotor according to an embodiment in accordance with the present invention, this figure showing portions of a blade and a disc of fan and a platform with an aerodynamic surface comprising upstream and downstream longitudinal portions and their fixing members to a tooth of the fan disc, the longitudinal portions being shown in the mounted position in this FIG. 2,

[0039] FIG. 3 is a schematic representation of a perspective view of the fan rotor shown in FIG. 2, with only the upstream longitudinal portion of the aerodynamic surface shown in this FIG. 3,

[0040] FIG. 4 is a schematic representation of a perspective view of the fan rotor shown in FIG. 2, with only the downstream longitudinal portion of the aerodynamic surface shown in this FIG. 4,

[0041] FIG. 5 is a schematic representation of a perspective view of a platform forming part of a fan rotor according to the invention previously shown in FIGS. 2 to 4,

[0042] FIG. 6 is a schematic representation of a cross-sectional view of the second member of the downstream longitudinal portion of the aerodynamic surface of the platform forming part of a fan rotor according to an embodiment of the present invention, the second member being connected to a tooth of a fan disc of the rotor by means of a flange.

[0043] It should be kept in mind that the figures are given as examples and are not limiting of the invention. They are schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily on the scale of practical applications. In particular, the dimensions of the various elements illustrated are not representative of reality. For example, in FIGS. 2 to 4, only one fan blade is shown, the other blades having been removed for a better view of the first and second members of the longitudinal portions of the aerodynamic surface.

DETAILED DESCRIPTION OF THE INVENTION

[0044] In the following, reference is made to all figures taken in combination. Where reference is made to a specific figure or figures, these figures are to be taken in combination with the other figures for the recognition of the designated numerical references.

[0045] Referring mainly to FIGS. 2 to 6, the present invention relates to a fan rotor 1 advantageously intended for an aircraft turbomachine.

[0046] Such a rotor 1 is mounted so as to rotate about an axis of rotation and comprises a fan disc 2 and fan blades 3 comprising roots press-fitted in sockets in the periphery of said disc 2, of which only one blade 3 is visible. Each blade 3 comprises an intrados, an extrados, a leading edge 3a and a trailing edge 3b.

[0047] A periphery of the disc 2 is advantageously toothed by being provided with teeth 16, advantageously of trapezoidal section and extending axially on the disc 2 with respect to the axis of rotation of the rotor 1. At least one wedge 17 is provided on the upstream side between two adjacent teeth 16 which form a socket for receiving a root of a blade 3, this wedge 17 being intended to axially block the blade root in its corresponding socket.

[0048] Platforms 4 are interposed between the fan blades 3 and fixed to the periphery of the disc 2. Each platform 4 can therefore be interposed between two consecutive fan blades 3.

[0049] Each platform 4 comprises an aerodynamic surface, referenced 4a in FIG. 2, extending along said axis substantially from the leading edges 3a to the trailing edges 3b of the two blades 3 between which this platform 4 is mounted. According to the present invention, the aerodynamic surface 4a comprises an upstream longitudinal portion 40 located on the side of the leading edges 3a of the blades 3 and a downstream longitudinal portion 41 located on the side of the trailing edges 3b of the blades 3.

[0050] The upstream longitudinal portion 40 of the aerodynamic surface 4a is supported by a first member 5 of the platform 4 which is fixed in a pivotable manner to the fan disc 2. The downstream longitudinal portion 41 of the aerodynamic surface 4a is supported by a second member 6 of the platform 4.

[0051] This second member 6 is independent of the first member 5 and is fixed in a pivotable manner to the fan disc 2.

[0052] The second member 6 allows the downstream longitudinal portion 41 to follow the displacements of the trailing edge 3b of the two associated fan blades 3. In operation, the downstream longitudinal portion 41 of the aerodynamic surface 4a can perform a movement of rotation about its pivotal connection with the fan disc 2.

[0053] The main difficulty in implementing the present invention is to manage a radial clearance between the upstream longitudinal portion 40 and the downstream longitudinal portion 41. This clearance must be neither too small to allow the two portions to rotate between each other, nor too large to ensure that the portions are centered with respect to each other.

[0054] In addition, the rotation of the downstream longitudinal portion 41 with respect to the upstream longitudinal portion 40 results in the creation of a potential step in the duct of the aerodynamic surface 4a.

[0055] Furthermore, it is also important to implement a seal technology capable, on the one hand, of managing the interface between the two longitudinal portions 40, 41 and, on the other hand, a seal capable of compensating the clearance necessary for the rotation of the downstream longitudinal portion 41 and the downstream shell referenced 15 in FIG. 1. The seal can be an O-ring, a split seal or an Omega seal, etc.

[0056] Referring to FIG. 5, the platform 4 may also comprise a housing 18 on one of its longitudinal sides supporting the first and second members 5, 6, the housing 18 may be arranged between the first and second members 5, 6.

[0057] The downstream longitudinal portion 41 may have a free end 41a bent toward the fan disc 2, said free end 41a abutting against a piece not shown in FIGS. 2 to 5 but shown in FIG. 1 as a downstream shell 15 secured by a leg to the fan disc 2.

[0058] The aerodynamic surface 4a may be slightly concave on its side facing the two fan blades 3 framing it and curved in its width.

[0059] Without being limiting, an axial dimension of the upstream longitudinal portion 40 may be between 0.5 times and 1.5 times an axial dimension of the downstream longitudinal portion 41. It follows that the axial dimension of the upstream longitudinal portion 40 may be smaller than, equal to, or larger than the axial dimension of the downstream longitudinal portion 41.

[0060] The first member 5 may be supported by a bent end 40a of the upstream longitudinal portion 40. The bent end 40a of the upstream longitudinal portion 40 may be secured to the fan disc 2 by a securing element, thus forming the first member 5, preferably one of the teeth 16 arranged at the circumference of the fan disc 2. The bent end 40a of the upstream longitudinal portion is preferably secured to a longitudinal end of the tooth 16 by the rim of the tooth 16 forming its thickness.

[0061] The second member 6 may be fixed to the fan disc 2 by a single fixing element 7 defining a pivot axis of this downstream longitudinal portion 41 relative to the disc 2.

[0062] A width of the downstream longitudinal portion 41 may be increased by approaching the free end of the downstream longitudinal portion 41 advantageously supporting the bent edge. This depends on whether the distance between two consecutive fan blades 3 remains constant or not.

[0063] Still referring mainly to FIGS. 2 and 6 and more particularly to FIG. 6, the second member 6 associated with the downstream longitudinal portion 41 may comprise a fixing bracket 6 axially applied to a flange 8 of the fan disc 2.

[0064] The flange 8 may extend from a tooth 16 on the periphery of the fan disc 2, at a longitudinal end of the tooth 16 furthest from the first member 5. The flange 8 may be supported by a face of the tooth 16 opposite an inner face of the aerodynamic surface 4a supporting the first and second members 5, 6, advantageously extending perpendicularly to the face of the tooth 16 supporting it.

[0065] The fixing bracket 6 may be elongated, with the downstream longitudinal portion 41 extending away from the disc 2. The fixing bracket 6 may have a bent end part 6b with an orifice 6a therethrough.

[0066] This orifice 6a of the fixing bracket 6 is an axial orifice aligned with an axial orifice 8a of the flange 8 in the fixing position of the second member 6. The bent end part 6b of the fixing bracket 6 then rests against the flange 8 of the fan disc 2.

[0067] As particularly well visible in FIG. 6, the fixing element 7 passes through the axial orifice 6a of the bent end part 6b of the fixing bracket 6 and the axial orifice 8a of the flange 8.

[0068] In order to allow a freedom of rotation of the bent end part 6b of the fixing bracket 6 of the second member 6 with respect to the fixing element 7, the orifice 6a of the bent end part 6b of the fixing bracket 6 may at least partially receive a ring 9 through which the fixing element 7 passes.

[0069] Thus, there may be an inner portion 9a of the ring 9 housed in the orifice 6a of the bent end part 6b of the fixing bracket 6, the inner portion 9a of the ring 9 being interposed between an inner wall of the orifice 6a and an outer wall of the fixing element 7. The remainder of the ring 9 is an outer portion 9b of the ring 9 disposed outside the bent end part 6b and capable of forming a collar 9b capable of abutting against an axial displacement of the bent end part 6b of the fixing bracket 6.

[0070] The ring 9 can be clamped axially against the flange 8 of the disc 2, thus ensuring a secure fixing, but still separated by axial clearances Ja and radial clearances Jr from the bent end part 6b of the fixing bracket 6. Thus, the bent end part 6b of the fixing bracket 6 can pivot about the fixing element 7 due to the axial clearance Ja and radial clearance Jr with the ring 9.

[0071] The radial clearance Jr may thus be limited by the portion of the ring 9 internal to the bent end part 6b and the axial clearance Ja may be limited by the portion of the ring 9 external to the bent end part 6b, advantageously in the form of a collar 9b abutting against a removal of the flange 8 in the axial direction of the bent end part 6b of the fixing bracket 6.

[0072] Still referring mainly to FIG. 6, the fixing element 7 may be a screw having a head 7a and a threaded rod.

[0073] The head 7a of the screw may be supported on a face of the flange 8 opposite that facing the ring 9 or of an insert 10 on this face, the latter alternative being shown in FIG. 6, the insert 10 being for example a washer, or as here, a piece forming part of a low-pressure compressor drum of the turbomachine. It is also possible to replace the head 7a with a nut.

[0074] At its other free end, the threaded rod can also receive a nut 11 which rests on the ring 9 and clamps it against the flange 8 by means of its inner portion 9a at the bent end part 6b of the fixing bracket 6.

[0075] Referring more particularly to FIG. 3 which shows an upstream longitudinal portion 40 without the presence of a downstream longitudinal portion 41, one 40 of the longitudinal portions 40, 41, in FIG. 3 the upstream longitudinal portion 40 which is not limiting, may comprise, at its longitudinal end located on the side of the other 41 of the longitudinal portions 40, 41, in FIG. 3 the downstream longitudinal portion 41, a bearing surface 12 for this other longitudinal portion 41.

[0076] This allows to avoid a mismatch between upstream and downstream longitudinal portions 40, 41 and to have a support of the downstream longitudinal portion 41 by the upstream longitudinal portion 40 at one end of the downstream longitudinal portion 41 at a distance from the second member 6.

[0077] As particularly well visible in FIGS. 3 and 4 taken in combination, the longitudinal portions 40, 41 of the aerodynamic surface 4a may comprise circumferential edges facing each other. The bearing surface 12 may extend along one of these edges, over only a part of the circumferential extent of that edge.

[0078] This part of the bearing surface 12 may be arranged symmetrically with respect to the circumferential edge bearing it with only end portions of the circumferential edge bearing the bearing surface 12 not being connected to the bearing surface 12. Alternatively, the bearing surface 12 may be supported by a major part of the circumferential edge.

[0079] A particularly advantageous application of such a fan rotor 1 may be for a turbomachine, advantageously an aircraft turbomachine.

[0080] The invention is by no means limited to the described and illustrated embodiments which have been given only as examples.