EP4341533A1

EP4341533A1 - Platform for a fan assembly

Info

Publication number: EP4341533A1
Application number: EP22730582.8A
Authority: EP
Inventors: Jérémy Philippe Pierre EDYNAK; Eddy Keomorakott SOURYAVONGSA
Original assignee: Safran Aircraft Engines SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 2021-05-18
Filing date: 2022-05-13
Publication date: 2024-03-27
Also published as: WO2022243628A1; FR3123088B1; CN117355663A; FR3123088A1; US20240229669A1

Abstract

The present invention relates to a platform (6) for a fan assembly (1), comprising a flow passage wall (8) extending in an axial direction having an upstream end and a downstream end, and comprising two axial stiffeners (10). The platform (6) comprises radial retention means (16, 18, 20, 22) positioned at the upstream end and at the downstream end of the flow passage wall (8), the radial retention means (16, 18, 20, 22) being designed to each define a sliding connection with a corresponding shroud of the fan assembly (1) and in that it comprises tangential retention means designed to define a sliding pivot connection between the platform (6) and a disc (2) of the fan assembly (1).

Description

BLADE WHEEL PLATFORM

FIELD OF THE INVENTION

The present invention relates to the field of bladed wheel platforms.

STATE OF THE ART

In a known way, as shown schematically in Figure 1, a low pressure compressor can be composed of a bladed fan wheel X which comprises a casing, a fan disc I, several blades and their retention systems, several platforms III , and an upstream shell IV.

In a known way, the platform is an integral part of the bladed wheel of the fan constituting the first mobile wheel stage. It must perform the following functions:

• Main aerodynamic function:

- Define an air flow path.

• Satisfy all operating conditions:

- Ensure performance for the entire flight envelope

- Ensure security requirements

- Ensure engine availability for commercial use

• Integration in the engine environment:

- Have consistent interfaces at the borders of the moving wheel stage,

- Avoid disturbances at the level of the other stages of the low pressure compressor.

More specifically, the performance and integration requirements translate into good control of the airtightness of the blade near its root retained in the disc. This tightness is directly controlled by the capacity of the platform to be associated with the blade near its foot, and this at any point of operation. Up to a certain clearance, it is possible to fill with the use of a gasket. From a certain clearance, it is difficult to ensure a seal.

In addition, the performance and integration requirements also translate into an ability to decrease the hub ratio. The lower this ratio, the more the flow increases and the more efficient the blower will be. The reduction of this hub ratio prevents the integration of a so-called “box” platform known from the prior art. Indeed these platforms have a box which brings the necessary stiffness to the platform to withstand acceptable levels of displacement and mechanical stress. The platform is retained upstream and downstream, for example in correspondence of shells and for example an upstream end of the platform may comprise a substantially radial leg which is fixed by bolts (on the principle, refer for example to the teaching of the document FR-2 992 676) on the disc or an intermediate part connected to the disc. Document FR-3 029 563 proposes a key for locking the box relative to the disk. This method of attachment is very stable but makes the platform particularly bulky, resulting in a high hub ratio.

Thus, many documents of the prior art seek to solve the problem of the antagonism between an optimal fixation of the platform and the obtaining of a low hub ratio. One can for example cite the document US 20140186187 which describes a platform having a refined upstream attachment, so as to maintain a low hub ratio.

However, currently, there are two main solutions for attaching a platform to the disc while maintaining a low hub ratio. According to a first solution, the platform is screwed onto radial extensions of the disc (as is the case for the platform described in document US 20140186187). According to another arrangement, the platform is retained by a plurality of hooks carried by the disc.

These known solutions are particularly restrictive. Indeed, the multiplicity of screws or hooks imposes a specific assembly kinematics often involving tilting of the platform around the axis of rotation, then an axial movement to engage the platform in the hooks. However, this axial movement can have an impact on the clearance presented above, by creating gaps that are difficult to fill with a seal.

In this context, it is necessary to provide a platform that can be simply fixed to a disc, having a low hub ratio while guaranteeing sufficient clearance at the blade and allowing control of the tightness of the connection with the blade root. .

DISCLOSURE OF THE INVENTION

According to a first aspect, the invention proposes a bladed wheel platform, comprising a vein wall extending in an axial direction by having an upstream end and a downstream end, and comprising two axial stiffeners. The platform comprises radial retention means positioned at the upstream end and at the downstream end of the stream wall, the radial retention means being adapted to each define a slide connection with a corresponding shroud of the bladed wheel and that it comprises tangential retention means adapted to define a sliding pivot connection between the platform and a disk of the bladed wheel.

The tangential retention means may comprise a pin and a lug having a hole adapted to receive the pin, so that the assembly of the lug and the pin forms a sliding pivot connection.

The tab can be fixed to the vein and the pin can be adapted to be fixed to the disk of the bladed wheel.

The radial retention means may comprise an upstream circumferential bearing surface and a downstream circumferential bearing surface, which are adapted to be engaged respectively in an upstream shroud and a corresponding downstream shroud of the bladed wheel.

The vein and the stiffeners can be made of composite materials.

According to a second aspect, the invention relates to an assembly of a bladed wheel disc and a platform, in which the disc receives the platform and has a fitting in which is fixed the pin adapted to be engaged in a sliding pivot connection in the platform leg.

The disk can receive the platform and can comprise at least one downstream ferrule adapted to receive the downstream circumferential bearing and at least one upstream ferrule adapted to receive the upstream circumferential bearing.

According to another aspect, the invention relates to a turbomachine comprising at least one assembly according to the invention.

According to another aspect, the invention relates to an aircraft comprising at least one turbomachine according to the invention.

DESCRIPTION OF FIGURES

Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and not limiting, and which must be read in conjunction with the appended drawings in which:

- Figure 1 is a schematic representation of a bladed wheel of the prior art. - Figure 2 is a perspective representation of the assembly of a platform and a disc according to the invention.

- Figure 3 is a detailed perspective representation of the assembly of an upstream circumferential bearing surface and an upstream shell according to the invention.

- Figure 4 is a detailed perspective representation of the assembly of a downstream circumferential seat and a downstream shroud according to the invention.

- Figure 5 is a detailed perspective representation of the assembly of a pin and a leg of the platform according to the invention.

- Figure 6 is a representation in perspective and in partial section of the assembly of the pin and the leg of Figure 5.

- Figure 7 is a schematic perspective representation of the extraction of a platform according to the invention.

- Figure 8 is a representation of the connection in a pin and a leg according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Bladed wheel background

The invention is positioned in a bladed wheel 1 of a fan. Typically this may be a low pressure compressor fan.

The bladed wheel 1 comprises a disk 2 on which blades 4 are fixed. Platforms 6 are at the interface between the blades 4 and the disk 2 in order in particular to create, via an upper face of the platform, a flow on the inside of vein between the blades near their root which is held in the disc in a conventional alveolus of the disc.

As will be described, the invention relates to the platforms 6 and the disk 2, and more particularly to the connection between the platforms 6 and the disk 2.

Platform

According to a first aspect, the invention proposes a platform 6 of bladed wheel 1. With particular reference to FIG. 2, the platform 6 according to the invention comprises a vein wall 8 which extends in an axial direction. The stream wall 8 has its so-called upper face, opposite the disk, determining a surface shape which promotes fluid flow in a generally longitudinal direction between the vanes on the inner side of the stream. In this case, the duct wall 8 extends in an axial direction between an upstream region and a duct wall 8 makes it possible to promote the flow of air in the fan between the upstream and the downstream of the wheel bladed 1.

In a particularly advantageous manner, the vein wall 8 is made of composite material. This choice of material makes it possible to have a vein wall 8 with optimal curvature. Indeed, the choice of a vein wall 8 made of composite material makes it possible to conform the vein 8 according to a desired surface geometry (as opposed to a sheet which is more difficult to shape). Furthermore, in the case of a blade made of composite material, the vein wall made of composite material is favorable to the lesser aggressiveness of this wall with regard to the blades in the event of a major impact on the latter.

In addition, the platform 6 comprises two axial stiffeners 10. The stiffeners 10 are positioned under the wall of the section 8 to stiffen it. By underside, it is understood that when the platform 6 is fixed to a disc 2, the stiffeners 10 are located between the disc 2 and the vein wall 8. Thus the flow of air can flow over the wall of vein 8 without being disturbed by the stiffeners 10. In other words, the architecture of the platform 6 with a vein 8 stiffened by axial stiffeners 10 very advantageously makes it possible to have a mechanically resistant structure which offers an optimal surface for the flow of air flow.

Preferably the stiffeners 10 can be made of composite material.

In a particularly advantageous manner, the platform 6 comprises on the one hand radial retention means and on the other hand tangential retention means.

Means of radial retention

As shown in particular in Figure 2, the radial retention means are arranged upstream 12 and downstream 14 of the platform 6.

Typically the platform 6 comprises on the one hand radial retention means arranged upstream 12 and on the other hand radial retention means arranged downstream 14. As shown in Figure 3, preferably, the radial retention means comprise an upstream circumferential bearing surface 16, positioned at an upstream end 12 of the platform 6.

It is specified that, by circumferential bearing, it is understood a circumferential rib, that is to say in the shape of an arc of a circle.

As shown in Figure 3 and as described below, the upstream circumferential bearing 16 is adapted to be engaged in a circumferential groove of an upstream shroud 18. The connection between the upstream circumferential bearing 16 and the upstream shroud 18 is preferably a slide-type connection. Thus, by positioning itself in a repository of the bladed wheel 1, using the axial, radial and tangential directions, the connection between the upstream circumferential bearing surface 16 and the upstream shroud 18 limits the degrees of freedom in rotation and prohibits translations in the direction radial. On the other hand, translational movements in the axial direction are permitted. They allow the introduction and extraction of the upstream circumferential bearing 16 in the upstream shroud 18 when assembly or disassembly must be carried out, via the upstream shroud which is removed in these cases. The upstream shroud axially retains the upstream of the platform to block the platform in this direction. In addition, translation movements in the tangential direction are permitted.

As shown in Figure 4, preferably, the radial retention means comprise a downstream circumferential bearing surface 20, positioned at a downstream end 14 of the platform.

As shown in Figure 4 and as described below, the downstream circumferential bearing 20 is adapted to be engaged in a circumferential groove of a downstream shroud 22. The connection between the downstream circumferential bearing 20 and the shroud downstream 22 is preferably a slide-type connection. Thus, by positioning itself in a frame of reference of the bladed wheel 1, using the axial, radial and tangential directions, the connection between the downstream circumferential bearing surface 20 and the downstream shroud 22 limits all the degrees of freedom in rotation and prohibits translations in the radial direction. The downstream shroud axially retains the downstream of the platform to block the platform in this direction. On the other hand, translational movements in the axial direction are permitted on the downstream side when the upstream shroud is removed, for assembly and disassembly operations. They allow in this case the introduction and extraction of the downstream circumferential bearing 20 in the downstream shroud 22. In addition, translational movements in the tangential direction are allowed.

The assembly by circumferential seats, combined with the realization of a composite material vein wall allows to have a very low hub ratio while minimizing the mass of the bladed wheel.

Tangential retention means

Platform 6 also includes tangential retention means.

Preferably, the tangential retention means are adapted to define a sliding pivot connection between the platform 6 and the disc 2 of the bladed wheel 1.

With reference to figures 2, 5, 6 and 8, the tangential retention means comprise a lug 26 and a pin 28. The lug 26 has a hole adapted to receive the pin 28 and thus form a sliding pivot connection with the pin 28.

Preferably, tab 26 is attached to vein wall 8 and pin 28 is attached to disc 2.

The lug 26 can be made of metal and be screwed on the underside of the vein wall

8.

The lug 26 has a portion 26a for attachment to the vein wall 8 of the platform 6 and a connection portion 26b to the disc having the bore 30, this portion being intended to be in connection with a fitting 36. The attachment portion and the portion having the bore 30 are secant. More specifically, with reference to Figure 5, the fixing portion 26a comprises a hooking plate 27a intended to be pressed against and screwed against the vein wall 8. Typically the hooking plate 27a can be screwed to the vein wall 8 by two screws 81. In addition, the fixing portion 26a comprises two half-arch sides 27b. The half-arch sidewalls make it possible to mechanically reinforce the connection between the fixing portion 26a and the connecting portion 26b. By half-arch, it is understood that each flank 27b has a curved edge forming a continuous and progressive connection with the connecting portion 26b. This arrangement makes it possible to optimize the mechanical strength of the lug 26, in particular by maximizing the resistance to bending forces between the fixing portion 26a and the connecting portion 26b. As will be detailed below, the pivot-sliding type connection is a particularly advantageous arrangement of the invention which makes it possible to ensure blocking in the tangential direction while allowing movement in the axial direction. As will be developed below, this arrangement is particularly advantageous in the event of, for example, an impact (such as a bird) on the bladed wheel 1).

Disk

According to another aspect, the invention proposes a disk 2 of bladed wheel 1, adapted to cooperate with a platform 6 according to the invention.

The disc 2 according to the invention has a plurality of fittings 36 each adapted to receive a pin 28, the fittings 36 being radial protuberances. By fitting 36 is meant a tab or a metal tab extending in a radial direction and having a bore 30 adapted to receive a pin 28.

The fitting 36 has a support face connected with the connecting portion 26b of the tab

26.

According to a first embodiment shown in Figures 5 and 6, the support face of the fitting 36 is opposite a support face of the connecting portion 26b, the two support faces being positioned in a radial plane. In other words, according to this first embodiment, the bearing surfaces of the fitting 36 and of the connecting portion 26b are in a plane substantially perpendicular to the axial direction of rotation of the disc 2 and of the wheel bladed 1. According to this embodiment, the fixing portion 26a of the lug 26 and the connecting portion 26b having the bore 30 intersect at an angle substantially different from 90 degrees and defined according to the desired inclination for the vein 8 .

According to a second embodiment, represented in FIG. 8, the two bearing surfaces of the fitting 36 and of the connecting portion 26b are positioned in a plane inclined with respect to a radial plane. In other words, according to this second embodiment, the bearing surfaces are not in a plane substantially perpendicular to the axial direction of rotation of the disk 2 and of the bladed wheel 1. According to this embodiment the portion of attachment 26a of tab 26 and connecting portion 26b having bore 30 intersect at an angle substantially equal to 90 degrees (orthogonal). This second embodiment has the advantage of being simpler to assemble. Indeed, the orthogonal leg 26 facilitates the introduction of tools allowing the leg 26 to be screwed to the vein wall 8. In addition, whatever the embodiment, the pin 28 is fixed to the fitting 36. Preferably, it is linked to the fitting by an embedding-type connection, that is to say that all the degrees of freedom of the piece 28 are blocked.

Preferably the pin 28 is screwed to the fitting 36, as shown in Figures 5 and 6.

Behaviour

The use of a single peg 28 in a sliding pivot connection, in combination with circumferential bearing surfaces, has the advantage of facilitating assembly compared to a multi-peg system, while maintaining a robust system for taking up mechanical forces and positioning the platform.

In addition, in the event of a bird ingestion-type shock, the system coupled by a single pin 28 in a sliding pivot connection and circumferential spans releases degrees of freedom compared to a multi-pin system and simplifies the platform layouts 6 for avoid the risk of damage to the platform 6 during assembly and operation.

The installation of the platform 6 is therefore made easier by the release of these degrees of freedom while maintaining the main function of the pin 28 which is to take up the centrifugal forces.

Indeed, on the one hand, the longitudinal positioning of the fitting 36, substantially mid-length of the disc, and the longitudinal positioning of the tab 26 substantially mid-length of the platform reduces the risk of deformation of the platform 6 under the effect of the centrifugal forces that the platform 6 undergoes during operation.

In addition, the installation of the platform 6 according to the invention involves a shorter assembly kinematics than for the platforms of the prior art, which reduces the clearances necessary, and therefore reinforces the mechanical structure of the connection between the platform 6 and disk 2. It is specified that the clearances required are directly correlated to the displacement required during assembly/disassembly. In the case of the invention, the assembly/disassembly kinematics are reduced, the clearances are therefore reduced accordingly.

Finally, the use of a single pin 28 per platform 6 makes it possible to have a light system (ie lighter than the multi-pin systems of the prior art), which is particularly advantageous in an aeronautical context in which the weight management is an important issue. In addition, as shown schematically in Figure 7, maintenance (ie extraction) of the platform 6 is particularly easy. It suffices to combine a movement of translation to disengage the pin then a movement of rotation around the axial direction to disengage the circumferential bearing surfaces. Together

According to another aspect, the invention relates to an assembly of a disc 2 of a bladed wheel 1 according to the invention and a platform 6 according to the invention, in which the disc 2 receives the platform 6.

Turbomachine According to another aspect, the invention relates to a turbomachine comprising at least one assembly according to the invention.

Aircraft

Claims

1. Platform (6) bladed wheel (1), comprising a vein wall (8) extending in an axial direction having an upstream end and a downstream end, and comprising two stiffeners (10) axial, the platform ( 6) comprising radial retention means (16, 18, 20, 22) positioned at the upstream end and at the downstream end of the stream wall (8), the radial retention means (16, 18, 20, 22) each being adapted to define a sliding connection with a corresponding shroud of the bladed wheel (1), the platform comprising tangential retention means adapted to define a sliding pivot connection between the platform (6) and a disk (2) of the bladed wheel (1).

2. Platform (6) according to claim 1, wherein the tangential retention means (28, 26, 30) comprise a pin (28) and a lug (26) having a bore (30) adapted to receive the pin (28 ), so that the assembly of the tab (26) and the pin (28) forms a sliding pivot connection.

3. Platform (6) according to claim 2, wherein the tab (26) is fixed to the vein (8) and the pin (28) is adapted to be fixed to the disc (2) of the bladed wheel (1).

4. Platform (6) according to any one of the preceding claims, in which the radial retention means (16, 18, 20, 22) comprise an upstream circumferential bearing surface (16) and a downstream circumferential bearing surface (20), which are adapted to be engaged respectively in an upstream shroud (18) and a downstream shroud (22) corresponding to the bladed wheel (1).

5. Platform (6) according to any one of the preceding claims wherein the vein (8) and the stiffeners (10) are made of composite materials.

6. Assembly of a disc (2) bladed wheel (1) and a platform (6) according to claim 3, wherein the disc (2) receives the platform (6) and has a fitting (36) in which is fixed the pin (28) adapted to be engaged in sliding pivot connection in the leg (26) of the platform.

7. Assembly of a disc (2) bladed wheel (1) and a platform (6) according to claim 4, wherein the disc (2) receives the platform (6) and comprising at least one downstream shroud ( 22) adapted to receive the downstream circumferential bearing (20) and at least one upstream shroud (18) adapted to receive the upstream circumferential bearing (16).

8. Turbomachine comprising at least one assembly according to claim 7.

9. Aircraft comprising at least one turbomachine according to claim 8.