Patent Application
20050063826
The invention relates to the turbine engines sector, and more particularly that of inter-vane platforms for support disks for vanes of turbine engine fans.
The fans of a turbine engine, of which the vanes present a curvilinear foot, generally comprise support disks for vanes which are equipped with detachable inter-vane platforms intended to optimize the flow of air between the vanes, and, more precisely, to reconstitute the dynamic profile of the internal jet at the level of the vanes, in particular if they are of large chord.
A detachable platform usually comprises a deflecting part, of which the lower face comprises at least one securing foot (and more generally two or three), intended to allow for its connection to another securing foot of a support disk by means of a securing pin.
The securing pins conventionally have the shape of a rod provided with a first threaded part, having a first diameter, and extended by a second part that constitutes a head, having a second diameter greater than the first. In order to connect the securing feet to one another, the securing pin is first secured on the securing foot of the support disk, immobilizing it by means of a nut. The platform is then slid in the direction of the securing pin until the head of said pin penetrates into the aperture in the securing foot of the platform. The head of the pin is then lodged in the aperture of the securing foot of the platform, while projecting out from it. Due to this method of assembly, the nut is hard to access.
Because the detachable platform is subjected to a centrifugal force, each securing pin undergoes flexure and shear stress. Due to the method of connection and function of the securing pin, only the threaded section of the rod operates simultaneously in flexure and shear. In consequence, it is the part of the securing pin that has the smallest diameter, and therefore the lowest strength, which is subjected to the highest stress.
In order to improve the strength of the pins, it might be possible to envisage increasing the diameters of their various parts, but this is not possible for reasons of space.
The object of the invention is therefore to overcome all or part of the above disadvantages.
To achieve this, the invention proposes an inter-vane platform for a vane support disk of a fan of a turbine engine, comprising a deflecting part, in turn comprising a lower face provided with at least one first securing foot (or flange), comprising at least one aperture for the passage of a securing pin intended to connect it between two adjacent vanes to a second securing foot (or flange) of the support disk.
This platform, made preferably of a metal or composite material, is characterized by the fact that each securing pin comprises a rod, provided with a threaded first part, which has a first selected diameter intended to receive a bolt intended for the connection, and a second part comprising a first sub-part serving to extend the first part and having a second diameter, greater than the first diameter, and a second sub-part extending the first sub-part and having a third diameter smaller than the second diameter, in such a way as to be able to pass through the aperture of the first securing foot.
The first sub-part of the rod is therefore interleaved between the first and second securing feet, including when it is subjected to stress in flexure. This arrangement is therefore optimum, since it allows for the flexural stresses to be supported by the portion of the rod that has the greatest diameter and shear stresses in comparison with the two other portions.
In addition to this, the diameters of each of the portions of the rod can also be selected as a function of the stresses specific to the environment of the platform.
Accordingly, a rod can be envisaged which comprises first and third diameters that are substantially identical or different.
In addition to this, the aperture in the first securing foot preferably has an internal diameter that is substantially equal, by higher value, to the third diameter, so that the second sub-section of the rod is in close contact with said first securing foot. In order to improve this contact still further, the aperture of the first securing foot may accommodate a disconnected element (or sleeve or another insert), defining the internal diameter.
The invention likewise relates to a vane support disk comprising a plurality of inter-vane platforms of the type presented above and interlaced respectively between the pairs of adjacent vanes.
Other features and advantages of the invention will become apparent on examination of the detailed description below and of the appended drawings, in which:
The appended drawings can serve not only to supplement the invention, but also contribute to its definition, as applicable.
The invention relates to an inter-vane platform intended to equip a vane support disk for a fan of a turbine engine equipped with vanes with curvilinear feet (also referred to as “wide chord” vanes).
As is partially illustrated in
Each detachable platform 3 is, more precisely, installed on the support disk 1, between two adjacent vanes 2, in such a way as to restore the aerodynamic profile of the internal jet at the level of the vanes.
A platform 3 according to the invention, as illustrated in diagrammatic form in
The first securing pin 8 is intended to connect the first securing foot 6 to a third securing foot (or flange) 12 of an element 13 of the support disk 1, which for this purpose is provided with a third aperture 14. Likewise, the second securing pin 11 is intended to connect the second securing foot 9 to a fourth securing foot (or flange) 15 of the element 13, which is provided for this purpose with a fourth aperture 16.
As is better illustrated in
Each securing pin 8 and 11 additionally comprises a nut 22, intended to be screwed onto the first threaded part 20 of the rod 17 in such a way as to render it as one piece with one of the securing feet 12 or 15 of the element 13.
The first diameter D1 of the first threaded part 18 of the rod 17 (for example, of the first securing pin 8) is substantially equal, by lower value, to the diameter of the third aperture 14 of the third securing foot 12 of the element 13. In addition to this, the third diameter D3 of the second sub-section 21 of the rod 17 (for example, of the first securing pin 8) is substantially equal, by lower value, to the inner diameter of the first aperture 7 of the first securing foot 6 of the platform 13.
In the example shown, the first aperture 7 accommodates a sleeve (or insert) 23, preferably metallic, intended to avoid the second sub-part 21 (or head) from being damaged due to the stresses imposed on it.
Thanks to this arrangement, once the rod 17 is installed its first sub-part 20 is located interlaced between a “front” face (or in this case the left-hand side) of a securing foot (for example, the third 12) of the element 13, and a “rear” face (in this case the right-hand side) of a securing foot (for example, the first 6) of the platform 3. More precisely, the first sub-part 20 (or collar) defines the first and second support surfaces, substantially flat, intended to support one another respectively against the front face of the (third) securing foot (12) and the rear face of the (first) securing foot (6), which are substantially flat, at least locally.
At the same time, the first threaded part 18 of the rod 17 passes through the (third) aperture (14) of the (third) securing foot (12) and opens to the outside of the side of its rear face, and the second sub-part 21 passes through the (first) aperture of the (first) securing foot (6) and opens to the outside of the side of its front face. The front face (substantially flat) of the nut 22, screwed onto the first threaded part 18 of the rod 17, is therefore supported on the rear face of the (third) securing foot (12) of the element 13, which is substantially flat, at least locally.
Because the platform 3 is principally subject to a centrifugal force, represented by the arrow F, it is therefore, thanks to the invention, the first sub-part 20 (or collar) of its securing pins 8 and 11 which is subjected to the flexure stresses, while the first threaded part 18 and the second sub-part 21 of said securing pins undergo shearing stresses.
This is particularly advantageous since it is the first sub-part 20 (or collar) which has the largest diameter (D2) within the rod 17 that supports the greatest stresses. In consequence, the diameter of the collar 20 is preferably chosen to be as large as possible. The same applies to its thickness (according to the axis of the pin).
In addition to this, thanks to the invention, it is possible to choose diameters (D1 to D3) of the rods 17 of the securing pins 8 and 11 as a function of the stresses specific to the environment of the platform 3. Accordingly, as illustrated in
The invention is not limited to the embodiments of the inter-vane platform and vane support disk described above, only by way of example, but encompasses all the variants which the person skilled in the art could envisage within the framework of the claims hereafter.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0309450 | Jul 2003 | FR | national |
