Inter-blade platform seal

Abstract

Seal (10) for an inter-blade platform intended to extend circumferentially about an axis and to be mounted between two axial ends of the inter-blade platform, including a first part (10a) in contact with a first blade adjacent to a first circumferential end of the platform, and a second part (10b) in contact with a second blade adjacent to a second circumferential end of the platform, the first part (10a) and the second part (10b) of the seal (10) being fixed to each other such that a displacement in the circumferential direction of one of the two parts (10a, 10b) of the seal (10) causes a displacement of the other part (10a, 10b) of the seal (10) in the same direction, when the two parts (10a, 10b) of the seal (10) are fixed to each other.

Claims

1. An inter-blade platform comprising a seal configured to extend circumferentially about an axis and to be mounted between two axial ends of the inter-blade platform, the seal comprising at least a first part configured to be in contact with a first blade circumferentially adjacent to a first circumferential end of the platform, and at least a second part configured to be contact with a second blade circumferentially adjacent to a second circumferential end of the platform, the first part and the second part of the seal being distinct from each other and being configured to be fixed to each other such that a displacement in one circumferential direction of one of the first or second part of the seal causes a displacement of the other one of the first or second part of the seal in the same direction, when the first part and the second part of the seal are fixed to each other, wherein a first structural portion and/or a second structural portion of the seal comprises at least one tab, and the inter-blade platform comprises a box delimited by a flowpath wall to define an air flowpath, the box comprising at least one lateral passage, wherein the at least one lateral passage is an orifice formed in a lateral wall of the box configured to accommodate the at least one tab and to allow displacement of the seal extending on either side of the platform in a circumferential direction, radially under the flowpath wall.

2. The inter-blade platform according to claim 1, wherein the first part of the seal comprises a first contact portion made of elastomeric material, the first contact portion being configured to be in contact with the first circumferential end of the platform and the first blade circumferentially adjacent to the first circumferential end of the platform, and the second part of the seal comprises a second contact portion made of elastomeric material, the second contact portion being configured to be in contact with the second circumferential end of the platform and the second blade circumferentially adjacent to the second circumferential end of the platform.

3. The inter-blade platform according to claim 1, wherein the first part of the seal comprises the first structural portion, and the second part of the seal comprises the second structural portion, the first structural portion and the second structural portion being configured to be assembled with each other.

4. The inter-blade platform according to claim 3, wherein each of the first and second structural portions comprises a metal material.

5. The inter-blade platform according to claim 3, wherein the at least one tab extends circumferentially, one circumferential end of the at least one tab being configured to come into contact with the other one of the first and second structural portions.

6. The inter-blade platform according to claim 5, wherein the first part of the seal comprises at least a first attachment part fixed to at least one tab of the first structural portion, and the second part of the seal comprises at least a second attachment part fixed to at least one tab of the second structural portion, the first and second attachment parts being configured to cooperate together so as to assemble the first part of the seal to the second part of the seal.

7. A rotor comprising a disk at the periphery of which a plurality of blades and a plurality of inter-blade platforms according to claim 1 are mounted, each platform being disposed between each pair of circumferentially adjacent blades.

8. A turbomachine comprising a rotor according to claim 7.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its advantages will be better understood upon reading the detailed description below of various embodiments of the invention given by way of non-limiting examples. This description refers to the pages of appended figures, in which:

(2) FIG. 1 represents a schematic sectional view of a turbojet engine according to the invention,

(3) FIG. 2 represents a schematic view along the direction II of the fan of FIG. 1,

(4) FIG. 3 represents a partial view of a section of a fan according to the prior art,

(5) FIG. 4A schematically represents a bottom view of a seal according to the invention when the first and second parts of the seal are joined, and FIG. 4B represents a bottom view of a seal according to the invention when the first and second parts of the seal are disjointed,

(6) FIG. 5A represents a perspective view of a first and a second attachment part of the seal according to the invention in the locked position, FIG. 5B represents a perspective view of a first and a second attachment part of the seal according to the invention in the unlocked position, and FIG. 5C represents a front view of a first and a second attachment part of the seal according to another example of the invention in the locked position,

(7) FIG. 6A represents a perspective view of a platform according to the invention, and FIG. 6B represents a lateral section of the platform of FIG. 6A according to a section plane VIB-VIB,

(8) FIG. 7 represents a sectional view along a plane parallel to the circumferential direction of the platform according to the invention.

DESCRIPTION OF THE EMBODIMENTS

(9) In the present disclosure, the term “axial” and its derivatives are defined in relation to the main direction of the considered seal and platform; the term “circumferential” and its derivatives are defined in relation to the direction that extends about the axial direction; the terms “radial”, “internal”, “external” and their derivatives are for their part defined in relation to the main axis of the turbomachine, when the platform is mounted on a disk which is in turn mounted in the turbomachine; finally, the terms “above”, “below”, “lower”, “upper” and their derivatives are defined in relation to the radial direction facing the axis about which the turbomachine extends. Also, unless otherwise indicated, the same reference signs in different figures refer to the same characteristics.

(10) FIG. 1 shows a schematic longitudinal sectional view of a bypass turbomachine 1 centered on the axis A about which the turbomachine extends. It includes, from upstream to downstream: a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, and a low-pressure turbine 7.

(11) FIG. 2 shows a schematic view of the fan 2 of FIG. 1 along the direction II. The fan 2 comprises a fan disk 40 in which a plurality of grooves 42 are made at its external periphery. These grooves 42 are rectilinear and extend axially from upstream to downstream all along the disk 40. They are further evenly distributed all about the axis A of the disk 40. In this way, each groove 42 defines with its neighboring one a tooth 44 which also extends axially from upstream to downstream all along the disk 40. In an equivalent manner, a groove 42 is delimited by two circumferentially adjacent teeth 44.

(12) The fan 2 further comprises a plurality of blades 20 of curvilinear profile (only four blades 20 have been represented in FIG. 2). Each blade 20 has a root 20a which is mounted in a respective groove 42 of the fan disk 40. For this purpose, the root 20a of a blade 20 may have a fir tree or dovetail shape adapted to the geometry of the grooves 42, each root 20a having a shape at least partly complementary to the shape of the groove 42 in which it is mounted.

(13) Finally, the fan 2 comprises a plurality of added platforms 30, each platform 30 being mounted in the interval that extends circumferentially between two adjacent fan blades 20, in the vicinity of the root 20a thereof, in order to delimit, on the internal side, an annular flowpath for entering air in the fan 2, the flowpath being delimited on the external side by a fan casing (not represented).

(14) As illustrated in FIG. 3, each edge, or circumferential end 32a, 32b, of each platform 30, respectively facing the intrados 22a side and the extrados 22b side of a blade 20, is respectively equipped with a seal 100 and with a seal 100′ according to the prior art, extending along said circumferential ends 32a, 32b in the axial direction. In this example, the seal 100 is configured to cooperate with the blade 20 on the intrados 22a side while the seal 100′ is configured to cooperate with the blade 20 on the extrados 22b side. A movement of a first blade 20 (the one on the left in FIG. 3) in the circumferential direction Y tends to exert a pressure on the seal 100. Conversely, a movement of a second blade 20 (the one on the right in FIG. 3) in the same circumferential direction Y tends to move this blade 20 away from the seal 100′ (arrow in FIG. 3).

(15) FIGS. 4A and 4B schematically represent a bottom view of a seal 10 according to the invention when the first and second parts of the seal are joined (FIG. 4A) and disjointed (FIG. 4B). The axis X represents the axial direction, and the axis Y represents the circumferential direction. When the seal 10 is mounted on a platform 30 which is in turn mounted on a fan disk, the axis X is substantially parallel to the central axis A of the turbojet engine. In these figures, the circumferential ends of the seal 10 have a rectilinear shape in the axial direction X. This illustration is schematic, with the seal 10 not limited to this shape. On the contrary, the circumferential ends of the seal 10 may have a curved shape, so as to fit the shape of the profile of the blade with which they are in contact when the seal 10 is mounted on a fan platform. Furthermore, the face of the seal 10 illustrated in FIGS. 4A and 4B, in this bottom view, is the face directed towards the axis of the fan when the seal 10 is mounted on a fan platform, in other words, the radially inner face of the seal 10.

(16) The seal 10 comprises a first part 10a and a second part 10b, separate from the first part 10a. The first part 10a comprises a first contact portion 12a, and a first structural portion 14a, fixed to each other, for example by bonding. Similarly, the second part 10b comprises a second contact portion 12b, and a second structural portion 14b, fixed to each other, for example by bonding. The contact portions 12a, 12b each comprise an elastomeric material, and are provided to be in contact, respectively, with the circumferential end 32a of the platform 30 and a blade adjacent to said circumferential end 32a, and the circumferential end 32b of the platform 30 and a blade adjacent to said circumferential end 32b.

(17) The structural portions 14a, 14b each comprise a metal material, for example an aluminum alloy, and may also include a carbon composite. Alternatively, the structural portions may include an elastomer having an embedded part made of aluminum alloy or be entirely metallic, made of aluminum or titanium alloy. In the example illustrated in FIGS. 4A and 4B, the first structural portion 14a comprises three tabs 140a, and the second structural portion 14b also comprises three tabs 140b. The circumferential ends 141a of the tabs 140a of the first structural portion 14a are configured to come into contact with the circumferential ends 141b of the tabs 140b of the second structural portion 14b, when the first and second parts 10a, 10b of the seal are assembled. According to this embodiment, the tabs 140a of the first structural portion 14a are shorter, in the circumferential direction, than the tabs 140b of the second structural portion 14b. However, the seal 10 is not limited to this structure. The tabs 140a, 140b may for example have an equal length. Similarly, the dimension of the tabs along the axial direction X is given as an illustration in FIGS. 4A, 4B, and may vary according to the structure of the platform 30 on which the seal 10 is mounted. The number of these tabs may also vary, and may be less than or greater than three for each structural portion 14a, 14b, each tab 140a of the first structural portion 14a having to face, along the circumferential direction Y, a tab 140b of the second structural portion 14b.

(18) Furthermore, the seal 10 includes a first attachment part 16a fixed to a tab 140a of the first structural portion 14a, and a second attachment part 16b fixed to a tab 140b of the second structural part 14b. These attachment parts 16a, 16b are fixed on a radially inner face of the seal 10, when the latter is mounted on a fan platform 30. In FIG. 4A, a single pair of attachment parts 16a, 16b is illustrated. Nevertheless, a first attachment part 16a may be provided on both or each tab 140a of the first structural portion 14a. Similarly, a second attachment part 16b may be provided on both or each tab 140b of the second structural portion 14b.

(19) FIGS. 5A et 5B represent a perspective view of a first and a second attachment part 16a, 16b of the seal 10 according to the invention, when these are in the locked position and in the unlocked position, respectively. The first attachment part 16a comprises a first attachment portion 161a fixed to the tab 140a, for example by welding, and a first pin part 162a comprising a first branch 162a1 extending in the circumferential direction from the fixing portion 161a, and a second branch 162a2 extending from the circumferential end of the first branch 162a1 toward the attachment portion 161a. The second attachment part 16b comprises a second fixing portion 161b fixed to the tab 140b, for example by welding, and a second pin part 162b comprising a first branch 162b1 extending in the circumferential direction from the fixing portion 161b, and a hook 162b2 extending from the first branch 162b1 such that the end of the hook 162b2 is directed toward the fixing portion 161b.

(20) When the first and second parts 10a, 10b of the seal 10 are brought closer to each other, the second branch 162a2 of the first pin part 162a slides along the hook 162b2 of the second pin part 162b, by elastically deforming so as to come closer to the first branch 162a1. When the first and second parts 10a, 10b of the seal 10 are brought further closer to each other, such that the circumferential ends 141a and 141b of the tabs 140a, 140b abut against each other along a contact surface 141, the end of the second branch 162a2 of the first pin part 162a passes over the hook end 162b2 by again moving away from the first branch 162a1, when the first pin part 162a returns to its initial shape. The first and second attachment parts 16a, 16b are thus in the locked position, and the first and second parts 10a, 10b are then joined to each other. It is also possible to separate the two parts 10a, 10b from each other, by exerting a force on the first part 10a in the axial direction X, so as to release the second branch 162a2 from the hook 162b2.

(21) FIG. 5C represents a perspective view of a first and a second attachment part 17a, 17b of the seal 10 of the invention according to an alternative example, when these are in the locked position. The first attachment part 17a comprises a first attachment portion 171a fixed to the tab 140a, for example by welding, and a first notched part 172a extending in the circumferential direction from the fixing portion 171a, the first notched part 172a including a first step 172a1 extending perpendicular to the circumferential direction. The second attachment part 17b comprises a second fixing portion 171b fixed to the tab 140b, for example by welding, and a second notched part 172b extending in the circumferential direction from the fixing portion 171b, the second notched part 172b including a second step 172b1 extending perpendicular to the circumferential direction.

(22) When the first and second parts 10a, 10b of the seal 10 are brought closer to each other, an inclined wall of the first notched part 172a slides along an inclined wall of the second notched part 172b, by both deforming elastically. When the first and second parts 10a, 10b of the seal 10 are brought further closer to each other, such that the circumferential ends 141a and 141b of the tabs 140a, 140b abut against each other according to the contact surface 141, the first step 172a1 passes over the second step 172b1, such that the first and second notched parts are hooked to each other. The first and second attachment parts 17a, 17b are thus in the locked position, and the first and second parts 10a, 10b are then joined to each other.

(23) FIG. 6A represents a perspective top view of a platform 30 according to the invention, on which a seal 10 is mounted, and FIG. 6B represents a lateral section of the platform of FIG. 6A along a section plane VIB-VIB. The platform 30 includes a box 32 for maintaining in position the flowpath wall 34, and also limiting its deformations under the effect of centrifugal forces. The box 32 also includes a bottom surface 36 that can bear against a tooth 44 of the disk 40 of the fan. The box 32 includes lateral passages 38 in its radially external part, radially under the flowpath wall 34. Each structural portion 14a, 14b includes as many tabs 140a, 140b as there are passages 38. When the seal 10 is mounted on the platform 30, the first part 10a is inserted radially under the flowpath wall 34 from a circumferential end 32a of the platform 30, by passing the tabs 140a through the passages 38. Similarly, the second part 10b is inserted radially under the flowpath wall 34 from the other circumferential end 32b of the platform 30, by passing the tabs 140b through the passages 38, until the lateral ends 141a, 141b come into contact with each other along the contact surface 141, and the first and second attachment parts 16a, 16b are in the locked position.

(24) FIG. 7 represents a sectional view along a plane parallel to the circumferential direction of the platform 30, at a passage 38. According to this embodiment, the contact portions 12a, 12b have a rectangular section. However, this shape is not limiting, other shapes allowing the contact portions 12a, 12b to slide partly radially under the flowpath wall 34 are conceivable. The contact portions may for example have a flared shape toward the area of contact with the blade, or a substantially T-shape, as illustrated in FIG. 3. When the blades 20 (not illustrated in FIG. 7) move in the direction of the arrows in FIG. 7, a blade 20 exerts a force on the contact portion 12a, and therefore on the structural portion 14a. This force is transmitted to the structural portion 14b via the contact surface 141 at the ends of the tabs. A displacement of the entire seal 10 is thus generated, the seal 10 sliding under the flowpath wall 34 by passing through the passages 38. The resulting displacement of the contact portion 12b, in the direction of the arrow in FIG. 7 thus allows compensating for the movement of the blade 20 in the same direction, and thus maintaining the sealing function of the contact portion 12b, between the circumferential end 32b of the platform and the blade 20.

(25) Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. Particularly, individual characteristics of the various illustrated/mentioned embodiments can be combined in additional embodiments. Consequently, the description and drawings should be considered in an illustrative rather than restrictive sense.