Anti-injury sealing housing for mobile blade stilts for turbojet engines
The sealing box design with curved edges and elastomer coating addresses the issue of stilt damage by turbojet engine sealing boxes, enhancing durability and reducing maintenance costs.
Patent Information
- Application Number
- FR2024002622
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2024-03-15
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2044-03-15
AI Technical Summary
Conventional sealing boxes for turbojet engines cause damage to the stilts of movable blades due to plane-on-plane contact, leading to premature aging and increased maintenance costs.
A sealing box design with curved edges and optional elastomer coating to prevent direct contact with stilts, providing a non-injurious interface through curved and flat surfaces that accommodate centrifugal forces.
Prevents stilt damage, reduces maintenance needs, and extends the lifespan of the sealing boxes by ensuring a non-damaging contact with the movable blades.
Smart Images
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Abstract
Description
Title of the invention: Anti-injury sealing housing for a movable blade stilt for a turbojet engine TECHNICAL FIELD OF THE INVENTION
[0001] The technical field of the invention is that of sealing boxes intended to be housed between the struts of two movable blades of a turbojet engine in order to prevent the circulation of air between the platforms of said movable blades.
[0002] The present invention relates to a new sealing box designed not to injure Péchasse of the moving blades against which it rests. TECHNOLOGICAL BACKGROUND OF THE INVENTION
[0003] A conventional sealing box 1' is shown in perspective in [Fig. 1] and [Fig. 2], where it is positioned against the Péchasse 2 of a movable blade 3 of a turbojet engine. On the outer side with respect to the longitudinal axis X along which the turbojet extends, Péchasse 2 has a platform 4 equipped with a blade 5, while on the inner side, Péchasse 2 terminates in a bulb 6, serving as a mounting base for a rotor disk 7. On the outer side, the sealing box 1' has a substantially flat upper face 8' designed to close the gap between the platforms 4 of two adjacent movable blades 3. Thus, a sealing box 1' is provided on each side of the Péchasse 2 of a movable blade 3, between the bulb 6 and the platform 4.
[0004] A sealing box 1' is a hollow part, usually made of pre-formed sheet metal, whose external shape is designed to substantially conform to that of the struts 2 against which it rests. While the upper face 8' of a sealing box 1' is closed, its lower part usually has an opening 9' delimited by sides 10'. In use, the opening 9' of a sealing box 1' is open in the direction of the longitudinal axis X, while its upper face 8' is located on the side opposite this axis.
[0005] At the opening 9', the sides 10' of a sealing box 1' are bordered by an external edge 11' and by an internal edge 12'. In use, part of the external edge 11' is in contact with a stilt 2 of a moving blade 3 and it has been found that this contact sometimes damages said stilt 2 on the surface, generating grooves that can be designated as indications.
[0006] These injuries are undesirable because they cause premature aging of the stilts 2. They require maintenance operations, which result in equipment downtime and additional costs.
[0007] There is therefore a need for a sealing box that does not injure Péchasse of a moving blade against which it is in contact. Summary of the invention
[0008] To address this problem, the applicant conducted extensive preliminary research aimed at understanding the exact origin of these injuries. Indeed, when a conventional sealing box 1' is in place (see [Fig. 5], [Fig. 6], and [Fig. 7]), the outer edge 11' is not in contact with a stilt 2' in such a way as to damage it. During assembly, the contact between the side 10' of the box 1' and a face of the stilt 2' is of the plane-on-plane type.
[0009] It has been discovered that in use, under the effect of centrifugal force, the box 1' pivots slightly and the contact of the side 10' of the box against a face of the stilt 2' becomes linear, so that the external edge 11' is in contact with said stilt 2' so as to injure it (cf. [Fig.8], [Fig.9] and [Fig. 10]).
[0010] The invention offers a solution to the aforementioned risk of injury problems by providing a dropped edge at least along the edges of the sealing box that are likely to come into contact with a stilt. The sealing box according to the invention is designed to replace the conventional sealing box of the previous Fart without requiring any modification to the moving blades between which it is used.
[0011] One aspect of the invention relates to a sealing assembly for two adjacent movable blades within the same rotor stage of a turbojet engine, said turbojet engine extending longitudinally along an axis X, the sealing assembly comprising: • a first foot of a first movable blade, comprising a first platform equipped with a first stilt extending radially towards the X axis; • a second foot of a second movable blade comprising a second platform equipped with a second stilt extending radially towards the X-axis, the second platform being located opposite and in line with the first platform; and • a sealing box located between the first and second legs and having: • a closed upper face in contact with an underside of at least one platform among the first and second platforms, • sides extending downwards from the upper face and ending in a free edge that defines an opening in the lower part of the sealing box, a first side being in contact with the first stilt, and a second side being located opposite the first side; and in which • at its free edge, the first side has a part that curves inwards towards the sealing box.
[0012] Advantageously, the curved part provides a contact area between the sealing box and a stilt which is not likely to injure said stilt, whether the sealing box is pressed parallel against this stilt (see [Fig. 13] and [Fig. 14]) or whether it is slightly pivoted under the effect of centrifugal force (see [Fig. 15] and [Fig. 16]).
[0013] According to one aspect of the invention, the first side has a substantially flat portion located between its curved part and the closed upper face. This flat portion advantageously provides a large bearing surface for securing the sealing box against Péchasse without damaging it.
[0014] According to another aspect of the invention, the substantially flat part of the first side is parallel to a face of the first stilt located opposite, which advantageously allows us to take advantage of the large support surface so as not to injure Péchasse.
[0015] According to an additional aspect of the invention, at its free edge, the second side also has a part curved towards the inside of the sealing box, which advantageously prevents injury to the second stilt if the sealing box comes into contact with it.
[0016] According to one aspect of the invention, at the level of their free edge, all the sides have a part curved towards the inside of the sealing box, which advantageously prevents injury to either of the stilts, whether the sealing box is pivoted or not.
[0017] According to another aspect of the invention, the second side has a substantially flat part which is parallel to a face of the second stilt located opposite, which advantageously allows a large support surface to be used so as not to damage the second stilt.
[0018] According to a further aspect of the invention, an external face of at least one curved part is coated with a layer of elastomer.
[0019] According to one aspect of the invention, an external face of all curved parts is coated with a layer of elastomer.
[0020] This elastomeric coating advantageously provides protection against friction and wear.
[0021] According to another aspect of the invention, an elastomer layer has an average thickness of between 0.1 and 5 mm, preferably between 0.2 and 2 mm, more preferably between 0.3 and 1 mm. The thinness of this layer makes it possible, in particular, not to significantly alter the external shape of the sealing box.
[0022] According to a further aspect of the invention, the sealing box has a average thickness of 0.5 ± 0.05 mm.
[0023] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES
[0024] The figures are presented for illustrative purposes only and are in no way limiting of the invention.
[0025] [Fig.l] is a perspective view from below of a sealing box according to the prior art.
[0026] [Fig.2] is a perspective view from below of a sealing box according to art anterior positioned against Péchasse and under a platform of a mobile paddle represented in discontinuous lines.
[0027] [Fig.3] is a top perspective view of two sealing boxes according to art anterior positioned against both sides of a stilt of a mobile paddle represented in discontinuous lines.
[0028] [Fig.4] is a radial cross-sectional view of a sealing box according to the prior art positioned between two moving blades.
[0029] [Fig.5] is a detail view of the part circled in [Fig.4].
[0030] [Fig.6] is a view similar to [Fig.4] where the sealing box is pivoted under the effect of centrifugal force.
[0031] [Fig.7] is a detail view of the part circled in [Fig.6].
[0032] [Fig.8] is a perspective view from below of an example of a sealing box according to the invention.
[0033] [Fig.9] is a cross-sectional view along the radial plane shown in dashed lines on [Fig.8] of the framed part on [Fig.8].
[0034] [Fig. 10] is a perspective view from below of an example of a sealing box according to the invention, all of whose curved parts are coated with a layer of elastomer.
[0035] [Fig.11] is a detail view of the framed part in [Fig.10].
[0036] [Fig. 12] is a cross-sectional view along the radial plane shown in dashed lines on [Fig.1 1] of the framed part on [Fig.10].
[0037] [Fig. 13] is a radial cross-sectional view of an example of a sealing box according to the invention positioned between two movable blades.
[0038] [Fig.14] is a detail view of the part circled in [Fig.13].
[0039] [Fig. 15] is a view similar to [Fig. 13] where the sealing box is pivoted under the effect of centrifugal force.
[0040] [Fig. 16] is a detail view of the part circled in [Fig. 15].
[0041] [Fig. 17] is a view similar to [Fig. 13] where the sealing box has sides opposite parallel to the stilts between which it is positioned, one of the flanks being in leaning against one of the stilts.
[0042] [Fig. 18] is a view similar to [Fig. 17] where both sides are each supported against one of the stilts.
[0043] [Fig. 19] is a detail view of the part circled in [Fig. 18].
[0044] [Fig.20] is a detail view of the part circled in [Fig. 18]. DETAILED DESCRIPTION
[0045] Unless otherwise specified, the same element appearing on different figures has a unique reference.
[0046] By convention, in this application, the terms "upper" and "lower," and "top" and "bottom" refer to the elements as shown in the figures, it being understood that this arrangement will not necessarily be maintained in use. These terms are defined radially with respect to the longitudinal axis of the turbojet engine. Thus, a cylindrical part extending along the axis of the turbojet engine has a lower face facing the longitudinal axis X of the turbojet engine and a upper surface opposite its inner surface. Similarly, the lower part of a part is a portion located on the inner side with respect to the longitudinal axis X along which the turbojet engine extends and therefore in the direction of this axis, while the upper part of a part is a portion located on the outer side with respect to the longitudinal axis X and therefore away from this axis.Finally, the "external" or "internal" face of a part of the sealing box refers to a face oriented respectively towards the outside or the inside of said box.
[0047] The sealing box 1 according to the invention is intended to be positioned between the stilts 2 of two adjacent movable blades 3 within the same rotor stage of a turbojet engine, said turbojet engine extending longitudinally along an axis X.
[0048] In a conventional manner, each movable blade 3 comprises at least one platform 4 equipped with a blade 5 extending radially outwards with respect to the axis X and a bulb 6 extending radially inwards with respect to the axis X, a strut 2 connecting the platform 4 to the bulb 6. The strut 2 and the bulb 6 form the foot 13 of a movable blade 3.
[0049] The sealing assembly according to the invention is intended to limit the circulation of air between two adjacent movable blades 3, 3a, 3b within the same rotor stage of a turbojet engine.
[0050] This sealing assembly includes: • a first foot 13a of a first movable blade 3a, comprising a first platform 4a equipped with a first stilt 2a extending radially towards the X axis; • a second foot 13b of a second movable blade 3b comprising a second platform 4b equipped with a second stilt 2b extending radially towards the X-axis, the second platform 4b being located opposite and in line with the first platform 4a; and • a sealing box 1 according to the invention, intended to be positioned between the first and second feet 13a, 13b.
[0051] Conventionally, the sealing box 1 according to the invention has a closed upper face 8, designed to be positioned in contact with a lower face 14, 14a, 14b of at least one platform 4 among the first and second platforms 4a, 4b. It also has sides 10, extending downwards from the upper face 8 and terminating in a free edge 15 which defines an opening 9 in the lower part of the sealing box 1, a first side 10a being in contact with the first stilt 2a, and a second side 10b being located opposite the first side 10a. This second side 10b may be in contact with the second stilt 2b or be at a distance from it.
[0052] The sealing housing 1 is, for example, made of metal, preferably stainless steel and more preferably Z10CNT18 steel. Its upper face 8 and sides 10 have, for example, an average thickness E on the order of half a millimeter, preferably 0.5 ± 0.05 mm. The average thickness of the walls 8, 10 of the sealing housing 1 is understood to be the average between the minimum and maximum thicknesses of said walls 8, 10. This thickness can be greater to accommodate all engine sizes and meet mechanical resistance requirements.
[0053] As shown in [Fig.8] to [Fig.20], the sealing box 1 according to the invention is distinguished in that, at the level of its free edge 15, at least the first flank 10a has a curved part 16, 16a towards the inside of the sealing box 1.
[0054] The free edge 15 comprises an external edge 11, located on the outer side of the sealing box 1, and an internal edge 12 located on the inner side. Due to the curvature of the free edge 15, the external edge 11 cannot come into contact with a stilt 2, even when the sealing box 1 is rotated under the effect of centrifugal force.
[0055] According to a variant of the invention, the second flank 10b may also have a curved part 16, 16b towards the inside of the sealing box 1 at the level of its free edge 15.
[0056] According to another variant of the invention shown in [Fig.8] to [Fig.20], all the sides 10, 10a, 10b of the sealing box 1 may have a curved part 16, 16a, 16b towards the inside of the sealing box 1 at the level of their free edge 15.
[0057] According to a variant of the invention, an external face 17 of at least one curved part 16 is coated with a layer of elastomer 18.
[0058] According to another embodiment of the invention, an external face 17 of all the parts curved 16, 16a, 16b is coated with a layer of elastomer 18.
[0059] According to a preferred embodiment of the invention shown in [Fig.10] to [Fig.12], the entirety of all the curved parts 16, 16a, 16b is coated with a layer of elastomer 18, both on their outer face 17 and on their inner face 19.
[0060] This elastomer layer 18 is, for example, deposited by dipping the curved parts 16, 16a, 16b of the sealing box 1 into a bath of liquid elastomer and then solidifying the elastomer layer 18 thus deposited. According to a preferred embodiment of the invention, the addition of the elastomer layer 18 is carried out by dipping and open-air polymerization according to the process known as room temperature vulcanization (RTV).
[0061] The elastomer layer 18 is preferably designed to withstand a temperature between 205 °C and 315 °C.
[0062] The elastomer layer 18, for example, has an average thickness e on the order of half a millimeter. The average thickness e is preferably between 0.1 and 5 mm, preferably between 0.2 and 2 mm, and more preferably between 0.3 and 1 mm. The average thickness of the elastomer layer 18 is understood to be the average of the minimum and maximum thicknesses of said elastomer layer 18.
[0063] According to an example of the invention, the first side 10a has a substantially flat portion 20a situated between its curved portion 16a and the closed upper face 8. This substantially flat portion 20a is preferably parallel to the face 21a of the first stilt 2a against which the first side 10a rests.
[0064] Similarly, the second flank 10b may have a substantially flat portion 20b situated between its curved portion 16b and the closed upper face 8. This substantially flat portion 20b is preferably parallel to the face 21b of the second stilt 2b (see [Fig. 17] to [Fig. 20]).
[0065] Each substantially flat part 20a, 20b can constitute a contact part bearing against a stilt 2a, 2b. Its flatness allows better positioning of the sealing box 1 against said stilt 2a, 2b and prevents any damage to the latter.
[0066] According to another variant of the invention illustrated in [Fig.13] to [Fig.16], the substantially flat part 20a of the first flank 10a and the substantially flat part 20b of the second flank 10b can be parallel to each other.
[0067] According to an example of the invention illustrated in [Fig.13] to [Fig.17], the sealing box 1 can be mounted so that only the first side 10a is in contact with the first stilt 2a, while the second side 10b is at a distance D from the second stilt 2b.
[0068] According to another example of the invention illustrated in [Fig. 18] to [Fig. 20], the box sealing 1 can be mounted so that both the first and second flanks 10a, 10b are in support against Péchasse 2a, 2b located opposite said flanks 10a, 10b.
[0069] The curved parts 16, 16a, 16b are obtained, for example, by bending the sheet metal of the sealing box 1 over a die. Other methods can also be considered, in particular by bending without a die, or by welding and then grinding.
[0070] Although in the figures the different edges 11, 12 appear sharp, they are preferentially rounded as a safety measure for the operators during assembly.
[0071] Although described through a number of examples, variants and embodiments, the sealing box and sealing assembly according to the invention include various variants, modifications and improvements which will be obvious to a person skilled in the art, it being understood that these variants, modifications and improvements are part of the scope of the invention.
Claims
Demands
1. Sealing assembly for two adjacent movable blades (3, 3a, 3b) within the same rotor stage of a turbojet engine, said turbojet engine extending longitudinally along an axis (X), the sealing assembly comprising: - a first foot (13, 13a) of a first movable blade (3, 3a), comprising a first platform (4, 4a) equipped with a first stilt (2, 2a) extending radially towards the axis (X); - a second foot (13, 13b) of a second movable blade (3, 3b) comprising a second platform (4, 4b) equipped with a second stilt (2, 2b) extending radially towards the axis (X), the second platform (4, 4b) being located opposite and in line with the first platform (4, 4a); and - a sealing box (1) located between the first and second feet (13, 13a, 13b) and having: • a closed upper face (8) in contact with a lower face (14, 14a, 14b) of at least one platform (4) among the first and second platforms (4a, 4b), • sides (10, 10a, 10b) extending the upper face (8) downwards and ending with a free edge (15) which delimits an opening (9) in the lower part of the sealing box (1), a first side (10, 10a) being in contact with the first stilt (2, 2a), and a second side (10, 10b) being located opposite the first side (10, 10a); and characterized in that - at the level of its free edge (15), the first side (10, 10a) has a curved part (16, 16a) towards the inside of the sealing box (1).
2.
3. A sealing assembly according to claim 1, characterized in that the first flank (10, 10a) has a substantially flat portion (20, 20a) situated between its curved portion (16, 16a) and the closed upper face (8). A sealing assembly according to claim 2, characterized in that the substantially flat portion (20, 20a) of the first flank (10, 10a) is parallel to a face (21a) of the first stilt (2, 2a) located opposite.
4. Sealing assembly according to any one of the preceding claims, characterized in that at its free edge (15), the second flank (10, 10b) also has a curved part (16, 16b) towards the inside of the sealing box (1).
5. Sealing assembly according to any one of the preceding claims, characterized in that at their free edge (15), all the flanks (10, 10a, 10b) have a curved part (16, 16a, 16b) towards the inside of the sealing box (1).
6. Sealing assembly according to any one of the preceding claims, characterized in that the second flank (10, 10b) has a substantially flat part (20, 20b) which is parallel to a face (21b) of the second stilt (2, 2b) located opposite.
7. Sealing assembly according to any one of the preceding claims, characterized in that an external face (17) of at least one curved part (16, 16a, 16b) is coated with a layer of elastomer (18).
8. Sealing assembly according to any one of the preceding claims, characterized in that an external face (17) of all the curved parts (16, 16a, 16b) is coated with a layer of elastomer (18).
9. Sealing assembly according to any one of claims 7 and 8, characterized in that an elastomer layer (18) has an average thickness of between 0.1 and 5 mm, preferably between 0.2 and 2 mm, more preferably between 0.3 and 1 mm.
10. Sealing assembly according to any one of the preceding claims, characterized in that the sealing box (1) has an average thickness of 0.5 ± 0.05 mm.