Sealing gasket for turbomachine

Abstract

This document presents an annular sealing gasket (10) comprising a plurality of gasket sectors (30, 60, 62) distributed circumferentially around a longitudinal axis (A), each gasket sector (30, 60, 62) comprising an inner ring sector (30) connected to an outer ring sector (60) by a return member (62), the sealing gasket (10) further comprising a sealing member (32, 34, 38, 40) comprising an annular row of blades (32) held axially against the inner (30) and outer (60) ring sectors by a retaining cup (40). (See Figure 4 in the abstract.)

Description

Title of the invention: Gasket for turbomachine Technical field

[0001] The present disclosure relates to the design of a seal for a turbomachine as well as a turbomachine comprising such a seal. Prior art

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0003] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation result in moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0004] In this context, engine efficiency is constantly being improved, which sometimes has an impact on the temperature of the gases or structural elements downstream of the combustion chamber. Controlling temperatures at the turbine level is essential for reasons of mechanical strength and control of expansion deformations.

[0005] Patent document FR 3 080 406 A1 describes a turbine distributor in which the blades are hollow and are adapted to receive a flow of air cooling the blades and taken from the compressor.

[0006] The cooling air for the turbines can be taken downstream of the compressor and radially below the combustion chambers. This air flow passes through three seals: a seal downstream of the high-pressure compressor, called "CDP" for "compressor discharge pressure" in English; an internal seal, called "FIS" for "forward inner seal" in English; and an external seal, called "FOS" for "forward outer seal" in English. These seals are generally labyrinth seals. Labyrinth seals are formed of licks arranged on the rotor which cooperate with an abradable of the stator. The abradable can have a honeycomb-type alveolar structure.

[0007] The disadvantage of this type of seal lies in the fact that the friction of the wipers on the abradable material tends to deteriorate the abradable material and consequently to increase the clearance between the rotor and the stator. This induces an increase in the air flow rate passing through the seals. Depending on the seal in question (CDP, FIS, FOS), this means an increase or a decrease in the air flow rate supplied to the turbines and therefore a deviation from a target, optimized air flow rate value. Thus, the increase in the clearance between these seals and the rotors can have two major consequences: a reduction in the efficiency of the turbomachine, and insufficient cooling of the turbines.

[0008] Therefore, there is a need to ensure consistency of flow rates through the seals over the entire life of the seals.

[0009] The present invention aims to propose a turbomachine seal which makes it possible to control the flow of cooling air supplied to the turbines, regardless of its service life.

[0010] To this end, the present document relates to an annular sealing joint comprising a plurality of seal sectors arranged circumferentially around a longitudinal axis, each seal sector comprising an inner ring sector connected to an outer ring sector by a return member, the sealing joint further comprising a sealing member comprising an annular row of blades held in axial support against the inner and outer ring sectors by a holding cup.

[0011] This design minimizes air leakage radially above the inner ring sector without impeding radial movement of the inner ring sector. Thus, control of the clearance between the seal and the rotor can be achieved by means of a simple and reliable design.

[0012] Such a seal architecture differs from a labyrinth seal. The inner ring sector is radially movable and has an internal interface with a rotor. The lift of the inner sector and the return member ensure that a predefined clearance is maintained with the inner rotor.

[0013] It is obvious that the sealing of the seal is not a strict seal in the sense that air could not pass through the seal, but a relative seal, the purpose of the seal being to allow a controlled quantity of air to pass, but only between the seal and the rotor. The sealing member takes care not to allow air to pass between the internal ring sector and the external ring sector.

[0014] It is understood that the predefined game is a “target” game, and that it is possible that the game varies slightly around the predefined clearance value under certain conditions of use of the seal. When the seal is in its equilibrium position, the predefined clearance ensures that the airflow through the seal is the desired airflow. However, if the clearance increases or decreases, the seal will be returned to the predefined clearance in relation to a spring behavior of the internal ring sectors ensured in particular by the return members and the airflow.

[0015] More specifically, if the clearance between the seal and the rotor becomes smaller than the predefined clearance, the friction of the air under the inner ring sector tends to move the inner ring sector so as to increase the clearance. Conversely, if the clearance between the seal and the rotor becomes larger than the predefined clearance, the return member exerts a force greater than the lift of the inner ring sector, the inner ring sectors then returning to their equilibrium positions, i.e. to the predefined clearance.

[0016] This mechanical-aerodynamic balance which regulates a predefined clearance also makes it possible to avoid any contact between the rotor and the seal, thus overcoming the wear problem encountered with conventional labyrinth seals.

[0017] The "circumferential distribution" of the seal sectors is intended to mean that each seal sector defines a portion of the circumference of the seal, and that the set of seal sectors makes it possible to obtain the complete seal. Optionally, the distribution is regular and each seal sector then represents an equal portion of the circumference of the sealing gasket.

[0018] The terms "internal" and "external", or indifferently "inside" and "outside", refer to a radial position relative to the central axis of the seal around which the seal sectors are arranged. "Upstream" and "downstream" are to be understood in the main direction of flow of the flow in a turbomachine.

[0019] According to one embodiment, in which the blades have openings aligned with blind holes formed in the outer ring sectors, the sealing member comprising pins provided with a head and a rod, each rod passing through one of the openings of the blades and being inserted into the corresponding blind hole, the holding cup holding the blades against the inner and outer ring sectors by means of the pins' heads.

[0020] Leaks via the pins are avoided by the fact that the holes are blind.

[0021] The pins are optional and the holding cup can be in direct contact with the blades.

[0022] In one variant, the holes are through holes.

[0023] According to one embodiment, the pins are mounted floating in the blind holes of the external ring sectors.

[0024] By "floating" is meant that the pins are not fixed to the blades or ring sectors. They are held in position by the upstream holding cup and the outer ring sector downstream.

[0025] In a variant, the pins are fixed to the external ring sector. The pins can be fixed to the ring sector by welding, threading or circlip in particular. The pins can thus apply an axial force on the blades even in the absence of the retaining cup, which has become optional.

[0026] According to one embodiment, each pin head has a spherical cap. The pin is therefore as light as possible and the contact between the holding cup and the pin is punctual, allowing, by design, good control of the pressure applied to the blades.

[0027] According to one embodiment, the retaining cup is fixed to an external radial flange for fixing the annular sealing gasket to a casing. Optionally, axial fixing elements pass through the retaining cup, the external radial flange and an internal radial flange of the casing. This configuration makes it possible in particular to share the screw elements and therefore to obtain a simple, reliable, lightweight and compact design. The axial fixing elements can be screws or bolts.

[0028] According to one embodiment, the holding cup is formed from a pin-folded sheet metal having two flat portions perpendicular to the longitudinal axis and a connecting portion describing a cylinder around the longitudinal axis; or in which the holding cup is formed from a plurality of pin-folded sheets each having two flat portions perpendicular to the longitudinal axis and a connecting portion describing a cylinder sector around the longitudinal axis.

[0029] Thus, the holding cup can extend over 360° around the axis or be sectorized, continuously or discontinuously (the sectors are circumferentially spaced). The cup sectors can cover one or more ring sectors, one or more pins (for example 2), and / or one or more blades.

[0030] According to one embodiment, blade covers at least partially cover two circumferentially adjacent blades. These blade covers ensure a seal between two adjacent blades.

[0031] According to one embodiment, the plurality of blades comprises a blade mounted axially opposite each joint sector. Thus, the plurality of blades consists of a respective blade for each joint sector.

[0032] According to one embodiment, each internal ring sector comprises an external lip with a front surface on which the axial support of the blades against the internal ring sectors is carried out.

[0033] In one embodiment, the seal comprises between 8 and 20 seal sectors.

[0034] This range of values ​​constitutes a good compromise between too few sectors, synonymous with heavy sectors for the return organs, and too many sectors, synonymous with numerous inter-sector gaps and therefore potential air leaks.

[0035] In one embodiment, the outer ring sectors of a seal may be a single piece, for example a ferrule. In other words, there is no physical separation between two circumferentially successive outer ring sectors.

[0036] In one embodiment, such a ferrule may be monolithic, i.e. made in a single piece without connection. In such a case, it will be considered that an angular portion of the ferrule can be considered as an external ring sector.

[0037] The invention also relates to a method for assembling an annular sealing joint according to one of the embodiments mentioned above, the method comprising the steps of: providing an assembly comprising a plurality of seal sectors distributed circumferentially around a longitudinal axis, each seal sector comprising an inner ring sector connected to an outer ring sector by a return member; positioning blades in axial support against the inner and outer ring sectors; then positioning a holding cup applying a force to the blades to maintain contact between the blades and the inner and outer ring sectors.

[0038] Optionally, the blade covers and the pins are also assembled to the assembly and the support provided by the holding cup is indirect on the blades.

[0039] The invention also relates to a turbomachine comprising: a high-pressure compressor; a combustion chamber; a high-pressure turbine; a first, a second and a third seal; and a circuit for conveying cooling air to the high-pressure turbine, the air conveying circuit comprising an air inlet downstream of the high-pressure compressor, a duct separated from the inlet by the first seal, a housing separated from the duct by the second seal, an air injector opening into the housing, a bleed outlet separated from the housing by the third seal and an air outlet from the housing directing the air flow to the high-pressure turbine, at least one of the first, second and third seals being in accordance with one of the embodiments set out above.

[0040] Depending on the position envisaged, the first seal is a seal downstream of the high-pressure compressor (called "CDP" for "compressor discharge pressure" in English), the second seal is a forward inner seal (called "FIS" for "forward inner seal" in English) and the third seal sealing is a forward outer seal (called “FOS” for “forward outer seal” in English).

[0041] It has been found that the seals of the invention allow better control of the clearance during their lifetime than labyrinth seals, and thus ensure maintenance of the performance of the turbomachine and efficient cooling of the turbines throughout the life of the seal. Brief description of the drawings

[0042] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0043] [Fig.l] is a schematic sectional view of a turbomachine;

[0044] [Fig.2] is a sectional view of a turbine cooling circuit;

[0045] [Fig.3] is a front view of a seal according to the invention;

[0046] [Fig.4] is a sectional view of a joint sector;

[0047] [Fig.5] is a partial view of the blade and blade cover assembly. Description of the embodiments

[0048] The figures describe different aspects of the invention in a schematic manner. The dimensions are not shown to scale: certain dimensions are enlarged to facilitate reading of the drawings and understanding of the phenomena involved. The term “approximately”, used to describe the dimensions of the various elements, is to be considered as synonymous with a tolerance of + / - 10%.

[0049] The axial direction is that of the longitudinal axis of the turbomachine, denoted A. The radial direction is perpendicular and coplanar to the direction A. The circumferential or tangential direction is orthogonal to the axial direction and to the radial direction.

[0050] The present invention preferably falls within the scope of aircraft turbo-machines. In this respect, [Fig.l] schematically represents, in section along a vertical plane passing through its longitudinal axis A, a double-flow turbojet 1. It comprises from upstream to downstream according to the circulation of the air flow, 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. It is understood that the invention is not limited to a turbomachine specifically with this structure.

[0051] The air entering the turbomachine is cold. It is compressed by compressors 3 and 4 and rises in temperature to approximately 500-600°C. At the outlet of combustion chamber 5, the air is at a temperature of around 1500 to 2000°C. Turbines 6 and 7 therefore see hot air and are therefore subject to deformation and thermal wear. One way of regulating the temperature of the turbines is to take less hot air, under combustion chamber 5 and at the level of the last stages of the compressor 4, and to route this air downstream to cool the turbines.

[0052] [Fig. 2] represents a portion of the turbomachine of [Fig. 1], and in particular the combustion chamber and seals.

[0053] In the embodiment shown, the turbomachine portion has three seals: a seal 10 downstream of the high pressure compressor (“CDP”), a front inner seal 12 (“FIS”), and a front outer seal 14 (“FOS”).

[0054] [Fig. 2] is only one example of a configuration for an air cooling path in a turbomachine, and the person skilled in the art will be able to identify the respective CDP, FIS and FOS seals in other cooling circuit geometries.

[0055] In the embodiment shown, an air inlet 9 makes it possible to take air 16 downstream of the last compressor disc. The air 16 taken downstream of the last compressor disc first passes through the seal 10, which is located radially below the inlet of the combustion chamber 5.

[0056] The air 16 continues its path in a conduit 11 which can be annular around the axis A.

[0057] The air then passes through a second seal (front internal seal) 12 and opens into a housing 13 arranged between the second seal 12 and a third seal (front external seal) 14.

[0058] Air is also taken from under the combustion chamber 5. Air injectors 15 coming from a cavity 17 under the combustion chamber open into the housing 13.

[0059] The air 16 coming from the compressor and that coming from the injectors 15 meet at the level of the housing 13. This air is then directed towards a cooling circuit 18 of the first stage of the turbine 6 via an outlet 19 of the housing 13. The seal 14 makes it possible to regulate an air outlet from the housing 13 towards a purge circuit 20, axially positioned between a distributor 6.1 and the first mobile turbine wheel 6.

[0060] The flow 18 is intended to cool the turbine and in particular to cool the hollow blades of the turbine 6.

[0061] The quantities of air regulated by the seals 10, 12, 14 are dictated by the clearance between these seals and a respective internal surface 22 facing the seals. In the embodiment shown, the surface 22 facing the seals 10, 12, 14 is an external surface of a rotor assembly.

[0062] In the following, the seal of the invention will be described with the number 10 but it should be noted that what is described for this seal can also, or alternatively, be applied to the other seals 12, 14.

[0063] [Fig.3] shows a part of a joint 10 in front view, perpendicular to direction A.

[0064] The seal 10 is composed of sectors which are distributed in a circumferential direction T around the axis A. Each sector accounts for an angular part of a ring describing 360° around the axis A. Each sector comprises an internal annular sector 30, an external annular sector 60, and a return member 62. The return member 62 is connected to the internal annular sector 30 at a base 64, and the return member 62 is connected to the external annular sector 60 at a base 66.

[0065] The seal 10 can be formed from 8 to 20 sectors.

[0066] The outer ring sectors 60 may together form a single ring. The sectorization is in this case purely geometric. Alternatively, the outer ring sectors 60 may be formed from separate pieces, assembled together.

[0067] The return member 62 may be formed of two blades of a thickness intended to give them a predetermined elasticity, for example between 0.7 and 2.0 mm. The total thickness of the return member may be between 2.5 and 5.0 mm. It is understood that another number of blades (1, 3, 4) or another elastic spring technology may be used.

[0068] The internal ring sectors 30 are spaced from each other by a distance e. This distance is exaggerated in [Fig. 3]. This distance may be less than 0.3 mm.

[0069] The assembly shown in [Fig. 3] may be a single piece, i.e. the internal ring sectors 30, the external ring sectors 60, the return members 62 and the bases 64, 66 may be formed from a single piece.

[0070] The inner ring sectors 30 are spaced from a rotor 22 by a clearance j. The seal 10 is designed to provide a predefined clearance j. The predefined clearance may be between 0.1 and 1.0 mm. This clearance corresponds to a target air flow rate for a given engine speed or load.

[0071] If, during operation of the turbomachine, the clearance j becomes too large, the return member 62 will tend to impart a force radially towards the axis A to reduce the clearance j. Conversely, if the clearance j becomes too small, the air flow passing at the interface between the internal ring sector 30 and the rotor 22 will increase in pressure and will tend to move the internal ring sector 30 away from the axis A.

[0072] In [Fig.3], blades which cover the space between the internal ring sectors and the external ring sectors are not shown.

[0073] [Fig.4] shows a sectional view of a sector of the seal 10 in a plane containing the axis A. The upstream is on the left and the downstream is on the right. The cold air under pressure is to the left of the seal 10. The seal 10 is positioned between a rotor 22 at the bottom, and a stator casing (at the top).

[0074] In particular, the internal ring sector 30 can be seen, which has an external surface 30.1 and an internal surface 30.2. The internal surface 30.2 is separated from the rotor 22 by the clearance j. The internal ring sector 30 may have an upstream portion 30.3 having a radial thickness less than a downstream portion 30.4. The upstream portion 30.3 may extend axially upstream of the external ring sector 60. The return member 62 may be carried exclusively by the downstream portion 30.4.

[0075] The inner ring sector 30 may have an outer lip 30.5 which may be carried by the downstream portion 30.4. An edge 30.51 of the outer lip 30.5 may form a high point of the inner ring sector 30. The outer lip 30.5 has a front surface 30.52.

[0076] To prevent the pressurized air upstream of the seal 10 from passing through the seal in an uncontrolled manner between the inner ring sector 30 and the outer ring sector 60, an annular row of blades 32 is pressed against the inner 30 and outer 60 ring sectors by a holding cup 40. A blade 32 is visible in section in [Fig.4].

[0077] The blades 32 bear on the front surface 30.52 of the internal ring sector 30. The contact between the blade 32 and the front surface 30.52 is characterized by an annular zone (seen from the front as in [Fig.3]) of radial height d. This radial height d may be small enough to limit the friction due to the radial displacement of the internal ring sector 30 but large enough to maintain a seal regardless of the radial position of the internal ring sector 30. Thus, d may be between 0.5 and 3 mm.

[0078] On the outer side, the outer ring sector 60 has a body 60.1 having a front surface 60.2 with an inner end edge 60.3. The contact between the blade 32 and the front surface 60.2 of the outer ring sector 60 is characterized by an annular zone of radial height D. The blade 32 can extend radially beyond the front surface 60.2 and thus be in contact over the entire front surface 60.2 with the outer ring sector 60. The radial height D can be at least 3 times greater than the radial height d.

[0079] Thus, the blade 32 radially overlaps the entirety of the return member 62 and radially partially overlaps the inner 30 and outer 60 ring sectors.

[0080] The blade 32 may have a thickness greater than 0.2 mm. It may extend radially over a height of approximately 15 mm + / - 10%.

[0081] The blades 32 form an annular row, that is to say a set sharing the same axial position and distributed circumferentially around the axis A (see also [Fig.5]).

[0082] Between each pair of blades 32 there is a small gap allowing the free movement of the internal ring sectors 30 under the influence of thermal expansion. The gap may have a circumferential width of less than 0.4 mm.

[0083] The blade 32 may be covered with a blade cover 34 which circumferentially overlaps two adjacent blades 32. In other words, seen radially, the blades 32 and blade covers 34 are arranged in a staggered pattern.

[0084] The blades 32 and blade covers 34 may have the same radial height of approximately 15 mm.

[0085] In order to support the blade 32 and the possible blade cover 34 against the ring sectors 30, 60, a possible pin 38 and a holding cup 40 are provided.

[0086] The pin 38 of the sealing member may comprise a head 38.1 and a rod 38.2. The head 38.1 may be in contact with a blade 32 or a blade cover 34. The rod 38.2 may extend parallel to the axis A. It may pass through the blade 32 and / or the blade cover 34 and / or the external ring sector 60. It may be inserted into a blind hole 60.4 of the external ring sector. Preferably, the rod 38.2 is mounted floating in the blind hole 60.4 of the external ring sector 60. The pin 38 is held fixed in axial translation by the holding cup 40 and the external ring sector 60. The cup 40 holds the blades 32 against the ring sectors 30, 60 by means of the heads 38.1 of the pins 38.

[0087] The diameter of the rod 38.2 may be approximately 1 mm and its length may be greater than 20 mm. The diameter of the head 38.1 may be greater than 5 mm. The head 38.1 of the pin may have a spherical cap to form a point contact with the holding cup 40.

[0088] The blade 32, the possible blade cover 34 and the external ring sector 60 can be pierced to allow the passage of the rod 38.2 of the pin 38.

[0089] Thus, the external ring sector 60 has a blind hole 60.4 parallel to the axis A and with a diameter slightly greater than the diameter of the rod 38.2 of the pin 38. For example, the diameter may be approximately 1.10 mm.

[0090] An outer radial flange 60.5 is provided for fixing the seal 10 to an inner radial flange 24.1 of the casing 24. The outer radial flange 60.5 may be integral with the outer ring sectors 60.

[0091] The holding cup 40 can be fixed to the flange 60.5. The holding cup 40 can be formed by a flat sheet folded into a hairpin and having two mutually parallel flat portions 40.1, 40.2. The flat portions 40.1, 40.2 can be perpendicular to the longitudinal axis A. One of the flat portions 40.1 can completely cover the head 38.1 of the pin 38: the internal radial end 40.4 of the holding cup can be at a radial position approximately median of the blades 32. The two flat portions 40.1, 40.2 are connected to each other by a connecting portion 40.3 which can describe a cylinder around the longitudinal axis A.

[0092] The retaining cup 40 can be fixed to the outer ring sector 60 via axial fixing elements 70. These can pass through the retaining cup 40, the radially outer flange 60.5 of the seal 10 and the flange 24.1 of the casing 24. The flat portion 40.2 of the cup is thus affixed and held against the flange 60.5. cup can have a sheet thickness of approximately 1 mm.

[0093] The retaining cup 40 is subjected to pressurized air on its left and presses on the pin 38 on its right. The retaining cup 40 incidentally makes it possible to reduce the viscous friction of the air on the screws 70 and on the pins 38.

[0094] The holding cup 40 may be formed from a single sheet or from several sectors of sheets 40 distributed circumferentially, joined or spaced from each other, each sector having two flat portions 40.1, 40.2 and a connecting portion 40.3 describing a cylinder sector.

[0095] The pin 38 can pass through openings provided in the blade 32 and the blade cover 34. [Fig. 5] shows two blades 32 among the annular row of blades 32 (which together describe 360° around the axis A). The joint 10 can comprise as many blades 32 as there are internal ring sectors 30. The blades 32 can respectively cover each internal ring sector 30. Alternatively, there are more blades 32 than sectors 30 and each ring sector 30 therefore sees two or three blades 32. Alternatively, one blade 32 can cover more than one internal ring sector 30.

[0096] A blade cover 34 is also shown, covering the gap between the two blades 32 (gap shown by a dotted line in [Fig.5]). The blade cover 34 covers at least two circumferentially adjacent blades 32. The blades 32 each have two openings 32.1 in a radially upper region close to the circumferential ends of the blades 32. The blade cover 34 has two openings 34.1 in a radially upper region close to the circumferential ends of the blade cover 34.

[0097] The openings of the blades 32 and the blade cover 34 coincide to allow the pin 38 to pass through these openings 32.1, 34.1.

[0098] In the mounted position, the openings 32.1, 34.1 are aligned with the blind hole 60.4 ([Fig.4]) of the outer ring sector 60.

[0099] The diameter of the openings 32.1, 34.1 may be equal to that of the orifice 60.4, that is to say be a little greater than the diameter of the rod 38.2 of the pin 38.

[0100] The circumferential width of the blade cover 34 may be smaller than the circumferential width of the blades 32, the ratio being between 0.2 and 0.5.

[0101] Also, a larger or smaller number of pins may be chosen to hold the blades.

[0102] With reference to Figures 4 and 5, the procedure for assembling the seal in the turbomachine can be carried out as follows: the entire internal ring sector 30, the external ring sector 60 and the return member 62, which can be a single piece, is provided; the blades 32 are put in place in contact with the front surfaces 30.52, 60.2; the possible blade cover 34 is arranged to cover the gap between two adjacent blades 32; the possible pin 38 is inserted into the orifice(s) provided for this purpose, then the holding cup is fixed to the external ring sector.

[0103] To do this, the assembly can be placed horizontally, that is to say with the axis A vertical.

[0104] The screw(s) 70 may be inserted into the retaining cup 40 before the assembly of the cup and screws is slid axially so as to cause the screw(s) 70 to penetrate into the flange 60.5. The assembly may then be slid axially against a fixing flange of the casing 24 to place a nut there (visible in [Fig.4])•

[0105] Although [Fig.4] shows a pin, this is optional and the cup can take a different shape (its end 40.4 can be inclined or stepped) to directly press on the blades 32 and / or counter-blades 34.

Claims

Claims

1. An annular seal (10, 12, 14) comprising a plurality of seal sectors (30, 60, 62) arranged circumferentially around a longitudinal axis (A), each seal sector (30, 60, 62) comprising an inner ring sector (30) connected to an outer ring sector (60) by a return member (62), the seal (10, 12, 14) further comprising a sealing member (32, 34, 38, 40) comprising an annular row of blades (32) held in axial abutment against the inner (30) and outer (60) ring sectors by a holding cup (40).

2. An annular sealing gasket (10, 12, 14) according to claim 1, wherein the blades (32) have openings (32.1) aligned with blind holes (60.4) formed in the outer ring sectors (60), the sealing member (32, 34, 38, 40) comprising pins (38) provided with a head (38.1) and a rod (38.2), each rod (38.2) passing through one of the openings (32.1) of the blades and being inserted into the corresponding blind hole (60.4), the holding cup (40) holding the blades (32) against the inner (30) and outer (60) ring sectors by means of the heads (38.1) of the pins (38).

3. An annular sealing joint (10, 12, 14) according to claim 2, in which the pins (38) are mounted floating in the blind holes (60.4) of the outer ring sectors (60).

4. Annular sealing joint (10, 12, 14) according to one of claims 2 or 3, in which each head (38.1) of pin (38) has a spherical cap.

5. A sealing ring (10, 12, 14) according to one of the preceding claims, wherein the retaining cup (40) is fixed to a radially outer flange (60.5) of the sealing ring (10) to a housing (24).

6. An annular seal (10, 12, 14) according to the preceding claim, wherein axial fixing elements (70) pass through the retaining cup (40), the radially outer flange (60.5) of the annular seal (10) and a radially inner flange (24.1) of the casing (24).

7. An annular sealing gasket (10, 12, 14) according to one of the preceding claims, in which the retaining cup (40) is formed from a pin-folded sheet metal having two flat portions (40.1, 40.2) per- pendicular to the longitudinal axis (A) and a connecting portion (40.3) describing a cylinder around the longitudinal axis (A); or in which the holding cup (40) is formed from a plurality of hairpin-folded sheets each having two flat portions (40.1, 40.2) perpendicular to the longitudinal axis (A) and a connecting portion (40.3) describing a cylinder sector around the longitudinal axis (A).

8. An annular sealing gasket (10, 12, 14) according to one of the preceding claims, in which blade covers (34) at least partially cover two circumferentially adjacent blades (32).

9. An annular sealing joint (10, 12, 14) according to one of the preceding claims, in which the plurality of blades (32) comprises a blade (32) mounted axially opposite each seal sector (32, 60, 62).

10. An annular sealing gasket (10, 12, 14) according to one of the preceding claims, in which each internal ring sector (30) comprises an external lip (30.5) with a front surface (30.52) on which the axial support of the blades (32) against the internal ring sectors (30) takes place.

11. A method of assembling an annular sealing gasket (10, 12, 14) according to one of the preceding claims, comprising the steps of: providing an assembly comprising a plurality of gasket sectors (30, 60, 62) distributed circumferentially around a longitudinal axis (A), each gasket sector (30, 60, 62) comprising an inner ring sector (30) connected to an outer ring sector (60) by a return member (62); positioning blades (32) in axial support against the inner (30) and outer (60) ring sectors; then positioning a holding cup (40) applying a force to the blades (32) to maintain contact between the blades (32) and the inner (30) and outer (60) ring sectors.

12. A turbomachine (1) comprising: a high-pressure compressor (4); a combustion chamber (5); a high-pressure turbine (6); a first, a second and a third seal (10, 12, 14); and a circuit (9-20) for conveying cooling air to the high-pressure turbine (6), the air conveying circuit comprising an air inlet (9) downstream of the high-pressure compressor (4), a duct (11) separated from the inlet (9) by the first seal (10), a housing (13) separated from the duct (11) by the second seal (12), an air injector (15) opening into the housing (13), a purge outlet (20) separated from the housing (13) by the third seal (14) and an air outlet (19) from the housing (13) directing the air flow (18) towards the high pressure turbine (6), at least one of the first, second and third seals (10, 12, 14) being in accordance with any one of claims 1 to 10.

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