Seal for a turbine engine

Abstract

The present application relates to an annular seal (10) comprising a plurality of seal sectors (30, 60, 62) distributed circumferentially about a longitudinal axis (A), each seal sector (30, 60, 62) comprising an inner ring sector (30) that is connected to an outer ring sector (60) by a return member (62), the seal (10) further comprising a sealing member (32, 34, 36, 38, 40) having an annular row of blades (32) that axially bear against the inner (30) and outer (60) ring sectors by elastic retaining means (36).

Description

Description Title: 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. Various states have, are, or will adopt various carbon emission restrictions. In particular, an ambitious standard applies to both new aircraft types and those already in operation, requiring the implementation of technological solutions to comply with current regulations. For several years now, civil aviation has been mobilizing to contribute to the fight against climate change.

[0003] Technological research efforts have already led to significant improvements in 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] Turbine cooling air can be taken downstream of the compressor and radially below the combustion chambers. This airflow 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 by lips arranged on the rotor which cooperate with an abradable material of the stator. The abradable material can have a honeycomb-type alveolar structure.

[0007] The disadvantage of this type of seal is that the friction of the wipers on the abradable material tends to damage the abradable material and consequently increase the clearance between rotor and stator. This leads to an increase in the airflow through the seals. Depending on the seal in question (CDP, FIS, FOS), this means an increase or decrease in the airflow supplied to the turbines and therefore a deviation from an optimized target airflow value. Thus, the increase in 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. Summary

[0009] The present invention aims to provide 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 distributed circumferentially around a longitudinal axis, each seal sector comprising an internal ring sector connected to an external 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 internal and external ring sectors by elastic holding means.

[0011] This design minimizes air leakage radially above the inner ring sector without hindering the radial movement of the inner ring sector. Thus, the clearance control between the seal and the rotor can be controlled.

[0012] This 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 with the internal rotor is maintained.

[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 ensures that no air passes between the inner ring sector and the outer ring sector.

[0014] It is understood that the predefined clearance is a “target” clearance, and that it is possible for the clearance to vary 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 with respect 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 understood to mean that each seal sector defines a portion of the seal circumference, and that the set of seal sectors together makes up the complete seal. Optionally, the distribution is regular and each seal sector then represents an equal portion of the seal circumference.

[0018] The terms "internal" and "external", or interchangeably "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, each blade has two aligned openings with orifices passing through the outer ring sectors; and a plurality of pins is inserted into the openings and the orifices, each pin having a head putting one of the elastic holding means into axial compression and a rod opening downstream of the outer ring sector.

[0020] It is thus possible to control the force applied to the blades by choosing pins of the appropriate size. During maintenance operations, the pins can be replaced, if necessary, with shorter pins, to maintain the same bearing force on the blades and continually control the clearance regardless of the age of the seal.

[0021] The pins can be fixed in translation relative to the outer ring sector. For example, the pin rod can be welded to the outer ring sector, or its travel can be limited by a circlip.

[0022] According to one embodiment, a cup, fixed to a flange for fixing the seal to a casing, covers the head of at least two pins which compress the same elastic holding means.

[0023] The cup provides safety in the event of deformation of the elastic retaining means or the pin.

[0024] The cup can be formed from a single sheet, covering all of the pins, or from several sheets, distributed circumferentially to cover one or more pairs of pins.

[0025] According to one embodiment, the elastic holding means are pin-bent holding sheets. The holding sheets may be made of spring steel. Alternatively, other elastic means (e.g., helical springs) may be provided.

[0026] According to one embodiment, each holding means has two holes and two circumferentially adjacent notches, the pins passing through the holes on the one hand and the notches on the other hand to hold the elastic holding means in position. These material clearances limit the deterioration of the elasticity of the sheet metal over time, thus continuously controlling the clearance at the seal-rotor interface.

[0027] According to one embodiment, blade covers at least partially cover two circumferentially adjacent blades. These blade covers ensure a seal between two adjacent blades.

[0028] According to one embodiment, the support zone of the elastic holding means on the blades is positioned at a median distance between an inner radial end edge of the outer ring sector and an outer radial end edge of the inner ring sector. Thus, the elastic holding means can apply a lower force while ensuring sealing on both the inner ring sector and the outer ring sector. A lower force means a low deviation of the initial force during the life of the seal and therefore good control of the clearance over time. When blade covers are provided, the support zone can be a direct support zone of the elastic holding means on the blade cover and the force is only applied indirectly to the blades, via the blade covers.

[0029] According to one embodiment, the plurality of blades consists of a respective blade for each joint sector.

[0030] In one embodiment, the seal comprises between 8 and 20 seal sectors.

[0031] This range of values ​​represents a good compromise between too few sectors, which means heavy sectors for the recall devices, and too many sectors, which means many inter-sector gaps and therefore potential air leaks.

[0032] 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.

[0033] 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.

[0034] The invention also relates to a method of assembling an annular sealing gasket according to one of the embodiments discussed 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 elastic holding means applying a force to the blades to maintain contact between the blades and the inner and outer ring sectors. Optionally, the blade covers, the pins and the sheet(s) are also assembled to the assembly.

[0035] 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.

[0036] Depending on the position considered, 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 is a forward outer seal (called "FOS" for "forward outer seal" in English).

[0037] It has been found that the seals of the invention allow better control of the clearance during their service life 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

[0038] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which:

[0039] [Fig. 1] is a schematic sectional view of a turbomachine;

[0040] [Fig. 2] is a sectional view of a turbine cooling circuit;

[0041] [Fig. 3] is a front view of a seal according to the invention;

[0042] [Fig. 4] is a sectional view of a joint sector;

[0043] [Fig. 5] is a partial view of the blade and blade cover assembly;

[0044] [Fig. 6] is a detailed view of a retaining sheet;

[0045] [Fig. 7] is a partial isometric view of a gasket. Description of the embodiments

[0046] The figures depict various aspects of the invention schematically. The dimensions are not shown to scale: some dimensions are enlarged for ease of reading. drawings and understanding of the phenomena involved. The term "approximately", used to describe the dimensions of the different elements, should be considered synonymous with a tolerance of + / - 10%.

[0047] The axial direction is that of the longitudinal axis of the turbomachine, noted A. The radial direction is perpendicular and coplanar to direction A. The circumferential or tangential direction is orthogonal to the axial direction and to the radial direction.

[0048] The present invention preferably falls within the scope of aircraft turbomachines. In this respect, Figure 1 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.

[0049] The air entering the turbomachine is cold. It is compressed by compressors 3 and 4 and rises in temperature to around 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 very hot air and are therefore subject to deformation and thermal wear. One way to regulate the temperature of the turbines is to take cooler air, below combustion chamber 5 and at the level of the last stages of compressor 4, and to route this air downstream to cool the turbines.

[0050] Figure 2 represents a portion of the turbomachine of Figure 1, and in particular the combustion chamber and seals.

[0051] 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”).

[0052] Figure 2 is only one example configuration for an air cooling path in a turbomachine, and the skilled person will be able to identify the respective CDP, FIS and FOS seals in other cooling circuit geometries.

[0053] 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.

[0054] The air 16 continues its path in a conduit 11 which can be annular around the axis A.

[0055] 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.

[0056] Air is also taken from under the combustion chamber 5. Air injectors 15 from a cavity 17 under the combustion chamber open into the housing 13.

[0057] The air 16 coming from the compressor and that coming from the injectors 15 meet at 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 turbine wheel 6.

[0058] Flow 18 is intended to cool the turbine and in particular to cool the hollow blades of turbine 6.

[0059] 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.

[0060] 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.

[0061] Figure 3 shows a portion of a joint 10 in front view, perpendicular to direction A.

[0062] The joint 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.

[0063] The joint 10 can be formed from 8 to 20 sectors.

[0064] The outer annular sectors 60 may together form a single ring. The sectorization is in this case purely geometric. Alternatively, the outer annular sectors 60 may be formed from separate pieces, assembled together.

[0065] 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.

[0066] The internal annular sectors 30 are spaced from each other by a distance e. This distance is exaggerated in Figure 3. This distance may be less than 0.3 mm.

[0067] The assembly shown in Figure 3 may be a single piece, that is to say that 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.

[0068] The internal annular 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 can be between 0.1 and 1.0 mm. This clearance corresponds to a target air flow rate for a given engine speed or load.

[0069] If, during operation of the turbomachine, the clearance j becomes too large, the return member 62 will tend to apply 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.

[0070] In Figure 3, blades that cover the space between the inner ring sectors and the outer ring sectors are not shown.

[0071] Figure 4 shows a sectional view of a sector of the seal 10 in a plane containing the axis A. Upstream is on the left and 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 housing (at the top).

[0072] In particular, the inner ring sector 30 can be seen, which has an outer surface 30.1 and an inner surface 30.2. The inner surface 30.2 is separated from the rotor 22 by the clearance j. The inner 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 outer ring sector 60. The return member 62 may be carried exclusively by the downstream portion 30.4.

[0073] 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.

[0074] 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 placed in abutment against the inner 30 and outer 60 ring sectors. A blade 32 is visible in section in FIG. 4.

[0075] The blades 32 bear against 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 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.

[0076] 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.

[0077] 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.

[0078] The blade 32 may have a thickness greater than 0.2 mm. It may extend radially to a height of approximately 15 mm + / - 10%.

[0079] 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 figure 5).

[0080] Between each pair of blades 32 there is a small gap allowing the free movement of the inner ring sectors 30 under the influence of thermal expansion. The gap may have a circumferential width of less than 0.4 mm.

[0081] The blade 32 may be covered with a blade cover 34 (see also FIG. 5) which circumferentially overlaps two circumferentially adjacent blades 32. Thus, a blade cover 34 may at least partially cover two circumferentially adjacent blades 32. According to one embodiment, viewed radially, the blades 32 and blade covers 34 are arranged in a staggered manner.

[0082] The blades 32 and blade covers 34 may have the same radial height of approximately 15 mm.

[0083] In order to press the blade 32 and the possible blade cover 34 against the ring sectors 30, 60, elastic holding means apply an axial force. The elastic holding means can take different forms or use different technologies, such as for example Belleville washers, helical springs, elastomeric stops, etc. Figure 4 illustrates an advantageous embodiment of the elastic holding means in which the force applied to the blade 32 is obtained by a holding sheet 36, which can consist essentially of a spring steel plate folded back on itself. The holding sheet 36 is described in more detail in relation to Figure 6. It comprises in particular a flat portion 36.1, a bearing portion 36.2 on the blade 32 and / or the blade cover 34 and an angled portion 36.3 connecting the flat portion 36.1 to the bearing portion 36.2.

[0084] A pin 38 can hold the retaining plate 36 in a prestressed configuration. The pin 38 can comprise a head 38.1 and a rod 38.2. The head 38.1 can be in contact with the flat portion 36.1 of the retaining plate 36. The rod 38.2 can extend parallel to the axis A. It can pass through the blade 32 and / or the blade cover 34 and / or the outer ring sector 60. In particular, openings (32.1, 34.1 in FIG. 5) of the blade and the blade cover 34 can be aligned with an orifice 60.4 of the outer ring sector 60. The downstream end 38.3 of the rod 38.2 opens downstream of the outer ring sector 60 and can be fixed there, for example by a weld point, or be stopped in translation by a circlip. The pin 38 is thus fixed in axial translation with the external ring sector 60. The length of the pin 38, or more precisely the clearance between the head 38.1 and the blade 32 or the blade cover 34, dictates the prestressed state of the retaining sheet 36 and consequently the axial force exerted to keep the blade 32 in contact with the inner and outer ring sectors 30, 60 in order to guarantee sealing. The force applied by the retaining sheet 36 (directly or indirectly) on the blade 32 can be purely axial.

[0085] The diameter of the rod 38.2 may be about 1 mm and its length may be greater than 25 mm. It may extend projecting downstream of the outer ring sector 60 by about 2 to 5 mm once mounted in the latter. The diameter of the head 38.1 may be greater than 7 mm. The shape of the head 38.1 of the pin is here represented as a cylinder.

[0086] The support zone C between the holding plate 36 and the blade 32 or the blade cover 34 may be approximately equidistant (within + / -10%) from the internal edge 60.3 of the external ring sector 60 and from the external edge 30.51 of the internal ring sector 30. Thus, the support zone C of the elastic means 36 on the blades 32 is positioned at a median distance between the internal radial end edge 60.3 of the external ring sector 60 and the external radial end edge 30.51 of the internal ring sector 30.

[0087] 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.

[0088] Thus, the outer ring sector 60 has an orifice 60.4 which axially passes through the body 60.1 of the outer ring sector 60. This orifice 60.4 is parallel to the axis A and has 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.

[0089] An outer radial flange 60.5 is provided for fixing the seal 10 to a radially inner flange of a casing 24. The outer radial flange 60.5 may be integral with the outer ring sectors 60. A cup 40 may be fixed to the flange 60.5. This cup 40 may be formed by a folded flat sheet metal having two mutually parallel flat portions 40.1, 40.2. One of the flat portions 40.1 may completely cover the head 38.1 of the pin 38 and may partially cover the elastic holding means 36. The cup 40 may be fixed to the outer ring sector 60 via screws 70 which may be the screws 70 used to fix the seal 10 to the casing 24. The flat portion 40.2 of the cup is thus affixed and held against the flange 60.5. In one embodiment, the cup 40, fixed to the flange 60.5, covers the head 38.1 with at least two pins 38 which compress the same elastic holding means 36.The cup can have a sheet thickness of approximately 1 mm.

[0090] The cup 40 prevents any unexpected movement of the pin 38 in the event of breakage of the attachment (weld or circlip) of the rod 38.2 to the external ring sector 60. The cup 40 also makes it possible to reduce the viscous friction of the air on the screws 70 and on the pins 38. A clearance of less than one millimeter can be provided between the cup 40 and the head 38.1 of the pin 38. The cup 40 can be formed from a single sheet or from several sheets 40 distributed circumferentially, joined together or spaced apart from each other.

[0091] The pin 38 can pass through openings 32.1, 34.1 provided in the blade 32 and the blade cover 34. Figure 5 shows two blades 32 among the annular row of blades 32 (which together describe 360° around the axis A). The dotted line materializes the junction between the two blades 32, a junction which is hidden by the blade cover 34. The joint 10 can comprise as many blades 32 as of inner ring sectors 30. The blades 32 may respectively cover each inner 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, a blade 32 may cover more than one inner ring sector 30.

[0092] A blade cover 34 is also shown, covering the gap between the two blades 32. The blades 32 each have two openings 32.1 in a radially upper region and close to the circumferential ends of the blades 32. The blade cover 34 has two openings 34.1 in a radially upper region and close to the circumferential ends of the blade cover 34.

[0093] 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.

[0094] In the mounted position, the openings 32.1, 34.1 are aligned with the orifice 60.4 (fig. 4) of the outer ring sector 60.

[0095] 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.

[0096] Figure 6 shows two isometric views of the retaining plate 36. The retaining plate 36 may be formed by bending a spring steel sheet having a thickness that may be greater than 0.5 mm.

[0097] As mentioned previously, the holding plate 36 comprises a substantially planar portion 36.1 and a support portion 36.2 connected to the planar portion 36.1 by a curved portion 36.3. The support portion 36.2 may be formed of two circular portions of opposite concavity 36.21, 36.23. The support point 36.22 against the blade 32 or the blade cover 34 being arranged on the portion which, seen from downstream, is convex.

[0098] The holding plate 36 also comprises two holes 36.4 intended for the passage of the rod 38.2 of the pin. Circumferentially adjacent notches 36.5 make it possible to lighten the holding plate 36 and to adjust the elasticity to obtain a desired axial force on the blades 32. The pins pass through the holes 36.4 on the one hand and the notches 36.5 on the other hand, to hold the holding plate 36 in position.

[0099] The order of magnitude of the dimensions of the holding plate 36 may be as follows (according to all possible combinations of the following elements): the diameter of the holes 36.4 may be greater than the diameter of the rod 38.2 of the pin 38; the radius of curvature of the curved portion 36.3 may be less than 1 mm; the radial height of the support portion 36.2 may be greater than 15 mm. the radius of curvature of the portion 36.21 may be approximately 12 mm; the radius of curvature of the portion 36.23 may be approximately 5 mm; the total length of the plate used to form the holding plate 36, i.e. the curvilinear length on the right-hand part of FIG. 6, cumulative of the portions 36.1, 36.2 and 36.3 may be greater than 25 mm; the circumferential width (along the direction T on the left part of figure 6) can be greater than 25 mm and can optionally be identical to the circumferential width of the blade cover 34; the width circumferential of the notches 36.5 may be greater than 4 mm and / or these may be spaced from each other by at least 5 mm and / or these may be spaced at least 2 mm from the circumferential end edges; the holes 36.4 may be spaced from the lower upstream edge by at least 4 mm; the material thickness between the holes 36.4 and the notches 36.5 may be at least 2 mm; the curvilinear length of the notches (on the portions 36.1, 36.2 and 36.3) may be greater than 10 mm.

[0100] Figure 7 is a partial isometric view of the seal 10, without the cup 40. In particular, two adjacent blades 32 are seen, a blade cover 34 which partially covers the two blades 32 and which fills the space left by the gap between the two blades 32. A retaining plate 36 is applied against the blade cover 34 by means of two pins whose heads 38.1 are seen. The pins pass through respective openings and orifices of the retaining plate 36, the blade cover 34, the blades 32 and the external ring sector 60.

[0101] It is understood that in the example of figure 7, a blade 32 is affixed to each internal ring sector, and that the holding sheet 36 has a circumferential width close to that of the blade cover 34 but other configurations are possible with other relative dimensions.

[0102] 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.

[0103] Also, a greater or smaller number of pins may be chosen to maintain the retaining plate 36 in a prestressed state.

[0104] With reference to Figures 4 to 7, the method of assembling the seal in the turbomachine can take place as follows: the entire inner ring sector 30, the outer 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 circumferentially adjacent blades 32; the holding sheet 36 is put in place and the pins 38 are inserted into the orifices provided for this purpose, then the downstream end of the rod of the pins are fixed to the outer ring sector.

[0105] To do this, the assembly can be placed horizontally, i.e. with the axis A vertical. Shims can be used to finely adjust the clearance of the retaining plates before securing the pins 38 to the external ring sector 60.

[0106] The screw(s) 70 can be inserted into the cup 40 and then the assembly of the cup and screws can be slid axially so as to make the screw(s) 70 penetrate into the flange 60.5. The assembly can then be slid axially against a fixing flange of the casing 24 to place a nut there (visible in figure 4).

Claims

Claims

1. An annular sealing joint (10, 12, 14) comprising a plurality of seal sectors (30, 60, 62) distributed 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 sealing joint (10, 12, 14) further comprising a sealing member (32, 34, 36, 38, 40) comprising an annular row of blades (32) held in axial abutment against the inner (30) and outer (60) ring sectors by elastic holding means (36), each blade (32) having two openings (32.1) aligned with orifices (60.4) passing through the outer ring sectors (60) ; and a plurality of pins (38) is inserted into the openings (32.1) and the orifices (60.4), each pin (38) having a head (38.1) axially compressing one of the elastic holding means (36) and a rod (38.2) opening downstream of the external ring sector (60).

2. Annular sealing joint (10, 12, 14) according to claim 1, in which a cup (40), fixed to a flange (60.5) for fixing the joint (10, 12, 14) to a casing (24), covers the head (38.1) with at least two pins (38) which compress the same elastic holding means (36).

3. Annular sealing gasket (10, 12, 14) according to one of the preceding claims, in which the elastic holding means (36) are holding sheets folded into a pin.

4. Annular sealing joint (10, 12, 14) according to the preceding claim, in which each holding means (36) has two holes (36.4) and two circumferentially adjacent notches (36.5), the pins (38) passing through the holes (36.4) on the one hand and the notches (36.5) on the other hand to hold the elastic holding means (36) in position.

5. 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).

6. Annular sealing joint (10, 12, 14) according to one of the preceding claims, in which the support zone (C) of the elastic holding means (36) on the blades (32) is positioned at a median distance between an inner radial end edge (60.3) of the outer ring sector (60) and an outer radial end edge (30.51) of the inner ring sector (30).

7. An annular sealing gasket (10, 12, 14) according to one of the preceding claims, wherein the plurality of blades (32) consists of a blade (32) respective to each seal sector (32, 60, 62).

8. A method of assembling an annular seal (10, 12, 14) according to one of the preceding claims, comprising the steps of: providing an assembly comprising a plurality of seal sectors (30, 60, 62) distributed 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); positioning blades in axial support against the inner and outer ring sectors, each blade (32) having two openings (32.1) aligned with orifices (60.4) passing through the outer ring sectors (60); then positioning elastic holding means (36) applying a force to the blades to maintain contact between the blades and the inner and outer ring sectors by inserting a plurality of pins (38) into the openings (32.1) and the orifices (60.4), each pin (38) having a head (38.1) putting one of the elastic holding means (36) into axial compression and a rod (38.2) opening downstream of the outer ring sector (60).

9. 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) to 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 7.

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