Device for damping the bladed assembly of an aircraft turbomachine

Abstract

Device for damping a bladed assembly of an aircraft turbomachine Bladed assembly (1) of an aircraft turbomachine comprising a first and a blade (10, 20) extending between a blade root (11, 21) and a heel (12, 22), the heel (12, 22) of the blades (10, 20) respectively comprising a first and a second platform (121, 221), the heel (12) of the first blade (10) comprising a first covering wall (31) extending from the first platform (121) towards the second blade (20) so as to at least partially cover the second platform (221) while being radially spaced therefrom, the heel (22) of the second blade (20) comprising a first damping pin (41) arranged in a first guide orifice (51) of the second platform (221), the first pin (41) damping capable of moving in the first orifice (51) along a main direction (P),a displacement of the first pin (41) in the main direction (P) being limited by the first covering wall (31). Figure for the abstract: Fig. 2.,

Description

Title of the invention: Device for damping the bladed assembly of an aircraft turbomachine Technical field

[0001] The present disclosure relates to the general field of blades of modules of an aeronautical turbomachine such as an aircraft turbojet or turboprop. It aims more specifically at damping the vibration modes to which these blades are subjected during operation. The invention relates in particular to a bladed assembly for an aircraft turbomachine module, and a module, such as a compressor or a turbine, comprising such an assembly. Prior art

[0002] When turbomachine engines are in operation, the blades that comprise these turbomachines, in particular the moving compressor and turbine blades, but not only, are subjected to vibratory stresses that must be taken into account to ensure the good mechanical strength of these blades, and to increase the service life of the engine.

[0003] A known solution for limiting vibrational stresses on low-pressure turbine blades, for example, is the introduction of a frictional contact technology between the heels of circumferentially adjacent blades, this contact providing damping to the system. To do this, a specific cut of the lateral faces of the heel is carried out, by creating a protrusion on the extrados side, and a recess on the intrados side in a symmetrical manner. During assembly, contact is generated on these patterns by means of an angular deformation of the blade, or "pretorsion". When the engine is in operation, the vibrations of the blades cause relative sliding at the contact zones between these shapes. These relative slidings and the contact pressures induce friction damping.

[0004] However, this solution can prove complex to implement, during the manufacture of the blades and during assembly, and not very adaptable. Furthermore, during operation, the contact forces between the heels of the circumferentially adjacent blades can change compared to the initial forces during assembly, due to the natural rotation of the blades (clockwise or counterclockwise) or by the relative movements of the circumferentially adjacent heels (approaching or separating). To overcome the cases in which the contact pressures decrease during operation, it is necessary to amplify these contact pressures during assembly in order to maintain sufficient contact pressures during operation, and therefore sufficient damping.

[0005] However, this adaptation results in static over-stresses, which can prove problematic in certain cases. In particular, blades made of ceramic materials or ceramic matrix composite (CMC) are mechanically not very tolerant to pre-torsion. However, on this type of blade, strong pre-torsion during assembly induces strong static stresses compared to what these blades are able to withstand mechanically, which can be detrimental to their mechanical strength and their service life. In addition, ceramic or CMC blades expand less than metal blades. Consequently, in hot operation, the expansion of the heels, the contact pressures between them, and therefore the damping effects, are less than for metal blades.

[0006] There is therefore a need for a device making it possible to at least partially overcome the aforementioned drawbacks, and capable of effectively ensuring damping of vibration phenomena regardless of the material used for the blades. Statement of the invention

[0007] The present disclosure relates to a bladed assembly of an aircraft turbomachine centered on a central axis, the bladed assembly comprising a first blade and a second blade circumferentially adjacent, each extending in a radial direction relative to the central axis, between a blade root at a root end, and a heel at a tip end radially opposite the root end, the heel of the first blade comprising a first platform and the heel of the second blade comprising a second platform, the heel of the first blade comprising a first covering wall extending from the first platform towards the second blade so as to at least partially cover the second platform while being radially spaced therefrom, the heel of the second blade comprising a first damping pin disposed in a first guide orifice of the second platform,the first damping pin being able to move in the first orifice along a main direction of said first orifice, a movement of the first pin in the main direction being limited by the first covering wall.

[0008] In the present disclosure, the terms “axial”, “radial”, “circumferential”, “internal”, “external” and their derivatives are defined in relation to the main central axis of the turbomachine; furthermore, the terms “upstream” and “downstream” are defined in relation to the circulation of air in the turbomachine.

[0009] It is understood that the first blade and the second blade are adjacent to each other in the circumferential direction relative to the central axis, when the blades and the bladed assembly are arranged in a turbomachine module. Thus, the respective heels of the first blade and the second blade are also circumferential. ferentially adjacent to each other.

[0010] In a known manner, the heel of each blade fulfills both an aerodynamic function, via the platform (here, the first and second platforms) in contact with the internal flow of gas in the air circulation vein, and a sealing function in the case of moving blades, in particular via wipers carried by the platforms.

[0011] It is understood that the first covering wall is a portion of the heel of the first blade projecting circumferentially so as to overlap the second platform circumferentially adjacent to the first platform. The first covering wall typically forms a tongue extending from the first platform towards the second platform while being curved so as to be radially spaced from said second platform which it covers.

[0012] Furthermore, the first damping pin is arranged in the first guide orifice, formed through the second platform, in a floating manner. In other words, the pin can move by sliding inside the first orifice upwards and downwards, that is to say along the main direction of the first orifice, which is for example the central axis of the cylinder formed by the orifice when the latter is of cylindrical shape. However, the movement of the first pin in a direction of extraction from the first orifice, that is to say radially outwards along the main direction, is limited by the first covering wall which at least partially covers the second platform. It is thus understood that the first covering wall serves as a stop limiting the travel of the first pin in the main direction. In particular, the first covering wall prevents the extraction of the pin from the first orifice towards the outside.

[0013] Given this arrangement, the first damping pin can be brought into contact with the first covering wall, either by positioning it and thus locking it initially, that is to say cold during assembly, in the case of a fixed blade, or by the play of centrifugal forces in the case of moving blades. Indeed, in the latter case, when the moving blades are rotating, the first damping pin mounted floating in the first orifice naturally moves radially outwards, until it comes into contact with the first covering wall. The contact area between the first blade and the second blade thus created generates vibration damping. In particular, the radial contact force between the damping pin and the covering wall, and consequently the damping, are determined by the centrifugal acceleration and therefore by the engine speed.

[0014] The invention thus makes it possible to ensure, whatever the material used for the blade (metallic, ceramic or CMC), damping of the vibratory phenomena in upper part of a heel blade, by friction directly at the level of said heel, without the need to pre-stress the blade and by simple means to implement. In particular, the covering wall and the damping pin are compact, lightweight parts requiring simple machining. This invention also has the advantage of being modular. Indeed, the number of damping pins and their position can be chosen according to the vibration modes and the damping requirement, the contact points thus being known and predetermined. Furthermore, extra thicknesses can be easily installed at the level of the functional surfaces, in particular the damping pin and the covering wall, in order to cope with wear.

[0015] In certain embodiments, the first orifice is a through orifice, and the first damping pin comprises a main portion which extends longitudinally and which is housed in the first orifice, and a head arranged between a radially external face of the second platform and the first covering wall, the head having a section, taken in a plane of section transverse to the main portion, wider than a section of the first orifice, taken in the plane of section transverse to the main portion, so as to prevent withdrawal of the first damping pin radially inwards through the first orifice.

[0016] By through, it is understood that the first orifice opens onto both the radially internal face and the radially external face of the second platform. The main portion may be cylindrical with a circular section, without this shape being limiting, the main portion being able to alternatively have a rectangular section, or another shape. The head constitutes a simple shape to machine, making it possible to prevent the damping pin from being removed from the first orifice, in particular under the effect of gravity when the engine is stopped.

[0017] In certain embodiments, the first orifice of the second platform does not open onto a radially internal face of the second platform, the first damping pin comprising only a main portion housed in the first orifice.

[0018] According to this embodiment, the first orifice opens only onto the radially external face of the second platform, the first orifice being blocked on the internal side. The damping pin can thus no longer be extracted radially inwards, the presence of a head is no longer necessary. Consequently, the damping pin is formed solely by a main portion, of constant section (for example cylindrical) over the entire height of the pin. This solution makes it possible to further simplify the manufacture of the damping pin.

[0019] In some embodiments, the second platform comprises at least one second damping pin disposed in a second guide hole and which is able to move in said second orifice along the main direction of said second orifice, the heel of the first blade comprises a second covering wall extending from the first platform towards the second blade so as to at least partially cover the second platform while being radially spaced therefrom, and to cover the second damping pin.

[0020] Alternatively, the first covering wall could cover both the first and second damping pins. It is thus possible to modulate the number of orifices and damping pins according to the vibration modes and the desired damping level.

[0021] In some embodiments, the first and second blades comprise two wipers, respectively an upstream wiper and a downstream wiper, extending radially outward from the first and second platforms.

[0022] The wipers are sealing devices capable of cooperating with an abradable track carried by a fixed ring surrounding the moving wheel comprising the moving blades.

[0023] In certain embodiments, the first covering wall is arranged axially between the two lips of the heel of the first blade, and the first damping pin is arranged axially between the two lips of the heel of the second blade.

[0024] In certain embodiments, the second covering wall is arranged axially upstream of the two lips of the first blade, and the second damping pin is arranged axially upstream of the two lips of the second blade.

[0025] Alternatively, the second covering wall and the second damping pin may be arranged axially downstream of the two wipers of the blades. Alternatively, covering walls and damping pins could be arranged both upstream of the two wipers, between the two wipers and downstream of the two wipers. It is thus possible to modulate the number of covering walls, orifices and damping pins according to the vibration modes and the desired damping level, in the case of moving blades such as turbine or compressor moving blades, comprising sealing wipers.

[0026] In certain embodiments, at least one of the two wipers of the first blade comprises a main portion and a protrusion extending in projection towards the second blade from the main portion so as to at least partially cover the second platform, said at least one of the two wipers thus forming the first covering wall, the protrusion covering the first damping pin which extends into one of the two wipers of the second blade.

[0027] The fact of using an element already present on the blade, namely the sealing lip, to manufacture the first covering wall, makes it possible to further simplify the implementation of the damping device. It is understood in this regard that the shape of the lip of the second blade where the first orifice receiving the first pin is formed, is adapted to take into account the presence of the protrusion partially covering the second platform.

[0028] In some embodiments, the heel of the second blade comprises a second covering wall extending from the second platform towards the first blade so as to at least partially cover the first platform while being radially spaced therefrom, the heel of the first blade comprising a second damping pin disposed in the first platform and being capable of moving along the radial direction, a movement of the second pin in the radial direction being limited by the second covering wall of the heel of the second blade.

[0029] It is understood that according to this embodiment, the first blade and the second blade each comprise a covering wall extending towards the circumferentially adjacent blade in a crisscross configuration, the heel of each further comprising a damping pin. The contact areas between the first blade and the second blade are thus doubled, which further improves the damping.

[0030] In some embodiments, the bladed assembly comprises a third blade circumferentially adjacent to the second blade such that the second blade is disposed between the first blade and the third blade, the third blade having, at a radially outer end, a third platform, the heel of the second blade comprising a second covering wall extending from the second platform toward the third blade so as to at least partially cover the third platform while being radially spaced therefrom, a second damping pin being disposed in the third platform and being capable of moving along the radial direction, a movement of the second pin in the radial direction being limited by the second covering wall of the heel of the second blade.

[0031] In other words, the damping system between the first blade and the second blade by contact between the covering wall and the damping pin, is repeated between the second blade and the third blade. A contact zone is thus created between the adjacent blades, each blade making it possible to dampen the vibrations of the adjacent blade.

[0032] Furthermore, in certain embodiments, the bladed assembly comprises a plurality of blades circumferentially adjacent to each other, each blade having a covering wall extending towards the circumferentially adjacent blade, and each blade comprising a guide orifice and a damping pin housed in said orifice and covered by the covering wall of the adjacent blade. A contact zone is thus formed between each blade, which makes it possible to improve the damping of vibrations over the entire crown of blades.

[0033] In certain embodiments, in a plane perpendicular to the central axis and passing through the first guide orifice, the main direction of the first guide orifice forms, with the radial direction, a first angle between -75° and +75°, and, in a plane comprising the central axis and passing through the first guide orifice, the main direction of the guide orifice forms, with the radial direction, a second angle between -75° and +75°.

[0034] It is understood that these values ​​also apply to the other guide orifices, when the platform(s) comprise a plurality of guide orifices. In other words, the main direction of the first orifice, and therefore the damping pin housed in the latter, may be slightly inclined relative to the radial direction. This makes it possible to recover part of the centrifugal force exerted on the pin, and thus to increase the contact force between the pin and its guide surface. The relative radial or circumferential displacements between two circumferentially adjacent blade roots are thus better damped.

[0035] In some embodiments, when the first angle and / or the second angle are unaffected, a diameter of the first guide orifice is greater than a diameter of the first damping pin, so as to form a clearance between the first damping pin and the walls of the first orifice.

[0036] In the embodiments described above, the diameter of the guide orifice is slightly greater than the diameter of the damping pin to allow free movement of the latter in the main direction. In this embodiment, a greater clearance is formed between the walls of the orifice and the lateral faces of the damping pin. For example, a diameter of the first orifice is approximately 1.5 times greater than the diameter of the first pin housed in the first orifice. Since the first angle and / or the second are not affected, the walls of the first orifice are necessarily inclined, such that in operation, the centrifugal acceleration permanently presses the damping pin against both the wall of the first orifice and the covering wall of the adjacent blade. This makes it possible to increase the friction surfaces, and thus to further improve the damping.

[0037] The present disclosure also relates to an aircraft turbomachine turbine comprising a bladed assembly according to any one of the preceding embodiments, the turbomachine turbine being a low pressure turbine. Brief description of the drawings

[0038] The invention and its advantages will be better understood upon reading the detailed description given below of different embodiments of the invention given as non-limiting examples. This description refers to the appended pages of figures, in which:

[0039] [Fig-1] [Fig.l] represents a schematic view in longitudinal section of a tur- bomachine;

[0040] [Fig.2] [Fig.2] represents a schematic perspective view of a set bladed according to a first embodiment of the invention;

[0041] [Fig.3] [Fig.3] represents a schematic view, in a perpendicular section plane dicular to a central axis of the turbomachine, of the bladed assembly of [Fig.2];

[0042] [Fig.4] [Fig.4] represents a schematic view, in a section plane parallel to the central axis of the turbomachine, of a modified example of the bladed assembly of the first embodiment;

[0043] [Fig.5] [Fig.5] represents a schematic view, in a section plane parallel to the central axis of the turbomachine, of another modified example of the bladed assembly of the first embodiment;

[0044] [Fig.6] [Fig.6] represents a schematic perspective view of a set bladed according to a second embodiment of the invention;

[0045] [Fig.7] [Fig.7] represents a schematic perspective view of a set bladed according to a third embodiment of the invention;

[0046] [Fig.8] [Fig.8] represents a schematic view of a bladed assembly according to a fourth embodiment of the invention a) in a section plane perpendicular to the central axis of the turbomachine, and b) in a section plane parallel to the central axis of the turbomachine;

[0047] [Fig.9] [Fig.9] represents a schematic view of a bladed assembly according to a fifth embodiment of the invention, in a section plane perpendicular to the central axis of the turbomachine;

[0048] [Fig. 10] [Fig. 10] represents a schematic view of a bladed assembly according to a sixth embodiment of the invention, in a section plane perpendicular to the central axis of the turbomachine;

[0049] [Fig. 11] [Fig. 11] represents a schematic view of a bladed assembly according to a seventh embodiment of the invention, in a section plane perpendicular to the central axis of the turbomachine;

[0050] [Fig. 12] [Fig. 12] shows side views of different examples of damping pin structures according to the invention. Description of the embodiments

[0051] In the remainder of the description, the terms “upstream” and “downstream” are subsequently defined with respect to the direction of flow of the gases through a turbomachine, indicated by the arrow F in [Fig. 1] and the following figures, representing the flow of the hot gases in the combustion chamber 4. Furthermore, the terms “internal” and “external” are considered along a radial direction R perpendicular to the central axis X.

[0052] [Fig.l] illustrates a double-flow turbomachine 100 comprising in a known manner from upstream to downstream successively at least one fan S, a gas turbine engine part successively comprising at least one low-pressure compressor stage 2, high-pressure compressor stage 3, a combustion chamber 4, at least one high-pressure turbine stage 5 and low-pressure turbine stage 6. The rotors of the compressors 2, 3, of the turbines 5, 6 and of the fan S rotate around the central axis X of the turbomachine 100, and can be coupled together by different transmission and gear systems.

[0053] In the remainder of the description, reference is made to the low pressure turbine 6, in particular to moving blades of the low pressure turbine 6. It will be noted, however, that the invention can be applied equally well to moving blades of the high pressure turbine 5, or of the compressors 2, 3, or even to fixed blades.

[0054] A first embodiment of the invention is described in the remainder of the description, with reference to Figures 2 to 5.

[0055] [Fig.2] schematically represents, in perspective, a bladed assembly 1 according to the first embodiment, and [Fig. 3] partially represents the bladed assembly 1 of [Fig. 2], in a section plane perpendicular to the central axis X and passing through the damping pin 41 described below. In this example, the bladed assembly comprises a first blade 10 and a second blade 20 circumferentially adjacent. The first blade 10 and the second blade 20 extend radially respectively between a root 11, 21 at an inner end, or root end, and a heel 12, 22 at an outer end, or tip end. A blade 13, 23, intended to be in contact with the hot air flow stream, extends between the root 11, 21 and the heel 12, 22.

[0056] The foot 11, 21 is intended to be fixed on a mobile turbine disk (not shown). The heel 12 of the first blade 10 comprises a first platform 121 fulfilling an aerodynamic function, its radially internal face 121b being intended to be in contact with the hot air flow stream. The heel 12 further comprises two wipers extending radially outward from a radially external face 121a of the first platform 121, in particular an upstream wiper 122a and a downstream wiper 122b. The wipers 122a, 122b fulfill a sealing function and are capable of cutting into a track of abradable material carried by a stator ring (not shown).

[0057] In the same way, the heel 22 of the second blade 20 comprises a second platform 221 and two wipers extending radially outwards from a radially external face 221a of the second platform 221, in particular an upstream wiper 222a and a downstream wiper 222b.

[0058] The first blade 10 and the second blade 20 are arranged adjacent to each other in the circumferential direction around the central axis X. Consequently, the respective heels 12, 22 of the first and second blades 10, 20 are also circumferentially adjacent to each other. Their upstream wipers 122a, 222a, and their downstream wipers 122b, 222b, are respectively opposite each other, at the same axial position along the central axis X.

[0059] It will also be noted that the blades 10, 20 may be made of metallic, ceramic, or ceramic matrix composite (CMC) materials. This remark also applies to the other embodiments described later in the description.

[0060] Furthermore, according to the first embodiment of the invention, the heel 12 of the first blade 10 comprises a first covering wall 31, extending from the first platform 121, more precisely from the radially external face 121a thereof, towards the second platform 221.

[0061] [Fig. 3] represents a sectional view of the bladed assembly 1, in a sectional plane perpendicular to the central axis X and arranged between the upstream 122a, 222a and downstream 122b, 222b lips, showing the arrangement of the first covering wall 31.

[0062] In this example, the first covering wall 31 extends circumferentially towards the second platform 221, so as to partially cover the latter, but without coming into contact with the latter. In particular, the first covering wall 31 has a curved shape so as to create a space S between the first covering wall 31 and the radially external face 221a of the second platform 221.

[0063] The first covering wall 31 is preferably in a single block with the first platform 121, and can be manufactured at the same time as the first platform 121 during the manufacture of the first blade 10, for example by additive manufacturing or by other known methods.

[0064] Furthermore, according to the first embodiment of the invention, the heel 22 of the second blade 20 comprises a first damping pin 41 and a first orifice 51. The first orifice 51 passes through the second platform 221 on either side thereof, opening onto both its radially external face 221a and its radially internal face 221b.

[0065] The first damping pin 41 is arranged in the first orifice 51. More precisely, the first damping pin 41 comprises a main portion 411 housed in the first orifice 51, and a head 412 arranged at a radially external end of the main portion 441. A diameter L of the head 412 is larger than a diameter d of the main portion 411, thus giving the damping pin 41 the appearance of an unthreaded screw. Furthermore, the diameter L is larger than the diameter D of the first orifice 51. An extraction of the damping pin 41 through the first orifice 51, radially inwards, is thus prevented, the head 412 coming into abutment against the radially external face 221a of the second platform 221.

[0066] Furthermore, the first orifice 51 and the first damping pin 41 are formed such that the diameter D of the first orifice 51 is slightly greater than the diameter d of the main portion 411, for example, d=0.9D. The first damping pin 41 is thus mounted floating in the first orifice 51 and can move freely inside the first orifice 51 from top to bottom, that is to say in a main direction P of the first orifice 51, which can correspond to the radial direction R.

[0067] In this example, the first damping pin 41, in particular the main portion 411, and the first orifice 51, have a cylindrical shape with a circular cross-section, the main direction P then being the center of the cylinder formed by the first orifice 51. This shape is however not limiting, the first orifice 51 and the main portion 411 being able to have a rectangular cross-section, or any other shape as long as the first damping pin 41 can move in the first orifice 51. Furthermore, the first damping pin 41 may be made of metal, for example an alloy of nickel and chromium, or cobalt, ceramic or CMC.

[0068] The first orifice 51 and the first damping pin 41 are covered by the first covering wall 31. In this respect, it will be noted that the first covering wall 31 can cover approximately 50% of the surface of the second platform 221, it being understood that it must necessarily be arranged radially above the first damping pin 4L.

[0069] Indeed, taking into account this arrangement, when the first damping pin 41 moves radially outwards, its head 412 comes into abutment against the first covering wall 31, in the configuration shown in [Fig. 3]. It will be noted in this regard that a total height H of the first damping pin 41 is strictly greater than the maximum space S existing between the first covering wall 31 and the radially external face 221a of the second platform 221. This makes it possible to prevent the first damping pin 41 from being extracted outwards via this space S.

[0070] Thus, the travel of the first damping pin 41, in particular of its head 412, is limited between the radially external face 221a of the second platform 221 and the first covering wall 31. In other words, when the engine is stopped, the first damping pin 41 can fall under the effect of gravity, being retained by its head 412 coming into abutment against the radially external face 221a of the second platform 221. When the engine is running and the blades 10, 20 are rotating, the centrifugal force tends to project the first pin 41 outwards, the first pin 41 being retained by its head 412 coming into abutment against the first covering wall 31.

[0071] In this operating configuration, the friction between the head 412 of the first pin 41 and the covering wall 31 creates a contact zone between the first blade 10 and the second blade 20, the contact force between the blades 10, 20 creating a damping of the vibrations, proportional to the rotation speed and therefore to the engine speed.

[0072] Furthermore, it is possible to modulate the position and the number of damping pins, depending on the vibration modes and the desired damping level.

[0073] For this purpose, [Fig.4] schematically represents the second blade 20 in a plane section parallel to the plane formed by the central axis X and the radial direction R, illustrating a second modified example of the first embodiment of the invention.

[0074] In the first example described above with reference to Figures 2 and 3, the heel 12 of the first blade 10 comprised a single covering wall, namely the first covering wall 31 disposed axially between the upstream lip 122a and the downstream lip 122b. In this modified example, the heel 12 of the first blade 10 further comprises a second covering wall 32 disposed upstream of the upstream lip 122a (not visible in [Fig. 4]), and a third covering wall 33 disposed downstream of the downstream lip 122b (not visible in [Fig. 4]). The second and third covering walls 32, 33 extend towards the second platform 221, partially covering it.

[0075] Furthermore, the heel 22 of the second platform 221 comprises a second orifice 52 upstream of the upstream lip 222a, in which is housed a second damping pin 42 covered by the second covering wall 32, and a third orifice 53 downstream of the downstream lip 222b, in which is housed a third damping pin 43 covered by the third covering wall 33.

[0076] The heel 22 of the second platform 221 further comprises a fourth orifice 54 between the upstream lip 222a and the downstream lip 222b, in which is housed a fourth damping pin 44 covered by the first covering wall 31. Thus, the first covering wall 31 covers both the first pin and the fourth damping pin 41, 44. In this example, the first damping pin 41 is arranged closer to the upstream lip 222a, and the fourth damping pin 44 is arranged closer to the downstream lip 222b.

[0077] Thus, in this example, when the engine is in operation, the four damping pins 41, 42, 43, 44 are projected outwards by centrifugal force and come into abutment against the covering walls 31, 32, 33, thus increasing the number of contact zones and therefore the damping generated.

[0078] [Fig. 5] schematically represents the second blade 20 in a section plane parallel to the plane formed by the central axis X and the radial direction R, illustrating a third modified example of the first embodiment of the invention.

[0079] The third example differs from the second example in that the heel 12 of the first blade 10 does not include a third covering wall, and the first covering wall 31 only covers the first damping pin 41, which is here arranged closer to the downstream lip 222b than to the upstream lip 222a.

[0080] These examples illustrate different ways of modulating the arrangement, number and position of the damping pins, but are not limiting, other arrangements being possible depending on the desired damping level.

[0081] [Fig. 6] schematically represents, in perspective, a bladed assembly 1 according to a second embodiment. According to this second embodiment, the upstream lip 122a of the heel 12 of the first blade 10, comprises a main portion 123 having substantially the same shapes and dimensions as the upstream lip 122a according to the first embodiment, and a protrusion 124 extending from the main portion 123 towards the second platform 221, so as to partially cover the latter.

[0082] The upstream wiper 122a thus forms a covering wall having the same function as the first covering wall 31 described in the first embodiment. In particular, the protrusion 124 is arranged so as to cover the first damping pin 41 (represented here schematically by a black circle). In this respect, the upstream wipers 122a, 222a of the blades 10, 20 respectively, being arranged at the same axial position along the central axis X, the first damping pin 41 is itself arranged at the level of the upstream wiper 222a.

[0083] More specifically, the shape of the upstream wiper 222a is modified so as to adapt to this arrangement. In particular, the upstream wiper 222a comprises a main portion 223 having the same radial height as the main portion 123 of the upstream wiper 122a, and a recessed portion 224 having a lower radial height than that of the main portion 223, and allowing the positioning of the protrusion 124. Thus, the first orifice (not visible in [Fig. 6]), in which the first damping pin 41 is housed, is formed in the recessed portion 224.

[0084] It will be noted that these modifications to the shape of the upstream wipers 122a, 222a could be applied instead of, or in addition to, the downstream wipers 122b, 222b, without departing from the scope of the invention. Furthermore, the other characteristics of the blades 10, 20, not mentioned in the description of the second embodiment, are identical to the first embodiment.

[0085] [Fig.7] schematically represents, in perspective, a bladed assembly 1 according to a third embodiment. This third embodiment differs from the first embodiment in that the heel 12, 22 of each blade 10, 20 comprises a covering wall and a damping pin.

[0086] More precisely, the heel 12 of the first blade 10 comprises a first covering wall 31, extending from the first platform 121 towards the second platform 221, and the heel 22 of the second blade 20 comprises a second covering wall 32, extending from the second platform 221 towards the first platform 121.

[0087] Furthermore, the heel 22 of the second blade 20 comprises a first damping pin 41 covered by the first covering wall 31, and the heel 12 of the first blade 10 comprises a second damping pin 42 (hidden in [Fig.7]) covered by the second covering wall 32.

[0088] Thus, the first and second covering walls 31, 32 are arranged in a crisscross manner. In this example, the first and second covering walls 31, 32 are arranged between the upstream 122a, 222a and downstream 122b, 222b lips, and are each narrower than the first covering wall 31 alone of the first embodiment ([Fig.2]).

[0089] In the embodiments described above, the main direction P of the guide orifice in which the damping pin(s) is housed is substantially vertical, i.e. aligned with the radial direction R. This configuration is however not limiting, the guide orifice and the damping pin being able to be inclined relative to the radial direction R.

[0090] A bladed assembly 1 according to a fourth embodiment is shown in [Fig.8], in a first section plane perpendicular to the central axis X and passing through the first damping pin 41 of the second blade 20 arranged between the upstream 122a, 222a and downstream 122b, 222b wipers (image a) of [Fig.8]), and in a second section plane parallel to the plane formed by the central axis X and the radial direction R and passing through the first damping pin 41 of the second blade 20 (image b) of [Fig.8]).

[0091] It will be noted that in this example, the arrangement of the first covering wall 31 is identical to that described in the first embodiment ([Fig.2] and [Fig.3]), in which a single covering wall 31 extends from the first platform 121 between the upstream and downstream lips 122a, 122b, towards the second platform 221, covering the first damping pin 41.

[0092] However, in this fourth embodiment, the orifice 51 is inclined in such a way that a first angle a is formed between the radial direction R and the main direction P in the first plane (more precisely the projection of the main direction P in this first plane), and a second angle [3 is formed between the radial direction R and the main direction P in the second plane (more precisely the projection of the main direction P in this second plane). Each of the first angle a and the second angle [3 is between -75° and +75°. When the engine is in operation, the pressure exerted by the damping pin 41 is proportional to the centrifugal force on the covering wall 31.

[0093] [Fig.9] schematically represents a bladed assembly 1 according to a fifth embodiment, in a first sectional plane similar to [Fig.8], image a). In this fifth embodiment, in a configuration in which the first angle a and / or the second angle [3 is non-zero in a manner similar to the fourth embodiment, the diameter D of the first guide orifice 51 is enlarged compared to the embodiments described previously.

[0094] More specifically, unlike the embodiments described previously in which the diameter D of the guide orifice 51 was slightly larger than the diameter d of the damping pin 41, in particular of the main portion 411, such that d=0.9D, the opening of the guide orifice 51 is enlarged in the fifth embodiment, such that d=0.5D, for example. Thus, when the engine is in operation, the centrifugal force pushes the main portion 411 to press against a wall 511 of the guide orifice 51, thereby creating a clearance J between the opposite wall 511 of the orifice 51 and the main portion 411.

[0095] Consequently, a first friction surface S1 is created between the damping pin 41 and the second blade 20, and a second friction surface S2 is created between the damping pin 41 and the first blade 10, thus improving the damping and limiting the wear of the parts by distributing the contact surfaces. It will be noted that although the diameter D of the orifice 51 is enlarged, the diameter L of the head 412 of the damping pin 41 remains greater than D, in order to maintain the damping pin 41 in its location.

[0096] [Fig. 10] schematically represents a bladed assembly 1 according to a sixth embodiment, in a sectional plane similar to [Fig. 3]. In this sixth embodiment, unlike the first embodiment, the first guide orifice 51 is not a through orifice. More precisely, the first orifice 51 opens onto the radially external face 221a of the second platform 221, but is blocked on the side of the radially internal face 221b, the first orifice 51 thus having a bottom 512.

[0097] Given this configuration, the presence of a head on the first damping pin 41, housed in the orifice 51, is no longer necessary. Indeed, the stroke of the first damping pin 41 is limited between the bottom 512 of the orifice 51 on the one hand, and the covering wall 31 on the other hand. Thus, the first damping pin 41 comprises only a portion similar to the main portion 411 described previously, without other elements, which makes it possible to further simplify the structure of the device.

[0098] In the examples described above with reference to the different embodiments, the bladed assembly 1 comprises two circumferentially adjacent blades. This configuration is not limiting, the invention also applying to configurations in which more blades are arranged circumferentially adjacent to each other.

[0099] In the example illustrated in [Fig. 11], the bladed assembly 1 according to a seventh embodiment comprises a third blade 30. In addition to the first covering wall 31 extending from the first platform 121 of the first blade 10 to the second platform 221 of the second blade 20 by covering the first damping pin 41, a second covering wall 32 extends from the second platform 221 to the third platform 321 of the third blade 30 by covering a second damping pin 42.

[0100] It will further be noted that the first blade 10 may also comprise a third damping pin 43 covered by a third covering wall 33 extending from an adjacent blade (not shown), and a fourth covering wall 34 may extend from the third platform 321 of the third blade 30 towards a circumferentially adjacent blade (not shown). In other words, all the blades of the crown forming a rotor stage of the turbomachine module (here the low-pressure turbine 6), distributed circumferentially around the central axis X while being circumferentially adjacent to each other, may comprise a covering wall extending from the platform of its root towards the circumferentially adjacent blade (in a clockwise direction for example), and have a damping pin covered by the covering wall of the circumferentially preceding blade (in said clockwise direction).

[0101] Furthermore, in the various embodiments described previously (except for the sixth embodiment described with reference to [Fig. 10]), the damping pin 41 is formed of two cylinders (the main portion 411 and the head 412) superimposed on each other. This shape is however not limiting. [Fig. 12] illustrates various examples of damping pin 41 structures also applying to the invention.

[0102] In each of these examples, the damping pin 41 also comprises a main portion 411 and a head 412. However, in image a) of [Fig. 12], the pin 41 also comprises a chamfered upper portion 413, on a face su upper end of the head 412. In image b) of [Fig.12], the pin 41 comprises a domed upper portion 414. In image c) of [Fig.12], the pin 41 comprises a pointed upper portion 415, the upper end of the pointed upper portion 415 being centered on the main direction P. This pointed shape makes it possible to dissipate more vibration energy.

[0103] In image d) of [Fig. 12], the pin 41 comprises an eccentric upper tip portion 416, the upper end of the upper tip portion 416 being eccentric relative to the main direction P. This off-axis structure makes it possible to create an additional rotational movement of the pin 41 around its axis during vibrations, and thus to create additional damping.

[0104] It will further be noted that these structures are formed on the upper face of the head 412, the latter being able to have a cylindrical shape, or a parallelepiped shape. This remark also applies to the pin structure described in the rest of the description. Furthermore, the pin 41 may be bi-material, the head 412, or the upper portions 413, 414, 415, 416, being formed of a material different from the main portion 411. Furthermore, the structures a), b), c) and d) of [Fig. 12] may also apply to the pin 41 of the sixth embodiment not comprising a head 412, the upper portions then being formed on the upper face of the main portion 411.

[0105] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Claims

1. A bladed assembly (1) of an aircraft turbomachine centered on a central axis (X), the bladed assembly (1) comprising a first blade (10) and a second blade (20) circumferentially adjacent, each extending in a radial direction (R) relative to the central axis (X), between a blade root (11, 21) at a root end, and a heel (12, 22) at a tip end radially opposite the root end, the heel (12) of the first blade (10) comprising a first platform (121) and the heel (22) of the second blade (20) comprising a second platform (221), the heel (12) of the first blade (10) comprising a first covering wall (31) extending from the first platform (121) towards the second blade (20) so as to at least partially cover the second platform (221) being radially spaced therefrom,the heel (22) of the second blade (20) comprising a first damping pin (41) arranged in a first guide orifice (51) of the second platform (221), the first damping pin (41) being able to move in the first orifice (51) along a main direction (P) of said first orifice (51), a movement of the first pin (41) in the main direction (P) being limited by the first covering wall (31).,

2. A bladed assembly (1) according to claim 1, wherein the first orifice (51) is a through orifice, and the first damping pin (41) comprises a main portion (411) which extends longitudinally and which is housed in the first orifice (51), and a head (412) arranged between a radially external face (221a) of the second platform (221) and the first covering wall (31), the head (412) having a section, taken in a plane of section transverse to the main portion, wider than a section of the first orifice (51), taken in the plane of section transverse to the main portion, so as to prevent withdrawal of the first damping pin (41) radially inwards through the first orifice (51).

3. Bladed assembly (1) according to claim 1, in which the first orifice (51) does not open onto a radially internal face (221b) of the second platform (221), the first damping pin (41) comprising only a main portion (411) housed in the first orifice (51).

4. A bladed assembly (1) according to any one of claims 1 to 3, wherein the second platform (221) comprises a second damping pin (42) arranged in a second guide orifice (52) and which is capable of moving in said second orifice (52) along the main direction (P) of said second orifice (52), the heel (12) of the first blade (10) comprises a second covering wall (32) extending from the first platform (121) towards the second blade (20) so as to at least partially cover the second platform (221) while being radially spaced therefrom, and to cover the second damping pin (42).

5. A bladed assembly (1) according to any one of claims 1 to 4, wherein the first and second blades (10, 20) each comprise two wipers (122a, 122b, 222a, 222b), respectively an upstream wiper (122a, 222a) and a downstream wiper (122b, 222b), extending radially outwards from the first and second platforms (121, 221).

6. A bladed assembly (1) according to claim 5, wherein the first covering wall (31) is arranged axially between the two lips (122a, 122b) of the heel (12) of the first blade (10), and the first damping pin (41) is arranged axially between the two lips (222a, 222b) of the heel (22) of the second blade (20).

7. A bladed assembly (1) according to claim 4 and claim 6, wherein the second covering wall (32) is arranged axially upstream of the two licks (122a, 122b) of the first blade (10), and the second damping pin (42) is arranged axially upstream of the two licks (222a, 222b) of the second blade (20).

8. A bladed assembly (1) according to claim 5, wherein at least one of the two wipers (122a, 122b) of the first blade (10) comprises a main portion (123) and a protrusion (124) extending projecting towards the second blade (20) from the main portion (123) so as to at least partially cover the second platform (221), said at least one of the two wipers (122a, 122b) thus forming the first covering wall, the protrusion (124) covering the first damping pin (41) which extends into one of the two wipers (222a, 222b) of the second blade (20).

9. A bladed assembly (1) according to any one of claims 1 to 3, wherein the heel (22) of the second blade (20) comprises a second covering wall (32) extending from the second platform (221) towards the first blade (10) so as to cover at least at least in part the first platform (121) by being radially spaced therefrom, the heel (12) of the first blade (10) comprising a second damping pin (42) arranged in the first platform (121) and being able to move along the radial direction (R), a movement of the second pin (42) in the radial direction being limited by the second covering wall (32) of the heel (22) of the second blade (20).

10. A bladed assembly (1) according to any one of claims 1 to 3, comprising a third blade (30) circumferentially adjacent to the second blade (20) such that the second blade (20) is disposed between the first blade (10) and the third blade (30), the third blade (30) having, at a radially outer end, a third platform (321), the heel (22) of the second blade (20) comprising a second covering wall (32) extending from the second platform (221) towards the third blade (30) so as to at least partially cover the third platform (321) while being radially spaced therefrom, a second damping pin (42) being disposed in the third platform (321) and being capable of moving along the radial direction, a movement of the second damping pin (42) in the radial direction being limited by the second covering wall (32) of the heel of the second blade (20).

11. A bladed assembly (1) according to any one of claims 1 to 10, wherein, in a plane perpendicular to the central axis (X) and passing through the first guide orifice (51), the main direction (P) of the first guide orifice (51) forms, with the radial direction (R), a first angle (a) of between -75° and +75°, and, in a plane comprising the central axis (X) and passing through the first guide orifice (51), the main direction (P) of the guide orifice forms, with the radial direction (R), a second angle (|3) of between -75° and +75°.

12. / J. Bladed assembly (1) according to claim 11, wherein, when the first angle (a) and / or the second angle (|3) are not equal, a diameter (D) of the first guide orifice (51) is greater than a diameter (d) of the first damping pin (41), so as to form a clearance (J) between the first damping pin (41) and the walls (511) of the first orifice (51).

13. Aircraft turbomachine turbine (6) comprising a bladed assembly (1) according to any one of the preceding claims, the turbomachine turbine being a low pressure turbine (6).

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