Device for the damping of the bladed assembly of an aircraft turbomachine

Abstract

Device for damping the 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) comprising respectively a first and a second platform (121, 221), the heel (12) of the first blade (10) comprising a first cover 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 from it, the heel (22) of the second blade (20) comprising a first damping pin (41) disposed in a first guide hole (51) of the second platform (221), the first pin (41) damping element that can move in the first orifice (51) along a principal direction (P),a displacement of the first pin (41) in the principal direction (P) being limited by the first cover wall (31). Figure for the abbreviation: Fig. 2.

Description

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

[0001] The present description relates to the general field of turbine blades for modules of an aeronautical turbomachine such as an aircraft turbojet or turboprop engine. More specifically, it addresses the damping of 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 to a module, such as a compressor or turbine, comprising such an assembly. Previous technique

[0002] When turbomachinery engines are in operation, the blades comprising these turbomachinery, in particular the moving compressor and turbine blades, but not only, are subjected to vibrational stresses which must be taken into account to ensure the proper mechanical integrity of these blades, and to increase the life of the engine.

[0003] A known solution for limiting vibrational stresses on low-pressure turbine blades, for example, is the introduction of a friction contact technology between the root surfaces of circumferentially adjacent blades. This contact provides damping to the system. To achieve this, a specific cut is made to the lateral faces of the root surface, creating a protrusion on the upper surface and a symmetrical indentation on the lower surface. During assembly, contact is generated on these surfaces by means of an angular deformation of the blade, or "pretorsion." When the engine is running, the vibrations of the blades cause relative slippage at the contact areas between these surfaces. This relative slippage and the contact pressures induce damping by friction.

[0004] However, this solution can prove complex to implement during blade manufacturing and assembly, and offers limited flexibility. Furthermore, during operation, the contact forces between the flanges of circumferentially adjacent blades can change compared to the initial forces during assembly, due to the natural rotation of the blades (clockwise or counterclockwise) or the relative movements of the circumferentially adjacent flanges (moving closer together or further apart). To compensate for situations where contact pressures decrease during operation, it is necessary to amplify these contact pressures during assembly to maintain sufficient contact pressures during operation, and therefore adequate damping.

[0005] However, this adaptation results in static overstress, which can prove problematic in certain cases. In particular, blades made of ceramic materials or ceramic matrix composites (CMCs) are mechanically insensitive to pretorsion. On this type of blade, significant pretorsion during assembly induces high static stresses relative to what these blades are mechanically capable of withstanding, which can compromise their mechanical strength and lifespan. Furthermore, ceramic or CMC blades expand less than metallic blades. Consequently, during hot operation, the expansion of the flanges, the contact pressures between them, and therefore the damping effects, are less than for metallic blades.

[0006] There is therefore a need for a device which can at least partially overcome the aforementioned disadvantages, and which can effectively dampen vibration phenomena regardless of the material used for the blades. Description of the invention

[0007] The present description 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 with respect to the central axis, between a blade root at one root end, and a tail at one tip end radially opposite the root end, the tail of the first blade comprising a first platform and the tail of the second blade comprising a second platform, the tail of the first blade comprising a first cover wall extending from the first platform towards the second blade so as to at least partially cover the second platform while being radially spaced from it, the tail of the second blade comprising a first damping pin disposed in a first guide orifice of the second platform,The first damping pin is capable of moving within the first orifice along a principal direction of said first orifice, with the displacement of the first pin in the principal direction being limited by the first cover wall.

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

[0009] It is understood that the first blade and the second blade are adjacent to each other in the circumferential direction with respect 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 circum- differentially 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 platform) in contact with the internal gas flow in the air circulation vein, and a sealing function in the case of movable blades, in particular via the blades carried by the platforms.

[0011] It is understood that the first cover 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 cover wall typically forms a tongue extending from the first platform to the second platform, being curved so as to be radially spaced from said second platform which it covers.

[0012] Furthermore, the first damping pin is positioned in the first guide hole, formed through the second platform, in a floating manner. In other words, the pin can move by sliding up and down inside the first hole, that is, along the principal direction of the first hole, which is, for example, the central axis of the cylinder formed by the hole when the latter is cylindrical. However, the movement of the first pin in an extraction direction from the first hole, that is, radially outwards along the principal direction, is limited by the first cover wall, which at least partially covers the second platform. It is thus understood that the first cover wall acts as a stop limiting the travel of the first pin in the principal direction. In particular, the first cover wall prevents the pin from being extracted outwards from the first hole.

[0013] Given this arrangement, the first damping pin can be brought into contact with the first cover wall, either by initially positioning and locking it in this way, i.e., when cold during assembly, in the case of a fixed blade, or by the action 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 cover wall. The contact area thus created between the first and second blades dampens vibrations. In particular, the radial contact force between the damping pin and the cover wall, and consequently the damping, is determined by the centrifugal acceleration and therefore by the engine speed.

[0014] The invention thus makes it possible to ensure, regardless of the material used for the blade (metallic, ceramic or CMC), damping of vibrational phenomena by The upper part of a blade with a flange is damped by direct friction at the flange, without the need to pre-stress the blade and using simple methods. In particular, the cover plate and the damping pin are compact, lightweight components 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 requirements, as the contact points are known and predetermined. Furthermore, additional thicknesses can be easily added to the functional surfaces, particularly the damping pin and the cover plate, to compensate for wear.

[0015] In certain embodiments, the first orifice is through, and the first damping pin comprises a main portion which extends longitudinally and which is housed in the first orifice, and a head disposed between a radially external face of the second platform and the first cover wall, the head having a section, taken in a plane of cut transverse to the main portion, wider than a section of the first orifice, taken in the plane of cut transverse to the main portion, so as to prevent a 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 inner and radially outer faces of the second platform. The main portion may be cylindrical with a circular cross-section, although this shape is not limiting; the main portion may alternatively have a rectangular cross-section or another shape. The head is a simple shape to machine, making it possible to prevent the damping pin of the first orifice from retracting, particularly under the effect of gravity when the engine is stopped.

[0017] In some 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 opening is located only on the radially external face of the second platform, the first opening being closed on the internal side. Since the damping pin can no longer be extracted radially inwards, a head is no longer required. Consequently, the damping pin is formed solely by a main portion with a constant cross-section (for example, cylindrical) along its entire height. This solution further simplifies the manufacturing of the damping pin.

[0019] In some embodiments, the second platform includes at least one second damping pin disposed in a second guide hole and which is capable of moving in said second orifice along the main direction of said second orifice, the heel of the first blade includes a second cover wall extending from the first platform to the second blade so as to cover at least part of the second platform while being radially spaced from it, and to cover the second damping pin.

[0020] Alternatively, the first cover wall could cover both the first and second damping pins. This makes it 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 slicks, respectively an upstream slick and a downstream slick, extending radially outwards from the first and second platform.

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

[0023] In some embodiments, the first cover wall is arranged axially between the two slats of the heel of the first blade, and the first damping pin is arranged axially between the two slats of the heel of the second blade.

[0024] In some embodiments, the second cover wall is arranged axially upstream of the two scrapers of the first blade, and the second damping pin is arranged axially upstream of the two scrapers of the second blade.

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

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

[0027] Using an element already present on the blade, namely the sealing strip, to manufacture the first cover wall further simplifies the implementation of the damping device. In this regard, it is understood that the shape of the strip on the second blade, where the first opening receiving the first pin is formed, is adapted to accommodate the presence of the protrusion partially covering the second platform.

[0028] In some embodiments, the heel of the second blade includes a second cover wall extending from the second platform to the first blade so as to cover at least part of the first platform while being spaced radially from it, the heel of the first blade including a second damping pin disposed in the first platform and being able to move along the radial direction, a movement of the second pin in the radial direction being limited by the second cover wall of the heel of the second blade.

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

[0030] In certain 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 external end, a third platform, the heel of the second blade comprising a second cover wall extending from the second platform to the third blade so as to cover at least part of the third platform while being radially spaced from it, a second damping pin being disposed in the third platform and being able to move along the radial direction, a movement of the second pin in the radial direction being limited by the second cover wall of the heel of the second blade.

[0031] In other words, the damping system between the first and second blades, through contact between the cover wall and the damping pin, is repeated between the second and third blades. A contact zone is thus created between the adjacent blades, each blade damping 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 has a cover wall extending towards the circumferentially adjacent blade, and each blade includes a guide hole and a damping pin housed in said hole and covered by the cover wall of the adjacent blade. A contact zone is thus formed between each blade, which improves vibration damping across the entire blade ring.

[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 including 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 holes when the platform(s) comprise a plurality of guide holes. In other words, the principal direction of the first hole, and therefore the damping pin housed within it, can be slightly inclined relative to the radial direction. This allows for the recovery of some of the centrifugal force acting on the pin, and thus increases the contact force between the pin and its guide surface. The relative radial or circumferential displacements between two circumferentially adjacent blade flanges are therefore better damped.

[0035] In certain embodiments, when the first angle and / or the second angle are not harmed, a diameter of the first guide orifice is greater than a diameter of the first damping pin, so as to form a play 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 larger than the diameter of the damping pin to allow the latter to move freely in the principal direction. In this embodiment, a larger clearance is formed between the walls of the orifice and the lateral faces of the damping pin. For example, the diameter of the first orifice is approximately 1.5 times larger than the diameter of the first pin housed in the first orifice. Since the first angle and / or the second angle are not affected, the walls of the first orifice are necessarily inclined, such that during operation, the centrifugal acceleration constantly presses the damping pin against both the wall of the first orifice and the cover wall of the adjacent blade. This increases the friction surfaces and thus further improves the damping.

[0037] The present description also relates to an aircraft turbomachine turbine comprising a bladed assembly according to any 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 following detailed description of various embodiments of the invention, given by way of non-limiting examples. This description refers to the accompanying figure pages, on which:

[0039] [Fig-1] Fig. 1 represents a schematic longitudinal cross-sectional view of a tur- bomachine;

[0040] [Fig.2] Fig.2 represents a schematic perspective view of an assembly aubagé 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 cutting 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 cutting 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 an assembly aubagé according to a second embodiment of the invention;

[0045] [Fig.7] Fig.7 represents a schematic perspective view of an assembly aubagé 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 cutting plane perpendicular to the central axis of the turbomachine, and b) in a cutting 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 cutting plane perpendicular to the central axis of the turbomachine;

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

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

[0050] [Fig. 12] The [Fig. 12] represents side views of different examples of damping pin structures according to the invention. Description of the implementation methods

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

[0052] Fig. 1 illustrates a double-flow turbomachine 100 comprising, in a known manner, from upstream to downstream successively, at least one blower S, a gas turbine engine part comprising successively at least one stage of low-pressure compressor 2, high-pressure compressor 3, a combustion chamber 4, at least one stage of high-pressure turbine 5 and low-pressure turbine 6. The rotors of the compressors 2, 3, the turbines 5, 6 and the blower 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 following description, reference is made to the low pressure turbine 6, in particular to moving blades of the low pressure turbine 6. It should be noted, however, that the invention can be applied equally to moving blades of the high pressure turbine 5, or of compressors 2, 3, or even to fixed blades.

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

[0055] Figure 2 schematically represents, in perspective, a winged assembly 1 according to The first embodiment, and [Fig. 3] partially represents the bladed assembly 1 of [Fig. 2], in a cross-sectional 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 foot 11, 21 at an inner end, or foot 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 duct, extends between the foot 11, 21 and the heel 12, 22.

[0056] The foot 11, 21 is intended to be fixed to a movable turbine disk (not shown). The heel 12 of the first blade 10 comprises a first platform 121 fulfilling an aerodynamic function, its radially inner face 121b being intended to be in contact with the hot air flow duct. The heel 12 further comprises two blades extending radially outwards from a radially outer face 121a of the first platform 121, in particular an upstream blade 122a and a downstream blade 122b. The blades 122a, 122b perform a sealing function and are suitable for notching a track of abradable material carried by a stator ring (not shown).

[0057] Similarly, the heel 22 of the second blade 20 comprises a second platform 221 and two slats extending radially outwards from a radially external face 221a of the second platform 221, in particular an upstream slat 222a and a downstream slat 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 lugs 12, 22 of the first and second blades 10, 20 are also circumferentially adjacent to each other. Their upstream lugs 122a, 222a, and their downstream lugs 122b, 222b, are respectively opposite each other, at the same axial position along the central axis X.

[0059] It should also be noted that the blades 10, 20 can be made of metallic material, ceramic, or ceramic matrix composite (CMC). 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 cover wall 31, extending from the first platform 121, more precisely from the radially external face 121a thereof, to the second platform 221.

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

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

[0063] The first cover wall 31 is preferably in one piece 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 processes.

[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 both sides thereof, opening out both on its radially external face 221a and on its radially internal face 221b.

[0065] The first damping pin 41 is disposed 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 disposed 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. Extraction of the damping pin 41 through the first orifice 51, radially inward, is thus prevented, the head 412 abutting 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 larger than the diameter d of the main portion 411, for example, d=0.9D. The first damping pin 41 is thus mounted to float in the first orifice 51 and can move freely inside the first orifice 51 up and down, that is to say in a principal 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 principal direction P being the center of the cylinder formed by the first orifice 51. This shape is not, however, limiting, the first orifice 51 and the main portion 411 being able to have a rectangular cross-section, or any other shape provided that the first damping pin 41 can move within the first orifice 51. Furthermore, the first damping pin 41 may be made of metal, for example a nickel and chromium alloy, or cobalt, ceramic, or CMC.

[0068] The first orifice 51 and the first damping pin 41 are covered by the first cover wall 31. In this regard, it should be noted that the first cover 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, given this arrangement, when the first damping pin 41 moves radially outwards, its head 412 comes to rest against the first cover wall 31, in the configuration shown in [Fig. 3]. It should be noted in this regard that the total height H of the first damping pin 41 is strictly greater than the maximum space S existing between the first cover wall 31 and the radially external face 221a of the second platform 221. This prevents the first damping pin 41 from being pulled outwards through this space S.

[0070] Thus, the stroke of the first damping pin 41, in particular its head 412, is limited between the radially external face 221a of the second platform 221 and the first cover wall 31. In other words, when the engine is stopped, the The first damping pin 41 can fall under the effect of gravity, being held by its head 412 coming 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 held by its head 412 coming against the first cover wall 31.

[0071] In this operating configuration, the friction between the head 412 of the first pin 41 and the cover 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 speed of rotation and therefore to the engine speed.

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

[0073] To this end, [Fig.4] schematically represents the second blade 20 in a plane of a cut 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 cover wall, namely the first cover wall 31 arranged axially between the upstream flap 122a and the downstream flap 122b. In this modified example, the heel 12 of the first blade 10 further comprises a second cover wall 32 arranged upstream of the upstream flap 122a (not visible in [Fig. 4]), and a third cover wall 33 arranged downstream of the downstream flap 122b (not visible in [Fig. 4]). The second and third cover walls 32, 33 extend towards the second platform 221, partially covering it.

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

[0076] The heel 22 of the second platform 221 further includes a fourth opening 54 between the upstream slat 222a and the downstream slat 222b, in which is housed a fourth damping pin 44 covered by the first cover wall 31. Thus, the first cover 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 slat 222a, and the fourth damping pin 44 is arranged closer to the downstream slat 222b.

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

[0078] Fig. 5 schematically represents the second blade 20 in a cutting 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 cover wall, and the first cover wall 31 covers only the first damping pin 41, which is here arranged closer to the downstream skid 222b than to the upstream skid 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 conceivable depending on the desired level of damping.

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

[0082] The upstream blade 122a thus forms a cover wall having the same function as the first cover 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 blades 122a, 222a of the blades 10, 20 respectively, being arranged in the same axial position along the central axis X, the first damping pin 41 is itself located at the level of the upstream blade 222a.

[0083] More specifically, the shape of the upstream slit 222a is modified to adapt to this arrangement. In particular, the upstream slit 222a comprises a main portion 223 having the same radial height as the main portion 123 of the upstream slit 122a, and a recessed portion 224 having a lower radial height than 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 should be noted that these modifications to the shape of the upstream blades 122a, 222a could be applied instead of, or in addition to, the downstream blades 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] Figure 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 cover wall and a damping pin.

[0086] More specifically, the heel 12 of the first blade 10 includes a first cover wall 31, extending from the first platform 121 to the second platform 221, and the heel 22 of the second blade 20 includes a second cover wall 32, extending from the second platform 221 to the first platform 121.

[0087] Furthermore, the heel 22 of the second blade 20 includes a first damping pin 41 covered by the first cover wall 31, and the heel 12 of the first blade 10 includes a second damping pin 42 (masked on the [Fig.7]) covered by the second cover wall 32.

[0088] Thus, the first and second cover walls 31, 32 are arranged in an interlaced manner. In this example, the first and second cover walls 31, 32 are positioned between the upstream sluice gates 122a, 222a and downstream 122b, 222b, and are each narrower than the first cover wall 31 alone in the first embodiment ([Fig.2]).

[0089] In the embodiments described above, the principal 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 not limiting however, the guide orifice and the damping pin may be inclined with respect 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 scrapers 122a, 222a and downstream scrapers 122b, 222b (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 cover wall 31 is identical to that described in the first embodiment ([Fig.2] and [Fig.3]), in which a single cover wall 31 extends from the first platform 121 between the upstream and downstream ledges 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 A first angle α is formed between the radial direction R and the principal direction P in the first plane (more precisely, the projection of the principal direction P onto this first plane), and a second angle θ is formed between the radial direction R and the principal direction P in the second plane (more precisely, the projection of the principal direction P onto this second plane). Each of the first angle α and the second angle θ is between -75° and +75°. When the engine is running, the pressure exerted by the damping pin 41 is proportional to the centrifugal force on the cover wall 31.

[0093] Figure 9 schematically represents a bladed assembly 1 along a fifth embodiment, in a first cutting 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 similar way 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 above 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 motor is running, the centrifugal force pushes the main portion 411 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 SI 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 damping and limiting wear on the parts by distributing the contact surfaces. It should 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 keep the damping pin 41 in its position.

[0096] Figure 10 schematically represents a bladed assembly 1 according to a sixth embodiment, in a cross-section similar to Figure 3. In this sixth embodiment, unlike the first embodiment, the first guide orifice 51 is not through-hole. More precisely, the first orifice 51 opens onto the radially external face 221a of the second platform 221, but is blocked on 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 The first damping pin 41 is limited between the bottom 512 of the orifice 51 on one side, and the cover wall 31 on the other. Thus, the first damping pin 41 comprises only a portion similar to the main portion 411 described previously, without any other elements, which further simplifies 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 applies to configurations in which more blades are arranged circumferentially adjacent to one another.

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

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

[0101] Furthermore, in the various embodiments described above (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 one on top of the other. This shape is not, however, limiting. [Fig. 12] illustrates various examples of damping pin 41 structures also applicable 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 part of the head 412. In image b) of [Fig.12], the pin 41 includes a convex upper portion 414. In image c) of [Fig.12], the pin 41 includes a pointed upper portion 415, the upper end of the pointed upper portion 415 being centered on the principal direction P. This pointed shape allows for the dissipation of more vibration energy.

[0103] In image d) of [Fig. 12], the pin 41 includes an eccentric pointed upper portion 416, the upper end of the pointed upper portion 416 being eccentric with respect to the principal direction P. This off-center structure allows for the creation of an additional rotational movement of the pin 41 around its axis during vibrations, and thus to create additional damping.

[0104] It should also be noted that these structures are formed on the upper face of the head 412, the latter being able to have either a cylindrical or a parallelepiped shape. This observation also applies to the pin structure described in the remainder of the description. Furthermore, the pin 41 can be made of two materials, the head 412, or the upper portions 413, 414, 415, 416, being formed of a material different from the main portion 411. In addition, structures a), b), c), and d) of [Fig. 12] can also be applied 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 embodiments, it is evident that modifications and changes can 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 embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

Claims

Demands

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

2. Bladed assembly (1) according to claim 1, wherein the first orifice (51) is through, 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) disposed between a radially external face (221a) of the second platform (221) and the first cover wall (31), the head (412) having a section, taken in a plane of cut transverse to the main portion, wider than a section of the first orifice (51), taken in the plane of cut transverse to the main portion, so as to prevent a withdrawal of the first damping pin (41) radially inwards through the first orifice (51).

3. Bladed assembly (1) according to claim 1, wherein the first orifice (51) is not opening 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. Bladed assembly (1) according to any one of claims 1 to 3, in which the second platform (221) includes a second damping pin (42) disposed in a second guide orifice (52) and which is able to move in said second orifice (52) along the main direction (P) of said second orifice (52), the heel (12) of the first blade (10) includes a second cover wall (32) extending from the first platform (121) to the second blade (20) so as to cover at least part of the second platform (221) by being radially spaced from it, and to cover the second damping pin (42).

5. Bladed assembly (1) according to any one of claims 1 to 4, wherein the first and second blade (10, 20) each comprise two slats (122a, 122b, 222a, 222b), respectively an upstream slat (122a, 222a) and a downstream slat (122b, 222b), extending radially outwards from the first and second platform (121, 221).

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

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

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

9. Bladed assembly (1) according to any one of claims 1 to 3, wherein the heel (22) of the second blade (20) comprises a second cover wall (32) extending from the second platform (221) to the first blade (10) so as to cover at less in part the first platform (121) by being spaced radially from it, the heel (12) of the first blade (10) comprising a second damping pin (42) disposed 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 cover 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 one radially external end, a third platform (321), the heel (22) of the second blade (20) comprising a second cover wall (32) extending from the second platform (221) to the third blade (30) so as to at least partially cover the third platform (321) while being radially spaced from it, a second damping pin (42) being disposed in the third platform (321) and being capable of moving along the radial direction, a displacement of the second damping pin (42) in the radial direction being limited by the second cover 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 principal direction (P) of the first guide orifice (51) forms, with the radial direction (R), a first angle (α) between -75° and +75°, and, in a plane including the central axis (X) and passing through the first guide orifice (51), the principal direction (P) of the guide orifice forms, with the radial direction (R), a second angle (α) 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 harmed, 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).

Images