ASSEMBLY INCLUDING A SIGNAL MOUNTED ON A DISC OF A MOVING WHEEL

Abstract

SHINKING ASSEMBLY FOR A MOVING WHEEL One aspect of the invention relates to an assembly comprising a shim (1) mounted in a notch (23) of a disc (2), wherein the shim (1) comprises a base (10) in contact with the bottom surface (23c) of the notch 23. Figure to be published with the abbreviation: Figure 2

Description

Title of the invention: ASSEMBLY COMPRISING A CLINT MOUNTED ON A DISC OF A MOVING WHEEL TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of the shims of a moving wheel to protect the turbine blades.

[0002] The present invention relates to a shim mounted on a turbine disc for the protection of a moving blade and a turbomachine disc of a moving wheel. The present invention further relates to the moving wheel. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Conventionally, an axial turbine of a turbomachine consists of a succession of axial stages (along the axis of gas flow) arranged one behind the other. Each stage comprises a bladed runner forming the rotor and a bladed distributor forming the stator. The runner is rotated opposite the corresponding distributor.

[0004] The movable wheel is classically made up of an annular disk centered on the axis of rotation of the wheel, comprising notches having a honeycomb shape and a plurality of movable blades each comprising an attachment member called in the following a blade foot in the notch forming a housing.

[0005] In the contact areas between the foot of each movable blade and the surface of the adjacent teeth delimiting the notch in the shape of a honeycomb in the disc housing this foot, several types of stresses are exerted.

[0006] One encounters, in particular, "fretting," that is, contact wear, which is the consequence of the repetitive friction of one part on another, the resulting frictional forces potentially causing damage to the material through various fatigue processes. This phenomenon is particularly noticeable in the case of contact between two parts, for example, metallic or CMC parts.

[0007] These areas are therefore subject to a significant tendency to damage the material, as well as to wear of the bearing surfaces of the blade foot which are the areas in contact with the honeycomb-shaped surface delimiting the notch formed between the teeth of the disc, or even deformation of these contact areas.

[0008] Furthermore, the level of local stresses is very high due to the coefficient of friction at the interface between the contacting walls of the blade root and the honeycomb surface formed by the two teeth, which is a metal-on-metal contact. In the following, this interface is referred to as the blade root span and the honeycomb span.

[0009] To solve these problems, we seek in particular to strengthen resistance to the wear of the surfaces in contact and to reduce the coefficient of friction.

[0010] To do this, generally a protective part is used which can be a consumable, formed of one or more metal shims fitting the foot of the blade over the entire longitudinal length of the bulb of the blade foot.

[0011] With this type of solution, it is possible to reduce the coefficient of friction and it is possible to change the shim instead of an entire blade.

[0012] For example, document EP2042689A1 proposes to use an assembly with a metallic shim between a blade foot and a disc.

[0013] In prior art shims, these are held in position on the awl feet by two folded tabs protruding from the base of the shim located at the bottom of the awl foot against one face of the awl foot.

[0014] During turbine operation, axial displacement of the shims has been observed in certain situations. This can damage the sensitive tabs due to their folding / unfolding during the shim assembly phase. The mechanical strength of the shim, particularly at the tabs, is too weak and cannot withstand the stresses generated by the blade during operation. The mechanical strength of the shim is linked, in particular, to thermal stresses generated by the repeated thermal expansion and contraction of the blade over the course of operating cycles. This, in turn, affects the blade root, which transmits temperature increases and decreases to the shim, causing it to expand and contract repeatedly, leading to its degradation.

[0015] This damage can in some cases lead to cutting and possible axial disengagement of the shims. Indeed, in these situations, once the tabs are cut, the shims can then disengage partially or totally from the blade feet.

[0016] The disengagement of the shims no longer ensures the mechanical integrity of the blade root and turbine disk. This axial disengagement of the shim therefore leaves at least a portion of the blade root unprotected, resulting in premature wear of the blade root instead of the shim, caused by fretting. Premature wear or a shim detected as disengaged can lead to engine removal for blade shim replacement, degradation of the blade / disk interface due to increased wear without shims, degradation of the blade runners due to impact with the disengaged shim, and thus increased maintenance time.

[0017] The cut tabs can also in certain situations end up in an air stream and damage shock-sensitive blades located downstream of the turbine.

[0018] It is also known in document EP1764480A1 as a sash whose tongue is formed by two tabs extending from the ends of the branches, joined together by a connecting piece, either welded, riveted, or fitted. Such a tab results in increased production costs, and furthermore, even if the connecting piece increases the tab's strength, it does not prevent one of the tabs from breaking at the end of one of the branches. In addition, thermal stresses on the connecting piece can cause the tab to tear.

[0019] It is also known from shims, notably in document EP2042689A1 filed by the applicant, that include a tab folded towards the rotor rather than towards the blade; however, the tab is still liable to unfold or tear and cause wear to at least a portion of the blade. Furthermore, in this document, there is a shim between the shim and the bottom of the disc slot. The shim therefore has its base between the shim and a surface of the blade root. A locking mechanism is mounted and held between an upstream edge of the shim and the blade root, so that the retaining tab is held between the locking mechanism and the blade root, thus preventing axial displacement of the shim relative to the blade root.

[0020] However, this solution is difficult to implement and is not always possible due to space constraints and mechanical resistance of the blade or disc.

[0021] There is therefore a need to reduce the friction between the blade foot and the honeycomb-shaped surface delimiting the notch in a simpler and / or safer way than those of the prior art. Summary of the invention

[0022] The invention offers a solution to at least one of the problems mentioned above, by allowing a shim to be positioned in a notch between two teeth of the disc and not on the foot of the blade.

[0023] A first aspect of the invention relates to an assembly comprising: • a rotating wheel disc of a turbomachine comprising: • an axis of rotation, • teeth, each comprising on either side, a first lateral surface and a second lateral surface, • notches between each tooth, • a bottom surface per notch connecting the first lateral surface of one tooth to the second lateral surface of the other adjacent tooth, forming the notch between them, • a first radial surface and a second radial surface formed on either side of the disc, defining the notches and teeth, • at least one sash mounted in a notch, comprising a surface external, partially covering the surfaces delimiting the notch, the shim comprising: • a base in contact with the bottom surface, • a first lateral branch and a second lateral branch connected to each other at the base, each of the lateral branches being in contact respectively with a part of the first lateral surface of a tooth delimiting the notch and with a part of the second lateral surface of the other tooth delimiting the notch, • a first axial retaining element of the shim against the first radial surface to retain the shim in the notch in the axial direction of the disc of the moving wheel.

[0024] Thus, the invention allows for a shim to be mounted in a notch of the disc and not on a blade foot as in the prior art, thereby reducing heat transfer from the blade to the shim since only the protective portion is in contact with the blade foot. This reduction in contact area with the blade foot compared to the prior art reduces the thermal stresses on the shim and therefore decreases the risk of tearing of the retaining elements. Furthermore, having a shim with a base extending axially along the entire length of the notch increases the length of the shim's protective portion, as it now includes the length of the honeycomb-shaped notch in the disc and no longer only the length of the blade foot, which is shorter than the notch.Finally, the first axial retaining element can have a larger surface area (both in length and width) than the axial retaining elements of the prior art, since those of the invention are not constrained by the dimensions of the blade root cross-section but by the dimensions of the disc. Indeed, on the one hand, the disc notch has a cross-section with a larger periphery than that of the blade root, and therefore allows for a longer axial retaining element at the fold, increasing its strength; and on the other hand, the radial surface of the disc (at the central level between two teeth or at the tooth level) also allows for a wider axial element compared to those of the prior art, which are delimited by the tooth cross-section being smaller than that of the disc. This increased surface area improves their performance during operation.

[0025] In addition to the characteristics just mentioned in the preceding paragraph, the assembly according to one aspect of the invention may have one or more complementary characteristics from among those mentioned in the following paragraphs, considered individually or according to all technically possible combinations:

[0026] According to one embodiment, the shim comprises a second axial retaining element of the shim abutting the second radial surface to retain the clattering in the notch in the axial direction of the disc of the movable wheel.

[0027] This allows the shim to be retained in both axial directions. Similarly, as with the first retaining element, having the second retaining element in contact with the disc reduces thermal stress compared to prior art shims where the second retaining element is in contact with the foot.

[0028] According to an example of this embodiment, the first axial retaining element and the second axial retaining element of the shim extend axially on either side of the base and are each abutted against respectively a central part of the first radial surface of the disc and a central part of the second radial surface to retain the shim in the notch in both axial directions of the disc of the moving wheel.

[0029] According to another example of this embodiment, the first axial retaining element and the second axial retaining element of the shim each extend axially on either side of the first lateral branch or the second lateral branch and each are abutted against respectively a radial tooth portion of the first radial surface of the disc and a radial tooth portion of the second radial surface, to retain the shim in the notch in both axial directions of the disc of the moving wheel.

[0030] According to one embodiment, the shim further comprises two other axial retaining elements per lateral branch extending axially on either side of the corresponding lateral branch, each of the other axial retaining elements being abutted against respectively a radial tooth portion of the first radial surface of the disc and a radial tooth portion of the second radial surface, to retain the shim in the notch in both axial directions of the disc of the moving wheel.

[0031] According to one embodiment, the shim is compressed in the notch by having its lateral branches constrained towards the inside of the shim. This allows the shim to be easily installed in the notch, making it possible to fold down the retaining element(s) without having to hold the shim in the notch.

[0032] According to one embodiment, the base of the shim comprises on each side a curved portion connected to the corresponding lateral branch, each curved portion being concave on the side of an internal surface of the shim, and in that each lateral branch comprises a protective portion extending from the curved portion, in contact with a bearing surface of the corresponding tooth.

[0033] A second aspect of the invention relates to a movable wheel comprising: • an assembly according to the first aspect of the invention with or without the com combination of the characteristics described in the different embodiments of the preceding paragraphs, and • at least one dawn, the dawn comprising: • an internal platform, • an aerodynamic blade extending radially from the internal platform, • a blade root extending radially from the platform opposite the aerodynamic blade, the blade root being mounted in a notch, the blade root has a bulbous shape comprising a bearing surface opposite the internal surface of the shim protection portion and an axial surface extending in an axial plane, opposite the platform, • a play between the internal surface at the base of the shim and the axial surface of the foot.

[0034] Thus, the invention makes it possible to reduce the stresses in at least one end of the neck of the paddle foot. BRIEF DESCRIPTION OF THE FIGURES

[0035] The figures are presented for illustrative purposes only and are in no way limiting of the invention.

[0036] [Fig. 1] is a perspective view of a shim of an assembly according to a first embodiment of the invention.

[0037] [Fig.2] is a radial view of part of an assembly according to the first embodiment of which part of a disk of the assembly is represented with a shim shown in [Fig.1] mounted in a notch of the disk.

[0038] [Fig.3] is a radial view of part of a moving wheel comprising the whole of [Fig.2] along an opposite face.

[0039] [Fig.4] is a perspective view of a shim of an assembly according to a second embodiment of the invention.

[0040] [Fig. 5] is a radial view of part of an assembly according to the second embodiment, of which part of a disk of the assembly is shown with a shim shown in [Fig. 1] mounted in a notch of the disk. DETAILED DESCRIPTION

[0041] Unless otherwise specified, the same element appearing on different figures presents a unique reference.

[0042] The invention relates to an assembly comprising a shim mounted in a notch of a disc to protect against friction between a foot of a movable turbine blade and the disc, and to a movable turbine wheel comprising a movable blade having its foot inserted in the notch with such a shim between notch and foot spans.

[0043] A first aspect of the invention relates to an assembly according to a first embodiment, a portion of which is shown radially in [Fig. 2]. The assembly comprises a disk 2 and a shim 1, shown alone in perspective in [Fig. 1]. The disk 2 of the rotating turbomachine wheel includes a rotation axis (not shown) and, at its outer periphery, teeth, a portion of a first tooth 21 and a portion of a second tooth 21' adjacent to the first tooth 21 are shown in [Fig. 2]. This [Fig. 2] is a radial view of the assembly, representing a first radial surface 2c of the disk 2 and a first lateral edge 14c of the shim 1.

[0044] Each of the teeth 21, 21' comprises on each side, a first lateral surface 21a visible on the first tooth 21 and a second lateral surface 21b visible on the second tooth 21'.

[0045] The disk 2 thus includes notches 23 between each tooth 21, 21', of which only one notch 23 is shown in [Fig.2].

[0046] The disc 2 includes a bottom surface 23c per notch 23. This bottom surface 23c is connected to the first lateral surface 21a of the first tooth 21 and to the second lateral surface 21b of the second tooth 21' thus delimiting the notch 23 between them.

[0047] The shim 1 mounted in the notch 23 covers the bottom surface 23c and part of the two lateral surfaces 21a, 21b. More specifically, the shim comprises an internal surface li and an external surface le opposite the internal surface li, the external surface le of which is in contact with or in contact with the bottom surface 23c and is in contact with part of the two lateral surfaces 21a, 21b.

[0048] The shim 1 visible on the [Fig.1] in perspective therefore includes a base 10 such that the external surface at the level of the base 10 is represented on the [Fig.2] in contact with the bottom surface 23c.

[0049] The flash 1 further comprises a first lateral branch 12a and a second lateral branch 12b connected to each other by the base 10.

[0050] The external surface le, at the level of the first lateral branch 12a, is in contact with a part of the first lateral surface 21a of the first tooth 21 and at the level of the second lateral branch 12b is in contact with a part of the second lateral surface 21b of the second tooth 21'.

[0051] The parts, edge, portions of the tinsel on the side of the first lateral branch 12a include a reference with the letter "a" and those on the side of the second lateral branch 12b include a reference with the letter "b".

[0052] Each of the two lateral branches 12a, 12b extends from and along the base 10, i.e. are contiguous with each other at the base 10.

[0053] The shim 1 visible on [Fig.1] is therefore intended to be inserted into a notch 23 visible on [Fig.2].

[0054] The shim 1 includes at least a first axial retaining element 15c of the shim 1 against the first radial surface 2c of the disc 2, to retain the shim 1 in the notch 23 in the axial direction of the disc 2 of the movable wheel.

[0055] In this case, the shim 1 includes a second axial retaining element 15d axially opposite the first axial retaining element 15c, visible in [Fig. 1], as well as in [Fig. 3] representing a radial view of the second lateral edge 14d of the shim 1 and the second radial surface 2d of the disc 2. [Fig. 3] represents, in particular, a second aspect of the invention, which relates to a movable wheel, a part of which is shown in [Fig. 3] comprising the assembly according to the first embodiment as well as a blade 3 comprising a blade foot 32 inserted in the shim 1 in the notch 23.

[0056] The shim 1 is surrounded by a bearing surface of the first tooth 21 and a bearing surface of the second tooth 21' to protect a bearing surface of a foot 31 of a movable blade 3 mounted in the notch 23. The [Fig.3] represents a radial and partial view of an example of a movable wheel which includes the assembly, i.e. the disc 2 comprising notches 23 covered by shims 1 and blades 3 comprising their feet 32 ​​inserted in notches 23 of the disc 2 and therefore at least a part inside the shim 1.

[0057] Each of the two lateral branches 12a, 12b includes a longitudinal edge 122a, 122b opposite the base 10. The first lateral edge 14c and the second lateral edge 14d, longitudinally opposed to each other, form the periphery of the flash 1 with the two longitudinal edges 122a, 112b.

[0058] In this example, each of the two lateral branches 12a, 12b comprises a radial planar portion 120a, 120b extending along the longitudinal edges 122a, 112b in contact each with an upper part of the corresponding tooth 21, 21'.

[0059] Each of the two lateral branches 12a, 12b further comprises a protective portion 124a, 124b extending longitudinally between the radial planar portion 120a, 120b and the base 10. More precisely, each protective portion 124a, 124b extends radially from the base 10 to the radial planar portion 120a, 120b towards the other protective portion 124b, 124a of the other lateral branch 12b.

[0060] The protective portions 124a, 124b are inclined more towards each other than the radial planar portions 120a, 120b are inclined towards each other, that is to say, the angle formed between the protective portions 124a, 124b is greater than that formed between the radial planar portions 120a, 120b, which in this example are parallel. By "parallel" radial planar portions, it is understood that each comprises a surface extending in a plane parallel ± 3° to the other plane in which the other surface of the other radial planar portion extends.

[0061] A fold is formed in each portion of protection 124a, 124b at the level of its delineation connection with the corresponding radial flat portion 120a, 120b. In particular, each protective portion 124a, 124b comprises a curved portion 1240a, 1240b, (referenced on [Fig.2]) having a longitudinal axis outside the flashing 1 connected to the radial flat portion 120a, 120b.

[0062] Each protective portion 124a, 124b, is intended to protect the foot 32 of the blade 3, in particular to be sandwiched between a bearing of the foot 32 of the blade 3 and a bearing of the tooth 21, 21'.

[0063] Finally, in this embodiment, the base 10 comprises two curved portions 10a, 10b opposite each other, the axis of which extends longitudinally on the side of the internal surface li, each of the two curved portions 10a, 10b being connected to a protective portion 124a, 124b of the corresponding lateral branch 12a, 12b.

[0064] As can be seen in figures 2 and 3, in this example, the shim 1 is mounted in the notch 23 with its entire external surface in contact with the disc 2, but in reality a part of this surface can be in contact with the disc 2, at least a part at the base 10 and two parts which are each at the level of the corresponding protective portion 124a, 124b in contact with the bearing surface of the lateral surface 21a, 21b of the corresponding tooth 21, 21'.

[0065] As can be seen in [Fig.3], the internal surface li comprises only those parts at the level of each portion of protection 124a, 124b in contact with the foot 32 of blades 3, in particular in contact with the bearing surfaces of the foot 23 of blades 3.

[0066] The movable wheel therefore includes a play J1 between the internal surface li at the level of the base 10 of the shim 1 and the axial surface 32c of the foot 32.

[0067] Furthermore, in this example, one can also see a gap between the internal surface li at the level of the radial flat portions 120a, 120b of the shim 1 and a restricted cross-section area of ​​the foot 32, contiguous and extending from the platform 39 towards a main bulbous shape of the foot 32. The restricted cross-section area of ​​the foot 32 is therefore located between the spans and the platform. In this example, the restricted cross-section area of ​​the foot 32 comprises flat surfaces.

[0068] The main bulb shape of the foot 32 includes the bearings sandwiching the protective portions 124a, 124b of the flashing 1 with the disc 2.

[0069] The shim 1 is compressed in the notch 23 by including its lateral branches 12a, 12b constrained towards the interior of the shim 1.

[0070] In this first embodiment, the first axial retaining element 15c and the second axial retaining element 15d each extend longitudinally on either side of the base 10, that is, they extend respectively from the first lateral edge 14c and the second lateral edge 14d at the level of the base. The first and second axial retaining elements 15c, 15d are each folded while abutting against, respectively, a central portion 20c of the first radial surface 2c of the disk 2 and a portion central 20d of the second radial surface 2d to retain the shim 1 in the notch 23 in both axial directions of the disc 2 of the movable wheel.

[0071] Of course, these axial support elements could extend from the lateral branches from the first and second lateral edges 14c, 14d.

[0072] Fig. 5 represents a radial view of part of a movable wheel comprising an assembly according to a second embodiment.

[0073] The assembly according to the second embodiment is identical to the assembly of the first embodiment except with regard to the tinsel 1' shown in perspective on [Fig.4].

[0074] The shim 1' of this assembly according to the second embodiment is identical to the shim 1 of the assembly of the first embodiment except that this shim 1' further comprises additional axial support elements 15ac, 15bc, 15ad, 15bd; in this example, there are four of them. In this example of this second embodiment, the shim thus comprises two additional axial support elements 15ac, 15ad, 15ad, 15bd per lateral branch 12a, 12b.

[0075] Each axial retaining element 15c, 15d, 15ac, 15bc, 15ad, 15bd is in contact with the corresponding first and second radial surfaces 2c, 2d. The third and fourth axial retaining elements 15ac, 15bc extending respectively from the first and second lateral branches 12a, 12b from the first lateral edge 14c, are each in contact with respectively a radial part of tooth 215c, 215c' (not visible on [Fig.5], but referenced on [Fig.2]) of the first radial surface 2c of disc 2. The fifth and sixth axial retaining elements 15ad, 15bd extending respectively from the first and second lateral branches 12a, 12b from the second lateral edge 14d, are each in contact with respectively a radial part 215d, 215d' of tooth, visible on [Fig.5]. Each radial part of the tooth delimiting 215c, 215c', 215d, 215d' forms a radial surface of tooth 21.

[0076] In these two examples, the clincher 1 is symmetrical. The clincher 1 therefore comprises in this example two axial retaining elements 15ac, 15bc on the side of the first lateral edge 14c and two other axial retaining elements 15ad, 15bd on the side of the second lateral edge 14d symmetrically and the axial retaining elements 15c, 15 are located at the center of the first and second lateral edges 14c, 14d.

[0077] In Figures 1 and 4, in both embodiments, the axial retaining elements 15c, 15d, 15ac, 15bc, 15ad, 15bd are shown folded. Before being mounted in the notch 23, each axial retaining element 15c, 15d, 15ac, 15bc, 15ad, 15bd can extend along the base 10 or the lateral arms 12a, 12b. Each axial retaining element 15ac, 15bc, 15ad, 15bd thus forms a tab that abuts against a first and second radial surface 2c, 2d of the disk 2 as shown in Figures 2, 3 and 5.

[0078] Thus, thanks to the mounting of the shims 1 each mounted in a dedicated notch 23 of the disc 2, it is possible to increase the life of the blades 3 and the shims 1.

Claims

Demands

1. Set comprising: - a disc (2) of a rotating turbomachine wheel comprising: • an axis of rotation, • teeth (21, 21') each comprising on either side, a first lateral surface (21a) and a second lateral surface (21b) • notches (23) between each tooth (21, 21'), • a bottom surface (23c) per notch (23) connecting the first lateral surface (21a) of one tooth (21) to the second lateral surface (21b) of the other neighboring tooth (21') forming the notch (23) between them, • a first radial surface (2c) and a second radial surface (2d) formed on either side of the disk (2) delimiting the notches and teeth (21, 21'), - at least one shim (1, 1') mounted in a notch (23), comprising an external surface (the) partially covering the surfaces delimiting the notch (23), the shim (1, 1') comprising: • a base (10) in contact with the bottom surface (23c), • a first lateral branch (12a) and a second branch lateral (12b) connected to each other by the base (10), each of the lateral branches (12a, 12b) being in contact respectively with a part of the first lateral surface (21a) of a tooth delimiting the notch (23) and with a part of the second lateral surface (21b) of the other tooth (21') delimiting the notch (23), • a first axial retaining element (15c, 15ac, 15bc) of the shim (1, 1') against the first radial surface (2c) to retain the shim (1, 1') in the notch (23) in the axial direction of the disc (2) of the moving wheel.

2. Assembly according to the preceding claim, wherein the shim (1, 1') comprises a second axial retaining element (15d, 15ad, 15bd) of the shim (1, 1') abutting against the second radial surface (2d) to retain the shim (1, 1') in the notch (23) in the axial direction of the disc (2) of the movable wheel.

3. Assembly according to the preceding claim, wherein the first axial retaining element (15c) and the second axial retaining element (15d) of the shim (1, 1') extend axially on either side of the base (10) and are each abutted against respectively a central part (20c) of the first radial surface (2c) of the disc (2) and a central part (20d) of the second intermediate radial surface (2d) to retain the shim (1, 1') in the notch (23) in both axial directions of the disc (2) of the movable wheel.

4. Assembly according to any one of claims 1 to 3, wherein the shim (1') further comprises two other axial retaining elements (15ac, 15ad, 15ad, 15bd) per lateral branch (12a, 12b) extending axially on either side of the corresponding lateral branch (12a, 12b), each of the other axial retaining elements (15ac, 15ad, 15ad, 15bd) abutting against respectively a radial tooth portion (215c, 215c') of the first radial surface (2c) of the disc (2) and a radial tooth portion (215d, 215d') of the second radial surface (2d), to retain the shim (1, 1') in the notch (23) in both axial directions of the disc (2) of the movable wheel.

5. Assembly according to claim 2, wherein the first axial retaining element (15ac) and the second axial retaining element (15bd) of the shim (1') each extend axially on either side of the first lateral arm (12a) or the second lateral arm (12b) and each abut against respectively a radial tooth portion (215c, 215c') of the first radial surface (2c) of the disc (2) and a radial tooth portion (215d, 215d') of the second radial surface (2d), to retain the shim (1, 1') in the notch (23) in both axial directions of the disc (2) of the movable wheel.

6. Assembly according to any one of the preceding claims, wherein the shim (1, 1') is compressed in the notch (23) by including its lateral branches (12a, 12b) constrained towards the interior of the shim (1, 1').

7. Assembly according to any one of the preceding claims, wherein the base (10) of the shim (1, 1') comprises on either side a curved portion (10a, 10b) connected each to the corresponding lateral branch (12a, 12b), each curved portion (10a, 10b) being concave on the side of an internal surface (li) of the shim, and in that each lateral branch (12a, 12b) comprises a protective portion (124a, 124b) extending from the curved portion (10a, 10b), in contact with a bearing surface of the corresponding tooth (21, 21').

8. A movable wheel comprising an assembly according to any one of the preceding claims and at least one blade (3), the blade comprising: - an internal platform (39) - an aerodynamic blade extending radially from the internal platform (39), - a blade foot (32) extending radially from the platform (39) opposite the aerodynamic blade, the blade foot (32) being mounted in a notch (23), the blade foot (32) having a bulbous shape comprising a bearing surface opposite the internal surface (11) of the protective portion (124a, 124b) of the shim (1) and an axial surface (32c) extending in an axial plane opposite the platform (39) - a clearance (J1) between the internal surface (11) at the level of the base (10) of the shim (1, 1') and the axial surface (32c) of the foot (32).