EP3298246B1 - Turbine shroud assembly allowing a differential thermal expansion - Google Patents

Description

Background of the invention

A turbine ring assembly includes a plurality of ceramic matrix composite material ring sectors and a ring support structure.

In the case of all-metallic turbine ring assemblies, it is necessary to cool all the elements of the assembly and in particular the turbine ring which is subjected to the hottest flows. This cooling has a significant impact on the performance of the engine since the cooling flow used is taken from the main flow of the engine. In addition, the use of metal for the turbine ring limits the possibilities of increasing the temperature at the turbine level, which would nevertheless improve the performance of aeronautical engines.

In order to try to resolve these problems, it was envisaged to produce turbine ring sectors in ceramic matrix composite material (CMC) in order to avoid the use of a metallic material.

CMC materials have good mechanical properties making them suitable for constituting structural elements and advantageously retain these properties at high temperatures. The use of CMC materials has advantageously made it possible to reduce the cooling flow required during operation and therefore to increase the performance of the turbomachines. In addition, the use of CMC materials advantageously makes it possible to reduce the mass of the turbomachines and to reduce the hot expansion effect encountered with the metal parts.

However, the existing solutions proposed can implement an assembly of a CMC ring sector with metal attachment parts of a ring support structure, these attachment parts being subjected to the hot flow. Consequently, these metal attachment parts undergo hot expansion, which can lead to mechanical stress on the CMC ring sectors and a weakening of the latter.

We also know the documents UK 2,480,766 , EP 1 350 927 And US 2014/0271145 which disclose turbine ring assemblies.

There is a need to improve existing turbine ring assemblies using a CMC material in order to reduce the intensity of the mechanical stresses to which the CMC ring sectors are subjected during operation.

Object and summary of the invention

To this end, the invention proposes, according to a first aspect, a turbine ring assembly according to claim 1.

The radial direction corresponds to the direction along a radius of the turbine ring (straight line connecting the center of the turbine ring to its periphery). The axial direction corresponds to the direction along the axis of revolution of the turbine ring as well as to the direction of flow of the gas flow in the vein.

The implementation of such inclined portions at the level of the annular flanges of the ring support structure advantageously makes it possible to compensate for the differences in expansion between the annular flanges and the attachment parts of the ring sectors and therefore to reduce the stresses. mechanical stresses to which the ring sectors are subjected during operation.

Preferably, at least one of the flanges of the ring support structure is elastically deformable. This advantageously makes it possible to even better compensate for the differential expansions between the attachment parts of the CMC ring sectors and the flanges of the metal ring support structure without significantly increasing the stress exerted "cold" by the flanges on the hooking parts of the ring sectors. In particular, the two flanges of the ring support structure are elastically deformable or only one of the two flanges of the ring support structure is elastically deformable.

Each of the annular flanges of the ring support structure has a first and a second inclined portions bearing on the attachment parts of the ring sectors, said first and second inclined portions each forming, when observed in meridian section, a non-zero angle with respect to the radial direction and the axial direction. The first inclined portion rests on the upper half of the attachment parts of the ring sectors and the second inclined portion rests on the lower half of the attachment parts of the ring sectors.

The upper half of a hooking part of a ring sector corresponds to the portion of said hooking part extending radially between the zone at mid-length of the hooking part and the end of the hooking part located on the side of the ring support structure. The lower half of a hooking part of a ring sector corresponds to the portion of the hooking part extending radially between the zone at mid-length of the hooking part and the end of the hooking part located on the side of the annular base.

The patent further describes an example outside the invention in which the ring support structure can have axial portions bearing on the attachment parts of the ring sectors, the axial portions each being able to extend parallel to the axial direction , these axial portions can be formed by the annular flanges or by a plurality of added elements engaged without cold play through the annular flanges. According to this example, the attachment parts of the ring sectors can be held to the ring support structure at such axial portions.

In an exemplary embodiment, the annular flanges of the ring support structure can grip the hooking parts of the ring sectors over at least half the length of said hooking parts.

In an exemplary embodiment, the annular flanges of the ring support structure can grip the hooking parts of the ring sectors at least at the level of the external radial ends of said hooking parts. The external radial end of a hooking part corresponds to the end of this hooking part located on the side opposite the flow path of the gas flow. In particular, the annular flanges of the ring support structure can grip the hooking parts of the ring sectors only at the level of the upper half of said hooking parts.

In an exemplary embodiment, the hooking part of each ring sector can be in the form of tabs extending radially. In particular, the external radial ends of the tabs of the ring sectors may not be in contact and the tabs of the ring sectors may define between them an interior ventilation volume for each of the ring sectors.

In an exemplary embodiment, the hooking portion of each of the ring sectors is in the form of a bulb.

In an exemplary embodiment, the ring sectors have a section substantially in the shape of Ω or substantially in the shape of π.

The present invention also relates to a turbomachine comprising a turbine ring assembly as described above.

The turbine ring assembly may be part of a gas turbine of an aeronautical engine or may alternatively be part of an industrial turbine.

Brief description of the drawings

• la figure 1 est une vue en coupe méridienne montrant un mode de réalisation d'un ensemble d'anneau de turbine selon l'invention,
• la figure 2 représente un détail de la figure 1,
• la figure 3 est une vue en coupe méridienne montrant une variante de réalisation d'ensemble d'anneau de turbine selon l'invention,
• les figures 4 à 6 sont des vues en coupe méridienne montrant des réalisations d'ensembles d'anneau de turbine hors invention,
• la figure 7 représente le flasque mis en oeuvre dans la réalisation de la figure 6,
• les figures 8 à 10 illustrent le montage des secteurs d'anneau dans le cas de la réalisation de la figure 5, et
• les figures 11 à 15 illustrent le montage des secteurs d'anneau dans le cas de la réalisation de la figure 6.

Other characteristics and advantages of the invention will emerge from the following description of particular embodiments of the invention, given by way of non-limiting examples, with reference to the appended drawings, in which:

• there figure 1 is a meridian sectional view showing an embodiment of a turbine ring assembly according to the invention,
• there figure 2 represents a detail of the figure 1 ,
• there Figure 3 is a meridian sectional view showing an alternative embodiment of a turbine ring assembly according to the invention,
• THE figures 4 to 6 are views in meridian section showing embodiments of turbine ring assemblies outside the invention,
• there Figure 7 represents the flange used in the production of the Figure 6 ,
• THE figures 8 to 10 illustrate the assembly of the ring sectors in the case of making the Figure 5 , And
• THE figures 11 to 15 illustrate the assembly of the ring sectors in the case of making the Figure 6 .

Detailed description of embodiments

In the following, the terms “upstream” and “downstream” are used here in reference to the direction of flow of the gas flow in the turbine (see arrow F in section figure 1 , For example).

There figure 1 shows a turbine ring sector 1 and a casing 2 made of metallic material constituting ring support structure. The ring support structure 2 is made of a metallic material such as Waspaloy ^® alloy or Inconel ^® 718 alloy.

The set of ring sectors 1 is mounted on the casing 2 so as to form a turbine ring which surrounds a set of rotating blades 3. The arrow F represents the direction of flow of the gas flow in the turbine. The ring sectors 1 are in one piece and made of CMC. The use of a CMC material to produce the ring sectors 1 is advantageous in order to reduce the ventilation requirements of the ring. The ring sectors 1 have, in the example illustrated, a substantially Ω-shaped section with an annular base 5 whose radially internal face 6 coated with a layer 7 of abradable material defines the flow path of the gas flow in the turbine. The annular base 5 also has a radially external face 8 from which a hooking portion 9 extends. In the example illustrated, the hooking portion 9 is in the form of a solid bulb, we do not depart from the scope of the invention when the hooking portion is in the form of a hollow bulb or when the latter is in another form as detailed below. Inter-sector sealing is ensured by sealing tabs (not shown) housed in facing grooves in the facing edges of two neighboring ring sectors.

Each ring sector 1 described above is made of CMC by forming a fibrous preform having a shape close to that of the ring sector and densification of the ring sector by a ceramic matrix. To produce the fibrous preform, ceramic fiber yarns can be used, for example SiC fiber yarns such as those marketed by the Japanese company Nippon Carbon under the name "Nicalon", or carbon fiber yarns. The fibrous preform is advantageously produced by three-dimensional weaving, or multilayer weaving. The weaving can be interlock type. Others Three-dimensional or multi-layer weave weaves can be used, for example multi-canvas or multi-satin weaves. For this, we can refer to the document WO 2006/136755 . After weaving, the blank can be shaped to obtain a ring sector preform which is then consolidated and densified by a ceramic matrix, the densification being able to be carried out in particular by chemical infiltration in the gas phase (CVI) which is well known. in itself. A detailed example of manufacturing CMC ring sectors is described in particular in the document US 2012/0027572 .

The casing 2 comprises two annular radial flanges 11a and 11b made of metallic material extending radially towards a flow path of the gas flow. The annular flanges 11a and 11b of the casing 2 axially enclose the attachment parts 9 of the ring sectors 1. Thus, as illustrated in figure 1 , the hooking parts 9 of the ring sectors 1 are held between the annular flanges 11a and 11b, the hooking parts 9 being housed between the annular flanges 11a and 11b. Furthermore, conventionally, ventilation holes 34 formed in the flange 11a make it possible to bring cooling air to the exterior side of the turbine ring 1.

The annular flanges 11a and 11b each have two inclined portions bearing on the hooking parts 9 of the ring sectors 1 and ensuring their maintenance. The inclined portions of the annular flanges 11a and 11b are in contact with the attachment parts 9 of the ring sectors 1. The upstream annular flange 11a has a first inclined portion 12a as well as a second inclined portion 13a. The flange 11a furthermore has a third portion 15a extending in the radial direction R and located between the first 12a and the second inclined portion 13a. The downstream annular flange 11b also has a first inclined portion 12b as well as a second inclined portion 13b. The flange 11b also has a third portion 15b extending in the radial direction R and located between the first 12b and the second inclined portion 13b. When observed in meridian section and as illustrated in figures 1 and 2 , the first inclined portion 12a of the upstream annular flange 11a forms a non-zero angle α ₁ with the radial direction R and forms a non-zero angle α ₂ with the axial direction A. Likewise, when observed in meridian section, the second inclined portion 13a of the flange upstream annular flange 11a forms a non-zero angle α ₃ with the radial direction R and forms a non-zero angle α ₄ with the axial direction A. The same is true for the first and second inclined portions 12b and 13b of the downstream annular flange 11b . The first and second inclined portions 12a and 13a extend in non-parallel directions (they form a non-zero angle between them). It is the same for the first and second inclined portions 12b and 13b. As illustrated, the inclined portions of the annular flanges 11a and 11b extend forming a non-zero angle with the radial direction R and a non-zero angle with the axial direction A. In the example illustrated, the inclined portions of the annular flanges 11a and 11b each extend in a straight line. In the example illustrated, the inclined portions 12a, 12b, 13a and 13b each have an elongated shape. When observed in meridian section, all or part of the inclined portions of the annular flanges 11a and 11b can form an angle of between 30° and 60° with the radial direction. For each of the annular flanges 11a and 11b, the angle formed between its first inclined portion and the radial direction may or may not be equal to the angle formed between its second inclined portion and the radial direction, when the first and second inclined portions are observed in meridian section.

In the example illustrated, the annular flanges 11a and 11b enclose the attachment parts 9 of the ring sectors over more than half of the length l of said attachment parts 9, in particular over at least 75% of this length. The length l is measured in the radial direction R.

In the example illustrated in figure 1 , the first inclined portions 12a and 12b are, when observed in meridian section, each resting on the upper half M ₁ of the attachment parts 9 and the second inclined portions 13a and 13b are, when observed in meridian section, each resting on the lower half M ₂ of the hooking parts 9. The upper half M ₁ corresponds to the portion of the hooking part 9 extending radially between the zone Z at mid-length of the hooking part 9 and the end E ₁ of the hooking part located on the side of the ring support structure 2 (external radial end). The lower half M ₂ corresponds to the portion of the hooking part 9 extending radially between the zone Z at mid-length of the hooking part 9 and the end E ₂ of the part hooking located on the side of the annular base 5 (internal radial end). The inclined portions of the annular flanges 11a and 11b define two hooks between which the hooking portions 9 of the ring sectors 1 are gripped axially. Each of these hooks has, in the example illustrated, substantially a C shape.

The patent describes below the case where each of the annular flanges has an inclined portion bearing on the attachment parts of the ring sectors.

As mentioned above, the implementation of the inclined portions advantageously makes it possible to compensate for the differences in expansion between the annular flanges 11a and 11b, on the one hand, and the ring sectors 1, on the other hand, and thus to reduce the mechanical stresses to which the ring sectors 1 are subjected during operation.

In the achievements of figures 1 to 5 , at least one of the annular flanges (flange 11b at the figure 1 ) is, as illustrated, provided on its external face with a hook 25 whose function will be detailed below.

In the example illustrated in figure 1 , according to the invention, the retention of the ring sectors 1 to the ring support structure 2 is only ensured by the annular flanges 11a and 11b (no presence of an added element such as a pin through the hooking part 9 of the ring sectors). As will be detailed below, certain embodiments of the invention can use such added elements in order to participate in maintaining the ring sectors on the ring support structure.

We represented at the Figure 3 an alternative embodiment of a turbine ring assembly according to the invention. In this example, the attachment part of the ring sectors 1a is in the form of tabs 9a and 9b extending radially from the external face 8 of the annular base 5. In this example, the external radial ends 10a and 10b of the tabs 9a and 9b of the ring sectors 1a are not in contact. The external radial end of a tab of a ring sector corresponds to the end of said tab located on the side opposite to the flow path of the gas flow. The external radial ends 10a and 10b are, in the example illustrated in Figure 3 , spaced along the axial direction A. The legs 9a and 9b of the ring sectors define between them an interior ventilation volume V for each of the ring sectors 1a. It is thus possible to ventilate the ring sectors 1a by sending cooling air towards their annular base 5 through the ventilation orifice 14 defined between the legs 9a and 9b.

The ring sectors 1a of the Figure 3 substantially have an open Ω shape at its end located on the side of the ring support structure 2.

The fibrous preform intended to form the ring sector 1a of the type illustrated in Figure 3 can be produced by three-dimensional weaving, or multilayer weaving with the provision of unbinding zones making it possible to separate the preform parts corresponding to the legs 9a and 9b from the preform part corresponding to the base 5. Alternatively, the preform parts corresponding to the legs can be made by weaving layers of wires crossing the preform part corresponding to the base 5.

We represented at the figure 4 an example outside the invention in which the ring sectors 1b are held to the ring support structure 2 via annular flanges 21a and 21b each having, as illustrated, an axial portion 16a or 16b extending parallel to the axial direction A. In addition, each of the annular flanges 21a and 21b has a single inclined portion 13a or 13b bearing on the lugs 19a or 19b of the ring sectors 1b and forming a non-zero angle with respect to the radial direction R and in the axial direction A. The axial portions 16a and 16b bear on the lugs 19a and 19b of the ring sectors. The tabs 19a and 19b forming the attachment part of the ring sectors 1b are held to the ring support structure 2 at the level of the axial portions 16a and 16b. The axial portions 16a and 16b formed by the annular flanges block the movement of the ring sectors 1b outwards in the radial direction R. The annular flanges 21a and 21b axially enclose the lugs 19a and 19b of the ring sectors 1b at level of their external radial end 20a and 20b. In the example illustrated, the inclined portion and the axial portion form for each of the annular flanges 21a and 21b a hook bearing on the lugs 19a and 19b of the ring sectors 1b. The tabs 19a and 19b of the ring sectors 1b are clamped axially between these two hooks formed by the annular flanges 21a and 21b. In the achievement illustrated in Figure 4 , the ring sectors 1b have a substantially π-shaped section.

The achievements which will be described illustrated in figures 5 and 6 concern the case where an added element is present through the hooking part of the ring sectors in order to hold the latter. As explained above, the presence of such an added element is optional in the context of the present invention. We represented at the figure 5 an embodiment outside the invention in which the ring sectors 1c are held by blocking pins 35 and 37. More precisely and as illustrated in the figure 5 , pins 35 are engaged both in the annular upstream radial flange 31a of the ring support structure 2 and in the upstream tabs 29a of the ring sectors 1c. For this purpose, the pins 35 each pass through respectively an orifice made in the annular upstream radial flange 31a and an orifice made in each upstream tab 29a, the orifices of the flange 31a and of the tabs 29a being aligned during the assembly of the ring sectors 1c on the ring support structure 2. Likewise, pins 37 are engaged both in the annular downstream radial flange 31b of the ring support structure 2 and in the downstream tabs 29b of the ring sectors 1c . For this purpose, the pins 37 each pass through respectively an orifice made in the annular downstream radial flange 31b and an orifice made in each downstream tab 29b, the orifices of the flange 31b and of the tabs 29b being aligned during the assembly of the ring sectors 1c on the ring support structure 2. The pins 35 and 37 are engaged without cold play through the flanges 31a and 31b and the tabs 29a and 29b. The pins 35 and 37 make it possible to block the ring sectors 1c from rotating. The pins 35 and 37 block the movement of the ring sectors 1c inwards and outwards in the radial direction R. The annular flanges 31a and 31b each also have a single inclined portion 13a or 13b making it possible to reduce the stress applied to the ring sectors 1c during the expansion of the annular flanges 31a and 31b during operation.

We represented at the Figure 6 an embodiment outside the invention in which each sector of ring 1c has a substantially π-shaped section with an annular base 5 whose internal face coated with a layer 7 of abradable material defines the flow path of gas flow in the turbine. Upstream and downstream tabs 29a and 29b extend from the external face of the annular base 5 in the radial direction R.

The ring support structure 2 is, in this embodiment, formed of two parts, namely a first part corresponding to an annular upstream radial flange 31a which is preferably formed integrally with a turbine casing and a second part corresponding to a annular retention flange 50 mounted on the turbine casing. The annular upstream radial flange 31a comprises an inclined portion 13a as described above resting on the upstream lugs 29a of the ring sectors 1c. On the downstream side, the flange 50 comprises an annular web 57 which forms an annular downstream radial flange 54 comprising an inclined portion 13b as described above resting on the downstream lugs 29b of the ring sectors 1c. The flange 50 comprises an annular body 51 extending axially and comprising, on the upstream side, the annular web 57 and, on the downstream side, a first series of teeth 52 distributed circumferentially on the flange 50 and spaced from each other by of the first passages of engagement 53 ( Figure 7 ). The turbine casing comprises on the downstream side a second series of teeth 60 extending radially from the internal surface 38a of the shroud 38 of the turbine casing. The teeth 60 are distributed circumferentially on the internal surface 38a of the ferrule 38 and spaced from each other by second engagement passages 61 ( Figure 13 ). The teeth 52 and 60 cooperate with each other to form a circumferential clutch.

The tabs 29a and 29b of each ring sector 1c are mounted in pre-tension between the annular flanges 31a and 54 so that the flanges exert, at least “cold”, that is to say at ambient temperature of approximately 25°C, a stress on the legs 29a and 29b. Furthermore, as in the realization of the figure 5 , the ring sectors 1c are also held by blocking pins 35 and 37.

At least one of the flanges of the ring support structure is elastically deformable, which makes it possible to even better compensate for the differential expansions between the tabs of the CMC ring sectors and the flanges of the metal ring support structure without significantly increasing the stress exerted “cold” by the flanges on the lugs of the ring sectors.

In addition, the seal between the upstream and downstream of the turbine ring assembly is ensured by an annular boss 70 extending radially from the internal surface 38a of the shroud 38 of the turbine casing and of which the the free end in contact with the surface of the body 51 of the flange 50.

Two mounting methods that can be used to mount the ring sectors on the ring support structure will now be described.

THE figures 8 to 10 which will be described illustrate the assembly of the ring sectors in the case of producing the figure 5 . As illustrated on the figure 8 , the spacing E between the annular upstream radial flange 31a and the annular downstream radial flange 31b at “rest”, that is to say when no ring sector is mounted between the flanges, is less than the distance D present between the external faces 29c and 29d of the upstream and downstream legs 29a and 29b of the ring sectors. The spacing E is measured between the ends of the inclined portions 13a and 13b of the annular flanges 31a and 31b.

The ring support structure comprises at least one annular flange which is elastically deformable in the axial direction A of the ring. In the present example, the annular downstream radial flange 31b is elastically deformable. When mounting a ring sector 1c, the annular downstream radial flange 31b is pulled in the axial direction A as shown on the figures 9 And 10 in order to increase the spacing between the flanges 31a and 31b and allow the insertion of the tabs 29a and 29b between the flanges 31a and 31b without risk of damage. Once the tabs 29a and 29b of a ring sector 1c inserted between the flanges 31a and 31b and positioned so as to align the orifices 35a and 35b, on the one hand, and 37a and 37b on the other hand, the flange 31b is released in order to maintain the ring sector. In order to facilitate the spacing by traction of the annular downstream radial flange 31b, the latter comprises a plurality of hooks 25 distributed on its face 31c, face which is opposite to the face 31d of the flange 31b facing the downstream lugs 29b of the ring sectors 1c. The traction in the axial direction A of the ring exerted on the elastically deformable flange 31b is here carried out by means of a tool 250 comprising at least one arm 251 whose end comprises a hook 252 which is engaged in the hook 25 present on the external face 31c of the flange 31b.

The number of hooks 25 distributed on the face 31c of the flange 31b is defined according to the number of traction points that we wish to have on the flange 31b. This number mainly depends on the elastic nature of the flange. Other shapes and arrangements of means making it possible to exert traction in the axial direction A on one of the flanges of the ring support structure can of course be envisaged.

Once the ring sector 1c inserted and positioned between the flanges 31a and 31b, pins 35 are engaged in the aligned orifices 35b and 35a provided respectively in the annular upstream radial flange 31a and in the upstream tab 29a, and pins 37 are engaged in the aligned orifices 37b and 37a provided respectively in the annular downstream radial flange 31b and in the downstream tab 29b. Each ring sector tab 29a or 29b may include one or more orifices for the passage of a blocking pin.

An analogous method can be used to mount the ring sectors in the context of the examples illustrated in figures 1 , 3 and 4 with the exception that no blocking pawn is used in this case.

We will now describe the assembly of the ring sectors 1c in the case of producing the Figure 6 . As illustrated on the Figure 11 , the ring sectors 1c are first fixed by their upstream tab 29a to the annular upstream radial flange 31a of the ring support structure 2 by pins 35 which are engaged in the aligned orifices 35b and 35a provided respectively in the annular upstream radial flange 31a and in the upstream tab 29a.

Once all the ring sectors 1c are thus fixed to the annular upstream radial flange 31a, we proceed to the assembly by interconnection of the annular retention flange 50 between the turbine casing and the downstream lugs of the ring sectors 29b. In accordance with the embodiment described here, the spacing E' between the annular downstream radial flange 54 formed by the annular web 57 of the flange 50 and the external surface 52a of the teeth 52 of said flange is greater than the distance D' present between the external face 29d of the downstream tabs 29b of the ring sectors and the internal face 60a of the teeth 60 present on the turbine casing. By defining a spacing E' between the annular downstream radial flange and the external surface of the teeth of the flange greater than the distance Between the external face of the downstream tabs of the ring sectors and the internal face of the teeth present on the turbine casing, it is possible to mount the ring sectors prestressed between the flanges of the structure ring support.

The ring support structure comprises at least one annular flange which is elastically deformable in the axial direction A of the ring. In the example described here, it is the annular downstream radial flange 54 present on the flange 50 which is elastically deformable. Indeed, the annular web 57 forming the annular downstream radial flange 54 of the ring support structure 2 has a reduced thickness compared to the annular upstream radial flange 31a, which gives it a certain elasticity.

As illustrated on the figures 14 and 15 , the flange 50 is mounted on the turbine casing by placing the teeth 52 present on the flange 50 opposite the engagement passages 61 provided on the turbine casing, the teeth 60 present on said turbine casing being also placed opposite the engagement passages 53 provided between the teeth 52 on the flange 50. The spacing E' being greater than the distance D', it is necessary to apply an axial force on the flange 50 in the direction indicated on the Figure 14 in order to engage the teeth 52 beyond the teeth 60 and allow rotation R' of the flange at an angle corresponding substantially to the width of the teeth 60 and 52. After this rotation, the flange 50 is released, the latter then being held in axial stress between the downstream tabs 29b of the ring sectors and the internal surface 60a of the teeth 60 of the turbine casing.

Once the flange is thus in place, pins 37 are engaged in the aligned orifices 56 and 37a provided respectively in the annular downstream radial flange 54 and in the downstream tab 29b. Each ring sector tab 29a or 29b may include one or more orifices for the passage of a blocking pin.

The expression “between ... and ...” or “ranging from ... to ...” must be understood as including the limits.

Claims (8)

1. A turbine ring assembly comprising both a plurality of ring sectors (1; 1a) made of ceramic matrix composite material forming a turbine ring, and also a ring support structure (2), each ring sector (1; 1a) having a portion forming an annular base (5) with an inner face (6) defining the inside space of the turbine ring and an outer face (8) from which an attachment portion (9; 9a; 9b) of the ring sector extends for attaching it to the ring support structure, the ring support structure (2) comprising two annular flanges (11a; 11b) between which the attachment portion of each ring sector is held, each of the annular flanges (11a; 11b) of the ring support structure (2) presenting first (12a; 12b) and second (13a; 13b) sloping portions bearing against the attachment portions (9; 9a; 9b) of the ring sectors (1; 1a) and extending along non parallel directions, each of said first and second sloping portions (12a; 12b; 13a; 13b), when observed in meridian section, forming a non-zero angle relative to the radial direction (R) and relative to the axial direction (A),
   the assembly being characterized in that the first sloping portion bears against the upper halves (M₁) of the attachment portions of the ring sectors, and wherein the second sloping portion bears against the lower halves (M₂) of the attachment portions of the ring sectors.
2. An assembly according to claim 1, wherein the annular flanges (11a; 11b) of the ring support structure (2) grip the attachment portions (9) of the ring sectors (1) over at least half of the length ℓ of said attachment portions (9) .
3. An assembly according to claim 1 or 2, wherein the annular flanges (21a; 21b) of the ring support structure (2) grip the attachment portions (19a; 19b) of the ring sectors (1b) at least at the radially outer ends (20a; 20b) of said attachment portions (19a; 19b).
4. An assembly according to any one of claims 1 to 3, wherein the attachment portion of each ring sector is in the form of tabs (9a; 9b; 19a; 19b; 29a; 29b) extending radially.
5. An assembly according to claim 4, wherein the radially outer ends (10a; 10b; 20a; 20b) of the ring sector tabs do not come into contact and wherein the tabs of the ring sectors define between them an internal ventilation volume (V) for each of the ring sectors.
6. An assembly according to any one of claims 1 to 3, wherein the attachment portion of each of the ring sectors is in the from of a bulb (9).
7. An assembly according to any one of claims 1 to 6, wherein the ring sectors are of a section that is substantially Ω-shaped or substantially π-shaped.
8. A turbine engine including a turbine ring assembly according to any one of claims 1 to 7.

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