Device for supporting a turbine ring, turbine having such a device, and turbine engine having such a turbine

[0001] The invention relates to the field of gas turbines, more specifically turbine rings and cantilever devices thereof.

[0002] Generally, a turbine engine of an aircraft, such as an airplane or helicopter, has a top down view in a gas flow direction, a blower, one or more compression stages, for example, a low pressure compressor and a high pressure compressor, a combustion chamber, one or more turbine stages, for example, a high pressure turbine and a low pressure turbine, and a gas exhaust nozzle. Each compressor may be fitted with a turbine, both connected by means of a shaft, thus forming, for example, a high-pressure body and a low-pressure body; wherein in another configuration, the turbine engine may comprise a first turbine connected to a compressor and a second turbine, a so-called free turbine, which is connected to a propeller shaft, for example, a helicopter rotor (the first turbine, connected to the compressor is then usually called a diesel turbine ).

[0003] Hereinafter, the term "diesel" will be abbreviated to "HP" and the expression "low pressure" to the abbreviation "BP".

[0004] The HP turbine is located at the outlet of the combustion chamber. It comprises one or more blade members, each member generally comprising, in known manner, a wheel of fixed blades, called an HP distributor, and a wheel of movable blades. The wheel of the moving blades is set in a rotational motion around the axis of the turbine engine through the stream of exhaust gases of the combustion chamber and rotates together with the HP shaft of the turbine engine, which in turn is rigidly connected with the wheels of the moving blades of the HP compressor. The gas stream in the wheel of the HP turbine moving blades is limited from the outside by a casing in the form of a ring, extending around the periphery of the moving blades, and usually determined by the expression "turbine ring"; this ring may be a monoblock or may be cut into ring sectors; in the following, unless specifically stated, the term "ring" will cover both of these possibilities, that is, either a monoblock ring or a ring cut into ring sectors. The ring is supported by an element called the ring support and is connected to the fixed structure of the turbine engine.

[0005] To allow the movable vanes to rotate, a clearance is left between the radial tips of the movable vanes and the fixed turbine ring that extends opposite the radial tips of the vanes. The greater the clearance, the lower the efficiency (or performance) of the HP turbine, and thus the turbine engine, because part of the gas stream leaving the combustion chamber flows to this clearance, without participating in turning the wheel of the movable turbine blades in rotation.

[0006] The HP turbine zone is exposed to high heat loads, in particular because of its location behind the combustion chamber. Parts of this zone are subjected to at least four separate thermal stresses:

- thermal convection of the cooling gas stream from the compressor;

- thermal conductivity, as a result of which heat is transferred from the gas stream by contacting elements;

- thermal radiation from hot parts of the turbine engine, in particular the combustion chamber and the gas stream in the HP turbine, and - large heat convection flowing in the gas stream conduit, which can be further enhanced when part of the gas stream escapes from the conduit and penetrates from the outside of the ring, at the junction of the turbine ring and its support (it is said then to reabsorb gas or bypass the gas stream, which causes thermal disruption to the turbine ring, as well as a decrease in engine efficiency, because part of the main gas stream does not flow normally, but bypass).

[0007] These different thermal loads entail varied expansion between the various related components they affect, and temperature gradients within static parts that are difficult to control. In particular, creating a model of the effects associated with thermal convection caused by the re-absorption of gases from outside the duct is complicated. This phenomenon is all the more important because the evolution of engine power, related to the goal of reducing fuel consumption, causes an increase in the temperature of gases leaving the combustion chamber in current turbine engines.

[0008] It has been proposed that the clearance between the blade tips and the turbine ring be adjusted by various means. For example, the patent document EP 1,475,516 proposes a structural casing (on which the ring support element is mounted) having some flexibility, its shape depends therefore on the pressure it is subjected to at different engine speeds, which allows adjusting the clearance at the tips of the blades.

[0009] US 2005/0232752 also discloses a turbine ring support device according to prior art.

[0010] The present invention aims to propose a turbine ring cantilever device that allows better control of backlash at the tips of the turbine blades and better resistance of the elements to aging, in order to ensure stability of the properties of the flowing gas in the passage of time.

[0011] To achieve this, the invention relates to a gas turbine ring support device according to claim 1, wherein the ring is intended to enclose movable gas turbine blades flowing from top to bottom, and the device comprises at least one upper hook facing upwards, intended to be placed in the upper groove of the ring, open downwards, and at least one lower hook, turned downwards, intended to be placed in the bottom groove of the ring, open in the upward direction, the device having in front of the upper hook means (e.g. holes) for injecting cooling gas for cooling the top hook and / or has means (e.g. holes) for injection in the bottom hook cooling gas for cooling the bottom hook.

[0012] Thanks to the invention, each of the hooks of the cantilever device is located in the groove of the ring and is thus protected against a gas stream flowing through the ring itself, which guarantees that they will maintain a constant shape regardless of the turbine speed, as the temperature fluctuations exert on the no less impact. In this way, ensuring the integrity of the hooks, we make controlling the play between the tips of the blades and the ring easier and thus improved, because you can better control the progressive changes over time as they change and integrity. Thanks to the cooling gas injection means, the thermal integrity of the upper hook and / or lower hook is even better assured, which further optimizes the transient thermal states.

[0013] According to a preferred embodiment, the cooling gases are at a pressure higher or equal to the pressure of the gaseous stream flowing from the upper side of the movable turbine blades. In this way, the cooling gas also acts as a barrier for possible re-absorption of gases from the gas stream from the top of the ring.

[0014] According to a preferred embodiment, the cooling gas is at a pressure higher or equal to the pressure of the gaseous stream flowing on the bottom side of the movable turbine blades. In this way, the cooling gas also acts as a barrier for possible re-absorption of gases from the gas stream from the bottom of the ring.

According to the invention, the device is arranged to form a pressure cavity fed with cooling gas between the two hooks. The hooks are thus even more protected as the recess protects them from the gas stream from the turbine. In particular, the cavity pressure is higher or equal to the pressure of the gaseous stream flowing from the upper side of the movable turbine blades, which prevents re-absorption of gas from the gaseous stream. The special shape of the ring allows the creation of such a pressure cavity; it is improved by the presence of additional sealants such as those shown below.

[0016] According to a preferred embodiment, the upper groove of the ring has a curved contact surface with the upper hook (in axial section, this is the axis of the ring being the axis of the turbine engine).

[0017] According to a preferred embodiment, the lower groove of the ring has a curved contact surface with the lower hook (in axial section, this is the axis of the ring being the axis of the turbine engine).

[0018] According to a preferred embodiment, the device comprises at least one upper gasket arranged to ensure gas tightness between the ring and the upper hook, the upper gasket being located in the upper groove of the ring. Such a gasket improves the gas tightness of the device, which is particularly advantageous when the pressure cavity is formed between the upper and lower hooks and / or when the upper cooling gases are intended to create a barrier for gases from the gas stream from the turbine, above the upper hook . Such a seal may also participate in keeping the ring in axial and radial position.

[0019] According to a preferred embodiment, the device comprises at least one lower seal arranged to ensure gas tightness between the ring and the lower hook, the lower seal being positioned in the lower groove of the ring. This bottom seal provides the same bottom benefits as the top seal.

[0020] According to a preferred embodiment, the top seal and / or bottom seal is a braided seal type of refractory material. Such a seal additionally improves the sealing efficiency, while preferably participating in keeping the ring in the axial and radial position.

[0021] According to a preferred embodiment, the device comprises, on the upper side of the ring, a peripheral seal, ensuring tightness against gases flowing from the outside of the turbine distributor housing extending above the movable blades.

[0022] According to a preferred embodiment, the device comprises an upper support element having an upper hook and a lower support element separate from the upper support element having a lower hook.

[0023] According to a particular embodiment, in this case the upper and lower cantilever members are monoblocks and are annular, and the ring is divided into at least two annular sectors.

[0024] Preferably, in this case, the upper and lower cantilever members are adapted to be assembled with the ring by sliding the cantilever members on top of each other, by shrink fit, which ensures axial and radial positioning of the ring. This assembly is facilitated by the presence of upper and lower seals as described above, and these seals can participate in keeping the ring in a radial and axial position on its support.

[0025] Always preferably, at least one sealing plate is located on the interface between surfaces in contact with two successive annular sectors in a groove provided for this purpose. According to a particular embodiment, the plate is arranged so as to allow the cooling gas to leak from the pressure cavity formed between the hooks towards the gas stream; such leakage prevents gas flow in the reverse direction (i.e. gas leakage outside the turbine gas stream) and allows cooling gases to be blown.

[0026] According to another particular embodiment, the ring is a monoblock and is annular, the bottom cantilever is a monoblock and is annular, and the upper cantilever is divided into at least two sectors of the cantilever.

According to a particular embodiment, in this case, the minimum radial diameter of the lower hook is greater than the minimum radial diameter of the upper hook. Such a difference in diameter makes it easier to assemble different elements between each other.

[0028] The invention further relates to a gas turbine ring intended to enclose movable turbine blades driven by a gas stream flowing from top to bottom, the ring being intended to be supported by the above-mentioned cantilever device, the ring having an upper groove, open towards pit intended for placing at least one upper hook facing upwards, a cantilever device and a bottom groove, open upwards, and intended to accommodate at least one bottom hook, downwardly facing, cantilever device.

[0029] The invention further relates to a turbine comprising the cantilever device described above.

[0030] The invention further relates to a turbine (or turbojet) engine having such a turbine.

[0031] The invention will be better understood by the following description of a preferred embodiment of the invention, with reference to the attached sheets with drawings in which:

- Fig. 1 is a schematic cross-sectional view of the turbine ring and its cantilever device according to a first preferred embodiment of the invention;

- Fig. 2 is a detailed schematic view of the ring and cantilever device of Fig. 1 showing the cooling gas flow;

- Fig. 3 is a schematic cross-sectional view of the turbine ring and its cantilever device according to a second preferred embodiment of the invention;

- Figs. 4a to 4c are schematic representations of the different stages of mounting the ring and support device of Fig. 3.

[0032] Referring to Fig. 1, a turbine engine, intended, for example, for use in an airplane or helicopter, has, viewed from top to bottom in the direction of gas flow, a blower, a BP compressor, an HP compressor, a combustion chamber, HP 1 turbine, BP turbine and gas exhaust nozzle. The BP turbine is connected to the BP compressor by means of the BP shaft, forming the BP member, while the HP turbine is connected to the HP compressor by means of the HP shaft, forming the HP member.

[0033] The invention will be illustrated in various examples thereof in Figures 1 and 2, on the one hand, and from 3 to 4c, on the other hand, with reference to the HP turbine 1 of the turbine engine of the type described above. Of course, the invention applies to any turbine subjected to thermal stress, in particular to the turbine of a helicopter turbine engine having an HP turbine connected to an HP compressor and a free turbine connected to the shaft driving the helicopter rotor (the invention is therefore preferably used for HP turbines, but also for free turbine). The invention can be applied to other types of turbines.

[0034] The HP turbine 1 has a wheel of fixed blades 2, called an HP distributor, and a wheel of movable blades 3, set in rotation by a gas stream G, which flows out of the combustion chamber and flows from top to bottom. The movable blades 3 rotate around the axis A, which is the axis of the turbine engine.

[0035] The terms inside (or internal) and outside (or external) are defined with reference to the A axis of the turbine engine, it being understood that situated or directed towards the inside (or inward) is what is located on or directed towards the A axis of the turbine engine. In addition, radial and longitudinal concepts are defined with reference to the A axis of a turbine engine, while the upper and lower concepts - with reference to the direction of gas flow.

[0036] In a known manner, the gas stream in the HP 1 turbine is limited from the outside by an annular housing 4 (usually referred to by the experts as "external meridian") on which fixed blades 2 of the distributor are mounted, and by a ring 5, called a turbine ring 5, which is mounted below the housing 4 and forms a housing covering the movable blades 3.

[0037] The turbine ring 5 has an overall annular shape around its entire circumference, i.e. 360 °. In the embodiment of Figures 1 and 2, it is cut into a plurality of annular sectors 5 (in this case ten sectors) which, when juxtaposed with each other, form the ring 5 as a whole; in this case, there is talk about ring 5 divided into sectors.

[0038] In the following description of the embodiment of Figures 1 and 2, the form of the annular sector 5 is described, it being understood that the ring 5 is axially symmetrical (it is a rotational part); in order to simplify the presentation, it is thus combined into one concept of ring 5 and ring sector 5. In other words, the features presented for the ring design apply to the ring in the form of a monoblock as well as to the ring divided into ring sectors, it being understood that the ring sector is ultimately only a part of the ring having the same shape as the entire ring, but being its sector, i.e. having a smaller circumferential extent.

[0039] Ring 5 has an inner wall 6 defining the outer limit of the gas stream; the radial tips of the blades 3 extend at a distance e from this wall 6, this distance corresponding to the clearance e between the tips of the blades 3 and the ring 4, the possibility of the best adjustment and control which is desirable over time. The ring 5 further has an upper edge 7 defining an upper groove 8 and a lower edge 9 defining a lower groove 10.

[0040] The upper groove 8 is open downwards; for this purpose, the upper edge 7 has a radial wall 7a extending outwards from the inner wall 6 of the ring 5 and a longitudinal wall 7b extending downwards from the outer end of the radial wall 7a (in this case perpendicular to her).

[0041] The lower groove 10 is open up; for this purpose the bottom edge 9 has a radial wall 9a extending outwardly from the inner wall 6 of the ring 5 and a longitudinal wall 9b extending upwards from the outer end of the radial wall 9a (in this case perpendicular to it) .

[0042] The turbine engine has a cantilever device 11 of the ring 5. This device 11 has an upper hook 12, facing upwards, placed in the upper groove 8 of the ring 5, and a lower hook 13, facing downwards, located in the lower groove 10 of the ring 5; the ring 5 is therefore supported and held in position by the hooks 12, 13.

[0043] More specifically, the hooks 12, 13 are annular, and in the embodiment of Figures 1 and 2, monoblocks around the entire circumference of the ring 5 (i.e. the perimeter of the ring sector assembly 5).

[0044] In the embodiment shown, the hooks 12, 13 are axially symmetrical. Alternatively, the hooks 12, 13 may be perforated and / or may have a plurality of small hooks arranged around the perimeter.

[0045] The upper hook 12 is supported by the upper support element 14, having an overall cylindrical longitudinal shape (according to the axis A of the turbine engine), which is connected to the fixed structure of the turbine engine in a manner not shown (for example, by means of a mounting flange, bolted complementary flange of a fixed structure). The hook 12 has a radial wall 12a, extending inwardly from the upper support member 14, and a longitudinal wall 12b extending upwards from the inner end of the radial wall 12a (in this case perpendicular to it).

[0046] The lower hook 13 is supported by the lower support element 15, having an overall cylindrical longitudinal shape (according to the axis A of the turbine engine), which is connected to the fixed structure of the turbine engine in a manner not shown (e.g. by means of a mounting flange, bolted complementary flange of a fixed structure). The hook 13 has a radial wall 13a, extending inwardly from the bottom bracket 15, and a longitudinal wall 13b extending downwards from the inner end of the radial wall 13a (in this case perpendicular to it).

[0047] The upper and lower hooks 13 are respectively placed in the upper and lower grooves 8 of the ring 5 to keep them in position and are thus thermally protected by the ring 5 itself, and more precisely by its inner wall 6 and through the walls (7a, 7b), (9a, 9b) forming the edges 7, 9, delimiting the grooves 8, 10 respectively.

[0048] Referring to Fig. 2, the upper groove 8 has a contact surface 8 'with the upper hook 12; in this case, this contact surface 8 'has a curvilinear cross-sectional shape to allow stable positioning of the ring 5 on the upper hook 12, regardless of possible mounting inaccuracies resulting, for example, from manufacturing tolerances.

[0049] The lower groove 10 has a contact surface 10 'with the lower hook 13; in this case, this contact surface 10 'has a curvilinear cross-sectional shape to allow stable positioning of the ring 5 on the lower hook 13, as explained above for the upper hook 12.

[0050] The upper support element 14 has cooling holes 16 for allowing cooling gas (coming, for example, from a compressor) to be injected from the outside of the upper support element 14 towards the upper hook 12, in order to cool the latter (cooling gases also allow cooling the upper edge 7 of the ring 5); this upper cooling gas stream is symbolically represented by the arrow G1 in Fig. 2. The upper hook 12, protected by the ring 5, is therefore cooled, which further improves thermal stability and enables the radial displacement of the axially symmetrical elements of the support device 11 to be controlled, thus facilitating the control of the clearance e between the tips of the blades 3 and the ring 5, especially since the ring 5 is also cooled.

[0051] The lower support 15 has cooling holes 17 to allow injection of cooling gas (originating, for example, from a compressor) from outside the lower support 15 towards the lower hook 13, in order to cool the latter (cooling gases also allow cooling the bottom edge 9 of the ring 5); this lower cooling gas stream is symbolically represented by the arrow G2 in Fig. 2. In this case, the upper and lower 15 cantilever elements partly overlap in the cooling apertures 17, the upper cantilever 14 also has bored holes 18 for cooling gas flow from the lower hook 13. The lower hook 13, protected by the ring 5, is therefore cooled, which further improves thermal stability and allows the radial displacement of the axially symmetrical elements of the support device 11 to be controlled, thus facilitating the control of the clearance e between the tips of the blades 3 and the ring 5, especially since the ring 5 it is also cooled.

[0052] Simultaneous cooling of the upper 12 and lower 13 hooks is particularly advantageous: the ring 5 can thus be supported by means 12, 13, which it protects and further cooled, thus showing very good structural stability, irrespective of thermal fluctuations, associated for example with speed changes.

[0053] The radial walls 12a, 13a of the upper 12 and lower 13 hooks are further adapted in this case to form, together with the longitudinal wall part of the upper support element 14 and with the longitudinal wall part 6 of the ring 5, the pressure chamber C; in Fig. 2 it can be more clearly seen that each of the radial walls 12a, 13a of the hooks 12, 13 is extended at its inner end by a projection 12a ', 13a' in contact with the longitudinal wall 6 of the ring 5; and the contact protrusions 12a ', 13a' are perforated radial walls.

[0054] The pressure cavity C is fed with cooling gases which are injected through the cooling holes 19; this cooling gas stream is symbolically represented by the arrow G3 in Fig. 2. Cooling gases cool the hooks 12, 13, but also the ring 5, and in particular its longitudinal wall 6.

[0055] The perforated annular sheet 20 is in this case mounted from the outside of the upper support element 14 on the pressure cavity C, to cool the upper support element 14 by gas (as symbolically shown by arrows G4), and to adjust G3 cooling gas flow rate supplying pressure chamber C. The gas interaction realized through the use of this plate 20 allows, in combination with the upper stream G1 and the lower stream G2 of cooling gases, thermodynamic monitoring of radial displacements of the axially symmetrical elements of the support device 11, thus allowing optimization of the clearance e between the tips of the blades 3 and the ring 5 .

[0056] The upper O-ring 21 is mounted between the upper end of the upper hook 12 and the surface of the upper groove 8 of the ring 5, from the inside of the latter; it forms, together with the upper contact projection 12a ', the longitudinal wall 6 of the ring 5, and the upper hook 12, a cavity C1. This gasket 21 improves the tightness of the pressure cavity C from the upper side (the cavity C1 is connected to the pressure cavity C by means of the holes of the upper contact projection 12a ').

[0057] The lower O-ring 22 is mounted between the lower end of the lower hook 13 and the surface of the lower groove 10 of the ring 5; from the inside of the latter; together with the lower contact projection 13a ', the longitudinal wall 6 of the ring 5 and the lower hook 13, it forms a cavity C2. This gasket 22 improves the tightness of the pressure cavity C from the bottom side (cavity C2 has a connection with the pressure cavity C via the holes of the lower contact projection 13a ').

[0058] The O-rings 21, 22 are in this case so-called braided gaskets, i.e. each of them is formed of a larger number of strands entwined with each other, in this case the strands are formed of a refractory material retaining its properties mechanical at high temperatures to which the ring 5 is subjected. In the embodiment shown, each of the seals 21, 22 is divided into sectors in a manner corresponding to the sectors of the ring 5; alternatively, each of the seals 21, 22 may extend over the entire circumference of the ring 5, between different sectors of the ring 5.

[0059] The cantilever device 11 of the ring 5 further comprises a "segment" (metal) gasket 23 located on the upper flange 24 of the upper support member 14. The segment gasket 23 contacts the outer surface of the annular distributor housing 4 and makes it gas tight.

[0060] Various elements of the ring 5 and the cantilever device 11, in particular the cooling holes 16, 17, 18, 19 are configured so that the cooling gases G1, G2, G3 also function as a (pressure) barrier for gases from the turbine gas stream G 1, which is to avoid bypassing these gases, i.e. the flow of gases from the gas stream G on the outside of ring 5, in other words the re-absorption of gases from the gas stream G, which would be very harmful to the efficiency of the turbine engine, but also to the integrity of the static components of the cantilever device 11.

[0061] To this end, the ring 5 and the support device 11 are configured so that the gas pressure upstream of the upper hook 12, and more specifically in the cavity C3, defined between the support flange 24 of the segment seal 23 and the upper hook 12, is higher than the gas pressure in gas stream G before blades of 3 turbines; for example, it can be equal to 6 bar, while the gas pressure in the gas stream G before the turbine blades 3 is equal to 5 bar. In this way, the cooling gases G1 tend to leak from the cavity C3 towards the gas stream, using the clearance J between the annular housing 4 of the distributor and the ring 5 than to leak in the opposite direction. The hooks 12, 13 are therefore protected against reabsorption of the gas from above, which avoids being subjected to thermal convection which would be the result of such reabsorption, and thus makes it easier to control the clearance 7 at the tips of the blades 3, as the differential expansion is smaller.

[0062] It should be noted that the gas pressure upstream of the segment gasket 23 is also higher than the gas pressure in the gas stream G upstream of the turbine blades 3, in order to avoid possible gas recurrence in the event of leakage at the segment gasket 23; otherwise, small leakage can be voluntarily provided to provide even better protection for the ring hooks 12, 13 by the cooling gas stream coming from the upper side of the segment seal 23.

[0063] Furthermore, the ring 5 and the support device 11 are configured so that the gas pressure in the cavity C4, located behind the bottom hook 13, is higher than the gas pressure in the gas stream G behind the turbine blades 3; for example, it may be equal to 3 bar, while the gas pressure in the gas stream G behind the turbine blades 3 is equal to 2.5 bar. In this way, cooling gases G1 tend to leak from cavity C3 in the direction of the gas stream (using clearance not shown here) than to leak in the opposite direction. The hooks 12, 13 are therefore protected against reabsorption of the gas from below, which avoids being subjected to thermal convection, which would be the result of such reabsorption, and thus makes it easier to control the clearance 7 at the tips of the blades 3, as the differential expansions are smaller.

[0064] Furthermore, the ring 5 and its support device 11 are configured so that the gas pressure in the pressure cavity C is higher or equal (in this case it is substantially equal) the gas pressure in the gas stream before the turbine blades 3, in order to obtaining a full barrier for gases from gas stream G, created by cavity C3 in front of the upper hook 12.

[0065] In cavities C3, C and C4 there is a pressure higher than the pressure of the gases in the gas stream flowing along them, forming a barrier for these gases; this dam protects the hooks 12, 13 and is therefore particularly advantageous for controlling the clearance e on the tips of the blades 3. In addition, the cooling gases feeding these various chambers C3, C, C4 allow the hooks 12, 13, but also the ring 5 to be cooled.

[0066] As shown in Fig. 2 and in a known manner, the ring sectors 5 further comprise, on the interface surfaces between their contacting tips, sealing plates 25, which plates 25 extend, for example, in cutouts provided on the surface of the tip of one or two touching annular sectors 5. These plates 25 are arranged to ensure maximum tightness between the pressure cavity C and the flowing gas stream G from the turbine and thereby avoid re-absorption of gases from the stream into the pressure cavity C; of course, since the seal cannot be perfect, the device allows the cooling gases to leak from the pressure cavity C into the gas stream G flowing from turbine 1, which allows these cooling gases to be blown. The pressure cavity C, extends in the same vertical as the blades 3 of the turbine (i.e. in the same longitudinal plane as the blades 3), and its pressure is equal to the pressure in front of the blades 3, the pressure in the pressure cavity is therefore higher than pressure at the level of blades 3 (pressure decreases in the turbine from top to bottom); in this way, the gases must be transferred from the pressure cavity C to the gas stream from turbine 1, and not vice versa.

[0067] To further improve thermal protection and reduce the supply of gases to the hooks 12, 13, the ring 5 is in this case covered on the inside of its longitudinal wall 6 with a coating 26 of ceramic material.

[0068] The assembly of the ring 5 on its cantilever device 11 will now be described. It is about assembly by moving the upper and lower 15 cantilever elements relative to each other and by shrink fit. More specifically, the upper support member 14 is heated (for example, to 100 ° C) and moved by sliding in such a way that the upper and lower hooks 13 are close together and even in contact; this is possible because the support elements 14, 15 are telescopic, and the radius of the longitudinal wall of the upper support element 14 is slightly larger than the radius of the longitudinal wall of the lower support element 15. The annular sectors 5 then enter the lower hook 13 (which is located in their lower grooves 10). The upper support element is then moved upwards until it abuts the upper hook 12 in the upper groove 8 of the ring 5; in this position, the upper hook 12 abuts the upper groove surface 8 'of the outer upper corner of its longitudinal wall 12b and the upper braided gasket 21 of the inner upper corner of its longitudinal wall 12b; furthermore, the lower hook 13 abuts against the bottom groove surface 10 'with the outer bottom corner of its longitudinal wall 13b and with the bottom braided seal 22 with the inner bottom corner of its longitudinal wall 13b. In the last stage, the whole assembly is allowed to cool, which creates a tight connection between the various elements, by shrink fit of the upper support element 14 (the radius of its longitudinal wall decreases during cooling) on ​​the lower support element 15, in a way whose general principles are known.

[0069] The segment gasket 23 is mounted later, for example, by gluing, and the gluing agents disappear during operation.

[0070] A second embodiment of the ring and cantilever device will be described with reference to Figs. 3 and 4a to 4c. This embodiment is very similar to the previous embodiment, therefore the reference numerals used in Figs. 3 and 4a to 4c for turbine components of identical design or function, equivalent or similar to those used for turbine components in Figs. 1 and 2 are the same for ease of description. Furthermore, the entire description of the turbine of Figs. 1 and 2 has not been repeated again, this description applies to the turbine of Figs. 1 and 2, as there is no incompatibility. Only remarkable design and functional differences will be described.

[0071] The main difference in the second embodiment is that the ring 5 is a monoblock and thus forms a full ring from one part axially symmetrical, 360 ° (in other words, it is not divided into sectors). In addition, the lower bracket 15 is also a mono-block (360 °), while the upper bracket 14 is divided into sectors, i.e. it is cut into many sectors of the upper bracket 14 (in this case into ten sectors) . [0072] As before, the ring 5 is supported by the upper 12 and lower 13 hooks, placed in the upper and lower grooves 8 of the ring 5, which has the same advantages. Cooling gas injection means (not shown) are provided to cool the hooks 12, 13, but also the ring 5 which controls the clearance e on the tips of the blades; they supply pressure cavities C3, C, C4; in the same way as before, these injection means are arranged so as to allow the cooling gases to fulfill the function of a barrier in relation to the gases from gas stream G of turbine 1, in order to avoid their flow on the outside of the ring 5; to achieve this, the gas pressures on the outside of the ring 5 are higher than the corresponding pressures in the gas stream G of turbine 1.

[0073] In contrast to the embodiment of Figs. 1 and 2, in which the upper and lower grooves 10 have the same dimensions (the radii of their longitudinal walls 7b, 9b are equal), the upper and lower grooves 8 in the embodiment of Figs. . 3 they do not have the same dimensions, the radius of the longitudinal wall 9b of the lower edge 9 forming the lower groove 10 is greater than the radius of the longitudinal wall 7b of the upper edge 7 forming the upper groove 8; the longitudinal wall 6 of the ring 5 is parallel to the axis A of the turbine engine, and the radial dimension of the radial wall 9a of the lower edge 9 forming the lower groove 10 is therefore larger than the radial dimension of the radial wall 7a of the upper edge 7 forming the upper groove 8. The longitudinal wall 13b of the lower hook 13 therefore extends at a greater radial distance from the axis A of the turbine engine than the longitudinal wall 12b of the upper hook 12 (longitudinal walls 12b, 13b of hooks 12, 13 have a support in the upper and lower grooves 8 near the longitudinal walls 7b, 9b of the edges 7, 9, forming these grooves 8, 10). These radius differences allow assembly of the assembly, explained below.

[0074] The assembly of the ring 5 and its support device 11 will now be described in more detail and with reference to Figs. 4a, 4b and 4c. In contrast to the assembly described with reference to Figs. 1 and 2, this is not about assembly by sliding the support elements one over the other and by shrink fit, but about assembly by sliding the support elements against the ring and tightening with screws.

[0075] Referring to Fig. 4a, during the first stage, the lower support element 15 is assembled with the ring 5 by the relative movement of the ring 5 in a downward direction relative to this element 15 (this relative movement is symbolically represented by an arrow F1), thus enabling the lower hook 13 to be positioned in the lower groove 10 of the ring 5.

[0076] Referring to Fig. 4b, during the second stage, the first sector of the upper support element 14 is mounted with the ring 5 by the relative movement of this sector 14 from the outside inwards, then from the bottom up with respect to the assembly formed by the ring 15 and the lower cantilever element (this relative movement is symbolically represented by arrow F2), thus enabling the upper hook 12 to be positioned in the upper groove 8 of the ring 5.

[0077] Referring to Fig. 4c, during the third stage, the spacer 27, not shown in Fig. 3, having an annular shape and corresponding circumferentially to the sector of the upper support element 14, is inserted between the lower flange 14 'of the upper support element 14 and the upper flange 15 'of the lower support element 15 to maintain their distance (movement of the strut 27 is symbolically represented by arrow F3). The upper and lower 15 cantilever elements are thus rigidly fixed to each other by means of screws 28 (whose movement is symbolically represented by arrow F4), placed to fasten the flanges 14 ', 15' of the cantilever elements 14, 15 and strut 27 inserted between them.

[0078] Finally, the second and third steps are repeated for the second sector of the upper support element 14 to complete this upper support element 14 around the entire circumference of the ring 5.

[0079] Thanks to the invention in this embodiment, in particular, the turbine ring 5, being a monoblock with annular hooks 12, 13 completely symmetrical in axis, can be kept in position, in contrast to the state of the art in which the monoblock rings are held by means of arms operating in a punctual or discreet manner. As a result, the deformations experienced by the ring 5 in the form of a monoblock are axially symmetrical, and thus they are simpler to model.