EP0789133A1 - Support disc with stiffening element for the labyrinth seal of a turbo machine rotor - Google Patents

Abstract

The labyrinth seal disc (12) consists of a main rim (13) incorporating labyrinth seals (10). An arched section (14) presses against the forward surface (19) of the rotor disc (8). Fixing bolts (6) are located between the two discs. The seal disc incorporates a main radial stiffener (23) just inside the labyrinth seal. The arched section of the disc is formed in the upper part of the rim (13), is elongated in a radial direction and slightly convex. The rear edge (22) of the disc is on a level with the rear portion of the stiffener. Additional fixings between the two discs are provided by teeth (24) on the back of the seal disc engaging with slots in the rotor disc. The arched section is reinforced by ribs (26) extending from the teeth.

Description

Field of the invention

The invention relates to turbomachines, such as axial flow turbojets using labyrinth sealing devices to separate chambers containing air and / or oil. This is the case, in particular, of the labyrinth fixed upstream of the high pressure turbine.

Prior art and problem posed

Referring to Figure 1, the technological definition of turbomachines, involving air flows at different pressures and temperatures, provides for the use of sealing devices between enclosures containing air and / or l 'oil. This is the case of the labyrinth disk 2 existing upstream of the high pressure turbine 1 and placed on the passage of part of the cold flow at the level of the combustion chamber. This part, as it is placed, undergoes extremely high mechanical forces, due, in particular, to centrifugal force, since it is placed on the rotor. A difficult environment is added to this because the air flow surrounding it is rather oxidizing and the thermal level is very high. One can also add very restrictive vibrational excitation phenomena appearing during the passage in certain speed regimes, where parts of the rotary equipment resonate.

For these reasons, this part, also called the front labyrinth of the high-pressure turbine, is one of the most difficult parts to size. This operation can also sometimes lead to giving it an insufficient lifespan, or a limitation in its thermal qualities.

In FIG. 1, it can be seen that this labyrinth disk 2 has several parts, including the labyrinth itself being largely opposite the arrow referenced 2. The lips of this labyrinth are carried by a rim 3 extending towards the top by a vault 4 which bears on a downstream surface 5 of the disc 8 of the rotor to which this part is fixed. This fixing is carried out, on many current turbojets, by means of bolts 6 passing through the interior part of this part which ends in an interior stiffener 7.

It is added that this fixing by bolting does not promote the increase in the life of the whole of this part.

The object of the invention is to optimize the shape of this part which is the labyrinth disk and its device for fixing to the disk 8 of the rotor of the high pressure turbine.

Summary of the invention

• une jante principale ;
• un labyrinthe incorporé à la jante ;
• une voûte dans le prolongement extérieur de la jante pour prendre appui sur une surface amont du rotor ; et
• des moyens de fixation du disque labyrinthe sur le rotor.

To this end, the main object of the invention is a labyrinth disk for a turbomachine rotor comprising:

• a main rim;
• a labyrinth incorporated into the rim;
• a vault in the outer extension of the rim to bear on an upstream surface of the rotor; and
• means for fixing the labyrinth disk to the rotor.

According to the invention, the labyrinth disc comprises a main stiffener incorporated in the rim, just inside the labyrinth.

In one of the embodiments of the labyrinth disc according to the invention, the arch is an upper part of the rim which is fairly radially elongated, slightly curved, its downstream surface being placed at the axial level of the downstream end of the main stiffener.

In a first embodiment, the fixing means comprise fixing bolts placed in fixing holes made in the inner part of the rim, inside and upstream of the stiffener.

In another embodiment of the invention, the fixing means consist of fixing teeth intended to be placed behind teeth of a bayonet locking system fixed on the rotor. In these cases, the arch can include stiffeners placed in the interior extension of the fixing teeth.

Axial stops can complete the system by coming into abutment opposite the rotor stop surfaces placed on an upstream surface thereof.

The vault of the labyrinth disc according to the invention may include stiffeners placed on the downstream surface of the rim.

Part of the downstream surface of the vault can then act as an axial abutment surface, in particular when the latter has ribs.

The axial stops can also be provided by the inner surface of the fixing teeth.

List of Figures

• figure 1, en demi-coupe longitudinale, une partie d'un turboréacteur de l'art antérieur ;
• figure 2, en demi-coupe, une partie d'un turboréacteur dans lequel est installée l'invention ;
• figure 3, en coupe, une première variante du disque labyrinthe selon l'invention ;
• figure 4, en coupe, une deuxième variante du disque labyrinthe selon l'invention ;
• figure 5, en coupe, une troisième variante du disque labyrinthe selon l'invention ;
• figure 6, en coupe, une quatrième variante du disque labyrinthe selon l'invention ; et
• figure 7, en coupe, une variante des moyens de fixation du disque labyrinthe selon l'invention.

The invention and its various technical characteristics will be better understood on reading the following description accompanied by seven figures representing:

• Figure 1, in longitudinal half-section, part of a turbojet engine of the prior art;
• Figure 2, in half-section, part of a turbojet engine in which the invention is installed;
• Figure 3, in section, a first variant of the labyrinth disk according to the invention;
• Figure 4, in section, a second variant of the labyrinth disk according to the invention;
• Figure 5, in section, a third variant of the labyrinth disk according to the invention;
• Figure 6, in section, a fourth variant of the labyrinth disk according to the invention; and
• Figure 7, in section, a variant of the fixing means of the labyrinth disk according to the invention.

Detailed description of the planned achievements

The labyrinth disk, object of the invention, is placed substantially in the same place as that where the labyrinth disk of FIG. 1 is placed.

It generally comprises a rim 13 which constitutes the radial framework of this part. The inner part of this rim 13 ends with an inner stiffener 9 which is less consistent than that referenced 7 in FIG. 1.

The labyrinth 10 of the labyrinth disc is made up of two parts, each comprising several lips tangent with the friction parts 16 fixed on a fixed part 17 attached to the stator inside and at the outlet of the combustion chamber 20.

In the embodiment shown in Figure 1, it is by the inner part, that is to say by the flange located above the internal bore 9, that the assembly is fixed on the rotor, symbolized by the radial disc 8. The fixing means shown are bolts 6 penetrating into holes in the internal bore 9.

The rim 13 is extended by a central part comprising passages 11 and lower orifices 15 allowing the passage of the cooling air flow from the upstream part to the downstream part of the labyrinth disc.

The outer part of the labyrinth disk 12, according to the invention, is constituted by the arch 14 extending the rim 13 to bear by an outer end 18 on an upstream surface 19 of the rotor. This vault 14 is slightly less rounded than that of FIG. 1.

It is thus understood that the seal is produced between the volume of the turbomachine placed inside the volume delimited by the combustion chambers 20, and the inlet of the high pressure turbine 1, symbolized by a blade 21 of its first stage . However, passages 11 allow the cold flow to pass from the upstream surface of the labyrinth disk 12 to its downstream surface 22.

It can be seen that the internal stiffener 9 is of reduced shape. On the other hand, a main stiffener 23 is provided in the middle of the labyrinth disc 12, that is to say on the rim 13. Its shape is such that it forms a toric bead which protrudes over the downstream surface 22 of the labyrinth disc 12 , just below the labyrinth lips 10, below the passages 11. Its downstream end is at the same longitudinal level as the downstream end of the downstream surface 22 of the arch 14. Lower orifices 15 are also provided so that 'a relatively small part of the cold air flow passing from upstream to downstream with respect to the labyrinth disc can pass below and around this main stiffener 23, between the latter and the upstream surface 19 of the disc 8 of the rotor. Such a cold air flow allows to cool this main stiffener 23 and the downstream surface 22 of the labyrinth disc 12. The two fresh air flows passing through the passages 11 and the lower orifices 15 meet behind the labyrinth disc 10 on the downstream surface 22 of the arch 14 to go back up between the fixing teeth 24. They thus cool the entire rear of this assembly which constitutes the labyrinth disc. They reach the rim of the turbine disk 8 and join the cooling circuits of the blades 21 and the fixing cells of these blades.

This main stiffener 23 constitutes the main mechanical holding element of the labyrinth disc 10. It contributes to reducing the internal stiffener 9 and reducing the general dimension of the labyrinth disc 10 and, in particular, of the arch 14. It is noted that the latter may have a slightly less rounded shape but slightly offset towards the downstream side of the labyrinth disc 12 to come almost to tangent with the upstream surface 19 of the disc 8 of the rotor.

The general flexibility of the rim 13 of the labyrinth disc 12 is retained because this main stiffener 23 is located a little offset downstream. This main stiffener 23 being closer to the operational elements of the labyrinth disk 12, that is to say the labyrinths themselves 10, it makes it possible to ensure better mechanical strength of these. In addition, this main stiffener 23 increases the thermal response time of the labyrinth disk 12, since it is placed in the central part of the latter. It improves the compatibility of the radial displacements of the labyrinth disc 12 with respect to the disc 8 of the turbine and thus reduces the forces on the upper support means of the labyrinth disc 12. The latter also constitute part of the means for fixing the disc. labyrinth 12 on the rotor.

Indeed, in the outer part, these can be constituted by fixing teeth 24 placed on the downstream surface 22 of the labyrinth disk 12 and, in particular, on the outer part of the arch 14. Opposite these , on the upstream surface 19 of the disc 8 of the rotor, there are fixing teeth 25 of a bayonet locking system in number corresponding to the number of fixing teeth 24 of the labyrinth disc 12. Thus, once in its radial position and axial, the labyrinth disk 12 can be rotated by half a step of the fixing teeth 24 and 25 to be fixed behind the fixing teeth 25 of the bayonet locking system.

The axial positioning of the labyrinth disk 12 is ensured with respect to the disk 8 of the rotor, by means of the downstream surface 22 of the rim 13 and of the arch 14. In the solution, shown in FIG. 1, ribs 26 are placed on the downstream surface 22 of the arch 14 to stiffen the latter. They bear on the downstream surface 22 of the disc 8 of the rotor and thus constitute axial stops. Recall that the labyrinth disk 12 can be fixed by a bolt system 6 in its interior.

Radial stops 27 can be provided on the upstream surface 19 of the disc 8 of the rotor, just below the bayonet fixing teeth 25, so as to bear on the external surface of the fixing teeth 24 of the labyrinth disc 12. The stops radials 27 face the fixing teeth 24 only when the part is in the locking position in the bayonet system.

In this embodiment, no other fixing system is useful. This avoids a possible fixing hook at the level of the downstream surface 22 of the rim 13, or of the arch 14.

In this embodiment, part of the radial loads is absorbed by the radial stops 27, a part being absorbed by the main stiffener 23 and a small part being passed on to the bolts 6.

FIG. 3 represents a first variant of the labyrinth disk according to the invention. It shows the use of holes 30 placed on the base 31 of the main stiffener 33 which is unique and which, therefore, is a little more elongated, but still placed just below the labyrinth 10. In addition, the system of bayonet fixing comes down to a single series of teeth 34 on the labyrinth disc 32, since these act both as fixing teeth by being housed behind the fixing teeth 35 for fixing the bayonet locking system of the disc 38 rotor and also act as radial stops, thanks to their inclined surfaces combined with the corresponding inclined surfaces of the fixing teeth 35 of the disc 38 of the rotor. These fixing teeth 34 of the labyrinth disc 32 are preferably housed in the upper part of ribs 36.

The second variant, represented by FIG. 4, takes up the same holes 30 in the main stiffener 33. On the other hand, the fixing system described in FIG. 2 is the same. In other words, the same set of fixing teeth 24 is used there on the labyrinth disc 42, placed in correspondence with fixing teeth 25 on the disc 8 of the rotor to constitute the bayonet system. Radial stops 28 are provided in the outer part of the ribs 26 and placed in correspondence with stops 27 of the disc 8 of the rotor.

FIG. 5 shows a third variant, still using the single main stiffener 33, extended to provide for the use of holes 32 on either side of the stiffening disc 52. In this version, the radial stops 58 are placed further outside. with respect to the fixing system. They are placed opposite abutment surfaces 59 of the disc 8 of the rotor. The axial fixing is effected by means of a bayonet fixing system at the level of the ribs 56. They use teeth 54 engaging in teeth of the bayonet locking system 55 corresponding to the discs 8 of the rotor.

The fourth variant of FIG. 6 shows a different shape from the vault 64 of the labyrinth disk 62. Indeed, from its external end 61, this is almost straight, that is to say that its downstream surface 63 is more spaced from the disc 68 of the rotor than in the other embodiments. As a result, the ribs 66 are wider.

The number of variants can also be increased by changing the means of fixing the labyrinth disk to the rotor disk. In fact, with reference to FIG. 7, the bolting attachment can be omitted to be replaced by a bayonet style attachment. In this case, inside and upstream of the main stiffener 33, there is an axial ring 71, the sectional view of which gives it the shape of a lug, as shown in this FIG. 7. Similarly, the disc 78 of the rotor also has an axial ring 77 extending substantially parallel to the axis A of the turbojet engine in order to come into contact with the end of the axial ring 71 of the labyrinth disc 72.

The fixing means consist, on the labyrinth disk 72, of a series of pins 74 each penetrating into a groove 76 formed on the outer surface 79 of the axial ring 77 of the disk 78 of the rotor. The insertion of these pins 74 can be done by means of longitudinal notches 75 machined on this external surface 79 of the axial ring 77 of the disc 78 of the rotor. Centering is obtained by direct contact of these two parts at the level of the external surface 79 of the axial ring 77 of the disc 78 of the rotor.

In all these embodiments, the dimensioning of this assembly, which constitutes the labyrinth disk, is less difficult in its design and makes it possible to obtain longer service lives.

The operating capacities of such a part allow a much more severe thermomechanical environment, thanks to the distribution of the masses accumulating heat and the ventilation system of this assembly which constitutes the labyrinth disc.

Claims (9)

Labyrinth disk (12, 32; 42, 52, 62) for a turbomachine rotor comprising: - a main rim (13, 63); - a labyrinth (10) incorporated into the rim (13); - a roof (14, 64) placed in the external extension of the rim (13, 63) to bear on the upstream surface (19) of the disc (8, 38, 58, 68) of the rotor, and - means for fixing the labyrinth disc (12, 32, 42, 52, 62) to the disc (8) of the rotor, characterized in that it comprises a main radial stiffener (23, 33), incorporated in the rim ( 13, 63), just inside the labyrinth (10). Labyrinth disc (12, 32, 42, 52, 62) according to claim 1, characterized in that the vault (14, 64) is an upper part of the rim (13, 63) fairly elongated radially, slightly curved, its surface downstream (22) being placed at the axial level of the downstream end of the main stiffener (23, 33). Labyrinth disc (12, 32, 42, 52, 62) according to claim 1, characterized in that the fixing means consist, in the lower part of the rim (13) and upstream of the main stiffener (23), of fixing holes intended to receive fixing bolts (6). Labyrinth disc (12, 32, 42, 52, 62) according to claim 1, characterized in that the fixing means consist of fixing teeth (24, 34, 54) intended to be placed behind fixing teeth of a bayonet locking system (25, 35, 55) fixed to the disc (8, 38, 58, 68) of the rotor. Labyrinth disc (12, 32, 42, 52, 62) according to claim 3, characterized in that radial stops (28, 58) are provided to come into contact with rotor stops (27, 59) on the upstream surface (19) thereof. Labyrinth disc (12, 32, 42, 52, 62) according to claim 1, characterized in that the vault (14, 64) comprises ribs (26, 56, 66) of the vault (14, 64). Labyrinth disc (12, 32, 42, 52, 62) according to claim 4, characterized in that the arch (14) comprises ribs (26) in the lower extension of the fixing teeth (24). Labyrinth disc (12, 32, 42, 52, 62) according to claim 4, characterized in that the axial stops consist of the interior of the fixing teeth (34). Labyrinth disc (12, 32, 42, 52, 62) according to claim 1, characterized in that the vault (14) acts as an axial stop by means of ribs (26).

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