FR3058495A1 - DOUBLE SHAPE SEALING DEVICE, LABYRINTH SEAL AND MOBILE LATCH - Google Patents

Abstract

There is provided a device (18) for sealing an interface between a fixed part (16) and a rotating part, this device comprising: a base (20) integral with the rotating part; at least one wiper (19) mounted articulated with respect to the base between an upright position (P1) and a retracted position, inclined with respect to the upright position; characterized in that it comprises a return means (21) mounted between the base (20) and the wiper (19) and biasing it to its upright position (P1).

Description

Holder (s): SAFRAN AIRCRAFT ENGINES Simplified joint-stock company.

Extension request (s)

Agent (s): ERNEST GUTMANN - YVES PLASSERAUD SAS.

TWO-STAGE SEALING DEVICE, LABYRINTH SEAL AND MOBILE WASHER.

FR 3 058 495 - A1 (3 /) || is proposed a device (18) for sealing an interface between a fixed part (16) and a rotating part, this device comprising: a base (20) integral with the rotating part; at least one wiper (19) mounted articulated relative to the base between an upright position (P1) and a retracted position, inclined relative to the upright position; characterized in that it comprises a return means (21) mounted between the base (20) and the wiper (19) and urging the latter towards its upright position (P1).

Double-stage sealing device, labyrinth seal and movable wiper

The present invention relates to the field of sealing devices, and more particularly to labyrinth sealing devices.

This type of sealing device is found in particular in turbomachinery, typically aircraft jet engines. A turbomachine ordinarily comprises a fixed part, called a stator, which comprises fixed blades, and a mobile part, called a rotor, which comprises mobile blades. A flow of gas, called a vein, flows between the vanes. It is important that this flow is properly channeled. To this end, we seek to minimize the air currents bypassing the blades, at the interface between the rotor and the stator. This function is provided by sealing devices, which each comprise, on the one hand, a track integral with the stator, and, on the other hand, radially projecting seal elements, called "wipers" integral with the rotor.

The track is generally made of an abradable material, which can be solid or honeycombed (typically with a honeycomb structure). The wipers are designed to rub against the track and thus ensure a dynamic seal against gas flows. These wipers can be in the form of continuous or segmented blades around the periphery of the rotor. They generally extend radially outward from it.

An architecture of this type is illustrated in French patent application FR 3 027 341.

In operation, the wipers slide on the track, which thus undergoes wear by mechanical friction. The thermal cycles undergone by the turbomachine can generate deviations in the expansions of the different parts, and in particular between the track and the wipers. Depending on the operating cycle of the turbomachine, gaps may appear between the wipers and the track, which results in a leak.

To improve sealing, it has been proposed, cf. French patent application FR 3 027 622, to articulate the wipers relative to the rotor, so that from a certain speed of rotation these wipers come into contact with the track of abradable material.

However, tightness is not guaranteed until the speed has reached a threshold value. In addition, the risk exists of seizure of the wipers, due to the presence, in their articulation, of particles resulting from the wear of the abradable material.

So the architecture of French patent application FR 3 027 622, despite the progress it provides compared to that of application FR 3 027 341, cannot guarantee perfect sealing of the rotor-stator connection.

An objective of the present invention is therefore to propose a solution for improving the sealing of the rotorstator connection of a rotary machine, such as a turbomachine.

In this document, the expression "return means" is used to designate an elastic member (typically a spring) capable of deforming and which returns to its shape after being contracted.

To this end, it is proposed, firstly, a device for sealing an interface between a fixed part and a rotating part, this device comprising:

a base secured to the rotating part, at least one wiper mounted articulated relative to the base between an upright position and a retracted position, inclined relative to the upright position, a return means mounted between the base and the wiper, exerting a return force on said wiper and urging it towards its upright position.

In this way, the wiper is permanently in contact with the fixed part, to the benefit of the sealing of the interface. Furthermore, this architecture makes it easier to mount the device between the rotating part and the fixed part.

According to various characteristics, taken alone or in combination: the return means is a leaf spring, which comprises a core applied against the base, and a wing applied against the wiper; the base includes a protruding holding wedge, against which the core is applied by an edge opposite the wing;

the wing of the return means is fixed to the wiper. ;

the wing is fixed to the wiper by means of a weld (eg a solder);

the base includes a stop against which the wiper is applied in the upright position.

According to a particular embodiment, the device comprises at least three wipers, namely a pair of small wipers, and a large articulated wiper arranged between the small wipers.

It is proposed, secondly, an assembly comprising: a fixed piece of abradable material forming a track having a symmetry of revolution or formed of an assembly of several elements or angular sectors joined together, a rotating part, mounted in rotation relative to the fixed part, a sealing device as described above.

According to one embodiment:

the track defines at least three cylindrical portions, namely two lateral portions separated by an intermediate portion of larger internal diameter, and the device comprises at least three wipers, namely a pair of small wipers each in contact with a lateral portion of the track, and a large articulated wiper, placed between the small wipers and in contact with the intermediate portion of the track when it is in the upright position.

It is proposed, thirdly, a turbomachine comprising a stator and a rotor, and an assembly as presented above, the fixed part of which is integral with or constituting the stator and the rotating part integral with or constituting the rotor.

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of nonlimiting example with reference to the drawings, in which:

FIG.1 is a perspective sectional view of an aircraft turbojet engine;

FIG.2 is a sectional view of a detail of the turbomachine of FIG.1;

FIG.3 is a detail view of FIG.2, according to insert III, showing the sealing device in the upright position of the large wiper;

FIG.4 is a view similar to FIG.3, illustrating the retracted position of the large wiper.

FIG. 1 shows a turbomachine 1 (in this case a turbojet) intended to equip an aircraft such as an airplane. This is a double flow reactor, which includes a blower 2 ensuring initial compression of the incoming air. The air leaving the blower 2 is separated into two flows, namely a primary flow which crosses the entire turbomachine 1, and a secondary flow which bypasses it.

To compress and guide the gases of the primary flow, the turbomachine 1 comprises several successive sets 3, 4, 5, 6 or stages, namely: a low pressure compressor 3 downstream of the fan 2, a high pressure compressor 4 downstream of the low pressure compressor 3, a combustion chamber 5 downstream of the high pressure compressor 4, and a turbine 6 downstream of the combustion chamber 5.

The hot gases exiting through the downstream of the combustion chamber 5 cause the turbine 6 to rotate, which in turn drives the compressors 3, 4 of which it is integral.

The compressors 3, 4 and the turbine 6 have an overall similar architecture. FIG.2 is a sectional view of a detail of the turbine 6. As illustrated in FIG.2, each set 3, 4, 6 comprises:

a rotor 7 including at least one series of discs 8 and a plurality of movable vanes 9 which extend radially from the disc 8 around which the vanes 9 form a corolla;

a stator 10 which comprises an outer casing 11 and a plurality of stationary vanes 12 interposed between the movable vanes of the rotor 7. As illustrated in FIG.2, the discs 8 are fixed to each other so as to be made to rotate.

We see that the wingspan of the blades 9 increases from left (upstream side) to right (downstream side), to accompany the increase in air volume as it spreads.

Each disc 8 is rotated about a common X axis. The discs 8 are interconnected by ferrules inter3058495 discs 13. Each pair of blades 9 of rotor 7 separated by a stator blade 12, is connected by a ferrule 14 called labyrinth ferrule.

Each stator vane 12 has an external part integral with the casing 11 and a foot 15 connected to a ring 16 symmetrical in revolution with respect to the X axis. The ring 16 comprises an axial part, cylindrical in revolution, carrying a track 17 made of abradable material. In the example presented, the ring 16 has a symmetry of revolution but this case is not limiting. The ring 16 can have a track formed of several elements (or angular sectors) joined.

The labyrinth shell 14 carries metallic wipers whose tips are in contact with the abradable track 17 in order to impede the passage of air at the foot of the stator vanes 12.

The present invention provides a turbomachine comprising a stator 10, a rotor 7, and a device 18 making it possible to guarantee, for each assembly 3, 4, 6, a seal at the interface between a fixed part and a rotating part, the part of which fixed is integral with or constituting the stator 10 and the rotating part integral with or constituting the rotor 7. In the embodiment shown, the fixed part refers to the ring 16 and the rotating part to the labyrinth shell 14.

The example of application presented (interface between a rotor and a stator) not being limiting, the present invention can also be applied at any interface between two parts of a turbomachine, for example at the top of a wheel mobile turbomachine.

An exemplary embodiment of the device 18 making it possible to guarantee sealing at this interface is presented in FIG. 3. FIG.3 is a detail view of FIG.2, according to inset III. The device 18 is intended to be interposed between the ring 16 (fixed part) and the labyrinth shell 14 (rotating part). He understands :

a base 20 secured to the labyrinth shell 14, at least one wiper 19 mounted articulated relative to the base 20 between an upright position P1 and a retracted position P2, inclined relative to the upright position P1, a return means 21 mounted between the base 20 and the wiper 19 and urging the latter towards its upright position P1.

FIG.3 illustrates the upright position P1 of the articulated wiper 19 while FIG.4 illustrates the retracted position P2 of this same wiper. The retracted position P2 corresponds to an inclined position relative to the upright position P1.

The presence of the return means 21 ensures permanent contact between the wiper 19 and the fixed part 16, for the benefit of the sealing of the interface. The stiffness of the return means 21 is determined numerically as a function of the maximum angle of inclination of the articulated wiper 19. For example, the order of magnitude of the stiffness of the return means 21 is around 10 N.mm / rad in the case of a maximum inclination of 45 °.

Furthermore, the articulation of the large wiper 19 makes it possible to facilitate the mounting of the device between the rotating part 14 and the fixed part 16. This articulation can be achieved by means of a pivot connection.

The return means 21 used can be a leaf spring, which comprises a core 22 applied against the base 20, and a wing 23 applied against the wiper 19.

The base 20 may include a projecting support wedge 24, against which the core 22 is applied by an edge opposite the wing 23.

According to a preferred embodiment, the wing 23 of the return means 21 is fixed to the wiper, for example by means of a weld (eg a solder).

According to another possible embodiment (not shown), a retaining wedge can be formed projecting from the wiper and the wing 23 is then applied against this wedge by an edge opposite the core 22. In this case, the the core 22 is fixed to the base 20, for example by means of a weld (eg a solder).

As presented in the embodiment of FIG.3 and FIG.4, the base 20 includes a stop 20a against which the wiper 19 is applied in the upright position P1.

According to the particular embodiment presented in FIG.3 and FIG.4, the device comprises at least three wipers, namely a pair of small wipers 25, and a large hinged wiper 19 disposed between the small wipers 25. Use wipers of different sizes makes it possible to make the path of gas passage at the interface between the fixed part 16 and the base more complex. A large wiper 19 has been positioned voluntarily between two small wipers 25, since this produces a double-layered configuration according to which the gas should rise and fall alternately to cross the interface, which makes it more difficult to pass through the interface. Depending on the types of device used, the gaps between the wipers have a length generally between 5 and 15 millimeters.

According to an embodiment presented in FIG. 3 and FIG. 4: the track 17 defines at least three annotated cylindrical portions D1, D2, namely two lateral portions D1 separated by an intermediate portion D2 of larger internal diameter, and the device comprises at least three wipers, namely a pair of small wipers 25 each in contact with a lateral portion D1 of the track, and a large articulated wiper 19, disposed between the small wipers 25 and in contact with the intermediate portion D2 of the track 17 when in the upright position P1.

The arrow M indicates the direction of assembly of the device 18. In fact the track 17 may have portions as shown in FIG.3 of different diameters.

A step in mounting the device 18 consists in translating the base 20 relative to the fixed part 16 in the direction of the arrow M. During this translation, the end 19a of the large wiper 19 risks finding itself in abutment against the portion D1 of the track 17. The retracted position P2 of the articulated wiper 19 thus makes it easier to pass so that it does not come into abutment against the portion D1. Once its passage is completed, the return means 21 urges it towards its upright position P1, so that at the end of the assembly, the wiper 19 is in contact with the portion D2 of track 17.

Thus, this invention makes it possible to guarantee the mounting of all types of sealing devices of the labyrinth type, whatever their complexities. It also creates more complex labyrinth devices that increase the tightness of interfaces between rotors and stators in motors. This invention thus offers the advantage of improving engine performance.

Claims (10)

1. Device (18) for sealing at the interface between a fixed part (16) and a rotating part (14), this device comprising a base (20) secured to the rotating part (14), at least one wiper (19) hinged rise relative to the base (20) between an upright position (P1) and a retracted position (P2), inclined relative to the upright position (P1), characterized in that it comprises a means of return (21) mounted between the base (20) and the wiper (19), exerting a return force on said wiper and urging it towards its upright position (P1). 2. Device (18) according to claim 1, characterized in that the return means (21) is a leaf spring, which comprises a core (22) applied against the base, and a wing (23) applied against the wiper (19). 3. Device (18) according to claim 2, characterized in that the base (20) comprises a ca the (24) projecting holding, against which the core is applied by an edge opposite the wing (23) . 4. Device (18) according to claim 2 or claim 3, characterized in that the wing (23) of the return means (21) is fixed on the wiper (19). 5. Device (18) according to claim 4, characterized in that the wing (23) is fixed to the wiper (19) by means of a weld or a solder. 6. Device (18) according to any one of the preceding claims, characterized in that the base (20) comprises a stop (20a) against which the wiper (19) is applied in the upright position (P1). 7. Device (18) according to any one of the preceding claims, characterized in that it comprises at least three wipers, namely a pair of small wipers (25), and a large articulated wiper (19) disposed between the small wipers (25). 8. Set including: a fixed part (16) of abradable material forming a track (17) having a symmetry of revolution or formed by an assembly of several joined angular elements or sectors, a rotating part (14), mounted in rotation relative to the fixed part (16), a sealing device (18) according to any one of the preceding claims. 9. An assembly according to claim 8, characterized in that: the track defines at least three cylindrical portions, namely two lateral portions (D1) separated by an intermediate portion (D2) of larger internal diameter, and the device (18) comprises at least three wipers, namely a pair of small wipers (25) each in contact with a lateral portion (D1) of the track, and a large articulated wiper (19), disposed between the small wipers (25) and in contact with the intermediate portion (D2) of the track when it is in the upright position (P1). 10. Turbomachine (1) comprising a stator (10) and a rotor (7), and an assembly according to claim 8 or claim 9, the fixed part (16) of which is integral or constitutive of the stator (10) and the part rotating (14) integral with or constituting the rotor (7). 1/3 2/3