FR3058495B1 - 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

Dual-stage sealing device, labyrinth seal and mobile 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 especially in turbomachines, typically aircraft turbojets. A turbomachine usually comprises a fixed part, called a stator, which comprises stationary blades, and a movable part, called a rotor, which comprises moving blades. A flow of gas, called vein, flows between the blades. It is important that this stream is properly channeled. For this purpose, it is sought to minimize 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 may be solid or honeycombed (typically with a honeycomb structure). The wipers are designed to rub against the track and thus provide a dynamic seal to the gas flow. These wipers may be in the form of continuous or segmented blades on the periphery of the rotor. They generally extend radially outwardly thereof.

An architecture of this type is illustrated in the 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 cause deviations in the expansions of the various parts, and in particular between the track and the wipers. Depending on the operating cycle of the turbomachine, interstices may appear between the wipers and the track, which results in a leakage.

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

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

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

An object of the present invention is therefore to provide a solution for improving the sealing of the rotor-stator connection of a rotating 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 resumes its shape after being contracted. For this purpose, it is proposed, in the first place, 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 mounted wiper hinged by at the base between an upright position and a retracted position, inclined with respect to the upright position, a return means mounted between the base and the wiper, exerting a return force on said wiper and urging the wiper towards its upright position .

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

According to various features, taken alone or in combination: the biasing means is a leaf spring, which comprises a core applied against the base, and a wing applied against the wiper; the base comprises a projecting holding wedge, against which the core is applied by an edge opposite the wing; the wing of the return means is fixed on the wiper. ; the wing is attached to the wiper by means of a weld (eg solder); the base comprises an abutment against which comes the wiper in the erect position.

According to a particular embodiment, the device comprises at least three wipers, namely a pair of small wipers, and a large articulated wiper disposed 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 adjacent angular elements or sectors, a rotating part, mounted in rotation with respect 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 in contact each with with a lateral portion of the runway, and a large articulated wiper arranged between the small wipers and in contact with the intermediate portion of the runway when in the erect 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 constitutive of the stator and the rotating part integral or constitutive of 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 non-limiting 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;

3 is a view of a detail of FIG.2, according to the box III, showing the sealing device in erected 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 engine) intended to equip an aircraft such as an airplane. This is a dual flow reactor, which comprises a blower 2 ensuring an initial compression of the incoming air. The air leaving the fan 2 is separated into two streams, namely a primary flow that passes through the entire turbine engine 1, and a secondary flow that bypasses it.

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

The compressors 3, 4 and the turbine 6 have a similar overall architecture. FIG. 2 is a sectional view of a detail of the turbine 6. As illustrated in FIG. 2, each assembly 3, 4, 6 comprises: a rotor 7 including at least one series of disks 8 and a plurality of movable vanes 9 extending radially from the disk 8 around which the vanes 9 form a corolla; a stator 10 which comprises an outer casing 11 and a plurality of fixed blades 12 interposed between the blades 9 movable rotor 7. As shown in FIG.2, the discs 8 are fixed to each other to be secured in rotation.

It can be seen that the wingspan 9 extends from left (upstream side) to right (downstream side), to accompany the increase in volume of the air as it spreads.

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

Each stator vane 12 has an integral outer portion of the housing 11 and a foot 15 connected to a ring 16 symmetrical with respect to the axis X. The ring 16 comprises an axial portion, cylindrical of revolution, bearing 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 may have a track formed of several elements (or angular sectors) contiguous.

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

The present invention proposes 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, of which the part stationary is integral or constituent of the stator 10 and the rotating part integral or constituent of 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 application example 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 moving wheel of turbine engine.

An embodiment of the device 18 to ensure a seal at this interface is presented in FIG.3. FIG. 3 is a detail view of FIG. 2, according to box III. The device 18 is intended to be interposed between the ring 16 (fixed part) and the labyrinth shell 14 (rotating part). It comprises: a base 20 secured to the labyrinth shell 14, at least one wiper 19 articulated relative to the base 20 between an erect position P1 and a retracted position P2, inclined relative to the upright position P1, a means of return 21 mounted between the base 20 and the wiper 19 and urging it to its upright position P1.

FIG. 3 illustrates the raised 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 a position inclined relative to the upright position P1.

The presence of the return means 21 ensures a permanent contact between the wiper 19 and the fixed part 16, to the benefit of the sealing of the interface. The stiffness of the return means 21 is determined numerically according to the maximum inclination angle 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 facilitates the mounting of the device between the rotating part 14 and the fixed part 16. This joint can be achieved through a pivot connection.

The return means 21 used may 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 comprise a holding wedge 24 projecting against which the core 22 is applied by an edge opposite the wing 23.

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

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

As shown in the embodiment of FIG.3 and FIG.4, the base 20 comprises a stop 20a against which comes to apply the wiper 19 in upright position P1.

According to the particular embodiment shown in FIGS. 3 and 4, the device comprises at least three wipers, namely a pair of small wipers 25, and a large articulated wiper 19 disposed between the small wipers 25. The use different sizes of wipers makes it possible to complicate the path of passage of the gas at the interface between the fixed part 16 and the base 20. A large wiper 19 has been deliberately positioned between two small wipers 25, since this produces a configuration in double staggering. that the gas should rise and fall alternately to cross the interface, making it more difficult to pass through the interface. Depending on the types of devices used, the interstices between the wipers have a length generally between 5 and 15 millimeters.

According to an embodiment presented in FIGS. 3 and 4 FIG.4: the track 17 defines at least three cylindrical portions anotées 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. Indeed the track 17 may have portions as shown in FIG.3 of different diameters.

A step of mounting the device 18 is to translate 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 may end up in abutment against the portion D1 of the track 17. The retracted position P2 of the articulated wiper 19 thus facilitates its passage so that it does not abut against the portion D1. Once its passage completed, the return means 21 urges it to its upright position P1, so that at the end of the assembly, the wiper 19 is in contact with the portion D2 of the track 17.

Thus, this invention makes it possible to guarantee the assembly of any type of labyrinth-type sealing devices, whatever their complexities. It also creates more complex labyrinth devices that increase the imperviousness of the interfaces between the rotors and the stators in the 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) integral with the rotating part (14), at least one wiper (19) mounted articulated with respect to the base (20) between an upright position (P1) and a retracted position (P2), i nclined with respect to the upright position (P1), characterized in that it comprises means for return (21) mounted between the base (20) and the wiper (19), exerting a return force on said wiper and urging it to 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 le (24) of projecting support, 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 flange (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 on 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 is applied the wiper (19) upright (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 wiper (19) articulated disposed between the small wipers (25). 8. An assembly comprising: a fixed piece (16) of abradable material forming a track (17) having a symmetry of revolution or formed of an assembly of several adjacent angular elements or sectors, a rotating part (14), rotatably mounted by relative to the fixed part (16), a sealing device (18) according to any one of the preceding claims. 9. The assembly of claim 8, characterized in that: the track defines at least three cylindrical portions, namely two side 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 in the upright position (P1). 10. A turbomachine (1) comprising a stator (10) and a rotor (7), and an assembly according to claim 8 or claim 9, the fixed piece (16) is integral with or constituent of the stator (10) and the piece rotating (14) integral or constituent of the rotor (7).