FR3079590A1 - CONNECTING DEVICE FOR AIR CIRCUIT OF AN AIRCRAFT ENGINE - Google Patents

Abstract

The invention relates to a connection device (7) for an air circuit of an aircraft engine, comprising two end pieces, respectively male (14) and female (13), configured to be engaged by axial translation one. in the other, the end pieces being able to move axially or radially relative to each other in operation, characterized in that it further comprises an annular bellows (19) extending around said end pieces (13). , 14) and having a first axial end sealingly attached to the spigot (14) and a second opposite axial end sealingly attached to the spigot (13), said annular bellows (19) being adapted to elastically deform to allow relative movements of said tips.

Description

CONNECTION DEVICE FOR AN AIR CIRCUIT OF AN AIRCRAFT ENGINE

Technical area :

The present invention relates to the field of aircraft engines and more particularly to the auxiliary air circuits necessary for its operation.

State of the art :

In particular, an aircraft engine of the turbomachine type generally comprises an auxiliary air circuit bringing air taken from a compressor stage to activate or heat certain organs. This type of circuit has a complex shape to reach different parts of the engine. It is made up of several branches which must be connected together. Furthermore, these circuit branches are subjected to different stresses according to the engine operating regimes, which places great stress on the junction elements between them.

For example, the auxiliary air circuit may include a branch supplying air at the level of the hood separation spout surrounding the low pressure compressor for use in the anti-icing system. The smallness of the space at the level of the separation nozzle strongly constrains the design of the connection between this branch of the air circuit and the duct which supplies it. On the one hand, there are few margins for taking up any faults during the manufacturing of the parts, on the other hand, the thermal expansions during the operation of the engine imply relative displacements between the branch inserted near the separation nozzle and the duct bringing the air from the compressor. It is therefore necessary, in this case, to leave a certain degree of freedom to the relative displacement of these two elements at their junction.

It can also be seen that slippery connections between these two elements, with a contact ensuring sealing, exhibit significant wear of the parts rubbing one on the other after a certain period of operation of the engine. This phenomenon can cause leaks and be a cause of failure.

The object of the invention is therefore to be able to make a sealed connection between two elements of an air circuit in an aircraft engine by allowing play between these two elements, whether to compensate for differences in mounting or displacement relative during engine operation.

A second objective of the invention is to achieve this by disturbing the flow at the connection as little as possible.

Presentation of the invention:

The invention relates to a connection device for an air circuit of an aircraft engine, comprising two end pieces, male and female respectively, configured to be engaged by axial translation one inside the other, the end pieces being suitable to move axially or even radially with respect to each other in operation, characterized in that it further comprises an annular bellows extending around said end pieces and comprising a first axial end fixed in leaktight manner on the end piece male and a second opposite axial end fixed in leaktight manner on the female end piece, said annular bellows being able to deform elastically to allow relative movements of said end pieces.

Here, the axial and radial directions are understood in relation to the direction of engagement of the tips one in the other, which also corresponds to the main direction of the air flow passing through them.

The tips, which can move relative to each other, at least in the axial direction, they give a degree of freedom to the connection device. On the other hand, the bellows seals the space around the end pieces, between its two ends. So it allows to leave games between the tips to allow relative movement by limiting wear by friction.

Advantageously, each of said first and second ends of said annular bellows is tightly fixed to a radially external annular rib of the corresponding end piece.

The ribs form a geometric pattern facilitating the attachment of the bellows. In addition, each rib forms a stop for the axial displacement of the corresponding end of the bellows.

Advantageously, said first end of the annular bellows is mounted tight against the annular rib of said male end piece by an annular clamping collar which is mounted at least partly around this rib.

Advantageously, said second end of the annular bellows is mounted shrunk or in force on the annular rib of the female end piece.

Preferably, said second end of the annular bellows is mounted tight on a frustoconical surface of said rib.

Advantageously, the annular bellows has an internal diameter less than or equal to the external diameter of said ribs and an external diameter greater than the external diameter of the ribs.

The fact that the internal diameter of the bellows is less than the external diameter of the ribs makes it possible to reduce the stresses of fixing its ends to the rib, which by being axial stops are not likely to pass under the ends when the bellows is compressed. Furthermore, the larger the external diameter of the bellows, in particular at the level of its longitudinal oscillations, the more this makes it possible to give it flexibility.

Advantageously, the first and / or the second end of the annular bellows are configured so as to resiliently tighten an outer wall of the corresponding end piece.

Preferably, the annular bellows is metallic, so as to resist the constraints of its environment.

The invention also relates to an aircraft engine, comprising a low pressure compressor and a high pressure compressor, comprising such a connection device which is located in an annular space extending around the low pressure compressor or between the low pressure compressors and high pressure.

In this case, one of the nozzles can be connected to a pipe fixed to an upstream compressor casing, and the other of the nozzles can be connected to a pipe connected to a downstream compressor casing.

Brief description of the figures:

The present invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description which follows, with reference to the appended drawings in which:

FIG. 1 represents an axial section of a turbomachine element at the level of the separation nozzle between the primary circuit and the secondary circuit, integrating a device according to the invention.

FIG. 2 represents a detailed view of the installation of the device according to the invention present in FIG. 1, with a section along an axial plane.

FIG. 3 represents an enlargement of FIG. 2 at the level of the device according to the invention.

FIG. 4 represents a perspective view from above of the device of FIGS. 2 and 3.

Description of an embodiment of the invention:

With reference to FIG. 1, an exemplary implementation of the invention is described on a connection device in a deicing air circuit for a separation spout between the primary flow and the secondary flow of a turbine engine. FIG. 1 represents the portion of the turbomachine comprising the stator 1a and rotor 1b elements of the low pressure compressor installed at the inlet of the primary circuit, with the external casing 2 of the compressor forming a wall of the stream of the primary flow and the outer cover 3 forming the inner wall of the secondary flow stream.

The defrost air circuit includes a ramp 4a-4b supplying hot air to an annular cavity 5 in contact with the walls of the separation nozzle, in order to prevent icing of the latter. To control the distribution of hot air in the annular cavity 5, the ramp here comprises an annular tube 4a, surrounding the casing 2 of the low pressure compressor, connected to the cavity 5 by at least one axial bypass 6. The supply of hot air from the anti-icing ramp is made, here on the high point, by an axial tubular inlet 4b of the latter. The two ends of the annular tube 4a meet at the level of the axial inlet 4b and are connected to the latter by a Y-shaped separation. This shape is more visible in FIG. 4.

The axial inlet 4b of the anti-icing ramp is connected by the connection device 7 to a supply tube 8, bringing hot air taken from the engine by means not shown since they are not affected by the 'invention.

The ramp 4a-4b is held in position by fixing means 9 on the casing 2 of the low pressure compressor. These fixing means 9 are more explicitly shown in Figure 4, in the form of a retaining ring.

It will be noted here that the annular space close to the separation spout, where the anti-icing ramp 4a-4b and the connection device 7 are located, is very limited. The connection device 7 is located upstream in the annular space delimited by the casing 2 of the low pressure compressor and the cover 3. The supply tube 8 is held on a casing 10 located downstream of the low pressure compressor, by means which are not represented. The connection device 7 is positioned so that the end of the supply tube 8 which is fixed to it crosses without contact a control ring 11 (better visible in FIG. 2) of discharge doors 12 installed at the outlet of the low pressure compressor or at the inlet of the high pressure compressor (not shown). As indicated in the introduction, this configuration induces for the two connected elements, 4b and 8, constraints of deformation, during assembly, and of differential displacements, during operation, that the connection device 7 must absorb.

With reference to FIGS. 2, 3 and 4, the connection device 7 according to the invention comprises a first end piece 13, secured to the axial inlet 4b of the anti-icing ramp, and a second end piece 14, secured to the end of the tube supply 8. The two end pieces 13, 14 are engaged one in the other in a main direction X which here is substantially the axial direction of the turbomachine. In the example, the end piece 14 secured to the supply tube 8 is the male end piece and the end piece 13 secured to the inlet 4b of the anti-icing ramp is the female end piece, but the reverse is possible. in an alternative embodiment.

In the example, the walls of the two end pieces 13, 14 are substantially circular and have a minimum clearance over their entire circumference, thus ensuring minimum leakage between the two walls while allowing axial sliding between the end pieces. However, this configuration constrains relative displacements in the radial direction.

In a variant not shown, the section of the end pieces is not circular but, for example rectangular. It is then possible to leave a greater clearance between the faces perpendicular to the same transverse direction, thus allowing relative displacements of the end pieces in this transverse direction. In such a variant, may thus allow small relative displacements of the tips in the radial direction relative to the turbomachine, for example to take account of thermal expansions in operation.

Here, the external wall of the male end piece 14 comprises a cylindrical part in order to be able to slide inside the female end piece 13. In the example considered, the male end piece 14 comprises an annular rib 15 radially external, located axially at the end of said cylindrical part on the side of the supply tube 8. Here the maximum diameter of the rib 15 is greater than the inside diameter of the female end piece

13, thus forming an axial stop. A portion of the cylindrical part of the male end

14, located against the rib 15, protrudes from the female end piece 13 to allow axial movements.

The annular rib 15 is inserted into an annular clamping collar 16, the internal shape of which fits around that of said rib.

The external wall of the female end piece 13 comprises a cylindrical part between its free end and the inlet 4b of the anti-icing ramp. A radially outer annular rib 17 is placed at the axial end of this cylindrical part on the side of the ramp, also forming an axial stop. The rib 17 here has a frustoconical surface 18 on its side oriented towards the cylindrical part, more particularly visible in FIG. 3.

Here, the connection device is provided for the passage of an air flow supplying the anti-icing ramp 4a-4b, therefore going from the male end piece 14 to the female end piece 13, as indicated by the arrow on the Figure 3. The inner wall of the female end piece 13 forms a housing for the movement of the male end piece 14, which opens onto a transition section with the inlet 4b of the anti-icing ramp. The assembly is configured so as to guide the air flow by disturbing it as much as possible and to avoid pressure drops, in particular by ensuring that the internal wall of said transition section on the female end piece 13 is in continuity with the internal wall of the male end 14.

According to the manufacturing methods, the male end piece 14 and the female end piece 13 can be mechanically mounted, respectively, on the feed tube 8 and on the inlet 4b of the ramp, or else come in one piece with them.

The connection device 7 is completed by an annular bellows 19, mounted around the end pieces 13, 14 between the ribs 15, 17 previously described, in order to ensure sealing. The longitudinal profile of the annular bellows 19 has an appropriate number of corrugations to give it great flexibility in axial but also lateral deformation. The material of the bellows 19 is preferably metallic to resist the constraints of its environment.

The internal diameter of the bellows 19 is less than the external diameter of the ribs 15, 17, present at the ends of the end pieces 13, 14, so that it can be trapped axially between the two ribs. The outside diameter of the bellows 19, at the end of the corrugations, is here significantly greater than that of the ribs 15, 17, to give it great flexibility. This outer diameter is however constrained by the space available between the casing 2 of the low pressure compressor and the outer cover.

3.

Advantageously, the unconstrained length of the bellows 19 is greater than the distance separating the ribs 15, 17, present on the end pieces 13, 14, for the maximum axial displacements provided between the latter, so that the ends of the bellows 19 support naturally against these ribs. Advantageously, the internal diameter of the bellows is slightly less than the diameter of the external wall of the cylindrical portion of the female end piece 13, so that the bellows 19 is pressed, by elasticity, against the external wall of the cylindrical portion of the 'female end piece 13. Advantageously also, the bellows 19 comprises, at the end situated on the side of the rib 15, a part having a diameter slightly less than the diameter of the cylindrical part of the male end piece 14, so as to be pressed by elasticity against the cylindrical part of said tip. The bellows 19 then forms a tight sleeve which presses, between the two ribs 15, 17, on the cylindrical portion of the female end piece 13 and on the exposed portion of the cylindrical part of the male end piece 14.

However, the seal is reinforced here by means illustrated more precisely in FIG. 3, to avoid leaks during the relative movements of the end pieces 13, 14.

On the side of the rib 15 of the male end piece 14, the end of the bellows 19 comprises a cylindrical part which is inserted between the annular clamping collar 16 and the external wall of the end piece 14, while axially abutting against the rib 15. During assembly, this cylindrical part is pinched against the rib 15 of the end piece 14 by the clamp 16, thus closing the space between the bellows 19 and the male end piece 14, whatever the displacements of this last.

On the side of the rib 17 of the female end piece 13, the axial end of the bellows 19 is mounted hooped on the frustoconical surface 18 of the rib 17, which also makes it possible to join them whatever the movements of the female end piece 13. In a variant, the end of the bellows 19 can be force-fitted on the rib 17.

The collaboration of the bellows 19 and the two end pieces 13, 14 thus allows the device 7 to ensure the airtightness of the air circuit at its level while allowing relative movements of the two elements, 4b and 8, which it connects.

Claims (10)

claims 1. Connection device (7) for an air circuit of an aircraft engine, comprising two nozzles, male (14) and female (13) respectively, configured to be engaged by axial translation, one in the other, the end pieces being able to move axially or even radially with respect to each other in operation, characterized in that it further comprises an annular bellows (19) extending around said end pieces (13, 14) and comprising a first axial end fixed in a sealed manner on the male end piece (14) and a second opposite axial end fixed in a sealed manner on the female end piece (13), said annular bellows (19) being able to deform elastically for authorize the relative movements of said tips. 2. Connection device (7) according to the preceding claim, characterized in that each of said first and second ends of said annular bellows (19) is tightly fixed to an annular rib (15, 17) radially external to the end piece ( 13, 14) corresponding. 3. Connection device (7) according to claim 2, characterized in that said first end of the annular bellows (19) is mounted tight against the annular rib 17 of said male end piece (14) by an annular clamping collar (16) which is mounted at least in part around this rib. 4. Connection device (7) according to claim 2 or 3, characterized in that said second end of the annular bellows (19) is mounted hooped or forced on the annular rib (17) of the female end piece (13). 5. Connection device (7) according to claim 4, characterized in that said second end of the annular bellows (19) is mounted clamped on a frustoconical surface (18) of said rib (17). 6. Connection device (7) according to one of claims 2 to 5, characterized in that the annular bellows (19) has an internal diameter less than or equal to the external diameter of said ribs (15, 17) and a greater external diameter the outer diameter of the ribs. 7. Connection device (7) according to one of the preceding claims, characterized in that the first and / or the second end of the bellows are configured so as to resiliently clamp an outer wall of the corresponding end piece. 8. Connection device (7) according to one of the preceding claims, characterized in that the annular bellows (19) is metallic. 9. aircraft engine, comprising a low pressure compressor (1a-1b) and a high pressure compressor, characterized in that it comprises a device (7) according to one of the preceding claims which is located in an annular space s 'extending around the low pressure compressor or between low pressure and high pressure compressors. 10. aircraft engine according to the preceding claim, characterized in that one of the end pieces (13) is connected to a pipe (4b) fixed to an upstream casing (2) of the compressor, and the other (14) of the end pieces is connected to a pipe (8) connected to a downstream compressor casing (10).