FR2960519A1 - Aerodynamic fairing i.e. rear lower aerodynamic fairing, for hooking device i.e. hooking strut, of turbo-jet engine in aircraft, has stiffener including pressed flange extending along stiffener direction - Google Patents

Abstract

The fairing (30) has a thermal protection floor (32) provided with an outer surface intended to be adopted by primary flow of an engine, where the fairing forms a box comprising lateral panels (44) assembled with each other by transversal rigidification inner ribs (46). Each panel is equipped with a stiffener (50) fixed to the panel for extending along a stiffener direction (52) parallel to the ribs. The stiffener has a pressed flange (56) extending along the stiffener direction. The stiffener is made of TAV6 titanium alloy.

Description

FIELD OF THE INVENTION The present invention relates to an aerodynamic fairing for an attachment device for an engine intended to be interposed between an aircraft wing and the engine. concerned, this fairing being also called "shield" or "APF" (of the English "Aft Pylon Fairing").

Such an attachment device, also known as an engine mounting structure ("EMS"), makes it possible to suspend an engine below the wing of the aircraft, to mount this engine at above this same wing, or to mount it laterally in the rear part of the fuselage. An example of an attachment device is known from WO 2009/037267.

In the case where the engine is suspended under the wing, then the fairing concerned is said "lower rear aerodynamic fairing".

More specifically, the invention relates to the stiffeners that equip the side panels of this aerodynamic fairing.

The invention can be used on any type of aircraft equipped with turbojet engines or turboprop engines. STATE OF THE PRIOR ART An attachment device is in fact provided to constitute the connection interface between an engine and a wing of the engine. aircraft. It transmits to the structure of this aircraft the forces generated by its associated engine, and also allows the flow of fuel, electrical, hydraulic, and air between the engine and the aircraft.

In order to ensure the transmission of forces, the attachment device comprises a rigid structure also called primary structure, often

of the "caisson" type, that is to say formed by the assembly of upper and lower spars and

side panels connected together through transverse stiffening ribs.

On the other hand, the device is provided with hooking means interposed between the engine and the rigid structure, these means generally comprising two engine attachments, and a device for taking up the thrust forces generated by the engine. In the prior art, this recovery device usually comprises two lateral rods connected on the one hand to a rear part of the fan housing of the engine, and on the other hand to a rear attachment fixed to the central casing of the latter.

In the same way, the attachment device also comprises another series of fasteners constituting a mounting system interposed between the rigid structure and the wing of the aircraft, this system usually consisting of two or three fasteners.

Furthermore, the mast is provided with a plurality of secondary structures segregating and maintaining the systems while supporting aerodynamic fairing elements, the latter generally taking the form of panel assemblies reported on the structures. In a manner known to those skilled in the art, the secondary structures are different from the rigid structure in that they are not intended to ensure the transfer of forces from the engine and to be transmitted to the wing of the aircraft.

Among the secondary structures, there is the lower rear aerodynamic fairing, also called APF, which has a plurality of functions among which is noted the formation of a thermal or fire barrier, and the formation of aerodynamic continuity between the engine output and the engine mount.

The lower rear aerodynamic fairing generally takes the form of a box comprising two side panels assembled together by transverse stiffening internal ribs spaced from each other in a longitudinal direction of the fairing, and a thermal protection floor. It is specified that this box may not be completely closed opposite the thermal protection floor, namely in the upper part when the engine is intended to be suspended under the wing of the aircraft, since it is at this place that it comes to connect on the other structures of the mast.

The thermal protection floor is provided with an outer surface adapted to be wedged by a primary flow of the engine that it delimits, while the side panels are provided for being wedged externally by a secondary flow of the engine, because their implantation in the annular channel of secondary flow of the engine, and / or output thereof.

To improve the mechanical strength of the side panels of the lower rear aerodynamic fairing, they are generally equipped with stiffeners fixedly fixed against these panels, extending in a direction of stiffening

substantially parallel to the planes of transverse stiffening ribs. Usually, this direction of stiffener is the vertical direction of the pylon.

The stiffeners thus positioned are

stressed in compression and / or traction. They make it possible to reinforce the overall mechanical strength of the aerodynamic fairing. However, the need to resume significant efforts can lead to a high sizing stiffeners, which penalizes the overall weight of the fairing.

DISCLOSURE OF THE INVENTION The object of the invention is therefore to remedy at least partially the disadvantages mentioned above, relating to the embodiments of the prior art.

To do this, the subject of the invention is an aerodynamic fairing for a coupling device for an engine intended to be interposed between an aircraft wing and said engine, said casing fairing comprising two lateral panels assembled together by ribs. internal transverse stiffening spaced apart from each other in a longitudinal direction of said fairing, and further comprising a thermal protection floor provided with an outer surface intended to be married by a primary flow of said engine, each side panel being further equipped with at least one stiffener attached to said panel and extending in a direction of stiffener substantially parallel to said transverse internal stiffening ribs.

According to the invention, said stiffener comprises a pressed flange extending in said direction of stiffener.

The presence of such a stamped bead on the stiffener considerably improves the ratio between its mechanical strength and its mass. For example, a stiffener stamped such a stiffening rod has a buckling resistance which can be nearly four times greater than that of the same non-stamped stiffener.

The aerodynamic fairing can then have a high overall mechanical strength, while maintaining a reasonable mass.

Preferably, said pressed flange extends for a length of between 70 and 95% of the total length of the stiffener, in said stiffener direction.

Preferably, said pressed flange has a thickness of between 5 and 15% of the total length of the stiffener, in said direction of stiffener.

Preferably, said stiffener is also fixed on said thermal protection floor and on a closing beam of the fairing, opposite said floor and assembled to said transverse internal stiffening ribs. In the case where the engine is suspended under the wing, it is then the upper spar of the box-shaped fairing, this spar can be full or partially open.

Preferably, said stiffener comprises a main core extending in said stiffener direction, as well as a first and a second connecting tab respectively protruding from the two opposite ends of the main core, and a third connecting tongue. protruding laterally from said main core and in said stiffener direction.

Finally, said stiffener is made of a titanium alloy TAV6, which is entirely suitable for producing the bead by stamping.

The invention also relates to a device for attaching an engine intended to be interposed between an aircraft wing and the engine,

Device comprising an aerodynamic fairing as described above. In the case where the engine is suspended under the wing, it is then the fairing

aerodynamic lower back of the shackle. In the other case where the engine is mounted above the wing, it is then the upper rear aerodynamic fairing.

In addition, the invention also relates to an engine assembly comprising a motor such as a turbojet engine and a coupling device of this engine, this device being in accordance with the one just mentioned.

Finally, another object of the present invention is an aircraft comprising at least one such engine assembly.

Other advantages and features of the invention will become apparent in the detailed non-limiting description below. BRIEF DESCRIPTION OF THE DRAWINGS This description will be made with reference to the appended drawings among which; FIG. 1 represents a schematic side view of an aircraft engine assembly, comprising an attachment device according to a preferred embodiment of the present invention;

- Figure 2 shows a schematic side view of the lower rear aerodynamic fairing equipping the hooking device shown in Figure 1, the fairing being also an object of the present invention;

Figure 3 is a perspective view of a portion of the lower rear aerodynamic fairing shown in Figure 2; and - Figures 4 and 5 show enlarged perspective views of a stiffener belonging to the lower rear aerodynamic fairing shown in Figure 3; and FIG. 6 shows a sectional view taken along the line VI-VI of FIG. 5. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, an engine assembly 1 for an aircraft intended to be fixed under FIG. a wing 2 of this aircraft, this assembly 1 comprising an attachment device 4 according to a preferred embodiment of the present invention, as well as a motor 6 such as a turbojet engine hung under this device 4.

Overall, the attachment device 4 comprises a rigid structure 8, also called a primary structure, carrying means for attaching the motor 6, these attachment means having a plurality of engine attachments 10, 12, and a device for taking up the thrust forces 14 generated by the engine 6.

As an indication, it is noted that the assembly 1 is intended to be surrounded by a nacelle (not shown), and that the attachment device 4 comprises another series of fasteners (not shown) reported on the rigid structure 8 and to ensure the suspension of this assembly 1 under the wing 2 of the aircraft.

Throughout the following description, by convention, X is the longitudinal direction of the device 4 which is also comparable to the longitudinal direction of the turbojet engine 6 and that of the lower rear aerodynamic fairing which will be presented hereinafter, this direction X being parallel to a longitudinal axis 5 of the turbojet engine 6. On the other hand, the direction transversely oriented with respect to the device 4 and also comparable to the transverse direction of the turbojet engine 6 and that of the lower rear aerodynamic fairing, and Z la vertical direction or height, these three directions X, Y and Z being orthogonal to each other.

On the other hand, the terms "front" and "rear" are to be considered in relation to a direction of advancement of the aircraft encountered following the thrust exerted by the turbojet engine 6, this direction being represented schematically by the arrow 7.

In FIG. 1, it is therefore possible to see the two engine attachments 10, 12, the thrust force take-up device 14, the rigid structure 8 of the attachment device 4, as well as a plurality of secondary structures attached to the structure. rigid 8. These secondary structures ensuring the segregation and maintenance of the systems while supporting aerodynamic fairing elements will be described below.

It is stated that the turbojet engine 6 has at the front of a large fan casing 18 delimiting an annular fan duct 20, and comprises a rearward central casing 22 of smaller size, enclosing the core of this fan. turbojet. Housings 18 and 22 are of course integral with each other.

As can be seen in Figure 1, the engine fasteners 10, 12 of the device 4 are provided in the number of two, respectively called front engine attachment and rear engine attachment.

In this preferred embodiment of the present invention, the rigid structure 8 takes the form of a box extending from the rear to the front, substantially in the X direction.

The casing 8 then takes the form of a mast of similar design to that usually observed for the turbojet latches, in particular in that it is provided with transverse ribs (not shown) each taking the form of a rectangle oriented in a YZ plane.

The attachment means of this preferred embodiment firstly comprise the engine attachment before 10 interposed between a front end of the rigid structure 8 also called pyramid, and an upper portion of the fan casing 18. The engine attachment before 10 is designed in a conventional manner and known to those skilled in the art.

On the other hand, the rear engine attachment 12, also made in a conventional manner and known to those skilled in the art, is interposed between the rigid structure 8 and the central casing 22.

Still with reference to FIG. 1, the secondary structures of the mast 4 include a front aerodynamic structure 24, a rear aerodynamic structure 26, a connecting fairing 28 of the front and rear aerodynamic structures, and a lower rear aerodynamic fairing 30.

Overall, these secondary structures are conventional elements identical or similar to those encountered in the prior art, and known from

the person skilled in the art, with the exception of the lower rear aerodynamic fairing 30 which will be detailed below.

More specifically, the front aerodynamic structure 24 is placed in the lower front extension of the wing 2 and above the primary structure 8. It is fixedly mounted on the rigid structure 8, and has an aerodynamic profile function between an upper part fan cowls hinged thereto, and the leading edge of the wing. This aerodynamic structure before 24 then not only has an aerodynamic fairing function, but also allows the introduction, segregation and routing of different systems (air, electrical, hydraulic, fuel). In addition, the front part of this structure 24 is not in contact with the rigid structure 8, it is usually interposed a heat exchanger in the space defined between these two elements.

Directly in the rear extension of this structure 24, still under the wing and mounted above the rigid structure 8, is the

connection fairing 28, also called

"Karman". Then, still towards the rear, the connecting fairing 28 is extended by the rear aerodynamic structure 26, which contains most of the hydraulic equipment. This structure 26 is preferably located entirely rearward with respect to the rigid structure 8, and is therefore attached under the wing of the aircraft.

Finally, under the rigid structure 8 and the rear aerodynamic structure 26, is the lower rear aerodynamic fairing 30, also called "shield" or "Aft Pylon Fairing". Its essential functions are the formation of a thermal barrier also called fireproof used to protect the mast and the wing from the heat released by the flow

primary, and the formation of aerodynamic continuity between the engine output and the engine mount.

The shroud 30 mentioned above has a thermal protection floor 32, or lower spar, provided with an outer surface intended to be wedged by a primary flow of the motor which it delimits partially radially outwards, this primary flow escaping from the nozzle 33 of the engine being shown schematically by the arrow 36. Furthermore, the shroud 30 also comprises two side panels 44 which are in turn provided to be matched externally by a secondary flow of the motor shown schematically by the arrow 38, due their implantation in the annular channel 40 of secondary flow of the engine, and / or output thereof.

It is noted that in the preferred embodiment described where the engine 6 is intended to be suspended under the wing of the aircraft, the floor 32 for thermal protection of the mast and the wing vis-à-vis the primary flow 36, is a lower portion of the shroud 30. Naturally, this floor would be an upper portion of the fairing in the alternative case where the engine would be intended to be implanted above the wing.

Finally, as can be seen in FIG. 1, it is envisaged that the front end of the floor 32 will marry the upper rear end of the nozzle 33, or that it will be very close to the same rear end of the nozzle 33 .

Referring now to FIGS. 2 and 3, the lower rear aerodynamic fairing 30 can be seen in more detail, which takes the general form of a box closed upwards by an upper spar 35, that is to say towards the other structures of the mast 4 on which it is

intended to be mounted, namely the rear aerodynamic structure 26 and the rigid structure 8. The upper spar 35 can be full or open, the openings made can then be used as access hatches inside the box.

The shroud 30 preferably has a plane of symmetry P corresponding to a plane XZ, this plane P also constituting a vertical plane of symmetry for the whole of the attachment device 4, and for the engine 6.

The box-shaped lower rear aerodynamic fairing 30 further comprises the two side panels 44 (only one visible in each of Figures 2 and 3 for the sake of clarity), each of the panels 44 being roughly oriented in an XZ plane, from and others of the plane P. They are assembled together by transverse transverse stiffening ribs 46 spaced apart from each other in the direction X, each of these ribs 46 being oriented along a plane YZ. These transversely oriented ribs 46 are also assembled on the upper and lower spars 32, thus making it possible to hold together all the outer members 32, 35, 44 forming the box.

To increase the mechanical strength of

panels 44, these are each equipped with a plurality of stiffeners fixedly fixed against these panels. As an indicative example, each panel 44 may carry a stiffener 50 between each pair of directly consecutive ribs 46.

Figures 4 to 6 show the design of one of the stiffeners 50, which is one of the features of the present invention. In this regard, it is stated that the stiffeners 50 may all be made in the manner now to be described, or some of them may retain a more conventional design, as known from the prior art.

The stiffener 50 shown in Figures 4 to 6 extends generally in a direction of stiffener referenced 52, parallel to the planes of the ribs 46, and which here corresponds substantially to the direction Z.

The stiffener 50 essentially comprises a substantially planar main core 54, extending in the direction 52. Within this core 54, which is preferably arranged in a YZ plane, a deep-drawn bead 56 is produced which considerably strengthens the resistance. mechanical conferred by the stiffener, both in traction and compression.

The flange 56, which has a generally semicircular overall shape in section as best seen in FIG. 6, extends over a length of between 70 and 95% of the total length of the stiffener in the direction 52. Its thickness , corresponding generally to a half-diameter, is in turn between 5 and 15% of the total length of the flange.

In the figures, the flange 56 is open towards the front, but could alternatively be open towards the rear, without departing from the scope of the invention. The realization of this coil is made by stamping the core 54 in the form of a metal plate, for example with a thickness of the order of 2 mm, by stamping means known to those skilled in the art. Here, it is preferentially used a titanium alloy TAV6 for the realization of the stiffener.

At the opposite ends of the core 54, the stiffener 50 has a first 58a and a second connecting tab 58b respectively projecting from said two ends. These tabs 58a, 58b corresponding to curved upper and lower edges, preferably at about 90 °. The upper tongue 58a then allows the connection of the stiffener to the upper spar 35, while the lower tongue 58b allows the connection of this stiffener to the shield 32. The two tabs 58a,

58b, forming part of XY planes, are preferably rigidly assembled by bolts or rivets to their associated element 35, 32. They are preferably curved in the same direction as that of the embodiment of the coil 56.

Similarly, a third connecting tongue 60 is provided laterally projecting from the core 54. Here again, the tongue 60 corresponding to a curved lateral edge of the core, preferably at about 90 °. This lateral tab 60, which extends substantially all along the soul in the

direction 52, then allows the connection of the stiffener to the panel 44 against which the tongue 60 is in plane support, and fixed rigidly by bolts or rivets. The lateral tongue 60 thus inscribes a plane XZ, and is preferably curved in the same direction as that of the embodiment of the coil 56.

Finally, it is indicated that the three tabs described above can be obtained from the same plate incorporating the core 54, which is stamped to obtain the coil 56, and then folded at its ends and at one end. from its lateral edges to obtain the three tabs 58a, 58b, 60.

Of course, various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples. In this respect, it is possible in particular to indicate which if the engine assembly 1 has been presented in a configuration adapted to be suspended under the wing of the aircraft, this assembly 1 could also be in a different configuration allowing it to 'to be mounted above this same wing, or even in the rear part of the fuselage.5

Claims (10)

REVENDICATIONS1. Aerodynamic fairing (30) for a coupling device (4) for a motor (6) intended to be interposed between an aircraft wing (2) and said engine (6), said caisson fairing comprising two lateral panels (44). ) joined together by transverse stiffening ribs (46) spaced apart from one another in a longitudinal direction (X) of said fairing, and further comprising a thermal protection floor (32) provided with an outer surface to be espoused by a primary flux (36) of said motor, each side panel (44) being further provided with at least one stiffener (50) fixed to said panel and extending in a stiffener direction (52) substantially parallel to said inner ribs transverse stiffening device (46), characterized in that said stiffener (50) comprises a pressed flange (56) extending in said stiffener direction (52). 2. Fairing according to claim 1, characterized in that said pressed flange (56) extends over a length of between 70 and 95% of the total length of the stiffener, in said direction of stiffener. 3. Fairing according to claim 1 or claim 2, characterized in that said pressed flange (56) has a thickness of between 5 and 15% of the total length of the stiffener, in said direction of stiffener. 4. Fairing according to any one of the preceding claims, characterized in that said stiffener (50) is also fixed on said thermal protection floor (32) and on a closing beam (35) of the fairing (30) opposite said floor (32) is connected to said transverse reinforcing ribs (46). The fairing according to any one of the preceding claims, characterized in that said stiffener (50) comprises a main web (54) extending in said stiffener direction (52), as well as first and second webs connection (58a, 58b) respectively protruding from the two opposite ends of the main core (54), and a third connecting tongue (60) laterally projecting from said main core (54) and in said stiffening direction ( 52). 6. Fairing according to any one of the preceding claims, characterized in that said stiffener (50) is made of a titanium alloy TAV6. 7. An attachment device (4) for a motor (6) intended to be interposed between an aircraft wing (2) and said engine (6), characterized in that it comprises an aerodynamic fairing (30) according to the invention. any preceding claim. 8. Device according to claim 7, characterized in that said aerodynamic fairing (30) is a lower rear aerodynamic fairing of the attachment device. Motor assembly (1) comprising a motor (6) and an attachment device (4) for the motor (6) according to claim 8. An aircraft comprising at least one engine unit (1) according to claim 9.