Thrust-reversal system for an aircraft turbojet engine, nacelle and propulsion unit comprising such a system

Abstract

The invention relates to a thrust-reversal system comprising: at least one movable cowl (20), movable between a retracted position and a deployed position; a set of air deflection devices (22); at least one shut-off device (24) for shutting off the secondary duct (16a) and movable between a retracted position corresponding to the retracted position of the movable cowl (20), in which position the shut-off device is at least partially housed in a space (200) provided in the movable cowl (20), and a deployed position corresponding to the deployed position of the movable cowl (20), in which position the shut-off device (24) is at least partially deployed into the secondary duct (16a), so as to deflect a majority portion of the secondary airflow towards the air deflection devices (22); the thrust-reversal system comprising at least one deployable membrane (22, 24), the deployable membrane (22, 24) comprising at least one reinforcement.

Description

Thrust reversal system for aircraft turbojet, nacelle and propulsion unit comprising such a system Technical Field

[0001] The invention relates to the field of nacelles and thrust reversers for aircraft propulsion systems, and, more particularly, to thrust reversers equipped with deployable membranes. State of the art

[0002] Thrust reversers are systems that deflect the airflow passing through the propulsion system forward, in order to shorten landing distances and limit the load on the brakes on the landing gear.

[0003] The grid reversers currently used in the aeronautical sector generally comprise deflection grids integrated into a fixed structure of the reverser, intended to be connected to a turbomachine casing. A movable structure of the reverser comprises one or more movable reverser cowls, and it is mounted so as to be movable in translation relative to the fixed structure between a forward direct thrust position, and a rearward thrust reverser position. In the forward direct thrust position, the deflection grids are arranged in a cavity of the movable reverser cowls, and they are isolated from the secondary flow stream of the propulsion unit by a radially internal wall of the reverser cowls. On the other hand, in the rearward thrust reverser position, the rearward radially internal wall of the reverser cowls defines an opening for the passage of the secondary flow stream towards the deflection grids.

[0004] To divert at least part of the secondary flow towards this passage opening in the direction of the grilles, the inverter is generally equipped with shutters, which, when deployed, at least partially close the secondary vein. In a known manner, this forces the air of the secondary flow to pass through the passage opening and reach the grilles, which then generate the counter-thrust air flow towards the front.

[0005] The shutter solution is also known for being relatively heavy and bulky. However, climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various carbon emission restrictions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new aircraft types and also to those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0006] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0007] With this in mind, solutions have been developed for closing the secondary vein using one or more deployable membranes. Such a membrane design is known, for example, from document FR 3 076 864 Al.

[0008] The deployment of a sealing membrane can be carried out using one or more deployment rods, one radially external end of which is connected to one end of the membrane, and one radially internal end of which is articulated on a radially internal delimiting wall of the secondary vein, this wall belonging to the fixed structure of the inverter.

[0009] As the moving structure moves towards its rearward thrust reversal position, the membrane gradually deploys into the vein, plunging radially inwards, driven by the connecting rod(s) which tilt downstream and also radially inwards.

[0010] In the direct jet position, the end of the membrane connected to the connecting rods is generally sandwiched between a deflection edge of the fixed structure, and an upstream end of the radially internal wall of the movable hood.

[0011] It has also been proposed to replace all or part of the deflection grilles with deployable deflection membranes, or deflector membranes. The deflector membranes are, when the mobile structure is in the rearward thrust reversal position, in a deployed position, in which they are at least partially deployed outside the structure formed by the nacelle, so as to deflect towards the outside of the nacelle and towards the front the part of the secondary flow deflected by the shutter flaps or by the shutter membranes. When the mobile structure is in the forward direct jet position, the deflection membranes are folded into an internal space provided in the movable hood.

[0012] It appears that both the shutter membranes and the deflection membranes are subjected to very significant forces during thrust reversal phases, and must, however, be able to be easily folded into a limited space when the nacelle is in direct jet configuration. The membranes are also subjected to significant turbulence during thrust reversal phases, which is likely to degrade them. These constraints are likely to limit the service life of these elements.

[0013] The objective of the present invention is to improve the robustness and durability of deployable membranes equipping a thrust reverser, while limiting their mass. Statement of the invention

[0014] For this purpose, the invention relates to a thrust reversal system for an aircraft turbojet nacelle, the thrust reversal system delimiting a secondary vein for the passage of the secondary flow of the turbojet, the thrust reversal system comprising: at least one movable cowl, movable between a retracted position, in which the thrust reversal system is in a direct jet configuration, and a deployed position, in which the thrust reversal system is in a reverse jet configuration; a set of air deflection devices;at least one device for closing the secondary flow, movable between a retracted position corresponding to the retracted position of the movable cover, in which the closing device is at least partially housed in a space provided in the movable cover, and a deployed position corresponding to the deployed position of the movable cover, in which the closing device is at least partially deployed in the secondary flow, so as to divert a majority portion of the secondary flow towards the air diversion devices; the thrust reversal system comprising at least one deployable membrane, the deployable membrane comprising at least one reinforcement.

[0015] Thus, by providing at least one reinforcement on each deployable membrane, whether it is a sealing membrane or a deflection membrane, the robustness of the deployable membranes is improved, as well as their durability. In the context of the invention, the deployable membrane can form at least one of the air deflection devices and / or at least one of the secondary vein sealing devices.

[0016] The thrust reverser system according to the invention may comprise one or more of the following optional features, considered alone or in all possible combinations.

[0017] According to one feature, the deployable membrane forms at least one of the deflection devices, the deployable membrane comprising an air outlet and an air outlet reinforcement, the air outlet reinforcement extending along a front end of the deployable membrane forming the air outlet.

[0018] According to one feature, the deployable membrane forms at least one of the deflection devices, the deployable membrane comprising a dorsal portion and a dorsal reinforcement extending in an axial direction along the dorsal portion.

[0019] According to one feature, the deployable membrane forms at least one of the deflection devices, the deployable membrane comprising a base and a base reinforcement, extending along a lower end of the base.

[0020] According to one feature, the deployable membrane forms at least one of the deflection devices, the deployable membrane comprising a central strip extending in a longitudinal direction in front of the air outlet, and comprising two longitudinal reinforcements extending along the lateral ends of the central strip.

[0021] According to one feature, the deployable membrane forms at least one of the sealing devices, the deployable membrane comprising at least one internal circumferential reinforcement and / or at least one external circumferential reinforcement.

[0022] According to one feature, the deployable membrane forms at least one of the sealing devices, the deployable membrane comprising one or more reinforcements axial, circumferentially spaced from each other, and extending from a radially inner edge to a radially outer edge of the deployable membrane.

[0023] According to one characteristic, the or at least one of the reinforcements has a different number of strand(s) from one end to an opposite end.

[0024] According to one feature, the reinforcements are attached to the corresponding deployable membrane, for example by gluing and / or sewing, or are inserted into pockets provided in the corresponding deployable membrane.

[0025] The invention also relates to a nacelle comprising a thrust reversal system in accordance with that defined above.

[0026] The invention also relates to a propulsion unit comprising a dual-flow turbojet and a nacelle comprising a thrust reversal system in accordance with that defined above.

[0027] The invention also relates to an aircraft comprising at least one propulsion unit as defined above. Brief description of the drawings

[0028] Figure 1 is a perspective view of an aircraft propulsion assembly, comprising a bypass turbojet engine and a nacelle carrying a grid thrust reverser system, the thrust reverser system being shown in a retracted configuration.

[0029] Figure 2 shows the propulsion assembly of Figure 1, with the thrust reverser system shown in a deployed configuration.

[0030] Figure 3 is a partial view of a propulsion assembly conforming to that of Figure 1, the nacelle carrying a reversing system with deflector membranes, the thrust reversing system being in a deployed configuration.

[0031] Figure 4 is a partial view of the rear section of the nacelle of Figure 1, when the reversal system comprises at least one shutter membrane, the thrust reversal system being in a deployed configuration.

[0032] Figure 5 is a schematic sectional view of the rear section of the nacelle of Figure 1, when the thrust reverser system comprises at least one shutter membrane and at least one deflection membrane, the thrust reverser system being in the retracted configuration.

[0033] Figure 6 is a view similar to Figure 5, showing the thrust reverser system in the deployed configuration.

[0034] Figure 7 is a schematic perspective view of a first example of a deflection membrane, showing more particularly a front portion of the deflection membrane.

[0035] Figure 8 is a schematic perspective view of the deflection membrane of Figure 7, showing more particularly a rear portion of the deflection membrane.

[0036] Figure 9 is a schematic perspective view of a second example of a deflection membrane, showing more particularly a front portion of the deflection membrane.

[0037] Figure 10 is a schematic perspective view of the deflection membrane of Figure 9, showing more particularly a rear portion of the deflection membrane.

[0038] Figure 11 is a schematic perspective view of a third example of a deflection membrane.

[0039] Figure 12 is a schematic view of a first example of the production of a reinforcement.

[0040] Figure 13 is a schematic view of a second example of the embodiment of a reinforcement.

[0041] Figure 14 is a schematic view of a third example of the embodiment of a reinforcement.

[0042] Figure 15 is a schematic view of a fourth example of the embodiment of a reinforcement.

[0043] Figure 16 is a schematic view of the sealing membrane of Figure 4, seen from the front.

[0044] Figure 17 is a rear view of the sealing membrane of Figure 16.

[0045] Figure 18 is a schematic view of an example of the embodiment of a reinforcement, in the example a reinforcement for a sealing membrane.

[0046] Figure 19 is a detailed perspective view of the thrust reverser system of Figure 4. Detailed description

[0047] Figures 1 and 2 show an aircraft propulsion unit 1, having a longitudinal central axis A.

[0048] Subsequently, the terms "upstream" and "downstream" are defined relative to a general direction of flow of gases through the propulsion unit, along the axis A when it generates thrust. These terms "upstream" and "downstream" could respectively be substituted by the terms "front" and "rear", with the same meaning.

[0049] The propulsion unit 1 comprises a turbomachine 2 and a nacelle 3. The propulsion unit 1 is intended to be connected via a mast 4 to a wing (not shown) of an aircraft.

[0050] The turbomachine 2 is in this example a dual-flow turbojet engine, comprising in particular a gas generator and a fan. The nacelle 3 comprises a front section 10 forming an air inlet 10a, a middle section 12 which comprises two fan cowls 12a surrounding a fan casing of the turbojet engine, and a rear section 16.

[0051] In operation, an air flow enters the propulsion unit 1 through the air inlet 10a, passes through the fan of the turbojet engine and then divides into a primary flow and a secondary flow. The primary flow flows in a primary gas circulation vein passing through the gas generator of the turbojet engine 2. The secondary flow flows in a secondary vein surrounding the gas generator. The secondary vein is delimited radially inwards by an internal structure of the nacelle which envelops the gas generator.

[0052] The rear section 16 of the nacelle carries a thrust reverser system 18. Figure 1 shows nacelle 3 in direct jet configuration, i.e. with the system thrust reverser in the retracted position, while Figure 2 shows the nacelle 3 in reverse jet configuration, that is to say with the thrust reverser system in the deployed position. Thus, it can be seen in Figure 3 that a movable cowl 20 of the rear section 16 is in the retracted position, revealing a set of air deflection devices 22, which are in the example of Figures 1 and 2 air deflection grilles.

[0053] Figure 3 is a partial view of the rear section 16 of the nacelle 3 of the propulsion unit 1, in a variant in which the air deflection devices 22 are deflection membranes 22, or deflector membranes. As visible in Figure 3, which shows the thrust reversal system 18 in the deployed position, all of the deflection membranes 22 are deployed, so as to redirect the secondary air flow outside the nacelle 3, towards the front. In the example, the deflection membranes 22 are configured to be deployed, in a radial direction (relative to the longitudinal axis A), outside the envelope formed by an external surface of the movable cowl 20 when the latter is in the retracted position. In other words, as seen in Figure 3, the deflection membranes protrude radially, when deployed, relative to the aerodynamic line formed by the movable hood 20.

[0054] Figure 4 represents a half-part of the rear section 16 of the nacelle 3, which shows the thrust reverser system 18 in the deployed configuration, in a variant in which it comprises at least one sealing membrane 24.

[0055] As seen in Figure 4, each half-part of the rear section 16 of the nacelle comprises an internal fixed structure 160 (also called IFS according to the English term "Inner Fixed Structure") and an external fixed structure 162 (also called OFS according to the English term "Outer Fixed Structure"). In the example, the rear section 16 of the nacelle has a so-called "D-shaped" structure (commonly referred to by the English term "D-duct"). In such a configuration, the internal fixed structure 160 and the external fixed structure 162 are connected to each other at the level by means of two connecting islands 164, 166, arranged in the secondary vein 16a, respectively forming a first bifurcation 164 and a second bifurcation 166.For a propulsion unit attached to an aircraft wing, the bifurcations are arranged respectively in the positions known as "at twelve o'clock" (for the first bifurcation, or upper bifurcation 164) and "at six o'clock" (for the second bifurcation, or lower bifurcation. 166). It is recalled that the “twelve o’clock” and “six o’clock” positions are conventionally defined by analogy with a watch dial, the nacelle being in the operating position, i.e. under the wing. The “twelve o’clock” position is thus located at the nacelle attachment mast, while the “six o’clock” position corresponds to the diametrically opposite position. For a propulsion unit fixed to the fuselage of an aircraft, the bifurcations will be arranged according to the so-called “three o’clock” and “nine o’clock” positions. Furthermore, although the nacelle described in the present application has a D-shaped structure, the present invention applies to any type of nacelles, and in particular to nacelles having an “O” or “C” structure, structures in which only a single bifurcation is provided.

[0056] Figures 5 and 6 are schematic sectional views of the rear section 16 of the nacelle 3, in a variant in which the thrust reversal system 18 comprises at least one closure membrane 24 and at least one deflection membrane 22.

[0057] In the configuration of figures 1 and 5, the secondary vein 16a is, at the level of the rear section 16, delimited by the internal fixed structure 160, and the movable cowls 20, which form a part of the rear section 16 of the nacelle 3. The secondary vein 16a is in direct jet configuration and is optimized to allow the secondary flow to pass towards the rear of the propulsion unit, opposing it with the lowest possible resistance.

[0058] In the configuration of figures 2, 3, 4 and 6, the movable cowls 20 are in the retracted position and the secondary vein 16a is at least partially obstructed by a device for closing the secondary vein, in the example a closing membrane 24. In its deployed position, the closing membrane 24 makes it possible to block part of the secondary flow to redirect it towards the air deflection devices 22 and therefore towards the outside of the nacelle, thus generating the desired counter-thrust.

[0059] As can be seen more particularly in Figures 5 and 6, the thrust reversal system 18 comprises at least one movable cowl 20, in the example two movable cowls 20, which form the outer surface of the rear section 16 of the nacelle. The thrust reversal system 18 further comprises the air deflection devices 22 and the devices 24 for closing the secondary vein 16a. The thrust reversal system 18 comprises actuators (not shown), in particular electromechanical actuators, making it possible to slide the movable cowl between a position retracted (figure 5) and a deployed position (figure 6), and vice versa. This transition is carried out by a translational movement along the longitudinal axis of the nacelle, corresponding to the longitudinal axis A of the propulsion unit 1.

[0060] When the thrust reverser system 18 is in the retracted position (Figure 5), the movable cowl 20 is in the retracted position, corresponding to an advanced position in which it ensures aerodynamic continuity with the middle section of the nacelle, and the closure membrane 24 is in the retracted position, a position in which it is at least partly housed in an internal space 200 of the corresponding movable cowl 20, located between an internal wall 202 and an external wall 204 of the movable cowl 20. When the deflection devices 22 are deflection membranes 22 and the movable cowl 20 is in the retracted position, the deflection membranes 22 are in the retracted position, a position in which they are fully housed in the internal space 200 of the corresponding movable cowl 20.

[0061] When the thrust reverser system is in the deployed position (figure 6), the movable cowl 20 is in the deployed position, corresponding to a retracted position, in which it uncovers the deflection devices 22, and the closing membranes 24 are in the deployed position, a position in which they at least partially obstruct the secondary vein 16a. When the deflection devices 22 are deflection membranes 22 and the movable cowl 20 is in the deployed position, the deflection membranes 22 are in the deployed position, a position in which they are arranged at least partially radially outside the envelope formed by the external surface of the movable cowl 20 in the retracted position.

[0062] In this configuration, the action of the closure membranes 24 and the deflection membranes 22 makes it possible to redirect the secondary flow outside the nacelle, towards the front in order to create a counter-thrust. The passage into the deployed position of the closure membranes 24 is obtained by the combined action of the aerodynamic forces generated by the secondary flow circulating in the secondary vein 16a and of deployment devices 26, such as connecting rods, attached to the internal fixed structure 160 of the nacelle.

[0063] The sealing membrane 24 is connected to the deployment devices 26, which in the example are connecting rods 26. Each connecting rod 26 is fixed and articulated to the internal fixed structure 160 of the nacelle. In the example, each connecting rod 26 comprises a first end 160 and a second end 262. Each connecting rod 26 is articulated at the second end 262, the second end 262 being rotatably mounted in a fitting 262a secured to the internal fixed structure 160 of the nacelle 3.

[0064] Each connecting rod 26 is fixed, at the first end 260 opposite the second end 262, to the sealing membrane 24. Thus, during the movement of the latter towards the deployed position visible in FIG. 6, the recoil of the movable cover 20 makes it possible to progressively release the sealing membrane 24, the latter being pushed backwards by the air flow circulating in the secondary vein (represented by the arrow F), at the same time as the movable cover 20 moves backwards. At the same time as the sealing membrane 24 is pushed backwards, it drives the first end 260 of each connecting rod 26, to which it is attached at the front fixing points 240, which causes a rotational movement of each connecting rod 26 towards the rear. This rotational movement drives the first end 260 of each connecting rod 26 towards the internal fixed structure 160, and therefore the deployment of the sealing membrane 24 in the secondary vein.

[0065] The sealing membrane 24 is furthermore fixed, at the level of rear fixing points 242, to one or more fixing elements 168, which are fixed relative to the external fixed structure 162 of the rear section 16 of the nacelle. These fixing elements 168 are arranged downstream of the deflection devices 22. Thus, as visible in FIG. 6, when the thrust reversal system is deployed, the sealing membrane 24 is deployed in the secondary vein, being retained, at the level of the first fixing points 240, by the connecting rods 26 and, at an opposite end, at the level of the second fixing points 242, by the fixing elements 168.

[0066] At the same time as the deployment of the sealing membrane 24, the retraction of the movable cowl towards its retracted position allows the deflection membranes 22 to be released, the latter taking up their deployed position visible in FIG. 6. In this position, the deflection membranes are extended out of the nacelle, the membranes being inflated by the air flow passing through them.

[0067] When the movable cowl, after a thrust reversal phase, returns to its retracted position, the deflection membranes 22 are folded within an internal space 200 of the movable cowl delimited by a part of the internal 202 and external 204 walls. During this folding phase, the passage of the deflection membranes 22 from the deployed position to the retracted position is obtained in particular by pushing back by a front edge 204a of the internal wall 204 of the movable cover 20. Likewise, the closing membrane 24 is folded into the internal space 200 and is pushed back during the folding phase, by a front edge 202a of the internal wall 202 of the movable cover 20.

[0068] Examples of embodiments of deployable membranes 22, 24 according to the invention are described below, in relation to Figures 7 to 19. The deflection membranes 22 and the sealing membranes 24 according to the invention comprise at least one reinforcement 30, 40, as presented in detail below.

[0069] Figures 7 to 11 show examples of embodiments of deflection membranes according to the invention. These deflection membranes 22 are all fixed to a respective peripheral frame 28, fixed relative to the external fixed structure 162 of the nacelle. All the deflection membranes 22 are configured to, when the thrust reverser system 18 is in the reverse jet configuration, channel the secondary flow coming from the secondary vein from an air inlet 222 to an air outlet 224, thus making it possible to eject the redirected flow towards the front of the nacelle to obtain the desired counter-thrust.

[0070] Figures 7 and 8 show a first example of embodiment of deflection membrane 22. The deflection membrane 22 comprises a base 220 in the shape of a U open towards the front, the base 220 extending longitudinally over the entire length of the frame 28. The base 220 forms the air inlet 222 of the deflection membrane 22, the deflection membrane 22 also comprising, as mentioned above, an air outlet 224. The air inlet 220 and the air outlet 222 are connected by sides 226 and a back portion 228.

[0071] In the example of Figures 7 and 8, the deflection membrane 22 comprises several reinforcements 30. Thus, the membrane is equipped with an air outlet reinforcement 300, arranged along the edge 222a of the deflection membrane 22 forming the air outlet, that is to say the front end of the sides 226 and the dorsal part 228. Such a reinforcement makes it possible to stiffen the deflection membrane 22 at the air outlet, thus making it more stable when it is subjected to the turbulence generated by the air flows during the thrust reversal phases. Such a reinforcement can also serve as an aerodynamic deflector.

[0072] The deflection membrane 22 may also be equipped with a base reinforcement 302, such reinforcement forming a belt at or near the attachment of the deflection membrane 22 to the frame 28. Thus, the base reinforcement 302 runs continuously along the sides 226 and the dorsal portion 228.

[0073] The deflection membrane 22 can also be equipped with a back reinforcement 304. Such reinforcement makes it possible to limit the effects linked to the friction caused when the membrane 22 folds, when the latter is pushed back by the movable cover 20.

[0074] Figures 9 and 10 show a second exemplary embodiment of a deflection membrane 22. The deflection membrane 22 comprises a U-shaped base 220 open towards the front, the base 220 extending longitudinally over only a portion of the length of the frame 28, for example over approximately 40 to 60% of the length of the frame 28. The base 220 forms an air inlet 222 of the membrane 22, the deflection membrane 22 also comprising an air outlet 224. The air inlet 220 and the air outlet 222 are connected by flanks 226 and a dorsal portion 228. The deflection membrane 22 further comprises a central strip 230, extending towards the front from the upper portion of the air outlet 224. The central strip 230 is fixed to the frame 28, so to promote expulsion of air passing through the deflection membrane 22 to the sides, and not only forwards as is the case for the deflection membrane 22 of figures 7 and 8.

[0075] The deflection membrane 22 may also be equipped with longitudinal reinforcements 306, running from the base of the dorsal portion 228 to the base of the central strip 230, in a substantially axial direction, along the lateral ends of the central strip 230. Thus, these longitudinal reinforcements 306 make it possible to protect the dorsal portion of the deflection membrane 22 in a manner similar to the dorsal reinforcement 304 mentioned above, and also make it possible to protect the central strip 230 in a manner similar to the air outlet reinforcement, in particular so that it better resists turbulence.

[0076] In the example of Figure 11, the deflection membrane 22 is configured to direct the outgoing air flows laterally. Thus, the deflection membrane 22 of Figure 11 comprises a base 220 forming an open U in a lateral direction, that is to say in a tangential direction relative to the longitudinal axis of the propulsion assembly. For this purpose, the base 220 is connected to the frame 28 over its entire periphery with the exception of one side. longitudinal. The deflection membrane 22 of Figure 11 is equipped with an air outlet reinforcement 300, arranged along the edge 222a of the deflection membrane 22 forming the air outlet. Such a reinforcement makes it possible to stiffen the deflection membrane 22 at the air outlet, thus making it more stable when it is subjected to the turbulence generated by the air flows during thrust reversal phases.

[0077] It will be noted that, whatever the type of deflection membrane 22 described above, the reinforcements 30 are distinct from the frame 28, and, more precisely, from the part of the deflection membrane 22 serving to fix the deflection membrane 22 to the frame 28. Furthermore, as will be seen below, the reinforcements 30 can be attached to the membrane 22 or be at least partially formed by the deflection membrane 22 itself.

[0078] Figures 12 to 15 show examples of the embodiment of reinforcements 30, 40, it being specified that all the examples of the embodiment of reinforcements described in the present application are adapted to the two types of deployable membranes presented, namely the deflection membranes 22 and the sealing membranes 24.

[0079] Whatever the type of reinforcement 30, 40, it can be fixed to the deployable membrane 22, 24 by any suitable means, and in particular by sewing and / or by gluing. Figures 12 to 15 illustrate by broken lines the places suitable for sewing.

[0080] In the example of Figure 12, the reinforcement 30, 40 is simply fixed to the deployable membrane 22, 24, preferably by sewing and / or by gluing.

[0081] In the example of Figure 13, the deployable membrane 22, 24 is arranged so as to form a double fold, this double fold forming the reinforcement 30, 40. The double fold is preferably fixed by sewing and / or by gluing.

[0082] In the example of Figure 14, the deployable membrane 22, 24 is arranged so as to form a double fold on which the reinforcement 30, 40 is fixed, preferably by sewing and / or by gluing.

[0083] In the example of Figure 15, the deployable membrane 22, 24 is arranged to form a simple fold on which the reinforcement 30, 40 is fixed, by sewing and / or by gluing. Alternatively, the simple fold arranged in the deflection membrane can directly form the reinforcement 30, 40, in a manner analogous to the example of Figure 13.

[0084] The reinforcements 30, 40 can also be produced using slender elements, such as slats of suitable rigidity, these elements then being inserted into suitable pockets formed for example by hems provided on the deployable membrane 22, 24.

[0085] Figures 16 to 19 show an exemplary embodiment of the closure membrane 24. Figures 16 and 17 show the closure membrane in its deployed position, respectively seen from the front and seen from the rear. In its deployed position, the closure membrane has a front side 24a oriented towards the front of the propulsion assembly, and a rear side 24b, opposite the front side 24a. In the example of the figures, the closure membrane 24 comprises several reinforcements 40, which make it possible to stabilize the closure membrane both in the retracted position and in the deployed position. Thus, the sealing membrane 24 comprises an internal circumferential reinforcement 400, extending along an internal edge of the sealing membrane 24, and an external circumferential reinforcement 402, extending along an external edge of the sealing membrane 24.

[0086] The sealing membrane 24 further comprises axial reinforcements 404, spaced circumferentially along the sealing membrane 24. Each axial reinforcement 404 extends from the inner edge to the outer edge of the membrane, thus being capable of forming an attachment point 240, 242 to one of the deployment devices 26 on the one hand, and to the external fixed structure 162 on the other hand. The axial reinforcements 404 can be fixed to the sealing membrane 24 in any suitable manner, and for example by gluing and / or by sewing. They can also, as shown in Figure 18, be arranged in pockets 244 arranged on the rear side 24b of the sealing membrane 24. Furthermore, as visible in Figures 16 and 17, all or part of the axial reinforcements can have a general Y shape. In this configuration, the axial reinforcements 404 comprise at a first end a single strand 404a and, at the opposite end, two separate strands 404b.Such a configuration makes it possible to obtain a better distribution of the forces on the sealing membrane 24. Alternatively, other configurations may be provided in which all or part of the axial reinforcements 404 have a different number of strands from one end to the opposite end (for example three strands at one end and one or two strands at the opposite end).

[0087] As visible in Figure 19, the sealing membrane 24 may comprise, near its external circumferential end, a reinforcement forming a deflector 406, making it possible to deflect the air flow towards the deflector membranes 22. In order for the deflector 406 to be correctly oriented when the sealing membrane 24 is in the deployed position, it may be provided that it has a flared shape, or that it is fixed to the sealing membrane 24 only at a radially internal part of the deflector 406, in order to leave the radially external end free, as visible in Figure 18. The deployable membranes 22, 24 described above may be made of a material known to those skilled in the art for this type of application. For example, it may be a non-impregnated fabric, for example aramid fibers. The membranes 22, 24 may also be made using a composite material whose matrix is ​​particularly flexible, for example aliphatic polyurethane, which allows use under varied temperature conditions, in particular lower temperatures in the case of an aliphatic polyurethane membrane than in the case of a silicone membrane. The matrix gives a low flexural recovery capacity and the behavior of the structure obtained is indeed that of a membrane.One of the major properties of the deployable membranes 22, 24 is that they can fold in a perfectly reversible manner (elastically or by fiber sliding), with a very small radius of curvature relative to their surface, and have a very low thickness, for example of the order of 0.1 to 3 mm.

Claims

Claims

1. Thrust reversal system (18) for a nacelle (3) of an aircraft turbojet (2), the thrust reversal system (18) delimiting a secondary vein (16a) for the passage of the secondary flow of the turbojet, the thrust reversal system (18) comprising: at least one movable cowl (20), movable between a retracted position, in which the thrust reversal system is in a direct jet configuration, and a deployed position, in which the thrust reversal system (19) is in a reverse jet configuration; a set of air deflection devices (22);at least one device (24) for closing the secondary flow (16a), movable between a retracted position corresponding to the retracted position of the movable cover (20), in which the closing device is at least partially housed in a space (200) provided in the movable cover (20), and a deployed position corresponding to the deployed position of the movable cover (20), in which the closing device (24) is at least partially deployed in the secondary flow (16a), so as to divert a majority portion of the secondary flow towards the air diversion devices (22);the thrust reverser system (18) comprising at least one deployable membrane (22, 24), the deployable membrane (22, 24) comprising at least one reinforcement (30, 40).

2. The thrust reverser system (18) according to the preceding claim, the deployable membrane (22) forming at least one of the deflection devices (22), the deployable membrane (22) comprising an air outlet (224) and an air outlet reinforcement (300), the air outlet reinforcement (300) extending along a front end of the deployable membrane (22) forming the air outlet (224).;

3. A thrust reversal system (18) according to one of the preceding claims, the deployable membrane (22) forming at least one of the deflection devices (22), the deployable membrane (22) comprising a dorsal portion (228) and a dorsal reinforcement (304) extending in an axial direction along the dorsal portion (228).

4. A thrust reverser system (18) according to one of the preceding claims, the deployable membrane (22) forming at least one of the deflection devices (22), the deployable membrane (22) comprising a base (220) and a base reinforcement (302), extending along a lower end of the base (220).

5. Thrust reversal system (18) according to one of the preceding claims, the deployable membrane (22) forming at least one of the deflection devices (22), the deployable membrane (22) comprising a central strip (230) extending in a longitudinal direction in front of the air outlet (224), and comprising two longitudinal reinforcements (306) extending along the lateral ends of the central strip (230).

6. Thrust reversal system (18) according to one of the preceding claims, the deployable membrane (24) forming at least one of the closure devices (24), the deployable membrane (24) comprising at least one internal circumferential reinforcement (400) and / or at least one external circumferential reinforcement (402).

7. A thrust reversal system (18) according to one of the preceding claims, the deployable membrane (24) forming at least one of the closure devices (24), the deployable membrane (24) comprising one or more axial reinforcements (404), circumferentially spaced from each other, and extending from a radially inner edge to a radially outer edge of the deployable membrane (24).

8. Thrust reversal system (18) according to one of the preceding claims, in which the or at least one of the reinforcements (404) has a number of strand(s) (404a, 404b) which is different from one end to an opposite end.

9. A thrust reverser system (18) according to one of the preceding claims, wherein the reinforcements (30, 40) are attached to the corresponding deployable membrane (22, 24), for example by gluing and / or sewing, or are inserted into pockets provided in the corresponding deployable membrane (22, 24).

10. Nacelle (3) comprising a thrust reversal system (18) according to one of the preceding claims.

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