Thrust reverser comprising at least one deployable deflection membrane with improved attachment

Abstract

The invention relates to a deployable membrane (58) for closing off a secondary flow duct for a thrust reverser of an aircraft propulsion assembly, wherein the membrane extends in a circumferential direction (27) and comprises a membrane extension (70) configured so as to form a strap, a projecting portion of which comprises a first connecting section (70a) for attachment to the membrane, and a second connecting section (70b) intended to be connected to a membrane deployment element (62) located within the reverser, and wherein the strap comprises a transition zone (70c) arranged between its first connecting section (70a) having a first width (L1) in the circumferential direction (27), and its second connecting section (70b) having a second width (L2) strictly smaller than the first width (L1).

Description

[0001] THRUST REVERSER COMPRISING AT LEAST ONE DEPLOYABLE DEFLECTING MEMBRANE WITH IMPROVED ATTACHMENT

[0002] Technical field

[0003] 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.

[0004] State of the prior art

[0005] Thrust reversers are devices 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.

[0006] The grid reversers currently used in the aeronautical sector comprise deflection grids integrated into a fixed or mobile structure of the reverser. The mobile structure of the reverser comprises one or more mobile 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 reversal position.

[0007] In the rearward thrust reverser position, to divert at least part of the secondary flow towards the grilles, the reverser is usually equipped with shutters, which, when deployed, at least partially close the secondary flow. In a known manner, this forces the air of the secondary flow radially outwards, towards the grilles, which then generate the counter-thrust airflow forward.

[0008] The flaps are generally pivotally mounted on the radially inner wall of the movable reverser cowls, this wall delimiting the secondary flow radially outwards. Thus, recesses are provided in this radially inner wall of the reverser cowls in order to receive the shutter flaps in the retracted position, as adopted in direct jet. However, in direct jet, the presence of the recesses and the flaps is a source of aerodynamic disturbances on the secondary flow. In addition, this presence locally limits the installation of an acoustic panel on the radially inner wall of the reverser cowls. To provide a technical solution to these problems, it has been proposed to replace the flaps with one or more deployable membranes for closing the secondary flow. Such a design is for example known from document FR 3 076 864 A1.

[0009] There is nevertheless a need to optimize the design of these sealing membranes, in particular with regard to their connection to membrane deployment elements such as connecting rods or cables, particularly in terms of aerodynamic impact within the secondary vein.

[0010] Statement of the invention

[0011] To meet this need, the invention firstly relates to a deployable membrane for closing a secondary vein, for a thrust reverser of an aircraft propulsion unit, the membrane extending in a circumferential direction, and comprising a membrane extension configured so as to form a strap, a projecting portion of which comprises a first connection part on the membrane, as well as a second connection part intended to be connected to a membrane deployment element provided within the reverser, the strap comprising a transition zone arranged between its first connection part and its second connection part, the first connection part having a first width L1 in the circumferential direction, and the second connection part having a second width L2 strictly less than the first width L1.

[0012] The invention provides a simple and efficient solution, with one, and preferably several membrane extensions that form straps, for its attachment to the membrane deployment elements. In order to limit the aerodynamic impact of each strap in the secondary flow, its second connecting part has a smaller circumferential width, limiting the drag that it generates when it is exposed to the secondary flow, in a direct thrust configuration. This reduction in width of the second connecting part of the strap can thus adapt to a reduced width of the membrane deployment element to which it is connected. Indeed, with the use of sealing membranes rather than more conventional rigid flaps, the membrane deployment elements, such as connecting rods, are only stressed in tension.The intensity of the forces that these connecting rods must withstand is thus lower, so that they can have a smaller dimension, in particular with regard to their width in the circumferential direction. The transition zone implemented on the strap of the invention then makes it possible to achieve a second connecting part also of reduced circumferential width, adapting to the reduced width of its associated connecting rod, with the common consequence of an overall reduction in drag and in the specific consumption of the propulsion unit. The invention is therefore the result of technological research aimed at significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of aircraft (decarbonization).

[0013] Finally, it is noted that the presence of the transition zone on the strap can advantageously be used to stiffen this strap, in order to stabilize it as best as possible in its vibratory environment. The design of this transition zone can be adapted so as to also give it a certain flexibility, in order to prevent it from damaging surrounding elements of the reverser such as the movable cover, or even the deflection edge on the fixed structure. The transition zone of the strap can therefore be designed to provide a satisfactory compromise between a rigidity guaranteeing the blocking of the interface with the connecting rod, and an intrinsic flexibility allowing it to deform, in order not to damage the reverser elements which surround it.

[0014] The invention preferably provides at least one of the following optional technical features, taken alone or in combination.

[0015] Preferably, at least at certain locations of the second connecting part of the strap, the ratio between the first and second widths LI, L2 is greater than three.

[0016] Preferably, the first connecting portion and the second connecting portion of the strap have orthogonal or substantially orthogonal orientations.

[0017] Preferably, the transition zone of the strap is a folding and / or twisting zone of this strap. In particular, the folding lines form preferred zones for giving the strap degrees of freedom of rotation, around these lines. It is noted that the transition zone can form a regular transition, by a regular variation of the two widths L1 and L2, which can in particular be obtained by the shape of a regular tetrahedron.

[0018] Thus, preferably, the transition zone of the strap forms a tetrahedron, preferably regular, and two opposite sides of which correspond to a first and a second fold line respectively forming two degrees of freedom of rotation for the strap.

[0019] This tetrahedral shape, easy to obtain by folding, has proven particularly satisfactory for obtaining the aforementioned compromise between rigidity and flexibility of the strap.

[0020] Preferably, the tetrahedron is filled with a filling material, preferably an elastomeric material, and more preferably a viscoelastic elastomeric material.

[0021] Preferably, the second connecting part of the strap forms a sheath, open or closed laterally.

[0022] Preferably, the strap is made from a strip, possibly doubled or tubular, made in one piece with the membrane or attached to it, and having an identical or substantially identical strip width along the entire length of this strip. This design makes it possible to simplify the design and limit manufacturing costs.

[0023] Preferably, the bandwidth is the same or substantially the same as the length of each of said opposite sides of the tetrahedron.

[0024] The invention also relates to a thrust reverser for an aircraft propulsion unit, the reverser comprising a fixed structure equipped with a radially internal delimiting wall of a secondary vein of the propulsion unit intended to be crossed by a secondary flow, the reverser also comprising a deployable membrane for closing the secondary vein, as described above, as well as a membrane deployment element comprising a first end connected to the radially internal delimiting wall, and a second end connected to the second connecting part of the membrane strap. Preferably, the second connecting part of the strap is mounted on a fixing insert, on which the second end of the membrane deployment element is also mounted. However, a more direct connection, without an insert, is also possible between these two elements, without departing from the scope of the invention.Preferably, the membrane deployment element is a connecting rod or a cable, or a combination of both.

[0025] Preferably, the reverser also comprises a mobile structure comprising at least one reverser cowl having a housing open upstream and delimited between a radially external wall and a radially internal wall of the reverser cowl, the mobile structure being movable in translation relative to the fixed structure along a longitudinal central axis of the reverser, between an advanced direct thrust position and a retracted thrust reversal position in which the retracted radially internal wall of the reverser cowl reveals upstream an opening for passage of the secondary stream towards a flow deflection member, such as a grid or a membrane, at least a portion of the closure membrane being arranged between the flow deflection member and the radially internal wall of the reverser cowl when the mobile structure occupies its advanced direct thrust position, and the strap being located, at its transition zone,sandwiched between the fixed structure and an upstream end of the radially internal wall of the inverter cover.,

[0026] The invention also relates to a nacelle for an aircraft propulsion unit, comprising at least one fan cowl and a thrust reverser as described above.

[0027] Preferably, the membrane extension is configured so as to form a strap, a projecting portion of which comprises a first connection part on the membrane, as well as a second connection part, the membrane deployment element comprising a first end connected to the radially internal delimiting wall, and a second end connected to the second connection part of the strap, via a reversible joining device designed to alternately adopt an association configuration in which it provides a mechanical connection between the second connection part of the strap and the second end of the membrane deployment element, and a dissociation configuration in which it dissociates these two elements.

[0028] First of all, this is advantageous due to the implementation of one or more membrane extensions to form connecting straps with the connecting rods, or other deployment elements of this membrane located in the secondary vein. These straps can advantageously be the elements sandwiched between the fixed structure and the mobile structure in the direct thrust configuration of the reverser, the membrane then remaining outside this vein and thus limiting the drag. Therefore, the invention is the result of technological research aimed at significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of aircraft (decarbonization).

[0029] Furthermore, it is advantageously provided, in association with the end of each strap, a junction device with its deployment rod which allows reversible assembly, that is to say non-destructive disassembly. This design proves particularly advantageous during maintenance operations on the inverter, requiring rapid removal of the membrane.

[0030] Preferably, the reversible joining device is designed so that it can be carried out manually, without tools, the transition from the dissociation configuration to the association configuration, and / or vice versa.

[0031] Preferably, the reversible joining device comprises a locking head and a corresponding housing for receiving the locking head in the association configuration, and the reversible joining device is designed so that the transition from the dissociation configuration to the association configuration is effected by carrying out at least two distinct movements of the locking head relative to its housing, including at least one translational movement and / or at least one rotational movement. The multiplicity of movements advantageously limits the risks of disengagement.

[0032] Preferably, the reversible joining device comprises a buckle, a tongue cooperating with the buckle in the association configuration, as well as a tongue unlocking button, manually actuable preferably in translation and / or in rotation. This type of device is similar to those implemented on safety belts in the field of transport vehicles, and they are particularly proven.

[0033] Preferably, the reversible joining device comprises at least one clip, preferably comprising one or more actuating buttons.

[0034] Preferably, the reversible joining device comprises at least one ball pin passing through the membrane deployment element in the mating configuration.

[0035] Preferably, the reversible joining device comprises a turnbuckle, or a snap hook, preferably of generally rectangular shape.

[0036] Preferably, the reversible joining device forms a fir tree attachment or a dovetail attachment, allowing simple and efficient assembly.

[0037] Preferably, the reversible joining device comprises claws defining between them a housing for a retaining member, preferably of the sausage type, as well as a movable external body for locking the claws, preventing / limiting their separation from each other. This is a kind of mechanical tulip, of a particularly robust and reliable nature.

[0038] According to another possibility, possibly combinable with the previous ones, the reversible joining device comprises a screw-nut assembly, or even several of these assemblies. Other advantages and characteristics of the invention will appear in the detailed non-limiting description below.

[0039] Brief description of the drawings

[0040] The following detailed description refers to the attached drawings in which:

[0041] [Fig. 1] is a schematic half-view in longitudinal section of a propulsion assembly, including a thrust reverser shown in direct thrust configuration;

[0042] [Fig. 2] is a schematic half-view in longitudinal section of the reverser equipping the propulsion assembly shown in Figure 1, with the reverser shown in the direct thrust configuration;

[0043] [Fig. 3] is a schematic half-view of the reverser shown in Fig. 2, shown in the thrust reverser configuration; [Fig. 3A] is a schematic half-view similar to that of the preceding figure, with the reverser being shown in an alternative embodiment;

[0044] [Fig. 4] is a perspective view of the reverser shown in Figures 2 and 3, shown in the direct thrust configuration;

[0045] [Fig. 5] is a perspective view of the reverser shown in Fig. 4, shown in the thrust reverser configuration;

[0046] [Fig. 6] is a schematic view of one of the connecting rods of the reverser shut-off membrane shown in the preceding figures, with the rod shown in a projecting position as adopted in the direct thrust configuration of the reverser;

[0047] [Fig. 7] is a schematic view of the connecting rod shown in Fig. 6, shown in a folded position as adopted in the thrust reverser configuration of the thrust reverser;

[0048] [Fig. 8] is a schematic top view of the secondary flow shut-off membrane of the inverter shown in the preceding figures, representing its assembly with a connecting rod intended for its deployment;

[0049] [Fig. 8A],

[0050] [Fig. 8A'],

[0051] [Fig. 8B],

[0052] [Fig. 8C] are respectively sectional views taken along lines VIIIA-VIIIA, VIIIA'-VIIIA', VII I B-VI I IB and VI IIC-VI IIC of Figure 8;

[0053] [Fig. 9] is a perspective view of part of the assembly shown in the preceding figure;

[0054] [Fig. 10],

[0055] [Fig. 11] are perspective views similar to that of Figure 9, from other angles;

[0056] [Fig. 12] is a schematic longitudinal half-sectional view of a portion of the inverter, showing a membrane strap cooperating with its surrounding inverter elements;

[0057] [Fig. 13] is a sectional view of a reversible joining device shown in Figures 9 to 11, providing the joining between the membrane deployment rod and one end of a strap of this membrane;

[0058] [Fig. 13A] is a sectional view similar to that of Fig. 13, showing an alternative;

[0059] [Fig. 14] is a perspective view similar to that of Fig. 9, according to another preferred embodiment of the invention;

[0060] [Fig. 15] is a schematic top view similar to that of Fig. 8, according to another preferred embodiment of the invention;

[0061] [Fig. 15A],

[0062] [Fig. 15B] are respectively sectional views taken along lines XVA-XVA, XVB-XVB of Figure 15;

[0063] [Fig. 16] is a schematic top view similar to that of Fig. 15, according to another preferred embodiment of the invention;

[0064] [Fig. 16A],

[0065] [Fig. 16B] are respectively sectional views taken along lines XVIA-XVIA, ​​XVIB-XVIB of Figure 16;

[0066] [Fig. 17] is a schematic top view similar to that of Fig. 16, according to yet another preferred embodiment of the invention;

[0067] [Fig. 17A],

[0068] [Fig. 17B], are respectively sectional views taken along lines XVI I A-XVI IA, XVIIB-XVIIB of Figure 17;

[0069] [Fig. 18] is a perspective view of the reversible junction device, similar to that of Fig. 9, according to another preferred embodiment of the invention;

[0070] [Fig. 19] is a perspective view similar to that of Figure 18, from another angle;

[0071] [Fig. 20] is a perspective view of the reversible junction device, similar to that of Fig. 9, according to another preferred embodiment of the invention;

[0072] [Fig. 21] is a cross-sectional view of the reversible junction device shown in the preceding figure;

[0073] [Fig. 22] is a perspective view schematically illustrating the assembly of the reversible junction device shown in Figures 20 and 21;

[0074] [Fig. 23] is a perspective view of the reversible junction device, similar to that of Fig. 20, according to another preferred embodiment of the invention;

[0075] [Fig. 24] is a perspective view schematically illustrating the assembly of the reversible junction device shown in Figure 23;

[0076] [Fig. 25] is a perspective view of the reversible junction device, similar to that of Fig. 20, according to another preferred embodiment of the invention;

[0077] [Fig. 26] is a perspective view schematically illustrating the assembly of the reversible junction device shown in Figure 25;

[0078] [Fig. 27] is a side view of a reversible joining device similar to that of Fig. 25, according to an alternative;

[0079] [Fig. 28] is a perspective view of the reversible junction device, similar to that of Fig. 26, according to another preferred embodiment of the invention;

[0080] [Fig. 29] is a sectional view of the reversible junction device, according to another preferred embodiment of the invention; [Fig. 30] is an exploded perspective view of the reversible junction device, according to another preferred embodiment of the invention;

[0081] [Fig. 31],

[0082] [Fig. 32],

[0083] [Fig. 33], are schematic sectional views of the reversible junction device, according to other preferred embodiments of the invention;

[0084] [Fig. 34] is an exploded perspective view of the reversible junction device, according to another preferred embodiment of the invention;

[0085] [Fig. 35] is a schematic sectional view of the reversible junction device, according to yet another preferred embodiment of the invention.

[0086] Detailed description of embodiments

[0087] Figure 1 shows an aircraft propulsion unit 1, having a longitudinal central axis A1.

[0088] Subsequently, the terms "upstream" and "downstream" are defined relative to a general direction SI of gas flow through the propulsion unit 1, along the axis Al when it generates thrust. These terms "upstream" and "downstream" could respectively be substituted by the terms "front" and "rear", with the same meaning.

[0089] The propulsion unit 1 comprises a turbomachine 2, a nacelle 3 and a mast (not shown), intended to connect the propulsion unit 1 to a wing (not shown) of the aircraft.

[0090] The turbomachine 2 is in this example a twin-spool, dual-flow turbojet engine comprising, from front to rear, a fan 5, a low-pressure compressor 6, a high-pressure compressor 7, a combustion chamber 8, a high-pressure turbine 9 and a low-pressure turbine 10. The compressors 6 and 7, the combustion chamber 8 and the turbines 9 and 10 form a gas generator. The turbojet engine 2 is provided with a fan casing 11 connected to the gas generator by structural arms 12. The nacelle 3 comprises a front section forming an air inlet 13, a middle section which comprises two fan cowls 14 surrounding the fan casing 11, and a rear section 15.

[0091] In operation, an air flow 20 enters the propulsion unit 1 through the air inlet 13, passes through the fan 5 and then divides into a primary flow 20A and a secondary flow 20B. The primary flow 20A flows in a primary gas circulation vein 21A passing through the gas generator. The secondary flow 20B flows in a secondary vein 21B surrounding the gas generator. The secondary vein 21B is delimited radially inwardly by a fixed internal fairing which envelops the gas generator. In this example, the fixed internal fairing comprises a first section 17 belonging to the middle section 14, and a second section 18 extending rearwardly from the first section 17, so as to form a part of the rear section 15. This second section 18 is an integral part of a fixed structure of a thrust reverser which will be described below.This same section will subsequently be called wall 18 of radially internal delimitation of secondary vein 21B.

[0092] Radially outwardly, the secondary vein 21B is delimited by the fan casing 11, and, in the configuration of FIG. 1, by one or more movable reverser cowls 33 forming a part of the rear section 15 of the nacelle 3, and which will be described later. More precisely, between the fan casing 11 and the reverser cowls 33, there is provided an outer shroud 40 of an intermediate casing 42, the latter comprising the aforementioned structural arms 12, the radially outer end of which is fixed to this shroud 40. The latter therefore also participates in delimiting the secondary vein 21B radially outwardly, by being located in the downstream axial extension of the fan casing 11.

[0093] The nacelle 3 therefore comprises a thrust reverser 30 centered on the axis A1 and comprising on the one hand a fixed structure 31 secured to the fan casing 11, and on the other hand a structure 29 movable relative to the fixed structure 31. The fixed structure 31 comprises for example a front frame 46 which connects it fixedly to the fan casing 11, preferably via a knife-edge flange assembly located downstream of the outer shroud 11. This front frame 46 contains a profiled aerodynamic part called a deflection edge 46B, which guides the flow in an inverted jet.

[0094] The fixed structure also comprises a plurality of deflection grids 32 arranged adjacent to each other around the axis A1, in a circumferential direction of the reverser 30 and the propulsion assembly 1. These grids 32 thus form flow deflection members to generate the counter-thrust. In this regard, it is noted that this flow reversal function can alternatively or simultaneously be achieved using a flexible structure, of the membrane / textile type.

[0095] Furthermore, the mobile structure 29 comprises the aforementioned mobile reverser cowls 33, for example two cowls 33 each extending over an angular amplitude of approximately 180°. This configuration with two cowls 33 is particularly well suited in the case of a nacelle design in which the cowls / walls 18 are also mounted articulated, the reverser 30 then having a so-called “D-shaped” architecture, known by the English name “D-Duct”. In this architecture, the cowls 18, 33 are connected so as to open / close simultaneously during maintenance operations on the engine. However, other architectures are possible, such as for example a so-called “C-shaped” architecture, known by the English name “C-Duct”, or even a so-called “O-shaped” architecture, known by the English name “O-Duct”.

[0096] Each reverser cowl 33 comprises a radially external wall 50 forming an external nacelle aerodynamic surface, as well as a radially internal wall 52 participating in the delimitation of the secondary vein 21B radially outwards. This wall 52 is located in the downstream continuity of the deflection edge 46B. The two walls 50, 52 define a housing 54 open axially at the upstream end of the reverser cowl 33.

[0097] Figure 1 shows the reverser 30 in a forward thrust configuration, called “direct jet”, corresponding to a standard flight configuration. In this configuration, the cowls 33 of the mobile structure 29 are in a closed position, called the advanced thrust or “direct jet” position, in which these reverser cowls 33 are supported on the fixed structure 31, in particular on the deflection edge 46B forming an integral part of the latter. Indeed, in the direct thrust configuration, the upstream end 52a of the radially internal wall 52 of each cowl 33 is in axial support against the deflection edge 46B.

[0098] The mobile structure 29 is thus movable in translation relative to the fixed structure 31 along the axis A1 of the reverser, between the forward direct thrust position shown in FIG. 1, and a retracted thrust reversal position which will be described later. In the forward direct thrust position of the mobile structure 29, the deflection grids 32 are arranged in the housing 54 of the reverser cowls 33, being isolated from the secondary vein 21B by the radially internal wall 52 of these sliding reverser cowls 29. This wall 52, forming the external wall of the secondary vein, is also called an acoustic internal panel.

[0099] This direct thrust configuration is also shown in Figures 2 and 4, while the rearward thrust reversal position of the mobile structure 29 is shown in Figures 3, 3A and 5. In Figure 3, it is shown that the rearward internal acoustic panel 52 of the reverser cowls reveals upstream a passage opening 56 of the secondary vein 21B towards the deflection grilles 32. The opening 56 is therefore also delimited upstream by the deflection edge 46B, which flares radially outwards going towards the rear, to delimit an air flow intended to pass through the grilles 32 when the mobile system is in this rearward thrust reversal position. In other words, the deflection edge 46B gradually moves away from the axis A1 from front to rear, to guide / deflect the air towards the grilles 32 in the thrust reversal configuration.

[0100] In order to divert at least a portion of the secondary flow 20B toward the passage opening 56 defined axially between the deviation edge 46B and the upstream end 52a of the radially inner wall 52 of each cover 33, the inverter 30 comprises one or more sealing membranes 58. Subsequently, an embodiment will be described in which a single membrane 58 is associated with each inverter cover 33 while having an identical or similar angular amplitude, but it remains conceivable to provide several circumferentially adjacent membranes associated with each cover 33. Similarly, only the cooperation between a membrane 58 and its associated cover 33 will be described below, it being understood that this cooperation is identical or similar for all the covers of the inverter 33.

[0101] The membrane 58 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 membrane 58 may also be made using a composite material whose matrix is ​​particularly flexible, for example aliphatic polyurethane, which allows use under different 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 bending recovery capacity and the behavior of the structure obtained is indeed that of a membrane. One of the major properties of this membrane 58 is that it can bend in a perfectly reversible manner (elastic or by fiber sliding) with a very small radius of curvature relative to its surface, and to have a very small thickness, for example of the order of 0.1 to 3 mm.For information purposes, it is observed that this membrane 58 behaves like a boat sail or a parachute / flying wing when it is pressurized.

[0102] The sealing membrane 58 comprises a first end 58a, or rear end, connected to a rear frame 60 for supporting the grids 32, this support being annular or in the form of an annular section in fact connecting together the rear ends of several adjacent grids. The membrane 58 also comprises a second end 58b, or front end, connected to the radially internal delimiting wall 18 of the secondary vein, in a manner specific to the invention which will be described later.

[0103] Furthermore, as can be seen in Figures 1, 2 and 4, when the mobile structure 29 occupies its forward direct thrust position, at least a portion of the closure membrane 58 is arranged radially between the deflection grids 32 and the radially internal wall 52 of the reverser cover 33, in the housing 54. Preferably, the portion of the membrane 58 which is located in this housing 54 of the reverser cover 33, radially covers the entire length of the grids 32. Preferably, this is almost the entire membrane, only connecting straps provided at the front end 58b of the membrane being clamped between the upstream end 52a of the wall 52, and the deflection edge 46B.

[0104] Also, as can be seen in Figure 3, when the mobile structure 29 moves and occupies its rearward thrust reversal position at the end of this movement, the sealing membrane 58 is partly in abutment against the upstream end 52a of the radially internal wall 52 of the reverser cowl, thus corresponding to the acoustic panel. More precisely, during the rearward movement of the mobile structure 29, the membrane 58 slides on this upstream end 52a of the radially internal wall 52.

[0105] In the rearward thrust reversal position of Figure 3, the membrane 58 is therefore in axial support downstream against the upstream end 52a. It should be noted that depending on the extent of the axial travel of the reverser, the membrane 58 may no longer be in contact with the internal acoustic panel 52 in the fully deployed position of the reverser, where the cowl 33 is in its most rearward position. Such a configuration is shown in Figure 3A, in which it is clearly shown that the membrane 58 is located upstream and at a distance from the upstream end 52a of the wall 52 of the reverser cowl. The option with contact corresponds to a minimized travel of the reverser, while the option without contact generally corresponds to a smoother membrane shape in reverse jet, therefore more efficient from an aerodynamic point of view.

[0106] Thus, the part of the membrane 58 which is located radially outwards relative to its support zone on the wall 52 closes off a part of the upstream axial opening of the housing 54, while the other part located radially inwards closes off at least a part of the secondary vein 21B, thereby diverting at least a part of the secondary flow 20B towards the passage opening 56 in the direction of the grids 32.

[0107] In another preferred embodiment not shown, the radially external attachment of the membrane 58 can be carried out on the radially external wall 50 of the sliding cover 33. Thus, in the direct pushing position, the membrane 58 is housed in the housing 54 by being folded radially on either side of the grids 32, with a fold defined at the level of the contact zone with the downstream end 60a of the rear grid support frame 60.

[0108] The thrust reverser also comprises deployment elements 62 of the membrane 58, distributed circumferentially in relation to the axis A1 of the reverser. These deployment elements 62, arranged in the secondary vein 21B, can take the form of connecting rods and / or cables. In the case of cables, these can be elastic, for example using Kevlar cables, and these same cables can be put under tension when the sliding cowl 33 is closed.

[0109] In the preferred embodiment shown, the membrane deployment elements 62 are connecting rods, each comprising a first end 62a mounted on the wall 18, preferably via a pivot or ball joint 64, shown in more detail in Figures 6 and 7. This connection 64 can be made using a fitting 66 fixed to the fixed wall 18 and cooperating with the first end of connecting rod 62a.

[0110] As mentioned previously, the connecting rods 62 are spaced circumferentially from each other within the secondary vein 21B, and their number can for example vary from two to ten in association with the same membrane.

[0111] Each connecting rod 62 is designed to move from a radially projecting position in the secondary vein 21B, a position shown in FIGS. 2, 4 and 6 and adopted when the mobile structure 29 occupies its forward direct thrust position, to a downstream folded position, shown in FIGS. 3, 5 and 7 and adopted when the mobile structure 29 occupies its rearward thrust reversal position. In the projecting position, each connecting rod 62 can adopt a radial or substantially radial orientation relative to the axis A1, while in the folded position, each connecting rod 62 can adopt an axial or substantially axial orientation.

[0112] Elastic means, called elastic return means 68, tend to incline each connecting rod 62 towards its folded / lying position of FIG. 7, in particular when the connecting rod is in its projecting position corresponding to the flight position of the reverser. Thus, at the start of deployment of the reverser, each connecting rod 62 exerts on the membrane 58 a rearward and downward thrust which pulls it into the vein so that the flow which rushes into the cavity 54 at the start of transit does not jam the membrane in this cavity 54 of the fan cowl 33.

[0113] The second end 62b of each connecting rod 62, opposite the first end 62a, is connected to the second end 58b of the membrane 58, according to a design specific to the invention.

[0114] It is noted that the connecting rods 62 are axially positioned so that the trajectory of their end 62b is tangent or substantially tangent to the inner surface of the acoustic panel 52 in its front part, or so that the trajectory is downward in the vein.

[0115] With reference to Figures 8 to 13, the reversible connection is shown between the membrane 58 extending in a circumferential direction T1 corresponding to the circumferential direction of the inverter relative to the axis A1, and the second end 62b of one of the connecting rods 62. It is noted that an identical or similar connection can be implemented for each connecting rod 62 intended for the deployment of the membrane. Consequently, only one of these connections will be described below.

[0116] Moreover, it is recalled that if the membrane 58 extends well in the circumferential direction T1, whether when it is folded in the direct thrust configuration, or when it is deployed in the reverse thrust configuration, the deployment of this membrane 58 is carried out in a generally radial manner.

[0117] Along the circumferential direction T1, the front end 58b of the membrane 58 comprises several spaced apart front membrane extensions, each configured to form a strap 70. In the figures, only one of these straps is shown, but they all have an identical or similar design. Each strap 70 has, by nature, a flexible character which allows it to deform during the phases of movement of the reverser between the direct thrust configuration and that of thrust reversal. Nevertheless, this deformation is preferably carried out with each strap 70 remaining in a longitudinal plane of the reverser, and passing through its axis A1.

[0118] The strap 70 extends axially forwardly within the front end of the membrane 58b, either by being made in one piece with this membrane, or by being attached to it as shown diagrammatically in FIG. 8. As a result, a rear part of the strap 70 is superimposed on a membrane body, corresponding to the active part thereof, intended to fulfill the function of closing the secondary flow in the thrust reversal configuration. The strap can be fixed in any known manner, preferably by sewing and / or gluing this strap to the membrane body.

[0119] In this preferred embodiment, the strap is made from a strip, of tubular design in the sense that its section follows a closed contour. Although the strap 70 has several parts of different shapes and / or orientations, it is here preferentially made from a strip having an identical or substantially identical strip width all along this strip. The aforementioned strip width corresponds to the width of the strip when it is flattened, and two layers of textile therefore rest on top of each other, with their lateral edges connected two by two, as has been shown schematically in FIG. 8A'. The different shapes and / or orientations of the parts of the strap, which will be described below, are obtained by folding and / or twisting this initial strip of constant or substantially constant width, and preferably only by folding.

[0120] More specifically, with regard to its forwardly projecting portion, the strap 70 comprises a first connecting part 70a intended to be connected to the front end 58b of the membrane, in the manner explained above. It also comprises a second connecting part 70b, intended to be connected to the second connecting rod end 62b, using a reversible joining device 72 which will be described later. In addition, a transition zone 70c is arranged between the two connecting parts 70a, 70b.

[0121] The first connecting part 70a is substantially in the surface continuity of the membrane body, while still being offset from the latter by a very small distance corresponding to the thickness of the membrane body. The first connecting part 70a therefore has a flattened shape extending in the circumferential direction T1, with a first circumferential width L1 which is significant, preferably constant, and corresponding to the aforementioned band width. This first width L1 has been identified in FIGS. 8 and 8A'.

[0122] The second connecting part 70b is in the continuity of the connecting rod 62, which may have a non-circular profile, but on the contrary a cross-section elongated in the axial direction, for example of oval, oblong, or similar shape. This axially elongated section makes it possible to benefit from a reduced circumferential width of the connecting rod, in order to limit the drag on the secondary flow in the direct thrust configuration. Also, to correspond to this connecting rod profile and also participate in limiting the drag in the secondary vein 21B, the second connecting part 70b also has a section of elongated shape in the axial direction, and narrowed in the circumferential direction T1, with a second small circumferential width L2.This second width L2 is preferably scalable along the second connecting part 70b, but it always remains strictly less than the width L1 of the first connecting part 70a of the strap. In the case where the first width L1 would also be scalable, then the largest width L2 along the second connecting part 70b would preferably remain strictly less than the smallest width L1 along the first connecting part 70a of the strap.

[0123] The second width L2 has been identified in Figures 8 and 8C and 13. In this regard, it is noted that this width L2 increases up to its connecting end to the connecting rod 62.

[0124] The ratio between the first and second widths L1, L2 is therefore here scalable, and it can be greater than three at least at certain locations of the second connecting part 70b. The transition zone 70c, arranged between the two connecting parts 70a, 70b, is obtained by simple folding of the textile strip, with multiple fold lines until a tetrahedron shape, preferably regular, is obtained. The tetrahedron 74 defined by the strap is preferably filled with a filling material 76, for example a viscoelastic elastomer material.

[0125] The tetrahedron 74 then has two opposite sides 78, 80, corresponding to a first and a second fold line of the strap. These fold lines 78, 80, at which the textile layers of the strip are preferably flattened on top of each other and fixed by sewing and / or gluing, respectively form two degrees of freedom of rotation for the strap 70. The latter is then stiffened by the presence of this transition zone 70c, while having a certain flexibility due to the presence of these fold lines 78, 80.

[0126] Furthermore, it is noted that the length of these two opposite sides 78, 80 is identical or substantially identical to the aforementioned strip width, therefore also corresponding to the first width L1 of the first connecting part 70a of the strap 70.

[0127] As an indication, it is noted that the succession of parts 70a, 70c, 70b can easily be obtained from a tubular strip, which is first folded orthogonally to the direction of the length of this strip, in order to form the first fold line 78. Then, at a distance from the first fold line 78, a new fold is made orthogonally to the previous one, which makes it possible to form the second fold line 80, and to define between these two lines 78, 80 the tetrahedral shape of the transition zone 70c. Thanks to this design, the first connecting part 70a of the strap and its second connecting part 78 have orthogonal or substantially orthogonal orientations, just as the two fold lines 78, 80 are preferably orthogonal or substantially orthogonal to each other.

[0128] In the direct thrust configuration shown schematically in Figure 12, the first fold line 78 is oriented in the circumferential direction T1, in order to allow a break in the strap 70 between the first connecting part 70a located in the cover housing 54, and the transition zone 70c axially sandwiched between the deflection edge 46B and the upstream end 52a of the wall 52 of the movable cover. Moreover, certain faces of the tetrahedron may be slightly deformed due to their contact with these elements 46B, 52a. Still in the direct thrust configuration shown schematically in Figure 12, the second fold line 80 is oriented axially, or substantially axially.

[0129] As mentioned above, the end of the second connecting part 70b is connected to the second connecting rod end 62b, using a reversible joining device 72.

[0130] This end of the second connecting part 70b forms a sheath 82, referenced in figure 13, and laterally closed due to the tubular nature of the strap 70.

[0131] The joining device 72, due to its reversible nature, is configured to alternately adopt an association configuration (figure 13) in which it provides a mechanical connection between the sheath end 82 of the second connecting part 70b and the second connecting rod end 62b, and a dissociation configuration in which it dissociates these two elements 82, 62b, thus allowing their disengagement by relative displacement.

[0132] Here, the joining device 72 comprises one or more screw-nut assemblies 86, but also a fixing insert 88 on which are mounted both the sheath 82 of the second connecting part 70b, and the second connecting rod end 62b.

[0133] To do this, the fixing insert 88 is hollow, and housed in the sheath 82. Externally, this sheath is covered with a ring 90 allowing the sheath to be crimped between the ring 90 and the insert 88. Moreover, the internal shape of the ring can be conical so as to ensure that when the connecting rod is tensioned, the tightening of the sheath 82 is accentuated in cooperation with the insert 88. In addition, the second end of the connecting rod 62b is housed in the insert 88, and all of the elements 90, 82, 88, 62b are then crossed by the reversible screw-nut assembly 86.

[0134] It is sufficient to disassemble this assembly 86 to obtain the dissociation configuration of the joining device 72, configuration in which the two elements 82, 62b are dissociated and can be separated from each other. The nut of the assembly 86 may have a barrel in order to reinforce the shearing function provided by this assembly. For aerodynamic reasons, the head of the screw and the nut may be entirely or partially embedded in corresponding counterbores of the ring 90, forming the external element of this joining device 72. Figure 13A shows an alternative, with the second connecting rod end 62a forming a yoke in which all the other elements 82, 88, 90 are inserted, and the two heads of the screw and the nut being housed at least partly in counterbores on the ears of this yoke.

[0135] Furthermore, it is noted that the screw-nut assembly 86 can simply fulfill the function of a shearing member as shown in FIG. 13, or this assembly 86 can also be tightened along its axis in order to grip the aforementioned elements 90, 82, 88, 62b, in particular to tighten the ring 90 against the sheath 82.

[0136] It is noted that several of these screw-nut assemblies 86 can be arranged along the second connecting rod end 62b, without departing from the scope of the invention.

[0137] Figure 14 shows that the same or similar design may be implemented when the membrane deployment element 62 is a cable, with the end of the cable comprising a crimped terminal 92, cooperating with the reversible joining device 72.

[0138] In another embodiment shown in Figures 15 to 15B, the projecting portion of the strap 70 is a single strip, which should be folded after the transition zone 70c, in order to form the sheath of the second connecting portion 70b. This sheath, visible in Figure 15B, therefore has a laterally open section. This single-layer strap, therefore flat, covers a portion of the membrane body before extending projecting from it, as can be seen in Figures 15 and 15A.

[0139] In another preferred embodiment shown in Figures 16 to 16B, the projecting portion of the strap 70 is also tubular in shape, but with two textile portions attached to one another, at their respective lateral edges. This strap can be obtained with a portion extending in one piece with the membrane body, covered by a single-layer flat strip, fixed to the aforementioned portion and to the membrane body.

[0140] In yet another preferred embodiment shown in Figures 17 to 17B, the projecting portion of the strap 70 is made in one piece with the membrane, in the form of a single-layer flat strip lying in perfect continuity with the membrane body. Just as in the embodiment of Figures 15 to 15B, the strip should be folded back on itself after the transition zone 70c, in order to form the sheath of the second connecting portion 70b. Here too, this sheath visible in Figure 17B, is also open laterally.

[0141] In the embodiment of Figures 18 and 19, the joining device still includes the insert 88, but the sleeve 82 and the second connecting rod end 62b are mounted on this insert at two points distinct from it, respectively by two screw-nut assemblies 86. Moreover, for the assembly of the sleeve 82 corresponding to the end of the second connecting part 70b of the strap 70, the screw-nut assembly 86 dedicated to it no longer passes through the clamping ring 90. The latter in fact cooperates with the insert 88 still to crimp this second connecting part 70b, but at a point on the insert different from that passed through by the screw-nut assembly 86.

[0142] In the embodiment of Figures 20 to 22, the reversible joining device 72 is designed so as to be able to manually, without tools, change from the dissociation configuration to the association configuration, and / or vice versa. To do this, the second connecting rod end 62b is secured to a rod 94 which is extended in its own direction, this rod carrying a locking head 96, here grooved or star-shaped with a number of branches which can vary.

[0143] In the association configuration shown in Figures 20 and 21, the locking head 96 is received in a housing 98 made in the insert 88. It is possible for the head 96 to access this housing 98, by passing through a passage orifice 100 of section identical or similar to that of the head 96. This orifice 100 is also made through the insert, and it opens into the housing 98. Thus, the design of the joining device 72 is such that the transition from the dissociation configuration to the association configuration is effected by carrying out two distinct movements of the locking head relative to its housing. With reference primarily to Figure 22, this first involves a relative translational movement of the locking head 96 through the passage orifice 100 in the insert, with the teeth / grooves of this head aligned with corresponding recesses 102 of the passage orifice 100.

[0144] Once the orifice 100 has been passed through and the head 96 is fully located in the housing 98, this head is rotated relative to the housing along an axis corresponding to that of the rod 94, in order to misalign the aforementioned teeth and hollows, with the aim of obtaining the locking corresponding to the association configuration. This configuration is for example secured by an elastic system, such as a spring 104 housed in the insert and which presses the locking head 96 against the bottom of the housing 98.

[0145] It is noted that the dissociation configuration is obtained by carrying out the reverse operations, preferably still without a tool but by carrying out the aforementioned relative movements between the second connecting rod end 62a, and the insert 88. Consequently, in this dissociation configuration, the insert 88 remains fixed to the sheath 82 of the strap, in any manner and preferably according to a solution of the type described previously. The dissociation between the strap 70 and the connecting rod 62 is therefore carried out at the level of the insert 88, which is dissociated from the second connecting rod end 62b.

[0146] Figures 23 and 24 show another similar embodiment, in which the locking head 96 is a protuberance, for example in the shape of a ball or a portion of a ball. The housing 98 of the protuberance 96 is no longer located in the continuity of the passage orifice 100 in the direction of introduction of the protuberance through this orifice. Indeed, the housing 98 communicates laterally with the passage orifice 100.

[0147] Thus, the design of this joining device 72 is such that the transition from the dissociation configuration to the association configuration is firstly effected by carrying out a relative translational movement of the locking head 96 through the passage orifice 100 in the insert, the respective diameters of these elements allowing such an introduction in the direction of the rod 94. Then, another relative translation is carried out, in an orthogonal direction leading to a relative lateral movement, as has been shown diagrammatically in FIG. 24. This causes the locking head 96 to penetrate into the housing 98, into which another passage orifice 106 opens parallel to the orifice 100 and receiving the rod 94, but having a diameter smaller than that of the protuberance forming the locking head 96.

[0148] The association configuration is also secured here by the elastic system 104, which presses the locking head 96 against the bottom of the housing 98, into which the other passage orifice 106 of reduced section, also made in the insert 88, opens.

[0149] Figures 25 and 26 show another similar embodiment, in which the locking head 96 is still a protuberance, for example in the form of a cylinder with an axis orthogonal to that of the rod 94, in order to jointly form a T. This cylinder 96 may have one or more flats to improve the mechanical connection obtained, in the association configuration. Here too, the housing 98 communicates laterally with the passage orifice 100, and the other passage hole 106 is also provided. The difference lies in the fact that the passage orifice 100 is open laterally on the insert 88, and no longer only axially in the direction of the rod 94.

[0150] Consequently, with this joining device 72, the transition from the dissociation configuration to the association configuration is firstly effected by carrying out a relative translational movement of the locking head 96 and a portion of the rod 94 through the passage orifice 100, laterally in the insert 88 in a direction orthogonal to those of the cylinder 96 and the rod 94. Then, another relative translation is carried out, in an orthogonal direction, parallel to the axis of the cylinder 96, and leading to a relative lateral movement as has been shown diagrammatically in FIG. 26. This causes the locking head 96 to penetrate into the housing 98, into which the other passage orifice 106 parallel to the orifice 100, and receiving the rod 94, therefore opens.

[0151] The association configuration is also secured here by the elastic system 104, which presses the locking head 96 against the bottom of the housing 98, into which the other passage orifice 106 of reduced section opens.

[0152] Figure T1 represents an alternative for securing the association configuration. It comprises a clamping nut 108 mounted on the rod 94, and can be tightened on a surface of the insert 88 in order to press the locking head 96 into the bottom of the housing 98. As an indicative example, it is noted that a wire (not shown) ensuring the braking of the nut can be implemented on this nut 108.

[0153] This solution of replacing the spring 104 with the clamping nut 108 can obviously concern all the preferred embodiments, as well as their alternatives.

[0154] With reference to Figure 28, the preferred embodiment shown therein differs only from the previous one in that the passage orifice 100 is no longer parallel to the other passage orifice 106, but it has a certain inclination according to which the rod 94 and the cylinder 96 must be inclined to penetrate laterally into this orifice 100. Then, before the last relative lateral translation between the cylinder and the insert, an intermediate relative displacement must be carried out, namely a rotation of the cylinder 96 and the rod 94 around the axis of the cylinder, by a value corresponding to that of the inclination between the two passage orifices 100, 106. This combination of three successive relative displacements thus constitutes an additional safety to avoid disengagement of the joining device, while requiring no tool to ensure its engagement.

[0155] Among the solutions not requiring a tool, Figure 29 proposes a clip 110 mounted inside the second end of connecting rod 62b, and having at its ends two actuating buttons 112 passing through corresponding orifices 114 through the connecting rod 62. These actuating buttons 112 can be elastically constrained radially inwards to return towards the inside of the connecting rod, and, when they are arranged in correspondence with orifices 116 of the insert 88, they redeploy radially outwards by penetrating these orifices 116. This forms a lock making it possible to achieve the association configuration. A reverse solution is obviously conceivable, in which the clip 110 would be mounted on the insert 88. In the embodiment of FIG. 30, the reversible joining device ni comprises a loop 120 provided on the insert 88 as well as a tab 122 provided on the second connecting part 70b, or vice versa.In the association configuration shown in Figure 30, the two elements 120, 122 cooperate with each other in the manner of a safety belt of a transport vehicle. A push button 124, actuable in translation and allowing the tongue to be unlocked, is located on the insert 88. But it could alternatively be an unlocking button actuable in rotation, as on the safety belts of commercial aircraft. It is noted that this solution, also usable without an assembly / disassembly tool, could be implemented without an insert 88, but directly on the connecting rod 62 and the strap 70.

[0156] Yet another solution is shown in Figure 31, with the second connecting part 70b of the strap forming, at its end, a loop 126 connecting it to a connecting part 128 in the form of a yoke. This part receives the insert 88 or directly the second end of the connecting rod 62a, which is perforated with holes 130 like the yoke. When the holes 130 are aligned, for example along two parallel lines, ball pins 132 can be introduced into these holes in order to lock the elements using balls 134 forming stops, and making it possible to obtain the association configuration (not shown). Indeed, in this configuration, the pins 132 pass through the different lines of holes of the elements 128, 88, and they can only be extracted by exerting pressure on the balls 134, in order to temporarily retract them and allow the pins to be disengaged.

[0157] Figure 32 shows another preferred embodiment of the invention, with the second connecting part 70b forming at its end a sort of sausage / rope 136. In the association configuration shown in this figure, the sausage 136 is trapped in a housing 138 defined between elastic claws 140. There is also provided a movable outer body 142 for locking the claws, which covers these claws 140 thus preventing them from moving apart from each other. This device 72 then operates in the manner of a mechanical tulip, so that when the outer body 142 is brought into a retracted axial position moving it away from the claws 140, the latter can deform and thus allow the insertion or extraction of the sausage 136 between the separated ends of these claws. The outer body 142 is returned to the locking position by an elastic means of the spring type 144.

[0158] Figure 33 shows a preferred embodiment based on the use of a carabiner 146 between the loop 126 at the second connecting end 70b of the strap, and the insert 88 or directly the second connecting rod end. A C-shaped carabiner is possible, but a rectangular shape remains preferred. The dissociation can be effected by the carabiner 146 at the strap loop 126 as shown in Figure 33, but alternatively, this could be achieved at the insert 88 or the second connecting rod end.

[0159] According to yet another preferred embodiment shown in Figure 34, the reversible joining device 72 forms a fir tree attachment 148 or a dovetail attachment between the insert 88 and the second connecting rod end 62b. The assembly is carried out by simple sliding between the teeth of the two fir trees, in the manner of the assembly of certain turbomachine blades. The association configuration, shown in Figure 34, can be locked by one or more screws 150 passing through the elements 88, 62b, preferably in an at least partially embedded manner so as to limit the aerodynamic disturbances of the secondary flow, in the direct thrust configuration of the reverser.

[0160] Finally, Figure 35 shows another preferred embodiment of the invention, implementing a turnbuckle 152 between the insert 88 and the second end of the connecting rod 62. The turnbuckle 152 has a clamping hole 154 allowing the barrel to be rotated, and thus tightening / loosening the insert 88 relative to the second end of the connecting rod 62.

[0161] 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, and the scope of which is defined by the appended claims. For example, the thrust reverser 30 may alternatively have a “C” or “O” architecture. Furthermore, the membranes specific to the invention may coexist with conventional grids within the reverser. Furthermore, all the features disclosed above, in the various preferred embodiments and their alternatives, are combinable with each other. Moreover, it is noted that in all the figures which have been described above, the elements which bear the same numerical references correspond to identical or similar elements.

Claims

CLAIMS 1. Deployable membrane (58) for closing a secondary vein, for a thrust reverser (30) of an aircraft propulsion unit, the membrane extending in a circumferential direction (27), characterized in that it comprises a membrane extension (70) configured so as to form a strap, a projecting portion of which comprises a first connection part (70a) on the membrane, as well as a second connection part (70b) intended to be connected to a membrane deployment element (62) provided within the reverser, the strap comprising a transition zone (70c) arranged between its first connection part (70a) and its second connection part (70b), the first connection part (70a) having a first width (L1) in the circumferential direction (27), and the second connection part (70b) having a second width (L2) strictly less than the first width (L1).

2. Membrane according to claim 1, characterized in that the first connecting part (70a) and the second connecting part (70b) of the strap have orthogonal or substantially orthogonal orientations.

3. Membrane according to claim 1 or 2, characterized in that the transition zone (70c) of the strap is a folding and / or twisting zone of this strap.

4. Membrane according to any one of the preceding claims, characterized in that the transition zone (70c) of the strap forms a tetrahedron, preferably regular, and two opposite sides of which correspond to a first (78) and a second fold line (80) respectively forming two degrees of freedom of rotation for the strap (70).

5. Membrane according to any one of the preceding claims, characterized in that the second connecting part (70b) of the strap forms a sheath (82), open or closed laterally.

6. Membrane according to any one of the preceding claims, characterized in that the strap (70) is made from a strip, possibly doubled or tubular, made in one piece with the membrane (58) or attached to it, and having an identical or substantially identical strip width all along this strip.

7. Membrane according to the preceding claim, combined with claim 4, characterized in that the bandwidth is identical or substantially identical to the length of each of said opposite sides of the tetrahedron.

8. Thrust reverser (30) for an aircraft propulsion unit, the reverser comprising a fixed structure (31) equipped with a radially internal delimiting wall (18) of a secondary vein (21B) of the propulsion unit intended to be crossed by a secondary flow (20B), the reverser also comprising a deployable membrane (58) for closing the secondary vein according to any one of the preceding claims, as well as a membrane deployment element (62) comprising a first end (62a) connected to the radially internal delimiting wall (18), and a second end (62b) connected to the second connecting part (70b) of the strap of the membrane (58).

9. Reversal according to claim 8, characterized in that the reversal also comprises a mobile structure (29) comprising at least one reversal cover (33) having a housing (54) open upstream and delimited between a radially external wall (50) and a radially internal wall (52) of the reversal cover (33), the mobile structure being movable in translation relative to the fixed structure along a longitudinal central axis (A1) of the reversal, between an advanced direct thrust position and a retracted thrust reversal position in which the retracted radially internal wall (52) of the reversal cover reveals upstream an opening (56) for passage of the secondary stream (21B) towards a flow deflection member (32),at least a portion of the sealing membrane (58) being arranged between the flow deflection member (32) and the radially internal wall (52) of the reverser cover (33) when the mobile structure occupies its advanced direct thrust position, and the strap (70) being, at its transition zone (70c), clamped between the fixed structure (31) and an upstream end (52a) of the radially internal wall (52) of the reverser cover (33)., 10. Nacelle (3) for an aircraft propulsion unit, comprising at least one fan cowl (14), as well as a thrust reverser (30) according to any one of claims 8 and 9.

Images