THRUST REVERSER COMPRISING AT LEAST ONE DEPLOYABLE MEMBRANE, HAVING IMPROVED DEPLOYMENT MEANS

Abstract

The invention relates to a thrust reverser for an aircraft propulsion unit, comprising a membrane (58) for closing the secondary flow path (21B), a first end of which is connected to the fixed structure (31) of the reverser, this membrane bearing against the upstream end (52a) of a radially internal wall (52) of a mobile reverser cowl and exerting on this upstream end (52a) a first force (70a) with a first axial component (72a) oriented downstream. In addition, the reverser is configured so that when the mobile structure (29) occupies its retracted thrust reversal position, a membrane deployment member (62), such as a cable, exerts on a fixing or guiding element (64) secured to the mobile cowl, a second force (70b) with a second axial component (72b) oriented upstream. Figure for the abstract: Fig. 6

Description

Title of the invention: THRUST REVERSER COMPRISING AT LEAST ONE DEPLOYABLE MEMBRANE, HAVING IMPROVED DEPLOYMENT MEANS 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 prior art

[0002] Thrust reversers are devices for diverting the airflow passing through the propulsion unit forward, so as to shorten landing distances and limit the stress on the brakes on the landing gear.

[0003] 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.

[0004] In the rearward thrust reversal 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 vein. In a known manner, this forces the air of the secondary flow radially outwards, towards the grilles, which then generate the counter-thrust air flow towards the front.

[0005] 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.

[0006] To provide a technical solution to these problems, it has been proposed to replace the shutters with one or more deployable membranes for closing the secondary vein. Such a design is known, for example, from document FR 3 076 864 AL

[0007] There remains, however, a need to optimize the design of the means allowing the deployment of the sealing membranes, in the secondary vein. Indeed, it is essentially envisaged to deploy the membrane connecting rods, which represent a non-negligible mass, impacting the overall mass of the inverter. This mass is all the more impacted as the connecting rods are generally coupled to means allowing their rotation, such as spring systems, which are heavy and complex.

[0008] Furthermore, in the thrust reversal configuration, just as during at least part of the movement of the movable cowl of the reverser between the direct thrust configuration and the thrust reversal configuration, the sealing membrane presses on an upstream end of this cowl. This support generates a force whose axial component is particularly high, and which thus places a strong load on the actuating means of the movable structure of the reverser, such as actuating cylinders provided to ensure the required translation. Statement of the invention

[0009] To at least partially address the aforementioned drawbacks, the invention firstly 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 traversed by a secondary flow, the reverser also comprising 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 inner wall of the reverser cowl reveals upstream an opening for passage of the secondary flow towards a flow deflection member, the reverser also comprising a membrane for closing the secondary flow, a first end of which is connected to the fixed structure of the reverser, this membrane being arranged at least in part between the flow deflection member and the radially inner wall of the reverser cowl when the mobile structure occupies its advanced direct thrust position, the radially inner wall comprising an upstream end against which the closing membrane bears when the mobile structure occupies its retracted thrust reversal position, exerting on this upstream end a first force with a first axial component oriented downstream.

[0010] According to the invention, the thrust reverser further comprises:

[0011] - a membrane deployment member attached to a second end of the sealing membrane, this deployment member being for example a cable or a strap, or any other flexible force transmission element of elongated / wirelike shape, such as a chain;

[0012] - a fixing or guiding element for the membrane deployment member, the fixing or guiding element being integral with the mobile structure of the inverter

[0013] - a return member of the membrane deployment member, secured to the wall radially internal delimitation of the secondary vein, this member being configured to return the membrane deployment member from the second membrane end, towards the fixing or guiding element,

[0014] the reverser being configured so that when the mobile structure occupies its retracted thrust reversal position, the membrane deployment member exerts, on the fixing or guiding element, a second force with a second axial component oriented upstream.

[0015] The invention provides a simple, reliable and efficient solution, in which the deployment of the shutter membrane is ensured by the movement of the mobile structure of the reverser. The deployment rods and their spring biasing systems are no longer required, which results in a significant reduction in the overall mass of the reverser. The invention is therefore the result of technological research aimed at significantly improving aircraft performance and, in this sense, contributes to reducing the environmental impact of aircraft (decarbonization).

[0016] Furthermore, the invention allows a certain balancing of the axial forces on the mobile structure of the reverser, since the membrane and the membrane deployment member exert on this structure forces whose axial components are in opposite directions. The actuating means of this mobile structure are advantageously less stressed, implying greater stability of this structure, as well as a possible reduction in the dimensioning of its actuating means. In the latter case, the overall mass of the reverser is further reduced, which contributes to a greater reduction in the environmental impact of aircraft.

[0017] The invention preferably provides at least one of the following optional technical features, taken alone or in combination.

[0018] Preferably, the first membrane end is connected to a rear support frame of the flow deflection member, even if any other location can be envisaged within the fixed structure of the inverter, without departing from the scope of the invention.

[0019] Preferably, the fixing or guiding element is fixed to the radially internal wall of the movable cover, preferably being arranged axially downstream of the flow deflection member when the movable structure occupies its forward direct thrust position.

[0020] Preferably, the reverser is designed so that during all or part of the movement of the mobile structure between its forward direct thrust position and its retracted thrust reversal position, during which the membrane is supported on the upstream end by exerting on it a first force with a first axial component oriented downstream, the membrane deployment member exerts on the fixing or guiding element a second force with a second axial component oriented upstream.

[0021] The balancing of forces described above applies in this case, advantageously, during all or part of the rearward movement of the mobile structure.

[0022] According to a preferred embodiment of the invention, the fixing or guiding element of the membrane deployment member is an element for fixing this member to the mobile structure, and preferably to the radially internal wall of the mobile cover.

[0023] According to another preferred embodiment of the invention, the fixing or guiding element of the membrane deployment member is a guiding element of this member, this membrane deployment member comprising a first end connected to the second end of the membrane, as well as a second end opposite the first, preferably connected to the fixed structure of the inverter.

[0024] Here, it is preferably arranged that the membrane deployment member forms a loop with a fixed point, with its first and second ends connected to each other, or connected to the same element of the fixed structure of the inverter, preferably the rear support frame of the flow deflection member.

[0025] Preferably, the membrane deployment member has a cross-section in the form of an aerodynamic profile, and / or the return member has a general shape of revolution with a concave generatrix, particularly adapted to cooperate with the aerodynamic profile shape of the membrane deployment member. An identical or similar shape may be provided for the fixing or guiding element, when it is implemented to constitute a guiding element.

[0026] Preferably, the reverser comprises a sealing device configured so as to provide, at least in the advanced direct thrust position of the mobile structure, a sealing barrier between a first portion of the membrane deployment member located on a first side of the guide element and at least partly in the secondary vein, and a second portion of the membrane deployment member located on another side of the guide element and at least partly in the housing of the reverser cover.

[0027] 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.

[0028] As indicated previously, the reverser preferably comprises a sealing device configured so as to provide, at least in the forward direct thrust position of the mobile structure, a sealing barrier as defined above. Thanks to this sealing device, the air of the secondary flow does not penetrate, or only very little, into the housing of the mobile cover of the reverser. In the direct thrust configuration, this prevents the mobile cover from being subjected to parasitic pressure forces originating from the air of the secondary flow entering the housing of this cover. The actuating means of this mobile structure are advantageously less stressed, implying greater stability of this structure, as well as a possible reduction in the dimensioning of its actuating means.In the latter case, the overall mass of the inverter is further reduced, which contributes to a greater reduction in the environmental impact of aircraft.

[0029] Preferably, the sealing device comprises a chamber for housing the guide element, the chamber having a first opening for the passage of the first portion of the membrane deployment member, and a second opening for the passage of the second portion of the membrane deployment member.

[0030] The second portion of the membrane deployment member is preferably equipped with a closure member, designed to close the second opening when the mobile structure occupies its forward direct thrust position, and to release this opening when the mobile structure moves towards its retracted thrust reversal position. The sealing barrier is then formed by the association of the closure member, such as a simple plug, and the chamber wall.

[0031] According to an alternative, the second opening of the chamber is equipped with a sealing sheath, crossed by the second portion of the membrane deployment member.

[0032] Here, the sealing barrier is formed by the association of the sheath with the deployment member which passes through it. A weak adjustment is preferably retained, while limiting the friction, so as to provide the desired sealing. As in the other embodiments, even if the means employed form a sealing device, a small air leak towards the housing of the movable cover remains tolerated, since such a leak generates only few parasitic forces on this cover.

[0033] Preferably, the inverter comprises an additional guide element also integral with the mobile structure, and arranged so that between the guide element and this additional guide element, the membrane deployment member travels parallel to a longitudinal axis of the sealing sheath, preferably of straight shape. This advantageously allows the sheath to remain straight during the movement of the mobile cover, and therefore to limit its wear in operation.

[0034] According to another preferred embodiment, the first and second portions of the membrane deployment member are formed respectively by first and second sections of the membrane deployment member, separated from each other, and the sealing device comprises:

[0035] - a shaft comprising a first winder on which the first portion is wound of the membrane deployment member, in a first winding direction, as well as a second winder spaced from the first winder along the shaft, and on which the second portion of the membrane deployment member is wound in a second winding direction opposite to the first direction;

[0036] - a chamber for housing the guide element, the chamber having a first opening for the passage of the first portion of the membrane deployment member, and at least one second opening forming a sealing passage for the aforementioned shaft.

[0037] The shaft mounting is preferably a sliding mounting, adapted to form the required sealing barrier against the air of the secondary flow. Here again, a low air leakage remains tolerated.

[0038] Preferably, the inverter comprises a threaded member cooperating with a threaded portion of the shaft, so that the shaft translates along its axis, during its rotation causing the winding / unwinding of the first and second portions of the membrane deployment member. This additional translational movement of the shaft advantageously makes it possible to ensure that the portions of the deployment member do not wind on themselves, which would result in uncontrolled speed variations on the portions of the membrane deployment member.

[0039] Preferably, the first winder comprises a first helical groove for winding the first portion of the membrane deployment member, and the second winder comprises a second helical groove for winding the second portion of the membrane deployment member. Preferably, these two grooves could form a single continuous groove, also serving for cooperation with the aforementioned threaded member, for simplification of production and better guidance of the portions of the membrane deployment member.

[0040] Preferably, each of the first and second winders is generally cylindrical or conical in shape. In both cases, the diameters of the two winders may differ, in order to vary the winding / unwinding speeds of the portions of the membrane deployment member, depending on the needs encountered.

[0041] Other advantages and characteristics of the invention will appear in the detailed non-limiting description below. Brief description of the drawings

[0042] The following detailed description refers to the attached drawings in which:

[0043] [Fig-1] is a schematic half-view in longitudinal section of an assembly propulsion, comprising a thrust reverser shown in direct thrust configuration;

[0044] [Fig.2] is a schematic half-view in longitudinal section of the inverter equipping the propulsion assembly shown in [Fig.l], according to a preferred embodiment of the invention and with the reverser shown in direct thrust configuration;

[0045] [Fig.2A] is a schematic half-view of the reverser shown in [Fig.2], shown during its movement between its direct thrust configuration, and its reverse thrust configuration;

[0046] [Fig.3] is a schematic half-view of the inverter shown in [Fig.2], represented in reverse thrust configuration;

[0047] [Fig.4] is a perspective view of the inverter shown in Figures 2 and 3, re presented in direct push configuration;

[0048] [Fig.5] is a perspective view of the inverter shown in [Fig.4], shown in reverse thrust configuration;

[0049] [Fig.6] is a schematic half-view similar to that of the previous figure, showing the balancing of forces on the mobile cover of the inverter;

[0050] [Fig.7] is a schematic half-view in longitudinal section of the inverter equipping the propulsion assembly shown in [Fig.l], according to another preferred embodiment of the invention and with the reverser shown in direct thrust configuration;

[0051] [Fig.7A] is a schematic half-view of the reverser shown in [Fig.7], shown during its movement between its direct thrust configuration, and its reverse thrust configuration;

[0052] [Fig.8] is a schematic half-view of the inverter shown in [Fig.7], represented in reverse thrust configuration;

[0053] [Fig.9] is a schematic half-view of a part of the inverter, showing speci ficatively the arrangement at the guide member of the membrane deployment cable, according to a preferred embodiment of the invention, in the direct push configuration;

[0054] [Fig. 10] is a schematic half-view similar to that of [Fig.9], in confi thrust reversal configuration;

[0055] [Fig. 11] is a schematic half-view similar to that of [Fig.9], according to an al alternative;

[0056] [Fig. 12] is a schematic half-view similar to that of [Fig.9], according to another alternative ;

[0057] [Fig. 13] is a schematic half-view similar to that of [Fig.9], according to another preferred embodiment of the invention, and still in the pushing configuration direct;

[0058] [Fig.14] is a schematic half-view similar to that of [Fig.13], in reverse thrust configuration;

[0059] [Fig. 15] is a schematic half-view similar to that of [Fig. 13], according to an alternative;

[0060] [Fig. 16] is a schematic half-view similar to that of [Fig. 13], according to another alternative;

[0061] [Fig. 17] is a schematic half perspective view of a preferred embodiment for the membrane deployment cable; and

[0062] [Fig. 18] is a schematic half-view in perspective of the cooperation between the cable shown in the previous figure, and the cable return member. Detailed description of embodiments

[0063] [Fig.l] shows an aircraft propulsion unit 1, having a longitudinal central axis A1.

[0064] Subsequently, the terms “upstream” and “downstream” are defined relative to a general direction SI of flow of the gases through the propulsion unit 1, along the axis A1 when the latter generates thrust. These terms “upstream” and “downstream” could respectively be substituted by the terms “front” and “rear”, with the same meaning.

[0065] The propulsion unit 1 comprises a turbomachine 2, a nacelle 3 as well as a mast (not shown), intended to connect the propulsion unit 1 to a wing (not shown) of the aircraft.

[0066] The turbomachine 2 is in this example a double-flow, double-spool 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.

[0067] 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.

[0068] 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 inwards 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 the radially internal delimiting wall 18 of the secondary vein 21B.

[0069] Radially outwardly, the secondary vein 21B is delimited by the fan casing 11, and, in the configuration of [Fig.l], 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.

[0070] 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.

[0071] The fixed structure also comprises a plurality of deflection grids 32 arranged adjacent to each other around the axis A1, in a circumferential direction 27 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 carried out using a flexible structure, of the membrane / textile type.

[0072] 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 Anglo-Saxon 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 Anglo-Saxon name “C-Duct”, or even a so-called “O-shaped” architecture, known by the Anglo-Saxon name “O-Duct”.

[0073] 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.

[0074] [Fig. 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.

[0075] 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.l], 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 cowls 29 of the reverser. This wall 52, forming the external wall of the secondary vein, is also called an acoustic internal panel.

[0076] This direct thrust configuration is also shown in Figures 2 and 4, while the retracted thrust reversal position of the mobile structure 29 is shown in Figures 3 and 5. [Fig.2A] represents the reverser in an intermediate configuration, during its transit towards the thrust reversal position.

[0077] In [Fig. 3], it is shown that the internal acoustic panel 52 set back from the reverser cowls reveals upstream a passage opening 56 of the secondary flow path 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 retracted thrust reversal position. In other words, the deflection edge 46B gradually moves away from the axis A1 going from the front to the rear, to guide / deflect the air towards the grilles 32 in the thrust reversal configuration.

[0078] In order to divert at least a portion of the secondary flow 20B towards the opening of passage 56 defined axially between the deflection edge 46B and the upstream end 52a of the radially internal 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 possible 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.

[0079] 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, it is observed that this membrane 58 behaves like a boat sail or a parachute / a flying wing when it is put under pressure.

[0080] The sealing membrane 58 comprises a first end 58a, or rear end, connected to the rear end 60a of 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 in a manner specific to the invention which will be described later.

[0081] 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 length of the membrane, only the front end 58b of the membrane being sandwiched between the upstream end 52a of the wall 52, and the deflection edge 46B.

[0082] Also, as can be seen in [Fig. 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. Thus, the membrane 58 presses on the upstream end 52a of the radially internal wall, here during the entire movement of the mobile structure to its rearward thrust reversal position.

[0083] The part of the membrane 58 which is located radially outwards relative to its bearing 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.

[0084] In this preferred embodiment, the radially internal attachment of the membrane 58 is carried out using one or more deployment members 62, distributed circumferentially in relation to the axis A1 of the inverter. These deployment elements 62, arranged partly in the secondary vein 21B, take the form of cables or straps, or any other force transmission element of a flexible nature and of elongate shape. In the preferred case of cables, these may be elastic, for example using Kevlar cables, and these same cables may be put under tension when the sliding cover 33 is closed.

[0085] As mentioned previously, the cables 62 are spaced circumferentially from each other within the secondary vein 21 B, and their number can for example vary from two to ten in association with the same membrane.

[0086] Each cable 62 comprises a first end 62a connected to the second membrane end 58b. Its second end 62b, opposite the first, is connected to an element 64 for fixing the cable 62. This element 64 is here a cable fixing element, integral with the mobile structure 29. More precisely, the fixing element 64 is fixed to the radially internal wall 52 of the mobile cover 33, preferably being arranged axially downstream of the grids 32 when the mobile structure occupies its forward direct thrust position. Even more preferably, still in this same position, the fixing element 64 is arranged axially downstream of the rear end 60a of the rear frame 60 for supporting the grids, that is to say at the level of the rear axial bottom of the housing 54.

[0087] Thanks to this design, the deployment of the membrane 58 is advantageously carried out by the traction of the movable cowl 33, during its transit towards its rearward thrust reversal position. This simple, reliable and low-cost operation impacting in terms of mass is made possible by the installation of a member 66 for returning the cable 62. This return member 66, such as a pulley, is integral with the radially internal delimiting wall 18 of the secondary vein 21 B, projecting into this vein, or preferably being at least partially masked in order to limit aerodynamic disturbances, in the direct thrust configuration.

[0088] The return member 66 is configured to return the cable 62 coming from the second membrane end 58b, towards the fixing element 64. Due to this return, the cable 62 extends in a general V shape between its two ends 62a, 62b, being open radially towards the outside.

[0089] Furthermore, with reference to [Fig. 6], the membrane 58 exerts on the upstream end 52a of the wall 52 a first force 70a, with a first axial component 72a oriented downstream. Simultaneously, the cable 62 exerts on the fixing element 64, and therefore on the same wall 52 of the movable cover 33, a second force 70b with a second axial component 72b oriented upstream.

[0090] The invention advantageously allows a certain balancing of the axial forces on the mobile structure of the inverter, since the membrane 58 and the cable 62 exert on the mobile cover 33 forces whose axial components 72a, 72b are in opposite directions.

[0091] This balancing, resulting from the aforementioned opposing forces 72a, 72b, preferably takes place throughout the movement of the mobile structure 31, between its forward direct thrust position and its rearward thrust reversal position.

[0092] It is noted that in this preferred embodiment, the fixing element 64 could be fixed to another part of the mobile structure 31, without departing from the scope of the invention.

[0093] Another preferred embodiment of the invention is shown in Figures 7, 7A and 8. Here, the element 64 is no longer a fixing element for the cable 64, but a guiding element for the latter, such as a pulley. Also, after passing through the guiding element 64, bearing on it while passing downstream of this same guiding element 64, the cable 62 goes back forward through the housing 54, to its second end 62b fixed on the rear end 60a of the grid support 60. With this design, the cable 62 thus forms a loop with a fixed point, located on the rear grid support frame 60 on which its two ends 62a, 62b are fixed. The cable loop could alternatively not be complete, but still be closed by an element of the fixed structure 31 of the inverter, on which the two cable ends 62a, 62b would remain fixed, without departing from the scope of the invention.This element of the fixed structure 31 could be the rear grid support frame 60.

[0094] In this other preferred embodiment of the invention, the two ends of cables 62a, 62b are indeed integral with the fixed structure 31 of the inverter, but the path followed by the loop-shaped cable, and in particular its passage through the guide element 64, still allows the deployment of the membrane 58 by the downstream movement of the mobile structure 29.

[0095] Several preferred embodiments can be envisaged for the design of the inverter at the level of the guide element 64. Indeed, at this location, the cable 62 comes from the secondary vein 21B, passes through the internal wall 52 of the movable cowl 33, then travels upstream within the housing 54. Also, to avoid or limit as much as possible the risks of air leakage from the secondary flow towards this housing 54, in particular in the direct thrust configuration, the inverter comprises a sealing device 80, a first mode of which is shown in FIGS. 9 and 10.

[0096] Generally speaking, this device 80 for airtightness of the secondary flow is configured so as to provide, at least in the advanced position of direct thrust of the mobile structure, a sealing barrier between a first portion of cable 162a located on a first side of the guide element 64, here the side of the vein 20B, and a second portion of cable 162b located on another side of the guide element 64, here the side of the housing 54 of the reverser cover 33.

[0097] Thanks to this sealing device 80, the air of the secondary flow does not penetrate, or only very little, into the housing 54, thus avoiding pressure stresses, towards the rear, of the movable cover 33.

[0098] In this preferred embodiment of the invention, the sealing device 80 comprises a fitting attached to the housing 54, inside the latter, being fixed to the radially external surface of the internal wall 52. This fitting forms a chamber 82 inside which the guide element 64 is housed. The sealed chamber 82 nevertheless has two openings, namely a first opening 82a for the passage of the first portion of cable 162a coming from the vein 21 B, and a second opening 82b for the passage of the second portion of cable 162b. Here, this second portion of cable 162b is equipped with a closing member 84, such as a plug, designed to close the second opening 82b when the mobile structure occupies its forward direct thrust position. The desired sealing barrier is then formed by the association of the plug 84 with the chamber wall pierced with the second opening 82b.During the transit of the movable cowl 33, towards its retracted thrust reversal position, the concomitant movement of the second portion of cable 162b causes this plug 84 to release the second opening 82b, thus breaking the sealing barrier.

[0099] According to an alternative shown in Figures 11 and 12, the second opening 82b is equipped with a sealing sheath 86, crossed by the second portion of cable 162b. The sealing barrier is then formed by the association of the sheath 86 with the second portion of cable 162b which crosses it.

[0100] A slight adjustment is made between these two elements 162b, 86 so as to provide the desired level of sealing, while limiting friction. The sheath 86, preferably flexible, forms a design tolerating a small air leakage towards the housing 54, without this being detrimental to the cover 52.

[0101] As shown in [Fig. 12], an additional guide element 64' can be installed upstream of the sealing sheath 86. It can be fixed to the fitting forming the chamber 82, just like the guide element 64. The arrangement is made in such a way that between the guide element 64 and the additional guide element 64', the second cable portion 162b runs parallel to a longitudinal axis of the sealing sheath, of straight shape. This allows the sheath 86 to remain straight during the movement of the movable cover, always in the same orientation, and therefore to limit the wear of this sheath, as well as the leakage that may result therefrom.

[0102] Another preferred embodiment is shown in Figures 13 and 14. In this embodiment, the cable is not single and continuous, but is formed by two cable sections separated from each other, at the level of the guide element 64. Indeed, the first and second cable portions 162a, 162b are here respectively formed by first and second sections of the membrane deployment member, separate and independent of each other.

[0103] In addition, the sealing device 80 comprises a shaft, forming the guide element 64. This shaft has the particularity of comprising several portions, one of which constitutes a first winder 164a on which the first portion of cable 62a is wound, in a first winding direction. Another portion of this shaft constitutes a second concentric winder 164b, spaced from the first winder along the shaft, and on which the second portion of cable 62b is wound, in a second winding direction opposite to the first direction.

[0104] The sealing device 80 also comprises the chamber 82 for housing the guide element 64, formed by the aforementioned shaft. Just as in the previous embodiment, the chamber 82 has the first opening 82a for the passage of the first portion of cable 162a, and the second opening 82b forming a sealing passage for the shaft 64. More precisely, the passage is preferably made between the two concentric portions of the shaft, respectively forming the two winders 164a, 164b. This assembly is preferably a sliding assembly, suitable for the formation of the required sealing barrier, with respect to the air of the secondary flow. Here too, a small air leak remains tolerated.

[0105] During transit towards the thrust reversal configuration, the first cable portion 162a winds around the first reel 164a, while concomitantly, the second cable portion 162b unwinds from the second reel 164b. the opposite phenomenon occurs when the mobile structure 29 re-enters.

[0106] The cable portions 162a, 162b can be wound on themselves at the level of the winders 164a, 164b, but the design is preferably retained so that each of these portions 162a, 162b is wound along its associated winder, and not on itself. In other words, the turns formed by these cable portions 162a, 162b follow one another only axially along the shaft, which makes it possible to obtain constant winding / unwinding speeds. To do this, a threaded member such as a nut 90 is provided cooperating with a threaded portion 92 of the shaft, so that the shaft also translates along its axis, during its rotation causing the winding / unwinding of the cable portions 162a, 162b. The nut 90 can be fixedly carried by the fitting forming the chamber 82, as shown in Figures 13 and 14.

[0107] It is noted that another second opening 82b is provided on the wall opposite the chamber 82, so as to guide the shaft at two points of this chamber forming a support. This second guide, also forming a sealing passage, can be replaced or provided in addition to a sealed guide produced by the nut 90 and the threaded portion 92 of the shaft.

[0108] As indicated previously, the additional translational movement of the shaft 64 advantageously makes it possible to ensure that the cable portions 162a, 162b do not wind on themselves, which would result in uncontrolled speed variations on these portions 162a, 162b.

[0109] In the alternative shown in [Fig. 15], the first winder 164a comprises a first helical groove 94a for winding the first portion of cable 162a, just as the second winder 164b comprises a second helical groove 94b for winding the second portion of cable 162b. This design facilitates the winding of cables in turns which follow one another axially. Preferably, and for greater simplicity of production, the two grooves 94a, 94b form a single continuous groove, also serving for cooperation with the nut 90. The whole thus remains comparable to a single thread, of constant pitch, performing three functions simultaneously. Here, the nut 90 can be arranged between the two winders 164a, 164b.

[0110] Moreover, it is noted that it is therefore the nut 90 which can be housed in one of the second openings 82b of the chamber, always forming a sealing passage within this sealing device 80. In addition, the cooperation between the two threads, at the level of the nut 90, also reduces air leaks outside the chamber. Thus, the thread of the nut could even be assimilated to the sealing passage through the chamber 82, within the meaning of the present invention. [YES] In the embodiments described above, the two winders 164a, 164b are both two of generally cylindrical shape, and of identical diameter. However, these two diameters could differ, in order to differentiate in a controlled manner the winding / unwinding speeds of the cable portions 162a, 162b.

[0112] According to another alternative shown in [Fig. 16], one or both of the reels could have a generally conical shape, to vary in a controlled manner the winding / unwinding speeds of one or both of the cable portions 162a, 162b, during transit.

[0113] Finally, Figures 17 and 18 show that the cable 62 is not necessarily of circular section. It may have a section in the form of an aerodynamic profile, with for example a reinforced core 96 of circular section at the leading edge. In order to facilitate its passage through the return member 66, and also through the element 64 when it forms a cable guide element, each of these members may have a general shape of revolution with a concave generator. As shown in [Fig. 18], the cable 62 can thus be wound naturally around this hollowed member 66, with its incoming and outgoing portions which are offset from each other so as not to be located in the same plane.

[0114] 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

1. Claims 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 traversed by a secondary flow (20B), the reverser also comprising a movable structure (29) comprising at least one reverser cowl (33) having a housing (54) open upstream and delimited between a radially external wall (50) and a radially internal wall (52) of the reverser cowl (33), the movable structure being movable in translation relative to the fixed structure along a longitudinal central axis (A1) of the reverser, between an advanced direct thrust position and a retracted thrust reversal position in which the retracted radially internal wall (52) of the reverser cowl reveals upstream a passage opening (56) of the secondary vein (21B) towards a member of flow diversion (32),the reverser also comprising a membrane (58) for closing the secondary flow path (21B), a first end of which is connected to the fixed structure of the reverser, this membrane being arranged at least in part between the flow deflection member (32) and the radially internal wall (52) of the reverser cowl (33) when the mobile structure occupies its forward direct thrust position, the radially internal wall (52) comprising an upstream end (52a) against which the closing membrane (58) bears when the mobile structure occupies its retracted thrust reversal position, exerting on this upstream end (52a) a first force (70a) with a first axial component (72a) oriented downstream, characterized in that it further comprises:, - a membrane deployment member (62) attached to a second end (58b) of the sealing membrane (58); - an element (64) for fixing or guiding the membrane deployment member (62), the fixing or guiding element (64) being integral with the mobile structure (29) of the inverter; - a member (66) for returning the membrane deployment member, secured to the radially internal delimiting wall (18) of the secondary vein (21B), this member being configured to return the membrane deployment member (62) from the second membrane end (58b), in the direction of the fixing or guiding element (64); the reverser being configured so that when the mobile structure (29) occupies its retracted thrust reversal position, the membrane deployment member (62) exerts, on the fixing or guiding element (64), a second force (70b) with a second axial component (72b) oriented upstream.

2. Inverter according to claim 1, characterized in that the membrane deployment member (62) is a cable or a strap.

3. Inverter according to claim 1 or 2, characterized in that the first membrane end (58a) is connected to a rear frame (60) supporting the flow deflection member (32).

4. Inverter according to any one of the preceding claims, characterized in that the fixing or guiding element (64) is fixed to the radially internal wall (52) of the movable cover, preferably being arranged axially downstream of the flow deflection member (32) when the movable structure (29) occupies its advanced direct thrust position.

5. Reversing device according to any one of the preceding claims, characterized in that it is designed so that during all or part of the movement of the mobile structure (29) between its forward direct thrust position and its retracted thrust reversal position, during which the membrane (58) is supported on the upstream end (52a) by exerting on it the first force (70a) with the first axial component (72a) oriented downstream, the membrane deployment member (62) exerts on the fixing or guiding element (64) the second force (70b) with the second axial component (72b) oriented upstream.

6. Inverter according to any one of the preceding claims, characterized in that the element (64) for fixing or guiding the membrane deployment member is an element for fixing this member (62) to the mobile structure (29), and preferably to the radially internal wall (52) of the mobile cover.

7. Inverter according to any one of claims 1 to 5, characterized in that the element (64) for fixing or guiding the membrane deployment member is a guide element for this member (62), this membrane deployment member (62) comprising a first end (62a) connected to the second membrane end (58b), as well as a second end (62b) opposite the first, preferably connected to the fixed structure (31) of the inverter.

8. Inverter according to claim 7, characterized in that the de- membrane folding (62) forms a loop with a fixed point, with its first and second ends (62a, 62b) connected to each other, or connected to the same element (60) of the fixed structure (31) of the inverter, preferably a rear frame (60) supporting the flow deflection member (32).

9. Inverter according to claim 7 or 8, characterized in that the inverter comprises a sealing device (80) configured so as to provide, at least in the advanced direct thrust position of the mobile structure (29), a sealing barrier between a first portion (162a) of the membrane deployment member (62) located on a first side of the guide element (64) and at least partly in the secondary vein (21b), and a second portion (162b) of the membrane deployment member (62) located on another side of the guide element (64) and at least partly in the housing (54) of the inverter cover.

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 the preceding claims.

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