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

Abstract

The invention relates to a thrust reversal system for an aircraft turbojet (2), the thrust reversal system (18) delimiting a secondary vein (16a), comprising an internal fixed structure (160) and an external fixed structure (162) connected to each other at at least one bifurcation (164, 166) delimited on either side by a wall (16a, 160b) of the internal fixed structure (160), the system comprising: at least one movable cowl (20), movable between a retracted position and a deployed position; a set of air deflection devices; at least one closure membrane (24), movable between a retracted position and a deployed position; the sealing membrane (24) being attached to at least one attachment element fixed relative to the external fixed structure (162) and, at front attachment points (240), to deployment devices (26, 28);the deployment devices (26, 28) comprising, for the or for each sealing membrane at least a first and a second traction cable (28), each traction cable (28) being connected to the sealing membrane and to a pulling system (30), the pulling system (30) making it possible to pull on the traction cables during deployment of the thrust reverser device. Figure 5.;

Description

Title of the invention: Thrust reversal system for aircraft turbojet, nacelle and propulsion assembly comprising such a system Technical field

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

[0002] Thrust reversers are systems 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 generally comprise deflection grids integrated into a fixed structure of the reverser, intended to be connected to a turbomachine casing. A 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 reverser position. In the forward direct thrust position, the deflection grids are arranged in a cavity of the mobile reverser cowls, and they are isolated from the secondary flow path of the propulsion unit by a radially internal wall of the reverser cowls. On the other hand, in the rearward thrust reverser position, the rearward radially internal wall of the reverser cowls defines an opening for the secondary flow path to the deflection grids.

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

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

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

[0007] With this in mind, solutions have been developed for closing the secondary vein using one or more deployable membranes. Such a membrane design is for example known from document FR 3 076 864 A1.

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

[0009] When the mobile structure moves towards its rearward thrust reversal position, the membrane gradually deploys in the vein by plunging radially towards the inside of the latter, driven by the connecting rod(s) which tilt downstream and also radially towards the inside.

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

[0011] The solution for deploying and removing the sealing membrane using connecting rods is satisfactory, but it nevertheless remains improvable. Indeed, in the thrust reversal configuration, the position of the inclined connecting rods in the secondary vein is not known with great precision, nor that of the membrane end connected to these connecting rods, in particular with regard to the connecting rods located in the immediate vicinity of the bifurcations. Thus, the distance between the sealing membrane and the internal fixed structure of the nacelle is not always maintained at a value ensuring optimized operation of the thrust reversal system, since the leakage level generated by the membrane is not optimized.

[0012] The objective of the present invention is to propose a thrust reversal system comprising a sealing membrane making it possible to finely manage the position of the membrane in the vein, and therefore to precisely adjust the level of leakage generated by the membrane when it is deployed in the secondary vein. Statement of the invention

[0013] For this purpose, the invention provides a thrust reversal system for a turbo nacelle aircraft reactor, the thrust reversal system delimiting a secondary vein for the passage of a secondary flow of the turbojet, the thrust reversal system comprising an internal fixed structure and an external fixed structure connected to each other at the level of at least one bifurcation, the bifurcation being delimited on either side by a bifurcation wall formed by the internal fixed structure, the thrust reversal system comprising:

[0014] - at least one movable hood, movable between a retracted position, in which the thrust reverser system is in a direct jet configuration, and a deployed position, in which the thrust reverser system is in a reverse jet configuration;

[0015] - a set of air deflection devices;

[0016] - at least one sealing membrane, movable between a retracted position cor corresponding to the retracted position of the movable hood, in which it is at least partially housed in an internal space of the movable hood, and a deployed position corresponding to the deployed position of the movable hood, in which it is at least partially deployed in the secondary vein, so as to divert a majority portion of the secondary flow towards the air diversion devices;

[0017] the sealing membrane being fixed, at rear fixing points, to at least one fixing element fixed relative to the external fixed structure and, at front fixing points, to deployment devices;

[0018] the deployment devices comprising, for the or each sealing membrane, at least a first traction cable and a second traction cable, the first and second traction cables each having a first end connected to the front attachment point of the sealing membrane closest to the corresponding bifurcation wall, and a second end located outside the secondary vein and connected to a pulling system, each traction cable penetrating into the secondary vein via a respective orifice provided in the internal fixed structure, the pulling system making it possible to pull on the second end of the corresponding traction cable during deployment of the thrust reverser device, so as to reduce the distance between the first end of the traction cable and the corresponding passage orifice.

[0019] Thus, by providing a traction cable near the or each bifurcation, it is possible, at the level of each cable, to precisely fix the distance between the sealing membrane and the internal fixed structure of the nacelle when the inversion system is deployed. Thus, the position of the end of the membrane is precisely fixed, which in particular makes it possible to finally adjust the level of leakage generated by the membrane during the thrust inversion phases.

[0020] The thrust reversal system according to the invention may comprise one or more of: several of the following optional features, considered alone or in all possible combinations.

[0021] According to one characteristic, the pulling system comprises a support for fixing the second end of the pulling cable, the fixing support being fixed relative to the movable cover.

[0022] According to one characteristic, the traction cable is connected to the pulling system by a device of variable length, for example an elastic return device.

[0023] According to one characteristic, the pulling system comprises a return device secured to the movable cowl, the second end of the traction cable being secured to a fixing support fixed relative to the external fixed structure of the thrust reversal system, the return device comprising for example a pulley.

[0024] According to one characteristic, the pulling system comprises a spring, such as a gas spring, or a pneumatic cylinder.

[0025] According to one characteristic, the thrust reversal system comprises a guidance system configured to impose the routing of the traction cable outside the secondary vein.

[0026] According to one characteristic, the guidance system comprises at least one return system, comprising for example one or more pulleys.

[0027] According to one characteristic, the guidance system comprises a sheath in which a part of the traction cable is inserted.

[0028] According to one characteristic, the deployment devices comprise passive deployment devices, of fixed length, a first end of which is secured to the internal fixed structure, and a second opposite end of which is secured to a front fixing point of the sealing membrane, the passive deployment devices being for example connecting rods or cables.

[0029] According to one characteristic, the thrust reversal system comprises at least one additional traction cable, the additional traction cable being associated with one of the passive deployment devices which are not associated with the first and second traction cables.

[0030] The invention also relates to a nacelle comprising a thrust reversal system in accordance with that defined above.

[0031] The invention also relates to a propulsion unit comprising a dual-flow turbojet and a nacelle conforming to that defined above, as well as an aircraft comprising at least one such propulsion unit. Brief description of the drawings

[0032] [Fig-1] [Fig. 1] is a perspective view of an aircraft propulsion unit, comprising a dual-flow turbojet engine and a nacelle carrying a system grid thrust reverser, the thrust reverser system being shown in a retracted configuration.

[0033] [Fig.2] [Fig.2] represents the propulsion assembly of [Fig.l], the thrust reverser system being represented in a deployed configuration.

[0034] [Fig.3] [Fig.3] is a partial view of a propulsion assembly conforming to that of [Fig.l], the nacelle carrying a reversing system with deflector membranes, the thrust reversing system being in a deployed configuration.

[0035] [Fig.4] [Fig.4] is a partial view of the rear section of the nacelle of [Fig.l], with the thrust reverser system in a retracted configuration.

[0036] [Fig.5] [Fig.5] is a view similar to [Fig.4], with the thrust reverser system in a deployed configuration.

[0037] [Fig.6] [Fig.6] is a schematic sectional view of a portion of the nacelle of [Fig.3], with the thrust reverser system in a retracted position.

[0038] [Fig.7] [Fig.7] is a view similar to [Fig.6], the thrust reversal system being shown during deployment, in a first intermediate position.

[0039] [Fig.8] [Fig.8] is a view similar to [Fig.6], the thrust reversal system being shown during deployment, in a second intermediate position.

[0040] [Fig.9] [Fig.9] is a view similar to [Fig.6], the thrust reverser system being shown in the deployed position.

[0041] [Fig. 10] [Fig. 10] is a schematic sectional view similar to [Fig.6], showing an alternative method of fixing the first end of the traction cable.

[0042] [Fig. 11] [Fig. 11] is a schematic sectional view similar to [Fig. 6], showing an alternative method of attaching the second end of the traction cable, with the thrust reverser system in the retracted position.

[0043] [Fig. 12] [Fig. 12] is a schematic sectional view similar to [Fig. 11], with the thrust reverser system in the deployed position.

[0044] [Fig. 13] [Fig. 13] is a schematic sectional view similar to [Fig. 6], showing a traction cable guidance system comprising fixed pulleys, the thrust reverser system being in the retracted position.

[0045] [Fig. 14] [Fig. 14] is a schematic sectional view similar to [Fig. 13], with the thrust reverser system in the deployed position.

[0046] [Fig. 15] [Fig. 15] is a schematic sectional view similar to [Fig. 6], showing a traction cable guidance system comprising at least one movable pulley, the thrust reversal system being in the retracted position.

[0047] [Fig. 16] [Fig. 16] is a schematic sectional view similar to [Fig. 15], with the thrust reverser system in the deployed position.

[0048] [Fig. 17] [Fig. 17] is a schematic sectional view similar to [Fig. 6], showing a traction cable pulling system, the thrust reverser system being in the retracted position.

[0049] [Fig. 18] [Fig. 18] is a schematic sectional view similar to [Fig. 17], with the thrust reverser system in the deployed position.

[0050] [Fig. 19] [Fig. 19] is a schematic sectional view similar to [Fig. 17], showing a variant of the traction cable pulling system, the thrust reverser system being in the retracted position.

[0051] [Fig.20] [Fig.20] is a schematic sectional view similar to [Fig. 19], with the thrust reverser system in the deployed position.

[0052] [Fig.21] [Fig.21] is a view similar to [Fig.5], showing a variant of the thrust reverser system in which additional traction cables are provided. Detailed description

[0053] Figures 1 and 2 show an aircraft propulsion unit 1, having a longitudinal central axis A.

[0054] Subsequently, the terms "upstream" and "downstream" are defined relative to a general direction of flow of gases through the propulsion unit, 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.

[0055] The propulsion unit 1 comprises a turbomachine 2 and a nacelle 3. The propulsion unit 1 is intended to be connected via a mast 4 to a wing (not shown) of an aircraft.

[0056] In this example, the turbomachine 2 is a dual-flow turbojet engine, comprising in particular a gas generator and a fan. The nacelle 3 comprises a front section 10 forming an air inlet 10a, a middle section 12 which comprises two fan cowls 12a surrounding a fan casing of the turbojet engine, and a rear section 16.

[0057] In operation, an air flow enters the propulsion unit 1 through the air inlet 10a, passes through the fan of the turbojet engine and then divides into a primary flow and a secondary flow. The primary flow flows in a primary gas circulation vein passing through the gas generator of the turbojet engine 2. The secondary flow flows in a secondary vein surrounding the gas generator. The secondary vein is delimited radially inwards by an internal structure of the nacelle which envelops the gas generator.

[0058] The rear section 16 of the nacelle carries a thrust reversal system 18. [Fig.l] shows the nacelle 3 in the direct jet configuration, i.e. with the thrust reverser system in the retracted position, while [Fig.2] shows the nacelle 3 in the reverse jet configuration, i.e. with the thrust reverser system in the deployed position. Thus, it can be seen in [Fig.3] that a movable cowl 20 of the rear section 16 is in the retracted position, revealing a set of air deflection devices 22, which are, in the example of FIGS. 1 and 2, air deflection grilles.

[0059] [Fig. 3] is a partial view of the rear section 16 of the nacelle 3 of the propulsion unit 1, in a variant in which the air deflection devices 22 are deflector membranes. As visible in [Fig. 3], which shows the thrust reversal system 18 in the deployed position, all of the deflector membranes 22 are deployed, so as to redirect the secondary air flow outside the nacelle 3, towards the front.

[0060] Figures 4 and 5 represent a half-part of the rear section 16 of the nacelle 3, which comprises the thrust reversal system 18, the latter being respectively in the retracted configuration and in the deployed configuration.

[0061] As visible in [Fig. 4], each half-part of the rear section 16 of the nacelle comprises an internal fixed structure 160 (also called IFS according to the English term "Inner Fixed Structure") and an external fixed structure 162 (also called OFS according to the English term "Outer Fixed Structure"). In the example, the rear section 16 of the nacelle has a so-called "D-shaped" structure (commonly referred to by the English term "D-duct"). In such a configuration, the internal fixed structure and the external fixed structure are connected to each other at the level by means of two connecting islands 164, 166, arranged in the secondary vein 16a, respectively forming a first bifurcation 164 and a second bifurcation 166.For a propulsion unit attached to an aircraft wing, the bifurcations are arranged respectively in the so-called "twelve o'clock" positions (for the first bifurcation 164, or upper bifurcation 164) and "six o'clock" positions (for the second bifurcation 166, or lower bifurcation 166). It is recalled that the "twelve o'clock" and "six o'clock" positions are conventionally defined by analogy with a watch dial, the nacelle being in the operating position, i.e. under the wing. The "twelve o'clock" position is thus located at the nacelle attachment mast, while the "six o'clock" position corresponds to the diametrically opposite position. For a propulsion unit attached to the fuselage of an aircraft, the bifurcations will be arranged in the so-called "three o'clock" and "nine o'clock" positions.Furthermore, although the nacelle described in the present application has a D-shaped structure, the present invention applies to any type of nacelles, and in particular to nacelles having an “O” or “C” structure, structures in . in which only one bifurcation is provided. Each bifurcation 164, 166 is delimited at the level of the secondary vein 16a, on either side, by a bifurcation wall 160a, 160b formed by a part of the fixed internal structure 160 of the rear section 16.

[0062] In the configuration of figures 1 and 4, the secondary vein 16a is, at the level of the rear section 16, delimited by the internal fixed structure 160, and the movable cowls 20, which form a part of the rear section 16 of the nacelle 3. The secondary vein 16a is in direct jet configuration and is optimized to allow the secondary flow to pass towards the rear of the propulsion unit, opposing it with the lowest possible resistance.

[0063] In the configuration of figures 2, 3 and 5, the movable cowls 20 are in the retracted position and the secondary vein 16a is at least partially obstructed by a device for closing the secondary vein, in the example a closing membrane 24. In its deployed position, the closing membrane 24 makes it possible to block part of the secondary flow to redirect it towards the air deflection devices 22 and therefore towards the outside of the nacelle, thus generating the desired counter-thrust.

[0064] Figures 6 to 9 show a section of the rear section 16 of the nacelle 3, when it is equipped with deflector membranes 22 such as those shown in [Fig.3].

[0065] [Fig.6] shows the thrust reverser system 18 in the retracted configuration, i.e. the nacelle 3 is in the direct jet configuration.

[0066] The thrust reversal system 18 comprises at least one movable cowl 20, in the example two movable cowls 20, which form the outer surface of the rear section 16 of the nacelle. The thrust reversal system 18 further comprises the air deflection devices 22 and the devices 24 for closing the secondary vein 16a. The thrust reversal system 18 comprises actuators (not shown), in particular electromechanical actuators, making it possible to slide the movable cowl between a retracted position ([Fig. 6]) and a deployed position ([Fig. 9]), and vice versa. This transition is effected by a translational movement along the longitudinal axis of the nacelle, corresponding to the longitudinal axis A of the propulsion unit 1.

[0067] When the thrust reversal system is in the retracted position ([Fig.6]), the movable cowl 20 is in the retracted position, corresponding to an advanced position in which it ensures aerodynamic continuity with the middle section of the nacelle, and the sealing membrane 24 is in the retracted position, a position in which it is at least partly housed in an internal space 200 of the corresponding movable cowl 20, located between an internal surface 202 and an external surface 204 of the movable cowl 20.

[0068] When the thrust reversal system is in the deployed position ([Fig.9]), the movable cowl 20 is in the deployed position, corresponding to a retracted position, in which it uncovers the deflection devices 22, in the example of the deflector membranes ; the sealing membranes 24 are in the deployed position, in which position they at least partially obstruct the secondary vein 16a.

[0069] In this configuration, the action of the closure membranes 24 and the deflector membranes 22 makes it possible to redirect the secondary flow outside the nacelle, towards the front in order to create a counter-thrust. The passage into the deployed position of the closure membranes 24 is obtained by the combined action of the aerodynamic forces generated by the secondary flow circulating in the secondary vein 16a and of deployment devices 26 attached to the internal fixed structure 160 of the nacelle.

[0070] The sealing membrane 24 is connected to the deployment devices 26, which in the example are connecting rods 26. Each connecting rod 26 is fixed and articulated to the internal fixed structure 160 of the nacelle. In the example, each connecting rod 26 is articulated at a first end 260, the first end 260 being rotatably mounted in a fitting 264 secured to the internal fixed structure 160 of the nacelle 3.

[0071] Each connecting rod 26 is fixed, at a second end 262 opposite the first end 260, to the sealing membrane 24. Thus, as can be seen in Figures 7 and 8, which show intermediate positions of the movable cover 20 between the retracted and deployed positions, during the movement of the latter towards the deployed position visible in [Fig.9], the recoil of the movable cover 20 makes it possible to progressively release the sealing membrane 24, the latter being pushed backwards by the flow of air circulating in the secondary vein (represented by the arrow F), at the same time as the movable cover 20 moves backwards. At the same time as the sealing membrane 24 is pushed rearward, it drives the second end 262 of each connecting rod 26, to which it is attached at front attachment points 240, which causes a rotational movement of each connecting rod 26 rearward.This rotational movement drives the second end 262 of each connecting rod 26 towards the internal fixed structure 160, and therefore the deployment of the sealing membrane 24 in the secondary vein.

[0072] The sealing membrane 24 is furthermore fixed, at the level of rear fixing points 242, to one or more fixing elements 168, which are fixed relative to the external fixed structure 162 of the rear section 16 of the nacelle. These fixing elements 168 are arranged downstream of the deflection devices 22. Thus, as visible in [Fig. 9], when the thrust reversal system is deployed, the sealing membrane 24 is deployed in the secondary vein, being retained, at the level of the first fixing points 240, by the connecting rods 26 and, at an opposite end, at the level of the second fixing points 242, by the fixing elements 168.

[0073] As mentioned above, in the example of Figures 6 to 9, the air deflection devices are deflector membranes 22. As visible in [Fig.3], it is provided, between some or between each of the deflector membranes 22, a longitudinal upright 220. In the example of figures 6 to 9, each fixing element 168 of the sealing membrane 24 is integral with one of these longitudinal uprights 220.

[0074] In the example of Figures 6 to 9, the connecting rods 26 are passive deployment devices 26, because they are driven from their retracted position ([Fig.6]) to their deployed position ([Fig.9]) by the action of the sealing membrane 24. The passive deployment devices 26 have a fixed length. They are connecting rods 26 as in the example of the figures, but the connecting rods 26 can be replaced by other devices, such as cables of fixed length.

[0075] According to the invention, the passive deployment devices 26 which are located in the immediate vicinity of a wall 160a, 160b delimiting the single bifurcation (in the case of an “O” or “C” structure) or one of the first and second bifurcations 164, 166 (in the case of a “D” structure) are assisted by a deployment device comprising a traction cable 28. In the example of the figures, these are the passive deployment devices 26 located in the immediate vicinity of the 12 o'clock and 6 o'clock positions, that is to say the deployment devices which are located closest respectively to the upper bifurcation 164 and the lower bifurcation 166, and therefore to the walls 160a and 160b. At least two traction cables 28 are thus provided per half-part of the rear section 16 of the nacelle, i.e. at least four traction cables 28 for the entire nacelle 3.

[0076] Each traction cable 28 comprises a first end 280 which is secured directly or indirectly to a first fixing point 240 of the sealing membrane 24, being for example either fixed to the sealing membrane 24 or to the corresponding passive deployment device 26. Each traction cable 28 comprises, at an opposite end, a second end 282 which is linked to a pulling system 30. In the example of FIGS. 6 to 9, the pulling system 30 comprises the movable cover 20, the second end 282 of the traction cable 28 being fixed to a fixing support 206 secured to the movable cover 20 and fixed relative to the latter.

[0077] Each traction cable 28 comprises a first portion 280a, which is located in the secondary vein 16a when the thrust reverser system is in the retracted position, and a second portion 280b, which is located inside the internal fixed structure 160 when the thrust reverser system is in the retracted position. As visible in [Fig. 6], each traction cable 28 enters the secondary vein 16a via an orifice 160c formed in the corresponding wall 160a, 160b (or close to this wall). As can be seen in FIGS. 6 to 9, the recoil of the movable cowl 20 during deployment of the thrust reverser system drives the second end 282 of each traction cable rearward, which amounts to pulling the cable through the corresponding orifice 160c, thus gradually reducing the distance between the corresponding orifice 160c and the first end 280 of each traction cable 28. Pulling the cable will therefore make it possible to pull a portion of the shutter membrane 24 towards the corresponding wall 160a, 160b of the fixed internal structure 160. This ensures that the shutter membrane 24 deploys sufficiently at the bifurcations 164, 166 of the rear section 16. Furthermore, the traction cables 28 make it possible to finely adjust the final distance between the shutter membrane 24 and the fixed internal structure at the deployment devices 26 equipped with a traction cable 28. By finely adjusting this distance, it is possible to precisely manage the level of leakage generated by the shutter membrane 24, which is essential both for the proper operation of the turbojet and for the overall effectiveness of the thrust reverser system.

[0078] The traction cables are preferably non-stretchable cables, or very weakly stretchable cables. These are, for example, metal cables or cables made of a polymer material.

[0079] A system for guiding the cable 32 may be provided, over all or part of the path of the traction cable 28 between the orifice in the wall of the internal fixed structure and the second end 282 of the traction cable 28, fixed to the movable cover 20. In the example of FIGS. 6 to 13, the guiding system 32 comprises a sheath 320, for example a rigid, flexible or semi-rigid sheath.

[0080] In a variant shown in [Fig. 10], the traction cables 28 can be attached to a respective passive deployment device 26. In the example of [Fig. 10], each traction cable 28 is attached to the corresponding connecting rod 26, between the first and second ends 260a, 260b thereof.

[0081] In a variant shown in Figures 11 and 12, the second end 282 of each traction cable 28 can be fixed to the corresponding movable cowl 20 by means of a device of variable length, for example an elastic return device such as a spring 208. Providing an elastic return device makes it possible to compensate for part of the distance traveled by the movable cowl 20 between the retracted and deployed positions, when this distance is greater than the stroke required for the first end 280 of the traction cable 28. As can be seen in Figures 12 and 13, the elastic return device is in the retracted position when the thrust reverser system 18 is in the retracted position, and is in the extended position when the thrust reverser system 18 is in the deployed position.Thus, the movable hood 20 is able to move back even after the first end 282 of the traction cable 28 can no longer move back, the traction cable 28 being retained by the connecting rod 26.

[0082] In a variant shown in Figures 13 and 14, the guide device 32 of the traction cable 28 comprises at least one return system 322, 324, fixed relative to the fixed internal structure 160, the return system comprising in the example two pulleys 322, 324.

[0083] In a variant shown in Figures 15 and 16, the pulling system 30 comprises at least one return device 300, comprising in the example a mobile pulley 300, which is fixed relative to the mobile cover 20. The second end 282 of the traction cable 28 is fixed to a fixing support 170 fixed relative to the external fixed structure 162 of the nacelle. Providing a mobile pulley 300 which is fixed relative to the mobile cover 20 makes it possible to reduce the travel of the first end 280 of the traction cable relative to the travel of the mobile cover 20. The mobile pulley 300 can be associated with return pulleys (as shown in Figures 15 and 16) or with a sheath 320 (as shown in Figures 6 to 13).

[0084] In a variant shown in Figures 17 and 18, the pulling system 30 may comprise a spring, such as a gas spring 302. In the example, the gas spring 302 comprises a body 302a, inside which is arranged a movable piston 302b. The body 302a is fixed relative to the internal fixed structure 160, and the pulling cable 28 is connected to the movable piston 302b. Thus, when the movable cover 20 moves back, the movable piston 302b drives the pulling cable 28.

[0085] In a variant shown in Figures 19 and 20, the pulling system 30 comprises a pneumatic cylinder 304. The pneumatic cylinder 304 comprises a body 304a inside which is arranged a movable piston 304b. The body 304a comprises an air inlet 304c and an air outlet 304d, both in fluid communication with the secondary vein. Thus, when the movable cover 20 moves back, the movable piston 304b drives the traction cable 28, under the effect of the static pressure difference existing between the air inlet 304c and the air outlet 304d.

[0086] In a variant shown in [Fig.21], an additional traction cable 29 is provided at the level of at least one or each connecting rod 26 not being associated with one of the first and second traction cables 28. The configuration and operation of the additional traction cables 29 are similar to those described above for the first and second traction cables 28.

Claims

Claims

1. Thrust reversal system (18) for a nacelle (3) of an aircraft turbojet engine (2), the thrust reversal system (18) delimiting a secondary vein (16a) for the passage of a secondary flow of the turbojet engine, the thrust reversal system comprising an internal fixed structure (160) and an external fixed structure (162) connected together at at least one bifurcation (164, 166), the bifurcation (164, 166) being delimited on either side by a bifurcation wall (160a, 160b) formed by the internal fixed structure (160), the thrust reversal system comprising: - at least one movable cowl (20), movable between a retracted position, in which the thrust reversal system (18) is in direct jet configuration, and a deployed position, in which the thrust reversal system (18) is in reverse jet configuration; - a set of air deflection devices (22); - at least one sealing membrane (24), movable between a retracted position corresponding to the retracted position of the movable cover (20), in which it is at least partially housed in an internal space (200) of the movable cover (20), and a deployed position corresponding to the deployed position of the movable cover (20), in which it is at least partially deployed in the secondary vein (16a), so as to divert a majority portion of the secondary flow towards the air diversion devices (22); the sealing membrane (24) being fixed, at rear fixing points (242), to at least one fixing element fixed relative to the external fixed structure (162) and, at front fixing points (240), to deployment devices (26, 28); the deployment devices (26, 28) comprising, for the or each sealing membrane, at least a first traction cable (28) and a second traction cable (28), the first and second traction cables (28) each having a first end (280) connected to the front attachment point (240) of the sealing membrane closest to the wall (160a, 160b) of the bifurcation (164, 166) corresponding to the laying, and a second end (282) located outside the secondary vein (16a) and connected to a pulling system (30), each pulling cable (28) penetrating into the secondary vein (16a) via a respective orifice (160c) provided in the internal fixed structure (160), the pulling system (30) making it possible to pull on the second end (282) of the corresponding pulling cable (28) during deployment of the thrust reverser device, so as to reduce the distance between the first end of the pulling cable (28) and the corresponding passage orifice (160c).

2. Thrust reversal system (18) according to the preceding claim, in which the pulling system (30) comprises a fixing support (206) for the second end (282) of the traction cable (28), the fixing support being fixed relative to the movable cowl (20).

3. Thrust reversal system (18) according to the preceding claim, in which the traction cable (28) is connected to the pulling system (30) by a variable length device, for example an elastic return device (208).

4. Thrust reversal system (18) according to one of the preceding claims, in which the pulling system (30) comprises a return device (300) secured to the movable cowl (20), the second end of the traction cable (28) being secured to a fixing support fixed relative to the external fixed structure (160) of the thrust reversal system (18), the return device (300) comprising for example a pulley (300).

5. A thrust reverser system (18) according to claim 1, wherein the pull system (30) comprises a spring, such as a gas spring, or a pneumatic cylinder.

6. Thrust reversal system (18) according to one of the preceding claims, comprising a guidance system (32) configured to impose the routing of the traction cable out of the secondary vein (16a).

7. Thrust reversal system (18) according to the preceding claim, in which the guidance system (32) comprises at least one return system (322, 324), comprising for example one or more pulleys (322, 324).

8. A thrust reverser system (18) according to claim 6 or 7, wherein the guidance system (32) comprises a sheath (320) into which a portion of the traction cable (28) is inserted.

9. Thrust reversal system (18) according to one of the preceding claims, in which the deployment devices (26, 28) comprise passive deployment devices (26), of fixed length, a first end (260) of which is integral with the internal fixed structure, and a second opposite end (262) is integral with a forward attachment point (240) of the closure membrane (24), the passive deployment devices (26) being for example connecting rods (26) or cables.

10. A thrust reverser system (18) according to the preceding claim, comprising at least one additional traction cable (29), the additional traction cable (29) being associated with one of the passive deployment devices (26) which are not associated with the first and second traction cables (28).

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