Thrust reverser comprising an improved system for deploying a membrane for sealing off the secondary flow path

Abstract

The invention relates to a thrust reverser for an aircraft propulsion assembly, comprising a membrane (58) for sealing off a secondary flow path, as well as at least one deployment connecting rod (62) for deploying this membrane, which is designed to be moved from a first position projecting radially into the secondary flow path when the mobile structure (29) is occupying its advanced direct-thrust position, to a second position folded down toward the downstream direction when the mobile structure is occupying its retracted thrust-reversal position. According to the invention, the reverser also comprises a device (70) for actuating the connecting rod (62), the reverser being configured such that during an initial phase of movement of the mobile structure from its advanced direct-thrust position towards its retracted thrust-reversal position, the actuating device (70) causes a first articulated connection (74a) of the connecting rod to move radially inwards and / or axially upstream.

Description

[0001] DESCRIPTION

[0002] TITLE: THRUST REVERSER INCLUDING AN IMPROVED SYSTEM FOR DEPLOYING A SECONDARY VEIN CLOSURE MEMBRANE

[0003] Technical field

[0004] The invention relates to the field of nacelles and thrust reversers for aircraft propulsion systems, and, more particularly, to systems allowing the deployment of the membranes for closing the secondary vein of a propulsion system.

[0005] State of the prior art

[0006] 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.

[0007] 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.

[0008] To divert at least part of the secondary flow through this passage opening toward the grilles, the inverter is typically equipped with shutters, which, when deployed, at least partially close the secondary stream. This commonly forces the secondary flow air through the passage opening and into the grilles, which then generate the forward counter-thrust airflow. The shutter solution is also known to be relatively heavy and bulky. 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 to both new aircraft types and those already in operation, requiring the implementation of technological solutions to ensure their compliance with current regulations. Civil aviation has been mobilizing for several years now to contribute to the fight against climate change.

[0009] 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.

[0010] With this in mind, solutions have been developed for closing the secondary vein using one or more deployable membranes. Such a membrane design is known, for example, from document FR 3 076 864 Al.

[0011] The deployment of a sealing membrane can be achieved more easily 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.

[0012] As the moving structure moves towards its rearward thrust reversal position, the membrane gradually deploys into the vein, plunging radially inwards, driven by the connecting rod(s) which tilt downstream and also radially inwards.

[0013] In the direct jet position, the end of the membrane connected to the connecting rods is generally clamped between a deflection edge of the fixed structure and an upstream end of the radially internal wall of the movable cowl. While this technical solution is generally satisfactory, during an initial phase of movement of the movable structure from its forward direct thrust position to its rearward thrust reversal position, there is a need to limit the risks of the membrane being pressed against an internal surface of the radially internal wall of the movable cowl. Indeed, such a pressing of the membrane impairs its proper deployment radially inwards and is therefore not desirable.

[0014] Furthermore, still in the direct jet position, the radially external end of each deployment rod is located in close proximity to the upstream end of the radially internal wall of the movable cowl. Their two simultaneous movements are not without risk, and there is therefore also a need to limit possible mechanical interference between the radially external end of each rod and the upstream end of the radially internal wall of the movable cowl, whether during the initial phase of movement of the movable structure towards its rearward thrust reversal position, or during the final phase of movement of the movable structure towards its forward direct thrust position.

[0015] Statement of the invention

[0016] To meet at least partially these needs, 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 crossed by a secondary flow, the reverser also comprising a mobile structure comprising at least one mobile reverser cowl equipped with a radially internal wall participating in the radially external delimiting of the secondary vein, the mobile structure being movable relative to the fixed structure between a forward position of direct thrust, and a retracted position of thrust reversal in which the fixed structure and an upstream end of the retracted radially internal wall of the mobile reverser cowl reveal between them an opening for the passage of air through the secondary vein,the thrust reverser also comprising at least one membrane for closing the secondary flow path, designed to divert at least part of the secondary flow towards the passage opening, as well as at least one deployment rod arranged in the secondary flow path and a first end of which is connected, via a connection point, to a first end of the closing membrane, the membrane deployment rod being designed to be moved from a first position projecting radially into the secondary flow path when the mobile structure occupies its forward direct thrust position, to a second position folded downstream when the mobile structure occupies its rearward thrust reversal position, and vice versa.,

[0017] According to the invention, the reverser also comprises a device for actuating the deployment rod, the device connecting the radially internal delimiting wall of the vein to a second end of the deployment rod opposite the first, by means of a first articulated connection, and the reverser is configured so that during an initial phase of movement of the mobile structure from its forward direct thrust position to its retracted thrust reversal position, the actuating device causes a movement of said first articulated connection of the deployment rod, radially inwards and / or axially upstream.

[0018] Thanks to this particular movement of the deployment rod at the start of the reverser opening phase, which makes it possible to pull the membrane upstream and / or inwards with the effect of detaching it, the risks of unwanted attachment of this membrane to the movable cowl are advantageously reduced, or even harmed. The same applies to the risks of mechanical interference between the deployment rod and the upstream end of the radially internal wall of the movable cowl, both during the initial phase of movement of the movable structure towards its rearward thrust reversal position, and during the final phase of movement of the movable structure towards its forward direct thrust position.

[0019] The invention also falls within the scope of technological research aimed at significantly improving aircraft performance and, in this sense, contributes to reducing their environmental impact, here by the use of lightweight and compact secondary flow blocking membranes. The invention preferably provides at least any one of the following optional technical features, implemented individually or in combination.

[0020] Preferably, the actuating device comprises an actuating member having a first end at which said first articulated connection of the deployment rod is located, as well as a second end opposite the first, connected to the radially internal delimiting wall of the vein by means of a second articulated connection, and in the advanced direct thrust position of the mobile structure, the deployment rod and the actuating member form a projecting angle opening downstream.

[0021] This design also advantageously allows for relative radial displacements to be tolerated between the radially internal and external boundary walls of the vein. These radial displacements can in fact occur depending on the different loading cases of the inverter parts, but also due to the appearance of play in the inverter due to wear of the parts over time.

[0022] Preferably, the actuating device comprises biasing means designed to:

[0023] - forcing the actuating member to tilt around the second articulated connection in a first direction of rotation, said first direction of rotation being such that it causes the first end of the actuating member to tilt upstream during said initial phase of movement of the mobile structure from its forward direct thrust position to its retracted thrust reversal position; and

[0024] - force the deployment rod to tilt relative to the actuating member, around the first articulated connection and in a second direction of rotation opposite to the first direction.

[0025] These forces developed by the stressing means cause the membrane to be in tension, whether in the direct jet position, and / or when opening / closing the diverter. This provides better stability for this membrane.

[0026] Preferably, the biasing means are of passive design, and they comprise elastic return means. Alternatively, they could be controlled means, and activated only during the times when the biasing is desired, for example during the opening and / or closing of the inverter, or only during certain phases of these operations on the inverter. As indicated above, a passive design is nevertheless preferred, also making it possible to generate the desired forces in direct jet, in order to tension the membrane and reinforce its stability in the cavity in which it remains stored.

[0027] A hybrid design is also conceivable, in which elastic means would generate the desired forces, but in combination with control means to adjust the stiffness of these elastic means as required. For example, the stiffness could be adjusted during the opening of the reverser, so that the intensity of the forces generated remains high enough to maintain the desired effect.

[0028] Preferably, the deployment rod and the actuating member together form a three-point mechanical system with respectively the membrane connection point, the first articulated connection as well as the second articulated connection, the reverser being designed so that during the movement of the mobile structure from its forward direct thrust position to its retracted thrust reversal position, a relative movement of the deployment rod relative to the actuating member, around the first articulated connection, occurs beyond a position in which said three points are aligned, up to a mechanical locking position of the rod.

[0029] The locking position of the connecting rod advantageously allows it to keep the membrane deployed in a taut manner, and to resist very high intensity stresses, which would remain extremely difficult to counter using simple elastic return means. This locking position is reached by the three-point mechanical system preferably during a final phase of the movement of the mobile structure, towards its rearward thrust reversal position.

[0030] Preferably, the mechanical system comprises stop means making it possible to maintain this system in the mechanical locking position of the connecting rod.

[0031] According to a first preferred embodiment of the invention, said biasing means comprise: - first elastic return means for forcing the actuating member to tilt around the second articulated connection in the first direction of rotation, said first elastic means preferably comprising a hinge spring or a spring cylinder acting on an arm secured to the actuating member; and

[0032] - second elastic return means for forcing the deployment rod to tilt relative to the actuating member, around the first articulated connection in the second direction of rotation, said second elastic means preferably comprising a hinge spring.

[0033] According to a second preferred embodiment of the invention, said stressing means comprise:

[0034] - third elastic return means;

[0035] - a transmission member, a first end of which is connected to the third elastic means, and a second end of which opposite the first is mounted on the deployment rod, between the first articulated connection and the connection point; and

[0036] - a return pulley around which the transmission member travels, this pulley being arranged in such a way that the third elastic means transmit to the connecting rod, via the transmission member, forces simultaneously forcing the actuating member to tilt around the second articulated connection in the first direction of rotation, and the deployment connecting rod to tilt relative to the actuating member, around the first articulated connection in the second direction of rotation.

[0037] In this second preferred embodiment of the invention, the third elastic means therefore make it possible to act simultaneously on the two articulated connections, for greater compactness of said third stressing means.

[0038] Preferably, in the forward position of direct thrust of the mobile structure, the transmission member, for example in the form of a cable, starts from its second end in the direction of the return pulley, bypassing the first articulated connection on the side of said salient angle.

[0039] Preferably, the fixed structure of the inverter comprises at least one deflection grid arranged, in the forward direct thrust position of the mobile structure, in a cavity of the mobile cowl, being isolated from the secondary flow by the radially internal wall of the inverter cowl. Alternatively, the deflection grid(s) could be integrated into the mobile structure of the inverter, without departing from the scope of the invention. Similarly, it is noted that the grids could be replaced, or provided in combination, with a flexible structure of the membrane type, to redirect the air flow upstream.

[0040] Finally, the invention also relates to a propulsion unit for an aircraft, comprising a turbomachine and a nacelle comprising at least one fan cowl, as well as a thrust reverser as described above.

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

[0042] Brief description of the drawings

[0043] The following detailed description refers to the attached drawings in which:

[0044] [Fig. 1] is a schematic half-view in longitudinal section of a propulsion assembly, including a thrust reverser, shown in direct thrust configuration;

[0045] [Fig. 2] is a schematic half-view in longitudinal section of the reverser equipping the propulsion unit shown in Figure 1, in more detail and presented in the form of a first preferred embodiment of the invention, with the reverser shown in the direct thrust configuration;

[0046] [Fig. 2A] is a schematic half-view of the reverser shown in Fig. 2, shown in an intermediate configuration between the direct thrust configuration and the thrust reversal configuration;

[0047] [Fig. 3] is a schematic half-view of the reverser shown in Fig. 2, shown in the thrust reverser configuration;

[0048] [Fig. 3A] is a schematic half-view similar to that of the preceding figure, with the inverter being presented according to an alternative embodiment;

[0049] [Fig. 4] is a perspective view of the reverser shown in Figures 2 and 3, shown in the direct thrust configuration;

[0050] [Fig. 5] is a perspective view of the reverser shown in Fig. 4, shown in the reverse thrust configuration; [Fig. 6] is a schematic half-view in longitudinal section of a portion of the reverser in the form of an alternative embodiment, with this reverser shown in the direct thrust configuration;

[0051] [Fig. 7] is an axial view of the part of the inverter shown in the preceding figure;

[0052] [Fig. 8] is a schematic half-view of the reverser shown in Fig. 6, shown in the thrust reverser configuration;

[0053] [Fig. 9] is a schematic half-view in longitudinal section of a portion of the reverser in the form of a second preferred embodiment of the invention, with this reverser shown in the direct thrust configuration; and

[0054] [Fig. 10] is a schematic half-view of the reverser shown in Fig. 9, shown in the thrust reverser configuration.

[0055] Detailed description of embodiments

[0056] Figure 1 shows an aircraft propulsion unit 1, having a longitudinal central axis A1.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] Here, the fixed structure 31 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. 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 a so-called "C" architecture, known by the Anglo-Saxon name "C-Duct", or an "O" architecture, known by the Anglo-Saxon name "0-Duct".

[0064] Each movable reverser cowl 33 comprises a radially external wall 50, forming an external aerodynamic surface of the reverser and the nacelle, this surface being matched by the external air. Each cowl 33 also comprises 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 external shell 40 of the intermediate casing. The two walls 50, 52 define a cavity 54 preferably open axially towards the front, at the upstream end of the reverser cowl 33.

[0065] Figure 1 shows the reverser 30 in a direct 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.

[0066] The movable cowl 33 is held in the forward direct thrust position by means for locking this cowl onto the fixed structure 31 of the reverser. These controlled locking means (not shown) are conventional, so they will not be described further. As an indicative example, active locks may be used that are capable of unlocking under load to counter the compressive force of a joint between the movable structure and the deflection edge. This type of lock may in fact overcompress the joint, so that unlocking can then be controlled.

[0067] 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 cavity 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.

[0068] 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, Figure 2A representing an intermediate configuration between the two previous ones, observed during the opening and closing of the reverser.

[0069] In Figure 3, it is shown that the setback internal acoustic panel 52 of the reverser cowls reveals upstream a passage opening 56 of the secondary stream 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 channel an air flow intended to pass through the grilles 32 when the mobile system is in this setback 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. Downstream, the passage opening 56 is delimited in particular by the upstream end 52a of the radially internal wall 52.

[0070] 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.It is however noted that in addition to the possibility of providing several membranes 58, one or more more conventional rigid closure flaps could be provided in association with this / these membranes, for example alternating in the circumferential direction.

[0071] 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.

[0072] It is recalled that in a conventional gate inverter, the mobile structure slides relative to the fixed structure by means of a rail / slide system which guides the mobile structure from front to rear during the opening phase of the inverter, and from rear to front during the closing phase. A backward force applied to the mobile structure of the inverter therefore causes it to move backward, relative to the fixed structure. This force is usually generated by conventional actuators such as cylinders or ball screws.

[0073] Still with reference to figures 1 to 5 representing a first preferred embodiment of the invention, the membrane 58 has two opposite ends, namely a first end 58a connecting to one or more actuating rods 62, as well as a second end 58b connected to a rear frame 60 supporting the grids 32. This support is annular or in the form of an annular section connecting in fact the rear end of several adjacent grids.

[0074] Concerning the first membrane end 58a, it is therefore connected to one or more deployment rods 62 arranged in the secondary vein 21B. These are, for example, several rods 62 which are circumferentially spaced from one another, and which are each connected to the first membrane end 58a via a connection point 63 specific to each rod. However, in the remainder of the description, only one rod will be described, it being understood that the design of the other rods is identical or similar, as is their cooperation with the surrounding elements.

[0075] The connection point 63 thus connects the first membrane end 58a to a first end 62a of the deployment rod 62.

[0076] Furthermore, an actuating device 70, specific to the invention, connects the radially internal delimiting wall 18 of the duct to a second end 62b of the connecting rod, opposite the first end 62a. This device 70, used for actuating the connecting rod 62, will be described below. As can be seen in FIGS. 1, 2 and 4, when the mobile structure 29 occupies its forward direct thrust position, at least a portion of the sealing membrane 58 is arranged radially between the deflection grids 32 and the radially internal wall 52 of the reverser cover 33, in the cavity 54. Preferably, the portion of the membrane 58 which is located in this cavity 54 of the reverser cover 33, radially covers the entire length of the grids 32.As a result, when the mobile structure 29 adopts its forward direct thrust position, the first end 58a of the membrane 58 is pinched between the upstream end of the wall 18, and the deflection edge 46B, close to the connection point 63 which is located in the vein. In order to avoid possible damage to the membrane 58 due to this pinching, the deflection edge 46B may locally have a notch of a shape adapted to receive the upstream end 52a of the wall 52. Thus, the membrane 58 is also pressed into this notch of the deflection edge 46B, by the support of the upstream end of the wall 52.

[0077] Also, as can be seen in Figures 2A and 3, when the mobile structure 29 moves and occupies its rearward thrust reversal position at the end of this movement, the closing membrane 58 is partly in abutment against the upstream end 52a of the radially internal wall 52 of the reverser cowl, therefore 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.

[0078] 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.

[0079] 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 cavity 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.

[0080] Another possibility, not shown, consists of carrying out the radially external attachment of the membrane 58 on the radially external wall 50 of the sliding cover 33.

[0081] As indicated previously, the connecting rod actuating device 70 connects the radially internal delimiting wall 18 of the vein (also called IFS, from the English “Inner Fixed Structure”), to the second end 62b of the connecting rod, corresponding to the radially internal end in the direct thrust configuration. The device 70 and the reverser assembly are designed so that the connecting rod 62 is moved from a first position projecting radially into the secondary vein when the mobile structure 29 occupies its forward direct thrust position, to a second position folded downstream when the mobile structure 29 occupies its rearward thrust reversal position, and vice versa.In the first position shown in Figure 2, the connecting rod 62 can in fact adopt a radial or substantially radial orientation in the vein 21B, a slight inclination relative to this radial direction nevertheless remaining possible, for example up to a value of 10 to 20°. The connecting rod 62 has a substantial length, for example greater than half the radial thickness of the vein 21B at the location where the connecting rod is located, and even more preferably of a length greater than two-thirds of this radial thickness.

[0082] The actuating device 70 firstly comprises an actuating member 72, in the form of a connecting rod or clevis, having a first end 72a at which is located a first articulated connection 74a with the second connecting rod end 62b. This first articulated connection 74a preferably has a pivot / rotation axis of circumferential, or substantially circumferential, orientation. A second end 72b of the member ni, opposite the first end 72a, is connected to the radially internal delimiting wall 18 by means of a second articulated connection 74b, preferably with a pivot / rotation axis parallel or substantially parallel to that of the first articulated connection 74a. To do this, a fitting 64 is secured to the fixed wall 18, and forms the second articulated connection 74b with the second end 72b of the member 72.

[0083] It is noted that in the direct thrust configuration, the connecting rod 62 and the actuating member 72 form a salient angle B1 opening downstream, this angle B1 being high and preferably between 150 and 175°. To do this, the member 72 also has a substantially radial orientation in this direct thrust configuration.

[0084] The connecting rod 62 and the member 72 together form a three-point mechanical system with respectively the membrane connection point 63, the first articulated connection 74a, and the second articulated connection 74b. This three-point mechanical system, comparable to a “knee” type articulation, is such that during the movement of the mobile structure 29 from its forward direct thrust position to its rearward thrust reversal position, there is a relative movement of the connecting rod 62 relative to the actuating member 72 around the first articulated connection 74a, which leads at least initially to a reduction in the salient angle B1, as can be seen in FIG. 2A. The mechanical system then tends to fold back.

[0085] To promote the folding of this three-point mechanical system when opening the reverser, preferably passive biasing means are provided, which firstly comprise first elastic return means 80a, shown only schematically by an arrow in the relevant figures. These first means 80a, for example of the hinge spring type, force the member 72 to tilt around the second articulated connection 74b in a first direction of rotation, corresponding to the counterclockwise direction in the figures. This first direction of rotation is such that it causes the first end 74a of the member 74 to tilt upstream and radially inwards during an initial phase of movement of the mobile structure 29 from its forward direct thrust position to its retracted thrust reversal position.The passive biasing means also comprise second elastic return means 80b, shown only schematically by an arrow in the relevant figures. These second means 80b, for example also of the hinge spring type, force the connecting rod 62 to tilt relative to the member 72 around the first articulated connection 74a, in a second direction of rotation opposite to the first direction, and therefore corresponding to the clockwise direction in the figures.

[0086] Also, thanks to all of the elements described above which form the reverser, the latter makes it possible to ensure that during the initial phase of movement of the mobile structure 29 from its forward direct thrust position to its retracted thrust reversal position, the actuating device 70 causes a movement, via its member 74, of the first articulated connection 74a radially inwards and / or axially upstream.

[0087] By pulling in this way on the connecting rod 62 at the start of the reverser opening, it is advantageously prevented that the membrane 58 which begins to deploy in the vein 21B comes to press against the radially internal surface of the wall 52 of the cover 33, moving towards the rear. Thus, instead of a simple pivoting of the connecting rod 62 relative to the wall 18 at its second end 62b, the latter is moved with the first connection 74a upstream and towards the inside by the device 70, in order to cause a sort of detachment of the membrane. The deployment of this membrane 58 is thus significantly improved and made more reliable.

[0088] Furthermore, thanks to the presence of the first and second elastic return means 80a, 80b, these exert forces on the membrane 58 even in the direct thrust configuration. This makes it possible to keep this membrane in tension when it is stored in the hood cavity 54, and thus contributes to its stability and to facilitate its deployment during a subsequent operation of opening the reverser. Also, the three-point mechanical system and its associated elastic return means 80a, 80b make it possible to tolerate, if necessary, relative radial displacements between the two walls 18, 52 in the direct thrust configuration. As the mobile structure 29 moves rearward, the connecting rod 62 continues to fold downstream and the member 72 continues to fold upstream, with the consequence of a reduction in the salient angle B1 between these two elements.In this regard, it is noted that the first elastic return means 80a are dimensioned so as to generate on the second end 72b of the member 72 a moment of sufficient intensity to counter the opposite moment, applied via the connecting rod 62 at its first end 72a, by the membrane 58 inflating with air in the vein 21B.

[0089] The second elastic means 80b, by virtue of their direction of stress, contribute to plunging the first end of the membrane 58a towards the inside of the vein 21B, so that it takes in air and gradually unfolds there.

[0090] Another advantage associated with the presence of the elastic return means 80a, 80b lies in easy detection, during the maintenance phase, of a possible connection problem between the first membrane end 58a and the connecting rod(s) 62. Indeed, usually, this type of detection proves to be particularly complicated due to the difficult visual access to this junction. In the proposed design, any connecting rod 62 subject to a connection fault to the membrane 58 will automatically fold back into the vein 21B in its second position folded down downstream, under the combined action of the elastic return means 80a, 80b. Such a connecting rod folded down into the vein 21B remaining easily identifiable by an operator carrying out maintenance operations, the aforementioned detection proves to be effectively simplified.

[0091] As indicated previously, during the opening of the reverser, the three-point mechanical system folds back with the consequence of the progressive reduction of the salient angle B1, until for example it becomes zero at the end of opening, as can be seen in Figures 3 and 3A. In this configuration where the connecting rod 62 adopts its second position folded downstream, the three points are aligned or substantially aligned, with the second articulated connection 74b located between the first articulated connection 74a and the connection point 63. This alignment occurs parallel or substantially parallel to the axial direction of the reverser. According to an alternative shown in Figures 6 to 8, the first and second elastic return means 80a, 80b force, at the end of the reverser opening operation, the movement of the connecting rod 62 beyond the position in which said three points are aligned.Thus, after being zero, the salient angle B1 reverses to give rise to another salient angle B2 shown in Figure 8, placing the three-point mechanical system in a position of mechanical locking of the connecting rod 62. This angle B2, also open upstream but this time with the connecting rod 62 located radially inwards relative to the member 72, can remain small, for example less than 20°.

[0092] Once past the three-point alignment position, the connecting rod 62 cannot pivot counterclockwise relative to the member 72, as long as the movable cover 33 is not moved upstream again following a closing command from the reverser. The locking position of the connecting rod 62 advantageously allows it to keep the membrane 58 deployed in a taut manner, and to withstand very high intensity stresses, which would remain extremely difficult to counter using simple elastic return means.

[0093] In this alternative, the design of the first elastic return means 80a can be modified, by providing a spring cylinder. This cylinder 82 comprises a cylinder body 84 mounted articulated on the wall 18, and a movable cylinder rod 86. At its end, the rod 86 is articulated on the end of an arm 88 secured to the actuating member 72. Inside the cylinder 82, a spring 90 forces, via the rod 86 on which it acts, to pivot the arm 88 and the member 72 in the second counterclockwise direction. The arm 88 and the actuating member 72 together form a mechanical return bell crank.

[0094] At the level of the articulation with the jack rod 86, the end of the arm 88 advantageously serves as a stop against the wall 18. This stop makes it possible to maintain the mechanical system in the locking position, despite the forces which continue to be generated by the first elastic return means 80a, via the compression spring 90.

[0095] Whatever the design adopted for the first and second elastic return means 80a, 80b, these preferably make it possible to generate the aforementioned forces throughout the opening phase of the reverser. By construction, these forces can be made to decrease as this opening occurs, due to the progressive unloading of the springs.

[0096] It is noted that during a reverser closing operation, reverse movements occur for the connecting rod 62 and the actuating member 72, leading at the same time to the loading of the first and second elastic return means 80a, 80b. In the final phase of a reverser closing operation, the particular kinematics applied by the actuating device 70 also avoids the risks of mechanical collision between the first end of the connecting rod 62a, and the upstream end 52a of the acoustic wall 52.

[0097] According to a second preferred embodiment shown in Figures 9 and 10, the biasing means comprise third elastic means which make it possible to generate the same functions as those of the first and second elastic means 80a, 80b of the first preferred embodiment described previously.

[0098] The third elastic return means 80c comprise a hollow body 92 fixed to the wall 18. Inside this body, there is provided a compression spring 94 bearing at one of its ends against one end of the body 94, and bearing at the other of its ends on a seat 96 movable in translation inside the body, preferably in the axial direction or substantially in this direction.

[0099] A transmission member, of the cable type 98, comprises a first end 98a connected to the third elastic means 80c, being connected to the movable seat 96. Its second end 98b, opposite the first, is mounted on the deployment rod 62, at a point 100 between the first articulated connection 74a and the connection point of the membrane (not visible in figures 9 and 10).

[0100] A return pulley 102 is also provided around which the cable 98 runs, between its two ends 98a, 98b. This pulley 102 is arranged so that in the first projecting position of the connecting rod 62, occupied in the direct thrust configuration shown in FIG. 9, the cable 98 leaves from its second end 98b in the direction of the return pulley 102, but bypassing the first articulated connection 74a against which this cable 98 bears. The cable is bypassed on the side where the projecting angle B1 opens, that is to say downstream of the first connection 74a. Also, in this configuration, a part of the cable 98 forms a V open towards the upstream with a rounded tip at the level of the support against the first articulated connection 74a. Then, the cable winds around the pulley 102 located in the upstream continuity of the spring 94, to join the seat 96 by crossing the spring 94.

[0101] Thanks to this design, the third elastic means 80c transmit to the connecting rod 62, via the cable 98, forces simultaneously forcing the member 72 to tilt around the second articulated connection 74b in the first direction of rotation, and the connecting rod 62 to tilt relative to the member 72 around the first articulated connection 74a, in the second opposite direction.

[0102] In the thrust reversal configuration shown in Figure 10, where the spring 94 is further relaxed and unloaded, the cable 98 is located axially downstream of the first articulated connection 74a, simply wrapping around the return pulley 102.

[0103] Various modifications may be made by those skilled in the art to the invention just 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, if the preferred embodiments described above relate to a reverser design with fixed deflection grids, these grids may alternatively be integrated into the mobile structure of the reverser.

Claims

CLAIMS 1. 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 mobile structure (29) comprising at least one mobile reverser cowl (33) equipped with a radially internal wall (52) participating in the radially external delimiting of the secondary vein (21B), the mobile structure being movable relative to the fixed structure between a forward direct thrust position, and a rearward thrust reversal position in which the fixed structure and an upstream end (52a) of the rearward radially internal wall of the mobile reverser cowl reveal between them an opening (56) for the passage of air through the secondary vein,the thrust reverser also comprising at least one membrane (58) for closing the secondary flow path, designed to divert at least part of the secondary flow towards the passage opening (56), as well as at least one deployment rod (62) arranged in the secondary flow path and a first end (62a) of which is connected, via a connection point (63), to a first end (58a) of the closing membrane, the membrane deployment rod being designed to be moved from a first position projecting radially into the secondary flow path when the mobile structure (29) occupies its forward direct thrust position, to a second position folded downstream when the mobile structure occupies its retracted thrust reversal position, and vice versa, characterized in that the reverser also comprises a device (70) for actuating the deployment rod (62),the device connecting the radially internal delimiting wall (18) of the vein to a second end (62b) of the deployment rod opposite the first, by means of a first articulated connection (74a), and in that the reverser is configured so that during an initial phase of movement of the mobile structure from its advanced direct thrust position to its retracted thrust reversal position, the actuating device (70) causes a movement of said first articulated connection (74a) of the deployment rod, radially inwards and / or axially upstream., 2. Thrust reverser according to claim 1, characterized in that the actuating device (70) comprises an actuating member (72) having a first end (72a) at which said first articulated connection (74a) of the deployment rod is located, as well as a second end (72b) opposite the first, connected to the radially internal delimiting wall (18) of the vein by means of a second articulated connection (74b), and in that in the advanced direct thrust position of the mobile structure (29), the deployment rod (62) and the actuating member (72) form a salient angle (Bl) opening downstream.

3. Thrust reverser according to claim 2, characterized in that the actuating device (70) comprises biasing means (80a, 80b, 80c, 98, 102) designed to: - forcing the actuating member (72) to tilt around the second articulated connection (74b) in a first direction of rotation, said first direction of rotation being such that it causes the first end (72a) of the actuating member to tilt upstream during said initial phase of movement of the mobile structure (29) from its forward direct thrust position to its rearward thrust reversal position; and - force the deployment rod (62) to tilt relative to the actuating member (72), around the first articulated connection (74a) and in a second direction of rotation opposite to the first direction.

4. Thrust reverser according to claim 3, characterized in that the biasing means are of passive design, and they comprise elastic return means (80a, 80b, 80c).

5. Thrust reverser according to any one of claims 2 to 4, characterized in that the deployment rod (62) and the actuating member (72) together form a three-point mechanical system with respectively the connection point (63) of the membrane (58), the first articulated connection (74a) as well as the second articulated connection (74b), the reverser being designed so that during the movement of the mobile structure from its forward direct thrust position to its retracted thrust reversal position, a relative movement of the deployment rod (62) relative to the actuating member (72), around the first articulated connection (74a), occurs beyond a position in which said three points are aligned, up to a mechanical locking position of the rod.

6. Thrust reverser according to claim 5, characterized in that the mechanical system comprises stop means making it possible to maintain this system in the mechanical locking position of the connecting rod (62).

7. Thrust reverser according to any one of the preceding claims combined with claim 3, characterized in that said biasing means comprise: - first elastic return means (80a) for forcing the actuating member (72) to tilt around the second articulated connection (74b) in the first direction of rotation, said first elastic means preferably comprising a hinge spring or a spring cylinder (82) acting on an arm (88) secured to the actuating member (72); and - second elastic return means (80b) for forcing the deployment rod (62) to tilt relative to the actuating member (72), around the first articulated connection (74a) in the second direction of rotation, said second elastic means preferably comprising a hinge spring.

8. Thrust reverser according to any one of claims 1 to 6 combined with claim 3, characterized in that said biasing means comprise: - third elastic return means (80c); - a transmission member (98) of which a first end (98a) is connected to the third elastic means (80c), and of which a second end (98b) opposite the first is mounted on the deployment rod (62), between the first articulated connection (74a) and the connection point (63); and - a return pulley (102) around which the transmission member (98) travels, this pulley being arranged so that the third elastic means (80c) transmit to the connecting rod (62), via the transmission member (98), forces simultaneously forcing the actuating member (72) to tilt around the second articulated connection (74b) in the first direction of rotation, and the deployment connecting rod (62) to tilt relative to the actuating member (72) around the first articulated connection (74a), in the second direction of rotation.

9. Thrust reverser according to claim 8, characterized in that in the forward direct thrust position of the mobile structure (29), the transmission member (98), for example in the form of a cable, extends from its second end (98b) in the direction of the return pulley (102) bypassing the first articulated connection (74a) on the side of said salient angle (Bl).

10. Propulsion assembly (1) for aircraft, comprising a turbomachine (2) and a nacelle (3) 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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