Thrust reverser with sealing diaphragm and retention system

Abstract

Thrust reverser with shut-off membrane and retention system. Thrust reverser (1) for an aircraft propulsion system, the thrust reverser (1) comprising a fixed structure (3), a movable structure (13) transversable relative to the fixed structure (3) between a thrust position and a thrust reversal position, at least one shut-off membrane (17) designed to deflect at least a portion of the secondary flow outwards, at least one retention system (21) designed to cooperate with the fixed structure (3) and the corresponding shut-off membrane (17), said retention system (21) being configured to subject the corresponding shut-off membrane (17) to a restoring force comprising a component opposite to the general flow direction in the thrust reversal position. Figure 2

Description

Title of the invention: Thrust reverser with sealing membrane and retention system Scope of the invention

[0001] The present invention relates to a thrust reverser with a sealing diaphragm and a system for retaining the sealing diaphragm. The retention system applies to the sealing diaphragm a force comprising a component opposite to a general direction of flow of an aircraft propulsion system. Previous art

[0002] A thrust reverser of an aircraft propulsion assembly comprises a fixed structure and a movable structure or assembly of at least one cowling intended, in a thrust reversal position, to move longitudinally to provide a radial opening in the nacelle.

[0003] A set of thrust reverser actuators, similar to that described in document FR 3 010 455, allows the passage from a thrust position, or operating position of the propulsion assembly in flight, to the thrust reversal position, or position of redirection of a part of the gases moving in the propulsion assembly in the opposite direction through the radial opening.

[0004] The radial opening allows gases flowing in a secondary stream of the propulsion assembly to escape to the outside. The thrust reverser further includes a deflector extending transversely in the secondary stream to guide the gases outwards in the thrust reversal position.

[0005] The deflector can be a flap, connected to the fixed structure by a connecting rod and to the moving structure by a rotating link, deploying as the moving structure moves from a thrust position to the thrust reversal position.

[0006] However, this technical solution requires the use of different parts representing a certain mass and the functional clearances between these parts are likely to disturb the aerodynamics of the gas flow in the propulsion assembly.

[0007] An alternative is to use as a deflector a membrane that unfolds like a sail when the thrust reversal position is reached. This sealing membrane is flexible and unfolds by being attached to the fixed structure on one side and to the moving structure on the other, as described in document FR 3 131 757.

[0008] The sealing membrane is in contact with certain parts of the moving structure and exerts axial forces along the general direction of flow on the moving structure. The use of the sealing membrane therefore necessitates an oversizing of the set of actuators to allow the movement of the mobile structure from the thrust reversal position to the thrust position if we compare the diaphragm system to the flap system.

[0009] There is therefore a need to improve the functioning of the sealing membrane. Description of the invention

[0010] To this end, the present invention relates to a thrust reverser for an aircraft propulsion system, the thrust reverser comprising:

[0011] a fixed structure provided with a front frame and an internal boundary wall for a secondary flow of the propulsion assembly, the secondary flow being intended to be traversed by a secondary flow in a general direction of flow,

[0012] a movable structure having at least one hood, the movable structure being translationally movable relative to the fixed structure along a longitudinal central axis of the thrust reverser between a thrust position and a thrust reversal position,

[0013] at least one sealing membrane designed to deflect at least a portion of the secondary flow outwards through a radial opening formed between the front frame and the moving structure in the thrust reversal position, the at least one sealing membrane extending into the secondary flow in the thrust reversal position,

[0014] at least one retention system designed to cooperate with the fixed structure and the corresponding sealing membrane, said retention system being configured to subject the corresponding sealing membrane to a restoring force comprising a component opposite to the general direction of flow in the thrust reversal position.

[0015] During the transition from the thrust position to the thrust reversal position, the radial opening appears until it reaches its maximum size in the thrust reversal position.

[0016] At the same time, the sealing membrane unfolds and is subjected to the secondary flow which imposes a force on it comprising a component in the general direction of flow.

[0017] The sealing membrane, as it deploys in the secondary vein, is pressurized by the gas flow. The orientation of the resultant force evolves throughout the transit to become predominantly axial, that is, in the general direction of flow, in the thrust reversal position. The vein is axially obstructed by the sealing membrane, with the flow being deflected predominantly radially just upstream of the sealing membrane in the thrust reversal position.

[0018] The sealing membrane can then come to rest against the moving structure and risk of in turn imposing a force on the moving structure in the general direction of flow.

[0019] The retention system(s) make it possible to limit the movement of the corresponding sealing membrane in the general direction of flow and thus to avoid or limit the stress of the sealing membrane on the moving structure.

[0020] A sealing membrane may have one or more retention systems depending on the configurations.

[0021] In the present text the terms upstream, downstream, front, rear are defined with respect to the general direction of flow.

[0022] According to one aspect of the invention, said retention system is also configured to subject the corresponding sealing membrane to the restoring force between an intermediate starting restore position and the thrust reversal position.

[0023] Thus, the restraint system is not active (no restoring force with a component opposite to the general flow direction) in the thrust position. The restraint system only activates from the intermediate starting position of the restoring force.

[0024] Preferably, the intermediate starting position of the return corresponds to 50% or more, and preferably to 70% or more, of a stroke between the push position and the push reversal position.

[0025] According to one aspect of the invention, the fixed structure comprises a back frame, at least one sealing membrane having a first end fixed on or cooperating with the back frame,

[0026] each cowling includes an external boundary wall configured to delimit the secondary duct with the internal boundary wall in the thrust position and an external panel having an external aerodynamic surface of the thrust reverser,

[0027] each hood has an open cavity in the direction of the front frame in the push position and provided between the external boundary wall and the external panel, the rear frame being located in the cavity in the push position so that at least one sealing membrane is at least partly in the cavity in the push position.

[0028] It appears that during the deployment and withdrawal of the obturator membrane between the push position and the push reversal position, the obturator membrane comes out of the cavity and then goes back in.

[0029] This arrangement promotes the circulation of gas in the secondary vein in the thrust position.

[0030] According to one aspect of the invention, at least one sealing membrane is configured to cooperate by contact with an upstream end of the external boundary wall at least over a portion of a thrust reverser stroke between the position of thrust and thrust reversal position.

[0031] Due to the circulation of gas in the general direction of flow, the sealing membrane is constrained towards the rear frame and comes into contact with the external boundary wall, particularly in an initial part of the stroke between the thrust position and the thrust reversal position.

[0032] During this contact, the sealing membrane imposes a stress on the moving structure, with a component along the general flow direction. This stress corresponds to the interaction between the sealing membrane and the upstream end of the external boundary wall. The upstream end pushes the sealing membrane in the opposite direction to the general flow direction. The sealing membrane is thus stretched and rubs against the upstream end in the same way that a belt or cable rubs against a pulley, thereby pushing the moving structure downstream.

[0033] This constraint is reduced or eliminated by the restraint system. Over at least part of the thrust reverser stroke, the sealing diaphragm is in contact with the external boundary wall, but the applied force is less.

[0034] Depending on the design, the retention system can also cause a separation over part of the stroke between the thrust position and the thrust reversal position. During this separation, no stress is imposed by the sealing membrane on the moving structure.

[0035] The sealing membrane can be made of a material known to those skilled in the art for this type of application. For example, it can be an unimpregnated fabric, such as aramid fibers. The sealing membrane can also be made of a composite material with a particularly flexible matrix, such as aliphatic polyurethane or silicone. In this case, the matrix provides low flexural strength, and the resulting structure behaves like a membrane.

[0036] According to one aspect of the invention, the sealing membrane is configured to fold in a perfectly reversible manner. Preferably, this folding can correspond to an elastic extension or to fiber sliding of the sealing membrane.

[0037] In particular, the folding of the sealing membrane has a very small radius of curvature compared to the surface of the sealing membrane.

[0038] According to one aspect of the invention, the sealing membrane has a very small thickness compared to its surface area. For example, the thickness is on the order of 0.1 to 3 mm. For information purposes, it is observed that the sealing membrane behaves like a boat sail when it is under pressure.

[0039] The external boundary wall is an acoustic panel or sliding panel of the transcowl.

[0040] According to one aspect of the invention, each restraint system comprises an element of connection configured to cooperate with a corresponding fixing point of the fixed structure on one hand and configured to cooperate with the corresponding sealing membrane at an attachment point on the other hand, the attachment point being in the cavity in the push position.

[0041] Preferably, the attachment point is located on the front frame.

[0042] This arrangement allows the sealing membrane to be subjected to a restoring force in the opposite direction to the general flow direction by a simple mechanism for fixing the sealing membrane to the front frame via a connecting element.

[0043] According to one aspect of the invention, the connecting element is configured to be included in a space delimited by the cavity and the front frame in the push position so as to be outside the secondary vein.

[0044] This configuration of the linking element in the thrust position avoids any disturbance of the secondary flow circulation and thus any imbalance of the engine assembly.

[0045] According to one aspect of the invention, in the push position, the first end is located in the cavity so that the sealing membrane is at least partly in contact with the external boundary wall inside the cavity, the hook point being located at a determined distance from the first end, the determined distance defining an intermediate position of total detachment of the sealing membrane from the external boundary wall which is located between the push position and the push reversal position, the sealing membrane no longer being in contact with the external boundary wall from the intermediate detachment position.

[0046] In other words, between the intermediate detachment position and the thrust reversal position, the sealing membrane is no longer in contact with the moving structure thanks to the action of the connecting element.

[0047] At the end of the opening of the mobile structure, the sealing membrane does not disturb the movement of the mobile structure, which requires less effort to move the mobile structure at the end of opening and at the beginning of closing.

[0048] During closure towards the thrust position, the sealing membrane comes into contact with the external boundary wall in the intermediate separation position. It should be noted that the forces exerted by the sealing membrane on the external boundary wall are, however, limited by the action of the connecting element which retains the sealing membrane upstream.

[0049] This arrangement thus facilitates the movement of the mobile structure which is little disturbed by the presence of the sealing membrane.

[0050] The determined distance defines the stage of opening of the mobile structure from whereby the connecting element is stretched and applies a restoring force on the sealing membrane.

[0051] The greater the determined distance, the earlier the restoring force on the sealing membrane appears. One possibility is to define a force corresponding to an opening of approximately 80%. A more premature activation of the connecting element is on the order of 70% of the opening.

[0052] The tensioning by the connecting element does not necessarily correspond to the moment when the sealing membrane ceases to be in contact with the moving structure. The sealing membrane may be taut and still in contact with the moving structure, then detach completely from the moving structure as the opening progresses.

[0053] According to one aspect of the invention, the connecting element is dimensioned to extend in a straight line between the attachment point and the fixing point in the push position.

[0054] This dimensioning of the connecting element allows it to be held inside the cavity in the thrust position.

[0055] According to one embodiment, the connecting element may have a length greater than a straight-line distance between the attachment point and the fixing point in the thrust position. The connecting element is then relaxed in the thrust position and at the beginning of its transit towards the thrust reversal position.

[0056] The length of the connecting element thus also has an influence on the stage of opening of the mobile structure from which the connecting element becomes tense.

[0057] According to one aspect of the invention, the retention system further comprises an elastic retention device configured to apply a restoring force to the connecting element towards the attachment point.

[0058] This arrangement makes it possible to reduce the force applied by the sealing membrane on the moving structure by retaining the connecting element more upstream.

[0059] According to one possibility, the elastic retaining device is an elastic piece connecting the front frame to the connecting element. The elastic piece may be a cord made of an elastic material fixed to the fixed part, in particular to the front frame, and to the connecting element.

[0060] The elastic part is configured to expand as the moving structure opens. This gradually and then completely detaches the sealing membrane from the moving structure.

[0061] According to another possibility, the elastic retention device is a winder attached to or formed in the front frame. The winder includes a return spring sized to allow the progressive detachment of the sealing membrane from the The structure moves when opening. As an alternative to a spring, a motor, for example an electric one, can be used as a restoring force.

[0062] According to one aspect of the invention, the connecting element is a cable or strap of fixed length. Alternatively, other devices could be used as long as they fulfill the function of connecting the front frame and the shutter membrane.

[0063] According to one aspect of the invention, the retention system also includes a reinforcement element configured to link the linking element to the sealing membrane in a reinforcement location separate from the attachment point.

[0064] This arrangement ensures that the connecting element is correctly attached to the sealing membrane. Furthermore, the reinforcement location, separate from the attachment point, allows the shape of the sealing membrane in the thrust reversal position to be defined more precisely than with the attachment point alone.

[0065] According to one aspect of the invention, the reinforcing element is a cable or strap made of the same material as the connecting element and connected to the latter.

[0066] According to one aspect of the invention, each sealing membrane comprises a second end opposite to the first end and connected to the internal boundary wall by a corresponding connecting rod or other mechanical system, the connecting rod or other mechanical system being configured to move the second end between a low position near or in contact with the internal boundary wall in thrust reversal position and a high position near or in contact with the external boundary wall in thrust position.

[0067] In the lower position, the obturator membrane extends in the secondary vein at least partly transversely to the general direction of flow over almost all or all of the flow section, while in the upper position the obturator membrane is almost or totally no longer present in the secondary vein and has entered the cavity.

[0068] According to one aspect of the invention, the other mechanical system may include an arrangement of cables and corresponding guides connecting the second end to the fixed structure, said arrangement being configured to be set in motion by the movement of the mobile structure between the push position and the push reversal position.

[0069] According to one aspect of the invention, each connecting rod has a lower end configured to be mounted on the internal boundary wall, preferably via a pivot or ball joint.

[0070] Each connecting rod is designed to move from the upper position in which said connecting rod protrudes radially into the secondary vein to the lower position in which said connecting rod is folded downwards.

[0071] In the upper position, each connecting rod can adopt a radial or directional orientation eminently radial in relation to the longitudinal central axis of the thrust reverser, while in the low position, each connecting rod can adopt an axial or substantially axial orientation.

[0072] Each connecting rod includes a return mechanism configured to apply a force tending to tilt said connecting rod towards the lower position. This ensures proper seating of the sealing diaphragm during the transition to the thrust reversal position.

[0073] The connecting rods are spaced circumferentially from each other within the secondary vein, and their number can vary, for example, from two to ten, depending on the angular extent of the obturation membrane.

[0074] According to one aspect of the invention, the mobile structure is configured to slide relative to the fixed structure by means of a rail-slide system of the thrust reverser, the rail-slide system being configured to guide the mobile structure from front to back during the opening phase of the reverser until the thrust reversal position, and from back to front during the closing phase until the thrust position, the thrust reverser comprising a set of actuators provided in the fixed structure to move the mobile structure relative to the fixed structure.

[0075] According to one aspect of the invention, the actuator assembly is configured to be set in motion by at least one cylinder of the thrust reverser associated with a flexible shaft of the thrust reverser. A dedicated control assembly of the thrust reverser controls the at least one cylinder and the actuator assembly.

[0076] The use of the retention system makes it possible to avoid oversizing at least one cylinder. Indeed, without a retention system, the sealing membrane is in contact with the external boundary wall, which creates resistance to the movement of the mobile structure, particularly at the end of the opening and during the closing of the mobile structure.

[0077] According to one aspect of the invention, the thrust reverser comprises at least one set of deflection grids or equivalent deflector device such as a set of deflector sails having an angular amplitude identical or similar to that of the corresponding cowling. The grid assembly is fixed and extends between the front frame and the rear frame.

[0078] According to one aspect of the invention, the mobile structure comprises two hoods. Preferably, each hood forms a complementary hemispherical half-shell so as to define a portion of the gondola.

[0079] According to one possibility, a single sealing membrane is associated with each thrust reverser cover.

[0080] According to another possibility, several circumferentially adjacent sealing membranes are associated with each of the two hoods.

[0081] The various aspects defined above, which are not incompatible, can be combined. Brief description of the figures

[0082] The invention will be better understood with the aid of the detailed description set out below in relation to the accompanying drawings.

[0083] [Fig-1] is a schematic longitudinal sectional view of a thrust reverser with a sealing diaphragm.

[0084] [Fig.2] is a schematic longitudinal sectional view of the thrust reverser in thrust position with a sealing membrane retention system.

[0085] [Fig.3] is a schematic longitudinal sectional view of the thrust reverser between the thrust position and a thrust reversal position.

[0086] [Fig.4] is a schematic longitudinal sectional view of the thrust reverser in thrust reverser position.

[0087] [Fig.5] is a schematic longitudinal sectional view of the thrust reverser with an elastic retaining device.

[0088] [Fig.6] is a schematic longitudinal sectional view of the thrust reverser with a winder as an elastic retaining device.

[0089] [Fig.7] is a schematic longitudinal sectional view of the thrust reverser with the retaining system including a reinforcing element.

[0090] [Fig.8] is a perspective view of a front frame of the thrust reverser, a sealing membrane and retaining systems in thrust reversal position.

[0091] [Fig.9] is a perspective view of a cylinder and a set of actuators of the thrust reverser. Description with reference to the figures

[0092] In the detailed description that will follow of the figures defined above, the same elements or elements fulfilling identical functions may retain the same references in order to simplify the understanding of the invention.

[0093] As illustrated in [Fig.1], a thrust reverser 1 for an aircraft propulsion unit comprises a fixed structure 3 provided with a front frame 5 and an internal boundary wall 7 of a secondary flow 9 of the propulsion unit, the secondary flow 9 being intended to be traversed by a secondary flow in a general flow direction 11.

[0094] The thrust reverser 1 comprises a movable structure 13 having at least one hood 14, the movable structure 13 being movable in translation relative to the fixed structure 3 along a longitudinal central axis 15 of the thrust reverser 1 between a thrust position illustrated in Figures 2, 5 and 6 and a thrust reversal position illustrated in Figures 4, 7 and 8.

[0095] Preferably, the movable structure comprises two hoods 14, each hood 14 forming a complementary hemispherical half-shell so as to define a portion of the gondola.

[0096] According to one possibility, a single sealing membrane 17 is associated with each hood 14 of the thrust reverser 1.

[0097] According to another possibility, several circumferentially adjacent sealing membranes 17 are associated with each of the two hoods 14.

[0098] Furthermore, the thrust reverser 1 includes at least one sealing membrane 17 designed to deflect at least a part of the secondary flow outwards through a radial opening 19 provided between the front frame 5 and the moving structure 13 in the thrust reversal position, the at least one sealing membrane 17 extending into the secondary vein 9 in the thrust reversal position.

[0099] As illustrated in Figures 2 to 9, the thrust reverser 1 further includes at least one retaining system 21 designed to cooperate with the fixed structure 3 and the corresponding sealing membrane 17.

[0100] Said retention system 21 is configured to subject the corresponding sealing membrane 17 to a restoring force comprising a component opposite to the general direction of flow 11 in thrust reversal position and between the thrust reversal position and the thrust position.

[0101] During the transition from the thrust position to the thrust reversal position, the radial opening 19 appears until it reaches its maximum size in the thrust reversal position.

[0102] At the same time, the sealing membrane 17 unfolds and is subjected to the secondary flow which imposes a force on it in the general direction of flow 11. The sealing membrane 17 can then come to rest against the movable structure 13 as illustrated in figures 1 and 3.

[0103] A sealing membrane 17 can have several retention systems 21 depending on the configurations as illustrated in [Fig.8].

[0104] In the present text the terms upstream, downstream, front, rear are defined in relation to the general direction of flow 11.

[0105] The retention system 21 is also configured to submit the corresponding sealing membrane 17 to the restoring force between an intermediate starting restore position and the thrust reversal position.

[0106] Thus, the retaining system 21 is not active in the push position, that is to say there is no restoring force with a component opposite to the general direction of flow 11.

[0107] The restraint system 21 is activated only from the intermediate recoil start position. Preferably, the intermediate recoil start position cor corresponding to 50% or more, and preferably 70% or more, of a stroke between the push position and the push reversal position.

[0108] The fixed structure 3 comprises a back frame 23, at least one sealing membrane 17 having a first end 25 fixed on or cooperating with the back frame 23.

[0109] Each cowling 14 includes an external boundary wall 27 configured to delimit the secondary duct 9 with the internal boundary wall 7 in the thrust position and an external panel 29 having an external aerodynamic surface of the thrust reverser 1.

[0110] Each hood 14 has a cavity 31 open towards the front frame 5 in the push position and provided between the external boundary wall 27 and the external panel 29, the rear frame 23 being located in the cavity 31 in the push position so that at least one sealing membrane 17 is at least partly in the cavity 31 in the push position and cooperates by contact with an upstream end 33 of the external boundary wall 27 at least over a part of a stroke of the thrust reverser 1 between the push position and the thrust reverser position.

[0111] It appears that during the deployment and withdrawal of the obturation membrane 17 between the push position and the push reversal position, the obturation membrane 17 comes out of the cavity 31 and then goes back into it.

[0112] Due to the circulation of gas in the general direction of flow 11, the sealing membrane 17 is constrained towards the rear frame 23 and comes into contact with the external boundary wall 27, particularly in an initial part of the stroke between the thrust position and the thrust reversal position.

[0113] During this contact, the sealing membrane 17 imposes a stress with a component along the general flow direction 11 on the mobile structure 13. The stress corresponds to the cooperation between the sealing membrane 17 and the upstream end 33 of the external boundary wall 27. The upstream end 33 pushes the sealing membrane 17 in the opposite direction to the general flow direction 11. The sealing membrane 17 is thus stretched and rubs against the upstream end 33 in the manner of a belt or cable on a pulley, which pushes the mobile structure 13 downstream.

[0114] This constraint is reduced or eliminated by the restraint system 21. On at least one of the strokes of the thrust reverser, the sealing membrane 17 is in contact with the external boundary wall 27 but the applied force is less.

[0115] The retention system 21 can also, depending on the design, cause a separation over part of the stroke between the thrust position and the thrust reversal position. During this separation, no stress is imposed by the sealing membrane 17 on the moving structure 13.

[0116] The sealing membrane 17 can be made of a material known to those skilled in the art for this type of application. For example, it can be an unimpregnated fabric, such as aramid fibers. The sealing membrane can also be made of a composite material with a particularly flexible matrix, such as aliphatic polyurethane or silicone. In this case, the matrix provides low flexural strength, and the behavior of the resulting structure is indeed that of a membrane.

[0117] The sealing membrane 17 is configured to fold in a perfectly reversible manner. Preferably, this folding can correspond to an elastic extension or to fiber sliding of the sealing membrane 17.

[0118] In particular, the folding of the sealing membrane 17 has a very small radius of curvature compared to the surface of the sealing membrane 17.

[0119] The sealing membrane 17 has a very small thickness compared to its surface area. For example, the thickness is on the order of 0.1 to 3 mm. For information purposes, it is observed that the sealing membrane 17 behaves like a boat sail when it is under pressure.

[0120] The external boundary wall 27 is an acoustic panel or sliding panel of the transcowl.

[0121] Each retention system 21 includes a linking element 35 configured to cooperate with a corresponding attachment point 37 of the fixed structure 3, here in particular of the front frame 5, on the one hand and configured to cooperate with the corresponding sealing membrane 17 at an attachment point 39 on the other hand, the attachment point 39 being in the cavity 31 in the push position.

[0122] The sealing membrane 17 is thus subjected to a restoring force in the opposite direction to the general flow direction 11 by a simple mechanism for fixing the sealing membrane 17 to the front frame 5 via a connecting element 35.

[0123] The connecting element 35 is configured to be contained within a space delimited by the cavity 31 and the front frame 5 in the push position so as to be outside the secondary vein 9.

[0124] In the push position, the first end 25 is located in the cavity 31 so that the sealing membrane 17 is at least partly in contact with the external boundary wall 27 inside the cavity 31, the hook point 39 being located at a determined distance from the first end 25.

[0125] The determined distance defines an intermediate position of total detachment of the sealing membrane 17 from the external boundary wall 27, which is located between the thrust position and the thrust reversal position, the sealing membrane 17 no longer being in contact with the external boundary wall 27 from the position intermediate detachment.

[0126] In other words, between the intermediate detachment position and the thrust reversal position, the sealing membrane 17 is no longer in contact with the moving structure 13 thanks to the action of the connecting element 35 as shown in figures 4 and 7.

[0127] At the end of the opening of the mobile structure 13, the sealing membrane 17 does not disturb the movement of the mobile structure 13, which requires less effort to move the mobile structure 13 at the end of opening and at the beginning of closing.

[0128] During closure towards the thrust position, the sealing membrane 17 comes into contact with the external boundary wall 27 in the intermediate separation position. It should be noted that the forces exerted by the sealing membrane 17 on the external boundary wall 27 are, however, limited by the action of the connecting element 35, which holds the sealing membrane 17 upstream.

[0129] The determined distance defines the stage of opening of the mobile structure 13 from which the connecting element 35 is stretched and applies a restoring force on the sealing membrane 17.

[0130] The greater the determined distance, the earlier the restoring force on the sealing membrane 17 appears. One possibility is to define a force corresponding to an opening of approximately 80%. A more premature activation of the connecting element is on the order of 70% of the opening.

[0131] The energizing by the connecting element 35 does not necessarily correspond to the moment when the sealing membrane 17 ceases to be in contact with the moving structure 13. The sealing membrane 17 may be taut and still in contact with the moving structure 13 and then detach completely from the moving structure 13 with the advancement of the opening.

[0132] The connecting element 35 is dimensioned to extend in a straight line between the attachment point 39 and the fixing point 37 in the push position as illustrated in [Fig.2],

[0133] According to an embodiment shown in [Fig. 5], the connecting element 35 may have a length greater than a straight-line distance between the attachment point 39 and the fixing point 37 in the thrust position. The connecting element 35 is then relaxed in the thrust position and at the beginning of its transit towards the thrust reversal position.

[0134] The length of the connecting element 35 thus also has an influence on the stage of opening of the mobile structure 13 from which the connecting element 35 becomes tense.

[0135] The retention system 21 may optionally include an elastic retention device 41 configured to apply a restoring force to the connecting element 35 towards the attachment point as illustrated in Figures 5 to 7.

[0136] According to one possibility, illustrated in [Fig. 5], the elastic restraint device 41 is an elastic piece connecting the front frame 5 to the connecting element 35. The elastic piece can be a cord made of an elastic material fixed to the front frame 5 and the connecting element 35. This also works when the cord is fixed to another suitable location on the fixed part 3.

[0137] The elastic part is configured to expand as the mobile structure 13 opens. This gradually and then completely detaches the sealing membrane 17 from the mobile structure 13.

[0138] According to another possibility, illustrated in Figures 6 and 7, the elastic retention device 41 is a winder attached to or formed within the front frame 5. The winder includes a return spring dimensioned to allow the progressive separation of the sealing membrane 17 from the movable structure 13 during opening. As an alternative to the spring, a motor, for example an electric one, can be used as the return force.

[0139] The connecting element 35 is a cable or strap of fixed length. Alternatively, other devices could be used as long as they fulfill the function of connecting the front frame 5 and the shutter membrane 17.

[0140] The retention system 21 may also include a reinforcement element 43 configured to link the linking element 35 to the sealing membrane 17 in a reinforcement location 45 separate from the attachment point 39 as illustrated in [Fig.7].

[0141] The reinforcement location 45, distinct from the attachment point 39, allows the shape taken by the sealing membrane 17 to be defined more precisely than with only the attachment point 39.

[0142] The reinforcing element 39 is a cable or strap made of the same material as the connecting element 39 and connected to the latter.

[0143] As also seen in [Fig.8], each sealing membrane 17 comprises a second end 47 opposite to the first end 25 and connected to the internal boundary wall 7 by a corresponding connecting rod 49 or other mechanical system, the connecting rod 49 or other mechanical system being configured to move the second end 47 between a low position near or in contact with the internal boundary wall 7 in thrust reversal position and a high position near or in contact with the external boundary wall 27 in thrust position.

[0144] In the lower position, the obturation membrane 17 extends in the secondary vein 9 at least partly transversely to the general direction of flow 1 over almost all or all of the flow section, while in the upper position the obturation membrane 17 is almost or totally no longer present in the secondary vein 9 and has entered the cavity.

[0145] The other mechanical system may include an arrangement of cables and corresponding guides connecting the second end 47 to the fixed structure 3, said arrangement being configured to be set in motion by the movement of the mobile structure 13 between the push position and the push reversal position.

[0146] Each connecting rod 49 has a lower end 51 configured to be mounted on the internal boundary wall 7, preferably via a pivot or ball joint.

[0147] Each connecting rod 49 is designed to move from the upper position in which said connecting rod 49 is radially projecting into the secondary vein 9 to the lower position in which said connecting rod 49 is folded down downstream.

[0148] In the upper position, each connecting rod 49 can adopt a radial or substantially radial orientation with respect to the longitudinal central axis 15 of the thrust reverser 1, while in the lower position, each connecting rod 49 can adopt an axial or substantially axial orientation.

[0149] Each connecting rod 49 includes a return device configured to apply a force tending to tilt said connecting rod 49 towards the lower position. This ensures proper seating of the sealing diaphragm 17 during the transition to the thrust reversal position.

[0150] The connecting rods 49 are spaced circumferentially from each other within the secondary vein 9, and their number can vary for example from two to ten, depending on the angular extent of the obturation membrane 17 as can be seen in [Fig.8].

[0151] The movable structure 13 is configured to slide relative to the fixed structure 3 by means of a rail-slide system of the thrust reverser 1, the rail-slide system being configured to guide the movable structure 13 from front to back during the opening phase of the reverser to the thrust reversing position, and from back to front during the closing phase to the thrust position.

[0152] As illustrated in [Fig.9], the thrust reverser 1 includes a set of actuators 53 provided in the fixed structure 3 to move the moving structure 13 relative to the fixed structure 3.

[0153] The actuator assembly 53 is configured to be set in motion by a cylinder 55 of the thrust reverser 1 associated with a flexible shaft 57 of the thrust reverser 1. A dedicated control assembly 59 of the thrust reverser 1 controls the cylinder 55 and the actuator assembly 53.

[0154] The thrust reverser 1 comprises at least one set of deflection grids having an angular amplitude identical or similar to that of the corresponding cowling. The grid assembly is fixed and extends between the front frame and the rear frame.

[0155] It thus appears that the retention system(s) 21 make it possible to limit the displacement of the corresponding sealing membrane 17 in the general direction flow 11 and thus avoid or limit the stress of the sealing membrane 17 on the moving structure 13.

[0156] This arrangement thus facilitates the movement of the mobile structure 13 which is little disturbed by the presence of the sealing membrane 17.

[0157] Furthermore, the use of the retention system 21 makes it possible not to oversize the cylinder 55. Indeed, in the absence of the retention system 21, the sealing membrane 17 is in contact with the external delimiting wall 27 which creates resistance to the movement of the mobile structure 13, particularly at the end of opening and during the closing of the mobile structure 13.

[0158] As can be understood, the invention is not limited to the single embodiment described above by way of example, but on the contrary encompasses all variants of its realization.

Claims

Claims

1. Thrust reverser (1) for an aircraft propulsion unit, the thrust reverser (1) comprising: - a fixed structure (3) provided with a front frame (5) and an internal delimiting wall (27) of a secondary vein (9) of the propulsion unit, the secondary vein (9) being intended to be crossed by a secondary flow in a general direction of flow (11), - a mobile structure (13) provided with at least one cover (14), the mobile structure (13) being movable in translation relative to the fixed structure (3) along a longitudinal central axis (15) of the thrust reverser (1) between a thrust position and a thrust reversal position, - at least one sealing membrane (17) designed to deflect at least a portion of the secondary flow outwards through a radial opening (19) formed between the front frame (5) and the mobile structure (13) in position reverse thrust,the at least one sealing membrane (17) extending in the secondary vein (9) in the thrust reversal position, - at least one retaining system (21) designed to cooperate with the fixed structure (3) and the corresponding sealing membrane (17), said retaining system (21) being configured to subject the corresponding sealing membrane (17) to a restoring force comprising a component opposite to the general direction of flow (11) in the thrust reversal position.,

2. Thrust reverser (1) according to claim 1, wherein: - the fixed structure (3) comprises a rear frame (23), the at least one sealing membrane (17) having a first end (25) fixed on or cooperating with the rear frame (23), - each cowl (14) comprises an external delimiting wall (27) configured to delimit the secondary vein (9) with the internal delimiting wall (7) in the thrust position and an external panel (29) having an outer aerodynamic surface of the thrust reverser (1), - each cover (14) has a cavity (31) open towards the front frame (5) in the thrust position and arranged between the external delimiting wall (27) and the external panel (29), the rear frame (23) being located in the cavity (31) in the thrust position so that the at least one sealing membrane (17) is at least partly in the cavity (31) in the thrust position.

3. Thrust reverser (1) according to claim 2, wherein each retaining system (21) comprises a connecting element (35) configured to cooperate with a corresponding fixing point (37) of the fixed structure (3) on the one hand and configured to cooperate with the corresponding sealing membrane (17) at an attachment point (39) on the other hand, the attachment point (39) being in the cavity (31) in the thrust position.

4. Thrust reverser (1) according to claim 3, wherein the connecting element (35) is configured to be included in a space delimited by the cavity (31) and the front frame (5) in the thrust position so as to be outside the secondary vein (9).

5. Thrust reverser (1) according to one of claims 3 or 4, wherein, in the thrust position, the first end (25) is located in the cavity (31) so that the sealing membrane (17) is at least partly in contact with the external delimiting wall (27) inside the cavity (31), the attachment point (39) being located at a determined distance from the first end (25), the determined distance defining an intermediate position of total detachment of the sealing membrane (17) from the external delimiting wall (27) which is located between the thrust position and the thrust reversal position, the sealing membrane (17) no longer being in contact with the external delimiting wall (27) from the intermediate detachment position.

6. Thrust reverser (1) according to one of claims 3 to 5, wherein the connecting element (35) is dimensioned to extend rectilinearly between the attachment point (39) and the fixing point (37) in the thrust position.

7. Thrust reverser (1) according to one of claims 3 to 6, wherein the retaining system (21) further comprises an elastic retaining device (41) configured to subject a restoring force to the connecting element (35) towards the attachment point (37).

8. Thrust reverser (1) according to one of claims 3 to 7, wherein the retaining system (21) also comprises a reinforcing element (43) configured to connect the connecting element (35) to the sealing membrane (17) at a reinforcing location (43) separate from the attachment point (39).

9. Thrust reverser (1) according to one of claims 1 to 8, wherein each sealing membrane (17) comprises a second end (47) opposite the first end (25) and connected to the internal delimiting wall (7) by a corresponding connecting rod (49) or another mechanical system, the connecting rod (49) or the other mechanical system being configured to move the second end (47) between a low position near or in contact with the internal delimiting wall (7) in the thrust reversal position and a high position near or in contact with the external delimiting wall (27) in the thrust position.

10. Thrust reverser (1) according to one of claims 1 to 9, wherein the movable structure (13) is configured to slide relative to the fixed structure (3) by means of a rail-slide system of the thrust reverser (1), the rail-slide system being configured to guide the movable structure (13) from front to rear during the opening phase of the reverser to the thrust reversal position, and from rear to front during the closing phase to the thrust position, the thrust reverser (1) comprising a set of actuators (53) arranged in the fixed structure (3) to move the movable structure (13) relative to the fixed structure (3).

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