A turbofan engine including a system for blocking a bypass flow path having a yarn membrane

Abstract

The invention relates to a turbofan engine (100) having a nacelle (102) and a flow path (204), wherein the nacelle comprises: a movable cowling (216) enabling to define a window (220) between the flow path and the outside; a gauze membrane (252) having a first edge fixed to the movable cowling and alternatively assuming a folded position or an unfolded position spanning the flow path (204); and a pneumatic system (350) displacing a second edge of the gauze membrane from the folded position to the unfolded position and vice versa. The pneumatic system (350) comprises: a rigid main roller (352); for each gauze membrane (252) at least one extensible secondary roller (354) fixed to the second edge of said gauze membrane (252); and a pressurization and depressurization system alternatively generating a pressure or a depression in each secondary roller (354). Replacing the reverse door and its drive mechanism with a flexible gauze membrane and a pneumatic system allows to reduce the weight.

Description

TECHNICAL FIELD

[0001] The invention relates to a turbofan engine comprising a flexible gauze membrane and a pneumatic deployment system which deploys the gauze membrane to obstruct the flow path of the bypass flow and which folds the gauze membrane to open the flow path of the bypass flow, and to an aircraft comprising at least one such turbofan engine. BACKGROUND

[0002] The aircraft comprises a fuselage to which a wing is fixed on each side. At least one turbofan engine is suspended under each wing. Each turbofan engine is fixed under the wing via a pylon which is fixed between the structure of the wing and the structure of the turbofan engine.

[0003] The turbofan engine comprises an engine and a nacelle fixed around the engine. The turbofan engine has a bypass flow path between the nacelle and the engine in which the bypass flow circulates.

[0004] The nacelle comprises a plurality of reverse doors each of which is rotatably mobile on the structure of the nacelle between a retracted position in which it is outside the bypass flow path and a deployed position in which it is positioned across the bypass flow path to deflect the bypass flow to a window which is open in a wall of the nacelle and between the bypass flow path and the outside of the nacelle.

[0005] The bypass flow is thus deflected outwards, more particularly towards the front of the turbofan engine to generate a reverse thrust.

[0006] Although the reverse doors are perfectly satisfactory, it is desirable to find a different mechanism, in particular a lighter one. SUMMARY

[0007] One aim of the invention is to propose a turbofan engine comprising a flexible gauze membrane and a pneumatic system which deploys the gauze membrane to obstruct the flow path of the secondary flow and which folds the gauze membrane to open the flow path of the secondary flow.

[0008] To this end, a turbofan engine is proposed which has a longitudinal direction and comprises an engine and a nacelle around the engine, comprising a fan casing in which the flow path of the secondary flow is delimited between the nacelle and the engine, and in which an air flow circulates from the front to the rear of the turbofan engine, said nacelle comprising:

[0009] - a fixed structure fixed to the fan casing;

[0010] - a movable cowl translatable in translation on the fixed structure between an advanced position, in which it is positioned close to the fan casing, and a retracted position, in which it is positioned away from the fan casing, thus defining between them an open window between the flow path and the outside of the nacelle;

[0011] - a set of actuators which ensure the displacement of the movable cowl between the advanced position and the retracted position and vice versa;

[0012] - a plurality of flexible gauze membranes having a first edge fixed to the movable cowl and a second edge opposite the first edge, wherein said gauze membranes can alternatively assume a folded position, in which they are housed in the movable cowl, or an unfolded position, in which they extend across the flow path between the first edge and the engine; and

[0013] - a pneumatic system arranged to displace the second edge of each gauze membrane to displace said gauze membrane from the folded position to the unfolded position and to displace the second edge of each gauze membrane to displace said gauze membrane from the unfolded position to the folded position, wherein the pneumatic system comprises:

[0014] - a rigid main roller fixed inside the movable cowl behind the window;

[0015] - for each gauze membrane at least one extendable secondary roller fixed to the main roller and wherein the inside of each secondary roller is fluidly continuous with the inside of the main roller, wherein the second edge of said gauze membrane is fixed to each secondary roller; and

[0016] - a pressurization and depressurization system which alternately generates a pressure in the main roller and consequently in each secondary roller to charge them in the transition from the advanced position to the retracted position or generates a depression in the main roller and consequently in each secondary roller to discharge them in the transition from the retracted position to the advanced position.

[0017] The replacement of the reverse door and its drive mechanism with the flexible gauze membranes and the pneumatic system allows to reduce the weight.

[0018] Advantageously, the pressurization and depressurization system comprises:

[0019] - a Venturi effect tube having an inlet section, an outlet section and an intermediate section between the inlet section and the outlet section, wherein the inlet section is fluidly connected to an air extraction point in the flow path;

[0020] - a bypass line, the inlet of which is fluidly connected to the inlet section and the outlet of which is fluidly connected to the intermediate section;

[0021] - a terminal line, the inlet of which is fluidly connected to the bypass line and the outlet of which is fluidly connected to the main roller;

[0022] - a first valve, provided at the inlet of the bypass line, which can alternatively assume an open position, allowing passage between the inlet section and the bypass line, or a closed position, preventing passage between the inlet section and the bypass line;

[0023] - a second valve, provided at the inlet of the terminal line, which can alternatively assume a first position, allowing passage between the bypass line and the terminal line from the inlet of the bypass line and preventing passage between the terminal line and the bypass line to the outlet of the bypass line, and a second position, allowing passage between the terminal line and the bypass line to the outlet of the bypass line and preventing passage between the bypass line and the terminal line from the inlet of the bypass line; and

[0024] - a third valve, provided at the outlet of the bypass line, which can alternatively assume an open position, allowing passage between the bypass line and the outlet section, or a closed position, preventing passage between the bypass line and the outlet section.

[0025] Advantageously, the turbofan engine comprises:

[0026] - for each veil, a roller mounted to rotate freely behind the window of the movable fairing when the movable fairing is in the retracted position, wherein a first edge of the veil is fixed to the roller, wherein, in the folded position, the veil is wound around the roller, or in the unfolded position, the veil is unwound from the roller;

[0027] - an unfolding mechanism arranged to displace a second edge of each veil to displace the veil from the folded position to the unfolded position; and

[0028] - a folding mechanism arranged to drive rotation of each roller to displace the veil associated with the roller from the unfolded position to the folded position.

[0029] Advantageously, the unfolding mechanism comprises:

[0030] - for each second edge, a plate fixed to the second edge;

[0031] - for each plate, at least one pulling pulley mounted to rotate freely on the plate;

[0032] - a cable which passes through each of the traction pulleys; and

[0033] - for each end of the cable, a disengageable displacement system which ensures traction of the end.

[0034] Advantageously, there is a traction pulley at each end of the plate.

[0035] Advantageously, each displacement system comprises a set of guide pulleys and an electric winder on which the cable is wound.

[0036] According to a particular embodiment, for each roller, the folding mechanism comprises: a deflection pulley coaxially fixed to the roller; a winding pulley fixed to the fixed structure; a winding cable, one end of which is fixed to the fixed structure and the other end of which is fixed to the winding pulley, and wherein the winding cable passes through the deflection pulley; a nitrogen damper, the cylinder of which is fixed to the fixed structure and the piston of which slides in the cylinder; and a conversion system which ensures the conversion of the rotational movement of the winding pulley into the translational movement of the piston and vice versa.

[0037] According to a particular embodiment, for each roller, the folding mechanism comprises: a deflection pulley coaxially fixed to the roller; a winding pulley; a winding cable, one end of which is fixed to the fixed structure and the other end of which is fixed to the winding pulley, and wherein the winding cable passes through the deflection pulley; and a disengageable electric winder to which the winding pulley is fixed.

[0038] The application also proposes an aircraft comprising at least one turbofan engine according to any one of the above variants. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above features of the application will become more apparent from reading the following description of exemplary embodiments given with reference to the attached drawings among which:

[0040] Figure 1 is a side view of an aircraft comprising a turbofan engine according to the application;

[0041] Figure 2 is a perspective view of a turbofan engine according to the application in the deployed position of the veil;

[0042] Figure 3 is a schematic view of a turbofan engine according to the application seen in cross-section through a radial plane, in the advanced and folded position;

[0043] Figure 4is a schematic view of a turbofan engine according to the application, seen in cross section through a radial plane, in the retracted and deployed position;

[0044] Figure 5 is a schematic view of a pressurization and depressurization system in the pressurized position, implemented in the context of the application;

[0045] Figure 6 is the pressurization and depressurization system of Figure 5 in the pressure maintenance position;

[0046] Figure 7 is the pressurization and depressurization system of Figure 5 in the depressurized position;

[0047] Figure 8 is a schematic front view of a deployment mechanism in the folded position;

[0048] Figure 9 is a schematic front view of a deployment mechanism in the deployed position; and

[0049] Figure 10 is a perspective view of a folding mechanism. DETAILED DESCRIPTION

[0050] In the following description, the terms relating to position are taken in relation to the forward direction of the aircraft, indicated by arrow F in Figure 1 .

[0051] Figure 1 is shown an aircraft 10 comprising a fuselage 12, on each side of which is fixed a wing 14 carrying at least one turbofan engine 100 according to the application. The turbofan engine 100 is fixed under the wing 14 via a pylon 16.

[0052] Figure 3 and Figure 4 is shown a turbofan engine 100 having a nacelle 102 and an engine 20 housed inside the nacelle 102. The turbofan engine 100 also comprises a fan casing 202.

[0053] In the following description, and as is customary, X denotes the longitudinal direction of the turbofan engine 100, which is parallel to the longitudinal axis of the aircraft 10 and is oriented positively towards the front of the aircraft 10; Y denotes the transverse direction, which is horizontal when the aircraft is on the ground; Z denotes the vertical direction, the three directions X, Y and Z being mutually orthogonal.

[0054] The turbofan engine 100 has a flow path 204 between the nacelle 102 and the engine 20, through which the bypass flow 208 from the air intake circulates through the fan 300 and which therefore flows in a flow direction from the front to the rear of the turbofan engine 100.

[0055] The nacelle 102 has a fixed structure 206 fixedly mounted on the fan casing 202. The fixed structure 206 comprises here in particular a front frame 210 mounted around the fan casing 202 and an outer panel 212 fixed to the front frame 210 and forming an outer aerodynamic surface.

[0056] The nacelle 102 has a movable assembly 214 having a movable fairing 216 which here forms an outer wall of a jet nozzle.

[0057] The nacelle 102 also has a cascade 221 fixed to the movable assembly 214.

[0058] The movable fairing 216 is mounted in translational movement on the fixed structure 206 of the nacelle 102 in a translation direction generally parallel to the longitudinal direction X.

[0059] The movable fairing 216 is movable between an advanced position ( Figure 3 ) and a retracted position ( Figure 4 ), and vice versa. In the advanced position, the movable fairing 216 is positioned as far forward as possible relative to the direction of advancement, so that it is close to the outer panel 212 and the fan casing 202 and thus forms a continuous aerodynamic surface. In the retracted position, the movable fairing 216 is positioned as far rearward as possible relative to the direction of advancement, so that it is far from the outer panel 212 and the fan casing 202, thereby defining a window 220 between them which is open between the flow path 204 and the outside, and the cascade 221 is positioned in this window 220.

[0060] In the advanced position, the movable fairing 216 and the outer panel 212 extend into one another to define an outer surface of the nacelle 102, and the movable fairing 216 and the fan casing 202 extend into one another to define an outer surface of the flow path 204. In the advanced position, the cascade 221 is housed between the outer panel 212 and the fan casing 202.

[0061] In the retracted position, the movable fairing 216 is at a distance from the fan casing 202 and the outer panel 212 and defines an open window 220 between them between the flow path 204 and the outside of the nacelle 102. That is to say, the air of the bypass flow 208 passes through the cascade 221 to pass through the window 220 to return to the outside of the turbofan engine 100.

[0062] The translation of the movable fairing 216 is performed by any suitable means, such as a slide system between the beams of the fixed structure 206 and the movable fairing 216.

[0063] The nacelle 102 also comprises a set of actuators (not shown) which ensure the translational displacement of the movable fairing 216 between the advanced position and the retracted position, and vice versa. Each actuator is controlled by a control unit, for example of the processor type, which controls the displacement in one direction or the other according to the needs of the aircraft 10.

[0064] For example, each actuator can take the form of a double-acting cylinder (two directions of operation) whose cylinder is fixed to the fixed structure 206 and whose rod is fixed to the movable fairing 216.

[0065] The fan casing 202 and the outer panel 212 delimit the window 220 upstream with respect to the flow direction, and the movable fairing 216 delimits the window 220 downstream with respect to the flow direction.

[0066] Figure 2 The movable fairing 216 and the engine 20 are shown, which is represented here by a cylinder in dotted and dashed line.

[0067] The nacelle 102 comprises a plurality of gauze membranes 252, each of which is flexible and takes here the general form of a trapezoid. Each gauze membrane 252 can alternatively take a folded position ( Figure 3 ) or an unfolded position ( Figure 2 and 4 ). Each gauze membrane 252 has a fixed first edge and a movable second edge opposite the first edge. When the movable fairing 216 is in the retracted position, each first edge is fixed to the movable fairing 216, inside the movable fairing 216, outside the flow path 204 and behind the window 220.

[0068] In the folded position, each gauze membrane 252 is housed in the movable fairing 216, while in the unfolded position, the gauze membrane 252 extends between the first edge and the second edge, which extends across the flow path 204 and close to the engine 20, so as to obstruct this flow path 204. Thus, the second edge is distant from the first edge in the unfolded position and close to the first edge in the folded position.

[0069] Here, each first edge is embedded in a plane at right angles to the longitudinal direction X and at right angles to a radial direction with respect to the longitudinal direction X and passing through the middle of the first edge.

[0070] The nacelle 102 also comprises a pneumatic system 350 arranged to displace the second edge of each veil 252 to displace said veil 252 from the folded position to the unfolded position and to displace the second edge of each veil 252 to displace said veil 252 from the unfolded position to the folded position.

[0071] The pneumatic system 350 is synchronized with the displacement of the movable cowl 216 for the transition from the folded position to the unfolded position to correspond to the transition from the advanced position to the retracted position and for the transition from the unfolded position to the folded position to correspond to the transition from the retracted position to the advanced position.

[0072] In the unfolded position, the veils 252 are positioned behind the window 220 to form a barrier in the flow path 204, deflecting the bypass flow 208 from the front towards the window 220. In the unfolded position, the second edge of each veil 252 is around the engine 20.

[0073] The operation therefore comprises, from the advanced / folded position, commanding activation of the actuator to displace the movable cowl 216 from the advanced position to the retracted position, which drives the displacement of the cascade 221 facing the window 220.

[0074] During this displacement, the pneumatic system 350 unfolds each veil 252 across the flow path 204.

[0075] Conversely, the operation comprises, from the retracted / unfolded position, commanding activation of the actuator to displace the movable cowl 216 from the retracted position to the advanced position, which drives the displacement of the cascade 221 to its initial position.

[0076] During this displacement, the pneumatic system 350 folds each veil 252 onto the outside of the flow path 204.

[0077] The use of a plurality of flexible veils 252 allows a reduction in the weight of the assembly compared with the use of a reverse door of the prior art. Furthermore, the veils 252 make it possible to adjust the efficiency and the aeramatch, which are features of the thrust reverser. The term "aeramatch" denotes here the ratio between the nozzle outlet section in direct jet mode and the jet nozzle outlet section in thrust reversal mode.

[0078] The pneumatic system 350 comprises a main roller 352 fixed at the rear of the inner window 220 of the mobile fairing 216 and generally in the form of an annular face around the longitudinal direction X, at least one secondary roller 354 for each veil 252 fixed to the main roller 352 and in which the interior of each secondary roller 354 is fluidly continuous with the interior of the main roller 352. The material constituting the main roller 352 is rigid, for example metal, while the material constituting the secondary rollers 354 is highly extensible, for example made of rubber.

[0079] For example, each secondary roller 354 takes the form of a tube whose first end is fixed to the main roller 352 and whose second end is open and plugged. For example, each secondary roller 354 takes the form of a tube whose two ends are fixed to the main roller 352, thus forming a ring.

[0080] For each secondary roller 354 associated with a veil 252, the second edge of the veil 252 is fixed to each secondary roller 354, either at the open second end or in the middle of the tube depending on the type of secondary roller 354. In any case, the second edge is fixed to the secondary roller 354 so that, when the secondary roller 354 is pressurized, the second edge is positioned around the engine 20. The more the number of secondary rollers 354 for a veil 252, the greater the tensioning of the second edge in the deployed position.

[0081] The pneumatic system 350 comprises a pressurization and depressurization system which alternately generates a pressure in the main roller 352 and therefore in each secondary roller 354 to pressurize them, or a depression in the main roller 352 and therefore in each secondary roller 354 to depressurize them. The pressurization and depressurization system is controlled by the control unit as required.

[0082] Thus, in transition from the advanced / folded position to the retracted / deployed position, the control unit controls the pressurization and depressurization system to generate a pressure and pressurize the secondary rollers 354, which therefore deploy the veil 252, and, in transition from the retracted / deployed position to the advanced / folded position, the control unit controls the pressurization and depressurization system to generate a depression and depressurize the secondary rollers 354, which therefore fold back the veil 252.

[0083] For example, the pressurization and depressurization system can be a fan controlled by the control unit and can alternately generate a pressure or a depression in the main roller 352.

[0084] Figures 5 to 7A particular pressurization and depressurization system 550 is shown. The particular pressurization and depressurization system 550 comprises a Venturi effect tube 552 having an inlet section 554, an outlet section 556 and an intermediate section 558 between the inlet section 554 and the outlet section 556, wherein the diameter of the intermediate section 558 is smaller than the diameter of the inlet section 554 and of the outlet section 556.

[0085] The inlet section 554 is fluidly connected to a point for taking away hot air from the flow path 204, while the outlet section 556 is fluidly connected, for example, to a heating system of the cabin of the aircraft 10.

[0086] The particular pressurization and depressurization system 550 further comprises a bypass line 560, the inlet of which is fluidly connected to the inlet section 554, while the outlet of which is fluidly connected to the intermediate section 558.

[0087] The particular pressurization and depressurization system 550 further comprises a terminal line 562, the inlet of which is fluidly connected to the bypass line 560, while the outlet of which is fluidly connected to the main roller 352.

[0088] The particular pressurization and depressurization system 550 further comprises:

[0089] - a first valve 564, which is arranged at the inlet of the bypass line 560 and which can alternatively assume an open position to allow the passage between the inlet section 554 and the bypass line 560, or a closed position to prevent the passage between the inlet section 554 and the bypass line 560;

[0090] - a second valve 566, which is arranged at the inlet of the terminal line 562 and which can alternatively assume a first position to allow the passage between the bypass line 560 and the terminal line 562 from the inlet of the bypass line 560, and to prevent the passage between the terminal line 562 and the bypass line 560 to the outlet of the bypass line 560, and a second position to allow the passage between the terminal line 562 and the bypass line 560 to the outlet of the bypass line 560, and to prevent the passage between the bypass line 560 and the terminal line 562 from the inlet of the bypass line 560; and

[0091] - a third valve 568, which is arranged at the outlet of the bypass line 560 and which can alternatively assume an open position to allow the passage between the bypass line 560 and the outlet section 556, or a closed position to prevent the passage between the bypass line 560 and the outlet section 556.

[0092] Each valve 564, 566, 568 is positioned by a control unit.

[0093] Figure 5 Corresponds to the pressurization of the secondary rollers 354. The first valve 564 is in the open position, the second valve 566 is in the first position, and the third valve 568 is in the closed position. The air from the flow path 204 is thus introduced into the primary roller 352 and each secondary roller 354 to pressurize them and bring each veil 252 into the deployed position.

[0094] Figure 6 Corresponds to the pressurization of the secondary rollers 354. The first valve 564 is in the open position, the second valve 566 is in the first position, and the third valve 568 is in the closed position. The air in the primary roller 352 and each secondary roller 354 is thus blocked.

[0095] Figure 7 Corresponds to the depressurization of the secondary rollers 354. The first valve 564 is in the closed position, the second valve 566 is in the second position, and the third valve 568 is in the open position. The air in the primary roller 352 and each secondary roller 354 is sucked into the intermediate section 556 by the Venturi effect and each secondary roller 354 is depressurized, returning each veil 252 to the folded position.

[0096] In the embodiment of Figs. 1 to 5, each veil 252 is fixed to the movable fairing 216 by a roller 254. The roller 254 is mounted so as to rotate freely on the movable fairing 216. The roller 254 is mounted inside the movable fairing 216, outside the flow path 204, and behind the window 220 when the movable fairing 216 is in the retracted position. The roller 254 is distributed angularly around the longitudinal direction X along the periphery of the movable fairing 216. Figure 8 and 9 In the embodiment of Figs. 1 to 5, each veil 252 is fixed to the movable fairing 216 by a roller 254. The roller 254 is mounted so as to rotate freely on the movable fairing 216. The roller 254 is mounted inside the movable fairing 216, outside the flow path 204, and behind the window 220 when the movable fairing 216 is in the retracted position. The roller 254 is distributed angularly around the longitudinal direction X along the periphery of the movable fairing 216.

[0097] The short body 102 thus comprises a roller 254 mounted so as to rotate freely on the movable fairing 216 for each veil 252. Each roller 254 is mounted inside the movable fairing 216, outside the flow path 204, and behind the window 220 when the movable fairing 216 is in the retracted position. The rollers 254 are distributed angularly around the longitudinal direction X along the periphery of the movable fairing 216.

[0098] In the folded position, each veil 252 is wound around the associated roller 254. Thus, in the folded position, the veil 252 is wound around the roller 254, in the deployed position, the veil 252 unwinds from the roller 254 and extends across the flow path 204 between the roller 254 and the engine 20 to obstruct the flow path 204. Thus, the first edge of each veil 252 is fixed to the associated roller 254, while the second edge is remote from the roller 254 in the deployed position and close to the roller 254 in the folded position.

[0099] Here, the axis of rotation of each roller 254 is embedded in a plane that is at right angles to the longitudinal direction X and at right angles to a radial direction with respect to the longitudinal direction X and passing through the middle of the roller 254.

[0100] The nacelle 102 further comprises an unfolding mechanism arranged to displace the second edge of each veil 252 to displace said veil 252 from the folded position to the unfolded position, and a folding mechanism arranged to drive the rotation of each roller 254 to displace the veil 252 associated with said roller 254 from the unfolded position to the folded position.

[0101] As mentioned previously, the unfolding and folding mechanisms are synchronized with the displacement of the movable fairing 216 for the transition from the folded position to the unfolded position to correspond to the transition from the advanced position to the retracted position, and for the transition from the unfolded position to the folded position to correspond to the transition from the retracted position to the advanced position.

[0102] During the displacement from the advanced / folded position to the retracted / unfolded position, the unfolding mechanism assists in the unfolding of each veil 252 across the flow path 204.

[0103] Conversely, during the displacement from the retracted / unfolded position to the advanced / folded position, the folding mechanism folds each veil 252 on the outside of the flow path 204.

[0104] Figure 8 And 9 An unfolding mechanism 500 according to a particular embodiment is shown. In these Figure 8 And 9 In the figures, for ease of understanding, only three veils 252 are shown, but the other veils 252 are angularly arranged around the longitudinal direction X.

[0105] For each veil 252, the unfolding mechanism 500 comprises a plate 502 fixed to the second edge of said veil 252, which ensures the rigidity of said second edge. Each secondary roller 354 associated with said veil 252 can be fixed to this plate 502.

[0106] Each plate 502 carries at least one pull belt wheel 504 mounted to rotate freely on said plate 502. Here, for reasons of balance, the plate 502 carries a pull belt wheel 504 at each end of said plate 502, that is to say at each end of the second edge.

[0107] For several veils 252, the unfolding mechanism 500 further comprises a cable 506 that passes through each pull belt wheel 504 of said several veils 252. In Figure 8 And 9In the embodiment of the application presented in the figures, there are two cables 506, one for the port screen 252 (not shown) and one for the starboard screen 252. Obviously, different distributions are possible.

[0108] For each end 506 of the cable, the unwinding mechanism 500 comprises a displacement system 508 which ensures the pulling of said end. Thus, the pulling of each end of the cable 506 will tighten said cable 506 and unwind each screen 252 by the displacement of the associated plate 502 under the action of the cable 506.

[0109] Each displacement system 508 here comprises a set of guide pulleys 510 and an electric reel 512 on which the cable 506 is wound.

[0110] The folding mechanism comprises a mechanism which ensures the rotation of each roller 254 in the direction in which the screen 252 is wound on the roller 254.

[0111] When the folding mechanism is activated, the unwinding mechanism must be disengaged so as not to generate any force to hold the screen 252. In Figure 8 and 9 case, each displacement system 508, and in particular each electric reel 512, must be disengaged to be able to rotate freely.

[0112] Figure 10 A folding mechanism 700 according to a particular embodiment is shown.

[0113] For each roller 254, the folding mechanism 700 comprises a deflection pulley 520 fixed coaxially to the roller 254, a winding pulley 702 fixed to the fixed structure 206 and a winding cable 522, one end of which is fixed to the fixed structure 206 and the other end of which is fixed to the winding pulley 702, and in which the winding cable 522 passes through the deflection pulley 520.

[0114] For each roller 254, the folding mechanism 700 comprises a nitrogen damper 704 comprising a cylinder 706 fixed to the fixed structure 206 and a piston 708 sliding in the cylinder 706.

[0115] For each roller 254, the folding mechanism 700 also comprises a conversion system 710 which ensures the conversion of the rotational movement of the winding pulley 702 into a translational movement of the piston 708 and vice versa.

[0116] The conversion system 710 here takes the form of a rack and pinion system.

[0117] From the advanced position, the movable assembly 214 is retracted, which tends to displace the deflection pulley 520 rearward and thus tends to unwind the winding cable 522 from the winding pulley 702.

[0118] By the action of the conversion system 710, the rotation of the winding pulley 522 causes the piston 708 to be driven into the cylinder 706 and thus causes the compression of the nitrogen gas present in the nitrogen damper 704.

[0119] Conversely, from the retracted position, when the movable assembly 214 is advanced, the winding cable 522 slackens and the pressure of the nitrogen gas on the piston 708 pushes the latter back and, by the action of the conversion system 710, the translation displacement of the piston 708 drives the rotation of the winding pulley 702 which winds the winding cable 522 and thus drives the rotation of the deflection pulley 520 which in turn drives the roller 254 and thus the winding of the veil 252.

[0120] According to another embodiment, the folding mechanism can comprise a detachable electric winder to which the winding pulley 702 is fixed and thus replaces the nitrogen damper 704 and the conversion system 710. Thus, for each roller 254, the folding mechanism comprises: a deflection pulley 520 fixed coaxially to the roller 254; a winding pulley 702; a winding cable 522, one end of which is fixed to the fixed structure 206 and the other end of which is fixed to the winding pulley 702, and wherein the winding cable 522 passes through the deflection pulley 520; and a detachable electric winder to which the winding pulley 702 is fixed. The detachment of the electric winder allows the deployment of the veil 252 when the deployment mechanism 500 is actuated.

[0121] The control unit is connected to the various elements to activate them according to the requirements. For example, the control unit controls the rotation of each electric winder and of each actuator which displaces the movable fairing 216 in one direction or the other.

[0122] Each veil 252 must have sufficient structural properties to withstand the forces generated by the bypass flow 208 and have sufficient flexibility to be able to fold. According to a particular embodiment, each veil 252 consists of a flexible mesh structure on which a flexible surface layer such as a fabric is fixed.

[0123] The application has been described more particularly for the case of an underwing nacelle, but it can be applied to a nacelle located at the rear of the fuselage.

Claims

1. A turbofan engine (100) having a longitudinal direction (X) and including an engine (20) and a nacelle (102) surrounding the engine (20), the turbofan engine including a fan housing (202) in which a flow path (204) of a bypass flow (208) is defined between the nacelle (102) and the engine (20), and wherein, Airflow circulates from the front to the rear of the turbofan engine (100), and the nacelle (102) includes: - A fixing structure (206) is fixed to the fan housing (202); - A movable fairing (216) that can translate in a translational direction on the fixed structure (206) between a forward position and a retracted position, wherein in the forward position the movable fairing (216) is positioned close to the fan housing (202) and in the retracted position the movable fairing (216) is positioned away from the fan housing (202), thereby defining an open window (220) between the flow path (204) and the outside of the nacelle (102); - A group of actuators that ensure the displacement of the movable fairing (216) between the forward position and the retracted position, and vice versa; - Multiple flexible yarn membranes (252), the multiple flexible yarn membranes having a first edge fixed to the movable fairing (216) and a second edge opposite to the first edge, wherein the yarn membranes (252) are alternately folded or unfolded, in the folded position being housed within the movable fairing (216), and in the unfolded position extending across the flow path (204) between the first edge and the engine (20); and - A pneumatic system (350) arranged to shift the second edge of each yarn film (252) to move the yarn film (252) from the folded position to the unfolded position, and to shift the second edge of each yarn film (252) to move the yarn film (252) from the unfolded position to the folded position, wherein the pneumatic system (350) includes: - Rigid main roller (352), which is fixed inside the movable fairing (216) and behind the window (220); - At least one extendable sub-roller (354) for each yarn film (252), said sub-roller being fixed to said main roller (352), wherein the interior of each sub-roller (354) is fluidly continuous with the interior of said main roller (352), wherein the second edge of said yarn film (252) is fixed to each said sub-roller (354); and - A pressurization and depressurization system (550) alternately generates pressure in the main roller (352) and thus in each auxiliary roller (354) to pressurize them during the transition from the forward position to the retracted position, or generates depressurization in the main roller (352) and thus in each auxiliary roller (354) to depressurize them during the transition from the retracted position to the forward position.

2. The turbofan engine (100) according to claim 1, characterized in that, The pressurization and depressurization system (550) includes: - A Venturi effect tube (552) having an inlet section (554), an outlet section (556) and an intermediate section (558) between the inlet section (554) and the outlet section (556), wherein the inlet section (554) is fluidly connected to an air extraction point in the flow path (204); - Bypass line (560), the inlet fluid of the bypass line is connected to the inlet section (554), and the outlet fluid of the bypass line is connected to the intermediate section (558); - Terminal line (562), the inlet fluid of which is connected to the bypass line (560), and the outlet fluid of which is connected to the main roller (352); - A first valve (564) is disposed at the inlet of the bypass line (560) and is capable of alternating between an open position and a closed position, wherein the open position allows passage between the inlet section (554) and the bypass line (560) and the closed position prevents passage between the inlet section (554) and the bypass line (560); - A second valve (566), disposed at the inlet of the terminal line (562), and capable of alternately presenting a first position and a second position, the first position allowing passage from the inlet of the bypass line (560) between the bypass line (560) and the terminal line (562) and blocking passage from the terminal line (562) to the outlet of the bypass line (560), the second position allowing passage from the terminal line (562) and the bypass line (560) to the outlet of the bypass line (560) and blocking passage from the inlet of the bypass line (560) to the terminal line (562); and - A third valve (568) is disposed at the outlet of the bypass line (560) and is capable of alternating between an open position and a closed position. The open position allows passage between the bypass line (560) and the outlet section (556), while the closed position prevents passage between the bypass line (560) and the outlet section (556).

3. The turbofan engine (100) according to claim 1, characterized in that, The turbofan engine includes: - For each yarn film (252), the roller (254) is mounted to rotate freely behind the window (220) on the movable shroud (216) when the movable shroud (216) is in the retracted position, wherein the first edge of the yarn film (252) is fixed to the roller (254), wherein in the folded position, the yarn film (252) is wound around the roller (254), or in the unfolded position, the yarn film (252) is unwound from the roller (254); - An unfolding mechanism (500) arranged to shift the second edge of each yarn film (252) to move the yarn film (252) from the folded position to the unfolded position; and - A folding mechanism (700) arranged to drive each roller (254) to rotate to displace the yarn film (252) associated with the roller (254) from the unfolded position to the folded position.

4. The turbofan engine (100) according to claim 3, characterized in that, The deployment mechanism (500) includes: - For each second edge, the plate (502) is fixed to the second edge; - At least one pulley (504) for each plate (502), said at least one pulley is mounted to rotate freely on said plate (502); - Cable (506), said cable passing through each pulley (504); and - A disengageable displacement system (508) for each end of the cable (506) ensures the pull on the end.

5. The turbofan engine (100) according to claim 4, characterized in that, At each end of the plate (502) there is a pulley (504).

6. The turbofan engine (100) according to claim 4, characterized in that, Each shifting system (508) includes a group of guide pulleys (510) and an electric winder (512) on which the cable (506) is wound.

7. The turbofan engine (100) according to claim 4, characterized in that, For each roller (254), the folding mechanism (700) includes: a deflection pulley (520) coaxially fixed to the roller (254); a winding pulley (702) fixed to the fixed structure (206); a winding cable (522) with one end fixed to the fixed structure (206) and the other end fixed to the winding pulley (702), wherein the winding cable passes through the deflection pulley (520); a nitrogen damper (704) with a cylinder (706) fixed to the fixed structure (206) and a piston (708) sliding in the cylinder (706); and a conversion system (710) that ensures that the rotational motion of the winding pulley (702) is converted into the translational motion of the piston (708) and vice versa.

8. The turbofan engine (100) according to claim 4, characterized in that, For each roller (254), the folding mechanism includes: a deflecting pulley (520) coaxially fixed to the roller (254); a winding pulley (702); a winding cable (522), one end of which is fixed to the fixing structure (206) and the other end of which is fixed to the winding pulley (702), wherein the winding cable (522) passes through the deflecting pulley (520); and a detachable electric winder, to which the winding pulley (702) is fixed.

9. An aircraft (10) comprising at least one turbofan engine (100) according to claim 1.

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