FR3027066A1 - THRUST INVERTER FOR AN AIRCRAFT AIRCRAFT TANK AND NACELLE - Google Patents

Abstract

The present invention relates to a thrust reverser for an aircraft turbojet engine nacelle, and in particular to a thrust reverser (1) for a nacelle (2) of a turbojet engine (20) comprising at least one movable cowl (3) mounted on a fixed structure (4) of the inverter (1) between a closed position, in which it ensures the aerodynamic continuity of the nacelle (2) and deactivates means for deflecting at least a portion of the air flow, and an opening position in which it opens a passage in the nacelle and activates said deflection means, each movable cowl (3) being able to be moved between these two positions by actuators (5), the thrust reverser ( 1) being characterized in that it comprises at least one failure detection device (6) comprising a retractable stop (7), controlled by at least one activation means (8), said stop being retractable between: a position retracted, when the hood mobil e (3) performs a normal stroke, in which the stop (7) is deactivated; and an extended detecting position, in case of predetermined over-travel of the movable cowl (3) in which the stop (7) is activated and forms an obstacle to closing the movable cowl (3) with respect to the fixed structure (4). ), said over-travel being detected by the activation means (8).

Description

The present invention relates to a thrust reverser for an aircraft turbojet engine nacelle comprising a detection device in the event of failure of at least one actuator and to a nacelle comprising at least one such thrust reverser.

An airplane is driven by several turbojets each housed in a nacelle for channeling the air flows generated by the turbojet engine which also houses a set of actuators providing various functions when the turbojet engine is in operation or stopped. These actuators may include, in particular, a mechanical thrust reversal system. A nacelle generally has a tubular structure comprising an air inlet upstream of the turbojet engine, a median section intended to surround a fan of the turbojet engine, a downstream section housing a thrust reverser means and intended to surround the combustion chamber of the turbojet engine. and is generally terminated by an ejection nozzle whose outlet is located downstream of the turbojet engine. Modern nacelles are intended to house a turbofan engine capable of generating, via the blades of the fan, an air flow part of which, called a hot or primary flow, circulates in the combustion chamber of the turbojet engine, and the other part, called cold or secondary flow, circulates outside the turbojet through an annular passage, also called vein, formed between a shroud of the turbojet engine and an inner wall of the nacelle. The two air flows are ejected from the turbojet engine from the rear of the nacelle. The role of a thrust reverser is, during the landing of an aircraft, 25 to improve the braking capacity thereof by redirecting forward at least a portion of the thrust generated by the turbojet engine. In this phase, the inverter obstructs the cold flow vein and directs the latter towards the front of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels of the aircraft. The means used to achieve this reorientation of the cold flow 30 vary according to the type of inverter. However, in all cases, the structure of an inverter comprises movable covers (or doors) movable between a closed position or "direct jet" in which they close this passage and an open position or "reverse jet" in which they open. in the nacelle a passage intended for the deviated flow. These covers may perform a function of deflection or simply activation of other deflection means. 3027066 2 In the case of a thrust reverser with grids, also known as a cascade reverser, the reorientation of the air flow is carried out by deflection grids, the hood having only a simple function sliding to discover or cover these grids. The translation of the movable cowl takes place along a longitudinal axis substantially parallel to the axis of the nacelle. Reversed thrust flaps, actuated by the sliding of the hood, allow an obstruction of the cold flow vein downstream of the deflection grids, so as to optimize the reorientation of the cold flow to the outside of the nacelle.

Such a hood can either: be of quasi-annular shape, extending without interruption from one side to the other of a suspension pylon of the assembly formed by the turbojet engine and its nacelle, such a hood being designated by the Anglo-Saxon terms "O-duct", by allusion to the ferrule shape of such a hood, or in fact comprise two half-covers each extending over a half-circumference of the nacelle, such a hood being designated by the Anglo-Saxon terms "D-duct". The sliding of a cowl between its "direct jet" and "reverse jet" positions is conventionally performed by a plurality of actuators, of the electro-electric type (for example: worm gear actuated by an electric motor and moving a nut ) or hydraulic (cylinders actuated by pressurized oil). Typically, there are four or six actuators, namely respectively two or three actuators distributed on each half of the thrust reverser, on either side of the suspension pylon. However, in the case where at least one actuator arranged to move the movable cowl is broken, this failure is not directly detected. The present invention aims to facilitate the detection of a failure of at least one of these actuators, simply and reliably. This object of the invention is achieved with a thrust reverser for a turbojet engine nacelle comprising at least one movable cowl mounted on a fixed structure of the inverter between a closed position, in which it ensures the aerodynamic continuity of the nacelle and deactivates means for deflecting at least a portion of the air flow, and an opening position in which it opens a passage in the nacelle and activates said deflection means, each movable cowl being able to be moved between these two positions by actuators, the thrust reverser 3027066 being characterized in that it comprises at least one failure detection device comprising a retractable stop, controlled by at least one activation means, said stop being retractable between: a retracted position, when the movable cowl makes a normal travel, in which the stop is deactivated; and an extended position of detection, in case of predetermined over-travel of the movable cowl, in which the stop is activated and forms an obstacle to closing the movable cowl with respect to the fixed structure, said over-travel being detected by the means activation. Indeed, when opening the movable cowl to the open position, and because of the aerodynamic forces, the actuators mainly allow to slow the stroke of the movable cowl at the opening. In this configuration and in the case of a faulty or broken actuator, the aerodynamic forces will be supported by a then reduced number of viable actuators, so that the moving cowl is made to over-travel. However, and still in this configuration, when an actuator is faulty, the opening of the movable cowling is still possible and the deflection means of the thrust reverser can be activated, ensuring the safety of the aircraft especially during a landing phase to help braking the plane.

Thanks to the invention, the failure detection device makes it possible, during the predetermined over-travel of the moving cowl, to activate the activation means controlling the deployment of the retractable stop in the deployed or detection position. In such an extended position of the retractable stop, and during closing, that is to say during the movement of the movable cover towards the closed position, the movable cover comes into contact and bears, no longer against the structure fixed thrust reverser to ensure aerodynamic continuity of the nacelle but against said retractable stop. As a result, the aerodynamic continuity is no longer ensured 30 thus forming a visible discontinuity including the pilot or technicians. This discontinuity then allows the rapid detection of the failure of an actuator. Advantageously, the activation means is mechanical. Such a characteristic makes it possible to detect a failure of an actuator even in the event of any electrical damage.

According to an advantageous technical characteristic, the mechanical activation means is a lever connected to the retractable stop by a gear.

According to a particular technical configuration, the lever is arranged to be driven by the movable cowl in case of over-travel of the latter, this lever being preferably placed in the path of a trigger arm of the movable cowl. In this way the over-stroke is detected by the activating means when the triggering arm causes the lever in its over-travel. More specifically, the choice of the longitudinal distance, in the position of closure of the inverter, between the lever, and generally between the activation means, and the triggering arm makes it possible to define substantially the value of the normal stroke. maximum of the movable cowling beyond which the movable cowl 10 will over-travel. In one configuration, the movable cowl release arm is located at an upstream end of the movable cowl. Advantageously, the failure detection device comprises retaining means for elastically imparting to the detection device one or more positions (s) of equilibrium. Such a characteristic is particularly advantageous because it allows, during an over-travel of the moving cowl lower than the predetermined over-travel, the return to the equilibrium position of the detection device, in particular in the position a retracted position . Advantageously, the detection device has mounting and dismounting positions, each being separated from an equilibrium position, under elastic stresses of the retaining means. This allows, in particular during maintenance operations, an automatic return to the equilibrium position of the detection device, thereby facilitating handling of the movable hood by a technician.

According to a particular technical configuration, the retaining means are elastically engaged with at least one rotation shaft of the lever or a rotating shaft of the retractable stop geared together. According to one variant, the retaining means comprise at least one flat disposed between two springs. This flat is preferably secured to one of the rotation shafts of the lever or the retractable stop. The springs may be, for example, spring wires, leaf springs or any other equivalent resilient means. As mentioned above, this allows, during an overtravel primer beyond the normal stroke of the movable cowl but without exceeding the predetermined over-travel, to create an elastic return of the detection device to a balance position 3027066 corresponding to the retracted position once the constraint exerted by the movable cowl released. According to another aspect, the invention relates to a turbojet engine nacelle comprising a front air intake section, a median section intended to surround a turbojet engine fan and a rear section, the nacelle being remarkable in that it is equipped with at least one thrust reverser comprising all or part of the aforementioned characteristics. Other features and advantages of the present invention will emerge in the light of the description which follows, and on examining the appended figures, in which: FIG. 1 is a schematic overall representation of a nacelle of turbojet engine having a thrust reverser according to an embodiment, the inside of which is seen in transparency; FIG. 2 is a schematic representation in longitudinal half-section of the nacelle of FIG. 1; FIGS. 3 and 4 are general views of a thrust reverser according to one embodiment; FIG. 5 illustrates a front view of the thrust reverser of FIGS. 3 and 4; FIGS. 6, 7 and 8 are views in section along the section AA of FIG. 5, respectively in a closed position of the mobile cowl, in an open position of the mobile cowl and in a position in which a device detecting form obstacle to closing the movable hood; Figures 9 and 10 are detailed views of a failure detecting device of a thrust reverser actuator in the position illustrated in Figure 6; FIGS. 11, 12 and 13 are detailed views of a failure detection device in the position illustrated in FIG. 7; FIGS. 14 and 15 illustrate the detection device respectively in a retracted and deployed position; Figures 16, 17 and 18 are detailed views of a failure detection device in the position illustrated in Figure 8; FIG. 19 illustrates the retracted and deployed equilibrium positions of the detection device as well as the mounting and dismounting positions spaced apart from said equilibrium positions. FIG. 20 illustrates a particular kinematics of the detection device in the event of disassembly of the mobile cowl.

In all of these figures, identical or similar references denote identical or similar organs or sets of members. With reference to FIGS. 1 and 2, a nacelle 2 is intended to constitute a tubular housing for a turbojet engine 20 and serves to channel the flows of hot air F1 and cold F2 generated by this turbojet engine 20, as indicated in the preamble. of the present description. This nacelle 1 is intended to be suspended from a pylon 29, itself fixed under a wing of an aircraft. As indicated previously, the nacelle 2 has, in general, a structure comprising an upstream section 21 forming an air inlet, a median section 22 surrounding the fan 201 of the turbojet engine 20 and a downstream section 23 surrounding the turbojet engine 20. The downstream section 23 comprises an external structure 24 comprising a thrust reverser 1 and an internal structure 26 of the jet engine 3 of the turbojet defining, with the external structure 24, the vein of the cold stream 7, in the case of the twin-turbo jet engine nacelle. as presented here. The thrust reverser 1 comprises a cover 3, mounted on a fixed structure 4 of the inverter 1, said cover being movable in translation relative to this fixed structure 4 in a direction substantially parallel to the longitudinal axis A of the 20 nacelle 2. This cover 3 is adapted to move alternately from a closed position (position shown in Figures 1 and 2) in which it ensures the aerodynamic continuity of the lines of the downstream section 23 of the nacelle 2 and covers grids 25 of deflection of air flow, at an open position in which it opens a passage 25 in the nacelle 1 by discovering these deflection grids 25. The deflection grids 25 each have a plurality of deflection vanes. As illustrated in FIG. 2, the fixed structure 4 of the outer structure 24 of the downstream section 23 further comprises a front frame 27 which extends upstream the fixed structure 4 and ensures the attachment of the downstream section 23. with the middle section 22 surrounding the fan 201 of the turbojet 20. The translation of the movable cowl 3 downstream of the nacelle 2 releases therein an opening through which the cold stream F2 of the turbojet engine can escape at least partially this flow portion being reoriented towards the front 35 of the nacelle by the deflection grids 25, thereby generating a counter-thrust capable of contributing to the braking of the aircraft.

The orientation of the cold flow towards the deflection grids 25 is effected by a plurality of inversion flaps (not shown), distributed on the inner circumference of the movable cowl 3, each mounted pivoting between a retracted position in which these flaps ensure the internal aerodynamic continuity of the cold flow stream F2 5 and an extended position in which, in reverse thrust situation, they at least partially close this vein and deflect the cold flow through the deflection grids. Referring now more particularly to Figures 3, 4 and 5, on which we can see a thrust reverser 1 according to the invention.

This thrust reverser 1 has a structure comprising a mobile cover 3 of quasi-annular shape, slidable along rails (not visible) to discover deflection vane grids 25 placed between the movable cover 3 and a section passage of cold air flow F2 to deviate. Locking doors (not visible) are arranged inside the structure so as to be able to pivot and move from a position in which they do not interfere with the passage of the flow of air F2 to a position in which they block at least partially this passage. In order to coordinate the opening of the movable cowl 3 with a closing position of the locking doors, these are mechanically connected to the movable cowl 3 by hinges and a system of rods (not shown).

The displacement of the movable cowl 3 between: a closed position, in which it ensures the aerodynamic continuity of the nacelle 2 and deactivates means of deflection of at least a part of the air flow, and an open position in which it opens a passage in the nacelle and 25 activate said deflection means is provided by a set of actuators 5, for example electromechanical, mounted on the front frame 27. In this case, the movable cowl 3 is actuated to the using four electromechanical actuators each comprising a mechanical rod 5a controlled by an associated control box 5b comprising an electric motor. Figures 6, 7 and 8 illustrate a thrust reverser 1 according to a section AA of Figure 5, in different positions of the movable cover 3. Moreover, and for the purpose of improving the understanding of the detection device 6 in these different positions: FIGS. 9 and 10 refer to detailed views of the position as illustrated in FIG. 6; Figures 11, 12 and 13 refer to detailed views of the position as illustrated in Figure 7; and Figures 16, 17 and 18 refer to detailed views of the position as shown in Figure 8.

Indeed, Figures 6 and 7 (and those attached thereto) respectively illustrate a closed position and an open position of the movable cowl 3 of the thrust reverser 1 when all the actuators 5 operate smoothly. or normal, that is to say that no failure hinders their actions. Between these two open and closed positions, the movable cowl 3 10 carries a normal travel Cl. In case of failure of at least one of the actuators 5, when opening the movable cowl to the open position and, due to the aerodynamic forces, the actuators 5 have the main function of slowing down the stroke of the movable cowl 3 at the opening.

In this configuration and in the case of a faulty or broken actuator 5, the aerodynamic forces will be supported by a then reduced number of viable actuators 5, so that the movable cowl 3 is made to perform an over-stroke. that is to say to translate from a distance beyond the normal stroke Cl. The thrust reverser 1 according to the invention comprises a detection device 6 arranged on the one hand to detect this over-stroke. and on the other hand, to allow a person such as a pilot or a technician to easily detect the failure. The failure detection device 6 comprises a retractable stop 7, controlled by an activation means 8, said stop 7 being retractable between: a retracted position, when the movable cover 3 makes a normal travel, in which the stop 7 is disabled; and an extended detecting position, in case of predetermined over-travel of the movable cowl 3, in which the stop 7 is activated and forms an obstacle to the closing of the movable cowl 3 with respect to the fixed structure 4, said over-running being detected by the activation means 8. In this way, and thanks to the invention, the fault detection device 6 makes it possible, during the predetermined over-travel of the mobile cowl 3, to activate the activation means 8 controlling the deployment of the retractable stop 7 in the deployed position or detection.

In such a position, and during the closing, that is to say during the movement of the movable cowl 3 towards the closed position, an upstream end 31 of the movable cowl 3 comes into contact and bears no longer against the fixed structure 4 of the thrust reverser 1 to ensure the aerodynamic continuity of the nacelle 2 5 but in abutment and abutment against said retractable stop 7 which forms an obstacle to its good closure. Such a position is illustrated in Figure 8 and those attached thereto. As a result, the aerodynamic continuity is no longer ensured thus forming a visible discontinuity including the pilot or the technicians 10 responsible for maintenance. This discontinuity then allows the rapid detection of the failure of at least one of the actuators 5. The fixed structure 4 further comprises, in addition to the front frame 27, a rear frame 28 located downstream of said front frame 27, the grids 25 deflecting airflow being located between the front 27 and rear 28 frames.

The activation means 8 is here mechanical, as the detection device 6. This allows to overcome the electrical constraints while ensuring a simple and reliable operation of the detection device 6. More precisely, in this embodiment, the activation means 8 comprises a lever 9 connected to the retractable stop 7 by a gear system 10.

In particular, the lever 9 is configured to be driven by the moving cowl 3 in case of over-travel of the latter, and placed in the path of a trigger arm 30 of the movable cowl 3. In the embodiment here illustrated, the assembly comprising the activation means 8 and the retractable stop 7 intermeshed together is located at the rear frame 28 of the fixed structure 4 and the trigger arm 30 is placed at the upstream end 31 of the In this way it is possible to predetermine the over-travel according to the configuration of the thrust reverser 1, in particular as a function of the distance between the lever 9 and the trigger arm 30 of the movable cowl 3 30 delimiting the normal stroke Cl, but also depending on the lever arm formed by the lever 9 and the gear ratio of the gear 10 pivotally connecting said lever 9 and the retractable stop 7. The detection device 6 comp makes retaining means 11 for elastically imparting to the detection device 6 two equilibrium positions P1, P2.

Such a characteristic is advantageous because it allows, during an over-travel of the relatively small moving cowl, in particular less than the predetermined over-travel, the return to the equilibrium position of the detection device 6, in particular in the retracted position Pl.

In this way, the retractable stop 7 will not be permanently positioned in an intermediate position at the positions P1 and P2 which would be likely to hinder the translation of the mobile cowl 3 in a normal use or maintenance frame. This makes it possible, in any event, to take account of a margin of error in the over-travel without this being prejudicial to the good functioning of the thrust reverser 1. The retaining means 11 comprise a In particular, the lever 9 and the retractable stopper 7 are each carried by a separate rotating shaft 12, 13 comprising, over part of their circumference, teeth forming portions of gearwheels meshing with each other. . These rotation shafts 12, 13, placed parallel to each other, are rotatably mounted relative to two walls 40 arranged radially relative to the longitudinal axis A of the thrust reverser 1 and located on both sides of the gearing 10. The axes of rotation of the shafts 12, 13 extend transversely, that is to say perpendicularly to the axis of translation of the movable cowl 3. In others In other words, these two walls 40 support the shafts 12, 13 of rotation and define a space inside which the gear 10 is placed. The rotation shaft 13 of the retractable stop 7 has at its base 70 a portion of toothed wheel and two flats 14 on either side of said gear portion forming a portion of the gear 10. In other words, the flats 14 are disposed between the retractable stop 7 and one of the walls 40. Each of the flats 14 has substantially a diamond shape, each of which stops es presents a rounding.

Each of the flats 14, integral with the rotation shaft 13, is disposed between spring wires 15 so that it is elastically engaged with said spring wires 15. In fact, depending on the rotation of the spring With the shaft 13 carrying the retractable lever 7, the distance between the two spring wires 15 varies via the flats 14 between positions of retracted equilibrium P1 and deployed P2 of said lever 7, corresponding to positions in which said wires springs 15 engage substantially rectilinear sides of the associated flat portion 14.

Figures 14, 15 illustrate the detection device 6 in such retracted positions P1 and deployed P2, respectively. If at least one of the actuators 5 is broken, the movable hood retreating and just after its end of travel Cl moves beyond its normal travel C1 in normal operation so that its release arm 30 comes into contact with the lever 9 of the activation means 8 then in equilibrium position P1 (see FIG. 14). The mobile cover 3 thus performs an over-travel so that, in this configuration, the lever 9 driven by the release arm 30 pivots about its axis of rotation carried by its rotation shaft 12 whose gear 10 allows 10 d pivoting the abutment 7 about its axis of rotation carried by the rotation shaft 13. When the lever 9 pivots at an angle greater than an angle a, it automatically positions itself in equilibrium position P2 (see FIG. 15) by the action of the spring wires 15 on the flats 14 of the stop 7 retractable (see section DD, Figure 13). At the end of over-travel, the mobile cover 3 stops translating and the release arm 30 is found between the positions P1 and P2 thus allowing the reclosing of the movable cover 3. The angle a corresponds to an angle strictly less than the angle of movement of the lever 9 between the retracted position P1 and the deployed position P2 of the retractable stopper 7. When the lever 9 pivots by an angle less than a, the latter is elastically constrained to return to the position P1.When the lever 9 pivots by an angle greater than a, it automatically positions itself in equilibrium position P2. In other words, the position of the lever 9 when it forms an angle with respect to the position P1 corresponds to an intermediate position most elastically unstable. Preferably this angle a is between 10 and 45 degrees, and more preferably between 10 and 30 degrees. Advantageously, the angle a is substantially equal to half the pivoting angle of the lever 9 between the two retracted positions P1 and deployed P2. Thus, the retractable stop 7 of the detection device 6 is deployed to receive, during the closure of the mobile cover 3, a stop 35 anti-closure of said movable cover 3 to ensure a clearance .11 (see in particular FIGS. 18). The stop 35 anti-closure is located at a bottom of an interior space of the movable cowl 3 inside which are housed the airflow deflection grids 25 in the closed position.

The anti-closure stop 35 and the detection device 6 are arranged to intersect locally at the retractable stop 7 in the closed position and in normal operation, that is to say when the stop 7 is in the retracted position Pl. This makes it possible in particular to improve the compactness of the detection device 6 by reducing a useful length of the retractable abutment 7 defined by the distance between its base 70 integral with the rotation shaft 13 and a distal end 5 71 arranged to receive in contact and in support the movable cowl 3, in particular the anti-lock abutment 35. Indeed, this anti-lock abutment 35 comprises two lateral walls 36 extending substantially longitudinally with respect to the axis of the pod 2 These side walls 36 are vis-à-vis one another and spaced from each other transversely of a width large enough to accommodate at least a portion of the device of detection 6 in the closed position. The retractable abutment 7 has at its distal end 71 a front wall 72 extending transversely over a greater distance than the width separating the side walls 36 of the anti-closure abutment 35.

The side walls 36 are arranged so that, in the closed position, the distal end 71 of the abutment 7 in the retracted position P1 is placed above said side walls 36, for example thanks to a suitable height or notches arranged at this effect in the side walls 36, while the base 70 of the retractable stop 7 is housed between said side walls 36 (see in particular Figures 9 and 10). Moreover, these side walls 36 are placed on the path of the retractable stop 7 when it is in the deployed position P2. The front wall 72 extending transversely over a greater distance than the width separating the side walls 36, the front wall 72 is then adapted to receive in contact 25 and in abutment each of the edges of the side walls 36 in the deployed position P2 (see FIG. in particular Figures 16 and 17). Such an arrangement makes it possible in particular to reduce the useful length of the retractable stopper 7. In the opposite case, to ensure the same clearance without such an anti-closure abutment 36, it would then be necessary to increase the length of the abutment 7 retractable. However, a greater useful length of the retractable stop 7 also implies a useful space inside the movable cover 3 more important to allow its pivoting. In our case, an anti-closure stop arranged to intersect locally with a portion of the detection device 6 in the closed position of the movable cover 3 and in the retracted position P1 of the stop 7 and to be in contact and against the abutment 7 in the deployed position P2 makes it possible to reduce the mass and the volume of the thrust reverser 1, which is a fundamental objective in the field of aeronautics. FIGS. 16, 17 and 18 are detailed views in the position illustrated in FIG. 8. Indeed, and in this position, after the predetermined over-travel, the closing stroke Cl of the movable cowl 3 is reduced by one value equal to the game it thanks to the stop 35 anti-closure which comes into contact and bears against the retractable stop 7 of the detection device. In the illustrated embodiment, the movable cowl 3 carries a normal travel Cl equal to 515 mm corresponding to the normal operation of the thrust reverser 1. The detection device is activated by the activation means 8 when it is activated. the movable cowl overtravel 14.5 mm beyond this race Cl. The retractable stop is thus in the deployed position P2 after having traveled a total translation of 529.5 mm corresponding to the sum of the distances of the race Cl and over-race. Once the retractable stopper deployed 7, the closing stroke C1 of the movable cowl 3 is reduced by 30 mm corresponding to the value of the game il. FIG. 19 illustrates, on the same figure, the positions of retracted balance P1 and deployed P2 of the detection device as well as mounting positions P3 and disassembly P4.

Indeed, the detection device 6 has mounting and dismounting positions P3, P4, each being separated from a balanced position P1, P2, under elastic stresses of the retaining means 11. Thus, during maintenance of the thrust reverser 1, the movable cowl 3 can be mounted and disassembled without damaging the mechanism because the lever 9 can occupy different positions and automatically returns to the normal operating positions P1 and P2. FIG. 20 illustrates the kinematics of the detection device 6 in the particular case of disassembly of the movable cowl 3. In this example, the displacement of the movable cowl 3 during disassembly 30 is indicated by an arrow. During this translation, the release stop 30 of the movable cover 3 comes into contact with the lever 9 of the activation means 8 and causes it to pivot. Said lever is moved from the equilibrium position P1 to the equilibrium position P2, then beyond to disassemble the movable cowl 3, to a position P3 35 in which the lever 9 is separated from the path of the movable cowl 3 to allow its withdrawal. The position P3 corresponds to a biased elastic stressing position since it is moved away from the equilibrium positions P1, P2 so that, once the movable cover 3 has been pulled out, the lever 9 is no longer in contact and bears against the release arm 30, returns to the closest equilibrium position, namely the position P2.

5 When reassembling the moving hood, the same reverse phenomenon occurs. Indeed, the movable cowl will force the lever 9 from the position P2 to the position P1, then beyond to the off-equilibrium position P4 (see FIG. 19), and once the lever 9 is no longer in contact and resting against the release arm 30, returns to the nearest equilibrium position, namely the position Pl.

In this way, the detection device is simple and reliable to use and does not require any specific maintenance operation to ensure assembly and disassembly of the movable cover 3. Preferably such a detection device 6 is located in the vicinity of each of the actuators 5 of the thrust reverser 1.

In fact, because of the local stresses exerted on the movable cowl 3 in the position where it comes into contact and bears against the retractable stop 7 (see FIGS. 8 and 16-18 associated), and because of a certain flexibility of the movable cowl 3, it will deform so that game he then created is not uniform all around the said movable cowl and will be visible only locally at the cylinder 20 or the retractable stop 7 is then deployed. In this way, it is easy to detect the failed cylinder. The invention is described in the foregoing by way of example. It is understood that the skilled person is able to achieve different embodiments of the invention without departing from the scope of the invention.

For example, the structure of the detection device 6 can be reversed so that the assembly comprising the activation means 8 and the retractable stopper 7 intermeshed together can be placed at the upstream end 31 of the movable cover 3 and the release arm 30 may be placed at the rear frame 28 of the fixed structure 4. However, the solution illustrated in the figures allows the liner 3 to be lightened by the fact that the release arm 30 has a mass and a bulk lower than the gear 10 of the activation means 8 and the retractable stop 7. In an alternative configuration, the detection device 6 may comprise an electronic activation means provided with a movable hood position detector (s). 3 controlling at least one actuator to position the retractable stopper 7 in the determined position.

Claims (10)

REVENDICATIONS1. Thrust reverser (1) for a nacelle (2) of a turbojet engine (20) comprising at least one movable cowl (3) mounted on a fixed structure (4) of the inverter (1) between a closed position, in which it ensures the aerodynamic continuity of the nacelle (2) and deactivates means for deflecting at least a portion of the air flow, and an opening position in which it opens a passage in the nacelle and activates said deflection means, each mobile cowl (3) being able to be moved between these two positions by actuators (5), the thrust reverser 10 (1) being characterized in that it comprises at least one failure detection device (6) comprising a retractable stop (7), controlled by at least one activation means (8), said stop being retractable between: a retracted position, when the movable cover (3) makes a normal stroke, in which the stop (7) is disabled; and an extended detecting position, in case of predetermined over-travel of the movable cowl (3), in which the stop (7) is activated and forms an obstacle to the closing of the movable cowl (3) with respect to the fixed structure (4), said over-travel being detected by the activating means (8). 2. thrust reverser (1) according to claim 1, characterized in that the activation means (8) is mechanical. 3. thrust reverser (1) according to claim 2, characterized in that the actuating means (8) mechanical is a lever (9) connected to the stop (7) retractable by a gear (10). 4. Thrust reverser (1) according to claim 3, characterized in that the lever (9) is arranged to be driven by the movable cowl (3) in case of over-travel of the latter, preferably this lever ( 9) is placed in the path of a trigger arm (30) of the movable cowl (3). 5. thrust reverser (1) according to claim 4, characterized in that the release arm (30) of the movable cowl (3) is located at an upstream end (31) of the movable cowl. 6. thrust reverser (1) according to any one of the preceding claims, characterized in that the detection device (6) comprises retaining means (11) for elastically imparting to the detection device (6) one or more equilibrium position (s) (P1, P2). 35 7. thrust reverser (1) according to any one of the preceding claims, characterized in that the detection device (6) has mounting positions and dismounting (P3, P4), each being separated from a equilibrium position (P1, P2), under elastic stresses of the retaining means (11). 8. Thrust reverser (1) according to any one of the preceding claims, characterized in that the retaining means (11) are elastically engaged with at least one rotation shaft (12) of the lever (9) or a rotating shaft (13) of the stop (7) retractable meshed together. 9. thrust reverser (1) according to any one of the preceding claims, characterized in that the retaining means (11) comprise at least one flat (14) disposed between two springs (15). 10. A turbojet engine nacelle (2) comprising a front air inlet section, a median section intended to surround a fan of the turbojet engine and a rear section, the nacelle being characterized in that it is equipped with at least one thrust reverser (1) according to any one of the preceding claims.