Lost-motion actuating device for a thrust reverser

Abstract

The invention relates to an actuating device (1) for an aircraft thrust reverser system (3) comprising at least one thrust reverser device (2), the actuating device (1) comprising at least one motorized drive unit (10) situated on an upstream side of a first lost-motion lock (12a) and designed to actuate an input shaft (11) of this first lock (12a), the first lock being designed, when unlocked, to actuate an output shaft driving a flexible synchronization shaft (13) situated on a downstream side, and the actuating device (1) further comprising at least one first movable jack rod (14b) which is mechanically connected to the flexible synchronization shaft and secured to a movable element of the thrust reverser device (2), the first movable rod belonging to a first set of movable rods which is associated with the first lock (12a).

Description

Lost motion actuation device for thrust reverser

[0001] FIELD OF THE INVENTION

[0002] The present invention relates to a thrust reverser system for an aircraft.

[0003] An aircraft, particularly an airplane, is typically powered by turbomachines, particularly turbojets, each housed in nacelles designed to channel the airflows generated by the turbomachine. Such a nacelle may also house various equipment, such as a thrust reverser system.

[0004] The role of a thrust reverser is to facilitate the aircraft's landing. In operation, the thrust reverser system redirects some of the airflow forward, creating thrust in the opposite direction to the aircraft's direction of travel and thus helping to reduce its speed. This system thus complements wheel braking.

[0005] There are several different types of thrust reverser systems. These include door reversers and grid reversers.

[0006] A thrust reverser system relies on a mechanism for actuating movable elements such as cowls or doors, which are movable between two positions, in order to engage or disengage the thrust reverser function.

[0007] Generally speaking, thrust reverser systems (door or grid) rely on the movement of a cowl, particularly in translation for a grid reverser, by means of actuators. The translation is generally in a direction substantially parallel to a longitudinal axis of the nacelle.

[0008] A distinction can be made between single-piece cowls (or "O-duct" in English terminology) and "D-duct" cowls made up of two half-cowls. According to this terminology, the letters O and D refer to the shape of the single-piece cowl (annular or substantially annular) or, respectively, of a half-cowl. Document FR 2 914 700 describes in more detail a single-piece cowl for a thrust reverser system.

[0009] The hood translation is typically carried out by means of a plurality of actuators. Typically, there can be 4 or 6 actuators per hood, or 2 or 3 per half-hood in the case of a "D-duct" architecture.

[0010] These actuators are typically actuating cylinders, the movable rod of which is integral with the hood or half-hood.

[0011] Obviously, it is crucial to avoid any accidental sliding of the cylinder, because opening the cowl at an inopportune moment (during flight, in particular) can have extremely serious consequences for the aircraft and fatal for its crew.

[0012] Safety devices are therefore necessary, including locking systems acting directly on the actuators, to prevent unwanted opening of the hood. The certification rules for a flight reverser require the installation of three locks, including two so-called primary locks, for each hood or each half-hood. The third lock is independent of the first two so as to prevent the same command from opening the reverser in flight in an unwanted manner.

[0013] Patent application FR3008741 describes integrating a lock directly into the drive cylinder, using a lost motion drive cylinder.

[0014] This "lost movement" mechanism consists of a first part of an input movement being used to unlock the lock, then, once the lock is unlocked, the subsequent movement being used to deploy the movable rod.

[0015] When closing the thrust reverser, the movable rod retracts into the cylinder body and then engages the locking system again when the first part of the input screw's travel is reached. Movement between the locking position and the closed stop is not prevented.

[0016] In patent application FR3008741, it is proposed to have a single motorized drive unit (or PDU for “Power Drive Unit”) in English) which powers two drive cylinders associated with the same half-cover. Each cylinder is also associated with a lost movement lock.

[0017] This proposal is not entirely satisfactory because it has been noted through experience that the locks do not necessarily unlock synchronously, which results in the hood not always opening smoothly but rather by "jerks". In addition, and above all, this proposal requires having one lock per cylinder, which is very penalizing in terms of manufacturing cost, maintenance, and mass.

[0018] SUMMARY OF THE INVENTION

[0019] One of the aims of the invention is to improve the state of the art.

[0020] It allows the mass of the thrust reverser system to be reduced, and the corresponding costs, by using a single lock for several moving cylinder rods, while avoiding unwanted unlocking of this lock by the forces coming from the different moving rods downstream.

[0021] For these purposes, according to a first aspect, the present invention can be implemented by an actuating device for an aircraft thrust reverser system comprising at least one thrust reverser device, said actuating device comprising at least one motorized drive unit located on a so-called upstream side of a first lost motion lock and adapted to actuate an input shaft of said first lost motion lock, said first lock being adapted to, when unlocked, actuate an output shaft driving a flexible synchronization shaft located on a so-called downstream side, opposite said upstream side, and said actuating device further comprising at least one first movable cylinder rod, mechanically connected to said flexible synchronization shaft and secured to a movable element of said thrust reverser device,said first movable rod belonging to a first set of movable rods associated with said first lost movement lock.,

[0022] Thus, according to the invention, the synchronization of the different cylinders associated with a single lock, downstream of the latter, makes it possible to share this lock for several cylinders, which makes it possible to reduce the mass of the on-board equipment, as well as the associated costs.

[0023] This also helps to avoid jolts and smooth the movements of the moving rods of the cylinders, by synchronizing the cylinders without dead travel.

[0024] According to preferred embodiments, the invention comprises one or more of the following features which may be used separately or in partial combination with each other or in total combination with each other: - said output shaft is directly connected to a second movable cylinder rod, also integral with a movable element of said thrust reverser device and belonging to said first set of movable rods; - said motorized drive unit is adapted to actuate a second lost motion lock, adapted to actuate a second set of movable rods; - said thrust reverser device comprises two movable elements and in which said first assembly is integral with a first movable element, and said second assembly is integral with a second movable element; - said first and second locks each comprise a preload arrangement provided to oppose any movement when an imposed force is less than a preload threshold. - a brake is inserted between said first lock and said second lock; - the actuating device further comprises a flexible coupling shaft capable of transmitting forces between the first and second sets of movable rods.

[0025] A second aspect of the invention can be implemented by a thrust reversal system comprising a thrust reversal device and an actuating device as previously described.

[0026] A third aspect of the invention can be implemented by an aircraft nacelle comprising at least one thrust reversal system as previously described.

[0027] Other characteristics and advantages of the invention will appear on reading the following description of a preferred embodiment of the invention, given by way of example and with reference to the appended drawings.

[0028] BRIEF DESCRIPTION OF THE FIGURES

[0029] The accompanying drawings illustrate the invention: Figure 1 represents a schematic view of a propulsion unit of an aircraft comprising a turbomachine and incorporating thrust reverser systems according to embodiments of the invention. Figure 2 schematically represents a thrust reversal system according to a first embodiment. Figure 3 schematically represents a thrust reversal system according to a second embodiment. Figure 4 schematically represents a thrust reversal system according to a third embodiment. Figure 5 schematically represents a thrust reversal system according to a fourth embodiment.

[0030] DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0031] The thrust reversal system according to the invention, and its embodiments, is suitable for being installed in an aircraft, in particular an airplane, equipped with at least one turbomachine, in particular a turbojet.

[0032] Figure 1 shows a schematic of a propulsion system including a thrust reverser system.

[0033] The propulsion unit comprises a turbomachine shrouded by a nacelle 100. The nacelle is formed around a longitudinal axis corresponding substantially to the navigation axis.

[0034] Conventionally, during operation of such a turbomachine, an air flow 101 enters the nacelle 100 through an air inlet located upstream of the nacelle, passes through a fan 107 and divides into a primary flow 101a and a secondary flow 101b.

[0035] The primary flow 101a flows in a primary vein of the gas circulation passing through a gas generator.

[0036] The secondary flow 101b flows in a secondary vein 102 surrounding this gas generator and located between the latter and the inner envelope of the nacelle 100.

[0037] The thrust reverser system comprises fixed elements, integral with the nacelle 100, and mobile elements. These mobile elements comprise a mobile element 103, or cowl, as well as shutters 104 actuated by connecting rods 105.

[0038] According to one embodiment, this mobile element comprises an opening, which may for example comprise a single-piece cover (case “O-duct”) or two half covers (case “D-duct”).

[0039] These moving elements allow the configuration of the thrust reverser to be modified.

[0040] In Figure 1, the thrust reverser is in a thrust configuration called direct jet. In this configuration, the movable cowl 103 is in a closed position in which it covers the grids 106.

[0041] The shutters 104 are in a retracted position in which they do not obstruct the secondary vein 102.

[0042] Thus, in direct jet, the thrust reverser allows the secondary flow 101b to be channeled towards the rear of the propulsion unit so that this secondary flow drives the propulsion of the aircraft.

[0043] In a thrust reversal configuration, called reverse jet, the movable cowl 103 is slid into an open position in which it releases an opening corresponding to the opening of the grilles 106.

[0044] Furthermore, this translation of the movable hood 103 causes the shutters 104 to deploy so as to conceal the secondary vein 102.

[0045] Thus, in reverse jet, the shutter flaps 104 divert all or part of the secondary flow 101 b towards the grids 106. These typically comprise a blade to direct this secondary flow towards the front of the propulsion unit.

[0046] In this thrust reversal configuration, the secondary flow 101 b thus generates a braking counterthrust of the aircraft.

[0047] Several moving elements, and several thrust reverser systems, can be arranged on the same nacelle. It is thus classic to have a thrust reverser device on each side of the same nacelle, each of these thrust reverser devices being associated with a respective actuation device.

[0048] As is known per se, an aircraft may have several propulsion units, each of the nacelles being able to have a thrust reversal system.

[0049] Each thrust reverser system comprises a thrust reverser device, comprising the movable elements previously described, for example, as well as an actuating device.

[0050] Typically, a command may be transmitted to the actuating device(s). Upon receipt of this digital command, they may actuate the thrust reversing device(s) themselves.

[0051] Actuation can be mechanical, depending on the types of thrust reverser devices.

[0052] Figure 2 shows the main elements of a thrust reverser system 3 which are useful for understanding the invention and its implementations. It is clear that a thrust reverser system can include many other elements. Likewise, the elements shown are shown in a schematic and functional manner, and simplified so as to facilitate understanding of the invention.

[0053] In the illustrated example, the thrust reversal system 3 comprises an actuating device 1 and a thrust reversal device 2.

[0054] In this embodiment, two movable rods, 14a, 14b of cylinders are integral with a movable element of a thrust reverser device 2. When the movable rods move in translation, they cause the opening, or closing, of the movable element (hood or half-hood for example).

[0055] The movable rods can enter and exit a body (not shown) of the jacks, depending on a movement applied to an input shaft, 11, actuated by a motorized drive unit 10. The jack is therefore designed to convert a movement, for example rotary (applied to the input shaft 11) into a translational movement (generated on the movable rods 14a, 14b).

[0056] The motorized drive unit 10 can be controlled by a control unit via an electrical connection (not shown). This control unit can itself be connected to the control members associated, for example, with the engine computer, or with the instrument panel of the aircraft. The control unit is provided to transmit commands to the motorized drive unit 10 to start or stop a rotary engine.

[0057] The rotary movement generated by the motorized drive unit 10 actuates, for example in rotation, the input shaft 11, for example by means of a flexible shaft (or cable), of a lost movement lock 12. This lock comprises an output shaft 19 actuated as a function of the movement applied to the input shaft when the lock is unlocked.

[0058] According to one embodiment, this lock 12 can be integrated within the same mechanical device as the jack. According to another embodiment, the lock is structurally separate from the jack.

[0059] In a deployment phase, a movement is applied to the input shaft 11 in order to translate the movable rod 14a so as to actuate the thrust reverser device 2 (it is assumed in this example that the movable rod 14a is translated towards the left of the figure).

[0060] The lost motion lock 12 is conventionally adapted to nominally block the translational movement of the movable rod 14a. To do this, a locking part can mechanically prevent the translation of the movable rod and be actuable so as to allow this translation. This part can be placed directly on the movable rod or on the rotation of the shaft.

[0061] Typically, the first movements applied to the input shaft 11 do not cause the translation of the movable rod 14a, until the unlocking of the lock is carried out. This unlocking can correspond to a position of the input shaft or a predefined number of turns.

[0062] Subsequent movements of the input shaft cause the translation of the movable rod 14a, mechanically secured to the output shaft of the lock. The lock can then actuate the movable shaft 14a.

[0063] Conversely, when the input shaft is in reverse rotation, the movable rod 14a is returned in reverse translation (towards the right of the figure), up to the locking position.

[0064] According to the proposed device, this lock is shared for several movable rods 14a, 14b. This sharing makes it possible in particular to lighten the structure of the actuating device 1, but also to reduce its manufacturing and maintenance costs.

[0065] According to this device, in addition, the output shaft 19 of the lock drives a flexible synchronization shaft (or cable) 13. Other equivalent mechanical transmission mechanisms can also be used to perform the function of the flexible synchronization shaft.

[0066] An element 16 may be provided adapted to recover the movement of the output shaft 19 and transmit it to the flexible shaft (or cable) 13. Different mechanical mechanisms, known per se, are possible to carry out this transmission of movement. For example, a bevel gear may be used.

[0067] The flexible synchronization shaft 13 is provided to actuate the movable rod 14b in translation, for example by means of a mechanical connection box 15. This mechanical connection box is in particular provided to convert the rotary movement of the flexible shaft 13 into translational movement applied to the movable rod 14b of the jack. It may comprise the body of the jack in which the movable rod 14b can be inserted in a folded position.

[0068] The flexible synchronization shaft 13 thus makes it possible to synchronize the translation of the movable rod 14b with that of the movable rod in direct engagement with the output shaft 19 of the lock. In other words, the same input shaft 11 allows the two movable rods 14a, 14b to be operated in perfect synchronization, as soon as the lock 12 is unlocked.

[0069] Synchronization is carried out by an arrangement positioned downstream of the lock 12, so that the movable rods can only translate, in a united manner, once the lock is released.

[0070] It is understood that this example can be generalized to more than two movable rods. Indeed, the same synchronization arrangement can transmit the rotary movement to several mechanical connection boxes in order to cause the translation of as many movable rods. It is for example possible to connect several boxes to the same flexible synchronization shaft 13, or to have several synchronization shafts for the same lock 12.

[0071] Thus, according to this proposed device, the synchronization shaft 13 is positioned downstream of the lost movement lock 12, that is to say at the output of the latter and opposite the input shaft 11 (upstream side).

[0072] This synchronization downstream of the lock makes it possible to protect against any unwanted unlocking of the lock by movements which would take place on the cylinders attached to the flexible synchronization shaft.

[0073] In particular, the force going up on the movable rod 14b, and the synchronization shaft 13 cannot unlock the lock 12.

[0074] When unlocked, the lock can actuate all of the movable rods 14a, 14b. The movable rod 14b, mechanically connected to the flexible synchronization shaft 13, is thus actuated by the output shaft 19 of the lock 12.

[0075] Figure 3 schematically illustrates another embodiment in which no movable rod is in direct engagement with the output shaft 19 of the lock 12.

[0076] In this embodiment, the lock 12 is dissociated from the set of movable rods of the jacks. The lock is shared for this set of jacks, and the movement is transmitted via a return 16 to this set of jacks.

[0077] In the example of Figure 3, 4 cylinders (and 4 movable rods 14a, 14b, 14c, 14d) are shown.

[0078] These movable rods may be provided to actuate the same movable element of a thrust reverser device 2, for example a cowl or a half-cowl depending on the embodiment of this thrust reverser.

[0079] According to other embodiments, as shown in the example of Figure 3, it can be provided that a subset of these movable rods (for example the pair 14a / 14b) actuates a first movable element 2a and that the other subset (for example the pair 14c / 14d) actuates a second movable element 2b. For example, in the context of a “D-duct” type architecture, the first subset of rods is secured to a first half-cover 2a, while a second subset of rods is secured to the second half-cover 2b. Without loss of generality, the mechanism described applies with a single movable element.

[0080] The embodiment described in Figure 3 is largely similar to that of Figure 2. The common parts will not be explained again.

[0081] Similarly, the input shaft 11 drives in synchronized rotation several flexible synchronization shafts 13a, 13b, 13c, 13d, each of which can actuate in translation one or more (2 in the example shown) movable rods, when the lock is unlocked.

[0082] Mechanical connection boxes, 15a, 15b, 15c, 15d, may be provided to transmit and convert the rotary movement of the flexible synchronization axes into several synchronized translational movements, applied to the movable rods, respectively 14a, 14b, 14c, 14d.

[0083] We see in this example that a single lost movement lock is shared for 4 moving rods.

[0084] For example, according to embodiments, the same lost-motion lock 12 may be deployed for one or more moving elements, for example for the 2 half-hoods of a “D-duct” type structure. At the same time, synchronization between the movements of the moving rods is ensured by the flexible synchronization shaft(s) (or cable), both in their start since they all start moving when the lock is unlocked, and in their speed of movement since they are all actuated by the same input screw and the same motorized drive unit.

[0085] Figure 4 illustrates another embodiment, in which the actuating device 1 further comprises preload arrangements, 17a, 17b.

[0086] In this embodiment, a single motorized drive unit 10 actuates the input shafts 11a, 11b of two locks, 12a, 12b respectively. Each lock 12a, 12b has an output shaft, 19a, 19b respectively, for actuating a set of movable rods (14a / 14b and 14c / 14d respectively) by means of synchronization (16a / 13a / 15b and 16c / 13b / 15d respectively).

[0087] It may happen that one of the two locks 12a, 12b is defective. These cases are relatively rare and are generally detected by routine inspections of the aircraft's equipment. However, it may be worthwhile to protect against a hidden failure of such a lock.

[0088] In the event of a lock failure that no longer allows locking, the locking mechanism may be deficient, such that the movable rods associated with this lock can no longer be locked. In such a case, in flight, the force corresponding to these rods is no longer blocked by the lock and can be communicated, upstream of the lock, to the input screw then to the flexible shaft towards the motorized drive unit 10. By its architecture, the latter can also transmit this force to the other flexible shafts, and therefore to another lock. If this force is sufficient, the input shaft will be actuated until this other lock is unlocked and the corresponding movable rods are actuated in translation.

[0089] In other words, a failure of one lock can cause the other lock(s) engaged with the same motorized drive unit to unlock in a chain. Such a situation must obviously be avoided because it would be catastrophic for the aircraft.

[0090] According to embodiments of the invention, mechanisms may be provided to prevent such chain unlocking of the locks.

[0091] In the embodiment of Figure 4, it is provided that the first lock 12a and the second lock 12b each comprise a preload arrangement, respectively 17a, 17b.

[0092] These preload arrangements 17a, 17b are provided to oppose any movement when a force imposed on them is less than a preload threshold.

[0093] Typically, a preload arrangement comprises one (or more) springs whose preload state corresponds to this preload threshold.

[0094] According to this embodiment of the invention, the preload threshold of a lock is provided to cover the mission profile for actuating the movable rods associated with the other locks seen by the movable rods and likely to fail (for example it can correspond to the limit forces during flight).

[0095] The preload must be sufficient to compensate for the sum of the external limit forces applied to the moving elements linked to the actuators

[0096] More precisely, - the preload threshold of the first lock 12a corresponds to a force corresponding to the movable rods of the second set 14c, 14d of movable rods, and - the preload threshold of the second lock 12b corresponds to a force corresponding to the first set of movable rods 14a, 14b.

[0097] These forces may further correspond to the sum of the forces generated by each of the moving rods of the respective set of moving rods.

[0098] Thus, if, for example, the lock 12b is faulty, the movable rods 14c, 14d are free to move. The external forces F c +Fd, where F c and Fd applied to the movable rods 14c, 14d respectively cause the translation of these rods.

[0099] To guard against this, the lock 12a is preloaded so that the preload threshold F pr scarf g e is such that F P recharge>F c +Fd.

[0100] Thus, the force generated by the free movements of the rods 14c, 14d will not be able to unlock the lock 12a. Therefore, the failure of the lock 12b does not lead to a chain unlocking of the other, or other, locks.

[0101] Alternatively, or in addition, a brake 20 may be provided between the input shafts of the lost motion locks.

[0102] This brake prevents chain unlocking, without having preload in the lost movement locks 12a, 12b.

[0103] Another implementation of the invention, illustrated in Figure 5, provides for the installation of a flexible coupling shaft 18, capable of transmitting the forces between the first and second sets of movable rods, without passing through the locks. Figure 5 reproduces the elements of Figure 4 which will not be described again.

[0104] This flexible shaft 18 has a stiffness greater than the stiffness allowing the unlocking of the locks 12a, 12b.

[0105] In a way, this flexible shaft blocks the transmission of forces which would otherwise pass freely through the motorized drive unit 10.

[0106] Thus, in the event of a lock failure, the free movement of the corresponding rods will be blocked and will not be reflected on the moving rods corresponding to the other lock.

[0107] For example, the flexible looping shaft 18 can be installed between a movable rod of the first set and a movable rod of the second set. In the example illustrated in FIG. 5, the flexible looping shaft 18 is installed between the mechanical connection boxes 15b, 15c, associated with the movable rods, respectively 14b, 14c, actuated by the flexible synchronization shafts 13a, 13b (in other words, which are not in direct engagement with the locks 12a, 12b). Of course, the present invention is not limited to the examples and the embodiment described and shown, but is defined by the claims. It is in particular susceptible of numerous variants accessible to those skilled in the art.

Claims

Claims 1. ^Actuation device (1) for a thrust reverser system (3) for an aircraft comprising at least one thrust reverser device (2), said actuating device (1) comprising at least one motorized drive unit (10) located on a so-called upstream side of a first lost-motion lock (12a) and adapted to actuate an input shaft (11) of said first lost-motion lock (12a), said first lock being adapted to, when unlocked, actuate an output shaft driving a flexible synchronization shaft (13) located on a so-called downstream side, opposite said upstream side, and said actuating device (1) further comprising at least one first movable cylinder rod (14b), mechanically connected to said flexible synchronization shaft and secured to a movable element of said thrust reverser device (2), said first movable rod belonging to a first set of movable rods associated with said first lost-motion lock (12a).

2. Device according to the preceding claim, in which said output shaft is directly connected to a second movable cylinder rod (14a), also integral with a movable element of said thrust reverser device (2) and belonging to said first set of movable rods.

3. Actuating device (1) according to one of the preceding claims wherein said motorized drive unit (10) is adapted to actuate a second lost movement lock (12b), adapted to actuate a second set of movable rods (14c, 14d).

4. Device according to the preceding claim, in which said thrust reverser device (2) comprises two movable elements (2a, 2b) and in which said first assembly (14a, 14b) is integral with a first movable element (2a), and said second assembly (14c, 14d) is integral with a second movable element (2b).

5. Actuating device (1) according to one of claims 3 or 4, wherein said first and second locks (12a, 12b) each comprise a preload arrangement (17a, 17b) provided to oppose any movement when an imposed force is less than a preload threshold.

6. Actuating device (1) according to one of claims 3 to 5, wherein a brake (20) is inserted between said first lock (12a) and said second lock (12b).

7. Actuating device (1) according to one of claims 3 to 6, further comprising a flexible coupling shaft (18) capable of transmitting forces between the first and second sets of movable rods.

8. Thrust reversal system (3) comprising a thrust reversal device (2) and an actuating device (1) according to one of claims 1 to 7.

9. Nacelle (100) for aircraft comprising at least one thrust reversal system (3) according to the preceding claim.]

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