THRUST REVERSER FOR TURBOJET ENGINE

Abstract

This summary relates to a thrust reverser (20) for a turbojet engine mounted on an engine nacelle pylon (40), comprising a fixed part (29), a movable part (39), coaxial and mounted in translation with respect to the fixed part (29) and sealingly inserted against the fixed part (29) by blocking an air outlet passage in a closed state whereas the air outlet passage is freed up in the extended state, and a single actuating device (38) including a beam (31), a slider (30), and a driving device, configured to drive the movable part (39) in translation with respect to the fixed part (29), wherein the beam (31) comprises a stop (32) taking the form of a protuberance protruding on a radially outer surface (31a) of the beam (31) and configured to have a clearance (j) with respect to said engine nacelle pylon (40).

Claims

1. A thrust reverser (20) for a turbojet engine (10), said turbojet engine being mounted on an engine nacelle pylon (40) and having a center-line (A), comprising a fixed part (29), designed to be mounted on the turbojet engine (10) so as to encircle the latter, a movable part (39), coaxial and mounted in translation with respect to the fixed part (29) between a closed state and an extended state, the movable part (39) being sealingly inserted against the fixed part (29) by blocking an air outlet passage in the closed state, whereas the air outlet passage is freed up in the extended state, and a single actuating device (38) including a beam (31), secured to the fixed part (29), extending axially along the outer surface of the fixed part (29), a slider (30), secured to the movable part (39), mounted in translation on the beam (31), and a driving device (33), configured to drive the movable part (39) in translation with respect to the fixed part (29), wherein the beam (31) or the slider (30) comprises a stop (32) taking the form of a protuberance protruding on a radially outer surface (31a) of said beam (31) or slider (30) and configured to have a clearance (j) in the closed state with respect to said engine nacelle pylon (40).

2. The thrust reverser (20) as claimed in claim 1, comprising a single driving device (33).

3. The thrust reverser (20) as claimed in claim 1 or 2, wherein the driving device (33) is mounted between the beam (31) and the slider (30).

4. The thrust reverser (20) as claimed in any of claims 1 to 3, wherein at least one stop (32) is carried by the beam (31).

5. The thrust reverser (20) as claimed in claim 4, wherein the stop (32) is located at a distance from the front end of the beam (31) between 2.3 and 3.1 times the length of the track of the movement of the movable part between the closed position and the extended position (39), preferably between 2.5 and 2.8 times the length of the track of the movement of the movable part (39).

6. The thrust reverser (20) as claimed in any of claims 1 to 5, wherein the stop (32) is configured to touch the engine nacelle pylon (40) beyond a given level of bending of the beam (31) corresponding to a deformation of the beam under the effect of an emergency operation of the thrust reverser (20).

7. The thrust reverser (20) as claimed in any of claims 1 to 6, wherein the beam (31) or the slider (30) has a second stop (32) positioned in a common radial plane with the first stop (32) and configured to have a clearance with respect to the engine nacelle pylon (40) substantially equal to the clearance (j) of the first stop (32).

8. The thrust reverser (220) as claimed in any of claims 1 to 7, wherein at least one stop (32) comprises a contact element (32B).

9. The thrust reverser (120) as claimed in any of claims 1 to 8, wherein at least one stop (132) includes a depth-adjusting device (132C).

10. The thrust reverser (20) as claimed in any of claims 1 to 9, wherein at least one stop (32) comprises a bracket (32A) and a contact element (32B) designed to be replaced.

11. The thrust reverser (20) as claimed in claim 10, wherein the contact element (32B) is removable and intended to be replaced in the event of wear.

12. A propulsion assembly comprising a turbojet engine (10) and a thrust reverser (20) as claimed in any of claims 1 to 11.

13. An aircraft comprising a propulsion assembly as claimed in claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The appended drawings are schematic and above all aim to illustrate the principles of the summary.

[0052] On these drawings, from one figure to the other, identical elements (or element parts) bear the same reference signs. Furthermore, elements (or element parts) belonging to exemplary embodiments which are different but have a similar function bear, in the figures, numerical references incremented by 100, 200, etc.

[0053] FIG. 1 is a side view of an example of an aircraft.

[0054] FIG. 2 is an axial section view of an example of a mixed-flow turbojet engine.

[0055] FIG. 3 shows a side view of an example of a thrust reverser, where the nacelle is partially shown.

[0056] FIG. 4 shows a perspective view of this thrust reverser.

[0057] FIG. 5 is a section view along an axial plane of this thrust reverser.

[0058] FIG. 6 is a perspective view of the thrust reverser comprising the outer cowls and bearing on an engine nacelle pylon.

[0059] FIG. 7 shows an enlargement of area VII of FIG. 6.

[0060] FIG. 8 is a diagram showing a first example of a stop.

[0061] FIG. 9 is a diagram showing a second example of a stop.

[0062] FIG. 10 shows a variant embodiment of the thrust reverser of FIG. 3.

DESCRIPTION OF THE EMBODIMENTS

[0063] FIG. 1 is a schematic side view of an example of an aircraft 1, comprising a fuselage 2 from which wings 4 extend laterally from the root 3. The aircraft 1 has a stabilizer at the back, comprising a fin 5 to which two rudders 6 are attached. A turbojet engine 10 is mounted on either side of the fuselage 2, aft of the fuselage, by way of an engine nacelle pylon.

[0064] The example of an aircraft 1 of FIG. 1 is solely illustrative, and any other disposition of the structural elements is possible according to the general knowledge of those skilled in the art. In particular, the turbojet engines 10 are not limited to two, and can be disposed under the wing 4 rather than aft of the fuselage 2.

[0065] FIG. 2 shows an example of a mixed-flow turbojet engine 10 having a center-line A shown by the dot-and-dash lines. The flow of air through the turbojet engine 10 is shown on the diagram from left to right. The inlet of the turbojet engine 10 has a fan 11 drawing the air inside the turbojet engine 10. The air flow is then divided into a primary air flow I and a secondary air flow II. The primary air flow I is successively compressed by a low-pressure compressor 12 and a high-pressure compressor 13, respectively driven by a low-pressure turbine 16 and a high-pressure turbine 15. Between the compressors 12, 13 and the turbines 15, 16 is located a combustion chamber 14 receiving the air compressed by the compressors 12, 13 and into which the fuel is injected in order to perform the combustion. The combustion gases depart from the combustion chamber 14 driving the turbines 15 and 16 and meet at the outlet the secondary air flow II, the latter crossing the turbojet engine 10 on the radial periphery of the primary air flow I. A mixer 17 is positioned at the outlets of the turbines 15, 16 to promote the mixture of the two gas flows I, II and thus optimize the total thrust of the gas exiting through the nozzle 18, at the back end of the turbojet 10.

[0066] The example of the turbojet engine 10 of FIG. 2 is illustrative and the turbojet engine 10 is not limited to this embodiment.

[0067] A back part of the turbojet engine 10 has a thrust reverser 20, located on a circumference of the turbojet engine 10.

[0068] FIGS. 3 and 4 respectively show side and perspective views of this thrust reverser 20, wherein a cowl 24 has not been shown in order to reveal the inner structure of the thrust reverser 20; this cowl 24 will be shown with reference to FIG. 5.

[0069] The thrust reverser 20 comprises a fixed part 29, comprising the fixed parts in the reference frame of the engine, and a movable part 39, in translation with respect to the fixed part 29.

[0070] The fixed part 29 comprises an attaching flange 21, making it possible to attach the thrust reverser 20 on a casing of the turbojet engine 10, a fixed casing 22, surrounding an air path of the engine, and a fixed cowl 24 (visible on FIG. 5) surrounding the fixed casing 22.

[0071] The movable part 39 is coaxial with the fixed part 29 and comprises at least a reverser grid 23, extending over a circumferential contour of the turbojet engine 10, and a movable cowl 25. The movable cowl 25, provided downstream of the grids 23, is configured to be sealingly inserted against the fixed part 29 in the closed state. In the closed state, the grid 23 is located between the casing 22 and the fixed cowl 24. The movable part further comprises at least one blocking panel forming an obstacle to the flow exiting the engine in order to deviate the air flow through the grids 23 during the operation of the reverser 20, i.e. in the extended state.

[0072] The thrust reverser comprises an actuating device 38, comprising a beam 31, a slider 30 and a driving device 33. The beam 31 forms a single part with the fixed part 29 and extends axially along the outer surface of the fixed part 29; the slider 30 is secured to the movable part 39 and translationally mounted on the beam 31; the driving device 33 is used to drive the movable part 39 in translation with respect to the fixed part 29, for example being mounted between the beam 31 and the slider 30.

[0073] The driving device 33 takes the form of a single actuator 33. The action of this actuator 33 is described with reference to FIG. 5.

[0074] FIG. 5 is a section along an axial plane of the thrust reverser 20. In particular, FIG. 5 shows the cowls 24, 25 and the grids 23.

[0075] When the thrust reverser 20 is not in operation, the movable cowl 25 is added in a sealed manner against the fixed part 29, thus preventing the passage of the air through the grids 23. The fixed casing 22 thus bears at its downstream end a ring seal 27 against which a border 28 of the movable part 39 is applied.

[0076] The movable part 39 is mounted in axial translation with respect to the fixed part 29 and the action of the driving device 33 allows the thrust reverser 20 to enter an extended state wherein the movable cowl 25 and the grids 23 are disengaged from the fixed cowl 24 such that an air passage is left between the fixed part 29 and the movable part 39. This air passage crosses the grids 23, the orientation of which makes it possible to redirect the air flow upstream, and thus slow down the aircraft 1.

[0077] During the operation of the thrust reverser 20, the forward expulsion of the gas causes a backward thrust on the thrust reverser 20, which is transmitted to the turbojet engine 10 by the driving device 33 to slow down the aircraft 1. Due to the unbalance of the structure of the thrust reverser 20 caused by the presence of a single actuating device 38, a bending moment is generated and causes the bending of the thrust reverser 20 in a radial direction along an axis passing through the driving device 33.

[0078] In other words, the actuating device 38 is radially moved outward, and the thrust reverser 20 is moved as a consequence. The level of movement is greater the further downstream the point in question is. This makes it possible to cause levels of movement in the order of tens of mm, or even in the order of hundreds of mm at points of the back end of the reverser 20.

[0079] This bending deformation poses the risk of preventing the translation of the movable part 39 against the fixed part 29, and requires an increase in the functional clearances between the movable part 39 and the fixed part 29.

[0080] To limit the deformation, provision is made for a stop 32 in the form of a protuberance on a radially outer surface 31a of the beam 31. This stop 32 is located facing the engine nacelle pylon 40.

[0081] Provision is made for the stop 32 to have a clearance j with respect to the engine nacelle pylon 40, such that the stop 32 bears on the pylon beyond a given level of bending of the actuating device 38.

[0082] To effect this coupling, the clearance j between the stop 32 and the engine nacelle pylon 40 can be chosen to have a value between 5 mm and 25 mm, preferably between 10 mm and 20 mm in order to limit contact in the event of an emergency operation. In this example, the clearance j is of 16 mm.

[0083] In particular, in order to promote the take-up of stresses by the engine nacelle pylon 40, the stop 32 is located on a distal part of the beam 31, at a distance from the back end of the beam 31 between 2.3 and 3.1 times the length of the track of movement of the movable part between the closed position and the extended position, and preferably between 2.5 and 2.8 times the track of movement of the movable part. In this example, the stop is located at a distance from the back end of the beam 31 equivalent to 2.65 times the track of the movable part.

[0084] As can be seen in FIG. 7, corresponding to area VII of FIG. 6, the stop 32 is composed of a bracket 32A and a contact element 32B. The bracket 32A is a structural element by which the stop 32 is secured to the beam 31, while the contact element 32B makes it possible to distribute the contact across the counteracting surface of the pylon 40, reduce the transmission of vibrations between the turbojet engine 10 and the pylon 40, and limit hammering effects against the pylon 40, for example in the event of high-amplitude vibrations of the beam.

[0085] For example, the contact element 32B can take the form of a pad made out of an elastomer material or out of other polymer materials such as nylon, Ertacetal or Teflon. In addition, to limit damage to the engine nacelle pylon 40, the contact element 32B can be a wear part designed to be replaced, for example by being removable and made of a material of low hardness compared to the material of the bearing surface 50 of the engine nacelle pylon 40, in order to preferentially wear the replaceable contact element 32B.

[0086] The replacement of the contact element 32B can be defined according to a criterion of flight time, number of flights, number of use cycles of the thrust reverser 20, level of wear, after a use of the thrust reverser 20 in critical operation or any other criterion deemed relevant by those skilled in the art.

[0087] The engine nacelle pylon 40 has a surface counteracting to the stop 32, provided to constitute a bearing surface 50 of the stop 32. In particular, this bearing surface 50 can have a structure or material suitable for receiving the stop 32.

[0088] According to a first variant shown in FIG. 9, in order to adjust the clearance between the stop 132 and the bearing surface 150 of the pylon, for example when the contact element 132B has wear not requiring any replacement, the stop 132 has a depth-adjusting device 132C, i.e. a device for adjusting the radial extension of the stop 132 without disassembling the stop 132.

[0089] FIG. 10 shows a thrust reverser having a first stop 32 and a second stop 32 used to supply a second stress path from the reverser toward the engine nacelle pylon 40. This second stop 32 is located in the same radial plane as the first stop 32, and has the same clearance j as the first stop 32, in order to be used as a complement to the first stop 32 so that the two stops 32, 32 touch the engine nacelle pylon 40 at a same level of deformation of the beam 31, and thus taking up a bending stress as well as a torsional moment.

[0090] The second stop 32 may have the same structure as the first stop 32, and also comprise a bracket and a contact element designed to be replaced, as well as a depth-adjusting device.

[0091] The second stop 32 is not limited to this embodiment. In particular, it may be positioned at a point further forward or backward than the first stop 32, have a clearance different from the first clearance j or else touch the engine nacelle pylon 20 beyond a level of deformation greater than the given level of deformation.

[0092] Although the first invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the different embodiments illustrated/mentioned can be combined in additional embodiments. Consequently, the description and drawings must be considered in an illustrative sense rather than a restrictive one.