Device for attaching the small end of the connecting rod of a thrust reverser cascade baffle

Abstract

A device for attaching the small end of a connecting rod (10) of a thrust reversing cascade baffle to an internal fixed structure (11) of a nacelle (2) of a turbojet engine (3), the device comprising a fitting (13) and a connection interface (14), the fitting being adapted to be fixed to the internal fixed structure (11), the connection interface forming a joint between the small end of the connecting rod (10) and the fitting (13). The device comprises a removable fork (19) adapted to cooperate with the connection interface (14), the fork (19) and the connection interface (14) being arranged inside the fitting (13).

Description

Technical Field

[0001] The present invention relates to cascade thrust reversers and, more particularly, to the attachment of the small end of the connecting rod of a thrust reversal flap. Background Art

[0002] An aircraft generally comprises a power train formed by a plurality of turbojet engines in order to provide the thrust required for the flight of the aircraft.

[0003] Each turbojet engine is housed in a nacelle that performs various functions, such as obtaining reverse thrust using thrust reversers, the purpose of which is to reduce the braking distance of the aircraft when landing by redirecting at least part of the thrust generated by the turbojet engine forward and thus generating counter-thrust that contributes to the braking of the aircraft.

[0004] A turbojet engine generally comprises an air intake and a fan which ensure compression of the air and separation of the air into a primary flow and a secondary flow.

[0005] The turbojet engine also comprises a primary flow path and a secondary flow path in which the primary air flow circulates through the compressor, the combustion chamber and the turbine.

[0006] More specifically, the thrust reverser blocks a downstream portion of the secondary flow path with a solid obstacle in order to redirect the secondary flow forward.

[0007] Modern aircraft are usually equipped with cascade reversers comprising a plurality of locking flaps hingedly mounted on a movable cowl that slides along tracks in order to reveal and / or hide the cascade vanes.

[0008] The cascade vanes are capable of redirecting the secondary airflow upstream of the nacelle when the aircraft is braking.

[0009] The movable cowl is longitudinally translatable between a closed position (commonly referred to as "direct jet" in which the vanes are concealed within the cowl) and an open position or "reverse jet" in which the vanes perform their deflection function by being exposed to the secondary flow path.

[0010] More specifically, the device comprises a plurality of links whose function is to connect the locking baffles to the inner structure of the nacelle (commonly referred to as the "Inner Fixed Structure (IFS)").

[0011] In other words, when the thrust reverser operates in direct jet, the locking flaps are maintained in the retracted position, but when the thrust reverser operates in reverse jet, they are deployed in order to deflect the secondary airflow.

[0012] In order to reduce the losses in aerodynamic performance at the interface between each of the links of the baffle and the points of attachment of these links to the fixed structure of the thrust reverser, it is known to use aerodynamic fairings.

[0013] However, this fairing has certain disadvantages, in particular relating to its attachment.

[0014] One of the known configurations is to attach the fairing to the structure of the nacelle, enclosing the connecting rod small end. This arrangement increases the space requirements of the fairing and impairs its aerodynamics.

[0015] Another solution is to integrate the fairing into the fitting at the small end of the connecting rod, which allows for optimised dimensions. However, this solution is less aerodynamically efficient.

[0016] Furthermore, the forces exerted on the fairing, which is typically made of plastic, may damage the fairing or even cause it to separate from the structure to which it is secured.

[0017] Therefore, the challenge is to improve aerodynamic flow while maintaining the arrangement at the small end of the connecting rod without using a fairing. Summary of the Invention

[0018] In view of the above, the subject of the present invention is a device for attaching the small end of the connecting rod of a thrust reversing blade cascade to the internal fixed structure of a turbojet nacelle, comprising a fitting suitable for being fixed to said internal fixed structure and a connection interface forming a joint between the small end of the connecting rod and the fitting.

[0019] The device comprises a removable locking device adapted to cooperate with the connection interface in order to lock the connection interface with respect to rotation, the locking device and the connection interface being arranged inside the fitting.

[0020] "Being arranged inside the fitting" means that no boss is formed on the shell of the fitting due to the volume of the connection interface and the fork. It should also be understood that the fork and the connection interface are confined in an internal space defined by the side facing the fitting.

[0021] The absence of bosses on the profile of the fitting improves aerodynamic flow.

[0022] However, in order to maintain a constant gap between the connection interface and the fitting, it is advantageous to use a mechanical component in the shape of a fork as means for locking the connection interface.

[0023] This configuration further improves aerodynamic performance while ensuring good stability of the small end of the connecting rod and thus maintaining the correct operation of the thrust reverser, since the fork is located inside the fitting.

[0024] Furthermore, such locking devices have a small thickness, which allows limiting the thickness of the fitting and therefore the impact on engine performance, thanks to the fact that they are housed inside the volume delimited by the fitting.

[0025] Advantageously, the connection interface comprises a first screw and a first nut capable of cooperating with said first screw.Thus, the screw is used as a pivot axis for the small end of the connecting rod.

[0026] It should be noted that the nut is advantageously of rectangular shape, which allows the first screw to be torqued.

[0027] Preferably, the first screw comprises at least one flat surface or at least one shoulder in contact with its base, and the removable locking device comprises a fork comprising at least one tooth extending along a transverse axis perpendicular to the longitudinal axis of the first screw, said at least one tooth cooperating with said at least one flat surface or said at least one shoulder.

[0028] This shoulder or flat surface allows locking the first screw in terms of rotation when the fork surrounds the first screw by means of the at least one tooth.

[0029] It should be noted that the twisting allows for approximately 1 / 4 turn.

[0030] The first screw may comprise a plurality of shoulders which may form, for example, a hexagonal shoulder.Similarly, the first screw may alternatively comprise, for example, the at least one shoulder in the shape of a hexagon, at least one flat surface or a plurality of flat surfaces.

[0031] As for the joint portion, the joint portion may include, for example, two side surfaces that preferably form an obtuse angle.

[0032] Alternatively, the first screw comprises at least one housing extending perpendicularly to the longitudinal axis of the first screw, and the removable locking device comprises a fork comprising a rod configured to be inserted into said housing.

[0033] In other words, by inserting a single tine of the fork into said cavity, the first screw is locked with respect to rotation.

[0034] The number of cavities in the first screw is selected according to the tightening torque between the first nut and the first screw.

[0035] Preferably, the device comprises retaining means arranged inside the fitting and capable of retaining the locking means in place.

[0036] When the cover is transferred from the closed position to the open position, the fork is subjected to forces, in particular shear forces, suitable for separating the cover from the fitting of the small end of the connecting rod, which may cause the first screw to loosen, resulting in a weakening of the mechanical strength of the device for attaching the small end of the connecting rod.

[0037] It is therefore advantageous to provide means for holding the fork in position in order to ensure the stability of the arrangement of the mechanical components of the device.

[0038] Advantageously, the retaining means comprise a resilient pin surrounding a bearing area integral with the fitting and passing through the locking means.

[0039] According to another variant, the retaining means comprise at least one rivet located on the locking means.

[0040] According to another variant, the retaining means comprise a second screw suitable for cooperating with a second nut.

[0041] It should be noted that since there is no relative movement between the fork and the fitting, torque tightening is sufficient here.

[0042] Preferably, the retaining means comprises a lockwire arranged between the second nut and the locking means and adapted to retain the second screw in position.

[0043] Advantageously, the distance between the holding device and the connection interface is between 12 mm and 200 mm.

[0044] Preferably, the small end of the connecting rod comprises at least two protrusions, which are perpendicular to the longitudinal axis of the connecting rod and are in contact with the locking device.

[0045] In order to reduce the angular oscillations of the connecting rod, consequences of aerodynamic loads, it is advantageous to integrate the at least two projections in the connecting rod small end so that they are in contact with the fork.

[0046] This also has the advantage of reducing the size of the other mechanical components arranged inside the fitting and originally having the function of limiting the angular travel of the connecting rod. Reduction of the width of the fitting, characterized by a reduction in the mass of the assembly and better aerodynamic performance.

[0047] According to another aspect, a cascade thrust reverser is provided, comprising a device for attaching at least one connecting rod small end of a thrust reverser flap as defined above.

[0048] Another subject of the invention is a nacelle for a turbojet engine for an aircraft, comprising a cascade thrust reverser as defined above. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Other objects, features and advantages of the present invention will become apparent on reading the following description given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0050] Figure 1 Schematically shows a turbojet engine nacelle for an aircraft according to the prior art, the turbojet engine nacelle comprising a cascade thrust reverser;

[0051] Figure 2A and Figure 2B each showing an axial section of a cascade thrust reverser according to the prior art, respectively in a direct jet position and in a reverse jet position;

[0052] Figure 3A and Figure 3B A first embodiment of an apparatus for attaching the small end of a connecting rod of a thrust reversing cascade baffle is schematically shown;

[0053] Figure 4 A second embodiment of the attachment device is shown;

[0054] Figure 5A and Figure 5B shows a perspective view of a third embodiment of an apparatus for attaching a connecting rod small end;

[0055] Figure 6 and Figure 7 An example of a device according to the invention for holding a removable fork arranged inside the attachment device is shown, and

[0056] Figure 8A and Figure 8B An embodiment of the connecting rod small end and its arrangement in the device is shown. DETAILED DESCRIPTION

[0057] Figure 1 A propulsion unit 1 is shown comprising a nacelle 2 of generally tubular structure along a longitudinal axis X.

[0058] The propulsion unit also comprises a turbojet engine 3 , for example a bypass turbojet engine, suitable for generating a primary air flow and a secondary air flow by means of a rotating fan 4 .

[0059] The secondary air flow circulates outside the turbojet engine 3 through an annular flow path 5 formed between the two walls of the nacelle 2 .

[0060] The primary and secondary flows are ejected from the turbojet engine 3 through an ejection nozzle 6 situated at the rear of the nacelle 2 and comprising more particularly a primary nozzle 61 capable of ejecting the primary flow.

[0061] The injection nozzle 6 further includes a secondary nozzle 62 capable of injecting a secondary flow.

[0062] In order to reduce the braking distance of the aircraft during landing, the nacelle 2 comprises mechanical cascade thrust reversers 7 .

[0063] More specifically, the mechanical thrust reverser system serves to redirect at least part of the thrust generated by the turbojet engine 3 towards the front of the nacelle 2 , thereby generating reverse thrust.

[0064] For this purpose, the cascade vanes 8 are concealed in a movable cowl 9 that can slide along rails from a closed position to an open position in order to reveal said cascade vanes, which allows redirecting the secondary airflow towards upstream of the nacelle 2 .

[0065] Figure 2A The closed position is shown in FIG, and this figure shows that the movable cover 9 comprises a plurality of locking flaps 12 forming a joint with said movable cover 9.

[0066] The connecting rod 10 is pivotally mounted on a locking baffle 12 and on an internal fixed structure 11 , generally known as IFS, which is adapted to surround the rear of the turbojet engine 3 .

[0067] The connecting rod 10 includes a first joint 101 on the locking baffle 12 and a second joint 102 on the internal fixing structure 11 corresponding to the small end of the connecting rod 10 .

[0068] Thus, in this closed position, the secondary flow is able to circulate in the annular flow path 5 and generate, together with the primary flow, a flow FD which generates thrust.

[0069] To generate reverse thrust, actuators such as hydraulic cylinders ( Figure 2B ) causes the cover 9 to slide so that the annular flow path 5 is closed by the locking baffle 12.

[0070] This consequently causes the secondary flow to be redirected by the cascade blades 8 into a reverse flow (here indicated by reference FI) to generate reverse thrust.

[0071] In order to ensure the correct operation of the connecting rod 10 and therefore the correct operation of the reverser, it is advantageous if the fitting 13 surrounds the small end of the connecting rod 10 (e.g. Figure 3A shown). Figure 3A is a view of a section along the longitudinal axis X.

[0072] The device DIS for attaching the small end of the connecting rod 10 is located inside the space delimited by the fitting 13 .

[0073] This device DIS comprises a connection interface 14 forming a pivot connection for the small end of the connecting rod 10 , and a removable fork 19 capable of partially surrounding the connection interface 14 .

[0074] More specifically, the connection interface 14 includes a first screw 140 of a recessed or hexagonal socket head type and a first nut 141 capable of cooperating with the first screw 140 .

[0075] Advantageously, the shape of the first nut 141 is adapted to match the shape of the orifice of the accessory 13 into which it is inserted, so as to lock the first nut in terms of rotation.

[0076] The fork 19 thus has the function of locking the first screw 140 in terms of rotation. The fork is also attached to the accessory 13 and is locked in place by retaining means which in this example comprise a resilient pin 21 surrounding a bearing area 20 integral with the accessory 13 and passing through the fork 19.

[0077] The device DIS for attaching the small end of the connecting rod 10 also comprises a first ring 16 arranged between the small end of the connecting rod 10 and the fitting 13 and capable of absorbing the forces transmitted by the connecting rod 10 towards the fitting 13 through the first screw 140 when the thrust reverser 7 is in operation.

[0078] The first ring 16 also acts as a stop for the connecting rod 10 to reduce any undesired movements of the connecting rod 10 , in particular angular oscillations.

[0079] A second ring 17 is also arranged between the connecting rod 10 and the fork 19. Firstly, this second ring allows the fork 19 to be held in position by holding it against the shoulder ring 18 at the fitting 13.

[0080] Secondly, the second ring 17 allows the ball joint of the connecting rod 10 to be locked at the fitting 13 by means of the assembly comprising the at least one shoulder of the first screw 140 , the first ring 16 and the first nut 141 .

[0081] Therefore, the fork 19 has a gap with the second ring 17 , the shoulder ring 18 and the first screw 140 .

[0082] Figure 3BAn axial view along axis B as defined in the previous figure is shown.

[0083] The fork 19 comprises a first tooth 190 and a second tooth 191 extending along a transverse axis perpendicular to the longitudinal axis of the first screw 140 .

[0084] As for the first screw 140 , it comprises in this example a shoulder in contact with its base, which shoulder is inserted between the first tooth 190 and the second tooth 191 , locking the first screw 140 in terms of rotation.

[0085] Alternatively, as Figure 4 As shown, the first screw 140 includes a plurality of flat surfaces 25 in a hexagonal shape in contact with the base 26 thereof.

[0086] In this embodiment, the first screw 140 is inserted between the first tooth 190 and the second tooth 191 in the same manner.

[0087] like Figure 5A As shown, another variant is that a first screw 140 is inserted with at least one circular cavity 27 extending perpendicularly to the longitudinal axis of said screw 140 .

[0088] like Figure 5B As shown, the fork 19 here comprises a single rod 193 which is inserted into said cavity 27 in order to lock the first screw 140 with respect to rotation.

[0089] It should be noted that cavity 27 may be a through cavity, which allows doubling the number of positions into which rod 193 may be inserted into cavity 27 .

[0090] In addition, if Figure 6 As shown, as an alternative to the elastic pin 21 , a second screw 22 capable of cooperating with a second nut 23 may be mentioned.

[0091] Optionally, a locking wire may be placed between the second nut 23 and the fork 19 to improve the retention of the second screw 22 .

[0092] Another variation is, Figure 7 As shown, rivets 24 are used as means for retaining the fork 19 .

[0093] Figure 8A An embodiment of the small end of a connecting rod 10 according to the present invention is shown.

[0094] The small end of the connecting rod 10 here comprises at least two protrusions 28 perpendicular to the longitudinal axis of the connecting rod 10 .

[0095] like Figure 8BAs shown, which shows an axial view along the longitudinal axis X, the angular oscillations of the connecting rod 10 are reduced by bringing the two protrusions 28 into contact with the fork 19 .

[0096] This also has the advantage of reducing the size of other mechanical components, in particular the width of the first ring 16. Thus, the width of the fitting 13 is reduced while improving its aerodynamic profile.

Claims

1. A device (DIS) for attaching the small end of a connecting rod (10) of a thrust reversing cascade baffle to an internal fixed structure (11) of a nacelle (2) of a turbojet engine (3), said device comprising a fitting (13) adapted to be fixed to said internal fixed structure (11) and a connection interface (14), said fitting forming a joint between the small end of the connecting rod (10) and said fitting (13), characterised in that The device comprises a removable locking device (19) adapted to cooperate with the connection interface (14) in order to lock the connection interface with respect to rotation, the locking device (19) and the connection interface (14) being arranged inside the fitting (13).

2. The device according to claim 1, wherein The connection interface (14) comprises a first screw (140) and a first nut (141) capable of cooperating with the first screw.

3. The device according to claim 2, wherein The first screw (140) comprises at least one flat surface (25) or at least one shoulder in contact with its base (26), and the locking device (19) comprises a fork-shaped portion, the fork-shaped portion comprising at least one tooth (190, 191) extending along a transverse axis perpendicular to the longitudinal axis of the first screw (140), the at least one tooth (190, 191) cooperating with the at least one flat surface (25) or the at least one shoulder.

4. The device according to claim 2, wherein The first screw (140) comprises at least one cavity (27) extending perpendicularly to the longitudinal axis of the first screw (140), and wherein the locking device (19) comprises a fork comprising a rod (193) configured to be inserted into the cavity (27).

5. Device according to any one of claims 1 to 4, comprising retaining means arranged inside the fitting (13) and capable of retaining the locking means (19) in place.

6. The device according to claim 5, wherein The retaining device comprises a resilient pin (21) which surrounds a bearing area (20) which is integral with the fitting and passes through the locking device (19).

7. The apparatus according to claim 5, wherein The retaining means comprises at least one rivet (24) which is located on the locking means (19).

8. The apparatus according to claim 5, wherein The retaining means comprises a second screw (22) adapted to cooperate with a second nut (23).

9. The apparatus according to claim 8, wherein The retaining means comprises a locking wire arranged between the second nut (23) and the locking means (19), suitable for retaining the second screw (22) in place.

10. The apparatus according to claim 5, wherein The distance between the retaining device and the connection interface (14) is between 12 mm and 200 mm.

11. The apparatus according to any one of claims 1 to 4, wherein The small end of the connecting rod (10) comprises at least two protrusions (28), which are perpendicular to the longitudinal axis of the connecting rod (10) and in contact with the locking device (19).

12. A cascade thrust reverser (7) comprising a device (DIS) for attaching the small end of the connecting rod (10) of the thrust reverser cascade baffle to an internal fixed structure (11) of the nacelle (2) of a turbojet engine (3) according to any one of claims 1 to 11.

13. A nacelle (2) of a turbojet engine (3) for an aircraft, comprising a cascade thrust reverser (7) according to claim 12.

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