WO2015028735A1

WO2015028735A1 - Thrust reverser of a turbojet nacelle, comprising grids and cylinders fixed upstream of mobile hoods

Info

Publication number: WO2015028735A1
Application number: PCT/FR2014/051985
Authority: WO
Inventors: Guy Bernard Vauchel
Original assignee: Aircelle
Priority date: 2013-08-28
Filing date: 2014-07-30
Publication date: 2015-03-05
Also published as: FR3010145A1

Abstract

The invention relates to a thrust reverser of a turbojet nacelle, comprising mobile hoods (10) which retract in relation to a front frame (2) under the effect of cylinders (14), driving, by means of connecting links (24), the tilting of flaps (8) initially tucked away inside said hoods, in order to substantially close the annular cold air stream (4), and opening grids (12) arranged around said stream, which grids receive the cold air flow in order to send it back towards the front. The invention is characterised in that the rear ends of the grids (12) and the cylinders (14) are fixed upstream of the mobile hoods (10) and slide therewith, said grids and said cylinders being returned to inside a casing (18) of the front frame (2) when the reverser is closed.

Description

Thrust reverser of a turbojet engine nacelle, comprising grids and fixed jacks upstream of the mobile hoods

The present invention relates to a thrust reverser for an aircraft nacelle receiving a turbojet, and an aircraft nacelle equipped with such a thrust reverser.

The engine sets for the aircraft comprise a nacelle forming a generally circular outer envelope, comprising inside a turbojet arranged along the longitudinal axis of this nacelle.

The turbojet engine receives fresh air from the upstream or front side, and rejects on the downstream or rear side hot gases from the combustion of fuel, which give a certain thrust. For turbofan engines, fan blades arranged around this turbojet generate a large secondary flow of cold air along an annular vein passing between the engine and the nacelle, which adds a high thrust.

Some nacelles include a thrust reversal system that closes at least part of the annular cold air duct, and rejects the secondary flow forward to generate a braking thrust of the aircraft.

A known type of thrust reverser, presented in particular by the document FR-A1 -2758161, comprises rear movable covers that can slide axially backwards under the effect of jacks, by deploying flaps in the annular vein in order to at least partially close this vein. These flaps return the flow of cold air radially outward through grids discovered during this sliding, comprising blades that direct the flow forward.

When the thrust reverser is closed, the grids forming an annular structure connected from the upstream side to the fixed front structure forming a frame, and the jacks comprising their upstream ends connected to this front frame, are integrated into the thickness of the movable covers substantially at the same radial height. The flaps folded under the radially lower face of the grids, has a front end fixed by a pivot to an annular structure which is integral with the rear movable covers.

When the thrust reverser opens, the jacks retracting the movable hood to the rear, the fixed grids are gradually discovered at the same time as the flaps unfold to close the annular vein, to reject the air flow to outside through these grids that deflect it forward.

For an inverted flow, significant aerodynamic forces apply to the flaps, which are taken up by the integral annular structure of the movable covers.

However, a problem that arises is that this annular structure is notched to receive the cylinders which are housed radially in its thickness, which forces to have reinforcements and to increase the mass of this structure to obtain the necessary rigidity.

In addition, this type of thrust reverser poses a problem of interruption of the seal arranged in a direct jet between this annular structure and the fixed upstream structure, which must be cut when passing each cylinder. It is then necessary to arrange the seal to the passage of these cylinders, which reduces the reliability of the seal, and therefore the aerodynamic performance in direct jet.

The present invention is intended to avoid these disadvantages of the prior art.

It proposes for this purpose a thrust reverser of a turbojet engine nacelle, comprising movable cowls which recoil with respect to a front frame under the effect of jacks by driving by rods the tilting flaps initially located folded to the interior of these covers, to substantially close the annular cold air stream, and opening grids arranged around this vein which receive the cold air flow to return it to the front, characterized in that the rear end grids and jacks are attached upstream of the movable covers and slide with them, these grids and cylinders being retracted into a box of the front frame when the inverter is closed, and in that said jacks have a front end arranged radially, towards the inside of said box. An advantage of this thrust reverser is that the grids and cylinders being arranged upstream of the movable covers, the inner annular structure of these movable covers is not interrupted by the cylinders, which allows to easily achieve a rigid structure comprising a reduced footprint and limited mass. In addition one can also achieve a continuous seal between the flaps and the front frame, when the inverter is closed.

The thrust reverser according to the invention may further comprise one or more of the following features, which may be combined with one another.

Advantageously, when the inverter is closed, the cylinders are arranged radially below the grids. This arrangement makes it possible not to modify the grids at these jacks.

According to one characteristic of the invention, the thrust reverser comprises at least one control system disposed inside the box of the front frame, and access to said control system is achieved through at least one partially located hatch external of said box.

Advantageously, the box comprises an inner wall comprising towards the rear a curved portion facing outwards, forming an aerodynamic channel for guiding the air flow during the opening of the inverter. This improves the aerodynamic flow in reverse flow.

Advantageously, the curved portion of the inner wall has slots for the passage of the cylinders, the flaps comprising at the front a sealing surface bearing on the inner wall below the slots when the inverter is closed. We improve the aerodynamic passage in direct flow.

The front frame can be attached to the upstream structure by hooks arranged radially inwardly of this frame, to fix the complete inverter on the structure of the nacelle located upstream, which achieves a simple and effective fixation.

In this case the rear end of the cylinders can be fixed to the front frame on a fitting disposed near the hooks, which is a rigid attachment point. The box of the front frame can thus comprise a locking system of the movable cowl, comprising at least one lever whose downstream end is integral with said cowl and an upstream end of which is integral with the front frame, the upstream end being fixed on the fitting disposed near the hooks.

According to one embodiment, each flap comprises a front articulation fixed to the front of the movable hoods, and a rear articulation fixed to the rear end of a control rod comprising its front end fixed to the internal surface of the annular vein. .

According to another embodiment, each flap comprises an integrated long rod when the inverter is closed, in a longitudinal groove formed on the surface of the inner wall of the box, its rear end being linked by a hinge at the rear of this box. shutter, its front end being linked by a hinge to the front structure.

In this case, the front end of the long rod can be linked to the front frame by a fitting disposed near the hooks, which is a rigid attachment point.

In particular, the trailing end of the flaps may comprise an elastomeric pad coming into contact with the internal surface of the annular vein when these flaps are deployed, which limits the flow losses in reverse flow.

The invention also relates to a turbojet engine nacelle comprising a thrust reverser comprising any one of the preceding features.

The invention will be better understood and other features and advantages will appear more clearly on reading the description below, given by way of example with reference to the accompanying drawings in which:

- Figure 1 is a half-view in axial section through the axis of a cylinder, an inverter according to the invention which is closed;

FIG. 2 is a view of this inverter which is open;

FIGS. 3 and 4 are axial views passing through the locking system of this inverter which is presented respectively closed and open; - Figures 5 and 6 are axial views with a variant of the locking system, the inverter which is presented respectively closed and open;

- Figures 7 and 8 are axial views with a flap control link variant of this inverter which is presented respectively closed and open; and

- Figure 9 is a view of a mounting bracket of a jack on the structure.

Figures 1 and 2 show the rear part of a turbojet engine nacelle, comprising a front frame 2 fixed on the structure located upstream of this part, and two movable covers 10 fitted behind this frame, each forming a plane transverse a semicircle.

Each cover 10 is guided axially by longitudinal guiding means, which allow sliding backwards under the effect of jacks 14 bearing on the front frame 2.

Alternatively the nacelle may comprise a single movable cover 10 forming in a transverse plane a closed ring, which in the same way slides backwards to open the thrust reverser.

The secondary annular coolant vein 4 comprises a radially outer contour comprising flaps 8 fitted inside the movable covers 1 0, so as to give an aerodynamic continuity, and a radially internal contour formed by the fixed internal structure 6.

Grids 12 arranged flat around the annular vein 4, form a fully integrated ring in a box 18 of the front frame 2 when the inverter is closed, this ring being disposed radially just below the outer wall of this frame.

The rear end of the grilles 12 is fixed to a movable frame 16 stiffening the movable covers 1 0, comprising a transverse partition closing the front of these covers. The grids 12 can slide freely through openings in the front frame 2, in order to follow the movement of the covers 10 when the inverter opens.

Each jack 14 disposed substantially flat under the grids 12, in the box 18 of the front frame 2, has a front end disposed radially inwardly of this cavity, which is fixed by a fitting 30 to the front frame, and a rear end fixed to the movable frame 16, just below the grids, which leaves room below for the mechanism of the flaps 8. The ends of the cylinder 14 are fixed by transverse pivots.

Each flap 8 has a front hinge 20 fixed to a cover 10 substantially at the front wall of the movable frame 16, and a rear hinge 22 fixed to the rear end of a control rod 24 comprising its front end 26 fixed to the internal structure 6.

The inverter being closed, the rod 24 is substantially vertical. During the retreat of the hoods 10 controlled by the cylinders 14, the rod 24 drives the flaps 8 in a rotational movement around their front joints 20, which closes the annular vein 4. The fresh air flow is directed to the outside through the grids 12 which are fully out of the front frame 2, to be returned partly forward to deliver a braking thrust.

Cylinders 14 are obtained which do not fit into the frame 16 of the movable covers 10, which makes it possible to provide a circular frame which is substantially continuous, giving the best rigidity with a reduced mass.

Cylinders 14 are also obtained arranged under the grids 12, which do not fit into the circular ring formed by these grids, which avoids making certain specific grids containing recesses for housing these jacks, which would reduce the aerodynamic efficiency of these jacks. grids for thrust reversal.

With the thrust reverser closed, the flaps 8 comprise at the front a boss facing radially outwardly 28, comprising a front sealing surface provided with an elastomer, resting on the inside wall 34 of the front frame. 2, below slots 32 made on this wall for the movement of the cylinders 14 during their deployments.

In this way with the succession of flaps 8, a complete circular seal is obtained which closes the radially outer surface of the fresh air flow 4, in particular the slots 32, in order to prevent outward losses in direct flow, and to improve the performance. Figures 3 and 4 show the inner wall 34 of the front frame 2, having a substantially straight portion forming the radially outer surface of the air flow 4 when the inverter is closed, then backward a curved portion facing the outside, forming the aerodynamic channel for guiding the air flow when opening the inverter.

The structure of the inner wall 34 may be acoustic, comprising a honeycomb partition having a surface having bores. The realization of this inner wall 34 is simplified because it undergoes only aerodynamic forces, and does not participate in the structure of the assembly, no body being fixed on it.

The front frame 2 comprises at the front hooks 40 arranged radially inward and facing the axis of the nacelle, for fixing the complete inverter on the structure of the nacelle located upstream. The hooks 40 supporting the fittings 30 receiving the rear attachment of the cylinders 14, can form circular sectors that simplify manufacturing and reduce costs. The inner wall 34 is fixed on these hooks 40 in a simple manner, allowing rapid disassembly.

The front frame 2 has a transverse upstream partition 42, which can be completely sealed to serve as fire protection with the compartment in front. This upstream partition 42 supports the outer panel of the front frame 2.

Note that the box 18 of the front frame 2 is easily accessible after removal of the outer wall, having opened the inverter, which provides access to the control system of the inverter located in without opening the hood of the structure arranged upstream. This saves time for maintenance, with greater safety because no large and extensive structure, such as the fan cowl, is located upstream of the inverter which must be opened to access the control system of the inverter placed in upstream of the front frame, can be carried away by the wind during these operations.

In other words, access to the control system of the thrust reverser is achieved through a hatch located in the outer part of the box. The box 18 of the front frame 2 allows to implement a locking system of the movable cowl 10 disposed just upstream of the cowl, at the rear of the box, which can act directly on a fitting of the mobile cowl, or indirectly on connecting parts of the movable hood.

An example of the locking system 44 presented, fixed to the rear of the box 18, comprises a folding cam which is directly engage in a corresponding hollow of a reinforced element of a grid 12, when the inverter is fully closed .

FIGS. 5 and 6 show a second locking system making it possible not to stress the structure of the box 18, comprising an inclined lever 50 having in front of a fastener similar to that of the jack 14, fixed directly on the hook 40 now the complete inverter on the platform. The front end of this lever 50 tilted by a control jack 52, includes a hook 52 engaging on a fastener 54 of the movable cowl 10, which holds the cowl in the closed position. Similarly, the system shown in FIGS. 3 and 4 can be connected by a specific fitting directly to the hook 40.

This locking system defers the locking forces of the inverter on the upstream structure of the front frame 2, which avoids soliciting the box 18, and allows to lighten it.

In general, the locking system is advantageously placed in an angular position offset from the control cylinders 14, so as not to receive debris turbine blades in case of bursting if these cylinders are themselves same affected by these debris, to maintain a maintenance of the inverter in the closed position.

FIGS. 7 and 8 show, in a variant, means for opening the shutters 8, enabled by the upstream fixed structure comprising the box 18 elongated towards the rear, comprising a long link 60 integrated when the inverter is closed, in a longitudinal groove performed on the surface of the inner wall 34. In this way the long link 60 does not interfere with the aerodynamic flow 4 in direct flow. The rear end of the rod 60 is linked by a hinge 64 to the rear of a flap 8, its front end being connected by a hinge 66 to a fitting directly connected to the hook 40 attached to the upstream part of the nacelle. This applies the significant forces from the air pressure on the flaps 8, directly on a frame of the upstream part, without soliciting the thrust reverser.

This opening means requires a rod 60 sufficiently long giving a large radius of deflection, to obtain an inverted jet angle "a" between the surface of the flap 8 and the direction perpendicular to the inner surface 6 of the annular vein, which is less than 30 ° so as to obtain a good aerodynamic performance for this jet.

Note that the rod 60 still working in traction, can be carried out in a thin and light manner with a suitable structure and material. Moreover when the inverter is open, the long link 60 forming a reduced angle with the longitudinal direction, exerted by the hook 40 a substantially longitudinal traction on the upstream structure which is reinforced, which is favorable for the transmission of forces and the holding the inverter.

When the inverter opens, the rear end of the flap 8 comes to a small distance "h" from the inner surface 6 of the annular vein, which varies at the end of opening because of the curvature of this internal surface, and the longitudinal displacement towards the rear of the articulation of this shutter 20 fixed to the mobile frame 16. This distance "h" is necessary to avoid contacts in all cases of operation, taking into account manufacturing dispersions and deformations during operation.

If this distance "h" is estimated to be too great, by causing a high leakage rate for the inverted jet, an elastomer pad 62 can be added to a rear boss of the flaps 8 facing the inner surface 6 of the annular vein when the inverter is open, which comes into contact with this inner surface when these flaps are deployed.

FIG. 9 shows a fitting 30 fixed flat on a ferrule 74 comprising a front hook 76 for holding on the front structure, by screws passing through the bores 78. The fitting 30 comprises a longitudinal groove 72 forming a yoke, for receiving the end of a jack 14 or a long rod 60 for controlling the movable covers 10 or flaps 8, which is fixed by a transverse axis providing a joint. The transverse axis passes into a bore 80 which opens on each side in a recess 82 of the fitting 30, to engage this axis.

In general, an inverter is obtained with movable covers 10 which may have a reduced thickness, the grids 12 and the flaps 8 with their control systems, being deported upstream of these covers. This inverter can be lighter and more rigid. Aerodynamic profiles are optimized, fuel consumption is reduced.

Claims

1. Thrust reverser of a turbojet engine nacelle, comprising movable covers (10) which recoil with respect to a front frame (2) under the effect of jacks (14) by driving by means of rods (24, 60) the tilting of flaps (8) initially folded inside these covers, to substantially close the annular cold air duct (4), and by opening grids (12) arranged around this vein which receive the air flow cold to return it to the front, characterized in that the rear end of the grids (12) and the cylinders (14) are fixed upstream of the movable covers (10) and slide with them, these grids and cylinders being entered into a box (18) of the front frame (2) when the inverter is closed, and in that said cylinders (14) have a front end disposed radially inwardly of said box (18).

2. thrust reverser according to claim 1, characterized in that when the inverter is closed, the cylinders (14) are arranged radially below the grids (12).

3. thrust reverser according to claim 1, comprising at least one control system disposed within said box, characterized in that the access to said control system is achieved through at least one hatch located at an outer portion of said box (18).

4. thrust reverser according to one of claims 2 or 3, characterized in that the box (18) has an inner wall (34) comprising a rearward curved portion facing outwards, forming an aerodynamic channel allowing guiding the air flow when opening the inverter.

5. thrust reverser according to claim 4, characterized in that the curved portion of the inner wall (34) has slots (32) for the passage of the cylinders (14), the flaps (8) comprising at the front a sealing surface (28) bearing on this inner wall below the slots when the inverter is closed.

6. Thrust reverser according to any one of the preceding claims, characterized in that the front frame (2) is attached to the upstream structure by hooks (40) arranged radially inwardly of the frame, for fixing the complete inverter on the structure of the nacelle located upstream.

7. thrust reverser according to claim 6, characterized in that the rear end of the cylinders (14) is fixed to the front frame (2) on a fitting (30) disposed near the hooks (40).

8. thrust reverser according to claim 7 characterized in that the box (18) comprises a locking system of the movable cowl, comprising at least one lever (50), a downstream end is integral with said cowl and an upstream end is secured to the front frame, said upstream end being fixed on said fitting (30).

A thrust reverser according to any one of the preceding claims, characterized in that each flap (8) has a front hinge (20) attached to the front of the movable hoods (10), and a rear hinge (22) attached. at the rear end of a control rod (24) comprising its front end (26) attached to the inner surface (6) of the annular vein.

10. thrust reverser according to any one of claims 1 to 7 characterized in that each flap (8) comprises a long rod (60) integrated when the inverter is closed, in a longitudinal groove formed on the surface of the wall interior (34) of the box (18), its rear end being connected by a hinge (64) to the rear of this flap, its front end being connected by a hinge (66) to the front structure (2).

1 1. Thrust reverser according to claims 6 and 10, characterized in that the front end of the long rod (60) is connected to the front frame (2) by a fitting (30) disposed near the hooks (40).

A thrust reverser according to any one of the preceding claims, characterized in that the trailing end of the flaps (8) comprises an elastomeric pad (62) engaging the inner surface (6) of the annular vein when these components are deployed.

13. Turbojet engine nacelle comprising a thrust reverser, characterized in that the inverter is made according to any one of the preceding claims.