EP4111045A1

EP4111045A1 - Front frame and cascade of a thrust reverser of an aircraft nacelle

Info

Publication number: EP4111045A1
Application number: EP21708287.4A
Authority: EP
Inventors: Xavier Cazuc; Vincent Jean-François Peyron; Jean-Philippe Joret; Sébastien Laurent Marie PASCAL
Original assignee: Safran Nacelles SAS
Current assignee: Safran Nacelles SAS
Priority date: 2020-02-26
Filing date: 2021-02-16
Publication date: 2023-01-04
Also published as: US20230088298A1; FR3107568B1; CN115176080A; WO2021170934A1; FR3107568A1

Abstract

The invention relates to an assembly (601) which comprises a front frame (602) of a thrust reverser structure of an aircraft nacelle and at least one cascade (603). The assembly is characterized in that, when the cascade is fixed to the frame, the axial distance (L) that separates the first blading (605) upstream of the cascade from a covering area (606) between the extension of the cascade and the front frame is greater than or equal to once the mean height (h) of the cascade.

Description

DESCRIPTION

TITLE: FRONT FRAME AND DEVIATION GRID OF A THRUST INVERTER OF A

AIRCRAFT NACELLE

Technical field of the invention

The invention relates to the field of aircraft turbojet nacelles. In particular to the thrust reversal systems which equip these nacelles and more specifically to an assembly comprising a front frame and a plurality of deflection grids for such a thrust reversal system.

Technical background

The state of the art includes in particular documents US-A-4,177,639, RU-C1-2 145,672 and EP-A1-1 176 302.

Thrust reverser systems or thrust reversers are now widely used in aircraft nacelles and, in particular, in nacelles which house a bypass turbojet. In a known manner, such a turbojet engine generates, by means of the blades of a rotating fan, a flow of hot air (called primary flow) coming from a combustion chamber, and a flow of cold air (called secondary flow) which circulates outside the turbojet through an annular channel formed between a shroud of the turbojet engine and an internal wall of the nacelle. The two air streams are then ejected out of the turbojet from the rear of the nacelle and thus generate a thrust.

In such a configuration, the role of a thrust reverser is, during a landing phase of the aircraft, to improve its braking capacity on the ground by redirecting at least part of the thrust forward. generated by the turbojet. In particular, when the thrust reverser is in action, it obstructs the annular channel of the cold air flow (ie the secondary flow) and directs this flow towards the front of the nacelle, thereby generating a counter thrust . The means implemented to achieve this reorientation of the cold air flow vary according to the type of inverter. However, in all cases, the structure of a thrust reverser comprises movable cowls movable between, on the one hand, a deployed position (also called thrust reversal position) in which they open in the nacelle a passage intended to the deflected flow, and on the other hand, a retraction position (also called direct jet position) in which they close this passage. The cowls can thus fulfill a function of activating other deflection means such as shutters. In this case, the flaps, actuated by the movement of the movable cowl, obstruct, at least in part, the channel in which the secondary flow circulates. In addition, in the case of a thrust reverser called deflection grilles, the reorientation of the air flow is then effected by deflection grids.

FIG. 1 schematically illustrates part of an aircraft nacelle 101 which comprises a thrust reverser 111 according to the prior art in the thrust reversal position. The circulation of the air flow is symbolized by the arrow 109 and the terms upstream and downstream are used below with reference to this direction of flow of the flow.

The inverter 101 comprises at least one movable cowl 102 relative to the fixed structure 103 of the internal duct, called IFS for “Inner Fixed Structure”. The cover 102 has an outer wall 104 and an inner wall 105 which define, in a direct jet position of the turbojet (not shown), an outer wall of the annular channel 106 in which the secondary flow flows. The reverser further comprises at least one flap 107 mounted in an articulated manner on the movable cover 102. At least one actuator, such as for example a jack (not shown) slides the movable cover 102 and causes the sealing of the annular channel. 106 by the shutter (s) 107. This shutter 107 deflects at least part of the secondary flow out of said annular channel 106 towards deflection grids 110, thus generating the counter-thrust.

The reorientation of the secondary flow can thus be carried out by the deflection grids 110 depending on whether they are covered or uncovered by translation of the movable cowl along the axis X around which the nacelle extends. The deflection grids 110 are further disposed adjacent to each other in an area annular surrounding the annular channel 106 and comprise series of blades 115 which extend from upstream to downstream.

The zone 112 corresponds to the junction zone between a fixed structure called the front frame 113, a deflection grid 110 and a deflection edge 114 of the thrust reverser 111. This junction zone is illustrated in more detail in FIG. 2. .

In the known state of the art, the deflection grids 110 are attached to the turbojet casing via a front frame 113. An element called the deflection edge 114, also attached to the front frame, makes it possible to form a aerodynamic line and to direct the air flow towards the deflection grilles 110 as illustrated by the arrow 201. In the example shown, the most downstream portion 203 of the front frame 113 is used to allow the attachment of both of the deflection grids 110 and of the deflection edge 114. In addition, the deflection edge 114 has a curvature 205 which forms a cavity 204 in which are housed fixing means (not shown). The deflection grids, the front frame and the deflection edge are thus fixed together by common fixing means located at the level of this cavity and near the first upstream blades 202 of the deflection grids upstream of said blades.

Thus, as illustrated in FIG. 2, in the known state of the art, the fixing of the various elements which constitute a thrust reverser is based in particular on the existence of an axial excess length of the front frame relative to the length 206. The expression “over-length” is used here by comparison with a length less than or equal to a threshold value 206 which would make it possible in particular to simplify the manufacturing process of the front frame by making its dimensions compatible with manufacturing by simple machining from a single block of material. In other words, the extra length imposes a more complex and more expensive manufacture of the front frame.

Summary of the invention

The present invention proposes a solution making it possible to limit the dimensions of the front frame on which the deflection grids are fixed so as to make possible the manufacture of said front frame by a simple and economical manufacturing method. In addition, the invention makes it possible to maintain aerodynamic performance of the thrust reverser at least equivalent to those of a state-of-the-art reverser.

To this end, according to a first aspect, the invention relates to an assembly comprising a front frame of a thrust reverser structure of an aircraft nacelle and at least one deflection grid, said assembly being annular and s' extending around an axis, said deflection grid comprising, upstream, a grid extension, extending radially and / or axially relative to the axis of the assembly, intended to allow the fixing of said grid on said frame front, said assembly being characterized in that, when the deflection grille is fixed to the frame, the axial distance separating a first upstream vane of said deflection grille and an overlap zone between the grille extension and the front frame is greater than or equal to once an average height of the deflection grid.

The assembly according to the invention can comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

- The assembly further comprises a deflection edge fixed to the front frame and configured to direct a flow of gas towards the deflection grid.

the deflection edge has a curvature adapted so that one end of said deflection edge is superimposed with the front frame when the deflection edge is fixed to said front frame.

- The deflection grid is fixed to the front frame, by fixing means, located in the overlap zone between the grille extension and the front frame.

- the deflection grid is fixed to the deflection edge by first fixing means and said deflection edge is fixed, at its end closest to the deflection grid, to the front frame by second fixing means different from those of first means of fixing.

- the deflection grid, the deflection edge and the front frame are fixed to each other by common fixing means located in the overlap zone between the grille extension and the front frame. - The front frame further comprises an angle, adapted to allow the attachment of the deflection edge and the deflection grid to the front frame.

- The angle iron is fixed to the deflection edge by first fixing means and in which the deflection grid is fixed to the front frame by second fixing means.

- the grid extension of the deflection grid further comprises a profile, adapted to allow the fixing of the deflection grid to the deflection edge and to the front frame and, when the deflection grid is fixed to the front frame, the axial distance separating a first upstream vane of said deflection grid and a zone of overlap between the profile and the front frame is greater than or equal to once an average height of the deflection grid.

- The profile is fixed to the deflection edge by first fixing means and is fixed to the front frame by second fixing means.

- The fixing means used to fix the deflection grid and / or the deflection edge and / or the angle iron to the front frame are of the countersunk head and nut cages or screw and nut cages type.

Brief description of the figures

The present invention will be better understood and other details, characteristics and advantages of the present invention will emerge more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which:

[Fig. 1] FIG. 1 is a schematic view, in longitudinal section, of a thrust reverser according to the prior art in the thrust reversal position;

[Fig. 2] FIG. 2 is a schematic view, in longitudinal section, of the junction zone between a front frame, a deflection grid and a deflection edge of a thrust reverser according to the prior art;

[Fig. 3] FIG. 3 is a schematic view, in longitudinal section, of the junction zone between a front frame, a deflection grid and a deflection edge of a thrust reverser according to a first embodiment of the invention; [Fig. 4] FIG. 4 is a schematic view, in longitudinal section, illustrating means for fixing a deflection grid and / or a deflection edge to a front frame of a thrust reverser according to embodiments of invention;

[Fig. 5] FIG. 5 is a perspective view schematically illustrating the manufacture by machining, from a single plate of a determined material, of a front frame according to the invention;

[Fig. 6] FIG. 6 is a schematic view, in longitudinal section, of the junction zone between a front frame, a deflection grid and a deflection edge of a thrust reverser according to a second embodiment of the invention;

[Fig. 7] FIG. 7 is a schematic view, in longitudinal section, of the junction zone between a front frame, a deflection grid and a deflection edge of a thrust reverser according to a third embodiment of the invention;

[Fig. 8] FIG. 8 is a schematic view, in longitudinal section, of the junction zone between a front frame, a deflection grid and a deflection edge of a thrust reverser according to a fourth embodiment of the invention; and,

[Fig. 9] FIG. 9 is a schematic view, in longitudinal section, of the junction zone between a front frame, a deflection grid and a deflection edge of a thrust reverser according to a fifth embodiment of the invention.

The elements having the same functions in the different embodiments have the same references in the figures.

Detailed description of the invention

With reference to FIG. 3, we will now describe a first embodiment of the invention. The assembly according to the invention can be integrated into any type of aircraft nacelle comprising a thrust reverser such as, for example, that described above with reference to FIG. 1.

The assembly 601 comprises a front frame 602 of a thrust reverser structure of an aircraft nacelle and at least one deflection grid 603. The assembly 601 is annular and extends around the X axis. The axial and radial terms used below are therefore understood to be relative to this axis. Those skilled in the art will appreciate that such annular assembly can, in particular embodiments, comprise deflection grids which are not disposed on a continuous angular sector of 360 degrees. For example, spaces may be formed between two adjacent deflection grids or certain angular sectors may not include grids. The deflection grid 603 comprises, upstream, in the direction of flow of the gases, a grid extension 604. The grid extension 604 corresponds to an elongated portion of the deflection grid 603 which extends axially. This extension is intended to allow the grille to be attached to the front frame. In addition, the extension makes it possible not to modify the position of the first upstream vane 605, in the vein in which the flow circulates (in the thrust reversal position), with respect to an assembly in which the front frame would extend. more downstream axially. In other words, the upstream extension of the grid compensates for the shortening of the front frame compared to a front frame of the state of the art.

More precisely, as it appears more clearly, in FIG. 6, in all the embodiments of the invention, when the deflection grid 603 is fixed to the front frame, the axial distance L which separates the first upstream vane 605 from the deflection grid and an overlap area 606 between the gate extension and the front frame is greater than or equal to once an average height h of the deflection gate. In particular, the axial distance L is delimited, on the one hand, upstream, by the most downstream axial station of the front frame and, on the other hand, downstream by the most upstream axial station of one foot of a first channel of the deflection grid. The average height h is for its part defined as being the average, over the entire surface of the grid, of the radial distance (illustrated by the arrow in FIG. 6) between the lower face 603a and the upper face 603b of the grid. Further, the height h of the grid can vary over the surface of the grid and the average can be measured in an axial and / or circumferential direction of the grid.

The expression “overlap zone” designates the zone in which the elements concerned - in this case the grille extension and the front frame - are superimposed either directly or by means of a third element. Those skilled in the art will appreciate that, in Figures 3, 6, 7, 8 and 9 showing different embodiments of the assembly according to the invention, the means for fixing the different elements of the assembly are not shown but their position is symbolically represented by solid lines crossing the elements attached to each other.

In addition, FIG. 4 presents non-limiting examples of fixing means used to fix a deflection grid and / or a deflection edge and / or an angle (as will be described later) to the front frame. In the figure, the fixing means 401 shown in the left part of the figure are of the countersunk head and nut cages type while the fixing means 402 shown on the right part of the figure are of the screw and nut cages 402 type. , the latter make it possible to transmit to the frame before the forces undergone by the deflection edge.

In the example corresponding to the embodiment described with reference to FIG. 3, the overlap zone is the zone where the gate extension 604 presents an interface with a portion 609 of a deflection edge 607 which itself presents an interface with a portion 610 of the front frame.

Indeed, in particular embodiments of the assembly, the latter further comprises a deflection edge which is fixed to the front frame and configured to direct the flow of gas towards the deflection grid. In the example shown in FIG. 3, in the thrust reversal position, the flow follows the path symbolized by arrow 611.

Furthermore, the deflection edge 607 comprises, in its portion which extends axially downstream of the front frame, a curvature 608 (also called return) which is adapted so that the end (the portion) 609 of the deflection edge meets. overlaps with portion 610 of the front frame. Advantageously, the portion of the deflection edge which extends axially downstream of the front frame contributes to an improvement in the aerodynamic continuity of the assembly from the point of view of the flow which circulates therein.

Finally, the grille extension makes it possible to fix the grille on a front frame shorter than a front frame of the state of the art. Therefore, as shown in Fig. 5, a front frame angular sector (intended to be joined with other sectors to form a complete frame) can be, for example, manufactured in one piece. machined from a single block (plate) of a specific material. For example, aluminum 7040. In particular, it is no longer necessary to assemble two distinct elements in the axial direction to manufacture this angular sector of the front frame. In the example shown in FIG. 3, the deflection grid , the deflection edge and the front frame are secured together by common fastening means located in the overlap area between the grille extension and the front frame. Figures 6, 7, 8 and 9 show variants in which the fixing of the different elements to each other is done differently. Figures 6 and 7 show embodiments of the assembly comprising a front frame, a deflection grid and a deflection edge in which the deflection grid is directly attached to the front frame, by first fixing means located in the overlap area between the grid extension and the front frame and the deflection edge is fixed to the front frame, at its end closest to the deflection grid, by second fixing means different from the first fixing means .

Further, in the embodiment of Figure 6, the gate extension extends axially upstream of the gate while in the embodiment shown in Figure 7, the gate extension extends radially and , therefore, the portion of the front frame to which it attaches as well. Those skilled in the art will know how to adjust these particular arrangements to specific manufacturing, robustness and / or size constraints.

It should be noted that, in the various embodiments of the assembly, the curvature

608 of the deflection edge 607 may be larger or smaller so that the end

609 of said deflection edge forms a return upstream or extends radially in its portion intended to be fixed to the front frame. Further, in the embodiment described with reference to Figure 3, the curvature 608 allows the end 609 to extend axially to extend upstream and interact with the grille extension and the front frame. to secure these three elements together. On the other hand, in the embodiments described with reference to Figures 6, 7, 8 and 9, the curvature 608 implies that the end 609 of the deflection edge is of radial extension to allow attachment to an inner radial extension of the frame. before (ie in figures 6 and 7), or a insert (ie in figures 8 and 9). Here again, those skilled in the art will know how to adjust the shape of the deflection edge and the shape of the portion of the front frame facing each other in response to constraints, for example, of specific manufacturing and / or aerodynamics.

In the embodiment presented with reference to FIG. 8, the front frame further comprises an angle iron which is adapted to allow the attachment of the deflection edge and of the deflection grid to the front frame. This angle can itself be fixed to the rest of the front frame by fixing means common to those used to fix the deflection grid or different from these.

In the example shown in FIG. 8, the angle bar 801 is fixed to the deflection edge by first fixing means and the deflection grid is fixed to the front frame by second fixing means. Thus, in this particular case, the fixing of the deflection grid on the front frame is carried out at the level of the overlap zone 606 between the grid extension 604, the part 602 and the angle bar 801 of the front frame. Advantageously, the use of such an angle can allow, on the one hand, the reduction of the axial dimension of the front frame, and consequently, its simplified manufacture by machining a single block of material and, on the other hand , the use of deflection grids not requiring any modification compared to those of the state of the art.

In the embodiment shown with reference to Fig. 9, the grille extension of the deflection grid further comprises a profile which is adapted to allow attachment of the deflection grid to the deflection edge and to the front frame.

In the example shown, the profile 901 is fixed to the deflection edge by first fixing means and it is fixed to the front frame by second fixing means. In other words, the deflection grid 603 is not directly fixed to the part 602 of the front frame but is fixed to the latter, by means of the profile 901. Thus, in this particular case, the fixing of the deflection grid on the front frame is produced at the level of the overlap zone 606 between the profile 901 and the front frame. Advantageously, the use of such a profile can make it possible, on the one hand, to reduce the axial dimension of the front frame, and therefore, its simplified manufacture by machining of a single block of material and, on the other hand, the use of deflection grids which do not require modification from those of the state of the art.

Claims

1. Assembly (601) comprising a front frame (602) of a thrust reverser structure of an aircraft nacelle and at least one deflection grid (603), said assembly being annular and extending around it. 'an axis (X), said deflection grid comprising, upstream, a grid extension (604), extending radially and / or axially relative to the axis (X) of the assembly, intended to allow fixing of said grid on said front frame, said assembly being characterized in that, when the deflection grid is fixed to the frame, the axial distance (L) separating a first upstream vane (605) of said deflection grid and a zone of overlap (606) between the gate extension and the front frame is greater than or equal to once an average height (h) of the deflection gate.

2. The assembly of claim 1, further comprising a deflection edge (607) attached to the front frame and configured to direct a flow of gas toward the deflection grid.

3. An assembly (601) according to claim 2, wherein the deflection edge (607) has a curvature (608) adapted so that one end (609) of said deflection edge overlaps with the front frame (602) when the. deflection edge is attached to said front frame.

4. An assembly (601) according to any one of claims 1 to 3, wherein the deflection grid (603) is fixed to the front frame (602), by fixing means (401, 402), located in the area. cover (606) between the grille extension and the front frame.

5. An assembly (601) according to claim 2 or claim 3, wherein the deflection grid (603) is fixed to the deflection edge (607) by first fixing means and said deflection edge is fixed, at the level of its end closest to the deflection grid, to the front frame by second fixing means different from the first fixing means.

6. An assembly (601) according to claim 2 or claim 3, wherein the deflection grid (603), the deflection edge (607) and the front frame (602) are fixed to each other by fixing means. common located in the overlap area between the grille extension and the front frame.

7. The assembly (601) of claim 2 or claim 3, wherein the front frame further comprises an angle (801), adapted to allow the attachment of the deflection edge (607) and the deflection grid (603) to the front frame (602) and, when the deflection grid (603) is fixed to the frame (602), the axial distance (L) separating a first upstream blade (605) of said deflection grid and an overlap zone ( 606) between the grid extension and said angle iron is greater than or equal to once an average height (h) of the deflection grid.

8. The assembly (601) of claim 7, wherein the angle iron (801) is fixed to the deflection edge (607) by first fixing means and wherein the deflection grid (603) is fixed to the front frame ( 602) by second fixing means.

9. An assembly (601) according to claim 2 or claim 3, wherein the grille extension of the deflection grid (603) further comprises a profile (901), adapted to allow attachment of the deflection grid ( 603) to the deflection edge (607) and to the front frame (602) and, when the deflection grid (603) is attached to the front frame (602), the axial distance (L) separating a first upstream vane (605) of said deflection grid (603) and an overlap zone (606) between the profile (901) and the front frame (602) is greater than or equal to once an average height (h) of the deflection grid.

10. The assembly (601) of claim 9, wherein the profile (901) is fixed to the deflection edge (607) by first fixing means and wherein the profile (901) is fixed to the front frame (602) by second fixing means.

11. Thrust reverser of an aircraft nacelle comprising an assembly according to any one of claims 1 to 10.