Thrust reverser comprising a deployable deflection grid, and having a design that reduces its axial size
The thrust reverser with a deployable deflection grid and connecting follower mechanism addresses the issue of increased axial length and mass by offsetting the downstream fin assembly, enhancing performance and reducing drag and fuel consumption.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN NACELLES
- Filing Date
- 2025-11-25
- Publication Date
- 2026-06-04
AI Technical Summary
Existing thrust reversers with deployable deflection grids have an increased axial length and mass, leading to higher drag and specific fuel consumption due to the presence of deflection grids within the propulsion system, which constraints the axial space and increases the overall mass of the inverter components.
A thrust reverser design featuring a deployable deflection grid with a connecting follower mechanism that allows the downstream fin assembly to be axially offset during thrust reversal, reducing the axial footprint in the direct thrust configuration and enhancing performance by adjusting the grid's position.
The design achieves reduced drag and specific fuel consumption while maintaining a compact axial footprint, improving aircraft performance and reducing environmental impact by minimizing the length of the reverser and its components.
Smart Images
Figure FR2025051102_04062026_PF_FP_ABST
Abstract
Description
[0001] 51526 AP 1
[0002] Thrust reverser including a deployable deflection grid, and featuring a design that reduces its axial footprint
[0003] technical field
[0004] The invention relates to the field of nacelles and thrust reversers for aircraft propulsion systems, and, more particularly, to thrust reversers equipped with deployable deflection grids to generate flow reversal.
[0005] Prior art
[0006] Thrust reversers are devices that divert the airflow through the propulsion system forward, in order to shorten landing distances and limit the stress on the brakes on the landing gear.
[0007] The grid-type reversers currently used in the aeronautical sector include deflection grids integrated into a fixed or movable reverser structure. The movable reverser structure comprises one or more movable reverser hoods and is mounted to be transversally articulated relative to the fixed structure between a forward position for direct thrust and a rearward position for thrust reversal.
[0008] In the thrust reverser position, to divert at least part of the secondary flow towards the grilles, the reverser is usually equipped with shutters which, when deployed, at least partially block the secondary flow. This forces the secondary flow air radially outwards towards the grilles, which then generate the forward counter-thrust airflow.
[0009] The flaps are generally pivotally mounted on the radially inner wall of the reversing valve covers, this wall defining the secondary jet radially outwards. Recesses are therefore provided in this radially inner wall of the reversing valve covers to accommodate the shut-off flaps in the retracted position, as adopted in direct jet operation.
[0010] In prior art, it has already been proposed to replace the flaps with one or more deployable membranes for obturating the secondary vein. Such a design is, for example, known from document FR 3 076 864 Al. 51526 AP 2
[0011] While the presence of deployable sealing membranes in the secondary flow helps to limit the overall mass of the reversing turbine, this mass is still affected by the presence of the deflection grids. These grids incorporate fins / vanes designed to direct the flow forward to achieve the counter-thrust function. The deflection grids are arranged inside the reversing turbine in a direct thrust configuration, which creates an axial space constraint for housing these grids.
[0012] An increase in the axial length of the deflection grids generates an increase in the length of several inverter components, such as the inverter's movable hood(s), actuators, etc. This inevitably leads to a greater inverter mass as well as greater drag, resulting in increased specific fuel consumption.
[0013] To address this issue, it is possible to design deployable deflection grids, meaning those with a smaller axial footprint in direct thrust configuration than in thrust reversal configuration. This could be a telescopic deflection grid, as described, for example, in document FR 2 947869 Al.
[0014] However, there remains a need to improve the performance of the inverter, while keeping it as compact as possible in direct thrust configuration, in the axial direction.
[0015] Description of the invention
[0016] To meet at least partially the need mentioned above, the invention first relates to a thrust reverser for an aircraft propulsion system, the reverser comprising a fixed structure and a movable structure comprising at least one movable reverser hood equipped with a radially internal reverser hood wall, the movable structure being translationally movable relative to the fixed structure along a longitudinal central axis of the reverser, between an advanced direct thrust position and a rearward thrust reversal position, the thrust reverser also comprising a deployable deflection grid comprising several axially successive fin assemblies, the grid being capable of adopting a folded inactive position as well as a deployed active position in which the fin assemblies are further apart axially from each other than in the folded inactive position,the reversing unit comprising a front grid support frame belonging to the fixed structure, and a rear grid support element fixed to the movable cover, the grid in the folded inactive position being arranged at least partially in a housing open axially upstream, at an upstream end of the reversing unit cover when the movable structure is in its forward direct thrust position.
[0017] According to the invention, the reverser comprises a connecting follower between the rear grid support element and the most downstream fin assembly of the grid, the connecting follower being mounted movable relative to the most downstream fin assembly so as to adopt a retracted position when the movable structure occupies its forward direct thrust position, as well as an axial offset position of the grid when the movable structure occupies its rearward thrust reversal position, in which the most downstream fin assembly is further axially offset from the rear grid support element than in the forward direct thrust position.
[0018] The invention advantageously provides that the downstream fin assembly of the grid is positioned further away from the rear grid support element in the thrust reversal position. This feature, made possible by the specific arrangement of the connecting follower between the downstream fin assembly and the rear grid support element, ensures higher reversing performance while maintaining a reduced axial footprint in the direct thrust configuration. Indeed, the reversing performance is enhanced by the axial offset of the downstream fin assembly, which can therefore be axially displaced from the movable cowling upstream in the thrust reversal configuration. In other words, the invention allows for a simple and reliable adjustment of the axial position of the deployed grid in the thrust reversal configuration.
[0019] Furthermore, the retractable nature of the connecting follower element allows for a compact grid in the direct thrust configuration, and consequently ensures a reduced length of the reverser mounted in the nacelle. Drag is therefore reduced, as is specific fuel consumption. The invention is thus the result of technological research aimed at significantly improving aircraft performance and, in this respect, contributes to reducing the environmental impact of aircraft (decarbonization).
[0020] The invention preferably provides for at least one of the following optional technical features, taken individually or in combination.
[0021] Preferably, the connecting follower is mounted to slide relative to the downstream fin assembly of the grid. Other relative movements could nevertheless be provided between these elements, in order to ensure the passage of the connecting follower from its retracted position to its axially offset position of the grid, without departing from the scope of the invention.
[0022] Preferably, the rear grid support element is a fitting, or a rear grid support frame delimiting downstream the housing of the movable cover.
[0023] Preferably, the movable reversing hood is equipped with a radially external wall, defining with the radially internal wall of the reversing hood the axially open housing, at the upstream end of the reversing hood.
[0024] Preferably, in the rearward thrust reversal position of the moving structure, an axial distance of grid offset, defined between the rear grid support element and the most downstream fin assembly, corresponds to at least 50% of an axial distance between the rear grid support element and an upstream end of the radially external wall of the moving hood.
[0025] Preferably, each fin assembly of the grid comprises a flow deflection fin, as well as means for supporting this fin. Preferably, these support means for the fin assemblies form one or more telescopic follower arms. Other deployment designs for the deflection grid are nevertheless possible without departing from the scope of the invention. In particular, it is possible to consider rail systems between the fin assemblies, or even retaining elements between them using flexible elements, for example, textile elements and / or cables. 51526 AP 5
[0026] Preferably, the connecting follower element forms a downstream end of one of the telescopic follower arms, while remaining therefore without a flow deflection fin.
[0027] Preferably, the reversing device comprises an actuator passing internally through the connecting follower. However, the actuator could alternatively be offset circumferentially and / or radially from the connecting follower, without departing from the scope of the invention.
[0028] Finally, the invention also relates to an aircraft propulsion system comprising such a reverser.
[0029] Other advantages and features of the invention will appear in the detailed, non-limiting description below.
[0030] Brief description of the drawings
[0031] The detailed description that follows refers to the attached drawings on which:
[0032] [Fig. 1] is a schematic half-view in longitudinal section of a propulsion assembly, including a thrust reverser shown in direct thrust configuration; [Fig. 2] is a half-view in longitudinal section of the reverser equipping the propulsion assembly shown in Figure 1, with the reverser shown in direct thrust configuration;
[0033] [Fig. 3] is a longitudinal half-section view similar to that of Figure 2, with the reverser shown in a thrust reversing configuration;
[0034] [Fig. 4] is a more detailed perspective view of the reverser in the form of a preferred embodiment of the invention, and shown in a direct thrust configuration;
[0035] [Fig. 5] is a schematic longitudinal cross-sectional view of one of the inverter deflection grids shown in the previous figure, the grid being shown in the folded inactive position;
[0036] [Fig. 6] is a perspective view similar to that of Figure 4, with the reverser shown in thrust reversing configuration; 51526 AP 6
[0037] [Fig. 7] is a view similar to that of figure 5, with the grid shown in the active deployed position.
[0038] Detailed description of implementation methods
[0039] Figure 1 shows a propulsion assembly 1 of an aircraft, presenting a longitudinal central axis Al.
[0040] Subsequently, the terms "upstream" and "downstream" are defined relative to a general SI sense of gas flow through the propulsion assembly 1, along the axis Al when this assembly generates direct thrust. The terms "upstream" and "downstream" could respectively be substituted by the terms "front" and "rear," with the same meaning.
[0041] The propulsion unit 1 includes a turbomachine 2, a nacelle 3 and a mast (not shown), intended to connect the propulsion unit 1 to a wing (not shown) of the aircraft.
[0042] The turbomachine 2 in this example is a twin-spool, turbofan engine comprising, from front to rear, a fan 5, a low-pressure compressor 6, a high-pressure compressor 7, a combustion chamber 8, a high-pressure turbine 9, and a low-pressure turbine 10. The compressors 6 and 7, the combustion chamber 8, and the turbines 9 and 10 form a gas generator. The turbofan engine 2 has a fan casing 11 connected to the gas generator by structural arms 12.
[0043] The nacelle 3 comprises a front section forming an air inlet 13, a middle section which includes two blower hoods 14 enveloping the blower housing 11, and a rear section 15.
[0044] During operation, an airflow 20 enters the propulsion assembly 1 through the air inlet 13, passes through the blower 5, and then splits into a primary flow 20A and a secondary flow 20B. The primary flow 20A flows into a primary gas circulation channel 21A that passes through the gas generator. The secondary flow 20B flows into a secondary channel 21B surrounding the gas generator. The secondary channel 21B is radially delimited inwardly by a fixed internal shroud that encloses the gas generator. In this example, the fixed internal fairing comprises a first section 17 belonging to the middle section 14, and a second section 18 extending rearward from the first section 17, so as to form part of the rear section 15. This second section 18 is an integral part of a fixed structure of a thrust reverser which will be described below.This same section will subsequently be called wall 18 of radially internal delimitation of the secondary vein 21B, or internal wall 18.
[0045] Radially outwards, the secondary stream 21B is delimited by the fan housing 11 and, in the configuration of Figure 1, by one or more movable reversing gear covers 33 forming part of the rear section 15 of the nacelle 3, which will be described later. More specifically, between the fan housing 11 and the reversing gear covers 33, there is an outer ring 40 of an intermediate housing 42, the latter comprising the aforementioned structural arms 12, the radially external end of which is fixed to this ring 40. This ring therefore also contributes to delimiting the secondary stream 21B radially outwards, being located in the downstream axial extension of the fan housing 11.
[0046] The nacelle 3 therefore includes a thrust reverser 30 (shown schematically and partially in Figure 1), centered on the axis Al and comprising, on the one hand, a fixed structure 31 attached to the fan casing 11, and on the other hand, a structure 29 movable relative to the fixed structure 31. The fixed structure 31 includes, for example, a front frame 46, onto which is attached a streamlined aerodynamic part called the deflection edge 46B, which guides the flow of the reversed jet. This front frame 46 allows the connection with the fan casing 11, in a known manner.
[0047] The reversing unit also includes several deployable deflection grids 32, one of which is schematically shown in a folded, inactive position in Figure 1. The grids 32 are arranged in a circumferential direction. They are deployable, also called "extendable," which allows them to have a smaller axial footprint in the folded, inactive position than in the deployed, activated position shown in Figure 3, thus enabling them to perform the thrust reversal function. 51526 AP 8
[0048] Furthermore, the mobile structure 29 comprises the aforementioned movable reversing unit hoods 33, for example, two hoods 33 each extending over an angular range of approximately 180°. This configuration with two hoods 33 is particularly well-suited to a nacelle design in which the hoods / walls 18 are also hinged, the reversing unit 30 then exhibiting a so-called "D-duct" architecture. In this architecture, the hoods 18 and 33 are connected in such a way as to open and close simultaneously during engine maintenance. However, other architectures are possible, such as a "C-duct" architecture or an "O-duct" architecture.
[0049] Each reversing gear cowl 33 comprises a radially external wall 50 forming an external aerodynamic nacelle surface, and a radially internal wall 52 contributing to the outward delimitation of the secondary duct 21B. This wall 52 lies in the downstream continuity of the deflection edge 46B in the direct thrust configuration. The two walls 50 and 52 define a housing 54 open axially at the upstream end of the reversing gear cowl 33, in which at least a portion of each grid 32 is located in the folded, inactive position in the reversing gear's direct thrust configuration.
[0050] Figure 1 schematically shows the reverser 30 in a forward thrust configuration, known as "direct jet," corresponding to a standard flight configuration. In this configuration, the cowls 33 of the movable structure 29 are in a closed position, known as the forward thrust or "direct jet" position, in which these reverser cowls 33 rest on the fixed structure 31. Indeed, in the direct thrust configuration, the upstream end 52A of the radially internal wall 52 of each cowl 33 rests axially against a box section of the forward frame, with the deflection edge 46B arranged radially inwards.
[0051] The movable structure 29 is thus translationally movable relative to the fixed structure 31 along the axis Al of the reverser, between the forward direct thrust position shown in Figure 1 (51526 AP 9), and a rearward thrust reversal position which will be described later. In the forward direct thrust position of the movable structure 29, each grid 32, in its folded inactive position, is arranged at least partially within the housing 54 of the reverser covers 33, being isolated from the secondary stream 21B by the radially internal wall 52 of these sliding covers 33. This wall 52, forming the external wall of the secondary stream, is also called the internal acoustic panel.
[0052] The principle of the invention is schematically represented in Figures 2 and 3, with the mobile structure 29 shown in the forward direct thrust position in Figure 2, and in the rearward thrust reversal position in Figure 3. In addition, one of the grids 32 is shown in the inactive folded position in Figure 2, and in the active deployed position in Figure 3.
[0053] Figure 3 shows that the deflection edge 46B and the upstream end of the movable hood 33 axially define, on the secondary flow 21B, a radial extraction opening 56 for at least a portion 20B' of the secondary flow 20B. This opening 56 of the secondary flow 21B is thus delimited upstream by the deflection edge 46B. Conventionally, this edge flares radially outwards towards the rear, to define an airflow 20B' intended to pass through this opening 56 when the movable structure is in this rearward thrust reversal position. In other words, the deflection edge 46B, here made rigidly, has a shape that gradually moves away from the axis Al from front to back, to guide / deflect the air through the opening 56 and towards the grids 32, in thrust reversal configuration.On the contrary, this opening 56 of the secondary vein 21B is notably delimited downstream by the upstream end 52A of the radially internal part 52 of the hood 33.
[0054] In order to force at least a part 20B' of the secondary flow 20B towards the opening 56, the inverter 30 includes one or more closing elements 58. These may be rigid closing elements, such as flaps, and / or flexible closing membranes, of a deployable nature.
[0055] In the schematic diagrams of Figures 2 and 3, the shutter flaps 58 are of conventional design, namely that they are pressed against the wall 52 of the movable hood 33 in the direct thrust configuration, and tilted radially into the secondary jet in the thrust reversal configuration. The kinematics of the flaps 58's movement are also known, particularly with regard to connecting rods 62 articulated on the inner wall 18.
[0056] As mentioned previously, several deployable grids 32 are preferentially arranged in succession within the inverter along the circumferential direction. These grids 32 can all be identical and arranged in the same way, so as to generate a counter-thrust flux 20B" with a forward axial component. Consequently, the design and operation will subsequently be described for only one of the grids 32.
[0057] For the support of the deflection grid 32, the inverter also includes a rear grid support frame 60 and a front grid support frame 70, each extending in the circumferential direction. The front support frame 70 is integrated into the fixed structure 31 of the inverter, while the rear support frame 60 is integrated into the movable structure 29. The front frame 70 is preferably located in or near a forward axial end of the opening 56, while the rear frame 60 connects the two walls 50, 52 of the movable hood 33, delimiting downstream the housing 54. It is noted that the rear frame 60 could be replaced by another rear grid support element, such as a fitting, fixed internally to one and / or the other of the two walls 50, 52 of the movable hood.
[0058] The deployable deflection grid 32 is therefore fixed on these two support frames 60, 70, which are preferably designed to support several adjacent grids 32 in the circumferential direction, or even to support all the grids of the same hood, over an angular sector close to 180°.
[0059] The grid 32 comprises several finned assemblies 32a, which are arranged axially in succession. As will be described below in a preferred embodiment of the invention, each finned assembly 32a comprises at least one flow deflection fin, of conventional and rigid design, as well as means for supporting the fin. The axially arranged assemblies 32a within the reconstituted grid define a downstream fin assembly, referenced 32a', and opposite it, a more upstream fin assembly, referenced 32a". The more upstream fin assembly 32a" is fixed directly to the front frame 70, while the more downstream fin assembly 32a' is fixed indirectly to the rear frame 60, via a connecting follower element 72, which will be described later.
[0060] The number of fin assemblies 32a within the grid can vary, and is typically between three and fifteen assemblies, each comprising a fin extending continuously along the entire circumferential length of the grid 32, or one that can be interrupted in the same direction. In the schematic views of Figures 2 and 3, only the fins of these assemblies 32a are shown, and not their support means.
[0061] In the active position shown in Figure 3, the fin assemblies 32a are further apart axially than in the inactive position shown in Figure 2, where these assemblies 32a are nested within each other to reduce the overall axial bulk. In this folded inactive position, at least several of these fin assemblies 32 are therefore arranged in the housing 54 of the hood, the open upstream end of which is delimited between the upstream ends 50A, 52A of the walls 50, 52 of the hood 33. Also in this folded inactive position of the grid 32, occupied when the hood 33 is in its forward direct thrust position, the most downstream fin assembly 32a' is preferentially in axial contact with the rear frame 60, or in close proximity to it.
[0062] One of the distinctive features of the invention lies in the presence of the connecting follower 72, which connects the rear frame 60 to the downstream fin assembly 32a' of the grid 32. More precisely, the follower 72, shown schematically only in Figures 2 and 3, is mounted to move relative to the downstream fin assembly 32a'. Thus, it can adopt a retracted position when the movable structure 29 is in its forward direct thrust position, as well as an axially offset position of the grid when the movable structure 29 is in its rearward thrust reversal position. In this latter position, the downstream fin assembly 32a' is further axially offset from the rear frame 60 than in the forward direct thrust position. 51526 AP 12
[0063] Indeed, in its retracted position, the follower ni overlaps axially with several of the finned assemblies 32a of the grid 32, for example with more than a majority of these assemblies 32a, and for example with all or almost all of them. To achieve this, the follower 72 can pass through these finned assemblies 32a.
[0064] The connecting follower 72 is preferably mounted to slide relative to the downstream fin assembly 32a' of the grid, for example, by sliding on the latter in the same direction as the direction in which the grid 32 unfolds / extends. Preferably, this follower 72 serves as a motion transmission element for the deployment of the grid 32 when the inverter is opened. Indeed, when the cover 33 moves rearward, it carries with it the follower 72, which is fixed to the rear frame 60 integrated into this cover. Also, preferably, the beginning of the movement of the cover 33 marks the sliding of the follower 72 relative to the fin assemblies of the grid 32, until this follower 72 reaches an axial stop on the downstream fin assembly 32a'.It is this first part of the movement of the hood 33 that causes the follower 72 to move from its retracted position to its axially offset position of the grille. The continuation of the rearward movement of the hood 33 causes the grille 32 to deploy / extend, which is axially stressed by the follower 72, via the most downstream fin assembly 32a'.
[0065] This design allows, in thrust reversal configuration, for at least some of the finned assemblies 32a located furthest downstream of the grid to be extracted from outside the housing 54. Thanks to this axial adjustment of the grid 32 relative to the extraction opening 56, the relevant assemblies 32a can thus actively participate in the thrust reversal function, and contribute advantageously to increasing the performance of the reverser.
[0066] In the rearward thrust reversal position of the moving structure shown in Figure 3, an axial offset distance of the grid, referenced "Dad", is observed, defined axially between the rear frame 60 and the most downstream fin assembly 32a'. This is therefore the upstream offset distance of the grid 32 from the rear frame 60. In addition, an axial distance, referenced "Da", is observed between the rear frame 60 and the upstream end 50A of the radially external wall 50 of the movable hood 33. Preferably, the reverser is designed so that the distance Dad corresponds to at least 50% of the distance Da, and even more preferably to at least 70% of this distance Da, the latter also being sufficient to cover the folded grid in the direct thrust configuration.
[0067] Finally, although not described, it is noted that several connecting follower elements 72 could be associated with each grid 32, preferably spaced circumferentially from one another. For example, two elements 72 could be fitted to each deflection grid 32, located respectively near the two circumferential ends of the grid in question. Furthermore, conventionally, the inverter includes one or more actuators to generate the movement of the movable structure 29. These actuators (not shown in Figures 1 to 3) can be connected to the movable hood 33, for example, to the rear frame 60 of this hood, or to one of its walls 50, 52.
[0068] During operation, after the inverter opens, the secondary flow 20B passes through the secondary channel 21B and encounters, at least partially, the shutter flaps 58. These flaps force a portion 20B' of this flow through the opening 56, and thus through the grids 32, which are brought into the deployed active position as described above. The flow of this portion 20B' between the fins of the grids 32 causes the air to be axially straightened, thereby generating the counter-thrust flow 20B''. Furthermore, it should be noted that the inverter is also closed by actuators, which produce events identical or similar to those described above for opening, but in reverse order.
[0069] Figures 4 to 7 show a preferred embodiment of the invention, in which each fin assembly 32a of the grid comprises a rigid flow deflection fin 74a and support means 76a for this fin. More specifically, the support means for the fin assemblies 32a form one or more telescopic follower arms 82, preferably two arms 82. To this end, each fin assembly 32a therefore includes a section 76a of each arm 82. Furthermore, two follower elements of the type described above, respectively form the downstream ends of the two telescopic follower arms 82, as downstream end sections of these arms, conventionally fixed to the rear frame 60.
[0070] These downstream end sections of the telescopic follower arms 82, lacking deflection vanes 74a, constitute the connecting follower elements 72, ensuring the upstream displacement of the grid 32 in the thrust reversal configuration. Within each arm 82, the axial stop 84 between each follower element 72 and the most downstream vane assembly 32a' is achieved in a conventional manner, such as that encountered between any two adjacent sections of a telescopic arm. This design provides simplicity of operation and manufacture.
[0071] Figure 4 shows an actuator 80 of the reverser, mounted at one end on the front frame 70, and at the other end on one and / or the other of the walls 50, 52 of the movable cover 33, downstream of the rear frame 60. It therefore comprises a first part of the actuator 80a fixed on the front frame 70 or on another element of the fixed structure of the reverser, and a second part of the actuator 80b fixed on the movable cover, for example downstream of the rear frame 60. To do this, the actuator 80 passes through the rear frame 60, which is provided with an opening for this purpose. But preferably, as has been schematically shown in figures 5 to 7, at least one actuator 80 of the inverter passes internally through the support means 76a of the fins, that is to say, passes internally through one of the telescopic arms 82, as well as its downstream end section forming the follower member 72.This arrangement can be adopted for each of the two arms 82, or for only one of them. A coaxial arrangement of the elements 80 and 82 is preferred. In this case, the inverter actuator 80 can be of any type, and preferably a worm gear drive.
[0072] The downstream end of the actuator 80 can be fixed downstream of the rear frame 60 by passing through the latter, or, as shown in figures 5 to 7, be fixed on the same rear frame 60. In this case, at least a portion of the first part of the actuator 80a can 51526 AP 15 be located in an upstream area with respect to the inverter and the front frame 70, called the blower area.
[0073] Various modifications can be made by a person skilled in the art to the invention described above, solely by way of non-limiting examples, the scope of which is defined by the appended claims. For example, the thrust reverser 30 can alternatively have a "C" or "O" configuration. Furthermore, all the features disclosed above, in the various preferred embodiments and their alternatives, are combinable. Moreover, it should be noted that in all the figures described above, elements bearing the same numerical references correspond to identical or similar elements.
Claims
51526 AP 16 DEMANDS 1. Thrust reverser (30) for an aircraft propulsion system, the reverser comprising a fixed structure (31) and a movable structure (29) comprising at least one movable reverser cowl (33) equipped with a radially internal reverser cowl wall (52), the movable structure being translationally movable relative to the fixed structure along a longitudinal central axis (Al1) of the reverser, between a forward direct thrust position and a rearward thrust reverser position, the thrust reverser also comprising a deployable deflection grid (32) comprising several axially successive fin assemblies (32a), the grid being capable of adopting a folded inactive position as well as a deployed active position in which the fin assemblies (32a) are further axially separated from each other than in the folded inactive position, the reverser comprising a forward grid support frame (70) belonging to the fixed structure (31),as well as a rear grid support element (60) fixed to the movable cover (33), the grid in the folded inactive position being arranged at least in part in a housing (54) open axially upstream, at an upstream end of the reversing cover (33) when the movable structure (29) is in its forward direct thrust position, characterized in that it comprises a follower element (72) for connecting the rear grid support element (60) and the downstream fin assembly (32a') of the grid, the follower element (72) being movable relative to the downstream fin assembly (32a') so as to adopt a retracted position when the movable structure (29) is in its forward direct thrust position, and an axially offset position of the grid when the movable structure (29) is in its rearward thrust reversing position,in which the most downstream fin assembly (32a') is located further axially from the rear grid support element (60) than in the forward direct thrust position.
2. Inverter according to claim 1, characterized in that the connecting follower member (72) is mounted sliding relative to the most downstream finned assembly (32a') of the grid (32). 51526 AP 17 3. Inverter according to claim 1 or 2, characterized in that the rear grid support element (60) is a fitting, or a rear grid support frame delimiting downstream the housing (54) of the movable cover (33).
4. Inverter according to any one of the dependent claims, characterized in that the movable inverter cover (33) is equipped with a radially external wall (50), defining with the radially internal wall of the inverter cover (52) the axially open housing (54) at the upstream end of the inverter cover (33).
5. Inverter according to claim 4, characterized in that in the rearward thrust reversal position of the moving structure, an axial offset distance (Dad) of the grid (32), defined between the rear grid support element (60) and the most downstream fin assembly (32a'), corresponds to at least 50% of an axial distance (Da) between the rear grid support element (60), and an upstream end (50A) of the radially external wall (50) of the movable hood (33).
6. Inverter according to any one of the dependent claims, characterized in that each fin assembly (32a) of the grid (32) comprises a flow deflection fin (74a), as well as support means (76a) for this fin.
7. Inverter according to claim 6, characterized in that the support means (76a) of the finned assemblies (32a) form one or more telescopic follower arms (82).
8. Inverter according to claim 7, characterized in that the connecting follower member (72) forms a downstream end of one of the telescopic follower arms (82).
9. Inverter according to any one of the preceding claims, characterized in that it comprises an actuator (80) passing internally through the connecting follower member (72).
10. Aircraft propulsion assembly (1) comprising a reverser (30) according to any one of the preceding claims.