Turbine jet engine rear portion comprising a nozzle with a flap having a lever movable by upstream and downstream support walls

Abstract

A rear section for a turbojet engine includes a variable geometry nozzle in which a converging flap is provided with a lever (80) supporting a support roller (96) axially arranged between an upstream support wall (90) and a downstream support wall (92), the upstream and downstream support walls being rigidly fixed to a movable section capable of axial movement relative to an upstream stator structure (38) upon command, such that the support roller moves freely in the radial direction (R) relative to the upstream and downstream support walls. During downstream movement of the movable section, the upstream support wall pushes the lever to pivot the downstream end (46) of the converging flap toward the longitudinal axis. Therefore, the operation of the drive mechanism for moving the movable section can be optimized while limiting the size and mass of the device used to control the flap.

Description

Technical Field

[0001] This invention relates to the field of variable geometry nozzles for turbojet engines used to propel aircraft. Background Technology

[0002] Turbojet engines used for supersonic flight typically include an afterburner passage, the exit of which is defined by a variable geometry axisymmetric nozzle. That is, the variable geometry axisymmetric nozzle can adapt its geometry to the different speeds that the aircraft may fly at.

[0003] To this end, such a nozzle includes at least one set of movable inner flaps (referred to as converging flaps) distributed around the longitudinal axis of the turbojet engine, and each movable inner flap has an upstream end hinged to an internal structure of the housing. Each of the converging flaps includes a panel for guiding the exhaust airflow within the nozzle. The nozzle also includes a system for controlling the converging flaps, which enables the converging flaps to pivot synchronously around a hinge axis at the housing.

[0004] Typically, nozzles used for supersonic flight also include another set of movable inner flaps (referred to as diverging flaps), distributed around the longitudinal axis. Each movable inner flap includes a panel designed to guide the exhaust airflow within the nozzle, and each movable inner flap has a corresponding upstream end hinged to the downstream end of a converging flap. Thus, this type of nozzle is called a converging-diverging nozzle. In this case, the control system is also configured to servo-control the position of the diverging flaps relative to the position of the converging flaps. Therefore, this system allows for continuous variation of the respective tilt angles of the converging flaps relative to the longitudinal axis of the turbojet engine, and the tilt angle of the corresponding diverging flaps relative to that axis, according to defined, explicit rules. Therefore, in particular, this nozzle allows for variation of the position and shape of the nozzle throat.

[0005] It should be noted that the qualifier "gradually expanding" does not preclude the flaps from being oriented parallel to the longitudinal axis, or even converging during certain phases of operation. Similarly, particularly in cases where the nozzle does not include a gradually expanding flap, the converging flap may be oriented parallel to the longitudinal axis, or even gradually expanding during certain phases of operation.

[0006] In this case, a variable geometry nozzle is required, which is effective in the radial direction and saves space so that the system for controlling the movable inner flap can be integrated into a limited space. Summary of the Invention

[0007] This invention is specifically designed to meet this need in a simple, economical and effective manner.

[0008] Therefore, the present invention provides a rear section of a turbojet engine, the rear section of which includes:

[0009] -Upstream stator structure;

[0010] - A variable geometry nozzle comprising a set of converging flaps distributed around a longitudinal axis of the rear portion of a turbojet engine, each converging flap including a panel designed to guide exhaust airflow within the nozzle, and each converging flap having an upstream end hinged to an upstream stator structure along a corresponding first hinge axis; wherein at least some of the converging flaps, referred to as controlled converging flaps, each include a lever rigidly fixed to a corresponding panel and extending in a direction away from the longitudinal axis, the lever carrying a support roller rotatably mounted on the lever along an axis parallel to the corresponding first hinge axis; and

[0011] - A drive unit, comprising a movable portion capable of axially moving relative to the upstream stator structure according to instructions.

[0012] The support rollers of the lever of at least one of the controlled convergent flaps are axially arranged between an upstream support wall and a downstream support wall, which are rigidly fixed to a movable part of the drive unit, such that the support rollers of the lever are free to move relative to the upstream and downstream support walls, at least in the radial direction relative to the longitudinal axis.

[0013] Therefore, as the movable part of the drive unit moves downstream, the upstream support wall pushes the lever downstream, causing the convergent flap to pivot along the corresponding first hinge axis, resulting in the downstream end of the convergent flap being closer to the longitudinal axis.

[0014] Furthermore, during the upstream movement of the movable part of the drive unit, at least if the turbojet engine stops, the downstream support wall pushes the lever upstream, causing the convergent flap to pivot along the corresponding first hinge axis, resulting in the downstream end of the convergent flap moving away from the longitudinal axis.

[0015] Therefore, the drive mechanism can be utilized optimally during enhanced control of the converging flaps of the nozzle. Furthermore, the device implemented for controlling the flaps can thus have optimally limited size and mass.

[0016] In an embodiment of the invention, one of the upstream support wall and the downstream support wall is connected to a movable part of the drive device via the other of the upstream support wall and the downstream support wall.

[0017] In an embodiment of the invention, the outer connecting wall connects the respective radially outer ends of the upstream support wall and the downstream support wall to each other.

[0018] In an embodiment of the invention, an upstream support wall arranged opposite to the support roller of each lever and an upstream support wall arranged opposite to the support roller of the two closest levers are circumferentially spaced apart, and a downstream support wall arranged opposite to the support roller of each lever and a downstream support wall arranged opposite to the support roller of the two closest levers are circumferentially spaced apart, thereby forming an annular row of support devices, each support device including one upstream support wall and one downstream support wall.

[0019] In an embodiment of the invention, the rear portion of the turbojet engine includes a synchronizing ring surrounding the set of convergent flaps or upstream stator structure, and each support device in the support assembly is connected to a movable portion of the drive unit via the synchronizing ring.

[0020] In an embodiment of the present invention, for each support device, a first connecting sidewall connects the corresponding first circumferential ends of the upstream support wall and the downstream support wall to each other, and a second connecting sidewall connects the corresponding second circumferential ends of the upstream support wall and the downstream support wall to each other, with the second circumferential ends opposite to the first circumferential ends.

[0021] In an embodiment of the invention, the variable geometry nozzle further includes a set of expanding flaps distributed around a longitudinal axis, the set of expanding flaps including a panel designed to guide the exhaust airflow within the nozzle, and the set of expanding flaps having an upstream end hinged to the downstream end of the expanding flaps, thereby making the nozzle a converging-expanding nozzle.

[0022] A turbojet engine for an aircraft, comprising the rear portion of the type described above. Attached Figure Description

[0023] The invention will be better understood by reading the following description, given by way of non-limiting example, and with reference to the accompanying drawings, and other details, features, and advantages of the invention will become apparent, as illustrated in the drawings:

[0024] - Figure 1 This is a schematic half-view of an axial section of a turbojet engine, including nozzles with variable geometry.

[0025] Figure 2 is a schematic half-view of the rear section of a turbojet engine of a known type;

[0026] - Figure 3 According to an embodiment of the present invention, Figure 1A schematic half-view of the rear section of a turbojet engine;

[0027] - Figure 4 It constitutes Figure 1 A schematic perspective view of some components of the rear section of a turbojet engine;

[0028] - Figure 5 and Figure 6 yes Figure 4 An enlarged schematic perspective view of a portion of the visible elements.

[0029] In all these figures, the same reference numerals may denote the same or similar elements. Detailed Implementation

[0030] Figure 1 A turbojet engine 10, such as a twin-shaft ducted turbojet engine, is shown for propelling a supersonic aircraft, specifically designed for installation within the fuselage of such an aircraft. The invention is, of course, applicable to other types of turbojet engines.

[0031] In this specification, the axial direction X is the direction of the longitudinal axis 11 of the turbojet engine. Unless otherwise stated, the radial direction R is the direction orthogonal to and passing through the longitudinal axis 11 at all points, and the circumferential direction C is the direction orthogonal to both the radial direction R and the longitudinal axis 11 at all points. Unless otherwise stated, the terms "inner" and "outer" refer to the relative proximity and relative distance of an element from the longitudinal axis 11, respectively. Finally, the qualifiers "upstream" and "downstream" are defined with reference to the approximate direction D of gas flow in the turbojet engine 10.

[0032] By way of example, this turbojet engine 10 includes, from upstream to downstream, an air inlet 12, a low-pressure compressor 14, a high-pressure compressor 16, a combustion chamber 18, a high-pressure turbine 20, a low-pressure turbine 22, an afterburner passage 26, and a variable geometry nozzle 28, such as a converging-diverging variable geometry nozzle. These components of the turbojet engine are centered along the longitudinal axis 11 of the turbojet engine.

[0033] In a known manner, the high-pressure compressor 16, combustion chamber 18, and high-pressure turbine 20 and low-pressure turbine 22 define a primary flow path PF. This primary flow path is surrounded by a secondary flow path SF of the turbine, which extends downstream from the outlet of the low-pressure compressor. Thus, during operation, air F1 enters through air inlet 12 and is compressed by the low-pressure compressor 14, then is split into a main flow F2 flowing in the primary flow path and a secondary flow F3 flowing in the secondary flow path. The main flow F2 is then further compressed in the high-pressure compressor 16, subsequently mixed with fuel and ignited in the combustion chamber 18, and then expanded in the high-pressure turbine 20 and subsequently in the low-pressure turbine 22.

[0034] Then, the exhaust gas flow F4 flows through the afterburner passage 26 and is then discharged from the turbojet engine 10 through the nozzle 28. The exhaust gas flow consists of a mixture of combustion gases from the main flow path and secondary flow F3.

[0035] In an operating mode with afterburning, which propels the aircraft, for example, at supersonic speeds, fuel is mixed with exhaust gas F4 in afterburning channel 26, and the resulting mixture is ignited in the afterburning channel to generate additional thrust.

[0036] Figure 2 shows the rear section of a turbojet engine in a configuration known in the prior art at a larger scale, and in particular, the movable inner flaps of the nozzle are visible.

[0037] The movable inner flap consists of a set of converging flaps distributed around the longitudinal axis 11 at the upstream end, and a set of gradually expanding flaps 32 also distributed around the longitudinal axis 11 at the downstream end.

[0038] Each of these movable inner flaps includes panels 31 and 33, which externally define an exhaust gas flow passage 34, which is defined by extending the afterburner passage 26. Therefore, the movable inner flaps 30 and 32 enable the guide of exhaust gas flow F4 at the outlet of the turbojet engine 10 during operation.

[0039] The converging flap 30 is hinged at its upstream end 36 to the stator structure 38 of the rear part of the turbojet engine, in this case to the inner yoke 40 of the beam portion 42 belonging to the stator structure, so that the converging flap 30 can rotate about a first hinge axis A1 fixed to the stator structure 38.

[0040] The expanding flap 32 is hinged at its upstream end 44 to the downstream end 46 of the converging flap 30, allowing the expanding flap 32 to rotate about a second hinge axis A2 fixed to the converging flap 30. The expanding flap 32 is also hinged at its downstream end 48 to the first end 50A of the connecting rod 50, which has an opposing second end 50B that is hinged to the stator structure 38, in this case to the outer yoke 54 of the beam portion 42.

[0041] A system for controlling a movable inner flap includes a drive mechanism configured to act on at least some of the converging flaps (hereinafter referred to as controlled converging flaps). Where other converging flaps are acted upon by the drive mechanism solely through the controlled converging flaps, these other converging flaps are known to be referred to as following converging flaps.

[0042] The drive unit typically consists of cylinders 56, each cylinder having a stationary portion (e.g., cylinder body 56A) and a movable portion (e.g., cylinder rod 56B). The stationary portion is fastened to the stator structure 38, and the movable portion is fixed to a corresponding roller support 58. Rollers 60 are mounted on the roller support, and the rollers contact a protrusion 62 in a rolling bearing manner. The protrusion is formed by a structure 64 fixed to a panel 31 of a corresponding converging flap. The roller support 58 is also fixed to a retaining finger 66, which engages with the structure 64 to radially retain the converging flap 30 and, in particular, prevent the flap from descending under gravity when the turbojet engine stops. Thus, this set of movable inner flaps 30 and 32, together with the stator structure 38, forms a balancing system.

[0043] Therefore, the translational movement of the movable portion of each cylinder 56 enables the converging flap 30 to rotate about the first hinge axis A1, which is accompanied by the rotational movement of the diverging flap 32 about the second hinge axis A2. This displacement of the movable inner flaps 30, 32 results in a change in the nozzle profile, particularly altering the cross-section of the nozzle throat at the junction between the converging and diverging flaps.

[0044] The nozzle also includes a movable outer flap 70 having an upstream end 72 and a downstream end 74, the upstream end being hinged to the stator structure 38 (e.g., hinged to the outer yoke 54 of the beam 42), and the downstream end being fixed to the downstream end 48 of the expanding flap 32, for example, by a connection of rollers 76 and sliding parts 78.

[0045] The variable geometry configuration of nozzle 28 allows the nozzle to adapt to different flight phases. Thus, in subsonic mode, the converging inner flap 15 remains in a weakly converging configuration, while in supersonic mode, the converging inner flap adopts a strong converging configuration.

[0046] The disadvantage of the above-described control system is that during the operation that increases the convergence of the converging flap, the cylinder 56 operates in the retraction direction of the cylinder rod 56B, which is the least efficient direction of operation, and this type of operation requires the greatest force.

[0047] Other known control systems do not include rollers or convex parts, but rather consist of a series of elements hinged to each other. In these systems, the portion of the cylinder connected to the stator structure is hinged to the stator structure about an orthogonal (i.e., tangential) axis. Therefore, a disadvantage of such control systems is their relatively large size in the radial direction.

[0048] Now refer to Figures 3 to 6 A more detailed description of an embodiment of the present invention Figure 1 The rear section of the turbojet engine.

[0049] Each of the controlled convergence flaps 30 includes a lever 80, which is fixed to the flap panel 31. This lever 80 extends naturally from the panel 31 or, in the example shown, from a reinforcing structure 81 in a direction away from the longitudinal axis 11, which is arranged on the outer surface of the panel 31 and fixed to the panel.

[0050] Similar to the description above, the rear section of the turbojet engine includes a drive unit comprising a movable portion capable of axial movement relative to the upstream stator structure 38 upon command. By way of example, the drive unit here is also constituted by a cylinder 56, with the cylinder's rod 56B forming the movable portion.

[0051] In order for the movable part of the drive device to act on the lever 80 of at least one of the controlled convergence flaps 30, the lever 80 is axially arranged between the upstream support wall 90 and the downstream support wall 92, which are rigidly fixed to the movable part of the drive device, such that the lever 80 is free to move relative to the upstream support wall 90 and the downstream support wall 92 at least in the radial direction R relative to the longitudinal axis 11.

[0052] In this way, as the movable part of the drive unit (composed of rod 56B) moves downstream, the upstream support wall 90 pushes the lever 80 downstream, causing the convergent flap 30 to pivot along the corresponding first hinge axis A1, resulting in the downstream end 46 of the flap being brought closer to the longitudinal axis 11.

[0053] Conversely, during the upstream movement of the movable portion of the drive unit, at least if the turbojet engine stops, the downstream support wall 92 pushes the lever 80 upstream, causing the converging flap 30 to pivot along the corresponding first hinge axis A1, resulting in the downstream end 46 of the flap moving away from the longitudinal axis 11. If the turbojet engine is running, even before the downstream support wall 92 contacts the lever 80, the thrust of the gas on the converging flap 30 is sufficient to cause the converging flap to pivot. Therefore, advantageously, the upstream support wall 90 has increased rigidity compared to the downstream support wall 92. For this purpose, the upstream support wall 90 can be thicker than the downstream support wall 92, or the upstream support wall 90 can have reinforcing ribs, while the downstream support wall 92 may not have such reinforcing ribs.

[0054] The lever 80 is provided with a cylindrical rotating body-shaped support roller 96, which is rotatably mounted on the lever 80 along an axis 94 parallel to the corresponding first hinge axis A1, and is arranged between the upstream support wall 90 and the downstream support wall 92, such that any contact between either the upstream support wall 90 or the downstream support wall 92 on the lever 80 is a cylindrical / planar contact.

[0055] Therefore, during the pivoting operation of the converging flap, the radial movement of the support roller 96 relative to the relevant support wall is achieved by the rolling of the support roller 96 on the support wall under the thrust applied to the support roller 96 by one of the upstream support wall 90 and the downstream support wall 92.

[0056] The axial distance between the upstream support wall 90 and the downstream support wall 92 is greater than the diameter of the support roller 96, so that an axial gap permanently exists between the support roller 96 and the support wall opposite to the support wall on which the thrust is applied.

[0057] The support roller 96 is advantageously arranged at the free end of the lever 80 to maximize the lever arm applied to the associated convergent flap 30 by the upstream support wall 90 and the downstream support wall 92.

[0058] Therefore, the support roller 96 is, for example, mounted on an axis supported by two side arms 80A, 80B, which form the end fork of the lever 80. Figure 5 ).

[0059] Furthermore, one of the support walls in the support arm (the downstream support wall 92 in this case) is connected to the movable part of the drive unit via another support wall (the upstream support wall 90 in this case).

[0060] Therefore, the outer connecting wall 98 connects the corresponding radially outer ends of the upstream support wall 90 and the downstream support wall 92. Figures 3 to 6 They are interconnected.

[0061] Preferably, the above description relating to the manipulation of the lever of one of the controlled convergence flaps also applies to the other controlled convergence flaps.

[0062] Therefore, in the illustrated embodiment, the upstream support wall 90 arranged opposite to each lever 80 and the upstream support wall 90 arranged opposite to the two levers 80 closest to the lever under consideration are circumferentially spaced apart, and the downstream support wall 92 arranged opposite to each lever 80 and the downstream support wall 92 arranged opposite to the two levers 80 closest to the lever under consideration are circumferentially spaced apart. Figure 4 Therefore, the upstream support wall 90 and the downstream support wall 92 form an annular row of support devices 100 spaced apart from each other, each support device 100 including a corresponding pair of support walls, the corresponding pair of support walls including one upstream support wall of the upstream support wall 90 and one downstream support wall of the downstream support wall 92.

[0063] The rear portion of the turbojet engine shown also includes a synchro ring 82, which is arranged around the set of convergent flaps 30, or alternatively around the upstream stator structure 38 slightly upstream, and each support in the support assembly 100 is connected via the synchro ring to a movable part of the drive unit, namely the set of rods 56B connected to the cylinder 56.

[0064] Specifically, the movable portion of the drive unit is connected to the synchronizing ring 82 to enable the synchronizing ring to translate along the longitudinal axis 11. For this purpose, the rod 56B of the cylinder 56 is hinged to the first yoke 84 of the synchronizing ring 82. This first yoke 84 is formed to protrude from the body 86 of the synchronizing ring 82, for example, having a toroidal shape. The first yoke 84 extends, for example, upstream from the body 86.

[0065] It should be noted that the body 86 of the synchronizing ring can have a more complex shape, including, for example, alternations of radially inward and radially outward projecting portions and / or alternations of upstream and downstream projecting portions. In all cases, the body 86 of the synchronizing ring extends around the longitudinal axis 11 of the turbojet engine and thus has a generally annular shape.

[0066] Each support in the support assembly 100 is connected to the synchronizing ring 82, for example, by three arms 102, the three arms being circumferentially spaced from each other, and each of the three arms connecting the synchronizing ring 82 to the downstream support wall 92. Figure 4 ).

[0067] Alternatively, control of the converging flap 30 can be ensured directly by a movable part of the drive unit (e.g., via the cylinder rod 56B) without using a synchronizing ring.

[0068] In the example shown, within each support device 100 (one of the support devices is in...) Figure 5 As can be seen in the image, the first connecting sidewall 104 connects the respective first circumferential ends of the upstream support wall 90 and the downstream support wall 92 to each other, and the second connecting sidewall 106 connects the respective second circumferential ends of the upstream support wall 90 and the downstream support wall 92 to each other, with the second circumferential ends opposite to the first circumferential ends. Therefore, the first connecting sidewall 104 and the second connecting sidewall 106 enable the upstream support wall 90 to be connected to the downstream support wall 92, and thus enable the upstream support wall to be connected to the synchronization ring 82, and connected to the movable part of the drive unit via the synchronization ring.

[0069] In this case, the external connecting wall 98 can of course be omitted.

[0070] During operation, the deployment of the rod 56B of each cylinder 56, or more generally, the downstream deployment of the movable portion of the drive mechanism, causes the synchronizing ring 82 to move downstream, which drives each upstream support wall 90 and each downstream support wall 92 downstream. This brings each upstream support wall 90 into contact with the support roller 96 of the corresponding lever 80. Each upstream support wall 90 then pushes the support roller 96 downstream and thus the lever 80, causing the corresponding flap to pivot in the direction of the longitudinal axis 11, which enhances the convergence of the convergent flap 30. During flap pivoting, the support roller 96 rolls on the upstream support wall 90, a rolling motion permitted by the gap between the roller 96 and the other support wall (in this case, the downstream support wall 92).

[0071] Conversely, the retraction of the rod 56B of each cylinder 56, or more generally, the retraction of the movable portion of the drive mechanism upstream, causes the synchronizing ring 82 to move upstream, which drives each upstream support wall 90 and each downstream support wall 92 upstream. If the turbojet engine stops, this brings each downstream support wall 92 into contact with the support roller 96 of the corresponding lever 80. Each downstream support wall 92 then pushes the support roller 96 upstream and thus the lever 80, causing the corresponding flap to pivot in the opposite direction to the longitudinal axis 11, which reduces the convergence of the converging flap 30. During flap pivoting, the support roller 96 rolls on the downstream support wall 92, a rolling motion permitted by the gap between the roller 96 and the other support wall (in this case, the upstream support wall 90). However, if the turbojet engine is running, even before the downstream support wall 92 contacts the lever 80, the thrust of the gas on the converging flap 30 can be sufficient to cause the converging flap to pivot.

[0072] Therefore, during operation, cylinder 56 operates in the deployment direction of cylinder rod 56B to enhance the convergence of the converging flaps, which is advantageous from a mechanical point of view. In fact, at least in the preferred case where cylinder 56 is a hydraulic cylinder, the deployment of the rod is due to hydraulic pressure applied across the entire surface of the piston, while the retraction of the rod is due to hydraulic pressure applied to the piston surface due to the reduced cross-section of the rod. At least for this reason, the deployment of the rod relative to its retraction generally provides increased power.

[0073] Furthermore, all components involved in the control of the inner flap (including lever 80, upstream support wall 90 and downstream support wall 92, and the means of connecting the upstream support wall and downstream support wall to the movable part of the drive unit) can therefore have limited size and mass.

[0074] Furthermore, advantageously, the lever 80 of each of the controlled convergence flaps 30 is arranged at the upstream end 30A of the flap to further limit the size and mass of the system used to control the flaps.

[0075] In this case, advantageously, the synchronization ring 82 is arranged downstream of the lever 80 of each of the controlled convergence flaps 30.

[0076] It should be noted that the body 56A of the cylinder 56 can be rigidly fastened to the stator structure 38 in the same manner as in the known example shown in Figure 2 above.

[0077] In an alternative embodiment, the upstream support walls 90 may be connected to each other to form a single upstream support structure extending in 360 degrees. Similarly, the downstream support walls 92 may be connected to each other to form a single downstream support structure extending in 360 degrees.

[0078] This support structure can be directly integrated into the main body 86 of the synchronization ring 82.

Claims

1. A rear section of a turbojet engine, comprising: - Upstream stator structure (38); - A variable geometry nozzle (28) comprising a set of converging flaps (30) distributed around a longitudinal axis (11) of the rear portion of the turbojet engine, each converging flap comprising a panel (31) designed to guide exhaust gas (F4) within the variable geometry nozzle, and each converging flap having an upstream end (36) hinged to the upstream stator structure along a corresponding first hinge axis (A1); wherein at least some of the converging flaps (30), referred to as controlled converging flaps, each comprises a lever (80) rigidly fixed to the corresponding panel (31) and extending in a direction away from the longitudinal axis (11), the lever (80) carrying a support roller (96) rotatably mounted on the lever along an axis (94) parallel to the corresponding first hinge axis (A1); - A drive unit, the drive unit comprising a movable portion capable of axially moving relative to the upstream stator structure (38) according to instructions, In this configuration, the support roller (96) of the lever (80) of at least one of the controlled convergence flaps (30) is axially arranged between the upstream support wall (90) and the downstream support wall (92), which are rigidly fixed to the movable portion of the drive device, such that the support roller (96) of the lever is free to move relative to the upstream support wall (90) and the downstream support wall (92) at least in the radial direction (R) relative to the longitudinal axis (11), thereby: - During the downstream movement of the movable portion of the drive unit, the upstream support wall (90) pushes the lever (80) downstream, causing the convergent flap (30) to pivot along the corresponding first hinge axis (A1), resulting in the downstream end (46) of the convergent flap being brought closer to the longitudinal axis (11), and - During the upstream movement of the movable portion of the drive unit, at least if the turbojet engine stops, the downstream support wall (92) pushes the lever (80) upstream, causing the convergent flap (30) to pivot along the corresponding first hinge axis (A1), resulting in the downstream end (46) of the convergent flap moving away from the longitudinal axis (11).

2. The rear portion of the turbojet engine according to claim 1, wherein, One of the upstream support wall (90) and the downstream support wall (92) is connected to a movable part of the drive device via the other of the upstream support wall and the downstream support wall.

3. The rear portion of the turbojet engine according to claim 2, wherein, The outer connecting wall (98) connects the respective radially outer ends of the upstream support wall (90) and the downstream support wall (92) to each other.

4. The rear portion of the turbojet engine according to any one of claims 1 to 3, wherein, An upstream support wall (90) arranged opposite to the support roller (96) of each lever (80) and an upstream support wall (90) arranged opposite to the support roller (96) of the two closest levers (80) are circumferentially spaced apart, and a downstream support wall (92) arranged opposite to the support roller (96) of each lever (80) and a downstream support wall (92) arranged opposite to the support roller (96) of the two closest levers (80) are circumferentially spaced apart, thereby the upstream support wall (90) and the downstream support wall (92) form an annular row of support devices (100), each support device including one upstream support wall (90) and one downstream support wall (92).

5. The turbojet engine rear section according to claim 4, the turbojet engine rear section including a synchronizing ring (82) surrounding the set of converging flaps (30) or the upstream stator structure (38), and each of the support devices (100) being connected to a movable portion of the drive unit via the synchronizing ring.

6. The rear portion of the turbojet engine according to claim 4, wherein, For each support device (100), a first connecting sidewall (104) connects the corresponding first circumferential ends of the upstream support wall (90) and the downstream support wall (92) to each other, and a second connecting sidewall (106) connects the corresponding second circumferential ends of the upstream support wall (90) and the downstream support wall (92) to each other, the second circumferential ends being opposite to the first circumferential ends.

7. The rear portion of the turbojet engine according to any one of claims 1 to 3, wherein, The variable geometry nozzle also includes a set of expanding flaps (32) distributed around the longitudinal axis (11), the set of expanding flaps including a panel (33) designed to guide the exhaust gas flow (F4) within the variable geometry nozzle, and the set of expanding flaps having an upstream end (44) hinged to the downstream end (46) of the converging flap (30), thus the variable geometry nozzle is a converging-expanding nozzle.

8. A turbojet engine for an aircraft, comprising the rear portion according to any one of claims 1 to 7.

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