FR3038587A1 - AIRCRAFT TURBOBOREACTOR NACELLE, PROPULSIVE ASSEMBLY COMPRISING A BOAT, AND AIRCRAFT HAVING AT LEAST ONE PROPULSIVE ASSEMBLY - Google Patents

Abstract

The invention relates to an aircraft turbojet engine nacelle, the nacelle (1) comprising a thrust reversal system, the thrust reverser system comprising a movable cowl (20), reversing gates (22) ) and locking flaps (24), the nacelle comprising at least two guide rails (30) of the reversing gates (22), the reversing gates being integral in translation with at least two slides (32). , each slider (32) cooperating with a guide rail (30), the ratio between the length of the sliders (32) and the useful length of the guide rails (30) being less than or equal to 0.2.

Description

The invention relates to a turbojet engine nacelle, to a propulsion unit equipped with such a nacelle, and to an aircraft provided with such a propulsion unit.

An aircraft is propelled by several turbojets each housed in a nacelle, each nacelle furthermore containing a set of ancillary actuating devices related to its operation and providing various functions when the turbojet engine is in operation or stopped.

Modern nacelles are intended to house a turbojet engine capable of generating through the blades of the rotating fan a flow of hot gases (also called primary flow) and a cold air flow (also called secondary flow) which circulates outside the turbojet engine through an annular passage, also called vein, formed between two concentric walls of the nacelle. The primary and secondary flows are ejected from the turbojet engine from the rear of the nacelle.

A turbojet engine nacelle generally has a tubular structure comprising: a front section, or air intake, located in front of the turbojet engine; a median section intended to surround the fan of the turbojet engine; a rear section, intended to surround the combustion chamber of the turbojet, and generally embodying means of thrust reversal; an ejection nozzle, the outlet of which is situated downstream of the turbojet engine.

The rear section generally has an external structure, which defines, with a concentric internal structure, called "Inner Fixed Structure" (IFS), the annular vein used to channel the flow of cold air.

The thrust reversal means allow, during the landing of an aircraft, to improve the braking capacity thereof by redirecting forward a majority fraction of the thrust generated by the turbojet engine. In this phase, the inverter generally obstructs the cold flow vein and directs the latter towards the front of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels of the aircraft. The means used to achieve this reorientation of the cold flow vary according to the type of inverter. A common configuration is that of thrust reversers known as "gate". In this type of thrust reverser, the outer cover of the rear section is sliding. The translation towards the rear of this sliding hood makes it possible to discover inversion grids placing in communication the cold flow vein and the outside of the nacelle. The translation of the sliding cover also makes it possible to deploy locking flaps in the cold flow vein. Thus, by the combined action of the locking flaps and the inversion grids, the cold flow is redirected towards the front of the nacelle.

As mentioned above, the thrust reversal means are housed in the rear section of a nacelle. Three types of structural configuration for the rear section are mainly known, namely the so-called "C" (or "C-duct"), "D-duct" and "D-duct" structures. "O" (or "O-duct").

In a nacelle structure D, the inner and outer structures of the rear section of the nacelle are secured to one another, through two islands of links called birfucations. The bifurcations are arranged respectively according to the positions known as "at twelve o'clock" (upper bifurcation) and "at six o'clock" (lower bifurcation). The sliding cowl is in this case mounted in translation on the outer structure of the rear section. The sliding cover is generally made up of two half-parts.

In an O or C-shaped nacelle, the rear section is configured such that a lower bifurcation is not required. This represents a great gain in efficiency for the propulsion unit since the cold flow vein is no longer obstructed in its lower part, as is the case for the D structures. Moreover, the structures in O or in C also allow significant gains in terms of mass.

In an O or C structure, the sliding cowl, or moving cowl, is generally mounted on rails disposed on either side of the pylon (or mast) for suspending the propulsion unit. These rails can be placed directly on the pylon, or on an intermediate element attached to the pylon when the propulsion unit is mounted. The hood is guided and supported only at these rails, so only near the "twelve o'clock" position.

Moreover, in the case of a grid inverter, the grids, which ensure the redirection of the cold flow, can be sliding. Thus, the grids can slide between a retracted (or advanced) position, in which the grids are concealed inside the nacelle, and an extended position (or retracted), in which the grids are discovered. The grids are then guided by at least two rails, arranged in the extension or not of the rails supporting the sliding cover. The grids can advantageously be integral in translation of the sliding cowl.

When the grids of the thrust reverser are sliding, the forces generated during the thrust reversal phase and during the retraction of the movable cowl and the grids can lead to the locking of the sliding elements. Indeed, the forces generated by the grids induce at the guide rails forces and moments likely to cause jamming of the sliding elements on the rails. The invention proposes to solve the disadvantages of the state of the art by eliminating any risk of jamming at the sliding guide rails. For this purpose, the invention relates to an aircraft turbojet engine nacelle, the nacelle comprising a thrust reverser system, the thrust reverser system comprising a movable cowl, sliding inversion gates and flaps blocking device, the nacelle comprising at least two guide rails of the reversing gates, the reversing gates being integral in translation with at least two slides, each slide cooperating with a guide rail, the ratio between the length of the slides and the useful length of the guide rails being less than or equal to 0.2.

Thus, by providing a short type of guiding system, that is to say with a slider having a length much shorter than the useful length of the guide rails, it avoids any bracing of the guide rails of the grids. inversion, and we avoid the jamming grids during their movement.

In one embodiment, the slider is attached to a peripheral frame before integral with the inversion grids.

In one embodiment, the slider is further attached to a spar, the spar being attached to the front peripheral frame and to a rear peripheral frame integral with the inversion grids.

In one embodiment, each slide has a connecting portion with the corresponding guide rail, this connecting portion forming a cylinder portion and cooperating with a complementary shape of the corresponding guide rail. The invention also relates to a propulsion unit for an aircraft, comprising a turbofan engine, the propulsion unit comprising a nacelle as defined above. Finally, the invention relates to an aircraft comprising at least one propulsion unit as defined above, the propulsion unit being supported by a pylon, the pylon having guide rails of the movable cowl of the nacelle.

The present invention will be better understood on reading the detailed description which follows, made with reference to the appended drawings, among which: FIGS. 1a and 1b, represent a nacelle according to the invention, respectively in "direct jet" configuration and "Reverse jet"; FIGS. 2a and 2b show a portion of the rear section of the nacelle of FIGS. 1a and 1b, with the thrust reversal system respectively in the retracted and deployed position; FIGS. 3a and 3b are detailed views of FIG. 2a; FIGS. 3c and 3d are detailed views of FIG. 2b; - Figures 4a and 4b are partial views showing the guide system and the slider.

FIGS. 1a and 1b show a view of a nacelle 1 according to the invention. This conventionally comprises an air inlet 2, a median section 3, and a rear section 4. In FIG. 1a, the platform 1 is shown alone, whereas in FIG. nacelle 1 mounted on a pylon 5 (also called "reactor mast"). Furthermore, FIG. 1a shows the nacelle in "direct jet" configuration, that is to say with the thrust reverser system in the retracted position, while FIG. 1b shows the nacelle in "reverse jet" configuration, that is to say with the thrust reversal system in the deployed position. Thus, it can be seen in FIG. 1b that a movable cowl 20 of the rear section 4 is in the retracted position, revealing a set of reversing grids 22. In the example, the movement of the movable cowl 20 is supported and guided by rails 50 arranged on either side of the pylon 5.

In the example, the structure of the nacelle is of type "in 0" (or "O-duct") and therefore does not include a bifurcation in the lower part of the cold flow vein. It should be noted that the invention is also applicable to a nacelle structure C.

FIGS. 2a and 2b show a portion of the rear section of the nacelle of FIGS. 1a and 1b, showing the elements of the thrust reversal system respectively in the retracted position and in the deployed position.

The thrust reversal system comprises a movable hood 20, in one piece, which forms the outer surface of the rear section of the nacelle. The mobile cowl 20 is slidably mounted, in the example by means of the rails 50, integral with the pylon 5 supporting the propulsion unit (ie the assembly formed by a turbojet and the associated nacelle). The thrust reversal system further comprises reversing grids 22 and locking louvers 24 movable in rotation. The inversion grids 22 are sliding and are integral in translation with the movable cowl 20. The thrust reverser system comprises actuators (not shown), in particular electromechanical actuators, making it possible to slide the assembly formed by the moving cowl and the inversion gates 22 between a retracted position (FIG. 2a) and an extended position (FIG. 2b), and vice versa. This translation takes place along a longitudinal axis of the nacelle, corresponding to the longitudinal axis of the engine.

When the thrust reverser system is in the retracted position (FIG. 2a): the moving cowl is in the retracted position, corresponding to an advanced position in which it ensures the aerodynamic continuity with the median section of the nacelle; - The locking flaps 24 are in the retracted position, in which position they are aligned with the inner surface of the movable cover 20; the inversion gates 22 are in the retracted (or advanced) position, in which position they are arranged around the fan casing of the turbojet engine.

When the thrust reversing system is in the deployed position (FIG. 2b): the movable cowl is in the extended position, corresponding to a retracted position, in which it discovers the reversing grids 22 which are in their retracted position; - The blocking flaps 24 are in the deployed position, in which position they at least partially obstruct the flow of cold flow; - The inversion grids 22 are in the deployed position (or retracted), in which position they are arranged behind the fan housing of the turbojet, and wherein they redirect the cold flow to the outside of the nacelle.

It should be noted that the inverting grids 22 being sliding grids, they are in the example linked in translation to the movable cowl 20, and the relative position of the reversing grids 22 with respect to the movable cowl 20 does not vary. not during the deployment or retraction of the thrust reversal system.

The reversing grids 22 are integral with a front peripheral frame 26 and a rear peripheral frame 27, the rear peripheral frame 27 being itself integral with the movable cowling 20. Several housings 28 are provided for the actuators of the rear seat 27. thrust reversal. These housings 28, four in number in the example of FIGS. 2a and 2b, are arranged between some of the inverting grids 22.

On either side of the so-called "twelve o'clock" position are two guide rails 30 for guiding the reversing gates 22. The guide rails 30 each cooperate with a slide 32, each slide 32 being integral with a spar 29. Each spar 29 is attached to both the front frame 26 and the rear frame 27.

As can be seen in FIGS. 3a, 3b, 3c, 3d, 4a and 4b, the slider 32 ensures short guidance of the inversion grids. Indeed, the total length of the slider is very small in front of the guide length, that is to say the useful length of the guide rails 30. In the example, the guide length provided by the guide rails 30 is 500 mm, while the length L (see Figure 4b) of the slider 32 is 80 mm. In the context of the invention, it will be ensured that the ratio between the length L of the sliders 32 and the useful length of the guide rails 30 is less than 0.2. This avoids any risk of jamming due to an arching of the rails under the forces generated by the inversion grids, especially during the thrust reversal phase.

Figures 4a and 4b are partial views in which the inversion grids are not visible. In Figure 4b, the guide rail 30 is not visible. It can thus be observed that the slider 32 is fixed both to the front peripheral frame 26 and to the spar 29. The slider 32 has a guide portion 320, a portion of which forms a cylinder of circular section, adapted to cooperate with a complementary shape of the guide rail 30, as shown in Figure 3b.

Although the invention has been described in connection with a particular embodiment, it is obvious that it is not limited thereto and that it includes all the technical equivalents of the means described and their combinations.

Claims (6)

1. Aircraft turbojet engine nacelle, the nacelle (1) comprising a thrust reversal system, the thrust reverser system comprising a movable cowl (20), sliding inversion grids (22) and flaps locking device (24), the nacelle comprising at least two guide rails (30) of the inversion grids (22), the reversing grids being integral in translation with at least two sliders (32), each slider (32) ) cooperating with a guide rail (30), the ratio between the length of the sliders (32) and the useful length of the guide rails (30) being less than or equal to 0.2. 2. Platform according to claim 1, wherein the slider (32) is fixed to a front peripheral frame (26) integral with the inversion grids (22). The nacelle of claim 2, wherein the slider (32) is further attached to a spar (29), the spar (29) being attached to the front peripheral frame (26) and to a rear peripheral frame (27) secured to reversing gates (22). 4. Nacelle according to one of the preceding claims, wherein each slide (32) has a connecting portion (320) with the corresponding guide rail (30), this connecting portion forming a cylinder portion and cooperating with a shape complementary to the corresponding guide rail (30). 5. Aircraft propulsion assembly, comprising a turbofan engine, the propulsion unit comprising a nacelle (1) according to one of the preceding claims. 6. Aircraft comprising at least one propulsion unit according to the preceding claim, the propulsion unit being supported by a pylon (5), the pylon (5) having guide rails of the movable cowl of the nacelle.