EP2635789A2

EP2635789A2 - Aircraft turbojet engine thrust reverser with a lower number of actuators

Info

Publication number: EP2635789A2
Application number: EP11832145.4A
Authority: EP
Inventors: Olivier Kerbler; Nicolas Dezeustre; Hervé HURLIN
Original assignee: Aircelle SA
Current assignee: Safran Nacelles SAS
Priority date: 2010-11-03
Filing date: 2011-10-28
Publication date: 2013-09-11
Also published as: CA2814384A1; CN103201491A; FR2966882A1; WO2012059677A2; BR112013009356A2; US20140131479A1; WO2012059677A3; RU2013124521A; FR2966882B1

Abstract

This cascade-type thrust reverser with one-piece moving cowl (23) comprises rails able to slide in guideways positioned on each side of a suspension pylon (8). This thrust reverser comprises just two actuators (43a, 43b) positioned near said rails and able to cause this cowl (23) to slide on said guideways between its direct-jet and reverse-jet positions. It also comprises means capable of compensating for forces that have a tendency to misalign said rails with respect to said guideways, thus preventing them from jamming in one another.

Description

Thrust reverser for an aircraft turbojet, with a reduced number of actuators

The present invention relates to a thrust reverser for an aircraft turbojet, with a reduced number of actuators.

An airplane is driven by several turbojets each housed in a nacelle for channeling the air flows generated by the turbojet engine which also houses a set of actuators providing various functions when the turbojet engine is in operation or stopped.

These actuating devices may include, in particular, a mechanical thrust reversal system.

A nacelle generally has a tubular structure comprising an air inlet upstream of the turbojet engine, a median section intended to surround a fan of the turbojet engine, a downstream section housing thrust reverser means and intended to surround the combustion chamber of the turbojet engine. , and is generally terminated by an ejection nozzle whose output is located downstream of the turbojet engine.

Modern nacelles are intended to house a turbofan engine capable of generating, by means of the fan blades, an air flow part of which, called a hot or primary flow, circulates in the combustion chamber of the turbojet engine, and of which the other part, called cold or secondary flow, circulates outside the turbojet through an annular passage, also called vein, formed between a shroud of the turbojet engine and u nn inner wall of the nacel. The two air fl ows are ejected from the turbojet engine from the rear of the nacelle.

The role of a thrust reverser is, during the landing of an aircraft, to improve the braking capacity thereof by redirecting forward at least a portion of the thrust generated by the turbojet engine. In this phase, the inverter 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 implemented to achieve this reorientation of the cold flow vary according to the type of inverter. However, in all cases, the structure of an inverter comprises movable covers (or doors) moved between a closed position or "direct jet" in which they close this passage and an open position or "reverse jet" in which they open. in the nacelle a passage for the deviated flow. These covers can perform a deflection function or simply activation other means of deflection.

In the case of a thrust reverser with grids, also known as a cascade reverser, the reorientation of the air flow is performed by deflection grids, the hood having a simple sliding function to discover or cover these grids.

The translation of the movable cowl takes place along a longitudinal axis substantially parallel to the axis of the nacelle. Reversed thrust flaps, actuated by the sliding of the hood, allow an obstruction of the cold flow vein downstream of the deflection grids, so as to optimize the reorientation of the cold flow to the outside of the nacelle.

It is known from the prior art, and in particular from document FR 2 916 426, a thrust reverser with gates, the movable cowl is in one piece and slidably mounted on slideways arranged on either side of the suspension pylon of the formed assembly. by the turbojet and its nacelle.

"Monobloc cowling" means a quasi-annular shaped cowl, extending from one side to the other of the pylon without interruption.

Such a hood is often referred to by the Anglo-Saxon terms "O-duct", alluding to the ferrule shape of such hood, as opposed to "D-duct", which actually comprises two half-hoods. each extending on a half-circumference of the nacelle.

The sliding of an "O-duct" type hood between its "direct jet" and "reverse jet" positions is conventionally ensured by a plurality of actuators, of the mechano-electric type (for example: worm gear actuated by a electric motor and moving a nut) or hydraulic (jacks actuated by pressurized oil).

Typically, there are four or six actuators, namely respectively two or three actuators distributed on each half of the thrust reverser, on either side of the suspension pylon.

The present invention aims to simplify these actuating means, both to reduce costs and to reduce the mass of the nacelle.

This object of the invention is achieved with a thrust reverser with grids and with a moveable one-piece cowling comprising rails able to slide in slideways arranged on either side of a suspension pylon. comprising only two actuators disposed near said rails and able to slide said cover on said rails between its direct jet and reverse jet positions, and also comprising means able to compensate for the efforts tending to misalign said rails with respect to said slides, and thus avoiding their mutual jamming, remarkable in that said means are selected from the group comprising:

means for compensating for the tilting torque of the movable hood caused by the pressurization of the vein of the cold flow of the inverter, and

inversion reversing flaps, arranged so as to exert a thrust force on the upstream edge of the inner wall of said movable cowl.

The presence of only two actuators is a considerable simplification compared to the thrust reversers of the prior art, this simplification making it possible to achieve substantial cost and mass reductions.

However, this simplification entails risks of jamming of the sliding of the movable cowling, which jamming can be avoided thanks to the above-mentioned compensation means.

Indeed, because of the substantially conical shape of the inner wall of the movable cowl, the resultant of the pressure forces of this cold air tends to form a tilting torque of the movable cowl with the resultant of the forces exerted by the actuators. ; by compensating for this torque, it reduces the risk of jamming.

With regard to the thrust reversing flaps, the thrust force, present both at the opening and closing of the movable cowl, makes it possible to apply a force distributed in a substantially homogeneous manner over the entire periphery of the moving cowl which makes it possible to reduce the intensity of the aforementioned tilting torques.

According to other optional features of the thrust reverser according to the invention:

said compensating means comprise means of pressurizing the outer wall of said movable cowl: by pressurizing the outer wall of the movable cowl, whose shape is also conical, but inverted with respect to that of the inner wall of the cowl, substantially reduced the effect of the above-mentioned tilting torque; - Average pressurization means include a seal disposed upstream of the outer wall of said movable cover, and an absence of seal upstream of the inner wall of the movable cover: by removing the seal of the inner wall and transferring it to the outer wall, the cold air that is under pressure in the cold flow vein is allowed to fill the space between the inner and outer walls of the mobile cowl, and thus pressurize at least part of the outer wall;

- The said pressurizing means comprise a seal on the inner wall of said movable cowl, associated with a limited leak on the outer wall and at least one expansion valve located through the inner wall: the role of these pressure reducers is d ensure a pressure in the space between the inner and outer walls of the movable cowl that cancels the resultant axial forces of the movable cowl; optionally, this regulator can be controlled.

Other characteristics and advantages of the present invention will emerge in the light of the description which follows, and on examining the appended figures, in which:

FIG. 1 is a general schematic representation of a turbojet engine nacelle having a thrust reverser according to the invention, that is to say having a one-piece mobile cowl ("O-duct" type inverter), of which interior is seen in transparency;

- Figure 2 is a schematic representation in longitudinal half-section of the nacelle of Figure 1;

- Figures 3 to 5 are longitudinal half-sectional views of the thrust reverser of the nacelle of Figures 1 and 2, in three successive positions;

- Figure 6 shows schematically in cross section, the positioning of the two actuators of the movable cover of the thrust reverser of Figures 3 to 5;

- Figure 7 shows schematically, in longitudinal section, the tilting torque which is subject to the movable cover;

FIG. 8 shows in a diagrammatic manner, in longitudinal section, an appropriate positioning of a seal on the movable cowl of the thrust reverser according to the invention; and

FIG. 9 schematically shows, in detail, the mechanism found in zone XII of FIG. 5. In all of these figures, identical or similar references denote identical or similar organs or sets of members.

With reference to FIGS. 1 and 2, a nacelle 1 is intended to constitute a tubular housing for a turbojet engine 3 and serves to channel the flows of hot air 5 and cold 7 generated by this turbojet engine 3, as indicated in the preamble of FIG. this description.

This nacelle 1 is intended to be suspended from a tower 8, itself fixed under the wing of an aircraft.

As indicated previously, the nacelle 1 has, in general, a structure comprising an upstream section 9 forming an air inlet, a central section January 1 surrounding the fan 13 of the turbojet engine 3 and a downstream section 15 surrounding the turbojet engine 3.

The downstream section 15 comprises an external structure 17 comprising a thrust reverser device and an internal structure 19 for refitting the engine 3 of the turbojet engine defining with the external structure 17 the stream of the cold stream 7, in the case of the turbojet nacelle double flow as presented here.

The thrust reverser device comprises a cover 23 mounted to move in translation in a direction substantially parallel to the longitudinal axis A of the nacelle 1.

This cover 23 is able to pass alternately from a closed position (position shown in Figures 1 and 2) in which it ensures the aerodynamic continuity of the lines of the downstream section 15 of the nacelle 1 and covers grids 25 of flow deflection of air, to an open position in which it opens a passage in the nacelle 1 by discovering these deflection grids 25.

More specifically, in the context of the present invention, the movable cover 23 is in one piece, that is to say it comprises a single one-piece mobile cover, of quasi-annular shape, extending from one side to the other. another of the pylon 8 without interruption (mobile cowl called "O-duct").

The deflection grids 25 each have a plurality of deflector vanes.

As illustrated in FIG. 2, the downstream section 15 may further comprise a front frame 27 which extends the hood 23 upstream and ensures the attachment of the downstream section 15 with the central section 1 1 surrounding the fan 13 of the turbojet engine.

The translation of the movable cowl 23 downstream of the nacelle releases therein an opening through which the cold jet of the turbojet engine can escape at least partially, this portion of the flow being reoriented towards the front of the nacelle by the deflection grids 25, thereby generating a counter-thrust capable of contributing to the braking of the aircraft.

The orientation of the cold flow towards the deflection grids 25 is effected by a plurality of inversion flaps 29 (see FIGS. 3 to 5 and 9), distributed on the inner circumference of the movable cowl 23, each mounted pivoting between a retracted position. (see FIGS. 3 and 4) in which these flaps 29 ensure the internal aerodynamic continuity of the cold flow duct 7 and an extended position in which, in a thrust reversal situation, they at least partially close this vein and deflect the flow cold through deflection grids 25.

Referring now more particularly to Figures 3 to 5, on which we can see a thrust reverser according to the invention in three successive positions.

In FIG. 3, the thrust reverser can be seen in the "direct jet" position, that is to say in the position where the cold flow 7 flows directly from upstream to downstream of the nacelle: this position corresponds to the cruise flight situation of the aircraft.

In FIG. 4, the movable cowl 23 can be seen progressing towards the "reverse jet" position of FIG. 5.

In the latter position, the cold flow is deflected by the thrust reversal flaps 29 through the deflection grids 25, as indicated by the arrow F, for braking the aircraft.

More specifically, in the embodiment shown in FIGS. 3 to 5, the thrust reversal grids 25 are of the retractable type, that is to say that they are capable of sliding from an upstream position (FIGS. 3 and 4) at a downstream position (FIG. 5), under the effect of the opening of the movable cowl 23.

As can be seen in FIG. 9, the downstream sliding movement of the thrust reversal grids 25 is effected by abutments 31 arranged appropriately on the upstream edge of the outer wall 33 of the movable cowl 23. . More precisely, the thrust reversing flaps 29 are each mounted pivoting and sliding inside grooves 34 integral with the thrust reversal grids 25.

A first connecting rod 35 connects the pivoting and sliding end of each flap 29 to the fixed front frame 27, or to any other fixed structure, and a second connecting rod 37 is articulated on the one hand substantially mid-length of the inverting flap. thrust 29, and secondly, in the upstream zone of the thrust reversal grids 25.

When the movable cowl 23 passes from the position of FIG. 3 to that of FIG. 4, the two connecting rods 35, 37 and the associated thrust reverser shutter 29 remain motionless, allowing this thrust reversal shutter to be released. of the cavity defined by the outer 33 and inner walls 41 of the movable cowl 23.

When the movable cowl 23 continues to slide to reach the position shown in FIG. 5, the stops 31 disposed on the upstream edge of the outer wall 33 of this movable cowl have the effect of sliding the thrust reversal grids 25 towards a downstream position visible in Figure 5.

Under the effect of this sliding, the first link 35 has the effect of sliding the point of articulation of the end of the thrust reversal flap 29 inside the groove 34, allowing the extraction of this thrust reversal shutter of the cavity defined by the walls 33 and 41.

The second connecting rod 37 has the effect of pivoting the thrust reverser flap 29 to its closed position of the cold flow stream 7, visible in FIG. 5, making it possible to orient this cold flow through the thrust reversal grids 25, upstream of the nacelle 1.

The actuating means of the movable cowl 23, permitting its sliding from one to the other of the positions visible in FIGS. 3 to 5, are schematically represented in FIG. 6: these means comprise two single actuators 43 a and 43b disposed in the upper part of the movable cowl (that is to say upwards of the drawing board 3/4 appended hereto), on either side of the suspension pylon 8.

These actuators may be hydraulic cylinders, or actuators of the mechanical-electrical type, such as worm and nut systems. Due to the substantially frustoconical shape of the inner wall 41 of the movable cowl 23, which shape flares downstream of the nacelle, the resultant RP of the cold air pressure forces on this inner wall is directed towards the upstream of the nacelle, as can be seen in FIG. 7, when the mobile cowl is in the "direct jet" position.

This resultant RP therefore has the effect of generating a tilting torque with the resultant RA of the forces exerted by the actuators 43a and 43b during the opening of the movable cowl 23.

This tilting torque may have the consequence of blocking the rails (not shown) disposed in the upper part of the movable cowl 23, and allowing the sliding of the mobile cowl in two slides (not shown) d isposées on both sides suspension pylon 8.

To avoid this, it is proposed to deport the gasket which is usually on the upstream edge B1 of the inner wall 41 of the movable cowl 23 to the edge B2 of the outer wall 33 of the mobile cowl.

In doing so, the cold air 7 under pressure in the cold air duct of the nacelle fills the cavity delimited by the external and internal walls 33 of the movable cowl 23.

In this way, and because of the frustoconical shape of the outer wall 33, narrowing downstream of the nacelle, the resultant of the pressure forces exerted by the cold air is oriented in the same direction as the resultant RA exerted by the actuators 43a and 43b at the opening of the movable cowl 23: in this way the tilting torque generated by the pressure of the air inside the stream of the cold flow is eliminated, and the risks of jamming caused by this pressure.

In another variant, it is possible to envisage a seal disposed upstream of the inner wall 41, associated with a limited leakage on the outer wall and at least one expansion valve passing through the inner wall 41: the role of this regulator is to ensuring a pressure in the space between the inner walls 41 and outer 43 of the movable cowl, which cancels the resultant axial forces of the movable cowl; optionally, this regulator can be controlled.

Another origin of the risks of jamming the rails of the movable cowl 23 in their associated slides, is the upwardly shifted positioning of the actuators 43a and 43b, that is to say of their highly asymmetrical positioning with respect to a horizontal plane intersecting the nacelle: such asymmetrical positioning is in fact intrinsically generating efforts of buttressing between the rails of the movable cowl 23 and their associated slides, which jamming can cause friction that can lead to blocking situations.

One solution to reduce the risk of blockage caused by such an overwrapping is to place each actuator 43 in the extension of the associated rail 45 of the movable cowl 23.

With this particular arrangement, the thrust and pulling forces exerted by the actuators 43a and 43b are exerted directly in the sliding axis of each rail with its associated slideway, thus eliminating all the tilting moments and the risks of overloading. associated stubbornness and jamming.

Another solution to reduce these risks of jamming and jamming may be to attach a cable 55 to the end of each rail 45 of the movable cover 23, as can be seen in Figures 10 and 1 1.

Another way, complementary to the previous ones to reduce the tilting torque of the movable cowl 23 inherent in the asymmetric positioning of the actuators 43a, 43b with respect to the horizontal plane of the nacelle, is to use the thrust reverser flaps 29 themselves.

More precisely, as can be seen in particular in FIG. 5, it is possible to choose the geometry of the movement of the thrust reverser flaps 29 so that they come into abutment against the upstream edge B1 of the inner wall 41 of the movable cowl .

In this way, these thrust reversal flaps 29, under the effect of the thrust exerted by the cold flow 7, come to bear on the entire circumference of the edge B1 of the inner wall 41, thus exerting on this inner wall. , and therefore on the entire movable cowl 23, a thrust force distributed circumferentially.

This circumferential distribution of the force makes it possible to counteract the tilting torque generated by the asymmetrical positioning of the actuators 43a and 43b, and thus actively contributes to reducing the risk of jamming and jamming.

As can be seen in the light of the above, the present invention provides a thrust reverser particularly simplified design and lightened, through the use of two actuators only, arranged on either side of the suspension pylon of Platform. This limitation of the number of actuators, as well as their particular positioning, poses difficulties resulting from the tilting torques generated on the one hand by the pressurization of the cold air in the nacelle, and on the other hand by the asymmetric forces generated by these actuators, when opening and closing the movable hood.

To solve these difficulties, and allow such use of two actuators only, the aforementioned means, used alone or in combination, are used to compensate for the tilting forces of the movable cover of the thrust reverser.

It should be noted that the use of a thrust reverser with retractable grilles (see FIGS. 3 to 5) is entirely optional in the context of the present invention.

Of course, the present invention is not limited to the embodiments described and shown, provided for purely illustrative purposes.

Claims

1. A thrust reverser with grilles and with a moveable one-piece hood (23) comprising rails (45) able to slide in slideways arranged on either side of a suspension pylon (8), comprising only two actuators (43a, 43b) ) disposed near said rails (45) and able to slide this cover (23) on said rails between its direct jet and reverse jet positions, and also comprising means capable of compensating for the efforts tending to misalign said rails (45) by with respect to said slides, and thus to avoid their mutual jamming, characterized in that said means are selected from the group comprising:

means for compensating the tilting torque (RA, RP) of the movable cowl (23) caused by the pressurization of the vein of the cold flow (7) of the inverter, and

- Reversing thrust flaps (29) of the inverter, arranged to exert a thrust force on the upstream edge (B1) of the inner wall of said movable cowl.

2. Inverter according to claim 1, characterized in that said tilt torque compensation means comprise means for pressurizing the outer wall (33) of said movable cowl (23).

3. Inverter according to claim 2, characterized in that said pressurizing means comprise a seal disposed upstream of the outer wall (33) of said movable cover (23), and an absence of seal upstream of the inner wall. (41) of this movable hood (23).

4. thrust reverser according to claim 2, characterized in that said pressurizing means comprise a seal disposed upstream of the inner wall of said movable cowl, associated with a limited leak on the outer wall and at least one expander located through the inner wall.

5. Nacelle (1) for aircraft turbojet (3), characterized in that it comprises a thrust reverser according to any one of the preceding claims.