Thrust reverser for an aircraft turbojet engine nacelle

Abstract

The present disclosure concerns a thrust reverser for an aircraft turbojet engine nacelle including at least one movable thrust reverser cowling, a means for locking the cowling, an outlet nozzle having a variable cross-section that is arranged in the downstream extension of said cowling and that is movable, and at least one actuator that includes an actuating rod capable of moving the variable nozzle and the movable cowling, remarkable in that the reverser is provided with a passive coupler.

Claims

1. A thrust reverser for an aircraft turbojet engine nacelle comprising: a thrust reverser cowl movable in translation along a direction substantially parallel to a longitudinal axis (A) of the aircraft turbojet engine nacelle, between a direct jet position and a reverse jet position; an outlet nozzle with a variable section which is arranged in a downstream extension of said cowl and which is movable between at least one reduced ejection section position, one increased ejection section position and one intermediate neutral position; at least one actuator which comprises a body mounted on a fixed structure of the thrust reverser and an actuating rod, said rod being adapted to drive in displacement the variable section of the nozzle and the movable cowl; and a passive coupler comprising: a hollow housing secured to the thrust reverser cowl, and which delimits internally a cavity extending axially generally along an axis (B) of the actuating rod and which is delimited by a radial upstream wall and by a radial downstream wall; a piston fastened on the actuating rod of the at least one actuator and which is slidably mounted in the housing of the passive coupler by hermetically dividing said cavity into two compartments comprising an upstream compartment located between the upstream wall and the piston and a downstream compartment located between the downstream wall and the piston, each compartment being filled with a fluid; and a unidirectional flow limiter providing a fluid connection between the two compartments of the housing, said flow limiter limiting a fluid circulation rate in the direction of a fluid flow from the downstream compartment to the upstream compartment, and enabling a free circulation of the fluid in the direction of fluid flow from the upstream compartment to the downstream compartment.

2. The thrust reverser according to claim 1, wherein, in the reduced ejection section position for the nozzle, the piston is in abutment against the downstream wall of the housing.

3. The thrust reverser according to claim 1, wherein, in the increased ejection section position for the nozzle, the piston is in abutment against the upstream wall of the housing.

4. The thrust reverser according to claim 1, wherein the flow limiter comprises a first pipe providing the fluid connection between the two compartments of the housing, a hydraulic device integrating on the first pipe a throttle valve.

5. The thrust reverser according to claim 4, wherein the throttle valve is adjustable.

6. The thrust reverser according to claim 4, wherein the flow limiter integrates on the first pipe a pressure regulator.

7. The thrust reverser according to claim 6, wherein the pressure regulator is placed on the first pipe having its inlet in direct connection with the downstream compartment of the housing and having its outlet in direct connection with the throttle valve.

8. The thrust reverser according to claim 4, wherein the flow limiter comprises a second pipe in parallel with the first pipe and providing the fluid connection between the two compartments of the housing, said flow limiter integrating on the second pipe a check valve inhibiting the circulation of the fluid in the second pipe in the direction of a fluid flow flowing from the downstream compartment to the upstream compartment.

9. An aircraft turbojet engine nacelle equipped with a thrust reverser according to claim 1.

Description

DRAWINGS

(1) In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

(2) FIG. 1 is an overall perspective view, which illustrates an aircraft turbojet engine turbojet engine nacelle equipped with a thrust reverser and a variable nozzle;

(3) FIG. 2 is a schematic view in longitudinal section, which illustrates the movable cowl of the thrust reverser in the direct jet position and the passive coupler according to the present disclosure;

(4) FIG. 3 is a schematic view in longitudinal section, which illustrates the movable cowl of the thrust reverser in the reverse jet position and the passive coupler according to the present disclosure;

(5) FIG. 4 is a schematic detail view in longitudinal section, which illustrates the passive coupler of FIG. 2 in a position corresponding to a reduced ejection section position of the nozzle according to the teachings of the present disclosure;

(6) FIG. 5 is a schematic detail view in longitudinal section, which illustrates the passive coupler of FIG. 2 in a position corresponding to an intermediate neutral position of the nozzle according to the teachings of the present disclosure;

(7) FIG. 6 is a schematic detail view in longitudinal section, which illustrates the passive coupler of FIG. 2 in a position corresponding to an increased ejection section position of the nozzle according to the teachings of the present disclosure;

(8) FIG. 7 is a schematic detail view in longitudinal section, which illustrates the passive coupler of FIG. 2 in a position corresponding to a reverse jet position of the movable cowl of the thrust reverser according to the teachings of the present disclosure; and

(9) FIG. 8 is a schematic and zoomed view of the passive coupler of FIG. 2 according to the teachings of the present disclosure.

(10) The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

(11) The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

(12) In the description and claims, the longitudinal, vertical and transverse terminology will be used without restriction with reference to the trihedron L, V, T indicated in figures, whose axis L is parallel to the axis of the aircraft turbojet engine nacelle.

(13) It should be also noted that, in the present patent application, the terms upstream and downstream must be understood relative to the circulation of the air flow inside the propulsion unit formed by the nacelle and the turbojet engine, that is to say from the left to the right of FIGS. 1 to 7.

(14) In all of these figures, identical or similar references represent identical or similar organs or assemblies of organs.

(15) FIG. 1 shows a turbojet engine nacelle 10 for an aircraft, which extends axially along a longitudinal axis A.

(16) The aircraft turbojet engine nacelle 10 includes a fixed front portion 12 which includes a central fastening beam 14 on the aircraft, and a movable rear portion 16.

(17) The movable rear portion 16 includes a thrust reverser 18 which comprises a thrust reverser cowl 20 and a variable-section ejection nozzle 22 arranged in the downstream extension of the cowl 20.

(18) The thrust reverser cowl 20 is mounted movable in translation along a direction substantially parallel to the longitudinal axis A of the aircraft turbojet engine nacelle 10, between a direct jet position shown in FIG. 2, in which the cowl 20 opens into the aircraft turbojet engine nacelle 10 a passage intended for the diverted air flow, and a reverse jet position shown in FIG. 3 in which the cowl 20 closes the passage.

(19) The thrust reverser 18 is equipped with means (not shown) for diverting the air flow which are, for example, of the fixed cascade type or of the movable cascade type.

(20) The cowl 20 is driven in displacement by means of a plurality of cylinder 24, only one of which is described below and shown in FIGS. 2 to 5 and 7.

(21) In addition, the cowl 20 is associated with a locking means (not shown in FIGS. 2 and 3 and having the reference 15 in FIGS. 4 to 7) allowing to immobilize the cowl 20 in its direct jet position (shown in FIGS. 2, 4, 5 and 6) and to release the cowl 20 so that it can switch into the reverse jet position (shown in FIGS. 3 and 7) selectively.

(22) The variable-section outlet nozzle 22 is movably mounted on the movable portion 16 between at least one reduced ejection section position illustrated in FIG. 4, one increased ejection section position illustrated in FIG. 6 and one intermediate neutral position illustrated in FIG. 5.

(23) Each of the positions of the nozzle 22 here corresponds to a distinct inclination of the flaps 25 (only one of which is shown in FIGS. 2 to 7) which are pivotally mounted on the cowls 20 of the thrust reverser 18 in order to vary the ejection section of the nozzle 22.

(24) For this purpose, the cylinder 24 includes a body 26 mounted on the fixed structure of the thrust reverser 18 and an actuating rod 28 which is adapted to selectively drive in displacement the variable nozzle 22 or the assembly constituted by the variable nozzle 22 and the movable cowl 20.

(25) To this end, the thrust reverser 18 is equipped with a passive coupler 30, shown in detail in FIGS. 4 to 6, which includes a housing 32 fastened on the thrust reverser cowl 20.

(26) The housing 32 of the coupler 30 internally delimits a cavity 34 having a hollow cylindrical shape which extends axially along an axis (not schematized) parallel to the axis of the rod 28 for actuating the cylinder 24.

(27) The cavity 34 is delimited radially by a radial upstream wall 36 and by an radial downstream wall 38 which are opposite and each pierced by a through-hole 40 along the axis B, for the passage of the actuating rod 28 which passes through the housing 32 from side to side.

(28) In addition, the coupler 30 includes a piston 42 which is fastened on the actuating rod 28 and which is slidably mounted in the body 32 of the coupler 30, by hermetically dividing the cavity 34 into an upstream compartment 44 and into a downstream compartment 46. Each compartment 44, 46 is filled with an incompressible hydraulic fluid, such as, for example, the Skydrol AS1241 type IV and V fluids marketed by the Eastman Company. The upstream compartment 44 is provided with an upstream orifice 84 placed at the periphery close to the upstream wall 36 and the downstream compartment 46 is provided with a downstream orifice 86 placed at the periphery close to the downstream wall 38.

(29) The coupler 30 is configured such that:

(30) as shown in FIG. 4, in the reduced ejection section position for the nozzle 22, the piston 42 is substantially in abutment against the downstream wall 38 of the housing 32, and more precisely the piston 42 is in abutment against a downstream abutment member 76 (for example, an O-ring seal) placed close to the downstream wall 38 of the housing 32, with a sufficient spacing vis--vis this downstream wall 38 so that the piston 42 does not plug the downstream orifice 86;

(31) as shown in FIG. 6, in the increased ejection section position for the nozzle 22, the piston 42 is substantially in abutment against the upstream wall 36 of the housing 32, and more precisely the piston 42 is in abutment against an upstream abutment member 74 (for example, an O-ring seal) placed close to the upstream wall 36 of the housing 32, with a sufficient spacing vis--vis this upstream wall 36 so that the piston 42 does not plug the upstream orifice 84; and

(32) as shown in FIG. 5, in the neutral intermediate position for the nozzle 22, the piston 42 is located halfway between the downstream wall 38 and the upstream wall 36 of the housing 32.

(33) Also, the coupler 30 is equipped with a unidirectional flow limiter 50 providing the fluid connection between the two compartments 44, 46 of the housing 42, via respectively the upstream orifice 84 and the downstream orifice 86. This hydraulic flow limiter 50 is designed to:

(34) limit the fluid circulation rate in the direction of a fluid flow flowing from the downstream compartment 46 to the upstream compartment 44, and

(35) enable a free circulation of the fluid in the direction of a fluid flow flowing from the upstream compartment 44 to the downstream compartment 46.

(36) The piston 42 is full, so that the two compartments 44, 46 cannot communicate fluidly through the piston 42, but can communicate fluidly only via the flow limiter 50, through the orifices 84, 86.

(37) More particularly, and with reference to FIG. 8, the flow limiter 50 comprises a first pipe 51 and a second pipe 52 in parallel and providing the fluid connection between the two compartments 44, 46. This flow limiter 50 is equipped with:

(38) an adjustable or non-adjustable throttle valve 54 placed on the first pipe 51, this throttle valve 54 forming a variable or non-variable fluid restriction;

(39) a pressure regulator 56 placed on the first pipe 51 having its inlet in direct connection with the downstream compartment 46 and having its outlet in direct connection with the throttle valve 54; and

(40) a check valve 58 placed on the second pipe 52, this check valve 58 inhibiting the circulation of the fluid in this second pipe 52 in the direction of a fluid flow from the downstream compartment 46 to the upstream compartment 44.

(41) The flow limiter 50 is adjusted so that, when the cowl 20 is unlocked (as shown in FIG. 7) and when the actuator 24 is controlled to displace the rod 28 downstream in order to switch the cowl 20 from a position, the flow limiter 50 opposes the displacement of the fluid from the downstream compartment 46 to the upstream compartment 44, and thus opposes the relative displacement of the actuating rod 28 relative to the housing 32, and therefore relative to the cowl 20, to allow driving in displacement the assembly constituted by the cowl 20 and the nozzle 22.

(42) Conversely, when the cowl 20 is locked, the cylinder 24 drives the actuating rod 28 against the fluid displacements which damp the displacements of the rod 28, in order to allow driving in displacement the nozzle 22.

(43) Four sequences are possible with this thrust reverser 18.

(44) In a first sequence, it is desired to increase the outlet section of the nozzle 22, starting from a reduced section (illustrated in FIG. 4) or a neutral section (illustrated in FIG. 5), up to an increased section (illustrated in FIG. 6); the thrust reverser cowl 20 being located in the locked position relative to the fixed structure 12 of the aircraft turbojet engine nacelle, so that the housing 32 is fixed or static. In this first sequence, the actuator 24 is controlled in order to displace the actuating rod 28 upstream (direction of retraction of the rod 28, leftward in FIG. 4). During this displacement of the actuating rod 28, the piston 42 displaces the fluid contained in the upstream compartment 44 of the housing 32 in the direction of the downstream compartment 46 through the flow limiter 50. The fluid thus passes through the flow limiter 50 in its second pipe 52, via the check valve 58, and this flow limiter 50 enables, in this direction, a free circulation of the fluid. Thus, the actuating rod 28, secured to the piston 42, is displaced relative to the static housing 32 and it drives in displacement the flap 25 of the variable nozzle 22 to increase the outlet section of the nozzle 22.

(45) In a second sequence, it is desired to reduce the outlet section of the nozzle 22, starting from an increased section (illustrated in FIG. 6) or a neutral section (illustrated in FIG. 5) up to a reduced section (illustrated in FIG. 4); the thrust reverser cowl 20 being located in the locked position relative to the fixed structure 12 of the aircraft turbojet engine nacelle, so that the housing 32 is fixed or static. In this second sequence, the actuator 24 is controlled in order to displace the actuating rod 28 downstream (direction of deployment of the rod 28, rightward in FIG. 6) at a first given deployment speed. During this displacement of the actuating rod 28, the piston 42 displaces the fluid contained in the downstream compartment 46 of the housing 32 in the direction of the upstream compartment 44 through the flow limiter 50. The fluid does not circulate in the second pipe 52 because of the check valve 58 and passes through the pressure regulator 56 then the throttle valve 54. Since this first deployment speed is relatively low and since the housing 32 is static, the piston 42 is displaced downstream and forces the fluid towards the upstream compartment 44 of the housing 32, so that the actuating rod 28, secured to the piston, drives in displacement the flap 25 of variable nozzle 22 to reduce the outlet section of the nozzle 22.

(46) In a third sequence, it is desired to actuate the thrust reverser cowl 20 in order to switch it from the direct jet position (illustrated in FIGS. 2 and 4) to the reverse jet position (illustrated in FIG. 7). First of all, the thrust reverser cowl 20 is unlocked from the fixed structure 12 of the aircraft turbojet engine nacelle 10. Thus, the thrust reverser cowl 20, and therefore the housing 32, are free to be displaced downstream. At the beginning of this third sequence, the nozzle 22 is in the increased ejection section position (as shown in FIG. 6) and therefore the piston 42 is substantially in abutment against the upstream wall 36 of the housing 32. Then, the actuator 24 is controlled in order to displace the actuating rod 28 downstream (direction of deployment of the rod 28, rightward in FIGS. 2 and 6) at a second given deployment speed relatively high relative to the aforementioned first deployment speed. The piston 42 exerts a thrust on the fluid contained in the downstream compartment 46 of the housing 32 in the direction of the flow rite limiter 50. The fluid does not circulate in the second pipe 52 because of the check valve 58, and engages in the first pipe 51 to pass through the pressure regulator 56 then the throttle valve 54. With such a second displacement speed of the actuating rod 28, and therefore of the piston 42, the throttle valve 54 limits the fluid circulation rate and thus limits the passage of the fluid in the direction of the upstream compartment 44. Thus, the flow limiter 50 inhibits the relative displacement of the piston 42 relative to the housing 32. Consequently, the relative displacement of the actuating rod 28 relative to the thrust reverser cowl 20 is also inhibited, which inhibits any pivoting of the nozzle 25. The housing 32 transmits, in turn, the translation movement of the actuating rod 28 to the thrust reverser cowl 20, driving then the switching of the cowl 20 from a direct jet position to a reverse jet position. Finally, it is possible to reduce the section of the nozzle 22 by substantially following the aforementioned second sequence, in other words by deploying the rod 28 according to the first deployment speed.

(47) In a fourth sequence, it is desired to actuate the thrust reverser cowl 20 in order to switch it from the reverse jet position (illustrated in FIG. 7) to the direct jet position (illustrated in FIGS. 2 and 4). The actuator 24 is controlled in order to displace the actuating rod 28 upstream (direction of retraction of the rod 28, leftward in FIG. 7). At the beginning of this fourth sequence, the nozzle 22 is in the increased ejection section position (as shown in FIG. 7) and therefore the piston 42 is substantially in abutment against the upstream wall 36 of the housing 32. Thus, during this displacement of the actuating rod 28, the piston 42 remains in abutment against this upstream wall 36 and the fluid undergoes no displacement, so that the actuating rod 28, secured to the piston 42, drives the cowl 20 directly towards the direct jet position, this cowl being in the end locked. Finally, it suffices to reduce the outlet section of the nozzle 20 by following the aforementioned second sequence.

(48) The deployment speeds of the actuators 24 in the second sequence are extremely low vis--vis the speeds in the third sequence. The present disclosure therefore proposes to use the viscous property of fluids, which tends to facilitate the flow at low speed (second sequence) and to limit it at high speed (third sequence). The flow limiter 50 thus acts passively depending on the deployment speed of the actuators 24, to allow the aforementioned different sequences. The housing 32 is of simple and compact construction and proposes, with the flow limiter 50, a passive operation; the flow limiter 50 allowing to easily accommodate the sudden variations of pressure in the housing 32.

(49) According to another aspect, the actuating rod 28 includes a first segment 62 which is slidably mounted in the body 26 of the cylinder 24 and also slidably mounted in the housing 32 of the coupler 30, and a second segment 64 which is hinged on the flap 25 of the nozzle 22. As seen in FIGS. 4, 5 and 7, the first segment 62 and the second segment 64 are linked together by a mechanical connection 66 which, possibly, allows a noticeable offset and an uncoupling of the first segment 62 and of the second segment 64 of the actuating rod 28. This mechanical connection 66 can allow dissociating the first segment 64 from the second segment 66 of the actuating rod 28 during the opening of the cowl 20 in the maintenance configuration.

(50) The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.