Abstract:
A thrust reverser for a turbojet engine nacelle includes a movable cowl, cascade vanes and a portion forming a movable variable nozzle. The cowl translates between a closing position and a maintenance position which is located beyond a thrust reversal position. In the maintenance position, the cowl opens a passage within the nacelle and allows access the inside of the nacelle. The variable nozzle is translated by an actuator between reduced ejection section and increased section positions. In particular, the cascade vanes move between retracted and active positions and are housed in an envelope formed by a fan casing and an outer cowl in the retracted position. In the active position, the cascade vanes are displaced downstream by an actuator through a passage open by the movable cowl in the nacelle. The actuator of the cascade vanes is dissociable from the actuator driving the variable nozzle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/FR2013/051339, filed on Jun. 10, 2013, which claims the benefit of FR 12/55508, filed on Jun. 12, 2012. The disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a thrust reverser for a turbojet engine nacelle. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     An aircraft is driven by several turbojet engines each housed in a nacelle accommodating an assembly of annex actuating devices related to its operation and providing various functions when the turbojet engine is in operation or at shutdown. 
     These annex actuating devices comprise in particular a thrust reversal mechanical system. 
     A turbojet engine nacelle generally has a substantially tubular structure comprising an air inlet upstream of the turbojet engine, a mid-section intended to surround a fan of said turbojet engine, a downstream section intended to surround the combustion chamber of the turbojet engine and optionally integrating thrust reversing means, and is generally terminated with an ejection nozzle the outlet of which is located downstream of the turbojet engine. 
     Modern nacelles are intended to accommodate a bypass turbojet engine capable of generating via the blades of the rotating fan a hot air flow (primary flow) and a cold air flow (secondary flow) which circulates outside the turbojet engine through an annular passage, also called flow path, formed between a fairing of the turbojet engine and an inner wall of the nacelle. The two air flows are ejected from the turbojet engine from the rear of the nacelle. 
     The role of a thrust reverser, during the landing of an aircraft, is to improve the braking ability thereof by redirecting forward at least a part of the air ejected from the turbojet engine. In this phase, the thrust reverser obstructs at least a part of the flow path of the cold flow and directs this flow to the front of the nacelle, therefore generating a counter-thrust which adds to the braking of the wheels and air brakes of the aircraft. 
     In general, the structure of a thrust reverser comprises a thrust reverser cowl displaceable between, on the one hand, a deployed position in which it opens a passage within the nacelle intended for the diverted air flow, and on the other hand, a retracted position in which it closes this passage. 
     In the case of a cascade-type thrust reverser, the reorientation of the air flow is performed by cascade vanes, associated with reversing flaps that block at least partially the air circulation flow path, the cowl having only a simple sliding function aiming to uncover or cover these cascade vanes. 
     The reversing flaps, also called blocking flaps, in turn, are activated and driven by slide of the movable cowl until obstructing at least partially the flow path downstream of the cascade vanes, so as to optimize reorientation of the cold air flow. 
     As is known, the cascade vanes are mounted on a front frame serving as a fixed portion of the thrust reversal device and fastened to a casing of the fan of the turbojet engine. This front frame also provides the support of actuating cylinders of the movable cowls. 
     Most often, the downstream section of the nacelle is made of two substantially semi-cylindrical semi-structures located, at the upper portion (called 12 hours), on both sides of an engine pylon of fastening of the turbojet engine to the aircraft and connected therebetween at the lower portion (called 6 hours). 
     The semi-structures are fastened to the engine pylon via an upper half-beam, and also comprise a lower half-beam. These lower and upper half-beams are equipped with slide rails for the thrust reversal movable cowl of the corresponding semi-structure. 
     For maintenance purposes, these semi-structures are pivotally mounted on the engine pylon about an axis substantially longitudinal of the nacelle via hinges. Latches at the lower portions provide the closing of the structure. 
     A nacelle having such a downstream structure having semi-cylindrical cowlings is commonly referred to as nacelle with a C or D duct (C-Duct or D-Duct). 
     Have also been developed nacelles called with an O structure (O-Duct) having a downstream structure that no longer exhibit two substantially semi-cylindrical semi-structures but one single substantially peripheral structure extending from one side of the engine pylon to the other side. 
     As a result, such a structure generally no longer exhibits two thrust reversal movable cowls but one single substantially peripheral cowl. 
     For maintenance purposes, such a downstream section no longer opens by the pivoting of the semi-structure about a substantially longitudinal axis of the nacelle but by downstream translation along this axis. 
     For a detailed description, one may refer to documents FR 2 911 372 and FR 2 952 681. 
     It will be noted in particular that for the purposes of the operations of maintenance and access to the combustion chamber of the turbojet engine, the front frame supporting the cascade vanes may in turn be disconnectable and moved backward with the outer cowling. 
     Furthermore, there are known called short O-Duct nacelle structures, in which the cascade vanes are also movably mounted in translation and able to be retracted at least partially along the thickness of the mid-section of the nacelle and thus overlap the fan casing when the thrust reverser is inactive, in the direct jet position. In the thrust reversal position, the cascade vanes are displaced with the movable cowl. The cascade vanes are hence no longer totally housed inside the movable cowl and thus occupy a less significant space which allows shortening it. 
     Besides a thrust reversal function, a reverser movable cowl belongs to the rear section and may exhibit a downstream portion forming an ejection nozzle. 
     The section of the ejection nozzle may be adapted depending on the different flight phases, namely, in particular, take-off, ascent, cruise, descent and landing in order to always preserve an optimal nozzle section depending on the turbojet engine speed. The nozzle will be then called variable nozzle. 
     Such a variable nozzle is associated with an actuating system allowing this section variation. 
     There are several solutions for realizing a variable nozzle. 
     A first solution is to provide pivoting terminal flaps mounted on the thrust reversal movable cowl and the pivoting of which is reflected in an increase or in a reduction of the outlet section. Such a system is described in particular in document FR 2 929 998. 
     There are also known panels movably mounted in translation inside the thrust reversal movable cowl, in a telescopic manner, the backward motion or the retraction of which similarly cause the increase or the reduction of the outlet section. 
     In such cases, the variable nozzle device has a dedicated actuating system, or a double-acting actuating system also associated with the reversal movable cowl. 
     Such solutions allow better accommodating the inner and outer aerodynamic lines of the nacelle and allow a better structural strength of the assembly. 
     In order to simplify the actuating systems and lighten the nacelle, another solution may also be envisaged thanks to the substantially conical shape of the back of the body of the nacelle: the thrust reversal movable cowl also provides by itself a variable nozzle function. The operation principle of such an arrangement is described in the document U.S. Pat. No. 5,655,360. 
     Although such an arrangement allows substantially lightening the rear section, its design involves some difficulties. 
     Indeed, during the displacement of the movable cowl in the nozzle mode, it should be provided that this displacement does not cause opening of the thrust reversing passage in the nacelle. Moreover, the movable cowl could be retracted in order to allow reducing the nozzle section relative to a nominal position. 
     This requires an overlay area at a rear end of the mid-section, an overlay area which generates an undesirable external aerodynamic accident. 
     Moreover, in the case of a thrust reversal system with retractable cascade vanes, a displacement of the movable cowl normally causes the concomitant displacement of the cascade vanes, or the displacement of said cascade vanes is useless during a displacement of the cowl in the nozzle mode. 
     Furthermore, the existing solutions may hardly be integrated with an O-Duct type nacelle with a peripheral thrust reverser cowl and this, either because of the installation of rails between the thrust reverser movable cowl and the outer structure which may be translated for maintenance purposes, or because of the complexity of the compatibility with the need to translate the assembly for accessing the engine compartment. 
     SUMMARY 
     The present disclosure provides a thrust reverser for turbojet engine nacelle comprising at least one cowl movable in translation along a direction substantially parallel to a longitudinal axis of the nacelle between a closing position in which it provides the aerodynamic continuity of the nacelle and inhibits diverting means, and a fully opening maintenance position, located beyond a thrust reversal position, in which it opens a passage in the nacelle and allows accessing the inside of the latter, said movable cowl being further extended by at least one portion forming a movable variable nozzle associated with at least one means for driving in translation along a substantially longitudinal direction of the nacelle between a reduced ejection section position and an increased section position, characterized in that the diverting means are movably mounted longitudinally between a retracted position upstream of the movable cowl in which they may be housed inside an envelope of the nacelle comprised between a fan casing and an outer cowl of the nacelle, and an active position in which they are displaced downstream so as to be capable of extending through an open passage by the movable cowl in the nacelle, and in that said diverting means are associated with at least one actuator dissociable from the actuator of the variable nozzle. 
     Thus, by providing diverting means that are movable and able to be driven in a disassociated manner from the portion forming a variable nozzle, the thrust reversal device is capable of adopting multiple configurations, thus satisfying the needs for displacing the movable portions in the thrust reversal mode as well as in the maintenance mode. 
     According to a first form, the portion forming a variable nozzle is integrated to the movable cowl, the whole exhibiting a one-piece nature. 
     According to a second form, the portion forming a variable nozzle is movably mounted relative to the movable cowl, the latter being further equipped with disconnectable attaching means with said portion forming a variable nozzle. 
     The disconnectable attaching means allow either a driving of the variable nozzle alone (disconnected means; variable nozzle mode), or a joint driving of the thrust reverser movable cowl and of the nozzle (locked means, maintenance mode or thrust reversal mode). 
     Advantageously, the diverting means are equipped with disconnectable attaching means with the movable cowl. 
     The movable cowl is further equipped with disconnectable attaching means with the portion forming a variable nozzle. 
     According to one feature of the present disclosure, the attaching means between the diverting means and the movable cowl are adapted to collaborate with a locking device arranged between the diverting means and a fixed structure of said thrust reverser or said nacelle. 
     According to another feature of the thrust reverser according to the present disclosure, the attaching means between the movable cowl and the portion forming a variable nozzle are adapted to collaborate with a locking device arranged between the diverting means and a fixed structure of said thrust reverser or of said nacelle. 
     In an alternative or complementary manner, the diverting means are associated with at least one dedicated actuator. Such a dedicated actuator also constitutes an actuator dissociable from that of the nozzle to the extent that it allows an in-phase (associated) driving or a different (disassociated) driving. 
     According to another form, the diverting means comprises cascade vanes. 
     Advantageously, the thrust reverser is a thrust reverser of the type called O-Duct type. 
     The present disclosure also relates to a turbojet engine nacelle, characterized in that it is equipped with at least one thrust reverser according to the present disclosure. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       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: 
         FIG. 1  is a perspective representation of a turbojet engine nacelle with an O-type duct and with a thrust reverser with retractable cascade vanes; 
         FIGS. 2 a , 2 b , 2 c    are representations in different configurations of a first form of the present disclosure; 
         FIGS. 3 a , 3 b , 3 c , 3 d    are representations in different configurations of a second form of the present disclosure; 
         FIGS. 4 a , 4 b , 4 c    are representations in different configurations of a third form of the present disclosure; 
         FIGS. 5 a  to 5 h    represent the different steps for locking and attaching the movable portions of the nacelle according to a third form; and 
         FIGS. 6 a , 6 b , 6 c    are representations in different configurations of a fourth form of the present disclosure. 
     
    
    
     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 
     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. 
       FIG. 1  is a general representation of a turbojet engine nacelle  1  with an O-type duct and equipped with a thrust reversal device. 
     This nacelle  1  is intended to hang from an engine pylon (not visible) via a fixation block  2  serving as a connecting interface. 
     It conventionally comprises an air inlet upstream section  3 , a mid-section  5  (not visible in  FIG. 1 ) intended to surround a casing  4  of a fan of the turbojet engine, and a downstream section  7  equipped with the thrust reversal device. 
     As described above, the thrust reversal device comprises a substantially peripheral cowl  10  extending on both sides of the engine pylon, and an assembly of cascade vanes  11 . 
     The cascade vanes  11  are movably mounted in translation along a substantially longitudinal direction of the nacelle  1  between a retracted position in which they are stored at least partially along the thickness of the mid-section  5  upstream of the downstream section and overlap at least partially the fan casing  4 ; and a deployed position in which they extend downstream of the mid-section  5  at the downstream section. 
     The cowl  10  is movably mounted in translation along a direction substantially parallel to a longitudinal axis of the nacelle  1  between several positions:
         A first position corresponding to a closing position (also called direct jet position) and in which it provides the aerodynamic continuity of the nacelle  1 . In this position, the cascade vanes  11  are in the retracted position.   A second position, called thrust reversal position, in which the cowl  10  is moved backward and opens a reversing passage in the nacelle  1 . In this position, the cascade vanes  11  are moved backward and reorient the air flow traveling through the passage.   A third position, called maintenance position, in which the movable cowl  10  is moved fully backward and opens a significant passage in the nacelle so as to allow accessing the inside of the latter.       

     The present disclosure provides a nacelle as precedingly described and in addition equipped with a variable nozzle device comprising a portion forming a movable variable nozzle associated with at least one means for driving in translation between at least one reduced ejection section position and/or one increased section position. 
       FIGS. 2 a  to 2 c    show a nacelle  100  according to a first form of the present disclosure. 
     In this form, the variable nozzle is constituted by a terminal portion  10   a  of the movable cowl with which it is integral. The nozzle variation is hence performed by displacing the cowl  10  and nozzle portion  10   a  assembly the required distance for obtaining the desired section. 
     According to this form, each movable portion is able to be driven by dedicated actuator allowing to choose between a disassociated or an associated driving of said movable portions, or even a totally independent driving. 
     More precisely, as precedingly explained, the cascade vanes  11  constitute a first movable portion which is able to be driven in translation by a first assembly of actuating cylinders  12 . 
     The movable cowl  10  and its portion forming a movable nozzle  10   a  together constitute a second movable portion able to be driven in translation by a second assembly of actuating cylinders  13 . 
       FIG. 2 a    shows the nacelle  100  in the direct jet configuration, with the movable cowl  10  closed and the cascade vanes  11  retracted. The nozzle section variation is obtained by slight displacements around the closing position of the movable cowl  10  by means of the cylinders  13 . 
       FIG. 2 b    shows the nacelle  100  in the thrust reversing position. The cylinders  13  have pushed the movable cowl  10  in its reversing position, and the cylinders  12  have deployed the cascade vanes  11  across the opening made by the displacement of the movable cowl  10  in the nacelle  100 . 
       FIG. 2 c    shows the nacelle  100  in the maintenance position. The cascade vanes  11  are retracted and the cylinders  13  have pushed the movable cowl  10  downstream in the fully backward position. The opening arranged in the nacelle  100  is then large enough to allow accessing the inside of the latter. 
       FIGS. 3 a  to 3 d    show a nacelle  200  according to a second form of the present disclosure. 
     In this form, the variable nozzle is constituted by a terminal portion  10   a  of the movable cowl which is movably mounted in a telescopic manner inside the movable cowl  10 , the latter constituting an intermediate structure. 
     In this form, there are hence three movable portions, namely the cascade vanes  11 , the thrust reversal movable cowl  10  and the variable nozzle portion  10   a.    
     The nozzle variation is hence performed by displacing the variable nozzle portion  10   a  alone, the thrust reversal movable cowl  10  remaining in the closing position, integral with the cascade vanes  11 . The displacement of the variable nozzle portion  10   a  is performed by means of an assembly of second actuators  131 . 
     As with the nacelle  100 , the cascade vanes  11  are driven via an assembly of dedicated first actuating cylinders  12  allowing to choose between a driving of said cascade vanes disassociated or associated with that of the variable nozzle  10   a.    
     The cascade vanes  11  and the thrust reversal movable cowl  10  are equipped with latch-type disconnectable attaching means. 
       FIG. 3 a    shows the nacelle  200  in the direct jet configuration, with the movable cowl  10  closed and integral with the cascade vanes  11 , these cascade vanes  11  being in the retracted position. 
     The nozzle section variation is obtained by autonomously displacing the nozzle portion  10   a  alone around its reference position by means of the actuators  131  ( FIG. 3 b   : increase of the ejection section by moving the nozzle portion  10   a  backward). 
       FIG. 3 c    shows the nacelle  200  in the thrust reversal position. In this phase, the movable cowl  10  is still connected to the cascade vanes  11 . The actuators  131  have pushed the variable nozzle portion  10   a  and the cylinders  12  have deployed the cascade vanes  11  across the opening made by the displacement of the movable cowl  10  in the nacelle  200 . 
       FIG. 3 d    shows the nacelle  200  in the maintenance position. In this phase, the movable cowl  10  is disconnected from the cascade vanes  11 . The cascade vanes  11  are retracted and the actuators  131  have pushed the nozzle portion  10   a  with the movable cowl  10  downstream in the fully backward position. The driving of the movable cowl is made possible thanks to an end-of-travel abutment provided between said movable cowl  10  and the nozzle portion  10   a  which has allowed driving said cowl. Alternatively, a pin-type mechanical connection may be manually positioned between the movable cowl  10  and the nozzle  10   a  in order to attach their motion only for the maintenance phase. 
     The opening arranged in the nacelle  200  is then large enough to allow accessing the inside of the latter. 
       FIGS. 4 a  to 4 c    show a nacelle  300  according to a third form of the present disclosure. 
     In this form, the variable nozzle is constituted, as with the nacelle  100 , by a terminal portion  10   a  of the movable cowl with which it is integral. The nozzle variation is hence performed by displacing the cowl  10  and portion nozzle  10   a  assembly the required distance for obtaining the desired section. 
     Yet, unlike the nacelle  1 , the two movable assemblies, namely the cascade vanes  11  and the cowl  10 /nozzle  10   a  assembly, each no longer have their dedicated actuating means, but are driven by means of one single assembly of actuators  132  connected to the cowl  10 /nozzle  10   a  assembly. 
     The dissociable driving between the cascade vanes  11  and the cowl  10 /nozzle  10   a  assembly is performed via disconnectable locking devices between the cascade vanes  11  and the movable cowl  10 . The locking devices are generally in the form of U-shaped elements that engage a bolt to prevent movement of the cascade vanes. 
     When these locking devices are disconnected, the actuators  132  allow driving the cowl  10 /nozzle  10   a  assembly in the nozzle  10   a  section variation mode or in the maintenance mode ( FIGS. 4 a  and 4 c    respectively). 
     When these locking devices are connected, they provide the attaching of the cowl  10  and the cascade vanes  11 , and the actuators  132  then allow driving the cowl  10 /nozzle  10   a  assembly and the cascade vanes  11  in the thrust reversal mode ( FIG. 4 b   ). 
     An example of the different steps of locking and attaching the different movable portions of the nacelle  300  is represented in  FIGS. 5 a    to  5   h.    
     In  FIG. 5 a   , the cowl  10 /nozzle  10   a  assembly is closed. The locking device  50  between the cascade vanes  11  and the movable cowl  10  is disconnected and moved away from the corresponding bolt  53  carried by the cascade vanes  11 . 
     The cascade vanes  11  are retracted inside the mid-section, and are retained in position by another locking device  40  blocked by a locking blade  41  and engaged with a corresponding bolt  43  carried by the cascade vanes  11 , a conventional locking system known to those skilled in the art and allowing the non-opening of the thrust reverser in flight by locking the cascade vanes  11  with the fan casing  4  or any other fixed portion of the nacelle  300 . 
       FIG. 5 b    shows a configuration in which the movable cowl  10 /nozzle  10   a  assembly has slightly moved backward to increase the nozzle section  10   a  (variable nozzle mode). In such a configuration, the cascade vanes  11  remain locked in the retracted position. The cowl  10 /nozzle  10   a  assembly is displaced between its previous totally closed position and before its thrust reversal backward position. 
     In  FIG. 5 c   , the cowl  10 /nozzle  10   a  assembly has moved backward enough and switches in the thrust reversal mode. To do so, the locking device  50  engages the corresponding bolt  53 , which causes attaching of the cascade vanes  11  and of the cowl  10  ( FIG. 5 d   ). A spring leaf  51  blocks the locking device  50  in the locked position. 
     As represented in  FIGS. 5 e  and 5 f   , once the cascade vanes  11  are attached with the movable cowl  10 , they are unlocked upstream of their retracted position. 
     The bolt  43  being thus released, the cascade vanes  11  are driven downstream in translation with the cowl  10  by the actuators  132  ( FIG. 5 g   ). 
       FIG. 5 h    illustrates the configuration of the locking device for an operation in the maintenance mode. 
     In this operating mode, the cascade vanes  11  remain in the retracted position and locked upstream by the other locking device  40 . 
     The locking device  50  of the movable cowl tilts around the corresponding bolt  53  in order to allow the additional translation of the cowl  10 /nozzle  10   a  assembly toward the downstream maintenance position. 
     To do so, the spring leaf  51  for blocking the locking device  50  is kept away by a tool or a member  54 . The backward motion is free. 
       FIGS. 6 a  to 6 c    show a nacelle  400  according to a fourth form of the present disclosure. 
     In this form, the variable nozzle is constituted, as with the nacelle  200 , by a terminal portion  10   a  of the movable cowl which is movably mounted in a telescopic manner inside the movable cowl  10 , the latter constituting an intermediate structure. 
     In this form, there are thus three movable portions, namely the cascade vanes  11 , the thrust reversal movable cowl  10  and the variable nozzle portion  10   a.    
     The nozzle variation is hence performed by displacing the variable nozzle portion  10   a  alone, the thrust reversal movable cowl  10  remaining in the closing position. The displacement of the variable nozzle portion  10   a  is performed by means of an assembly of actuators  133 . 
     Unlike the nacelle  200 , the nacelle  400  is equipped with only one assembly of actuators  133  connected to the nozzle  10   a.    
     The dissociable driving between the cascade vanes  11 , the movable cowl  10  and the nozzle is performed via a disconnectable locking device between, on the one hand, the cascade vanes  11  and the movable cowl  10 , and on the other hand, between the movable cowl  10  and the nozzle  10   a , as with the nacelle  200 . 
     When the locking device between the movable cowl  10  and the nozzle  10   a  is disconnected, the actuators  133  allow actuating the nozzle portion  10   a  alone in the nozzle section  10   a  variation mode ( FIG. 6 a   ). The operation of this locking device is identical to that described above for the nacelle  300 . 
     During an operation in the thrust reversal mode, the locking device between the cowl  10  and the nozzle  10   a  is connected, as well as those between the cowl  10  and the cascade vanes  11  ( FIG. 6 b   ). 
     Finally, during an operation in the maintenance mode, the locking device between the cascade vanes  11  and the cowl  10  is manually disconnected whereas the cowl  10  remains connected to the nozzle  10   a  ( FIG. 6 c   ). 
     Although the present disclosure has been described with a particular form, it is obvious that it is in no way limited thereto and that it comprises all technical equivalents of the described means as well as their combinations if they are within the scope of the present disclosure.