Abstract:
A thrust reverser of a turbofan pod is provided that includes movable cowlings that retract relative to stationary front structure to reveal stationary or movable thrust reverser cascades, as well as a secondary variable nozzle section connected to the movable cowlings by guiding means enabling movement controlled by actuators engaged with the front structure to apply an axial thrust. The actuators are directly connected to the secondary nozzle, and in that the thrust reverser comprises latches connected to the movable cowlings, having two positions providing, alternately, latching onto the front structure or latching onto the control of the secondary nozzle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/FR2015/050777, filed on Mar. 26, 2015, which claims the benefit of FR 14/53266, filed on Apr. 11, 2014. The disclosures of the above applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure concerns a thrust reverser for an aircraft nacelle accommodating a turbojet engine, as well as an aircraft nacelle equipped with such a thrust reverser. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    The motorization assemblies for aircrafts generally include a nacelle forming a generally circular outer shell, comprising in the interior a turbojet engine disposed along the longitudinal axis of this nacelle. The turbojet engine receives fresh air coming from the upstream or front side, and rejects from the downstream or back side the hot gases resulting from the combustion of the fuel, which provide some thrust. 
         [0005]    The bypass turbojet engines present, around this turbojet engine, fan blades generating an important secondary flow of cold air along an annular flow path passing between the engine and the nacelle, which adds a high thrust. 
         [0006]    Some nacelles include a thrust reverser system which closes at least partially the annular flow path of cold air, and rejects the secondary flow forward in order to generate a braking thrust of the aircraft. 
         [0007]    A known type of thrust reverser, presented in particular in the document FR-A1-2758161, includes rear movable cowls called “Trans-cowl,” sliding axially rearward under the effect of cylinders by deploying flaps in the annular flow path in order to close for the most part this flow path. The flaps return the cold air flow radially outward by passing through cascade vanes uncovered by the movable cowls during their sliding movements, comprising blades which direct this flow forward. 
         [0008]    Furthermore, some nacelles include a secondary rear nozzle called “Variable Fan Nozzle” (VFN), providing a secondary variable flow thanks to a translational movement of this nozzle which is connected to the movable cowls of the thrust reverser by guide means allowing an axial movement of the control system. 
         [0009]    An actuation system known to the thrust reverser as well as to the variable secondary nozzle, include cylinders fixed on one side to the front fixed structure and on the other side to the secondary nozzle disposed at the rear, these cylinders pass through the entire structure of the movable cowls of the thrust reverser located axially between these two portions. The nacelle also includes two independent controlled locks, a fixed lock linking the front structure to the cowls, and a movable lock linking these cowls to the secondary nozzle. 
         [0010]    By actuating the cylinders rearward, only a decrease of the secondary nozzle is obtained if the movable lock is open and the fixed lock is closed, and a deployment of the thrust reverser together with the nozzle if, conversely, the fixed lock is open and the movable lock is closed. 
         [0011]    A problem which arises with this actuation system is that, for controlling the movable cowls, the axial thrust reversers developed by the cylinders are directly applied to the secondary nozzle disposed rearward, which then transmits these forces forward to the movable cowls by the movable lock. It is then necessary to size the secondary nozzle in order to transmit these constraints, thereby forcing to provide for additional masses. 
       SUMMARY 
       [0012]    The present disclosure provides a thrust reverser of a bypass turbo engine nacelle, comprising movable cowls which move backwards relative to a front fixed structure in order to uncover fixed or movable cascade vanes of thrust reverser, as well as a variable secondary nozzle connected to the movable cowls by guide means allowing a controlled displacement by cylinders bearing on the front structure in order to apply an axial thrust, characterized in that the cylinders are directly connected to the secondary nozzle, and in that the thrust reverser includes locks linked to the movable cowls, comprising two positions causing alternately a blocking on the front structure or a blocking on the control of the secondary nozzle. 
         [0013]    An advantage of this thrust reverser is that, for actuating the cowls, the forces developed by the cylinders are transmitted directly to these cowls by passing through the locks in the position causing the blocking on the control of the secondary nozzle, which avoids making the constraints pass in this nozzle. 
         [0014]    Moreover, the locks comprising only two positions, are simple to control by a single actuator providing these two positions. 
         [0015]    The thrust reverser according to the present disclosure may further include one or more of the following feature(s), which can be combined together. 
         [0016]    According to one form, the locks are tilting in order to take their two positions, which represents a simple construction mode. 
         [0017]    The locks positioned on the movable cowl can be controlled from the front fixed structure. 
         [0018]    In particular, each titling lock may include a central pivot linked to the movable cowls, and axially on either side, an attachment device which can be fixed, one to the front structure and the other to the control of the secondary nozzle. 
         [0019]    According to another form, the locks are mounted on an axis pivoting by about 90° to take their two positions, which represents a second simple construction mode. 
         [0020]    In particular, each lock may include an axis disposed longitudinally in the nacelle, guided in rotation by an element linked to the movable cowls, including at each end, attachment device that can be fixed, alternately, one to the front structure and the other to the control of the secondary nozzle. 
         [0021]    Advantageously, the thrust reverser includes a movable part forming safety which keeps the blocking of the lock in each position. Safety is then provided in a simple manner by avoiding a release of the blocking. 
         [0022]    The movable safety part can be a drawer guided by an element linked to the movable cowls, including a sliding movement for blocking the lock alternately in one of its two positions. 
         [0023]    In this case, the movable safety part is advantageously controlled by the actuator which moves the lock, a clearance being interposed between this actuator and this lock in order to allow a displacement of the movable part before moving the lock. Thus, a simple kinematics which avoids risks of blocking the operation is carried out. 
         [0024]    Advantageously, the blocking devices include resilient return means providing two blocking and unblocking stable positions. These resilient means allow in a simple and inexpensive manner to ensure these stable positions. 
         [0025]    Optionally, the locks positioned on the movable cowl can be controlled from the front fixed structure and lock only the variable secondary nozzle relative to the movable cowl. 
         [0026]    The present disclosure also provides a turbojet engine nacelle including a thrust reverser comprising any one of the preceding features. 
         [0027]    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 
         [0028]    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: 
           [0029]      FIGS. 1   a,    1   b  and  1   c  are diagrams in axial section of a thrust reverser according to the present disclosure, presented successively in closed position with the retracted then deployed secondary nozzle, and in open position; 
           [0030]      FIGS. 2 a , 2 b , 2 c , 2 d  and 2 e    are views of a tilting lock for this thrust reverser, presented successively, with a blocking on the front structure, the nozzle being retracted then deployed, during the tilting of the blocking, and with a blocking on the cylinder, the cowls being closed then open; and 
           [0031]      FIGS. 3 a , 3 b , 3 c  and 3 d    are views of a rotary lock for this thrust reverser, presented successively with a blocking on the front structure, the nozzle being retracted then deployed, during rotation, and with a blocking on the cylinder, the cowls being open. 
       
    
    
       [0032]    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 
       [0033]    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. 
         [0034]      FIG. 1  shows the rear portion of a jet engine nacelle, the rear axial direction being indicated by the arrow “AR”, comprising a front fixed structure  2 , and movable cowls  4  fitted rearward of this structure. 
         [0035]    Each cowl  4  is connected to the front structure  2  by longitudinal guide means, which allow a rearward sliding of these cowls in order to open the passage of the secondary flow radially outward, and to lower flaps  6  closing the outlet rearward, and returning the flow toward these passages comprising non represented thrust reverser cascade vanes. 
         [0036]    A secondary nozzle  8  disposed at the rear of the nacelle, is connected to the cowls  4  by axial guide rails allowing a position retracted forward shown in  FIG. 1   a,  and a position deployed rearward shown in  FIG. 1 b    which improves the yields for the high rotation speeds of the turbojet engine. 
         [0037]    Cylinders  10  axially disposed in the front structure  2  include a body fixed to this front structure, and a stem projecting rearward which is directly connected to the secondary nozzle  8  by an axial control rod  12  passing through the cowls  4  in their lengths. 
         [0038]    A tilting lock  14  linked by a central pivot to the cowls  4 , includes two blocking stable positions comprising alternately a front hook engaged on a front stud  18  fixed to the front structure  2 , or a rear hook engaged on a rear stud  16  fixed to the control rod  12 . 
         [0039]      FIGS. 1 a  and 1 b    show the tilting lock  14  with its engaged front hook, which links the flaps  4  to the front structure  2 . We can then control only the deployment of the nozzle  8 , with the decrease of the cylinder  10  as shown in  FIG. 1   b.    
         [0040]      FIG. 1 c    shows the tilting lock  14  with its rear hook engaged, which detaches the cowls  4  from the front structure  2  and fix them to the nozzle  8 . The actuation of the cylinder  10  then causes the decrease of the assembly formed by the flaps  4  and the nozzle  8 . 
         [0041]    Thus, a control of two different movements which improves the force paths is made with a simple and compact actuator in order not to apply unnecessary constraint on the elements. In particular, a weighted connection between the cylinder  10  and the variable nozzle  8  is obtained in direct flow mode, which allows controlling the stroke and the stops of the movements of this nozzle, as well as a direct connection between the cylinder and the movable structure of the thrust reverser. 
         [0042]      FIG. 2 a    shows a titling lock  14  which tilts about a pivot  24  perpendicular to the axis of the nacelle, fixed on an element  22  of the axially sliding structure with the movable flaps. 
         [0043]    The lock  14  lying along the axis of the nacelle, includes symmetrically on either side of its pivot  24 , a rear hook which can be engaged on a rear stud  16  as part of a fixation  20  connecting the end of the stem of the cylinder  10  to the control rod  12 , and a front hook which can alternately be engaged on a front stud  18  fixed to a support  26  linked to the front structure  2 . 
         [0044]    The lock  14  includes at its front end a tip projecting from the hook, which is engaged between two parallel arms  30  each mounted on a pivot  32  fixed on the support  26 , which are interconnected by a cross-member  38  mounted on joints in order to allow an inclination of these arms while maintaining their parallelism. 
         [0045]    One of the arms  30  includes at its pivot  32  a substantially perpendicular elbow  34 , terminating with a hinged connecting rod  36  which is connected to a drawer  44  guided both in the support  26  and in the element  22  linked to the movable flaps, in order to allow only a sliding movement along the axis of the nacelle without being able to laterally move away from the lock  14 . 
         [0046]    The arms  30  pivot under the effect of a non shown actuator performing a transverse movement according to the arrow “C”, in order to fix two stable end positions corresponding to the two blocking positions of the lock. This pivoting of the arms  30  causes a titling of the lock  14  comprising its engaged tip between these arms with a large clearance, as well as a sliding movement of the drawer  44  driven by the connecting rod  36 , which includes a front pad  40  and rear pad  42  directed toward each of the hooks corresponding to this lock. 
         [0047]    The operation of the lock is as follows. 
         [0048]      FIG. 2 a    shows the front hook engaged on the stud  18  of the front structure  2 , the axially guided drawer  44  having slid rearward so as to adjust its front pad  40  to the back of this hook, which prevents an accidental release from the hook which is thus locked on its stud. 
         [0049]    With the lock  14  held in this position,  FIG. 2 b    shows the cylinder  10  which deploys the secondary nozzle by a decrease of its stem driving the control rod  12  through the fixation  20 . The structure of the movable flaps remains securely attached to the front structure  2 , thanks to the drawer  44 , which maintains the position of the lock  14 . 
         [0050]    The cylinder  10  as well as the secondary nozzle being retracted,  FIG. 2 c    shows the arms  30  being pivoted under the effect of their actuator, starting by performing a forward sliding of the drawer  44  thereby unlocking the front hook of the lock  14  by the release of the front stud  40 . The clearance between the front tip of the lock  14  and the two arms  30  allow starting to pivot these arms as well as the sliding movement of the drawer  44 , before starting to tilt this lock. 
         [0051]      FIG. 2 d    shows the end of the tilting of the lock  14 , the rear pad  42  facing the rear hook, which locks the position comprising the detachment of the movable cowls from the front structure  2 , and their reattachments in a safety manner to the rod  12  controlling the nozzle. 
         [0052]    Then, as shown in  FIG. 2 e   , the cylinder  10  can be actuated to decrease both the movable flaps and the secondary nozzle. 
         [0053]    Advantageously, the lock  14  or its actuator include a non represented spring which, during a movement of the lock, is first compressed then expanded in order to provide two stable end positions corresponding to the two blocking positions of this lock. 
         [0054]      FIG. 3 a    shows the lock  50  formed by an axis disposed longitudinally in the nacelle, guided in rotation by an element  22  of the structure linked to the movable cowls, including at each end a front  52  or rear  56  transverse bar which are disposed perpendicularly relative to each other. 
         [0055]    The front bar  52  binds to the front structure  2  when it is vertical, by being engaged in upper and lower hooks  54  of this structure. Similarly, the rear bar  56  binds to the cylinder  10  when it is vertical by engaging in an upper hook  58  of the fixation  20 , this bar being also engaged in a lower hook  58  mounted on a slide  60  fixed on the movable cowls  4 . 
         [0056]    Thus, a 90° rotation of the axis of the lock  50  is carried out by putting a vertical bar to engage it in the two hooks on its side, a blocking of the movable cowls  4  with alternately the front structure  2  or the secondary nozzle  8 , the other horizontal bar can slide freely in front of the hooks corresponding to its side. 
         [0057]    The operation of the lock is as follows. 
         [0058]      FIG. 3 a    shows the axis of the lock  50  engaged on the hooks  52  of the front structure  2 , and released from the hook  58  linked to the cylinder  10 . Then, only the secondary nozzle  8  is operated as shown in  FIG. 3 b   , by leaving the movable cowls  4  fixed to the front structure  2 . 
         [0059]    The cylinder  10  as well as the secondary nozzle being retracted,  FIG. 3 c    shows the axis of the lock  50  pivoting under the effect of an actuator  62 , thereby releasing the front bar  52  from its hooks  54  and engaging the rear bar  56  in the hook  58  linked to the cylinder  10 . 
         [0060]    Then, the movable cowls  4  are detached from the front structure  2 , then, the assembly formed by these movable cowls and the secondary nozzle  8  is operated at the same time, as shown in  FIG. 3   d.