Abstract:
The invention relates to a bent connecting rod ( 31 ) for linking a first assembly to a second assembly which are movable relative to each other and through which a flow in the space defined thereby passes. The rod has at least one first and one second pivot point ( 35, 38 ) that are designed so as to enable the pivotal movement of the connecting rod ( 31 ) relative to said first and second assemblies, respectively, the bent connecting rod ( 31 ) being suitably positionable such that the bend ( 40 ) is located upstream from said flow relative to said second pivot point ( 38 ), said second pivot point ( 38 ) being suitably built into the second movable assembly, characterized in that the bent connecting rod ( 31 ) includes at least two portions ( 33, 37 ) linked together by at least one self-aligning means ( 39   a,    39   b ).

Description:
TECHNICAL FIELD 
     The present invention relates to a bent connecting rod intended to connect a first assembly to a second assembly which are moveable relatively to each other, equipped with at least one self-aligning means. 
     BACKGROUND 
     These are notably assemblies used in the aeronautical field, and in particular the downstream section of a secondary nozzle of an aircraft nacelle and the fixed internal structure of this nacelle. 
     An aircraft nacelle generally has a tubular structure comprising an air intake upstream from the turbine engine, a middle section intended to surround a fan of the turbine engine, a downstream section harboring thrust inversion means and intended to surround the combustion chamber of the turbine engine, and is generally terminated by an ejection nozzle, the outlet of which is located downstream from the turbine engine. 
     Modern nacelles are intended to harbor a ducted-fan turbine engine capable of generating via the blades of the rotating fan a hot air flow (also called a primary flow) stemming from the combustion chamber of the turbine engine, and a cold air flow (secondary flow) which circulates outside the turbine engine through an annular passage, also called a vein, formed between a fairing of the turbine engine, often designated as a fixed internal structure and an internal wall of the nacelle. Both air flows are ejected from the turbine engine through the rear of the nacelle. 
     The rear section of the nacelle has an ejection nozzle intended to channel the ejection of the airflows. This nozzle may come as an addition to a primary nozzle channeling the hot flow and is then called a secondary nozzle. 
     The role of a thrust inverter is, during the landing of an airplane, to improve the braking capability of the latter by redirecting forwards at least one portion of the thrust generated by the turbine engine. In this phase, the inverter obstructs the cold flow vein and directs the latter towards the front of the nacelle, consequently generating a counter thrust which will be added to the braking of the wheels of the airplane. 
     The means applied for achieving this reorientation of the cold flow vary according to the inverter type. However, in every case, the structure of an inverter comprises moveable displaceable elements between a deployed position in which they open in the nacelle a passage intended for the deflected flow on the one hand and a retracted position in which they close this passage on the other hand. These moveable elements may fulfil a deflection function or simply for activating other deflection means. 
     Moreover, in order to transform an overall rectilinear displacement into essentially a rotary movement by transmitting forces transmitted on the moveable element towards other elements, it is currently resorted to a connecting rod system. 
     For this purpose, it is known from the state of the art how to use straight connecting rods mainly consisting of a metal rod joining two joints with a moveable axis connected to the moveable elements. Such straight connecting rods are notably used in the downstream section of aircraft nacelles, equipped with thrust inverters, and more particularly for causing the inclination of a moveable panel from a substantially rectilinear displacement of the cowl on which it is rotatably attached. French application FR 08/04295 relates to such an arrangement with a straight connecting rod connecting a panel firmly attached to the secondary nozzle to the fixed fairing section of the turbine engine. 
     Such a straight connecting rod system is not always adapted to these nacelles equipped with thrust inverters. The presence of such connecting rods in the secondary flow considerably perturbs the aerodynamics and reduces the performances of the engine. Also, in order not to perturb the aerodynamics, it is known how to attach the connecting rod further upstream on the fixed internal structure. However, such a positioning upstream from the straight connecting rods is often unsuitable for allowing a displacement of the cowl which sufficiently exposes the deflection means, and by doing this ensuring the sought essentially vertical positioning of the moveable panel at the end of travel. 
     In order to fulfil aerodynamics on the one hand and therefore the presence of a connecting rod body positioned further upstream, and to keep the pivot point of the connecting rod on the fixed internal structure located further downstream, it is possible to resort to a bent connecting rod as illustrated in U.S. Pat. No. 4,533,098. 
     However, with such a bent connecting rod, during displacements of the cowl with the panel, the connecting rod is positioned in unstable and uncontrolled conformations which may cause its breaking or weakening of the surrounding structure. Such a phenomenon is amplified by the secondary airflow in the vein which induces strong vibrations of the connecting rod on its pivot points. 
     In order to stabilize the connecting rod, one of the possibilities is to embed one of the pivot points of the connecting rod. For this purpose, connecting rods with the pivot point of the connecting rod foot embedded into the fixed fairing structure of the turbine engine (or fixed internal structure) are known from application FR 08/06929. However such an arrangement is not very tolerant to changes in alignment of the parts, notably dealing with the alignment of the pivot points with the attachment points into which they are intended to be embedded. 
     BRIEF SUMMARY 
     In order to overcome the aforementioned drawbacks, the present invention relates, according to a first aspect, to a bent connecting rod, intended to connect a first assembly to a second assembly which are moveable relatively to each other and crossed by a flow in the space which they delimit, provided with at least one first and one second pivot points, designed so as to allow pivoting of the connecting rod relatively to said first and second assemblies respectively, the bent connecting rod being adapted so as to be positioned so that the bend is upstream from said flow relatively to said second pivot point, said second pivot point being adapted so as to be embedded into the second moveable assembly, characterized in that the bent connecting rod comprises at least two portions connected together through at least one self-aligning means. 
     With such an arrangement of a connecting rod with several portions, it is possible to reduce the stresses on the paths, notably at the pivot points on the fixed internal structure and on the secondary nozzle, given that impacts and vibrations are absorbed by at least one connecting point made from a self-aligning means. 
     The term of “self-aligning means” in the sense of the present invention defines an attachment point comprising an element giving some freedom of movement among the parts which it assembles, such as an element including at least one ball joint, designated as a &lt;&lt;ball-jointed element&gt;&gt;, or as an elastic assembly of the &lt;&lt;Paulstra™&gt;&gt; ring type. Thus, the parts connected by these points are moveable relatively to each other. The self-aligning means may for example have an essentially spherical structure, but may also have a mainly elongated configuration in order to maintain certain angles fixed among the parts of the connecting rod, such as to keep the angle of the bend of the connecting rod constant or for blocking the alignment between different portions of members. 
     According to other optional characteristics of the connecting device according to the present invention:
         the bent connecting rod comprises a first and a second portion connected together through at least one self-aligning means, said first portion being adapted so as to be connected to the first assembly through the first pivot point and said second portion being adapted so as to be connected to the second assembly through the second pivot point: such an assembly for example by means of ball joints directly inserted into the portions most likely to be sensitive to stresses, since they are connected through pivot points to the fixed internal structure and to the secondary nozzle, guarantees flexibility of the bent connecting rod by the absorption of stresses by the self-aligning means;   preferably, the second portion is embedded into the first portion and is maintained firmly attached to said first portion by two self-aligning means: such an arrangement is easy to achieve and is safe, it is possible to resort to spherical ball jointed elements such as those currently used in the field of aeronautics;   one of said portions is bent;   preferably, the adapted portion for being connected to the first assembly through the first pivot point is bent;   said self-aligning means are positioned between the second pivot point and the bend of the connecting rod;   the arrangement of said portions two by two is achieved through at least two self-alignment means as far away as possible from each other: such an arrangement gives the possibility of obtaining a maximum lever arm in order to reduce the torsion forces in the structure of the members bearing the self-aligning means;   the first pivot point crosses the profile of the body of the connecting rod substantially in the middle of the width of said profile: a portion of the structure of the body of the connecting rod is thus positioned in an area with a lower secondary flow velocity, and the impact on the aerodynamic performances of the connecting rod is thereby reduced;   the connecting rod comprises a shield which extends upstream from the body of the connecting rod with an apron: aerodynamic smoothing of the connecting rod is thereby obtained, notably during the initial phases for displacing a moveable cowl;   the second pivot point comprises a hub: replacing the ball joint currently used by such a hub, in the pivot point of the connecting rod foot attached to the fixed internal structure, the hub allows improvement in the stability of the connecting rod in all the maneuvering phases, one skilled in the art is aware of the hub width to be selected in order to adapt it to the morphology of the assembly;   at least one of said self-aligning means comprising any of the elements selected from a ball-jointed element and an elastic assembly such as the rings of the Paulstra™ type.       

     According to a second aspect, the present invention relates to a ducted-fan turbine engine nacelle comprising a downstream section, equipped with a thrust inversion device comprising a moveable cowl translationally mounted along a direction substantially parallel to a longitudinal axis of the nacelle capable of passing alternately from a closure position in which it ensures aerodynamic continuity of the nacelle and covers deflection means, to an open position in which it opens a passage in the nacelle and exposes the deflection means, said moveable cowl being also extended with at least one nozzle section mounted at one downstream end of said moveable cowl, and comprising at least one panel rotatably mounted around at least one pivot along an axis substantially perpendicular to a longitudinal axis of the nacelle, remarkable in that said panel is connected to a fixed fairing structure of the turbine engine through at least one bent connecting rod as described earlier, rotatably mounted around the first and second pivot points on the nozzle section panel and on the fixed structure respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other characteristics and advantages of the present invention will become apparent in the light of the description which follows with reference to the appended figures.  FIGS. 1 to 3   b  relate to connecting rods of the prior art, and  FIGS. 4 to 10  illustrate embodiments with connecting rods according to the present invention: 
         FIG. 1  illustrates a longitudinal sectional detailed view of the upstream section of an aircraft nacelle with a thrust inverter with a straight connecting rod from the state of the art connecting a moveable panel of the secondary nozzle to the fixed structure; 
         FIG. 2  illustrates a longitudinal sectional detailed view of the downstream section of an aircraft nacelle with a thrust inverter with the same straight connecting rod from the state of the art, but the pivot point of which of the connecting rod foot is further moved forwards upstream; 
         FIG. 3   a  illustrates a longitudinal sectional detailed view of the downstream section of an aircraft nacelle with a thrust inverter in an open position equipped with a bent connecting rod in one portion; 
         FIG. 3   b  illustrates a cross-sectional schematic view of a downstream section portion of an aircraft nacelle with a thrust inverter in the open position equipped with the bent connecting rod illustrated in  FIG. 3   a , with the stresses exerted on the pivot point of the moveable panel of the secondary nozzle; 
         FIG. 4  illustrates a profile view of a bent connecting rod in two portions according to the invention equipped with ball jointed elements; 
         FIG. 5  illustrates a bottom view of the foot of the bent connecting rod of  FIG. 4 ; 
         FIG. 6   a  illustrates a cross-sectional view of the foot of a connecting rod according to the invention on a section bearing a ball-jointed element; 
         FIG. 6   b  illustrates a cross-sectional view of the foot of a connecting rod according to the invention on a section which bears an elastic ring of the Paulstra™ type; 
         FIG. 7   a  illustrates a longitudinal sectional detailed view of the downstream section of an aircraft nacelle with a thrust inverter in the open position equipped with a bent connecting rod in two portions according to the invention; 
         FIG. 7   b  illustrates a cross-sectional schematic view of a downstream section portion of an aircraft nacelle with a thrust inverter in the open position equipped with the bent connecting rod illustrated in  FIG. 7   a , with the authorized angular deviations illustrated by arrows on the pivot point of the moveable panel of the nozzle; 
         FIG. 8  illustrates a longitudinal sectional detailed view of the downstream section of an aircraft nacelle with a thrust inverter in the closed position equipped with a bent connecting rod fitted into the fixed structure, and bearing a portion of the fairing of the turbine engine extended with an apron; 
         FIG. 9  illustrates the same view as  FIG. 8 , except that the thrust inverter is slightly open and the apron of the connecting rod foot is found in the secondary airflow; 
         FIG. 10  illustrates a longitudinal sectional profile view of the downstream section of an aircraft nacelle with a bent connecting rod in two portions according to the invention, the upper portion of which is designed so as to be connected to the moveable panel through a pivot point; and wherein according to a first option, the axis of this pivot point is placed at two thirds of the width of the profile of the connecting rod (connecting rod body in solid lines), or else, according to another option, the axis is placed in the middle of the width of the profile of the connecting rod (connecting rod body in dotted lines). 
     
    
    
     DETAILED DESCRIPTION 
     The terms of &lt;&lt;upstream&gt;&gt; and &lt;&lt;downstream&gt;&gt; in the present context are defined relatively to the direction of circulation of the cold airflow in the annular passage. The air intake of the turbine engine is located the most upstream from the cold airflow circulating in the annular passage, while the air outlet is located the most downstream from the cold airflow circulating in the annular passage. In the appended drawings which illustrate a nacelle section, the cold airflow circulates from left to right, thus the air intake is located towards the left and the air outlet towards the right of these figures. 
     A secondary nozzle  1  with a thrust inverter as illustrated in  FIG. 1 , has a moveable cowl  2  extended on its downstream portion with a moveable panel  3  which pivots on an axis substantially perpendicular to the longitudinal axis of the nacelle, substantially inscribed in the plane of  FIG. 1 . A straight connecting rod  7  is mounted on the moveable panel  3  through a first pivot point  5  on the one hand and to an internal fixed structure  9  through a second pivot point  11  on the other hand. The pivot point  11  of the connecting rod foot  7  should be positioned very downstream, preferably downstream from a convex fairing portion  13 . In order to allow the moveable cowl  2  to advance sufficiently so as to expose deflection means  15  (grids) by causing inclination of the moveable panel  3  so that it is found at the end of travel as illustrated in dotted lines on the right of  FIG. 1 . 
     In order not to penalize the performances of the engine by notably perturbing the aerodynamics of the annular passage  17 , the pivot point  11  of the connecting rod foot  7  should be shifted as far as upstream as possible, ideally upstream from the convex fairing portion  13  (see  FIG. 2 ). However, such a configuration does not allow the moveable cowl  2  to sufficiently uncover the deflection means  15  and the panel  3  does not follow the sought path. 
     In order to manage the displacement of the cowl  2  and of the panel  3 , while having an optimum position of the connecting rod relatively to the secondary flow, a bent connecting rod  19  is applied, the pivot point  21  of which on the fixed structure  9  is downstream from the body  23  of the connecting rod, when the moveable panel  3  is in the horizontal position. In order to stabilize the connecting rod, notably in the thrust inversion phase when the moveable panel  3  is inclined in a substantially transverse position relatively to the flow as illustrated in  FIG. 3   a , a sufficiently wide hub  25  fitted into the fixed structure  9  is used for stabilizing the connecting rod  19  during all the maneuvering phases. The pivot point  29  of the body  23  of the connecting rod is aligned with difficulty with the attachment point provided on the panel  3  (see  FIG. 3   b ), because of the imposed constraints as regards manufacturing and positioning tolerance, in the case of a bent connecting rod  19  in a portion as illustrated in  FIG. 3   a.    
     The present invention provides a connecting rod in two portions connected together by suitably selected attachment means so as to give certain flexibility to the assembly, with which it is possible to facilitate alignment of the different pivot points of the connecting rod, in particular during all the phases for displacing moveable parts. Such a connecting rod is illustrated in  FIGS. 4 to 7   b.    
     A bent connecting rod in two portions  31  may ideally include a first connecting rod member or body  33 , intended to be mounted to a moveable panel  3  of a secondary nozzle through the first pivot point or pivot point of the connecting rod body  35 , into which is embedded a second connecting rod member or foot  37 , intended to be mounted to the fixed structure  9  (see  FIG. 4 ) through the second pivot point or connecting rod foot pivot point  38 . Both members,  33 ,  37  are connected together by the self-aligning means  39   a  and  39   b , so that the foot  37  and the body  33  are attached to each other while retaining a certain freedom of displacement relatively to each other. The self-aligning means  39   a  and  39   b  are positioned between the connecting rod foot pivot point  38  and the bend  40 . The distance between the self-aligning means  39   a  and  39   b  is selected so as to be as large as possible in order to provide a maximum lever arm and reduce the torsion forces in the connecting rod in two portions  31 . 
     According to a particular embodiment, the self-aligning means  39   a  and  39   b  are ball-jointed elements  41   a  and  41   b , as this is illustrated on the foot of the bent connecting rod  31  as seen from below in  FIG. 5 . 
     The ball-jointed elements  41   a  and  41   b  of the embodiment illustrated in  FIG. 6   a , may be in certain cases advantageously replaced with elastic assemblies such as the rings of the Paulstra™ type  43   a  and  43   b , as illustrated in  FIG. 6   b . Such rings  43   a  and  43   b  do not require any particular maintenance. Indeed, it is not necessary to lubricate them, considering that they essentially comprise a ferruling of different rubber layers and of metal elements. 
       FIG. 7   b  illustrates the authorized angular deviation on the connecting rod body pivot point  35  by means of this type of bent connecting rod in two portions  31  equipped with self-aligning means  39   a  and  39   b , notably when the moveable panel  3  is completely inclined as illustrated in  FIG. 7   a . The axis A 1  and A 2  respectively correspond to the end positionings of the edge  34 , illustrated on the right of  FIG. 7   b  of the connecting rod body  33 , allowed by the displacement exerted by the self-aligning means  39   a  and  39   b.    
     Aerodynamic smoothing may be achieved in order to improve the fitting into the fixed structure  9  of the embedded portion of the connecting rod in two portions  31 , for example, on a portion  45  of the body of the connecting rod  33 , into which is embedded the connecting rod foot  37  (see  FIG. 8 ). A shield  47  may be provided in continuity with the fairing of the fixed structure  9 , and provided with an apron  48  in its most upstream portion of the secondary flow. Such an apron  48  provides a ramp to the flow which minimizes the aerodynamic perturbation during the swinging back of the connecting rod  31  towards the rear, as this is seen in  FIG. 9 . 
     In order to further improve the aerodynamic properties of the connecting rod in two portions  31  integrated in the annular passage  17 , the body  33  of the connecting rod is profiled so that the axis of the connecting rod body pivot point  35  crosses the profile of the body of the connecting rod in its middle.  FIG. 10  shows, in solid lines, a conventional arrangement with an axis which crosses the profile at one third of its width upstream, which is appropriate in the case of straight connecting rods in order to avoid alignment of the body of the connecting rod with the centre distance of the pivot points  35  and  38 . In this same  FIG. 10 , the profile of a connecting rod  31  according to the invention is illustrated in dotted lines, with the axis in the middle of the profile. With this arrangement, it is possible without changing kinematics, to bring back a portion of the structure of the connecting rod body  33  into an area with a lower velocity of the secondary flow in order to reduce the impact on the aerodynamic performances. 
     Of course, the present invention is by no means limited to the described and illustrated embodiments, provided as simple examples; and notably concerning the morphology of the embedment of both portions of the bent connecting rod  31 , of course it is possible to invert the structure of the interface with a self-aligning property of both members  33  and  37 , by making the yoke on the connecting rod foot  37  and transporting the self-aligning means onto the connecting rod body  33 .