Abstract:
The invention relates to a guiding device ( 100 ) for part of a jet engine nacelle that can move in translation, comprising: (i) a rail ( 101 ) fixedly mounted on part of the nacelle, and (ii) a slide ( 102 ) which is connected to the mobile part and which can slide along the rail. The invention is characterised in that the guiding device is provided with a built-in retractable system for preventing the translational movement of the slide, for which purpose the device includes: (i) at least one blocking means ( 104 ) mounted such that it can move on the rail and occupy alternatively an engaged position in which it forms a translational abutment for the slide and a released position in which it is moved away from the slide and enables the relative translational movement of the slide beyond the locking system, and (ii) at least one means ( 130 ) for controlling the blocking means.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention relates to a guide device comprising a rail and a slide which are mounted such that they can move relative to one another and to a turbojet engine nacelle equipped with such a system. 
       BRIEF DISCUSSION OF RELATED ART 
       [0002]    An airplane is propelled by one or more propulsion units comprising a turbojet engine housed in a tubular nacelle. Each propulsion unit is attached to the airplane by a strut generally situated under a wing or at the fuselage. 
         [0003]    A nacelle generally has a structure comprising an air inlet upstream of the engine, a central section intended to surround a fan of the turbojet engine, and a downstream section intended to surround the combustion chamber of the turbojet engine and housing thrust reversal means. 
         [0004]    The air inlet comprises, on the one hand, an inlet lip designed to allow optimum funneling toward the turbojet engine of the air needed to be fed to the fan and to the internal compressors of the turbojet engine and, on the other hand, a downstream structure to which the lip is attached and which is intended to channel the air suitably toward the fan blades, said downstream structure comprising an external shell ring and an internal acoustic panel. The assembly is attached upstream to a fan casing that forms part of the central section of the nacelle. 
         [0005]    The central structure surrounds the fan and is generally broken down into an internal wall that forms said fan casing and an external wall in the form of removable cowls pivotably mounted about a longitudinal axis that forms a hinge at the upper part (in the 12-o&#39;clock position) of the nacelle so as to allow access to the inside of the nacelle. 
         [0006]    The way in which these various elements (moving cowls, casing, air inlet lip, external shell ring, acoustic panel) are joined together gives rise to numerous breaks in aerodynamic continuity owing to the presence of offsets and gaps between these elements which are inherent to the fact that they are joined together. What is more, the moving cowls are mounted on hinges, which also give rise to aerodynamic disturbances. 
         [0007]    A solution for improving the aerodynamic continuity of the external surface of a nacelle is covered in the as-yet unpublished French patent applications No. 06/08599 and No. 07/01256. 
         [0008]    This solution consists in incorporating the air inlet lip into the external shell ring, including therein all or part of the cowl that surrounds the fan casing, so as to form a one-piece structure. 
         [0009]    Advantageously, this structure is fitted with translational guidance means of the rail/slide type allowing said cowl easily to be opened and providing access to the inside of the nacelle. 
         [0010]    Advantageously too, these guide means may be dismantled so as to allow said structure to be removed and possibly replaced. 
         [0011]    It will therefore be appreciated that the rail/guide systems need to be fitted with end-of-translation retaining means (end-of-travel end stops) which nonetheless allow a disengaged position that will allow the rail/slide system to be dismantled. 
         [0012]    These end-of-travel end stops for the end of travel of the moving external cowl need to be able to be retracted so that the moving external structure can be replaced, while at the same time returning to an operational state without fail when an external cowl is refitted. 
         [0013]    Known ways of achieving this include various end-of-travel spoiler systems for a rail with rolling runners that entail maneuvering the cowl in a special way in order to allow it to be disengaged, or alternatively end stop means. 
         [0014]    Nonetheless, these systems do not generally meet the need for ease of access and ease of maneuvering of the end stop means and there is a need for an improved locking system. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    The invention alleviates the abovementioned disadvantages and proposes an improved retaining system and for that reason the present invention comprises a guide device for a translationally moving part of a turbojet engine nacelle and comprising, on the one hand, a rail mounted fixedly on a part of the nacelle and, on the other hand, and a slide attached to the moving part and able to slide along the rail, where said guide device is equipped with an in-built retractable system for stopping the translational movement of the slide, and comprising, in order to do this, on the one hand at least one immobilizing means mounted such that it can move on the rail and able to move alternately from an engaged position in which it constitutes a translational end stop for the slide and a disengaged position in which it is away from the slide and allows a relative translational movement of the latter beyond said locking system and, on the other hand, at least one control means for controlling the immobilizing means. 
         [0016]    In general, a rail means the male part of the rail/slide system and the term slide denotes the female part. 
         [0017]    Thus, by equipping the rail with retractable end stops there is obtained a locking system that is simple to activate, that meets the demanded safety requirements while at the same time allowing the rail and the slide to be dismantled from one another when necessary in order to remove moving parts. 
         [0018]    It will also be noted that, in the application in question, it is advantageous to keep the rail fixed, which allows better guidance and better fixing. Further, the fact that the rail is fixed means that the locking and control means can be arranged in a special way. 
         [0019]    Advantageously, the immobilizing means is fixed at a first end of the rail. Thus, the immobilizing means is able to form an end-of-travel end stop giving the slide the greatest possible margin for maneuver. 
         [0020]    Advantageously too, the control means is mounted at a second end of the rail. 
         [0021]    As a preference, the control means is able to be returned from an unlocked position to a locked position during the return of the slide, thereby causing the immobilizing means to return to its engaged position. In this way, reengaging the slide with the rail when the removed panel is returned to its position causes the immobilizing means to be returned automatically to their engaged position. This results in a significant additional safety feature by making it possible to prevent any omission to reactivate the locking system on the part of the operator. 
         [0022]    Advantageously, the control means has two stable positions and is mounted against the action of an elastic return means which, when the control means is between two stable positions, tends to return it toward one or other of the positions. 
         [0023]    According to a preferred embodiment of the invention, the immobilizing means is in the form of a heel piece mounted such that it can pivot on the rail. 
         [0024]    In addition, the guide device comprises a connecting means connecting the control means to the immobilizing means. 
         [0025]    As a preference, the rail is hollow and houses all or part of the connecting means. 
         [0026]    Advantageously, the immobilizing means is mounted against the action of at least one elastic return means that tends to return it toward its engaged or disengaged position. 
         [0027]    Advantageously too, the connecting means is a rod mounted with the capacity for translational movement and able to be moved, under the effect of the control means, alternately between a first position in which it keeps the immobilizing means in its position in which the elastic return means is stressed, and a second position in which the elastic return means is at rest. 
         [0028]    The present invention also relates to a nacelle for a turbojet engine comprising an air inlet structure able to channel an air flow toward a fan of the turbojet engine and a central structure intended to surround said fan and to which the air inlet structure is attached, the air inlet structure and possibly the central structure having at least one external panel comprising a one-piece wall, characterized in that the external panel is mounted with the capacity for translational movement with the aid of a guide system according to the invention. 
         [0029]    Advantageously, the rail of the guide device is secured to a fixed part of the nacelle while the slide is connected to the moving external panel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The way in which the invention is implemented will be better understood from the detailed description which is set out hereinbelow with reference to the attached drawing, in which: 
           [0031]      FIGS. 1 and 2  are sectioned partial schematic depictions of an air inlet structure of a turbojet engine nacelle equipped with a guide system according to the invention. 
           [0032]      FIG. 3  is a schematic depiction of the guide system according to the invention, in the position in which the external cowl is locked and closed. 
           [0033]      FIG. 4  is a schematic depiction of the guide system according to the invention, in the position in which the external cowl is locked and open. 
           [0034]      FIG. 5  is a schematic depiction of the guide system according to the invention, in the position in which the external cowl is unlocked and open. 
           [0035]      FIG. 6  is a schematic depiction of the guide system according to  FIG. 5  and in which the external cowl is in the process of being removed. 
           [0036]      FIG. 7  is a schematic depiction of the guide system according to  FIG. 5  and in which the external cowl is in the process of being refitted, and 
           [0037]      FIG. 8  is a schematic depiction of the guide system at the end of the refitting of the external cowl with the locking means returned to the engaged position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    A nacelle (not depicted) constitutes a tubular housing for a turbojet engine and channels the air flows that it generates defining the internal and external aerodynamic lines necessary to obtain optimal performance. It also houses various components necessary for the operation of the turbojet engine, together with ancillary systems such as a thrust reverser. 
         [0039]    The nacelle is intended to be attached to a fixed structure of an airplane, such as a wing, via a pylon. 
         [0040]    More specifically, a nacelle has a structure comprising a front section that forms an air inlet  4 , a central section  5  intended to surround a fan of the turbojet engine, and a rear section (not visible) surrounding the engine of the turbojet engine and generally housing a thrust reversal system. 
         [0041]    The air inlet  4  splits into two zones, namely, on the one hand, an inlet lip  4   a  designed optimally to funnel toward the turbojet engine the air needed to be fed to the fan and to the internal compressors of the turbojet engine and, on the other hand, a downstream structure  4   b  comprising an external panel  40  and an internal panel  41  and to which the lip  4   a  is attached and which is intended to channel the air suitably toward the fan blades. 
         [0042]    The central section also breaks down into an external wall and an internal wall comprising a casing of the fan. 
         [0043]    A nacelle that has an air inlet structure as depicted in  FIGS. 1 and 2  has a lip  4   a  incorporated into the external panel  40 , it being possible for said external panel also to incorporate, at least in part, the external wall of the central structure  5 . The external wall  40  and the air inlet lip  4   a  therefore form a single dismantlable component extending over the entire upstream part of the nacelle. The internal panel  41  for its part is attached upstream of the fan casing via fixing flanges. 
         [0044]    The external panel  40  may be modular and comprise a plurality of longitudinal external panels each defining a portion of the external wall of the nacelle. In such a case, the external structure of the nacelle will have meeting lines running longitudinally with respect to the nacelle, and these will have only a negligible impact on the aerodynamic continuity of the air inlet structure  4 , unlike a nacelle according to the prior art that has a peripheral meeting line where the external panel  40  meets the lip  4   a  and where the external panel  40  meets the external panel of the central section  5 , said meeting line running transversely with respect to the direction of the air flow. 
         [0045]    As shown in  FIGS. 1 and 2 , the external panel is mounted with the capacity for translational movement along a substantially longitudinal axis of the nacelle to make it easier to remove and/or to replace. 
         [0046]    This translational movement is performed by virtue of the installation of guide means  100  according to the invention, comprising a rail  101  collaborating with a slide  102 . 
         [0047]    The present invention will be illustrated by a guide system  100  comprising a rail  101  fixedly mounted on the internal wall  41  and a slide  102  fixedly connected to the external panel  40 . Quite clearly, the present application is not restricted to such a configuration and it is entirely possible for the invention to be extended to cover a rail fixed to the moving external panel and collaborating with a fixed slide of the nacelle; or alternatively to use a rail with rollers, for example. 
         [0048]    As explained, a nacelle as described hereinabove allows simple opening of the entire upstream section of the nacelle but also at the same time allows said external panel  40  to be removed. 
         [0049]    As a result, the guide system  100  needs to allow the slide to be halted at the end of its travel when the external panel  40  is simply being opened, but needs also to be able to allow an over-travel of the slide  102  so that it can be disengaged from the rail  101  and the external panel can be removed. 
         [0050]    The present invention aims to provide such a guide system  100  which is depicted during the course of various steps in  FIGS. 3 to 8 . 
         [0051]    As previously stipulated, a guide system  100  comprises a rail  101  on which there is mounted a slide  102  capable of translational movement along said rail  101 . 
         [0052]    The rail  101  is hollow and incorporates a retractable translational immobilization system. 
         [0053]    For this, the rail  101  has a first end  103  in which two heel pieces  104  are mounted facing one another. 
         [0054]    Each heel piece  104  has a first end  104   a  forming a pivot and via which it is mounted on an axis of rotation against the wall of the rail  101  and a second end  104   b  that projects from the first end  103  of the rail  101  forming a return  105  able to project laterally from the rail  101  when the heel piece  104  is pressed against the wall of the rail  101  (engaged position) but not protruding laterally beyond the rail  101  when the heel pieces are sufficiently far away from the wall of the rail  101  (disengaged position). 
         [0055]    The heel pieces  104  are connected to one another by a spring  106  that constitutes an elastic return means that tends to return them to their disengaged position. Alternatively, it is equally possible to imagine equipping each heel piece  104  with a spring mounted against the wall of the rail  101  and tending to push them away from said wall. 
         [0056]    Each heel piece  104  has, at its end  104   b , a beveled face  107  intended to collaborate with a corresponding frustoconical end  121  of a connecting rod  120  mounted with the capacity for translational movement inside the rail  101  and able to move alternately from a first position in which the frustoconical end acts as an end stop for the heel pieces  104  and keeps them in their engaged position against the action of the spring  106 , to a second position in which the frustoconical end  121  is away from the heel pieces  104  and allows them, under the effect of the spring  106 , to return toward their disengaged position. 
         [0057]    The rod  120  is made to move between its two positions by means of a trigger  130  positioned at a second end  108  of the rail  101 . 
         [0058]    The trigger  130  is mounted such that it can rotate between two stable positions and is connected to the rod  120  by a link  131 . 
         [0059]    The trigger  130  is also connected to an elastic return means  132  allowing it to be kept in each of the two stable positions and to be returned to one of its two positions when it is in an unstable intermediate position. 
         [0060]    The two stable positions of the trigger  130  are determined in such a way that, on the one hand, when actuated into its first stable position, the trigger  130 , via the link  132 , drives the rod  120  into its position of separation from the heel pieces  104  which then move into the disengaged position and, on the other hand, when actuated into its second stable position, the trigger  130  via the link  132  returns the rod  120  to its position of engagement with the heel pieces  104  which, as explained hereinabove, are then kept in their engaged position. 
         [0061]    It will also be noted that the trigger is equipped with an extension  133  arranged in such a way that it projects laterally from the rail  101  when the heel pieces  104  are in the disengaged position. 
         [0062]    The various steps in implementing the guide system  100  and its in-built locking system will now be explained with the aid of  FIGS. 3 to 8 . 
         [0063]      FIG. 3  illustrates the guide system  100  in its initial position when the external panel  40  is closed and the heel pieces  104  are in their engaged position. 
         [0064]    In this position, the slide  102  is retreated toward the second end  108  of the rail  101 . As for the in-built immobilizing system, the heel pieces  104  are kept in the engaged position, that is to say in the position in which they project laterally from the rail  101 , by the end  121  of the rod  120 . The trigger  130  is in the corresponding stable position. 
         [0065]      FIG. 4  illustrates the guide system  101  in the case of simple opening of the external panel  40  without its removal. In this configuration, the heel pieces  104  are still in the engaged position and the slide  102  has slid toward the first end  103  of the rail  101  until possibly it has come into abutment against the return  105  of the heel pieces  104 . 
         [0066]      FIGS. 5 to 8  illustrate the steps involved in completely removing and possibly replacing the external panel  40 . 
         [0067]    To do this, the trigger  130  is pivoted by hand or through an electric control into its second stable position. 
         [0068]    It will be noted that the locking means are located at one end of the rail while the control means are located at the second end. This is because such positioning is advantageous because it allows ease of access to the control means, the moving cowl  40  beginning to open from the side at which the control means are located. 
         [0069]    As this happens, the link  132  transmits this movement to the rod  120  which undergoes a slight translational movement until the frustoconical end  121  has moved away from the heel pieces  104  to allow them, under the effect of the spring  106 , to return to their disengaged position. 
         [0070]    Thus, the returns  105  of the heel pieces  104  no longer project laterally from the rail  101  and the slide  102  is free to continue its travel as illustrated in  FIG. 6  so that the rail  101  and the slide  102  can be disengaged, allowing the external panel  40  to be removed. 
         [0071]    As illustrated in  FIG. 7 , the external panel  40  or a new panel is refitted by performing the procedure in reverse. 
         [0072]    However, as is depicted in  FIG. 8 , the locking system is able automatically to return to the engaged position once the external panel  40  has been refitted. 
         [0073]    What happens is that when the external panel  40  is returned to the closed position, the slide  102  undergoes a translational movement along the rail  101  toward its second end  108  where the extension  133  of the trigger projects laterally from the wall of the rail  101 . 
         [0074]    As the external panel  40  is returned to the closed position, the slide butts against said extension  133  of the trigger and pushes it back, thus causing the trigger  130  to return to its first stable position and, as a result, causing the heel pieces  104  to reengage. 
         [0075]    The external panel  40  is manipulated in the conventional way using suitable tooling mounted on lifting points, advantageously situated near the center of gravity of the wall. Hence it is easy to perform a pivoting by hand in order to fit and remove said one-piece wall. Optionally, the lifting point may be situated inside a casing of a latch. 
         [0076]    Although the invention has been described in conjunction with specific exemplary embodiments, it is quite obvious that it is not in any way restricted thereto and that it comprises all technical equivalents of the means described and combinations thereof where these fall within the scope of the invention. 
         [0077]    In particular, it would be possible to provide retractable end stops of different shapes. It will also be noted that the present guide system is not limited to an air inlet external panel but could also be applied to the guidance of any moving part of a nacelle. 
         [0078]    It will finally be noted that the locking system according to the invention may be combined with an electric drive and control system, possibly associated with a sensor to detect that the external panel has been re-closed.