Abstract:
An aircraft nacelle with a system to provide spacing between two halves of a cowl. The cowls open and close by rotating about an axis in the upper regions of the cowls, and the cowls have indexing features in a region of the lower edges. The indexers are in sliding contact the spacing system, which is rigidly mounted to the nacelle. The spacing system comprises a housing for receiving the indexers and two levers with features for prescribing the movement of the cowls. The spacing system further comprises an actuator and a plurality returns to assist the movement of the cowls.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of and priority to French patent application No. 14 53048 filed on Apr. 7, 2014, the entire disclosure of which is incorporated by reference herein. 
     BACKGROUND 
     The present disclosure relates to an aircraft nacelle comprising two cowls and a spacing system which is intended to maintain the two cowls spaced apart, and an aircraft comprising at least one such nacelle. 
     An aircraft comprises at least one nacelle in which there is received an engine, for example, of the turbojet type, and which is suspended on a strut. The nacelle generally comprises two cowls (or fan cowls) which may be opened in order to allow the maintenance of the engine to occur. 
     Each cowl is articulated about an opening axis which is parallel with the longitudinal axis of the nacelle and which is arranged in the upper portion of the cowls, and the two cowls are arranged symmetrically at one side and the other of the strut. 
     Each cowl is thus movable between a closed position, in which the cowl is arranged in the extension of the outer surface of the nacelle so as to cover the casing of the fan, and an open position, in which an operator may access the engine. 
     The lower edges of the cowls, which are located in the lower portion of the nacelle, are substantially in abutment in the closed position and are maintained in that locked position by a plurality of locking systems which are distributed along the abutting lower edges of the cowls. 
     In order to prevent the unexpected closure of the cowls, it is known to provide a spacing system (called a “Hold Open Device” (HOD)) in the region of the lower edges of the cowls. That spacing system maintains the two cowls spaced apart and only an intentional action by a technician on the spacing system allows the two cowls to be moved together and placed in a closed position. 
     Current spacing systems are completely satisfactory when the cowls are sufficiently rigid. As a result of the composite materials which are used increasingly and because of the increase in the dimensions of the cowls, the cowls have a tendency to become more flexible and to become deformed more readily. 
     As a result of that flexibility, the lower edges of the cowls may be moved together without the technician acting on the spacing system. Therefore, there is a risk that the lower edges of the cowls may move together and the technician, seeing the two cowls in abutment, may consider the cowls to be locked. 
     SUMMARY 
     An object of the present disclosure is to provide an aircraft nacelle which comprises two cowls and a spacing system of the two cowls which does not have the disadvantages of the prior art and which particularly maintains the lower edges of the cowls spaced apart in an effective manner. 
     To that end, there is provided a nacelle comprising:
         two cowls, each having a lower edge and an indexer in the region of the lower edge, the two cowls being mounted so as to be movable in terms of rotation about an opening axis between a closed position, in which the lower edges are in contact, and an open position, in which the lower edges are spaced apart from each other,   a spacing system comprising:
           a base which is fixed to a fixed portion of the nacelle,   for each cowl, a lever which is independent of the lever which is associated with the other cowl and which has a housing in which the indexer is received when the corresponding cowl is in a closed position, and a stop against which the indexer is positioned when the corresponding cowl is in an open position, the lever being movable in terms of rotation on the base between an engagement position, in which the indexer is in the housing or against the stop, and a disengagement position, in which the lever is retracted in order to allow the movement of the indexer from the housing toward the stop, and vice versa, and   for each lever, a return which is intended to urge the lever into the engagement position.   
               

     Such a spacing system prevents the cowls from moving together if a technician does not intervene directly in the spacing system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the disclosure herein mentioned above and others will be appreciated more clearly from a reading of the following description of an embodiment, the description being given with reference to the appended drawings, in which: 
         FIG. 1  shows an aircraft according to the disclosure herein; and 
         FIGS. 2 to 7  show a spacing system according to the disclosure herein in different positions. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an aircraft  10  which comprises two nacelles  12   a - b  which are of substantially cylindrical form. Each nacelle  12   a - b  is fixed below a strut  14   a - b  of the aircraft  10  and comprises two cowls  16   a - b  which are mounted so as to be movable in terms of rotation at one side and the other of the strut  14   a - b  about an opening axis which is parallel with the longitudinal axis of the nacelle  12   a - b.    
     The lower edges of the cowls  16   a - b  move into contact when the cowls  16   a - b  are in a closed position and move away from each other when the cowls  16   a - b  are in an open position. 
     Each cowl  16   a - b  comprises, in the region of the lower edge thereof, an indexer  18  for providing an approach for indexing. 
       FIGS. 2 to 7  show a spacing system  100  in different operating positions. In  FIGS. 2 to 6 , only half of the spacing system has been illustrated, but it is symmetrical in relation to the axis of symmetry  20 . In the description of  FIGS. 1 to 6 , therefore, reference has only been made to the right portion of the nacelle  12   a , but the left portion is identical. 
     The spacing system  100  comprises a base  102  which is fixed to a fixed portion of the nacelle  12   a , for example, fixed to the rear wall of the air inlet of the nacelle. 
     For each cowl  16   a - b , the spacing system  100  comprises a lever  104  which has a housing  108 , in which the indexer  18  is received when the corresponding cowl  16   a - b  is in a closed position, and a stop  110 , against which the indexer  18  is positioned when the corresponding cowl  16   a - b  is in an open position in order to prevent it from being closed. 
     The lever  104  is provided to be movable in terms of rotation on the base  102  between an engagement position which corresponds to the fact that the indexer  18  is positioned in the housing  108  or against the stop  110 , and a disengagement position which involves retraction of the lever  104  in order to allow the movement of the indexer  18  from the housing  108  toward the stop  110 , and vice versa. 
     The rotation on the base  102  is carried out about a rotation axle  106  which is parallel with the opening axis. 
     The spacing system  100  also comprises for each lever  104  a return which urges the lever  104  into the engagement position and beyond in relation to the disengagement position. The return is, for example, a spring which is mounted on the rotation axle  106 . 
       FIG. 2  corresponds to the closed position of the cowls  16   a - b . The indexer  18  is in the housing  108  and the spacing system  100  is in the engagement position. 
       FIG. 5  corresponds to the open position of the cowls  16   a - b . The indexer  18  is against the stop  110  and the spacing system  100  is in the engagement position. 
       FIG. 4  corresponds to the disengagement position of the spacing system  100  where the indexer is free to move from the housing  108  to the stop  110  and vice versa. 
       FIG. 3  corresponds to an intermediate position between the engagement position and the disengagement position. 
       FIG. 6  corresponds to a completely open position of the cowls  16   a - b  where the indexer  18  is beyond the stop  110 . 
     The positioning of the indexer  18  in the housing  108  and the positioning of the lever  104  in the engagement position correspond to the closed position of the cowl  16   a - b.    
     The positioning of the indexer  18  against the stop  110  and the positioning of the lever  104  in the engagement position correspond to the open and spaced-apart position of the cowl  16   a - b.    
     The lever  104  of one of the cowls  16   a - b  is independent of the lever  104  of the other cowl  16   b - a.    
     The spacing system  100  also comprises one or more actuator  150  which is common to the two levers  104  and provided to be actuated by a technician and to authorize the movement of each lever  104  from the engagement position to the disengagement position, and thereby to authorize the movement of the indexer  18  from the stop  110  toward the housing  108  and thus the movement of the cowl  16   a - b  from the open position to the closed position thereof. 
     In the engagement position, when the indexer  18  is in abutment against the stop  110 , the lever  104  is provided to prevent the movement of the indexer  18  toward the housing  108  and therefore the movement of the associated cowl  16   a - b  from the open position to the closed position without being urged by the technician. 
     Operation of the spacing system  100  will now be described on the basis of the closed position of the cowls  16   a - b.    
     In  FIG. 2 , the lever  104  is urged (arrow  22 ) by the return into the engagement position and the cowls  16   a - b  are closed. 
     In  FIG. 3 , the cowls  16   a - b  open (arrow  30 ). The indexer  18  slides against a wall of the housing  108 , which wall is provided for this purpose, under the lever  104  and the lever  104  rises (arrow  32 ) by rotation in order to allow the indexer  18  to pass progressively. 
     In  FIG. 4 , the indexer  18  progressively leaves the housing  108  and continues to lift the lever  104 . 
     In  FIG. 5 , the indexer  18  has left the housing  108  and the return lowers the lever  104  (arrow  22 ). The indexer  18  is then positioned against the stop  110 , which prevents the indexer  18  from lifting the lever  104  in order to move back into the housing  108 . 
     If the cowl  16   a - b  attempts to close again (arrow  34 ,  FIG. 5 ) without any intervention by the technician, the indexer  18  applies to the stop  110  a pressure which brings about a rotation of the lever  104  in the direction of a lowering action (arrow  22 ) of the lever  104 , that is to say, a displacement beyond the engagement position in relation to the disengagement position. Such a lowering action prevents the movement of the indexer  18  under the lever  104  in order to reach the housing  108 . 
     Even when the cowl  16   a - b  is flexible, its non-authorized closure is thereby impossible. 
     Operation of the spacing system  100  will now be described on the basis of the open position of the cowls  16   a - b.    
     In  FIG. 5 , the indexer  18  is in abutment against the stop  110 . 
     The action of the technician on the actuator  150  brings about the movement of the lever  104  from the engagement position ( FIG. 5 ) to the disengagement position ( FIG. 4 ). 
     In  FIG. 4 , the indexer  18  moves freely from the position against the stop  110  to the position in the housing  108  ( FIG. 3 ). 
     After the actuator  150  has been released, the lever  104  moves back into an engagement position under the effect of the return and with the indexer  18  in the housing  104  ( FIG. 2 ). 
     In  FIG. 6 , the cowl  16   a  continues to open (arrow  30 ) and the lever  104  thus continues to be lowered (arrow  22 ) under the effect of the return. 
     In order to prevent any contact between the lever  104  and the lower edge of the cowl  16   a - b  during this continued opening action, that is to say, when the indexer  18  is beyond the stop  110  in relation to the housing  108 , the lever  104  has an extension  602  (visible in  FIG. 7 ), against which the indexer  18  slides during the movement thereof. The extension  602  is a plane in this instance. 
     The actuator  150  comprises a rod  152  which is movable in terms of translation (arrows  36  and  38 ) on the base  102  and a beam  154  which is mounted on the rod  152 . 
     One of the ends of the beam  154  forms with one of the levers  104  a rectilinear linear connection (cylinder/plane) having an axis parallel with the opening axis and the other end of the beam  154  forms with the other lever  104  a rectilinear linear connection (cylinder/plane) having an axis parallel with the opening axis. 
     To that end, each end has an oblong hole  158  and the lever  104  has a stud  112  which is arranged in the oblong hole  158 . 
     Operation of the actuator  150  is as follows. 
     When the lever  104  is moved, the rectilinear linear connection allows the movement of the stud  112 , and therefore of the lever  104 , in relation to the beam  154 . 
     From the closed position of the cowls  16   a - b , the movement of the lever  104  from the engagement position ( FIG. 2 ) toward the disengagement position ( FIG. 4 ) brings about the movement of the rod  152  in the direction  38 . The movement of the lever  104  from the disengagement position ( FIG. 4 ) toward the engagement position ( FIG. 2  or  FIG. 5 ) brings about the movement of the rod  152  in the direction  36 . 
     From the open position ( FIG. 5 ) of the cowls  16   a - b , the technician pushes the rod  152  in the direction  38  which tends to cause each lever  104  to move from the engagement position ( FIG. 5 ) to the disengagement position ( FIG. 4 ), lifting each lever  104 , and thereby to allow the movement of the indexer  18  from the position in abutment against the stop  110  toward the position in the housing  108 . 
     After the rod  152  is released, each return brings about the movement of each lever  104  toward the engagement position ( FIG. 2 ) and therefore the movement of the rod  152  in the direction  36 . 
       FIG. 7  shows the independence of the lever which is associated with one of the cowls  16   a  and the lever which is associated with the other cowl  16   b.    
     The beam  154  is mounted so as to be movable in terms of rotation on the rod  152  about a rotation axle  156  which is parallel with the opening axis. Thus, one of the cowls  16   a  may be in an open position while the other cowl  16   b  may be in a closed position, since each lever  104  may have, along the beam  154 , a position which is independent of that of the other lever  104 . 
     While at least one exemplary embodiment of the invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.