Abstract:
The invention relates to a jet engine nacelle intended to equip an aircraft, formed from at least first and second half-shells and equipped with at least one locking system designed to lock one of the half-shells with respect to the other, the locking system being actuable between a locked state and an unlocked state by means of an actuating device ( 14 ). The actuating device ( 14 ) comprises a fixed body ( 29 ) in which an actuating rod ( 16 ) is translatably and rotatably mounted with respect to its longitudinal axis, the rod ( 16 ) having a first end equipped with a handle ( 17 ) and a second end connected to the locking system, the fixed body ( 29 ) having a track ( 30 ) cooperating with a follower element ( 24 ) projecting from the rod ( 16 ), the track ( 30 ) having a central portion ( 31 ) extending parallel to the axis (A) of the rod ( 16 ), on either side of which are respectively formed first and second end portions ( 32, 33 ) extending substantially perpendicularly to the axis of the rod ( 16 ).

Description:
TECHNICAL FIELD 
       [0001]    The disclosure relates to a nacelle for a turbojet engine intended to equip an aircraft. 
       BACKGROUND 
       [0002]    An aircraft is propelled by a number of turbojet engines each housed in a nacelle that also houses a collection of ancillary actuating devices associated with the operation thereof and performing various functions when the turbojet engine is operating or stationary. These ancillary actuating devices notably comprise a mechanical system for the actuation of thrust reversers. 
         [0003]    A nacelle generally has a tubular structure comprising an air intake forward of the turbojet engine, a middle section intended to surround a fan of the turbojet engine, a rear section that may house thrust reversal means and intended to surround the combustion chamber of the turbojet engine, and generally ends in a jet pipe, the outlet of which is situated downstream of the turbojet engine. 
         [0004]    Modern nacelles are often intended to house a bypass turbojet engine capable, via the blades of the rotating fan, of generating a flow of hot air (also known as the primary flow) from the turbojet engine combustion chamber. 
         [0005]    A nacelle generally has an outer structure, known as the Outer Fixed Structure (OFS), which, together with a concentric inner structure, known as the Inner Fixed Structure (IFS), defines an annular duct for flow, also known as a flow path, intended to channel a flow of cold air, known as the secondary flow, which passes around the outside of the turbojet engine. The primary and secondary flows are ejected from the turbojet engine via the rear of the nacelle. 
         [0006]    Each airplane propulsion unit is thus formed of a nacelle and of a turbojet engine, and is suspended from a fixed structure of the airplane, for example under a wing or on the fuselage, via a pylon or a strut attached to the turbojet engine or to the nacelle. 
         [0007]    The rear section of the outer structure of the nacelle is usually formed of a first and of a second half-shell of substantially semicylindrical shape, one on each side of a longitudinal vertical plane of symmetry of the nacelle, and movably mounted such that they can be deployed between a working position and a maintenance position with a view to providing access to the turbojet engine. The two half-shells are generally pivot-mounted about a longitudinal axis that forms a hinge in the top part (in the 12 o&#39;clock position) of the reverser. The half-shells are kept in the closed position by means of locking devices positioned at least along a meeting line situated in the bottom part (in the 6 o&#39;clock position). 
         [0008]    Conventionally, the nacelle is equipped with at least one locking system designed to lock one of the half-shells relative to the other, it being possible for the locking system to be actuated between a locked state and an unlocked state using an actuating device. 
         [0009]    The actuating device is generally in the form of a handle connected to a first end of a control rod mounted such that it can be moved translationally relative to the corresponding half-shell, the second end of the rod being connected to the actuating system. 
         [0010]    The translational movement of the handle by an operator unlocks or locks the locking system. 
         [0011]    A nacelle such as this has the disadvantages listed hereinbelow. 
         [0012]    In order to ensure that the locking system is correctly locked or correctly unlocked, the handle has to be moved over the full length of its travel. 
         [0013]    There is therefore a risk that an operator will move the handle translationally over just part of the handle travel, with the result that the locking system will not be correctly actuated. 
         [0014]    This may have repercussions during flight, when the locking system is not correctly locked. Furthermore, if the locking system is incompletely unlocked, there is a risk that the nacelle will become damaged during maintenance operations when the two half-shells are parted from one another. 
         [0015]    Another known actuating device comprises a rod that can move only in terms of rotation. This type of actuating device generally entails a preloading on the part of the operator, in order to actuate the locking system. When such a device is applied to a locking system that does not require preloading, the operator may consider the nacelle to have a locking fault and that additional checks need to be performed as a result. 
       BRIEF SUMMARY 
       [0016]    This disclosure addresses these disadvantages by proposing a nacelle that allows more reliable actuation of the locking system. 
         [0017]    To this end, the disclosure relates to a turbojet engine nacelle of the aforementioned kind, wherein the actuating device comprises a fixed body in which an actuating rod is mounted such that it can be moved translationally and rotationally with respect to its longitudinal axis, the rod having a first end equipped with a handle and a second end connected to the locking system, the fixed body comprising a track collaborating with a follower element that projects from the rod, the track having a middle part running parallel to the axis of the rod, on each side of which there are respectively formed a first and a second end part running substantially perpendicular to the axis of the rod. 
         [0018]    Thus, the locking system is actuated by performing the following succession of steps. First of all, the operator pivots the handle through a determined angle then pulls on the handle. Finally, he once again pivots the handle through a determined angle. The translational movement of the handle and therefore of the actuating rod actuates the locking system in the conventional way, the pivoting of the handle at the start and end of the rod travel ensuring that the rod has covered the full length of its travel. Furthermore, when a pivoting movement is performed at the start or at the end of the rod travel, that is to say when the follower element is collaborating with one of the end parts of the track which are positioned perpendicular to the axis of the rod, this rod is held in position. 
         [0019]    Hence, for example, there is no risk that the rod will shift under the effect of gravity. 
         [0020]    In an exemplary embodiment, the actuating device comprises means of immobilizing the rod, it being possible for these to be actuated alternately between a locked position in which the rod is prevented from moving and an unlocked position in which the rod can be rotated. 
         [0021]    In this way, when the follower finger is correctly positioned in one of the end parts of the track, an operator has first of all to actuate the immobilizing means in order to be able to cause the handle to pivot and then to move in a translational manner. This further improves the safety of the nacelle. 
         [0022]    Advantageously, the immobilizing means comprise a first sleeve slidably mounted on the rod between a locked position and an unlocked position, a second sleeve being mounted on the first sleeve and being fixed relative to the rod, the second sleeve comprising at least one opening in which at least one coupling element is mounted such that it can move, it being possible for the coupling element to be moved alternately between a position in which it couples the second sleeve and the body when the first sleeve is in the locked position, and a position in which it uncouples the second sleeve and the body when the first sleeve is in the unlocked position. 
         [0023]    Thus, in order to unlock the rod by turning, the operator has first of all to move the first sleeve into the unlocked position so that the coupling element is no longer rotationally coupling the second sleeve and the fixed body. If it fails to do this, if the first sleeve is in the locked position, the second sleeve, which is fixed relative to the rod, rotates as one with the fixed body. Thus, the rod cannot be pivoted and, as a result, the locking system cannot be actuated. 
         [0024]    In an exemplary embodiment, the coupling element is held in the opening of the second sleeve and is designed to collaborate with at least one complementary housing formed in the body in such a way as to couple the second sleeve and the body in terms of rotation, the first sleeve comprising an indentation positioned facing the coupling element when the first sleeve is in the unlocked position, and distanced from the coupling element when the first sleeve is in the locked position, the coupling element being housed, at least partially, in the indentation when the first sleeve moves into the unlocked position so as to break free from the housing formed in the body, the coupling element being freed from the indentation as the first sleeve moves into the locked position so as to engage in the housing formed in the body. 
         [0025]    Advantageously, the coupling element is a ball. 
         [0026]    In an exemplary embodiment, the first sleeve comprises an additional handle at that one of its ends that faces toward the handle with which the rod is equipped. 
         [0027]    In an exemplary embodiment, the actuating device comprises return means designed to move the first sleeve into the locked position. 
         [0028]    This feature is further aimed at improving the safety of the nacelle. 
         [0029]    Advantageously, the body comprises a first and a second housing that complement one another and are designed to collaborate with the ball when the rod is respectively in a first and in a second position, in which positions the follower element collaborates respectively with the first and second parts of the track which run substantially perpendicular to the axis of the rod. 
         [0030]    In this way, the rod can be immobilized in terms of rotation at the start and end of its travel, that is to say when the locking device is completely locked or unlocked. 
         [0031]    In an exemplary embodiment, the body comprises an outer part and an inner part which are fixedly joined together, the inner part being mounted on the second sleeve. 
         [0032]    This feature makes the body easier to produce. Specifically, production of the body has to take account of the manufacturing tolerances which are commonplace in the field of aeronautical engineering. 
         [0033]    Separating the body into two parts allows these requirements to be met while at the same time making the body simple to produce. Indeed, it then becomes possible to produce an outer part, which does not have a mechanical guiding function and does not have any function of holding the coupling element, with wide manufacturing tolerances, only the inner part intended to guide the rod being produced with tight tolerances and from a material which may differ. 
         [0034]    In an exemplary embodiment, the first sleeve is equipped with an indicator ring designed to be visible to an operator when the first sleeve is in the unlocked position and designed not to be visible when the first sleeve is in the locked position. 
         [0035]    The disclosure further relates to an aircraft equipped with a nacelle in an exemplary embodiment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    In any event, the disclosure will be clearly understood from the following description, with reference to the attached schematic drawing which, by way of example, depicts one embodiment of this nacelle. 
           [0037]      FIG. 1  is a schematic view of a nacelle in longitudinal section; 
           [0038]      FIG. 2  is an exploded perspective view of the rear section of the nacelle; 
           [0039]      FIG. 3  is a front view of part of the actuating device; 
           [0040]      FIG. 4  is a view corresponding to  FIG. 3 , in which the second sleeve is also depicted; 
           [0041]      FIG. 5  is a view corresponding to  FIG. 4 , in which the inner part of the body is also depicted; 
           [0042]      FIG. 6  is a view corresponding to  FIG. 5 , in which the first sleeve has been moved into the unlocked position; 
           [0043]      FIG. 7  is a front view of the outer part of the body; 
           [0044]      FIG. 8  is a view corresponding to  FIG. 5 , in which the rod has been moved; and 
           [0045]      FIG. 9  depicts the successive steps in the kinematics of the actuating device. 
       
    
    
     DETAILED DESCRIPTION 
       [0046]      FIG. 1  depicts a nacelle in an exemplary embodiment, intended to equip an aircraft. This nacelle has a tubular structure comprising an air intake  1  forward of the turbojet engine, a middle section  2  intended to surround a fan of the turbojet engine, a rear section  3  that may house thrust reversal means and which is intended to surround the combustion chamber of the turbojet engine, and ends in a jet pipe  4 , the outlet of which is situated downstream of the turbojet engine. 
         [0047]    The nacelle is intended to house a bypass turbojet engine capable, via the blades of the rotating fan, of generating a flow of hot air (also known as the primary flow) from the turbojet engine combustion chamber. 
         [0048]    The nacelle has an outer structure  5 , known as the Outer Fixed Structure (OFS), which, together with a concentric inner structure  6 , known as the Inner Fixed Structure (IFS), defines an annular duct  7  for flow, also known as a flow path, intended to channel a flow of cold air, known as the secondary flow, which passes around the outside of the turbojet engine. The primary and secondary flows are ejected from the turbojet engine via the rear of the nacelle. 
         [0049]    As is more particularly apparent in  FIG. 2 , the outer structure  5  comprises an inner cowl  8  and an outer cowl  9 . 
         [0050]    Each aircraft propulsion unit is thus formed of a nacelle and of a turbojet engine, and is suspended from a fixed structure of the aircraft, for example under a wing or on the fuselage, via a pylon or a strut  10  attached to the turbojet engine or to the nacelle. 
         [0051]    As may be seen in  FIG. 2 , the rear section  5  of the outer structure of the nacelle is formed of a first and of a second half-shell  11 ,  12  of substantially semicylindrical shape, one on each side of a longitudinal vertical plane of symmetry of the nacelle, and mounted such that they can move relative to the strut in such a way that they can be deployed between a working position and a maintenance position with a view to providing access to the turbojet engine. The two half-shells  11 ,  12  are each pivot-mounted about an axis A that forms a hinge in the top part (in the 12 o&#39;clock position) of the reverser. The half-shells are kept in the closed position by means of locking devices  13  positioned along a meeting line situated in the bottom part (in the 6 o&#39;clock position) and in the bottom part (in the 12 o&#39;clock position). The locking devices are actuated using a locking device. 
         [0052]    Disclosed is a particular type of locking device, the position of which is illustrated in  FIG. 2  using the reference  14 , the purpose of which is to actuate a locking system  15  located remotely with respect to the outer cowl of the nacelle, and of which the handle in the locked position does not protrude beyond the outer surface of the nacelle. 
         [0053]    The structure of the locking device according to an exemplary embodiment will now be described with reference to  FIGS. 3 to 8 . 
         [0054]    Part of the locking device  14  is depicted in  FIG. 3 . 
         [0055]    This device comprises an actuating rod  16  that has a first end equipped with a handle  17  of rectangular overall shape, and a second end  18  connected to the locking system  15 , as known per se by those skilled in the art. 
         [0056]    A first sleeve  19  is slidably mounted on the rod  16  between a locked position depicted particularly in  FIG. 3  and an unlocked position depicted in  FIG. 6 . 
         [0057]    The first sleeve  19  has a first end equipped with an additional handle  20  in the overall shape of a T. The first end of the first sleeve  19  passes through the handle  17  at an opening therein, the additional handle  20  being positioned in the rectangle delimited by the handle  17 . 
         [0058]    The position of the additional handle  20  and its shape allow an operator ergonomically to take hold of both the handle  17  and the additional handle  20 . 
         [0059]    A helical return spring  21  is positioned around the rod  16  and rests firstly against the first end of the first sleeve  19  and secondly against the handle  17  so that it forces the first sleeve  19  to move into the locked position. 
         [0060]    The first sleeve  19  also comprises, near the first end, a red indicator ring  22 , the purpose of which is explained hereinbelow. 
         [0061]    The second end of the first sleeve  19  comprises an indentation or a ramp  23  running longitudinally and inclined radially toward the axis A of the rod in the direction of the second end of the sleeve. 
         [0062]    The rod  16  is equipped with a follower finger  24  projecting outward. 
         [0063]    As has been depicted in  FIG. 4 , the actuating device  14  comprises a second sleeve  25  mounted on the first sleeve  19  and comprising an opening  26  through which the follower finger  24  passes in order fixedly to connect the second sleeve  25  to the rod  16 . 
         [0064]    The second sleeve  25  has a first end facing toward the handle  17  and set back therefrom. The second sleeve  25  is positioned in such a way that its first end covers the indicator ring  22  when the first sleeve  19  is in the locked position. The second sleeve  25  has a second end, set back from which there is an opening  27  that forms a housing for a ball  28 . The ball  28  is mounted such that it can move in the opening  27  between a locked position and an unlocked position, as better detailed hereinbelow. 
         [0065]    The opening  27  is positioned along the axis of the indentation  23  so that, when the first sleeve  19  is in the unlocked position, the ball  28  is positioned facing the indentation  23  so that it can become, at least partially, inserted therein and so that, when the first sleeve  19  is in the locked position, the ball  28  is distanced from the indentation  23  or presses against that part of the indentation  23  that is least indented with respect to the outer surface of the first sleeve  19 , it being recalled that the indentation  23  is inclined toward the second end of the aforementioned sleeve  19 . 
         [0066]    The diameter of the ball  28  is adjusted so that, when the first sleeve  19  is moved into the locked position, the ball  28  is moved into the locked position in which it projects from the second sleeve  25 . Further, when the first sleeve  19  is moved into the unlocked position, the ball  28  is also moved into the unlocked position in which it is housed in the opening  27  and/or in the indentation  23 . In this position, the ball  28  therefore no longer projects from the second sleeve  28 . 
         [0067]    An inner part  29  of a fixed body is mounted on the second sleeve  25 , the inner part  29  comprising a track having a middle part  31  formed by a longitudinal opening from the ends of which there run two openings  32 ,  33  which are positioned perpendicular to the middle part, thus forming first and second end parts  32 ,  33  of the track  30 . 
         [0068]    The track  30  thus has an overall C-shaped opening comprising three successive parts  31  to  33  inside which the follower finger  24  runs. 
         [0069]    The inner part  29  of the body further comprises a first and a second housing  34 ,  35  which are designed to collaborate with the ball  28  in respective first and second positions of the rod  16 , in which positions the follower element  24  collaborates respectively with the first and with the second end parts  32 ,  33  of the track  30 . 
         [0070]    The body further comprises a fixed outer part  36  mounted on the inner part  29  and having a track  37  similar to that of the inner part  29 , positioned facing the latter track, the follower finger  24  also running in the track  37  of the outer part  36 . The inner part  29  of the body is fixedly connected to the outer part  36  by a pin that has not been depicted. 
         [0071]    The way in which the actuating device  14  works will now be described in greater detail with the aid of  FIGS. 5 to 9 . 
         [0072]    More specifically,  FIG. 9  depicts a number of successive positions of the actuating device  14 . 
         [0073]    In a position, depicted in  FIG. 9   a , in which the locking system  15  is locked, the rod  16  and the handle are positioned in a top position, the follower finger  24  being positioned at the end of the track  30  at the first end part  32  thereof. 
         [0074]    In this position, the return spring  21  keeps the first sleeve  19  in the locked position, which means that the ball  28  is kept in the locked position in which it is inserted partially into the first housing  34  of the inner part  29  of the body. The ball  28  therefore allows the inner part  29  of the body to be coupled rotationally with the second sleeve  25 , itself fixed to the rod  16 . Because the inner part  29  is fixed, the rod  16  is so also and the operator cannot turn the handle  17 . As we saw earlier, in this position, the indicator ring  22  is covered by the second sleeve  25  and is therefore not visible to the operator. 
         [0075]    From this position, when the operator wishes to unlock the locking system  15 , he first of all pulls on the additional handle  20  so as to move the first sleeve  19  into the unlocked position. In this position depicted in  FIG. 9   b , the ball  28  may be moved into the unlocked position in which it is freed from the first housing  34  of the inner part  29  of the body so that this inner part  29  is no longer rotationally coupled to the second sleeve  25 . In this position, the indicator ring  22  of the first sleeve  25  is visible and the operator is able to turn the rod  16  so that the follower finger  24  moves across the first end part  32  of the tracks  30 ,  37  of the body, as can be seen in  FIG. 9   c.    
         [0076]    The operator then pulls on the handle  17  so that the rod  16  and the follower finger  24  are moved downward, as depicted in  FIG. 9   d , until they reach the bottom end of the middle part  31  of the tracks  30 ,  37 . In this position which has been depicted in  FIG. 9   e , the locking system  15  is therefore completely unlocked. 
         [0077]    The operator then turns the handle  17  so that the follower element  24  moves across the second end part  33  of the tracks  30 ,  37  of the body until it reaches the corresponding end of the track  30 . 
         [0078]    In this position which has been depicted in  FIG. 9   f , the ball  28  is positioned facing the second housing  35  of the inner part  29  of the body. Thus, when the operator releases the additional handle  20 , the return spring  21  forces the first sleeve  19  to move upward, that is to say into the locked position, so that the ball  28  is also moved into the locked position in which it is partially introduced into the second housing  35  of the inner part  29 , so as to couple this inner part and the second sleeve  25  rotationally. In this position, the rod  16  is once again prevented from turning. Further, in this position, the ring  22  is no longer visible to the operator, thus indicating to him that the handle has indeed been moved fully in such a way as to actuate the locking system. 
         [0079]    From this position, the locking system  15  is locked by performing the preceding steps in reverse sequence. 
         [0080]    It goes without saying, the disclosure is not restricted merely to the one embodiment of this turbojet engine nacelle which has been described hereinabove by way of example, but on the contrary encompasses all variants.