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You are an expert at summarizing long articles. Proceed to summarize the following text: 
TECHNICAL FIELD 
       [0001]    A locking device is used in particular in order to be fitted to a nacelle, itself designed to be fitted to an aircraft. 
       BACKGROUND 
       [0002]    A nacelle is a streamlining element making it possible to protect a jet engine of an aircraft. A nacelle usually comprises two elements articulated on the pylon of the aircraft so as to allow access to the engine housed inside the nacelle, particularly during maintenance operations. 
         [0003]    Conventionally, a nacelle comprises at least a first and a second locking device, comprising respectively a first and a second locking system, fitted with a first and a second control handle, designed to be actuated by an operator. 
         [0004]    The first locking system is designed to lock the nacelle in the junction zone placed in the bottom portion, that is to say at 6 o&#39;clock, while the second locking system is designed to achieve the locking in the junction zone placed in the top portion, that is to say at 12 o&#39;clock. 
         [0005]    The handles are both placed in the bottom portion of the nacelle, for reasons of accessibility. 
         [0006]    The use of such locking devices has the drawbacks explained below. 
         [0007]    When the nacelle is opened, the two elements are articulated about shafts situated in the top portion, the elements being subjected to the action of cylinders. 
         [0008]    The first locking system situated in the bottom portion is capable of preventing an accidental opening of the nacelle when the latter is locked. Specifically, the first locking system is situated at a distance from the articulation shafts of the two elements of the nacelle and the force exerted by the cylinders is not sufficient to cause damage to the first locking system or to the nacelle. 
         [0009]    Conversely, if only the second locking system situated in the top portion of the nacelle is locked, the latter is not capable of withstanding the force exerted by the cylinders, unless a particular and constraining design of the structure of the nacelle is provided. In this case, the second locking system, or even the articulated elements of the nacelle, can be greatly damaged. 
         [0010]    In addition, the operator is forced to actuate two handles in order to unlock or lock the aforementioned locking devices, which is awkward and easily gives rise to operating errors, the consequences of which are in particular explained above. 
         [0011]    The risk of such an operating error is all the greater if the operator does not see the second locking system placed in the top portion of the nacelle. The closure of the latter is therefore carried out “blind”. 
         [0012]    Finally, other drawbacks are the complexity, the weight and the space requirement of the two locking devices. 
       BRIEF SUMMARY 
       [0013]    The invention relates to a locking device comprising a first locking system fitted with a control handle, designed to be actuated by an operator, characterized in that it comprises a second locking system, connected to the first by linking means arranged to actuate the second locking system via the actuation of the first, the first locking system being actuated alternately between a locked state and an unlocked state by the displacement of the handle over the whole of a determined travel, the linking means comprising sequencing means arranged to actuate the second locking system, respectively between a locked state and an unlocked state of the latter, when the handle is moved over only a portion of the travel of the latter. 
         [0014]    In this manner, when the locking device is opened with the aid of the handle, the second locking system is unlocked or “opened” before the first. Therefore, when the first locking system is completely unlocked, the operator is certain that the second locking system is as well. 
         [0015]    Similarly, when the locking device is closed, the second locking system is locked or “closed” before the first. Therefore, when the first locking system is completely locked, the operator is certain that the second locking system is as well. 
         [0016]    Therefore, in an example of application to a nacelle, the first locking system is advantageously that placed at 6 o&#39;clock, the second being that placed at 12 o&#39;clock. 
         [0017]    The sequencing between the actuation of the two locking systems also makes it possible to compensate for the adjustment and regulation tolerances of the linking means. Specifically, if it was envisaged to simultaneously control the two locking systems with the aid of the handle, that would require precise regulation and adjustment of the linking means between the two locking systems, which is particularly difficult with movable elements that are a distance apart. This also becomes very constraining with elements subjected to high temperature differences because of the effects of expansion of the materials and of the large dimensions of the elements. If the two locking systems are not controlled in an exactly simultaneous manner, the aforementioned risk of damage still remains when the nacelle is accidentally opened. 
         [0018]    Finally, in the absence of sequencing, and in the event of poor regulation, the operator forces the whole line of control which has to be sized accordingly. 
         [0019]    The sequencing therefore makes it possible to dispense with a precise regulation of the linking means, making the device safer and less costly in manufacturing and maintenance terms. 
         [0020]    Advantageously, the sequencing means comprise a cam comprising a track interacting with a follower element moving along the latter, the track comprising an active portion and a passive portion so that the transformation of the pivoting movement of the cam into a displacement movement of the follower element, or vice versa, takes place over only the active portion of the track. 
         [0021]    In this manner, when the handle is actuated, the follower element first moves over the passive portion so that the second locking system is not actuated. The follower element then reaches the active portion of the track and moves along this portion. The second locking system is then actuated along the whole displacement of the follower element over the active portion and moves from a locked state to an unlocked state, or vice versa. When the follower element has travelled over the active portion of the track, it then again reaches the passive portion and moves along the latter so that the second locking system is no longer actuated. 
         [0022]    According to one feature of the invention, the linking means comprise a movable transmission member, comprising a first end connected to the first locking system and a second end connected to the cam, the actuation of the first locking system causing the translation by traction or compression of the transmission member. 
         [0023]    According to one embodiment of the invention, the follower element is placed at the second end of the transmission member, the displacement of the follower element over the active portion of the track causing the pivoting of the cam, the second locking system comprising a bolt connected to the cam, actuated by the pivoting of the latter. 
         [0024]    Therefore, the cam pivots only when the follower element is displaced along the active portion of the track, causing with it the displacement of the bolt. The cam therefore makes it possible to transform the displacement movement of the follower element into a movement of rotation of the cam and of displacement of the bolt. 
         [0025]    Preferably, the bolt can be moved in translation and is fitted with a finger inserted into an oblong hole arranged in the cam. 
         [0026]    The oblong hole makes it possible to compensate for the differences of trajectory between the linking zone of the cam with the bolt and the trajectory of the bolt. Specifically, the aforementioned linking zone moves on a curvilinear trajectory the center of which is the center of rotation of the cam while the bolt moves in a rectilinear manner. 
         [0027]    According to another embodiment of the invention, the cam is arranged in order to pivot over a determined travel when the handle is displaced, the cam interacting with the second locking system so as to achieve its actuation over only a portion of the total travel of the cam. 
         [0028]    Advantageously, the second end of the transmission member is connected to the cam so that the displacement of the transmission member rotates the cam, the second locking system comprising a bolt comprising the follower element, the pivoting of the cam causing the displacement of the follower element and of the bolt when the follower element is displaced over the active portion of the track. 
         [0029]    The cam therefore makes it possible to transform the rotary movement of the cam into a displacement movement of the follower element and of the bolt, when the follower element reaches the active portion of the track. 
         [0030]    According to one feature of the invention, the cam is mounted on the second locking system. 
         [0031]    The invention also relates to a nacelle comprising at least one locking device according to the invention. 
         [0032]    The invention also relates to an aircraft fitted with at least one nacelle according to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    In any case, the invention will be well understood with the aid of the following description with reference to the appended schematic drawing representing, as examples, several embodiments of this locking device. 
           [0034]      FIG. 1  is an exploded schematic view, in perspective, of the nacelle fitted with locking devices according to the invention. 
           [0035]      FIGS. 2 to 9  are views illustrating a first embodiment of the device, in which 
           [0036]      FIG. 2  is a front view of the second locking system in a first position; 
           [0037]      FIG. 3  is a front view of the first locking device, in the first position; 
           [0038]      FIGS. 4-5 ,  6 - 7  and  8 - 9  are views corresponding to  FIGS. 2-3 , respectively in three successive positions of the locking device; 
           [0039]      FIGS. 10 to 19  are views illustrating a second embodiment of the device, in which 
           [0040]      FIGS. 10 and 11  are views corresponding to  FIGS. 2 and 3 ; 
           [0041]      FIGS. 12-13 ,  14 - 15 ,  16 - 17  and  18 - 19  are views corresponding to  FIGS. 10-11 , respectively in four successive positions of the locking device; 
           [0042]      FIGS. 20-29  are views illustrating a third embodiment of the device, corresponding respectively to  FIGS. 10 to 19 . 
       
    
    
     DETAILED DESCRIPTION 
       [0043]      FIG. 1  represents an exploded view of the rear section of a nacelle. The latter comprises, as is known to those skilled in the art, a first and second movable elements  1 ,  2 , articulated at their top portion on a pylon of an aircraft, not shown. 
         [0044]    Each articulated element  1 ,  2  takes the general form of a hollow half-cylinder, delimiting two junction zones  3 ,  4  with the articulated element facing it, namely a top junction zone  3  and a bottom junction zone  4 . 
         [0045]    The bottom and top positions are also called respectively the  6  o′clock and  12  o′clock positions. 
         [0046]    The nacelle is fitted with a first and a second locking device  5 ,  6 . 
         [0047]    It should be noted that, for reasons of presentation, only two of these devices are shown. 
         [0048]    Each locking device  5 ,  6  comprises a first locking system  7  and a second locking system  8 , connected to the first by linking means  9  arranged to actuate the second locking system  8  by the actuation of the first  7 . 
         [0049]    Each locking system  7 ,  8  is mounted on the first movable element  1  and is capable of being locked to a corresponding retention member  10 ,  11 , mounted on the second movable element  2 . 
         [0050]    The first and second locking systems  7 ,  8  of each locking device  5 ,  6  are mounted respectively in the bottom and top junction zones  4 ,  3  of the first articulated element  1 . 
         [0051]    The structure and the operation of the first locking device  5  according to a first embodiment of the invention will now be described in greater detail with reference to FIGS.  2  to  9 . 8   
         [0052]    As shown in  FIG. 3 , the first locking system  7  comprises a control handle  12  designed to be actuated by an operator. The handle  12  is mounted pivotingly on a shaft  13  and comprises an opening  14 . The first locking system  7  also comprises an element  15  having a hook  16  close to a first end and mounted pivotingly at a second end on the shaft  13 . This element  15  also has an oblong opening  17  in its middle portion, as can be seen more particularly in  FIG. 7 . The hook  16  is designed to engage with the retention member  10  of the second articulated element  2  of the nacelle. 
         [0053]    The first locking system  7  also comprises a link rod  18  articulated at a first and a second end about a first and a second shaft  19 ,  20  protruding respectively into the opening  14  of the handle  12  and into the oblong opening  17  of the element  15  having the hook  16 . The shafts  19 ,  20  can be moved inside each of the openings  14 ,  17 . In addition, the second shaft  20  is fixed relative to the first articulated element  1  of the nacelle. 
         [0054]    The first locking system  7  also comprises a movement-transformation member  21  mounted pivotingly on the shaft  13  and articulated on the first shaft  19  of the link rod  18 . The movement-transformation member  21  also comprises an arm  22 . The linking means comprise a flexible cable  9  symbolized by a line for reasons of clarity of the drawing. The cable  9  has a first and a second end, the first end being mounted articulated on the free end of the arm  21 . 
         [0055]    As shown in  FIG. 2 , the second locking system  8  comprises a body  23  that is fixed relative to the first articulated element  1  of the nacelle. 
         [0056]    The body  23  comprises a slot  24  allowing the insertion of the corresponding retention member  11 , a bolt  25  being mounted movably in translation on the body, along an axis A perpendicular to the slot  24 , between a locked position in which the bolt  25  passes through the slot  24  or protrudes into the latter, as shown in  FIG. 2 , and an unlocked position in which the bolt  25  is fully housed inside the body  23  and does not or virtually does not protrude into the slot  24 , shown in  FIGS. 6 and 8 . 
         [0057]    The bolt  25  comprises a post  26  protruding perpendicularly to the axis A and to the slot  24 , through an oblong opening  27  arranged in the body  23  along the axis A so as to allow the displacement of the bolt  25 . 
         [0058]    The body  23  also comprises an oblong opening or a groove  28  extending obliquely relative to the slot  24  and to the oblong opening  27 , between a first end situated in the vicinity of the slot  24  and of the oblong opening  27  and a second end situated in the vicinity of an articulation shaft  29  the function of which is described below. 
         [0059]    The locking device also comprises sequencing means comprising a cam  30  of elongated shape, comprising a first and a second end. The cam  30  is mounted pivotingly at its first end on the body  23  of the second locking system  8 , about the shaft  29 . The cam  30  also comprises an oblong hole  31  at its second end, the post  26  of the bolt  25  protruding into the oblong hole so that the latter extends substantially perpendicularly to the axis A of displacement of the bolt  25 . 
         [0060]    The cam  30  also comprises a track  32  formed by an oblong opening in the general shape of a staircase step. The track  32  therefore has three successive portions, namely a first passive portion  33 , a second active portion  34  and a third passive portion  35 , the function of which is given in detail below. 
         [0061]    The cable  9 , shown schematically by a line, comprises a finger  36  at its second end, the finger  36  being inserted into the track  32  of the cam  30  and into the groove  28  of the body  23  so as to form a follower element. 
         [0062]    Described below are the successive steps for opening the locking device, illustrated in  FIGS. 2 to 9 . 
         [0063]      FIGS. 2 and 3  represent the locked position of the latter, in which the first and second locking systems  7 ,  8  are both locked. In this position, the handle  12  is in the closed position, that is to say brought closer to the element  15  having the hook  16 , the follower finger  36  being situated in the first passive portion  33  of the track  32 , at the end of the track. The cam  30  is placed in a first angular position in which the bolt  25  which is connected to it is in the top position, that is to say passes through the slot  24 . 
         [0064]    As shown in  FIGS. 4 and 5 , when the user actuates the handle  12  in order to open it, the arm  22  pivots in the counterclockwise direction in order to displace the cable  9  in translation, by pulling on the latter. The follower finger  36  is then displaced along the first passive portion  33  of the track  32 . During this displacement, the cam  30  does not pivot, the first passive portion  33  of the track  32  coinciding then with the groove  28  arranged in the body  23 . 
         [0065]    When the operator continues to actuate the handle  12 , the first shaft  19  of the link rod  18  butts against the edge of the opening  14  of the handle  12  and is operated by the movement of the latter. The link rod  18  is then displaced so that the second shaft  20  of the latter translates in the oblong opening  17  of the element  15  comprising the hook  16 . 
         [0066]    The aforementioned second shaft  20  being fixed, the element  15  comprising the hook  16  is displaced so that the retention element  10  begins to disengage from the hook  16 . In this position, the first locking system  7  is still locked since the retention element  10  is not completely disengaged from the hook  16 . 
         [0067]    Continuing the opening movement of the handle, the arm  22  continues to translate the cable  9  so that the follower finger  36  is displaced along the second active portion  34  of the track  32 , from one end to the other of the latter. As seen above, the second active portion  34  is oriented obliquely relative to the first passive portion  33  and the follower finger  36  is inserted into the groove  28  of the fixed body  23 . The cam  30  is therefore rotated in the counterclockwise direction about the shaft  29  and displaces the bolt  25  in the bottom position. During this displacement, the post  26  of the bolt  25  translates in the oblong hole  31  of the cam  30 , which makes it possible to compensate for the differences in trajectories between the curvilinear trajectory of the end of the cam  30  attached to the bolt  25  and the rectilinear trajectory A of the latter. 
         [0068]    As shown in  FIG. 6 , the bolt  25  is disengaged from the slot  24  when the follower finger  36  has traversed the active portion  34  of the track  32 . Therefore, the second locking system  8  is unlocked even when the first  7  is still locked, because the retention member  10  is still engaged in the hook  16 . 
         [0069]    As shown in  FIGS. 8 and 9 , when the operator continues to actuate the handle  12 , the retention element  10  is completely disengaged from the hook  16  so that the first locking system  7  is unlocked. As above, the arm  22  continues to translate the cable  9  so that the follower finger  36  is displaced along the third passive portion  35  of the track  32 . This passive portion  35  then extends along the axis of the groove  28  of the body  23  so that the displacement of the follower finger  36  does not cause the pivoting of the cam  30 . Consequently, the bolt  25  is not displaced. 
         [0070]    Therefore, as described above, the first locking device is sequenced. Specifically, when the handle  12  is opened, the operator first unlocks the second locking system  8 , then the first locking system  7 . This prevents the operating errors explained in the introduction part. 
         [0071]    It will be easy to understand that, when the handle  12  is closed, the operator first locks the first locking system  7  and then locks the second locking system  8 . 
         [0072]      FIGS. 10 to 19  illustrate a second embodiment also corresponding to the first locking device the position of which in the nacelle is shown in  FIG. 1 . 
         [0073]    To make it easier to understand, the elements have been designated by the same reference numbers as before. 
         [0074]    As appears in  FIG. 11 , the first locking system has a structure similar to that illustrated in  FIG. 3 . 
         [0075]    The second locking system is shown in  FIG. 10 . As before, the bolt  25  is mounted so as to be able to be displaced in the body  23 , the post  26  protruding outward from the bolt  25 . In addition, the cam  30  is also mounted pivotingly about the shaft  29 . 
         [0076]    In this embodiment, the cam  30  has a general shape of a quarter of a disk, comprising a first and a second adjacent edge  37 ,  38  substantially forming a right angle relative to one another, connected via a peripheral edge  39  in the arc of a circle. 
         [0077]    The cam  30  is mounted pivotingly close to the right-angle zone. 
         [0078]    The first edge  37  comprises, close to the right-angle zone, a lug  38  protruding outward, the free end of which is connected via an articulation shaft  39  to the second end of the cable  9 . 
         [0079]    Consequently, the displacement of the cable  9  causes the cam  30  to pivot about the shaft  29 . 
         [0080]    As before, the cam  30  comprises a track  32  in the form of an opening, having an active portion  34  and a passive portion  35 . 
         [0081]    The passive portion  35  of the track  32  extends in a parallel arc of a circle set back from the peripheral edge  39  of the cam  30  and of which the center corresponds to the shaft  29 . The active portion  34  of the track  32  extends substantially parallel to the first edge  37  of the cam  30 , from the passive portion  35  so as to form a continuous track. 
         [0082]    The post  26  of the bolt  25  is inserted into the track  32  and thus forms a follower element. 
         [0083]    As is shown successively in  FIGS. 10 to 15 , the opening of the handle  12  by the operator makes it possible to exert traction on the cable  9  via the arm so that the cable  9  rotates the cam  30  in the counterclockwise direction. During this rotation, the post  26  of the bolt  25  is displaced along the active portion  34 , translating the bolt  25  downward so as to open the second locking system  8 . 
         [0084]      FIG. 16  represents the second locking system  8  in the completely unlocked position in which the follower post  26 , having traversed all of the active portion  34  of the track, enters the passive portion  35 . It is then possible to engage or disengage the retention member  11  fixed to the second movable portion  2  of the nacelle. 
         [0085]    From this position, when the operator continues to open the handle  12  and consequently to pivot the cam  30 , the follower post  26  is displaced in the passive portion  35  of the track  32 . This displacement does not cause the displacement of the bolt  25 . 
         [0086]    As above, when the handle is displaced over the whole of its travel, as shown in  FIGS. 18 and 19 , the hook  16  is completely disengaged from the corresponding retention element  10  so as to unlock the first locking system  7 . 
         [0087]    This second embodiment therefore also allows sequencing between the actuation of the first and of the second locking system  7 ,  8  so that, when the handle  12  is opened, the operator first unlocks the second locking system  8  and then unlocks the first locking system  7 . 
         [0088]    As above, the locking of this device is obtained by the inverse succession of the aforementioned steps. 
         [0089]    A third embodiment is illustrated in  FIGS. 20 to 29 . This third embodiment corresponds to the second locking device  6  the position of which is illustrated in  FIG. 1 . For easier understanding, the elements have been designated by the same reference numbers as before. 
         [0090]    The first locking system  7  is shown in  FIG. 21 . The latter comprises a body  40  that is fixed relative to the movable element  1  and is fitted with a bolt  41  mounted so as to be displaceable in translation on the body, capable of being displaced between a first locked position shown in  FIG. 21  in which the bolt  41  traverses a slot  42  designed for the insertion of the corresponding retention member  10 , and an unlocked position shown in  FIG. 29  in which the bolt  41  is retracted relative to the slot  42 . 
         [0091]    The translation of the bolt  41  is actuated by the user, via a handle  12 , shown in  FIG. 1 , connected to the bolt  41  by a rod  43 . 
         [0092]    The second locking device  6  also comprises a movement-transformation member  44 , mounted on the first locking system  7 , making it possible to transform the translation movement of the handle  12  and of the bolt into a translation movement by traction or compression of the cable  9 . 
         [0093]    The movement-transformation element  44  is of elongated shape, comprises a first end mounted pivotingly on the body  40  of the first locking system, about a shaft  45 , and comprises a second end at which an opening  46  is arranged. According to one embodiment, the opening  46  comprises a passive portion and an active portion. 
         [0094]    In addition, the bolt  41  comprises a follower post  47  protruding into the opening  46 . 
         [0095]    The movement-transformation element  44  also has an arm  48  protruding outward at the first end, the free end of the arm being connected to the first end of the cable  9 . 
         [0096]    The second locking system  8  is illustrated in  FIG. 20 . In this embodiment, the cam  30  is mounted pivotingly about the shaft  29 , the second end of the cable  9  being connected to the cam  30  at the shaft  39 . 
         [0097]    The track  32  of the cam  20  has a shape similar to that of the second embodiment, that is to say comprises a passive portion  35  in the shape of an arc of a circle the center of which corresponds to the pivot shaft  29  of the cam  30 , from which a straight active portion  34  extends. 
         [0098]    The operation and the movement sequence of the second locking system  8  of this third embodiment of the invention are similar to those of the second embodiment described above. 
         [0099]    The operation of the second locking device  6  will now be described below. 
         [0100]    When the user pulls on the control handle  12 , the bolt is displaced downward, rotating the movement-transformation element  44  in the counterclockwise direction. The latter then translates the cable  9  connected to the cam  30 . The latter is therefore rotated in the counterclockwise direction, the follower post  26  of the bolt  25  traversing the active portion  34  of the track  32  so as to displace the bolt  25  downward, that is to say so as to unlock the second locking system  8 . The active portion  34  is extended by an overtravel forming an additional passive portion, necessary in order to compensate for the positioning differences between the various components. 
         [0101]    This position is shown in  FIG. 26 . The travel of the bolt  41  of the first locking system  7  and the shape of the opening  46  of the movement-transformation element  44  are arranged so that only a portion of the travel of the handle  12  necessary for completely opening the first locking system  7  is sufficient for the follower post  26  to traverse the active portion  34  of the track  32 , that is to say to unlock the second locking system  8 . 
         [0102]    When the user continues to pull on the handle  12 , the bolt  41  continues its translation movement downward until the latter reaches the unlocked position shown in  FIG. 29 . During this movement of the handle  12 , the cam  30  is pivoted so that the follower finger  26  of the bolt  25  of the second locking system  8  is displaced along the passive portion  35  of the track  32 , the bolt  25  then not being displaced in translation. 
         [0103]    As above, the unlocking of the second locking device is achieved in a sequenced manner, the locking being obtained by the inverse succession of the aforementioned steps. 
         [0104]    As it goes without saying, the invention is not solely limited to the embodiments of this locking device that have been described above as examples, but on the contrary it covers all the variants.

Summary:
The invention relates to a locking device ( 5, 6 ) comprising a first locking system ( 7 ) equipped with a control handle ( 12 ), intended to be actuated by an operator, characterized in that it includes a second locking system ( 8 ) connected to the first ( 7 ) by linking means ( 9 ) designed to actuate the second locking system ( 8 ) because of the actuation of the first ( 7 ), the first locking system ( 7 ) being actuated alternately between a locked state and an unlocked state by movement of the handle ( 12 ) over the totality of a defined course, the linking means ( 9 ) having sequencing means designed to actuate the second locking system ( 8 ), between a locked state and an unlocked state thereof respectively, during the displacement of the handle ( 12 ) over only part of the travel of the latter.