Abstract:
The invention concerns a system for opening and closing a door ( 50 ) for a landing gear ( 30 ) compartment ( 20 ) of an aircraft ( 10 ) having great positioning freedom. 
     According to the invention, the connecting means ( 60, 70, 81, 82 ) between the landing gear ( 30 ) and the door ( 50 ) include a first system forming an actuator ( 60 ) mounted on the landing gear ( 30 ) and a second system forming an actuator ( 70 ) mounted on the door ( 50 ), the two systems forming actuators ( 60, 70 ) being connected to each other by at least one fluid communication means ( 81, 82 ) such that actuating the first system forming an actuator ( 60 ) causes the actuation of the second system forming an actuator ( 70 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention concerns a system for opening and closing the door of an aircraft landing gear compartment. 
       BACKGROUND OF THE INVENTION 
       [0002]    The landing gear compartment is used to housing landing gear on any type of aircraft, in particular when the landing gear is placed under the fuselage of the aircraft. 
         [0003]    Usually, this landing gear compartment is closed by several doors. For example, and in reference to  FIG. 1 , the compartment  20  for the front landing gear  30  is in particular closed by:
       the front doors  40 , which open during the descent of the gear  30 , in particular to allow the leg  31  thereof to pass, and close after the exit of the gear  30  so as to preserve the aerodynamism of the fuselage  11  of the aircraft  10 , and   the back doors  50 , which open during the descent of the gear  30  and remain open as long as the gear  30  is out.       
 
         [0006]    A landing gear door is usually formed by a single-piece rigid panel. This panel is generally hinged on the aircraft structure around a pivoting axis offset towards the inside of the gear compartment in relation to said panel. More precisely, the panel is mounted secured to the gear, such that the exit and return of the gear cause the opening and closing of the panel, respectively. 
         [0007]    The pivoting of the door is usually obtained via a direct mechanical connection between the door and the gear. 
         [0008]    The direct connection consists of a single connecting rod mounted, on one hand, on the landing gear, for example on the leg, the beam or the strut, and on the other hand on the door. Thus, when the gear comes out, it pivots around an axis causing the movement of the connecting rod, which makes the door pivot into its opening position. In parallel, the return of the gear into the compartment causes the door to close. 
         [0009]    The use of a single connection does, however, have the drawback of presenting a limited freedom of positioning of the connecting rod, implying significant design constraints. 
         [0010]    Indeed, the connecting rod must be mounted on the gear on one hand and on the door on the other. 
         [0011]    Among these constraints, we sometimes see the obligation to arrange the connecting rod inclined relative to the door, due in particular to the reduced space in the landing gear bay and the kinematics of the landing gear and the door. 
         [0012]    One consequence is the low intensity of the restoring moment exerted by the connecting rod on the door, when the door is in the closed position. The door indeed undergoes very significant aerodynamic stresses that the connecting rod cannot completely balance. 
         [0013]    Thus, to pick up the stresses undergone by the door, the fittings attaching the door to the structure of the compartment, for example goosenecks, are reinforced and then have large dimensions. The problems of mass and bulk then arise. 
         [0014]    Moreover, before the landing gear comes out and when the front doors are open, the air rushes into the landing gear compartment and also exerts a very significant stress on the back doors. 
         [0015]    The back doors vibrate greatly, which causes, aside from noise problems, premature fatigue of the doors and the corresponding connecting rods. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0016]    The invention mainly. relates to a system for opening and closing a door of the landing gear compartment, the original design of which grants it great freedom of positioning. 
         [0017]    The system for opening and closing a door includes connecting means between the landing gear and the door designed to ensure the opening of the door when the gear comes out and the closing of the door when the gear goes back in. 
         [0018]    According to the invention, the connecting means includes a first system forming an actuator mounted on the landing gear and a second system forming an actuator mounted on the door, the two systems forming actuators being connected to each other by at least one fluid communication means such that the actuation of the first system forming an actuator causes the actuation of the second system forming an actuator. 
         [0019]    Thus, the system according to the invention has great positioning freedom and then makes it possible to adapt to the kinematic constraints and space management constraints in the landing gear compartment. 
         [0020]    Indeed, the door is not directly connected to the landing gear, but rather indirectly connected, via two systems forming actuators connected to each other by fluid communication means. 
         [0021]    This indirect connection offers an additional degree of freedom relative to the direct connection of the prior art. 
         [0022]    The system according to the invention indeed has two axes of translation corresponding to the natural axis of translation of each of said systems forming actuators themselves. These axes of translation are not necessarily oriented in a required position. Indeed, only a fastening point is defined for each system forming an actuator, the fastening point on the landing gear for the first system forming an actuator and the fastening point on the door for the second. Each system forming an actuator therefore has the freedom to be oriented in a suitable direction. 
         [0023]    As a result, it is in particular possible to mount the second system forming an actuator with an orientation that allows it to balance the aerodynamic stresses undergone by it. 
         [0024]    Thus, the second system forming an actuator can also be mounted on the landing gear compartment. 
         [0025]    The second system forming an actuator can be arranged substantially perpendicular, locally, to the door when said door is closed. 
         [0026]    The aerodynamic stresses exerted on the door are then balanced by the second system forming an actuator. It is no longer necessary to reinforce or oversize the goosenecks, which makes it possible to meet the mass and bulk requirements specific to aeronautics. 
         [0027]    Moreover, the system according to the invention has the advantage of not making the actuation of the door by dedicated control means more complex. Indeed, the actuation of the second system forming an actuator is controlled by the actuation of the first system forming an actuator, and not by additional means. 
         [0028]    Advantageously, the systems forming actuators are two-way cylinders. 
         [0029]    According to an embodiment of the invention, each cylinder of said systems forming actuators includes a front chamber and a back chamber, the front chamber receives a so-called actuating rod. A first pipe ensures the fluid communication between said front chambers and a second pipe ensures the communication between said back chambers. 
         [0030]    In another embodiment of the invention, the first pipe ensures the fluid communication between the front chamber of the first system forming an actuator and the back chamber of the second system forming an actuator and the second pipe ensures the communication between the back chamber of the first system forming an actuator and the front chamber of the second system forming an actuator. 
         [0031]    Preferably, the pipes are flexible. 
         [0032]    The actuators can have a double rod. 
         [0033]    Each actuator preferably comprises a fastening portion that extends along the axis of symmetry of the cylinder from the back chamber. 
         [0034]    Each system forming an actuator can comprise a volumetric compensator. 
         [0035]    Advantageously, the first system forming an actuator, the second system forming an actuator and the fluid communication means together form at least one closed fluid circuit. The closed fluid circuit(s) thus formed do not fluidly communicate with the handler device of the landing gear, the latter ensuring the exit and return of the landing gear. 
         [0036]    The invention also concerns an aircraft including a system for opening and closing a door having any one of the features just defined. 
         [0037]    Other advantages and features of the invention will appear in the non-limiting detailed description below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    We will now describe, as non-limiting examples, embodiments of the invention, in reference to the appended drawings, in which: 
           [0039]      FIG. 1 , already described, is a general perspective and side view of the front of an aircraft whereof the front landing gear is out; 
           [0040]      FIG. 2  is a perspective view of the system for opening and closing a door according to one embodiment of the invention, for which the landing gear is in; 
           [0041]      FIG. 3  is a perspective view of the system for opening and closing the door according to the preceding embodiment of the invention, for which the landing gear is out; 
           [0042]      FIG. 4  is a diagrammatic cross-sectional illustration of two hydraulic actuators of the system for opening and closing the landing gear compartment door according to one embodiment of the invention; 
           [0043]      FIGS. 5A and 5B  are a diagrammatic cross-sectional illustration of the system according to the preceding embodiment, mounted on the landing gear and on the door, when the landing gear is in ( FIG. 5A ) and out ( FIG. 5B ). 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]      FIGS. 2 and 3  show perspective views of the system for opening and closing a door according to one embodiment of the invention, when the landing gear is in and out, respectively. The landing gear is not shown in its entirety so as to simplify the figures. 
         [0045]    In this embodiment, the door  50  is a back door of the compartment  20  of the landing gear  30 . The door  50  remains open as long as the landing gear is out. Moreover, its opening and closing movement is synchronized to the exit and return movement of the landing gear, respectively. 
         [0046]    The landing gear compartment  20  includes a rigid structure  21  made up of at least one central wall  22 A and side walls  22 B, as well as a ceiling wall (not shown). The side walls  22 B each support a back door  50 . 
         [0047]    The landing gear  30  in particular includes a leg  31  provided with a beam  32  whereof the ends are connected to the leg  31  by reinforcing arms  33 . The beam  32  ensures the fastening of the landing gear  30  to the structure  21  of the compartment  20  and constitutes an axis of rotation Y of the leg  31 . 
         [0048]    A handler device of the landing gear  30  (not shown) is provided to ensure the exit and return of the landing gear  30 . The handler device can comprise a hydraulic handler actuator, connected to the leg  31 , which can be actuated by a hydraulic pump. 
         [0049]    At least one back door  50  is provided to close the landing gear  30  compartment  20  when the landing gear is in. A single door  50  is shown in  FIGS. 2 and 3 . 
         [0050]    The door  50  is pivotably mounted on a side wall  22 B via goosenecks  52 . The pivoting of the door  50  is done around an axis of rotation X. 
         [0051]    The axis of rotation X is substantially orthogonal to the axis of rotation Y. The axis of rotation X of the door is substantially parallel to the longitudinal axis of the aircraft. 
         [0052]    The system for opening and closing the door  50  according to the invention includes a first system forming an actuator  60 , called landing gear actuator, and a second system forming an actuator  70 , called door actuator. 
         [0053]    Each actuator  60  and  70  comprises an actuator body  61 ,  71  and an actuating rod  62 ,  72 . The actuating rod moves in translation relative to the actuator body  61 ,  71  along an axis of symmetry of the actuator body. The structure of the actuators  60  and  70  is described in detailed below. 
         [0054]    The landing gear actuator  60  is mounted on one of the members of the landing gear  30 , for example, the leg  31 , the reinforcing arms  33 , or the strut (not shown). In the embodiment illustrated in  FIGS. 2 and 3 , the landing gear actuator  60  is mounted on a reinforcing arm  33  via the end of the actuating rod  62 . 
         [0055]    The body  61  of the landing gear actuator  60  is preferably mounted on the structure  21  of the landing gear compartment  20 , for example on the ceiling wall, or on the central wall  22 A as illustrated in  FIGS. 2 and 3 . 
         [0056]    The fastenings of the rod  62  and the actuator body  61  can be pivoting or like ball joint. 
         [0057]    The door actuator  70  is mounted on the door  50  of the landing gear compartment  20 . As shown in  FIG. 3 , it can be mounted on different locations of the door  50 , for example substantially at the center of gravity of the door, or near an edge  53  opposite the fastening edge  54  of the goosenecks  52 . These examples of locations for mounting the door actuator  70  make it possible to limit the effects of vibrations on the door  50 . In the embodiment illustrated in  FIGS. 2 and 3 , the door actuator  70  is mounted via the end of the actuating rod  72  on the door substantially near a lateral edge  55 . 
         [0058]    Preferably, the actuating rod  72  is oriented substantially perpendicularly, locally, relative to the door  50 , when said door is closed. It can be oriented so as to form, relative to the closed door  50 , a solid angle substantially between 0 and for example 2 steradians. 
         [0059]    The body  71  of the door actuator  70  is preferably mounted on the structure  21  of the landing gear compartment  20 , for example on the ceiling wall, or on a side wall  22 B as shown in  FIGS. 2 and 3 . 
         [0060]    The fastenings of the rod  72  and the actuator body  71  can be pivoting or like ball joint. 
         [0061]    In reference to  FIG. 4 , the body  61 ,  71  of the actuators  60  and  70  includes a cylinder  63 ,  73 , inside which a piston  64 ,  74  moves connected to the actuating rod  62 ,  72 . The piston  64 ,  74  thus defines two chambers sealed relative to each other, a so-called front chamber  63 A,  73 A and a so-called back chamber  63 B,  73 B. The front chamber  63 A,  73 A differs from the back chamber  63 B,  73 B in that it slidingly houses the actuating rod  62 ,  72 . 
         [0062]    In the embodiment of the invention, the actuator body  61 ,  71  also comprises a fastening portion  65 ,  75  that extends along the axis of symmetry of the cylinder  63 ,  73  from the back chamber  63 B,  73 B. The actuators  60  and  70  can be mounted, respectively, on the landing gear and on the door, at their fastening part  65 ,  75 . Preferably, the fastening point  66 ,  76  is situated on the axis of symmetry of the cylinder  63 ,  73 . 
         [0063]    The actuators  60  and  70  are advantageously two-way cylinders. Thus, they can be actuated in an exit and return direction of the respective actuating rods  62 ,  72 . The actuators  60  and  70  are connected to each other such that the actuation of the landing gear actuator  60  causes the actuation of the door actuator  70 . The actuation of the door actuator  70  is preferably automatic, i.e. directly controlled by the actuation of the landing gear actuator  60 . Thus, it does not require additional control means relative to those ensuring the actuation of the actuator  60 . 
         [0064]    To connect the actuators  60  and  70  to each other, pipes  81 ,  82  are provided to ensure fluid communication between the front chambers  63 A,  73 A and back chambers  63 B,  73 B of the actuators. 
         [0065]    The pipes are preferably flexible to adapt to the space management constraints of the landing gear bay  20 . 
         [0066]    In the example diagrammatically illustrated in  FIG. 4 , a first hose  81  connects the front chamber  63 A of the landing gear actuator  60  to the front chamber  73 A of the door actuator  70 . A second hose  82  connects the back chamber  63 B of the landing gear actuator  60  to the back chamber  73 B of the door actuator  70 . 
         [0067]    The pistons  64 ,  74  are arranged in the cylinders  63 ,  73  such that the sum of the volumes of the front chambers  63 A and  73 A and the hose  81  is equal to that of the volumes of the back chambers  63 B and  73 B and the hose  82 . The volume of the hoses  81  and  82  may be overlooked before the volumes of the chambers. 
         [0068]    Moreover, it is advantageous to use actuators  60  and  70  with double rods to ensure the equality of the maximum volumes of the front chambers  63 A,  73 A and back chambers  63 B,  73 B. The maximum volume of a chamber is defined when the piston  64 ,  74  is in either stop position. 
         [0069]    Preferably, the actuators  60  and  70  are hydraulic actuators that for example contain oil, or any other suitable liquid, which is preferably incompressible. They may, however, be pneumatic actuators. In the case where the fluid used is compressible, each actuator  60 ,  70  advantageously includes a volumetric compensator, so as to correct the volume variations of the fluid contained in the chambers due to thermal effects. 
         [0070]    The operating principles of the system for opening and closing a door is as follows, in reference to  FIGS. 5A and 5B , which very diagrammatically illustrate a system for opening and closing a door mounted, on one hand, on the landing gear  30 , and on the other hand, on the door  50 . 
         [0071]    In  FIG. 5A , the landing gear  30  is in the in position and the door  50  is in the closed position. 
         [0072]    The landing gear cylinder  60  is mounted on the landing gear leg  31 , in an out configuration of the actuating rod  62 . It is connected to the door actuator  70 , mounted on the door  50  in an in configuration of the actuating rod  72 . 
         [0073]    The hoses  81  and  82  ensure fluid communication between the two cylinders  60  and  70 . 
         [0074]    In reference to  FIG. 5B , when the landing gear  30  descends under the action of the handler device of the landing gear (not shown), it rotates around its axis of rotation Y and actuates the landing gear actuator  60 . 
         [0075]    The actuating rod  62  is then moved into its in position. The return of the actuating rod  62  inside the cylinder  63  causes the volume of the front chamber  63 A to increase and the volume of the back chamber  63 B to decrease. The piston  64  then exerts pressure on the fluid contained in the back chamber  63 B, which is moved outside the back chamber  63 B. The fluid fills, via the hose  82 , the back chamber  73 B of the door cylinder  70 . 
         [0076]    The back chamber  73 B of the door cylinder  70  is filled with fluid that exerts, at the same time, pressure on the piston  74 . The piston  74  moves in the direction of the exit of the actuating rod  72 . In parallel, the fluid contained in the front chamber  73 A is moved, via the hose  81 , in the front chamber  63 A of the landing gear cylinder  60 . 
         [0077]    Thus, the actuating rod  72  of the door actuator  70  moves into the out position, and causes the door to rotate around its axis X and thus to open. 
         [0078]    Conversely, the raising handling of the landing gear  30  causes the landing gear actuator  60  to be actuated and its rod  62  to come out. The movement of the rod  62  causes the movement, in the direction opposite the direction previously described, of the pistons  64  and  74 , and of the fluids contained in the respective chambers. The actuating rod  72  of the door cylinder  70  is then moved in the in direction. Thus, the door actuator  70  exerts a pull force on the door  50  and causes it to close. 
         [0079]    In one alternative embodiment of the invention not shown, the landing gear cylinder  60  is oriented such that the actuating rod  62  is in the in position, and no longer out as before, when the landing gear  30  is raised. 
         [0080]    Thus, the descent of the landing gear  30  causes the actuation of the actuator  60  by moving the actuating rod  62  into its out position. 
         [0081]    The hose  81  is arranged so as to ensure fluid communication between the front chamber  63 A of the landing gear cylinder  60  with the back chamber  73 B of the door  70 . Likewise, the hose  82  ensures fluid communication between the back chamber  63 B of the landing gear actuator  60  with the front chamber  73 A of the door actuator  70 . 
         [0082]    The operating principle is then similar to that previously described. 
         [0083]    Moreover, it should be noted that the technical characteristics (diameter of the cylinder, travel of the piston) can be adapted for each actuator  60 ,  70  potentially as a function of the space constraints of the compartment  20 . Thus, the travel of the pistons  64 ,  74  may not be identical, the diameter of the cylinders and  73  is then dimensioned such that the fluid volume displaced in a first hose is always identical to the volume displaced in the second hose.