Abstract:
A linkage mechanism for controlling an aircraft landing gear hatch door includes a primary torsion tube having a first portion located inside a landing gear hatch and a second portion outside the landing gear hatch. A first drive apparatus transfer the driving force of a landing gear support column to the primary torsion tube. A secondary torsion tube has an inner end portion located inside the hatch and an outer end portion located outside the hatch. A second drive apparatus is located outside the landing gear hatch and connects the primary torsion tube and the secondary torsion tube outside the hatch. Two third drive apparatuses are connected between the inner end portion of the secondary torsion tube and one of the hatch doors.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to International Application Serial No. PCT/CN2014/084769, filed Aug. 20, 2014, which claims priority to Chinese Application No. 201310513351.8, filed Oct. 25, 2013. International Application Serial No. PCT/CN2014/1084769 is hereby incorporated herein in its entirety for all purposes by this reference. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present invention relates to a linkage mechanism for driving an aircraft landing gear bay door so as to obtain the linkage between bay doors and an aircraft landing gear, and belongs to the field of landing gear structure design. 
       BACKGROUND OF THE DISCLOSURE 
       [0003]    Generally, the aircraft landing gear bay doors of an aircraft have two kinds of structures: an independent structure and a linkage structure. The independent structure is designed in such a way that the bay doors of the landing gear are separately controlled to open and close independent of the retraction and release of the landing gear. The bay doors are opened before the retraction and release of the landing gear, and are closed after the retraction and release of the landing gear. The linkage structure is designed in such a way that a driving point is set on a retraction and release member of the landing gear such as a landing gear strut or a drag strut, and the bay doors are forced to open and close through a linkage mechanism by virtue of the movement of the retraction and release member of the landing gear, thereby obtaining a function of opening the bay door before the retraction and release of the landing gear and closing the bay door after the retraction and release of the landing gear. However, whatever the structures of the bay doors, they are arranged in a landing gear bay and have a symmetric configuration. In order to avoid the interference during the retraction and release of the landing gear, the landing gear bay must have enough space to arrange the linkage mechanism for driving the bay doors. 
         [0004]    WO 20101063110A1 discloses a driving device for a bay door of a landing gear with a linkage between the landing gear and the bay door. The driving device is arranged in a bay of the landing gear and has a symmetric configuration. However, in this patent, two bay doors of the bay of the landing gear are driven separately by two symmetric structures on two sides, that is, the two bay doors are respectively equipped with a driving mechanism which needs to be installed and adjusted, thereby causing a nonsynchronous movement between two driving mechanisms. 
         [0005]    Patent application CN 102470920 A discloses a device for driving a bay door of an aircraft landing gear with a linkage between the door and the aircraft landing gear. The device is also arranged in the aircraft landing gear bay and has a symmetric configuration. In this driving device, a driven landing gear strut forces a panel of a breaker strut to pivot, thereby causing a generator lever  20 ′ linked with the panel to pivot. This movement of the generator lever  20 ′ is transmitted to a rocker lever  23 ′ by a transferring rod  24 ′, thus causing the rocker lever to pivot in a direction that tends to push against left and right links  25   a ′ and  25   b ′ symmetrically arranged and associated with the left and right bay doors, and thus open the doors. However, the movement needs to be transmitted from the landing gear strut to the transferring rod and to the rocker lever via an intermediate part such as the breaker strut, thus, on one hand, this device takes a relatively large space in the bay of the aircraft landing gear; on the other hand, the force cannot be transmitted directly, thereby affecting the force transferring performance. 
       BRIEF SUMMARY 
       [0006]    The present invention provides a linkage mechanism used for driving an aircraft landing gear bay door, which can save the space in the landing gear bay and obtain a good force transferring performance. 
         [0007]    For this purpose, according to one aspect of the present invention, the present invention provides a linkage mechanism used for driving an aircraft landing gear bay door, the linkage mechanism being suitable for connecting with bay doors and a landing gear and converting the back-and-forth movement of the landing gear between a retracted position inside of the landing gear bay and a released position outside of the landing gear bay, respectively into the back-and-forth movement of the bay doors between a closed position and an open position, the linkage mechanism comprising: 
         [0008]    a primary torsion tube comprising a first portion located inside a landing gear bay and a second portion outside the landing gear bay; 
         [0009]    a first drive apparatus connected between the first portion and a landing gear strut so as to transfer the driving force of the strut to the primary torsion tube; 
         [0010]    a secondary torsion tube comprising an inner end portion located inside the bay and an outer end portion outside the bay; 
         [0011]    a secondary drive apparatus connected between the outer end portion and the second portion for transmitting a torque of the primary torsion tube to the secondary torsion tube; and 
         [0012]    two third drive apparatuses respectively connected between the inner end portion of the secondary torsion tube and one of the bay doors so as to enable the bay doors to be driven by the secondary torsion tube for accomplishing the opening and closing movement. 
         [0013]    According to this aspect of the present invention, the force transferring structure from the primary torsion tube to the secondary torsion tube is positioned outside of the landing gear bay, so the arrangement space in the landing gear bay can be saved to the utmost extent; the interference risk between the motion mechanisms can be reduced; the driving force of the landing gear strut is directly transmitted to the primary torsion tube via a first rod and a primary inner crank without being transmitted through the breaker strut as in the prior art, so the force transferring performance is good; and the torque is transmitted via one side, i.e., the torque is transmitted via one secondary torsion tube to control two bay doors simultaneously, so the quantity of parts is reduced, the space is saved, and the motion synchronism of the doors is high. 
         [0014]    The first drive apparatus comprises a primary inner crank and a first rod, one end of the primary inner crank is securely connected to the first portion of the primary torsion tube, and two ends of the first rod are pivotally connected between the other end of the primary inner crank and the strut. 
         [0015]    Preferably, the first rod is a L-shaped rod. The L-shaped rod may better prevent the linkage mechanism from interfering with the landing gear strut during the moving process. 
         [0016]    Preferably, the L-shaped rod comprises a body portion and a moving portion removably connected with each other. The L-shaped rod has a segmented design, and the length of the rod may be adjusted depending on the position of the whole machine. 
         [0017]    Preferably, the body portion has a sliding hole and a first rack structure, and the moving portion has a screw hole and a second rack structure. The sliding hole is configured in such a way that a screw passing through the screw hole may slide along the sliding hole so as to adjust a connecting position of the body portion and the moving portion. In the connecting position, the first rack structure is engaged with the second rack structure, and the body portion and the moving portion are securely connected by the screw passing through the screw hole and the sliding hole. This configuration can change the connecting position by changing the engaging position of the rack structures so as to change the length of the rod, thereby further adjusting the position of the whole machine. 
         [0018]    Preferably, the primary inner crank and the first portion of the primary torsion tube are connected with each other through the bolt by virtue of their respective lug structures. This flange type connecting structure enables the bolt to only suffer a shear force, thus each bolt bears a balanced force, so as to obtain a high strength and a good force transmission performance. 
         [0019]    Preferably, the secondary drive apparatus comprises: a primary outer crank having one end securely connected to the second portion of the primary torsion tube; a secondary outer crank having one end securely connected to the outer end portion of the secondary torsion tube; and an intermediate rod having two ends pivotally connected between the other end of the primary outer crank and the other end of the secondary outer crank. 
         [0020]    Preferably, each third drive apparatus comprises: a secondary inner crank having one end securely connected to the inner end portion of the secondary torsion tube; and a door rod having two ends pivotally connected between the other end of the secondary inner crank and one of the bay doors. 
         [0021]    More preferably, the secondary inner crank and the inner end portion of the secondary torsion tube are connected with each other through the screw by virtue of their respective lug structures. 
         [0022]    Preferably, the inner end portion of the secondary torsion tube are supported on two side walls of the landing gear bay by a ball bearing device, and the first portion and the second portion of the primary torsion tube are respectively supported on one side wall of the landing gear bay and an aircraft supporting structure outside of the side wall by a ball bearing device. Since the two ends of each torsion tube are fixed, this fixing form with two ends simply supported can better provide a supporting function to the torsion tubes and ensure a stable rotation of the torsion tubes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Other characteristics and advantages will become apparent from the following description of the invention. In the figures, the same reference signs indicate the same or similar parts, in which: 
           [0024]      FIG. 1  is a perspective view of a mechanical linkage mechanism for driving an aircraft landing gear bay door in the prior art; 
           [0025]      FIG. 2  is a schematic perspective view of a linkage mechanism for driving an aircraft landing gear bay door according to a preferred embodiment of the present invention; 
           [0026]      FIG. 3  is a schematic view showing the installation of the linkage mechanism for driving the aircraft landing gear bay as shown in  FIG. 2 ; 
           [0027]      FIG. 4A  is an enlarged view of a L-shaped rod of the linkage mechanism or driving the aircraft landing gear bay as shown in  FIG. 2 ; 
           [0028]      FIG. 4B  is an exploded view of the L-shaped rod as shown in  FIG. 4A ; 
           [0029]      FIG. 4C  is an enlarged view of portion A of the L-shaped rod as shown in  FIG. 4A ; 
           [0030]      FIG. 5  is a schematic view showing the connection structure of a primary inner crank and a primary torsion tube of the linkage mechanism for driving the aircraft landing gear bay as shown in  FIG. 2 ; 
           [0031]      FIG. 6  is a perspective view of an landing gear equipped with the linkage mechanism for driving the aircraft landing gear bay as shown in  FIG. 2 , wherein the landing gear is shown in a released position; 
           [0032]      FIG. 7  is a schematic view showing the landing gear of  FIG. 6  in an intermediate position; and 
           [0033]      FIG. 8  is a schematic view showing the landing gear of  FIG. 6  in a retracted position. 
       
    
    
     REFERENCE SIGNS 
       [0034]      
         [0000]    
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 100 
                 linkage mechanism 
                   
                   
               
               
                 10 
                 primary torsion tube 
               
               
                 103 
                 torsion tube lug structure 
               
               
                 11 
                 primary inner crank 
                 113 
                 crank lug structure 
               
               
                 12 
                 first rod 
               
               
                 120 
                 body portion 
                 121 
                 moving portion 
               
               
                 123 
                 sliding hole 
                 124 
                 first rack structure 
               
               
                 125 
                 screw hole 
                 126 
                 screw 
               
               
                 13 
                 primary outer crank 
               
               
                 15 
                 bolt 
               
               
                 20 
                 secondary torsion tube 
               
               
                 21 
                 secondary outer crank 
               
               
                 22 
                 left inner crank 
                 23 
                 right inner crank 
               
               
                 24 
                 left door rod 
                 25 
                 right door rod 
               
               
                 30 
                 intermediate rod 
               
               
                 200 
                 landing gear 
               
               
                 201 
                 strut 
               
               
                 300 
                 aircraft supporting structure 
               
               
                 401 
                 left door 
                 402 
                 right door 
               
               
                 403 
                 side wall 
               
               
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0035]    The following description will describe the implementing and the applying of the detailed embodiments of the present invention. However, it should be appreciated that the described embodiments are only used to illustrate the special form for implementing and applying the present invention in an exemplary manner, rather than limit the scope of the present invention. 
         [0036]    In the following description, the attached drawings are referred to. The drawings constitute a part of the present invention, and some specific embodiments for implementing the present invention are shown by way of example in the drawings. In this regard, some orientation terms, such as “left”, “right”, “top”, “bottom”, “front”, “back”, “guide”, “forwards”, and “backwards”, are used with reference to the directions shown in the drawings. Thus, the members of the embodiments of the present invention may be arranged in different directions, and the orientation terms are used as example rather than limitation. 
         [0037]      FIGS. 2 and 3  illustrate a linkage mechanism  100  for driving an aircraft landing gear according to a preferred embodiment of the present invention. The linkage mechanism  100  is suitable for connecting with the bay doors and the landing gear and converting the back-and-forth movement of the landing gear between a retracted position inside of the landing gear bay and a released position outside of the landing gear bay, respectively into a back-and-forth movement of the bay doors between a closed position and an open position. The linkage mechanism  100  comprises a primary torsion tube  10  comprising a first portion positioned in a landing gear bay and a second portion positioned outside the landing gear bay; a first drive apparatus connected between the first portion and a strut  201  of the landing gear  200  in order to transmit the driving force of the strut  201  to the primary torsion tube  10 ; a secondary torsion tube  20  comprising an inner end portion positioned in the landing gear bay and an outer end portion positioned outside the landing gear bay; a secondary drive apparatus connected between the outer end portion of the secondary torsion tube  20  and the second portion of the primary torsion tube  10  for transmitting a torque of the primary torsion tube  10  to the secondary torsion tube  20 ; and two third drive apparatuses respectively connected between the inner end portion of the secondary torsion tube and one of bay doors so as to enable the bay doors to be driven by the secondary torsion tube for accomplishing the opening and closing movement. 
         [0038]    Stilling referring to  FIGS. 2 and 3 , in this embodiment, the first drive apparatus preferably comprises a primary inner crank  11  and a first rod  12 . One end of the primary inner crank  11  is securely connected to the first portion of the primary torsion tube  10 , and the two ends of the first rod  12  are pivotally connected between the other end of the primary inner crank  11  and the strut  201 . 
         [0039]    As clearly shown in  FIG. 2 , the secondary drive apparatus preferably comprises a primary outer crank  13 , a secondary outer crank  21  and an intermediate rod  30 . One end of the primary outer crank  13  is securely connected to the second portion of the primary torsion tube  10 ; one end of the secondary outer crank  21  is securely connected to the outer end portion of the secondary torsion tube  20 ; and the two ends of the intermediate rod are pivotally connected between the other end of the primary outer crank  13  and the other end of the secondary outer crank  21 . 
         [0040]    Still referring to  FIGS. 2 and 3 , the two third drive apparatuses are a left drive apparatus and a right drive apparatus respectively. The left drive apparatus comprises a left inner crank  22  and a left door rod  24 , one end of the left inner crank  22  is securely connected to the inner end portion of the secondary torsion tube  20 , and two ends of the left door rod  24  are pivotally connected between the other end of the left inner crank  22  and a left door  401  (not shown). The right drive apparatus comprises a right inner crank  23  and a right door rod  25 , one end of the right inner crank  23  is securely connected to the inner end portion of the secondary torsion tube  20 , and the two ends of the right door rod  25  are pivotally connected between the other end of the right inner crank  23  and a right door  402 . 
         [0041]    As shown in  FIGS. 4A, 4B and 4C , in this embodiment, the first rod  12  is preferably a L-shaped rod and comprises a body portion  120  and a moving portion  121  removably connected with each other, that is to say, the first rod  12  has segmented design. The body portion  120  is provided with a sliding hole  123  and a first rack structure  124 , and the moving portion  121  is provided with a screw hole  125  and a second rack structure (not shown). The sliding hole  123  is configured in such a way that a screw  126  passing through the screw hole  125  may slide along the sliding hole  123  so as to adjust a connecting position of the body portion  120  and the moving portion  121 . In the connecting position, the first rack structure  124  is engaged with the second rack structure, and the body portion  120  and the moving portion  121  are securely connected by the screw  126  passing through the screw hole  125  and the sliding hole  123 . This configuration can change the connecting position by changing the engaging position of the two rack structures so as to change the length of the first rod  12 , thereby further adjusting the position of the whole machine. However, it should be appreciated that the first rod  12  may also be designed as a straight rod or other rods in case that the space in the landing gear bay is enough. 
         [0042]    As shown in  FIG. 5 , in this embodiment, the primary inner crank  11  preferably has a crank lug structure  113 , and the primary torsion tube  10  preferably has a torsion tube lug structure  103 , thus the primary inner crank  11  and the primary torsion tube  10  are connected through a bolt  15  by virtue of their respective lug structures. This flange type connecting structure enables the bolt  15  to only suffer a shear force, thus each bolt  15  bears a balanced force, so as to obtain a high strength and a good force transmission performance. Although  FIG. 5  shows the connection structure between the primary inner crank  11  and the primary torsion tube  10 , it should be appreciated that the connection structure between the left inner crank  22 , the right inner crank  23  and the secondary torsion tube  20  may also be implemented through the bolt by virtue of their respective lug structures. 
         [0043]    In this embodiment, the secondary torsion tube  20  is preferably supported on two side walls of the landing gear bay by a ball bearing device (not shown) in the interior of the left inner crank  22  and between the right inner crank  23  and the secondary outer crank  21 . Further, the primary torsion tube  10  is supported on a corresponding side wall  403  of the landing gear bay by a ball bearing device between the primary inner crank  11  and the primary outer crank  13 , and meanwhile, and the second portion of the primary torsion tube  10  in the landing gear bay is also preferably supported on an aircraft supporting structure  300  outside of the side wall  403  by a ball bearing device. Since the two ends of each torsion tube  10 ,  20  are fixed, this fixing form with two ends simply supported can better provide a supporting function to the torsion tubes  10 ,  20  and ensure a stable rotation of the torsion tubes  10 ,  20 . 
         [0044]    Returning to  FIG. 3 , although the outer end portion of the primary torsion tube  10  is fixed on the aircraft supporting structure  300  in a tripod form, it should be appreciated that the aircraft supporting structure  300  for fixing the primary torsion tube  10  is not limited to this structure, as long as it can support and fix the primary torsion tube  10  and prevent the primary torsion tube  10  that passes through the side wall  403  of the landing gear bay from swinging. 
         [0045]    The following description will introduce the operating principle of the linkage mechanism in this embodiment with reference to  FIGS. 6-8  and  FIGS. 2-3 . 
         [0046]    During the process of the landing gear  200  moving from a released position (see  FIG. 6 ) to a retracted position (see  FIG. 8 ) or from the retracted position to the released position ( FIG. 7  shows an intermediate position), the strut  201  of the landing gear  200  forces the primary inner crank  11  to rotate via the first rod  12 , and the primary torsion tube  10  transmits the torque of the primary inner crank  11  to the primary outer crank  13 . Then, the primary outer crank  13  forces the secondary outer crank  21  to rotate via the intermediate rod  30 , and the secondary torsion tube  20  transmits the torque to the left inner crank  22  and the right inner crank  23  simultaneously. Then, the two secondary inner cranks force the left door  401  and the right door  402  to move simultaneously via the left door rod  24  and the right door rod  25 . 
         [0047]    The linkage mechanism in this embodiment further has the following features: the linkage mechanism  100  is connected by two level cranks, and transmits the aerodynamic load (i.e., aerodynamic drag) of the doors to the landing gear strut using lever principle of the cranks, which effectively reduces the inhibition of the aerodynamic load of the doors to the normal retraction and release and emergency release of the landing gear and obtain a good force transferring performance. 
         [0048]    It should be appreciated that the linkage mechanism of the present invention can be widely applied to the airplane, such as a front door of a front landing gear of an airliner, or a door of a center main landing gear of a wide-body airliner. 
         [0049]    The above illustrates and describes basic principles, main features and advantages of the present invention. Those skilled in the art should appreciate that the above embodiments do not limit the present invention in any form. Technical solutions obtained by equivalent substitution or equivalent variations all fall within the scope of the present invention.