Abstract:
To provide an aircraft pylon capable of being mounted to a wing without exertion of preload while ensuring that redundancy is provided in the pylon. An aircraft pylon  50  includes: a pylon strut  11  for supporting an engine of an aircraft; a pin joint mechanism for connecting the pylon strut  11  to a main wing of the aircraft; a link member  15  disposed between the pylon strut  11  and the main wing of the aircraft, wherein the link member  15  includes a collection of plural independent link elements.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an aircraft pylon. 
     2. Description of the Related Art 
     An engine of an aircraft is mounted to a wing via a pylon comprising a structural member called a pylon strut (see, for example, Japanese Patent Laid-Open No. 2011-116186.). 
     As shown in  FIG. 4 , a pylon strut  110  which constitutes a pylon  500  is provided on an undersurface of a wing  100  so as to extend toward a front in a flying direction. In an engine  200 , a fan section  200   a  at the front is mounted to an undersurface of the pylon strut  110  by a front engine mount  300 , and a core section  200   b  at the rear is mounted to the undersurface of the pylon strut  110  by a rear engine mount  400 . 
     As described above, the pylon  500  is an element connecting the engine  200  to the wing  100 . Thus, redundancy is provided in a mounting structure between the pylon strut  110  and the wing  100  to ensure safety. That is, the pylon strut  110  is pin jointed at an attachment point  111 , which is a reference point, to the wing  100 . The pylon strut  110  is also pin jointed with a first link  113  and a second link  115  to the wing  100 . The first link  113  is pin jointed at an attachment point  113   a  to the pylon strut  110 , and is pin jointed at an attachment point  113   b  to the wing  100 . The second link  115  is pin jointed at an attachment point  115   a  to the pylon strut  110 , and is pin jointed at an attachment point  115   b  to the wing  100 . 
     Thus, in the conventional pylon  500 , redundancy is ensured by connecting the pylon strut  110  to the wing  100  by the pin joint at the attachment point  111  and the two links (first and second links). 
     Though  FIG. 4  shows that the wing  100  is directly connected to the first link  113  or the like for the sake of clarity, such connections are normally made with fittings. 
     SUMMARY OF THE INVENTION 
     As described above, the pylon strut  110  is supported on the wing  100  in cantilever fashion, and is constrained to the wing by the pin joint at the attachment point  111  and the first link  113 . That is, there is a case where the second link  115  is hardly mounted to the wing  100  because the second link  115  makes no contribution to constrain the pylon strut  110 , and assembly tolerances are accumulated at the attachment point  115   b  (or  115   a ) for the second link  115 , which point is more distant than the attachment point  111 , which is a reference point. In such a case, forces are exerted on the pylon strut  110  so as to intentionally cause elastic deformation (hereinafter referred to as “preload”), so that the positional displacement caused due to the accumulated assembly tolerances is absorbed. 
     The load exerted on the pylon strut  110  as a preload is determined based on the rigidity and size of the pylon strut  110 . However, the excessively larger load may be caused when preloaded. In such a case, a tool required for the preload operation is expensive one having a high rigidity, and the preload operation requires higher levels of exertion. 
     The present invention was made in view of such a problem, and has an object to provide an aircraft pylon capable of being mounted to a wing without exertion of preload while ensuring that redundancy is provided in the pylon. 
     In the present invention, the attachment between the pylon strut and the wing is restricted to a single link other than the attachment reference point. However, in this case, the necessary redundancy is not provided unless any other measure is taken. Thus, the present invention proposes that redundancy is provided in a linked attachment structure. 
     That is, an aircraft pylon of the present invention includes: a pylon strut for supporting an engine of an aircraft; a pin joint mechanism for connecting the pylon strut to a main wing of the aircraft; a link member disposed between the pylon strut and the main wing of the aircraft, wherein the link member includes a collection of plural independent link elements. 
     In the present invention, the position of the pin joint mechanism may be a reference position to which the pylon strut is mounted. 
     As used in the present invention, the expression “independent” refers to being independent as a link element. Thus, the “plural independent link elements” of the present invention encompasses cases, for example, where two section steel members used as independent link elements are fastened together by a fastener (bolt and nut). 
     This means the link member of the present invention includes at least two embodiments. In the first embodiment, the plural link elements are not fastened together, and the respective link elements are separately disposed between the pylon strut and the main wing. In the second embodiment, the plural link elements are fastened together. 
     In the latter embodiment, since the plural link elements are fastened into one, the workload in disposing the link elements between the pylon strut and the wing is reduced compared with the case where the respective link elements are separately disposed therebetween. Moreover, even if one of the link elements is damaged and broken, it is free from the risk of falling off from the disposed position as it is fastened to other link elements. 
     Preferably, in the link member of the present invention, each link element is pin jointed at attachment points to the pylon strut and the main wing, respectively as this provides redundancy in attachment points. 
     In the pylon of the present invention, in connecting the pin joint mechanism and the link member to the main wing, respectively, the pin joint mechanism and the link member are desirably connected to a common fitting mounted on the main wing. This reduces the amount of accumulated assembly tolerances and the workload in mounting fittings on the wing. 
     In the pylon of the present invention, the link member is preferably provided above where the pin joint mechanism is connected to the main wing. 
     This configuration provides a broaden space at the rear of the pylon, thereby facilitating various operations such as assembling, maintenance, and the like. 
     According to the present invention, an aircraft including the above-described pylon is provided wherein the link member includes a collection of plural independent link elements. 
     In a pylon according to the present invention, the attachment between the pylon strut and the wing is restricted to a single link other than the attachment reference point, thereby resulting in the reduced accumulated tolerances compared to cases where two links are used. In addition, the use of a single link facilitates locating an attachment point close to the attachment reference point. Furthermore, in a pylon according to the present invention, the link member which includes a collection of plural independent link elements provides redundancy in the mounting structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a mounting structure between a pylon and a wing in accordance with an embodiment of the present invention; 
         FIG. 2  is a schematic diagram illustrating details of the mounting structure between the pylon and the wing in accordance with the embodiment of the present invention; 
         FIGS. 3A, 3B and 3C  are diagrams illustrating details of attachment points of the present embodiment; and 
         FIG. 4  is a schematic diagram illustrating a mounting structure between a pylon and a wing of the prior art. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a pylon in accordance with a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, “front” and “rear” are determined based on a flying direction of an aircraft. 
     As shown in  FIG. 1 , a pylon  50  of the present embodiment is provided on a wing  10  of an aircraft, supporting a turbofan type engine  20 . 
     The pylon  50  is configured to include a pylon strut  11 , a link member  15 , and a connecting fastener P 1 . The pylon strut  11  is provided at an undersurface of the wing  10  to extend toward a front X in a flying direction (see  FIG. 1 .). The shape of the pylon strut  11  in a section orthogonal to a longitudinal direction is trapezoidal and its sectional area gradually reduces toward the front side from the rear side. 
     The engine  20  includes a fan section  20   a  provided at the front X in the flying direction, and an engine core section  20   b  provided at the rear of the fan section  20   a . The fan section  20   a  is provided with a fan incorporated inside a shroud  21  circular in section. The engine core section  20   b  is accommodated in a housing  22  in a cylindrical shape with a diameter smaller than that of the fan section  20   a , and includes a mechanism for driving the fan. 
     In the engine  20 , the fan section  20   a  is mounted to the undersurface of the pylon strut  11  by a front engine mount  30 , and the engine core section  20   b  is mounted to the undersurface of the pylon strut  11  by a rear engine mount  40 . 
     The engine  20  and the pylon strut  11  are housed in a pylon fairing (not shown) and a nacelle  23 . 
     The front engine mount  30  includes a top surface  30   a  and an undersurface  30   b , which are fixed to the undersurface of the pylon strut  11  and the shroud  21  of the fan section  20   a  of the engine  20 , respectively, by connecting means such as bolts. 
     The rear engine mount  40  is formed of an engine side mount member  41  fixed to the engine  20  side, and a strut side mount member  42  fixed to the pylon strut  11  side. 
     Here, the engine side mount member  41  has an undersurface  41   a  fixed to the top surface of the housing  22  of the engine core section  20   b  of the engine  20  by connecting means such as bolts. 
     Furthermore, one end  45   a  of a reinforcing rod  45  is connected to an upper portion of the engine side mount member  41 . The reinforcing rod  45  has the other end  45   b  connected to the vicinity of a connecting portion of the engine core section  20   b  and the fan section  20   a  of the engine  20 . This allows the reinforcing rod  45  to reinforce support for the front side of the engine  20 . 
     The pylon strut  11  is pin jointed at an attachment point R 1 , which is a reference point, to the wing  10  by a connecting fastener P 1  (pin joint mechanism). The attachment points R 1  and the respective connecting fasteners P 1  may be provided at opposing ends in the width direction of the pylon strut  11 . The same applies to attachment points R 2  and R 3 . The pylon strut  11  is pin jointed at the attachment points R 2  and R 3 , respectively, to the wing  10  by the link members  15 . Accordingly, the pylon strut  11  is supported by the wing  10 . 
     More specific attachment structures are shown in  FIGS. 2, 3A, 3B and 3C . 
     As shown in  FIGS. 2 and 3A , at the attachment point R 1 , a connecting piece  11   a  of the pylon strut  11  side is pin jointed to a connecting piece  18   a  of a fitting  18  side of the wing  10  by the connecting fastener P 1 . 
     As shown in  FIGS. 2, 3B, and 3C , at the attachment point R 2 , a connecting piece  11   b  of the pylon strut  11  side is joined to a connecting piece  15   c  of the link member  15  by the fastener P 2 . 
     As shown in  FIGS. 3B and 3C , the link member  15  includes two channel steels  15   a  and  15   b ; and connecting pieces  15   c  provided at ends of the channel steels  15   a  and  15   b , respectively. The two channel steels  15   a  and  15   b  are attached back-to-back at their webs and secured together with a fastener  16  such as bolt and nut or the like. The connecting piece  15   c  defines two recesses  15   c   1  and  15   c   2 . 
     Also, the connecting piece  11   b  is provided with two connecting projections  11   b   1  and  11   b   2 . These connecting projections  11   b   1  and  11   b   2  are arranged in the recesses  15   c   1  and  15   c   2 , respectively, so that the connecting piece  11   b  is connected by the connecting fastener P 2  to the corresponding connecting piece  15   c  in an interdigitated state. The respective fasteners P 2  may be provided for the channel steels  15   a  and  15   b , each fastener for a corresponding link element. 
     Alternatively, the connecting piece  11   b  defines the recesses while the link member  15  is provided with connecting projections. 
     An attachment structure between the fitting  18  and the link member  15  at the attachment point R 3  is generally similar to the connecting structure between the pylon strut  11  and the link member  15  as described above, that is, a connecting piece  18   b  of the fitting  18  is pin jointed to the link member  15  by a fastener P 3 . 
     In the present embodiment, the three attachment points R 1 , R 2 , and R 3  are provided, and the attachment points R 2  and R 3  associated with the link member  15  are closed to the attachment point R 1  in the attachment. In the conventional mounting structure as shown in  FIG. 4 , the attachment point  111  as a reference point (corresponding to the attachment point R 1 ) and the attachment points  115   a  and  115   b  are provided, and particularly the attachment point  115   b  is far from the attachment point  111 . Therefore, in the present embodiment, the amount of accumulated tolerances is reduced compared to the conventional mounting structure of  FIG. 4 , thereby eliminating the need to exert any preload when attaching the pylon strut  11 . In the present embodiment, the fitting  18  has two attachment positions, i.e., the attachment points R 1  and R 3  (corresponding to the attachment points  111  and  113   b , respectively, in the conventional structure), which clearly indicates the fact that the attachment points R 2  and R 3  are close to the attachment point R 1 . 
     The structure of the present embodiment eliminates the need of the second link  115  of the conventional structure as shown in  FIG. 4  and a fitting disposed between the second link  115  and the wing  100 , thereby reducing the weight of an aircraft and decreasing parts count which leads to a reduction of production costs. In addition to the elimination of these parts, the attachment point R 3  is provided higher than the attachment point R 1  and the link member  15  is disposed above the connecting piece  11   a , thereby providing a new space and improving rigging allowances for loading rigs in the fairing at the rear portion of the pylon  50  or the like. 
     The structure of the link member  15  ensures the redundancy in the mounting structure between the pylon strut  11  and the wing  10 . 
     That is, as the link member  15  includes two link elements (channel steels  15   a  and  15   b ), even if one of the link elements is damaged, the other undamaged link element maintains the state of the attachment between the pylon strut  11  and the wing  10 . Though an H-section steel can be used to form a link member similar to the link member  15 , the use of an H-section steel as a one-piece member does not ensure redundancy. In addition, the two link elements are joined to the pylon strut  11  by the respective independent connecting fasteners P 2  ( FIG. 3B ). Thus, even if one of the fasteners is damaged, the other undamaged fastener maintains the state of the attachment between the pylon strut  11  and the wing  10 . 
     The mounting structure of the present embodiment adopts a fail-safe design structure, and thus ensures redundancy without the second link  115  used in the conventional structure, as described above. 
     The present invention has been described in the embodiments thereof, but is not limited to the above embodiments. 
     For example, the link member  15  is constituted by channel steels  15   a  and  15   b  fastened together, but they may be separately disposed between the pylon strut  11  and the wing  10  without being fastened together. However, the use of channel steels fastened into one in such a manner as the link member  15  of the present embodiment results in a reduced workload in disposing the link member between the pylon strut  11  and the wing  10 . For example, in the case of the link member  15  in an integrated form, through-holes for insertion of connecting fastener P 2  can be simultaneously formed in the channel steels  15   a  and  15   b  without any registration error of the through-holes which would be caused in the case of individually forming respective through-holes in the channel steels  15   a  and  15   b , thereby reducing the amount of accumulated assembly tolerances. Moreover, even if one channel steel,  15   a , is damaged and broken, it is free from the risk of falling off from the disposed position as it is fastened to the other channel steel  15   b.    
     Although, in the above-described embodiments, the pin joint at the attachment point R 1  and the pin joint to the wing  10  side by the link member  15  are connected to the common fitting  18  mounted on the wing, the present invention allows for connection made to respective separate fittings. However, the connection to the common fitting is preferable as it reduces the amount of accumulated tolerances and the workload in mounting fittings on the wing. 
     Although, in the above embodiment, an example is shown in which a link member is constituted by channel steels, members for constituting the link member are not only channel steels, but also other shaped members such as H-section steel and angle steels to be combined to form a link member. The link member is formed of materials other than steel, such as carbon fiber composite material. 
     Other than this, the configurations cited in the above described embodiments can be selected or omitted, or can be arbitrarily changed to the other configurations, without departing from the gist of the present invention.