Patent Publication Number: US-2023148389-A1

Title: Structural assembly for an aircraft

Description:
TECHNICAL FIELD 
     The disclosure herein relates to the field of aircraft, in particular to a structural assembly of an aircraft. The disclosure herein thus relates to an aircraft having such a structural assembly. 
     BACKGROUND 
     An aircraft conventionally has a fuselage that exhibits a structure to which is fixed a skin ensuring, among other things, the sealing of the cabin accommodated in the fuselage with respect to the outside. 
     The aircraft likewise has landing gears which can be retracted into the fuselage once the aircraft is in flight. In order to accommodate a landing gear, the aircraft has a compartment which is delimited or defined inside the fuselage and which has walls forming a sealed barrier. This compartment has an opening to the outside to allow the landing gear to pass through and a door which is closed to shut off the opening once the landing gear is retracted. 
       FIG.  4    shows a section through an aircraft  400  of the prior art in a plane perpendicular to the longitudinal direction X of the aircraft  400 .  FIG.  4    shows a structural assembly  402  which, in this instance, has a plurality of main gantries  404   a - b  distributed and fixed together in the longitudinal direction of the structural assembly  402  and two transverse panels (which are not shown) at the front and the rear of the main gantries  404   a - b  that together delimit or define the compartment  50  for the landing gear. The main gantries  404   a - b  are incorporated in the structure  404  of the aircraft  400  to which the skin is fixed. Each main gantry  404   a - b  takes the form of an arch. 
     The structural assembly  402  likewise has pairs of secondary gantries  408   a - b  which extend parallel to the longitudinal direction X between the main gantries  404   a - b  and which are fixed by their ends to the transverse panels. 
     A plurality of transverse walls  410  is fixed between each pair of secondary gantries  408   a - b . The transverse walls  410  are distributed in the longitudinal direction X. 
     Linings  412  are fixed between the main gantries  404   a - b  and the transverse panels. These linings  412  constitute the threshold of the compartment  50  and they form a sealed barrier between the compartment  50  and the rest of the aircraft  400 . The linings  412  extend beneath the secondary gantries  408   a - b  and the transverse walls  410  and they are fixed at the bottom part of the secondary gantries  408   a - b.    
     Over the width of the aircraft  400 , the structural assembly  402  likewise has a plurality of crossmembers  406 , in this instance three crossmembers, which extend transversely with respect to the longitudinal direction X, that is to say parallel to the transverse panels. A plurality of these three crossmembers  406  is distributed in the longitudinal direction X. 
     A floor  414  and the rails for fixing passenger seats are fixed to these crossmembers  406 . The floor  414  is likewise fixed to the main gantries  404   a - b.    
     The crossmembers  406  are disposed above the secondary gantries  408   a - b  and each crossmember  406  is disposed in a straddling manner between two secondary gantries  408   a - b  of different pairs or between a secondary gantry  408   a - b  and a main gantry  404   a - b.    
     Each crossmember  406  is connected to the two secondary gantries  408   a - b  or to the secondary gantry  408   a - b  and to the main gantry  404   a - b  via two connecting rods  416  and each connecting rod  416  is mounted so as to be able to freely rotate, via a first end, on a lower part of the crossmember  406  and, via its second end, on an upper part of the secondary gantry  408   a - b  or of the main gantry  404   a - b.    
     Each rotation is performed about an axis of rotation transverse with respect to the longitudinal direction X. 
     Although such an arrangement is entirely satisfactory, it is necessary to find an arrangement that makes it possible to gain space, in particular vertically, by reducing the distance between the floor  414  and the linings  412 . 
     SUMMARY 
     An object of the disclosure herein is a structural assembly of an aircraft, in particular in a compartment for a landing gear, which has a reduced height. 
     To that end, a structural assembly for an aircraft is disclosed having a longitudinal direction and a median plane, the structural assembly having:
         a plurality of pairs of main gantries, wherein, for a pair, the main gantries face one another with respect to the median plane and wherein the pairs are distributed in the longitudinal direction,   two transverse panels that are perpendicular to the longitudinal direction and are fixed at the front and the rear of the plurality of pairs of main gantries to together delimit a compartment for a landing gear of the aircraft,   at least one pair of secondary gantries which extend parallel to the longitudinal direction between the main gantries and the ends of which are fixed to the transverse panels,   at least one crossmember which extends parallel to the transverse panels and is disposed in a manner straddling at least one secondary gantry, and,   for each secondary gantry and each crossmember straddling the secondary gantry, a connecting rod mounted so as to be able to freely rotate, via a first end, on a lower part of the crossmember and, via a second end, on an outer lateral part of the secondary gantry.       

     Such an arrangement reduces the vertical bulk of the structural assembly. 
     According to an embodiment, each connecting rod extends vertically between the crossmember and the secondary gantry. 
     According to an embodiment, each connecting rod extends from the secondary gantry, rising towards the crossmember as it moves away from the secondary gantry. 
     Advantageously, between each pair of secondary gantries, the structural assembly has at least one transverse wall fixed between the secondary gantries of the pair, wherein the at least one transverse wall is inscribed in a plane perpendicular to the longitudinal direction; for the or each transverse wall, at least one crossmember is disposed above the transverse wall; and the structural assembly has two additional connecting rods mounted so as to be able to freely rotate, via a first end, on a lower part of the or a crossmember and, via their second end, on an upper lateral part of the transverse wall. 
     Advantageously, each additional connecting rod extends vertically between the crossmember and the transverse wall. 
     Advantageously, for each connecting rod, the rotation is performed about an axis of rotation parallel to the longitudinal direction. 
     The disclosure herein also proposes an aircraft having a landing gear and a structural assembly according to one of the preceding variants, wherein the landing gear retracts into the compartment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the disclosure herein mentioned above, along with others, will become more clearly apparent upon reading the following description of an exemplary embodiment, the description being given with reference to the appended drawings, in which: 
         FIG.  1    is a side view of an aircraft having a structural assembly according to the disclosure herein; 
         FIG.  2    is a sectional view of the fuselage of the aircraft of  FIG.  1    at a compartment for a landing gear according to the disclosure herein; 
         FIG.  3    is a perspective view of a structural assembly according to an embodiment of the disclosure herein; and 
         FIG.  4    is a sectional view of the fuselage of an aircraft of the prior art at a compartment for a landing gear. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows an aircraft  100  which has a fuselage  102 , on either side of which a wing  104  is fixed. At least one propulsion system  106  is fixed beneath each wing  104 . 
     By convention, the X direction is the longitudinal direction of the aircraft  100 , the Y direction is the transverse direction of the aircraft  100 , which is horizontal when the aircraft is on the ground, and the Z direction is the vertical direction or vertical height when the aircraft is on the ground, these three directions X, Y and Z being mutually orthogonal. 
     Moreover, the terms “front” and “rear” should be considered with respect to a direction of forward movement of the aircraft  100  during operation of the propulsion systems  106 , this direction being depicted schematically by the arrow F. 
     The aircraft  100  also has landing gears, in particular a main gear  108 , which retracts into a compartment  50  accommodated inside the fuselage  102 . As in the prior art, the compartment  50  has an opening to the outside to allow the landing gear  108  to pass through and a door which is closed to shut off the opening once the landing gear  108  is retracted. 
       FIG.  2    is a view similar to  FIG.  4    (which has already been explained) for a structural assembly  202  according to the disclosure herein. 
     The compartment  50  is delimited inside the fuselage  102  and has walls forming a sealed barrier. 
       FIG.  2    shows a section through the aircraft  100  according to the disclosure herein in a plane perpendicular to the longitudinal direction X.  FIG.  2    and  FIG.  3    show a structural assembly  202  which has the same longitudinal direction X and has a plurality of main gantries  204   a - b  distributed and fixed together in the longitudinal direction X of the structural assembly  202  and two transverse panels (which are not shown) that are fixed at the front and the rear of the plurality of main gantries  204   a - b  and together delimit the compartment  50  for the landing gear. The main gantries  204   a - b  are incorporated in the structure  204  of the aircraft  100  to which the skin is fixed and each main gantry  204   a - b  takes the form of an arch. The main gantries  204   a - b  are distributed in pairs over the length of the structural assembly  202  and, for a pair, the main gantries  204   a - b  face one another with respect to a median plane XZ of the aircraft  100 . 
     The main gantries  204   a - b  are distributed parallel to the longitudinal direction X and the transverse panels are perpendicular to the longitudinal direction X. 
     The structural assembly  202  likewise has at least one pair of secondary gantries  208   a - b  which extend parallel to the longitudinal direction X between the main gantries  204   a - b  and which are fixed by their ends to the transverse panels. 
     A plurality of transverse walls  210  is fixed between each pair of secondary gantries  208   a - b . The transverse walls  210  are distributed in the longitudinal direction X and each transverse wall  210  is inscribed in a plane perpendicular to the longitudinal direction X. The transverse walls  210  are fixed to the secondary gantries  208   a - b  by any suitable means, such as by welding, clamping screws, etc. 
     Depending on the width of the aircraft  100 , there may be multiple pairs of secondary gantries  208   a - b  juxtaposed in the transverse direction Y and, in the embodiment of the disclosure herein presented here, over this same width, there are then as many transverse walls  210  as pairs of secondary gantries  208   a - b  and the transverse walls  210  are aligned in this same transverse direction Y. 
     Linings  212  are fixed between the main gantries  204   a - b  and the transverse panels. These linings  212  constitute the threshold of the compartment  50  and they form a sealed barrier between the compartment  50  and the rest of the aircraft  100 . The linings  212  extend beneath the secondary gantries  208   a - b  and the transverse walls  210  and they are fixed at the bottom part of the secondary gantries  208   a - b.    
     Over the width of the aircraft  100 , the structural assembly  202  likewise has a crossmember  206  which extends transversely with respect to the longitudinal direction X, that is to say parallel to the transverse panels. A plurality of crossmembers  206  is distributed in the longitudinal direction X. 
     In the embodiment of the disclosure herein shown in  FIG.  2   , there is a single crossmember  206  over the width of the aircraft  100 , but there may be multiple crossmembers which are aligned over the width of the aircraft  100 , as in the case of the prior art. 
     In general, there is therefore at least one crossmember  206  which extends parallel to the transverse panels and is disposed in a manner straddling at least one secondary gantry  208   a - b , that is to say extending on either side of the secondary gantry  208   a - b . When there is a single crossmember  206 , the latter straddles all the secondary gantries  208   a - b.    
     A floor  214  and the rails for fixing passenger seats are fixed to these crossmembers  206 . The floor  214  is likewise fixed to the main gantries  204   a - b.    
     The crossmembers  206  are disposed above the secondary gantries  208   a - b  and the main gantries  204   a - b , and each crossmember  206  is disposed above the secondary gantries  208   a - b  and the main gantries  204   a - b.    
     Each crossmember  206  is also disposed above at least one transverse wall  210  and multiple transverse walls when they are aligned in the transverse direction Y. 
     Each crossmember  206  is connected to each secondary gantry  208   a - b  and to the longitudinal beams  404   a - b  by connecting rods  216   a - c.    
     Thus, for each crossmember  206 , the structural assembly  202  has two connecting rods of a first type  216   a , and each connecting rod of the first type  216   a  provides the connection between one of the main gantries  204   a - b  and the crossmember  206 . Each connecting rod of the first type  216   a  is mounted so as to be able to freely rotate, via a first end, on a lower part of the crossmember  206  and, via its second end, on an upper part of the main gantry  204   a - b . For each connecting rod of the first type  216   a , the rotation is performed about an axis of rotation transverse with respect to the longitudinal direction X. These connecting rods of the first type  216   a  take the overall form of the prior art connecting rods  416  associated with the same elements. The connecting rods of the first type  216   a  extend vertically between the crossmember  206  and the main gantry  204   a - b.    
     Thus, for each crossmember  206  and for each secondary gantry  208   a - b , the structural assembly  202  has a connecting rod of a second type  216   b  or of a third type  216   c  which provides the connection between the secondary gantry  208   a - b  and the crossmember  206 . Each connecting rod of the second type  216   b  and of the third type  216   c  is mounted so as to be able to freely rotate, via a first end, on a lower part of the crossmember  206  and, via its second end, on an outer lateral part of the secondary gantry  208   a - b . For each connecting rod of the second type  216   b  and of the third type  216   c , the rotation is performed about an axis of rotation parallel to the longitudinal direction X for easy mounting reasons. By contrast to the connecting rods  416  of the prior art, the connecting rods of the second type  216   b  and of the third type  216   c  are transversely offset and are not attached to the upper part of the longitudinal beams. The lateral offset makes it possible to gain space by moving the secondary gantries  208   a - b  closer to the crossmember  206 , and the vertical bulk of the structural assembly  202  is thus reduced, thereby reducing the distance between the floor  214  and the linings  212 . The outer lateral part of the secondary gantry  208   a - b  is the part that is on the other side of the secondary gantry  208   a - b  with respect to the transverse wall  210  which is between the secondary gantries  208   a - b . In the embodiment of the disclosure herein presented in  FIGS.  2  and  3   , each secondary gantry  208   a - b  has a lateral extension  219  on which the connecting rod of the second type  216   b  or of the third type  216   c  is mounted in a hinged manner and each lateral extension  219  is for example an added part fixed to the secondary gantry  208   a - b.    
     In general, for each secondary gantry  208   a - b  and each crossmember  206  straddling the secondary gantry  208   a - b , the structural assembly  202  has a connecting rod of a second type  216   b  or of a third type  216   c.    
     In a first embodiment of the disclosure herein, the connecting rods of the second type  216   b  extend vertically between the crossmember  206  and the secondary gantry  208   a - b.    
     In a second embodiment of the disclosure herein, the connecting rods of the third type  216   c  extend at an angle with respect to the vertical direction Z between the crossmember  206  and the secondary gantry  208   a - b . The connecting rod of the third type  216   c  thus advances from the secondary gantry  208   a - b , rising towards the crossmember  206  as it moves away from the secondary gantry  208   a - b.    
     In the second embodiment of the disclosure herein, for each transverse wall  210  and each crossmember  206 , the structural assembly  202  has two additional connecting rods  217  which provide the connection between each end of the transverse wall  210  and the crossmember  206 . The two additional connecting rods  217  are therefore also offset laterally with respect to the secondary gantry  208   a - b . Each additional connecting rod  217  is mounted so as to be able to freely rotate, via a first end, on a lower part of the crossmember  206  and, via its second end, on an upper lateral part of the transverse wall  210 . For each additional connecting rod  217 , the rotation is performed about an axis of rotation parallel to the longitudinal direction X. Each additional connecting rod  217  is thus on the other side of the secondary gantry  208   a - b  with respect to the connecting rod of the third type  216   c.    
     In general, between each pair of secondary gantries  208   a - b , the structural assembly  202  has at least one transverse wall  210  fixed between the secondary gantries  208   a - b  of the pair, wherein the at least one transverse wall  210  is inscribed in a plane perpendicular to the longitudinal direction X. For the or each transverse wall  210 , at least one crossmember  206  is disposed above the transverse wall  210 , and the structural assembly  202  has two additional connecting rods  217  mounted so as to be able to freely rotate, via a first end, on a lower part of the or a crossmember  206  and, via their second end, on an upper lateral part of the transverse wall  210 . 
     The additional connecting rods  217  extend vertically between the crossmember  206  and the transverse wall  210 . 
     While at least one example embodiment of the invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the example embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.