Abstract:
In aircraft cargo decks are provided to receive loads stored in the cargo compartment ( 9 ). The aircraft comprises an outer skin ( 12 ) to which ribs ( 11 ) are attached. To simplify the construction and the assembly it is proposed that the cargo deck be composed of a plurality of floor modules ( 20 ), which are fixed within the cargo compartment ( 9 ) and form the cargo deck. To the ribs ( 11 ) are attached longitudinal beams ( 35 ), on which the floor modules ( 20 ) can be mounted.

Description:
RELATED U.S. APPLICATIONS  
       [0001]     Not applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable.  
       REFERENCE TO MICROFICHE APPENDIX  
       [0003]     Not applicable.  
       FIELD OF THE INVENTION  
       [0004]     The invention relates to a cargo deck according to the precharacterizing clause of claim  1  as well as to a method of assembling such a cargo deck.  
       BACKGROUND OF THE INVENTION  
       [0005]     From the document DE AS 21 62 042 a cargo deck of this kind is known, in which in the region of a loading-space door a first section of the cargo deck is formed by a plurality of ball mats, PDUs and similar functional units. Adjacent to this entrance region are a plurality of floor panels, between or on which are disposed roller conveyors, latches and additional PDUs, so that items of freight such as containers can be transported in through the cargo-compartment door and then onward, in the long direction of the aircraft, to their final storage position. Once in the storage positions, the containers are anchored by means of latches.  
         [0006]     In the conventionally constructed cargo decks transverse beams are initially installed in the fuselage of the aircraft, on which are subsequently mounted profile elements to receive the latches, PDUs or transport rollers, with floor panels or ball mats situated between them. In the region of the cargo-compartment door the construction is still more elaborate. Here a kind of table is installed, on which the said functional units (PDUs, latches etc.) are disposed, and on which the ball mats are mounted (while leaving the PDUs etc. free). In every case, therefore, initially supporting structures are attached to the aircraft fuselage, on which the structures that form the cargo-compartment floor are subsequently mounted. The conventional construction of the cargo deck is thus complicated and furthermore results in a heavy weight.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     The invention is directed toward the objective of disclosing a cargo deck and a method for its assembly that ensures a reduction of complexity, regarding construction as well as manufacture and installation in the aircraft.  
         [0008]     This objective is achieved, in the case of a cargo deck to receive loads in the cargo compartment of an aircraft having an outer skin to which ribs can be attached, in that the cargo deck is made up of a plurality of floor modules that are fixed within the cargo compartment and constitute the cargo deck, and at the outer skin or the ribs longitudinal beams are attached on which the floor modules can be mounted.  
         [0009]     One essential idea of the invention is that it no longer involves the conventional structure in which the transverse beams are each individually attached to the aircraft fuselage and then the elements that form the cargo-compartment floor are mounted on them. Instead, modules are constructed that comprise sections of the cargo deck including the associated supporting structures (transverse beams), and these modules are then attached as a whole to the longitudinal beams. The result is not only a considerably simplified construction of the cargo deck, because the modules can be (pre-)assembled outside the fuselage of the aircraft; in addition, a considerable simplification is achieved because the modules are not attached directly to the outer skin or the ribs, but rather to the longitudinal beams. That is, whereas during manufacture of the aircraft fuselage there is a degree of tolerance regarding the distances by which the ribs are separated, the longitudinal beams can be finished outside the fuselage and hence with a high degree of precision. This means that the corresponding fixation devices for fixing the modules to the longitudinal beams can be attached accurately, so that when the modules are installed in the aircraft fuselage the entire arrangement can be fitted precisely into position.  
         [0010]     Preferably the longitudinal beams consist of a material having a thermal expansion coefficient that corresponds substantially to that of the outer skin. This is especially important when the outer skin of the aircraft consists of a composite material, e.g. carbon-fiber-reinforced plastic, a material that is extremely light. On the other hand, this material is only relatively poorly suitable for construction of a cargo-compartment floor, because it is relatively sensitive to impacts in locally restricted regions. Therefore the cargo-compartment floor is preferably made of light metal, in particular of aluminum components. The modules can now in turn be fixed to the longitudinal beams in such a way that changes in length of the longitudinal beams relative to the modules are accommodated (e.g., owing to corresponding tolerances of the fixation elements) . When vertical loads are imposed, such tolerances play no role. To receive loads imposed in the long direction of the aircraft, each of the modules is connected to the outer skin at only two points, which are situated on opposite sides of the cargo compartment.  
         [0011]     The longitudinal beams and/or the ribs are preferably provided with bores, rapid-closure elements or similar fixation devices for attachment of the floor modules, so that this simple method of attachment can be used.  
         [0012]     The floor modules are attached to the longitudinal beams in such a way that substantially no forces acting in the longitudinal direction of the aircraft can be introduced from the floor modules into the longitudinal beam.  
         [0013]     Preferably a single pair of longitudinal beams is provided for connection to the floor modules, i.e. one longitudinal beam on each side of the cargo compartment.  
         [0014]     At the floor modules transverse beams are preferably provided, with which to attach the floor modules to the longitudinal beams, so that exactly specifiable fixation points are present. The floor modules or their transverse beams comprise supporting feet for attachment to the ribs. In general two such supporting feet suffice to achieve sufficient stability, but of course it is also possible to use larger numbers of supporting feet. For fixation of the supporting feet to the ribs, the above-mentioned manufacturing tolerances do not play any important role, because the supporting feet can be made elastic in the direction of the aircraft long axis, so that manufacturing differences can easily be compensated. That is, the supporting feet are almost exclusively needed to receive vertical loads, whereas forces in all other directions are transmitted into the outer skin by way of the longitudinal beams and hence the above-mentioned fixation points.  
         [0015]     Preferably the ribs for fixation of the modules and/or the longitudinal beams comprise fixation elements that are attached to the ribs either in a zone between the outer skin and an edge region of the rib or else to the edge region itself, in which case no drilling is needed. This measure ensures that the ribs retain their function of stiffening the outer skin, despite the fact that the modules or longitudinal beams are mounted on them.  
         [0016]     Preferably the modules are decoupled from one another with reference to forces in the long direction of the aircraft. This achieves a further improvement with regard to the compensation of thermally induced length changes, as well as an increase in assembly tolerance.  
         [0017]     Furthermore, the above-mentioned objective is achieved by a method of assembling a cargo deck consisting of floor modules within an aircraft that is constructed from multiple barrel-shaped fuselage sections of an external skin reinforced by ribs, said method comprising at least the following steps:  
         [0018]     a) production of floor modules;  
         [0019]     b) production of longitudinal beams, including the provision of bores, rapid-closure elements or similar fixation devices for attaching the floor modules to the longitudinal beams;  
         [0020]     c) fixation of sections of the longitudinal beams within the fuselage sections;  
         [0021]     d) insertion of the floor modules into the fuselage section, and attaching them to the longitudinal beams.  
         [0022]     Hence an important idea underlying the method so designed resides in the fact that on one hand the floor modules can be manufactured outside the aircraft fuselage, while on the other hand it is extremely simple to install the floor modules, because of the (lightweight) longitudinal beams, which can likewise be produced outside the aircraft fuselage and make installation of the floor modules very easy. Fixation of the longitudinal beams within the aircraft fuselage is in turn very uncomplicated, likewise because of their low weight and simple construction.  
         [0023]     Preferably the longitudinal beams have a length no greater than that of the fuselage modules. As a result, the fuselage modules can be constructed so as to be substantially completely separate from one another, and need not be connected to one another until a final step of assembly has been reached. The transport of such fuselage sections (called “barrels” in technical jargon) can be done at various sites, as is customary in particular when several firms are collaborating on such a major project.  
         [0024]     Preferably the step d) above is followed by another step e) in which feet on the transverse beam of the floor module are attached to the ribs. This fixation is relatively simple, because the floor modules are already at substantially the correct place (or have even been attached to the longitudinal beams) and hence at least a vertical positioning has already been correctly carried out.  
         [0025]     Preferably after the step e), i.e. after the modules have been fixed in position within the fuselage, lining elements for the walls and ceiling are pushed into the fuselage sections and attached there. During this process the wall and ceiling lining elements have preferably been connected to one another, so that a separate fixation of these two elements with respect to one another during the final installation can be eliminated.  
         [0026]     The floor modules can not only be installed in the fuselage sections while these are still separate from one another, but rather it is possible and even necessary, if fuselage sections of a particular length have been selected, to install at least some of the floor modules after the fuselage sections have been put together. In this case the modules and where appropriate also the wall and ceiling linings have preferably been dimensioned such that they can be loaded into the aircraft through the cargo-compartment door, transported to the appropriate destination site and then attached there.  
         [0027]     Preferably while the floor modules are still outside the aircraft, i.e. prior to the step d), they are provided with sections of conductors for fluids and/or electrical current, or channels through which conductors or similar installation devices can be passed; after the step d) these are connected to one another. Here, again, it is easy to understand that pre-assembly outside the aircraft considerably facilitates the work of final installation.  
         [0028]     Preferably at least parts of floor panels, ball mats or similar deck sections of the modules are fixed to the modules after the step e). This makes it possible to keep the bilge space (below the cargo deck) free for any other mounting procedures that may be undertaken.  
         [0029]     In the following the invention is explained in greater detail with reference to drawings, wherein 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0030]      FIG. 1  is a perspective view of a fuselage section of an aircraft,  
         [0031]      FIG. 2  is a perspective view of a cargo-loading compartment with deck sections partially installed,  
         [0032]      FIGS. 3 and 4  are perspective views showing the mounting of profile elements on transverse beams,  
         [0033]      FIG. 5  is a perspective view of a floor module from above,  
         [0034]      FIG. 6  shows the floor module according to  FIG. 5  in perspective from below,  
         [0035]      FIG. 7  is a sectional representation in perspective of the mounting of a transverse beam in the aircraft,  
         [0036]      FIGS. 8 and 9  are perspective drawings of profile elements and intermediate elements, viewed from different directions,  
         [0037]      FIG. 10  shows the arrangement according to  FIGS. 8 and 9  in a partial section viewed from the front,  
         [0038]      FIGS. 11-13  are views, corresponding to those in  FIGS. 8-10 , of a second embodiment of intermediate elements,  
         [0039]      FIG. 14  shows two fuselage sections separated from one another, with a floor module that is to be installed and a wall/ceiling lining module,  
         [0040]      FIGS. 15-20  are additional drawings, like that in  FIG. 14 , to explain further installation steps,  
         [0041]      FIG. 21  is a perspective drawing to explain the fixation of the transverse beams to the outer skin,  
         [0042]      FIG. 22  is a perspective drawing like that in  FIG. 21 , but viewed from another angle,  
         [0043]      FIG. 23  is a front view of the embodiment according to  FIGS. 21 and 22 ,  
         [0044]      FIG. 24  is a detail view of the section XXIV in  FIG. 23 ,  
         [0045]      FIG. 25  is a detail view of the section XXV in  FIG. 23 ,  
         [0046]      FIG. 26  is a detail view in perspective of the section XXVI in  FIG. 22 ,  
         [0047]      FIG. 27  is a detail view of the section XXVII in  FIG. 22 ,  
         [0048]      FIGS. 28-34  are drawings corresponding to those in  FIGS. 21-27 , but of another embodiment of the invention, and  
         [0049]      FIGS. 35-41  are drawings corresponding to those in  FIGS. 21-27  and  28 - 34 , but of another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0050]     In the following description, the same reference numerals are used for identical parts or parts with identical actions.  
         [0051]     As shown in  FIG. 1 , an aircraft fuselage  10  is subdivided (as is known) into an upper section  8  to be used as passenger compartment and a lower section to form a cargo compartment  9 . The aircraft fuselage  10  is formed by an outer skin  12  that is reinforced by attaching ribs  11  to its inner surface. The outer skin and the ribs can be made of light metal or of a composite material.  
         [0052]     Within the cargo compartment  9  are mounted deck sections  20  that together constitute a cargo deck. In the bilge space (below the deck sections  20 ) are disposed installation channels  13 , conductors etc., which serve to supply both the passenger compartment and the cargo compartment with fluids (air, water, waste water, etc.) or electricity (as a source of energy, for data transmission, etc.).  
         [0053]     As can be seen in  FIG. 2 , the deck sections  20  are made on one hand of flat elements such as floor panels  22  or ball mats  21 , which are connected to one another by way of profile elements  23  oriented parallel to the long axis of the aircraft. These flat elements  21 ,  22  are preferably screwed or riveted to the profile elements  23 , so as to produce a rigid structure extending over the entire width of the deck section  20 . In the profile elements are fastened a plurality of functional units, e.g. PDUs  42  (roller drive units), transport rollers  43  or latches  44 . In the region of a cargo-compartment door, and hence in the region of the ball mats  21 , are additionally attached ball elements  40 , guide elements  41  and a plurality of other PDUs  42  and latches  44 , as is known per se.  
         [0054]     For stiffening the deck sections  20  and transmitting vertically imposed loads, transverse beams  30  are provided below the flat elements  21 ,  22  and profile elements  23 ; these beams comprise feet  31 ,  32  and, at their outer edges, bearing surfaces  33 . The feet  31 ,  32  of the transverse beams  30  are fixed to ribs  11 , whereas the bearing surfaces  33  are seated on longitudinal profiles  35  that are attached to the ribs  11  along an outer zone of the aircraft fuselage. In addition, the transverse beams  30  comprise peripheral collars  34 , to which are attached other guide elements for containers that will be received.  
         [0055]     After the deck sections  20  have been installed in the loading space they are connected to one another by means of the profile elements  23 , as shown in  FIGS. 3 and 4 . Connection elements  24  provided for this purpose have the form of slots, so that two deck sections  20  that have been coupled together can be shifted with respect to one another, by a certain amount, in the direction of the long axis of the aircraft.  
         [0056]     The deck sections  20  shown in  FIGS. 5 and 6  form compact modules that consist on one hand of the flat sections  21  and/or  22 , connected together by the profile elements  23 , and on the other hand of the transverse beams  30 . Furthermore, these modules can be provided in certain sections with the installation channels  13  as well as drainage conduits  16  (to remove water from the cargo deck) or with electrical leads, which can be connected to one another by way of connector sockets  15  between the modules.  
         [0057]     The modular deck sections thus constructed are endowed with a stiffness with respect to shear forces, owing to the rigid connection between the flat sections  21 ,  22  and the profile elements  23 , such that longitudinal forces, introduced for instance by way of latches  44  in the middle of a deck section (see  FIG. 5 ), are transmitted outward, in the direction toward edge profiles  25  or the profile elements  23  disposed near the latter. From there these longitudinal forces—as is described below—are transmitted to the skin of the aircraft.  
         [0058]      FIG. 7  shows how the transverse beams  30  are connected to the ribs  11  and/or longitudinal profiles  35  as the deck sections or modules are being installed in the cargo space. For this purpose, firstly there are provided, on the ribs  11  and longitudinal profiles  35 , fixation elements  36  such as are known and have been well tested for use in the fixation of aircraft seats. Secondly, corresponding counter-fixation elements  36 ′ are provided on the feet  31  and/or the bearing surfaces  33  of the transverse beams  30 . This means that during installation of a deck section or module in the cargo compartment, the module need merely be lifted into the cargo compartment and fixed in place there by means of the fixation elements  36 ,  36 ′. Fixation of the transverse beams  30  to the longitudinal profiles  35  can be done from above, while for fixation of the feet  31  to the ribs  11  either access openings  26  (see  FIG. 5 ) are provided in the floor panels  22  or the ball mats  21 , or else at the important sites these elements are not yet fixedly attached to the profile elements during installation.  
         [0059]     To transmit the longitudinal forces from the deck sections  20  to the outer skin  12  of the aircraft fuselage  10  intermediate elements  50  are provided, which in the following will be described in detail with reference to  FIGS. 8-10 . Furthermore, these intermediate elements  50  comprise on one hand an outer coupling piece  51 , e.g. a band-shaped region, that is rigidly fixed to the outer skin  12  between two ribs  11 , for instance by adhesive or rivets. In addition the intermediate element  50  comprises an inner coupling piece  52 , which is connected to the peripheral profile  23  of a deck section  20  so that it cannot be pulled loose (in the direction of the aircraft long axis). The connecting piece  53  disposed between the inner coupling piece  52  and the outer coupling piece  51  is in turn stiff with respect to shear forces but relatively yielding with respect to bending forces, so that forces in the direction of the profile elements  23 , i.e. in the long direction of the aircraft fuselage  10 , are transferred from the profile elements  23  through the intermediate elements  50  to the outer skin  12 , whereas forces perpendicular thereto, i.e. those acting downward and outward, are transferred only very slightly to the outer skin  12 . Mounting of the intermediate elements  50  can be carried out especially simply when the elements comprise outer lobes  54  by way of which the intermediate elements  50  are fixed to the ribs  11 .  
         [0060]     The intermediate elements  50  are very short in relation to the overall length (in the aircraft long direction) of the deck sections  20 , and in the example shown here they are provided at only one end of each outer profile element  23  of a deck section  20 . This ensures that when the materials used for outer skin  12  and deck sections  20  are extended to different degrees, for instance owing to temperature differences, and have different coefficients of expansion, no tensions can arise between the outer skin and the deck sections  20 . That is, in the long direction of the aircraft one end of each deck section  20  is fixed to the aircraft fuselage  10 , whereas its other end is seated so as to be floating in the aircraft long direction. Only forces directed perpendicular to the long axis of the aircraft are transmitted over the entire length of the deck sections  20  in the aircraft fuselage  10 .  
         [0061]     The embodiment of the invention shown in  FIGS. 11-13  differs from the one in  FIGS. 8-10  in that the intermediate elements  50  are coupled to the longitudinal profiles  35  on which are seated the deck sections  20  by way of the bearing surfaces  33  of their transverse beams  30 , on which in turn the profile elements  23  are mounted. With this arrangement, therefore, the longitudinal forces are transmitted into the intermediate elements  50  not directly but rather by way of end sections of the transverse beams  30  and sections of the longitudinal profiles  35 , and thus transmitted to the outer skin  12 . With respect to function, however, there is no difference between this arrangement and the embodiment according to  FIGS. 8-10 , because also in this embodiment the transmission of longitudinal forces applied over the entire width of the deck sections  20  is initially outward into the outermost profile elements  23  situated there, followed by (substantially punctate) transfer to the intermediate elements  50  and on to the outer skin  12 . Here again, therefore, the transverse beams  30  are not directly involved in the transmission of the longitudinal forces and hence can be constructed so that they are yielding or weak with respect to such forces.  
         [0062]     In the following, the mounting is described in greater detail with reference to  FIGS. 14-20 .  
         [0063]     As shown in  FIG. 14 , the aircraft is composed of several fuselage sections, only two of which are illustrated here. The front fuselage section  1  in  FIG. 14  contains the cargo-compartment door  14 , and the second fuselage section  1  is immediately adjacent to the back of the first section. The deck section shown in  FIG. 14  is installed in these fuselage sections, as is the wall/ceiling lining section  27 .  
         [0064]      FIG. 15  shows the first fuselage section  1 , into which a deck section  20 , i.e. a corresponding module with floor panels  22 , has just been inserted. For clarification, a module  20  with ball mats  21  is shown separately. In addition, the figure shows a wall/ceiling lining element  27  (like that in  FIG. 14 ), which is mounted apart from the cargo-compartment door  14  and which comprises two side walls, whereas the wall/ceiling lining element  27 ′ in  FIG. 15  is intended for installation in the door region.  
         [0065]      FIG. 16  shows how a module  20  is pushed into the fuselage section  2 , and there is set onto the edge profile  25  and attached thereto (as shown in more detail in  FIG. 7 ) by means of the fixation elements  36 ,  36 ′. The feet  31  of the transverse beam  30  are attached to the ribs  11 . After this attachment has been completed, the wall/ceiling lining element  27  is pushed into the fuselage section  2  and is likewise fixed in position.  
         [0066]     This installation, and of course also a dismantling for the purpose of exchange as well as subsequent installation of the wall/ceiling lining element, can be done through the cargo-compartment door  14 .  
         [0067]     This clearly also applies to the deck sections or modules, as shown in  FIG. 18 . In particular, for this purpose—as shown in  FIG. 19 —at a time when the fuselage sections  1  and  2  shown here have already been connected to one another, initially a module  20  with ball mats  21  is installed in the region of the cargo-compartment door  14 , after which an adjacent module (as shown in  FIG. 18 ) is loaded in through the cargo-compartment door  14  and—as shown in  FIG. 19 —pushed over the already installed module  20  and finally—as shown in  FIG. 20 —is fixed in its designated position within the cargo compartment.  
         [0068]     In the following another way to attach the transverse beam  30  or longitudinal profile  35  to the outer skin is explained. At this juncture it should be emphasized that the outer skin concerned in the present description and shown in the drawings can also be “compact”, e.g. constructed in sandwich form, so that the ribs  11  or other (customary) longitudinal elements for stiffening the outer skin  12  as shown in the drawings are no longer visible at least from outside the skin (if they are even present as structures at all), because the present procedure produces an outer skin that is smooth even on its inner surface.  
         [0069]     The embodiment shown in FIGS.  21  to  27  is distinguished by the fact that the longitudinal profiles  35  or sections thereof, which thus serve as intermediate elements  50 , each traverse a longitudinal stiffening element  37  before being connected to the outer skin  12 . Here, again, the longitudinal beams  35  if suitably shaped can span the entire length of the aircraft, or can also be constructed as short sections (as shown in the drawings).  
         [0070]     The embodiment of the invention shown in  FIGS. 28-34  is distinguished by the fact that the longitudinal profile  35  is constructed as a “shoe”, which is attached directly to the transverse beam  30  or is formed integrally therewith. This “shoe” is fixed to the longitudinal stiffening element  37  by way of fixation elements  36 , as is particularly evident in  FIGS. 31-34 . As shown in the figures, this also applies to the feet  32  of the transverse beam  30 .  
         [0071]     In the embodiment of the invention shown in  FIGS. 35-41  the longitudinal profiles  35  are as a whole constructed so as to traverse two longitudinal stiffening elements  32 . In this case the longitudinal profiles  35  can either pass over the entire length of the aircraft interior or be only short sections (as can be seen in  FIGS. 35 and 36 ), constructed as short, shoe shaped sections. They then represent, so to speak, intermediate elements  50  through which longitudinal forces are transmitted directly to the outer skin  12 .  
         [0072]     At this juncture it should once again be emphasized that a substantial point resides in the fact that the longitudinal forces are introduced over the entire floor regions and (as determined statically) are transferred to the outer skin at end corners of the floor modules and/or at ends of the transverse beams.  
       LIST OF REFERENCE NUMERALS  
       [0000]    
       
           1  First fuselage section  
           2  Second fuselage section  
           8  Upper section  
           9  Cargo compartment  
           10  Aircraft fuselage  
           11  Ribs  
           12  Outer skin  
           13  Connection channel  
           14  Cargo-compartment door  
           15  Installation socket  
           16  Drainage conduit  
           20  Deck section  
           21  Ball mat  
           22  Floor panel  
           23  Roller conveyor/profile element  
           24  Connection element  
           25  Edge profile  
           26  Access opening  
           27  Wall/ceiling lining  
           30  Transverse beam  
           31  Foot  
           32  Foot  
           33  Bearing surface  
           34  Collar  
           35  Longitudinal profile  
           36 , 36 ′ Fixation element  
           37  Longitudinal stiffening element  
           40  Ball element  
           41  Guide element  
           42  PDU  
           43  Roller  
           44  Latches  
           50  Intermediate element  
           51  Outer coupling piece  
           52  Inner coupling piece  
           53  Connecting piece  
           54  Outer lobe