Abstract:
An energy absorber for aircraft, which includes one or more energy absorber elements and a housing, whereby the energy absorber elements can absorb crash impulses by plastic deformation within the housing. Thus, the load on the primary structure and the respective inboard devices is limited, which can lead to an increased, passive safety of the passengers and a weight reduction.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of German Patent Application No. 10 2006 007 030.5 filed Feb. 15, 2006, and of U.S. Provisional Application No. 60/773,423 filed Feb. 15, 2006, the disclosures of which are hereby incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to energy absorbers for aircraft. In particular, the present invention relates to an energy absorber for an aircraft, the use of such an energy absorber in an aircraft, and a method for energy absorption in an aircraft. 
       TECHNOLOGICAL BACKGROUND OF THE INVENTION 
       [0003]    In aircraft, holders or attachment elements for holding and attaching inboard devices, such as ceiling liners, overhead bins, or monuments, are used. In the case of rigid attachment elements, in particular in the event of intense accelerations, such as those that can occur in the event of severe turbulence or for example, also with an emergency landing, the resulting acceleration forces may be transmitted directly from the primary structure of the aircraft over the holder to the attached inboard device. Likewise, all forces or accelerations acting on the inboard device may be transferred directly via the holder or the holder system to the aircraft structure. 
         [0004]    Holders and the inboard devices attached thereto may be statically placed on the basis of static load or maximum service loads. A breakdown of the holder, such as for example, by breaking or bursting out from the inboard device based on excessive acceleration forces can occur, which may lead to damage to the holder, the inboard device, or the primary structure of the aircraft and further, may endanger or injure the passengers or lead to impairment with a possible evacuation. 
       SUMMARY OF THE INVENTION  
       [0005]    It may therefore be desirable to have an energy absorber for aircraft, which provides a secure attachment of inboard devices or other devices of the aircraft, also under intense mechanical loads. 
         [0006]    According to an exemplary embodiment of the present invention, an energy absorber for an aircraft is provided, the energy absorber comprising a first energy absorber element and a second energy absorber element, both for absorption of an acceleration energy or acceleration forces resulting therefrom by plastic deformation (or force limitation), and a housing, whereby the plastic deformation of the energy absorber element takes place within the housing and whereby the second energy absorber element is arranged parallel to the first energy absorber element and abuts flat on the first energy absorber element. 
         [0007]    By means of the energy absorber elements, which are integrated at least partially in the housing, the mechanical load on the inboard device, which is connected by the energy absorber with a primary structure of the aircraft, and which can be, for example, a luggage bin mounted over the passengers, may be limited. For example, the energy absorber may be designed for absorbing acceleration energy resulting from movement of the aircraft. By absorbing acceleration energies, the force transmissions from the primary structure of the aircraft to the inboard device or from the inboard device to the primary structure may be reduced. This may lead to an increased passive safety in the cabin. In addition, by using the energy absorber of the present invention with energy absorber elements, the construction of the inboard device may be designed in a material- or weight-savings manner, since the maximally occurring mechanical loads may be reduced. This may permit a weight-optimization of all components involved on the load curve (for example, inboard components, holder, and primary structure). In addition, with a statically overruled system, a uniform load distribution may be made possible, in particular with a structure deformed by load. 
         [0008]    By the use of multiple energy absorber elements, which are arranged parallel to one another and lie flat on one another (i. e. abut each other), the force levels may be increased. At the same time, the existing space may be better used and the differently positioned energy absorber elements (for example, in the form of sheets) affect a more favorable force distribution on the deck layers by the now existing two force lines. 
         [0009]    Thus, with the energy absorber of the present invention, crash impulses, like those that can occur with an emergency landing, may at least partially be absorbed. The resulting force impact accordingly may not be transferred completely to the inboard device, rather damped additionally or absorbed partially to a defined force level, so that malfunction may be prevented. 
         [0010]    By the principle of plastic deformation, it may further be possible to absorb multiple crash impulses, and in the forward as well as in the reverse direction. In other words, the energy absorber may work in two directions (specifically, are extracted from the housing and displaced into the housing) and thereby absorb impacts in different directions. 
         [0011]    According to a further embodiment of the present invention, the second energy absorber element is inlaid in the first energy absorber element. 
         [0012]    In this manner, it may be ensured that an absorbed force is distributed better on the housing. 
         [0013]    According to a further embodiment of the present invention, the energy absorber further includes a third energy absorber element and a fourth energy absorber element, whereby the third energy absorber element is inlaid in the fourth energy absorber element and whereby the third energy absorber element and the fourth energy absorber element are arranged adjacent to the first energy absorber element and second energy absorber element, so that both the energy absorber pairs are braced against one another with a rolling motion. The outwardly acting forces may be reduced, such that (with suitable construction) a separate housing may be eliminated and may be integrated in the geometry (for example, honeycomb plates with hatrack) to be held. 
         [0014]    Here, there may be no surfaces which are subject to friction. 
         [0015]    According to a further embodiment of the present invention, the housing includes a first cover plate or cover sheet, a second cover plate or cover sheet, and a fixed support for the second energy absorber element and the first energy absorber element. 
         [0016]    According to a further embodiment of the present invention, the first energy absorber element has a longitudinal slit, whereby the housing further has an intermediate wall, which is mounted in the area of the slit. 
         [0017]    By slitting the sheet and the division of the housing by the intermediate walls into multiple chambers made possible thereby, the maximum forces on the deck layers may be reduced substantially. 
         [0018]    According to a further embodiment of the present invention, the energy absorber further includes a first attachment area and a second attachment area, whereby the first attachment area is designed for attachment of the energy absorber to the primary structure and whereby the second attachment area is designed for attachment of the energy absorber to the inboard device. 
         [0019]    The attachment areas may make possible, for example, a simple assembly. In this regard, the energy absorber first may be fixedly mounted to a hull- or deck surface or to a support element of the primary structure. Next, then, an inboard device element is connected permanently at the second attachment area with the energy absorber. 
         [0020]    According to a further exemplary embodiment of the present invention, the attachment of the energy absorber to the primary structure or to the inboard device takes place by means of a force- or positive-locking connection. 
         [0021]    Therefore, an energy absorber may be provided, for example, which may be mounted simply. The first attachment region, for example, additionally may have a profile, for example, in the form of a claw element, which is inserted onto a rectangular section of a support. In this regard, the claw element may be designed, for example, such that the energy absorber is held to the support with this insertion so that its fixed weight is held. For final attachment of the energy absorber, the energy absorber then may be fixed by means of screws, rivets or self-locking pins or similar means to the support. 
         [0022]    According to a further exemplary embodiment of the present invention, the energy absorber further has an adjustment element. The adjustment element may change the bending radius of the energy absorber element and therewith, the lever arm. In this manner, a change of the force level may be provided (variable constant performance level as well as progressive or declining performance is thus adjustable). 
         [0023]    In this manner, the force progression may be freely adjusted by continuous change of the cover sheet distance. 
         [0024]    In addition, the force-path progression may be adapted individually by a contour adaptation of the cover sheet. In addition, the energy absorber itself may be structured or contoured, in order to individually adjust a further adaptation of the force-path progression. 
         [0025]    For example, the cover sheet may have a bulge or hump, so that the energy absorber element can be forced to an additional bending, which affects likewise the force level. 
         [0026]    According to a further exemplary embodiment of the present invention, the energy absorber has an energy absorption direction, whereby first upon exceeding of a minimal force (force limiting), which acts in the direction of the energy absorption direction, an energy absorption occurs through the energy absorber. 
         [0027]    The inner device (or the like) may be supported substantially fixedly with correspondingly minimal load, so that it is suitable for normal on-board operation. With increased load, such as through an intense impact of force, a damping is established, in which for example, the energy absorber is pulled in the absorption direction from the housing (or is pushed into the housing). In this manner, correspondingly intense force impacts may be effectively absorbed. 
         [0028]    According to a further exemplary embodiment of the present invention, the use of an energy absorber in an aircraft is provided. 
         [0029]    According to a further exemplary embodiment of the present invention, a method for energy absorption in an aircraft is provided, including a pulling out of a first energy absorber element and a second energy absorber element from the housing, and an absorption of an acceleration energy by plastic deformation of the first energy absorber element and of the second energy absorber element within the housing during the pulling out, whereby the second energy absorber element is arranged parallel to the first energy absorber element and lies flat on this, i. e. abuts the first energy absorber element. 
         [0030]    Further objects and embodiments of the invention are provided in the dependent claims. 
         [0031]    Next, the invention will be described in greater detail with regard to exemplary embodiments in reference to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1A  shows a schematic cross-sectional representation of the energy absorber according to one exemplary embodiment of the present invention. 
           [0033]      FIG. 1B  shows a schematic representation of the energy absorber of  FIG. 1A  in plan view. 
           [0034]      FIG. 2A  shows a schematic cross-sectional representation of an energy absorber according to a further exemplary embodiment of the present invention. 
           [0035]      FIG. 2B  shows a further schematic cross-sectional representation of the energy absorber of  FIG. 2A . 
           [0036]      FIG. 3A  shows a schematic cross-sectional representation of an energy absorber according to a further exemplary embodiment of the present invention. 
           [0037]      FIG. 3B  shows a further schematic cross-sectional representation of the energy absorber of  FIG. 3A . 
           [0038]      FIG. 4A  shows a schematic cross-sectional representation of a further energy absorber according to a further exemplary embodiment of the present invention. 
           [0039]      FIG. 4B  shows a further schematic cross-sectional representation of the energy absorber of  FIG. 4A . 
           [0040]      FIG. 5A  shows a schematic cross-sectional representation of an energy absorber according to a further exemplary embodiment of the present invention. 
           [0041]      FIG. 5B  shows a further schematic cross-sectional representation of the energy absorber of  FIG. 5A . 
           [0042]      FIG. 6A  shows an energy absorber in a schematic cross-sectional representation according to an exemplary embodiment of the present invention. 
           [0043]      FIG. 6B  shows a further schematic cross-sectional representation of the energy absorber of  FIG. 6A . 
           [0044]      FIG. 6C  shows a detail enlargement of a region of the energy absorber of  FIG. 6A . 
           [0045]      FIG. 7A  shows a schematic cross-sectional representation of an energy absorber according to a further exemplary embodiment of the present invention. 
           [0046]      FIG. 7B  shows a further schematic cross-sectional representation of the energy absorber of  FIG. 7A . 
           [0047]      FIG. 8A  shows a schematic cross-sectional representation of an energy absorber with an adjustment element according to a further exemplary embodiment of the present invention. 
           [0048]      FIG. 8B  shows a further schematic cross-sectional representation of the energy absorber of  FIG. 8A . 
           [0049]      FIG. 8C  shows an exemplary force-path-progression of the energy absorber according to the configuration of  FIGS. 8A ,  8 B. 
           [0050]      FIG. 8D  shows the energy absorber of  FIGS. 8A ,  8 B with an actuated adjustment element. 
           [0051]      FIG. 8E  shows a corresponding force-path-progression of the energy absorber according to the configuration of  FIG. 8D . 
           [0052]      FIG. 9A  shows an energy absorber with an adjustment element according to a further exemplary embodiment of the present invention. 
           [0053]      FIG. 9B  shows a corresponding force-path-progression of the energy absorber according to the configuration of  FIG. 9A . 
           [0054]      FIG. 9C  shows the energy absorber of  FIG. 9A  with a different actuated adjustment element. 
           [0055]      FIG. 9D  shows the corresponding force-path-progression of the energy absorber according to the configuration of  FIG. 9C . 
           [0056]      FIG. 10A  shows an energy absorber with an adjustment element according to a further exemplary embodiment of the present invention. 
           [0057]      FIG. 10B  shows the energy absorber of  FIG. 10A  in a further cross-sectional representation. 
           [0058]      FIG. 10C  shows the corresponding force-path-progression of the energy absorber according to the configuration of  FIGS. 10A ,  10 B. 
           [0059]      FIG. 10D  shows the energy absorber of  FIG. 10A  with actuated adjustment elements. 
           [0060]      FIG. 10E  shows the corresponding force-path-progression of the energy absorber according to the configuration of  FIG. 10D . 
           [0061]      FIG. 11A  shows an energy absorber with actuated adjustment elements according to a further exemplary embodiment of the present invention. 
           [0062]      FIG. 11B  shows the corresponding force-path-progression of the energy absorber according to the configuration of  FIG. 11A . 
           [0063]      FIG. 11C  shows a further energy absorber with actuated adjustment elements according to a further exemplary embodiment of the present invention. 
           [0064]      FIG. 11D  shows the force-path-progression of the energy absorber according to the configuration of  FIG. 11C . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0065]    In the following description of the figures, the same reference numerals are used for the same or similar elements. 
         [0066]    The representations in the figures are schematic and not to scale. 
         [0067]      FIG. 1A  shows a schematic cross-sectional representation of an energy absorber according to an exemplary embodiment of the present invention. The energy absorber  100  has a lower housing region  101  and an upper housing region  102 , between which the energy absorber element is mounted. 
         [0068]    The energy absorber  100 , in which this energy absorber elements  1  are installed, is subdivided basically into so-called single deckers with a sheet or with multiple sheets placed in one another and so-called multiple deckers with two or more sheets running opposite to one another (which can comprises respectively again multiple sheets placed in one another). 
         [0069]    Thus, multiple sheets can be nested in one another, in order to achieve for example an optimization of the cover layer load, better volume use or increased force level. 
         [0070]    In addition, the energy absorber  100  includes a fixed support  103  for the energy absorber element  1  and force impact points  105 - 112 ,  115 . 
         [0071]      FIG. 1B  shows the energy absorber of  FIG. 1A  in a representation rotated at 90°. The upper housing part or double-decker sheet  102  has a bore  113  for attachment, for example, to the primary structure of the aircraft. The energy absorber element  1  has a bore  114  for attachment, for example, to an inboard device part of the aircraft. If a force acts now on the housing in the direction of the arrow  116  and a force acts on the absorber element  1  in the opposite direction  117 , then the absorber element is pulled out from the housing by plastic deformation upon exceeding a known minimal force. Thus, energy is absorbed. 
         [0072]    The absorption functions also in the reverse direction, as specifically the energy absorber element  1  is pressed into the housing. The first impact points  105  to  112  and  115  serve on the one hand for connection of the cover sheets  101 ,  102  and for distribution of the occurring forces (symbolized by force line  118  and arrows  119 ,  120 ). 
         [0073]    The structure shown in  FIG. 1  represents the basic form o the single decker. Here, the energy absorber element  1  is braced against the cover layers  101 ,  102  and is transformed upon reaching the trigger force. 
         [0074]      FIGS. 2A ,  2 B shows cross-sectional representations of an energy absorber according to a further exemplary embodiment of the present invention. This structure is principally designed like the structure in  FIG. 1 . By means of the slots of the sheet  1  and the subdivision of the housing  102 ,  101  made possible in this manner by intermediate walls  202  into multiple chambers, the forces may be greatly reduced or uniformly distributed. Reference numeral  201  represents a slot in the sheet, in which an intermediate wall  202  runs. 
         [0075]      FIGS. 3A ,  3 B show a further energy absorber according to a further exemplary embodiment of the present invention in two cross-sectional representations. This structure can be viewed as an independent deformation principle. Since here, however, preferably only one energy absorber element  1  is deformed, this structure is attributed likewise to the single-decker. The sheet is passed around multiple times around rollers  301 ,  302 ,  303 ,  304 ,  305 ,  306 ,  307 . The rollers should be designed to be rotatable, in order to hold the frictional effect at a minimum. 
         [0076]      FIGS. 4A ,  4 B show an energy absorber according to a further exemplary embodiment of the present invention, which belongs to the structure “double deck”. 
         [0077]    Here, the first energy absorber element  1  is braced on one side against the cover layer  102 . A second energy absorber element  3  is provided, which is braced on the other side against the lower cover layer  101 . The energy absorber elements  1 ,  3  are deformed upon reaching the tripper force and roll against one another. 
         [0078]      FIGS. 5A ,  5 B shows an energy absorber according to a further exemplary embodiment of the present invention. This structure is designed principally like the structure of  FIG. 4 . By the placement of two or more sheets  1 ,  2  or  3 ,  4 , the force level can be increased. For example, larger loads can therefore be absorbed. At the same time, one uses the space better and the differently positioned sheets affect a favorable force distribution on the cover layers or cover plates  101 ,  102  through the now existing two force lines  118 . 
         [0079]      FIGS. 6A ,  6 B,  6 C shows a further embodiment of the energy absorber. Here, respectively, two (or more) sheets are placed in one another ( 1 ,  2  or  3 ,  4  or  5 ,  6  or  7 ,  8 ). In addition, the different groups of inlaid sheets are placed respectively over one another. The sheet pair  1 ,  2  is braced with a rolling motion against the sheet pair  3 ,  4  and the sheet pair  5 ,  6 , is braced with a rolling motion against the sheet pair  7 ,  8 . 
         [0080]    The structural space here is used very favorably. The multiple sheets lying over one another acts by their arrangement itself like cover sheets and reduced therefore the forces acting on the cover layers  101 ,  102 . 
         [0081]    In addition, through the adjacent placement of such sheets, the thickness of the energy absorber  100  (that is, the spacing of both cover sheets  101 ,  102 ) with constant force progression may be reduced. This could enable an integration of the energy absorber in a sandwich palette, for example, which can result in turn in reduction of the housing. 
         [0082]      FIGS. 7A ,  7 B show an energy absorber according to a further exemplary embodiment of the present invention. This structure is designated by a slim design. Here, the individual energy absorber elements  1 ,  2 ,  3 ,  4 ,  9 ,  10  are connected to one another via a central tension rod  701 . The differently positioned sheets affect a favorable force distribution on the cover layers  101 ,  102  through the now existing three force lines  1181 ,  1182 ,  1183 . 
         [0083]      FIGS. 8A through 9D  show an energy absorber with an adjustment element according to a further exemplary embodiment of the present invention. The force progression may be adjusted freely by continuous change of the cover plate distance. This adjustment element system can be used for the single decker principle as well as for the double or multiple decker principle. 
         [0084]    The adjustment element system includes a first adjustment element  801 , a second adjustment element  802 , and a cover plate  803 , which can be displaced by actuation of both adjustment elements  801 ,  802 . 
         [0085]    By actuation of the adjustment elements  801 ,  802 , the cover plate  803  can be displaced, such that the energy absorber element  1  is squeezed together more or less intensely. 
         [0086]    In the configuration shown in  FIGS. 8A ,  8 B, the uniform, substantially constant force-path-progression of  FIG. 8C  is provided. 
         [0087]    In the position shown in  FIG. 8D  (here the adjustment elements  801 ,  902  are screwed in more strongly, so that the cover plate  803  presses together the energy absorber element  1  more strongly), the force-path-progression shown in  FIG. 8D  is provided (at higher level than in  FIG. 8C ). 
         [0088]    In the position shown in  FIG. 9A , in which the cover plate  803  is positioned inclined, the force progression shown in  FIG. 9B  is provided. Here, after expenditure of a minimal force, the force progression is not constant, rather decreases upon pulling out of the strip  1 . On the contrary, the force progression increases upon pushing in of the strip. 
         [0089]    The cover plate  803  also can have a different form, for example, a hump or bulge  808 , which leads to bending of the sheet  1  still further in the region  809 , thereby changing the force-path-progression accordingly. 
         [0090]    In the configuration shown in  FIG. 9C , a reverse force progression (see  FIG. 9D ) is provided, in which upon pulling out of the sheet or plate  1 , the force expended therefore increases (and vice versa). 
         [0091]      FIGS. 10A through 11D  show a double decker system with adjustment elements  801 ,  802 ,  805 ,  806  and cover plates  803 ,  807 . 
         [0092]    The force progression resulting from the configuration of  FIGS. 10A ,  10 B is shown in  FIG. 10C . The force progress constantly here upon pulling out or pushing in of the sheet  1 ,  3 . 
         [0093]    If the adjustment elements  801 ,  802 ,  805 ,  806  are screwed in (see  FIG. 10D ), an increased force progression is provided (see  FIG. 10E ). 
         [0094]    If the adjustment elements are screwed in strongly in a different manner, as shown in  FIG. 11A , a force progression that decreases upon pulling out is provided (see  FIG. 11B ). 
         [0095]    If in contrast the adjustment elements are screwed opposite to the configuration of  FIG. 11A  (see  FIG. 11C ), an increased force progression is provided upon pulling out of the strip  1 ,  2  (see  FIG. 11D ). 
         [0096]    The adjustment elements can be positioned also via hydraulic tappet rods, eccentric disks or electric adjustment drive instead of by screws (see  FIGS. 11A and 11C ). 
         [0097]    Thus, the force level of the absorption can be adjusted also very quickly and/or by automation to the individual situation. 
         [0098]    Naturally, also the use of other materials is possible, for example flexible, deformable plastics or other flexible, deformable materials/material mixtures. 
         [0099]    The shown energy absorber can also be used as an energy absorber in so-called tie-rods. Further applications are, for example: 
         [0100]    Energy absorber in tie rods of hatrack chains. A particular effect is the transfer of forces of the released holder onto the hatrack arranged in front of it and therewith a redundancy potential of this retaining concept. Essentially, these principles are useable where a permanent, positive force-fit connection (defined kinematically) is required. 
         [0101]    Energy absorber in undercarriages. 
         [0102]    Energy absorber with belt systems. 
         [0103]    Energy absorber in rudder linkage for large landing flaps and rudders. 
         [0104]    Energy absorber fro seats. 
         [0105]    Energy absorber with the securing of freight. 
         [0106]    Integration of energy absorbers in the attachment points of monuments of the cabin. 
         [0107]    Energy absorber for APUs, in particular for attachment of the APU (“Auxiliary Power Unit”). 
         [0108]    Energy absorber for separating walls or aircraft arrester nets. 
         [0109]    By changing the geometry of the absorber elements, the bending radius and the material properties, the force levels may be varied. In addition, the force level is adjustable by changing spacing of the cover plates. A permanent frictional connection may exist. The system may be impervious to environmental conditions. In addition, the system may be insensitive to diagonal pull (that is, for example, diagonal with reference to the arrow in  FIG. 9A ), which can occur for example with a crash by deformation of the primary structure. Here, a relative displacement of elements/components can occur, which could have as a result a deviation in the pullout direction. 
         [0110]    It should be noted that the term “comprising” does not exclude other elements or steps and the “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. 
         [0111]    It should also be noted that reference signs in the claims shall not be construed as limiting the scope of the claims.