Patent Publication Number: US-10308422-B2

Title: Foldable RCS container

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Stage Entry of International Patent Application Serial Number PCT/EP2016/051494, filed Jan. 26, 2016, which claims priority to German Patent Application No. DE 10 2015 202 551.9 filed Feb. 12, 2015, the entire contents of both of which are incorporated herein by reference. 
     FIELD 
     The present disclosure generally relates to containers, including containers in which sides are formed from a container wall for reducing an effective radar cross section. 
     BACKGROUND 
     Standard containers have established themselves for storing and transporting goods. In the meantime, said standard containers are also being used in a very much wider spectrum, from temporary residential buildings or offices to mobile operating rooms. 
     ISO 668 standardizes containers for maritime freight. However, this standard today is used far beyond maritime freight, such that these containers have become accepted as the standard also in the rail and truck sectors. The 20 ft and 40 ft containers are most commonly found, but the standard also defines containers with a length of 45 ft or 53 ft. On account of the wide use of these containers, the infrastructure in the logistics sector has also been adapted to said containers. Loading bays or storage spaces are typically designed for these standard containers. 
     In order to save space when containers are not being used, it is known from the prior art for said containers to be folded. A foldable standard container is known from DE 201 11 561 U1, wherein four post elements are movable between a vertical and a horizontal position. A self-unfolding standard container is known from WO 2011/154982 A1. 
     A foldable maritime container is known from WO 2010 085 785 A2. 
     A folding box-shaped unit is known from DE 1 536 121 A. 
     A method for coating surfaces for the purpose of camouflaging them in relation to radar is known from DE 1 956 979 C3. 
     Despite the above, non-foldable containers are mainly used today, since these are substantially more cost-effective and maintenance free. Likewise, the storage and transportation of empty containers is comparatively problem-free since modern container vessels can transport up to 19 000 20-ft containers (TEU: twenty-foot equivalent unit). 
     Standard containers are also increasingly establishing themselves in the defense sector since the former by virtue of their standardization are comparatively easy to handle. However, it is disadvantageous that the standardized containers by virtue of the vertical metallic side walls thereof have a comparatively large radar cross section when stowed on the ship&#39;s deck, and a vessel which transports such containers is thus easy to detect and thus to render vulnerable. For this reason, containers have also been optimized for the defense sector while considering the effective radar cross section. By way of example, a standard container which has a minimized effective radar cross section (RCS) is known from the post-published DE 10 2014 103 601. 
     However, it is often desirable in the defense sector for not only the radar signature but also the visibility to be reduced. While it is indeed known for these standard containers to be provided for example with camouflage paint, this can only represent a limited improvement. Moreover, the incoming and outgoing transportation of material that is no longer required, even of a standard container that is no longer being used, is typically very complex in the defense sector. 
     Therefore a need exists for a container that is optimized for application in the defense sector, said container minimizing the ability for detection and being employable in a reliable manner in the field. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a schematic perspective view of an example container during folding. 
         FIG. 2  is a schematic perspective view of an example container in an unfolded state. 
         FIG. 3  is a schematic view of a first end side of an example container during folding. 
         FIG. 4  is a schematic view of an example folding mechanism. 
         FIG. 5  is a schematic view of an example cladding board. 
     
    
    
     DETAILED DESCRIPTION 
     Although certain example methods and apparatus have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents. Moreover, those having ordinary skill in the art will understand that reciting ‘a’ element or ‘an’ element in the appended claims does not restrict those claims to articles, apparatuses, systems, methods, or the like having only one of that element, even where other elements in the same claim or different claims are preceded by “at least one” or similar language. Similarly, it should be understood that the steps of any method claims need not necessarily be performed in the order in which they are recited, unless so required by the context of the claims. In addition, all references to one skilled in the art shall be understood to refer to one having ordinary skill in the art. 
     The container according to the invention has a floor, a ceiling, a first side wall and a second side wall, a first end wall and a second end wall. The container in the unfolded state is substantially cuboid. The first side wall, the second side wall, the first end wall and the second end wall are formed from a container wall for reducing the effective radar cross section. A container wall is configured for reducing the effective radar cross section when said container wall is configured either for the absorption of radar radiation and/or for the reflection of incident radar radiation at an angle that is dissimilar to the incident angle. In the case of the container wall being configured for the reflection of incident radar radiation at an angle that is dissimilar to the incident angle, said container wall is usually conceived for the reflection of an incident radar ray at an oblique angle, usually at 15°±3°, in relation to the surface of the earth. This corresponds to the most probable threat scenario. The first side wall and the second side wall in the longitudinal direction of the container, mid-height between the floor and the ceiling, are foldable inward into the interior of the container. At least the first side wall has a first cladding board for reducing the effective radar cross section. The first cladding board is permeable to radar rays. The first cladding board furthermore has a reflective agent which reflects radar rays. The reflective agent is embedded in the first cladding board and is aligned so as to be at least partially inclined in relation to a plane of main extent of the first cladding board. 
     Since the reflective agent is internal and thus integrated in the cladding board, wear for example by abrasion, is avoided. The reduction of the effective radar cross section is thus preserved even in the case of the container being regularly folded. 
     In one further embodiment of the invention, the second side wall has a second cladding board for reducing the effective radar cross section. The second cladding board is permeable to radar rays. The second cladding board furthermore has a reflective agent which reflects radar rays. The reflective agent is embedded in the second cladding board and is aligned so as to be at least partially inclined in relation to a plane of main extent of the second cladding board. 
     In one further embodiment of the invention, the first end wall has a third cladding board for reducing the effective radar cross section. The third cladding board is permeable to radar rays. The third cladding board furthermore has a reflective agent which reflects radar rays. The reflective agent is embedded in the third cladding board and is aligned so as to be at least partially inclined in relation to a plane of main extent of the third cladding board. 
     In one further embodiment of the invention, the second end wall has a fourth cladding board for reducing the effective radar cross section. The fourth cladding board is permeable to radar rays. The fourth cladding board furthermore has a reflective agent which reflects radar rays. The reflective agent is embedded in the fourth cladding board and is aligned so as to be at least partially inclined in relation to a plane of main extent of the forth cladding board. 
     The embodiment of a cladding board is described for example in DE 10 2014 103 601 A1, the latter being fully incorporated herein by reference. 
     In one embodiment of the invention, the ceiling is also formed from a container wall for reducing the effective radar cross section. 
     In one further embodiment of the invention, at least the first end wall has a first door. The first door of the first end wall is embodied so as to be double-leafed, having a first door leaf and a second door leaf. The first door is foldable inward in the interior of the container. The first door leaf is embodied in two parts, having a first upper door leaf and a first lower door leaf. The second door leaf is embodied in two parts, having a second upper door leaf and a second lower door leaf. The first upper door leaf, the first lower door leaf, the second upper door leaf, and the second lower door leaf extend across half the height between the floor and the ceiling. The first upper door leaf and the first lower door leaf, and the second upper door leaf and the second lower door leaf, can be connectable. It is an advantage of this embodiment that the container can be tightly closed on account thereof. 
     The unfolded state of the container can be referred to as the receiving position, while the folded state can be referred to as the storage position. 
     In one preferred embodiment, the first door of the first end wall is not only foldable inward into the interior of the container, but can also be opened outward. The first door can preferably be opened outward by at least 90°, more preferably be opened outward by at least 180°, and particularly preferably be opened outward by 270°. 
     In one further embodiment of the invention, the second end wall also has a second door which is configured like the first door. Alternatively, the second end wall can be embodied so as to be foldable such that the second end wall is foldable inward into the interior of the container, toward the ceiling or the floor. 
     In one further embodiment of the invention, the container has post elements, wherein the post elements in the unfolded state connect the ceiling and the floor in a force-fitting manner, wherein the post elements in the unfolded state are disposed on the edges of the cuboid. The post elements are preferably embodied so as to be rigid, thus stabilizing the container in the unfolded state. The post elements are preferably in each case connected in a foldable manner by way of a twistlock. Twistlocks according to ISO 668 are connection elements of standard containers that are located in the corners of the cuboid. In one embodiment, the post elements are in each case connected in a foldable manner with the twistlock that is located on the floor. 
     This is preferable when the container is erected and taken down by hand. In another embodiment, the post elements are in each case connected to the twistlock that is located on the ceiling. This embodiment is preferable when the post elements on that side that faces the floor are connected to the floor by way of a movable element, for example a rack, a threaded spindle, or a rail. 
     In one further embodiment of the invention, the post elements by way of at least two rotatable connection elements are connected to threaded spindles and by way of the threaded spindles to the floor in such a manner that the post elements by rotating the threaded spindles can be aligned so as to be parallel with the floor. A threaded spindle has an encircling trapezoidal thread, for example. On account thereof, a component having an internal thread that sits around the threaded spindle can be displaced along the threaded spindle like on a screw. In one embodiment, the container has four threaded spindles, wherein each post element is connected to one threaded spindle. In one alternative embodiment, the container has two threaded spindles, wherein two post elements are connected to each threaded spindle. The threaded spindle in this embodiment has a first and a second region, wherein a first post element is connected in the one first region, and a second post element is connected in the one second region, wherein the direction of rotation of the trapezoidal thread of the threaded spindle in the two regions is counter-rotating. On account thereof, two post elements of one side can be simultaneously folded by way of a single threaded spindle. It is ensured on account thereof that shearing forces do not arise in the folding of the container. 
     In one further embodiment of the invention, the threaded spindles are driven manually, electrically, hydraulically, or pneumatically. Particularly preferably, the threaded spindles can be driven manually, on the one hand, and electrically, hydraulically, or pneumatically, on the other hand. On account thereof, a container in a field camp, for example, can be unfolded or folded even without any technical auxiliary equipment. 
     In one further embodiment of the invention, the container is a container according to ISO 668, particularly preferably a 20-ft container according to ISO 668. 
     In one further embodiment of the invention, the container is secured in terms of ballistics. A ballistic protection can be established for example by attaching Kevlar to the inside or the outside. On account thereof, the interior is protected from minor projectiles or shrapnel. This embodiment is preferable when the container is to serve as a working space, for example in a field camp. 
     The preferred container wall has the advantage that the reflective agent is integrated in the cladding board such that the surface of the cladding board does not comprise any regions with an alignment that is inclined in relation to the plane of main extent. In this way, the container can be embodied so as to conform to ISO 668, and the radar cross section (RCS) can be simultaneously reduced since the radar-reflecting part in relation to the plane of main extent is partially inclined and the incident radar rays thus are not reflected directly back to the emitter of the radar waves. In other words, the reflective agent is configured in particular in such a manner that incident radar rays that impact the reflective agent along a direction of incidence that is substantially perpendicular to the plane of main extent are reflected by the reflective agent in an outgoing direction that deviates from the antiparallel direction of incidence. Vectors which are parallel but have an opposite direction are understood to be antiparallel. The integration of the reflective agent in the cladding board moreover has the advantage that the container wall can be produced in a simple manner. 
     According to one preferred embodiment of the container wall it is provided that the reflective agent has a sawtooth profile. On account of the sawtooth profile, a reflective agent in which the reflective faces are at all times inclined in relation to the plane of main extent, and thus a reflection of incident radar rays directly back to the emitter is suppressed, can be provided in a particularly efficient manner. It is simultaneously prevented by the sawtooth profile that the thickness of the reflective agent perpendicular to the plane of main extent becomes excessive, thus impeding the assembly. The sawtooth profile is preferably implemented in that the reflective agent is constructed from a plurality of first and second reflective inclines which are disposed in an alternating manner along a direction of main extent of the reflective agent. 
     According to one preferred embodiment of the container wall, it is provided that in each case a first angle is configured between the plane of main extent and the first reflective incline, and in each case a second angle is configured between the plane of main extent and the second reflective incline, wherein the first angle and the second angle are dissimilar, and wherein in particular the first angle is smaller than the second angle. Advantageously, the first and the second reflective inclines are thus inclined dissimilarly in relation to the plane of main extent. It is conceivable that the first angle is between 5° and 60°, particularly preferably between 10° and 30°, most particularly preferably between 15° and 25°, and/or that the second angle is between 60° and 100°, particularly preferably between 70° and 90°, most particularly preferably is substantially 85°. 
     According to one preferred embodiment of the container wall, it is provided that the cladding board comprises a substantially rigid sandwich board. Advantageously, the container wall is thus comparatively light and can be produced in a cost-effective manner. The sandwich board preferably has two cover layers and a core that is disposed between the two cover layers. The cover layers in each case preferably comprise a glass-fiber reinforced plastics material, while the core preferably comprises a foam core. The reflective agent is embedded in the core in particular. 
     According to one preferred embodiment of the container wall, it is provided that the reflective agent comprises a conductive film/foil. For example, it is conceivable that the reflective agent comprises a metal insert, a woven fabric, and/or a carbon-fiber reinforced plastics-material insert. Advantageously, a high coefficient of reflection of the reflective agent is thus achieved, on the one hand, and a cost-effective and simple production, on the other hand. 
     According to one embodiment of the container wall, the container wall is composed of a structural wall that is not configured for reducing the effective radar cross section (RCS), for example of a metallic wall to which cladding boards which are configured for reducing the effective radar cross section (RCS) are applied. The cladding board herein is preferably configured such as has been described in the context of the container wall which is configured for reducing the effective radar cross section (RCS). This embodiment is preferable for retrofitting foldable containers which are not optimized in terms of RCS. 
     In one further embodiment of the invention, the RCS wall parts on account of the construction of the latter, in particular of the sandwich construction, are resistant to sea wash. The frame construction is preferably conceived such that said frame construction can absorb the forces caused by sea wash on the RCS wall parts. The movable and non-movable parts of the frame construction are preferably made from high-tensile, high-alloy steel types, so as to correspond to the stresses to be expected, said steel types without any further reinforcement elements directing the forces by way of the twistlock elements into the structure of the vessel. In the case of extreme conditions that are to be potentially expected, the RCS container, like the normal standard container, can additionally also be lashed at the upper twistlock elements. 
     In one further embodiment of the invention, the container has a seal. To this end, the container can have rubber seals of various embodiments which seal the container in the locked state in a wind and water-tight manner, preferably according to protection class IP23. 
     The container  10  shown in  FIG. 1  to  FIG. 4  is a 20-ft container according to ISO 668. The container has the usual features of a standard container, in particular the standardized container corners for locking the container. 
     The container  10  in  FIG. 1  is shown while the container is being unfolded. The container  10  has a floor  20  and a ceiling  30  and two side walls  40 . The side walls  40 , mid-height between the floor  20  and the ceiling  30 , are foldable inward into the interior of the container  10  by means of a folding joint  42 . The container  10  has post elements  50  for stabilizing the container  10  in the unfolded state. These post elements  50  are connected in a foldable manner to the container corners on the ceiling  30 . The post elements  50  are connected to the floor  20  by way of threaded spindles  80  (shown in  FIG. 4 ). On account thereof, the post elements  50  by rotating the threaded spindles  80  can be aligned so as to be parallel with the floor  20 . The drive of the threaded spindles  80  is established by way of the crank  70 . The container  10  on the first end wall has a double-leafed door which is composed of two upper door leaves  62  and two lower door leaves  64 . The upper door leaves  62  and the lower door leaves  64  are folded inward into the interior of the container  10  and come to bear on the side walls  40 . On account thereof, the container  10  can be completely folded in a compact manner. 
     The container  10  in  FIG. 2  is shown so as to be unfolded, the door on the first end wall is closed, the post elements  50  are vertical and connect the floor  20  and the ceiling  30  in a force-fitting manner. The crank  70  is preferably removable in order for the container  10  to have external dimensions according to ISO 668 and to be stackable and transportable in a corresponding manner. 
     The container  10  in  FIG. 3  is in a perspective front view. As opposed to  FIG. 1 , it can be more readily seen how the upper door leaf  62  and the lower door leaf  64  are folded inward into the interior of the container  10  so as to be against the side wall  40 . 
       FIG. 4  schematically shows the mechanism of the container  10 . The standardized container corners for locking the container can be seen at the corners of the cuboid. In order for the container  10  to be unfolded or folded, the post element  50  by rotation of the threaded spindle  80 , the latter being rotated by way of the drive  82 , is moved to a position that is parallel with the floor  20  or to a vertical position. The drive  82  is preferably drivable both by means of the crank  70  shown in  FIG. 1  as well as by electric means. 
     A schematic sectional view of a cladding board  110  for reducing the effective radar cross section is illustrated in  FIG. 5 . The cladding board  110  is configured in the form of a rigid or semi-rigid sandwich board. To this end, the cladding board  110  comprises two cover layers  120  from a glass-fiber reinforced plastics material (GRP) and a core  130  which is disposed between the two cover layers  120 . The core  130  comprises a foam core, preferably a polyurethane foam (PUR). A high load capacity and a high rigidity and at the same time a very low weight result on account of the composite of the cover layers  120  and the foam core. Moreover, the cladding board  110  is permeable to radar rays  150 , such that no noteworthy radar echo emanates from the planar surface of the cladding board  110  which extends along a plane of main extent  160 . The cladding board  110  furthermore has a reflective agent  140  which is integrated in or adhesively bonded into the foam core, respectively. The reflective agent  140  is configured in the form of a metal insert, on account of which radar rays  150  are reflected by the reflective agent  140 . The reflective agent  140  is configured in the form of a sawtooth profile or configured in a stepped manner, respectively, such that the part-regions of the surface of the reflective agent  140  are at all times inclined in relation to the plane of main extent  160  of the cladding board  110 . The reflective agent  140  alternatively comprises a woven fabric (gauze) and/or a carbon-fiber reinforced plastics-material insert (GRP). In order for the cladding board  110  to nevertheless be able to be configured as thin as possible along a direction that is perpendicular to the plane of main extent  160 , the reflective agent  140  is constructed from a plurality of first and second reflective inclines  170 ,  180  which are disposed in an alternating manner along a direction of main extent  190  of the reflective agent  140  that is parallel with the plane of main extent  160 . Herein, a first angle  200  is in each case configured between the plane of main extent  160  and the first reflective incline  170 , and in each case a second angle  210  is configured between the plane of main extent  160  and the second reflective incline  180 , wherein the first angle  200  is at all times smaller than the second angle  210 . Furthermore, the face of the second reflective incline  180  is at all times smaller than the face of the first reflective incline  170 . The reflective inclines  170 ,  180  which are inclined in relation to the plane of main extent  160  ensure that incident radar rays  150  that impact the reflective agent  140  along a direction of incidence that is substantially perpendicular are reflected by the reflective agent  140  in an outgoing direction that deviates from the antiparallel direction of incidence. In other words, radar rays  150  which are emitted by a radar source  220  and impact the cladding board  110  perpendicularly, are not reflected in a frontal manner back to the radar source  220  but are directed by the reflective agent  140  in other spatial directions having directional proportions that are parallel with the plane of main extent  160 . This has the advantage that a radar apparatus that is connected to the radar source  220  receives a comparatively small radar echo, impeding the detection by radar. The effective radar cross section (RCS) is thus significantly reduced. 
     REFERENCE SIGNS 
       10  Container 
       20  Floor 
       30  Ceiling 
       40  Side wall 
       42  Folding joint 
       50  Post element 
       62  Upper door leaf 
       64  Lower door leaf 
       70  Crank 
       80  Threaded spindle 
       82  Drive 
       110  Cladding board 
       120  Cover layer 
       130  Core 
       140  Reflective agent 
       150  Radar rays 
       160  Plane of main extent 
       170  Reflective incline 
       180  Reflective incline 
       190  Direction of main extent 
       200  First angle 
       210  Second angle 
       220  Radar source