Abstract:
A secure enclosure for resisting attacks using explosives. The secure enclosure has a body defining an opening and a door leaf hingeably coupled to the body for securely closing the opening. The body and door leaf define a cavity in which valuable items may be stored. The secure enclosure also defines a plurality of frangible portions. Each frangible portion comprises a weakened perimeter so that the frangible portions are ejected by the rapid build-up of pressure when an explosion occurs within the secure enclosure, thereby reducing the pressure within the secure enclosure and preserving the integrity of the body and door.

Description:
BACKGROUND  
       [0001]    The present invention relates to improvements in or relating to a secure enclosure. 
         [0002]    Secure enclosures, such as safes, strongrooms, and vaults, are typically used to store valuable items. One particular application of secure enclosures is to house valuable components of an automated teller machine (ATM), such as a cash dispenser, a cash acceptance module, and the like. The value of such components is principally derived from the large amounts of cash stored within them. 
         [0003]    Secure enclosures provided in ATMs (hereinafter “ATM safes”) differ from conventional safes in that ATM safes include apertures. These apertures may be in the form of slots through which media items (such as banknotes) enter and exit a cash dispenser in the ATM safe, and holes through which control cables pass from the cash dispenser to an ATM controller. The ATM safe has to be designed so that these apertures do not compromise the security of the ATM safe. This is typically achieved by strengthening areas around the apertures, for example, with additional areas of steel. 
         [0004]    ATM safes are designed to resist attack from many different types of tools, such as sledgehammers, power drills, and thermal cutting tools. However, it is becoming more common for ATM safes to be subjected to attacks from explosives, such as plastic explosives, or explosive gas (for example, oxyacetylene or butane gas). In a typical attack, an ATM aperture is created or accessed, for example by drilling or cutting through a thin shutter covering an existing aperture, such as a cash dispense slot. The explosive substance (solid or gas) is inserted into the ATM through this aperture then detonated. 
         [0005]    ATM safes can be designed to withstand explosive attacks by strengthening the ATM safe door and the internal corners of the ATM safe. However, explosion-resistant ATMs typically cost several times the price of a similar safe which does not resist an explosive attack. 
         [0006]    It would be advantageous to be able to provide a low cost safe that is resistant to both conventional attacks (from power tools, sledgehammers, and the like) and attacks using explosives. 
       SUMMARY  
       [0007]    According to a first aspect of the present invention there is provided a secure enclosure comprising: a body defining an opening; and a door leaf hingeably coupled to the body for securely closing the opening; the secure enclosure defining a plurality of frangible portions, each frangible portion comprising a weakened perimeter such that the frangible portions are ejected in the event of an explosion occurring within the secure enclosure. 
         [0008]    By virtue of this aspect of the present invention the frangible portions act as valves to relieve the near-instantaneous pressure build-up resulting from an explosion within the enclosure. 
         [0009]    The frangible portions are preferably provided in the body but may also be provided in the door leaf. 
         [0010]    The body may comprise support walls having a composite construction. Alternatively, the body may comprise a single material, such as steel. 
         [0011]    The composite construction may comprise a central material sandwiched between two layers (an external layer on an outer surface of the central material and an internal layer on an inner surface of the central material). The central material may comprise steel, high density concrete, or the like. In one embodiment, the central material comprises high density concrete incorporating a first set of parallel, spaced, rods aligned in a first direction, and a second set of parallel, spaced, rods aligned transverse to the first direction. Other conventional components may be included to improve resistance of the body to attack, for example, fragments of metal may be incorporated into the central material. 
         [0012]    The external layer and the internal layer may be thin relative to the thickness of the central material. 
         [0013]    In embodiments in which the support walls are formed from a single material (such as steel), the frangible portions may be approximately the same depth as the support walls. 
         [0014]    In embodiments in which the support walls have a composite construction of multiple layers, the frangible portions may be approximately the same depth as one of the layers, such as the external layer. Alternatively, the frangible portions may also have a composite construction (typically different to the composite construction of the support walls) and may be approximately the same depth as the support walls. 
         [0015]    Each frangible portion may comprise a portion of the external layer having a weakened perimeter in registration with an aperture defined by the central material. 
         [0016]    The aperture defined by the central material may be filled with a solid material that is lightweight relative to the central material. This would make it more difficult to detect the location of frangible portions by tapping the external or internal layers to detect a hollow sound. 
         [0017]    In some embodiments, although not preferred, each frangible portion may further comprise a portion of the internal layer having a weakened perimeter in registration with both the weakened perimeter of the external layer and the aperture defined by the central material. 
         [0018]    Each weakened perimeter may include a continuous line of reduced thickness, a broken line of reduced thickness, or a perforated line (that is, a discontinuous broken line). The external layer and/or the internal layer may have a coating (plaster (such as polyfilla (trade mark)), plastics, paint, or the like) to provide an aesthetic finish. The coating may cover the weakened perimeters so that the frangible portions are not visible. 
         [0019]    In embodiments in which the weakened perimeter comprises a line of reduced thickness (but not perforations), the weakened perimeter may be provided on an inner surface of the external layer (that is, a surface of the external layer closest to the inside of the enclosure) so that it is not visible from outside the enclosure. 
         [0020]    In any embodiments in which a portion of the internal layer has a weakened perimeter in registration with both the weakened perimeter of the external layer and the aperture defined by the central material, the weakened perimeter may be provided on an inner surface of the internal layer (that is, a surface of the internal layer closest to the central material) so that it is not visible from inside the enclosure. 
         [0021]    Each frangible portion may have a depth less than or approximately equal to the depth of the support walls, and at least one other dimension (height or width) less than approximately 70 mm to ensure that it is not vulnerable to a conventional attack, and to maintain a reasonable probability of passing an international standard for security of safes, such as EN1143. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0022]    This and other aspects of the present invention will be apparent from the following specific description, given by way of example, with reference to the accompanying drawings, in which: 
           [0023]      FIG. 1  is a schematic perspective view of a secure enclosure according to one embodiment of the present invention; 
           [0024]      FIG. 2  is a front view of the secure enclosure of  FIG. 1 ; 
           [0025]      FIG. 3  is a sectional diagram of part (a portion of a support wall) of the secure enclosure of  FIG. 1 ; 
           [0026]      FIG. 4  is a sectional diagram of another part (a frangible portion) of the secure enclosure of  FIG. 1 ; 
           [0027]      FIG. 5  is a front view of the frangible portion of  FIG. 4 ; and 
           [0028]      FIG. 6  is a pictorial perspective view of the secure enclosure of  FIG. 1  immediately after an explosive attack. 
       
    
    
     DETAILED DESCRIPTION  
       [0029]    Reference is first made to  FIG. 1 , which is a schematic perspective view of a secure enclosure  10 , in the form of an ATM safe, according to one embodiment of the present invention. The ATM safe  10  is designed for use in a rear access ATM and comprises a body  12  defining an opening  14  at the rear of the body  12 , and a door leaf  16  hingeably coupled to the body  12  for securely closing the opening  14 . 
         [0030]    A handle (not shown in  FIG. 1 ), a lock (not shown), and engagement bars (not shown) are mounted onto the door leaf  16  to allow the door leaf  16  to be opened and securely closed. The handle, lock, and engagement bars are of the type conventionally used on ATM safes. 
         [0031]    The body  12  comprises three support walls  18   a,b,c,  upstanding from a base  20  to a roof  22 , so that the body  12  defines a cavity  24  in which an ATM cash dispenser (not shown) can be located. 
         [0032]    The support walls  18  and the roof  22  define frangible portions  26  (shown in broken line in  FIG. 1 ). These frangible portions  26  will be described in more detail below. 
         [0033]    In the same manner as for a conventional ATM safe, a cash dispenser mounted in the body  12  has a shutter (not shown) that aligns with an aperture  28  defined by the front support wall  18   b.  Under control of the cash dispenser (not shown), the shutter (not shown) opens and closes the cash dispenser aperture  28 . 
         [0034]    Reference will now also be made to  FIG. 2 , which is a front view of the ATM safe  10  showing the cash dispenser aperture  28 , which is a slot having a width of approximately 300 mm and a height of approximately 65 mm. 
         [0035]    Reference will now also be made to  FIG. 3 , which is a sectional view of a portion of the front support wall  18   b,  illustrated by arrows labeled  40  in  FIG. 2 . In  FIG. 3 , the support wall  18   b  has a composite construction comprising: a central material  42  sandwiched between an external layer  44  on an outer surface of the central material  42  and an internal layer  46  on an inner surface of the central material  42 . The internal layer  46  is adjacent the cavity  24  ( FIG. 1 ). 
         [0036]    The central material  42  comprises high density concrete incorporating a first set of parallel, spaced, steel rods  50  aligned parallel to the base  20 , and a second set of parallel, spaced, steel rods  52  aligned perpendicular to the base  20 . In this embodiment, the central material  42  is approximately 35 mm thick, the external layer  44  is mild steel approximately 2 mm thick, and the internal layer  46  is stainless steel approximately 3 mm thick. The steel rods  50 , 52  are each approximately 8 mm in diameter. 
         [0037]    Reference will now also be made to  FIG. 4 , which is a sectional diagram of a portion of the front wall  18   b  including one of the frangible portions  26 , illustrated by arrows labeled  54  in  FIG. 2 . In this embodiment, every frangible portion  26  has an identical depth, width, and height. 
         [0038]    The frangible portion  26  comprises a weakened perimeter  56  (best seen in  FIG. 5 ) in the form of a series of perforations. The weakened perimeter  56  is a rectangle measuring approximately 200 mm wide and approximately 60 mm high, and comprises a series of anchors  58  measuring 1 mm high and 10 mm wide defined by adjacent slots  59  measuring 1 mm high and 20 mm wide. 
         [0039]    In the areas of the support walls  18  around the frangible portions  26 , the central material  42  is reinforced by additional steel frames  60 . This is to ensure that the areas of support walls  18  adjacent to frangible portions  26  are more resistant to attack than other areas of the support walls  18 . 
         [0040]    In  FIG. 4 , the central material  42  defines a central aperture (not shown) in registration with the weakened perimeter  56 . To ensure that this frangible portion  26  does not sound hollow if tapped by a finger or a tool, a lightweight block  62 , such as a polystyrene or wooden block, is mounted within the central aperture and maintained in position by a loose interference fit. 
         [0041]    To provide an aesthetic finish, and to mask the locations of the frangible portions  26 , a surface finish, such as polyfilla (trade mark), may be applied to the external layer  44  to fill in the slots  59  of the weakened perimeters  56 . A surface finish may also be applied to the internal layer  46  (including the lightweight block  62 ). 
         [0042]    The frangible portion  26  may be considered as (i) only the part of the external layer  44  within the weakened perimeter  56 , or (ii) that part of the external layer  44  within the weakened perimeter  56  in combination with the lightweight block  62 . 
         [0043]    The operation of the ATM safe  10  will now be described with reference to  FIG. 6 , which is a pictorial perspective view of the ATM safe  10  immediately after an explosive has been detonated within the ATM safe  10 .  FIG. 6  is a rear view of the ATM safe  10 , and illustrates the door leaf  16  having a door handle  70  in the closed and locked position to secure the contents of the ATM safe  10 . 
         [0044]    When an explosive is detonated within the ATM safe  10  there is a near-instantaneous build up of pressure in the cavity  24  ( FIG. 1 ). This pressure build up pushes the support walls  18  outwards, and causes the anchors  58  to sheer from the support walls  18 , thereby ejecting the frangible portions  26  from the ATM safe  10 , as illustrated in  FIG. 6 . 
         [0045]    Once the frangible portions  26  have sheered from the support walls  18 , the pressure build up is released because air can escape from the cavity  24  ( FIG. 1 ) through newly-created apertures  80  corresponding to areas of the support walls  18  or roof  22  where the frangible portions  26  were located; that is, the newly-created apertures  80  correspond to the area enclosed by the weakened perimeters  56  and the central apertures (not shown). By allowing the pressure in the cavity  24  to be released through the newly-created apertures  80 , the support walls  18  maintain their integrity, and the ATM safe  10  remains secure. 
         [0046]    Various modifications may be made to the above described embodiment within the scope of the invention, for example, in other embodiments, the frangible portions may have different sizes, and different locations than shown in the above embodiment. In other embodiments, there may be a different number of frangible portions. The number of frangible portions may depend on the volume and design of the secure enclosure. In the above embodiment, every frangible portion has an identical depth, width, and height; whereas, in other embodiments, different sizes of frangible portions may be provided in a secure enclosure. In other embodiments, the shape of the frangible portions may be different to that shown in the above embodiment, for example, the shape may be round, triangular, or irregular (non-geometric). 
         [0047]    In other embodiments, instead of using perforations to provide a weakened perimeter, the external layer  44  may have a reduced in thickness across an area defining a frangible portion  26 . In still other embodiments, the external layer  44  may have a reduced thickness only at the perimeter (not the center) of a frangible portion  26 . 
         [0048]    In other embodiments the support walls may not have a composite construction, they may comprise a single type of material, such as steel. In such embodiments, each frangible portion may comprise an area defined by a reduced thickness perimeter line, a reduced thickness area, or a perforated line. 
         [0049]    In other embodiments, a secure enclosure other than an ATM safe may be provided, for example, a vault having no apertures, or only one aperture for a key.