Abstract:
A modular block apparatus includes first and second blocks, each block having a generally upwardly protruding locking member and an internal recess sized to receive the locking member of the other block, such that the blocks can be assembled with one block above the other. The blocks are secured together in a vertical direction by relative lateral movement of the locking member and the internal recess. A locking device is provided to prevent relative lateral movement of the locking member and the internal recess so as to retain the blocks in a connected condition. The locking member may be an integral hook, a separate hook, or a cylindrical locking rod. If a hook is used, its orientation relative to the block may be varied. A variety of structures may be built up from the modular blocks.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to modular construction systems and more particularly to a system of modular blocks which can be connected in various ways. 
         [0002]    Various construction systems exist in which identical or similar modular elements are built up into larger structures. Known examples of modular building elements include bricks and concrete blocks. While these provide a modular configuration, they lack a self-connecting feature and must be assembled with separate fasteners, adhesives, or mortar. 
         [0003]    Systems of interlocking construction blocks are also known. These are typically used for toys or small-scale models, and typically rely on friction or snap-type connectors. While these systems provide a self-connecting feature, the user is limited to preformed blocks which have fixed connector elements. 
         [0004]    Accordingly, there is a need for a modular construction element having a connector that can be configured in different ways. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    Therefore, it is an object of the invention to provide a block that can be used to build up modular structures. 
         [0006]    It is another object of the invention to provide a modular block with a connector that can be oriented in different directions. 
         [0007]    These and other objects are achieved by the present invention, which in one embodiment provides a modular block apparatus, including: first and second blocks, each block having a generally upwardly protruding locking member and an internal recess sized to receive the locking member of the other block such that the blocks can be assembled with one block above the other. The blocks are secured together in a vertical direction by relative lateral movement of the locking member and the internal recess. Means are provided for preventing relative lateral movement of the locking member and the internal recess so as to retain the blocks in a connected condition. 
         [0008]    According to another embodiment of the invention, a modular block apparatus includes: a block with top and bottom surfaces, a front sidewall, and an interior cavity formed therein, the interior cavity defining a locking recess communicating with the bottom surface, and a lug receptacle communication with the top surface; and a locking lug received in the lug receptacle, the locking lug having a laterally-extending hook protruding above the top surface. 
         [0009]    According to another embodiment of the invention, the lug receptacle includes at least one protruding side boss disposed therein; and the locking lug includes at least one lug boss disposed thereon. The lug bosses and the side bosses are arranged such that the hook faces in a selected one of a plurality of directions relative to the front sidewall, and the lug is retained, by engagement of the bosses, against withdrawal from the lug receptacle in a vertical direction. 
         [0010]    According to another embodiment of the invention, the interior cavity includes a generally vertical portion extending between the lug receptacle and the locking recess. 
         [0011]    According to another embodiment of the invention, the modular block apparatus further includes a key disposed in the vertical portion which prevents lateral motion of the locking lug. 
         [0012]    According to another embodiment of the invention, the key prevents lateral motion of a hook received in the locking recess. 
         [0013]    According to another embodiment of the invention, the block has at least one generally vertical edge, and includes: at least one open corner slot formed in the vertical edge; and a generally vertically-extending corner hole disposed near the vertical edges and intersecting the corner slot. 
         [0014]    According to another embodiment of the invention, B 7  the modular block further includes: a connector plate having a thickness sized to fit in the corner slot, and a connector pin hole formed therethrough; and a connector pin sized to fit into the corner hole and the connector pin hole to retain the connector plate in the corner slot. 
         [0015]    According to another embodiment of the invention, the connector plate further includes additional connector pin holes formed therethrough and is sized for engaging corner slots of at least two adjacent blocks. 
         [0016]    According to another embodiment of the invention, the modular block apparatus of claim B 6  further includes a finish element having: a exterior surface having a desired shape; and a laterally-extending connector plate having a thickness sized to fit in the corner slot, and a connector pin hole formed therethrough. 
         [0017]    According to another embodiment of the invention, the hook is substantially smaller than the locking recess. 
         [0018]    According to another embodiment of the invention, the block includes a plurality of laterally-extending hooks protruding above the top surface, and each of the hooks is substantially smaller than the locking recess. 
         [0019]    According to another embodiment of the invention, the hook is substantially larger than the locking recess. 
         [0020]    According to another embodiment of the invention, the block includes a plurality of laterally-extending hooks protruding above the top surface, and each of the hooks is substantially smaller than the locking recess. 
         [0021]    According to another embodiment of the invention, a modular block apparatus includes: a block with top and bottom surfaces, and at least one generally cylindrical core passage extending between the top and bottom surfaces; and a locking assembly received in the core passage, the locking assembly including: a core sized to be received in the core passage and having a through-bore extending therethrough, the through-bore defining alternating core grooves and lands; a locking rod having a array of alternating rod grooves and lands complementary to the core grooves and lands; and means for retaining the locking rod in engagement with the core with the locking rod protruding from the top surface. 
         [0022]    According to another embodiment of the invention, the retaining means comprise a rod key received in the through-bore and urges the locking rod laterally against the core grooves and lands. 
         [0023]    According to another embodiment of the invention, the core passage includes at least one key slot extending laterally therefrom, the key slot being in communication with the bottom surface; and the core carries at least one core key which is moveable between a retracted position and a laterally-extended position. Engagement of the locking means causes the core key to move to the laterally-extended position, where the core key engages the core key slot to prevent withdrawal of the core assembly from the core passage. 
         [0024]    According to another embodiment of the invention, the modular block apparatus of claim C 4  further includes: a connector plate having a thickness sized to fit in the connector slot, and a connector pin hole formed therethrough; and a connector pin sized to fit into the core passage and the connector pin hole to retain the connector plate in the connector slot. 
         [0025]    According to another embodiment of the invention, the connector plate has a generally cylindrical stud protruding therefrom, the stud including a land sized and shaped to engage the core grooves and lands. 
         [0026]    According to another embodiment of the invention, the block includes a plurality of core passages of different diameters formed therein. 
         [0027]    According to another embodiment of the invention, the block is a generally rectangular solid. 
         [0028]    According to another embodiment of the invention, the block is curved. 
         [0029]    According to another embodiment of the invention, the block is trapezoidal. 
         [0030]    According to another embodiment of the invention, the block includes a pair of lobes connected by a relatively narrow waist. 
         [0031]    According to another embodiment of the invention, a modular block apparatus includes: a block with top and bottom surfaces, a front sidewall, and an interior space formed therein. The block includes; first and second spaced-apart side members each having an inner surface and an outer surface; and at least one locking lug disposed between the side members, the locking lug having upper and lower notches formed near each its upper and lower ends, respectively, so as to define upper and lower laterally-extending hooks, wherein the upper hook protrudes from the top surface, and is sized and shaped to engage a lower notch of a second block. 
         [0032]    According to another embodiment of the invention, the hook extends towards the front sidewall. 
         [0033]    According to another embodiment of the invention, the hook extends generally perpendicular to the front sidewall. 
         [0034]    According to another embodiment of the invention, the side members and the locking lug are a single integral component. 
         [0035]    According to another embodiment of the invention, the modular block apparatus further includes at least one generally vertical key groove formed in the side members. 
         [0036]    According to another embodiment of the invention, the modular block apparatus further includes a key received in the interior space and having an alignment rail which engages the key groove, the key extending between upper and lower positioned blocks to prevent relative lateral movement thereof. 
         [0037]    According to another embodiment of the invention, the key includes at least two spaced-apart alignment rails which are adapted to engage respectively key grooves of two laterally-adjacent blocks to prevent separation thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
           [0039]      FIG. 1  is a perspective view of a modular block constructed in accordance with the present invention; 
           [0040]      FIG. 2  is a another perspective view of the modular block of  FIG. 1 ; 
           [0041]      FIG. 3A  is a perspective view of a pair of modular blocks constructed in accordance with the present invention in position to be connected; 
           [0042]      FIG. 3B  is a perspective view of the modular blocks of  FIG. 3A  in a partially contacting position; 
           [0043]      FIG. 3C  is a perspective view of the modular blocks of  FIG. 3B  in a fully contacting position; 
           [0044]      FIG. 3D  is a perspective view of the modular blocks of  FIG. 3C  in a fully engaged position; 
           [0045]      FIG. 3E  is a perspective view of the modular blocks of  FIG. 3D , along with a locking key about to be inserted therein; 
           [0046]      FIG. 3F  is a perspective view of the modular blocks of  FIG. 3E , with a locking key partially inserted therein; 
           [0047]      FIG. 3G  is a perspective view of the modular blocks of  FIG. 3F , with a locking key fully inserted therein; 
           [0048]      FIG. 4A  is a perspective view of a modular block along with a connector plate and connector pin; 
           [0049]      FIG. 4B  is a perspective of a plurality of modular blocks connected with connector plates and pins; 
           [0050]      FIG. 5A  is a perspective view of a modular block along with a connector plate, connector pin, and a finish element; 
           [0051]      FIG. 5B  is a perspective view of a plurality of modular blocks connected with connector plates and pins, and having finish elements attached thereto; 
           [0052]      FIG. 6  is a perspective view of a plurality of modular blocks having locking elements oriented in varied directions; 
           [0053]      FIG. 7  is a perspective view of a structure built-up from a plurality of modular blocks having locking elements oriented in varied directions; 
           [0054]      FIG. 8  is a perspective view of a structure built-up from a plurality of modular blocks having locking elements oriented in the same direction; 
           [0055]      FIG. 9  is a perspective view of a truss structure built-up from a plurality of modular blocks; 
           [0056]      FIG. 10  is a perspective view of a wall structure built-up from a plurality of modular blocks; 
           [0057]      FIG. 11  is a perspective view of a group of modular blocks of different sizes; 
           [0058]      FIG. 12  is a perspective view of a modular block adapted to be connected to a plurality of smaller modular blocks; 
           [0059]      FIG. 13  is a perspective view of the modular block of  FIG. 12  connected to a plurality of smaller modular blocks; 
           [0060]      FIG. 14  is a perspective view of another modular block adapted to be connected to a plurality of smaller modular blocks; 
           [0061]      FIG. 15  is a perspective view of the modular block of  FIG. 14  connected to a plurality of smaller modular blocks; 
           [0062]      FIG. 16  is a top perspective view of a modular block constructed according to an alternative embodiment of the present invention; 
           [0063]      FIG. 17  is a bottom perspective view of the modular block of  FIG. 16 ; 
           [0064]      FIG. 18  is an enlarged view of a portion of the top of the modular block of  FIG. 16 ; 
           [0065]      FIG. 19  is an enlarged view of a portion of the bottom of the modular block of  FIG. 16 ; 
           [0066]      FIG. 20  is a perspective view of a locking assembly for use with the modular block of  FIG. 16 ; 
           [0067]      FIG. 21  is a top perspective view of a modular block having a locking assembly installed therein; 
           [0068]      FIG. 22  is an enlarged view of a portion of the top of the modular block of  FIG. 21 ; 
           [0069]      FIG. 23  is an enlarged view of a portion of the bottom of the modular block of  FIG. 21 ; 
           [0070]      FIG. 24A  is a perspective view of a core forming a portion of a locking assembly; 
           [0071]      FIG. 24B  is a perspective view of the core of  FIG. 24A  with a locking rod about to be inserted therein; 
           [0072]      FIG. 24C  is a perspective view of the core and locking rod of  FIG. 24B  connected together; 
           [0073]      FIG. 24D  is a perspective view of the core and locking rod of  FIG. 24C  with a rod key about to be inserted therein; 
           [0074]      FIG. 24E  is a perspective view of the core and locking rod of  FIG. 24C  with a rod key fully inserted therein; 
           [0075]      FIG. 25  is a perspective view of a lower end of a rod key; 
           [0076]      FIG. 26  is a perspective view of a core along with a rod key and a pair of core keys; 
           [0077]      FIG. 27  is a perspective view of a plurality of modular blocks connected together; 
           [0078]      FIG. 28  is a perspective view of a connector plate; 
           [0079]      FIG. 29  is perspective view of a connector plate disposed in a groove of a modular block; 
           [0080]      FIG. 30  is a perspective view of the modular block and connector plate of  FIG. 29  with a connector pin inserted therein; 
           [0081]      FIG. 31  is a perspective view of a pair of modular blocks connected end-to-end with a connector plate and connector pins; 
           [0082]      FIG. 32  is a perspective view of another type of connector plate; 
           [0083]      FIG. 33  is a perspective view of a plurality of modular blocks of varying sizes connected together; 
           [0084]      FIG. 34  is a perspective view of another finish element; 
           [0085]      FIG. 35  is a perspective view of a modular block with a plurality of finish elements connected thereto; 
           [0086]      FIG. 36  is a perspective view of a rotational connector plate; 
           [0087]      FIG. 37  is a perspective view of a modular block with the connector plate of  FIG. 36  attached thereto; 
           [0088]      FIG. 38  is a perspective view of a plurality of modular blocks connected together; 
           [0089]      FIG. 39  is a perspective view of a plurality of modular blocks of varying sizes connected together; 
           [0090]      FIG. 40  is a perspective view of the components of a locking assembly of a first size; 
           [0091]      FIG. 41  is a perspective view of the components of a locking assembly of a second size; 
           [0092]      FIG. 42  is a perspective view of the components of a locking assembly of a third size; 
           [0093]      FIG. 43  is a schematic top view of a representative hole pattern in a modular block; 
           [0094]      FIG. 44  is a perspective view of a wheeled vehicle constructed from modular blocks; 
           [0095]      FIG. 45  is partially exploded view of the vehicle of  FIG. 44 ; 
           [0096]      FIG. 46  is a perspective view of a curved modular block; 
           [0097]      FIG. 47  is a perspective view of a cylindrical structure assembled from the modular blocks shown in  FIG. 46 ; 
           [0098]      FIG. 48  is a perspective view of a structure assembled from a combination of curved and straight modular blocks; 
           [0099]      FIG. 49  is a perspective view of trapezoidal modular block; 
           [0100]      FIG. 50  is a perspective view of a structure assembled from the trapezoidal modular blocks shown in  FIG. 49 ; 
           [0101]      FIG. 51  is perspective view of a lobed modular block; 
           [0102]      FIG. 52  is a perspective view of a wall structure assembled from the lobed modular blocks shown in  FIG. 51 ; 
           [0103]      FIG. 53  is a perspective view of the wall structure of  FIG. 52  in a pivoted position; 
           [0104]      FIG. 54  is a perspective view of a structure assembled from different shapes of modular blocks; 
           [0105]      FIG. 55  is a perspective view of a modular block constructed in accordance with another alternative embodiment of the present invention; 
           [0106]      FIG. 56  is an exploded perspective view of the block shown in  FIG. 55 ; 
           [0107]      FIG. 57  is a perspective view of a variation of the block shown in  FIG. 55 ; 
           [0108]      FIG. 58  is a perspective view of a key for use with the block of  FIG. 55 ; 
           [0109]      FIG. 59  is another perspective view of the key shown in  FIG. 58 ; 
           [0110]      FIG. 60  is a perspective view of an alternative key for use with the block shown in  FIG. 55 ; 
           [0111]      FIG. 61  is another perspective view of the key shown in  FIG. 60 ; 
           [0112]      FIG. 62  is a partially exploded perspective view of a structure built up from the blocks shown in  FIGS. 55 and 57 ; and 
           [0113]      FIG. 63  is a perspective view of the structure shown in  FIG. 62  showing keys being inserted therein. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0114]    Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,  FIG. 1  illustrates an exemplary modular block  10  constructed according to the present invention. The modular block  10  includes a top surface  12 , a bottom surface  14 , and front, rear, left and right sidewalls  16 ,  18 ,  20 , and  22 , respectively. An interior cavity  24  is formed in approximately the center of the modular block  10 . The interior cavity  24  includes a generally vertical portion  26  which extends between a locking recess  28  adjacent the bottom surface  14  of the modular block  10 , and a lug receptacle  30  adjacent the top surface  12  of the modular block  10 . A ledge  32  extends laterally partway into to the locking recess  28 . The lug receptacle  30  is a parallel-sided opening having an end boss  34  extending across an end wall thereof at a selected distance from the top surface  12 , and a pair of spaced-apart side bosses  36  and  38  disposed on opposite side walls thereof. 
         [0115]    A four-faced locking lug  40  includes an inverted “L”-shaped hook  42  which is sized and shaped to engage the locking recess  28  disposed at its upper end. A lug boss  44  is disposed at each of the lower corners of the locking lug  40 . The lug bosses  44  are disposed in a pattern so that they define a lateral slot  46  around the periphery of the locking lug  40 , which communicates with a vertical slot  48  on each of the faces of the locking lug  40 . 
         [0116]    As can be seen in  FIG. 1 , the locking lug  40  is assembled to the modular block  10  by first inserting it into the lug receptacle  30  in a downwards direction. The side bosses  36  and  38  pass into opposed ones of the vertical slots  48 . Once the lug bosses  44  have cleared the side bosses  36  and  38  and the end boss  34  in a vertical direction, the locking lug  40  is then shifted laterally so that two of the lug bosses  44  are aligned with the end boss  34 , and two of the lug bosses  44  are aligned with the side bosses  36  and  38 . In this position, the locking lug  40  is prevented from being withdrawn vertically from the lug receptacle  30 . 
         [0117]    The dimensions, material, and surface finish of the locking lug  40  may be selected to provide the desired interface with the lug receptacle  30 . For example, if an easily-disassembled joint is desired, a small clearance may be provided between the exterior of the locking lug  40  and the lug receptacle  30 . If a more permanent joint is desired, the locking lug  40  may be provided with a tighter fit in the lug receptacle  30 , for example by providing a slight interference fit, or by providing a relatively rough surface finish. 
         [0118]      FIG. 2  illustrates the modular block  10  with the locking lug  40  assembled thereto. In the illustrated example the hook  42  of the locking lug  40  extends towards the left sidewall  20  of the modular block  10 . However, it will be appreciated that the locking lug  40  may be assembled to the modular block  10  so that it points in any one of four directions. 
         [0119]    The modular block  10  and the locking lug  40  may be constructed of any material which is suited to the application for which the modular block  10  is to be used and which can be formed into the necessary dimensional features. For example, the modular block  10  may be used as a toy, a modeling element, or a light structural element, in which case it may be molded from a material such as plastic resin. The modular block  10  may also be used for heavier structural applications, in which case it may be formed from materials such as concrete, wood or engineered wood materials, pressed fiber, metals, or fiber composite materials. Specific applications of the modular blocks  10  are discussed in more detail below. 
         [0120]      FIGS. 3A-3G  illustrates the two identical modular blocks  10  and  10 ′ to form a larger structure. Modular block  10  is provided with a locking lug  40  having a hook  42  as described above. As shown in  FIGS. 3B ,  3 C and  3 D, the hook  42  is inserted into the locking recess  28 ′ of the block  10 ′ and then shifted laterally so that the hook  42  is disposed behind the ledge  32 ′ of the locking recess  28 ′. This prevents the modular blocks  10  and  10 ′ from being disconnected in a vertical direction. 
         [0121]    To secure the blocks together, a key  50  is inserted into the vertical portion  26 ′ (see  FIGS. 3E and 3F ). The key  50  is an elongated member sized to fit into the vertical portion  26 ′ of the cavity  24 ′ (identical to cavity  24 ). As shown in  FIG. 3G , the presence of the key  50  prevents lateral motion of the hook  42  relative to the locking recess  28 ′. The key  50  may be provided with a cut-back edge  52  that engages a shelf  54  of the lug receptacle (best seen in the identical block  10  of  FIG. 2 ), to prevent the key  50  from falling out of the bottom of the modular blocks  10  and  10 ′. As noted above with respect to the locking lug  40 , the dimensions, materials, and surface finish of the key  50  may be selected to prevent unintended withdrawal. 
         [0122]    As shown in  FIG. 2 , the modular block  10  includes an array of laterally-extending corner slots  56  formed in each of its vertical edges. A corner hole  58  passes through the modular block  10  near each of its vertical edges and thus intersects the corner slots  56  formed along each vertical edge.  FIG. 4A  illustrates components used to connect two or more modular blocks  10  together laterally, including a connector pin  60 , and various connector plates  62 ,  64 ,  66 , and  68 . The connector pin  60  is an elongated pin sized to fit the corner hole  58 . It may include an enlarged head  70  to prevent it from falling through the modular block  10 . Each connector plate is a flat member having a thickness sized to fit in one of the corner slots  56  of a modular block  10 , and one or more connector pin holes  72 . In the illustrated example, the connector plate  62  has a single hole and is sized to fill in a corner slot  56  but not to perform any joining function. The connector plate  64  is rectangular and has two connector pin holes  72  therein. The connector plate  66  is “L”-shaped and has three connector pin holes  72 . Finally, the connector plate  68  is square and has four connector pin holes  72  therein. 
         [0123]      FIG. 4B  illustrates several modular blocks  10 ,  10 ′ and  10 ″ connected together. The modular blocks  10 ,  10 ′ and  10 ″ meet at a common vertical edge  74 , and connector plates  68  are inserted into corner slots  56  of each of the modular blocks  10 ,  10 ′, and  10 ″. A connector pin  60  is then inserted into the corner holes  58  of each of the modular blocks  10 ,  10 ′, and  10 ″. This secures each of the modular blocks  10 ,  10 ′, and  10 ″ to the connector plates  68  and thus secures the modular blocks  10 ,  10 ′, and  10 ″ to each other, in both lateral and vertical directions. 
         [0124]      FIG. 5A  illustrates a modular block  10  along with a connector pin  60 , connector plates  62 - 68 , and a finish element  76 . The finish element  76  has a planar inner side  78  which is sized and shaped to mate with a side wall of the modular block  10 . The inner side  78  includes one or more connector tabs  80  with connector pin holes  72  therein. The connector tabs  80  are positioned and sized to fit into corner slots  56  of the modular block  10 . The finish element  76  has an exterior surface  82  with one or more sides or facets which are formed into a desired shape. In the illustrated example, the exterior surface of the finish element  76  is shaped to form a portion of a cylinder. 
         [0125]      FIG. 5B  illustrates several modular blocks  10 ,  10 ′,  10 ″, and  10 ′″ connected together with several finish elements  76 , using the connector plates  68 , connector tabs  80 , and connector pins  60  as described above to form a solid structure with a cylindrical outer surface. As can be observed from  FIG. 5B , the use of finish elements  76  allows the creation of structures that are essentially modular, but which have arbitrary external shapes. 
         [0126]      FIG. 6  illustrates a plurality of building elements  84 . Each of these building elements  84  has multiple “L”-shaped hooks  42  extending from an upper surface thereof, and multiple locking recesses  26  on a lower surface thereof. The building elements  84  can be made as a single element, or built up from individual modular blocks  10 . The direction that each hook  42  faces can be arbitrarily selected to suit a particular application. In  FIG. 6 , each hook labeled  42 A is facing towards the left of the page, each hook labeled  42 B is facing towards the bottom of the page, each hook labeled  42 C is facing towards the right of the page, and each hook labeled  42 D is facing towards the top of the page. If the eight hooks  42  on each building element  84  are divided into groups of four, there are then 16 possible combinations of hook directions.  FIG. 7  illustrates a structure which is built up from building elements  84  having hooks  42  facing in different directions, while  FIG. 8  illustrates a structure which is built up from building elements having hooks  42  all facing in a single direction. 
         [0127]      FIG. 9  illustrates an example of a truss structure  86  which may built up from the modular blocks  10  described above. The modular blocks  10  are connected side-by side and vertically to form longitudinal members  88 , lateral members  90 , and vertical members  92 . Tapered blocks  94  are disposed at the upper ends of the vertical members  92  so that the uppermost longitudinal members  88  will be at the proper angle. 
         [0128]      FIG. 10  illustrates a ladder truss-type structure  96  having longitudinal members  98  and lateral members  100  which may be built up from modular blocks  10  described above. 
         [0129]      FIG. 11  illustrates a modular block  10  alongside additional modular blocks  110  and  112 . The modular blocks  110  and  112  are substantially identical in construction to the modular block  10 , and include hooks  114  and  116 , and locking recesses  118  and  120 , respectively. The modular blocks  110  and  112  differ from the modular block  10  in their size. This may vary from a size small enough to construct items such as electronic circuit boards, to as many as several feet on a side for elements for constructing buildings. 
         [0130]      FIG. 12  illustrates a modular block  122  which is designed to serve as an “adapter” for connection to different-sized modular blocks. The modular block  122  includes a single locking recess  124  on its lower side. Four “L”-shaped hooks  126  protrude from the upper surface of the modular block  122 . As shown in  FIG. 13 , this allows the modular block  122  to be connected to additional modular blocks  128  and  130  which are each one-quarter of the size of the modular block  122 . 
         [0131]      FIG. 14  illustrates another modular block  132  which is designed to serve as an “adapter” for connection to different-sized modular blocks. The modular block  132  includes a single “L”-shaped hook  134  protruding from its upper surface. Four locking recesses  136  are disposed on its lower side. As shown in  FIG. 15 , this allows the modular block  132  to be connected to additional modular blocks  138  which are each one-quarter of the size of the modular block  132 . 
         [0132]      FIGS. 16 and 17  illustrate an exemplary modular block  200  constructed according to the present invention. The modular block  200  is generally rectangular and includes a top surface  212 , a bottom surface  214 , and front, rear, left and right sidewalls  216 ,  218 ,  220 , and  222 , respectively. A plurality of generally cylindrical core passages  224  of various sizes pass through the modular block  200  from top to bottom. As shown in more detail in  FIG. 18 , each core passage  224  has an enlarged-diameter counterbore  226  formed at its upper end. As shown in more detail in  FIG. 19 , each core passage  224  has a plurality of semi-cylindrical key slots  228  formed around the periphery of its lower end. 
         [0133]      FIG. 20  illustrates an exemplary locking assembly  230 , which includes a core  232 , a locking rod  234 , one or more core keys  236 , and a rod key  238 , all of which are described in more detail below. The locking assembly  230  is received in one of the core passages  224  of a modular block  200  to enable the modular block  200  to be connected to other blocks, as shown in  FIG. 21 . The locking assembly  230  fits in the core passage  224  so that the upper end of the core  232  fits flush with the top surface  212  of the modular block  200 , as shown in  FIG. 22 , and the lower end of the core is flush with the bottom surface  214  of the modular block  200 , as shown in  FIG. 23 . 
         [0134]      FIGS. 24A through 24E  illustrate the assembly sequence of the locking assembly  230 . Referring to  FIG. 24A , the generally cylindrical core  232  has an enlarged boss  240  formed at its upper end which is sized and shaped to fit into the counterbore  226  of the core passage  224 . The core  232  has a through-bore  242  passing along its length. Approximately one-half of the through-bore  242  defines a series of alternating semi-cylindrical core grooves  244  and core lands  246 . The core grooves  244  have a first inner diameter, and the core lands  246  have a second inner diameter which is smaller than the first inner diameter. The remaining portion of the through-bore  242  is formed into a semi-cylindrical passage  247  having an inner diameter somewhat larger than the first inner diameter. 
         [0135]      FIG. 24B  illustrates a locking rod  234 . The locking rod  234  is generally cylindrical. Its outer surface defines a series of alternating cylindrical rod grooves  248  and rod lands  250 . The rod lands  250  have a first outer diameter which is approximately equal to the first inner diameter of the core grooves  244 , and the rod grooves  248  have a second outer diameter which is approximately equal to the second inner diameter of the core lands  246 . 
         [0136]      FIG. 24C  shows the locking rod  234  inserted into the core  232  and shifted laterally so that the rod lands  250  engage the core grooves  244 , and the rod grooves  250  engage the core lands  246 . Thus engaged, the locking rod  234  is prevented from moving axially relative to the core  232 . The locking rod  234  is inserted approximately halfway into the core  232 , so that a space will be left in the core for receiving another locking rod  234  in a manner described below. 
         [0137]      FIG. 24D  shows a rod key  238  about to be inserted into the core  232 . The rod key is an elongated, arcuate cross-section member with a laterally-extending lip  252  at its upper end. The outer wall  254  of the rod key  238  mates with the semi-cylindrical passage  247  of the core  232 , and the inner wall  256  of the rod key  238  mates with the rod lands  250 . When the rod key  238  is fully inserted into the core  232 , it prevents the locking rod  234  from shifting laterally and thus retains it in the core. 
         [0138]    A pair of oblong core keys  236 , best seen in  FIG. 26 , are disposed in core key openings  258  near the bottom end of the core  232  so that they can slide transversely to the long axis of the core  232 . The rod key  238  has opposed chamfers  260  at its bottom end (see  FIG. 25 ) which engage the core keys  236  and force them outwards as the rod key  238  is fully inserted into the core  232 . 
         [0139]    The locking assembly  230  is attached to a modular block  200  as follows. First, the core  232  with retracted core keys  236  is inserted into one of the core passages  224  of the modular block  200 . The locking rod  234  is then inserted into the through-bore  242  and shifted laterally as described above. The rod key  238  is then inserted into the core  232 , securing the locking rod  234  in place and also forcing the core keys  236  outward. As seen in  FIG. 23 , the core keys  236  engage the key slots  228  of the core passage  224 . The entire locking assembly  230  is thus securely attached to the modular block  200  and cannot be removed until the rod key  238  is removed. If desired, the materials, dimensions, and finish of the rod key  238  may be chosen to prevent its unintended removal from the core passage  224 . Furthermore, the rod key  238  may be provided with a means for assisting its removal, such as a fingernail slot or tool ledge (not shown). 
         [0140]      FIG. 27  shows a group of modular blocks  200 ,  200 ′, and  200 ″ connected together with a plurality of locking assemblies  230 . To assemble the modular blocks  200  and  200 ′ together, a locking assembly  230  is first installed into a core passage  224  so that approximately half of the locking rod  234  extends upward from the top surface  212  of the modular block  200  (see  FIG. 21 ). Then, a second core  232 ′ is inserted into the upper modular block  200 ′ without a locking rod  234  or rod key  238 . The locking rod (obscured in  FIG. 27 ) is inserted into the second core  232 ′ and shifted laterally so that its grooves and lands engage the grooves and lands of the second core  232 ′, similar to the manner described above with respect to  FIGS. 24A-24E . At this point, the modular blocks  200  and  200 ′ are assembled in an upper-and-lower touching relationship. If desired, a second locking rod  234 ′ may be inserted into the second core  232  and engaged with the grooves and lands thereof. A second rod key  238 ′ is then inserted into the second core  232  to lock both of the locking rods  234  and  234 ′ into place in the second core  232 ′ and prevent disassembly of the modular blocks  200  and  200 ′. 
         [0141]      FIG. 28  illustrates a connector plate  262  for being used to join two or more modular blocks  200  together side-by-side. The illustrated connector plate  262  is a flat member having a thickness sized to fit in a connector slot  264  formed in the periphery of a modular block  200  (see  FIG. 29 ). One or more connector pin holes  266  are formed through the connector plate  262 . In the illustrated example, the connector plate  262  is rectangular and has a two-dimensional array of connector pin holes  266  therein. 
         [0142]    As shown in  FIGS. 29 and 30 , some of the core passages  224  in the modular block  200  intersect the connector slots  264  thereof. A connector pin  268 , is sized to fit the core passage  224 . It may include an enlarged head  270  to prevent it from falling through the modular block  200 . 
         [0143]      FIG. 31  illustrates two modular blocks  200  and  200 ′ connected end-to-end. A connector plate  262  is inserted into connector slots  264  of each of the modular blocks  200  and  200 ′. A connector pin  268  is then inserted into core passages  224  of each of the modular blocks  200  and  200 ′, passing through the connector pin holes (obscured in  FIG. 31 ). This secures each of the modular blocks  200  and  200 ′ to the connector plate  262  and thus secures the modular blocks  200  and  200 ′ to each other, in both lateral and vertical directions. 
         [0144]      FIG. 32  illustrates another connector plate  272  for being used to join two or more modular blocks  200  together. The illustrated connector plate  272  is substantially similar to the connector plate  262  described above, differing only in the fact that it includes an array of relatively small-diameter connector pin holes  274 A, and another array of relatively larger connector pin holes  274 B are formed through the connector plate  272 . The connector plate  272  can be used to join modular blocks  200  having different-sized core passages  224 . As shown in  FIG. 33 , this allows the joining of relatively large modular blocks  200  and  200 ′ with a smaller modular block  200 ″. 
         [0145]      FIG. 34  illustrates a finish element  276 . The finish element  276  has a planar inner side  278  which is dimensioned and shaped to mate with a side wall of the modular block  200 . The inner side  278  includes one or more connector tabs  280  with connector pin holes  282  therein. The connector tabs  280  are positioned and sized to fit into the connector slots  264  of the modular block  200 . The finish element  276  has an exterior surface  284  with one or more sides or facets which are formed into a desired shape. In the illustrated example, the exterior surface  284  of the finish element  276  is shaped to form a portion of a cylinder. 
         [0146]      FIG. 35  illustrates a modular block  200  with several finish elements  276  attached thereto. They may be secured with connector pins (not shown) as described above, to form a solid structure with a cylindrical outer surface. The use of finish elements  276  allows the creation of structures that are modular, but which have arbitrary external shapes. 
         [0147]      FIG. 36  illustrates another type of connector plate  286 . The connector plate  286  is a flat member having a thickness sized to fit in a connector slot  264  formed in the periphery of a modular block  200 . An array of connector pin holes  288  are formed through the connector plate  286 . One or more cylindrical studs  290 , each having at least one cylindrical land  292  and one cylindrical groove  294 , are attached to the connector plate  286  and are extend parallel to the plane thereof. The installation of the connector plate  286  into a connector slot  264 , as shown in  FIG. 37 , gives the side of a modular block  200  the same connectivity as the top of the modular block  200 . More particularly, the studs  290  perform the same function as the locking rods  236  so that a modular block  200 ′ can be connected to the side of a modular block  200  (see  FIG. 38 ). 
         [0148]      FIG. 39  illustrates how various sizes of modular blocks  200 ,  200 ′,  200 ″,  200 ′″, and  200 ″″ may be connected to each other by using appropriately-sized locking assemblies  230  in the core passages  224 . Exemplary locking assemblies  230 ,  296 , and  298 , varying only in the size of their constituent components, are shown in  FIGS. 40 ,  41 , and  42 , respectively. The use of these different-sized locking assemblies  230 ,  296 , and  298  is enabled by the provision of different-sized core passages  224  in the modular blocks  200 . As shown in  FIG. 43 , these core passages  224  are laid out in a regular grid pattern within the modular block  200 . 
         [0149]      FIGS. 44 and 45  illustrate an example of how a complex structure, in this case a wheeled vehicle, can be built up from the components described above, including modular blocks  200 , locking assemblies  230 , finish elements  276 , connector plates  286 , and connector pins  268   
         [0150]    The modular blocks need not be square or rectangular. For example,  FIG. 46  illustrates a curved modular block  300 . The curved modular block  300  includes a top surface  312 , a bottom surface  314 , and front, rear, left and right sidewalls  316 ,  318 ,  320 , and  322 , respectively. The front and rear sidewalls  316  and  318  are curved into parallel arcs. A plurality of generally cylindrical core passages  224  pass through the curved modular block  300  from top to bottom. As shown in  FIGS. 47 and 48 , these curved modular blocks  300  can be used solely with other curved modular blocks  300 , or with rectangular modular blocks  200  to form structures with a desired shape. 
         [0151]      FIG. 49  illustrates a trapezoidal modular block  400 . The trapezoidal modular block  400  includes a top surface  412 , a bottom surface  414 , and front, rear, left and right sidewalls  416 ,  418 ,  420 , and  422 , respectively. The left and right sidewalls  420  and  422  are angled in opposite directions. A plurality of generally cylindrical core passages  224  pass through the curved modular block  300  from top to bottom. As shown in  FIG. 50 , these trapezoidal modular blocks  400  can be used with other trapezoidal modular blocks  400  to produce polygonal structures. 
         [0152]      FIG. 51  illustrates a lobed modular block  500  which includes a top surface  512 , a bottom surface  514 , and a continuous sidewall  516 . The sidewall  516  is curved into a shaped having a pinched-in “waist”  518  disposed between two cylindrical lobes  520 . A generally cylindrical core passage  224  passes through the lobed modular block  500  from top to bottom at the center of each lobe  520 . As shown in  FIGS. 52 and 53 , these lobed modular blocks  500  can be used to build up wall-like structures which can pivot about the locking rods  500  which hold them together. 
         [0153]    Any of the various shapes of modular blocks described above may be attached to any other shape as long as a core passage is available. An example of a structure built up from various block shapes is shown in  FIG. 54 . 
         [0154]      FIG. 55  illustrates another alternative modular block  600  constructed according to the present invention. The modular block  600  includes a top surface  610 , a bottom surface  612 , and front, rear, left and right sidewalls  614 ,  616 ,  618 , and  620 , respectively. An interior space  621  is defined along the central portion of the modular block  600 . As shown more clearly in  FIG. 56 , the modular block  600  is built up from two side members  622 A and  622 B, and one or more locking lugs  624 . Each of the side members  622  has an inner surface  626  and an outer surface  628 . The inner surface  626  of each side member  622  is generally planar and has a plurality of key grooves  623  formed therein. Because the inner surfaces  626  are identical, the side members  622  may be produced in large quantities by providing a workpiece with a flat surface, machining long, continuous grooves in the flat surface, and then cutting the workpiece into individual side members  622 . 
         [0155]    Each of the locking lugs  624  includes upper and lower notches  630 A and  630 B formed near its upper and lower ends. These notches  630  are positioned and sized so as to define “L” shaped upper and lower hooks  632 A and  632 B, respectively. The hooks  632  are sized to engage the notches  630 . 
         [0156]    Referring again to  FIG. 55 , the locking lugs  624  are assembled to the modular block  600  by clamping them between the side members  622 A and  622 B. It will be appreciated that the locking lug  624  may be assembled to the modular block  600  so that it points in any one of four directions. In  FIG. 55  the upper hooks  632 A of the locking lugs  624  extend towards the front endwall  614  of the modular block  600 , whereas in  FIG. 57 , the upper hooks  632 A′ of the locking lugs  624 ′ extend towards the right sidewall  620 ′ of the modular block  600 ′. The components may be secured together by adhesives, welding, thermal or sonic bonding, fasteners, or any other method that will create a unitary whole. The entire modular block  600  may also be formed as an integral component, for example by casting it from a mold. 
         [0157]    The modular block  600  and the locking lug  624  may be constructed of any material which is suited to the application for which the modular block  600  is to be used and which can be formed into the necessary dimensional features. For example, the modular block  600  may be used as a toy, a modeling element, or a light structural element, in which case it may be molded from a material such as plastic resin. The modular block  600  may also be used for heavier structural applications, in which case it may be formed from materials such as concrete, wood or engineered wood materials, pressed fiber, metals, or fiber composite materials. In the illustrated example, the modular block  600  includes an exterior fascia  601  intended to present a finished appearance. The fascia  601  may be formed as an integral part of the modular block  600 , or it may be added to the exterior of the modular block  600 , for example by building up a layer of mortar, joint compound, or the like, and applying an appropriate finish thereto. 
         [0158]      FIGS. 58 and 59  illustrate a key  634  to be used with the modular blocks  600 . The key  634  is an elongated member sized to fit into the interior space  621 . The key  634  has an upper end  636  with an alignment pin  638  protruding therefrom, and a lower end  640  with a complementary alignment hole  642  formed therein. The key  634  also includes at least one alignment rail  644  adapted to engage the key grooves  623 . In the illustrated example, the body of the key  634  is an “H” shaped cross-section, and the alignment rail  644  is formed by positioning a dowel between the uprights of the “H” section. This simplifies manufacture of the key  634 . 
         [0159]      FIGS. 60 and 61  illustrate an alternative key  646 . The key  646  is substantially similar to the key  634  and has an upper end  648  with an alignment pin  650  protruding therefrom, and a lower end  652  with a complementary alignment hole  654  formed therein. The key  646  also includes at least one alignment rail  656  adapted to engage the key grooves  623 . In the illustrated example, the body of the key  656  is generally rectangular, and the alignment rails  656  are formed by positioning dowels within slots  658  in the surface of the key  656 . 
         [0160]      FIGS. 62 and 63  illustrate how a plurality of modular blocks  600  may be assembled to form a larger structure. A first modular block identified as  600 A is positioned down over the locking lugs  624  of one or more other modular blocks  600 B,  600 C, and then shifted laterally so that the hooks  632  of the modular blocks  600 B and  600 C engage the notches (not visible in  FIG. 62 ) in the locking lugs  624  of the first modular block  600 A. This prevents the modular blocks  600 A,  600 B, and  600 C from being disconnected in a vertical direction. In creating the assembled structure, the orientation of the locking lugs  624  are preferable chosen so that the hooks  632  will all be facing in the same direction regardless of the orientation of the modular blocks  600 . For example, in  FIG. 62 , the modular block identified as  600 D has its hooks  632  facing perpendicular to its long axis. 
         [0161]    To secure the modular blocks  600  together, one or more keys are inserted into the central spaces  621 , with the alignment rails  644  engaging the key grooves  623  of both an upper modular block  600 A, and the modular block  600 C below it (see  FIG. 63 ). The engagement of the key  634  prevents lateral motion of the hook  632  relative to the notches  630 . A larger key  646  has multiple alignment rails  656  and therefore holds together two adjacent modular blocks  600 A and  600 E by engaging key grooves  623  in each of the blocks  600 A and  600 D. The dimensions, materials, and surface finish of the keys  634  and  646  may be selected to prevent unintended withdrawal. 
         [0162]    The modular blocks (for example items  10 ,  200 ,  300 ,  400 ,  500 , and  600 ) described above may be used for any type of construction which requires or would benefit from a modular characteristic. Several non-limiting examples of possible applications for theses blocks will now be set forth, without regard to a particular embodiment of the blocks themselves. Of course, the modular blocks can be used as toys or as small-scale modeling elements when produced in a proper size, say a few centimeters on a side. 
         [0163]    When produced in larger sizes, they may be used for residential or commercial building elements such as walls, roofs, floor, retaining walls, and windows (if made from transparent or translucent material). They may also be used to construct industrial structures such as factory floors, machine tool bases and machine bodies. 
         [0164]    The modular blocks can also be used to build marine structures such as piers, barges, underwater structures, and boat hulls. 
         [0165]    On a smaller scale, the modular blocks may be used to build up three-dimensional circuit cards, or if made of bio-compatible materials, they may be used to form three-dimensional frames for bone or organ tissue construction. If reduced to a sufficiently small scale, they can be used for nanostructures. 
         [0166]    The modular blocks may be formed out of armor material or projectile-resistant material, such as KEVLAR aramid fibers. These armored blocks can be used to form containers to ship military supplies. After the supplies are received at the destination, the containers can then be disassembled into modular blocks. These blocks can then be used to construct custom made protective shields for personnel or equipment. Shipping containers may also be made from more conventional construction materials and then used to ship food, water, or other supplies to disaster areas. After the supplies are received, the shipping containers may be disassembled into modular blocks and then used for low-cost buildings that can be quickly erected. 
         [0167]    The foregoing has described a modular block and a method of construction using such modular blocks. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.