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BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to an expansion joint for modular flooring. More particularly, the invention relates to the use of a slidable member which is interspersed between tiles of plastic modular flooring, which is adapted to permit relative movement of subsections of the modular flooring during installation. 
         [0003]    2. Description of the Prior Art 
         [0004]    Modular flooring of various designs has been utilized for a significant period of time to provide a temporary walking or other rigid surface in areas where permanent flooring is either not necessary or prohibitively expensive. More particularly, modular flooring is primarily utilized in commercial settings where a floor is temporarily needed, such as on a grass or artificial turf surface as well as in industrial or construction areas. With respect to industrial or construction areas, temporary flooring may be utilized to provide walkways, driveways, parking areas or other rigid surfaces for the transport of materials, vehicles, storage or mounting of equipment, or simply as a walking or standing surface for people. The modular nature of such flooring is utilized to adapt the flooring to the particular topographic or geographic needs of the particular site and to also allow for the efficient storage and transport of the modular flooring. In addition, the use of relatively small modular floor tiles permits repairs and disposal of broken floor sections with relative ease. 
         [0005]    In operation, the selection of the particular floor tile and its characteristics are primarily based upon the amount of load expected to be exerted on the modular flooring system, as well as the relative support characteristics of the underlying substrate be it concrete, artificial turf, grass, dirt, or the like. Once the particular floor tile is selected, a number of modular tiles typically having some type of interlock mechanism are applied to the surface and are generally laid in a sequential pattern, permitting the selective interlock of the various tiles and the placement of those tiles in a preplanned topographic design intended to permit the movement of materials, people, vehicles or the storage of the same in appropriate locations. The modular floor tiles are themselves typically constructed of plastic or other polymeric materials which permit relatively high-strength sections having relatively low weight, providing ease of storage and portability. One particular shortcoming of plastic and polymeric materials is the coefficient of thermal expansion, which is relatively high in practice. Changes in temperature of the underlying substrate material, as well as the ambient air proximate to the modular floor system cause relatively significant changes in dimensionality of the floor tiles. While the dimensional changes in each individual tile are relatively small, over a large area with hundreds, perhaps thousands, of interlocked tiles, the cumulative expansion or contraction of the entire flooring system causes significant problems with respect to maintenance of the floor, as well as the safety of the users. 
         [0006]    In practice, this expansion of the modular flooring system causes buckling, shifting and cracking of the floor tiles, as well as providing a tripping hazard for persons walking on the floor and potentially causing dangerous conditions which could cause vehicles to be diverted from their intended course over the surface of the modular floor. 
         [0007]    Other limitations of the modular flooring system include the requirement that the floor be laid sequentially in order to ensure the appropriate alignment and interlocking of the modular tiles. In practice, this means that a tile floor must be laid from one location and expanding outwardly from that location on an interlocking basis and cannot be laid in discontinuance sections. Furthermore, the alignment and location of each tile is very important because small deviations from the preplanned alignment of the tiles over the course of longer distances will result in a floor being significantly displaced from its preplanned location. This results in significant delays and costs associated with picking up and relaying the various floor tiles once the misalignment has been discovery after a significant number of tiles have been laid. 
         [0008]    There remains a need, therefore, in the art of modular flooring, for an adjustable or displaceable tile which may be inserted at various locations in a modular floor system to absorb the expansion of the floor tiles in atmospheric conditions which cause expansion and contraction of the modular floor or subsections thereof. Additionally, there remains a need in the art for an adjustable tile which may be inserted in order to maintain the alignment and appropriate location of sections for the entirety of the modular floor over its length. 
       SUMMARY OF THE INVENTION 
       [0009]    A modular floor expansion joint is disclosed which provides both a means for absorbing the expansion of adjoining floor tiles and permitting the various expanding or contracting sections of the modular floor to remain flat on the substrate, as well as to permit a minimal amount of misalignment in the application of the floor tiles to a substrate by providing an adjustment means for subsections of the floor. In practice, this permits the insertion of the expansion joint tiles at locations where a misalignment has occurred and been discovered. Once a significant portion of the modular floor has been laid, the adjustability of the modular floor tile expansion joint permits the realignment of neighboring sections of adjoined modular floor tiles to the preplanned topographic location. The expansion joint also prevents the floor to be laid in discontinuous sections which may be moderately misaligned and joined by the adjustable expansion tile. 
         [0010]    The expansion joint floor tile is provided as a generally slidably, adjustable multi-section tile and is equipped with appropriately sized and shaped interlocking devices such that it may be mounted within a floor tile matrix as any location, replacing one or a series of modular floor tiles without disrupting the alignment pattern of such a modular floor tile system. The slidable multi-part tile is generally adapted to expand or contract in one dimension, but may be laid in an aligned pattern, such that the axes of expansion are aligned linearly or in a parallel fashion, or may be laid in a parquet style to permit multi-dimensional expansion or contraction of the floor as well. 
         [0011]    The multi-section expansion joint is generally provided in the preferred embodiment with two interlocking sections, one of which slides and is located within a locating sleeve of the other. An indented or undercut portion of a first member is adapted to be inserted and be slidably displaceable within the sleeve provided in the second member. The two members are adapted to be either temporarily or permanently joined through any particular means well-known to those skilled in the art in the preferred embodiments. A protrusion is provided on one member to be interfaced with a slot on the second member, such that the protrusion may be inserted into the slot and then laterally displaced along the longitudinal axis of the slot. A variety of locating means may be utilized to both use the insertion of the members together, as well as to maintain the geometric alignment of the two members during the sliding process in an axial fashion. 
         [0012]    In order to maintain the compressive strength of the floor tile system, a series of support webs, or other reinforcing means may be applied to the expansion joint, such that it matches the adjoining floor tiles in height and other critical dimensions, as well as its ability to support the intended load. Lastly, for both cosmetic and functional reasons, the exterior surface of the floor tile may be provided with both decorative embellishments, as well as various ventilation or other functional surface features to permit or prevent the passage of moisture facilitating the passage of persons and vehicles thereover. This is utilized to increase the frictional characteristics of the top surface so that a slippery condition is not provided on the top surface when mounted within the modular flooring system. 
         [0013]    These and other advantages of the expansion joint provided herein will be more fully understood with reference to the appended drawings and the description of the preferred embodiments herein. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a top plan view of a first embodiment of a modular flooring system, including both prior art floor tiles and a first embodiment of the expansion joint tile. 
           [0015]      FIG. 2  is a top plan view of a second embodiment of a modular flooring system, including both prior art floor tiles and a second embodiment of the expansion joint tile. 
           [0016]      FIG. 3  is a top plan view of the embodiment illustrated in  FIG. 1  with the expansion joint in an extended orientation. 
           [0017]      FIG. 4  is a top plan view of the embodiment illustrated in  FIG. 2  with the expansion joint in an extended orientation. 
           [0018]      FIG. 5  is an isometric exploded view of a first embodiment of the expansion joint as seen from the top. 
           [0019]      FIG. 6  is an isometric exploded view of a first embodiment of the expansion joint as seen from the bottom. 
           [0020]      FIG. 7  is an isometric view of the top of the second embodiment of the expansion joint in the closed position. 
           [0021]      FIG. 8  is an isometric view of the second embodiment of expansion joint as viewed from the bottom in the open position. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    Referring to  FIG. 1 , a matrix of modular floor tiles is illustrated having a number of component parts. A first embodiment is depicted in  FIG. 1  while a second embodiment is depicted in  FIG. 2 . Referring now to  FIGS. 1 and 2 , modular floor tiles of the prior art are identified as floor tiles  1 . The first embodiment being identified as embodiment  1   a  and the second embodiment being  1   b.  References herein to elements common to both embodiments will identify those same elements by reference numeral where the embodiments differ. The further identifiers, a and b will be used respectively, modular floor tiles  1  are provided in an interlocking matrix  10  which extends in two dimensions in accordance with a preset topographic plan. As discussed previously, the topographic plan is typically directed towards the conveyance or support of equipment, vehicles, personnel and the like and is adapted to conform to the topographic or geographic features of the substrate surface, such as grass, dirt, artificial turf or the like, modular floor tiles  1  are typically constructed of plastic material and are preferably polypropylene, polyethylene, polystyrene, acrylonitrile butadiene styrene, and polyvinylchloride. Differences between the first and second embodiments, as well as other embodiments not illustrated herein, but within the scope of knowledge of one skilled in the art, would include changes in dimensionality, including height, width and length, as well as surface features. Although not specifically illustrated, the invention contemplates the use of three-dimensional surface features to reduce slippage as well as ventilation holes  25  illustrated in  FIG. 1  of the first embodiment. Other applications may include three-dimensional surface features for the conveyance of moisture, as well as for decorative purposes. One significant feature of modular floor tile  1  when assembled into a matrix  10  is the desire to reduce any misalignment or unintentional three-dimensional surface changes in the top surface  27  of the floor tiles. Any height misalignment or departure of the floor tile from uniform engagement with the substrate may result in an unsafe condition presented by improper interlocking of modular floor tiles  1  or buckling of the entirety or portions of the matrix  10  surface causing an uneven walking or vehicular traffic surface. 
         [0023]    In application, modular floor tiles  1  are typically provided with a series of locking tabs  15 , which extend outwardly from the perimeter of each tile. In accordance with the specific design features of each embodiment, the locking tabs may be of any size or shape appropriate to support the weight and load requirements of the tile. Furthermore, the number of distribution of the locking tabs  15  are determined by the physical conditions of the likely substrate, as well as the load requirements mentioned previously. Locking receptacles  20  are also located on the perimeter of each of the modular floor tiles  1  for receiving and restraining locking tabs  15  and are disposed geometrically in accordance with the corresponding location of locking tabs  15  on adjacent floor tiles  1 . It will thus be appreciated that the sequential application of modular floor tiles  1  will include the serial interlocking of adjacent floor tiles in a matter to extend matrix  10  in two dimensions. In accordance with the preferred embodiments herein, an expansion tile  30  is provided, which may be interspersed at various frequencies within matrix  10  as a substitute for modular floor tiles  1 . Expansion tiles  30  may be aligned linearly on an axial geometry or as illustrated in  FIGS. 1 and 2 . The linear geometry in which the adjacent expansion tiles  30  are adapted and aligned, such that the direction of their expandability is similarly aligned to provide an extended section of expandability within matrix  10 , as will be more fully understood with references to  FIGS. 3 and 4 . As illustrated in  FIGS. 1 and 2 , expansion tiles  30  are shown in a closed position, which is one of three likely positions provided for expansion tiles  30  being fully closed, fully open and then intermediate position. The mounting and insertion of expansion tiles  30  is dependent upon the anticipated changes in weather conditions, as well as changes in substrate and the likely need for adapting matrix  10  during the installation period of modular floor tiles  1 . It will be appreciated by those skilled in the art that to the extent that the likely temperature change of the ambient air and adjacent surface or substrate is likely to increase then the expansion tile  30  would be laid in an open position or an intermediate position whereas, if it is likely that the temperature will substantially decrease, then the expansion tile  30  would be laid in the closed position, or an intermediate position, as it is well-known to those skilled in the art that the plastic material expands with increasing temperature. The insertion of expansion tiles  30  are specifically intended to permit the relative movement of sections of matrix  10  relative to each other during the expansion and contraction of modular floor tiles  1  within matrix  10 , without creating any surface irregularities or misalignments of modular floor tiles  1  within matrix  10 . Furthermore, it is intended that the adjustability of expansion tiles  30  will reduce damage to modular floor tiles  1 , which might occur as a consequence of the relative rigidity of modular floor tiles  1  within respect to the increasing or decreasing lateral forces on the tile within the matrix because of changing temperatures. 
         [0024]    Referring now to  FIGS. 3 and 4 , expansion tile  30  is shown in an extended orientation or open orientation which pen-nits the exposure of the interior of expansion tile  30 . Expansion tile  30  is provided with a top surface  35  and the expansion joint itself is provided with expansion joint top surface  40 , as will be more fully illustrated with respect to  FIGS. 5 ,  6 ,  7  and  8 . The design of expansion tile  30  is specifically intended to provide a relatively flat surface within the tolerances necessary to reduce any hazard of tripping or other negative consequences of an uneven floor surface. Even in the extended or open mode identified in  FIGS. 3 and 4 , expansion tile  30  provides a relatively flat surface over the extent of matrix  10  with significant minimization of surface irregularities or discontinuous portions. 
         [0025]    Referring now to  FIGS. 5 and 6 , the specific features unique to the first embodiment will be illustrated. However, unless specifically identified as a separate features, corresponding parts having identical reference numerals between the first and second embodiments illustrated in  FIGS. 5 and 6 , and  7  and  8 , respectively, shall be considered applicable to both embodiments. Referring now particularly to  FIGS. 5 and 6 , expansion tile  30   a  is provided with an expansion tile upper surface  35   a , locking tabs  15  are provided in a generally “T” shaped orientation, having a roughly cylindrical members extending outwardly therefrom for the rotational insert in corresponding locking receptacles  20 , where locking tab  15  may be tipped in at an angle to the substrate surface and inserted within locking receptacle  20  and rotated angularly about locking tab  15  to permit the secure interconnection between adjacent expansion tiles  30  or separate ones of expansion tiles  30  and modular floor tiles  1 . 
         [0026]    Expansion tile  30   a  is generally provided with two separable subsections, being the support section  53  and the sleeve section  54 . In general operations, support section  53  is inserted into and slidably engages sleeve section  54 . Support section  53  is provided with an expansion joint support  50  in the general format of an extending armature which is partially defined by undercut track  70  and expansion joint top surface  40   a . The combination of these two elements form expansion joint support  50 , which is an adaption for slidable engagement and insertion into sleeve section  54 . Expansion joint support  50  is provided with expansion slots  45  on expansion joint top surface thereof, which are adapted to receive and slidably restrain locking pins  85 , as will be further discussed with respect to  FIG. 6 . A flexible spring  65  is provided at the distal end of expansion joint support  50  for engagement with an inner surface of sleeve section  54  and which biases expansion tile  30   a  from a closed position to an intermediate open position. 
         [0027]    Sleeve section  54  is provided with expansion joint sleeve  55 , which is defined as an overhanging section of sleeve section  54 , adapted to receive expansion joint support  50  within expansion joint receiver  60 , defining an open space into which expansion joint support  50  is inserted and received. Essentially, expansion joint receiver  60  is formed by an overhanging section of expansion tile top surface  35   a  and the side walls of sleeve section  54 . Referring now to  FIG. 6 , the undersurface of expansion tile  30   a  is illustrated, having a series of support web members  80  which may be arranged and disposed in any particular pattern, which provides dimensional and load support for top surface  35   a . The bottom surface  75  of expansion tile  30   a  is formed as the underside of the plastic sheeting material forming top surface  35   a  and ventilation holes  25  extend therethrough to provide fluid and/or air communication between expansion joint bottom surface  75  and top surface  35   a . Expansion joint sleeve bottom surface  76  is provided with at least one, and preferably a series of locking pins  85 , which are typically extending outwardly from expansion joint sleeve bottom surface  76  and are provided with any type of restraining geometry known to those skilled in the art and most preferably at least one hook interface to be inserted within slots  45  of support section  53  for a semi-permanent engagement. It is specifically intended that having been inserted in slots  45 , locking pins  85  are either not removable or removable only with intent and some degree of difficulty. As assembled, expansion tile  35   a  permits the slidable engagement of support section  53  and sleeve section  54  through the displacement of locking pins  85  within slots  45  and the extremes of such travel are defined by the length of slot  45  and the number and location of locking pins  85 . 
         [0028]    Referring flow to  FIGS. 7 and 8 , the second embodiment is illustrative of expansion tile  30   b  having a top surface  35   b  and an insert section  57  and receiver section  56 . While not functionally identical to support section  53  and sleeve section  54 , insert section  57  and receiver section  56  perform roughly analogous functions. As with the first embodiment, expansion joint bottom surface  75  is provided with at least one or a series of support webs  80 , which provides structural support for top surface  35   b . Insert section  57  is generally provided with an expansion joint  50 , which is formed primarily by undercut track  70  and is adapted to be inserted in slidably received by expansion joint receiver  60  within receiver section  56 . A series of expansion slots  45  are provided for receiving and restraining locking pins  85 , which are affixed to the bottom surface  75  of receiver section  56 . As with the first embodiment, these locking pins may be provided with any particular arrangement of protrusions to permit the engagement and restraint of locking pins  85  within slots  45 . The second embodiment, however, provides an insertion hole  62  within expansion slot  45  for the easy insertion and removal of locking pins  85  within expansion slot  45 . As with the first embodiment, the locking pins  85  define the length and extent of travel of the slidable engagement between receiver section  56  and insert section  57 . Additional lateral support for the sliding engagement of receiver section  56  and insert section  57  is provided by locating slots  90  provided in insert section  57  and locating tabs  95  provided on the bottom surface  75  of receiver section  56 . Locating tabs  95  are arranged perpendicularly to bottom surface  75  and are adapted for the slidable insertion within locating slots  90 . 
         [0029]    Finally, one preferred embodiment of the invention has been described hereinabove and those of ordinary skill in the art will recognize that this embodiment may be modified and altered without departing from the central spirit and scope of the invention. Thus, the embodiment described hereinabove is to be considered in all respects as illustrative and not restrictive. The scope of the invention being indicated by the appended claims rather than the foregoing descriptions and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced herein.

Summary:
An expansion joint for a modular flooring system in disclosed, which includes the slidable engagement of two subsections of the expansion joint. The expansion joint is sized such that it is equivalent in overall dimension to the intended adjacent modular floor tiles of which it will form a part within a matrix of such interlocked modular floor tiles. The expansion joint is provided with at least one slot on one module, corresponding to at least one locking pin on the other module. The slot receives and restrains the locking pin and permits the slidable engagement along the longitudinal axes thereof.