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CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from U.S. provisional patent application 62/105,930 filed Jan. 21, 2015, the entirety of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Paving tiles which can be heated so as to melt any snow or ice deposited there on have been available for some time. These paving tiles generally include an electrical heating element imbedded within the tile, the heating element generally consisting of an elongated metal wire which heats up when electric current is passed through the wire. The electrical heating element generally heats up the surrounding portions of the tile, which in turn melts the ice or snow overlaying the tile. 
         [0003]    While electricity heated tiles of this sort are effective in maintaining an ice free walk way or path, the use of electrical heating elements comprised of metal wires has its drawbacks. 
         [0004]    Firstly, and most significantly, these type of heating elements results in uneven heating of the tile, resulting in spots where the tile is hotter than required and parts of tile which is cooler than required. As a result of this uneven heating, more electricity is utilized to ensure that all of snow is melted. 
         [0005]    A system which provides a more uniform heating of the tile would therefore provide a more effective and energy efficient de-icing paving tile and the present detailed invention outlines this by using electricity but, it can be utilized by using solar panels, batteries or other “renewable” energy. 
       SUMMARY OF THE PRESENT INVENTION 
       [0006]    In accordance with one aspect of the present invention, there is provided a ground tile for melting snow and ice. The ground tile includes a flat housing having upper and lower walls and opposite sides, the upper and lower walls and opposite sides defining an interior space. The ground tile also includes first and second electrodes disposed in the interior space, the first and second electrodes being spaced apart accordingly from one another. The interior space is filled with an aqueous glycol solution, the aqueous glycol solution being configured to heat up by electric resistance when an AC current is applied between the first and the second electrodes. 
         [0007]    With the foregoing in view, and other advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the preferred typical embodiment of the principles of the present invention. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an isometric exploded view of four de-icing paving tiles made in accordance with the present invention. 
           [0009]      FIG. 2  is isometric view of the shell assembled of one of the de-icing paving tiles made in accordance with the present invention showing the internal electrodes. 
           [0010]      FIG. 3  is an isometric view of the electrodes shown in  FIG. 2 . 
           [0011]      FIG. 4  is an exploded view of the shell made of two halves shown in  FIG. 2 . 
           [0012]      FIG. 5  is a cross sectional view of a tile made in accordance with the present invention, showing the lock connector. 
           [0013]      FIG. 6  is an exploded view of a single tile showing three lock connectors. 
           [0014]      FIG. 7  is an exploded view and sections of the lock connector assembled with disk springs and “O” rings. 
           [0015]      FIG. 8  is a bottom view of four tiles made in accordance with the present invention showing the means of interlocking the tiles together and lock and unlock positions. 
           [0016]      FIG. 9  is an exploded view of the shell and ground sheath made in accordance with the present invention. 
           [0017]      FIG. 10  shows four tiles and a section though the lock and labyrinth made according to the present invention. 
       
    
    
       [0018]    In the drawings like characters of reference indicate corresponding parts in the different figures. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Referring firstly to  FIG. 1 , an array of heating tiles, shown generally as one, can be used to pave an area of ground. The array consists of a plurality of de-icing tiles  10 , each being a square tile having four opposite sides which are configured to interlock with an abutting side on an adjacent tile. A plurality of convex profiles  12  are formed in each top surface of the tile to avoid slipping, any size or shape tile could be used, but in present invention is chosen a square tile. 
         [0020]    On a complete set of tiles to cover the required ground, driveway or walkway and steps, the sides and the ends are protected with a plurality of the kick bars,  104 ,  105  and  106 , shown on  FIG. 1 . 
         [0021]    Each de-icing tile consists of a shell  11  which is over molded with a tough and resilient polymer. At best seen in  FIGS. 2 and 4 , the core portion of each tile consists of a bottom half of the shell  14  containing an interior  16  defined by top half shell wall  18  containing an interior  17 , opposite sides  22  and  24  and opposite sides  26  and  28 . The  14  and  18  shell halves could be identical, as shown, or otherwise. 
         [0022]    Electrodes  40  and  36  are positioned in the interior space between  16  and  17  interior of each half shell. Electrode  40  is identical with electrode  36 , or otherwise and rotated 180 degrees to each other inside adjacent sides  22 ,  24 ,  26  and  28 . Fittings  44  and  46  are positioned on the side  28  and provide a means for filling interior  16  and  17  with aqueous and glycol and plugged with  100 . Electrode connector  50  is coupled to electrode  36  and electrode connector tab  52  is coupled to electrode  40 , both tabs project outside middle where the shell splits. 
         [0023]    Electrode connector  102  is coupled to electrode  36  and electrode connector tab  101  is coupled to electrode  40 , both tabs project outside middle where the shell splits. 
         [0024]      FIG. 2  shows a water tight shell and a plurality of support columns  48 , part of each half of the shell and sealed together and act to strengthen the structure from external load. 
         [0025]    Electrode connectors  50  and  52  are for input AC and  101  and  102  are receiving power through the electrode and a good conductivity wire  120  and  121 ,  FIG. 3 , to avoid resistivity of the electrodes, to power the next tile. 
         [0026]    Electrode  40  has an external wire frame  120  which is connected to tab  52  one end and to tab  101  at the other end. Electrode  36  has external wire frame  121  which is connected to tab  50  at one end and tab  102  at the other end. Convolutions  128 ,  124  and  123  are extensions of electrode  40  (see  FIG. 3 ). Convolutions  127 ,  125  and  126  are extensions of electrode  36  (see  FIG. 3 ). 
         [0027]    Interior  16  and  17  is filled with electrically conductive aqueous and glycol solution, or similar solute. 
         [0028]    The aqueous and glycol solution must contain a sufficient concentration of electrolytic to avoid freezing solute to permit the solution to carry an AC between electrodes  36  and  40 . Referring now to  FIG. 3 , electrodes  36  and  40  have convolutions as described above. The convolutions of electrode  36  are interlaced with the convolutions of electrode  40  such that a substantially fixed distance  56  is maintained between all portions of electrodes  36  and  40 . Because of the distance  56 , electrical current is conducted between portions  124  and  126 ,  124  and  125 , between  123  and  125 , between  126  and  40 ,  125  and  128 ,  126  and  128 ,  123  and  127 , and between  123  and  36 , between  127  and  40  and between  128  and  36 , essentially the entire interior of the tile is electrically heated in an uniform fashion. Since the electrodes are placed at distance  56 , the electrical current passing through the aqueous and glycol solution is substantially uniform through interior  16  and  17 . The aqueous and glycol solution essentially acts as an electrical resistance heating element and heats up as the electrical current flows through the solution. This results in substantially uniform heating of the entire core.  FIG. 4  shows an exploded view of the shell  11 . 
         [0029]    The electrodes  36  and  40  have insulator blocks  127 ,  128 ,  129  and  130 , in the areas where they are very close, mainly to avoid overheating because of proximity of the other electrode. 
         [0030]    The concentration of aqueous and glycol solution filling the interior of the tile core is important. The concentration should be selected to insure that there is sufficient electrical conductivity to heat the solution at an appropriate rate to ensure melting of ice or snow overlaying the tile (not shown). Also, to ensure that the aqueous and glycol solution in the tile does not freeze, the aqueous and glycol solution should be sufficiently high. It has been discovered that approximately 30% of glycol in aqueous solution is sufficient to keep the solution liquid in subzero winter weather, while at the same time being sufficiently conductive to provide sufficient heat to melt snow and ice when current is applied. 
         [0031]      FIG. 5  shows the lock and unlock positions. The side where the locks  200  ( FIG. 7 ) are placed is used to feed the tile from a busbar ( FIG. 1 ) and also to power the next tiles on the row. The assembly will require to place the tile with electrode connectors with lock assembly  200  unlocked over connector tabs  101  and  102  and lock them to secure the AC flow. 
         [0032]    As mentioned above, the tile consists of inner shell  11  and an outer sheathing  70 ,  FIG. 6 , which is over-molded onto the shell. The shell is preferably formed as an upper and lower shell half which is then brought together and fused (sealed) after the insertion of the electrodes  36  and  40 , wire  120  and  121  and electrode connectors  50 ,  52  and  101  and  102  and fittings  44  and  46 . 
         [0033]    Electrode connectors  50 ,  52 ,  101  and  102  and fittings  44  and  46  will project out of inner shell  11  and through sheathing  70  to make electrical circuit between two or more adjacent tiles possible. Also, fittings  44  and  46  will project out of inner shell  11  and through non-metal sheathing  70  to be able to fill up the interior of the tile with aqueous and glycol solution and plugged with  100 ,  FIG. 2 . 
         [0034]    As mentioned above, support columns  48  are part of each half of the shell and sealed together to take the external loads, such as cars. The columns  48  help to support the tile and prevent the upper and lower walls from collapsing when pressure is applied to the tile. 
         [0035]    The three lock assemblies  200 ,  FIGS. 5, 6 and 7 , consists of a barrel  201 , “T” lock shaft  202  and to secure electrical contact, the disk springs  203  and  204  will tighten the electrode connector tabs  50  with  102  and  52  with  101 . The tapered portion  207  of “T” lock  202  will get engaged on the bottom portion of the connectors  101 ,  102  and  361  and lock. The third lock assembly  200  will be used to secure the ground contact between ground bars  361  on both ends and the metal sheath  360 , top and bottom,  FIG. 9 . 
         [0036]    Both metal sheaths  360 , top and bottom, are covering the shell  11  and kept together with “U” metal brackets  362  and the metal ground bar on top  361 ,  FIG. 9  and the assembly of  360 ,  361  and  362 , will form a metal sheath and will be enveloped into non-metal sheath  70 . 
         [0037]    The lock assembly  200  is made of non-conducting material. 
         [0038]    To rotate barrel +/−90 degrees  201  and “T” lock shaft  202  together, a slot  205  is provided. To remove the tile when the lock is in unlock position a circular profile  206  is provided,  FIG. 7 , using a tool (not shown). 
         [0039]    To prevent water to reach the electrode connectors  50 ,  52 ,  101  and  102 , there are two “O” ring seals  350  mounted on the barrel  201  grooves and when mounted will seal into the holes of sheath  70 ,  FIGS. 6, 7 and 10 . Also, a labyrinth  370  is provided on the barrel  201 ,  FIGS. 5, 7 and 10  which will get engaged with the labyrinth in sheath  70 . 
         [0040]    The lock assembly  200  is placed first in the round holes of the electrode connector tabs  50 ,  52  and  361  as follows: the “T” lock shaft  202 , disk springs  203  and  204  and “O” rings seals  350  on a complete tile  300 ,  FIG. 6 , and barrel  201  is pressed over “T” lock shaft  202  and the barbed profile  208  inside  201  and outside  202  will get engaged and secured,  FIGS. 5 and 6 . The slot  212  inside “T” lock shaft will allow the shaft to collapse at the insertion. The barrel tab  209  will limit the rotation of locking assembly in the tile against  210  to lock and  211  to unlock. 
         [0041]    At the assembly of tiles, the “T” lock shaft will be in the unlock position and will go on top of the busbar or next tile and insert into the slots placed into electrode connector tab  101 ,  102  and  361  and lock. 
         [0042]    To prevent water to reach the electrode connectors through the contact profile  363  on the top side of the tiles,  FIG. 10  and through the contact profile  364  on the bottom of the tile,  FIGS. 5, 8 and 10 , a labyrinth  351  and  352  is provided, in accordance with present invention. 
         [0043]    The present invention has many advantages over the prior art. In particular, the use of the aqueous and glycol solution results in a very even heating of the tile. Also, the concentration of the aqueous and glycol solution can be selected to adjust the heat output of the tile without having to change the electrodes. Adjusting the concentration of the glycol in the solution also helps to prevent freezing of the solution in situations where the temperature of the environment will be exceptionally low. The tiles can be laid out in multiple configurations to accommodate the shape of the ground. The location of the electrode tabs can be selected to be on either the right or left sides to electrically connect adjacent tiles. The shape of the tiles need not be square and can be in any appropriate shape as required for the specific layout. 
         [0044]    The tiles, either individually or in groups can be coupled to an external control module having a PLC (or similar) controller coupled to temperature and snow precipitation sensors. The control module can be preprogrammed to optimize the consumption of AC current dependant on the outside temperature and whether or not it is snowing, decreasing the current used when the temperature is high or where there is no snow falling. The external metal sheathing of the tiles can also be coupled to the ground circuit of the control module and the control module can be further configured to shut off the AC current in the event of a leak in the tiles or water infiltration in the external electrodes coupling one tile to another. 
         [0045]    As the tiles are preferably used to pave driveways, walkways and steps, illumination may be provided in the tiles, such as the use of fluorescent or luminous barrels  201  (or other components).

Summary:
Herein is disclosed a ground tile for melting snow and ice. The ground tile includes a flat housing having upper and lower walls and opposite sides, the upper and lower walls and opposite sides defining an interior space. The ground tile also includes first and second electrodes disposed in the interior space, the first and second electrodes being spaced apart accordingly from one another. The interior space is filled with an aqueous glycol solution, the aqueous glycol solution being configured to heat up by electric resistance when an AC current is applied between the first and the second electrodes.