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FIELD OF THE INVENTION 
   The present invention relates to an improved base for a large, commercial rooftop air conditioning (A/C) unit. More specifically, it relates to a new paneled floor system that serves as the base for a large rooftop A/C unit that is adaptable for installation onto an existing building roof curb. This design allows for ease in retrofitting new energy efficient A/C units onto older buildings. 
   BACKGROUND 
   Commercial rooftop A/C units gained huge popularity and growth in the 1980&#39;s. The technology of that time only allowed for a 20 year life span. This will necessitate the replacement of many of the aging, larger commercial rooftop A/C units presently in use in the next decade. This replacement operation can be substantially simplified with the present invention. 
   Commercial buildings generally have flat roofs upon which the building A/C units are mounted. A continuous curb, or rectangular frame enclosure is mounted on the roof, around a roof opening, so as to form a small dam. The curb is higher than the rooftop water level preventing water in leakage through the roof opening. This curb is integrated into the roofing system and roofing materials of the building, and is custom built for the specific dimensions of the A/C unit to be installed. The A/C unit rests on top of the curb and is mounted to the curb. New A/C units are generally not compatible with the older curbs, and while curb adapters can be designed, built and installed, these add an additional height to the overall unit. This can add additional roof weight, increase the wind loads and destroy the aesthetics of the original layout as most existing units are located out of line of sight or are placed behind visual screening apparatus. 
   The present invention uses a set of corrugated floor panels that interlock to form a base or floor that has a smooth, planar bottom surface. Since the major manufactures of rooftop A/C units make these units with similar dimensions, the floor panels can be made slightly longer than largest A/C unit&#39;s width, so that the base&#39;s bottom surface can rest directly on a plethora of differently sized curbs. There will be a minimal amount of cantilever over the existing curbs, but in this way, no curb adapter is necessary, and further, there is no need for various bases in differing lengths as this may be adjusted with the number of interlocking panels. 
   Such an innovative A/C base as the present invention provides, overcomes the pitfalls of the prior art and is a simple solution that enables the ease of an A/C unit retrofit by any manufacturer atop of any other manufacturer&#39;s rooftop curb. 
   SUMMARY OF THE INVENTION 
   The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a simple, length adjustable rooftop A/C base for retrofitting new A/C units onto existing rooftop curbs. 
   It has many of the advantages mentioned heretofore and many novel features that result in a new, A/C unit base design which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art, either alone or in any combination thereof. 
   In accordance with the invention, an object of the present invention is to provide an improved rooftop A/C base that will eliminate the need for a curb adapter. 
   It is a further object of this invention to provide an improved rooftop A/C base that is simple and economical to construct. 
   It is a final object of the present invention to provide an improved rooftop A/C base design that will minimize the height, weight and wind load of a retrofitted rooftop commercial A/C unit. 
   The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. Other objects, features and aspects of the present invention are discussed in greater detail below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective cross section of a conventional A/C rooftop unit curb; 
       FIG. 2  is a cross section of a conventional A/C rooftop unit base mounted onto a curb; 
       FIG. 3  is an end cross sectional view of the floor panel top plate; 
       FIG. 4  is an end cross sectional view of the floor panel bottom plate; 
       FIG. 5  is an end cross sectional view of two assembled floor panels that have been connected and filled with foam insulation; 
       FIG. 6  is a perspective view of three connected floor panels before foam insulation; 
       FIG. 7  is an end cross sectional view of a modified base atop a curb narrower than the rooftop A/C unit; 
       FIG. 8  is an end cross sectional view of a base atop a curb of the maximum width to accommodate the rooftop A/C unit; 
       FIG. 9  is a side cross sectional view of a base atop a curb unit shorter than the length of the rooftop A/C unit; 
       FIG. 10  is a side cross sectional view of a base atop a curb unit of the maximum length to accommodate the rooftop A/C unit; 
       FIG. 11  is an end cross sectional view of the base and first wall panel clip; 
       FIG. 12  is an end cross sectional view of the base and second wall panel clip; and 
       FIG. 13  is a cross sectional view of the base and first wall panel clip formed by extrusion. 
   

   DETAILED DESCRIPTION 
   The present invention relates to an improved rooftop A/C base, utilizing a series of interconnectable, corrugated floor panels that have a smooth, planar bottom surface that are adapted for installation atop of most existing rooftop A/C curbs. 
   There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. 
   In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. 
   The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
   The design of a standard commercial rooftop A/C unit base is well known in the industry. It is the unique configuration and design of such a base that is the subject of this invention. 
   Looking at  FIG. 1 , a conventional curb  2  can be seen atop a flat roof  4 . Curb  2  is a linear steel channel  6  that has been mechanically affixed to the roof  4  by some form of mechanical fastener  8  such as a bolt or screw. The top lip  10  of the channel has a furring strip mechanically affixed to its underside. The furring strip  12  serves as a wooden surface to accommodate conventional building methods (such as nailing or stapling) for affixing roofing  14 , water barrier materials or the such. Steel formed or structurally bent channels are used because they are strong, lightweight and can be made to offer a broad support surface on their top lip  10  for the A/C unit to rest upon. 
   Looking at  FIG. 2 , a conventional A/C rooftop unit base  14  is illustrated mounted onto a conventional curb  2 . It can be seen that the conventional base  14  has a flat, planar upper surface and is strengthened by ribs  16  on its lower surface. The load carrying members  18  of the conventional base  14  are centered atop of curb  2 . Specifically, the curb  2  is mated by design to fit the dimensions of conventional base  14 . 
   Looking at  FIGS. 3 ,  4  and  5  the general arrangement of a floor panel  20  and the manner of joining two or more floor panels can be best seen. Floor panel  20  is a linear member formed from a longitudinally symmetrical “C” channel  22 , and a corrugated top panel  24 , that are adhered together after the injection of an expanding, adhesive foam core  26  between these panels. Top panel  24  has a concave configuration with two flanges extending normally outward from the top linear edge of its parallel sides  38 . Channel  22  has a concave configuration with two substantially similar flanges  34  extending internally and normal from the top linear edge of its parallel sides  36 . The concavity of top panel  24  resides inside the concavity of “C” channel  22 . Insulating adhesive foam  26  holds channel  22  and top panel  24  together. Top panel  24  is not symmetrical about its longitudinal axis. It has a depth of corrugation and a raised profile  28  along its longitudinal axis to impart strength and rigidity. First side  38  of top panel  24  has a flange  32  extending outward and normal. The opposing second side  40  of top panel  24  has a cap flange  30  also extending outward and normal but is formed into an interlocking cap that is dimensioned so as to reside atop of first flange  32  of an adjacently positioned floor panel  20 . Adjacent floor panels  20  are connected by mechanical fasteners  42  that pass through abutting sides  36 . These fasteners  42  are applied before panel  20  is fully assembled and foam  26  installed. Although not illustrated, it is known that the method of mechanical fastening by crimping together the metal of adjacent panels is an acceptable, commonly used alternative to the use of nuts and bolts, screws, rivets, pins etc. 
     FIG. 6  shows a perspective side view of three connected floor panels  20  prior to the injection of insulating foam. It is a notable distinction between the base of the present invention and conventional rooftop A/C unit bases, that base  14  has a smooth, planar bottom surface  44  and a corrugated upper surface which is shaped into folds or parallel and alternating ridges and grooves. This design is an inversion of the conventional bases, which have smooth, planar upper surfaces and ribbed or corrugated bottom surfaces, as can be seen in  FIG. 2 . 
   FIGS.  1  and  7 - 10  taken together, best illustrate the use and advantages of this rooftop A/C base  14 . Curbs, due to the necessary linear alignment of components, are of a rectangular geometry having a width designated as X in  FIG. 1 , and a length designated as Y in  FIG. 1  wherein the length Y is always the longest of these two dimensions. Panel  20  has a width designated as XX in  FIG. 6 , and a length designated as YY in  FIG. 6  wherein the length YY is always the longest of these two dimensions. The panels  20  are always placed relative to the curb  2  such that the panel length YY is perpendicular to the curb length Y. In this manner the structural strength of the panel&#39;s parallel and alternating ridges and grooves (corrugation) can offer the most rigidity to the base  14 . Since the base  14  has a smooth bottom  44 , the base width (which is panel length XX) is not dependent upon the curb width X as can be seen by the placement of base  14  atop the curbs  2  of  FIGS. 7 and 8 . New, retrofit bases can be mounted atop existing curbs without strict dimensional mating, provided that the curb width X does not exceed the panel length YY and first panel clip width combined. (The first panel clip  56  is discussed herein.) Since the dimensional sizes of the bases of the major manufacturers vary only slightly, the panel length YY is selected to exceed most commonly utilized curb widths X. In the case of a curb with a width x that exceeds the panel length YY, a first panel clip  56  may be used to extend the base width/panel length. 
   The panel interconnection system is not designed to be strong enough to allow panels  20  to carry loads if there is not some load bearing member in contact with that panel&#39;s bottom  44 . 
   In contrast, the base length may be considerably shorter than the curb length Y. In that case, cover panels may be installed atop the curb  2  that prevent the ingress of water to the interior bounded area of curb  2 . 
   Stated differently, the base width is equal to or greater than the curb width X, while the base length can be shorter than, equal to, or longer than the curb length Y. 
   Contrasting  FIG. 6  with  FIGS. 9 and 10  it can be seen that in a complete base  52  the end panel  54  has its cap flange  30  trimmed so as to have the flange edge end not extend beyond the side  36  of channel  22 . 
   Looking at  FIGS. 11 and 12  the first embodiment wall panel clip  56  and second embodiment wall panel clip  58  can be seen in their differing applications. These clips differ in their ability to carry a load. First clip  56  is stronger than second clip  58  but because first clip  56  has a strengthening rib  66 , there are physical limitations as to the location of curb  2  underneath. Other than the elimination of rib  66  on second panel clip  58 , the clips are substantially identical. These clips are used to attach the unit walls  60  to the unit base  14 . As discussed above, if the curb width X exceeds the panel length YY, first panel clip  56  may be used to widen the base  14  by the dimension of the clip  56  as well as attach the unit walls  60 . When the panel length YY is longer than the curb width X, second clip  58  may be used to secure the unit walls  60  to the unit base. 
   First panel clip  56  has an upper plate  68  and a lower plate  70  which projects normally from the first side  74  of folded plate  72  so as to be held in a parallel planar configuration. The spacing between upper plate  68  and lower plate  70  is adapted to accommodate the thickness of a panel  20 . Wall support plate  78  extends normally from the second side  76  of folded plate  72  so as to be held in a parallel planar configuration with upper plate  68  but sharing a common plane with lower plate  70 . Unit wall  60  resides on the upper surface of wall support plate  78  while the lower surface of wall support plate  78  resides atop curb  2 . A wall sealing flange  80  extends normally and downward from wall support plate  78  to allow a moisture proof seal with unit wall  60 . Strengthening rib  66  projects normally and downward from lower plate  70 . This rib  66  serves the purpose of adding strength to lower plate  70  thereby preventing deformation of plate  70  by panels  20  that transmit heavy loads onto clip  56 , and maintaining the planar alignment of all panels  20 . 
   In the case of second panel clip  58 , while unit wall  60  resides on the upper surface of wall support plate  78 , the lower surface of wall support plate  78  does not reside atop curb  2 . Since it is used where the bottom surface  44  of panel  20  resides atop curb  2 , there is no need for the strengthening rib  66  as the alignment of panels  20  is not an issue. 
   Both first panel clip  56  and second panel clip  58  are mechanically fastened to panel  20  by a suitable fastener  64 , such as a nut and bolt assembly, that passes through the panel  20  and clip, normal to the longitudinal axis of the panel  20 . This fastening arrangement is identical whether along the panel length YY or panel width XX. These clips may be made as shorter units wherein multiple clips will be needed per side, however, the preferred embodiment clips are sized to be the approximate length of each side of the base  14  such that only four clips are used in a standard, rectangular base  14 .  FIG. 13  illustrates a solid extruded version base and first wall panel clip  90 . 
   The above description will enable any person skilled in the art to make and use this invention. It also sets forth the best modes for carrying out this invention. There are numerous variations and modifications thereof that will also be apparent to others skilled in the art, now that the general principles of this invention have been disclosed.

Summary:
The present invention relates to improved base for a large, commercial rooftop air conditioning (A/C) unit. The base is assembled from a series of interconnectable, corrugated floor panels having smooth bottom planar surfaces that may directly be mounted atop existing rooftop A/C unit curbs. The panels are each constructed from metal or steel, concave formed linear members that reside coplanar and are separated by a foam core. There is a base to wall panel connecting rail that simplifies the attachment of the A/c unit&#39;s side walls.