Abstract:
The present invention relates to drain pans and the process of making the same, and more particularly to a leak proof drain pan that is semi-stackable during storage and can be manufactured from a single piece of steel without the use of a press, die or tooling. The drain pan includes corner sections created from a unique folding system which eliminates seams and thus the need for any sealing of the seams.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to drain pans, and more particularly to a leak proof drain pan that is semi-stackable during storage and can be manufactured from a single piece of steel without the use of a press, die, welding or tooling. 
         [0003]    2. Description of the Prior Art 
         [0004]    Various types of drain pans are known in the art and can be used in any number of situations for collecting various types of fluids such as oil or water. Such drain pans should be leak free, but require sealants to effectively seal the seams of the drain pan. Drain pans exist in the automotive and trucking industries, and can be used for heavy duty truck and trailer tubeless dual wheels, allowing the user to cleanly and safely drain oil or grease from the axles. Drain pans can also be used in the food industry, where drain pans are placed underneath frying machines to catch cooking oil and grease dripping or to completely drain the cooking oil. Drain pans can be used for water heaters to catch excess water. A household dishwasher can include a drain pan designed to relocate leaking fluids to an observable location. Other types of appliances that can use drain pans include refrigerators and washing machines for catching excess water leaking from the appliance. Drain pans can be used to catch excess grease from underneath barbecue grills and inside home grills. 
         [0005]    A cooling coil used in air conditioning apparatus such as furnaces, air handling units, and heat pumps extracts moisture from the air which is being flowed externally across the coil (by a blower portion of the apparatus) and cooled by the coil for delivery to a conditioned space served by the apparatus. Air flowing across the coil is dehumidified as it is cooled, causing condensation to form on the coil. This condensation must be disposed of to prevent freezing of the coil and damage to the surrounding building structure. Typically, a drain pan is located beneath the coil to receive condensate runoff. The pan includes an opening in a bottom part of the pan to conduct the condensate accumulated in the pan to an external drainage conduit. 
         [0006]    It is advantageous to reduce water retention in the pan to the extent feasible, not only to reduce the likelihood of condensate spillage from the pan onto the adjacent building structure, but also to inhibit the formation of mold, rust and other undesirable byproducts of stagnant water in the pan which may lead to reduction in the quality of air delivered to the conditioned space. Further, air flowing across the heat exchanger cooling coil may pick up moisture from excessive water accumulation in the pan, which may result in unwanted humidity in the air supplied to an indoor space. 
         [0007]    Drain pans of various types are known in the art. These prior art drain pans are typically rectangular in shape and cannot fit inside one another when stacked for storage. Because of limited availability of shelf space in retail establishments, it is desired to stack the drain pans as closely together as possible.  FIG. 10  of the present application shows a typical set of stacked drain pans according to the prior art. As can be seen, the drain pans of the prior art are stacked one on top of another and are not nested together. Thus, stacking multiple drain pans for storage, shipping, etc. will take up more space. 
         [0008]    U.S. Pat. Nos. 4,632,268 and 4,513,865 disclose stackable oil drain pans. As can be seen from  FIGS. 4 and 5  of both references, the drain pan has a male protrusion on top of the pan and a corresponding female indentation on the bottom. When stacked on top of each other, the drain pans do stack more easily. However, the amount of excess space saved from stacking is relatively small. As can be seen from the  FIGS. 4 and 5 , the main body of the drain pans do not fit inside one another. 
         [0009]    Some of the prior art drain pans are nestable when stacked. A typical drain pan of this nature is shown in U.S. Pat. No. 6,718,788. However, this drain pan has a big disadvantage based on the manufacture of the drain pan itself. The drain pan is fabricated by use of a press, die and tooling. The drain pan is pressed into a die and the corners are crimped to form the usual rectangular shape with crimped corners. The type of press used is a large hydro-formed press which includes tooling to manufacture only one size at a time. Each different size drain pan requires a different die with separate tooling. Since the die and tooling must be custom made to accommodate each drain pan size, the manufacturing costs are high. Thus, manufacture of this type of drain pan is very expensive and is not easily adaptable for fabricating different size drain pans unless large numbers of each size of pan are made. 
         [0010]    Furthermore, during the foregoing manufacturing process using the press, the large force exerted by the press to form the drain pan can cause the steel to crack at the corners. If these cracks are not found at the time of manufacture, this can create possible leakage of the condensate when the drain pan is in use. Hair-line cracks in steel are often not visible to the naked eye. Therefore, the prior art drain pans have some major disadvantages. 
         [0011]    Some of the prior art nestable pans, such as the drain pan disclosed in U.S. Pat. No. 6,718,788, can become jammed when stacked, making removal of the pans tedious and slow. If there is tight stacking, it might not be possible to separate the drain pans. 
         [0012]    It would be advantageous to reduce the amount of space the drain pans occupy when stacked upon one another for storage or shipping purposes. In this regard, it would be useful for a drain pan to fit inside another drain pan. 
         [0013]    Furthermore, it would be an advantage to significantly reduce the costs and time associated with the manufacture of drain pans by eliminating the need for a die and tooling to be used with a press. The elimination of the press during the manufacturing process would also reduce the likelihood of cracks or flaws in the drain pan. 
         [0014]    As can readily be seen from the foregoing, a need exists for a drain pan structure which eliminates or at least substantially reduces the above-mentioned problems, limitations and disadvantages of conventionally constructed drain pans. It is to this need that the present invention is directed. 
       SUMMARY OF THE INVENTION 
       [0015]    As described in the Description of the Prior Art, drain pans are known in the art and can be used in any number of situations for collecting various types of fluids such as oil or water in the form of condensation. Such drain pans should be leak free, but require sealants to effectively seal the seams of the drain pan. 
         [0016]    An object of the present invention is to provide a drain pan which is leak proof and can be manufactured without the need of a press, die and tooling. 
         [0017]    Another object of the present invention is to provide a drain pan which can be manufactured easily at relatively low cost and is easily adaptable for being manufactured in various sizes. 
         [0018]    Yet another object of the present invention is to provide a drain pan that can be manufactured from one piece of steel or other appropriate metal, wherein the single piece of steel or other metal is folded upon itself to form the drain pan, without the formation of hairline or other types of cracks. 
         [0019]    A further object of the present invention is to provide a drain pan which is semi-stackable for reducing the space on the shelves of wholesalers and other storers of such pans. 
         [0020]    Another object of the present invention is to provide a drain pan which does not require the use of sealants to prevent leaks. 
         [0021]    Still yet another object of the present invention is to provide a drain pan with a drain plug that can be located on any side of the drain pan for preventing overflow of the pan. 
         [0022]    The foregoing objects are achieved according to the preferred embodiment of the invention by the provision of a drain pan from a single piece of sheet metal which is uniquely folded to create a seamless drain pan. The drain pan includes folded corner sections which are folded toward the inner portion of the drain pan as described below, which enables the stacking of the drain pans in a stable manner, with easy placement of drain pans in the stack and fast removal therefrom, without any possibility of jamming. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Other characteristics and advantages of the present invention will emerge from reading the detailed description hereinbelow of nonlimiting embodiments of the invention, and examining the attached drawings wherein: 
           [0024]      FIG. 1  is a perspective view of the leak free semi-stackable drain pan. 
           [0025]      FIG. 2  is a section view of the drain pan of  FIG. 1  taken along the line  2 - 2 . 
           [0026]      FIG. 3  is a section view of the drain pan of  FIG. 1  taken along the line  3 - 3 . 
           [0027]      FIG. 4  is an enlarged perspective view of an unfolded corner of the drain pan of  FIG. 1  showing dotted lines where the drain pan will be folded. 
           [0028]      FIG. 5  is an enlarged perspective view of a partially folded corner of the drain pan of  FIG. 1  showing the direction of the folds indicated by arrows. 
           [0029]      FIG. 6  is an enlarged perspective view of a corner of the drain pan of  FIG. 1  showing the direction of the final fold of indicated by arrows. 
           [0030]      FIG. 7  is an enlarged perspective view of a corner of the drain pan of  FIG. 1  showing a completely folded corner with completely folded top edges. 
           [0031]      FIG. 8  is a top view of the drain pan of  FIG. 1  as a single sheet of metal completely unfolded, prior to its fabrication into a drain pan. 
           [0032]      FIG. 9  is a front view of multiple drain pans of  FIG. 1  placed upon one another in a semi-stackable fashion. 
           [0033]      FIG. 10  is a front view of multiple drain pans according to the prior art in a stacked configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0034]    As discussed throughout the specification, the term “crimp” or “crimped” means corrugated or to produce a corrugated surface. The term “semi-stackable” means that one drain pan is inserted with its open top facing upwards, into a lower drain pan with its open top facing upwards, with the upper edge of the inserted end wall contacting the inside of the corresponding end wall of the drain pan into which the inserted drain pan is being placed, and the lower edge portion of the opposite end wall of the inserted drain pan resting on the upper edge of the end wall of the lower drain pan so that the drain pan at the top of the stack can be easily grasped to enable lifting of the pan from the stack. The inclination of the next drain pan in the stack is reversed to limit the tilting of the stack. An example of stacking of the semi-stackable drain pan is shown in  FIG. 9 . 
         [0035]    Disclosed according to the present invention is a drain pan and a method of producing the drain pan. As will be more fully explained hereinafter, the drain pan of the present invention is preferably folded from a single sheet of steel or similar material without the use of a press and the necessary die and tooling associated with the press. The drain pan is semi-stackable for reducing the space on the shelves of wholesalers, and making removal of one or more drain pans easy whether done manually or with an appropriate tool or appropriate equipment. 
         [0036]      FIG. 1  shows a perspective view of the leak free semi-stackable drain pan generally designated at  10 . Drain pan  10  is seamless and does not leak. As shown, drain pan  10  is substantially square shaped and includes a bottom wall  12  which can have a width of about 24 inches width and a length of 24 inches. However, drain pan  10  is not limited by these dimensions or being substantially square shaped and could retain other shapes such as a rectangle, for example, depending upon the application of the drain pan and the different sizes of the air conditioner. Drain pan  10  could also be curved or have irregular shapes as well. Drain pan  10  also includes a front wall  14 , a rear wall  16  and two side walls  18 . Front wall  14  and rear wall  16  are substantially parallel to each other and substantially perpendicular to bottom wall  12 . Side walls  18  are also substantially parallel to each other and substantially perpendicular to bottom wall  12 . Front wall  14  and rear wall  16  are substantially perpendicular to sidewalls  18 . As seen in  FIG. 1 , side walls  18  also include corner sections  20  on the inside of drain pan  10  resulting from the folding of the corners of drain pan  10  as discussed later. Top edge portions  22 A,  22 B and  22 C are located on the inside of front wall  14 , rear wall  16  and side walls  18  respectively, and are modified as described below, to serve to protect a user handling drain pan  10  from any sharp edges of the sheet metal. Top edge portion  22 C overlaps corner sections  20  of each sidewall  18  as shown in  FIG. 1 . A drain fitting  24  is located on the outside of front wall  14  to drain the water or condensation retained by drain pan  10 . In use, drain fitting  24  is hermetically sealed in drain pan  10  and thus does not have any leaks. When installed in an air conditioner, freezer or refrigeration unit, for example, a hose is attached to drain fitting  24  in the manner shown in U.S. Pat. No. 6,718,788 for draining condensates from drain pan  10 . Drain fitting  24  can advantageously include as an integral unit, a cylindrical tube or male adaptor  25 A extending from a nut portion  25 B from which extends an externally threaded tubular portion extending through wall  14  (or some other wall). Male adaptor  25 A is held in place by internal nut or fastener  26  screwed to abut the inside surface of wall  14 , and a gasket  27  is located between nut portion  25 B and the external surface of wall  14 . 
         [0037]    Drain pan  10  is formed by folding of a blank  40  as shown by the fictitious fold lines shown in  FIG. 8 . Drain pan  10  is not crimped, meaning it does not have corrugated surfaces. Preferably the blank is made from steel and usually is made of sheet metal. An appropriate thickness is 0.0193 inches. However, other materials that create a rigid, leak proof drain pan when folded can also be used. The sheet metal is cut to the desired blank size. The dotted lines shown in  FIG. 8  display where blank  40  is folded to create drain pan  10  in  FIG. 1 . Each section separated by the dotted lines substantially corresponds to the parts of drain pan  10  as described above. Bottom wall  12  is substantially square-shaped although it is not limited to this embodiment as mentioned above. Blank  40  also includes front wall  14 , rear wall  16  and side walls  18 . A drain plug hole  30  is punched out of front wall  14  to accommodate drain plug  24 . Drain plug hole  30  can be also located in rear wall  16  or side walls  18 . Of course, more than one drain plug hole  30  can be punched to accommodate multiple drain plugs  24 . Top edges  22  are also part of blank  40  and are located on each front wall  14 , rear wall  16  and side walls  18  respectively. Top edge portions  22 A,  22 B and  22 C are slightly chamfered at each end to allow for clearance when folded over at each corner section  20 . Of course it is possible that top edge portions  22 A,  22 B and  22 C are not chamfered at all or may be rounded. Top edge portions  22 A,  22 B and  22 C do not have to be included in drain pan  10 , but they are rendered smooth as discussed below to prevent them from cutting a person or items during handling and use, and to prevent them from scratching other drain pans during stacking. 
         [0038]    Corner sections  20  are further defined as seen in  FIGS. 4 and 5 . Corner section  20  includes an outside corner  28  and an inside corner  29 .  FIG. 4  shows a magnified corner section  20  in more detail. Corner section  20  has four sides as defined by lines A and B, and phantom lines C and D. As seen in  FIG. 4 , a phantom line H diagonally bisects corner section  20  from outside corner  28  to inside corner  29  creating a top corner section  28 A and bottom internal corner section  29 A which are substantially the same size. An angle a is the angle between line B and phantom line D. α is also the angle between line A and phantom line C. As shown in  FIG. 4 , a is about 95 degrees. However, α is not limited to being 95 degrees and can either be an acute, obtuse or a right angle. As shown in  FIG. 8 , the edges between front wall  14  and rear wall  16 , and bottom wall  12  are shown by phantom lines E and F, respectively. The edges between side walls  18  and bottom wall  12  are shown by phantom lines G. 
         [0039]      FIGS. 5 ,  6  and  7  show the folding of corner section  20  as well as front wall  14 , side wall  18  and top edge portions  22 A,  22 B and  22 C. First, considering drain pan  10  in an unfolded condition and initially in a ground engaging position as shown in  FIG. 8 , the portion of sheet metal including phantom line H is forced upward from bottom wall  12  by hand or suitable machine, rotating top corner section  28 A about bottom internal corner section  29 A. Outside corner  28  is thus moved upwardly and inward as shown by arrow X towards bottom wall  12 . At the same time, side wall  18  and front wall  14  are forced to fold inwardly as shown by arrows Y and Z respectively, about edges. Since top edges  22 C and  22 A are attached to side walls  18  and front wall  14 , respectively, they too are pulled inward. However, top edges  22  are not yet folded over. When side walls  18  and front wall  14  become substantially perpendicular to bottom wall  12 , top corner section  28 A and bottom internal corner section  29 A should be substantially coplanar. That is, lines A and B should be collinear and lines C and D should be collinear. Next, corner section  20  is folded either towards side wall  18  or front wall  14 . In  FIG. 6 , corner section  20  is folded towards side wall  18  until it is substantially coplanar with side wall  18 . 
         [0040]    Next, top edge  22 A of front wall  14  is folded inward at 180 degrees along phantom line I as seen in  FIG. 6 .  FIGS. 4 and 5  show phantom line I before folding. The folding over of top edge  22 A is for safety and prevents any sharp surfaces of blank  40  from cutting or injuring a user when handling drain pan  10 . This same folding procedure is repeated for the other three corner sections  20 . Finally, each top edge  22 C of each side wall  18 , as shown in  FIG. 6 , is folded inward at 180 degrees along dotted line L. Arrow J shows part of top edge  22  folding over part of corner section  20  to the position shown in  FIG. 7 . Arrow K shows the remaining part of top edge  22 C folding over part of side wall  18 . It is important that these top edges  20 C are folded last, since they help secure corner sections  20  and prevent them from unfolding at each corner of drain pan  10 . After the folding is complete, drain fitting  24  is inserted into drain hole  30  and is hermetically sealed by means of nut  25 B and gasket  27  as explained earlier. Drain pan  10 , which was created from blank  40 , is now seamless and leak proof. No sealing around the corners or any part of drain pan  10  is necessary. Furthermore, no press, die or tooling was needed to create drain pan  10 . Thus, drain pan  10  is relatively inexpensive to manufacture and creates significant cost savings compared to the previous drain pans created from a press. 
         [0041]    After multiple drain pans  10  of the same size have been manufactured, they can be stacked as seen in  FIG. 9  for storage purposes in the semi-stackable arrangement to reduce the space on the shelves of wholesalers or for shipment. The stacking configuration shown in  FIG. 9  allow for twice the number of drain pans  10  to be stacked compared to the prior art drain pans as seen stacked in  FIG. 10 . 
         [0042]    Having described the invention, it will be apparent to those skilled in the art that alterations and modifications may be made without departing from the spirit and scope of the invention limited only by the appended claims.