Abstract:
An evaporative cooling system is disclosed. The system includes a housing including a metal base sheet and a metal side wall and having at least one opening fitted with an evaporative medium pad and an exhaust vent. A pump is configured to disperse water over the evaporative medium pad. A pan is configured to receive the water. The pump is configured to cooperate with the pan to recirculate the water. An exhaust fan is configured to draw air into the housing through the evaporative medium pad and out the exhaust vent. The metal side wall of the housing is at least partially pressed into the metal base sheet of the housing to form a joint having a corrosion resistant coating.

Description:
FIELD 
   The present invention relates generally to the field of heat exchange systems and more particularly to evaporative cooling systems. 
   BACKGROUND OF THE INVENTION 
   It is generally known to provide an evaporative cooler. Such known evaporative coolers are typically adapted for locations where the air is hot and the humidity is low. Such known evaporative coolers operate on the principle of heat absorption by moisture evaporation. Such known evaporative coolers typically draw exterior air into pads soaked with water, where the air is cooled by evaporation and then circulated. The housings of such known evaporative coolers are typically assembled by spot welding galvanized sheets of metal and then powder painting the resulting assembly or by bolting painted sheets of metal together. However, such known evaporative coolers may undergo corrosion from the water over time, especially at the unpainted surfaces of the welded joints of the housing or at the surfaces where the sheets are bolted together. Further, bolting can damage the sheets and provides a non-permanent fastener which may be loosened. 
   It is also generally known to provide the joining of material using “TOX” systems and methods commercially available from TOX PRESSOTECHNIK GmbH &amp; Co. KG of Weingarten, Germany. According to such known TOX systems and methods, a punch presses the materials to be joined into a cavity. As the force continues to increase, the punch side material is forced to spread outward within the die side material resulting in a joint without burrs or sharp edges on which corrosion could form. However, such known TOX systems and methods are typically used in the automotive industry (e.g. sunroofs, engine bonnets, etc.) and are not known to be used with the housing of an evaporative cooler. 
   It is also generally known to provide the joining of material using the “TOG-L-LOC” sheet metal joining system commercially available from BTM Corporation of Marysville, Michigan. According to such known TOG-L-LOC sheet metal joining system, a joint is produced in a single stroke by punch and die tooling fitted to a conventional press. Such known TOG-L-LOC sheet metal joining systems offer numerous advantages: no rivets or fasteners, no secondary operations, reduced and simplified maintenance, no transformers or cooling lines, no heat buildup, joining of dissimilar metals and coated metals, leak proof joints, high repeatability, non-destructive checking, long tool life, etc. However, such known TOG-L-LOC sheet metal joining systems are not known to be used with the housing of an evaporative cooler. 
   It would be desirable to provide a heat exchange system such as an evaporative cooler having a housing that is assembled using a clinching technique. It would further be desirable to provide an evaporative cooler that does not require invasive fasteners or welding equipment to assemble. It would also be desirable to provide an evaporative cooler having pre-painted metal parts. It would further be desirable to provide an evaporative cooler that can be shipped as an unassembled kit of parts. It would still further be desirable to a heat exchange system having one or more of these or other advantageous features. 
   SUMMARY OF THE INVENTION 
   The present invention relates to an evaporative cooling system. The system comprises a housing comprising a metal base sheet and a metal side wall and having at least one opening fitted with an evaporative medium pad and an exhaust vent. The system also comprises a pump configured to disperse water over the evaporative medium pad. The system also comprises a pan configured to receive the water. The pump is configured to cooperate with the pan to recirculate the water. The system also comprises an exhaust fan configured to draw air into the housing through the evaporative medium pad and out the exhaust vent. The metal side wall of the housing is at least partially clinched, without fasteners to the metal base sheet of the housing to form a joint having a corrosion resistant coating. 
   The present invention also relates to a kit for assembling an evaporative cooling system. The kit comprises a housing comprising a base sheet and a side wall. The kit also comprises an evaporative medium pad configured to couple to the housing. The kit also comprises an exhaust vent configured to couple to the housing. The kit also comprises a pump configured to disperse water over the evaporative medium pad. The kit also comprises a pan configured to receive the water. The kit also comprises an exhaust fan configured to draw air into the housing through the evaporative medium pad and out the exhaust vent. Substantially all surfaces of the side wall and the base sheet of the housing have a corrosion resistant coating. 
   The present invention also relates to a method of making an evaporative cooler having a housing comprising a base sheet and a side sheet. The method comprises bending an edge of the base sheet to form a base flange. The method also comprises applying a corrosion resistant coating to the base sheet and the side sheet. The method also comprises clinching a portion of the side sheet and a portion of the base flange thereby forming a joint comprising the side sheet at least partially pressed into the base flange. 
   The term “crimp” as used in this disclosure is intended to have its commonly understood or general meaning (e.g. press or pinch into small regular folds or ridges). 
   The term “clinch” as used in this disclosure is intended to have its commonly understood or general meaning (e.g. to hold firmly, to hold fast by grasping or embracing tightly, to bend or turn over the point of so that it will hold fast). 
   The term “coating” as used in this disclosure is intended to be a broad term and not a term of limitation. The term “coating” as used in this disclosure may include, without limitation any decorative or functional surface treatment, paint, liquid dispersion, finish, surface finish, varnish, pigment, colorant, powder coating, other coating, etc. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front perspective view of a heat exchange system according to a preferred embodiment. 
       FIG. 2  is a rear perspective view of the heat exchange system of  FIG. 1 . 
       FIG. 3  is a sectional view of the heat exchange system of  FIG. 1  according to an alternative embodiment. 
       FIG. 4  is an exploded perspective view of the heat exchange system of  FIG. 1  according to an exemplary embodiment. 
       FIG. 5  is a fragmentary sectional view of the heat exchange system of  FIG. 1  according to a preferred embodiment. 
       FIG. 6A  is an exploded fragmentary sectional view of a case for the heat exchange system of  FIG. 1  in a pre-assembled condition according to an exemplary embodiment. 
       FIG. 6B  is a fragmentary sectional view of the case of  FIG. 6A  in an assembled condition according to an exemplary embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A heat exchange system or heat exchanger is shown as an evaporative cooler  10  in  FIGS. 1 and 2  according to a preferred embodiment. Evaporative cooler  10  includes a casing or housing  20  encapsulating a cooling system  70  (see  FIG. 3 ). The walls of housing  20  are connected by a crimped or clinched joint  50 . The uniformity of the surface of a corrosion resistant coating  60  provided over the walls of housing  20  is not broken or damaged by the clinching of joint  50  according to a preferred embodiment as shown in  FIG. 5 . 
   According to a preferred embodiment, the housing may be shipped as an unassembled or partially assembled, relatively compact kit of parts or pieces, including the relatively flat cover, base and side walls of the housing. Substantially all surfaces of the housing are coated with the corrosion resistant coating prior to assembly of the housing according to a preferred embodiment. The joints may be formed on-site (e.g. by clinching) upon receipt of the kit without screwing or riveting the parts together with an invasive fastener or weld (which can lead to corrosion). Thus, the assembly of the kit can be done in any location with simple equipment. 
   Referring to  FIG. 3 , evaporative cooler  10  is shown according to an alternative embodiment. A water distribution network  82  in housing  20  disperses water over two evaporative media pads  80  supported by a tray  94  in housing  20  (see  FIG. 4 ). An air intake or louver vent  38  draws exterior air through and/or across pad  80  (soaked with water) (see  FIG. 3 ). The temperature of the exterior air is reduced or cooled due to evaporation of the water. 
   Referring further to  FIG. 3 , the cooled air is drawn out of housing  20  by an exhaust system  90 . Exhaust system  90  includes a motor  92  connected to a pulley  88  of a blower  96  for venting the cooled air to a desired location such as a work or residential space. Housing  20  includes a dry chamber  22  and a wet chamber  24  (see  FIG. 1 ). Dry chamber  22  is intended to be substantially free of water. Dry chamber  22  provides an area intended for blowing the cooled air to the desired location with exhaust system  90 . Wet chamber  24  is intended as an area for supporting evaporative media pad  80  and an area for the evaporation of water from pad  80 . 
   Wet chamber  24  may include a water recirculation system  72  for recycling non-evaporated water from a pan  98  back to evaporative media pad  80  as shown in  FIG. 3  according to an alternative embodiment. Recirculation system  72  includes a sensor (shown as a float  74 ) for providing a signal representative of the volume of water in a pan  98 . Recirculation system  72  also includes a pump assembly  76  having a water pump  78  connected to water distribution network  82  by a hose  84 . Water distribution network  82  provides for the dispersion of the recycled (as well as “original” or source water) over evaporative media pad  80 . 
   Referring to  FIGS. 1 ,  2  and  4 , housing  20  of evaporative cooler  10  comprises four side walls  36   a ,  36   b ,  36   c  and  36   d  each connected to a base  32  and a cover  34 . Cover  34  includes a removable panel  28  connected by a removable invasive fastener (shown as a bolt  102 ) to a panel  40   a  of side wall  36   a  and a panel  40   c  of side wall  36   c  for providing access to wet chamber  24 . Side wall  36   a  includes a removable panel  26   a  and panel  26   c  attached (e.g. by friction fit along an edge or vertically upright base flange  42 ) to base  32  and cover  34  for providing access to dry chamber  22 . Vent  38  of side wall  36   b  provides for the intake of outside or exterior air into housing  20 . The side walls, base and cover are each a sheet of metal material such as galvanized steel according to a preferred embodiment. 
   Referring to  FIGS. 2 and 4 , joint  50  is shown connecting an exterior surface  44  of flange  42  and an interior surface  46  of a vertical post or frame  48  of side wall  36   a . Joint  50  is formed by “punch” pressing (e.g. with a punch and die) flange frame  48 , thereby forming a ridge or fold  52  (see  FIG. 5 ). Fold  52  includes a recess  54  outlined by a protrusion  56 . Referring to  FIG. 5 , a portion  106  of frame  48  overlies a portion  108  of flange  42  on both sides of joint  50  and forms the mechanical interlock. In one embodiment, the joint is circular. 
   Referring to  FIG. 6A , base  32  and frame  48  are shown prior to assembly of housing  20  according to an exemplary embodiment. Base  32  includes flange  42  as shown in  FIG. 6A  formed by bending a flat piece of sheet metal. To fasten flange  42  to frame  48  during assembly of housing  20 , flange  42  is positioned to engage frame  48 . Joint  50  is then formed by clinching (e.g. pressing or folding and mechanically interlocking) flange  42  and frame  48  as shown in  FIG. 6B . 
   According to a particularly preferred embodiment, joint  50  comprises areas of clinching (shown as clinch  58   a , clinch  58   b , clinch  58   c  and clinch  58   d  in  FIG. 2 ) to securely fasten the side walls to the cover and the base of housing  20 . The areas of clinching are arranged diagonally according to a particularly preferred embodiment as shown in  FIG. 2 . The center of each of the clinched areas is separated by a horizontal distance  62  and a vertical distance  64  as shown in  FIG. 2 . 
   As illustrated in  FIG. 2 , clinch  58   a  is closest to an upper edge  110  and a side edge  112  of flange  42 . Clinches  58   b ,  58   c  and  58   d  are progressively further from upper edge  110  and side edge  112 , respectively. The locations of the areas of clinching aids to secure the free corner of flange  42 . According to a particularly preferred embodiment as shown in  FIG. 2 , the first area of clinching (e.g. clinch  58   d ) is closer to the peripheral edge of housing  20  (e.g. the fold line of flange  42  opposite upper edge  110 ) than the second, diagonally offset area of clinching (e.g. clinch  58   a ) closest to side edge  112  of housing  20 . 
   According to a particularly preferred embodiment as shown in  FIG. 2 , clinch  58   a  of side wall  36   c  and clinch  58   a  of side wall  36   d  (opposite each other at a corner  114 ) are closer together than clinch  58   b  of side wall  36   c  and clinch  58   b  of side wall  36   d  (opposite each other at corner  114 ). According to a particularly preferred embodiment as shown in  FIG. 2 , clinch  58   a  of side wall  36   c  and clinch  58   a  of side wall  36   d  (opposite each other at corner  114 ) are closer to upper edge  110  and side edge  112  than are clinch  58   b  of side wall  36   c  and clinch  58   b  of side wall  36   d  (opposite each other at corner  114 ). According to an alternative embodiment, the base flanges of the corner may be welded to the side walls. According to another alternative embodiment, the base flanges of the corner may be welded to each other. According to another alternative embodiment, the areas of clinching may be arranged in any pattern (e.g. increasing diagonal, decreasing diagonal, vertical, horizontal, staggered, etc.). 
   According to a particularly preferred embodiment, the horizontal distance between the areas of clinching is about 0.75 inches to about 1.4 inches, and the vertical distance between the areas of clinching is about 0.13 inches to about 0.4 inches. According to a particularly preferred embodiment, at least one of the areas of clinching is offset from the peripheral edge of the housing by about 0.4 inches, and the areas of clinching are each offset from the peripheral edge of the housing by at least about 0.4 inches. 
   According to one embodiment, the joint is formed by the TOX method, which is described in European Patent No. 0 215 449 entitled “Method And Device For Joining Thin Plates” issued to Eugen Rapp on May 22, 1991, which is hereby incorporated by reference. According to another embodiment, the joint is formed by the TOG-L-LOC sheet metal joining system which is described in the following U.S. Patents: U.S. Pat. No. 5,267,383 titled “Apparatus for Joining Sheet Material” issued to Edwin G. Sawdon on Dec. 7, 1993; U.S. Pat. No. 5,031,442 titled “Punch Anvils for Sheet Fastening Systems” issued to Miroslav Kynl on Jul. 16, 1991; U.S. Pat. No. 4,757,609 titled “Apparatus for Joining Sheet Material” issued to Edwin G. Sawdon on Jul. 19, 1988; and U.S. Pat. No. 4,459,735 titled “Joining Sheet Metal” issued to Edwin G. Sawdon on Jul. 17, 1984, each of which are hereby incorporated by reference. 
   Referring to  FIG. 5 , coating  60  is shown covering exterior surface  44  of flange  42  and interior surface  46  of frame  48 . Coating  60  is also shown in  FIG. 5  covering the entire interface  104  between exterior surface  44  and interior surface  46 . According to a preferred embodiment, the base, cover and side wall are covered with a corrosion resistant coating before they are connected to form the joint. 
   According to a preferred embodiment, the coating is a polyester-epoxy, powder coated, multi-layer, bonded treatment. The coating is first applied to heavy gauge, cold-rolled steel and the coating is then built layer by layer according to a preferred embodiment. The coating is intended to provide protection from weathering and corrosion according to any preferred or alternative embodiment. The coating may be a decorative appliance-type surface finish according to an alternative embodiment. 
   Conventional welding of multi-layer coated steel removes all of the protective layers except for the steel. Even if the multi-layer coated steel is painted after welding, the only protective layer in the region of the weld is the paint. The clinch system described herein allows for all of the protective layers to remain intact. As a result, the joined pieces of steel are less likely to rust or be corroded by the chemicals and minerals in the water circulated within the evaporative cooler. 
   The heat exchange system may be placed outdoors as well as indoors according to any preferred or alternative embodiment. The heat exchange system is intended to be placed where there is an abundance of fresh air, and may be positioned adjacent to an open window or external door with additional openings on the opposite side of the room for relief air according to alternative embodiments. In this way, the heat exchange system may draw fresh air from the outside and be drawn through the pad, cooled, filtered and circulated through the room while the hot, stale air is forced out through the openings on the other side of the room. 
   The heat exchange system may be used in a variety of environments, including at least: industrial and commercial settings (e.g. industrial plants, factories, assembly lines, warehouses, commercial kitchens, laundries, dry cleaners, greenhouses, confinement farming (such as poultry ranches, hog, dairy, etc.), retail outlets, garden centers, auto shops, hotels/resorts, etc.); residential settings (e.g. workshops, garages, kennels, horse stables, patios, barns, exercise areas, etc.), outdoor settings (e.g. loading docks, construction sites, athletic events, tented parties, sporting events, pools and patios, outdoor retail etc.), etc. 
   It is important to note that the construction and arrangement of the elements of the heat exchange system as shown in the preferred and other exemplary embodiments is illustrative only. Although only a few embodiments of the present invention have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g. variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, the elements of the housing may be painted before bending according to an alternative embodiment. Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the appended claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present invention as expressed in the appended claims.