Abstract:
An apparatus and method for a panel construction for an air-handling unit includes at least one base member having a top surface and a bottom surface opposite the top surface and a skin having opposed surfaces. An insulator having opposed surfaces is disposed between the top surface of the at least one base member and the skin, one surface of the insulator being securely connected to the top surface of the at least one base member and the other surface of the insulator being securely connected to one surface of the skin. The secure connections between the opposed surfaces of the insulator and the top surface of the at least one base member and one surface of the skin substantially preventing a continuous path of substantially reduced thermal insulative properties between the at least one base member and the skin.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention is directed to a base construction for an air handling unit, and more particularly, to a base construction for an air handling unit having improved thermal properties.  
       BACKGROUND OF THE INVENTION  
       [0002]     Air Handling Units (AHUs) are one of several components in cooling and heating systems. They are an important component because the AHU houses a number of components used in the system to provide forced air for climate control in a particular structure. AHU components typically include motors, heating/cooling coils, and blowers as well as the required interface connections to effect such climate control.  
         [0003]     The AHU is an enclosed interconnected framed panel structure. The framed panel structures include substantially thermally insulated panels that are supported between framing members, to define interconnected rectangular compartments. Although the panels are substantially thermally insulated, structural members are typically disposed between opposed skins to enhance the structural strength properties of the panel. Typically, the structural members and opposed skins, which are of metal construction, are secured together by metal screws. Therefore, despite the addition of insulating material between the skins, there is an amount of metal-to-metal contact between the opposed skins, which provides a continuous path of substantially reduced thermal insulative properties between the opposed skins. This reduction of thermal insulative properties adversely affects the efficiency of the cooling and heating system.  
         [0004]     Similarly, the AHU is typically supported by robust base members, such as I-beams or C-channels. A layer of metal sheet often overlays the base members and serves as a floor for the AHU, with the floor being secured to the base members by metal fasteners. Despite the addition of insulating material layers and/or “air space” disposed beneath the floor and between the floor and the insulating material layers, there remains an amount of metal-to-metal contact between the base members and the floor which reduces the system efficiency of the cooling and heating system.  
         [0005]     In addition, the atmospheric pressure inside the AHU can be significantly less than the atmospheric pressure outside of the AHU. Such difference in pressure subjects the floor to significant forces acting to draw the floor upwardly from the base members. Current measures to address this problem include using multiple mechanical fasteners to secure the floor to the base members and additionally significantly increasing the thickness of the floor. Not only do these measures increase the cost and weight of the AHU, but these measures fail to eliminate metal-to-metal contact between the base members.  
         [0006]     Finally, the addition of through mechanical fasteners to secure the floor to the base members necessarily requires that apertures be formed in the floor to receive the fasteners. The floor is then susceptible to leakage of condensation that collects during operation of the AHU, despite attempts to seal the floor.  
         [0007]     What is needed is an improved base construction that does not include a continuous path of substantially reduced thermal insulative properties between the floor and base members that is not susceptible to condensation leakage through the floor while permitting a decreased floor thickness.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention relates to a base construction for an air handling unit including at least one base member having a top surface and a bottom surface opposite the top surface and a skin having opposed surfaces. An insulator having opposed surfaces is disposed between the top surface of the at least one base member and the skin, one surface of the insulator being securely connected to the top surface of the at least one base member and the other surface of the insulator being securely connected to one surface of the skin. The secure connections between the opposed surfaces of the insulator and the top surface of the at least one base member and one surface of the skin substantially preventing a continuous path of substantially reduced thermal insulative properties between the at least one base member and the skin.  
         [0009]     The present invention further relates to a base construction for an air handling unit including at least one base member having a top surface and a bottom surface opposite the top surface and a skin having opposed surfaces. An insulator having opposed surfaces is disposed between the top surface of the at least one base member and the skin. One surface of the insulator is securely connected to the top surface of the at least one base member and the other surface of the insulator is securely connected to one surface of the skin. The secure connections between the opposed surfaces of the insulator and the top surface of the at least one base member and one surface of the skin substantially preventing a continuous path of substantially reduced thermal insulative properties between the at least one base member and the skin. At least one bracket is connected to the skin, the at least one bracket being disposed adjacent to the at least one base member. The at least one bracket has a leg disposed substantially parallel to the skin and at least partially overlapping the top surface of the at least one base member. A layer of an insulating material is applied over the skin, wherein the layer substantially fills a space between the leg and the top surface of the at least one base member with insulating material.  
         [0010]     The present invention still further relates to a method of constructing a base for an air handling unit. The method includes providing at least one base member to support an air handling unit, the at least one base member having a top surface and a bottom surface opposite the top surface and securely connecting one surface of an insulator having opposed surfaces to the top surface of the at least one base member. The method further includes securely connecting one surface of a skin having opposed surfaces to the surface of the insulator opposite the at least one base member and securely connecting one or more bracket to the skin. The one or more bracket is disposed adjacent to the at least one base member, the at least one bracket having a leg disposed substantially parallel to the skin and at least partially overlapping the top surface of the at least one base member. The method further includes applying a layer of an insulating material over the skin, wherein the layer substantially fills a space between the leg and the top surface of the at least one base member with insulating material.  
         [0011]     An advantage of the present invention is that it provides improved thermal insulative properties for air handling unit floors.  
         [0012]     A further advantage of the present invention is that the number of parts is reduced.  
         [0013]     A yet further advantage of the present invention is that the air handling unit floor is not susceptible to condensation leakage through the floor.  
         [0014]     A still further advantage of the present invention is that the air handling unit floor is strengthened without increasing the floor thickness.  
         [0015]     Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a perspective cutaway view of a base of an AHU of the present invention.  
         [0017]      FIG. 2  is a cross section of a base of an AHU taken along line  1 - 1  of the present invention.  
         [0018]      FIG. 3  is an enlarged, partial cross section of a base of an AHU taken along line  1 - 1  of the present invention.  
         [0019]      FIG. 4  is an enlarged, partial cross section of a base of an AHU taken along line  1 - 1  of the present invention.  
         [0020]      FIG. 5  is an enlarged partial cross section of an alternate bracket construction of an AHU of the present invention.  
         [0021]      FIG. 6  is an enlarged partial cross section of an alternate base construction of an AHU of the present invention.  
         [0022]      FIG. 7  is an enlarged partial end view of a connection between a pair of base construction segments of an AHU of the present invention.  
         [0023]      FIG. 8  is an enlarged partial exploded view of an alternate wall panel construction of an AHU of the present invention.  
         [0024]      FIG. 9  is an enlarged partial end view of an alternate base construction shown supporting a wall panel of an AHU of the present invention. 
     
    
       [0025]     Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     One embodiment of a base  20  for an AHU  10  of the present invention is depicted in  FIG. 1 . Preferably, referring to  FIGS. 2-4 , the base  20  includes a plurality of base members, such as I-beams  22  and C-channels  24 , to support the AHU  10 . The I-beams  22  and C-channels  24  are spaced apart, preferably parallel to each other, to provide structural stiffness and strength. In one embodiment, the I-beams  22  are arranged along the periphery of the base  20 , with the C-channels  24  arranged at equal spacing between opposed I-beams  22 . Once the I-beams  22  and C-channels  24  are arranged, a bracket  28  having substantially perpendicular legs  30 ,  32  is secured atop the peripherally arranged I-beams  22 , followed by securing a layer of insulating material  26  atop each of the base members  22 ,  24 . After securing the insulating material  26 , a floor skin or skin  38 , including a plurality of brackets  36  corresponding to the base members  22 ,  24 , is secured atop the insulating material  26 , followed by an application of a layer of insulating material  52  ( FIG. 4 ) over the bracket  36 . As will be discussed in further detail below, the AHU  10  lacks a continuous path of substantially reduced thermal insulative properties between the base members  22 ,  24  and skin  38 .  
         [0027]     After arranging the I-beam  22  and C-channel  24  base members, leg  30  of bracket  28  is secured to the upper surface of the I-beams  22 , such as by a mechanical fastener  48 , although adhesives, welding and other known methods may also be used. Preferably, leg  32  of bracket  28  extends downwardly for securing a panel  42 , which is discussed below. Once the brackets  28  have been installed to the upper surfaces of the base members  22 ,  24 , a layer of insulating material  26 , such as polyiso foam board or polyisoboard, is secured atop each of the base members  22 ,  24 . Polyisoboard is typically constructed of polyurethane material and has a density of between about 2 to about 6 pounds per cubic foot. It is preferred that the more dense polyisoboard is applied beneath portions of the floor that support heavy equipment due to the increased structural strength and stiffness of the more dense polyisoboard. However, it is desirable to user less dense polyisoboard where possible, as the thermal insulative value of the polyisoboard decreases as a function of increased density. Preferably, an adhesive layer  34  is applied to at least one corresponding surface between the base member  22 ,  24  and the insulating material  26  to secure the base member  22 ,  24  and the insulating material  26  together. Alternately, a layer of tape having an adhesive layer  34  applied to each opposed surface of the tape can be used to secure the base member  22 ,  24  to the insulating material  26 .  
         [0028]     Once the base member  22 ,  24  has been secured to the insulating material  26 , skin  38  is then applied atop the insulating material  26 , such as by adhesive layer  34 , which can include a tape as previously discussed. In other words, mechanical fasteners are not required to secure the skin  38  to the insulating material  26 , which eliminates the need to form apertures in the skin  38  to receive the mechanical fasteners. Alternately, a material, such as a bonding agent, which may be distinguished from an adhesive, can be applied between the insulating material  26 , skin  38  and base member  22 ,  24  to provide a structural bond between the insulating material, skin and base member. As a result, although liquid can condense on the skin  38 , there is no risk of leakage of the condensed liquid through the skin  38 . Moreover, since the insulating material  26  prevents physical contact between the skin  38  and the base members  22 ,  24 , there is no path of substantially reduced thermal insulative properties between the skin  38  and the base members  22 ,  24 . Without the insulating material  26 , a path of substantially reduced thermal insulative properties between the skin  38  and the base members  22 ,  24  otherwise occurs, as skin  38  and the base members  22 ,  24  are constructed of metal.  
         [0029]     It is to be understood that metal fasteners that penetrate the skin  38 , insulating material  26  and the base members  22 ,  24  provide a path of substantially reduced thermal insulative properties.  
         [0030]     Similarly, as shown in  FIG. 3 , wall panels  42  assembled along the periphery of the base  20  do not provide a path of substantially reduced thermal insulative properties between the panels  42  and the base members  22 ,  24 . The construction of the panels  42 , which is described in an application titled “PANEL CONSTRUCTION FOR ΔN AIR HANDLING UNIT” is hereby incorporated by reference in its entirety. To secure panel  42  to base  20 , an edge of panel  42  is directed into contact with insulating material  26  abutting an upper surface of I-beam  22 . Preferably, an adhesive layer  34  is applied to at least one corresponding surface between the panel  42  and the insulating material  26  to secure the panel  42  and the insulating material  26  together. Alternately, a layer of tape having an adhesive layer  34  applied to each opposed surface of the tape can be used to secure the panel  42  to the insulating material  26 . Additionally, skin  44  of the panel  42  includes a flange that extends past the body of the panel  42  and abuts leg  32  of bracket  28 . Leg  32  and the flanged skin  44  are secured, such as by a mechanical fastener  50 . An opposite skin  45  of panel  42  which is separated from skin  44  by insulating material  46  and a vertically disposed insulating material  26 , is secured to the insulating material  26  by an adhesive layer  34  as previously discussed. Preferably, the surface of skin  45  facing away from insulating material  26  is secured to flange  40  of the skin  38 . Therefore, as further shown by  FIG. 3 , peripheral flange  40  and skin  45  are thermally isolated from skin  44  by insulating material  46 .  
         [0031]     Referring to  FIG. 4 , skin  38  is further thermally insulated by a layer of insulating material  52 . Preferably, prior to application of insulating material  52 , such as sprayed on or injected polyurethane foam, base  20  is inverted. Preferably, a sufficient quantity of insulating material  52  is applied to at least cover brackets  36 . In one embodiment, bracket  36  includes a leg  54  that extends substantially perpendicular from skin  38  which further extends to a leg  56  that extends substantially parallel to the skin  38 . Optionally, leg  56  further extends to a flange  58  that extends toward the skin  38 . Leg  54  is secured to the skin  38  by welding or other known bonding technique that does not form an opening through the skin  38 . Thus, even when multiple skins are assembled to form the skin  38 , such as by an overlap  65  of adjacent portions of the skin  38 , since the skin  38  is bonded along the seam of the overlap  65 , no condensed liquid forming on the upper surface of the skin  38  can leak through the skin  38 .  
         [0032]     Brackets  36  are preferably disposed so that there is an overlap  62  between leg  56  and a portion of a horizontal leg  60  of a base member, such as C-channel  24 . Since bracket  36  is formed into short lengths, such as about 2-4 inches, it is possible to inject insulating material  52  to substantially fill the entire region between the skin  38  and leg  56  of bracket  36 , including overlap  62 . As a result, due to the stiffness of the insulating material  62 , the overlap  62  between leg  56  of bracket  36  and the horizontal leg  60  of the base member  22 ,  24  provides structural stability to the skin  38 , especially when the skin  38  is subjected to a negative pressure environment during operation of the AHU.  
         [0033]     A negative pressure environment is encountered when the level of atmospheric pressure acting on the upper surface of the skin  38  is less than the level of atmospheric pressure acting on the lower surface of the skin  38 . In other words, in a negative pressure environment, the skin  38  is urged away from the base member  22 ,  24 . To counteract this effect, insulating material  52  disposed in the overlap  62  between leg  56  and leg  60  is compressed during this negative atmosphere pressure to resist movement of the skin  38  away from the base member  22 ,  24  caused by exposure of the skin  38  to the negative pressure. The length and number of brackets  36  required depends upon the stiffness of the foam material as well as the anticipated level of negative pressure and the amount of surface area of the skin  38 . Thus, the bracket length can significantly deviate from the preferred 2-4 inch length range. Additionally, the length of the legs  54 ,  56 ,  58  are not necessarily the same dimension. By making use of the overlap  62 , through fasteners are avoided which provides a skin  38  having no through metal connections extending from the base members  22 ,  24  to the skin  38 , enhancing the thermal insulative properties of the base  20 .  
         [0034]     In an alternate construction as shown in  FIG. 5 , and which can be used in combination with bracket  36 , bracket  136  may need to be arranged adjacent to a horizontally disposed leg of a base member  22 ,  24 . In other words, bracket  136  may not require an overlap  62  with base members  22 ,  24 . As shown, bracket  136  includes a leg  138  extending substantially perpendicular to the floor skin  38  that further extends to a leg  140  that is disposed substantially parallel to the skin  38 . The legs  138 ,  140  of bracket  136  define a pair of channels  142  into which an amount of insulating material  52  is disposed. The efficacy of bracket  136  depends upon the structural properties of the insulating material  52  to resist movement of bracket  136  away from the base members  22 ,  24 , which is akin to retrieving an anchor suspended in a sheet of ice.  
         [0035]     It is to be understood that brackets  36 ,  136  can include any construction that includes a leg or legs extending away from the skin  38  that overlaps a portion of a base member  22 ,  24 . In the alternative, brackets  36 ,  136  can include any construction having a leg or legs extending away from the skin  38  that defines at least one channel  142  between the bracket  36 ,  136  and the skin  38 .  
         [0036]     An alternate construction of the base is shown in  FIG. 6  wherein the horizontal leg  60  of the base member  24  supports insulating material  26  and a structural member, such as a tube  66 , that overlies the insulating material  26 . Tube  66  is in contact with and supports the floor skin  38 . Adhesive layers  34 , which can include a bonding material or a tape as previously discussed, is used to secure skin  38 , tube  66  and base member  24  at least temporarily until insulating material (not shown in  FIG. 6 ; see  FIG. 4 ) is applied. By avoiding the metal-to-metal contact between fastener  64  and tube  66 , there can also be no metal-to-metal contact extending from the floor skin  38  to the base member  24 . Preferably, tube  66  is disposed beneath a seam  70  formed between adjacent edges of sheets of floor skin  38 , the seam preferably being welded together to provide a fluid tight seal. By positioning tube  66  in contact with the floor skin  38 , not only does the tube  66  protect the insulating material  26  from damage resulting from the welding operation to the seam  70 , but the same welded seam  70  additionally welds the tube  66  to the seam  70 , providing an efficient technique to simultaneously bond the floor skin  38  edges and the tube  66  in a single bonding process.  
         [0037]      FIG. 7  shows a base construction in which two separate base subassemblies  108  can be assembled together along a common juncture  82 . This separable joint is typically referred to as a split, since the AHU may be required to be assembled into smaller portions for shipping purposes. Each subassembly  108  includes structural support of the floor skin  38  by horizontal legs  60  of base members  24 . Horizontal legs  56  of brackets  36  form overlaps  62  with respective portions of horizontal legs  60  to secure floor skin  38  as previously discussed. A pair of angles  76  are disposed adjacent the juncture of the base assemblies  108  with vertical legs  80  preferably being disposed coincident with the juncture  82  so that when the base subassemblies are brought together, surfaces of the vertical legs  80  are in mutual conformal contact. Preferably, removable fasteners  84  used to secure the adjacent vertical legs  80  together are disposed adjacent to the upper ends of the vertical legs  80  to permit condensation to collect on the floor skin  38  to a desired depth that is below the position of the apertures formed in the vertical legs  80  necessary for mounting the fasteners  84 . The horizontal legs  78  are preferably secured to the floor skin  38  by welding, so that the angle  76  forms a fluid tight seal with the floor skin  38 . In other words, as shown in  FIG. 7 , each subassembly  108  defines a fluid tight seal between the floor skin  38  and the respective angle  76  extending along the perimeter of each subassembly capable of collecting an accumulation of condensation above the floor skin  38  to a depth corresponding to the location of the fastener apertures formed in vertical legs  80  of the angles  36 . Alternately, it is possible to secure the vertical walls  80  together with a clamp, so that no apertures are formed in the vertical walls.  
         [0038]     It is to be understood that the construction as shown in  FIGS. 6-9  also include application of insulating material  52  (see  FIGS. 4 and 5 ) that is not shown for clarity of showing features of the base construction of the present invention. That is, for example, in  FIG. 9 , insulating material applied to the underside of the floor skin  38  flows into gap  104  and under angles  54  that similarly overlap corresponding horizontal legs of structural members, e.g., base member  24 , so that the floor skin  38  remains in position when the floor skin is subjected to a negative pressure.  
         [0039]     An alternate wall panel  242  construction as shown in  FIG. 8  includes a structural member  84 , such as a C-channel, having a web  86  disposed between opposite legs  88 ,  90 . An adhesive layer  34 , which can be in the form of tape having adhesive applied to each of the opposed surfaces of the tape, is disposed between each of legs  88 ,  90  and insulating material  26 . The surface of insulating material facing away from structural member  84  is bonded to a surface of respective skins  44  by additional adhesive layers  34 . In other words, panel  242  can be assembled without mechanical fasteners, which are typically constructed of a material, i.e., metal, having a low thermal insulation value, that would otherwise lower the insulating efficiency of the wall panel  242  by providing a continuous path of substantially reduced thermal insulative properties between opposed skins  44 . The region defined by the opposed skins  44  and structural members  84  (one structural member  84  not shown for clarity in  FIG. 8 ), is filled with insulating material  46  as previously discussed.  
         [0040]     An alternate base construction is shown in  FIG. 9  includes use of a base member  22  in the form of a C-channel instead of an I-beam along the perimeter of the base, wall panel  242  and the alternate base construction shown in  FIG. 6 .  FIG. 9  shows one side of the base construction, wherein base member  22  forms one side of the base support, and one of the plurality of transversely disposed base members  24  that are secured to the base member  22 , preferably by welding. To prevent damage to the insulating material  26  supported by horizontal leg  60  of base member  24  that would otherwise be damaged by welding the horizontal leg  60  to the base member  22  (and additional welding described below), the tube  66  and insulating material  26  are trimmed short of flush with the edge of base member  24  as indicated by gap  104 . Floor skin  38  does not need to be trimmed. The wall panel  242  rests upon insulating material  26  that is secured to the upper surface of horizontal leg  23  of base member  22 . An angle  98  has a horizontal leg  100  that is secured to the floor skin  38 , preferably by welding, to preferably achieve a fluid tight seal therebetween. Preferably, the length of horizontal leg  100  is less than the gap  104  to prevent damage to the insulating material  26  during the welding process for securing horizontal leg  100  to the floor skin  38 .  
         [0041]     A vertical leg  102  of the angle  98  is positioned to contact the facing surface of skin  44  of the wall panel  242 . Contacting corresponding surface of the opposite skin  44  of wall panel  242  is a vertical leg  96  of angle  92 . A horizontal leg  94  of angle  92  is secured to the lower surface of leg  23  of base member  22  to better secure wall panel  242 . To secure wall panel  242  in position, a removable fastener  106  can be directed through the vertical leg  102  of angle  98  and into wall panel  242 . Preferably, the location of fastener  106  is above a predetermined maximum desired level of condensation that can be collected by the floor skins and angles  98 . In other words, the aperture formed in the vertical leg  102  is above the fluid level reached when a predetermined maximum desired level of condensation is collected in the base construction of the present invention. It is to be understood that although structural support members are shown as C-channel or I-beam, these members could also be of any other geometry capable of supporting the floor skin and wall panels.  
         [0042]     It is also to be understood that the structural support members could also be of any other geometry capable of supporting the floor skin and wall panels so long as the construction is configured to prevent a continuous path of substantially reduced thermal insulative properties between the structural support members and the floor skin. Additionally, although the insulating material is shown as being contiguous, i.e., single, continuous, unitary construction, the insulating material can also be provided in a discontinuous fashion, such as a plurality of segments of insulating material.  
         [0043]     It is to be understood that the base construction of the present invention could include only the arrangement as shown in  FIG. 9 , i.e., not include structural members  22 , only structural members  24 . Alternately, the base construction could only include structural members  22  if desired.  
         [0044]     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.