Abstract:
This invention is related to ultra-light conduit for used air and a method for construction of such a conduit with sandwich sheet type of material such as “THERMO-FOIL™” permitting to avoid losses of heat and humid air. The method of construction of a used air rectangular conduit includes the following five (5) steps: 1) cutting of a sandwich sheet 2) sealing around the sandwich sheet 3) heat formation of lengthwise channels on the surface of sandwich sheet 4) assembling the sandwich sheet into a conduit of a predetermined length and 5) installing a lengthwise vertical reinforcement into the conduit and providing a male adaptor to a fore end of the conduit which could be adapted to an aft end of a joining conduit.

Description:
RELATED APPLICATION  
       [0001]    This application is a Continuation of U.S. patent application Ser. No. 08/547,131 filed on Oct. 24, 1995.  
     
    
     
       FIELD OF INVENTION  
         [0002]    This invention belongs to the field of exhausting used air from houses, apartments and commercial buildings and particularly from kitchen hoods, bathroom fans and dryer conduits.  
           [0003]    This invention is related to a new method of construction of used air conduits that have a circular or a rectangular cross section and made of a sandwich of reflective double wall air bubble cushioned material, such as “THERMO-FOIL ™” to prevent losses of heat and humid air.  
           [0004]    The method of construction comprises five steps of transformation of a sandwich sheet, for a rectangular conduit or for a conduit with a circular section. For a conduit with a rectangular section 1) cutting of a sandwich sheet, 2) sealing the periphery of the sandwich sheet 3) creating a heat formed channel installed lengthwise to deliminate four sides of a segment 4) assembling the mating ends of a sheet and 5) installing a male adaptor in one end of a segment for joining another end of a second segment.  
           [0005]    Another method of construction is provided for used air conduits with circular section by: 1) cutting a sandwich sheet 2) sealing around the sandwich sheet 3) passing through a bender to form a circular section 4) assembling the mating ends of a sheet and 5) putting a male adaptor to join another conduit.  
         PRIOR ART  
         [0006]    A review of prior art revealed some patents relating to conduits comprising insulating material, sheet type or foam type.  
           [0007]    The following patents held my attention.  
           [0008]    CN 2,049,198 Lutgen, Aug. 22, 1991, describes an insulator of the sandwich type conceived to exactly fit the internal shape of cryogenic containers. The sandwich includes successive layers of thermal insulating materials such as polystyrene and foams of different densities. To prevent liquid or gas exchanges, sheets must be enclosed in impermeable and rigid walls such as the steel walls of a cryogenic reservoir: this increases considerably the construction costs.  
           [0009]    CN 2,032,111 Cur et Al., Jun. 19, 1991, describes an insulator of the sandwich sheet type conceived to be stuck onto a flat face of a refrigeration unit. The sandwich, sealed at its ends, includes superposed lamellae made of different insulating materials and thin inter-lamellar spaces filled with air. The insulating sandwich of Cur et Al. is held by a wall of plastic and a wall of metal, this increasing considerably construction costs. Moreover, Cur et Al. do not show joints between sheets that would indicate how those could form independent structures without the existence of plastic and metal walls. Also Cur et Al. do not use air bubbles as a thermic insulation.  
           [0010]    U.S. Pat. No. 5,014,753 Rossignol et Al., May 14, 1991, describes a flexible and impermeable insulator to protect electrical wires against radiant heating. The insulator comprises a series of successive layers of polymers of which a first layer is of dark particles and a second clear with particles of metal having a reflecting surface. Rossignol et Al. do not use air bubbles as thermic insulation, nor the principle of hermetic joint around an empty structure.  
           [0011]    U.S. Pat. No. 3,810,491 Hildebrandt, May 14, 1974, describes a method of manufacturing insulating conduits of double-walling and circular section. Conduits of double walling comprise an interior pipe disposed in a coaxial way relatively to an exterior pipe and are insulated in the space comprised between double-walling. Insulators being constituted of many successive layers of insulating materials are separated by air spacing. These are obtained with an insulating method placing insulation in tension rather than compression. The insulating method consists in laying out insulating bands and spacers in a helicoidal way along the wall of the internal pipe and to remove the spacers to create a tension between the wall of the internal pipe and the wall of the external pipe. This invention requires two conduits with rigid walls. Its use seems less appropriate for bends or other brutal directional changes or for conduits of rectangular section.  
           [0012]    U.S. Pat. No. 3,397,720 Jones, Aug. 20, 1968, reveals an insulation system for cryogenic structures made of a sandwich sheet that has many successive layers of insulation material, such as sheets of corrugated polyester and other layers of insulation material. Sheets of corrugated polyester create space at the center leaving room for air. This application requires a double-walling pipe to avoid air losses through insulating sheets that seem porous. Moreover, this type of corrugated material, in the construction of sandwich sheets does not make them flexible enough for directional changes such as bends.  
           [0013]    Conventional used air conduits made for kitchen hoods are built with galvanized steel and do not comprise any insulation to prevent heat loss. This type of conduits is available on the market in two L-shaped half-conduits to be joined to make a rectangular conduit. The two parts are held together with ends that are not air tight and the conduits do not comprise any adaptor to hold the ends of conduits together, facilitating loss of humid air. This type of conduit does not comprise any thermic insulator, thus favoring humid air condensation in a conduit which passes through a cold area of a building or in winter time. So, as the conduit is not tight to fluid exchanges, humidity and condensing water may leak into the structure of the building and bring nuisances such as moisture or other problems needing repairs or replacement.  
           [0014]    None of the inventions mentioned above has a combination of a light material, not requiring rigid nor expensive walls, but on which the joints and the perimeter are air-tight, to prevent losses of warm and humid air.  
         Objectives  
         [0015]    The first objective of this invention consists in building vaportight used air conduits to prevent humid air losses in buildings, a thermic insulator to avoid humid air condensation within conduits, adaptors and means of joining such conduits.  
           [0016]    An objective of this invention is to provide a combination comprising a basic material with two external layers of a radiant material, separated by at least two layers of air bubbles comprised in between five films of plastic matter (as polyethylene), cut in variable sizes, prefolded in desired shape and assembled by means of adhesive bands and provided with rigid means of coupling at one end of a conduit and at the center of a four foot long straight conduit.  
           [0017]    Another object of this invention is to create ventilation conduits that are light, easy to install and at a lower cost than uninsulated conduits requiring the addition of an insulator available in present market.  
           [0018]    Another objective is to make four foot long conduits that permit union with multiangular bends or internal deflectors.  
           [0019]    The last objective is to make used air conduits of rectangular shape (10 inches×3¼ inches) for kitchen hoods, used air conduits of circular shape for bathroom (generally 3 inches) and drying-machine conduits (usually 4 inches).  
       
    
    
     DRAWING FIGURE  
       [0020]    I will describe hereinafter more precisely, a method of construction consistent with the present invention by referring to annexed drawings in which:  
         [0021]    [0021]FIG. 1 is a perspective view of a used air conduct, rectangular, with partial section.  
         [0022]    [0022]FIG. 2A is a plan view of the conduit of FIG. 1  
         [0023]    [0023]FIG. 2B is a side view of the conduit of FIG. 1  
         [0024]    [0024]FIG. 2C is a view from the upstream end of the conduit of FIG. 1  
         [0025]    [0025]FIG. 3A is a top view of a conduit, in construction  
         [0026]    [0026]FIG. 3B is a section according to line  3 B- 3 B of FIG. 3A  
         [0027]    [0027]FIG. 3C is a section according to line  3 C- 3 C of FIG. 3A, in assembly  
         [0028]    [0028]FIG. 3D is a close-up view of region  3 D of FIG. 3C in closed position  
         [0029]    [0029]FIG. 4A is a perspective view with a partial cut of a bend  
         [0030]    [0030]FIG. 4B is a perspective view with a partial cut of another bend  
         [0031]    [0031]FIG. 5 is a perspective view of a circular conduit with a partial section  
         [0032]    [0032]FIG. 6A is a partial section of a longitudinal junction of a circular conduit in preparation  
         [0033]    [0033]FIG. 6B is a partial section of the longitudinal joint of FIG. 6A completed.  
     
    
     DESCRIPTION OF THE INVENTION  
       [0034]    A preferred embodiment of the subject invention is illustrated in FIG. 1 wherein like parts refer to like numbers and which shows:  
         [0035]    Air Duct, Rectangular  
         [0036]    A rectangular air duct  20  particularly for evacuating used air has a parallelepiped shape and is made of a sandwich sheet  22 . The air duct  20  comprises a top  24 , a bottom  26 , a closed side  28  and an opened side  30  all forming a rectangular shape, parallel to the major axis  32  and in the direction of fluid flow. The air duct  20  also comprises opened upstream  34  and downstream  36  ends, it is also of rectangular shape and is parallel to a minor axis  38  and perpendicular to the fluid flow. The top  24  is joined to the closed side  28  with an adhesive band  40  on all the length of the top  24  and of the opened side  30 .  
         [0037]    A rectangular adaptor  42  comprises two longer sides  44  and two shorter sides  46 ; the rectangular adaptor  42  partly fits into downstream end  36  to serve as male end to another air duct on which the upstream end  34  serves as the female end.  
         [0038]    An elongated C-reinforcement  48  comprises a web  50  and two wings  52 . Each wing  52  of the C reinforcement is respectively in contact with the top  24  and the bottom  26 , the web  50  serving as support, the C-reinforcement  48  being near the center of the major axis  32  and of the minor axis  38 . The C-reinforcement  48  prevents the collapse of the top  24  onto the bottom  26 .  
         [0039]    [0039]FIG. 2A illustrates a view of the top  24  and of the rectangular adaptor  42 . FIG. 2B is a view of the opened side  30 , of the adhesive band  40  and of the rectangular adaptor  42 . FIG. 2C illustrates a view of the upstream end  34 , the rectangular adaptor  42  and the C-reinforcement  48 .  
         [0040]    [0040]FIGS. 3A, 3B and  3 C illustrate different steps of the construction of an air duct  20 , 4 foot long, 3¼ foot tall, 10 inch wide. FIG. 3A shows the result of the first step of construction, namely cutting the sandwich sheet  22  in such a way that it has a rectangular shape with a perimeter  54  comprising two sheet long sides  56  of 4 foot in length and two sheet short sides  58  of 30 inches.  
         [0041]    The second step of construction is that of sealing the perimeter  54  of the sandwich sheet  22  with a heated angle iron to form a first flat end  60  prolonging the opened side  30  and two lateral flat ends  64  prolonging the sheet short sides  58 .  
         [0042]    The third step of construction is that of creating V grooves  66  with a heated angle iron to form a first limit  68  between the top  24  and the closed side  28 , a second limit  70  between the closed side  28  et the bottom  26  and a third limit  72  between the bottom and the opened side  30 .  
         [0043]    [0043]FIG. 3B illustrates a detail of a side view of the sandwich sheet  22 , the first flat end  60 , the second flat end  62  and the V grooves  66  after the third step. The V grooves  66  have a 45° side  73  to form a isosceles triangle when the sandwich sheet is on a flat surface.  
         [0044]    The sandwich sheet  22  (FIG. 3D) is of THERMO-FOIL™ type and comprises an external film  74 , an internal film  76 , two layers of air cells  78 , the first flat end  60  (FIG. 3C) prolonging the top  24  and the second flat end  62  prolonging the opened side  30 . The air cells  78  act as insulators while the external film  74  and the internal film  76  act like radiant material to keep a gradient of temperature between ambient air and used air circulating in the air duct. There cannot be any heat loss between an environment with ambient air and an environment with used air because the first flat end  60  and the second flat end  62  seal a perimeter of the sandwich sheet  22 .  
         [0045]    [0045]FIG. 1 illustrates a wall located longitudinally relatively to a major axis parallel to the direction of fluid flow and of which a side is shown on FIG. 3C and presents a rectangular shape comprising a first end  88  extending in a first flat end  60  of a long crushed prolonged surface  80  of a width of 1½ inch, and a first angular crushing  82  at 45° relatively to the top  24 .  
         [0046]    A second end  89  extends in a second flat end  62  and comprises a second angular crushing  86  at 45° relatively to the opened side  30 . The second flat end  62  is crushed on a width of ½ inch and can comprise a small prolongated surface  84  that overhangs the second angular crushing  86 .  
         [0047]    [0047]FIG. 3C illustrates the fourth step of construction, namely to assemble the rectangular air duct  20 . When the sandwich sheet  22  is folded to form the air duct  20 , the first angular crushing  82  and the second angular crushing  86  join to make a corner of the air duct.  
         [0048]    The first flat end  60  located at the first end  88  is to be stuck to the outside of the opened side  30  and the second flat end  62  located at a second end  89  is to be stuck on the second crushing end  86  and on the small prolongated surface  84  on bottom  24  to form the air duct  20 .  
         [0049]    [0049]FIG. 3D illustrates a detail of the location of the first flat end  60  once assembled and held by the adhesive band  40 .  
         [0050]    The fifth step is that of fitting the rectangular adaptor  42  into the downstream end  36  and to fix the C-reinforcement  48  (FIG. 1) inside the air duct  20 .  
         [0051]    [0051]FIG. 4A is a perspective view of a vertical bend  90 , made for a ventilating network with a vertical change in direction.  
         [0052]    [0052]FIG. 4B is a perspective view of a horizontal bend  92  designed for a ventilation network with a horizontal change in direction.  
         [0053]    Circular Air Duct  
         [0054]    [0054]FIG. 5 is a perspective view of a circular air duct  100 , that has a cylindrical shape and made of a sandwich sheet  22 . The circular air duct  100  comprises a cylindrical wall  102  having a first end for circle  88 ′ and a second end for circle  89 ′ which are parallel to a major axis of circle  108 , an upstream and a downstream ends of circle  110  and  112 , opened and with circular sections, and a circular adaptor  114 .  
         [0055]    The first end for circle  88 ′ is joined to the second end for circle  89 ′ with an adhesive band for circle  116  on all the length of the circular duct  100 .  
         [0056]    The circular adaptor  114  is rigid, of cylindrical shape and comprises two ends  120 ; the two ends  120  being opened and comprising a circular section. The radius of the circular adaptor  114  is shorter than the radius of the circular section by an amount equal to the width of the sandwich sheet  22 . The circular adaptor  114  partially fits in the inside of the downstream end of circle  112  to serve as a male to a following air duct of which the upstream end of circle  110  is used as a female.  
         [0057]    To construct the circular duct  100 , having a length of 4 feet and a diameter of 3 or 4 inches, there are four steps equivalent to those needed to construct the air duct  20  with rectangular section. A first step consists in cutting the sheet  22  into a rectangular shape having a perimeter  54  (FIG. 3A) and two sheet long sides  56  of four feet and two sheet short sides  58  of 9½ or 12½ inches.  
         [0058]    A second step of construction consists in sealing the perimeter  54  of the sandwich sheet  22  with a heated angle iron to form a first flat end for circle  122  (FIG. 6A) prolonging the first end for circle  88 ′, a second flat end for circle  124  prolonging the second end for circle  89 ′ and two lateral flat ends for circle  126  prolonging the sheet short sides  58 .  
         [0059]    [0059]FIG. 6A shows a detail of the first end for circle  88 ′ that comprises a first flat end  122  that comprises a ½ inch wide prolongated external crushing and an angular side  130  angular relatively to the cylindrical wall  102 .  
         [0060]    The second side  124  prolongs itself towards the interior, over a width of ½ inch, and has a 135° side  134 .  
         [0061]    A third step of construction is that of assembling the circular duct  100 . The first flat end  122  is to be stuck outside of the second end  89  and the second flat end  124  is to be stuck under the first end  88  to form a continuous circular duct  100 .  
         [0062]    [0062]FIG. 6B illustrates the location of the first and second flat ends  122  and  124  with external and internal prolongations once assembled and enforced with an adhesive band  116 .  
         [0063]    A fourth step of construction is to put the sheet for the circular duct  100  through a bender to get a perfectly cylindrical product. This step is optional.  
         [0064]    A fifth step of construction is that of fitting the circular adaptor  114  into the downstream end  112 .  
         [0065]    I have discovered that the condensation problem caused by heat loss in used air conduit is resolved by using a sandwich sheet such as THERMO-FOIL™ with thermic insulation properties superior to those of foams or sandwiches made of lamellae of different insulating materials. I have also discovered that the problem of humid air loss caused by used air conduits that are not air-tight is resolved by sealing the perimeter at each joint by material of the sandwich sheet and in using an adaptor located judiciously in a used air system.  
         [0066]    The reflective sandwich sheet material is made of a sandwich comprising two layers of air cells and serving as thermic insulator and on which is superinposed on top and bottom a sheet of impermeable and radiant material.  
         [0067]    So the sandwich sheet may successively comprise an aluminum sheet, two layers of air bubbles contained within three films of a plastic sheet coated with a material that might be fireproof, and another aluminum sheet; or comprise an external aluminum sheet, a layer of air cells and an internal polyethylene sheet; or it might also be constructed with an external polyethylene sheet, a layer of air cells and an internal polyethylene sheet.  
       SUMMARY OF INVENTION  
       [0068]    A general objective is to create an air duct comprising a number of segments, each one longitudinally oriented relatively to a major axis  32  parallel to the direction of used air flow and comprising a wall delimiting an interior space which permits air flow, the wall being of uniform thickness and made of a rectangular sandwich sheet comprising air cells confined between a first external film and a second internal film, the second internal film coinciding with the wrapping of the internal space, each segment comprising an opened downstream end  36  and an upstream end  34 , and means for coupling fitted into the downstream end  36  to become the male end when joined with another segment, or to couple an used air conduit to a female end of another type of conduit, the upstream end being the female end receiving the above male end.  
         [0069]    The sheet may comprise: a first end  88  coinciding with the length of the rectangular sheet to form the longitudinal joint of the segment with a corresponding second end  89 , the first end terminating by a first 45° angular crushing  82  extended in a first flat end  60  and a second end  89  ending with a second angular 45° crushing  86  extended into a second flat end  62  that folds up onto the second angular 45° crushing  86 , the first 45° angular crushing  82  leaning on the second flat end  62 , the first flat end edge  60  settling onto the second end along the first external film. The wall comprises means of adhesion to seal and hold together the first and second ends.  
         [0070]    The coupling means comprise an adaptor  42  with an external face  43  adjacent to the second internal film  76  of the wall, partly extended outside of the downstream end  36  of the segment and that can be sled in the upstream end of an adjacent segment or series of segments. The wall also comprises lateral flat ends to seal sandwich material at upstream and downstream ends.  
         [0071]    The wall may also form a parallelepiped that has a rectangular section comprising a top  24  extended in the first flat end  60 , a closed side  28 , a bottom  26 , an opened side  30  extended by the second flat end  62  and at least three longitudinal folding lines of which one demarcating a first limit  68 , between the top  24  and the closed side  28 , another demarcating a second limit  70  between the closed side  28  and the bottom and a third one demarcating a third limit, between the bottom and the opened side, the parallelepiped comprising means of reinforcement orientated along the major axis, in contact with top and bottom, to prevent collapsing of the top onto the bottom.  
         [0072]    The rigid adaptor may be of parallelepiped shape and comprises two opened ends and a rectangular piece of length l and width w both inferior by twice the thickness t of the wall, relative to the length L and width W of the rectangular section of the segment, according to the equations L=2t+l and W=2t+w. The adaptor will lean against the internal side of an opening delimited by the top, the closed side, the bottom and the opened side of the segment.  
         [0073]    Means of reinforcement is a C shaped reinforcement comprising a web and two wings, each one respectfully touching top and bottom. The wings of the C are placed parallel to the major axis and the web serves as support.  
         [0074]    The first flat end is joined to the end of the opened side by means of adhesion located on the entire length of the opened side. Means of adhesion of the air duct is an aluminum band of the Mactac™ type located over the entire length of the wall, to join the first flat end to the second one.  
         [0075]    The wall may be cylindrical, in which case it comprises a first and second ends, the upstream and downstream ends being a circular section of radius R, means of coupling being a rigid adaptor comprising a cylindrical wall and two opened ends of radius r inferior by the amount of the thickness of the cylindrical wall, relatively to the radius of upstream and downstream ends, namely R=r+t.  
       Method of Construction  
       [0076]    The air duct may be made with rigid insulation material and involves the following steps:  
         [0077]    a step of cutting the sandwich of insulating material delimiting a perimeter of predetermined size.  
         [0078]    a step of sealing the perimeter to prevent fluid exchanges, gaseous or liquid, between the interior of the insulating material and the surroundings, the sealing step comprising a step of crushing the first and the second ends,  
         [0079]    a step of folding the sandwich around the major axis according to a desired shape,  
         [0080]    a step of assembling of the first and second flat ends by means of adhesives to complete the shape of the section,  
         [0081]    a step of installing of a rigid adaptor fitted into the downstream end.  
         [0082]    If the air duct is of parallelepiped form with a rectangular section comprising a top, a bottom, a closed and an opened sides, the method comprises these additional steps of construction:  
         [0083]    a step of folding by heating means the sandwich to obtain the angles, top, bottom, closed and opened sides required to have a rectangular air duct,  
         [0084]    a step of preparation of a C-reinforcement in making a web and two wings with the insulating material,  
         [0085]    a step of installation of the C wings respectively in contact with top and bottom, the web serving as reinforcement.  
         [0086]    The sandwich may be a sheet comprising many layers of material, four sides and a perimeter. The sealing steps of the perimeter consists in heating the perimeter with an angled-iron in such a way that the layers of the sandwich that form the insulation material melt to make four thin bands on each of the four sides of the sheet, of which two are respectively part of the first flat end of top and the second flat end of the opened side, the first flat end when installed, should be in front of the second flat end of the folded sheet.  
         [0087]    The width of the first flat end of the top is bigger than the width of the second flat end of the opened side so as to reinforce any joint between the top and the opened side, the first flat end of the top is installed, against the outside face of the opened side, the second flat end of the opened side being placed under the bottom face of the top side.  
         [0088]    The step of folding the sandwich consists in heating the sandwich with an angle iron so it will produce three V grooves within the wall of the sandwich. The V grooves having 135° sides form an isosceles triangle when the sandwich is flat on the ground: the V grooves respectively define a first limit between top and closed side, a second limit between closed side and bottom and a third one between bottom and opened side. When the sandwich is folded to built the rectangular air duct, the 135° sides are connecting, to create angles forming the rectangular air duct.  
         [0089]    A further assembling step consists in sticking the first flat end of the top against the outside of the opened side, with an adhesive band on all the length of the first flat end. Means of adhesives may be an aluminized adhesive band of the Mactac™ type installed on the full length of a joint, between the first and second flat end.  
         [0090]    The sealing step of the perimeter of the insulating material consists in heating the perimeter with a hot angle iron in such a way that the layers of the sandwich that form the insulation material melt to create a thin band and a 135° side, the first flat end with the 135° side  134  being set inside the cylindrical wall, the second flat end with the 135° angled side being set outside the cylindrical wall.  
         [0091]    The folding step requires an additional step of circulating the air duct with the assistance of a roll folding device. The second flat end  124  leans against the interior of the cylindrical wall to obtain a continuous cylindrical wall.  
         [0092]    The installation step comprises the jointing of a circular adaptor inside a downstream end, the adaptor being rigid and comprising a cylindrical wall and two ends.  
         [0093]    It is clear that the method of realization of the present invention being described above, referring to annexed figures is provided as an indication and not limiting. Modifications and adaptations may be made without parting with the objectives of the present invention.  
         [0094]    Other embodiments of the above invention are also possible and not limited to the scope of the following claims:  
                                             PARTS LIST                                    20   air duct           22   sheet           24   top           26   bottom           28   closed side           30   opened side           32   major axis           34   upstream end           36   downstream end           38   minor axis           40   adhesive band           42   rectangular adaptor           43   external face           44   longer side           46   shorter side           48   C reinforcement           50   web           52   wing           54   perimeter           56   sheet long side           58   sheet short side           60   first flat end           62   second flat end           64   lateral flat end           66   V groove           68   first limit           70   second limit           72   third limit           73   45° side           74   external film           76   internal film           78   air cell           80   long prolonged surface           82   first angular crushing           84   small prolonged surface           86   second angular 450               crushing           88   first end for rectangle           88 1     first end for circle           89   second end for rectangle           89 1     second end for circle           90   vertical bend           92   horizontal bend           100   circular duct           102   cylindrical wall           108   major axis of circle           110   upstream end of circle           112   downstream end of circle           114   circular adaptor           116   adhesive band for circle           120   ends           122   first flat end for circle           124   second flat end for circle           126   lateral flat end for circle           130   angled side           134   135° side