Abstract:
Heat insulation blanket ( 10 ) includes a layer of inner cells ( 16 ) containing a phase change material, and opposed outer cells ( 18  and  19 ) containing dead air or other undisturbed gas. When placed in an attic or other insulated area, the phase change material changes phase when the outside atmospheric temperature passes the phase change temperature, resulting in a delay in the transfer of heat between the interior space and the atmosphere because of the heat required for or given up by the PCM during its change of phase. The outer plies of sheet material that form the superposed cells of the cell blanket are formed with a coating of heat reflective material that faces the interior of the cell blanket, whereby the reflective surfaces are protected against deterioration and retain their capacity to reflect radiant heat.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part of U.S. patent application Ser. No. 10/056,730, filed Jan. 25, 2002, entitled “Reflective Heat Insulation.” Also, applicant claims the benefit of U.S. patent application serial No. 60/345,770, entitled “Blanket Insulation with Reflective Sheet and Air Space,” filed in the U.S. Patent and Trademark Office on Jan. 4, 2002. 
    
    
     FIELD OF THE INVENTION 
     This invention involves heat insulation for building structures whereby the walls, roof, ceiling, floors and other partitions of the building are insulated with flexible sheets of heat insulation material. More particularly, this invention involves heat insulation material that utilizes, in various combinations, phase change material, heat reflective material, dead air space, and fibrous blanket material, for use alone or in combination with other heat insulation materials in a building structure, to retard the transfer of heat between adjacent spaces about a building structure. Also, the method of making cell blanket heat insulation with a layer of phase change material is disclosed. 
     BACKGROUND OF THE INVENTION 
     Heat insulation material placed in walls, ceilings, roofs, floors and other areas about a building typically comprise fibrous blanket insulation, such as elongated blankets formed of fiberglass. The principle of the blanket insulation is to form dead air spaces that provide insulation against convection and conduction heat transfer. The blanket insulation can be formed in small “clumps” and blown into spaces such as into the attics of residential homes and other areas about building structures, and also can be made into elongated blankets formed in a specific width and thickness that are suitable for placement between parallel joists, studs, rafters, purlins and other parallel support structures that are uniformly spaced apart. The elongated blanket, such as a fiberglass blanket, usually is supplied in reels and is cut to the desired length at the job site for placement between the parallel structures. 
     Fiberglass is one of the more desirable materials for forming blanket insulation because it holds its shape and traps a substantial amount of air between its fibers to form the dead air spaces. However, the fiberglass alone does not provide adequate heat insulation against radiant heat transfer. 
     In the recent past, an additional sheet of radiant heat reflective material has been applied in building structures, sometimes in combination with other materials such as blanket material. The reflective material, such as aluminum foil, functions as a reflective surface for reflecting radiant heat, thereby functioning as a barrier to radiant heat transfer, and enhancing the insulation capabilities of the other heat insulation materials. 
     One of the problems with the above noted heat reflective insulation is that when reflective surfaces of the heat reflective foil engage another surface, such as an adjacent layer of insulation material or the structure of the building, the foil loses at least some of its ability to reflect heat. A space, such as a dead air space, must be maintained adjacent the foil in order for the foil to function as an effective heat reflector. 
     Another problem with the use of reflective surfaces in combination with other insulation materials for heat insulation is that if the surface of the reflective sheet material should become dirty from an accumulation of dust, trash, fibers, vapor, etc., the reflective sheet loses its ability to reflect radiant heat, and therefore loses its insulation value. 
     Another insulation innovation that has been developed in the recent past is the use of phase change material (“PCM”) in combination with other insulation materials. The PCM loses heat when it changes phase from a liquid to a solid and absorbs heat when it changes phase from a solid to a liquid. These changes of phase occur at a substantially constant temperature for the PCM. The net result is that when the PCM is used in a roof structure, for example, and the outside temperature begins to rise to a level higher than the phase change temperature, the PCM will remain at its phase change temperature as the PCM changes phase from a solid to a liquid. In the meantime, the PCM absorbs heat from the outside, warmer atmosphere without changing its own temperature or influencing a change of temperature in the inside atmosphere of the building structure. This effectively delays the transfer of heat from outside to inside of the building structure, reducing the load to be carried by the conventional air conditioning system of the building structure. 
     Likewise, the reverse is true when the outside temperature becomes lower than the phase change temperature of the PCM. The PCM begins to change phase from liquid to solid at a substantially constant temperature, gradually giving up its heat to the outside, cooler atmosphere, thereby delaying the transfer of heat from the warm interior of the building to the cooler outside atmosphere. 
     The use of PCM as an insulator for building structures is disclosed in U.S. Pat. No. 5,626,936, which is incorporated herein by reference. 
     Although the use of PCM has been disclosed in the prior art as being used as an insulator for building structures, the production and installation of insulators that include PCM is still somewhat expensive and not appreciated by most in the industry. 
     It is to these problems that this invention is addressed. 
     SUMMARY OF THE INVENTION 
     Briefly described, the present invention comprises an improved heat insulation assembly for placement in and for becoming a part of a building structure, for insulating the structure from conduction, convection and radiation heat transfer through the wall structures of the building. This includes vertical walls, ceilings, roofs, floors, and other partitions that separate the interior temperature controlled spaces from outside uncontrolled temperature spaces, generally referred to herein as “wall structures.” 
     In the disclosed embodiments, radiant heat insulation is used, either alone or in combination with other types of heat insulation. Also, phase change material (“PCM”) is used in combination with other heat insulation materials. 
     The radiant heat insulation includes heat reflective sheet material, such as radiant heat reflective metal foil, radiant heat reflective metalized plastic sheet material, and plastic material coated with reflective substances such as metal. More specifically, the reflective material can be formed of the group consisting essentially of metalized polyester, metalized polyethylene, metalized polyvinyl chloride, and metalized polypropylene. Typically, foil and other radiant heat reflective sheet materials are silver in color, or other efficient radiant heat reflective colors. The reflective surface of the sheet is maintained in a spaced relationship with respect to the next adjacent structure, and is enclosed in a space that protects the reflective surfaces of the reflective sheet from the accumulation of dirt, dust, insulation fibers, vapor and other things that are likely to occlude or diminish the reflective properties of the reflective surface of the reflective sheet. 
     In addition to reflective insulation, the invention includes use of phase change material in combination with the reflective material. Phase change material can be any material that changes between a liquid state and a solid state in response to the change in temperature, when the temperature rises across the phase change temperature of the PCM or decreases from a level higher than to a level lower than the phase change temperature of the PCM. PCM suitable for use can include calcium chloride hexahydrate, sodium sulfate, paraffin, Na 2 SO 4 .10H 2 O, CaCl 2 .6H 2 O, NaHPO 4 .12H 2 O, Na 2 S 2 O 3 .5H 2 O, and NaCO 3 .10H 2 O. 
     An example of the use of PCM as a heat insulator is when the PCM is placed in an exterior wall or attic of a building and the outside temperature rises from a level substantially lower than the phase change temperature of the PCM to a level substantially higher than the phase change temperature of the PCM. As the temperature exceeds the phase change temperature of the PCM, the PCM remains at the same temperature as it absorbs heat that causes the PCM to change phase from solid to liquid. This has the effect of delaying the transfer of heat from the warmer atmosphere to the cooler interior of the building. 
     In the reverse situation, the outside temperature decreases from substantially higher than to a level substantially lower than the phase change temperature of the PCM, and as the PCM is cooled, it gives up heat in response to its changing of phase from liquid to solid. Again, this delays the transfer of heat emitted from the interior of the building to the cooler atmosphere. 
     This invention includes a combination of heat reflective insulation and phase change insulation in the form of a cell blanket, whereby superposed cells of phase change material and of dead air space are formed by overlying sheets that include a surface of radiant heat reflective material, such as aluminum foil. 
     In one embodiment of the invention, the cell blanket is formed with an inner layer of PCM cells and opposed outer layers of dead air cells, with the dead air cells and the overlying sheets that form the cells providing both protection for the PCM cells and protection for the radiant heat reflective surfaces, so as to avoid occlusion of the reflectivity of the heat reflective surfaces. 
     Other arrangements of the cell blanket can be utilized, such as only a single layer of dead air cells adjacent a single layer of PCM cells, and other combinations of superposed PCM cells and dead air cells including the heat reflective surfaces. 
     The cell blanket described above can be used alone or in combination with various other insulation structures, such as gypsum board, fibrous blanket insulation, between the purlins of an industrial building, in new construction, and in old construction so as to supplement the previously applied or substitute for the previously applied insulations. 
     The cell blanket is formed in a continuous process by advancing multiple plies of sheet material into superposed relationship along a processing path with the plies of sheet material including a pair of juxtaposed inner sheets and a pair of outer sheets, with the inner sheets positioned between the outer sheets. The sheets are progressively connected together with a plurality of parallel seams in the sheets that extend along the processing path. The connection of the sheets can be made by the application of heated rollers against the superposed sheets, which fuses seams in the sheets that extend longitudinally of the path along which the sheets are advanced. The progressive connection of the four sheets forms inner channels between the inner sheets and outer channels positioned on the opposite sides of the inner channels. As the inner channels are formed, they are filled with phase change material, preferably in the liquid state. As the inner channels are filled with phase change material, the outer channels that straddle the inner channels are filled with gas, preferably air. Once the channels have been filled with PCM and gas, the work product is passed adjacent laterally extending rolls that divide the channels into discrete cells, forming an array of cells, with the cells filled with phase change material positioned between the cells filled with gas. This completes the formation of the cell blanket, by which layers of cells are formed, with at least one layer of cells including a PCM and other layers of cells being filled with gas. The radiant heat reflective surfaces of the sheets of material that form the cell blanket are positioned adjacent the dead air cells, and the space occupied by the dead air protects the reflective surfaces from the accumulation of dust, dirt, fiber, or moisture, and from engagement with other surfaces so as to avoid occlusion or deterioration of the reflective surfaces of the sheet. This tends to prolong the reflective life of the sheet material and, therefore, the capacity to function as radiant heat insulation. 
     Another feature of the invention is that the superposed layers of sheet material that form the cell blanket have a continuous coating of heat reflective material, so that the array of cells that extends across the length and breadth of a cell blanket form a substantially continuous layer of radiant heat reflective sheet material about the length and breadth of the blanket. 
     Preferably, the heat fused seams formed in the cell blanket that divide the cells from one another are relatively thin when compared with the length and width of the cells, providing a relatively large cell area in comparison with the area occupied by the seams between the cells. 
     In addition to the insulation offered by reflective sheet material and the PCM, the sheets that form the cells and the gas within then cells provide both convective and conductive heat insulation. 
     Preferably, the cell blanket is formed of support sheets that are of heat fusible material, such as polyester and polypropylene. In situations where the fusion of the layers of sheet material is not practical, adhesive bonding of the seams is possible. 
     Thus, it is an object of this invention to provide an improved heat insulation blanket for use in insulating adjacent spaces from each other, which includes layers of superposed cells, with the different layers of cells containing different insulation materials. 
     Another object of this invention is to provide an improved cell blanket for use in insulating wall structures and the like, and which includes layers of arrays of cells, with one layer of cells including a phase change material and another layer of cells including a different insulation material. 
     Another object of this invention is to provide an improved cell blanket for insulating wall structures and the like of a building, which includes superposed layers of cells, with one layer of cells including heat reflective sheet material facing a dead air space, and another layer of cells including another heat insulation material. 
     Another object of the invention is to provide a cell blanket that includes phase change material and heat reflective material, with both the phase change material and the heat reflective material being protected from contact by other objects. 
     Another object of this invention is to provide a method for expediently and inexpensively producing the cell blankets described herein. 
     Other objects, features and advantages of the present invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective illustration of the cell blanket. 
     FIG. 2 is a side cross sectional view of one of the cells of the cell blanket of FIG.  1 . 
     FIG. 3 is a side cross sectional view, similar to FIG. 2, but showing a cell of different configuration. 
     FIG. 4 is a side elevational view, in cross section, of a wall structure that includes the cell blanket of FIG. 1, together with other insulation materials. 
     FIG. 5 is a cross sectional view of the combination of the cell blanket of FIG.  1  and gypsum board. 
     FIG. 6 is a cross sectional view of an insulated ceiling, showing the cell blanket applied on top of blanket insulation. 
     FIG. 7 is a cross sectional view of a roof structure of an industrial building, showing the cell blanket applied beneath a fiberglass blanket to the purlins of the structure. 
     FIG. 8 is a cross sectional view of a roof structure of an industrial building, showing the heat insulation blanket placed between adjacent layers of fiberglass blanket insulation. 
     FIG. 9 is a perspective illustration, showing how the cell blanket is produced. 
     FIG. 10 is a schematic illustration of how the cells are closed after having been filled with PCM and gas. 
    
    
     DETAILED DESCRIPTION 
     Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several views, FIG. 1 illustrates the heat insulation blanket  10  that is employed for reducing heat transfer between adjacent spaces about a building structure. The heat insulation blanket, hereinafter referred to sometimes as the “cell blanket” includes, in this embodiment, a pair of superposed inner sheets  11  and  12  and a pair of superposed outer sheets  13  and  14 . The inner sheets  11  and  12  are positioned between the pair of outer sheets. The inner sheets  11  and  12  are bonded together and form inner cells  16 , and the outer sheets  13  and  14  are bonded to the inner sheets  11  and  12 , respectively, forming the outer cells  18  and  19 . 
     The material that makes up the superposed sheets or plies is formed of thermoplastic material, such as polyethylene or polypropylene, which can be fused at elevated temperatures. As shown in FIGS. 1-3, the cells of the cell blanket are formed in an array, with adjacent cells being divided from one another by intervening longitudinal heat fused seams  21  intersected by lateral heat fused seams  22 . With this arrangement, all of the plies of the cell blanket can have the same length and breadth, and the cells are formed by heat fusing all the plies together, as illustrated. 
     In the embodiment shown in FIGS. 1 and 2, the outer cells  18  and  19  are of substantially equal volume and thickness, whereas in the embodiment shown in FIG. 3, the outer cell  19 A is thinner and of less volume than the opposed outer cell  18 A. With this arrangement, the smaller dead air of cell  19 A permits more rapid heat transfer through cell  19 A than through cell  18 A. This means that the atmosphere adjacent thinner cell  19 A has more potential influence on the inner cell  16 A than the atmosphere adjacent larger outer cell  18 A. Because of this dissimilarity in the rate of heat transfer across cells  19 A and  18 A, cell  19 A will be placed adjacent the external environment of the building structure where the temperature change usually is greater than the temperature change of the interior environment. Therefore, the insulation substance in cell  16 A is more likely to respond first to the temperature adjacent outer cell  19 A than to inner cell  18 A. 
     Inner cells  16  of the cell blanket  10  are filled with PCM, such as calcium chloride hexahydrate, sodium sulfate, paraffin, Na 2 SO 4 .10H 2 O, CaCl 2 6H 2 O, Na 2 S 2 O 3 .5H 2 O, NaCO 3 .10H 2 O, NaHPO 4 .12H 2 O. Outer cells  18  and  19  are filled with gas, usually air, which is the least expensive. Other gases that can be used in the cells  18  and  19  are Argon, Freon, Nitrogen, Carbon Dioxide, Krypton, and Xenon. 
     FIGS. 4-7 show examples of different environments in which the cell blanket of FIG. 1 can be utilized. Specifically, FIG. 4 shows the cell blanket  10  positioned adjacent the interior gypsum board  25  of a building, and on the other side adjacent fiberglass blanket  26 . The blanket is positioned adjacent the exterior plywood or other structural sheet  28  and the exterior of the building would include a facade  30  formed of brick, etc. The cell blanket  10  of FIG. 4 is similar to that disclosed in FIGS. 1 and 2 of the drawing. Typically, the cell blanket  10  will be adhesively mounted to a facing sheet of the fiberglass blanket  26 . However, the cell blanket  10  can be attached with staples or other fasteners to hard surfaces such as the vertically extending studs (not shown in FIG. 4) of the wall structure, by inserting the fasteners through the seams  21 ,  22  of the blanket, so as to not puncture the cells of the blanket. In those instances where the fasteners must be inserted through the cells, it will be noted that a single fastener would rupture only a single laminate of cells, so that the adjacent cells would remain in their preferred heat insulation condition. 
     FIG. 5 of the drawing illustrates that the cell blanket  10  can be adhered to an adjacent board  32 , such as gypsum board, again either with adhesive as illustrated or with fasteners, as may be desired. 
     FIG. 6 illustrates the cell blanket  10  placed in the attic of a building structure, where fiberglass blanket  35  is positioned between adjacent joists  36  and  37  on top of the ceiling board  38 . The cell blanket  10  can be placed in this position during original construction or as supplemental insulation installed after the building has been occupied. 
     FIG. 7 illustrates the cell blanket  10  applied to the roof structure of an industrial building. The industrial building includes parallel purlins  40 , and hard panels of roofing material  41  applied to the purlins. Blanket insulation  43  is positioned between adjacent ones of the purlins  40 , and the cell blanket  10  is applied to the purlins beneath the insulation blanket. 
     The sheet material, or plies, that form the cells of the cell blanket  10  preferably are formed of polyester, polyethylene, polyvinylchloride, polypropylene and other conventional materials that can bear a metalized coating to form a reflective surface. The metalized surface, or laminate, can be applied to one side or to both sides of the sheet material so that both sides are heat reflective. 
     FIG. 8 discloses a roof structure of an industrial building which includes adjacent purlins  50  with roof panels  51  applied thereto. Cell blanket  10  is positioned between adjacent fiberglass blankets  52  and  53 . 
     It usually is desirable to have the PCM respond to the temperature of the environment as opposed to the inside controlled temperature of the building structure. Accordingly, to assure that the outside temperature reaches the PCM and that the PCM responds to the outside temperature, the value of heat insulation between the PCM and the outside environment should be less than the value of the insulation between the PCM and the inside environment. In those instances where the phase change temperature of the PCM is relatively close to the anticipated controlled temperature of the interior of the building structure, it might not be required to have a lower insulation value between the PCM and the outside temperature. This arrangement might depend upon the anticipated differences between the high temperature and the phase change temperature, and the low temperature and the phase change temperature. 
     In those instances where it is desirable to have less insulation value between the PCM and the outside environment, either the cell blanket of FIG. 3 can be utilized, or the cell blanket of FIG. 2 can be utilized with other layers of insulation, such as shown in FIG.  8 . FIG. 8 illustrates the upper fiberglass blanket  52  being thinner than, and therefore offering less insulation value than, the lower or interior blanket  53 . 
     FIG. 9 illustrates the process by which the cell blanket  10  can be produced. Multiple sheets or plies  61 ,  62 ,  63  and  64  are fed from their supplies and are advanced along a processing path in a downward direction as indicated by arrows  65 - 68 , respectively. Various guide rolls guide the sheets until they pass in superposed relationship between opposed gangs of longitudinal heated sealing wheels  70  and  71 . The wheels of the gang  70  are urged toward the wheels of the gang  71 , with the superposed plies of sheet material passing between the wheels. As the wheels make contact with the superposed plies of sheet material, they heat and fuse the sheet material, forming the longitudinal seams  21  in the sheets. This causes the formation of longitudinal pockets in the superposed sheets. 
     In the meantime, laterally extending sealing drums  74  and  76  are rotatable about their laterally extending axes  77  and  78  in the directions as indicated by arrows  79  and  80 , and the laterally extending ribs  81  of the sealing drum  74  register with the laterally extending ribs  82  of the sealing drum  76 . The sealing drums  74  and  76  are heated, and their ribs are heated, to a temperature that causes the superposed sheets advancing along the processing path to fuse in response to the contact of the ribs  81  and  82 . This forms the lateral seams  22  in the superposed sheets, closing the pouches into cells, as best illustrated in FIGS. 1,  2 ,  9  and  10 . 
     In the meantime, the laterally extending sealing drums  74  and  76  each include surface ports  85  that communicate with internal, longitudinally extending conduits  86  (FIG.  10 ), with the internal conduits opening through one end of each of the sealing drums  74 ,  76 . A vacuum shoe  88  is applied to the end of each sealing drum, and each vacuum shoe  88  is in communication with inlet of a blower  90  that draws air through the vacuum shoe and through the internal conduits  86  and surface ports  85  that register with the vacuum shoe. This induces an area of low pressure adjacent the surface of the laterally extending sealing drums, adjacent the superposed outer plies  13  and  14 , causing the outer plies to be moved away from the inner plies  11  and  12 . This lateral movement draws gas in between the outer plies and the inner plies, so that when the sealing drums fuse the superposed sheets together, dead air space will be formed between the outer plies and their respective inner plies, as illustrated in FIGS. 1 and 2. The gas that fills the dead air space will be air unless another gas is supplied at the area between the outer plies an the inner plies. 
     It will be noted that when the manufacture of the cell blanket has been completed, the inner cells  16  will be completely enclosed within the outer cells  18  and  19 , so that the inner cells are completely sealed from and shielded by the outer cells. Likewise, the dead air spaces or cells between the inner and outer plies protect the facing surfaces of the sheet material from obstruction by other objects, and from the accumulation of dirt, dust, fibers, vapor or other items that might tend to diminish the reflectivity of the sheet material. Thus, the heat reflectivity capacity of the sheets  11 - 14  that make up the cell blanket is preserved. 
     If desired, less than all of the sheets can bear a heat reflective surface. For example, the outer surfaces of the pair of inner sheets  11  and  12  can bear the reflective surfaces while the surfaces of the outer sheets  13  and  14  can be translucent. 
     The PCM is dispensed from a container  72  through conduits  73  downwardly through a control valve  71  and moves by gravity into the pouches formed by the longitudinal heated sealing wheels  70 . The PCM can be dispensed in either liquid or solid form, with liquid form preferred. Dispensing the PCM in liquid form is more likely to result in better control of the volume of PCM dispensed, and it is desirable to be able to adjust the volume of PCM being dispensed into the cells to vary the thickness of the cells or to dispense to larger or smaller cells, or to adjust for expansion and contraction of the PCM that is likely to occur during its change of phase. 
     Although preferred embodiments of the invention have been disclosed in detail herein, it will be obvious to those skilled in the art that variations and modifications of the disclosed embodiments can be made without departing from the spirit and scope of the invention as set forth in the following claims.