Abstract:
A support means or pad which is adapted to overlie an area to be thermally regulated. A plurality of microcapsules are dispersed within the support pad. The support means may be a porous pad or overlying layers of a mesh-type fabric. The fabric sheets include a series of channels which may be zig-zag in shape and are filled with a temperature stabilizing means, for example, a macroencapsulated phase change material. Suitable phase change materials are paraffinic hydrocarbons and water. In another aspect of the invention, the temperature stabilizing means is distributed within the support means in proportion to the underlying thermal load.

Description:
GOVERNMENT RIGHTS 
     This invention was supported by USMC SBIR Contract No. N00140-98-C-1461. The Government has certain rights in this invention. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to the field of thermal control by means of a pad containing a temperature control means such as a phase change material and more specifically products such as wraps and vests made therefrom. 
     BACKGROUND OF THE INVENTION 
     It is known to employ microencapsulated phase change materials for the purpose of temperature regulation. For example, microencapsulated phase change materials have been incorporated into fibers and fabrics, foams and coated surfaces to achieve temperature regulation. However, as microcapsules are small (generally less than 1.0 mm), their thermal capacitance (and therefore the ability to cool) is limited. Also, when incorporated into foams and fabrics, they tend not to breath very well and as a result, moisture can be trapped which reduces temperature regulation, comfort and thermal efficiency. 
     In addition, blocks of phase change material have been incorporated into a vest as disclosed in U.S. Pat. No. 5,415,222. The blocks are adapted to fit within pockets and provide a cooling effect to the wearer. However, due to the size of the blocks, the moisture tends to become trapped between the skin of the wearer and the inside of the phase change material block which becomes uncomfortable for the wearer and which reduces the thermal efficiency of the garment. Another drawback to the use of large blocks of phase change material is the lack of flexibility which limits applications. Paraffinic wax phase change material is also a good insulator and prevents heat from being conducted away from the inside surface next to the body to the rest of the block. 
     It is accordingly an object of the present invention to provide a micro-climate temperature regulating pad that overcomes the above noted problems associated with the prior art devices. 
     More particularly, it is an object of the present invention is to provide a micro-climate temperature regulating pad that has increased thermal regulation capacity. 
     Another object of the present invention is to provide a micro-climate temperature regulating pad that is flexible. 
     Still another object of the present invention is to provide a micro-climate temperature regulating pad that permits air circulation therethrough. 
     Yet another object of the present invention is to provide a micro-climate temperature regulating pad that is comfortable. 
     A further object of the present invention is to provide a micro-climate temperature regulating pad that is inexpensive and which is easy to form into useful articles of commerce. 
     A further object of the present invention is to provide a micro-climate temperature regulating pad that can compensate for uneven rates of thermal radiation across a surface. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a support means or pad which is adapted to overlie an area to be thermally regulated. A plurality of macrocapsules containing a phase change material (or PCM) are dispersed within the support means. The support means may be a porous pad or overlying layers of a mesh-type fabric. The fabric sheets include a series of channels which may be zig-zag in shape and are filled with a temperature stabilizing means, for example, a macroencapsulated phase change material. Suitable phase change materials are paraffinic hydrocarbons and water. 
     In another aspect of the invention, the temperature stabilizing means is distributed within the support means in proportion to the underlying thermal load. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Some of the features and advantages of the invention having been briefly stated, others will appear from the detailed description which follows, when taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a front view of the cooling garment according to the present invention. 
     FIG. 2 is a top view of vest cooling garment according to the present invention. 
     FIG. 3 is a cross section of a macrocapsule as employed in the present invention. 
     FIG. 4 is a side view of one of the channels taken along line  3 — 3  of FIG.  1 . 
     FIG. 5 is a schematic view of an alternate embodiment of the support means of the present invention. 
     FIG. 6 is a schematic view of an alternate embodiment of the vest according to the present invention showing a zipper or hook and loop fastener system for entering and exiting the vest. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the present invention will be described more fully hereinafter, it is to be understood at the outset that persons of skill in the art may modify the invention herein described while still achieving the favorable results of this invention. Accordingly, the description which follows is to be understood as a broad teaching disclosure directed to persons of skill in the appropriate arts, and not as limiting upon the present invention. 
     The reader will note that the present invention is described herein with respect to a vest type garment, however, it will be understood that most articles of clothing could be constructed, as well as protective wraps for humans, animals or commercial goods. In addition, the micro-climate temperature regulating pad according to the present invention will also be incorporated in many as yet to be determined applications. For the sake of simplicity of discussion only, the present invention will be described in the context of a wearable vest as shown in the accompanying drawings. 
     Referring more particularly to the drawings, the vest according to the present invention is there illustrated. It will be noted that in the embodiment that was constructed (and as referred to herein) the vest is adapted to cool the wearer. However, with the proper selection of phase change material, the vest could also be employed as a warming vest. 
     The garment  10  is adapted to cover the upper portion of the wearer&#39;s body, and it is effective to cool the wearer as will be more fully explained hereinbelow. 
     The vest comprises a generally rectangular sheet of flexible breathable material. The generally rectangular sheet has opposite end edges  11 ,  12  and opposite side edges  13 ,  14  and end edges  20 ,  21 . The sheet further includes an opening  15  in a medial location to define front and rear panels  16 ,  17  respectively on opposite sides of the opening  15  so that the sheet is adapted to be positioned on a wearer with the wearer&#39;s head extending through the opening and with the front and rear panels respectively overlying the chest and back of the wearer. The vest according to the present invention can also be constructed as a front opening garment, similar to the standard military flak jacket. In the aforementioned flak jacket, the two front sides are held together via a hook and loop fastener system (schematically shown) as shown in FIG. 6. A conventional zipper may also be employed. 
     As illustrated in the figure, the front and rear panels are formed from separate pieces of a fine mesh material such as NYLON® or polypropelene. For ease of entry, the panels are sewn together along one pair of contiguous edges that overlie one of the shoulders. The other pair of contiguous edges are adapted to be held together by means of hook and loop fasteners  18  positioned on the underside of the strap members  19  and  20  on the panels. The front and rear panels  16 ,  17  are adapted to closely conform to the shape of the wearer. Strap means or side straps  19  extend from the side edge  13  and are adapted to be connected to the side edge of the opposite panel, again by hook and loop fasteners (not shown). In this manner, the vest is provided with additional flexibility as depending on the waistline of the wearer, close conformity with the body of the wearer can be assured to maximize thermal transfer. 
     In the illustrated embodiment of the invention, the panels  16 ,  17  are formed from overlying sheets of fabric. A series of zig-zag or herring bone shaped channels are formed the panels. The channels may be formed by any of the conventional means compatible with the material used (i.e., stitching, fusion, etc.). The material is a relatively fine mesh type material wherein the mesh openings are small enough to contain the macrocapsules. The channels may be of varying width to accommodate differing quantities of macrocapsules. In addition, fabrics or pads have been developed wherein the bulk is obtained by an irregular or random distribution of fibers. Marcocapsules can be distributed within the interstitial spaces between the fibers such that they remain trapped therein. 
     It has been recently learned that different areas of the body radiate or transport heat at rates higher than others. More specifically, in areas where large blood vessels are closer to the surface (such as the head, chest and neck), more heat emanates from the body. In addition, it has also been discovered that heat radiates differently between men and women. The benefits and advantages of variable macrocapsule loading will be described in greater detail hereinbelow. 
     The macrocapsules comprise a glass or polymer shell that contains a temperature stabilizing means such as a phase change material. A macrocapsule  90  (generally greater than 1.00 mm in diameter) is illustrated in FIG.  4  and comprises an outer wall  92  and a phase change material filling. A number of phase change materials which have a cooling effect are available, but the paraffinic hydrocarbons are preferred since they are non-toxic, relatively inexpensive and can be contained within plastic films. The table below lists a number of bulk paraffinic compounds whose number of carbon atoms dictate where the material will change phase. 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 NUMBER 
                 MELTING 
               
               
                   
                   
                 OF 
                 POINT 
               
               
                   
                   
                 CARBON 
                 DEGREES 
               
               
                   
                 COMPOUND NAME 
                 ATOMS 
                 CENTIGRADE 
               
               
                   
                   
               
             
             
               
                   
                 n-Octacosane 
                 28 
                 64.1 
               
               
                   
                 n-Heptacosane 
                 27 
                 59.0 
               
               
                   
                 n-Hexacosane 
                 26 
                 56.4 
               
               
                   
                 n-Pentacosane 
                 25 
                 53.7 
               
               
                   
                 n-Tetracosane 
                 24 
                 50.9 
               
               
                   
                 n-Tricosane 
                 23 
                 47.6 
               
               
                   
                 n-Docosane 
                 22 
                 44.4 
               
               
                   
                 n-Heneicosane 
                 21 
                 40.5 
               
               
                   
                 n-Eicosane 
                 20 
                 36.8 
               
               
                   
                 n-Nonadecane 
                 19 
                 32.1 
               
               
                   
                 n-Octadecane 
                 18 
                 28.2 
               
               
                   
                 n-Heptadecane 
                 17 
                 22.0 
               
               
                   
                 n-Hexadecane 
                 16 
                 18.2 
               
               
                   
                 n-Pentadecane 
                 15 
                 10.0 
               
               
                   
                 n-Tetradecane 
                 14 
                  5.9 
               
               
                   
                   
               
             
          
         
       
     
     Each of the materials above is most effective near the melting point indicated above. It will be seen from the foregoing, that the effective temperature range of the vest can be tailored to a specific environment by selecting the phase change material(s) required for the corresponding temperatures and placing the phase change material therein. In addition, silica or other gels may also be employed. 
     As mentioned hereinabove, the macrocapsules are dispersed within a series of channel means or channels  30  formed in the vest panels. The channels  30  may be of any shape to accomplish the desired result (i.e., straight, circular, zig-zag, spiral, etc.) and still be within the scope of the invention. Notwithstanding the foregoing, when taken with respect to the illustrated embodiment, a zig-zag or herringbone pattern is preferred. This pattern permits the vest to flex sufficiently to conform to the shape of the person wearing it. In addition, such a shape minimizes packing or shifting of the particles which can cause “hot spots” (uneven heat absorption). 
     As briefly mentioned, thermal radiation or heat transport occurs from different parts of the body at different rates. Therefore, in order to cool those areas generating higher amounts of heat, the section of vest that overlies these areas can be loaded to contain more macrocapsules. With respect to the embodiment illustrated in FIGS. 1,  2 , and  4 , the channel width (i.e., the distance between parallel rows of stitching) is increased which permits increased macrocapsule loading. 
     In another aspect of the invention, it has been learned that air flow between the heat source and the environment extends the cooling effects of the vest. In addition, air flow around the macrocapsules aids in conduction of the heat out of and away from the heat source. The porous nature of the support means and the use of macrocapsules facilitate enhanced cooling. 
     In operation, the wearer places his head through the large medial opening in the vest overlying his shoulders. The side straps  19  are then tightened to provide a snug fit against the torso. Upon exertion by the wearer, perspiration is allowed to exit via the openings in the support means and through the interstitial spaces between the macrocapsules. 
     The foregoing embodiments and examples are to be considered illustrative, rather than restrictive of the invention, and those modifications which come within the meaning and range of equivalence of the claims are to be included therein.