Abstract:
An insulated sleeping bag insert constructed such that when used with a sleeping bag provides additional insulation thickness above and to the sides of the user, thereby extending the lower limit of the usable temperature range of the sleeping bag. The insert is fitted with attachment mechanisms that allow it to be attached and retained in position within the interior of the sleeping bag. The insulated sleeping bag insert construction is unique in that, in addition to a layer of uniform insulation over the sleeper&#39;s body, additional insulation-containing space fillers are incorporated into the sides of the insert to fill-in around the sleeper for reducing the internal volume of the bag.

Description:
FIELD 
     The present disclosure relates generally to sleeping bags and, more particularly, to a sleeping bag assembly including a sleeping bag and a thermally insulated insert installed within the sleeping bag for reducing the internal volume of the sleeping bag to extend the lower limit of the sleeping bag&#39;s usable temperature range. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Sleeping bags come in several different physical configurations including, but not limited to, rectangular, semi-rectangular and mummy. In addition, some sleeping bags may incorporate an integral hood. Typically, sleeping bags have one or more closure devices, such as zippers, to provide access to an entrance aperture and which can be located on the sides, ends or top to permit use of the sleeping bag. 
     Sleeping bags typically include first and second opposed halves defining a sleeping compartment therebetween and which are connected in such a way to define the entrance aperture at an entrance side or end of the sleeping bag. Each half of the sleeping bag includes an outer shell layer and an inner shell layer with an insulating material disposed and retained between these two layers. Insulation thickness depends on the coefficient of thermal conductivity of the insulation material and the minimum ambient air temperature that is expected to be encountered by the user. However, regardless of the type of insulating material and its coefficient of thermal conductivity, colder ambient air temperatures require that a greater thickness of insulation be used to keep heat loss from the user sufficiently low enough that the user does not become uncomfortable within the sleeping compartment. 
     In view of the above, most sleeping bags having a “usable” ambient air temperature range within which the user will remain comfortable. However, to facilitate the use of otherwise conventional sleeping bags in colder ambient air temperature conditions below the lower limit of its usable temperature range, a need exists to develop alternatives for reducing heat loss within the sleeping compartment. The present disclosure is directed to addressing the above-noted shortcomings of conventional sleeping bags and to providing a solution for extending the lower limit of the useable temperature range of conventional sleeping bags. 
     SUMMARY 
     It is an aspect of the present teachings to provide a thermally insulated, sleeping bag insert that can be secured within a sleeping compartment of a sleeping bag so that the sleeping bag can be used at temperatures lower than that for which it was originally designed. 
     It is another aspect of the present teachings to provide an ultra cold-weather sleeping bag assembly comprised of a cold-weather sleeping bag and a thermally insulated, sleeping bag insert. The thermally insulated insert is installed within the sleeping compartment of the sleeping bag and functions to extend the lower limit of the usable temperature range of the sleeping bag. 
     In accordance with these and other aspects, the present disclosure is directed to a sleeping bag insert configured to include a plurality of insulation containing compartments. The sleeping bag insert is generally configured such that there is a layer of insulation over the user&#39;s body and, in some cases, the insert may also include longitudinal space fillers located along each side that can function, under the influence of the insulating material, to expand inwardly and fill voids surrounding the user&#39;s body. A bottom portion of the sleeping bag insert may be constructed such that additional insulation is added in the foot area in the form of a foot box. A top portion of the insert may be constructed to fit over the shoulders and around the neck of the user so as to subdivide the sleeping compartment into two separate compartments. 
     Further areas of applicability will become apparent from the description and claims herein. The description and specific examples in the disclosure and summary are intended for purposes of illustration only and are not intended to limit the scope of the present invention. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected exemplary embodiments and are not intended to limit the scope of the present disclosure in any way. Similar or identical elements are given consistent reference numerals throughout the various figures. 
       Reference now will be made to the accompanying drawings in which: 
         FIG. 1  shows a perspective view of an exemplary sleeping bag adapted for use with a thermally insulated, sleeping bag insert that is constructed in accordance with the present disclosure to define a sleeping bag assembly; 
         FIGS. 2A and 2B  show cross-sectional views of exemplary differential and non-differential cut sleeping bags adapted for use with the thermally insulated, sleeping bag insert of the present disclosure; 
         FIG. 3  shows a perspective view of a thermally insulated, sleeping bag insert constructed according to the present teachings and configured with its upper part (the portion covering the upper body of the user) shown in an open or uncovered position while its lower part (the portion covering the legs and feet of the user) shown in a closed or covered position; 
         FIGS. 4A through 4E  show a series of different insulation retention chamber/tube configurations that may be used with the thermally insulated, sleeping bag inserts of the present disclosure; 
         FIGS. 5A and 5B  show a perspective view and a sectional view, respectively, of a thermally insulated, sleeping bag insert generally similar to that shown in  FIG. 3  and incorporating the teachings of the present disclosure; 
         FIGS. 6A and 6B  show a perspective view and a sectional view, respectively, of a thermally insulated, sleeping bag insert constructed according to an alternative embodiment and incorporating the teachings of the present disclosure; 
         FIGS. 7A and 7B  show a perspective view and a sectional view, respectively, of a thermally insulated, sleeping bag insert constructed according to yet another alternative embodiment and incorporating the teachings of the present disclosure; and 
         FIGS. 8A through 8C  illustrate longitudinal and transverse cross-sectional views through the sleeping bag assembly with the thermally insulated, sleeping bag insert attached and retained within the sleeping bag according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of the various exemplary embodiments is provided so that the present disclosure will be thorough and fully convey the scope to those skilled in the art. Numerous specific details are set forth such as examples of specific components, devices and schematic configurations to provide a thorough understanding of each of exemplary embodiments of the present disclosure. However, it will be apparent to those skilled in the art that these specific details need not be employed, that the exemplary embodiments shown may be embodied in many different forms, and that neither should be construed to limit the scope of the present disclosure. 
     Referring primarily to  FIG. 1 , a perspective view of an exemplary cold-weather sleeping bag  10  having an integral hood  23  is shown in a partially open position, and which may be constructed to include an entrance end, denoted generally by reference numeral  11 . Sleeping bag  10  is generally conventional in construction and, as will be detailed below, is adapted for use with an insulated sleeping bag insert  100  (see  FIG. 3 ) to define an ultra cold-weather sleeping bag assembly  102  (see  FIGS. 8A-8C ). Entrance end  11  corresponds to the end of sleeping bag  10  which is intended to receive a user&#39;s head and upper body while a lower end  13  corresponds to the end of sleeping bag  10  intended to receive a user&#39;s legs and feet. Sleeping bag  10  is generally shown to include an outer shell  12 , an inner shell  14 , and a closure device such as, for example, a zipper assembly  16 . An insulating material  18  having a low coefficient of thermal conductivity and good compressibility is inserted and retained between outer shell  12  and inner shell  14 . Suitable insulating material may include, but are not limited to, water fowl down, polyester, etc. As is conventional, light-weight fabrics, such as nylon and polyester, may be used for the exterior surfaces defined by outer shell  12  and the interior surfaces defined by inner shell  14 . 
     Sleeping bag  10  has a first or upper half  15  and a second or lower half  17  arranged in opposing facing relation so that first half  15  and second half  17  are configured to define a first or primary sleeping compartment  19  therebetween when zipper assembly  16  is closed. First half  15  and second half  17  can be continuous to define a folded longitudinal edge portion or, as shown, they can be interconnected by a longitudinally extending seam or hinge  25 . Second half  17  is adapted to rest on the ground, or tent floor, cot, or on an insulating pad laying on the ground, tent floor or cot. 
     Sleeping bag  10  may further includes a plurality of insulation retention chambers  27 . Sleeping bag  10  is shown to include a plurality of circumferentially aligned retention chamber  27  formed in both of first half  15  and second half  17  that are delineated by seams and/or a baffle material. An elongated draft tube  22 , also filled with the insulating material, is located behind and in close proximity to zipper assembly  16  so to maintain an insulating thickness along the entire length of zipper assembly  16 . A drawstring  24  can be used in conjunction with a pair of draw hems  19  and  20  to adjustably vary a face opening in hood  23  at the top of sleeping bag  10  once zipper assembly  16  has been drawn to its closed position. A drawstring lock  21  is also provided to maintain drawstring  24  in a preferred cinched position. A pair of first insert attachment devices such as, for example, first zipper halves  28  are attached to opposite sides of an inner surface  30  of inner shell  14  of exemplary cold-weather sleeping bag  10  to facilitate the attachment of sleeping bag insert  100 . Zipper halves  28  can be installed upon initial fabrication of sleeping bag  10  or, alternatively, may be subsequently attached to portions of sleeping bag  10 . As will be appreciated, alternative first attachment methods or arrangements for releaseably attaching sleeping bag insert  100  within sleeping compartment  19  of sleeping bag  10  may be used and can include for example, and without limitation, loop and pile (e.g., Velcro®), snaps and buttons, etc. 
       FIG. 2A  shows the cross-section of an exemplary cold weather, side-zippered sleeping bag  10  fabricated using a “differential” cut construction wherein the circumference of inner surface  30  of inner shell  14  is less than that of an outer surface  32  of outer shell  12  along the full length of sleeping bag  10 . Draft tube  22  is shown located behind zipper assembly  16  within sleeping compartment  19 . As noted, insulating material  18  having a low coefficient of thermal conductivity and good compressibility is inserted and retained between outer shell  12  and inner shell  14  within retention chambers  27  as well as within draft tube  22 . The pair of first zipper halves  28  are shown mounted to opposite sides of inner shell  14  within the interior of exemplary cold-weather sleeping bag  10  to facilitate the attachment of insulated sleeping bag insert  100 . 
       FIG. 2B  shows the cross-section of an exemplary cold weather, side-zippered sleeping bag  10  fabricated using a “non-differential” cut construction wherein the circumference of inner surface  30  of inner shell  14  is approximately equal to that of outer surface  32  of outer shell  12  along the full length of sleeping bag  10 . Draft tube  22  is again positioned behind zipper assembly  16 . Again, insulating material  18  having a low coefficient of thermal conductivity and good compressibility is inserted and retained between outer shell  12  and inner shell  14  as well as within draft tube  22 . The pair of first zipper halves  28  are shown attached to opposite sides of inner surface  30  of inner shell  14  of exemplary cold-weather sleeping bag  10  to facilitate the attachment of insulated sleeping bag insert  100 . 
     Referring to  FIG. 3 , a perspective view of a thermally insulated, sleeping bag insert, hereafter referred to as insulated insert  100 , constructed according one exemplary embodiment of the present teachings is shown. As stated, the function of insulated insert  100  is to cooperate with sleeping bag  10  so as to extend the lower limit of the variable temperature range of sleeping bag  10 . An upper part  41  of insulated insert  100 , that is the part of insulated insert  100  adapted to cover the upper body of the user, is shown in an open or uncovered position. A lower part  42  of insulated insert  100 , that is the part of the insulated insert  100  that covers the legs and feet of the user, is shown in a closed or covered position. This view has been provided to clearly illustrate both an inner side portion  43  and an outer side portion  44  of insulated insert  100 . Insulated insert  100  is generally shown to include an outer shell  45  and an inner shell  46 . An insulating material  48  having a low coefficient of thermal conductivity and good compressibility is inserted and retained between outer shell  45  and inner shell  46 . A pair of second insert attachment devices such as, for example, second zipper halves  51  are shown attached to insulated insert  100  along the edges of outer shell  45 . Second zipper halves  51  are equal in length to the complementary first zipper halves  28  that are mounted to inner surface  30  of inner shell  14  of sleeping bag  10 . Engagement of complementary second zipper halves  51  with first zipper halves  28  is adapted to releaseably secure insulated insert  100  in position within sleeping compartment  19  of sleeping bag  10 . 
     An optional yoke  47  may be integrated into the upper end of upper part  41  of insulated insert  100 . Yoke  47 , like the main body portion of insulated insert  100 , includes an outer shell  45 ′ and an inner shell  46 ′ having an insulating material  48 ′ with a low coefficient of thermal conductivity and good compressibility inserted and retained therebetween. Yoke  47  defines a transverse portion having a neck aperture  47 A configured to surround the user&#39;s neck and shoulder area. An optional foot panel  49  may likewise be integrated into lower portion  42  of insulated insert  100 . Foot panel  49  can be configured to be equal in size to the inner foot portion of sleeping compartment  19  within sleeping bag  10 . Foot panel  49  is configured to partially close or totally encapsulate lower portion  42  of insulated insert  100  and is constructed to include an outer shell, an inner shell and an insulating material therebetween. 
     As will be detailed hereinafter with reference to  FIG. 4 , a plurality of internal baffle structures, generally identified by reference numeral  50 , are used to locate and maintain insulating material  48  between outer shell  45  and inner shell  46  within a plurality retention chambers  52  formed in insulated insert  100 . Retention chambers  52  can extend longitudinally and/or circumferentially along the length of insulated insert  100 . Baffles  50  can be attached to the insert&#39;s outer shell  45  and inner shell  46  by suitable means such as, for example, sewing or adhesives for delineating retention chambers  52 . 
       FIGS. 4A through 4E  show a series of different insulation retention chambers  52  that may be formed in insulated insert  100 . These tubes  52  may run transversely or longitudinally, or any combination thereof, relative to the length of insulated insert  100 . Chambers  52  are delineated between an outer shell material  53 , an inner shell material  54  and baffles  50  with the exception of the example shown in  FIG. 4E  where chambers  52  are formed by sewing or otherwise connecting outer shell material  53  directly to inner shell material  54  without the use of baffles  50 . As noted, insulation material  48  is inserted into compartments  52 . As will be appreciated, chambers  52  formed in insulation insert  100  can be configured differently than chambers  27  in sleeping bag  10  to optimize the positioning and amount of insulation material retained therein. 
     When use of insulated insert  100  is warranted due to extremely cold ambient air conditions, insert  100  is fitted into sleeping compartment  19  of sleeping bag  10  and retained therein by engaging each of second zipper halves  51  of insulated insert  100  with one of the complementary first zipper halves  28  of sleeping bag  10 . As noted earlier, other attachment methods such as loop and pile (e.g., Velcro®), snaps, buttons, etc. may also be used for the purpose of releasably attaching insulated insert  100  to inner shell  14  of sleeping bag  10 . 
     In accordance with another aspect of the present disclosure, insulated insert  100  may be constructed to include one or more insulation containing structures or compartments in addition to the insulation retention chambers  52  created between insert outer shell  45  and insert inner shell  46 . These additional insulated structures, hereinafter referred to as internal space fillers  60 , are integrated into body sleeping compartment  59  of insulated insert  100 . Referring primarily to  FIGS. 3 ,  5 A and  5 B, the features of insulated insert  100  will be better described in greater detail. Specifically, the circumference of an inner surface  62  of inner shell  46  is configured to be less than that of an outer surface  64  of outer shell  45  for the full length of insulated insert  100 . As noted, insulation material  48  is retained between outer shell  45  and inner shell  46  within retention chambers  52 . Retention chambers  52  are aligned to extend circumferentially. Space fillers  60  are defined or delineated by a spacer shell  61  and a portion of inner surface  62  of inner shell  46 . Space fillers  60  extend generally along the entire length of insert  100 . In addition, each space filler  60  is filled with an insulation material  63  disposed within the enclosed compartment or compartments therebetween. Insulation material  63  can be the same material or a different material than insulation material  48 . 
     Space fillers  60  may also contain one or more insulation retention chambers using baffling as previously described in  FIGS. 4A through 4E . Spacer shell  61  is preferably made of a material common to either outer shell  45  and/or inner shell  46  and which is suitably attached to inner surface  62  along its edges to define an enclosed compartment. The most efficient design would be to carry internal space fillers  60  along the entire length of insulated insert  100 . However, it is contemplated that alternative arrangements of one or more space fillers  60  along one or both side wall portions of sleeping bag insert  100  may be utilized. Second zipper halves  51 , as used in conjunction with first zipper halves  28  to retain sleeping bag insert  100  in sleeping compartment  19  of sleeping bag  10 , are also shown to be outboard of space fillers  60 . 
       FIGS. 6A and 6B  show an insulated sleeping bag insert  100 A which is generally similar to insulated sleeping bag insert  100  of  FIGS. 3 ,  5 A and  5 B and which also incorporates the teachings of the present disclosure. In particular, the circumference of inner surface  62  of inner shell  46  is again shown to be less than or equal to that of outer surface  64  of outer shell  45  along the full length of sleeping bag insert  100 A. As noted, insulation material  48  is retained between outer shell  45  and inner shell  46  within retention chambers  52 . Insert  100 A differs from insert  100  in that space fillers  60  are not used in this exemplary construction. Second zipper halves  51  are again used in conjunction with first zipper haves  28  to retain sleeping bag insert  100 A in sleeping compartment  19  of sleeping bag  10 . 
       FIGS. 7A and 7B  show a sleeping bag insert  100 B constructed in accordance with another alternative embodiment and incorporating the teachings of the present disclosure. In  FIGS. 7A and 7B , the circumference of inner surface  62  of inner shell  46  is less than or equal to that of outer surface  64  of outer shell  45  along the full length of sleeping bag insert  100 B. As noted, insulation material  48  is retained between outer shell  45  and inner shell  46 . Space fillers  60 ′ are now defined or delineated by spacer shell  61 , an internal baffle  65  and a portion  66  of outer surface  64  of outer shell  45 . Each space filler  60 ′ is filled with insulation material  63  disposed within the enclosed compartment or compartments therebetween. Baffle  65  is preferably made of material similar to baffles  50  or a material common to either outer shell  45  and/or inner shell  46  and which is suitably attached to inner surface  62  and outer surface  64 . As noted, space fillers  60 ′ may also contain one or more insulation retention chambers using baffling as described in  FIGS. 4A through 4E . Spacer shell  61  is preferably made of a material common to either outer shell  45  and/or inner shell  46  and which is suitably attached to inner surface  62  along its edges to define an enclosed compartment. The most efficient design would be to carry internal space fillers  60 ′ along the entire length of sleeping bag insert  100 B. However, it is contemplated that alternative arrangements of one or more space fillers  60 ′ along one or both side wall portions of sleeping bag insert  100 B may be utilized. Second zipper halves  51  are again used in conjunction with first zipper halves  28  to retain sleeping bag insert  100 B in sleeping compartment  19  of sleeping bag  10 . 
       FIGS. 8A through 8C  show longitudinal and transverse cross-sections through sleeping bag assembly  102  comprised of sleeping bag  10  and one of insulated insert  100 ,  100 A,  100 B constructed and retained within sleeping bag  10  according to the teachings of the present disclosure.  FIG. 8A  shows a longitudinal cross-section of sleeping bag  10  with sleeping bag insert  100  having with optional yoke  47  and foot panel  49  installed and retained according to the present disclosure. As noted, first half  15  and second half  17  of sleeping bag  10  are arranged in opposing facing relation so that first half  15  and second half  17  are configured to define a sleeping compartment  19  therebetween when zipper assembly  16  was closed. Accordingly, insertion of sleeping bag insert  100  into sleeping compartment  19  of sleeping bag  10  will cause sleeping compartment  19  to be subdivided into two compartments, a head sleeping compartment  58  and body sleeping compartment  59 . 
       FIG. 8B  shows a transverse cross-section of sleeping bag assembly  102  including a differential cut cold weather sleeping bag  10  and an insulated insert  100  attached to sleeping bag  10  using first zipper members  28  in conjunction with second zipper members  51 . This cross-sectional view clearly shows the additional insulation thickness gained by use of sleeping bag insert  100  above and to the sides of sleeping compartment  59 . In addition, this view also clearly shows that longitudinal space fillers  60  along each side that are cut full so that they can, under the influence of the insulating material, expand inwardly to fill voids surrounding the user&#39;s body. 
       FIG. 8C  shows a transverse cross-section of sleeping bag assembly  102  including a non-differential cut cold weather sleeping bag  10  and sleeping bag insert  100  attached and retained therein using first zipper members  28  in conjunction with second zipper members  51 . This cross-sectional view clearly shows the additional insulation thickness gained by use of sleeping bag insert  100  above and to the sides of sleeping compartment  59 . In addition, this view also clearly shows that the longitudinal space fillers  60  along each side that are cut full so that they can, under the influence of the insulating material, expand inwardly to fill voids surrounding the user&#39;s body.