Abstract:
A sleeping bag constructed such that its outer circumference is greater than its inner circumference includes additional integrated protuberances, or space fillers, that are added to the interior lining of the sleeping bag to fill-in around the sleeper&#39;s body. Making the circumference of the outside of the bag greater than the inside maintains the thickness of the insulation in selected areas. To maintain insulation thickness at other locations around the sleeper&#39;s body, the insulation-containing space fillers are incorporated into the interior of the bag and expand under the influence of the insulation to fill-in around the sleeper for reducing the internal volume of the bag. This construction can be carried the length of the sleeping bag.

Description:
FIELD 
     The present disclosure relates generally to sleeping bags and, more particularly, to sleeping bags that combine an insulation-containing differential construction with insulation-containing internal space filler elements adapted to expand under the influence of the insulation for reducing the internal volume of the sleeping bag during use. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     A sleeping bag typically includes first and second opposed halves defining a sleeping compartment therebetween and which are connected in such a way to define an entrance aperture at an entrance side or end of the sleeping bag. Each half of the sleeping bag includes an outer shell and an inner shell with an insulating material disposed and retained between these two layers. Insulation thickness depends on the minimum ambient air temperatures that are expected to be encountered by the user. Colder temperatures require a greater thickness of insulation to keep heat loss from the user sufficiently low enough that the user does not become uncomfortable. 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, of a selected length to provide access to the entrance aperture and which can be located on the sides, ends or top to permit use of the sleeping bag. 
     Very lightweight, compressible insulation materials, such as water fowl down, are extremely desirable since they are able to provide sufficient insulation while being light weight and easily compressed. When used as an insulation material in sleeping bags, the down is easily compressed from the outside by the weight of the bag materials and from the inside by the user pushing outward. To assist in maintaining the insulation thickness and resist such compression, the sleeping bag can be constructed so that its outside circumference is greater than its inside circumference. This is a well-known sleeping bag construction and is normally referred to as “differential construction” or “differential cut”. Commonly, the outer shell is connected to the inner shell by baffles that create compartments or tubes into which the insulating material is placed. A sleeping bag constructed in this fashion creates an arc of insulation over the user&#39;s body. However, the arc structure that is created by the differential construction has an undesirable feature. That is, the interior surface of the sleeping bag is held away from the user&#39;s body since the sleeping bag assumes the shape of the arc. 
     SUMMARY 
     It is an aspect of the present teachings to provide a sleeping bag that overcomes the undesirable features of prior art sleeping bags. 
     In accordance with this and other aspects, the present disclosure is directed to a differential construction type of sleeping bag which incorporates insulation containing compartments, or internal space fillers, that are strategically located laterally or above the user&#39;s body and can extend either partially or completely the full length of the sleeping bag within the sleeping compartment. These insulated space fillers 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 that may have been created as a result of the differential construction. 
     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 side-zippered sleeping bag constructed in accordance with the present teachings; 
         FIG. 2A through 2D  show cross-sections of various side zippered sleeping bags incorporating the teachings of the present disclosure; 
         FIGS. 3A through 3D  illustrate a series of different internal baffle configurations applicable for use with the sleeping bags constructed according to the present disclosure; 
         FIGS. 4A through 4D  illustrate a series of different tube blocking baffle configurations applicable for use with the sleeping bags constructed according to the present disclosure; 
         FIGS. 5A and 5B  show a sleeper in back and side positions within a side-zippered sleeping bag incorporating the teachings of the present disclosure; 
         FIG. 6  shows a top-zippered sleeping bag constructed in accordance with the present teachings; 
         FIG. 7  shows a cross-section of the top-zippered sleeping bag incorporating the teachings of the present disclosure; and 
         FIGS. 8A and 8B  show a sleeper in back and side positions in a top-zippered sleeping bag incorporating the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following exemplary embodiments are 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 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 may be embodied in many different forms, and that neither should be construed to limit the scope of the present disclosure. 
     Referring to  FIG. 1 , a perspective view of an exemplary sleeping bag  10  constructed in accordance with the present teachings is shown in a partially open position, and may be constructed to have an entrance end, denoted generally by reference numeral  11 . The 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. The sleeping bag  10  is generally shown to include an outer shell  12 , an inner shell  14 , and a closure device such as a zipper assembly  16 . As is conventional, light-weight fabrics, such as nylon and polyester, are used for the exterior surfaces defined by outer shell  12  and the interior surfaces defined by inner shell  14 . The sleeping bag  10  has a first half  15  and a second half  17  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  is closed. 
     As will be detailed hereinafter with reference to  FIG. 3 , a plurality of internal baffle structures, generally identified by reference numeral  18  and which also made from lightweight man-made materials, are used to locate and maintain an insulating material  36  disposed between outer shell  12  and inner shell  14  in desired positions longitudinally and circumferentially along the length of sleeping bag  10 . Baffles  18  are attached to the outer shell  12  and the inner shell  14  by suitable means such as, for example, sewing or adhesives. A drawstring  20  can be used in conjunction with a pair of draw hems  22  and  24  to adjustably vary an opening at the top of sleeping bag  10  once zipper assembly  16  has been drawn to its closed position. A drawstring lock  26  is also provided to maintain the drawstring  20  in a preferred cinched position. 
     In accordance with one aspect of the present disclosure, sleeping bag  10  is constructed to include one or more insulation containing structures or compartments, in addition to the structures created between the differentially cut inner shell  14  and the outer shell  12 , hereinafter referred to as internal space fillers  30 , that are integrated into interior sleeping compartment  19  of sleeping bag  10  on at least one lateral side thereof. Referring to  FIGS. 2A through 2D , preferred alternative constructions for internal space fillers  30  will now be described based on a series of exemplary cross-sections through sleeping bag  10  generally taken through a typical chest and/or abdominal area of sleeping compartment  19 . Mid-side locations for zipper assembly  16  are shown in  FIGS. 2A and 2C  while low-side locations for zipper assembly  16  are shown in  FIGS. 2B and 2D . Regardless of the closure location, all of the sectional views provided by  FIG. 2  illustrate that the circumference of an inner surface  32  of inner shell  14  is less than that of an outer surface  34  of outer shell  12  for the full length of sleeping bag  10 . This particular configuration is commonly referred to as the “differential” design or cut concept. 
     As noted, insulation material  36  is retained between outer shell  12  and inner shell  14 . Space fillers  30  are defined or delineated by a spacer shell  38  and a portion of inner surface  32  of inner shell  14 , and each space filler  30  includes an insulation material  40  disposed within the enclosed compartment or compartments therebetween. Spacer shell  38  is preferably made of a material common to either outer shell  12  and/or inner shell  14  and which is suitably attached to inner surface  32  along its edges to define an enclosed compartment. The most efficient design would be to carry internal space fillers  30  along the entire length of sleeping bag  10 . However, it is contemplated that alternative arrangements of one or more space fillers  30  along one or both side wall portions of sleeping bag  10  may be utilized. 
     Insulation  36  in the first half or top portion  15  of sleeping bag  10  (disposed within transverse insulation compartments  48  between adjacent baffles  18 ) is kept separate from the insulation  36  in the second half or bottom portion  17  of sleeping bag  10  by an integrated predefined side hinge or edge  42  and zipper assembly  16  (see  FIGS. 2A and 2B ). As an alternative, insulation  36  retained in particular locations within insulation compartments/tubes  48  formed between the outer and inner shells (whether running transversely or longitudinally) and the baffles  18  can also be accomplished using internal tube-blocking baffles  44 , similar to those shown in  FIGS. 2C and 2D . Regardless, sleeping bags  10  shown in  FIGS. 2A through 2D  each include a pair of laterally-spaced internal space fillers  30  that are filled with insulation  40 . It will be appreciated that baffles (not shown) similar to baffles  18  can be integrated into each of internal space fillers  30  either transversely or longitudinally or some combination thereof to maintain insulation  40  in desired locations. 
       FIGS. 3A through 3D  show a series of different insulation retention chamber/tubes  48  that may be used with sleeping bag  10 . These tubes  48  may run transversely or longitudinally, or any combination thereof relative to the length of sleeping bag  10 . Tubes  48  are created between an outer shell material  50 , an inner lining material  52  and baffles  18  made from a baffle material  54 . Insulation material  36  is inserted into compartments  48  thus formed. 
       FIGS. 4A through 4C  show a series of different types of tube blocking baffles, or in the case of  FIG. 4D , no baffle that may be used to control/limit shifting of insulation  36  in insulation retaining space fillers  30  of  FIG. 2  and/or insulation retaining chambers/tubes  48  of  FIG. 3 . These baffles  60  are illustrated to extend between outer shell  12  and inner shell  14  and are perpendicular to the longitudinal direction of the insulation retaining chambers/tubes  48  described in reference to  FIG. 3 . 
       FIGS. 5A and 5B  show a sleeper  63  in a side-zippered sleeping bag  10  incorporating various aspects of the present invention. The sleeper  63  and sleeping bag  10  are positioned on a semi-non-compressible pad/mattress  61 . Differentially cut lower sleeping bag element  62  and upper sleeping bag element  64 , together with space filler elements  30 , comprise the invention.  FIG. 5  shows that the insulation thickness is maintained and internal spaces/volumes are minimized by integration of space filler elements  30  into sleeping bag  10 . This is demonstrated by sleeper  63  on his/her back in  FIG. 5A  and on his/her side in  FIG. 5B . 
       FIG. 6  shows a sleeping bag  100  that incorporates a top closure device, such as a zipper assembly  116 . Light-weight fabrics using man made materials, e.g., nylon and polyester, are again used for the exterior surfaces of an exterior shell  112  and the interior surfaces of an inner shell  114 . An internal baffle structure  118 , also made of lightweight man-made materials, is again used to locate and maintain an insulation material  136  in the desired positions. Details regarding various baffle designs  118  have been previously shown in  FIG. 3 . As before, baffles  118  are attached by sewing, gluing or other means of attachment to the inner and outer shells. A drawstring  120  is used in conjunction with draw hem  122  to vary an opening  121  at the top of sleeping bag  100  once zipper assembly  116  has been drawn to its closed position. This figure clearly shows an insulation containing structure, or an internal space filler  130 , that has been added to the interior sleeping compartment of sleeping bag  100  at the top portion thereof. 
       FIG. 7  shows the cross-section of the chest and abdominal area of the top-zippered sleeping bag  100  shown in  FIG. 6 . The sectional view of  FIG. 7  shows that the circumference of inner shell  114  is less than that of outer shell  112 , whereby the inner circumference is less than the outer circumference for the full length of sleeping bag  100 . This again defines the differential design or differential cut configuration. Insulation  136  is retained between outer shell  112  and inner liner  114 . Internal space filler element  130  is defined by a spacer shell material  138  and interior surface  132  and further includes an insulation material  140  that is contained between those surfaces. The most efficient design would be to carry space filler element  130  the full length of sleeping bag  100 , however, some designs may choose selected locations along the length of the bag. Retaining insulation  136  in a particular location in any insulation tube formed by the outer and inner shells and the interior baffling system (whether running transversely or longitudinally to the long direction of the bag) is also accomplished by using an internal tube-blocking baffle, see  FIG. 4 . Additional attachment features (i.e., loop and pile, secondary zippers), may be used to aid closure. 
       FIG. 8  shows a sleeper  63  in a top-zippered sleeping bag  100  incorporating the teachings of the present invention. The sleeper  63  and sleeping bag  100  are positioned on a semi-non-compressible pad/mattress  61 . Differentially cut sleeping bag side elements  153  together with space filler element  130  comprise the invention.  FIG. 8  shows that insulation thickness is maintained and the internal spaces/volumes are minimized by the present invention. This is demonstrated by sleeper  63  on his/her back in  FIG. 8A  and on his/her side in  FIG. 8B . 
     It will be appreciated that the particular construction and closure systems disclosed in association with sleeping bags  10 ,  100  are merely intended to be exemplary. For example, multiple zippers can be used to permit access to the internal sleeping chamber. Likewise, other closure systems such as, for example, loop and pile (VELCRO®) can be used. Furthermore, the internal space filler elements  30 ,  130  can be releaseably attached via loop and pile attachment systems within the internal sleeping chamber. Accordingly, removeable space filler elements  30 ,  130  may be “retro-fit” into existing conventional sleeping bags. 
     While specific aspects have been described in the specification and illustrated in the drawings, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements and components thereof without departing from the scope of the present teachings, as defined in the claims. Furthermore, the mixing and matching of features, elements, components and/or functions between various aspects of the present teachings are expressly contemplated herein so that one skilled in the art will appreciate from the present teachings that features, elements, components and/or functions of one aspect of the present teachings can be incorporated into another aspect, as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation, configuration, or material to the present teachings without departing from the essential scope thereof. Therefore, it is intended that the present teachings not be limited to the particular aspects illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out the present teachings, but that the scope of the present teachings include many aspects and examples following within the foregoing description and the appended claims.