Inflatable Insulating Material

Abstract

Disclosed herein is a thermal insulating material formed of sheets of non-porous flexible material hermetically sealed together to define an inflatable volume divided into a two-dimensional array of compartments joined by gas communication passages. The boundaries between the compartments of the array define a plurality of intersecting lines along which the array can be easily flexed and a valve is provided for inflation of the compartmented volume.

Description

BACKGROUND OF THE INVENTION This invention relates generally to thermal insulating materials and, more particularly, to highly flexible and comformable materials having insulation properties that can be easily varied to compensate for changes in ambient conditions.

Most insulating materials depend on the low thermal conductivity of air to provide their low overall conductance of heat. This is true of protective clothing and of building or industrial insulating materials which contain air spaces in their structure. In most of these, the air spaces are small enough to minimize heat transfer by convection since, under ordinary conditions, convection will begin to affect the conductance through still air when the gap exceeds five-eighths inch. But because the overall conductance of these materials depends on the heat conducted through the material as well as through the still air, it is generally desirable to minimize the former by using low conductivity materials when possible, by using as little material as possible while maintaining structural integrity; and by minimizing the number or lengthening the paths through which the heat can travel. Finally, since heat is also transferred by radiation across the air spaces, opacification, reflective surfacing, or radiation barriers can also be incorporated into the insulating materials.

However, in these materials the overall conductance cannot be changed at will. This is a property that can be particularly useful, for example, in protective clothing, such as jackets or vests, or in blankets and sleeping bags wherein a single article may serve comfortably over a range of ambient temperature. Inflatable structures that have been proposed previously to provide variable insulation consist of tubular compartments similar in pattern to those used in air mattresses. These structures have two principal limitations. First, as their thickness is increased by inflation, their lateral dimension shrinks as much as 30 percent, thus making it difficult to have the garmet fit when inflated as well as when deflated. Secondly, the inflated material in these structures becomes relatively rigid and does not flex easily or conform in shape to different surfaces.

The object of this invention, therefore, is to provide a highly flexible, light weight, easily conformable insulation material, the conductance of which can be changed at will by inflation, in so doing significantly altering only its thickness dimension, and which can be carried and stored with little bulk in its deflated state.

SUMMARY OF THE INVENTION

The present invention is characterized by the provision of thermal insulating material formed of sheets of non-porous flexible material hermetically sealed together to define an inflatable volume divided into a two-dimensional array of compartments joined by gas communication passages. The boundaries between the compartments of the array define a plurality of intersecting lines along which the array can be easily flexed and a valve is provided for inflation of the compartmented volume. When increased thermal insulation is desired, the compartmented volume is inflated thereby substantially decreasing the conductivity of the material which nevertheless remains highly flexible and conformable because of the flex lines defined by the two-dimensional array.

In a featured embodiment of the invention, the individual compartments are formed by bonds between the sheets of polymeric material at the intersections of lines defining the two-dimensional array. Utilization of materials that can be bonded together by any of many well-known techniques to form the compartment array greatly simplifies the construction of thermal insulation according to the invention.

According to another feature of the invention, at least one of the flexible material sheets possesses hexagonally arranged preformed blisters that define the compartments of the inflatable volume. Because of the preformed blisters, inflation of the compartments formed thereby introduces no distortion in the overall shape of the material thereby facilitating its use for items such as wearing apparel wherein a constant uniform overall size is desired. The hexagonal arrangement of compartments enhances comfortableness by allowing uniform flexing of the material in any direction.

In another featured embodiment, the insulation material of the present invention is attached as a lining to an article of wearing apparel. The lining flexes easily so as to readily conform to the anatomy of the wearer even during movement. Preferably the individual compartments of the array are relatively small with a maximum cross section of less than one square inch so as to provide the flexibility desired for an article of clothing. Also the individual compartments preferably have a maximum inflated thickness of less than one inch to further enhance flexibility.

For applications requiring additional thermal insulation capability, another embodiment of the invention provides a third sheet of flexible sheet material hermetically sealed over the inflatable volume formed by the other sheets and providing an auxiliary volume that can be inflated or deflated independently with a separate valve mechanism. When the degree of insulation provided by inflation of the primary volume is inadequate, the auxiliary volume also can be inflated to further improve the insulation properties of the material.

DESCRIPTION OF THE DRAWINGS

These and other objects and features of the invention will become more apparent upon a perusal of the following description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic illustration of an article of wearing apparel according to the present invention;

FIG. 2 is a cross-sectional view taken along lines 2-2 in FIG. 1;

FIG. 3 is a more detailed plan view of a portion of the thermal insulation material shown in FIGS. 1 and 2;

FIG. 4 is a cross sectional view taken along lines 4--4

FIG. 5 is a cross sectional view taken along lines 5--5 of FIG. 3 with the insulation material inflated;

FIG. 6 is a partial perspective view of other compartmented array for use in the insulation material of the present invention; and

FIG. 7 is a partial cross sectional view illustrating another insulating material embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1 and 2 there is shown a coat 11 having, in the conventional manner, an outer covering 12 and a lining 13. The materials composing the outer covering 12 and the lining 13 are selected to provide desirable characteristics of appearance, wear resistance, comfort, etc. Also, the outer covering 12 can be opacified or coated reflectively to reduce heat conductance through radiation. Sandwiched between the outer layer 12 and the lining 13 is an inflatable intermediate lining 14 described in detail below. A conventional valve assembly 15 is associated with the intermediate lining 14 and permits inflation and deflation thereof. The valve assembly 15 is retained within a pocket 16 positioned so as to render the valve accessible to the mouth of a person wearing the coat 11. This permits a wearer to inflate the lining 14 by blowing into the valve 15.

FIGS. 3-5 show more detailed views of a portion of the thermal insulation material 14 illustrated in FIGS. 1 and 2. The material 14 is formed by a first sheet 21 of non-porous, flexible material sealed along outer edges 22 to a second sheet 23 of non-porous, flexible material so as to form a hermetically sealed inflatable volume 24. Preferably, the sheet materials 21 and 23 are formed of a suitable polymeric material or coated fabric that possesses good strength and tear characteristics and remains non-rigid at sub-zero temperatures. Performed in the first sheet 21 is an array of blisters 25 separated by troughs 26 that divide the volume 24 into compartments 27. The blisters 25 can be preformed by any suitable technique such as heat forming, molding, etc. At hexagonally distributed positions 28 the troughs 26 are bonded to adjacent portions of the second sheet 23 so as to limit the degree of separation possible between the sheets 21 and 23. Both the sealed edges 22 and the bonds 28 can be created by a variety of well known methods including thermal heat sealing, impulse sealing, dielectric sealing, and ultrasonic welding as well as by the use of coatings and adhesives.

The preformed blisters 25 permit inflation of the compartments 27 without any stretching of the sheets 21 and 23 while the bonds 28 retain a minimum separation therebetween. Accordingly, the length d of the non-inflated material section shown in FIG. 4 is the same as the lenght D of the same section shown in FIG. 5 after inflation. This is an important feature of the invention in that it insures that the peripheral dimensions of the material 14 will remain uniform. Because of this feature, the insulation liner will conform dimensionally with the outer covering 12 and provide a good fit in either the inflated or non-inflated conditions. In this arrangement it is evident that the flat surface 23 of FIGS. 3-5 can be the same as the inner lining 13 of FIG. 2.

Another important feature of the invention is the division of the inflatable volume 27 into a two-dimensional array of compartments 27. The troughs 26 define a plurality of intersecting lines along which the array 14 can be easily flexed. Thus, the two-dimensional array provided the material 14 with flexibility in all directions adding substantially to the degree of comfort it provides to a wearer when used as an article of clothing. Although other array patterns can be employed, the hexagonal pattern is preferred in that it provides the most uniform flexing ability in all directions. The ability of the material to flex can be enhanced by reducing the size and increasing the density of the compartments within the array. For the degree of flexibility desired for clothing, it is preferably that the maximum cross-sectional area of the individual compartments as illustrated in FIG. 3 be no greater than one square inch.

The thickness of the material 14 is determined by the geometry or inflated height of the blisters 25 for a fixed pattern density. Thus, the pattern density or blister height can be varied as needed in a given application to enhance or diminish flexibility, ventiliation, insulation, or bulkiness in local areas. Again however, for the use of the material in a clothing application it is preferred that the height of the blisters be limited to less than 1 inch. Though the insulating property tends to increase with greater blister height, for blister heights greater than one inch the insulation effectiveness of the air filled compartments is reduced by convection effects, overall flexibility is reduced and bulkiness is increased. For applications where additional warmth is required, and so that the insulation can be varied in increments, it is preferable to use two layers of material or to use a material provided with a multiple inflatable compartments as illustrated in FIG. 8 and described in greater detail below.

FIG. 6 shows in perspective another insulation material embodiment of the invention. The material 31 is formed by a first flat sheet 32 and a second flat sheet 33, both formed of a suitable non-porous flexible material. The sheets 32 and 33 are hermetically sealed along their edges 34 to form an inflatable internal volume therebetween. Bonds are also created between the first and second sheets 32 and 33 at a plurality of points 35 distributed in a hexagonal array. Because of the bonds 35, the material 31 assumes the quilted appearance shown in FIG. 7 after inflation and provides the same selective degree of thermal insulation provided by the embodiment shown in FIGS. 3-6. Although not quite as uniformly flexible or resistant to changes in peripheral dimensions as embodiment 14, the absence of preformed blisters simplifies construction of the material 31.

Another insulation material embodiment 41 is schematically illustrated in FIG. 7. The material 41 includes first and second sheets 42 and 43, respectively, of non-porous flexible materials arranged identically to the sheets 21 and 23 shown in FIGS. 3-5. However, in embodiment 41 a third sheet 44 of non-porous flexible material is hermetically sealed to the sheet 43 providing an auxiliary volume 45 overlaying and coextensive with a volume 46 defined by the first sheet 42. Each of the sheets 42 and 44 includes preformed blisters 47 separated by troughs 48 that define compartments as in the embodiment 14 shown in FIG. 3. Bonds 49 are made between the flat second sheet 43 and directly adjacent through portions of both the first and third sheets 42 and 44. During use of embodiment 41, the volume 46 can be inflated through a suitable valve 51 when increased insulation is desired and an even greater degree of insulation can be obtained by subsequently inflating the volume 45 through an auxiliary valve 52.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, although wearing apparel is a preferred application for the present thermal insulation material, it will be obvious that the material can be used also for other articles such as sleeping bags, tents, blankets, etc. Also, in certain applications, the provision within the material of isolated regions that would permit zonal inflation would provide greater versatility, particularly when used as an article of wearing apparel. In addition, the ability of the material to breathe can be easily established by providing small openings through all sheets within the confines of the bonds 28, 35 or 49. It is to be understood, therefore, that the invention can be practiced otherwise than as specifically described.

Claims

What is claimed is:

1. Thermal insulation comprising:

a first sheet of non-porous flexible material;

a second sheet of non-porous flexible material hermetically sealed to said first sheet around a peripheral edge so as to define therebetween and inflatable volume, opposite portions of said peripheral edge being joined by portions of said first sheet having a length in the direction of separation of said opposite portions substantially greater than the maximum normal separation possible between said opposite portions in that direction;

divider means dividing said inflatable volume into a two-dimensional array of compartments joined by gas communication passages; and

valve means for introducing gas into said inflatable volume.

2. Thermal insulation according to claim 1 wherein said divider means comprise direct bonds formed between said first and second sheets of flexible material.

3. Thermal insulation according to claim 1 wherein the boundaries between said compartments of said two-dimensional array define a plurality of intersecting lines along which said array can be easily flexed.

4. Thermal insulation according to claim 3 wherein the divider means comprise bonds formed between said first and second sheets of flexible material at said intersections of said lines.

5. Thermal insulation according to claim 1 wherein discrete area of said first sheet of flexible sheet material are preformed blisters that define said compartments.

6. Thermal insulation according to claim 5 wherein the boundaries between said compartments of said two-dimensional array define a plurality of intersecting lines along which said array can be easily flexed.

7. Thermal insulation according to claim 6 wherein said divider means comprise bonds formed between said first and second sheets of flexible material at the intersections of said lines.

8. Thermal insulation according to claim 5 including a third sheet of non-porous flexible sheet material providing a hermetically sealed auxiliary volume overlaying and coextensive with said inflatable volume, and auxiliary valve means for introducing gas into said auxiliary volume.

9. Thermal insulation according to claim 8 wherein discrete areas of said third sheet of flexibe material are preformed blisters aligned with said blisters in said first sheet of flexible sheet material.

10. Thermal insulation according to claim 1 wherein said inflatable volume has a configuration corresponding to a portion of the human anatomy.

11. Thermal insulation according to claim 10 including an article of wearing apparel to which said first and second flexible sheets are attached as a lining.

12. Thermal insulation according to claim 11 wherein the boundaries between said compartments of said two-dimensional array define a plurality of intersecting lines along which said array can be easily flexed.

13. Thermal insulation according to claim 12 wherein said divider means comprise bonds formed between said first and second sheets of flexible material at the intersections of said lines.

14. Thermal insulation according to claim 11 wherein discrete areas of said first sheet of flexible sheet material are preformed blisters that define said compartments.

15. Thermal insulation according to claim 14 wherein the boundaries between said compartments of said two-dimensional array define a plurality of intersecting lines along which said array can be easily flexed.

16. Thermal insulation according to claim 11 wherein said compartments have a maximum inflated thickness of less than one inch.

17. Thermal insulation according to claim 16 wherein said compartments have a maximum cross-section of less than one square inch.

18. Thermal insulation according to claim 1 wherein said two-dimensional array is a hexagonal array.

19. Thermal insulation comprising:

a first sheet of non-porous flexible material;

a second sheet of non-porous flexible material hermetically sealed to said first sheet around a peripheral edge so as to define therebetween an inflatable volume;

bonding means directly bonding said first sheet and said second sheet together at spaced points within said peripheral edge so as to divide said inflatable volume into a two-dimensional array of compartments joined by gas communication passages between said compartments and wherein said first and second sheets are of such area as to permit substantial increase in the volume of said compartments in response to inflation thereof without distortion of said peripheral edge; and

valve means for introducing gas into said inflatable volume.

20. Thermal insulation according to claim 19 wherein the boundaries between said compartments of said two-dimensional array define a plurality of intersecting lines along which said array can be easily flexed.

21. Thermal insulation according to claim 19 wherein discrete areas of said first sheet of flexible sheet material are preformed blisters that define said compartments.

22. Thermal insulation according to claim 19 wherein said two-dimensional array is a hexagonal array.