LIGHTWEIGHT, COMPACT AIR MATTRESS
United States Patent 3813716
A lightweight, compact air mattress particularly suitable for use for backpacking is disclosed. The air mattress is comprised of a lightweight, thin walled casing having a plurality of side-by-side elongated pockets and a plurality of small diameter, individual, inflatable tubular members removably mounted in the pockets. Each inflatable tube has its own valve means for inflation thereof, and the tubular members are also formed of a thin, lightweight material such as polyvinyl chloride. The low volume tubes are inflated until fully distended to provide proper cushioning. The casing material is preferably a woven nylon and both the casing and tubes are abrasion and puncture resistant, but not puncture proof. Puncturing of the tubular members is tolerated, since they may be readily removed for repair or replacement.
US Patent References:
/1285391.html
Robertson - November 1918 - 1285391
Mattress
Tufenkjian - October 1929 - 1733034
INFLATABLE FURNITURE
Williams - June 1971 - 3584914
/3635528.html
Strom - January 1972 - 3635528
/1285391.html
Robertson - November 1918 - 1285391
Mattress
Tufenkjian - October 1929 - 1733034
INFLATABLE FURNITURE
Williams - June 1971 - 3584914
/3635528.html
Strom - January 1972 - 3635528
Application Number:
05/276425
Publication Date:
06/04/1974
Filing Date:
07/31/1972
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
297/DIG.003
International Classes:
A47C27/08; A47C27/08
Field of Search:
5/343,344,348-350,355 297/DIG.3
Primary Examiner:
Nunberg, Casmir A.
Attorney, Agent or Firm:
Warren, Rubin, Brucker & Chickering
Claims:
I claim
1. In a lightweight, compact air mattress for use for backpacking having a casing having opposed sheet portions formed to define a plurality of side-by-side elongated pockets having access openings thereto, said openings and pockets being dimensioned for receipt of a plurality of inflatable tubular members, and a plurality of individual elongated inflatable tubular members each being removably mounted in said pockets through said openings in said casing, the improvement comprising:
2. A lightweight, compact air mattress as defined in claim 1 wherein,
3. A lightweight, compact air mattress as defined in claim 2 wherein,
1. In a lightweight, compact air mattress for use for backpacking having a casing having opposed sheet portions formed to define a plurality of side-by-side elongated pockets having access openings thereto, said openings and pockets being dimensioned for receipt of a plurality of inflatable tubular members, and a plurality of individual elongated inflatable tubular members each being removably mounted in said pockets through said openings in said casing, the improvement comprising:
2. A lightweight, compact air mattress as defined in claim 1 wherein,
3. A lightweight, compact air mattress as defined in claim 2 wherein,
Description:
BACKGROUND OF THE INVENTION
In recent years there has been a considerable increase in the interest in outdoor camping of all kinds and, more particularly, there has been a substantial increase in the interest in backpacking. As the name implies, backpacking depends upon the ability of an individual to carry in a pack on his back all of the items which he will need on a camping trip. A backpack will typically weigh between 40 and 60 pounds, depending upon the size of the individual and the length and nature of the camping trip. Although the weight of the backpack may vary, there is almost always an extreme premium placed upon the use of lightweight and low volume equipment. As a result, numerous lightweight products have been developed for use by the backpacker, including tents, cooking equipment, food, sleeping bags, and the like.
In connection with sleeping equipment, lightweight, low volume, down-filled sleeping bags are commonly employed since they are compact and lightweight while affording substantial warmth for the outdoor camper. Down-filled sleeping bags, however, provide little cushioning between the ground and the camper, and accordingly, they lack a certain degree of comfort which would be desirable. Some backpackers have learned to overcome this discomfort by attempting to select desirable camping sites and simply learning to tolerate the lack of cushioning which the sleeping bags afford. Alternatively, foam rubber pads or cushions have been employed to enhance the sleeping comfort of the backpacker. These foam rubber pads have the advantage of being relatively lightweight, but they have the disadvantage of being relatively bulky. The size and mobility of the pack and therefore the agility of the backpacker is decreased or some other piece of equipment must be left behind when foam rubber cushions are placed in the pack. It should be noted further that the foam rubber cushion often is only a marginal improvement over sleeping on the ground, since the foam rubber cannot be thick enough to give total comfort without increasing the volume of the cushion to a completely unmanageable size.
Another approach which has been attempted by the backpacker is to employ an inflatable air mattress. Such air mattresses are well known and typically formed of a synthetic or natural rubber which is reinforced with a fiber, which also can be synthetic or natural. The air mattress is placed under the camper's sleeping bag and greatly increases the backpacker's comfort during sleeping. Such air mattresses, however, are prohibitively heavy for many backpacking outings and are further usually more bulky than is desired. Typical of a combination air mattress and sleeping bag for use by campers is shown in U.S. Pat. No. 1,648,373. This type of air mattress and sleeping bag combination would undoubtedly afford the camper considerable comfort and may well be entirely adequate for use in car-camping. While a mattress constructed in accordance with the disclosure of this patent might be collapsible to a very small volume and be relatively lightweight by comparison to the volume and weight that can be carried in the trunk of a car, this structure is totally unsuitable and unacceptable for use by a backpacker because of its extreme bulk and weight.
Undoubtedly one of the primary problems involved in using an inflatable or pneumatic mattress for backpacking is that the camper will necessarily subject the mattress to an environment which is inherently unfavorable to inflatable equipment. Thus, the mattress will be exposed to puncturing from rocks, sticks, and the like. Thus, present camping mattresses are formed of heavy rubber which is further reinforced with fiber to prevent punctures and abrasions which will cause failure of the mattress. It is this approach to the construction of air mattresses which results in their increase in bulk and weight beyond that which is tolerable by the backpacker.
In addition to the relatively simple rubber air mattress which is used in car-camping, more complicated pneumatic or inflatable mattresses have been evolved, primarily for use in the home. For example, U.S. Pat. Nos. 2,039,289 and 2,328,083 both disclose inflatable air mattresses designed for home use. Mattresses constructed in accordance with the disclosures of these two patents would again be unacceptably heavy, bulky and complicated if attempted to be employed by the backpacker.
Accordingly, it is an object of the present invention to provide an air mattress and method which is suitable for use for backpacking and which is very light in weight and compact in size.
It is another object of the present invention to provide an air mattress and method, suitable for use for backpacking, which can be easily and rapidly inflated and deflated.
Another object of the present invention is to provide an air mattress which is suitable for use for backpacking and which does not fail to provide necessary support upon puncturing of an element.
Still a further object of the present invention is to provide an air mattress suitable for use in backpacking in which repair or reconstruction of the mattress can be easily accomplished.
The air mattress and method of the present invention have other objects and features of advantage which will become apparent upon consideration of the following detailed description of the preferred embodiment and the accompanying drawings.
SUMMARY OF THE INVENTION
The inflatable air mattress of the present invention is comprised, briefly, of a very lightweight casing having a plurality of side-by-side pockets formed therein and dimensioned for receipt of a plurality of inflatable elements. In addition, a plurality of relatively small diameter inflatable members are removably mounted in the casing and formed from a thin-walled, lightweight material. The inflatable elements are inflated until fully distended in order that the small diameter will give sufficient cushioning. The use of a plurality of small diameter elements, each of which is independent, inside a protective casing affords a mattress construction in which periodic puncturing of an element is contemplated and can be tolerated, enabling the use of lightweight, compact material. The elements are readily removable from the casing for repair or replacement, and tab means are provided for insertion of the elements into the casing. The valve in each inflatable element is formed to allow a positive pressure to be applied to the air inside the element while the valve is being closed to insure full distention and inflation of the elements.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of an air mattress for use for backpacking constructed in accordance with the present invention.
FIG. 2 is a top plan view of an inflatable member employed in the mattress of FIG. 1.
FIG. 3 is an enlarged, cross-sectional view taken along the plane of line 3--3 in FIG. 1.
FIG. 4 is an enlarged, cross-sectional view taken along the plane of line 4--4 in FIG. 2.
FIG. 5 is an enlarged, cross-sectional, fragmentary view taken along the plane of line 5--5 of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIGS. 1, 2 and 3, the lightweight, compact air mattress of the present invention can be seen to be comprised of a casing, generally designated 21, having opposed sheet portions 22 and 23 formed to define a plurality of side-by-side elongated pockets 24. Pockets 24 are preferably formed by stitching the upper and lower sheet portions 22 and 23 together along longitudinally extending lines 26, and the pockets are dimensioned for receipt of a plurality of inflatable tubular members.
In order to insure that the air mattress of the present invention is suitable for use for backpacking, casing 21 is formed of a very thin, high strength, lightweight material, such as woven nylon fabric. In the air mattress of the present invention, casing 21 does not function to prevent all punctures of the inflatable tubular members. Instead, the primary purpose of the casing is to hold the inflatable members in a mattress array and provide some limited protection against puncturing. Thus, "very thin" as used herein does not mean a sheet thick enough to prevent puncturing. Instead, the expression "very thin" as used herein shall mean a material having a thickness of no greater than about 0.006 inches. Furthermore, the term "lightweight" as used in connection with the casing material throughout shall mean a material having a weight in the range of about 1.2 to about 1.9 ounces per square yard. In this regard, it has been found highly advantageous to employ a woven nylon having a thickness of 0.003 inches as the casing material since it provides a certain degree of abrasion and puncture resistance, has sufficient strength to hold the inflatable tubular members in the desired mattress array, and has a weight in the desired range.
Removably mounted in pockets 24 of casing 21 are a plurality of elongated, inflatable tubular members 31. In order that the weight and bulk of the mattress of the present invention be reduced and further in order that adjacent elements can be in a position to give support, the inflatable tubular members each have a relatively small diameter cross-section and each tubular member is provided with its own valve means 32 for inflation thereof. Again, the tubular members are formed of thin, lightweight material and are mounted in openings in the casing 21 with valve means 32 accessible to the openings for inflation of the tubular members while in the casing. As shown in FIG. 1, casing 21 is provided with a zipper closure 27, allowing the end 28 of the casing to be selectively opened and closed to expose valves 32 for inflation and deflation.
Again, it is not the purpose of the present invention to form the inflatable tubular members of a material having sufficient strength or wall thickness to prevent puncturing. This approach, as above outlined, results in a mattress which is too heavy and/or bulky. Therefore, as used herein in connection with the inflatable tubular members the term "thin" shall mean a member having a wall thickness between about 0.005 inches and about 0.012 inches. Additionally, the expression "relatively small diameter" as used in connection with the inflatable tubular members of the present invention shall means members having an inflated cross-sectional diameter less than about 2.5 inches. The independently inflatable and deflatable nature of the plurality of tubular members, the small diameter cross-section, and the thin, lightweight material from which the tubular members are made, all combine to enable the formation of a lightweight, compact air mattress suitable for backpacking by functioning on the basic principle that puncturing of the inflatable elements will occur and can be tolerated. While other inflatable mattress constructions have recognized that puncturing can occur, they have gone to great lengths to prevent and minimize the possibility of puncturing. Thus, a plurality of layers of material or combinations of material and rubber have been employed to prevent puncturing. In the present invention, casing 21 is very lightweight, as are tubular members 31. Accordingly, the backpacker must expect that puncturing of a tubular element will periodically occur. When puncturing does happen, however, only a single element will normally be affected at any one time, and the small diameter of the tubular elements will cause the weight of the camper to be supported on closely adjacent members. A camper may, therefore, experience a puncture of an element in the middle of the night and still be comfortably supported on the adjacent elements throughout his night's sleep. In the morning, the camper will merely remove the punctured element and replace the same with a spare tubular element or merely patch or repair the damaged element with a simple repair kit. The reduction in diameter of the inflatable tubular members additionally has an attendant savings in bulk and weight. It has been found highly advantageous to form tubular elements 31 from polyvinyl chloride having a wall thickness of 0.008 inches. Polyvinyl chloride can be readily sealed along edges 33 (best seen in FIG. 4) by heat sealing equipment and valve means 32 can be readily incorporated into the polyvinyl chloride tube by heat sealing or adhesives to provide the inflatable member.
It is a further feature of the present invention to allow rapid insertion of replacement tubes or repaired tubes into casing 21 that each tubular member 31 be provided with a tab means 34 adjacent end 36 thereof. The tab is preferably formed for releasable engagement by an elongated rigid member such as by providing an opening 37 into which the end of a stick can be inserted. With the tubular member deflated, a willow stick, for example, can be inserted in opening 37 and used to push the tubular member down pocket 24 in the casing, after which the stick may be pulled from the pocket and the tubular member inflated.
Another important advantage of the air mattress of the present invention accrues by reason of the construction of the mattress with relatively small diameter tubular members, namely, the volume required to inflate and deflate the mattress of the present invention is relatively low. Much of the backpacking which occurs takes place in mountainous areas, and often at very high elevations. A standard air mattress may require five minutes or more inflation time at sea level, with this time being further substantially increased at higher elevations where the air is thinner. A backpacker does not want to spend 5 to 10 minutes inflating his air mattress if this can be avoided. Since the volume in a tubular mattress increases with the square of the diameter of the tubes, reduction of the tube diameter from the standard 5 or 6 inch diameter air mattresses to 2 inch or 2 and 1/2 inch diameter tubes results in a substantial time savings to the camper in inflating his mattress. Conversely, the plurality of independently inflatable and deflatable tubes and valves allows the air mattress of the present invention to be rapidly deflated. In standard mattresses, the entire volume of the mattress normally must pass out a single valve, and that volume is much greater than the mattress of the present invention.
In order to insure sufficient cushioning from the small diameter inflatable tubes of the present invention, the mattress should be inflated until tubes 31 are substantially completely inflated or distended. Because the volume of each individual tube is low, valve means 32 is preferably formed for operation from an opened to a closed position while a positive air pressure is maintained on the volume of air inside tubular member 31. One such valve construction is briefly illustrated in FIG. 5 and set forth in more detail in U.S. Pat. No. 2,859,932. Such a valve mechanism includes a reciprocal tubular element 41 having an opening 42 therein. The reciprocal element is mounted in a housing 43 having a frusto-conical seat portion 44 against which a mating frusto-conical surface 46 on the reciprocal element 41 can seat. In the position as shown in FIG. 5 air will pass down tubular element 41 out opening 42 and around surface 46 and out opening 47 to the interior of tube 31. To seal the valve, one may merely reciprocate element 41 until surfaces 46 and 44 mate at which point air cannot pass either into or out of the inflatable tubular member. Thus, the camper can blow the tubular member up until it is fully inflated and maintain a positive pressure on the air inside the tubular member while reciprocating the element 41 to closed position with his teeth. Other valve constructions which will allow the simultaneous maintenance of a positive pressure while sealing would include valves in which the sealing action occurs upon rotation of an element.
It is another feature of the present invention that the pockets in casing 21 defining opposite peripheral edges of the mattress and the tubular members mounted in such pockets may be of larger diameter than the tubular members intermediate of the edge defining pockets. As shown in FIG. 3, one tubular member 51 is formed of a larger diameter than the remaining tubular members. A second larger diameter tubular member would be provided at the opposite edge of the mattress to create a cradling effect tending to keep the camper's sleeping bag on the mattress. For simplicity of illustration, a large diameter tubular member is only shown on one side of the mattress with the opposite side illustrating pockets 24 with the tubular members removed therefrom. Since each of the tubular members in the mattress of the present invention are independently inflatable and deflatable, it would be possible for the camper to selectively determine whether or not to inflate element 51 to its distended diameter and create a cradling effect or only partially inflate element 51 and create a substantially level upper mattress surface.
EXAMPLE
A comparison of the mattress of the present invention with comparable foam rubber cushions and a standard rubber-fabric air mattress illustrates the advantages of the mattress construction of the present invention as employed by backpackers. The air mattress of the present invention is preferably constructed with eight or nine two-inch diameter inflatable tubes having a length of about 31/2 to 4 feet. As so constructed, the mattress will readily cushion or support the upper body of the camper. Support for the camper's legs is not usually required, and conventional air mattresses and foam rubber cushions often are constructed which are not full-length. 8 mil polyvinyl chloride tubing having heat sealed seams and a push-pull valve heat sealed therein was used to construct the mattress of the present invention. Table 1 set forth hereinbelow compares a mattress so constructed with comparably sized standard air mattresses and foam rubber cushions.
TABLE 1 ____________________________________________________________ ______________ Mattress Packing Volume (cubic inches) Weight Tube Diameter (thickness) (inches) Air Volume (cubic inches) Inflation Time (Deflation Time (minutes) ____________________________________________________________ ______________ 1. Standard rubber-fabric air mattress 300-325 4.5-5.0 lb. 5.5 5000-6000 5 or more 4 2. Foam rubber cushion 600-650 14-16 oz. 1.5 -- -- -- 3. Lightweight, small diameter tube-casing mattress 60-90 20-24 oz. 2.0 1000-1,200 2 or less 1.5 ____________________________________________________________ ______________
As will be seen from Table 1, the lightweight, small diameter mattress of the present invention occupies one-third to one-tenth of the volume which standard air mattresses or foam rubber cushions occupy in the backpack. The air mattress of the present invention weighs only about four ounces more than a foam rubber mattress, but it is 3 and 1/2 pounds or more lighter than standard rubber-fabric air mattresses. Thus, when compared to a foam rubber cushion, a 4 ounce weight increase allows a reduction in packing volume of almost 10 times. When compared to the standard air mattress, both the volume and weight are cut by a factor of at least three. It should be noted further that the weight and volume on the foam rubber cushion are probably optimistically stated since the cushion is only 1.5 inches thick while the air mattress of the present invention is 2 inches thick. This is significant since the foam rubber cushion having a thickness of only 1.5 inches does not afford the same comfort as the air mattress of the present invention.
A comparison of the volume of air in the air mattress of the present invention and the inflation and deflation times with the standard air mattress further reveals the substantial advantages of the small diameter, multiple tubed construction. In effect, the air mattress of the present invention allows the backpacker to have the comforts of the large, heavy standard air mattress, which comforts are not achievable by the relatively thin foam rubber cushion, without the attendant volume and weight disadvantages. Moreover, the use of thin, lightweight materials in which puncturing is contemplated and tolerable affords a mattress having a comparable weight to the lightweight foam cushion and a substantially reduced volume and increased comfort.
In recent years there has been a considerable increase in the interest in outdoor camping of all kinds and, more particularly, there has been a substantial increase in the interest in backpacking. As the name implies, backpacking depends upon the ability of an individual to carry in a pack on his back all of the items which he will need on a camping trip. A backpack will typically weigh between 40 and 60 pounds, depending upon the size of the individual and the length and nature of the camping trip. Although the weight of the backpack may vary, there is almost always an extreme premium placed upon the use of lightweight and low volume equipment. As a result, numerous lightweight products have been developed for use by the backpacker, including tents, cooking equipment, food, sleeping bags, and the like.
In connection with sleeping equipment, lightweight, low volume, down-filled sleeping bags are commonly employed since they are compact and lightweight while affording substantial warmth for the outdoor camper. Down-filled sleeping bags, however, provide little cushioning between the ground and the camper, and accordingly, they lack a certain degree of comfort which would be desirable. Some backpackers have learned to overcome this discomfort by attempting to select desirable camping sites and simply learning to tolerate the lack of cushioning which the sleeping bags afford. Alternatively, foam rubber pads or cushions have been employed to enhance the sleeping comfort of the backpacker. These foam rubber pads have the advantage of being relatively lightweight, but they have the disadvantage of being relatively bulky. The size and mobility of the pack and therefore the agility of the backpacker is decreased or some other piece of equipment must be left behind when foam rubber cushions are placed in the pack. It should be noted further that the foam rubber cushion often is only a marginal improvement over sleeping on the ground, since the foam rubber cannot be thick enough to give total comfort without increasing the volume of the cushion to a completely unmanageable size.
Another approach which has been attempted by the backpacker is to employ an inflatable air mattress. Such air mattresses are well known and typically formed of a synthetic or natural rubber which is reinforced with a fiber, which also can be synthetic or natural. The air mattress is placed under the camper's sleeping bag and greatly increases the backpacker's comfort during sleeping. Such air mattresses, however, are prohibitively heavy for many backpacking outings and are further usually more bulky than is desired. Typical of a combination air mattress and sleeping bag for use by campers is shown in U.S. Pat. No. 1,648,373. This type of air mattress and sleeping bag combination would undoubtedly afford the camper considerable comfort and may well be entirely adequate for use in car-camping. While a mattress constructed in accordance with the disclosure of this patent might be collapsible to a very small volume and be relatively lightweight by comparison to the volume and weight that can be carried in the trunk of a car, this structure is totally unsuitable and unacceptable for use by a backpacker because of its extreme bulk and weight.
Undoubtedly one of the primary problems involved in using an inflatable or pneumatic mattress for backpacking is that the camper will necessarily subject the mattress to an environment which is inherently unfavorable to inflatable equipment. Thus, the mattress will be exposed to puncturing from rocks, sticks, and the like. Thus, present camping mattresses are formed of heavy rubber which is further reinforced with fiber to prevent punctures and abrasions which will cause failure of the mattress. It is this approach to the construction of air mattresses which results in their increase in bulk and weight beyond that which is tolerable by the backpacker.
In addition to the relatively simple rubber air mattress which is used in car-camping, more complicated pneumatic or inflatable mattresses have been evolved, primarily for use in the home. For example, U.S. Pat. Nos. 2,039,289 and 2,328,083 both disclose inflatable air mattresses designed for home use. Mattresses constructed in accordance with the disclosures of these two patents would again be unacceptably heavy, bulky and complicated if attempted to be employed by the backpacker.
Accordingly, it is an object of the present invention to provide an air mattress and method which is suitable for use for backpacking and which is very light in weight and compact in size.
It is another object of the present invention to provide an air mattress and method, suitable for use for backpacking, which can be easily and rapidly inflated and deflated.
Another object of the present invention is to provide an air mattress which is suitable for use for backpacking and which does not fail to provide necessary support upon puncturing of an element.
Still a further object of the present invention is to provide an air mattress suitable for use in backpacking in which repair or reconstruction of the mattress can be easily accomplished.
The air mattress and method of the present invention have other objects and features of advantage which will become apparent upon consideration of the following detailed description of the preferred embodiment and the accompanying drawings.
SUMMARY OF THE INVENTION
The inflatable air mattress of the present invention is comprised, briefly, of a very lightweight casing having a plurality of side-by-side pockets formed therein and dimensioned for receipt of a plurality of inflatable elements. In addition, a plurality of relatively small diameter inflatable members are removably mounted in the casing and formed from a thin-walled, lightweight material. The inflatable elements are inflated until fully distended in order that the small diameter will give sufficient cushioning. The use of a plurality of small diameter elements, each of which is independent, inside a protective casing affords a mattress construction in which periodic puncturing of an element is contemplated and can be tolerated, enabling the use of lightweight, compact material. The elements are readily removable from the casing for repair or replacement, and tab means are provided for insertion of the elements into the casing. The valve in each inflatable element is formed to allow a positive pressure to be applied to the air inside the element while the valve is being closed to insure full distention and inflation of the elements.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of an air mattress for use for backpacking constructed in accordance with the present invention.
FIG. 2 is a top plan view of an inflatable member employed in the mattress of FIG. 1.
FIG. 3 is an enlarged, cross-sectional view taken along the plane of line 3--3 in FIG. 1.
FIG. 4 is an enlarged, cross-sectional view taken along the plane of line 4--4 in FIG. 2.
FIG. 5 is an enlarged, cross-sectional, fragmentary view taken along the plane of line 5--5 of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIGS. 1, 2 and 3, the lightweight, compact air mattress of the present invention can be seen to be comprised of a casing, generally designated 21, having opposed sheet portions 22 and 23 formed to define a plurality of side-by-side elongated pockets 24. Pockets 24 are preferably formed by stitching the upper and lower sheet portions 22 and 23 together along longitudinally extending lines 26, and the pockets are dimensioned for receipt of a plurality of inflatable tubular members.
In order to insure that the air mattress of the present invention is suitable for use for backpacking, casing 21 is formed of a very thin, high strength, lightweight material, such as woven nylon fabric. In the air mattress of the present invention, casing 21 does not function to prevent all punctures of the inflatable tubular members. Instead, the primary purpose of the casing is to hold the inflatable members in a mattress array and provide some limited protection against puncturing. Thus, "very thin" as used herein does not mean a sheet thick enough to prevent puncturing. Instead, the expression "very thin" as used herein shall mean a material having a thickness of no greater than about 0.006 inches. Furthermore, the term "lightweight" as used in connection with the casing material throughout shall mean a material having a weight in the range of about 1.2 to about 1.9 ounces per square yard. In this regard, it has been found highly advantageous to employ a woven nylon having a thickness of 0.003 inches as the casing material since it provides a certain degree of abrasion and puncture resistance, has sufficient strength to hold the inflatable tubular members in the desired mattress array, and has a weight in the desired range.
Removably mounted in pockets 24 of casing 21 are a plurality of elongated, inflatable tubular members 31. In order that the weight and bulk of the mattress of the present invention be reduced and further in order that adjacent elements can be in a position to give support, the inflatable tubular members each have a relatively small diameter cross-section and each tubular member is provided with its own valve means 32 for inflation thereof. Again, the tubular members are formed of thin, lightweight material and are mounted in openings in the casing 21 with valve means 32 accessible to the openings for inflation of the tubular members while in the casing. As shown in FIG. 1, casing 21 is provided with a zipper closure 27, allowing the end 28 of the casing to be selectively opened and closed to expose valves 32 for inflation and deflation.
Again, it is not the purpose of the present invention to form the inflatable tubular members of a material having sufficient strength or wall thickness to prevent puncturing. This approach, as above outlined, results in a mattress which is too heavy and/or bulky. Therefore, as used herein in connection with the inflatable tubular members the term "thin" shall mean a member having a wall thickness between about 0.005 inches and about 0.012 inches. Additionally, the expression "relatively small diameter" as used in connection with the inflatable tubular members of the present invention shall means members having an inflated cross-sectional diameter less than about 2.5 inches. The independently inflatable and deflatable nature of the plurality of tubular members, the small diameter cross-section, and the thin, lightweight material from which the tubular members are made, all combine to enable the formation of a lightweight, compact air mattress suitable for backpacking by functioning on the basic principle that puncturing of the inflatable elements will occur and can be tolerated. While other inflatable mattress constructions have recognized that puncturing can occur, they have gone to great lengths to prevent and minimize the possibility of puncturing. Thus, a plurality of layers of material or combinations of material and rubber have been employed to prevent puncturing. In the present invention, casing 21 is very lightweight, as are tubular members 31. Accordingly, the backpacker must expect that puncturing of a tubular element will periodically occur. When puncturing does happen, however, only a single element will normally be affected at any one time, and the small diameter of the tubular elements will cause the weight of the camper to be supported on closely adjacent members. A camper may, therefore, experience a puncture of an element in the middle of the night and still be comfortably supported on the adjacent elements throughout his night's sleep. In the morning, the camper will merely remove the punctured element and replace the same with a spare tubular element or merely patch or repair the damaged element with a simple repair kit. The reduction in diameter of the inflatable tubular members additionally has an attendant savings in bulk and weight. It has been found highly advantageous to form tubular elements 31 from polyvinyl chloride having a wall thickness of 0.008 inches. Polyvinyl chloride can be readily sealed along edges 33 (best seen in FIG. 4) by heat sealing equipment and valve means 32 can be readily incorporated into the polyvinyl chloride tube by heat sealing or adhesives to provide the inflatable member.
It is a further feature of the present invention to allow rapid insertion of replacement tubes or repaired tubes into casing 21 that each tubular member 31 be provided with a tab means 34 adjacent end 36 thereof. The tab is preferably formed for releasable engagement by an elongated rigid member such as by providing an opening 37 into which the end of a stick can be inserted. With the tubular member deflated, a willow stick, for example, can be inserted in opening 37 and used to push the tubular member down pocket 24 in the casing, after which the stick may be pulled from the pocket and the tubular member inflated.
Another important advantage of the air mattress of the present invention accrues by reason of the construction of the mattress with relatively small diameter tubular members, namely, the volume required to inflate and deflate the mattress of the present invention is relatively low. Much of the backpacking which occurs takes place in mountainous areas, and often at very high elevations. A standard air mattress may require five minutes or more inflation time at sea level, with this time being further substantially increased at higher elevations where the air is thinner. A backpacker does not want to spend 5 to 10 minutes inflating his air mattress if this can be avoided. Since the volume in a tubular mattress increases with the square of the diameter of the tubes, reduction of the tube diameter from the standard 5 or 6 inch diameter air mattresses to 2 inch or 2 and 1/2 inch diameter tubes results in a substantial time savings to the camper in inflating his mattress. Conversely, the plurality of independently inflatable and deflatable tubes and valves allows the air mattress of the present invention to be rapidly deflated. In standard mattresses, the entire volume of the mattress normally must pass out a single valve, and that volume is much greater than the mattress of the present invention.
In order to insure sufficient cushioning from the small diameter inflatable tubes of the present invention, the mattress should be inflated until tubes 31 are substantially completely inflated or distended. Because the volume of each individual tube is low, valve means 32 is preferably formed for operation from an opened to a closed position while a positive air pressure is maintained on the volume of air inside tubular member 31. One such valve construction is briefly illustrated in FIG. 5 and set forth in more detail in U.S. Pat. No. 2,859,932. Such a valve mechanism includes a reciprocal tubular element 41 having an opening 42 therein. The reciprocal element is mounted in a housing 43 having a frusto-conical seat portion 44 against which a mating frusto-conical surface 46 on the reciprocal element 41 can seat. In the position as shown in FIG. 5 air will pass down tubular element 41 out opening 42 and around surface 46 and out opening 47 to the interior of tube 31. To seal the valve, one may merely reciprocate element 41 until surfaces 46 and 44 mate at which point air cannot pass either into or out of the inflatable tubular member. Thus, the camper can blow the tubular member up until it is fully inflated and maintain a positive pressure on the air inside the tubular member while reciprocating the element 41 to closed position with his teeth. Other valve constructions which will allow the simultaneous maintenance of a positive pressure while sealing would include valves in which the sealing action occurs upon rotation of an element.
It is another feature of the present invention that the pockets in casing 21 defining opposite peripheral edges of the mattress and the tubular members mounted in such pockets may be of larger diameter than the tubular members intermediate of the edge defining pockets. As shown in FIG. 3, one tubular member 51 is formed of a larger diameter than the remaining tubular members. A second larger diameter tubular member would be provided at the opposite edge of the mattress to create a cradling effect tending to keep the camper's sleeping bag on the mattress. For simplicity of illustration, a large diameter tubular member is only shown on one side of the mattress with the opposite side illustrating pockets 24 with the tubular members removed therefrom. Since each of the tubular members in the mattress of the present invention are independently inflatable and deflatable, it would be possible for the camper to selectively determine whether or not to inflate element 51 to its distended diameter and create a cradling effect or only partially inflate element 51 and create a substantially level upper mattress surface.
EXAMPLE
A comparison of the mattress of the present invention with comparable foam rubber cushions and a standard rubber-fabric air mattress illustrates the advantages of the mattress construction of the present invention as employed by backpackers. The air mattress of the present invention is preferably constructed with eight or nine two-inch diameter inflatable tubes having a length of about 31/2 to 4 feet. As so constructed, the mattress will readily cushion or support the upper body of the camper. Support for the camper's legs is not usually required, and conventional air mattresses and foam rubber cushions often are constructed which are not full-length. 8 mil polyvinyl chloride tubing having heat sealed seams and a push-pull valve heat sealed therein was used to construct the mattress of the present invention. Table 1 set forth hereinbelow compares a mattress so constructed with comparably sized standard air mattresses and foam rubber cushions.
TABLE 1 ____________________________________________________________ ______________ Mattress Packing Volume (cubic inches) Weight Tube Diameter (thickness) (inches) Air Volume (cubic inches) Inflation Time (Deflation Time (minutes) ____________________________________________________________ ______________ 1. Standard rubber-fabric air mattress 300-325 4.5-5.0 lb. 5.5 5000-6000 5 or more 4 2. Foam rubber cushion 600-650 14-16 oz. 1.5 -- -- -- 3. Lightweight, small diameter tube-casing mattress 60-90 20-24 oz. 2.0 1000-1,200 2 or less 1.5 ____________________________________________________________ ______________
As will be seen from Table 1, the lightweight, small diameter mattress of the present invention occupies one-third to one-tenth of the volume which standard air mattresses or foam rubber cushions occupy in the backpack. The air mattress of the present invention weighs only about four ounces more than a foam rubber mattress, but it is 3 and 1/2 pounds or more lighter than standard rubber-fabric air mattresses. Thus, when compared to a foam rubber cushion, a 4 ounce weight increase allows a reduction in packing volume of almost 10 times. When compared to the standard air mattress, both the volume and weight are cut by a factor of at least three. It should be noted further that the weight and volume on the foam rubber cushion are probably optimistically stated since the cushion is only 1.5 inches thick while the air mattress of the present invention is 2 inches thick. This is significant since the foam rubber cushion having a thickness of only 1.5 inches does not afford the same comfort as the air mattress of the present invention.
A comparison of the volume of air in the air mattress of the present invention and the inflation and deflation times with the standard air mattress further reveals the substantial advantages of the small diameter, multiple tubed construction. In effect, the air mattress of the present invention allows the backpacker to have the comforts of the large, heavy standard air mattress, which comforts are not achievable by the relatively thin foam rubber cushion, without the attendant volume and weight disadvantages. Moreover, the use of thin, lightweight materials in which puncturing is contemplated and tolerable affords a mattress having a comparable weight to the lightweight foam cushion and a substantially reduced volume and increased comfort.