Inflatable Foam Pad

Abstract

A pad and a method of making same with a combination resilient foam and fluid compression; using open-cell foam encased in and bonded to an impervious envelope and a valve communicating with the interior of the envelope for passage and containment of the fluid. The pad is also used as a structural member when the fluid is pressurized.

Description

BACKGROUND OF THE INVENTION

Several types of pads or cushions are used for camping mattresses. Most common is the air mattress which is usually made by bonding two sheets of reinforced rubber or plastic together in a pattern such that when the mattress is pressurized with air a series of parallel tubes is obtained. The bonding effecting points of tension to confine and define the shape of the inflated mattress. Air mattresses must be inflated by mouth or pump and the mattress has poor insulating qualities because of the single air gap.

Plastic or rubber foam provides good insulation when used for camping mattresses, but the required density of foam makes the mattress bulky and heavy.

It was discovered that a self inflating, flat surfaced mattress having good insulating properties could be obtained by containing a one piece resilient open-cell foamed material inside an impervious envelope and utilizing a valve in communication with the inside of the envelope to control fluid therein.

It was also discovered this article serves as a structural member when the fluid inside the envelope is pressurized before being contained. One of the better means for obtaining an inflatable structural part has been to use a flexible bag having parallel skins which are held together by a multitude of threads fastened between the skins to serve as tension members when the bag is pressurized. The instant invention places the resilient foam in tension to define the inflated structure.

SUMMARY OF THE INVENTION

A self inflating pad capable of being adjusted to control its firmness is obtained with a resilient foam, a fluid tight film or skin forming an envelope around the foam and a valve for communicating with the inside of the envelope. The foam should be of a resilient material and have a multitude of interconnecting interstices to allow free movement of fluid within the foam. The envelope should be of a flexible material that is fluid tight. The valve extends through and is bonded to the envelope to effect communication with the inside of the envelope and to allow fluid to be introduced, removed or retained. The foam is bonded to the inside of the envelope to form the pad; thus when pressurized fluid is trapped inside the pad the foam is placed in tension and the shape of the foam determines the shape of the pad. Therefore, the surface may be essentially flat. The cushioning effect or in other words the firmness may be controlled by the compressibility and extensibility of the pad and the amount of fluid within the envelope. The valve allows adjustment of the fluid volume. A pad of this configuration with a gas such as air as the fluid provides good thermal insulating characteristics because of the multitude of air spaces.

The pad may be of a very light weight as the foam is loaded mainly in tension, holding the skins together rather than depending solely on its crushing strength. The foam acts as a compression member in areas of a direct load and as a tension member in areas removed from a direct load. Tensioning of the foam remote from the area of compression causes the pressure to rise in the pad, further resisting the local compression.

This pad, due to the low density highly compressible foam and the flexible envelope may be readily compressed until flat by opening the valve to permit air to be expelled while the pad is being compressed. If the valve is closed while the pad is under compression the pad remains compressed until the valve is opened. Several mattress sized pads may be thus compressed and packaged together for effecting a space savings while in transit or in storage. If one chooses the pad may be flattened and rolled and upon closing the valve will stay in the compressed rolled shape until the valve is opened. To inflate it is neccessary only to open the valve which allows air to enter and self inflate the pad due to the resilience of the foam as it returns to its original size and shape. Close the valve to hold the air in and the pad is ready for use. If desired, the firmness of the pad may be adjusted by blowing or pumping a small amount of air inside to increase firmness or by squeezing to exhaust some air before closing the valve to reduce firmness.

When the fluid in the pad is a liquid such as water the buoyancy of the pad is supplemented by the weight of the liquid displaced. As with the gas-filled mattress the foam loads in tension to increase internal pressure, this allows the use of a much thinner pad for a given cushioning requirement than a water bed. The foam damps much of the wave action due to the viscous effect of the water flowing through the interstices of the pad.

When the fluid in the pad is introduced under pressure and the valve closed to contain the pressure the pad acts as a structural member. The foam is placed entirely in tension and the internal pressure resists general or local deformation and buckling of the skins. For structural applications the pad must be open-celled but may or may not be resilient.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an inflatable pad.

FIG. 2 is a perspective view of a deflated and rolled up inflatable pad.

FIG. 3 is a partial sectional view of an inflated pad taken along section 3--3 of FIG. 1.

FIG. 4 is a partial sectional view of a deflated pad taken along section 4--4 of FIG. 1.

FIG. 5 is a partial sectional view of an inflated pad with valve taken along section 5--5 of FIG. 1.

FIG. 6 is a perspective view of a corner section of an inflated pad showing a lap type of joint for joining the skins.

FIG. 7 shows a fragmented side elevation of a fabric reinforced skin.

DETAILED DESCRIPTION

The details of an inflatable pad 10, as practiced by this invention is best illustrated in FIG. 5. Referring then to FIG. 5 one finds a flexible fluid-tight envelope 12, in the form of a membrane or skin, encasing a resilient foam 14, having a multitude of interconnecting interstices, now shown, and a valve 16. The envelope and the foam are bonded together at interface 17. Any open-cell foamed resilient material such as polyurethane, plasticized polyvinylchloride and rubber may be used, but the polyurethane foam is preferred. The fluid-tight skin may be of a flexible polyurethane, plasticized polyvinylchloride, natural rubber, neoprene (polychloroprene) rubber, Tedlar (polyvinyl fluoride) or Hypalon (dichlorosulfonated polyethylene). The bond may be accomplished by use of an elastomeric adhesive of a polyurethane, nitrile or neoprene base. When both the foam and the envelope are polyurethanes a bond may be obtained by the application of heat at about 300.degree. to 450.degree. Fahrenheit. In the drawings the skins may be reinforced by a fabric such as nylon, polyester, or cotton, with nylon preferred. These fabrics are named by way of example and are not intended to be limiting.

In one preferred embodiment the open-cell foam is a resilient polyurethane of from about 0.5 to 1.5 pounds per cubic foot and from 1 to 6 inches thick. A skin of Hypalon rubber impregnated nylon cloth of from about 0.0015 inches to about 0.015 inches in thickness is coated with a neoprene base contact cement and is applied to the upper and lower surfaces of the open-cell resilient polyurethane foam 14, and the surfaces of the skin that extend beyond the foam are pressed together and sealed in a tee type joint as at 18, FIG. 3 and FIG. 4.

Valve 16, may be any of the conventional types such as a tube and plug, tube and cap, flexible tube folded over and fastened in folded position, or a screwed or spring poppet or globe valve. In one preferred embodiment, best shown in FIG. 5, the valve has tube 20, having a large internal diameter sized according to the thickness of the pad 10. The thicker the pad the larger the diameter. Even larger tubes may be used if installed on the flat surface of the pad. The size of this tube controls the time for compressing and for inflating the pad 10. The inside end of the tube in this embodiment is cut on a bias 22, to allow for maximum flow area at the interface between the foam and the tube. The tube may be of a polyvinyl chloride, neoprene, Hypalon, metal, or polurethane with polyurethane preferred when used with the polyurethane skin. Removable stopper 24, in one preferred embodiment has a second tube 26, extending through with a second stopper 28. The second tube and stopper form a valve within a valve, and when the second stopper is removed it allows for a fine adjustment when introducing or removing a fluid to easily control the cushioning effect of the pad. The second tube may be lengthened and may be of a flexible material to allow pinching to further restrict flow of fluid to obtain an even finer adjustment. The materials for the two stoppers and the second tube are not critical. In this embodiment stopper 24, was neoprene, tube 26, was polyvinylchloride and the stopper 28, was metal. A chain or cord 30, is used to prevent losing the stoppers.

In another preferred embodiment the foam 14, is an open-cell resilient polyurethane. The skin with a coated reinforcing fabric is best shown in FIG. 7 where skin 12 has reinforcing fabric 32 and flexible impervious coating 34a and 34b. The skin 12, is a nylon fabric coated or impregnated with a flexible polyurethane. The foam is placed between the skins, compressed, the skins pulled taut, and the surfaces of the skins extending beyond the foam are heat sealed together. Next the compression is removed and heat applied to the area of the skins in contact with the two largest surface areas of the foam to bond the skins to the foam. The heat may be applied by platens, rollers, an iron or by hot gases. In this embodiment an iron at about 350.degree. was applied for about 15 seconds to effect a good bond. A small area of the surfaces of the skins extending beyond the foam was left unbonded and a valve with a polyurethane tube was heat sealed between the skins in that area.

In one preferred embodiment the foam is compressed about 75 to 90 percent before sealing the extending surfaces of the skins and the skins are sealed with a tee type of joint as shown in FIG. 3. This facilitates rolling the pad.

In yet another preferred embodiment the foam is compressed about 20 percent before sealing the extending surfaces of the skins and the skins are sealed with a lap type of joint 32, as shown in FIG. 6.

Due to the advantages of the resilient open-cell polyurethane foams a series of samples have been made and evaluated using various skin materials.

EXAMPLE 1

A four inch by six inch pad one inch thick was made using 0.9 pound per cubic foot open-cell resilient polyurethane foam (Caliform production code 0909CM) and 0.0015 inch thick Tedlar coated nylon balloon cloth. The valve was of 3/16 inch vinyl tubing plugged with a piece of metal. The bonding was accomplished with A. B. Boyd neoprene cement, type B1. This sample displayed good rollability and cushioning characteristics. It was not tested as a liquid filled pad.

EXAMPLE 2

A 13 inch by 19 inch sample was made with 1 inch thick, 0.9 pound per cubic foot open-cell resilient polyurethane foam, an envelope made up from a skin of 0.004 inch thick Hypalon rubber impregnated nylon cloth (Duracoat Corp. 600-11H Form A) and a 1/4 inch vinyl tube and 3M contact cement number 2215 (a neoprene base adhesive). This sample had a soft feel and had good resistance to damage.

When filled with water the cushioning effect was similar to that when filled with air except that when compressed it had a viscous lag probably due to the resistance of the foam to the flow of water.

EXAMPLE 3

A sample 5 inches by 7 inches was made with the same type of polyurethane foamed material as in example 2 and with an envelope of dental dam material which is pure nature rubber 0.010 inches thick. This was bonded with the neoprene rubber base adhesive (3M contact cement numbr 2215). This sample was very soft as the natural rubber stretches easily. This pad when filled with water most nearly resembled the characteristics of the water bed. The damping effect of the foam strongly affected the wave action resulting from a sudden deformation.

EXAMPLE 4

A 2 foot by 6 foot pad was prepared using the same materials for the foam and the flexible envelope as in example 2. A rigid 3/4 inch internal diameter polyurethane tube was used and fitted with a stopper having a 1/4 inch vinyl tube inserted for fine adjustment of internal air quantity and pressure. Metal was used as a plug for the 1/4 inch tubing.

The cushioning and rolling characteristics were very good. The pad rolled to a 31/2 inch diameter. The compression thickness of the pad was only 0.050 inches but the wrinkling of the inner skin prevented full compression of the roll. After being rolled for several days the large stopper exposing the 3/4 inch tube was removed and the pad self inflated within two minutes.

EXAMPLE 5

A pad 20 inches by 72 inches was prepared using a 11/2 inch thick 0.9 pound per cubic foot open-cell resilient polyurethane foam, the flexible skin for the envelope was a one ounce per square yard nylon impregnated with 31/2 ounces per square yard of a polyurethane rubber and a 3/4 inch inside diameter rigid polyurethane tube with stopper for the tube. The foam was bonded to the skins by heat sealing with a household iron. The foam was placed between taut skins, the foam compressed and the surfaces of the skins extending beyond the foam were heat sealed. Compression forces were removed from the foam and the foam was heat sealed at its upper and lower surface to the stretched skins. The valve assembly extended through and was heat sealed to the fluid impervious skins.

A high strength fluid impervious bond was obtained.

This 11/2 inch pad was very comfortable when used as a camping mattress.

EXAMPLE 6

A 4 foot by 6 foot by 4 inch pad was built using materials as described in example 2, except a neoprene tube was used in place of vinyl. This pad had a comfort level appropriate for a home or a therapeutic mattress as the firmness was easily changed by controlling the amount of air inside the pad.

EXAMPLE 7

A 21 inch by 16 inch pad was prepared using a 2 inch thick, 1.5 pound per cubic foot open-cell resilient polyurethane foam and an envelope from skins as in example 5. An automobile tire valve was bonded to the envelope and 5 p.s.i. of air was introduced into the pad. A 20 pound load placed in the middle of the pad when supported on 18 inch centers deflected 1/2 inch. A 2 pound load caused the same amount of deflection when the test was repeated with zero pressure inside the envelope. When the pad was placed on edge it buckled at 6 pounds of load with zero pressure inside and at 130 pounds of load with 5 p.s.i. of internal air pressure. The top skin of a pad with 5 p.s.i, of internal air pressure deflected about 3/8 inch when placed on the floor and stepped on by a 150 pound man.

Claims

We claim:

1. A pad comprising: a resilient foamed open-celled material, having a density of from about 0.5 to 1.5 pounds per cubic foot; a pair of taut skins, of reinforcing fabric coated with flexible fluid tight material, covering and bonded to the foamed material to form an envelope with the surface of the skins that extend beyond the foamed material joined together; and a first valve communicating with the inside of the envelope through which a fluid may be introduced, removed or retained, said valve having a diameter sized to the thickness of the foamed material to permit rapid movement of fluid therethrough, and a second smaller valve within the first valve comprising an extended flexible tube having a stopper to allow for fine adjustment of the fluid flow therethrough.

2. A pad as in claim 1 further comprising a tee type joint between the extending surfaces of the skins.

3. A pad as in claim 2, wherein the fluid is water.

4. A pad as in claim 2, wherein the fluid is air at a pressure of at least 5 p.s.i.

5. A pad as in claim 1, further comprising a lap type joint between the extending surfaces of the skins.

6. A pad as in claim 5, wherein the fluid is water.

7. A pad as in claim 5, wherein the fluid is air at a pressure of at least 5 p.s.i.

8. A self inflating pad capable of being compressed and retained in the compressed state for space saving in transit or in storage comprising: a resilient foamed material of about 0.5 to 1.5 pounds per cubic foot, having a multitude of interconnecting interstices; a pair of flexible fluid tight taut skins covering and bonded to the foamed material to form an envelope with the surface of the skins extending beyond the foamed material joined all around in a tee type joint; the resilience of the foamed material, the flexibility of the taut envelope and the tee type joint allows the pad to be compressed; and a valve within a valve communicating with the inside of the envelope permits air to be expelled from the pad during compression while the valve is open, prevents air entering the compressed pad when the valve is closed, allows air to enter and self inflate the compressed pad to the resilience of the foamed material when the valve is open, and holds the air in and the inflated pad firm when the valve is closed, said valve within a valve further comprising; a tube bonded to the envelope and having one end of the tube inside the envelope and the other end outside the envelope; a removable first stopper for the tube, having a plugged hole therethrough, said plug comprising a flexible tube inserted into and extending beyond the first stopper; and a second removable stopper in the flexible tube such that removal of the second stopper gives fine adjustment of fluid flow and removal of the first stopper gives maximum fluid flow.