Adjustable foam mattress

Abstract

The invention modulates the air volume in foam cores of cushioning support devices and any other support apparatus using foam or similar materials. The foam core can be incrementally modulated to realize an infinite number of comfort levels as to softness and support firmness. The core consists of self-inflating open-cell flexible polyurethane foam and is completely sealed within an enclosure fitted over it, with one or more valves installed in the side walls which communicate with the outside air. Through the valves air is selectively withdrawn from the foam core, allowing the foam's density to increase. The invention uses relatively inexpensive foam, but through air volume modulation achieves a tactile feel of supreme softness for the user, without giving up the necessary firmness to support the body, as happens with very soft foam (bottoming-out or hammock-effect). When air is extracted from a self-inflating foam core, the surface of the core will soften uniformly while maintaining its support firmness. Contrary to this, when pressure is exerted on, for example, traditional coil spring core mattresses, their surface will harden. Integral part of the invention is a device using balanced springs in valve assemblies to avoid compression set, an irreversibly solid state of totally air-depleted foam.

Description

RELATED APPLICATION [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 244,456 filed Sep. 17, 2002 issued on Aug. 2, 2005 as U.S. Pat. No. 6,922,863.FIELD OF THE INVENTION [0002] The present invention teaches the modulation of the principal characteristics of open-cell, flexible polyurethane foam for use in support devices such as mattresses, sifting furniture, cushions and all other applications using a support apparatus. These characteristics are subjective tactile softness and bodyweight-carrying support firmness, the modulation of which is effected in a way so as to greatly enhance comfort and to offer an infinite choice of easily adjustable levels of comfort to the user at lower comparable cost. On its own, in combination with multi-chamber arrangements and also integrated with known, traditional techniques, this invention enhances the versatility of support devices, allowing for a great number of variations in the choice and adaptation of material...

AI Technical Summary

Benefits of technology

[0020] The present invention teaches how to control and modulate the principal characteristics of open-cell flexible polyurethane foam in a specific integration with airtight covers and pressure valves for the use in any form of comfort support device, for instance, mattresses. The principal characteristics pertain to industry standards of subjective tactile softness in the sense of espousing body contours so as to optimally distribute pressure points of a person reclining on a planar surface, and of bodyweight-carrying support firmness. They are controlled and modulated in a way to not only greatly enhance comfort, but particularly to offer an infinite choice of easily adjustable levels of comfort, defined as a balance between softness and firmness. This is done at lower comparable cost and weight compared to high density foam varieties such as visco-elastic foam, and in combination with known, traditional techniques, it enhances versatility, allowing for a great number of variations in the choice and adaptation of materials to go together with self-inflating, modulable foam into comfort level adjustable support devices.

[0021] The invention teaches how the Indentation Force Deflection (IFD) and density properties of a certain quality range of flexible open-cell polyurethane foam are modulated by removing some of the air from within the foam cells and altering the cellular density of the foam core. Since high density, more expensive foams, such as visco-elastic foams, are very desirable as to comfort, the principal teaching of the invention is how to modulate comparatively less expensive, lower density foam to exhibit the feel-characteristics of high density foam, and also attain support and comfort levels of a higher density, more expensive foam, without locking the user into a single, fixed comfort level.

[0022] IFD and density modulation are achieved by altering open-cell, flexible polyurethane foam or material of similar characteristics within a fixed framework of controllable valves and airtight bladders. This art teaches that the material is fashioned in a particular form and that it is of a molecular composition as to permit the extraction of air in the alveolate structure in a uniform manner throughout, thus increasing material density equally uniformly. A further specialty of the material is that, by virtue of its structure, particular manufacturing and finishing processes, it affords in its low IFD number modulated state a commensurably higher support stability, heretofore only associated with foam or similar material of a very much higher density and greatly higher price. Finally, it is much lighter in weight than the latter and can also be reduced in size and volume for easy transport and storage.

[0023] The application of the principles of this teaching extends to a great number of possible combinations of foam only and foam plus traditional support devices used in the architecture of, for example, mattresses, that users may adjust to their personal preference. But in all its combinations, the pivotal point of the invention is that specifically fashioned types of foam will soften when air is extracted from their cell structure. Compared to its original firmness, which is indicated by the manufacturer's IFD number, its resilience will decrease to about half of its original value. The density on the other hand increases considerably to about double its original value, creating the much needed body support a mattress should have. Density of foam is its weight per cubic foot, hence the heavier a cubic foot of foam weighs, the higher will be its density rating.

[0024] The present invention teaches that removing air from a foam core uniformly reduces the volume of the core, hence increases its density without adding weight to the overall mattress, which would be undesirable for the user. One of the disadvantages of high density foams, such as visco-elastic foam, is that they are very heavy and difficult to fashion in the form of a mattress. In this invention the single foam core mattress as well as its combination with other bedding materials are much lighter of weight but yet exhibit the same comfort and support characteristics as, for instance, a visco-elastic mattress. It has the additional advantage of being adjustable. Removing air from visco-elastic foam or similar materials in the same manner is not possible, because their cellular structure is very tight and would solidify almost immediately (densification).

[0028] The chamber's vacuum in this example is controlled by valves which operate under spring pressure. When air is evacuated from a self-inflating foam core within a hermetically sealed cover, the foam material's cellular elasticity exerts pressure to expand to its original form by drawing air back into its open cells, developing a measurable suction force. The more air is removed from the foam cells, the higher the foam core's re-inflation force. Springs in the valve assemblies connected to the partially emptied chamber oppose the re-inflation force reciprocally. Hence a balance between the opposing forces can be established, depending on the spring force and the suction force. Tests conducted in a laboratory environment show that CS can be prevented in a totally deflated foam core if the re-inflating force is slightly greater than the closing force of the valve spring. In this manner, air is drawn back into the mattress at a very slow rate, and stops entering the mattress when the re-inflation force of the foam equals the compression force of the spring in the valve. A fixed spring-force setting, allowing foam to re-inflate to a specific degree greatly reduces the occurrence of CS and preserves the deflated product from malfunctioning when allowed to re-inflate after extended storage periods. The principle of residual air retention to off-set CS has been validated in laboratory experiments for polyurethane foam used in a wide variety of mattress architectures, be it by itself or in a combination with other arrangements. To balance the closing force of the valve spring within the valve assembly against the re-inflating force of the various foams, a great number of specific compression values are being used to adapt to foams having different IFD and density ratings.

Problems solved by technology

This process is inconvenient, since bulky foam components have to be stored and manipulated very often to make the required changes.

Another dilemma with “foam zones” having different IFD ratings for different parts of the body, is that it is difficult to give adequate support to a very soft foam component.

However, the high cost, bulk and heavy weight of a visco-foam core remains a problem.

Arpin discloses a method of increasing the firmness of metal coil springs by compressing these, which does not increase comfort.

Firmness (IFD) or density can not be modulated freely because of the thinness and light weight of the foam core used in camping mats.

Furthermore, compressing the camping mat by hand does not expel the air uniformly from all the foam cells but only in the area which are compressed by hand.

The problem with pressurized air supported surfaces is that if air were allowed to escape the pressurized chamber, the support surface would collapse and cause a hammock effect.

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