Discrete orthoganol support system
A “stratified” cushion assembly which can be used to support the human body under various conditions. The stratified cushion assembly generally includes alternating strata of supportive material, with each stratum having a different compression modulus than its adjacent strata. In the preferred embodiment the cushion assembly comprises alternating strata of visco-elastic memory foam and open-cell polyurethane foam. The strata are adhesively attached together with a foam adhesive.
1. Field of the Invention
This invention relates to the field of cushions. More specifically the present invention comprises a stratified cushion assembly which can be used to support the human body under various conditions.
2. Description of the Related Art
Many cushions and devices for supporting parts of the human body are known in the prior art. These devices come in many different designs and configurations. One example of such a device is described in U.S. Pat. No. 4,265,484 to Stalter (1981). Stalter describes a polyurethane formed body support member having a plastic reinforcing member and foam on either side of the plastic reinforcing member. The Stalter device utilizes the plastic reinforcing member to distribute the load evenly across the layer of foam under the reinforcing member.
Another cushioning device is exemplified by U.S. Pat. No. 5,294,181 to Rose et al. (1994). Rose et al. discloses a seat cushion made of layers of polyurethane foam, each layer having a different density. The Rose et al. device utilizes a sloping base layer to support an intermediate foam layer having a pair of laterally spaced recesses to accommodate the user's legs. A top layer having a range of protrusions and valleys is employed on top of the intermediate layer.
Other popular cushioning devices utilize visco-elastic memory foam to cushion and support the human body. Despite the growing popularity of visco-elastic foam, there are many disadvantages to using cushions made entirely of visco-elastic foam. First, visco-elastic foam is more expensive to manufacture than other foams. Second, cushions made of visco-elastic foam tend to “trench” around a user's body. This can make it difficult for the user to move around after sitting or lying in one place for an extended period of time. Finally, visco-elastic foam materials tend to trap heat and moisture more than other foams.
Many other cushions are known in the prior art, but are not discussed herein. Despite the existence of these types of cushions there remains a need for a low-profile cushion assembly that is supportive, comfortable, and that can be employed for a variety of cushioning applications.
BRIEF SUMMARY OF THE INVENTIONThe present invention comprises a “stratified” cushion assembly which can be used to support the human body under various conditions. The stratified cushion assembly generally includes alternating strata of supportive material, with each stratum having a different compression modulus than its adjacent strata. In the preferred embodiment the cushion assembly comprises alternating strata of visco-elastic memory foam and open-cell polyurethane foam. The strata are adhesively attached together with a foam adhesive.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
- 10 cushion assembly
- 12 middle layer
- 14 bottom layer
- 16 matrix
- 18 insert
- 20 cover
- 22 top layer
- 24 visco-elastic strata
- 26 open-cell strata
- 28 top layer
- W narrowest effective width
- H height
The present invention, cushion assembly 10, is shown in
Those that are skilled in the art know that a material's compression modulus is related to how “supportive” a material is, particularly a foam material. In the context of foam, the compression modulus relates to a foam's ability to support a force at different levels of displacement or compression. An approximation for a foam's compression modulus can be computed for a material by taking the ratio of the material's indentation force deflection (“IFD”) at 25 percent indentation (IFD25%) and 65 percent indentation (IFD65%) as shown in EQ. 1 below.
Compression Modulus for a Foam=IFD65%/IFD25% [EQ. 1]
Indentation force deflection is determined by taking the force in pounds required to indent or compress a piece of foam a specified percentage of its total height (typically a total height of 4 inches is used) with a surface area of 50 square inches. For example, a foam that has a IFD at 65% indentation of 100 pounds (meaning that the height is compressed 65% when subjected to a force of 100 pounds) and an IFD at 25% indentation of 50 pounds has a compression modulus of 2.0 (compression modulus values for polyurethane foam typically range from 1.8 to 3.0).
The compression modulus for polyurethane foam is a function of the density of the foam and the structure of the foam. Generally, the compression modulus increases as foam density increases. Also, different chemical formulations and manufacturing processes can be used to create foams with different cell structures. Foams with a high concentration of closed cells (closed-cell foam) typically have a higher compression modulus than foams with a high concentration of open cells (open-cell foam).
Returning to
A section view representation of the present invention is shown in
The functionality of each of the layers will now be considered in greater detail. Cover 20 and top layer 22 transmit and distribute the compressive load across the top surface of cushion assembly 10. The load is transmitted through top layer 22 to middle layer 12, and bottom layer 14. Inserts 18 act as the principal support means for top layer 22. Inserts 18, based on their geometry, tend to both compress and buckle when subjected to compressive loading. Matrix 16 both provides additional support against compressive loading and provides resistance against inserts 18's tendency to buckle. Inserts 18 are preferably adhesively bonded within matrix 16. The adhesive integrates insert 18 and matrix 16 so that the components of bottom layer 14 act in unison. The adhesive further provides additional resistance to the buckling of inserts 18. Although matrix 16 and the adhesive provide resistance to buckling, the controlled buckling of inserts 18 is desirable as will be explained subsequently. Middle layer 12 functions to distribute the compressive load across the surface of bottom layer 14 and prevents bottom layer 14 from tearing.
Example geometries for insert 18 are shown in
Other various angular or curvilinear cross-section geometries for insert 18 can be used, including but not limited to, triangular as shown in
The relationship and integration between the various components of the present invention will be now considered together. As described previously (and as illustrated in
It should be noted that visco-elastic memory foam materials possess physical characteristics that are different than most other foams. In particular, the “supportiveness” of a sample of visco-elastic memory foam is highly dependent on the temperature of the sample and the pressure exerted on the sample. As the sample is warmed, the foam provides less support.
As illustrated in
With the structure now described, the functionality of the embodiment of
The stratified assembly offers further advantages over that afforded by cushions made exclusively of visco-elastic memory foam. For example, visco-elastic foam cushions tend to “trench” around the user's body making it difficult for the user to move around after sitting or lying in one place for an extended period of time. Open-cell strata 26 help transition the load around the user's body so that the user does not get the feeling that he or she is “trapped” in a crater. The use of open-cell strata 26 also allows cushions to be manufactured with a greater depth (corresponding to height H illustrated in
In addition, the stratified assembly can be manufactured less expensively than current visco-elastic foam cushions since the stratified assembly uses approximately half the volume of visco-elastic memory foam as a conventional visco-elastic foam cushion. It has also been found that the proposed stratified assembly releases heat and moisture more quickly than cushions made entirely of visco-elastic foam. This is because open-cell strata 26 provide channels for air to migrate between visco-elastic strata 24. The movement of this transient air facilitates the flow of heat and moisture out of the cushion.
The preceding description contains significant detail regarding the novel aspects of the present invention. It should not be construed, however, as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. As an example, inserts 18 can be spaced throughout matrix 16 in various configurations. Inserts 18 are presented in a simple grid format in
Claims
1. A cushion assembly comprising: a stratified foundation having alternating strata of support materials, said alternating strata of support materials including a first series of strata comprising a first support material and a second series of strata comprising a second support material, said first support material having a different compression modulus than said second support material, said alternating strata of support materials bonded together in a common horizontal plane such that each of said first series of strata is bonded to at least one of said second series of strata.
2. The cushion assembly of claim 1, further comprising a top layer of support material bonded to said stratified foundation such that top layer of support material is bonded to both said first series of strata and said second series of strata.
3. The cushion assembly of claim 1, said first support material comprising visco-elastic memory foam.
4. The cushion assembly of claim 1, said second support material comprising open-cell polyurethane foam.
5. The cushion assembly of claim 3, said second support material comprising open-cell polyurethane foam.
6. The cushion assembly of claim 1, wherein when said first series of strata and said second series of strata are arranged in said common horizontal plane, each of said first series of strata and said second series of strata have a height and a narrowest effective width, said height greater than said narrowest effective width.
7. The cushion assembly of claim 1, wherein said alternating strata of support materials are bonded together with foam adhesive.
8. A cushion assembly comprising: a first series of strata comprising a first support material and a second series of strata comprising a second support material, said first support material having a different compression modulus than said second support material, said first series of strata and said second series of strata bonded together in a common horizontal plane such that each of said first series of strata is bonded to at least one of said second series of strata.
9. The cushion assembly of claim 8, wherein each of said first series of strata and said second series of strata comprise a substantially rectangular strip of foam material, having a first side face and second side face, said first side face and said second side face facing in opposite directions and having a height; wherein said first side face of each of said first series of strata is bonded to said second side face of one of said second series of strata, and said first side face of each of said second series of strata is bonded to said second side face of one of said first series of strata; each of said first series of strata separated from a neighboring one of said first series of strata by a width; wherein said height is greater than said width.
10. The cushion assembly of claim 8, further comprising a top layer of support material bonded to both said first series of strata and said second series of strata.
11. The cushion assembly of claim 18, wherein said first series of strata and said second series of strata are bonded together with foam adhesive.
12. The cushion assembly of claim 8, said first support material comprising visco-elastic memory foam.
13. The cushion assembly of claim 8, said second support material comprising open-cell polyurethane foam.
14. The cushion assembly of claim 12, said second support material comprising open-cell polyurethane foam.
15. A cushion assembly comprising: alternating strips of a visco-elastic memory foam and a second foam bonded together in a common horizontal plane, said cushion assembly configured to support a load applied perpendicularly to said common horizontal plane.
16. The cushion assembly of claim 15, said second foam comprising an open-cell polyurethane foam.
17. The cushion assembly of claim 15, wherein said visco-elastic memory foam and said second foam are bonded together with a foam adhesive.
Type: Application
Filed: Apr 19, 2007
Publication Date: Sep 13, 2007
Inventor: John Clark (Tallahassee, FL)
Application Number: 11/788,281
International Classification: A47C 27/00 (20060101);