Patent Application
20160255964
The present invention relates to springs and mattresses including springs. In particular, the present invention relates to variable resistance springs which exhibit a non-linear response when compressed.
Typically, when a uniaxial load is applied to a spring, the spring exhibits a linear compression rate. That is to say, it takes twice as much force to compress a typical spring two inches as it does to compress the same spring one inch. The linear response of springs is expressed by Hooke's law which states the force (F) needed to extend or compress a spring by some distance (D) is proportional to that distance. This relationship is expressed mathematically as F=kD, where k represents the spring constant for a particular spring. A high spring constant indicates that the spring requires more force to compress, and a low spring constant means the spring requires less force to compress.
Spring rate is another well-known value used to categorize springs. The spring rate of a particular spring is the amount of force needed to compress a spring one inch. Springs with a high spring constant also have high spring rates, and springs with low spring constants have low spring rates. Of course, the spring constant and spring rate values are merely an approximation of the real response of a given spring; however, they are an accurate approximation for most springs given reasonable distance (D) values in comparison to the overall dimensions of the spring. Furthermore, Hooke's law applies for a variety of different spring shapes, including, for example, a coil spring, a cantilever spring, a leaf spring, or even a rubber band.
Linear response springs, such as wire coil springs, are commonly used as mattress innersprings in combination with padding and upholstery that surround the innersprings. Most mattress innersprings are comprised of an array of wire coil springs which are often adjoined by lacing end convolutions of the coil springs together with cross wires. An advantage of this arrangement is that it is inexpensive to manufacture. However, this type of innerspring provides a firm and rigid mattress surface.
An alternative to an innerspring mattress is a mattress constructed of one or more foam layers. Unlike an innerspring comprised of an array of wire coil springs, foam mattresses exhibit a non-linear response to forces applied to the mattress. In particular, a foam mattress provides more support as the load increases. For instance, a typical foam mattress provides increased support after it has been compressed approximately 60% of the maximum compression of the foam. The non-linear response of foam mattresses provides improved sleep comfort for a user. However, the mechanical properties of foam degrade over time affecting the overall comfort of the foam mattress. Furthermore, foam mattresses are more costly than metal spring mattresses.
The present invention relates to springs that provide variable resistance as the spring is compressed. In particular, the present invention relates to variable resistance springs that are extruded as a single unit and used within a mattress to provide a user positioned on the mattress increased support for portions of the user's body where a higher load is applied to the mattress. Thus, the mattress of the present invention provides a user the non-linear support typically seen in a foam mattress, but through the use of springs.
In one exemplary embodiment of the present invention, a spring includes a plurality of spring elements that are stacked atop one another, each spring element comprising a curved upper member and a curved lower member connected to the curved upper member, such that a concave side of the upper member and a concave side of the lower member define an internal space of the spring element. The spring further includes one or more spring stops positioned within the internal space of one or more of the spring elements.
Each spring element of the exemplary spring acts as a compression spring, such that a force applied to the upper member of the spring causes the upper member to move toward the lower member. Specifically, a force applied to the upper member of a particular spring element causes the upper member and the lower member to partially flatten out, and the internal space of the spring element becomes narrower. When the force is removed from the spring element, both the upper and lower members return to their original shape and position. To this end, the upper and lower members of the spring elements are comprised of a material which allows the upper and lower members to flex when the spring element is compressed, but still provide a biasing force to return the spring element to its original shape.
Each of the plurality of spring elements is connected to an adjacent spring element at a middle portion of the upper member or a middle portion of the lower member. For example, a bottom spring element is connected to the adjacent spring element at the middle portion of the upper member of the bottom spring element, whereas a central spring element is connected to adjacent spring elements at both the middle portion of the upper member as well as the middle portion of the lower member.
The spring stops of the present invention are positioned within the internal space defined by one or more of the spring elements, and such spring stops are configured to prevent the respective spring elements from compressing past a predetermined compression distance. In some embodiments, the spring stops are connected to (and integral with) a middle portion of the concave side of the lower member of the spring element. In some embodiments, each spring stop is a different size, such that the predetermined compression distance is different for each of the spring stops.
In operation, the plurality of spring elements function as a set of springs in series. When the spring is compressed, each spring element compresses simultaneously, unless a spring stop prevents the particular spring element from compressing further. By providing spring stops of different sizes, each spring stop engages its respective spring element at different compression distances of the spring. Accordingly, as the force applied to the spring increases and the compression distance of the spring increases, the number of active spring elements decreases, and the effective spring constant of the spring increases. As the spring constant increases, the spring rate also increases and the spring becomes “harder.” Thus, the spring of the present invention provides a non-linear response to loading.
In some embodiments, the spring also includes a vertical extension that is positioned between two spring elements. Such a vertical extension provides greater spacing between the two spring elements. Including such a vertical extension in the spring provides a point of flexure in the spring for when the spring is asymmetrically loaded, such as would be experienced when the spring is used in an innerspring for a mattress.
In another embodiment of the present invention, a mattress includes a plurality of the exemplary springs of the present invention. The springs are arranged in a matrix, such that a top engagement surface defined by the springs forms a first support surface, and a bottom engagement surface defined by the springs forms a second support surface opposite the first support surface. The mattress also comprises an upper body supporting layer positioned adjacent to the first support surface, along with a lower foundation layer positioned adjacent to the second support surface. Furthermore, a sidewall extends between the upper body supporting layer and the lower foundation layer, and around the entire periphery of the two layers, such that the springs are completely surrounded.
Further features and advantages of the present invention will become evident to those of ordinary skill in the art after a study of the description, figures, and non-limiting examples in this document.
The present invention relates to springs that provide variable resistance as the spring is compressed. In particular, the present invention relates to variable resistance springs that are extruded as a single unit and used within a mattress to provide a user positioned on the mattress increased support for portions of the user's body where a higher load is applied to the mattress. Thus, the mattress of the present invention provides a user the non-linear support typically seen in a foam mattress, but through the use of springs.
Referring to
Referring to
Accordingly, the upper and lower members 30a-f, 40a-f are comprised of a material which allows the upper and lower members 30a-f, 40a-f to flex when the spring element 20a-f is compressed, but still provides a biasing force to return the spring element 20a-f to its original shape. For example, the upper and lower members 30a-f, 40a-f may be comprised of rubber, plastic, metal, or other similar material that exhibits elastic deformation. Furthermore, in this exemplary embodiment, the spring 10 is illustrated as a unitary member, which could be manufactured, for example, by molding or extruding a thermoplastic material.
In view of the manner in which the spring elements 20a-f move in response to the application or removal of a force, each upper member 30a-f and each lower member 40a-f of the spring elements 20a-20f may be characterized as a leaf spring. The upper members 30a-f are downward-facing leaf springs, and the lower members 40a-f are upward-facing leaf springs. In these particular embodiments, the entire spring 10 can thus be considered a vertical stack of alternately stacked upward and downward-facing leaf springs.
Referring still to
Referring still to
Referring now to
When the exemplary spring 10 is uncompressed, as shown in
It is contemplated, however, that the exemplary spring 10 is configured such that the spring constant of each of the plurality of spring elements 20a-f is the same spring constant, K. Accordingly, equation (2) can be simplified, with the initial effective spring constant, of the spring 10 presumed to equal ⅙ of the spring constant, K, of the individual spring elements 20a-f.
Accordingly, when a first predetermined force, F1, is applied along Axis A of the spring 10, all of the spring elements 20a-f begin to compress simultaneously, and the spring 10 compresses at a constant spring rate according to the initial spring constant, K1, until the spring 10 has compressed a first predetermined distance, D1, as shown in
For compression distances past the first predetermined distance, D1, the spring 10 will compress according to a second effective spring constant, K2, of the spring. The second spring constant, K2, is based on the combination of the spring constants of the remaining active spring elements 20b-f that are still capable of compressing (i.e., all of the spring elements except for the first spring element 20a). In the exemplary spring 10, where each of the plurality of spring elements 20a-f is configured with the same spring constant, K, the second spring constant, K2, is presumed to equal ⅕ of the spring constant, K, of the individual spring elements 20b-f.
When a second predetermined (and greater) force, F2, is applied along Axis A of the spring 10, all of the active spring elements 20b-f compress simultaneously, and the spring 10 will compress at a constant spring rate according to the second spring constant, K2, until the spring 10 has compressed a second predetermined distance, D2, as shown in
For compression distances past the second predetermined distance, D2, the spring 10 will compress according to a third effective spring constant, K3 of the spring 10. The third spring constant, K3, is based on the combination of the spring constants of the remaining active spring elements 20c-f that are still capable of compressing (i.e., all of the spring elements except for the first and second spring elements 20a, 20b). In the exemplary spring 10 where each of the plurality of spring elements 20a-f is configured with the same spring constant, K, the third spring constant, K3, is presumed to equal ¼ of the spring constant, K, of the individual spring elements 20c-f.
When a third predetermined (and greater) force, F3, is applied along Axis A of the spring 10, all of the active spring elements 20c-f compress simultaneously, and the spring 10 will compress at a constant spring rate according to the third spring constant, K3, until the spring 10 has compressed a third predetermined distance, D3, as shown in
For compression distances past the third predetermined distance, D3, the spring 10 will compress according to a fourth effective spring constant, K4, of the spring 10. The fourth spring constant, K4, is based on the combination of the spring constants of the remaining active spring elements 20d, 20e, 20f that are still capable of compressing (i.e., all of the spring elements except for the first, second, and third spring elements 20a, 20b, 20c). In the exemplary spring 10 where each of the plurality of spring elements 20a-f is configured with the same spring constant, K, the fourth spring constant, K4, is presumed to equal ⅓ of the spring constant, K, of the individual spring elements 20d-f. It should be noted that, in this exemplary embodiment, the fourth spring constant, K4, is thus twice the value of the initial spring constant, K1, of the spring 10 when all of the spring elements 20a-f were active.
Although not shown, as more force is applied along Axis A of the spring 10 in excess of the third predetermined force, F3, the fourth, fifth, and sixth spring elements 20d, 20e. 20f will simultaneously compress until the spring 10 reaches a maximum compression distance of the spring 10. In some embodiments, the maximum compression distance of the spring 10 occurs when the upper members 30d, 30e, 30f of the fourth, fifth, and sixth spring elements 20d, 20e, 20f are in direct contact with the respective lower members 40d, 40e, 40f, and there is a minimal, if any, internal space 22d, 22e, 22f defined by the fourth, fifth, and sixth spring elements 20d, 20e, 20f.
Referring again to
It should now be apparent that, by providing spring stops 50a-c of different sizes, each spring stop 50a-c engages its respective spring element 20a-c at different predetermined compression distances of the spring 10. In one particular embodiment of the present invention, the first spring stop 50a is sized such that the first predetermined distance, D1, is 2 inches, the second spring stop 50b is sized such that the second predetermined distance, D2, is 3 inches, and the third spring stop 50c is sized such that the third predetermined distance, D3, is 4 inches. However, each particular spring element 20a-f and spring stop 50a-c can be configured to provide a spring 10 with any preferred compression response. For example, the spring 10 may be configured such that the first predetermined distance, D1, is approximately 60% of the maximum compression of the spring, such that the spring 10 better mimics the support characteristics of a foam mattress.
With further respect to the size of spring 10 of the present invention, in certain embodiments, the dimensions of the spring 10 height can be analogous to what is observed in current metal springs which have a typical diameter between 50 mm to 80 mm, and which typically have a height ranging from about 250 mm to about 400 mm. However, these dimensions are based on height to base ratio limitations necessary to prevent a typical wire coil spring from becoming unstable. Due to its unique design, the spring 10 of the present invention is not limited by the same height to base ratio limitations of a typical wire coil spring and so it is also contemplated that the spring 10 may have a height to base ratio much greater than the ratio of a typical wire coil spring with dimensions outside of the ranges provided above.
It is also contemplated that the height of the spring slops 50a, 50b, 50c, in the spring 10 can also be tailored to provide a desired level of firmness in a mattress, such as the mattress described in further detail below. For instance, in producing a firm mattress, the spring stops 50a, 50b, 50c in the spring 10 can have a height that is closer to the overall pitch between each particular spring element 20a, 20b, 20c. In this regard, in a mattress where a person sinks further into the mattress, but gains support at a particular depth, such a mattress would have spring stop dimensions closer to one-half the pitch distance of a particular spring element. In other words, the height of each spring stop can readily be adjusted to produce a desired load deflection curve for an overall mechanical response of particular spring of the present invention.
Of course, the number of spring elements and spring stops may also be adjusted in order to develop the preferred compression response of the spring. Furthermore, in some embodiments, the spring stops may act as compression springs themselves. This may be accomplished by selecting a material for the spring stops which is itself compressible, or by forming the spring stops into a shape which would allow the spring stop to act as a compression spring. In such alternative embodiments, the spring constant of the spring would depend not only on which spring elements are currently engaged by the respective spring stops, but whether the particular spring stop is fully compressed itself. This provides yet another level of customization to further develop a preferred compression response of the spring.
Referring once again to
Referring once again to
Referring now to
It is contemplated that the upper body supporting layer 160 is comprised of some combination of foam, upholstery, and/or other soft, flexible materials well known in the art. Furthermore, the upper body supporting layer 160 may be comprised of multiple layers of material configured to improve the comfort or support of the upper body supporting layer 160.
It is also contemplated that the lower foundation layer 170 could be similarly comprised of some combination of foam, upholstery, and/or other soft, flexible materials well known in the art, such that the mattress 100 can function no matter which way it is oriented. However, in other embodiments, the lower foundation layer 170 is comprised of a rigid member configured to support the plurality of springs 10.
Referring still to
It is contemplated that the spring 10 shown in
One of ordinary skill in the art will recognize that additional embodiments are also possible without departing from the teachings of the present invention or the scope of the claims which follow. This detailed description, and particularly the specific details of the exemplary embodiments disclosed herein, is given primarily for clarity of understanding, and no unnecessary limitations are to be understood therefrom, for modifications will become apparent to those skilled in the art upon reading this disclosure and may be made without departing from the spirit or scope of the claimed invention.
