THE SAM

TECHNICAL FIELD

[00 J ] The present invention relates to springs and mattresses including springs. In

particular, the present invention relates to variable resistance springs which are comprised of a coiled wire aid exhibit a non-linear response when compressed.

BACKGROUND

(0002} 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 i does to compress the same spring one inch. The linear response of springs is

expressed by iooke's law which states that 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 require less force to compress,

|0003j 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 Sow 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 ^r s law applies to a variety of different spring shapes, including, for example, a coil spring, a cantilever spring, a leaf spring, or even a rubber hand.

[0004] Linear response springs, such as wire coil springs, are commonly used as mattress innersprings in combination with paddin 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 arrangemeivi is that it is inexpensive to manufacture. However, this type of innerspring provides a firm and rigid mattress surface,

[0005} An alternative to an innerspring. mattress is a mattress constructed of one or more foam layers. Unlike an innerspring mattress comprised of an array of wire coil springs, foam mattresses exhibit a non-linear response to forces applied to the mattress. In particular, a roam 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 loam mattresses provides improved sleep comfort for a user. However, the mechanical properties of certain foam ma degrade over time affecting the o verall comfort of the foam mattress. Furthermore, foam mattresses are often more costly to produce than metal spring mattresses,

SUMMARY

|0ΘΘ { 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 including a coiled wire with one or more spring stops attached and used within a mattress to provide a user positioned on the mattress increased support for portions of the user's bod where a higher load is applied to the mattress. Thus, the mattress of the present invention provides a user the nonlinear support typically seen in a foam mattress, but through the use of springs.

f0007J in one exemplar embodiment of the present invention, a spring is provided that includes a coiled wire having m upper end convolution, a lower end convolution opposite the upper end convolution, and a plurality of intermediate convolutions whic helically spiral, between the upper end convolution and the lower end convolution. The exemplary spring further includes one or more spring stops attached to and positioned at predetermined distances along the coded wire. Each of the spring stops are substantially cylindrical with a portion of the coiled wire extending through a longitudinal axis of each of the spring stops. In this way. each spring stop substantially surrounds a portion of the coiled wire with the radius of the cylindrical spring stop extending perpendicularly away from the coiled wire such that a portion of the spring stop is interposed between the convolution upon which the spring stop is positioned and the

immediately adjacent convolutions.

[0008] The spring stops are configured such that when the spring is compressed a

predetermined compression distance, the coiled wire compresses a certain distance before the convolutions adjacent to the spring stops engage the spring stops, at which point the spring stops maintain a distance between the convolution upon which the spring stop is positioned and the adjacent convolutions. That distance is based, in part, on the radius of the spring stop (i.e., the portion of the spring stop that is interposed between the convolution upon which the spring stop is positioned and the immediately adjacent convolutions), but also, in part, on the composition of each of the spring stops. In this respect, in some embodiments, an exemplary spring stop is compri sed of an elastomer, for example a rubber, which is sufficiently resilient to maintain such a distance and spacing throughout the life of the spring. In some embodiments, each spring stop is a different size, such that the distance between the convolution upon which the particular spring stop is positioned and the adjacent convolutions is different for each of the spring stops.

[0009 In operation, when the spring is compressed, the coiled wire compresses until one or more of the spring stops prevents a section of the coiled wire from compressing further (i.e., the section is inactive). By providing spring stops of different sizes, each spring stop engages a portion of the coiled wire at different compression distances of the spring. Accordingly, as the force applied to the spring increases and the compression distance of the spring increases, more of the coiled wire becomes inactive, and the effective spring constant of the spring increases. As the spring constant -increases, t he spring rate also increases and the spring becomes "harder." Thus, the .spring of the present invention provides a non-linear response to loading.

fOOlO j In this regard, in a further embodiment of the present invention, a mattress is provided that includes a plurality of the exemplar springs of the present invention. In the mattress, the springs are arranged in a matrix, such that the upper end convolutions of the coiled wires form a first support surface and the lower end convolutions of the coiled wires form 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 sidewal! extends between the upper body supporting layer and the lower foundation layer, and around the entire periphery of the two layers, such that the spring are completely surrounded.

[0011] 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-limitin examples in this document. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG, 1 is a perspective view of an exemplary spring made in accordance with the present, invention;

[0013] FIG, 2 A is a side view of the exemplary spring of FIG . i;

[0014] FIG. 2B is another side view of the exemplary spring of FIG. 1 , but showing a first force Fi applied to the spring and the spring compressed a first predeiermined compression distance, Di

j0015| FIG. 2C is another side view of the exemplary spring of FIG. 1 , but showing a second force \ applied to the spring and the spring compressed a second predetermined compression distance, t¾;

(0016] FIG. 3 is graph depicting the forces necessary to maintain compression distances of the exemplary spring of FIG. 1 ; and

[0017] FIG, 4 is a perspecti ve view of an exemplary mattress made in accordance wi th the present, invention, with a portion removed to show the plurality of springs in the interior of the mattress.

DESCRIPTION OF EXEM PLARY EMBODIMENTS

(0018] 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 including a coiled wire with one or more spring stops and used within a mattress to provide a user positioned on the mattress increased support, for portions of the user ^' s body when a higher load is applied to the mattress. Thus, the mattress of the present invention provides a user the non-iinear support typicall seen in a foam mattress, but through the use of springs.

[0019] Referring to FIG. I, in one exemplars' embodiment of the present invention, a spring 10 is provided that includes a coiled wire 20 having an upper end convolution 22, a lower end convolution 24 opposite the upper end convolution 22, and five intermediate convolutions 26a~e which helically spiral between the upper end convolution 22 and the lower end convolution 24, and which are each made up of a portion of the coiled wire 20 stibstaniially equal to about one tun ¹ ! of the coiled wire 20 (i.e., about 360° of the helical path of the coiled wire 20 such that, when the spring 10 is placed upright, the beginning portion of each of the intermediate convolutions 26a-e is positioned below and is in vertical alignment, with the ending portion of each of the intermediate convolutions 26a-e.

[0020} Unlike the intermediate convolutions 26a-e, the upper end convolution 22 of the coiled wire 20 ends in a circular loop at the topmost portion of the coiled wire 20, and the lower end convolution 24 similarly forms a circular loop at the lowermost portion of the coiled wire 20. In this way. the upper end convolution 22 and the lower end convolution .24 each terminate in a generally planar form, which serve as the supporting end structures of the spring 10. and which, when combined with the live intermediate convolutions 26a-e, form a coiled wire 20 that is made of a total of seven convolutions or turns. In this regard, the exemplary spring 10 typically has a size similar to that of a typical wire coil spring and includes a height of about 9.8 inches (about 250 mm) to about 15.8 inches (about 400 mm) and a diameter of about 2 inches (about 50 mm) to about 3.2 inches (about 80 mm). Of course, it is also contemplated that various other dimensionally-sized springs, having, for example, different numbers of convolutions or alternate heights and/or diameters could also be produced without departing from the spirit and scope of the present invention.

|0021 | Referring still to FIG. 1 , the exemplar) ¹ spring it) further includes six spring stops 30a _} 30b, 32a. 32b, 34a, 34b that are separately attached io and positioned at predetermined distances along the coiled wire 20, and that are arranged into three pairs of spring stops. In particular, in the exemplary spring 10 shown in FIG- 1 , the spring 10 is comprised of a first pair of springs stops that includes a first spring stop 30a positioned on the second intermediate convolution 26b of the eoiied wire 20 and a second spring stop 30b thai is also positioned on the second intermediate convolution 26b of the eoiied wire 20, but is diametrically opposed from the first spring stop 30a. In other words, the second spring sto 30b is one half of a convolution (i.e., 180" of the helical path of the coiled wire 20) away from the first spring stop 30a. Similarly, a second pair of spring stops includes a first spring stop 32a and a second spring stop 32b that are diametrically opposed from each other on the third intermediate convolution 26c of the coifed wire 20. A. third pair of spring stops then includes a first spring stop 34a and a second spring stop 34b that are diametrically opposed from each other on the fifth intermediate convolution 26e of the coiled wire 20, In this regard, in the exemplary embodiment shown in FIG, 1 , the first spring stop 30a of the first pair of spring stops, the first spring stop 32 a of the second pair of spring stops, and the first spring sto 34a of the third pair of spring stops are all vertically aligned with one another, while the second spring stop 30b of the first pair of spring stops, the second spring stop 32b of the second pair of spring stops, and the second spring stop 34b of the third pair of spring stops are also vertically aligned with one another, the importance of w hich is described in further detail below.

[0022} With further regard t the spring stops 30a, 30b. 32a, 32b, 34a, 34b, each of the spring stops 30a, 30b, 32a, 32b, 34a, 34b are substantially cylindrical with a portion of the coiled wire 20 extending through a longitudinal axis of each of the spring stops 30a, 30b, 32 a, 32b. 34a, 34b. in this way, each of the exemplary spring stops 30a, 30b, 32a, 32b. 34a, 34b substantiall surrounds a portion of the coiled wire 20 with the radius of each of the spring stops 30a, 30b, 32a, 32b, 34a, 34b extending perpendicularly away from the coiled wire 20 such that a portion of each of the spring stops 30a. 30b, 32a, 32b, 34a, 34b is interposed between the particular convolutions 26b, 26c, 26e upon which the spring stops 30a, 30b, 32a, 32b, 34a, 34b are positioned, and either the immediately adjacent intermediate convolutions 26a-e or the upper end convolution 22, the importance of which is aiso described, in further detai l below, in this regard, it is of course contemplated that even though all. of the sprin stops 30a, 30b, 32a, 32b, 34a, 34b are connected to intermediate convolutions 26b. 26c, 26e of the coiled wire 20 in the exemplary spring .10, spring stops used in accordance with the present invention could aiso be connected to the upper end convolution 22, the lower end convolution 24, to the remaining intermediate convolutions 26a, 26d, and io various combinations thereof.

J0023J With further regard to the spring stops 30a, 30b, 32a, 32b, 34a, 34b, and referring stil l to FIG. I , in the exemplary spring 10, the first spring stops 30a, 32a, 34a of each of the pairs of spring stops are the same size as the corresponding second spring stop 30b, 32b, 34b in each of the pairs. However, between the pairs of spring stops, each of the different pairs of spring stops is a different size, in particular, in the exemplary spring 10, the first spring stop 30a and the second spring stop 30b of the first pair of spring stops each have a first radius, while the first spring stop 32a and a second spring stop 32b of the second pair of spring stops each have a second radius that is the larger in size than the radius of the first spring stop 30a and the second spring stop 30b of the first pair of spring stops. In a similar manner, the first, spring stop 34a and the second spring stop 34b of the third pair of spring stops each have a third radi us thai is smaller in size than both the first spring stop 30a and the second spring stop 30b of the first pair of spring stops as well as the first spring stop 32a and the second spring stop 32b of the second pair of spring stops. Again though, the springs of the present invention are not limited to such an arrangement of pairs and sizes of spring stops, but are instead inclusive of spring stops or pairs of spring stops having various other ixe and arrangements.

(0024] Referring still to FIG, 1 , and as mentioned above, the first pair of spring stops 30a, 30b. the second pair of spring stops 32a, 32b and the third pair of spring stops 34a, 34b are positioned, respectively, on the second intermediate convolution 26b, the third intermediate convolution 26c, and the fifth intermediate convolution 26e of the coiled wire 20 such that a portion of each of the spring stops 30a, 30b, 32a, 32b, 34a, 34b is interposed between the particular convolutions 26b, 26c, 26e upon which the spring stops 30a, 30b, 32a, 32b, 34a, 34b are positioned and either the immediately adjacent intermediate convolutions 26a~e or the upper end convolution 22. By arranging the spring slops 30a, 30b. 32a, 32b, 34a, 34b in such a manner, the spring stops 30a. 30b, 32a, 32b, 34a, 34b are thus configured such that when the spring 10 is compressed a predetermined compression distance, the intermediate convolutions 26a-e of the coiled wire 20 compress somewhat before engaging the spring stops 30a, 30b, 32a, 32b, 34a, 34b. At that point, the spring stops 30a, 30b, 32a, 32b, 34a, 34b then maintain a minimum distance or spacing between the respective intermediate convolutions 26b, 26c, 26e upon which the spring stops 30a, 30b, 32a, 32b, 34a, 34b are positioned and the immediately adjacent intermediate convolutions 26a-e or the uppe end convolution 22.

(0025) In the exemplary embodiment shown in FIG; I where the spring stops 30a, 30b, 32a, 32b, 34a, 34b are cylindrical, the minimum distance or spacing is .therefore based, in part, on the radiu of the spring stops 30a. 30b, 32a, 32b. 34a, 34b, but is also based, at least to a certain degree, on the composition of each of the spring stops 30a, 30b, 32a, 32b, 34a, 34b. For example, in the exemplary embodiment shown in FIG. 1 , each of the spring stops 30a, 30b, 32a, 32 b, 34a, 34b are comprised of an elastomer, for example a rubber, which, is sufficiently resilient to maintain the minimum distance and spacing throughout the life of the spring 10, but is also capable of being compressed a. minimum amount as well. Of course, similar to the size and arrangement of the spring stops of the present invention, the materials used to produce the spring stops can also be modified to produce a spring stop having a desired property without departing from the spirit or scope of the present invention,

[0026] Referring now to FIGS. 2 A, 2B, 2C and 3, in operation, the coiled wire 20 functions substantially like a typical helical spring, where the effective spring constant is inversely proportional to the number of convolutions, or fractions thereof, still active in the helical spring. For example, if one half of a helical spring is incapable of compression, the effective spring constant of the spring would be determined based only on the half of the spring still capable of compression (i.e., the active portion of the spring), in other words, when the exemplary spring 10 is uncompressed, as shown in FIG. 2 A, the effective spring constant. j _f of ihe spring 10 is based on all of the i ntermediate convolution s 26a-f of the coiled wire 20.

[0027] Accordingly, when a first predetermined force, Fi, is applied along a longitudinal axis A of the spring 10, all of the intermediate convolutions 26a-f begin to compress simultaneously, and the spring 10 compresses at a constant spring rate according to the initial spring constant. i, until the spring 10 has compressed a first predetermined compression distance, Dj , as shown in FIG. 2B, Then, once the spring 10 has compressed the first predetermined compression distance, D] , the Frrst pair of spring stops 30a, 30b positioned on the second intermediate convolution 26b engage the second pair of spring stops 32a, 32b positioned on the third intermediate convolution 26c. In this way, the first pair of spring stops 30a, 30b and the second pairs of spring stops 32a, 32b together maintain a minimum distance or spacing (i.e., a distance or spacing thai is equal to the size of the first radius of the spring stops 30a, 30b in the first pair of spring stops plus the size of the second radius of the spring slops 32a, 32b in th second pair of spring stops) between the second intermediate convolution 26b and the third intermediate convolution 26c of the coiled wire 20. The springs stops 30a, 30b, 32a, 32b thereby prevent the section of the coiled wire 20 begi nning at the fi rst spring stop 30a of the first pair of spring stops and ending at the second spring stop 32b of the second pair of spring stops from compressing any further (i.e., the section is inactive). At that point, and as also shown in FIG. 2B. only the remaining active portions of the coiled wire 20 (i.e., portions on either side of the inactive section of the coiled wire 20) are capable of compressing further,

[0028] If (he spring 10 is then compressed past the first predetermined compression distance, DK the spring 10 will subsequently compress according to a second effective spring constant, Kj, of the spring 10. The second spring constant, R?, is based on the remaining active portions of the coiled w ire 20 that are sti ll capable of compressing (i.e., the portions of the coiled wire 20 that, are on either side of the inactive section of the coiled wire 20 described above). In particular, when second predetermined (and greater) force, F2, is applied along the longitudinal axis A of the spring 10, the remaining active portions of the coiled wire 20 compress simultaneously, and the spring 10 will compress at a constant, spring rate according to the second spring constant, 2, until the spring 10 has compressed a second predetermined compression distance, D>, as shown in FIG. 2C. Once the spring 10 has been compressed the second predetermined compression distance, Di, the third pair of spring stops 34a, 34b engage the portion of adjacent convolutions of the coiled wire 20 that are vertical ly aligned with the third pair of spring stops 34a, 34b.

Specifically, the first spring stop 34a of the third pair of spring stops engages the upper end convolution 22 of the coiled wire 20 and the second spring stop 34b of the third pair of spring stops engages the fourth intermediate convolution 26d in addition to the upper end convolution 22 of the coiled wire 20. In this way, the third pair of spring stops 34a, 34b maintai n a minimum distance or spacing between the fifth intermediate convolution 26e and the adjacent

convolutions. At that point, and as shown in FIG. 2C, the fifth intermediate convolution 26e also becomes inactive. Then, for any compression distances past the second .predetermined

compression distance,∑ ⁾ · . the spring 10 will compress according to a third effective spring constant, ¾, of the spring 10, which is based on the combination of the spring constants of the remaining active portions of the coiled wire 20 that are still capable of compressing. As more force is applied along the longitudinal axis A of the spring 10 in excess of the second

predetermined force, F2, the remaining active portions of the coiled wire 20 will then

simultaneously compress and additional portions of the coiled wire 20 will become inactive as other intermediate convolutions engage the spring stops (e.g., the fourth intermediate

convolution 26d will eventually engage the first spring stop 34a of the third pai of spring stops) until the spring 10 reaches a maximum compression distance of the spring 10 where the entire length of coiled wire 20 is inactive.

[0029] Referring now more specific-ally to FIG. 3. which graphically depicts the forces necessary to maintain compression distances of the spring 10, the effective spring constant of the spring 10 is the slope of the line at -any given compression distance. Accordingly, as the force applied to the spring 50 increases and the compression distance of the spring 10 increases, more sections of the coiled wire 20 are rendered inactive. As the effective spring constant of the spring 10 is inversely proportional to the number of active coils, or fractions thereof decreasin the amount of active portions of the coiled wire 20 (e.g., at compression distance D i ) increases the effective spring constant of the spring 1 » As the spring constant increases (e.g., from Ki to K ), the spring rate also increases, and the spring 10 becomes "ha de .** Thus, the spring 10 of the present invention provides a non-linear response to loading that can readily he tailored, as desired, by making use of spring stops of dif ferent sizes and arrangements to yield a preferred compression response .

f OI O] Referring now to FIG. 4, i another embodiment of the present inventi on, a mattress 100 is provided that includes a plurality of the springs 10 described with reference to FIGS, 1 , 2A, 2B, 2C, and 3. The springs 10 are arranged i a matrix, such that the upper end convolutions 22 of the coiled wires 20 define a first, support surface, and the lower end convolutions of the coiled wires 20 define a second support surface opposite the first support surface. The mattress 100 also comprises an upper body supporting layer 150 positioned adjacent to the first support surface, along with a lower foundation layer 160 positioned adjacent to the second support surface. Furthermore, a sidew ll 170 extends between the upper body supporting layer 1 50 and the lower foundation layer 16 aromid the entire periphery of the two layers 150, 160, such that the springs 10 are completely surrounded.

{0031 ] li is contemplated that the upper body supporting layer 150 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 150 may be comprised of multiple layers of material configured to improve the comfort or support of the upper bod supporting layer 150.

[0CB2] It is also contemplated that the lower foundation layer 1 0 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 160 is comprised of a rigid member configured to support the plurality of springs 10. (0033) One of ordinary skill in the art will recognize thai addi tional embodiments are also possible without depaititig 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 gi ven 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.