Coil springs with non-linear loading responses and mattresses including the same
A spring is provided that exhibits a variable and non-linear loading response upon compression. The spring comprises a continuous wire having a lower end convolution, an upper end convolution, and a plurality of helical intermediate convolutions. The upper end convolution, the lower end convolution, and the helical intermediate convolutions each have a respective diameter, with the continuous wire further defining a pitch between the various convolutions. In the spring, one or more of the diameters of the convolutions or one or more of the pitches varies along the length of the continuous wire such that the spring exhibits a non-linear loading response upon compression. A mattress is further provided and includes a plurality of the springs arranged in a matrix.
1. A coil spring, comprising:
a continuous wire having a length and forming an upper end convolution, a lower end convolution opposite the upper end convolution, and a plurality of helical intermediate convolutions between the upper end convolution and the lower end convolution,
the upper end convolution having a diameter, the lower end convolution having a diameter, and each of the plurality of helical intermediate convolutions having a respective diameter, and
the continuous wire defining a pitch between each one of the plurality of helical intermediate convolutions, a pitch between the upper end convolution and the helical intermediate convolution adjacent the upper end convolution, and a pitch between the lower end convolution and the helical intermediate convolution adjacent the lower end convolution,
wherein at least one of the pitches is different than another one of the pitches or at least one of the diameters is different from another one of the diameters such that the coil spring exhibits a non-linear loading response upon compression;
wherein the plurality of helical intermediate convolutions comprises a first portion of helical intermediate convolutions having a first diameter and a second portion of helical intermediate convolutions having a second diameter;
wherein the second diameter is less than the first diameter;
wherein the first portion of helical intermediate convolutions comprises a first helical intermediate convolution, a third helical intermediate convolution, and a fifth helical intermediate convolution of the continuous wire, and wherein the second portion of helical intermediate convolutions comprises a second helical intermediate convolution and a fourth helical intermediate convolution of the continuous wire.
2. The coil spring of claim 1 , wherein the continuous wire includes a lower portion comprised of the lower end convolution and one or more of the helical intermediate convolutions, and an upper portion comprised of the upper end convolution and one or more of the helical intermediate convolutions.
3. The coil spring of claim 2 , wherein each of the pitches in the lower portion is greater than each of the pitches in the upper portion.
4. The coil spring of claim 2 , wherein the diameters of the one or more helical intermediate convolutions in the upper portion are equal to the diameters of the one or more helical intermediate convolutions in the lower portion and to the diameter of the lower end convolution, and
wherein the diameter of the upper end convolution is less than each diameter of the one or more helical intermediate convolutions in the upper portion.
5. The coil spring of claim 2 , wherein the one or more helical intermediate convolutions in the lower portion comprise a first helical intermediate convolution, a second helical intermediate convolution, and a third helical intermediate convolution of the continuous wire, and
wherein the one or more helical intermediate convolutions in the upper portion comprise a fourth helical intermediate convolution and a fifth helical intermediate convolution of the continuous wire.
6. The coil spring of claim 5 , wherein the diameters of the lower end convolution, the first helical intermediate convolution, the second helical intermediate convolution, the third helical intermediate convolution, the fourth helical intermediate convolution, and the fifth helical intermediate convolution are substantially equal to one another, and
wherein the pitch between the lower end convolution and the first helical intermediate convolution, the pitch between the first helical intermediate convolution and the second helical intermediate convolution, and the pitch between the second helical intermediate convolution and the third helical intermediate convolution are each greater than the pitch between the third helical intermediate convolution and the fourth helical intermediate convolution, the pitch between the fourth helical intermediate convolution and the fifth helical intermediate convolution, and the pitch between the fifth helical intermediate convolution and the upper end convolution.
7. The coil spring of claim 1 , wherein the diameter of the lower end convolution and the diameter of the upper end convolution are both equal to the second diameter.
8. The coil spring of claim 1 , wherein the pitch between the lower end convolution and the first helical intermediate convolution, the pitch between the first helical intermediate convolution and the second helical intermediate convolution, the pitch between the third helical intermediate convolution and the fourth helical intermediate convolution, the pitch between the fourth helical intermediate convolution and the fifth helical intermediate convolution, and the pitch between the fifth helical intermediate convolution and the upper end convolution are substantially equal.
9. The coil spring of claim 1 , wherein the continuous wire includes a lower portion comprised of the lower end convolution and one or more of the helical intermediate convolutions, a central portion comprised of at least two helical intermediate convolutions, and an upper portion comprised of the upper end convolution and one or more of the helical intermediate convolutions.
10. The coil spring of claim 9 , wherein the diameters of the lower end convolution and the one or more of the helical intermediate convolutions of the lower portion, the diameters of the at least two helical intermediate convolutions of the central portion, and the diameters of the upper end convolution and the one or more of the helical intermediate convolutions of the upper portion are substantially equal.
11. The coil spring of claim 9 , wherein the pitch between the at least two helical intermediate convolutions of the central portion is less than each of the pitches in the lower portion and the upper portion of the continuous wire.
12. The coil spring of claim 11 , wherein the lower portion comprises a first helical intermediate convolution of the continuous wire, the central portion comprises a second helical intermediate convolution and a third helical intermediate convolution of the continuous wire, and the upper portion comprises a fourth helical intermediate convolution and a fifth helical intermediate convolution of the continuous wire.
13. The coil spring of claim 12 , wherein the pitch between the lower end convolution and the first helical intermediate convolution, the pitch between the first helical intermediate convolution and the second helical intermediate convolution, the pitch between the fourth helical intermediate convolution and the fifth helical intermediate convolution, and the pitch between the fifth helical intermediate convolution and the upper end convolution are substantially equal.
14. The coil spring of claim 1 , further comprising a fabric pocket enclosing the continuous wire.