ASYMMETRICAL COMBINED CYLINDRICAL AND CONICAL SPRINGS
A mattress comprising asymmetrical coil springs with spring rates that provide comfort to users with different weights. The lower portion of the spring is cylindrical and the upper portion is conical or frustoconical. This arrangement causes the spring to compress with a first substantially constant spring rate for a substantial part of compression, and with a second substantially constant spring rate for a remaining part of compression. The result is a mattress that is sufficiently soft for lighter users and sufficiently firm for heavier users.
1 . A coil spring for cushion support, comprising:
an upper conical section having a plurality of active convolutions; and
a lower, substantially cylindrical section disposed below the upper section having a plurality of active convolutions;
wherein in response to a load, the coil spring compresses with a first substantially constant spring rate for a substantial part of compression, and with a second substantially constant spring rate for a remaining part of compression; and
wherein the second spring rate is higher than the first spring rate.
2 . The coil spring of claim 1 , wherein the coil spring is formed from metallurgical composition containing one or more selected from the group of steel, chromium, nickel, molybdenum, copper, titanium, cobalt, niobium, vanadium, aluminum, platinum, and tungsten.
3 . The coil spring of claim 1 , wherein the coil spring is formed from multi-stranded wire cable.
4 . The coil spring of claim 1 , wherein the coil spring comprises an encased coil.
5 . The coil spring of claim 1 , wherein the coil spring comprises an open coil.
6 . The coil spring of claim 1 , wherein a plurality of the coil springs are arranged in rows and columns such that each coil spring is adjacent to at least one other coil spring.
7 . The coil spring of claim 6 , wherein adjacent coil springs are connected with adhesive.
8 . The coil spring of claim 6 , wherein adjacent coil springs are connected with at least one of a hog ring and other metal fasteners.
9 . The coil spring of claim 6 , wherein adjacent coil springs are not connected along the upper section of the coils.
10 . The coil spring of claim 1 , wherein the coil spring is adapted for a cushioned support structure such as a mattress.
11 . The coil spring of claim 1 , wherein the coil spring is composed of wire having a diameter of about 0.074″ to about 0.088″.
12 . The coil spring of claim 1 , wherein diameter of an active convolution at the top end of the upper conical section varies from about 1.25″ to about 1.75″.
13 . The coil spring of claim 1 , wherein diameter of a largest active convolution of the coil spring varies from about 2.25″ to about 2.75″.