US 5,464,197 A · Torsion spring having an adjustable spring rate

Abstract

A helical torsion spring is provided having an adjustable spring rate. The torsion spring includes a main spring formed from a coil of wire having a first end and a second end. The wire extends away from the first end to form a first arm and away from the second end to form a second arm. The main spring is loaded torsionally by angular displacement of the first arm with respect to the second arm about a central axis passing through a geometric center of the coil. An inside diameter of the coil defines a core. An adjustment spring is oriented within the core. The adjustment spring is formed from adjustment spring wire configured in a manner similar to that of the main spring. The adjustment spring exhibits an exterior diameter not less than the inside diameter of the main spring. The adjustment spring is rotatable to threadably adjust a proportion of the core of the main spring that includes the adjustment spring therein.

Claims19

Dependent claims

A torsion spring having an adjustable resistance to torsional loads, comprising in combination:

a main spring having a plurality of courses of wire surrounding a central axis of said main spring, said courses forming a coil of wire extending from a first end to .ang. second end, said main spring including means to resist a torsional load applied thereto,
a means removably attachable to said main spring to variably adjust a resistance of said main spring to the torsional load,
whereby a manner in which said variably adjustable resistance means attaches to said main spring controls a spring rating of said main spring, and wherein said variably adjustable resistance means includes means to inhibit modification of a diameter of said coil.

A method for adjusting a resistance of a torsional spring to torsional loads, including the steps of:

providing a main spring including a coil of wire extending from a first end to a second end, the coil having an inside diameter defining a core of the main spring and an outside diameter defining an outer surface of the main spring,
juxtaposing a means to resist modification of either the inside diameter or the outside diameter adjacent a portion of the coil, such that portions of the coil adjacent the diameter modification resistance means resist modification,
determining what amount of torsional load resistance is desired for the main spring, and
translating the diameter modification resistance means along a common central axis of the coil and the diameter modification resistance means until the desired amount of torsional load resistance is exhibited by the main spring.

1 more element

An apparatus for modifying a spring rate of a torsion spring having N.sub.o total number of turns, comprising in combination:

turn disabling means operatively coupled to said spring so as to selectively vary an effective spring rate of said spring, said effective spring rate being determined by the formula:
##EQU5## where k.sub.e is said effective spring rate for said spring,
d is a diameter of wire forming said spring,
E is a modulus of elasticity of a material forming said spring,
C is a constant between 1 and 1,000, and
D is an average unloaded diameter of said spring
N.sub.v is a number of turns of said spring which are disabled by said turn disabling means.

4 more elements

Dependencies are inferred from the claim text.

Torsion spring having an adjustable spring rate

Life of this patent

Torsion spring having an adjustable spring rate

Life of this patent

Abstract

Claims19