Patent ID: 8214184

Claim:
A computerized method of designing an uncompressed coil spring shape for quasi-static use to match pre-determined non-constant pitch and non-constant radius distributions in order to avoid interference with components adjacent the coil spring and adjacent spring wire of the coil spring at a compressed condition, which method comprises the steps of: a) determining a desired compressed coil spring profile with desired non-constant pitch and radius distributions at a compressed condition; b) choosing an initial uncompressed coil spring profile for FEA (Finite Element Analysis) input model; c) compressing the uncompressed coil spring profile using FEA to obtain a compressed coil spring profile; d) subtracting the difference in pitch and radius distributions between the desired compressed coil spring profile in step a) and the compressed coil spring profile in step c) from the initial uncompressed coil spring profile in step b) to provide an updated uncompressed coil spring profile, with adjusting a free height of the uncompressed coil spring profile to meet a load requirement; e) repeating steps c) and d) after substituting the updated uncompressed coil spring profile for the uncompressed coil spring profile in step c) until a maximum difference in pitch and radius is smaller than a predetermined tolerance, and providing a corresponding compressed coil spring profile; f) comparing a force line position of the compressed coil spring profile produced in step e) with a force line position target; g) repeating steps c) and f) after making an adjustment to the previously uncompressed coil spring profile until the force line position in step f) is within acceptable tolerances; and h) repeating steps c)-g) until the corresponding compressed coil spring profile in step c) is within acceptable tolerances of the desired compressed coil spring profile determined in step a) and the force line position in step f) is within acceptable tolerances, thereby obtaining an uncompressed coil spring shape.