Three-stage concentric coil spring system
View Patent ↗A spring system that includes at least an inner spring and an outer spring disposed around the inner spring. The inner spring exhibits a stiffness (k 1 ) and the outer spring exhibits a stiffness (k 2 ) in an uncompressed state. The inner spring exhibits a stiffness (k 3 ) and the outer spring exhibits the stiffness (k 2 ) in an intermediate compressed state, and the inner spring exhibits the stiffness (k 3 ) and the outer spring exhibits a stiffness (k 4 ) in a fully compressed state. In this manner, the spring system of the present disclosure may provide a vehicle with variable rates of compression that assist in providing a smooth ride at lower loads or jounce levels.
1. A spring suspension system for a vehicle comprising a first coil spring concentrically disposed within a second coil spring, each of the first and second coil springs including a first zone unitary with a second zone, the first zone having a different stiffness than the second zone such that during compression of the first and second coil springs, the spring suspension system will exhibit a first stiffness, a second stiffness, and a third stiffness,
wherein the different stiffnesses of the first zone and the second zone are provided by differing a coil thickness in each of the first zone and the second zone.
2. The spring system of claim 1 , wherein the stiffness of the first coil spring is less than the stiffness of the second coil spring.
3. The spring system of claim 1 , wherein the first stiffness is less than the second stiffness, and the second stiffness is less than the third stiffness.
4. The spring system of claim 1 , wherein the first coil spring exhibits a stiffness (k 1 ) and the second coil spring exhibits a stiffness (k 2 ) in an uncompressed state, the first coil spring exhibits a stiffness (k 3 ) and the second coil spring exhibits the stiffness (k 2 ) in an intermediate compressed state, and the first coil spring exhibits the stiffness (k 3 ) and the second coil spring exhibits a stiffness (k 4 ) in a fully compressed state.
5. The spring system of claim 4 , wherein (k 1 )+(k 2 )=(kA), (k 2 )+(k 3 )=(kB), (k 3 )+(k 4 )=(kC), and (kA)<(kB)<(kC); and
(kA), (kB), and (kC) are spring constants for the spring system in each of a non-compressed, an intermediate-compressed, and a full-compressed state, respectively.
6. The spring system of claim 4 , wherein a difference in stiffness between (k 1 ) and (k 3 ) and a difference in stiffness between (k 2 ) and (k 4 ) is provided by each of the first and second coil springs having the first zone and the second zone that each exhibit the different stiffnesses.