Telescoping spring assembly for mattresses and the like
A spring assembly includes telescopically adjustable inner and outer members biased in an extension direction by a coil spring. A non-stretch fabric sleeve fitted about an inner diameter and an outer diameter of the coil spring is closed at its opposite ends to apply a compression preload to the coil spring. The fabric sleeve prevents transmission of the preload to the inner and outer telescoping members, thereby eliminating stickiness and the popping sound that are drawbacks of the prior art, and the fabric sleeve also provides general noise reduction when the spring assembly changes length.
1. A spring assembly, comprising:
a tubular outer member including a support end and an open receiving end opposite the support end;
an inner member including an insertion end and a mounting end opposite the insertion end, wherein the insertion end is received by the outer member through the open receiving end of the outer member;
the outer member being telescopically movable relative to the inner member in a compression direction and an extension direction opposite from the compression direction;
a coil spring arranged to bias the outer member in the extension direction relative to the inner member; and
a fabric sleeve fitted about an inner diameter and an outer diameter of the coil spring, wherein the fabric sleeve is closed at its opposite ends to apply a compression preload to the coil spring.
2. The spring assembly of claim 1 , further comprising a first bumper insert including a rigid housing on which an elastically deformable bumper piece is mounted and a bumper spring, wherein the coil spring has a first end bearing against the first bumper insert, the elastically deformable bumper piece being arranged to face toward the inner member and the bumper spring facing away from the inner member.
3. The spring assembly of claim 2 , further comprising a second bumper insert including a rigid lip, an elastically deformable bumper piece, and a bumper spring, wherein the coil spring has a second end bearing against the second bumper insert, the elastically deformable bumper piece and the bumper spring of the second insert being arranged to face the first bumper insert.
4. The spring assembly of claim 3 , wherein the first bumper insert and the second bumper insert each include airflow passages.
5. The spring assembly of claim 1 , wherein the outer member has an exterior wall and an interior wall, the interior wall including a plurality of axially extending ribs.
6. The spring assembly of claim 5 , wherein the plurality of axially extending ribs are spaced at regular angular intervals about the interior wall of the outer member, adjacent the open receiving end of the outer member.
7. The spring assembly of claim 6 , wherein the inner member includes an external wall and a circumferential shoulder around the external wall; and
wherein the compression preload of the coil spring is such that the axially extending ribs are spaced from engagement with the circumferential shoulder.
8. The spring assembly of claim 7 , wherein the compression preload to the coil spring provides a distance of about one-eighth of an inch between ends of the axially extending ribs and the circumferential shoulder when the spring assembly is at rest and free of external loading.
9. The spring assembly of claim 1 , wherein the mounting end of the inner member includes a fitting for insertion into a corresponding mounting hole of a plate.
10. A method of making a spring assembly, comprising:
providing a tubular outer member including a support end and an open receiving end opposite the support end;
providing an inner member including an insertion end and a mounting end opposite the insertion end;
arranging a coil spring to bias the outer member in the extension direction relative to the inner member, the coil spring having a fabric sleeve fitted about an inner diameter and an outer diameter of the coil spring, wherein the fabric sleeve is closed at its opposite ends to apply a compression preload to the coil spring; and
arranging the insertion end such that it is received by the outer member through the open receiving end of the outer member, the outer member being telescopically movable relative to the inner member in a compression direction and an extension direction opposite from the compression direction.
11. The method of claim 10 , further comprising arranging a first bumper insert bearing against a first end of the coil spring, the first bumper insert including a rigid insert on which an elastically deformable bumper piece is mounted and a bumper spring, the elastically deformable bumper piece being arranged to face toward the inner member and the bumper spring facing away from the inner member.
12. The method of claim 11 , further comprising arranging a second bumper insert bearing against a second end of the coil spring, the second bumper insert including a rigid lip, an elastically deformable bumper piece, and a bumper spring, the rigid lip of the second bumper insert being sized to engage the inner member, the elastically deformable bumper piece and the bumper spring of the second insert being arranged to face the first bumper insert.
13. The method of claim 12 , wherein the first bumper insert and the second bumper insert are provided with air apertures.
14. The method of claim 11 , wherein the compression preload to the coil spring provides a distance of about one-eighth of an inch when the spring assembly is at rest and free of external loading.
15. The method of claim 11 , wherein the outer member has an exterior wall and an interior wall, the interior wall including a plurality of axially extending ribs.
16. The method of claim 15 , wherein the inner member includes a circumferential shoulder around an external wall of the inner member; and
wherein the compression preload of the coil spring is such that the axially extending ribs are spaced from engagement with the circumferential shoulder.