초록 ▼

A chair with a flexible resilient back support structure includes a hollow tubular seat frame, a hollow tubular backrest frame pivotally connected to the seat frame, and a limit stop affixed to the backrest frame or the seat frame adjacent to the pivot points. The limit stop is configured to limit a

A chair with a flexible resilient back support structure includes a hollow tubular seat frame, a hollow tubular backrest frame pivotally connected to the seat frame, and a limit stop affixed to the backrest frame or the seat frame adjacent to the pivot points. The limit stop is configured to limit a degree of rotation of the backrest frame between an upright position and a maximum backwardly rotated position. An elongate spring element extends from within the backrest frame into the seat frame, and is configured to bias the backrest frame in the upright position, and to resiliently resist backward rotation. In various embodiments, a cam surface is associated with the spring element, providing an effective fulcrum point which moves rearwardly as the backrest frame reclines, thereby increasing the effective flexural resistance of the spring element during reclining.

대표청구항 ▼

1. A chair, comprising:a) a hollow tubular seat frame, having at least two spaced apart open ends;b) a hollow tubular backrest frame, having a pair of spaced apart open ends aligned with and pivotally connected to the open ends of the seat frame at fixed pivot points;c) a limit stop, affixed to each

1. A chair, comprising:a) a hollow tubular seat frame, having at least two spaced apart open ends;b) a hollow tubular backrest frame, having a pair of spaced apart open ends aligned with and pivotally connected to the open ends of the seat frame at fixed pivot points;c) a limit stop, affixed to each of one of the backrest frame and the seat frame, configured to limit a degree of rotation of the backrest frame relative to the seat frame between an upright position and a maximum backwardly rotated position; andd) a substantially solid elongate spring element, extending from within each open end of the backrest frame into the corresponding open end of the seat frame, configured to bias the backrest frame in the upright position, and to resiliently resist backward rotation of the backrest frame. 2. A chair in accordance with claim 1, wherein the limit stop is disposed within each of one of the backrest frame and the seat frame, and extends into the corresponding open end of the other one of the seat frame and the backrest frame. 3. A chair in accordance with claim 1, wherein the spring element abuts the lower inner surface of the seat frame and an upper inner surface of the backrest frame. 4. A chair in accordance with claim 3, wherein the spring element further comprises a longitudinally curved lower surface producing a fulcrum point of contact of the spring element with the lower inner surface of the seat frame, the curved lower surface causing the effective position of the fulcrum point to move rearwardly as the backrest frame is rotated backwardly, thereby increasing the effective flexural resistance of the spring element during said rotation. 5. A chair in accordance with claim 3, further comprising a wedge disposed between the upper inner surface of the seat frame and the adjacent portion of the spring element, so as to maintain the spring element in contact with the lower inner surface of the seat frame. 6. A chair in accordance with claim 3, further comprising a hold-down assembly, disposed within the seat frame hollow member, and attached to an end of the spring element, configured to hold the spring element toward the lower inner surface of the seat frame. 7. A chair in accordance with claim 6, wherein the hold-down assembly includes an adjustment screw extending through a lower side of the seat frame hollow member, so as to allow adjustment of the biasing force provided by the spring element. 8. A chair in accordance with claim 1, wherein the spring element abuts the upper inner surface of the seat frame and an upper inner surface of the backrest frame. 9. A chair in accordance with claim 8, further comprising a wedge disposed between the lower inner surface of the seat frame and the adjacent portion of the spring element, so as to maintain the spring element in contact with the upper inner surface of the seat frame. 10. A chair in accordance with claim 8, further comprising a downwardly sloping cam surface, disposed adjacent the fixed pivot point and below the spring element, configured to allow downward bending of the spring element during backward rotation of the backrest frame, and to provide a fulcrum point of contact between the cam surface and the spring element, such that the effective location of the fulcrum point moves rearwardly as the backrest frame is rotated backwardly, thereby increasing the effective flexural resistance of the spring element during said rotation. 11. A chair in accordance with claim 1, wherein the spring element is formed of a material selected from the group consisting of metals and polymers. 12. A chair in accordance with claim 11, wherein the polymers include fiber-reinforced composites, rubber, plastic. 13. A chair in accordance with claim 12, wherein the spring element is formed of fiberglass resin. 14. A chair in accordance with claim 1, further comprising an armrest assembly fixedly attached to the backrest frame. 15. A chair in accordance with claim 1, wherein the fixed pivot po ints comprise mechanical hinges having pivotally connected hinge members externally disposed on the seat frame and the backrest frame, and the limit stop comprises a stop member attached to one of the hinge members and configured to pivot from a first position wherein relative rotation of the hinge members is permitted, to a mechanically stopped position wherein relative rotation of the hinge members is prevented. 16. A chair in accordance with claim 15, wherein the stop member comprises an extension of a first one of the hinge members, and wherein the stop member includes a stop surface configured to abut a surface of a second one of the hinge members when in the mechanically stopped position. 17. A chair, comprising:a) a tubular frame, having seat frame and backrest frame portions;b) a hinge, pivotally connecting the seat frame and backrest frame together at a fixed pivot point;c) a limit stop, affixed to one of the seat frame and backrest frame portions, configured to limit a degree of rotation of the backrest frame relative to the seat frame between an upright position and a maximum backwardly rotated position;d) an elongate flexural spring element, biased within the seat frame and the backrest frame adjacent to the pivot point, configured to bias the backrest in the upright position, and to resiliently resist backward rotation of the backrest portion; ande) a cam surface, associated with the spring element, providing an effective fulcrum point of contact with the spring element which moves rearwardly as the backrest frame is rotated backwardly, thereby increasing the effective flexural resistance of the spring element during said rotation. 18. A chair in accordance with claim 17, wherein the limit stop comprises a stop member, affixed to one of the backrest frame and the seat frame, having a stop surface configured to move from a first position wherein relative rotation of the seat frame and backrest frame portions is permitted, to a mechanically stopped position wherein relative rotation of the seat frame and backrest frame portions is prevented configured.