Chair seat

• US 6,652,030 B2
• Filed: 10/07/2002
• Issued: 11/25/2003
• Est. Priority Date: 09/01/2000
• Status: Expired due to Fees

• Current Assignee: Irwin Seating Company (Irwin Seating Holding Co.)
• Original Assignee: Irwin Seating Company (Irwin Seating Holding Co.)
• Inventors: Conner, John, Russell, Robert, Coffield, Tim, Finney, Steve
• Primary Examiner(s): Cuomo, Peter M.
• Assistant Examiner(s): EDELL, JOSEPH F
• Application Number:
  US10/266,260
• Publication Number:
  US 20030025372A1
• Time in Patent Office: 414 Days
• Field of Search: 297/331, 297/332, 297/333, 163/03, 163/30
• US Class Current: 297/333
• CPC Class Codes: A47C 7/56 Parts or details of tipping-up chairs, e.g. of theatre chairs
• CPC Class Codes: A47C 7/58 Hinges, e.g. for mounting chairs in a curved row hinges for wings in general E05D
• CPC Class Codes: A47C 7/60 Use of locks or ledges for limiting the seat movement coin-freed apparatus for seats or footstools G07F17/08

Abstract

A chair seat that is movable between an upright and a forward position includes a spring mechanism that biases the seat toward the upright position. The spring mechanism includes camming structures that utilize both compressional and torsional forces from the spring to bias the seat toward the upright position. The compression of the spring exerts a positive force that must be overcome before the seat can be moved out of its upright position. The chair seat is constructed from a number of discrete components that are secured together without the use of welding or separate fasteners, such as via snap-fits. The discrete components include positioning tabs, special shapes, and other features that prevent them from being improperly assembled. The components of the chair seat may all be constructed out of suitable durable plastics, such as polypropylene, polyethylene, polycarbonate, and glass filled thermoplastics.

Claims

1. In a chair seat that is rotatable between a seated position and an upright position, a spring assembly comprising:

a static cam attached to said chair seat, said static cam maintaining the same position with respect to said chair seat when said chair seat is rotated from the upright position to the seated position;

a dynamic cam positioned adjacent said static cam, said dynamic cam both rotating and moving linearly with respect to said chair seat when said chair seat is rotated from the upright position to the seated position; and

a spring positioned adjacent said dynamic cam, said spring being increasingly compressed by said dynamic cam as said chair seat is rotated farther from the upright position toward the seated position, said spring also undergoing torsion when said chair seat is rotated from the upright position to the seated position, whereby both the compression and torsion experienced by said spring cause said spring to urge said chair seat away from the seated position.

2. The chair seat spring assembly of claim 1 wherein said chair seat rotates about an axis, said axis passing through said static cam, said dynamic cam, and said spring.

3. The chair seat of claim 2 further including a bearing adapted to be fixedly supported by a chair base, said bearing including a circular surface portion about which said chair seat rotates.

4. The chair seat of claim 3 wherein said bearing is made of plastic.

5. The chair seat of claim 4 wherein said bearing is attached via a snap-fit to a plastic bracket, said bracket fixedly mounted to the chair base.

6. The chair seat of claim 5 wherein said bracket includes a stop surface adapted to stop the rotation of the chair seat in at least one direction.

7. The chair seat of claim 6 wherein said chair seat includes a bucket adapted to support a cushion on which a user may sit, said bucket being made of molded plastic.

8. The chair seat of claim 5 further including a bearing block snap-fittingly secured to said bearing, said bearing block including a circular aperture dimensioned to receive the circular surface portion of said bearing.

9. The chair seat of claim 2 further including a right bearing and a left bearing adapted to be fixedly supported by a chair base, said right and left bearings including circular surface portions about which said chair seat rotates, said right and left bearings being of different lengths.

10. The chair seat spring assembly of claim 1 wherein said spring is positioned such that said spring experiences substantially no torsion when said chair seat is in the upright position.

11. The chair seat spring assembly of claim 10 wherein said dynamic cam compresses said spring when said chair seat is in the upright position.

12. The chair seat spring assembly of claim 1 wherein said static cam and said dynamic cam are both cylindrical cams with a plurality of cam surfaces, said cam surfaces of said dynamic cam in contact with said plurality of cam surfaces of said static cam.

13. The chair seat spring assembly of claim 1 wherein said static and dynamic cams define a rest position for said chair seat between said upright position and said seated position;

said static and dynamic cams causing said spring to exert a linear force on said dynamic cam when said chair seat is in said rest position such that said spring is partially compressed when said chair seat is in the rest position, said spring thereby exerting a force while said chair seat is in said rest position which must be overcome in order to move said chair seat out of said rest position.

14. The chair seat spring assembly of claim 13 wherein one of said static and dynamic cams includes a stop, said stop determining the position of the chair seat when said chair seat is in the rest position.

15. The chair seat spring assembly of claim 1 wherein said static cam is attached to said chair seat without the use of any welding or separate mechanical fasteners.

16. The chair seat spring assembly of claim 15 further including a spring sleeve positioned around said spring, said spring sleeve attached to said static cam without the use of any welding or separate mechanical fasteners.

17. The chair seat spring assembly of claim 16 wherein said spring is held in said chair seat without the use of any welding or separate mechanical fasteners.

18. A method for controlling the movement of a chair seat that is rotatable from a rest position to a forward position comprising:

providing a spring;

providing a cam member;

positioning the spring in chair seat such that the spring undergoes substantially no torsion when said chair seat is in the rest position; and

compressing the spring in the chair seat against the cam member when said spring is in the rest position such that said spring exerts a linear force against said cam member, said cam member adapted to translate said linear force into a rotational force tat must be overcome before the chair seat can be moved out of the rest position, said cam member further adapted to increase said rotational force as the chair seat is moved farther away from the rest position.

19. The method of claim 18 wherein said spring undergoes torsion and further compression when said chair seat is moved out of said rest position, said torsion and further compression causing said spring to exert a biasing force that biases said chair seat toward said rest position.

20. The method of claim 18 further comprising providing first and second camming surfaces on said cam member, said first camming surface used to bias said chair seat toward said rest position from a first direction, said second camming surface used to bias said chair seat toward said rest position from a second direction.

21. In a chair seat that is rotatable between a seated position and an upright position, a spring assembly adapted to urge the chair seat toward a rest position located between said seated position and the upright position, said spring assembly comprising:

a spring;

a cam adapted to exert a linear force against said spring that increases as said chair seat is rotated farther from said rest position, said spring resisting the linear force with a counter-linear force that said cam translates to a first, counter-rotational force; and

a housing in said chair seat for said spring, said housing adapted to exert a rotational force on said spring that increases as the chair seat is rotated farther from the rest position, said spring resisting said rotational force with a second, counter-rotational force, wherein said first and second counter-rotational forces the urge the chair seat toward the rest position.

22. The spring assembly of claim 21 wherein said first and second counter-rotational forces urge the chair seat toward the rest position both when the chair seat is in the upright position and when the chair seat is in the seat position.

23. The spring assembly of claim 22 wherein said linear force compresses said spring.

24. The spring assembly of claim 23 wherein said cam and said housing are made from molded plastic.

25. The spring assembly of claim 22 wherein said spring is coiled around an axis about which the chair seat is rotatable between the seated and upright positions.

26. The spring assembly of claim 25 wherein said cam is substantially cylindrically shaped.

27. The spring assembly of claim 26 wherein said cam is adapted to move linearly in the direction of the axis when the chair seat is rotated out of the rest position.

28. The spring assembly of claim 27 wherein said housing includes a plastic sleeve adapted to be secured to the chair seat without the use of any separate fasteners.