Ergonomic seat and back structure for a chair

Claim 2

A chair construction, including: a flexible, resilient inner shell formed of a plastic and having a seat portion with side edges, a pair of supports formed separately from said inner shell and located below said seat portion of said inner shell, each of said supports engaging and supporting said seat portion along a side edge of said seat portion, means attaching said seat portion of said inner shell to said supports to limit upwardly, laterally, rearwardly and forwardly movement of said seat portion of said inner shell relative to said supports when no weight is applied to said seat portion while not interfering with the downwardly flexing of said seat portion relative to said supports when weight is applied to said seat portion, said means including loops extending from said seat portion and mounted for limited downward movement relative to said supports as the seat portion flexes downwardly when weight is applied thereto.

Claim 3

The chair construction of claim 1 in which said means attaching said seat portion of said inner shell to said supports includes: a pair of upwardly opening loops extending downwardly from said seat portion of said inner shell inwardly of said side edges of said seat portion, each loop positioned along side one of said supports and having a bight portion at its lower end, fasteners extending through said loops above said bight portions to engage said bight portions to prevent upwardly movement of said seat portion when no weight is applied to said seat portion while permitting limited downward movement of said loops when weight is applied to said seat portion, and hooks formed as part of said seat portion with said hooks extending downwardly from said seat portion into slots formed in said supports with said hooks engaging said supports inside said slots around edges of said slots to prevent upwardly movement of said seat portion when no weight is applied to said seat portion, said hooks being located rearwardly of said loops.

Claim 4

The chair construction of claim 1 in which said curved portion of each of said supports is formed as an inverted channel.

Claim 5

The chair construction of claim 1 in which said curved surfaces of said supports slope toward the inside of said seat portion.

Claim 6

The chair construction of claim 1 in which said means attaching said seat portion of said inner shell to said supports attach to said supports below said seat portion.

Claim 7

A seat and back construction for an office chair, including: a U-shaped stretcher tube adapted to be supported on a chair post, a pair of brackets attached to the opposite ends of the U-shaped stretcher tube, an inner shell formed of a flexible, resilient plastic and having a seat portion and a back portion, said seat portion of said inner shell supported on said pair of brackets for flexing movement of the center of said seat portion relative to said brackets, an outer shell formed of a plastic with said outer shell being more rigid than said inner shell, and means connecting said outer shell to said brackets and to said back portion of said inner shell to transfer loads applied to said back portion of said inner shell to said brackets.

Claim 8

A seat and back construction for an office chair, including: a U-shaped stretcher tube adapted to be supported on a chair post, a pair of brackets attached to the opposite ends of the U-shaped stretcher tube, an inner shell formed of a flexible, resilient plastic and having a seat portion and a back portion, said seat portion of said inner shell supported on said pair of brackets for flexing movement of the center of said seat portion relative to said brackets, an outer shell formed of a plastic with said outer shell being more rigid than said inner shell, and means connecting said outer shell to said brackets and to said back portion of said inner shell to transfer loads applied to said back portion of said inner shell to said brackets.

Claim 9

The seat and back construction of claim 6 in which said means connecting said outer shell to said brackets includes flats formed on said outer shell to engage said brackets and fasteners extending through said flats and into said brackets.

Claim 10

The seat and back construction of claim 6 in which said means connecting said outer shell to said back portion of said inner shell includes brackets formed on opposite sides of said outer shell, bosses formed on said back portion of said inner shell and fasteners extending through said brackets and into said bosses.