Chair shell

Abstract

A one piece chair shell comprising a seat portion and a backrest portion connected by a vertically corrugated integral connecting section.

Description

BACKGROUND OF THE INVENTION

This invention relates to a chair shell of the kind comprising a one-piece moulding defining a seat portion and a backrest portion. The shell is mounted upon a support structure to make the complete chair.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a chair shell which provides a good seating posture commensurate with comfort.

According to the invention a one piece chair shell comprises a seat portion connected to a backrest portion by at least one integral connecting section which is vertically corrugated.

DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a perspective front view of a chair shell constructed in accordance with the invention;

FIG. 2 is an underneath and rear perspective view of the shell;

FIG. 3 is a cross section on the line 3--3 in FIG. 1;

FIG. 4 is an inverted plan view of the seat shell, and

FIG. 5 is a side elevation view.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The chair shell shown is intended to be mounted upon a supporting structure, to which it is connected by fastenings. In this example the shell has headed spigots 9 moulded into its base. These locate in respective apertures formed in lugs on a tubular metal underframe (not shown). The means whereby the shell is attached to the underframe is described and claimed in British Pat. No. 1,086,071. However, other types of fastening means may be substituted for the spigots shown.

The shell comprises a seat portion 10 and a backrest portion 11 which are shaped and positioned in relation to one another to provide comfort as well as a good seating posture. The seat portion 10 is approximately rectangular, having integrally flanged edges. The front edge has a shallow flange 12 joined to the slightly concave seat surface by a curved zone defining on the top surface, a convex surface 12 along the front of the seat. The flanges 13 at the two sides taper in depth, the narrower end being towards the seat front. These flanges 13 are also outwardly flared and join the seat surface with shallow raised lips which are visible in FIG. 1 at 14. The flanges 13 continue to the rear of the seat portion 10, where they are of maximum depth. These continuations are indicated at 15.

The backrest portion 11 is also generally rectangular, though its front surface is substantially curved inwardly to the center. The upper edge of the backrest portion 11 is provided with a shallow flanged edge 16 similar to that at the front of the seat portion 10. The sides of the backrest portion are also provided with flanges 17 and, in similar manner to the seat portion 10, the flange depth is greater at the bottom of the backrest portion, the side flanges tapering uniformly. These flanges are furthermore continued along the lower edge of the backrest portion at 18, at which position their depth is a maximum. The flanges 17, 18 are also outwardly flared or inclined. The lower edge of the backrest portion 11 is of shallow V shape.

Connecting the seat and the backrest portions is a connecting section 19. This is vertically corrugated as shown in FIGS. 1, 3 and 4. It has generally convex contoured side flanges 20 bounded by a pair of ridges 21, between which is defined a concave recess 22. The side flanges 20 join with the flanges 15 at the rear edge of the seat portion 10 and with the flanges 18 at the lower edge of the backrest portion 11, as can be seen from FIGS. 1, 2 and 5.

The central concave recess 22 extends over most of the length of the connecting section 19 but it merges into the respective surfaces of the seat portion 10 and of the backrest portion 11. The ridges 21 merge with the lips 14 of the seat portion and with the edges of the backrest portion respectively.

The connecting section 19 is moreover, concave as viewed in side elevation and is set back behind the general plane of the surface of the backrest portion 11 of the chair shell. This can be seen in FIG. 5. Furthermore, the connecting section widens from its upper to its lower end, since the side flanges 20 are wider at their junction with the flanges 15 of the seat portion than they are at the corresponding junctions with the flanges 18 of the backrest portion 11.

On the underside of the seat portion 10 there are provided integral webs 23. These join the slightly concave or generally flat portion with the two flange continuations 15 at the rear edge and extend, in this example, in parallel relationship over approximately two thirds of the length of the seat portion. The webs 23 are of the same depth at their rear ends as the flanges 15 which they join but taper to their front ends.

The shell is preferably made from a plastics material having some resilience. It is constructed by a moulding process. One suitable material from which it may be made is polypropylene and another is resin bonded glass fiber. The type of material and its thickness determine the strength and relative resilience of the shell. It is however desirable and is designed to provide great strength with a limited degree of resilience in the connecting section 19.

Claims

Having thus described the invention, what is claimed is:

1. A one piece chair shell comprising a seat portion connected to a backrest portion by at least one connecting section which is vertically corrugated and which is substantially narrower than the seat portion and the backrest portion with the vertical corrugations facilitating support of the substantially narrower connecting section and the remainder of the chair shell.

2. The invention in accordance with claim 1 wherein the connecting section is provided with side flanges and a central recess, the section being concave in side elevation.

3. The invention is accordance with claim 2 wherein the seat and backrest portions are flanged and the flanges merge with the connecting section thereby providing a continuous flange about the circumference of the shell

4. The invention in accordance with claim 1 wherein the shell is of a molded plastics material.