SEATING APPARATUS

Abstract: Seating apparatus comprising a seat support (1) carrying a seat (6), a back element (10) pivoted to said seat support (1) which can articulate between forward and rearward positions in relation thereto, and torsion bar means (14,15) extending between the back element (10) and the seat support (1) which resiliently bias said back element towards the forward position.

Description: This invention relates to seating apparatus which can be in the form of a seat, a chair, sofa or other appliance which is used for seating purposes. It is known to provide seats and chairs with what is sometimes referred to as a swing back, that is, the back, or a portion of which against which the user's back or shoulders rests, can articulate in relation to the seat portion or its support under resilient control. The intention is to provide a more comfortable seating arrangement. It is also known with apparatus of this kind to provide the resiliency in the action by means of a torsion device, for example a compression torsion spring. A typical example of this type of chair is shown in British Patent Specification No. 1 203 783 in which a bulky and unsightly compression spring assembly is used. This construction employs a multiplicity of parts which renders it not only expensive to manufacture but is unreliable. German Patent Specification No. 675 688 shows a number of constructions in which torsion bars are used to provide resilient articulation between either a base and a seat support or between a seat support and a back. In these constructions the ends of the torque bars are rigidly held in the frame members of the part of the seat from which the other part is intended to articulate but in most of the constructions shown this creates difficulties in as much that the articulating part of the member concerned is unsupported. In alternative constructions it is intended that a coaxial pair of torque members are provided, one member being a bar and the other a surrounding tube, which extend right across the frame member of the part concerned, although this can provide spaced apart bearings for the members it is an expensive and complicated construction. In another construction shown coaxial torque bars are used which are provided with surrounding tubes to carry the articulation outwards to points adjacent the frame members. Once again this is a complicated and expensive construction and there is no support at the inner ends of the two torque bars. The present invention is intended to provide a seating apparatus construction utilising coaxial torsion bar means which overcomes the disadvantages set forth above by being not only easy and relatively inexpensive to construct but which will provide a positive location of the members. According to the present invention seating apparatus comprises a seat support carrying a seat, a back element pivoted to said seat support which can articulate between forward and rearward positions in relation thereto, and two co-axial torsion bars located on the pivotal axis of rotation and extending between the back element and the seat support which resiliently bias said back element towards the forward position characterised in that, the two axially adjacent ends of said co-axial torsion bars are secured to the seat support, and the back element is secured to the torsion bars at points adjacent their axially spaced apart ends. The term "torsion bar" is used herein to mean not only a solid bar but also laminated bars, tubes or other elements which can operate in this manner. In a convenient construction the torsion bars are provided with axially spaced apart ends which act as pivots for the back element. This particular construction provides a very simple and neat assembly. The two co-axial torsion bars may be formed by a single member which is secured to the seat support at a mid point. The torsion bar may be made from an aluminium alloy such as a copper bearing alloy of the 7,000 series. The construction set forth above is applicable for use with constructions in which the seat support and the back support are made from a lightweight material, for example aluminium or an aluminium alloy. With this construction the back support and the seat support may be made from tube material, for example square tubing. The invention is particularly although not exclusively applicable therefore for relatively lightweight stackable chairs and thus, the seat support may be shaped to allow the seating appliances to nest one above the other. The invention can be performed in various ways but one embodiment will now be described by way of example and with reference to the accompanying drawings in which : Figure 1 is a side elevation of a stackable chair embodying the invention; Figure 2 is a part-view of the chair shown in Figure 1 with the seat removed to disclose the connection between the back support and the seat support; Figure 3 is an enlarged part-view of the construction shown in Figures 1 and 2; Figure 4 is a part cross-sectional view of the manner of articulating the back support to the seat support looking in the direction of the arrow IV in Figure 2; and, Figure 5 is a part cross-sectional view showing the stop construction. As shown in the drawings the seating apparatus is in the form of a stackable chair which is made from aluminium or aluminium alloy tubing of square cross-section. A seat support, indicated generally by reference numeral 1, comprises a pair of U-shaped legs 2 and 3 which are connected together by a U-shaped bracket 4 which extends between them, the bracket 4 being substantially horizontal and the legs 2 and 3 substantially vertical in the manner shown in Figure 1. The dimensions of the legs 2 and 3 are arranged in known manner so that the chairs can nest one above the other to form a stack. The upper rails 5 of each of the legs 2 and 3 are connected to the bracket 4 by welding and a eat 6 is mounted on the bracket 4 in any convenient manner. An additional box cross-section member 7 also extends between the upper rails 5 and is welded in position between them. A back element indicated generally by reference numeral 10 comprises a further U-shaped frame 11, the lower ends 12 of which curve forward as is most clearly seen in Figure 2. A padded back rest 13 spans the upper part of the U-shaped frame. The lower ends 12 of the back element are engaged by a pair of torsion bars 14 and 15 which are formed from a single member made from a suitable aluminium alloy such as a copper bearing alloy of the 7,000 series. This member has a square centre portion 16, circular cross-section portions each side of it which form the torsion bars 14 and 15, outer square section portions 17 and 18 and portions of circular cross-section 19 and 20 which act as pivots in the manner to be described. The central portion 16 is engaged with a force fit in a square section bore 21 in a mounting block 22 and the square section outer portions 17 and 18 are similarly engaged with a force fit in square bores 23 and 24 in the forward positions 12 of the back element. The mounting block 22 is welded to the cross member 7 as indicated by reference numeral 26. The front face 27 of the mounting block 22 can be chamfered fore and aft to allow a predetermined loading to be applied to the back element in a manner to be described. The pivot ends 19 and 20 of the torsion bar element are located in bearings 28 and 29 carried in suitable bores in the top rails 5 of the seat support members 2 and 3. The seat support is assembled to the back element in the manner shown in Figure 4 and so that the back element can pivot against the resilient effect of the torsion bars 14 and 15 between a forward position as indicated in Figures 1 and 3 and a rearward position as indicated in broken lines by reference numeral 30. The chamfer on the front surface of the mounting block 22 is arranged so that when the block is secured in position it applies a pre-load to the torsion bars 14 and 15 urging the back element into the forward position. When a load is applied backwards against the back element it can move rearwardly against the resilient action of the torsion bars until it reaches a position where the lower surface of the lower ends 12 engage stops 31 secured to the rear legs and which act to limit the backwards movement. Forward motion of the back element is limited by stops 33 in the form of T-section inserts 34 located in slots 35 in the cross member 7. The inserts are placed in position by passing them through enlarged openings 36. The forward surface of each of the lower ends 12 has a stepped abutment 37 which engages the appropriate insert 34 which therefore acts as a forward stop. It will be appreciated that this construction provides a neat and simple appearance as the mechanism for controlling the back element is hidden beneath the seat 6. If desired a suitably sized opening 38 can be provided in one of the upper rails 5 to enable the torsion bar to be inserted through the rail. With this arrangement the bearing 29 would have to be suitably dimensioned to allow a passage of the torsion bar before the bearing is located in place. The opening 38 can be closed by a plug 39 made, for example, from a plastics material. The invention can be applied to seats in many other ways and if necessary the mechanism can be in other parts of the appliance, for example, the seat support can be provided with an upwardly projecting portion so that the pivoted back element rotates about a point vertically higher than the seat 6. It will also be appreciated that the invention, as claimed, can be applied to any form of seating apparatus in which it is desired to have a resiliently movable back element, for example a sofa but in this case it might be necessary to provide a series of co-axial torsion bars to carry the greater loadings.

Claims: Seating apparatus comprising a seat support (1) carrying a seat (6), a back element (10) pivoted to said seat support (1) which can articulate between forward and rearward positions in relation thereto and two co-axial torsion bars (14)(15) located on the pivotal axis of rotation and extending between the back element (10) and the seat support (1) which resiliently bias said back element (10) towards the forward position characterised in that the two axially adjacent ends of said co-axial torsion bars are secured to the seat support (1) and the back element (10) is secured to the torsion bars (14)(15) at points adjacent their axially spaced apart ends. Seating apparatus as claimed in claim 1 characterised in that the torsion bars (14)(15) are provided with axially spaced apart ends (19)(20) which act as pivots for the back element (10). Seating apparatus as claimed in claim 1 or claim 2 characterised in that the two torsion bars (14)(15) are provided by a single member (14)(15) which is secured to the seat support (1) at a mid point. Seating apparatus as claimed in claim 1, claim 2 or claim 3 characterised in that the torsion bars (14)(15) are made from an aluminium alloy. Seating apparatus as claimed in claims 1 to 4 characterised in that the seat support (1) and the back support (10) are made from a light weight material. Seating apparatus as claimed in claim 5 characterised in that the seat support (1) and the back support (10) are made from square tube material. Seating apparatus as claimed in claims 1 to 6 characterised in that the seat support (1) is shaped to allow the seating appliances to nest one above the other.

Inventors: BURGESS, GERALD NUTLAND
Applicants: BURGESS, GERALD NUTLAND
Application year: 1989
Main classification: A47C7
IPC codes: A47C7