Chairs and seats – Bottom or back with means to alter contour – Providing support for lower back region
Patent
1994-05-27
1995-12-12
Cranmer, Laurie K.
Chairs and seats
Bottom or back with means to alter contour
Providing support for lower back region
2972844, A47C 2500
Patent
active
054743583
DESCRIPTION:
BRIEF SUMMARY
This invention concerns improvements in and relating to seat arrangements providing adjustable lumbar support. Such an arrangement is particularly adapted to a seat structure for use in an automobile, bus, minibus, train, office or furniture seat of the kind wherein a platform element providing support for the upholstery of the seat is resiliently suspended in a seat frame.
It is known, see for example EP 0 169 293, that an assembly for incorporation in a seat back to provide adjustable lumbar support may comprise a platform element adapted to be suspended in a seat frame to support the cushioning of a seat rest, said platform element including two elongate lateral rails between which extend transverse members that provide the platform support, adjustable means being linked between respective portions of each of said elongate rails to apply thereto a force of longitudinal compression, whereby said rails are caused to be arched outwardly in the lumbar region of the back rest together with the transverse members carried thereby.
Such an arrangement provides an adjustable and comfortable lumbar support which is of relatively simple design. It has the disadvantage, however, that although the degree of lumbar support can be readily adjusted in the horizontal direction, the vertical position at which lumbar support is provided is determined by the initial geometric shape of the platform element and the points at which the compression forces are applied to the lateral rails, so that it is impossible for an occupant of the seat to adjust the lumbar support in a vertical direction to meet individual requirements.
Other systems are available to provide for vertical adjustment of lumbar support, but these have the disadvantage, either that they are not adaptable to the particular arrangement initially referred to or that adjustment of the vertical and horizontal positions of the lumbar support are not fully independent of one another.
It is accordingly an object of the invention to provide, in a simple manner, a novel construction of seat back that enables both horizontal and vertical adjustment of lumbar support.
The invention accordingly provides a seat back comprising a frame structure from which is resiliently suspended a platform element for supporting upholstery of the seat, said platform element being linked to a first adjusting means for applying a force of longitudinal compression between points of the platform element spaced in a vertical direction, in order to cause resilience buckling of the platform element to arch outwardly in the lumbar region of the back rest, and said platform element being linked to a second adjusting means for effecting vertical displacement of said platform element relatively to the said frame structure.
Advantageously the said second adjusting means is coupled between the frame structure and a lower margin of the said platform element in such a manner that the said lower margin is fixed in its vertically adjusted position. Such an arrangement not only enables the construction of the second adjusting means to be mechanically simple, but also improves the effectiveness of the horizontal lumbar adjustment, since it reduces the tendency of the resiliently suspended platform element to become horizontally displaced to a greater extent by load on the seat back, when the platform element is arched to provide greater lumbar support.
According to one embodiment of the invention, the platform element providing the adjustable lumbar support may be supplemented by a second resiliently suspended platform element located in the upper region of the back rest, the arrangement being such that the further platform element provides support for the upper horizontal margin of the first platform element, whilst accommodating relative sliding motion of the first platform element under the influence of the second adjusting means.
The platform element or platform elements may advantageously be of the kind comprising a wire grid, wherein transverse supporting wires are tensioned between lateral rails that
REFERENCES:
patent: 2756809 (1956-07-01), Endresen
patent: 4632454 (1986-12-01), Naert
patent: 5217278 (1993-06-01), Harrison et al.
Cranmer Laurie K.
Youngflex S.A.
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