GB2057257A

GB2057257A - Seats

Info

Publication number: GB2057257A
Application number: GB7930378A
Authority: GB
Original assignee: Turner Willenhall Ltd H R
Current assignee: Turner Willenhall Ltd H R
Priority date: 1979-09-01
Filing date: 1979-09-01
Publication date: 1981-04-01
Also published as: GB2057257B

Abstract

A vehicle seat includes a variable stiffness zone in the region corresponding to the lumbar region of a seated occupant to reduce discomfort when seated for prolonged periods. The variable stiffness is provided by a laminated springy rod (16) of elongated cross-section which extends transversely of the seat and is angularly adjustable so that its stiffness as experienced by the seat occupant varies with its angular setting. The rod (16) is enclosed within a sleeve (30) of plastics material and cooperates with a plate which bears against the backrest upholstery to transmit the load exerted by the occupant to the rod (16). Such an arrangement has the advantage that the contour of the upholstery remains unaltered by adjustment of the rod (16). <IMAGE>

Description

SPECIFICATION Improvements relating to seats This invention relates to seats and in particularto seat backrests having a user operable facility for adjusting the degree of support afforded by the backrest.

One area in which most people experience discomfort when seated for long periods of time is the lumbar region of the back. A number of seat designs have been proposed, some of which are currently in use, for allowing variations in the support afforded by the seat in the lumbar region ofthe occupant.

These generally entail varying the contour of the back supporting area for example as shown in Patents Nos. 1 199 756, 1 203322 and 1 011 726.

Such arrangements tend to be relatively complex and expensive to manufacture and the deformed part of the backrest tends to encroach upon the actual seating area which is undesirable.

According to one aspect ofthe present invention we provide an upholstered seat in which the stiffness of the support afforded by at least part of the back supporting area of the backrest is variable without altering the contour thereof.

According to a second aspect of the invention we provide a seat backrest incorporating at least one angularly adjustable elongate back-supporting element which extends generally in the plane of the backrest and whose bending stiffness in said plane varies in dependence on the angular setting of the element.

Preferably user actuable means is provided for adjusting and maintaining the or each element in a selected angular position.

To afford supportforthe lumbar region ofthe occupant, the element may be arranged to extend generally horizontally between side members of the backrest frame so as to supportthe backrest upholstery in the lumbar region of the occupant. The stiffness of the upholstery as experienced by the occupant can then be varied by adjusting the angular setting of said element about its longitudinal axis.

The or each back supporting element conveniently comprises an elongate springy member which is bendable transversely of its axis but is so shaped that, for a transverse load applied in a given direction, the degree of transverse deflection varies according to the angular setting of the element.

In one embodiment, the element may be a flexibly deformable plastics or metal rod of rectangular or other elongated cross-section. It will be understood that the resistance to bending offered by such a rod will be greater for transverse loads applied along the major axis of its cross-section than for transverse loads applied in the direction of its minor axis.

In the preferred embodiment, the back supporting element is of longitudinally laminated construction.

Such a construction enables the desired stiffness characteristics to be realised more easily than with a solid construction. Thus, where for example the element is of rectangular cross-section, instead of being of solid construction it may be constituted by a number of strip laminae. The back supporting element is conveniently enclosed within a sleeve or sleeves of circular section.

To transfer the load applied to the upholstery to the back supporting element, the latter conveniently carries or bears against an intermediate member such as a plate having extending surface contact with the upholstery, the arrangement being such that the element is free to rotate relative to the intermediate member thereby allowing stiffness adjustments to be made by rotating the element without altering the angular orientation of the intermediate member.

Although the back supporting element (when unstressed) can be oflinearconfiguration, other longitudinal shapes are possibie; for example the elements may be preformed with a longitudinal bowed or even sinuous shape. Such shapes may be advantageous in achieving the desired stiffness characteristics; however in the presently preferred embodiment, a linear back supporting element has been found to be satisfactory.

One example ofthe invention is illustrated in the accompanying drawings to which reference will now be made.

In the drawings: Fig. 1 is a perspective view showing part of the backrest frame incorporating a back supporting element in accordance with the invention; and Figs. 2, 3, and 4 are views showing the back supporting element in different angular positions, and also showing an intermediate plate via which loads on the upholstery are transmitted to the back supporting element.

Referring noe to the drawings, reference 10 indicates opposite sides of a U-shaped squab tube forming the backrest frame, the portions illustrated forming the side members of the backrest and having secured thereto hinge plates 12 by means of which the back rest can be hingedly connected to the seat base through the agency of, for example, a reclining mechanism (not shown). In practice, the backrest frame will be upholstered in a conventional manner.

In accordance with the invention however, the lower end of the backrest is spanned by a rotatable back supporting element which may extend generally parallel to the hinge axis between the backrest and seat base.

In the illustrated embodiment, the back supporting element 14 comprises a pack of strip metal or plastics laminae 16(fivelaminaeareshown in the drawings but the number employed may be variable). The opposite ends of the laminae 16 are connected to rotary portions 18, 20 journalled in the sides of the backrest frame. Thus, the ends 22 may for example be formed with apertures 24 to enable them to be connected to the portion 18 by a threaded fastener (not shown) and their opposite ends 26 may be supported in a socket of the portion 20. Some means is provided to enable the element 14 to be rotated about its longitudinal axis over, for example an angle of 90 /O and releasably locked in any desired position of angular adjustment.The adjustment mechanism may take various forms but it not illustrated in the drawings because it is not, in itself, material to the present invention. To facilitate adjustment, the portion 18 may be rotatably fast with a non-circular part 28 on which a handle can be mounted.

The strip laminae 16 are enclosed within a sleeve 30 which may be of plastics material and a plate 32 is mounted on the sleeve via brackets 34 which allow the strip laminae 16 to rotate relative to the plate 32.

The plate 32 will, in the upholstered back rest, bear against the interior surface of the back supporting area of the upholstery so as to transmit the loading due to the presence of the occupant to the strip laminae 16.

By virtue of its construction, it will be seen that the angular position of the back supporting element 14 will govern the degree of stiffness and hence support experienced by the occupant. Thus, when the supporting element is in the position shown in Fig. 2 the resistance offered will be minimum; when in the position of Fig. 4 the resistance will be maximum; and when in the position of Fig. 3, the resistance offered will be intermediate the minimum and maximum values.

It will be noted that rotation of the back supporting element 14 serves to vary the stiffness or degree of support experienced by the seat occupant without varying the contour of the back supporting area.

Although, in the illustrated embodiment this is achieved by means of an element of laminated construction, it will be apparent that it is not essential for the supporting element to be laminated; it may instead be suitably shaped so that the resistance it offers varies according to its angular position.

Claims

1. An upholstered seat in which the stiffness of the support afforded by at least part of the back supporting area of the backrest is variable without altering the contour thereof.

2. A seat backrest incorporating at least one angularly adjustable elongate back-supporting element which extends generally in the plane of the backrest and whose bending stiffness in said plane varies in dependence on the angular setting of the element.

3. A backrest as claimed in Claim 2 in which user actuable means is provided for adjusting and maintaining the or each element in a selected angular position.

4. A backrest as claimed in Claim 2 or 3 in which the e!ement is arranged to extend generally horizontally between side members ofthe backrest frame so as to support the backrest upholstery in the lumbar region of the occupant.

5. A backrest as claimed in Claim 2,3 or4 in which the or each element comprises an elongate springy member which is bendable transversely of its axis but is so shaped that, for a transverse toad applied in a given direction, the degree of transverse deflection varies according to the angular setting of the element.

6. A backrest as claimed in any one of Claims 2 to 5 in which the or each element comprises a flexibly deformable plastics or metal rod of rectangular or other elongated cross-section.

7. A backrest as claimed in any one Claims 2 to 6 in which the back supporting element is of longitudinally laminated construction.

8. A backrest as claimed in any one of Claims 2 to 7 in which the or each element is enclosed within a sleeve of circular section.

9. A backrest as claimed in any one of Claims 2 to 8 in which, to transfer the load applied to the upholstery to the back supporting element, the latter carries or bears against an intermediate member such as a plate having extended surface contact with the uphostery, the arrangement being such that the element is free to rotate relative to the intermediate member thereby allowing stiffness adjustments to be made by rotating the element without altering the angular orientation of the intermediate member.

10. A backrest as claimed in any one of Claims 2 to 9 in which the element, when unstressed, is of linear configuration.

11. A backrest as claimed in any one of Claims 2 to 9 in which the element is preformed with a bowed or sinuous longitudinal shape.

12. A lumbar adjustment mechanism for a seat backrest, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.