GB2335845A

GB2335845A - Seat assembly providing adjustable lumbar support

Info

Publication number: GB2335845A
Application number: GB9806637A
Authority: GB
Inventors: Bryan Mitchell
Original assignee: Youngflex AG
Current assignee: L&P Swiss Holding GmbH
Priority date: 1998-03-27
Filing date: 1998-03-27
Publication date: 1999-10-06
Anticipated expiration: 2018-03-27
Also published as: GB9806637D0; GB2335845B

Abstract

A seat assembly providing adjustable lumbar support comprises a resiliently extensible transverse belt (4) the ends of which are linked to lever elements (3) that are fixed to rotatable adjusting pulleys (5). One of the pulleys (5) is directly linked to an adjusting mechanism (7) and the two pulleys (5) are linked together by means of a cable (6) in such a manner that rotation of the one pulley (5) in one direction, causes rotation of the other pulley (5) in the opposite direction. The transverse belt (4) is supplemented by conventional means, not shown, for supporting upholstery that is arranged over the seat frame (1, fig. 1) in conventional manner. Adjustable tensioning of the belt (4) enables the degree of support provided to the upholstery of the seat to be adjusted in the lumbar region.

Description

2335845 1 SEAT ASSEMBLY PROVIDING ADJUSTABLE LUMBAR SUPPORT This invention

concerns a seat assembly of the kind providing adjustable lumbar support, and a suspension element for use therein.

Recently, increased demand for versatile means of adjustment of seating by an occupant, more especially in the field of motor vehicle seating, has led to many attempts to provide improved lumbar adjustment in the backrest of a seat.

Such adjustment is conventionally provided by means enabling the upholstery of the seat to be moved forwardly or rearwardly in the lumbar region of a backrest, in order that the vertical profile of the backrest can be adjusted to suit the spinal curvature of the occupant of the seat.

In the construction of motor vehicle seats, it is conventional to provide a supporting platform, that -is suspended from the seat frame and underlies the seat upholstery and associated cushioning material, usually a pad of foamed plastic.

Hitherto, known lumbar adjustment mechanisms either provide for variation of the vertical profile of such a supporting platform, or provide a discrete lumbar supporting element that is of limited vertical dimension and can thus be moved forwardly and rearwardly independently of other upholstery supports. One such known lumbar supporting element is in the form of a transverse strap or belt the ends of which can be tensioned outwardly to give increased support in the lumbar region and thus vary the effective vertical profile of a seat back when placed under load by the occupant of the seat.

It has hitherto been proposed to provide for lumbar adjustment either of a complete supporting element, or of a discrete element such as the abovementioned strap or belt, by providing means for 2 variably tensioning the supporting platform or other element in a transverse direction.

Most hitherto known arrangements of this kind provide for simultaneous and symmetrical tensioning of any lumbar support means between opposite lateral sides of the seat frame. Such an arrangement is, however, relatively complex and expensive, and thus an arrangement has been proposed that enables use of only a single tensioning mechanism provided between the lumbar support and one side of the seat f rame. Such an arrangement suf f ers f rom the disadvantage, however, that tensioning of an element from only one side of the seat is asymmetrical and places limitations upon the form of lumbar support that can be utilised.

In accordance with the invention there is provided a tensioning arrangement for providing symmetrical transverse tensioning of an upholstery support element linked to a seat frame, said arrangement comprising a pair of pivoted levers each mounted for rotation in an opposite side member of the seat frame and having an extremity linked to an upholstery support element, in such a manner that anti -symmetrical rotation of the levers is effective to tension the transverse supporting element, each of which levers carries a pulley fixed with respect to its rotary axis, the respective pulleys being linked by a common flexible transmission element that is wound about said pulleys in such a manner that said levers are linked for anti -symmetrical rotation under the action of a common adjusting mechanism.

Advantageously, the said adjusting mechanism is directly linked to one of the said pulleys, the transmission element serving to transmit movement from one pulley to the other.

The invention is illustrated by way of example accompanying drawings in which:

in the Fig.1 is a rear elevation, in diagrammatic form, of the frame of a seat backrest; and 3 Fig.2 is a plan view taken in section on the line II-II of Fig. 1.

Referring to the drawings, the frame of a vehicle seat backrest is indicated diagrammatically at 1, and carries at opposite sides thereof brackets 2 within which are mounted spindles of lever elements 3 the extremities of which are linked to the ends of a resiliently extensible transverse belt 4. Each lever 3 is integral with a pulley 5, and, as shown in Fig.2, the respective pulleys 5 are linked by a wire cable 6 the ends of which are respectively anchored to the pulleys 5. As can also be seen from Fig.2, the cable 6 is wound around each pulley in the same sense, which has the effect that upon rotation of one of the levers 3 in one direction, motion is transmitted to the other lever in the opposite direction by way of the cable 6, as indicated by the arrows in Fig.2. One of the pulleys 5 is directly linked to a manual adjusting mechanism 7 that may be of known type and linked to a hand wheel 8.

Thus, upon actuation of the hand wheel 8 the two levers 3 can be rotated in the directions of the arrows of Fig. 2, in order to increase the tension applied to the belt 4 for the purpose of varying the lumbar support provided thereby.

It will be appreciated that in addition to the belt 4 supplementary support will be provided in the seat frame 1 for upholstery of the seat, but such additional support is omitted for clarity. If desired, the belt 4 may act directly upon the upholstery of the seat, or may be arranged to apply tension via a supplementary supporting means for the upholstery of the seat such as conventional seat suspension platform.

4

Claims

1. A tensioning arrangement for providing symmetrical transverse tensioning of an upholstery support element linked to a seat frame, said arrangement comprising a pair of pivoted levers each mounted for rotation in an opposite side member of the seat frame and having an extremity linked to an upholstery support element, in such a manner that antisymmetrical rotation of the levers is effective to tension the transverse supporting element, each of which levers carries a pulley fixed with respect of its rotary axis, the respective pulleys being linked by a common flexible transmission element that is wound about said pulleys in such a manner that said levers are linked for anti- symmetrical rotation under the action of a common adjusting mechanism.

2. An arrangement as claimed in Claim 1, wherein the said adjusting mechanism is directly linked to one of the said pulleys, the transmission element serving to transmit movement from one pulley to the other.

3. An arrangement as claimed in Claim 1 or 2, wherein said upholstery support element comprises a resiliently extensible transverse belt.

4. An arrangement according to any one of Claims 1 to 3 wherein said common flexible transmission element comprises a wire cable the ends of which are respectively anchored to the pulleys.

5. An arrangement as claimed in any one of Claims 1 to 4. wherein the said adjusting mechanism comprises a manually actuable hand wheel mounted in the frame of a vehicle seat and coupled to said adjusting mechanism.

6. A tensioning arrangement substantially as described herein with reference to the accompanying drawings.