GB2438827A

GB2438827A - Adjustable vehicle seat cushion with movable bolsters

Info

Publication number: GB2438827A
Application number: GB0611272A
Authority: GB
Inventors: Bhavesh Champaneri; Matthew Kitchen; Neal Parkhurst; Steven Martin
Original assignee: Nissan Motor Manufacturing UK Ltd
Current assignee: Nissan Motor Manufacturing UK Ltd
Priority date: 2006-06-08
Filing date: 2006-06-08
Publication date: 2007-12-12
Also published as: GB0611272D0

Abstract

An adjustable seat cushion 3 for a vehicle seat 1 comprises a central support portion 4 and bolsters 5 along opposing side edges of the support portion 4, the cushion 3 further comprising one or more cables 6 extending along the outer side edge of each bolster 5 for co-operating with a tensioning mechanism to tension the cable(s) 6 and to force the bolsters 5 towards the support portion 4. A section of reduced strength (10 Fig 6) may be introduced along the boundary between the support portion 4 and each bolster 5 so that compression of the bolsters 5 takes place in preference to compression of the forward and rear edges of the cushion 3 when the cable 6 is tensioned. A pair of bowden cables may be used to operate the tensioning means (see fig 8).

Description

* 2438827

ADJUSTABLE SEAT CUSHION

This invention relates to a seat cushion and seat for a vehicle, such as a car, a van, a minibus or a bus, and, more particularly, to a seat cushion having adjustable bolsters.

Most vehicle seats are nowadays ergonomically designed to offer improved comfort and support to seated passengers. Indeed, in addition to being able to adjust the seat back angle in relation to the seat base, many vehicle seats are provided with one or more of lumbar supports, head rests, arm rests, thigh supports and side bolsters.

At the lower end of the vehicle market, it may be possible only to adjust the angle of recline of the seat back, with the various lumbar, thigh and side supports being fixed.

Towards the higher end of the market, each of the various supports may be independently adjustable to achieve optimum comfort and support tailored to the individual. Indeed, some vehicle seats may be electronically adjustable and incorporate a memory device for storing and retrieving a particular seat configuration at the touch of a button. However, such fully adjustable seats are expensive, making it uneconomical to incorporate in all vehicles.

It would therefore be desirable to provide a seat for a vehicle incorporating a simple mechanism for adjusting certain of the support elements.

Accordingly, and from a first aspect, the invention resides in an adjustable seat cushion for a vehicle seat, the cushion comprising a central support portion and bolsters along opposing side edges of the support portion, wherein the cushion further comprises at least one cable extending along the outer side edge of each bolster for co-operating with a tensioning mechanism to tension the at least one cable and force the bolsters towards the support portion.

By means of the invention, it is possible for the seat occupant effectively to adjust the seat size by moving the side bolsters towards or away from the central support portion through increasing or decreasing the tension of the cable associated with each bolster.

In this way, for example, a smaller occupant can ensure that he or she is well supported at either side by tensioning the cable in the bolsters using the tensioning mechanism to draw the bolsters towards the support portion.

As well as making it possible to adjust the bolsters' positions to suit the size of occupant, the cable also acts to retain the bolsters in the desired position when the weight of the occupant is placed upon the seat cushion. In this regard, the tensioning mechanism with which the cable co-operates holds the cable at the selected length against the force exerted by the occupant.

From a second aspect, the invention resides in a seat for a vehicle, the seat comprising a seat cushion having a central support portion, bolsters along opposing side edges of the support portion and at least one cable extending along the outer side edge of each bolster, and a tensioning mechanism connected to the at least one cable for tensioning the cable to force the bolsters towards the support portion.

Generally, one end of the cable will be fixed to the seat, such as by means of a bolt secured to a fixing bracket most conveniently located at the rear of the seat, and the other end will be connected to the tensioning mechanism. The tensioning mechanism is preferably mounted on a rigid part of the seat, such as on the seat base, and ideally includes an actuator by means of which the cable tension is controlled. The actuator should be easily accessible, such as by locating it alongside any existing seat rake and height adjustment controls. An example of a tensioning mechanism suitable for use in conjunction with the present invention comprises a cable winding device associated with a winding handle.

Tensioning of the cable to reduce the cable length typically results in translational and/or rotational movement of the bolster towards the support portion, the extent of each type of movement largely depending on the particular composition and shape of the bolsters. Translational movement will generally occur, for example, when the bolster comprises a relatively compressible material and be accompanied by "bulging" of the material away from the region behind the tensioned cable.

Rotational movement will generally occur when the bolster is relatively inflexible, or after an initial degree of compression has occurred. When the cable extends along the outer side edge of the bolster towards the top edge of the seat cushion, and the bolster is compressible, both translation and rotation will typically occur.

For occupant comfort, the majority of side bolsters will have a degree of compressibility and, by careful selection of the bolster filling material and profile design, the desired degree of movement may be achieved. In most instances, the seat cushion will be supported on a substantially rigid seat pan/base or against a substantially rigid seat back, and the bolster will tend to rise upwards (relative to the underlying support) and be drawn inwards towards the central support portion during tensioning.

As will be appreciated, in one embodiment the adjustable seat cushion of the invention may form, or be part of, the seat bottom such that bolsters act as side supports for the thighs, or in another embodiment may form, or be a part of, the seat back, for example to provide side support to the upper torso of the seat occupant.

Equally, both the seat bottom and seat back may include cables for tensioning as herein described.

The profile of the bolsters will usually differ according to whether the bolster is associated with the seat bottom or the seat back, and the profile will also vary along its length. For example, for a seat bottom, the bolster may have a particular profile at a position corresponding to the "hip point" and a different, typically less-rounded, profile forward of the hip point. It will of course be a matter of design to select the particular bolster profile to achieve the optimum level of comfort and support with ease of occupant ingress/egress.

Each bolster may have one or more cables associated with it separate from the cable(s) on the other bolster, thereby making each bolster independently adjustable.

However, for convenience, and to make it easier to achieve a symmetric adjustment of the bolster positions, it is preferred that the or each cable acts on both bolsters. In this way, tensioning of the or each cable causes movement of both bolsters simultaneously. If the bolsters are formed of the same material, and have the same profile, then symmetrical adjustment of the bolsters will generally result.

One means of enabling a single cable to alter the position of both bolsters simultaneously is to extend the cable around the perimeter of the seat cushion, or at least around three sides including both bolster sides.

A preferred arrangement involves securing one end of the cable by a bolt to a fixing bracket at the rear of the seat, and routing the free end of the cable around the perimeter of the seat cushion and back through a guide on the fixing bracket to a tensioning mechanism on the seat. In such an arrangement, the cable effectively extends around the entire cushion periphery.

For improved control over the bolsters' movement, two or more cables running along the bolsters' side edges are preferably provided, each cable being spaced apart from an adjacent cable such that the force applied during tensioning is spread across the side edges.

It is particularly preferred to incorporate twin cables along the bolsters' side edges, each of the cables co-operating with the tensioning mechanism such that they are pulled in opposing directions. By adopting opposing twin cables, it is possible to double the potential lateral movement of each bolster.

Twin cable pullers, such as the PulmaflexTM cable puller utilised in existing seat lumbar support systems, are well suited for this purpose. For example, using the PulmaflexTM system, 180 of handle rotation produces about 30 mm lateral movement of each bolster, so a total of 60 mm lateral movement is possible by running two cables in opposing directions.

It is preferred to route the cable(s) through an outer housing or sheath, for example, in the manner of a Bowden cable. In this way, it is possible to maintain the or each cable in the desired position along the bolsters' side edges and the opportunity for the cable(s) to become dislodged from the side edges is substantially eliminated.

The precise positioning of the cable(s) along the bolsters' side edges will have an effect on the movement of the bolsters during tensioning and, in this regard, running a cable around the top of the bolster side edge will typically result in both translation (direct sideways movement) and rotation of the bolster.

The cable housing or sheath may, for example, run along the inside or the outside of the seat cover. If external, the housing or sheath will usually be selected to match or tone with the seat covering, thereby helping to make the cable run less obtrusive.

A preferred housing or sheath for the cable(s) comprises a webbing material secured to the seat cover, for example by sewing, and through which the cable(s) may be pulled or pushed during assembly. The use of webbing to route the cable is particularly advantageous in that it permits the transfer of the force of the tensioned cable over a larger area. Spreading the force in this way reduces the possibility of localised crushing of the bolster. A webbing material such as of the type used in the manufacture of seatbelts is particularly suitable, having a high degree of flexibility combined with strength.

In a preferred arrangement where the or each cable runs around the perimeter of the seat cushion, tensioning of the cable(s) will result in a compressive force being applied against either or both of the front and rear edges (which in the case of a seat back will comprise the upper and lower edges) of the seat cushion in addition to the bolster side edges. However, this may cause undesirable crushing of the seat cushion along those front and rear edges at the expense of compression of the side bolsters.

Accordingly, it is preferred to introduce a section of reduced strength along the boundaries between the central support portion and each of the side bolsters, such that any force applied by the cables results in compression of the side bolsters in preference to compression of the front and rear cushion edges.

The section of reduced strength along the cushion where the bolsters meet the central support portion may be continuous or intermittent.

For example, in situations where the seat cushion is assembled from individual elements, such as from separate bolsters and central support portion, the bolsters may be attached to the sides of the central support portion at intervals along their length.

Alternatively, the bolsters may be attached to the central support portion along a region that lies below the top of the side edge of the central support portion.

In a preferred arrangement, the seat cushion comprising the central support portion and bolsters will be formed as an integral unit, typically from a foam material and using a foam moulding process. A desired section of reduced strength may then be created by removing some of the foam from the regions that mark the boundary between the support portion and the bolster. This may be achieved by removing an entire length of foam to create a groove along the boundary, with the result that the bolster collapses and/or folds around the groove during tensioning of the cable(s), or by removing shorter lengths or "cut outs" of foam to create an intermittent groove to achieve a similar effect.

Both the depth and width of the groove formed between the central support portion and the bolsters will generally be selected to achieve a preferred bolster profile during the tensioning process. Specifically, the groove profile may not necessarily be uniform along its length. For example, in order to provide greater movement of the bolster towards the rear of the seat (that is, in the region around the hip or lower torso of the occupant), a greater amount of foam will be removed, or a deeper cut will be made, or both, as compared to further along the groove towards the front or upper end of the cushion.

Since it is usual for the seat cushion to be supported on a seat pan or base, which is typically in the form of a pressed sheet of metal having a profile which matches the underside of the cushion, the weight of the occupant will remain supported from beneath despite any weakening of the cushion in the region of the support portion/bolster boundary.

From a third aspect, the invention resides in a vehicle incorporating a seat cushion or a seat according to the first and second aspects of the invention.

In order that the present invention may be more readily understood, reference will now be made, by way of example only, to the accompanying drawings in which: Figure 1 illustrates a vehicle seat in accordance with an embodiment of the present invention indicating the path of the tensioning cable; Figure 2 is a side view of the base of a seat of Figure 1, showing the tensioning cable formed within a length of webbing; Figure 3 is a plan view of the seat cushion illustrating the movement of the sides when placed under tension; Figure 4 illustrates the translational and rotational movement of the seat cushion when tension is applied to the cable; Figure 5 is a lateral vertical cross-section through the cushion foam; Figure 6 is a longitudinal vertical cross-section through the cushion foam; Figure 7 is a plan view of the seat cushion; and Figure 8 illustrates a fixing bracket for the tensioning cables.

Referring to Figures 1 and 2, a vehicle seat 1 comprises a seat back 2 and a seat cushion 3 forming the seat bottom, each of which is made from foam material. The seat cushion 3 comprises a central support portion 4 and two side bolsters 5. The seat cushion 3 is provided with a pair of cables 6 running around the upper half of the outer side of each bolster 5 and the front and back of the central support portion 4 and which are retained within a length of webbing 7 in the manner of a Bowden cable, the webbing 7 being sewn to the seat cover. The cables 6 are tensioned by means of a tensioning system (not shown), such as that marketed under the name Puhnaflex.

The tension is adjusted by rotating a lever 8 on the side of the base of the seat 1. As the tension is increased, the foam material of the seat cushion is compressed, resulting in the bolsters moving inwards so as to reduce the width of the seat cushion and also to change the profile of the upper surface of the seat cushion 3. When the tension is removed, the cushion expands back to its normal size.

Two longitudinal grooves 9 are formed in the upper surface of the seat cushion 3 which separate the central support portion 4 from the two side bolsters 5. In one arrangement, the grooves have a square cross-section of which each dimension is approximately 20 mm. However, in an alternative arrangement, the grooves 9 are deeper towards the rear of the seat cushion 3 than towards the front, so as to provide a greater degree of inward movement of the bolsters 5 towards the rear of the seat cushion 3.

Figure 3 illustrates how the sides of the cushion seat 3 are moved inwards under the influence of the tensioning system. The solid lines indicate the edge of the seat cushion 3 with no tension applied, and the dotted lines indicate the sides of the seat cushion 3 when the seat is under tension. It can be seen from this figure that there is a greater degree of inward movement of the bolsters 5 towards the rear of the seat cushion 3.

As illustrated in Figure 4, the tensioning serves not only to move the bolsters 5 inwards in a translational movement, but also to rotate about the grooves 9. This results from the tensioning cables 6 being positioned in the upper half of the sides of the seat cushion 3.

Figure 5 is a lateral vertical cross-section of the cushion foam taken along the line B-B' in Figure 6, and Figure 6 is a longitudinal vertical cross-section of the cushion foam taken along the line A-A' in Figure 5, illustrating how sections of the foam can be removed from below the grooves 9 of the seat cushion 3 to form columnar voids 10, which serve to reduce the strength of the upper surface of the central support portion 4 of the seat cushion 3 so as to encourage translation of the seat bolsters 5 when the seat cushion 3 is tensioned. A plan view of this arrangement is shown in Figure 7.

Figure 8 illustrates the system for tensioning the cables 6. A first end of each cable 6 is attached to the base of the seat 1 by means of a bolt 11 to a respective fixing bracket 12, and the second end of each cable 6 passes through a respective guide 13 on the fixing bracket 11 and on to tensioning means (not shown).

It will be clear to the skilled person that the present invention may be embodied in other specific forms without departing from its essential attributes. For example, although the seat cushion described above is intended to form a seat bottom, the invention could alternatively, or in addition, be applied to a seat back. Reference should therefore be made to the appended claims rather than the foregoing specific

description as indicating the scope of protection.

Claims

CLAIMS: 1. An adjustable seat cushion for a vehicle seat, the cushion

comprising a central support portion and bolsters along opposing side edges of the support portion, wherein the cushion further comprises at least one cable extending along the outer side edge of each bolster for co-operating with a tensioning mechanism to tension the at least one cable and force the bolsters towards the support portion.

2. A cushion according to claim 1, wherein the at least one cable extends around the periphery of the seat cushion so as to act on both bolsters simultaneously during tensioning.

3. A cushion according to claim 1 or claim 2, comprising two or more cables which extend along the outer side edge of each bolster, each cable being spaced apart from an adjacent cable.

4. A cushion according to any one of claims 1 to 3, comprising two cables for tensioning in opposing directions.

5. A cushion according to any one of the preceding claims, having secured thereto a sheath through which is routed the at least one cable.

6. A cushion according to claim 5, wherein the sheath comprises a webbing.

7. A cushion according to any one of the preceding claims, wherein the cable comprises a Bowden cable.

8. A cushion according to any one of the preceding claims, wherein the at least one cable extends around the side edge of each bolster towards the top edge thereof with respect to the outwardly facing surface of the central support portion.

9. A cushion according to any one of the preceding claims, wherein the boundary between the central support portion and each of the bolsters includes a section of reduced strength along which preferential compression occurs during tensioning of the at least one cable.

10. A cushion according to claim 9, wherein the section of reduced strength comprises a groove.

11. A cushion according to claim 10, wherein the groove is continuous.

12. A cushion according to claim 10 or claim 11, wherein the groove has a non-uniform profile along its length for encouraging translation of the bolsters when the at least one cable is placed under tension.

13. A cushion according to claim 12, wherein the groove comprises a substantially horizontal channel and one or more hollow portions extending substantially vertically downwards from the base of the channel.

14. A cushion according to any one of the preceding claims, wherein the central support portion and bolsters are integrally formed.

15. A seat for a vehicle, the seat comprising a seat cushion according to any one of claims 1 to 14 and a tensioning mechanism connected to the at least one cable for tensioning the at least one cable to force the bolsters towards the support portion.

16. A seat according to claim 15, wherein one end of the or each cable is fixed to a base of the seat and the other end is connected to the tensioning mechanism.

17. A seat according claim 15 or claim 16, wherein the tensioning mechanism comprises a twin cable puller.

18. A vehicle comprising a seat cushion according to any one of claims ito 14, or comprising a seat according to any one of claims 14 to 16.

19. A seat cushion substantially as hereinbefore described with reference to the accompanying drawings.

20. A seat for a vehicle substantially as hereinbefore described with reference to the accompanying drawings.

21. A vehicle substantially as hereinbefore described with reference to the accompanying drawings.