Backrest

Abstract

A backrest for a vehicle seat with a backrest frame including an arching element, running in a planar manner on the backrest frame with the upper and lower end sections thereof, in the backrest longitudinal direction, each fixed to the backrest, or to a component arranged on the backrest and an adjuster device with which the arching of the arching element may be adjusted in a middle region between the both end sections thereof. At least one limiting element is provided on the backrest frame with one end connected to the middle region of the arching element in order to limit the extent of the arching of the arching element.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Phase Patent Application of International Application Number PCT/DE02/03328, filed on Sep. 4, 2002, which claims priority of German Patent Application Number 101 45 207.1, filed on Sep. 7, 2001.

FIELD OF THE INVENTION

The invention relates to a backrest for a motor vehicle seat.

BACKGROUND

A backrest comprises a backrest frame; a curvature forming element which extends flat against the backrest frame and which is fixed by its upper and lower end sections (seen in the longitudinal direction of the backrest, i.e. in the extending direction of the spinal column of a person seated on the seat) on the backrest frame or on a structural element mounted on the backrest frame; as well as an adjusting device with which the curvature of the curvature forming element can be adjusted in a region between the two said end sections (hereinafter called the middle region).

With a vehicle seat of this kind there is the problem that as the bowing of the curvature forming element increases, its curvature becomes very marked in the middle region, which goes against the desired large surface area contact of the curvature forming element against the seat cushion and the large surface area support of the back of a vehicle occupant associated therewith.

SUMMARY

The object of the invention is to provide a backrest which is characterised by a large adjusting region of the curvature forming element through a large surface area support of the back of the person seated on the seat.

According to this at least one limiting element is provided on the backrest frame and is connected by one end to the middle region of the curvature forming element in order to limit the degree of bowing of the curvature forming element.

The degree of bowing which is thereby to be permitted in each individual case (i.e. with a specific backrest) is fixed through the choice of an appropriate limiting element.

In that the (preferably elongated) limiting element is fixed by one end on the seat frame or a structural assembly mounted thereon and by the other end on the middle region of the curvature forming element, the maximum extension of the limiting element across the extension plane of the backrest frame limits the maximum bowing or curvature of the curvature forming element. An increase in the curvature is equal to an increasing distance of individual points of the curvature forming element from the backrest frame. By limiting the maximum possible distance of the middle region of the curvature forming element from the backrest frame through a limiting element to a maximum value it is also possible to fix at the same time the maximum possible curvature.

By the middle region of the curvature forming element is thereby meant the entire region which extends between the upper and lower end sections of the curvature forming element (viewed in the longitudinal direction of the backrest). The middle region comprises therefore expressly not only a region surrounding the centre point of the curvature forming element, but rather any region which extends between the upper and lower end section of the curvature forming element and thus between the upper and lower fixing points of the curvature forming element and is spaced therefrom. It is however advantageous throughout if the middle region extends around the centre point of the curvature forming element.

The limiting element is preferably formed by a tightening element, e.g. in the form of a cable, belt or wire which becomes taut as the curvature of the middle region of the curvature forming element increases and which ultimately permits no additional curvature once the tension is sufficiently taut.

Furthermore the limiting element can also be formed by an elastically deformable traction means, e.g. in the form of an elastically deformable plastic rod.

Depending on which curvature is desired with a specific type of backrest it is also possible to provide several limiting elements of the said kind which can be arranged side by side both in the longitudinal direction of the backrest and across the longitudinal direction.

The solution according to the invention can be used independently of the type of adjusting device used for adjusting the curvature of the curvature forming element. For example an adjusting device can be used here where a tensioning element acts on the curvature forming element or where a curved body such as e.g. in the form of an eccentric disc serves as the adjusting element.

If a tensioning element such as a cable or wire is used as the adjusting element then the limiting element can be fixed by its end remote from the curvature forming element on the adjusting element. In this case the adjusting element for adjusting the curvature as well as the limiting element for restricting the curvature of the curvature forming element form one structural assembly which can be supplied fully pre-assembled where applicable.

The solution according to the invention is furthermore independent of whether between the backrest frame and the backrest cushion of a vehicle seat there is only one single curvature forming element on which on one side an adjusting device acts for adjusting the curvature and which on the other side bears against the backrest cushion, or whether between the backrest frame and the backrest cushion there are two or more large area elements which interact to adjust the curvature of the backrest. The limiting element provided according to the invention can be used with any type of curvature forming element which serves to fix the curvature of the backrest of a vehicle seat.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will now be explained in detail with reference to the following description of an embodiment illustrated in the drawings.

They show:

FIG. 1a a plan view of an curvature forming element for the backrest of a motor vehicle seat;

FIG. 1b a section through the curvature forming element according to FIG. 1a in a non-curved state;

FIG. 2 a section through the curvature forming element according to FIG. 1a in a markedly curved state;

DETAILED DESCRIPTION

FIGS. 1a and 1b show a large surface curvature forming element 1 which is mounted against a backrest frame 6 of a vehicle seat serving as the lordosis support for a vehicle occupant and shown only diagrammatically in FIG. 1a.

The base body of the curvature forming element 1 is substantially H-shaped and has two side sections 11, 12 which extend in the longitudinal direction L of the backrest and are connected together by a cross bar 13. The side sections 11, 12 of the curvature forming element 1 each have bent over side ends 11a, 12a and a reinforcement rib 14 and are hereby formed stiffer than the lighter bowing cross bar 13. The side sections 11, 12 of the curvature forming element 1 are thereby each partially uncoupled from the cross bar 13 through a slot 15 extending in the longitudinal direction L of the backrest.

The backrest longitudinal direction corresponds when the backrest is upright (according to the illustration in FIG. 1b) to the vertical axis of the vehicle (z-axis) which extends from the vehicle floor to the vehicle roof.

In order to adjust the bowing of the curvature forming element 1 and thus a backrest cushion P mounted in front of the curvature forming element 1, shown diagrammatically in FIG. 1b, a tensioning element 2 is provided in the form of a traction member of wire which is mounted on the backrest, more particularly on the backrest frame. The tensioning element 2 is fixed in the region of its lower end 22 through a transverse connecting element 25 and fixing elements 27 connected thereto to corresponding fixing points 17a on the lower end section 17 of the curvature forming element 1. (The fixing of the tensioning element 2 in the region of its lower end 22 to the transverse connecting element 25 is shown diagrammatically in FIGS. 1a and 2 by a black fixing spot).

The curvature forming element 1 is on the other hand fixed in the region of its upper end section 16 in the region of upper fixing points 16a to the backrest frame (not shown in the figures) of the vehicle seat by suitable fixing elements 26 which are connected together through a transverse connecting element 25′. As opposed to the lower transverse connecting element 25 however the upper transverse connecting element is not connected to the tensioning element 2.

In short the upper end section 16 of the curvature forming element 1 is fixed directly on the backrest frame through fixing points 16a and through fixing elements 26 (connected together by means of the upper transverse connecting element 25′) whilst the lower end section 17 of the curvature forming element 1 is fixed on the tensioning element 22 through fixing points 17a, fixing elements 27 and a lower transverse connecting element 25.

In order to adjust the bowing of the curvature forming element 1 a force is exerted on the tensioning element 2 by means of a manual or electric drive unit so that the lower end 22 is moved upwards along the vertical vehicle axis (z-axis) in the longitudinal direction L of the backrest. At the same time the lower end section 17 of the curvature forming element 1 is hereby raised since this is fixed on the lower end 22 of the tensioning element 2 through fixing elements 27 and the transverse connecting element 25.

The upper end section 16 of the curvature forming element 1 remains however spatially unchanged since it is fixed directly on the backrest frame through the associated connecting elements 26.

As a result by exerting a force on the tensioning element 2 upwards in the direction of the vertical vehicle axis z the lower end section 17 of the curvature forming element 1 is moved up towards its upper end section 16. The two end sections 16, 17 hereby move closer together and the curvature forming element 1 is curved or bowed to an increasing amount, see the change in the curvature forming element 1 from the non-curved state (FIG. 1b) into the curved state (FIG. 2).

Basically the increase in the bowing also leads to an increase in the curvature of the curvature forming element 1 which with a very marked curvature goes against the desired largest possible surface support of the back of a vehicle occupant over the curvature forming element.

Here however the bowing and thus in particular the curvature of the curvature forming element 1 in its middle region between the two end sections 16, 17 is restricted by two limiting elements 3, 4 (hold-down plates) which are each fixed by one end 31, 41 on the tensioning element 2 and by the other end 32, 42 on the cross bar 13 of the curvature forming element 1. The two longitudinally extended limiting elements 3, 4 are thereby mounted on the upper and lower ends of the cross bar 13 spaced from each other in the longitudinal direction L of the backrest.

In the non-curved state of the curvature forming element 1 illustrated in FIG. 1b the limiting elements 3, 4 which are made of plastic are each deformed so that despite their elongated design they are located between the tensioning element 2 and the cross bar 13.

As the bowing of the curvature forming element 1 increases, so the limiting elements 3, 4 become aligned in a straight line, see FIG. 2. The length of the limiting elements 3, 4 with a rectilinear alignment defines the maximum distance from the tensioning element 2 (and thus the backrest frame overall) which the cross bar 13 can occupy across the longitudinal direction L of the backrest. The bowing of the curvature forming element 1 is hereby restricted which increases with increasing distance of the middle region of the curvature forming element 1 from the tensioning element 2. It can clearly be seen that the curvature forming element 1 bears with a large surface area against the backrest cushion P even in the state of maximum curvature illustrated in FIG. 2, and thus enables the back of the occupant to be supported with the large surface area.

The curvature forming element 1 need therefore not adjoin the backrest cushion P directly. It is possible throughout to provide an additional backrest shell between the curvature forming element 1 and the backrest cushion P.

Furthermore the invention can be designed with any type of means for adjusting the curvature of the curvature forming element 1. The use of tensioning means 2 described here for adjusting the curvature of the curvature forming element 1 is therefore only given by way of example. When using other means for adjusting the curvature of the curvature forming element 1 the ends 31, 41 of the elongated limiting elements 3, 4 remote from the curvature forming element 1 are advantageously attached to the seat frame (backrest frame).

Claims

1. A backrest for a vehicle seat comprising:

a backrest frame;

a curvature forming element which extends with a flat area adjacent the backrest frame and which is fixed on the backrest frame or on a structural element mounted on the backrest frame by at least one of an upper end section and a lower end section in the longitudinal direction of the backrest; and

an adjusting device with which a bowing of the curvature forming element is adjusted in a middle region between the upper and lower end sections;

wherein on the backrest frame or on a structural element mounted on the backrest frame there is at least one limiting element which is connected by one end to the middle region of the curvature forming element in order to limit the extent of curvature of the curvature forming element.

2. The backrest according to claim 1, wherein the limiting element is elongated.

3. The backrest according to claim 1 or 2, wherein the limiting element is tautened as the bowing of the middle region increases.

4. The backrest according to claim 1, wherein the limiting element is elastically deformable.

5. The backrest according to claim 1, wherein the limiting element is formed by traction means which as the bowing of the curvature forming element increases exerts a tensile force on its middle region.

6. The backrest according to claim 1, wherein the limiting element is formed by one of an elastically deformable plastic element, cable, belt and wire.

7. The backrest according to claim 1, wherein the limiting element is fixed with the other end on the backrest frame or on a structural element mounted on the backrest frame.

8. The backrest according to claim 1, wherein several limiting elements are provided.

9. The backrest according to claim 8 wherein the limiting elements are mounted one behind the other in the longitudinal direction of the backrest.

10. The backrest according to claim 1 wherein the adjusting device has as an adjusting element which acts on the curvature forming element (1) one of a tensioning element and a curved body.

11. The backrest according to claim 1 wherein the limiting element is fixed with its other end on an adjusting element of the adjusting device which acts on the curvature forming element.

12. The backrest according to claim 1 wherein between the curvature forming element and a backrest cushion mounted in front of the curvature forming element there is a support element which extends over a large surface area.