Vehicle seat comprising an adjustable backrest shape

1. A vehicle seat comprising:

a seat frame having a sitting surface frame and a backrest frame, wherein the backrest frame has at least one left backrest longitudinal strut, at least one right backrest longitudinal strut, an upper cross strut, and a lower cross strut, the right and left backrest longitudinal struts being pivotably arranged on the seat frame against a resistance in such a way that the backrest frame is helically deformable in the direction of height,

wherein the lower cross strut has a central region and two angled regions which are angled therefrom in a seat longitudinal direction, and wherein the left backrest longitudinal strut is arranged on a first region of the two angled regions so as to be privotable about a first axis and the right backrest longitudinal strut is arranged on a second region of the angled regions so as to be pivotable about a second axis which is different from the first axis.

2. The vehicle seat according to claim 1 , wherein the backrest frame has a central backrest longitudinal strut which is attached pivotably about a horizontal axis to the lower cross strut, the right and left backrest longitudinal struts being arranged at least in the region of upper ends of the right and left backrest longitudinal struts and outside a fictitious surface element formed by a 360° rotation of the central backrest longitudinal strut.

3. The vehicle seat according to claim 2 , wherein the upper cross strut is divided into two portions including a first, a cross strut part arranged between the left backrest longitudinal strut and the central backrest longitudinal strut and a second cross strut part arranged between the right backrest longitudinal strut and the central backrest longitudinal strut.

4. The vehicle seat according to claim 3 , wherein the cross strut part is held, in receiving portions on the left backrest longitudinal strut and the central backrest longitudinal strut, and in that the cross strut part is held, in receiving portions on the right backrest longitudinal strut and the central backrest longitudinal strut.

5. The vehicle seat according to claim 4 , wherein the first cross strut part and the second cross strut part are each held in the receiving portions in an articulated manner.

6. The vehicle seat according to claim 2 , wherein the central backrest longitudinal strut is constructed in a substantially planar manner as a longitudinal component.

7. The vehicle seat according to claim 2 , wherein at least one of the backrest longitudinal struts and the cross struts are made of metal or plastic material.

8. The vehicle seat according to claim 2 , wherein the backrest longitudinal struts or the cross struts are made of metal or plastic material.

9. The vehicle seat according to claim 1 , wherein the lower cross strut is pivotable with respect to the sitting surface frame about a horizontal axis which extends substantially perpendicular to a seat longitudinal direction.

10. The vehicle seat according to claim 1 , wherein the central backrest longitudinal strut is arranged on the central region, and the angle about which the two regions are angled is 45°.

11. The vehicle seat according to claim 1 , wherein the left backrest longitudinal strut is substantially planar and an upper end thereof is angled about an angle with respect to a lower end, and wherein the right backrest longitudinal strut is substantially planar and an upper end thereof is angled about an angle with respect to a lower end.

12. The vehicle seat according to claim 1 , wherein the cross strut is constructed as an integral component of the sitting surface frame, and in one piece therewith or with a part thereof.

13. The vehicle seat according to claim 1 , wherein the cross strut is arranged on the sitting surface frame as a separate component.

14. The vehicle seat according to claim 13 , wherein the cross strut is arranged by means of angle brackets in which said cross strut is pivotably held about a horizontal axis.

15. A vehicle comprising at least one vehicle seat according to claim 1 .

16. A vehicle seat comprising:

a seat frame having a sitting surface frame; and

a backrest frame comprising:

a left backrest longitudinal strut;

a right backrest longitudinal strut;

an upper cross strut; and

a lower cross strut including a central region, a right angled region interconnected to a right end of the central region, and a left angled region interconnected to a left end of the central region, wherein the right angled region and the left angled region are angled toward a center of the central region, wherein the left angled region is in a first plane and the right angled region is in a second plane that is different from the first plane,

wherein a lower portion of the left backrest longitudinal strut is interconnected to the left angled region at a left pivot point such that the left backrest longitudinal strut is rotatable about a first axis extending through the left pivot point and oriented perpendicular to the first plane;

wherein a lower portion of the right backrest longitudinal strut is interconnected to the right angled region at a right pivot point such that the right backrest longitudinal strut is rotatable about a second axis extending through the right pivot point and oriented perpendicular to the second plane.