Convertible car seat

1. A convertible car seat, comprising:

a seating surface and a backrest which both run substantially perpendicular to a longitudinal plane (P);

a support including two frames, which are symmetrical with respect to a defined perpendicular plane (P), which are both quadrilateral in shape and are positioned on either side of the seating surface along planes that are substantially parallel to the plane (P), the sides of the frames being made up of rigid elements, at least one of which is positioned along a plane that is generally horizontal, with the opposite rigid element located on one of the sides of the seating surface, the rigid elements being connected to each other by means of joints positioned at each of opposite ends along an axle and comprising a set of four axles substantially parallel to each other, in such a way that the support can be folded by pivoting the rigid elements around the axles in one direction of rotation on one end of the rigid element and in the same direction of rotation on the other end, the axles comprising the following when the convertible seat is in a seat configuration:

a first axle that connects the rigid elements located in front of the seat to the substantially horizontal rigid elements,

a second axle that connects the rigid elements located to the rear of the seat to the substantially horizontal rigid elements,

a third axle and a fourth axle which connect the rigid elements located in front of the seat and the rigid elements located to the rear of the seat to the rigid elements located on either side of the seat wherein:

at least one of the joints of the rigid elements is lockable in such a way as to lock the support in a given position,

the seating surface is mounted lockably connected to the mentioned third axle,

arms are placed on either side of the seat, along longitudinal planes, with a first end of each arm lockably connected to the fourth axle, and

the backrest is mounted on the second end of arms by means of at least one lockable joint to form a fifth axle which is substantially parallel to the other axles, in order to unlock one or more of the lockable joints to enable the support, the seating surface the arms and the backrest to be placed in various positions, and locking one or more of the lockable joints enables the support, the seat, the arms and the backrest of the seat to be fixed in a given configuration.

2. A convertible seat according to claim 1 , characterized in that its flat configuration consists of at least two positions:

one, high, in which the frames open out upwards,

another, low, in which the frames are folded downwards.

3. A convertible seat according to claim 1 , characterized in that the rigid elements located on a horizontal plane are guided along longitudinally parallel rails, which allow the convertible seat to be moved along such rails, and that at least one of the joints located on said horizontal plane is lockable on the mentioned rail.

4. A convertible seat according to claim 1 characterized in that the fourth axle includes means that make it possible to releasably hook the rear part of the seating surface and the bottom part of the backrest to the mentioned axle.

5. A convertible seat according to claim 1 characterized in that at least one of said lockable rigid elements is combined with the lockable joint of the seating surface.

6. A convertible seat according to claim 1 characterized in that the locking/unlocking of at least the joints of the first and second ends of the arms is coordinated.

7. A convertible seat according to claim 6 that characterized in that a series of means are provided in order to make the movements of the backrest and the arms interdependent.

8. A vehicle including at least one seat in accordance with claim 1 .

9. A method for transforming a convertible seat according to claim 1 to either the seat, shelf, document case or flat configurations, that characterized in that it includes the successive steps of unlocking one or several of the lockable joints, repositioning the seating surface and/or the backrest, and locking said lockable joint or joints.

10. A method for transforming a convertible seat according to claim 1 from a seat configuration to a shelf configuration that characterized in that it consists of:

unlocking the joints located on the fourth and fifth axles,

pivoting the backrest and the arms around the fifth and fourth axles respectively in one direction of rotation on one end of the rigid element and in the same direction of rotation on the other end and, when the back of the backrest is horizontal,

locking the joints located on the fourth and fifth axles.

11. A method for transforming a convertible seat according to claim 1 , from a seat configuration to a flat configuration that characterized in that it consists of:

unlocking the joints located on the third, fourth and fifth axles,

pivoting the seating surface around the third axle,

pivoting the backrest and the arms around the fifth and fourth axles respectively and, when the back of the seating surface and the back of the backrest are on the same horizontal plane,

locking the joints located on the third, fourth and fifth axles.

12. A method for transforming a convertible seat according to claim 11 , from the flat configuration to a fold-away flat configuration that characterized in that it consists of:

unlocking at least one of the mentioned joints of the rigid elements,

folding the frames downwards and, when the lowest position is reached, locking at least one of said joints of the rigid elements.

13. A method for transforming a convertible seat according to claim 1 , from a seat configuration to a document case configuration that characterized in that it consists of:

unlocking the joints located on the third and fourth axles,

detaching the rigid elements in front of the substantially horizontal rigid elements,

pivoting the seating surface until it is substantially vertical and close to the backrest,

locking the joints located on the third and fourth axles.

14. A method for transforming a convertible seat according to claim 1 characterized in that the inclination of the seating surface and the backrest can be adjusted by unlocking and then locking at least one of the joints located on the third and fifth axles respectively.

15. A method for transforming a convertible seat according to claim 1 characterized in that the height of the seating surface can be adjusted by unlocking and then locking at least one of the joints of the rigid elements.

16. A convertible seat according to claim 1 characterized in that it includes a first rod substantially located on the extension of at least one of the mentioned rigid elements located to the rear of the seat, where such rod has on its open end a first cogwheel designed to work together with a second cogwheel mounted on the mentioned fifth axle formed integral with the backrest, with a third cogwheel mounted on said third axle formed integral with the seating surface and designed to work together with a fourth cogwheel mounted on the end of the relevant rigid element located in front of the seat, with a second rod connected to the backrest of the seat and to the rigid element located on the relevant side of the seat in such a way that it forms a foldable quadrilateral with the aforementioned first rod.