Device for articulated connection between the backrest and the seat part of a vehicle seat

A device for articulating connection between a backrest and a seat part of a vehicle seat in which a backrest armature comprises two uprights that are articulated with respect to a seat part armature about a first transverse horizontal articulation pin in order to define various positions of comfort and about a second articulation pin, parallel to the first articulation pin, in order to allow the backrest to be folded down onto the seat part, the latter articulation being associated with unlockable immobilizing means, wherein, for each upright, a first articulation with respect to the seat part armature is provided by a lever including, above a lever part that is journal-mounted on the first articulation pin, a tenon of rectangular section that fits into a central housing formed in a section piece constituting the corresponding upright, whereas in a second articulation, the second articulation pin is borne by the aforementioned tenon and interacts with at least one mounting plate which, arranged against the lever, is set tightly into the housing of the section piece and is fixed by riveting, the mounting plate having a lower end protruding beyond the upright and locally fitted with toothing designed to interact with complementary toothing borne by a mechanism for immobilizing the upright with respect to the lever.