Vehicle seat including a pivoting back urged forwards by a torsion bar

A vehicle seat comprising two opposite sides, the seat including a back mounted on a seat proper to pivot about a transverse horizontal pivot axis by a locking mechanism that can be moved between a locked position in which said locking mechanism prevents the back from moving relative to the seat proper, and an unlocked position in which said locking mechanism leaves the back free to pivot relative to the seat proper about the pivot axis, the back being urged forwards by a torsion bar constituted by a metal wire which has two ends fixed respectively to the back and to the seat proper, at said opposite sides of the seat, wherein the metal wire constituting the torsion bar has a central portion extending substantially parallel to the pivot axis between first and second lever arms, each lever arm extending in a general direction that is substantially perpendicular to the pivot axis, from the central portion up to one of the ends of the torsion bar, said metal wire forming at least one spiral including a plurality of adjacent turns wound around a central axis on more than 360° between the central portion and the first lever arm, said central axis being disposed perpendicularly to the central portion of the torsion bar and being offset from said central portion of the torsion bar by a certain non-zero offset distance, the spiral comprising a portion adjacent to the central portion of the torsion bar in which the turns touch one another, and a portion which is remote from said central portion of the torsion bar and in which the turns are spaced apart from one another.