Double articulation for the folding backrest of a rear seat for motor vehicles

Claim 1

A double articulation for the folding backrest (5) of a rear seat (1) for motor vehicles, the seat including: - a seat element or squab (2) the front of which is articulated to the body of the vehicle about a transverse axis (4) so as to be movable between a position of normal use adjacent the floor (3) and a substantially vertical position into which it is pivoted forwardly, and - the articulation (6) being intended to connect the lower portion (5a) of the backrest (5) to the motor-vehicle body and including a first transverse articulation pin (8) and a second articulation pin (9) parallel to and spaced downwardly of the first (8), - so that the backrest (5) can selectively adopt: - a substantially vertical position of normal use, - a first lowered position in which the backrest (5) bears on the squab (2) and which can be attained as a result of the forward pivoting of the backrest (5) about the first articulation pin (8), and - a second lowered position in which the backrest (5) bears directly on the floor (3), and which can be attained by arranging the squab (2) in its substantially vertical position and then pivoting the backrest (5) forwardly about the second articulation pin (9), - the double articulation being characterised in that : - the first and second articulation pins (8, 9) are both fixed to the backrest (5) of the seat (1) and are both free to move relative to guide means which are intended to be fixed to the body, - the guide means include first and second guide tracks (14, 15) for the first and second articulation pins (8, 9) respectively, the first and second guide tracks (14, 15) being shaped as arcs of circles centred on the axes of the second and first articulation pins (8, 9) respectively, with reference to the base positions of the pins (8, 9) when the backrest (5) is in the vertical position, - the guide tracks (14, 15) also have respective ends with stop surfaces (12, 13) which define the base positions of the two articulation pins (8, 9) when the backrest (5) is in the vertical position, - whereby the backrest (5) can pivot about the first articulation pin (8) to move to its first lowered position, in which case the first articulation pin (8) remains in its base position and the second articulation pin (9) moves away from its base position along the second guide track (15), or about the second articulation pin (9) to move to its second lowered position, in which case the second articulation pin (9) remains in its base position and the first articulation pin (8) moves away from its base position along the first guide track (14), means (2b, 12) being provided for restraining the first articulation pin (8) in its base position when the squab (2) is in its position of normal use.