Play-free articulation for a seat with tipping backrest and its application to a seat with a backrest which can also be inclined

Play-free articulation for a seat (10) with a seat part (11) and with a backrest (12) which can be tipped and can move between an upright position and a position in which it is folded-down relative to the seat part (11), which essentially comprises a fitting (20) made of a fixed flange (21) adapted to be secured to the seat part (11) and a movable flange (22) adapted to be associated with the backrest (12), a bearing (30) made of a male part (31) and of a female part. (32) interacting freely with one another with play and one of which is carried by one of the flanges (21, 22) and the other of which is carried by the other of the flanges (21, 22), a lock (40) made of a fixed stop piece (41) and of a movable latch (42) interacting with one another and one of which is carried by one of the flanges (21, 22), and the other of which is carried by the other of the flanges (21, 22) as well as an elastic urging means (43) acting on the latch (42) and tending to apply the latter against the stop piece (41) in order to immobilize the backrest (12) in the upright position and an operating member (50) acting on the latch (42) counter to the elastic urging means (43) in order to separate the latch (42) from the stop piece (41) so as to be able to tip the backrest (12) from its upright position into its folded-down position, the device being characterized in that at least one of these male (31) and female (32) parts of the bearing (30) has a non-circular configuration, and in that the stop piece (41) of the lock (40) has a cam-shaped profile and the latch (42) of the lock (40) has a cam-follower-shaped profile intended to interact with the cam-shaped profile of the stop piece (41), and in that the bearing (30) and the lock (40) are placed relative to one another in such a way that when the cam-shaped profile and cam-follower shaped profile of the stop piece (41) and of the latch (42) of the lock (40) are applied against one another by the elastic urging means (43), the male part (31) and the female part (32) of the bearing (30) tend to move relative to one another in a direction which takes up the play between these male (31) and female (32) parts.