Reclining device for a vehicle seat

Claim 1

A reclining device for a vehicle seat including a back frame longitudinally rotatably journaled relative to a cushion frame, said reclining device comprising: a cam having at least three working surfaces which differ from one another in amount of displacement, said cam is rotatably connected on one of said back frame and said cushion frame by a bracket member at a predetermined distance from a connecting point where said back frame is rotatably connected to said cushion frame, and said cam further having an arc-shaped guide groove perforated therein, the arc center of which is disposed cocentrically relative to the center of rotation of said cam, said arc-shaped guide groove having a plurality of recessed portions formed therein, each of said recessed portions arranged in a corresponding relationship with the respective working surfaces of said cam; an elongated guide hole on said bracket member corresponding crosswise to said arcshaped guide groove of said cam; a cam engagement portion provided in the other of said back frame and said cushion frame, said cam engagement portion positioned to engage with said cam; a shaft, rotatably supported, extending through said arcshaped guide groove and said elongated guide hole such that said shaft is slidable along said arc-shaped guide groove while at the same time slidable along said elongated guide hole in a cooperative manner, and, when said cam is rotated with one of said working surfaces thereof being brought into engagement with said cam engagement portion, said shaft is then biased by a spring means into engagement with one of said plurality of recessed portions corresponding to said one of said working surfaces; and a hook means for retaining said cam into engagement with said cam engagement portion, said hook means rotatably mounted to said shaft and further at a tip end thereof engaged with a portion of said cam engagement portion.