Patent attributes
An internal gear includes a thin annular portion and a thick annular portion whose outside diameters are the same and whose inside diameters are different are continuously provided integrally in an axial direction, and an outer peripheral surface of the thin annular portion and the thick annular portion is formed in a substantially L shape in a flush cross section. Therefore, a conventionally substantially convex section formed with the memory internal teeth does not become the weak point in terms of strength. An axial outer end surface of the thick annular portion of the internal gear is formed to be substantially flat, and the coupling cover member is fixed to the thick annular portion to be coupled to a frame of a seat cushion or a seat back.