Patent ID: 8016356

Claim:
A coupling apparatus, comprising: a reclining apparatus coupling a seat back and a seat cushion of a vehicle seat; the reclining apparatus includes: an inner tooth member including an inner gear coupled to one of the seat back and the seat cushion; and an outer tooth member including an outer gear configured to mesh with the inner gear of the inner tooth member and coupled to the other of the seat back and the seat cushion; the outer gear is smaller than the inner gear in a diameter thereof and is formed to have a tooth number different from a tooth number of the inner gear; and a backrest angle of the seat back is varied by a circulating movement of the outer gear on an inner tooth face of the inner gear in a state where the outer gear meshes with the inner gear, wherein: the inner gear and the outer gear constitute a gear train and mesh with each other for enabling transmission of a power; the inner gear and the outer gear have tooth shapes formed such that a meshing line defined by meshing of the inner gear and the outer gear is configured as a spiral meshing line, the spiral meshing line extending circumferentially from a first point on a first curve positioned on a radially inner side of the inner gear and intersecting a second point on a second curve positioned on a radially outer side of the outer gear, the spiral meshing line extending in a direction in which a distance between the first curve and the second curve becomes larger, and the first curve and the second curve defining a meshing region; the inner gear projects in a circular cylinder shape towards the outer gear, and the outer gear projects in a circular cylinder shape towards the inner gear; the inner tooth member includes a cylinder portion in a circular cylinder shape projecting from a center portion of the inner gear, the outer tooth member includes a through hole in a circular shape at a center portion of the outer gear for receiving therein and surrounding the cylinder portion of the inner tooth member, and the cylinder portion and the through hole have a positional relationship in which their center portions are offset from each other; and within a gap between the cylinder portion of the inner tooth member and the through hole of the outer tooth member surrounding the cylinder portion, a pair of eccentric members each having a shape that fills a portion of the gap are disposed, the pair of eccentric members being urged to wedge into narrowed portions of the gap and are maintained in a state where the outer gear is pressed against the inner tooth face of the inner gear, at least one of the eccentric members is configured to be pushed in a circumferential direction by a rotational operation of a shaft pin provided in a cylinder of the cylinder portion, and the at least one of the eccentric members is further configured to be released from a wedging state and to press against an inner peripheral face of the through hole of the outer tooth member to cause circulating movement of the outer gear.