Patent ID: 8267476

Claim:
A vehicle seat reclining device that is capable of connecting a seat back of a vehicle seat to a fixed body such as a seat cushion and a floor such that a tilt angle of the seat back can be adjusted, comprising: two connecting elements respectively having disk-shaped portions that are respectively integrally connected to the seat back or the fixed body and are oppositely coupled to each other so as to be rotatable relative to each other, engagement teeth members disposed between the two connecting elements, the engagement teeth members being attached to one of the connecting elements while circumferentially supported, so as to prohibit relative rotation of the connecting elements when outer circumferential toothed surfaces formed therein are meshed with inner circumferential toothed surfaces formed in the other of the connecting elements, and a pressure cam capable of pressing the engagement teeth members radially outwardly when moved by biasing, so as to mesh with the inner circumferential toothed surfaces formed in the other of the connecting elements, wherein the pressure cam is attached to one of the connecting elements and is movable on a linearly oscillating path in a direction perpendicular to moving directions of the engagement teeth members, wherein each of the engagement teeth members has a hardness greater than the pressure cam, and wherein when a large load capable of forcibly rotationally displacing the other of the connecting elements is applied thereto while the engagement teeth members engage the other of the connecting elements, the engagement teeth members are pressed by the other of the connecting elements in a radially inward direction in which the engagement teeth members are disengaged therefrom, so as to press the pressure cam with an increased buckling strength and plastically deform the same.