Patent ID: 8651578

Claim:
A seat reclining apparatus for a vehicle, comprising: a first arm configured to be fixedly attached to one of a seat cushion and a seatback; a second arm configured to be fixedly attached to the other one of the seat cushion and the seatback, the second arm rotatably supported by the first arm; a pawl, of which movement in a radial direction is guided by a guide wall provided at the first arm, including external teeth which are provided at a radially outer surface of the pawl and are engageable with internal teeth provided at the second arm, the pawl including a cam portion formed at a radially inner surface of the pawl and the cam portion includes a plurality of pawl-side cam surfaces arranged in a circumferential direction of the cam portion; a cam engaging with the pawl and rotatably provided at a central portion of the first arm, the cam including a cam surface engaging with the cam portion formed at the pawl; and a biasing member biasing the cam to rotate in one direction and causing the cam surface to press the cam portion in a radial direction in which the external teeth and the internal teeth engage with each other, wherein the plurality of pawl-side cam surfaces or the cam surface include a shape so that the plurality of pawl-side cam surfaces and the cam surface are in contact with each other when the external teeth and the internal teeth are in an engaged state, and the plurality of pawl-side cam surfaces or the cam surface include a shape so that clearances, between each of the plurality of pawl-side cam surfaces and the cam surface in the radial direction when the pawl is moved by a rotational operation of the cam against a biasing force of the biasing member in the radial direction in which the engaged state of the external teeth and the internal teeth is released, are all uniform.