Patent ID: 8870287

Claim:
A vehicle seat reclining device arranged on a vehicle seat including a seat cushion and a seat back, the vehicle seat reclining device comprising: a first arm fixed to one of the seat cushion and the seat back of the vehicle seat, wherein the first arm includes a plurality of guide grooves; a second arm fixed to the other one of the seat cushion and the seat back of the vehicle seat and supported by the first arm in a rotatable manner, wherein the second arm includes internal teeth; first and second poles respectively guided by the plurality of guide grooves to be movable in a radial direction, wherein each of the first and second poles includes external teeth that are engageable with and disengageable from the internal teeth of the second arm; a cam body engaged with the first and second poles, wherein the cam body presses the first and second poles outwardly during a locking operation performed when rotated in a first direction to engage the internal teeth with the external teeth, and the cam body pulls the first and second poles inwardly during an unlocking operation performed when rotated in a second direction to disengage the internal teeth from the external teeth; and a restricting member arranged between the first pole and the second arm, wherein the restricting member restricts radially outward movement of the first pole when a relative rotation angle of the first arm and the second arm is within a predetermined range to prohibit engagement of the external teeth of the first pole and the internal teeth, wherein when the restricting member restricts radially outward movement of the first pole and restricts rotation of the cam body, engagement of the external teeth with the internal teeth is prohibited in the second pole, and when the first pole reaches a position corresponding to an engagement prohibition state of the external teeth and the internal teeth caused by the restricting member during an unlocking operation, a movement amount by which the second pole moves away from the internal teeth in the radial direction is set to be greater than a movement amount by which the first pole moves away from the internal teeth in the radial direction.