Reclining device

A reclining device, comprising:

• a guide bracket that is fixedly attached to one of a seat cushion and a seatback;
• an internal gear that is fixedly attached to the other of the seat cushion and the seatback and is shiftable for relative rotation to the guide bracket;
• at least a pair of lock gears that are respectively arranged on both sides of a guide part provided on the guide bracket and movable along the guide part, each lock gear including external teeth meshable with internal teeth of the internal gear;
• and
• a cam that shifts the lock gears along the guide part between a lock position at which the internal teeth are meshed with the external teeth to regulate relative rotation and an unlock position at which the meshing between the internal teeth and the external teeth is released to allow the relative rotation,
• wherein the external teeth of the pair of lock gears each have a shape including an indentation portion on a tooth surface closer to the guide part in a tooth thickness direction so as to define a gap between the tooth surface closer to the guide part and an internal tooth of the internal gear when the lock gears are in the lock position,
• the internal gear includes a cylinder formed with the internal teeth in an inner circumferential surface thereof,
• the pair of lock gears each are arranged in an inside of the internal gear movably in a radial direction of the internal gear, and the external teeth are arranged along an arc so as to mesh with internal teeth in a section of the internal gear, and
• an external tooth which is one of external teeth of the lock gear excluding the opposite end external teeth is a reference external tooth, external teeth in a region farther away from the guide part than the reference external tooth have a circular pitch smaller than a circular pitch of the internal teeth so that the external teeth are closer to the reference tooth, and external teeth in a region closer to the guide part than the reference external tooth have a circular pitch larger than the circular pitch of the internal teeth so that the external teeth are away from the reference tooth.

A reclining device, comprising:

• a guide bracket that is fixedly attached to one of a seat cushion and a seatback;
• an internal gear that is fixedly attached to the other of the seat cushion and the seatback and is shiftable for relative rotation to the guide bracket;
• at least a pair of lock gears that are respectively arranged on both sides of a guide part provided on the guide bracket and movable along the guide part, each lock gear including external teeth meshable with internal teeth of the internal gear;
• and
• a cam that shifts the lock gears along the guide part between a lock position at which the internal teeth are meshed with the external teeth to regulate relative rotation and an unlock position at which the meshing between the internal teeth and the external teeth is released to allow the relative rotation,
• wherein the external teeth of the pair of lock gears each have a shape including an indentation portion on a tooth surface closer to the guide part in a tooth thickness direction so as to define a gap between the tooth surface closer to the guide part and an internal tooth of the internal gear when the lock gears are in the lock position,
• the internal gear includes a cylinder formed with the internal teeth in an inner circumferential surface thereof,
• the pair of lock gears each are arranged in an inside of the internal gear movably in a radial direction of the internal gear, and the external teeth are arranged along an arc so as to mesh with internal teeth in a section of the internal gear, and
• among the external teeth of each of the pair of lock gears, the external tooth closest to the guide part is a first external tooth and the external tooth farthest from the guide part is an n-th external tooth,
• the external teeth of the lock gear are arranged at a constant pitch, and the pitch is set such that the first external tooth has a tooth surface away from the guide part and coming into contact with a tooth surface of an internal tooth, and the n-th external tooth has a tooth surface away from the guide part and defining a gap against a tooth surface of an internal tooth when the lock gear is in the lock position.