Reclining device for vehicle seat

A reclining device for a vehicle seat, which includes an upper arm to be fixed to a seat back of the seat and a lower base arm to be fixed to a seat cushion of the seat, said upper arm being rotatable via a shaft with respect to said lower base arm, said reclining device comprising:

• an arcuate inwardly toothed portion which is formed in said upper arm, generally along a circle having a center at an axis of said shaft;
• a lock gear means having one end portion supported rotatably upon a pin which is fixed to said lower base arm such as to be disposed apart from said shaft, and further having another end portion formed with an outwardly toothed portion, wherein said lock gear means is rotatable about said pin to bring said outwardly toothed portion to and out of a meshed engagement with a part of said arcuate inwardly toothed portion of said upper arm, to thereby lock and unlock said upper arm with respect to said lower base arm;
• an operation lever having a base end portion rotatably connected to said shaft;
• a biasing means for normally biasing said operation lever to a non-use position;
• and
• an interlocking means arranged between said lock gear means and said operation lever, said interlocking means including:
• a cam means rotatably provided on said shaft, said cam means having a cam end for contact with said lock gear means;
• a guide means for guiding said lock gear means in a direction to disengage said outwardly toothed portion of the lock gear means from said arcuate inwardly toothed portion of said upper arm, said guide means comprising a first guide means projected from said lock gear means and a second guide means for engagement with said first guide means and said operation lever, wherein said second guide means is so interlocked with said operation lever that rotation of the operation lever permits said first guide means to cooperate with said second guide means in an engagement relation therewith so as to cause disengagement of said outwardly toothed portion from said arcuate inwardly toothed portion, and
• a connecting means for connecting said cam means to said operation lever,
• wherein said cam means is normally retained under a biasing force of said biasing force of said biasing means, causing said cam end to pressingly contact said lock gear means, thereby retaining said outwardly toothed portion of said lock gear means in a meshed engagement with a part of said arcuate inwardly toothed portion, and wherein, when said operation lever is rotated about said shaft from said non-use position, said cam means is rotated about said shaft in a direction to bring the cam end thereof out of contact with said lock gear means, while at the same time, said lock gear means is caused by said guide means to rotate about said pin to bring the outwardly toothed portion thereof out of the meshed engagement with said arcuate inwardly toothed portion.