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 projected guide portion formed in said lower base arm, said projected guide portion extending in a diametrical direction along a diameter of said circle along which said arcuate inwardly toothed portion is formed in the lower base arm;
- a lock gear means which includes:
- an outwardly toothed portion for meshed engagement with said arcuate inwardly toothed portion of said lower base arm;
- a contact area projecting from a first side of said lock gear means;
- a first slide means disposed in said diametrical direction, said first slide means comprising an elongated hole through which said shaft is slidably inserted;
- and
- a second slide means disposed in said diametrical direction, said second slide means comprising a slide recession formed at a second side of said lock gear means opposite to said first side of the lock gear means where said contact area is formed;
- said projected guide portion of said lower arm being slidably fitted in said slide recession of said second slide means;
- wherein said lock gear means is movable via said first and second slide means in said diametrical direction, bringing said outwardly toothed portion to and out of a meshed engagement with a part of said arcuate inwardly toothed portion, 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 contact area of said lock gear means;
- an engagement guide means for engaging said cam means with said lock gear means and guiding said lock gear means in said diametrical direction;
- and
- a connecting means for connecting said cam means to said operation lever,
- wherein when not in use, said operation lever is retained at said non-use position under a biasing force of said biasing means, which in turn biasingly causes said outwardly toothed portion of said lock gear means to be in a meshed engagement with a part of said arcuate inwardly toothed portion, via said-first and second slide mean, while also biasingly causing said cam end of said-cam means to pressingly contact said contact area of said lock gear means to thereby assist in retaining said outwardly toothed portion in the meshed engagement with said part of said arcuate inwardly toothed portion, and wherein rotation of said operation lever about said shaft from said non-use position causes said lock gear means to be displaced in said diametrical direction via said first and second slide means as well as via said engagement guide means, thereby bringing said outwardly toothed portion out of the meshed engagement with said inwardly toothed portion, while simultaneously causing said cam means to rotate about said shaft in a direction to bring said cam end thereof out of contact with said contact area of said lock gear means.