A reclining device for a seat, comprising:
- a shaft;
- a base having a housing defined thereon, said shaft is rotatably inserted through said base housing,
- a female lock plate rotatably supported on said shaft with respect to said base housing, said female lock plate having an inwardly toothed portion of a generally circular configuration formed therein relative to a central axis of the shaft;
- a male lock means having an outwardly toothed portion of a generally circular configuration formed toward a first side of said male lock means for a full meshed engagement with said inwardly toothed portion said female lock plate, said male lock means being so provided on said shaft so as to be rotatable thereabout and movable in a longitudinal direction thereof, wherein a second side of said male lock means is movably accommodated in said base housing;
- a guide means defined between said base housing and said second side of said male lock means which is opposite to said first side;
- said guide means including:
- at least one protuberant guide portion which is formed on said second side of said male lock means;
- and
- at least one guide recession which is formed in base housing;
- wherein said at least one protuberant guide portion is slidably fitted in said at least one guide recession, such as to permit non-rotational movement of said male lock means along the longitudinal direction of said shaft in a direction towards and away from said female lock plate,
- an operation lever integrally connected to said shaft;
- and
- an actuation means for causing said male lock means to move in the longitudinal direction of said shaft along said guide means so as to bring said outwardly toothed portion to and out of meshed engagement with said inwardly toothed portion,
- said actuation means including:
- a cam means engaged to said shaft as to be rotatable together with said shaft within said base housing, said cam means having at least one projected cam surface thereon;
- a cam follower means defined in said second side of said male lock means, said cam follower means having at least one engagement region and at least one disengagement region disposed with respect to said at least one projected cam surface of said cam means;
- and
- a biasing means for biasing said male lock means away from said female lock plate,
- wherein, when not in use, said at least one projected cam surface of said cam means is set at said at least one disengagement region of said cam follower means, whereby said male lock means is retained, while overcoming a biasing force of said biasing means, in a locked state where said outwardly toothed portion thereof is retained in a meshed engagement with said inwardly toothed portion of said female lock plate, and when in use, rotation of said operation lever of said operation lever causes said cam means to be rotated relative to the said cam follower means, thereby rotatively displacing said at least one projected cam surface towards and into engagement with said at least one engagement region of said cam follower means, whereby said male lock means is displaced under the biasing force of said biasing means along a longitudinal axis of said shaft in a direction away from said female lock plate so as to bring said outwardly toothed portion out of the meshed engagement with said inwardly toothed portion of said female lock plate.