Seat reclining mechanism

A seat reclining mechanism designed to be mounted to a seat cushion and a seat back so as to allow said seat back to be reclined, said seat reclining mechanism comprising:

• a guide bracket adapted to be mounted to either one of said seat cushion and said seat back;
• an internal gear member adapted to be mounted to a remaining one of said seat cushion and said seat back, said internal gear member being coupled to said guide bracket in a rotatable manner about a rotation axis thereof with respect to said guide bracket, and formed with internal teeth along a circle having a center on said rotation axis;
• a plurality of lock gear members disposed between said guide bracket and said internal gear member to extend radially from said rotation axis, each of said lock gear members being formed with external teeth meshingly engageable with said internal teeth, and supported by said guide bracket in such a manner as to be slidable in both a lock direction causing said external teeth to be brought into meshing engagement with said internal teeth and an unlock direction causing said external teeth to be released from the meshing engagement with said internal teeth;
• a rotatable cam rotatably supported by either one of said guide bracket and said internal gear member, and adapted to be rotatable in both a lock-causing rotation direction causing said lock gear members to be slidingly moved in said lock direction and an unlock-causing rotation direction causing said lock gear members to be slidingly moved in said unlock direction;
• a lock spring biasing said rotatable cam in said lock-causing rotation direction;
• a forwardmost-inclination stopper protrusion and a rearwardmost-inclination stopper protrusion which are provided on either one of said guide bracket and said internal gear member;
• and
• a stopper plate fixed to a remaining one of said guide bracket and said internal gear member, said stopper plate having a forwardmost-inclination stopper portion adapted to be brought into contact with said forwardmost-inclination stopper protrusion when said seat back is at a forwardmost inclined position, and a rearwardmost-inclination stopper portion adapted to be brought into contact with said rearwardmost-inclination stopper protrusion when said seat back is at a rearwardmost inclined position.