Seat reclining device for vehicle

A seat reclining device for a vehicle, arranged at a region where a seat cushion frame and a seat back frame, which constitute a vehicle seat having a seat cushion and a seat back, are connected with each other, to allow an angle of the seat back to be adjusted in forward and rearward directions, the device comprising:

• an upper toothed bracket fastened to a lower end of the seat back frame;
• a lower toothed bracket fastened to a rear end of the seat cushion frame;
• an operating section interposed between the upper and lower toothed brackets, for allowing the seat back to be reclined;
• and
• a cover plate for covering the upper and lower toothed brackets and the operating section;
• wherein the operating section comprises upper teeth internally formed on a circumferential inner surface of a groove which is depressed on the upper toothed bracket;
• lower teeth externally formed on a circumferential outer surface of a protrusion which projects from the lower toothed bracket toward the upper toothed bracket and is received in the groove of the upper toothed bracket, in a manner such that the lower teeth can be meshed with the upper teeth;
• a pair of cams accommodated in a cam hole which is defined at a center portion of the lower toothed bracket, to rotate the lower teeth of the lower toothed bracket in a desired reclining direction;
• and a cam spring having both ends which are respectively fitted into spring holes defined in the cams, to bias the cams in opposing radial outward directions;
• and
• wherein each cam has a shaft hole through which an operating shaft is fitted;
• a boss which is formed around the shaft hole on a surface of the cam;
• an operating cam part which is formed on a circumferential outer surface of the cam to extend through a first predetermined angle and is brought into contact with a circumferential inner surface of the lower toothed bracket, defining the cam hole, the operating cam part having an eccentric center which is deviated from a center of the cam hole, to serve as a wedge;
• a concentric part which is formed on a surface of the operating cam part, farthest from the boss, to extend through a second predetermined angle less than the first predetermined angle, and has a stepped portion in a manner such that concentric parts of the pair of cams can be brought into contact with each other;
• and a key groove which is defined to be communicated with the shaft hole in a manner such that a key integrally formed on the operating shaft can be received in the key groove to operate the cam toward a recline permitting position.