Patent ID: 7543890

Claim:
A structure of automotive seat of fold-down type allowing a seat back thereof to be folded down onto a seat cushion thereof, comprising: a seat back frame member provided in said seat back; a base plate disposed at said seat cushion; said seat back frame member being rotatably connected with said base plate so as to be rotatable relative to the base plate in either of a forward direction of said automotive seat and a backward direction of said automotive seat; a limit means for defining a backward limit point for limiting inclination of said seat back frame member in said backward direction of said automotive seat; a first engagement element formed in said seat back frame member; a second engagement element formed in said base plate, said second engagement element being disposed at a predetermined point distant from said first engagement element in said forward direction of said automotive seat; a spiral spring element adapted for giving a biasing force to said seat back frame member to thereby biasingly cause said seat back to rotate in said forward direction of said automotive seat towards said seat cushion; and said spiral spring element having: a stationary inward end portion defined centrally thereof, said stationary inward end portion being securely connected with said base plate; and a movable outward end portion defined circumferentially thereof, said movable outward end portion being releasably engaged with said first engagement element; wherein said biasing force of said spiral spring element is effectively applied to said seat back frame member in so far as said particular seat back frame member is positioned within a range between said backward limit point and said predetermined point, and wherein rotation of said seat back frame in said forward direction causes simultaneous displacement of said first engagement element, which in turn allows said movable outward end portion of said spiral spring element to be displaced under said biasing force, together with said first engagement element, in a direction toward said second engagement element, and then, engagement of said movable outward end portion with said second engagement element blocks application of said biasing force to seat back frame member, whereupon said seat back is stopped temporarily at said predetermined point, while on the other hand allowing said first engagement element to be disengaged from said movable outward end portion of the spiral spring element, to thereby allow said seat back frame or said seat back to be folded down from said predetermined point towards said seat cushion.