A flat spring member (40) mainly serving as a vibration absorptive function at a normal use is engaged with a supporting frame member (130) which displaces backward along with deformation of a seat back (20) by backward moment applied to the seat back (20), and the other end is engaged with a front edge frame (102) disposed in the vicinity of the front edge of a cushion frame. Therefore, when an impact force from front or back equal to or more than that prescribed is applied, the flat spring member (40) increases in tension by backward moment applied to the seat back (20), and serves as a function to increase again the intensity of the backward moment of the seat back (20), which was once lowered by deformation of the side frame (101) of the cushion frame.
In an automobile seat provided with a seatback having a metal-made seatback frame of a substantially quadrilateral shape, the seatback frame comprising a pair of spaced apart left and right side frame sections 10a, 10b, an upper frame section 11 interconnecting upper end portions of the side frame sections 10a, 10b, and a lower frame section 12 interconnecting lower end portions of the side frame sections 10a, 10b, the lower frame section comprises a horizontally extending body arranged between the lower end portions of the side frame sections 10a, 10b, side bracket portions 12a, 12b provided at left and right ends of the horizontally extending body so as to project forward from the horizontally extending body, the side bracket portions 12a, 12b being applied and fixed to the lower end portions of the side frame sections 10a, 10b, and a structure for serving to facilitate deformation of the seatback in the event of a car crash or the like in order to absorb impact caused by the car crash or the like, the structure comprising a recess portion 13 which extends along the horizontally extending body and around the side bracket portions, and the recess portion being formed into a semi-circular shape in cross-section.
A cross member assembly for adjusting a reclinable vehicle seat includes a joint. The joint permits the cross member assembly to deflect during a vehicle impact if the reclinable vehicle seat is occupied.
