Impact absorption structure of vehicle seat

An impact absorption structure of vehicle seat, comprising;

• a seat cushion frame including a side frame means;
• the side frame means having a vertical planar portion and a peripheral flange element formed in peripheral ends of the vertical planar potion, wherein the vertical planar portion includes an upper end facing to a side upwardly of the vehicle seat and a lower end facing to a side downwardly of said vehicle seat, and said peripheral flange element includes:
• an upper flange portion formed in said upper end of said vertical planar portion;
• and a lower flange portion formed in said lower end of said vertical planar portion;
• and
• a means for making said side frame means prone to deformation by an impact imparted to said seat cushion frame, said means including a centroidal line which extends vertically along a whole vertical section of said side frame means which includes a vertical section of said upper and lower flange portions, said centroidal line having an upper portion facing to the side upwardly of said vehicle seat,
• wherein said means is arranged in said whole vertical section of said side frame means as well as in said vertical section of said upper and lower flange portions, such that said upper portion of said centroidal line is inclined by a predetermined angle in a direction to a side inwardly of said seat cushion frame, and that a module of section of said lower flange portion is smaller than a module of section of said upper flange portion, thereby allowing said side frame means to be deformed by said impact toward a side outwardly of said seat cushion frame, and thus absorbing the impact.