Vehicle seat assembly having a cradle seat back

A seat assembly for supporting a seat occupant in an automotive vehicle comprising:

• a seat cushion for supporting the seat occupant on said seat assembly;
• a seat back extending longitudinally between a lower portion operatively coupled to said seat cushion and an upper portion for supporting the seat occupant in an upright position;
• said seat back including an outer peripheral frame member, an inner occupant support frame operatively connected and supported by said outer peripheral frame member and movable from an occupant support position to an impact displacement position extending rearwardly of said outer peripheral frame member, said outer peripheral frame member includes an inboard side support bar spaced from an outboard side support bar and interconnected at one end by a upper support bar to define a generally U-shaped outer peripheral frame member, a displacable connection member operatively connecting said inner occupant support frame and said outer peripheral frame for maintaining said inner occupant support frame in said occupant support position during normal seat occupant use and for providing movement of said inner occupant support frame to said impact displacement position in response to a predetermined impact load exerted on said seat assembly, said displacable connection member includes a lateral torsion spring element having a torsion support bar having opposite ends and extending laterally between said opposing spaced apart side support bars and a torsion bar extending from each end of said torsion support bar to said respective adjacent side support bar and a spring coil interconnecting each of said torsion bars to said respective side support bar for providing resilient displacement of said inner occupant support frame between said occupant support position and said impact displacement position, and wherein said inner occupant support frame includes a pair of generally parallel spaced apart and longitudinally extending wire rods positioned between said inboard and outboard side support bars and extending between a first end coupled to said lateral torsion support bar and a second end operatively coupled to said upper support bar of said outer peripheral frame.