Patent ID: 7648191

Claim:
An automobile door guard bar comprising a tube having a square cross-section perpendicular to the length of said tube; wherein said tube is made of a rigid material; said tube having two first parallel sides perpendicular to a bending input direction, said two first parallel sides perpendicular to the bending input direction each having a thickness t parallel to the bending input direction; said tube having two second parallel sides parallel to the bending input direction, said two second parallel sides parallel to the bending input direction each having said thickness t perpendicular to the bending input direction; said tube having four corners with each corner having a convex outside surface defined by radius R 1 and with each corner having a concave inside surface defined by radius R 2 ; each corner having a radial thickness t r ; and said tube simultaneously satisfying the following relations (1) to (3): R 1 ≦1.5 t (1) t R ≧1.1 t (2) R 1 ≧R 2 (3).