Patent ID: 7614658

Claim:
A hollow extruded frame formed by extruding a light alloy, comprising: a peripheral wall part having an elongated shape with a short axis and a long axis in a cross section perpendicular to a longitudinal direction of the frame, wherein said long axis is longer than said short axis; and a plurality of confluent parts formed on at least one of an inner side of the peripheral wall part and the peripheral wall part such that they are positioned in linear symmetry with respect to the short axis, wherein each of the confluent parts consist of three wall parts merging together with equal angles of 120° therebetween, wherein the plurality of confluent parts include at least one pair of confluent parts disposed symmetrically with respect to the short axis of the elongated cross-sectional shape of the peripheral wall part, and wherein the peripheral wall part comprises: an upper side peripheral wall part including at least one confluent part; a lower side peripheral wall part spaced from the upper side peripheral wall part, the lower side peripheral wall part including at least one confluent part; and a connecting wall part, connecting the upper side peripheral wall part to the lower side peripheral wall part, wherein the upper side peripheral wall part and the lower side peripheral wall part are disposed symmetrically with respect to the short axis, wherein the upper side peripheral wall part includes a first substantially H-shaped rib structure, the first H-shaped rib structure comprising two confluent parts, each of the two confluent parts being disposed symmetrically with respect to the long axis, and the lower side peripheral wall part includes a second substantially H-shaped rib structure, the second H-shaped rib structure comprising two confluent parts, each of the two confluent parts being disposed symmetrically with respect to the long axis, and wherein the connecting wall part comprises: a first vertical wall with a top end merging with the upper side peripheral wall part and a bottom end merging with the lower side peripheral wall part, and a second vertical wall with a top end merging with the upper side peripheral wall part and a bottom end merging with the lower side peripheral wall part, wherein the first vertical wall part and the second vertical wall part are disposed symmetrically with respect to the long axis.