Patent ID: 8292578

Claim:
A material having an internal cooling passage formed therein, the cooling passage having a wall surface provided with cooling ribs thereon to allow a cooling medium to flow along the wall surface, wherein the cooling ribs include: a plurality of first cooling ribs disposed on the wall surface of the cooling passage, each of the first cooling ribs extending toward a first side edge of the wall surface from adjacent an intermediate line which extends between the first side edge of the wall surface and a second side edge of the wall surface and in a downstream direction of a flow of the cooling medium; a plurality of second cooling ribs disposed on the wall surface of the cooling passage, each of the second cooling ribs extending toward the second side edge of the wall surface from adjacent the intermediate line in the downstream direction of the flow of the cooling medium, wherein the plurality of the first ribs and the plurality of the second ribs are alternately arranged in the flow direction of the cooling medium, wherein the plurality of the first ribs and the plurality of the second ribs each have a cross section including a front rib surface, wherein the plurality of the first ribs and the plurality of the second ribs each have a back surface extending from the front surface and being one of streamlined in the flow direction of the cooling medium and shaped similarly to a streamline of the cooling medium in the flow direction, wherein the plurality of the first ribs and the plurality of the second ribs are arranged in a staggered array with respect to the flow direction of the cooling medium so that ones of the plurality of the first ribs are positioned between adjacent ones of the plurality of the second ribs, and the plurality of the first ribs and the plurality of the second ribs are each formed such that a length of each said rib in the flow direction progressively increases as each said rib extends from adjacent the passage center to the first and second side edges of the wall surface and the height of the back surface of each said rib reduces as each said rib extends in the flow direction of the cooling medium and becomes zero at a rearward edge of each said rib, and wherein an upper surface of each of the cooling ribs is streamlined or similarly shaped.