| 摘要 |
PROBLEM TO BE SOLVED: To blow large amount of cooling air to an engine body without enlarging a cooling fan. SOLUTION: This cooling fan 12 producing cooling air for cooling the engine body 8 has a disk 31 mounted on a crank shaft 1; and a plurality of fan blades 32 installed on the surface of the disk 31 so as to project in the shaft direction. Each fan blade 32 is radially installed at the intervals of the specified air blowing space 33 in the circumferential direction, the surface 31a of the disk 31 between the fan blades is gradually inclined in the diameter direction so that the height in the shaft direction of the air blowing space 33 is increased toward the outside in the diameter direction, and inclined in the circumferential direction so that the height in the shaft direction of the air blowing space 33 is increased toward the front side in the rotation direction of the fan blades 32 adjacent in the rotation direction from the rear surface side in the rotation direction of the fan blade 32.
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