| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise and vibration without decreasing cooling ability by arranging a plurality of blades unevenly in a vehicle plate having position angles shown by a specific equation. SOLUTION: Z number of blades 24 are provided at unequal intervals in the radial direction in a vehicle plate 23. The uppermost blade 24 is referred to as the first, with the next blade 24 in the clockwise direction referred to as the second, and the next blade 24 referred to as the third. The position angleθn of the nth blade 24 is the angle between the straight line connecting the center of gravity with the rotation center of the first blade 24. The position angleθn of the nth blade 24 is set so as to fulfill the equationθn =θn0 +θmax×sin[2π×m×(n-1)/Z} (However, m is an optional integer from 1 to Z-1 because it expresses the order of rotations). In this way, the noise level is reduced on the whole by arranging the blades 24 at unequal intervals.
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