| 摘要 |
PROBLEM TO BE SOLVED: To restrain rotational noise NZ by reducing the energy of an interference sound and reduce the noise. SOLUTION: Plural fan bodies 30, 30,... formed by arranging plural blades 40, 40,... extending to the rotational axis direction by unequal pitch in the periphery direction are arranged in the rotational axis direction. The blades 40, 40,... are formed into a twist shape twisted around the rotational axis O in proportion to go from one side end surface of the blades (40, 40,...) to the other side end surface so that the blade shape of a cross section crossing orthogonally with the rotational axis O may be the same shape relative to the rotary axis center O at any sectional position. The blades 40, 40,... of adjacent fan bodies 30, 30 are continued, especially the blades 40, 40,... are formed into a twist shape of which twist angle is 50 deg. or more under the state extended from one side end of the main body entire length to the other side end. |
