| 摘要 |
PURPOSE: To minimize the generation of a harsh grating noise resulted from the holes or projections of a basket in its rotation. CONSTITUTION: The holes 18 (or projections) of a basket 14 are formed in an inclination arrangement that the holes 18 (or projections) on other axial lines are arranged at substantially equal circumferential intervals within the range of circumferential pitch interval of the holes 18 (or projections) of the axial tip (top stage) line and shifted from the holes 18 (or projections) of the axial tip line. According to this structure, the phases of sound waves generated therefrom are shifted, these sound waves with shifted phases are totaled and the sound fluctuation component concerning noise is consequently made zero by the mutual interference thereof. |
