| 摘要 |
PURPOSE:To improve efficiency of an axial-flow impeller and reduce its noise, by arranging the leading edge external contour part of a boss plate approximately to the center of rotation from its trailing edge external contour part as viewed in the direction of rotation of the axial-flow impeller so as to decrease a region of turbulent air flow spreading on a fan blade. CONSTITUTION:A turning locus surface generated at rotation of a boss plate 2 is decreased by arranging a leading edge external contour part P1 to the center side of rotation from a trailing edge external contour part P2 of the boss plate 2. While a turning locus surface generated at rotation of a sloped surface 1J of a fan blade 1 is moved to the internal diametric side by arranging a leading edge part 1E to the center side of rotation from a trailing edge part 1D of the sloped surface 1J of the fan blade 1. Accordingly, a region influenced by a turbulent air flow is decreased generating less resistance against air flowing through a surface of the fan blade 1, as a result the total pressure efficiency is improved. While a noise is also reduced by a similar reason. |
