| 摘要 |
<p>A low-noise propeller fan of a low manufacturing cost by improving the rigidity of fan blades (7) in the axial and radial directions thereof and reducing the thickness of the fan blades to as great an extent as possible in spite of the large diameter of the fan, whereby the moldability of and molding time for the material for the propeller fan is improved and reduced respectively, and by minimizing the amount of use of a material the cost of which accounts for a large percentage of the fan manufacturing cost. A plurality of plate type circumferential ribs (4) projecting from acting faces toward the negative pressure side and a plurality of radial ribs (5) projecting from the acting faces toward the negative pressure side are provided on the reverse (negative pressure) side (9) of the fan blades (7), whereby the thickness of the fan blades is reduced, so that the amount of material used decreases. This causes the influence of the ribs upon a flow of the air to be minimized, and the occurrence of noise to be suppressed.</p> |
