| 摘要 |
<p>PURPOSE:To reduce sharply powder loss due to a circular flow and improve the fan efficiency in such a way that drift blades are provided at the diffuser part located between the impeller and the return path for leading the flow from the impeller to the return path after changing its path gradually in the axial direction. CONSTITUTION:Since a diffuser path 13 is formed inclined in the axial direction by drift blades 12, the flow direction varies gradually toward the axial direction being guided by the drift blades 12, flowing through a return path 10, and discharged out of a fan discharge port 14. In consequence, the circular flow on the stream on the outer peripheral outlet port of the impeller 1 as existent in a conventional example is absolutely eliminated by means of the drift blades 12 and guide vanes 2, power loss due to the circular flow can be sharply reduced, so that sharp improvement of the fan pressure and efficiency can be effected. Besides, because the axial positions of the drift blades 12 are gradually shifted from vanes, generated compressional waves are offset to one another by producing a shift of timing and occurence of siren-like sound can be prevented.</p> |
