| 摘要 |
<p>The fan has a common impeller with two sets of a blades (11, 16) which move air through separate ducts (13, 21), particularly for extracting air through a central inner duct (13) and supplying air through an annular duct (21) concentric around the inner duct, for simultaneous extract and fresh air supply. The inner blade assembly (11) forms an axial fan whilst the outer blades (16) are arranged to give centrifugal action. The hub (13b) of the outer blades may be connected to the inner blades and may have a radial disc portion (15) to form an outwardly open annular space containing the outer blades (16) of the centrifugal outer fan.</p> |
