| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a substitute structure of a noise-reducing annular structure for reducing sound components of noise produced by a fan without changing system efficiency in terms of a delivery air flow rate and a head (water head). <P>SOLUTION: A fan assembly 10 comprises: a shroud 12 having a through opening 14, around which the shroud defines an air conveying ring 17; a motor-fan assembly 20 which includes an axial fan 22 mounted to a central support of the through opening and rotatable about an axis of rotation; and a noise-reducing annular structure 34 fixed to the air conveying ring surrounding the axial fan and having a plurality of projections 36 which are arranged in succession in a circumferential direction and extend radially towards the axis of rotation of the fan and having circumferential both sides adjacent to the side edge, each projection having a face 38 which is directed towards the axis of rotation and is substantially parallel thereto, and a plurality of portions 43 radially recessed towards the air conveying ring 17. Each of the recessed portions is directed towards the axis of rotation of the fan and the profile of which in the axial direction is generally curvilinear and not parallel to the axis of rotation. <P>COPYRIGHT: (C)2013,JPO&INPIT |
