| 摘要 |
<p>Vacuum cleaner has a suction head contg. the fan and drive motor downstream in the direction of air flow from the main container or box; this box normally contains the paper dust collecting bag. Between this box and the fan is a second dust filter mounted on a support frame or basket; this frame or basket is composed of two or more concentric prismatic, e.g. cylindrical or truncated conical frames (25, 26, 27, 28) the outermost of which is connected to the casing or box frame (32). The opposite end of this frame, forming a ridge (29), is clothed in the filter cloth (31), which consequently follows the series of undulations over the pyramidal or similar projections of the frame. The secondary filter cloth is pref. a polyamide needle felt or polypropylene. A large area of secondary filter is obtd. within a comparatively small space.</p> |
