| 摘要 |
An air flow sensing arrangement is disclosed for use in a vacuum cleaner. A plenum chamber or cavity established by a first wall and a second wall is provided adjacent to a fan inlet with all air from a bag chamber being directed radially inward therethrough toward an aperture in the first wall communicating with the fan inlet. The second wall is provided with openings adjacent to its outer periphery so that air is proportionally directed into the cavity along a plurality of paths. An air distribution chamber is established by the second wall and a secondary filter is supported on the second wall. Air is distributed by the distribution chamber about an entire outer surface of a wall portion of the second wall so as to maintan a consistent proportion of air flow through the openings into the cavity in the event irregular filter clogging occurs. A flow sensing device including a pivoting vane having a magnet thereon is disposed within the cavity so as to be within a path of air flowing through the openings. Air impinging against the vane causes it to pivot in an arcuate path to indicate a predetermined air flow level. A switch means is mounted in a position so as to be tangential to arcuate movement of the magnet during a portion of its movement with the switch means being actuated by the magnet when air flow in the cleaner drops to a predetermined low level thereby indicating a condition such as, for example, a full filter bag, low power setting on the cleaner and/or clogged hose.
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