| 摘要 |
433,664. Vacuum cleaners. ELECTROLUX, Ltd., Luton.-(Assignees of Inventia Patent - Verwertungs-Ges. ; 10, Herrenacker, Schaffhausen, Switzerland) July 6, 1934, No. 19939. Convention date, July 8, 1933. [Class 8 (i)] [See also Group XXVI] A vacuum cleaner is provided with a series of fan impellers mounted upon a common shaft driven by a single motor and means for directing the air stream set up to flow through the impellers either in series or in parallel. In Figs. 2 and 3, the fan impellers 21, 22, are working in parallel by reason of the position of a valve member 32 with openings 37 which communicate with passages 30 in a partition member 25 between the two impellers. In addition peripheral openings 35 on a flange part of the valve member 32 coincide with openings 31 in member 25 to allow suction air to the inlet of the impeller 22. In Figs. 4 and 5 the valve member 32 is shown in position for series operation of the impellers, the passages 30 and 31 in member 25 being closed and the air directed from the outlet of fan impeller 21 through openings 38 in valve 32 which coincide with openings 29 in member 25, to the inlet of impeller 22. The valve member 32 is normally operated by a knob 39 which extends through the casing but may be actuated by automatic means, such as a bellows, subjected to the variations in the suction.
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