| 摘要 |
A filter bag construction for filtering dirt, dust and other materials from the exhaust air flow of an upright vacuum cleaner, wherein an elongated, non-disposable outer fabric bag having a longitudinally extending delivery tube therein provides one stage of filtration and a disposable, inner paper filter bag provides a second stage of filtration. The filter bag construction may be used without the inner, paper filter bag when maximum filtration efficiency is not required or with the inner, paper filter bag when high filtration efficiency and/or the convenience of a disposable filter element is desired. When operating as a single stage filter, the upper end of a flow channeling conduit in the lower end of the outer bag is positioned in the lower end of the delivery tube and, when operating as a two-stage filter, the upper end of the conduit is shifted to another position in the outer bag so that unfiltered air from the cleaner is initially channeled into the inner filter bag. The delivery tube of the outer filter bag is of flexible material and terminates above the lower end of the outer bag to facilitate shifting of the flow channeling conduit between its respective positions. |
