GB1428018A - Filtering device for a smoking product - Google Patents

Abstract

1428018 Tobacco filters BRITISH-AMERICAN TOBACCO CO LTD 30 Oct 1973 [27 Feb 1973] 50406/73 Heading A2C A filtering device for a smoking product including a tobacco section which device comprises a filtering element and at least one channel formed in said element or surrounding structure, the channel, whose walls are impermeable to smoke, beinig completely enclosed when the device is in use, except at one end which is open for communicating, when the device is in use, with the tobacco of the tobacco section and at the other end which terminates in an opening communicating with the filtering material of the said elements at an intermediate point in its length, the said opening being so dimensioned that it and/or the filter material adjacent to it will gradually become substantially completely plugged with solid material when the tobacco of the tobacco section is smoked in use. The said channel may extend axially at the periphery of the filter element or may be formed axially within the filtering element. One or a plurality of channels may be provided. The channels may be of the same length or different lengths as illustraded in a typical embodiment (Fig. 3) in which 14 and 20 designate the orifices. In another embodiment the filtering element has a single tapering channel formed in the casing the largest cross section of the channel being at the open end adjacent the tobacco section. In Fig. 6 the filtration material 42 and an adjacent tobacco section 46 are held together by a memiber 47 which may be a portion of a cigarette holder. Formed within 47 is a channel 43 which connects the portion of the tobacco section closest to the filtering element 42 to the said element through an orifice near the mouthpiece end 44. The filtering material may be enrobed in a plastics sheath and the size of the opening may be 12-30 stubs guage.