A smoking article, a filter and a method of manufacturing a smoking article

Abstract

A smoking article includes a filter arrangement comprising a first filter section and a second filter section, the second filter section being located downstream of the first filter section, and a ventilation arrangement configured to provide a user controllable level of ventilation into the first filter section. A resistance to gaseous flow through the length of the second filter section is lower than a resistance to gaseous flow through the length of the first filter section, and the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied.

1 . A smoking article comprising:
 a filter arrangement comprising a first filter section and a second filter section, the second filter section being located downstream of the first filter section; and   a ventilation arrangement configured to provide a user controllable level of ventilation into the first filter section, wherein the smoking article comprises a first part and a second part and the level of ventilation can be selected by selecting a position of the second part relative to the first part;   wherein a resistance to gaseous flow through the length of the second filter section is lower than a resistance to gaseous flow through the length of the first filter section; and   the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied.   
     
     
         2 . The smoking article as claimed in  claim 1 , wherein the first filter section has a first tow weight of fibrous filtration material, and the second filter section has a second tow weight of fibrous filtration material; and
 the second tow weight of fibrous filtration material is lower than the first tow weight of fibrous material.   
     
     
         3 . The smoking article as claimed in  claim 1 , wherein the pressure drop per unit length of the first filter section is more than 5 mmH2O/mm, and the pressure drop per unit length of the second filter section is less than 5 mmH2O/mm. 
     
     
         4 . The smoking article as claimed in  claim 1 , wherein the resistance to gaseous flow through the second filter section is lower than the resistance to gaseous flow through the first filter section by at least a multiple value selected from one of: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15. 
     
     
         5 . The smoking article as claimed in  claim 1 , wherein the first filter section is formed from a first homogenous filtration material, and the second filter section is formed from a second homogenous filtration material. 
     
     
         6 . The smoking article as claimed in  claim 1 , wherein the second filter section is separate from the first filter section, and/or moveable relative to the first filter section to control the ventilation into the first filter section. 
     
     
         7 . The smoking article as claimed in  claim 1 , wherein the second part further comprises a sleeve configured to move relative to the first filter section, wherein the second filter section is fixed within the sleeve, and the level of ventilation is varied by altering a position of the sleeve relative to the first filter section. 
     
     
         8 . The smoking article as claimed in  claim 7 , wherein the sleeve is rotatable with respect to the first filter section, and the level of ventilation is varied by altering an angular position of the sleeve relative to the first filter section. 
     
     
         9 . The smoking article as claimed in  claim 1 , wherein the first filter section has a length of 5 to 25 mm, the second filter section has a length of 5 to 25 mm, and/or the ventilation arrangement provides ventilating air at 6 to 35 mm from a mouth end of the smoking article. 
     
     
         10 . The smoking article as claimed in  claim 1 , wherein the first and second filter sections comprise tow filaments, and the first filter section differs from the second filter section by one or more of: tow weight, number of tow filaments in unit volume, cross-section of tow filaments and degree of crimping. 
     
     
         11 . The smoking article as claimed in  claim 1 , wherein the second filter section comprises at least one air passage extending longitudinally through the length thereof. 
     
     
         12 . The smoking article as claimed in  claim 11 , wherein the air passage has a diameter of between 1 and 7 mm. 
     
     
         13 . The smoking article as claimed in  claim 1 , wherein the second filter section comprises fibrous filtration material formed having an annular cross section. 
     
     
         14 . The smoking article as claimed in  claim 1 , wherein the second filter section comprises a tube of fibrous filtration material and the air passage extends along a central longitudinal axis through the length of the second filter section. 
     
     
         15 . A filter for a smoking article comprising:
 a filter arrangement comprising a first filter section and a second filter section, the second filter section being located downstream of the first filter section; and   a ventilation arrangement configured to provide a user controllable level of ventilation into the first filter section, wherein the filter comprises a first part and a second part and the level of ventilation can be selected by selecting a position of the second part relative to the first part;   wherein a resistance to gaseous flow through the length of the second filter section is lower than a resistance to gaseous flow through the length of the first filter section; and   the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied.   
     
     
         16 . A method of manufacturing a smoking article, the method comprising:
 forming a first filter section with a first resistance to gaseous flow through its length;   forming a separate second filter section with a second resistance to gaseous flow through its length, wherein the second resistance to gaseous flow is lower than the first resistance to gaseous flow; and   assembling the first filter section and second filter section with one or more additional components to form the smoking article such that the second filter section is located downstream of the first filter section in the smoking article, wherein the smoking article is configured to allow the ingress of a selectively variable amount of air.