A Filter Unit for a Smoking Article

Abstract

A filter unit for a smoking article includes a tube having a first portion and a second portion, wherein an inner diameter of the first portion is different from an inner diameter of the second portion. The filter unit also includes a sleeve at least partially surrounding the tube. Also described are a smoking article having the filter unit and a kit including a smoking article and the filter unit.

1 . A filter unit for a smoking article comprising:
 a tube having a first portion and a second portion, wherein an inner diameter of the first portion is different from an inner diameter of the second portion; and   a sleeve at least partially surrounding the tube.   
     
     
         2 . A filter unit according to  claim 1 , wherein the second portion is at a distal end of the filter unit. 
     
     
         3 . A filter unit according to  claim 2 , wherein the inner diameter of the second portion decreases with distance from the distal end of the filter unit. 
     
     
         4 . A filter unit according to  claim 1 ,  2  or  3 , wherein an inner diameter of the second portion is greater than an inner diameter of the first portion. 
     
     
         5 . A filter unit according to any one of  claims 1  to  4 , wherein an outer diameter of the second portion is greater than an outer diameter of the first portion. 
     
     
         6 . A filter unit according to any one of  claims 1  to  4 , wherein an outer diameter of the first portion is substantially the same as an outer diameter of the second portion. 
     
     
         7 . A filter unit according to any one of  claims 1  to  6 ,
 wherein each of the first portion and the second portion has a first end and a second end, and 
 the second end of the first portion adjoins the first end of the second portion and has an inner diameter substantially the same as the first end of the second portion. 
 
     
     
         8 . A filter unit according to any one of  claims 1  to  7 , wherein the tube is formed from paper, card, cardboard or plastic. 
     
     
         9 . A filter unit according to any one of  claims 1  to  8 , comprising:
 a cylindrical element, 
 wherein the sleeve at least partially surrounds the cylindrical element. 
 
     
     
         10 . A filter unit according to any one of  claims 1  to  9 , wherein the cylindrical element is formed from filter material and comprises a body having an end surface adjacent to the tube and a recess formed in the end surface. 
     
     
         11 . A filter unit according to any one of  claims 1  to  10 , wherein the element comprises a smoke modifying substance disposed within the filter material of the element. 
     
     
         12 . A filter unit according to claim ii, wherein the smoke modifying substance comprises an encapsulated substance. 
     
     
         13 . A filter unit according to any one of  claims 1  to  12 , wherein the filter unit is arranged to be coupled to a smoking article by a user. 
     
     
         14 . A smoking article comprising a filter unit according to any one of  claims 1  to  13 . 
     
     
         15 . A smoking article according to  claim 14 , wherein the second portion of the tube is disposed at a mouth end of the smoking article. 
     
     
         16 . A kit comprising a smoking article and a filter unit according to any one of  claims 1  to  13 .