Tobacco smoke filter

• US 3,888,160 A
• Filed: 08/31/1973
• Issued: 06/10/1975
• Est. Priority Date: 02/01/1971
• Status: Expired due to Term

• Current Assignee: David Thomas Westcott, Geoffrey Roger Woodman
• Original Assignee: David Thomas Westcott, Geoffrey Roger Woodman
• Inventors: Westcott, David Thomas, Woodman, Geoffrey Roger
• Primary Examiner(s): Lake, Roy
• Assistant Examiner(s): Coan, James F.
• Application Number:
  US05/393,591
• Time in Patent Office: 648 Days
• Field of Search: 93/1C,77FT 131/261R,261A,261B,10.5,11,12,13,14
• US Class Current: 493/42
• CPC Class Codes: A24D 3/0283 with means for a non-axial smoke flow

Abstract

A tobacco smoke filter is in the form of a cylinder having a low resistance core and a high resistance end wall which cause smoke flow radially through the cylinder wall. The filter is preferably made by compacting the central core of a filter plug to form the dense end wall. Such filter plugs have an efficiency of 2 or 3 times that of a conventional filter of the same pressure drop.

Claims

1. A method of making a selectively compacted tobacco smoke filter comprising providing a cylinder of filter material and compacting only a core section of the cylinder, leaving an annular uncompacted wall extending around the compacted core section.

2. A method as claimed in claim 1, comprising providing a double length cylinder of filter material, compacting a core section only of the cylinder from both ends simultaneously to provide a central plug section denser than that of the cylindrical wall and separating the cylinder transversely at the central plug section to provide two hollow cylindrical filters each with an annular uncompacted wall extending around the compacted core section.

3. A method of making a selectively compacted tobacco smoke filter comprising providing a cylinder of filter material having a separate core of filter material therein and compacting said separate core of filter mateRial, leaving an annularly uncompacted wall extending around the compacted core section.

4. A method as claimed in claim 3, wherein the cylinder and core are of differing densities.

5. A method of making a selectively compacted tobacco smoke filter comprising providing a cylinder of filter material in the form of a homogeneous rod, compacting only a core section of the cylinder, leaving an annular uncompacted wall extending around the compacted core section and simultaneously cutting or shearing a core from said rod as the core is completed.

6. A method of making a selectively compacted tobacco smoke filter comprising providing a double length cylinder of filter material having a separate core of filter material therein, compacting said separate core section only of the cylinder from both ends simultaneously to provide a central plug section denser than that of the cylindrical wall and separating the cylinder transversely at the central plug section to provide two hollow cylindrical filters each with an annular uncompacted wall extending around the compacted core section.

7. A method as claimed in claim 6, wherein the cylinder and core are of differing densities.

8. A method of making a selectively compacted tobacco smoke filter comprising providing a double length cylinder of filter material in the form of a homogeneous rod, compacting a core section only of the homogeneous rod from both ends simultaneously to provide a central plug section denser than that of the cylindrical wall, separating the cylinder transversely at the central plug section to provide two hollow cylindrical filters each with an annular uncompacted wall extending around the compacted core section and simultaneously cutting or shearing a core from said rod as the core is compacted.